1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2019 */
6 /* Copyright (c) The Exim Maintainers 2020 */
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
84 # define EXIM_NEED_OPENSSL_INIT
86 # if OPENSSL_VERSION_NUMBER >= 0x010000000L \
87 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
88 # define EXIM_HAVE_OPENSSL_CHECKHOST
92 #if !defined(LIBRESSL_VERSION_NUMBER) \
93 || LIBRESSL_VERSION_NUMBER >= 0x20010000L
94 # if !defined(OPENSSL_NO_ECDH)
95 # if OPENSSL_VERSION_NUMBER >= 0x0090800fL
96 # define EXIM_HAVE_ECDH
98 # if OPENSSL_VERSION_NUMBER >= 0x10002000L
99 # define EXIM_HAVE_OPENSSL_EC_NIST2NID
104 #ifndef LIBRESSL_VERSION_NUMBER
105 # if OPENSSL_VERSION_NUMBER >= 0x010101000L
106 # define OPENSSL_HAVE_KEYLOG_CB
107 # define OPENSSL_HAVE_NUM_TICKETS
108 # define EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
110 # define OPENSSL_BAD_SRVR_OURCERT
114 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
115 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
116 # define DISABLE_OCSP
119 #ifndef DISABLE_TLS_RESUME
120 # if OPENSSL_VERSION_NUMBER < 0x0101010L
121 # error OpenSSL version too old for session-resumption
125 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
126 # include <openssl/x509v3.h>
129 #ifndef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
130 # ifndef EXIM_HAVE_OPENSSL_CIPHER_GET_ID
131 # define SSL_CIPHER_get_id(c) (c->id)
133 # ifndef MACRO_PREDEF
134 # include "tls-cipher-stdname.c"
138 /*************************************************
139 * OpenSSL option parse *
140 *************************************************/
142 typedef struct exim_openssl_option {
145 } exim_openssl_option;
146 /* We could use a macro to expand, but we need the ifdef and not all the
147 options document which version they were introduced in. Policylet: include
148 all options unless explicitly for DTLS, let the administrator choose which
151 This list is current as of:
154 XXX could we autobuild this list, as with predefined-macros?
155 Seems just parsing ssl.h for SSL_OP_.* would be enough (except to exclude DTLS).
156 Also allow a numeric literal?
158 static exim_openssl_option exim_openssl_options[] = {
159 /* KEEP SORTED ALPHABETICALLY! */
161 { US"all", (long) SSL_OP_ALL },
163 #ifdef SSL_OP_ALLOW_NO_DHE_KEX
164 { US"allow_no_dhe_kex", SSL_OP_ALLOW_NO_DHE_KEX },
166 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
167 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
169 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
170 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
172 #ifdef SSL_OP_CRYPTOPRO_TLSEXT_BUG
173 { US"cryptopro_tlsext_bug", SSL_OP_CRYPTOPRO_TLSEXT_BUG },
175 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
176 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
178 #ifdef SSL_OP_ENABLE_MIDDLEBOX_COMPAT
179 { US"enable_middlebox_compat", SSL_OP_ENABLE_MIDDLEBOX_COMPAT },
181 #ifdef SSL_OP_EPHEMERAL_RSA
182 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
184 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
185 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
187 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
188 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
190 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
191 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
193 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
194 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
196 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
197 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
199 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
200 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
202 #ifdef SSL_OP_NO_ANTI_REPLAY
203 { US"no_anti_replay", SSL_OP_NO_ANTI_REPLAY },
205 #ifdef SSL_OP_NO_COMPRESSION
206 { US"no_compression", SSL_OP_NO_COMPRESSION },
208 #ifdef SSL_OP_NO_ENCRYPT_THEN_MAC
209 { US"no_encrypt_then_mac", SSL_OP_NO_ENCRYPT_THEN_MAC },
211 #ifdef SSL_OP_NO_RENEGOTIATION
212 { US"no_renegotiation", SSL_OP_NO_RENEGOTIATION },
214 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
215 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
217 #ifdef SSL_OP_NO_SSLv2
218 { US"no_sslv2", SSL_OP_NO_SSLv2 },
220 #ifdef SSL_OP_NO_SSLv3
221 { US"no_sslv3", SSL_OP_NO_SSLv3 },
223 #ifdef SSL_OP_NO_TICKET
224 { US"no_ticket", SSL_OP_NO_TICKET },
226 #ifdef SSL_OP_NO_TLSv1
227 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
229 #ifdef SSL_OP_NO_TLSv1_1
230 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
231 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
232 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
234 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
237 #ifdef SSL_OP_NO_TLSv1_2
238 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
240 #ifdef SSL_OP_NO_TLSv1_3
241 { US"no_tlsv1_3", SSL_OP_NO_TLSv1_3 },
243 #ifdef SSL_OP_PRIORITIZE_CHACHA
244 { US"prioritize_chacha", SSL_OP_PRIORITIZE_CHACHA },
246 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
247 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
249 #ifdef SSL_OP_SINGLE_DH_USE
250 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
252 #ifdef SSL_OP_SINGLE_ECDH_USE
253 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
255 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
256 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
258 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
259 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
261 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
262 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
264 #ifdef SSL_OP_TLS_D5_BUG
265 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
267 #ifdef SSL_OP_TLS_ROLLBACK_BUG
268 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
270 #ifdef SSL_OP_TLSEXT_PADDING
271 { US"tlsext_padding", SSL_OP_TLSEXT_PADDING },
276 static int exim_openssl_options_size = nelem(exim_openssl_options);
277 static long init_options = 0;
286 for (struct exim_openssl_option * o = exim_openssl_options;
287 o < exim_openssl_options + nelem(exim_openssl_options); o++)
289 /* Trailing X is workaround for problem with _OPT_OPENSSL_NO_TLSV1
290 being a ".ifdef _OPT_OPENSSL_NO_TLSV1_3" match */
292 spf(buf, sizeof(buf), US"_OPT_OPENSSL_%T_X", o->name);
293 builtin_macro_create(buf);
296 # ifndef DISABLE_TLS_RESUME
297 builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING );
299 # ifdef SSL_OP_NO_TLSv1_3
300 builtin_macro_create(US"_HAVE_TLS1_3");
302 # ifdef OPENSSL_BAD_SRVR_OURCERT
303 builtin_macro_create(US"_TLS_BAD_MULTICERT_IN_OURCERT");
305 # ifdef EXIM_HAVE_OCSP
306 builtin_macro_create(US"_HAVE_TLS_OCSP");
307 builtin_macro_create(US"_HAVE_TLS_OCSP_LIST");
312 /******************************************************************************/
314 /* Structure for collecting random data for seeding. */
316 typedef struct randstuff {
321 /* Local static variables */
323 static BOOL client_verify_callback_called = FALSE;
324 static BOOL server_verify_callback_called = FALSE;
325 static const uschar *sid_ctx = US"exim";
327 /* We have three different contexts to care about.
329 Simple case: client, `client_ctx`
330 As a client, we can be doing a callout or cut-through delivery while receiving
331 a message. So we have a client context, which should have options initialised
332 from the SMTP Transport. We may also concurrently want to make TLS connections
333 to utility daemons, so client-contexts are allocated and passed around in call
334 args rather than using a gobal.
337 There are two cases: with and without ServerNameIndication from the client.
338 Given TLS SNI, we can be using different keys, certs and various other
339 configuration settings, because they're re-expanded with $tls_sni set. This
340 allows vhosting with TLS. This SNI is sent in the handshake.
341 A client might not send SNI, so we need a fallback, and an initial setup too.
342 So as a server, we start out using `server_ctx`.
343 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
344 `server_sni` from `server_ctx` and then initialise settings by re-expanding
352 } exim_openssl_client_tls_ctx;
355 /* static SSL_CTX *server_ctx = NULL; */
356 /* static SSL *server_ssl = NULL; */
358 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
359 static SSL_CTX *server_sni = NULL;
362 static char ssl_errstring[256];
364 static int ssl_session_timeout = 7200; /* Two hours */
365 static BOOL client_verify_optional = FALSE;
366 static BOOL server_verify_optional = FALSE;
368 static BOOL reexpand_tls_files_for_sni = FALSE;
371 typedef struct ocsp_resp {
372 struct ocsp_resp * next;
373 OCSP_RESPONSE * resp;
376 typedef struct exim_openssl_state {
377 exim_tlslib_state lib_state;
378 #define lib_ctx libdata0
379 #define lib_ssl libdata1
382 uschar * certificate;
386 STACK_OF(X509) *verify_stack; /* chain for verifying the proof */
390 const uschar *file_expanded;
391 ocsp_resplist *olist;
394 X509_STORE *verify_store; /* non-null if status requested */
395 BOOL verify_required;
400 /* these are cached from first expand */
401 uschar * server_cipher_list;
402 /* only passed down to tls_error: */
404 const uschar * verify_cert_hostnames;
405 #ifndef DISABLE_EVENT
406 uschar * event_action;
408 } exim_openssl_state_st;
410 /* should figure out a cleanup of API to handle state preserved per
411 implementation, for various reasons, which can be void * in the APIs.
412 For now, we hack around it. */
413 exim_openssl_state_st *client_static_state = NULL; /*XXX should not use static; multiple concurrent clients! */
414 exim_openssl_state_st state_server = {.is_server = TRUE};
417 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host,
421 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
422 static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
425 static int tls_server_stapling_cb(SSL *s, void *arg);
430 /* Daemon-called, before every connection, key create/rotate */
431 #ifndef DISABLE_TLS_RESUME
432 static void tk_init(void);
433 static int tls_exdata_idx = -1;
437 tls_per_lib_daemon_tick(void)
439 #ifndef DISABLE_TLS_RESUME
444 /* Called once at daemon startup */
447 tls_per_lib_daemon_init(void)
449 tls_daemon_creds_reload();
453 /*************************************************
455 *************************************************/
457 /* Called from lots of places when errors occur before actually starting to do
458 the TLS handshake, that is, while the session is still in clear. Always returns
459 DEFER for a server and FAIL for a client so that most calls can use "return
460 tls_error(...)" to do this processing and then give an appropriate return. A
461 single function is used for both server and client, because it is called from
462 some shared functions.
465 prefix text to include in the logged error
466 host NULL if setting up a server;
467 the connected host if setting up a client
468 msg error message or NULL if we should ask OpenSSL
469 errstr pointer to output error message
471 Returns: OK/DEFER/FAIL
475 tls_error(uschar * prefix, const host_item * host, uschar * msg, uschar ** errstr)
479 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
480 msg = US ssl_errstring;
483 msg = string_sprintf("(%s): %s", prefix, msg);
484 DEBUG(D_tls) debug_printf("TLS error '%s'\n", msg);
485 if (errstr) *errstr = msg;
486 return host ? FAIL : DEFER;
491 /**************************************************
492 * General library initalisation *
493 **************************************************/
496 lib_rand_init(void * addr)
499 if (!RAND_status()) return TRUE;
501 gettimeofday(&r.tv, NULL);
503 RAND_seed(US (&r), sizeof(r));
504 RAND_seed(US big_buffer, big_buffer_size);
505 if (addr) RAND_seed(US addr, sizeof(addr));
507 return RAND_status();
512 tls_openssl_init(void)
514 static BOOL once = FALSE;
518 #ifdef EXIM_NEED_OPENSSL_INIT
519 SSL_load_error_strings(); /* basic set up */
520 OpenSSL_add_ssl_algorithms();
523 #if defined(EXIM_HAVE_SHA256) && !defined(OPENSSL_AUTO_SHA256)
524 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
525 list of available digests. */
526 EVP_add_digest(EVP_sha256());
529 (void) lib_rand_init(NULL);
530 (void) tls_openssl_options_parse(openssl_options, &init_options);
535 /*************************************************
536 * Initialize for DH *
537 *************************************************/
539 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
542 sctx The current SSL CTX (inbound or outbound)
543 dhparam DH parameter file or fixed parameter identity string
544 host connected host, if client; NULL if server
545 errstr error string pointer
547 Returns: TRUE if OK (nothing to set up, or setup worked)
551 init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host, uschar ** errstr)
559 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded, errstr))
562 if (!dhexpanded || !*dhexpanded)
563 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
564 else if (dhexpanded[0] == '/')
566 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
568 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
569 host, US strerror(errno), errstr);
575 if (Ustrcmp(dhexpanded, "none") == 0)
577 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
581 if (!(pem = std_dh_prime_named(dhexpanded)))
583 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
584 host, US strerror(errno), errstr);
587 bio = BIO_new_mem_buf(CS pem, -1);
590 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
593 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
598 /* note: our default limit of 2236 is not a multiple of 8; the limit comes from
599 * an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with
600 * 2236. But older OpenSSL can only report in bytes (octets), not bits.
601 * If someone wants to dance at the edge, then they can raise the limit or use
602 * current libraries. */
603 #ifdef EXIM_HAVE_OPENSSL_DH_BITS
604 /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022
605 * This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */
606 dh_bitsize = DH_bits(dh);
608 dh_bitsize = 8 * DH_size(dh);
611 /* Even if it is larger, we silently return success rather than cause things
612 * to fail out, so that a too-large DH will not knock out all TLS; it's a
613 * debatable choice. */
614 if (dh_bitsize > tls_dh_max_bits)
617 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d\n",
618 dh_bitsize, tls_dh_max_bits);
622 SSL_CTX_set_tmp_dh(sctx, dh);
624 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
625 dhexpanded ? dhexpanded : US"default", dh_bitsize);
637 /*************************************************
638 * Initialize for ECDH *
639 *************************************************/
641 /* Load parameters for ECDH encryption.
643 For now, we stick to NIST P-256 because: it's simple and easy to configure;
644 it avoids any patent issues that might bite redistributors; despite events in
645 the news and concerns over curve choices, we're not cryptographers, we're not
646 pretending to be, and this is "good enough" to be better than no support,
647 protecting against most adversaries. Given another year or two, there might
648 be sufficient clarity about a "right" way forward to let us make an informed
649 decision, instead of a knee-jerk reaction.
