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 */
797 /*XXX we could arrange to call this during prelo for a null tls_certificate option.
798 The normal cache inval + relo will suffice.
799 Just need a timer for inval. */
802 tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr)
810 DEBUG(D_tls) debug_printf("TLS: generating selfsigned server cert\n");
811 where = US"allocating pkey";
812 if (!(pkey = EVP_PKEY_new()))
815 where = US"allocating cert";
816 if (!(x509 = X509_new()))
819 where = US"generating pkey";
820 if (!(rsa = rsa_callback(NULL, 0, 2048)))
823 where = US"assigning pkey";
824 if (!EVP_PKEY_assign_RSA(pkey, rsa))
827 X509_set_version(x509, 2); /* N+1 - version 3 */
828 ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
829 X509_gmtime_adj(X509_get_notBefore(x509), 0);
830 X509_gmtime_adj(X509_get_notAfter(x509), (long)2 * 60 * 60); /* 2 hour */
831 X509_set_pubkey(x509, pkey);
833 name = X509_get_subject_name(x509);
834 X509_NAME_add_entry_by_txt(name, "C",
835 MBSTRING_ASC, CUS "UK", -1, -1, 0);
836 X509_NAME_add_entry_by_txt(name, "O",
837 MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0);
838 X509_NAME_add_entry_by_txt(name, "CN",
839 MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0);
840 X509_set_issuer_name(x509, name);
842 where = US"signing cert";
843 if (!X509_sign(x509, pkey, EVP_md5()))
846 where = US"installing selfsign cert";
847 if (!SSL_CTX_use_certificate(sctx, x509))
850 where = US"installing selfsign key";
851 if (!SSL_CTX_use_PrivateKey(sctx, pkey))
857 (void) tls_error(where, NULL, NULL, errstr);
858 if (x509) X509_free(x509);
859 if (pkey) EVP_PKEY_free(pkey);
869 /*************************************************
870 * Information callback *
871 *************************************************/
873 /* The SSL library functions call this from time to time to indicate what they
874 are doing. We copy the string to the debugging output when TLS debugging has
886 info_callback(SSL *s, int where, int ret)
892 if (where & SSL_ST_CONNECT)
893 str = US"SSL_connect";
894 else if (where & SSL_ST_ACCEPT)
895 str = US"SSL_accept";
897 str = US"SSL info (undefined)";
899 if (where & SSL_CB_LOOP)
900 debug_printf("%s: %s\n", str, SSL_state_string_long(s));
901 else if (where & SSL_CB_ALERT)
902 debug_printf("SSL3 alert %s:%s:%s\n",
903 str = where & SSL_CB_READ ? US"read" : US"write",
904 SSL_alert_type_string_long(ret), SSL_alert_desc_string_long(ret));
905 else if (where & SSL_CB_EXIT)
908 debug_printf("%s: failed in %s\n", str, SSL_state_string_long(s));
910 debug_printf("%s: error in %s\n", str, SSL_state_string_long(s));
912 else if (where & SSL_CB_HANDSHAKE_START)
913 debug_printf("%s: hshake start: %s\n", str, SSL_state_string_long(s));
914 else if (where & SSL_CB_HANDSHAKE_DONE)
915 debug_printf("%s: hshake done: %s\n", str, SSL_state_string_long(s));
919 #ifdef OPENSSL_HAVE_KEYLOG_CB
921 keylog_callback(const SSL *ssl, const char *line)
925 DEBUG(D_tls) debug_printf("%.200s\n", line);
926 if (!(filename = getenv("SSLKEYLOGFILE"))) return;
927 if (!(fp = fopen(filename, "a"))) return;
928 fprintf(fp, "%s\n", line);
937 #ifndef DISABLE_EVENT
939 verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
940 BOOL *calledp, const BOOL *optionalp, const uschar * what)
946 ev = tlsp == &tls_out ? client_static_state->event_action : event_action;
949 DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth);
950 old_cert = tlsp->peercert;
951 tlsp->peercert = X509_dup(cert);
952 /* NB we do not bother setting peerdn */
953 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
955 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
956 "depth=%d cert=%s: %s",
957 tlsp == &tls_out ? deliver_host_address : sender_host_address,
958 what, depth, dn, yield);
962 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
963 return 1; /* reject (leaving peercert set) */
965 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
966 "(host in tls_try_verify_hosts)\n");
967 tlsp->verify_override = TRUE;
969 X509_free(tlsp->peercert);
970 tlsp->peercert = old_cert;
976 /*************************************************
977 * Callback for verification *
978 *************************************************/
980 /* The SSL library does certificate verification if set up to do so. This
981 callback has the current yes/no state is in "state". If verification succeeded,
982 we set the certificate-verified flag. If verification failed, what happens
983 depends on whether the client is required to present a verifiable certificate
986 If verification is optional, we change the state to yes, but still log the
987 verification error. For some reason (it really would help to have proper
988 documentation of OpenSSL), this callback function then gets called again, this
989 time with state = 1. We must take care not to set the private verified flag on
990 the second time through.
992 Note: this function is not called if the client fails to present a certificate
993 when asked. We get here only if a certificate has been received. Handling of
994 optional verification for this case is done when requesting SSL to verify, by
995 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
997 May be called multiple times for different issues with a certificate, even
998 for a given "depth" in the certificate chain.
1001 preverify_ok current yes/no state as 1/0
1002 x509ctx certificate information.
1003 tlsp per-direction (client vs. server) support data
1004 calledp has-been-called flag
1005 optionalp verification-is-optional flag
1007 Returns: 0 if verification should fail, otherwise 1
1011 verify_callback(int preverify_ok, X509_STORE_CTX * x509ctx,
1012 tls_support * tlsp, BOOL * calledp, BOOL * optionalp)
1014 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
1015 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
1018 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
1020 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
1021 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1022 tlsp == &tls_out ? deliver_host_address : sender_host_address);
1025 dn[sizeof(dn)-1] = '\0';
1027 tlsp->verify_override = FALSE;
1028 if (preverify_ok == 0)
1030 uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])",
1031 *verify_mode, sender_host_address)
1033 log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
1034 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1036 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn);
1040 if (!tlsp->peercert)
1041 tlsp->peercert = X509_dup(cert); /* record failing cert */
1042 return 0; /* reject */
1044 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
1045 "tls_try_verify_hosts)\n");
1046 tlsp->verify_override = TRUE;
1049 else if (depth != 0)
1051 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
1052 #ifndef DISABLE_OCSP
1053 if (tlsp == &tls_out && client_static_state->u_ocsp.client.verify_store)
1054 { /* client, wanting stapling */
1055 /* Add the server cert's signing chain as the one
1056 for the verification of the OCSP stapled information. */
1058 if (!X509_STORE_add_cert(client_static_state->u_ocsp.client.verify_store,
1061 sk_X509_push(client_static_state->verify_stack, cert);
1064 #ifndef DISABLE_EVENT
1065 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
1066 return 0; /* reject, with peercert set */
1071 const uschar * verify_cert_hostnames;
1073 if ( tlsp == &tls_out
1074 && ((verify_cert_hostnames = client_static_state->verify_cert_hostnames)))
1075 /* client, wanting hostname check */
1078 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
1079 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
1080 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
1082 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
1083 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
1086 const uschar * list = verify_cert_hostnames;
1089 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
1090 if ((rc = X509_check_host(cert, CCS name, 0,
1091 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
1092 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
1097 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1098 tlsp == &tls_out ? deliver_host_address : sender_host_address);
1105 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
1108 uschar * extra = verify_mode
1109 ? string_sprintf(" (during %c-verify for [%s])",
1110 *verify_mode, sender_host_address)
1112 log_write(0, LOG_MAIN,
1113 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
1114 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1115 extra, dn, verify_cert_hostnames);
1119 if (!tlsp->peercert)
1120 tlsp->peercert = X509_dup(cert); /* record failing cert */
1121 return 0; /* reject */
1123 DEBUG(D_tls) debug_printf("SSL verify name failure overridden (host in "
1124 "tls_try_verify_hosts)\n");
1125 tlsp->verify_override = TRUE;
1129 #ifndef DISABLE_EVENT
1130 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
1131 return 0; /* reject, with peercert set */
1134 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
1135 *calledp ? "" : " authenticated", dn);
1139 return 1; /* accept, at least for this level */
1143 verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
1145 return verify_callback(preverify_ok, x509ctx, &tls_out,
1146 &client_verify_callback_called, &client_verify_optional);
1150 verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
1152 return verify_callback(preverify_ok, x509ctx, &tls_in,
1153 &server_verify_callback_called, &server_verify_optional);
1159 /* This gets called *by* the dane library verify callback, which interposes
1163 verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
1165 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
1167 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
1168 #ifndef DISABLE_EVENT
1169 BOOL dummy_called, optional = FALSE;
1172 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
1174 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
1175 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1176 deliver_host_address);
1179 dn[sizeof(dn)-1] = '\0';
1181 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
1182 preverify_ok ? "ok":"BAD", depth, dn);
1184 #ifndef DISABLE_EVENT
1185 if (verify_event(&tls_out, cert, depth, dn,
1186 &dummy_called, &optional, US"DANE"))
1187 return 0; /* reject, with peercert set */
1190 if (preverify_ok == 1)
1192 tls_out.dane_verified = TRUE;
1193 #ifndef DISABLE_OCSP
1194 if (client_static_state->u_ocsp.client.verify_store)
1195 { /* client, wanting stapling */
1196 /* Add the server cert's signing chain as the one
1197 for the verification of the OCSP stapled information. */
1199 if (!X509_STORE_add_cert(client_static_state->u_ocsp.client.verify_store,
1202 sk_X509_push(client_static_state->verify_stack, cert);
1208 int err = X509_STORE_CTX_get_error(x509ctx);
1210 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
1211 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
1214 return preverify_ok;
1217 #endif /*SUPPORT_DANE*/
1220 #ifndef DISABLE_OCSP
1221 /*************************************************
1222 * Load OCSP information into state *
1223 *************************************************/
1224 /* Called to load the server OCSP response from the given file into memory, once
1225 caller has determined this is needed. Checks validity. Debugs a message
1228 ASSUMES: single response, for single cert.
1231 state various parts of session state
1232 filename the filename putatively holding an OCSP response
1233 is_pem file is PEM format; otherwise is DER
1237 ocsp_load_response(exim_openssl_state_st * state, const uschar * filename,
1241 OCSP_RESPONSE * resp;
1242 OCSP_BASICRESP * basic_response;
1243 OCSP_SINGLERESP * single_response;
1244 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
1245 STACK_OF(X509) * sk;
1246 unsigned long verify_flags;
1247 int status, reason, i;
1250 debug_printf("tls_ocsp_file (%s) '%s'\n", is_pem ? "PEM" : "DER", filename);
1252 if (!filename || !*filename) return;
1255 if (!(bio = BIO_new_file(CS filename, "rb")))
1257 log_write(0, LOG_MAIN|LOG_PANIC,
1258 "Failed to open OCSP response file \"%s\": %.100s",
1259 filename, ERR_reason_error_string(ERR_get_error()));
1265 uschar * data, * freep;
1268 if (!PEM_read_bio(bio, &dummy, &dummy, &data, &len))
1270 log_write(0, LOG_MAIN|LOG_PANIC, "Failed to read PEM file \"%s\": %.100s",
1271 filename, ERR_reason_error_string(ERR_get_error()));
1275 resp = d2i_OCSP_RESPONSE(NULL, CUSS &data, len);
1276 OPENSSL_free(freep);
1279 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
1284 log_write(0, LOG_MAIN|LOG_PANIC, "Error reading OCSP response from \"%s\": %s",
1285 filename, ERR_reason_error_string(ERR_get_error()));
1289 if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
1291 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
1292 OCSP_response_status_str(status), status);
1298 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1299 OCSP_RESPONSE_print(bp, resp, 0); /* extreme debug: stapling content */
1304 if (!(basic_response = OCSP_response_get1_basic(resp)))
1307 debug_printf("OCSP response parse error: unable to extract basic response.\n");
1311 sk = state->verify_stack;
1312 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
1314 /* May need to expose ability to adjust those flags?
