1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2012 */
6 /* See the file NOTICE for conditions of use and distribution. */
8 /* This module provides the TLS (aka SSL) support for Exim using the OpenSSL
9 library. It is #included into the tls.c file when that library is used. The
10 code herein is based on a patch that was originally contributed by Steve
11 Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara.
13 No cryptographic code is included in Exim. All this module does is to call
14 functions from the OpenSSL library. */
19 #include <openssl/lhash.h>
20 #include <openssl/ssl.h>
21 #include <openssl/err.h>
22 #include <openssl/rand.h>
23 #ifdef EXPERIMENTAL_OCSP
24 #include <openssl/ocsp.h>
27 #ifdef EXPERIMENTAL_OCSP
28 #define EXIM_OCSP_SKEW_SECONDS (300L)
29 #define EXIM_OCSP_MAX_AGE (-1L)
32 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
33 #define EXIM_HAVE_OPENSSL_TLSEXT
36 /* Structure for collecting random data for seeding. */
38 typedef struct randstuff
{
43 /* Local static variables */
45 static BOOL verify_callback_called
= FALSE
;
46 static const uschar
*sid_ctx
= US
"exim";
48 static SSL_CTX
*client_ctx
= NULL
;
49 static SSL_CTX
*server_ctx
= NULL
;
50 static SSL
*client_ssl
= NULL
;
51 static SSL
*server_ssl
= NULL
;
52 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
53 static SSL_CTX
*client_sni
= NULL
;
54 static SSL_CTX
*server_sni
= NULL
;
57 static char ssl_errstring
[256];
59 static int ssl_session_timeout
= 200;
60 static BOOL verify_optional
= FALSE
;
62 static BOOL reexpand_tls_files_for_sni
= FALSE
;
65 typedef struct tls_ext_ctx_cb
{
68 #ifdef EXPERIMENTAL_OCSP
70 uschar
*ocsp_file_expanded
;
71 OCSP_RESPONSE
*ocsp_response
;
74 /* these are cached from first expand */
75 uschar
*server_cipher_list
;
76 /* only passed down to tls_error: */
80 /* should figure out a cleanup of API to handle state preserved per
81 implementation, for various reasons, which can be void * in the APIs.
82 For now, we hack around it. */
83 tls_ext_ctx_cb
*client_static_cbinfo
= NULL
;
84 tls_ext_ctx_cb
*server_static_cbinfo
= NULL
;
87 setup_certs(SSL_CTX
*sctx
, uschar
*certs
, uschar
*crl
, host_item
*host
, BOOL optional
);
90 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
91 static int tls_servername_cb(SSL
*s
, int *ad ARG_UNUSED
, void *arg
);
93 #ifdef EXPERIMENTAL_OCSP
94 static int tls_stapling_cb(SSL
*s
, void *arg
);
98 /*************************************************
100 *************************************************/
102 /* Called from lots of places when errors occur before actually starting to do
103 the TLS handshake, that is, while the session is still in clear. Always returns
104 DEFER for a server and FAIL for a client so that most calls can use "return
105 tls_error(...)" to do this processing and then give an appropriate return. A
106 single function is used for both server and client, because it is called from
107 some shared functions.
110 prefix text to include in the logged error
111 host NULL if setting up a server;
112 the connected host if setting up a client
113 msg error message or NULL if we should ask OpenSSL
115 Returns: OK/DEFER/FAIL
119 tls_error(uschar
*prefix
, host_item
*host
, uschar
*msg
)
123 ERR_error_string(ERR_get_error(), ssl_errstring
);
124 msg
= (uschar
*)ssl_errstring
;
129 uschar
*conn_info
= smtp_get_connection_info();
130 if (Ustrncmp(conn_info
, US
"SMTP ", 5) == 0)
132 log_write(0, LOG_MAIN
, "TLS error on %s (%s): %s",
133 conn_info
, prefix
, msg
);
138 log_write(0, LOG_MAIN
, "TLS error on connection to %s [%s] (%s): %s",
139 host
->name
, host
->address
, prefix
, msg
);
146 /*************************************************
147 * Callback to generate RSA key *
148 *************************************************/
156 Returns: pointer to generated key
160 rsa_callback(SSL
*s
, int export
, int keylength
)
163 export
= export
; /* Shut picky compilers up */
164 DEBUG(D_tls
) debug_printf("Generating %d bit RSA key...\n", keylength
);
165 rsa_key
= RSA_generate_key(keylength
, RSA_F4
, NULL
, NULL
);
168 ERR_error_string(ERR_get_error(), ssl_errstring
);
169 log_write(0, LOG_MAIN
|LOG_PANIC
, "TLS error (RSA_generate_key): %s",
179 /*************************************************
180 * Callback for verification *
181 *************************************************/
183 /* The SSL library does certificate verification if set up to do so. This
184 callback has the current yes/no state is in "state". If verification succeeded,
185 we set up the tls_peerdn string. If verification failed, what happens depends
186 on whether the client is required to present a verifiable certificate or not.
188 If verification is optional, we change the state to yes, but still log the
189 verification error. For some reason (it really would help to have proper
190 documentation of OpenSSL), this callback function then gets called again, this
191 time with state = 1. In fact, that's useful, because we can set up the peerdn
192 value, but we must take care not to set the private verified flag on the second
195 Note: this function is not called if the client fails to present a certificate
196 when asked. We get here only if a certificate has been received. Handling of
197 optional verification for this case is done when requesting SSL to verify, by
198 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
201 state current yes/no state as 1/0
202 x509ctx certificate information.
204 Returns: 1 if verified, 0 if not
208 verify_callback(int state
, X509_STORE_CTX
*x509ctx
)
210 static uschar txt
[256];
212 X509_NAME_oneline(X509_get_subject_name(x509ctx
->current_cert
),
213 CS txt
, sizeof(txt
));
217 log_write(0, LOG_MAIN
, "SSL verify error: depth=%d error=%s cert=%s",
218 x509ctx
->error_depth
,
219 X509_verify_cert_error_string(x509ctx
->error
),
221 tls_in
.certificate_verified
= FALSE
;
222 verify_callback_called
= TRUE
;
223 if (!verify_optional
) return 0; /* reject */
224 DEBUG(D_tls
) debug_printf("SSL verify failure overridden (host in "
225 "tls_try_verify_hosts)\n");
226 return 1; /* accept */
229 if (x509ctx
->error_depth
!= 0)
231 DEBUG(D_tls
) debug_printf("SSL verify ok: depth=%d cert=%s\n",
232 x509ctx
->error_depth
, txt
);
236 DEBUG(D_tls
) debug_printf("SSL%s peer: %s\n",
237 verify_callback_called
? "" : " authenticated", txt
);
241 if (!verify_callback_called
) tls_in
.certificate_verified
= TRUE
;
242 verify_callback_called
= TRUE
;
244 return 1; /* accept */
249 /*************************************************
250 * Information callback *
251 *************************************************/
253 /* The SSL library functions call this from time to time to indicate what they
254 are doing. We copy the string to the debugging output when TLS debugging has
266 info_callback(SSL
*s
, int where
, int ret
)
270 DEBUG(D_tls
) debug_printf("SSL info: %s\n", SSL_state_string_long(s
));
275 /*************************************************
276 * Initialize for DH *
277 *************************************************/
279 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
282 dhparam DH parameter file or fixed parameter identity string
283 host connected host, if client; NULL if server
285 Returns: TRUE if OK (nothing to set up, or setup worked)
290 init_dh(SSL_CTX
*sctx
, uschar
*dhparam
, host_item
*host
)
292 init_dh(SSL_CTX
*ctx
, uschar
*dhparam
, host_item
*host
)
293 >>>>>>> Dual
-tls
- split management of TLS into in
- and out
-bound connection
-handling
.
