1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2014 */
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>
26 # include <openssl/ocsp.h>
28 #ifdef EXPERIMENTAL_DANE
34 # define EXIM_OCSP_SKEW_SECONDS (300L)
35 # define EXIM_OCSP_MAX_AGE (-1L)
38 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
39 # define EXIM_HAVE_OPENSSL_TLSEXT
41 #if OPENSSL_VERSION_NUMBER >= 0x010100000L
42 # define EXIM_HAVE_OPENSSL_CHECKHOST
44 #if OPENSSL_VERSION_NUMBER >= 0x010000000L \
45 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
46 # define EXIM_HAVE_OPENSSL_CHECKHOST
49 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
50 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
54 /* Structure for collecting random data for seeding. */
56 typedef struct randstuff
{
61 /* Local static variables */
63 static BOOL client_verify_callback_called
= FALSE
;
64 static BOOL server_verify_callback_called
= FALSE
;
65 static const uschar
*sid_ctx
= US
"exim";
67 /* We have three different contexts to care about.
69 Simple case: client, `client_ctx`
70 As a client, we can be doing a callout or cut-through delivery while receiving
71 a message. So we have a client context, which should have options initialised
72 from the SMTP Transport.
75 There are two cases: with and without ServerNameIndication from the client.
76 Given TLS SNI, we can be using different keys, certs and various other
77 configuration settings, because they're re-expanded with $tls_sni set. This
78 allows vhosting with TLS. This SNI is sent in the handshake.
79 A client might not send SNI, so we need a fallback, and an initial setup too.
80 So as a server, we start out using `server_ctx`.
81 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
82 `server_sni` from `server_ctx` and then initialise settings by re-expanding
86 static SSL_CTX
*client_ctx
= NULL
;
87 static SSL_CTX
*server_ctx
= NULL
;
88 static SSL
*client_ssl
= NULL
;
89 static SSL
*server_ssl
= NULL
;
91 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
92 static SSL_CTX
*server_sni
= NULL
;
95 static char ssl_errstring
[256];
97 static int ssl_session_timeout
= 200;
98 static BOOL client_verify_optional
= FALSE
;
99 static BOOL server_verify_optional
= FALSE
;
101 static BOOL reexpand_tls_files_for_sni
= FALSE
;
104 typedef struct tls_ext_ctx_cb
{
112 uschar
*file_expanded
;
113 OCSP_RESPONSE
*response
;
116 X509_STORE
*verify_store
; /* non-null if status requested */
117 BOOL verify_required
;
122 /* these are cached from first expand */
123 uschar
*server_cipher_list
;
124 /* only passed down to tls_error: */
127 #ifdef EXPERIMENTAL_CERTNAMES
128 uschar
* verify_cert_hostnames
;
130 #ifdef EXPERIMENTAL_EVENT
131 uschar
* event_action
;
135 /* should figure out a cleanup of API to handle state preserved per
136 implementation, for various reasons, which can be void * in the APIs.
137 For now, we hack around it. */
138 tls_ext_ctx_cb
*client_static_cbinfo
= NULL
;
139 tls_ext_ctx_cb
*server_static_cbinfo
= NULL
;
142 setup_certs(SSL_CTX
*sctx
, uschar
*certs
, uschar
*crl
, host_item
*host
, BOOL optional
,
143 int (*cert_vfy_cb
)(int, X509_STORE_CTX
*) );
146 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
147 static int tls_servername_cb(SSL
*s
, int *ad ARG_UNUSED
, void *arg
);
150 static int tls_server_stapling_cb(SSL
*s
, void *arg
);
154 /*************************************************
156 *************************************************/
158 /* Called from lots of places when errors occur before actually starting to do
159 the TLS handshake, that is, while the session is still in clear. Always returns
160 DEFER for a server and FAIL for a client so that most calls can use "return
161 tls_error(...)" to do this processing and then give an appropriate return. A
162 single function is used for both server and client, because it is called from
163 some shared functions.
166 prefix text to include in the logged error
167 host NULL if setting up a server;
168 the connected host if setting up a client
169 msg error message or NULL if we should ask OpenSSL
171 Returns: OK/DEFER/FAIL
175 tls_error(uschar
*prefix
, host_item
*host
, uschar
*msg
)
179 ERR_error_string(ERR_get_error(), ssl_errstring
);
180 msg
= (uschar
*)ssl_errstring
;
185 log_write(0, LOG_MAIN
, "H=%s [%s] TLS error on connection (%s): %s",
186 host
->name
, host
->address
, prefix
, msg
);
191 uschar
*conn_info
= smtp_get_connection_info();
192 if (Ustrncmp(conn_info
, US
"SMTP ", 5) == 0)
194 /* I'd like to get separated H= here, but too hard for now */
195 log_write(0, LOG_MAIN
, "TLS error on %s (%s): %s",
196 conn_info
, prefix
, msg
);
203 /*************************************************
204 * Callback to generate RSA key *
205 *************************************************/
213 Returns: pointer to generated key
217 rsa_callback(SSL
*s
, int export
, int keylength
)
220 export
= export
; /* Shut picky compilers up */
221 DEBUG(D_tls
) debug_printf("Generating %d bit RSA key...\n", keylength
);
222 rsa_key
= RSA_generate_key(keylength
, RSA_F4
, NULL
, NULL
);
225 ERR_error_string(ERR_get_error(), ssl_errstring
);
226 log_write(0, LOG_MAIN
|LOG_PANIC
, "TLS error (RSA_generate_key): %s",
238 x509_store_dump_cert_s_names(X509_STORE * store)
240 STACK_OF(X509_OBJECT) * roots= store->objs;
242 static uschar name[256];
244 for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
246 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
247 if(tmp_obj->type == X509_LU_X509)
249 X509 * current_cert= tmp_obj->data.x509;
250 X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name));
251 debug_printf(" %s\n", name);
259 /*************************************************
260 * Callback for verification *
261 *************************************************/
263 /* The SSL library does certificate verification if set up to do so. This
264 callback has the current yes/no state is in "state". If verification succeeded,
265 we set up the tls_peerdn string. If verification failed, what happens depends
266 on whether the client is required to present a verifiable certificate or not.
268 If verification is optional, we change the state to yes, but still log the
269 verification error. For some reason (it really would help to have proper
270 documentation of OpenSSL), this callback function then gets called again, this
271 time with state = 1. In fact, that's useful, because we can set up the peerdn
272 value, but we must take care not to set the private verified flag on the second
275 Note: this function is not called if the client fails to present a certificate
276 when asked. We get here only if a certificate has been received. Handling of
277 optional verification for this case is done when requesting SSL to verify, by
278 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
280 May be called multiple times for different issues with a certificate, even
281 for a given "depth" in the certificate chain.
284 state current yes/no state as 1/0
285 x509ctx certificate information.
286 client TRUE for client startup, FALSE for server startup
288 Returns: 1 if verified, 0 if not
292 verify_callback(int state
, X509_STORE_CTX
*x509ctx
,
293 tls_support
*tlsp
, BOOL
*calledp
, BOOL
*optionalp
)
295 X509
* cert
= X509_STORE_CTX_get_current_cert(x509ctx
);
296 int depth
= X509_STORE_CTX_get_error_depth(x509ctx
);
297 static uschar txt
[256];
298 #ifdef EXPERIMENTAL_EVENT
303 X509_NAME_oneline(X509_get_subject_name(cert
), CS txt
, sizeof(txt
));
307 log_write(0, LOG_MAIN
, "SSL verify error: depth=%d error=%s cert=%s",
309 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx
)),
314 tlsp
->peercert
= X509_dup(cert
);
315 return 0; /* reject */
317 DEBUG(D_tls
) debug_printf("SSL verify failure overridden (host in "
318 "tls_try_verify_hosts)\n");
323 DEBUG(D_tls
) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth
, txt
);
325 if (tlsp
== &tls_out
&& client_static_cbinfo
->u_ocsp
.client
.verify_store
)
326 { /* client, wanting stapling */
327 /* Add the server cert's signing chain as the one
328 for the verification of the OCSP stapled information. */
330 if (!X509_STORE_add_cert(client_static_cbinfo
->u_ocsp
.client
.verify_store
,
335 #ifdef EXPERIMENTAL_EVENT
336 ev
= tlsp
== &tls_out
? client_static_cbinfo
->event_action
: event_action
;
339 tlsp
->peercert
= X509_dup(cert
);
340 if ((yield
= event_raise(ev
, US
"tls:cert", string_sprintf("%d", depth
))))
342 log_write(0, LOG_MAIN
, "SSL verify denied by event-action: "
343 "depth=%d cert=%s: %s", depth
, txt
, yield
);
346 return 0; /* reject */
347 DEBUG(D_tls
) debug_printf("Event-action verify failure overridden "
348 "(host in tls_try_verify_hosts)\n");
350 X509_free(tlsp
->peercert
);
351 tlsp
->peercert
= NULL
;
357 #ifdef EXPERIMENTAL_CERTNAMES
358 uschar
* verify_cert_hostnames
;
362 tlsp
->peercert
= X509_dup(cert
);
364 #ifdef EXPERIMENTAL_CERTNAMES
365 if ( tlsp
== &tls_out
366 && ((verify_cert_hostnames
= client_static_cbinfo
->verify_cert_hostnames
)))
367 /* client, wanting hostname check */
369 # if EXIM_HAVE_OPENSSL_CHECKHOST
