1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2019 */
6 /* See the file NOTICE for conditions of use and distribution. */
8 /* Portions Copyright (c) The OpenSSL Project 1999 */
10 /* This module provides the TLS (aka SSL) support for Exim using the OpenSSL
11 library. It is #included into the tls.c file when that library is used. The
12 code herein is based on a patch that was originally contributed by Steve
13 Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara.
15 No cryptographic code is included in Exim. All this module does is to call
16 functions from the OpenSSL library. */
21 #include <openssl/lhash.h>
22 #include <openssl/ssl.h>
23 #include <openssl/err.h>
24 #include <openssl/rand.h>
25 #ifndef OPENSSL_NO_ECDH
26 # include <openssl/ec.h>
29 # include <openssl/ocsp.h>
37 # define EXIM_OCSP_SKEW_SECONDS (300L)
38 # define EXIM_OCSP_MAX_AGE (-1L)
41 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
42 # define EXIM_HAVE_OPENSSL_TLSEXT
44 #if OPENSSL_VERSION_NUMBER >= 0x00908000L
45 # define EXIM_HAVE_RSA_GENKEY_EX
47 #if OPENSSL_VERSION_NUMBER >= 0x10100000L
48 # define EXIM_HAVE_OCSP_RESP_COUNT
49 # define OPENSSL_AUTO_SHA256
51 # define EXIM_HAVE_EPHEM_RSA_KEX
52 # define EXIM_HAVE_RAND_PSEUDO
54 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
55 # define EXIM_HAVE_SHA256
58 /* X509_check_host provides sane certificate hostname checking, but was added
59 to OpenSSL late, after other projects forked off the code-base. So in
60 addition to guarding against the base version number, beware that LibreSSL
61 does not (at this time) support this function.
63 If LibreSSL gains a different API, perhaps via libtls, then we'll probably
64 opt to disentangle and ask a LibreSSL user to provide glue for a third
65 crypto provider for libtls instead of continuing to tie the OpenSSL glue
66 into even twistier knots. If LibreSSL gains the same API, we can just
67 change this guard and punt the issue for a while longer. */
69 #ifndef LIBRESSL_VERSION_NUMBER
70 # if OPENSSL_VERSION_NUMBER >= 0x010100000L
71 # define EXIM_HAVE_OPENSSL_CHECKHOST
72 # define EXIM_HAVE_OPENSSL_DH_BITS
73 # define EXIM_HAVE_OPENSSL_TLS_METHOD
74 # define EXIM_HAVE_OPENSSL_KEYLOG
75 # define EXIM_HAVE_OPENSSL_CIPHER_GET_ID
76 # define EXIM_HAVE_SESSION_TICKET
77 # define EXIM_HAVE_OPESSL_TRACE
78 # define EXIM_HAVE_OPESSL_GET0_SERIAL
80 # define EXIM_NEED_OPENSSL_INIT
82 # if OPENSSL_VERSION_NUMBER >= 0x010000000L \
83 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
84 # define EXIM_HAVE_OPENSSL_CHECKHOST
88 #if !defined(LIBRESSL_VERSION_NUMBER) \
89 || LIBRESSL_VERSION_NUMBER >= 0x20010000L
90 # if !defined(OPENSSL_NO_ECDH)
91 # if OPENSSL_VERSION_NUMBER >= 0x0090800fL
92 # define EXIM_HAVE_ECDH
94 # if OPENSSL_VERSION_NUMBER >= 0x10002000L
95 # define EXIM_HAVE_OPENSSL_EC_NIST2NID
100 #ifndef LIBRESSL_VERSION_NUMBER
101 # if OPENSSL_VERSION_NUMBER >= 0x010101000L
102 # define OPENSSL_HAVE_KEYLOG_CB
103 # define OPENSSL_HAVE_NUM_TICKETS
104 # define EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
108 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
109 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
110 # define DISABLE_OCSP
113 #ifdef EXPERIMENTAL_TLS_RESUME
114 # if OPENSSL_VERSION_NUMBER < 0x0101010L
115 # error OpenSSL version too old for session-resumption
119 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
120 # include <openssl/x509v3.h>
123 #ifndef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
124 # ifndef EXIM_HAVE_OPENSSL_CIPHER_GET_ID
125 # define SSL_CIPHER_get_id(c) (c->id)
127 # ifndef MACRO_PREDEF
128 # include "tls-cipher-stdname.c"
132 /*************************************************
133 * OpenSSL option parse *
134 *************************************************/
136 typedef struct exim_openssl_option {
139 } exim_openssl_option;
140 /* We could use a macro to expand, but we need the ifdef and not all the
141 options document which version they were introduced in. Policylet: include
142 all options unless explicitly for DTLS, let the administrator choose which
145 This list is current as of:
147 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
148 Plus SSL_OP_NO_TLSv1_3 for 1.1.2-dev
150 static exim_openssl_option exim_openssl_options[] = {
151 /* KEEP SORTED ALPHABETICALLY! */
153 { US"all", (long) SSL_OP_ALL },
155 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
156 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
158 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
159 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
161 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
162 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
164 #ifdef SSL_OP_EPHEMERAL_RSA
165 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
167 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
168 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
170 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
171 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
173 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
174 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
176 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
177 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
179 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
180 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
182 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
183 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
185 #ifdef SSL_OP_NO_COMPRESSION
186 { US"no_compression", SSL_OP_NO_COMPRESSION },
188 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
189 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
191 #ifdef SSL_OP_NO_SSLv2
192 { US"no_sslv2", SSL_OP_NO_SSLv2 },
194 #ifdef SSL_OP_NO_SSLv3
195 { US"no_sslv3", SSL_OP_NO_SSLv3 },
197 #ifdef SSL_OP_NO_TICKET
198 { US"no_ticket", SSL_OP_NO_TICKET },
200 #ifdef SSL_OP_NO_TLSv1
201 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
203 #ifdef SSL_OP_NO_TLSv1_1
204 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
205 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
206 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
208 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
211 #ifdef SSL_OP_NO_TLSv1_2
212 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
214 #ifdef SSL_OP_NO_TLSv1_3
215 { US"no_tlsv1_3", SSL_OP_NO_TLSv1_3 },
217 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
218 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
220 #ifdef SSL_OP_SINGLE_DH_USE
221 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
223 #ifdef SSL_OP_SINGLE_ECDH_USE
224 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
226 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
227 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
229 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
230 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
232 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
233 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
235 #ifdef SSL_OP_TLS_D5_BUG
236 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
238 #ifdef SSL_OP_TLS_ROLLBACK_BUG
239 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
244 static int exim_openssl_options_size = nelem(exim_openssl_options);
253 for (struct exim_openssl_option * o = exim_openssl_options;
254 o < exim_openssl_options + nelem(exim_openssl_options); o++)
256 /* Trailing X is workaround for problem with _OPT_OPENSSL_NO_TLSV1
257 being a ".ifdef _OPT_OPENSSL_NO_TLSV1_3" match */
259 spf(buf, sizeof(buf), US"_OPT_OPENSSL_%T_X", o->name);
260 builtin_macro_create(buf);
263 # ifdef EXPERIMENTAL_TLS_RESUME
264 builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING );
266 # ifdef SSL_OP_NO_TLSv1_3
267 builtin_macro_create(US"_HAVE_TLS1_3");
272 /******************************************************************************/
274 /* Structure for collecting random data for seeding. */
276 typedef struct randstuff {
281 /* Local static variables */
283 static BOOL client_verify_callback_called = FALSE;
284 static BOOL server_verify_callback_called = FALSE;
285 static const uschar *sid_ctx = US"exim";
287 /* We have three different contexts to care about.
289 Simple case: client, `client_ctx`
290 As a client, we can be doing a callout or cut-through delivery while receiving
291 a message. So we have a client context, which should have options initialised
292 from the SMTP Transport. We may also concurrently want to make TLS connections
293 to utility daemons, so client-contexts are allocated and passed around in call
294 args rather than using a gobal.
297 There are two cases: with and without ServerNameIndication from the client.
298 Given TLS SNI, we can be using different keys, certs and various other
299 configuration settings, because they're re-expanded with $tls_sni set. This
300 allows vhosting with TLS. This SNI is sent in the handshake.
301 A client might not send SNI, so we need a fallback, and an initial setup too.
302 So as a server, we start out using `server_ctx`.
303 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
304 `server_sni` from `server_ctx` and then initialise settings by re-expanding
312 } exim_openssl_client_tls_ctx;
314 static SSL_CTX *server_ctx = NULL;
315 static SSL *server_ssl = NULL;
317 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
318 static SSL_CTX *server_sni = NULL;
321 static char ssl_errstring[256];
323 static int ssl_session_timeout = 7200; /* Two hours */
324 static BOOL client_verify_optional = FALSE;
325 static BOOL server_verify_optional = FALSE;
327 static BOOL reexpand_tls_files_for_sni = FALSE;
330 typedef struct ocsp_resp {
331 struct ocsp_resp * next;
332 OCSP_RESPONSE * resp;
335 typedef struct tls_ext_ctx_cb {
341 STACK_OF(X509) *verify_stack; /* chain for verifying the proof */
345 const uschar *file_expanded;
346 ocsp_resplist *olist;
349 X509_STORE *verify_store; /* non-null if status requested */
350 BOOL verify_required;
355 /* these are cached from first expand */
356 uschar *server_cipher_list;
357 /* only passed down to tls_error: */
359 const uschar * verify_cert_hostnames;
360 #ifndef DISABLE_EVENT
361 uschar * event_action;
365 /* should figure out a cleanup of API to handle state preserved per
366 implementation, for various reasons, which can be void * in the APIs.
367 For now, we hack around it. */
368 tls_ext_ctx_cb *client_static_cbinfo = NULL; /*XXX should not use static; multiple concurrent clients! */
369 tls_ext_ctx_cb *server_static_cbinfo = NULL;
372 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
373 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr );
376 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
377 static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
380 static int tls_server_stapling_cb(SSL *s, void *arg);
385 /* Daemon-called, before every connection, key create/rotate */
386 #ifdef EXPERIMENTAL_TLS_RESUME
387 static void tk_init(void);
388 static int tls_exdata_idx = -1;
392 tls_daemon_init(void)
394 #ifdef EXPERIMENTAL_TLS_RESUME
401 /*************************************************
403 *************************************************/
405 /* Called from lots of places when errors occur before actually starting to do
406 the TLS handshake, that is, while the session is still in clear. Always returns
407 DEFER for a server and FAIL for a client so that most calls can use "return
408 tls_error(...)" to do this processing and then give an appropriate return. A
409 single function is used for both server and client, because it is called from
410 some shared functions.
