1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2019 */
6 /* Copyright (c) The Exim Maintainers 2020 - 2021 */
7 /* See the file NOTICE for conditions of use and distribution. */
9 /* Portions Copyright (c) The OpenSSL Project 1999 */
11 /* This module provides the TLS (aka SSL) support for Exim using the OpenSSL
12 library. It is #included into the tls.c file when that library is used. The
13 code herein is based on a patch that was originally contributed by Steve
14 Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara.
16 No cryptographic code is included in Exim. All this module does is to call
17 functions from the OpenSSL library. */
22 #include <openssl/lhash.h>
23 #include <openssl/ssl.h>
24 #include <openssl/err.h>
25 #include <openssl/rand.h>
26 #ifndef OPENSSL_NO_ECDH
27 # include <openssl/ec.h>
30 # include <openssl/ocsp.h>
38 # define EXIM_OCSP_SKEW_SECONDS (300L)
39 # define EXIM_OCSP_MAX_AGE (-1L)
42 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
43 # define EXIM_HAVE_OPENSSL_TLSEXT
45 #if OPENSSL_VERSION_NUMBER >= 0x00908000L
46 # define EXIM_HAVE_RSA_GENKEY_EX
48 #if OPENSSL_VERSION_NUMBER >= 0x10100000L
49 # define EXIM_HAVE_OCSP_RESP_COUNT
50 # define OPENSSL_AUTO_SHA256
52 # define EXIM_HAVE_EPHEM_RSA_KEX
53 # define EXIM_HAVE_RAND_PSEUDO
55 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
56 # define EXIM_HAVE_SHA256
59 /* X509_check_host provides sane certificate hostname checking, but was added
60 to OpenSSL late, after other projects forked off the code-base. So in
61 addition to guarding against the base version number, beware that LibreSSL
62 does not (at this time) support this function.
64 If LibreSSL gains a different API, perhaps via libtls, then we'll probably
65 opt to disentangle and ask a LibreSSL user to provide glue for a third
66 crypto provider for libtls instead of continuing to tie the OpenSSL glue
67 into even twistier knots. If LibreSSL gains the same API, we can just
68 change this guard and punt the issue for a while longer. */
70 #ifndef LIBRESSL_VERSION_NUMBER
71 # if OPENSSL_VERSION_NUMBER >= 0x010100000L
72 # define EXIM_HAVE_OPENSSL_CHECKHOST
73 # define EXIM_HAVE_OPENSSL_DH_BITS
74 # define EXIM_HAVE_OPENSSL_TLS_METHOD
75 # define EXIM_HAVE_OPENSSL_KEYLOG
76 # define EXIM_HAVE_OPENSSL_CIPHER_GET_ID
77 # define EXIM_HAVE_SESSION_TICKET
78 # define EXIM_HAVE_OPESSL_TRACE
79 # define EXIM_HAVE_OPESSL_GET0_SERIAL
81 # define EXIM_HAVE_OCSP
83 # define EXIM_HAVE_ALPN /* fail ret from hshake-cb is ignored by LibreSSL */
85 # define EXIM_NEED_OPENSSL_INIT
87 # if OPENSSL_VERSION_NUMBER >= 0x010000000L \
88 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
89 # define EXIM_HAVE_OPENSSL_CHECKHOST
93 #if LIBRESSL_VERSION_NUMBER >= 0x3040000fL
94 # define EXIM_HAVE_OPENSSL_CIPHER_GET_ID
97 #if !defined(LIBRESSL_VERSION_NUMBER) \
98 || LIBRESSL_VERSION_NUMBER >= 0x20010000L
99 # if !defined(OPENSSL_NO_ECDH)
100 # if OPENSSL_VERSION_NUMBER >= 0x0090800fL
101 # define EXIM_HAVE_ECDH
103 # if OPENSSL_VERSION_NUMBER >= 0x10002000L
104 # define EXIM_HAVE_OPENSSL_EC_NIST2NID
109 #ifndef LIBRESSL_VERSION_NUMBER
110 # if OPENSSL_VERSION_NUMBER >= 0x010101000L
111 # define OPENSSL_HAVE_KEYLOG_CB
112 # define OPENSSL_HAVE_NUM_TICKETS
113 # define EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
115 # define OPENSSL_BAD_SRVR_OURCERT
119 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
120 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
121 # define DISABLE_OCSP
124 #ifndef DISABLE_TLS_RESUME
125 # if OPENSSL_VERSION_NUMBER < 0x0101010L
126 # error OpenSSL version too old for session-resumption
130 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
131 # include <openssl/x509v3.h>
134 #ifndef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
135 # ifndef EXIM_HAVE_OPENSSL_CIPHER_GET_ID
136 # define SSL_CIPHER_get_id(c) (c->id)
138 # ifndef MACRO_PREDEF
139 # include "tls-cipher-stdname.c"
143 /*************************************************
144 * OpenSSL option parse *
145 *************************************************/
147 typedef struct exim_openssl_option {
150 } exim_openssl_option;
151 /* We could use a macro to expand, but we need the ifdef and not all the
152 options document which version they were introduced in. Policylet: include
153 all options unless explicitly for DTLS, let the administrator choose which
156 This list is current as of:
159 XXX could we autobuild this list, as with predefined-macros?
160 Seems just parsing ssl.h for SSL_OP_.* would be enough (except to exclude DTLS).
161 Also allow a numeric literal?
163 static exim_openssl_option exim_openssl_options[] = {
164 /* KEEP SORTED ALPHABETICALLY! */
166 { US"all", (long) SSL_OP_ALL },
168 #ifdef SSL_OP_ALLOW_NO_DHE_KEX
169 { US"allow_no_dhe_kex", SSL_OP_ALLOW_NO_DHE_KEX },
171 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
172 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
174 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
175 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
177 #ifdef SSL_OP_CRYPTOPRO_TLSEXT_BUG
178 { US"cryptopro_tlsext_bug", SSL_OP_CRYPTOPRO_TLSEXT_BUG },
180 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
181 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
183 #ifdef SSL_OP_ENABLE_MIDDLEBOX_COMPAT
184 { US"enable_middlebox_compat", SSL_OP_ENABLE_MIDDLEBOX_COMPAT },
186 #ifdef SSL_OP_EPHEMERAL_RSA
187 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
189 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
190 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
192 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
193 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
195 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
196 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
198 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
199 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
201 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
202 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
204 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
205 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
207 #ifdef SSL_OP_NO_ANTI_REPLAY
208 { US"no_anti_replay", SSL_OP_NO_ANTI_REPLAY },
210 #ifdef SSL_OP_NO_COMPRESSION
211 { US"no_compression", SSL_OP_NO_COMPRESSION },
213 #ifdef SSL_OP_NO_ENCRYPT_THEN_MAC
214 { US"no_encrypt_then_mac", SSL_OP_NO_ENCRYPT_THEN_MAC },
216 #ifdef SSL_OP_NO_RENEGOTIATION
217 { US"no_renegotiation", SSL_OP_NO_RENEGOTIATION },
219 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
220 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
222 #ifdef SSL_OP_NO_SSLv2
223 { US"no_sslv2", SSL_OP_NO_SSLv2 },
225 #ifdef SSL_OP_NO_SSLv3
226 { US"no_sslv3", SSL_OP_NO_SSLv3 },
228 #ifdef SSL_OP_NO_TICKET
229 { US"no_ticket", SSL_OP_NO_TICKET },
231 #ifdef SSL_OP_NO_TLSv1
232 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
234 #ifdef SSL_OP_NO_TLSv1_1
235 # if OPENSSL_VERSION_NUMBER < 0x30000000L
236 # if SSL_OP_NO_TLSv1_1 == 0x00000400L
237 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
238 # warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
239 # define NO_SSL_OP_NO_TLSv1_1
242 # ifndef NO_SSL_OP_NO_TLSv1_1
243 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
246 #ifdef SSL_OP_NO_TLSv1_2
247 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
249 #ifdef SSL_OP_NO_TLSv1_3
250 { US"no_tlsv1_3", SSL_OP_NO_TLSv1_3 },
252 #ifdef SSL_OP_PRIORITIZE_CHACHA
253 { US"prioritize_chacha", SSL_OP_PRIORITIZE_CHACHA },
255 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
256 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
258 #ifdef SSL_OP_SINGLE_DH_USE
259 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
261 #ifdef SSL_OP_SINGLE_ECDH_USE
262 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
264 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
265 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
267 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
268 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
270 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
271 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
273 #ifdef SSL_OP_TLS_D5_BUG
274 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
276 #ifdef SSL_OP_TLS_ROLLBACK_BUG
277 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
279 #ifdef SSL_OP_TLSEXT_PADDING
280 { US"tlsext_padding", SSL_OP_TLSEXT_PADDING },
285 static int exim_openssl_options_size = nelem(exim_openssl_options);
286 static long init_options = 0;
295 for (struct exim_openssl_option * o = exim_openssl_options;
296 o < exim_openssl_options + nelem(exim_openssl_options); o++)
298 /* Trailing X is workaround for problem with _OPT_OPENSSL_NO_TLSV1
299 being a ".ifdef _OPT_OPENSSL_NO_TLSV1_3" match */
301 spf(buf, sizeof(buf), US"_OPT_OPENSSL_%T_X", o->name);
302 builtin_macro_create(buf);
305 # ifndef DISABLE_TLS_RESUME
306 builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING );
308 # ifdef SSL_OP_NO_TLSv1_3
309 builtin_macro_create(US"_HAVE_TLS1_3");
311 # ifdef OPENSSL_BAD_SRVR_OURCERT
312 builtin_macro_create(US"_TLS_BAD_MULTICERT_IN_OURCERT");
314 # ifdef EXIM_HAVE_OCSP
315 builtin_macro_create(US"_HAVE_TLS_OCSP");
316 builtin_macro_create(US"_HAVE_TLS_OCSP_LIST");
318 # ifdef EXIM_HAVE_ALPN
319 builtin_macro_create(US"_HAVE_TLS_ALPN");
324 /******************************************************************************/
326 /* Structure for collecting random data for seeding. */
328 typedef struct randstuff {
333 /* Local static variables */
335 static BOOL client_verify_callback_called = FALSE;
336 static BOOL server_verify_callback_called = FALSE;
337 static const uschar *sid_ctx = US"exim";
339 /* We have three different contexts to care about.
341 Simple case: client, `client_ctx`
342 As a client, we can be doing a callout or cut-through delivery while receiving
343 a message. So we have a client context, which should have options initialised
344 from the SMTP Transport. We may also concurrently want to make TLS connections
345 to utility daemons, so client-contexts are allocated and passed around in call
346 args rather than using a gobal.
349 There are two cases: with and without ServerNameIndication from the client.
350 Given TLS SNI, we can be using different keys, certs and various other
351 configuration settings, because they're re-expanded with $tls_sni set. This
352 allows vhosting with TLS. This SNI is sent in the handshake.
353 A client might not send SNI, so we need a fallback, and an initial setup too.
354 So as a server, we start out using `server_ctx`.
355 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
356 `server_sni` from `server_ctx` and then initialise settings by re-expanding
364 } exim_openssl_client_tls_ctx;
367 /* static SSL_CTX *server_ctx = NULL; */
368 /* static SSL *server_ssl = NULL; */
370 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
371 static SSL_CTX *server_sni = NULL;
373 #ifdef EXIM_HAVE_ALPN
374 static BOOL server_seen_alpn = FALSE;
377 static char ssl_errstring[256];
379 static int ssl_session_timeout = 7200; /* Two hours */
380 static BOOL client_verify_optional = FALSE;
381 static BOOL server_verify_optional = FALSE;
383 static BOOL reexpand_tls_files_for_sni = FALSE;
386 typedef struct ocsp_resp {
387 struct ocsp_resp * next;
388 OCSP_RESPONSE * resp;
391 typedef struct exim_openssl_state {
392 exim_tlslib_state lib_state;
393 #define lib_ctx libdata0
394 #define lib_ssl libdata1
397 uschar * certificate;
401 STACK_OF(X509) *verify_stack; /* chain for verifying the proof */
405 const uschar *file_expanded;
406 ocsp_resplist *olist;
409 X509_STORE *verify_store; /* non-null if status requested */
410 BOOL verify_required;
415 /* these are cached from first expand */
416 uschar * server_cipher_list;
417 /* only passed down to tls_error: */
419 const uschar * verify_cert_hostnames;
420 #ifndef DISABLE_EVENT
421 uschar * event_action;
423 } exim_openssl_state_st;
425 /* should figure out a cleanup of API to handle state preserved per
426 implementation, for various reasons, which can be void * in the APIs.
427 For now, we hack around it. */
428 exim_openssl_state_st *client_static_state = NULL; /*XXX should not use static; multiple concurrent clients! */
429 exim_openssl_state_st state_server = {.is_server = TRUE};
432 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host,
437 static int tls_server_stapling_cb(SSL *s, void *arg);
442 /* Daemon-called, before every connection, key create/rotate */
443 #ifndef DISABLE_TLS_RESUME
444 static void tk_init(void);
445 static int tls_exdata_idx = -1;
449 tls_per_lib_daemon_tick(void)
451 #ifndef DISABLE_TLS_RESUME
456 /* Called once at daemon startup */
459 tls_per_lib_daemon_init(void)
461 tls_daemon_creds_reload();
465 /*************************************************
467 *************************************************/
469 /* Called from lots of places when errors occur before actually starting to do
470 the TLS handshake, that is, while the session is still in clear. Always returns
471 DEFER for a server and FAIL for a client so that most calls can use "return
472 tls_error(...)" to do this processing and then give an appropriate return. A
473 single function is used for both server and client, because it is called from
474 some shared functions.
477 prefix text to include in the logged error
478 host NULL if setting up a server;
479 the connected host if setting up a client
480 msg error message or NULL if we should ask OpenSSL
481 errstr pointer to output error message
483 Returns: OK/DEFER/FAIL
487 tls_error(uschar * prefix, const host_item * host, uschar * msg, uschar ** errstr)
491 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
492 msg = US ssl_errstring;
495 msg = string_sprintf("(%s): %s", prefix, msg);
496 DEBUG(D_tls) debug_printf("TLS error '%s'\n", msg);
497 if (errstr) *errstr = msg;
498 return host ? FAIL : DEFER;
503 /**************************************************
504 * General library initalisation *
505 **************************************************/
508 lib_rand_init(void * addr)
511 if (!RAND_status()) return TRUE;
513 gettimeofday(&r.tv, NULL);
515 RAND_seed(US (&r), sizeof(r));
516 RAND_seed(US big_buffer, big_buffer_size);
517 if (addr) RAND_seed(US addr, sizeof(addr));
519 return RAND_status();
524 tls_openssl_init(void)
526 static BOOL once = FALSE;
530 #ifdef EXIM_NEED_OPENSSL_INIT
531 SSL_load_error_strings(); /* basic set up */
532 OpenSSL_add_ssl_algorithms();
535 #if defined(EXIM_HAVE_SHA256) && !defined(OPENSSL_AUTO_SHA256)
536 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
537 list of available digests. */
538 EVP_add_digest(EVP_sha256());
541 (void) lib_rand_init(NULL);
542 (void) tls_openssl_options_parse(openssl_options, &init_options);
547 /*************************************************
548 * Initialize for DH *
549 *************************************************/
551 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
554 sctx The current SSL CTX (inbound or outbound)
555 dhparam DH parameter file or fixed parameter identity string
556 host connected host, if client; NULL if server
557 errstr error string pointer
559 Returns: TRUE if OK (nothing to set up, or setup worked)
563 init_dh(SSL_CTX * sctx, uschar * dhparam, const host_item * host, uschar ** errstr)
566 #if OPENSSL_VERSION_NUMBER < 0x30000000L
575 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded, errstr))
578 if (!dhexpanded || !*dhexpanded)
579 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
580 else if (dhexpanded[0] == '/')
582 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
584 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
585 host, US strerror(errno), errstr);
591 if (Ustrcmp(dhexpanded, "none") == 0)
593 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
597 if (!(pem = std_dh_prime_named(dhexpanded)))
599 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
600 host, US strerror(errno), errstr);
603 bio = BIO_new_mem_buf(CS pem, -1);
607 #if OPENSSL_VERSION_NUMBER < 0x30000000L
608 dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)
610 pkey = PEM_read_bio_Parameters_ex(bio, NULL, NULL, NULL)
615 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
620 /* note: our default limit of 2236 is not a multiple of 8; the limit comes from
621 an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with 2236.