1315 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
1316 OCSP_TRUSTOTHER OCSP_NOINTERN */
1318 /* This does a full verify on the OCSP proof before we load it for serving
1319 up; possibly overkill - just date-checks might be nice enough.
1321 OCSP_basic_verify takes a "store" arg, but does not
1322 use it for the chain verification, which is all we do
1323 when OCSP_NOVERIFY is set. The content from the wire
1324 "basic_response" and a cert-stack "sk" are all that is used.
1326 We have a stack, loaded in setup_certs() if tls_verify_certificates
1327 was a file (not a directory, or "system"). It is unfortunate we
1328 cannot used the connection context store, as that would neatly
1329 handle the "system" case too, but there seems to be no library
1330 function for getting a stack from a store.
1331 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
1332 We do not free the stack since it could be needed a second time for
1335 Separately we might try to replace using OCSP_basic_verify() - which seems to not
1336 be a public interface into the OpenSSL library (there's no manual entry) -
1337 But what with? We also use OCSP_basic_verify in the client stapling callback.
1338 And there we NEED it; we must verify that status... unless the
1339 library does it for us anyway? */
1341 if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0)
1345 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1346 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
1351 /* Here's the simplifying assumption: there's only one response, for the
1352 one certificate we use, and nothing for anything else in a chain. If this
1353 proves false, we need to extract a cert id from our issued cert
1354 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
1355 right cert in the stack and then calls OCSP_single_get0_status()).
1357 I'm hoping to avoid reworking a bunch more of how we handle state here.
1359 XXX that will change when we add support for (TLS1.3) whole-chain stapling
1362 if (!(single_response = OCSP_resp_get0(basic_response, 0)))
1365 debug_printf("Unable to get first response from OCSP basic response.\n");
1369 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
1370 if (status != V_OCSP_CERTSTATUS_GOOD)
1372 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
1373 OCSP_cert_status_str(status), status,
1374 OCSP_crl_reason_str(reason), reason);
1378 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1380 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
1385 /* Add the resp to the list used by tls_server_stapling_cb() */
1387 ocsp_resplist ** op = &state->u_ocsp.server.olist, * oentry;
1388 while (oentry = *op)
1390 *op = oentry = store_get(sizeof(ocsp_resplist), FALSE);
1391 oentry->next = NULL;
1392 oentry->resp = resp;
1397 if (f.running_in_test_harness)
1399 extern char ** environ;
1400 if (environ) for (uschar ** p = USS environ; *p; p++)
1401 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1403 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
1404 goto supply_response;
1412 ocsp_free_response_list(exim_openssl_state_st * cbinfo)
1414 for (ocsp_resplist * olist = cbinfo->u_ocsp.server.olist; olist;
1415 olist = olist->next)
1416 OCSP_RESPONSE_free(olist->resp);
1417 cbinfo->u_ocsp.server.olist = NULL;
1419 #endif /*!DISABLE_OCSP*/
1426 tls_add_certfile(SSL_CTX * sctx, exim_openssl_state_st * cbinfo, uschar * file,
1429 DEBUG(D_tls) debug_printf("tls_certificate file '%s'\n", file);
1430 if (!SSL_CTX_use_certificate_chain_file(sctx, CS file))
1431 return tls_error(string_sprintf(
1432 "SSL_CTX_use_certificate_chain_file file=%s", file),
1433 cbinfo->host, NULL, errstr);
1438 tls_add_pkeyfile(SSL_CTX * sctx, exim_openssl_state_st * cbinfo, uschar * file,
1441 DEBUG(D_tls) debug_printf("tls_privatekey file '%s'\n", file);
1442 if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM))
1443 return tls_error(string_sprintf(
1444 "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr);
1451 /* Called once during tls_init and possibly again during TLS setup, for a
1452 new context, if Server Name Indication was used and tls_sni was seen in
1453 the certificate string.
1456 sctx the SSL_CTX* to update
1457 state various parts of session state
1458 errstr error string pointer
1460 Returns: OK/DEFER/FAIL
1464 tls_expand_session_files(SSL_CTX * sctx, exim_openssl_state_st * state,
1469 if (!state->certificate)
1471 if (!state->is_server) /* client */
1474 if (tls_install_selfsign(sctx, errstr) != OK)
1481 if ( !reexpand_tls_files_for_sni
1482 && ( Ustrstr(state->certificate, US"tls_sni")
1483 || Ustrstr(state->certificate, US"tls_in_sni")
1484 || Ustrstr(state->certificate, US"tls_out_sni")
1486 reexpand_tls_files_for_sni = TRUE;
1488 if (!expand_check(state->certificate, US"tls_certificate", &expanded, errstr))
1492 if (state->is_server)
1494 const uschar * file_list = expanded;
1497 #ifndef DISABLE_OCSP
1498 const uschar * olist = state->u_ocsp.server.file;
1501 BOOL fmt_pem = FALSE;
1504 if (!expand_check(olist, US"tls_ocsp_file", USS &olist, errstr))
1506 if (olist && !*olist)
1509 if ( state->u_ocsp.server.file_expanded && olist
1510 && (Ustrcmp(olist, state->u_ocsp.server.file_expanded) == 0))
1512 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
1517 ocsp_free_response_list(state);
1518 state->u_ocsp.server.file_expanded = olist;
1522 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1524 if ((err = tls_add_certfile(sctx, state, file, errstr)))
1527 #ifndef DISABLE_OCSP
1529 if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1531 if (Ustrncmp(ofile, US"PEM ", 4) == 0)
1536 else if (Ustrncmp(ofile, US"DER ", 4) == 0)
1541 ocsp_load_response(state, ofile, fmt_pem);
1544 DEBUG(D_tls) debug_printf("ran out of ocsp file list\n");
1548 else /* would there ever be a need for multiple client certs? */
1549 if ((err = tls_add_certfile(sctx, state, expanded, errstr)))
1552 if ( state->privatekey
1553 && !expand_check(state->privatekey, US"tls_privatekey", &expanded, errstr))
1556 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1557 of the expansion is an empty string, ignore it also, and assume the private
1558 key is in the same file as the certificate. */
1560 if (expanded && *expanded)
1561 if (state->is_server)
1563 const uschar * file_list = expanded;
1567 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1568 if ((err = tls_add_pkeyfile(sctx, state, file, errstr)))
1571 else /* would there ever be a need for multiple client certs? */
1572 if ((err = tls_add_pkeyfile(sctx, state, expanded, errstr)))
1582 /**************************************************
1583 * One-time init credentials for server and client *
1584 **************************************************/
1587 server_load_ciphers(SSL_CTX * ctx, exim_openssl_state_st * state,
1588 uschar * ciphers, uschar ** errstr)
1590 for (uschar * s = ciphers; *s; s++ ) if (*s == '_') *s = '-';
1591 DEBUG(D_tls) debug_printf("required ciphers: %s\n", ciphers);
1592 if (!SSL_CTX_set_cipher_list(ctx, CS ciphers))
1593 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
1594 state->server_cipher_list = ciphers;
1601 lib_ctx_new(SSL_CTX ** ctxp, host_item * host, uschar ** errstr)
1604 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1605 if (!(ctx = SSL_CTX_new(host ? TLS_client_method() : TLS_server_method())))
1607 if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
1609 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
1611 /* Set up the information callback, which outputs if debugging is at a suitable
1616 SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
1617 #if defined(EXIM_HAVE_OPESSL_TRACE) && !defined(OPENSSL_NO_SSL_TRACE)
1618 /* this needs a debug build of OpenSSL */
1619 SSL_CTX_set_msg_callback(ctx, (void (*)())SSL_trace);
1621 #ifdef OPENSSL_HAVE_KEYLOG_CB
1622 SSL_CTX_set_keylog_callback(ctx, (void (*)())keylog_callback);
1626 /* Automatically re-try reads/writes after renegotiation. */
1627 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
1634 tls_server_creds_init(void)
1637 uschar * dummy_errstr;
1638 unsigned lifetime = 0;
1642 state_server.lib_state = null_tls_preload;
1644 if (lib_ctx_new(&ctx, NULL, &dummy_errstr) != OK)
1646 state_server.lib_state.lib_ctx = ctx;
1648 /* Preload DH params and EC curve */
1650 if (opt_unset_or_noexpand(tls_dhparam))
1652 DEBUG(D_tls) debug_printf("TLS: preloading DH params for server\n");
1653 if (init_dh(ctx, tls_dhparam, NULL, &dummy_errstr))
1654 state_server.lib_state.dh = TRUE;
1656 if (opt_unset_or_noexpand(tls_eccurve))
1658 DEBUG(D_tls) debug_printf("TLS: preloading ECDH curve for server\n");
1659 if (init_ecdh(ctx, NULL, &dummy_errstr))
1660 state_server.lib_state.ecdh = TRUE;
1663 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1664 /* If we can, preload the server-side cert, key and ocsp */
1666 if ( opt_set_and_noexpand(tls_certificate)
1667 # ifndef DISABLE_OCSP
1668 && opt_unset_or_noexpand(tls_ocsp_file)
1670 && opt_unset_or_noexpand(tls_privatekey))
1672 /* Set watches on the filenames. The implementation does de-duplication
1673 so we can just blindly do them all. */
1675 if ( tls_set_watch(tls_certificate, TRUE)
1676 # ifndef DISABLE_OCSP
1677 && tls_set_watch(tls_ocsp_file, TRUE)
1679 && tls_set_watch(tls_privatekey, TRUE))
1681 state_server.certificate = tls_certificate;
1682 state_server.privatekey = tls_privatekey;
1683 #ifndef DISABLE_OCSP
1684 state_server.u_ocsp.server.file = tls_ocsp_file;
1687 DEBUG(D_tls) debug_printf("TLS: preloading server certs\n");
1688 if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
1689 state_server.lib_state.conn_certs = TRUE;
1692 else if ( !tls_certificate && !tls_privatekey
1693 # ifndef DISABLE_OCSP
1697 { /* Generate & preload a selfsigned cert. No files to watch. */
1698 if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
1700 state_server.lib_state.conn_certs = TRUE;
1701 lifetime = f.running_in_test_harness ? 2 : 60 * 60; /* 1 hour */
1705 DEBUG(D_tls) debug_printf("TLS: not preloading server certs\n");
1708 /* If we can, preload the Authorities for checking client certs against.
1709 Actual choice to do verify is made (tls_{,try_}verify_hosts)
1710 at TLS conn startup */
1712 if ( opt_set_and_noexpand(tls_verify_certificates)
1713 && opt_unset_or_noexpand(tls_crl))
1715 /* Watch the default dir also as they are always included */
1717 if ( tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
1718 && tls_set_watch(tls_verify_certificates, FALSE)
1719 && tls_set_watch(tls_crl, FALSE))
1721 DEBUG(D_tls) debug_printf("TLS: preloading CA bundle for server\n");
1723 if (setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, &dummy_errstr)
1725 state_server.lib_state.cabundle = TRUE;
1729 DEBUG(D_tls) debug_printf("TLS: not preloading CA bundle for server\n");
1730 #endif /* EXIM_HAVE_INOTIFY */
1733 /* If we can, preload the ciphers control string */
1735 if (opt_set_and_noexpand(tls_require_ciphers))
1737 DEBUG(D_tls) debug_printf("TLS: preloading cipher list for server\n");
1738 if (server_load_ciphers(ctx, &state_server, tls_require_ciphers,
1739 &dummy_errstr) == OK)
1740 state_server.lib_state.pri_string = TRUE;
1743 DEBUG(D_tls) debug_printf("TLS: not preloading cipher list for server\n");
1750 /* Preload whatever creds are static, onto a transport. The client can then
1751 just copy the pointer as it starts up.