370 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
371 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
375 uschar
* list
= verify_cert_hostnames
;
378 while ((name
= string_nextinlist(&list
, &sep
, NULL
, 0)))
379 if ((rc
= X509_check_host(cert
, name
, 0,
380 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
)))
384 log_write(0, LOG_MAIN
, "SSL verify error: internal error\n");
391 log_write(0, LOG_MAIN
,
392 "SSL verify error: certificate name mismatch: \"%s\"\n", txt
);
395 return 0; /* reject */
396 DEBUG(D_tls
) debug_printf("SSL verify failure overridden (host in "
397 "tls_try_verify_hosts)\n");
401 if (!tls_is_name_for_cert(verify_cert_hostnames
, cert
))
403 log_write(0, LOG_MAIN
,
404 "SSL verify error: certificate name mismatch: \"%s\"\n", txt
);
407 return 0; /* reject */
408 DEBUG(D_tls
) debug_printf("SSL verify failure overridden (host in "
409 "tls_try_verify_hosts)\n");
412 #endif /*EXPERIMENTAL_CERTNAMES*/
414 #ifdef EXPERIMENTAL_EVENT
415 ev
= tlsp
== &tls_out
? client_static_cbinfo
->event_action
: event_action
;
417 if ((yield
= event_raise(ev
, US
"tls:cert", US
"0")))
419 log_write(0, LOG_MAIN
, "SSL verify denied by event-action: "
420 "depth=0 cert=%s: %s", txt
, yield
);
423 return 0; /* reject */
424 DEBUG(D_tls
) debug_printf("Event-action verify failure overridden "
425 "(host in tls_try_verify_hosts)\n");
429 DEBUG(D_tls
) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
430 *calledp
? "" : " authenticated", txt
);
431 if (!*calledp
) tlsp
->certificate_verified
= TRUE
;
435 return 1; /* accept, at least for this level */
439 verify_callback_client(int state
, X509_STORE_CTX
*x509ctx
)
441 return verify_callback(state
, x509ctx
, &tls_out
, &client_verify_callback_called
, &client_verify_optional
);
445 verify_callback_server(int state
, X509_STORE_CTX
*x509ctx
)
447 return verify_callback(state
, x509ctx
, &tls_in
, &server_verify_callback_called
, &server_verify_optional
);
451 #ifdef EXPERIMENTAL_DANE
453 /* This gets called *by* the dane library verify callback, which interposes
457 verify_callback_client_dane(int state
, X509_STORE_CTX
* x509ctx
)
459 X509
* cert
= X509_STORE_CTX_get_current_cert(x509ctx
);
460 static uschar txt
[256];
461 #ifdef EXPERIMENTAL_EVENT
462 int depth
= X509_STORE_CTX_get_error_depth(x509ctx
);
466 X509_NAME_oneline(X509_get_subject_name(cert
), CS txt
, sizeof(txt
));
468 DEBUG(D_tls
) debug_printf("verify_callback_client_dane: %s\n", txt
);
469 tls_out
.peerdn
= txt
;
470 tls_out
.peercert
= X509_dup(cert
);
472 #ifdef EXPERIMENTAL_EVENT
473 if (client_static_cbinfo
->event_action
)
475 if ((yield
= event_raise(client_static_cbinfo
->event_action
,
476 US
"tls:cert", string_sprintf("%d", depth
))))
478 log_write(0, LOG_MAIN
, "DANE verify denied by event-action: "
479 "depth=%d cert=%s: %s", depth
, txt
, yield
);
480 tls_out
.certificate_verified
= FALSE
;
481 return 0; /* reject */
485 X509_free(tls_out
.peercert
);
486 tls_out
.peercert
= NULL
;
492 tls_out
.dane_verified
=
493 tls_out
.certificate_verified
= TRUE
;
497 #endif /*EXPERIMENTAL_DANE*/
500 /*************************************************
501 * Information callback *
502 *************************************************/
504 /* The SSL library functions call this from time to time to indicate what they
505 are doing. We copy the string to the debugging output when TLS debugging has
517 info_callback(SSL
*s
, int where
, int ret
)
521 DEBUG(D_tls
) debug_printf("SSL info: %s\n", SSL_state_string_long(s
));
526 /*************************************************
527 * Initialize for DH *
528 *************************************************/
530 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
533 dhparam DH parameter file or fixed parameter identity string
534 host connected host, if client; NULL if server
536 Returns: TRUE if OK (nothing to set up, or setup worked)
540 init_dh(SSL_CTX
*sctx
, uschar
*dhparam
, host_item
*host
)
547 if (!expand_check(dhparam
, US
"tls_dhparam", &dhexpanded
))
550 if (!dhexpanded
|| !*dhexpanded
)
551 bio
= BIO_new_mem_buf(CS
std_dh_prime_default(), -1);
552 else if (dhexpanded
[0] == '/')
554 if (!(bio
= BIO_new_file(CS dhexpanded
, "r")))
556 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded
),
557 host
, US
strerror(errno
));
563 if (Ustrcmp(dhexpanded
, "none") == 0)
565 DEBUG(D_tls
) debug_printf("Requested no DH parameters.\n");
569 if (!(pem
= std_dh_prime_named(dhexpanded
)))
571 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded
),
572 host
, US
strerror(errno
));
575 bio
= BIO_new_mem_buf(CS pem
, -1);
578 if (!(dh
= PEM_read_bio_DHparams(bio
, NULL
, NULL
, NULL
)))
581 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded
),
586 /* Even if it is larger, we silently return success rather than cause things
587 * to fail out, so that a too-large DH will not knock out all TLS; it's a
588 * debatable choice. */
589 if ((8*DH_size(dh
)) > tls_dh_max_bits
)
592 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
593 8*DH_size(dh
), tls_dh_max_bits
);
597 SSL_CTX_set_tmp_dh(sctx
, dh
);
599 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
600 dhexpanded
? dhexpanded
: US
"default", 8*DH_size(dh
));
613 /*************************************************
614 * Load OCSP information into state *
615 *************************************************/
617 /* Called to load the server OCSP response from the given file into memory, once
618 caller has determined this is needed. Checks validity. Debugs a message
621 ASSUMES: single response, for single cert.
624 sctx the SSL_CTX* to update
625 cbinfo various parts of session state
626 expanded the filename putatively holding an OCSP response
631 ocsp_load_response(SSL_CTX
*sctx
, tls_ext_ctx_cb
*cbinfo
, const uschar
*expanded
)
635 OCSP_BASICRESP
*basic_response
;
636 OCSP_SINGLERESP
*single_response
;
637 ASN1_GENERALIZEDTIME
*rev
, *thisupd
, *nextupd
;
639 unsigned long verify_flags
;
640 int status
, reason
, i
;
642 cbinfo
->u_ocsp
.server
.file_expanded
= string_copy(expanded
);
643 if (cbinfo
->u_ocsp
.server
.response
)
645 OCSP_RESPONSE_free(cbinfo
->u_ocsp
.server
.response
);
646 cbinfo
->u_ocsp
.server
.response
= NULL
;
649 bio
= BIO_new_file(CS cbinfo
->u_ocsp
.server
.file_expanded
, "rb");
652 DEBUG(D_tls
) debug_printf("Failed to open OCSP response file \"%s\"\n",
653 cbinfo
->u_ocsp
.server
.file_expanded
);
657 resp
= d2i_OCSP_RESPONSE_bio(bio
, NULL
);
661 DEBUG(D_tls
) debug_printf("Error reading OCSP response.\n");
665 status
= OCSP_response_status(resp
);
666 if (status
!= OCSP_RESPONSE_STATUS_SUCCESSFUL
)
668 DEBUG(D_tls
) debug_printf("OCSP response not valid: %s (%d)\n",
669 OCSP_response_status_str(status
), status
);
673 basic_response
= OCSP_response_get1_basic(resp
);
677 debug_printf("OCSP response parse error: unable to extract basic response.\n");
681 store
= SSL_CTX_get_cert_store(sctx
);
682 verify_flags
= OCSP_NOVERIFY
; /* check sigs, but not purpose */
684 /* May need to expose ability to adjust those flags?
685 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
686 OCSP_TRUSTOTHER OCSP_NOINTERN */
688 i
= OCSP_basic_verify(basic_response
, NULL
, store
, verify_flags
);
692 ERR_error_string(ERR_get_error(), ssl_errstring
);
693 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring
);
698 /* Here's the simplifying assumption: there's only one response, for the
699 one certificate we use, and nothing for anything else in a chain. If this
700 proves false, we need to extract a cert id from our issued cert
701 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
702 right cert in the stack and then calls OCSP_single_get0_status()).
704 I'm hoping to avoid reworking a bunch more of how we handle state here. */
705 single_response
= OCSP_resp_get0(basic_response
, 0);
706 if (!single_response
)
709 debug_printf("Unable to get first response from OCSP basic response.\n");
713 status
= OCSP_single_get0_status(single_response
, &reason
, &rev
, &thisupd
, &nextupd
);
714 if (status
!= V_OCSP_CERTSTATUS_GOOD
)
716 DEBUG(D_tls
) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
717 OCSP_cert_status_str(status
), status
,
718 OCSP_crl_reason_str(reason
), reason
);
722 if (!OCSP_check_validity(thisupd
, nextupd
, EXIM_OCSP_SKEW_SECONDS
, EXIM_OCSP_MAX_AGE
))
724 DEBUG(D_tls
) debug_printf("OCSP status invalid times.\n");
729 cbinfo
->u_ocsp
.server
.response
= resp
;
733 if (running_in_test_harness
)
735 extern char ** environ
;
737 for (p
= USS environ
; *p
!= NULL
; p
++)
738 if (Ustrncmp(*p
, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
740 DEBUG(D_tls
) debug_printf("Supplying known bad OCSP response\n");
741 goto supply_response
;
746 #endif /*!DISABLE_OCSP*/
751 /*************************************************
752 * Expand key and cert file specs *
753 *************************************************/
755 /* Called once during tls_init and possibly again during TLS setup, for a
756 new context, if Server Name Indication was used and tls_sni was seen in
757 the certificate string.
