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)
961 str = US"SSL_connect";
962 else if (where & SSL_ST_ACCEPT)
963 str = US"SSL_accept";
965 str = US"SSL info (undefined)";
967 if (where & SSL_CB_LOOP)
968 debug_printf("%s: %s\n", str, SSL_state_string_long(s));
969 else if (where & SSL_CB_ALERT)
970 debug_printf("SSL3 alert %s:%s:%s\n",
971 str = where & SSL_CB_READ ? US"read" : US"write",
972 SSL_alert_type_string_long(ret), SSL_alert_desc_string_long(ret));
973 else if (where & SSL_CB_EXIT)
976 debug_printf("%s: failed in %s\n", str, SSL_state_string_long(s));
978 debug_printf("%s: error in %s\n", str, SSL_state_string_long(s));
980 else if (where & SSL_CB_HANDSHAKE_START)
981 debug_printf("%s: hshake start: %s\n", str, SSL_state_string_long(s));
982 else if (where & SSL_CB_HANDSHAKE_DONE)
983 debug_printf("%s: hshake done: %s\n", str, SSL_state_string_long(s));
987 #ifdef OPENSSL_HAVE_KEYLOG_CB
989 keylog_callback(const SSL *ssl, const char *line)
993 DEBUG(D_tls) debug_printf("%.200s\n", line);
994 if (!(filename = getenv("SSLKEYLOGFILE"))) return;
995 if (!(fp = fopen(filename, "a"))) return;
996 fprintf(fp, "%s\n", line);
1005 #ifndef DISABLE_EVENT
1007 verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
1008 BOOL *calledp, const BOOL *optionalp, const uschar * what)
1014 ev = tlsp == &tls_out ? client_static_state->event_action : event_action;
1017 DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth);
1018 old_cert = tlsp->peercert;
1019 tlsp->peercert = X509_dup(cert);
1020 /* NB we do not bother setting peerdn */
1021 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth), &errno)))
1023 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
1024 "depth=%d cert=%s: %s",
1025 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1026 what, depth, dn, yield);
1030 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
1031 return 1; /* reject (leaving peercert set) */
1033 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
1034 "(host in tls_try_verify_hosts)\n");
1035 tlsp->verify_override = TRUE;
1037 X509_free(tlsp->peercert);
1038 tlsp->peercert = old_cert;
1044 /*************************************************
1045 * Callback for verification *
1046 *************************************************/
1048 /* The SSL library does certificate verification if set up to do so. This
1049 callback has the current yes/no state is in "state". If verification succeeded,
1050 we set the certificate-verified flag. If verification failed, what happens
1051 depends on whether the client is required to present a verifiable certificate
1054 If verification is optional, we change the state to yes, but still log the
1055 verification error. For some reason (it really would help to have proper
1056 documentation of OpenSSL), this callback function then gets called again, this
1057 time with state = 1. We must take care not to set the private verified flag on
1058 the second time through.
1060 Note: this function is not called if the client fails to present a certificate
1061 when asked. We get here only if a certificate has been received. Handling of
1062 optional verification for this case is done when requesting SSL to verify, by
1063 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
1065 May be called multiple times for different issues with a certificate, even
1066 for a given "depth" in the certificate chain.
1069 preverify_ok current yes/no state as 1/0
1070 x509ctx certificate information.
1071 tlsp per-direction (client vs. server) support data
1072 calledp has-been-called flag
1073 optionalp verification-is-optional flag
1075 Returns: 0 if verification should fail, otherwise 1
1079 verify_callback(int preverify_ok, X509_STORE_CTX * x509ctx,
1080 tls_support * tlsp, BOOL * calledp, BOOL * optionalp)
1082 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
1083 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
1086 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
1088 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
1089 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1090 tlsp == &tls_out ? deliver_host_address : sender_host_address);
1093 dn[sizeof(dn)-1] = '\0';
1095 tlsp->verify_override = FALSE;
1096 if (preverify_ok == 0)
1098 uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])",
1099 *verify_mode, sender_host_address)
1101 log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
1102 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1104 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn);
1108 if (!tlsp->peercert)
1109 tlsp->peercert = X509_dup(cert); /* record failing cert */
1110 return 0; /* reject */
1112 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
1113 "tls_try_verify_hosts)\n");
1114 tlsp->verify_override = TRUE;
1117 else if (depth != 0)
1119 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
1120 #ifndef DISABLE_OCSP
1121 if (tlsp == &tls_out && client_static_state->u_ocsp.client.verify_store)
1122 { /* client, wanting stapling */
1123 /* Add the server cert's signing chain as the one
1124 for the verification of the OCSP stapled information. */
1126 if (!X509_STORE_add_cert(client_static_state->u_ocsp.client.verify_store,
1129 sk_X509_push(client_static_state->verify_stack, cert);
1132 #ifndef DISABLE_EVENT
1133 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
1134 return 0; /* reject, with peercert set */
1139 const uschar * verify_cert_hostnames;
1141 if ( tlsp == &tls_out
1142 && ((verify_cert_hostnames = client_static_state->verify_cert_hostnames)))
1143 /* client, wanting hostname check */
1146 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
1147 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
1148 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
1150 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
1151 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
1154 const uschar * list = verify_cert_hostnames;
1157 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
1158 if ((rc = X509_check_host(cert, CCS name, 0,
1159 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
1160 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
1165 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1166 tlsp == &tls_out ? deliver_host_address : sender_host_address);
1173 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
1176 uschar * extra = verify_mode
1177 ? string_sprintf(" (during %c-verify for [%s])",
1178 *verify_mode, sender_host_address)
1180 log_write(0, LOG_MAIN,
1181 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
1182 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1183 extra, dn, verify_cert_hostnames);
1187 if (!tlsp->peercert)
1188 tlsp->peercert = X509_dup(cert); /* record failing cert */
1189 return 0; /* reject */
1191 DEBUG(D_tls) debug_printf("SSL verify name failure overridden (host in "
1192 "tls_try_verify_hosts)\n");
1193 tlsp->verify_override = TRUE;
1197 #ifndef DISABLE_EVENT
1198 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
1199 return 0; /* reject, with peercert set */
1202 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
1203 *calledp ? "" : " authenticated", dn);
1207 return 1; /* accept, at least for this level */
1211 verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
1213 return verify_callback(preverify_ok, x509ctx, &tls_out,
1214 &client_verify_callback_called, &client_verify_optional);
1218 verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
1220 return verify_callback(preverify_ok, x509ctx, &tls_in,
1221 &server_verify_callback_called, &server_verify_optional);
1227 /* This gets called *by* the dane library verify callback, which interposes
1231 verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
1233 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
1235 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
1236 #ifndef DISABLE_EVENT
1237 BOOL dummy_called, optional = FALSE;
1240 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
1242 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
1243 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1244 deliver_host_address);
1247 dn[sizeof(dn)-1] = '\0';
1249 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
1250 preverify_ok ? "ok":"BAD", depth, dn);
1252 #ifndef DISABLE_EVENT
1253 if (verify_event(&tls_out, cert, depth, dn,
1254 &dummy_called, &optional, US"DANE"))
1255 return 0; /* reject, with peercert set */
1258 if (preverify_ok == 1)
1260 tls_out.dane_verified = TRUE;
1261 #ifndef DISABLE_OCSP
1262 if (client_static_state->u_ocsp.client.verify_store)
1263 { /* client, wanting stapling */
1264 /* Add the server cert's signing chain as the one
1265 for the verification of the OCSP stapled information. */
1267 if (!X509_STORE_add_cert(client_static_state->u_ocsp.client.verify_store,
1270 sk_X509_push(client_static_state->verify_stack, cert);
1276 int err = X509_STORE_CTX_get_error(x509ctx);
1278 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
1279 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
1282 return preverify_ok;
1285 #endif /*SUPPORT_DANE*/
1288 #ifndef DISABLE_OCSP
1289 /*************************************************
1290 * Load OCSP information into state *
1291 *************************************************/
1292 /* Called to load the server OCSP response from the given file into memory, once
1293 caller has determined this is needed. Checks validity. Debugs a message
1296 ASSUMES: single response, for single cert.
1299 state various parts of session state
1300 filename the filename putatively holding an OCSP response
1301 is_pem file is PEM format; otherwise is DER
1305 ocsp_load_response(exim_openssl_state_st * state, const uschar * filename,
1309 OCSP_RESPONSE * resp;
1310 OCSP_BASICRESP * basic_response;
1311 OCSP_SINGLERESP * single_response;
1312 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
1313 STACK_OF(X509) * sk;
1314 unsigned long verify_flags;
1315 int status, reason, i;
1318 debug_printf("tls_ocsp_file (%s) '%s'\n", is_pem ? "PEM" : "DER", filename);
1320 if (!filename || !*filename) return;
1323 if (!(bio = BIO_new_file(CS filename, "rb")))
1325 log_write(0, LOG_MAIN|LOG_PANIC,
1326 "Failed to open OCSP response file \"%s\": %.100s",
1327 filename, ERR_reason_error_string(ERR_get_error()));
1333 uschar * data, * freep;
1336 if (!PEM_read_bio(bio, &dummy, &dummy, &data, &len))
1338 log_write(0, LOG_MAIN|LOG_PANIC, "Failed to read PEM file \"%s\": %.100s",
1339 filename, ERR_reason_error_string(ERR_get_error()));
1343 resp = d2i_OCSP_RESPONSE(NULL, CUSS &data, len);
1344 OPENSSL_free(freep);
1347 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
1352 log_write(0, LOG_MAIN|LOG_PANIC, "Error reading OCSP response from \"%s\": %s",
1353 filename, ERR_reason_error_string(ERR_get_error()));
1357 if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
1359 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
1360 OCSP_response_status_str(status), status);
1366 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1367 OCSP_RESPONSE_print(bp, resp, 0); /* extreme debug: stapling content */
1372 if (!(basic_response = OCSP_response_get1_basic(resp)))
1375 debug_printf("OCSP response parse error: unable to extract basic response.\n");
1379 sk = state->verify_stack;
1380 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
1382 /* May need to expose ability to adjust those flags?
1383 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
1384 OCSP_TRUSTOTHER OCSP_NOINTERN */
1386 /* This does a full verify on the OCSP proof before we load it for serving
1387 up; possibly overkill - just date-checks might be nice enough.
1389 OCSP_basic_verify takes a "store" arg, but does not
1390 use it for the chain verification, which is all we do
1391 when OCSP_NOVERIFY is set. The content from the wire
1392 "basic_response" and a cert-stack "sk" are all that is used.
1394 We have a stack, loaded in setup_certs() if tls_verify_certificates
1395 was a file (not a directory, or "system"). It is unfortunate we
1396 cannot used the connection context store, as that would neatly
1397 handle the "system" case too, but there seems to be no library
1398 function for getting a stack from a store.
1399 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
1400 We do not free the stack since it could be needed a second time for
1403 Separately we might try to replace using OCSP_basic_verify() - which seems to not
1404 be a public interface into the OpenSSL library (there's no manual entry) -
1405 But what with? We also use OCSP_basic_verify in the client stapling callback.
1406 And there we NEED it; we must verify that status... unless the
1407 library does it for us anyway? */
1409 if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0)
1413 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1414 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
1419 /* Here's the simplifying assumption: there's only one response, for the
1420 one certificate we use, and nothing for anything else in a chain. If this
1421 proves false, we need to extract a cert id from our issued cert
1422 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
1423 right cert in the stack and then calls OCSP_single_get0_status()).
1425 I'm hoping to avoid reworking a bunch more of how we handle state here.
1427 XXX that will change when we add support for (TLS1.3) whole-chain stapling
1430 if (!(single_response = OCSP_resp_get0(basic_response, 0)))
1433 debug_printf("Unable to get first response from OCSP basic response.\n");
1437 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
1438 if (status != V_OCSP_CERTSTATUS_GOOD)
1440 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
1441 OCSP_cert_status_str(status), status,
1442 OCSP_crl_reason_str(reason), reason);
1446 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1448 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
1453 /* Add the resp to the list used by tls_server_stapling_cb() */
1455 ocsp_resplist ** op = &state->u_ocsp.server.olist, * oentry;
1456 while (oentry = *op)
1458 *op = oentry = store_get(sizeof(ocsp_resplist), GET_UNTAINTED);
1459 oentry->next = NULL;
1460 oentry->resp = resp;
1465 if (f.running_in_test_harness)
1467 extern char ** environ;
1468 if (environ) for (uschar ** p = USS environ; *p; p++)
1469 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1471 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
1472 goto supply_response;
1480 ocsp_free_response_list(exim_openssl_state_st * state)
1482 for (ocsp_resplist * olist = state->u_ocsp.server.olist; olist;
1483 olist = olist->next)
1484 OCSP_RESPONSE_free(olist->resp);
1485 state->u_ocsp.server.olist = NULL;
1487 #endif /*!DISABLE_OCSP*/
1494 tls_add_certfile(SSL_CTX * sctx, exim_openssl_state_st * cbinfo, uschar * file,
1497 DEBUG(D_tls) debug_printf("tls_certificate file '%s'\n", file);
1498 if (!SSL_CTX_use_certificate_chain_file(sctx, CS file))
1499 return tls_error(string_sprintf(
1500 "SSL_CTX_use_certificate_chain_file file=%s", file),
1501 cbinfo->host, NULL, errstr);
1506 tls_add_pkeyfile(SSL_CTX * sctx, exim_openssl_state_st * cbinfo, uschar * file,
1509 DEBUG(D_tls) debug_printf("tls_privatekey file '%s'\n", file);
1510 if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM))
1511 return tls_error(string_sprintf(
1512 "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr);
1519 /* Called once during tls_init and possibly again during TLS setup, for a
1520 new context, if Server Name Indication was used and tls_sni was seen in
1521 the certificate string.