300 if (!expand_check(dhparam
, US
"tls_dhparam", &dhexpanded
))
303 if (dhexpanded
== NULL
|| *dhexpanded
== '\0')
305 bio
= BIO_new_mem_buf(CS
std_dh_prime_default(), -1);
307 else if (dhexpanded
[0] == '/')
309 bio
= BIO_new_file(CS dhexpanded
, "r");
312 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded
),
313 host
, US
strerror(errno
));
319 if (Ustrcmp(dhexpanded
, "none") == 0)
321 DEBUG(D_tls
) debug_printf("Requested no DH parameters.\n");
325 pem
= std_dh_prime_named(dhexpanded
);
328 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded
),
329 host
, US
strerror(errno
));
332 bio
= BIO_new_mem_buf(CS pem
, -1);
335 dh
= PEM_read_bio_DHparams(bio
, NULL
, NULL
, NULL
);
339 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded
),
344 /* Even if it is larger, we silently return success rather than cause things
345 * to fail out, so that a too-large DH will not knock out all TLS; it's a
346 * debatable choice. */
347 if ((8*DH_size(dh
)) > tls_dh_max_bits
)
350 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
351 8*DH_size(dh
), tls_dh_max_bits
);
355 SSL_CTX_set_tmp_dh(sctx
, dh
);
357 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
358 dhexpanded
? dhexpanded
: US
"default", 8*DH_size(dh
));
370 #ifdef EXPERIMENTAL_OCSP
371 /*************************************************
372 * Load OCSP information into state *
373 *************************************************/
375 /* Called to load the OCSP response from the given file into memory, once
376 caller has determined this is needed. Checks validity. Debugs a message
379 ASSUMES: single response, for single cert.
382 sctx the SSL_CTX* to update
383 cbinfo various parts of session state
384 expanded the filename putatively holding an OCSP response
389 ocsp_load_response(SSL_CTX
*sctx
,
390 tls_ext_ctx_cb
*cbinfo
,
391 const uschar
*expanded
)
395 OCSP_BASICRESP
*basic_response
;
396 OCSP_SINGLERESP
*single_response
;
397 ASN1_GENERALIZEDTIME
*rev
, *thisupd
, *nextupd
;
399 unsigned long verify_flags
;
400 int status
, reason
, i
;
402 cbinfo
->ocsp_file_expanded
= string_copy(expanded
);
403 if (cbinfo
->ocsp_response
)
405 OCSP_RESPONSE_free(cbinfo
->ocsp_response
);
406 cbinfo
->ocsp_response
= NULL
;
409 bio
= BIO_new_file(CS cbinfo
->ocsp_file_expanded
, "rb");
412 DEBUG(D_tls
) debug_printf("Failed to open OCSP response file \"%s\"\n",
413 cbinfo
->ocsp_file_expanded
);
417 resp
= d2i_OCSP_RESPONSE_bio(bio
, NULL
);
421 DEBUG(D_tls
) debug_printf("Error reading OCSP response.\n");
425 status
= OCSP_response_status(resp
);
426 if (status
!= OCSP_RESPONSE_STATUS_SUCCESSFUL
)
428 DEBUG(D_tls
) debug_printf("OCSP response not valid: %s (%d)\n",
429 OCSP_response_status_str(status
), status
);
433 basic_response
= OCSP_response_get1_basic(resp
);
437 debug_printf("OCSP response parse error: unable to extract basic response.\n");
441 store
= SSL_CTX_get_cert_store(sctx
);
442 verify_flags
= OCSP_NOVERIFY
; /* check sigs, but not purpose */
444 /* May need to expose ability to adjust those flags?
445 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
446 OCSP_TRUSTOTHER OCSP_NOINTERN */
448 i
= OCSP_basic_verify(basic_response
, NULL
, store
, verify_flags
);
452 ERR_error_string(ERR_get_error(), ssl_errstring
);
453 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring
);
458 /* Here's the simplifying assumption: there's only one response, for the
459 one certificate we use, and nothing for anything else in a chain. If this
460 proves false, we need to extract a cert id from our issued cert
461 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
462 right cert in the stack and then calls OCSP_single_get0_status()).
464 I'm hoping to avoid reworking a bunch more of how we handle state here. */
465 single_response
= OCSP_resp_get0(basic_response
, 0);
466 if (!single_response
)
469 debug_printf("Unable to get first response from OCSP basic response.\n");
473 status
= OCSP_single_get0_status(single_response
, &reason
, &rev
, &thisupd
, &nextupd
);
474 /* how does this status differ from the one above? */
475 if (status
!= OCSP_RESPONSE_STATUS_SUCCESSFUL
)
477 DEBUG(D_tls
) debug_printf("OCSP response not valid (take 2): %s (%d)\n",
478 OCSP_response_status_str(status
), status
);
482 if (!OCSP_check_validity(thisupd
, nextupd
, EXIM_OCSP_SKEW_SECONDS
, EXIM_OCSP_MAX_AGE
))
484 DEBUG(D_tls
) debug_printf("OCSP status invalid times.\n");
488 cbinfo
->ocsp_response
= resp
;
495 /*************************************************
496 * Expand key and cert file specs *
497 *************************************************/
499 /* Called once during tls_init and possibly againt during TLS setup, for a
500 new context, if Server Name Indication was used and tls_sni was seen in
501 the certificate string.
