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_options(server_sni, SSL_CTX_get_options(ctx));
2214 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(ctx));
2215 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
2216 SSL_CTX_set_tlsext_servername_arg(server_sni, state);
2219 if ( !init_dh(server_sni, state->dhparam, &dummy_errstr)
2220 || !init_ecdh(server_sni, &dummy_errstr)
2224 if ( state->server_cipher_list
2225 && !SSL_CTX_set_cipher_list(server_sni, CS state->server_cipher_list))
2228 #ifndef DISABLE_OCSP
2229 if (state->u_ocsp.server.file)
2231 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
2232 SSL_CTX_set_tlsext_status_arg(server_sni, state);
2238 if ( !expand_check(tls_verify_certificates, US"tls_verify_certificates",
2239 &expcerts, &dummy_errstr)
2240 || (rc = setup_certs(server_sni, expcerts, tls_crl, NULL,
2241 &dummy_errstr)) != OK)
2244 if (expcerts && *expcerts)
2245 setup_cert_verify(server_sni, FALSE, verify_callback_server);
2248 /* do this after setup_certs, because this can require the certs for verifying
2249 OCSP information. */
2250 if ((rc = tls_expand_session_files(server_sni, state, &dummy_errstr)) != OK)
2253 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
2254 SSL_set_SSL_CTX(s, server_sni);
2255 return SSL_TLSEXT_ERR_OK;
2257 bad: return SSL_TLSEXT_ERR_ALERT_FATAL;
2259 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
2264 #ifdef EXIM_HAVE_ALPN
2265 /*************************************************
2266 * Callback to handle ALPN *
2267 *************************************************/
2269 /* Called on server if tls_alpn nonblank after expansion,
2270 when client offers ALPN, after the SNI callback.
2271 If set and not matching the list then we dump the connection */
2274 tls_server_alpn_cb(SSL *ssl, const uschar ** out, uschar * outlen,
2275 const uschar * in, unsigned int inlen, void * arg)
2277 server_seen_alpn = TRUE;
2280 debug_printf("Received TLS ALPN offer:");
2281 for (int pos = 0, siz; pos < inlen; pos += siz+1)
2284 if (pos + 1 + siz > inlen) siz = inlen - pos - 1;
2285 debug_printf(" '%.*s'", siz, in + pos + 1);
2287 debug_printf(". Our list: '%s'\n", tls_alpn);
2290 /* Look for an acceptable ALPN */
2292 if ( inlen > 1 /* at least one name */
2293 && in[0]+1 == inlen /* filling the vector, so exactly one name */
2296 const uschar * list = tls_alpn;
2298 for (uschar * name; name = string_nextinlist(&list, &sep, NULL, 0); )
2299 if (Ustrncmp(in+1, name, in[0]) == 0)
2301 *out = in+1; /* we checked for exactly one, so can just point to it */
2303 return SSL_TLSEXT_ERR_OK; /* use ALPN */
2307 /* More than one name from clilent, or name did not match our list. */
2309 /* This will be fatal to the TLS conn; would be nice to kill TCP also.
2310 Maybe as an option in future; for now leave control to the config (must-tls). */
2312 DEBUG(D_tls) debug_printf("TLS ALPN rejected\n");
2313 return SSL_TLSEXT_ERR_ALERT_FATAL;
2315 #endif /* EXIM_HAVE_ALPN */
2319 #ifndef DISABLE_OCSP
2321 /*************************************************
2322 * Callback to handle OCSP Stapling *
2323 *************************************************/
2325 /* Called when acting as server during the TLS session setup if the client
2326 requests OCSP information with a Certificate Status Request.
2328 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
2334 tls_server_stapling_cb(SSL *s, void *arg)
2336 const exim_openssl_state_st * state = arg;
2337 ocsp_resplist * olist = state->u_ocsp.server.olist;
2338 uschar * response_der; /*XXX blob */
2339 int response_der_len;
2342 debug_printf("Received TLS status request (OCSP stapling); %s response list\n",
2343 olist ? "have" : "lack");
2345 tls_in.ocsp = OCSP_NOT_RESP;
2347 return SSL_TLSEXT_ERR_NOACK;
2349 #ifdef EXIM_HAVE_OPESSL_GET0_SERIAL
2351 const X509 * cert_sent = SSL_get_certificate(s);
2352 const ASN1_INTEGER * cert_serial = X509_get0_serialNumber(cert_sent);
2353 const BIGNUM * cert_bn = ASN1_INTEGER_to_BN(cert_serial, NULL);
2355 for (; olist; olist = olist->next)
2357 OCSP_BASICRESP * bs = OCSP_response_get1_basic(olist->resp);
2358 const OCSP_SINGLERESP * single = OCSP_resp_get0(bs, 0);
2359 const OCSP_CERTID * cid = OCSP_SINGLERESP_get0_id(single);
2360 ASN1_INTEGER * res_cert_serial;
2361 const BIGNUM * resp_bn;
2362 ASN1_OCTET_STRING * res_cert_iNameHash;
2365 (void) OCSP_id_get0_info(&res_cert_iNameHash, NULL, NULL, &res_cert_serial,
2366 (OCSP_CERTID *) cid);
2367 resp_bn = ASN1_INTEGER_to_BN(res_cert_serial, NULL);
2371 debug_printf("cert serial: %s\n", BN_bn2hex(cert_bn));
2372 debug_printf("resp serial: %s\n", BN_bn2hex(resp_bn));
2375 if (BN_cmp(cert_bn, resp_bn) == 0)
2377 DEBUG(D_tls) debug_printf("matched serial for ocsp\n");
2379 /*XXX TODO: check the rest of the list for duplicate matches.
2380 If any, need to also check the Issuer Name hash.
2381 Without this, we will provide the wrong status in the case of
2386 DEBUG(D_tls) debug_printf("not match serial for ocsp\n");
2390 DEBUG(D_tls) debug_printf("failed to find match for ocsp\n");
2391 return SSL_TLSEXT_ERR_NOACK;
2397 DEBUG(D_tls) debug_printf("OpenSSL version too early to support multi-leaf OCSP\n");
2398 return SSL_TLSEXT_ERR_NOACK;
2402 /*XXX could we do the i2d earlier, rather than during the callback? */
2403 response_der = NULL;
2404 response_der_len = i2d_OCSP_RESPONSE(olist->resp, &response_der);
2405 if (response_der_len <= 0)
2406 return SSL_TLSEXT_ERR_NOACK;
2408 SSL_set_tlsext_status_ocsp_resp(state_server.lib_state.lib_ssl,
2409 response_der, response_der_len);
2410 tls_in.ocsp = OCSP_VFIED;
2411 return SSL_TLSEXT_ERR_OK;
2416 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
2418 BIO_printf(bp, "\t%s: ", str);
2419 ASN1_GENERALIZEDTIME_print(bp, time);
2424 tls_client_stapling_cb(SSL * ssl, void * arg)
2426 exim_openssl_state_st * cbinfo = arg;
2427 const unsigned char * p;
2429 OCSP_RESPONSE * rsp;
2430 OCSP_BASICRESP * bs;
2433 DEBUG(D_tls) debug_printf("Received TLS status callback (OCSP stapling):\n");
2434 len = SSL_get_tlsext_status_ocsp_resp(ssl, &p);
2436 { /* Expect this when we requested ocsp but got none */
2437 if (SSL_session_reused(ssl) && tls_out.ocsp == OCSP_VFIED)
2439 DEBUG(D_tls) debug_printf(" null, but resumed; ocsp vfy stored with session is good\n");
2442 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
2443 log_write(0, LOG_MAIN, "Required TLS certificate status not received");
2445 DEBUG(D_tls) debug_printf(" null\n");
2446 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2449 if (!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
2451 tls_out.ocsp = OCSP_FAILED; /*XXX should use tlsp-> to permit concurrent outbound */
2452 if (LOGGING(tls_cipher))
2453 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
2455 DEBUG(D_tls) debug_printf(" parse error\n");
2459 if (!(bs = OCSP_response_get1_basic(rsp)))
2461 tls_out.ocsp = OCSP_FAILED;
2462 if (LOGGING(tls_cipher))
2463 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
2465 DEBUG(D_tls) debug_printf(" error parsing response\n");
2466 OCSP_RESPONSE_free(rsp);
2470 /* We'd check the nonce here if we'd put one in the request. */
2471 /* However that would defeat cacheability on the server so we don't. */
2473 /* This section of code reworked from OpenSSL apps source;
2474 The OpenSSL Project retains copyright:
2475 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
2479 #ifndef EXIM_HAVE_OCSP_RESP_COUNT
2480 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
2483 DEBUG(D_tls) bp = BIO_new(BIO_s_mem());
2485 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
2487 /* Use the chain that verified the server cert to verify the stapled info */
2488 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
2490 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
2491 cbinfo->u_ocsp.client.verify_store, OCSP_NOEXPLICIT)) <= 0)
2492 if (ERR_peek_error())
2494 tls_out.ocsp = OCSP_FAILED;
2495 if (LOGGING(tls_cipher))
2497 const uschar * errstr = CUS ERR_reason_error_string(ERR_peek_error());
2498 static uschar peerdn[256];
2499 X509_NAME_oneline(X509_get_subject_name(SSL_get_peer_certificate(ssl)),
2500 CS peerdn, sizeof(peerdn));
2501 log_write(0, LOG_MAIN,
2502 "[%s] %s Received TLS cert (DN: '%.*s') status response, "
2503 "itself unverifiable: %s",
2504 sender_host_address, sender_host_name,
2505 (int)sizeof(peerdn), peerdn,
2510 BIO_printf(bp, "OCSP response verify failure\n");
2511 ERR_print_errors(bp);
2512 OCSP_RESPONSE_print(bp, rsp, 0);
2517 DEBUG(D_tls) debug_printf("no explicit trust for OCSP signing"
2518 " in the root CA certificate; ignoring\n");
2520 DEBUG(D_tls) debug_printf("OCSP response well-formed and signed OK\n");
2522 /*XXX So we have a good stapled OCSP status. How do we know
2523 it is for the cert of interest? OpenSSL 1.1.0 has a routine
2524 OCSP_resp_find_status() which matches on a cert id, which presumably
2525 we should use. Making an id needs OCSP_cert_id_new(), which takes
2526 issuerName, issuerKey, serialNumber. Are they all in the cert?