622 But older OpenSSL can only report in bytes (octets), not bits. If someone wants
623 to dance at the edge, then they can raise the limit or use current libraries. */
625 #if OPENSSL_VERSION_NUMBER < 0x30000000L
626 # ifdef EXIM_HAVE_OPENSSL_DH_BITS
627 /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022
628 This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */
629 dh_bitsize = DH_bits(dh);
631 dh_bitsize = 8 * DH_size(dh);
634 dh_bitsize = EVP_PKEY_get_bits(pkey);
637 /* Even if it is larger, we silently return success rather than cause things to
638 fail out, so that a too-large DH will not knock out all TLS; it's a debatable
641 if (dh_bitsize <= tls_dh_max_bits)
644 #if OPENSSL_VERSION_NUMBER < 0x30000000L
645 SSL_CTX_set_tmp_dh(sctx, dh)
647 SSL_CTX_set0_tmp_dh_pkey(sctx, pkey)
651 DEBUG(D_tls) debug_printf("failed to set D-H parameters\n");
652 #if OPENSSL_VERSION_NUMBER < 0x30000000L
660 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
661 dhexpanded ? dhexpanded : US"default", dh_bitsize);
665 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d\n",
666 dh_bitsize, tls_dh_max_bits);
668 #if OPENSSL_VERSION_NUMBER < 0x30000000L
679 /*************************************************
680 * Initialize for ECDH *
681 *************************************************/
683 /* Load parameters for ECDH encryption.
685 For now, we stick to NIST P-256 because: it's simple and easy to configure;
686 it avoids any patent issues that might bite redistributors; despite events in
687 the news and concerns over curve choices, we're not cryptographers, we're not
688 pretending to be, and this is "good enough" to be better than no support,
689 protecting against most adversaries. Given another year or two, there might
690 be sufficient clarity about a "right" way forward to let us make an informed
691 decision, instead of a knee-jerk reaction.
693 Longer-term, we should look at supporting both various named curves and
694 external files generated with "openssl ecparam", much as we do for init_dh().
695 We should also support "none" as a value, to explicitly avoid initialisation.
700 sctx The current SSL CTX (inbound or outbound)
701 host connected host, if client; NULL if server
702 errstr error string pointer
704 Returns: TRUE if OK (nothing to set up, or setup worked)
708 init_ecdh(SSL_CTX * sctx, host_item * host, uschar ** errstr)
710 #ifdef OPENSSL_NO_ECDH
718 if (host) /* No ECDH setup for clients, only for servers */
721 # ifndef EXIM_HAVE_ECDH
723 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
727 if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve, errstr))
729 if (!exp_curve || !*exp_curve)
732 /* "auto" needs to be handled carefully.
733 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
734 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
735 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
736 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
737 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
739 if (Ustrcmp(exp_curve, "auto") == 0)
741 #if OPENSSL_VERSION_NUMBER < 0x10002000L
742 DEBUG(D_tls) debug_printf(
743 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
744 exp_curve = US"prime256v1";
746 # if defined SSL_CTRL_SET_ECDH_AUTO
747 DEBUG(D_tls) debug_printf(
748 "ECDH OpenSSL 1.0.2+: temp key parameter settings: autoselection\n");
749 SSL_CTX_set_ecdh_auto(sctx, 1);
752 DEBUG(D_tls) debug_printf(
753 "ECDH OpenSSL 1.1.0+: temp key parameter settings: default selection\n");
759 DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve);
760 if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef
761 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
762 && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef
766 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve),
771 # if OPENSSL_VERSION_NUMBER < 0x30000000L
774 if (!(ecdh = EC_KEY_new_by_curve_name(nid)))
776 tls_error(US"Unable to create ec curve", host, NULL, errstr);
780 /* The "tmp" in the name here refers to setting a temporary key
781 not to the stability of the interface. */
783 if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0))
784 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), host, NULL, errstr);
786 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve);
790 #else /* v 3.0.0 + */
792 if ((rv = SSL_CTX_set1_groups(sctx, &nid, 1)) == 0)
793 tls_error(string_sprintf("Error enabling '%s' group", exp_curve), host, NULL, errstr);
795 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' group\n", exp_curve);
801 # endif /*EXIM_HAVE_ECDH*/
802 #endif /*OPENSSL_NO_ECDH*/
807 /*************************************************
808 * Expand key and cert file specs *
809 *************************************************/
813 s SSL connection (not used)
817 Returns: pointer to generated key
821 rsa_callback(SSL *s, int export, int keylength)
824 #ifdef EXIM_HAVE_RSA_GENKEY_EX
825 BIGNUM *bn = BN_new();
828 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
830 #ifdef EXIM_HAVE_RSA_GENKEY_EX
831 if ( !BN_set_word(bn, (unsigned long)RSA_F4)
832 || !(rsa_key = RSA_new())
833 || !RSA_generate_key_ex(rsa_key, keylength, bn, NULL)
836 if (!(rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL)))
840 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
841 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
850 /* Create and install a selfsigned certificate, for use in server mode */
851 /*XXX we could arrange to call this during prelo for a null tls_certificate option.
852 The normal cache inval + relo will suffice.
853 Just need a timer for inval. */
856 tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr)
864 DEBUG(D_tls) debug_printf("TLS: generating selfsigned server cert\n");
865 where = US"allocating pkey";
866 if (!(pkey = EVP_PKEY_new()))
869 where = US"allocating cert";
870 if (!(x509 = X509_new()))
873 where = US"generating pkey";
874 if (!(rsa = rsa_callback(NULL, 0, 2048)))
877 where = US"assigning pkey";
878 if (!EVP_PKEY_assign_RSA(pkey, rsa))
881 X509_set_version(x509, 2); /* N+1 - version 3 */
882 ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
883 X509_gmtime_adj(X509_get_notBefore(x509), 0);
884 X509_gmtime_adj(X509_get_notAfter(x509), (long)2 * 60 * 60); /* 2 hour */
885 X509_set_pubkey(x509, pkey);
887 name = X509_get_subject_name(x509);
888 X509_NAME_add_entry_by_txt(name, "C",
889 MBSTRING_ASC, CUS "UK", -1, -1, 0);
890 X509_NAME_add_entry_by_txt(name, "O",
891 MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0);
892 X509_NAME_add_entry_by_txt(name, "CN",
893 MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0);
894 X509_set_issuer_name(x509, name);
896 where = US"signing cert";
897 if (!X509_sign(x509, pkey, EVP_md5()))
900 where = US"installing selfsign cert";
901 if (!SSL_CTX_use_certificate(sctx, x509))
904 where = US"installing selfsign key";
905 if (!SSL_CTX_use_PrivateKey(sctx, pkey))
911 (void) tls_error(where, NULL, NULL, errstr);
912 if (x509) X509_free(x509);
913 if (pkey) EVP_PKEY_free(pkey);
923 /*************************************************
924 * Information callback *
925 *************************************************/
927 /* The SSL library functions call this from time to time to indicate what they
928 are doing. We copy the string to the debugging output when TLS debugging has
940 info_callback(SSL *s, int where, int ret)
946 if (where & SSL_ST_CONNECT)
947 str = US"SSL_connect";
948 else if (where & SSL_ST_ACCEPT)
949 str = US"SSL_accept";
951 str = US"SSL info (undefined)";
953 if (where & SSL_CB_LOOP)
954 debug_printf("%s: %s\n", str, SSL_state_string_long(s));
955 else if (where & SSL_CB_ALERT)
956 debug_printf("SSL3 alert %s:%s:%s\n",
957 str = where & SSL_CB_READ ? US"read" : US"write",
958 SSL_alert_type_string_long(ret), SSL_alert_desc_string_long(ret));
959 else if (where & SSL_CB_EXIT)
962 debug_printf("%s: failed in %s\n", str, SSL_state_string_long(s));
964 debug_printf("%s: error in %s\n", str, SSL_state_string_long(s));
966 else if (where & SSL_CB_HANDSHAKE_START)
967 debug_printf("%s: hshake start: %s\n", str, SSL_state_string_long(s));
968 else if (where & SSL_CB_HANDSHAKE_DONE)
969 debug_printf("%s: hshake done: %s\n", str, SSL_state_string_long(s));
973 #ifdef OPENSSL_HAVE_KEYLOG_CB
975 keylog_callback(const SSL *ssl, const char *line)
979 DEBUG(D_tls) debug_printf("%.200s\n", line);
980 if (!(filename = getenv("SSLKEYLOGFILE"))) return;
981 if (!(fp = fopen(filename, "a"))) return;
982 fprintf(fp, "%s\n", line);
991 #ifndef DISABLE_EVENT
993 verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
994 BOOL *calledp, const BOOL *optionalp, const uschar * what)
1000 ev = tlsp == &tls_out ? client_static_state->event_action : event_action;
1003 DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth);
1004 old_cert = tlsp->peercert;
1005 tlsp->peercert = X509_dup(cert);
1006 /* NB we do not bother setting peerdn */
1007 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
1009 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
1010 "depth=%d cert=%s: %s",
1011 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1012 what, depth, dn, yield);
1016 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
1017 return 1; /* reject (leaving peercert set) */
1019 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
1020 "(host in tls_try_verify_hosts)\n");
1021 tlsp->verify_override = TRUE;
1023 X509_free(tlsp->peercert);
1024 tlsp->peercert = old_cert;
1030 /*************************************************
1031 * Callback for verification *
1032 *************************************************/
1034 /* The SSL library does certificate verification if set up to do so. This
1035 callback has the current yes/no state is in "state". If verification succeeded,
1036 we set the certificate-verified flag. If verification failed, what happens
1037 depends on whether the client is required to present a verifiable certificate
1040 If verification is optional, we change the state to yes, but still log the
1041 verification error. For some reason (it really would help to have proper
1042 documentation of OpenSSL), this callback function then gets called again, this
1043 time with state = 1. We must take care not to set the private verified flag on
1044 the second time through.
1046 Note: this function is not called if the client fails to present a certificate
1047 when asked. We get here only if a certificate has been received. Handling of
1048 optional verification for this case is done when requesting SSL to verify, by
1049 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
1051 May be called multiple times for different issues with a certificate, even
1052 for a given "depth" in the certificate chain.
1055 preverify_ok current yes/no state as 1/0
1056 x509ctx certificate information.
1057 tlsp per-direction (client vs. server) support data
1058 calledp has-been-called flag
1059 optionalp verification-is-optional flag
1061 Returns: 0 if verification should fail, otherwise 1
1065 verify_callback(int preverify_ok, X509_STORE_CTX * x509ctx,
1066 tls_support * tlsp, BOOL * calledp, BOOL * optionalp)
1068 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
1069 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
1072 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
1074 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
1075 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1076 tlsp == &tls_out ? deliver_host_address : sender_host_address);
1079 dn[sizeof(dn)-1] = '\0';
1081 tlsp->verify_override = FALSE;
1082 if (preverify_ok == 0)
1084 uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])",
1085 *verify_mode, sender_host_address)
1087 log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
1088 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1090 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn);
1094 if (!tlsp->peercert)
1095 tlsp->peercert = X509_dup(cert); /* record failing cert */
1096 return 0; /* reject */
1098 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
1099 "tls_try_verify_hosts)\n");
1100 tlsp->verify_override = TRUE;
1103 else if (depth != 0)
1105 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
1106 #ifndef DISABLE_OCSP
1107 if (tlsp == &tls_out && client_static_state->u_ocsp.client.verify_store)
1108 { /* client, wanting stapling */
1109 /* Add the server cert's signing chain as the one
1110 for the verification of the OCSP stapled information. */
1112 if (!X509_STORE_add_cert(client_static_state->u_ocsp.client.verify_store,
1115 sk_X509_push(client_static_state->verify_stack, cert);
1118 #ifndef DISABLE_EVENT
1119 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
1120 return 0; /* reject, with peercert set */
1125 const uschar * verify_cert_hostnames;
1127 if ( tlsp == &tls_out
1128 && ((verify_cert_hostnames = client_static_state->verify_cert_hostnames)))
1129 /* client, wanting hostname check */
1132 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
1133 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
1134 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
1136 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
1137 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
1140 const uschar * list = verify_cert_hostnames;
1143 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
1144 if ((rc = X509_check_host(cert, CCS name, 0,
1145 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
1146 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
1151 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1152 tlsp == &tls_out ? deliver_host_address : sender_host_address);
1159 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
1162 uschar * extra = verify_mode
1163 ? string_sprintf(" (during %c-verify for [%s])",
1164 *verify_mode, sender_host_address)
1166 log_write(0, LOG_MAIN,
1167 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
1168 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1169 extra, dn, verify_cert_hostnames);
1173 if (!tlsp->peercert)
1174 tlsp->peercert = X509_dup(cert); /* record failing cert */
1175 return 0; /* reject */
1177 DEBUG(D_tls) debug_printf("SSL verify name failure overridden (host in "
1178 "tls_try_verify_hosts)\n");
1179 tlsp->verify_override = TRUE;
1183 #ifndef DISABLE_EVENT
1184 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
1185 return 0; /* reject, with peercert set */
1188 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
1189 *calledp ? "" : " authenticated", dn);
1193 return 1; /* accept, at least for this level */
1197 verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
1199 return verify_callback(preverify_ok, x509ctx, &tls_out,
1200 &client_verify_callback_called, &client_verify_optional);
1204 verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
1206 return verify_callback(preverify_ok, x509ctx, &tls_in,
1207 &server_verify_callback_called, &server_verify_optional);
1213 /* This gets called *by* the dane library verify callback, which interposes
1217 verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
1219 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
1221 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
1222 #ifndef DISABLE_EVENT
1223 BOOL dummy_called, optional = FALSE;
1226 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
1228 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
1229 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1230 deliver_host_address);
1233 dn[sizeof(dn)-1] = '\0';
1235 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
1236 preverify_ok ? "ok":"BAD", depth, dn);
1238 #ifndef DISABLE_EVENT
1239 if (verify_event(&tls_out, cert, depth, dn,
1240 &dummy_called, &optional, US"DANE"))
1241 return 0; /* reject, with peercert set */
1244 if (preverify_ok == 1)
1246 tls_out.dane_verified = TRUE;
1247 #ifndef DISABLE_OCSP
1248 if (client_static_state->u_ocsp.client.verify_store)
1249 { /* client, wanting stapling */
1250 /* Add the server cert's signing chain as the one
1251 for the verification of the OCSP stapled information. */
1253 if (!X509_STORE_add_cert(client_static_state->u_ocsp.client.verify_store,
1256 sk_X509_push(client_static_state->verify_stack, cert);
1262 int err = X509_STORE_CTX_get_error(x509ctx);
1264 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
1265 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
1268 return preverify_ok;
1271 #endif /*SUPPORT_DANE*/
1274 #ifndef DISABLE_OCSP
1275 /*************************************************
1276 * Load OCSP information into state *
1277 *************************************************/
1278 /* Called to load the server OCSP response from the given file into memory, once
