Move certificate name checking to mainline, default enabled
[exim.git] / src / src / tls-openssl.c
CommitLineData
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1/*************************************************
2* Exim - an Internet mail transport agent *
3*************************************************/
4
5a66c31b 5/* Copyright (c) University of Cambridge 1995 - 2014 */
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6/* See the file NOTICE for conditions of use and distribution. */
7
f5d78688
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8/* Portions Copyright (c) The OpenSSL Project 1999 */
9
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10/* This module provides the TLS (aka SSL) support for Exim using the OpenSSL
11library. It is #included into the tls.c file when that library is used. The
12code herein is based on a patch that was originally contributed by Steve
13Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara.
14
15No cryptographic code is included in Exim. All this module does is to call
16functions from the OpenSSL library. */
17
18
19/* Heading stuff */
20
21#include <openssl/lhash.h>
22#include <openssl/ssl.h>
23#include <openssl/err.h>
24#include <openssl/rand.h>
f2de3a33 25#ifndef DISABLE_OCSP
e51c7be2 26# include <openssl/ocsp.h>
3f7eeb86 27#endif
85098ee7
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28#ifdef EXPERIMENTAL_DANE
29# include <danessl.h>
30#endif
31
3f7eeb86 32
f2de3a33
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33#ifndef DISABLE_OCSP
34# define EXIM_OCSP_SKEW_SECONDS (300L)
35# define EXIM_OCSP_MAX_AGE (-1L)
3f7eeb86 36#endif
059ec3d9 37
3bcbbbe2 38#if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
e51c7be2 39# define EXIM_HAVE_OPENSSL_TLSEXT
3bcbbbe2 40#endif
2dfb468b
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41#if OPENSSL_VERSION_NUMBER >= 0x010100000L
42# define EXIM_HAVE_OPENSSL_CHECKHOST
43#endif
44#if OPENSSL_VERSION_NUMBER >= 0x010000000L \
45 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
46# define EXIM_HAVE_OPENSSL_CHECKHOST
47#endif
3bcbbbe2 48
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49#if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
50# warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
51# define DISABLE_OCSP
52#endif
53
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54/* Structure for collecting random data for seeding. */
55
56typedef struct randstuff {
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57 struct timeval tv;
58 pid_t p;
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59} randstuff;
60
61/* Local static variables */
62
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63static BOOL client_verify_callback_called = FALSE;
64static BOOL server_verify_callback_called = FALSE;
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65static const uschar *sid_ctx = US"exim";
66
d4f09789
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67/* We have three different contexts to care about.
68
69Simple case: client, `client_ctx`
70 As a client, we can be doing a callout or cut-through delivery while receiving
71 a message. So we have a client context, which should have options initialised
72 from the SMTP Transport.
73
74Server:
75 There are two cases: with and without ServerNameIndication from the client.
76 Given TLS SNI, we can be using different keys, certs and various other
77 configuration settings, because they're re-expanded with $tls_sni set. This
78 allows vhosting with TLS. This SNI is sent in the handshake.
79 A client might not send SNI, so we need a fallback, and an initial setup too.
80 So as a server, we start out using `server_ctx`.
81 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
82 `server_sni` from `server_ctx` and then initialise settings by re-expanding
83 configuration.
84*/
85
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86static SSL_CTX *client_ctx = NULL;
87static SSL_CTX *server_ctx = NULL;
88static SSL *client_ssl = NULL;
89static SSL *server_ssl = NULL;
389ca47a 90
35731706 91#ifdef EXIM_HAVE_OPENSSL_TLSEXT
817d9f57 92static SSL_CTX *server_sni = NULL;
35731706 93#endif
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94
95static char ssl_errstring[256];
96
97static int ssl_session_timeout = 200;
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98static BOOL client_verify_optional = FALSE;
99static BOOL server_verify_optional = FALSE;
059ec3d9 100
f5d78688 101static BOOL reexpand_tls_files_for_sni = FALSE;
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102
103
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104typedef struct tls_ext_ctx_cb {
105 uschar *certificate;
106 uschar *privatekey;
f2de3a33 107#ifndef DISABLE_OCSP
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108 BOOL is_server;
109 union {
110 struct {
111 uschar *file;
112 uschar *file_expanded;
113 OCSP_RESPONSE *response;
114 } server;
115 struct {
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116 X509_STORE *verify_store; /* non-null if status requested */
117 BOOL verify_required;
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118 } client;
119 } u_ocsp;
3f7eeb86 120#endif
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121 uschar *dhparam;
122 /* these are cached from first expand */
123 uschar *server_cipher_list;
124 /* only passed down to tls_error: */
125 host_item *host;
e51c7be2 126 uschar * verify_cert_hostnames;
774ef2d7 127#ifdef EXPERIMENTAL_EVENT
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128 uschar * event_action;
129#endif
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130} tls_ext_ctx_cb;
131
132/* should figure out a cleanup of API to handle state preserved per
133implementation, for various reasons, which can be void * in the APIs.
134For now, we hack around it. */
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135tls_ext_ctx_cb *client_static_cbinfo = NULL;
136tls_ext_ctx_cb *server_static_cbinfo = NULL;
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137
138static int
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139setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
140 int (*cert_vfy_cb)(int, X509_STORE_CTX *) );
059ec3d9 141
3f7eeb86 142/* Callbacks */
3bcbbbe2 143#ifdef EXIM_HAVE_OPENSSL_TLSEXT
3f7eeb86 144static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
3bcbbbe2 145#endif
f2de3a33 146#ifndef DISABLE_OCSP
f5d78688 147static int tls_server_stapling_cb(SSL *s, void *arg);
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148#endif
149
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150
151/*************************************************
152* Handle TLS error *
153*************************************************/
154
155/* Called from lots of places when errors occur before actually starting to do
156the TLS handshake, that is, while the session is still in clear. Always returns
157DEFER for a server and FAIL for a client so that most calls can use "return
158tls_error(...)" to do this processing and then give an appropriate return. A
159single function is used for both server and client, because it is called from
160some shared functions.
161
162Argument:
163 prefix text to include in the logged error
164 host NULL if setting up a server;
165 the connected host if setting up a client
7199e1ee 166 msg error message or NULL if we should ask OpenSSL
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167
168Returns: OK/DEFER/FAIL
169*/
170
171static int
b8b1b5cb 172tls_error(uschar * prefix, const host_item * host, uschar * msg)
059ec3d9 173{
c562fd30 174if (!msg)
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175 {
176 ERR_error_string(ERR_get_error(), ssl_errstring);
5ca6d115 177 msg = (uschar *)ssl_errstring;
7199e1ee
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178 }
179
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180if (host)
181 {
182 log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection (%s): %s",
183 host->name, host->address, prefix, msg);
184 return FAIL;
185 }
186else
059ec3d9 187 {
7199e1ee 188 uschar *conn_info = smtp_get_connection_info();
5ca6d115 189 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
7199e1ee 190 conn_info += 5;
c562fd30 191 /* I'd like to get separated H= here, but too hard for now */
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192 log_write(0, LOG_MAIN, "TLS error on %s (%s): %s",
193 conn_info, prefix, msg);
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194 return DEFER;
195 }
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196}
197
198
199
200/*************************************************
201* Callback to generate RSA key *
202*************************************************/
203
204/*
205Arguments:
206 s SSL connection
207 export not used
208 keylength keylength
209
210Returns: pointer to generated key
211*/
212
213static RSA *
214rsa_callback(SSL *s, int export, int keylength)
215{
216RSA *rsa_key;
217export = export; /* Shut picky compilers up */
218DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
219rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL);
220if (rsa_key == NULL)
221 {
222 ERR_error_string(ERR_get_error(), ssl_errstring);
223 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
224 ssl_errstring);
225 return NULL;
226 }
227return rsa_key;
228}
229
230
231
f5d78688 232/* Extreme debug
f2de3a33 233#ifndef DISABLE_OCSP
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234void
235x509_store_dump_cert_s_names(X509_STORE * store)
236{
237STACK_OF(X509_OBJECT) * roots= store->objs;
238int i;
239static uschar name[256];
240
241for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
242 {
243 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
244 if(tmp_obj->type == X509_LU_X509)
245 {
246 X509 * current_cert= tmp_obj->data.x509;
247 X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name));
248 debug_printf(" %s\n", name);
249 }
250 }
251}
252#endif
253*/
254
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255
256/*************************************************
257* Callback for verification *
258*************************************************/
259
260/* The SSL library does certificate verification if set up to do so. This
261callback has the current yes/no state is in "state". If verification succeeded,
262we set up the tls_peerdn string. If verification failed, what happens depends
263on whether the client is required to present a verifiable certificate or not.
