1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) The Exim Maintainers 2020 - 2022 */
6 /* Copyright (c) University of Cambridge 1995 - 2019 */
7 /* See the file NOTICE for conditions of use and distribution. */
8 /* SPDX-License-Identifier: GPL-2.0-or-later */
10 /* Portions Copyright (c) The OpenSSL Project 1999 */
12 /* This module provides the TLS (aka SSL) support for Exim using the OpenSSL
13 library. It is #included into the tls.c file when that library is used. The
14 code herein is based on a patch that was originally contributed by Steve
15 Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara.
17 No cryptographic code is included in Exim. All this module does is to call
18 functions from the OpenSSL library. */
23 #include <openssl/lhash.h>
24 #include <openssl/ssl.h>
25 #include <openssl/err.h>
26 #include <openssl/rand.h>
27 #ifndef OPENSSL_NO_ECDH
28 # include <openssl/ec.h>
31 # include <openssl/ocsp.h>
39 # define EXIM_OCSP_SKEW_SECONDS (300L)
40 # define EXIM_OCSP_MAX_AGE (-1L)
43 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
44 # define EXIM_HAVE_OPENSSL_TLSEXT
46 #if OPENSSL_VERSION_NUMBER >= 0x00908000L
47 # define EXIM_HAVE_RSA_GENKEY_EX
49 #if OPENSSL_VERSION_NUMBER >= 0x10100000L
50 # define EXIM_HAVE_OCSP_RESP_COUNT
51 # define OPENSSL_AUTO_SHA256
52 # define OPENSSL_MIN_PROTO_VERSION
54 # define EXIM_HAVE_EPHEM_RSA_KEX
55 # define EXIM_HAVE_RAND_PSEUDO
57 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
58 # define EXIM_HAVE_SHA256
61 /* X509_check_host provides sane certificate hostname checking, but was added
62 to OpenSSL late, after other projects forked off the code-base. So in
63 addition to guarding against the base version number, beware that LibreSSL
64 does not (at this time) support this function.
66 If LibreSSL gains a different API, perhaps via libtls, then we'll probably
67 opt to disentangle and ask a LibreSSL user to provide glue for a third
68 crypto provider for libtls instead of continuing to tie the OpenSSL glue
69 into even twistier knots. If LibreSSL gains the same API, we can just
70 change this guard and punt the issue for a while longer. */
72 #ifndef LIBRESSL_VERSION_NUMBER
73 # if OPENSSL_VERSION_NUMBER >= 0x010100000L
74 # define EXIM_HAVE_OPENSSL_CHECKHOST
75 # define EXIM_HAVE_OPENSSL_DH_BITS
76 # define EXIM_HAVE_OPENSSL_TLS_METHOD
77 # define EXIM_HAVE_OPENSSL_KEYLOG
78 # define EXIM_HAVE_OPENSSL_CIPHER_GET_ID
79 # define EXIM_HAVE_SESSION_TICKET
80 # define EXIM_HAVE_OPESSL_TRACE
81 # define EXIM_HAVE_OPESSL_GET0_SERIAL
82 # define EXIM_HAVE_OPESSL_OCSP_RESP_GET0_CERTS
83 # define EXIM_HAVE_SSL_GET0_VERIFIED_CHAIN
85 # define EXIM_HAVE_OCSP
87 # define EXIM_HAVE_ALPN /* fail ret from hshake-cb is ignored by LibreSSL */
89 # define EXIM_NEED_OPENSSL_INIT
91 # if OPENSSL_VERSION_NUMBER >= 0x010000000L \
92 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
93 # define EXIM_HAVE_OPENSSL_CHECKHOST
97 #if LIBRESSL_VERSION_NUMBER >= 0x3040000fL
98 # define EXIM_HAVE_OPENSSL_CIPHER_GET_ID
101 #if !defined(LIBRESSL_VERSION_NUMBER) && (OPENSSL_VERSION_NUMBER >= 0x030000000L)
102 # define EXIM_HAVE_EXPORT_CHNL_BNGNG
103 # define EXIM_HAVE_OPENSSL_X509_STORE_GET1_ALL_CERTS
106 #if !defined(LIBRESSL_VERSION_NUMBER) \
107 || LIBRESSL_VERSION_NUMBER >= 0x20010000L
108 # if !defined(OPENSSL_NO_ECDH)
109 # if OPENSSL_VERSION_NUMBER >= 0x0090800fL
110 # define EXIM_HAVE_ECDH
112 # if OPENSSL_VERSION_NUMBER >= 0x10002000L
113 # define EXIM_HAVE_OPENSSL_EC_NIST2NID
118 #ifndef LIBRESSL_VERSION_NUMBER
119 # if OPENSSL_VERSION_NUMBER >= 0x010101000L
120 # define OPENSSL_HAVE_KEYLOG_CB
121 # define OPENSSL_HAVE_NUM_TICKETS
122 # define EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
123 # define EXIM_HAVE_EXP_CHNL_BNGNG
124 # define EXIM_HAVE_OPENSSL_OCSP_RESP_GET0_SIGNER
126 # define OPENSSL_BAD_SRVR_OURCERT
130 #if !defined(LIBRESSL_VERSION_NUMBER) && (OPENSSL_VERSION_NUMBER >= 0x010002000L)
131 # define EXIM_HAVE_EXPORT_CHNL_BNGNG
134 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
135 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
136 # define DISABLE_OCSP
139 #ifndef DISABLE_TLS_RESUME
140 # if OPENSSL_VERSION_NUMBER < 0x0101010L
141 # error OpenSSL version too old for session-resumption
145 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
146 # include <openssl/x509v3.h>
149 #ifndef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
150 # ifndef EXIM_HAVE_OPENSSL_CIPHER_GET_ID
151 # define SSL_CIPHER_get_id(c) (c->id)
153 # ifndef MACRO_PREDEF
154 # include "tls-cipher-stdname.c"
158 /*************************************************
159 * OpenSSL option parse *
160 *************************************************/
162 typedef struct exim_openssl_option {
165 } exim_openssl_option;
166 /* We could use a macro to expand, but we need the ifdef and not all the
167 options document which version they were introduced in. Policylet: include
168 all options unless explicitly for DTLS, let the administrator choose which
171 This list is current as of:
174 XXX could we autobuild this list, as with predefined-macros?
175 Seems just parsing ssl.h for SSL_OP_.* would be enough (except to exclude DTLS).
176 Also allow a numeric literal?
178 static exim_openssl_option exim_openssl_options[] = {
179 /* KEEP SORTED ALPHABETICALLY! */
181 { US"all", (long) SSL_OP_ALL },
183 #ifdef SSL_OP_ALLOW_NO_DHE_KEX
184 { US"allow_no_dhe_kex", SSL_OP_ALLOW_NO_DHE_KEX },
186 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
187 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
189 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
190 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
192 #ifdef SSL_OP_CRYPTOPRO_TLSEXT_BUG
193 { US"cryptopro_tlsext_bug", SSL_OP_CRYPTOPRO_TLSEXT_BUG },
195 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
196 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
198 #ifdef SSL_OP_ENABLE_MIDDLEBOX_COMPAT
199 { US"enable_middlebox_compat", SSL_OP_ENABLE_MIDDLEBOX_COMPAT },
201 #ifdef SSL_OP_EPHEMERAL_RSA
202 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
204 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
205 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
207 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
208 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
210 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
211 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
213 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
214 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
216 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
217 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
219 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
220 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
222 #ifdef SSL_OP_NO_ANTI_REPLAY
223 { US"no_anti_replay", SSL_OP_NO_ANTI_REPLAY },
225 #ifdef SSL_OP_NO_COMPRESSION
226 { US"no_compression", SSL_OP_NO_COMPRESSION },
228 #ifdef SSL_OP_NO_ENCRYPT_THEN_MAC
229 { US"no_encrypt_then_mac", SSL_OP_NO_ENCRYPT_THEN_MAC },
231 #ifdef SSL_OP_NO_RENEGOTIATION
232 { US"no_renegotiation", SSL_OP_NO_RENEGOTIATION },
234 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
235 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
237 #ifdef SSL_OP_NO_SSLv2
238 { US"no_sslv2", SSL_OP_NO_SSLv2 },
240 #ifdef SSL_OP_NO_SSLv3
241 { US"no_sslv3", SSL_OP_NO_SSLv3 },
243 #ifdef SSL_OP_NO_TICKET
244 { US"no_ticket", SSL_OP_NO_TICKET },
246 #ifdef SSL_OP_NO_TLSv1
247 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
249 #ifdef SSL_OP_NO_TLSv1_1
250 # if OPENSSL_VERSION_NUMBER < 0x30000000L
251 # if SSL_OP_NO_TLSv1_1 == 0x00000400L
252 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
253 # warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
254 # define NO_SSL_OP_NO_TLSv1_1
257 # ifndef NO_SSL_OP_NO_TLSv1_1
258 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
261 #ifdef SSL_OP_NO_TLSv1_2
262 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
264 #ifdef SSL_OP_NO_TLSv1_3
265 { US"no_tlsv1_3", SSL_OP_NO_TLSv1_3 },
267 #ifdef SSL_OP_PRIORITIZE_CHACHA
268 { US"prioritize_chacha", SSL_OP_PRIORITIZE_CHACHA },
270 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
271 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
273 #ifdef SSL_OP_SINGLE_DH_USE
274 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
276 #ifdef SSL_OP_SINGLE_ECDH_USE
277 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
279 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
280 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
282 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
283 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
285 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
286 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
288 #ifdef SSL_OP_TLS_D5_BUG
289 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
291 #ifdef SSL_OP_TLS_ROLLBACK_BUG
292 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
294 #ifdef SSL_OP_TLSEXT_PADDING
295 { US"tlsext_padding", SSL_OP_TLSEXT_PADDING },
300 static int exim_openssl_options_size = nelem(exim_openssl_options);
301 static long init_options = 0;
310 for (struct exim_openssl_option * o = exim_openssl_options;
311 o < exim_openssl_options + nelem(exim_openssl_options); o++)
313 /* Trailing X is workaround for problem with _OPT_OPENSSL_NO_TLSV1
314 being a ".ifdef _OPT_OPENSSL_NO_TLSV1_3" match */
316 spf(buf, sizeof(buf), US"_OPT_OPENSSL_%T_X", o->name);
317 builtin_macro_create(buf);
320 # ifndef DISABLE_TLS_RESUME
321 builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING );
323 # ifdef SSL_OP_NO_TLSv1_3
324 builtin_macro_create(US"_HAVE_TLS1_3");
326 # ifdef OPENSSL_BAD_SRVR_OURCERT
327 builtin_macro_create(US"_TLS_BAD_MULTICERT_IN_OURCERT");
329 # ifdef EXIM_HAVE_OCSP
330 builtin_macro_create(US"_HAVE_TLS_OCSP");
331 builtin_macro_create(US"_HAVE_TLS_OCSP_LIST");
333 # ifdef EXIM_HAVE_ALPN
334 builtin_macro_create(US"_HAVE_TLS_ALPN");
339 /******************************************************************************/
341 /* Structure for collecting random data for seeding. */
343 typedef struct randstuff {
348 /* Local static variables */
350 static BOOL client_verify_callback_called = FALSE;
351 static BOOL server_verify_callback_called = FALSE;
352 static const uschar *sid_ctx = US"exim";
354 /* We have three different contexts to care about.
356 Simple case: client, `client_ctx`
357 As a client, we can be doing a callout or cut-through delivery while receiving
358 a message. So we have a client context, which should have options initialised
359 from the SMTP Transport. We may also concurrently want to make TLS connections
360 to utility daemons, so client-contexts are allocated and passed around in call
361 args rather than using a gobal.
364 There are two cases: with and without ServerNameIndication from the client.
365 Given TLS SNI, we can be using different keys, certs and various other
366 configuration settings, because they're re-expanded with $tls_sni set. This
367 allows vhosting with TLS. This SNI is sent in the handshake.
368 A client might not send SNI, so we need a fallback, and an initial setup too.
369 So as a server, we start out using `server_ctx`.
370 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
371 `server_sni` from `server_ctx` and then initialise settings by re-expanding
379 } exim_openssl_client_tls_ctx;
382 /* static SSL_CTX *server_ctx = NULL; */
383 /* static SSL *server_ssl = NULL; */
385 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
386 static SSL_CTX *server_sni = NULL;
388 #ifdef EXIM_HAVE_ALPN
389 static BOOL server_seen_alpn = FALSE;
392 static char ssl_errstring[256];
394 static int ssl_session_timeout = 7200; /* Two hours */
395 static BOOL client_verify_optional = FALSE;
396 static BOOL server_verify_optional = FALSE;
398 static BOOL reexpand_tls_files_for_sni = FALSE;
401 typedef struct ocsp_resp {
402 struct ocsp_resp * next;
403 OCSP_RESPONSE * resp;
406 typedef struct exim_openssl_state {
407 exim_tlslib_state lib_state;
408 #define lib_ctx libdata0
409 #define lib_ssl libdata1
412 uschar * certificate;
419 const uschar *file_expanded;
420 ocsp_resplist *olist;
421 STACK_OF(X509) *verify_stack; /* chain for verifying the proof */
424 X509_STORE *verify_store; /* non-null if status requested */
425 uschar *verify_errstr; /* only if _required */
426 BOOL verify_required;
431 /* these are cached from first expand */
432 uschar * server_cipher_list;
433 /* only passed down to tls_error: */
435 const uschar * verify_cert_hostnames;
436 #ifndef DISABLE_EVENT
437 uschar * event_action;
439 } exim_openssl_state_st;
441 /* should figure out a cleanup of API to handle state preserved per
442 implementation, for various reasons, which can be void * in the APIs.
443 For now, we hack around it. */
444 exim_openssl_state_st *client_static_state = NULL; /*XXX should not use static; multiple concurrent clients! */
445 exim_openssl_state_st state_server = {.is_server = TRUE};
448 setup_certs(SSL_CTX * sctx, uschar ** certs, uschar * crl, host_item * host,
453 static int tls_server_stapling_cb(SSL *s, void *arg);
454 static void x509_stack_dump_cert_s_names(const STACK_OF(X509) * sk);
455 static void x509_store_dump_cert_s_names(X509_STORE * store);
460 /* Daemon-called, before every connection, key create/rotate */
461 #ifndef DISABLE_TLS_RESUME
462 static void tk_init(void);
463 static int tls_exdata_idx = -1;
467 tls_per_lib_daemon_tick(void)
469 #ifndef DISABLE_TLS_RESUME
474 /* Called once at daemon startup */
477 tls_per_lib_daemon_init(void)
479 tls_daemon_creds_reload();
483 /*************************************************
485 *************************************************/
487 /* Called from lots of places when errors occur before actually starting to do
488 the TLS handshake, that is, while the session is still in clear. Always returns
489 DEFER for a server and FAIL for a client so that most calls can use "return
490 tls_error(...)" to do this processing and then give an appropriate return. A
491 single function is used for both server and client, because it is called from
492 some shared functions.
495 prefix text to include in the logged error
496 host NULL if setting up a server;
497 the connected host if setting up a client
498 msg error message or NULL if we should ask OpenSSL
499 errstr pointer to output error message
501 Returns: OK/DEFER/FAIL
505 tls_error(uschar * prefix, const host_item * host, uschar * msg, uschar ** errstr)
509 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
510 msg = US ssl_errstring;
513 msg = string_sprintf("(%s): %s", prefix, msg);
514 DEBUG(D_tls) debug_printf("TLS error '%s'\n", msg);
515 if (errstr) *errstr = msg;
516 return host ? FAIL : DEFER;
521 /**************************************************
522 * General library initalisation *
523 **************************************************/
526 lib_rand_init(void * addr)
529 if (!RAND_status()) return TRUE;
531 gettimeofday(&r.tv, NULL);
533 RAND_seed(US (&r), sizeof(r));
534 RAND_seed(US big_buffer, big_buffer_size);
535 if (addr) RAND_seed(US addr, sizeof(addr));
537 return RAND_status();
542 tls_openssl_init(void)
544 static BOOL once = FALSE;
548 #ifdef EXIM_NEED_OPENSSL_INIT
549 SSL_load_error_strings(); /* basic set up */
550 OpenSSL_add_ssl_algorithms();
553 #if defined(EXIM_HAVE_SHA256) && !defined(OPENSSL_AUTO_SHA256)
554 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
555 list of available digests. */
556 EVP_add_digest(EVP_sha256());
559 (void) lib_rand_init(NULL);
560 (void) tls_openssl_options_parse(openssl_options, &init_options);
565 /*************************************************
566 * Initialize for DH *
567 *************************************************/
569 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
573 sctx The current SSL CTX (inbound or outbound)
574 dhparam DH parameter file or fixed parameter identity string
575 errstr error string pointer
577 Returns: TRUE if OK (nothing to set up, or setup worked)
581 init_dh(SSL_CTX * sctx, uschar * dhparam, uschar ** errstr)
584 #if OPENSSL_VERSION_NUMBER < 0x30000000L
593 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded, errstr))
596 if (!dhexpanded || !*dhexpanded)
597 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
598 else if (dhexpanded[0] == '/')
600 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
602 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
603 NULL, US strerror(errno), errstr);
609 if (Ustrcmp(dhexpanded, "none") == 0)
611 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
615 if (!(pem = std_dh_prime_named(dhexpanded)))
617 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
618 NULL, US strerror(errno), errstr);
621 bio = BIO_new_mem_buf(CS pem, -1);
625 #if OPENSSL_VERSION_NUMBER < 0x30000000L
626 dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)
628 pkey = PEM_read_bio_Parameters_ex(bio, NULL, NULL, NULL)
633 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
638 /* note: our default limit of 2236 is not a multiple of 8; the limit comes from
639 an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with 2236.