760 sctx the SSL_CTX* to update
761 cbinfo various parts of session state
763 Returns: OK/DEFER/FAIL
767 tls_expand_session_files(SSL_CTX
*sctx
, tls_ext_ctx_cb
*cbinfo
)
771 if (cbinfo
->certificate
== NULL
)
774 if (Ustrstr(cbinfo
->certificate
, US
"tls_sni") ||
775 Ustrstr(cbinfo
->certificate
, US
"tls_in_sni") ||
776 Ustrstr(cbinfo
->certificate
, US
"tls_out_sni")
778 reexpand_tls_files_for_sni
= TRUE
;
780 if (!expand_check(cbinfo
->certificate
, US
"tls_certificate", &expanded
))
783 if (expanded
!= NULL
)
785 DEBUG(D_tls
) debug_printf("tls_certificate file %s\n", expanded
);
786 if (!SSL_CTX_use_certificate_chain_file(sctx
, CS expanded
))
787 return tls_error(string_sprintf(
788 "SSL_CTX_use_certificate_chain_file file=%s", expanded
),
792 if (cbinfo
->privatekey
!= NULL
&&
793 !expand_check(cbinfo
->privatekey
, US
"tls_privatekey", &expanded
))
796 /* If expansion was forced to fail, key_expanded will be NULL. If the result
797 of the expansion is an empty string, ignore it also, and assume the private
798 key is in the same file as the certificate. */
800 if (expanded
!= NULL
&& *expanded
!= 0)
802 DEBUG(D_tls
) debug_printf("tls_privatekey file %s\n", expanded
);
803 if (!SSL_CTX_use_PrivateKey_file(sctx
, CS expanded
, SSL_FILETYPE_PEM
))
804 return tls_error(string_sprintf(
805 "SSL_CTX_use_PrivateKey_file file=%s", expanded
), cbinfo
->host
, NULL
);
809 if (cbinfo
->is_server
&& cbinfo
->u_ocsp
.server
.file
!= NULL
)
811 if (!expand_check(cbinfo
->u_ocsp
.server
.file
, US
"tls_ocsp_file", &expanded
))
814 if (expanded
!= NULL
&& *expanded
!= 0)
816 DEBUG(D_tls
) debug_printf("tls_ocsp_file %s\n", expanded
);
817 if (cbinfo
->u_ocsp
.server
.file_expanded
&&
818 (Ustrcmp(expanded
, cbinfo
->u_ocsp
.server
.file_expanded
) == 0))
821 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
823 ocsp_load_response(sctx
, cbinfo
, expanded
);
835 /*************************************************
836 * Callback to handle SNI *
837 *************************************************/
839 /* Called when acting as server during the TLS session setup if a Server Name
840 Indication extension was sent by the client.
842 API documentation is OpenSSL s_server.c implementation.
845 s SSL* of the current session
846 ad unknown (part of OpenSSL API) (unused)
847 arg Callback of "our" registered data
849 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
852 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
854 tls_servername_cb(SSL
*s
, int *ad ARG_UNUSED
, void *arg
)
856 const char *servername
= SSL_get_servername(s
, TLSEXT_NAMETYPE_host_name
);
857 tls_ext_ctx_cb
*cbinfo
= (tls_ext_ctx_cb
*) arg
;
859 int old_pool
= store_pool
;
862 return SSL_TLSEXT_ERR_OK
;
864 DEBUG(D_tls
) debug_printf("Received TLS SNI \"%s\"%s\n", servername
,
865 reexpand_tls_files_for_sni
? "" : " (unused for certificate selection)");
867 /* Make the extension value available for expansion */
868 store_pool
= POOL_PERM
;
869 tls_in
.sni
= string_copy(US servername
);
870 store_pool
= old_pool
;
872 if (!reexpand_tls_files_for_sni
)
873 return SSL_TLSEXT_ERR_OK
;
875 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
876 not confident that memcpy wouldn't break some internal reference counting.
877 Especially since there's a references struct member, which would be off. */
879 if (!(server_sni
= SSL_CTX_new(SSLv23_server_method())))
881 ERR_error_string(ERR_get_error(), ssl_errstring
);
882 DEBUG(D_tls
) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring
);
883 return SSL_TLSEXT_ERR_NOACK
;
886 /* Not sure how many of these are actually needed, since SSL object
887 already exists. Might even need this selfsame callback, for reneg? */
889 SSL_CTX_set_info_callback(server_sni
, SSL_CTX_get_info_callback(server_ctx
));
890 SSL_CTX_set_mode(server_sni
, SSL_CTX_get_mode(server_ctx
));
891 SSL_CTX_set_options(server_sni
, SSL_CTX_get_options(server_ctx
));
892 SSL_CTX_set_timeout(server_sni
, SSL_CTX_get_timeout(server_ctx
));
893 SSL_CTX_set_tlsext_servername_callback(server_sni
, tls_servername_cb
);
894 SSL_CTX_set_tlsext_servername_arg(server_sni
, cbinfo
);
895 if (cbinfo
->server_cipher_list
)
896 SSL_CTX_set_cipher_list(server_sni
, CS cbinfo
->server_cipher_list
);
898 if (cbinfo
->u_ocsp
.server
.file
)
900 SSL_CTX_set_tlsext_status_cb(server_sni
, tls_server_stapling_cb
);
901 SSL_CTX_set_tlsext_status_arg(server_sni
, cbinfo
);
905 rc
= setup_certs(server_sni
, tls_verify_certificates
, tls_crl
, NULL
, FALSE
, verify_callback_server
);
906 if (rc
!= OK
) return SSL_TLSEXT_ERR_NOACK
;
908 /* do this after setup_certs, because this can require the certs for verifying
910 rc
= tls_expand_session_files(server_sni
, cbinfo
);
911 if (rc
!= OK
) return SSL_TLSEXT_ERR_NOACK
;
913 if (!init_dh(server_sni
, cbinfo
->dhparam
, NULL
))
914 return SSL_TLSEXT_ERR_NOACK
;
916 DEBUG(D_tls
) debug_printf("Switching SSL context.\n");
917 SSL_set_SSL_CTX(s
, server_sni
);
919 return SSL_TLSEXT_ERR_OK
;
921 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
928 /*************************************************
929 * Callback to handle OCSP Stapling *
930 *************************************************/
932 /* Called when acting as server during the TLS session setup if the client
933 requests OCSP information with a Certificate Status Request.
935 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
941 tls_server_stapling_cb(SSL
*s
, void *arg
)
943 const tls_ext_ctx_cb
*cbinfo
= (tls_ext_ctx_cb
*) arg
;
944 uschar
*response_der
;
945 int response_der_len
;
948 debug_printf("Received TLS status request (OCSP stapling); %s response.",
949 cbinfo
->u_ocsp
.server
.response
? "have" : "lack");
951 tls_in
.ocsp
= OCSP_NOT_RESP
;
952 if (!cbinfo
->u_ocsp
.server
.response
)
953 return SSL_TLSEXT_ERR_NOACK
;
956 response_der_len
= i2d_OCSP_RESPONSE(cbinfo
->u_ocsp
.server
.response
,
958 if (response_der_len
<= 0)
959 return SSL_TLSEXT_ERR_NOACK
;
961 SSL_set_tlsext_status_ocsp_resp(server_ssl
, response_der
, response_der_len
);
962 tls_in
.ocsp
= OCSP_VFIED
;
963 return SSL_TLSEXT_ERR_OK
;
968 time_print(BIO
* bp
, const char * str
, ASN1_GENERALIZEDTIME
* time
)
970 BIO_printf(bp
, "\t%s: ", str
);
971 ASN1_GENERALIZEDTIME_print(bp
, time
);
976 tls_client_stapling_cb(SSL
*s
, void *arg
)
978 tls_ext_ctx_cb
* cbinfo
= arg
;
979 const unsigned char * p
;
985 DEBUG(D_tls
) debug_printf("Received TLS status response (OCSP stapling):");
986 len
= SSL_get_tlsext_status_ocsp_resp(s
, &p
);
989 /* Expect this when we requested ocsp but got none */
990 if ( cbinfo
->u_ocsp
.client
.verify_required
991 && log_extra_selector
& LX_tls_cipher
)
992 log_write(0, LOG_MAIN
, "Received TLS status callback, null content");
994 DEBUG(D_tls
) debug_printf(" null\n");
995 return cbinfo
->u_ocsp
.client
.verify_required
? 0 : 1;
998 if(!(rsp