2528 For now, carry on blindly accepting the resp. */
2531 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
2532 OCSP_resp_count(bs) - 1;
2534 sk_OCSP_SINGLERESP_num(sresp) - 1;
2538 OCSP_SINGLERESP * single = OCSP_resp_get0(bs, idx);
2540 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
2542 /*XXX so I can see putting a loop in here to handle a rsp with >1 singleresp
2543 - but what happens with a GnuTLS-style input?
2545 we could do with a debug label for each singleresp
2546 - it has a certID with a serialNumber, but I see no API to get that
2548 status = OCSP_single_get0_status(single, &reason, &rev,
2549 &thisupd, &nextupd);
2553 time_print(bp, "This OCSP Update", thisupd);
2554 if (nextupd) time_print(bp, "Next OCSP Update", nextupd);
2556 if (!OCSP_check_validity(thisupd, nextupd,
2557 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
2559 tls_out.ocsp = OCSP_FAILED;
2560 DEBUG(D_tls) ERR_print_errors(bp);
2561 log_write(0, LOG_MAIN, "OCSP dates invalid");
2565 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
2566 OCSP_cert_status_str(status));
2569 case V_OCSP_CERTSTATUS_GOOD:
2570 continue; /* the idx loop */
2571 case V_OCSP_CERTSTATUS_REVOKED:
2572 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
2573 reason != -1 ? "; reason: " : "",
2574 reason != -1 ? OCSP_crl_reason_str(reason) : "");
2575 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
2578 log_write(0, LOG_MAIN,
2579 "Server certificate status unknown, in OCSP stapling");
2587 tls_out.ocsp = OCSP_VFIED;
2591 tls_out.ocsp = OCSP_FAILED;
2592 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2596 int len = (int) BIO_get_mem_data(bp, CSS &s);
2597 if (len > 0) debug_printf("%.*s", len, s);
2602 OCSP_RESPONSE_free(rsp);
2605 #endif /*!DISABLE_OCSP*/
2608 /*************************************************
2609 * Initialize for TLS *
2610 *************************************************/
2611 /* Called from both server and client code, to do preliminary initialization
2612 of the library. We allocate and return a context structure.
2615 host connected host, if client; NULL if server
2616 ob transport options block, if client; NULL if server
2617 ocsp_file file of stapling info (server); flag for require ocsp (client)
2618 addr address if client; NULL if server (for some randomness)
2619 caller_state place to put pointer to allocated state-struct
2620 errstr error string pointer
2622 Returns: OK/DEFER/FAIL
2626 tls_init(host_item * host, smtp_transport_options_block * ob,
2627 #ifndef DISABLE_OCSP
2630 address_item *addr, exim_openssl_state_st ** caller_state,
2635 exim_openssl_state_st * state;
2638 if (host) /* client */
2640 state = store_malloc(sizeof(exim_openssl_state_st));
2641 memset(state, 0, sizeof(*state));
2642 state->certificate = ob->tls_certificate;
2643 state->privatekey = ob->tls_privatekey;
2644 state->is_server = FALSE;
2645 state->dhparam = NULL;
2646 state->lib_state = ob->tls_preload;
2650 state = &state_server;
2651 state->certificate = tls_certificate;
2652 state->privatekey = tls_privatekey;
2653 state->is_server = TRUE;
2654 state->dhparam = tls_dhparam;
2655 state->lib_state = state_server.lib_state;
2661 if (!state->lib_state.pri_string)
2662 state->server_cipher_list = NULL;
2664 #ifndef DISABLE_EVENT
2665 state->event_action = NULL;
2670 /* It turns out that we need to seed the random number generator this early in
2671 order to get the full complement of ciphers to work. It took me roughly a day
2672 of work to discover this by experiment.
2674 On systems that have /dev/urandom, SSL may automatically seed itself from
2675 there. Otherwise, we have to make something up as best we can. Double check
2678 Although we likely called this before, at daemon startup, this is a chance
2679 to mix in further variable info (time, pid) if needed. */
2681 if (!lib_rand_init(addr))
2682 return tls_error(US"RAND_status", host,
2683 US"unable to seed random number generator", errstr);
2685 /* Apply administrator-supplied work-arounds.
2686 Historically we applied just one requested option,
2687 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
2688 moved to an administrator-controlled list of options to specify and
2689 grandfathered in the first one as the default value for "openssl_options".
2691 No OpenSSL version number checks: the options we accept depend upon the
2692 availability of the option value macros from OpenSSL. */
2695 if (!tls_openssl_options_parse(openssl_options, &init_options))
2696 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
2698 /* Create a context.
2699 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
2700 negotiation in the different methods; as far as I can tell, the only
2701 *_{server,client}_method which allows negotiation is SSLv23, which exists even
2702 when OpenSSL is built without SSLv2 support.
2703 By disabling with openssl_options, we can let admins re-enable with the
2706 if (!(ctx = state->lib_state.lib_ctx))
2708 if ((rc = lib_ctx_new(&ctx, host, errstr)) != OK)
2710 state->lib_state.lib_ctx = ctx;
2713 #ifndef DISABLE_TLS_RESUME
2714 tlsp->resumption = RESUME_SUPPORTED;
2718 #ifndef DISABLE_TLS_RESUME
2719 /* Should the server offer session resumption? */
2720 if (!host && verify_check_host(&tls_resumption_hosts) == OK)
2722 DEBUG(D_tls) debug_printf("tls_resumption_hosts overrides openssl_options\n");
2723 init_options &= ~SSL_OP_NO_TICKET;
2724 tlsp->resumption |= RESUME_SERVER_TICKET; /* server will give ticket on request */
2725 tlsp->host_resumable = TRUE;
2729 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
2730 if (!(SSL_CTX_set_options(ctx, init_options)))
2731 return tls_error(string_sprintf(
2732 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
2735 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
2737 /* We'd like to disable session cache unconditionally, but foolish Outlook
2738 Express clients then give up the first TLS connection and make a second one
2739 (which works). Only when there is an IMAP service on the same machine.
2740 Presumably OE is trying to use the cache for A on B. Leave it enabled for
2741 now, until we work out a decent way of presenting control to the config. It
2742 will never be used because we use a new context every time. */
2744 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
2747 /* Initialize with DH parameters if supplied */
2748 /* Initialize ECDH temp key parameter selection */
2752 if (state->lib_state.dh)
2753 { DEBUG(D_tls) debug_printf("TLS: DH params were preloaded\n"); }
2755 if (!init_dh(ctx, state->dhparam, errstr)) return DEFER;
2757 if (state->lib_state.ecdh)
2758 { DEBUG(D_tls) debug_printf("TLS: ECDH curve was preloaded\n"); }
2760 if (!init_ecdh(ctx, errstr)) return DEFER;
2763 /* Set up certificate and key (and perhaps OCSP info) */
2765 if (state->lib_state.conn_certs)
2768 debug_printf("TLS: %s certs were preloaded\n", host ? "client":"server");
2772 #ifndef DISABLE_OCSP
2773 if (!host) /* server */
2775 state->u_ocsp.server.file = ocsp_file;
2776 state->u_ocsp.server.file_expanded = NULL;
2777 state->u_ocsp.server.olist = NULL;
2780 if ((rc = tls_expand_session_files(ctx, state, errstr)) != OK) return rc;
2783 /* If we need to handle SNI or OCSP, do so */
2785 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2786 # ifndef DISABLE_OCSP
2787 if (!(state->verify_stack = sk_X509_new_null()))
2789 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
2794 if (!host) /* server */
2796 # ifndef DISABLE_OCSP
2797 /* We check u_ocsp.server.file, not server.olist, because we care about if
2798 the option exists, not what the current expansion might be, as SNI might
2799 change the certificate and OCSP file in use between now and the time the
2800 callback is invoked. */
2801 if (state->u_ocsp.server.file)
2803 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
2804 SSL_CTX_set_tlsext_status_arg(ctx, state);
2807 /* We always do this, so that $tls_sni is available even if not used in
2809 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
2810 SSL_CTX_set_tlsext_servername_arg(ctx, state);
2812 # ifdef EXIM_HAVE_ALPN
2813 if (tls_alpn && *tls_alpn)
2816 if ( expand_check(tls_alpn, US"tls_alpn", &exp_alpn, errstr)
2817 && *exp_alpn && !isblank(*exp_alpn))
2819 tls_alpn = exp_alpn; /* subprocess so ok to overwrite */
2820 SSL_CTX_set_alpn_select_cb(ctx, tls_server_alpn_cb, state);
2827 # ifndef DISABLE_OCSP
2829 if(ocsp_file) /* wanting stapling */
2831 if (!(state->u_ocsp.client.verify_store = X509_STORE_new()))
2833 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
2836 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
2837 SSL_CTX_set_tlsext_status_arg(ctx, state);
2842 state->verify_cert_hostnames = NULL;
2844 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
2845 /* Set up the RSA callback */
2846 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
2849 /* Finally, set the session cache timeout, and we are done.
