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.
555 sctx The current SSL CTX (inbound or outbound)
556 dhparam DH parameter file or fixed parameter identity string
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, uschar ** errstr)
566 #if OPENSSL_VERSION_NUMBER < 0x30000000L
575 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded, errstr))
578 if (!dhexpanded || !*dhexpanded)
579 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
580 else if (dhexpanded[0] == '/')
582 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
584 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
585 NULL, US strerror(errno), errstr);
591 if (Ustrcmp(dhexpanded, "none") == 0)
593 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
597 if (!(pem = std_dh_prime_named(dhexpanded)))
599 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
600 NULL, US strerror(errno), errstr);
603 bio = BIO_new_mem_buf(CS pem, -1);
607 #if OPENSSL_VERSION_NUMBER < 0x30000000L
608 dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)
610 pkey = PEM_read_bio_Parameters_ex(bio, NULL, NULL, NULL)
615 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
620 /* note: our default limit of 2236 is not a multiple of 8; the limit comes from
621 an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with 2236.
622 But older OpenSSL can only report in bytes (octets), not bits. If someone wants
623 to dance at the edge, then they can raise the limit or use current libraries. */
625 #if OPENSSL_VERSION_NUMBER < 0x30000000L
626 # ifdef EXIM_HAVE_OPENSSL_DH_BITS
627 /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022
628 This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */
629 dh_bitsize = DH_bits(dh);
631 dh_bitsize = 8 * DH_size(dh);
634 dh_bitsize = EVP_PKEY_get_bits(pkey);
637 /* Even if it is larger, we silently return success rather than cause things to
638 fail out, so that a too-large DH will not knock out all TLS; it's a debatable
639 choice. Likewise for a failing attempt to set one. */
641 if (dh_bitsize <= tls_dh_max_bits)
644 #if OPENSSL_VERSION_NUMBER < 0x30000000L
645 SSL_CTX_set_tmp_dh(sctx, dh)
647 SSL_CTX_set0_tmp_dh_pkey(sctx, pkey)
651 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
652 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (D-H param setting '%s'): %s",
653 dhexpanded ? dhexpanded : US"default", ssl_errstring);
654 #if OPENSSL_VERSION_NUMBER >= 0x30000000L
655 /* EVP_PKEY_free(pkey); crashes */
660 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
661 dhexpanded ? dhexpanded : US"default", dh_bitsize);
665 debug_printf("dhparams '%s' %d bits, is > tls_dh_max_bits limit of %d\n",
666 dhexpanded ? dhexpanded : US"default", dh_bitsize, tls_dh_max_bits);
668 #if OPENSSL_VERSION_NUMBER < 0x30000000L
671 /* The EVP_PKEY ownership stays with the ctx; do not free it */
680 /*************************************************
681 * Initialize for ECDH *
682 *************************************************/
684 /* Load parameters for ECDH encryption. Server only.
686 For now, we stick to NIST P-256 because: it's simple and easy to configure;
687 it avoids any patent issues that might bite redistributors; despite events in
688 the news and concerns over curve choices, we're not cryptographers, we're not
689 pretending to be, and this is "good enough" to be better than no support,
690 protecting against most adversaries. Given another year or two, there might
691 be sufficient clarity about a "right" way forward to let us make an informed
692 decision, instead of a knee-jerk reaction.
694 Longer-term, we should look at supporting both various named curves and
695 external files generated with "openssl ecparam", much as we do for init_dh().
696 We should also support "none" as a value, to explicitly avoid initialisation.
701 sctx The current SSL CTX (inbound or outbound)
702 errstr error string pointer
704 Returns: TRUE if OK (nothing to set up, or setup worked)
708 init_ecdh(SSL_CTX * sctx, uschar ** errstr)
710 #ifdef OPENSSL_NO_ECDH
718 # ifndef EXIM_HAVE_ECDH
720 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
724 if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve, errstr))
726 if (!exp_curve || !*exp_curve)
729 /* "auto" needs to be handled carefully.
730 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
731 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
732 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
733 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
734 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
736 if (Ustrcmp(exp_curve, "auto") == 0)
738 #if OPENSSL_VERSION_NUMBER < 0x10002000L
739 DEBUG(D_tls) debug_printf(
740 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
741 exp_curve = US"prime256v1";
743 # if defined SSL_CTRL_SET_ECDH_AUTO
744 DEBUG(D_tls) debug_printf(
745 "ECDH OpenSSL 1.0.2+: temp key parameter settings: autoselection\n");
746 SSL_CTX_set_ecdh_auto(sctx, 1);
749 DEBUG(D_tls) debug_printf(
750 "ECDH OpenSSL 1.1.0+: temp key parameter settings: default selection\n");
756 DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve);
757 if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef
758 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
759 && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef
763 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve),
768 # if OPENSSL_VERSION_NUMBER < 0x30000000L
771 if (!(ecdh = EC_KEY_new_by_curve_name(nid)))
773 tls_error(US"Unable to create ec curve", NULL, NULL, errstr);
777 /* The "tmp" in the name here refers to setting a temporary key
778 not to the stability of the interface. */
780 if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0))
781 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), NULL, NULL, errstr);
783 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve);
787 #else /* v 3.0.0 + */
789 if ((rv = SSL_CTX_set1_groups(sctx, &nid, 1)) == 0)
790 tls_error(string_sprintf("Error enabling '%s' group", exp_curve), NULL, NULL, errstr);
792 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' group\n", exp_curve);
798 # endif /*EXIM_HAVE_ECDH*/
799 #endif /*OPENSSL_NO_ECDH*/
804 /*************************************************
805 * Expand key and cert file specs *
806 *************************************************/
808 #if OPENSSL_VERSION_NUMBER < 0x30000000L
811 s SSL connection (not used)
815 Returns: pointer to generated key
819 rsa_callback(SSL *s, int export, int keylength)
822 #ifdef EXIM_HAVE_RSA_GENKEY_EX
823 BIGNUM *bn = BN_new();
826 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
828 # ifdef EXIM_HAVE_RSA_GENKEY_EX
829 if ( !BN_set_word(bn, (unsigned long)RSA_F4)
830 || !(rsa_key = RSA_new())
831 || !RSA_generate_key_ex(rsa_key, keylength, bn, NULL)
834 if (!(rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL)))
838 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
839 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
845 #endif /* pre-3.0.0 */
849 /* Create and install a selfsigned certificate, for use in server mode */
850 /*XXX we could arrange to call this during prelo for a null tls_certificate option.
851 The normal cache inval + relo will suffice.
852 Just need a timer for inval. */
855 tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr)
862 DEBUG(D_tls) debug_printf("TLS: generating selfsigned server cert\n");
863 where = US"allocating pkey";
864 if (!(pkey = EVP_PKEY_new()))
867 where = US"allocating cert";
868 if (!(x509 = X509_new()))
871 where = US"generating pkey";
872 #if OPENSSL_VERSION_NUMBER < 0x30000000L
875 if (!(rsa = rsa_callback(NULL, 0, 2048)))
878 where = US"assigning pkey";
879 if (!EVP_PKEY_assign_RSA(pkey, rsa))
883 pkey = EVP_RSA_gen(2048);
886 X509_set_version(x509, 2); /* N+1 - version 3 */
887 ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
888 X509_gmtime_adj(X509_get_notBefore(x509), 0);
889 X509_gmtime_adj(X509_get_notAfter(x509), (long)2 * 60 * 60); /* 2 hour */
890 X509_set_pubkey(x509, pkey);
892 name = X509_get_subject_name(x509);
893 X509_NAME_add_entry_by_txt(name, "C",
894 MBSTRING_ASC, CUS "UK", -1, -1, 0);
895 X509_NAME_add_entry_by_txt(name, "O",
896 MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0);
897 X509_NAME_add_entry_by_txt(name, "CN",
898 MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0);
899 X509_set_issuer_name(x509, name);
901 where = US"signing cert";
902 if (!X509_sign(x509, pkey, EVP_md5()))
905 where = US"installing selfsign cert";
906 if (!SSL_CTX_use_certificate(sctx, x509))
909 where = US"installing selfsign key";
910 if (!SSL_CTX_use_PrivateKey(sctx, pkey))
916 (void) tls_error(where, NULL, NULL, errstr);
917 if (x509) X509_free(x509);
918 if (pkey) EVP_PKEY_free(pkey);
928 /*************************************************
929 * Information callback *
930 *************************************************/
932 /* The SSL library functions call this from time to time to indicate what they
933 are doing. We copy the string to the debugging output when TLS debugging has
945 info_callback(SSL *s, int where, int ret)
951 if (where & SSL_ST_CONNECT)
952 str = US"SSL_connect";
953 else if (where & SSL_ST_ACCEPT)
954 str = US"SSL_accept";
956 str = US"SSL info (undefined)";
958 if (where & SSL_CB_LOOP)
959 debug_printf("%s: %s\n", str, SSL_state_string_long(s));
960 else if (where & SSL_CB_ALERT)
961 debug_printf("SSL3 alert %s:%s:%s\n",
962 str = where & SSL_CB_READ ? US"read" : US"write",
963 SSL_alert_type_string_long(ret), SSL_alert_desc_string_long(ret));
964 else if (where & SSL_CB_EXIT)
967 debug_printf("%s: failed in %s\n", str, SSL_state_string_long(s));
969 debug_printf("%s: error in %s\n", str, SSL_state_string_long(s));
971 else if (where & SSL_CB_HANDSHAKE_START)
972 debug_printf("%s: hshake start: %s\n", str, SSL_state_string_long(s));
973 else if (where & SSL_CB_HANDSHAKE_DONE)
974 debug_printf("%s: hshake done: %s\n", str, SSL_state_string_long(s));
978 #ifdef OPENSSL_HAVE_KEYLOG_CB
980 keylog_callback(const SSL *ssl, const char *line)
984 DEBUG(D_tls) debug_printf("%.200s\n", line);
985 if (!(filename = getenv("SSLKEYLOGFILE"))) return;
986 if (!(fp = fopen(filename, "a"))) return;
987 fprintf(fp, "%s\n", line);
996 #ifndef DISABLE_EVENT
998 verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
999 BOOL *calledp, const BOOL *optionalp, const uschar * what)
1005 ev = tlsp == &tls_out ? client_static_state->event_action : event_action;
1008 DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth);
1009 old_cert = tlsp->peercert;
1010 tlsp->peercert = X509_dup(cert);
1011 /* NB we do not bother setting peerdn */
1012 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
1014 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
1015 "depth=%d cert=%s: %s",
1016 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1017 what, depth, dn, yield);
1021 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
1022 return 1; /* reject (leaving peercert set) */
1024 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
1025 "(host in tls_try_verify_hosts)\n");
1026 tlsp->verify_override = TRUE;
1028 X509_free(tlsp->peercert);
1029 tlsp->peercert = old_cert;
1035 /*************************************************
1036 * Callback for verification *
1037 *************************************************/
1039 /* The SSL library does certificate verification if set up to do so. This
1040 callback has the current yes/no state is in "state". If verification succeeded,
1041 we set the certificate-verified flag. If verification failed, what happens
1042 depends on whether the client is required to present a verifiable certificate
1045 If verification is optional, we change the state to yes, but still log the
1046 verification error. For some reason (it really would help to have proper
1047 documentation of OpenSSL), this callback function then gets called again, this
1048 time with state = 1. We must take care not to set the private verified flag on
1049 the second time through.
1051 Note: this function is not called if the client fails to present a certificate
1052 when asked. We get here only if a certificate has been received. Handling of
1053 optional verification for this case is done when requesting SSL to verify, by
1054 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
1056 May be called multiple times for different issues with a certificate, even
1057 for a given "depth" in the certificate chain.
1060 preverify_ok current yes/no state as 1/0
1061 x509ctx certificate information.
