1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2019 */
6 /* Copyright (c) The Exim Maintainers 2020 - 2021 */
7 /* See the file NOTICE for conditions of use and distribution. */
9 /* Portions Copyright (c) The OpenSSL Project 1999 */
11 /* This module provides the TLS (aka SSL) support for Exim using the OpenSSL
12 library. It is #included into the tls.c file when that library is used. The
13 code herein is based on a patch that was originally contributed by Steve
14 Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara.
16 No cryptographic code is included in Exim. All this module does is to call
17 functions from the OpenSSL library. */
22 #include <openssl/lhash.h>
23 #include <openssl/ssl.h>
24 #include <openssl/err.h>
25 #include <openssl/rand.h>
26 #ifndef OPENSSL_NO_ECDH
27 # include <openssl/ec.h>
30 # include <openssl/ocsp.h>
38 # define EXIM_OCSP_SKEW_SECONDS (300L)
39 # define EXIM_OCSP_MAX_AGE (-1L)
42 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
43 # define EXIM_HAVE_OPENSSL_TLSEXT
45 #if OPENSSL_VERSION_NUMBER >= 0x00908000L
46 # define EXIM_HAVE_RSA_GENKEY_EX
48 #if OPENSSL_VERSION_NUMBER >= 0x10100000L
49 # define EXIM_HAVE_OCSP_RESP_COUNT
50 # define OPENSSL_AUTO_SHA256
52 # define EXIM_HAVE_EPHEM_RSA_KEX
53 # define EXIM_HAVE_RAND_PSEUDO
55 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
56 # define EXIM_HAVE_SHA256
59 /* X509_check_host provides sane certificate hostname checking, but was added
60 to OpenSSL late, after other projects forked off the code-base. So in
61 addition to guarding against the base version number, beware that LibreSSL
62 does not (at this time) support this function.
64 If LibreSSL gains a different API, perhaps via libtls, then we'll probably
65 opt to disentangle and ask a LibreSSL user to provide glue for a third
66 crypto provider for libtls instead of continuing to tie the OpenSSL glue
67 into even twistier knots. If LibreSSL gains the same API, we can just
68 change this guard and punt the issue for a while longer. */
70 #ifndef LIBRESSL_VERSION_NUMBER
71 # if OPENSSL_VERSION_NUMBER >= 0x010100000L
72 # define EXIM_HAVE_OPENSSL_CHECKHOST
73 # define EXIM_HAVE_OPENSSL_DH_BITS
74 # define EXIM_HAVE_OPENSSL_TLS_METHOD
75 # define EXIM_HAVE_OPENSSL_KEYLOG
76 # define EXIM_HAVE_OPENSSL_CIPHER_GET_ID
77 # define EXIM_HAVE_SESSION_TICKET
78 # define EXIM_HAVE_OPESSL_TRACE
79 # define EXIM_HAVE_OPESSL_GET0_SERIAL
81 # define EXIM_HAVE_OCSP
83 # define EXIM_HAVE_ALPN /* fail ret from hshake-cb is ignored by LibreSSL */
85 # define EXIM_NEED_OPENSSL_INIT
87 # if OPENSSL_VERSION_NUMBER >= 0x010000000L \
88 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
89 # define EXIM_HAVE_OPENSSL_CHECKHOST
93 #if LIBRESSL_VERSION_NUMBER >= 0x3040000fL
94 # define EXIM_HAVE_OPENSSL_CIPHER_GET_ID
97 #if !defined(LIBRESSL_VERSION_NUMBER) \
98 || LIBRESSL_VERSION_NUMBER >= 0x20010000L
99 # if !defined(OPENSSL_NO_ECDH)
100 # if OPENSSL_VERSION_NUMBER >= 0x0090800fL
101 # define EXIM_HAVE_ECDH
103 # if OPENSSL_VERSION_NUMBER >= 0x10002000L
104 # define EXIM_HAVE_OPENSSL_EC_NIST2NID
109 #ifndef LIBRESSL_VERSION_NUMBER
110 # if OPENSSL_VERSION_NUMBER >= 0x010101000L
111 # define OPENSSL_HAVE_KEYLOG_CB
112 # define OPENSSL_HAVE_NUM_TICKETS
113 # define EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
115 # define OPENSSL_BAD_SRVR_OURCERT
119 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
120 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
121 # define DISABLE_OCSP
124 #ifndef DISABLE_TLS_RESUME
125 # if OPENSSL_VERSION_NUMBER < 0x0101010L
126 # error OpenSSL version too old for session-resumption
130 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
131 # include <openssl/x509v3.h>
134 #ifndef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
135 # ifndef EXIM_HAVE_OPENSSL_CIPHER_GET_ID
136 # define SSL_CIPHER_get_id(c) (c->id)
138 # ifndef MACRO_PREDEF
139 # include "tls-cipher-stdname.c"
143 /*************************************************
144 * OpenSSL option parse *
145 *************************************************/
147 typedef struct exim_openssl_option {
150 } exim_openssl_option;
151 /* We could use a macro to expand, but we need the ifdef and not all the
152 options document which version they were introduced in. Policylet: include
153 all options unless explicitly for DTLS, let the administrator choose which
156 This list is current as of:
159 XXX could we autobuild this list, as with predefined-macros?
160 Seems just parsing ssl.h for SSL_OP_.* would be enough (except to exclude DTLS).
161 Also allow a numeric literal?
163 static exim_openssl_option exim_openssl_options[] = {
164 /* KEEP SORTED ALPHABETICALLY! */
166 { US"all", (long) SSL_OP_ALL },
168 #ifdef SSL_OP_ALLOW_NO_DHE_KEX
169 { US"allow_no_dhe_kex", SSL_OP_ALLOW_NO_DHE_KEX },
171 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
172 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
174 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
175 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
177 #ifdef SSL_OP_CRYPTOPRO_TLSEXT_BUG
178 { US"cryptopro_tlsext_bug", SSL_OP_CRYPTOPRO_TLSEXT_BUG },
180 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
181 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
183 #ifdef SSL_OP_ENABLE_MIDDLEBOX_COMPAT
184 { US"enable_middlebox_compat", SSL_OP_ENABLE_MIDDLEBOX_COMPAT },
186 #ifdef SSL_OP_EPHEMERAL_RSA
187 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
189 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
190 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
192 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
193 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
195 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
196 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
198 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
199 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
201 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
202 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
204 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
205 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
207 #ifdef SSL_OP_NO_ANTI_REPLAY
208 { US"no_anti_replay", SSL_OP_NO_ANTI_REPLAY },
210 #ifdef SSL_OP_NO_COMPRESSION
211 { US"no_compression", SSL_OP_NO_COMPRESSION },
213 #ifdef SSL_OP_NO_ENCRYPT_THEN_MAC
214 { US"no_encrypt_then_mac", SSL_OP_NO_ENCRYPT_THEN_MAC },
216 #ifdef SSL_OP_NO_RENEGOTIATION
217 { US"no_renegotiation", SSL_OP_NO_RENEGOTIATION },
219 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
220 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
222 #ifdef SSL_OP_NO_SSLv2
223 { US"no_sslv2", SSL_OP_NO_SSLv2 },
225 #ifdef SSL_OP_NO_SSLv3
226 { US"no_sslv3", SSL_OP_NO_SSLv3 },
228 #ifdef SSL_OP_NO_TICKET
229 { US"no_ticket", SSL_OP_NO_TICKET },
231 #ifdef SSL_OP_NO_TLSv1
232 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
234 #ifdef SSL_OP_NO_TLSv1_1
235 # if OPENSSL_VERSION_NUMBER < 0x30000000L
236 # if SSL_OP_NO_TLSv1_1 == 0x00000400L
237 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
238 # warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
239 # define NO_SSL_OP_NO_TLSv1_1
242 # ifndef NO_SSL_OP_NO_TLSv1_1
243 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
246 #ifdef SSL_OP_NO_TLSv1_2
247 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
249 #ifdef SSL_OP_NO_TLSv1_3
250 { US"no_tlsv1_3", SSL_OP_NO_TLSv1_3 },
252 #ifdef SSL_OP_PRIORITIZE_CHACHA
253 { US"prioritize_chacha", SSL_OP_PRIORITIZE_CHACHA },
255 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
256 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
258 #ifdef SSL_OP_SINGLE_DH_USE
259 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
261 #ifdef SSL_OP_SINGLE_ECDH_USE
262 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
264 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
265 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
267 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
268 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
270 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
271 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
273 #ifdef SSL_OP_TLS_D5_BUG
274 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
276 #ifdef SSL_OP_TLS_ROLLBACK_BUG
277 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
279 #ifdef SSL_OP_TLSEXT_PADDING
280 { US"tlsext_padding", SSL_OP_TLSEXT_PADDING },
285 static int exim_openssl_options_size = nelem(exim_openssl_options);
286 static long init_options = 0;
295 for (struct exim_openssl_option * o = exim_openssl_options;
296 o < exim_openssl_options + nelem(exim_openssl_options); o++)
298 /* Trailing X is workaround for problem with _OPT_OPENSSL_NO_TLSV1
299 being a ".ifdef _OPT_OPENSSL_NO_TLSV1_3" match */
301 spf(buf, sizeof(buf), US"_OPT_OPENSSL_%T_X", o->name);
302 builtin_macro_create(buf);
305 # ifndef DISABLE_TLS_RESUME
306 builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING );
308 # ifdef SSL_OP_NO_TLSv1_3
309 builtin_macro_create(US"_HAVE_TLS1_3");
311 # ifdef OPENSSL_BAD_SRVR_OURCERT
312 builtin_macro_create(US"_TLS_BAD_MULTICERT_IN_OURCERT");
314 # ifdef EXIM_HAVE_OCSP
315 builtin_macro_create(US"_HAVE_TLS_OCSP");
316 builtin_macro_create(US"_HAVE_TLS_OCSP_LIST");
318 # ifdef EXIM_HAVE_ALPN
319 builtin_macro_create(US"_HAVE_TLS_ALPN");
324 /******************************************************************************/
326 /* Structure for collecting random data for seeding. */
328 typedef struct randstuff {
333 /* Local static variables */
335 static BOOL client_verify_callback_called = FALSE;
336 static BOOL server_verify_callback_called = FALSE;
337 static const uschar *sid_ctx = US"exim";
339 /* We have three different contexts to care about.
341 Simple case: client, `client_ctx`
342 As a client, we can be doing a callout or cut-through delivery while receiving
343 a message. So we have a client context, which should have options initialised
344 from the SMTP Transport. We may also concurrently want to make TLS connections
345 to utility daemons, so client-contexts are allocated and passed around in call
346 args rather than using a gobal.
349 There are two cases: with and without ServerNameIndication from the client.
350 Given TLS SNI, we can be using different keys, certs and various other
351 configuration settings, because they're re-expanded with $tls_sni set. This
352 allows vhosting with TLS. This SNI is sent in the handshake.
353 A client might not send SNI, so we need a fallback, and an initial setup too.
354 So as a server, we start out using `server_ctx`.
355 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
356 `server_sni` from `server_ctx` and then initialise settings by re-expanding
364 } exim_openssl_client_tls_ctx;
367 /* static SSL_CTX *server_ctx = NULL; */
368 /* static SSL *server_ssl = NULL; */
370 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
371 static SSL_CTX *server_sni = NULL;
373 #ifdef EXIM_HAVE_ALPN
374 static BOOL server_seen_alpn = FALSE;
377 static char ssl_errstring[256];
379 static int ssl_session_timeout = 7200; /* Two hours */
380 static BOOL client_verify_optional = FALSE;
381 static BOOL server_verify_optional = FALSE;
383 static BOOL reexpand_tls_files_for_sni = FALSE;
386 typedef struct ocsp_resp {
387 struct ocsp_resp * next;
388 OCSP_RESPONSE * resp;
391 typedef struct exim_openssl_state {
392 exim_tlslib_state lib_state;
393 #define lib_ctx libdata0
394 #define lib_ssl libdata1
397 uschar * certificate;
401 STACK_OF(X509) *verify_stack; /* chain for verifying the proof */
405 const uschar *file_expanded;
406 ocsp_resplist *olist;
409 X509_STORE *verify_store; /* non-null if status requested */
410 BOOL verify_required;
415 /* these are cached from first expand */
416 uschar * server_cipher_list;
417 /* only passed down to tls_error: */
419 const uschar * verify_cert_hostnames;
420 #ifndef DISABLE_EVENT
421 uschar * event_action;
423 } exim_openssl_state_st;
425 /* should figure out a cleanup of API to handle state preserved per
426 implementation, for various reasons, which can be void * in the APIs.
427 For now, we hack around it. */
428 exim_openssl_state_st *client_static_state = NULL; /*XXX should not use static; multiple concurrent clients! */
429 exim_openssl_state_st state_server = {.is_server = TRUE};
432 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host,
437 static int tls_server_stapling_cb(SSL *s, void *arg);
442 /* Daemon-called, before every connection, key create/rotate */
443 #ifndef DISABLE_TLS_RESUME
444 static void tk_init(void);
445 static int tls_exdata_idx = -1;
449 tls_per_lib_daemon_tick(void)
451 #ifndef DISABLE_TLS_RESUME
456 /* Called once at daemon startup */
459 tls_per_lib_daemon_init(void)
461 tls_daemon_creds_reload();
465 /*************************************************
467 *************************************************/
469 /* Called from lots of places when errors occur before actually starting to do
470 the TLS handshake, that is, while the session is still in clear. Always returns
471 DEFER for a server and FAIL for a client so that most calls can use "return
472 tls_error(...)" to do this processing and then give an appropriate return. A
473 single function is used for both server and client, because it is called from
474 some shared functions.
477 prefix text to include in the logged error
478 host NULL if setting up a server;
479 the connected host if setting up a client
480 msg error message or NULL if we should ask OpenSSL
481 errstr pointer to output error message
483 Returns: OK/DEFER/FAIL
487 tls_error(uschar * prefix, const host_item * host, uschar * msg, uschar ** errstr)
491 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
492 msg = US ssl_errstring;
495 msg = string_sprintf("(%s): %s", prefix, msg);
496 DEBUG(D_tls) debug_printf("TLS error '%s'\n", msg);
497 if (errstr) *errstr = msg;
498 return host ? FAIL : DEFER;
503 /**************************************************
504 * General library initalisation *
505 **************************************************/
508 lib_rand_init(void * addr)
511 if (!RAND_status()) return TRUE;
513 gettimeofday(&r.tv, NULL);
515 RAND_seed(US (&r), sizeof(r));
516 RAND_seed(US big_buffer, big_buffer_size);
517 if (addr) RAND_seed(US addr, sizeof(addr));
519 return RAND_status();
524 tls_openssl_init(void)
526 static BOOL once = FALSE;
530 #ifdef EXIM_NEED_OPENSSL_INIT
531 SSL_load_error_strings(); /* basic set up */
532 OpenSSL_add_ssl_algorithms();
535 #if defined(EXIM_HAVE_SHA256) && !defined(OPENSSL_AUTO_SHA256)
536 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
537 list of available digests. */
538 EVP_add_digest(EVP_sha256());
541 (void) lib_rand_init(NULL);
542 (void) tls_openssl_options_parse(openssl_options, &init_options);
547 /*************************************************
548 * Initialize for DH *
549 *************************************************/
551 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
554 sctx The current SSL CTX (inbound or outbound)
555 dhparam DH parameter file or fixed parameter identity string
556 host connected host, if client; NULL if server
557 errstr error string pointer
559 Returns: TRUE if OK (nothing to set up, or setup worked)
563 init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host, uschar ** errstr)
571 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded, errstr))
574 if (!dhexpanded || !*dhexpanded)
575 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
576 else if (dhexpanded[0] == '/')
578 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
580 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
581 host, US strerror(errno), errstr);
587 if (Ustrcmp(dhexpanded, "none") == 0)
589 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
593 if (!(pem = std_dh_prime_named(dhexpanded)))
595 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
596 host, US strerror(errno), errstr);
599 bio = BIO_new_mem_buf(CS pem, -1);
602 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
605 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
610 /* note: our default limit of 2236 is not a multiple of 8; the limit comes from
611 * an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with
612 * 2236. But older OpenSSL can only report in bytes (octets), not bits.