1752 Called from the daemon after a cache-invalidate with watch set; called from
1753 a queue-run startup with watch clear. */
1756 tls_client_creds_init(transport_instance * t, BOOL watch)
1758 smtp_transport_options_block * ob = t->options_block;
1759 exim_openssl_state_st tpt_dummy_state;
1760 host_item * dummy_host = (host_item *)1;
1761 uschar * dummy_errstr;
1766 ob->tls_preload = null_tls_preload;
1767 if (lib_ctx_new(&ctx, dummy_host, &dummy_errstr) != OK)
1769 ob->tls_preload.lib_ctx = ctx;
1771 tpt_dummy_state.lib_state = ob->tls_preload;
1773 if (opt_unset_or_noexpand(tls_dhparam))
1775 DEBUG(D_tls) debug_printf("TLS: preloading DH params for transport '%s'\n", t->name);
1776 if (init_dh(ctx, tls_dhparam, NULL, &dummy_errstr))
1777 ob->tls_preload.dh = TRUE;
1779 if (opt_unset_or_noexpand(tls_eccurve))
1781 DEBUG(D_tls) debug_printf("TLS: preloading ECDH curve for transport '%s'\n", t->name);
1782 if (init_ecdh(ctx, NULL, &dummy_errstr))
1783 ob->tls_preload.ecdh = TRUE;
1786 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1787 if ( opt_set_and_noexpand(ob->tls_certificate)
1788 && opt_unset_or_noexpand(ob->tls_privatekey))
1791 || ( tls_set_watch(ob->tls_certificate, FALSE)
1792 && tls_set_watch(ob->tls_privatekey, FALSE)
1795 uschar * pkey = ob->tls_privatekey;
1798 debug_printf("TLS: preloading client certs for transport '%s'\n",t->name);
1800 if ( tls_add_certfile(ctx, &tpt_dummy_state, ob->tls_certificate,
1802 && tls_add_pkeyfile(ctx, &tpt_dummy_state,
1803 pkey ? pkey : ob->tls_certificate,
1806 ob->tls_preload.conn_certs = TRUE;
1811 debug_printf("TLS: not preloading client certs, for transport '%s'\n", t->name);
1814 if ( opt_set_and_noexpand(ob->tls_verify_certificates)
1815 && opt_unset_or_noexpand(ob->tls_crl))
1818 || tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
1819 && tls_set_watch(ob->tls_verify_certificates, FALSE)
1820 && tls_set_watch(ob->tls_crl, FALSE)
1824 debug_printf("TLS: preloading CA bundle for transport '%s'\n", t->name);
1826 if (setup_certs(ctx, ob->tls_verify_certificates,
1827 ob->tls_crl, dummy_host, &dummy_errstr) == OK)
1828 ob->tls_preload.cabundle = TRUE;
1833 debug_printf("TLS: not preloading CA bundle, for transport '%s'\n", t->name);
1835 #endif /*EXIM_HAVE_INOTIFY*/
1839 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1840 /* Invalidate the creds cached, by dropping the current ones.
1841 Call when we notice one of the source files has changed. */
1844 tls_server_creds_invalidate(void)
1846 SSL_CTX_free(state_server.lib_state.lib_ctx);
1847 state_server.lib_state = null_tls_preload;
1852 tls_client_creds_invalidate(transport_instance * t)
1854 smtp_transport_options_block * ob = t->options_block;
1855 SSL_CTX_free(ob->tls_preload.lib_ctx);
1856 ob->tls_preload = null_tls_preload;
1862 tls_server_creds_invalidate(void)
1866 tls_client_creds_invalidate(transport_instance * t)
1869 #endif /*EXIM_HAVE_INOTIFY*/
1873 #ifndef DISABLE_OCSP
1875 x509_store_dump_cert_s_names(X509_STORE * store)
1877 STACK_OF(X509_OBJECT) * roots= store->objs;
1878 static uschar name[256];
1880 for (int i= 0; i < sk_X509_OBJECT_num(roots); i++)
1882 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
1883 if(tmp_obj->type == X509_LU_X509)
1885 X509_NAME * sn = X509_get_subject_name(tmp_obj->data.x509);
1886 if (X509_NAME_oneline(sn, CS name, sizeof(name)))
1888 name[sizeof(name)-1] = '\0';
1889 debug_printf(" %s\n", name);
1898 #ifndef DISABLE_TLS_RESUME
1899 /* Manage the keysets used for encrypting the session tickets, on the server. */
1901 typedef struct { /* Session ticket encryption key */
1904 const EVP_CIPHER * aes_cipher;
1905 uschar aes_key[32]; /* size needed depends on cipher. aes_128 implies 128/8 = 16? */
1906 const EVP_MD * hmac_hash;
1907 uschar hmac_key[16];
1912 static exim_stek exim_tk; /* current key */
1913 static exim_stek exim_tk_old; /* previous key */
1918 time_t t = time(NULL);
1920 if (exim_tk.name[0])
1922 if (exim_tk.renew >= t) return;
1923 exim_tk_old = exim_tk;
1926 if (f.running_in_test_harness) ssl_session_timeout = 6;
1928 DEBUG(D_tls) debug_printf("OpenSSL: %s STEK\n", exim_tk.name[0] ? "rotating" : "creating");
1929 if (RAND_bytes(exim_tk.aes_key, sizeof(exim_tk.aes_key)) <= 0) return;
1930 if (RAND_bytes(exim_tk.hmac_key, sizeof(exim_tk.hmac_key)) <= 0) return;
1931 if (RAND_bytes(exim_tk.name+1, sizeof(exim_tk.name)-1) <= 0) return;
1933 exim_tk.name[0] = 'E';
1934 exim_tk.aes_cipher = EVP_aes_256_cbc();
1935 exim_tk.hmac_hash = EVP_sha256();
1936 exim_tk.expire = t + ssl_session_timeout;
1937 exim_tk.renew = t + ssl_session_timeout/2;
1943 if (!exim_tk.name[0]) return NULL;
1948 tk_find(const uschar * name)
1950 return memcmp(name, exim_tk.name, sizeof(exim_tk.name)) == 0 ? &exim_tk
1951 : memcmp(name, exim_tk_old.name, sizeof(exim_tk_old.name)) == 0 ? &exim_tk_old
1955 /* Callback for session tickets, on server */
1957 ticket_key_callback(SSL * ssl, uschar key_name[16],
1958 uschar * iv, EVP_CIPHER_CTX * c_ctx, HMAC_CTX * hctx, int enc)
1960 tls_support * tlsp = state_server.tlsp;
1965 DEBUG(D_tls) debug_printf("ticket_key_callback: create new session\n");
1966 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
1968 if (RAND_bytes(iv, EVP_MAX_IV_LENGTH) <= 0)
1969 return -1; /* insufficient random */
1971 if (!(key = tk_current())) /* current key doesn't exist or isn't valid */
1972 return 0; /* key couldn't be created */
1973 memcpy(key_name, key->name, 16);
1974 DEBUG(D_tls) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - time(NULL));
1976 /*XXX will want these dependent on the ssl session strength */
1977 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
1978 key->hmac_hash, NULL);
1979 EVP_EncryptInit_ex(c_ctx, key->aes_cipher, NULL, key->aes_key, iv);
1981 DEBUG(D_tls) debug_printf("ticket created\n");
1986 time_t now = time(NULL);
1988 DEBUG(D_tls) debug_printf("ticket_key_callback: retrieve session\n");
1989 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
1991 if (!(key = tk_find(key_name)) || key->expire < now)
1995 debug_printf("ticket not usable (%s)\n", key ? "expired" : "not found");
1996 if (key) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - now);
2001 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
2002 key->hmac_hash, NULL);
2003 EVP_DecryptInit_ex(c_ctx, key->aes_cipher, NULL, key->aes_key, iv);
2005 DEBUG(D_tls) debug_printf("ticket usable, STEK expire " TIME_T_FMT "\n", key->expire - now);
2007 /* The ticket lifetime and renewal are the same as the STEK lifetime and
2008 renewal, which is overenthusiastic. A factor of, say, 3x longer STEK would
2009 be better. To do that we'd have to encode ticket lifetime in the name as
2010 we don't yet see the restored session. Could check posthandshake for TLS1.3
2011 and trigger a new ticket then, but cannot do that for TLS1.2 */
2012 return key->renew < now ? 2 : 1;
2020 setup_cert_verify(SSL_CTX * ctx, BOOL optional,
2021 int (*cert_vfy_cb)(int, X509_STORE_CTX *))
2023 /* If verification is optional, don't fail if no certificate */
2025 SSL_CTX_set_verify(ctx,
2026 SSL_VERIFY_PEER | (optional ? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
2031 /*************************************************
2032 * Callback to handle SNI *
2033 *************************************************/
2035 /* Called when acting as server during the TLS session setup if a Server Name
2036 Indication extension was sent by the client.
2038 API documentation is OpenSSL s_server.c implementation.
2041 s SSL* of the current session
2042 ad unknown (part of OpenSSL API) (unused)
2043 arg Callback of "our" registered data
2045 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
2047 XXX might need to change to using ClientHello callback,
2048 per https://www.openssl.org/docs/manmaster/man3/SSL_client_hello_cb_fn.html
2051 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2053 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
2055 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
2056 exim_openssl_state_st *state = (exim_openssl_state_st *) arg;
2058 int old_pool = store_pool;
2059 uschar * dummy_errstr;
2062 return SSL_TLSEXT_ERR_OK;
2064 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
2065 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
2067 /* Make the extension value available for expansion */
2068 store_pool = POOL_PERM;
2069 tls_in.sni = string_copy_taint(US servername, TRUE);
2070 store_pool = old_pool;
2072 if (!reexpand_tls_files_for_sni)
2073 return SSL_TLSEXT_ERR_OK;
2075 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
2076 not confident that memcpy wouldn't break some internal reference counting.
2077 Especially since there's a references struct member, which would be off. */
2079 if (lib_ctx_new(&server_sni, NULL, &dummy_errstr) != OK)
2082 /* Not sure how many of these are actually needed, since SSL object
2083 already exists. Might even need this selfsame callback, for reneg? */
2086 SSL_CTX * ctx = state_server.lib_state.lib_ctx;
2087 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(ctx));
2088 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(ctx));
2089 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(ctx));
2090 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(ctx));
2091 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
2092 SSL_CTX_set_tlsext_servername_arg(server_sni, state);
2095 if ( !init_dh(server_sni, state->dhparam, NULL, &dummy_errstr)
2096 || !init_ecdh(server_sni, NULL, &dummy_errstr)
2100 if ( state->server_cipher_list
2101 && !SSL_CTX_set_cipher_list(server_sni, CS state->server_cipher_list))
2104 #ifndef DISABLE_OCSP
2105 if (state->u_ocsp.server.file)
2107 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
2108 SSL_CTX_set_tlsext_status_arg(server_sni, state);
2114 if ( !expand_check(tls_verify_certificates, US"tls_verify_certificates",
2115 &expcerts, &dummy_errstr)
2116 || (rc = setup_certs(server_sni, expcerts, tls_crl, NULL,
2117 &dummy_errstr)) != OK)
2120 if (expcerts && *expcerts)
2121 setup_cert_verify(server_sni, FALSE, verify_callback_server);
2124 /* do this after setup_certs, because this can require the certs for verifying
2125 OCSP information. */
2126 if ((rc = tls_expand_session_files(server_sni, state, &dummy_errstr)) != OK)
2129 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
2130 SSL_set_SSL_CTX(s, server_sni);
2131 return SSL_TLSEXT_ERR_OK;
2133 bad: return SSL_TLSEXT_ERR_ALERT_FATAL;
2135 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
2140 #ifndef DISABLE_OCSP
2142 /*************************************************
2143 * Callback to handle OCSP Stapling *
2144 *************************************************/
2146 /* Called when acting as server during the TLS session setup if the client
2147 requests OCSP information with a Certificate Status Request.