1279 caller has determined this is needed. Checks validity. Debugs a message
1282 ASSUMES: single response, for single cert.
1285 state various parts of session state
1286 filename the filename putatively holding an OCSP response
1287 is_pem file is PEM format; otherwise is DER
1291 ocsp_load_response(exim_openssl_state_st * state, const uschar * filename,
1295 OCSP_RESPONSE * resp;
1296 OCSP_BASICRESP * basic_response;
1297 OCSP_SINGLERESP * single_response;
1298 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
1299 STACK_OF(X509) * sk;
1300 unsigned long verify_flags;
1301 int status, reason, i;
1304 debug_printf("tls_ocsp_file (%s) '%s'\n", is_pem ? "PEM" : "DER", filename);
1306 if (!filename || !*filename) return;
1309 if (!(bio = BIO_new_file(CS filename, "rb")))
1311 log_write(0, LOG_MAIN|LOG_PANIC,
1312 "Failed to open OCSP response file \"%s\": %.100s",
1313 filename, ERR_reason_error_string(ERR_get_error()));
1319 uschar * data, * freep;
1322 if (!PEM_read_bio(bio, &dummy, &dummy, &data, &len))
1324 log_write(0, LOG_MAIN|LOG_PANIC, "Failed to read PEM file \"%s\": %.100s",
1325 filename, ERR_reason_error_string(ERR_get_error()));
1329 resp = d2i_OCSP_RESPONSE(NULL, CUSS &data, len);
1330 OPENSSL_free(freep);
1333 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
1338 log_write(0, LOG_MAIN|LOG_PANIC, "Error reading OCSP response from \"%s\": %s",
1339 filename, ERR_reason_error_string(ERR_get_error()));
1343 if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
1345 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
1346 OCSP_response_status_str(status), status);
1352 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1353 OCSP_RESPONSE_print(bp, resp, 0); /* extreme debug: stapling content */
1358 if (!(basic_response = OCSP_response_get1_basic(resp)))
1361 debug_printf("OCSP response parse error: unable to extract basic response.\n");
1365 sk = state->verify_stack;
1366 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
1368 /* May need to expose ability to adjust those flags?
1369 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
1370 OCSP_TRUSTOTHER OCSP_NOINTERN */
1372 /* This does a full verify on the OCSP proof before we load it for serving
1373 up; possibly overkill - just date-checks might be nice enough.
1375 OCSP_basic_verify takes a "store" arg, but does not
1376 use it for the chain verification, which is all we do
1377 when OCSP_NOVERIFY is set. The content from the wire
1378 "basic_response" and a cert-stack "sk" are all that is used.
1380 We have a stack, loaded in setup_certs() if tls_verify_certificates
1381 was a file (not a directory, or "system"). It is unfortunate we
1382 cannot used the connection context store, as that would neatly
1383 handle the "system" case too, but there seems to be no library
1384 function for getting a stack from a store.
1385 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
1386 We do not free the stack since it could be needed a second time for
1389 Separately we might try to replace using OCSP_basic_verify() - which seems to not
1390 be a public interface into the OpenSSL library (there's no manual entry) -
1391 But what with? We also use OCSP_basic_verify in the client stapling callback.
1392 And there we NEED it; we must verify that status... unless the
1393 library does it for us anyway? */
1395 if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0)
1399 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1400 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
1405 /* Here's the simplifying assumption: there's only one response, for the
1406 one certificate we use, and nothing for anything else in a chain. If this
1407 proves false, we need to extract a cert id from our issued cert
1408 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
1409 right cert in the stack and then calls OCSP_single_get0_status()).
1411 I'm hoping to avoid reworking a bunch more of how we handle state here.
1413 XXX that will change when we add support for (TLS1.3) whole-chain stapling
1416 if (!(single_response = OCSP_resp_get0(basic_response, 0)))
1419 debug_printf("Unable to get first response from OCSP basic response.\n");
1423 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
1424 if (status != V_OCSP_CERTSTATUS_GOOD)
1426 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
1427 OCSP_cert_status_str(status), status,
1428 OCSP_crl_reason_str(reason), reason);
1432 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1434 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
1439 /* Add the resp to the list used by tls_server_stapling_cb() */
1441 ocsp_resplist ** op = &state->u_ocsp.server.olist, * oentry;
1442 while (oentry = *op)
1444 *op = oentry = store_get(sizeof(ocsp_resplist), FALSE);
1445 oentry->next = NULL;
1446 oentry->resp = resp;
1451 if (f.running_in_test_harness)
1453 extern char ** environ;
1454 if (environ) for (uschar ** p = USS environ; *p; p++)
1455 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1457 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
1458 goto supply_response;
1466 ocsp_free_response_list(exim_openssl_state_st * cbinfo)
1468 for (ocsp_resplist * olist = cbinfo->u_ocsp.server.olist; olist;
1469 olist = olist->next)
1470 OCSP_RESPONSE_free(olist->resp);
1471 cbinfo->u_ocsp.server.olist = NULL;
1473 #endif /*!DISABLE_OCSP*/
1480 tls_add_certfile(SSL_CTX * sctx, exim_openssl_state_st * cbinfo, uschar * file,
1483 DEBUG(D_tls) debug_printf("tls_certificate file '%s'\n", file);
1484 if (!SSL_CTX_use_certificate_chain_file(sctx, CS file))
1485 return tls_error(string_sprintf(
1486 "SSL_CTX_use_certificate_chain_file file=%s", file),
1487 cbinfo->host, NULL, errstr);
1492 tls_add_pkeyfile(SSL_CTX * sctx, exim_openssl_state_st * cbinfo, uschar * file,
1495 DEBUG(D_tls) debug_printf("tls_privatekey file '%s'\n", file);
1496 if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM))
1497 return tls_error(string_sprintf(
1498 "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr);
1505 /* Called once during tls_init and possibly again during TLS setup, for a
1506 new context, if Server Name Indication was used and tls_sni was seen in
1507 the certificate string.
1510 sctx the SSL_CTX* to update
1511 state various parts of session state
1512 errstr error string pointer
1514 Returns: OK/DEFER/FAIL
1518 tls_expand_session_files(SSL_CTX * sctx, exim_openssl_state_st * state,
1523 if (!state->certificate)
1525 if (!state->is_server) /* client */
1528 if (tls_install_selfsign(sctx, errstr) != OK)
1535 if ( !reexpand_tls_files_for_sni
1536 && ( Ustrstr(state->certificate, US"tls_sni")
1537 || Ustrstr(state->certificate, US"tls_in_sni")
1538 || Ustrstr(state->certificate, US"tls_out_sni")
1540 reexpand_tls_files_for_sni = TRUE;
1542 if (!expand_check(state->certificate, US"tls_certificate", &expanded, errstr))
1546 if (state->is_server)
1548 const uschar * file_list = expanded;
1551 #ifndef DISABLE_OCSP
1552 const uschar * olist = state->u_ocsp.server.file;
1555 BOOL fmt_pem = FALSE;
1558 if (!expand_check(olist, US"tls_ocsp_file", USS &olist, errstr))
1560 if (olist && !*olist)
1563 if ( state->u_ocsp.server.file_expanded && olist
1564 && (Ustrcmp(olist, state->u_ocsp.server.file_expanded) == 0))
1566 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
1571 ocsp_free_response_list(state);
1572 state->u_ocsp.server.file_expanded = olist;
1576 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1578 if ((err = tls_add_certfile(sctx, state, file, errstr)))
1581 #ifndef DISABLE_OCSP
1583 if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1585 if (Ustrncmp(ofile, US"PEM ", 4) == 0)
1590 else if (Ustrncmp(ofile, US"DER ", 4) == 0)
1595 ocsp_load_response(state, ofile, fmt_pem);
1598 DEBUG(D_tls) debug_printf("ran out of ocsp file list\n");
1602 else /* would there ever be a need for multiple client certs? */
1603 if ((err = tls_add_certfile(sctx, state, expanded, errstr)))
1606 if ( state->privatekey
1607 && !expand_check(state->privatekey, US"tls_privatekey", &expanded, errstr))
1610 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1611 of the expansion is an empty string, ignore it also, and assume the private
1612 key is in the same file as the certificate. */
1614 if (expanded && *expanded)
1615 if (state->is_server)
1617 const uschar * file_list = expanded;
1621 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1622 if ((err = tls_add_pkeyfile(sctx, state, file, errstr)))
1625 else /* would there ever be a need for multiple client certs? */
1626 if ((err = tls_add_pkeyfile(sctx, state, expanded, errstr)))
1636 /**************************************************
1637 * One-time init credentials for server and client *
1638 **************************************************/
1641 server_load_ciphers(SSL_CTX * ctx, exim_openssl_state_st * state,
1642 uschar * ciphers, uschar ** errstr)
1644 for (uschar * s = ciphers; *s; s++ ) if (*s == '_') *s = '-';
1645 DEBUG(D_tls) debug_printf("required ciphers: %s\n", ciphers);
1646 if (!SSL_CTX_set_cipher_list(ctx, CS ciphers))
1647 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
1648 state->server_cipher_list = ciphers;
1655 lib_ctx_new(SSL_CTX ** ctxp, host_item * host, uschar ** errstr)
1658 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1659 if (!(ctx = SSL_CTX_new(host ? TLS_client_method() : TLS_server_method())))
1661 if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
1663 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
1665 /* Set up the information callback, which outputs if debugging is at a suitable
1670 SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
1671 #if defined(EXIM_HAVE_OPESSL_TRACE) && !defined(OPENSSL_NO_SSL_TRACE)
1672 /* this needs a debug build of OpenSSL */
1673 SSL_CTX_set_msg_callback(ctx, (void (*)())SSL_trace);
1675 #ifdef OPENSSL_HAVE_KEYLOG_CB
1676 SSL_CTX_set_keylog_callback(ctx, (void (*)())keylog_callback);
1680 /* Automatically re-try reads/writes after renegotiation. */
1681 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
1688 tls_server_creds_init(void)
1691 uschar * dummy_errstr;
1692 unsigned lifetime = 0;
1696 state_server.lib_state = null_tls_preload;
1698 if (lib_ctx_new(&ctx, NULL, &dummy_errstr) != OK)
1700 state_server.lib_state.lib_ctx = ctx;
1702 /* Preload DH params and EC curve */
1704 if (opt_unset_or_noexpand(tls_dhparam))
1706 DEBUG(D_tls) debug_printf("TLS: preloading DH params for server\n");
1707 if (init_dh(ctx, tls_dhparam, NULL, &dummy_errstr))
1708 state_server.lib_state.dh = TRUE;
1710 if (opt_unset_or_noexpand(tls_eccurve))
1712 DEBUG(D_tls) debug_printf("TLS: preloading ECDH curve for server\n");
1713 if (init_ecdh(ctx, NULL, &dummy_errstr))
1714 state_server.lib_state.ecdh = TRUE;
1717 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1718 /* If we can, preload the server-side cert, key and ocsp */
1720 if ( opt_set_and_noexpand(tls_certificate)
1721 # ifndef DISABLE_OCSP
1722 && opt_unset_or_noexpand(tls_ocsp_file)
1724 && opt_unset_or_noexpand(tls_privatekey))
1726 /* Set watches on the filenames. The implementation does de-duplication
1727 so we can just blindly do them all. */
1729 if ( tls_set_watch(tls_certificate, TRUE)
1730 # ifndef DISABLE_OCSP
1731 && tls_set_watch(tls_ocsp_file, TRUE)
1733 && tls_set_watch(tls_privatekey, TRUE))
1735 state_server.certificate = tls_certificate;
1736 state_server.privatekey = tls_privatekey;
1737 #ifndef DISABLE_OCSP
1738 state_server.u_ocsp.server.file = tls_ocsp_file;
1741 DEBUG(D_tls) debug_printf("TLS: preloading server certs\n");
1742 if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
1743 state_server.lib_state.conn_certs = TRUE;
1746 else if ( !tls_certificate && !tls_privatekey
1747 # ifndef DISABLE_OCSP
1751 { /* Generate & preload a selfsigned cert. No files to watch. */
1752 if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
1754 state_server.lib_state.conn_certs = TRUE;
1755 lifetime = f.running_in_test_harness ? 2 : 60 * 60; /* 1 hour */
1759 DEBUG(D_tls) debug_printf("TLS: not preloading server certs\n");
1762 /* If we can, preload the Authorities for checking client certs against.
1763 Actual choice to do verify is made (tls_{,try_}verify_hosts)
1764 at TLS conn startup */
1766 if ( opt_set_and_noexpand(tls_verify_certificates)
1767 && opt_unset_or_noexpand(tls_crl))
1769 /* Watch the default dir also as they are always included */
1771 if ( tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
1772 && tls_set_watch(tls_verify_certificates, FALSE)
1773 && tls_set_watch(tls_crl, FALSE))
1775 DEBUG(D_tls) debug_printf("TLS: preloading CA bundle for server\n");
1777 if (setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, &dummy_errstr)
1779 state_server.lib_state.cabundle = TRUE;
1783 DEBUG(D_tls) debug_printf("TLS: not preloading CA bundle for server\n");
1784 #endif /* EXIM_HAVE_INOTIFY */
1787 /* If we can, preload the ciphers control string */
1789 if (opt_set_and_noexpand(tls_require_ciphers))
1791 DEBUG(D_tls) debug_printf("TLS: preloading cipher list for server\n");
1792 if (server_load_ciphers(ctx, &state_server, tls_require_ciphers,
1793 &dummy_errstr) == OK)
1794 state_server.lib_state.pri_string = TRUE;
1797 DEBUG(D_tls) debug_printf("TLS: not preloading cipher list for server\n");
1804 /* Preload whatever creds are static, onto a transport. The client can then
1805 just copy the pointer as it starts up.
