1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) The Exim Maintainers 2020 - 2022 */
6 /* Copyright (c) University of Cambridge 1995 - 2019 */
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) && (OPENSSL_VERSION_NUMBER >= 0x030000000L)
98 # define EXIM_HAVE_EXPORT_CHNL_BNGNG
101 #if !defined(LIBRESSL_VERSION_NUMBER) \
102 || LIBRESSL_VERSION_NUMBER >= 0x20010000L
103 # if !defined(OPENSSL_NO_ECDH)
104 # if OPENSSL_VERSION_NUMBER >= 0x0090800fL
105 # define EXIM_HAVE_ECDH
107 # if OPENSSL_VERSION_NUMBER >= 0x10002000L
108 # define EXIM_HAVE_OPENSSL_EC_NIST2NID
113 #ifndef LIBRESSL_VERSION_NUMBER
114 # if OPENSSL_VERSION_NUMBER >= 0x010101000L
115 # define OPENSSL_HAVE_KEYLOG_CB
116 # define OPENSSL_HAVE_NUM_TICKETS
117 # define EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
118 # define EXIM_HAVE_EXP_CHNL_BNGNG
120 # define OPENSSL_BAD_SRVR_OURCERT
124 #if !defined(LIBRESSL_VERSION_NUMBER) && (OPENSSL_VERSION_NUMBER >= 0x010002000L)
125 # define EXIM_HAVE_EXPORT_CHNL_BNGNG
128 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
129 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
130 # define DISABLE_OCSP
133 #ifndef DISABLE_TLS_RESUME
134 # if OPENSSL_VERSION_NUMBER < 0x0101010L
135 # error OpenSSL version too old for session-resumption
139 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
140 # include <openssl/x509v3.h>
143 #ifndef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
144 # ifndef EXIM_HAVE_OPENSSL_CIPHER_GET_ID
145 # define SSL_CIPHER_get_id(c) (c->id)
147 # ifndef MACRO_PREDEF
148 # include "tls-cipher-stdname.c"
152 /*************************************************
153 * OpenSSL option parse *
154 *************************************************/
156 typedef struct exim_openssl_option {
159 } exim_openssl_option;
160 /* We could use a macro to expand, but we need the ifdef and not all the
161 options document which version they were introduced in. Policylet: include
162 all options unless explicitly for DTLS, let the administrator choose which
165 This list is current as of:
168 XXX could we autobuild this list, as with predefined-macros?
169 Seems just parsing ssl.h for SSL_OP_.* would be enough (except to exclude DTLS).
170 Also allow a numeric literal?
172 static exim_openssl_option exim_openssl_options[] = {
173 /* KEEP SORTED ALPHABETICALLY! */
175 { US"all", (long) SSL_OP_ALL },
177 #ifdef SSL_OP_ALLOW_NO_DHE_KEX
178 { US"allow_no_dhe_kex", SSL_OP_ALLOW_NO_DHE_KEX },
180 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
181 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
183 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
184 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
186 #ifdef SSL_OP_CRYPTOPRO_TLSEXT_BUG
187 { US"cryptopro_tlsext_bug", SSL_OP_CRYPTOPRO_TLSEXT_BUG },
189 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
190 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
192 #ifdef SSL_OP_ENABLE_MIDDLEBOX_COMPAT
193 { US"enable_middlebox_compat", SSL_OP_ENABLE_MIDDLEBOX_COMPAT },
195 #ifdef SSL_OP_EPHEMERAL_RSA
196 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
198 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
199 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
201 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
202 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
204 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
205 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
207 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
208 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
210 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
211 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
213 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
214 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
216 #ifdef SSL_OP_NO_ANTI_REPLAY
217 { US"no_anti_replay", SSL_OP_NO_ANTI_REPLAY },
219 #ifdef SSL_OP_NO_COMPRESSION
220 { US"no_compression", SSL_OP_NO_COMPRESSION },
222 #ifdef SSL_OP_NO_ENCRYPT_THEN_MAC
223 { US"no_encrypt_then_mac", SSL_OP_NO_ENCRYPT_THEN_MAC },
225 #ifdef SSL_OP_NO_RENEGOTIATION
226 { US"no_renegotiation", SSL_OP_NO_RENEGOTIATION },
228 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
229 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
231 #ifdef SSL_OP_NO_SSLv2
232 { US"no_sslv2", SSL_OP_NO_SSLv2 },
234 #ifdef SSL_OP_NO_SSLv3
235 { US"no_sslv3", SSL_OP_NO_SSLv3 },
237 #ifdef SSL_OP_NO_TICKET
238 { US"no_ticket", SSL_OP_NO_TICKET },
240 #ifdef SSL_OP_NO_TLSv1
241 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
243 #ifdef SSL_OP_NO_TLSv1_1
244 # if OPENSSL_VERSION_NUMBER < 0x30000000L
245 # if SSL_OP_NO_TLSv1_1 == 0x00000400L
246 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
247 # warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
248 # define NO_SSL_OP_NO_TLSv1_1
251 # ifndef NO_SSL_OP_NO_TLSv1_1
252 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
255 #ifdef SSL_OP_NO_TLSv1_2
256 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
258 #ifdef SSL_OP_NO_TLSv1_3
259 { US"no_tlsv1_3", SSL_OP_NO_TLSv1_3 },
261 #ifdef SSL_OP_PRIORITIZE_CHACHA
262 { US"prioritize_chacha", SSL_OP_PRIORITIZE_CHACHA },
264 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
265 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
267 #ifdef SSL_OP_SINGLE_DH_USE
268 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
270 #ifdef SSL_OP_SINGLE_ECDH_USE
271 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
273 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
274 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
276 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
277 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
279 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
280 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
282 #ifdef SSL_OP_TLS_D5_BUG
283 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
285 #ifdef SSL_OP_TLS_ROLLBACK_BUG
286 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
288 #ifdef SSL_OP_TLSEXT_PADDING
289 { US"tlsext_padding", SSL_OP_TLSEXT_PADDING },
294 static int exim_openssl_options_size = nelem(exim_openssl_options);
295 static long init_options = 0;
304 for (struct exim_openssl_option * o = exim_openssl_options;
305 o < exim_openssl_options + nelem(exim_openssl_options); o++)
307 /* Trailing X is workaround for problem with _OPT_OPENSSL_NO_TLSV1
308 being a ".ifdef _OPT_OPENSSL_NO_TLSV1_3" match */
310 spf(buf, sizeof(buf), US"_OPT_OPENSSL_%T_X", o->name);
311 builtin_macro_create(buf);
314 # ifndef DISABLE_TLS_RESUME
315 builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING );
317 # ifdef SSL_OP_NO_TLSv1_3
318 builtin_macro_create(US"_HAVE_TLS1_3");
320 # ifdef OPENSSL_BAD_SRVR_OURCERT
321 builtin_macro_create(US"_TLS_BAD_MULTICERT_IN_OURCERT");
323 # ifdef EXIM_HAVE_OCSP
324 builtin_macro_create(US"_HAVE_TLS_OCSP");
325 builtin_macro_create(US"_HAVE_TLS_OCSP_LIST");
327 # ifdef EXIM_HAVE_ALPN
328 builtin_macro_create(US"_HAVE_TLS_ALPN");
333 /******************************************************************************/
335 /* Structure for collecting random data for seeding. */
337 typedef struct randstuff {
342 /* Local static variables */
344 static BOOL client_verify_callback_called = FALSE;
345 static BOOL server_verify_callback_called = FALSE;
346 static const uschar *sid_ctx = US"exim";
348 /* We have three different contexts to care about.
350 Simple case: client, `client_ctx`
351 As a client, we can be doing a callout or cut-through delivery while receiving
352 a message. So we have a client context, which should have options initialised
353 from the SMTP Transport. We may also concurrently want to make TLS connections
354 to utility daemons, so client-contexts are allocated and passed around in call
355 args rather than using a gobal.
358 There are two cases: with and without ServerNameIndication from the client.
359 Given TLS SNI, we can be using different keys, certs and various other
360 configuration settings, because they're re-expanded with $tls_sni set. This
361 allows vhosting with TLS. This SNI is sent in the handshake.
362 A client might not send SNI, so we need a fallback, and an initial setup too.
363 So as a server, we start out using `server_ctx`.
364 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
365 `server_sni` from `server_ctx` and then initialise settings by re-expanding
373 } exim_openssl_client_tls_ctx;
376 /* static SSL_CTX *server_ctx = NULL; */
377 /* static SSL *server_ssl = NULL; */
379 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
380 static SSL_CTX *server_sni = NULL;
382 #ifdef EXIM_HAVE_ALPN
383 static BOOL server_seen_alpn = FALSE;
386 static char ssl_errstring[256];
388 static int ssl_session_timeout = 7200; /* Two hours */
389 static BOOL client_verify_optional = FALSE;
390 static BOOL server_verify_optional = FALSE;
392 static BOOL reexpand_tls_files_for_sni = FALSE;
395 typedef struct ocsp_resp {
396 struct ocsp_resp * next;
397 OCSP_RESPONSE * resp;
400 typedef struct exim_openssl_state {
401 exim_tlslib_state lib_state;
402 #define lib_ctx libdata0
403 #define lib_ssl libdata1
406 uschar * certificate;
410 STACK_OF(X509) *verify_stack; /* chain for verifying the proof */
414 const uschar *file_expanded;
415 ocsp_resplist *olist;
418 X509_STORE *verify_store; /* non-null if status requested */
419 BOOL verify_required;
424 /* these are cached from first expand */
425 uschar * server_cipher_list;
426 /* only passed down to tls_error: */
428 const uschar * verify_cert_hostnames;
429 #ifndef DISABLE_EVENT
430 uschar * event_action;
432 } exim_openssl_state_st;
434 /* should figure out a cleanup of API to handle state preserved per
435 implementation, for various reasons, which can be void * in the APIs.
436 For now, we hack around it. */
437 exim_openssl_state_st *client_static_state = NULL; /*XXX should not use static; multiple concurrent clients! */
438 exim_openssl_state_st state_server = {.is_server = TRUE};
441 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host,
446 static int tls_server_stapling_cb(SSL *s, void *arg);
451 /* Daemon-called, before every connection, key create/rotate */
452 #ifndef DISABLE_TLS_RESUME
453 static void tk_init(void);
454 static int tls_exdata_idx = -1;
458 tls_per_lib_daemon_tick(void)
460 #ifndef DISABLE_TLS_RESUME
465 /* Called once at daemon startup */
468 tls_per_lib_daemon_init(void)
470 tls_daemon_creds_reload();
474 /*************************************************
476 *************************************************/
478 /* Called from lots of places when errors occur before actually starting to do
479 the TLS handshake, that is, while the session is still in clear. Always returns
480 DEFER for a server and FAIL for a client so that most calls can use "return
481 tls_error(...)" to do this processing and then give an appropriate return. A
482 single function is used for both server and client, because it is called from
483 some shared functions.
486 prefix text to include in the logged error
487 host NULL if setting up a server;
488 the connected host if setting up a client
489 msg error message or NULL if we should ask OpenSSL
490 errstr pointer to output error message
492 Returns: OK/DEFER/FAIL
496 tls_error(uschar * prefix, const host_item * host, uschar * msg, uschar ** errstr)
500 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
501 msg = US ssl_errstring;
504 msg = string_sprintf("(%s): %s", prefix, msg);
505 DEBUG(D_tls) debug_printf("TLS error '%s'\n", msg);
506 if (errstr) *errstr = msg;
507 return host ? FAIL : DEFER;
512 /**************************************************
513 * General library initalisation *
514 **************************************************/
517 lib_rand_init(void * addr)
520 if (!RAND_status()) return TRUE;
522 gettimeofday(&r.tv, NULL);
524 RAND_seed(US (&r), sizeof(r));
525 RAND_seed(US big_buffer, big_buffer_size);
526 if (addr) RAND_seed(US addr, sizeof(addr));
528 return RAND_status();
533 tls_openssl_init(void)
535 static BOOL once = FALSE;
539 #ifdef EXIM_NEED_OPENSSL_INIT
540 SSL_load_error_strings(); /* basic set up */
541 OpenSSL_add_ssl_algorithms();
544 #if defined(EXIM_HAVE_SHA256) && !defined(OPENSSL_AUTO_SHA256)
545 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
546 list of available digests. */
547 EVP_add_digest(EVP_sha256());
550 (void) lib_rand_init(NULL);
551 (void) tls_openssl_options_parse(openssl_options, &init_options);
556 /*************************************************
557 * Initialize for DH *
558 *************************************************/
560 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
564 sctx The current SSL CTX (inbound or outbound)
565 dhparam DH parameter file or fixed parameter identity string
566 errstr error string pointer
568 Returns: TRUE if OK (nothing to set up, or setup worked)
572 init_dh(SSL_CTX * sctx, uschar * dhparam, uschar ** errstr)
575 #if OPENSSL_VERSION_NUMBER < 0x30000000L
584 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded, errstr))
587 if (!dhexpanded || !*dhexpanded)
588 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
589 else if (dhexpanded[0] == '/')
591 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
593 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
594 NULL, US strerror(errno), errstr);
600 if (Ustrcmp(dhexpanded, "none") == 0)
602 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
606 if (!(pem = std_dh_prime_named(dhexpanded)))
608 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
609 NULL, US strerror(errno), errstr);
612 bio = BIO_new_mem_buf(CS pem, -1);
616 #if OPENSSL_VERSION_NUMBER < 0x30000000L
617 dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)
619 pkey = PEM_read_bio_Parameters_ex(bio, NULL, NULL, NULL)
624 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
629 /* note: our default limit of 2236 is not a multiple of 8; the limit comes from
630 an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with 2236.
631 But older OpenSSL can only report in bytes (octets), not bits. If someone wants
632 to dance at the edge, then they can raise the limit or use current libraries. */
634 #if OPENSSL_VERSION_NUMBER < 0x30000000L
635 # ifdef EXIM_HAVE_OPENSSL_DH_BITS
636 /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022
637 This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */
638 dh_bitsize = DH_bits(dh);
640 dh_bitsize = 8 * DH_size(dh);
643 dh_bitsize = EVP_PKEY_get_bits(pkey);
646 /* Even if it is larger, we silently return success rather than cause things to
647 fail out, so that a too-large DH will not knock out all TLS; it's a debatable
648 choice. Likewise for a failing attempt to set one. */
650 if (dh_bitsize <= tls_dh_max_bits)
653 #if OPENSSL_VERSION_NUMBER < 0x30000000L
654 SSL_CTX_set_tmp_dh(sctx, dh)
656 SSL_CTX_set0_tmp_dh_pkey(sctx, pkey)
660 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
661 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (D-H param setting '%s'): %s",
662 dhexpanded ? dhexpanded : US"default", ssl_errstring);
663 #if OPENSSL_VERSION_NUMBER >= 0x30000000L
664 /* EVP_PKEY_free(pkey); crashes */
669 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
670 dhexpanded ? dhexpanded : US"default", dh_bitsize);
674 debug_printf("dhparams '%s' %d bits, is > tls_dh_max_bits limit of %d\n",
675 dhexpanded ? dhexpanded : US"default", dh_bitsize, tls_dh_max_bits);
677 #if OPENSSL_VERSION_NUMBER < 0x30000000L
680 /* The EVP_PKEY ownership stays with the ctx; do not free it */
689 /*************************************************
690 * Initialize for ECDH *
691 *************************************************/
693 /* Load parameters for ECDH encryption. Server only.
695 For now, we stick to NIST P-256 because: it's simple and easy to configure;
696 it avoids any patent issues that might bite redistributors; despite events in
697 the news and concerns over curve choices, we're not cryptographers, we're not
698 pretending to be, and this is "good enough" to be better than no support,
699 protecting against most adversaries. Given another year or two, there might
700 be sufficient clarity about a "right" way forward to let us make an informed
701 decision, instead of a knee-jerk reaction.