2149 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
2155 tls_server_stapling_cb(SSL *s, void *arg)
2157 const exim_openssl_state_st * state = arg;
2158 ocsp_resplist * olist = state->u_ocsp.server.olist;
2159 uschar * response_der; /*XXX blob */
2160 int response_der_len;
2163 debug_printf("Received TLS status request (OCSP stapling); %s response list\n",
2164 olist ? "have" : "lack");
2166 tls_in.ocsp = OCSP_NOT_RESP;
2168 return SSL_TLSEXT_ERR_NOACK;
2170 #ifdef EXIM_HAVE_OPESSL_GET0_SERIAL
2172 const X509 * cert_sent = SSL_get_certificate(s);
2173 const ASN1_INTEGER * cert_serial = X509_get0_serialNumber(cert_sent);
2174 const BIGNUM * cert_bn = ASN1_INTEGER_to_BN(cert_serial, NULL);
2175 const X509_NAME * cert_issuer = X509_get_issuer_name(cert_sent);
2179 for (; olist; olist = olist->next)
2181 OCSP_BASICRESP * bs = OCSP_response_get1_basic(olist->resp);
2182 const OCSP_SINGLERESP * single = OCSP_resp_get0(bs, 0);
2183 const OCSP_CERTID * cid = OCSP_SINGLERESP_get0_id(single);
2184 ASN1_INTEGER * res_cert_serial;
2185 const BIGNUM * resp_bn;
2186 ASN1_OCTET_STRING * res_cert_iNameHash;
2189 (void) OCSP_id_get0_info(&res_cert_iNameHash, NULL, NULL, &res_cert_serial,
2190 (OCSP_CERTID *) cid);
2191 resp_bn = ASN1_INTEGER_to_BN(res_cert_serial, NULL);
2195 debug_printf("cert serial: %s\n", BN_bn2hex(cert_bn));
2196 debug_printf("resp serial: %s\n", BN_bn2hex(resp_bn));
2199 if (BN_cmp(cert_bn, resp_bn) == 0)
2201 DEBUG(D_tls) debug_printf("matched serial for ocsp\n");
2203 /*XXX TODO: check the rest of the list for duplicate matches.
2204 If any, need to also check the Issuer Name hash.
2205 Without this, we will provide the wrong status in the case of
2210 DEBUG(D_tls) debug_printf("not match serial for ocsp\n");
2214 DEBUG(D_tls) debug_printf("failed to find match for ocsp\n");
2215 return SSL_TLSEXT_ERR_NOACK;
2221 DEBUG(D_tls) debug_printf("OpenSSL version too early to support multi-leaf OCSP\n");
2222 return SSL_TLSEXT_ERR_NOACK;
2226 /*XXX could we do the i2d earlier, rather than during the callback? */
2227 response_der = NULL;
2228 response_der_len = i2d_OCSP_RESPONSE(olist->resp, &response_der);
2229 if (response_der_len <= 0)
2230 return SSL_TLSEXT_ERR_NOACK;
2232 SSL_set_tlsext_status_ocsp_resp(state_server.lib_state.lib_ssl,
2233 response_der, response_der_len);
2234 tls_in.ocsp = OCSP_VFIED;
2235 return SSL_TLSEXT_ERR_OK;
2240 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
2242 BIO_printf(bp, "\t%s: ", str);
2243 ASN1_GENERALIZEDTIME_print(bp, time);
2248 tls_client_stapling_cb(SSL *s, void *arg)
2250 exim_openssl_state_st * cbinfo = arg;
2251 const unsigned char * p;
2253 OCSP_RESPONSE * rsp;
2254 OCSP_BASICRESP * bs;
2257 DEBUG(D_tls) debug_printf("Received TLS status callback (OCSP stapling):\n");
2258 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
2261 /* Expect this when we requested ocsp but got none */
2262 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
2263 log_write(0, LOG_MAIN, "Required TLS certificate status not received");
2265 DEBUG(D_tls) debug_printf(" null\n");
2266 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2269 if (!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
2271 tls_out.ocsp = OCSP_FAILED; /*XXX should use tlsp-> to permit concurrent outbound */
2272 if (LOGGING(tls_cipher))
2273 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
2275 DEBUG(D_tls) debug_printf(" parse error\n");
2279 if (!(bs = OCSP_response_get1_basic(rsp)))
2281 tls_out.ocsp = OCSP_FAILED;
2282 if (LOGGING(tls_cipher))
2283 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
2285 DEBUG(D_tls) debug_printf(" error parsing response\n");
2286 OCSP_RESPONSE_free(rsp);
2290 /* We'd check the nonce here if we'd put one in the request. */
2291 /* However that would defeat cacheability on the server so we don't. */
2293 /* This section of code reworked from OpenSSL apps source;
2294 The OpenSSL Project retains copyright:
2295 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
2299 #ifndef EXIM_HAVE_OCSP_RESP_COUNT
2300 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
2303 DEBUG(D_tls) bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
2305 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
2307 /* Use the chain that verified the server cert to verify the stapled info */
2308 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
2310 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
2311 cbinfo->u_ocsp.client.verify_store, OCSP_NOEXPLICIT)) <= 0)
2312 if (ERR_peek_error())
2314 tls_out.ocsp = OCSP_FAILED;
2315 if (LOGGING(tls_cipher)) log_write(0, LOG_MAIN,
2316 "Received TLS cert status response, itself unverifiable: %s",
2317 ERR_reason_error_string(ERR_peek_error()));
2318 BIO_printf(bp, "OCSP response verify failure\n");
2319 ERR_print_errors(bp);
2320 OCSP_RESPONSE_print(bp, rsp, 0);
2324 DEBUG(D_tls) debug_printf("no explicit trust for OCSP signing"
2325 " in the root CA certificate; ignoring\n");
2327 DEBUG(D_tls) debug_printf("OCSP response well-formed and signed OK\n");
2329 /*XXX So we have a good stapled OCSP status. How do we know
2330 it is for the cert of interest? OpenSSL 1.1.0 has a routine
2331 OCSP_resp_find_status() which matches on a cert id, which presumably
2332 we should use. Making an id needs OCSP_cert_id_new(), which takes
2333 issuerName, issuerKey, serialNumber. Are they all in the cert?
2335 For now, carry on blindly accepting the resp. */
2338 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
2339 OCSP_resp_count(bs) - 1;
2341 sk_OCSP_SINGLERESP_num(sresp) - 1;
2345 OCSP_SINGLERESP * single = OCSP_resp_get0(bs, idx);
2347 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
2349 /*XXX so I can see putting a loop in here to handle a rsp with >1 singleresp
2350 - but what happens with a GnuTLS-style input?
2352 we could do with a debug label for each singleresp
2353 - it has a certID with a serialNumber, but I see no API to get that
2355 status = OCSP_single_get0_status(single, &reason, &rev,
2356 &thisupd, &nextupd);
2358 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
2359 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
2360 if (!OCSP_check_validity(thisupd, nextupd,
2361 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
2363 tls_out.ocsp = OCSP_FAILED;
2364 DEBUG(D_tls) ERR_print_errors(bp);
2365 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
2369 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
2370 OCSP_cert_status_str(status));
2373 case V_OCSP_CERTSTATUS_GOOD:
2374 continue; /* the idx loop */
2375 case V_OCSP_CERTSTATUS_REVOKED:
2376 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
2377 reason != -1 ? "; reason: " : "",
2378 reason != -1 ? OCSP_crl_reason_str(reason) : "");
2379 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
2382 log_write(0, LOG_MAIN,
2383 "Server certificate status unknown, in OCSP stapling");
2391 tls_out.ocsp = OCSP_VFIED;
2395 tls_out.ocsp = OCSP_FAILED;
2396 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2401 OCSP_RESPONSE_free(rsp);
2404 #endif /*!DISABLE_OCSP*/
2407 /*************************************************
2408 * Initialize for TLS *
2409 *************************************************/
2410 /* Called from both server and client code, to do preliminary initialization
2411 of the library. We allocate and return a context structure.
2414 host connected host, if client; NULL if server
2415 ob transport options block, if client; NULL if server
2416 ocsp_file file of stapling info (server); flag for require ocsp (client)
2417 addr address if client; NULL if server (for some randomness)
2418 caller_state place to put pointer to allocated state-struct
2419 errstr error string pointer
2421 Returns: OK/DEFER/FAIL
2425 tls_init(host_item * host, smtp_transport_options_block * ob,
2426 #ifndef DISABLE_OCSP
2429 address_item *addr, exim_openssl_state_st ** caller_state,
2434 exim_openssl_state_st * state;
2437 if (host) /* client */
2439 state = store_malloc(sizeof(exim_openssl_state_st));
2440 memset(state, 0, sizeof(*state));
2441 state->certificate = ob->tls_certificate;
2442 state->privatekey = ob->tls_privatekey;
2443 state->is_server = FALSE;
2444 state->dhparam = NULL;
2445 state->lib_state = ob->tls_preload;
2449 state = &state_server;
2450 state->certificate = tls_certificate;
2451 state->privatekey = tls_privatekey;
2452 state->is_server = TRUE;
2453 state->dhparam = tls_dhparam;
2454 state->lib_state = state_server.lib_state;
2460 if (!state->lib_state.pri_string)
2461 state->server_cipher_list = NULL;
2463 #ifndef DISABLE_EVENT
2464 state->event_action = NULL;
2469 /* It turns out that we need to seed the random number generator this early in
2470 order to get the full complement of ciphers to work. It took me roughly a day
2471 of work to discover this by experiment.
2473 On systems that have /dev/urandom, SSL may automatically seed itself from
2474 there. Otherwise, we have to make something up as best we can. Double check
2477 Although we likely called this before, at daemon startup, this is a chance
2478 to mix in further variable info (time, pid) if needed. */
2480 if (!lib_rand_init(addr))
2481 return tls_error(US"RAND_status", host,
2482 US"unable to seed random number generator", errstr);
2484 /* Apply administrator-supplied work-arounds.
2485 Historically we applied just one requested option,
2486 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
2487 moved to an administrator-controlled list of options to specify and
2488 grandfathered in the first one as the default value for "openssl_options".
2490 No OpenSSL version number checks: the options we accept depend upon the
2491 availability of the option value macros from OpenSSL. */
2494 if (!tls_openssl_options_parse(openssl_options, &init_options))
2495 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
2497 /* Create a context.
2498 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
2499 negotiation in the different methods; as far as I can tell, the only
2500 *_{server,client}_method which allows negotiation is SSLv23, which exists even
2501 when OpenSSL is built without SSLv2 support.
2502 By disabling with openssl_options, we can let admins re-enable with the
2505 if (!(ctx = state->lib_state.lib_ctx))
2507 if ((rc = lib_ctx_new(&ctx, host, errstr)) != OK)
2509 state->lib_state.lib_ctx = ctx;
2512 #ifndef DISABLE_TLS_RESUME
2513 tlsp->resumption = RESUME_SUPPORTED;
2517 #ifndef DISABLE_TLS_RESUME
2518 /* Should the server offer session resumption? */
2519 if (!host && verify_check_host(&tls_resumption_hosts) == OK)
2521 DEBUG(D_tls) debug_printf("tls_resumption_hosts overrides openssl_options\n");
2522 init_options &= ~SSL_OP_NO_TICKET;
2523 tlsp->resumption |= RESUME_SERVER_TICKET; /* server will give ticket on request */
2524 tlsp->host_resumable = TRUE;
2528 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
2529 if (!(SSL_CTX_set_options(ctx, init_options)))
2530 return tls_error(string_sprintf(
2531 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
2534 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
2536 /* We'd like to disable session cache unconditionally, but foolish Outlook
2537 Express clients then give up the first TLS connection and make a second one
2538 (which works). Only when there is an IMAP service on the same machine.