651 Longer-term, we should look at supporting both various named curves and
652 external files generated with "openssl ecparam", much as we do for init_dh().
653 We should also support "none" as a value, to explicitly avoid initialisation.
658 sctx The current SSL CTX (inbound or outbound)
659 host connected host, if client; NULL if server
660 errstr error string pointer
662 Returns: TRUE if OK (nothing to set up, or setup worked)
666 init_ecdh(SSL_CTX * sctx, host_item * host, uschar ** errstr)
668 #ifdef OPENSSL_NO_ECDH
677 if (host) /* No ECDH setup for clients, only for servers */
680 # ifndef EXIM_HAVE_ECDH
682 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
686 if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve, errstr))
688 if (!exp_curve || !*exp_curve)
691 /* "auto" needs to be handled carefully.
692 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
693 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
694 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
695 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
696 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
698 if (Ustrcmp(exp_curve, "auto") == 0)
700 #if OPENSSL_VERSION_NUMBER < 0x10002000L
701 DEBUG(D_tls) debug_printf(
702 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
703 exp_curve = US"prime256v1";
705 # if defined SSL_CTRL_SET_ECDH_AUTO
706 DEBUG(D_tls) debug_printf(
707 "ECDH OpenSSL 1.0.2+: temp key parameter settings: autoselection\n");
708 SSL_CTX_set_ecdh_auto(sctx, 1);
711 DEBUG(D_tls) debug_printf(
712 "ECDH OpenSSL 1.1.0+: temp key parameter settings: default selection\n");
718 DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve);
719 if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef
720 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
721 && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef
725 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve),
730 if (!(ecdh = EC_KEY_new_by_curve_name(nid)))
732 tls_error(US"Unable to create ec curve", host, NULL, errstr);
736 /* The "tmp" in the name here refers to setting a temporary key
737 not to the stability of the interface. */
739 if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0))
740 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), host, NULL, errstr);
742 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve);
747 # endif /*EXIM_HAVE_ECDH*/
748 #endif /*OPENSSL_NO_ECDH*/
753 /*************************************************
754 * Expand key and cert file specs *
755 *************************************************/
759 s SSL connection (not used)
763 Returns: pointer to generated key
767 rsa_callback(SSL *s, int export, int keylength)
770 #ifdef EXIM_HAVE_RSA_GENKEY_EX
771 BIGNUM *bn = BN_new();
774 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
776 #ifdef EXIM_HAVE_RSA_GENKEY_EX
777 if ( !BN_set_word(bn, (unsigned long)RSA_F4)
778 || !(rsa_key = RSA_new())
779 || !RSA_generate_key_ex(rsa_key, keylength, bn, NULL)
782 if (!(rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL)))
786 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
787 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
796 /* Create and install a selfsigned certificate, for use in server mode */
799 tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr)
807 where = US"allocating pkey";
808 if (!(pkey = EVP_PKEY_new()))
811 where = US"allocating cert";
812 if (!(x509 = X509_new()))
815 where = US"generating pkey";
816 if (!(rsa = rsa_callback(NULL, 0, 2048)))
819 where = US"assigning pkey";
820 if (!EVP_PKEY_assign_RSA(pkey, rsa))
823 X509_set_version(x509, 2); /* N+1 - version 3 */
824 ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
825 X509_gmtime_adj(X509_get_notBefore(x509), 0);
826 X509_gmtime_adj(X509_get_notAfter(x509), (long)60 * 60); /* 1 hour */
827 X509_set_pubkey(x509, pkey);
829 name = X509_get_subject_name(x509);
830 X509_NAME_add_entry_by_txt(name, "C",
831 MBSTRING_ASC, CUS "UK", -1, -1, 0);
832 X509_NAME_add_entry_by_txt(name, "O",
833 MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0);
834 X509_NAME_add_entry_by_txt(name, "CN",
835 MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0);
836 X509_set_issuer_name(x509, name);
838 where = US"signing cert";
839 if (!X509_sign(x509, pkey, EVP_md5()))
842 where = US"installing selfsign cert";
843 if (!SSL_CTX_use_certificate(sctx, x509))
846 where = US"installing selfsign key";
847 if (!SSL_CTX_use_PrivateKey(sctx, pkey))
853 (void) tls_error(where, NULL, NULL, errstr);
854 if (x509) X509_free(x509);
855 if (pkey) EVP_PKEY_free(pkey);
865 /*************************************************
866 * Information callback *
867 *************************************************/
869 /* The SSL library functions call this from time to time to indicate what they
870 are doing. We copy the string to the debugging output when TLS debugging has
882 info_callback(SSL *s, int where, int ret)
888 if (where & SSL_ST_CONNECT)
889 str = US"SSL_connect";
890 else if (where & SSL_ST_ACCEPT)
891 str = US"SSL_accept";
893 str = US"SSL info (undefined)";
895 if (where & SSL_CB_LOOP)
896 debug_printf("%s: %s\n", str, SSL_state_string_long(s));
897 else if (where & SSL_CB_ALERT)
898 debug_printf("SSL3 alert %s:%s:%s\n",
899 str = where & SSL_CB_READ ? US"read" : US"write",
900 SSL_alert_type_string_long(ret), SSL_alert_desc_string_long(ret));
901 else if (where & SSL_CB_EXIT)
903 debug_printf("%s: failed in %s\n", str, SSL_state_string_long(s));
905 debug_printf("%s: error in %s\n", str, SSL_state_string_long(s));
906 else if (where & SSL_CB_HANDSHAKE_START)
907 debug_printf("%s: hshake start: %s\n", str, SSL_state_string_long(s));
908 else if (where & SSL_CB_HANDSHAKE_DONE)
909 debug_printf("%s: hshake done: %s\n", str, SSL_state_string_long(s));
913 #ifdef OPENSSL_HAVE_KEYLOG_CB
915 keylog_callback(const SSL *ssl, const char *line)
919 DEBUG(D_tls) debug_printf("%.200s\n", line);
920 if (!(filename = getenv("SSLKEYLOGFILE"))) return;
921 if (!(fp = fopen(filename, "a"))) return;
922 fprintf(fp, "%s\n", line);
931 #ifndef DISABLE_EVENT
933 verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
934 BOOL *calledp, const BOOL *optionalp, const uschar * what)
940 ev = tlsp == &tls_out ? client_static_state->event_action : event_action;
943 DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth);
944 old_cert = tlsp->peercert;
945 tlsp->peercert = X509_dup(cert);
946 /* NB we do not bother setting peerdn */
947 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
949 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
950 "depth=%d cert=%s: %s",
951 tlsp == &tls_out ? deliver_host_address : sender_host_address,
952 what, depth, dn, yield);
956 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
957 return 1; /* reject (leaving peercert set) */
959 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
960 "(host in tls_try_verify_hosts)\n");
961 tlsp->verify_override = TRUE;
963 X509_free(tlsp->peercert);
964 tlsp->peercert = old_cert;
970 /*************************************************
971 * Callback for verification *
972 *************************************************/
974 /* The SSL library does certificate verification if set up to do so. This
975 callback has the current yes/no state is in "state". If verification succeeded,
976 we set the certificate-verified flag. If verification failed, what happens
977 depends on whether the client is required to present a verifiable certificate
980 If verification is optional, we change the state to yes, but still log the
981 verification error. For some reason (it really would help to have proper
982 documentation of OpenSSL), this callback function then gets called again, this
983 time with state = 1. We must take care not to set the private verified flag on
984 the second time through.
986 Note: this function is not called if the client fails to present a certificate
987 when asked. We get here only if a certificate has been received. Handling of
988 optional verification for this case is done when requesting SSL to verify, by
989 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
991 May be called multiple times for different issues with a certificate, even
992 for a given "depth" in the certificate chain.
995 preverify_ok current yes/no state as 1/0
996 x509ctx certificate information.
997 tlsp per-direction (client vs. server) support data
998 calledp has-been-called flag
999 optionalp verification-is-optional flag
1001 Returns: 0 if verification should fail, otherwise 1
1005 verify_callback(int preverify_ok, X509_STORE_CTX * x509ctx,
1006 tls_support * tlsp, BOOL * calledp, BOOL * optionalp)
1008 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
1009 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
1012 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
1014 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
1015 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1016 tlsp == &tls_out ? deliver_host_address : sender_host_address);
1019 dn[sizeof(dn)-1] = '\0';
1021 tlsp->verify_override = FALSE;
1022 if (preverify_ok == 0)
1024 uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])",
1025 *verify_mode, sender_host_address)
1027 log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
1028 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1030 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn);
1034 if (!tlsp->peercert)
1035 tlsp->peercert = X509_dup(cert); /* record failing cert */
1036 return 0; /* reject */
1038 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
1039 "tls_try_verify_hosts)\n");
1040 tlsp->verify_override = TRUE;
1043 else if (depth != 0)
1045 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
1046 #ifndef DISABLE_OCSP
1047 if (tlsp == &tls_out && client_static_state->u_ocsp.client.verify_store)
1048 { /* client, wanting stapling */
1049 /* Add the server cert's signing chain as the one
1050 for the verification of the OCSP stapled information. */
1052 if (!X509_STORE_add_cert(client_static_state->u_ocsp.client.verify_store,
1055 sk_X509_push(client_static_state->verify_stack, cert);
1058 #ifndef DISABLE_EVENT
1059 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
1060 return 0; /* reject, with peercert set */
1065 const uschar * verify_cert_hostnames;
1067 if ( tlsp == &tls_out
1068 && ((verify_cert_hostnames = client_static_state->verify_cert_hostnames)))
1069 /* client, wanting hostname check */
1072 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
1073 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
1074 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
1076 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
1077 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
1080 const uschar * list = verify_cert_hostnames;
1083 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
1084 if ((rc = X509_check_host(cert, CCS name, 0,
1085 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
1086 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
1091 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1092 tlsp == &tls_out ? deliver_host_address : sender_host_address);
1099 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
1102 uschar * extra = verify_mode
1103 ? string_sprintf(" (during %c-verify for [%s])",
1104 *verify_mode, sender_host_address)
1106 log_write(0, LOG_MAIN,
1107 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
1108 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1109 extra, dn, verify_cert_hostnames);
1113 if (!tlsp->peercert)
1114 tlsp->peercert = X509_dup(cert); /* record failing cert */
1115 return 0; /* reject */
1117 DEBUG(D_tls) debug_printf("SSL verify name failure overridden (host in "
1118 "tls_try_verify_hosts)\n");
1119 tlsp->verify_override = TRUE;
1123 #ifndef DISABLE_EVENT
1124 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
1125 return 0; /* reject, with peercert set */
1128 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
1129 *calledp ? "" : " authenticated", dn);
1133 return 1; /* accept, at least for this level */
1137 verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
1139 return verify_callback(preverify_ok, x509ctx, &tls_out,
1140 &client_verify_callback_called, &client_verify_optional);
1144 verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
1146 return verify_callback(preverify_ok, x509ctx, &tls_in,
1147 &server_verify_callback_called, &server_verify_optional);
1153 /* This gets called *by* the dane library verify callback, which interposes
1157 verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
1159 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
1161 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
1162 #ifndef DISABLE_EVENT
1163 BOOL dummy_called, optional = FALSE;
1166 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
1168 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
1169 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1170 deliver_host_address);
1173 dn[sizeof(dn)-1] = '\0';
1175 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
1176 preverify_ok ? "ok":"BAD", depth, dn);
1178 #ifndef DISABLE_EVENT
1179 if (verify_event(&tls_out, cert, depth, dn,
1180 &dummy_called, &optional, US"DANE"))
1181 return 0; /* reject, with peercert set */
1184 if (preverify_ok == 1)
1186 tls_out.dane_verified = TRUE;
1187 #ifndef DISABLE_OCSP
1188 if (client_static_state->u_ocsp.client.verify_store)
1189 { /* client, wanting stapling */
1190 /* Add the server cert's signing chain as the one
1191 for the verification of the OCSP stapled information. */
1193 if (!X509_STORE_add_cert(client_static_state->u_ocsp.client.verify_store,
1196 sk_X509_push(client_static_state->verify_stack, cert);
1202 int err = X509_STORE_CTX_get_error(x509ctx);
1204 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
1205 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
1208 return preverify_ok;
1211 #endif /*SUPPORT_DANE*/
1214 #ifndef DISABLE_OCSP
1215 /*************************************************
1216 * Load OCSP information into state *
1217 *************************************************/
1218 /* Called to load the server OCSP response from the given file into memory, once
1219 caller has determined this is needed. Checks validity. Debugs a message
1222 ASSUMES: single response, for single cert.
1225 state various parts of session state
1226 filename the filename putatively holding an OCSP response
1227 is_pem file is PEM format; otherwise is DER
1231 ocsp_load_response(exim_openssl_state_st * state, const uschar * filename,
1235 OCSP_RESPONSE * resp;
1236 OCSP_BASICRESP * basic_response;
1237 OCSP_SINGLERESP * single_response;
1238 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
1239 STACK_OF(X509) * sk;
1240 unsigned long verify_flags;
1241 int status, reason, i;
1244 debug_printf("tls_ocsp_file (%s) '%s'\n", is_pem ? "PEM" : "DER", filename);
1246 if (!(bio = BIO_new_file(CS filename, "rb")))
1248 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
1255 uschar * data, * freep;
1258 if (!PEM_read_bio(bio, &dummy, &dummy, &data, &len))
1260 DEBUG(D_tls) debug_printf("Failed to read PEM file \"%s\"\n",
1265 resp = d2i_OCSP_RESPONSE(NULL, CUSS &data, len);
1266 OPENSSL_free(freep);
1269 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
1274 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
1278 if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
1280 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
1281 OCSP_response_status_str(status), status);
1287 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1288 OCSP_RESPONSE_print(bp, resp, 0); /* extreme debug: stapling content */
1293 if (!(basic_response = OCSP_response_get1_basic(resp)))
1296 debug_printf("OCSP response parse error: unable to extract basic response.\n");
1300 sk = state->verify_stack;
1301 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
1303 /* May need to expose ability to adjust those flags?