= d2i_OCSP_RESPONSE(NULL
, &p
, len
)))
1000 tls_out
.ocsp
= OCSP_FAILED
;
1001 if (log_extra_selector
& LX_tls_cipher
)
1002 log_write(0, LOG_MAIN
, "Received TLS cert status response, parse error");
1004 DEBUG(D_tls
) debug_printf(" parse error\n");
1008 if(!(bs
= OCSP_response_get1_basic(rsp
)))
1010 tls_out
.ocsp
= OCSP_FAILED
;
1011 if (log_extra_selector
& LX_tls_cipher
)
1012 log_write(0, LOG_MAIN
, "Received TLS cert status response, error parsing response");
1014 DEBUG(D_tls
) debug_printf(" error parsing response\n");
1015 OCSP_RESPONSE_free(rsp
);
1019 /* We'd check the nonce here if we'd put one in the request. */
1020 /* However that would defeat cacheability on the server so we don't. */
1022 /* This section of code reworked from OpenSSL apps source;
1023 The OpenSSL Project retains copyright:
1024 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1029 ASN1_GENERALIZEDTIME
*rev
, *thisupd
, *nextupd
;
1031 DEBUG(D_tls
) bp
= BIO_new_fp(stderr
, BIO_NOCLOSE
);
1033 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1035 /* Use the chain that verified the server cert to verify the stapled info */
1036 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1038 if ((i
= OCSP_basic_verify(bs
, NULL
,
1039 cbinfo
->u_ocsp
.client
.verify_store
, 0)) <= 0)
1041 tls_out
.ocsp
= OCSP_FAILED
;
1042 if (log_extra_selector
& LX_tls_cipher
)
1043 log_write(0, LOG_MAIN
, "Received TLS cert status response, itself unverifiable");
1044 BIO_printf(bp
, "OCSP response verify failure\n");
1045 ERR_print_errors(bp
);
1046 i
= cbinfo
->u_ocsp
.client
.verify_required
? 0 : 1;
1050 BIO_printf(bp
, "OCSP response well-formed and signed OK\n");
1053 STACK_OF(OCSP_SINGLERESP
) * sresp
= bs
->tbsResponseData
->responses
;
1054 OCSP_SINGLERESP
* single
;
1056 if (sk_OCSP_SINGLERESP_num(sresp
) != 1)
1058 tls_out
.ocsp
= OCSP_FAILED
;
1059 log_write(0, LOG_MAIN
, "OCSP stapling "
1060 "with multiple responses not handled");
1061 i
= cbinfo
->u_ocsp
.client
.verify_required
? 0 : 1;
1064 single
= OCSP_resp_get0(bs
, 0);
1065 status
= OCSP_single_get0_status(single
, &reason
, &rev
,
1066 &thisupd
, &nextupd
);
1069 DEBUG(D_tls
) time_print(bp
, "This OCSP Update", thisupd
);
1070 DEBUG(D_tls
) if(nextupd
) time_print(bp
, "Next OCSP Update", nextupd
);
1071 if (!OCSP_check_validity(thisupd
, nextupd
,
1072 EXIM_OCSP_SKEW_SECONDS
, EXIM_OCSP_MAX_AGE
))
1074 tls_out
.ocsp
= OCSP_FAILED
;
1075 DEBUG(D_tls
) ERR_print_errors(bp
);
1076 log_write(0, LOG_MAIN
, "Server OSCP dates invalid");
1077 i
= cbinfo
->u_ocsp
.client
.verify_required
? 0 : 1;
1081 DEBUG(D_tls
) BIO_printf(bp
, "Certificate status: %s\n",
1082 OCSP_cert_status_str(status
));
1085 case V_OCSP_CERTSTATUS_GOOD
:
1086 tls_out
.ocsp
= OCSP_VFIED
;
1089 case V_OCSP_CERTSTATUS_REVOKED
:
1090 tls_out
.ocsp
= OCSP_FAILED
;
1091 log_write(0, LOG_MAIN
, "Server certificate revoked%s%s",
1092 reason
!= -1 ? "; reason: " : "",
1093 reason
!= -1 ? OCSP_crl_reason_str(reason
) : "");
1094 DEBUG(D_tls
) time_print(bp
, "Revocation Time", rev
);
1095 i
= cbinfo
->u_ocsp
.client
.verify_required
? 0 : 1;
1098 tls_out
.ocsp
= OCSP_FAILED
;
1099 log_write(0, LOG_MAIN
,
1100 "Server certificate status unknown, in OCSP stapling");
1101 i
= cbinfo
->u_ocsp
.client
.verify_required
? 0 : 1;
1109 OCSP_RESPONSE_free(rsp
);
1112 #endif /*!DISABLE_OCSP*/
1115 /*************************************************
1116 * Initialize for TLS *
1117 *************************************************/
1119 /* Called from both server and client code, to do preliminary initialization
1120 of the library. We allocate and return a context structure.
1123 ctxp returned SSL context
1124 host connected host, if client; NULL if server
1125 dhparam DH parameter file
1126 certificate certificate file
1127 privatekey private key
1128 ocsp_file file of stapling info (server); flag for require ocsp (client)
1129 addr address if client; NULL if server (for some randomness)
1130 cbp place to put allocated callback context
1132 Returns: OK/DEFER/FAIL
1136 tls_init(SSL_CTX
**ctxp
, host_item
*host
, uschar
*dhparam
, uschar
*certificate
,
1138 #ifndef DISABLE_OCSP
1141 address_item
*addr
, tls_ext_ctx_cb
** cbp
)
1146 tls_ext_ctx_cb
* cbinfo
;
1148 cbinfo
= store_malloc(sizeof(tls_ext_ctx_cb
));
1149 cbinfo
->certificate
= certificate
;
1150 cbinfo
->privatekey
= privatekey
;
1151 #ifndef DISABLE_OCSP
1152 if ((cbinfo
->is_server
= host
==NULL
))
1154 cbinfo
->u_ocsp
.server
.file
= ocsp_file
;
1155 cbinfo
->u_ocsp
.server
.file_expanded
= NULL
;
1156 cbinfo
->u_ocsp
.server
.response
= NULL
;
1159 cbinfo
->u_ocsp
.client
.verify_store
= NULL
;
1161 cbinfo
->dhparam
= dhparam
;
1162 cbinfo
->server_cipher_list
= NULL
;
1163 cbinfo
->host
= host
;
1164 #ifdef EXPERIMENTAL_EVENT
1165 cbinfo
->event_action
= NULL
;
1168 SSL_load_error_strings(); /* basic set up */
1169 OpenSSL_add_ssl_algorithms();
1171 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1172 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1173 list of available digests. */
1174 EVP_add_digest(EVP_sha256());
1177 /* Create a context.
1178 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1179 negotiation in the different methods; as far as I can tell, the only
1180 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1181 when OpenSSL is built without SSLv2 support.
1182 By disabling with openssl_options, we can let admins re-enable with the
1185 *ctxp
= SSL_CTX_new((host
== NULL
)?
1186 SSLv23_server_method() : SSLv23_client_method());
1188 if (*ctxp
== NULL
) return tls_error(US
"SSL_CTX_new", host
, NULL
);
1190 /* It turns out that we need to seed the random number generator this early in
1191 order to get the full complement of ciphers to work. It took me roughly a day
1192 of work to discover this by experiment.
1194 On systems that have /dev/urandom, SSL may automatically seed itself from
1195 there. Otherwise, we have to make something up as best we can. Double check
1201 gettimeofday(&r
.tv
, NULL
);
1204 RAND_seed((uschar
*)(&r
), sizeof(r
));
1205 RAND_seed((uschar
*)big_buffer
, big_buffer_size
);
1206 if (addr
!= NULL
) RAND_seed((uschar
*)addr
, sizeof(addr
));
1209 return tls_error(US
"RAND_status", host
,
1210 US
"unable to seed random number generator");
1213 /* Set up the information callback, which outputs if debugging is at a suitable
1216 SSL_CTX_set_info_callback(*ctxp
, (void (*)())info_callback
);
1218 /* Automatically re-try reads/writes after renegotiation. */
1219 (void) SSL_CTX_set_mode(*ctxp
, SSL_MODE_AUTO_RETRY
);
1221 /* Apply administrator-supplied work-arounds.
1222 Historically we applied just one requested option,
1223 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1224 moved to an administrator-controlled list of options to specify and
1225 grandfathered in the first one as the default value for "openssl_options".
