1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2016 */
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>
31 #ifdef EXPERIMENTAL_DANE
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
58 * X509_check_host provides sane certificate hostname checking, but was added
59 * to OpenSSL late, after other projects forked off the code-base. So in
60 * addition to guarding against the base version number, beware that LibreSSL
61 * does not (at this time) support this function.
63 * If LibreSSL gains a different API, perhaps via libtls, then we'll probably
64 * opt to disentangle and ask a LibreSSL user to provide glue for a third
65 * crypto provider for libtls instead of continuing to tie the OpenSSL glue
66 * into even twistier knots. If LibreSSL gains the same API, we can just
67 * change this guard and punt the issue for a while longer.
69 #ifndef LIBRESSL_VERSION_NUMBER
70 # if OPENSSL_VERSION_NUMBER >= 0x010100000L
71 # define EXIM_HAVE_OPENSSL_CHECKHOST
73 # if OPENSSL_VERSION_NUMBER >= 0x010000000L \
74 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
75 # define EXIM_HAVE_OPENSSL_CHECKHOST
79 #if !defined(LIBRESSL_VERSION_NUMBER) \
80 || LIBRESSL_VERSION_NUMBER >= 0x20010000L
81 # if !defined(OPENSSL_NO_ECDH)
82 # if OPENSSL_VERSION_NUMBER >= 0x0090800fL
83 # define EXIM_HAVE_ECDH
85 # if OPENSSL_VERSION_NUMBER >= 0x10002000L
86 # if OPENSSL_VERSION_NUMBER < 0x10100000L
87 # define EXIM_HAVE_OPENSSL_ECDH_AUTO
89 # define EXIM_HAVE_OPENSSL_EC_NIST2NID
94 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
95 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
99 /* Structure for collecting random data for seeding. */
101 typedef struct randstuff
{
106 /* Local static variables */
108 static BOOL client_verify_callback_called
= FALSE
;
109 static BOOL server_verify_callback_called
= FALSE
;
110 static const uschar
*sid_ctx
= US
"exim";
112 /* We have three different contexts to care about.
114 Simple case: client, `client_ctx`
115 As a client, we can be doing a callout or cut-through delivery while receiving
116 a message. So we have a client context, which should have options initialised
117 from the SMTP Transport.
120 There are two cases: with and without ServerNameIndication from the client.
121 Given TLS SNI, we can be using different keys, certs and various other
122 configuration settings, because they're re-expanded with $tls_sni set. This
123 allows vhosting with TLS. This SNI is sent in the handshake.
124 A client might not send SNI, so we need a fallback, and an initial setup too.
125 So as a server, we start out using `server_ctx`.
126 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
127 `server_sni` from `server_ctx` and then initialise settings by re-expanding
131 static SSL_CTX
*client_ctx
= NULL
;
132 static SSL_CTX
*server_ctx
= NULL
;
133 static SSL
*client_ssl
= NULL
;
134 static SSL
*server_ssl
= NULL
;
136 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
137 static SSL_CTX
*server_sni
= NULL
;
140 static char ssl_errstring
[256];
142 static int ssl_session_timeout
= 200;
143 static BOOL client_verify_optional
= FALSE
;
144 static BOOL server_verify_optional
= FALSE
;
146 static BOOL reexpand_tls_files_for_sni
= FALSE
;
149 typedef struct tls_ext_ctx_cb
{
154 STACK_OF(X509
) *verify_stack
; /* chain for verifying the proof */
158 uschar
*file_expanded
;
159 OCSP_RESPONSE
*response
;
162 X509_STORE
*verify_store
; /* non-null if status requested */
163 BOOL verify_required
;
168 /* these are cached from first expand */
169 uschar
*server_cipher_list
;
170 /* only passed down to tls_error: */
172 const uschar
* verify_cert_hostnames
;
173 #ifndef DISABLE_EVENT
174 uschar
* event_action
;
178 /* should figure out a cleanup of API to handle state preserved per
179 implementation, for various reasons, which can be void * in the APIs.
180 For now, we hack around it. */
181 tls_ext_ctx_cb
*client_static_cbinfo
= NULL
;
182 tls_ext_ctx_cb
*server_static_cbinfo
= NULL
;
185 setup_certs(SSL_CTX
*sctx
, uschar
*certs
, uschar
*crl
, host_item
*host
, BOOL optional
,
186 int (*cert_vfy_cb
)(int, X509_STORE_CTX
*) );
189 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
190 static int tls_servername_cb(SSL
*s
, int *ad ARG_UNUSED
, void *arg
);
193 static int tls_server_stapling_cb(SSL
*s
, void *arg
);
197 /*************************************************
199 *************************************************/
201 /* Called from lots of places when errors occur before actually starting to do
202 the TLS handshake, that is, while the session is still in clear. Always returns
203 DEFER for a server and FAIL for a client so that most calls can use "return
204 tls_error(...)" to do this processing and then give an appropriate return. A
205 single function is used for both server and client, because it is called from
206 some shared functions.
209 prefix text to include in the logged error
210 host NULL if setting up a server;
211 the connected host if setting up a client
212 msg error message or NULL if we should ask OpenSSL
214 Returns: OK/DEFER/FAIL
218 tls_error(uschar
* prefix
, const host_item
* host
, uschar
* msg
)
222 ERR_error_string(ERR_get_error(), ssl_errstring
);
223 msg
= (uschar
*)ssl_errstring
;
228 log_write(0, LOG_MAIN
, "H=%s [%s] TLS error on connection (%s): %s",
229 host
->name
, host
->address
, prefix
, msg
);
234 uschar
*conn_info
= smtp_get_connection_info();
235 if (Ustrncmp(conn_info
, US
"SMTP ", 5) == 0)
237 /* I'd like to get separated H= here, but too hard for now */
238 log_write(0, LOG_MAIN
, "TLS error on %s (%s): %s",
239 conn_info
, prefix
, msg
);
246 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
247 /*************************************************
248 * Callback to generate RSA key *
249 *************************************************/
257 Returns: pointer to generated key
261 rsa_callback(SSL
*s
, int export
, int keylength
)
264 #ifdef EXIM_HAVE_RSA_GENKEY_EX
265 BIGNUM
*bn
= BN_new();
268 export
= export
; /* Shut picky compilers up */
269 DEBUG(D_tls
) debug_printf("Generating %d bit RSA key...\n", keylength
);
271 #ifdef EXIM_HAVE_RSA_GENKEY_EX
272 if ( !BN_set_word(bn
, (unsigned long)RSA_F4
)
273 || !(rsa_key
= RSA_new())
274 || !RSA_generate_key_ex(rsa_key
, keylength
, bn
, NULL
)
277 if (!(rsa_key
= RSA_generate_key(keylength
, RSA_F4
, NULL
, NULL
)))
281 ERR_error_string(ERR_get_error(), ssl_errstring
);
282 log_write(0, LOG_MAIN
|LOG_PANIC
, "TLS error (RSA_generate_key): %s",
295 x509_store_dump_cert_s_names(X509_STORE * store)
297 STACK_OF(X509_OBJECT) * roots= store->objs;
299 static uschar name[256];
301 for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
303 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
304 if(tmp_obj->type == X509_LU_X509)
306 X509 * current_cert= tmp_obj->data.x509;
307 X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name));
308 name[sizeof(name)-1] = '\0';
309 debug_printf(" %s\n", name);
317 #ifndef DISABLE_EVENT
319 verify_event(tls_support
* tlsp
, X509
* cert
, int depth
, const uschar
* dn
,
320 BOOL
*calledp
, const BOOL
*optionalp
, const uschar
* what
)
326 ev
= tlsp
== &tls_out
? client_static_cbinfo
->event_action
: event_action
;
329 DEBUG(D_tls
) debug_printf("verify_event: %s %d\n", what
, depth
);
330 old_cert
= tlsp
->peercert
;
331 tlsp
->peercert
= X509_dup(cert
);
332 /* NB we do not bother setting peerdn */
333 if ((yield
= event_raise(ev
, US
"tls:cert", string_sprintf("%d", depth
))))
335 log_write(0, LOG_MAIN
, "[%s] %s verify denied by event-action: "
336 "depth=%d cert=%s: %s",
337 tlsp
== &tls_out
? deliver_host_address
: sender_host_address
,
338 what
, depth
, dn
, yield
);
342 if (old_cert
) tlsp
->peercert
= old_cert
; /* restore 1st failing cert */
343 return 1; /* reject (leaving peercert set) */
345 DEBUG(D_tls
) debug_printf("Event-action verify failure overridden "
346 "(host in tls_try_verify_hosts)\n");
348 X509_free(tlsp
->peercert
);
349 tlsp
->peercert
= old_cert
;
355 /*************************************************
356 * Callback for verification *
357 *************************************************/
359 /* The SSL library does certificate verification if set up to do so. This
360 callback has the current yes/no state is in "state". If verification succeeded,
361 we set the certificate-verified flag. If verification failed, what happens
362 depends on whether the client is required to present a verifiable certificate
365 If verification is optional, we change the state to yes, but still log the
366 verification error. For some reason (it really would help to have proper
367 documentation of OpenSSL), this callback function then gets called again, this
368 time with state = 1. We must take care not to set the private verified flag on
369 the second time through.
371 Note: this function is not called if the client fails to present a certificate
372 when asked. We get here only if a certificate has been received. Handling of
373 optional verification for this case is done when requesting SSL to verify, by
374 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
376 May be called multiple times for different issues with a certificate, even
377 for a given "depth" in the certificate chain.
380 preverify_ok current yes/no state as 1/0
381 x509ctx certificate information.