1524 sctx the SSL_CTX* to update
1525 state various parts of session state
1526 errstr error string pointer
1528 Returns: OK/DEFER/FAIL
1532 tls_expand_session_files(SSL_CTX * sctx, exim_openssl_state_st * state,
1537 if (!state->certificate)
1539 if (!state->is_server) /* client */
1542 if (tls_install_selfsign(sctx, errstr) != OK)
1549 if ( !reexpand_tls_files_for_sni
1550 && ( Ustrstr(state->certificate, US"tls_sni")
1551 || Ustrstr(state->certificate, US"tls_in_sni")
1552 || Ustrstr(state->certificate, US"tls_out_sni")
1554 reexpand_tls_files_for_sni = TRUE;
1556 if (!expand_check(state->certificate, US"tls_certificate", &expanded, errstr))
1560 if (state->is_server)
1562 const uschar * file_list = expanded;
1565 #ifndef DISABLE_OCSP
1566 const uschar * olist = state->u_ocsp.server.file;
1569 BOOL fmt_pem = FALSE;
1572 if (!expand_check(olist, US"tls_ocsp_file", USS &olist, errstr))
1574 if (olist && !*olist)
1577 /* If doing a re-expand after SNI, avoid reloading the OCSP
1578 responses when the list of filenames has not changed.
1579 The creds-invali on content change wipes file_expanded, so that
1580 always reloads here. */
1582 if ( state->u_ocsp.server.file_expanded && olist
1583 && (Ustrcmp(olist, state->u_ocsp.server.file_expanded) == 0))
1585 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
1590 ocsp_free_response_list(state);
1591 state->u_ocsp.server.file_expanded = olist;
1595 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1597 if ((err = tls_add_certfile(sctx, state, file, errstr)))
1600 #ifndef DISABLE_OCSP
1602 if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1604 if (Ustrncmp(ofile, US"PEM ", 4) == 0)
1609 else if (Ustrncmp(ofile, US"DER ", 4) == 0)
1614 ocsp_load_response(state, ofile, fmt_pem);
1617 DEBUG(D_tls) debug_printf("ran out of ocsp file list\n");
1621 else /* would there ever be a need for multiple client certs? */
1622 if ((err = tls_add_certfile(sctx, state, expanded, errstr)))
1625 if ( state->privatekey
1626 && !expand_check(state->privatekey, US"tls_privatekey", &expanded, errstr))
1629 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1630 of the expansion is an empty string, ignore it also, and assume the private
1631 key is in the same file as the certificate. */
1633 if (expanded && *expanded)
1634 if (state->is_server)
1636 const uschar * file_list = expanded;
1640 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1641 if ((err = tls_add_pkeyfile(sctx, state, file, errstr)))
1644 else /* would there ever be a need for multiple client certs? */
1645 if ((err = tls_add_pkeyfile(sctx, state, expanded, errstr)))
1655 /**************************************************
1656 * One-time init credentials for server and client *
1657 **************************************************/
1660 normalise_ciphers(uschar ** ciphers, const uschar * pre_expansion_ciphers)
1662 uschar * s = *ciphers;
1664 if (!s || !Ustrchr(s, '_')) return; /* no change needed */
1666 if (s == pre_expansion_ciphers)
1667 s = string_copy(s); /* get writable copy */
1669 for (uschar * t = s; *t; t++) if (*t == '_') *t = '-';
1674 server_load_ciphers(SSL_CTX * ctx, exim_openssl_state_st * state,
1675 uschar * ciphers, uschar ** errstr)
1677 DEBUG(D_tls) debug_printf("required ciphers: %s\n", ciphers);
1678 if (!SSL_CTX_set_cipher_list(ctx, CS ciphers))
1679 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
1680 state->server_cipher_list = ciphers;
1687 lib_ctx_new(SSL_CTX ** ctxp, host_item * host, uschar ** errstr)
1690 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1691 if (!(ctx = SSL_CTX_new(host ? TLS_client_method() : TLS_server_method())))
1693 if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
1695 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
1697 /* Set up the information callback, which outputs if debugging is at a suitable
1702 SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
1703 #if defined(EXIM_HAVE_OPESSL_TRACE) && !defined(OPENSSL_NO_SSL_TRACE)
1704 /* this needs a debug build of OpenSSL */
1705 SSL_CTX_set_msg_callback(ctx, (void (*)())SSL_trace);
1707 #ifdef OPENSSL_HAVE_KEYLOG_CB
1708 SSL_CTX_set_keylog_callback(ctx, (void (*)())keylog_callback);
1712 /* Automatically re-try reads/writes after renegotiation. */
1713 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
1720 tls_server_creds_init(void)
1723 uschar * dummy_errstr;
1724 unsigned lifetime = 0;
1728 state_server.lib_state = null_tls_preload;
1730 if (lib_ctx_new(&ctx, NULL, &dummy_errstr) != OK)
1732 state_server.lib_state.lib_ctx = ctx;
1734 /* Preload DH params and EC curve */
1736 if (opt_unset_or_noexpand(tls_dhparam))
1738 DEBUG(D_tls) debug_printf("TLS: preloading DH params for server\n");
1739 if (init_dh(ctx, tls_dhparam, &dummy_errstr))
1740 state_server.lib_state.dh = TRUE;
1743 DEBUG(D_tls) debug_printf("TLS: not preloading DH params for server\n");
1744 if (opt_unset_or_noexpand(tls_eccurve))
1746 DEBUG(D_tls) debug_printf("TLS: preloading ECDH curve for server\n");
1747 if (init_ecdh(ctx, &dummy_errstr))
1748 state_server.lib_state.ecdh = TRUE;
1751 DEBUG(D_tls) debug_printf("TLS: not preloading ECDH curve for server\n");
1753 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1754 /* If we can, preload the server-side cert, key and ocsp */
1756 if ( opt_set_and_noexpand(tls_certificate)
1757 # ifndef DISABLE_OCSP
1758 && opt_unset_or_noexpand(tls_ocsp_file)
1760 && opt_unset_or_noexpand(tls_privatekey))
1762 /* Set watches on the filenames. The implementation does de-duplication
1763 so we can just blindly do them all. */
1765 if ( tls_set_watch(tls_certificate, TRUE)
1766 # ifndef DISABLE_OCSP
1767 && tls_set_watch(tls_ocsp_file, TRUE)
1769 && tls_set_watch(tls_privatekey, TRUE))
1771 state_server.certificate = tls_certificate;
1772 state_server.privatekey = tls_privatekey;
1773 #ifndef DISABLE_OCSP
1774 state_server.u_ocsp.server.file = tls_ocsp_file;
1777 DEBUG(D_tls) debug_printf("TLS: preloading server certs\n");
1778 if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
1779 state_server.lib_state.conn_certs = TRUE;
1782 else if ( !tls_certificate && !tls_privatekey
1783 # ifndef DISABLE_OCSP
1787 { /* Generate & preload a selfsigned cert. No files to watch. */
1788 if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
1790 state_server.lib_state.conn_certs = TRUE;
1791 lifetime = f.running_in_test_harness ? 2 : 60 * 60; /* 1 hour */
1795 DEBUG(D_tls) debug_printf("TLS: not preloading server certs\n");
1798 /* If we can, preload the Authorities for checking client certs against.
1799 Actual choice to do verify is made (tls_{,try_}verify_hosts)
1800 at TLS conn startup */
1802 if ( opt_set_and_noexpand(tls_verify_certificates)
1803 && opt_unset_or_noexpand(tls_crl))
1805 /* Watch the default dir also as they are always included */
1807 if ( tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
1808 && tls_set_watch(tls_verify_certificates, FALSE)
1809 && tls_set_watch(tls_crl, FALSE))
1811 DEBUG(D_tls) debug_printf("TLS: preloading CA bundle for server\n");
1813 if (setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, &dummy_errstr)
1815 state_server.lib_state.cabundle = TRUE;
1819 DEBUG(D_tls) debug_printf("TLS: not preloading CA bundle for server\n");
1820 #endif /* EXIM_HAVE_INOTIFY */
1823 /* If we can, preload the ciphers control string */
1825 if (opt_set_and_noexpand(tls_require_ciphers))
1827 DEBUG(D_tls) debug_printf("TLS: preloading cipher list for server\n");
1828 normalise_ciphers(&tls_require_ciphers, tls_require_ciphers);
1829 if (server_load_ciphers(ctx, &state_server, tls_require_ciphers,
1830 &dummy_errstr) == OK)
1831 state_server.lib_state.pri_string = TRUE;
1834 DEBUG(D_tls) debug_printf("TLS: not preloading cipher list for server\n");
1841 /* Preload whatever creds are static, onto a transport. The client can then
1842 just copy the pointer as it starts up.
1843 Called from the daemon after a cache-invalidate with watch set; called from
1844 a queue-run startup with watch clear. */
1847 tls_client_creds_init(transport_instance * t, BOOL watch)
1849 smtp_transport_options_block * ob = t->options_block;
1850 exim_openssl_state_st tpt_dummy_state;
1851 host_item * dummy_host = (host_item *)1;
1852 uschar * dummy_errstr;
1857 ob->tls_preload = null_tls_preload;
1858 if (lib_ctx_new(&ctx, dummy_host, &dummy_errstr) != OK)
1860 ob->tls_preload.lib_ctx = ctx;
1862 tpt_dummy_state.lib_state = ob->tls_preload;
1864 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1865 if ( opt_set_and_noexpand(ob->tls_certificate)
1866 && opt_unset_or_noexpand(ob->tls_privatekey))
1869 || ( tls_set_watch(ob->tls_certificate, FALSE)
1870 && tls_set_watch(ob->tls_privatekey, FALSE)
1873 uschar * pkey = ob->tls_privatekey;
1876 debug_printf("TLS: preloading client certs for transport '%s'\n",t->name);
1878 if ( tls_add_certfile(ctx, &tpt_dummy_state, ob->tls_certificate,
1880 && tls_add_pkeyfile(ctx, &tpt_dummy_state,
1881 pkey ? pkey : ob->tls_certificate,
1884 ob->tls_preload.conn_certs = TRUE;
1889 debug_printf("TLS: not preloading client certs, for transport '%s'\n", t->name);
1892 if ( opt_set_and_noexpand(ob->tls_verify_certificates)
1893 && opt_unset_or_noexpand(ob->tls_crl))
1896 || tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
1897 && tls_set_watch(ob->tls_verify_certificates, FALSE)
1898 && tls_set_watch(ob->tls_crl, FALSE)
1902 debug_printf("TLS: preloading CA bundle for transport '%s'\n", t->name);
1904 if (setup_certs(ctx, ob->tls_verify_certificates,
1905 ob->tls_crl, dummy_host, &dummy_errstr) == OK)
1906 ob->tls_preload.cabundle = TRUE;
1911 debug_printf("TLS: not preloading CA bundle, for transport '%s'\n", t->name);
1913 #endif /*EXIM_HAVE_INOTIFY*/
1917 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1918 /* Invalidate the creds cached, by dropping the current ones.