1227 No OpenSSL version number checks: the options we accept depend upon the
1228 availability of the option value macros from OpenSSL. */
1230 okay
= tls_openssl_options_parse(openssl_options
, &init_options
);
1232 return tls_error(US
"openssl_options parsing failed", host
, NULL
);
1236 DEBUG(D_tls
) debug_printf("setting SSL CTX options: %#lx\n", init_options
);
1237 if (!(SSL_CTX_set_options(*ctxp
, init_options
)))
1238 return tls_error(string_sprintf(
1239 "SSL_CTX_set_option(%#lx)", init_options
), host
, NULL
);
1242 DEBUG(D_tls
) debug_printf("no SSL CTX options to set\n");
1244 /* Initialize with DH parameters if supplied */
1246 if (!init_dh(*ctxp
, dhparam
, host
)) return DEFER
;
1248 /* Set up certificate and key (and perhaps OCSP info) */
1250 rc
= tls_expand_session_files(*ctxp
, cbinfo
);
1251 if (rc
!= OK
) return rc
;
1253 /* If we need to handle SNI, do so */
1254 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1255 if (host
== NULL
) /* server */
1257 # ifndef DISABLE_OCSP
1258 /* We check u_ocsp.server.file, not server.response, because we care about if
1259 the option exists, not what the current expansion might be, as SNI might
1260 change the certificate and OCSP file in use between now and the time the
1261 callback is invoked. */
1262 if (cbinfo
->u_ocsp
.server
.file
)
1264 SSL_CTX_set_tlsext_status_cb(server_ctx
, tls_server_stapling_cb
);
1265 SSL_CTX_set_tlsext_status_arg(server_ctx
, cbinfo
);
1268 /* We always do this, so that $tls_sni is available even if not used in
1270 SSL_CTX_set_tlsext_servername_callback(*ctxp
, tls_servername_cb
);
1271 SSL_CTX_set_tlsext_servername_arg(*ctxp
, cbinfo
);
1273 # ifndef DISABLE_OCSP
1275 if(ocsp_file
) /* wanting stapling */
1277 if (!(cbinfo
->u_ocsp
.client
.verify_store
= X509_STORE_new()))
1279 DEBUG(D_tls
) debug_printf("failed to create store for stapling verify\n");
1282 SSL_CTX_set_tlsext_status_cb(*ctxp
, tls_client_stapling_cb
);
1283 SSL_CTX_set_tlsext_status_arg(*ctxp
, cbinfo
);
1288 #ifdef EXPERIMENTAL_CERTNAMES
1289 cbinfo
->verify_cert_hostnames
= NULL
;
1292 /* Set up the RSA callback */
1294 SSL_CTX_set_tmp_rsa_callback(*ctxp
, rsa_callback
);
1296 /* Finally, set the timeout, and we are done */
1298 SSL_CTX_set_timeout(*ctxp
, ssl_session_timeout
);
1299 DEBUG(D_tls
) debug_printf("Initialized TLS\n");
1309 /*************************************************
1310 * Get name of cipher in use *
1311 *************************************************/
1314 Argument: pointer to an SSL structure for the connection
1315 buffer to use for answer
1317 pointer to number of bits for cipher
1322 construct_cipher_name(SSL
*ssl
, uschar
*cipherbuf
, int bsize
, int *bits
)
1324 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1325 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1326 the accessor functions use const in the prototype. */
1327 const SSL_CIPHER
*c
;
1330 ver
= (const uschar
*)SSL_get_version(ssl
);
1332 c
= (const SSL_CIPHER
*) SSL_get_current_cipher(ssl
);
1333 SSL_CIPHER_get_bits(c
, bits
);
1335 string_format(cipherbuf
, bsize
, "%s:%s:%u", ver
,
1336 SSL_CIPHER_get_name(c
), *bits
);
1338 DEBUG(D_tls
) debug_printf("Cipher: %s\n", cipherbuf
);
1345 /*************************************************
1346 * Set up for verifying certificates *
1347 *************************************************/
1349 /* Called by both client and server startup
1352 sctx SSL_CTX* to initialise
1353 certs certs file or NULL
1354 crl CRL file or NULL
1355 host NULL in a server; the remote host in a client
1356 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1357 otherwise passed as FALSE
1358 cert_vfy_cb Callback function for certificate verification
1360 Returns: OK/DEFER/FAIL
1364 setup_certs(SSL_CTX
*sctx
, uschar
*certs
, uschar
*crl
, host_item
*host
, BOOL optional
,
1365 int (*cert_vfy_cb
)(int, X509_STORE_CTX
*) )
1367 uschar
*expcerts
, *expcrl
;
1369 if (!expand_check(certs
, US
"tls_verify_certificates", &expcerts
))
1372 if (expcerts
!= NULL
&& *expcerts
!= '\0')
1374 struct stat statbuf
;
1375 if (!SSL_CTX_set_default_verify_paths(sctx
))
1376 return tls_error(US
"SSL_CTX_set_default_verify_paths", host
, NULL
);
1378 if (Ustat(expcerts
, &statbuf
) < 0)
1380 log_write(0, LOG_MAIN
|LOG_PANIC
,
1381 "failed to stat %s for certificates", expcerts
);
1387 if ((statbuf
.st_mode
& S_IFMT
) == S_IFDIR
)
1388 { file
= NULL
; dir
= expcerts
; }
1390 { file
= expcerts
; dir
= NULL
; }
1392 /* If a certificate file is empty, the next function fails with an
1393 unhelpful error message. If we skip it, we get the correct behaviour (no
1394 certificates are recognized, but the error message is still misleading (it
1395 says no certificate was supplied.) But this is better. */
1397 if ((file
== NULL
|| statbuf
.st_size
> 0) &&
1398 !SSL_CTX_load_verify_locations(sctx
, CS file
, CS dir
))
1399 return tls_error(US
"SSL_CTX_load_verify_locations", host
, NULL
);
1401 /* Load the list of CAs for which we will accept certs, for sending
1402 to the client. This is only for the one-file tls_verify_certificates
1404 If a list isn't loaded into the server, but
1405 some verify locations are set, the server end appears to make
1406 a wildcard reqest for client certs.
1407 Meanwhile, the client library as deafult behaviour *ignores* the list
1408 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1409 Because of this, and that the dir variant is likely only used for
1410 the public-CA bundle (not for a private CA), not worth fixing.
1414 STACK_OF(X509_NAME
) * names
= SSL_load_client_CA_file(CS file
);
1415 DEBUG(D_tls
) debug_printf("Added %d certificate authorities.\n",
1416 sk_X509_NAME_num(names
));
1417 SSL_CTX_set_client_CA_list(sctx
, names
);
1421 /* Handle a certificate revocation list. */
1423 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1425 /* This bit of code is now the version supplied by Lars Mainka. (I have
1426 * merely reformatted it into the Exim code style.)
1428 * "From here I changed the code to add support for multiple crl's
1429 * in pem format in one file or to support hashed directory entries in
1430 * pem format instead of a file. This method now uses the library function
1431 * X509_STORE_load_locations to add the CRL location to the SSL context.
1432 * OpenSSL will then handle the verify against CA certs and CRLs by
1433 * itself in the verify callback." */
1435 if (!expand_check(crl
, US
"tls_crl", &expcrl
)) return DEFER
;
1436 if (expcrl
!= NULL
&& *expcrl
!= 0)
1438 struct stat statbufcrl
;
1439 if (Ustat(expcrl
, &statbufcrl
) < 0)
1441 log_write(0, LOG_MAIN
|LOG_PANIC
,
1442 "failed to stat %s for certificates revocation lists", expcrl
);
1447 /* is it a file or directory? */
1449 X509_STORE
*cvstore
= SSL_CTX_get_cert_store(sctx
);
1450 if ((statbufcrl
.st_mode
& S_IFMT
) == S_IFDIR
)
1454 DEBUG(D_tls
) debug_printf("SSL CRL value is a directory %s\n", dir
);
1460 DEBUG(D_tls
) debug_printf("SSL CRL value is a file %s\n", file
);
1462 if (X509_STORE_load_locations(cvstore
, CS file
, CS dir
) == 0)
1463 return tls_error(US
"X509_STORE_load_locations", host
, NULL
);
1465 /* setting the flags to check against the complete crl chain */
1467 X509_STORE_set_flags(cvstore
,
1468 X509_V_FLAG_CRL_CHECK
|X509_V_FLAG_CRL_CHECK_ALL
);
1472 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1474 /* If verification is optional, don't fail if no certificate */
1476 SSL_CTX_set_verify(sctx
,
1477 SSL_VERIFY_PEER
| (optional
? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT
),
1486 /*************************************************
1487 * Start a TLS session in a server *
1488 *************************************************/
1490 /* This is called when Exim is running as a server, after having received
1491 the STARTTLS command. It must respond to that command, and then negotiate
1495 require_ciphers allowed ciphers
1497 Returns: OK on success
1498 DEFER for errors before the start of the negotiation
1499 FAIL for errors during the negotation; the server can't
1504 tls_server_start(const uschar
*require_ciphers
)
1508 tls_ext_ctx_cb
*cbinfo
;
1509 static uschar cipherbuf
[256];
1511 /* Check for previous activation */
1513 if (tls_in
.active
>= 0)
1515 tls_error(US
"STARTTLS received after TLS started", NULL
, US
"");
1516 smtp_printf("554 Already in TLS\r\n");
1520 /* Initialize the SSL library. If it fails, it will already have logged
1523 rc
= tls_init(&server_ctx
, NULL
, tls_dhparam
, tls_certificate
, tls_privatekey
,
1524 #ifndef DISABLE_OCSP
1527 NULL
, &server_static_cbinfo
);
1528 if (rc
!= OK
) return rc
;
1529 cbinfo
= server_static_cbinfo
;
1531 if (!expand_check(require_ciphers
, US
"tls_require_ciphers", &expciphers
))
1534 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1535 were historically separated by underscores. So that I can use either form in my
1536 tests, and also for general convenience, we turn underscores into hyphens here.
1539 if (expciphers
!= NULL
)
1541 uschar
*s
= expciphers
;
1542 while (*s
!= 0) { if (*s
== '_') *s
= '-'; s
++; }
1543 DEBUG(D_tls
) debug_printf("required ciphers: %s\n", expciphers
);
1544 if (!SSL_CTX_set_cipher_list(server_ctx
, CS expciphers
))
1545 return tls_error(US
"SSL_CTX_set_cipher_list", NULL
, NULL
);
1546 cbinfo
->server_cipher_list
= expciphers
;
1549 /* If this is a host for which certificate verification is mandatory or
1550 optional, set up appropriately. */
1552 tls_in
.certificate_verified
= FALSE
;
1553 #ifdef EXPERIMENTAL_DANE
1554 tls_in
.dane_verified
= FALSE
;
1556 server_verify_callback_called
= FALSE
;
1558 if (verify_check_host(&tls_verify_hosts
) == OK
)
1560 rc
= setup_certs(server_ctx
, tls_verify_certificates
, tls_crl
, NULL
,
1561 FALSE
, verify_callback_server
);
1562 if (rc
!= OK
) return rc
;
1563 server_verify_optional
= FALSE
;
1565 else if (verify_check_host(&tls_try_verify_hosts
) == OK
)
1567 rc
= setup_certs(server_ctx
, tls_verify_certificates
, tls_crl
, NULL
,
1568 TRUE
, verify_callback_server
);
1569 if (rc
!= OK
) return rc
;
1570 server_verify_optional
= TRUE
;
1573 /* Prepare for new connection */
1575 if ((server_ssl
= SSL_new(server_ctx
)) == NULL
) return tls_error(US
"SSL_new", NULL
, NULL
);
1577 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1579 * With the SSL_clear(), we get strange interoperability bugs with
1580 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1581 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1583 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1584 * session shutdown. In this case, we have a brand new object and there's no
1585 * obvious reason to immediately clear it. I'm guessing that this was
1586 * originally added because of incomplete initialisation which the clear fixed,
1587 * in some historic release.