1806 Called from the daemon after a cache-invalidate with watch set; called from
1807 a queue-run startup with watch clear. */
1810 tls_client_creds_init(transport_instance * t, BOOL watch)
1812 smtp_transport_options_block * ob = t->options_block;
1813 exim_openssl_state_st tpt_dummy_state;
1814 host_item * dummy_host = (host_item *)1;
1815 uschar * dummy_errstr;
1820 ob->tls_preload = null_tls_preload;
1821 if (lib_ctx_new(&ctx, dummy_host, &dummy_errstr) != OK)
1823 ob->tls_preload.lib_ctx = ctx;
1825 tpt_dummy_state.lib_state = ob->tls_preload;
1827 if (opt_unset_or_noexpand(tls_dhparam))
1829 DEBUG(D_tls) debug_printf("TLS: preloading DH params for transport '%s'\n", t->name);
1830 if (init_dh(ctx, tls_dhparam, NULL, &dummy_errstr))
1831 ob->tls_preload.dh = TRUE;
1833 if (opt_unset_or_noexpand(tls_eccurve))
1835 DEBUG(D_tls) debug_printf("TLS: preloading ECDH curve for transport '%s'\n", t->name);
1836 if (init_ecdh(ctx, NULL, &dummy_errstr))
1837 ob->tls_preload.ecdh = TRUE;
1840 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1841 if ( opt_set_and_noexpand(ob->tls_certificate)
1842 && opt_unset_or_noexpand(ob->tls_privatekey))
1845 || ( tls_set_watch(ob->tls_certificate, FALSE)
1846 && tls_set_watch(ob->tls_privatekey, FALSE)
1849 uschar * pkey = ob->tls_privatekey;
1852 debug_printf("TLS: preloading client certs for transport '%s'\n",t->name);
1854 if ( tls_add_certfile(ctx, &tpt_dummy_state, ob->tls_certificate,
1856 && tls_add_pkeyfile(ctx, &tpt_dummy_state,
1857 pkey ? pkey : ob->tls_certificate,
1860 ob->tls_preload.conn_certs = TRUE;
1865 debug_printf("TLS: not preloading client certs, for transport '%s'\n", t->name);
1868 if ( opt_set_and_noexpand(ob->tls_verify_certificates)
1869 && opt_unset_or_noexpand(ob->tls_crl))
1872 || tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
1873 && tls_set_watch(ob->tls_verify_certificates, FALSE)
1874 && tls_set_watch(ob->tls_crl, FALSE)
1878 debug_printf("TLS: preloading CA bundle for transport '%s'\n", t->name);
1880 if (setup_certs(ctx, ob->tls_verify_certificates,
1881 ob->tls_crl, dummy_host, &dummy_errstr) == OK)
1882 ob->tls_preload.cabundle = TRUE;
1887 debug_printf("TLS: not preloading CA bundle, for transport '%s'\n", t->name);
1889 #endif /*EXIM_HAVE_INOTIFY*/
1893 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1894 /* Invalidate the creds cached, by dropping the current ones.
1895 Call when we notice one of the source files has changed. */
1898 tls_server_creds_invalidate(void)
1900 SSL_CTX_free(state_server.lib_state.lib_ctx);
1901 state_server.lib_state = null_tls_preload;
1906 tls_client_creds_invalidate(transport_instance * t)
1908 smtp_transport_options_block * ob = t->options_block;
1909 SSL_CTX_free(ob->tls_preload.lib_ctx);
1910 ob->tls_preload = null_tls_preload;
1916 tls_server_creds_invalidate(void)
1920 tls_client_creds_invalidate(transport_instance * t)
1923 #endif /*EXIM_HAVE_INOTIFY*/
1927 #ifndef DISABLE_OCSP
1929 x509_store_dump_cert_s_names(X509_STORE * store)
1931 STACK_OF(X509_OBJECT) * roots= store->objs;
1932 static uschar name[256];
1934 for (int i= 0; i < sk_X509_OBJECT_num(roots); i++)
1936 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
1937 if(tmp_obj->type == X509_LU_X509)
1939 X509_NAME * sn = X509_get_subject_name(tmp_obj->data.x509);
1940 if (X509_NAME_oneline(sn, CS name, sizeof(name)))
1942 name[sizeof(name)-1] = '\0';
1943 debug_printf(" %s\n", name);
1952 #ifndef DISABLE_TLS_RESUME
1953 /* Manage the keysets used for encrypting the session tickets, on the server. */
1955 typedef struct { /* Session ticket encryption key */
1958 const EVP_CIPHER * aes_cipher;
1959 uschar aes_key[32]; /* size needed depends on cipher. aes_128 implies 128/8 = 16? */
1960 const EVP_MD * hmac_hash;
1961 uschar hmac_key[16];
1966 static exim_stek exim_tk; /* current key */
1967 static exim_stek exim_tk_old; /* previous key */
1972 time_t t = time(NULL);
1974 if (exim_tk.name[0])
1976 if (exim_tk.renew >= t) return;
1977 exim_tk_old = exim_tk;
1980 if (f.running_in_test_harness) ssl_session_timeout = 6;
1982 DEBUG(D_tls) debug_printf("OpenSSL: %s STEK\n", exim_tk.name[0] ? "rotating" : "creating");
1983 if (RAND_bytes(exim_tk.aes_key, sizeof(exim_tk.aes_key)) <= 0) return;
1984 if (RAND_bytes(exim_tk.hmac_key, sizeof(exim_tk.hmac_key)) <= 0) return;
1985 if (RAND_bytes(exim_tk.name+1, sizeof(exim_tk.name)-1) <= 0) return;
1987 exim_tk.name[0] = 'E';
1988 exim_tk.aes_cipher = EVP_aes_256_cbc();
1989 exim_tk.hmac_hash = EVP_sha256();
1990 exim_tk.expire = t + ssl_session_timeout;
1991 exim_tk.renew = t + ssl_session_timeout/2;
1997 if (!exim_tk.name[0]) return NULL;
2002 tk_find(const uschar * name)
2004 return memcmp(name, exim_tk.name, sizeof(exim_tk.name)) == 0 ? &exim_tk
2005 : memcmp(name, exim_tk_old.name, sizeof(exim_tk_old.name)) == 0 ? &exim_tk_old
2009 /* Callback for session tickets, on server */
2011 ticket_key_callback(SSL * ssl, uschar key_name[16],
2012 uschar * iv, EVP_CIPHER_CTX * c_ctx, HMAC_CTX * hctx, int enc)
2014 tls_support * tlsp = state_server.tlsp;
2019 DEBUG(D_tls) debug_printf("ticket_key_callback: create new session\n");
2020 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
2022 if (RAND_bytes(iv, EVP_MAX_IV_LENGTH) <= 0)
2023 return -1; /* insufficient random */
2025 if (!(key = tk_current())) /* current key doesn't exist or isn't valid */
2026 return 0; /* key couldn't be created */
2027 memcpy(key_name, key->name, 16);
2028 DEBUG(D_tls) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - time(NULL));
2030 /*XXX will want these dependent on the ssl session strength */
2031 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
2032 key->hmac_hash, NULL);
2033 EVP_EncryptInit_ex(c_ctx, key->aes_cipher, NULL, key->aes_key, iv);
2035 DEBUG(D_tls) debug_printf("ticket created\n");
2040 time_t now = time(NULL);
2042 DEBUG(D_tls) debug_printf("ticket_key_callback: retrieve session\n");
2043 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
2045 if (!(key = tk_find(key_name)) || key->expire < now)
2049 debug_printf("ticket not usable (%s)\n", key ? "expired" : "not found");
2050 if (key) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - now);
2055 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
2056 key->hmac_hash, NULL);
2057 EVP_DecryptInit_ex(c_ctx, key->aes_cipher, NULL, key->aes_key, iv);
2059 DEBUG(D_tls) debug_printf("ticket usable, STEK expire " TIME_T_FMT "\n", key->expire - now);
2061 /* The ticket lifetime and renewal are the same as the STEK lifetime and
2062 renewal, which is overenthusiastic. A factor of, say, 3x longer STEK would
2063 be better. To do that we'd have to encode ticket lifetime in the name as
2064 we don't yet see the restored session. Could check posthandshake for TLS1.3
2065 and trigger a new ticket then, but cannot do that for TLS1.2 */
2066 return key->renew < now ? 2 : 1;
2074 setup_cert_verify(SSL_CTX * ctx, BOOL optional,
2075 int (*cert_vfy_cb)(int, X509_STORE_CTX *))
2077 /* If verification is optional, don't fail if no certificate */
2079 SSL_CTX_set_verify(ctx,
2080 SSL_VERIFY_PEER | (optional ? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
2085 /*************************************************
2086 * Callback to handle SNI *
2087 *************************************************/
2089 /* Called when acting as server during the TLS session setup if a Server Name
2090 Indication extension was sent by the client.
2092 API documentation is OpenSSL s_server.c implementation.
2095 s SSL* of the current session
2096 ad unknown (part of OpenSSL API) (unused)
2097 arg Callback of "our" registered data
2099 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
2101 XXX might need to change to using ClientHello callback,
2102 per https://www.openssl.org/docs/manmaster/man3/SSL_client_hello_cb_fn.html
2105 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2107 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
2109 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
2110 exim_openssl_state_st *state = (exim_openssl_state_st *) arg;
2112 int old_pool = store_pool;
2113 uschar * dummy_errstr;
2116 return SSL_TLSEXT_ERR_OK;
2118 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
2119 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
2121 /* Make the extension value available for expansion */
2122 store_pool = POOL_PERM;
2123 tls_in.sni = string_copy_taint(US servername, TRUE);
2124 store_pool = old_pool;
2126 if (!reexpand_tls_files_for_sni)
2127 return SSL_TLSEXT_ERR_OK;
2129 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
2130 not confident that memcpy wouldn't break some internal reference counting.
2131 Especially since there's a references struct member, which would be off. */
2133 if (lib_ctx_new(&server_sni, NULL, &dummy_errstr) != OK)
2136 /* Not sure how many of these are actually needed, since SSL object
2137 already exists. Might even need this selfsame callback, for reneg? */
2140 SSL_CTX * ctx = state_server.lib_state.lib_ctx;
2141 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(ctx));
2142 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(ctx));
2143 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(ctx));
2144 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(ctx));
2145 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
2146 SSL_CTX_set_tlsext_servername_arg(server_sni, state);
2149 if ( !init_dh(server_sni, state->dhparam, NULL, &dummy_errstr)
2150 || !init_ecdh(server_sni, NULL, &dummy_errstr)
2154 if ( state->server_cipher_list
2155 && !SSL_CTX_set_cipher_list(server_sni, CS state->server_cipher_list))
2158 #ifndef DISABLE_OCSP
2159 if (state->u_ocsp.server.file)
2161 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
2162 SSL_CTX_set_tlsext_status_arg(server_sni, state);
2168 if ( !expand_check(tls_verify_certificates, US"tls_verify_certificates",
2169 &expcerts, &dummy_errstr)
2170 || (rc = setup_certs(server_sni, expcerts, tls_crl, NULL,
2171 &dummy_errstr)) != OK)
2174 if (expcerts && *expcerts)
2175 setup_cert_verify(server_sni, FALSE, verify_callback_server);
2178 /* do this after setup_certs, because this can require the certs for verifying
2179 OCSP information. */
2180 if ((rc = tls_expand_session_files(server_sni, state, &dummy_errstr)) != OK)
2183 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
2184 SSL_set_SSL_CTX(s, server_sni);
2185 return SSL_TLSEXT_ERR_OK;
2187 bad: return SSL_TLSEXT_ERR_ALERT_FATAL;
2189 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
2194 #ifdef EXIM_HAVE_ALPN
2195 /*************************************************
2196 * Callback to handle ALPN *
2197 *************************************************/
2199 /* Called on server if tls_alpn nonblank after expansion,
2200 when client offers ALPN, after the SNI callback.
2201 If set and not matching the list then we dump the connection */
2204 tls_server_alpn_cb(SSL *ssl, const uschar ** out, uschar * outlen,
2205 const uschar * in, unsigned int inlen, void * arg)
2207 server_seen_alpn = TRUE;
2210 debug_printf("Received TLS ALPN offer:");
2211 for (int pos = 0, siz; pos < inlen; pos += siz+1)
2214 if (pos + 1 + siz > inlen) siz = inlen - pos - 1;
2215 debug_printf(" '%.*s'", siz, in + pos + 1);
2217 debug_printf(". Our list: '%s'\n", tls_alpn);
2220 /* Look for an acceptable ALPN */
2222 if ( inlen > 1 /* at least one name */
2223 && in[0]+1 == inlen /* filling the vector, so exactly one name */
2226 const uschar * list = tls_alpn;
2228 for (uschar * name; name = string_nextinlist(&list, &sep, NULL, 0); )
2229 if (Ustrncmp(in+1, name, in[0]) == 0)
2231 *out = in+1; /* we checked for exactly one, so can just point to it */
2233 return SSL_TLSEXT_ERR_OK; /* use ALPN */
2237 /* More than one name from clilent, or name did not match our list. */
2239 /* This will be fatal to the TLS conn; would be nice to kill TCP also.
2240 Maybe as an option in future; for now leave control to the config (must-tls). */
2242 DEBUG(D_tls) debug_printf("TLS ALPN rejected\n");
2243 return SSL_TLSEXT_ERR_ALERT_FATAL;
2245 #endif /* EXIM_HAVE_ALPN */
2249 #ifndef DISABLE_OCSP
2251 /*************************************************
2252 * Callback to handle OCSP Stapling *
2253 *************************************************/
2255 /* Called when acting as server during the TLS session setup if the client
2256 requests OCSP information with a Certificate Status Request.
2258 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
2264 tls_server_stapling_cb(SSL *s, void *arg)
2266 const exim_openssl_state_st * state = arg;
2267 ocsp_resplist * olist = state->u_ocsp.server.olist;
2268 uschar * response_der; /*XXX blob */
2269 int response_der_len;
2272 debug_printf("Received TLS status request (OCSP stapling); %s response list\n",
2273 olist ? "have" : "lack");
2275 tls_in.ocsp = OCSP_NOT_RESP;
2277 return SSL_TLSEXT_ERR_NOACK;
2279 #ifdef EXIM_HAVE_OPESSL_GET0_SERIAL
2281 const X509 * cert_sent = SSL_get_certificate(s);
2282 const ASN1_INTEGER * cert_serial = X509_get0_serialNumber(cert_sent);
2283 const BIGNUM * cert_bn = ASN1_INTEGER_to_BN(cert_serial, NULL);
2285 for (; olist; olist = olist->next)
2287 OCSP_BASICRESP * bs = OCSP_response_get1_basic(olist->resp);
2288 const OCSP_SINGLERESP * single = OCSP_resp_get0(bs, 0);
2289 const OCSP_CERTID * cid = OCSP_SINGLERESP_get0_id(single);
2290 ASN1_INTEGER * res_cert_serial;
2291 const BIGNUM * resp_bn;
2292 ASN1_OCTET_STRING * res_cert_iNameHash;
2295 (void) OCSP_id_get0_info(&res_cert_iNameHash, NULL, NULL, &res_cert_serial,
2296 (OCSP_CERTID *) cid);
2297 resp_bn = ASN1_INTEGER_to_BN(res_cert_serial, NULL);
2301 debug_printf("cert serial: %s\n", BN_bn2hex(cert_bn));
2302 debug_printf("resp serial: %s\n", BN_bn2hex(resp_bn));
2305 if (BN_cmp(cert_bn, resp_bn) == 0)
2307 DEBUG(D_tls) debug_printf("matched serial for ocsp\n");
2309 /*XXX TODO: check the rest of the list for duplicate matches.