613 * If someone wants to dance at the edge, then they can raise the limit or use
614 * current libraries. */
615 #ifdef EXIM_HAVE_OPENSSL_DH_BITS
616 /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022
617 * This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */
618 dh_bitsize = DH_bits(dh);
620 dh_bitsize = 8 * DH_size(dh);
623 /* Even if it is larger, we silently return success rather than cause things
624 * to fail out, so that a too-large DH will not knock out all TLS; it's a
625 * debatable choice. */
626 if (dh_bitsize > tls_dh_max_bits)
629 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d\n",
630 dh_bitsize, tls_dh_max_bits);
634 SSL_CTX_set_tmp_dh(sctx, dh);
636 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
637 dhexpanded ? dhexpanded : US"default", dh_bitsize);
649 /*************************************************
650 * Initialize for ECDH *
651 *************************************************/
653 /* Load parameters for ECDH encryption.
655 For now, we stick to NIST P-256 because: it's simple and easy to configure;
656 it avoids any patent issues that might bite redistributors; despite events in
657 the news and concerns over curve choices, we're not cryptographers, we're not
658 pretending to be, and this is "good enough" to be better than no support,
659 protecting against most adversaries. Given another year or two, there might
660 be sufficient clarity about a "right" way forward to let us make an informed
661 decision, instead of a knee-jerk reaction.
663 Longer-term, we should look at supporting both various named curves and
664 external files generated with "openssl ecparam", much as we do for init_dh().
665 We should also support "none" as a value, to explicitly avoid initialisation.
670 sctx The current SSL CTX (inbound or outbound)
671 host connected host, if client; NULL if server
672 errstr error string pointer
674 Returns: TRUE if OK (nothing to set up, or setup worked)
678 init_ecdh(SSL_CTX * sctx, host_item * host, uschar ** errstr)
680 #ifdef OPENSSL_NO_ECDH
688 if (host) /* No ECDH setup for clients, only for servers */
691 # ifndef EXIM_HAVE_ECDH
693 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
697 if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve, errstr))
699 if (!exp_curve || !*exp_curve)
702 /* "auto" needs to be handled carefully.
703 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
704 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
705 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
706 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
707 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
709 if (Ustrcmp(exp_curve, "auto") == 0)
711 #if OPENSSL_VERSION_NUMBER < 0x10002000L
712 DEBUG(D_tls) debug_printf(
713 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
714 exp_curve = US"prime256v1";
716 # if defined SSL_CTRL_SET_ECDH_AUTO
717 DEBUG(D_tls) debug_printf(
718 "ECDH OpenSSL 1.0.2+: temp key parameter settings: autoselection\n");
719 SSL_CTX_set_ecdh_auto(sctx, 1);
722 DEBUG(D_tls) debug_printf(
723 "ECDH OpenSSL 1.1.0+: temp key parameter settings: default selection\n");
729 DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve);
730 if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef
731 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
732 && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef
736 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve),
741 # if OPENSSL_VERSION_NUMBER < 0x30000000L
744 if (!(ecdh = EC_KEY_new_by_curve_name(nid)))
746 tls_error(US"Unable to create ec curve", host, NULL, errstr);
750 /* The "tmp" in the name here refers to setting a temporary key
751 not to the stability of the interface. */
753 if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0))
754 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), host, NULL, errstr);
756 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve);
760 #else /* v 3.0.0 + */
762 if ((rv = SSL_CTX_set1_groups(sctx, &nid, 1)) == 0)
763 tls_error(string_sprintf("Error enabling '%s' group", exp_curve), host, NULL, errstr);
765 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' group\n", exp_curve);
771 # endif /*EXIM_HAVE_ECDH*/
772 #endif /*OPENSSL_NO_ECDH*/
777 /*************************************************
778 * Expand key and cert file specs *
779 *************************************************/
783 s SSL connection (not used)
787 Returns: pointer to generated key
791 rsa_callback(SSL *s, int export, int keylength)
794 #ifdef EXIM_HAVE_RSA_GENKEY_EX
795 BIGNUM *bn = BN_new();
798 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
800 #ifdef EXIM_HAVE_RSA_GENKEY_EX
801 if ( !BN_set_word(bn, (unsigned long)RSA_F4)
802 || !(rsa_key = RSA_new())
803 || !RSA_generate_key_ex(rsa_key, keylength, bn, NULL)
806 if (!(rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL)))
810 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
811 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
820 /* Create and install a selfsigned certificate, for use in server mode */
821 /*XXX we could arrange to call this during prelo for a null tls_certificate option.
822 The normal cache inval + relo will suffice.
823 Just need a timer for inval. */
826 tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr)
834 DEBUG(D_tls) debug_printf("TLS: generating selfsigned server cert\n");
835 where = US"allocating pkey";
836 if (!(pkey = EVP_PKEY_new()))
839 where = US"allocating cert";
840 if (!(x509 = X509_new()))
843 where = US"generating pkey";
844 if (!(rsa = rsa_callback(NULL, 0, 2048)))
847 where = US"assigning pkey";
848 if (!EVP_PKEY_assign_RSA(pkey, rsa))
851 X509_set_version(x509, 2); /* N+1 - version 3 */
852 ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
853 X509_gmtime_adj(X509_get_notBefore(x509), 0);
854 X509_gmtime_adj(X509_get_notAfter(x509), (long)2 * 60 * 60); /* 2 hour */
855 X509_set_pubkey(x509, pkey);
857 name = X509_get_subject_name(x509);
858 X509_NAME_add_entry_by_txt(name, "C",
859 MBSTRING_ASC, CUS "UK", -1, -1, 0);
860 X509_NAME_add_entry_by_txt(name, "O",
861 MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0);
862 X509_NAME_add_entry_by_txt(name, "CN",
863 MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0);
864 X509_set_issuer_name(x509, name);
866 where = US"signing cert";
867 if (!X509_sign(x509, pkey, EVP_md5()))
870 where = US"installing selfsign cert";
871 if (!SSL_CTX_use_certificate(sctx, x509))
874 where = US"installing selfsign key";
875 if (!SSL_CTX_use_PrivateKey(sctx, pkey))
881 (void) tls_error(where, NULL, NULL, errstr);
882 if (x509) X509_free(x509);
883 if (pkey) EVP_PKEY_free(pkey);
893 /*************************************************
894 * Information callback *
895 *************************************************/
897 /* The SSL library functions call this from time to time to indicate what they
898 are doing. We copy the string to the debugging output when TLS debugging has
910 info_callback(SSL *s, int where, int ret)
916 if (where & SSL_ST_CONNECT)
917 str = US"SSL_connect";
918 else if (where & SSL_ST_ACCEPT)
919 str = US"SSL_accept";
921 str = US"SSL info (undefined)";
923 if (where & SSL_CB_LOOP)
924 debug_printf("%s: %s\n", str, SSL_state_string_long(s));
925 else if (where & SSL_CB_ALERT)
926 debug_printf("SSL3 alert %s:%s:%s\n",
927 str = where & SSL_CB_READ ? US"read" : US"write",
928 SSL_alert_type_string_long(ret), SSL_alert_desc_string_long(ret));
929 else if (where & SSL_CB_EXIT)
932 debug_printf("%s: failed in %s\n", str, SSL_state_string_long(s));
934 debug_printf("%s: error in %s\n", str, SSL_state_string_long(s));
936 else if (where & SSL_CB_HANDSHAKE_START)
937 debug_printf("%s: hshake start: %s\n", str, SSL_state_string_long(s));
938 else if (where & SSL_CB_HANDSHAKE_DONE)
939 debug_printf("%s: hshake done: %s\n", str, SSL_state_string_long(s));
943 #ifdef OPENSSL_HAVE_KEYLOG_CB
945 keylog_callback(const SSL *ssl, const char *line)
949 DEBUG(D_tls) debug_printf("%.200s\n", line);
950 if (!(filename = getenv("SSLKEYLOGFILE"))) return;
951 if (!(fp = fopen(filename, "a"))) return;
952 fprintf(fp, "%s\n", line);
961 #ifndef DISABLE_EVENT
963 verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
964 BOOL *calledp, const BOOL *optionalp, const uschar * what)
970 ev = tlsp == &tls_out ? client_static_state->event_action : event_action;
973 DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth);
974 old_cert = tlsp->peercert;
975 tlsp->peercert = X509_dup(cert);
976 /* NB we do not bother setting peerdn */
977 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
979 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
980 "depth=%d cert=%s: %s",
981 tlsp == &tls_out ? deliver_host_address : sender_host_address,
982 what, depth, dn, yield);
986 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
987 return 1; /* reject (leaving peercert set) */
989 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
990 "(host in tls_try_verify_hosts)\n");
991 tlsp->verify_override = TRUE;
993 X509_free(tlsp->peercert);
994 tlsp->peercert = old_cert;
1000 /*************************************************
1001 * Callback for verification *
1002 *************************************************/
1004 /* The SSL library does certificate verification if set up to do so. This
1005 callback has the current yes/no state is in "state". If verification succeeded,
1006 we set the certificate-verified flag. If verification failed, what happens
1007 depends on whether the client is required to present a verifiable certificate
1010 If verification is optional, we change the state to yes, but still log the
1011 verification error. For some reason (it really would help to have proper
1012 documentation of OpenSSL), this callback function then gets called again, this
1013 time with state = 1. We must take care not to set the private verified flag on
1014 the second time through.
1016 Note: this function is not called if the client fails to present a certificate
1017 when asked. We get here only if a certificate has been received. Handling of
1018 optional verification for this case is done when requesting SSL to verify, by
1019 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
1021 May be called multiple times for different issues with a certificate, even
1022 for a given "depth" in the certificate chain.
1025 preverify_ok current yes/no state as 1/0
1026 x509ctx certificate information.
1027 tlsp per-direction (client vs. server) support data
1028 calledp has-been-called flag
1029 optionalp verification-is-optional flag
1031 Returns: 0 if verification should fail, otherwise 1
1035 verify_callback(int preverify_ok, X509_STORE_CTX * x509ctx,
1036 tls_support * tlsp, BOOL * calledp, BOOL * optionalp)
1038 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
1039 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
1042 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
1044 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
1045 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1046 tlsp == &tls_out ? deliver_host_address : sender_host_address);
1049 dn[sizeof(dn)-1] = '\0';
1051 tlsp->verify_override = FALSE;
1052 if (preverify_ok == 0)
1054 uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])",
1055 *verify_mode, sender_host_address)
1057 log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
1058 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1060 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn);
1064 if (!tlsp->peercert)
1065 tlsp->peercert = X509_dup(cert); /* record failing cert */
1066 return 0; /* reject */
1068 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
1069 "tls_try_verify_hosts)\n");
1070 tlsp->verify_override = TRUE;
1073 else if (depth != 0)
1075 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
1076 #ifndef DISABLE_OCSP
1077 if (tlsp == &tls_out && client_static_state->u_ocsp.client.verify_store)
1078 { /* client, wanting stapling */
1079 /* Add the server cert's signing chain as the one
1080 for the verification of the OCSP stapled information. */
1082 if (!X509_STORE_add_cert(client_static_state->u_ocsp.client.verify_store,
1085 sk_X509_push(client_static_state->verify_stack, cert);
1088 #ifndef DISABLE_EVENT
1089 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
1090 return 0; /* reject, with peercert set */
1095 const uschar * verify_cert_hostnames;
1097 if ( tlsp == &tls_out
1098 && ((verify_cert_hostnames = client_static_state->verify_cert_hostnames)))
1099 /* client, wanting hostname check */
1102 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
1103 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
1104 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
1106 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
1107 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
1110 const uschar * list = verify_cert_hostnames;
1113 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
1114 if ((rc = X509_check_host(cert, CCS name, 0,
1115 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
1116 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
1121 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1122 tlsp == &tls_out ? deliver_host_address : sender_host_address);
1129 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
1132 uschar * extra = verify_mode
1133 ? string_sprintf(" (during %c-verify for [%s])",
1134 *verify_mode, sender_host_address)
1136 log_write(0, LOG_MAIN,
1137 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
1138 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1139 extra, dn, verify_cert_hostnames);
1143 if (!tlsp->peercert)
1144 tlsp->peercert = X509_dup(cert); /* record failing cert */
1145 return 0; /* reject */
1147 DEBUG(D_tls) debug_printf("SSL verify name failure overridden (host in "
1148 "tls_try_verify_hosts)\n");
1149 tlsp->verify_override = TRUE;
1153 #ifndef DISABLE_EVENT
1154 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
1155 return 0; /* reject, with peercert set */
1158 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
1159 *calledp ? "" : " authenticated", dn);
1163 return 1; /* accept, at least for this level */
1167 verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
1169 return verify_callback(preverify_ok, x509ctx, &tls_out,
1170 &client_verify_callback_called, &client_verify_optional);
1174 verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
1176 return verify_callback(preverify_ok, x509ctx, &tls_in,
1177 &server_verify_callback_called, &server_verify_optional);
1183 /* This gets called *by* the dane library verify callback, which interposes
1187 verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
1189 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
1191 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
1192 #ifndef DISABLE_EVENT
1193 BOOL dummy_called, optional = FALSE;
1196 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
1198 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
1199 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1200 deliver_host_address);
1203 dn[sizeof(dn)-1] = '\0';
1205 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
1206 preverify_ok ? "ok":"BAD", depth, dn);
1208 #ifndef DISABLE_EVENT
1209 if (verify_event(&tls_out, cert, depth, dn,
1210 &dummy_called, &optional, US"DANE"))
1211 return 0; /* reject, with peercert set */
1214 if (preverify_ok == 1)
1216 tls_out.dane_verified = TRUE;
1217 #ifndef DISABLE_OCSP
1218 if (client_static_state->u_ocsp.client.verify_store)
1219 { /* client, wanting stapling */
1220 /* Add the server cert's signing chain as the one
1221 for the verification of the OCSP stapled information. */
1223 if (!X509_STORE_add_cert(client_static_state->u_ocsp.client.verify_store,
1226 sk_X509_push(client_static_state->verify_stack, cert);
1232 int err = X509_STORE_CTX_get_error(x509ctx);
1234 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
1235 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
1238 return preverify_ok;
1241 #endif /*SUPPORT_DANE*/
1244 #ifndef DISABLE_OCSP
1245 /*************************************************
1246 * Load OCSP information into state *
1247 *************************************************/
1248 /* Called to load the server OCSP response from the given file into memory, once
1249 caller has determined this is needed. Checks validity. Debugs a message
1252 ASSUMES: single response, for single cert.
1255 state various parts of session state
1256 filename the filename putatively holding an OCSP response
1257 is_pem file is PEM format; otherwise is DER
1261 ocsp_load_response(exim_openssl_state_st * state, const uschar * filename,
1265 OCSP_RESPONSE * resp;
1266 OCSP_BASICRESP * basic_response;
1267 OCSP_SINGLERESP * single_response;
1268 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
1269 STACK_OF(X509) * sk;
1270 unsigned long verify_flags;
1271 int status, reason, i;
1274 debug_printf("tls_ocsp_file (%s) '%s'\n", is_pem ? "PEM" : "DER", filename);
1276 if (!filename || !*filename) return;
1279 if (!(bio = BIO_new_file(CS filename, "rb")))
1281 log_write(0, LOG_MAIN|LOG_PANIC,
1282 "Failed to open OCSP response file \"%s\": %.100s",
1283 filename, ERR_reason_error_string(ERR_get_error()));
1289 uschar * data, * freep;
1292 if (!PEM_read_bio(bio, &dummy, &dummy, &data, &len))
1294 log_write(0, LOG_MAIN|LOG_PANIC, "Failed to read PEM file \"%s\": %.100s",
1295 filename, ERR_reason_error_string(ERR_get_error()));
1299 resp = d2i_OCSP_RESPONSE(NULL, CUSS &data, len);
1300 OPENSSL_free(freep);
1303 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
1308 log_write(0, LOG_MAIN|LOG_PANIC, "Error reading OCSP response from \"%s\": %s",
1309 filename, ERR_reason_error_string(ERR_get_error()));
1313 if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
1315 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
1316 OCSP_response_status_str(status), status);
1322 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1323 OCSP_RESPONSE_print(bp, resp, 0); /* extreme debug: stapling content */
1328 if (!(basic_response = OCSP_response_get1_basic(resp)))
1331 debug_printf("OCSP response parse error: unable to extract basic response.\n");
1335 sk = state->verify_stack;
1336 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
1338 /* May need to expose ability to adjust those flags?