2539 Presumably OE is trying to use the cache for A on B. Leave it enabled for
2540 now, until we work out a decent way of presenting control to the config. It
2541 will never be used because we use a new context every time. */
2543 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
2546 /* Initialize with DH parameters if supplied */
2547 /* Initialize ECDH temp key parameter selection */
2549 if (state->lib_state.dh)
2550 { DEBUG(D_tls) debug_printf("TLS: DH params were preloaded\n"); }
2552 if (!init_dh(ctx, state->dhparam, host, errstr)) return DEFER;
2554 if (state->lib_state.ecdh)
2555 { DEBUG(D_tls) debug_printf("TLS: ECDH curve was preloaded\n"); }
2557 if (!init_ecdh(ctx, host, errstr)) return DEFER;
2559 /* Set up certificate and key (and perhaps OCSP info) */
2561 if (state->lib_state.conn_certs)
2564 debug_printf("TLS: %s certs were preloaded\n", host ? "client":"server");
2568 #ifndef DISABLE_OCSP
2571 state->u_ocsp.server.file = ocsp_file;
2572 state->u_ocsp.server.file_expanded = NULL;
2573 state->u_ocsp.server.olist = NULL;
2576 if ((rc = tls_expand_session_files(ctx, state, errstr)) != OK) return rc;
2579 /* If we need to handle SNI or OCSP, do so */
2581 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2582 # ifndef DISABLE_OCSP
2583 if (!(state->verify_stack = sk_X509_new_null()))
2585 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
2590 if (!host) /* server */
2592 # ifndef DISABLE_OCSP
2593 /* We check u_ocsp.server.file, not server.olist, because we care about if
2594 the option exists, not what the current expansion might be, as SNI might
2595 change the certificate and OCSP file in use between now and the time the
2596 callback is invoked. */
2597 if (state->u_ocsp.server.file)
2599 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
2600 SSL_CTX_set_tlsext_status_arg(ctx, state);
2603 /* We always do this, so that $tls_sni is available even if not used in
2605 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
2606 SSL_CTX_set_tlsext_servername_arg(ctx, state);
2608 # ifndef DISABLE_OCSP
2610 if(ocsp_file) /* wanting stapling */
2612 if (!(state->u_ocsp.client.verify_store = X509_STORE_new()))
2614 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
2617 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
2618 SSL_CTX_set_tlsext_status_arg(ctx, state);
2623 state->verify_cert_hostnames = NULL;
2625 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
2626 /* Set up the RSA callback */
2627 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
2630 /* Finally, set the session cache timeout, and we are done.
2631 The period appears to be also used for (server-generated) session tickets */
2633 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
2634 DEBUG(D_tls) debug_printf("Initialized TLS\n");
2636 *caller_state = state;
2644 /*************************************************
2645 * Get name of cipher in use *
2646 *************************************************/
2649 Argument: pointer to an SSL structure for the connection
2650 pointer to number of bits for cipher
2651 Returns: pointer to allocated string in perm-pool
2655 construct_cipher_name(SSL * ssl, const uschar * ver, int * bits)
2657 int pool = store_pool;
2658 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
2659 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
2660 the accessor functions use const in the prototype. */
2662 const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
2665 SSL_CIPHER_get_bits(c, bits);
2667 store_pool = POOL_PERM;
2668 s = string_sprintf("%s:%s:%u", ver, SSL_CIPHER_get_name(c), *bits);
2670 DEBUG(D_tls) debug_printf("Cipher: %s\n", s);
2675 /* Get IETF-standard name for ciphersuite.
2676 Argument: pointer to an SSL structure for the connection
2677 Returns: pointer to string
2680 static const uschar *
2681 cipher_stdname_ssl(SSL * ssl)
2683 #ifdef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
2684 return CUS SSL_CIPHER_standard_name(SSL_get_current_cipher(ssl));
2686 ushort id = 0xffff & SSL_CIPHER_get_id(SSL_get_current_cipher(ssl));
2687 return cipher_stdname(id >> 8, id & 0xff);
2692 static const uschar *
2693 tlsver_name(SSL * ssl)
2696 int pool = store_pool;
2698 store_pool = POOL_PERM;
2699 s = string_copy(US SSL_get_version(ssl));
2701 if ((p = Ustrchr(s, 'v'))) /* TLSv1.2 -> TLS1.2 */
2702 for (;; p++) if (!(*p = p[1])) break;
2708 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned siz)
2710 /*XXX we might consider a list-of-certs variable for the cert chain.
2711 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
2712 in list-handling functions, also consider the difference between the entire
2713 chain and the elements sent by the peer. */
2715 tlsp->peerdn = NULL;
2717 /* Will have already noted peercert on a verify fail; possibly not the leaf */
2718 if (!tlsp->peercert)
2719 tlsp->peercert = SSL_get_peer_certificate(ssl);
2720 /* Beware anonymous ciphers which lead to server_cert being NULL */
2722 if (!X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, siz))
2723 { DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n"); }
2726 int oldpool = store_pool;
2728 peerdn[siz-1] = '\0'; /* paranoia */
2729 store_pool = POOL_PERM;
2730 tlsp->peerdn = string_copy(peerdn);
2731 store_pool = oldpool;
2733 /* We used to set CV in the cert-verify callbacks (either plain or dane)
2734 but they don't get called on session-resumption. So use the official
2735 interface, which uses the resumed value. Unfortunately this claims verified
2736 when it actually failed but we're in try-verify mode, due to us wanting the
2737 knowlege that it failed so needing to have the callback and forcing a
2738 permissive return. If we don't force it, the TLS startup is failed.
2739 The extra bit of information is set in verify_override in the cb, stashed
2740 for resumption next to the TLS session, and used here. */
2742 if (!tlsp->verify_override)
2743 tlsp->certificate_verified =
2745 tlsp->dane_verified ||
2747 SSL_get_verify_result(ssl) == X509_V_OK;
2755 /*************************************************
2756 * Set up for verifying certificates *
2757 *************************************************/
2759 #ifndef DISABLE_OCSP
2760 /* Load certs from file, return TRUE on success */
2763 chain_from_pem_file(const uschar * file, STACK_OF(X509) * verify_stack)
2768 while (sk_X509_num(verify_stack) > 0)
2769 X509_free(sk_X509_pop(verify_stack));
2771 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
2772 while ((x = PEM_read_bio_X509(bp, NULL, 0, NULL)))
2773 sk_X509_push(verify_stack, x);
2781 /* Called by both client and server startup; on the server possibly
2782 repeated after a Server Name Indication.
2785 sctx SSL_CTX* to initialise
2786 certs certs file, expanded
2787 crl CRL file or NULL
2788 host NULL in a server; the remote host in a client
2789 errstr error string pointer
2791 Returns: OK/DEFER/FAIL
2795 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host,
2798 uschar *expcerts, *expcrl;
2800 if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
2802 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
2804 if (expcerts && *expcerts)
2806 /* Tell the library to use its compiled-in location for the system default
2807 CA bundle. Then add the ones specified in the config, if any. */
2809 if (!SSL_CTX_set_default_verify_paths(sctx))
2810 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
2812 if (Ustrcmp(expcerts, "system") != 0 && Ustrncmp(expcerts, "system,", 7) != 0)
2814 struct stat statbuf;
2816 if (Ustat(expcerts, &statbuf) < 0)
2818 log_write(0, LOG_MAIN|LOG_PANIC,
2819 "failed to stat %s for certificates", expcerts);
2825 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
2826 { file = NULL; dir = expcerts; }
2829 file = expcerts; dir = NULL;
2830 #ifndef DISABLE_OCSP
2831 /* In the server if we will be offering an OCSP proof, load chain from
2832 file for verifying the OCSP proof at load time. */
2834 /*XXX Glitch! The file here is tls_verify_certs: the chain for verifying the client cert.
2835 This is inconsistent with the need to verify the OCSP proof of the server cert.
2839 && statbuf.st_size > 0
2840 && state_server.u_ocsp.server.file
2841 && !chain_from_pem_file(file, state_server.verify_stack)
2844 log_write(0, LOG_MAIN|LOG_PANIC,
2845 "failed to load cert chain from %s", file);
2851 /* If a certificate file is empty, the load function fails with an
2852 unhelpful error message. If we skip it, we get the correct behaviour (no
2853 certificates are recognized, but the error message is still misleading (it
2854 says no certificate was supplied). But this is better. */
2856 if ( (!file || statbuf.st_size > 0)
2857 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
2858 return tls_error(US"SSL_CTX_load_verify_locations",
2859 host, NULL, errstr);
2861 /* On the server load the list of CAs for which we will accept certs, for
2862 sending to the client. This is only for the one-file
2863 tls_verify_certificates variant.
2864 If a list isn't loaded into the server, but some verify locations are set,
2865 the server end appears to make a wildcard request for client certs.
2866 Meanwhile, the client library as default behaviour *ignores* the list
2867 we send over the wire - see man SSL_CTX_set_client_cert_cb.
2868 Because of this, and that the dir variant is likely only used for
2869 the public-CA bundle (not for a private CA), not worth fixing. */
2873 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
2874 int i = sk_X509_NAME_num(names);
2876 if (!host) SSL_CTX_set_client_CA_list(sctx, names);
2877 DEBUG(D_tls) debug_printf("Added %d additional certificate authorit%s\n",
2878 i, i>1 ? "ies":"y");
2882 debug_printf("Added dir for additional certificate authorities\n");
2886 /* Handle a certificate revocation list. */
2888 #if OPENSSL_VERSION_NUMBER > 0x00907000L
2890 /* This bit of code is now the version supplied by Lars Mainka. (I have
2891 merely reformatted it into the Exim code style.)
2893 "From here I changed the code to add support for multiple crl's
2894 in pem format in one file or to support hashed directory entries in
2895 pem format instead of a file. This method now uses the library function
2896 X509_STORE_load_locations to add the CRL location to the SSL context.
2897 OpenSSL will then handle the verify against CA certs and CRLs by
2898 itself in the verify callback." */
2900 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
2901 if (expcrl && *expcrl)
2903 struct stat statbufcrl;
2904 if (Ustat(expcrl, &statbufcrl) < 0)
2906 log_write(0, LOG_MAIN|LOG_PANIC,
2907 "failed to stat %s for certificates revocation lists", expcrl);
2912 /* is it a file or directory? */
2914 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
2915 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
2919 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
2925 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
2927 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
2928 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
2930 /* setting the flags to check against the complete crl chain */
2932 X509_STORE_set_flags(cvstore,
2933 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
2937 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
2945 /*************************************************
2946 * Start a TLS session in a server *
2947 *************************************************/
2948 /* This is called when Exim is running as a server, after having received
2949 the STARTTLS command. It must respond to that command, and then negotiate
2953 errstr pointer to error message
2955 Returns: OK on success
2956 DEFER for errors before the start of the negotiation
2957 FAIL for errors during the negotiation; the server can't
2962 tls_server_start(uschar ** errstr)
2965 uschar * expciphers;
2966 exim_openssl_state_st * dummy_statep;
2969 static uschar peerdn[256];
2971 /* Check for previous activation */
2973 if (tls_in.active.sock >= 0)
2975 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
2976 smtp_printf("554 Already in TLS\r\n", FALSE);
2980 /* Initialize the SSL library. If it fails, it will already have logged
2983 rc = tls_init(NULL, NULL,
2984 #ifndef DISABLE_OCSP
2987 NULL, &dummy_statep, &tls_in, errstr);
2988 if (rc != OK) return rc;
2989 ctx = state_server.lib_state.lib_ctx;
2991 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2992 were historically separated by underscores. So that I can use either form in my
2993 tests, and also for general convenience, we turn underscores into hyphens here.
2995 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
2996 for TLS 1.3 . Since we do not call it at present we get the default list:
2997 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
3000 if (state_server.lib_state.pri_string)
3001 { DEBUG(D_tls) debug_printf("TLS: cipher list was preloaded\n"); }
3004 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
3008 && (rc = server_load_ciphers(ctx, &state_server, expciphers, errstr)) != OK)
3012 /* If this is a host for which certificate verification is mandatory or
3013 optional, set up appropriately. */
3015 tls_in.certificate_verified = FALSE;
3017 tls_in.dane_verified = FALSE;
3019 server_verify_callback_called = FALSE;
3021 if (verify_check_host(&tls_verify_hosts) == OK)
3022 server_verify_optional = FALSE;
3023 else if (verify_check_host(&tls_try_verify_hosts) == OK)
3024 server_verify_optional = TRUE;
3030 if (!expand_check(tls_verify_certificates, US"tls_verify_certificates",
3033 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3035 if (state_server.lib_state.cabundle)
3036 { DEBUG(D_tls) debug_printf("TLS: CA bundle for server was preloaded\n"); }
3038 if ((rc = setup_certs(ctx, expcerts, tls_crl, NULL, errstr)) != OK)
3041 if (expcerts && *expcerts)
3042 setup_cert_verify(ctx, server_verify_optional, verify_callback_server);
3046 #ifndef DISABLE_TLS_RESUME
3047 SSL_CTX_set_tlsext_ticket_key_cb(ctx, ticket_key_callback);
3048 /* despite working, appears to always return failure, so ignoring */
3050 #ifdef OPENSSL_HAVE_NUM_TICKETS
3051 # ifndef DISABLE_TLS_RESUME
3052 SSL_CTX_set_num_tickets(ctx, tls_in.host_resumable ? 1 : 0);
3054 SSL_CTX_set_num_tickets(ctx, 0); /* send no TLS1.3 stateful-tickets */
3059 /* Prepare for new connection */
3061 if (!(ssl = SSL_new(ctx)))
3062 return tls_error(US"SSL_new", NULL, NULL, errstr);
3063 state_server.lib_state.lib_ssl = ssl;
3065 /* Warning: we used to SSL_clear(ssl) here, it was removed.