1304 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
1305 OCSP_TRUSTOTHER OCSP_NOINTERN */
1307 /* This does a full verify on the OCSP proof before we load it for serving
1308 up; possibly overkill - just date-checks might be nice enough.
1310 OCSP_basic_verify takes a "store" arg, but does not
1311 use it for the chain verification, which is all we do
1312 when OCSP_NOVERIFY is set. The content from the wire
1313 "basic_response" and a cert-stack "sk" are all that is used.
1315 We have a stack, loaded in setup_certs() if tls_verify_certificates
1316 was a file (not a directory, or "system"). It is unfortunate we
1317 cannot used the connection context store, as that would neatly
1318 handle the "system" case too, but there seems to be no library
1319 function for getting a stack from a store.
1320 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
1321 We do not free the stack since it could be needed a second time for
1324 Separately we might try to replace using OCSP_basic_verify() - which seems to not
1325 be a public interface into the OpenSSL library (there's no manual entry) -
1326 But what with? We also use OCSP_basic_verify in the client stapling callback.
1327 And there we NEED it; we must verify that status... unless the
1328 library does it for us anyway? */
1330 if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0)
1334 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1335 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
1340 /* Here's the simplifying assumption: there's only one response, for the
1341 one certificate we use, and nothing for anything else in a chain. If this
1342 proves false, we need to extract a cert id from our issued cert
1343 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
1344 right cert in the stack and then calls OCSP_single_get0_status()).
1346 I'm hoping to avoid reworking a bunch more of how we handle state here.
1348 XXX that will change when we add support for (TLS1.3) whole-chain stapling
1351 if (!(single_response = OCSP_resp_get0(basic_response, 0)))
1354 debug_printf("Unable to get first response from OCSP basic response.\n");
1358 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
1359 if (status != V_OCSP_CERTSTATUS_GOOD)
1361 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
1362 OCSP_cert_status_str(status), status,
1363 OCSP_crl_reason_str(reason), reason);
1367 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1369 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
1374 /* Add the resp to the list used by tls_server_stapling_cb() */
1376 ocsp_resplist ** op = &state->u_ocsp.server.olist, * oentry;
1377 while (oentry = *op)
1379 *op = oentry = store_get(sizeof(ocsp_resplist), FALSE);
1380 oentry->next = NULL;
1381 oentry->resp = resp;
1386 if (f.running_in_test_harness)
1388 extern char ** environ;
1389 if (environ) for (uschar ** p = USS environ; *p; p++)
1390 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1392 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
1393 goto supply_response;
1401 ocsp_free_response_list(exim_openssl_state_st * cbinfo)
1403 for (ocsp_resplist * olist = cbinfo->u_ocsp.server.olist; olist;
1404 olist = olist->next)
1405 OCSP_RESPONSE_free(olist->resp);
1406 cbinfo->u_ocsp.server.olist = NULL;
1408 #endif /*!DISABLE_OCSP*/
1415 tls_add_certfile(SSL_CTX * sctx, exim_openssl_state_st * cbinfo, uschar * file,
1418 DEBUG(D_tls) debug_printf("tls_certificate file '%s'\n", file);
1419 if (!SSL_CTX_use_certificate_chain_file(sctx, CS file))
1420 return tls_error(string_sprintf(
1421 "SSL_CTX_use_certificate_chain_file file=%s", file),
1422 cbinfo->host, NULL, errstr);
1427 tls_add_pkeyfile(SSL_CTX * sctx, exim_openssl_state_st * cbinfo, uschar * file,
1430 DEBUG(D_tls) debug_printf("tls_privatekey file '%s'\n", file);
1431 if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM))
1432 return tls_error(string_sprintf(
1433 "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr);
1440 /* Called once during tls_init and possibly again during TLS setup, for a
1441 new context, if Server Name Indication was used and tls_sni was seen in
1442 the certificate string.
1445 sctx the SSL_CTX* to update
1446 state various parts of session state
1447 errstr error string pointer
1449 Returns: OK/DEFER/FAIL
1453 tls_expand_session_files(SSL_CTX * sctx, exim_openssl_state_st * state,
1458 if (!state->certificate)
1460 if (!state->is_server) /* client */
1463 if (tls_install_selfsign(sctx, errstr) != OK)
1470 if ( !reexpand_tls_files_for_sni
1471 && ( Ustrstr(state->certificate, US"tls_sni")
1472 || Ustrstr(state->certificate, US"tls_in_sni")
1473 || Ustrstr(state->certificate, US"tls_out_sni")
1475 reexpand_tls_files_for_sni = TRUE;
1477 if (!expand_check(state->certificate, US"tls_certificate", &expanded, errstr))
1481 if (state->is_server)
1483 const uschar * file_list = expanded;
1486 #ifndef DISABLE_OCSP
1487 const uschar * olist = state->u_ocsp.server.file;
1490 BOOL fmt_pem = FALSE;
1493 if (!expand_check(olist, US"tls_ocsp_file", USS &olist, errstr))
1495 if (olist && !*olist)
1498 if ( state->u_ocsp.server.file_expanded && olist
1499 && (Ustrcmp(olist, state->u_ocsp.server.file_expanded) == 0))
1501 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
1506 ocsp_free_response_list(state);
1507 state->u_ocsp.server.file_expanded = olist;
1511 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1513 if ((err = tls_add_certfile(sctx, state, file, errstr)))
1516 #ifndef DISABLE_OCSP
1518 if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1520 if (Ustrncmp(ofile, US"PEM ", 4) == 0)
1525 else if (Ustrncmp(ofile, US"DER ", 4) == 0)
1530 ocsp_load_response(state, ofile, fmt_pem);
1533 DEBUG(D_tls) debug_printf("ran out of ocsp file list\n");
1537 else /* would there ever be a need for multiple client certs? */
1538 if ((err = tls_add_certfile(sctx, state, expanded, errstr)))
1541 if ( state->privatekey
1542 && !expand_check(state->privatekey, US"tls_privatekey", &expanded, errstr))
1545 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1546 of the expansion is an empty string, ignore it also, and assume the private
1547 key is in the same file as the certificate. */
1549 if (expanded && *expanded)
1550 if (state->is_server)
1552 const uschar * file_list = expanded;
1556 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1557 if ((err = tls_add_pkeyfile(sctx, state, file, errstr)))
1560 else /* would there ever be a need for multiple client certs? */
1561 if ((err = tls_add_pkeyfile(sctx, state, expanded, errstr)))
1571 /**************************************************
1572 * One-time init credentials for server and client *
1573 **************************************************/
1576 server_load_ciphers(SSL_CTX * ctx, exim_openssl_state_st * state,
1577 uschar * ciphers, uschar ** errstr)
1579 for (uschar * s = ciphers; *s; s++ ) if (*s == '_') *s = '-';
1580 DEBUG(D_tls) debug_printf("required ciphers: %s\n", ciphers);
1581 if (!SSL_CTX_set_cipher_list(ctx, CS ciphers))
1582 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
1583 state->server_cipher_list = ciphers;
1590 lib_ctx_new(SSL_CTX ** ctxp, host_item * host, uschar ** errstr)
1593 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1594 if (!(ctx = SSL_CTX_new(host ? TLS_client_method() : TLS_server_method())))
1596 if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
1598 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
1600 /* Set up the information callback, which outputs if debugging is at a suitable
1605 SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
1606 #if defined(EXIM_HAVE_OPESSL_TRACE) && !defined(OPENSSL_NO_SSL_TRACE)
1607 /* this needs a debug build of OpenSSL */
1608 SSL_CTX_set_msg_callback(ctx, (void (*)())SSL_trace);
1610 #ifdef OPENSSL_HAVE_KEYLOG_CB
1611 SSL_CTX_set_keylog_callback(ctx, (void (*)())keylog_callback);
1615 /* Automatically re-try reads/writes after renegotiation. */
1616 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
1623 tls_server_creds_init(void)
1626 uschar * dummy_errstr;
1630 state_server.lib_state = null_tls_preload;
1632 if (lib_ctx_new(&ctx, NULL, &dummy_errstr) != OK)
1634 state_server.lib_state.lib_ctx = ctx;
1636 /* Preload DH params and EC curve */
1638 if (opt_unset_or_noexpand(tls_dhparam))
1640 DEBUG(D_tls) debug_printf("TLS: preloading DH params for server\n");
1641 if (init_dh(ctx, tls_dhparam, NULL, &dummy_errstr))
1642 state_server.lib_state.dh = TRUE;
1644 if (opt_unset_or_noexpand(tls_eccurve))
1646 DEBUG(D_tls) debug_printf("TLS: preloading ECDH curve for server\n");
1647 if (init_ecdh(ctx, NULL, &dummy_errstr))
1648 state_server.lib_state.ecdh = TRUE;
1651 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1652 /* If we can, preload the server-side cert, key and ocsp */
1654 if ( opt_set_and_noexpand(tls_certificate)
1655 # ifndef DISABLE_OCSP
1656 && opt_unset_or_noexpand(tls_ocsp_file)
1658 && opt_unset_or_noexpand(tls_privatekey))
1660 /* Set watches on the filenames. The implementation does de-duplication
1661 so we can just blindly do them all. */
1663 if ( tls_set_watch(tls_certificate, TRUE)
1664 # ifndef DISABLE_OCSP
1665 && tls_set_watch(tls_ocsp_file, TRUE)
1667 && tls_set_watch(tls_privatekey, TRUE))
1669 state_server.certificate = tls_certificate;
1670 state_server.privatekey = tls_privatekey;
1671 #ifndef DISABLE_OCSP
1672 state_server.u_ocsp.server.file = tls_ocsp_file;
1675 DEBUG(D_tls) debug_printf("TLS: preloading server certs\n");
1676 if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
1677 state_server.lib_state.conn_certs = TRUE;
1681 DEBUG(D_tls) debug_printf("TLS: not preloading server certs\n");
1684 /* If we can, preload the Authorities for checking client certs against.
1685 Actual choice to do verify is made (tls_{,try_}verify_hosts)
1686 at TLS conn startup */
1688 if ( opt_set_and_noexpand(tls_verify_certificates)
1689 && opt_unset_or_noexpand(tls_crl))
1691 /* Watch the default dir also as they are always included */
1693 if ( tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
1694 && tls_set_watch(tls_verify_certificates, FALSE)
1695 && tls_set_watch(tls_crl, FALSE))
1697 DEBUG(D_tls) debug_printf("TLS: preloading CA bundle for server\n");
1699 if (setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, &dummy_errstr)
1701 state_server.lib_state.cabundle = TRUE;
1705 DEBUG(D_tls) debug_printf("TLS: not preloading CA bundle for server\n");
1706 #endif /* EXIM_HAVE_INOTIFY */
1709 /* If we can, preload the ciphers control string */
1711 if (opt_set_and_noexpand(tls_require_ciphers))
1713 DEBUG(D_tls) debug_printf("TLS: preloading cipher list for server\n");
1714 if (server_load_ciphers(ctx, &state_server, tls_require_ciphers,
1715 &dummy_errstr) == OK)
1716 state_server.lib_state.pri_string = TRUE;
1719 DEBUG(D_tls) debug_printf("TLS: not preloading cipher list for server\n");
1725 /* Preload whatever creds are static, onto a transport. The client can then
1726 just copy the pointer as it starts up.
1727 Called from the daemon after a cache-invalidate with watch set; called from
1728 a queue-run startup with watch clear. */
1731 tls_client_creds_init(transport_instance * t, BOOL watch)
1733 smtp_transport_options_block * ob = t->options_block;
1734 exim_openssl_state_st tpt_dummy_state;
1735 host_item * dummy_host = (host_item *)1;
1736 uschar * dummy_errstr;
1741 ob->tls_preload = null_tls_preload;
1742 if (lib_ctx_new(&ctx, dummy_host, &dummy_errstr) != OK)
1744 ob->tls_preload.lib_ctx = ctx;
1746 tpt_dummy_state.lib_state = ob->tls_preload;
1748 if (opt_unset_or_noexpand(tls_dhparam))
1750 DEBUG(D_tls) debug_printf("TLS: preloading DH params for transport '%s'\n", t->name);
1751 if (init_dh(ctx, tls_dhparam, NULL, &dummy_errstr))
1752 ob->tls_preload.dh = TRUE;
1754 if (opt_unset_or_noexpand(tls_eccurve))
1756 DEBUG(D_tls) debug_printf("TLS: preloading ECDH curve for transport '%s'\n", t->name);
1757 if (init_ecdh(ctx, NULL, &dummy_errstr))
1758 ob->tls_preload.ecdh = TRUE;
1761 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1762 if ( opt_set_and_noexpand(ob->tls_certificate)
1763 && opt_unset_or_noexpand(ob->tls_privatekey))
1766 || ( tls_set_watch(ob->tls_certificate, FALSE)
1767 && tls_set_watch(ob->tls_privatekey, FALSE)
1770 uschar * pkey = ob->tls_privatekey;
1773 debug_printf("TLS: preloading client certs for transport '%s'\n",t->name);
1775 if ( tls_add_certfile(ctx, &tpt_dummy_state, ob->tls_certificate,
1777 && tls_add_pkeyfile(ctx, &tpt_dummy_state,
1778 pkey ? pkey : ob->tls_certificate,
1781 ob->tls_preload.conn_certs = TRUE;
1786 debug_printf("TLS: not preloading client certs, for transport '%s'\n", t->name);
1789 if ( opt_set_and_noexpand(ob->tls_verify_certificates)
1790 && opt_unset_or_noexpand(ob->tls_crl))
1793 || tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
1794 && tls_set_watch(ob->tls_verify_certificates, FALSE)
1795 && tls_set_watch(ob->tls_crl, FALSE)
1799 debug_printf("TLS: preloading CA bundle for transport '%s'\n", t->name);
1801 if (setup_certs(ctx, ob->tls_verify_certificates,
1802 ob->tls_crl, dummy_host, &dummy_errstr) == OK)
1803 ob->tls_preload.cabundle = TRUE;
1808 debug_printf("TLS: not preloading CA bundle, for transport '%s'\n", t->name);
1810 #endif /*EXIM_HAVE_INOTIFY*/
1814 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1815 /* Invalidate the creds cached, by dropping the current ones.