1919 Call when we notice one of the source files has changed. */
1922 tls_server_creds_invalidate(void)
1924 SSL_CTX_free(state_server.lib_state.lib_ctx);
1925 state_server.lib_state = null_tls_preload;
1926 state_server.u_ocsp.server.file_expanded = NULL;
1931 tls_client_creds_invalidate(transport_instance * t)
1933 smtp_transport_options_block * ob = t->options_block;
1934 SSL_CTX_free(ob->tls_preload.lib_ctx);
1935 ob->tls_preload = null_tls_preload;
1941 tls_server_creds_invalidate(void)
1945 tls_client_creds_invalidate(transport_instance * t)
1948 #endif /*EXIM_HAVE_INOTIFY*/
1952 #ifndef DISABLE_OCSP
1954 x509_store_dump_cert_s_names(X509_STORE * store)
1956 STACK_OF(X509_OBJECT) * roots= store->objs;
1957 static uschar name[256];
1959 for (int i= 0; i < sk_X509_OBJECT_num(roots); i++)
1961 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
1962 if(tmp_obj->type == X509_LU_X509)
1964 X509_NAME * sn = X509_get_subject_name(tmp_obj->data.x509);
1965 if (X509_NAME_oneline(sn, CS name, sizeof(name)))
1967 name[sizeof(name)-1] = '\0';
1968 debug_printf(" %s\n", name);
1977 #ifndef DISABLE_TLS_RESUME
1978 /* Manage the keysets used for encrypting the session tickets, on the server. */
1980 typedef struct { /* Session ticket encryption key */
1983 const EVP_CIPHER * aes_cipher;
1984 uschar aes_key[32]; /* size needed depends on cipher. aes_128 implies 128/8 = 16? */
1985 # if OPENSSL_VERSION_NUMBER < 0x30000000L
1986 const EVP_MD * hmac_hash;
1988 const uschar * hmac_hashname;
1990 uschar hmac_key[16];
1995 static exim_stek exim_tk; /* current key */
1996 static exim_stek exim_tk_old; /* previous key */
2001 time_t t = time(NULL);
2003 if (exim_tk.name[0])
2005 if (exim_tk.renew >= t) return;
2006 exim_tk_old = exim_tk;
2009 if (f.running_in_test_harness) ssl_session_timeout = 6;
2011 DEBUG(D_tls) debug_printf("OpenSSL: %s STEK\n", exim_tk.name[0] ? "rotating" : "creating");
2012 if (RAND_bytes(exim_tk.aes_key, sizeof(exim_tk.aes_key)) <= 0) return;
2013 if (RAND_bytes(exim_tk.hmac_key, sizeof(exim_tk.hmac_key)) <= 0) return;
2014 if (RAND_bytes(exim_tk.name+1, sizeof(exim_tk.name)-1) <= 0) return;
2016 exim_tk.name[0] = 'E';
2017 exim_tk.aes_cipher = EVP_aes_256_cbc();
2018 # if OPENSSL_VERSION_NUMBER < 0x30000000L
2019 exim_tk.hmac_hash = EVP_sha256();
2021 exim_tk.hmac_hashname = US "sha256";
2023 exim_tk.expire = t + ssl_session_timeout;
2024 exim_tk.renew = t + ssl_session_timeout/2;
2030 if (!exim_tk.name[0]) return NULL;
2035 tk_find(const uschar * name)
2037 return memcmp(name, exim_tk.name, sizeof(exim_tk.name)) == 0 ? &exim_tk
2038 : memcmp(name, exim_tk_old.name, sizeof(exim_tk_old.name)) == 0 ? &exim_tk_old
2045 # if OPENSSL_VERSION_NUMBER < 0x30000000L
2053 /*XXX will want these dependent on the ssl session strength */
2054 # if OPENSSL_VERSION_NUMBER < 0x30000000L
2055 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
2056 key->hmac_hash, NULL);
2059 OSSL_PARAM params[3];
2060 uschar * hk = string_copy(key->hmac_hashname); /* need nonconst */
2061 params[0] = OSSL_PARAM_construct_octet_string("key", key->hmac_key, sizeof(key->hmac_key));
2062 params[1] = OSSL_PARAM_construct_utf8_string("digest", CS hk, 0);
2063 params[2] = OSSL_PARAM_construct_end();
2064 if (EVP_MAC_CTX_set_params(hctx, params) == 0)
2066 DEBUG(D_tls) debug_printf("EVP_MAC_CTX_set_params: %s\n",
2067 ERR_reason_error_string(ERR_get_error()));
2068 return 0; /* error in mac initialisation */
2075 /* Callback for session tickets, on server */
2077 ticket_key_callback(SSL * ssl, uschar key_name[16],
2078 uschar * iv, EVP_CIPHER_CTX * c_ctx,
2079 # if OPENSSL_VERSION_NUMBER < 0x30000000L
2086 tls_support * tlsp = state_server.tlsp;
2091 DEBUG(D_tls) debug_printf("ticket_key_callback: create new session\n");
2092 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
2094 if (RAND_bytes(iv, EVP_MAX_IV_LENGTH) <= 0)
2095 return -1; /* insufficient random */
2097 if (!(key = tk_current())) /* current key doesn't exist or isn't valid */
2098 return 0; /* key couldn't be created */
2099 memcpy(key_name, key->name, 16);
2100 DEBUG(D_tls) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - time(NULL));
2102 if (tk_hmac_init(hctx, key) == 0) return 0;
2103 EVP_EncryptInit_ex(c_ctx, key->aes_cipher, NULL, key->aes_key, iv);
2105 DEBUG(D_tls) debug_printf("ticket created\n");
2110 time_t now = time(NULL);
2112 DEBUG(D_tls) debug_printf("ticket_key_callback: retrieve session\n");
2113 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
2115 if (!(key = tk_find(key_name)) || key->expire < now)
2119 debug_printf("ticket not usable (%s)\n", key ? "expired" : "not found");
2120 if (key) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - now);
2125 if (tk_hmac_init(hctx, key) == 0) return 0;
2126 EVP_DecryptInit_ex(c_ctx, key->aes_cipher, NULL, key->aes_key, iv);
2128 DEBUG(D_tls) debug_printf("ticket usable, STEK expire " TIME_T_FMT "\n", key->expire - now);
2130 /* The ticket lifetime and renewal are the same as the STEK lifetime and
2131 renewal, which is overenthusiastic. A factor of, say, 3x longer STEK would
2132 be better. To do that we'd have to encode ticket lifetime in the name as
2133 we don't yet see the restored session. Could check posthandshake for TLS1.3
2134 and trigger a new ticket then, but cannot do that for TLS1.2 */
2135 return key->renew < now ? 2 : 1;
2138 #endif /* !DISABLE_TLS_RESUME */
2143 setup_cert_verify(SSL_CTX * ctx, BOOL optional,
2144 int (*cert_vfy_cb)(int, X509_STORE_CTX *))
2146 /* If verification is optional, don't fail if no certificate */
2148 SSL_CTX_set_verify(ctx,
2149 SSL_VERIFY_PEER | (optional ? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
2154 /*************************************************
2155 * Callback to handle SNI *
2156 *************************************************/
2158 /* Called when acting as server during the TLS session setup if a Server Name
2159 Indication extension was sent by the client.
2161 API documentation is OpenSSL s_server.c implementation.
2164 s SSL* of the current session
2165 ad unknown (part of OpenSSL API) (unused)
2166 arg Callback of "our" registered data
2168 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
2170 XXX might need to change to using ClientHello callback,
2171 per https://www.openssl.org/docs/manmaster/man3/SSL_client_hello_cb_fn.html
2174 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2176 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
2178 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
2179 exim_openssl_state_st *state = (exim_openssl_state_st *) arg;
2181 int old_pool = store_pool;
2182 uschar * dummy_errstr;
2185 return SSL_TLSEXT_ERR_OK;
2187 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
2188 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
2190 /* Make the extension value available for expansion */
2191 store_pool = POOL_PERM;
2192 tls_in.sni = string_copy_taint(US servername, GET_TAINTED);
2193 store_pool = old_pool;
2195 if (!reexpand_tls_files_for_sni)
2196 return SSL_TLSEXT_ERR_OK;
2198 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
2199 not confident that memcpy wouldn't break some internal reference counting.
2200 Especially since there's a references struct member, which would be off. */
2202 if (lib_ctx_new(&server_sni, NULL, &dummy_errstr) != OK)
2205 /* Not sure how many of these are actually needed, since SSL object
2206 already exists. Might even need this selfsame callback, for reneg? */
2209 SSL_CTX * ctx = state_server.lib_state.lib_ctx;
2210 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(ctx));
2211 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(ctx));
2212 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(ctx));
2213 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(ctx));
2214 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
2215 SSL_CTX_set_tlsext_servername_arg(server_sni, state);
2218 if ( !init_dh(server_sni, state->dhparam, &dummy_errstr)
2219 || !init_ecdh(server_sni, &dummy_errstr)
2223 if ( state->server_cipher_list
2224 && !SSL_CTX_set_cipher_list(server_sni, CS state->server_cipher_list))
2227 #ifndef DISABLE_OCSP
2228 if (state->u_ocsp.server.file)
2230 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
2231 SSL_CTX_set_tlsext_status_arg(server_sni, state);
2237 if ( !expand_check(tls_verify_certificates, US"tls_verify_certificates",
2238 &expcerts, &dummy_errstr)
2239 || (rc = setup_certs(server_sni, expcerts, tls_crl, NULL,
2240 &dummy_errstr)) != OK)
2243 if (expcerts && *expcerts)
2244 setup_cert_verify(server_sni, FALSE, verify_callback_server);
2247 /* do this after setup_certs, because this can require the certs for verifying
2248 OCSP information. */
2249 if ((rc = tls_expand_session_files(server_sni, state, &dummy_errstr)) != OK)
2252 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
2253 SSL_set_SSL_CTX(s, server_sni);
2254 return SSL_TLSEXT_ERR_OK;
2256 bad: return SSL_TLSEXT_ERR_ALERT_FATAL;
2258 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
2263 #ifdef EXIM_HAVE_ALPN
2264 /*************************************************
2265 * Callback to handle ALPN *
2266 *************************************************/
2268 /* Called on server if tls_alpn nonblank after expansion,
2269 when client offers ALPN, after the SNI callback.
2270 If set and not matching the list then we dump the connection */
2273 tls_server_alpn_cb(SSL *ssl, const uschar ** out, uschar * outlen,
2274 const uschar * in, unsigned int inlen, void * arg)
2276 server_seen_alpn = TRUE;
2279 debug_printf("Received TLS ALPN offer:");
2280 for (int pos = 0, siz; pos < inlen; pos += siz+1)
2283 if (pos + 1 + siz > inlen) siz = inlen - pos - 1;
2284 debug_printf(" '%.*s'", siz, in + pos + 1);
2286 debug_printf(". Our list: '%s'\n", tls_alpn);
2289 /* Look for an acceptable ALPN */
2291 if ( inlen > 1 /* at least one name */
2292 && in[0]+1 == inlen /* filling the vector, so exactly one name */
2295 const uschar * list = tls_alpn;
2297 for (uschar * name; name = string_nextinlist(&list, &sep, NULL, 0); )
2298 if (Ustrncmp(in+1, name, in[0]) == 0)
2300 *out = in+1; /* we checked for exactly one, so can just point to it */
2302 return SSL_TLSEXT_ERR_OK; /* use ALPN */
2306 /* More than one name from clilent, or name did not match our list. */
2308 /* This will be fatal to the TLS conn; would be nice to kill TCP also.
2309 Maybe as an option in future; for now leave control to the config (must-tls). */
2311 DEBUG(D_tls) debug_printf("TLS ALPN rejected\n");
2312 return SSL_TLSEXT_ERR_ALERT_FATAL;
2314 #endif /* EXIM_HAVE_ALPN */
2318 #ifndef DISABLE_OCSP
2320 /*************************************************
2321 * Callback to handle OCSP Stapling *
2322 *************************************************/
2324 /* Called when acting as server during the TLS session setup if the client
2325 requests OCSP information with a Certificate Status Request.
2327 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
2333 tls_server_stapling_cb(SSL *s, void *arg)
2335 const exim_openssl_state_st * state = arg;
2336 ocsp_resplist * olist = state->u_ocsp.server.olist;
2337 uschar * response_der; /*XXX blob */
2338 int response_der_len;
2341 debug_printf("Received TLS status request (OCSP stapling); %s response list\n",
2342 olist ? "have" : "lack");
2344 tls_in.ocsp = OCSP_NOT_RESP;
2346 return SSL_TLSEXT_ERR_NOACK;
2348 #ifdef EXIM_HAVE_OPESSL_GET0_SERIAL
2350 const X509 * cert_sent = SSL_get_certificate(s);
2351 const ASN1_INTEGER * cert_serial = X509_get0_serialNumber(cert_sent);
2352 const BIGNUM * cert_bn = ASN1_INTEGER_to_BN(cert_serial, NULL);
2354 for (; olist; olist = olist->next)
2356 OCSP_BASICRESP * bs = OCSP_response_get1_basic(olist->resp);
2357 const OCSP_SINGLERESP * single = OCSP_resp_get0(bs, 0);
2358 const OCSP_CERTID * cid = OCSP_SINGLERESP_get0_id(single);
2359 ASN1_INTEGER * res_cert_serial;
2360 const BIGNUM * resp_bn;
2361 ASN1_OCTET_STRING * res_cert_iNameHash;
2364 (void) OCSP_id_get0_info(&res_cert_iNameHash, NULL, NULL, &res_cert_serial,
2365 (OCSP_CERTID *) cid);
2366 resp_bn = ASN1_INTEGER_to_BN(res_cert_serial, NULL);
2370 debug_printf("cert serial: %s\n", BN_bn2hex(cert_bn));
2371 debug_printf("resp serial: %s\n", BN_bn2hex(resp_bn));
2374 if (BN_cmp(cert_bn, resp_bn) == 0)
2376 DEBUG(D_tls) debug_printf("matched serial for ocsp\n");
2378 /*XXX TODO: check the rest of the list for duplicate matches.