504 sctx the SSL_CTX* to update
505 cbinfo various parts of session state
507 Returns: OK/DEFER/FAIL
511 tls_expand_session_files(SSL_CTX
*sctx
, tls_ext_ctx_cb
*cbinfo
)
515 if (cbinfo
->certificate
== NULL
)
518 if (Ustrstr(cbinfo
->certificate
, US
"tls_sni"))
519 reexpand_tls_files_for_sni
= TRUE
;
521 if (!expand_check(cbinfo
->certificate
, US
"tls_certificate", &expanded
))
524 if (expanded
!= NULL
)
526 DEBUG(D_tls
) debug_printf("tls_certificate file %s\n", expanded
);
527 if (!SSL_CTX_use_certificate_chain_file(sctx
, CS expanded
))
528 return tls_error(string_sprintf(
529 "SSL_CTX_use_certificate_chain_file file=%s", expanded
),
533 if (cbinfo
->privatekey
!= NULL
&&
534 !expand_check(cbinfo
->privatekey
, US
"tls_privatekey", &expanded
))
537 /* If expansion was forced to fail, key_expanded will be NULL. If the result
538 of the expansion is an empty string, ignore it also, and assume the private
539 key is in the same file as the certificate. */
541 if (expanded
!= NULL
&& *expanded
!= 0)
543 DEBUG(D_tls
) debug_printf("tls_privatekey file %s\n", expanded
);
544 if (!SSL_CTX_use_PrivateKey_file(sctx
, CS expanded
, SSL_FILETYPE_PEM
))
545 return tls_error(string_sprintf(
546 "SSL_CTX_use_PrivateKey_file file=%s", expanded
), cbinfo
->host
, NULL
);
549 #ifdef EXPERIMENTAL_OCSP
550 if (cbinfo
->ocsp_file
!= NULL
)
552 if (!expand_check(cbinfo
->ocsp_file
, US
"tls_ocsp_file", &expanded
))
555 if (expanded
!= NULL
&& *expanded
!= 0)
557 DEBUG(D_tls
) debug_printf("tls_ocsp_file %s\n", expanded
);
558 if (cbinfo
->ocsp_file_expanded
&&
559 (Ustrcmp(expanded
, cbinfo
->ocsp_file_expanded
) == 0))
562 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
564 ocsp_load_response(sctx
, cbinfo
, expanded
);
576 /*************************************************
577 * Callback to handle SNI *
578 *************************************************/
580 /* Called when acting as server during the TLS session setup if a Server Name
581 Indication extension was sent by the client.
583 API documentation is OpenSSL s_server.c implementation.
586 s SSL* of the current session
587 ad unknown (part of OpenSSL API) (unused)
588 arg Callback of "our" registered data
590 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
593 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
595 tls_servername_cb(SSL
*s
, int *ad ARG_UNUSED
, void *arg
)
597 const char *servername
= SSL_get_servername(s
, TLSEXT_NAMETYPE_host_name
);
598 tls_ext_ctx_cb
*cbinfo
= (tls_ext_ctx_cb
*) arg
;
600 int old_pool
= store_pool
;
603 return SSL_TLSEXT_ERR_OK
;
605 DEBUG(D_tls
) debug_printf("Received TLS SNI \"%s\"%s\n", servername
,
606 reexpand_tls_files_for_sni
? "" : " (unused for certificate selection)");
608 /* Make the extension value available for expansion */
609 store_pool
= POOL_PERM
;
610 tls_in
.sni
= string_copy(US servername
);
611 store_pool
= old_pool
;
613 if (!reexpand_tls_files_for_sni
)
614 return SSL_TLSEXT_ERR_OK
;
616 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
617 not confident that memcpy wouldn't break some internal reference counting.
618 Especially since there's a references struct member, which would be off. */
620 server_sni
= SSL_CTX_new(SSLv23_server_method());
623 ERR_error_string(ERR_get_error(), ssl_errstring
);
624 DEBUG(D_tls
) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring
);
625 return SSL_TLSEXT_ERR_NOACK
;
628 /* Not sure how many of these are actually needed, since SSL object
629 already exists. Might even need this selfsame callback, for reneg? */
631 SSL_CTX_set_info_callback(server_sni
, SSL_CTX_get_info_callback(server_ctx
));
632 SSL_CTX_set_mode(server_sni
, SSL_CTX_get_mode(server_ctx
));
633 SSL_CTX_set_options(server_sni
, SSL_CTX_get_options(server_ctx
));
634 SSL_CTX_set_timeout(server_sni
, SSL_CTX_get_timeout(server_ctx
));
635 SSL_CTX_set_tlsext_servername_callback(server_sni
, tls_servername_cb
);
636 SSL_CTX_set_tlsext_servername_arg(server_sni
, cbinfo
);
637 if (cbinfo
->server_cipher_list
)
638 SSL_CTX_set_cipher_list(server_sni
, CS cbinfo
->server_cipher_list
);
639 #ifdef EXPERIMENTAL_OCSP
640 if (cbinfo
->ocsp_file
)
642 SSL_CTX_set_tlsext_status_cb(server_sni
, tls_stapling_cb
);
643 SSL_CTX_set_tlsext_status_arg(ctx
, cbinfo
);
647 rc
= setup_certs(server_sni
, tls_verify_certificates
, tls_crl
, NULL
, FALSE
);
648 if (rc
!= OK
) return SSL_TLSEXT_ERR_NOACK
;
650 /* do this after setup_certs, because this can require the certs for verifying
652 rc
= tls_expand_session_files(server_sni
, cbinfo
);
653 if (rc
!= OK
) return SSL_TLSEXT_ERR_NOACK
;
655 rc
= init_dh(ctx_sni
, cbinfo
->dhparam
, NULL
);
656 if (rc
!= OK
) return SSL_TLSEXT_ERR_NOACK
;
658 DEBUG(D_tls
) debug_printf("Switching SSL context.\n");
659 SSL_set_SSL_CTX(s
, server_sni
);
661 return SSL_TLSEXT_ERR_OK
;
663 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
668 #ifdef EXPERIMENTAL_OCSP
669 /*************************************************
670 * Callback to handle OCSP Stapling *
671 *************************************************/
673 /* Called when acting as server during the TLS session setup if the client
674 requests OCSP information with a Certificate Status Request.