703 Longer-term, we should look at supporting both various named curves and
704 external files generated with "openssl ecparam", much as we do for init_dh().
705 We should also support "none" as a value, to explicitly avoid initialisation.
710 sctx The current SSL CTX (inbound or outbound)
711 errstr error string pointer
713 Returns: TRUE if OK (nothing to set up, or setup worked)
717 init_ecdh(SSL_CTX * sctx, uschar ** errstr)
719 #ifdef OPENSSL_NO_ECDH
727 # ifndef EXIM_HAVE_ECDH
729 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
733 if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve, errstr))
735 if (!exp_curve || !*exp_curve)
738 /* "auto" needs to be handled carefully.
739 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
740 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
741 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
742 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
743 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
745 if (Ustrcmp(exp_curve, "auto") == 0)
747 #if OPENSSL_VERSION_NUMBER < 0x10002000L
748 DEBUG(D_tls) debug_printf(
749 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
750 exp_curve = US"prime256v1";
752 # if defined SSL_CTRL_SET_ECDH_AUTO
753 DEBUG(D_tls) debug_printf(
754 "ECDH OpenSSL 1.0.2+: temp key parameter settings: autoselection\n");
755 SSL_CTX_set_ecdh_auto(sctx, 1);
758 DEBUG(D_tls) debug_printf(
759 "ECDH OpenSSL 1.1.0+: temp key parameter settings: default selection\n");
765 DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve);
766 if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef
767 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
768 && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef
772 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve),
777 # if OPENSSL_VERSION_NUMBER < 0x30000000L
780 if (!(ecdh = EC_KEY_new_by_curve_name(nid)))
782 tls_error(US"Unable to create ec curve", NULL, NULL, errstr);
786 /* The "tmp" in the name here refers to setting a temporary key
787 not to the stability of the interface. */
789 if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0))
790 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), NULL, NULL, errstr);
792 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve);
796 #else /* v 3.0.0 + */
798 if ((rv = SSL_CTX_set1_groups(sctx, &nid, 1)) == 0)
799 tls_error(string_sprintf("Error enabling '%s' group", exp_curve), NULL, NULL, errstr);
801 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' group\n", exp_curve);
807 # endif /*EXIM_HAVE_ECDH*/
808 #endif /*OPENSSL_NO_ECDH*/
813 /*************************************************
814 * Expand key and cert file specs *
815 *************************************************/
817 #if OPENSSL_VERSION_NUMBER < 0x30000000L
820 s SSL connection (not used)
824 Returns: pointer to generated key
828 rsa_callback(SSL *s, int export, int keylength)
831 #ifdef EXIM_HAVE_RSA_GENKEY_EX
832 BIGNUM *bn = BN_new();
835 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
837 # ifdef EXIM_HAVE_RSA_GENKEY_EX
838 if ( !BN_set_word(bn, (unsigned long)RSA_F4)
839 || !(rsa_key = RSA_new())
840 || !RSA_generate_key_ex(rsa_key, keylength, bn, NULL)
843 if (!(rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL)))
847 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
848 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
854 #endif /* pre-3.0.0 */
858 /* Create and install a selfsigned certificate, for use in server mode */
859 /*XXX we could arrange to call this during prelo for a null tls_certificate option.
860 The normal cache inval + relo will suffice.
861 Just need a timer for inval. */
864 tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr)
871 DEBUG(D_tls) debug_printf("TLS: generating selfsigned server cert\n");
872 where = US"allocating pkey";
873 if (!(pkey = EVP_PKEY_new()))
876 where = US"allocating cert";
877 if (!(x509 = X509_new()))
880 where = US"generating pkey";
881 #if OPENSSL_VERSION_NUMBER < 0x30000000L
884 if (!(rsa = rsa_callback(NULL, 0, 2048)))
887 where = US"assigning pkey";
888 if (!EVP_PKEY_assign_RSA(pkey, rsa))
892 pkey = EVP_RSA_gen(2048);
895 X509_set_version(x509, 2); /* N+1 - version 3 */
896 ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
897 X509_gmtime_adj(X509_get_notBefore(x509), 0);
898 X509_gmtime_adj(X509_get_notAfter(x509), (long)2 * 60 * 60); /* 2 hour */
899 X509_set_pubkey(x509, pkey);
901 name = X509_get_subject_name(x509);
902 X509_NAME_add_entry_by_txt(name, "C",
903 MBSTRING_ASC, CUS "UK", -1, -1, 0);
904 X509_NAME_add_entry_by_txt(name, "O",
905 MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0);
906 X509_NAME_add_entry_by_txt(name, "CN",
907 MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0);
908 X509_set_issuer_name(x509, name);
910 where = US"signing cert";
911 if (!X509_sign(x509, pkey, EVP_md5()))
914 where = US"installing selfsign cert";
915 if (!SSL_CTX_use_certificate(sctx, x509))
918 where = US"installing selfsign key";
919 if (!SSL_CTX_use_PrivateKey(sctx, pkey))
925 (void) tls_error(where, NULL, NULL, errstr);
926 if (x509) X509_free(x509);
927 if (pkey) EVP_PKEY_free(pkey);
937 /*************************************************
938 * Information callback *
939 *************************************************/
941 /* The SSL library functions call this from time to time to indicate what they
942 are doing. We copy the string to the debugging output when TLS debugging has
954 info_callback(SSL * s, int where, int ret)
960 if (where & SSL_ST_CONNECT) g = string_append_listele(g, ',', US"SSL_connect");
961 if (where & SSL_ST_ACCEPT) g = string_append_listele(g, ',', US"SSL_accept");
962 if (where & SSL_CB_LOOP) g = string_append_listele(g, ',', US"state_chg");
963 if (where & SSL_CB_EXIT) g = string_append_listele(g, ',', US"hshake_exit");
964 if (where & SSL_CB_READ) g = string_append_listele(g, ',', US"read");
965 if (where & SSL_CB_WRITE) g = string_append_listele(g, ',', US"write");
966 if (where & SSL_CB_ALERT) g = string_append_listele(g, ',', US"alert");
967 if (where & SSL_CB_HANDSHAKE_START) g = string_append_listele(g, ',', US"hshake_start");
968 if (where & SSL_CB_HANDSHAKE_DONE) g = string_append_listele(g, ',', US"hshake_done");
970 if (where & SSL_CB_LOOP)
971 debug_printf("SSL %s: %s\n", g->s, SSL_state_string_long(s));
972 else if (where & SSL_CB_ALERT)
973 debug_printf("SSL %s %s:%s\n", g->s,
974 SSL_alert_type_string_long(ret), SSL_alert_desc_string_long(ret));
975 else if (where & SSL_CB_EXIT)
978 debug_printf("SSL %s: %s in %s\n", g->s,
979 ret == 0 ? "failed" : "error", SSL_state_string_long(s));
981 else if (where & (SSL_CB_HANDSHAKE_START | SSL_CB_HANDSHAKE_DONE))
982 debug_printf("SSL %s: %s\n", g->s, SSL_state_string_long(s));
986 #ifdef OPENSSL_HAVE_KEYLOG_CB
988 keylog_callback(const SSL *ssl, const char *line)
992 DEBUG(D_tls) debug_printf("%.200s\n", line);
993 if (!(filename = getenv("SSLKEYLOGFILE"))) return;
994 if (!(fp = fopen(filename, "a"))) return;
995 fprintf(fp, "%s\n", line);
1004 #ifndef DISABLE_EVENT
1006 verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
1007 BOOL *calledp, const BOOL *optionalp, const uschar * what)
1013 ev = tlsp == &tls_out ? client_static_state->event_action : event_action;
1016 DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth);
1017 old_cert = tlsp->peercert;
1018 tlsp->peercert = X509_dup(cert);
1019 /* NB we do not bother setting peerdn */
1020 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth), &errno)))
1022 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
1023 "depth=%d cert=%s: %s",
1024 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1025 what, depth, dn, yield);
1029 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
1030 return 1; /* reject (leaving peercert set) */
1032 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
1033 "(host in tls_try_verify_hosts)\n");
1034 tlsp->verify_override = TRUE;
1036 X509_free(tlsp->peercert);
1037 tlsp->peercert = old_cert;
1043 /*************************************************
1044 * Callback for verification *
1045 *************************************************/
1047 /* The SSL library does certificate verification if set up to do so. This
1048 callback has the current yes/no state is in "state". If verification succeeded,
1049 we set the certificate-verified flag. If verification failed, what happens
1050 depends on whether the client is required to present a verifiable certificate
1053 If verification is optional, we change the state to yes, but still log the
1054 verification error. For some reason (it really would help to have proper
1055 documentation of OpenSSL), this callback function then gets called again, this
1056 time with state = 1. We must take care not to set the private verified flag on
1057 the second time through.
1059 Note: this function is not called if the client fails to present a certificate
1060 when asked. We get here only if a certificate has been received. Handling of
1061 optional verification for this case is done when requesting SSL to verify, by
1062 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
1064 May be called multiple times for different issues with a certificate, even
1065 for a given "depth" in the certificate chain.
1068 preverify_ok current yes/no state as 1/0
1069 x509ctx certificate information.
1070 tlsp per-direction (client vs. server) support data
1071 calledp has-been-called flag
1072 optionalp verification-is-optional flag
1074 Returns: 0 if verification should fail, otherwise 1
1078 verify_callback(int preverify_ok, X509_STORE_CTX * x509ctx,
1079 tls_support * tlsp, BOOL * calledp, BOOL * optionalp)
1081 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
1082 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
1085 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
1087 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
1088 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1089 tlsp == &tls_out ? deliver_host_address : sender_host_address);
1092 dn[sizeof(dn)-1] = '\0';
1094 tlsp->verify_override = FALSE;
1095 if (preverify_ok == 0)
1097 uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])",
1098 *verify_mode, sender_host_address)
1100 log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
1101 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1103 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn);
1107 if (!tlsp->peercert)
1108 tlsp->peercert = X509_dup(cert); /* record failing cert */
1109 return 0; /* reject */
1111 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
1112 "tls_try_verify_hosts)\n");
1113 tlsp->verify_override = TRUE;
1116 else if (depth != 0)
1118 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
1119 #ifndef DISABLE_OCSP
1120 if (tlsp == &tls_out && client_static_state->u_ocsp.client.verify_store)
1121 { /* client, wanting stapling */
1122 /* Add the server cert's signing chain as the one
1123 for the verification of the OCSP stapled information. */
1125 if (!X509_STORE_add_cert(client_static_state->u_ocsp.client.verify_store,
1128 sk_X509_push(client_static_state->verify_stack, cert);
1131 #ifndef DISABLE_EVENT
1132 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
1133 return 0; /* reject, with peercert set */
1138 const uschar * verify_cert_hostnames;
1140 if ( tlsp == &tls_out
1141 && ((verify_cert_hostnames = client_static_state->verify_cert_hostnames)))
1142 /* client, wanting hostname check */
1145 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
1146 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
1147 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
1149 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
1150 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
1153 const uschar * list = verify_cert_hostnames;
1156 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
1157 if ((rc = X509_check_host(cert, CCS name, 0,
1158 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
1159 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
1164 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1165 tlsp == &tls_out ? deliver_host_address : sender_host_address);
1172 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
1175 uschar * extra = verify_mode
1176 ? string_sprintf(" (during %c-verify for [%s])",
1177 *verify_mode, sender_host_address)
1179 log_write(0, LOG_MAIN,
1180 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
1181 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1182 extra, dn, verify_cert_hostnames);
1186 if (!tlsp->peercert)
1187 tlsp->peercert = X509_dup(cert); /* record failing cert */
1188 return 0; /* reject */
1190 DEBUG(D_tls) debug_printf("SSL verify name failure overridden (host in "
1191 "tls_try_verify_hosts)\n");
1192 tlsp->verify_override = TRUE;
1196 #ifndef DISABLE_EVENT
1197 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
1198 return 0; /* reject, with peercert set */
1201 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
1202 *calledp ? "" : " authenticated", dn);
1206 return 1; /* accept, at least for this level */
1210 verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
1212 return verify_callback(preverify_ok, x509ctx, &tls_out,
1213 &client_verify_callback_called, &client_verify_optional);
1217 verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
1219 return verify_callback(preverify_ok, x509ctx, &tls_in,
1220 &server_verify_callback_called, &server_verify_optional);
1226 /* This gets called *by* the dane library verify callback, which interposes
1230 verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
1232 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
1234 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
1235 #ifndef DISABLE_EVENT
1236 BOOL dummy_called, optional = FALSE;
1239 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
1241 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
1242 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1243 deliver_host_address);
1246 dn[sizeof(dn)-1] = '\0';
1248 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
1249 preverify_ok ? "ok":"BAD", depth, dn);
1251 #ifndef DISABLE_EVENT
1252 if (verify_event(&tls_out, cert, depth, dn,
1253 &dummy_called, &optional, US"DANE"))
1254 return 0; /* reject, with peercert set */
1257 if (preverify_ok == 1)
1259 tls_out.dane_verified = TRUE;
1260 #ifndef DISABLE_OCSP
1261 if (client_static_state->u_ocsp.client.verify_store)
1262 { /* client, wanting stapling */
1263 /* Add the server cert's signing chain as the one
1264 for the verification of the OCSP stapled information. */
1266 if (!X509_STORE_add_cert(client_static_state->u_ocsp.client.verify_store,
1269 sk_X509_push(client_static_state->verify_stack, cert);
1275 int err = X509_STORE_CTX_get_error(x509ctx);
1277 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
1278 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
1281 return preverify_ok;
1284 #endif /*SUPPORT_DANE*/
1287 #ifndef DISABLE_OCSP
1288 /*************************************************
1289 * Load OCSP information into state *
1290 *************************************************/
1291 /* Called to load the server OCSP response from the given file into memory, once
1292 caller has determined this is needed. Checks validity. Debugs a message
1295 ASSUMES: single response, for single cert.
1298 state various parts of session state
1299 filename the filename putatively holding an OCSP response
1300 is_pem file is PEM format; otherwise is DER
1304 ocsp_load_response(exim_openssl_state_st * state, const uschar * filename,
1308 OCSP_RESPONSE * resp;
1309 OCSP_BASICRESP * basic_response;
1310 OCSP_SINGLERESP * single_response;
1311 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
1312 STACK_OF(X509) * sk;
1313 unsigned long verify_flags;
1314 int status, reason, i;
1317 debug_printf("tls_ocsp_file (%s) '%s'\n", is_pem ? "PEM" : "DER", filename);
1319 if (!filename || !*filename) return;
1322 if (!(bio = BIO_new_file(CS filename, "rb")))
1324 log_write(0, LOG_MAIN|LOG_PANIC,
1325 "Failed to open OCSP response file \"%s\": %.100s",
1326 filename, ERR_reason_error_string(ERR_get_error()));
1332 uschar * data, * freep;
1335 if (!PEM_read_bio(bio, &dummy, &dummy, &data, &len))
1337 log_write(0, LOG_MAIN|LOG_PANIC, "Failed to read PEM file \"%s\": %.100s",
1338 filename, ERR_reason_error_string(ERR_get_error()));
1342 resp = d2i_OCSP_RESPONSE(NULL, CUSS &data, len);
1343 OPENSSL_free(freep);
1346 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
1351 log_write(0, LOG_MAIN|LOG_PANIC, "Error reading OCSP response from \"%s\": %s",
1352 filename, ERR_reason_error_string(ERR_get_error()));
1356 if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
1358 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
1359 OCSP_response_status_str(status), status);
1365 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1366 OCSP_RESPONSE_print(bp, resp, 0); /* extreme debug: stapling content */
1371 if (!(basic_response = OCSP_response_get1_basic(resp)))
1374 debug_printf("OCSP response parse error: unable to extract basic response.\n");
1378 sk = state->verify_stack;
1379 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
1381 /* May need to expose ability to adjust those flags?