1339 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
1340 OCSP_TRUSTOTHER OCSP_NOINTERN */
1342 /* This does a full verify on the OCSP proof before we load it for serving
1343 up; possibly overkill - just date-checks might be nice enough.
1345 OCSP_basic_verify takes a "store" arg, but does not
1346 use it for the chain verification, which is all we do
1347 when OCSP_NOVERIFY is set. The content from the wire
1348 "basic_response" and a cert-stack "sk" are all that is used.
1350 We have a stack, loaded in setup_certs() if tls_verify_certificates
1351 was a file (not a directory, or "system"). It is unfortunate we
1352 cannot used the connection context store, as that would neatly
1353 handle the "system" case too, but there seems to be no library
1354 function for getting a stack from a store.
1355 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
1356 We do not free the stack since it could be needed a second time for
1359 Separately we might try to replace using OCSP_basic_verify() - which seems to not
1360 be a public interface into the OpenSSL library (there's no manual entry) -
1361 But what with? We also use OCSP_basic_verify in the client stapling callback.
1362 And there we NEED it; we must verify that status... unless the
1363 library does it for us anyway? */
1365 if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0)
1369 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1370 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
1375 /* Here's the simplifying assumption: there's only one response, for the
1376 one certificate we use, and nothing for anything else in a chain. If this
1377 proves false, we need to extract a cert id from our issued cert
1378 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
1379 right cert in the stack and then calls OCSP_single_get0_status()).
1381 I'm hoping to avoid reworking a bunch more of how we handle state here.
1383 XXX that will change when we add support for (TLS1.3) whole-chain stapling
1386 if (!(single_response = OCSP_resp_get0(basic_response, 0)))
1389 debug_printf("Unable to get first response from OCSP basic response.\n");
1393 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
1394 if (status != V_OCSP_CERTSTATUS_GOOD)
1396 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
1397 OCSP_cert_status_str(status), status,
1398 OCSP_crl_reason_str(reason), reason);
1402 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1404 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
1409 /* Add the resp to the list used by tls_server_stapling_cb() */
1411 ocsp_resplist ** op = &state->u_ocsp.server.olist, * oentry;
1412 while (oentry = *op)
1414 *op = oentry = store_get(sizeof(ocsp_resplist), FALSE);
1415 oentry->next = NULL;
1416 oentry->resp = resp;
1421 if (f.running_in_test_harness)
1423 extern char ** environ;
1424 if (environ) for (uschar ** p = USS environ; *p; p++)
1425 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1427 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
1428 goto supply_response;
1436 ocsp_free_response_list(exim_openssl_state_st * cbinfo)
1438 for (ocsp_resplist * olist = cbinfo->u_ocsp.server.olist; olist;
1439 olist = olist->next)
1440 OCSP_RESPONSE_free(olist->resp);
1441 cbinfo->u_ocsp.server.olist = NULL;
1443 #endif /*!DISABLE_OCSP*/
1450 tls_add_certfile(SSL_CTX * sctx, exim_openssl_state_st * cbinfo, uschar * file,
1453 DEBUG(D_tls) debug_printf("tls_certificate file '%s'\n", file);
1454 if (!SSL_CTX_use_certificate_chain_file(sctx, CS file))
1455 return tls_error(string_sprintf(
1456 "SSL_CTX_use_certificate_chain_file file=%s", file),
1457 cbinfo->host, NULL, errstr);
1462 tls_add_pkeyfile(SSL_CTX * sctx, exim_openssl_state_st * cbinfo, uschar * file,
1465 DEBUG(D_tls) debug_printf("tls_privatekey file '%s'\n", file);
1466 if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM))
1467 return tls_error(string_sprintf(
1468 "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr);
1475 /* Called once during tls_init and possibly again during TLS setup, for a
1476 new context, if Server Name Indication was used and tls_sni was seen in
1477 the certificate string.
1480 sctx the SSL_CTX* to update
1481 state various parts of session state
1482 errstr error string pointer
1484 Returns: OK/DEFER/FAIL
1488 tls_expand_session_files(SSL_CTX * sctx, exim_openssl_state_st * state,
1493 if (!state->certificate)
1495 if (!state->is_server) /* client */
1498 if (tls_install_selfsign(sctx, errstr) != OK)
1505 if ( !reexpand_tls_files_for_sni
1506 && ( Ustrstr(state->certificate, US"tls_sni")
1507 || Ustrstr(state->certificate, US"tls_in_sni")
1508 || Ustrstr(state->certificate, US"tls_out_sni")
1510 reexpand_tls_files_for_sni = TRUE;
1512 if (!expand_check(state->certificate, US"tls_certificate", &expanded, errstr))
1516 if (state->is_server)
1518 const uschar * file_list = expanded;
1521 #ifndef DISABLE_OCSP
1522 const uschar * olist = state->u_ocsp.server.file;
1525 BOOL fmt_pem = FALSE;
1528 if (!expand_check(olist, US"tls_ocsp_file", USS &olist, errstr))
1530 if (olist && !*olist)
1533 if ( state->u_ocsp.server.file_expanded && olist
1534 && (Ustrcmp(olist, state->u_ocsp.server.file_expanded) == 0))
1536 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
1541 ocsp_free_response_list(state);
1542 state->u_ocsp.server.file_expanded = olist;
1546 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1548 if ((err = tls_add_certfile(sctx, state, file, errstr)))
1551 #ifndef DISABLE_OCSP
1553 if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1555 if (Ustrncmp(ofile, US"PEM ", 4) == 0)
1560 else if (Ustrncmp(ofile, US"DER ", 4) == 0)
1565 ocsp_load_response(state, ofile, fmt_pem);
1568 DEBUG(D_tls) debug_printf("ran out of ocsp file list\n");
1572 else /* would there ever be a need for multiple client certs? */
1573 if ((err = tls_add_certfile(sctx, state, expanded, errstr)))
1576 if ( state->privatekey
1577 && !expand_check(state->privatekey, US"tls_privatekey", &expanded, errstr))
1580 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1581 of the expansion is an empty string, ignore it also, and assume the private
1582 key is in the same file as the certificate. */
1584 if (expanded && *expanded)
1585 if (state->is_server)
1587 const uschar * file_list = expanded;
1591 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1592 if ((err = tls_add_pkeyfile(sctx, state, file, errstr)))
1595 else /* would there ever be a need for multiple client certs? */
1596 if ((err = tls_add_pkeyfile(sctx, state, expanded, errstr)))
1606 /**************************************************
1607 * One-time init credentials for server and client *
1608 **************************************************/
1611 server_load_ciphers(SSL_CTX * ctx, exim_openssl_state_st * state,
1612 uschar * ciphers, uschar ** errstr)
1614 for (uschar * s = ciphers; *s; s++ ) if (*s == '_') *s = '-';
1615 DEBUG(D_tls) debug_printf("required ciphers: %s\n", ciphers);
1616 if (!SSL_CTX_set_cipher_list(ctx, CS ciphers))
1617 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
1618 state->server_cipher_list = ciphers;
1625 lib_ctx_new(SSL_CTX ** ctxp, host_item * host, uschar ** errstr)
1628 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1629 if (!(ctx = SSL_CTX_new(host ? TLS_client_method() : TLS_server_method())))
1631 if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
1633 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
1635 /* Set up the information callback, which outputs if debugging is at a suitable
1640 SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
1641 #if defined(EXIM_HAVE_OPESSL_TRACE) && !defined(OPENSSL_NO_SSL_TRACE)
1642 /* this needs a debug build of OpenSSL */
1643 SSL_CTX_set_msg_callback(ctx, (void (*)())SSL_trace);
1645 #ifdef OPENSSL_HAVE_KEYLOG_CB
1646 SSL_CTX_set_keylog_callback(ctx, (void (*)())keylog_callback);
1650 /* Automatically re-try reads/writes after renegotiation. */
1651 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
1658 tls_server_creds_init(void)
1661 uschar * dummy_errstr;
1662 unsigned lifetime = 0;
1666 state_server.lib_state = null_tls_preload;
1668 if (lib_ctx_new(&ctx, NULL, &dummy_errstr) != OK)
1670 state_server.lib_state.lib_ctx = ctx;
1672 /* Preload DH params and EC curve */
1674 if (opt_unset_or_noexpand(tls_dhparam))
1676 DEBUG(D_tls) debug_printf("TLS: preloading DH params for server\n");
1677 if (init_dh(ctx, tls_dhparam, NULL, &dummy_errstr))
1678 state_server.lib_state.dh = TRUE;
1680 if (opt_unset_or_noexpand(tls_eccurve))
1682 DEBUG(D_tls) debug_printf("TLS: preloading ECDH curve for server\n");
1683 if (init_ecdh(ctx, NULL, &dummy_errstr))
1684 state_server.lib_state.ecdh = TRUE;
1687 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1688 /* If we can, preload the server-side cert, key and ocsp */
1690 if ( opt_set_and_noexpand(tls_certificate)
1691 # ifndef DISABLE_OCSP
1692 && opt_unset_or_noexpand(tls_ocsp_file)
1694 && opt_unset_or_noexpand(tls_privatekey))
1696 /* Set watches on the filenames. The implementation does de-duplication
1697 so we can just blindly do them all. */
1699 if ( tls_set_watch(tls_certificate, TRUE)
1700 # ifndef DISABLE_OCSP
1701 && tls_set_watch(tls_ocsp_file, TRUE)
1703 && tls_set_watch(tls_privatekey, TRUE))
1705 state_server.certificate = tls_certificate;
1706 state_server.privatekey = tls_privatekey;
1707 #ifndef DISABLE_OCSP
1708 state_server.u_ocsp.server.file = tls_ocsp_file;
1711 DEBUG(D_tls) debug_printf("TLS: preloading server certs\n");
1712 if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
1713 state_server.lib_state.conn_certs = TRUE;
1716 else if ( !tls_certificate && !tls_privatekey
1717 # ifndef DISABLE_OCSP
1721 { /* Generate & preload a selfsigned cert. No files to watch. */
1722 if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
1724 state_server.lib_state.conn_certs = TRUE;
1725 lifetime = f.running_in_test_harness ? 2 : 60 * 60; /* 1 hour */
1729 DEBUG(D_tls) debug_printf("TLS: not preloading server certs\n");
1732 /* If we can, preload the Authorities for checking client certs against.
1733 Actual choice to do verify is made (tls_{,try_}verify_hosts)
1734 at TLS conn startup */
1736 if ( opt_set_and_noexpand(tls_verify_certificates)
1737 && opt_unset_or_noexpand(tls_crl))
1739 /* Watch the default dir also as they are always included */
1741 if ( tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
1742 && tls_set_watch(tls_verify_certificates, FALSE)
1743 && tls_set_watch(tls_crl, FALSE))
1745 DEBUG(D_tls) debug_printf("TLS: preloading CA bundle for server\n");
1747 if (setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, &dummy_errstr)
1749 state_server.lib_state.cabundle = TRUE;
1753 DEBUG(D_tls) debug_printf("TLS: not preloading CA bundle for server\n");
1754 #endif /* EXIM_HAVE_INOTIFY */
1757 /* If we can, preload the ciphers control string */
1759 if (opt_set_and_noexpand(tls_require_ciphers))
1761 DEBUG(D_tls) debug_printf("TLS: preloading cipher list for server\n");
1762 if (server_load_ciphers(ctx, &state_server, tls_require_ciphers,
1763 &dummy_errstr) == OK)
1764 state_server.lib_state.pri_string = TRUE;
1767 DEBUG(D_tls) debug_printf("TLS: not preloading cipher list for server\n");
1774 /* Preload whatever creds are static, onto a transport. The client can then
1775 just copy the pointer as it starts up.
1776 Called from the daemon after a cache-invalidate with watch set; called from
1777 a queue-run startup with watch clear. */
1780 tls_client_creds_init(transport_instance * t, BOOL watch)
1782 smtp_transport_options_block * ob = t->options_block;
1783 exim_openssl_state_st tpt_dummy_state;
1784 host_item * dummy_host = (host_item *)1;
1785 uschar * dummy_errstr;
1790 ob->tls_preload = null_tls_preload;
1791 if (lib_ctx_new(&ctx, dummy_host, &dummy_errstr) != OK)
1793 ob->tls_preload.lib_ctx = ctx;
1795 tpt_dummy_state.lib_state = ob->tls_preload;
1797 if (opt_unset_or_noexpand(tls_dhparam))
1799 DEBUG(D_tls) debug_printf("TLS: preloading DH params for transport '%s'\n", t->name);
1800 if (init_dh(ctx, tls_dhparam, NULL, &dummy_errstr))
1801 ob->tls_preload.dh = TRUE;
1803 if (opt_unset_or_noexpand(tls_eccurve))
1805 DEBUG(D_tls) debug_printf("TLS: preloading ECDH curve for transport '%s'\n", t->name);
1806 if (init_ecdh(ctx, NULL, &dummy_errstr))
1807 ob->tls_preload.ecdh = TRUE;
1810 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1811 if ( opt_set_and_noexpand(ob->tls_certificate)
1812 && opt_unset_or_noexpand(ob->tls_privatekey))
1815 || ( tls_set_watch(ob->tls_certificate, FALSE)
1816 && tls_set_watch(ob->tls_privatekey, FALSE)
1819 uschar * pkey = ob->tls_privatekey;
1822 debug_printf("TLS: preloading client certs for transport '%s'\n",t->name);
1824 if ( tls_add_certfile(ctx, &tpt_dummy_state, ob->tls_certificate,
1826 && tls_add_pkeyfile(ctx, &tpt_dummy_state,
1827 pkey ? pkey : ob->tls_certificate,
1830 ob->tls_preload.conn_certs = TRUE;
1835 debug_printf("TLS: not preloading client certs, for transport '%s'\n", t->name);
1838 if ( opt_set_and_noexpand(ob->tls_verify_certificates)
1839 && opt_unset_or_noexpand(ob->tls_crl))
1842 || tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
1843 && tls_set_watch(ob->tls_verify_certificates, FALSE)
1844 && tls_set_watch(ob->tls_crl, FALSE)
1848 debug_printf("TLS: preloading CA bundle for transport '%s'\n", t->name);
1850 if (setup_certs(ctx, ob->tls_verify_certificates,
1851 ob->tls_crl, dummy_host, &dummy_errstr) == OK)
1852 ob->tls_preload.cabundle = TRUE;
1857 debug_printf("TLS: not preloading CA bundle, for transport '%s'\n", t->name);
1859 #endif /*EXIM_HAVE_INOTIFY*/
1863 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1864 /* Invalidate the creds cached, by dropping the current ones.