264
265If verification is optional, we change the state to yes, but still log the
266verification error. For some reason (it really would help to have proper
267documentation of OpenSSL), this callback function then gets called again, this
268time with state = 1. In fact, that's useful, because we can set up the peerdn
269value, but we must take care not to set the private verified flag on the second
270time through.
271
272Note: this function is not called if the client fails to present a certificate
273when asked. We get here only if a certificate has been received. Handling of
274optional verification for this case is done when requesting SSL to verify, by
275setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
276
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277May be called multiple times for different issues with a certificate, even
278for a given "depth" in the certificate chain.
279
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280Arguments:
281 state current yes/no state as 1/0
282 x509ctx certificate information.
a2ff477a 283 client TRUE for client startup, FALSE for server startup
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284
285Returns: 1 if verified, 0 if not
286*/
287
288static int
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289verify_callback(int state, X509_STORE_CTX *x509ctx,
290 tls_support *tlsp, BOOL *calledp, BOOL *optionalp)
059ec3d9 291{
421aff85 292X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
a7538db1 293int depth = X509_STORE_CTX_get_error_depth(x509ctx);
059ec3d9 294static uschar txt[256];
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295#ifdef EXPERIMENTAL_EVENT
296uschar * ev;
297uschar * yield;
298#endif
059ec3d9 299
e51c7be2 300X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
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301
302if (state == 0)
303 {
304 log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s",
a7538db1 305 depth,
421aff85 306 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)),
059ec3d9 307 txt);
a2ff477a 308 *calledp = TRUE;
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309 if (!*optionalp)
310 {
421aff85 311 tlsp->peercert = X509_dup(cert);
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312 return 0; /* reject */
313 }
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314 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
315 "tls_try_verify_hosts)\n");
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316 }
317
a7538db1 318else if (depth != 0)
059ec3d9 319 {
a7538db1 320 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, txt);
f2de3a33 321#ifndef DISABLE_OCSP
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322 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
323 { /* client, wanting stapling */
324 /* Add the server cert's signing chain as the one
325 for the verification of the OCSP stapled information. */
326
327 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
421aff85 328 cert))
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329 ERR_clear_error();
330 }
331#endif
774ef2d7 332#ifdef EXPERIMENTAL_EVENT
723fe533
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333 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
334 if (ev)
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335 {
336 tlsp->peercert = X509_dup(cert);
b30275b8 337 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
a7538db1
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338 {
339 log_write(0, LOG_MAIN, "SSL verify denied by event-action: "
b30275b8 340 "depth=%d cert=%s: %s", depth, txt, yield);
a7538db1 341 *calledp = TRUE;
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342 if (!*optionalp)
343 return 0; /* reject */
344 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
345 "(host in tls_try_verify_hosts)\n");
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346 }
347 X509_free(tlsp->peercert);
348 tlsp->peercert = NULL;
349 }
350#endif
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351 }
352else
353 {
e51c7be2 354 uschar * verify_cert_hostnames;
e51c7be2 355
a2ff477a 356 tlsp->peerdn = txt;
421aff85 357 tlsp->peercert = X509_dup(cert);
e51c7be2 358
e51c7be2
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359 if ( tlsp == &tls_out
360 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
361 /* client, wanting hostname check */
362
2dfb468b 363# if EXIM_HAVE_OPENSSL_CHECKHOST
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364# ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
365# define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
366# endif
8d692470
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367# ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
368# define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
369# endif
e51c7be2
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370 {
371 int sep = 0;
372 uschar * list = verify_cert_hostnames;
373 uschar * name;
d8e7834a
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374 int rc;
375 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
376 if ((rc = X509_check_host(cert, name, 0,
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377 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
378 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS)))
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379 {
380 if (rc < 0)
381 {
382 log_write(0, LOG_MAIN, "SSL verify error: internal error\n");
383 name = NULL;
384 }
e51c7be2 385 break;
d8e7834a 386 }
e51c7be2
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387 if (!name)
388 {
389 log_write(0, LOG_MAIN,
390 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
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391 *calledp = TRUE;
392 if (!*optionalp)
393 return 0; /* reject */
394 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
395 "tls_try_verify_hosts)\n");
e51c7be2
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396 }
397 }
398# else
399 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
400 {
401 log_write(0, LOG_MAIN,
402 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
a3ef7310
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403 *calledp = TRUE;
404 if (!*optionalp)
405 return 0; /* reject */
406 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
407 "tls_try_verify_hosts)\n");
e51c7be2
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408 }
409# endif
e51c7be2 410
774ef2d7 411#ifdef EXPERIMENTAL_EVENT
723fe533
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412 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
413 if (ev)
b30275b8 414 if ((yield = event_raise(ev, US"tls:cert", US"0")))
a7538db1
JH
415 {
416 log_write(0, LOG_MAIN, "SSL verify denied by event-action: "
b30275b8 417 "depth=0 cert=%s: %s", txt, yield);
a7538db1 418 *calledp = TRUE;
a3ef7310
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419 if (!*optionalp)
420 return 0; /* reject */
421 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
422 "(host in tls_try_verify_hosts)\n");
a7538db1 423 }
e51c7be2
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424#endif
425
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426 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
427 *calledp ? "" : " authenticated", txt);
428 if (!*calledp) tlsp->certificate_verified = TRUE;
429 *calledp = TRUE;
059ec3d9
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430 }
431
a7538db1 432return 1; /* accept, at least for this level */
059ec3d9
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433}
434
a2ff477a
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435static int
436verify_callback_client(int state, X509_STORE_CTX *x509ctx)
437{
f5d78688 438return verify_callback(state, x509ctx, &tls_out, &client_verify_callback_called, &client_verify_optional);
a2ff477a
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439}
440
441static int
442verify_callback_server(int state, X509_STORE_CTX *x509ctx)
443{
f5d78688 444return verify_callback(state, x509ctx, &tls_in, &server_verify_callback_called, &server_verify_optional);
a2ff477a
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445}
446
059ec3d9 447
e5cccda9 448#ifdef EXPERIMENTAL_DANE
53a7196b 449
e5cccda9
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450/* This gets called *by* the dane library verify callback, which interposes
451itself.
452*/
453static int
454verify_callback_client_dane(int state, X509_STORE_CTX * x509ctx)
455{
456X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
457static uschar txt[256];
774ef2d7 458#ifdef EXPERIMENTAL_EVENT
83b27293 459int depth = X509_STORE_CTX_get_error_depth(x509ctx);
b30275b8 460uschar * yield;
83b27293 461#endif
e5cccda9
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462
463X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
464
465DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s\n", txt);
466tls_out.peerdn = txt;
467tls_out.peercert = X509_dup(cert);
468
774ef2d7 469#ifdef EXPERIMENTAL_EVENT
83b27293
JH
470 if (client_static_cbinfo->event_action)
471 {
b30275b8
JH
472 if ((yield = event_raise(client_static_cbinfo->event_action,
473 US"tls:cert", string_sprintf("%d", depth))))
83b27293
JH
474 {
475 log_write(0, LOG_MAIN, "DANE verify denied by event-action: "
b30275b8 476 "depth=%d cert=%s: %s", depth, txt, yield);
83b27293
JH
477 tls_out.certificate_verified = FALSE;
478 return 0; /* reject */
479 }
480 if (depth != 0)
481 {
482 X509_free(tls_out.peercert);
483 tls_out.peercert = NULL;
484 }
485 }
486#endif
487
e5cccda9 488if (state == 1)
53a7196b 489 tls_out.dane_verified =
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490 tls_out.certificate_verified = TRUE;
491return 1;
492}
53a7196b
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493
494#endif /*EXPERIMENTAL_DANE*/
e5cccda9 495
059ec3d9
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496
497/*************************************************
498* Information callback *
499*************************************************/
500
501/* The SSL library functions call this from time to time to indicate what they
7be682ca
PP
502are doing. We copy the string to the debugging output when TLS debugging has
503been requested.
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504
505Arguments:
506 s the SSL connection
507 where
508 ret
509
510Returns: nothing
511*/
512
513static void
514info_callback(SSL *s, int where, int ret)
515{
516where = where;
517ret = ret;
518DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
519}
520
521
522
523/*************************************************
524* Initialize for DH *
525*************************************************/
526
527/* If dhparam is set, expand it, and load up the parameters for DH encryption.