2850 The period appears to be also used for (server-generated) session tickets */
2852 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
2853 DEBUG(D_tls) debug_printf("Initialized TLS\n");
2855 *caller_state = state;
2863 /*************************************************
2864 * Get name of cipher in use *
2865 *************************************************/
2868 Argument: pointer to an SSL structure for the connection
2869 pointer to number of bits for cipher
2870 Returns: pointer to allocated string in perm-pool
2874 construct_cipher_name(SSL * ssl, const uschar * ver, int * bits)
2876 int pool = store_pool;
2877 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
2878 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
2879 the accessor functions use const in the prototype. */
2881 const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
2884 SSL_CIPHER_get_bits(c, bits);
2886 store_pool = POOL_PERM;
2887 s = string_sprintf("%s:%s:%u", ver, SSL_CIPHER_get_name(c), *bits);
2889 DEBUG(D_tls) debug_printf("Cipher: %s\n", s);
2894 /* Get IETF-standard name for ciphersuite.
2895 Argument: pointer to an SSL structure for the connection
2896 Returns: pointer to string
2899 static const uschar *
2900 cipher_stdname_ssl(SSL * ssl)
2902 #ifdef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
2903 return CUS SSL_CIPHER_standard_name(SSL_get_current_cipher(ssl));
2905 ushort id = 0xffff & SSL_CIPHER_get_id(SSL_get_current_cipher(ssl));
2906 return cipher_stdname(id >> 8, id & 0xff);
2911 static const uschar *
2912 tlsver_name(SSL * ssl)
2915 int pool = store_pool;
2917 store_pool = POOL_PERM;
2918 s = string_copy(US SSL_get_version(ssl));
2920 if ((p = Ustrchr(s, 'v'))) /* TLSv1.2 -> TLS1.2 */
2921 for (;; p++) if (!(*p = p[1])) break;
2927 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned siz)
2929 /*XXX we might consider a list-of-certs variable for the cert chain.
2930 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
2931 in list-handling functions, also consider the difference between the entire
2932 chain and the elements sent by the peer. */
2934 tlsp->peerdn = NULL;
2936 /* Will have already noted peercert on a verify fail; possibly not the leaf */
2937 if (!tlsp->peercert)
2938 tlsp->peercert = SSL_get_peer_certificate(ssl);
2939 /* Beware anonymous ciphers which lead to server_cert being NULL */
2941 if (!X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, siz))
2942 { DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n"); }
2945 int oldpool = store_pool;
2947 peerdn[siz-1] = '\0'; /* paranoia */
2948 store_pool = POOL_PERM;
2949 tlsp->peerdn = string_copy(peerdn);
2950 store_pool = oldpool;
2952 /* We used to set CV in the cert-verify callbacks (either plain or dane)
2953 but they don't get called on session-resumption. So use the official
2954 interface, which uses the resumed value. Unfortunately this claims verified
2955 when it actually failed but we're in try-verify mode, due to us wanting the
2956 knowlege that it failed so needing to have the callback and forcing a
2957 permissive return. If we don't force it, the TLS startup is failed.
2958 The extra bit of information is set in verify_override in the cb, stashed
2959 for resumption next to the TLS session, and used here. */
2961 if (!tlsp->verify_override)
2962 tlsp->certificate_verified =
2964 tlsp->dane_verified ||
2966 SSL_get_verify_result(ssl) == X509_V_OK;
2974 /*************************************************
2975 * Set up for verifying certificates *
2976 *************************************************/
2978 #ifndef DISABLE_OCSP
2979 /* Load certs from file, return TRUE on success */
2982 chain_from_pem_file(const uschar * file, STACK_OF(X509) ** vp)
2985 STACK_OF(X509) * verify_stack = *vp;
2988 while (sk_X509_num(verify_stack) > 0)
2989 X509_free(sk_X509_pop(verify_stack));
2991 verify_stack = sk_X509_new_null();
2993 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
2994 for (X509 * x; x = PEM_read_bio_X509(bp, NULL, 0, NULL); )
2995 sk_X509_push(verify_stack, x);
3004 /* Called by both client and server startup; on the server possibly
3005 repeated after a Server Name Indication.
3008 sctx SSL_CTX* to initialise
3009 certs certs file, expanded
3010 crl CRL file or NULL
3011 host NULL in a server; the remote host in a client
3012 errstr error string pointer
3014 Returns: OK/DEFER/FAIL
3018 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host,
3021 uschar *expcerts, *expcrl;
3023 if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
3025 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3027 if (expcerts && *expcerts)
3029 /* Tell the library to use its compiled-in location for the system default
3030 CA bundle. Then add the ones specified in the config, if any. */
3032 if (!SSL_CTX_set_default_verify_paths(sctx))
3033 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
3035 if (Ustrcmp(expcerts, "system") != 0 && Ustrncmp(expcerts, "system,", 7) != 0)
3037 struct stat statbuf;
3039 if (Ustat(expcerts, &statbuf) < 0)
3041 log_write(0, LOG_MAIN|LOG_PANIC,
3042 "failed to stat %s for certificates", expcerts);
3048 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
3049 { file = NULL; dir = expcerts; }
3052 STACK_OF(X509) * verify_stack =
3053 #ifndef DISABLE_OCSP
3054 !host ? state_server.verify_stack :
3057 STACK_OF(X509) ** vp = &verify_stack;
3059 file = expcerts; dir = NULL;
3060 #ifndef DISABLE_OCSP
3061 /* In the server if we will be offering an OCSP proof, load chain from
3062 file for verifying the OCSP proof at load time. */
3064 /*XXX Glitch! The file here is tls_verify_certs: the chain for verifying the client cert.
3065 This is inconsistent with the need to verify the OCSP proof of the server cert.
3068 && statbuf.st_size > 0
3069 && state_server.u_ocsp.server.file
3070 && !chain_from_pem_file(file, vp)
3073 log_write(0, LOG_MAIN|LOG_PANIC,
3074 "failed to load cert chain from %s", file);
3080 /* If a certificate file is empty, the load function fails with an
3081 unhelpful error message. If we skip it, we get the correct behaviour (no
3082 certificates are recognized, but the error message is still misleading (it
3083 says no certificate was supplied). But this is better. */
3085 if ( (!file || statbuf.st_size > 0)
3086 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
3087 return tls_error(US"SSL_CTX_load_verify_locations",
3088 host, NULL, errstr);
3090 /* On the server load the list of CAs for which we will accept certs, for
3091 sending to the client. This is only for the one-file
3092 tls_verify_certificates variant.
3093 If a list isn't loaded into the server, but some verify locations are set,
3094 the server end appears to make a wildcard request for client certs.
3095 Meanwhile, the client library as default behaviour *ignores* the list
3096 we send over the wire - see man SSL_CTX_set_client_cert_cb.
3097 Because of this, and that the dir variant is likely only used for
3098 the public-CA bundle (not for a private CA), not worth fixing. */
3102 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
3103 int i = sk_X509_NAME_num(names);
3105 if (!host) SSL_CTX_set_client_CA_list(sctx, names);
3106 DEBUG(D_tls) debug_printf("Added %d additional certificate authorit%s\n",
3107 i, i>1 ? "ies":"y");
3111 debug_printf("Added dir for additional certificate authorities\n");
3115 /* Handle a certificate revocation list. */
3117 #if OPENSSL_VERSION_NUMBER > 0x00907000L
3119 /* This bit of code is now the version supplied by Lars Mainka. (I have
3120 merely reformatted it into the Exim code style.)