1816 Call when we notice one of the source files has changed. */
1819 tls_server_creds_invalidate(void)
1821 SSL_CTX_free(state_server.lib_state.lib_ctx);
1822 state_server.lib_state = null_tls_preload;
1827 tls_client_creds_invalidate(transport_instance * t)
1829 smtp_transport_options_block * ob = t->options_block;
1830 SSL_CTX_free(ob->tls_preload.lib_ctx);
1831 ob->tls_preload = null_tls_preload;
1837 tls_server_creds_invalidate(void)
1841 tls_client_creds_invalidate(transport_instance * t)
1844 #endif /*EXIM_HAVE_INOTIFY*/
1848 #ifndef DISABLE_OCSP
1850 x509_store_dump_cert_s_names(X509_STORE * store)
1852 STACK_OF(X509_OBJECT) * roots= store->objs;
1853 static uschar name[256];
1855 for (int i= 0; i < sk_X509_OBJECT_num(roots); i++)
1857 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
1858 if(tmp_obj->type == X509_LU_X509)
1860 X509_NAME * sn = X509_get_subject_name(tmp_obj->data.x509);
1861 if (X509_NAME_oneline(sn, CS name, sizeof(name)))
1863 name[sizeof(name)-1] = '\0';
1864 debug_printf(" %s\n", name);
1873 #ifndef DISABLE_TLS_RESUME
1874 /* Manage the keysets used for encrypting the session tickets, on the server. */
1876 typedef struct { /* Session ticket encryption key */
1879 const EVP_CIPHER * aes_cipher;
1880 uschar aes_key[32]; /* size needed depends on cipher. aes_128 implies 128/8 = 16? */
1881 const EVP_MD * hmac_hash;
1882 uschar hmac_key[16];
1887 static exim_stek exim_tk; /* current key */
1888 static exim_stek exim_tk_old; /* previous key */
1893 time_t t = time(NULL);
1895 if (exim_tk.name[0])
1897 if (exim_tk.renew >= t) return;
1898 exim_tk_old = exim_tk;
1901 if (f.running_in_test_harness) ssl_session_timeout = 6;
1903 DEBUG(D_tls) debug_printf("OpenSSL: %s STEK\n", exim_tk.name[0] ? "rotating" : "creating");
1904 if (RAND_bytes(exim_tk.aes_key, sizeof(exim_tk.aes_key)) <= 0) return;
1905 if (RAND_bytes(exim_tk.hmac_key, sizeof(exim_tk.hmac_key)) <= 0) return;
1906 if (RAND_bytes(exim_tk.name+1, sizeof(exim_tk.name)-1) <= 0) return;
1908 exim_tk.name[0] = 'E';
1909 exim_tk.aes_cipher = EVP_aes_256_cbc();
1910 exim_tk.hmac_hash = EVP_sha256();
1911 exim_tk.expire = t + ssl_session_timeout;
1912 exim_tk.renew = t + ssl_session_timeout/2;
1918 if (!exim_tk.name[0]) return NULL;
1923 tk_find(const uschar * name)
1925 return memcmp(name, exim_tk.name, sizeof(exim_tk.name)) == 0 ? &exim_tk
1926 : memcmp(name, exim_tk_old.name, sizeof(exim_tk_old.name)) == 0 ? &exim_tk_old
1930 /* Callback for session tickets, on server */
1932 ticket_key_callback(SSL * ssl, uschar key_name[16],
1933 uschar * iv, EVP_CIPHER_CTX * c_ctx, HMAC_CTX * hctx, int enc)
1935 tls_support * tlsp = state_server.tlsp;
1940 DEBUG(D_tls) debug_printf("ticket_key_callback: create new session\n");
1941 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
1943 if (RAND_bytes(iv, EVP_MAX_IV_LENGTH) <= 0)
1944 return -1; /* insufficient random */
1946 if (!(key = tk_current())) /* current key doesn't exist or isn't valid */
1947 return 0; /* key couldn't be created */
1948 memcpy(key_name, key->name, 16);
1949 DEBUG(D_tls) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - time(NULL));
1951 /*XXX will want these dependent on the ssl session strength */
1952 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
1953 key->hmac_hash, NULL);
1954 EVP_EncryptInit_ex(c_ctx, key->aes_cipher, NULL, key->aes_key, iv);
1956 DEBUG(D_tls) debug_printf("ticket created\n");
1961 time_t now = time(NULL);
1963 DEBUG(D_tls) debug_printf("ticket_key_callback: retrieve session\n");
1964 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
1966 if (!(key = tk_find(key_name)) || key->expire < now)
1970 debug_printf("ticket not usable (%s)\n", key ? "expired" : "not found");
1971 if (key) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - now);
1976 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
1977 key->hmac_hash, NULL);
1978 EVP_DecryptInit_ex(c_ctx, key->aes_cipher, NULL, key->aes_key, iv);
1980 DEBUG(D_tls) debug_printf("ticket usable, STEK expire " TIME_T_FMT "\n", key->expire - now);
1982 /* The ticket lifetime and renewal are the same as the STEK lifetime and
1983 renewal, which is overenthusiastic. A factor of, say, 3x longer STEK would
1984 be better. To do that we'd have to encode ticket lifetime in the name as
1985 we don't yet see the restored session. Could check posthandshake for TLS1.3
1986 and trigger a new ticket then, but cannot do that for TLS1.2 */
1987 return key->renew < now ? 2 : 1;
1995 setup_cert_verify(SSL_CTX * ctx, BOOL optional,
1996 int (*cert_vfy_cb)(int, X509_STORE_CTX *))
1998 /* If verification is optional, don't fail if no certificate */
2000 SSL_CTX_set_verify(ctx,
2001 SSL_VERIFY_PEER | (optional ? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
2006 /*************************************************
2007 * Callback to handle SNI *
2008 *************************************************/
2010 /* Called when acting as server during the TLS session setup if a Server Name
2011 Indication extension was sent by the client.
2013 API documentation is OpenSSL s_server.c implementation.
2016 s SSL* of the current session
2017 ad unknown (part of OpenSSL API) (unused)
2018 arg Callback of "our" registered data
2020 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
2022 XXX might need to change to using ClientHello callback,
2023 per https://www.openssl.org/docs/manmaster/man3/SSL_client_hello_cb_fn.html
2026 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2028 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
2030 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
2031 exim_openssl_state_st *state = (exim_openssl_state_st *) arg;
2033 int old_pool = store_pool;
2034 uschar * dummy_errstr;
2037 return SSL_TLSEXT_ERR_OK;
2039 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
2040 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
2042 /* Make the extension value available for expansion */
2043 store_pool = POOL_PERM;
2044 tls_in.sni = string_copy_taint(US servername, TRUE);
2045 store_pool = old_pool;
2047 if (!reexpand_tls_files_for_sni)
2048 return SSL_TLSEXT_ERR_OK;
2050 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
2051 not confident that memcpy wouldn't break some internal reference counting.
2052 Especially since there's a references struct member, which would be off. */
2054 if (lib_ctx_new(&server_sni, NULL, &dummy_errstr) != OK)
2057 /* Not sure how many of these are actually needed, since SSL object
2058 already exists. Might even need this selfsame callback, for reneg? */
2061 SSL_CTX * ctx = state_server.lib_state.lib_ctx;
2062 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(ctx));
2063 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(ctx));
2064 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(ctx));
2065 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(ctx));
2066 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
2067 SSL_CTX_set_tlsext_servername_arg(server_sni, state);
2070 if ( !init_dh(server_sni, state->dhparam, NULL, &dummy_errstr)
2071 || !init_ecdh(server_sni, NULL, &dummy_errstr)
2075 if ( state->server_cipher_list
2076 && !SSL_CTX_set_cipher_list(server_sni, CS state->server_cipher_list))
2079 #ifndef DISABLE_OCSP
2080 if (state->u_ocsp.server.file)
2082 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
2083 SSL_CTX_set_tlsext_status_arg(server_sni, state);
2089 if ( !expand_check(tls_verify_certificates, US"tls_verify_certificates",
2090 &expcerts, &dummy_errstr)
2091 || (rc = setup_certs(server_sni, expcerts, tls_crl, NULL,
2092 &dummy_errstr)) != OK)
2095 if (expcerts && *expcerts)
2096 setup_cert_verify(server_sni, FALSE, verify_callback_server);
2099 /* do this after setup_certs, because this can require the certs for verifying
2100 OCSP information. */
2101 if ((rc = tls_expand_session_files(server_sni, state, &dummy_errstr)) != OK)
2104 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
2105 SSL_set_SSL_CTX(s, server_sni);
2106 return SSL_TLSEXT_ERR_OK;
2108 bad: return SSL_TLSEXT_ERR_ALERT_FATAL;
2110 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
2115 #ifndef DISABLE_OCSP
2117 /*************************************************
2118 * Callback to handle OCSP Stapling *
2119 *************************************************/
2121 /* Called when acting as server during the TLS session setup if the client
2122 requests OCSP information with a Certificate Status Request.
2124 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
2130 tls_server_stapling_cb(SSL *s, void *arg)
2132 const exim_openssl_state_st * state = arg;
2133 ocsp_resplist * olist = state->u_ocsp.server.olist;
2134 uschar * response_der; /*XXX blob */
2135 int response_der_len;
2138 debug_printf("Received TLS status request (OCSP stapling); %s response list\n",
2139 olist ? "have" : "lack");
2141 tls_in.ocsp = OCSP_NOT_RESP;
2143 return SSL_TLSEXT_ERR_NOACK;
2145 #ifdef EXIM_HAVE_OPESSL_GET0_SERIAL
2147 const X509 * cert_sent = SSL_get_certificate(s);
2148 const ASN1_INTEGER * cert_serial = X509_get0_serialNumber(cert_sent);
2149 const BIGNUM * cert_bn = ASN1_INTEGER_to_BN(cert_serial, NULL);
2150 const X509_NAME * cert_issuer = X509_get_issuer_name(cert_sent);
2154 for (; olist; olist = olist->next)
2156 OCSP_BASICRESP * bs = OCSP_response_get1_basic(olist->resp);
2157 const OCSP_SINGLERESP * single = OCSP_resp_get0(bs, 0);
2158 const OCSP_CERTID * cid = OCSP_SINGLERESP_get0_id(single);
2159 ASN1_INTEGER * res_cert_serial;
2160 const BIGNUM * resp_bn;
2161 ASN1_OCTET_STRING * res_cert_iNameHash;
2164 (void) OCSP_id_get0_info(&res_cert_iNameHash, NULL, NULL, &res_cert_serial,
2165 (OCSP_CERTID *) cid);
2166 resp_bn = ASN1_INTEGER_to_BN(res_cert_serial, NULL);
2170 debug_printf("cert serial: %s\n", BN_bn2hex(cert_bn));
2171 debug_printf("resp serial: %s\n", BN_bn2hex(resp_bn));
2174 if (BN_cmp(cert_bn, resp_bn) == 0)
2176 DEBUG(D_tls) debug_printf("matched serial for ocsp\n");
2178 /*XXX TODO: check the rest of the list for duplicate matches.
2179 If any, need to also check the Issuer Name hash.
2180 Without this, we will provide the wrong status in the case of
2185 DEBUG(D_tls) debug_printf("not match serial for ocsp\n");
2189 DEBUG(D_tls) debug_printf("failed to find match for ocsp\n");
2190 return SSL_TLSEXT_ERR_NOACK;
2196 DEBUG(D_tls) debug_printf("OpenSSL version too early to support multi-leaf OCSP\n");
2197 return SSL_TLSEXT_ERR_NOACK;
2201 /*XXX could we do the i2d earlier, rather than during the callback? */
2202 response_der = NULL;
2203 response_der_len = i2d_OCSP_RESPONSE(olist->resp, &response_der);
2204 if (response_der_len <= 0)
2205 return SSL_TLSEXT_ERR_NOACK;
2207 SSL_set_tlsext_status_ocsp_resp(state_server.lib_state.lib_ssl,
2208 response_der, response_der_len);
2209 tls_in.ocsp = OCSP_VFIED;
2210 return SSL_TLSEXT_ERR_OK;
2215 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
2217 BIO_printf(bp, "\t%s: ", str);
2218 ASN1_GENERALIZEDTIME_print(bp, time);
2223 tls_client_stapling_cb(SSL *s, void *arg)
2225 exim_openssl_state_st * cbinfo = arg;
2226 const unsigned char * p;
2228 OCSP_RESPONSE * rsp;
2229 OCSP_BASICRESP * bs;
2232 DEBUG(D_tls) debug_printf("Received TLS status callback (OCSP stapling):\n");
2233 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
2236 /* Expect this when we requested ocsp but got none */
2237 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
2238 log_write(0, LOG_MAIN, "Required TLS certificate status not received");
2240 DEBUG(D_tls) debug_printf(" null\n");
2241 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2244 if (!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
2246 tls_out.ocsp = OCSP_FAILED; /*XXX should use tlsp-> to permit concurrent outbound */
2247 if (LOGGING(tls_cipher))
2248 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
2250 DEBUG(D_tls) debug_printf(" parse error\n");
2254 if (!(bs = OCSP_response_get1_basic(rsp)))
2256 tls_out.ocsp = OCSP_FAILED;
2257 if (LOGGING(tls_cipher))
2258 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
2260 DEBUG(D_tls) debug_printf(" error parsing response\n");
2261 OCSP_RESPONSE_free(rsp);
2265 /* We'd check the nonce here if we'd put one in the request. */
2266 /* However that would defeat cacheability on the server so we don't. */
2268 /* This section of code reworked from OpenSSL apps source;
2269 The OpenSSL Project retains copyright:
2270 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
2274 #ifndef EXIM_HAVE_OCSP_RESP_COUNT
2275 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
2278 DEBUG(D_tls) bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
2280 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
2282 /* Use the chain that verified the server cert to verify the stapled info */
2283 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
2285 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
2286 cbinfo->u_ocsp.client.verify_store, OCSP_NOEXPLICIT)) <= 0)
2287 if (ERR_peek_error())
2289 tls_out.ocsp = OCSP_FAILED;
2290 if (LOGGING(tls_cipher)) log_write(0, LOG_MAIN,
2291 "Received TLS cert status response, itself unverifiable: %s",
2292 ERR_reason_error_string(ERR_peek_error()));
2293 BIO_printf(bp, "OCSP response verify failure\n");
2294 ERR_print_errors(bp);
2295 OCSP_RESPONSE_print(bp, rsp, 0);
2299 DEBUG(D_tls) debug_printf("no explicit trust for OCSP signing"
2300 " in the root CA certificate; ignoring\n");
2302 DEBUG(D_tls) debug_printf("OCSP response well-formed and signed OK\n");
2304 /*XXX So we have a good stapled OCSP status. How do we know
2305 it is for the cert of interest? OpenSSL 1.1.0 has a routine
2306 OCSP_resp_find_status() which matches on a cert id, which presumably
2307 we should use. Making an id needs OCSP_cert_id_new(), which takes
2308 issuerName, issuerKey, serialNumber. Are they all in the cert?