676 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
682 tls_stapling_cb(SSL
*s
, void *arg
)
684 const tls_ext_ctx_cb
*cbinfo
= (tls_ext_ctx_cb
*) arg
;
685 uschar
*response_der
;
686 int response_der_len
;
688 DEBUG(D_tls
) debug_printf("Received TLS status request (OCSP stapling); %s response.\n",
689 cbinfo
->ocsp_response
? "have" : "lack");
690 if (!cbinfo
->ocsp_response
)
691 return SSL_TLSEXT_ERR_NOACK
;
694 response_der_len
= i2d_OCSP_RESPONSE(cbinfo
->ocsp_response
, &response_der
);
695 if (response_der_len
<= 0)
696 return SSL_TLSEXT_ERR_NOACK
;
698 SSL_set_tlsext_status_ocsp_resp(ssl
, response_der
, response_der_len
);
699 return SSL_TLSEXT_ERR_OK
;
702 #endif /* EXPERIMENTAL_OCSP */
707 /*************************************************
708 * Initialize for TLS *
709 *************************************************/
711 /* Called from both server and client code, to do preliminary initialization of
715 host connected host, if client; NULL if server
716 dhparam DH parameter file
717 certificate certificate file
718 privatekey private key
719 addr address if client; NULL if server (for some randomness)
721 Returns: OK/DEFER/FAIL
725 tls_init(SSL_CTX
**ctxp
, host_item
*host
, uschar
*dhparam
, uschar
*certificate
,
727 #ifdef EXPERIMENTAL_OCSP
730 address_item
*addr
, tls_ext_ctx_cb
** cbp
)
735 tls_ext_ctx_cb
*cbinfo
;
737 cbinfo
= store_malloc(sizeof(tls_ext_ctx_cb
));
738 cbinfo
->certificate
= certificate
;
739 cbinfo
->privatekey
= privatekey
;
740 #ifdef EXPERIMENTAL_OCSP
741 cbinfo
->ocsp_file
= ocsp_file
;
743 cbinfo
->dhparam
= dhparam
;
746 SSL_load_error_strings(); /* basic set up */
747 OpenSSL_add_ssl_algorithms();
749 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
750 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
751 list of available digests. */
752 EVP_add_digest(EVP_sha256());
756 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
757 negotiation in the different methods; as far as I can tell, the only
758 *_{server,client}_method which allows negotiation is SSLv23, which exists even
759 when OpenSSL is built without SSLv2 support.
760 By disabling with openssl_options, we can let admins re-enable with the
763 *ctxp
= SSL_CTX_new((host
== NULL
)?
764 SSLv23_server_method() : SSLv23_client_method());
766 if (*ctxp
== NULL
) return tls_error(US
"SSL_CTX_new", host
, NULL
);
768 /* It turns out that we need to seed the random number generator this early in
769 order to get the full complement of ciphers to work. It took me roughly a day
770 of work to discover this by experiment.
772 On systems that have /dev/urandom, SSL may automatically seed itself from
773 there. Otherwise, we have to make something up as best we can. Double check
779 gettimeofday(&r
.tv
, NULL
);
782 RAND_seed((uschar
*)(&r
), sizeof(r
));
783 RAND_seed((uschar
*)big_buffer
, big_buffer_size
);
784 if (addr
!= NULL
) RAND_seed((uschar
*)addr
, sizeof(addr
));
787 return tls_error(US
"RAND_status", host
,
788 US
"unable to seed random number generator");
791 /* Set up the information callback, which outputs if debugging is at a suitable
794 SSL_CTX_set_info_callback(*ctxp
, (void (*)())info_callback
);
796 /* Automatically re-try reads/writes after renegotiation. */
797 (void) SSL_CTX_set_mode(*ctxp
, SSL_MODE_AUTO_RETRY
);
799 /* Apply administrator-supplied work-arounds.
800 Historically we applied just one requested option,
801 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
802 moved to an administrator-controlled list of options to specify and
803 grandfathered in the first one as the default value for "openssl_options".
805 No OpenSSL version number checks: the options we accept depend upon the
806 availability of the option value macros from OpenSSL. */
808 okay
= tls_openssl_options_parse(openssl_options
, &init_options
);
810 return tls_error(US
"openssl_options parsing failed", host
, NULL
);
814 DEBUG(D_tls
) debug_printf("setting SSL CTX options: %#lx\n", init_options
);
815 if (!(SSL_CTX_set_options(*ctxp
, init_options
)))
816 return tls_error(string_sprintf(
817 "SSL_CTX_set_option(%#lx)", init_options
), host
, NULL
);
820 DEBUG(D_tls
) debug_printf("no SSL CTX options to set\n");
822 /* Initialize with DH parameters if supplied */
825 if (!init_dh(ctx
, dhparam
, host
)) return DEFER
;
827 if (!init_dh(*ctxp
, dhparam
, host
)) return DEFER
;
828 >>>>>>> Dual
-tls
- split management of TLS into in
- and out
-bound connection
-handling
.
830 /* Set up certificate and key (and perhaps OCSP info) */
832 rc
= tls_expand_session_files(*ctxp
, cbinfo
);
833 if (rc
!= OK
) return rc
;
835 /* If we need to handle SNI, do so */
836 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
839 #ifdef EXPERIMENTAL_OCSP
840 /* We check ocsp_file, not ocsp_response, because we care about if
841 the option exists, not what the current expansion might be, as SNI might
842 change the certificate and OCSP file in use between now and the time the
843 callback is invoked. */
844 if (cbinfo
->ocsp_file
)
846 SSL_CTX_set_tlsext_status_cb(ctx
, tls_stapling_cb
);
847 SSL_CTX_set_tlsext_status_arg(ctx
, cbinfo
);
850 /* We always do this, so that $tls_sni is available even if not used in
852 SSL_CTX_set_tlsext_servername_callback(*ctxp
, tls_servername_cb
);
853 SSL_CTX_set_tlsext_servername_arg(*ctxp
, cbinfo
);
857 /* Set up the RSA callback */
859 SSL_CTX_set_tmp_rsa_callback(*ctxp
, rsa_callback
);
861 /* Finally, set the timeout, and we are done */
863 SSL_CTX_set_timeout(*ctxp
, ssl_session_timeout
);
864 DEBUG(D_tls
) debug_printf("Initialized TLS\n");
874 /*************************************************
875 * Get name of cipher in use *
876 *************************************************/
879 Argument: pointer to an SSL structure for the connection
880 buffer to use for answer
882 pointer to number of bits for cipher
887 construct_cipher_name(SSL
*ssl
, uschar
*cipherbuf
, int bsize
, int *bits
)
889 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
890 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
891 the accessor functions use const in the prototype. */
895 switch (ssl
->session
->ssl_version
)
909 #ifdef TLS1_1_VERSION
915 #ifdef TLS1_2_VERSION
925 c
= (const SSL_CIPHER
*) SSL_get_current_cipher(ssl
);
926 SSL_CIPHER_get_bits(c
, bits
);
928 string_format(cipherbuf
, bsize
, "%s:%s:%u", ver
,
929 SSL_CIPHER_get_name(c
), *bits
);
931 DEBUG(D_tls
) debug_printf("Cipher: %s\n", cipherbuf
);
938 /*************************************************
939 * Set up for verifying certificates *
940 *************************************************/
942 /* Called by both client and server startup
945 sctx SSL_CTX* to initialise
946 certs certs file or NULL
948 host NULL in a server; the remote host in a client
949 optional TRUE if called from a server for a host in tls_try_verify_hosts;
950 otherwise passed as FALSE
952 Returns: OK/DEFER/FAIL
956 setup_certs(SSL_CTX
*sctx
, uschar
*certs
, uschar
*crl
, host_item
*host
, BOOL optional
)
958 uschar
*expcerts
, *expcrl
;
960 if (!expand_check(certs
, US
"tls_verify_certificates", &expcerts
))
963 if (expcerts
!= NULL
)
966 if (!SSL_CTX_set_default_verify_paths(sctx
))
967 return tls_error(US
"SSL_CTX_set_default_verify_paths", host
, NULL
);
969 if (Ustat(expcerts
, &statbuf
) < 0)
971 log_write(0, LOG_MAIN
|LOG_PANIC
,
972 "failed to stat %s for certificates", expcerts
);
978 if ((statbuf
.st_mode
& S_IFMT
) == S_IFDIR
)
979 { file
= NULL
; dir
= expcerts
; }
981 { file
= expcerts
; dir
= NULL
; }
983 /* If a certificate file is empty, the next function fails with an
984 unhelpful error message. If we skip it, we get the correct behaviour (no
985 certificates are recognized, but the error message is still misleading (it
986 says no certificate was supplied.) But this is better. */
988 if ((file
== NULL
|| statbuf
.st_size
> 0) &&
989 !SSL_CTX_load_verify_locations(sctx
, CS file
, CS dir
))
990 return tls_error(US
"SSL_CTX_load_verify_locations", host
, NULL
);
994 SSL_CTX_set_client_CA_list(sctx
, SSL_load_client_CA_file(CS file
));
998 /* Handle a certificate revocation list. */
1000 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1002 /* This bit of code is now the version supplied by Lars Mainka. (I have
1003 * merely reformatted it into the Exim code style.)