413 prefix text to include in the logged error
414 host NULL if setting up a server;
415 the connected host if setting up a client
416 msg error message or NULL if we should ask OpenSSL
417 errstr pointer to output error message
419 Returns: OK/DEFER/FAIL
423 tls_error(uschar * prefix, const host_item * host, uschar * msg, uschar ** errstr)
427 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
428 msg = US ssl_errstring;
431 msg = string_sprintf("(%s): %s", prefix, msg);
432 DEBUG(D_tls) debug_printf("TLS error '%s'\n", msg);
433 if (errstr) *errstr = msg;
434 return host ? FAIL : DEFER;
439 /*************************************************
440 * Callback to generate RSA key *
441 *************************************************/
445 s SSL connection (not used)
449 Returns: pointer to generated key
453 rsa_callback(SSL *s, int export, int keylength)
456 #ifdef EXIM_HAVE_RSA_GENKEY_EX
457 BIGNUM *bn = BN_new();
460 export = export; /* Shut picky compilers up */
461 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
463 #ifdef EXIM_HAVE_RSA_GENKEY_EX
464 if ( !BN_set_word(bn, (unsigned long)RSA_F4)
465 || !(rsa_key = RSA_new())
466 || !RSA_generate_key_ex(rsa_key, keylength, bn, NULL)
469 if (!(rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL)))
473 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
474 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
486 x509_store_dump_cert_s_names(X509_STORE * store)
488 STACK_OF(X509_OBJECT) * roots= store->objs;
489 static uschar name[256];
491 for (int i= 0; i < sk_X509_OBJECT_num(roots); i++)
493 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
494 if(tmp_obj->type == X509_LU_X509)
496 X509_NAME * sn = X509_get_subject_name(tmp_obj->data.x509);
497 if (X509_NAME_oneline(sn, CS name, sizeof(name)))
499 name[sizeof(name)-1] = '\0';
500 debug_printf(" %s\n", name);
509 #ifndef DISABLE_EVENT
511 verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
512 BOOL *calledp, const BOOL *optionalp, const uschar * what)
518 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
521 DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth);
522 old_cert = tlsp->peercert;
523 tlsp->peercert = X509_dup(cert);
524 /* NB we do not bother setting peerdn */
525 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
527 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
528 "depth=%d cert=%s: %s",
529 tlsp == &tls_out ? deliver_host_address : sender_host_address,
530 what, depth, dn, yield);
534 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
535 return 1; /* reject (leaving peercert set) */
537 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
538 "(host in tls_try_verify_hosts)\n");
539 tlsp->verify_override = TRUE;
541 X509_free(tlsp->peercert);
542 tlsp->peercert = old_cert;
548 /*************************************************
549 * Callback for verification *
550 *************************************************/
552 /* The SSL library does certificate verification if set up to do so. This
553 callback has the current yes/no state is in "state". If verification succeeded,
554 we set the certificate-verified flag. If verification failed, what happens
555 depends on whether the client is required to present a verifiable certificate
558 If verification is optional, we change the state to yes, but still log the
559 verification error. For some reason (it really would help to have proper
560 documentation of OpenSSL), this callback function then gets called again, this
561 time with state = 1. We must take care not to set the private verified flag on
562 the second time through.
564 Note: this function is not called if the client fails to present a certificate
565 when asked. We get here only if a certificate has been received. Handling of
566 optional verification for this case is done when requesting SSL to verify, by
567 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
569 May be called multiple times for different issues with a certificate, even
570 for a given "depth" in the certificate chain.
573 preverify_ok current yes/no state as 1/0
574 x509ctx certificate information.
575 tlsp per-direction (client vs. server) support data
576 calledp has-been-called flag
577 optionalp verification-is-optional flag
579 Returns: 0 if verification should fail, otherwise 1
583 verify_callback(int preverify_ok, X509_STORE_CTX * x509ctx,
584 tls_support * tlsp, BOOL * calledp, BOOL * optionalp)
586 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
587 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
590 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
592 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
593 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
594 tlsp == &tls_out ? deliver_host_address : sender_host_address);
597 dn[sizeof(dn)-1] = '\0';
599 tlsp->verify_override = FALSE;
600 if (preverify_ok == 0)
602 uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])",
603 *verify_mode, sender_host_address)
605 log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
606 tlsp == &tls_out ? deliver_host_address : sender_host_address,
608 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn);
613 tlsp->peercert = X509_dup(cert); /* record failing cert */
614 return 0; /* reject */
616 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
617 "tls_try_verify_hosts)\n");
618 tlsp->verify_override = TRUE;
623 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
625 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
626 { /* client, wanting stapling */
627 /* Add the server cert's signing chain as the one
628 for the verification of the OCSP stapled information. */
630 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
633 sk_X509_push(client_static_cbinfo->verify_stack, cert);
636 #ifndef DISABLE_EVENT
637 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
638 return 0; /* reject, with peercert set */
643 const uschar * verify_cert_hostnames;
645 if ( tlsp == &tls_out
646 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
647 /* client, wanting hostname check */
650 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
651 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
652 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
654 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
655 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
658 const uschar * list = verify_cert_hostnames;
661 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
662 if ((rc = X509_check_host(cert, CCS name, 0,
663 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
664 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
669 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
670 tlsp == &tls_out ? deliver_host_address : sender_host_address);
677 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
680 uschar * extra = verify_mode
681 ? string_sprintf(" (during %c-verify for [%s])",
682 *verify_mode, sender_host_address)
684 log_write(0, LOG_MAIN,
685 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
686 tlsp == &tls_out ? deliver_host_address : sender_host_address,
687 extra, dn, verify_cert_hostnames);
692 tlsp->peercert = X509_dup(cert); /* record failing cert */
693 return 0; /* reject */
695 DEBUG(D_tls) debug_printf("SSL verify name failure overridden (host in "
696 "tls_try_verify_hosts)\n");
697 tlsp->verify_override = TRUE;
701 #ifndef DISABLE_EVENT
702 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
703 return 0; /* reject, with peercert set */
706 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
707 *calledp ? "" : " authenticated", dn);
711 return 1; /* accept, at least for this level */
715 verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
717 return verify_callback(preverify_ok, x509ctx, &tls_out,
718 &client_verify_callback_called, &client_verify_optional);
722 verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
724 return verify_callback(preverify_ok, x509ctx, &tls_in,
725 &server_verify_callback_called, &server_verify_optional);
731 /* This gets called *by* the dane library verify callback, which interposes
735 verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
737 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
739 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
740 #ifndef DISABLE_EVENT
741 BOOL dummy_called, optional = FALSE;
744 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
746 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
747 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
748 deliver_host_address);
751 dn[sizeof(dn)-1] = '\0';
753 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
754 preverify_ok ? "ok":"BAD", depth, dn);
756 #ifndef DISABLE_EVENT
757 if (verify_event(&tls_out, cert, depth, dn,
758 &dummy_called, &optional, US"DANE"))
759 return 0; /* reject, with peercert set */
762 if (preverify_ok == 1)
764 tls_out.dane_verified = TRUE;
766 if (client_static_cbinfo->u_ocsp.client.verify_store)
767 { /* client, wanting stapling */
768 /* Add the server cert's signing chain as the one
769 for the verification of the OCSP stapled information. */
771 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
774 sk_X509_push(client_static_cbinfo->verify_stack, cert);
780 int err = X509_STORE_CTX_get_error(x509ctx);
782 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
783 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
789 #endif /*SUPPORT_DANE*/
792 /*************************************************
793 * Information callback *
794 *************************************************/
796 /* The SSL library functions call this from time to time to indicate what they
797 are doing. We copy the string to the debugging output when TLS debugging has
809 info_callback(SSL *s, int where, int ret)
815 if (where & SSL_ST_CONNECT)
816 str = US"SSL_connect";
817 else if (where & SSL_ST_ACCEPT)
818 str = US"SSL_accept";
820 str = US"SSL info (undefined)";
822 if (where & SSL_CB_LOOP)
823 debug_printf("%s: %s\n", str, SSL_state_string_long(s));
824 else if (where & SSL_CB_ALERT)
825 debug_printf("SSL3 alert %s:%s:%s\n",
826 str = where & SSL_CB_READ ? US"read" : US"write",
827 SSL_alert_type_string_long(ret), SSL_alert_desc_string_long(ret));
828 else if (where & SSL_CB_EXIT)
830 debug_printf("%s: failed in %s\n", str, SSL_state_string_long(s));
832 debug_printf("%s: error in %s\n", str, SSL_state_string_long(s));
833 else if (where & SSL_CB_HANDSHAKE_START)
834 debug_printf("%s: hshake start: %s\n", str, SSL_state_string_long(s));
835 else if (where & SSL_CB_HANDSHAKE_DONE)
836 debug_printf("%s: hshake done: %s\n", str, SSL_state_string_long(s));
840 #ifdef OPENSSL_HAVE_KEYLOG_CB
842 keylog_callback(const SSL *ssl, const char *line)
846 DEBUG(D_tls) debug_printf("%.200s\n", line);
847 if (!(filename = getenv("SSLKEYLOGFILE"))) return;
848 if (!(fp = fopen(filename, "a"))) return;
849 fprintf(fp, "%s\n", line);
855 #ifdef EXPERIMENTAL_TLS_RESUME
856 /* Manage the keysets used for encrypting the session tickets, on the server. */
858 typedef struct { /* Session ticket encryption key */
861 const EVP_CIPHER * aes_cipher;
862 uschar aes_key[32]; /* size needed depends on cipher. aes_128 implies 128/8 = 16? */
863 const EVP_MD * hmac_hash;
869 static exim_stek exim_tk; /* current key */
870 static exim_stek exim_tk_old; /* previous key */
875 time_t t = time(NULL);
879 if (exim_tk.renew >= t) return;
880 exim_tk_old = exim_tk;
883 if (f.running_in_test_harness) ssl_session_timeout = 6;
885 DEBUG(D_tls) debug_printf("OpenSSL: %s STEK\n", exim_tk.name[0] ? "rotating" : "creating");
886 if (RAND_bytes(exim_tk.aes_key, sizeof(exim_tk.aes_key)) <= 0) return;
887 if (RAND_bytes(exim_tk.hmac_key, sizeof(exim_tk.hmac_key)) <= 0) return;
888 if (RAND_bytes(exim_tk.name+1, sizeof(exim_tk.name)-1) <= 0) return;
890 exim_tk.name[0] = 'E';
891 exim_tk.aes_cipher = EVP_aes_256_cbc();
892 exim_tk.hmac_hash = EVP_sha256();
893 exim_tk.expire = t + ssl_session_timeout;
894 exim_tk.renew = t + ssl_session_timeout/2;
900 if (!exim_tk.name[0]) return NULL;
905 tk_find(const uschar * name)
907 return memcmp(name, exim_tk.name, sizeof(exim_tk.name)) == 0 ? &exim_tk
908 : memcmp(name, exim_tk_old.name, sizeof(exim_tk_old.name)) == 0 ? &exim_tk_old
912 /* Callback for session tickets, on server */
914 ticket_key_callback(SSL * ssl, uschar key_name[16],
915 uschar * iv, EVP_CIPHER_CTX * ctx, HMAC_CTX * hctx, int enc)
917 tls_support * tlsp = server_static_cbinfo->tlsp;
922 DEBUG(D_tls) debug_printf("ticket_key_callback: create new session\n");
923 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
925 if (RAND_bytes(iv, EVP_MAX_IV_LENGTH) <= 0)
926 return -1; /* insufficient random */
928 if (!(key = tk_current())) /* current key doesn't exist or isn't valid */
929 return 0; /* key couldn't be created */
930 memcpy(key_name, key->name, 16);
931 DEBUG(D_tls) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - time(NULL));
933 /*XXX will want these dependent on the ssl session strength */
934 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
935 key->hmac_hash, NULL);
936 EVP_EncryptInit_ex(ctx, key->aes_cipher, NULL, key->aes_key, iv);
938 DEBUG(D_tls) debug_printf("ticket created\n");
943 time_t now = time(NULL);
945 DEBUG(D_tls) debug_printf("ticket_key_callback: retrieve session\n");
946 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
948 if (!(key = tk_find(key_name)) || key->expire < now)
952 debug_printf("ticket not usable (%s)\n", key ? "expired" : "not found");
953 if (key) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - now);
958 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
959 key->hmac_hash, NULL);
960 EVP_DecryptInit_ex(ctx, key->aes_cipher, NULL, key->aes_key, iv);
962 DEBUG(D_tls) debug_printf("ticket usable, STEK expire " TIME_T_FMT "\n", key->expire - now);
964 /* The ticket lifetime and renewal are the same as the STEK lifetime and
965 renewal, which is overenthusiastic. A factor of, say, 3x longer STEK would
966 be better. To do that we'd have to encode ticket lifetime in the name as
967 we don't yet see the restored session. Could check posthandshake for TLS1.3
968 and trigger a new ticket then, but cannot do that for TLS1.2 */
969 return key->renew < now ? 2 : 1;
976 /*************************************************
977 * Initialize for DH *
978 *************************************************/
980 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
983 sctx The current SSL CTX (inbound or outbound)
984 dhparam DH parameter file or fixed parameter identity string
985 host connected host, if client; NULL if server
986 errstr error string pointer
988 Returns: TRUE if OK (nothing to set up, or setup worked)
992 init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host, uschar ** errstr)
1000 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded, errstr))
1003 if (!dhexpanded || !*dhexpanded)
1004 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
1005 else if (dhexpanded[0] == '/')
1007 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
1009 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
1010 host, US strerror(errno), errstr);
1016 if (Ustrcmp(dhexpanded, "none") == 0)
1018 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
1022 if (!(pem = std_dh_prime_named(dhexpanded)))
1024 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
1025 host, US strerror(errno), errstr);
1028 bio = BIO_new_mem_buf(CS pem, -1);
1031 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
1034 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
1035 host, NULL, errstr);
1039 /* note: our default limit of 2236 is not a multiple of 8; the limit comes from
1040 * an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with
1041 * 2236. But older OpenSSL can only report in bytes (octets), not bits.