382 tlsp per-direction (client vs. server) support data
383 calledp has-been-called flag
384 optionalp verification-is-optional flag
386 Returns: 0 if verification should fail, otherwise 1
390 verify_callback(int preverify_ok
, X509_STORE_CTX
*x509ctx
,
391 tls_support
*tlsp
, BOOL
*calledp
, BOOL
*optionalp
)
393 X509
* cert
= X509_STORE_CTX_get_current_cert(x509ctx
);
394 int depth
= X509_STORE_CTX_get_error_depth(x509ctx
);
397 X509_NAME_oneline(X509_get_subject_name(cert
), CS dn
, sizeof(dn
));
398 dn
[sizeof(dn
)-1] = '\0';
400 if (preverify_ok
== 0)
402 log_write(0, LOG_MAIN
, "[%s] SSL verify error: depth=%d error=%s cert=%s",
403 tlsp
== &tls_out
? deliver_host_address
: sender_host_address
,
405 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx
)),
411 tlsp
->peercert
= X509_dup(cert
); /* record failing cert */
412 return 0; /* reject */
414 DEBUG(D_tls
) debug_printf("SSL verify failure overridden (host in "
415 "tls_try_verify_hosts)\n");
420 DEBUG(D_tls
) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth
, dn
);
422 if (tlsp
== &tls_out
&& client_static_cbinfo
->u_ocsp
.client
.verify_store
)
423 { /* client, wanting stapling */
424 /* Add the server cert's signing chain as the one
425 for the verification of the OCSP stapled information. */
427 if (!X509_STORE_add_cert(client_static_cbinfo
->u_ocsp
.client
.verify_store
,
430 sk_X509_push(client_static_cbinfo
->verify_stack
, cert
);
433 #ifndef DISABLE_EVENT
434 if (verify_event(tlsp
, cert
, depth
, dn
, calledp
, optionalp
, US
"SSL"))
435 return 0; /* reject, with peercert set */
440 const uschar
* verify_cert_hostnames
;
442 if ( tlsp
== &tls_out
443 && ((verify_cert_hostnames
= client_static_cbinfo
->verify_cert_hostnames
)))
444 /* client, wanting hostname check */
447 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
448 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
449 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
451 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
452 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
455 const uschar
* list
= verify_cert_hostnames
;
458 while ((name
= string_nextinlist(&list
, &sep
, NULL
, 0)))
459 if ((rc
= X509_check_host(cert
, CCS name
, 0,
460 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
461 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
,
466 log_write(0, LOG_MAIN
, "[%s] SSL verify error: internal error",
467 tlsp
== &tls_out
? deliver_host_address
: sender_host_address
);
474 if (!tls_is_name_for_cert(verify_cert_hostnames
, cert
))
477 log_write(0, LOG_MAIN
,
478 "[%s] SSL verify error: certificate name mismatch: \"%s\"",
479 tlsp
== &tls_out
? deliver_host_address
: sender_host_address
,
485 tlsp
->peercert
= X509_dup(cert
); /* record failing cert */
486 return 0; /* reject */
488 DEBUG(D_tls
) debug_printf("SSL verify failure overridden (host in "
489 "tls_try_verify_hosts)\n");
493 #ifndef DISABLE_EVENT
494 if (verify_event(tlsp
, cert
, depth
, dn
, calledp
, optionalp
, US
"SSL"))
495 return 0; /* reject, with peercert set */
498 DEBUG(D_tls
) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
499 *calledp
? "" : " authenticated", dn
);
500 if (!*calledp
) tlsp
->certificate_verified
= TRUE
;
504 return 1; /* accept, at least for this level */
508 verify_callback_client(int preverify_ok
, X509_STORE_CTX
*x509ctx
)
510 return verify_callback(preverify_ok
, x509ctx
, &tls_out
,
511 &client_verify_callback_called
, &client_verify_optional
);
515 verify_callback_server(int preverify_ok
, X509_STORE_CTX
*x509ctx
)
517 return verify_callback(preverify_ok
, x509ctx
, &tls_in
,
518 &server_verify_callback_called
, &server_verify_optional
);
522 #ifdef EXPERIMENTAL_DANE
524 /* This gets called *by* the dane library verify callback, which interposes
528 verify_callback_client_dane(int preverify_ok
, X509_STORE_CTX
* x509ctx
)
530 X509
* cert
= X509_STORE_CTX_get_current_cert(x509ctx
);
532 #ifndef DISABLE_EVENT
533 int depth
= X509_STORE_CTX_get_error_depth(x509ctx
);
534 BOOL dummy_called
, optional
= FALSE
;
537 X509_NAME_oneline(X509_get_subject_name(cert
), CS dn
, sizeof(dn
));
538 dn
[sizeof(dn
)-1] = '\0';
540 DEBUG(D_tls
) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
541 preverify_ok
? "ok":"BAD", depth
, dn
);
543 #ifndef DISABLE_EVENT
544 if (verify_event(&tls_out
, cert
, depth
, dn
,
545 &dummy_called
, &optional
, US
"DANE"))
546 return 0; /* reject, with peercert set */
549 if (preverify_ok
== 1)
550 tls_out
.dane_verified
=
551 tls_out
.certificate_verified
= TRUE
;
554 int err
= X509_STORE_CTX_get_error(x509ctx
);
556 debug_printf(" - err %d '%s'\n", err
, X509_verify_cert_error_string(err
));
557 if (err
== X509_V_ERR_APPLICATION_VERIFICATION
)
563 #endif /*EXPERIMENTAL_DANE*/
566 /*************************************************
567 * Information callback *
568 *************************************************/
570 /* The SSL library functions call this from time to time to indicate what they
571 are doing. We copy the string to the debugging output when TLS debugging has
583 info_callback(SSL
*s
, int where
, int ret
)
587 DEBUG(D_tls
) debug_printf("SSL info: %s\n", SSL_state_string_long(s
));
592 /*************************************************
593 * Initialize for DH *
594 *************************************************/
596 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
599 sctx The current SSL CTX (inbound or outbound)
600 dhparam DH parameter file or fixed parameter identity string
601 host connected host, if client; NULL if server
603 Returns: TRUE if OK (nothing to set up, or setup worked)
607 init_dh(SSL_CTX
*sctx
, uschar
*dhparam
, const host_item
*host
)
614 if (!expand_check(dhparam
, US
"tls_dhparam", &dhexpanded
))
617 if (!dhexpanded
|| !*dhexpanded
)
618 bio
= BIO_new_mem_buf(CS
std_dh_prime_default(), -1);
619 else if (dhexpanded
[0] == '/')
621 if (!(bio
= BIO_new_file(CS dhexpanded
, "r")))
623 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded
),
624 host
, US
strerror(errno
));
630 if (Ustrcmp(dhexpanded
, "none") == 0)
632 DEBUG(D_tls
) debug_printf("Requested no DH parameters.\n");
636 if (!(pem
= std_dh_prime_named(dhexpanded
)))
638 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded
),
639 host
, US
strerror(errno
));
642 bio
= BIO_new_mem_buf(CS pem
, -1);
645 if (!(dh
= PEM_read_bio_DHparams(bio
, NULL
, NULL
, NULL
)))
648 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded
),
653 /* Even if it is larger, we silently return success rather than cause things
654 * to fail out, so that a too-large DH will not knock out all TLS; it's a
655 * debatable choice. */
656 if ((8*DH_size(dh
)) > tls_dh_max_bits
)
659 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
660 8*DH_size(dh
), tls_dh_max_bits
);
664 SSL_CTX_set_tmp_dh(sctx
, dh
);
666 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
667 dhexpanded
? dhexpanded
: US
"default", 8*DH_size(dh
));
679 /*************************************************
680 * Initialize for ECDH *
681 *************************************************/
683 /* Load parameters for ECDH encryption.
685 For now, we stick to NIST P-256 because: it's simple and easy to configure;
686 it avoids any patent issues that might bite redistributors; despite events in
687 the news and concerns over curve choices, we're not cryptographers, we're not
688 pretending to be, and this is "good enough" to be better than no support,
689 protecting against most adversaries. Given another year or two, there might
690 be sufficient clarity about a "right" way forward to let us make an informed
691 decision, instead of a knee-jerk reaction.
693 Longer-term, we should look at supporting both various named curves and
694 external files generated with "openssl ecparam", much as we do for init_dh().
695 We should also support "none" as a value, to explicitly avoid initialisation.
700 sctx The current SSL CTX (inbound or outbound)
701 host connected host, if client; NULL if server
703 Returns: TRUE if OK (nothing to set up, or setup worked)
707 init_ecdh(SSL_CTX
* sctx
, host_item
* host
)
709 #ifdef OPENSSL_NO_ECDH
718 if (host
) /* No ECDH setup for clients, only for servers */
721 # ifndef EXIM_HAVE_ECDH
723 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
727 if (!expand_check(tls_eccurve
, US
"tls_eccurve", &exp_curve
))
729 if (!exp_curve
|| !*exp_curve
)
732 # ifdef EXIM_HAVE_OPENSSL_ECDH_AUTO
733 /* check if new enough library to support auto ECDH temp key parameter selection */
734 if (Ustrcmp(exp_curve
, "auto") == 0)
736 DEBUG(D_tls
) debug_printf(
737 "ECDH temp key parameter settings: OpenSSL 1.2+ autoselection\n");
738 SSL_CTX_set_ecdh_auto(sctx
, 1);
743 DEBUG(D_tls
) debug_printf("ECDH: curve '%s'\n", exp_curve
);
744 if ( (nid
= OBJ_sn2nid (CCS exp_curve
)) == NID_undef
745 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
746 && (nid
= EC_curve_nist2nid(CCS exp_curve
)) == NID_undef
750 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'",
756 if (!(ecdh
= EC_KEY_new_by_curve_name(nid
)))
758 tls_error(US
"Unable to create ec curve", host
, NULL
);
762 /* The "tmp" in the name here refers to setting a temporary key
763 not to the stability of the interface. */
765 if ((rv
= SSL_CTX_set_tmp_ecdh(sctx
, ecdh
) == 0))
766 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve
), host
, NULL
);
768 DEBUG(D_tls
) debug_printf("ECDH: enabled '%s' curve\n", exp_curve
);
773 # endif /*EXIM_HAVE_ECDH*/
774 #endif /*OPENSSL_NO_ECDH*/
781 /*************************************************
782 * Load OCSP information into state *
783 *************************************************/
784 /* Called to load the server OCSP response from the given file into memory, once
785 caller has determined this is needed. Checks validity. Debugs a message
788 ASSUMES: single response, for single cert.
791 sctx the SSL_CTX* to update
792 cbinfo various parts of session state
793 expanded the filename putatively holding an OCSP response
798 ocsp_load_response(SSL_CTX
*sctx
, tls_ext_ctx_cb
*cbinfo
, const uschar
*expanded
)
801 OCSP_RESPONSE
* resp
;
802 OCSP_BASICRESP
* basic_response
;
803 OCSP_SINGLERESP
* single_response
;
804 ASN1_GENERALIZEDTIME
* rev
, * thisupd
, * nextupd
;
806 unsigned long verify_flags
;
807 int status
, reason
, i
;
809 cbinfo
->u_ocsp
.server
.file_expanded
= string_copy(expanded
);
810 if (cbinfo
->u_ocsp
.server
.response
)
812 OCSP_RESPONSE_free(cbinfo
->u_ocsp
.server
.response
);
813 cbinfo
->u_ocsp
.server
.response
= NULL
;
816 if (!(bio
= BIO_new_file(CS cbinfo
->u_ocsp
.server
.file_expanded
, "rb")))
818 DEBUG(D_tls
) debug_printf("Failed to open OCSP response file \"%s\"\n",
819 cbinfo
->u_ocsp
.server
.file_expanded
);
823 resp
= d2i_OCSP_RESPONSE_bio(bio
, NULL
);
827 DEBUG(D_tls
) debug_printf("Error reading OCSP response.\n");
831 if ((status
= OCSP_response_status(resp
)) != OCSP_RESPONSE_STATUS_SUCCESSFUL
)
833 DEBUG(D_tls
) debug_printf("OCSP response not valid: %s (%d)\n",
834 OCSP_response_status_str(status
), status
);
838 if (!(basic_response
= OCSP_response_get1_basic(resp
)))
841 debug_printf("OCSP response parse error: unable to extract basic response.\n");
845 sk
= cbinfo
->verify_stack
;
846 verify_flags
= OCSP_NOVERIFY
; /* check sigs, but not purpose */
848 /* May need to expose ability to adjust those flags?