2379 If any, need to also check the Issuer Name hash.
2380 Without this, we will provide the wrong status in the case of
2385 DEBUG(D_tls) debug_printf("not match serial for ocsp\n");
2389 DEBUG(D_tls) debug_printf("failed to find match for ocsp\n");
2390 return SSL_TLSEXT_ERR_NOACK;
2396 DEBUG(D_tls) debug_printf("OpenSSL version too early to support multi-leaf OCSP\n");
2397 return SSL_TLSEXT_ERR_NOACK;
2401 /*XXX could we do the i2d earlier, rather than during the callback? */
2402 response_der = NULL;
2403 response_der_len = i2d_OCSP_RESPONSE(olist->resp, &response_der);
2404 if (response_der_len <= 0)
2405 return SSL_TLSEXT_ERR_NOACK;
2407 SSL_set_tlsext_status_ocsp_resp(state_server.lib_state.lib_ssl,
2408 response_der, response_der_len);
2409 tls_in.ocsp = OCSP_VFIED;
2410 return SSL_TLSEXT_ERR_OK;
2415 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
2417 BIO_printf(bp, "\t%s: ", str);
2418 ASN1_GENERALIZEDTIME_print(bp, time);
2423 tls_client_stapling_cb(SSL * ssl, void * arg)
2425 exim_openssl_state_st * cbinfo = arg;
2426 const unsigned char * p;
2428 OCSP_RESPONSE * rsp;
2429 OCSP_BASICRESP * bs;
2432 DEBUG(D_tls) debug_printf("Received TLS status callback (OCSP stapling):\n");
2433 len = SSL_get_tlsext_status_ocsp_resp(ssl, &p);
2435 { /* Expect this when we requested ocsp but got none */
2436 if (SSL_session_reused(ssl) && tls_out.ocsp == OCSP_VFIED)
2438 DEBUG(D_tls) debug_printf(" null, but resumed; ocsp vfy stored with session is good\n");
2441 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
2442 log_write(0, LOG_MAIN, "Required TLS certificate status not received");
2444 DEBUG(D_tls) debug_printf(" null\n");
2445 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2448 if (!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
2450 tls_out.ocsp = OCSP_FAILED; /*XXX should use tlsp-> to permit concurrent outbound */
2451 if (LOGGING(tls_cipher))
2452 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
2454 DEBUG(D_tls) debug_printf(" parse error\n");
2458 if (!(bs = OCSP_response_get1_basic(rsp)))
2460 tls_out.ocsp = OCSP_FAILED;
2461 if (LOGGING(tls_cipher))
2462 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
2464 DEBUG(D_tls) debug_printf(" error parsing response\n");
2465 OCSP_RESPONSE_free(rsp);
2469 /* We'd check the nonce here if we'd put one in the request. */
2470 /* However that would defeat cacheability on the server so we don't. */
2472 /* This section of code reworked from OpenSSL apps source;
2473 The OpenSSL Project retains copyright:
2474 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
2478 #ifndef EXIM_HAVE_OCSP_RESP_COUNT
2479 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
2482 DEBUG(D_tls) bp = BIO_new(BIO_s_mem());
2484 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
2486 /* Use the chain that verified the server cert to verify the stapled info */
2487 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
2489 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
2490 cbinfo->u_ocsp.client.verify_store, OCSP_NOEXPLICIT)) <= 0)
2491 if (ERR_peek_error())
2493 tls_out.ocsp = OCSP_FAILED;
2494 if (LOGGING(tls_cipher))
2496 const uschar * errstr = CUS ERR_reason_error_string(ERR_peek_error());
2497 static uschar peerdn[256];
2498 X509_NAME_oneline(X509_get_subject_name(SSL_get_peer_certificate(ssl)),
2499 CS peerdn, sizeof(peerdn));
2500 log_write(0, LOG_MAIN,
2501 "[%s] %s Received TLS cert (DN: '%.*s') status response, "
2502 "itself unverifiable: %s",
2503 sender_host_address, sender_host_name,
2504 (int)sizeof(peerdn), peerdn,
2509 BIO_printf(bp, "OCSP response verify failure\n");
2510 ERR_print_errors(bp);
2511 OCSP_RESPONSE_print(bp, rsp, 0);
2516 DEBUG(D_tls) debug_printf("no explicit trust for OCSP signing"
2517 " in the root CA certificate; ignoring\n");
2519 DEBUG(D_tls) debug_printf("OCSP response well-formed and signed OK\n");
2521 /*XXX So we have a good stapled OCSP status. How do we know
2522 it is for the cert of interest? OpenSSL 1.1.0 has a routine
2523 OCSP_resp_find_status() which matches on a cert id, which presumably
2524 we should use. Making an id needs OCSP_cert_id_new(), which takes
2525 issuerName, issuerKey, serialNumber. Are they all in the cert?
2527 For now, carry on blindly accepting the resp. */
2530 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
2531 OCSP_resp_count(bs) - 1;
2533 sk_OCSP_SINGLERESP_num(sresp) - 1;
2537 OCSP_SINGLERESP * single = OCSP_resp_get0(bs, idx);
2539 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
2541 /*XXX so I can see putting a loop in here to handle a rsp with >1 singleresp
2542 - but what happens with a GnuTLS-style input?
2544 we could do with a debug label for each singleresp
2545 - it has a certID with a serialNumber, but I see no API to get that
2547 status = OCSP_single_get0_status(single, &reason, &rev,
2548 &thisupd, &nextupd);
2552 time_print(bp, "This OCSP Update", thisupd);
2553 if (nextupd) time_print(bp, "Next OCSP Update", nextupd);
2555 if (!OCSP_check_validity(thisupd, nextupd,
2556 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
2558 tls_out.ocsp = OCSP_FAILED;
2559 DEBUG(D_tls) ERR_print_errors(bp);
2560 log_write(0, LOG_MAIN, "OCSP dates invalid");
2564 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
2565 OCSP_cert_status_str(status));
2568 case V_OCSP_CERTSTATUS_GOOD:
2569 continue; /* the idx loop */
2570 case V_OCSP_CERTSTATUS_REVOKED:
2571 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
2572 reason != -1 ? "; reason: " : "",
2573 reason != -1 ? OCSP_crl_reason_str(reason) : "");
2574 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
2577 log_write(0, LOG_MAIN,
2578 "Server certificate status unknown, in OCSP stapling");
2586 tls_out.ocsp = OCSP_VFIED;
2590 tls_out.ocsp = OCSP_FAILED;
2591 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2595 int len = (int) BIO_get_mem_data(bp, CSS &s);
2596 if (len > 0) debug_printf("%.*s", len, s);
2601 OCSP_RESPONSE_free(rsp);
2604 #endif /*!DISABLE_OCSP*/
2607 /*************************************************
2608 * Initialize for TLS *
2609 *************************************************/
2610 /* Called from both server and client code, to do preliminary initialization
2611 of the library. We allocate and return a context structure.
2614 host connected host, if client; NULL if server
2615 ob transport options block, if client; NULL if server
2616 ocsp_file file of stapling info (server); flag for require ocsp (client)
2617 addr address if client; NULL if server (for some randomness)
2618 caller_state place to put pointer to allocated state-struct
2619 errstr error string pointer
2621 Returns: OK/DEFER/FAIL
2625 tls_init(host_item * host, smtp_transport_options_block * ob,
2626 #ifndef DISABLE_OCSP
2629 address_item *addr, exim_openssl_state_st ** caller_state,
2634 exim_openssl_state_st * state;
2637 if (host) /* client */
2639 state = store_malloc(sizeof(exim_openssl_state_st));
2640 memset(state, 0, sizeof(*state));
2641 state->certificate = ob->tls_certificate;
2642 state->privatekey = ob->tls_privatekey;
2643 state->is_server = FALSE;
2644 state->dhparam = NULL;
2645 state->lib_state = ob->tls_preload;
2649 state = &state_server;
2650 state->certificate = tls_certificate;
2651 state->privatekey = tls_privatekey;
2652 state->is_server = TRUE;
2653 state->dhparam = tls_dhparam;
2654 state->lib_state = state_server.lib_state;
2660 if (!state->lib_state.pri_string)
2661 state->server_cipher_list = NULL;
2663 #ifndef DISABLE_EVENT
2664 state->event_action = NULL;
2669 /* It turns out that we need to seed the random number generator this early in
2670 order to get the full complement of ciphers to work. It took me roughly a day
2671 of work to discover this by experiment.
2673 On systems that have /dev/urandom, SSL may automatically seed itself from
2674 there. Otherwise, we have to make something up as best we can. Double check
2677 Although we likely called this before, at daemon startup, this is a chance
2678 to mix in further variable info (time, pid) if needed. */
2680 if (!lib_rand_init(addr))
2681 return tls_error(US"RAND_status", host,
2682 US"unable to seed random number generator", errstr);
2684 /* Apply administrator-supplied work-arounds.
2685 Historically we applied just one requested option,
2686 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
2687 moved to an administrator-controlled list of options to specify and
2688 grandfathered in the first one as the default value for "openssl_options".
2690 No OpenSSL version number checks: the options we accept depend upon the
2691 availability of the option value macros from OpenSSL. */
2694 if (!tls_openssl_options_parse(openssl_options, &init_options))
2695 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
2697 /* Create a context.
2698 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
2699 negotiation in the different methods; as far as I can tell, the only
2700 *_{server,client}_method which allows negotiation is SSLv23, which exists even
2701 when OpenSSL is built without SSLv2 support.
2702 By disabling with openssl_options, we can let admins re-enable with the
2705 if (!(ctx = state->lib_state.lib_ctx))
2707 if ((rc = lib_ctx_new(&ctx, host, errstr)) != OK)
2709 state->lib_state.lib_ctx = ctx;
2712 #ifndef DISABLE_TLS_RESUME
2713 tlsp->resumption = RESUME_SUPPORTED;
2717 #ifndef DISABLE_TLS_RESUME
2718 /* Should the server offer session resumption? */
2719 if (!host && verify_check_host(&tls_resumption_hosts) == OK)
2721 DEBUG(D_tls) debug_printf("tls_resumption_hosts overrides openssl_options\n");
2722 init_options &= ~SSL_OP_NO_TICKET;
2723 tlsp->resumption |= RESUME_SERVER_TICKET; /* server will give ticket on request */
2724 tlsp->host_resumable = TRUE;
2728 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
2729 if (!(SSL_CTX_set_options(ctx, init_options)))
2730 return tls_error(string_sprintf(
2731 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
2734 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
2736 /* We'd like to disable session cache unconditionally, but foolish Outlook
2737 Express clients then give up the first TLS connection and make a second one
2738 (which works). Only when there is an IMAP service on the same machine.
2739 Presumably OE is trying to use the cache for A on B. Leave it enabled for
2740 now, until we work out a decent way of presenting control to the config. It
2741 will never be used because we use a new context every time. */
2743 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
2746 /* Initialize with DH parameters if supplied */
2747 /* Initialize ECDH temp key parameter selection */
2751 if (state->lib_state.dh)
2752 { DEBUG(D_tls) debug_printf("TLS: DH params were preloaded\n"); }
2754 if (!init_dh(ctx, state->dhparam, errstr)) return DEFER;
2756 if (state->lib_state.ecdh)
2757 { DEBUG(D_tls) debug_printf("TLS: ECDH curve was preloaded\n"); }
2759 if (!init_ecdh(ctx, errstr)) return DEFER;
2762 /* Set up certificate and key (and perhaps OCSP info) */
2764 if (state->lib_state.conn_certs)
2767 debug_printf("TLS: %s certs were preloaded\n", host ? "client":"server");
2771 #ifndef DISABLE_OCSP
2772 if (!host) /* server */
2774 state->u_ocsp.server.file = ocsp_file;
2775 state->u_ocsp.server.file_expanded = NULL;
2776 state->u_ocsp.server.olist = NULL;
2779 if ((rc = tls_expand_session_files(ctx, state, errstr)) != OK) return rc;
2782 /* If we need to handle SNI or OCSP, do so */
2784 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2785 # ifndef DISABLE_OCSP
2786 if (!(state->verify_stack = sk_X509_new_null()))
2788 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
2793 if (!host) /* server */
2795 # ifndef DISABLE_OCSP
2796 /* We check u_ocsp.server.file, not server.olist, because we care about if
2797 the option exists, not what the current expansion might be, as SNI might
2798 change the certificate and OCSP file in use between now and the time the
2799 callback is invoked. */
2800 if (state->u_ocsp.server.file)
2802 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
2803 SSL_CTX_set_tlsext_status_arg(ctx, state);
2806 /* We always do this, so that $tls_sni is available even if not used in
2808 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
2809 SSL_CTX_set_tlsext_servername_arg(ctx, state);
2811 # ifdef EXIM_HAVE_ALPN
2812 if (tls_alpn && *tls_alpn)
2815 if ( expand_check(tls_alpn, US"tls_alpn", &exp_alpn, errstr)
2816 && *exp_alpn && !isblank(*exp_alpn))
2818 tls_alpn = exp_alpn; /* subprocess so ok to overwrite */
2819 SSL_CTX_set_alpn_select_cb(ctx, tls_server_alpn_cb, state);
2826 # ifndef DISABLE_OCSP
2828 if(ocsp_file) /* wanting stapling */
2830 if (!(state->u_ocsp.client.verify_store = X509_STORE_new()))
2832 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
2835 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
2836 SSL_CTX_set_tlsext_status_arg(ctx, state);
2841 state->verify_cert_hostnames = NULL;
2843 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
2844 /* Set up the RSA callback */
2845 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
2848 /* Finally, set the session cache timeout, and we are done.