528
529Arguments:
a799883d 530 dhparam DH parameter file or fixed parameter identity string
7199e1ee 531 host connected host, if client; NULL if server
059ec3d9
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532
533Returns: TRUE if OK (nothing to set up, or setup worked)
534*/
535
536static BOOL
b8b1b5cb 537init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host)
059ec3d9 538{
059ec3d9
PH
539BIO *bio;
540DH *dh;
541uschar *dhexpanded;
a799883d 542const char *pem;
059ec3d9
PH
543
544if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
545 return FALSE;
546
0df4ab80 547if (!dhexpanded || !*dhexpanded)
a799883d 548 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
a799883d 549else if (dhexpanded[0] == '/')
059ec3d9 550 {
0df4ab80 551 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
059ec3d9 552 {
7199e1ee 553 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
a799883d
PP
554 host, US strerror(errno));
555 return FALSE;
059ec3d9 556 }
a799883d
PP
557 }
558else
559 {
560 if (Ustrcmp(dhexpanded, "none") == 0)
059ec3d9 561 {
a799883d
PP
562 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
563 return TRUE;
059ec3d9 564 }
a799883d 565
0df4ab80 566 if (!(pem = std_dh_prime_named(dhexpanded)))
a799883d
PP
567 {
568 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
569 host, US strerror(errno));
570 return FALSE;
571 }
572 bio = BIO_new_mem_buf(CS pem, -1);
573 }
574
0df4ab80 575if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
a799883d 576 {
059ec3d9 577 BIO_free(bio);
a799883d
PP
578 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
579 host, NULL);
580 return FALSE;
581 }
582
583/* Even if it is larger, we silently return success rather than cause things
584 * to fail out, so that a too-large DH will not knock out all TLS; it's a
585 * debatable choice. */
586if ((8*DH_size(dh)) > tls_dh_max_bits)
587 {
588 DEBUG(D_tls)
589 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
590 8*DH_size(dh), tls_dh_max_bits);
591 }
592else
593 {
594 SSL_CTX_set_tmp_dh(sctx, dh);
595 DEBUG(D_tls)
596 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
597 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
059ec3d9
PH
598 }
599
a799883d
PP
600DH_free(dh);
601BIO_free(bio);
602
603return TRUE;
059ec3d9
PH
604}
605
606
607
608
f2de3a33 609#ifndef DISABLE_OCSP
3f7eeb86
PP
610/*************************************************
611* Load OCSP information into state *
612*************************************************/
613
f5d78688 614/* Called to load the server OCSP response from the given file into memory, once
3f7eeb86
PP
615caller has determined this is needed. Checks validity. Debugs a message
616if invalid.
617
618ASSUMES: single response, for single cert.
619
620Arguments:
621 sctx the SSL_CTX* to update
622 cbinfo various parts of session state
623 expanded the filename putatively holding an OCSP response
624
625*/
626
627static void
f5d78688 628ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
3f7eeb86
PP
629{
630BIO *bio;
631OCSP_RESPONSE *resp;
632OCSP_BASICRESP *basic_response;
633OCSP_SINGLERESP *single_response;
634ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
635X509_STORE *store;
636unsigned long verify_flags;
637int status, reason, i;
638
f5d78688
JH
639cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
640if (cbinfo->u_ocsp.server.response)
3f7eeb86 641 {
f5d78688
JH
642 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
643 cbinfo->u_ocsp.server.response = NULL;
3f7eeb86
PP
644 }
645
f5d78688 646bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb");
3f7eeb86
PP
647if (!bio)
648 {
649 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
f5d78688 650 cbinfo->u_ocsp.server.file_expanded);
3f7eeb86
PP
651 return;
652 }
653
654resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
655BIO_free(bio);
656if (!resp)
657 {
658 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
659 return;
660 }
661
662status = OCSP_response_status(resp);
663if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
664 {
665 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
666 OCSP_response_status_str(status), status);
f5d78688 667 goto bad;
3f7eeb86
PP
668 }
669
670basic_response = OCSP_response_get1_basic(resp);
671if (!basic_response)
672 {
673 DEBUG(D_tls)
674 debug_printf("OCSP response parse error: unable to extract basic response.\n");
f5d78688 675 goto bad;
3f7eeb86
PP
676 }
677
678store = SSL_CTX_get_cert_store(sctx);
679verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
680
681/* May need to expose ability to adjust those flags?
682OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
683OCSP_TRUSTOTHER OCSP_NOINTERN */
684
685i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
686if (i <= 0)
687 {
688 DEBUG(D_tls) {
689 ERR_error_string(ERR_get_error(), ssl_errstring);
690 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
f5d78688
JH
691 }
692 goto bad;
3f7eeb86
PP
693 }
694
695/* Here's the simplifying assumption: there's only one response, for the
696one certificate we use, and nothing for anything else in a chain. If this
697proves false, we need to extract a cert id from our issued cert
698(tls_certificate) and use that for OCSP_resp_find_status() (which finds the
699right cert in the stack and then calls OCSP_single_get0_status()).
700
701I'm hoping to avoid reworking a bunch more of how we handle state here. */
702single_response = OCSP_resp_get0(basic_response, 0);
703if (!single_response)
704 {
705 DEBUG(D_tls)
706 debug_printf("Unable to get first response from OCSP basic response.\n");
f5d78688 707 goto bad;
3f7eeb86
PP
708 }
709
710status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
f5d78688 711if (status != V_OCSP_CERTSTATUS_GOOD)
3f7eeb86 712 {
f5d78688
JH
713 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
714 OCSP_cert_status_str(status), status,
715 OCSP_crl_reason_str(reason), reason);
716 goto bad;
3f7eeb86
PP
717 }
718
719if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
720 {
721 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
f5d78688 722 goto bad;
3f7eeb86
PP
723 }
724
f5d78688 725supply_response:
018058b2 726 cbinfo->u_ocsp.server.response = resp;
f5d78688
JH
727return;
728
729bad:
018058b2
JH
730 if (running_in_test_harness)
731 {
732 extern char ** environ;
733 uschar ** p;
734 for (p = USS environ; *p != NULL; p++)
735 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
736 {
737 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
738 goto supply_response;
739 }
740 }
f5d78688 741return;
3f7eeb86 742}
f2de3a33 743#endif /*!DISABLE_OCSP*/
3f7eeb86
PP
744
745
746
747
059ec3d9 748/*************************************************
7be682ca
PP
749* Expand key and cert file specs *
750*************************************************/
751
f5d78688 752/* Called once during tls_init and possibly again during TLS setup, for a
7be682ca
PP
753new context, if Server Name Indication was used and tls_sni was seen in
754the certificate string.
755
756Arguments:
757 sctx the SSL_CTX* to update
758 cbinfo various parts of session state
759
760Returns: OK/DEFER/FAIL
761*/
762
763static int
3f7eeb86 764tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
7be682ca
PP
765{
766uschar *expanded;
767
768if (cbinfo->certificate == NULL)
769 return OK;
770
d9b2312b
JH
771if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
772 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
773 Ustrstr(cbinfo->certificate, US"tls_out_sni")
774 )
7be682ca
PP
775 reexpand_tls_files_for_sni = TRUE;
776
777if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
778 return DEFER;
779
780if (expanded != NULL)
781 {
782 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
783 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
784 return tls_error(string_sprintf(
785 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
786 cbinfo->host, NULL);
787 }
788
789if (cbinfo->privatekey != NULL &&
790 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
791 return DEFER;
792
793/* If expansion was forced to fail, key_expanded will be NULL. If the result
794of the expansion is an empty string, ignore it also, and assume the private
795key is in the same file as the certificate. */
796
797if (expanded != NULL && *expanded != 0)
798 {
799 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
800 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
801 return tls_error(string_sprintf(
802 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
803 }
804
f2de3a33 805#ifndef DISABLE_OCSP
f5d78688 806if (cbinfo->is_server && cbinfo->u_ocsp.server.file != NULL)
3f7eeb86 807 {
f5d78688 808 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded))
3f7eeb86
PP
809 return DEFER;
810
811 if (expanded != NULL && *expanded != 0)
812 {
813 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
f5d78688
JH
814 if (cbinfo->u_ocsp.server.file_expanded &&
815 (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
3f7eeb86
PP
816 {
817 DEBUG(D_tls)
818 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
819 } else {
820 ocsp_load_response(sctx, cbinfo, expanded);
821 }
822 }
823 }
824#endif
825
7be682ca
PP
826return OK;
827}
828
829
830
831
832/*************************************************
833* Callback to handle SNI *
834*************************************************/
835
836/* Called when acting as server during the TLS session setup if a Server Name
837Indication extension was sent by the client.