2310 If any, need to also check the Issuer Name hash.
2311 Without this, we will provide the wrong status in the case of
2316 DEBUG(D_tls) debug_printf("not match serial for ocsp\n");
2320 DEBUG(D_tls) debug_printf("failed to find match for ocsp\n");
2321 return SSL_TLSEXT_ERR_NOACK;
2327 DEBUG(D_tls) debug_printf("OpenSSL version too early to support multi-leaf OCSP\n");
2328 return SSL_TLSEXT_ERR_NOACK;
2332 /*XXX could we do the i2d earlier, rather than during the callback? */
2333 response_der = NULL;
2334 response_der_len = i2d_OCSP_RESPONSE(olist->resp, &response_der);
2335 if (response_der_len <= 0)
2336 return SSL_TLSEXT_ERR_NOACK;
2338 SSL_set_tlsext_status_ocsp_resp(state_server.lib_state.lib_ssl,
2339 response_der, response_der_len);
2340 tls_in.ocsp = OCSP_VFIED;
2341 return SSL_TLSEXT_ERR_OK;
2346 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
2348 BIO_printf(bp, "\t%s: ", str);
2349 ASN1_GENERALIZEDTIME_print(bp, time);
2354 tls_client_stapling_cb(SSL *s, void *arg)
2356 exim_openssl_state_st * cbinfo = arg;
2357 const unsigned char * p;
2359 OCSP_RESPONSE * rsp;
2360 OCSP_BASICRESP * bs;
2363 DEBUG(D_tls) debug_printf("Received TLS status callback (OCSP stapling):\n");
2364 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
2367 /* Expect this when we requested ocsp but got none */
2368 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
2369 log_write(0, LOG_MAIN, "Required TLS certificate status not received");
2371 DEBUG(D_tls) debug_printf(" null\n");
2372 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2375 if (!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
2377 tls_out.ocsp = OCSP_FAILED; /*XXX should use tlsp-> to permit concurrent outbound */
2378 if (LOGGING(tls_cipher))
2379 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
2381 DEBUG(D_tls) debug_printf(" parse error\n");
2385 if (!(bs = OCSP_response_get1_basic(rsp)))
2387 tls_out.ocsp = OCSP_FAILED;
2388 if (LOGGING(tls_cipher))
2389 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
2391 DEBUG(D_tls) debug_printf(" error parsing response\n");
2392 OCSP_RESPONSE_free(rsp);
2396 /* We'd check the nonce here if we'd put one in the request. */
2397 /* However that would defeat cacheability on the server so we don't. */
2399 /* This section of code reworked from OpenSSL apps source;
2400 The OpenSSL Project retains copyright:
2401 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
2405 #ifndef EXIM_HAVE_OCSP_RESP_COUNT
2406 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
2409 DEBUG(D_tls) bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
2411 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
2413 /* Use the chain that verified the server cert to verify the stapled info */
2414 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
2416 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
2417 cbinfo->u_ocsp.client.verify_store, OCSP_NOEXPLICIT)) <= 0)
2418 if (ERR_peek_error())
2420 tls_out.ocsp = OCSP_FAILED;
2421 if (LOGGING(tls_cipher)) log_write(0, LOG_MAIN,
2422 "Received TLS cert status response, itself unverifiable: %s",
2423 ERR_reason_error_string(ERR_peek_error()));
2424 BIO_printf(bp, "OCSP response verify failure\n");
2425 ERR_print_errors(bp);
2426 OCSP_RESPONSE_print(bp, rsp, 0);
2430 DEBUG(D_tls) debug_printf("no explicit trust for OCSP signing"
2431 " in the root CA certificate; ignoring\n");
2433 DEBUG(D_tls) debug_printf("OCSP response well-formed and signed OK\n");
2435 /*XXX So we have a good stapled OCSP status. How do we know
2436 it is for the cert of interest? OpenSSL 1.1.0 has a routine
2437 OCSP_resp_find_status() which matches on a cert id, which presumably
2438 we should use. Making an id needs OCSP_cert_id_new(), which takes
2439 issuerName, issuerKey, serialNumber. Are they all in the cert?
2441 For now, carry on blindly accepting the resp. */
2444 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
2445 OCSP_resp_count(bs) - 1;
2447 sk_OCSP_SINGLERESP_num(sresp) - 1;
2451 OCSP_SINGLERESP * single = OCSP_resp_get0(bs, idx);
2453 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
2455 /*XXX so I can see putting a loop in here to handle a rsp with >1 singleresp
2456 - but what happens with a GnuTLS-style input?
2458 we could do with a debug label for each singleresp
2459 - it has a certID with a serialNumber, but I see no API to get that
2461 status = OCSP_single_get0_status(single, &reason, &rev,
2462 &thisupd, &nextupd);
2464 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
2465 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
2466 if (!OCSP_check_validity(thisupd, nextupd,
2467 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
2469 tls_out.ocsp = OCSP_FAILED;
2470 DEBUG(D_tls) ERR_print_errors(bp);
2471 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
2475 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
2476 OCSP_cert_status_str(status));
2479 case V_OCSP_CERTSTATUS_GOOD:
2480 continue; /* the idx loop */
2481 case V_OCSP_CERTSTATUS_REVOKED:
2482 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
2483 reason != -1 ? "; reason: " : "",
2484 reason != -1 ? OCSP_crl_reason_str(reason) : "");
2485 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
2488 log_write(0, LOG_MAIN,
2489 "Server certificate status unknown, in OCSP stapling");
2497 tls_out.ocsp = OCSP_VFIED;
2501 tls_out.ocsp = OCSP_FAILED;
2502 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2507 OCSP_RESPONSE_free(rsp);
2510 #endif /*!DISABLE_OCSP*/
2513 /*************************************************
2514 * Initialize for TLS *
2515 *************************************************/
2516 /* Called from both server and client code, to do preliminary initialization
2517 of the library. We allocate and return a context structure.
2520 host connected host, if client; NULL if server
2521 ob transport options block, if client; NULL if server
2522 ocsp_file file of stapling info (server); flag for require ocsp (client)
2523 addr address if client; NULL if server (for some randomness)
2524 caller_state place to put pointer to allocated state-struct
2525 errstr error string pointer
2527 Returns: OK/DEFER/FAIL
2531 tls_init(host_item * host, smtp_transport_options_block * ob,
2532 #ifndef DISABLE_OCSP
2535 address_item *addr, exim_openssl_state_st ** caller_state,
2540 exim_openssl_state_st * state;
2543 if (host) /* client */
2545 state = store_malloc(sizeof(exim_openssl_state_st));
2546 memset(state, 0, sizeof(*state));
2547 state->certificate = ob->tls_certificate;
2548 state->privatekey = ob->tls_privatekey;
2549 state->is_server = FALSE;
2550 state->dhparam = NULL;
2551 state->lib_state = ob->tls_preload;
2555 state = &state_server;
2556 state->certificate = tls_certificate;
2557 state->privatekey = tls_privatekey;
2558 state->is_server = TRUE;
2559 state->dhparam = tls_dhparam;
2560 state->lib_state = state_server.lib_state;
2566 if (!state->lib_state.pri_string)
2567 state->server_cipher_list = NULL;
2569 #ifndef DISABLE_EVENT
2570 state->event_action = NULL;
2575 /* It turns out that we need to seed the random number generator this early in
2576 order to get the full complement of ciphers to work. It took me roughly a day
2577 of work to discover this by experiment.
2579 On systems that have /dev/urandom, SSL may automatically seed itself from
2580 there. Otherwise, we have to make something up as best we can. Double check
2583 Although we likely called this before, at daemon startup, this is a chance
2584 to mix in further variable info (time, pid) if needed. */
2586 if (!lib_rand_init(addr))
2587 return tls_error(US"RAND_status", host,
2588 US"unable to seed random number generator", errstr);
2590 /* Apply administrator-supplied work-arounds.
2591 Historically we applied just one requested option,
2592 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
2593 moved to an administrator-controlled list of options to specify and
2594 grandfathered in the first one as the default value for "openssl_options".
2596 No OpenSSL version number checks: the options we accept depend upon the
2597 availability of the option value macros from OpenSSL. */
2600 if (!tls_openssl_options_parse(openssl_options, &init_options))
2601 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
2603 /* Create a context.
2604 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
2605 negotiation in the different methods; as far as I can tell, the only
2606 *_{server,client}_method which allows negotiation is SSLv23, which exists even
2607 when OpenSSL is built without SSLv2 support.
2608 By disabling with openssl_options, we can let admins re-enable with the
2611 if (!(ctx = state->lib_state.lib_ctx))
2613 if ((rc = lib_ctx_new(&ctx, host, errstr)) != OK)
2615 state->lib_state.lib_ctx = ctx;
2618 #ifndef DISABLE_TLS_RESUME
2619 tlsp->resumption = RESUME_SUPPORTED;
2623 #ifndef DISABLE_TLS_RESUME
2624 /* Should the server offer session resumption? */
2625 if (!host && verify_check_host(&tls_resumption_hosts) == OK)
2627 DEBUG(D_tls) debug_printf("tls_resumption_hosts overrides openssl_options\n");
2628 init_options &= ~SSL_OP_NO_TICKET;
2629 tlsp->resumption |= RESUME_SERVER_TICKET; /* server will give ticket on request */
2630 tlsp->host_resumable = TRUE;
2634 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
2635 if (!(SSL_CTX_set_options(ctx, init_options)))
2636 return tls_error(string_sprintf(
2637 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
2640 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
2642 /* We'd like to disable session cache unconditionally, but foolish Outlook
2643 Express clients then give up the first TLS connection and make a second one
2644 (which works). Only when there is an IMAP service on the same machine.
2645 Presumably OE is trying to use the cache for A on B. Leave it enabled for
2646 now, until we work out a decent way of presenting control to the config. It
2647 will never be used because we use a new context every time. */
2649 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
2652 /* Initialize with DH parameters if supplied */
2653 /* Initialize ECDH temp key parameter selection */
2655 if (state->lib_state.dh)
2656 { DEBUG(D_tls) debug_printf("TLS: DH params were preloaded\n"); }
2658 if (!init_dh(ctx, state->dhparam, host, errstr)) return DEFER;
2660 if (state->lib_state.ecdh)
2661 { DEBUG(D_tls) debug_printf("TLS: ECDH curve was preloaded\n"); }
2663 if (!init_ecdh(ctx, host, errstr)) return DEFER;
2665 /* Set up certificate and key (and perhaps OCSP info) */
2667 if (state->lib_state.conn_certs)
2670 debug_printf("TLS: %s certs were preloaded\n", host ? "client":"server");
2674 #ifndef DISABLE_OCSP
2677 state->u_ocsp.server.file = ocsp_file;
2678 state->u_ocsp.server.file_expanded = NULL;
2679 state->u_ocsp.server.olist = NULL;
2682 if ((rc = tls_expand_session_files(ctx, state, errstr)) != OK) return rc;
2685 /* If we need to handle SNI or OCSP, do so */
2687 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2688 # ifndef DISABLE_OCSP
2689 if (!(state->verify_stack = sk_X509_new_null()))
2691 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
2696 if (!host) /* server */
2698 # ifndef DISABLE_OCSP
2699 /* We check u_ocsp.server.file, not server.olist, because we care about if
2700 the option exists, not what the current expansion might be, as SNI might
2701 change the certificate and OCSP file in use between now and the time the
2702 callback is invoked. */
2703 if (state->u_ocsp.server.file)
2705 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
2706 SSL_CTX_set_tlsext_status_arg(ctx, state);
2709 /* We always do this, so that $tls_sni is available even if not used in
2711 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
2712 SSL_CTX_set_tlsext_servername_arg(ctx, state);
2714 # ifdef EXIM_HAVE_ALPN
2715 if (tls_alpn && *tls_alpn)
2718 if ( expand_check(tls_alpn, US"tls_alpn", &exp_alpn, errstr)
2719 && *exp_alpn && !isblank(*exp_alpn))
2721 tls_alpn = exp_alpn; /* subprocess so ok to overwrite */
2722 SSL_CTX_set_alpn_select_cb(ctx, tls_server_alpn_cb, state);
2729 # ifndef DISABLE_OCSP
2731 if(ocsp_file) /* wanting stapling */
2733 if (!(state->u_ocsp.client.verify_store = X509_STORE_new()))
2735 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
2738 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
2739 SSL_CTX_set_tlsext_status_arg(ctx, state);
2744 state->verify_cert_hostnames = NULL;
2746 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
2747 /* Set up the RSA callback */
2748 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
2751 /* Finally, set the session cache timeout, and we are done.
2752 The period appears to be also used for (server-generated) session tickets */
2754 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
2755 DEBUG(D_tls) debug_printf("Initialized TLS\n");
2757 *caller_state = state;
2765 /*************************************************
2766 * Get name of cipher in use *
2767 *************************************************/
2770 Argument: pointer to an SSL structure for the connection
2771 pointer to number of bits for cipher
2772 Returns: pointer to allocated string in perm-pool
2776 construct_cipher_name(SSL * ssl, const uschar * ver, int * bits)
2778 int pool = store_pool;
2779 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
2780 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
2781 the accessor functions use const in the prototype. */
2783 const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
2786 SSL_CIPHER_get_bits(c, bits);
2788 store_pool = POOL_PERM;
2789 s = string_sprintf("%s:%s:%u", ver, SSL_CIPHER_get_name(c), *bits);
2791 DEBUG(D_tls) debug_printf("Cipher: %s\n", s);
2796 /* Get IETF-standard name for ciphersuite.
2797 Argument: pointer to an SSL structure for the connection
2798 Returns: pointer to string
2801 static const uschar *
2802 cipher_stdname_ssl(SSL * ssl)
2804 #ifdef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
2805 return CUS SSL_CIPHER_standard_name(SSL_get_current_cipher(ssl));
2807 ushort id = 0xffff & SSL_CIPHER_get_id(SSL_get_current_cipher(ssl));
2808 return cipher_stdname(id >> 8, id & 0xff);
2813 static const uschar *
2814 tlsver_name(SSL * ssl)
2817 int pool = store_pool;
2819 store_pool = POOL_PERM;
2820 s = string_copy(US SSL_get_version(ssl));
2822 if ((p = Ustrchr(s, 'v'))) /* TLSv1.2 -> TLS1.2 */
2823 for (;; p++) if (!(*p = p[1])) break;
2829 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned siz)
2831 /*XXX we might consider a list-of-certs variable for the cert chain.
2832 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
2833 in list-handling functions, also consider the difference between the entire
2834 chain and the elements sent by the peer. */
2836 tlsp->peerdn = NULL;
2838 /* Will have already noted peercert on a verify fail; possibly not the leaf */
2839 if (!tlsp->peercert)
2840 tlsp->peercert = SSL_get_peer_certificate(ssl);
2841 /* Beware anonymous ciphers which lead to server_cert being NULL */
2843 if (!X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, siz))
2844 { DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n"); }
2847 int oldpool = store_pool;
2849 peerdn[siz-1] = '\0'; /* paranoia */
2850 store_pool = POOL_PERM;
2851 tlsp->peerdn = string_copy(peerdn);
2852 store_pool = oldpool;
2854 /* We used to set CV in the cert-verify callbacks (either plain or dane)
2855 but they don't get called on session-resumption. So use the official
2856 interface, which uses the resumed value. Unfortunately this claims verified
2857 when it actually failed but we're in try-verify mode, due to us wanting the
2858 knowlege that it failed so needing to have the callback and forcing a
2859 permissive return. If we don't force it, the TLS startup is failed.
2860 The extra bit of information is set in verify_override in the cb, stashed
2861 for resumption next to the TLS session, and used here. */
2863 if (!tlsp->verify_override)
2864 tlsp->certificate_verified =
2866 tlsp->dane_verified ||
2868 SSL_get_verify_result(ssl) == X509_V_OK;
2876 /*************************************************
2877 * Set up for verifying certificates *
2878 *************************************************/
2880 #ifndef DISABLE_OCSP
2881 /* Load certs from file, return TRUE on success */
2884 chain_from_pem_file(const uschar * file, STACK_OF(X509) ** vp)
2887 STACK_OF(X509) * verify_stack = *vp;
2890 while (sk_X509_num(verify_stack) > 0)
2891 X509_free(sk_X509_pop(verify_stack));
2893 verify_stack = sk_X509_new_null();
2895 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
2896 for (X509 * x; x = PEM_read_bio_X509(bp, NULL, 0, NULL); )
2897 sk_X509_push(verify_stack, x);
2906 /* Called by both client and server startup; on the server possibly
2907 repeated after a Server Name Indication.