1062 tlsp per-direction (client vs. server) support data
1063 calledp has-been-called flag
1064 optionalp verification-is-optional flag
1066 Returns: 0 if verification should fail, otherwise 1
1070 verify_callback(int preverify_ok, X509_STORE_CTX * x509ctx,
1071 tls_support * tlsp, BOOL * calledp, BOOL * optionalp)
1073 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
1074 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
1077 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
1079 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
1080 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1081 tlsp == &tls_out ? deliver_host_address : sender_host_address);
1084 dn[sizeof(dn)-1] = '\0';
1086 tlsp->verify_override = FALSE;
1087 if (preverify_ok == 0)
1089 uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])",
1090 *verify_mode, sender_host_address)
1092 log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
1093 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1095 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn);
1099 if (!tlsp->peercert)
1100 tlsp->peercert = X509_dup(cert); /* record failing cert */
1101 return 0; /* reject */
1103 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
1104 "tls_try_verify_hosts)\n");
1105 tlsp->verify_override = TRUE;
1108 else if (depth != 0)
1110 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
1111 #ifndef DISABLE_OCSP
1112 if (tlsp == &tls_out && client_static_state->u_ocsp.client.verify_store)
1113 { /* client, wanting stapling */
1114 /* Add the server cert's signing chain as the one
1115 for the verification of the OCSP stapled information. */
1117 if (!X509_STORE_add_cert(client_static_state->u_ocsp.client.verify_store,
1120 sk_X509_push(client_static_state->verify_stack, cert);
1123 #ifndef DISABLE_EVENT
1124 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
1125 return 0; /* reject, with peercert set */
1130 const uschar * verify_cert_hostnames;
1132 if ( tlsp == &tls_out
1133 && ((verify_cert_hostnames = client_static_state->verify_cert_hostnames)))
1134 /* client, wanting hostname check */
1137 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
1138 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
1139 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
1141 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
1142 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
1145 const uschar * list = verify_cert_hostnames;
1148 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
1149 if ((rc = X509_check_host(cert, CCS name, 0,
1150 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
1151 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
1156 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1157 tlsp == &tls_out ? deliver_host_address : sender_host_address);
1164 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
1167 uschar * extra = verify_mode
1168 ? string_sprintf(" (during %c-verify for [%s])",
1169 *verify_mode, sender_host_address)
1171 log_write(0, LOG_MAIN,
1172 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
1173 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1174 extra, dn, verify_cert_hostnames);
1178 if (!tlsp->peercert)
1179 tlsp->peercert = X509_dup(cert); /* record failing cert */
1180 return 0; /* reject */
1182 DEBUG(D_tls) debug_printf("SSL verify name failure overridden (host in "
1183 "tls_try_verify_hosts)\n");
1184 tlsp->verify_override = TRUE;
1188 #ifndef DISABLE_EVENT
1189 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
1190 return 0; /* reject, with peercert set */
1193 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
1194 *calledp ? "" : " authenticated", dn);
1198 return 1; /* accept, at least for this level */
1202 verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
1204 return verify_callback(preverify_ok, x509ctx, &tls_out,
1205 &client_verify_callback_called, &client_verify_optional);
1209 verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
1211 return verify_callback(preverify_ok, x509ctx, &tls_in,
1212 &server_verify_callback_called, &server_verify_optional);
1218 /* This gets called *by* the dane library verify callback, which interposes
1222 verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
1224 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
1226 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
1227 #ifndef DISABLE_EVENT
1228 BOOL dummy_called, optional = FALSE;
1231 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
1233 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
1234 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1235 deliver_host_address);
1238 dn[sizeof(dn)-1] = '\0';
1240 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
1241 preverify_ok ? "ok":"BAD", depth, dn);
1243 #ifndef DISABLE_EVENT
1244 if (verify_event(&tls_out, cert, depth, dn,
1245 &dummy_called, &optional, US"DANE"))
1246 return 0; /* reject, with peercert set */
1249 if (preverify_ok == 1)
1251 tls_out.dane_verified = TRUE;
1252 #ifndef DISABLE_OCSP
1253 if (client_static_state->u_ocsp.client.verify_store)
1254 { /* client, wanting stapling */
1255 /* Add the server cert's signing chain as the one
1256 for the verification of the OCSP stapled information. */
1258 if (!X509_STORE_add_cert(client_static_state->u_ocsp.client.verify_store,
1261 sk_X509_push(client_static_state->verify_stack, cert);
1267 int err = X509_STORE_CTX_get_error(x509ctx);
1269 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
1270 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
1273 return preverify_ok;
1276 #endif /*SUPPORT_DANE*/
1279 #ifndef DISABLE_OCSP
1280 /*************************************************
1281 * Load OCSP information into state *
1282 *************************************************/
1283 /* Called to load the server OCSP response from the given file into memory, once
1284 caller has determined this is needed. Checks validity. Debugs a message
1287 ASSUMES: single response, for single cert.
1290 state various parts of session state
1291 filename the filename putatively holding an OCSP response
1292 is_pem file is PEM format; otherwise is DER
1296 ocsp_load_response(exim_openssl_state_st * state, const uschar * filename,
1300 OCSP_RESPONSE * resp;
1301 OCSP_BASICRESP * basic_response;
1302 OCSP_SINGLERESP * single_response;
1303 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
1304 STACK_OF(X509) * sk;
1305 unsigned long verify_flags;
1306 int status, reason, i;
1309 debug_printf("tls_ocsp_file (%s) '%s'\n", is_pem ? "PEM" : "DER", filename);
1311 if (!filename || !*filename) return;
1314 if (!(bio = BIO_new_file(CS filename, "rb")))
1316 log_write(0, LOG_MAIN|LOG_PANIC,
1317 "Failed to open OCSP response file \"%s\": %.100s",
1318 filename, ERR_reason_error_string(ERR_get_error()));
1324 uschar * data, * freep;
1327 if (!PEM_read_bio(bio, &dummy, &dummy, &data, &len))
1329 log_write(0, LOG_MAIN|LOG_PANIC, "Failed to read PEM file \"%s\": %.100s",
1330 filename, ERR_reason_error_string(ERR_get_error()));
1334 resp = d2i_OCSP_RESPONSE(NULL, CUSS &data, len);
1335 OPENSSL_free(freep);
1338 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
1343 log_write(0, LOG_MAIN|LOG_PANIC, "Error reading OCSP response from \"%s\": %s",
1344 filename, ERR_reason_error_string(ERR_get_error()));
1348 if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
1350 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
1351 OCSP_response_status_str(status), status);
1357 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1358 OCSP_RESPONSE_print(bp, resp, 0); /* extreme debug: stapling content */
1363 if (!(basic_response = OCSP_response_get1_basic(resp)))
1366 debug_printf("OCSP response parse error: unable to extract basic response.\n");
1370 sk = state->verify_stack;
1371 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
1373 /* May need to expose ability to adjust those flags?
1374 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
1375 OCSP_TRUSTOTHER OCSP_NOINTERN */
1377 /* This does a full verify on the OCSP proof before we load it for serving
1378 up; possibly overkill - just date-checks might be nice enough.
1380 OCSP_basic_verify takes a "store" arg, but does not
1381 use it for the chain verification, which is all we do
1382 when OCSP_NOVERIFY is set. The content from the wire
1383 "basic_response" and a cert-stack "sk" are all that is used.
1385 We have a stack, loaded in setup_certs() if tls_verify_certificates
1386 was a file (not a directory, or "system"). It is unfortunate we
1387 cannot used the connection context store, as that would neatly
1388 handle the "system" case too, but there seems to be no library
1389 function for getting a stack from a store.
1390 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
1391 We do not free the stack since it could be needed a second time for
1394 Separately we might try to replace using OCSP_basic_verify() - which seems to not
1395 be a public interface into the OpenSSL library (there's no manual entry) -
1396 But what with? We also use OCSP_basic_verify in the client stapling callback.
1397 And there we NEED it; we must verify that status... unless the
1398 library does it for us anyway? */
1400 if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0)
1404 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1405 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
1410 /* Here's the simplifying assumption: there's only one response, for the
1411 one certificate we use, and nothing for anything else in a chain. If this
1412 proves false, we need to extract a cert id from our issued cert
1413 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
1414 right cert in the stack and then calls OCSP_single_get0_status()).
1416 I'm hoping to avoid reworking a bunch more of how we handle state here.
1418 XXX that will change when we add support for (TLS1.3) whole-chain stapling
1421 if (!(single_response = OCSP_resp_get0(basic_response, 0)))
1424 debug_printf("Unable to get first response from OCSP basic response.\n");
1428 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
1429 if (status != V_OCSP_CERTSTATUS_GOOD)
1431 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
1432 OCSP_cert_status_str(status), status,
1433 OCSP_crl_reason_str(reason), reason);
1437 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1439 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
1444 /* Add the resp to the list used by tls_server_stapling_cb() */
1446 ocsp_resplist ** op = &state->u_ocsp.server.olist, * oentry;
1447 while (oentry = *op)
1449 *op = oentry = store_get(sizeof(ocsp_resplist), FALSE);
1450 oentry->next = NULL;
1451 oentry->resp = resp;
1456 if (f.running_in_test_harness)
1458 extern char ** environ;
1459 if (environ) for (uschar ** p = USS environ; *p; p++)
1460 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1462 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
1463 goto supply_response;
1471 ocsp_free_response_list(exim_openssl_state_st * cbinfo)
1473 for (ocsp_resplist * olist = cbinfo->u_ocsp.server.olist; olist;
1474 olist = olist->next)
1475 OCSP_RESPONSE_free(olist->resp);
1476 cbinfo->u_ocsp.server.olist = NULL;
1478 #endif /*!DISABLE_OCSP*/
1485 tls_add_certfile(SSL_CTX * sctx, exim_openssl_state_st * cbinfo, uschar * file,
1488 DEBUG(D_tls) debug_printf("tls_certificate file '%s'\n", file);
1489 if (!SSL_CTX_use_certificate_chain_file(sctx, CS file))
1490 return tls_error(string_sprintf(
1491 "SSL_CTX_use_certificate_chain_file file=%s", file),
1492 cbinfo->host, NULL, errstr);
1497 tls_add_pkeyfile(SSL_CTX * sctx, exim_openssl_state_st * cbinfo, uschar * file,
1500 DEBUG(D_tls) debug_printf("tls_privatekey file '%s'\n", file);
1501 if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM))
1502 return tls_error(string_sprintf(
1503 "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr);
1510 /* Called once during tls_init and possibly again during TLS setup, for a
1511 new context, if Server Name Indication was used and tls_sni was seen in
1512 the certificate string.
1515 sctx the SSL_CTX* to update
1516 state various parts of session state
1517 errstr error string pointer
1519 Returns: OK/DEFER/FAIL
1523 tls_expand_session_files(SSL_CTX * sctx, exim_openssl_state_st * state,
1528 if (!state->certificate)
1530 if (!state->is_server) /* client */
1533 if (tls_install_selfsign(sctx, errstr) != OK)
1540 if ( !reexpand_tls_files_for_sni
1541 && ( Ustrstr(state->certificate, US"tls_sni")
1542 || Ustrstr(state->certificate, US"tls_in_sni")
1543 || Ustrstr(state->certificate, US"tls_out_sni")
1545 reexpand_tls_files_for_sni = TRUE;
1547 if (!expand_check(state->certificate, US"tls_certificate", &expanded, errstr))
1551 if (state->is_server)
1553 const uschar * file_list = expanded;
1556 #ifndef DISABLE_OCSP
1557 const uschar * olist = state->u_ocsp.server.file;
1560 BOOL fmt_pem = FALSE;
1563 if (!expand_check(olist, US"tls_ocsp_file", USS &olist, errstr))
1565 if (olist && !*olist)
1568 if ( state->u_ocsp.server.file_expanded && olist
1569 && (Ustrcmp(olist, state->u_ocsp.server.file_expanded) == 0))
1571 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
1576 ocsp_free_response_list(state);
1577 state->u_ocsp.server.file_expanded = olist;
1581 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1583 if ((err = tls_add_certfile(sctx, state, file, errstr)))
1586 #ifndef DISABLE_OCSP
1588 if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1590 if (Ustrncmp(ofile, US"PEM ", 4) == 0)
1595 else if (Ustrncmp(ofile, US"DER ", 4) == 0)
1600 ocsp_load_response(state, ofile, fmt_pem);
1603 DEBUG(D_tls) debug_printf("ran out of ocsp file list\n");
1607 else /* would there ever be a need for multiple client certs? */
1608 if ((err = tls_add_certfile(sctx, state, expanded, errstr)))
1611 if ( state->privatekey
1612 && !expand_check(state->privatekey, US"tls_privatekey", &expanded, errstr))
1615 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1616 of the expansion is an empty string, ignore it also, and assume the private
1617 key is in the same file as the certificate. */
1619 if (expanded && *expanded)
1620 if (state->is_server)
1622 const uschar * file_list = expanded;
1626 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1627 if ((err = tls_add_pkeyfile(sctx, state, file, errstr)))
1630 else /* would there ever be a need for multiple client certs? */
1631 if ((err = tls_add_pkeyfile(sctx, state, expanded, errstr)))
1641 /**************************************************
1642 * One-time init credentials for server and client *
1643 **************************************************/
1646 server_load_ciphers(SSL_CTX * ctx, exim_openssl_state_st * state,
1647 uschar * ciphers, uschar ** errstr)
1649 for (uschar * s = ciphers; *s; s++ ) if (*s == '_') *s = '-';
1650 DEBUG(D_tls) debug_printf("required ciphers: %s\n", ciphers);
1651 if (!SSL_CTX_set_cipher_list(ctx, CS ciphers))
1652 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
1653 state->server_cipher_list = ciphers;
1660 lib_ctx_new(SSL_CTX ** ctxp, host_item * host, uschar ** errstr)
1663 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1664 if (!(ctx = SSL_CTX_new(host ? TLS_client_method() : TLS_server_method())))
1666 if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
1668 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
1670 /* Set up the information callback, which outputs if debugging is at a suitable
1675 SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
1676 #if defined(EXIM_HAVE_OPESSL_TRACE) && !defined(OPENSSL_NO_SSL_TRACE)
1677 /* this needs a debug build of OpenSSL */
1678 SSL_CTX_set_msg_callback(ctx, (void (*)())SSL_trace);
1680 #ifdef OPENSSL_HAVE_KEYLOG_CB
1681 SSL_CTX_set_keylog_callback(ctx, (void (*)())keylog_callback);
1685 /* Automatically re-try reads/writes after renegotiation. */
1686 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
1693 tls_server_creds_init(void)
1696 uschar * dummy_errstr;
1697 unsigned lifetime = 0;
1701 state_server.lib_state = null_tls_preload;
1703 if (lib_ctx_new(&ctx, NULL, &dummy_errstr) != OK)
1705 state_server.lib_state.lib_ctx = ctx;
1707 /* Preload DH params and EC curve */
1709 if (opt_unset_or_noexpand(tls_dhparam))
1711 DEBUG(D_tls) debug_printf("TLS: preloading DH params for server\n");
1712 if (init_dh(ctx, tls_dhparam, &dummy_errstr))
1713 state_server.lib_state.dh = TRUE;
1716 DEBUG(D_tls) debug_printf("TLS: not preloading DH params for server\n");
1717 if (opt_unset_or_noexpand(tls_eccurve))
1719 DEBUG(D_tls) debug_printf("TLS: preloading ECDH curve for server\n");
1720 if (init_ecdh(ctx, &dummy_errstr))
1721 state_server.lib_state.ecdh = TRUE;
1724 DEBUG(D_tls) debug_printf("TLS: not preloading ECDH curve for server\n");
1726 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1727 /* If we can, preload the server-side cert, key and ocsp */
1729 if ( opt_set_and_noexpand(tls_certificate)
1730 # ifndef DISABLE_OCSP
1731 && opt_unset_or_noexpand(tls_ocsp_file)
1733 && opt_unset_or_noexpand(tls_privatekey))
1735 /* Set watches on the filenames. The implementation does de-duplication
1736 so we can just blindly do them all. */
1738 if ( tls_set_watch(tls_certificate, TRUE)
1739 # ifndef DISABLE_OCSP
1740 && tls_set_watch(tls_ocsp_file, TRUE)
1742 && tls_set_watch(tls_privatekey, TRUE))
1744 state_server.certificate = tls_certificate;
1745 state_server.privatekey = tls_privatekey;
1746 #ifndef DISABLE_OCSP
1747 state_server.u_ocsp.server.file = tls_ocsp_file;
1750 DEBUG(D_tls) debug_printf("TLS: preloading server certs\n");
1751 if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
1752 state_server.lib_state.conn_certs = TRUE;
1755 else if ( !tls_certificate && !tls_privatekey
1756 # ifndef DISABLE_OCSP
1760 { /* Generate & preload a selfsigned cert. No files to watch. */
1761 if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
1763 state_server.lib_state.conn_certs = TRUE;
1764 lifetime = f.running_in_test_harness ? 2 : 60 * 60; /* 1 hour */
1768 DEBUG(D_tls) debug_printf("TLS: not preloading server certs\n");
1771 /* If we can, preload the Authorities for checking client certs against.