838
839API documentation is OpenSSL s_server.c implementation.
840
841Arguments:
842 s SSL* of the current session
843 ad unknown (part of OpenSSL API) (unused)
844 arg Callback of "our" registered data
845
846Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
847*/
848
3bcbbbe2 849#ifdef EXIM_HAVE_OPENSSL_TLSEXT
7be682ca 850static int
7be682ca
PP
851tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
852{
853const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
3f7eeb86 854tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
7be682ca 855int rc;
3f0945ff 856int old_pool = store_pool;
7be682ca
PP
857
858if (!servername)
859 return SSL_TLSEXT_ERR_OK;
860
3f0945ff 861DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
7be682ca
PP
862 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
863
864/* Make the extension value available for expansion */
3f0945ff 865store_pool = POOL_PERM;
817d9f57 866tls_in.sni = string_copy(US servername);
3f0945ff 867store_pool = old_pool;
7be682ca
PP
868
869if (!reexpand_tls_files_for_sni)
870 return SSL_TLSEXT_ERR_OK;
871
872/* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
873not confident that memcpy wouldn't break some internal reference counting.
874Especially since there's a references struct member, which would be off. */
875
0df4ab80 876if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
7be682ca
PP
877 {
878 ERR_error_string(ERR_get_error(), ssl_errstring);
879 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
880 return SSL_TLSEXT_ERR_NOACK;
881 }
882
883/* Not sure how many of these are actually needed, since SSL object
884already exists. Might even need this selfsame callback, for reneg? */
885
817d9f57
JH
886SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
887SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
888SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
889SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
890SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
891SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
7be682ca 892if (cbinfo->server_cipher_list)
817d9f57 893 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
f2de3a33 894#ifndef DISABLE_OCSP
f5d78688 895if (cbinfo->u_ocsp.server.file)
3f7eeb86 896 {
f5d78688 897 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
14c7b357 898 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
3f7eeb86
PP
899 }
900#endif
7be682ca 901
983207c1 902rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, verify_callback_server);
7be682ca
PP
903if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
904
3f7eeb86
PP
905/* do this after setup_certs, because this can require the certs for verifying
906OCSP information. */
817d9f57 907rc = tls_expand_session_files(server_sni, cbinfo);
7be682ca
PP
908if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
909
0df4ab80
JH
910if (!init_dh(server_sni, cbinfo->dhparam, NULL))
911 return SSL_TLSEXT_ERR_NOACK;
a799883d 912
7be682ca 913DEBUG(D_tls) debug_printf("Switching SSL context.\n");
817d9f57 914SSL_set_SSL_CTX(s, server_sni);
7be682ca
PP
915
916return SSL_TLSEXT_ERR_OK;
917}
3bcbbbe2 918#endif /* EXIM_HAVE_OPENSSL_TLSEXT */
7be682ca
PP
919
920
921
922
f2de3a33 923#ifndef DISABLE_OCSP
f5d78688 924
3f7eeb86
PP
925/*************************************************
926* Callback to handle OCSP Stapling *
927*************************************************/
928
929/* Called when acting as server during the TLS session setup if the client
930requests OCSP information with a Certificate Status Request.
931
932Documentation via openssl s_server.c and the Apache patch from the OpenSSL
933project.
934
935*/
936
937static int
f5d78688 938tls_server_stapling_cb(SSL *s, void *arg)
3f7eeb86
PP
939{
940const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
941uschar *response_der;
942int response_der_len;
943
af4a1bca
JH
944DEBUG(D_tls)
945 debug_printf("Received TLS status request (OCSP stapling); %s response.",
f5d78688
JH
946 cbinfo->u_ocsp.server.response ? "have" : "lack");
947
44662487 948tls_in.ocsp = OCSP_NOT_RESP;
f5d78688 949if (!cbinfo->u_ocsp.server.response)
3f7eeb86
PP
950 return SSL_TLSEXT_ERR_NOACK;
951
952response_der = NULL;
44662487
JH
953response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response,
954 &response_der);
3f7eeb86
PP
955if (response_der_len <= 0)
956 return SSL_TLSEXT_ERR_NOACK;
957
5e55c7a9 958SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
44662487 959tls_in.ocsp = OCSP_VFIED;
3f7eeb86
PP
960return SSL_TLSEXT_ERR_OK;
961}
962
3f7eeb86 963
f5d78688
JH
964static void
965time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
966{
967BIO_printf(bp, "\t%s: ", str);
968ASN1_GENERALIZEDTIME_print(bp, time);
969BIO_puts(bp, "\n");
970}
971
972static int
973tls_client_stapling_cb(SSL *s, void *arg)
974{
975tls_ext_ctx_cb * cbinfo = arg;
976const unsigned char * p;
977int len;
978OCSP_RESPONSE * rsp;
979OCSP_BASICRESP * bs;
980int i;
981
982DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
983len = SSL_get_tlsext_status_ocsp_resp(s, &p);
984if(!p)
985 {
44662487
JH
986 /* Expect this when we requested ocsp but got none */
987 if ( cbinfo->u_ocsp.client.verify_required
988 && log_extra_selector & LX_tls_cipher)
989 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
f5d78688
JH
990 else
991 DEBUG(D_tls) debug_printf(" null\n");
44662487 992 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
f5d78688 993 }
018058b2 994
f5d78688
JH
995if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
996 {
018058b2 997 tls_out.ocsp = OCSP_FAILED;
f5d78688 998 if (log_extra_selector & LX_tls_cipher)
1eca31ca 999 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
f5d78688
JH
1000 else
1001 DEBUG(D_tls) debug_printf(" parse error\n");
1002 return 0;
1003 }
1004
1005if(!(bs = OCSP_response_get1_basic(rsp)))
1006 {
018058b2 1007 tls_out.ocsp = OCSP_FAILED;
f5d78688 1008 if (log_extra_selector & LX_tls_cipher)
1eca31ca 1009 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
f5d78688
JH
1010 else
1011 DEBUG(D_tls) debug_printf(" error parsing response\n");
1012 OCSP_RESPONSE_free(rsp);
1013 return 0;
1014 }
1015
1016/* We'd check the nonce here if we'd put one in the request. */
1017/* However that would defeat cacheability on the server so we don't. */
1018
f5d78688
JH
1019/* This section of code reworked from OpenSSL apps source;
1020 The OpenSSL Project retains copyright:
1021 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1022*/
1023 {
1024 BIO * bp = NULL;
f5d78688
JH
1025 int status, reason;
1026 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1027
1028 DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE);
1029
1030 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1031
1032 /* Use the chain that verified the server cert to verify the stapled info */
1033 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1034
44662487
JH
1035 if ((i = OCSP_basic_verify(bs, NULL,
1036 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
f5d78688 1037 {
018058b2 1038 tls_out.ocsp = OCSP_FAILED;
1eca31ca
JH
1039 if (log_extra_selector & LX_tls_cipher)
1040 log_write(0, LOG_MAIN, "Received TLS cert status response, itself unverifiable");
f5d78688
JH
1041 BIO_printf(bp, "OCSP response verify failure\n");
1042 ERR_print_errors(bp);
44662487 1043 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
f5d78688
JH
1044 goto out;
1045 }
1046
1047 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1048
1049 {
1050 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1051 OCSP_SINGLERESP * single;
1052
1053 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1054 {
018058b2 1055 tls_out.ocsp = OCSP_FAILED;
44662487
JH
1056 log_write(0, LOG_MAIN, "OCSP stapling "
1057 "with multiple responses not handled");
1058 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
f5d78688
JH
1059 goto out;
1060 }
1061 single = OCSP_resp_get0(bs, 0);
44662487
JH
1062 status = OCSP_single_get0_status(single, &reason, &rev,
1063 &thisupd, &nextupd);
f5d78688
JH
1064 }
1065
f5d78688
JH
1066 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1067 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
44662487
JH
1068 if (!OCSP_check_validity(thisupd, nextupd,
1069 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
f5d78688 1070 {
018058b2 1071 tls_out.ocsp = OCSP_FAILED;
f5d78688
JH
1072 DEBUG(D_tls) ERR_print_errors(bp);
1073 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
44662487 1074 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
f5d78688 1075 }
44662487 1076 else
f5d78688 1077 {
44662487
JH
1078 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1079 OCSP_cert_status_str(status));
1080 switch(status)
1081 {
1082 case V_OCSP_CERTSTATUS_GOOD:
44662487 1083 tls_out.ocsp = OCSP_VFIED;
018058b2 1084 i = 1;
44662487
JH
1085 break;
1086 case V_OCSP_CERTSTATUS_REVOKED:
018058b2 1087 tls_out.ocsp = OCSP_FAILED;
44662487
JH
1088 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1089 reason != -1 ? "; reason: " : "",
1090 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1091 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1092 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1093 break;
1094 default:
018058b2 1095 tls_out.ocsp = OCSP_FAILED;
44662487
JH
1096 log_write(0, LOG_MAIN,
1097 "Server certificate status unknown, in OCSP stapling");
1098 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1099 break;
1100 }
f5d78688
JH
1101 }
1102 out:
1103 BIO_free(bp);
1104 }
1105
1106OCSP_RESPONSE_free(rsp);
1107return i;
1108}
f2de3a33 1109#endif /*!DISABLE_OCSP*/
3f7eeb86
PP
1110
1111
7be682ca 1112/*************************************************
059ec3d9
PH
1113* Initialize for TLS *
1114*************************************************/
1115
e51c7be2
JH
1116/* Called from both server and client code, to do preliminary initialization
1117of the library. We allocate and return a context structure.