1005 * "From here I changed the code to add support for multiple crl's
1006 * in pem format in one file or to support hashed directory entries in
1007 * pem format instead of a file. This method now uses the library function
1008 * X509_STORE_load_locations to add the CRL location to the SSL context.
1009 * OpenSSL will then handle the verify against CA certs and CRLs by
1010 * itself in the verify callback." */
1012 if (!expand_check(crl
, US
"tls_crl", &expcrl
)) return DEFER
;
1013 if (expcrl
!= NULL
&& *expcrl
!= 0)
1015 struct stat statbufcrl
;
1016 if (Ustat(expcrl
, &statbufcrl
) < 0)
1018 log_write(0, LOG_MAIN
|LOG_PANIC
,
1019 "failed to stat %s for certificates revocation lists", expcrl
);
1024 /* is it a file or directory? */
1026 X509_STORE
*cvstore
= SSL_CTX_get_cert_store(sctx
);
1027 if ((statbufcrl
.st_mode
& S_IFMT
) == S_IFDIR
)
1031 DEBUG(D_tls
) debug_printf("SSL CRL value is a directory %s\n", dir
);
1037 DEBUG(D_tls
) debug_printf("SSL CRL value is a file %s\n", file
);
1039 if (X509_STORE_load_locations(cvstore
, CS file
, CS dir
) == 0)
1040 return tls_error(US
"X509_STORE_load_locations", host
, NULL
);
1042 /* setting the flags to check against the complete crl chain */
1044 X509_STORE_set_flags(cvstore
,
1045 X509_V_FLAG_CRL_CHECK
|X509_V_FLAG_CRL_CHECK_ALL
);
1049 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1051 /* If verification is optional, don't fail if no certificate */
1053 SSL_CTX_set_verify(sctx
,
1054 SSL_VERIFY_PEER
| (optional
? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT
),
1063 /*************************************************
1064 * Start a TLS session in a server *
1065 *************************************************/
1067 /* This is called when Exim is running as a server, after having received
1068 the STARTTLS command. It must respond to that command, and then negotiate
1072 require_ciphers allowed ciphers
1074 Returns: OK on success
1075 DEFER for errors before the start of the negotiation
1076 FAIL for errors during the negotation; the server can't
1081 tls_server_start(const uschar
*require_ciphers
)
1085 tls_ext_ctx_cb
*cbinfo
;
1086 static uschar cipherbuf
[256];
1088 /* Check for previous activation */
1090 if (tls_in
.active
>= 0)
1092 tls_error(US
"STARTTLS received after TLS started", NULL
, US
"");
1093 smtp_printf("554 Already in TLS\r\n");
1097 /* Initialize the SSL library. If it fails, it will already have logged
1100 rc
= tls_init(&server_ctx
, NULL
, tls_dhparam
, tls_certificate
, tls_privatekey
,
1101 #ifdef EXPERIMENTAL_OCSP
1104 NULL
, &server_static_cbinfo
);
1105 if (rc
!= OK
) return rc
;
1106 cbinfo
= server_static_cbinfo
;
1108 if (!expand_check(require_ciphers
, US
"tls_require_ciphers", &expciphers
))
1111 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1112 were historically separated by underscores. So that I can use either form in my
1113 tests, and also for general convenience, we turn underscores into hyphens here.
1116 if (expciphers
!= NULL
)
1118 uschar
*s
= expciphers
;
1119 while (*s
!= 0) { if (*s
== '_') *s
= '-'; s
++; }
1120 DEBUG(D_tls
) debug_printf("required ciphers: %s\n", expciphers
);
1121 if (!SSL_CTX_set_cipher_list(server_ctx
, CS expciphers
))
1122 return tls_error(US
"SSL_CTX_set_cipher_list", NULL
, NULL
);
1123 cbinfo
->server_cipher_list
= expciphers
;
1126 /* If this is a host for which certificate verification is mandatory or
1127 optional, set up appropriately. */
1129 tls_in
.certificate_verified
= FALSE
;
1130 verify_callback_called
= FALSE
;
1132 if (verify_check_host(&tls_verify_hosts
) == OK
)
1134 rc
= setup_certs(server_ctx
, tls_verify_certificates
, tls_crl
, NULL
, FALSE
);
1135 if (rc
!= OK
) return rc
;
1136 verify_optional
= FALSE
;
1138 else if (verify_check_host(&tls_try_verify_hosts
) == OK
)
1140 rc
= setup_certs(server_ctx
, tls_verify_certificates
, tls_crl
, NULL
, TRUE
);
1141 if (rc
!= OK
) return rc
;
1142 verify_optional
= TRUE
;
1145 /* Prepare for new connection */
1147 if ((server_ssl
= SSL_new(server_ctx
)) == NULL
) return tls_error(US
"SSL_new", NULL
, NULL
);
1149 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1151 * With the SSL_clear(), we get strange interoperability bugs with
1152 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1153 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1155 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1156 * session shutdown. In this case, we have a brand new object and there's no
1157 * obvious reason to immediately clear it. I'm guessing that this was
1158 * originally added because of incomplete initialisation which the clear fixed,
1159 * in some historic release.