849 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
850 OCSP_TRUSTOTHER OCSP_NOINTERN */
852 /* This does a full verify on the OCSP proof before we load it for serviing
853 up; possibly overkill - just date-checks might be nice enough.
855 OCSP_basic_verify takes a "store" arg, but does not
856 use it for the chain verification, which is all we do
857 when OCSP_NOVERIFY is set. The content from the wire
858 "basic_response" and a cert-stack "sk" are all that is used.
860 We have a stack, loaded in setup_certs() if tls_verify_certificates
861 was a file (not a directory, or "system"). It is unfortunate we
862 cannot used the connection context store, as that would neatly
863 handle the "system" case too, but there seems to be no library
864 function for getting a stack from a store.
865 We do not free the stack since it could be needed a second time for
868 Seperately we might try to replace using OCSP_basic_verify() - which seems to not
869 be a public interface into the OpenSSL library (there's no manual entry) -
870 But what with? We also use OCSP_basic_verify in the client stapling callback.
871 And there we NEED it; we miust verify that status... unless the
872 library does it for us anyway? */
874 if ((i
= OCSP_basic_verify(basic_response
, sk
, NULL
, verify_flags
)) < 0)
878 ERR_error_string(ERR_get_error(), ssl_errstring
);
879 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring
);
884 /* Here's the simplifying assumption: there's only one response, for the
885 one certificate we use, and nothing for anything else in a chain. If this
886 proves false, we need to extract a cert id from our issued cert
887 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
888 right cert in the stack and then calls OCSP_single_get0_status()).
890 I'm hoping to avoid reworking a bunch more of how we handle state here. */
892 if (!(single_response
= OCSP_resp_get0(basic_response
, 0)))
895 debug_printf("Unable to get first response from OCSP basic response.\n");
899 status
= OCSP_single_get0_status(single_response
, &reason
, &rev
, &thisupd
, &nextupd
);
900 if (status
!= V_OCSP_CERTSTATUS_GOOD
)
902 DEBUG(D_tls
) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
903 OCSP_cert_status_str(status
), status
,
904 OCSP_crl_reason_str(reason
), reason
);
908 if (!OCSP_check_validity(thisupd
, nextupd
, EXIM_OCSP_SKEW_SECONDS
, EXIM_OCSP_MAX_AGE
))
910 DEBUG(D_tls
) debug_printf("OCSP status invalid times.\n");
915 cbinfo
->u_ocsp
.server
.response
= resp
;
919 if (running_in_test_harness
)
921 extern char ** environ
;
923 if (environ
) for (p
= USS environ
; *p
!= NULL
; p
++)
924 if (Ustrncmp(*p
, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
926 DEBUG(D_tls
) debug_printf("Supplying known bad OCSP response\n");
927 goto supply_response
;
932 #endif /*!DISABLE_OCSP*/
937 /* Create and install a selfsigned certificate, for use in server mode */
940 tls_install_selfsign(SSL_CTX
* sctx
)
948 where
= US
"allocating pkey";
949 if (!(pkey
= EVP_PKEY_new()))
952 where
= US
"allocating cert";
953 if (!(x509
= X509_new()))
956 where
= US
"generating pkey";
957 /* deprecated, use RSA_generate_key_ex() */
958 if (!(rsa
= RSA_generate_key(1024, RSA_F4
, NULL
, NULL
)))
961 where
= US
"assiging pkey";
962 if (!EVP_PKEY_assign_RSA(pkey
, rsa
))
965 X509_set_version(x509
, 2); /* N+1 - version 3 */
966 ASN1_INTEGER_set(X509_get_serialNumber(x509
), 0);
967 X509_gmtime_adj(X509_get_notBefore(x509
), 0);
968 X509_gmtime_adj(X509_get_notAfter(x509
), (long)60 * 60); /* 1 hour */
969 X509_set_pubkey(x509
, pkey
);
971 name
= X509_get_subject_name(x509
);
972 X509_NAME_add_entry_by_txt(name
, "C",
973 MBSTRING_ASC
, CUS
"UK", -1, -1, 0);
974 X509_NAME_add_entry_by_txt(name
, "O",
975 MBSTRING_ASC
, CUS
"Exim Developers", -1, -1, 0);
976 X509_NAME_add_entry_by_txt(name
, "CN",
977 MBSTRING_ASC
, CUS smtp_active_hostname
, -1, -1, 0);
978 X509_set_issuer_name(x509
, name
);
980 where
= US
"signing cert";
981 if (!X509_sign(x509
, pkey
, EVP_md5()))
984 where
= US
"installing selfsign cert";
985 if (!SSL_CTX_use_certificate(sctx
, x509
))
988 where
= US
"installing selfsign key";
989 if (!SSL_CTX_use_PrivateKey(sctx
, pkey
))
995 (void) tls_error(where
, NULL
, NULL
);
996 if (x509
) X509_free(x509
);
997 if (pkey
) EVP_PKEY_free(pkey
);
1004 /*************************************************
1005 * Expand key and cert file specs *
1006 *************************************************/
1008 /* Called once during tls_init and possibly again during TLS setup, for a
1009 new context, if Server Name Indication was used and tls_sni was seen in
1010 the certificate string.
1013 sctx the SSL_CTX* to update
1014 cbinfo various parts of session state
1016 Returns: OK/DEFER/FAIL
1020 tls_expand_session_files(SSL_CTX
*sctx
, tls_ext_ctx_cb
*cbinfo
)
1024 if (!cbinfo
->certificate
)
1026 if (cbinfo
->host
) /* client */
1029 if (tls_install_selfsign(sctx
) != OK
)
1034 if (Ustrstr(cbinfo
->certificate
, US
"tls_sni") ||
1035 Ustrstr(cbinfo
->certificate
, US
"tls_in_sni") ||
1036 Ustrstr(cbinfo
->certificate
, US
"tls_out_sni")
1038 reexpand_tls_files_for_sni
= TRUE
;
1040 if (!expand_check(cbinfo
->certificate
, US
"tls_certificate", &expanded
))
1043 if (expanded
!= NULL
)
1045 DEBUG(D_tls
) debug_printf("tls_certificate file %s\n", expanded
);
1046 if (!SSL_CTX_use_certificate_chain_file(sctx
, CS expanded
))
1047 return tls_error(string_sprintf(
1048 "SSL_CTX_use_certificate_chain_file file=%s", expanded
),
1049 cbinfo
->host
, NULL
);
1052 if (cbinfo
->privatekey
!= NULL
&&
1053 !expand_check(cbinfo
->privatekey
, US
"tls_privatekey", &expanded
))
1056 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1057 of the expansion is an empty string, ignore it also, and assume the private
1058 key is in the same file as the certificate. */
1060 if (expanded
&& *expanded
)
1062 DEBUG(D_tls
) debug_printf("tls_privatekey file %s\n", expanded
);
1063 if (!SSL_CTX_use_PrivateKey_file(sctx
, CS expanded
, SSL_FILETYPE_PEM
))
1064 return tls_error(string_sprintf(
1065 "SSL_CTX_use_PrivateKey_file file=%s", expanded
), cbinfo
->host
, NULL
);
1069 #ifndef DISABLE_OCSP
1070 if (cbinfo
->is_server
&& cbinfo
->u_ocsp
.server
.file
)
1072 if (!expand_check(cbinfo
->u_ocsp
.server
.file
, US
"tls_ocsp_file", &expanded
))
1075 if (expanded
&& *expanded
)
1077 DEBUG(D_tls
) debug_printf("tls_ocsp_file %s\n", expanded
);
1078 if ( cbinfo
->u_ocsp
.server
.file_expanded
1079 && (Ustrcmp(expanded
, cbinfo
->u_ocsp
.server
.file_expanded
) == 0))
1081 DEBUG(D_tls
) debug_printf(" - value unchanged, using existing values\n");
1084 ocsp_load_response(sctx
, cbinfo
, expanded
);
1095 /*************************************************
1096 * Callback to handle SNI *
1097 *************************************************/
1099 /* Called when acting as server during the TLS session setup if a Server Name
1100 Indication extension was sent by the client.
1102 API documentation is OpenSSL s_server.c implementation.
1105 s SSL* of the current session
1106 ad unknown (part of OpenSSL API) (unused)
1107 arg Callback of "our" registered data
1109 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
1112 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1114 tls_servername_cb(SSL
*s
, int *ad ARG_UNUSED
, void *arg
)
1116 const char *servername
= SSL_get_servername(s
, TLSEXT_NAMETYPE_host_name
);
1117 tls_ext_ctx_cb
*cbinfo
= (tls_ext_ctx_cb
*) arg
;
1119 int old_pool
= store_pool
;
1122 return SSL_TLSEXT_ERR_OK
;
1124 DEBUG(D_tls
) debug_printf("Received TLS SNI \"%s\"%s\n", servername
,
1125 reexpand_tls_files_for_sni
? "" : " (unused for certificate selection)");
1127 /* Make the extension value available for expansion */
1128 store_pool
= POOL_PERM
;
1129 tls_in
.sni
= string_copy(US servername
);
1130 store_pool
= old_pool
;
1132 if (!reexpand_tls_files_for_sni
)
1133 return SSL_TLSEXT_ERR_OK
;
1135 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
1136 not confident that memcpy wouldn't break some internal reference counting.
1137 Especially since there's a references struct member, which would be off. */
1139 if (!(server_sni
= SSL_CTX_new(SSLv23_server_method())))
1141 ERR_error_string(ERR_get_error(), ssl_errstring
);
1142 DEBUG(D_tls
) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring
);
1143 return SSL_TLSEXT_ERR_NOACK
;
1146 /* Not sure how many of these are actually needed, since SSL object
1147 already exists. Might even need this selfsame callback, for reneg? */
1149 SSL_CTX_set_info_callback(server_sni
, SSL_CTX_get_info_callback(server_ctx
));
1150 SSL_CTX_set_mode(server_sni
, SSL_CTX_get_mode(server_ctx
));
1151 SSL_CTX_set_options(server_sni
, SSL_CTX_get_options(server_ctx
));
1152 SSL_CTX_set_timeout(server_sni
, SSL_CTX_get_timeout(server_ctx
));
1153 SSL_CTX_set_tlsext_servername_callback(server_sni
, tls_servername_cb
);
1154 SSL_CTX_set_tlsext_servername_arg(server_sni
, cbinfo
);
1156 if ( !init_dh(server_sni
, cbinfo
->dhparam
, NULL
)
1157 || !init_ecdh(server_sni
, NULL
)
1159 return SSL_TLSEXT_ERR_NOACK
;
1161 if (cbinfo
->server_cipher_list
)
1162 SSL_CTX_set_cipher_list(server_sni
, CS cbinfo
->server_cipher_list
);
1163 #ifndef DISABLE_OCSP
1164 if (cbinfo
->u_ocsp
.server
.file
)
1166 SSL_CTX_set_tlsext_status_cb(server_sni
, tls_server_stapling_cb
);
1167 SSL_CTX_set_tlsext_status_arg(server_sni
, cbinfo
);
1171 if ((rc
= setup_certs(server_sni
, tls_verify_certificates
, tls_crl
, NULL
, FALSE
,
1172 verify_callback_server
)) != OK
)
1173 return SSL_TLSEXT_ERR_NOACK
;
1175 /* do this after setup_certs, because this can require the certs for verifying
1176 OCSP information. */
1177 if ((rc
= tls_expand_session_files(server_sni
, cbinfo
)) != OK
)
1178 return SSL_TLSEXT_ERR_NOACK
;
1180 DEBUG(D_tls
) debug_printf("Switching SSL context.\n");
1181 SSL_set_SSL_CTX(s
, server_sni
);
1183 return SSL_TLSEXT_ERR_OK
;
1185 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
1190 #ifndef DISABLE_OCSP
1192 /*************************************************
1193 * Callback to handle OCSP Stapling *
1194 *************************************************/
1196 /* Called when acting as server during the TLS session setup if the client
1197 requests OCSP information with a Certificate Status Request.