1772 Actual choice to do verify is made (tls_{,try_}verify_hosts)
1773 at TLS conn startup */
1775 if ( opt_set_and_noexpand(tls_verify_certificates)
1776 && opt_unset_or_noexpand(tls_crl))
1778 /* Watch the default dir also as they are always included */
1780 if ( tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
1781 && tls_set_watch(tls_verify_certificates, FALSE)
1782 && tls_set_watch(tls_crl, FALSE))
1784 DEBUG(D_tls) debug_printf("TLS: preloading CA bundle for server\n");
1786 if (setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, &dummy_errstr)
1788 state_server.lib_state.cabundle = TRUE;
1792 DEBUG(D_tls) debug_printf("TLS: not preloading CA bundle for server\n");
1793 #endif /* EXIM_HAVE_INOTIFY */
1796 /* If we can, preload the ciphers control string */
1798 if (opt_set_and_noexpand(tls_require_ciphers))
1800 DEBUG(D_tls) debug_printf("TLS: preloading cipher list for server\n");
1801 if (server_load_ciphers(ctx, &state_server, tls_require_ciphers,
1802 &dummy_errstr) == OK)
1803 state_server.lib_state.pri_string = TRUE;
1806 DEBUG(D_tls) debug_printf("TLS: not preloading cipher list for server\n");
1813 /* Preload whatever creds are static, onto a transport. The client can then
1814 just copy the pointer as it starts up.
1815 Called from the daemon after a cache-invalidate with watch set; called from
1816 a queue-run startup with watch clear. */
1819 tls_client_creds_init(transport_instance * t, BOOL watch)
1821 smtp_transport_options_block * ob = t->options_block;
1822 exim_openssl_state_st tpt_dummy_state;
1823 host_item * dummy_host = (host_item *)1;
1824 uschar * dummy_errstr;
1829 ob->tls_preload = null_tls_preload;
1830 if (lib_ctx_new(&ctx, dummy_host, &dummy_errstr) != OK)
1832 ob->tls_preload.lib_ctx = ctx;
1834 tpt_dummy_state.lib_state = ob->tls_preload;
1836 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1837 if ( opt_set_and_noexpand(ob->tls_certificate)
1838 && opt_unset_or_noexpand(ob->tls_privatekey))
1841 || ( tls_set_watch(ob->tls_certificate, FALSE)
1842 && tls_set_watch(ob->tls_privatekey, FALSE)
1845 uschar * pkey = ob->tls_privatekey;
1848 debug_printf("TLS: preloading client certs for transport '%s'\n",t->name);
1850 if ( tls_add_certfile(ctx, &tpt_dummy_state, ob->tls_certificate,
1852 && tls_add_pkeyfile(ctx, &tpt_dummy_state,
1853 pkey ? pkey : ob->tls_certificate,
1856 ob->tls_preload.conn_certs = TRUE;
1861 debug_printf("TLS: not preloading client certs, for transport '%s'\n", t->name);
1864 if ( opt_set_and_noexpand(ob->tls_verify_certificates)
1865 && opt_unset_or_noexpand(ob->tls_crl))
1868 || tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
1869 && tls_set_watch(ob->tls_verify_certificates, FALSE)
1870 && tls_set_watch(ob->tls_crl, FALSE)
1874 debug_printf("TLS: preloading CA bundle for transport '%s'\n", t->name);
1876 if (setup_certs(ctx, ob->tls_verify_certificates,
1877 ob->tls_crl, dummy_host, &dummy_errstr) == OK)
1878 ob->tls_preload.cabundle = TRUE;
1883 debug_printf("TLS: not preloading CA bundle, for transport '%s'\n", t->name);
1885 #endif /*EXIM_HAVE_INOTIFY*/
1889 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1890 /* Invalidate the creds cached, by dropping the current ones.
1891 Call when we notice one of the source files has changed. */
1894 tls_server_creds_invalidate(void)
1896 SSL_CTX_free(state_server.lib_state.lib_ctx);
1897 state_server.lib_state = null_tls_preload;
1902 tls_client_creds_invalidate(transport_instance * t)
1904 smtp_transport_options_block * ob = t->options_block;
1905 SSL_CTX_free(ob->tls_preload.lib_ctx);
1906 ob->tls_preload = null_tls_preload;
1912 tls_server_creds_invalidate(void)
1916 tls_client_creds_invalidate(transport_instance * t)
1919 #endif /*EXIM_HAVE_INOTIFY*/
1923 #ifndef DISABLE_OCSP
1925 x509_store_dump_cert_s_names(X509_STORE * store)
1927 STACK_OF(X509_OBJECT) * roots= store->objs;
1928 static uschar name[256];
1930 for (int i= 0; i < sk_X509_OBJECT_num(roots); i++)
1932 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
1933 if(tmp_obj->type == X509_LU_X509)
1935 X509_NAME * sn = X509_get_subject_name(tmp_obj->data.x509);
1936 if (X509_NAME_oneline(sn, CS name, sizeof(name)))
1938 name[sizeof(name)-1] = '\0';
1939 debug_printf(" %s\n", name);
1948 #ifndef DISABLE_TLS_RESUME
1949 /* Manage the keysets used for encrypting the session tickets, on the server. */
1951 typedef struct { /* Session ticket encryption key */
1954 const EVP_CIPHER * aes_cipher;
1955 uschar aes_key[32]; /* size needed depends on cipher. aes_128 implies 128/8 = 16? */
1956 const EVP_MD * hmac_hash;
1957 uschar hmac_key[16];
1962 static exim_stek exim_tk; /* current key */
1963 static exim_stek exim_tk_old; /* previous key */
1968 time_t t = time(NULL);
1970 if (exim_tk.name[0])
1972 if (exim_tk.renew >= t) return;
1973 exim_tk_old = exim_tk;
1976 if (f.running_in_test_harness) ssl_session_timeout = 6;
1978 DEBUG(D_tls) debug_printf("OpenSSL: %s STEK\n", exim_tk.name[0] ? "rotating" : "creating");
1979 if (RAND_bytes(exim_tk.aes_key, sizeof(exim_tk.aes_key)) <= 0) return;
1980 if (RAND_bytes(exim_tk.hmac_key, sizeof(exim_tk.hmac_key)) <= 0) return;
1981 if (RAND_bytes(exim_tk.name+1, sizeof(exim_tk.name)-1) <= 0) return;
1983 exim_tk.name[0] = 'E';
1984 exim_tk.aes_cipher = EVP_aes_256_cbc();
1985 exim_tk.hmac_hash = EVP_sha256();
1986 exim_tk.expire = t + ssl_session_timeout;
1987 exim_tk.renew = t + ssl_session_timeout/2;
1993 if (!exim_tk.name[0]) return NULL;
1998 tk_find(const uschar * name)
2000 return memcmp(name, exim_tk.name, sizeof(exim_tk.name)) == 0 ? &exim_tk
2001 : memcmp(name, exim_tk_old.name, sizeof(exim_tk_old.name)) == 0 ? &exim_tk_old
2005 /* Callback for session tickets, on server */
2007 ticket_key_callback(SSL * ssl, uschar key_name[16],
2008 uschar * iv, EVP_CIPHER_CTX * c_ctx, HMAC_CTX * hctx, int enc)
2010 tls_support * tlsp = state_server.tlsp;
2015 DEBUG(D_tls) debug_printf("ticket_key_callback: create new session\n");
2016 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
2018 if (RAND_bytes(iv, EVP_MAX_IV_LENGTH) <= 0)
2019 return -1; /* insufficient random */
2021 if (!(key = tk_current())) /* current key doesn't exist or isn't valid */
2022 return 0; /* key couldn't be created */
2023 memcpy(key_name, key->name, 16);
2024 DEBUG(D_tls) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - time(NULL));
2026 /*XXX will want these dependent on the ssl session strength */
2027 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
2028 key->hmac_hash, NULL);
2029 EVP_EncryptInit_ex(c_ctx, key->aes_cipher, NULL, key->aes_key, iv);
2031 DEBUG(D_tls) debug_printf("ticket created\n");
2036 time_t now = time(NULL);
2038 DEBUG(D_tls) debug_printf("ticket_key_callback: retrieve session\n");
2039 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
2041 if (!(key = tk_find(key_name)) || key->expire < now)
2045 debug_printf("ticket not usable (%s)\n", key ? "expired" : "not found");
2046 if (key) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - now);
2051 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
2052 key->hmac_hash, NULL);
2053 EVP_DecryptInit_ex(c_ctx, key->aes_cipher, NULL, key->aes_key, iv);
2055 DEBUG(D_tls) debug_printf("ticket usable, STEK expire " TIME_T_FMT "\n", key->expire - now);
2057 /* The ticket lifetime and renewal are the same as the STEK lifetime and
2058 renewal, which is overenthusiastic. A factor of, say, 3x longer STEK would
2059 be better. To do that we'd have to encode ticket lifetime in the name as
2060 we don't yet see the restored session. Could check posthandshake for TLS1.3
2061 and trigger a new ticket then, but cannot do that for TLS1.2 */
2062 return key->renew < now ? 2 : 1;
2070 setup_cert_verify(SSL_CTX * ctx, BOOL optional,
2071 int (*cert_vfy_cb)(int, X509_STORE_CTX *))
2073 /* If verification is optional, don't fail if no certificate */
2075 SSL_CTX_set_verify(ctx,
2076 SSL_VERIFY_PEER | (optional ? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
2081 /*************************************************
2082 * Callback to handle SNI *
2083 *************************************************/
2085 /* Called when acting as server during the TLS session setup if a Server Name
2086 Indication extension was sent by the client.
2088 API documentation is OpenSSL s_server.c implementation.
2091 s SSL* of the current session
2092 ad unknown (part of OpenSSL API) (unused)
2093 arg Callback of "our" registered data
2095 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
2097 XXX might need to change to using ClientHello callback,
2098 per https://www.openssl.org/docs/manmaster/man3/SSL_client_hello_cb_fn.html
2101 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2103 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
2105 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
2106 exim_openssl_state_st *state = (exim_openssl_state_st *) arg;
2108 int old_pool = store_pool;
2109 uschar * dummy_errstr;
2112 return SSL_TLSEXT_ERR_OK;
2114 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
2115 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
2117 /* Make the extension value available for expansion */
2118 store_pool = POOL_PERM;
2119 tls_in.sni = string_copy_taint(US servername, TRUE);
2120 store_pool = old_pool;
2122 if (!reexpand_tls_files_for_sni)
2123 return SSL_TLSEXT_ERR_OK;
2125 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
2126 not confident that memcpy wouldn't break some internal reference counting.
2127 Especially since there's a references struct member, which would be off. */
2129 if (lib_ctx_new(&server_sni, NULL, &dummy_errstr) != OK)
2132 /* Not sure how many of these are actually needed, since SSL object
2133 already exists. Might even need this selfsame callback, for reneg? */
2136 SSL_CTX * ctx = state_server.lib_state.lib_ctx;
2137 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(ctx));
2138 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(ctx));
2139 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(ctx));
2140 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(ctx));
2141 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
2142 SSL_CTX_set_tlsext_servername_arg(server_sni, state);
2145 if ( !init_dh(server_sni, state->dhparam, &dummy_errstr)
2146 || !init_ecdh(server_sni, &dummy_errstr)
2150 if ( state->server_cipher_list
2151 && !SSL_CTX_set_cipher_list(server_sni, CS state->server_cipher_list))
2154 #ifndef DISABLE_OCSP
2155 if (state->u_ocsp.server.file)
2157 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
2158 SSL_CTX_set_tlsext_status_arg(server_sni, state);
2164 if ( !expand_check(tls_verify_certificates, US"tls_verify_certificates",
2165 &expcerts, &dummy_errstr)
2166 || (rc = setup_certs(server_sni, expcerts, tls_crl, NULL,
2167 &dummy_errstr)) != OK)
2170 if (expcerts && *expcerts)
2171 setup_cert_verify(server_sni, FALSE, verify_callback_server);
2174 /* do this after setup_certs, because this can require the certs for verifying
2175 OCSP information. */
2176 if ((rc = tls_expand_session_files(server_sni, state, &dummy_errstr)) != OK)
2179 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
2180 SSL_set_SSL_CTX(s, server_sni);
2181 return SSL_TLSEXT_ERR_OK;
2183 bad: return SSL_TLSEXT_ERR_ALERT_FATAL;
2185 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
2190 #ifdef EXIM_HAVE_ALPN
2191 /*************************************************
2192 * Callback to handle ALPN *
2193 *************************************************/
2195 /* Called on server if tls_alpn nonblank after expansion,
2196 when client offers ALPN, after the SNI callback.