059ec3d9
PH
1118
1119Arguments:
946ecbe0 1120 ctxp returned SSL context
059ec3d9
PH
1121 host connected host, if client; NULL if server
1122 dhparam DH parameter file
1123 certificate certificate file
1124 privatekey private key
f5d78688 1125 ocsp_file file of stapling info (server); flag for require ocsp (client)
059ec3d9 1126 addr address if client; NULL if server (for some randomness)
946ecbe0 1127 cbp place to put allocated callback context
059ec3d9
PH
1128
1129Returns: OK/DEFER/FAIL
1130*/
1131
1132static int
817d9f57 1133tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
3f7eeb86 1134 uschar *privatekey,
f2de3a33 1135#ifndef DISABLE_OCSP
3f7eeb86
PP
1136 uschar *ocsp_file,
1137#endif
817d9f57 1138 address_item *addr, tls_ext_ctx_cb ** cbp)
059ec3d9 1139{
77bb000f 1140long init_options;
7be682ca 1141int rc;
77bb000f 1142BOOL okay;
a7538db1 1143tls_ext_ctx_cb * cbinfo;
7be682ca
PP
1144
1145cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1146cbinfo->certificate = certificate;
1147cbinfo->privatekey = privatekey;
f2de3a33 1148#ifndef DISABLE_OCSP
f5d78688
JH
1149if ((cbinfo->is_server = host==NULL))
1150 {
1151 cbinfo->u_ocsp.server.file = ocsp_file;
1152 cbinfo->u_ocsp.server.file_expanded = NULL;
1153 cbinfo->u_ocsp.server.response = NULL;
1154 }
1155else
1156 cbinfo->u_ocsp.client.verify_store = NULL;
3f7eeb86 1157#endif
7be682ca 1158cbinfo->dhparam = dhparam;
0df4ab80 1159cbinfo->server_cipher_list = NULL;
7be682ca 1160cbinfo->host = host;
774ef2d7 1161#ifdef EXPERIMENTAL_EVENT
a7538db1
JH
1162cbinfo->event_action = NULL;
1163#endif
77bb000f 1164
059ec3d9
PH
1165SSL_load_error_strings(); /* basic set up */
1166OpenSSL_add_ssl_algorithms();
1167
388d6564 1168#if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
77bb000f 1169/* SHA256 is becoming ever more popular. This makes sure it gets added to the
a0475b69
TK
1170list of available digests. */
1171EVP_add_digest(EVP_sha256());
cf1ef1a9 1172#endif
a0475b69 1173
f0f5a555
PP
1174/* Create a context.
1175The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1176negotiation in the different methods; as far as I can tell, the only
1177*_{server,client}_method which allows negotiation is SSLv23, which exists even
1178when OpenSSL is built without SSLv2 support.
1179By disabling with openssl_options, we can let admins re-enable with the
1180existing knob. */
059ec3d9 1181
817d9f57 1182*ctxp = SSL_CTX_new((host == NULL)?
059ec3d9
PH
1183 SSLv23_server_method() : SSLv23_client_method());
1184
817d9f57 1185if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
059ec3d9
PH
1186
1187/* It turns out that we need to seed the random number generator this early in
1188order to get the full complement of ciphers to work. It took me roughly a day
1189of work to discover this by experiment.
1190
1191On systems that have /dev/urandom, SSL may automatically seed itself from
1192there. Otherwise, we have to make something up as best we can. Double check
1193afterwards. */
1194
1195if (!RAND_status())
1196 {
1197 randstuff r;
9e3331ea 1198 gettimeofday(&r.tv, NULL);
059ec3d9
PH
1199 r.p = getpid();
1200
1201 RAND_seed((uschar *)(&r), sizeof(r));
1202 RAND_seed((uschar *)big_buffer, big_buffer_size);
1203 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
1204
1205 if (!RAND_status())
7199e1ee 1206 return tls_error(US"RAND_status", host,
5ca6d115 1207 US"unable to seed random number generator");
059ec3d9
PH
1208 }
1209
1210/* Set up the information callback, which outputs if debugging is at a suitable
1211level. */
1212
817d9f57 1213SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback);
059ec3d9 1214
c80c5570 1215/* Automatically re-try reads/writes after renegotiation. */
817d9f57 1216(void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY);
c80c5570 1217
77bb000f
PP
1218/* Apply administrator-supplied work-arounds.
1219Historically we applied just one requested option,
1220SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1221moved to an administrator-controlled list of options to specify and
1222grandfathered in the first one as the default value for "openssl_options".