1042 * If someone wants to dance at the edge, then they can raise the limit or use
1043 * current libraries. */
1044 #ifdef EXIM_HAVE_OPENSSL_DH_BITS
1045 /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022
1046 * This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */
1047 dh_bitsize = DH_bits(dh);
1049 dh_bitsize = 8 * DH_size(dh);
1052 /* Even if it is larger, we silently return success rather than cause things
1053 * to fail out, so that a too-large DH will not knock out all TLS; it's a
1054 * debatable choice. */
1055 if (dh_bitsize > tls_dh_max_bits)
1058 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d\n",
1059 dh_bitsize, tls_dh_max_bits);
1063 SSL_CTX_set_tmp_dh(sctx, dh);
1065 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
1066 dhexpanded ? dhexpanded : US"default", dh_bitsize);
1078 /*************************************************
1079 * Initialize for ECDH *
1080 *************************************************/
1082 /* Load parameters for ECDH encryption.
1084 For now, we stick to NIST P-256 because: it's simple and easy to configure;
1085 it avoids any patent issues that might bite redistributors; despite events in
1086 the news and concerns over curve choices, we're not cryptographers, we're not
1087 pretending to be, and this is "good enough" to be better than no support,
1088 protecting against most adversaries. Given another year or two, there might
1089 be sufficient clarity about a "right" way forward to let us make an informed
1090 decision, instead of a knee-jerk reaction.
1092 Longer-term, we should look at supporting both various named curves and
1093 external files generated with "openssl ecparam", much as we do for init_dh().
1094 We should also support "none" as a value, to explicitly avoid initialisation.
1099 sctx The current SSL CTX (inbound or outbound)
1100 host connected host, if client; NULL if server
1101 errstr error string pointer
1103 Returns: TRUE if OK (nothing to set up, or setup worked)
1107 init_ecdh(SSL_CTX * sctx, host_item * host, uschar ** errstr)
1109 #ifdef OPENSSL_NO_ECDH
1118 if (host) /* No ECDH setup for clients, only for servers */
1121 # ifndef EXIM_HAVE_ECDH
1123 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
1127 if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve, errstr))
1129 if (!exp_curve || !*exp_curve)
1132 /* "auto" needs to be handled carefully.
1133 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
1134 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
1135 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
1136 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
1137 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
1139 if (Ustrcmp(exp_curve, "auto") == 0)
1141 #if OPENSSL_VERSION_NUMBER < 0x10002000L
1142 DEBUG(D_tls) debug_printf(
1143 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
1144 exp_curve = US"prime256v1";
1146 # if defined SSL_CTRL_SET_ECDH_AUTO
1147 DEBUG(D_tls) debug_printf(
1148 "ECDH OpenSSL 1.0.2+ temp key parameter settings: autoselection\n");
1149 SSL_CTX_set_ecdh_auto(sctx, 1);
1152 DEBUG(D_tls) debug_printf(
1153 "ECDH OpenSSL 1.1.0+ temp key parameter settings: default selection\n");
1159 DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve);
1160 if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef
1161 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
1162 && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef
1166 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve),
1167 host, NULL, errstr);
1171 if (!(ecdh = EC_KEY_new_by_curve_name(nid)))
1173 tls_error(US"Unable to create ec curve", host, NULL, errstr);
1177 /* The "tmp" in the name here refers to setting a temporary key
1178 not to the stability of the interface. */
1180 if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0))
1181 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), host, NULL, errstr);
1183 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve);
1188 # endif /*EXIM_HAVE_ECDH*/
1189 #endif /*OPENSSL_NO_ECDH*/
1195 #ifndef DISABLE_OCSP
1196 /*************************************************
1197 * Load OCSP information into state *
1198 *************************************************/
1199 /* Called to load the server OCSP response from the given file into memory, once
1200 caller has determined this is needed. Checks validity. Debugs a message
1203 ASSUMES: single response, for single cert.
1206 sctx the SSL_CTX* to update
1207 cbinfo various parts of session state
1208 filename the filename putatively holding an OCSP response
1213 ocsp_load_response(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo,
1214 const uschar * filename)
1217 OCSP_RESPONSE * resp;
1218 OCSP_BASICRESP * basic_response;
1219 OCSP_SINGLERESP * single_response;
1220 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
1221 STACK_OF(X509) * sk;
1222 unsigned long verify_flags;
1223 int status, reason, i;
1225 DEBUG(D_tls) debug_printf("tls_ocsp_file '%s'\n", filename);
1227 if (!(bio = BIO_new_file(CS filename, "rb")))
1229 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
1234 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
1238 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
1242 if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
1244 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
1245 OCSP_response_status_str(status), status);
1251 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1252 OCSP_RESPONSE_print(bp, resp, 0); /* extreme debug: stapling content */
1257 if (!(basic_response = OCSP_response_get1_basic(resp)))
1260 debug_printf("OCSP response parse error: unable to extract basic response.\n");
1264 sk = cbinfo->verify_stack;
1265 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
1267 /* May need to expose ability to adjust those flags?
1268 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
1269 OCSP_TRUSTOTHER OCSP_NOINTERN */
1271 /* This does a full verify on the OCSP proof before we load it for serving
1272 up; possibly overkill - just date-checks might be nice enough.
1274 OCSP_basic_verify takes a "store" arg, but does not
1275 use it for the chain verification, which is all we do
1276 when OCSP_NOVERIFY is set. The content from the wire
1277 "basic_response" and a cert-stack "sk" are all that is used.
1279 We have a stack, loaded in setup_certs() if tls_verify_certificates
1280 was a file (not a directory, or "system"). It is unfortunate we
1281 cannot used the connection context store, as that would neatly
1282 handle the "system" case too, but there seems to be no library
1283 function for getting a stack from a store.
1284 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
1285 We do not free the stack since it could be needed a second time for
1288 Separately we might try to replace using OCSP_basic_verify() - which seems to not
1289 be a public interface into the OpenSSL library (there's no manual entry) -
1290 But what with? We also use OCSP_basic_verify in the client stapling callback.
1291 And there we NEED it; we must verify that status... unless the
1292 library does it for us anyway? */
1294 if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0)
1298 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1299 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
1304 /* Here's the simplifying assumption: there's only one response, for the
1305 one certificate we use, and nothing for anything else in a chain. If this
1306 proves false, we need to extract a cert id from our issued cert
1307 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
1308 right cert in the stack and then calls OCSP_single_get0_status()).
1310 I'm hoping to avoid reworking a bunch more of how we handle state here.
1312 XXX that will change when we add support for (TLS1.3) whole-chain stapling
1315 if (!(single_response = OCSP_resp_get0(basic_response, 0)))
1318 debug_printf("Unable to get first response from OCSP basic response.\n");
1322 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
1323 if (status != V_OCSP_CERTSTATUS_GOOD)
1325 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
1326 OCSP_cert_status_str(status), status,
1327 OCSP_crl_reason_str(reason), reason);
1331 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1333 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
1338 /* Add the resp to the list used by tls_server_stapling_cb() */
1340 ocsp_resplist ** op = &cbinfo->u_ocsp.server.olist, * oentry;
1341 while (oentry = *op)
1343 *op = oentry = store_get(sizeof(ocsp_resplist), FALSE);
1344 oentry->next = NULL;
1345 oentry->resp = resp;
1350 if (f.running_in_test_harness)
1352 extern char ** environ;
1353 if (environ) for (uschar ** p = USS environ; *p; p++)
1354 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1356 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
1357 goto supply_response;
1365 ocsp_free_response_list(tls_ext_ctx_cb * cbinfo)
1367 for (ocsp_resplist * olist = cbinfo->u_ocsp.server.olist; olist;
1368 olist = olist->next)
1369 OCSP_RESPONSE_free(olist->resp);
1370 cbinfo->u_ocsp.server.olist = NULL;
1372 #endif /*!DISABLE_OCSP*/
1377 /* Create and install a selfsigned certificate, for use in server mode */
1380 tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr)
1388 where = US"allocating pkey";
1389 if (!(pkey = EVP_PKEY_new()))
1392 where = US"allocating cert";
1393 if (!(x509 = X509_new()))
1396 where = US"generating pkey";
1397 if (!(rsa = rsa_callback(NULL, 0, 2048)))
1400 where = US"assigning pkey";
1401 if (!EVP_PKEY_assign_RSA(pkey, rsa))
1404 X509_set_version(x509, 2); /* N+1 - version 3 */
1405 ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
1406 X509_gmtime_adj(X509_get_notBefore(x509), 0);
1407 X509_gmtime_adj(X509_get_notAfter(x509), (long)60 * 60); /* 1 hour */
1408 X509_set_pubkey(x509, pkey);
1410 name = X509_get_subject_name(x509);
1411 X509_NAME_add_entry_by_txt(name, "C",
1412 MBSTRING_ASC, CUS "UK", -1, -1, 0);
1413 X509_NAME_add_entry_by_txt(name, "O",
1414 MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0);
1415 X509_NAME_add_entry_by_txt(name, "CN",
1416 MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0);
1417 X509_set_issuer_name(x509, name);
1419 where = US"signing cert";
1420 if (!X509_sign(x509, pkey, EVP_md5()))
1423 where = US"installing selfsign cert";
1424 if (!SSL_CTX_use_certificate(sctx, x509))
1427 where = US"installing selfsign key";
1428 if (!SSL_CTX_use_PrivateKey(sctx, pkey))
1434 (void) tls_error(where, NULL, NULL, errstr);
1435 if (x509) X509_free(x509);
1436 if (pkey) EVP_PKEY_free(pkey);
1444 tls_add_certfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file,
1447 DEBUG(D_tls) debug_printf("tls_certificate file '%s'\n", file);
1448 if (!SSL_CTX_use_certificate_chain_file(sctx, CS file))
1449 return tls_error(string_sprintf(
1450 "SSL_CTX_use_certificate_chain_file file=%s", file),
1451 cbinfo->host, NULL, errstr);
1456 tls_add_pkeyfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file,
1459 DEBUG(D_tls) debug_printf("tls_privatekey file '%s'\n", file);
1460 if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM))
1461 return tls_error(string_sprintf(
1462 "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr);
1467 /*************************************************
1468 * Expand key and cert file specs *
1469 *************************************************/
1471 /* Called once during tls_init and possibly again during TLS setup, for a
1472 new context, if Server Name Indication was used and tls_sni was seen in
1473 the certificate string.