2849 The period appears to be also used for (server-generated) session tickets */
2851 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
2852 DEBUG(D_tls) debug_printf("Initialized TLS\n");
2854 *caller_state = state;
2862 /*************************************************
2863 * Get name of cipher in use *
2864 *************************************************/
2867 Argument: pointer to an SSL structure for the connection
2868 pointer to number of bits for cipher
2869 Returns: pointer to allocated string in perm-pool
2873 construct_cipher_name(SSL * ssl, const uschar * ver, int * bits)
2875 int pool = store_pool;
2876 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
2877 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
2878 the accessor functions use const in the prototype. */
2880 const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
2883 SSL_CIPHER_get_bits(c, bits);
2885 store_pool = POOL_PERM;
2886 s = string_sprintf("%s:%s:%u", ver, SSL_CIPHER_get_name(c), *bits);
2888 DEBUG(D_tls) debug_printf("Cipher: %s\n", s);
2893 /* Get IETF-standard name for ciphersuite.
2894 Argument: pointer to an SSL structure for the connection
2895 Returns: pointer to string
2898 static const uschar *
2899 cipher_stdname_ssl(SSL * ssl)
2901 #ifdef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
2902 return CUS SSL_CIPHER_standard_name(SSL_get_current_cipher(ssl));
2904 ushort id = 0xffff & SSL_CIPHER_get_id(SSL_get_current_cipher(ssl));
2905 return cipher_stdname(id >> 8, id & 0xff);
2910 static const uschar *
2911 tlsver_name(SSL * ssl)
2914 int pool = store_pool;
2916 store_pool = POOL_PERM;
2917 s = string_copy(US SSL_get_version(ssl));
2919 if ((p = Ustrchr(s, 'v'))) /* TLSv1.2 -> TLS1.2 */
2920 for (;; p++) if (!(*p = p[1])) break;
2926 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned siz)
2928 /*XXX we might consider a list-of-certs variable for the cert chain.
2929 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
2930 in list-handling functions, also consider the difference between the entire
2931 chain and the elements sent by the peer. */
2933 tlsp->peerdn = NULL;
2935 /* Will have already noted peercert on a verify fail; possibly not the leaf */
2936 if (!tlsp->peercert)
2937 tlsp->peercert = SSL_get_peer_certificate(ssl);
2938 /* Beware anonymous ciphers which lead to server_cert being NULL */
2940 if (!X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, siz))
2941 { DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n"); }
2944 int oldpool = store_pool;
2946 peerdn[siz-1] = '\0'; /* paranoia */
2947 store_pool = POOL_PERM;
2948 tlsp->peerdn = string_copy(peerdn);
2949 store_pool = oldpool;
2951 /* We used to set CV in the cert-verify callbacks (either plain or dane)
2952 but they don't get called on session-resumption. So use the official
2953 interface, which uses the resumed value. Unfortunately this claims verified
2954 when it actually failed but we're in try-verify mode, due to us wanting the
2955 knowlege that it failed so needing to have the callback and forcing a
2956 permissive return. If we don't force it, the TLS startup is failed.
2957 The extra bit of information is set in verify_override in the cb, stashed
2958 for resumption next to the TLS session, and used here. */
2960 if (!tlsp->verify_override)
2961 tlsp->certificate_verified =
2963 tlsp->dane_verified ||
2965 SSL_get_verify_result(ssl) == X509_V_OK;
2973 /*************************************************
2974 * Set up for verifying certificates *
2975 *************************************************/
2977 #ifndef DISABLE_OCSP
2978 /* Load certs from file, return TRUE on success */
2981 chain_from_pem_file(const uschar * file, STACK_OF(X509) ** vp)
2984 STACK_OF(X509) * verify_stack = *vp;
2987 while (sk_X509_num(verify_stack) > 0)
2988 X509_free(sk_X509_pop(verify_stack));
2990 verify_stack = sk_X509_new_null();
2992 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
2993 for (X509 * x; x = PEM_read_bio_X509(bp, NULL, 0, NULL); )
2994 sk_X509_push(verify_stack, x);
3003 /* Called by both client and server startup; on the server possibly
3004 repeated after a Server Name Indication.
3007 sctx SSL_CTX* to initialise
3008 certs certs file, expanded
3009 crl CRL file or NULL
3010 host NULL in a server; the remote host in a client
3011 errstr error string pointer
3013 Returns: OK/DEFER/FAIL
3017 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host,
3020 uschar *expcerts, *expcrl;
3022 if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
3024 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3026 if (expcerts && *expcerts)
3028 /* Tell the library to use its compiled-in location for the system default
3029 CA bundle. Then add the ones specified in the config, if any. */
3031 if (!SSL_CTX_set_default_verify_paths(sctx))
3032 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
3034 if (Ustrcmp(expcerts, "system") != 0 && Ustrncmp(expcerts, "system,", 7) != 0)
3036 struct stat statbuf;
3038 if (Ustat(expcerts, &statbuf) < 0)
3040 log_write(0, LOG_MAIN|LOG_PANIC,
3041 "failed to stat %s for certificates", expcerts);
3047 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
3048 { file = NULL; dir = expcerts; }
3051 STACK_OF(X509) * verify_stack =
3052 #ifndef DISABLE_OCSP
3053 !host ? state_server.verify_stack :
3056 STACK_OF(X509) ** vp = &verify_stack;
3058 file = expcerts; dir = NULL;
3059 #ifndef DISABLE_OCSP
3060 /* In the server if we will be offering an OCSP proof, load chain from
3061 file for verifying the OCSP proof at load time. */
3063 /*XXX Glitch! The file here is tls_verify_certs: the chain for verifying the client cert.
3064 This is inconsistent with the need to verify the OCSP proof of the server cert.
3067 && statbuf.st_size > 0
3068 && state_server.u_ocsp.server.file
3069 && !chain_from_pem_file(file, vp)
3072 log_write(0, LOG_MAIN|LOG_PANIC,
3073 "failed to load cert chain from %s", file);
3079 /* If a certificate file is empty, the load function fails with an
3080 unhelpful error message. If we skip it, we get the correct behaviour (no
3081 certificates are recognized, but the error message is still misleading (it
3082 says no certificate was supplied). But this is better. */
3084 if ( (!file || statbuf.st_size > 0)
3085 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
3086 return tls_error(US"SSL_CTX_load_verify_locations",
3087 host, NULL, errstr);
3089 /* On the server load the list of CAs for which we will accept certs, for
3090 sending to the client. This is only for the one-file
3091 tls_verify_certificates variant.
3092 If a list isn't loaded into the server, but some verify locations are set,
3093 the server end appears to make a wildcard request for client certs.
3094 Meanwhile, the client library as default behaviour *ignores* the list
3095 we send over the wire - see man SSL_CTX_set_client_cert_cb.
3096 Because of this, and that the dir variant is likely only used for
3097 the public-CA bundle (not for a private CA), not worth fixing. */
3101 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
3102 int i = sk_X509_NAME_num(names);
3104 if (!host) SSL_CTX_set_client_CA_list(sctx, names);
3105 DEBUG(D_tls) debug_printf("Added %d additional certificate authorit%s\n",
3106 i, i>1 ? "ies":"y");
3110 debug_printf("Added dir for additional certificate authorities\n");
3114 /* Handle a certificate revocation list. */
3116 #if OPENSSL_VERSION_NUMBER > 0x00907000L
3118 /* This bit of code is now the version supplied by Lars Mainka. (I have
3119 merely reformatted it into the Exim code style.)
3121 "From here I changed the code to add support for multiple crl's
3122 in pem format in one file or to support hashed directory entries in
3123 pem format instead of a file. This method now uses the library function
3124 X509_STORE_load_locations to add the CRL location to the SSL context.
3125 OpenSSL will then handle the verify against CA certs and CRLs by
3126 itself in the verify callback." */
3128 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
3129 if (expcrl && *expcrl)
3131 struct stat statbufcrl;
3132 if (Ustat(expcrl, &statbufcrl) < 0)
3134 log_write(0, LOG_MAIN|LOG_PANIC,
3135 "failed to stat %s for certificates revocation lists", expcrl);
3140 /* is it a file or directory? */
3142 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
3143 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
3147 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
3153 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
3155 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
3156 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
3158 /* setting the flags to check against the complete crl chain */
3160 X509_STORE_set_flags(cvstore,
3161 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
3165 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
3174 tls_dump_keylog(SSL * ssl)
3176 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3177 BIO * bp = BIO_new(BIO_s_mem());
3180 SSL_SESSION_print_keylog(bp, SSL_get_session(ssl));
3181 len = (int) BIO_get_mem_data(bp, CSS &s);
3182 if (len > 0) debug_printf("%.*s", len, s);
3188 /* Channel-binding info for authenticators
3189 See description in https://paquier.xyz/postgresql-2/channel-binding-openssl/
3194 tls_get_channel_binding(SSL * ssl, tls_support * tlsp, const void * taintval)
3199 #ifdef EXIM_HAVE_EXPORT_CHNL_BNGNG
3200 if (SSL_version(ssl) > TLS1_2_VERSION)
3202 /* It's not documented by OpenSSL how big the output buffer must be.
3203 The OpenSSL testcases use 80 bytes but don't say why. The GnuTLS impl only
3204 serves out 32B. RFC 9266 says it is 32B.
3205 Interop fails unless we use the same each end. */
3208 tlsp->channelbind_exporter = TRUE;
3209 taintval = GET_UNTAINTED;
3210 if (SSL_export_keying_material(ssl,
3211 s = store_get((int)len, taintval), len,
3212 "EXPORTER-Channel-Binding", (size_t) 24,
3219 len = SSL_get_peer_finished(ssl, &c, 0);
3220 len = SSL_get_peer_finished(ssl, s = store_get((int)len, taintval), len);
3225 int old_pool = store_pool;
3226 store_pool = POOL_PERM;
3227 tlsp->channelbinding = b64encode_taint(CUS s, (int)len, taintval);
3228 store_pool = old_pool;
3229 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage %p %p\n", tlsp->channelbinding, tlsp);
3234 /*************************************************
3235 * Start a TLS session in a server *
3236 *************************************************/
3237 /* This is called when Exim is running as a server, after having received
3238 the STARTTLS command. It must respond to that command, and then negotiate
3242 errstr pointer to error message
3244 Returns: OK on success
3245 DEFER for errors before the start of the negotiation
3246 FAIL for errors during the negotiation; the server can't
3251 tls_server_start(uschar ** errstr)
3254 uschar * expciphers;
3255 exim_openssl_state_st * dummy_statep;
3258 static uschar peerdn[256];
3260 /* Check for previous activation */
3262 if (tls_in.active.sock >= 0)
3264 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
3265 smtp_printf("554 Already in TLS\r\n", FALSE);
3269 /* Initialize the SSL library. If it fails, it will already have logged
3272 rc = tls_init(NULL, NULL,
3273 #ifndef DISABLE_OCSP
3276 NULL, &dummy_statep, &tls_in, errstr);
3277 if (rc != OK) return rc;
3278 ctx = state_server.lib_state.lib_ctx;
3280 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
3281 were historically separated by underscores. So that I can use either form in my
3282 tests, and also for general convenience, we turn underscores into hyphens here.
3284 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
3285 for TLS 1.3 . Since we do not call it at present we get the default list:
3286 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
3289 if (state_server.lib_state.pri_string)
3290 { DEBUG(D_tls) debug_printf("TLS: cipher list was preloaded\n"); }
3293 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
3298 normalise_ciphers(&expciphers, tls_require_ciphers);
3299 if ((rc = server_load_ciphers(ctx, &state_server, expciphers, errstr)) != OK)
3304 /* If this is a host for which certificate verification is mandatory or
3305 optional, set up appropriately. */
3307 tls_in.certificate_verified = FALSE;
3309 tls_in.dane_verified = FALSE;
3311 server_verify_callback_called = FALSE;
3313 if (verify_check_host(&tls_verify_hosts) == OK)
3314 server_verify_optional = FALSE;
3315 else if (verify_check_host(&tls_try_verify_hosts) == OK)
3316 server_verify_optional = TRUE;
3322 if (!expand_check(tls_verify_certificates, US"tls_verify_certificates",
3325 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3327 if (state_server.lib_state.cabundle)
3328 { DEBUG(D_tls) debug_printf("TLS: CA bundle for server was preloaded\n"); }
3330 if ((rc = setup_certs(ctx, expcerts, tls_crl, NULL, errstr)) != OK)
3333 if (expcerts && *expcerts)
3334 setup_cert_verify(ctx, server_verify_optional, verify_callback_server);
3338 #ifndef DISABLE_TLS_RESUME
3339 # if OPENSSL_VERSION_NUMBER < 0x30000000L
3340 SSL_CTX_set_tlsext_ticket_key_cb(ctx, ticket_key_callback);
3341 /* despite working, appears to always return failure, so ignoring */
3343 SSL_CTX_set_tlsext_ticket_key_evp_cb(ctx, ticket_key_callback);
3344 /* despite working, appears to always return failure, so ignoring */
3348 #ifdef OPENSSL_HAVE_NUM_TICKETS
3349 # ifndef DISABLE_TLS_RESUME
3350 SSL_CTX_set_num_tickets(ctx, tls_in.host_resumable ? 1 : 0);
3352 SSL_CTX_set_num_tickets(ctx, 0); /* send no TLS1.3 stateful-tickets */
3357 /* Prepare for new connection */
3359 if (!(ssl = SSL_new(ctx)))
3360 return tls_error(US"SSL_new", NULL, NULL, errstr);
3361 state_server.lib_state.lib_ssl = ssl;
3363 /* Warning: we used to SSL_clear(ssl) here, it was removed.