059ec3d9 1223
77bb000f
PP
1224No OpenSSL version number checks: the options we accept depend upon the
1225availability of the option value macros from OpenSSL. */
059ec3d9 1226
77bb000f
PP
1227okay = tls_openssl_options_parse(openssl_options, &init_options);
1228if (!okay)
73a46702 1229 return tls_error(US"openssl_options parsing failed", host, NULL);
77bb000f
PP
1230
1231if (init_options)
1232 {
1233 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
817d9f57 1234 if (!(SSL_CTX_set_options(*ctxp, init_options)))
77bb000f
PP
1235 return tls_error(string_sprintf(
1236 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
1237 }
1238else
1239 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
059ec3d9
PH
1240
1241/* Initialize with DH parameters if supplied */
1242
817d9f57 1243if (!init_dh(*ctxp, dhparam, host)) return DEFER;
059ec3d9 1244
3f7eeb86 1245/* Set up certificate and key (and perhaps OCSP info) */
059ec3d9 1246
817d9f57 1247rc = tls_expand_session_files(*ctxp, cbinfo);
7be682ca 1248if (rc != OK) return rc;
c91535f3 1249
7be682ca 1250/* If we need to handle SNI, do so */
3bcbbbe2 1251#ifdef EXIM_HAVE_OPENSSL_TLSEXT
f5d78688 1252if (host == NULL) /* server */
3f0945ff 1253 {
f2de3a33 1254# ifndef DISABLE_OCSP
f5d78688 1255 /* We check u_ocsp.server.file, not server.response, because we care about if
3f7eeb86
PP
1256 the option exists, not what the current expansion might be, as SNI might
1257 change the certificate and OCSP file in use between now and the time the
1258 callback is invoked. */
f5d78688 1259 if (cbinfo->u_ocsp.server.file)
3f7eeb86 1260 {
f5d78688 1261 SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb);
5e55c7a9 1262 SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo);
3f7eeb86 1263 }
f5d78688 1264# endif
3f0945ff
PP
1265 /* We always do this, so that $tls_sni is available even if not used in
1266 tls_certificate */
817d9f57
JH
1267 SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb);
1268 SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo);
3f0945ff 1269 }
f2de3a33 1270# ifndef DISABLE_OCSP
f5d78688
JH
1271else /* client */
1272 if(ocsp_file) /* wanting stapling */
1273 {
1274 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1275 {
1276 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1277 return FAIL;
1278 }
1279 SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb);
1280 SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo);
1281 }
1282# endif
7be682ca 1283#endif
059ec3d9 1284
e51c7be2 1285cbinfo->verify_cert_hostnames = NULL;
e51c7be2 1286
059ec3d9
PH
1287/* Set up the RSA callback */
1288
817d9f57 1289SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback);
059ec3d9
PH
1290
1291/* Finally, set the timeout, and we are done */
1292
817d9f57 1293SSL_CTX_set_timeout(*ctxp, ssl_session_timeout);
059ec3d9 1294DEBUG(D_tls) debug_printf("Initialized TLS\n");
7be682ca 1295
817d9f57 1296*cbp = cbinfo;
7be682ca 1297
059ec3d9
PH
1298return OK;
1299}
1300
1301
1302
1303
1304/*************************************************
1305* Get name of cipher in use *
1306*************************************************/
1307
817d9f57 1308/*
059ec3d9 1309Argument: pointer to an SSL structure for the connection
817d9f57
JH
1310 buffer to use for answer
1311 size of buffer
1312 pointer to number of bits for cipher
059ec3d9
PH
1313Returns: nothing
1314*/
1315
1316static void
817d9f57 1317construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
059ec3d9 1318{
57b3a7f5
PP
1319/* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1320yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1321the accessor functions use const in the prototype. */
1322const SSL_CIPHER *c;
d9784128 1323const uschar *ver;
059ec3d9 1324
d9784128 1325ver = (const uschar *)SSL_get_version(ssl);
059ec3d9 1326
57b3a7f5 1327c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
817d9f57 1328SSL_CIPHER_get_bits(c, bits);
059ec3d9 1329
817d9f57
JH
1330string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1331 SSL_CIPHER_get_name(c), *bits);
059ec3d9
PH
1332
1333DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1334}
1335
1336
1337
1338
1339
1340/*************************************************
1341* Set up for verifying certificates *
1342*************************************************/
1343
1344/* Called by both client and server startup
1345
1346Arguments:
7be682ca 1347 sctx SSL_CTX* to initialise
059ec3d9
PH
1348 certs certs file or NULL
1349 crl CRL file or NULL
1350 host NULL in a server; the remote host in a client
1351 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1352 otherwise passed as FALSE
983207c1 1353 cert_vfy_cb Callback function for certificate verification
059ec3d9
PH
1354
1355Returns: OK/DEFER/FAIL
1356*/
1357
1358static int
983207c1
JH
1359setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1360 int (*cert_vfy_cb)(int, X509_STORE_CTX *) )
059ec3d9
PH
1361{
1362uschar *expcerts, *expcrl;
1363
1364if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
1365 return DEFER;
1366
26e72755 1367if (expcerts != NULL && *expcerts != '\0')
059ec3d9
PH
1368 {
1369 struct stat statbuf;
7be682ca 1370 if (!SSL_CTX_set_default_verify_paths(sctx))
7199e1ee 1371 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
059ec3d9
PH
1372
1373 if (Ustat(expcerts, &statbuf) < 0)
1374 {
1375 log_write(0, LOG_MAIN|LOG_PANIC,
1376 "failed to stat %s for certificates", expcerts);
1377 return DEFER;
1378 }
1379 else
1380 {
1381 uschar *file, *dir;
1382 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1383 { file = NULL; dir = expcerts; }
1384 else
1385 { file = expcerts; dir = NULL; }
1386
1387 /* If a certificate file is empty, the next function fails with an
1388 unhelpful error message. If we skip it, we get the correct behaviour (no
1389 certificates are recognized, but the error message is still misleading (it
1390 says no certificate was supplied.) But this is better. */
1391
1392 if ((file == NULL || statbuf.st_size > 0) &&
7be682ca 1393 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
7199e1ee 1394 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
059ec3d9 1395
3281c6ea 1396 /* Load the list of CAs for which we will accept certs, for sending
a805c12a
JH
1397 to the client. This is only for the one-file tls_verify_certificates
1398 variant.
1399 If a list isn't loaded into the server, but
1400 some verify locations are set, the server end appears to make
1401 a wildcard reqest for client certs.
1402 Meanwhile, the client library as deafult behaviour *ignores* the list
1403 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1404 Because of this, and that the dir variant is likely only used for
1405 the public-CA bundle (not for a private CA), not worth fixing.
1406 */
059ec3d9
PH
1407 if (file != NULL)
1408 {
3281c6ea
JH
1409 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
1410DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
1411 sk_X509_NAME_num(names));
1412 SSL_CTX_set_client_CA_list(sctx, names);
059ec3d9
PH
1413 }
1414 }
1415
1416 /* Handle a certificate revocation list. */
1417
1418 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1419
8b417f2c
PH
1420 /* This bit of code is now the version supplied by Lars Mainka. (I have
1421 * merely reformatted it into the Exim code style.)
1422
1423 * "From here I changed the code to add support for multiple crl's
1424 * in pem format in one file or to support hashed directory entries in
1425 * pem format instead of a file. This method now uses the library function
1426 * X509_STORE_load_locations to add the CRL location to the SSL context.
1427 * OpenSSL will then handle the verify against CA certs and CRLs by
1428 * itself in the verify callback." */
1429
059ec3d9
PH
1430 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1431 if (expcrl != NULL && *expcrl != 0)
1432 {
8b417f2c
PH
1433 struct stat statbufcrl;
1434 if (Ustat(expcrl, &statbufcrl) < 0)
1435 {
1436 log_write(0, LOG_MAIN|LOG_PANIC,
1437 "failed to stat %s for certificates revocation lists", expcrl);
1438 return DEFER;
1439 }
1440 else
059ec3d9 1441 {
8b417f2c
PH
1442 /* is it a file or directory? */
1443 uschar *file, *dir;
7be682ca 1444 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
8b417f2c 1445 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
059ec3d9 1446 {
8b417f2c
PH
1447 file = NULL;
1448 dir = expcrl;
1449 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
059ec3d9
PH
1450 }
1451 else
1452 {
8b417f2c
PH
1453 file = expcrl;
1454 dir = NULL;
1455 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
059ec3d9 1456 }
8b417f2c 1457 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
7199e1ee 1458 return tls_error(US"X509_STORE_load_locations", host, NULL);
8b417f2c
PH
1459
1460 /* setting the flags to check against the complete crl chain */
1461
1462 X509_STORE_set_flags(cvstore,
1463 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
059ec3d9 1464 }
059ec3d9
PH
1465 }
1466
1467 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1468
1469 /* If verification is optional, don't fail if no certificate */
1470
7be682ca 1471 SSL_CTX_set_verify(sctx,
059ec3d9 1472 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
983207c1 1473 cert_vfy_cb);
059ec3d9
PH
1474 }
1475
1476return OK;
1477}
1478
1479
1480
1481/*************************************************
1482* Start a TLS session in a server *
1483*************************************************/
1484
1485/* This is called when Exim is running as a server, after having received
1486the STARTTLS command. It must respond to that command, and then negotiate
1487a TLS session.
1488
1489Arguments:
1490 require_ciphers allowed ciphers
1491
1492Returns: OK on success
1493 DEFER for errors before the start of the negotiation
1494 FAIL for errors during the negotation; the server can't
1495 continue running.
1496*/
1497
1498int
17c76198 1499tls_server_start(const uschar *require_ciphers)
059ec3d9
PH
1500{
1501int rc;
1502uschar *expciphers;
7be682ca 1503tls_ext_ctx_cb *cbinfo;
817d9f57 1504static uschar cipherbuf[256];
059ec3d9
PH
1505
1506/* Check for previous activation */
1507
817d9f57 1508if (tls_in.active >= 0)
059ec3d9 1509 {
5ca6d115 1510 tls_error(US"STARTTLS received after TLS started", NULL, US"");
059ec3d9
PH
1511 smtp_printf("554 Already in TLS\r\n");
1512 return FAIL;
1513 }
1514
1515/* Initialize the SSL library. If it fails, it will already have logged
1516the error. */
1517
817d9f57 1518rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
f2de3a33 1519#ifndef DISABLE_OCSP
3f7eeb86
PP
1520 tls_ocsp_file,
1521#endif
817d9f57 1522 NULL, &server_static_cbinfo);
059ec3d9 1523if (rc != OK) return rc;
817d9f57 1524cbinfo = server_static_cbinfo;
059ec3d9
PH
1525
1526if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1527 return FAIL;
1528
1529/* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
17c76198
PP
1530were historically separated by underscores. So that I can use either form in my
1531tests, and also for general convenience, we turn underscores into hyphens here.