3122 "From here I changed the code to add support for multiple crl's
3123 in pem format in one file or to support hashed directory entries in
3124 pem format instead of a file. This method now uses the library function
3125 X509_STORE_load_locations to add the CRL location to the SSL context.
3126 OpenSSL will then handle the verify against CA certs and CRLs by
3127 itself in the verify callback." */
3129 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
3130 if (expcrl && *expcrl)
3132 struct stat statbufcrl;
3133 if (Ustat(expcrl, &statbufcrl) < 0)
3135 log_write(0, LOG_MAIN|LOG_PANIC,
3136 "failed to stat %s for certificates revocation lists", expcrl);
3141 /* is it a file or directory? */
3143 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
3144 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
3148 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
3154 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
3156 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
3157 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
3159 /* setting the flags to check against the complete crl chain */
3161 X509_STORE_set_flags(cvstore,
3162 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
3166 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
3175 tls_dump_keylog(SSL * ssl)
3177 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3178 BIO * bp = BIO_new(BIO_s_mem());
3181 SSL_SESSION_print_keylog(bp, SSL_get_session(ssl));
3182 len = (int) BIO_get_mem_data(bp, CSS &s);
3183 if (len > 0) debug_printf("%.*s", len, s);
3189 /* Channel-binding info for authenticators
3190 See description in https://paquier.xyz/postgresql-2/channel-binding-openssl/
3195 tls_get_channel_binding(SSL * ssl, tls_support * tlsp, const void * taintval)
3200 #ifdef EXIM_HAVE_EXPORT_CHNL_BNGNG
3201 if (SSL_version(ssl) > TLS1_2_VERSION)
3203 /* It's not documented by OpenSSL how big the output buffer must be.
3204 The OpenSSL testcases use 80 bytes but don't say why. The GnuTLS impl only
3205 serves out 32B. RFC 9266 says it is 32B.
3206 Interop fails unless we use the same each end. */
3209 tlsp->channelbind_exporter = TRUE;
3210 taintval = GET_UNTAINTED;
3211 if (SSL_export_keying_material(ssl,
3212 s = store_get((int)len, taintval), len,
3213 "EXPORTER-Channel-Binding", (size_t) 24,
3220 len = SSL_get_peer_finished(ssl, &c, 0);
3221 len = SSL_get_peer_finished(ssl, s = store_get((int)len, taintval), len);
3226 int old_pool = store_pool;
3227 store_pool = POOL_PERM;
3228 tlsp->channelbinding = b64encode_taint(CUS s, (int)len, taintval);
3229 store_pool = old_pool;
3230 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage %p %p\n", tlsp->channelbinding, tlsp);
3235 /*************************************************
3236 * Start a TLS session in a server *
3237 *************************************************/
3238 /* This is called when Exim is running as a server, after having received
3239 the STARTTLS command. It must respond to that command, and then negotiate
3243 errstr pointer to error message
3245 Returns: OK on success
3246 DEFER for errors before the start of the negotiation
3247 FAIL for errors during the negotiation; the server can't
3252 tls_server_start(uschar ** errstr)
3255 uschar * expciphers;
3256 exim_openssl_state_st * dummy_statep;
3259 static uschar peerdn[256];
3261 /* Check for previous activation */
3263 if (tls_in.active.sock >= 0)
3265 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
3266 smtp_printf("554 Already in TLS\r\n", FALSE);
3270 /* Initialize the SSL library. If it fails, it will already have logged
3273 rc = tls_init(NULL, NULL,
3274 #ifndef DISABLE_OCSP
3277 NULL, &dummy_statep, &tls_in, errstr);
3278 if (rc != OK) return rc;
3279 ctx = state_server.lib_state.lib_ctx;
3281 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
3282 were historically separated by underscores. So that I can use either form in my
3283 tests, and also for general convenience, we turn underscores into hyphens here.
3285 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
3286 for TLS 1.3 . Since we do not call it at present we get the default list:
3287 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
3290 if (state_server.lib_state.pri_string)
3291 { DEBUG(D_tls) debug_printf("TLS: cipher list was preloaded\n"); }
3294 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
3299 normalise_ciphers(&expciphers, tls_require_ciphers);
3300 if ((rc = server_load_ciphers(ctx, &state_server, expciphers, errstr)) != OK)
3305 /* If this is a host for which certificate verification is mandatory or
3306 optional, set up appropriately. */
3308 tls_in.certificate_verified = FALSE;
3310 tls_in.dane_verified = FALSE;
3312 server_verify_callback_called = FALSE;
3314 if (verify_check_host(&tls_verify_hosts) == OK)
3315 server_verify_optional = FALSE;
3316 else if (verify_check_host(&tls_try_verify_hosts) == OK)
3317 server_verify_optional = TRUE;
3323 if (!expand_check(tls_verify_certificates, US"tls_verify_certificates",
3326 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3328 if (state_server.lib_state.cabundle)
3329 { DEBUG(D_tls) debug_printf("TLS: CA bundle for server was preloaded\n"); }
3331 if ((rc = setup_certs(ctx, expcerts, tls_crl, NULL, errstr)) != OK)
3334 if (expcerts && *expcerts)
3335 setup_cert_verify(ctx, server_verify_optional, verify_callback_server);
3339 #ifndef DISABLE_TLS_RESUME
3340 # if OPENSSL_VERSION_NUMBER < 0x30000000L
3341 SSL_CTX_set_tlsext_ticket_key_cb(ctx, ticket_key_callback);
3342 /* despite working, appears to always return failure, so ignoring */
3344 SSL_CTX_set_tlsext_ticket_key_evp_cb(ctx, ticket_key_callback);
3345 /* despite working, appears to always return failure, so ignoring */
3349 #ifdef OPENSSL_HAVE_NUM_TICKETS
3350 # ifndef DISABLE_TLS_RESUME
3351 SSL_CTX_set_num_tickets(ctx, tls_in.host_resumable ? 1 : 0);
3353 SSL_CTX_set_num_tickets(ctx, 0); /* send no TLS1.3 stateful-tickets */
3358 /* Prepare for new connection */
3360 if (!(ssl = SSL_new(ctx)))
3361 return tls_error(US"SSL_new", NULL, NULL, errstr);
3362 state_server.lib_state.lib_ssl = ssl;
3364 /* Warning: we used to SSL_clear(ssl) here, it was removed.
3366 * With the SSL_clear(), we get strange interoperability bugs with
3367 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
3368 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
3370 * The SSL_clear() call is to let an existing SSL* be reused, typically after
3371 * session shutdown. In this case, we have a brand new object and there's no
3372 * obvious reason to immediately clear it. I'm guessing that this was
3373 * originally added because of incomplete initialisation which the clear fixed,
3374 * in some historic release.
3377 /* Set context and tell client to go ahead, except in the case of TLS startup
3378 on connection, where outputting anything now upsets the clients and tends to
3379 make them disconnect. We need to have an explicit fflush() here, to force out
3380 the response. Other smtp_printf() calls do not need it, because in non-TLS
3381 mode, the fflush() happens when smtp_getc() is called. */
3383 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
3384 if (!tls_in.on_connect)
3386 smtp_printf("220 TLS go ahead\r\n", FALSE);
3390 /* Now negotiate the TLS session. We put our own timer on it, since it seems
3391 that the OpenSSL library doesn't. */
3393 SSL_set_wfd(ssl, fileno(smtp_out));
3394 SSL_set_rfd(ssl, fileno(smtp_in));
3395 SSL_set_accept_state(ssl);
3397 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
3400 sigalrm_seen = FALSE;
3401 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3402 rc = SSL_accept(ssl);
3407 int error = SSL_get_error(ssl, rc);
3410 case SSL_ERROR_NONE:
3413 case SSL_ERROR_ZERO_RETURN:
3414 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3415 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
3416 #ifndef DISABLE_EVENT
3417 (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);
3419 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
3422 tls_close(NULL, TLS_NO_SHUTDOWN);
3425 /* Handle genuine errors */
3429 int r = ERR_GET_REASON(ERR_peek_error());
3430 if ( r == SSL_R_WRONG_VERSION_NUMBER
3431 #ifdef SSL_R_VERSION_TOO_LOW
3432 || r == SSL_R_VERSION_TOO_LOW
3434 || r == SSL_R_UNKNOWN_PROTOCOL || r == SSL_R_UNSUPPORTED_PROTOCOL)
3435 s = string_sprintf("(%s)", SSL_get_version(ssl));
3436 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : s, errstr);
3437 #ifndef DISABLE_EVENT
3438 (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);
3444 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
3445 if (error == SSL_ERROR_SYSCALL)
3449 *errstr = US"SSL_accept: TCP connection closed by peer";
3450 #ifndef DISABLE_EVENT
3451 (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);
3455 DEBUG(D_tls) debug_printf(" - syscall %s\n", strerror(errno));
3457 (void) tls_error(US"SSL_accept", NULL,
3458 sigalrm_seen ? US"timed out"
3459 : ERR_peek_error() ? NULL : string_sprintf("ret %d", error),
3461 #ifndef DISABLE_EVENT
3462 (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);
3468 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
3469 ERR_clear_error(); /* Even success can leave errors in the stack. Seen with
3470 anon-authentication ciphersuite negotiated. */
3472 #ifndef DISABLE_TLS_RESUME
3473 if (SSL_session_reused(ssl))
3475 tls_in.resumption |= RESUME_USED;
3476 DEBUG(D_tls) debug_printf("Session reused\n");
3480 #ifdef EXIM_HAVE_ALPN
3481 /* If require-alpn, check server_seen_alpn here. Else abort TLS */
3482 if (!tls_alpn || !*tls_alpn)
3483 { DEBUG(D_tls) debug_printf("TLS: was not watching for ALPN\n"); }
3484 else if (!server_seen_alpn)
3485 if (verify_check_host(&hosts_require_alpn) == OK)
3487 /* We'd like to send a definitive Alert but OpenSSL provides no facility */
3489 tls_error(US"handshake", NULL, US"ALPN required but not negotiated", errstr);
3493 { DEBUG(D_tls) debug_printf("TLS: no ALPN presented in handshake\n"); }
3496 const uschar * name;
3498 SSL_get0_alpn_selected(ssl, &name, &len);
3500 debug_printf("ALPN negotiated: '%.*s'\n", (int)*name, name+1);
3502 debug_printf("ALPN: no protocol negotiated\n");
3507 /* TLS has been set up. Record data for the connection,
3508 adjust the input functions to read via TLS, and initialize things. */
3510 #ifdef SSL_get_extms_support
3511 /*XXX what does this return for tls1.3 ? */
3512 tls_in.ext_master_secret = SSL_get_extms_support(ssl) == 1;
3514 peer_cert(ssl, &tls_in, peerdn, sizeof(peerdn));
3516 tls_in.ver = tlsver_name(ssl);
3517 tls_in.cipher = construct_cipher_name(ssl, tls_in.ver, &tls_in.bits);
3518 tls_in.cipher_stdname = cipher_stdname_ssl(ssl);
3523 if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)))
3524 debug_printf("Shared ciphers: %s\n", buf);
3526 tls_dump_keylog(ssl);
3528 #ifdef EXIM_HAVE_SESSION_TICKET
3530 SSL_SESSION * ss = SSL_get_session(ssl);
3531 if (SSL_SESSION_has_ticket(ss)) /* 1.1.0 */
3532 debug_printf("The session has a ticket, life %lu seconds\n",
3533 SSL_SESSION_get_ticket_lifetime_hint(ss));
3538 /* Record the certificate we presented */
3540 X509 * crt = SSL_get_certificate(ssl);
3541 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
3544 tls_get_channel_binding(ssl, &tls_in, GET_UNTAINTED);
3546 /* Only used by the server-side tls (tls_in), including tls_getc.