1162 /* Set context and tell client to go ahead, except in the case of TLS startup
1163 on connection, where outputting anything now upsets the clients and tends to
1164 make them disconnect. We need to have an explicit fflush() here, to force out
1165 the response. Other smtp_printf() calls do not need it, because in non-TLS
1166 mode, the fflush() happens when smtp_getc() is called. */
1168 SSL_set_session_id_context(server_ssl
, sid_ctx
, Ustrlen(sid_ctx
));
1169 if (!tls_in
.on_connect
)
1171 smtp_printf("220 TLS go ahead\r\n");
1175 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1176 that the OpenSSL library doesn't. */
1178 SSL_set_wfd(server_ssl
, fileno(smtp_out
));
1179 SSL_set_rfd(server_ssl
, fileno(smtp_in
));
1180 SSL_set_accept_state(server_ssl
);
1182 DEBUG(D_tls
) debug_printf("Calling SSL_accept\n");
1184 sigalrm_seen
= FALSE
;
1185 if (smtp_receive_timeout
> 0) alarm(smtp_receive_timeout
);
1186 rc
= SSL_accept(server_ssl
);
1191 tls_error(US
"SSL_accept", NULL
, sigalrm_seen
? US
"timed out" : NULL
);
1192 if (ERR_get_error() == 0)
1193 log_write(0, LOG_MAIN
,
1194 "TLS client disconnected cleanly (rejected our certificate?)");
1198 DEBUG(D_tls
) debug_printf("SSL_accept was successful\n");
1200 /* TLS has been set up. Adjust the input functions to read via TLS,
1201 and initialize things. */
1203 construct_cipher_name(server_ssl
, cipherbuf
, sizeof(cipherbuf
), &tls_in
.bits
);
1204 tls_in
.cipher
= cipherbuf
;
1209 if (SSL_get_shared_ciphers(server_ssl
, CS buf
, sizeof(buf
)) != NULL
)
1210 debug_printf("Shared ciphers: %s\n", buf
);
1214 /* Only used by the server-side tls (tls_in), including tls_getc.
1215 Client-side (tls_out) reads (seem to?) go via
1216 smtp_read_response()/ip_recv().
1217 Hence no need to duplicate for _in and _out.
1219 ssl_xfer_buffer
= store_malloc(ssl_xfer_buffer_size
);
1220 ssl_xfer_buffer_lwm
= ssl_xfer_buffer_hwm
= 0;
1221 ssl_xfer_eof
= ssl_xfer_error
= 0;
1223 receive_getc
= tls_getc
;
1224 receive_ungetc
= tls_ungetc
;
1225 receive_feof
= tls_feof
;
1226 receive_ferror
= tls_ferror
;
1227 receive_smtp_buffered
= tls_smtp_buffered
;
1229 tls_in
.active
= fileno(smtp_out
);
1237 /*************************************************
1238 * Start a TLS session in a client *
1239 *************************************************/
1241 /* Called from the smtp transport after STARTTLS has been accepted.
1244 fd the fd of the connection
1245 host connected host (for messages)
1246 addr the first address
1247 dhparam DH parameter file
1248 certificate certificate file
1249 privatekey private key file
1250 sni TLS SNI to send to remote host
1251 verify_certs file for certificate verify
1252 crl file containing CRL
1253 require_ciphers list of allowed ciphers
1254 dh_min_bits minimum number of bits acceptable in server's DH prime
1256 timeout startup timeout
1258 Returns: OK on success
1259 FAIL otherwise - note that tls_error() will not give DEFER
1260 because this is not a server
1264 tls_client_start(int fd
, host_item
*host
, address_item
*addr
, uschar
*dhparam
,
1265 uschar
*certificate
, uschar
*privatekey
, uschar
*sni
,
1266 uschar
*verify_certs
, uschar
*crl
,
1267 uschar
*require_ciphers
, int dh_min_bits ARG_UNUSED
, int timeout
)
1269 static uschar txt
[256];
1273 static uschar cipherbuf
[256];
1275 rc
= tls_init(&client_ctx
, host
, dhparam
, certificate
, privatekey
,
1276 #ifdef EXPERIMENTAL_OCSP
1279 addr
, &client_static_cbinfo
);
1280 if (rc
!= OK
) return rc
;
1282 tls_out
.certificate_verified
= FALSE
;
1283 verify_callback_called
= FALSE
;
1285 if (!expand_check(require_ciphers
, US
"tls_require_ciphers", &expciphers
))
1288 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1289 are separated by underscores. So that I can use either form in my tests, and
1290 also for general convenience, we turn underscores into hyphens here. */
1292 if (expciphers
!= NULL
)
1294 uschar
*s
= expciphers
;
1295 while (*s
!= 0) { if (*s
== '_') *s
= '-'; s
++; }
1296 DEBUG(D_tls
) debug_printf("required ciphers: %s\n", expciphers
);
1297 if (!SSL_CTX_set_cipher_list(client_ctx
, CS expciphers
))
1298 return tls_error(US
"SSL_CTX_set_cipher_list", host
, NULL
);
1301 rc
= setup_certs(client_ctx
, verify_certs
, crl
, host
, FALSE
);
1302 if (rc
!= OK
) return rc
;
1304 if ((client_ssl
= SSL_new(client_ctx
)) == NULL
) return tls_error(US
"SSL_new", host
, NULL
);
1305 SSL_set_session_id_context(client_ssl
, sid_ctx
, Ustrlen(sid_ctx
));
1306 SSL_set_fd(client_ssl
, fd
);
1307 SSL_set_connect_state(client_ssl
);
1311 if (!expand_check(sni
, US
"tls_sni", &tls_out
.sni
))
1313 if (!Ustrlen(tls_out
.sni
))
1317 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1318 DEBUG(D_tls
) debug_printf("Setting TLS SNI \"%s\"\n", tls_out
.sni
);
1319 SSL_set_tlsext_host_name(client_ssl
, tls_out
.sni
);
1322 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
1328 /* There doesn't seem to be a built-in timeout on connection. */
1330 DEBUG(D_tls
) debug_printf("Calling SSL_connect\n");
1331 sigalrm_seen
= FALSE
;
1333 rc
= SSL_connect(client_ssl
);
1337 return tls_error(US
"SSL_connect", host
, sigalrm_seen
? US
"timed out" : NULL
);
1339 DEBUG(D_tls
) debug_printf("SSL_connect succeeded\n");
1341 /* Beware anonymous ciphers which lead to server_cert being NULL */
1342 server_cert
= SSL_get_peer_certificate (client_ssl
);
1345 tls_out
.peerdn
= US
X509_NAME_oneline(X509_get_subject_name(server_cert
),
1346 CS txt
, sizeof(txt
));
1347 tls_out
.peerdn
= txt
;
1350 tls_out
.peerdn
= NULL
;
1352 construct_cipher_name(client_ssl
, cipherbuf
, sizeof(cipherbuf
), &tls_out
.bits
);
1353 tls_out
.cipher
= cipherbuf
;
1355 tls_out
.active
= fd
;
1363 /*************************************************
1364 * TLS version of getc *
1365 *************************************************/
1367 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
1368 it refills the buffer via the SSL reading function.