1382 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
1383 OCSP_TRUSTOTHER OCSP_NOINTERN */
1385 /* This does a full verify on the OCSP proof before we load it for serving
1386 up; possibly overkill - just date-checks might be nice enough.
1388 OCSP_basic_verify takes a "store" arg, but does not
1389 use it for the chain verification, which is all we do
1390 when OCSP_NOVERIFY is set. The content from the wire
1391 "basic_response" and a cert-stack "sk" are all that is used.
1393 We have a stack, loaded in setup_certs() if tls_verify_certificates
1394 was a file (not a directory, or "system"). It is unfortunate we
1395 cannot used the connection context store, as that would neatly
1396 handle the "system" case too, but there seems to be no library
1397 function for getting a stack from a store.
1398 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
1399 We do not free the stack since it could be needed a second time for
1402 Separately we might try to replace using OCSP_basic_verify() - which seems to not
1403 be a public interface into the OpenSSL library (there's no manual entry) -
1404 But what with? We also use OCSP_basic_verify in the client stapling callback.
1405 And there we NEED it; we must verify that status... unless the
1406 library does it for us anyway? */
1408 if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0)
1412 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1413 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
1418 /* Here's the simplifying assumption: there's only one response, for the
1419 one certificate we use, and nothing for anything else in a chain. If this
1420 proves false, we need to extract a cert id from our issued cert
1421 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
1422 right cert in the stack and then calls OCSP_single_get0_status()).
1424 I'm hoping to avoid reworking a bunch more of how we handle state here.
1426 XXX that will change when we add support for (TLS1.3) whole-chain stapling
1429 if (!(single_response = OCSP_resp_get0(basic_response, 0)))
1432 debug_printf("Unable to get first response from OCSP basic response.\n");
1436 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
1437 if (status != V_OCSP_CERTSTATUS_GOOD)
1439 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
1440 OCSP_cert_status_str(status), status,
1441 OCSP_crl_reason_str(reason), reason);
1445 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1447 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
1452 /* Add the resp to the list used by tls_server_stapling_cb() */
1454 ocsp_resplist ** op = &state->u_ocsp.server.olist, * oentry;
1455 while (oentry = *op)
1457 *op = oentry = store_get(sizeof(ocsp_resplist), GET_UNTAINTED);
1458 oentry->next = NULL;
1459 oentry->resp = resp;
1464 if (f.running_in_test_harness)
1466 extern char ** environ;
1467 if (environ) for (uschar ** p = USS environ; *p; p++)
1468 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1470 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
1471 goto supply_response;
1479 ocsp_free_response_list(exim_openssl_state_st * state)
1481 for (ocsp_resplist * olist = state->u_ocsp.server.olist; olist;
1482 olist = olist->next)
1483 OCSP_RESPONSE_free(olist->resp);
1484 state->u_ocsp.server.olist = NULL;
1486 #endif /*!DISABLE_OCSP*/
1493 tls_add_certfile(SSL_CTX * sctx, exim_openssl_state_st * cbinfo, uschar * file,
1496 DEBUG(D_tls) debug_printf("tls_certificate file '%s'\n", file);
1497 if (!SSL_CTX_use_certificate_chain_file(sctx, CS file))
1498 return tls_error(string_sprintf(
1499 "SSL_CTX_use_certificate_chain_file file=%s", file),
1500 cbinfo->host, NULL, errstr);
1505 tls_add_pkeyfile(SSL_CTX * sctx, exim_openssl_state_st * cbinfo, uschar * file,
1508 DEBUG(D_tls) debug_printf("tls_privatekey file '%s'\n", file);
1509 if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM))
1510 return tls_error(string_sprintf(
1511 "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr);
1518 /* Called once during tls_init and possibly again during TLS setup, for a
1519 new context, if Server Name Indication was used and tls_sni was seen in
1520 the certificate string.
1523 sctx the SSL_CTX* to update
1524 state various parts of session state
1525 errstr error string pointer
1527 Returns: OK/DEFER/FAIL
1531 tls_expand_session_files(SSL_CTX * sctx, exim_openssl_state_st * state,
1536 if (!state->certificate)
1538 if (!state->is_server) /* client */
1541 if (tls_install_selfsign(sctx, errstr) != OK)
1548 if ( !reexpand_tls_files_for_sni
1549 && ( Ustrstr(state->certificate, US"tls_sni")
1550 || Ustrstr(state->certificate, US"tls_in_sni")
1551 || Ustrstr(state->certificate, US"tls_out_sni")
1553 reexpand_tls_files_for_sni = TRUE;
1555 if (!expand_check(state->certificate, US"tls_certificate", &expanded, errstr))
1559 if (state->is_server)
1561 const uschar * file_list = expanded;
1564 #ifndef DISABLE_OCSP
1565 const uschar * olist = state->u_ocsp.server.file;
1568 BOOL fmt_pem = FALSE;
1571 if (!expand_check(olist, US"tls_ocsp_file", USS &olist, errstr))
1573 if (olist && !*olist)
1576 /* If doing a re-expand after SNI, avoid reloading the OCSP
1577 responses when the list of filenames has not changed.
1578 The creds-invali on content change wipes file_expanded, so that
1579 always reloads here. */
1581 if ( state->u_ocsp.server.file_expanded && olist
1582 && (Ustrcmp(olist, state->u_ocsp.server.file_expanded) == 0))
1584 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
1589 ocsp_free_response_list(state);
1590 state->u_ocsp.server.file_expanded = olist;
1594 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1596 if ((err = tls_add_certfile(sctx, state, file, errstr)))
1599 #ifndef DISABLE_OCSP
1601 if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1603 if (Ustrncmp(ofile, US"PEM ", 4) == 0)
1608 else if (Ustrncmp(ofile, US"DER ", 4) == 0)
1613 ocsp_load_response(state, ofile, fmt_pem);
1616 DEBUG(D_tls) debug_printf("ran out of ocsp file list\n");
1620 else /* would there ever be a need for multiple client certs? */
1621 if ((err = tls_add_certfile(sctx, state, expanded, errstr)))
1624 if ( state->privatekey
1625 && !expand_check(state->privatekey, US"tls_privatekey", &expanded, errstr))
1628 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1629 of the expansion is an empty string, ignore it also, and assume the private
1630 key is in the same file as the certificate. */
1632 if (expanded && *expanded)
1633 if (state->is_server)
1635 const uschar * file_list = expanded;
1639 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1640 if ((err = tls_add_pkeyfile(sctx, state, file, errstr)))
1643 else /* would there ever be a need for multiple client certs? */
1644 if ((err = tls_add_pkeyfile(sctx, state, expanded, errstr)))
1654 /**************************************************
1655 * One-time init credentials for server and client *
1656 **************************************************/
1659 normalise_ciphers(uschar ** ciphers, const uschar * pre_expansion_ciphers)
1661 uschar * s = *ciphers;
1663 if (!s || !Ustrchr(s, '_')) return; /* no change needed */
1665 if (s == pre_expansion_ciphers)
1666 s = string_copy(s); /* get writable copy */
1668 for (uschar * t = s; *t; t++) if (*t == '_') *t = '-';
1673 server_load_ciphers(SSL_CTX * ctx, exim_openssl_state_st * state,
1674 uschar * ciphers, uschar ** errstr)
1676 DEBUG(D_tls) debug_printf("required ciphers: %s\n", ciphers);
1677 if (!SSL_CTX_set_cipher_list(ctx, CS ciphers))
1678 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
1679 state->server_cipher_list = ciphers;
1686 lib_ctx_new(SSL_CTX ** ctxp, host_item * host, uschar ** errstr)
1689 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1690 if (!(ctx = SSL_CTX_new(host ? TLS_client_method() : TLS_server_method())))
1692 if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
1694 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
1696 /* Set up the information callback, which outputs if debugging is at a suitable
1701 SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
1702 #if defined(EXIM_HAVE_OPESSL_TRACE) && !defined(OPENSSL_NO_SSL_TRACE)
1703 /* this needs a debug build of OpenSSL */
1704 SSL_CTX_set_msg_callback(ctx, (void (*)())SSL_trace);
1706 #ifdef OPENSSL_HAVE_KEYLOG_CB
1707 SSL_CTX_set_keylog_callback(ctx, (void (*)())keylog_callback);
1711 /* Automatically re-try reads/writes after renegotiation. */
1712 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
1719 tls_server_creds_init(void)
1722 uschar * dummy_errstr;
1723 unsigned lifetime = 0;
1727 state_server.lib_state = null_tls_preload;
1729 if (lib_ctx_new(&ctx, NULL, &dummy_errstr) != OK)
1731 state_server.lib_state.lib_ctx = ctx;
1733 /* Preload DH params and EC curve */
1735 if (opt_unset_or_noexpand(tls_dhparam))
1737 DEBUG(D_tls) debug_printf("TLS: preloading DH params for server\n");
1738 if (init_dh(ctx, tls_dhparam, &dummy_errstr))
1739 state_server.lib_state.dh = TRUE;
1742 DEBUG(D_tls) debug_printf("TLS: not preloading DH params for server\n");
1743 if (opt_unset_or_noexpand(tls_eccurve))
1745 DEBUG(D_tls) debug_printf("TLS: preloading ECDH curve for server\n");
1746 if (init_ecdh(ctx, &dummy_errstr))
1747 state_server.lib_state.ecdh = TRUE;
1750 DEBUG(D_tls) debug_printf("TLS: not preloading ECDH curve for server\n");
1752 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1753 /* If we can, preload the server-side cert, key and ocsp */
1755 if ( opt_set_and_noexpand(tls_certificate)
1756 # ifndef DISABLE_OCSP
1757 && opt_unset_or_noexpand(tls_ocsp_file)
1759 && opt_unset_or_noexpand(tls_privatekey))
1761 /* Set watches on the filenames. The implementation does de-duplication
1762 so we can just blindly do them all. */
1764 if ( tls_set_watch(tls_certificate, TRUE)
1765 # ifndef DISABLE_OCSP
1766 && tls_set_watch(tls_ocsp_file, TRUE)
1768 && tls_set_watch(tls_privatekey, TRUE))
1770 state_server.certificate = tls_certificate;
1771 state_server.privatekey = tls_privatekey;
1772 #ifndef DISABLE_OCSP
1773 state_server.u_ocsp.server.file = tls_ocsp_file;
1776 DEBUG(D_tls) debug_printf("TLS: preloading server certs\n");
1777 if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
1778 state_server.lib_state.conn_certs = TRUE;
1781 else if ( !tls_certificate && !tls_privatekey
1782 # ifndef DISABLE_OCSP
1786 { /* Generate & preload a selfsigned cert. No files to watch. */
1787 if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
1789 state_server.lib_state.conn_certs = TRUE;
1790 lifetime = f.running_in_test_harness ? 2 : 60 * 60; /* 1 hour */
1794 DEBUG(D_tls) debug_printf("TLS: not preloading server certs\n");
1797 /* If we can, preload the Authorities for checking client certs against.
1798 Actual choice to do verify is made (tls_{,try_}verify_hosts)
1799 at TLS conn startup */
1801 if ( opt_set_and_noexpand(tls_verify_certificates)
1802 && opt_unset_or_noexpand(tls_crl))
1804 /* Watch the default dir also as they are always included */
1806 if ( tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
1807 && tls_set_watch(tls_verify_certificates, FALSE)
1808 && tls_set_watch(tls_crl, FALSE))
1810 DEBUG(D_tls) debug_printf("TLS: preloading CA bundle for server\n");
1812 if (setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, &dummy_errstr)
1814 state_server.lib_state.cabundle = TRUE;
1818 DEBUG(D_tls) debug_printf("TLS: not preloading CA bundle for server\n");
1819 #endif /* EXIM_HAVE_INOTIFY */
1822 /* If we can, preload the ciphers control string */
1824 if (opt_set_and_noexpand(tls_require_ciphers))
1826 DEBUG(D_tls) debug_printf("TLS: preloading cipher list for server\n");
1827 normalise_ciphers(&tls_require_ciphers, tls_require_ciphers);
1828 if (server_load_ciphers(ctx, &state_server, tls_require_ciphers,
1829 &dummy_errstr) == OK)
1830 state_server.lib_state.pri_string = TRUE;
1833 DEBUG(D_tls) debug_printf("TLS: not preloading cipher list for server\n");
1840 /* Preload whatever creds are static, onto a transport. The client can then
1841 just copy the pointer as it starts up.
1842 Called from the daemon after a cache-invalidate with watch set; called from
1843 a queue-run startup with watch clear. */
1846 tls_client_creds_init(transport_instance * t, BOOL watch)
1848 smtp_transport_options_block * ob = t->options_block;
1849 exim_openssl_state_st tpt_dummy_state;
1850 host_item * dummy_host = (host_item *)1;
1851 uschar * dummy_errstr;
1856 ob->tls_preload = null_tls_preload;
1857 if (lib_ctx_new(&ctx, dummy_host, &dummy_errstr) != OK)
1859 ob->tls_preload.lib_ctx = ctx;
1861 tpt_dummy_state.lib_state = ob->tls_preload;
1863 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1864 if ( opt_set_and_noexpand(ob->tls_certificate)
1865 && opt_unset_or_noexpand(ob->tls_privatekey))
1868 || ( tls_set_watch(ob->tls_certificate, FALSE)
1869 && tls_set_watch(ob->tls_privatekey, FALSE)
1872 uschar * pkey = ob->tls_privatekey;
1875 debug_printf("TLS: preloading client certs for transport '%s'\n",t->name);
1877 if ( tls_add_certfile(ctx, &tpt_dummy_state, ob->tls_certificate,
1879 && tls_add_pkeyfile(ctx, &tpt_dummy_state,
1880 pkey ? pkey : ob->tls_certificate,
1883 ob->tls_preload.conn_certs = TRUE;
1888 debug_printf("TLS: not preloading client certs, for transport '%s'\n", t->name);
1891 if ( opt_set_and_noexpand(ob->tls_verify_certificates)
1892 && opt_unset_or_noexpand(ob->tls_crl))
1895 || tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
1896 && tls_set_watch(ob->tls_verify_certificates, FALSE)
1897 && tls_set_watch(ob->tls_crl, FALSE)
1901 debug_printf("TLS: preloading CA bundle for transport '%s'\n", t->name);
1903 if (setup_certs(ctx, ob->tls_verify_certificates,
1904 ob->tls_crl, dummy_host, &dummy_errstr) == OK)
1905 ob->tls_preload.cabundle = TRUE;
1910 debug_printf("TLS: not preloading CA bundle, for transport '%s'\n", t->name);
1912 #endif /*EXIM_HAVE_INOTIFY*/
1916 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1917 /* Invalidate the creds cached, by dropping the current ones.