2197 If set and not matching the list then we dump the connection */
2200 tls_server_alpn_cb(SSL *ssl, const uschar ** out, uschar * outlen,
2201 const uschar * in, unsigned int inlen, void * arg)
2203 server_seen_alpn = TRUE;
2206 debug_printf("Received TLS ALPN offer:");
2207 for (int pos = 0, siz; pos < inlen; pos += siz+1)
2210 if (pos + 1 + siz > inlen) siz = inlen - pos - 1;
2211 debug_printf(" '%.*s'", siz, in + pos + 1);
2213 debug_printf(". Our list: '%s'\n", tls_alpn);
2216 /* Look for an acceptable ALPN */
2218 if ( inlen > 1 /* at least one name */
2219 && in[0]+1 == inlen /* filling the vector, so exactly one name */
2222 const uschar * list = tls_alpn;
2224 for (uschar * name; name = string_nextinlist(&list, &sep, NULL, 0); )
2225 if (Ustrncmp(in+1, name, in[0]) == 0)
2227 *out = in+1; /* we checked for exactly one, so can just point to it */
2229 return SSL_TLSEXT_ERR_OK; /* use ALPN */
2233 /* More than one name from clilent, or name did not match our list. */
2235 /* This will be fatal to the TLS conn; would be nice to kill TCP also.
2236 Maybe as an option in future; for now leave control to the config (must-tls). */
2238 DEBUG(D_tls) debug_printf("TLS ALPN rejected\n");
2239 return SSL_TLSEXT_ERR_ALERT_FATAL;
2241 #endif /* EXIM_HAVE_ALPN */
2245 #ifndef DISABLE_OCSP
2247 /*************************************************
2248 * Callback to handle OCSP Stapling *
2249 *************************************************/
2251 /* Called when acting as server during the TLS session setup if the client
2252 requests OCSP information with a Certificate Status Request.
2254 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
2260 tls_server_stapling_cb(SSL *s, void *arg)
2262 const exim_openssl_state_st * state = arg;
2263 ocsp_resplist * olist = state->u_ocsp.server.olist;
2264 uschar * response_der; /*XXX blob */
2265 int response_der_len;
2268 debug_printf("Received TLS status request (OCSP stapling); %s response list\n",
2269 olist ? "have" : "lack");
2271 tls_in.ocsp = OCSP_NOT_RESP;
2273 return SSL_TLSEXT_ERR_NOACK;
2275 #ifdef EXIM_HAVE_OPESSL_GET0_SERIAL
2277 const X509 * cert_sent = SSL_get_certificate(s);
2278 const ASN1_INTEGER * cert_serial = X509_get0_serialNumber(cert_sent);
2279 const BIGNUM * cert_bn = ASN1_INTEGER_to_BN(cert_serial, NULL);
2281 for (; olist; olist = olist->next)
2283 OCSP_BASICRESP * bs = OCSP_response_get1_basic(olist->resp);
2284 const OCSP_SINGLERESP * single = OCSP_resp_get0(bs, 0);
2285 const OCSP_CERTID * cid = OCSP_SINGLERESP_get0_id(single);
2286 ASN1_INTEGER * res_cert_serial;
2287 const BIGNUM * resp_bn;
2288 ASN1_OCTET_STRING * res_cert_iNameHash;
2291 (void) OCSP_id_get0_info(&res_cert_iNameHash, NULL, NULL, &res_cert_serial,
2292 (OCSP_CERTID *) cid);
2293 resp_bn = ASN1_INTEGER_to_BN(res_cert_serial, NULL);
2297 debug_printf("cert serial: %s\n", BN_bn2hex(cert_bn));
2298 debug_printf("resp serial: %s\n", BN_bn2hex(resp_bn));
2301 if (BN_cmp(cert_bn, resp_bn) == 0)
2303 DEBUG(D_tls) debug_printf("matched serial for ocsp\n");
2305 /*XXX TODO: check the rest of the list for duplicate matches.
2306 If any, need to also check the Issuer Name hash.
2307 Without this, we will provide the wrong status in the case of
2312 DEBUG(D_tls) debug_printf("not match serial for ocsp\n");
2316 DEBUG(D_tls) debug_printf("failed to find match for ocsp\n");
2317 return SSL_TLSEXT_ERR_NOACK;
2323 DEBUG(D_tls) debug_printf("OpenSSL version too early to support multi-leaf OCSP\n");
2324 return SSL_TLSEXT_ERR_NOACK;
2328 /*XXX could we do the i2d earlier, rather than during the callback? */
2329 response_der = NULL;
2330 response_der_len = i2d_OCSP_RESPONSE(olist->resp, &response_der);
2331 if (response_der_len <= 0)
2332 return SSL_TLSEXT_ERR_NOACK;
2334 SSL_set_tlsext_status_ocsp_resp(state_server.lib_state.lib_ssl,
2335 response_der, response_der_len);
2336 tls_in.ocsp = OCSP_VFIED;
2337 return SSL_TLSEXT_ERR_OK;
2342 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
2344 BIO_printf(bp, "\t%s: ", str);
2345 ASN1_GENERALIZEDTIME_print(bp, time);
2350 tls_client_stapling_cb(SSL *s, void *arg)
2352 exim_openssl_state_st * cbinfo = arg;
2353 const unsigned char * p;
2355 OCSP_RESPONSE * rsp;
2356 OCSP_BASICRESP * bs;
2359 DEBUG(D_tls) debug_printf("Received TLS status callback (OCSP stapling):\n");
2360 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
2363 /* Expect this when we requested ocsp but got none */
2364 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
2365 log_write(0, LOG_MAIN, "Required TLS certificate status not received");
2367 DEBUG(D_tls) debug_printf(" null\n");
2368 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2371 if (!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
2373 tls_out.ocsp = OCSP_FAILED; /*XXX should use tlsp-> to permit concurrent outbound */
2374 if (LOGGING(tls_cipher))
2375 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
2377 DEBUG(D_tls) debug_printf(" parse error\n");
2381 if (!(bs = OCSP_response_get1_basic(rsp)))
2383 tls_out.ocsp = OCSP_FAILED;
2384 if (LOGGING(tls_cipher))
2385 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
2387 DEBUG(D_tls) debug_printf(" error parsing response\n");
2388 OCSP_RESPONSE_free(rsp);
2392 /* We'd check the nonce here if we'd put one in the request. */
2393 /* However that would defeat cacheability on the server so we don't. */
2395 /* This section of code reworked from OpenSSL apps source;
2396 The OpenSSL Project retains copyright:
2397 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
2401 #ifndef EXIM_HAVE_OCSP_RESP_COUNT
2402 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
2405 DEBUG(D_tls) bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
2407 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
2409 /* Use the chain that verified the server cert to verify the stapled info */
2410 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
2412 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
2413 cbinfo->u_ocsp.client.verify_store, OCSP_NOEXPLICIT)) <= 0)
2414 if (ERR_peek_error())
2416 tls_out.ocsp = OCSP_FAILED;
2417 if (LOGGING(tls_cipher)) log_write(0, LOG_MAIN,
2418 "Received TLS cert status response, itself unverifiable: %s",
2419 ERR_reason_error_string(ERR_peek_error()));
2420 BIO_printf(bp, "OCSP response verify failure\n");
2421 ERR_print_errors(bp);
2422 OCSP_RESPONSE_print(bp, rsp, 0);
2426 DEBUG(D_tls) debug_printf("no explicit trust for OCSP signing"
2427 " in the root CA certificate; ignoring\n");
2429 DEBUG(D_tls) debug_printf("OCSP response well-formed and signed OK\n");
2431 /*XXX So we have a good stapled OCSP status. How do we know
2432 it is for the cert of interest? OpenSSL 1.1.0 has a routine
2433 OCSP_resp_find_status() which matches on a cert id, which presumably
2434 we should use. Making an id needs OCSP_cert_id_new(), which takes
2435 issuerName, issuerKey, serialNumber. Are they all in the cert?
2437 For now, carry on blindly accepting the resp. */
2440 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
2441 OCSP_resp_count(bs) - 1;
2443 sk_OCSP_SINGLERESP_num(sresp) - 1;
2447 OCSP_SINGLERESP * single = OCSP_resp_get0(bs, idx);
2449 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
2451 /*XXX so I can see putting a loop in here to handle a rsp with >1 singleresp
2452 - but what happens with a GnuTLS-style input?
2454 we could do with a debug label for each singleresp
2455 - it has a certID with a serialNumber, but I see no API to get that
2457 status = OCSP_single_get0_status(single, &reason, &rev,
2458 &thisupd, &nextupd);
2460 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
2461 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
2462 if (!OCSP_check_validity(thisupd, nextupd,
2463 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
2465 tls_out.ocsp = OCSP_FAILED;
2466 DEBUG(D_tls) ERR_print_errors(bp);
2467 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
2471 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
2472 OCSP_cert_status_str(status));
2475 case V_OCSP_CERTSTATUS_GOOD:
2476 continue; /* the idx loop */
2477 case V_OCSP_CERTSTATUS_REVOKED:
2478 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
2479 reason != -1 ? "; reason: " : "",
2480 reason != -1 ? OCSP_crl_reason_str(reason) : "");
2481 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
2484 log_write(0, LOG_MAIN,
2485 "Server certificate status unknown, in OCSP stapling");
2493 tls_out.ocsp = OCSP_VFIED;
2497 tls_out.ocsp = OCSP_FAILED;
2498 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2503 OCSP_RESPONSE_free(rsp);
2506 #endif /*!DISABLE_OCSP*/
2509 /*************************************************
2510 * Initialize for TLS *
2511 *************************************************/
2512 /* Called from both server and client code, to do preliminary initialization
2513 of the library. We allocate and return a context structure.
2516 host connected host, if client; NULL if server
2517 ob transport options block, if client; NULL if server
2518 ocsp_file file of stapling info (server); flag for require ocsp (client)
2519 addr address if client; NULL if server (for some randomness)
2520 caller_state place to put pointer to allocated state-struct
2521 errstr error string pointer
2523 Returns: OK/DEFER/FAIL
2527 tls_init(host_item * host, smtp_transport_options_block * ob,
2528 #ifndef DISABLE_OCSP
2531 address_item *addr, exim_openssl_state_st ** caller_state,
2536 exim_openssl_state_st * state;
2539 if (host) /* client */
2541 state = store_malloc(sizeof(exim_openssl_state_st));
2542 memset(state, 0, sizeof(*state));
2543 state->certificate = ob->tls_certificate;
2544 state->privatekey = ob->tls_privatekey;
2545 state->is_server = FALSE;
2546 state->dhparam = NULL;
2547 state->lib_state = ob->tls_preload;
2551 state = &state_server;
2552 state->certificate = tls_certificate;
2553 state->privatekey = tls_privatekey;
2554 state->is_server = TRUE;
2555 state->dhparam = tls_dhparam;
2556 state->lib_state = state_server.lib_state;
2562 if (!state->lib_state.pri_string)
2563 state->server_cipher_list = NULL;
2565 #ifndef DISABLE_EVENT
2566 state->event_action = NULL;
2571 /* It turns out that we need to seed the random number generator this early in
2572 order to get the full complement of ciphers to work. It took me roughly a day
2573 of work to discover this by experiment.
2575 On systems that have /dev/urandom, SSL may automatically seed itself from
2576 there. Otherwise, we have to make something up as best we can. Double check
2579 Although we likely called this before, at daemon startup, this is a chance
2580 to mix in further variable info (time, pid) if needed. */
2582 if (!lib_rand_init(addr))
2583 return tls_error(US"RAND_status", host,
2584 US"unable to seed random number generator", errstr);
2586 /* Apply administrator-supplied work-arounds.
2587 Historically we applied just one requested option,
2588 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
2589 moved to an administrator-controlled list of options to specify and
2590 grandfathered in the first one as the default value for "openssl_options".
2592 No OpenSSL version number checks: the options we accept depend upon the
2593 availability of the option value macros from OpenSSL. */
2596 if (!tls_openssl_options_parse(openssl_options, &init_options))
2597 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
2599 /* Create a context.
2600 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
2601 negotiation in the different methods; as far as I can tell, the only
2602 *_{server,client}_method which allows negotiation is SSLv23, which exists even
2603 when OpenSSL is built without SSLv2 support.