1865 Call when we notice one of the source files has changed. */
1868 tls_server_creds_invalidate(void)
1870 SSL_CTX_free(state_server.lib_state.lib_ctx);
1871 state_server.lib_state = null_tls_preload;
1876 tls_client_creds_invalidate(transport_instance * t)
1878 smtp_transport_options_block * ob = t->options_block;
1879 SSL_CTX_free(ob->tls_preload.lib_ctx);
1880 ob->tls_preload = null_tls_preload;
1886 tls_server_creds_invalidate(void)
1890 tls_client_creds_invalidate(transport_instance * t)
1893 #endif /*EXIM_HAVE_INOTIFY*/
1897 #ifndef DISABLE_OCSP
1899 x509_store_dump_cert_s_names(X509_STORE * store)
1901 STACK_OF(X509_OBJECT) * roots= store->objs;
1902 static uschar name[256];
1904 for (int i= 0; i < sk_X509_OBJECT_num(roots); i++)
1906 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
1907 if(tmp_obj->type == X509_LU_X509)
1909 X509_NAME * sn = X509_get_subject_name(tmp_obj->data.x509);
1910 if (X509_NAME_oneline(sn, CS name, sizeof(name)))
1912 name[sizeof(name)-1] = '\0';
1913 debug_printf(" %s\n", name);
1922 #ifndef DISABLE_TLS_RESUME
1923 /* Manage the keysets used for encrypting the session tickets, on the server. */
1925 typedef struct { /* Session ticket encryption key */
1928 const EVP_CIPHER * aes_cipher;
1929 uschar aes_key[32]; /* size needed depends on cipher. aes_128 implies 128/8 = 16? */
1930 const EVP_MD * hmac_hash;
1931 uschar hmac_key[16];
1936 static exim_stek exim_tk; /* current key */
1937 static exim_stek exim_tk_old; /* previous key */
1942 time_t t = time(NULL);
1944 if (exim_tk.name[0])
1946 if (exim_tk.renew >= t) return;
1947 exim_tk_old = exim_tk;
1950 if (f.running_in_test_harness) ssl_session_timeout = 6;
1952 DEBUG(D_tls) debug_printf("OpenSSL: %s STEK\n", exim_tk.name[0] ? "rotating" : "creating");
1953 if (RAND_bytes(exim_tk.aes_key, sizeof(exim_tk.aes_key)) <= 0) return;
1954 if (RAND_bytes(exim_tk.hmac_key, sizeof(exim_tk.hmac_key)) <= 0) return;
1955 if (RAND_bytes(exim_tk.name+1, sizeof(exim_tk.name)-1) <= 0) return;
1957 exim_tk.name[0] = 'E';
1958 exim_tk.aes_cipher = EVP_aes_256_cbc();
1959 exim_tk.hmac_hash = EVP_sha256();
1960 exim_tk.expire = t + ssl_session_timeout;
1961 exim_tk.renew = t + ssl_session_timeout/2;
1967 if (!exim_tk.name[0]) return NULL;
1972 tk_find(const uschar * name)
1974 return memcmp(name, exim_tk.name, sizeof(exim_tk.name)) == 0 ? &exim_tk
1975 : memcmp(name, exim_tk_old.name, sizeof(exim_tk_old.name)) == 0 ? &exim_tk_old
1979 /* Callback for session tickets, on server */
1981 ticket_key_callback(SSL * ssl, uschar key_name[16],
1982 uschar * iv, EVP_CIPHER_CTX * c_ctx, HMAC_CTX * hctx, int enc)
1984 tls_support * tlsp = state_server.tlsp;
1989 DEBUG(D_tls) debug_printf("ticket_key_callback: create new session\n");
1990 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
1992 if (RAND_bytes(iv, EVP_MAX_IV_LENGTH) <= 0)
1993 return -1; /* insufficient random */
1995 if (!(key = tk_current())) /* current key doesn't exist or isn't valid */
1996 return 0; /* key couldn't be created */
1997 memcpy(key_name, key->name, 16);
1998 DEBUG(D_tls) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - time(NULL));
2000 /*XXX will want these dependent on the ssl session strength */
2001 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
2002 key->hmac_hash, NULL);
2003 EVP_EncryptInit_ex(c_ctx, key->aes_cipher, NULL, key->aes_key, iv);
2005 DEBUG(D_tls) debug_printf("ticket created\n");
2010 time_t now = time(NULL);
2012 DEBUG(D_tls) debug_printf("ticket_key_callback: retrieve session\n");
2013 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
2015 if (!(key = tk_find(key_name)) || key->expire < now)
2019 debug_printf("ticket not usable (%s)\n", key ? "expired" : "not found");
2020 if (key) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - now);
2025 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
2026 key->hmac_hash, NULL);
2027 EVP_DecryptInit_ex(c_ctx, key->aes_cipher, NULL, key->aes_key, iv);
2029 DEBUG(D_tls) debug_printf("ticket usable, STEK expire " TIME_T_FMT "\n", key->expire - now);
2031 /* The ticket lifetime and renewal are the same as the STEK lifetime and
2032 renewal, which is overenthusiastic. A factor of, say, 3x longer STEK would
2033 be better. To do that we'd have to encode ticket lifetime in the name as
2034 we don't yet see the restored session. Could check posthandshake for TLS1.3
2035 and trigger a new ticket then, but cannot do that for TLS1.2 */
2036 return key->renew < now ? 2 : 1;
2044 setup_cert_verify(SSL_CTX * ctx, BOOL optional,
2045 int (*cert_vfy_cb)(int, X509_STORE_CTX *))
2047 /* If verification is optional, don't fail if no certificate */
2049 SSL_CTX_set_verify(ctx,
2050 SSL_VERIFY_PEER | (optional ? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
2055 /*************************************************
2056 * Callback to handle SNI *
2057 *************************************************/
2059 /* Called when acting as server during the TLS session setup if a Server Name
2060 Indication extension was sent by the client.
2062 API documentation is OpenSSL s_server.c implementation.
2065 s SSL* of the current session
2066 ad unknown (part of OpenSSL API) (unused)
2067 arg Callback of "our" registered data
2069 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
2071 XXX might need to change to using ClientHello callback,
2072 per https://www.openssl.org/docs/manmaster/man3/SSL_client_hello_cb_fn.html
2075 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2077 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
2079 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
2080 exim_openssl_state_st *state = (exim_openssl_state_st *) arg;
2082 int old_pool = store_pool;
2083 uschar * dummy_errstr;
2086 return SSL_TLSEXT_ERR_OK;
2088 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
2089 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
2091 /* Make the extension value available for expansion */
2092 store_pool = POOL_PERM;
2093 tls_in.sni = string_copy_taint(US servername, TRUE);
2094 store_pool = old_pool;
2096 if (!reexpand_tls_files_for_sni)
2097 return SSL_TLSEXT_ERR_OK;
2099 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
2100 not confident that memcpy wouldn't break some internal reference counting.
2101 Especially since there's a references struct member, which would be off. */
2103 if (lib_ctx_new(&server_sni, NULL, &dummy_errstr) != OK)
2106 /* Not sure how many of these are actually needed, since SSL object
2107 already exists. Might even need this selfsame callback, for reneg? */
2110 SSL_CTX * ctx = state_server.lib_state.lib_ctx;
2111 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(ctx));
2112 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(ctx));
2113 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(ctx));
2114 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(ctx));
2115 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
2116 SSL_CTX_set_tlsext_servername_arg(server_sni, state);
2119 if ( !init_dh(server_sni, state->dhparam, NULL, &dummy_errstr)
2120 || !init_ecdh(server_sni, NULL, &dummy_errstr)
2124 if ( state->server_cipher_list
2125 && !SSL_CTX_set_cipher_list(server_sni, CS state->server_cipher_list))
2128 #ifndef DISABLE_OCSP
2129 if (state->u_ocsp.server.file)
2131 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
2132 SSL_CTX_set_tlsext_status_arg(server_sni, state);
2138 if ( !expand_check(tls_verify_certificates, US"tls_verify_certificates",
2139 &expcerts, &dummy_errstr)
2140 || (rc = setup_certs(server_sni, expcerts, tls_crl, NULL,
2141 &dummy_errstr)) != OK)
2144 if (expcerts && *expcerts)
2145 setup_cert_verify(server_sni, FALSE, verify_callback_server);
2148 /* do this after setup_certs, because this can require the certs for verifying
2149 OCSP information. */
2150 if ((rc = tls_expand_session_files(server_sni, state, &dummy_errstr)) != OK)
2153 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
2154 SSL_set_SSL_CTX(s, server_sni);
2155 return SSL_TLSEXT_ERR_OK;
2157 bad: return SSL_TLSEXT_ERR_ALERT_FATAL;
2159 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
2164 #ifdef EXIM_HAVE_ALPN
2165 /*************************************************
2166 * Callback to handle ALPN *
2167 *************************************************/
2169 /* Called on server if tls_alpn nonblank after expansion,
2170 when client offers ALPN, after the SNI callback.
2171 If set and not matching the list then we dump the connection */
2174 tls_server_alpn_cb(SSL *ssl, const uschar ** out, uschar * outlen,
2175 const uschar * in, unsigned int inlen, void * arg)
2177 server_seen_alpn = TRUE;
2180 debug_printf("Received TLS ALPN offer:");
2181 for (int pos = 0, siz; pos < inlen; pos += siz+1)
2184 if (pos + 1 + siz > inlen) siz = inlen - pos - 1;
2185 debug_printf(" '%.*s'", siz, in + pos + 1);
2187 debug_printf(". Our list: '%s'\n", tls_alpn);
2190 /* Look for an acceptable ALPN */
2192 if ( inlen > 1 /* at least one name */
2193 && in[0]+1 == inlen /* filling the vector, so exactly one name */
2196 const uschar * list = tls_alpn;
2198 for (uschar * name; name = string_nextinlist(&list, &sep, NULL, 0); )
2199 if (Ustrncmp(in+1, name, in[0]) == 0)
2201 *out = in+1; /* we checked for exactly one, so can just point to it */
2203 return SSL_TLSEXT_ERR_OK; /* use ALPN */
2207 /* More than one name from clilent, or name did not match our list. */
2209 /* This will be fatal to the TLS conn; would be nice to kill TCP also.
2210 Maybe as an option in future; for now leave control to the config (must-tls). */
2212 DEBUG(D_tls) debug_printf("TLS ALPN rejected\n");
2213 return SSL_TLSEXT_ERR_ALERT_FATAL;
2215 #endif /* EXIM_HAVE_ALPN */
2219 #ifndef DISABLE_OCSP
2221 /*************************************************
2222 * Callback to handle OCSP Stapling *
2223 *************************************************/
2225 /* Called when acting as server during the TLS session setup if the client
2226 requests OCSP information with a Certificate Status Request.
2228 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
2234 tls_server_stapling_cb(SSL *s, void *arg)
2236 const exim_openssl_state_st * state = arg;
2237 ocsp_resplist * olist = state->u_ocsp.server.olist;
2238 uschar * response_der; /*XXX blob */
2239 int response_der_len;
2242 debug_printf("Received TLS status request (OCSP stapling); %s response list\n",
2243 olist ? "have" : "lack");
2245 tls_in.ocsp = OCSP_NOT_RESP;
2247 return SSL_TLSEXT_ERR_NOACK;
2249 #ifdef EXIM_HAVE_OPESSL_GET0_SERIAL
2251 const X509 * cert_sent = SSL_get_certificate(s);
2252 const ASN1_INTEGER * cert_serial = X509_get0_serialNumber(cert_sent);
2253 const BIGNUM * cert_bn = ASN1_INTEGER_to_BN(cert_serial, NULL);
2255 for (; olist; olist = olist->next)
2257 OCSP_BASICRESP * bs = OCSP_response_get1_basic(olist->resp);
2258 const OCSP_SINGLERESP * single = OCSP_resp_get0(bs, 0);
2259 const OCSP_CERTID * cid = OCSP_SINGLERESP_get0_id(single);
2260 ASN1_INTEGER * res_cert_serial;
2261 const BIGNUM * resp_bn;
2262 ASN1_OCTET_STRING * res_cert_iNameHash;
2265 (void) OCSP_id_get0_info(&res_cert_iNameHash, NULL, NULL, &res_cert_serial,
2266 (OCSP_CERTID *) cid);
2267 resp_bn = ASN1_INTEGER_to_BN(res_cert_serial, NULL);
2271 debug_printf("cert serial: %s\n", BN_bn2hex(cert_bn));
2272 debug_printf("resp serial: %s\n", BN_bn2hex(resp_bn));
2275 if (BN_cmp(cert_bn, resp_bn) == 0)
2277 DEBUG(D_tls) debug_printf("matched serial for ocsp\n");
2279 /*XXX TODO: check the rest of the list for duplicate matches.