640 But older OpenSSL can only report in bytes (octets), not bits. If someone wants
641 to dance at the edge, then they can raise the limit or use current libraries. */
643 #if OPENSSL_VERSION_NUMBER < 0x30000000L
644 # ifdef EXIM_HAVE_OPENSSL_DH_BITS
645 /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022
646 This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */
647 dh_bitsize = DH_bits(dh);
649 dh_bitsize = 8 * DH_size(dh);
652 dh_bitsize = EVP_PKEY_get_bits(pkey);
655 /* Even if it is larger, we silently return success rather than cause things to
656 fail out, so that a too-large DH will not knock out all TLS; it's a debatable
657 choice. Likewise for a failing attempt to set one. */
659 if (dh_bitsize <= tls_dh_max_bits)
662 #if OPENSSL_VERSION_NUMBER < 0x30000000L
663 SSL_CTX_set_tmp_dh(sctx, dh)
665 SSL_CTX_set0_tmp_dh_pkey(sctx, pkey)
669 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
670 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (D-H param setting '%s'): %s",
671 dhexpanded ? dhexpanded : US"default", ssl_errstring);
672 #if OPENSSL_VERSION_NUMBER >= 0x30000000L
673 /* EVP_PKEY_free(pkey); crashes */
678 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
679 dhexpanded ? dhexpanded : US"default", dh_bitsize);
683 debug_printf("dhparams '%s' %d bits, is > tls_dh_max_bits limit of %d\n",
684 dhexpanded ? dhexpanded : US"default", dh_bitsize, tls_dh_max_bits);
686 #if OPENSSL_VERSION_NUMBER < 0x30000000L
689 /* The EVP_PKEY ownership stays with the ctx; do not free it */
698 /*************************************************
699 * Initialize for ECDH *
700 *************************************************/
702 /* Load parameters for ECDH encryption. Server only.
704 For now, we stick to NIST P-256 because: it's simple and easy to configure;
705 it avoids any patent issues that might bite redistributors; despite events in
706 the news and concerns over curve choices, we're not cryptographers, we're not
707 pretending to be, and this is "good enough" to be better than no support,
708 protecting against most adversaries. Given another year or two, there might
709 be sufficient clarity about a "right" way forward to let us make an informed
710 decision, instead of a knee-jerk reaction.
712 Longer-term, we should look at supporting both various named curves and
713 external files generated with "openssl ecparam", much as we do for init_dh().
714 We should also support "none" as a value, to explicitly avoid initialisation.
719 sctx The current SSL CTX (inbound or outbound)
720 errstr error string pointer
722 Returns: TRUE if OK (nothing to set up, or setup worked)
726 init_ecdh(SSL_CTX * sctx, uschar ** errstr)
728 #ifdef OPENSSL_NO_ECDH
736 # ifndef EXIM_HAVE_ECDH
738 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
742 if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve, errstr))
744 if (!exp_curve || !*exp_curve)
747 /* "auto" needs to be handled carefully.
748 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
749 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
750 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
751 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
752 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
754 if (Ustrcmp(exp_curve, "auto") == 0)
756 #if OPENSSL_VERSION_NUMBER < 0x10002000L
757 DEBUG(D_tls) debug_printf(
758 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
759 exp_curve = US"prime256v1";
761 # if defined SSL_CTRL_SET_ECDH_AUTO
762 DEBUG(D_tls) debug_printf(
763 "ECDH OpenSSL 1.0.2+: temp key parameter settings: autoselection\n");
764 SSL_CTX_set_ecdh_auto(sctx, 1);
767 DEBUG(D_tls) debug_printf(
768 "ECDH OpenSSL 1.1.0+: temp key parameter settings: default selection\n");
774 DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve);
775 if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef
776 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
777 && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef
781 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve),
786 # if OPENSSL_VERSION_NUMBER < 0x30000000L
789 if (!(ecdh = EC_KEY_new_by_curve_name(nid)))
791 tls_error(US"Unable to create ec curve", NULL, NULL, errstr);
795 /* The "tmp" in the name here refers to setting a temporary key
796 not to the stability of the interface. */
798 if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0))
799 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), NULL, NULL, errstr);
801 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve);
805 #else /* v 3.0.0 + */
807 if ((rv = SSL_CTX_set1_groups(sctx, &nid, 1)) == 0)
808 tls_error(string_sprintf("Error enabling '%s' group", exp_curve), NULL, NULL, errstr);
810 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' group\n", exp_curve);
816 # endif /*EXIM_HAVE_ECDH*/
817 #endif /*OPENSSL_NO_ECDH*/
822 /*************************************************
823 * Expand key and cert file specs *
824 *************************************************/
826 #if OPENSSL_VERSION_NUMBER < 0x30000000L
829 s SSL connection (not used)
833 Returns: pointer to generated key
837 rsa_callback(SSL *s, int export, int keylength)
840 #ifdef EXIM_HAVE_RSA_GENKEY_EX
841 BIGNUM *bn = BN_new();
844 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
846 # ifdef EXIM_HAVE_RSA_GENKEY_EX
847 if ( !BN_set_word(bn, (unsigned long)RSA_F4)
848 || !(rsa_key = RSA_new())
849 || !RSA_generate_key_ex(rsa_key, keylength, bn, NULL)
852 if (!(rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL)))
856 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
857 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
863 #endif /* pre-3.0.0 */
867 /* Create and install a selfsigned certificate, for use in server mode */
868 /*XXX we could arrange to call this during prelo for a null tls_certificate option.
869 The normal cache inval + relo will suffice.
870 Just need a timer for inval. */
873 tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr)
880 DEBUG(D_tls) debug_printf("TLS: generating selfsigned server cert\n");
881 where = US"allocating pkey";
882 if (!(pkey = EVP_PKEY_new()))
885 where = US"allocating cert";
886 if (!(x509 = X509_new()))
889 where = US"generating pkey";
890 #if OPENSSL_VERSION_NUMBER < 0x30000000L
893 if (!(rsa = rsa_callback(NULL, 0, 2048)))
896 where = US"assigning pkey";
897 if (!EVP_PKEY_assign_RSA(pkey, rsa))
901 pkey = EVP_RSA_gen(2048);
904 X509_set_version(x509, 2); /* N+1 - version 3 */
905 ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
906 X509_gmtime_adj(X509_get_notBefore(x509), 0);
907 X509_gmtime_adj(X509_get_notAfter(x509), (long)2 * 60 * 60); /* 2 hour */
908 X509_set_pubkey(x509, pkey);
910 name = X509_get_subject_name(x509);
911 X509_NAME_add_entry_by_txt(name, "C",
912 MBSTRING_ASC, CUS "UK", -1, -1, 0);
913 X509_NAME_add_entry_by_txt(name, "O",
914 MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0);
915 X509_NAME_add_entry_by_txt(name, "CN",
916 MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0);
917 X509_set_issuer_name(x509, name);
919 where = US"signing cert";
920 if (!X509_sign(x509, pkey, EVP_md5()))
923 where = US"installing selfsign cert";
924 if (!SSL_CTX_use_certificate(sctx, x509))
927 where = US"installing selfsign key";
928 if (!SSL_CTX_use_PrivateKey(sctx, pkey))
934 (void) tls_error(where, NULL, NULL, errstr);
935 if (x509) X509_free(x509);
936 if (pkey) EVP_PKEY_free(pkey);
946 /*************************************************
947 * Information callback *
948 *************************************************/
950 /* The SSL library functions call this from time to time to indicate what they
951 are doing. We copy the string to the debugging output when TLS debugging has
963 info_callback(SSL * s, int where, int ret)
969 if (where & SSL_ST_CONNECT) g = string_append_listele(g, ',', US"SSL_connect");
970 if (where & SSL_ST_ACCEPT) g = string_append_listele(g, ',', US"SSL_accept");
971 if (where & SSL_CB_LOOP) g = string_append_listele(g, ',', US"state_chg");
972 if (where & SSL_CB_EXIT) g = string_append_listele(g, ',', US"hshake_exit");
973 if (where & SSL_CB_READ) g = string_append_listele(g, ',', US"read");
974 if (where & SSL_CB_WRITE) g = string_append_listele(g, ',', US"write");
975 if (where & SSL_CB_ALERT) g = string_append_listele(g, ',', US"alert");
976 if (where & SSL_CB_HANDSHAKE_START) g = string_append_listele(g, ',', US"hshake_start");
977 if (where & SSL_CB_HANDSHAKE_DONE) g = string_append_listele(g, ',', US"hshake_done");
979 if (where & SSL_CB_LOOP)
980 debug_printf("SSL %s: %s\n", g->s, SSL_state_string_long(s));
981 else if (where & SSL_CB_ALERT)
982 debug_printf("SSL %s %s:%s\n", g->s,
983 SSL_alert_type_string_long(ret), SSL_alert_desc_string_long(ret));
984 else if (where & SSL_CB_EXIT)
987 debug_printf("SSL %s: %s in %s\n", g->s,
988 ret == 0 ? "failed" : "error", SSL_state_string_long(s));
990 else if (where & (SSL_CB_HANDSHAKE_START | SSL_CB_HANDSHAKE_DONE))
991 debug_printf("SSL %s: %s\n", g->s, SSL_state_string_long(s));
995 #ifdef OPENSSL_HAVE_KEYLOG_CB
997 keylog_callback(const SSL *ssl, const char *line)
1001 DEBUG(D_tls) debug_printf("%.200s\n", line);
1002 if (!(filename = getenv("SSLKEYLOGFILE"))) return;
1003 if (!(fp = fopen(filename, "a"))) return;
1004 fprintf(fp, "%s\n", line);
1013 #ifndef DISABLE_EVENT
1015 verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
1016 BOOL *calledp, const BOOL *optionalp, const uschar * what)
1022 ev = tlsp == &tls_out ? client_static_state->event_action : event_action;
1025 DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth);
1026 old_cert = tlsp->peercert;
1027 tlsp->peercert = X509_dup(cert);
1028 /* NB we do not bother setting peerdn */
1029 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth), &errno)))
1031 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
1032 "depth=%d cert=%s: %s",
1033 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1034 what, depth, dn, yield);
1038 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
1039 return 1; /* reject (leaving peercert set) */
1041 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
1042 "(host in tls_try_verify_hosts)\n");
1043 tlsp->verify_override = TRUE;
1045 X509_free(tlsp->peercert);
1046 tlsp->peercert = old_cert;
1052 /*************************************************
1053 * Callback for verification *
1054 *************************************************/
1056 /* The SSL library does certificate verification if set up to do so. This
1057 callback has the current yes/no state is in "state". If verification succeeded,
1058 we set the certificate-verified flag. If verification failed, what happens
1059 depends on whether the client is required to present a verifiable certificate
1062 If verification is optional, we change the state to yes, but still log the
1063 verification error. For some reason (it really would help to have proper
1064 documentation of OpenSSL), this callback function then gets called again, this
1065 time with state = 1. We must take care not to set the private verified flag on
1066 the second time through.
1068 Note: this function is not called if the client fails to present a certificate
1069 when asked. We get here only if a certificate has been received. Handling of
1070 optional verification for this case is done when requesting SSL to verify, by
1071 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
1073 May be called multiple times for different issues with a certificate, even
1074 for a given "depth" in the certificate chain.
1077 preverify_ok current yes/no state as 1/0
1078 x509ctx certificate information.
1079 tlsp per-direction (client vs. server) support data
1080 calledp has-been-called flag
1081 optionalp verification-is-optional flag
1083 Returns: 0 if verification should fail, otherwise 1
1087 verify_callback(int preverify_ok, X509_STORE_CTX * x509ctx,
1088 tls_support * tlsp, BOOL * calledp, BOOL * optionalp)
1090 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
1091 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
1094 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
1096 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
1097 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1098 tlsp == &tls_out ? deliver_host_address : sender_host_address);
1101 dn[sizeof(dn)-1] = '\0';
1103 tlsp->verify_override = FALSE;
1104 if (preverify_ok == 0)
1106 uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])",
1107 *verify_mode, sender_host_address)
1109 log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
1110 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1112 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn);
1116 if (!tlsp->peercert)
1117 tlsp->peercert = X509_dup(cert); /* record failing cert */
1118 return 0; /* reject */
1120 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
1121 "tls_try_verify_hosts)\n");
1122 tlsp->verify_override = TRUE;
1125 else if (depth != 0)
1127 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
1128 #ifndef DISABLE_EVENT
1129 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
1130 return 0; /* reject, with peercert set */
1135 const uschar * verify_cert_hostnames;
1137 if ( tlsp == &tls_out
1138 && ((verify_cert_hostnames = client_static_state->verify_cert_hostnames)))
1139 /* client, wanting hostname check */
1142 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
1143 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
1144 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
1146 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
1147 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
1150 const uschar * list = verify_cert_hostnames;
1153 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
1154 if ((rc = X509_check_host(cert, CCS name, 0,
1155 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
1156 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
1161 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1162 tlsp == &tls_out ? deliver_host_address : sender_host_address);
1169 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
1172 uschar * extra = verify_mode
1173 ? string_sprintf(" (during %c-verify for [%s])",
1174 *verify_mode, sender_host_address)
1176 log_write(0, LOG_MAIN,
1177 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
1178 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1179 extra, dn, verify_cert_hostnames);
1183 if (!tlsp->peercert)
1184 tlsp->peercert = X509_dup(cert); /* record failing cert */
1185 return 0; /* reject */
1187 DEBUG(D_tls) debug_printf("SSL verify name failure overridden (host in "
1188 "tls_try_verify_hosts)\n");
1189 tlsp->verify_override = TRUE;
1193 #ifndef DISABLE_EVENT
1194 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
1195 return 0; /* reject, with peercert set */
1198 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
1199 *calledp ? "" : " authenticated", dn);
1203 return 1; /* accept, at least for this level */
1207 verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
1209 return verify_callback(preverify_ok, x509ctx, &tls_out,
1210 &client_verify_callback_called, &client_verify_optional);
1214 verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
1216 return verify_callback(preverify_ok, x509ctx, &tls_in,
1217 &server_verify_callback_called, &server_verify_optional);
1223 /* This gets called *by* the dane library verify callback, which interposes
1227 verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
1229 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
1231 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
1232 #ifndef DISABLE_EVENT
1233 BOOL dummy_called, optional = FALSE;
1236 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
1238 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
1239 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1240 deliver_host_address);
1243 dn[sizeof(dn)-1] = '\0';
1245 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
1246 preverify_ok ? "ok":"BAD", depth, dn);
1248 #ifndef DISABLE_EVENT
1249 if (verify_event(&tls_out, cert, depth, dn,
1250 &dummy_called, &optional, US"DANE"))
1251 return 0; /* reject, with peercert set */
1254 if (preverify_ok == 1)
1255 tls_out.dane_verified = TRUE;
1258 int err = X509_STORE_CTX_get_error(x509ctx);
1260 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
1261 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
1264 return preverify_ok;
1267 #endif /*SUPPORT_DANE*/
1270 #ifndef DISABLE_OCSP
1272 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
1274 BIO_printf(bp, "\t%s: ", str);
1275 ASN1_GENERALIZEDTIME_print(bp, time);
1279 /*************************************************
1280 * Load OCSP information into state *
1281 *************************************************/
1282 /* Called to load the server OCSP response from the given file into memory, once
1283 caller has determined this is needed. Checks validity. Debugs a message
1286 ASSUMES: single response, for single cert.
1289 state various parts of session state
1290 filename the filename putatively holding an OCSP response
1291 is_pem file is PEM format; otherwise is DER
1295 ocsp_load_response(exim_openssl_state_st * state, const uschar * filename,
1299 OCSP_RESPONSE * resp;
1300 OCSP_BASICRESP * basic_response;
1301 OCSP_SINGLERESP * single_response;
1302 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
1303 STACK_OF(X509) * sk;
1304 int status, reason, i;
1307 debug_printf("tls_ocsp_file (%s) '%s'\n", is_pem ? "PEM" : "DER", filename);
1309 if (!filename || !*filename) return;
1312 if (!(bio = BIO_new_file(CS filename, "rb")))
1314 log_write(0, LOG_MAIN|LOG_PANIC,
1315 "Failed to open OCSP response file \"%s\": %.100s",
1316 filename, ERR_reason_error_string(ERR_get_error()));
1322 uschar * data, * freep;
1325 if (!PEM_read_bio(bio, &dummy, &dummy, &data, &len))
1327 log_write(0, LOG_MAIN|LOG_PANIC, "Failed to read PEM file \"%s\": %.100s",
1328 filename, ERR_reason_error_string(ERR_get_error()));
1332 resp = d2i_OCSP_RESPONSE(NULL, CUSS &data, len);
1333 OPENSSL_free(freep);
1336 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
1341 log_write(0, LOG_MAIN|LOG_PANIC, "Error reading OCSP response from \"%s\": %s",
1342 filename, ERR_reason_error_string(ERR_get_error()));
1346 if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
1348 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
1349 OCSP_response_status_str(status), status);
1355 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1356 OCSP_RESPONSE_print(bp, resp, 0); /* extreme debug: stapling content */
1361 if (!(basic_response = OCSP_response_get1_basic(resp)))
1364 debug_printf("OCSP response parse error: unable to extract basic response.\n");
1368 sk = state->u_ocsp.server.verify_stack; /* set by setup_certs() / chain_from_pem_file() */
1370 /* May need to expose ability to adjust those flags?