2310 For now, carry on blindly accepting the resp. */
2313 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
2314 OCSP_resp_count(bs) - 1;
2316 sk_OCSP_SINGLERESP_num(sresp) - 1;
2320 OCSP_SINGLERESP * single = OCSP_resp_get0(bs, idx);
2322 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
2324 /*XXX so I can see putting a loop in here to handle a rsp with >1 singleresp
2325 - but what happens with a GnuTLS-style input?
2327 we could do with a debug label for each singleresp
2328 - it has a certID with a serialNumber, but I see no API to get that
2330 status = OCSP_single_get0_status(single, &reason, &rev,
2331 &thisupd, &nextupd);
2333 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
2334 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
2335 if (!OCSP_check_validity(thisupd, nextupd,
2336 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
2338 tls_out.ocsp = OCSP_FAILED;
2339 DEBUG(D_tls) ERR_print_errors(bp);
2340 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
2344 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
2345 OCSP_cert_status_str(status));
2348 case V_OCSP_CERTSTATUS_GOOD:
2349 continue; /* the idx loop */
2350 case V_OCSP_CERTSTATUS_REVOKED:
2351 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
2352 reason != -1 ? "; reason: " : "",
2353 reason != -1 ? OCSP_crl_reason_str(reason) : "");
2354 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
2357 log_write(0, LOG_MAIN,
2358 "Server certificate status unknown, in OCSP stapling");
2366 tls_out.ocsp = OCSP_VFIED;
2370 tls_out.ocsp = OCSP_FAILED;
2371 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2376 OCSP_RESPONSE_free(rsp);
2379 #endif /*!DISABLE_OCSP*/
2382 /*************************************************
2383 * Initialize for TLS *
2384 *************************************************/
2385 /* Called from both server and client code, to do preliminary initialization
2386 of the library. We allocate and return a context structure.
2389 host connected host, if client; NULL if server
2390 ob transport options block, if client; NULL if server
2391 ocsp_file file of stapling info (server); flag for require ocsp (client)
2392 addr address if client; NULL if server (for some randomness)
2393 caller_state place to put pointer to allocated state-struct
2394 errstr error string pointer
2396 Returns: OK/DEFER/FAIL
2400 tls_init(host_item * host, smtp_transport_options_block * ob,
2401 #ifndef DISABLE_OCSP
2404 address_item *addr, exim_openssl_state_st ** caller_state,
2409 exim_openssl_state_st * state;
2412 if (host) /* client */
2414 state = store_malloc(sizeof(exim_openssl_state_st));
2415 memset(state, 0, sizeof(*state));
2416 state->certificate = ob->tls_certificate;
2417 state->privatekey = ob->tls_privatekey;
2418 state->is_server = FALSE;
2419 state->dhparam = NULL;
2420 state->lib_state = ob->tls_preload;
2424 state = &state_server;
2425 state->certificate = tls_certificate;
2426 state->privatekey = tls_privatekey;
2427 state->is_server = TRUE;
2428 state->dhparam = tls_dhparam;
2429 state->lib_state = state_server.lib_state;
2435 if (!state->lib_state.pri_string)
2436 state->server_cipher_list = NULL;
2438 #ifndef DISABLE_EVENT
2439 state->event_action = NULL;
2444 /* It turns out that we need to seed the random number generator this early in
2445 order to get the full complement of ciphers to work. It took me roughly a day
2446 of work to discover this by experiment.
2448 On systems that have /dev/urandom, SSL may automatically seed itself from
2449 there. Otherwise, we have to make something up as best we can. Double check
2452 Although we likely called this before, at daemon startup, this is a chance
2453 to mix in further variable info (time, pid) if needed. */
2455 if (!lib_rand_init(addr))
2456 return tls_error(US"RAND_status", host,
2457 US"unable to seed random number generator", errstr);
2459 /* Apply administrator-supplied work-arounds.
2460 Historically we applied just one requested option,
2461 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
2462 moved to an administrator-controlled list of options to specify and
2463 grandfathered in the first one as the default value for "openssl_options".
2465 No OpenSSL version number checks: the options we accept depend upon the
2466 availability of the option value macros from OpenSSL. */
2469 if (!tls_openssl_options_parse(openssl_options, &init_options))
2470 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
2472 /* Create a context.
2473 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
2474 negotiation in the different methods; as far as I can tell, the only
2475 *_{server,client}_method which allows negotiation is SSLv23, which exists even
2476 when OpenSSL is built without SSLv2 support.
2477 By disabling with openssl_options, we can let admins re-enable with the
2480 if (!(ctx = state->lib_state.lib_ctx))
2482 if ((rc = lib_ctx_new(&ctx, host, errstr)) != OK)
2484 state->lib_state.lib_ctx = ctx;
2487 #ifndef DISABLE_TLS_RESUME
2488 tlsp->resumption = RESUME_SUPPORTED;
2492 #ifndef DISABLE_TLS_RESUME
2493 /* Should the server offer session resumption? */
2494 if (!host && verify_check_host(&tls_resumption_hosts) == OK)
2496 DEBUG(D_tls) debug_printf("tls_resumption_hosts overrides openssl_options\n");
2497 init_options &= ~SSL_OP_NO_TICKET;
2498 tlsp->resumption |= RESUME_SERVER_TICKET; /* server will give ticket on request */
2499 tlsp->host_resumable = TRUE;
2503 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
2504 if (!(SSL_CTX_set_options(ctx, init_options)))
2505 return tls_error(string_sprintf(
2506 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
2509 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
2511 /* We'd like to disable session cache unconditionally, but foolish Outlook
2512 Express clients then give up the first TLS connection and make a second one
2513 (which works). Only when there is an IMAP service on the same machine.
2514 Presumably OE is trying to use the cache for A on B. Leave it enabled for
2515 now, until we work out a decent way of presenting control to the config. It
2516 will never be used because we use a new context every time. */
2518 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
2521 /* Initialize with DH parameters if supplied */
2522 /* Initialize ECDH temp key parameter selection */
2524 if (state->lib_state.dh)
2525 { DEBUG(D_tls) debug_printf("TLS: DH params were preloaded\n"); }
2527 if (!init_dh(ctx, state->dhparam, host, errstr)) return DEFER;
2529 if (state->lib_state.ecdh)
2530 { DEBUG(D_tls) debug_printf("TLS: ECDH curve was preloaded\n"); }
2532 if (!init_ecdh(ctx, host, errstr)) return DEFER;
2534 /* Set up certificate and key (and perhaps OCSP info) */
2536 if (state->lib_state.conn_certs)
2539 debug_printf("TLS: %s certs were preloaded\n", host ? "client":"server");
2543 #ifndef DISABLE_OCSP
2546 state->u_ocsp.server.file = ocsp_file;
2547 state->u_ocsp.server.file_expanded = NULL;
2548 state->u_ocsp.server.olist = NULL;
2551 if ((rc = tls_expand_session_files(ctx, state, errstr)) != OK) return rc;
2554 /* If we need to handle SNI or OCSP, do so */
2556 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2557 # ifndef DISABLE_OCSP
2558 if (!(state->verify_stack = sk_X509_new_null()))
2560 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
2565 if (!host) /* server */
2567 # ifndef DISABLE_OCSP
2568 /* We check u_ocsp.server.file, not server.olist, because we care about if
2569 the option exists, not what the current expansion might be, as SNI might
2570 change the certificate and OCSP file in use between now and the time the
2571 callback is invoked. */
2572 if (state->u_ocsp.server.file)
2574 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
2575 SSL_CTX_set_tlsext_status_arg(ctx, state);
2578 /* We always do this, so that $tls_sni is available even if not used in
2580 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
2581 SSL_CTX_set_tlsext_servername_arg(ctx, state);
2583 # ifndef DISABLE_OCSP
2585 if(ocsp_file) /* wanting stapling */
2587 if (!(state->u_ocsp.client.verify_store = X509_STORE_new()))
2589 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
2592 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
2593 SSL_CTX_set_tlsext_status_arg(ctx, state);
2598 state->verify_cert_hostnames = NULL;
2600 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
2601 /* Set up the RSA callback */
2602 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
2605 /* Finally, set the session cache timeout, and we are done.
2606 The period appears to be also used for (server-generated) session tickets */
2608 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
2609 DEBUG(D_tls) debug_printf("Initialized TLS\n");
2611 *caller_state = state;
2619 /*************************************************
2620 * Get name of cipher in use *
2621 *************************************************/
2624 Argument: pointer to an SSL structure for the connection
2625 pointer to number of bits for cipher
2626 Returns: pointer to allocated string in perm-pool
2630 construct_cipher_name(SSL * ssl, const uschar * ver, int * bits)
2632 int pool = store_pool;
2633 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
2634 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
2635 the accessor functions use const in the prototype. */
2637 const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
2640 SSL_CIPHER_get_bits(c, bits);
2642 store_pool = POOL_PERM;
2643 s = string_sprintf("%s:%s:%u", ver, SSL_CIPHER_get_name(c), *bits);
2645 DEBUG(D_tls) debug_printf("Cipher: %s\n", s);
2650 /* Get IETF-standard name for ciphersuite.
2651 Argument: pointer to an SSL structure for the connection
2652 Returns: pointer to string
2655 static const uschar *
2656 cipher_stdname_ssl(SSL * ssl)
2658 #ifdef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
2659 return CUS SSL_CIPHER_standard_name(SSL_get_current_cipher(ssl));
2661 ushort id = 0xffff & SSL_CIPHER_get_id(SSL_get_current_cipher(ssl));
2662 return cipher_stdname(id >> 8, id & 0xff);
2667 static const uschar *
2668 tlsver_name(SSL * ssl)
2671 int pool = store_pool;
2673 store_pool = POOL_PERM;
2674 s = string_copy(US SSL_get_version(ssl));
2676 if ((p = Ustrchr(s, 'v'))) /* TLSv1.2 -> TLS1.2 */
2677 for (;; p++) if (!(*p = p[1])) break;
2683 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned siz)
2685 /*XXX we might consider a list-of-certs variable for the cert chain.
2686 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
2687 in list-handling functions, also consider the difference between the entire
2688 chain and the elements sent by the peer. */
2690 tlsp->peerdn = NULL;
2692 /* Will have already noted peercert on a verify fail; possibly not the leaf */
2693 if (!tlsp->peercert)
2694 tlsp->peercert = SSL_get_peer_certificate(ssl);
2695 /* Beware anonymous ciphers which lead to server_cert being NULL */
2697 if (!X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, siz))
2698 { DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n"); }
2701 int oldpool = store_pool;
2703 peerdn[siz-1] = '\0'; /* paranoia */
2704 store_pool = POOL_PERM;
2705 tlsp->peerdn = string_copy(peerdn);
2706 store_pool = oldpool;
2708 /* We used to set CV in the cert-verify callbacks (either plain or dane)
2709 but they don't get called on session-resumption. So use the official
2710 interface, which uses the resumed value. Unfortunately this claims verified
2711 when it actually failed but we're in try-verify mode, due to us wanting the
2712 knowlege that it failed so needing to have the callback and forcing a
2713 permissive return. If we don't force it, the TLS startup is failed.
2714 The extra bit of information is set in verify_override in the cb, stashed
2715 for resumption next to the TLS session, and used here. */
2717 if (!tlsp->verify_override)
2718 tlsp->certificate_verified =
2720 tlsp->dane_verified ||
2722 SSL_get_verify_result(ssl) == X509_V_OK;
2730 /*************************************************
2731 * Set up for verifying certificates *
2732 *************************************************/
2734 #ifndef DISABLE_OCSP
2735 /* Load certs from file, return TRUE on success */
2738 chain_from_pem_file(const uschar * file, STACK_OF(X509) * verify_stack)
2743 while (sk_X509_num(verify_stack) > 0)
2744 X509_free(sk_X509_pop(verify_stack));
2746 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
2747 while ((x = PEM_read_bio_X509(bp, NULL, 0, NULL)))
2748 sk_X509_push(verify_stack, x);
2756 /* Called by both client and server startup; on the server possibly
2757 repeated after a Server Name Indication.