2910 sctx SSL_CTX* to initialise
2911 certs certs file, expanded
2912 crl CRL file or NULL
2913 host NULL in a server; the remote host in a client
2914 errstr error string pointer
2916 Returns: OK/DEFER/FAIL
2920 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host,
2923 uschar *expcerts, *expcrl;
2925 if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
2927 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
2929 if (expcerts && *expcerts)
2931 /* Tell the library to use its compiled-in location for the system default
2932 CA bundle. Then add the ones specified in the config, if any. */
2934 if (!SSL_CTX_set_default_verify_paths(sctx))
2935 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
2937 if (Ustrcmp(expcerts, "system") != 0 && Ustrncmp(expcerts, "system,", 7) != 0)
2939 struct stat statbuf;
2941 if (Ustat(expcerts, &statbuf) < 0)
2943 log_write(0, LOG_MAIN|LOG_PANIC,
2944 "failed to stat %s for certificates", expcerts);
2950 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
2951 { file = NULL; dir = expcerts; }
2954 STACK_OF(X509) * verify_stack =
2955 #ifndef DISABLE_OCSP
2956 !host ? state_server.verify_stack :
2959 STACK_OF(X509) ** vp = &verify_stack;
2961 file = expcerts; dir = NULL;
2962 #ifndef DISABLE_OCSP
2963 /* In the server if we will be offering an OCSP proof, load chain from
2964 file for verifying the OCSP proof at load time. */
2966 /*XXX Glitch! The file here is tls_verify_certs: the chain for verifying the client cert.
2967 This is inconsistent with the need to verify the OCSP proof of the server cert.
2970 && statbuf.st_size > 0
2971 && state_server.u_ocsp.server.file
2972 && !chain_from_pem_file(file, vp)
2975 log_write(0, LOG_MAIN|LOG_PANIC,
2976 "failed to load cert chain from %s", file);
2982 /* If a certificate file is empty, the load function fails with an
2983 unhelpful error message. If we skip it, we get the correct behaviour (no
2984 certificates are recognized, but the error message is still misleading (it
2985 says no certificate was supplied). But this is better. */
2987 if ( (!file || statbuf.st_size > 0)
2988 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
2989 return tls_error(US"SSL_CTX_load_verify_locations",
2990 host, NULL, errstr);
2992 /* On the server load the list of CAs for which we will accept certs, for
2993 sending to the client. This is only for the one-file
2994 tls_verify_certificates variant.
2995 If a list isn't loaded into the server, but some verify locations are set,
2996 the server end appears to make a wildcard request for client certs.
2997 Meanwhile, the client library as default behaviour *ignores* the list
2998 we send over the wire - see man SSL_CTX_set_client_cert_cb.
2999 Because of this, and that the dir variant is likely only used for
3000 the public-CA bundle (not for a private CA), not worth fixing. */
3004 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
3005 int i = sk_X509_NAME_num(names);
3007 if (!host) SSL_CTX_set_client_CA_list(sctx, names);
3008 DEBUG(D_tls) debug_printf("Added %d additional certificate authorit%s\n",
3009 i, i>1 ? "ies":"y");
3013 debug_printf("Added dir for additional certificate authorities\n");
3017 /* Handle a certificate revocation list. */
3019 #if OPENSSL_VERSION_NUMBER > 0x00907000L
3021 /* This bit of code is now the version supplied by Lars Mainka. (I have
3022 merely reformatted it into the Exim code style.)
3024 "From here I changed the code to add support for multiple crl's
3025 in pem format in one file or to support hashed directory entries in
3026 pem format instead of a file. This method now uses the library function
3027 X509_STORE_load_locations to add the CRL location to the SSL context.
3028 OpenSSL will then handle the verify against CA certs and CRLs by
3029 itself in the verify callback." */
3031 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
3032 if (expcrl && *expcrl)
3034 struct stat statbufcrl;
3035 if (Ustat(expcrl, &statbufcrl) < 0)
3037 log_write(0, LOG_MAIN|LOG_PANIC,
3038 "failed to stat %s for certificates revocation lists", expcrl);
3043 /* is it a file or directory? */
3045 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
3046 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
3050 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
3056 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
3058 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
3059 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
3061 /* setting the flags to check against the complete crl chain */
3063 X509_STORE_set_flags(cvstore,
3064 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
3068 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
3076 /*************************************************
3077 * Start a TLS session in a server *
3078 *************************************************/
3079 /* This is called when Exim is running as a server, after having received
3080 the STARTTLS command. It must respond to that command, and then negotiate
3084 errstr pointer to error message
3086 Returns: OK on success
3087 DEFER for errors before the start of the negotiation
3088 FAIL for errors during the negotiation; the server can't
3093 tls_server_start(uschar ** errstr)
3096 uschar * expciphers;
3097 exim_openssl_state_st * dummy_statep;
3100 static uschar peerdn[256];
3102 /* Check for previous activation */
3104 if (tls_in.active.sock >= 0)
3106 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
3107 smtp_printf("554 Already in TLS\r\n", FALSE);
3111 /* Initialize the SSL library. If it fails, it will already have logged
3114 rc = tls_init(NULL, NULL,
3115 #ifndef DISABLE_OCSP
3118 NULL, &dummy_statep, &tls_in, errstr);
3119 if (rc != OK) return rc;
3120 ctx = state_server.lib_state.lib_ctx;
3122 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
3123 were historically separated by underscores. So that I can use either form in my
3124 tests, and also for general convenience, we turn underscores into hyphens here.
3126 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
3127 for TLS 1.3 . Since we do not call it at present we get the default list:
3128 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
3131 if (state_server.lib_state.pri_string)
3132 { DEBUG(D_tls) debug_printf("TLS: cipher list was preloaded\n"); }
3135 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
3139 && (rc = server_load_ciphers(ctx, &state_server, expciphers, errstr)) != OK)
3143 /* If this is a host for which certificate verification is mandatory or
3144 optional, set up appropriately. */
3146 tls_in.certificate_verified = FALSE;
3148 tls_in.dane_verified = FALSE;
3150 server_verify_callback_called = FALSE;
3152 if (verify_check_host(&tls_verify_hosts) == OK)
3153 server_verify_optional = FALSE;
3154 else if (verify_check_host(&tls_try_verify_hosts) == OK)
3155 server_verify_optional = TRUE;
3161 if (!expand_check(tls_verify_certificates, US"tls_verify_certificates",
3164 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3166 if (state_server.lib_state.cabundle)
3167 { DEBUG(D_tls) debug_printf("TLS: CA bundle for server was preloaded\n"); }
3169 if ((rc = setup_certs(ctx, expcerts, tls_crl, NULL, errstr)) != OK)
3172 if (expcerts && *expcerts)
3173 setup_cert_verify(ctx, server_verify_optional, verify_callback_server);
3177 #ifndef DISABLE_TLS_RESUME
3178 SSL_CTX_set_tlsext_ticket_key_cb(ctx, ticket_key_callback);
3179 /* despite working, appears to always return failure, so ignoring */
3181 #ifdef OPENSSL_HAVE_NUM_TICKETS
3182 # ifndef DISABLE_TLS_RESUME
3183 SSL_CTX_set_num_tickets(ctx, tls_in.host_resumable ? 1 : 0);
3185 SSL_CTX_set_num_tickets(ctx, 0); /* send no TLS1.3 stateful-tickets */
3190 /* Prepare for new connection */
3192 if (!(ssl = SSL_new(ctx)))
3193 return tls_error(US"SSL_new", NULL, NULL, errstr);
3194 state_server.lib_state.lib_ssl = ssl;
3196 /* Warning: we used to SSL_clear(ssl) here, it was removed.
3198 * With the SSL_clear(), we get strange interoperability bugs with
3199 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
3200 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
3202 * The SSL_clear() call is to let an existing SSL* be reused, typically after
3203 * session shutdown. In this case, we have a brand new object and there's no
3204 * obvious reason to immediately clear it. I'm guessing that this was
3205 * originally added because of incomplete initialisation which the clear fixed,
3206 * in some historic release.
3209 /* Set context and tell client to go ahead, except in the case of TLS startup
3210 on connection, where outputting anything now upsets the clients and tends to
3211 make them disconnect. We need to have an explicit fflush() here, to force out
3212 the response. Other smtp_printf() calls do not need it, because in non-TLS
3213 mode, the fflush() happens when smtp_getc() is called. */
3215 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
3216 if (!tls_in.on_connect)
3218 smtp_printf("220 TLS go ahead\r\n", FALSE);
3222 /* Now negotiate the TLS session. We put our own timer on it, since it seems
3223 that the OpenSSL library doesn't. */
3225 SSL_set_wfd(ssl, fileno(smtp_out));
3226 SSL_set_rfd(ssl, fileno(smtp_in));
3227 SSL_set_accept_state(ssl);
3229 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
3232 sigalrm_seen = FALSE;
3233 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3234 rc = SSL_accept(ssl);
3239 int error = SSL_get_error(ssl, rc);
3242 case SSL_ERROR_NONE:
3245 case SSL_ERROR_ZERO_RETURN:
3246 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3247 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
3249 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
3252 tls_close(NULL, TLS_NO_SHUTDOWN);
3255 /* Handle genuine errors */
3259 int r = ERR_GET_REASON(ERR_peek_error());
3260 if ( r == SSL_R_WRONG_VERSION_NUMBER
3261 #ifdef SSL_R_VERSION_TOO_LOW
3262 || r == SSL_R_VERSION_TOO_LOW
3264 || r == SSL_R_UNKNOWN_PROTOCOL || r == SSL_R_UNSUPPORTED_PROTOCOL)
3265 s = string_sprintf("%s (%s)", s, SSL_get_version(ssl));
3266 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : s, errstr);
3271 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
3272 if (error == SSL_ERROR_SYSCALL)
3276 *errstr = US"SSL_accept: TCP connection closed by peer";
3279 DEBUG(D_tls) debug_printf(" - syscall %s\n", strerror(errno));
3281 (void) tls_error(US"SSL_accept", NULL,
3282 sigalrm_seen ? US"timed out"
3283 : ERR_peek_error() ? NULL : string_sprintf("ret %d", error),
3289 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
3290 ERR_clear_error(); /* Even success can leave errors in the stack. Seen with
3291 anon-authentication ciphersuite negotiated. */
3293 #ifndef DISABLE_TLS_RESUME
3294 if (SSL_session_reused(ssl))
3296 tls_in.resumption |= RESUME_USED;
3297 DEBUG(D_tls) debug_printf("Session reused\n");
3301 #ifdef EXIM_HAVE_ALPN
3302 /* If require-alpn, check server_seen_alpn here. Else abort TLS */
3303 if (!tls_alpn || !*tls_alpn)
3304 { DEBUG(D_tls) debug_printf("TLS: was not watching for ALPN\n"); }
3305 else if (!server_seen_alpn)
3306 if (verify_check_host(&hosts_require_alpn) == OK)
3308 /* We'd like to send a definitive Alert but OpenSSL provides no facility */
3310 tls_error(US"handshake", NULL, US"ALPN required but not negotiated", errstr);
3314 { DEBUG(D_tls) debug_printf("TLS: no ALPN presented in handshake\n"); }
3317 const uschar * name;
3319 SSL_get0_alpn_selected(ssl, &name, &len);
3321 debug_printf("ALPN negotiated: '%.*s'\n", (int)*name, name+1);
3323 debug_printf("ALPN: no protocol negotiated\n");
3328 /* TLS has been set up. Record data for the connection,
3329 adjust the input functions to read via TLS, and initialize things. */
3331 #ifdef SSL_get_extms_support
3332 tls_in.ext_master_secret = SSL_get_extms_support(ssl) == 1;
3334 peer_cert(ssl, &tls_in, peerdn, sizeof(peerdn));
3336 tls_in.ver = tlsver_name(ssl);
3337 tls_in.cipher = construct_cipher_name(ssl, tls_in.ver, &tls_in.bits);
3338 tls_in.cipher_stdname = cipher_stdname_ssl(ssl);
3343 if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)))
3344 debug_printf("Shared ciphers: %s\n", buf);
3346 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3348 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
3349 SSL_SESSION_print_keylog(bp, SSL_get_session(ssl));
3354 #ifdef EXIM_HAVE_SESSION_TICKET
3356 SSL_SESSION * ss = SSL_get_session(ssl);
3357 if (SSL_SESSION_has_ticket(ss)) /* 1.1.0 */
3358 debug_printf("The session has a ticket, life %lu seconds\n",
3359 SSL_SESSION_get_ticket_lifetime_hint(ss));
3364 /* Record the certificate we presented */
3366 X509 * crt = SSL_get_certificate(ssl);
3367 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
3370 /* Channel-binding info for authenticators
3371 See description in https://paquier.xyz/postgresql-2/channel-binding-openssl/ */
3374 size_t len = SSL_get_peer_finished(ssl, &c, 0);
3375 int old_pool = store_pool;
3377 SSL_get_peer_finished(ssl, s = store_get((int)len, FALSE), len);
3378 store_pool = POOL_PERM;
3379 tls_in.channelbinding = b64encode_taint(CUS s, (int)len, FALSE);
3380 store_pool = old_pool;
3381 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage %p\n", tls_in.channelbinding);
3384 /* Only used by the server-side tls (tls_in), including tls_getc.
3385 Client-side (tls_out) reads (seem to?) go via
3386 smtp_read_response()/ip_recv().