1371 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
1372 OCSP_TRUSTOTHER OCSP_NOINTERN */
1374 /* This does a partial verify (only the signer link, not the whole chain-to-CA)
1375 on the OCSP proof before we load it for serving up; possibly overkill -
1376 just date-checks might be nice enough.
1378 OCSP_basic_verify takes a "store" arg, but does not
1379 use it for the chain verification, when OCSP_NOVERIFY is set.
1380 The content from the wire "basic_response" and a cert-stack "sk" are all
1383 We have a stack, loaded in setup_certs() if tls_verify_certificates
1384 was a file (not a directory, or "system"). It is unfortunate we
1385 cannot used the connection context store, as that would neatly
1386 handle the "system" case too, but there seems to be no library
1387 function for getting a stack from a store.
1388 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
1389 [ 3.0.0 - sk = X509_STORE_get1_all_certs(store) ]
1390 We do not free the stack since it could be needed a second time for
1393 Separately we might try to replace using OCSP_basic_verify() - which seems to not
1394 be a public interface into the OpenSSL library (there's no manual entry) -
1395 (in 3.0.0 + is is public)
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, OCSP_NOVERIFY)) < 0)
1404 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1405 debug_printf("OCSP response has bad signature: %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))
1441 BIO * bp = BIO_new(BIO_s_mem());
1444 time_print(bp, "This OCSP Update", thisupd);
1445 if (nextupd) time_print(bp, "Next OCSP Update", nextupd);
1446 if ((len = (int) BIO_get_mem_data(bp, CSS &s)) > 0) debug_printf("%.*s", len, s);
1447 debug_printf("OCSP status invalid times.\n");
1453 /* Add the resp to the list used by tls_server_stapling_cb() */
1455 ocsp_resplist ** op = &state->u_ocsp.server.olist, * oentry;
1456 while (oentry = *op)
1458 *op = oentry = store_get(sizeof(ocsp_resplist), GET_UNTAINTED);
1459 oentry->next = NULL;
1460 oentry->resp = resp;
1465 if (f.running_in_test_harness)
1467 extern char ** environ;
1468 if (environ) for (uschar ** p = USS environ; *p; p++)
1469 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1471 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
1472 goto supply_response;
1480 ocsp_free_response_list(exim_openssl_state_st * state)
1482 for (ocsp_resplist * olist = state->u_ocsp.server.olist; olist;
1483 olist = olist->next)
1484 OCSP_RESPONSE_free(olist->resp);
1485 state->u_ocsp.server.olist = NULL;
1487 #endif /*!DISABLE_OCSP*/
1494 tls_add_certfile(SSL_CTX * sctx, exim_openssl_state_st * cbinfo, uschar * file,
1497 DEBUG(D_tls) debug_printf("tls_certificate file '%s'\n", file);
1498 if (!SSL_CTX_use_certificate_chain_file(sctx, CS file))
1499 return tls_error(string_sprintf(
1500 "SSL_CTX_use_certificate_chain_file file=%s", file),
1501 cbinfo->host, NULL, errstr);
1506 tls_add_pkeyfile(SSL_CTX * sctx, exim_openssl_state_st * cbinfo, uschar * file,
1509 DEBUG(D_tls) debug_printf("tls_privatekey file '%s'\n", file);
1510 if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM))
1511 return tls_error(string_sprintf(
1512 "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr);
1519 /* Called once during tls_init and possibly again during TLS setup, for a
1520 new context, if Server Name Indication was used and tls_sni was seen in
1521 the certificate string.
1524 sctx the SSL_CTX* to update
1525 state various parts of session state
1526 errstr error string pointer
1528 Returns: OK/DEFER/FAIL
1532 tls_expand_session_files(SSL_CTX * sctx, exim_openssl_state_st * state,
1537 if (!state->certificate)
1539 if (!state->is_server) /* client */
1542 if (tls_install_selfsign(sctx, errstr) != OK)
1549 if ( !reexpand_tls_files_for_sni
1550 && ( Ustrstr(state->certificate, US"tls_sni")
1551 || Ustrstr(state->certificate, US"tls_in_sni")
1552 || Ustrstr(state->certificate, US"tls_out_sni")
1554 reexpand_tls_files_for_sni = TRUE;
1556 if (!expand_check(state->certificate, US"tls_certificate", &expanded, errstr))
1560 if (state->is_server)
1562 const uschar * file_list = expanded;
1565 #ifndef DISABLE_OCSP
1566 const uschar * olist = state->u_ocsp.server.file;
1569 BOOL fmt_pem = FALSE;
1572 if (!expand_check(olist, US"tls_ocsp_file", USS &olist, errstr))
1574 if (olist && !*olist)
1577 /* If doing a re-expand after SNI, avoid reloading the OCSP
1578 responses when the list of filenames has not changed.
1579 The creds-invali on content change wipes file_expanded, so that
1580 always reloads here. */
1582 if ( state->u_ocsp.server.file_expanded && olist
1583 && (Ustrcmp(olist, state->u_ocsp.server.file_expanded) == 0))
1585 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
1590 ocsp_free_response_list(state);
1591 state->u_ocsp.server.file_expanded = olist;
1595 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1597 if ((err = tls_add_certfile(sctx, state, file, errstr)))
1600 #ifndef DISABLE_OCSP
1602 if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1604 if (Ustrncmp(ofile, US"PEM ", 4) == 0)
1609 else if (Ustrncmp(ofile, US"DER ", 4) == 0)
1614 ocsp_load_response(state, ofile, fmt_pem);
1617 DEBUG(D_tls) debug_printf("ran out of ocsp file list\n");
1621 else /* would there ever be a need for multiple client certs? */
1622 if ((err = tls_add_certfile(sctx, state, expanded, errstr)))
1625 if ( state->privatekey
1626 && !expand_check(state->privatekey, US"tls_privatekey", &expanded, errstr))
1629 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1630 of the expansion is an empty string, ignore it also, and assume the private
1631 key is in the same file as the certificate. */
1633 if (expanded && *expanded)
1634 if (state->is_server)
1636 const uschar * file_list = expanded;
1640 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1641 if ((err = tls_add_pkeyfile(sctx, state, file, errstr)))
1644 else /* would there ever be a need for multiple client certs? */
1645 if ((err = tls_add_pkeyfile(sctx, state, expanded, errstr)))
1655 /**************************************************
1656 * One-time init credentials for server and client *
1657 **************************************************/
1660 normalise_ciphers(uschar ** ciphers, const uschar * pre_expansion_ciphers)
1662 uschar * s = *ciphers;
1664 if (!s || !Ustrchr(s, '_')) return; /* no change needed */
1666 if (s == pre_expansion_ciphers)
1667 s = string_copy(s); /* get writable copy */
1669 for (uschar * t = s; *t; t++) if (*t == '_') *t = '-';
1674 server_load_ciphers(SSL_CTX * ctx, exim_openssl_state_st * state,
1675 uschar * ciphers, uschar ** errstr)
1677 DEBUG(D_tls) debug_printf("required ciphers: %s\n", ciphers);
1678 if (!SSL_CTX_set_cipher_list(ctx, CS ciphers))
1679 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
1680 state->server_cipher_list = ciphers;
1687 lib_ctx_new(SSL_CTX ** ctxp, host_item * host, uschar ** errstr)
1690 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1691 if (!(ctx = SSL_CTX_new(host ? TLS_client_method() : TLS_server_method())))
1693 if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
1695 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
1697 /* Set up the information callback, which outputs if debugging is at a suitable
1702 SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
1703 #if defined(EXIM_HAVE_OPESSL_TRACE) && !defined(OPENSSL_NO_SSL_TRACE)
1704 /* this needs a debug build of OpenSSL */
1705 SSL_CTX_set_msg_callback(ctx, (void (*)())SSL_trace);
1707 #ifdef OPENSSL_HAVE_KEYLOG_CB
1708 SSL_CTX_set_keylog_callback(ctx, (void (*)())keylog_callback);
1712 /* Automatically re-try reads/writes after renegotiation. */
1713 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
1720 tls_server_creds_init(void)
1723 uschar * dummy_errstr;
1724 unsigned lifetime = 0;
1728 state_server.lib_state = null_tls_preload;
1730 if (lib_ctx_new(&ctx, NULL, &dummy_errstr) != OK)
1732 state_server.lib_state.lib_ctx = ctx;
1734 /* Preload DH params and EC curve */
1736 if (opt_unset_or_noexpand(tls_dhparam))
1738 DEBUG(D_tls) debug_printf("TLS: preloading DH params for server\n");
1739 if (init_dh(ctx, tls_dhparam, &dummy_errstr))
1740 state_server.lib_state.dh = TRUE;
1743 DEBUG(D_tls) debug_printf("TLS: not preloading DH params for server\n");
1744 if (opt_unset_or_noexpand(tls_eccurve))
1746 DEBUG(D_tls) debug_printf("TLS: preloading ECDH curve for server\n");
1747 if (init_ecdh(ctx, &dummy_errstr))
1748 state_server.lib_state.ecdh = TRUE;
1751 DEBUG(D_tls) debug_printf("TLS: not preloading ECDH curve for server\n");
1753 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1754 /* If we can, preload the Authorities for checking client certs against.
1755 Actual choice to do verify is made (tls_{,try_}verify_hosts)
1756 at TLS conn startup.
1757 Do this before the server ocsp so that its info can verify the ocsp. */
1759 if ( opt_set_and_noexpand(tls_verify_certificates)
1760 && opt_unset_or_noexpand(tls_crl))
1762 /* Watch the default dir also as they are always included */
1764 if ( tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
1765 && tls_set_watch(tls_verify_certificates, FALSE)
1766 && tls_set_watch(tls_crl, FALSE))
1768 uschar * v_certs = tls_verify_certificates;
1769 DEBUG(D_tls) debug_printf("TLS: preloading CA bundle for server\n");
1771 if (setup_certs(ctx, &v_certs, tls_crl, NULL, &dummy_errstr) == OK)
1772 state_server.lib_state.cabundle = TRUE;
1774 /* If we can, preload the server-side cert, key and ocsp */
1776 if ( opt_set_and_noexpand(tls_certificate)
1777 # ifndef DISABLE_OCSP
1778 && opt_unset_or_noexpand(tls_ocsp_file)
1780 && opt_unset_or_noexpand(tls_privatekey))
1782 /* Set watches on the filenames. The implementation does de-duplication
1783 so we can just blindly do them all. */
1785 if ( tls_set_watch(tls_certificate, TRUE)
1786 # ifndef DISABLE_OCSP
1787 && tls_set_watch(tls_ocsp_file, TRUE)
1789 && tls_set_watch(tls_privatekey, TRUE))
1791 state_server.certificate = tls_certificate;
1792 state_server.privatekey = tls_privatekey;
1793 #ifndef DISABLE_OCSP
1794 state_server.u_ocsp.server.file = tls_ocsp_file;
1797 DEBUG(D_tls) debug_printf("TLS: preloading server certs\n");
1798 if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
1799 state_server.lib_state.conn_certs = TRUE;
1802 else if ( !tls_certificate && !tls_privatekey
1803 # ifndef DISABLE_OCSP
1807 { /* Generate & preload a selfsigned cert. No files to watch. */
1808 if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
1810 state_server.lib_state.conn_certs = TRUE;
1811 lifetime = f.running_in_test_harness ? 2 : 60 * 60; /* 1 hour */
1815 DEBUG(D_tls) debug_printf("TLS: not preloading server certs\n");
1819 DEBUG(D_tls) debug_printf("TLS: not preloading CA bundle for server\n");
1822 #endif /* EXIM_HAVE_INOTIFY */
1825 /* If we can, preload the ciphers control string */
1827 if (opt_set_and_noexpand(tls_require_ciphers))
1829 DEBUG(D_tls) debug_printf("TLS: preloading cipher list for server\n");
1830 normalise_ciphers(&tls_require_ciphers, tls_require_ciphers);
1831 if (server_load_ciphers(ctx, &state_server, tls_require_ciphers,
1832 &dummy_errstr) == OK)
1833 state_server.lib_state.pri_string = TRUE;
1836 DEBUG(D_tls) debug_printf("TLS: not preloading cipher list for server\n");
1843 /* Preload whatever creds are static, onto a transport. The client can then
1844 just copy the pointer as it starts up.
1845 Called from the daemon after a cache-invalidate with watch set; called from
1846 a queue-run startup with watch clear. */
1849 tls_client_creds_init(transport_instance * t, BOOL watch)
1851 smtp_transport_options_block * ob = t->options_block;
1852 exim_openssl_state_st tpt_dummy_state;
1853 host_item * dummy_host = (host_item *)1;
1854 uschar * dummy_errstr;
1859 ob->tls_preload = null_tls_preload;
1860 if (lib_ctx_new(&ctx, dummy_host, &dummy_errstr) != OK)
1862 ob->tls_preload.lib_ctx = ctx;
1864 tpt_dummy_state.lib_state = ob->tls_preload;
1866 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1867 if ( opt_set_and_noexpand(ob->tls_certificate)
1868 && opt_unset_or_noexpand(ob->tls_privatekey))
1871 || ( tls_set_watch(ob->tls_certificate, FALSE)
1872 && tls_set_watch(ob->tls_privatekey, FALSE)
1875 uschar * pkey = ob->tls_privatekey;
1878 debug_printf("TLS: preloading client certs for transport '%s'\n",t->name);
1880 if ( tls_add_certfile(ctx, &tpt_dummy_state, ob->tls_certificate,
1882 && tls_add_pkeyfile(ctx, &tpt_dummy_state,
1883 pkey ? pkey : ob->tls_certificate,
1886 ob->tls_preload.conn_certs = TRUE;
1891 debug_printf("TLS: not preloading client certs, for transport '%s'\n", t->name);
1894 if ( opt_set_and_noexpand(ob->tls_verify_certificates)
1895 && opt_unset_or_noexpand(ob->tls_crl))
1898 || tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
1899 && tls_set_watch(ob->tls_verify_certificates, FALSE)
1900 && tls_set_watch(ob->tls_crl, FALSE)
1903 uschar * v_certs = ob->tls_verify_certificates;
1905 debug_printf("TLS: preloading CA bundle for transport '%s'\n", t->name);
1907 if (setup_certs(ctx, &v_certs,
1908 ob->tls_crl, dummy_host, &dummy_errstr) == OK)
1909 ob->tls_preload.cabundle = TRUE;
1914 debug_printf("TLS: not preloading CA bundle, for transport '%s'\n", t->name);
1916 #endif /*EXIM_HAVE_INOTIFY*/
1920 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1921 /* Invalidate the creds cached, by dropping the current ones.