2760 sctx SSL_CTX* to initialise
2761 certs certs file, expanded
2762 crl CRL file or NULL
2763 host NULL in a server; the remote host in a client
2764 errstr error string pointer
2766 Returns: OK/DEFER/FAIL
2770 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host,
2773 uschar *expcerts, *expcrl;
2775 if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
2777 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
2779 if (expcerts && *expcerts)
2781 /* Tell the library to use its compiled-in location for the system default
2782 CA bundle. Then add the ones specified in the config, if any. */
2784 if (!SSL_CTX_set_default_verify_paths(sctx))
2785 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
2787 if (Ustrcmp(expcerts, "system") != 0 && Ustrncmp(expcerts, "system,", 7) != 0)
2789 struct stat statbuf;
2791 if (Ustat(expcerts, &statbuf) < 0)
2793 log_write(0, LOG_MAIN|LOG_PANIC,
2794 "failed to stat %s for certificates", expcerts);
2800 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
2801 { file = NULL; dir = expcerts; }
2804 file = expcerts; dir = NULL;
2805 #ifndef DISABLE_OCSP
2806 /* In the server if we will be offering an OCSP proof, load chain from
2807 file for verifying the OCSP proof at load time. */
2809 /*XXX Glitch! The file here is tls_verify_certs: the chain for verifying the client cert.
2810 This is inconsistent with the need to verify the OCSP proof of the server cert.
2814 && statbuf.st_size > 0
2815 && state_server.u_ocsp.server.file
2816 && !chain_from_pem_file(file, state_server.verify_stack)
2819 log_write(0, LOG_MAIN|LOG_PANIC,
2820 "failed to load cert chain from %s", file);
2826 /* If a certificate file is empty, the load function fails with an
2827 unhelpful error message. If we skip it, we get the correct behaviour (no
2828 certificates are recognized, but the error message is still misleading (it
2829 says no certificate was supplied). But this is better. */
2831 if ( (!file || statbuf.st_size > 0)
2832 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
2833 return tls_error(US"SSL_CTX_load_verify_locations",
2834 host, NULL, errstr);
2836 /* On the server load the list of CAs for which we will accept certs, for
2837 sending to the client. This is only for the one-file
2838 tls_verify_certificates variant.
2839 If a list isn't loaded into the server, but some verify locations are set,
2840 the server end appears to make a wildcard request for client certs.
2841 Meanwhile, the client library as default behaviour *ignores* the list
2842 we send over the wire - see man SSL_CTX_set_client_cert_cb.
2843 Because of this, and that the dir variant is likely only used for
2844 the public-CA bundle (not for a private CA), not worth fixing. */
2848 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
2849 int i = sk_X509_NAME_num(names);
2851 if (!host) SSL_CTX_set_client_CA_list(sctx, names);
2852 DEBUG(D_tls) debug_printf("Added %d additional certificate authorit%s\n",
2853 i, i>1 ? "ies":"y");
2857 debug_printf("Added dir for additional certificate authorities\n");
2861 /* Handle a certificate revocation list. */
2863 #if OPENSSL_VERSION_NUMBER > 0x00907000L
2865 /* This bit of code is now the version supplied by Lars Mainka. (I have
2866 merely reformatted it into the Exim code style.)
2868 "From here I changed the code to add support for multiple crl's
2869 in pem format in one file or to support hashed directory entries in
2870 pem format instead of a file. This method now uses the library function
2871 X509_STORE_load_locations to add the CRL location to the SSL context.
2872 OpenSSL will then handle the verify against CA certs and CRLs by
2873 itself in the verify callback." */
2875 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
2876 if (expcrl && *expcrl)
2878 struct stat statbufcrl;
2879 if (Ustat(expcrl, &statbufcrl) < 0)
2881 log_write(0, LOG_MAIN|LOG_PANIC,
2882 "failed to stat %s for certificates revocation lists", expcrl);
2887 /* is it a file or directory? */
2889 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
2890 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
2894 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
2900 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
2902 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
2903 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
2905 /* setting the flags to check against the complete crl chain */
2907 X509_STORE_set_flags(cvstore,
2908 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
2912 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
2920 /*************************************************
2921 * Start a TLS session in a server *
2922 *************************************************/
2923 /* This is called when Exim is running as a server, after having received
2924 the STARTTLS command. It must respond to that command, and then negotiate
2928 errstr pointer to error message
2930 Returns: OK on success
2931 DEFER for errors before the start of the negotiation
2932 FAIL for errors during the negotiation; the server can't
2937 tls_server_start(uschar ** errstr)
2940 uschar * expciphers;
2941 exim_openssl_state_st * dummy_statep;
2944 static uschar peerdn[256];
2946 /* Check for previous activation */
2948 if (tls_in.active.sock >= 0)
2950 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
2951 smtp_printf("554 Already in TLS\r\n", FALSE);
2955 /* Initialize the SSL library. If it fails, it will already have logged
2958 rc = tls_init(NULL, NULL,
2959 #ifndef DISABLE_OCSP
2962 NULL, &dummy_statep, &tls_in, errstr);
2963 if (rc != OK) return rc;
2964 ctx = state_server.lib_state.lib_ctx;
2966 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2967 were historically separated by underscores. So that I can use either form in my
2968 tests, and also for general convenience, we turn underscores into hyphens here.
2970 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
2971 for TLS 1.3 . Since we do not call it at present we get the default list:
2972 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
2975 if (state_server.lib_state.pri_string)
2976 { DEBUG(D_tls) debug_printf("TLS: cipher list was preloaded\n"); }
2979 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
2983 && (rc = server_load_ciphers(ctx, &state_server, expciphers, errstr)) != OK)
2987 /* If this is a host for which certificate verification is mandatory or
2988 optional, set up appropriately. */
2990 tls_in.certificate_verified = FALSE;
2992 tls_in.dane_verified = FALSE;
2994 server_verify_callback_called = FALSE;
2996 if (verify_check_host(&tls_verify_hosts) == OK)
2997 server_verify_optional = FALSE;
2998 else if (verify_check_host(&tls_try_verify_hosts) == OK)
2999 server_verify_optional = TRUE;
3005 if (!expand_check(tls_verify_certificates, US"tls_verify_certificates",
3008 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3010 if (state_server.lib_state.cabundle)
3011 { DEBUG(D_tls) debug_printf("TLS: CA bundle for server was preloaded\n"); }
3013 if ((rc = setup_certs(ctx, expcerts, tls_crl, NULL, errstr)) != OK)
3016 if (expcerts && *expcerts)
3017 setup_cert_verify(ctx, server_verify_optional, verify_callback_server);
3021 #ifndef DISABLE_TLS_RESUME
3022 SSL_CTX_set_tlsext_ticket_key_cb(ctx, ticket_key_callback);
3023 /* despite working, appears to always return failure, so ignoring */
3025 #ifdef OPENSSL_HAVE_NUM_TICKETS
3026 # ifndef DISABLE_TLS_RESUME
3027 SSL_CTX_set_num_tickets(ctx, tls_in.host_resumable ? 1 : 0);
3029 SSL_CTX_set_num_tickets(ctx, 0); /* send no TLS1.3 stateful-tickets */
3034 /* Prepare for new connection */
3036 if (!(ssl = SSL_new(ctx)))
3037 return tls_error(US"SSL_new", NULL, NULL, errstr);
3038 state_server.lib_state.lib_ssl = ssl;
3040 /* Warning: we used to SSL_clear(ssl) here, it was removed.
3042 * With the SSL_clear(), we get strange interoperability bugs with
3043 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
3044 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
3046 * The SSL_clear() call is to let an existing SSL* be reused, typically after
3047 * session shutdown. In this case, we have a brand new object and there's no
3048 * obvious reason to immediately clear it. I'm guessing that this was
3049 * originally added because of incomplete initialisation which the clear fixed,
3050 * in some historic release.
3053 /* Set context and tell client to go ahead, except in the case of TLS startup
3054 on connection, where outputting anything now upsets the clients and tends to
3055 make them disconnect. We need to have an explicit fflush() here, to force out
3056 the response. Other smtp_printf() calls do not need it, because in non-TLS
3057 mode, the fflush() happens when smtp_getc() is called. */
3059 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
3060 if (!tls_in.on_connect)
3062 smtp_printf("220 TLS go ahead\r\n", FALSE);
3066 /* Now negotiate the TLS session. We put our own timer on it, since it seems
3067 that the OpenSSL library doesn't. */
3069 SSL_set_wfd(ssl, fileno(smtp_out));
3070 SSL_set_rfd(ssl, fileno(smtp_in));
3071 SSL_set_accept_state(ssl);
3073 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
3076 sigalrm_seen = FALSE;
3077 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3078 rc = SSL_accept(ssl);
3083 int error = SSL_get_error(ssl, rc);
3086 case SSL_ERROR_NONE:
3089 case SSL_ERROR_ZERO_RETURN:
3090 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3091 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
3093 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
3096 tls_close(NULL, TLS_NO_SHUTDOWN);
3099 /* Handle genuine errors */
3102 uschar * s = US"SSL_accept";
3103 int r = ERR_GET_REASON(ERR_peek_error());
3104 if ( r == SSL_R_WRONG_VERSION_NUMBER
3105 #ifdef SSL_R_VERSION_TOO_LOW
3106 || r == SSL_R_VERSION_TOO_LOW
3108 || r == SSL_R_UNKNOWN_PROTOCOL || r == SSL_R_UNSUPPORTED_PROTOCOL)
3109 s = string_sprintf("%s (%s)", s, SSL_get_version(ssl));
3110 (void) tls_error(s, NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
3115 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
3116 if (error == SSL_ERROR_SYSCALL)
3120 *errstr = US"SSL_accept: TCP connection closed by peer";
3123 DEBUG(D_tls) debug_printf(" - syscall %s\n", strerror(errno));
3125 (void) tls_error(US"SSL_accept", NULL,
3126 sigalrm_seen ? US"timed out"
3127 : ERR_peek_error() ? NULL : string_sprintf("ret %d", error),
3133 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
3134 ERR_clear_error(); /* Even success can leave errors in the stack. Seen with
3135 anon-authentication ciphersuite negotiated. */
3137 #ifndef DISABLE_TLS_RESUME
3138 if (SSL_session_reused(ssl))
3140 tls_in.resumption |= RESUME_USED;
3141 DEBUG(D_tls) debug_printf("Session reused\n");
3145 /* TLS has been set up. Record data for the connection,
3146 adjust the input functions to read via TLS, and initialize things. */
3148 #ifdef SSL_get_extms_support
3149 tls_in.ext_master_secret = SSL_get_extms_support(ssl) == 1;
3151 peer_cert(ssl, &tls_in, peerdn, sizeof(peerdn));
3153 tls_in.ver = tlsver_name(ssl);
3154 tls_in.cipher = construct_cipher_name(ssl, tls_in.ver, &tls_in.bits);
3155 tls_in.cipher_stdname = cipher_stdname_ssl(ssl);
3160 if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)))
3161 debug_printf("Shared ciphers: %s\n", buf);
3163 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3165 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
3166 SSL_SESSION_print_keylog(bp, SSL_get_session(ssl));
3171 #ifdef EXIM_HAVE_SESSION_TICKET
3173 SSL_SESSION * ss = SSL_get_session(ssl);
3174 if (SSL_SESSION_has_ticket(ss)) /* 1.1.0 */
3175 debug_printf("The session has a ticket, life %lu seconds\n",
3176 SSL_SESSION_get_ticket_lifetime_hint(ss));
3181 /* Record the certificate we presented */
3183 X509 * crt = SSL_get_certificate(ssl);
3184 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
3187 /* Channel-binding info for authenticators
3188 See description in https://paquier.xyz/postgresql-2/channel-binding-openssl/ */
3191 size_t len = SSL_get_peer_finished(ssl, &c, 0);
3192 int old_pool = store_pool;
3194 SSL_get_peer_finished(ssl, s = store_get((int)len, FALSE), len);
3195 store_pool = POOL_PERM;
3196 tls_in.channelbinding = b64encode_taint(CUS s, (int)len, FALSE);
3197 store_pool = old_pool;
3198 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage %p\n", tls_in.channelbinding);
3201 /* Only used by the server-side tls (tls_in), including tls_getc.
3202 Client-side (tls_out) reads (seem to?) go via
3203 smtp_read_response()/ip_recv().