3067 * With the SSL_clear(), we get strange interoperability bugs with
3068 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
3069 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
3071 * The SSL_clear() call is to let an existing SSL* be reused, typically after
3072 * session shutdown. In this case, we have a brand new object and there's no
3073 * obvious reason to immediately clear it. I'm guessing that this was
3074 * originally added because of incomplete initialisation which the clear fixed,
3075 * in some historic release.
3078 /* Set context and tell client to go ahead, except in the case of TLS startup
3079 on connection, where outputting anything now upsets the clients and tends to
3080 make them disconnect. We need to have an explicit fflush() here, to force out
3081 the response. Other smtp_printf() calls do not need it, because in non-TLS
3082 mode, the fflush() happens when smtp_getc() is called. */
3084 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
3085 if (!tls_in.on_connect)
3087 smtp_printf("220 TLS go ahead\r\n", FALSE);
3091 /* Now negotiate the TLS session. We put our own timer on it, since it seems
3092 that the OpenSSL library doesn't. */
3094 SSL_set_wfd(ssl, fileno(smtp_out));
3095 SSL_set_rfd(ssl, fileno(smtp_in));
3096 SSL_set_accept_state(ssl);
3098 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
3101 sigalrm_seen = FALSE;
3102 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3103 rc = SSL_accept(ssl);
3108 int error = SSL_get_error(ssl, rc);
3111 case SSL_ERROR_NONE:
3114 case SSL_ERROR_ZERO_RETURN:
3115 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3116 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
3118 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
3121 tls_close(NULL, TLS_NO_SHUTDOWN);
3124 /* Handle genuine errors */
3128 int r = ERR_GET_REASON(ERR_peek_error());
3129 if ( r == SSL_R_WRONG_VERSION_NUMBER
3130 #ifdef SSL_R_VERSION_TOO_LOW
3131 || r == SSL_R_VERSION_TOO_LOW
3133 || r == SSL_R_UNKNOWN_PROTOCOL || r == SSL_R_UNSUPPORTED_PROTOCOL)
3134 s = string_sprintf("%s (%s)", s, SSL_get_version(ssl));
3135 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : s, errstr);
3140 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
3141 if (error == SSL_ERROR_SYSCALL)
3145 *errstr = US"SSL_accept: TCP connection closed by peer";
3148 DEBUG(D_tls) debug_printf(" - syscall %s\n", strerror(errno));
3150 (void) tls_error(US"SSL_accept", NULL,
3151 sigalrm_seen ? US"timed out"
3152 : ERR_peek_error() ? NULL : string_sprintf("ret %d", error),
3158 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
3159 ERR_clear_error(); /* Even success can leave errors in the stack. Seen with
3160 anon-authentication ciphersuite negotiated. */
3162 #ifndef DISABLE_TLS_RESUME
3163 if (SSL_session_reused(ssl))
3165 tls_in.resumption |= RESUME_USED;
3166 DEBUG(D_tls) debug_printf("Session reused\n");
3170 /* TLS has been set up. Record data for the connection,
3171 adjust the input functions to read via TLS, and initialize things. */
3173 #ifdef SSL_get_extms_support
3174 tls_in.ext_master_secret = SSL_get_extms_support(ssl) == 1;
3176 peer_cert(ssl, &tls_in, peerdn, sizeof(peerdn));
3178 tls_in.ver = tlsver_name(ssl);
3179 tls_in.cipher = construct_cipher_name(ssl, tls_in.ver, &tls_in.bits);
3180 tls_in.cipher_stdname = cipher_stdname_ssl(ssl);
3185 if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)))
3186 debug_printf("Shared ciphers: %s\n", buf);
3188 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3190 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
3191 SSL_SESSION_print_keylog(bp, SSL_get_session(ssl));
3196 #ifdef EXIM_HAVE_SESSION_TICKET
3198 SSL_SESSION * ss = SSL_get_session(ssl);
3199 if (SSL_SESSION_has_ticket(ss)) /* 1.1.0 */
3200 debug_printf("The session has a ticket, life %lu seconds\n",
3201 SSL_SESSION_get_ticket_lifetime_hint(ss));
3206 /* Record the certificate we presented */
3208 X509 * crt = SSL_get_certificate(ssl);
3209 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
3212 /* Channel-binding info for authenticators
3213 See description in https://paquier.xyz/postgresql-2/channel-binding-openssl/ */
3216 size_t len = SSL_get_peer_finished(ssl, &c, 0);
3217 int old_pool = store_pool;
3219 SSL_get_peer_finished(ssl, s = store_get((int)len, FALSE), len);
3220 store_pool = POOL_PERM;
3221 tls_in.channelbinding = b64encode_taint(CUS s, (int)len, FALSE);
3222 store_pool = old_pool;
3223 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage %p\n", tls_in.channelbinding);
3226 /* Only used by the server-side tls (tls_in), including tls_getc.
3227 Client-side (tls_out) reads (seem to?) go via
3228 smtp_read_response()/ip_recv().
3229 Hence no need to duplicate for _in and _out.
3231 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
3232 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
3233 ssl_xfer_eof = ssl_xfer_error = FALSE;
3235 receive_getc = tls_getc;
3236 receive_getbuf = tls_getbuf;
3237 receive_get_cache = tls_get_cache;
3238 receive_ungetc = tls_ungetc;
3239 receive_feof = tls_feof;
3240 receive_ferror = tls_ferror;
3241 receive_smtp_buffered = tls_smtp_buffered;
3243 tls_in.active.sock = fileno(smtp_out);
3244 tls_in.active.tls_ctx = NULL; /* not using explicit ctx for server-side */
3252 tls_client_basic_ctx_init(SSL_CTX * ctx,
3253 host_item * host, smtp_transport_options_block * ob, exim_openssl_state_st * state,
3258 /* Back-compatible old behaviour if tls_verify_certificates is set but both
3259 tls_verify_hosts and tls_try_verify_hosts are not set. Check only the specified
3260 host patterns if one of them is set with content. */
3262 if ( ( ( !ob->tls_verify_hosts || !ob->tls_verify_hosts
3263 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3265 && ( !ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts
3266 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3269 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
3271 client_verify_optional = FALSE;
3272 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
3273 client_verify_optional = TRUE;
3279 if (!expand_check(ob->tls_verify_certificates, US"tls_verify_certificates",
3282 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3284 if (state->lib_state.cabundle)
3285 { DEBUG(D_tls) debug_printf("TLS: CA bundle was preloaded\n"); }
3287 if ((rc = setup_certs(ctx, expcerts, ob->tls_crl, host, errstr)) != OK)
3290 if (expcerts && *expcerts)
3291 setup_cert_verify(ctx, client_verify_optional, verify_callback_client);
3294 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
3296 state->verify_cert_hostnames =
3298 string_domain_utf8_to_alabel(host->certname, NULL);
3302 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
3303 state->verify_cert_hostnames);
3311 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
3314 const char * hostnames[2] = { CS host->name, NULL };
3317 if (DANESSL_init(ssl, NULL, hostnames) != 1)
3318 return tls_error(US"hostnames load", host, NULL, errstr);
3320 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
3321 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
3322 ) if (rr->type == T_TLSA && rr->size > 3)
3324 const uschar * p = rr->data;
3325 uint8_t usage, selector, mtype;
3326 const char * mdname;
3330 /* Only DANE-TA(2) and DANE-EE(3) are supported */
3331 if (usage != 2 && usage != 3) continue;
3338 default: continue; /* Only match-types 0, 1, 2 are supported */
3339 case 0: mdname = NULL; break;
3340 case 1: mdname = "sha256"; break;
3341 case 2: mdname = "sha512"; break;
3345 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
3348 return tls_error(US"tlsa load", host, NULL, errstr);
3349 case 0: /* action not taken */
3353 tls_out.tlsa_usage |= 1<<usage;
3359 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
3362 #endif /*SUPPORT_DANE*/
3366 #ifndef DISABLE_TLS_RESUME
3367 /* On the client, get any stashed session for the given IP from hints db
3368 and apply it to the ssl-connection for attempted resumption. */
3371 tls_retrieve_session(tls_support * tlsp, SSL * ssl, const uschar * key)
3373 tlsp->resumption |= RESUME_SUPPORTED;
3374 if (tlsp->host_resumable)
3376 dbdata_tls_session * dt;
3378 open_db dbblock, * dbm_file;
3380 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
3381 DEBUG(D_tls) debug_printf("checking for resumable session for %s\n", key);
3382 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3384 /* key for the db is the IP */
3385 if ((dt = dbfn_read_with_length(dbm_file, key, &len)))
3387 SSL_SESSION * ss = NULL;
3388 const uschar * sess_asn1 = dt->session;
3390 len -= sizeof(dbdata_tls_session);
3391 if (!(d2i_SSL_SESSION(&ss, &sess_asn1, (long)len)))
3395 ERR_error_string_n(ERR_get_error(),
3396 ssl_errstring, sizeof(ssl_errstring));
3397 debug_printf("decoding session: %s\n", ssl_errstring);
3400 #ifdef EXIM_HAVE_SESSION_TICKET
3401 else if ( SSL_SESSION_get_ticket_lifetime_hint(ss) + dt->time_stamp
3404 DEBUG(D_tls) debug_printf("session expired\n");
3405 dbfn_delete(dbm_file, key);
3408 else if (!SSL_set_session(ssl, ss))
3412 ERR_error_string_n(ERR_get_error(),
3413 ssl_errstring, sizeof(ssl_errstring));
3414 debug_printf("applying session to ssl: %s\n", ssl_errstring);
3419 DEBUG(D_tls) debug_printf("good session\n");
3420 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
3421 tlsp->verify_override = dt->verify_override;
3422 tlsp->ocsp = dt->ocsp;
3426 DEBUG(D_tls) debug_printf("no session record\n");
3427 dbfn_close(dbm_file);
3433 /* On the client, save the session for later resumption */
3436 tls_save_session_cb(SSL * ssl, SSL_SESSION * ss)
3438 exim_openssl_state_st * cbinfo = SSL_get_ex_data(ssl, tls_exdata_idx);
3441 DEBUG(D_tls) debug_printf("tls_save_session_cb\n");
3443 if (!cbinfo || !(tlsp = cbinfo->tlsp)->host_resumable) return 0;
3445 # ifdef OPENSSL_HAVE_NUM_TICKETS
3446 if (SSL_SESSION_is_resumable(ss)) /* 1.1.1 */
3449 int len = i2d_SSL_SESSION(ss, NULL);
3450 int dlen = sizeof(dbdata_tls_session) + len;
3451 dbdata_tls_session * dt = store_get(dlen, TRUE);
3452 uschar * s = dt->session;
3453 open_db dbblock, * dbm_file;
3455 DEBUG(D_tls) debug_printf("session is resumable\n");
3456 tlsp->resumption |= RESUME_SERVER_TICKET; /* server gave us a ticket */
3458 dt->verify_override = tlsp->verify_override;
3459 dt->ocsp = tlsp->ocsp;
3460 (void) i2d_SSL_SESSION(ss, &s); /* s gets bumped to end */
3462 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3464 const uschar * key = cbinfo->host->address;
3465 dbfn_delete(dbm_file, key);
3466 dbfn_write(dbm_file, key, dt, dlen);
3467 dbfn_close(dbm_file);
3468 DEBUG(D_tls) debug_printf("wrote session (len %u) to db\n",
3477 tls_client_ctx_resume_prehandshake(
3478 exim_openssl_client_tls_ctx * exim_client_ctx, tls_support * tlsp,
3479 smtp_transport_options_block * ob, host_item * host)
3481 /* Should the client request a session resumption ticket? */
3482 if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
3484 tlsp->host_resumable = TRUE;
3486 SSL_CTX_set_session_cache_mode(exim_client_ctx->ctx,
3487 SSL_SESS_CACHE_CLIENT
3488 | SSL_SESS_CACHE_NO_INTERNAL | SSL_SESS_CACHE_NO_AUTO_CLEAR);
3489 SSL_CTX_sess_set_new_cb(exim_client_ctx->ctx, tls_save_session_cb);
3494 tls_client_ssl_resume_prehandshake(SSL * ssl, tls_support * tlsp,
3495 host_item * host, uschar ** errstr)
3497 if (tlsp->host_resumable)
3500 debug_printf("tls_resumption_hosts overrides openssl_options, enabling tickets\n");
3501 SSL_clear_options(ssl, SSL_OP_NO_TICKET);
3503 tls_exdata_idx = SSL_get_ex_new_index(0, 0, 0, 0, 0);
3504 if (!SSL_set_ex_data(ssl, tls_exdata_idx, client_static_state))
3506 tls_error(US"set ex_data", host, NULL, errstr);
3509 debug_printf("tls_exdata_idx %d cbinfo %p\n", tls_exdata_idx, client_static_state);
3512 tlsp->resumption = RESUME_SUPPORTED;
3513 /* Pick up a previous session, saved on an old ticket */
3514 tls_retrieve_session(tlsp, ssl, host->address);
3519 tls_client_resume_posthandshake(exim_openssl_client_tls_ctx * exim_client_ctx,
3522 if (SSL_session_reused(exim_client_ctx->ssl))
3524 DEBUG(D_tls) debug_printf("The session was reused\n");
3525 tlsp->resumption |= RESUME_USED;
3528 #endif /* !DISABLE_TLS_RESUME */
3531 /*************************************************
3532 * Start a TLS session in a client *
3533 *************************************************/
3535 /* Called from the smtp transport after STARTTLS has been accepted.