2280 If any, need to also check the Issuer Name hash.
2281 Without this, we will provide the wrong status in the case of
2286 DEBUG(D_tls) debug_printf("not match serial for ocsp\n");
2290 DEBUG(D_tls) debug_printf("failed to find match for ocsp\n");
2291 return SSL_TLSEXT_ERR_NOACK;
2297 DEBUG(D_tls) debug_printf("OpenSSL version too early to support multi-leaf OCSP\n");
2298 return SSL_TLSEXT_ERR_NOACK;
2302 /*XXX could we do the i2d earlier, rather than during the callback? */
2303 response_der = NULL;
2304 response_der_len = i2d_OCSP_RESPONSE(olist->resp, &response_der);
2305 if (response_der_len <= 0)
2306 return SSL_TLSEXT_ERR_NOACK;
2308 SSL_set_tlsext_status_ocsp_resp(state_server.lib_state.lib_ssl,
2309 response_der, response_der_len);
2310 tls_in.ocsp = OCSP_VFIED;
2311 return SSL_TLSEXT_ERR_OK;
2316 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
2318 BIO_printf(bp, "\t%s: ", str);
2319 ASN1_GENERALIZEDTIME_print(bp, time);
2324 tls_client_stapling_cb(SSL *s, void *arg)
2326 exim_openssl_state_st * cbinfo = arg;
2327 const unsigned char * p;
2329 OCSP_RESPONSE * rsp;
2330 OCSP_BASICRESP * bs;
2333 DEBUG(D_tls) debug_printf("Received TLS status callback (OCSP stapling):\n");
2334 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
2337 /* Expect this when we requested ocsp but got none */
2338 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
2339 log_write(0, LOG_MAIN, "Required TLS certificate status not received");
2341 DEBUG(D_tls) debug_printf(" null\n");
2342 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2345 if (!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
2347 tls_out.ocsp = OCSP_FAILED; /*XXX should use tlsp-> to permit concurrent outbound */
2348 if (LOGGING(tls_cipher))
2349 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
2351 DEBUG(D_tls) debug_printf(" parse error\n");
2355 if (!(bs = OCSP_response_get1_basic(rsp)))
2357 tls_out.ocsp = OCSP_FAILED;
2358 if (LOGGING(tls_cipher))
2359 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
2361 DEBUG(D_tls) debug_printf(" error parsing response\n");
2362 OCSP_RESPONSE_free(rsp);
2366 /* We'd check the nonce here if we'd put one in the request. */
2367 /* However that would defeat cacheability on the server so we don't. */
2369 /* This section of code reworked from OpenSSL apps source;
2370 The OpenSSL Project retains copyright:
2371 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
2375 #ifndef EXIM_HAVE_OCSP_RESP_COUNT
2376 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
2379 DEBUG(D_tls) bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
2381 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
2383 /* Use the chain that verified the server cert to verify the stapled info */
2384 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
2386 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
2387 cbinfo->u_ocsp.client.verify_store, OCSP_NOEXPLICIT)) <= 0)
2388 if (ERR_peek_error())
2390 tls_out.ocsp = OCSP_FAILED;
2391 if (LOGGING(tls_cipher)) log_write(0, LOG_MAIN,
2392 "Received TLS cert status response, itself unverifiable: %s",
2393 ERR_reason_error_string(ERR_peek_error()));
2394 BIO_printf(bp, "OCSP response verify failure\n");
2395 ERR_print_errors(bp);
2396 OCSP_RESPONSE_print(bp, rsp, 0);
2400 DEBUG(D_tls) debug_printf("no explicit trust for OCSP signing"
2401 " in the root CA certificate; ignoring\n");
2403 DEBUG(D_tls) debug_printf("OCSP response well-formed and signed OK\n");
2405 /*XXX So we have a good stapled OCSP status. How do we know
2406 it is for the cert of interest? OpenSSL 1.1.0 has a routine
2407 OCSP_resp_find_status() which matches on a cert id, which presumably
2408 we should use. Making an id needs OCSP_cert_id_new(), which takes
2409 issuerName, issuerKey, serialNumber. Are they all in the cert?
2411 For now, carry on blindly accepting the resp. */
2414 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
2415 OCSP_resp_count(bs) - 1;
2417 sk_OCSP_SINGLERESP_num(sresp) - 1;
2421 OCSP_SINGLERESP * single = OCSP_resp_get0(bs, idx);
2423 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
2425 /*XXX so I can see putting a loop in here to handle a rsp with >1 singleresp
2426 - but what happens with a GnuTLS-style input?
2428 we could do with a debug label for each singleresp
2429 - it has a certID with a serialNumber, but I see no API to get that
2431 status = OCSP_single_get0_status(single, &reason, &rev,
2432 &thisupd, &nextupd);
2434 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
2435 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
2436 if (!OCSP_check_validity(thisupd, nextupd,
2437 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
2439 tls_out.ocsp = OCSP_FAILED;
2440 DEBUG(D_tls) ERR_print_errors(bp);
2441 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
2445 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
2446 OCSP_cert_status_str(status));
2449 case V_OCSP_CERTSTATUS_GOOD:
2450 continue; /* the idx loop */
2451 case V_OCSP_CERTSTATUS_REVOKED:
2452 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
2453 reason != -1 ? "; reason: " : "",
2454 reason != -1 ? OCSP_crl_reason_str(reason) : "");
2455 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
2458 log_write(0, LOG_MAIN,
2459 "Server certificate status unknown, in OCSP stapling");
2467 tls_out.ocsp = OCSP_VFIED;
2471 tls_out.ocsp = OCSP_FAILED;
2472 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2477 OCSP_RESPONSE_free(rsp);
2480 #endif /*!DISABLE_OCSP*/
2483 /*************************************************
2484 * Initialize for TLS *
2485 *************************************************/
2486 /* Called from both server and client code, to do preliminary initialization
2487 of the library. We allocate and return a context structure.
2490 host connected host, if client; NULL if server
2491 ob transport options block, if client; NULL if server
2492 ocsp_file file of stapling info (server); flag for require ocsp (client)
2493 addr address if client; NULL if server (for some randomness)
2494 caller_state place to put pointer to allocated state-struct
2495 errstr error string pointer
2497 Returns: OK/DEFER/FAIL
2501 tls_init(host_item * host, smtp_transport_options_block * ob,
2502 #ifndef DISABLE_OCSP
2505 address_item *addr, exim_openssl_state_st ** caller_state,
2510 exim_openssl_state_st * state;
2513 if (host) /* client */
2515 state = store_malloc(sizeof(exim_openssl_state_st));
2516 memset(state, 0, sizeof(*state));
2517 state->certificate = ob->tls_certificate;
2518 state->privatekey = ob->tls_privatekey;
2519 state->is_server = FALSE;
2520 state->dhparam = NULL;
2521 state->lib_state = ob->tls_preload;
2525 state = &state_server;
2526 state->certificate = tls_certificate;
2527 state->privatekey = tls_privatekey;
2528 state->is_server = TRUE;
2529 state->dhparam = tls_dhparam;
2530 state->lib_state = state_server.lib_state;
2536 if (!state->lib_state.pri_string)
2537 state->server_cipher_list = NULL;
2539 #ifndef DISABLE_EVENT
2540 state->event_action = NULL;
2545 /* It turns out that we need to seed the random number generator this early in
2546 order to get the full complement of ciphers to work. It took me roughly a day
2547 of work to discover this by experiment.
2549 On systems that have /dev/urandom, SSL may automatically seed itself from
2550 there. Otherwise, we have to make something up as best we can. Double check
2553 Although we likely called this before, at daemon startup, this is a chance
2554 to mix in further variable info (time, pid) if needed. */
2556 if (!lib_rand_init(addr))
2557 return tls_error(US"RAND_status", host,
2558 US"unable to seed random number generator", errstr);
2560 /* Apply administrator-supplied work-arounds.
2561 Historically we applied just one requested option,
2562 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
2563 moved to an administrator-controlled list of options to specify and
2564 grandfathered in the first one as the default value for "openssl_options".
2566 No OpenSSL version number checks: the options we accept depend upon the
2567 availability of the option value macros from OpenSSL. */
2570 if (!tls_openssl_options_parse(openssl_options, &init_options))
2571 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
2573 /* Create a context.
2574 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
2575 negotiation in the different methods; as far as I can tell, the only
2576 *_{server,client}_method which allows negotiation is SSLv23, which exists even
2577 when OpenSSL is built without SSLv2 support.
2578 By disabling with openssl_options, we can let admins re-enable with the
2581 if (!(ctx = state->lib_state.lib_ctx))
2583 if ((rc = lib_ctx_new(&ctx, host, errstr)) != OK)
2585 state->lib_state.lib_ctx = ctx;
2588 #ifndef DISABLE_TLS_RESUME
2589 tlsp->resumption = RESUME_SUPPORTED;
2593 #ifndef DISABLE_TLS_RESUME
2594 /* Should the server offer session resumption? */
2595 if (!host && verify_check_host(&tls_resumption_hosts) == OK)
2597 DEBUG(D_tls) debug_printf("tls_resumption_hosts overrides openssl_options\n");
2598 init_options &= ~SSL_OP_NO_TICKET;
2599 tlsp->resumption |= RESUME_SERVER_TICKET; /* server will give ticket on request */
2600 tlsp->host_resumable = TRUE;
2604 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
2605 if (!(SSL_CTX_set_options(ctx, init_options)))
2606 return tls_error(string_sprintf(
2607 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
2610 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
2612 /* We'd like to disable session cache unconditionally, but foolish Outlook
2613 Express clients then give up the first TLS connection and make a second one
2614 (which works). Only when there is an IMAP service on the same machine.
2615 Presumably OE is trying to use the cache for A on B. Leave it enabled for
2616 now, until we work out a decent way of presenting control to the config. It
2617 will never be used because we use a new context every time. */
2619 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
2622 /* Initialize with DH parameters if supplied */
2623 /* Initialize ECDH temp key parameter selection */
2625 if (state->lib_state.dh)
2626 { DEBUG(D_tls) debug_printf("TLS: DH params were preloaded\n"); }
2628 if (!init_dh(ctx, state->dhparam, host, errstr)) return DEFER;
2630 if (state->lib_state.ecdh)
2631 { DEBUG(D_tls) debug_printf("TLS: ECDH curve was preloaded\n"); }
2633 if (!init_ecdh(ctx, host, errstr)) return DEFER;
2635 /* Set up certificate and key (and perhaps OCSP info) */
2637 if (state->lib_state.conn_certs)
2640 debug_printf("TLS: %s certs were preloaded\n", host ? "client":"server");
2644 #ifndef DISABLE_OCSP
2647 state->u_ocsp.server.file = ocsp_file;
2648 state->u_ocsp.server.file_expanded = NULL;
2649 state->u_ocsp.server.olist = NULL;
2652 if ((rc = tls_expand_session_files(ctx, state, errstr)) != OK) return rc;
2655 /* If we need to handle SNI or OCSP, do so */
2657 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2658 # ifndef DISABLE_OCSP
2659 if (!(state->verify_stack = sk_X509_new_null()))
2661 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
2666 if (!host) /* server */
2668 # ifndef DISABLE_OCSP
2669 /* We check u_ocsp.server.file, not server.olist, because we care about if
2670 the option exists, not what the current expansion might be, as SNI might
2671 change the certificate and OCSP file in use between now and the time the
2672 callback is invoked. */
2673 if (state->u_ocsp.server.file)
2675 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
2676 SSL_CTX_set_tlsext_status_arg(ctx, state);
2679 /* We always do this, so that $tls_sni is available even if not used in
2681 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
2682 SSL_CTX_set_tlsext_servername_arg(ctx, state);
2684 # ifdef EXIM_HAVE_ALPN
2685 if (tls_alpn && *tls_alpn)
2688 if ( expand_check(tls_alpn, US"tls_alpn", &exp_alpn, errstr)
2689 && *exp_alpn && !isblank(*exp_alpn))
2691 tls_alpn = exp_alpn; /* subprocess so ok to overwrite */
2692 SSL_CTX_set_alpn_select_cb(ctx, tls_server_alpn_cb, state);
2699 # ifndef DISABLE_OCSP
2701 if(ocsp_file) /* wanting stapling */
2703 if (!(state->u_ocsp.client.verify_store = X509_STORE_new()))
2705 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
2708 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
2709 SSL_CTX_set_tlsext_status_arg(ctx, state);
2714 state->verify_cert_hostnames = NULL;
2716 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
2717 /* Set up the RSA callback */
2718 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
2721 /* Finally, set the session cache timeout, and we are done.
2722 The period appears to be also used for (server-generated) session tickets */
2724 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
2725 DEBUG(D_tls) debug_printf("Initialized TLS\n");
2727 *caller_state = state;
2735 /*************************************************
2736 * Get name of cipher in use *
2737 *************************************************/
2740 Argument: pointer to an SSL structure for the connection
2741 pointer to number of bits for cipher
2742 Returns: pointer to allocated string in perm-pool
2746 construct_cipher_name(SSL * ssl, const uschar * ver, int * bits)
2748 int pool = store_pool;
2749 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
2750 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
2751 the accessor functions use const in the prototype. */
2753 const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
2756 SSL_CIPHER_get_bits(c, bits);
2758 store_pool = POOL_PERM;
2759 s = string_sprintf("%s:%s:%u", ver, SSL_CIPHER_get_name(c), *bits);
2761 DEBUG(D_tls) debug_printf("Cipher: %s\n", s);
2766 /* Get IETF-standard name for ciphersuite.
2767 Argument: pointer to an SSL structure for the connection
2768 Returns: pointer to string
2771 static const uschar *
2772 cipher_stdname_ssl(SSL * ssl)
2774 #ifdef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
2775 return CUS SSL_CIPHER_standard_name(SSL_get_current_cipher(ssl));
2777 ushort id = 0xffff & SSL_CIPHER_get_id(SSL_get_current_cipher(ssl));
2778 return cipher_stdname(id >> 8, id & 0xff);
2783 static const uschar *
2784 tlsver_name(SSL * ssl)
2787 int pool = store_pool;
2789 store_pool = POOL_PERM;
2790 s = string_copy(US SSL_get_version(ssl));
2792 if ((p = Ustrchr(s, 'v'))) /* TLSv1.2 -> TLS1.2 */
2793 for (;; p++) if (!(*p = p[1])) break;
2799 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned siz)
2801 /*XXX we might consider a list-of-certs variable for the cert chain.
2802 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
2803 in list-handling functions, also consider the difference between the entire
2804 chain and the elements sent by the peer. */
2806 tlsp->peerdn = NULL;
2808 /* Will have already noted peercert on a verify fail; possibly not the leaf */
2809 if (!tlsp->peercert)
2810 tlsp->peercert = SSL_get_peer_certificate(ssl);
2811 /* Beware anonymous ciphers which lead to server_cert being NULL */
2813 if (!X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, siz))
2814 { DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n"); }
2817 int oldpool = store_pool;
2819 peerdn[siz-1] = '\0'; /* paranoia */
2820 store_pool = POOL_PERM;
2821 tlsp->peerdn = string_copy(peerdn);
2822 store_pool = oldpool;
2824 /* We used to set CV in the cert-verify callbacks (either plain or dane)
2825 but they don't get called on session-resumption. So use the official
2826 interface, which uses the resumed value. Unfortunately this claims verified
2827 when it actually failed but we're in try-verify mode, due to us wanting the
2828 knowlege that it failed so needing to have the callback and forcing a
2829 permissive return. If we don't force it, the TLS startup is failed.
2830 The extra bit of information is set in verify_override in the cb, stashed
2831 for resumption next to the TLS session, and used here. */
2833 if (!tlsp->verify_override)
2834 tlsp->certificate_verified =
2836 tlsp->dane_verified ||
2838 SSL_get_verify_result(ssl) == X509_V_OK;
2846 /*************************************************
2847 * Set up for verifying certificates *
2848 *************************************************/
2850 #ifndef DISABLE_OCSP
2851 /* Load certs from file, return TRUE on success */
2854 chain_from_pem_file(const uschar * file, STACK_OF(X509) ** vp)
2857 STACK_OF(X509) * verify_stack = *vp;
2860 while (sk_X509_num(verify_stack) > 0)
2861 X509_free(sk_X509_pop(verify_stack));
2863 verify_stack = sk_X509_new_null();
2865 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
2866 for (X509 * x; x = PEM_read_bio_X509(bp, NULL, 0, NULL); )
2867 sk_X509_push(verify_stack, x);
2876 /* Called by both client and server startup; on the server possibly
2877 repeated after a Server Name Indication.