1476 sctx the SSL_CTX* to update
1477 cbinfo various parts of session state
1478 errstr error string pointer
1480 Returns: OK/DEFER/FAIL
1484 tls_expand_session_files(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo,
1489 if (!cbinfo->certificate)
1491 if (!cbinfo->is_server) /* client */
1494 if (tls_install_selfsign(sctx, errstr) != OK)
1501 if ( !reexpand_tls_files_for_sni
1502 && ( Ustrstr(cbinfo->certificate, US"tls_sni")
1503 || Ustrstr(cbinfo->certificate, US"tls_in_sni")
1504 || Ustrstr(cbinfo->certificate, US"tls_out_sni")
1506 reexpand_tls_files_for_sni = TRUE;
1508 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded, errstr))
1512 if (cbinfo->is_server)
1514 const uschar * file_list = expanded;
1517 #ifndef DISABLE_OCSP
1518 const uschar * olist = cbinfo->u_ocsp.server.file;
1523 if (!expand_check(olist, US"tls_ocsp_file", USS &olist, errstr))
1525 if (olist && !*olist)
1528 if ( cbinfo->u_ocsp.server.file_expanded && olist
1529 && (Ustrcmp(olist, cbinfo->u_ocsp.server.file_expanded) == 0))
1531 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
1536 ocsp_free_response_list(cbinfo);
1537 cbinfo->u_ocsp.server.file_expanded = olist;
1541 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1543 if ((err = tls_add_certfile(sctx, cbinfo, file, errstr)))
1546 #ifndef DISABLE_OCSP
1548 if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1549 ocsp_load_response(sctx, cbinfo, ofile);
1551 DEBUG(D_tls) debug_printf("ran out of ocsp file list\n");
1555 else /* would there ever be a need for multiple client certs? */
1556 if ((err = tls_add_certfile(sctx, cbinfo, expanded, errstr)))
1559 if ( cbinfo->privatekey
1560 && !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded, errstr))
1563 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1564 of the expansion is an empty string, ignore it also, and assume the private
1565 key is in the same file as the certificate. */
1567 if (expanded && *expanded)
1568 if (cbinfo->is_server)
1570 const uschar * file_list = expanded;
1574 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1575 if ((err = tls_add_pkeyfile(sctx, cbinfo, file, errstr)))
1578 else /* would there ever be a need for multiple client certs? */
1579 if ((err = tls_add_pkeyfile(sctx, cbinfo, expanded, errstr)))
1589 /*************************************************
1590 * Callback to handle SNI *
1591 *************************************************/
1593 /* Called when acting as server during the TLS session setup if a Server Name
1594 Indication extension was sent by the client.
1596 API documentation is OpenSSL s_server.c implementation.
1599 s SSL* of the current session
1600 ad unknown (part of OpenSSL API) (unused)
1601 arg Callback of "our" registered data
1603 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
1605 XXX might need to change to using ClientHello callback,
1606 per https://www.openssl.org/docs/manmaster/man3/SSL_client_hello_cb_fn.html
1609 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1611 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
1613 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
1614 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
1616 int old_pool = store_pool;
1617 uschar * dummy_errstr;
1620 return SSL_TLSEXT_ERR_OK;
1622 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
1623 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
1625 /* Make the extension value available for expansion */
1626 store_pool = POOL_PERM;
1627 tls_in.sni = string_copy_taint(US servername, TRUE);
1628 store_pool = old_pool;
1630 if (!reexpand_tls_files_for_sni)
1631 return SSL_TLSEXT_ERR_OK;
1633 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
1634 not confident that memcpy wouldn't break some internal reference counting.
1635 Especially since there's a references struct member, which would be off. */
1637 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1638 if (!(server_sni = SSL_CTX_new(TLS_server_method())))
1640 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
1643 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1644 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
1648 /* Not sure how many of these are actually needed, since SSL object
1649 already exists. Might even need this selfsame callback, for reneg? */
1651 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
1652 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
1653 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
1654 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
1655 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
1656 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
1658 if ( !init_dh(server_sni, cbinfo->dhparam, NULL, &dummy_errstr)
1659 || !init_ecdh(server_sni, NULL, &dummy_errstr)
1663 if ( cbinfo->server_cipher_list
1664 && !SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list))
1667 #ifndef DISABLE_OCSP
1668 if (cbinfo->u_ocsp.server.file)
1670 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
1671 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
1675 if ((rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE,
1676 verify_callback_server, &dummy_errstr)) != OK)
1679 /* do this after setup_certs, because this can require the certs for verifying
1680 OCSP information. */
1681 if ((rc = tls_expand_session_files(server_sni, cbinfo, &dummy_errstr)) != OK)
1684 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
1685 SSL_set_SSL_CTX(s, server_sni);
1686 return SSL_TLSEXT_ERR_OK;
1688 bad: return SSL_TLSEXT_ERR_ALERT_FATAL;
1690 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
1695 #ifndef DISABLE_OCSP
1697 /*************************************************
1698 * Callback to handle OCSP Stapling *
1699 *************************************************/
1701 /* Called when acting as server during the TLS session setup if the client
1702 requests OCSP information with a Certificate Status Request.
1704 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
1710 tls_server_stapling_cb(SSL *s, void *arg)
1712 const tls_ext_ctx_cb * cbinfo = (tls_ext_ctx_cb *) arg;
1713 ocsp_resplist * olist = cbinfo->u_ocsp.server.olist;
1714 uschar * response_der; /*XXX blob */
1715 int response_der_len;
1718 debug_printf("Received TLS status request (OCSP stapling); %s response list\n",
1719 olist ? "have" : "lack");
1721 tls_in.ocsp = OCSP_NOT_RESP;
1723 return SSL_TLSEXT_ERR_NOACK;
1725 #ifdef EXIM_HAVE_OPESSL_GET0_SERIAL
1727 const X509 * cert_sent = SSL_get_certificate(s);
1728 const ASN1_INTEGER * cert_serial = X509_get0_serialNumber(cert_sent);
1729 const BIGNUM * cert_bn = ASN1_INTEGER_to_BN(cert_serial, NULL);
1730 const X509_NAME * cert_issuer = X509_get_issuer_name(cert_sent);
1734 for (; olist; olist = olist->next)
1736 OCSP_BASICRESP * bs = OCSP_response_get1_basic(olist->resp);
1737 const OCSP_SINGLERESP * single = OCSP_resp_get0(bs, 0);
1738 const OCSP_CERTID * cid = OCSP_SINGLERESP_get0_id(single);
1739 ASN1_INTEGER * res_cert_serial;
1740 const BIGNUM * resp_bn;
1741 ASN1_OCTET_STRING * res_cert_iNameHash;
1744 (void) OCSP_id_get0_info(&res_cert_iNameHash, NULL, NULL, &res_cert_serial,
1745 (OCSP_CERTID *) cid);
1746 resp_bn = ASN1_INTEGER_to_BN(res_cert_serial, NULL);
1750 debug_printf("cert serial: %s\n", BN_bn2hex(cert_bn));
1751 debug_printf("resp serial: %s\n", BN_bn2hex(resp_bn));
1754 if (BN_cmp(cert_bn, resp_bn) == 0)
1756 DEBUG(D_tls) debug_printf("matched serial for ocsp\n");
1758 /*XXX TODO: check the rest of the list for duplicate matches.
1759 If any, need to also check the Issuer Name hash.
1760 Without this, we will provide the wrong status in the case of
1765 DEBUG(D_tls) debug_printf("not match serial for ocsp\n");
1769 DEBUG(D_tls) debug_printf("failed to find match for ocsp\n");
1770 return SSL_TLSEXT_ERR_NOACK;
1776 DEBUG(D_tls) debug_printf("OpenSSL version too early to support multi-leaf OCSP\n");
1777 return SSL_TLSEXT_ERR_NOACK;
1781 /*XXX could we do the i2d earlier, rather than during the callback? */
1782 response_der = NULL;
1783 response_der_len = i2d_OCSP_RESPONSE(olist->resp, &response_der);
1784 if (response_der_len <= 0)
1785 return SSL_TLSEXT_ERR_NOACK;
1787 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
1788 tls_in.ocsp = OCSP_VFIED;
1789 return SSL_TLSEXT_ERR_OK;
1794 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
1796 BIO_printf(bp, "\t%s: ", str);
1797 ASN1_GENERALIZEDTIME_print(bp, time);
1802 tls_client_stapling_cb(SSL *s, void *arg)
1804 tls_ext_ctx_cb * cbinfo = arg;
1805 const unsigned char * p;
1807 OCSP_RESPONSE * rsp;
1808 OCSP_BASICRESP * bs;
1811 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
1812 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
1815 /* Expect this when we requested ocsp but got none */
1816 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
1817 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
1819 DEBUG(D_tls) debug_printf(" null\n");
1820 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1823 if (!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
1825 tls_out.ocsp = OCSP_FAILED; /*XXX should use tlsp-> to permit concurrent outbound */
1826 if (LOGGING(tls_cipher))
1827 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
1829 DEBUG(D_tls) debug_printf(" parse error\n");
1833 if (!(bs = OCSP_response_get1_basic(rsp)))
1835 tls_out.ocsp = OCSP_FAILED;
1836 if (LOGGING(tls_cipher))
1837 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
1839 DEBUG(D_tls) debug_printf(" error parsing response\n");
1840 OCSP_RESPONSE_free(rsp);
1844 /* We'd check the nonce here if we'd put one in the request. */
1845 /* However that would defeat cacheability on the server so we don't. */
1847 /* This section of code reworked from OpenSSL apps source;
1848 The OpenSSL Project retains copyright:
1849 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1854 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1856 DEBUG(D_tls) bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1858 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1860 /* Use the chain that verified the server cert to verify the stapled info */
1861 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1863 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
1864 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
1866 tls_out.ocsp = OCSP_FAILED;
1867 if (LOGGING(tls_cipher)) log_write(0, LOG_MAIN,
1868 "Received TLS cert status response, itself unverifiable: %s",
1869 ERR_reason_error_string(ERR_peek_error()));
1870 BIO_printf(bp, "OCSP response verify failure\n");
1871 ERR_print_errors(bp);
1872 OCSP_RESPONSE_print(bp, rsp, 0);
1876 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1878 /*XXX So we have a good stapled OCSP status. How do we know
1879 it is for the cert of interest? OpenSSL 1.1.0 has a routine
1880 OCSP_resp_find_status() which matches on a cert id, which presumably
1881 we should use. Making an id needs OCSP_cert_id_new(), which takes
1882 issuerName, issuerKey, serialNumber. Are they all in the cert?
1884 For now, carry on blindly accepting the resp. */
1887 OCSP_SINGLERESP * single;
1889 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
1890 if (OCSP_resp_count(bs) != 1)
1892 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1893 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1896 tls_out.ocsp = OCSP_FAILED;
1897 log_write(0, LOG_MAIN, "OCSP stapling "
1898 "with multiple responses not handled");
1901 single = OCSP_resp_get0(bs, 0);
1902 status = OCSP_single_get0_status(single, &reason, &rev,
1903 &thisupd, &nextupd);
1906 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1907 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1908 if (!OCSP_check_validity(thisupd, nextupd,
1909 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1911 tls_out.ocsp = OCSP_FAILED;
1912 DEBUG(D_tls) ERR_print_errors(bp);
1913 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1917 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1918 OCSP_cert_status_str(status));
1921 case V_OCSP_CERTSTATUS_GOOD:
1922 tls_out.ocsp = OCSP_VFIED;
1925 case V_OCSP_CERTSTATUS_REVOKED:
1926 tls_out.ocsp = OCSP_FAILED;
1927 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1928 reason != -1 ? "; reason: " : "",
1929 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1930 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1933 tls_out.ocsp = OCSP_FAILED;
1934 log_write(0, LOG_MAIN,
1935 "Server certificate status unknown, in OCSP stapling");
1940 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1945 OCSP_RESPONSE_free(rsp);
1948 #endif /*!DISABLE_OCSP*/
1951 /*************************************************
1952 * Initialize for TLS *
1953 *************************************************/
1956 tls_openssl_init(void)
1958 #ifdef EXIM_NEED_OPENSSL_INIT
1959 SSL_load_error_strings(); /* basic set up */
1960 OpenSSL_add_ssl_algorithms();
1963 #if defined(EXIM_HAVE_SHA256) && !defined(OPENSSL_AUTO_SHA256)
1964 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1965 list of available digests. */
1966 EVP_add_digest(EVP_sha256());
1972 /* Called from both server and client code, to do preliminary initialization
1973 of the library. We allocate and return a context structure.