3538 cctx connection context
3539 conn_args connection details
3540 cookie datum for randomness; can be NULL
3541 tlsp record details of TLS channel configuration here; must be non-NULL
3542 errstr error string pointer
3544 Returns: TRUE for success with TLS session context set in connection context,
3549 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
3550 void * cookie, tls_support * tlsp, uschar ** errstr)
3552 host_item * host = conn_args->host; /* for msgs and option-tests */
3553 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
3554 smtp_transport_options_block * ob = tb
3555 ? (smtp_transport_options_block *)tb->options_block
3556 : &smtp_transport_option_defaults;
3557 exim_openssl_client_tls_ctx * exim_client_ctx;
3558 uschar * expciphers;
3560 static uschar peerdn[256];
3562 #ifndef DISABLE_OCSP
3563 BOOL request_ocsp = FALSE;
3564 BOOL require_ocsp = FALSE;
3568 store_pool = POOL_PERM;
3569 exim_client_ctx = store_get(sizeof(exim_openssl_client_tls_ctx), FALSE);
3570 exim_client_ctx->corked = NULL;
3574 tlsp->tlsa_usage = 0;
3577 #ifndef DISABLE_OCSP
3579 # ifdef SUPPORT_DANE
3580 /*XXX this should be moved to caller, to be common across gnutls/openssl */
3581 if ( conn_args->dane
3582 && ob->hosts_request_ocsp[0] == '*'
3583 && ob->hosts_request_ocsp[1] == '\0'
3586 /* Unchanged from default. Use a safer one under DANE */
3587 request_ocsp = TRUE;
3588 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
3589 " {= {4}{$tls_out_tlsa_usage}} } "
3595 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK))
3596 request_ocsp = TRUE;
3598 # ifdef SUPPORT_DANE
3602 verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3606 rc = tls_init(host, ob,
3607 #ifndef DISABLE_OCSP
3608 (void *)(long)request_ocsp,
3610 cookie, &client_static_state, tlsp, errstr);
3611 if (rc != OK) return FALSE;
3613 exim_client_ctx->ctx = client_static_state->lib_state.lib_ctx;
3615 tlsp->certificate_verified = FALSE;
3616 client_verify_callback_called = FALSE;
3620 if (conn_args->dane)
3622 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
3623 other failures should be treated as problems. */
3624 if (ob->dane_require_tls_ciphers &&
3625 !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
3626 &expciphers, errstr))
3628 if (expciphers && *expciphers == '\0')
3633 !expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
3634 &expciphers, errstr))
3637 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
3638 are separated by underscores. So that I can use either form in my tests, and
3639 also for general convenience, we turn underscores into hyphens here. */
3643 uschar *s = expciphers;
3644 while (*s) { if (*s == '_') *s = '-'; s++; }
3645 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
3646 if (!SSL_CTX_set_cipher_list(exim_client_ctx->ctx, CS expciphers))
3648 tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
3654 if (conn_args->dane)
3656 SSL_CTX_set_verify(exim_client_ctx->ctx,
3657 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
3658 verify_callback_client_dane);
3660 if (!DANESSL_library_init())
3662 tls_error(US"library init", host, NULL, errstr);
3665 if (DANESSL_CTX_init(exim_client_ctx->ctx) <= 0)
3667 tls_error(US"context init", host, NULL, errstr);
3675 if (tls_client_basic_ctx_init(exim_client_ctx->ctx, host, ob,
3676 client_static_state, errstr) != OK)
3679 #ifndef DISABLE_TLS_RESUME
3680 tls_client_ctx_resume_prehandshake(exim_client_ctx, tlsp, ob, host);
3684 if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx)))
3686 tls_error(US"SSL_new", host, NULL, errstr);
3689 SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx));
3691 SSL_set_fd(exim_client_ctx->ssl, cctx->sock);
3692 SSL_set_connect_state(exim_client_ctx->ssl);
3696 if (!expand_check(ob->tls_sni, US"tls_sni", &tlsp->sni, errstr))
3700 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
3702 else if (!Ustrlen(tlsp->sni))
3706 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
3707 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tlsp->sni);
3708 SSL_set_tlsext_host_name(exim_client_ctx->ssl, tlsp->sni);
3710 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
3717 if (conn_args->dane)
3718 if (dane_tlsa_load(exim_client_ctx->ssl, host, &conn_args->tlsa_dnsa, errstr) != OK)
3722 #ifndef DISABLE_OCSP
3723 /* Request certificate status at connection-time. If the server
3724 does OCSP stapling we will get the callback (set in tls_init()) */
3725 # ifdef SUPPORT_DANE
3729 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
3730 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
3732 { /* Re-eval now $tls_out_tlsa_usage is populated. If
3733 this means we avoid the OCSP request, we wasted the setup
3734 cost in tls_init(). */
3735 require_ocsp = verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
3736 request_ocsp = require_ocsp
3737 || verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3744 SSL_set_tlsext_status_type(exim_client_ctx->ssl, TLSEXT_STATUSTYPE_ocsp);
3745 client_static_state->u_ocsp.client.verify_required = require_ocsp;
3746 tlsp->ocsp = OCSP_NOT_RESP;
3750 #ifndef DISABLE_TLS_RESUME
3751 if (!tls_client_ssl_resume_prehandshake(exim_client_ctx->ssl, tlsp, host,
3756 #ifndef DISABLE_EVENT
3757 client_static_state->event_action = tb ? tb->event_action : NULL;
3760 /* There doesn't seem to be a built-in timeout on connection. */
3762 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
3763 sigalrm_seen = FALSE;
3764 ALARM(ob->command_timeout);
3765 rc = SSL_connect(exim_client_ctx->ssl);
3769 if (conn_args->dane)
3770 DANESSL_cleanup(exim_client_ctx->ssl);
3775 tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, errstr);
3781 debug_printf("SSL_connect succeeded\n");
3782 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3784 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
3785 SSL_SESSION_print_keylog(bp, SSL_get_session(exim_client_ctx->ssl));
3791 #ifndef DISABLE_TLS_RESUME
3792 tls_client_resume_posthandshake(exim_client_ctx, tlsp);
3795 #ifdef SSL_get_extms_support
3796 tlsp->ext_master_secret = SSL_get_extms_support(exim_client_ctx->ssl) == 1;
3798 peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn));
3800 tlsp->ver = tlsver_name(exim_client_ctx->ssl);
3801 tlsp->cipher = construct_cipher_name(exim_client_ctx->ssl, tlsp->ver, &tlsp->bits);
3802 tlsp->cipher_stdname = cipher_stdname_ssl(exim_client_ctx->ssl);
3804 /* Record the certificate we presented */
3806 X509 * crt = SSL_get_certificate(exim_client_ctx->ssl);
3807 tlsp->ourcert = crt ? X509_dup(crt) : NULL;
3810 /*XXX will this work with continued-TLS? */
3811 /* Channel-binding info for authenticators */
3814 size_t len = SSL_get_finished(exim_client_ctx->ssl, &c, 0);
3815 int old_pool = store_pool;
3817 SSL_get_finished(exim_client_ctx->ssl, s = store_get((int)len, TRUE), len);
3818 store_pool = POOL_PERM;
3819 tlsp->channelbinding = b64encode_taint(CUS s, (int)len, TRUE);
3820 store_pool = old_pool;
3821 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage %p %p\n", tlsp->channelbinding, tlsp);
3824 tlsp->active.sock = cctx->sock;
3825 tlsp->active.tls_ctx = exim_client_ctx;
3826 cctx->tls_ctx = exim_client_ctx;
3835 tls_refill(unsigned lim)
3837 SSL * ssl = state_server.lib_state.lib_ssl;
3841 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
3842 ssl_xfer_buffer, ssl_xfer_buffer_size);
3845 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3846 inbytes = SSL_read(ssl, CS ssl_xfer_buffer,
3847 MIN(ssl_xfer_buffer_size, lim));
3848 error = SSL_get_error(ssl, inbytes);
3849 if (smtp_receive_timeout > 0) ALARM_CLR(0);
3851 if (had_command_timeout) /* set by signal handler */
3852 smtp_command_timeout_exit(); /* does not return */
3853 if (had_command_sigterm)
3854 smtp_command_sigterm_exit();
3855 if (had_data_timeout)
3856 smtp_data_timeout_exit();
3857 if (had_data_sigint)
3858 smtp_data_sigint_exit();
3860 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
3861 closed down, not that the socket itself has been closed down. Revert to
3862 non-SSL handling. */
3866 case SSL_ERROR_NONE:
3869 case SSL_ERROR_ZERO_RETURN:
3870 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3872 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
3875 tls_close(NULL, TLS_NO_SHUTDOWN);
3878 /* Handle genuine errors */
3880 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3881 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
3882 ssl_xfer_error = TRUE;
3886 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
3887 DEBUG(D_tls) if (error == SSL_ERROR_SYSCALL)
3888 debug_printf(" - syscall %s\n", strerror(errno));
3889 ssl_xfer_error = TRUE;
3893 #ifndef DISABLE_DKIM
3894 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
3896 ssl_xfer_buffer_hwm = inbytes;
3897 ssl_xfer_buffer_lwm = 0;
3902 /*************************************************
3903 * TLS version of getc *
3904 *************************************************/
3906 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
3907 it refills the buffer via the SSL reading function.