1922 Call when we notice one of the source files has changed. */
1925 tls_server_creds_invalidate(void)
1927 SSL_CTX_free(state_server.lib_state.lib_ctx);
1928 state_server.lib_state = null_tls_preload;
1929 #ifndef DISABLE_OCSP
1930 state_server.u_ocsp.server.file_expanded = NULL;
1936 tls_client_creds_invalidate(transport_instance * t)
1938 smtp_transport_options_block * ob = t->options_block;
1939 SSL_CTX_free(ob->tls_preload.lib_ctx);
1940 ob->tls_preload = null_tls_preload;
1946 tls_server_creds_invalidate(void)
1950 tls_client_creds_invalidate(transport_instance * t)
1953 #endif /*EXIM_HAVE_INOTIFY*/
1958 #ifndef DISABLE_OCSP
1960 debug_print_sn(const X509 * cert)
1962 X509_NAME * sn = X509_get_subject_name((X509 *)cert);
1963 static uschar name[256];
1964 if (X509_NAME_oneline(sn, CS name, sizeof(name)))
1966 name[sizeof(name)-1] = '\0';
1967 debug_printf(" %s\n", name);
1972 x509_stack_dump_cert_s_names(const STACK_OF(X509) * sk)
1975 debug_printf(" (null)\n");
1978 int idx = sk_X509_num(sk);
1980 debug_printf(" (empty)\n");
1982 while (--idx >= 0) debug_print_sn(sk_X509_value(sk, idx));
1987 x509_store_dump_cert_s_names(X509_STORE * store)
1989 # ifdef EXIM_HAVE_OPENSSL_X509_STORE_GET1_ALL_CERTS
1991 debug_printf(" (no store)\n");
1994 STACK_OF(X509) * sk = X509_STORE_get1_all_certs(store);
1995 x509_stack_dump_cert_s_names(sk);
1996 sk_X509_pop_free(sk, X509_free);
2000 #endif /*!DISABLE_OCSP*/
2005 #ifndef DISABLE_TLS_RESUME
2006 /* Manage the keysets used for encrypting the session tickets, on the server. */
2008 typedef struct { /* Session ticket encryption key */
2011 const EVP_CIPHER * aes_cipher;
2012 uschar aes_key[32]; /* size needed depends on cipher. aes_128 implies 128/8 = 16? */
2013 # if OPENSSL_VERSION_NUMBER < 0x30000000L
2014 const EVP_MD * hmac_hash;
2016 const uschar * hmac_hashname;
2018 uschar hmac_key[16];
2023 static exim_stek exim_tk; /* current key */
2024 static exim_stek exim_tk_old; /* previous key */
2029 time_t t = time(NULL);
2031 if (exim_tk.name[0])
2033 if (exim_tk.renew >= t) return;
2034 exim_tk_old = exim_tk;
2037 if (f.running_in_test_harness) ssl_session_timeout = 6;
2039 DEBUG(D_tls) debug_printf("OpenSSL: %s STEK\n", exim_tk.name[0] ? "rotating" : "creating");
2040 if (RAND_bytes(exim_tk.aes_key, sizeof(exim_tk.aes_key)) <= 0) return;
2041 if (RAND_bytes(exim_tk.hmac_key, sizeof(exim_tk.hmac_key)) <= 0) return;
2042 if (RAND_bytes(exim_tk.name+1, sizeof(exim_tk.name)-1) <= 0) return;
2044 exim_tk.name[0] = 'E';
2045 exim_tk.aes_cipher = EVP_aes_256_cbc();
2046 # if OPENSSL_VERSION_NUMBER < 0x30000000L
2047 exim_tk.hmac_hash = EVP_sha256();
2049 exim_tk.hmac_hashname = US "sha256";
2051 exim_tk.expire = t + ssl_session_timeout;
2052 exim_tk.renew = t + ssl_session_timeout/2;
2058 if (!exim_tk.name[0]) return NULL;
2063 tk_find(const uschar * name)
2065 return memcmp(name, exim_tk.name, sizeof(exim_tk.name)) == 0 ? &exim_tk
2066 : memcmp(name, exim_tk_old.name, sizeof(exim_tk_old.name)) == 0 ? &exim_tk_old
2073 # if OPENSSL_VERSION_NUMBER < 0x30000000L
2081 /*XXX will want these dependent on the ssl session strength */
2082 # if OPENSSL_VERSION_NUMBER < 0x30000000L
2083 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
2084 key->hmac_hash, NULL);
2087 OSSL_PARAM params[3];
2088 uschar * hk = string_copy(key->hmac_hashname); /* need nonconst */
2089 params[0] = OSSL_PARAM_construct_octet_string("key", key->hmac_key, sizeof(key->hmac_key));
2090 params[1] = OSSL_PARAM_construct_utf8_string("digest", CS hk, 0);
2091 params[2] = OSSL_PARAM_construct_end();
2092 if (EVP_MAC_CTX_set_params(hctx, params) == 0)
2094 DEBUG(D_tls) debug_printf("EVP_MAC_CTX_set_params: %s\n",
2095 ERR_reason_error_string(ERR_get_error()));
2096 return 0; /* error in mac initialisation */
2103 /* Callback for session tickets, on server */
2105 ticket_key_callback(SSL * ssl, uschar key_name[16],
2106 uschar * iv, EVP_CIPHER_CTX * c_ctx,
2107 # if OPENSSL_VERSION_NUMBER < 0x30000000L
2114 tls_support * tlsp = state_server.tlsp;
2119 DEBUG(D_tls) debug_printf("ticket_key_callback: create new session\n");
2120 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
2122 if (RAND_bytes(iv, EVP_MAX_IV_LENGTH) <= 0)
2123 return -1; /* insufficient random */
2125 if (!(key = tk_current())) /* current key doesn't exist or isn't valid */
2126 return 0; /* key couldn't be created */
2127 memcpy(key_name, key->name, 16);
2128 DEBUG(D_tls) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - time(NULL));
2130 if (tk_hmac_init(hctx, key) == 0) return 0;
2131 EVP_EncryptInit_ex(c_ctx, key->aes_cipher, NULL, key->aes_key, iv);
2133 DEBUG(D_tls) debug_printf("ticket created\n");
2138 time_t now = time(NULL);
2140 DEBUG(D_tls) debug_printf("ticket_key_callback: retrieve session\n");
2141 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
2143 if (!(key = tk_find(key_name)) || key->expire < now)
2147 debug_printf("ticket not usable (%s)\n", key ? "expired" : "not found");
2148 if (key) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - now);
2153 if (tk_hmac_init(hctx, key) == 0) return 0;
2154 EVP_DecryptInit_ex(c_ctx, key->aes_cipher, NULL, key->aes_key, iv);
2156 DEBUG(D_tls) debug_printf("ticket usable, STEK expire " TIME_T_FMT "\n", key->expire - now);
2158 /* The ticket lifetime and renewal are the same as the STEK lifetime and
2159 renewal, which is overenthusiastic. A factor of, say, 3x longer STEK would
2160 be better. To do that we'd have to encode ticket lifetime in the name as
2161 we don't yet see the restored session. Could check posthandshake for TLS1.3
2162 and trigger a new ticket then, but cannot do that for TLS1.2 */
2163 return key->renew < now ? 2 : 1;
2166 #endif /* !DISABLE_TLS_RESUME */
2171 setup_cert_verify(SSL_CTX * ctx, BOOL optional,
2172 int (*cert_vfy_cb)(int, X509_STORE_CTX *))
2174 /* If verification is optional, don't fail if no certificate */
2176 SSL_CTX_set_verify(ctx,
2177 SSL_VERIFY_PEER | (optional ? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
2182 /*************************************************
2183 * Callback to handle SNI *
2184 *************************************************/
2186 /* Called when acting as server during the TLS session setup if a Server Name
2187 Indication extension was sent by the client.
2189 API documentation is OpenSSL s_server.c implementation.
2192 s SSL* of the current session
2193 ad unknown (part of OpenSSL API) (unused)
2194 arg Callback of "our" registered data
2196 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
2198 XXX might need to change to using ClientHello callback,
2199 per https://www.openssl.org/docs/manmaster/man3/SSL_client_hello_cb_fn.html
2202 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2204 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
2206 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
2207 exim_openssl_state_st *state = (exim_openssl_state_st *) arg;
2209 int old_pool = store_pool;
2210 uschar * dummy_errstr;
2213 return SSL_TLSEXT_ERR_OK;
2215 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
2216 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
2218 /* Make the extension value available for expansion */
2219 store_pool = POOL_PERM;
2220 tls_in.sni = string_copy_taint(US servername, GET_TAINTED);
2221 store_pool = old_pool;
2223 if (!reexpand_tls_files_for_sni)
2224 return SSL_TLSEXT_ERR_OK;
2226 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
2227 not confident that memcpy wouldn't break some internal reference counting.
2228 Especially since there's a references struct member, which would be off. */
2230 if (lib_ctx_new(&server_sni, NULL, &dummy_errstr) != OK)
2233 /* Not sure how many of these are actually needed, since SSL object
2234 already exists. Might even need this selfsame callback, for reneg? */
2237 SSL_CTX * ctx = state_server.lib_state.lib_ctx;
2238 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(ctx));
2239 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(ctx));
2240 #ifdef OPENSSL_MIN_PROTO_VERSION
2241 SSL_CTX_set_min_proto_version(server_sni, SSL3_VERSION);
2243 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(ctx));
2244 SSL_CTX_clear_options(server_sni, ~SSL_CTX_get_options(ctx));
2245 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(ctx));
2246 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
2247 SSL_CTX_set_tlsext_servername_arg(server_sni, state);
2250 if ( !init_dh(server_sni, state->dhparam, &dummy_errstr)
2251 || !init_ecdh(server_sni, &dummy_errstr)
2255 if ( state->server_cipher_list
2256 && !SSL_CTX_set_cipher_list(server_sni, CS state->server_cipher_list))
2259 #ifndef DISABLE_OCSP
2260 if (state->u_ocsp.server.file)
2262 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
2263 SSL_CTX_set_tlsext_status_arg(server_sni, state);
2268 uschar * v_certs = tls_verify_certificates;
2269 if ((rc = setup_certs(server_sni, &v_certs, tls_crl, NULL,
2270 &dummy_errstr)) != OK)
2273 if (v_certs && *v_certs)
2274 setup_cert_verify(server_sni, FALSE, verify_callback_server);
2277 /* do this after setup_certs, because this can require the certs for verifying
2278 OCSP information. */
2279 if ((rc = tls_expand_session_files(server_sni, state, &dummy_errstr)) != OK)
2282 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
2283 SSL_set_SSL_CTX(s, server_sni);
2284 return SSL_TLSEXT_ERR_OK;
2286 bad: return SSL_TLSEXT_ERR_ALERT_FATAL;
2288 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
2293 #ifdef EXIM_HAVE_ALPN
2294 /*************************************************
2295 * Callback to handle ALPN *
2296 *************************************************/
2298 /* Called on server if tls_alpn nonblank after expansion,
2299 when client offers ALPN, after the SNI callback.
2300 If set and not matching the list then we dump the connection */
2303 tls_server_alpn_cb(SSL *ssl, const uschar ** out, uschar * outlen,
2304 const uschar * in, unsigned int inlen, void * arg)
2306 server_seen_alpn = TRUE;
2309 debug_printf("Received TLS ALPN offer:");
2310 for (int pos = 0, siz; pos < inlen; pos += siz+1)
2313 if (pos + 1 + siz > inlen) siz = inlen - pos - 1;
2314 debug_printf(" '%.*s'", siz, in + pos + 1);
2316 debug_printf(". Our list: '%s'\n", tls_alpn);
2319 /* Look for an acceptable ALPN */
2321 if ( inlen > 1 /* at least one name */
2322 && in[0]+1 == inlen /* filling the vector, so exactly one name */
2325 const uschar * list = tls_alpn;
2327 for (uschar * name; name = string_nextinlist(&list, &sep, NULL, 0); )
2328 if (Ustrncmp(in+1, name, in[0]) == 0)
2330 *out = in+1; /* we checked for exactly one, so can just point to it */
2332 return SSL_TLSEXT_ERR_OK; /* use ALPN */
2336 /* More than one name from clilent, or name did not match our list. */
2338 /* This will be fatal to the TLS conn; would be nice to kill TCP also.
2339 Maybe as an option in future; for now leave control to the config (must-tls). */
2341 DEBUG(D_tls) debug_printf("TLS ALPN rejected\n");
2342 return SSL_TLSEXT_ERR_ALERT_FATAL;
2344 #endif /* EXIM_HAVE_ALPN */
2348 #ifndef DISABLE_OCSP
2350 /*************************************************
2351 * Callback to handle OCSP Stapling *
2352 *************************************************/
2354 /* Called when acting as server during the TLS session setup if the client
2355 requests OCSP information with a Certificate Status Request.
2357 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
2363 tls_server_stapling_cb(SSL *s, void *arg)
2365 const exim_openssl_state_st * state = arg;
2366 ocsp_resplist * olist = state->u_ocsp.server.olist;
2367 uschar * response_der; /*XXX blob */
2368 int response_der_len;
2371 debug_printf("Received TLS status request (OCSP stapling); %s response list\n",
2372 olist ? "have" : "lack");
2374 tls_in.ocsp = OCSP_NOT_RESP;
2376 return SSL_TLSEXT_ERR_NOACK;
2378 #ifdef EXIM_HAVE_OPESSL_GET0_SERIAL
2380 const X509 * cert_sent = SSL_get_certificate(s);
2381 const ASN1_INTEGER * cert_serial = X509_get0_serialNumber(cert_sent);
2382 const BIGNUM * cert_bn = ASN1_INTEGER_to_BN(cert_serial, NULL);
2384 for (; olist; olist = olist->next)
2386 OCSP_BASICRESP * bs = OCSP_response_get1_basic(olist->resp);
2387 const OCSP_SINGLERESP * single = OCSP_resp_get0(bs, 0);
2388 const OCSP_CERTID * cid = OCSP_SINGLERESP_get0_id(single);
2389 ASN1_INTEGER * res_cert_serial;
2390 const BIGNUM * resp_bn;
2391 ASN1_OCTET_STRING * res_cert_iNameHash;
2394 (void) OCSP_id_get0_info(&res_cert_iNameHash, NULL, NULL, &res_cert_serial,
2395 (OCSP_CERTID *) cid);
2396 resp_bn = ASN1_INTEGER_to_BN(res_cert_serial, NULL);
2400 debug_printf("cert serial: %s\n", BN_bn2hex(cert_bn));
2401 debug_printf("resp serial: %s\n", BN_bn2hex(resp_bn));
2404 if (BN_cmp(cert_bn, resp_bn) == 0)
2406 DEBUG(D_tls) debug_printf("matched serial for ocsp\n");
2408 /*XXX TODO: check the rest of the list for duplicate matches.
2409 If any, need to also check the Issuer Name hash.
2410 Without this, we will provide the wrong status in the case of
2415 DEBUG(D_tls) debug_printf("not match serial for ocsp\n");
2419 DEBUG(D_tls) debug_printf("failed to find match for ocsp\n");
2420 return SSL_TLSEXT_ERR_NOACK;
2426 DEBUG(D_tls) debug_printf("OpenSSL version too early to support multi-leaf OCSP\n");
2427 return SSL_TLSEXT_ERR_NOACK;
2431 /*XXX could we do the i2d earlier, rather than during the callback? */
2432 response_der = NULL;
2433 response_der_len = i2d_OCSP_RESPONSE(olist->resp, &response_der);
2434 if (response_der_len <= 0)
2435 return SSL_TLSEXT_ERR_NOACK;
2437 SSL_set_tlsext_status_ocsp_resp(state_server.lib_state.lib_ssl,
2438 response_der, response_der_len);
2439 tls_in.ocsp = OCSP_VFIED;
2440 return SSL_TLSEXT_ERR_OK;
2445 add_chain_to_store(X509_STORE * store, STACK_OF(X509) * sk,
2446 const char * debug_text)
2452 debug_printf("chain for %s:\n", debug_text);
2453 x509_stack_dump_cert_s_names(sk);
2456 if ((idx = sk_X509_num(sk)) > 0)
2458 X509_STORE_add_cert(store, sk_X509_value(sk, idx));
2463 tls_client_stapling_cb(SSL * ssl, void * arg)
2465 exim_openssl_state_st * cbinfo = arg;
2466 const unsigned char * p;
2468 OCSP_RESPONSE * rsp;
2469 OCSP_BASICRESP * bs;
2472 DEBUG(D_tls) debug_printf("Received TLS status callback (OCSP stapling):\n");
2473 len = SSL_get_tlsext_status_ocsp_resp(ssl, &p);
2475 { /* Expect this when we requested ocsp but got none */
2476 if (SSL_session_reused(ssl) && tls_out.ocsp == OCSP_VFIED)
2478 DEBUG(D_tls) debug_printf(" null, but resumed; ocsp vfy stored with session is good\n");
2482 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
2483 log_write(0, LOG_MAIN, "Required TLS certificate status not received");
2485 DEBUG(D_tls) debug_printf(" null\n");
2487 if (!cbinfo->u_ocsp.client.verify_required)
2489 cbinfo->u_ocsp.client.verify_errstr =
2490 US"(SSL_connect) Required TLS certificate status not received";
2494 if (!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
2496 tls_out.ocsp = OCSP_FAILED; /*XXX should use tlsp-> to permit concurrent outbound */
2497 if (LOGGING(tls_cipher))
2498 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
2500 DEBUG(D_tls) debug_printf(" parse error\n");
2504 if (!(bs = OCSP_response_get1_basic(rsp)))
2506 tls_out.ocsp = OCSP_FAILED;
2507 if (LOGGING(tls_cipher))
2508 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
2510 DEBUG(D_tls) debug_printf(" error parsing response\n");
2511 OCSP_RESPONSE_free(rsp);
2515 /* We'd check the nonce here if we'd put one in the request. */
2516 /* However that would defeat cacheability on the server so we don't. */
2518 /* This section of code reworked from OpenSSL apps source;
2519 The OpenSSL Project retains copyright:
2520 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
2524 X509_STORE * verify_store = NULL;
2525 BOOL have_verified_OCSP_signer = FALSE;
2526 #ifndef EXIM_HAVE_OCSP_RESP_COUNT
2527 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
2530 DEBUG(D_tls) bp = BIO_new(BIO_s_mem());
2532 /* Use the CA & chain that verified the server cert to verify the stapled info */
2533 /*XXX could we do an event here, for observability of ocsp? What reasonable data could we give access to? */
2534 /* Dates would be a start. Do we need another opaque variable type, as for certs, plus an extract expansion? */
2537 /* If this routine is not available, we've avoided [in tls_client_start()]
2538 asking for certificate-status under DANE, so this callback won't run for
2539 that combination. It still will for non-DANE. */
2541 #ifdef EXIM_HAVE_OPENSSL_OCSP_RESP_GET0_SIGNER
2544 if ( tls_out.dane_verified
2545 && (have_verified_OCSP_signer =
2546 OCSP_resp_get0_signer(bs, &signer, SSL_get0_verified_chain(ssl)) == 1))
2549 debug_printf("signer for OCSP basicres is in the verified chain;"
2550 " shortcut its verification\n");
2555 STACK_OF(X509) * verified_chain;
2557 verify_store = X509_STORE_new();
2559 SSL_get0_chain_certs(ssl, &verified_chain);
2560 add_chain_to_store(verify_store, verified_chain,
2561 "'current cert' per SSL_get0_chain_certs()");
2562 #ifdef EXIM_HAVE_SSL_GET0_VERIFIED_CHAIN
2563 verified_chain = SSL_get0_verified_chain(ssl);
2564 add_chain_to_store(verify_store, verified_chain,
2565 "SSL_get0_verified_chain()");
2572 debug_printf("Untrusted intermediate cert stack (from SSL_get_peer_cert_chain()):\n");
2573 x509_stack_dump_cert_s_names(SSL_get_peer_cert_chain(ssl));
2575 debug_printf("will use this CA store for verifying basicresp:\n");
2576 x509_store_dump_cert_s_names(verify_store);
2578 /* OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
2580 debug_printf("certs contained in basicresp:\n");
2581 x509_stack_dump_cert_s_names(
2582 #ifdef EXIM_HAVE_OPESSL_OCSP_RESP_GET0_CERTS
2583 OCSP_resp_get0_certs(bs)
2589 #ifdef EXIM_HAVE_OPENSSL_X509_STORE_GET1_ALL_CERTS
2590 /* could do via X509_STORE_get0_objects(); not worth it just for debug info */
2593 if (OCSP_resp_get0_signer(bs, &signer, X509_STORE_get1_all_certs(verify_store)) == 1)
2595 debug_printf("found signer for basicres:\n");
2596 debug_print_sn(signer);
2600 debug_printf("failed to find signer for basicres:\n");
2601 ERR_print_errors(bp);
2610 /* Under DANE the trust-anchor (at least in TA mode) is indicated by the TLSA
2611 record in DNS, and probably is not the root of the chain of certificates. So
2612 accept a partial chain for that case (and hope that anchor is visible for
2613 verifying the OCSP stapling).