1976 ctxp returned SSL context
1977 host connected host, if client; NULL if server
1978 dhparam DH parameter file
1979 certificate certificate file
1980 privatekey private key
1981 ocsp_file file of stapling info (server); flag for require ocsp (client)
1982 addr address if client; NULL if server (for some randomness)
1983 cbp place to put allocated callback context
1984 errstr error string pointer
1986 Returns: OK/DEFER/FAIL
1990 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1992 #ifndef DISABLE_OCSP
1995 address_item *addr, tls_ext_ctx_cb ** cbp,
2002 tls_ext_ctx_cb * cbinfo;
2004 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
2005 cbinfo->tlsp = tlsp;
2006 cbinfo->certificate = certificate;
2007 cbinfo->privatekey = privatekey;
2008 cbinfo->is_server = host==NULL;
2009 #ifndef DISABLE_OCSP
2010 cbinfo->verify_stack = NULL;
2013 cbinfo->u_ocsp.server.file = ocsp_file;
2014 cbinfo->u_ocsp.server.file_expanded = NULL;
2015 cbinfo->u_ocsp.server.olist = NULL;
2018 cbinfo->u_ocsp.client.verify_store = NULL;
2020 cbinfo->dhparam = dhparam;
2021 cbinfo->server_cipher_list = NULL;
2022 cbinfo->host = host;
2023 #ifndef DISABLE_EVENT
2024 cbinfo->event_action = NULL;
2029 /* Create a context.
2030 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
2031 negotiation in the different methods; as far as I can tell, the only
2032 *_{server,client}_method which allows negotiation is SSLv23, which exists even
2033 when OpenSSL is built without SSLv2 support.
2034 By disabling with openssl_options, we can let admins re-enable with the
2037 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
2038 if (!(ctx = SSL_CTX_new(host ? TLS_client_method() : TLS_server_method())))
2040 if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
2042 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
2044 /* It turns out that we need to seed the random number generator this early in
2045 order to get the full complement of ciphers to work. It took me roughly a day
2046 of work to discover this by experiment.
2048 On systems that have /dev/urandom, SSL may automatically seed itself from
2049 there. Otherwise, we have to make something up as best we can. Double check
2055 gettimeofday(&r.tv, NULL);
2058 RAND_seed(US (&r), sizeof(r));
2059 RAND_seed(US big_buffer, big_buffer_size);
2060 if (addr != NULL) RAND_seed(US addr, sizeof(addr));
2063 return tls_error(US"RAND_status", host,
2064 US"unable to seed random number generator", errstr);
2067 /* Set up the information callback, which outputs if debugging is at a suitable
2072 SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
2073 #if defined(EXIM_HAVE_OPESSL_TRACE) && !defined(OPENSSL_NO_SSL_TRACE)
2074 /* this needs a debug build of OpenSSL */
2075 SSL_CTX_set_msg_callback(ctx, (void (*)())SSL_trace);
2077 #ifdef OPENSSL_HAVE_KEYLOG_CB
2078 SSL_CTX_set_keylog_callback(ctx, (void (*)())keylog_callback);
2082 /* Automatically re-try reads/writes after renegotiation. */
2083 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
2085 /* Apply administrator-supplied work-arounds.
2086 Historically we applied just one requested option,
2087 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
2088 moved to an administrator-controlled list of options to specify and
2089 grandfathered in the first one as the default value for "openssl_options".
2091 No OpenSSL version number checks: the options we accept depend upon the
2092 availability of the option value macros from OpenSSL. */
2094 if (!tls_openssl_options_parse(openssl_options, &init_options))
2095 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
2097 #ifdef EXPERIMENTAL_TLS_RESUME
2098 tlsp->resumption = RESUME_SUPPORTED;
2102 #ifdef EXPERIMENTAL_TLS_RESUME
2103 /* Should the server offer session resumption? */
2104 if (!host && verify_check_host(&tls_resumption_hosts) == OK)
2106 DEBUG(D_tls) debug_printf("tls_resumption_hosts overrides openssl_options\n");
2107 init_options &= ~SSL_OP_NO_TICKET;
2108 tlsp->resumption |= RESUME_SERVER_TICKET; /* server will give ticket on request */
2109 tlsp->host_resumable = TRUE;
2113 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
2114 if (!(SSL_CTX_set_options(ctx, init_options)))
2115 return tls_error(string_sprintf(
2116 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
2119 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
2121 /* We'd like to disable session cache unconditionally, but foolish Outlook
2122 Express clients then give up the first TLS connection and make a second one
2123 (which works). Only when there is an IMAP service on the same machine.
2124 Presumably OE is trying to use the cache for A on B. Leave it enabled for
2125 now, until we work out a decent way of presenting control to the config. It
2126 will never be used because we use a new context every time. */
2128 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
2131 /* Initialize with DH parameters if supplied */
2132 /* Initialize ECDH temp key parameter selection */
2134 if ( !init_dh(ctx, dhparam, host, errstr)
2135 || !init_ecdh(ctx, host, errstr)
2139 /* Set up certificate and key (and perhaps OCSP info) */
2141 if ((rc = tls_expand_session_files(ctx, cbinfo, errstr)) != OK)
2144 /* If we need to handle SNI or OCSP, do so */
2146 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2147 # ifndef DISABLE_OCSP
2148 if (!(cbinfo->verify_stack = sk_X509_new_null()))
2150 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
2155 if (!host) /* server */
2157 # ifndef DISABLE_OCSP
2158 /* We check u_ocsp.server.file, not server.olist, because we care about if
2159 the option exists, not what the current expansion might be, as SNI might
2160 change the certificate and OCSP file in use between now and the time the
2161 callback is invoked. */
2162 if (cbinfo->u_ocsp.server.file)
2164 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
2165 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
2168 /* We always do this, so that $tls_sni is available even if not used in
2170 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
2171 SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo);
2173 # ifndef DISABLE_OCSP
2175 if(ocsp_file) /* wanting stapling */
2177 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
2179 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
2182 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
2183 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
2188 cbinfo->verify_cert_hostnames = NULL;
2190 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
2191 /* Set up the RSA callback */
2192 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
2195 /* Finally, set the session cache timeout, and we are done.
2196 The period appears to be also used for (server-generated) session tickets */
2198 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
2199 DEBUG(D_tls) debug_printf("Initialized TLS\n");
2210 /*************************************************
2211 * Get name of cipher in use *
2212 *************************************************/
2215 Argument: pointer to an SSL structure for the connection
2216 pointer to number of bits for cipher
2217 Returns: pointer to allocated string in perm-pool
2221 construct_cipher_name(SSL * ssl, int * bits)
2223 int pool = store_pool;
2224 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
2225 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
2226 the accessor functions use const in the prototype. */
2228 const uschar * ver = CUS SSL_get_version(ssl);
2229 const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
2232 SSL_CIPHER_get_bits(c, bits);
2234 store_pool = POOL_PERM;
2235 s = string_sprintf("%s:%s:%u", ver, SSL_CIPHER_get_name(c), *bits);
2237 DEBUG(D_tls) debug_printf("Cipher: %s\n", s);
2242 /* Get IETF-standard name for ciphersuite.
2243 Argument: pointer to an SSL structure for the connection
2244 Returns: pointer to string
2247 static const uschar *
2248 cipher_stdname_ssl(SSL * ssl)
2250 #ifdef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
2251 return CUS SSL_CIPHER_standard_name(SSL_get_current_cipher(ssl));
2253 ushort id = 0xffff & SSL_CIPHER_get_id(SSL_get_current_cipher(ssl));
2254 return cipher_stdname(id >> 8, id & 0xff);
2260 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned siz)
2262 /*XXX we might consider a list-of-certs variable for the cert chain.
2263 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
2264 in list-handling functions, also consider the difference between the entire
2265 chain and the elements sent by the peer. */
2267 tlsp->peerdn = NULL;
2269 /* Will have already noted peercert on a verify fail; possibly not the leaf */
2270 if (!tlsp->peercert)
2271 tlsp->peercert = SSL_get_peer_certificate(ssl);
2272 /* Beware anonymous ciphers which lead to server_cert being NULL */
2274 if (!X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, siz))
2275 { DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n"); }
2278 int oldpool = store_pool;
2280 peerdn[siz-1] = '\0'; /* paranoia */
2281 store_pool = POOL_PERM;
2282 tlsp->peerdn = string_copy(peerdn);
2283 store_pool = oldpool;
2285 /* We used to set CV in the cert-verify callbacks (either plain or dane)
2286 but they don't get called on session-resumption. So use the official
2287 interface, which uses the resumed value. Unfortunately this claims verified
2288 when it actually failed but we're in try-verify mode, due to us wanting the
2289 knowlege that it failed so needing to have the callback and forcing a
2290 permissive return. If we don't force it, the TLS startup is failed.
2291 The extra bit of information is set in verify_override in the cb, stashed
2292 for resumption next to the TLS session, and used here. */
2294 if (!tlsp->verify_override)
2295 tlsp->certificate_verified = SSL_get_verify_result(ssl) == X509_V_OK;
2303 /*************************************************
2304 * Set up for verifying certificates *
2305 *************************************************/
2307 #ifndef DISABLE_OCSP
2308 /* Load certs from file, return TRUE on success */
2311 chain_from_pem_file(const uschar * file, STACK_OF(X509) * verify_stack)
2316 while (sk_X509_num(verify_stack) > 0)
2317 X509_free(sk_X509_pop(verify_stack));
2319 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
2320 while ((x = PEM_read_bio_X509(bp, NULL, 0, NULL)))
2321 sk_X509_push(verify_stack, x);
2329 /* Called by both client and server startup; on the server possibly
2330 repeated after a Server Name Indication.
2333 sctx SSL_CTX* to initialise
2334 certs certs file or NULL
2335 crl CRL file or NULL
2336 host NULL in a server; the remote host in a client
2337 optional TRUE if called from a server for a host in tls_try_verify_hosts;
2338 otherwise passed as FALSE
2339 cert_vfy_cb Callback function for certificate verification
2340 errstr error string pointer
2342 Returns: OK/DEFER/FAIL
2346 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
2347 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr)
2349 uschar *expcerts, *expcrl;
2351 if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
2353 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
2355 if (expcerts && *expcerts)
2357 /* Tell the library to use its compiled-in location for the system default
2358 CA bundle. Then add the ones specified in the config, if any. */
2360 if (!SSL_CTX_set_default_verify_paths(sctx))
2361 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
2363 if (Ustrcmp(expcerts, "system") != 0)
2365 struct stat statbuf;
2367 if (Ustat(expcerts, &statbuf) < 0)
2369 log_write(0, LOG_MAIN|LOG_PANIC,
2370 "failed to stat %s for certificates", expcerts);
2376 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
2377 { file = NULL; dir = expcerts; }
2380 file = expcerts; dir = NULL;
2381 #ifndef DISABLE_OCSP
2382 /* In the server if we will be offering an OCSP proof, load chain from
2383 file for verifying the OCSP proof at load time. */
2385 /*XXX Glitch! The file here is tls_verify_certs: the chain for verifying the client cert.
2386 This is inconsistent with the need to verify the OCSP proof of the server cert.
2390 && statbuf.st_size > 0
2391 && server_static_cbinfo->u_ocsp.server.file
2392 && !chain_from_pem_file(file, server_static_cbinfo->verify_stack)
2395 log_write(0, LOG_MAIN|LOG_PANIC,
2396 "failed to load cert chain from %s", file);
2402 /* If a certificate file is empty, the next function fails with an
2403 unhelpful error message. If we skip it, we get the correct behaviour (no
2404 certificates are recognized, but the error message is still misleading (it
2405 says no certificate was supplied). But this is better. */
2407 if ( (!file || statbuf.st_size > 0)
2408 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
2409 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL, errstr);
2411 /* Load the list of CAs for which we will accept certs, for sending
2412 to the client. This is only for the one-file tls_verify_certificates
2414 If a list isn't loaded into the server, but some verify locations are set,
2415 the server end appears to make a wildcard request for client certs.
2416 Meanwhile, the client library as default behaviour *ignores* the list
2417 we send over the wire - see man SSL_CTX_set_client_cert_cb.