1371 Returns: the next character or EOF
1373 Only used by the server-side TLS.
1379 if (ssl_xfer_buffer_lwm
>= ssl_xfer_buffer_hwm
)
1384 DEBUG(D_tls
) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl
,
1385 ssl_xfer_buffer
, ssl_xfer_buffer_size
);
1387 if (smtp_receive_timeout
> 0) alarm(smtp_receive_timeout
);
1388 inbytes
= SSL_read(server_ssl
, CS ssl_xfer_buffer
, ssl_xfer_buffer_size
);
1389 error
= SSL_get_error(server_ssl
, inbytes
);
1392 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
1393 closed down, not that the socket itself has been closed down. Revert to
1394 non-SSL handling. */
1396 if (error
== SSL_ERROR_ZERO_RETURN
)
1398 DEBUG(D_tls
) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1400 receive_getc
= smtp_getc
;
1401 receive_ungetc
= smtp_ungetc
;
1402 receive_feof
= smtp_feof
;
1403 receive_ferror
= smtp_ferror
;
1404 receive_smtp_buffered
= smtp_buffered
;
1406 SSL_free(server_ssl
);
1410 tls_in
.cipher
= NULL
;
1411 tls_in
.peerdn
= NULL
;
1417 /* Handle genuine errors */
1419 else if (error
== SSL_ERROR_SSL
)
1421 ERR_error_string(ERR_get_error(), ssl_errstring
);
1422 log_write(0, LOG_MAIN
, "TLS error (SSL_read): %s", ssl_errstring
);
1427 else if (error
!= SSL_ERROR_NONE
)
1429 DEBUG(D_tls
) debug_printf("Got SSL error %d\n", error
);
1434 #ifndef DISABLE_DKIM
1435 dkim_exim_verify_feed(ssl_xfer_buffer
, inbytes
);
1437 ssl_xfer_buffer_hwm
= inbytes
;
1438 ssl_xfer_buffer_lwm
= 0;
1441 /* Something in the buffer; return next uschar */
1443 return ssl_xfer_buffer
[ssl_xfer_buffer_lwm
++];
1448 /*************************************************
1449 * Read bytes from TLS channel *
1450 *************************************************/
1457 Returns: the number of bytes read
1458 -1 after a failed read
1460 Only used by the client-side TLS.
1464 tls_read(uschar
*buff
, size_t len
)
1469 DEBUG(D_tls
) debug_printf("Calling SSL_read(%p, %p, %u)\n", client_ssl
,
1470 buff
, (unsigned int)len
);
1472 inbytes
= SSL_read(client_ssl
, CS buff
, len
);
1473 error
= SSL_get_error(client_ssl
, inbytes
);
1475 if (error
== SSL_ERROR_ZERO_RETURN
)
1477 DEBUG(D_tls
) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1480 else if (error
!= SSL_ERROR_NONE
)
1492 /*************************************************
1493 * Write bytes down TLS channel *
1494 *************************************************/
1498 is_server channel specifier
1502 Returns: the number of bytes after a successful write,
1503 -1 after a failed write
1505 Used by both server-side and client-side TLS.
1509 tls_write(BOOL is_server
, const uschar
*buff
, size_t len
)
1514 SSL
*ssl
= is_server
? server_ssl
: client_ssl
;
1516 DEBUG(D_tls
) debug_printf("tls_do_write(%p, %d)\n", buff
, left
);
1519 DEBUG(D_tls
) debug_printf("SSL_write(SSL, %p, %d)\n", buff
, left
);
1520 outbytes
= SSL_write(ssl
, CS buff
, left
);
1521 error
= SSL_get_error(ssl
, outbytes
);
1522 DEBUG(D_tls
) debug_printf("outbytes=%d error=%d\n", outbytes
, error
);
1526 ERR_error_string(ERR_get_error(), ssl_errstring
);
1527 log_write(0, LOG_MAIN
, "TLS error (SSL_write): %s", ssl_errstring
);
1530 case SSL_ERROR_NONE
:
1535 case SSL_ERROR_ZERO_RETURN
:
1536 log_write(0, LOG_MAIN
, "SSL channel closed on write");
1539 case SSL_ERROR_SYSCALL
:
1540 log_write(0, LOG_MAIN
, "SSL_write: (from %s) syscall: %s",
1541 sender_fullhost
? sender_fullhost
: US
"<unknown>",
1545 log_write(0, LOG_MAIN
, "SSL_write error %d", error
);
1554 /*************************************************
1555 * Close down a TLS session *
1556 *************************************************/
1558 /* This is also called from within a delivery subprocess forked from the
1559 daemon, to shut down the TLS library, without actually doing a shutdown (which
1560 would tamper with the SSL session in the parent process).
1562 Arguments: TRUE if SSL_shutdown is to be called
1565 Used by both server-side and client-side TLS.
1569 tls_close(BOOL is_server
, BOOL shutdown
)
1571 SSL
**sslp
= is_server
? &server_ssl
: &client_ssl
;
1573 if (*fdp
< 0) return; /* TLS was not active */
1577 DEBUG(D_tls
) debug_printf("tls_close(): shutting down SSL\n");
1578 SSL_shutdown(*sslp
);
1590 /*************************************************
1591 * Let tls_require_ciphers be checked at startup *
1592 *************************************************/
1594 /* The tls_require_ciphers option, if set, must be something which the
1597 Returns: NULL on success, or error message
1601 tls_validate_require_cipher(void)
1604 uschar
*s
, *expciphers
, *err
;
1606 /* this duplicates from tls_init(), we need a better "init just global
1607 state, for no specific purpose" singleton function of our own */
1609 SSL_load_error_strings();
1610 OpenSSL_add_ssl_algorithms();
1611 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1612 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1613 list of available digests. */
1614 EVP_add_digest(EVP_sha256());
1617 if (!(tls_require_ciphers
&& *tls_require_ciphers
))
1620 if (!expand_check(tls_require_ciphers
, US
"tls_require_ciphers", &expciphers
))
1621 return US
"failed to expand tls_require_ciphers";
1623 if (!(expciphers
&& *expciphers
))
1626 /* normalisation ripped from above */
1628 while (*s
!= 0) { if (*s
== '_') *s
= '-'; s
++; }
1632 ctx
= SSL_CTX_new(SSLv23_server_method());
1635 ERR_error_string(ERR_get_error(), ssl_errstring
);
1636 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring
);
1640 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers
);
1642 if (!SSL_CTX_set_cipher_list(ctx
, CS expciphers
))
1644 ERR_error_string(ERR_get_error(), ssl_errstring
);
1645 err
= string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers
);
1656 /*************************************************
1657 * Report the library versions. *
1658 *************************************************/
1660 /* There have historically been some issues with binary compatibility in
1661 OpenSSL libraries; if Exim (like many other applications) is built against
1662 one version of OpenSSL but the run-time linker picks up another version,
1663 it can result in serious failures, including crashing with a SIGSEGV. So
1664 report the version found by the compiler and the run-time version.