3365 * With the SSL_clear(), we get strange interoperability bugs with
3366 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
3367 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
3369 * The SSL_clear() call is to let an existing SSL* be reused, typically after
3370 * session shutdown. In this case, we have a brand new object and there's no
3371 * obvious reason to immediately clear it. I'm guessing that this was
3372 * originally added because of incomplete initialisation which the clear fixed,
3373 * in some historic release.
3376 /* Set context and tell client to go ahead, except in the case of TLS startup
3377 on connection, where outputting anything now upsets the clients and tends to
3378 make them disconnect. We need to have an explicit fflush() here, to force out
3379 the response. Other smtp_printf() calls do not need it, because in non-TLS
3380 mode, the fflush() happens when smtp_getc() is called. */
3382 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
3383 if (!tls_in.on_connect)
3385 smtp_printf("220 TLS go ahead\r\n", FALSE);
3389 /* Now negotiate the TLS session. We put our own timer on it, since it seems
3390 that the OpenSSL library doesn't. */
3392 SSL_set_wfd(ssl, fileno(smtp_out));
3393 SSL_set_rfd(ssl, fileno(smtp_in));
3394 SSL_set_accept_state(ssl);
3396 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
3399 sigalrm_seen = FALSE;
3400 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3401 rc = SSL_accept(ssl);
3406 int error = SSL_get_error(ssl, rc);
3409 case SSL_ERROR_NONE:
3412 case SSL_ERROR_ZERO_RETURN:
3413 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3414 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
3415 #ifndef DISABLE_EVENT
3416 (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);
3418 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
3421 tls_close(NULL, TLS_NO_SHUTDOWN);
3424 /* Handle genuine errors */
3428 int r = ERR_GET_REASON(ERR_peek_error());
3429 if ( r == SSL_R_WRONG_VERSION_NUMBER
3430 #ifdef SSL_R_VERSION_TOO_LOW
3431 || r == SSL_R_VERSION_TOO_LOW
3433 || r == SSL_R_UNKNOWN_PROTOCOL || r == SSL_R_UNSUPPORTED_PROTOCOL)
3434 s = string_sprintf("(%s)", SSL_get_version(ssl));
3435 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : s, errstr);
3436 #ifndef DISABLE_EVENT
3437 (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);
3443 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
3444 if (error == SSL_ERROR_SYSCALL)
3448 *errstr = US"SSL_accept: TCP connection closed by peer";
3449 #ifndef DISABLE_EVENT
3450 (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);
3454 DEBUG(D_tls) debug_printf(" - syscall %s\n", strerror(errno));
3456 (void) tls_error(US"SSL_accept", NULL,
3457 sigalrm_seen ? US"timed out"
3458 : ERR_peek_error() ? NULL : string_sprintf("ret %d", error),
3460 #ifndef DISABLE_EVENT
3461 (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);
3467 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
3468 ERR_clear_error(); /* Even success can leave errors in the stack. Seen with
3469 anon-authentication ciphersuite negotiated. */
3471 #ifndef DISABLE_TLS_RESUME
3472 if (SSL_session_reused(ssl))
3474 tls_in.resumption |= RESUME_USED;
3475 DEBUG(D_tls) debug_printf("Session reused\n");
3479 #ifdef EXIM_HAVE_ALPN
3480 /* If require-alpn, check server_seen_alpn here. Else abort TLS */
3481 if (!tls_alpn || !*tls_alpn)
3482 { DEBUG(D_tls) debug_printf("TLS: was not watching for ALPN\n"); }
3483 else if (!server_seen_alpn)
3484 if (verify_check_host(&hosts_require_alpn) == OK)
3486 /* We'd like to send a definitive Alert but OpenSSL provides no facility */
3488 tls_error(US"handshake", NULL, US"ALPN required but not negotiated", errstr);
3492 { DEBUG(D_tls) debug_printf("TLS: no ALPN presented in handshake\n"); }
3495 const uschar * name;
3497 SSL_get0_alpn_selected(ssl, &name, &len);
3499 debug_printf("ALPN negotiated: '%.*s'\n", (int)*name, name+1);
3501 debug_printf("ALPN: no protocol negotiated\n");
3506 /* TLS has been set up. Record data for the connection,
3507 adjust the input functions to read via TLS, and initialize things. */
3509 #ifdef SSL_get_extms_support
3510 /*XXX what does this return for tls1.3 ? */
3511 tls_in.ext_master_secret = SSL_get_extms_support(ssl) == 1;
3513 peer_cert(ssl, &tls_in, peerdn, sizeof(peerdn));
3515 tls_in.ver = tlsver_name(ssl);
3516 tls_in.cipher = construct_cipher_name(ssl, tls_in.ver, &tls_in.bits);
3517 tls_in.cipher_stdname = cipher_stdname_ssl(ssl);
3522 if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)))
3523 debug_printf("Shared ciphers: %s\n", buf);
3525 tls_dump_keylog(ssl);
3527 #ifdef EXIM_HAVE_SESSION_TICKET
3529 SSL_SESSION * ss = SSL_get_session(ssl);
3530 if (SSL_SESSION_has_ticket(ss)) /* 1.1.0 */
3531 debug_printf("The session has a ticket, life %lu seconds\n",
3532 SSL_SESSION_get_ticket_lifetime_hint(ss));
3537 /* Record the certificate we presented */
3539 X509 * crt = SSL_get_certificate(ssl);
3540 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
3543 tls_get_channel_binding(ssl, &tls_in, GET_UNTAINTED);
3545 /* Only used by the server-side tls (tls_in), including tls_getc.
3546 Client-side (tls_out) reads (seem to?) go via
3547 smtp_read_response()/ip_recv().
3548 Hence no need to duplicate for _in and _out.
3550 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
3551 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
3552 ssl_xfer_eof = ssl_xfer_error = FALSE;
3554 receive_getc = tls_getc;
3555 receive_getbuf = tls_getbuf;
3556 receive_get_cache = tls_get_cache;
3557 receive_hasc = tls_hasc;
3558 receive_ungetc = tls_ungetc;
3559 receive_feof = tls_feof;
3560 receive_ferror = tls_ferror;
3562 tls_in.active.sock = fileno(smtp_out);
3563 tls_in.active.tls_ctx = NULL; /* not using explicit ctx for server-side */
3571 tls_client_basic_ctx_init(SSL_CTX * ctx,
3572 host_item * host, smtp_transport_options_block * ob, exim_openssl_state_st * state,
3577 /* Back-compatible old behaviour if tls_verify_certificates is set but both
3578 tls_verify_hosts and tls_try_verify_hosts are not set. Check only the specified
3579 host patterns if one of them is set with content. */
3581 if ( ( ( !ob->tls_verify_hosts || !ob->tls_verify_hosts
3582 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3584 && ( !ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts
3585 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3588 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
3590 client_verify_optional = FALSE;
3591 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
3592 client_verify_optional = TRUE;
3598 if (!expand_check(ob->tls_verify_certificates, US"tls_verify_certificates",
3601 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3603 if (state->lib_state.cabundle)
3604 { DEBUG(D_tls) debug_printf("TLS: CA bundle was preloaded\n"); }
3606 if ((rc = setup_certs(ctx, expcerts, ob->tls_crl, host, errstr)) != OK)
3609 if (expcerts && *expcerts)
3610 setup_cert_verify(ctx, client_verify_optional, verify_callback_client);
3613 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
3615 state->verify_cert_hostnames =
3617 string_domain_utf8_to_alabel(host->certname, NULL);
3621 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
3622 state->verify_cert_hostnames);
3630 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
3633 const char * hostnames[2] = { CS host->name, NULL };
3636 if (DANESSL_init(ssl, NULL, hostnames) != 1)
3637 return tls_error(US"hostnames load", host, NULL, errstr);
3639 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
3640 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
3641 ) if (rr->type == T_TLSA && rr->size > 3)
3643 const uschar * p = rr->data;
3644 uint8_t usage, selector, mtype;
3645 const char * mdname;
3649 /* Only DANE-TA(2) and DANE-EE(3) are supported */
3650 if (usage != 2 && usage != 3) continue;
3657 default: continue; /* Only match-types 0, 1, 2 are supported */
3658 case 0: mdname = NULL; break;
3659 case 1: mdname = "sha256"; break;
3660 case 2: mdname = "sha512"; break;
3664 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
3667 return tls_error(US"tlsa load", host, NULL, errstr);
3668 case 0: /* action not taken */
3672 tls_out.tlsa_usage |= 1<<usage;
3678 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
3681 #endif /*SUPPORT_DANE*/
3685 #ifndef DISABLE_TLS_RESUME
3686 /* On the client, get any stashed session for the given IP from hints db
3687 and apply it to the ssl-connection for attempted resumption. */
3690 tls_retrieve_session(tls_support * tlsp, SSL * ssl)
3692 if (tlsp->host_resumable)
3694 const uschar * key = tlsp->resume_index;
3695 dbdata_tls_session * dt;
3697 open_db dbblock, * dbm_file;
3699 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
3701 debug_printf("checking for resumable session for %s\n", tlsp->resume_index);
3702 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3704 if ((dt = dbfn_read_with_length(dbm_file, tlsp->resume_index, &len)))
3706 SSL_SESSION * ss = NULL;
3707 const uschar * sess_asn1 = dt->session;
3709 len -= sizeof(dbdata_tls_session);
3710 if (!(d2i_SSL_SESSION(&ss, &sess_asn1, (long)len)))
3714 ERR_error_string_n(ERR_get_error(),
3715 ssl_errstring, sizeof(ssl_errstring));
3716 debug_printf("decoding session: %s\n", ssl_errstring);
3721 unsigned long lifetime =
3722 #ifdef EXIM_HAVE_SESSION_TICKET
3723 SSL_SESSION_get_ticket_lifetime_hint(ss);
3724 #else /* Use, fairly arbitrilarily, what we as server would */
3725 f.running_in_test_harness ? 6 : ssl_session_timeout;
3727 if (lifetime + dt->time_stamp < time(NULL))
3729 DEBUG(D_tls) debug_printf("session expired\n");
3730 dbfn_delete(dbm_file, tlsp->resume_index);
3732 else if (SSL_set_session(ssl, ss))
3734 DEBUG(D_tls) debug_printf("good session\n");
3735 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
3736 tlsp->verify_override = dt->verify_override;
3737 tlsp->ocsp = dt->ocsp;
3741 ERR_error_string_n(ERR_get_error(),
3742 ssl_errstring, sizeof(ssl_errstring));
3743 debug_printf("applying session to ssl: %s\n", ssl_errstring);
3748 DEBUG(D_tls) debug_printf("no session record\n");
3749 dbfn_close(dbm_file);
3755 /* On the client, save the session for later resumption */
3758 tls_save_session_cb(SSL * ssl, SSL_SESSION * ss)
3760 exim_openssl_state_st * cbinfo = SSL_get_ex_data(ssl, tls_exdata_idx);
3763 DEBUG(D_tls) debug_printf("tls_save_session_cb\n");
3765 if (!cbinfo || !(tlsp = cbinfo->tlsp)->host_resumable) return 0;
3767 # ifdef OPENSSL_HAVE_NUM_TICKETS
3768 if (SSL_SESSION_is_resumable(ss)) /* 1.1.1 */
3771 int len = i2d_SSL_SESSION(ss, NULL);
3772 int dlen = sizeof(dbdata_tls_session) + len;
3773 dbdata_tls_session * dt = store_get(dlen, GET_TAINTED);
3774 uschar * s = dt->session;
3775 open_db dbblock, * dbm_file;
3777 DEBUG(D_tls) debug_printf("session is resumable\n");
3778 tlsp->resumption |= RESUME_SERVER_TICKET; /* server gave us a ticket */
3780 dt->verify_override = tlsp->verify_override;
3781 dt->ocsp = tlsp->ocsp;
3782 (void) i2d_SSL_SESSION(ss, &s); /* s gets bumped to end */
3784 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3786 dbfn_write(dbm_file, tlsp->resume_index, dt, dlen);
3787 dbfn_close(dbm_file);
3788 DEBUG(D_tls) debug_printf("wrote session (len %u) to db\n",
3796 /* Construct a key for session DB lookup, and setup the SSL_CTX for resumption */
3799 tls_client_ctx_resume_prehandshake(
3800 exim_openssl_client_tls_ctx * exim_client_ctx, smtp_connect_args * conn_args,
3801 tls_support * tlsp, smtp_transport_options_block * ob)
3803 tlsp->host_resumable = TRUE;
3804 tls_client_resmption_key(tlsp, conn_args, ob);
3806 SSL_CTX_set_session_cache_mode(exim_client_ctx->ctx,
3807 SSL_SESS_CACHE_CLIENT
3808 | SSL_SESS_CACHE_NO_INTERNAL | SSL_SESS_CACHE_NO_AUTO_CLEAR);
3809 SSL_CTX_sess_set_new_cb(exim_client_ctx->ctx, tls_save_session_cb);
3813 tls_client_ssl_resume_prehandshake(SSL * ssl, tls_support * tlsp,
3814 host_item * host, uschar ** errstr)
3816 if (tlsp->host_resumable)
3819 debug_printf("tls_resumption_hosts overrides openssl_options, enabling tickets\n");
3820 SSL_clear_options(ssl, SSL_OP_NO_TICKET);
3822 tls_exdata_idx = SSL_get_ex_new_index(0, 0, 0, 0, 0);
3823 if (!SSL_set_ex_data(ssl, tls_exdata_idx, client_static_state))
3825 tls_error(US"set ex_data", host, NULL, errstr);
3828 debug_printf("tls_exdata_idx %d cbinfo %p\n", tls_exdata_idx, client_static_state);
3831 tlsp->resumption = RESUME_SUPPORTED;
3832 /* Pick up a previous session, saved on an old ticket */
3833 tls_retrieve_session(tlsp, ssl);
3838 tls_client_resume_posthandshake(exim_openssl_client_tls_ctx * exim_client_ctx,
3841 if (SSL_session_reused(exim_client_ctx->ssl))
3843 DEBUG(D_tls) debug_printf("The session was reused\n");
3844 tlsp->resumption |= RESUME_USED;
3847 #endif /* !DISABLE_TLS_RESUME */
3850 #ifdef EXIM_HAVE_ALPN
3851 /* Expand and convert an Exim list to an ALPN list. False return for fail.