1199 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
1205 tls_server_stapling_cb(SSL
*s
, void *arg
)
1207 const tls_ext_ctx_cb
*cbinfo
= (tls_ext_ctx_cb
*) arg
;
1208 uschar
*response_der
;
1209 int response_der_len
;
1212 debug_printf("Received TLS status request (OCSP stapling); %s response\n",
1213 cbinfo
->u_ocsp
.server
.response
? "have" : "lack");
1215 tls_in
.ocsp
= OCSP_NOT_RESP
;
1216 if (!cbinfo
->u_ocsp
.server
.response
)
1217 return SSL_TLSEXT_ERR_NOACK
;
1219 response_der
= NULL
;
1220 response_der_len
= i2d_OCSP_RESPONSE(cbinfo
->u_ocsp
.server
.response
,
1222 if (response_der_len
<= 0)
1223 return SSL_TLSEXT_ERR_NOACK
;
1225 SSL_set_tlsext_status_ocsp_resp(server_ssl
, response_der
, response_der_len
);
1226 tls_in
.ocsp
= OCSP_VFIED
;
1227 return SSL_TLSEXT_ERR_OK
;
1232 time_print(BIO
* bp
, const char * str
, ASN1_GENERALIZEDTIME
* time
)
1234 BIO_printf(bp
, "\t%s: ", str
);
1235 ASN1_GENERALIZEDTIME_print(bp
, time
);
1240 tls_client_stapling_cb(SSL
*s
, void *arg
)
1242 tls_ext_ctx_cb
* cbinfo
= arg
;
1243 const unsigned char * p
;
1245 OCSP_RESPONSE
* rsp
;
1246 OCSP_BASICRESP
* bs
;
1249 DEBUG(D_tls
) debug_printf("Received TLS status response (OCSP stapling):");
1250 len
= SSL_get_tlsext_status_ocsp_resp(s
, &p
);
1253 /* Expect this when we requested ocsp but got none */
1254 if (cbinfo
->u_ocsp
.client
.verify_required
&& LOGGING(tls_cipher
))
1255 log_write(0, LOG_MAIN
, "Received TLS status callback, null content");
1257 DEBUG(D_tls
) debug_printf(" null\n");
1258 return cbinfo
->u_ocsp
.client
.verify_required
? 0 : 1;
1261 if(!(rsp
= d2i_OCSP_RESPONSE(NULL
, &p
, len
)))
1263 tls_out
.ocsp
= OCSP_FAILED
;
1264 if (LOGGING(tls_cipher
))
1265 log_write(0, LOG_MAIN
, "Received TLS cert status response, parse error");
1267 DEBUG(D_tls
) debug_printf(" parse error\n");
1271 if(!(bs
= OCSP_response_get1_basic(rsp
)))
1273 tls_out
.ocsp
= OCSP_FAILED
;
1274 if (LOGGING(tls_cipher
))
1275 log_write(0, LOG_MAIN
, "Received TLS cert status response, error parsing response");
1277 DEBUG(D_tls
) debug_printf(" error parsing response\n");
1278 OCSP_RESPONSE_free(rsp
);
1282 /* We'd check the nonce here if we'd put one in the request. */
1283 /* However that would defeat cacheability on the server so we don't. */
1285 /* This section of code reworked from OpenSSL apps source;
1286 The OpenSSL Project retains copyright:
1287 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1292 ASN1_GENERALIZEDTIME
*rev
, *thisupd
, *nextupd
;
1294 DEBUG(D_tls
) bp
= BIO_new_fp(stderr
, BIO_NOCLOSE
);
1296 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1298 /* Use the chain that verified the server cert to verify the stapled info */
1299 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1301 if ((i
= OCSP_basic_verify(bs
, cbinfo
->verify_stack
,
1302 cbinfo
->u_ocsp
.client
.verify_store
, 0)) <= 0)
1304 tls_out
.ocsp
= OCSP_FAILED
;
1305 if (LOGGING(tls_cipher
))
1306 log_write(0, LOG_MAIN
, "Received TLS cert status response, itself unverifiable");
1307 BIO_printf(bp
, "OCSP response verify failure\n");
1308 ERR_print_errors(bp
);
1312 BIO_printf(bp
, "OCSP response well-formed and signed OK\n");
1314 /*XXX So we have a good stapled OCSP status. How do we know
1315 it is for the cert of interest? OpenSSL 1.1.0 has a routine
1316 OCSP_resp_find_status() which matches on a cert id, which presumably
1317 we should use. Making an id needs OCSP_cert_id_new(), which takes
1318 issuerName, issuerKey, serialNumber. Are they all in the cert?
1320 For now, carry on blindly accepting the resp. */
1323 OCSP_SINGLERESP
* single
;
1325 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
1326 if (OCSP_resp_count(bs
) != 1)
1328 STACK_OF(OCSP_SINGLERESP
) * sresp
= bs
->tbsResponseData
->responses
;
1329 if (sk_OCSP_SINGLERESP_num(sresp
) != 1)
1332 tls_out
.ocsp
= OCSP_FAILED
;
1333 log_write(0, LOG_MAIN
, "OCSP stapling "
1334 "with multiple responses not handled");
1337 single
= OCSP_resp_get0(bs
, 0);
1338 status
= OCSP_single_get0_status(single
, &reason
, &rev
,
1339 &thisupd
, &nextupd
);
1342 DEBUG(D_tls
) time_print(bp
, "This OCSP Update", thisupd
);
1343 DEBUG(D_tls
) if(nextupd
) time_print(bp
, "Next OCSP Update", nextupd
);
1344 if (!OCSP_check_validity(thisupd
, nextupd
,
1345 EXIM_OCSP_SKEW_SECONDS
, EXIM_OCSP_MAX_AGE
))
1347 tls_out
.ocsp
= OCSP_FAILED
;
1348 DEBUG(D_tls
) ERR_print_errors(bp
);
1349 log_write(0, LOG_MAIN
, "Server OSCP dates invalid");
1353 DEBUG(D_tls
) BIO_printf(bp
, "Certificate status: %s\n",
1354 OCSP_cert_status_str(status
));
1357 case V_OCSP_CERTSTATUS_GOOD
:
1358 tls_out
.ocsp
= OCSP_VFIED
;
1361 case V_OCSP_CERTSTATUS_REVOKED
:
1362 tls_out
.ocsp
= OCSP_FAILED
;
1363 log_write(0, LOG_MAIN
, "Server certificate revoked%s%s",
1364 reason
!= -1 ? "; reason: " : "",
1365 reason
!= -1 ? OCSP_crl_reason_str(reason
) : "");
1366 DEBUG(D_tls
) time_print(bp
, "Revocation Time", rev
);
1369 tls_out
.ocsp
= OCSP_FAILED
;
1370 log_write(0, LOG_MAIN
,
1371 "Server certificate status unknown, in OCSP stapling");
1376 i
= cbinfo
->u_ocsp
.client
.verify_required
? 0 : 1;
1381 OCSP_RESPONSE_free(rsp
);
1384 #endif /*!DISABLE_OCSP*/
1387 /*************************************************
1388 * Initialize for TLS *
1389 *************************************************/
1391 /* Called from both server and client code, to do preliminary initialization
1392 of the library. We allocate and return a context structure.
1395 ctxp returned SSL context
1396 host connected host, if client; NULL if server
1397 dhparam DH parameter file
1398 certificate certificate file
1399 privatekey private key
1400 ocsp_file file of stapling info (server); flag for require ocsp (client)
1401 addr address if client; NULL if server (for some randomness)
1402 cbp place to put allocated callback context
1404 Returns: OK/DEFER/FAIL
1408 tls_init(SSL_CTX
**ctxp
, host_item
*host
, uschar
*dhparam
, uschar
*certificate
,
1410 #ifndef DISABLE_OCSP
1413 address_item
*addr
, tls_ext_ctx_cb
** cbp
)
1418 tls_ext_ctx_cb
* cbinfo
;
1420 cbinfo
= store_malloc(sizeof(tls_ext_ctx_cb
));
1421 cbinfo
->certificate
= certificate
;
1422 cbinfo
->privatekey
= privatekey
;
1423 #ifndef DISABLE_OCSP
1424 cbinfo
->verify_stack
= NULL
;
1425 if ((cbinfo
->is_server
= host
==NULL
))
1427 cbinfo
->u_ocsp
.server
.file
= ocsp_file
;
1428 cbinfo
->u_ocsp
.server
.file_expanded
= NULL
;
1429 cbinfo
->u_ocsp
.server
.response
= NULL
;
1432 cbinfo
->u_ocsp
.client
.verify_store
= NULL
;
1434 cbinfo
->dhparam
= dhparam
;
1435 cbinfo
->server_cipher_list
= NULL
;
1436 cbinfo
->host
= host
;
1437 #ifndef DISABLE_EVENT
1438 cbinfo
->event_action
= NULL
;
1441 SSL_load_error_strings(); /* basic set up */
1442 OpenSSL_add_ssl_algorithms();
1444 #ifdef EXIM_HAVE_SHA256
1445 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1446 list of available digests. */
1447 EVP_add_digest(EVP_sha256());
1450 /* Create a context.
1451 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1452 negotiation in the different methods; as far as I can tell, the only
1453 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1454 when OpenSSL is built without SSLv2 support.
1455 By disabling with openssl_options, we can let admins re-enable with the
1458 *ctxp
= SSL_CTX_new(host
? SSLv23_client_method() : SSLv23_server_method());
1460 if (!*ctxp
) return tls_error(US
"SSL_CTX_new", host
, NULL
);
1462 /* It turns out that we need to seed the random number generator this early in
1463 order to get the full complement of ciphers to work. It took me roughly a day
1464 of work to discover this by experiment.