1666 Arguments: a FILE* to print the results to
1671 tls_version_report(FILE *f
)
1673 fprintf(f
, "Library version: OpenSSL: Compile: %s\n"
1675 OPENSSL_VERSION_TEXT
,
1676 SSLeay_version(SSLEAY_VERSION
));
1682 /*************************************************
1683 * Random number generation *
1684 *************************************************/
1686 /* Pseudo-random number generation. The result is not expected to be
1687 cryptographically strong but not so weak that someone will shoot themselves
1688 in the foot using it as a nonce in input in some email header scheme or
1689 whatever weirdness they'll twist this into. The result should handle fork()
1690 and avoid repeating sequences. OpenSSL handles that for us.
1694 Returns a random number in range [0, max-1]
1698 vaguely_random_number(int max
)
1703 uschar smallbuf
[sizeof(r
)];
1708 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
1712 gettimeofday(&r
.tv
, NULL
);
1715 RAND_seed((uschar
*)(&r
), sizeof(r
));
1717 /* We're after pseudo-random, not random; if we still don't have enough data
1718 in the internal PRNG then our options are limited. We could sleep and hope
1719 for entropy to come along (prayer technique) but if the system is so depleted
1720 in the first place then something is likely to just keep taking it. Instead,
1721 we'll just take whatever little bit of pseudo-random we can still manage to
1724 needed_len
= sizeof(r
);
1725 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
1726 asked for a number less than 10. */
1727 for (r
= max
, i
= 0; r
; ++i
)
1733 /* We do not care if crypto-strong */
1734 i
= RAND_pseudo_bytes(smallbuf
, needed_len
);
1738 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
1739 return vaguely_random_number_fallback(max
);
1743 for (p
= smallbuf
; needed_len
; --needed_len
, ++p
)
1749 /* We don't particularly care about weighted results; if someone wants
1750 smooth distribution and cares enough then they should submit a patch then. */
1757 /*************************************************
1758 * OpenSSL option parse *
1759 *************************************************/
1761 /* Parse one option for tls_openssl_options_parse below
1764 name one option name
1765 value place to store a value for it
1766 Returns success or failure in parsing
1769 struct exim_openssl_option
{
1773 /* We could use a macro to expand, but we need the ifdef and not all the
1774 options document which version they were introduced in. Policylet: include
1775 all options unless explicitly for DTLS, let the administrator choose which
1778 This list is current as of:
1780 static struct exim_openssl_option exim_openssl_options
[] = {
1781 /* KEEP SORTED ALPHABETICALLY! */
1783 { US
"all", SSL_OP_ALL
},
1785 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
1786 { US
"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
},
1788 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
1789 { US
"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE
},
1791 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
1792 { US
"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
},
1794 #ifdef SSL_OP_EPHEMERAL_RSA
1795 { US
"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA
},
1797 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
1798 { US
"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT
},
1800 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
1801 { US
"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
},
1803 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
1804 { US
"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG
},
1806 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
1807 { US
"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING
},
1809 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
1810 { US
"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG
},
1812 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
1813 { US
"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
},
1815 #ifdef SSL_OP_NO_COMPRESSION
1816 { US
"no_compression", SSL_OP_NO_COMPRESSION
},
1818 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
1819 { US
"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
},
1821 #ifdef SSL_OP_NO_SSLv2
1822 { US
"no_sslv2", SSL_OP_NO_SSLv2
},
1824 #ifdef SSL_OP_NO_SSLv3
1825 { US
"no_sslv3", SSL_OP_NO_SSLv3
},
1827 #ifdef SSL_OP_NO_TICKET
1828 { US
"no_ticket", SSL_OP_NO_TICKET
},
1830 #ifdef SSL_OP_NO_TLSv1
1831 { US
"no_tlsv1", SSL_OP_NO_TLSv1
},
1833 #ifdef SSL_OP_NO_TLSv1_1
1834 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
1835 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
1836 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
1838 { US
"no_tlsv1_1", SSL_OP_NO_TLSv1_1
},
1841 #ifdef SSL_OP_NO_TLSv1_2
1842 { US
"no_tlsv1_2", SSL_OP_NO_TLSv1_2
},
1844 #ifdef SSL_OP_SINGLE_DH_USE
1845 { US
"single_dh_use", SSL_OP_SINGLE_DH_USE
},
1847 #ifdef SSL_OP_SINGLE_ECDH_USE
1848 { US
"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE
},
1850 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
1851 { US
"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG
},
1853 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
1854 { US
"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
},
1856 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
1857 { US
"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG
},
1859 #ifdef SSL_OP_TLS_D5_BUG
1860 { US
"tls_d5_bug", SSL_OP_TLS_D5_BUG
},
1862 #ifdef SSL_OP_TLS_ROLLBACK_BUG
1863 { US
"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG
},
1866 static int exim_openssl_options_size
=
1867 sizeof(exim_openssl_options
)/sizeof(struct exim_openssl_option
);
1871 tls_openssl_one_option_parse(uschar
*name
, long *value
)
1874 int last
= exim_openssl_options_size
;
1875 while (last
> first
)
1877 int middle
= (first
+ last
)/2;
1878 int c
= Ustrcmp(name
, exim_openssl_options
[middle
].name
);
1881 *value
= exim_openssl_options
[middle
].value
;
1895 /*************************************************
1896 * OpenSSL option parsing logic *
1897 *************************************************/
1899 /* OpenSSL has a number of compatibility options which an administrator might
1900 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
1901 we look like log_selector.
1904 option_spec the administrator-supplied string of options
1905 results ptr to long storage for the options bitmap
1906 Returns success or failure
1910 tls_openssl_options_parse(uschar
*option_spec
, long *results
)
1915 BOOL adding
, item_parsed
;
1918 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
1919 * from default because it increases BEAST susceptibility. */
1920 #ifdef SSL_OP_NO_SSLv2
1921 result
|= SSL_OP_NO_SSLv2
;
1924 if (option_spec
== NULL
)
1930 for (s
=option_spec
; *s
!= '\0'; /**/)
1932 while (isspace(*s
)) ++s
;
1935 if (*s
!= '+' && *s
!= '-')
1937 DEBUG(D_tls
) debug_printf("malformed openssl option setting: "
1938 "+ or - expected but found \"%s\"\n", s
);
1941 adding
= *s
++ == '+';
1942 for (end
= s
; (*end
!= '\0') && !isspace(*end
); ++end
) /**/ ;
1945 item_parsed
= tls_openssl_one_option_parse(s
, &item
);
1948 DEBUG(D_tls
) debug_printf("openssl option setting unrecognised: \"%s\"\n", s
);
1951 DEBUG(D_tls
) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
1952 adding
? "adding" : "removing", result
, item
, s
);
1965 /* End of tls-openssl.c */