3852 NULL plist return for silent no-ALPN.
3854 Overwite the passed-in list with the expanded version.
3858 tls_alpn_plist(uschar ** tls_alpn, const uschar ** plist, unsigned * plen,
3863 if (!expand_check(*tls_alpn, US"tls_alpn", &exp_alpn, errstr))
3865 *tls_alpn = exp_alpn;
3869 DEBUG(D_tls) debug_printf("Setting TLS ALPN forced to fail, not sending\n");
3874 /* The server implementation only accepts exactly one protocol name
3875 but it's little extra code complexity in the client. */
3877 const uschar * list = exp_alpn;
3878 uschar * p = store_get(Ustrlen(exp_alpn), exp_alpn), * s, * t;
3882 for (t = p; s = string_nextinlist(&list, &sep, NULL, 0); t += len)
3884 *t++ = len = (uschar) Ustrlen(s);
3887 *plist = (*plen = t - p) ? p : NULL;
3891 #endif /* EXIM_HAVE_ALPN */
3894 /*************************************************
3895 * Start a TLS session in a client *
3896 *************************************************/
3898 /* Called from the smtp transport after STARTTLS has been accepted.
3901 cctx connection context
3902 conn_args connection details
3903 cookie datum for randomness; can be NULL
3904 tlsp record details of TLS channel configuration here; must be non-NULL
3905 errstr error string pointer
3907 Returns: TRUE for success with TLS session context set in connection context,
3912 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
3913 void * cookie, tls_support * tlsp, uschar ** errstr)
3915 host_item * host = conn_args->host; /* for msgs and option-tests */
3916 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
3917 smtp_transport_options_block * ob = tb
3918 ? (smtp_transport_options_block *)tb->options_block
3919 : &smtp_transport_option_defaults;
3920 exim_openssl_client_tls_ctx * exim_client_ctx;
3921 uschar * expciphers;
3923 static uschar peerdn[256];
3925 #ifndef DISABLE_OCSP
3926 BOOL request_ocsp = FALSE;
3927 BOOL require_ocsp = FALSE;
3931 store_pool = POOL_PERM;
3932 exim_client_ctx = store_get(sizeof(exim_openssl_client_tls_ctx), GET_UNTAINTED);
3933 exim_client_ctx->corked = NULL;
3937 tlsp->tlsa_usage = 0;
3940 #ifndef DISABLE_OCSP
3942 # ifdef SUPPORT_DANE
3943 /*XXX this should be moved to caller, to be common across gnutls/openssl */
3944 if ( conn_args->dane
3945 && ob->hosts_request_ocsp[0] == '*'
3946 && ob->hosts_request_ocsp[1] == '\0'
3949 /* Unchanged from default. Use a safer one under DANE */
3950 request_ocsp = TRUE;
3951 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
3952 " {= {4}{$tls_out_tlsa_usage}} } "
3958 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK))
3959 request_ocsp = TRUE;
3961 # ifdef SUPPORT_DANE
3965 verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3969 rc = tls_init(host, ob,
3970 #ifndef DISABLE_OCSP
3971 (void *)(long)request_ocsp,
3973 cookie, &client_static_state, tlsp, errstr);
3974 if (rc != OK) return FALSE;
3976 exim_client_ctx->ctx = client_static_state->lib_state.lib_ctx;
3978 tlsp->certificate_verified = FALSE;
3979 client_verify_callback_called = FALSE;
3983 if (conn_args->dane)
3985 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
3986 other failures should be treated as problems. */
3987 if (ob->dane_require_tls_ciphers &&
3988 !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
3989 &expciphers, errstr))
3991 if (expciphers && *expciphers == '\0')
3994 normalise_ciphers(&expciphers, ob->dane_require_tls_ciphers);
3999 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
4000 &expciphers, errstr))
4003 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
4004 are separated by underscores. So that I can use either form in my tests, and
4005 also for general convenience, we turn underscores into hyphens here. */
4007 normalise_ciphers(&expciphers, ob->tls_require_ciphers);
4012 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
4013 if (!SSL_CTX_set_cipher_list(exim_client_ctx->ctx, CS expciphers))
4015 tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
4021 if (conn_args->dane)
4023 SSL_CTX_set_verify(exim_client_ctx->ctx,
4024 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
4025 verify_callback_client_dane);
4027 if (!DANESSL_library_init())
4029 tls_error(US"library init", host, NULL, errstr);
4032 if (DANESSL_CTX_init(exim_client_ctx->ctx) <= 0)
4034 tls_error(US"context init", host, NULL, errstr);
4042 if (tls_client_basic_ctx_init(exim_client_ctx->ctx, host, ob,
4043 client_static_state, errstr) != OK)
4048 if (!expand_check(ob->tls_sni, US"tls_sni", &tlsp->sni, errstr))
4051 { DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n"); }
4052 else if (!Ustrlen(tlsp->sni))
4056 #ifndef EXIM_HAVE_OPENSSL_TLSEXT
4057 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
4065 #ifdef EXIM_HAVE_ALPN
4067 const uschar * plist;
4070 if (!tls_alpn_plist(&ob->tls_alpn, &plist, &plen, errstr))
4073 if (SSL_CTX_set_alpn_protos(exim_client_ctx->ctx, plist, plen) != 0)
4075 tls_error(US"alpn init", host, NULL, errstr);
4079 DEBUG(D_tls) debug_printf("Setting TLS ALPN '%s'\n", ob->tls_alpn);
4082 log_write(0, LOG_MAIN, "ALPN unusable with this OpenSSL library version; ignoring \"%s\"\n",
4086 #ifndef DISABLE_TLS_RESUME
4087 /*XXX have_lbserver: another cmdline arg possibly, for continued-conn, but use
4088 will be very low. */
4090 if (!conn_args->have_lbserver) /* wanted for tls_client_resmption_key() */
4091 { DEBUG(D_tls) debug_printf("resumption not supported on continued-connection\n"); }
4092 else if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
4093 tls_client_ctx_resume_prehandshake(exim_client_ctx, conn_args, tlsp, ob);
4097 if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx)))
4099 tls_error(US"SSL_new", host, NULL, errstr);
4102 SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx));
4103 SSL_set_fd(exim_client_ctx->ssl, cctx->sock);
4104 SSL_set_connect_state(exim_client_ctx->ssl);
4106 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
4109 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tlsp->sni);
4110 SSL_set_tlsext_host_name(exim_client_ctx->ssl, tlsp->sni);
4115 if (conn_args->dane)
4116 if (dane_tlsa_load(exim_client_ctx->ssl, host, &conn_args->tlsa_dnsa, errstr) != OK)
4120 #ifndef DISABLE_OCSP
4121 /* Request certificate status at connection-time. If the server
4122 does OCSP stapling we will get the callback (set in tls_init()) */
4123 # ifdef SUPPORT_DANE
4127 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
4128 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
4130 { /* Re-eval now $tls_out_tlsa_usage is populated. If
4131 this means we avoid the OCSP request, we wasted the setup
4132 cost in tls_init(). */
4133 require_ocsp = verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
4134 request_ocsp = require_ocsp
4135 || verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
4142 SSL_set_tlsext_status_type(exim_client_ctx->ssl, TLSEXT_STATUSTYPE_ocsp);
4143 client_static_state->u_ocsp.client.verify_required = require_ocsp;
4144 tlsp->ocsp = OCSP_NOT_RESP;
4148 #ifndef DISABLE_TLS_RESUME
4149 if (!tls_client_ssl_resume_prehandshake(exim_client_ctx->ssl, tlsp, host,
4154 #ifndef DISABLE_EVENT
4155 client_static_state->event_action = tb ? tb->event_action : NULL;
4158 /* There doesn't seem to be a built-in timeout on connection. */
4160 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
4161 sigalrm_seen = FALSE;
4162 ALARM(ob->command_timeout);
4163 rc = SSL_connect(exim_client_ctx->ssl);
4167 if (conn_args->dane)
4168 DANESSL_cleanup(exim_client_ctx->ssl);
4173 tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, errstr);
4179 debug_printf("SSL_connect succeeded\n");
4180 tls_dump_keylog(exim_client_ctx->ssl);
4183 #ifndef DISABLE_TLS_RESUME
4184 tls_client_resume_posthandshake(exim_client_ctx, tlsp);
4187 #ifdef EXIM_HAVE_ALPN
4188 if (ob->tls_alpn) /* We requested. See what was negotiated. */
4190 const uschar * name;
4193 SSL_get0_alpn_selected(exim_client_ctx->ssl, &name, &len);
4195 { DEBUG(D_tls) debug_printf("ALPN negotiated %u: '%.*s'\n", len, (int)*name, name+1); }
4196 else if (verify_check_given_host(CUSS &ob->hosts_require_alpn, host) == OK)
4198 /* Would like to send a relevant fatal Alert, but OpenSSL has no API */
4199 tls_error(US"handshake", host, US"ALPN required but not negotiated", errstr);
4205 #ifdef SSL_get_extms_support
4206 tlsp->ext_master_secret = SSL_get_extms_support(exim_client_ctx->ssl) == 1;
4208 peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn));
4210 tlsp->ver = tlsver_name(exim_client_ctx->ssl);
4211 tlsp->cipher = construct_cipher_name(exim_client_ctx->ssl, tlsp->ver, &tlsp->bits);
4212 tlsp->cipher_stdname = cipher_stdname_ssl(exim_client_ctx->ssl);
4214 /* Record the certificate we presented */
4216 X509 * crt = SSL_get_certificate(exim_client_ctx->ssl);
4217 tlsp->ourcert = crt ? X509_dup(crt) : NULL;
4220 /*XXX will this work with continued-TLS? */
4221 tls_get_channel_binding(exim_client_ctx->ssl, tlsp, GET_TAINTED);
4223 tlsp->active.sock = cctx->sock;
4224 tlsp->active.tls_ctx = exim_client_ctx;
4225 cctx->tls_ctx = exim_client_ctx;
4234 tls_refill(unsigned lim)
4236 SSL * ssl = state_server.lib_state.lib_ssl;
4240 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
4241 ssl_xfer_buffer, ssl_xfer_buffer_size);
4244 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
4245 inbytes = SSL_read(ssl, CS ssl_xfer_buffer,
4246 MIN(ssl_xfer_buffer_size, lim));
4247 error = SSL_get_error(ssl, inbytes);
4248 if (smtp_receive_timeout > 0) ALARM_CLR(0);
4250 if (had_command_timeout) /* set by signal handler */
4251 smtp_command_timeout_exit(); /* does not return */
4252 if (had_command_sigterm)
4253 smtp_command_sigterm_exit();
4254 if (had_data_timeout)
4255 smtp_data_timeout_exit();
4256 if (had_data_sigint)
4257 smtp_data_sigint_exit();
4259 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
4260 closed down, not that the socket itself has been closed down. Revert to
4261 non-SSL handling. */
4265 case SSL_ERROR_NONE:
4268 case SSL_ERROR_ZERO_RETURN:
4269 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
4271 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
4274 tls_close(NULL, TLS_NO_SHUTDOWN);
4277 /* Handle genuine errors */
4279 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4280 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
4281 ssl_xfer_error = TRUE;
4285 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
4286 DEBUG(D_tls) if (error == SSL_ERROR_SYSCALL)
4287 debug_printf(" - syscall %s\n", strerror(errno));
4288 ssl_xfer_error = TRUE;
4292 #ifndef DISABLE_DKIM
4293 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
4295 ssl_xfer_buffer_hwm = inbytes;
4296 ssl_xfer_buffer_lwm = 0;
4301 /*************************************************
4302 * TLS version of getc *
4303 *************************************************/
4305 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
4306 it refills the buffer via the SSL reading function.