3547 Client-side (tls_out) reads (seem to?) go via
3548 smtp_read_response()/ip_recv().
3549 Hence no need to duplicate for _in and _out.
3551 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
3552 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
3553 ssl_xfer_eof = ssl_xfer_error = FALSE;
3555 receive_getc = tls_getc;
3556 receive_getbuf = tls_getbuf;
3557 receive_get_cache = tls_get_cache;
3558 receive_hasc = tls_hasc;
3559 receive_ungetc = tls_ungetc;
3560 receive_feof = tls_feof;
3561 receive_ferror = tls_ferror;
3563 tls_in.active.sock = fileno(smtp_out);
3564 tls_in.active.tls_ctx = NULL; /* not using explicit ctx for server-side */
3572 tls_client_basic_ctx_init(SSL_CTX * ctx,
3573 host_item * host, smtp_transport_options_block * ob, exim_openssl_state_st * state,
3578 /* Back-compatible old behaviour if tls_verify_certificates is set but both
3579 tls_verify_hosts and tls_try_verify_hosts are not set. Check only the specified
3580 host patterns if one of them is set with content. */
3582 if ( ( ( !ob->tls_verify_hosts || !ob->tls_verify_hosts
3583 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3585 && ( !ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts
3586 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3589 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
3591 client_verify_optional = FALSE;
3592 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
3593 client_verify_optional = TRUE;
3599 if (!expand_check(ob->tls_verify_certificates, US"tls_verify_certificates",
3602 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3604 if (state->lib_state.cabundle)
3605 { DEBUG(D_tls) debug_printf("TLS: CA bundle was preloaded\n"); }
3607 if ((rc = setup_certs(ctx, expcerts, ob->tls_crl, host, errstr)) != OK)
3610 if (expcerts && *expcerts)
3611 setup_cert_verify(ctx, client_verify_optional, verify_callback_client);
3614 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
3616 state->verify_cert_hostnames =
3618 string_domain_utf8_to_alabel(host->certname, NULL);
3622 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
3623 state->verify_cert_hostnames);
3631 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
3634 const char * hostnames[2] = { CS host->name, NULL };
3637 if (DANESSL_init(ssl, NULL, hostnames) != 1)
3638 return tls_error(US"hostnames load", host, NULL, errstr);
3640 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
3641 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
3642 ) if (rr->type == T_TLSA && rr->size > 3)
3644 const uschar * p = rr->data;
3645 uint8_t usage, selector, mtype;
3646 const char * mdname;
3650 /* Only DANE-TA(2) and DANE-EE(3) are supported */
3651 if (usage != 2 && usage != 3) continue;
3658 default: continue; /* Only match-types 0, 1, 2 are supported */
3659 case 0: mdname = NULL; break;
3660 case 1: mdname = "sha256"; break;
3661 case 2: mdname = "sha512"; break;
3665 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
3668 return tls_error(US"tlsa load", host, NULL, errstr);
3669 case 0: /* action not taken */
3673 tls_out.tlsa_usage |= 1<<usage;
3679 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
3682 #endif /*SUPPORT_DANE*/
3686 #ifndef DISABLE_TLS_RESUME
3687 /* On the client, get any stashed session for the given IP from hints db
3688 and apply it to the ssl-connection for attempted resumption. */
3691 tls_retrieve_session(tls_support * tlsp, SSL * ssl)
3693 if (tlsp->host_resumable)
3695 const uschar * key = tlsp->resume_index;
3696 dbdata_tls_session * dt;
3698 open_db dbblock, * dbm_file;
3700 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
3702 debug_printf("checking for resumable session for %s\n", tlsp->resume_index);
3703 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3705 if ((dt = dbfn_read_with_length(dbm_file, tlsp->resume_index, &len)))
3707 SSL_SESSION * ss = NULL;
3708 const uschar * sess_asn1 = dt->session;
3710 len -= sizeof(dbdata_tls_session);
3711 if (!(d2i_SSL_SESSION(&ss, &sess_asn1, (long)len)))
3715 ERR_error_string_n(ERR_get_error(),
3716 ssl_errstring, sizeof(ssl_errstring));
3717 debug_printf("decoding session: %s\n", ssl_errstring);
3722 unsigned long lifetime =
3723 #ifdef EXIM_HAVE_SESSION_TICKET
3724 SSL_SESSION_get_ticket_lifetime_hint(ss);
3725 #else /* Use, fairly arbitrilarily, what we as server would */
3726 f.running_in_test_harness ? 6 : ssl_session_timeout;
3728 if (lifetime + dt->time_stamp < time(NULL))
3730 DEBUG(D_tls) debug_printf("session expired\n");
3731 dbfn_delete(dbm_file, tlsp->resume_index);
3733 else if (SSL_set_session(ssl, ss))
3735 DEBUG(D_tls) debug_printf("good session\n");
3736 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
3737 tlsp->verify_override = dt->verify_override;
3738 tlsp->ocsp = dt->ocsp;
3742 ERR_error_string_n(ERR_get_error(),
3743 ssl_errstring, sizeof(ssl_errstring));
3744 debug_printf("applying session to ssl: %s\n", ssl_errstring);
3749 DEBUG(D_tls) debug_printf("no session record\n");
3750 dbfn_close(dbm_file);
3756 /* On the client, save the session for later resumption */
3759 tls_save_session_cb(SSL * ssl, SSL_SESSION * ss)
3761 exim_openssl_state_st * cbinfo = SSL_get_ex_data(ssl, tls_exdata_idx);
3764 DEBUG(D_tls) debug_printf("tls_save_session_cb\n");
3766 if (!cbinfo || !(tlsp = cbinfo->tlsp)->host_resumable) return 0;
3768 # ifdef OPENSSL_HAVE_NUM_TICKETS
3769 if (SSL_SESSION_is_resumable(ss)) /* 1.1.1 */
3772 int len = i2d_SSL_SESSION(ss, NULL);
3773 int dlen = sizeof(dbdata_tls_session) + len;
3774 dbdata_tls_session * dt = store_get(dlen, GET_TAINTED);
3775 uschar * s = dt->session;
3776 open_db dbblock, * dbm_file;
3778 DEBUG(D_tls) debug_printf("session is resumable\n");
3779 tlsp->resumption |= RESUME_SERVER_TICKET; /* server gave us a ticket */
3781 dt->verify_override = tlsp->verify_override;
3782 dt->ocsp = tlsp->ocsp;
3783 (void) i2d_SSL_SESSION(ss, &s); /* s gets bumped to end */
3785 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3787 dbfn_write(dbm_file, tlsp->resume_index, dt, dlen);
3788 dbfn_close(dbm_file);
3789 DEBUG(D_tls) debug_printf("wrote session (len %u) to db\n",
3797 /* Construct a key for session DB lookup, and setup the SSL_CTX for resumption */
3800 tls_client_ctx_resume_prehandshake(
3801 exim_openssl_client_tls_ctx * exim_client_ctx, smtp_connect_args * conn_args,
3802 tls_support * tlsp, smtp_transport_options_block * ob)
3804 tlsp->host_resumable = TRUE;
3805 tls_client_resmption_key(tlsp, conn_args, ob);
3807 SSL_CTX_set_session_cache_mode(exim_client_ctx->ctx,
3808 SSL_SESS_CACHE_CLIENT
3809 | SSL_SESS_CACHE_NO_INTERNAL | SSL_SESS_CACHE_NO_AUTO_CLEAR);
3810 SSL_CTX_sess_set_new_cb(exim_client_ctx->ctx, tls_save_session_cb);
3814 tls_client_ssl_resume_prehandshake(SSL * ssl, tls_support * tlsp,
3815 host_item * host, uschar ** errstr)
3817 if (tlsp->host_resumable)
3820 debug_printf("tls_resumption_hosts overrides openssl_options, enabling tickets\n");
3821 SSL_clear_options(ssl, SSL_OP_NO_TICKET);
3823 tls_exdata_idx = SSL_get_ex_new_index(0, 0, 0, 0, 0);
3824 if (!SSL_set_ex_data(ssl, tls_exdata_idx, client_static_state))
3826 tls_error(US"set ex_data", host, NULL, errstr);
3829 debug_printf("tls_exdata_idx %d cbinfo %p\n", tls_exdata_idx, client_static_state);
3832 tlsp->resumption = RESUME_SUPPORTED;
3833 /* Pick up a previous session, saved on an old ticket */
3834 tls_retrieve_session(tlsp, ssl);
3839 tls_client_resume_posthandshake(exim_openssl_client_tls_ctx * exim_client_ctx,
3842 if (SSL_session_reused(exim_client_ctx->ssl))
3844 DEBUG(D_tls) debug_printf("The session was reused\n");
3845 tlsp->resumption |= RESUME_USED;
3848 #endif /* !DISABLE_TLS_RESUME */
3851 #ifdef EXIM_HAVE_ALPN
3852 /* Expand and convert an Exim list to an ALPN list. False return for fail.