2418 Because of this, and that the dir variant is likely only used for
2419 the public-CA bundle (not for a private CA), not worth fixing. */
2423 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
2425 SSL_CTX_set_client_CA_list(sctx, names);
2426 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
2427 sk_X509_NAME_num(names));
2432 /* Handle a certificate revocation list. */
2434 #if OPENSSL_VERSION_NUMBER > 0x00907000L
2436 /* This bit of code is now the version supplied by Lars Mainka. (I have
2437 merely reformatted it into the Exim code style.)
2439 "From here I changed the code to add support for multiple crl's
2440 in pem format in one file or to support hashed directory entries in
2441 pem format instead of a file. This method now uses the library function
2442 X509_STORE_load_locations to add the CRL location to the SSL context.
2443 OpenSSL will then handle the verify against CA certs and CRLs by
2444 itself in the verify callback." */
2446 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
2447 if (expcrl && *expcrl)
2449 struct stat statbufcrl;
2450 if (Ustat(expcrl, &statbufcrl) < 0)
2452 log_write(0, LOG_MAIN|LOG_PANIC,
2453 "failed to stat %s for certificates revocation lists", expcrl);
2458 /* is it a file or directory? */
2460 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
2461 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
2465 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
2471 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
2473 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
2474 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
2476 /* setting the flags to check against the complete crl chain */
2478 X509_STORE_set_flags(cvstore,
2479 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
2483 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
2485 /* If verification is optional, don't fail if no certificate */
2487 SSL_CTX_set_verify(sctx,
2488 SSL_VERIFY_PEER | (optional ? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
2497 /*************************************************
2498 * Start a TLS session in a server *
2499 *************************************************/
2501 /* This is called when Exim is running as a server, after having received
2502 the STARTTLS command. It must respond to that command, and then negotiate
2506 require_ciphers allowed ciphers
2507 errstr pointer to error message
2509 Returns: OK on success
2510 DEFER for errors before the start of the negotiation
2511 FAIL for errors during the negotiation; the server can't
2516 tls_server_start(const uschar * require_ciphers, uschar ** errstr)
2519 uschar * expciphers;
2520 tls_ext_ctx_cb * cbinfo;
2521 static uschar peerdn[256];
2523 /* Check for previous activation */
2525 if (tls_in.active.sock >= 0)
2527 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
2528 smtp_printf("554 Already in TLS\r\n", FALSE);
2532 /* Initialize the SSL library. If it fails, it will already have logged
2535 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
2536 #ifndef DISABLE_OCSP
2539 NULL, &server_static_cbinfo, &tls_in, errstr);
2540 if (rc != OK) return rc;
2541 cbinfo = server_static_cbinfo;
2543 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
2546 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2547 were historically separated by underscores. So that I can use either form in my
2548 tests, and also for general convenience, we turn underscores into hyphens here.
2550 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
2551 for TLS 1.3 . Since we do not call it at present we get the default list:
2552 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
2557 for (uschar * s = expciphers; *s; s++ ) if (*s == '_') *s = '-';
2558 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
2559 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
2560 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
2561 cbinfo->server_cipher_list = expciphers;
2564 /* If this is a host for which certificate verification is mandatory or
2565 optional, set up appropriately. */
2567 tls_in.certificate_verified = FALSE;
2569 tls_in.dane_verified = FALSE;
2571 server_verify_callback_called = FALSE;
2573 if (verify_check_host(&tls_verify_hosts) == OK)
2575 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
2576 FALSE, verify_callback_server, errstr);
2577 if (rc != OK) return rc;
2578 server_verify_optional = FALSE;
2580 else if (verify_check_host(&tls_try_verify_hosts) == OK)
2582 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
2583 TRUE, verify_callback_server, errstr);
2584 if (rc != OK) return rc;
2585 server_verify_optional = TRUE;
2588 #ifdef EXPERIMENTAL_TLS_RESUME
2589 SSL_CTX_set_tlsext_ticket_key_cb(server_ctx, ticket_key_callback);
2590 /* despite working, appears to always return failure, so ignoring */
2592 #ifdef OPENSSL_HAVE_NUM_TICKETS
2593 # ifdef EXPERIMENTAL_TLS_RESUME
2594 SSL_CTX_set_num_tickets(server_ctx, tls_in.host_resumable ? 1 : 0);
2596 SSL_CTX_set_num_tickets(server_ctx, 0); /* send no TLS1.3 stateful-tickets */
2601 /* Prepare for new connection */
2603 if (!(server_ssl = SSL_new(server_ctx)))
2604 return tls_error(US"SSL_new", NULL, NULL, errstr);
2606 /* Warning: we used to SSL_clear(ssl) here, it was removed.
2608 * With the SSL_clear(), we get strange interoperability bugs with
2609 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
2610 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
2612 * The SSL_clear() call is to let an existing SSL* be reused, typically after
2613 * session shutdown. In this case, we have a brand new object and there's no
2614 * obvious reason to immediately clear it. I'm guessing that this was
2615 * originally added because of incomplete initialisation which the clear fixed,
2616 * in some historic release.
2619 /* Set context and tell client to go ahead, except in the case of TLS startup
2620 on connection, where outputting anything now upsets the clients and tends to
2621 make them disconnect. We need to have an explicit fflush() here, to force out
2622 the response. Other smtp_printf() calls do not need it, because in non-TLS
2623 mode, the fflush() happens when smtp_getc() is called. */
2625 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
2626 if (!tls_in.on_connect)
2628 smtp_printf("220 TLS go ahead\r\n", FALSE);
2632 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2633 that the OpenSSL library doesn't. */
2635 SSL_set_wfd(server_ssl, fileno(smtp_out));
2636 SSL_set_rfd(server_ssl, fileno(smtp_in));
2637 SSL_set_accept_state(server_ssl);
2639 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
2641 sigalrm_seen = FALSE;
2642 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
2643 rc = SSL_accept(server_ssl);
2648 int error = SSL_get_error(server_ssl, rc);
2651 case SSL_ERROR_NONE:
2654 case SSL_ERROR_ZERO_RETURN:
2655 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2656 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
2658 if (SSL_get_shutdown(server_ssl) == SSL_RECEIVED_SHUTDOWN)
2659 SSL_shutdown(server_ssl);
2661 tls_close(NULL, TLS_NO_SHUTDOWN);
2664 /* Handle genuine errors */
2666 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
2670 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2671 if (error == SSL_ERROR_SYSCALL)
2675 *errstr = US"SSL_accept: TCP connection closed by peer";
2678 DEBUG(D_tls) debug_printf(" - syscall %s\n", strerror(errno));
2680 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
2685 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
2686 ERR_clear_error(); /* Even success can leave errors in the stack. Seen with
2687 anon-authentication ciphersuite negotiated. */
2689 #ifdef EXPERIMENTAL_TLS_RESUME
2690 if (SSL_session_reused(server_ssl))
2692 tls_in.resumption |= RESUME_USED;
2693 DEBUG(D_tls) debug_printf("Session reused\n");
2697 /* TLS has been set up. Adjust the input functions to read via TLS,
2698 and initialize things. */
2700 peer_cert(server_ssl, &tls_in, peerdn, sizeof(peerdn));
2702 tls_in.cipher = construct_cipher_name(server_ssl, &tls_in.bits);
2703 tls_in.cipher_stdname = cipher_stdname_ssl(server_ssl);
2708 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)))
2709 debug_printf("Shared ciphers: %s\n", buf);
2711 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
2713 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
2714 SSL_SESSION_print_keylog(bp, SSL_get_session(server_ssl));
2719 #ifdef EXIM_HAVE_SESSION_TICKET
2721 SSL_SESSION * ss = SSL_get_session(server_ssl);
2722 if (SSL_SESSION_has_ticket(ss)) /* 1.1.0 */
2723 debug_printf("The session has a ticket, life %lu seconds\n",
2724 SSL_SESSION_get_ticket_lifetime_hint(ss));
2729 /* Record the certificate we presented */
2731 X509 * crt = SSL_get_certificate(server_ssl);
2732 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
2735 /* Only used by the server-side tls (tls_in), including tls_getc.
2736 Client-side (tls_out) reads (seem to?) go via
2737 smtp_read_response()/ip_recv().
2738 Hence no need to duplicate for _in and _out.
2740 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
2741 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
2742 ssl_xfer_eof = ssl_xfer_error = FALSE;
2744 receive_getc = tls_getc;
2745 receive_getbuf = tls_getbuf;
2746 receive_get_cache = tls_get_cache;
2747 receive_ungetc = tls_ungetc;
2748 receive_feof = tls_feof;
2749 receive_ferror = tls_ferror;
2750 receive_smtp_buffered = tls_smtp_buffered;
2752 tls_in.active.sock = fileno(smtp_out);
2753 tls_in.active.tls_ctx = NULL; /* not using explicit ctx for server-side */
2761 tls_client_basic_ctx_init(SSL_CTX * ctx,
2762 host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo,
2766 /* stick to the old behaviour for compatibility if tls_verify_certificates is
2767 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
2768 the specified host patterns if one of them is defined */
2770 if ( ( !ob->tls_verify_hosts
2771 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
2773 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
2775 client_verify_optional = FALSE;
2776 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
2777 client_verify_optional = TRUE;
2781 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
2782 ob->tls_crl, host, client_verify_optional, verify_callback_client,
2786 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
2788 cbinfo->verify_cert_hostnames =
2790 string_domain_utf8_to_alabel(host->name, NULL);
2794 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
2795 cbinfo->verify_cert_hostnames);
2803 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
2806 const char * hostnames[2] = { CS host->name, NULL };
2809 if (DANESSL_init(ssl, NULL, hostnames) != 1)
2810 return tls_error(US"hostnames load", host, NULL, errstr);
2812 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
2813 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2814 ) if (rr->type == T_TLSA && rr->size > 3)
2816 const uschar * p = rr->data;
2817 uint8_t usage, selector, mtype;
2818 const char * mdname;
2822 /* Only DANE-TA(2) and DANE-EE(3) are supported */
2823 if (usage != 2 && usage != 3) continue;
2830 default: continue; /* Only match-types 0, 1, 2 are supported */
2831 case 0: mdname = NULL; break;
2832 case 1: mdname = "sha256"; break;
2833 case 2: mdname = "sha512"; break;
2837 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
2840 return tls_error(US"tlsa load", host, NULL, errstr);
2841 case 0: /* action not taken */
2845 tls_out.tlsa_usage |= 1<<usage;
2851 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
2854 #endif /*SUPPORT_DANE*/
2858 #ifdef EXPERIMENTAL_TLS_RESUME
2859 /* On the client, get any stashed session for the given IP from hints db
2860 and apply it to the ssl-connection for attempted resumption. */
2863 tls_retrieve_session(tls_support * tlsp, SSL * ssl, const uschar * key)
2865 tlsp->resumption |= RESUME_SUPPORTED;
2866 if (tlsp->host_resumable)
2868 dbdata_tls_session * dt;
2870 open_db dbblock, * dbm_file;
2872 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
2873 DEBUG(D_tls) debug_printf("checking for resumable session for %s\n", key);
2874 if ((dbm_file = dbfn_open(US"tls", O_RDONLY, &dbblock, FALSE, FALSE)))
2876 /* key for the db is the IP */