1918 Call when we notice one of the source files has changed. */
1921 tls_server_creds_invalidate(void)
1923 SSL_CTX_free(state_server.lib_state.lib_ctx);
1924 state_server.lib_state = null_tls_preload;
1925 #ifndef DISABLE_OCSP
1926 state_server.u_ocsp.server.file_expanded = NULL;
1932 tls_client_creds_invalidate(transport_instance * t)
1934 smtp_transport_options_block * ob = t->options_block;
1935 SSL_CTX_free(ob->tls_preload.lib_ctx);
1936 ob->tls_preload = null_tls_preload;
1942 tls_server_creds_invalidate(void)
1946 tls_client_creds_invalidate(transport_instance * t)
1949 #endif /*EXIM_HAVE_INOTIFY*/
1953 #ifndef DISABLE_OCSP
1955 x509_store_dump_cert_s_names(X509_STORE * store)
1957 STACK_OF(X509_OBJECT) * roots= store->objs;
1958 static uschar name[256];
1960 for (int i= 0; i < sk_X509_OBJECT_num(roots); i++)
1962 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
1963 if(tmp_obj->type == X509_LU_X509)
1965 X509_NAME * sn = X509_get_subject_name(tmp_obj->data.x509);
1966 if (X509_NAME_oneline(sn, CS name, sizeof(name)))
1968 name[sizeof(name)-1] = '\0';
1969 debug_printf(" %s\n", name);
1978 #ifndef DISABLE_TLS_RESUME
1979 /* Manage the keysets used for encrypting the session tickets, on the server. */
1981 typedef struct { /* Session ticket encryption key */
1984 const EVP_CIPHER * aes_cipher;
1985 uschar aes_key[32]; /* size needed depends on cipher. aes_128 implies 128/8 = 16? */
1986 # if OPENSSL_VERSION_NUMBER < 0x30000000L
1987 const EVP_MD * hmac_hash;
1989 const uschar * hmac_hashname;
1991 uschar hmac_key[16];
1996 static exim_stek exim_tk; /* current key */
1997 static exim_stek exim_tk_old; /* previous key */
2002 time_t t = time(NULL);
2004 if (exim_tk.name[0])
2006 if (exim_tk.renew >= t) return;
2007 exim_tk_old = exim_tk;
2010 if (f.running_in_test_harness) ssl_session_timeout = 6;
2012 DEBUG(D_tls) debug_printf("OpenSSL: %s STEK\n", exim_tk.name[0] ? "rotating" : "creating");
2013 if (RAND_bytes(exim_tk.aes_key, sizeof(exim_tk.aes_key)) <= 0) return;
2014 if (RAND_bytes(exim_tk.hmac_key, sizeof(exim_tk.hmac_key)) <= 0) return;
2015 if (RAND_bytes(exim_tk.name+1, sizeof(exim_tk.name)-1) <= 0) return;
2017 exim_tk.name[0] = 'E';
2018 exim_tk.aes_cipher = EVP_aes_256_cbc();
2019 # if OPENSSL_VERSION_NUMBER < 0x30000000L
2020 exim_tk.hmac_hash = EVP_sha256();
2022 exim_tk.hmac_hashname = US "sha256";
2024 exim_tk.expire = t + ssl_session_timeout;
2025 exim_tk.renew = t + ssl_session_timeout/2;
2031 if (!exim_tk.name[0]) return NULL;
2036 tk_find(const uschar * name)
2038 return memcmp(name, exim_tk.name, sizeof(exim_tk.name)) == 0 ? &exim_tk
2039 : memcmp(name, exim_tk_old.name, sizeof(exim_tk_old.name)) == 0 ? &exim_tk_old
2046 # if OPENSSL_VERSION_NUMBER < 0x30000000L
2054 /*XXX will want these dependent on the ssl session strength */
2055 # if OPENSSL_VERSION_NUMBER < 0x30000000L
2056 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
2057 key->hmac_hash, NULL);
2060 OSSL_PARAM params[3];
2061 uschar * hk = string_copy(key->hmac_hashname); /* need nonconst */
2062 params[0] = OSSL_PARAM_construct_octet_string("key", key->hmac_key, sizeof(key->hmac_key));
2063 params[1] = OSSL_PARAM_construct_utf8_string("digest", CS hk, 0);
2064 params[2] = OSSL_PARAM_construct_end();
2065 if (EVP_MAC_CTX_set_params(hctx, params) == 0)
2067 DEBUG(D_tls) debug_printf("EVP_MAC_CTX_set_params: %s\n",
2068 ERR_reason_error_string(ERR_get_error()));
2069 return 0; /* error in mac initialisation */
2076 /* Callback for session tickets, on server */
2078 ticket_key_callback(SSL * ssl, uschar key_name[16],
2079 uschar * iv, EVP_CIPHER_CTX * c_ctx,
2080 # if OPENSSL_VERSION_NUMBER < 0x30000000L
2087 tls_support * tlsp = state_server.tlsp;
2092 DEBUG(D_tls) debug_printf("ticket_key_callback: create new session\n");
2093 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
2095 if (RAND_bytes(iv, EVP_MAX_IV_LENGTH) <= 0)
2096 return -1; /* insufficient random */
2098 if (!(key = tk_current())) /* current key doesn't exist or isn't valid */
2099 return 0; /* key couldn't be created */
2100 memcpy(key_name, key->name, 16);
2101 DEBUG(D_tls) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - time(NULL));
2103 if (tk_hmac_init(hctx, key) == 0) return 0;
2104 EVP_EncryptInit_ex(c_ctx, key->aes_cipher, NULL, key->aes_key, iv);
2106 DEBUG(D_tls) debug_printf("ticket created\n");
2111 time_t now = time(NULL);
2113 DEBUG(D_tls) debug_printf("ticket_key_callback: retrieve session\n");
2114 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
2116 if (!(key = tk_find(key_name)) || key->expire < now)
2120 debug_printf("ticket not usable (%s)\n", key ? "expired" : "not found");
2121 if (key) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - now);
2126 if (tk_hmac_init(hctx, key) == 0) return 0;
2127 EVP_DecryptInit_ex(c_ctx, key->aes_cipher, NULL, key->aes_key, iv);
2129 DEBUG(D_tls) debug_printf("ticket usable, STEK expire " TIME_T_FMT "\n", key->expire - now);
2131 /* The ticket lifetime and renewal are the same as the STEK lifetime and
2132 renewal, which is overenthusiastic. A factor of, say, 3x longer STEK would
2133 be better. To do that we'd have to encode ticket lifetime in the name as
2134 we don't yet see the restored session. Could check posthandshake for TLS1.3
2135 and trigger a new ticket then, but cannot do that for TLS1.2 */
2136 return key->renew < now ? 2 : 1;
2139 #endif /* !DISABLE_TLS_RESUME */
2144 setup_cert_verify(SSL_CTX * ctx, BOOL optional,
2145 int (*cert_vfy_cb)(int, X509_STORE_CTX *))
2147 /* If verification is optional, don't fail if no certificate */
2149 SSL_CTX_set_verify(ctx,
2150 SSL_VERIFY_PEER | (optional ? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
2155 /*************************************************
2156 * Callback to handle SNI *
2157 *************************************************/
2159 /* Called when acting as server during the TLS session setup if a Server Name
2160 Indication extension was sent by the client.
2162 API documentation is OpenSSL s_server.c implementation.
2165 s SSL* of the current session
2166 ad unknown (part of OpenSSL API) (unused)
2167 arg Callback of "our" registered data
2169 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
2171 XXX might need to change to using ClientHello callback,
2172 per https://www.openssl.org/docs/manmaster/man3/SSL_client_hello_cb_fn.html
2175 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2177 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
2179 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
2180 exim_openssl_state_st *state = (exim_openssl_state_st *) arg;
2182 int old_pool = store_pool;
2183 uschar * dummy_errstr;
2186 return SSL_TLSEXT_ERR_OK;
2188 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
2189 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
2191 /* Make the extension value available for expansion */
2192 store_pool = POOL_PERM;
2193 tls_in.sni = string_copy_taint(US servername, GET_TAINTED);
2194 store_pool = old_pool;
2196 if (!reexpand_tls_files_for_sni)
2197 return SSL_TLSEXT_ERR_OK;
2199 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
2200 not confident that memcpy wouldn't break some internal reference counting.
2201 Especially since there's a references struct member, which would be off. */
2203 if (lib_ctx_new(&server_sni, NULL, &dummy_errstr) != OK)
2206 /* Not sure how many of these are actually needed, since SSL object
2207 already exists. Might even need this selfsame callback, for reneg? */
2210 SSL_CTX * ctx = state_server.lib_state.lib_ctx;
2211 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(ctx));
2212 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(ctx));
2213 SSL_CTX_set_min_proto_version(server_sni, SSL3_VERSION);
2214 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(ctx));
2215 SSL_CTX_clear_options(server_sni, ~SSL_CTX_get_options(ctx));
2216 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(ctx));
2217 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
2218 SSL_CTX_set_tlsext_servername_arg(server_sni, state);
2221 if ( !init_dh(server_sni, state->dhparam, &dummy_errstr)
2222 || !init_ecdh(server_sni, &dummy_errstr)
2226 if ( state->server_cipher_list
2227 && !SSL_CTX_set_cipher_list(server_sni, CS state->server_cipher_list))
2230 #ifndef DISABLE_OCSP
2231 if (state->u_ocsp.server.file)
2233 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
2234 SSL_CTX_set_tlsext_status_arg(server_sni, state);
2240 if ( !expand_check(tls_verify_certificates, US"tls_verify_certificates",
2241 &expcerts, &dummy_errstr)
2242 || (rc = setup_certs(server_sni, expcerts, tls_crl, NULL,
2243 &dummy_errstr)) != OK)
2246 if (expcerts && *expcerts)
2247 setup_cert_verify(server_sni, FALSE, verify_callback_server);
2250 /* do this after setup_certs, because this can require the certs for verifying
2251 OCSP information. */
2252 if ((rc = tls_expand_session_files(server_sni, state, &dummy_errstr)) != OK)
2255 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
2256 SSL_set_SSL_CTX(s, server_sni);
2257 return SSL_TLSEXT_ERR_OK;
2259 bad: return SSL_TLSEXT_ERR_ALERT_FATAL;
2261 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
2266 #ifdef EXIM_HAVE_ALPN
2267 /*************************************************
2268 * Callback to handle ALPN *
2269 *************************************************/
2271 /* Called on server if tls_alpn nonblank after expansion,
2272 when client offers ALPN, after the SNI callback.
2273 If set and not matching the list then we dump the connection */
2276 tls_server_alpn_cb(SSL *ssl, const uschar ** out, uschar * outlen,
2277 const uschar * in, unsigned int inlen, void * arg)
2279 server_seen_alpn = TRUE;
2282 debug_printf("Received TLS ALPN offer:");
2283 for (int pos = 0, siz; pos < inlen; pos += siz+1)
2286 if (pos + 1 + siz > inlen) siz = inlen - pos - 1;
2287 debug_printf(" '%.*s'", siz, in + pos + 1);
2289 debug_printf(". Our list: '%s'\n", tls_alpn);
2292 /* Look for an acceptable ALPN */
2294 if ( inlen > 1 /* at least one name */
2295 && in[0]+1 == inlen /* filling the vector, so exactly one name */
2298 const uschar * list = tls_alpn;
2300 for (uschar * name; name = string_nextinlist(&list, &sep, NULL, 0); )
2301 if (Ustrncmp(in+1, name, in[0]) == 0)
2303 *out = in+1; /* we checked for exactly one, so can just point to it */
2305 return SSL_TLSEXT_ERR_OK; /* use ALPN */
2309 /* More than one name from clilent, or name did not match our list. */
2311 /* This will be fatal to the TLS conn; would be nice to kill TCP also.
2312 Maybe as an option in future; for now leave control to the config (must-tls). */
2314 DEBUG(D_tls) debug_printf("TLS ALPN rejected\n");
2315 return SSL_TLSEXT_ERR_ALERT_FATAL;
2317 #endif /* EXIM_HAVE_ALPN */
2321 #ifndef DISABLE_OCSP
2323 /*************************************************
2324 * Callback to handle OCSP Stapling *
2325 *************************************************/
2327 /* Called when acting as server during the TLS session setup if the client
2328 requests OCSP information with a Certificate Status Request.
2330 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
2336 tls_server_stapling_cb(SSL *s, void *arg)
2338 const exim_openssl_state_st * state = arg;
2339 ocsp_resplist * olist = state->u_ocsp.server.olist;
2340 uschar * response_der; /*XXX blob */
2341 int response_der_len;
2344 debug_printf("Received TLS status request (OCSP stapling); %s response list\n",
2345 olist ? "have" : "lack");
2347 tls_in.ocsp = OCSP_NOT_RESP;
2349 return SSL_TLSEXT_ERR_NOACK;
2351 #ifdef EXIM_HAVE_OPESSL_GET0_SERIAL
2353 const X509 * cert_sent = SSL_get_certificate(s);
2354 const ASN1_INTEGER * cert_serial = X509_get0_serialNumber(cert_sent);
2355 const BIGNUM * cert_bn = ASN1_INTEGER_to_BN(cert_serial, NULL);
2357 for (; olist; olist = olist->next)
2359 OCSP_BASICRESP * bs = OCSP_response_get1_basic(olist->resp);
2360 const OCSP_SINGLERESP * single = OCSP_resp_get0(bs, 0);
2361 const OCSP_CERTID * cid = OCSP_SINGLERESP_get0_id(single);
2362 ASN1_INTEGER * res_cert_serial;
2363 const BIGNUM * resp_bn;
2364 ASN1_OCTET_STRING * res_cert_iNameHash;
2367 (void) OCSP_id_get0_info(&res_cert_iNameHash, NULL, NULL, &res_cert_serial,
2368 (OCSP_CERTID *) cid);
2369 resp_bn = ASN1_INTEGER_to_BN(res_cert_serial, NULL);
2373 debug_printf("cert serial: %s\n", BN_bn2hex(cert_bn));
2374 debug_printf("resp serial: %s\n", BN_bn2hex(resp_bn));
2377 if (BN_cmp(cert_bn, resp_bn) == 0)
2379 DEBUG(D_tls) debug_printf("matched serial for ocsp\n");
2381 /*XXX TODO: check the rest of the list for duplicate matches.
2382 If any, need to also check the Issuer Name hash.
2383 Without this, we will provide the wrong status in the case of
2388 DEBUG(D_tls) debug_printf("not match serial for ocsp\n");
2392 DEBUG(D_tls) debug_printf("failed to find match for ocsp\n");
2393 return SSL_TLSEXT_ERR_NOACK;
2399 DEBUG(D_tls) debug_printf("OpenSSL version too early to support multi-leaf OCSP\n");
2400 return SSL_TLSEXT_ERR_NOACK;
2404 /*XXX could we do the i2d earlier, rather than during the callback? */
2405 response_der = NULL;
2406 response_der_len = i2d_OCSP_RESPONSE(olist->resp, &response_der);
2407 if (response_der_len <= 0)
2408 return SSL_TLSEXT_ERR_NOACK;
2410 SSL_set_tlsext_status_ocsp_resp(state_server.lib_state.lib_ssl,
2411 response_der, response_der_len);
2412 tls_in.ocsp = OCSP_VFIED;
2413 return SSL_TLSEXT_ERR_OK;
2418 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
2420 BIO_printf(bp, "\t%s: ", str);
2421 ASN1_GENERALIZEDTIME_print(bp, time);
2426 tls_client_stapling_cb(SSL * ssl, void * arg)
2428 exim_openssl_state_st * cbinfo = arg;
2429 const unsigned char * p;
2431 OCSP_RESPONSE * rsp;
2432 OCSP_BASICRESP * bs;
2435 DEBUG(D_tls) debug_printf("Received TLS status callback (OCSP stapling):\n");
2436 len = SSL_get_tlsext_status_ocsp_resp(ssl, &p);
2438 { /* Expect this when we requested ocsp but got none */
2439 if (SSL_session_reused(ssl) && tls_out.ocsp == OCSP_VFIED)
2441 DEBUG(D_tls) debug_printf(" null, but resumed; ocsp vfy stored with session is good\n");
2444 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
2445 log_write(0, LOG_MAIN, "Required TLS certificate status not received");
2447 DEBUG(D_tls) debug_printf(" null\n");
2448 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2451 if (!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
2453 tls_out.ocsp = OCSP_FAILED; /*XXX should use tlsp-> to permit concurrent outbound */
2454 if (LOGGING(tls_cipher))
2455 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
2457 DEBUG(D_tls) debug_printf(" parse error\n");
2461 if (!(bs = OCSP_response_get1_basic(rsp)))
2463 tls_out.ocsp = OCSP_FAILED;
2464 if (LOGGING(tls_cipher))
2465 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
2467 DEBUG(D_tls) debug_printf(" error parsing response\n");
2468 OCSP_RESPONSE_free(rsp);
2472 /* We'd check the nonce here if we'd put one in the request. */
2473 /* However that would defeat cacheability on the server so we don't. */
2475 /* This section of code reworked from OpenSSL apps source;
2476 The OpenSSL Project retains copyright:
2477 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
2481 #ifndef EXIM_HAVE_OCSP_RESP_COUNT
2482 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
2485 DEBUG(D_tls) bp = BIO_new(BIO_s_mem());
2487 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
2489 /* Use the chain that verified the server cert to verify the stapled info */
2490 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
2492 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
2493 cbinfo->u_ocsp.client.verify_store, OCSP_NOEXPLICIT)) <= 0)
2494 if (ERR_peek_error())
2496 tls_out.ocsp = OCSP_FAILED;
2497 if (LOGGING(tls_cipher))
2499 const uschar * errstr = CUS ERR_reason_error_string(ERR_peek_error());
2500 static uschar peerdn[256];
2501 X509_NAME_oneline(X509_get_subject_name(SSL_get_peer_certificate(ssl)),
2502 CS peerdn, sizeof(peerdn));
2503 log_write(0, LOG_MAIN,
2504 "[%s] %s Received TLS cert (DN: '%.*s') status response, "
2505 "itself unverifiable: %s",
2506 sender_host_address, sender_host_name,
2507 (int)sizeof(peerdn), peerdn,
2512 BIO_printf(bp, "OCSP response verify failure\n");
2513 ERR_print_errors(bp);
2514 OCSP_RESPONSE_print(bp, rsp, 0);
2519 DEBUG(D_tls) debug_printf("no explicit trust for OCSP signing"
2520 " in the root CA certificate; ignoring\n");
2522 DEBUG(D_tls) debug_printf("OCSP response well-formed and signed OK\n");
2524 /*XXX So we have a good stapled OCSP status. How do we know
2525 it is for the cert of interest? OpenSSL 1.1.0 has a routine
2526 OCSP_resp_find_status() which matches on a cert id, which presumably
2527 we should use. Making an id needs OCSP_cert_id_new(), which takes
2528 issuerName, issuerKey, serialNumber. Are they all in the cert?