1532*/
059ec3d9
PH
1533
1534if (expciphers != NULL)
1535 {
1536 uschar *s = expciphers;
1537 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1538 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
817d9f57 1539 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
7199e1ee 1540 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
7be682ca 1541 cbinfo->server_cipher_list = expciphers;
059ec3d9
PH
1542 }
1543
1544/* If this is a host for which certificate verification is mandatory or
1545optional, set up appropriately. */
1546
817d9f57 1547tls_in.certificate_verified = FALSE;
53a7196b
JH
1548#ifdef EXPERIMENTAL_DANE
1549tls_in.dane_verified = FALSE;
1550#endif
a2ff477a 1551server_verify_callback_called = FALSE;
059ec3d9
PH
1552
1553if (verify_check_host(&tls_verify_hosts) == OK)
1554 {
983207c1
JH
1555 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1556 FALSE, verify_callback_server);
059ec3d9 1557 if (rc != OK) return rc;
a2ff477a 1558 server_verify_optional = FALSE;
059ec3d9
PH
1559 }
1560else if (verify_check_host(&tls_try_verify_hosts) == OK)
1561 {
983207c1
JH
1562 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1563 TRUE, verify_callback_server);
059ec3d9 1564 if (rc != OK) return rc;
a2ff477a 1565 server_verify_optional = TRUE;
059ec3d9
PH
1566 }
1567
1568/* Prepare for new connection */
1569
817d9f57 1570if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
da3ad30d
PP
1571
1572/* Warning: we used to SSL_clear(ssl) here, it was removed.
1573 *
1574 * With the SSL_clear(), we get strange interoperability bugs with
1575 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1576 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1577 *
1578 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1579 * session shutdown. In this case, we have a brand new object and there's no
1580 * obvious reason to immediately clear it. I'm guessing that this was
1581 * originally added because of incomplete initialisation which the clear fixed,
1582 * in some historic release.
1583 */
059ec3d9
PH
1584
1585/* Set context and tell client to go ahead, except in the case of TLS startup
1586on connection, where outputting anything now upsets the clients and tends to
1587make them disconnect. We need to have an explicit fflush() here, to force out
1588the response. Other smtp_printf() calls do not need it, because in non-TLS
1589mode, the fflush() happens when smtp_getc() is called. */
1590
817d9f57
JH
1591SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1592if (!tls_in.on_connect)
059ec3d9
PH
1593 {
1594 smtp_printf("220 TLS go ahead\r\n");
1595 fflush(smtp_out);
1596 }
1597
1598/* Now negotiate the TLS session. We put our own timer on it, since it seems
1599that the OpenSSL library doesn't. */
1600
817d9f57
JH
1601SSL_set_wfd(server_ssl, fileno(smtp_out));
1602SSL_set_rfd(server_ssl, fileno(smtp_in));
1603SSL_set_accept_state(server_ssl);
059ec3d9
PH
1604
1605DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1606
1607sigalrm_seen = FALSE;
1608if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
817d9f57 1609rc = SSL_accept(server_ssl);
059ec3d9
PH
1610alarm(0);
1611
1612if (rc <= 0)
1613 {
7199e1ee 1614 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
77bb000f
PP
1615 if (ERR_get_error() == 0)
1616 log_write(0, LOG_MAIN,
a053d125 1617 "TLS client disconnected cleanly (rejected our certificate?)");
059ec3d9
PH
1618 return FAIL;
1619 }
1620
1621DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1622
1623/* TLS has been set up. Adjust the input functions to read via TLS,
1624and initialize things. */
1625
817d9f57
JH
1626construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1627tls_in.cipher = cipherbuf;
059ec3d9
PH
1628
1629DEBUG(D_tls)
1630 {
1631 uschar buf[2048];
817d9f57 1632 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
059ec3d9
PH
1633 debug_printf("Shared ciphers: %s\n", buf);
1634 }
1635
9d1c15ef
JH
1636/* Record the certificate we presented */
1637 {
1638 X509 * crt = SSL_get_certificate(server_ssl);
1639 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
1640 }
059ec3d9 1641
817d9f57
JH
1642/* Only used by the server-side tls (tls_in), including tls_getc.
1643 Client-side (tls_out) reads (seem to?) go via
1644 smtp_read_response()/ip_recv().
1645 Hence no need to duplicate for _in and _out.
1646 */
059ec3d9
PH
1647ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1648ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1649ssl_xfer_eof = ssl_xfer_error = 0;
1650
1651receive_getc = tls_getc;
1652receive_ungetc = tls_ungetc;
1653receive_feof = tls_feof;
1654receive_ferror = tls_ferror;
58eb016e 1655receive_smtp_buffered = tls_smtp_buffered;
059ec3d9 1656
817d9f57 1657tls_in.active = fileno(smtp_out);
059ec3d9
PH
1658return OK;
1659}
1660
1661
1662
1663
043b1248
JH
1664static int
1665tls_client_basic_ctx_init(SSL_CTX * ctx,
01a4a5c5 1666 host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo
043b1248
JH
1667 )
1668{
1669int rc;
1670/* stick to the old behaviour for compatibility if tls_verify_certificates is
1671 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
1672 the specified host patterns if one of them is defined */
1673
aa2a70ba 1674if ( (!ob->tls_verify_hosts && !ob->tls_try_verify_hosts)
5130845b 1675 || (verify_check_given_host(&ob->tls_verify_hosts, host) == OK)
aa2a70ba 1676 )
043b1248 1677 client_verify_optional = FALSE;
5130845b 1678else if (verify_check_given_host(&ob->tls_try_verify_hosts, host) == OK)
aa2a70ba
JH
1679 client_verify_optional = TRUE;
1680else
1681 return OK;
1682
1683if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1684 ob->tls_crl, host, client_verify_optional, verify_callback_client)) != OK)
1685 return rc;
043b1248 1686
5130845b 1687if (verify_check_given_host(&ob->tls_verify_cert_hostnames, host) == OK)
043b1248 1688 {
aa2a70ba
JH
1689 cbinfo->verify_cert_hostnames = host->name;
1690 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
1691 cbinfo->verify_cert_hostnames);
043b1248 1692 }
043b1248
JH
1693return OK;
1694}
059ec3d9 1695
fde080a4
JH
1696
1697#ifdef EXPERIMENTAL_DANE
1698static int
fde080a4
JH
1699dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa)
1700{
1701dns_record * rr;
1702dns_scan dnss;
1703const char * hostnames[2] = { CS host->name, NULL };
1704int found = 0;
1705
1706if (DANESSL_init(ssl, NULL, hostnames) != 1)
1707 return tls_error(US"hostnames load", host, NULL);
1708
1709for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
1710 rr;
1711 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
1712 ) if (rr->type == T_TLSA)
1713 {
1714 uschar * p = rr->data;
1715 uint8_t usage, selector, mtype;
1716 const char * mdname;
1717
fde080a4 1718 usage = *p++;
133d2546
JH
1719
1720 /* Only DANE-TA(2) and DANE-EE(3) are supported */
1721 if (usage != 2 && usage != 3) continue;
1722
fde080a4
JH
1723 selector = *p++;
1724 mtype = *p++;
1725
1726 switch (mtype)
1727 {
133d2546
JH
1728 default: continue; /* Only match-types 0, 1, 2 are supported */
1729 case 0: mdname = NULL; break;
1730 case 1: mdname = "sha256"; break;
1731 case 2: mdname = "sha512"; break;
fde080a4
JH
1732 }
1733
133d2546 1734 found++;
fde080a4
JH
1735 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
1736 {
1737 default:
1738 case 0: /* action not taken */
1739 return tls_error(US"tlsa load", host, NULL);
1740 case 1: break;
1741 }
594706ea
JH
1742
1743 tls_out.tlsa_usage |= 1<<usage;
fde080a4
JH
1744 }
1745
1746if (found)
1747 return OK;
1748
133d2546 1749log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
fde080a4
JH
1750return FAIL;
1751}
1752#endif /*EXPERIMENTAL_DANE*/
1753
1754
1755
059ec3d9
PH
1756/*************************************************
1757* Start a TLS session in a client *
1758*************************************************/
1759
1760/* Called from the smtp transport after STARTTLS has been accepted.