2877 if ((dt = dbfn_read_with_length(dbm_file, key, &len)))
2879 SSL_SESSION * ss = NULL;
2880 const uschar * sess_asn1 = dt->session;
2882 len -= sizeof(dbdata_tls_session);
2883 if (!(d2i_SSL_SESSION(&ss, &sess_asn1, (long)len)))
2887 ERR_error_string_n(ERR_get_error(),
2888 ssl_errstring, sizeof(ssl_errstring));
2889 debug_printf("decoding session: %s\n", ssl_errstring);
2892 #ifdef EXIM_HAVE_SESSION_TICKET
2893 else if ( SSL_SESSION_get_ticket_lifetime_hint(ss) + dt->time_stamp
2896 DEBUG(D_tls) debug_printf("session expired\n");
2897 dbfn_delete(dbm_file, key);
2900 else if (!SSL_set_session(ssl, ss))
2904 ERR_error_string_n(ERR_get_error(),
2905 ssl_errstring, sizeof(ssl_errstring));
2906 debug_printf("applying session to ssl: %s\n", ssl_errstring);
2911 DEBUG(D_tls) debug_printf("good session\n");
2912 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
2913 tlsp->verify_override = dt->verify_override;
2914 tlsp->ocsp = dt->ocsp;
2918 DEBUG(D_tls) debug_printf("no session record\n");
2919 dbfn_close(dbm_file);
2925 /* On the client, save the session for later resumption */
2928 tls_save_session_cb(SSL * ssl, SSL_SESSION * ss)
2930 tls_ext_ctx_cb * cbinfo = SSL_get_ex_data(ssl, tls_exdata_idx);
2933 DEBUG(D_tls) debug_printf("tls_save_session_cb\n");
2935 if (!cbinfo || !(tlsp = cbinfo->tlsp)->host_resumable) return 0;
2937 # ifdef OPENSSL_HAVE_NUM_TICKETS
2938 if (SSL_SESSION_is_resumable(ss)) /* 1.1.1 */
2941 int len = i2d_SSL_SESSION(ss, NULL);
2942 int dlen = sizeof(dbdata_tls_session) + len;
2943 dbdata_tls_session * dt = store_get(dlen, TRUE);
2944 uschar * s = dt->session;
2945 open_db dbblock, * dbm_file;
2947 DEBUG(D_tls) debug_printf("session is resumable\n");
2948 tlsp->resumption |= RESUME_SERVER_TICKET; /* server gave us a ticket */
2950 dt->verify_override = tlsp->verify_override;
2951 dt->ocsp = tlsp->ocsp;
2952 (void) i2d_SSL_SESSION(ss, &s); /* s gets bumped to end */
2954 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
2956 const uschar * key = cbinfo->host->address;
2957 dbfn_delete(dbm_file, key);
2958 dbfn_write(dbm_file, key, dt, dlen);
2959 dbfn_close(dbm_file);
2960 DEBUG(D_tls) debug_printf("wrote session (len %u) to db\n",
2969 tls_client_ctx_resume_prehandshake(
2970 exim_openssl_client_tls_ctx * exim_client_ctx, tls_support * tlsp,
2971 smtp_transport_options_block * ob, host_item * host)
2973 /* Should the client request a session resumption ticket? */
2974 if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
2976 tlsp->host_resumable = TRUE;
2978 SSL_CTX_set_session_cache_mode(exim_client_ctx->ctx,
2979 SSL_SESS_CACHE_CLIENT
2980 | SSL_SESS_CACHE_NO_INTERNAL | SSL_SESS_CACHE_NO_AUTO_CLEAR);
2981 SSL_CTX_sess_set_new_cb(exim_client_ctx->ctx, tls_save_session_cb);
2986 tls_client_ssl_resume_prehandshake(SSL * ssl, tls_support * tlsp,
2987 host_item * host, uschar ** errstr)
2989 if (tlsp->host_resumable)
2992 debug_printf("tls_resumption_hosts overrides openssl_options, enabling tickets\n");
2993 SSL_clear_options(ssl, SSL_OP_NO_TICKET);
2995 tls_exdata_idx = SSL_get_ex_new_index(0, 0, 0, 0, 0);
2996 if (!SSL_set_ex_data(ssl, tls_exdata_idx, client_static_cbinfo))
2998 tls_error(US"set ex_data", host, NULL, errstr);
3001 debug_printf("tls_exdata_idx %d cbinfo %p\n", tls_exdata_idx, client_static_cbinfo);
3004 tlsp->resumption = RESUME_SUPPORTED;
3005 /* Pick up a previous session, saved on an old ticket */
3006 tls_retrieve_session(tlsp, ssl, host->address);
3011 tls_client_resume_posthandshake(exim_openssl_client_tls_ctx * exim_client_ctx,
3014 if (SSL_session_reused(exim_client_ctx->ssl))
3016 DEBUG(D_tls) debug_printf("The session was reused\n");
3017 tlsp->resumption |= RESUME_USED;
3020 #endif /* EXPERIMENTAL_TLS_RESUME */
3023 /*************************************************
3024 * Start a TLS session in a client *
3025 *************************************************/
3027 /* Called from the smtp transport after STARTTLS has been accepted.
3030 cctx connection context
3031 conn_args connection details
3032 cookie datum for randomness; can be NULL
3033 tlsp record details of TLS channel configuration here; must be non-NULL
3034 errstr error string pointer
3036 Returns: TRUE for success with TLS session context set in connection context,
3041 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
3042 void * cookie, tls_support * tlsp, uschar ** errstr)
3044 host_item * host = conn_args->host; /* for msgs and option-tests */
3045 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
3046 smtp_transport_options_block * ob = tb
3047 ? (smtp_transport_options_block *)tb->options_block
3048 : &smtp_transport_option_defaults;
3049 exim_openssl_client_tls_ctx * exim_client_ctx;
3050 uschar * expciphers;
3052 static uschar peerdn[256];
3054 #ifndef DISABLE_OCSP
3055 BOOL request_ocsp = FALSE;
3056 BOOL require_ocsp = FALSE;
3060 store_pool = POOL_PERM;
3061 exim_client_ctx = store_get(sizeof(exim_openssl_client_tls_ctx), FALSE);
3062 exim_client_ctx->corked = NULL;
3066 tlsp->tlsa_usage = 0;
3069 #ifndef DISABLE_OCSP
3071 # ifdef SUPPORT_DANE
3072 if ( conn_args->dane
3073 && ob->hosts_request_ocsp[0] == '*'
3074 && ob->hosts_request_ocsp[1] == '\0'
3077 /* Unchanged from default. Use a safer one under DANE */
3078 request_ocsp = TRUE;
3079 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
3080 " {= {4}{$tls_out_tlsa_usage}} } "
3086 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK))
3087 request_ocsp = TRUE;
3089 # ifdef SUPPORT_DANE
3093 verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3097 rc = tls_init(&exim_client_ctx->ctx, host, NULL,
3098 ob->tls_certificate, ob->tls_privatekey,
3099 #ifndef DISABLE_OCSP
3100 (void *)(long)request_ocsp,
3102 cookie, &client_static_cbinfo, tlsp, errstr);
3103 if (rc != OK) return FALSE;
3105 tlsp->certificate_verified = FALSE;
3106 client_verify_callback_called = FALSE;
3110 if (conn_args->dane)
3112 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
3113 other failures should be treated as problems. */
3114 if (ob->dane_require_tls_ciphers &&
3115 !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
3116 &expciphers, errstr))
3118 if (expciphers && *expciphers == '\0')
3123 !expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
3124 &expciphers, errstr))
3127 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
3128 are separated by underscores. So that I can use either form in my tests, and
3129 also for general convenience, we turn underscores into hyphens here. */
3133 uschar *s = expciphers;
3134 while (*s) { if (*s == '_') *s = '-'; s++; }
3135 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
3136 if (!SSL_CTX_set_cipher_list(exim_client_ctx->ctx, CS expciphers))
3138 tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
3144 if (conn_args->dane)
3146 SSL_CTX_set_verify(exim_client_ctx->ctx,
3147 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
3148 verify_callback_client_dane);
3150 if (!DANESSL_library_init())
3152 tls_error(US"library init", host, NULL, errstr);
3155 if (DANESSL_CTX_init(exim_client_ctx->ctx) <= 0)
3157 tls_error(US"context init", host, NULL, errstr);
3165 if (tls_client_basic_ctx_init(exim_client_ctx->ctx, host, ob,
3166 client_static_cbinfo, errstr) != OK)
3169 #ifdef EXPERIMENTAL_TLS_RESUME
3170 tls_client_ctx_resume_prehandshake(exim_client_ctx, tlsp, ob, host);
3174 if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx)))
3176 tls_error(US"SSL_new", host, NULL, errstr);
3179 SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx));
3181 SSL_set_fd(exim_client_ctx->ssl, cctx->sock);
3182 SSL_set_connect_state(exim_client_ctx->ssl);
3186 if (!expand_check(ob->tls_sni, US"tls_sni", &tlsp->sni, errstr))
3190 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
3192 else if (!Ustrlen(tlsp->sni))
3196 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
3197 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tlsp->sni);
3198 SSL_set_tlsext_host_name(exim_client_ctx->ssl, tlsp->sni);
3200 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
3207 if (conn_args->dane)
3208 if (dane_tlsa_load(exim_client_ctx->ssl, host, &conn_args->tlsa_dnsa, errstr) != OK)
3212 #ifndef DISABLE_OCSP
3213 /* Request certificate status at connection-time. If the server
3214 does OCSP stapling we will get the callback (set in tls_init()) */
3215 # ifdef SUPPORT_DANE
3219 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
3220 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
3222 { /* Re-eval now $tls_out_tlsa_usage is populated. If
3223 this means we avoid the OCSP request, we wasted the setup
3224 cost in tls_init(). */
3225 require_ocsp = verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
3226 request_ocsp = require_ocsp
3227 || verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3234 SSL_set_tlsext_status_type(exim_client_ctx->ssl, TLSEXT_STATUSTYPE_ocsp);
3235 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
3236 tlsp->ocsp = OCSP_NOT_RESP;
3240 #ifdef EXPERIMENTAL_TLS_RESUME
3241 if (!tls_client_ssl_resume_prehandshake(exim_client_ctx->ssl, tlsp, host,
3246 #ifndef DISABLE_EVENT
3247 client_static_cbinfo->event_action = tb ? tb->event_action : NULL;
3250 /* There doesn't seem to be a built-in timeout on connection. */
3252 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
3253 sigalrm_seen = FALSE;
3254 ALARM(ob->command_timeout);
3255 rc = SSL_connect(exim_client_ctx->ssl);
3259 if (conn_args->dane)
3260 DANESSL_cleanup(exim_client_ctx->ssl);
3265 tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, errstr);
3271 debug_printf("SSL_connect succeeded\n");
3272 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3274 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
3275 SSL_SESSION_print_keylog(bp, SSL_get_session(exim_client_ctx->ssl));
3281 #ifdef EXPERIMENTAL_TLS_RESUME
3282 tls_client_resume_posthandshake(exim_client_ctx, tlsp);
3285 peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn));
3287 tlsp->cipher = construct_cipher_name(exim_client_ctx->ssl, &tlsp->bits);
3288 tlsp->cipher_stdname = cipher_stdname_ssl(exim_client_ctx->ssl);
3290 /* Record the certificate we presented */
3292 X509 * crt = SSL_get_certificate(exim_client_ctx->ssl);
3293 tlsp->ourcert = crt ? X509_dup(crt) : NULL;
3296 tlsp->active.sock = cctx->sock;
3297 tlsp->active.tls_ctx = exim_client_ctx;
3298 cctx->tls_ctx = exim_client_ctx;
3307 tls_refill(unsigned lim)
3312 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
3313 ssl_xfer_buffer, ssl_xfer_buffer_size);
3315 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3316 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer,
3317 MIN(ssl_xfer_buffer_size, lim));
3318 error = SSL_get_error(server_ssl, inbytes);
3319 if (smtp_receive_timeout > 0) ALARM_CLR(0);
3321 if (had_command_timeout) /* set by signal handler */
3322 smtp_command_timeout_exit(); /* does not return */
3323 if (had_command_sigterm)
3324 smtp_command_sigterm_exit();
3325 if (had_data_timeout)
3326 smtp_data_timeout_exit();
3327 if (had_data_sigint)
3328 smtp_data_sigint_exit();
3330 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
3331 closed down, not that the socket itself has been closed down. Revert to
3332 non-SSL handling. */
3336 case SSL_ERROR_NONE:
3339 case SSL_ERROR_ZERO_RETURN:
3340 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3342 if (SSL_get_shutdown(server_ssl) == SSL_RECEIVED_SHUTDOWN)
3343 SSL_shutdown(server_ssl);
3345 tls_close(NULL, TLS_NO_SHUTDOWN);
3348 /* Handle genuine errors */
3350 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3351 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
3352 ssl_xfer_error = TRUE;
3356 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
3357 DEBUG(D_tls) if (error == SSL_ERROR_SYSCALL)
3358 debug_printf(" - syscall %s\n", strerror(errno));
3359 ssl_xfer_error = TRUE;
3363 #ifndef DISABLE_DKIM
3364 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
3366 ssl_xfer_buffer_hwm = inbytes;
3367 ssl_xfer_buffer_lwm = 0;
3372 /*************************************************
3373 * TLS version of getc *
3374 *************************************************/
3376 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
3377 it refills the buffer via the SSL reading function.