1466 On systems that have /dev/urandom, SSL may automatically seed itself from
1467 there. Otherwise, we have to make something up as best we can. Double check
1473 gettimeofday(&r
.tv
, NULL
);
1476 RAND_seed((uschar
*)(&r
), sizeof(r
));
1477 RAND_seed((uschar
*)big_buffer
, big_buffer_size
);
1478 if (addr
!= NULL
) RAND_seed((uschar
*)addr
, sizeof(addr
));
1481 return tls_error(US
"RAND_status", host
,
1482 US
"unable to seed random number generator");
1485 /* Set up the information callback, which outputs if debugging is at a suitable
1488 DEBUG(D_tls
) SSL_CTX_set_info_callback(*ctxp
, (void (*)())info_callback
);
1490 /* Automatically re-try reads/writes after renegotiation. */
1491 (void) SSL_CTX_set_mode(*ctxp
, SSL_MODE_AUTO_RETRY
);
1493 /* Apply administrator-supplied work-arounds.
1494 Historically we applied just one requested option,
1495 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1496 moved to an administrator-controlled list of options to specify and
1497 grandfathered in the first one as the default value for "openssl_options".
1499 No OpenSSL version number checks: the options we accept depend upon the
1500 availability of the option value macros from OpenSSL. */
1502 okay
= tls_openssl_options_parse(openssl_options
, &init_options
);
1504 return tls_error(US
"openssl_options parsing failed", host
, NULL
);
1508 DEBUG(D_tls
) debug_printf("setting SSL CTX options: %#lx\n", init_options
);
1509 if (!(SSL_CTX_set_options(*ctxp
, init_options
)))
1510 return tls_error(string_sprintf(
1511 "SSL_CTX_set_option(%#lx)", init_options
), host
, NULL
);
1514 DEBUG(D_tls
) debug_printf("no SSL CTX options to set\n");
1516 /* Initialize with DH parameters if supplied */
1517 /* Initialize ECDH temp key parameter selection */
1519 if ( !init_dh(*ctxp
, dhparam
, host
)
1520 || !init_ecdh(*ctxp
, host
)
1524 /* Set up certificate and key (and perhaps OCSP info) */
1526 if ((rc
= tls_expand_session_files(*ctxp
, cbinfo
)) != OK
)
1529 /* If we need to handle SNI or OCSP, do so */
1531 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1532 # ifndef DISABLE_OCSP
1533 if (!(cbinfo
->verify_stack
= sk_X509_new_null()))
1535 DEBUG(D_tls
) debug_printf("failed to create stack for stapling verify\n");
1540 if (host
== NULL
) /* server */
1542 # ifndef DISABLE_OCSP
1543 /* We check u_ocsp.server.file, not server.response, because we care about if
1544 the option exists, not what the current expansion might be, as SNI might
1545 change the certificate and OCSP file in use between now and the time the
1546 callback is invoked. */
1547 if (cbinfo
->u_ocsp
.server
.file
)
1549 SSL_CTX_set_tlsext_status_cb(server_ctx
, tls_server_stapling_cb
);
1550 SSL_CTX_set_tlsext_status_arg(server_ctx
, cbinfo
);
1553 /* We always do this, so that $tls_sni is available even if not used in
1555 SSL_CTX_set_tlsext_servername_callback(*ctxp
, tls_servername_cb
);
1556 SSL_CTX_set_tlsext_servername_arg(*ctxp
, cbinfo
);
1558 # ifndef DISABLE_OCSP
1560 if(ocsp_file
) /* wanting stapling */
1562 if (!(cbinfo
->u_ocsp
.client
.verify_store
= X509_STORE_new()))
1564 DEBUG(D_tls
) debug_printf("failed to create store for stapling verify\n");
1567 SSL_CTX_set_tlsext_status_cb(*ctxp
, tls_client_stapling_cb
);
1568 SSL_CTX_set_tlsext_status_arg(*ctxp
, cbinfo
);
1573 cbinfo
->verify_cert_hostnames
= NULL
;
1575 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
1576 /* Set up the RSA callback */
1577 SSL_CTX_set_tmp_rsa_callback(*ctxp
, rsa_callback
);
1580 /* Finally, set the timeout, and we are done */
1582 SSL_CTX_set_timeout(*ctxp
, ssl_session_timeout
);
1583 DEBUG(D_tls
) debug_printf("Initialized TLS\n");
1593 /*************************************************
1594 * Get name of cipher in use *
1595 *************************************************/
1598 Argument: pointer to an SSL structure for the connection
1599 buffer to use for answer
1601 pointer to number of bits for cipher
1606 construct_cipher_name(SSL
*ssl
, uschar
*cipherbuf
, int bsize
, int *bits
)
1608 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1609 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1610 the accessor functions use const in the prototype. */
1611 const SSL_CIPHER
*c
;
1614 ver
= (const uschar
*)SSL_get_version(ssl
);
1616 c
= (const SSL_CIPHER
*) SSL_get_current_cipher(ssl
);
1617 SSL_CIPHER_get_bits(c
, bits
);
1619 string_format(cipherbuf
, bsize
, "%s:%s:%u", ver
,
1620 SSL_CIPHER_get_name(c
), *bits
);
1622 DEBUG(D_tls
) debug_printf("Cipher: %s\n", cipherbuf
);
1627 peer_cert(SSL
* ssl
, tls_support
* tlsp
, uschar
* peerdn
, unsigned bsize
)
1629 /*XXX we might consider a list-of-certs variable for the cert chain.
1630 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
1631 in list-handling functions, also consider the difference between the entire
1632 chain and the elements sent by the peer. */
1634 /* Will have already noted peercert on a verify fail; possibly not the leaf */
1635 if (!tlsp
->peercert
)
1636 tlsp
->peercert
= SSL_get_peer_certificate(ssl
);
1637 /* Beware anonymous ciphers which lead to server_cert being NULL */
1640 X509_NAME_oneline(X509_get_subject_name(tlsp
->peercert
), CS peerdn
, bsize
);
1641 peerdn
[bsize
-1] = '\0';
1642 tlsp
->peerdn
= peerdn
; /*XXX a static buffer... */
1645 tlsp
->peerdn
= NULL
;
1652 /*************************************************
1653 * Set up for verifying certificates *
1654 *************************************************/
1656 /* Load certs from file, return TRUE on success */
1659 chain_from_pem_file(const uschar
* file
, STACK_OF(X509
) * verify_stack
)
1664 if (!(bp
= BIO_new_file(CS file
, "r"))) return FALSE
;
1665 while ((x
= PEM_read_bio_X509(bp
, NULL
, 0, NULL
)))
1666 sk_X509_push(verify_stack
, x
);
1673 /* Called by both client and server startup
1676 sctx SSL_CTX* to initialise
1677 certs certs file or NULL
1678 crl CRL file or NULL
1679 host NULL in a server; the remote host in a client
1680 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1681 otherwise passed as FALSE
1682 cert_vfy_cb Callback function for certificate verification
1684 Returns: OK/DEFER/FAIL
1688 setup_certs(SSL_CTX
*sctx
, uschar
*certs
, uschar
*crl
, host_item
*host
, BOOL optional
,
1689 int (*cert_vfy_cb
)(int, X509_STORE_CTX
*) )
1691 uschar
*expcerts
, *expcrl
;
1693 if (!expand_check(certs
, US
"tls_verify_certificates", &expcerts
))
1696 if (expcerts
&& *expcerts
)
1698 /* Tell the library to use its compiled-in location for the system default
1699 CA bundle. Then add the ones specified in the config, if any. */
1701 if (!SSL_CTX_set_default_verify_paths(sctx
))
1702 return tls_error(US
"SSL_CTX_set_default_verify_paths", host
, NULL
);
1704 if (Ustrcmp(expcerts
, "system") != 0)
1706 struct stat statbuf
;
1708 if (Ustat(expcerts
, &statbuf
) < 0)
1710 log_write(0, LOG_MAIN
|LOG_PANIC
,
1711 "failed to stat %s for certificates", expcerts
);
1717 if ((statbuf
.st_mode
& S_IFMT
) == S_IFDIR
)
1718 { file
= NULL
; dir
= expcerts
; }
1721 file
= expcerts
; dir
= NULL
;
1722 #ifndef DISABLE_OCSP
1723 /* In the server if we will be offering an OCSP proof, load chain from
1724 file for verifying the OCSP proof at load time. */
1727 && statbuf
.st_size
> 0
1728 && server_static_cbinfo
->u_ocsp
.server
.file
1729 && !chain_from_pem_file(file
, server_static_cbinfo
->verify_stack
)
1732 log_write(0, LOG_MAIN
|LOG_PANIC
,
1733 "failed to load cert hain from %s", file
);
1739 /* If a certificate file is empty, the next function fails with an
1740 unhelpful error message. If we skip it, we get the correct behaviour (no
1741 certificates are recognized, but the error message is still misleading (it
1742 says no certificate was supplied). But this is better. */
1744 if ( (!file
|| statbuf
.st_size
> 0)
1745 && !SSL_CTX_load_verify_locations(sctx
, CS file
, CS dir
))
1746 return tls_error(US
"SSL_CTX_load_verify_locations", host
, NULL
);
1748 /* Load the list of CAs for which we will accept certs, for sending
1749 to the client. This is only for the one-file tls_verify_certificates
1751 If a list isn't loaded into the server, but
1752 some verify locations are set, the server end appears to make
1753 a wildcard reqest for client certs.
1754 Meanwhile, the client library as default behaviour *ignores* the list
1755 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1756 Because of this, and that the dir variant is likely only used for
1757 the public-CA bundle (not for a private CA), not worth fixing.
1761 STACK_OF(X509_NAME
) * names
= SSL_load_client_CA_file(CS file
);
1763 DEBUG(D_tls
) debug_printf("Added %d certificate authorities.\n",
1764 sk_X509_NAME_num(names
));
1765 SSL_CTX_set_client_CA_list(sctx
, names
);
1770 /* Handle a certificate revocation list. */
1772 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1774 /* This bit of code is now the version supplied by Lars Mainka. (I have
1775 merely reformatted it into the Exim code style.)