1590 /* Set context and tell client to go ahead, except in the case of TLS startup
1591 on connection, where outputting anything now upsets the clients and tends to
1592 make them disconnect. We need to have an explicit fflush() here, to force out
1593 the response. Other smtp_printf() calls do not need it, because in non-TLS
1594 mode, the fflush() happens when smtp_getc() is called. */
1596 SSL_set_session_id_context(server_ssl
, sid_ctx
, Ustrlen(sid_ctx
));
1597 if (!tls_in
.on_connect
)
1599 smtp_printf("220 TLS go ahead\r\n");
1603 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1604 that the OpenSSL library doesn't. */
1606 SSL_set_wfd(server_ssl
, fileno(smtp_out
));
1607 SSL_set_rfd(server_ssl
, fileno(smtp_in
));
1608 SSL_set_accept_state(server_ssl
);
1610 DEBUG(D_tls
) debug_printf("Calling SSL_accept\n");
1612 sigalrm_seen
= FALSE
;
1613 if (smtp_receive_timeout
> 0) alarm(smtp_receive_timeout
);
1614 rc
= SSL_accept(server_ssl
);
1619 tls_error(US
"SSL_accept", NULL
, sigalrm_seen
? US
"timed out" : NULL
);
1620 if (ERR_get_error() == 0)
1621 log_write(0, LOG_MAIN
,
1622 "TLS client disconnected cleanly (rejected our certificate?)");
1626 DEBUG(D_tls
) debug_printf("SSL_accept was successful\n");
1628 /* TLS has been set up. Adjust the input functions to read via TLS,
1629 and initialize things. */
1631 construct_cipher_name(server_ssl
, cipherbuf
, sizeof(cipherbuf
), &tls_in
.bits
);
1632 tls_in
.cipher
= cipherbuf
;
1637 if (SSL_get_shared_ciphers(server_ssl
, CS buf
, sizeof(buf
)) != NULL
)
1638 debug_printf("Shared ciphers: %s\n", buf
);
1641 /* Record the certificate we presented */
1643 X509
* crt
= SSL_get_certificate(server_ssl
);
1644 tls_in
.ourcert
= crt
? X509_dup(crt
) : NULL
;
1647 /* Only used by the server-side tls (tls_in), including tls_getc.
1648 Client-side (tls_out) reads (seem to?) go via
1649 smtp_read_response()/ip_recv().
1650 Hence no need to duplicate for _in and _out.
1652 ssl_xfer_buffer
= store_malloc(ssl_xfer_buffer_size
);
1653 ssl_xfer_buffer_lwm
= ssl_xfer_buffer_hwm
= 0;
1654 ssl_xfer_eof
= ssl_xfer_error
= 0;
1656 receive_getc
= tls_getc
;
1657 receive_ungetc
= tls_ungetc
;
1658 receive_feof
= tls_feof
;
1659 receive_ferror
= tls_ferror
;
1660 receive_smtp_buffered
= tls_smtp_buffered
;
1662 tls_in
.active
= fileno(smtp_out
);
1670 tls_client_basic_ctx_init(SSL_CTX
* ctx
,
1671 host_item
* host
, smtp_transport_options_block
* ob
1672 #ifdef EXPERIMENTAL_CERTNAMES
1673 , tls_ext_ctx_cb
* cbinfo
1678 /* stick to the old behaviour for compatibility if tls_verify_certificates is
1679 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
1680 the specified host patterns if one of them is defined */
1682 if ((!ob
->tls_verify_hosts
&& !ob
->tls_try_verify_hosts
) ||
1683 (verify_check_host(&ob
->tls_verify_hosts
) == OK
))
1685 if ((rc
= setup_certs(ctx
, ob
->tls_verify_certificates
,
1686 ob
->tls_crl
, host
, FALSE
, verify_callback_client
)) != OK
)
1688 client_verify_optional
= FALSE
;
1690 #ifdef EXPERIMENTAL_CERTNAMES
1691 if (ob
->tls_verify_cert_hostnames
)
1693 if (!expand_check(ob
->tls_verify_cert_hostnames
,
1694 US
"tls_verify_cert_hostnames",
1695 &cbinfo
->verify_cert_hostnames
))
1697 if (cbinfo
->verify_cert_hostnames
)
1698 DEBUG(D_tls
) debug_printf("Cert hostname to check: \"%s\"\n",
1699 cbinfo
->verify_cert_hostnames
);
1703 else if (verify_check_host(&ob
->tls_try_verify_hosts
) == OK
)
1705 if ((rc
= setup_certs(ctx
, ob
->tls_verify_certificates
,
1706 ob
->tls_crl
, host
, TRUE
, verify_callback_client
)) != OK
)
1708 client_verify_optional
= TRUE
;
1715 #ifdef EXPERIMENTAL_DANE
1717 dane_tlsa_load(SSL
* ssl
, host_item
* host
, dns_answer
* dnsa
)
1721 const char * hostnames
[2] = { CS host
->name
, NULL
};
1724 if (DANESSL_init(ssl
, NULL
, hostnames
) != 1)
1725 return tls_error(US
"hostnames load", host
, NULL
);
1727 for (rr
= dns_next_rr(dnsa
, &dnss
, RESET_ANSWERS
);
1729 rr
= dns_next_rr(dnsa
, &dnss
, RESET_NEXT
)
1730 ) if (rr
->type
== T_TLSA
)
1732 uschar
* p
= rr
->data
;
1733 uint8_t usage
, selector
, mtype
;
1734 const char * mdname
;
1738 /* Only DANE-TA(2) and DANE-EE(3) are supported */
1739 if (usage
!= 2 && usage
!= 3) continue;
1746 default: continue; /* Only match-types 0, 1, 2 are supported */
1747 case 0: mdname
= NULL
; break;
1748 case 1: mdname
= "sha256"; break;
1749 case 2: mdname
= "sha512"; break;
1753 switch (DANESSL_add_tlsa(ssl
, usage
, selector
, mdname
, p
, rr
->size
- 3))
1756 case 0: /* action not taken */
1757 return tls_error(US
"tlsa load", host
, NULL
);
1761 tls_out
.tlsa_usage
|= 1<<usage
;
1767 log_write(0, LOG_MAIN
, "DANE error: No usable TLSA records");
1770 #endif /*EXPERIMENTAL_DANE*/
1774 /*************************************************
1775 * Start a TLS session in a client *
1776 *************************************************/
1778 /* Called from the smtp transport after STARTTLS has been accepted.
1781 fd the fd of the connection
1782 host connected host (for messages)
1783 addr the first address
1784 tb transport (always smtp)
1785 tlsa_dnsa tlsa lookup, if DANE, else null
1787 Returns: OK on success
1788 FAIL otherwise - note that tls_error() will not give DEFER
1789 because this is not a server
1793 tls_client_start(int fd
, host_item
*host
, address_item
*addr
,
1794 transport_instance
*tb
1795 #ifdef EXPERIMENTAL_DANE
1796 , dns_answer
* tlsa_dnsa
1800 smtp_transport_options_block
* ob
=
1801 (smtp_transport_options_block
*)tb
->options_block
;
1802 static uschar txt
[256];
1803 uschar
* expciphers
;
1806 static uschar cipherbuf
[256];
1808 #ifndef DISABLE_OCSP
1809 BOOL request_ocsp
= FALSE
;
1810 BOOL require_ocsp
= FALSE
;
1813 #ifdef EXPERIMENTAL_DANE
1814 tls_out
.tlsa_usage
= 0;
1817 #ifndef DISABLE_OCSP
1819 # ifdef EXPERIMENTAL_DANE
1821 && ob
->hosts_request_ocsp
[0] == '*'
1822 && ob
->hosts_request_ocsp
[1] == '\0'
1825 /* Unchanged from default. Use a safer one under DANE */
1826 request_ocsp
= TRUE
;
1827 ob
->hosts_request_ocsp
= US
"${if or { {= {0}{$tls_out_tlsa_usage}} "
1828 " {= {4}{$tls_out_tlsa_usage}} } "
1833 if ((require_ocsp
= verify_check_this_host(&ob
->hosts_require_ocsp
,
1834 NULL
, host
->name
, host
->address
, NULL
) == OK
))
1835 request_ocsp
= TRUE
;
1837 # ifdef EXPERIMENTAL_DANE
1840 request_ocsp
= verify_check_this_host(&ob
->hosts_request_ocsp
,
1841 NULL
, host
->name
, host
->address
, NULL
) == OK
;
1845 rc
= tls_init(&client_ctx
, host
, NULL
,
1846 ob
->tls_certificate
, ob
->tls_privatekey
,
1847 #ifndef DISABLE_OCSP
1848 (void *)(long)request_ocsp
,
1850 addr
, &client_static_cbinfo
);
1851 if (rc
!= OK
) return rc
;
1853 tls_out
.certificate_verified
= FALSE
;
1854 client_verify_callback_called
= FALSE
;
1856 if (!expand_check(ob
->tls_require_ciphers
, US
"tls_require_ciphers",
1860 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1861 are separated by underscores. So that I can use either form in my tests, and
1862 also for general convenience, we turn underscores into hyphens here. */
1864 if (expciphers
!= NULL
)
1866 uschar
*s
= expciphers
;
1867 while (*s
!= 0) { if (*s
== '_') *s
= '-'; s
++; }
1868 DEBUG(D_tls
) debug_printf("required ciphers: %s\n", expciphers
);
1869 if (!SSL_CTX_set_cipher_list(client_ctx
, CS expciphers
))
1870 return tls_error(US
"SSL_CTX_set_cipher_list", host
, NULL
);
1873 #ifdef EXPERIMENTAL_DANE
1876 SSL_CTX_set_verify(client_ctx
, SSL_VERIFY_PEER
, verify_callback_client_dane
);
1878 if (!DANESSL_library_init())