2880 sctx SSL_CTX* to initialise
2881 certs certs file, expanded
2882 crl CRL file or NULL
2883 host NULL in a server; the remote host in a client
2884 errstr error string pointer
2886 Returns: OK/DEFER/FAIL
2890 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host,
2893 uschar *expcerts, *expcrl;
2895 if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
2897 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
2899 if (expcerts && *expcerts)
2901 /* Tell the library to use its compiled-in location for the system default
2902 CA bundle. Then add the ones specified in the config, if any. */
2904 if (!SSL_CTX_set_default_verify_paths(sctx))
2905 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
2907 if (Ustrcmp(expcerts, "system") != 0 && Ustrncmp(expcerts, "system,", 7) != 0)
2909 struct stat statbuf;
2911 if (Ustat(expcerts, &statbuf) < 0)
2913 log_write(0, LOG_MAIN|LOG_PANIC,
2914 "failed to stat %s for certificates", expcerts);
2920 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
2921 { file = NULL; dir = expcerts; }
2924 STACK_OF(X509) * verify_stack =
2925 #ifndef DISABLE_OCSP
2926 !host ? state_server.verify_stack :
2929 STACK_OF(X509) ** vp = &verify_stack;
2931 file = expcerts; dir = NULL;
2932 #ifndef DISABLE_OCSP
2933 /* In the server if we will be offering an OCSP proof, load chain from
2934 file for verifying the OCSP proof at load time. */
2936 /*XXX Glitch! The file here is tls_verify_certs: the chain for verifying the client cert.
2937 This is inconsistent with the need to verify the OCSP proof of the server cert.
2940 && statbuf.st_size > 0
2941 && state_server.u_ocsp.server.file
2942 && !chain_from_pem_file(file, vp)
2945 log_write(0, LOG_MAIN|LOG_PANIC,
2946 "failed to load cert chain from %s", file);
2952 /* If a certificate file is empty, the load function fails with an
2953 unhelpful error message. If we skip it, we get the correct behaviour (no
2954 certificates are recognized, but the error message is still misleading (it
2955 says no certificate was supplied). But this is better. */
2957 if ( (!file || statbuf.st_size > 0)
2958 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
2959 return tls_error(US"SSL_CTX_load_verify_locations",
2960 host, NULL, errstr);
2962 /* On the server load the list of CAs for which we will accept certs, for
2963 sending to the client. This is only for the one-file
2964 tls_verify_certificates variant.
2965 If a list isn't loaded into the server, but some verify locations are set,
2966 the server end appears to make a wildcard request for client certs.
2967 Meanwhile, the client library as default behaviour *ignores* the list
2968 we send over the wire - see man SSL_CTX_set_client_cert_cb.
2969 Because of this, and that the dir variant is likely only used for
2970 the public-CA bundle (not for a private CA), not worth fixing. */
2974 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
2975 int i = sk_X509_NAME_num(names);
2977 if (!host) SSL_CTX_set_client_CA_list(sctx, names);
2978 DEBUG(D_tls) debug_printf("Added %d additional certificate authorit%s\n",
2979 i, i>1 ? "ies":"y");
2983 debug_printf("Added dir for additional certificate authorities\n");
2987 /* Handle a certificate revocation list. */
2989 #if OPENSSL_VERSION_NUMBER > 0x00907000L
2991 /* This bit of code is now the version supplied by Lars Mainka. (I have
2992 merely reformatted it into the Exim code style.)
2994 "From here I changed the code to add support for multiple crl's
2995 in pem format in one file or to support hashed directory entries in
2996 pem format instead of a file. This method now uses the library function
2997 X509_STORE_load_locations to add the CRL location to the SSL context.
2998 OpenSSL will then handle the verify against CA certs and CRLs by
2999 itself in the verify callback." */
3001 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
3002 if (expcrl && *expcrl)
3004 struct stat statbufcrl;
3005 if (Ustat(expcrl, &statbufcrl) < 0)
3007 log_write(0, LOG_MAIN|LOG_PANIC,
3008 "failed to stat %s for certificates revocation lists", expcrl);
3013 /* is it a file or directory? */
3015 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
3016 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
3020 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
3026 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
3028 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
3029 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
3031 /* setting the flags to check against the complete crl chain */
3033 X509_STORE_set_flags(cvstore,
3034 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
3038 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
3046 /*************************************************
3047 * Start a TLS session in a server *
3048 *************************************************/
3049 /* This is called when Exim is running as a server, after having received
3050 the STARTTLS command. It must respond to that command, and then negotiate
3054 errstr pointer to error message
3056 Returns: OK on success
3057 DEFER for errors before the start of the negotiation
3058 FAIL for errors during the negotiation; the server can't
3063 tls_server_start(uschar ** errstr)
3066 uschar * expciphers;
3067 exim_openssl_state_st * dummy_statep;
3070 static uschar peerdn[256];
3072 /* Check for previous activation */
3074 if (tls_in.active.sock >= 0)
3076 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
3077 smtp_printf("554 Already in TLS\r\n", FALSE);
3081 /* Initialize the SSL library. If it fails, it will already have logged
3084 rc = tls_init(NULL, NULL,
3085 #ifndef DISABLE_OCSP
3088 NULL, &dummy_statep, &tls_in, errstr);
3089 if (rc != OK) return rc;
3090 ctx = state_server.lib_state.lib_ctx;
3092 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
3093 were historically separated by underscores. So that I can use either form in my
3094 tests, and also for general convenience, we turn underscores into hyphens here.
3096 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
3097 for TLS 1.3 . Since we do not call it at present we get the default list:
3098 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
3101 if (state_server.lib_state.pri_string)
3102 { DEBUG(D_tls) debug_printf("TLS: cipher list was preloaded\n"); }
3105 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
3109 && (rc = server_load_ciphers(ctx, &state_server, expciphers, errstr)) != OK)
3113 /* If this is a host for which certificate verification is mandatory or
3114 optional, set up appropriately. */
3116 tls_in.certificate_verified = FALSE;
3118 tls_in.dane_verified = FALSE;
3120 server_verify_callback_called = FALSE;
3122 if (verify_check_host(&tls_verify_hosts) == OK)
3123 server_verify_optional = FALSE;
3124 else if (verify_check_host(&tls_try_verify_hosts) == OK)
3125 server_verify_optional = TRUE;
3131 if (!expand_check(tls_verify_certificates, US"tls_verify_certificates",
3134 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3136 if (state_server.lib_state.cabundle)
3137 { DEBUG(D_tls) debug_printf("TLS: CA bundle for server was preloaded\n"); }
3139 if ((rc = setup_certs(ctx, expcerts, tls_crl, NULL, errstr)) != OK)
3142 if (expcerts && *expcerts)
3143 setup_cert_verify(ctx, server_verify_optional, verify_callback_server);
3147 #ifndef DISABLE_TLS_RESUME
3148 SSL_CTX_set_tlsext_ticket_key_cb(ctx, ticket_key_callback);
3149 /* despite working, appears to always return failure, so ignoring */
3151 #ifdef OPENSSL_HAVE_NUM_TICKETS
3152 # ifndef DISABLE_TLS_RESUME
3153 SSL_CTX_set_num_tickets(ctx, tls_in.host_resumable ? 1 : 0);
3155 SSL_CTX_set_num_tickets(ctx, 0); /* send no TLS1.3 stateful-tickets */
3160 /* Prepare for new connection */
3162 if (!(ssl = SSL_new(ctx)))
3163 return tls_error(US"SSL_new", NULL, NULL, errstr);
3164 state_server.lib_state.lib_ssl = ssl;
3166 /* Warning: we used to SSL_clear(ssl) here, it was removed.
3168 * With the SSL_clear(), we get strange interoperability bugs with
3169 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
3170 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
3172 * The SSL_clear() call is to let an existing SSL* be reused, typically after
3173 * session shutdown. In this case, we have a brand new object and there's no
3174 * obvious reason to immediately clear it. I'm guessing that this was
3175 * originally added because of incomplete initialisation which the clear fixed,
3176 * in some historic release.
3179 /* Set context and tell client to go ahead, except in the case of TLS startup
3180 on connection, where outputting anything now upsets the clients and tends to
3181 make them disconnect. We need to have an explicit fflush() here, to force out
3182 the response. Other smtp_printf() calls do not need it, because in non-TLS
3183 mode, the fflush() happens when smtp_getc() is called. */
3185 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
3186 if (!tls_in.on_connect)
3188 smtp_printf("220 TLS go ahead\r\n", FALSE);
3192 /* Now negotiate the TLS session. We put our own timer on it, since it seems
3193 that the OpenSSL library doesn't. */
3195 SSL_set_wfd(ssl, fileno(smtp_out));
3196 SSL_set_rfd(ssl, fileno(smtp_in));
3197 SSL_set_accept_state(ssl);
3199 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
3202 sigalrm_seen = FALSE;
3203 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3204 rc = SSL_accept(ssl);
3209 int error = SSL_get_error(ssl, rc);
3212 case SSL_ERROR_NONE:
3215 case SSL_ERROR_ZERO_RETURN:
3216 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3217 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
3219 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
3222 tls_close(NULL, TLS_NO_SHUTDOWN);
3225 /* Handle genuine errors */
3229 int r = ERR_GET_REASON(ERR_peek_error());
3230 if ( r == SSL_R_WRONG_VERSION_NUMBER
3231 #ifdef SSL_R_VERSION_TOO_LOW
3232 || r == SSL_R_VERSION_TOO_LOW
3234 || r == SSL_R_UNKNOWN_PROTOCOL || r == SSL_R_UNSUPPORTED_PROTOCOL)
3235 s = string_sprintf("%s (%s)", s, SSL_get_version(ssl));
3236 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : s, errstr);
3241 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
3242 if (error == SSL_ERROR_SYSCALL)
3246 *errstr = US"SSL_accept: TCP connection closed by peer";
3249 DEBUG(D_tls) debug_printf(" - syscall %s\n", strerror(errno));
3251 (void) tls_error(US"SSL_accept", NULL,
3252 sigalrm_seen ? US"timed out"
3253 : ERR_peek_error() ? NULL : string_sprintf("ret %d", error),
3259 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
3260 ERR_clear_error(); /* Even success can leave errors in the stack. Seen with
3261 anon-authentication ciphersuite negotiated. */
3263 #ifndef DISABLE_TLS_RESUME
3264 if (SSL_session_reused(ssl))
3266 tls_in.resumption |= RESUME_USED;
3267 DEBUG(D_tls) debug_printf("Session reused\n");
3271 #ifdef EXIM_HAVE_ALPN
3272 /* If require-alpn, check server_seen_alpn here. Else abort TLS */
3273 if (!tls_alpn || !*tls_alpn)
3274 { DEBUG(D_tls) debug_printf("TLS: was not watching for ALPN\n"); }
3275 else if (!server_seen_alpn)
3276 if (verify_check_host(&hosts_require_alpn) == OK)
3278 /* We'd like to send a definitive Alert but OpenSSL provides no facility */
3280 tls_error(US"handshake", NULL, US"ALPN required but not negotiated", errstr);
3284 { DEBUG(D_tls) debug_printf("TLS: no ALPN presented in handshake\n"); }
3287 const uschar * name;
3289 SSL_get0_alpn_selected(ssl, &name, &len);
3291 debug_printf("ALPN negotiated: '%.*s'\n", (int)*name, name+1);
3293 debug_printf("ALPN: no protocol negotiated\n");
3298 /* TLS has been set up. Record data for the connection,
3299 adjust the input functions to read via TLS, and initialize things. */
3301 #ifdef SSL_get_extms_support
3302 tls_in.ext_master_secret = SSL_get_extms_support(ssl) == 1;
3304 peer_cert(ssl, &tls_in, peerdn, sizeof(peerdn));
3306 tls_in.ver = tlsver_name(ssl);
3307 tls_in.cipher = construct_cipher_name(ssl, tls_in.ver, &tls_in.bits);
3308 tls_in.cipher_stdname = cipher_stdname_ssl(ssl);
3313 if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)))
3314 debug_printf("Shared ciphers: %s\n", buf);
3316 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3318 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
3319 SSL_SESSION_print_keylog(bp, SSL_get_session(ssl));
3324 #ifdef EXIM_HAVE_SESSION_TICKET
3326 SSL_SESSION * ss = SSL_get_session(ssl);
3327 if (SSL_SESSION_has_ticket(ss)) /* 1.1.0 */
3328 debug_printf("The session has a ticket, life %lu seconds\n",
3329 SSL_SESSION_get_ticket_lifetime_hint(ss));
3334 /* Record the certificate we presented */
3336 X509 * crt = SSL_get_certificate(ssl);
3337 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
3340 /* Channel-binding info for authenticators
3341 See description in https://paquier.xyz/postgresql-2/channel-binding-openssl/ */
3344 size_t len = SSL_get_peer_finished(ssl, &c, 0);
3345 int old_pool = store_pool;
3347 SSL_get_peer_finished(ssl, s = store_get((int)len, FALSE), len);
3348 store_pool = POOL_PERM;
3349 tls_in.channelbinding = b64encode_taint(CUS s, (int)len, FALSE);
3350 store_pool = old_pool;
3351 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage %p\n", tls_in.channelbinding);
3354 /* Only used by the server-side tls (tls_in), including tls_getc.
3355 Client-side (tls_out) reads (seem to?) go via
3356 smtp_read_response()/ip_recv().