2614 XXX for EE mode it won't even be that. Does that make OCSP useless for EE?
2616 Worse, for LetsEncrypt-mode (ocsp signer is leaf-signer) under DANE, the
2617 data used within OpenSSL for the signer has nil pointers for signing
2618 algorithms - and a crash results. Avoid this by shortcutting verification,
2619 having determined that the OCSP signer is in the (DANE-)validated set.
2622 #ifndef OCSP_PARTIAL_CHAIN /* defined for 3.0.0 onwards */
2623 # define OCSP_PARTIAL_CHAIN 0
2626 if ((i = OCSP_basic_verify(bs, SSL_get_peer_cert_chain(ssl),
2629 tls_out.dane_verified
2630 ? have_verified_OCSP_signer
2631 ? OCSP_NOVERIFY | OCSP_NOEXPLICIT
2632 : OCSP_PARTIAL_CHAIN | OCSP_NOEXPLICIT
2635 OCSP_NOEXPLICIT)) <= 0)
2637 DEBUG(D_tls) debug_printf("OCSP_basic_verify() fail: returned %d\n", i);
2638 if (ERR_peek_error())
2640 tls_out.ocsp = OCSP_FAILED;
2641 if (LOGGING(tls_cipher))
2643 static uschar peerdn[256];
2644 const uschar * errstr;;
2646 #if OPENSSL_VERSION_NUMBER >= 0x30000000L
2647 ERR_peek_error_all(NULL, NULL, NULL, CCSS &errstr, NULL);
2650 errstr = CUS ERR_reason_error_string(ERR_peek_error());
2652 X509_NAME_oneline(X509_get_subject_name(SSL_get_peer_certificate(ssl)),
2653 CS peerdn, sizeof(peerdn));
2654 log_write(0, LOG_MAIN,
2655 "[%s] %s Received TLS cert (DN: '%.*s') status response, "
2656 "itself unverifiable: %s",
2657 deliver_host_address, deliver_host,
2658 (int)sizeof(peerdn), peerdn, errstr);
2662 BIO_printf(bp, "OCSP response verify failure\n");
2663 ERR_print_errors(bp);
2666 int len = (int) BIO_get_mem_data(bp, CSS &s);
2667 if (len > 0) debug_printf("%.*s", len, s);
2670 OCSP_RESPONSE_print(bp, rsp, 0);
2675 DEBUG(D_tls) debug_printf("no explicit trust for OCSP signing"
2676 " in the root CA certificate; ignoring\n");
2679 DEBUG(D_tls) debug_printf("OCSP response well-formed and signed OK\n");
2681 /*XXX So we have a good stapled OCSP status. How do we know
2682 it is for the cert of interest? OpenSSL 1.1.0 has a routine
2683 OCSP_resp_find_status() which matches on a cert id, which presumably
2684 we should use. Making an id needs OCSP_cert_id_new(), which takes
2685 issuerName, issuerKey, serialNumber. Are they all in the cert?
2687 For now, carry on blindly accepting the resp. */
2690 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
2691 OCSP_resp_count(bs) - 1;
2693 sk_OCSP_SINGLERESP_num(sresp) - 1;
2697 OCSP_SINGLERESP * single = OCSP_resp_get0(bs, idx);
2699 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
2701 /*XXX so I can see putting a loop in here to handle a rsp with >1 singleresp
2702 - but what happens with a GnuTLS-style input?
2704 we could do with a debug label for each singleresp
2705 - it has a certID with a serialNumber, but I see no API to get that
2707 status = OCSP_single_get0_status(single, &reason, &rev,
2708 &thisupd, &nextupd);
2712 time_print(bp, "This OCSP Update", thisupd);
2713 if (nextupd) time_print(bp, "Next OCSP Update", nextupd);
2715 if (!OCSP_check_validity(thisupd, nextupd,
2716 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
2718 tls_out.ocsp = OCSP_FAILED;
2719 DEBUG(D_tls) ERR_print_errors(bp);
2720 cbinfo->u_ocsp.client.verify_errstr =
2721 US"(SSL_connect) Server certificate status is out-of-date";
2722 log_write(0, LOG_MAIN, "OCSP dates invalid");
2726 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
2727 OCSP_cert_status_str(status));
2730 case V_OCSP_CERTSTATUS_GOOD:
2731 continue; /* the idx loop */
2732 case V_OCSP_CERTSTATUS_REVOKED:
2733 cbinfo->u_ocsp.client.verify_errstr =
2734 US"(SSL_connect) Server certificate revoked";
2735 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
2736 reason != -1 ? "; reason: " : "",
2737 reason != -1 ? OCSP_crl_reason_str(reason) : "");
2738 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
2741 cbinfo->u_ocsp.client.verify_errstr =
2742 US"(SSL_connect) Server certificate has unknown status";
2743 log_write(0, LOG_MAIN,
2744 "Server certificate status unknown, in OCSP stapling");
2752 tls_out.ocsp = OCSP_VFIED;
2756 tls_out.ocsp = OCSP_FAILED;
2757 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2761 int len = (int) BIO_get_mem_data(bp, CSS &s);
2762 if (len > 0) debug_printf("%.*s", len, s);
2767 OCSP_RESPONSE_free(rsp);
2770 #endif /*!DISABLE_OCSP*/
2773 /*************************************************
2774 * Initialize for TLS *
2775 *************************************************/
2776 /* Called from both server and client code, to do preliminary initialization
2777 of the library. We allocate and return a context structure.
2780 host connected host, if client; NULL if server
2781 ob transport options block, if client; NULL if server
2782 ocsp_file file of stapling info (server); flag for require ocsp (client)
2783 addr address if client; NULL if server (for some randomness)
2784 caller_state place to put pointer to allocated state-struct
2785 errstr error string pointer
2787 Returns: OK/DEFER/FAIL
2791 tls_init(host_item * host, smtp_transport_options_block * ob,
2792 #ifndef DISABLE_OCSP
2795 address_item *addr, exim_openssl_state_st ** caller_state,
2796 tls_support * tlsp, uschar ** errstr)
2799 exim_openssl_state_st * state;
2802 if (host) /* client */
2804 state = store_malloc(sizeof(exim_openssl_state_st));
2805 memset(state, 0, sizeof(*state));
2806 state->certificate = ob->tls_certificate;
2807 state->privatekey = ob->tls_privatekey;
2808 state->is_server = FALSE;
2809 state->dhparam = NULL;
2810 state->lib_state = ob->tls_preload;
2814 state = &state_server;
2815 state->certificate = tls_certificate;
2816 state->privatekey = tls_privatekey;
2817 state->is_server = TRUE;
2818 state->dhparam = tls_dhparam;
2819 state->lib_state = state_server.lib_state;
2825 if (!state->lib_state.pri_string)
2826 state->server_cipher_list = NULL;
2828 #ifndef DISABLE_EVENT
2829 state->event_action = NULL;
2834 /* It turns out that we need to seed the random number generator this early in
2835 order to get the full complement of ciphers to work. It took me roughly a day
2836 of work to discover this by experiment.
2838 On systems that have /dev/urandom, SSL may automatically seed itself from
2839 there. Otherwise, we have to make something up as best we can. Double check
2842 Although we likely called this before, at daemon startup, this is a chance
2843 to mix in further variable info (time, pid) if needed. */
2845 if (!lib_rand_init(addr))
2846 return tls_error(US"RAND_status", host,
2847 US"unable to seed random number generator", errstr);
2849 /* Apply administrator-supplied work-arounds.
2850 Historically we applied just one requested option,
2851 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
2852 moved to an administrator-controlled list of options to specify and
2853 grandfathered in the first one as the default value for "openssl_options".
2855 No OpenSSL version number checks: the options we accept depend upon the
2856 availability of the option value macros from OpenSSL. */
2859 if (!tls_openssl_options_parse(openssl_options, &init_options))
2860 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
2862 /* Create a context.
2863 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
2864 negotiation in the different methods; as far as I can tell, the only
2865 *_{server,client}_method which allows negotiation is SSLv23, which exists even
2866 when OpenSSL is built without SSLv2 support.
2867 By disabling with openssl_options, we can let admins re-enable with the
2870 if (!(ctx = state->lib_state.lib_ctx))
2872 if ((rc = lib_ctx_new(&ctx, host, errstr)) != OK)
2874 state->lib_state.lib_ctx = ctx;
2877 #ifndef DISABLE_TLS_RESUME
2878 tlsp->resumption = RESUME_SUPPORTED;
2882 #ifndef DISABLE_TLS_RESUME
2883 /* Should the server offer session resumption? */
2884 if (!host && verify_check_host(&tls_resumption_hosts) == OK)
2886 DEBUG(D_tls) debug_printf("tls_resumption_hosts overrides openssl_options\n");
2887 init_options &= ~SSL_OP_NO_TICKET;
2888 tlsp->resumption |= RESUME_SERVER_TICKET; /* server will give ticket on request */
2889 tlsp->host_resumable = TRUE;
2893 #ifdef OPENSSL_MIN_PROTO_VERSION
2894 SSL_CTX_set_min_proto_version(ctx, SSL3_VERSION);
2896 DEBUG(D_tls) debug_printf("setting SSL CTX options: %016lx\n", init_options);
2897 SSL_CTX_set_options(ctx, init_options);
2899 uint64_t readback = SSL_CTX_clear_options(ctx, ~init_options);
2900 if (readback != init_options)
2901 return tls_error(string_sprintf(
2902 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
2906 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
2908 /* We'd like to disable session cache unconditionally, but foolish Outlook
2909 Express clients then give up the first TLS connection and make a second one
2910 (which works). Only when there is an IMAP service on the same machine.
2911 Presumably OE is trying to use the cache for A on B. Leave it enabled for
2912 now, until we work out a decent way of presenting control to the config. It
2913 will never be used because we use a new context every time. */
2915 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
2918 /* Initialize with DH parameters if supplied */
2919 /* Initialize ECDH temp key parameter selection */
2923 if (state->lib_state.dh)
2924 { DEBUG(D_tls) debug_printf("TLS: DH params were preloaded\n"); }
2926 if (!init_dh(ctx, state->dhparam, errstr)) return DEFER;
2928 if (state->lib_state.ecdh)
2929 { DEBUG(D_tls) debug_printf("TLS: ECDH curve was preloaded\n"); }
2931 if (!init_ecdh(ctx, errstr)) return DEFER;
2934 /* Set up certificate and key (and perhaps OCSP info) */
2936 if (state->lib_state.conn_certs)
2939 debug_printf("TLS: %s certs were preloaded\n", host ? "client":"server");
2943 #ifndef DISABLE_OCSP
2944 if (!host) /* server */
2946 state->u_ocsp.server.file = ocsp_file;
2947 state->u_ocsp.server.file_expanded = NULL;
2948 state->u_ocsp.server.olist = NULL;
2951 if ((rc = tls_expand_session_files(ctx, state, errstr)) != OK) return rc;
2954 /* If we need to handle SNI or OCSP, do so */
2956 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2957 # ifndef DISABLE_OCSP
2958 if (!host && !(state->u_ocsp.server.verify_stack = sk_X509_new_null()))
2960 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
2965 if (!host) /* server */
2967 # ifndef DISABLE_OCSP
2968 /* We check u_ocsp.server.file, not server.olist, because we care about if
2969 the option exists, not what the current expansion might be, as SNI might
2970 change the certificate and OCSP file in use between now and the time the
2971 callback is invoked. */
2972 if (state->u_ocsp.server.file)
2974 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
2975 SSL_CTX_set_tlsext_status_arg(ctx, state);
2978 /* We always do this, so that $tls_sni is available even if not used in
2980 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
2981 SSL_CTX_set_tlsext_servername_arg(ctx, state);
2983 # ifdef EXIM_HAVE_ALPN
2984 if (tls_alpn && *tls_alpn)
2987 if ( expand_check(tls_alpn, US"tls_alpn", &exp_alpn, errstr)
2988 && *exp_alpn && !isblank(*exp_alpn))
2990 tls_alpn = exp_alpn; /* subprocess so ok to overwrite */
2991 SSL_CTX_set_alpn_select_cb(ctx, tls_server_alpn_cb, state);
2998 # ifndef DISABLE_OCSP
3000 if(ocsp_file) /* wanting stapling */
3002 if (!(state->u_ocsp.client.verify_store = X509_STORE_new()))
3004 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
3008 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
3009 SSL_CTX_set_tlsext_status_arg(ctx, state);
3012 #endif /*EXIM_HAVE_OPENSSL_TLSEXT*/
3014 state->verify_cert_hostnames = NULL;
3016 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
3017 /* Set up the RSA callback */
3018 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
3021 /* Finally, set the session cache timeout, and we are done.
3022 The period appears to be also used for (server-generated) session tickets */
3024 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
3025 DEBUG(D_tls) debug_printf("Initialized TLS\n");
3027 *caller_state = state;
3035 /*************************************************
3036 * Get name of cipher in use *
3037 *************************************************/
3040 Argument: pointer to an SSL structure for the connection
3041 pointer to number of bits for cipher
3042 Returns: pointer to allocated string in perm-pool
3046 construct_cipher_name(SSL * ssl, const uschar * ver, int * bits)
3048 int pool = store_pool;
3049 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
3050 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
3051 the accessor functions use const in the prototype. */
3053 const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
3056 SSL_CIPHER_get_bits(c, bits);
3058 store_pool = POOL_PERM;
3059 s = string_sprintf("%s:%s:%u", ver, SSL_CIPHER_get_name(c), *bits);
3061 DEBUG(D_tls) debug_printf("Cipher: %s\n", s);
3066 /* Get IETF-standard name for ciphersuite.
3067 Argument: pointer to an SSL structure for the connection
3068 Returns: pointer to string
3071 static const uschar *
3072 cipher_stdname_ssl(SSL * ssl)
3074 #ifdef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
3075 return CUS SSL_CIPHER_standard_name(SSL_get_current_cipher(ssl));
3077 ushort id = 0xffff & SSL_CIPHER_get_id(SSL_get_current_cipher(ssl));
3078 return cipher_stdname(id >> 8, id & 0xff);
3083 static const uschar *
3084 tlsver_name(SSL * ssl)
3087 int pool = store_pool;
3089 store_pool = POOL_PERM;
3090 s = string_copy(US SSL_get_version(ssl));
3092 if ((p = Ustrchr(s, 'v'))) /* TLSv1.2 -> TLS1.2 */
3093 for (;; p++) if (!(*p = p[1])) break;
3099 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned siz)
3101 /*XXX we might consider a list-of-certs variable for the cert chain.