3204 Hence no need to duplicate for _in and _out.
3206 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
3207 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
3208 ssl_xfer_eof = ssl_xfer_error = FALSE;
3210 receive_getc = tls_getc;
3211 receive_getbuf = tls_getbuf;
3212 receive_get_cache = tls_get_cache;
3213 receive_ungetc = tls_ungetc;
3214 receive_feof = tls_feof;
3215 receive_ferror = tls_ferror;
3216 receive_smtp_buffered = tls_smtp_buffered;
3218 tls_in.active.sock = fileno(smtp_out);
3219 tls_in.active.tls_ctx = NULL; /* not using explicit ctx for server-side */
3227 tls_client_basic_ctx_init(SSL_CTX * ctx,
3228 host_item * host, smtp_transport_options_block * ob, exim_openssl_state_st * state,
3233 /* Back-compatible old behaviour if tls_verify_certificates is set but both
3234 tls_verify_hosts and tls_try_verify_hosts are not set. Check only the specified
3235 host patterns if one of them is set with content. */
3237 if ( ( ( !ob->tls_verify_hosts || !ob->tls_verify_hosts
3238 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3240 && ( !ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts
3241 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3244 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
3246 client_verify_optional = FALSE;
3247 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
3248 client_verify_optional = TRUE;
3254 if (!expand_check(ob->tls_verify_certificates, US"tls_verify_certificates",
3257 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3259 if (state->lib_state.cabundle)
3260 { DEBUG(D_tls) debug_printf("TLS: CA bundle was preloaded\n"); }
3262 if ((rc = setup_certs(ctx, expcerts, ob->tls_crl, host, errstr)) != OK)
3265 if (expcerts && *expcerts)
3266 setup_cert_verify(ctx, client_verify_optional, verify_callback_client);
3269 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
3271 state->verify_cert_hostnames =
3273 string_domain_utf8_to_alabel(host->certname, NULL);
3277 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
3278 state->verify_cert_hostnames);
3286 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
3289 const char * hostnames[2] = { CS host->name, NULL };
3292 if (DANESSL_init(ssl, NULL, hostnames) != 1)
3293 return tls_error(US"hostnames load", host, NULL, errstr);
3295 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
3296 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
3297 ) if (rr->type == T_TLSA && rr->size > 3)
3299 const uschar * p = rr->data;
3300 uint8_t usage, selector, mtype;
3301 const char * mdname;
3305 /* Only DANE-TA(2) and DANE-EE(3) are supported */
3306 if (usage != 2 && usage != 3) continue;
3313 default: continue; /* Only match-types 0, 1, 2 are supported */
3314 case 0: mdname = NULL; break;
3315 case 1: mdname = "sha256"; break;
3316 case 2: mdname = "sha512"; break;
3320 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
3323 return tls_error(US"tlsa load", host, NULL, errstr);
3324 case 0: /* action not taken */
3328 tls_out.tlsa_usage |= 1<<usage;
3334 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
3337 #endif /*SUPPORT_DANE*/
3341 #ifndef DISABLE_TLS_RESUME
3342 /* On the client, get any stashed session for the given IP from hints db
3343 and apply it to the ssl-connection for attempted resumption. */
3346 tls_retrieve_session(tls_support * tlsp, SSL * ssl, const uschar * key)
3348 tlsp->resumption |= RESUME_SUPPORTED;
3349 if (tlsp->host_resumable)
3351 dbdata_tls_session * dt;
3353 open_db dbblock, * dbm_file;
3355 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
3356 DEBUG(D_tls) debug_printf("checking for resumable session for %s\n", key);
3357 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3359 /* key for the db is the IP */
3360 if ((dt = dbfn_read_with_length(dbm_file, key, &len)))
3362 SSL_SESSION * ss = NULL;
3363 const uschar * sess_asn1 = dt->session;
3365 len -= sizeof(dbdata_tls_session);
3366 if (!(d2i_SSL_SESSION(&ss, &sess_asn1, (long)len)))
3370 ERR_error_string_n(ERR_get_error(),
3371 ssl_errstring, sizeof(ssl_errstring));
3372 debug_printf("decoding session: %s\n", ssl_errstring);
3375 #ifdef EXIM_HAVE_SESSION_TICKET
3376 else if ( SSL_SESSION_get_ticket_lifetime_hint(ss) + dt->time_stamp
3379 DEBUG(D_tls) debug_printf("session expired\n");
3380 dbfn_delete(dbm_file, key);
3383 else if (!SSL_set_session(ssl, ss))
3387 ERR_error_string_n(ERR_get_error(),
3388 ssl_errstring, sizeof(ssl_errstring));
3389 debug_printf("applying session to ssl: %s\n", ssl_errstring);
3394 DEBUG(D_tls) debug_printf("good session\n");
3395 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
3396 tlsp->verify_override = dt->verify_override;
3397 tlsp->ocsp = dt->ocsp;
3401 DEBUG(D_tls) debug_printf("no session record\n");
3402 dbfn_close(dbm_file);
3408 /* On the client, save the session for later resumption */
3411 tls_save_session_cb(SSL * ssl, SSL_SESSION * ss)
3413 exim_openssl_state_st * cbinfo = SSL_get_ex_data(ssl, tls_exdata_idx);
3416 DEBUG(D_tls) debug_printf("tls_save_session_cb\n");
3418 if (!cbinfo || !(tlsp = cbinfo->tlsp)->host_resumable) return 0;
3420 # ifdef OPENSSL_HAVE_NUM_TICKETS
3421 if (SSL_SESSION_is_resumable(ss)) /* 1.1.1 */
3424 int len = i2d_SSL_SESSION(ss, NULL);
3425 int dlen = sizeof(dbdata_tls_session) + len;
3426 dbdata_tls_session * dt = store_get(dlen, TRUE);
3427 uschar * s = dt->session;
3428 open_db dbblock, * dbm_file;
3430 DEBUG(D_tls) debug_printf("session is resumable\n");
3431 tlsp->resumption |= RESUME_SERVER_TICKET; /* server gave us a ticket */
3433 dt->verify_override = tlsp->verify_override;
3434 dt->ocsp = tlsp->ocsp;
3435 (void) i2d_SSL_SESSION(ss, &s); /* s gets bumped to end */
3437 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3439 const uschar * key = cbinfo->host->address;
3440 dbfn_delete(dbm_file, key);
3441 dbfn_write(dbm_file, key, dt, dlen);
3442 dbfn_close(dbm_file);
3443 DEBUG(D_tls) debug_printf("wrote session (len %u) to db\n",
3452 tls_client_ctx_resume_prehandshake(
3453 exim_openssl_client_tls_ctx * exim_client_ctx, tls_support * tlsp,
3454 smtp_transport_options_block * ob, host_item * host)
3456 /* Should the client request a session resumption ticket? */
3457 if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
3459 tlsp->host_resumable = TRUE;
3461 SSL_CTX_set_session_cache_mode(exim_client_ctx->ctx,
3462 SSL_SESS_CACHE_CLIENT
3463 | SSL_SESS_CACHE_NO_INTERNAL | SSL_SESS_CACHE_NO_AUTO_CLEAR);
3464 SSL_CTX_sess_set_new_cb(exim_client_ctx->ctx, tls_save_session_cb);
3469 tls_client_ssl_resume_prehandshake(SSL * ssl, tls_support * tlsp,
3470 host_item * host, uschar ** errstr)
3472 if (tlsp->host_resumable)
3475 debug_printf("tls_resumption_hosts overrides openssl_options, enabling tickets\n");
3476 SSL_clear_options(ssl, SSL_OP_NO_TICKET);
3478 tls_exdata_idx = SSL_get_ex_new_index(0, 0, 0, 0, 0);
3479 if (!SSL_set_ex_data(ssl, tls_exdata_idx, client_static_state))
3481 tls_error(US"set ex_data", host, NULL, errstr);
3484 debug_printf("tls_exdata_idx %d cbinfo %p\n", tls_exdata_idx, client_static_state);
3487 tlsp->resumption = RESUME_SUPPORTED;
3488 /* Pick up a previous session, saved on an old ticket */
3489 tls_retrieve_session(tlsp, ssl, host->address);
3494 tls_client_resume_posthandshake(exim_openssl_client_tls_ctx * exim_client_ctx,
3497 if (SSL_session_reused(exim_client_ctx->ssl))
3499 DEBUG(D_tls) debug_printf("The session was reused\n");
3500 tlsp->resumption |= RESUME_USED;
3503 #endif /* !DISABLE_TLS_RESUME */
3506 /*************************************************
3507 * Start a TLS session in a client *
3508 *************************************************/
3510 /* Called from the smtp transport after STARTTLS has been accepted.
3513 cctx connection context
3514 conn_args connection details
3515 cookie datum for randomness; can be NULL
3516 tlsp record details of TLS channel configuration here; must be non-NULL
3517 errstr error string pointer
3519 Returns: TRUE for success with TLS session context set in connection context,
3524 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
3525 void * cookie, tls_support * tlsp, uschar ** errstr)
3527 host_item * host = conn_args->host; /* for msgs and option-tests */
3528 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
3529 smtp_transport_options_block * ob = tb
3530 ? (smtp_transport_options_block *)tb->options_block
3531 : &smtp_transport_option_defaults;
3532 exim_openssl_client_tls_ctx * exim_client_ctx;
3533 uschar * expciphers;
3535 static uschar peerdn[256];
3537 #ifndef DISABLE_OCSP
3538 BOOL request_ocsp = FALSE;
3539 BOOL require_ocsp = FALSE;
3543 store_pool = POOL_PERM;
3544 exim_client_ctx = store_get(sizeof(exim_openssl_client_tls_ctx), FALSE);
3545 exim_client_ctx->corked = NULL;
3549 tlsp->tlsa_usage = 0;
3552 #ifndef DISABLE_OCSP
3554 # ifdef SUPPORT_DANE
3555 /*XXX this should be moved to caller, to be common across gnutls/openssl */
3556 if ( conn_args->dane
3557 && ob->hosts_request_ocsp[0] == '*'
3558 && ob->hosts_request_ocsp[1] == '\0'
3561 /* Unchanged from default. Use a safer one under DANE */
3562 request_ocsp = TRUE;
3563 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
3564 " {= {4}{$tls_out_tlsa_usage}} } "
3570 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK))
3571 request_ocsp = TRUE;
3573 # ifdef SUPPORT_DANE
3577 verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3581 rc = tls_init(host, ob,
3582 #ifndef DISABLE_OCSP
3583 (void *)(long)request_ocsp,
3585 cookie, &client_static_state, tlsp, errstr);
3586 if (rc != OK) return FALSE;
3588 exim_client_ctx->ctx = client_static_state->lib_state.lib_ctx;
3590 tlsp->certificate_verified = FALSE;
3591 client_verify_callback_called = FALSE;
3595 if (conn_args->dane)
3597 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
3598 other failures should be treated as problems. */
3599 if (ob->dane_require_tls_ciphers &&
3600 !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
3601 &expciphers, errstr))
3603 if (expciphers && *expciphers == '\0')
3608 !expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
3609 &expciphers, errstr))
3612 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
3613 are separated by underscores. So that I can use either form in my tests, and
3614 also for general convenience, we turn underscores into hyphens here. */
3618 uschar *s = expciphers;
3619 while (*s) { if (*s == '_') *s = '-'; s++; }
3620 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
3621 if (!SSL_CTX_set_cipher_list(exim_client_ctx->ctx, CS expciphers))
3623 tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
3629 if (conn_args->dane)
3631 SSL_CTX_set_verify(exim_client_ctx->ctx,
3632 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
3633 verify_callback_client_dane);
3635 if (!DANESSL_library_init())
3637 tls_error(US"library init", host, NULL, errstr);
3640 if (DANESSL_CTX_init(exim_client_ctx->ctx) <= 0)
3642 tls_error(US"context init", host, NULL, errstr);
3650 if (tls_client_basic_ctx_init(exim_client_ctx->ctx, host, ob,
3651 client_static_state, errstr) != OK)
3654 #ifndef DISABLE_TLS_RESUME
3655 tls_client_ctx_resume_prehandshake(exim_client_ctx, tlsp, ob, host);
3659 if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx)))
3661 tls_error(US"SSL_new", host, NULL, errstr);
3664 SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx));
3666 SSL_set_fd(exim_client_ctx->ssl, cctx->sock);
3667 SSL_set_connect_state(exim_client_ctx->ssl);
3671 if (!expand_check(ob->tls_sni, US"tls_sni", &tlsp->sni, errstr))
3675 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
3677 else if (!Ustrlen(tlsp->sni))
3681 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
3682 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tlsp->sni);
3683 SSL_set_tlsext_host_name(exim_client_ctx->ssl, tlsp->sni);
3685 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
3692 if (conn_args->dane)
3693 if (dane_tlsa_load(exim_client_ctx->ssl, host, &conn_args->tlsa_dnsa, errstr) != OK)
3697 #ifndef DISABLE_OCSP
3698 /* Request certificate status at connection-time. If the server
3699 does OCSP stapling we will get the callback (set in tls_init()) */
3700 # ifdef SUPPORT_DANE
3704 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
3705 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
3707 { /* Re-eval now $tls_out_tlsa_usage is populated. If
3708 this means we avoid the OCSP request, we wasted the setup
3709 cost in tls_init(). */
3710 require_ocsp = verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
3711 request_ocsp = require_ocsp
3712 || verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3719 SSL_set_tlsext_status_type(exim_client_ctx->ssl, TLSEXT_STATUSTYPE_ocsp);
3720 client_static_state->u_ocsp.client.verify_required = require_ocsp;
3721 tlsp->ocsp = OCSP_NOT_RESP;
3725 #ifndef DISABLE_TLS_RESUME
3726 if (!tls_client_ssl_resume_prehandshake(exim_client_ctx->ssl, tlsp, host,
3731 #ifndef DISABLE_EVENT
3732 client_static_state->event_action = tb ? tb->event_action : NULL;
3735 /* There doesn't seem to be a built-in timeout on connection. */
3737 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
3738 sigalrm_seen = FALSE;
3739 ALARM(ob->command_timeout);
3740 rc = SSL_connect(exim_client_ctx->ssl);
3744 if (conn_args->dane)
3745 DANESSL_cleanup(exim_client_ctx->ssl);
3750 tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, errstr);
3756 debug_printf("SSL_connect succeeded\n");
3757 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3759 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
3760 SSL_SESSION_print_keylog(bp, SSL_get_session(exim_client_ctx->ssl));
3766 #ifndef DISABLE_TLS_RESUME
3767 tls_client_resume_posthandshake(exim_client_ctx, tlsp);
3770 #ifdef SSL_get_extms_support
3771 tlsp->ext_master_secret = SSL_get_extms_support(exim_client_ctx->ssl) == 1;
3773 peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn));
3775 tlsp->ver = tlsver_name(exim_client_ctx->ssl);
3776 tlsp->cipher = construct_cipher_name(exim_client_ctx->ssl, tlsp->ver, &tlsp->bits);
3777 tlsp->cipher_stdname = cipher_stdname_ssl(exim_client_ctx->ssl);
3779 /* Record the certificate we presented */
3781 X509 * crt = SSL_get_certificate(exim_client_ctx->ssl);
3782 tlsp->ourcert = crt ? X509_dup(crt) : NULL;
3785 /*XXX will this work with continued-TLS? */
3786 /* Channel-binding info for authenticators */
3789 size_t len = SSL_get_finished(exim_client_ctx->ssl, &c, 0);
3790 int old_pool = store_pool;
3792 SSL_get_finished(exim_client_ctx->ssl, s = store_get((int)len, TRUE), len);
3793 store_pool = POOL_PERM;
3794 tlsp->channelbinding = b64encode_taint(CUS s, (int)len, TRUE);
3795 store_pool = old_pool;
3796 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage %p %p\n", tlsp->channelbinding, tlsp);
3799 tlsp->active.sock = cctx->sock;
3800 tlsp->active.tls_ctx = exim_client_ctx;
3801 cctx->tls_ctx = exim_client_ctx;
3810 tls_refill(unsigned lim)
3812 SSL * ssl = state_server.lib_state.lib_ssl;
3816 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
3817 ssl_xfer_buffer, ssl_xfer_buffer_size);
3820 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3821 inbytes = SSL_read(ssl, CS ssl_xfer_buffer,
3822 MIN(ssl_xfer_buffer_size, lim));
3823 error = SSL_get_error(ssl, inbytes);
3824 if (smtp_receive_timeout > 0) ALARM_CLR(0);
3826 if (had_command_timeout) /* set by signal handler */
3827 smtp_command_timeout_exit(); /* does not return */
3828 if (had_command_sigterm)
3829 smtp_command_sigterm_exit();
3830 if (had_data_timeout)
3831 smtp_data_timeout_exit();
3832 if (had_data_sigint)
3833 smtp_data_sigint_exit();
3835 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
3836 closed down, not that the socket itself has been closed down. Revert to
3837 non-SSL handling. */
3841 case SSL_ERROR_NONE:
3844 case SSL_ERROR_ZERO_RETURN:
3845 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3847 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
3850 tls_close(NULL, TLS_NO_SHUTDOWN);
3853 /* Handle genuine errors */
3855 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3856 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
3857 ssl_xfer_error = TRUE;
3861 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
3862 DEBUG(D_tls) if (error == SSL_ERROR_SYSCALL)
3863 debug_printf(" - syscall %s\n", strerror(errno));
3864 ssl_xfer_error = TRUE;
3868 #ifndef DISABLE_DKIM
3869 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
3871 ssl_xfer_buffer_hwm = inbytes;
3872 ssl_xfer_buffer_lwm = 0;
3877 /*************************************************
3878 * TLS version of getc *
3879 *************************************************/
3881 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
3882 it refills the buffer via the SSL reading function.