3387 Hence no need to duplicate for _in and _out.
3389 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
3390 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
3391 ssl_xfer_eof = ssl_xfer_error = FALSE;
3393 receive_getc = tls_getc;
3394 receive_getbuf = tls_getbuf;
3395 receive_get_cache = tls_get_cache;
3396 receive_hasc = tls_hasc;
3397 receive_ungetc = tls_ungetc;
3398 receive_feof = tls_feof;
3399 receive_ferror = tls_ferror;
3401 tls_in.active.sock = fileno(smtp_out);
3402 tls_in.active.tls_ctx = NULL; /* not using explicit ctx for server-side */
3410 tls_client_basic_ctx_init(SSL_CTX * ctx,
3411 host_item * host, smtp_transport_options_block * ob, exim_openssl_state_st * state,
3416 /* Back-compatible old behaviour if tls_verify_certificates is set but both
3417 tls_verify_hosts and tls_try_verify_hosts are not set. Check only the specified
3418 host patterns if one of them is set with content. */
3420 if ( ( ( !ob->tls_verify_hosts || !ob->tls_verify_hosts
3421 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3423 && ( !ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts
3424 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3427 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
3429 client_verify_optional = FALSE;
3430 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
3431 client_verify_optional = TRUE;
3437 if (!expand_check(ob->tls_verify_certificates, US"tls_verify_certificates",
3440 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3442 if (state->lib_state.cabundle)
3443 { DEBUG(D_tls) debug_printf("TLS: CA bundle was preloaded\n"); }
3445 if ((rc = setup_certs(ctx, expcerts, ob->tls_crl, host, errstr)) != OK)
3448 if (expcerts && *expcerts)
3449 setup_cert_verify(ctx, client_verify_optional, verify_callback_client);
3452 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
3454 state->verify_cert_hostnames =
3456 string_domain_utf8_to_alabel(host->certname, NULL);
3460 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
3461 state->verify_cert_hostnames);
3469 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
3472 const char * hostnames[2] = { CS host->name, NULL };
3475 if (DANESSL_init(ssl, NULL, hostnames) != 1)
3476 return tls_error(US"hostnames load", host, NULL, errstr);
3478 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
3479 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
3480 ) if (rr->type == T_TLSA && rr->size > 3)
3482 const uschar * p = rr->data;
3483 uint8_t usage, selector, mtype;
3484 const char * mdname;
3488 /* Only DANE-TA(2) and DANE-EE(3) are supported */
3489 if (usage != 2 && usage != 3) continue;
3496 default: continue; /* Only match-types 0, 1, 2 are supported */
3497 case 0: mdname = NULL; break;
3498 case 1: mdname = "sha256"; break;
3499 case 2: mdname = "sha512"; break;
3503 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
3506 return tls_error(US"tlsa load", host, NULL, errstr);
3507 case 0: /* action not taken */
3511 tls_out.tlsa_usage |= 1<<usage;
3517 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
3520 #endif /*SUPPORT_DANE*/
3524 #ifndef DISABLE_TLS_RESUME
3525 /* On the client, get any stashed session for the given IP from hints db
3526 and apply it to the ssl-connection for attempted resumption. */
3529 tls_retrieve_session(tls_support * tlsp, SSL * ssl, const uschar * key)
3531 tlsp->resumption |= RESUME_SUPPORTED;
3532 if (tlsp->host_resumable)
3534 dbdata_tls_session * dt;
3536 open_db dbblock, * dbm_file;
3538 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
3539 DEBUG(D_tls) debug_printf("checking for resumable session for %s\n", key);
3540 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3542 /* key for the db is the IP */
3543 if ((dt = dbfn_read_with_length(dbm_file, key, &len)))
3545 SSL_SESSION * ss = NULL;
3546 const uschar * sess_asn1 = dt->session;
3548 len -= sizeof(dbdata_tls_session);
3549 if (!(d2i_SSL_SESSION(&ss, &sess_asn1, (long)len)))
3553 ERR_error_string_n(ERR_get_error(),
3554 ssl_errstring, sizeof(ssl_errstring));
3555 debug_printf("decoding session: %s\n", ssl_errstring);
3560 unsigned long lifetime =
3561 #ifdef EXIM_HAVE_SESSION_TICKET
3562 SSL_SESSION_get_ticket_lifetime_hint(ss);
3563 #else /* Use, fairly arbitrilarily, what we as server would */
3564 f.running_in_test_harness ? 6 : ssl_session_timeout;
3566 if (lifetime + dt->time_stamp < time(NULL))
3568 DEBUG(D_tls) debug_printf("session expired\n");
3569 dbfn_delete(dbm_file, key);
3571 else if (!SSL_set_session(ssl, ss))
3575 ERR_error_string_n(ERR_get_error(),
3576 ssl_errstring, sizeof(ssl_errstring));
3577 debug_printf("applying session to ssl: %s\n", ssl_errstring);
3582 DEBUG(D_tls) debug_printf("good session\n");
3583 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
3584 tlsp->verify_override = dt->verify_override;
3585 tlsp->ocsp = dt->ocsp;
3590 DEBUG(D_tls) debug_printf("no session record\n");
3591 dbfn_close(dbm_file);
3597 /* On the client, save the session for later resumption */
3600 tls_save_session_cb(SSL * ssl, SSL_SESSION * ss)
3602 exim_openssl_state_st * cbinfo = SSL_get_ex_data(ssl, tls_exdata_idx);
3605 DEBUG(D_tls) debug_printf("tls_save_session_cb\n");
3607 if (!cbinfo || !(tlsp = cbinfo->tlsp)->host_resumable) return 0;
3609 # ifdef OPENSSL_HAVE_NUM_TICKETS
3610 if (SSL_SESSION_is_resumable(ss)) /* 1.1.1 */
3613 int len = i2d_SSL_SESSION(ss, NULL);
3614 int dlen = sizeof(dbdata_tls_session) + len;
3615 dbdata_tls_session * dt = store_get(dlen, TRUE);
3616 uschar * s = dt->session;
3617 open_db dbblock, * dbm_file;
3619 DEBUG(D_tls) debug_printf("session is resumable\n");
3620 tlsp->resumption |= RESUME_SERVER_TICKET; /* server gave us a ticket */
3622 dt->verify_override = tlsp->verify_override;
3623 dt->ocsp = tlsp->ocsp;
3624 (void) i2d_SSL_SESSION(ss, &s); /* s gets bumped to end */
3626 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3628 const uschar * key = cbinfo->host->address;
3629 dbfn_delete(dbm_file, key);
3630 dbfn_write(dbm_file, key, dt, dlen);
3631 dbfn_close(dbm_file);
3632 DEBUG(D_tls) debug_printf("wrote session (len %u) to db\n",
3641 tls_client_ctx_resume_prehandshake(
3642 exim_openssl_client_tls_ctx * exim_client_ctx, tls_support * tlsp,
3643 smtp_transport_options_block * ob, host_item * host)
3645 /* Should the client request a session resumption ticket? */
3646 if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
3648 tlsp->host_resumable = TRUE;
3650 SSL_CTX_set_session_cache_mode(exim_client_ctx->ctx,
3651 SSL_SESS_CACHE_CLIENT
3652 | SSL_SESS_CACHE_NO_INTERNAL | SSL_SESS_CACHE_NO_AUTO_CLEAR);
3653 SSL_CTX_sess_set_new_cb(exim_client_ctx->ctx, tls_save_session_cb);
3658 tls_client_ssl_resume_prehandshake(SSL * ssl, tls_support * tlsp,
3659 host_item * host, uschar ** errstr)
3661 if (tlsp->host_resumable)
3664 debug_printf("tls_resumption_hosts overrides openssl_options, enabling tickets\n");
3665 SSL_clear_options(ssl, SSL_OP_NO_TICKET);
3667 tls_exdata_idx = SSL_get_ex_new_index(0, 0, 0, 0, 0);
3668 if (!SSL_set_ex_data(ssl, tls_exdata_idx, client_static_state))
3670 tls_error(US"set ex_data", host, NULL, errstr);
3673 debug_printf("tls_exdata_idx %d cbinfo %p\n", tls_exdata_idx, client_static_state);
3676 tlsp->resumption = RESUME_SUPPORTED;
3677 /* Pick up a previous session, saved on an old ticket */
3678 tls_retrieve_session(tlsp, ssl, host->address);
3683 tls_client_resume_posthandshake(exim_openssl_client_tls_ctx * exim_client_ctx,
3686 if (SSL_session_reused(exim_client_ctx->ssl))
3688 DEBUG(D_tls) debug_printf("The session was reused\n");
3689 tlsp->resumption |= RESUME_USED;
3692 #endif /* !DISABLE_TLS_RESUME */
3695 #ifdef EXIM_HAVE_ALPN
3696 /* Expand and convert an Exim list to an ALPN list. False return for fail.
3697 NULL plist return for silent no-ALPN.
3701 tls_alpn_plist(const uschar * tls_alpn, const uschar ** plist, unsigned * plen,
3706 if (!expand_check(tls_alpn, US"tls_alpn", &exp_alpn, errstr))
3711 DEBUG(D_tls) debug_printf("Setting TLS ALPN forced to fail, not sending\n");
3716 /* The server implementation only accepts exactly one protocol name
3717 but it's little extra code complexity in the client. */
3719 const uschar * list = exp_alpn;
3720 uschar * p = store_get(Ustrlen(exp_alpn), is_tainted(exp_alpn)), * s, * t;
3724 for (t = p; s = string_nextinlist(&list, &sep, NULL, 0); t += len)
3726 *t++ = len = (uschar) Ustrlen(s);
3729 *plist = (*plen = t - p) ? p : NULL;
3733 #endif /* EXIM_HAVE_ALPN */
3736 /*************************************************
3737 * Start a TLS session in a client *
3738 *************************************************/
3740 /* Called from the smtp transport after STARTTLS has been accepted.
3743 cctx connection context
3744 conn_args connection details
3745 cookie datum for randomness; can be NULL
3746 tlsp record details of TLS channel configuration here; must be non-NULL
3747 errstr error string pointer
3749 Returns: TRUE for success with TLS session context set in connection context,
3754 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
3755 void * cookie, tls_support * tlsp, uschar ** errstr)
3757 host_item * host = conn_args->host; /* for msgs and option-tests */
3758 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
3759 smtp_transport_options_block * ob = tb
3760 ? (smtp_transport_options_block *)tb->options_block
3761 : &smtp_transport_option_defaults;
3762 exim_openssl_client_tls_ctx * exim_client_ctx;
3763 uschar * expciphers;
3765 static uschar peerdn[256];
3767 #ifndef DISABLE_OCSP
3768 BOOL request_ocsp = FALSE;
3769 BOOL require_ocsp = FALSE;
3773 store_pool = POOL_PERM;
3774 exim_client_ctx = store_get(sizeof(exim_openssl_client_tls_ctx), FALSE);
3775 exim_client_ctx->corked = NULL;
3779 tlsp->tlsa_usage = 0;
3782 #ifndef DISABLE_OCSP
3784 # ifdef SUPPORT_DANE
3785 /*XXX this should be moved to caller, to be common across gnutls/openssl */
3786 if ( conn_args->dane
3787 && ob->hosts_request_ocsp[0] == '*'
3788 && ob->hosts_request_ocsp[1] == '\0'
3791 /* Unchanged from default. Use a safer one under DANE */
3792 request_ocsp = TRUE;
3793 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
3794 " {= {4}{$tls_out_tlsa_usage}} } "
3800 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK))
3801 request_ocsp = TRUE;
3803 # ifdef SUPPORT_DANE
3807 verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3811 rc = tls_init(host, ob,
3812 #ifndef DISABLE_OCSP
3813 (void *)(long)request_ocsp,
3815 cookie, &client_static_state, tlsp, errstr);
3816 if (rc != OK) return FALSE;
3818 exim_client_ctx->ctx = client_static_state->lib_state.lib_ctx;
3820 tlsp->certificate_verified = FALSE;
3821 client_verify_callback_called = FALSE;
3825 if (conn_args->dane)
3827 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
3828 other failures should be treated as problems. */
3829 if (ob->dane_require_tls_ciphers &&
3830 !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
3831 &expciphers, errstr))
3833 if (expciphers && *expciphers == '\0')
3838 !expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
3839 &expciphers, errstr))
3842 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
3843 are separated by underscores. So that I can use either form in my tests, and
3844 also for general convenience, we turn underscores into hyphens here. */
3848 uschar *s = expciphers;
3849 while (*s) { if (*s == '_') *s = '-'; s++; }
3850 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
3851 if (!SSL_CTX_set_cipher_list(exim_client_ctx->ctx, CS expciphers))
3853 tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
3859 if (conn_args->dane)
3861 SSL_CTX_set_verify(exim_client_ctx->ctx,
3862 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
3863 verify_callback_client_dane);
3865 if (!DANESSL_library_init())
3867 tls_error(US"library init", host, NULL, errstr);
3870 if (DANESSL_CTX_init(exim_client_ctx->ctx) <= 0)
3872 tls_error(US"context init", host, NULL, errstr);
3880 if (tls_client_basic_ctx_init(exim_client_ctx->ctx, host, ob,
3881 client_static_state, errstr) != OK)
3884 #ifndef DISABLE_TLS_RESUME
3885 tls_client_ctx_resume_prehandshake(exim_client_ctx, tlsp, ob, host);
3889 if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx)))
3891 tls_error(US"SSL_new", host, NULL, errstr);
3894 SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx));
3896 SSL_set_fd(exim_client_ctx->ssl, cctx->sock);
3897 SSL_set_connect_state(exim_client_ctx->ssl);
3901 if (!expand_check(ob->tls_sni, US"tls_sni", &tlsp->sni, errstr))
3905 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
3907 else if (!Ustrlen(tlsp->sni))
3911 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
3912 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tlsp->sni);
3913 SSL_set_tlsext_host_name(exim_client_ctx->ssl, tlsp->sni);
3915 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
3922 #ifdef EXIM_HAVE_ALPN
3924 const uschar * plist;
3927 if (!tls_alpn_plist(ob->tls_alpn, &plist, &plen, errstr))
3930 if (SSL_set_alpn_protos(exim_client_ctx->ssl, plist, plen) != 0)
3932 tls_error(US"alpn init", host, NULL, errstr);
3936 DEBUG(D_tls) debug_printf("Setting TLS ALPN '%s'\n", ob->tls_alpn);
3939 log_write(0, LOG_MAIN, "ALPN unusable with this OpenSSL library version; ignoring \"%s\"\n",
3944 if (conn_args->dane)
3945 if (dane_tlsa_load(exim_client_ctx->ssl, host, &conn_args->tlsa_dnsa, errstr) != OK)
3949 #ifndef DISABLE_OCSP
3950 /* Request certificate status at connection-time. If the server
3951 does OCSP stapling we will get the callback (set in tls_init()) */
3952 # ifdef SUPPORT_DANE
3956 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
3957 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
3959 { /* Re-eval now $tls_out_tlsa_usage is populated. If
3960 this means we avoid the OCSP request, we wasted the setup
3961 cost in tls_init(). */
3962 require_ocsp = verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
3963 request_ocsp = require_ocsp
3964 || verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3971 SSL_set_tlsext_status_type(exim_client_ctx->ssl, TLSEXT_STATUSTYPE_ocsp);
3972 client_static_state->u_ocsp.client.verify_required = require_ocsp;
3973 tlsp->ocsp = OCSP_NOT_RESP;
3977 #ifndef DISABLE_TLS_RESUME
3978 if (!tls_client_ssl_resume_prehandshake(exim_client_ctx->ssl, tlsp, host,
3983 #ifndef DISABLE_EVENT
3984 client_static_state->event_action = tb ? tb->event_action : NULL;
3987 /* There doesn't seem to be a built-in timeout on connection. */
3989 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
3990 sigalrm_seen = FALSE;
3991 ALARM(ob->command_timeout);
3992 rc = SSL_connect(exim_client_ctx->ssl);
3996 if (conn_args->dane)
3997 DANESSL_cleanup(exim_client_ctx->ssl);
4002 tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, errstr);
4008 debug_printf("SSL_connect succeeded\n");
4009 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
4011 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
4012 SSL_SESSION_print_keylog(bp, SSL_get_session(exim_client_ctx->ssl));
4018 #ifndef DISABLE_TLS_RESUME
4019 tls_client_resume_posthandshake(exim_client_ctx, tlsp);
4022 #ifdef EXIM_HAVE_ALPN
4023 if (ob->tls_alpn) /* We requested. See what was negotiated. */
4025 const uschar * name;
4028 SSL_get0_alpn_selected(exim_client_ctx->ssl, &name, &len);
4030 { DEBUG(D_tls) debug_printf("ALPN negotiated %u: '%.*s'\n", len, (int)*name, name+1); }
4031 else if (verify_check_given_host(CUSS &ob->hosts_require_alpn, host) == OK)
4033 /* Would like to send a relevant fatal Alert, but OpenSSL has no API */
4034 tls_error(US"handshake", host, US"ALPN required but not negotiated", errstr);
4040 #ifdef SSL_get_extms_support
4041 tlsp->ext_master_secret = SSL_get_extms_support(exim_client_ctx->ssl) == 1;
4043 peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn));
4045 tlsp->ver = tlsver_name(exim_client_ctx->ssl);
4046 tlsp->cipher = construct_cipher_name(exim_client_ctx->ssl, tlsp->ver, &tlsp->bits);
4047 tlsp->cipher_stdname = cipher_stdname_ssl(exim_client_ctx->ssl);
4049 /* Record the certificate we presented */
4051 X509 * crt = SSL_get_certificate(exim_client_ctx->ssl);
4052 tlsp->ourcert = crt ? X509_dup(crt) : NULL;
4055 /*XXX will this work with continued-TLS? */
4056 /* Channel-binding info for authenticators */
4059 size_t len = SSL_get_finished(exim_client_ctx->ssl, &c, 0);
4060 int old_pool = store_pool;
4062 SSL_get_finished(exim_client_ctx->ssl, s = store_get((int)len, TRUE), len);
4063 store_pool = POOL_PERM;
4064 tlsp->channelbinding = b64encode_taint(CUS s, (int)len, TRUE);
4065 store_pool = old_pool;
4066 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage %p %p\n", tlsp->channelbinding, tlsp);
4069 tlsp->active.sock = cctx->sock;
4070 tlsp->active.tls_ctx = exim_client_ctx;
4071 cctx->tls_ctx = exim_client_ctx;
4080 tls_refill(unsigned lim)
4082 SSL * ssl = state_server.lib_state.lib_ssl;
4086 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
4087 ssl_xfer_buffer, ssl_xfer_buffer_size);
4090 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
4091 inbytes = SSL_read(ssl, CS ssl_xfer_buffer,
4092 MIN(ssl_xfer_buffer_size, lim));
4093 error = SSL_get_error(ssl, inbytes);
4094 if (smtp_receive_timeout > 0) ALARM_CLR(0);
4096 if (had_command_timeout) /* set by signal handler */
4097 smtp_command_timeout_exit(); /* does not return */
4098 if (had_command_sigterm)
4099 smtp_command_sigterm_exit();
4100 if (had_data_timeout)
4101 smtp_data_timeout_exit();
4102 if (had_data_sigint)
4103 smtp_data_sigint_exit();
4105 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
4106 closed down, not that the socket itself has been closed down. Revert to
4107 non-SSL handling. */
4111 case SSL_ERROR_NONE:
4114 case SSL_ERROR_ZERO_RETURN:
4115 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
4117 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
4120 tls_close(NULL, TLS_NO_SHUTDOWN);
4123 /* Handle genuine errors */
4125 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4126 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
4127 ssl_xfer_error = TRUE;
4131 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
4132 DEBUG(D_tls) if (error == SSL_ERROR_SYSCALL)
4133 debug_printf(" - syscall %s\n", strerror(errno));
4134 ssl_xfer_error = TRUE;
4138 #ifndef DISABLE_DKIM
4139 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
4141 ssl_xfer_buffer_hwm = inbytes;
4142 ssl_xfer_buffer_lwm = 0;
4147 /*************************************************
4148 * TLS version of getc *
4149 *************************************************/
4151 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
4152 it refills the buffer via the SSL reading function.