3357 Hence no need to duplicate for _in and _out.
3359 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
3360 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
3361 ssl_xfer_eof = ssl_xfer_error = FALSE;
3363 receive_getc = tls_getc;
3364 receive_getbuf = tls_getbuf;
3365 receive_get_cache = tls_get_cache;
3366 receive_hasc = tls_hasc;
3367 receive_ungetc = tls_ungetc;
3368 receive_feof = tls_feof;
3369 receive_ferror = tls_ferror;
3371 tls_in.active.sock = fileno(smtp_out);
3372 tls_in.active.tls_ctx = NULL; /* not using explicit ctx for server-side */
3380 tls_client_basic_ctx_init(SSL_CTX * ctx,
3381 host_item * host, smtp_transport_options_block * ob, exim_openssl_state_st * state,
3386 /* Back-compatible old behaviour if tls_verify_certificates is set but both
3387 tls_verify_hosts and tls_try_verify_hosts are not set. Check only the specified
3388 host patterns if one of them is set with content. */
3390 if ( ( ( !ob->tls_verify_hosts || !ob->tls_verify_hosts
3391 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3393 && ( !ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts
3394 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3397 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
3399 client_verify_optional = FALSE;
3400 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
3401 client_verify_optional = TRUE;
3407 if (!expand_check(ob->tls_verify_certificates, US"tls_verify_certificates",
3410 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3412 if (state->lib_state.cabundle)
3413 { DEBUG(D_tls) debug_printf("TLS: CA bundle was preloaded\n"); }
3415 if ((rc = setup_certs(ctx, expcerts, ob->tls_crl, host, errstr)) != OK)
3418 if (expcerts && *expcerts)
3419 setup_cert_verify(ctx, client_verify_optional, verify_callback_client);
3422 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
3424 state->verify_cert_hostnames =
3426 string_domain_utf8_to_alabel(host->certname, NULL);
3430 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
3431 state->verify_cert_hostnames);
3439 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
3442 const char * hostnames[2] = { CS host->name, NULL };
3445 if (DANESSL_init(ssl, NULL, hostnames) != 1)
3446 return tls_error(US"hostnames load", host, NULL, errstr);
3448 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
3449 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
3450 ) if (rr->type == T_TLSA && rr->size > 3)
3452 const uschar * p = rr->data;
3453 uint8_t usage, selector, mtype;
3454 const char * mdname;
3458 /* Only DANE-TA(2) and DANE-EE(3) are supported */
3459 if (usage != 2 && usage != 3) continue;
3466 default: continue; /* Only match-types 0, 1, 2 are supported */
3467 case 0: mdname = NULL; break;
3468 case 1: mdname = "sha256"; break;
3469 case 2: mdname = "sha512"; break;
3473 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
3476 return tls_error(US"tlsa load", host, NULL, errstr);
3477 case 0: /* action not taken */
3481 tls_out.tlsa_usage |= 1<<usage;
3487 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
3490 #endif /*SUPPORT_DANE*/
3494 #ifndef DISABLE_TLS_RESUME
3495 /* On the client, get any stashed session for the given IP from hints db
3496 and apply it to the ssl-connection for attempted resumption. */
3499 tls_retrieve_session(tls_support * tlsp, SSL * ssl, const uschar * key)
3501 tlsp->resumption |= RESUME_SUPPORTED;
3502 if (tlsp->host_resumable)
3504 dbdata_tls_session * dt;
3506 open_db dbblock, * dbm_file;
3508 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
3509 DEBUG(D_tls) debug_printf("checking for resumable session for %s\n", key);
3510 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3512 /* key for the db is the IP */
3513 if ((dt = dbfn_read_with_length(dbm_file, key, &len)))
3515 SSL_SESSION * ss = NULL;
3516 const uschar * sess_asn1 = dt->session;
3518 len -= sizeof(dbdata_tls_session);
3519 if (!(d2i_SSL_SESSION(&ss, &sess_asn1, (long)len)))
3523 ERR_error_string_n(ERR_get_error(),
3524 ssl_errstring, sizeof(ssl_errstring));
3525 debug_printf("decoding session: %s\n", ssl_errstring);
3530 unsigned long lifetime =
3531 #ifdef EXIM_HAVE_SESSION_TICKET
3532 SSL_SESSION_get_ticket_lifetime_hint(ss);
3533 #else /* Use, fairly arbitrilarily, what we as server would */
3534 f.running_in_test_harness ? 6 : ssl_session_timeout;
3536 if (lifetime + dt->time_stamp < time(NULL))
3538 DEBUG(D_tls) debug_printf("session expired\n");
3539 dbfn_delete(dbm_file, key);
3541 else if (!SSL_set_session(ssl, ss))
3545 ERR_error_string_n(ERR_get_error(),
3546 ssl_errstring, sizeof(ssl_errstring));
3547 debug_printf("applying session to ssl: %s\n", ssl_errstring);
3552 DEBUG(D_tls) debug_printf("good session\n");
3553 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
3554 tlsp->verify_override = dt->verify_override;
3555 tlsp->ocsp = dt->ocsp;
3560 DEBUG(D_tls) debug_printf("no session record\n");
3561 dbfn_close(dbm_file);
3567 /* On the client, save the session for later resumption */
3570 tls_save_session_cb(SSL * ssl, SSL_SESSION * ss)
3572 exim_openssl_state_st * cbinfo = SSL_get_ex_data(ssl, tls_exdata_idx);
3575 DEBUG(D_tls) debug_printf("tls_save_session_cb\n");
3577 if (!cbinfo || !(tlsp = cbinfo->tlsp)->host_resumable) return 0;
3579 # ifdef OPENSSL_HAVE_NUM_TICKETS
3580 if (SSL_SESSION_is_resumable(ss)) /* 1.1.1 */
3583 int len = i2d_SSL_SESSION(ss, NULL);
3584 int dlen = sizeof(dbdata_tls_session) + len;
3585 dbdata_tls_session * dt = store_get(dlen, TRUE);
3586 uschar * s = dt->session;
3587 open_db dbblock, * dbm_file;
3589 DEBUG(D_tls) debug_printf("session is resumable\n");
3590 tlsp->resumption |= RESUME_SERVER_TICKET; /* server gave us a ticket */
3592 dt->verify_override = tlsp->verify_override;
3593 dt->ocsp = tlsp->ocsp;
3594 (void) i2d_SSL_SESSION(ss, &s); /* s gets bumped to end */
3596 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3598 const uschar * key = cbinfo->host->address;
3599 dbfn_delete(dbm_file, key);
3600 dbfn_write(dbm_file, key, dt, dlen);
3601 dbfn_close(dbm_file);
3602 DEBUG(D_tls) debug_printf("wrote session (len %u) to db\n",
3611 tls_client_ctx_resume_prehandshake(
3612 exim_openssl_client_tls_ctx * exim_client_ctx, tls_support * tlsp,
3613 smtp_transport_options_block * ob, host_item * host)
3615 /* Should the client request a session resumption ticket? */
3616 if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
3618 tlsp->host_resumable = TRUE;
3620 SSL_CTX_set_session_cache_mode(exim_client_ctx->ctx,
3621 SSL_SESS_CACHE_CLIENT
3622 | SSL_SESS_CACHE_NO_INTERNAL | SSL_SESS_CACHE_NO_AUTO_CLEAR);
3623 SSL_CTX_sess_set_new_cb(exim_client_ctx->ctx, tls_save_session_cb);
3628 tls_client_ssl_resume_prehandshake(SSL * ssl, tls_support * tlsp,
3629 host_item * host, uschar ** errstr)
3631 if (tlsp->host_resumable)
3634 debug_printf("tls_resumption_hosts overrides openssl_options, enabling tickets\n");
3635 SSL_clear_options(ssl, SSL_OP_NO_TICKET);
3637 tls_exdata_idx = SSL_get_ex_new_index(0, 0, 0, 0, 0);
3638 if (!SSL_set_ex_data(ssl, tls_exdata_idx, client_static_state))
3640 tls_error(US"set ex_data", host, NULL, errstr);
3643 debug_printf("tls_exdata_idx %d cbinfo %p\n", tls_exdata_idx, client_static_state);
3646 tlsp->resumption = RESUME_SUPPORTED;
3647 /* Pick up a previous session, saved on an old ticket */
3648 tls_retrieve_session(tlsp, ssl, host->address);
3653 tls_client_resume_posthandshake(exim_openssl_client_tls_ctx * exim_client_ctx,
3656 if (SSL_session_reused(exim_client_ctx->ssl))
3658 DEBUG(D_tls) debug_printf("The session was reused\n");
3659 tlsp->resumption |= RESUME_USED;
3662 #endif /* !DISABLE_TLS_RESUME */
3665 #ifdef EXIM_HAVE_ALPN
3666 /* Expand and convert an Exim list to an ALPN list. False return for fail.
3667 NULL plist return for silent no-ALPN.
3671 tls_alpn_plist(const uschar * tls_alpn, const uschar ** plist, unsigned * plen,
3676 if (!expand_check(tls_alpn, US"tls_alpn", &exp_alpn, errstr))
3681 DEBUG(D_tls) debug_printf("Setting TLS ALPN forced to fail, not sending\n");
3686 /* The server implementation only accepts exactly one protocol name
3687 but it's little extra code complexity in the client. */
3689 const uschar * list = exp_alpn;
3690 uschar * p = store_get(Ustrlen(exp_alpn), is_tainted(exp_alpn)), * s, * t;
3694 for (t = p; s = string_nextinlist(&list, &sep, NULL, 0); t += len)
3696 *t++ = len = (uschar) Ustrlen(s);
3699 *plist = (*plen = t - p) ? p : NULL;
3703 #endif /* EXIM_HAVE_ALPN */
3706 /*************************************************
3707 * Start a TLS session in a client *
3708 *************************************************/
3710 /* Called from the smtp transport after STARTTLS has been accepted.
3713 cctx connection context
3714 conn_args connection details
3715 cookie datum for randomness; can be NULL
3716 tlsp record details of TLS channel configuration here; must be non-NULL
3717 errstr error string pointer
3719 Returns: TRUE for success with TLS session context set in connection context,
3724 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
3725 void * cookie, tls_support * tlsp, uschar ** errstr)
3727 host_item * host = conn_args->host; /* for msgs and option-tests */
3728 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
3729 smtp_transport_options_block * ob = tb
3730 ? (smtp_transport_options_block *)tb->options_block
3731 : &smtp_transport_option_defaults;
3732 exim_openssl_client_tls_ctx * exim_client_ctx;
3733 uschar * expciphers;
3735 static uschar peerdn[256];
3737 #ifndef DISABLE_OCSP
3738 BOOL request_ocsp = FALSE;
3739 BOOL require_ocsp = FALSE;
3743 store_pool = POOL_PERM;
3744 exim_client_ctx = store_get(sizeof(exim_openssl_client_tls_ctx), FALSE);
3745 exim_client_ctx->corked = NULL;
3749 tlsp->tlsa_usage = 0;
3752 #ifndef DISABLE_OCSP
3754 # ifdef SUPPORT_DANE
3755 /*XXX this should be moved to caller, to be common across gnutls/openssl */
3756 if ( conn_args->dane
3757 && ob->hosts_request_ocsp[0] == '*'
3758 && ob->hosts_request_ocsp[1] == '\0'
3761 /* Unchanged from default. Use a safer one under DANE */
3762 request_ocsp = TRUE;
3763 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
3764 " {= {4}{$tls_out_tlsa_usage}} } "
3770 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK))
3771 request_ocsp = TRUE;
3773 # ifdef SUPPORT_DANE
3777 verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3781 rc = tls_init(host, ob,
3782 #ifndef DISABLE_OCSP
3783 (void *)(long)request_ocsp,
3785 cookie, &client_static_state, tlsp, errstr);
3786 if (rc != OK) return FALSE;
3788 exim_client_ctx->ctx = client_static_state->lib_state.lib_ctx;
3790 tlsp->certificate_verified = FALSE;
3791 client_verify_callback_called = FALSE;
3795 if (conn_args->dane)
3797 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
3798 other failures should be treated as problems. */
3799 if (ob->dane_require_tls_ciphers &&
3800 !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
3801 &expciphers, errstr))
3803 if (expciphers && *expciphers == '\0')
3808 !expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
3809 &expciphers, errstr))
3812 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
3813 are separated by underscores. So that I can use either form in my tests, and
3814 also for general convenience, we turn underscores into hyphens here. */
3818 uschar *s = expciphers;
3819 while (*s) { if (*s == '_') *s = '-'; s++; }
3820 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
3821 if (!SSL_CTX_set_cipher_list(exim_client_ctx->ctx, CS expciphers))
3823 tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
3829 if (conn_args->dane)
3831 SSL_CTX_set_verify(exim_client_ctx->ctx,
3832 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
3833 verify_callback_client_dane);
3835 if (!DANESSL_library_init())
3837 tls_error(US"library init", host, NULL, errstr);
3840 if (DANESSL_CTX_init(exim_client_ctx->ctx) <= 0)
3842 tls_error(US"context init", host, NULL, errstr);
3850 if (tls_client_basic_ctx_init(exim_client_ctx->ctx, host, ob,
3851 client_static_state, errstr) != OK)
3854 #ifndef DISABLE_TLS_RESUME
3855 tls_client_ctx_resume_prehandshake(exim_client_ctx, tlsp, ob, host);
3859 if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx)))
3861 tls_error(US"SSL_new", host, NULL, errstr);
3864 SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx));
3866 SSL_set_fd(exim_client_ctx->ssl, cctx->sock);
3867 SSL_set_connect_state(exim_client_ctx->ssl);
3871 if (!expand_check(ob->tls_sni, US"tls_sni", &tlsp->sni, errstr))
3875 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
3877 else if (!Ustrlen(tlsp->sni))
3881 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
3882 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tlsp->sni);
3883 SSL_set_tlsext_host_name(exim_client_ctx->ssl, tlsp->sni);
3885 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
3892 #ifdef EXIM_HAVE_ALPN
3894 const uschar * plist;
3897 if (!tls_alpn_plist(ob->tls_alpn, &plist, &plen, errstr))
3900 if (SSL_set_alpn_protos(exim_client_ctx->ssl, plist, plen) != 0)
3902 tls_error(US"alpn init", host, NULL, errstr);
3906 DEBUG(D_tls) debug_printf("Setting TLS ALPN '%s'\n", ob->tls_alpn);
3909 log_write(0, LOG_MAIN, "ALPN unusable with this OpenSSL library version; ignoring \"%s\"\n",
3914 if (conn_args->dane)
3915 if (dane_tlsa_load(exim_client_ctx->ssl, host, &conn_args->tlsa_dnsa, errstr) != OK)
3919 #ifndef DISABLE_OCSP
3920 /* Request certificate status at connection-time. If the server
3921 does OCSP stapling we will get the callback (set in tls_init()) */
3922 # ifdef SUPPORT_DANE
3926 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
3927 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
3929 { /* Re-eval now $tls_out_tlsa_usage is populated. If
3930 this means we avoid the OCSP request, we wasted the setup
3931 cost in tls_init(). */
3932 require_ocsp = verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
3933 request_ocsp = require_ocsp
3934 || verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3941 SSL_set_tlsext_status_type(exim_client_ctx->ssl, TLSEXT_STATUSTYPE_ocsp);
3942 client_static_state->u_ocsp.client.verify_required = require_ocsp;
3943 tlsp->ocsp = OCSP_NOT_RESP;
3947 #ifndef DISABLE_TLS_RESUME
3948 if (!tls_client_ssl_resume_prehandshake(exim_client_ctx->ssl, tlsp, host,
3953 #ifndef DISABLE_EVENT
3954 client_static_state->event_action = tb ? tb->event_action : NULL;
3957 /* There doesn't seem to be a built-in timeout on connection. */
3959 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
3960 sigalrm_seen = FALSE;
3961 ALARM(ob->command_timeout);
3962 rc = SSL_connect(exim_client_ctx->ssl);
3966 if (conn_args->dane)
3967 DANESSL_cleanup(exim_client_ctx->ssl);
3972 tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, errstr);
3978 debug_printf("SSL_connect succeeded\n");
3979 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3981 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
3982 SSL_SESSION_print_keylog(bp, SSL_get_session(exim_client_ctx->ssl));
3988 #ifndef DISABLE_TLS_RESUME
3989 tls_client_resume_posthandshake(exim_client_ctx, tlsp);
3992 #ifdef EXIM_HAVE_ALPN
3993 if (ob->tls_alpn) /* We requested. See what was negotiated. */
3995 const uschar * name;
3998 SSL_get0_alpn_selected(exim_client_ctx->ssl, &name, &len);
4000 { DEBUG(D_tls) debug_printf("ALPN negotiated %u: '%.*s'\n", len, (int)*name, name+1); }
4001 else if (verify_check_given_host(CUSS &ob->hosts_require_alpn, host) == OK)
4003 /* Would like to send a relevant fatal Alert, but OpenSSL has no API */
4004 tls_error(US"handshake", host, US"ALPN required but not negotiated", errstr);
4010 #ifdef SSL_get_extms_support
4011 tlsp->ext_master_secret = SSL_get_extms_support(exim_client_ctx->ssl) == 1;
4013 peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn));
4015 tlsp->ver = tlsver_name(exim_client_ctx->ssl);
4016 tlsp->cipher = construct_cipher_name(exim_client_ctx->ssl, tlsp->ver, &tlsp->bits);
4017 tlsp->cipher_stdname = cipher_stdname_ssl(exim_client_ctx->ssl);
4019 /* Record the certificate we presented */
4021 X509 * crt = SSL_get_certificate(exim_client_ctx->ssl);
4022 tlsp->ourcert = crt ? X509_dup(crt) : NULL;
4025 /*XXX will this work with continued-TLS? */
4026 /* Channel-binding info for authenticators */
4029 size_t len = SSL_get_finished(exim_client_ctx->ssl, &c, 0);
4030 int old_pool = store_pool;
4032 SSL_get_finished(exim_client_ctx->ssl, s = store_get((int)len, TRUE), len);
4033 store_pool = POOL_PERM;
4034 tlsp->channelbinding = b64encode_taint(CUS s, (int)len, TRUE);
4035 store_pool = old_pool;
4036 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage %p %p\n", tlsp->channelbinding, tlsp);
4039 tlsp->active.sock = cctx->sock;
4040 tlsp->active.tls_ctx = exim_client_ctx;
4041 cctx->tls_ctx = exim_client_ctx;
4050 tls_refill(unsigned lim)
4052 SSL * ssl = state_server.lib_state.lib_ssl;
4056 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
4057 ssl_xfer_buffer, ssl_xfer_buffer_size);
4060 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
4061 inbytes = SSL_read(ssl, CS ssl_xfer_buffer,
4062 MIN(ssl_xfer_buffer_size, lim));
4063 error = SSL_get_error(ssl, inbytes);
4064 if (smtp_receive_timeout > 0) ALARM_CLR(0);
4066 if (had_command_timeout) /* set by signal handler */
4067 smtp_command_timeout_exit(); /* does not return */
4068 if (had_command_sigterm)
4069 smtp_command_sigterm_exit();
4070 if (had_data_timeout)
4071 smtp_data_timeout_exit();
4072 if (had_data_sigint)
4073 smtp_data_sigint_exit();
4075 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
4076 closed down, not that the socket itself has been closed down. Revert to
4077 non-SSL handling. */
4081 case SSL_ERROR_NONE:
4084 case SSL_ERROR_ZERO_RETURN:
4085 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
4087 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
4090 tls_close(NULL, TLS_NO_SHUTDOWN);
4093 /* Handle genuine errors */
4095 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4096 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
4097 ssl_xfer_error = TRUE;
4101 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
4102 DEBUG(D_tls) if (error == SSL_ERROR_SYSCALL)
4103 debug_printf(" - syscall %s\n", strerror(errno));
4104 ssl_xfer_error = TRUE;
4108 #ifndef DISABLE_DKIM
4109 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
4111 ssl_xfer_buffer_hwm = inbytes;
4112 ssl_xfer_buffer_lwm = 0;
4117 /*************************************************
4118 * TLS version of getc *
4119 *************************************************/
4121 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
4122 it refills the buffer via the SSL reading function.