3884 Arguments: lim Maximum amount to read/buffer
3885 Returns: the next character or EOF
3887 Only used by the server-side TLS.
3891 tls_getc(unsigned lim)
3893 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
3894 if (!tls_refill(lim))
3895 return ssl_xfer_error ? EOF : smtp_getc(lim);
3897 /* Something in the buffer; return next uschar */
3899 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
3903 tls_getbuf(unsigned * len)
3908 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
3909 if (!tls_refill(*len))
3911 if (!ssl_xfer_error) return smtp_getbuf(len);
3916 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
3918 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
3919 ssl_xfer_buffer_lwm += size;
3928 #ifndef DISABLE_DKIM
3929 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
3931 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
3937 tls_could_read(void)
3939 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm
3940 || SSL_pending(state_server.lib_state.lib_ssl) > 0;
3944 /*************************************************
3945 * Read bytes from TLS channel *
3946 *************************************************/
3950 ct_ctx client context pointer, or NULL for the one global server context
3954 Returns: the number of bytes read
3955 -1 after a failed read, including EOF
3957 Only used by the client-side TLS.
3961 tls_read(void * ct_ctx, uschar *buff, size_t len)
3963 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
3964 : state_server.lib_state.lib_ssl;
3968 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
3969 buff, (unsigned int)len);
3972 inbytes = SSL_read(ssl, CS buff, len);
3973 error = SSL_get_error(ssl, inbytes);
3975 if (error == SSL_ERROR_ZERO_RETURN)
3977 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3980 else if (error != SSL_ERROR_NONE)
3990 /*************************************************
3991 * Write bytes down TLS channel *
3992 *************************************************/
3996 ct_ctx client context pointer, or NULL for the one global server context
3999 more further data expected soon
4001 Returns: the number of bytes after a successful write,
4002 -1 after a failed write
4004 Used by both server-side and client-side TLS. Calling with len zero and more unset
4005 will flush buffered writes; buff can be null for this case.
4009 tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
4012 int outbytes, error;
4014 ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
4015 : state_server.lib_state.lib_ssl;
4016 static gstring * server_corked = NULL;
4017 gstring ** corkedp = ct_ctx
4018 ? &((exim_openssl_client_tls_ctx *)ct_ctx)->corked : &server_corked;
4019 gstring * corked = *corkedp;
4021 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
4022 buff, (unsigned long)len, more ? ", more" : "");
4024 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
4025 "more" is notified. This hack is only ok if small amounts are involved AND only
4026 one stream does it, in one context (i.e. no store reset). Currently it is used
4027 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only.
4028 We support callouts done by the server process by using a separate client
4029 context for the stashed information. */
4030 /* + if PIPE_COMMAND, banner & ehlo-resp for smmtp-on-connect. Suspect there's
4031 a store reset there, so use POOL_PERM. */
4032 /* + if CHUNKING, cmds EHLO,MAIL,RCPT(s),BDAT */
4036 if (!len) buff = US &error; /* dummy just so that string_catn is ok */
4038 #ifndef DISABLE_PIPE_CONNECT
4039 int save_pool = store_pool;
4040 store_pool = POOL_PERM;
4043 corked = string_catn(corked, buff, len);
4045 #ifndef DISABLE_PIPE_CONNECT
4046 store_pool = save_pool;
4054 buff = CUS corked->s;
4059 for (int left = len; left > 0;)
4061 DEBUG(D_tls) debug_printf("SSL_write(%p, %p, %d)\n", ssl, buff, left);
4063 outbytes = SSL_write(ssl, CS buff, left);
4064 error = SSL_get_error(ssl, outbytes);
4065 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
4068 case SSL_ERROR_NONE: /* the usual case */
4074 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4075 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
4078 case SSL_ERROR_ZERO_RETURN:
4079 log_write(0, LOG_MAIN, "SSL channel closed on write");
4082 case SSL_ERROR_SYSCALL:
4083 if (ct_ctx || errno != ECONNRESET || !f.smtp_in_quit)
4084 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
4085 sender_fullhost ? sender_fullhost : US"<unknown>",
4087 else if (LOGGING(protocol_detail))
4088 log_write(0, LOG_MAIN, "[%s] after QUIT, client reset TCP before"
4089 " SMTP response and TLS close\n", sender_host_address);
4091 DEBUG(D_tls) debug_printf("[%s] SSL_write: after QUIT,"
4092 " client reset TCP before TLS close\n", sender_host_address);
4096 log_write(0, LOG_MAIN, "SSL_write error %d", error);
4105 /*************************************************
4106 * Close down a TLS session *
4107 *************************************************/
4109 /* This is also called from within a delivery subprocess forked from the
4110 daemon, to shut down the TLS library, without actually doing a shutdown (which
4111 would tamper with the SSL session in the parent process).
4114 ct_ctx client TLS context pointer, or NULL for the one global server context
4115 shutdown 1 if TLS close-alert is to be sent,
4116 2 if also response to be waited for
4120 Used by both server-side and client-side TLS.
4124 tls_close(void * ct_ctx, int shutdown)
4126 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4127 SSL **sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4128 int *fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4130 if (*fdp < 0) return; /* TLS was not active */
4135 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
4136 shutdown > 1 ? " (with response-wait)" : "");
4138 if ( (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
4142 rc = SSL_shutdown(*sslp); /* wait for response */
4146 if (rc < 0) DEBUG(D_tls)
4148 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4149 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4153 if (!o_ctx) /* server side */
4155 #ifndef DISABLE_OCSP
4156 sk_X509_pop_free(state_server.verify_stack, X509_free);
4157 state_server.verify_stack = NULL;
4160 receive_getc = smtp_getc;
4161 receive_getbuf = smtp_getbuf;
4162 receive_get_cache = smtp_get_cache;
4163 receive_ungetc = smtp_ungetc;
4164 receive_feof = smtp_feof;
4165 receive_ferror = smtp_ferror;
4166 receive_smtp_buffered = smtp_buffered;
4167 tls_in.active.tls_ctx = NULL;
4169 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
4180 /*************************************************
4181 * Let tls_require_ciphers be checked at startup *
4182 *************************************************/
4184 /* The tls_require_ciphers option, if set, must be something which the
4187 Returns: NULL on success, or error message
4191 tls_validate_require_cipher(void)
4194 uschar *s, *expciphers, *err;
4198 if (!(tls_require_ciphers && *tls_require_ciphers))
4201 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
4203 return US"failed to expand tls_require_ciphers";
4205 if (!(expciphers && *expciphers))
4208 /* normalisation ripped from above */
4210 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
4214 if (lib_ctx_new(&ctx, NULL, &err) == OK)
4217 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
4219 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
4221 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4222 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
4223 expciphers, ssl_errstring);
4234 /*************************************************
4235 * Report the library versions. *
4236 *************************************************/
4238 /* There have historically been some issues with binary compatibility in
4239 OpenSSL libraries; if Exim (like many other applications) is built against
4240 one version of OpenSSL but the run-time linker picks up another version,
4241 it can result in serious failures, including crashing with a SIGSEGV. So
4242 report the version found by the compiler and the run-time version.
4244 Note: some OS vendors backport security fixes without changing the version
4245 number/string, and the version date remains unchanged. The _build_ date
4246 will change, so we can more usefully assist with version diagnosis by also
4247 reporting the build date.
4249 Arguments: a FILE* to print the results to
4254 tls_version_report(FILE *f)
4256 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
4259 OPENSSL_VERSION_TEXT,
4260 SSLeay_version(SSLEAY_VERSION),
4261 SSLeay_version(SSLEAY_BUILT_ON));
4262 /* third line is 38 characters for the %s and the line is 73 chars long;
4263 the OpenSSL output includes a "built on: " prefix already. */
4269 /*************************************************
4270 * Random number generation *
4271 *************************************************/
4273 /* Pseudo-random number generation. The result is not expected to be
4274 cryptographically strong but not so weak that someone will shoot themselves
4275 in the foot using it as a nonce in input in some email header scheme or
4276 whatever weirdness they'll twist this into. The result should handle fork()
4277 and avoid repeating sequences. OpenSSL handles that for us.
4281 Returns a random number in range [0, max-1]
4285 vaguely_random_number(int max)
4289 static pid_t pidlast = 0;
4291 uschar smallbuf[sizeof(r)];
4297 if (pidnow != pidlast)
4299 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
4300 is unique for each thread", this doesn't apparently apply across processes,
4301 so our own warning from vaguely_random_number_fallback() applies here too.
4302 Fix per PostgreSQL. */
4308 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
4312 gettimeofday(&r.tv, NULL);
4315 RAND_seed(US (&r), sizeof(r));
4317 /* We're after pseudo-random, not random; if we still don't have enough data
4318 in the internal PRNG then our options are limited. We could sleep and hope
4319 for entropy to come along (prayer technique) but if the system is so depleted
4320 in the first place then something is likely to just keep taking it. Instead,
4321 we'll just take whatever little bit of pseudo-random we can still manage to
4324 needed_len = sizeof(r);
4325 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
4326 asked for a number less than 10. */
4327 for (r = max, i = 0; r; ++i)
4333 #ifdef EXIM_HAVE_RAND_PSEUDO
4334 /* We do not care if crypto-strong */
4335 i = RAND_pseudo_bytes(smallbuf, needed_len);
4337 i = RAND_bytes(smallbuf, needed_len);
4343 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
4344 return vaguely_random_number_fallback(max);
4348 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
4351 /* We don't particularly care about weighted results; if someone wants
4352 smooth distribution and cares enough then they should submit a patch then. */
4359 /*************************************************
4360 * OpenSSL option parse *
4361 *************************************************/
4363 /* Parse one option for tls_openssl_options_parse below
4366 name one option name
4367 value place to store a value for it
4368 Returns success or failure in parsing
4374 tls_openssl_one_option_parse(uschar *name, long *value)
4377 int last = exim_openssl_options_size;
4378 while (last > first)
4380 int middle = (first + last)/2;
4381 int c = Ustrcmp(name, exim_openssl_options[middle].name);
4384 *value = exim_openssl_options[middle].value;
4398 /*************************************************
4399 * OpenSSL option parsing logic *
4400 *************************************************/
4402 /* OpenSSL has a number of compatibility options which an administrator might
4403 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
4404 we look like log_selector.
4407 option_spec the administrator-supplied string of options
4408 results ptr to long storage for the options bitmap
4409 Returns success or failure
4413 tls_openssl_options_parse(uschar *option_spec, long *results)
4416 uschar * exp, * end;
4418 BOOL adding, item_parsed;
4420 /* Server: send no (<= TLS1.2) session tickets */
4421 result = SSL_OP_NO_TICKET;
4423 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
4424 from default because it increases BEAST susceptibility. */
4425 #ifdef SSL_OP_NO_SSLv2
4426 result |= SSL_OP_NO_SSLv2;
4428 #ifdef SSL_OP_NO_SSLv3
4429 result |= SSL_OP_NO_SSLv3;
4431 #ifdef SSL_OP_SINGLE_DH_USE
4432 result |= SSL_OP_SINGLE_DH_USE;
4434 #ifdef SSL_OP_NO_RENEGOTIATION
4435 result |= SSL_OP_NO_RENEGOTIATION;
4444 if (!expand_check(option_spec, US"openssl_options", &exp, &end))
4447 for (uschar * s = exp; *s; /**/)
4449 while (isspace(*s)) ++s;
4452 if (*s != '+' && *s != '-')
4454 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
4455 "+ or - expected but found \"%s\"\n", s);
4458 adding = *s++ == '+';
4459 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
4462 item_parsed = tls_openssl_one_option_parse(s, &item);
4466 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
4469 DEBUG(D_tls) debug_printf("openssl option, %s %08lx: %08lx (%s)\n",
4470 adding ? "adding to " : "removing from", result, item, s);
4482 #endif /*!MACRO_PREDEF*/
4485 /* End of tls-openssl.c */