2604 By disabling with openssl_options, we can let admins re-enable with the
2607 if (!(ctx = state->lib_state.lib_ctx))
2609 if ((rc = lib_ctx_new(&ctx, host, errstr)) != OK)
2611 state->lib_state.lib_ctx = ctx;
2614 #ifndef DISABLE_TLS_RESUME
2615 tlsp->resumption = RESUME_SUPPORTED;
2619 #ifndef DISABLE_TLS_RESUME
2620 /* Should the server offer session resumption? */
2621 if (!host && verify_check_host(&tls_resumption_hosts) == OK)
2623 DEBUG(D_tls) debug_printf("tls_resumption_hosts overrides openssl_options\n");
2624 init_options &= ~SSL_OP_NO_TICKET;
2625 tlsp->resumption |= RESUME_SERVER_TICKET; /* server will give ticket on request */
2626 tlsp->host_resumable = TRUE;
2630 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
2631 if (!(SSL_CTX_set_options(ctx, init_options)))
2632 return tls_error(string_sprintf(
2633 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
2636 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
2638 /* We'd like to disable session cache unconditionally, but foolish Outlook
2639 Express clients then give up the first TLS connection and make a second one
2640 (which works). Only when there is an IMAP service on the same machine.
2641 Presumably OE is trying to use the cache for A on B. Leave it enabled for
2642 now, until we work out a decent way of presenting control to the config. It
2643 will never be used because we use a new context every time. */
2645 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
2648 /* Initialize with DH parameters if supplied */
2649 /* Initialize ECDH temp key parameter selection */
2653 if (state->lib_state.dh)
2654 { DEBUG(D_tls) debug_printf("TLS: DH params were preloaded\n"); }
2656 if (!init_dh(ctx, state->dhparam, errstr)) return DEFER;
2658 if (state->lib_state.ecdh)
2659 { DEBUG(D_tls) debug_printf("TLS: ECDH curve was preloaded\n"); }
2661 if (!init_ecdh(ctx, errstr)) return DEFER;
2664 /* Set up certificate and key (and perhaps OCSP info) */
2666 if (state->lib_state.conn_certs)
2669 debug_printf("TLS: %s certs were preloaded\n", host ? "client":"server");
2673 #ifndef DISABLE_OCSP
2676 state->u_ocsp.server.file = ocsp_file;
2677 state->u_ocsp.server.file_expanded = NULL;
2678 state->u_ocsp.server.olist = NULL;
2681 if ((rc = tls_expand_session_files(ctx, state, errstr)) != OK) return rc;
2684 /* If we need to handle SNI or OCSP, do so */
2686 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2687 # ifndef DISABLE_OCSP
2688 if (!(state->verify_stack = sk_X509_new_null()))
2690 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
2695 if (!host) /* server */
2697 # ifndef DISABLE_OCSP
2698 /* We check u_ocsp.server.file, not server.olist, because we care about if
2699 the option exists, not what the current expansion might be, as SNI might
2700 change the certificate and OCSP file in use between now and the time the
2701 callback is invoked. */
2702 if (state->u_ocsp.server.file)
2704 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
2705 SSL_CTX_set_tlsext_status_arg(ctx, state);
2708 /* We always do this, so that $tls_sni is available even if not used in
2710 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
2711 SSL_CTX_set_tlsext_servername_arg(ctx, state);
2713 # ifdef EXIM_HAVE_ALPN
2714 if (tls_alpn && *tls_alpn)
2717 if ( expand_check(tls_alpn, US"tls_alpn", &exp_alpn, errstr)
2718 && *exp_alpn && !isblank(*exp_alpn))
2720 tls_alpn = exp_alpn; /* subprocess so ok to overwrite */
2721 SSL_CTX_set_alpn_select_cb(ctx, tls_server_alpn_cb, state);
2728 # ifndef DISABLE_OCSP
2730 if(ocsp_file) /* wanting stapling */
2732 if (!(state->u_ocsp.client.verify_store = X509_STORE_new()))
2734 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
2737 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
2738 SSL_CTX_set_tlsext_status_arg(ctx, state);
2743 state->verify_cert_hostnames = NULL;
2745 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
2746 /* Set up the RSA callback */
2747 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
2750 /* Finally, set the session cache timeout, and we are done.
2751 The period appears to be also used for (server-generated) session tickets */
2753 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
2754 DEBUG(D_tls) debug_printf("Initialized TLS\n");
2756 *caller_state = state;
2764 /*************************************************
2765 * Get name of cipher in use *
2766 *************************************************/
2769 Argument: pointer to an SSL structure for the connection
2770 pointer to number of bits for cipher
2771 Returns: pointer to allocated string in perm-pool
2775 construct_cipher_name(SSL * ssl, const uschar * ver, int * bits)
2777 int pool = store_pool;
2778 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
2779 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
2780 the accessor functions use const in the prototype. */
2782 const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
2785 SSL_CIPHER_get_bits(c, bits);
2787 store_pool = POOL_PERM;
2788 s = string_sprintf("%s:%s:%u", ver, SSL_CIPHER_get_name(c), *bits);
2790 DEBUG(D_tls) debug_printf("Cipher: %s\n", s);
2795 /* Get IETF-standard name for ciphersuite.
2796 Argument: pointer to an SSL structure for the connection
2797 Returns: pointer to string
2800 static const uschar *
2801 cipher_stdname_ssl(SSL * ssl)
2803 #ifdef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
2804 return CUS SSL_CIPHER_standard_name(SSL_get_current_cipher(ssl));
2806 ushort id = 0xffff & SSL_CIPHER_get_id(SSL_get_current_cipher(ssl));
2807 return cipher_stdname(id >> 8, id & 0xff);
2812 static const uschar *
2813 tlsver_name(SSL * ssl)
2816 int pool = store_pool;
2818 store_pool = POOL_PERM;
2819 s = string_copy(US SSL_get_version(ssl));
2821 if ((p = Ustrchr(s, 'v'))) /* TLSv1.2 -> TLS1.2 */
2822 for (;; p++) if (!(*p = p[1])) break;
2828 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned siz)
2830 /*XXX we might consider a list-of-certs variable for the cert chain.
2831 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
2832 in list-handling functions, also consider the difference between the entire
2833 chain and the elements sent by the peer. */
2835 tlsp->peerdn = NULL;
2837 /* Will have already noted peercert on a verify fail; possibly not the leaf */
2838 if (!tlsp->peercert)
2839 tlsp->peercert = SSL_get_peer_certificate(ssl);
2840 /* Beware anonymous ciphers which lead to server_cert being NULL */
2842 if (!X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, siz))
2843 { DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n"); }
2846 int oldpool = store_pool;
2848 peerdn[siz-1] = '\0'; /* paranoia */
2849 store_pool = POOL_PERM;
2850 tlsp->peerdn = string_copy(peerdn);
2851 store_pool = oldpool;
2853 /* We used to set CV in the cert-verify callbacks (either plain or dane)
2854 but they don't get called on session-resumption. So use the official
2855 interface, which uses the resumed value. Unfortunately this claims verified
2856 when it actually failed but we're in try-verify mode, due to us wanting the
2857 knowlege that it failed so needing to have the callback and forcing a
2858 permissive return. If we don't force it, the TLS startup is failed.
2859 The extra bit of information is set in verify_override in the cb, stashed
2860 for resumption next to the TLS session, and used here. */
2862 if (!tlsp->verify_override)
2863 tlsp->certificate_verified =
2865 tlsp->dane_verified ||
2867 SSL_get_verify_result(ssl) == X509_V_OK;
2875 /*************************************************
2876 * Set up for verifying certificates *
2877 *************************************************/
2879 #ifndef DISABLE_OCSP
2880 /* Load certs from file, return TRUE on success */
2883 chain_from_pem_file(const uschar * file, STACK_OF(X509) ** vp)
2886 STACK_OF(X509) * verify_stack = *vp;
2889 while (sk_X509_num(verify_stack) > 0)
2890 X509_free(sk_X509_pop(verify_stack));
2892 verify_stack = sk_X509_new_null();
2894 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
2895 for (X509 * x; x = PEM_read_bio_X509(bp, NULL, 0, NULL); )
2896 sk_X509_push(verify_stack, x);
2905 /* Called by both client and server startup; on the server possibly
2906 repeated after a Server Name Indication.
2909 sctx SSL_CTX* to initialise
2910 certs certs file, expanded
2911 crl CRL file or NULL
2912 host NULL in a server; the remote host in a client
2913 errstr error string pointer
2915 Returns: OK/DEFER/FAIL
2919 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host,
2922 uschar *expcerts, *expcrl;
2924 if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
2926 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
2928 if (expcerts && *expcerts)
2930 /* Tell the library to use its compiled-in location for the system default
2931 CA bundle. Then add the ones specified in the config, if any. */
2933 if (!SSL_CTX_set_default_verify_paths(sctx))
2934 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
2936 if (Ustrcmp(expcerts, "system") != 0 && Ustrncmp(expcerts, "system,", 7) != 0)
2938 struct stat statbuf;
2940 if (Ustat(expcerts, &statbuf) < 0)
2942 log_write(0, LOG_MAIN|LOG_PANIC,
2943 "failed to stat %s for certificates", expcerts);
2949 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
2950 { file = NULL; dir = expcerts; }
2953 STACK_OF(X509) * verify_stack =
2954 #ifndef DISABLE_OCSP
2955 !host ? state_server.verify_stack :
2958 STACK_OF(X509) ** vp = &verify_stack;
2960 file = expcerts; dir = NULL;
2961 #ifndef DISABLE_OCSP
2962 /* In the server if we will be offering an OCSP proof, load chain from
2963 file for verifying the OCSP proof at load time. */
2965 /*XXX Glitch! The file here is tls_verify_certs: the chain for verifying the client cert.
2966 This is inconsistent with the need to verify the OCSP proof of the server cert.
2969 && statbuf.st_size > 0
2970 && state_server.u_ocsp.server.file
2971 && !chain_from_pem_file(file, vp)
2974 log_write(0, LOG_MAIN|LOG_PANIC,
2975 "failed to load cert chain from %s", file);
2981 /* If a certificate file is empty, the load function fails with an
2982 unhelpful error message. If we skip it, we get the correct behaviour (no
2983 certificates are recognized, but the error message is still misleading (it
2984 says no certificate was supplied). But this is better. */
2986 if ( (!file || statbuf.st_size > 0)
2987 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
2988 return tls_error(US"SSL_CTX_load_verify_locations",
2989 host, NULL, errstr);
2991 /* On the server load the list of CAs for which we will accept certs, for
2992 sending to the client. This is only for the one-file
2993 tls_verify_certificates variant.
2994 If a list isn't loaded into the server, but some verify locations are set,
2995 the server end appears to make a wildcard request for client certs.
2996 Meanwhile, the client library as default behaviour *ignores* the list
2997 we send over the wire - see man SSL_CTX_set_client_cert_cb.
2998 Because of this, and that the dir variant is likely only used for
2999 the public-CA bundle (not for a private CA), not worth fixing. */
3003 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
3004 int i = sk_X509_NAME_num(names);
3006 if (!host) SSL_CTX_set_client_CA_list(sctx, names);
3007 DEBUG(D_tls) debug_printf("Added %d additional certificate authorit%s\n",
3008 i, i>1 ? "ies":"y");
3012 debug_printf("Added dir for additional certificate authorities\n");
3016 /* Handle a certificate revocation list. */
3018 #if OPENSSL_VERSION_NUMBER > 0x00907000L
3020 /* This bit of code is now the version supplied by Lars Mainka. (I have
3021 merely reformatted it into the Exim code style.)
3023 "From here I changed the code to add support for multiple crl's
3024 in pem format in one file or to support hashed directory entries in
3025 pem format instead of a file. This method now uses the library function
3026 X509_STORE_load_locations to add the CRL location to the SSL context.
3027 OpenSSL will then handle the verify against CA certs and CRLs by
3028 itself in the verify callback." */
3030 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
3031 if (expcrl && *expcrl)
3033 struct stat statbufcrl;
3034 if (Ustat(expcrl, &statbufcrl) < 0)
3036 log_write(0, LOG_MAIN|LOG_PANIC,
3037 "failed to stat %s for certificates revocation lists", expcrl);
3042 /* is it a file or directory? */
3044 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
3045 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
3049 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
3055 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
3057 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
3058 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
3060 /* setting the flags to check against the complete crl chain */
3062 X509_STORE_set_flags(cvstore,
3063 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
3067 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
3075 /*************************************************
3076 * Start a TLS session in a server *
3077 *************************************************/
3078 /* This is called when Exim is running as a server, after having received
3079 the STARTTLS command. It must respond to that command, and then negotiate
3083 errstr pointer to error message
3085 Returns: OK on success
3086 DEFER for errors before the start of the negotiation
3087 FAIL for errors during the negotiation; the server can't
3092 tls_server_start(uschar ** errstr)
3095 uschar * expciphers;
3096 exim_openssl_state_st * dummy_statep;
3099 static uschar peerdn[256];
3101 /* Check for previous activation */
3103 if (tls_in.active.sock >= 0)
3105 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
3106 smtp_printf("554 Already in TLS\r\n", FALSE);
3110 /* Initialize the SSL library. If it fails, it will already have logged
3113 rc = tls_init(NULL, NULL,
3114 #ifndef DISABLE_OCSP
3117 NULL, &dummy_statep, &tls_in, errstr);
3118 if (rc != OK) return rc;
3119 ctx = state_server.lib_state.lib_ctx;
3121 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
3122 were historically separated by underscores. So that I can use either form in my
3123 tests, and also for general convenience, we turn underscores into hyphens here.