4124 Arguments: lim Maximum amount to read/buffer
4125 Returns: the next character or EOF
4127 Only used by the server-side TLS.
4131 tls_getc(unsigned lim)
4133 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
4134 if (!tls_refill(lim))
4135 return ssl_xfer_error ? EOF : smtp_getc(lim);
4137 /* Something in the buffer; return next uschar */
4139 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
4145 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm;
4149 tls_getbuf(unsigned * len)
4154 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
4155 if (!tls_refill(*len))
4157 if (!ssl_xfer_error) return smtp_getbuf(len);
4162 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
4164 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
4165 ssl_xfer_buffer_lwm += size;
4172 tls_get_cache(unsigned lim)
4174 #ifndef DISABLE_DKIM
4175 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
4176 debug_printf("tls_get_cache\n");
4180 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
4186 tls_could_getc(void)
4188 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm
4189 || SSL_pending(state_server.lib_state.lib_ssl) > 0;
4193 /*************************************************
4194 * Read bytes from TLS channel *
4195 *************************************************/
4199 ct_ctx client context pointer, or NULL for the one global server context
4203 Returns: the number of bytes read
4204 -1 after a failed read, including EOF
4206 Only used by the client-side TLS.
4210 tls_read(void * ct_ctx, uschar *buff, size_t len)
4212 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
4213 : state_server.lib_state.lib_ssl;
4217 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
4218 buff, (unsigned int)len);
4221 inbytes = SSL_read(ssl, CS buff, len);
4222 error = SSL_get_error(ssl, inbytes);
4224 if (error == SSL_ERROR_ZERO_RETURN)
4226 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
4229 else if (error != SSL_ERROR_NONE)
4239 /*************************************************
4240 * Write bytes down TLS channel *
4241 *************************************************/
4245 ct_ctx client context pointer, or NULL for the one global server context
4248 more further data expected soon
4250 Returns: the number of bytes after a successful write,
4251 -1 after a failed write
4253 Used by both server-side and client-side TLS. Calling with len zero and more unset
4254 will flush buffered writes; buff can be null for this case.
4258 tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
4261 int outbytes, error;
4263 ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
4264 : state_server.lib_state.lib_ssl;
4265 static gstring * server_corked = NULL;
4266 gstring ** corkedp = ct_ctx
4267 ? &((exim_openssl_client_tls_ctx *)ct_ctx)->corked : &server_corked;
4268 gstring * corked = *corkedp;
4270 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
4271 buff, (unsigned long)len, more ? ", more" : "");
4273 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
4274 "more" is notified. This hack is only ok if small amounts are involved AND only
4275 one stream does it, in one context (i.e. no store reset). Currently it is used
4276 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only.
4277 We support callouts done by the server process by using a separate client
4278 context for the stashed information. */
4279 /* + if PIPE_COMMAND, banner & ehlo-resp for smmtp-on-connect. Suspect there's
4280 a store reset there, so use POOL_PERM. */
4281 /* + if CHUNKING, cmds EHLO,MAIL,RCPT(s),BDAT */
4285 if (!len) buff = US &error; /* dummy just so that string_catn is ok */
4287 int save_pool = store_pool;
4288 store_pool = POOL_PERM;
4290 corked = string_catn(corked, buff, len);
4292 store_pool = save_pool;
4299 buff = CUS corked->s;
4304 for (int left = len; left > 0;)
4306 DEBUG(D_tls) debug_printf("SSL_write(%p, %p, %d)\n", ssl, buff, left);
4308 outbytes = SSL_write(ssl, CS buff, left);
4309 error = SSL_get_error(ssl, outbytes);
4310 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
4313 case SSL_ERROR_NONE: /* the usual case */
4319 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4320 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
4323 case SSL_ERROR_ZERO_RETURN:
4324 log_write(0, LOG_MAIN, "SSL channel closed on write");
4327 case SSL_ERROR_SYSCALL:
4328 if (ct_ctx || errno != ECONNRESET || !f.smtp_in_quit)
4329 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
4330 sender_fullhost ? sender_fullhost : US"<unknown>",
4332 else if (LOGGING(protocol_detail))
4333 log_write(0, LOG_MAIN, "[%s] after QUIT, client reset TCP before"
4334 " SMTP response and TLS close\n", sender_host_address);
4336 DEBUG(D_tls) debug_printf("[%s] SSL_write: after QUIT,"
4337 " client reset TCP before TLS close\n", sender_host_address);
4341 log_write(0, LOG_MAIN, "SSL_write error %d", error);
4352 ct_ctx client TLS context pointer, or NULL for the one global server context
4356 tls_shutdown_wr(void * ct_ctx)
4358 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4359 SSL ** sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4360 int * fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4363 if (*fdp < 0) return; /* TLS was not active */
4365 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
4367 HDEBUG(D_transport|D_tls|D_acl|D_v) debug_printf_indent(" SMTP(TLS shutdown)>>\n");
4368 rc = SSL_shutdown(*sslp);
4369 if (rc < 0) DEBUG(D_tls)
4371 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4372 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4376 /*************************************************
4377 * Close down a TLS session *
4378 *************************************************/
4380 /* This is also called from within a delivery subprocess forked from the
4381 daemon, to shut down the TLS library, without actually doing a shutdown (which
4382 would tamper with the SSL session in the parent process).
4385 ct_ctx client TLS context pointer, or NULL for the one global server context
4386 do_shutdown 0 no data-flush or TLS close-alert
4387 1 if TLS close-alert is to be sent,
4388 2 if also response to be waited for
4392 Used by both server-side and client-side TLS.
4396 tls_close(void * ct_ctx, int do_shutdown)
4398 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4399 SSL ** sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4400 int * fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4402 if (*fdp < 0) return; /* TLS was not active */
4407 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
4408 do_shutdown > 1 ? " (with response-wait)" : "");
4410 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
4412 if ( (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
4416 rc = SSL_shutdown(*sslp); /* wait for response */
4420 if (rc < 0) DEBUG(D_tls)
4422 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4423 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4427 if (!o_ctx) /* server side */
4429 #ifndef DISABLE_OCSP
4430 sk_X509_pop_free(state_server.verify_stack, X509_free);
4431 state_server.verify_stack = NULL;
4434 receive_getc = smtp_getc;
4435 receive_getbuf = smtp_getbuf;
4436 receive_get_cache = smtp_get_cache;
4437 receive_hasc = smtp_hasc;
4438 receive_ungetc = smtp_ungetc;
4439 receive_feof = smtp_feof;
4440 receive_ferror = smtp_ferror;
4441 tls_in.active.tls_ctx = NULL;
4443 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
4454 /*************************************************
4455 * Let tls_require_ciphers be checked at startup *
4456 *************************************************/
4458 /* The tls_require_ciphers option, if set, must be something which the
4461 Returns: NULL on success, or error message
4465 tls_validate_require_cipher(void)
4468 uschar *s, *expciphers, *err;
4472 if (!(tls_require_ciphers && *tls_require_ciphers))
4475 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
4477 return US"failed to expand tls_require_ciphers";
4479 if (!(expciphers && *expciphers))
4482 /* normalisation ripped from above */
4484 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
4488 if (lib_ctx_new(&ctx, NULL, &err) == OK)
4491 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
4493 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
4495 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4496 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
4497 expciphers, ssl_errstring);
4508 /*************************************************
4509 * Report the library versions. *
4510 *************************************************/
4512 /* There have historically been some issues with binary compatibility in
4513 OpenSSL libraries; if Exim (like many other applications) is built against
4514 one version of OpenSSL but the run-time linker picks up another version,
4515 it can result in serious failures, including crashing with a SIGSEGV. So
4516 report the version found by the compiler and the run-time version.
4518 Note: some OS vendors backport security fixes without changing the version
4519 number/string, and the version date remains unchanged. The _build_ date
4520 will change, so we can more usefully assist with version diagnosis by also
4521 reporting the build date.
4523 Arguments: a FILE* to print the results to
4528 tls_version_report(FILE *f)
4530 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
4533 OPENSSL_VERSION_TEXT,
4534 SSLeay_version(SSLEAY_VERSION),
4535 SSLeay_version(SSLEAY_BUILT_ON));
4536 /* third line is 38 characters for the %s and the line is 73 chars long;
4537 the OpenSSL output includes a "built on: " prefix already. */
4543 /*************************************************
4544 * Random number generation *
4545 *************************************************/
4547 /* Pseudo-random number generation. The result is not expected to be
4548 cryptographically strong but not so weak that someone will shoot themselves
4549 in the foot using it as a nonce in input in some email header scheme or
4550 whatever weirdness they'll twist this into. The result should handle fork()
4551 and avoid repeating sequences. OpenSSL handles that for us.
4555 Returns a random number in range [0, max-1]
4559 vaguely_random_number(int max)
4563 static pid_t pidlast = 0;
4565 uschar smallbuf[sizeof(r)];
4571 if (pidnow != pidlast)
4573 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
4574 is unique for each thread", this doesn't apparently apply across processes,
4575 so our own warning from vaguely_random_number_fallback() applies here too.
4576 Fix per PostgreSQL. */
4582 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
4586 gettimeofday(&r.tv, NULL);
4589 RAND_seed(US (&r), sizeof(r));
4591 /* We're after pseudo-random, not random; if we still don't have enough data
4592 in the internal PRNG then our options are limited. We could sleep and hope
4593 for entropy to come along (prayer technique) but if the system is so depleted
4594 in the first place then something is likely to just keep taking it. Instead,
4595 we'll just take whatever little bit of pseudo-random we can still manage to
4598 needed_len = sizeof(r);
4599 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
4600 asked for a number less than 10. */
4601 for (r = max, i = 0; r; ++i)
4607 #ifdef EXIM_HAVE_RAND_PSEUDO
4608 /* We do not care if crypto-strong */
4609 i = RAND_pseudo_bytes(smallbuf, needed_len);
4611 i = RAND_bytes(smallbuf, needed_len);
4617 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
4618 return vaguely_random_number_fallback(max);
4622 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
4625 /* We don't particularly care about weighted results; if someone wants
4626 smooth distribution and cares enough then they should submit a patch then. */
4633 /*************************************************
4634 * OpenSSL option parse *
4635 *************************************************/
4637 /* Parse one option for tls_openssl_options_parse below
4640 name one option name
4641 value place to store a value for it
4642 Returns success or failure in parsing
4648 tls_openssl_one_option_parse(uschar *name, long *value)
4651 int last = exim_openssl_options_size;
4652 while (last > first)
4654 int middle = (first + last)/2;
4655 int c = Ustrcmp(name, exim_openssl_options[middle].name);
4658 *value = exim_openssl_options[middle].value;
4672 /*************************************************
4673 * OpenSSL option parsing logic *
4674 *************************************************/
4676 /* OpenSSL has a number of compatibility options which an administrator might
4677 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
4678 we look like log_selector.
4681 option_spec the administrator-supplied string of options
4682 results ptr to long storage for the options bitmap
4683 Returns success or failure
4687 tls_openssl_options_parse(uschar *option_spec, long *results)
4690 uschar * exp, * end;
4691 BOOL adding, item_parsed;
4693 /* Server: send no (<= TLS1.2) session tickets */
4694 result = SSL_OP_NO_TICKET;
4696 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
4697 from default because it increases BEAST susceptibility. */
4698 #ifdef SSL_OP_NO_SSLv2
4699 result |= SSL_OP_NO_SSLv2;
4701 #ifdef SSL_OP_NO_SSLv3
4702 result |= SSL_OP_NO_SSLv3;
4704 #ifdef SSL_OP_SINGLE_DH_USE
4705 result |= SSL_OP_SINGLE_DH_USE;
4707 #ifdef SSL_OP_NO_RENEGOTIATION
4708 result |= SSL_OP_NO_RENEGOTIATION;
4717 if (!expand_check(option_spec, US"openssl_options", &exp, &end))
4720 for (uschar * s = exp; *s; /**/)
4722 while (isspace(*s)) ++s;
4725 if (*s != '+' && *s != '-')
4727 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
4728 "+ or - expected but found \"%s\"\n", s);
4731 adding = *s++ == '+';
4732 for (end = s; *end && !isspace(*end); ) end++;
4733 item_parsed = tls_openssl_one_option_parse(string_copyn(s, end-s), &item);
4736 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
4739 DEBUG(D_tls) debug_printf("openssl option, %s %08lx: %08lx (%s)\n",
4740 adding ? "adding to " : "removing from", result, item, s);
4752 #endif /*!MACRO_PREDEF*/
4755 /* End of tls-openssl.c */