3102 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
3103 in list-handling functions, also consider the difference between the entire
3104 chain and the elements sent by the peer. */
3106 tlsp->peerdn = NULL;
3108 /* Will have already noted peercert on a verify fail; possibly not the leaf */
3109 if (!tlsp->peercert)
3110 tlsp->peercert = SSL_get_peer_certificate(ssl);
3111 /* Beware anonymous ciphers which lead to server_cert being NULL */
3113 if (!X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, siz))
3114 { DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n"); }
3117 int oldpool = store_pool;
3119 peerdn[siz-1] = '\0'; /* paranoia */
3120 store_pool = POOL_PERM;
3121 tlsp->peerdn = string_copy(peerdn);
3122 store_pool = oldpool;
3124 /* We used to set CV in the cert-verify callbacks (either plain or dane)
3125 but they don't get called on session-resumption. So use the official
3126 interface, which uses the resumed value. Unfortunately this claims verified
3127 when it actually failed but we're in try-verify mode, due to us wanting the
3128 knowlege that it failed so needing to have the callback and forcing a
3129 permissive return. If we don't force it, the TLS startup is failed.
3130 The extra bit of information is set in verify_override in the cb, stashed
3131 for resumption next to the TLS session, and used here. */
3133 if (!tlsp->verify_override)
3134 tlsp->certificate_verified =
3136 tlsp->dane_verified ||
3138 SSL_get_verify_result(ssl) == X509_V_OK;
3146 /*************************************************
3147 * Set up for verifying certificates *
3148 *************************************************/
3150 #ifndef DISABLE_OCSP
3151 /* In the server, load certs from file, return TRUE on success */
3154 chain_from_pem_file(const uschar * file, STACK_OF(X509) ** vp)
3157 STACK_OF(X509) * verify_stack = *vp;
3160 while (sk_X509_num(verify_stack) > 0)
3161 X509_free(sk_X509_pop(verify_stack));
3163 verify_stack = sk_X509_new_null();
3165 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
3166 for (X509 * x; x = PEM_read_bio_X509(bp, NULL, 0, NULL); )
3167 sk_X509_push(verify_stack, x);
3176 /* Called by both client and server startup; on the server possibly
3177 repeated after a Server Name Indication.
3180 sctx SSL_CTX* to initialise
3181 certsp certs file, returned expanded
3182 crl CRL file or NULL
3183 host NULL in a server; the remote host in a client
3184 errstr error string pointer
3186 Returns: OK/DEFER/FAIL
3190 setup_certs(SSL_CTX * sctx, uschar ** certsp, uschar * crl, host_item * host,
3193 uschar * expcerts, * expcrl;
3195 if (!expand_check(*certsp, US"tls_verify_certificates", &expcerts, errstr))
3197 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3200 if (expcerts && *expcerts)
3202 /* Tell the library to use its compiled-in location for the system default
3203 CA bundle. Then add the ones specified in the config, if any. */
3205 if (!SSL_CTX_set_default_verify_paths(sctx))
3206 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
3208 if (Ustrcmp(expcerts, "system") != 0 && Ustrncmp(expcerts, "system,", 7) != 0)
3210 struct stat statbuf;
3212 if (Ustat(expcerts, &statbuf) < 0)
3214 log_write(0, LOG_MAIN|LOG_PANIC,
3215 "failed to stat %s for certificates", expcerts);
3221 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
3222 { file = NULL; dir = expcerts; }
3225 STACK_OF(X509) * verify_stack =
3226 #ifndef DISABLE_OCSP
3227 !host ? state_server.u_ocsp.server.verify_stack :
3230 STACK_OF(X509) ** vp = &verify_stack;
3232 file = expcerts; dir = NULL;
3233 #ifndef DISABLE_OCSP
3234 /* In the server if we will be offering an OCSP proof; load chain from
3235 file for verifying the OCSP proof at load time. */
3237 /*XXX Glitch! The file here is tls_verify_certs: the chain for verifying the client cert.
3238 This is inconsistent with the need to verify the OCSP proof of the server cert.
3240 /* *debug_printf("file for checking server ocsp stapling is: %s\n", file); */
3242 && statbuf.st_size > 0
3243 && state_server.u_ocsp.server.file
3244 && !chain_from_pem_file(file, vp)
3247 log_write(0, LOG_MAIN|LOG_PANIC,
3248 "failed to load cert chain from %s", file);
3254 /* If a certificate file is empty, the load function fails with an
3255 unhelpful error message. If we skip it, we get the correct behaviour (no
3256 certificates are recognized, but the error message is still misleading (it
3257 says no certificate was supplied). But this is better. */
3259 if ( (!file || statbuf.st_size > 0)
3260 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
3261 return tls_error(US"SSL_CTX_load_verify_locations",
3262 host, NULL, errstr);
3264 /* On the server load the list of CAs for which we will accept certs, for
3265 sending to the client. This is only for the one-file
3266 tls_verify_certificates variant.
3267 If a list isn't loaded into the server, but some verify locations are set,
3268 the server end appears to make a wildcard request for client certs.
3269 Meanwhile, the client library as default behaviour *ignores* the list
3270 we send over the wire - see man SSL_CTX_set_client_cert_cb.
3271 Because of this, and that the dir variant is likely only used for
3272 the public-CA bundle (not for a private CA), not worth fixing. */
3276 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
3277 int i = sk_X509_NAME_num(names);
3279 if (!host) SSL_CTX_set_client_CA_list(sctx, names);
3280 DEBUG(D_tls) debug_printf("Added %d additional certificate authorit%s\n",
3281 i, i>1 ? "ies":"y");
3285 debug_printf("Added dir for additional certificate authorities\n");
3289 /* Handle a certificate revocation list. */
3291 #if OPENSSL_VERSION_NUMBER > 0x00907000L
3293 /* This bit of code is now the version supplied by Lars Mainka. (I have
3294 merely reformatted it into the Exim code style.)
3296 "From here I changed the code to add support for multiple crl's
3297 in pem format in one file or to support hashed directory entries in
3298 pem format instead of a file. This method now uses the library function
3299 X509_STORE_load_locations to add the CRL location to the SSL context.
3300 OpenSSL will then handle the verify against CA certs and CRLs by
3301 itself in the verify callback." */
3303 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
3304 if (expcrl && *expcrl)
3306 struct stat statbufcrl;
3307 if (Ustat(expcrl, &statbufcrl) < 0)
3309 log_write(0, LOG_MAIN|LOG_PANIC,
3310 "failed to stat %s for certificates revocation lists", expcrl);
3315 /* is it a file or directory? */
3317 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
3318 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
3322 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
3328 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
3330 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
3331 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
3333 /* setting the flags to check against the complete crl chain */
3335 X509_STORE_set_flags(cvstore,
3336 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
3340 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
3349 tls_dump_keylog(SSL * ssl)
3351 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3352 BIO * bp = BIO_new(BIO_s_mem());
3355 SSL_SESSION_print_keylog(bp, SSL_get_session(ssl));
3356 len = (int) BIO_get_mem_data(bp, CSS &s);
3357 if (len > 0) debug_printf("%.*s", len, s);
3363 /* Channel-binding info for authenticators
3364 See description in https://paquier.xyz/postgresql-2/channel-binding-openssl/
3369 tls_get_channel_binding(SSL * ssl, tls_support * tlsp, const void * taintval)
3374 #ifdef EXIM_HAVE_EXPORT_CHNL_BNGNG
3375 if (SSL_version(ssl) > TLS1_2_VERSION)
3377 /* It's not documented by OpenSSL how big the output buffer must be.
3378 The OpenSSL testcases use 80 bytes but don't say why. The GnuTLS impl only
3379 serves out 32B. RFC 9266 says it is 32B.
3380 Interop fails unless we use the same each end. */
3383 tlsp->channelbind_exporter = TRUE;
3384 taintval = GET_UNTAINTED;
3385 if (SSL_export_keying_material(ssl,
3386 s = store_get((int)len, taintval), len,
3387 "EXPORTER-Channel-Binding", (size_t) 24,
3394 len = SSL_get_peer_finished(ssl, &c, 0);
3395 len = SSL_get_peer_finished(ssl, s = store_get((int)len, taintval), len);
3400 int old_pool = store_pool;
3401 store_pool = POOL_PERM;
3402 tlsp->channelbinding = b64encode_taint(CUS s, (int)len, taintval);
3403 store_pool = old_pool;
3404 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage %p %p\n", tlsp->channelbinding, tlsp);
3409 /*************************************************
3410 * Start a TLS session in a server *
3411 *************************************************/
3412 /* This is called when Exim is running as a server, after having received
3413 the STARTTLS command. It must respond to that command, and then negotiate
3417 errstr pointer to error message
3419 Returns: OK on success
3420 DEFER for errors before the start of the negotiation
3421 FAIL for errors during the negotiation; the server can't
3426 tls_server_start(uschar ** errstr)
3429 uschar * expciphers;
3430 exim_openssl_state_st * dummy_statep;
3433 static uschar peerdn[256];
3435 /* Check for previous activation */
3437 if (tls_in.active.sock >= 0)
3439 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
3440 smtp_printf("554 Already in TLS\r\n", FALSE);
3444 /* Initialize the SSL library. If it fails, it will already have logged
3447 rc = tls_init(NULL, NULL,
3448 #ifndef DISABLE_OCSP
3451 NULL, &dummy_statep, &tls_in, errstr);
3452 if (rc != OK) return rc;
3453 ctx = state_server.lib_state.lib_ctx;
3455 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
3456 were historically separated by underscores. So that I can use either form in my
3457 tests, and also for general convenience, we turn underscores into hyphens here.
3459 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
3460 for TLS 1.3 . Since we do not call it at present we get the default list:
3461 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
3464 if (state_server.lib_state.pri_string)
3465 { DEBUG(D_tls) debug_printf("TLS: cipher list was preloaded\n"); }
3468 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
3473 normalise_ciphers(&expciphers, tls_require_ciphers);
3474 if ((rc = server_load_ciphers(ctx, &state_server, expciphers, errstr)) != OK)
3479 /* If this is a host for which certificate verification is mandatory or
3480 optional, set up appropriately. */
3482 tls_in.certificate_verified = FALSE;
3484 tls_in.dane_verified = FALSE;
3486 server_verify_callback_called = FALSE;
3488 if (verify_check_host(&tls_verify_hosts) == OK)
3489 server_verify_optional = FALSE;
3490 else if (verify_check_host(&tls_try_verify_hosts) == OK)
3491 server_verify_optional = TRUE;
3496 uschar * v_certs = tls_verify_certificates;
3498 if (state_server.lib_state.cabundle)
3500 DEBUG(D_tls) debug_printf("TLS: CA bundle for server was preloaded\n");
3501 setup_cert_verify(ctx, server_verify_optional, verify_callback_server);
3505 if ((rc = setup_certs(ctx, &v_certs, tls_crl, NULL, errstr)) != OK)
3507 if (v_certs && *v_certs)
3508 setup_cert_verify(ctx, server_verify_optional, verify_callback_server);
3513 #ifndef DISABLE_TLS_RESUME
3514 # if OPENSSL_VERSION_NUMBER < 0x30000000L
3515 SSL_CTX_set_tlsext_ticket_key_cb(ctx, ticket_key_callback);
3516 /* despite working, appears to always return failure, so ignoring */
3518 SSL_CTX_set_tlsext_ticket_key_evp_cb(ctx, ticket_key_callback);
3519 /* despite working, appears to always return failure, so ignoring */
3523 #ifdef OPENSSL_HAVE_NUM_TICKETS
3524 # ifndef DISABLE_TLS_RESUME
3525 SSL_CTX_set_num_tickets(ctx, tls_in.host_resumable ? 1 : 0);
3527 SSL_CTX_set_num_tickets(ctx, 0); /* send no TLS1.3 stateful-tickets */
3532 /* Prepare for new connection */
3534 if (!(ssl = SSL_new(ctx)))
3535 return tls_error(US"SSL_new", NULL, NULL, errstr);
3536 state_server.lib_state.lib_ssl = ssl;
3538 /* Warning: we used to SSL_clear(ssl) here, it was removed.
3540 * With the SSL_clear(), we get strange interoperability bugs with
3541 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
3542 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
3544 * The SSL_clear() call is to let an existing SSL* be reused, typically after
3545 * session shutdown. In this case, we have a brand new object and there's no
3546 * obvious reason to immediately clear it. I'm guessing that this was
3547 * originally added because of incomplete initialisation which the clear fixed,
3548 * in some historic release.
3551 /* Set context and tell client to go ahead, except in the case of TLS startup
3552 on connection, where outputting anything now upsets the clients and tends to
3553 make them disconnect. We need to have an explicit fflush() here, to force out
3554 the response. Other smtp_printf() calls do not need it, because in non-TLS
3555 mode, the fflush() happens when smtp_getc() is called. */
3557 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
3558 if (!tls_in.on_connect)
3560 smtp_printf("220 TLS go ahead\r\n", FALSE);
3564 /* Now negotiate the TLS session. We put our own timer on it, since it seems
3565 that the OpenSSL library doesn't. */
3567 SSL_set_wfd(ssl, fileno(smtp_out));
3568 SSL_set_rfd(ssl, fileno(smtp_in));
3569 SSL_set_accept_state(ssl);
3571 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
3574 sigalrm_seen = FALSE;
3575 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3576 rc = SSL_accept(ssl);
3581 int error = SSL_get_error(ssl, rc);
3584 case SSL_ERROR_NONE:
3587 case SSL_ERROR_ZERO_RETURN:
3588 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3589 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
3590 #ifndef DISABLE_EVENT
3591 (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);
3593 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
3596 tls_close(NULL, TLS_NO_SHUTDOWN);
3599 /* Handle genuine errors */
3603 int r = ERR_GET_REASON(ERR_peek_error());
3604 if ( r == SSL_R_WRONG_VERSION_NUMBER
3605 #ifdef SSL_R_VERSION_TOO_LOW
3606 || r == SSL_R_VERSION_TOO_LOW
3608 || r == SSL_R_UNKNOWN_PROTOCOL || r == SSL_R_UNSUPPORTED_PROTOCOL)
3609 s = string_sprintf("(%s)", SSL_get_version(ssl));
3610 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : s, errstr);
3611 #ifndef DISABLE_EVENT
3612 (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);
3618 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
3619 if (error == SSL_ERROR_SYSCALL)
3623 *errstr = US"SSL_accept: TCP connection closed by peer";
3624 #ifndef DISABLE_EVENT
3625 (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);
3629 DEBUG(D_tls) debug_printf(" - syscall %s\n", strerror(errno));
3631 (void) tls_error(US"SSL_accept", NULL,
3632 sigalrm_seen ? US"timed out"
3633 : ERR_peek_error() ? NULL : string_sprintf("ret %d", error),
3635 #ifndef DISABLE_EVENT
3636 (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);
3642 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
3643 ERR_clear_error(); /* Even success can leave errors in the stack. Seen with
3644 anon-authentication ciphersuite negotiated. */
3646 #ifndef DISABLE_TLS_RESUME
3647 if (SSL_session_reused(ssl))
3649 tls_in.resumption |= RESUME_USED;
3650 DEBUG(D_tls) debug_printf("Session reused\n");
3654 #ifdef EXIM_HAVE_ALPN
3655 /* If require-alpn, check server_seen_alpn here. Else abort TLS */
3656 if (!tls_alpn || !*tls_alpn)
3657 { DEBUG(D_tls) debug_printf("TLS: was not watching for ALPN\n"); }
3658 else if (!server_seen_alpn)
3659 if (verify_check_host(&hosts_require_alpn) == OK)
3661 /* We'd like to send a definitive Alert but OpenSSL provides no facility */
3663 tls_error(US"handshake", NULL, US"ALPN required but not negotiated", errstr);
3667 { DEBUG(D_tls) debug_printf("TLS: no ALPN presented in handshake\n"); }
3670 const uschar * name;
3672 SSL_get0_alpn_selected(ssl, &name, &len);
3674 debug_printf("ALPN negotiated: '%.*s'\n", (int)*name, name+1);
3676 debug_printf("ALPN: no protocol negotiated\n");
3681 /* TLS has been set up. Record data for the connection,
3682 adjust the input functions to read via TLS, and initialize things. */
3684 #ifdef SSL_get_extms_support
3685 /*XXX what does this return for tls1.3 ? */
3686 tls_in.ext_master_secret = SSL_get_extms_support(ssl) == 1;
3688 peer_cert(ssl, &tls_in, peerdn, sizeof(peerdn));
3690 tls_in.ver = tlsver_name(ssl);
3691 tls_in.cipher = construct_cipher_name(ssl, tls_in.ver, &tls_in.bits);
3692 tls_in.cipher_stdname = cipher_stdname_ssl(ssl);
3697 if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)))
3698 debug_printf("Shared ciphers: %s\n", buf);
3700 tls_dump_keylog(ssl);
3702 #ifdef EXIM_HAVE_SESSION_TICKET
3704 SSL_SESSION * ss = SSL_get_session(ssl);
3705 if (SSL_SESSION_has_ticket(ss)) /* 1.1.0 */
3706 debug_printf("The session has a ticket, life %lu seconds\n",
3707 SSL_SESSION_get_ticket_lifetime_hint(ss));
3712 /* Record the certificate we presented */
3714 X509 * crt = SSL_get_certificate(ssl);
3715 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
3718 tls_get_channel_binding(ssl, &tls_in, GET_UNTAINTED);
3720 /* Only used by the server-side tls (tls_in), including tls_getc.