3853 NULL plist return for silent no-ALPN.
3855 Overwite the passed-in list with the expanded version.
3859 tls_alpn_plist(uschar ** tls_alpn, const uschar ** plist, unsigned * plen,
3864 if (!expand_check(*tls_alpn, US"tls_alpn", &exp_alpn, errstr))
3866 *tls_alpn = exp_alpn;
3870 DEBUG(D_tls) debug_printf("Setting TLS ALPN forced to fail, not sending\n");
3875 /* The server implementation only accepts exactly one protocol name
3876 but it's little extra code complexity in the client. */
3878 const uschar * list = exp_alpn;
3879 uschar * p = store_get(Ustrlen(exp_alpn), exp_alpn), * s, * t;
3883 for (t = p; s = string_nextinlist(&list, &sep, NULL, 0); t += len)
3885 *t++ = len = (uschar) Ustrlen(s);
3888 *plist = (*plen = t - p) ? p : NULL;
3892 #endif /* EXIM_HAVE_ALPN */
3895 /*************************************************
3896 * Start a TLS session in a client *
3897 *************************************************/
3899 /* Called from the smtp transport after STARTTLS has been accepted.
3902 cctx connection context
3903 conn_args connection details
3904 cookie datum for randomness; can be NULL
3905 tlsp record details of TLS channel configuration here; must be non-NULL
3906 errstr error string pointer
3908 Returns: TRUE for success with TLS session context set in connection context,
3913 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
3914 void * cookie, tls_support * tlsp, uschar ** errstr)
3916 host_item * host = conn_args->host; /* for msgs and option-tests */
3917 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
3918 smtp_transport_options_block * ob = tb
3919 ? (smtp_transport_options_block *)tb->options_block
3920 : &smtp_transport_option_defaults;
3921 exim_openssl_client_tls_ctx * exim_client_ctx;
3922 uschar * expciphers;
3924 static uschar peerdn[256];
3926 #ifndef DISABLE_OCSP
3927 BOOL request_ocsp = FALSE;
3928 BOOL require_ocsp = FALSE;
3932 store_pool = POOL_PERM;
3933 exim_client_ctx = store_get(sizeof(exim_openssl_client_tls_ctx), GET_UNTAINTED);
3934 exim_client_ctx->corked = NULL;
3938 tlsp->tlsa_usage = 0;
3941 #ifndef DISABLE_OCSP
3943 # ifdef SUPPORT_DANE
3944 /*XXX this should be moved to caller, to be common across gnutls/openssl */
3945 if ( conn_args->dane
3946 && ob->hosts_request_ocsp[0] == '*'
3947 && ob->hosts_request_ocsp[1] == '\0'
3950 /* Unchanged from default. Use a safer one under DANE */
3951 request_ocsp = TRUE;
3952 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
3953 " {= {4}{$tls_out_tlsa_usage}} } "
3959 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK))
3960 request_ocsp = TRUE;
3962 # ifdef SUPPORT_DANE
3966 verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3970 rc = tls_init(host, ob,
3971 #ifndef DISABLE_OCSP
3972 (void *)(long)request_ocsp,
3974 cookie, &client_static_state, tlsp, errstr);
3975 if (rc != OK) return FALSE;
3977 exim_client_ctx->ctx = client_static_state->lib_state.lib_ctx;
3979 tlsp->certificate_verified = FALSE;
3980 client_verify_callback_called = FALSE;
3984 if (conn_args->dane)
3986 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
3987 other failures should be treated as problems. */
3988 if (ob->dane_require_tls_ciphers &&
3989 !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
3990 &expciphers, errstr))
3992 if (expciphers && *expciphers == '\0')
3995 normalise_ciphers(&expciphers, ob->dane_require_tls_ciphers);
4000 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
4001 &expciphers, errstr))
4004 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
4005 are separated by underscores. So that I can use either form in my tests, and
4006 also for general convenience, we turn underscores into hyphens here. */
4008 normalise_ciphers(&expciphers, ob->tls_require_ciphers);
4013 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
4014 if (!SSL_CTX_set_cipher_list(exim_client_ctx->ctx, CS expciphers))
4016 tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
4022 if (conn_args->dane)
4024 SSL_CTX_set_verify(exim_client_ctx->ctx,
4025 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
4026 verify_callback_client_dane);
4028 if (!DANESSL_library_init())
4030 tls_error(US"library init", host, NULL, errstr);
4033 if (DANESSL_CTX_init(exim_client_ctx->ctx) <= 0)
4035 tls_error(US"context init", host, NULL, errstr);
4043 if (tls_client_basic_ctx_init(exim_client_ctx->ctx, host, ob,
4044 client_static_state, errstr) != OK)
4049 if (!expand_check(ob->tls_sni, US"tls_sni", &tlsp->sni, errstr))
4052 { DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n"); }
4053 else if (!Ustrlen(tlsp->sni))
4057 #ifndef EXIM_HAVE_OPENSSL_TLSEXT
4058 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
4066 #ifdef EXIM_HAVE_ALPN
4068 const uschar * plist;
4071 if (!tls_alpn_plist(&ob->tls_alpn, &plist, &plen, errstr))
4074 if (SSL_CTX_set_alpn_protos(exim_client_ctx->ctx, plist, plen) != 0)
4076 tls_error(US"alpn init", host, NULL, errstr);
4080 DEBUG(D_tls) debug_printf("Setting TLS ALPN '%s'\n", ob->tls_alpn);
4083 log_write(0, LOG_MAIN, "ALPN unusable with this OpenSSL library version; ignoring \"%s\"\n",
4087 #ifndef DISABLE_TLS_RESUME
4088 /*XXX have_lbserver: another cmdline arg possibly, for continued-conn, but use
4089 will be very low. */
4091 if (!conn_args->have_lbserver) /* wanted for tls_client_resmption_key() */
4092 { DEBUG(D_tls) debug_printf("resumption not supported on continued-connection\n"); }
4093 else if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
4094 tls_client_ctx_resume_prehandshake(exim_client_ctx, conn_args, tlsp, ob);
4098 if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx)))
4100 tls_error(US"SSL_new", host, NULL, errstr);
4103 SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx));
4104 SSL_set_fd(exim_client_ctx->ssl, cctx->sock);
4105 SSL_set_connect_state(exim_client_ctx->ssl);
4107 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
4110 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tlsp->sni);
4111 SSL_set_tlsext_host_name(exim_client_ctx->ssl, tlsp->sni);
4116 if (conn_args->dane)
4117 if (dane_tlsa_load(exim_client_ctx->ssl, host, &conn_args->tlsa_dnsa, errstr) != OK)
4121 #ifndef DISABLE_OCSP
4122 /* Request certificate status at connection-time. If the server
4123 does OCSP stapling we will get the callback (set in tls_init()) */
4124 # ifdef SUPPORT_DANE
4128 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
4129 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
4131 { /* Re-eval now $tls_out_tlsa_usage is populated. If
4132 this means we avoid the OCSP request, we wasted the setup
4133 cost in tls_init(). */
4134 require_ocsp = verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
4135 request_ocsp = require_ocsp
4136 || verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
4143 SSL_set_tlsext_status_type(exim_client_ctx->ssl, TLSEXT_STATUSTYPE_ocsp);
4144 client_static_state->u_ocsp.client.verify_required = require_ocsp;
4145 tlsp->ocsp = OCSP_NOT_RESP;
4149 #ifndef DISABLE_TLS_RESUME
4150 if (!tls_client_ssl_resume_prehandshake(exim_client_ctx->ssl, tlsp, host,
4155 #ifndef DISABLE_EVENT
4156 client_static_state->event_action = tb ? tb->event_action : NULL;
4159 /* There doesn't seem to be a built-in timeout on connection. */
4161 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
4162 sigalrm_seen = FALSE;
4163 ALARM(ob->command_timeout);
4164 rc = SSL_connect(exim_client_ctx->ssl);
4168 if (conn_args->dane)
4169 DANESSL_cleanup(exim_client_ctx->ssl);
4174 tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, errstr);
4180 debug_printf("SSL_connect succeeded\n");
4181 tls_dump_keylog(exim_client_ctx->ssl);
4184 #ifndef DISABLE_TLS_RESUME
4185 tls_client_resume_posthandshake(exim_client_ctx, tlsp);
4188 #ifdef EXIM_HAVE_ALPN
4189 if (ob->tls_alpn) /* We requested. See what was negotiated. */
4191 const uschar * name;
4194 SSL_get0_alpn_selected(exim_client_ctx->ssl, &name, &len);
4196 { DEBUG(D_tls) debug_printf("ALPN negotiated %u: '%.*s'\n", len, (int)*name, name+1); }
4197 else if (verify_check_given_host(CUSS &ob->hosts_require_alpn, host) == OK)
4199 /* Would like to send a relevant fatal Alert, but OpenSSL has no API */
4200 tls_error(US"handshake", host, US"ALPN required but not negotiated", errstr);
4206 #ifdef SSL_get_extms_support
4207 tlsp->ext_master_secret = SSL_get_extms_support(exim_client_ctx->ssl) == 1;
4209 peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn));