3125 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
3126 for TLS 1.3 . Since we do not call it at present we get the default list:
3127 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
3130 if (state_server.lib_state.pri_string)
3131 { DEBUG(D_tls) debug_printf("TLS: cipher list was preloaded\n"); }
3134 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
3138 && (rc = server_load_ciphers(ctx, &state_server, expciphers, errstr)) != OK)
3142 /* If this is a host for which certificate verification is mandatory or
3143 optional, set up appropriately. */
3145 tls_in.certificate_verified = FALSE;
3147 tls_in.dane_verified = FALSE;
3149 server_verify_callback_called = FALSE;
3151 if (verify_check_host(&tls_verify_hosts) == OK)
3152 server_verify_optional = FALSE;
3153 else if (verify_check_host(&tls_try_verify_hosts) == OK)
3154 server_verify_optional = TRUE;
3160 if (!expand_check(tls_verify_certificates, US"tls_verify_certificates",
3163 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3165 if (state_server.lib_state.cabundle)
3166 { DEBUG(D_tls) debug_printf("TLS: CA bundle for server was preloaded\n"); }
3168 if ((rc = setup_certs(ctx, expcerts, tls_crl, NULL, errstr)) != OK)
3171 if (expcerts && *expcerts)
3172 setup_cert_verify(ctx, server_verify_optional, verify_callback_server);
3176 #ifndef DISABLE_TLS_RESUME
3177 SSL_CTX_set_tlsext_ticket_key_cb(ctx, ticket_key_callback);
3178 /* despite working, appears to always return failure, so ignoring */
3180 #ifdef OPENSSL_HAVE_NUM_TICKETS
3181 # ifndef DISABLE_TLS_RESUME
3182 SSL_CTX_set_num_tickets(ctx, tls_in.host_resumable ? 1 : 0);
3184 SSL_CTX_set_num_tickets(ctx, 0); /* send no TLS1.3 stateful-tickets */
3189 /* Prepare for new connection */
3191 if (!(ssl = SSL_new(ctx)))
3192 return tls_error(US"SSL_new", NULL, NULL, errstr);
3193 state_server.lib_state.lib_ssl = ssl;
3195 /* Warning: we used to SSL_clear(ssl) here, it was removed.
3197 * With the SSL_clear(), we get strange interoperability bugs with
3198 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
3199 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
3201 * The SSL_clear() call is to let an existing SSL* be reused, typically after
3202 * session shutdown. In this case, we have a brand new object and there's no
3203 * obvious reason to immediately clear it. I'm guessing that this was
3204 * originally added because of incomplete initialisation which the clear fixed,
3205 * in some historic release.
3208 /* Set context and tell client to go ahead, except in the case of TLS startup
3209 on connection, where outputting anything now upsets the clients and tends to
3210 make them disconnect. We need to have an explicit fflush() here, to force out
3211 the response. Other smtp_printf() calls do not need it, because in non-TLS
3212 mode, the fflush() happens when smtp_getc() is called. */
3214 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
3215 if (!tls_in.on_connect)
3217 smtp_printf("220 TLS go ahead\r\n", FALSE);
3221 /* Now negotiate the TLS session. We put our own timer on it, since it seems
3222 that the OpenSSL library doesn't. */
3224 SSL_set_wfd(ssl, fileno(smtp_out));
3225 SSL_set_rfd(ssl, fileno(smtp_in));
3226 SSL_set_accept_state(ssl);
3228 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
3231 sigalrm_seen = FALSE;
3232 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3233 rc = SSL_accept(ssl);
3238 int error = SSL_get_error(ssl, rc);
3241 case SSL_ERROR_NONE:
3244 case SSL_ERROR_ZERO_RETURN:
3245 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3246 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
3248 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
3251 tls_close(NULL, TLS_NO_SHUTDOWN);
3254 /* Handle genuine errors */
3258 int r = ERR_GET_REASON(ERR_peek_error());
3259 if ( r == SSL_R_WRONG_VERSION_NUMBER
3260 #ifdef SSL_R_VERSION_TOO_LOW
3261 || r == SSL_R_VERSION_TOO_LOW
3263 || r == SSL_R_UNKNOWN_PROTOCOL || r == SSL_R_UNSUPPORTED_PROTOCOL)
3264 s = string_sprintf("%s (%s)", s, SSL_get_version(ssl));
3265 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : s, errstr);
3270 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
3271 if (error == SSL_ERROR_SYSCALL)
3275 *errstr = US"SSL_accept: TCP connection closed by peer";
3278 DEBUG(D_tls) debug_printf(" - syscall %s\n", strerror(errno));
3280 (void) tls_error(US"SSL_accept", NULL,
3281 sigalrm_seen ? US"timed out"
3282 : ERR_peek_error() ? NULL : string_sprintf("ret %d", error),
3288 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
3289 ERR_clear_error(); /* Even success can leave errors in the stack. Seen with
3290 anon-authentication ciphersuite negotiated. */
3292 #ifndef DISABLE_TLS_RESUME
3293 if (SSL_session_reused(ssl))
3295 tls_in.resumption |= RESUME_USED;
3296 DEBUG(D_tls) debug_printf("Session reused\n");
3300 #ifdef EXIM_HAVE_ALPN
3301 /* If require-alpn, check server_seen_alpn here. Else abort TLS */
3302 if (!tls_alpn || !*tls_alpn)
3303 { DEBUG(D_tls) debug_printf("TLS: was not watching for ALPN\n"); }
3304 else if (!server_seen_alpn)
3305 if (verify_check_host(&hosts_require_alpn) == OK)
3307 /* We'd like to send a definitive Alert but OpenSSL provides no facility */
3309 tls_error(US"handshake", NULL, US"ALPN required but not negotiated", errstr);
3313 { DEBUG(D_tls) debug_printf("TLS: no ALPN presented in handshake\n"); }
3316 const uschar * name;
3318 SSL_get0_alpn_selected(ssl, &name, &len);
3320 debug_printf("ALPN negotiated: '%.*s'\n", (int)*name, name+1);
3322 debug_printf("ALPN: no protocol negotiated\n");
3327 /* TLS has been set up. Record data for the connection,
3328 adjust the input functions to read via TLS, and initialize things. */
3330 #ifdef SSL_get_extms_support
3331 tls_in.ext_master_secret = SSL_get_extms_support(ssl) == 1;
3333 peer_cert(ssl, &tls_in, peerdn, sizeof(peerdn));
3335 tls_in.ver = tlsver_name(ssl);
3336 tls_in.cipher = construct_cipher_name(ssl, tls_in.ver, &tls_in.bits);
3337 tls_in.cipher_stdname = cipher_stdname_ssl(ssl);
3342 if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)))
3343 debug_printf("Shared ciphers: %s\n", buf);
3345 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3347 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
3348 SSL_SESSION_print_keylog(bp, SSL_get_session(ssl));
3353 #ifdef EXIM_HAVE_SESSION_TICKET
3355 SSL_SESSION * ss = SSL_get_session(ssl);
3356 if (SSL_SESSION_has_ticket(ss)) /* 1.1.0 */
3357 debug_printf("The session has a ticket, life %lu seconds\n",
3358 SSL_SESSION_get_ticket_lifetime_hint(ss));
3363 /* Record the certificate we presented */
3365 X509 * crt = SSL_get_certificate(ssl);
3366 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
3369 /* Channel-binding info for authenticators
3370 See description in https://paquier.xyz/postgresql-2/channel-binding-openssl/ */
3373 size_t len = SSL_get_peer_finished(ssl, &c, 0);
3374 int old_pool = store_pool;
3376 SSL_get_peer_finished(ssl, s = store_get((int)len, FALSE), len);
3377 store_pool = POOL_PERM;
3378 tls_in.channelbinding = b64encode_taint(CUS s, (int)len, FALSE);
3379 store_pool = old_pool;
3380 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage %p\n", tls_in.channelbinding);
3383 /* Only used by the server-side tls (tls_in), including tls_getc.
3384 Client-side (tls_out) reads (seem to?) go via
3385 smtp_read_response()/ip_recv().
3386 Hence no need to duplicate for _in and _out.
3388 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
3389 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
3390 ssl_xfer_eof = ssl_xfer_error = FALSE;
3392 receive_getc = tls_getc;
3393 receive_getbuf = tls_getbuf;
3394 receive_get_cache = tls_get_cache;
3395 receive_hasc = tls_hasc;
3396 receive_ungetc = tls_ungetc;
3397 receive_feof = tls_feof;
3398 receive_ferror = tls_ferror;
3400 tls_in.active.sock = fileno(smtp_out);
3401 tls_in.active.tls_ctx = NULL; /* not using explicit ctx for server-side */
3409 tls_client_basic_ctx_init(SSL_CTX * ctx,
3410 host_item * host, smtp_transport_options_block * ob, exim_openssl_state_st * state,
3415 /* Back-compatible old behaviour if tls_verify_certificates is set but both
3416 tls_verify_hosts and tls_try_verify_hosts are not set. Check only the specified
3417 host patterns if one of them is set with content. */
3419 if ( ( ( !ob->tls_verify_hosts || !ob->tls_verify_hosts
3420 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3422 && ( !ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts
3423 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3426 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
3428 client_verify_optional = FALSE;
3429 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
3430 client_verify_optional = TRUE;
3436 if (!expand_check(ob->tls_verify_certificates, US"tls_verify_certificates",
3439 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3441 if (state->lib_state.cabundle)
3442 { DEBUG(D_tls) debug_printf("TLS: CA bundle was preloaded\n"); }
3444 if ((rc = setup_certs(ctx, expcerts, ob->tls_crl, host, errstr)) != OK)
3447 if (expcerts && *expcerts)
3448 setup_cert_verify(ctx, client_verify_optional, verify_callback_client);
3451 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
3453 state->verify_cert_hostnames =
3455 string_domain_utf8_to_alabel(host->certname, NULL);
3459 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
3460 state->verify_cert_hostnames);
3468 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
3471 const char * hostnames[2] = { CS host->name, NULL };
3474 if (DANESSL_init(ssl, NULL, hostnames) != 1)
3475 return tls_error(US"hostnames load", host, NULL, errstr);
3477 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
3478 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
3479 ) if (rr->type == T_TLSA && rr->size > 3)
3481 const uschar * p = rr->data;
3482 uint8_t usage, selector, mtype;
3483 const char * mdname;
3487 /* Only DANE-TA(2) and DANE-EE(3) are supported */
3488 if (usage != 2 && usage != 3) continue;
3495 default: continue; /* Only match-types 0, 1, 2 are supported */
3496 case 0: mdname = NULL; break;
3497 case 1: mdname = "sha256"; break;
3498 case 2: mdname = "sha512"; break;
3502 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
3505 return tls_error(US"tlsa load", host, NULL, errstr);
3506 case 0: /* action not taken */
3510 tls_out.tlsa_usage |= 1<<usage;
3516 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
3519 #endif /*SUPPORT_DANE*/
3523 #ifndef DISABLE_TLS_RESUME
3524 /* On the client, get any stashed session for the given IP from hints db
3525 and apply it to the ssl-connection for attempted resumption. */
3528 tls_retrieve_session(tls_support * tlsp, SSL * ssl, const uschar * key)
3530 tlsp->resumption |= RESUME_SUPPORTED;
3531 if (tlsp->host_resumable)
3533 dbdata_tls_session * dt;
3535 open_db dbblock, * dbm_file;
3537 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
3538 DEBUG(D_tls) debug_printf("checking for resumable session for %s\n", key);
3539 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3541 /* key for the db is the IP */
3542 if ((dt = dbfn_read_with_length(dbm_file, key, &len)))
3544 SSL_SESSION * ss = NULL;
3545 const uschar * sess_asn1 = dt->session;
3547 len -= sizeof(dbdata_tls_session);
3548 if (!(d2i_SSL_SESSION(&ss, &sess_asn1, (long)len)))
3552 ERR_error_string_n(ERR_get_error(),
3553 ssl_errstring, sizeof(ssl_errstring));
3554 debug_printf("decoding session: %s\n", ssl_errstring);
3559 unsigned long lifetime =
3560 #ifdef EXIM_HAVE_SESSION_TICKET
3561 SSL_SESSION_get_ticket_lifetime_hint(ss);
3562 #else /* Use, fairly arbitrilarily, what we as server would */
3563 f.running_in_test_harness ? 6 : ssl_session_timeout;
3565 if (lifetime + dt->time_stamp < time(NULL))
3567 DEBUG(D_tls) debug_printf("session expired\n");
3568 dbfn_delete(dbm_file, key);
3570 else if (!SSL_set_session(ssl, ss))
3574 ERR_error_string_n(ERR_get_error(),
3575 ssl_errstring, sizeof(ssl_errstring));
3576 debug_printf("applying session to ssl: %s\n", ssl_errstring);
3581 DEBUG(D_tls) debug_printf("good session\n");
3582 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
3583 tlsp->verify_override = dt->verify_override;
3584 tlsp->ocsp = dt->ocsp;
3589 DEBUG(D_tls) debug_printf("no session record\n");
3590 dbfn_close(dbm_file);
3596 /* On the client, save the session for later resumption */
3599 tls_save_session_cb(SSL * ssl, SSL_SESSION * ss)
3601 exim_openssl_state_st * cbinfo = SSL_get_ex_data(ssl, tls_exdata_idx);
3604 DEBUG(D_tls) debug_printf("tls_save_session_cb\n");
3606 if (!cbinfo || !(tlsp = cbinfo->tlsp)->host_resumable) return 0;
3608 # ifdef OPENSSL_HAVE_NUM_TICKETS
3609 if (SSL_SESSION_is_resumable(ss)) /* 1.1.1 */
3612 int len = i2d_SSL_SESSION(ss, NULL);
3613 int dlen = sizeof(dbdata_tls_session) + len;
3614 dbdata_tls_session * dt = store_get(dlen, TRUE);
3615 uschar * s = dt->session;
3616 open_db dbblock, * dbm_file;
3618 DEBUG(D_tls) debug_printf("session is resumable\n");
3619 tlsp->resumption |= RESUME_SERVER_TICKET; /* server gave us a ticket */
3621 dt->verify_override = tlsp->verify_override;
3622 dt->ocsp = tlsp->ocsp;
3623 (void) i2d_SSL_SESSION(ss, &s); /* s gets bumped to end */
3625 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3627 const uschar * key = cbinfo->host->address;
3628 dbfn_delete(dbm_file, key);
3629 dbfn_write(dbm_file, key, dt, dlen);
3630 dbfn_close(dbm_file);
3631 DEBUG(D_tls) debug_printf("wrote session (len %u) to db\n",
3640 tls_client_ctx_resume_prehandshake(
3641 exim_openssl_client_tls_ctx * exim_client_ctx, tls_support * tlsp,
3642 smtp_transport_options_block * ob, host_item * host)
3644 /* Should the client request a session resumption ticket? */
3645 if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
3647 tlsp->host_resumable = TRUE;
3649 SSL_CTX_set_session_cache_mode(exim_client_ctx->ctx,
3650 SSL_SESS_CACHE_CLIENT
3651 | SSL_SESS_CACHE_NO_INTERNAL | SSL_SESS_CACHE_NO_AUTO_CLEAR);
3652 SSL_CTX_sess_set_new_cb(exim_client_ctx->ctx, tls_save_session_cb);
3657 tls_client_ssl_resume_prehandshake(SSL * ssl, tls_support * tlsp,
3658 host_item * host, uschar ** errstr)
3660 if (tlsp->host_resumable)
3663 debug_printf("tls_resumption_hosts overrides openssl_options, enabling tickets\n");
3664 SSL_clear_options(ssl, SSL_OP_NO_TICKET);
3666 tls_exdata_idx = SSL_get_ex_new_index(0, 0, 0, 0, 0);
3667 if (!SSL_set_ex_data(ssl, tls_exdata_idx, client_static_state))
3669 tls_error(US"set ex_data", host, NULL, errstr);
3672 debug_printf("tls_exdata_idx %d cbinfo %p\n", tls_exdata_idx, client_static_state);
3675 tlsp->resumption = RESUME_SUPPORTED;
3676 /* Pick up a previous session, saved on an old ticket */
3677 tls_retrieve_session(tlsp, ssl, host->address);
3682 tls_client_resume_posthandshake(exim_openssl_client_tls_ctx * exim_client_ctx,
3685 if (SSL_session_reused(exim_client_ctx->ssl))
3687 DEBUG(D_tls) debug_printf("The session was reused\n");
3688 tlsp->resumption |= RESUME_USED;
3691 #endif /* !DISABLE_TLS_RESUME */
3694 #ifdef EXIM_HAVE_ALPN
3695 /* Expand and convert an Exim list to an ALPN list. False return for fail.