1879 return tls_error(US
"library init", host
, NULL
);
1880 if (DANESSL_CTX_init(client_ctx
) <= 0)
1881 return tls_error(US
"context init", host
, NULL
);
1887 if ((rc
= tls_client_basic_ctx_init(client_ctx
, host
, ob
1888 #ifdef EXPERIMENTAL_CERTNAMES
1889 , client_static_cbinfo
1894 if ((client_ssl
= SSL_new(client_ctx
)) == NULL
)
1895 return tls_error(US
"SSL_new", host
, NULL
);
1896 SSL_set_session_id_context(client_ssl
, sid_ctx
, Ustrlen(sid_ctx
));
1897 SSL_set_fd(client_ssl
, fd
);
1898 SSL_set_connect_state(client_ssl
);
1902 if (!expand_check(ob
->tls_sni
, US
"tls_sni", &tls_out
.sni
))
1904 if (tls_out
.sni
== NULL
)
1906 DEBUG(D_tls
) debug_printf("Setting TLS SNI forced to fail, not sending\n");
1908 else if (!Ustrlen(tls_out
.sni
))
1912 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1913 DEBUG(D_tls
) debug_printf("Setting TLS SNI \"%s\"\n", tls_out
.sni
);
1914 SSL_set_tlsext_host_name(client_ssl
, tls_out
.sni
);
1917 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
1923 #ifdef EXPERIMENTAL_DANE
1925 if ((rc
= dane_tlsa_load(client_ssl
, host
, tlsa_dnsa
)) != OK
)
1929 #ifndef DISABLE_OCSP
1930 /* Request certificate status at connection-time. If the server
1931 does OCSP stapling we will get the callback (set in tls_init()) */
1932 # ifdef EXPERIMENTAL_DANE
1936 if ( ((s
= ob
->hosts_require_ocsp
) && Ustrstr(s
, US
"tls_out_tlsa_usage"))
1937 || ((s
= ob
->hosts_request_ocsp
) && Ustrstr(s
, US
"tls_out_tlsa_usage"))
1939 { /* Re-eval now $tls_out_tlsa_usage is populated. If
1940 this means we avoid the OCSP request, we wasted the setup
1941 cost in tls_init(). */
1942 require_ocsp
= verify_check_this_host(&ob
->hosts_require_ocsp
,
1943 NULL
, host
->name
, host
->address
, NULL
) == OK
;
1944 request_ocsp
= require_ocsp
? TRUE
1945 : verify_check_this_host(&ob
->hosts_request_ocsp
,
1946 NULL
, host
->name
, host
->address
, NULL
) == OK
;
1953 SSL_set_tlsext_status_type(client_ssl
, TLSEXT_STATUSTYPE_ocsp
);
1954 client_static_cbinfo
->u_ocsp
.client
.verify_required
= require_ocsp
;
1955 tls_out
.ocsp
= OCSP_NOT_RESP
;
1959 #ifdef EXPERIMENTAL_EVENT
1960 client_static_cbinfo
->event_action
= tb
->event_action
;
1963 /* There doesn't seem to be a built-in timeout on connection. */
1965 DEBUG(D_tls
) debug_printf("Calling SSL_connect\n");
1966 sigalrm_seen
= FALSE
;
1967 alarm(ob
->command_timeout
);
1968 rc
= SSL_connect(client_ssl
);
1971 #ifdef EXPERIMENTAL_DANE
1973 DANESSL_cleanup(client_ssl
);
1977 return tls_error(US
"SSL_connect", host
, sigalrm_seen
? US
"timed out" : NULL
);
1979 DEBUG(D_tls
) debug_printf("SSL_connect succeeded\n");
1981 /* Beware anonymous ciphers which lead to server_cert being NULL */
1982 /*XXX server_cert is never freed... use X509_free() */
1983 server_cert
= SSL_get_peer_certificate (client_ssl
);
1986 tls_out
.peerdn
= US
X509_NAME_oneline(X509_get_subject_name(server_cert
),
1987 CS txt
, sizeof(txt
));
1988 tls_out
.peerdn
= txt
; /*XXX a static buffer... */
1991 tls_out
.peerdn
= NULL
;
1993 construct_cipher_name(client_ssl
, cipherbuf
, sizeof(cipherbuf
), &tls_out
.bits
);
1994 tls_out
.cipher
= cipherbuf
;
1996 /* Record the certificate we presented */
1998 X509
* crt
= SSL_get_certificate(client_ssl
);
1999 tls_out
.ourcert
= crt
? X509_dup(crt
) : NULL
;
2002 tls_out
.active
= fd
;
2010 /*************************************************
2011 * TLS version of getc *
2012 *************************************************/
2014 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2015 it refills the buffer via the SSL reading function.
2018 Returns: the next character or EOF
2020 Only used by the server-side TLS.
2026 if (ssl_xfer_buffer_lwm
>= ssl_xfer_buffer_hwm
)
2031 DEBUG(D_tls
) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl
,
2032 ssl_xfer_buffer
, ssl_xfer_buffer_size
);
2034 if (smtp_receive_timeout
> 0) alarm(smtp_receive_timeout
);
2035 inbytes
= SSL_read(server_ssl
, CS ssl_xfer_buffer
, ssl_xfer_buffer_size
);
2036 error
= SSL_get_error(server_ssl
, inbytes
);
2039 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2040 closed down, not that the socket itself has been closed down. Revert to
2041 non-SSL handling. */
2043 if (error
== SSL_ERROR_ZERO_RETURN
)
2045 DEBUG(D_tls
) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2047 receive_getc
= smtp_getc
;
2048 receive_ungetc
= smtp_ungetc
;
2049 receive_feof
= smtp_feof
;
2050 receive_ferror
= smtp_ferror
;
2051 receive_smtp_buffered
= smtp_buffered
;
2053 SSL_free(server_ssl
);
2057 tls_in
.cipher
= NULL
;
2058 tls_in
.peerdn
= NULL
;
2064 /* Handle genuine errors */
2066 else if (error
== SSL_ERROR_SSL
)
2068 ERR_error_string(ERR_get_error(), ssl_errstring
);
2069 log_write(0, LOG_MAIN
, "TLS error (SSL_read): %s", ssl_errstring
);
2074 else if (error
!= SSL_ERROR_NONE
)
2076 DEBUG(D_tls
) debug_printf("Got SSL error %d\n", error
);
2081 #ifndef DISABLE_DKIM
2082 dkim_exim_verify_feed(ssl_xfer_buffer
, inbytes
);
2084 ssl_xfer_buffer_hwm
= inbytes
;
2085 ssl_xfer_buffer_lwm
= 0;
2088 /* Something in the buffer; return next uschar */
2090 return ssl_xfer_buffer
[ssl_xfer_buffer_lwm
++];
2095 /*************************************************
2096 * Read bytes from TLS channel *
2097 *************************************************/
2104 Returns: the number of bytes read
2105 -1 after a failed read
2107 Only used by the client-side TLS.
2111 tls_read(BOOL is_server
, uschar
*buff
, size_t len
)
2113 SSL
*ssl
= is_server
? server_ssl
: client_ssl
;
2117 DEBUG(D_tls
) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl
,
2118 buff
, (unsigned int)len
);
2120 inbytes
= SSL_read(ssl
, CS buff
, len
);
2121 error
= SSL_get_error(ssl
, inbytes
);
2123 if (error
== SSL_ERROR_ZERO_RETURN
)
2125 DEBUG(D_tls
) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2128 else if (error
!= SSL_ERROR_NONE
)
2140 /*************************************************
2141 * Write bytes down TLS channel *
2142 *************************************************/
2146 is_server channel specifier
2150 Returns: the number of bytes after a successful write,
2151 -1 after a failed write
2153 Used by both server-side and client-side TLS.
2157 tls_write(BOOL is_server
, const uschar
*buff
, size_t len
)
2162 SSL
*ssl
= is_server
? server_ssl
: client_ssl
;
2164 DEBUG(D_tls
) debug_printf("tls_do_write(%p, %d)\n", buff
, left
);
2167 DEBUG(D_tls
) debug_printf("SSL_write(SSL, %p, %d)\n", buff
, left
);
2168 outbytes
= SSL_write(ssl
, CS buff
, left
);
2169 error
= SSL_get_error(ssl
, outbytes
);
2170 DEBUG(D_tls
) debug_printf("outbytes=%d error=%d\n", outbytes
, error
);
2174 ERR_error_string(ERR_get_error(), ssl_errstring
);
2175 log_write(0, LOG_MAIN
, "TLS error (SSL_write): %s", ssl_errstring
);
2178 case SSL_ERROR_NONE
:
2183 case SSL_ERROR_ZERO_RETURN
:
2184 log_write(0, LOG_MAIN
, "SSL channel closed on write");
2187 case SSL_ERROR_SYSCALL
:
2188 log_write(0, LOG_MAIN
, "SSL_write: (from %s) syscall: %s",
2189 sender_fullhost
? sender_fullhost
: US
"<unknown>",
2193 log_write(0, LOG_MAIN
, "SSL_write error %d", error
);
2202 /*************************************************
2203 * Close down a TLS session *
2204 *************************************************/
2206 /* This is also called from within a delivery subprocess forked from the
2207 daemon, to shut down the TLS library, without actually doing a shutdown (which
2208 would tamper with the SSL session in the parent process).