1777 "From here I changed the code to add support for multiple crl's
1778 in pem format in one file or to support hashed directory entries in
1779 pem format instead of a file. This method now uses the library function
1780 X509_STORE_load_locations to add the CRL location to the SSL context.
1781 OpenSSL will then handle the verify against CA certs and CRLs by
1782 itself in the verify callback." */
1784 if (!expand_check(crl
, US
"tls_crl", &expcrl
)) return DEFER
;
1785 if (expcrl
&& *expcrl
)
1787 struct stat statbufcrl
;
1788 if (Ustat(expcrl
, &statbufcrl
) < 0)
1790 log_write(0, LOG_MAIN
|LOG_PANIC
,
1791 "failed to stat %s for certificates revocation lists", expcrl
);
1796 /* is it a file or directory? */
1798 X509_STORE
*cvstore
= SSL_CTX_get_cert_store(sctx
);
1799 if ((statbufcrl
.st_mode
& S_IFMT
) == S_IFDIR
)
1803 DEBUG(D_tls
) debug_printf("SSL CRL value is a directory %s\n", dir
);
1809 DEBUG(D_tls
) debug_printf("SSL CRL value is a file %s\n", file
);
1811 if (X509_STORE_load_locations(cvstore
, CS file
, CS dir
) == 0)
1812 return tls_error(US
"X509_STORE_load_locations", host
, NULL
);
1814 /* setting the flags to check against the complete crl chain */
1816 X509_STORE_set_flags(cvstore
,
1817 X509_V_FLAG_CRL_CHECK
|X509_V_FLAG_CRL_CHECK_ALL
);
1821 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1823 /* If verification is optional, don't fail if no certificate */
1825 SSL_CTX_set_verify(sctx
,
1826 SSL_VERIFY_PEER
| (optional
? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT
),
1835 /*************************************************
1836 * Start a TLS session in a server *
1837 *************************************************/
1839 /* This is called when Exim is running as a server, after having received
1840 the STARTTLS command. It must respond to that command, and then negotiate
1844 require_ciphers allowed ciphers
1846 Returns: OK on success
1847 DEFER for errors before the start of the negotiation
1848 FAIL for errors during the negotation; the server can't
1853 tls_server_start(const uschar
*require_ciphers
)
1857 tls_ext_ctx_cb
*cbinfo
;
1858 static uschar peerdn
[256];
1859 static uschar cipherbuf
[256];
1861 /* Check for previous activation */
1863 if (tls_in
.active
>= 0)
1865 tls_error(US
"STARTTLS received after TLS started", NULL
, US
"");
1866 smtp_printf("554 Already in TLS\r\n");
1870 /* Initialize the SSL library. If it fails, it will already have logged
1873 rc
= tls_init(&server_ctx
, NULL
, tls_dhparam
, tls_certificate
, tls_privatekey
,
1874 #ifndef DISABLE_OCSP
1877 NULL
, &server_static_cbinfo
);
1878 if (rc
!= OK
) return rc
;
1879 cbinfo
= server_static_cbinfo
;
1881 if (!expand_check(require_ciphers
, US
"tls_require_ciphers", &expciphers
))
1884 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1885 were historically separated by underscores. So that I can use either form in my
1886 tests, and also for general convenience, we turn underscores into hyphens here.
1891 uschar
* s
= expciphers
;
1892 while (*s
!= 0) { if (*s
== '_') *s
= '-'; s
++; }
1893 DEBUG(D_tls
) debug_printf("required ciphers: %s\n", expciphers
);
1894 if (!SSL_CTX_set_cipher_list(server_ctx
, CS expciphers
))
1895 return tls_error(US
"SSL_CTX_set_cipher_list", NULL
, NULL
);
1896 cbinfo
->server_cipher_list
= expciphers
;
1899 /* If this is a host for which certificate verification is mandatory or
1900 optional, set up appropriately. */
1902 tls_in
.certificate_verified
= FALSE
;
1903 #ifdef EXPERIMENTAL_DANE
1904 tls_in
.dane_verified
= FALSE
;
1906 server_verify_callback_called
= FALSE
;
1908 if (verify_check_host(&tls_verify_hosts
) == OK
)
1910 rc
= setup_certs(server_ctx
, tls_verify_certificates
, tls_crl
, NULL
,
1911 FALSE
, verify_callback_server
);
1912 if (rc
!= OK
) return rc
;
1913 server_verify_optional
= FALSE
;
1915 else if (verify_check_host(&tls_try_verify_hosts
) == OK
)
1917 rc
= setup_certs(server_ctx
, tls_verify_certificates
, tls_crl
, NULL
,
1918 TRUE
, verify_callback_server
);
1919 if (rc
!= OK
) return rc
;
1920 server_verify_optional
= TRUE
;
1923 /* Prepare for new connection */
1925 if (!(server_ssl
= SSL_new(server_ctx
))) return tls_error(US
"SSL_new", NULL
, NULL
);
1927 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1929 * With the SSL_clear(), we get strange interoperability bugs with
1930 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1931 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1933 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1934 * session shutdown. In this case, we have a brand new object and there's no
1935 * obvious reason to immediately clear it. I'm guessing that this was
1936 * originally added because of incomplete initialisation which the clear fixed,
1937 * in some historic release.
1940 /* Set context and tell client to go ahead, except in the case of TLS startup
1941 on connection, where outputting anything now upsets the clients and tends to
1942 make them disconnect. We need to have an explicit fflush() here, to force out
1943 the response. Other smtp_printf() calls do not need it, because in non-TLS
1944 mode, the fflush() happens when smtp_getc() is called. */
1946 SSL_set_session_id_context(server_ssl
, sid_ctx
, Ustrlen(sid_ctx
));
1947 if (!tls_in
.on_connect
)
1949 smtp_printf("220 TLS go ahead\r\n");
1953 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1954 that the OpenSSL library doesn't. */
1956 SSL_set_wfd(server_ssl
, fileno(smtp_out
));
1957 SSL_set_rfd(server_ssl
, fileno(smtp_in
));
1958 SSL_set_accept_state(server_ssl
);
1960 DEBUG(D_tls
) debug_printf("Calling SSL_accept\n");
1962 sigalrm_seen
= FALSE
;
1963 if (smtp_receive_timeout
> 0) alarm(smtp_receive_timeout
);
1964 rc
= SSL_accept(server_ssl
);
1969 tls_error(US
"SSL_accept", NULL
, sigalrm_seen
? US
"timed out" : NULL
);
1970 if (ERR_get_error() == 0)
1971 log_write(0, LOG_MAIN
,
1972 "TLS client disconnected cleanly (rejected our certificate?)");
1976 DEBUG(D_tls
) debug_printf("SSL_accept was successful\n");
1978 /* TLS has been set up. Adjust the input functions to read via TLS,
1979 and initialize things. */
1981 peer_cert(server_ssl
, &tls_in
, peerdn
, sizeof(peerdn
));
1983 construct_cipher_name(server_ssl
, cipherbuf
, sizeof(cipherbuf
), &tls_in
.bits
);
1984 tls_in
.cipher
= cipherbuf
;
1989 if (SSL_get_shared_ciphers(server_ssl
, CS buf
, sizeof(buf
)) != NULL
)
1990 debug_printf("Shared ciphers: %s\n", buf
);
1993 /* Record the certificate we presented */
1995 X509
* crt
= SSL_get_certificate(server_ssl
);
1996 tls_in
.ourcert
= crt
? X509_dup(crt
) : NULL
;
1999 /* Only used by the server-side tls (tls_in), including tls_getc.
2000 Client-side (tls_out) reads (seem to?) go via
2001 smtp_read_response()/ip_recv().
2002 Hence no need to duplicate for _in and _out.
2004 ssl_xfer_buffer
= store_malloc(ssl_xfer_buffer_size
);
2005 ssl_xfer_buffer_lwm
= ssl_xfer_buffer_hwm
= 0;
2006 ssl_xfer_eof
= ssl_xfer_error
= 0;
2008 receive_getc
= tls_getc
;
2009 receive_get_cache
= tls_get_cache
;
2010 receive_ungetc
= tls_ungetc
;
2011 receive_feof
= tls_feof
;
2012 receive_ferror
= tls_ferror
;
2013 receive_smtp_buffered
= tls_smtp_buffered
;
2015 tls_in
.active
= fileno(smtp_out
);
2023 tls_client_basic_ctx_init(SSL_CTX
* ctx
,
2024 host_item
* host
, smtp_transport_options_block
* ob
, tls_ext_ctx_cb
* cbinfo
2028 /* stick to the old behaviour for compatibility if tls_verify_certificates is
2029 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
2030 the specified host patterns if one of them is defined */
2032 if ( ( !ob
->tls_verify_hosts
2033 && (!ob
->tls_try_verify_hosts
|| !*ob
->tls_try_verify_hosts
)
2035 || (verify_check_given_host(&ob
->tls_verify_hosts
, host
) == OK
)
2037 client_verify_optional
= FALSE
;
2038 else if (verify_check_given_host(&ob
->tls_try_verify_hosts
, host
) == OK
)
2039 client_verify_optional
= TRUE
;
2043 if ((rc
= setup_certs(ctx
, ob
->tls_verify_certificates
,
2044 ob
->tls_crl
, host
, client_verify_optional
, verify_callback_client
)) != OK
)
2047 if (verify_check_given_host(&ob
->tls_verify_cert_hostnames
, host
) == OK
)
2049 cbinfo
->verify_cert_hostnames
=
2051 string_domain_utf8_to_alabel(host
->name
, NULL
);
2055 DEBUG(D_tls
) debug_printf("Cert hostname to check: \"%s\"\n",
2056 cbinfo
->verify_cert_hostnames
);
2062 #ifdef EXPERIMENTAL_DANE
2064 dane_tlsa_load(SSL
* ssl
, host_item
* host
, dns_answer
* dnsa
)
2068 const char * hostnames
[2] = { CS host
->name
, NULL
};
2071 if (DANESSL_init(ssl
, NULL
, hostnames
) != 1)
2072 return tls_error(US
"hostnames load", host
, NULL
);
2074 for (rr
= dns_next_rr(dnsa
, &dnss
, RESET_ANSWERS
);
2076 rr
= dns_next_rr(dnsa
, &dnss
, RESET_NEXT
)
2077 ) if (rr
->type
== T_TLSA
)
2079 const uschar
* p
= rr
->data
;
2080 uint8_t usage
, selector
, mtype
;
2081 const char * mdname
;
2085 /* Only DANE-TA(2) and DANE-EE(3) are supported */
2086 if (usage
!= 2 && usage
!= 3) continue;
2093 default: continue; /* Only match-types 0, 1, 2 are supported */
2094 case 0: mdname
= NULL
; break;
2095 case 1: mdname
= "sha256"; break;
2096 case 2: mdname
= "sha512"; break;
2100 switch (DANESSL_add_tlsa(ssl
, usage
, selector
, mdname
, p
, rr
->size
- 3))
2103 return tls_error(US
"tlsa load", host
, NULL
);
2104 case 0: /* action not taken */
2108 tls_out
.tlsa_usage
|= 1<<usage
;
2114 log_write(0, LOG_MAIN
, "DANE error: No usable TLSA records");
2117 #endif /*EXPERIMENTAL_DANE*/
2121 /*************************************************
2122 * Start a TLS session in a client *
2123 *************************************************/
2125 /* Called from the smtp transport after STARTTLS has been accepted.