4211 tlsp->ver = tlsver_name(exim_client_ctx->ssl);
4212 tlsp->cipher = construct_cipher_name(exim_client_ctx->ssl, tlsp->ver, &tlsp->bits);
4213 tlsp->cipher_stdname = cipher_stdname_ssl(exim_client_ctx->ssl);
4215 /* Record the certificate we presented */
4217 X509 * crt = SSL_get_certificate(exim_client_ctx->ssl);
4218 tlsp->ourcert = crt ? X509_dup(crt) : NULL;
4221 /*XXX will this work with continued-TLS? */
4222 tls_get_channel_binding(exim_client_ctx->ssl, tlsp, GET_TAINTED);
4224 tlsp->active.sock = cctx->sock;
4225 tlsp->active.tls_ctx = exim_client_ctx;
4226 cctx->tls_ctx = exim_client_ctx;
4235 tls_refill(unsigned lim)
4237 SSL * ssl = state_server.lib_state.lib_ssl;
4241 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
4242 ssl_xfer_buffer, ssl_xfer_buffer_size);
4245 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
4246 inbytes = SSL_read(ssl, CS ssl_xfer_buffer,
4247 MIN(ssl_xfer_buffer_size, lim));
4248 error = SSL_get_error(ssl, inbytes);
4249 if (smtp_receive_timeout > 0) ALARM_CLR(0);
4251 if (had_command_timeout) /* set by signal handler */
4252 smtp_command_timeout_exit(); /* does not return */
4253 if (had_command_sigterm)
4254 smtp_command_sigterm_exit();
4255 if (had_data_timeout)
4256 smtp_data_timeout_exit();
4257 if (had_data_sigint)
4258 smtp_data_sigint_exit();
4260 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
4261 closed down, not that the socket itself has been closed down. Revert to
4262 non-SSL handling. */
4266 case SSL_ERROR_NONE:
4269 case SSL_ERROR_ZERO_RETURN:
4270 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
4272 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
4275 tls_close(NULL, TLS_NO_SHUTDOWN);
4278 /* Handle genuine errors */
4280 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4281 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
4282 ssl_xfer_error = TRUE;
4286 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
4287 DEBUG(D_tls) if (error == SSL_ERROR_SYSCALL)
4288 debug_printf(" - syscall %s\n", strerror(errno));
4289 ssl_xfer_error = TRUE;
4293 #ifndef DISABLE_DKIM
4294 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
4296 ssl_xfer_buffer_hwm = inbytes;
4297 ssl_xfer_buffer_lwm = 0;
4302 /*************************************************
4303 * TLS version of getc *
4304 *************************************************/
4306 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
4307 it refills the buffer via the SSL reading function.
4309 Arguments: lim Maximum amount to read/buffer
4310 Returns: the next character or EOF
4312 Only used by the server-side TLS.
4316 tls_getc(unsigned lim)
4318 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
4319 if (!tls_refill(lim))
4320 return ssl_xfer_error ? EOF : smtp_getc(lim);
4322 /* Something in the buffer; return next uschar */
4324 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
4330 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm;
4334 tls_getbuf(unsigned * len)
4339 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
4340 if (!tls_refill(*len))
4342 if (!ssl_xfer_error) return smtp_getbuf(len);
4347 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
4349 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
4350 ssl_xfer_buffer_lwm += size;
4357 tls_get_cache(unsigned lim)
4359 #ifndef DISABLE_DKIM
4360 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
4361 debug_printf("tls_get_cache\n");
4365 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
4371 tls_could_getc(void)
4373 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm
4374 || SSL_pending(state_server.lib_state.lib_ssl) > 0;
4378 /*************************************************
4379 * Read bytes from TLS channel *
4380 *************************************************/
4384 ct_ctx client context pointer, or NULL for the one global server context
4388 Returns: the number of bytes read
4389 -1 after a failed read, including EOF
4391 Only used by the client-side TLS.
4395 tls_read(void * ct_ctx, uschar *buff, size_t len)
4397 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
4398 : state_server.lib_state.lib_ssl;
4402 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
4403 buff, (unsigned int)len);
4406 inbytes = SSL_read(ssl, CS buff, len);
4407 error = SSL_get_error(ssl, inbytes);
4409 if (error == SSL_ERROR_ZERO_RETURN)
4411 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
4414 else if (error != SSL_ERROR_NONE)
4424 /*************************************************
4425 * Write bytes down TLS channel *
4426 *************************************************/
4430 ct_ctx client context pointer, or NULL for the one global server context
4433 more further data expected soon
4435 Returns: the number of bytes after a successful write,
4436 -1 after a failed write
4438 Used by both server-side and client-side TLS. Calling with len zero and more unset
4439 will flush buffered writes; buff can be null for this case.
4443 tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
4446 int outbytes, error;
4448 ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
4449 : state_server.lib_state.lib_ssl;
4450 static gstring * server_corked = NULL;
4451 gstring ** corkedp = ct_ctx
4452 ? &((exim_openssl_client_tls_ctx *)ct_ctx)->corked : &server_corked;
4453 gstring * corked = *corkedp;
4455 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
4456 buff, (unsigned long)len, more ? ", more" : "");
4458 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
4459 "more" is notified. This hack is only ok if small amounts are involved AND only
4460 one stream does it, in one context (i.e. no store reset). Currently it is used
4461 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only.
4462 We support callouts done by the server process by using a separate client
4463 context for the stashed information. */
4464 /* + if PIPE_COMMAND, banner & ehlo-resp for smmtp-on-connect. Suspect there's
4465 a store reset there, so use POOL_PERM. */
4466 /* + if CHUNKING, cmds EHLO,MAIL,RCPT(s),BDAT */
4470 if (!len) buff = US &error; /* dummy just so that string_catn is ok */
4472 int save_pool = store_pool;
4473 store_pool = POOL_PERM;
4475 corked = string_catn(corked, buff, len);
4477 store_pool = save_pool;
4484 buff = CUS corked->s;
4489 for (int left = len; left > 0;)
4491 DEBUG(D_tls) debug_printf("SSL_write(%p, %p, %d)\n", ssl, buff, left);
4493 outbytes = SSL_write(ssl, CS buff, left);
4494 error = SSL_get_error(ssl, outbytes);
4495 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
4498 case SSL_ERROR_NONE: /* the usual case */
4504 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4505 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
4508 case SSL_ERROR_ZERO_RETURN:
4509 log_write(0, LOG_MAIN, "SSL channel closed on write");
4512 case SSL_ERROR_SYSCALL:
4513 if (ct_ctx || errno != ECONNRESET || !f.smtp_in_quit)
4514 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
4515 sender_fullhost ? sender_fullhost : US"<unknown>",
4517 else if (LOGGING(protocol_detail))
4518 log_write(0, LOG_MAIN, "[%s] after QUIT, client reset TCP before"
4519 " SMTP response and TLS close\n", sender_host_address);
4521 DEBUG(D_tls) debug_printf("[%s] SSL_write: after QUIT,"
4522 " client reset TCP before TLS close\n", sender_host_address);
4526 log_write(0, LOG_MAIN, "SSL_write error %d", error);
4537 ct_ctx client TLS context pointer, or NULL for the one global server context
4541 tls_shutdown_wr(void * ct_ctx)
4543 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4544 SSL ** sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4545 int * fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4548 if (*fdp < 0) return; /* TLS was not active */
4550 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
4552 HDEBUG(D_transport|D_tls|D_acl|D_v) debug_printf_indent(" SMTP(TLS shutdown)>>\n");
4553 rc = SSL_shutdown(*sslp);
4554 if (rc < 0) DEBUG(D_tls)
4556 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4557 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4561 /*************************************************
4562 * Close down a TLS session *
4563 *************************************************/
4565 /* This is also called from within a delivery subprocess forked from the
4566 daemon, to shut down the TLS library, without actually doing a shutdown (which
4567 would tamper with the SSL session in the parent process).