3696 NULL plist return for silent no-ALPN.
3700 tls_alpn_plist(const uschar * tls_alpn, const uschar ** plist, unsigned * plen,
3705 if (!expand_check(tls_alpn, US"tls_alpn", &exp_alpn, errstr))
3710 DEBUG(D_tls) debug_printf("Setting TLS ALPN forced to fail, not sending\n");
3715 /* The server implementation only accepts exactly one protocol name
3716 but it's little extra code complexity in the client. */
3718 const uschar * list = exp_alpn;
3719 uschar * p = store_get(Ustrlen(exp_alpn), is_tainted(exp_alpn)), * s, * t;
3723 for (t = p; s = string_nextinlist(&list, &sep, NULL, 0); t += len)
3725 *t++ = len = (uschar) Ustrlen(s);
3728 *plist = (*plen = t - p) ? p : NULL;
3732 #endif /* EXIM_HAVE_ALPN */
3735 /*************************************************
3736 * Start a TLS session in a client *
3737 *************************************************/
3739 /* Called from the smtp transport after STARTTLS has been accepted.
3742 cctx connection context
3743 conn_args connection details
3744 cookie datum for randomness; can be NULL
3745 tlsp record details of TLS channel configuration here; must be non-NULL
3746 errstr error string pointer
3748 Returns: TRUE for success with TLS session context set in connection context,
3753 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
3754 void * cookie, tls_support * tlsp, uschar ** errstr)
3756 host_item * host = conn_args->host; /* for msgs and option-tests */
3757 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
3758 smtp_transport_options_block * ob = tb
3759 ? (smtp_transport_options_block *)tb->options_block
3760 : &smtp_transport_option_defaults;
3761 exim_openssl_client_tls_ctx * exim_client_ctx;
3762 uschar * expciphers;
3764 static uschar peerdn[256];
3766 #ifndef DISABLE_OCSP
3767 BOOL request_ocsp = FALSE;
3768 BOOL require_ocsp = FALSE;
3772 store_pool = POOL_PERM;
3773 exim_client_ctx = store_get(sizeof(exim_openssl_client_tls_ctx), FALSE);
3774 exim_client_ctx->corked = NULL;
3778 tlsp->tlsa_usage = 0;
3781 #ifndef DISABLE_OCSP
3783 # ifdef SUPPORT_DANE
3784 /*XXX this should be moved to caller, to be common across gnutls/openssl */
3785 if ( conn_args->dane
3786 && ob->hosts_request_ocsp[0] == '*'
3787 && ob->hosts_request_ocsp[1] == '\0'
3790 /* Unchanged from default. Use a safer one under DANE */
3791 request_ocsp = TRUE;
3792 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
3793 " {= {4}{$tls_out_tlsa_usage}} } "
3799 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK))
3800 request_ocsp = TRUE;
3802 # ifdef SUPPORT_DANE
3806 verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3810 rc = tls_init(host, ob,
3811 #ifndef DISABLE_OCSP
3812 (void *)(long)request_ocsp,
3814 cookie, &client_static_state, tlsp, errstr);
3815 if (rc != OK) return FALSE;
3817 exim_client_ctx->ctx = client_static_state->lib_state.lib_ctx;
3819 tlsp->certificate_verified = FALSE;
3820 client_verify_callback_called = FALSE;
3824 if (conn_args->dane)
3826 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
3827 other failures should be treated as problems. */
3828 if (ob->dane_require_tls_ciphers &&
3829 !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
3830 &expciphers, errstr))
3832 if (expciphers && *expciphers == '\0')
3837 !expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
3838 &expciphers, errstr))
3841 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
3842 are separated by underscores. So that I can use either form in my tests, and
3843 also for general convenience, we turn underscores into hyphens here. */
3847 uschar *s = expciphers;
3848 while (*s) { if (*s == '_') *s = '-'; s++; }
3849 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
3850 if (!SSL_CTX_set_cipher_list(exim_client_ctx->ctx, CS expciphers))
3852 tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
3858 if (conn_args->dane)
3860 SSL_CTX_set_verify(exim_client_ctx->ctx,
3861 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
3862 verify_callback_client_dane);
3864 if (!DANESSL_library_init())
3866 tls_error(US"library init", host, NULL, errstr);
3869 if (DANESSL_CTX_init(exim_client_ctx->ctx) <= 0)
3871 tls_error(US"context init", host, NULL, errstr);
3879 if (tls_client_basic_ctx_init(exim_client_ctx->ctx, host, ob,
3880 client_static_state, errstr) != OK)
3883 #ifndef DISABLE_TLS_RESUME
3884 tls_client_ctx_resume_prehandshake(exim_client_ctx, tlsp, ob, host);
3888 if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx)))
3890 tls_error(US"SSL_new", host, NULL, errstr);
3893 SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx));
3895 SSL_set_fd(exim_client_ctx->ssl, cctx->sock);
3896 SSL_set_connect_state(exim_client_ctx->ssl);
3900 if (!expand_check(ob->tls_sni, US"tls_sni", &tlsp->sni, errstr))
3904 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
3906 else if (!Ustrlen(tlsp->sni))
3910 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
3911 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tlsp->sni);
3912 SSL_set_tlsext_host_name(exim_client_ctx->ssl, tlsp->sni);
3914 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
3921 #ifdef EXIM_HAVE_ALPN
3923 const uschar * plist;
3926 if (!tls_alpn_plist(ob->tls_alpn, &plist, &plen, errstr))
3929 if (SSL_set_alpn_protos(exim_client_ctx->ssl, plist, plen) != 0)
3931 tls_error(US"alpn init", host, NULL, errstr);
3935 DEBUG(D_tls) debug_printf("Setting TLS ALPN '%s'\n", ob->tls_alpn);
3938 log_write(0, LOG_MAIN, "ALPN unusable with this OpenSSL library version; ignoring \"%s\"\n",
3943 if (conn_args->dane)
3944 if (dane_tlsa_load(exim_client_ctx->ssl, host, &conn_args->tlsa_dnsa, errstr) != OK)
3948 #ifndef DISABLE_OCSP
3949 /* Request certificate status at connection-time. If the server
3950 does OCSP stapling we will get the callback (set in tls_init()) */
3951 # ifdef SUPPORT_DANE
3955 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
3956 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
3958 { /* Re-eval now $tls_out_tlsa_usage is populated. If
3959 this means we avoid the OCSP request, we wasted the setup
3960 cost in tls_init(). */
3961 require_ocsp = verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
3962 request_ocsp = require_ocsp
3963 || verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3970 SSL_set_tlsext_status_type(exim_client_ctx->ssl, TLSEXT_STATUSTYPE_ocsp);
3971 client_static_state->u_ocsp.client.verify_required = require_ocsp;
3972 tlsp->ocsp = OCSP_NOT_RESP;
3976 #ifndef DISABLE_TLS_RESUME
3977 if (!tls_client_ssl_resume_prehandshake(exim_client_ctx->ssl, tlsp, host,
3982 #ifndef DISABLE_EVENT
3983 client_static_state->event_action = tb ? tb->event_action : NULL;
3986 /* There doesn't seem to be a built-in timeout on connection. */
3988 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
3989 sigalrm_seen = FALSE;
3990 ALARM(ob->command_timeout);
3991 rc = SSL_connect(exim_client_ctx->ssl);
3995 if (conn_args->dane)
3996 DANESSL_cleanup(exim_client_ctx->ssl);
4001 tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, errstr);
4007 debug_printf("SSL_connect succeeded\n");
4008 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
4010 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
4011 SSL_SESSION_print_keylog(bp, SSL_get_session(exim_client_ctx->ssl));
4017 #ifndef DISABLE_TLS_RESUME
4018 tls_client_resume_posthandshake(exim_client_ctx, tlsp);
4021 #ifdef EXIM_HAVE_ALPN
4022 if (ob->tls_alpn) /* We requested. See what was negotiated. */
4024 const uschar * name;
4027 SSL_get0_alpn_selected(exim_client_ctx->ssl, &name, &len);
4029 { DEBUG(D_tls) debug_printf("ALPN negotiated %u: '%.*s'\n", len, (int)*name, name+1); }
4030 else if (verify_check_given_host(CUSS &ob->hosts_require_alpn, host) == OK)
4032 /* Would like to send a relevant fatal Alert, but OpenSSL has no API */
4033 tls_error(US"handshake", host, US"ALPN required but not negotiated", errstr);
4039 #ifdef SSL_get_extms_support
4040 tlsp->ext_master_secret = SSL_get_extms_support(exim_client_ctx->ssl) == 1;
4042 peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn));
4044 tlsp->ver = tlsver_name(exim_client_ctx->ssl);
4045 tlsp->cipher = construct_cipher_name(exim_client_ctx->ssl, tlsp->ver, &tlsp->bits);
4046 tlsp->cipher_stdname = cipher_stdname_ssl(exim_client_ctx->ssl);
4048 /* Record the certificate we presented */
4050 X509 * crt = SSL_get_certificate(exim_client_ctx->ssl);
4051 tlsp->ourcert = crt ? X509_dup(crt) : NULL;
4054 /*XXX will this work with continued-TLS? */
4055 /* Channel-binding info for authenticators */
4058 size_t len = SSL_get_finished(exim_client_ctx->ssl, &c, 0);
4059 int old_pool = store_pool;
4061 SSL_get_finished(exim_client_ctx->ssl, s = store_get((int)len, TRUE), len);
4062 store_pool = POOL_PERM;
4063 tlsp->channelbinding = b64encode_taint(CUS s, (int)len, TRUE);
4064 store_pool = old_pool;
4065 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage %p %p\n", tlsp->channelbinding, tlsp);
4068 tlsp->active.sock = cctx->sock;
4069 tlsp->active.tls_ctx = exim_client_ctx;
4070 cctx->tls_ctx = exim_client_ctx;
4079 tls_refill(unsigned lim)
4081 SSL * ssl = state_server.lib_state.lib_ssl;
4085 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
4086 ssl_xfer_buffer, ssl_xfer_buffer_size);
4089 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
4090 inbytes = SSL_read(ssl, CS ssl_xfer_buffer,
4091 MIN(ssl_xfer_buffer_size, lim));
4092 error = SSL_get_error(ssl, inbytes);
4093 if (smtp_receive_timeout > 0) ALARM_CLR(0);
4095 if (had_command_timeout) /* set by signal handler */
4096 smtp_command_timeout_exit(); /* does not return */
4097 if (had_command_sigterm)
4098 smtp_command_sigterm_exit();
4099 if (had_data_timeout)
4100 smtp_data_timeout_exit();
4101 if (had_data_sigint)
4102 smtp_data_sigint_exit();
4104 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
4105 closed down, not that the socket itself has been closed down. Revert to
4106 non-SSL handling. */
4110 case SSL_ERROR_NONE:
4113 case SSL_ERROR_ZERO_RETURN:
4114 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
4116 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
4119 tls_close(NULL, TLS_NO_SHUTDOWN);
4122 /* Handle genuine errors */
4124 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4125 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
4126 ssl_xfer_error = TRUE;
4130 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
4131 DEBUG(D_tls) if (error == SSL_ERROR_SYSCALL)
4132 debug_printf(" - syscall %s\n", strerror(errno));
4133 ssl_xfer_error = TRUE;
4137 #ifndef DISABLE_DKIM
4138 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
4140 ssl_xfer_buffer_hwm = inbytes;
4141 ssl_xfer_buffer_lwm = 0;
4146 /*************************************************
4147 * TLS version of getc *
4148 *************************************************/
4150 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
4151 it refills the buffer via the SSL reading function.