4154 Arguments: lim Maximum amount to read/buffer
4155 Returns: the next character or EOF
4157 Only used by the server-side TLS.
4161 tls_getc(unsigned lim)
4163 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
4164 if (!tls_refill(lim))
4165 return ssl_xfer_error ? EOF : smtp_getc(lim);
4167 /* Something in the buffer; return next uschar */
4169 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
4175 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm;
4179 tls_getbuf(unsigned * len)
4184 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
4185 if (!tls_refill(*len))
4187 if (!ssl_xfer_error) return smtp_getbuf(len);
4192 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
4194 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
4195 ssl_xfer_buffer_lwm += size;
4202 tls_get_cache(unsigned lim)
4204 #ifndef DISABLE_DKIM
4205 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
4206 debug_printf("tls_get_cache\n");
4210 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
4216 tls_could_getc(void)
4218 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm
4219 || SSL_pending(state_server.lib_state.lib_ssl) > 0;
4223 /*************************************************
4224 * Read bytes from TLS channel *
4225 *************************************************/
4229 ct_ctx client context pointer, or NULL for the one global server context
4233 Returns: the number of bytes read
4234 -1 after a failed read, including EOF
4236 Only used by the client-side TLS.
4240 tls_read(void * ct_ctx, uschar *buff, size_t len)
4242 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
4243 : state_server.lib_state.lib_ssl;
4247 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
4248 buff, (unsigned int)len);
4251 inbytes = SSL_read(ssl, CS buff, len);
4252 error = SSL_get_error(ssl, inbytes);
4254 if (error == SSL_ERROR_ZERO_RETURN)
4256 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
4259 else if (error != SSL_ERROR_NONE)
4269 /*************************************************
4270 * Write bytes down TLS channel *
4271 *************************************************/
4275 ct_ctx client context pointer, or NULL for the one global server context
4278 more further data expected soon
4280 Returns: the number of bytes after a successful write,
4281 -1 after a failed write
4283 Used by both server-side and client-side TLS. Calling with len zero and more unset
4284 will flush buffered writes; buff can be null for this case.
4288 tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
4291 int outbytes, error;
4293 ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
4294 : state_server.lib_state.lib_ssl;
4295 static gstring * server_corked = NULL;
4296 gstring ** corkedp = ct_ctx
4297 ? &((exim_openssl_client_tls_ctx *)ct_ctx)->corked : &server_corked;
4298 gstring * corked = *corkedp;
4300 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
4301 buff, (unsigned long)len, more ? ", more" : "");
4303 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
4304 "more" is notified. This hack is only ok if small amounts are involved AND only
4305 one stream does it, in one context (i.e. no store reset). Currently it is used
4306 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only.
4307 We support callouts done by the server process by using a separate client
4308 context for the stashed information. */
4309 /* + if PIPE_COMMAND, banner & ehlo-resp for smmtp-on-connect. Suspect there's
4310 a store reset there, so use POOL_PERM. */
4311 /* + if CHUNKING, cmds EHLO,MAIL,RCPT(s),BDAT */
4315 if (!len) buff = US &error; /* dummy just so that string_catn is ok */
4317 int save_pool = store_pool;
4318 store_pool = POOL_PERM;
4320 corked = string_catn(corked, buff, len);
4322 store_pool = save_pool;
4329 buff = CUS corked->s;
4334 for (int left = len; left > 0;)
4336 DEBUG(D_tls) debug_printf("SSL_write(%p, %p, %d)\n", ssl, buff, left);
4338 outbytes = SSL_write(ssl, CS buff, left);
4339 error = SSL_get_error(ssl, outbytes);
4340 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
4343 case SSL_ERROR_NONE: /* the usual case */
4349 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4350 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
4353 case SSL_ERROR_ZERO_RETURN:
4354 log_write(0, LOG_MAIN, "SSL channel closed on write");
4357 case SSL_ERROR_SYSCALL:
4358 if (ct_ctx || errno != ECONNRESET || !f.smtp_in_quit)
4359 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
4360 sender_fullhost ? sender_fullhost : US"<unknown>",
4362 else if (LOGGING(protocol_detail))
4363 log_write(0, LOG_MAIN, "[%s] after QUIT, client reset TCP before"
4364 " SMTP response and TLS close\n", sender_host_address);
4366 DEBUG(D_tls) debug_printf("[%s] SSL_write: after QUIT,"
4367 " client reset TCP before TLS close\n", sender_host_address);
4371 log_write(0, LOG_MAIN, "SSL_write error %d", error);
4382 ct_ctx client TLS context pointer, or NULL for the one global server context
4386 tls_shutdown_wr(void * ct_ctx)
4388 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4389 SSL ** sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4390 int * fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4393 if (*fdp < 0) return; /* TLS was not active */
4395 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
4397 HDEBUG(D_transport|D_tls|D_acl|D_v) debug_printf_indent(" SMTP(TLS shutdown)>>\n");
4398 rc = SSL_shutdown(*sslp);
4399 if (rc < 0) DEBUG(D_tls)
4401 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4402 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4406 /*************************************************
4407 * Close down a TLS session *
4408 *************************************************/
4410 /* This is also called from within a delivery subprocess forked from the
4411 daemon, to shut down the TLS library, without actually doing a shutdown (which
4412 would tamper with the SSL session in the parent process).
4415 ct_ctx client TLS context pointer, or NULL for the one global server context
4416 do_shutdown 0 no data-flush or TLS close-alert
4417 1 if TLS close-alert is to be sent,
4418 2 if also response to be waited for
4422 Used by both server-side and client-side TLS.
4426 tls_close(void * ct_ctx, int do_shutdown)
4428 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4429 SSL ** sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4430 int * fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4432 if (*fdp < 0) return; /* TLS was not active */
4437 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
4438 do_shutdown > 1 ? " (with response-wait)" : "");
4440 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
4442 if ( (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
4446 rc = SSL_shutdown(*sslp); /* wait for response */
4450 if (rc < 0) DEBUG(D_tls)
4452 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4453 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4457 if (!o_ctx) /* server side */
4459 #ifndef DISABLE_OCSP
4460 sk_X509_pop_free(state_server.verify_stack, X509_free);
4461 state_server.verify_stack = NULL;
4464 receive_getc = smtp_getc;
4465 receive_getbuf = smtp_getbuf;
4466 receive_get_cache = smtp_get_cache;
4467 receive_hasc = smtp_hasc;
4468 receive_ungetc = smtp_ungetc;
4469 receive_feof = smtp_feof;
4470 receive_ferror = smtp_ferror;
4471 tls_in.active.tls_ctx = NULL;
4473 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
4484 /*************************************************
4485 * Let tls_require_ciphers be checked at startup *
4486 *************************************************/
4488 /* The tls_require_ciphers option, if set, must be something which the
4491 Returns: NULL on success, or error message
4495 tls_validate_require_cipher(void)
4498 uschar *s, *expciphers, *err;
4502 if (!(tls_require_ciphers && *tls_require_ciphers))
4505 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
4507 return US"failed to expand tls_require_ciphers";
4509 if (!(expciphers && *expciphers))
4512 /* normalisation ripped from above */
4514 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
4518 if (lib_ctx_new(&ctx, NULL, &err) == OK)
4521 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
4523 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
4525 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4526 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
4527 expciphers, ssl_errstring);
4538 /*************************************************
4539 * Report the library versions. *
4540 *************************************************/
4542 /* There have historically been some issues with binary compatibility in
4543 OpenSSL libraries; if Exim (like many other applications) is built against
4544 one version of OpenSSL but the run-time linker picks up another version,
4545 it can result in serious failures, including crashing with a SIGSEGV. So
4546 report the version found by the compiler and the run-time version.
4548 Note: some OS vendors backport security fixes without changing the version
4549 number/string, and the version date remains unchanged. The _build_ date
4550 will change, so we can more usefully assist with version diagnosis by also
4551 reporting the build date.
4553 Arguments: a FILE* to print the results to
4558 tls_version_report(FILE *f)
4560 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
4563 OPENSSL_VERSION_TEXT,
4564 SSLeay_version(SSLEAY_VERSION),
4565 SSLeay_version(SSLEAY_BUILT_ON));
4566 /* third line is 38 characters for the %s and the line is 73 chars long;
4567 the OpenSSL output includes a "built on: " prefix already. */
4573 /*************************************************
4574 * Random number generation *
4575 *************************************************/
4577 /* Pseudo-random number generation. The result is not expected to be
4578 cryptographically strong but not so weak that someone will shoot themselves
4579 in the foot using it as a nonce in input in some email header scheme or
4580 whatever weirdness they'll twist this into. The result should handle fork()
4581 and avoid repeating sequences. OpenSSL handles that for us.
4585 Returns a random number in range [0, max-1]
4589 vaguely_random_number(int max)
4593 static pid_t pidlast = 0;
4595 uschar smallbuf[sizeof(r)];
4601 if (pidnow != pidlast)
4603 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
4604 is unique for each thread", this doesn't apparently apply across processes,
4605 so our own warning from vaguely_random_number_fallback() applies here too.
4606 Fix per PostgreSQL. */
4612 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
4616 gettimeofday(&r.tv, NULL);
4619 RAND_seed(US (&r), sizeof(r));
4621 /* We're after pseudo-random, not random; if we still don't have enough data
4622 in the internal PRNG then our options are limited. We could sleep and hope
4623 for entropy to come along (prayer technique) but if the system is so depleted
4624 in the first place then something is likely to just keep taking it. Instead,
4625 we'll just take whatever little bit of pseudo-random we can still manage to
4628 needed_len = sizeof(r);
4629 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
4630 asked for a number less than 10. */
4631 for (r = max, i = 0; r; ++i)
4637 #ifdef EXIM_HAVE_RAND_PSEUDO
4638 /* We do not care if crypto-strong */
4639 i = RAND_pseudo_bytes(smallbuf, needed_len);
4641 i = RAND_bytes(smallbuf, needed_len);
4647 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
4648 return vaguely_random_number_fallback(max);
4652 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
4655 /* We don't particularly care about weighted results; if someone wants
4656 smooth distribution and cares enough then they should submit a patch then. */
4663 /*************************************************
4664 * OpenSSL option parse *
4665 *************************************************/
4667 /* Parse one option for tls_openssl_options_parse below
4670 name one option name
4671 value place to store a value for it
4672 Returns success or failure in parsing
4678 tls_openssl_one_option_parse(uschar *name, long *value)
4681 int last = exim_openssl_options_size;
4682 while (last > first)
4684 int middle = (first + last)/2;
4685 int c = Ustrcmp(name, exim_openssl_options[middle].name);
4688 *value = exim_openssl_options[middle].value;
4702 /*************************************************
4703 * OpenSSL option parsing logic *
4704 *************************************************/
4706 /* OpenSSL has a number of compatibility options which an administrator might
4707 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
4708 we look like log_selector.
4711 option_spec the administrator-supplied string of options
4712 results ptr to long storage for the options bitmap
4713 Returns success or failure
4717 tls_openssl_options_parse(uschar *option_spec, long *results)
4720 uschar * exp, * end;
4721 BOOL adding, item_parsed;
4723 /* Server: send no (<= TLS1.2) session tickets */
4724 result = SSL_OP_NO_TICKET;
4726 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
4727 from default because it increases BEAST susceptibility. */
4728 #ifdef SSL_OP_NO_SSLv2
4729 result |= SSL_OP_NO_SSLv2;
4731 #ifdef SSL_OP_NO_SSLv3
4732 result |= SSL_OP_NO_SSLv3;
4734 #ifdef SSL_OP_SINGLE_DH_USE
4735 result |= SSL_OP_SINGLE_DH_USE;
4737 #ifdef SSL_OP_NO_RENEGOTIATION
4738 result |= SSL_OP_NO_RENEGOTIATION;
4747 if (!expand_check(option_spec, US"openssl_options", &exp, &end))
4750 for (uschar * s = exp; *s; /**/)
4752 while (isspace(*s)) ++s;
4755 if (*s != '+' && *s != '-')
4757 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
4758 "+ or - expected but found \"%s\"\n", s);
4761 adding = *s++ == '+';
4762 for (end = s; *end && !isspace(*end); ) end++;
4763 item_parsed = tls_openssl_one_option_parse(string_copyn(s, end-s), &item);
4766 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
4769 DEBUG(D_tls) debug_printf("openssl option, %s %08lx: %08lx (%s)\n",
4770 adding ? "adding to " : "removing from", result, item, s);
4782 #endif /*!MACRO_PREDEF*/
4785 /* End of tls-openssl.c */