2128 fd the fd of the connection
2129 host connected host (for messages)
2130 addr the first address
2131 tb transport (always smtp)
2132 tlsa_dnsa tlsa lookup, if DANE, else null
2134 Returns: OK on success
2135 FAIL otherwise - note that tls_error() will not give DEFER
2136 because this is not a server
2140 tls_client_start(int fd
, host_item
*host
, address_item
*addr
,
2141 transport_instance
*tb
2142 #ifdef EXPERIMENTAL_DANE
2143 , dns_answer
* tlsa_dnsa
2147 smtp_transport_options_block
* ob
=
2148 (smtp_transport_options_block
*)tb
->options_block
;
2149 static uschar peerdn
[256];
2150 uschar
* expciphers
;
2152 static uschar cipherbuf
[256];
2154 #ifndef DISABLE_OCSP
2155 BOOL request_ocsp
= FALSE
;
2156 BOOL require_ocsp
= FALSE
;
2159 #ifdef EXPERIMENTAL_DANE
2160 tls_out
.tlsa_usage
= 0;
2163 #ifndef DISABLE_OCSP
2165 # ifdef EXPERIMENTAL_DANE
2167 && ob
->hosts_request_ocsp
[0] == '*'
2168 && ob
->hosts_request_ocsp
[1] == '\0'
2171 /* Unchanged from default. Use a safer one under DANE */
2172 request_ocsp
= TRUE
;
2173 ob
->hosts_request_ocsp
= US
"${if or { {= {0}{$tls_out_tlsa_usage}} "
2174 " {= {4}{$tls_out_tlsa_usage}} } "
2180 verify_check_given_host(&ob
->hosts_require_ocsp
, host
) == OK
))
2181 request_ocsp
= TRUE
;
2183 # ifdef EXPERIMENTAL_DANE
2187 verify_check_given_host(&ob
->hosts_request_ocsp
, host
) == OK
;
2191 rc
= tls_init(&client_ctx
, host
, NULL
,
2192 ob
->tls_certificate
, ob
->tls_privatekey
,
2193 #ifndef DISABLE_OCSP
2194 (void *)(long)request_ocsp
,
2196 addr
, &client_static_cbinfo
);
2197 if (rc
!= OK
) return rc
;
2199 tls_out
.certificate_verified
= FALSE
;
2200 client_verify_callback_called
= FALSE
;
2202 if (!expand_check(ob
->tls_require_ciphers
, US
"tls_require_ciphers",
2206 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2207 are separated by underscores. So that I can use either form in my tests, and
2208 also for general convenience, we turn underscores into hyphens here. */
2210 if (expciphers
!= NULL
)
2212 uschar
*s
= expciphers
;
2213 while (*s
!= 0) { if (*s
== '_') *s
= '-'; s
++; }
2214 DEBUG(D_tls
) debug_printf("required ciphers: %s\n", expciphers
);
2215 if (!SSL_CTX_set_cipher_list(client_ctx
, CS expciphers
))
2216 return tls_error(US
"SSL_CTX_set_cipher_list", host
, NULL
);
2219 #ifdef EXPERIMENTAL_DANE
2222 SSL_CTX_set_verify(client_ctx
,
2223 SSL_VERIFY_PEER
| SSL_VERIFY_FAIL_IF_NO_PEER_CERT
,
2224 verify_callback_client_dane
);
2226 if (!DANESSL_library_init())
2227 return tls_error(US
"library init", host
, NULL
);
2228 if (DANESSL_CTX_init(client_ctx
) <= 0)
2229 return tls_error(US
"context init", host
, NULL
);
2235 if ((rc
= tls_client_basic_ctx_init(client_ctx
, host
, ob
, client_static_cbinfo
))
2239 if ((client_ssl
= SSL_new(client_ctx
)) == NULL
)
2240 return tls_error(US
"SSL_new", host
, NULL
);
2241 SSL_set_session_id_context(client_ssl
, sid_ctx
, Ustrlen(sid_ctx
));
2242 SSL_set_fd(client_ssl
, fd
);
2243 SSL_set_connect_state(client_ssl
);
2247 if (!expand_check(ob
->tls_sni
, US
"tls_sni", &tls_out
.sni
))
2249 if (tls_out
.sni
== NULL
)
2251 DEBUG(D_tls
) debug_printf("Setting TLS SNI forced to fail, not sending\n");
2253 else if (!Ustrlen(tls_out
.sni
))
2257 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2258 DEBUG(D_tls
) debug_printf("Setting TLS SNI \"%s\"\n", tls_out
.sni
);
2259 SSL_set_tlsext_host_name(client_ssl
, tls_out
.sni
);
2261 log_write(0, LOG_MAIN
, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
2267 #ifdef EXPERIMENTAL_DANE
2269 if ((rc
= dane_tlsa_load(client_ssl
, host
, tlsa_dnsa
)) != OK
)
2273 #ifndef DISABLE_OCSP
2274 /* Request certificate status at connection-time. If the server
2275 does OCSP stapling we will get the callback (set in tls_init()) */
2276 # ifdef EXPERIMENTAL_DANE
2280 if ( ((s
= ob
->hosts_require_ocsp
) && Ustrstr(s
, US
"tls_out_tlsa_usage"))
2281 || ((s
= ob
->hosts_request_ocsp
) && Ustrstr(s
, US
"tls_out_tlsa_usage"))
2283 { /* Re-eval now $tls_out_tlsa_usage is populated. If
2284 this means we avoid the OCSP request, we wasted the setup
2285 cost in tls_init(). */
2286 require_ocsp
= verify_check_given_host(&ob
->hosts_require_ocsp
, host
) == OK
;
2287 request_ocsp
= require_ocsp
2288 || verify_check_given_host(&ob
->hosts_request_ocsp
, host
) == OK
;
2295 SSL_set_tlsext_status_type(client_ssl
, TLSEXT_STATUSTYPE_ocsp
);
2296 client_static_cbinfo
->u_ocsp
.client
.verify_required
= require_ocsp
;
2297 tls_out
.ocsp
= OCSP_NOT_RESP
;
2301 #ifndef DISABLE_EVENT
2302 client_static_cbinfo
->event_action
= tb
->event_action
;
2305 /* There doesn't seem to be a built-in timeout on connection. */
2307 DEBUG(D_tls
) debug_printf("Calling SSL_connect\n");
2308 sigalrm_seen
= FALSE
;
2309 alarm(ob
->command_timeout
);
2310 rc
= SSL_connect(client_ssl
);
2313 #ifdef EXPERIMENTAL_DANE
2315 DANESSL_cleanup(client_ssl
);
2319 return tls_error(US
"SSL_connect", host
, sigalrm_seen
? US
"timed out" : NULL
);
2321 DEBUG(D_tls
) debug_printf("SSL_connect succeeded\n");
2323 peer_cert(client_ssl
, &tls_out
, peerdn
, sizeof(peerdn
));
2325 construct_cipher_name(client_ssl
, cipherbuf
, sizeof(cipherbuf
), &tls_out
.bits
);
2326 tls_out
.cipher
= cipherbuf
;
2328 /* Record the certificate we presented */
2330 X509
* crt
= SSL_get_certificate(client_ssl
);
2331 tls_out
.ourcert
= crt
? X509_dup(crt
) : NULL
;
2334 tls_out
.active
= fd
;
2342 /*************************************************
2343 * TLS version of getc *
2344 *************************************************/
2346 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2347 it refills the buffer via the SSL reading function.
2350 Returns: the next character or EOF
2352 Only used by the server-side TLS.
2358 if (ssl_xfer_buffer_lwm
>= ssl_xfer_buffer_hwm
)
2363 DEBUG(D_tls
) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl
,
2364 ssl_xfer_buffer
, ssl_xfer_buffer_size
);
2366 if (smtp_receive_timeout
> 0) alarm(smtp_receive_timeout
);
2367 inbytes
= SSL_read(server_ssl
, CS ssl_xfer_buffer
, ssl_xfer_buffer_size
);
2368 error
= SSL_get_error(server_ssl
, inbytes
);
2371 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2372 closed down, not that the socket itself has been closed down. Revert to
2373 non-SSL handling. */
2375 if (error
== SSL_ERROR_ZERO_RETURN
)
2377 DEBUG(D_tls
) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2379 receive_getc
= smtp_getc
;
2380 receive_get_cache
= smtp_get_cache
;
2381 receive_ungetc
= smtp_ungetc
;
2382 receive_feof
= smtp_feof
;
2383 receive_ferror
= smtp_ferror
;
2384 receive_smtp_buffered
= smtp_buffered
;
2386 SSL_free(server_ssl
);
2390 tls_in
.cipher
= NULL
;
2391 tls_in
.peerdn
= NULL
;
2397 /* Handle genuine errors */
2399 else if (error
== SSL_ERROR_SSL
)
2401 ERR_error_string(ERR_get_error(), ssl_errstring
);
2402 log_write(0, LOG_MAIN
, "TLS error (SSL_read): %s", ssl_errstring
);
2407 else if (error
!= SSL_ERROR_NONE
)
2409 DEBUG(D_tls
) debug_printf("Got SSL error %d\n", error
);
2414 #ifndef DISABLE_DKIM
2415 dkim_exim_verify_feed(ssl_xfer_buffer
, inbytes
);
2417 ssl_xfer_buffer_hwm
= inbytes
;
2418 ssl_xfer_buffer_lwm
= 0;
2421 /* Something in the buffer; return next uschar */
2423 return ssl_xfer_buffer
[ssl_xfer_buffer_lwm
++];
2429 #ifndef DISABLE_DKIM
2430 int n
= ssl_xfer_buffer_hwm
- ssl_xfer_buffer_lwm
;
2432 dkim_exim_verify_feed(ssl_xfer_buffer
+ssl_xfer_buffer_lwm
, n
);
2438 /*************************************************
2439 * Read bytes from TLS channel *
2440 *************************************************/
2447 Returns: the number of bytes read
2448 -1 after a failed read
2450 Only used by the client-side TLS.
2454 tls_read(BOOL is_server
, uschar
*buff
, size_t len
)
2456 SSL
*ssl
= is_server
? server_ssl
: client_ssl
;
2460 DEBUG(D_tls
) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl
,
2461 buff
, (unsigned int)len
);
2463 inbytes
= SSL_read(ssl
, CS buff
, len
);
2464 error
= SSL_get_error(ssl
, inbytes
);
2466 if (error
== SSL_ERROR_ZERO_RETURN
)
2468 DEBUG(D_tls
) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2471 else if (error
!= SSL_ERROR_NONE
)
2483 /*************************************************
2484 * Write bytes down TLS channel *
2485 *************************************************/
2489 is_server channel specifier
2493 Returns: the number of bytes after a successful write,
2494 -1 after a failed write
2496 Used by both server-side and client-side TLS.
2500 tls_write(BOOL is_server
, const uschar
*buff
, size_t len
)
2505 SSL
*ssl
= is_server
? server_ssl
: client_ssl
;
2507 DEBUG(D_tls
) debug_printf("tls_do_write(%p, %d)\n", buff
, left
);
2510 DEBUG(D_tls
) debug_printf("SSL_write(SSL, %p, %d)\n", buff
, left
);
2511 outbytes
= SSL_write(ssl
, CS buff
, left
);
2512 error
= SSL_get_error(ssl
, outbytes
);
2513 DEBUG(D_tls
) debug_printf("outbytes=%d error=%d\n", outbytes
, error
);
2517 ERR_error_string(ERR_get_error(), ssl_errstring
);
2518 log_write(0, LOG_MAIN
, "TLS error (SSL_write): %s", ssl_errstring
);
2521 case SSL_ERROR_NONE
:
2526 case SSL_ERROR_ZERO_RETURN
:
2527 log_write(0, LOG_MAIN
, "SSL channel closed on write");
2530 case SSL_ERROR_SYSCALL
:
2531 log_write(0, LOG_MAIN
, "SSL_write: (from %s) syscall: %s",
2532 sender_fullhost
? sender_fullhost
: US
"<unknown>",
2537 log_write(0, LOG_MAIN
, "SSL_write error %d", error
);
2546 /*************************************************
2547 * Close down a TLS session *
2548 *************************************************/
2550 /* This is also called from within a delivery subprocess forked from the
2551 daemon, to shut down the TLS library, without actually doing a shutdown (which
2552 would tamper with the SSL session in the parent process).