3721 Client-side (tls_out) reads (seem to?) go via
3722 smtp_read_response()/ip_recv().
3723 Hence no need to duplicate for _in and _out.
3725 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
3726 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
3727 ssl_xfer_eof = ssl_xfer_error = FALSE;
3729 receive_getc = tls_getc;
3730 receive_getbuf = tls_getbuf;
3731 receive_get_cache = tls_get_cache;
3732 receive_hasc = tls_hasc;
3733 receive_ungetc = tls_ungetc;
3734 receive_feof = tls_feof;
3735 receive_ferror = tls_ferror;
3737 tls_in.active.sock = fileno(smtp_out);
3738 tls_in.active.tls_ctx = NULL; /* not using explicit ctx for server-side */
3746 tls_client_basic_ctx_init(SSL_CTX * ctx,
3747 host_item * host, smtp_transport_options_block * ob, exim_openssl_state_st * state,
3752 /* Back-compatible old behaviour if tls_verify_certificates is set but both
3753 tls_verify_hosts and tls_try_verify_hosts are not set. Check only the specified
3754 host patterns if one of them is set with content. */
3756 if ( ( ( !ob->tls_verify_hosts || !ob->tls_verify_hosts
3757 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3759 && ( !ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts
3760 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3763 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
3765 client_verify_optional = FALSE;
3766 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
3767 client_verify_optional = TRUE;
3772 uschar * v_certs = ob->tls_verify_certificates;
3774 if (state->lib_state.cabundle)
3776 DEBUG(D_tls) debug_printf("TLS: CA bundle for tpt was preloaded\n");
3777 setup_cert_verify(ctx, client_verify_optional, verify_callback_client);
3781 if ((rc = setup_certs(ctx, &v_certs, ob->tls_crl, host, errstr)) != OK)
3783 if (v_certs && *v_certs)
3784 setup_cert_verify(ctx, client_verify_optional, verify_callback_client);
3788 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
3790 state->verify_cert_hostnames =
3792 string_domain_utf8_to_alabel(host->certname, NULL);
3796 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
3797 state->verify_cert_hostnames);
3805 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
3808 const char * hostnames[2] = { CS host->name, NULL };
3811 if (DANESSL_init(ssl, NULL, hostnames) != 1)
3812 return tls_error(US"hostnames load", host, NULL, errstr);
3814 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
3815 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
3816 ) if (rr->type == T_TLSA && rr->size > 3)
3818 const uschar * p = rr->data;
3819 uint8_t usage, selector, mtype;
3820 const char * mdname;
3824 /* Only DANE-TA(2) and DANE-EE(3) are supported */
3825 if (usage != 2 && usage != 3) continue;
3832 default: continue; /* Only match-types 0, 1, 2 are supported */
3833 case 0: mdname = NULL; break;
3834 case 1: mdname = "sha256"; break;
3835 case 2: mdname = "sha512"; break;
3839 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
3842 return tls_error(US"tlsa load", host, NULL, errstr);
3843 case 0: /* action not taken */
3847 tls_out.tlsa_usage |= 1<<usage;
3853 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
3856 #endif /*SUPPORT_DANE*/
3860 #ifndef DISABLE_TLS_RESUME
3861 /* On the client, get any stashed session for the given IP from hints db
3862 and apply it to the ssl-connection for attempted resumption. */
3865 tls_retrieve_session(tls_support * tlsp, SSL * ssl)
3867 if (tlsp->host_resumable)
3869 dbdata_tls_session * dt;
3871 open_db dbblock, * dbm_file;
3873 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
3875 debug_printf("checking for resumable session for %s\n", tlsp->resume_index);
3876 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3878 if ((dt = dbfn_read_with_length(dbm_file, tlsp->resume_index, &len)))
3880 SSL_SESSION * ss = NULL;
3881 const uschar * sess_asn1 = dt->session;
3883 len -= sizeof(dbdata_tls_session);
3884 if (!(d2i_SSL_SESSION(&ss, &sess_asn1, (long)len)))
3888 ERR_error_string_n(ERR_get_error(),
3889 ssl_errstring, sizeof(ssl_errstring));
3890 debug_printf("decoding session: %s\n", ssl_errstring);
3895 unsigned long lifetime =
3896 #ifdef EXIM_HAVE_SESSION_TICKET
3897 SSL_SESSION_get_ticket_lifetime_hint(ss);
3898 #else /* Use, fairly arbitrilarily, what we as server would */
3899 f.running_in_test_harness ? 6 : ssl_session_timeout;
3901 if (lifetime + dt->time_stamp < time(NULL))
3903 DEBUG(D_tls) debug_printf("session expired\n");
3904 dbfn_delete(dbm_file, tlsp->resume_index);
3906 else if (SSL_set_session(ssl, ss))
3908 DEBUG(D_tls) debug_printf("good session\n");
3909 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
3910 tlsp->verify_override = dt->verify_override;
3911 tlsp->ocsp = dt->ocsp;
3915 ERR_error_string_n(ERR_get_error(),
3916 ssl_errstring, sizeof(ssl_errstring));
3917 debug_printf("applying session to ssl: %s\n", ssl_errstring);
3922 DEBUG(D_tls) debug_printf("no session record\n");
3923 dbfn_close(dbm_file);
3929 /* On the client, save the session for later resumption */
3932 tls_save_session_cb(SSL * ssl, SSL_SESSION * ss)
3934 exim_openssl_state_st * cbinfo = SSL_get_ex_data(ssl, tls_exdata_idx);
3937 DEBUG(D_tls) debug_printf("tls_save_session_cb\n");
3939 if (!cbinfo || !(tlsp = cbinfo->tlsp)->host_resumable) return 0;
3941 # ifdef OPENSSL_HAVE_NUM_TICKETS
3942 if (SSL_SESSION_is_resumable(ss)) /* 1.1.1 */
3945 int len = i2d_SSL_SESSION(ss, NULL);
3946 int dlen = sizeof(dbdata_tls_session) + len;
3947 dbdata_tls_session * dt = store_get(dlen, GET_TAINTED);
3948 uschar * s = dt->session;
3949 open_db dbblock, * dbm_file;
3951 DEBUG(D_tls) debug_printf("session is resumable\n");
3952 tlsp->resumption |= RESUME_SERVER_TICKET; /* server gave us a ticket */
3954 dt->verify_override = tlsp->verify_override;
3955 dt->ocsp = tlsp->ocsp;
3956 (void) i2d_SSL_SESSION(ss, &s); /* s gets bumped to end */
3958 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3960 dbfn_write(dbm_file, tlsp->resume_index, dt, dlen);
3961 dbfn_close(dbm_file);
3962 DEBUG(D_tls) debug_printf("wrote session (len %u) to db\n",
3970 /* Construct a key for session DB lookup, and setup the SSL_CTX for resumption */
3973 tls_client_ctx_resume_prehandshake(
3974 exim_openssl_client_tls_ctx * exim_client_ctx, smtp_connect_args * conn_args,
3975 tls_support * tlsp, smtp_transport_options_block * ob)
3977 tlsp->host_resumable = TRUE;
3978 tls_client_resmption_key(tlsp, conn_args, ob);
3980 SSL_CTX_set_session_cache_mode(exim_client_ctx->ctx,
3981 SSL_SESS_CACHE_CLIENT
3982 | SSL_SESS_CACHE_NO_INTERNAL | SSL_SESS_CACHE_NO_AUTO_CLEAR);
3983 SSL_CTX_sess_set_new_cb(exim_client_ctx->ctx, tls_save_session_cb);
3987 tls_client_ssl_resume_prehandshake(SSL * ssl, tls_support * tlsp,
3988 host_item * host, uschar ** errstr)
3990 if (tlsp->host_resumable)
3993 debug_printf("tls_resumption_hosts overrides openssl_options, enabling tickets\n");
3994 SSL_clear_options(ssl, SSL_OP_NO_TICKET);
3996 tls_exdata_idx = SSL_get_ex_new_index(0, 0, 0, 0, 0);
3997 if (!SSL_set_ex_data(ssl, tls_exdata_idx, client_static_state))
3999 tls_error(US"set ex_data", host, NULL, errstr);
4002 debug_printf("tls_exdata_idx %d cbinfo %p\n", tls_exdata_idx, client_static_state);
4005 tlsp->resumption = RESUME_SUPPORTED;
4006 /* Pick up a previous session, saved on an old ticket */
4007 tls_retrieve_session(tlsp, ssl);
4012 tls_client_resume_posthandshake(exim_openssl_client_tls_ctx * exim_client_ctx,
4015 if (SSL_session_reused(exim_client_ctx->ssl))
4017 DEBUG(D_tls) debug_printf("The session was reused\n");
4018 tlsp->resumption |= RESUME_USED;
4021 #endif /* !DISABLE_TLS_RESUME */
4024 #ifdef EXIM_HAVE_ALPN
4025 /* Expand and convert an Exim list to an ALPN list. False return for fail.
4026 NULL plist return for silent no-ALPN.
4028 Overwite the passed-in list with the expanded version.
4032 tls_alpn_plist(uschar ** tls_alpn, const uschar ** plist, unsigned * plen,
4037 if (!expand_check(*tls_alpn, US"tls_alpn", &exp_alpn, errstr))
4039 *tls_alpn = exp_alpn;
4043 DEBUG(D_tls) debug_printf("Setting TLS ALPN forced to fail, not sending\n");
4048 /* The server implementation only accepts exactly one protocol name
4049 but it's little extra code complexity in the client. */
4051 const uschar * list = exp_alpn;
4052 uschar * p = store_get(Ustrlen(exp_alpn), exp_alpn), * s, * t;
4056 for (t = p; s = string_nextinlist(&list, &sep, NULL, 0); t += len)
4058 *t++ = len = (uschar) Ustrlen(s);
4061 *plist = (*plen = t - p) ? p : NULL;
4065 #endif /* EXIM_HAVE_ALPN */
4068 /*************************************************
4069 * Start a TLS session in a client *
4070 *************************************************/
4072 /* Called from the smtp transport after STARTTLS has been accepted.
4075 cctx connection context
4076 conn_args connection details
4077 cookie datum for randomness; can be NULL
4078 tlsp record details of TLS channel configuration here; must be non-NULL
4079 errstr error string pointer
4081 Returns: TRUE for success with TLS session context set in connection context,
4086 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
4087 void * cookie, tls_support * tlsp, uschar ** errstr)
4089 host_item * host = conn_args->host; /* for msgs and option-tests */
4090 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
4091 smtp_transport_options_block * ob = tb
4092 ? (smtp_transport_options_block *)tb->options_block
4093 : &smtp_transport_option_defaults;
4094 exim_openssl_client_tls_ctx * exim_client_ctx;
4095 uschar * expciphers;
4097 static uschar peerdn[256];
4099 #ifndef DISABLE_OCSP
4100 BOOL request_ocsp = FALSE;
4101 BOOL require_ocsp = FALSE;
4105 store_pool = POOL_PERM;
4106 exim_client_ctx = store_get(sizeof(exim_openssl_client_tls_ctx), GET_UNTAINTED);
4107 exim_client_ctx->corked = NULL;
4111 tlsp->tlsa_usage = 0;
4114 #ifndef DISABLE_OCSP
4116 # ifdef SUPPORT_DANE
4117 if ( conn_args->dane
4118 && ob->hosts_request_ocsp[0] == '*'
4119 && ob->hosts_request_ocsp[1] == '\0'
4122 /* Unchanged from default. Use a safer one under DANE */
4123 request_ocsp = TRUE;
4124 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
4125 " {= {4}{$tls_out_tlsa_usage}} } "
4131 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK))
4132 request_ocsp = TRUE;
4134 # ifdef SUPPORT_DANE
4138 verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
4140 # if defined(SUPPORT_DANE) && !defined(EXIM_HAVE_OPENSSL_OCSP_RESP_GET0_SIGNER)
4141 if (conn_args->dane && (require_ocsp || request_ocsp))
4143 DEBUG(D_tls) debug_printf("OpenSSL version to early to combine OCSP"
4144 " and DANE; disabling OCSP\n");
4145 require_ocsp = request_ocsp = FALSE;
4151 rc = tls_init(host, ob,
4152 #ifndef DISABLE_OCSP
4153 (void *)(long)request_ocsp,
4155 cookie, &client_static_state, tlsp, errstr);
4156 if (rc != OK) return FALSE;
4158 exim_client_ctx->ctx = client_static_state->lib_state.lib_ctx;
4160 tlsp->certificate_verified = FALSE;
4161 client_verify_callback_called = FALSE;
4165 if (conn_args->dane)
4167 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
4168 other failures should be treated as problems. */
4169 if (ob->dane_require_tls_ciphers &&
4170 !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
4171 &expciphers, errstr))
4173 if (expciphers && *expciphers == '\0')
4176 normalise_ciphers(&expciphers, ob->dane_require_tls_ciphers);
4181 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
4182 &expciphers, errstr))
4185 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
4186 are separated by underscores. So that I can use either form in my tests, and
4187 also for general convenience, we turn underscores into hyphens here. */
4189 normalise_ciphers(&expciphers, ob->tls_require_ciphers);
4194 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
4195 if (!SSL_CTX_set_cipher_list(exim_client_ctx->ctx, CS expciphers))
4197 tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
4203 if (conn_args->dane)
4205 SSL_CTX_set_verify(exim_client_ctx->ctx,
4206 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
4207 verify_callback_client_dane);
4209 if (!DANESSL_library_init())
4211 tls_error(US"library init", host, NULL, errstr);
4214 if (DANESSL_CTX_init(exim_client_ctx->ctx) <= 0)
4216 tls_error(US"context init", host, NULL, errstr);
4219 DEBUG(D_tls) debug_printf("since dane-mode conn, not loading the usual CA bundle\n");
4225 if (tls_client_basic_ctx_init(exim_client_ctx->ctx, host, ob,
4226 client_static_state, errstr) != OK)
4231 if (!expand_check(ob->tls_sni, US"tls_sni", &tlsp->sni, errstr))
4234 { DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n"); }
4235 else if (!Ustrlen(tlsp->sni))
4239 #ifndef EXIM_HAVE_OPENSSL_TLSEXT
4240 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
4248 #ifdef EXIM_HAVE_ALPN
4250 const uschar * plist;
4253 if (!tls_alpn_plist(&ob->tls_alpn, &plist, &plen, errstr))
4256 if (SSL_CTX_set_alpn_protos(exim_client_ctx->ctx, plist, plen) != 0)
4258 tls_error(US"alpn init", host, NULL, errstr);
4262 DEBUG(D_tls) debug_printf("Setting TLS ALPN '%s'\n", ob->tls_alpn);
4265 log_write(0, LOG_MAIN, "ALPN unusable with this OpenSSL library version; ignoring \"%s\"\n",
4269 #ifndef DISABLE_TLS_RESUME
4270 /*XXX have_lbserver: another cmdline arg possibly, for continued-conn, but use
4271 will be very low. */
4273 if (!conn_args->have_lbserver) /* wanted for tls_client_resmption_key() */
4274 { DEBUG(D_tls) debug_printf("resumption not supported on continued-connection\n"); }
4275 else if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
4276 tls_client_ctx_resume_prehandshake(exim_client_ctx, conn_args, tlsp, ob);
4280 if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx)))
4282 tls_error(US"SSL_new", host, NULL, errstr);
4285 SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx));
4286 SSL_set_fd(exim_client_ctx->ssl, cctx->sock);
4287 SSL_set_connect_state(exim_client_ctx->ssl);
4289 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
4292 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tlsp->sni);
4293 SSL_set_tlsext_host_name(exim_client_ctx->ssl, tlsp->sni);
4298 if (conn_args->dane)
4299 if (dane_tlsa_load(exim_client_ctx->ssl, host, &conn_args->tlsa_dnsa, errstr) != OK)
4303 #ifndef DISABLE_OCSP
4304 /* Request certificate status at connection-time. If the server
4305 does OCSP stapling we will get the callback (set in tls_init()) */
4306 # ifdef SUPPORT_DANE
4310 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
4311 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
4313 { /* Re-eval now $tls_out_tlsa_usage is populated. If
4314 this means we avoid the OCSP request, we wasted the setup
4315 cost in tls_init(). */
4316 require_ocsp = verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
4317 request_ocsp = require_ocsp
4318 || verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
4325 SSL_set_tlsext_status_type(exim_client_ctx->ssl, TLSEXT_STATUSTYPE_ocsp);
4326 client_static_state->u_ocsp.client.verify_required = require_ocsp;
4327 tlsp->ocsp = OCSP_NOT_RESP;
4331 #ifndef DISABLE_TLS_RESUME
4332 if (!tls_client_ssl_resume_prehandshake(exim_client_ctx->ssl, tlsp, host,
4337 #ifndef DISABLE_EVENT
4338 client_static_state->event_action = tb ? tb->event_action : NULL;
4341 /* There doesn't seem to be a built-in timeout on connection. */
4343 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
4344 sigalrm_seen = FALSE;
4345 ALARM(ob->command_timeout);
4346 rc = SSL_connect(exim_client_ctx->ssl);
4350 if (conn_args->dane)
4351 DANESSL_cleanup(exim_client_ctx->ssl);
4356 #ifndef DISABLE_OCSP
4357 if (client_static_state->u_ocsp.client.verify_errstr)
4358 { if (errstr) *errstr = client_static_state->u_ocsp.client.verify_errstr; }
4361 tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, errstr);
4367 debug_printf("SSL_connect succeeded\n");
4368 tls_dump_keylog(exim_client_ctx->ssl);
4371 #ifndef DISABLE_TLS_RESUME
4372 tls_client_resume_posthandshake(exim_client_ctx, tlsp);
4375 #ifdef EXIM_HAVE_ALPN
4376 if (ob->tls_alpn) /* We requested. See what was negotiated. */
4378 const uschar * name;
4381 SSL_get0_alpn_selected(exim_client_ctx->ssl, &name, &len);
4383 { DEBUG(D_tls) debug_printf("ALPN negotiated %u: '%.*s'\n", len, (int)*name, name+1); }
4384 else if (verify_check_given_host(CUSS &ob->hosts_require_alpn, host) == OK)
4386 /* Would like to send a relevant fatal Alert, but OpenSSL has no API */
4387 tls_error(US"handshake", host, US"ALPN required but not negotiated", errstr);
4393 #ifdef SSL_get_extms_support
4394 tlsp->ext_master_secret = SSL_get_extms_support(exim_client_ctx->ssl) == 1;
4396 peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn));
4398 tlsp->ver = tlsver_name(exim_client_ctx->ssl);
4399 tlsp->cipher = construct_cipher_name(exim_client_ctx->ssl, tlsp->ver, &tlsp->bits);
4400 tlsp->cipher_stdname = cipher_stdname_ssl(exim_client_ctx->ssl);
4402 /* Record the certificate we presented */
4404 X509 * crt = SSL_get_certificate(exim_client_ctx->ssl);
4405 tlsp->ourcert = crt ? X509_dup(crt) : NULL;
4408 /*XXX will this work with continued-TLS? */
4409 tls_get_channel_binding(exim_client_ctx->ssl, tlsp, GET_TAINTED);
4411 tlsp->active.sock = cctx->sock;
4412 tlsp->active.tls_ctx = exim_client_ctx;
4413 cctx->tls_ctx = exim_client_ctx;
4422 tls_refill(unsigned lim)
4424 SSL * ssl = state_server.lib_state.lib_ssl;
4428 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
4429 ssl_xfer_buffer, ssl_xfer_buffer_size);
4432 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
4433 inbytes = SSL_read(ssl, CS ssl_xfer_buffer,
4434 MIN(ssl_xfer_buffer_size, lim));
4435 error = SSL_get_error(ssl, inbytes);
4436 if (smtp_receive_timeout > 0) ALARM_CLR(0);
4438 if (had_command_timeout) /* set by signal handler */
4439 smtp_command_timeout_exit(); /* does not return */
4440 if (had_command_sigterm)
4441 smtp_command_sigterm_exit();
4442 if (had_data_timeout)
4443 smtp_data_timeout_exit();
4444 if (had_data_sigint)
4445 smtp_data_sigint_exit();
4447 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
4448 closed down, not that the socket itself has been closed down. Revert to
4449 non-SSL handling. */
4453 case SSL_ERROR_NONE:
4456 case SSL_ERROR_ZERO_RETURN:
4457 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
4459 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
4462 tls_close(NULL, TLS_NO_SHUTDOWN);
4465 /* Handle genuine errors */
4467 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4468 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
4469 ssl_xfer_error = TRUE;
4473 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
4474 DEBUG(D_tls) if (error == SSL_ERROR_SYSCALL)
4475 debug_printf(" - syscall %s\n", strerror(errno));
4476 ssl_xfer_error = TRUE;
4480 #ifndef DISABLE_DKIM
4481 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
4483 ssl_xfer_buffer_hwm = inbytes;
4484 ssl_xfer_buffer_lwm = 0;
4489 /*************************************************
4490 * TLS version of getc *
4491 *************************************************/
4493 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
4494 it refills the buffer via the SSL reading function.