4308 Arguments: lim Maximum amount to read/buffer
4309 Returns: the next character or EOF
4311 Only used by the server-side TLS.
4315 tls_getc(unsigned lim)
4317 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
4318 if (!tls_refill(lim))
4319 return ssl_xfer_error ? EOF : smtp_getc(lim);
4321 /* Something in the buffer; return next uschar */
4323 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
4329 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm;
4333 tls_getbuf(unsigned * len)
4338 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
4339 if (!tls_refill(*len))
4341 if (!ssl_xfer_error) return smtp_getbuf(len);
4346 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
4348 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
4349 ssl_xfer_buffer_lwm += size;
4356 tls_get_cache(unsigned lim)
4358 #ifndef DISABLE_DKIM
4359 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
4360 debug_printf("tls_get_cache\n");
4364 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
4370 tls_could_getc(void)
4372 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm
4373 || SSL_pending(state_server.lib_state.lib_ssl) > 0;
4377 /*************************************************
4378 * Read bytes from TLS channel *
4379 *************************************************/
4383 ct_ctx client context pointer, or NULL for the one global server context
4387 Returns: the number of bytes read
4388 -1 after a failed read, including EOF
4390 Only used by the client-side TLS.
4394 tls_read(void * ct_ctx, uschar *buff, size_t len)
4396 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
4397 : state_server.lib_state.lib_ssl;
4401 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
4402 buff, (unsigned int)len);
4405 inbytes = SSL_read(ssl, CS buff, len);
4406 error = SSL_get_error(ssl, inbytes);
4408 if (error == SSL_ERROR_ZERO_RETURN)
4410 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
4413 else if (error != SSL_ERROR_NONE)
4423 /*************************************************
4424 * Write bytes down TLS channel *
4425 *************************************************/
4429 ct_ctx client context pointer, or NULL for the one global server context
4432 more further data expected soon
4434 Returns: the number of bytes after a successful write,
4435 -1 after a failed write
4437 Used by both server-side and client-side TLS. Calling with len zero and more unset
4438 will flush buffered writes; buff can be null for this case.
4442 tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
4445 int outbytes, error;
4447 ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
4448 : state_server.lib_state.lib_ssl;
4449 static gstring * server_corked = NULL;
4450 gstring ** corkedp = ct_ctx
4451 ? &((exim_openssl_client_tls_ctx *)ct_ctx)->corked : &server_corked;
4452 gstring * corked = *corkedp;
4454 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
4455 buff, (unsigned long)len, more ? ", more" : "");
4457 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
4458 "more" is notified. This hack is only ok if small amounts are involved AND only
4459 one stream does it, in one context (i.e. no store reset). Currently it is used
4460 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only.
4461 We support callouts done by the server process by using a separate client
4462 context for the stashed information. */
4463 /* + if PIPE_COMMAND, banner & ehlo-resp for smmtp-on-connect. Suspect there's
4464 a store reset there, so use POOL_PERM. */
4465 /* + if CHUNKING, cmds EHLO,MAIL,RCPT(s),BDAT */
4469 if (!len) buff = US &error; /* dummy just so that string_catn is ok */
4471 int save_pool = store_pool;
4472 store_pool = POOL_PERM;
4474 corked = string_catn(corked, buff, len);
4476 store_pool = save_pool;
4483 buff = CUS corked->s;
4488 for (int left = len; left > 0;)
4490 DEBUG(D_tls) debug_printf("SSL_write(%p, %p, %d)\n", ssl, buff, left);
4492 outbytes = SSL_write(ssl, CS buff, left);
4493 error = SSL_get_error(ssl, outbytes);
4494 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
4497 case SSL_ERROR_NONE: /* the usual case */
4503 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4504 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
4507 case SSL_ERROR_ZERO_RETURN:
4508 log_write(0, LOG_MAIN, "SSL channel closed on write");
4511 case SSL_ERROR_SYSCALL:
4512 if (ct_ctx || errno != ECONNRESET || !f.smtp_in_quit)
4513 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
4514 sender_fullhost ? sender_fullhost : US"<unknown>",
4516 else if (LOGGING(protocol_detail))
4517 log_write(0, LOG_MAIN, "[%s] after QUIT, client reset TCP before"
4518 " SMTP response and TLS close\n", sender_host_address);
4520 DEBUG(D_tls) debug_printf("[%s] SSL_write: after QUIT,"
4521 " client reset TCP before TLS close\n", sender_host_address);
4525 log_write(0, LOG_MAIN, "SSL_write error %d", error);
4536 ct_ctx client TLS context pointer, or NULL for the one global server context
4540 tls_shutdown_wr(void * ct_ctx)
4542 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4543 SSL ** sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4544 int * fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4547 if (*fdp < 0) return; /* TLS was not active */
4549 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
4551 HDEBUG(D_transport|D_tls|D_acl|D_v) debug_printf_indent(" SMTP(TLS shutdown)>>\n");
4552 rc = SSL_shutdown(*sslp);
4553 if (rc < 0) DEBUG(D_tls)
4555 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4556 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4560 /*************************************************
4561 * Close down a TLS session *
4562 *************************************************/
4564 /* This is also called from within a delivery subprocess forked from the
4565 daemon, to shut down the TLS library, without actually doing a shutdown (which
4566 would tamper with the SSL session in the parent process).
4569 ct_ctx client TLS context pointer, or NULL for the one global server context
4570 do_shutdown 0 no data-flush or TLS close-alert
4571 1 if TLS close-alert is to be sent,
4572 2 if also response to be waited for
4576 Used by both server-side and client-side TLS.
4580 tls_close(void * ct_ctx, int do_shutdown)
4582 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4583 SSL ** sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4584 int * fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4586 if (*fdp < 0) return; /* TLS was not active */
4588 if (do_shutdown > TLS_NO_SHUTDOWN)
4591 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
4592 do_shutdown > TLS_SHUTDOWN_NOWAIT ? " (with response-wait)" : "");
4594 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
4596 if ( ( do_shutdown >= TLS_SHUTDOWN_WONLY
4597 || (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
4599 && do_shutdown > TLS_SHUTDOWN_NOWAIT
4602 #ifdef EXIM_TCP_CORK
4603 (void) setsockopt(*fdp, IPPROTO_TCP, EXIM_TCP_CORK, US &off, sizeof(off));
4606 rc = SSL_shutdown(*sslp); /* wait for response */
4610 if (rc < 0) DEBUG(D_tls)
4612 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4613 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4617 if (!o_ctx) /* server side */
4619 #ifndef DISABLE_OCSP
4620 sk_X509_pop_free(state_server.verify_stack, X509_free);
4621 state_server.verify_stack = NULL;
4624 receive_getc = smtp_getc;
4625 receive_getbuf = smtp_getbuf;
4626 receive_get_cache = smtp_get_cache;
4627 receive_hasc = smtp_hasc;
4628 receive_ungetc = smtp_ungetc;
4629 receive_feof = smtp_feof;
4630 receive_ferror = smtp_ferror;
4631 tls_in.active.tls_ctx = NULL;
4633 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
4644 /*************************************************
4645 * Let tls_require_ciphers be checked at startup *
4646 *************************************************/
4648 /* The tls_require_ciphers option, if set, must be something which the
4651 Returns: NULL on success, or error message
4655 tls_validate_require_cipher(void)
4658 uschar * expciphers, * err;
4662 if (!(tls_require_ciphers && *tls_require_ciphers))
4665 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
4667 return US"failed to expand tls_require_ciphers";
4669 if (!(expciphers && *expciphers))
4672 normalise_ciphers(&expciphers, tls_require_ciphers);
4675 if (lib_ctx_new(&ctx, NULL, &err) == OK)
4678 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
4680 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
4682 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4683 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
4684 expciphers, ssl_errstring);
4695 /*************************************************
4696 * Report the library versions. *
4697 *************************************************/
4699 /* There have historically been some issues with binary compatibility in
4700 OpenSSL libraries; if Exim (like many other applications) is built against
4701 one version of OpenSSL but the run-time linker picks up another version,
4702 it can result in serious failures, including crashing with a SIGSEGV. So
4703 report the version found by the compiler and the run-time version.
4705 Note: some OS vendors backport security fixes without changing the version
4706 number/string, and the version date remains unchanged. The _build_ date
4707 will change, so we can more usefully assist with version diagnosis by also
4708 reporting the build date.
4710 Arguments: string to append to
4715 tls_version_report(gstring * g)
4717 return string_fmt_append(g,
4718 "Library version: OpenSSL: Compile: %s\n"
4721 OPENSSL_VERSION_TEXT,
4722 SSLeay_version(SSLEAY_VERSION),
4723 SSLeay_version(SSLEAY_BUILT_ON));
4724 /* third line is 38 characters for the %s and the line is 73 chars long;
4725 the OpenSSL output includes a "built on: " prefix already. */
4731 /*************************************************
4732 * Random number generation *
4733 *************************************************/
4735 /* Pseudo-random number generation. The result is not expected to be
4736 cryptographically strong but not so weak that someone will shoot themselves
4737 in the foot using it as a nonce in input in some email header scheme or
4738 whatever weirdness they'll twist this into. The result should handle fork()
4739 and avoid repeating sequences. OpenSSL handles that for us.
4743 Returns a random number in range [0, max-1]
4747 vaguely_random_number(int max)
4751 static pid_t pidlast = 0;
4753 uschar smallbuf[sizeof(r)];
4759 if (pidnow != pidlast)
4761 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
4762 is unique for each thread", this doesn't apparently apply across processes,
4763 so our own warning from vaguely_random_number_fallback() applies here too.
4764 Fix per PostgreSQL. */
4770 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
4774 gettimeofday(&r.tv, NULL);
4777 RAND_seed(US (&r), sizeof(r));
4779 /* We're after pseudo-random, not random; if we still don't have enough data
4780 in the internal PRNG then our options are limited. We could sleep and hope
4781 for entropy to come along (prayer technique) but if the system is so depleted
4782 in the first place then something is likely to just keep taking it. Instead,
4783 we'll just take whatever little bit of pseudo-random we can still manage to
4786 needed_len = sizeof(r);
4787 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
4788 asked for a number less than 10. */
4789 for (r = max, i = 0; r; ++i)
4795 #ifdef EXIM_HAVE_RAND_PSEUDO
4796 /* We do not care if crypto-strong */
4797 i = RAND_pseudo_bytes(smallbuf, needed_len);
4799 i = RAND_bytes(smallbuf, needed_len);
4805 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
4806 return vaguely_random_number_fallback(max);
4810 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
4813 /* We don't particularly care about weighted results; if someone wants
4814 smooth distribution and cares enough then they should submit a patch then. */
4821 /*************************************************
4822 * OpenSSL option parse *
4823 *************************************************/
4825 /* Parse one option for tls_openssl_options_parse below
4828 name one option name
4829 value place to store a value for it
4830 Returns success or failure in parsing
4836 tls_openssl_one_option_parse(uschar *name, long *value)
4839 int last = exim_openssl_options_size;
4840 while (last > first)
4842 int middle = (first + last)/2;
4843 int c = Ustrcmp(name, exim_openssl_options[middle].name);
4846 *value = exim_openssl_options[middle].value;
4860 /*************************************************
4861 * OpenSSL option parsing logic *
4862 *************************************************/
4864 /* OpenSSL has a number of compatibility options which an administrator might
4865 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
4866 we look like log_selector.
4869 option_spec the administrator-supplied string of options
4870 results ptr to long storage for the options bitmap
4871 Returns success or failure
4875 tls_openssl_options_parse(uschar *option_spec, long *results)
4878 uschar * exp, * end;
4879 BOOL adding, item_parsed;
4881 /* Server: send no (<= TLS1.2) session tickets */
4882 result = SSL_OP_NO_TICKET;
4884 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
4885 from default because it increases BEAST susceptibility. */
4886 #ifdef SSL_OP_NO_SSLv2
4887 result |= SSL_OP_NO_SSLv2;
4889 #ifdef SSL_OP_NO_SSLv3
4890 result |= SSL_OP_NO_SSLv3;
4892 #ifdef SSL_OP_SINGLE_DH_USE
4893 result |= SSL_OP_SINGLE_DH_USE;
4895 #ifdef SSL_OP_NO_RENEGOTIATION
4896 result |= SSL_OP_NO_RENEGOTIATION;
4905 if (!expand_check(option_spec, US"openssl_options", &exp, &end))
4908 for (uschar * s = exp; *s; /**/)
4910 while (isspace(*s)) ++s;
4913 if (*s != '+' && *s != '-')
4915 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
4916 "+ or - expected but found \"%s\"\n", s);
4919 adding = *s++ == '+';
4920 for (end = s; *end && !isspace(*end); ) end++;
4921 item_parsed = tls_openssl_one_option_parse(string_copyn(s, end-s), &item);
4924 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
4927 DEBUG(D_tls) debug_printf("openssl option, %s %08lx: %08lx (%s)\n",
4928 adding ? "adding to " : "removing from", result, item, s);
4940 #endif /*!MACRO_PREDEF*/
4943 /* End of tls-openssl.c */