3379 Arguments: lim Maximum amount to read/buffer
3380 Returns: the next character or EOF
3382 Only used by the server-side TLS.
3386 tls_getc(unsigned lim)
3388 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
3389 if (!tls_refill(lim))
3390 return ssl_xfer_error ? EOF : smtp_getc(lim);
3392 /* Something in the buffer; return next uschar */
3394 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
3398 tls_getbuf(unsigned * len)
3403 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
3404 if (!tls_refill(*len))
3406 if (!ssl_xfer_error) return smtp_getbuf(len);
3411 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
3413 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
3414 ssl_xfer_buffer_lwm += size;
3423 #ifndef DISABLE_DKIM
3424 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
3426 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
3432 tls_could_read(void)
3434 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm || SSL_pending(server_ssl) > 0;
3438 /*************************************************
3439 * Read bytes from TLS channel *
3440 *************************************************/
3444 ct_ctx client context pointer, or NULL for the one global server context
3448 Returns: the number of bytes read
3449 -1 after a failed read, including EOF
3451 Only used by the client-side TLS.
3455 tls_read(void * ct_ctx, uschar *buff, size_t len)
3457 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl : server_ssl;
3461 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
3462 buff, (unsigned int)len);
3464 inbytes = SSL_read(ssl, CS buff, len);
3465 error = SSL_get_error(ssl, inbytes);
3467 if (error == SSL_ERROR_ZERO_RETURN)
3469 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3472 else if (error != SSL_ERROR_NONE)
3482 /*************************************************
3483 * Write bytes down TLS channel *
3484 *************************************************/
3488 ct_ctx client context pointer, or NULL for the one global server context
3491 more further data expected soon
3493 Returns: the number of bytes after a successful write,
3494 -1 after a failed write
3496 Used by both server-side and client-side TLS.
3500 tls_write(void * ct_ctx, const uschar *buff, size_t len, BOOL more)
3503 int outbytes, error;
3505 ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl : server_ssl;
3506 static gstring * server_corked = NULL;
3507 gstring ** corkedp = ct_ctx
3508 ? &((exim_openssl_client_tls_ctx *)ct_ctx)->corked : &server_corked;
3509 gstring * corked = *corkedp;
3511 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
3512 buff, (unsigned long)len, more ? ", more" : "");
3514 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
3515 "more" is notified. This hack is only ok if small amounts are involved AND only
3516 one stream does it, in one context (i.e. no store reset). Currently it is used
3517 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only.
3518 We support callouts done by the server process by using a separate client
3519 context for the stashed information. */
3520 /* + if PIPE_COMMAND, banner & ehlo-resp for smmtp-on-connect. Suspect there's
3521 a store reset there, so use POOL_PERM. */
3522 /* + if CHUNKING, cmds EHLO,MAIL,RCPT(s),BDAT */
3524 if ((more || corked))
3526 #ifdef SUPPORT_PIPE_CONNECT
3527 int save_pool = store_pool;
3528 store_pool = POOL_PERM;
3531 corked = string_catn(corked, buff, len);
3533 #ifdef SUPPORT_PIPE_CONNECT
3534 store_pool = save_pool;
3542 buff = CUS corked->s;
3547 for (int left = len; left > 0;)
3549 DEBUG(D_tls) debug_printf("SSL_write(%p, %p, %d)\n", ssl, buff, left);
3550 outbytes = SSL_write(ssl, CS buff, left);
3551 error = SSL_get_error(ssl, outbytes);
3552 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
3556 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3557 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
3560 case SSL_ERROR_NONE:
3565 case SSL_ERROR_ZERO_RETURN:
3566 log_write(0, LOG_MAIN, "SSL channel closed on write");
3569 case SSL_ERROR_SYSCALL:
3570 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
3571 sender_fullhost ? sender_fullhost : US"<unknown>",
3576 log_write(0, LOG_MAIN, "SSL_write error %d", error);
3585 /*************************************************
3586 * Close down a TLS session *
3587 *************************************************/
3589 /* This is also called from within a delivery subprocess forked from the
3590 daemon, to shut down the TLS library, without actually doing a shutdown (which
3591 would tamper with the SSL session in the parent process).
3594 ct_ctx client TLS context pointer, or NULL for the one global server context
3595 shutdown 1 if TLS close-alert is to be sent,
3596 2 if also response to be waited for
3600 Used by both server-side and client-side TLS.
3604 tls_close(void * ct_ctx, int shutdown)
3606 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
3607 SSL_CTX **ctxp = o_ctx ? &o_ctx->ctx : &server_ctx;
3608 SSL **sslp = o_ctx ? &o_ctx->ssl : &server_ssl;
3609 int *fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
3611 if (*fdp < 0) return; /* TLS was not active */
3616 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
3617 shutdown > 1 ? " (with response-wait)" : "");
3619 if ( (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
3623 rc = SSL_shutdown(*sslp); /* wait for response */
3627 if (rc < 0) DEBUG(D_tls)
3629 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3630 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
3634 if (!o_ctx) /* server side */
3636 #ifndef DISABLE_OCSP
3637 sk_X509_pop_free(server_static_cbinfo->verify_stack, X509_free);
3638 server_static_cbinfo->verify_stack = NULL;
3641 receive_getc = smtp_getc;
3642 receive_getbuf = smtp_getbuf;
3643 receive_get_cache = smtp_get_cache;
3644 receive_ungetc = smtp_ungetc;
3645 receive_feof = smtp_feof;
3646 receive_ferror = smtp_ferror;
3647 receive_smtp_buffered = smtp_buffered;
3648 tls_in.active.tls_ctx = NULL;
3650 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
3653 SSL_CTX_free(*ctxp);
3663 /*************************************************
3664 * Let tls_require_ciphers be checked at startup *
3665 *************************************************/
3667 /* The tls_require_ciphers option, if set, must be something which the
3670 Returns: NULL on success, or error message
3674 tls_validate_require_cipher(void)
3677 uschar *s, *expciphers, *err;
3681 if (!(tls_require_ciphers && *tls_require_ciphers))
3684 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
3686 return US"failed to expand tls_require_ciphers";
3688 if (!(expciphers && *expciphers))
3691 /* normalisation ripped from above */
3693 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
3697 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
3698 if (!(ctx = SSL_CTX_new(TLS_server_method())))
3700 if (!(ctx = SSL_CTX_new(SSLv23_server_method())))
3703 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3704 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
3708 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
3710 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
3712 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3713 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
3714 expciphers, ssl_errstring);
3725 /*************************************************
3726 * Report the library versions. *
3727 *************************************************/
3729 /* There have historically been some issues with binary compatibility in
3730 OpenSSL libraries; if Exim (like many other applications) is built against
3731 one version of OpenSSL but the run-time linker picks up another version,
3732 it can result in serious failures, including crashing with a SIGSEGV. So
3733 report the version found by the compiler and the run-time version.
3735 Note: some OS vendors backport security fixes without changing the version
3736 number/string, and the version date remains unchanged. The _build_ date
3737 will change, so we can more usefully assist with version diagnosis by also
3738 reporting the build date.
3740 Arguments: a FILE* to print the results to
3745 tls_version_report(FILE *f)
3747 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
3750 OPENSSL_VERSION_TEXT,
3751 SSLeay_version(SSLEAY_VERSION),
3752 SSLeay_version(SSLEAY_BUILT_ON));
3753 /* third line is 38 characters for the %s and the line is 73 chars long;
3754 the OpenSSL output includes a "built on: " prefix already. */
3760 /*************************************************
3761 * Random number generation *
3762 *************************************************/
3764 /* Pseudo-random number generation. The result is not expected to be
3765 cryptographically strong but not so weak that someone will shoot themselves
3766 in the foot using it as a nonce in input in some email header scheme or
3767 whatever weirdness they'll twist this into. The result should handle fork()
3768 and avoid repeating sequences. OpenSSL handles that for us.
3772 Returns a random number in range [0, max-1]
3776 vaguely_random_number(int max)
3780 static pid_t pidlast = 0;
3782 uschar smallbuf[sizeof(r)];
3788 if (pidnow != pidlast)
3790 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
3791 is unique for each thread", this doesn't apparently apply across processes,
3792 so our own warning from vaguely_random_number_fallback() applies here too.
3793 Fix per PostgreSQL. */
3799 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
3803 gettimeofday(&r.tv, NULL);
3806 RAND_seed(US (&r), sizeof(r));
3808 /* We're after pseudo-random, not random; if we still don't have enough data
3809 in the internal PRNG then our options are limited. We could sleep and hope
3810 for entropy to come along (prayer technique) but if the system is so depleted
3811 in the first place then something is likely to just keep taking it. Instead,
3812 we'll just take whatever little bit of pseudo-random we can still manage to
3815 needed_len = sizeof(r);
3816 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
3817 asked for a number less than 10. */
3818 for (r = max, i = 0; r; ++i)
3824 #ifdef EXIM_HAVE_RAND_PSEUDO
3825 /* We do not care if crypto-strong */
3826 i = RAND_pseudo_bytes(smallbuf, needed_len);
3828 i = RAND_bytes(smallbuf, needed_len);
3834 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
3835 return vaguely_random_number_fallback(max);
3839 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
3842 /* We don't particularly care about weighted results; if someone wants
3843 smooth distribution and cares enough then they should submit a patch then. */
3850 /*************************************************
3851 * OpenSSL option parse *
3852 *************************************************/
3854 /* Parse one option for tls_openssl_options_parse below
3857 name one option name
3858 value place to store a value for it
3859 Returns success or failure in parsing
3865 tls_openssl_one_option_parse(uschar *name, long *value)
3868 int last = exim_openssl_options_size;
3869 while (last > first)
3871 int middle = (first + last)/2;
3872 int c = Ustrcmp(name, exim_openssl_options[middle].name);
3875 *value = exim_openssl_options[middle].value;
3889 /*************************************************
3890 * OpenSSL option parsing logic *
3891 *************************************************/
3893 /* OpenSSL has a number of compatibility options which an administrator might
3894 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
3895 we look like log_selector.
3898 option_spec the administrator-supplied string of options
3899 results ptr to long storage for the options bitmap
3900 Returns success or failure
3904 tls_openssl_options_parse(uschar *option_spec, long *results)
3909 BOOL adding, item_parsed;
3911 /* Server: send no (<= TLS1.2) session tickets */
3912 result = SSL_OP_NO_TICKET;
3914 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
3915 * from default because it increases BEAST susceptibility. */
3916 #ifdef SSL_OP_NO_SSLv2
3917 result |= SSL_OP_NO_SSLv2;
3919 #ifdef SSL_OP_NO_SSLv3
3920 result |= SSL_OP_NO_SSLv3;
3922 #ifdef SSL_OP_SINGLE_DH_USE
3923 result |= SSL_OP_SINGLE_DH_USE;
3932 for (uschar * s = option_spec; *s; /**/)
3934 while (isspace(*s)) ++s;
3937 if (*s != '+' && *s != '-')
3939 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
3940 "+ or - expected but found \"%s\"\n", s);
3943 adding = *s++ == '+';
3944 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
3947 item_parsed = tls_openssl_one_option_parse(s, &item);
3951 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
3954 DEBUG(D_tls) debug_printf("openssl option, %s %8lx: %lx (%s)\n",
3955 adding ? "adding to " : "removing from", result, item, s);
3967 #endif /*!MACRO_PREDEF*/
3970 /* End of tls-openssl.c */