4496 Arguments: lim Maximum amount to read/buffer
4497 Returns: the next character or EOF
4499 Only used by the server-side TLS.
4503 tls_getc(unsigned lim)
4505 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
4506 if (!tls_refill(lim))
4507 return ssl_xfer_error ? EOF : smtp_getc(lim);
4509 /* Something in the buffer; return next uschar */
4511 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
4517 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm;
4521 tls_getbuf(unsigned * len)
4526 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
4527 if (!tls_refill(*len))
4529 if (!ssl_xfer_error) return smtp_getbuf(len);
4534 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
4536 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
4537 ssl_xfer_buffer_lwm += size;
4544 tls_get_cache(unsigned lim)
4546 #ifndef DISABLE_DKIM
4547 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
4551 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
4557 tls_could_getc(void)
4559 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm
4560 || SSL_pending(state_server.lib_state.lib_ssl) > 0;
4564 /*************************************************
4565 * Read bytes from TLS channel *
4566 *************************************************/
4570 ct_ctx client context pointer, or NULL for the one global server context
4574 Returns: the number of bytes read
4575 -1 after a failed read, including EOF
4577 Only used by the client-side TLS.
4581 tls_read(void * ct_ctx, uschar *buff, size_t len)
4583 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
4584 : state_server.lib_state.lib_ssl;
4588 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
4589 buff, (unsigned int)len);
4592 inbytes = SSL_read(ssl, CS buff, len);
4593 error = SSL_get_error(ssl, inbytes);
4595 if (error == SSL_ERROR_ZERO_RETURN)
4597 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
4600 else if (error != SSL_ERROR_NONE)
4610 /*************************************************
4611 * Write bytes down TLS channel *
4612 *************************************************/
4616 ct_ctx client context pointer, or NULL for the one global server context
4619 more further data expected soon
4621 Returns: the number of bytes after a successful write,
4622 -1 after a failed write
4624 Used by both server-side and client-side TLS. Calling with len zero and more unset
4625 will flush buffered writes; buff can be null for this case.
4629 tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
4632 int outbytes, error;
4634 ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
4635 : state_server.lib_state.lib_ssl;
4636 static gstring * server_corked = NULL;
4637 gstring ** corkedp = ct_ctx
4638 ? &((exim_openssl_client_tls_ctx *)ct_ctx)->corked : &server_corked;
4639 gstring * corked = *corkedp;
4641 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
4642 buff, (unsigned long)len, more ? ", more" : "");
4644 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
4645 "more" is notified. This hack is only ok if small amounts are involved AND only
4646 one stream does it, in one context (i.e. no store reset). Currently it is used
4647 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only.
4648 We support callouts done by the server process by using a separate client
4649 context for the stashed information. */
4650 /* + if PIPE_COMMAND, banner & ehlo-resp for smmtp-on-connect. Suspect there's
4651 a store reset there, so use POOL_PERM. */
4652 /* + if CHUNKING, cmds EHLO,MAIL,RCPT(s),BDAT */
4656 if (!len) buff = US &error; /* dummy just so that string_catn is ok */
4658 int save_pool = store_pool;
4659 store_pool = POOL_PERM;
4661 corked = string_catn(corked, buff, len);
4663 store_pool = save_pool;
4670 buff = CUS corked->s;
4675 for (int left = len; left > 0;)
4677 DEBUG(D_tls) debug_printf("SSL_write(%p, %p, %d)\n", ssl, buff, left);
4679 outbytes = SSL_write(ssl, CS buff, left);
4680 error = SSL_get_error(ssl, outbytes);
4681 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
4684 case SSL_ERROR_NONE: /* the usual case */
4690 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4691 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
4694 case SSL_ERROR_ZERO_RETURN:
4695 log_write(0, LOG_MAIN, "SSL channel closed on write");
4698 case SSL_ERROR_SYSCALL:
4699 if (ct_ctx || errno != ECONNRESET || !f.smtp_in_quit)
4700 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
4701 sender_fullhost ? sender_fullhost : US"<unknown>",
4703 else if (LOGGING(protocol_detail))
4704 log_write(0, LOG_MAIN, "[%s] after QUIT, client reset TCP before"
4705 " SMTP response and TLS close\n", sender_host_address);
4707 DEBUG(D_tls) debug_printf("[%s] SSL_write: after QUIT,"
4708 " client reset TCP before TLS close\n", sender_host_address);
4712 log_write(0, LOG_MAIN, "SSL_write error %d", error);
4723 ct_ctx client TLS context pointer, or NULL for the one global server context
4727 tls_shutdown_wr(void * ct_ctx)
4729 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4730 SSL ** sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4731 int * fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4734 if (*fdp < 0) return; /* TLS was not active */
4736 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
4738 HDEBUG(D_transport|D_tls|D_acl|D_v) debug_printf_indent(" SMTP(TLS shutdown)>>\n");
4739 rc = SSL_shutdown(*sslp);
4740 if (rc < 0) DEBUG(D_tls)
4742 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4743 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4747 /*************************************************
4748 * Close down a TLS session *
4749 *************************************************/
4751 /* This is also called from within a delivery subprocess forked from the
4752 daemon, to shut down the TLS library, without actually doing a shutdown (which
4753 would tamper with the SSL session in the parent process).
4756 ct_ctx client TLS context pointer, or NULL for the one global server context
4757 do_shutdown 0 no data-flush or TLS close-alert
4758 1 if TLS close-alert is to be sent,
4759 2 if also response to be waited for
4763 Used by both server-side and client-side TLS.
4767 tls_close(void * ct_ctx, int do_shutdown)
4769 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4770 SSL ** sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4771 int * fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4773 if (*fdp < 0) return; /* TLS was not active */
4775 if (do_shutdown > TLS_NO_SHUTDOWN)
4778 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
4779 do_shutdown > TLS_SHUTDOWN_NOWAIT ? " (with response-wait)" : "");
4781 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
4783 if ( ( do_shutdown >= TLS_SHUTDOWN_WONLY
4784 || (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
4786 && do_shutdown > TLS_SHUTDOWN_NOWAIT
4789 #ifdef EXIM_TCP_CORK
4790 (void) setsockopt(*fdp, IPPROTO_TCP, EXIM_TCP_CORK, US &off, sizeof(off));
4793 rc = SSL_shutdown(*sslp); /* wait for response */
4797 if (rc < 0) DEBUG(D_tls)
4799 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4800 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4804 if (!o_ctx) /* server side */
4806 #ifndef DISABLE_OCSP
4807 sk_X509_pop_free(state_server.u_ocsp.server.verify_stack, X509_free);
4808 state_server.u_ocsp.server.verify_stack = NULL;
4811 receive_getc = smtp_getc;
4812 receive_getbuf = smtp_getbuf;
4813 receive_get_cache = smtp_get_cache;
4814 receive_hasc = smtp_hasc;
4815 receive_ungetc = smtp_ungetc;
4816 receive_feof = smtp_feof;
4817 receive_ferror = smtp_ferror;
4818 tls_in.active.tls_ctx = NULL;
4820 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
4831 /*************************************************
4832 * Let tls_require_ciphers be checked at startup *
4833 *************************************************/
4835 /* The tls_require_ciphers option, if set, must be something which the
4838 Returns: NULL on success, or error message
4842 tls_validate_require_cipher(void)
4845 uschar * expciphers, * err;
4849 if (!(tls_require_ciphers && *tls_require_ciphers))
4852 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
4854 return US"failed to expand tls_require_ciphers";
4856 if (!(expciphers && *expciphers))
4859 normalise_ciphers(&expciphers, tls_require_ciphers);
4862 if (lib_ctx_new(&ctx, NULL, &err) == OK)
4865 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
4867 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
4869 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4870 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
4871 expciphers, ssl_errstring);
4882 /*************************************************
4883 * Report the library versions. *
4884 *************************************************/
4886 /* There have historically been some issues with binary compatibility in
4887 OpenSSL libraries; if Exim (like many other applications) is built against
4888 one version of OpenSSL but the run-time linker picks up another version,
4889 it can result in serious failures, including crashing with a SIGSEGV. So
4890 report the version found by the compiler and the run-time version.
4892 Note: some OS vendors backport security fixes without changing the version
4893 number/string, and the version date remains unchanged. The _build_ date
4894 will change, so we can more usefully assist with version diagnosis by also
4895 reporting the build date.
4897 Arguments: string to append to
4902 tls_version_report(gstring * g)
4904 return string_fmt_append(g,
4905 "Library version: OpenSSL: Compile: %s\n"
4908 OPENSSL_VERSION_TEXT,
4909 SSLeay_version(SSLEAY_VERSION),
4910 SSLeay_version(SSLEAY_BUILT_ON));
4911 /* third line is 38 characters for the %s and the line is 73 chars long;
4912 the OpenSSL output includes a "built on: " prefix already. */
4918 /*************************************************
4919 * Random number generation *
4920 *************************************************/
4922 /* Pseudo-random number generation. The result is not expected to be
4923 cryptographically strong but not so weak that someone will shoot themselves
4924 in the foot using it as a nonce in input in some email header scheme or
4925 whatever weirdness they'll twist this into. The result should handle fork()
4926 and avoid repeating sequences. OpenSSL handles that for us.
4930 Returns a random number in range [0, max-1]
4934 vaguely_random_number(int max)
4938 static pid_t pidlast = 0;
4940 uschar smallbuf[sizeof(r)];
4946 if (pidnow != pidlast)
4948 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
4949 is unique for each thread", this doesn't apparently apply across processes,
4950 so our own warning from vaguely_random_number_fallback() applies here too.
4951 Fix per PostgreSQL. */
4957 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
4961 gettimeofday(&r.tv, NULL);
4964 RAND_seed(US (&r), sizeof(r));
4966 /* We're after pseudo-random, not random; if we still don't have enough data
4967 in the internal PRNG then our options are limited. We could sleep and hope
4968 for entropy to come along (prayer technique) but if the system is so depleted
4969 in the first place then something is likely to just keep taking it. Instead,
4970 we'll just take whatever little bit of pseudo-random we can still manage to
4973 needed_len = sizeof(r);
4974 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
4975 asked for a number less than 10. */
4976 for (r = max, i = 0; r; ++i)
4982 #ifdef EXIM_HAVE_RAND_PSEUDO
4983 /* We do not care if crypto-strong */
4984 i = RAND_pseudo_bytes(smallbuf, needed_len);
4986 i = RAND_bytes(smallbuf, needed_len);
4992 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
4993 return vaguely_random_number_fallback(max);
4997 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
5000 /* We don't particularly care about weighted results; if someone wants
5001 smooth distribution and cares enough then they should submit a patch then. */
5008 /*************************************************
5009 * OpenSSL option parse *
5010 *************************************************/
5012 /* Parse one option for tls_openssl_options_parse below
5015 name one option name
5016 value place to store a value for it
5017 Returns success or failure in parsing
5023 tls_openssl_one_option_parse(uschar *name, long *value)
5026 int last = exim_openssl_options_size;
5027 while (last > first)
5029 int middle = (first + last)/2;
5030 int c = Ustrcmp(name, exim_openssl_options[middle].name);
5033 *value = exim_openssl_options[middle].value;
5047 /*************************************************
5048 * OpenSSL option parsing logic *
5049 *************************************************/
5051 /* OpenSSL has a number of compatibility options which an administrator might
5052 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
5053 we look like log_selector.
5056 option_spec the administrator-supplied string of options
5057 results ptr to long storage for the options bitmap
5058 Returns success or failure
5062 tls_openssl_options_parse(uschar *option_spec, long *results)
5065 uschar * exp, * end;
5066 BOOL adding, item_parsed;
5068 /* Server: send no (<= TLS1.2) session tickets */
5069 result = SSL_OP_NO_TICKET;
5071 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
5072 from default because it increases BEAST susceptibility. */
5073 #ifdef SSL_OP_NO_SSLv2
5074 result |= SSL_OP_NO_SSLv2;
5076 #ifdef SSL_OP_NO_SSLv3
5077 result |= SSL_OP_NO_SSLv3;
5079 #ifdef SSL_OP_SINGLE_DH_USE
5080 result |= SSL_OP_SINGLE_DH_USE;
5082 #ifdef SSL_OP_NO_RENEGOTIATION
5083 result |= SSL_OP_NO_RENEGOTIATION;
5092 if (!expand_check(option_spec, US"openssl_options", &exp, &end))
5095 for (uschar * s = exp; *s; /**/)
5097 while (isspace(*s)) ++s;
5100 if (*s != '+' && *s != '-')
5102 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
5103 "+ or - expected but found \"%s\"\n", s);
5106 adding = *s++ == '+';
5107 for (end = s; *end && !isspace(*end); ) end++;
5108 item_parsed = tls_openssl_one_option_parse(string_copyn(s, end-s), &item);
5111 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
5114 DEBUG(D_tls) debug_printf("openssl option, %s %08lx: %08lx (%s)\n",
5115 adding ? "adding to " : "removing from", result, item, s);
5127 #endif /*!MACRO_PREDEF*/
5130 /* End of tls-openssl.c */