2530 For now, carry on blindly accepting the resp. */
2533 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
2534 OCSP_resp_count(bs) - 1;
2536 sk_OCSP_SINGLERESP_num(sresp) - 1;
2540 OCSP_SINGLERESP * single = OCSP_resp_get0(bs, idx);
2542 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
2544 /*XXX so I can see putting a loop in here to handle a rsp with >1 singleresp
2545 - but what happens with a GnuTLS-style input?
2547 we could do with a debug label for each singleresp
2548 - it has a certID with a serialNumber, but I see no API to get that
2550 status = OCSP_single_get0_status(single, &reason, &rev,
2551 &thisupd, &nextupd);
2555 time_print(bp, "This OCSP Update", thisupd);
2556 if (nextupd) time_print(bp, "Next OCSP Update", nextupd);
2558 if (!OCSP_check_validity(thisupd, nextupd,
2559 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
2561 tls_out.ocsp = OCSP_FAILED;
2562 DEBUG(D_tls) ERR_print_errors(bp);
2563 log_write(0, LOG_MAIN, "OCSP dates invalid");
2567 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
2568 OCSP_cert_status_str(status));
2571 case V_OCSP_CERTSTATUS_GOOD:
2572 continue; /* the idx loop */
2573 case V_OCSP_CERTSTATUS_REVOKED:
2574 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
2575 reason != -1 ? "; reason: " : "",
2576 reason != -1 ? OCSP_crl_reason_str(reason) : "");
2577 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
2580 log_write(0, LOG_MAIN,
2581 "Server certificate status unknown, in OCSP stapling");
2589 tls_out.ocsp = OCSP_VFIED;
2593 tls_out.ocsp = OCSP_FAILED;
2594 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2598 int len = (int) BIO_get_mem_data(bp, CSS &s);
2599 if (len > 0) debug_printf("%.*s", len, s);
2604 OCSP_RESPONSE_free(rsp);
2607 #endif /*!DISABLE_OCSP*/
2610 /*************************************************
2611 * Initialize for TLS *
2612 *************************************************/
2613 /* Called from both server and client code, to do preliminary initialization
2614 of the library. We allocate and return a context structure.
2617 host connected host, if client; NULL if server
2618 ob transport options block, if client; NULL if server
2619 ocsp_file file of stapling info (server); flag for require ocsp (client)
2620 addr address if client; NULL if server (for some randomness)
2621 caller_state place to put pointer to allocated state-struct
2622 errstr error string pointer
2624 Returns: OK/DEFER/FAIL
2628 tls_init(host_item * host, smtp_transport_options_block * ob,
2629 #ifndef DISABLE_OCSP
2632 address_item *addr, exim_openssl_state_st ** caller_state,
2637 exim_openssl_state_st * state;
2640 if (host) /* client */
2642 state = store_malloc(sizeof(exim_openssl_state_st));
2643 memset(state, 0, sizeof(*state));
2644 state->certificate = ob->tls_certificate;
2645 state->privatekey = ob->tls_privatekey;
2646 state->is_server = FALSE;
2647 state->dhparam = NULL;
2648 state->lib_state = ob->tls_preload;
2652 state = &state_server;
2653 state->certificate = tls_certificate;
2654 state->privatekey = tls_privatekey;
2655 state->is_server = TRUE;
2656 state->dhparam = tls_dhparam;
2657 state->lib_state = state_server.lib_state;
2663 if (!state->lib_state.pri_string)
2664 state->server_cipher_list = NULL;
2666 #ifndef DISABLE_EVENT
2667 state->event_action = NULL;
2672 /* It turns out that we need to seed the random number generator this early in
2673 order to get the full complement of ciphers to work. It took me roughly a day
2674 of work to discover this by experiment.
2676 On systems that have /dev/urandom, SSL may automatically seed itself from
2677 there. Otherwise, we have to make something up as best we can. Double check
2680 Although we likely called this before, at daemon startup, this is a chance
2681 to mix in further variable info (time, pid) if needed. */
2683 if (!lib_rand_init(addr))
2684 return tls_error(US"RAND_status", host,
2685 US"unable to seed random number generator", errstr);
2687 /* Apply administrator-supplied work-arounds.
2688 Historically we applied just one requested option,
2689 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
2690 moved to an administrator-controlled list of options to specify and
2691 grandfathered in the first one as the default value for "openssl_options".
2693 No OpenSSL version number checks: the options we accept depend upon the
2694 availability of the option value macros from OpenSSL. */
2697 if (!tls_openssl_options_parse(openssl_options, &init_options))
2698 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
2700 /* Create a context.
2701 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
2702 negotiation in the different methods; as far as I can tell, the only
2703 *_{server,client}_method which allows negotiation is SSLv23, which exists even
2704 when OpenSSL is built without SSLv2 support.
2705 By disabling with openssl_options, we can let admins re-enable with the
2708 if (!(ctx = state->lib_state.lib_ctx))
2710 if ((rc = lib_ctx_new(&ctx, host, errstr)) != OK)
2712 state->lib_state.lib_ctx = ctx;
2715 #ifndef DISABLE_TLS_RESUME
2716 tlsp->resumption = RESUME_SUPPORTED;
2720 #ifndef DISABLE_TLS_RESUME
2721 /* Should the server offer session resumption? */
2722 if (!host && verify_check_host(&tls_resumption_hosts) == OK)
2724 DEBUG(D_tls) debug_printf("tls_resumption_hosts overrides openssl_options\n");
2725 init_options &= ~SSL_OP_NO_TICKET;
2726 tlsp->resumption |= RESUME_SERVER_TICKET; /* server will give ticket on request */
2727 tlsp->host_resumable = TRUE;
2731 SSL_CTX_set_min_proto_version(ctx, SSL3_VERSION);
2732 DEBUG(D_tls) debug_printf("setting SSL CTX options: %016lx\n", init_options);
2733 SSL_CTX_set_options(ctx, init_options);
2735 ulong readback = SSL_CTX_clear_options(ctx, ~init_options);
2736 if (readback != init_options)
2737 return tls_error(string_sprintf(
2738 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
2742 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
2744 /* We'd like to disable session cache unconditionally, but foolish Outlook
2745 Express clients then give up the first TLS connection and make a second one
2746 (which works). Only when there is an IMAP service on the same machine.
2747 Presumably OE is trying to use the cache for A on B. Leave it enabled for
2748 now, until we work out a decent way of presenting control to the config. It
2749 will never be used because we use a new context every time. */
2751 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
2754 /* Initialize with DH parameters if supplied */
2755 /* Initialize ECDH temp key parameter selection */
2759 if (state->lib_state.dh)
2760 { DEBUG(D_tls) debug_printf("TLS: DH params were preloaded\n"); }
2762 if (!init_dh(ctx, state->dhparam, errstr)) return DEFER;
2764 if (state->lib_state.ecdh)
2765 { DEBUG(D_tls) debug_printf("TLS: ECDH curve was preloaded\n"); }
2767 if (!init_ecdh(ctx, errstr)) return DEFER;
2770 /* Set up certificate and key (and perhaps OCSP info) */
2772 if (state->lib_state.conn_certs)
2775 debug_printf("TLS: %s certs were preloaded\n", host ? "client":"server");
2779 #ifndef DISABLE_OCSP
2780 if (!host) /* server */
2782 state->u_ocsp.server.file = ocsp_file;
2783 state->u_ocsp.server.file_expanded = NULL;
2784 state->u_ocsp.server.olist = NULL;
2787 if ((rc = tls_expand_session_files(ctx, state, errstr)) != OK) return rc;
2790 /* If we need to handle SNI or OCSP, do so */
2792 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2793 # ifndef DISABLE_OCSP
2794 if (!(state->verify_stack = sk_X509_new_null()))
2796 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
2801 if (!host) /* server */
2803 # ifndef DISABLE_OCSP
2804 /* We check u_ocsp.server.file, not server.olist, because we care about if
2805 the option exists, not what the current expansion might be, as SNI might
2806 change the certificate and OCSP file in use between now and the time the
2807 callback is invoked. */
2808 if (state->u_ocsp.server.file)
2810 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
2811 SSL_CTX_set_tlsext_status_arg(ctx, state);
2814 /* We always do this, so that $tls_sni is available even if not used in
2816 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
2817 SSL_CTX_set_tlsext_servername_arg(ctx, state);
2819 # ifdef EXIM_HAVE_ALPN
2820 if (tls_alpn && *tls_alpn)
2823 if ( expand_check(tls_alpn, US"tls_alpn", &exp_alpn, errstr)
2824 && *exp_alpn && !isblank(*exp_alpn))
2826 tls_alpn = exp_alpn; /* subprocess so ok to overwrite */
2827 SSL_CTX_set_alpn_select_cb(ctx, tls_server_alpn_cb, state);
2834 # ifndef DISABLE_OCSP
2836 if(ocsp_file) /* wanting stapling */
2838 if (!(state->u_ocsp.client.verify_store = X509_STORE_new()))
2840 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
2843 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
2844 SSL_CTX_set_tlsext_status_arg(ctx, state);
2849 state->verify_cert_hostnames = NULL;
2851 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
2852 /* Set up the RSA callback */
2853 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
2856 /* Finally, set the session cache timeout, and we are done.
2857 The period appears to be also used for (server-generated) session tickets */
2859 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
2860 DEBUG(D_tls) debug_printf("Initialized TLS\n");
2862 *caller_state = state;
2870 /*************************************************
2871 * Get name of cipher in use *
2872 *************************************************/
2875 Argument: pointer to an SSL structure for the connection
2876 pointer to number of bits for cipher
2877 Returns: pointer to allocated string in perm-pool
2881 construct_cipher_name(SSL * ssl, const uschar * ver, int * bits)
2883 int pool = store_pool;
2884 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
2885 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
2886 the accessor functions use const in the prototype. */
2888 const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
2891 SSL_CIPHER_get_bits(c, bits);
2893 store_pool = POOL_PERM;
2894 s = string_sprintf("%s:%s:%u", ver, SSL_CIPHER_get_name(c), *bits);
2896 DEBUG(D_tls) debug_printf("Cipher: %s\n", s);
2901 /* Get IETF-standard name for ciphersuite.
2902 Argument: pointer to an SSL structure for the connection
2903 Returns: pointer to string
2906 static const uschar *
2907 cipher_stdname_ssl(SSL * ssl)
2909 #ifdef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
2910 return CUS SSL_CIPHER_standard_name(SSL_get_current_cipher(ssl));
2912 ushort id = 0xffff & SSL_CIPHER_get_id(SSL_get_current_cipher(ssl));
2913 return cipher_stdname(id >> 8, id & 0xff);
2918 static const uschar *
2919 tlsver_name(SSL * ssl)
2922 int pool = store_pool;
2924 store_pool = POOL_PERM;
2925 s = string_copy(US SSL_get_version(ssl));
2927 if ((p = Ustrchr(s, 'v'))) /* TLSv1.2 -> TLS1.2 */
2928 for (;; p++) if (!(*p = p[1])) break;
2934 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned siz)
2936 /*XXX we might consider a list-of-certs variable for the cert chain.
2937 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
2938 in list-handling functions, also consider the difference between the entire
2939 chain and the elements sent by the peer. */
2941 tlsp->peerdn = NULL;
2943 /* Will have already noted peercert on a verify fail; possibly not the leaf */
2944 if (!tlsp->peercert)
2945 tlsp->peercert = SSL_get_peer_certificate(ssl);
2946 /* Beware anonymous ciphers which lead to server_cert being NULL */
2948 if (!X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, siz))
2949 { DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n"); }
2952 int oldpool = store_pool;
2954 peerdn[siz-1] = '\0'; /* paranoia */
2955 store_pool = POOL_PERM;
2956 tlsp->peerdn = string_copy(peerdn);
2957 store_pool = oldpool;
2959 /* We used to set CV in the cert-verify callbacks (either plain or dane)
2960 but they don't get called on session-resumption. So use the official
2961 interface, which uses the resumed value. Unfortunately this claims verified
2962 when it actually failed but we're in try-verify mode, due to us wanting the
2963 knowlege that it failed so needing to have the callback and forcing a
2964 permissive return. If we don't force it, the TLS startup is failed.
2965 The extra bit of information is set in verify_override in the cb, stashed
2966 for resumption next to the TLS session, and used here. */
2968 if (!tlsp->verify_override)
2969 tlsp->certificate_verified =
2971 tlsp->dane_verified ||
2973 SSL_get_verify_result(ssl) == X509_V_OK;
2981 /*************************************************
2982 * Set up for verifying certificates *
2983 *************************************************/
2985 #ifndef DISABLE_OCSP
2986 /* Load certs from file, return TRUE on success */
2989 chain_from_pem_file(const uschar * file, STACK_OF(X509) ** vp)
2992 STACK_OF(X509) * verify_stack = *vp;
2995 while (sk_X509_num(verify_stack) > 0)
2996 X509_free(sk_X509_pop(verify_stack));
2998 verify_stack = sk_X509_new_null();
3000 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
3001 for (X509 * x; x = PEM_read_bio_X509(bp, NULL, 0, NULL); )
3002 sk_X509_push(verify_stack, x);
3011 /* Called by both client and server startup; on the server possibly
3012 repeated after a Server Name Indication.
3015 sctx SSL_CTX* to initialise
3016 certs certs file, expanded
3017 crl CRL file or NULL
3018 host NULL in a server; the remote host in a client
3019 errstr error string pointer
3021 Returns: OK/DEFER/FAIL
3025 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host,
3028 uschar *expcerts, *expcrl;
3030 if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
3032 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3034 if (expcerts && *expcerts)
3036 /* Tell the library to use its compiled-in location for the system default
3037 CA bundle. Then add the ones specified in the config, if any. */
3039 if (!SSL_CTX_set_default_verify_paths(sctx))
3040 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
3042 if (Ustrcmp(expcerts, "system") != 0 && Ustrncmp(expcerts, "system,", 7) != 0)
3044 struct stat statbuf;
3046 if (Ustat(expcerts, &statbuf) < 0)
3048 log_write(0, LOG_MAIN|LOG_PANIC,
3049 "failed to stat %s for certificates", expcerts);
3055 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
3056 { file = NULL; dir = expcerts; }
3059 STACK_OF(X509) * verify_stack =
3060 #ifndef DISABLE_OCSP
3061 !host ? state_server.verify_stack :
3064 STACK_OF(X509) ** vp = &verify_stack;
3066 file = expcerts; dir = NULL;
3067 #ifndef DISABLE_OCSP
3068 /* In the server if we will be offering an OCSP proof, load chain from
3069 file for verifying the OCSP proof at load time. */
3071 /*XXX Glitch! The file here is tls_verify_certs: the chain for verifying the client cert.