2210 Arguments: TRUE if SSL_shutdown is to be called
2213 Used by both server-side and client-side TLS.
2217 tls_close(BOOL is_server
, BOOL shutdown
)
2219 SSL
**sslp
= is_server
? &server_ssl
: &client_ssl
;
2220 int *fdp
= is_server
? &tls_in
.active
: &tls_out
.active
;
2222 if (*fdp
< 0) return; /* TLS was not active */
2226 DEBUG(D_tls
) debug_printf("tls_close(): shutting down SSL\n");
2227 SSL_shutdown(*sslp
);
2239 /*************************************************
2240 * Let tls_require_ciphers be checked at startup *
2241 *************************************************/
2243 /* The tls_require_ciphers option, if set, must be something which the
2246 Returns: NULL on success, or error message
2250 tls_validate_require_cipher(void)
2253 uschar
*s
, *expciphers
, *err
;
2255 /* this duplicates from tls_init(), we need a better "init just global
2256 state, for no specific purpose" singleton function of our own */
2258 SSL_load_error_strings();
2259 OpenSSL_add_ssl_algorithms();
2260 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2261 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2262 list of available digests. */
2263 EVP_add_digest(EVP_sha256());
2266 if (!(tls_require_ciphers
&& *tls_require_ciphers
))
2269 if (!expand_check(tls_require_ciphers
, US
"tls_require_ciphers", &expciphers
))
2270 return US
"failed to expand tls_require_ciphers";
2272 if (!(expciphers
&& *expciphers
))
2275 /* normalisation ripped from above */
2277 while (*s
!= 0) { if (*s
== '_') *s
= '-'; s
++; }
2281 ctx
= SSL_CTX_new(SSLv23_server_method());
2284 ERR_error_string(ERR_get_error(), ssl_errstring
);
2285 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring
);
2289 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers
);
2291 if (!SSL_CTX_set_cipher_list(ctx
, CS expciphers
))
2293 ERR_error_string(ERR_get_error(), ssl_errstring
);
2294 err
= string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers
);
2305 /*************************************************
2306 * Report the library versions. *
2307 *************************************************/
2309 /* There have historically been some issues with binary compatibility in
2310 OpenSSL libraries; if Exim (like many other applications) is built against
2311 one version of OpenSSL but the run-time linker picks up another version,
2312 it can result in serious failures, including crashing with a SIGSEGV. So
2313 report the version found by the compiler and the run-time version.
2315 Note: some OS vendors backport security fixes without changing the version
2316 number/string, and the version date remains unchanged. The _build_ date
2317 will change, so we can more usefully assist with version diagnosis by also
2318 reporting the build date.
2320 Arguments: a FILE* to print the results to
2325 tls_version_report(FILE *f
)
2327 fprintf(f
, "Library version: OpenSSL: Compile: %s\n"
2330 OPENSSL_VERSION_TEXT
,
2331 SSLeay_version(SSLEAY_VERSION
),
2332 SSLeay_version(SSLEAY_BUILT_ON
));
2333 /* third line is 38 characters for the %s and the line is 73 chars long;
2334 the OpenSSL output includes a "built on: " prefix already. */
2340 /*************************************************
2341 * Random number generation *
2342 *************************************************/
2344 /* Pseudo-random number generation. The result is not expected to be
2345 cryptographically strong but not so weak that someone will shoot themselves
2346 in the foot using it as a nonce in input in some email header scheme or
2347 whatever weirdness they'll twist this into. The result should handle fork()
2348 and avoid repeating sequences. OpenSSL handles that for us.
2352 Returns a random number in range [0, max-1]
2356 vaguely_random_number(int max
)
2360 static pid_t pidlast
= 0;
2363 uschar smallbuf
[sizeof(r
)];
2369 if (pidnow
!= pidlast
)
2371 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2372 is unique for each thread", this doesn't apparently apply across processes,
2373 so our own warning from vaguely_random_number_fallback() applies here too.
2374 Fix per PostgreSQL. */
2380 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2384 gettimeofday(&r
.tv
, NULL
);
2387 RAND_seed((uschar
*)(&r
), sizeof(r
));
2389 /* We're after pseudo-random, not random; if we still don't have enough data
2390 in the internal PRNG then our options are limited. We could sleep and hope
2391 for entropy to come along (prayer technique) but if the system is so depleted
2392 in the first place then something is likely to just keep taking it. Instead,
2393 we'll just take whatever little bit of pseudo-random we can still manage to
2396 needed_len
= sizeof(r
);
2397 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2398 asked for a number less than 10. */
2399 for (r
= max
, i
= 0; r
; ++i
)
2405 /* We do not care if crypto-strong */
2406 i
= RAND_pseudo_bytes(smallbuf
, needed_len
);
2410 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2411 return vaguely_random_number_fallback(max
);
2415 for (p
= smallbuf
; needed_len
; --needed_len
, ++p
)
2421 /* We don't particularly care about weighted results; if someone wants
2422 smooth distribution and cares enough then they should submit a patch then. */
2429 /*************************************************
2430 * OpenSSL option parse *
2431 *************************************************/
2433 /* Parse one option for tls_openssl_options_parse below
2436 name one option name
2437 value place to store a value for it
2438 Returns success or failure in parsing
2441 struct exim_openssl_option
{
2445 /* We could use a macro to expand, but we need the ifdef and not all the
2446 options document which version they were introduced in. Policylet: include
2447 all options unless explicitly for DTLS, let the administrator choose which
2450 This list is current as of:
2452 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2454 static struct exim_openssl_option exim_openssl_options
[] = {
2455 /* KEEP SORTED ALPHABETICALLY! */
2457 { US
"all", SSL_OP_ALL
},
2459 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
2460 { US
"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
},
2462 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
2463 { US
"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE
},
2465 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
2466 { US
"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
},
2468 #ifdef SSL_OP_EPHEMERAL_RSA
2469 { US
"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA
},
2471 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
2472 { US
"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT
},
2474 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
2475 { US
"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
},
2477 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
2478 { US
"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG
},
2480 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
2481 { US
"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING
},
2483 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
2484 { US
"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG
},
2486 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
2487 { US
"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
},
2489 #ifdef SSL_OP_NO_COMPRESSION
2490 { US
"no_compression", SSL_OP_NO_COMPRESSION
},
2492 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
2493 { US
"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
},
2495 #ifdef SSL_OP_NO_SSLv2
2496 { US
"no_sslv2", SSL_OP_NO_SSLv2
},
2498 #ifdef SSL_OP_NO_SSLv3
2499 { US
"no_sslv3", SSL_OP_NO_SSLv3
},
2501 #ifdef SSL_OP_NO_TICKET
2502 { US
"no_ticket", SSL_OP_NO_TICKET
},
2504 #ifdef SSL_OP_NO_TLSv1
2505 { US
"no_tlsv1", SSL_OP_NO_TLSv1
},
2507 #ifdef SSL_OP_NO_TLSv1_1
2508 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
2509 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2510 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2512 { US
"no_tlsv1_1", SSL_OP_NO_TLSv1_1
},
2515 #ifdef SSL_OP_NO_TLSv1_2
2516 { US
"no_tlsv1_2", SSL_OP_NO_TLSv1_2
},
2518 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2519 { US
"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG
},
2521 #ifdef SSL_OP_SINGLE_DH_USE
2522 { US
"single_dh_use", SSL_OP_SINGLE_DH_USE
},
2524 #ifdef SSL_OP_SINGLE_ECDH_USE
2525 { US
"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE
},
2527 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
2528 { US
"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG
},
2530 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
2531 { US
"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
},
2533 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
2534 { US
"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG
},
2536 #ifdef SSL_OP_TLS_D5_BUG
2537 { US
"tls_d5_bug", SSL_OP_TLS_D5_BUG
},
2539 #ifdef SSL_OP_TLS_ROLLBACK_BUG
2540 { US
"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG
},
2543 static int exim_openssl_options_size
=
2544 sizeof(exim_openssl_options
)/sizeof(struct exim_openssl_option
);
2548 tls_openssl_one_option_parse(uschar
*name
, long *value
)
2551 int last
= exim_openssl_options_size
;
2552 while (last
> first
)
2554 int middle
= (first
+ last
)/2;
2555 int c
= Ustrcmp(name
, exim_openssl_options
[middle
].name
);
2558 *value
= exim_openssl_options
[middle
].value
;
2572 /*************************************************
2573 * OpenSSL option parsing logic *
2574 *************************************************/
2576 /* OpenSSL has a number of compatibility options which an administrator might
2577 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2578 we look like log_selector.
2581 option_spec the administrator-supplied string of options
2582 results ptr to long storage for the options bitmap
2583 Returns success or failure
2587 tls_openssl_options_parse(uschar
*option_spec
, long *results
)
2592 BOOL adding
, item_parsed
;
2595 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
2596 * from default because it increases BEAST susceptibility. */
2597 #ifdef SSL_OP_NO_SSLv2
2598 result
|= SSL_OP_NO_SSLv2
;
2601 if (option_spec
== NULL
)
2607 for (s
=option_spec
; *s
!= '\0'; /**/)
2609 while (isspace(*s
)) ++s
;
2612 if (*s
!= '+' && *s
!= '-')
2614 DEBUG(D_tls
) debug_printf("malformed openssl option setting: "
2615 "+ or - expected but found \"%s\"\n", s
);
2618 adding
= *s
++ == '+';
2619 for (end
= s
; (*end
!= '\0') && !isspace(*end
); ++end
) /**/ ;
2622 item_parsed
= tls_openssl_one_option_parse(s
, &item
);
2625 DEBUG(D_tls
) debug_printf("openssl option setting unrecognised: \"%s\"\n", s
);
2628 DEBUG(D_tls
) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2629 adding
? "adding" : "removing", result
, item
, s
);
2644 /* End of tls-openssl.c */