3909 Arguments: lim Maximum amount to read/buffer
3910 Returns: the next character or EOF
3912 Only used by the server-side TLS.
3916 tls_getc(unsigned lim)
3918 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
3919 if (!tls_refill(lim))
3920 return ssl_xfer_error ? EOF : smtp_getc(lim);
3922 /* Something in the buffer; return next uschar */
3924 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
3928 tls_getbuf(unsigned * len)
3933 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
3934 if (!tls_refill(*len))
3936 if (!ssl_xfer_error) return smtp_getbuf(len);
3941 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
3943 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
3944 ssl_xfer_buffer_lwm += size;
3953 #ifndef DISABLE_DKIM
3954 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
3956 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
3962 tls_could_read(void)
3964 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm
3965 || SSL_pending(state_server.lib_state.lib_ssl) > 0;
3969 /*************************************************
3970 * Read bytes from TLS channel *
3971 *************************************************/
3975 ct_ctx client context pointer, or NULL for the one global server context
3979 Returns: the number of bytes read
3980 -1 after a failed read, including EOF
3982 Only used by the client-side TLS.
3986 tls_read(void * ct_ctx, uschar *buff, size_t len)
3988 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
3989 : state_server.lib_state.lib_ssl;
3993 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
3994 buff, (unsigned int)len);
3997 inbytes = SSL_read(ssl, CS buff, len);
3998 error = SSL_get_error(ssl, inbytes);
4000 if (error == SSL_ERROR_ZERO_RETURN)
4002 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
4005 else if (error != SSL_ERROR_NONE)
4015 /*************************************************
4016 * Write bytes down TLS channel *
4017 *************************************************/
4021 ct_ctx client context pointer, or NULL for the one global server context
4024 more further data expected soon
4026 Returns: the number of bytes after a successful write,
4027 -1 after a failed write
4029 Used by both server-side and client-side TLS. Calling with len zero and more unset
4030 will flush buffered writes; buff can be null for this case.
4034 tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
4037 int outbytes, error;
4039 ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
4040 : state_server.lib_state.lib_ssl;
4041 static gstring * server_corked = NULL;
4042 gstring ** corkedp = ct_ctx
4043 ? &((exim_openssl_client_tls_ctx *)ct_ctx)->corked : &server_corked;
4044 gstring * corked = *corkedp;
4046 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
4047 buff, (unsigned long)len, more ? ", more" : "");
4049 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
4050 "more" is notified. This hack is only ok if small amounts are involved AND only
4051 one stream does it, in one context (i.e. no store reset). Currently it is used
4052 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only.
4053 We support callouts done by the server process by using a separate client
4054 context for the stashed information. */
4055 /* + if PIPE_COMMAND, banner & ehlo-resp for smmtp-on-connect. Suspect there's
4056 a store reset there, so use POOL_PERM. */
4057 /* + if CHUNKING, cmds EHLO,MAIL,RCPT(s),BDAT */
4061 if (!len) buff = US &error; /* dummy just so that string_catn is ok */
4063 int save_pool = store_pool;
4064 store_pool = POOL_PERM;
4066 corked = string_catn(corked, buff, len);
4068 store_pool = save_pool;
4075 buff = CUS corked->s;
4080 for (int left = len; left > 0;)
4082 DEBUG(D_tls) debug_printf("SSL_write(%p, %p, %d)\n", ssl, buff, left);
4084 outbytes = SSL_write(ssl, CS buff, left);
4085 error = SSL_get_error(ssl, outbytes);
4086 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
4089 case SSL_ERROR_NONE: /* the usual case */
4095 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4096 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
4099 case SSL_ERROR_ZERO_RETURN:
4100 log_write(0, LOG_MAIN, "SSL channel closed on write");
4103 case SSL_ERROR_SYSCALL:
4104 if (ct_ctx || errno != ECONNRESET || !f.smtp_in_quit)
4105 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
4106 sender_fullhost ? sender_fullhost : US"<unknown>",
4108 else if (LOGGING(protocol_detail))
4109 log_write(0, LOG_MAIN, "[%s] after QUIT, client reset TCP before"
4110 " SMTP response and TLS close\n", sender_host_address);
4112 DEBUG(D_tls) debug_printf("[%s] SSL_write: after QUIT,"
4113 " client reset TCP before TLS close\n", sender_host_address);
4117 log_write(0, LOG_MAIN, "SSL_write error %d", error);
4128 ct_ctx client TLS context pointer, or NULL for the one global server context
4132 tls_shutdown_wr(void * ct_ctx)
4134 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4135 SSL ** sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4136 int * fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4139 if (*fdp < 0) return; /* TLS was not active */
4141 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
4143 HDEBUG(D_transport|D_tls|D_acl|D_v) debug_printf_indent(" SMTP(TLS shutdown)>>\n");
4144 rc = SSL_shutdown(*sslp);
4145 if (rc < 0) DEBUG(D_tls)
4147 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4148 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4152 /*************************************************
4153 * Close down a TLS session *
4154 *************************************************/
4156 /* This is also called from within a delivery subprocess forked from the
4157 daemon, to shut down the TLS library, without actually doing a shutdown (which
4158 would tamper with the SSL session in the parent process).
4161 ct_ctx client TLS context pointer, or NULL for the one global server context
4162 do_shutdown 0 no data-flush or TLS close-alert
4163 1 if TLS close-alert is to be sent,
4164 2 if also response to be waited for
4168 Used by both server-side and client-side TLS.
4172 tls_close(void * ct_ctx, int do_shutdown)
4174 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4175 SSL ** sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4176 int * fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4178 if (*fdp < 0) return; /* TLS was not active */
4183 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
4184 do_shutdown > 1 ? " (with response-wait)" : "");
4186 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
4188 if ( (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
4192 rc = SSL_shutdown(*sslp); /* wait for response */
4196 if (rc < 0) DEBUG(D_tls)
4198 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4199 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4203 if (!o_ctx) /* server side */
4205 #ifndef DISABLE_OCSP
4206 sk_X509_pop_free(state_server.verify_stack, X509_free);
4207 state_server.verify_stack = NULL;
4210 receive_getc = smtp_getc;
4211 receive_getbuf = smtp_getbuf;
4212 receive_get_cache = smtp_get_cache;
4213 receive_ungetc = smtp_ungetc;
4214 receive_feof = smtp_feof;
4215 receive_ferror = smtp_ferror;
4216 receive_smtp_buffered = smtp_buffered;
4217 tls_in.active.tls_ctx = NULL;
4219 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
4230 /*************************************************
4231 * Let tls_require_ciphers be checked at startup *
4232 *************************************************/
4234 /* The tls_require_ciphers option, if set, must be something which the
4237 Returns: NULL on success, or error message
4241 tls_validate_require_cipher(void)
4244 uschar *s, *expciphers, *err;
4248 if (!(tls_require_ciphers && *tls_require_ciphers))
4251 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
4253 return US"failed to expand tls_require_ciphers";
4255 if (!(expciphers && *expciphers))
4258 /* normalisation ripped from above */
4260 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
4264 if (lib_ctx_new(&ctx, NULL, &err) == OK)
4267 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
4269 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
4271 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4272 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
4273 expciphers, ssl_errstring);
4284 /*************************************************
4285 * Report the library versions. *
4286 *************************************************/
4288 /* There have historically been some issues with binary compatibility in
4289 OpenSSL libraries; if Exim (like many other applications) is built against
4290 one version of OpenSSL but the run-time linker picks up another version,
4291 it can result in serious failures, including crashing with a SIGSEGV. So
4292 report the version found by the compiler and the run-time version.
4294 Note: some OS vendors backport security fixes without changing the version
4295 number/string, and the version date remains unchanged. The _build_ date
4296 will change, so we can more usefully assist with version diagnosis by also
4297 reporting the build date.
4299 Arguments: a FILE* to print the results to
4304 tls_version_report(FILE *f)
4306 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
4309 OPENSSL_VERSION_TEXT,
4310 SSLeay_version(SSLEAY_VERSION),
4311 SSLeay_version(SSLEAY_BUILT_ON));
4312 /* third line is 38 characters for the %s and the line is 73 chars long;
4313 the OpenSSL output includes a "built on: " prefix already. */
4319 /*************************************************
4320 * Random number generation *
4321 *************************************************/
4323 /* Pseudo-random number generation. The result is not expected to be
4324 cryptographically strong but not so weak that someone will shoot themselves
4325 in the foot using it as a nonce in input in some email header scheme or
4326 whatever weirdness they'll twist this into. The result should handle fork()
4327 and avoid repeating sequences. OpenSSL handles that for us.
4331 Returns a random number in range [0, max-1]
4335 vaguely_random_number(int max)
4339 static pid_t pidlast = 0;
4341 uschar smallbuf[sizeof(r)];
4347 if (pidnow != pidlast)
4349 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
4350 is unique for each thread", this doesn't apparently apply across processes,
4351 so our own warning from vaguely_random_number_fallback() applies here too.
4352 Fix per PostgreSQL. */
4358 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
4362 gettimeofday(&r.tv, NULL);
4365 RAND_seed(US (&r), sizeof(r));
4367 /* We're after pseudo-random, not random; if we still don't have enough data
4368 in the internal PRNG then our options are limited. We could sleep and hope
4369 for entropy to come along (prayer technique) but if the system is so depleted
4370 in the first place then something is likely to just keep taking it. Instead,
4371 we'll just take whatever little bit of pseudo-random we can still manage to
4374 needed_len = sizeof(r);
4375 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
4376 asked for a number less than 10. */
4377 for (r = max, i = 0; r; ++i)
4383 #ifdef EXIM_HAVE_RAND_PSEUDO
4384 /* We do not care if crypto-strong */
4385 i = RAND_pseudo_bytes(smallbuf, needed_len);
4387 i = RAND_bytes(smallbuf, needed_len);
4393 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
4394 return vaguely_random_number_fallback(max);
4398 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
4401 /* We don't particularly care about weighted results; if someone wants
4402 smooth distribution and cares enough then they should submit a patch then. */
4409 /*************************************************
4410 * OpenSSL option parse *
4411 *************************************************/
4413 /* Parse one option for tls_openssl_options_parse below
4416 name one option name
4417 value place to store a value for it
4418 Returns success or failure in parsing
4424 tls_openssl_one_option_parse(uschar *name, long *value)
4427 int last = exim_openssl_options_size;
4428 while (last > first)
4430 int middle = (first + last)/2;
4431 int c = Ustrcmp(name, exim_openssl_options[middle].name);
4434 *value = exim_openssl_options[middle].value;
4448 /*************************************************
4449 * OpenSSL option parsing logic *
4450 *************************************************/
4452 /* OpenSSL has a number of compatibility options which an administrator might
4453 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
4454 we look like log_selector.
4457 option_spec the administrator-supplied string of options
4458 results ptr to long storage for the options bitmap
4459 Returns success or failure
4463 tls_openssl_options_parse(uschar *option_spec, long *results)
4466 uschar * exp, * end;
4468 BOOL adding, item_parsed;
4470 /* Server: send no (<= TLS1.2) session tickets */
4471 result = SSL_OP_NO_TICKET;
4473 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
4474 from default because it increases BEAST susceptibility. */
4475 #ifdef SSL_OP_NO_SSLv2
4476 result |= SSL_OP_NO_SSLv2;
4478 #ifdef SSL_OP_NO_SSLv3
4479 result |= SSL_OP_NO_SSLv3;
4481 #ifdef SSL_OP_SINGLE_DH_USE
4482 result |= SSL_OP_SINGLE_DH_USE;
4484 #ifdef SSL_OP_NO_RENEGOTIATION
4485 result |= SSL_OP_NO_RENEGOTIATION;
4494 if (!expand_check(option_spec, US"openssl_options", &exp, &end))
4497 for (uschar * s = exp; *s; /**/)
4499 while (isspace(*s)) ++s;
4502 if (*s != '+' && *s != '-')
4504 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
4505 "+ or - expected but found \"%s\"\n", s);
4508 adding = *s++ == '+';
4509 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
4512 item_parsed = tls_openssl_one_option_parse(s, &item);
4516 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
4519 DEBUG(D_tls) debug_printf("openssl option, %s %08lx: %08lx (%s)\n",
4520 adding ? "adding to " : "removing from", result, item, s);
4532 #endif /*!MACRO_PREDEF*/
4535 /* End of tls-openssl.c */