3072 This is inconsistent with the need to verify the OCSP proof of the server cert.
3075 && statbuf.st_size > 0
3076 && state_server.u_ocsp.server.file
3077 && !chain_from_pem_file(file, vp)
3080 log_write(0, LOG_MAIN|LOG_PANIC,
3081 "failed to load cert chain from %s", file);
3087 /* If a certificate file is empty, the load function fails with an
3088 unhelpful error message. If we skip it, we get the correct behaviour (no
3089 certificates are recognized, but the error message is still misleading (it
3090 says no certificate was supplied). But this is better. */
3092 if ( (!file || statbuf.st_size > 0)
3093 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
3094 return tls_error(US"SSL_CTX_load_verify_locations",
3095 host, NULL, errstr);
3097 /* On the server load the list of CAs for which we will accept certs, for
3098 sending to the client. This is only for the one-file
3099 tls_verify_certificates variant.
3100 If a list isn't loaded into the server, but some verify locations are set,
3101 the server end appears to make a wildcard request for client certs.
3102 Meanwhile, the client library as default behaviour *ignores* the list
3103 we send over the wire - see man SSL_CTX_set_client_cert_cb.
3104 Because of this, and that the dir variant is likely only used for
3105 the public-CA bundle (not for a private CA), not worth fixing. */
3109 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
3110 int i = sk_X509_NAME_num(names);
3112 if (!host) SSL_CTX_set_client_CA_list(sctx, names);
3113 DEBUG(D_tls) debug_printf("Added %d additional certificate authorit%s\n",
3114 i, i>1 ? "ies":"y");
3118 debug_printf("Added dir for additional certificate authorities\n");
3122 /* Handle a certificate revocation list. */
3124 #if OPENSSL_VERSION_NUMBER > 0x00907000L
3126 /* This bit of code is now the version supplied by Lars Mainka. (I have
3127 merely reformatted it into the Exim code style.)
3129 "From here I changed the code to add support for multiple crl's
3130 in pem format in one file or to support hashed directory entries in
3131 pem format instead of a file. This method now uses the library function
3132 X509_STORE_load_locations to add the CRL location to the SSL context.
3133 OpenSSL will then handle the verify against CA certs and CRLs by
3134 itself in the verify callback." */
3136 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
3137 if (expcrl && *expcrl)
3139 struct stat statbufcrl;
3140 if (Ustat(expcrl, &statbufcrl) < 0)
3142 log_write(0, LOG_MAIN|LOG_PANIC,
3143 "failed to stat %s for certificates revocation lists", expcrl);
3148 /* is it a file or directory? */
3150 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
3151 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
3155 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
3161 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
3163 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
3164 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
3166 /* setting the flags to check against the complete crl chain */
3168 X509_STORE_set_flags(cvstore,
3169 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
3173 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
3182 tls_dump_keylog(SSL * ssl)
3184 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3185 BIO * bp = BIO_new(BIO_s_mem());
3188 SSL_SESSION_print_keylog(bp, SSL_get_session(ssl));
3189 len = (int) BIO_get_mem_data(bp, CSS &s);
3190 if (len > 0) debug_printf("%.*s", len, s);
3196 /* Channel-binding info for authenticators
3197 See description in https://paquier.xyz/postgresql-2/channel-binding-openssl/
3202 tls_get_channel_binding(SSL * ssl, tls_support * tlsp, const void * taintval)
3207 #ifdef EXIM_HAVE_EXPORT_CHNL_BNGNG
3208 if (SSL_version(ssl) > TLS1_2_VERSION)
3210 /* It's not documented by OpenSSL how big the output buffer must be.
3211 The OpenSSL testcases use 80 bytes but don't say why. The GnuTLS impl only
3212 serves out 32B. RFC 9266 says it is 32B.
3213 Interop fails unless we use the same each end. */
3216 tlsp->channelbind_exporter = TRUE;
3217 taintval = GET_UNTAINTED;
3218 if (SSL_export_keying_material(ssl,
3219 s = store_get((int)len, taintval), len,
3220 "EXPORTER-Channel-Binding", (size_t) 24,
3227 len = SSL_get_peer_finished(ssl, &c, 0);
3228 len = SSL_get_peer_finished(ssl, s = store_get((int)len, taintval), len);
3233 int old_pool = store_pool;
3234 store_pool = POOL_PERM;
3235 tlsp->channelbinding = b64encode_taint(CUS s, (int)len, taintval);
3236 store_pool = old_pool;
3237 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage %p %p\n", tlsp->channelbinding, tlsp);
3242 /*************************************************
3243 * Start a TLS session in a server *
3244 *************************************************/
3245 /* This is called when Exim is running as a server, after having received
3246 the STARTTLS command. It must respond to that command, and then negotiate
3250 errstr pointer to error message
3252 Returns: OK on success
3253 DEFER for errors before the start of the negotiation
3254 FAIL for errors during the negotiation; the server can't
3259 tls_server_start(uschar ** errstr)
3262 uschar * expciphers;
3263 exim_openssl_state_st * dummy_statep;
3266 static uschar peerdn[256];
3268 /* Check for previous activation */
3270 if (tls_in.active.sock >= 0)
3272 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
3273 smtp_printf("554 Already in TLS\r\n", FALSE);
3277 /* Initialize the SSL library. If it fails, it will already have logged
3280 rc = tls_init(NULL, NULL,
3281 #ifndef DISABLE_OCSP
3284 NULL, &dummy_statep, &tls_in, errstr);
3285 if (rc != OK) return rc;
3286 ctx = state_server.lib_state.lib_ctx;
3288 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
3289 were historically separated by underscores. So that I can use either form in my
3290 tests, and also for general convenience, we turn underscores into hyphens here.
3292 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
3293 for TLS 1.3 . Since we do not call it at present we get the default list:
3294 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
3297 if (state_server.lib_state.pri_string)
3298 { DEBUG(D_tls) debug_printf("TLS: cipher list was preloaded\n"); }
3301 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
3306 normalise_ciphers(&expciphers, tls_require_ciphers);
3307 if ((rc = server_load_ciphers(ctx, &state_server, expciphers, errstr)) != OK)
3312 /* If this is a host for which certificate verification is mandatory or
3313 optional, set up appropriately. */
3315 tls_in.certificate_verified = FALSE;
3317 tls_in.dane_verified = FALSE;
3319 server_verify_callback_called = FALSE;
3321 if (verify_check_host(&tls_verify_hosts) == OK)
3322 server_verify_optional = FALSE;
3323 else if (verify_check_host(&tls_try_verify_hosts) == OK)
3324 server_verify_optional = TRUE;
3330 if (!expand_check(tls_verify_certificates, US"tls_verify_certificates",
3333 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3335 if (state_server.lib_state.cabundle)
3336 { DEBUG(D_tls) debug_printf("TLS: CA bundle for server was preloaded\n"); }
3338 if ((rc = setup_certs(ctx, expcerts, tls_crl, NULL, errstr)) != OK)
3341 if (expcerts && *expcerts)
3342 setup_cert_verify(ctx, server_verify_optional, verify_callback_server);
3346 #ifndef DISABLE_TLS_RESUME
3347 # if OPENSSL_VERSION_NUMBER < 0x30000000L
3348 SSL_CTX_set_tlsext_ticket_key_cb(ctx, ticket_key_callback);
3349 /* despite working, appears to always return failure, so ignoring */
3351 SSL_CTX_set_tlsext_ticket_key_evp_cb(ctx, ticket_key_callback);
3352 /* despite working, appears to always return failure, so ignoring */
3356 #ifdef OPENSSL_HAVE_NUM_TICKETS
3357 # ifndef DISABLE_TLS_RESUME
3358 SSL_CTX_set_num_tickets(ctx, tls_in.host_resumable ? 1 : 0);
3360 SSL_CTX_set_num_tickets(ctx, 0); /* send no TLS1.3 stateful-tickets */
3365 /* Prepare for new connection */
3367 if (!(ssl = SSL_new(ctx)))
3368 return tls_error(US"SSL_new", NULL, NULL, errstr);
3369 state_server.lib_state.lib_ssl = ssl;
3371 /* Warning: we used to SSL_clear(ssl) here, it was removed.
3373 * With the SSL_clear(), we get strange interoperability bugs with
3374 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
3375 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
3377 * The SSL_clear() call is to let an existing SSL* be reused, typically after
3378 * session shutdown. In this case, we have a brand new object and there's no
3379 * obvious reason to immediately clear it. I'm guessing that this was
3380 * originally added because of incomplete initialisation which the clear fixed,
3381 * in some historic release.
3384 /* Set context and tell client to go ahead, except in the case of TLS startup
3385 on connection, where outputting anything now upsets the clients and tends to
3386 make them disconnect. We need to have an explicit fflush() here, to force out
3387 the response. Other smtp_printf() calls do not need it, because in non-TLS
3388 mode, the fflush() happens when smtp_getc() is called. */
3390 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
3391 if (!tls_in.on_connect)
3393 smtp_printf("220 TLS go ahead\r\n", FALSE);
3397 /* Now negotiate the TLS session. We put our own timer on it, since it seems
3398 that the OpenSSL library doesn't. */
3400 SSL_set_wfd(ssl, fileno(smtp_out));
3401 SSL_set_rfd(ssl, fileno(smtp_in));
3402 SSL_set_accept_state(ssl);
3404 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
3407 sigalrm_seen = FALSE;
3408 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3409 rc = SSL_accept(ssl);
3414 int error = SSL_get_error(ssl, rc);
3417 case SSL_ERROR_NONE:
3420 case SSL_ERROR_ZERO_RETURN:
3421 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3422 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
3423 #ifndef DISABLE_EVENT
3424 (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);
3426 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
3429 tls_close(NULL, TLS_NO_SHUTDOWN);
3432 /* Handle genuine errors */
3436 int r = ERR_GET_REASON(ERR_peek_error());
3437 if ( r == SSL_R_WRONG_VERSION_NUMBER
3438 #ifdef SSL_R_VERSION_TOO_LOW
3439 || r == SSL_R_VERSION_TOO_LOW
3441 || r == SSL_R_UNKNOWN_PROTOCOL || r == SSL_R_UNSUPPORTED_PROTOCOL)
3442 s = string_sprintf("(%s)", SSL_get_version(ssl));
3443 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : s, errstr);
3444 #ifndef DISABLE_EVENT
3445 (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);
3451 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
3452 if (error == SSL_ERROR_SYSCALL)
3456 *errstr = US"SSL_accept: TCP connection closed by peer";
3457 #ifndef DISABLE_EVENT
3458 (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);
3462 DEBUG(D_tls) debug_printf(" - syscall %s\n", strerror(errno));
3464 (void) tls_error(US"SSL_accept", NULL,
3465 sigalrm_seen ? US"timed out"
3466 : ERR_peek_error() ? NULL : string_sprintf("ret %d", error),
3468 #ifndef DISABLE_EVENT
3469 (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);
3475 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
3476 ERR_clear_error(); /* Even success can leave errors in the stack. Seen with
3477 anon-authentication ciphersuite negotiated. */
3479 #ifndef DISABLE_TLS_RESUME
3480 if (SSL_session_reused(ssl))
3482 tls_in.resumption |= RESUME_USED;
3483 DEBUG(D_tls) debug_printf("Session reused\n");
3487 #ifdef EXIM_HAVE_ALPN
3488 /* If require-alpn, check server_seen_alpn here. Else abort TLS */
3489 if (!tls_alpn || !*tls_alpn)
3490 { DEBUG(D_tls) debug_printf("TLS: was not watching for ALPN\n"); }
3491 else if (!server_seen_alpn)
3492 if (verify_check_host(&hosts_require_alpn) == OK)
3494 /* We'd like to send a definitive Alert but OpenSSL provides no facility */
3496 tls_error(US"handshake", NULL, US"ALPN required but not negotiated", errstr);
3500 { DEBUG(D_tls) debug_printf("TLS: no ALPN presented in handshake\n"); }
3503 const uschar * name;
3505 SSL_get0_alpn_selected(ssl, &name, &len);
3507 debug_printf("ALPN negotiated: '%.*s'\n", (int)*name, name+1);
3509 debug_printf("ALPN: no protocol negotiated\n");
3514 /* TLS has been set up. Record data for the connection,
3515 adjust the input functions to read via TLS, and initialize things. */
3517 #ifdef SSL_get_extms_support
3518 /*XXX what does this return for tls1.3 ? */
3519 tls_in.ext_master_secret = SSL_get_extms_support(ssl) == 1;
3521 peer_cert(ssl, &tls_in, peerdn, sizeof(peerdn));
3523 tls_in.ver = tlsver_name(ssl);
3524 tls_in.cipher = construct_cipher_name(ssl, tls_in.ver, &tls_in.bits);
3525 tls_in.cipher_stdname = cipher_stdname_ssl(ssl);
3530 if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)))
3531 debug_printf("Shared ciphers: %s\n", buf);
3533 tls_dump_keylog(ssl);
3535 #ifdef EXIM_HAVE_SESSION_TICKET
3537 SSL_SESSION * ss = SSL_get_session(ssl);
3538 if (SSL_SESSION_has_ticket(ss)) /* 1.1.0 */
3539 debug_printf("The session has a ticket, life %lu seconds\n",
3540 SSL_SESSION_get_ticket_lifetime_hint(ss));
3545 /* Record the certificate we presented */
3547 X509 * crt = SSL_get_certificate(ssl);
3548 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
3551 tls_get_channel_binding(ssl, &tls_in, GET_UNTAINTED);
3553 /* Only used by the server-side tls (tls_in), including tls_getc.
3554 Client-side (tls_out) reads (seem to?) go via
3555 smtp_read_response()/ip_recv().