2554 Arguments: TRUE if SSL_shutdown is to be called
2557 Used by both server-side and client-side TLS.
2561 tls_close(BOOL is_server
, BOOL shutdown
)
2563 SSL
**sslp
= is_server
? &server_ssl
: &client_ssl
;
2564 int *fdp
= is_server
? &tls_in
.active
: &tls_out
.active
;
2566 if (*fdp
< 0) return; /* TLS was not active */
2570 DEBUG(D_tls
) debug_printf("tls_close(): shutting down SSL\n");
2571 SSL_shutdown(*sslp
);
2583 /*************************************************
2584 * Let tls_require_ciphers be checked at startup *
2585 *************************************************/
2587 /* The tls_require_ciphers option, if set, must be something which the
2590 Returns: NULL on success, or error message
2594 tls_validate_require_cipher(void)
2597 uschar
*s
, *expciphers
, *err
;
2599 /* this duplicates from tls_init(), we need a better "init just global
2600 state, for no specific purpose" singleton function of our own */
2602 SSL_load_error_strings();
2603 OpenSSL_add_ssl_algorithms();
2604 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2605 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2606 list of available digests. */
2607 EVP_add_digest(EVP_sha256());
2610 if (!(tls_require_ciphers
&& *tls_require_ciphers
))
2613 if (!expand_check(tls_require_ciphers
, US
"tls_require_ciphers", &expciphers
))
2614 return US
"failed to expand tls_require_ciphers";
2616 if (!(expciphers
&& *expciphers
))
2619 /* normalisation ripped from above */
2621 while (*s
!= 0) { if (*s
== '_') *s
= '-'; s
++; }
2625 ctx
= SSL_CTX_new(SSLv23_server_method());
2628 ERR_error_string(ERR_get_error(), ssl_errstring
);
2629 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring
);
2633 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers
);
2635 if (!SSL_CTX_set_cipher_list(ctx
, CS expciphers
))
2637 ERR_error_string(ERR_get_error(), ssl_errstring
);
2638 err
= string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers
);
2649 /*************************************************
2650 * Report the library versions. *
2651 *************************************************/
2653 /* There have historically been some issues with binary compatibility in
2654 OpenSSL libraries; if Exim (like many other applications) is built against
2655 one version of OpenSSL but the run-time linker picks up another version,
2656 it can result in serious failures, including crashing with a SIGSEGV. So
2657 report the version found by the compiler and the run-time version.
2659 Note: some OS vendors backport security fixes without changing the version
2660 number/string, and the version date remains unchanged. The _build_ date
2661 will change, so we can more usefully assist with version diagnosis by also
2662 reporting the build date.
2664 Arguments: a FILE* to print the results to
2669 tls_version_report(FILE *f
)
2671 fprintf(f
, "Library version: OpenSSL: Compile: %s\n"
2674 OPENSSL_VERSION_TEXT
,
2675 SSLeay_version(SSLEAY_VERSION
),
2676 SSLeay_version(SSLEAY_BUILT_ON
));
2677 /* third line is 38 characters for the %s and the line is 73 chars long;
2678 the OpenSSL output includes a "built on: " prefix already. */
2684 /*************************************************
2685 * Random number generation *
2686 *************************************************/
2688 /* Pseudo-random number generation. The result is not expected to be
2689 cryptographically strong but not so weak that someone will shoot themselves
2690 in the foot using it as a nonce in input in some email header scheme or
2691 whatever weirdness they'll twist this into. The result should handle fork()
2692 and avoid repeating sequences. OpenSSL handles that for us.
2696 Returns a random number in range [0, max-1]
2700 vaguely_random_number(int max
)
2704 static pid_t pidlast
= 0;
2707 uschar smallbuf
[sizeof(r
)];
2713 if (pidnow
!= pidlast
)
2715 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2716 is unique for each thread", this doesn't apparently apply across processes,
2717 so our own warning from vaguely_random_number_fallback() applies here too.
2718 Fix per PostgreSQL. */
2724 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2728 gettimeofday(&r
.tv
, NULL
);
2731 RAND_seed((uschar
*)(&r
), sizeof(r
));
2733 /* We're after pseudo-random, not random; if we still don't have enough data
2734 in the internal PRNG then our options are limited. We could sleep and hope
2735 for entropy to come along (prayer technique) but if the system is so depleted
2736 in the first place then something is likely to just keep taking it. Instead,
2737 we'll just take whatever little bit of pseudo-random we can still manage to
2740 needed_len
= sizeof(r
);
2741 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2742 asked for a number less than 10. */
2743 for (r
= max
, i
= 0; r
; ++i
)
2749 #ifdef EXIM_HAVE_RAND_PSEUDO
2750 /* We do not care if crypto-strong */
2751 i
= RAND_pseudo_bytes(smallbuf
, needed_len
);
2753 i
= RAND_bytes(smallbuf
, needed_len
);
2759 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2760 return vaguely_random_number_fallback(max
);
2764 for (p
= smallbuf
; needed_len
; --needed_len
, ++p
)
2770 /* We don't particularly care about weighted results; if someone wants
2771 smooth distribution and cares enough then they should submit a patch then. */
2778 /*************************************************
2779 * OpenSSL option parse *
2780 *************************************************/
2782 /* Parse one option for tls_openssl_options_parse below
2785 name one option name
2786 value place to store a value for it
2787 Returns success or failure in parsing
2790 struct exim_openssl_option
{
2794 /* We could use a macro to expand, but we need the ifdef and not all the
2795 options document which version they were introduced in. Policylet: include
2796 all options unless explicitly for DTLS, let the administrator choose which
2799 This list is current as of:
2801 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2803 static struct exim_openssl_option exim_openssl_options
[] = {
2804 /* KEEP SORTED ALPHABETICALLY! */
2806 { US
"all", SSL_OP_ALL
},
2808 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
2809 { US
"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
},
2811 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
2812 { US
"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE
},
2814 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
2815 { US
"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
},
2817 #ifdef SSL_OP_EPHEMERAL_RSA
2818 { US
"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA
},
2820 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
2821 { US
"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT
},
2823 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
2824 { US
"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
},
2826 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
2827 { US
"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG
},
2829 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
2830 { US
"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING
},
2832 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
2833 { US
"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG
},
2835 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
2836 { US
"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
},
2838 #ifdef SSL_OP_NO_COMPRESSION
2839 { US
"no_compression", SSL_OP_NO_COMPRESSION
},
2841 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
2842 { US
"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
},
2844 #ifdef SSL_OP_NO_SSLv2
2845 { US
"no_sslv2", SSL_OP_NO_SSLv2
},
2847 #ifdef SSL_OP_NO_SSLv3
2848 { US
"no_sslv3", SSL_OP_NO_SSLv3
},
2850 #ifdef SSL_OP_NO_TICKET
2851 { US
"no_ticket", SSL_OP_NO_TICKET
},
2853 #ifdef SSL_OP_NO_TLSv1
2854 { US
"no_tlsv1", SSL_OP_NO_TLSv1
},
2856 #ifdef SSL_OP_NO_TLSv1_1
2857 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
2858 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2859 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2861 { US
"no_tlsv1_1", SSL_OP_NO_TLSv1_1
},
2864 #ifdef SSL_OP_NO_TLSv1_2
2865 { US
"no_tlsv1_2", SSL_OP_NO_TLSv1_2
},
2867 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2868 { US
"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG
},
2870 #ifdef SSL_OP_SINGLE_DH_USE
2871 { US
"single_dh_use", SSL_OP_SINGLE_DH_USE
},
2873 #ifdef SSL_OP_SINGLE_ECDH_USE
2874 { US
"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE
},
2876 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
2877 { US
"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG
},
2879 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
2880 { US
"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
},
2882 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
2883 { US
"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG
},
2885 #ifdef SSL_OP_TLS_D5_BUG
2886 { US
"tls_d5_bug", SSL_OP_TLS_D5_BUG
},
2888 #ifdef SSL_OP_TLS_ROLLBACK_BUG
2889 { US
"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG
},
2892 static int exim_openssl_options_size
=
2893 sizeof(exim_openssl_options
)/sizeof(struct exim_openssl_option
);
2897 tls_openssl_one_option_parse(uschar
*name
, long *value
)
2900 int last
= exim_openssl_options_size
;
2901 while (last
> first
)
2903 int middle
= (first
+ last
)/2;
2904 int c
= Ustrcmp(name
, exim_openssl_options
[middle
].name
);
2907 *value
= exim_openssl_options
[middle
].value
;
2921 /*************************************************
2922 * OpenSSL option parsing logic *
2923 *************************************************/
2925 /* OpenSSL has a number of compatibility options which an administrator might
2926 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2927 we look like log_selector.
2930 option_spec the administrator-supplied string of options
2931 results ptr to long storage for the options bitmap
2932 Returns success or failure
2936 tls_openssl_options_parse(uschar
*option_spec
, long *results
)
2941 BOOL adding
, item_parsed
;
2944 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
2945 * from default because it increases BEAST susceptibility. */
2946 #ifdef SSL_OP_NO_SSLv2
2947 result
|= SSL_OP_NO_SSLv2
;
2949 #ifdef SSL_OP_SINGLE_DH_USE
2950 result
|= SSL_OP_SINGLE_DH_USE
;
2953 if (option_spec
== NULL
)
2959 for (s
=option_spec
; *s
!= '\0'; /**/)
2961 while (isspace(*s
)) ++s
;
2964 if (*s
!= '+' && *s
!= '-')
2966 DEBUG(D_tls
) debug_printf("malformed openssl option setting: "
2967 "+ or - expected but found \"%s\"\n", s
);
2970 adding
= *s
++ == '+';
2971 for (end
= s
; (*end
!= '\0') && !isspace(*end
); ++end
) /**/ ;
2974 item_parsed
= tls_openssl_one_option_parse(s
, &item
);
2978 DEBUG(D_tls
) debug_printf("openssl option setting unrecognised: \"%s\"\n", s
);
2981 DEBUG(D_tls
) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2982 adding
? "adding" : "removing", result
, item
, s
);
2996 /* End of tls-openssl.c */