4153 Arguments: lim Maximum amount to read/buffer
4154 Returns: the next character or EOF
4156 Only used by the server-side TLS.
4160 tls_getc(unsigned lim)
4162 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
4163 if (!tls_refill(lim))
4164 return ssl_xfer_error ? EOF : smtp_getc(lim);
4166 /* Something in the buffer; return next uschar */
4168 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
4174 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm;
4178 tls_getbuf(unsigned * len)
4183 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
4184 if (!tls_refill(*len))
4186 if (!ssl_xfer_error) return smtp_getbuf(len);
4191 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
4193 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
4194 ssl_xfer_buffer_lwm += size;
4201 tls_get_cache(unsigned lim)
4203 #ifndef DISABLE_DKIM
4204 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
4205 debug_printf("tls_get_cache\n");
4209 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
4215 tls_could_getc(void)
4217 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm
4218 || SSL_pending(state_server.lib_state.lib_ssl) > 0;
4222 /*************************************************
4223 * Read bytes from TLS channel *
4224 *************************************************/
4228 ct_ctx client context pointer, or NULL for the one global server context
4232 Returns: the number of bytes read
4233 -1 after a failed read, including EOF
4235 Only used by the client-side TLS.
4239 tls_read(void * ct_ctx, uschar *buff, size_t len)
4241 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
4242 : state_server.lib_state.lib_ssl;
4246 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
4247 buff, (unsigned int)len);
4250 inbytes = SSL_read(ssl, CS buff, len);
4251 error = SSL_get_error(ssl, inbytes);
4253 if (error == SSL_ERROR_ZERO_RETURN)
4255 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
4258 else if (error != SSL_ERROR_NONE)
4268 /*************************************************
4269 * Write bytes down TLS channel *
4270 *************************************************/
4274 ct_ctx client context pointer, or NULL for the one global server context
4277 more further data expected soon
4279 Returns: the number of bytes after a successful write,
4280 -1 after a failed write
4282 Used by both server-side and client-side TLS. Calling with len zero and more unset
4283 will flush buffered writes; buff can be null for this case.
4287 tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
4290 int outbytes, error;
4292 ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
4293 : state_server.lib_state.lib_ssl;
4294 static gstring * server_corked = NULL;
4295 gstring ** corkedp = ct_ctx
4296 ? &((exim_openssl_client_tls_ctx *)ct_ctx)->corked : &server_corked;
4297 gstring * corked = *corkedp;
4299 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
4300 buff, (unsigned long)len, more ? ", more" : "");
4302 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
4303 "more" is notified. This hack is only ok if small amounts are involved AND only
4304 one stream does it, in one context (i.e. no store reset). Currently it is used
4305 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only.
4306 We support callouts done by the server process by using a separate client
4307 context for the stashed information. */
4308 /* + if PIPE_COMMAND, banner & ehlo-resp for smmtp-on-connect. Suspect there's
4309 a store reset there, so use POOL_PERM. */
4310 /* + if CHUNKING, cmds EHLO,MAIL,RCPT(s),BDAT */
4314 if (!len) buff = US &error; /* dummy just so that string_catn is ok */
4316 int save_pool = store_pool;
4317 store_pool = POOL_PERM;
4319 corked = string_catn(corked, buff, len);
4321 store_pool = save_pool;
4328 buff = CUS corked->s;
4333 for (int left = len; left > 0;)
4335 DEBUG(D_tls) debug_printf("SSL_write(%p, %p, %d)\n", ssl, buff, left);
4337 outbytes = SSL_write(ssl, CS buff, left);
4338 error = SSL_get_error(ssl, outbytes);
4339 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
4342 case SSL_ERROR_NONE: /* the usual case */
4348 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4349 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
4352 case SSL_ERROR_ZERO_RETURN:
4353 log_write(0, LOG_MAIN, "SSL channel closed on write");
4356 case SSL_ERROR_SYSCALL:
4357 if (ct_ctx || errno != ECONNRESET || !f.smtp_in_quit)
4358 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
4359 sender_fullhost ? sender_fullhost : US"<unknown>",
4361 else if (LOGGING(protocol_detail))
4362 log_write(0, LOG_MAIN, "[%s] after QUIT, client reset TCP before"
4363 " SMTP response and TLS close\n", sender_host_address);
4365 DEBUG(D_tls) debug_printf("[%s] SSL_write: after QUIT,"
4366 " client reset TCP before TLS close\n", sender_host_address);
4370 log_write(0, LOG_MAIN, "SSL_write error %d", error);
4381 ct_ctx client TLS context pointer, or NULL for the one global server context
4385 tls_shutdown_wr(void * ct_ctx)
4387 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4388 SSL ** sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4389 int * fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4392 if (*fdp < 0) return; /* TLS was not active */
4394 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
4396 HDEBUG(D_transport|D_tls|D_acl|D_v) debug_printf_indent(" SMTP(TLS shutdown)>>\n");
4397 rc = SSL_shutdown(*sslp);
4398 if (rc < 0) DEBUG(D_tls)
4400 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4401 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4405 /*************************************************
4406 * Close down a TLS session *
4407 *************************************************/
4409 /* This is also called from within a delivery subprocess forked from the
4410 daemon, to shut down the TLS library, without actually doing a shutdown (which
4411 would tamper with the SSL session in the parent process).
4414 ct_ctx client TLS context pointer, or NULL for the one global server context
4415 do_shutdown 0 no data-flush or TLS close-alert
4416 1 if TLS close-alert is to be sent,
4417 2 if also response to be waited for
4421 Used by both server-side and client-side TLS.
4425 tls_close(void * ct_ctx, int do_shutdown)
4427 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4428 SSL ** sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4429 int * fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4431 if (*fdp < 0) return; /* TLS was not active */
4436 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
4437 do_shutdown > 1 ? " (with response-wait)" : "");
4439 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
4441 if ( (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
4445 rc = SSL_shutdown(*sslp); /* wait for response */
4449 if (rc < 0) DEBUG(D_tls)
4451 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4452 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4456 if (!o_ctx) /* server side */
4458 #ifndef DISABLE_OCSP
4459 sk_X509_pop_free(state_server.verify_stack, X509_free);
4460 state_server.verify_stack = NULL;
4463 receive_getc = smtp_getc;
4464 receive_getbuf = smtp_getbuf;
4465 receive_get_cache = smtp_get_cache;
4466 receive_hasc = smtp_hasc;
4467 receive_ungetc = smtp_ungetc;
4468 receive_feof = smtp_feof;
4469 receive_ferror = smtp_ferror;
4470 tls_in.active.tls_ctx = NULL;
4472 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
4483 /*************************************************
4484 * Let tls_require_ciphers be checked at startup *
4485 *************************************************/
4487 /* The tls_require_ciphers option, if set, must be something which the
4490 Returns: NULL on success, or error message
4494 tls_validate_require_cipher(void)
4497 uschar *s, *expciphers, *err;
4501 if (!(tls_require_ciphers && *tls_require_ciphers))
4504 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
4506 return US"failed to expand tls_require_ciphers";
4508 if (!(expciphers && *expciphers))
4511 /* normalisation ripped from above */
4513 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
4517 if (lib_ctx_new(&ctx, NULL, &err) == OK)
4520 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
4522 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
4524 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4525 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
4526 expciphers, ssl_errstring);
4537 /*************************************************
4538 * Report the library versions. *
4539 *************************************************/
4541 /* There have historically been some issues with binary compatibility in
4542 OpenSSL libraries; if Exim (like many other applications) is built against
4543 one version of OpenSSL but the run-time linker picks up another version,
4544 it can result in serious failures, including crashing with a SIGSEGV. So
4545 report the version found by the compiler and the run-time version.
4547 Note: some OS vendors backport security fixes without changing the version
4548 number/string, and the version date remains unchanged. The _build_ date
4549 will change, so we can more usefully assist with version diagnosis by also
4550 reporting the build date.
4552 Arguments: a FILE* to print the results to
4557 tls_version_report(FILE *f)
4559 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
4562 OPENSSL_VERSION_TEXT,
4563 SSLeay_version(SSLEAY_VERSION),
4564 SSLeay_version(SSLEAY_BUILT_ON));
4565 /* third line is 38 characters for the %s and the line is 73 chars long;
4566 the OpenSSL output includes a "built on: " prefix already. */
4572 /*************************************************
4573 * Random number generation *
4574 *************************************************/
4576 /* Pseudo-random number generation. The result is not expected to be
4577 cryptographically strong but not so weak that someone will shoot themselves
4578 in the foot using it as a nonce in input in some email header scheme or
4579 whatever weirdness they'll twist this into. The result should handle fork()
4580 and avoid repeating sequences. OpenSSL handles that for us.
4584 Returns a random number in range [0, max-1]
4588 vaguely_random_number(int max)
4592 static pid_t pidlast = 0;
4594 uschar smallbuf[sizeof(r)];
4600 if (pidnow != pidlast)
4602 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
4603 is unique for each thread", this doesn't apparently apply across processes,
4604 so our own warning from vaguely_random_number_fallback() applies here too.
4605 Fix per PostgreSQL. */
4611 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
4615 gettimeofday(&r.tv, NULL);
4618 RAND_seed(US (&r), sizeof(r));
4620 /* We're after pseudo-random, not random; if we still don't have enough data
4621 in the internal PRNG then our options are limited. We could sleep and hope
4622 for entropy to come along (prayer technique) but if the system is so depleted
4623 in the first place then something is likely to just keep taking it. Instead,
4624 we'll just take whatever little bit of pseudo-random we can still manage to
4627 needed_len = sizeof(r);
4628 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
4629 asked for a number less than 10. */
4630 for (r = max, i = 0; r; ++i)
4636 #ifdef EXIM_HAVE_RAND_PSEUDO
4637 /* We do not care if crypto-strong */
4638 i = RAND_pseudo_bytes(smallbuf, needed_len);
4640 i = RAND_bytes(smallbuf, needed_len);
4646 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
4647 return vaguely_random_number_fallback(max);
4651 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
4654 /* We don't particularly care about weighted results; if someone wants
4655 smooth distribution and cares enough then they should submit a patch then. */
4662 /*************************************************
4663 * OpenSSL option parse *
4664 *************************************************/
4666 /* Parse one option for tls_openssl_options_parse below
4669 name one option name
4670 value place to store a value for it
4671 Returns success or failure in parsing
4677 tls_openssl_one_option_parse(uschar *name, long *value)
4680 int last = exim_openssl_options_size;
4681 while (last > first)
4683 int middle = (first + last)/2;
4684 int c = Ustrcmp(name, exim_openssl_options[middle].name);
4687 *value = exim_openssl_options[middle].value;
4701 /*************************************************
4702 * OpenSSL option parsing logic *
4703 *************************************************/
4705 /* OpenSSL has a number of compatibility options which an administrator might
4706 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
4707 we look like log_selector.
4710 option_spec the administrator-supplied string of options
4711 results ptr to long storage for the options bitmap
4712 Returns success or failure
4716 tls_openssl_options_parse(uschar *option_spec, long *results)
4719 uschar * exp, * end;
4720 BOOL adding, item_parsed;
4722 /* Server: send no (<= TLS1.2) session tickets */
4723 result = SSL_OP_NO_TICKET;
4725 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
4726 from default because it increases BEAST susceptibility. */
4727 #ifdef SSL_OP_NO_SSLv2
4728 result |= SSL_OP_NO_SSLv2;
4730 #ifdef SSL_OP_NO_SSLv3
4731 result |= SSL_OP_NO_SSLv3;
4733 #ifdef SSL_OP_SINGLE_DH_USE
4734 result |= SSL_OP_SINGLE_DH_USE;
4736 #ifdef SSL_OP_NO_RENEGOTIATION
4737 result |= SSL_OP_NO_RENEGOTIATION;
4746 if (!expand_check(option_spec, US"openssl_options", &exp, &end))
4749 for (uschar * s = exp; *s; /**/)
4751 while (isspace(*s)) ++s;
4754 if (*s != '+' && *s != '-')
4756 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
4757 "+ or - expected but found \"%s\"\n", s);
4760 adding = *s++ == '+';
4761 for (end = s; *end && !isspace(*end); ) end++;
4762 item_parsed = tls_openssl_one_option_parse(string_copyn(s, end-s), &item);
4765 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
4768 DEBUG(D_tls) debug_printf("openssl option, %s %08lx: %08lx (%s)\n",
4769 adding ? "adding to " : "removing from", result, item, s);
4781 #endif /*!MACRO_PREDEF*/
4784 /* End of tls-openssl.c */