3556 Hence no need to duplicate for _in and _out.
3558 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
3559 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
3560 ssl_xfer_eof = ssl_xfer_error = FALSE;
3562 receive_getc = tls_getc;
3563 receive_getbuf = tls_getbuf;
3564 receive_get_cache = tls_get_cache;
3565 receive_hasc = tls_hasc;
3566 receive_ungetc = tls_ungetc;
3567 receive_feof = tls_feof;
3568 receive_ferror = tls_ferror;
3570 tls_in.active.sock = fileno(smtp_out);
3571 tls_in.active.tls_ctx = NULL; /* not using explicit ctx for server-side */
3579 tls_client_basic_ctx_init(SSL_CTX * ctx,
3580 host_item * host, smtp_transport_options_block * ob, exim_openssl_state_st * state,
3585 /* Back-compatible old behaviour if tls_verify_certificates is set but both
3586 tls_verify_hosts and tls_try_verify_hosts are not set. Check only the specified
3587 host patterns if one of them is set with content. */
3589 if ( ( ( !ob->tls_verify_hosts || !ob->tls_verify_hosts
3590 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3592 && ( !ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts
3593 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3596 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
3598 client_verify_optional = FALSE;
3599 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
3600 client_verify_optional = TRUE;
3606 if (!expand_check(ob->tls_verify_certificates, US"tls_verify_certificates",
3609 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3611 if (state->lib_state.cabundle)
3612 { DEBUG(D_tls) debug_printf("TLS: CA bundle was preloaded\n"); }
3614 if ((rc = setup_certs(ctx, expcerts, ob->tls_crl, host, errstr)) != OK)
3617 if (expcerts && *expcerts)
3618 setup_cert_verify(ctx, client_verify_optional, verify_callback_client);
3621 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
3623 state->verify_cert_hostnames =
3625 string_domain_utf8_to_alabel(host->certname, NULL);
3629 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
3630 state->verify_cert_hostnames);
3638 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
3641 const char * hostnames[2] = { CS host->name, NULL };
3644 if (DANESSL_init(ssl, NULL, hostnames) != 1)
3645 return tls_error(US"hostnames load", host, NULL, errstr);
3647 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
3648 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
3649 ) if (rr->type == T_TLSA && rr->size > 3)
3651 const uschar * p = rr->data;
3652 uint8_t usage, selector, mtype;
3653 const char * mdname;
3657 /* Only DANE-TA(2) and DANE-EE(3) are supported */
3658 if (usage != 2 && usage != 3) continue;
3665 default: continue; /* Only match-types 0, 1, 2 are supported */
3666 case 0: mdname = NULL; break;
3667 case 1: mdname = "sha256"; break;
3668 case 2: mdname = "sha512"; break;
3672 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
3675 return tls_error(US"tlsa load", host, NULL, errstr);
3676 case 0: /* action not taken */
3680 tls_out.tlsa_usage |= 1<<usage;
3686 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
3689 #endif /*SUPPORT_DANE*/
3693 #ifndef DISABLE_TLS_RESUME
3694 /* On the client, get any stashed session for the given IP from hints db
3695 and apply it to the ssl-connection for attempted resumption. */
3698 tls_retrieve_session(tls_support * tlsp, SSL * ssl)
3700 if (tlsp->host_resumable)
3702 const uschar * key = tlsp->resume_index;
3703 dbdata_tls_session * dt;
3705 open_db dbblock, * dbm_file;
3707 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
3709 debug_printf("checking for resumable session for %s\n", tlsp->resume_index);
3710 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3712 if ((dt = dbfn_read_with_length(dbm_file, tlsp->resume_index, &len)))
3714 SSL_SESSION * ss = NULL;
3715 const uschar * sess_asn1 = dt->session;
3717 len -= sizeof(dbdata_tls_session);
3718 if (!(d2i_SSL_SESSION(&ss, &sess_asn1, (long)len)))
3722 ERR_error_string_n(ERR_get_error(),
3723 ssl_errstring, sizeof(ssl_errstring));
3724 debug_printf("decoding session: %s\n", ssl_errstring);
3729 unsigned long lifetime =
3730 #ifdef EXIM_HAVE_SESSION_TICKET
3731 SSL_SESSION_get_ticket_lifetime_hint(ss);
3732 #else /* Use, fairly arbitrilarily, what we as server would */
3733 f.running_in_test_harness ? 6 : ssl_session_timeout;
3735 if (lifetime + dt->time_stamp < time(NULL))
3737 DEBUG(D_tls) debug_printf("session expired\n");
3738 dbfn_delete(dbm_file, tlsp->resume_index);
3740 else if (SSL_set_session(ssl, ss))
3742 DEBUG(D_tls) debug_printf("good session\n");
3743 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
3744 tlsp->verify_override = dt->verify_override;
3745 tlsp->ocsp = dt->ocsp;
3749 ERR_error_string_n(ERR_get_error(),
3750 ssl_errstring, sizeof(ssl_errstring));
3751 debug_printf("applying session to ssl: %s\n", ssl_errstring);
3756 DEBUG(D_tls) debug_printf("no session record\n");
3757 dbfn_close(dbm_file);
3763 /* On the client, save the session for later resumption */
3766 tls_save_session_cb(SSL * ssl, SSL_SESSION * ss)
3768 exim_openssl_state_st * cbinfo = SSL_get_ex_data(ssl, tls_exdata_idx);
3771 DEBUG(D_tls) debug_printf("tls_save_session_cb\n");
3773 if (!cbinfo || !(tlsp = cbinfo->tlsp)->host_resumable) return 0;
3775 # ifdef OPENSSL_HAVE_NUM_TICKETS
3776 if (SSL_SESSION_is_resumable(ss)) /* 1.1.1 */
3779 int len = i2d_SSL_SESSION(ss, NULL);
3780 int dlen = sizeof(dbdata_tls_session) + len;
3781 dbdata_tls_session * dt = store_get(dlen, GET_TAINTED);
3782 uschar * s = dt->session;
3783 open_db dbblock, * dbm_file;
3785 DEBUG(D_tls) debug_printf("session is resumable\n");
3786 tlsp->resumption |= RESUME_SERVER_TICKET; /* server gave us a ticket */
3788 dt->verify_override = tlsp->verify_override;
3789 dt->ocsp = tlsp->ocsp;
3790 (void) i2d_SSL_SESSION(ss, &s); /* s gets bumped to end */
3792 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3794 dbfn_write(dbm_file, tlsp->resume_index, dt, dlen);
3795 dbfn_close(dbm_file);
3796 DEBUG(D_tls) debug_printf("wrote session (len %u) to db\n",
3804 /* Construct a key for session DB lookup, and setup the SSL_CTX for resumption */
3807 tls_client_ctx_resume_prehandshake(
3808 exim_openssl_client_tls_ctx * exim_client_ctx, smtp_connect_args * conn_args,
3809 tls_support * tlsp, smtp_transport_options_block * ob)
3811 tlsp->host_resumable = TRUE;
3812 tls_client_resmption_key(tlsp, conn_args, ob);
3814 SSL_CTX_set_session_cache_mode(exim_client_ctx->ctx,
3815 SSL_SESS_CACHE_CLIENT
3816 | SSL_SESS_CACHE_NO_INTERNAL | SSL_SESS_CACHE_NO_AUTO_CLEAR);
3817 SSL_CTX_sess_set_new_cb(exim_client_ctx->ctx, tls_save_session_cb);
3821 tls_client_ssl_resume_prehandshake(SSL * ssl, tls_support * tlsp,
3822 host_item * host, uschar ** errstr)
3824 if (tlsp->host_resumable)
3827 debug_printf("tls_resumption_hosts overrides openssl_options, enabling tickets\n");
3828 SSL_clear_options(ssl, SSL_OP_NO_TICKET);
3830 tls_exdata_idx = SSL_get_ex_new_index(0, 0, 0, 0, 0);
3831 if (!SSL_set_ex_data(ssl, tls_exdata_idx, client_static_state))
3833 tls_error(US"set ex_data", host, NULL, errstr);
3836 debug_printf("tls_exdata_idx %d cbinfo %p\n", tls_exdata_idx, client_static_state);
3839 tlsp->resumption = RESUME_SUPPORTED;
3840 /* Pick up a previous session, saved on an old ticket */
3841 tls_retrieve_session(tlsp, ssl);
3846 tls_client_resume_posthandshake(exim_openssl_client_tls_ctx * exim_client_ctx,
3849 if (SSL_session_reused(exim_client_ctx->ssl))
3851 DEBUG(D_tls) debug_printf("The session was reused\n");
3852 tlsp->resumption |= RESUME_USED;
3855 #endif /* !DISABLE_TLS_RESUME */
3858 #ifdef EXIM_HAVE_ALPN
3859 /* Expand and convert an Exim list to an ALPN list. False return for fail.
3860 NULL plist return for silent no-ALPN.
3862 Overwite the passed-in list with the expanded version.
3866 tls_alpn_plist(uschar ** tls_alpn, const uschar ** plist, unsigned * plen,
3871 if (!expand_check(*tls_alpn, US"tls_alpn", &exp_alpn, errstr))
3873 *tls_alpn = exp_alpn;
3877 DEBUG(D_tls) debug_printf("Setting TLS ALPN forced to fail, not sending\n");
3882 /* The server implementation only accepts exactly one protocol name
3883 but it's little extra code complexity in the client. */
3885 const uschar * list = exp_alpn;
3886 uschar * p = store_get(Ustrlen(exp_alpn), exp_alpn), * s, * t;
3890 for (t = p; s = string_nextinlist(&list, &sep, NULL, 0); t += len)
3892 *t++ = len = (uschar) Ustrlen(s);
3895 *plist = (*plen = t - p) ? p : NULL;
3899 #endif /* EXIM_HAVE_ALPN */
3902 /*************************************************
3903 * Start a TLS session in a client *
3904 *************************************************/
3906 /* Called from the smtp transport after STARTTLS has been accepted.
3909 cctx connection context
3910 conn_args connection details
3911 cookie datum for randomness; can be NULL
3912 tlsp record details of TLS channel configuration here; must be non-NULL
3913 errstr error string pointer
3915 Returns: TRUE for success with TLS session context set in connection context,
3920 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
3921 void * cookie, tls_support * tlsp, uschar ** errstr)
3923 host_item * host = conn_args->host; /* for msgs and option-tests */
3924 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
3925 smtp_transport_options_block * ob = tb
3926 ? (smtp_transport_options_block *)tb->options_block
3927 : &smtp_transport_option_defaults;
3928 exim_openssl_client_tls_ctx * exim_client_ctx;
3929 uschar * expciphers;
3931 static uschar peerdn[256];
3933 #ifndef DISABLE_OCSP
3934 BOOL request_ocsp = FALSE;
3935 BOOL require_ocsp = FALSE;
3939 store_pool = POOL_PERM;
3940 exim_client_ctx = store_get(sizeof(exim_openssl_client_tls_ctx), GET_UNTAINTED);
3941 exim_client_ctx->corked = NULL;
3945 tlsp->tlsa_usage = 0;
3948 #ifndef DISABLE_OCSP
3950 # ifdef SUPPORT_DANE
3951 /*XXX this should be moved to caller, to be common across gnutls/openssl */
3952 if ( conn_args->dane
3953 && ob->hosts_request_ocsp[0] == '*'
3954 && ob->hosts_request_ocsp[1] == '\0'
3957 /* Unchanged from default. Use a safer one under DANE */
3958 request_ocsp = TRUE;
3959 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
3960 " {= {4}{$tls_out_tlsa_usage}} } "
3966 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK))
3967 request_ocsp = TRUE;
3969 # ifdef SUPPORT_DANE
3973 verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3977 rc = tls_init(host, ob,
3978 #ifndef DISABLE_OCSP
3979 (void *)(long)request_ocsp,
3981 cookie, &client_static_state, tlsp, errstr);
3982 if (rc != OK) return FALSE;
3984 exim_client_ctx->ctx = client_static_state->lib_state.lib_ctx;
3986 tlsp->certificate_verified = FALSE;
3987 client_verify_callback_called = FALSE;
3991 if (conn_args->dane)
3993 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
3994 other failures should be treated as problems. */
3995 if (ob->dane_require_tls_ciphers &&
3996 !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
3997 &expciphers, errstr))
3999 if (expciphers && *expciphers == '\0')
4002 normalise_ciphers(&expciphers, ob->dane_require_tls_ciphers);
4007 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
4008 &expciphers, errstr))
4011 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
4012 are separated by underscores. So that I can use either form in my tests, and
4013 also for general convenience, we turn underscores into hyphens here. */
4015 normalise_ciphers(&expciphers, ob->tls_require_ciphers);
4020 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
4021 if (!SSL_CTX_set_cipher_list(exim_client_ctx->ctx, CS expciphers))
4023 tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
4029 if (conn_args->dane)
4031 SSL_CTX_set_verify(exim_client_ctx->ctx,
4032 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
4033 verify_callback_client_dane);
4035 if (!DANESSL_library_init())
4037 tls_error(US"library init", host, NULL, errstr);
4040 if (DANESSL_CTX_init(exim_client_ctx->ctx) <= 0)
4042 tls_error(US"context init", host, NULL, errstr);
4050 if (tls_client_basic_ctx_init(exim_client_ctx->ctx, host, ob,
4051 client_static_state, errstr) != OK)
4056 if (!expand_check(ob->tls_sni, US"tls_sni", &tlsp->sni, errstr))
4059 { DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n"); }
4060 else if (!Ustrlen(tlsp->sni))
4064 #ifndef EXIM_HAVE_OPENSSL_TLSEXT
4065 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
4073 #ifdef EXIM_HAVE_ALPN
4075 const uschar * plist;
4078 if (!tls_alpn_plist(&ob->tls_alpn, &plist, &plen, errstr))
4081 if (SSL_CTX_set_alpn_protos(exim_client_ctx->ctx, plist, plen) != 0)
4083 tls_error(US"alpn init", host, NULL, errstr);
4087 DEBUG(D_tls) debug_printf("Setting TLS ALPN '%s'\n", ob->tls_alpn);
4090 log_write(0, LOG_MAIN, "ALPN unusable with this OpenSSL library version; ignoring \"%s\"\n",
4094 #ifndef DISABLE_TLS_RESUME
4095 /*XXX have_lbserver: another cmdline arg possibly, for continued-conn, but use
4096 will be very low. */
4098 if (!conn_args->have_lbserver) /* wanted for tls_client_resmption_key() */
4099 { DEBUG(D_tls) debug_printf("resumption not supported on continued-connection\n"); }
4100 else if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
4101 tls_client_ctx_resume_prehandshake(exim_client_ctx, conn_args, tlsp, ob);
4105 if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx)))
4107 tls_error(US"SSL_new", host, NULL, errstr);
4110 SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx));
4111 SSL_set_fd(exim_client_ctx->ssl, cctx->sock);
4112 SSL_set_connect_state(exim_client_ctx->ssl);
4114 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
4117 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tlsp->sni);
4118 SSL_set_tlsext_host_name(exim_client_ctx->ssl, tlsp->sni);
4123 if (conn_args->dane)
4124 if (dane_tlsa_load(exim_client_ctx->ssl, host, &conn_args->tlsa_dnsa, errstr) != OK)
4128 #ifndef DISABLE_OCSP
4129 /* Request certificate status at connection-time. If the server
4130 does OCSP stapling we will get the callback (set in tls_init()) */
4131 # ifdef SUPPORT_DANE
4135 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
4136 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
4138 { /* Re-eval now $tls_out_tlsa_usage is populated. If
4139 this means we avoid the OCSP request, we wasted the setup
4140 cost in tls_init(). */
4141 require_ocsp = verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
4142 request_ocsp = require_ocsp
4143 || verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
4150 SSL_set_tlsext_status_type(exim_client_ctx->ssl, TLSEXT_STATUSTYPE_ocsp);
4151 client_static_state->u_ocsp.client.verify_required = require_ocsp;
4152 tlsp->ocsp = OCSP_NOT_RESP;
4156 #ifndef DISABLE_TLS_RESUME
4157 if (!tls_client_ssl_resume_prehandshake(exim_client_ctx->ssl, tlsp, host,
4162 #ifndef DISABLE_EVENT
4163 client_static_state->event_action = tb ? tb->event_action : NULL;
4166 /* There doesn't seem to be a built-in timeout on connection. */
4168 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
4169 sigalrm_seen = FALSE;
4170 ALARM(ob->command_timeout);
4171 rc = SSL_connect(exim_client_ctx->ssl);
4175 if (conn_args->dane)
4176 DANESSL_cleanup(exim_client_ctx->ssl);
4181 tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, errstr);
4187 debug_printf("SSL_connect succeeded\n");
4188 tls_dump_keylog(exim_client_ctx->ssl);
4191 #ifndef DISABLE_TLS_RESUME
4192 tls_client_resume_posthandshake(exim_client_ctx, tlsp);
4195 #ifdef EXIM_HAVE_ALPN
4196 if (ob->tls_alpn) /* We requested. See what was negotiated. */
4198 const uschar * name;
4201 SSL_get0_alpn_selected(exim_client_ctx->ssl, &name, &len);
4203 { DEBUG(D_tls) debug_printf("ALPN negotiated %u: '%.*s'\n", len, (int)*name, name+1); }
4204 else if (verify_check_given_host(CUSS &ob->hosts_require_alpn, host) == OK)
4206 /* Would like to send a relevant fatal Alert, but OpenSSL has no API */
4207 tls_error(US"handshake", host, US"ALPN required but not negotiated", errstr);
4213 #ifdef SSL_get_extms_support
4214 tlsp->ext_master_secret = SSL_get_extms_support(exim_client_ctx->ssl) == 1;
4216 peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn));
4218 tlsp->ver = tlsver_name(exim_client_ctx->ssl);
4219 tlsp->cipher = construct_cipher_name(exim_client_ctx->ssl, tlsp->ver, &tlsp->bits);
4220 tlsp->cipher_stdname = cipher_stdname_ssl(exim_client_ctx->ssl);
4222 /* Record the certificate we presented */
4224 X509 * crt = SSL_get_certificate(exim_client_ctx->ssl);
4225 tlsp->ourcert = crt ? X509_dup(crt) : NULL;
4228 /*XXX will this work with continued-TLS? */
4229 tls_get_channel_binding(exim_client_ctx->ssl, tlsp, GET_TAINTED);
4231 tlsp->active.sock = cctx->sock;
4232 tlsp->active.tls_ctx = exim_client_ctx;
4233 cctx->tls_ctx = exim_client_ctx;
4242 tls_refill(unsigned lim)
4244 SSL * ssl = state_server.lib_state.lib_ssl;
4248 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
4249 ssl_xfer_buffer, ssl_xfer_buffer_size);
4252 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
4253 inbytes = SSL_read(ssl, CS ssl_xfer_buffer,
4254 MIN(ssl_xfer_buffer_size, lim));
4255 error = SSL_get_error(ssl, inbytes);
4256 if (smtp_receive_timeout > 0) ALARM_CLR(0);
4258 if (had_command_timeout) /* set by signal handler */
4259 smtp_command_timeout_exit(); /* does not return */
4260 if (had_command_sigterm)
4261 smtp_command_sigterm_exit();
4262 if (had_data_timeout)
4263 smtp_data_timeout_exit();
4264 if (had_data_sigint)
4265 smtp_data_sigint_exit();
4267 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
4268 closed down, not that the socket itself has been closed down. Revert to
4269 non-SSL handling. */
4273 case SSL_ERROR_NONE:
4276 case SSL_ERROR_ZERO_RETURN:
4277 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
4279 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
4282 tls_close(NULL, TLS_NO_SHUTDOWN);
4285 /* Handle genuine errors */
4287 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4288 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
4289 ssl_xfer_error = TRUE;
4293 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
4294 DEBUG(D_tls) if (error == SSL_ERROR_SYSCALL)
4295 debug_printf(" - syscall %s\n", strerror(errno));
4296 ssl_xfer_error = TRUE;
4300 #ifndef DISABLE_DKIM
4301 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
4303 ssl_xfer_buffer_hwm = inbytes;
4304 ssl_xfer_buffer_lwm = 0;
4309 /*************************************************
4310 * TLS version of getc *
4311 *************************************************/
4313 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
4314 it refills the buffer via the SSL reading function.