4570 ct_ctx client TLS context pointer, or NULL for the one global server context
4571 do_shutdown 0 no data-flush or TLS close-alert
4572 1 if TLS close-alert is to be sent,
4573 2 if also response to be waited for
4577 Used by both server-side and client-side TLS.
4581 tls_close(void * ct_ctx, int do_shutdown)
4583 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4584 SSL ** sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4585 int * fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4587 if (*fdp < 0) return; /* TLS was not active */
4589 if (do_shutdown > TLS_NO_SHUTDOWN)
4592 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
4593 do_shutdown > TLS_SHUTDOWN_NOWAIT ? " (with response-wait)" : "");
4595 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
4597 if ( ( do_shutdown >= TLS_SHUTDOWN_WONLY
4598 || (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
4600 && do_shutdown > TLS_SHUTDOWN_NOWAIT
4603 #ifdef EXIM_TCP_CORK
4604 (void) setsockopt(*fdp, IPPROTO_TCP, EXIM_TCP_CORK, US &off, sizeof(off));
4607 rc = SSL_shutdown(*sslp); /* wait for response */
4611 if (rc < 0) DEBUG(D_tls)
4613 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4614 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4618 if (!o_ctx) /* server side */
4620 #ifndef DISABLE_OCSP
4621 sk_X509_pop_free(state_server.verify_stack, X509_free);
4622 state_server.verify_stack = NULL;
4625 receive_getc = smtp_getc;
4626 receive_getbuf = smtp_getbuf;
4627 receive_get_cache = smtp_get_cache;
4628 receive_hasc = smtp_hasc;
4629 receive_ungetc = smtp_ungetc;
4630 receive_feof = smtp_feof;
4631 receive_ferror = smtp_ferror;
4632 tls_in.active.tls_ctx = NULL;
4634 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
4645 /*************************************************
4646 * Let tls_require_ciphers be checked at startup *
4647 *************************************************/
4649 /* The tls_require_ciphers option, if set, must be something which the
4652 Returns: NULL on success, or error message
4656 tls_validate_require_cipher(void)
4659 uschar * expciphers, * err;
4663 if (!(tls_require_ciphers && *tls_require_ciphers))
4666 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
4668 return US"failed to expand tls_require_ciphers";
4670 if (!(expciphers && *expciphers))
4673 normalise_ciphers(&expciphers, tls_require_ciphers);
4676 if (lib_ctx_new(&ctx, NULL, &err) == OK)
4679 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
4681 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
4683 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4684 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
4685 expciphers, ssl_errstring);
4696 /*************************************************
4697 * Report the library versions. *
4698 *************************************************/
4700 /* There have historically been some issues with binary compatibility in
4701 OpenSSL libraries; if Exim (like many other applications) is built against
4702 one version of OpenSSL but the run-time linker picks up another version,
4703 it can result in serious failures, including crashing with a SIGSEGV. So
4704 report the version found by the compiler and the run-time version.
4706 Note: some OS vendors backport security fixes without changing the version
4707 number/string, and the version date remains unchanged. The _build_ date
4708 will change, so we can more usefully assist with version diagnosis by also
4709 reporting the build date.
4711 Arguments: string to append to
4716 tls_version_report(gstring * g)
4718 return string_fmt_append(g,
4719 "Library version: OpenSSL: Compile: %s\n"
4722 OPENSSL_VERSION_TEXT,
4723 SSLeay_version(SSLEAY_VERSION),
4724 SSLeay_version(SSLEAY_BUILT_ON));
4725 /* third line is 38 characters for the %s and the line is 73 chars long;
4726 the OpenSSL output includes a "built on: " prefix already. */
4732 /*************************************************
4733 * Random number generation *
4734 *************************************************/
4736 /* Pseudo-random number generation. The result is not expected to be
4737 cryptographically strong but not so weak that someone will shoot themselves
4738 in the foot using it as a nonce in input in some email header scheme or
4739 whatever weirdness they'll twist this into. The result should handle fork()
4740 and avoid repeating sequences. OpenSSL handles that for us.
4744 Returns a random number in range [0, max-1]
4748 vaguely_random_number(int max)
4752 static pid_t pidlast = 0;
4754 uschar smallbuf[sizeof(r)];
4760 if (pidnow != pidlast)
4762 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
4763 is unique for each thread", this doesn't apparently apply across processes,
4764 so our own warning from vaguely_random_number_fallback() applies here too.
4765 Fix per PostgreSQL. */
4771 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
4775 gettimeofday(&r.tv, NULL);
4778 RAND_seed(US (&r), sizeof(r));
4780 /* We're after pseudo-random, not random; if we still don't have enough data
4781 in the internal PRNG then our options are limited. We could sleep and hope
4782 for entropy to come along (prayer technique) but if the system is so depleted
4783 in the first place then something is likely to just keep taking it. Instead,
4784 we'll just take whatever little bit of pseudo-random we can still manage to
4787 needed_len = sizeof(r);
4788 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
4789 asked for a number less than 10. */
4790 for (r = max, i = 0; r; ++i)
4796 #ifdef EXIM_HAVE_RAND_PSEUDO
4797 /* We do not care if crypto-strong */
4798 i = RAND_pseudo_bytes(smallbuf, needed_len);
4800 i = RAND_bytes(smallbuf, needed_len);
4806 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
4807 return vaguely_random_number_fallback(max);
4811 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
4814 /* We don't particularly care about weighted results; if someone wants
4815 smooth distribution and cares enough then they should submit a patch then. */
4822 /*************************************************
4823 * OpenSSL option parse *
4824 *************************************************/
4826 /* Parse one option for tls_openssl_options_parse below
4829 name one option name
4830 value place to store a value for it
4831 Returns success or failure in parsing
4837 tls_openssl_one_option_parse(uschar *name, long *value)
4840 int last = exim_openssl_options_size;
4841 while (last > first)
4843 int middle = (first + last)/2;
4844 int c = Ustrcmp(name, exim_openssl_options[middle].name);
4847 *value = exim_openssl_options[middle].value;
4861 /*************************************************
4862 * OpenSSL option parsing logic *
4863 *************************************************/
4865 /* OpenSSL has a number of compatibility options which an administrator might
4866 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
4867 we look like log_selector.
4870 option_spec the administrator-supplied string of options
4871 results ptr to long storage for the options bitmap
4872 Returns success or failure
4876 tls_openssl_options_parse(uschar *option_spec, long *results)
4879 uschar * exp, * end;
4880 BOOL adding, item_parsed;
4882 /* Server: send no (<= TLS1.2) session tickets */
4883 result = SSL_OP_NO_TICKET;
4885 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
4886 from default because it increases BEAST susceptibility. */
4887 #ifdef SSL_OP_NO_SSLv2
4888 result |= SSL_OP_NO_SSLv2;
4890 #ifdef SSL_OP_NO_SSLv3
4891 result |= SSL_OP_NO_SSLv3;
4893 #ifdef SSL_OP_SINGLE_DH_USE
4894 result |= SSL_OP_SINGLE_DH_USE;
4896 #ifdef SSL_OP_NO_RENEGOTIATION
4897 result |= SSL_OP_NO_RENEGOTIATION;
4906 if (!expand_check(option_spec, US"openssl_options", &exp, &end))
4909 for (uschar * s = exp; *s; /**/)
4911 while (isspace(*s)) ++s;
4914 if (*s != '+' && *s != '-')
4916 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
4917 "+ or - expected but found \"%s\"\n", s);
4920 adding = *s++ == '+';
4921 for (end = s; *end && !isspace(*end); ) end++;
4922 item_parsed = tls_openssl_one_option_parse(string_copyn(s, end-s), &item);
4925 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
4928 DEBUG(D_tls) debug_printf("openssl option, %s %08lx: %08lx (%s)\n",
4929 adding ? "adding to " : "removing from", result, item, s);
4941 #endif /*!MACRO_PREDEF*/
4944 /* End of tls-openssl.c */