4316 Arguments: lim Maximum amount to read/buffer
4317 Returns: the next character or EOF
4319 Only used by the server-side TLS.
4323 tls_getc(unsigned lim)
4325 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
4326 if (!tls_refill(lim))
4327 return ssl_xfer_error ? EOF : smtp_getc(lim);
4329 /* Something in the buffer; return next uschar */
4331 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
4337 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm;
4341 tls_getbuf(unsigned * len)
4346 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
4347 if (!tls_refill(*len))
4349 if (!ssl_xfer_error) return smtp_getbuf(len);
4354 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
4356 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
4357 ssl_xfer_buffer_lwm += size;
4364 tls_get_cache(unsigned lim)
4366 #ifndef DISABLE_DKIM
4367 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
4368 debug_printf("tls_get_cache\n");
4372 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
4378 tls_could_getc(void)
4380 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm
4381 || SSL_pending(state_server.lib_state.lib_ssl) > 0;
4385 /*************************************************
4386 * Read bytes from TLS channel *
4387 *************************************************/
4391 ct_ctx client context pointer, or NULL for the one global server context
4395 Returns: the number of bytes read
4396 -1 after a failed read, including EOF
4398 Only used by the client-side TLS.
4402 tls_read(void * ct_ctx, uschar *buff, size_t len)
4404 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
4405 : state_server.lib_state.lib_ssl;
4409 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
4410 buff, (unsigned int)len);
4413 inbytes = SSL_read(ssl, CS buff, len);
4414 error = SSL_get_error(ssl, inbytes);
4416 if (error == SSL_ERROR_ZERO_RETURN)
4418 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
4421 else if (error != SSL_ERROR_NONE)
4431 /*************************************************
4432 * Write bytes down TLS channel *
4433 *************************************************/
4437 ct_ctx client context pointer, or NULL for the one global server context
4440 more further data expected soon
4442 Returns: the number of bytes after a successful write,
4443 -1 after a failed write
4445 Used by both server-side and client-side TLS. Calling with len zero and more unset
4446 will flush buffered writes; buff can be null for this case.
4450 tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
4453 int outbytes, error;
4455 ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
4456 : state_server.lib_state.lib_ssl;
4457 static gstring * server_corked = NULL;
4458 gstring ** corkedp = ct_ctx
4459 ? &((exim_openssl_client_tls_ctx *)ct_ctx)->corked : &server_corked;
4460 gstring * corked = *corkedp;
4462 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
4463 buff, (unsigned long)len, more ? ", more" : "");
4465 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
4466 "more" is notified. This hack is only ok if small amounts are involved AND only
4467 one stream does it, in one context (i.e. no store reset). Currently it is used
4468 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only.
4469 We support callouts done by the server process by using a separate client
4470 context for the stashed information. */
4471 /* + if PIPE_COMMAND, banner & ehlo-resp for smmtp-on-connect. Suspect there's
4472 a store reset there, so use POOL_PERM. */
4473 /* + if CHUNKING, cmds EHLO,MAIL,RCPT(s),BDAT */
4477 if (!len) buff = US &error; /* dummy just so that string_catn is ok */
4479 int save_pool = store_pool;
4480 store_pool = POOL_PERM;
4482 corked = string_catn(corked, buff, len);
4484 store_pool = save_pool;
4491 buff = CUS corked->s;
4496 for (int left = len; left > 0;)
4498 DEBUG(D_tls) debug_printf("SSL_write(%p, %p, %d)\n", ssl, buff, left);
4500 outbytes = SSL_write(ssl, CS buff, left);
4501 error = SSL_get_error(ssl, outbytes);
4502 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
4505 case SSL_ERROR_NONE: /* the usual case */
4511 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4512 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
4515 case SSL_ERROR_ZERO_RETURN:
4516 log_write(0, LOG_MAIN, "SSL channel closed on write");
4519 case SSL_ERROR_SYSCALL:
4520 if (ct_ctx || errno != ECONNRESET || !f.smtp_in_quit)
4521 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
4522 sender_fullhost ? sender_fullhost : US"<unknown>",
4524 else if (LOGGING(protocol_detail))
4525 log_write(0, LOG_MAIN, "[%s] after QUIT, client reset TCP before"
4526 " SMTP response and TLS close\n", sender_host_address);
4528 DEBUG(D_tls) debug_printf("[%s] SSL_write: after QUIT,"
4529 " client reset TCP before TLS close\n", sender_host_address);
4533 log_write(0, LOG_MAIN, "SSL_write error %d", error);
4544 ct_ctx client TLS context pointer, or NULL for the one global server context
4548 tls_shutdown_wr(void * ct_ctx)
4550 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4551 SSL ** sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4552 int * fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4555 if (*fdp < 0) return; /* TLS was not active */
4557 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
4559 HDEBUG(D_transport|D_tls|D_acl|D_v) debug_printf_indent(" SMTP(TLS shutdown)>>\n");
4560 rc = SSL_shutdown(*sslp);
4561 if (rc < 0) DEBUG(D_tls)
4563 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4564 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4568 /*************************************************
4569 * Close down a TLS session *
4570 *************************************************/
4572 /* This is also called from within a delivery subprocess forked from the
4573 daemon, to shut down the TLS library, without actually doing a shutdown (which
4574 would tamper with the SSL session in the parent process).
4577 ct_ctx client TLS context pointer, or NULL for the one global server context
4578 do_shutdown 0 no data-flush or TLS close-alert
4579 1 if TLS close-alert is to be sent,
4580 2 if also response to be waited for
4584 Used by both server-side and client-side TLS.
4588 tls_close(void * ct_ctx, int do_shutdown)
4590 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4591 SSL ** sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4592 int * fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4594 if (*fdp < 0) return; /* TLS was not active */
4596 if (do_shutdown > TLS_NO_SHUTDOWN)
4599 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
4600 do_shutdown > TLS_SHUTDOWN_NOWAIT ? " (with response-wait)" : "");
4602 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
4604 if ( ( do_shutdown >= TLS_SHUTDOWN_WONLY
4605 || (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
4607 && do_shutdown > TLS_SHUTDOWN_NOWAIT
4610 #ifdef EXIM_TCP_CORK
4611 (void) setsockopt(*fdp, IPPROTO_TCP, EXIM_TCP_CORK, US &off, sizeof(off));
4614 rc = SSL_shutdown(*sslp); /* wait for response */
4618 if (rc < 0) DEBUG(D_tls)
4620 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4621 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4625 if (!o_ctx) /* server side */
4627 #ifndef DISABLE_OCSP
4628 sk_X509_pop_free(state_server.verify_stack, X509_free);
4629 state_server.verify_stack = NULL;
4632 receive_getc = smtp_getc;
4633 receive_getbuf = smtp_getbuf;
4634 receive_get_cache = smtp_get_cache;
4635 receive_hasc = smtp_hasc;
4636 receive_ungetc = smtp_ungetc;
4637 receive_feof = smtp_feof;
4638 receive_ferror = smtp_ferror;
4639 tls_in.active.tls_ctx = NULL;
4641 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
4652 /*************************************************
4653 * Let tls_require_ciphers be checked at startup *
4654 *************************************************/
4656 /* The tls_require_ciphers option, if set, must be something which the
4659 Returns: NULL on success, or error message
4663 tls_validate_require_cipher(void)
4666 uschar * expciphers, * err;
4670 if (!(tls_require_ciphers && *tls_require_ciphers))
4673 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
4675 return US"failed to expand tls_require_ciphers";
4677 if (!(expciphers && *expciphers))
4680 normalise_ciphers(&expciphers, tls_require_ciphers);
4683 if (lib_ctx_new(&ctx, NULL, &err) == OK)
4686 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
4688 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
4690 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4691 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
4692 expciphers, ssl_errstring);
4703 /*************************************************
4704 * Report the library versions. *
4705 *************************************************/
4707 /* There have historically been some issues with binary compatibility in
4708 OpenSSL libraries; if Exim (like many other applications) is built against
4709 one version of OpenSSL but the run-time linker picks up another version,
4710 it can result in serious failures, including crashing with a SIGSEGV. So
4711 report the version found by the compiler and the run-time version.
4713 Note: some OS vendors backport security fixes without changing the version
4714 number/string, and the version date remains unchanged. The _build_ date
4715 will change, so we can more usefully assist with version diagnosis by also
4716 reporting the build date.
4718 Arguments: string to append to
4723 tls_version_report(gstring * g)
4725 return string_fmt_append(g,
4726 "Library version: OpenSSL: Compile: %s\n"
4729 OPENSSL_VERSION_TEXT,
4730 SSLeay_version(SSLEAY_VERSION),
4731 SSLeay_version(SSLEAY_BUILT_ON));
4732 /* third line is 38 characters for the %s and the line is 73 chars long;
4733 the OpenSSL output includes a "built on: " prefix already. */
4739 /*************************************************
4740 * Random number generation *
4741 *************************************************/
4743 /* Pseudo-random number generation. The result is not expected to be
4744 cryptographically strong but not so weak that someone will shoot themselves
4745 in the foot using it as a nonce in input in some email header scheme or
4746 whatever weirdness they'll twist this into. The result should handle fork()
4747 and avoid repeating sequences. OpenSSL handles that for us.
4751 Returns a random number in range [0, max-1]
4755 vaguely_random_number(int max)
4759 static pid_t pidlast = 0;
4761 uschar smallbuf[sizeof(r)];
4767 if (pidnow != pidlast)
4769 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
4770 is unique for each thread", this doesn't apparently apply across processes,
4771 so our own warning from vaguely_random_number_fallback() applies here too.
4772 Fix per PostgreSQL. */
4778 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
4782 gettimeofday(&r.tv, NULL);
4785 RAND_seed(US (&r), sizeof(r));
4787 /* We're after pseudo-random, not random; if we still don't have enough data
4788 in the internal PRNG then our options are limited. We could sleep and hope
4789 for entropy to come along (prayer technique) but if the system is so depleted
4790 in the first place then something is likely to just keep taking it. Instead,
4791 we'll just take whatever little bit of pseudo-random we can still manage to
4794 needed_len = sizeof(r);
4795 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
4796 asked for a number less than 10. */
4797 for (r = max, i = 0; r; ++i)
4803 #ifdef EXIM_HAVE_RAND_PSEUDO
4804 /* We do not care if crypto-strong */
4805 i = RAND_pseudo_bytes(smallbuf, needed_len);
4807 i = RAND_bytes(smallbuf, needed_len);
4813 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
4814 return vaguely_random_number_fallback(max);
4818 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
4821 /* We don't particularly care about weighted results; if someone wants
4822 smooth distribution and cares enough then they should submit a patch then. */
4829 /*************************************************
4830 * OpenSSL option parse *
4831 *************************************************/
4833 /* Parse one option for tls_openssl_options_parse below
4836 name one option name
4837 value place to store a value for it
4838 Returns success or failure in parsing
4844 tls_openssl_one_option_parse(uschar *name, long *value)
4847 int last = exim_openssl_options_size;
4848 while (last > first)
4850 int middle = (first + last)/2;
4851 int c = Ustrcmp(name, exim_openssl_options[middle].name);
4854 *value = exim_openssl_options[middle].value;
4868 /*************************************************
4869 * OpenSSL option parsing logic *
4870 *************************************************/
4872 /* OpenSSL has a number of compatibility options which an administrator might
4873 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
4874 we look like log_selector.
4877 option_spec the administrator-supplied string of options
4878 results ptr to long storage for the options bitmap
4879 Returns success or failure
4883 tls_openssl_options_parse(uschar *option_spec, long *results)
4886 uschar * exp, * end;
4887 BOOL adding, item_parsed;
4889 /* Server: send no (<= TLS1.2) session tickets */
4890 result = SSL_OP_NO_TICKET;
4892 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
4893 from default because it increases BEAST susceptibility. */
4894 #ifdef SSL_OP_NO_SSLv2
4895 result |= SSL_OP_NO_SSLv2;
4897 #ifdef SSL_OP_NO_SSLv3
4898 result |= SSL_OP_NO_SSLv3;
4900 #ifdef SSL_OP_SINGLE_DH_USE
4901 result |= SSL_OP_SINGLE_DH_USE;
4903 #ifdef SSL_OP_NO_RENEGOTIATION
4904 result |= SSL_OP_NO_RENEGOTIATION;
4913 if (!expand_check(option_spec, US"openssl_options", &exp, &end))
4916 for (uschar * s = exp; *s; /**/)
4918 while (isspace(*s)) ++s;
4921 if (*s != '+' && *s != '-')
4923 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
4924 "+ or - expected but found \"%s\"\n", s);
4927 adding = *s++ == '+';
4928 for (end = s; *end && !isspace(*end); ) end++;
4929 item_parsed = tls_openssl_one_option_parse(string_copyn(s, end-s), &item);
4932 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
4935 DEBUG(D_tls) debug_printf("openssl option, %s %08lx: %08lx (%s)\n",
4936 adding ? "adding to " : "removing from", result, item, s);
4948 #endif /*!MACRO_PREDEF*/
4951 /* End of tls-openssl.c */