1761
1762Argument:
1763 fd the fd of the connection
1764 host connected host (for messages)
83da1223 1765 addr the first address
a7538db1 1766 tb transport (always smtp)
0e66b3b6 1767 tlsa_dnsa tlsa lookup, if DANE, else null
059ec3d9
PH
1768
1769Returns: OK on success
1770 FAIL otherwise - note that tls_error() will not give DEFER
1771 because this is not a server
1772*/
1773
1774int
f5d78688 1775tls_client_start(int fd, host_item *host, address_item *addr,
0e66b3b6
JH
1776 transport_instance *tb
1777#ifdef EXPERIMENTAL_DANE
1778 , dns_answer * tlsa_dnsa
1779#endif
1780 )
059ec3d9 1781{
a7538db1
JH
1782smtp_transport_options_block * ob =
1783 (smtp_transport_options_block *)tb->options_block;
059ec3d9 1784static uschar txt[256];
868f5672
JH
1785uschar * expciphers;
1786X509 * server_cert;
059ec3d9 1787int rc;
817d9f57 1788static uschar cipherbuf[256];
043b1248
JH
1789
1790#ifndef DISABLE_OCSP
043b1248 1791BOOL request_ocsp = FALSE;
6634ac8d 1792BOOL require_ocsp = FALSE;
043b1248 1793#endif
043b1248
JH
1794
1795#ifdef EXPERIMENTAL_DANE
594706ea 1796tls_out.tlsa_usage = 0;
043b1248
JH
1797#endif
1798
f2de3a33 1799#ifndef DISABLE_OCSP
043b1248 1800 {
4f59c424
JH
1801# ifdef EXPERIMENTAL_DANE
1802 if ( tlsa_dnsa
1803 && ob->hosts_request_ocsp[0] == '*'
1804 && ob->hosts_request_ocsp[1] == '\0'
1805 )
1806 {
1807 /* Unchanged from default. Use a safer one under DANE */
1808 request_ocsp = TRUE;
1809 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
1810 " {= {4}{$tls_out_tlsa_usage}} } "
1811 " {*}{}}";
1812 }
1813# endif
1814
5130845b
JH
1815 if ((require_ocsp =
1816 verify_check_given_host(&ob->hosts_require_ocsp, host) == OK))
fca41d5a
JH
1817 request_ocsp = TRUE;
1818 else
fca41d5a 1819# ifdef EXPERIMENTAL_DANE
4f59c424 1820 if (!request_ocsp)
fca41d5a 1821# endif
5130845b
JH
1822 request_ocsp =
1823 verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
043b1248 1824 }
f5d78688 1825#endif
059ec3d9 1826
65867078
JH
1827rc = tls_init(&client_ctx, host, NULL,
1828 ob->tls_certificate, ob->tls_privatekey,
f2de3a33 1829#ifndef DISABLE_OCSP
44662487 1830 (void *)(long)request_ocsp,
3f7eeb86 1831#endif
817d9f57 1832 addr, &client_static_cbinfo);
059ec3d9
PH
1833if (rc != OK) return rc;
1834
817d9f57 1835tls_out.certificate_verified = FALSE;
a2ff477a 1836client_verify_callback_called = FALSE;
059ec3d9 1837
65867078
JH
1838if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
1839 &expciphers))
059ec3d9
PH
1840 return FAIL;
1841
1842/* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1843are separated by underscores. So that I can use either form in my tests, and
1844also for general convenience, we turn underscores into hyphens here. */
1845
1846if (expciphers != NULL)
1847 {
1848 uschar *s = expciphers;
1849 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1850 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
817d9f57 1851 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
7199e1ee 1852 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
059ec3d9
PH
1853 }
1854
043b1248 1855#ifdef EXPERIMENTAL_DANE
0e66b3b6 1856if (tlsa_dnsa)
a63be306 1857 {
02af313d
JH
1858 SSL_CTX_set_verify(client_ctx,
1859 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
1860 verify_callback_client_dane);
e5cccda9 1861
043b1248 1862 if (!DANESSL_library_init())
b4161d10 1863 return tls_error(US"library init", host, NULL);
043b1248 1864 if (DANESSL_CTX_init(client_ctx) <= 0)
b4161d10 1865 return tls_error(US"context init", host, NULL);
043b1248
JH
1866 }
1867else
e51c7be2 1868
043b1248
JH
1869#endif
1870
01a4a5c5
JH
1871 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob, client_static_cbinfo))
1872 != OK)
65867078 1873 return rc;
059ec3d9 1874
65867078
JH
1875if ((client_ssl = SSL_new(client_ctx)) == NULL)
1876 return tls_error(US"SSL_new", host, NULL);
817d9f57
JH
1877SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
1878SSL_set_fd(client_ssl, fd);
1879SSL_set_connect_state(client_ssl);
059ec3d9 1880
65867078 1881if (ob->tls_sni)
3f0945ff 1882 {
65867078 1883 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni))
3f0945ff 1884 return FAIL;
ec4b68e5 1885 if (tls_out.sni == NULL)
2c9a0e86
PP
1886 {
1887 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
1888 }
ec4b68e5 1889 else if (!Ustrlen(tls_out.sni))
817d9f57 1890 tls_out.sni = NULL;
3f0945ff
PP
1891 else
1892 {
35731706 1893#ifdef EXIM_HAVE_OPENSSL_TLSEXT
817d9f57
JH
1894 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
1895 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
35731706
PP
1896#else
1897 DEBUG(D_tls)
1898 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
02d9264f 1899 tls_out.sni);
35731706 1900#endif
3f0945ff
PP
1901 }
1902 }
1903
594706ea 1904#ifdef EXPERIMENTAL_DANE
0e66b3b6
JH
1905if (tlsa_dnsa)
1906 if ((rc = dane_tlsa_load(client_ssl, host, tlsa_dnsa)) != OK)
594706ea
JH
1907 return rc;
1908#endif
1909
f2de3a33 1910#ifndef DISABLE_OCSP
f5d78688
JH
1911/* Request certificate status at connection-time. If the server
1912does OCSP stapling we will get the callback (set in tls_init()) */
b50c8b84 1913# ifdef EXPERIMENTAL_DANE
44662487
JH
1914if (request_ocsp)
1915 {
594706ea 1916 const uschar * s;
41afb5cb
JH
1917 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
1918 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
594706ea
JH
1919 )
1920 { /* Re-eval now $tls_out_tlsa_usage is populated. If
1921 this means we avoid the OCSP request, we wasted the setup
1922 cost in tls_init(). */
5130845b
JH
1923 require_ocsp = verify_check_given_host(&ob->hosts_require_ocsp, host) == OK;
1924 request_ocsp = require_ocsp
1925 || verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
594706ea
JH
1926 }
1927 }
b50c8b84
JH
1928# endif
1929
594706ea
JH
1930if (request_ocsp)
1931 {
f5d78688 1932 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
44662487
JH
1933 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
1934 tls_out.ocsp = OCSP_NOT_RESP;
1935 }
f5d78688
JH
1936#endif
1937
774ef2d7
JH
1938#ifdef EXPERIMENTAL_EVENT
1939client_static_cbinfo->event_action = tb->event_action;
a7538db1 1940#endif
043b1248 1941
059ec3d9
PH
1942/* There doesn't seem to be a built-in timeout on connection. */
1943
1944DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1945sigalrm_seen = FALSE;
65867078 1946alarm(ob->command_timeout);
817d9f57 1947rc = SSL_connect(client_ssl);
059ec3d9
PH
1948alarm(0);
1949
043b1248 1950#ifdef EXPERIMENTAL_DANE
0e66b3b6 1951if (tlsa_dnsa)
fde080a4 1952 DANESSL_cleanup(client_ssl);
043b1248
JH
1953#endif
1954
059ec3d9 1955if (rc <= 0)
7199e1ee 1956 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
059ec3d9
PH
1957
1958DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1959
453a6645 1960/* Beware anonymous ciphers which lead to server_cert being NULL */
9d1c15ef 1961/*XXX server_cert is never freed... use X509_free() */
817d9f57 1962server_cert = SSL_get_peer_certificate (client_ssl);
453a6645
PP
1963if (server_cert)
1964 {
817d9f57 1965 tls_out.peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
453a6645 1966 CS txt, sizeof(txt));
9d1c15ef 1967 tls_out.peerdn = txt; /*XXX a static buffer... */
453a6645
PP
1968 }
1969else
817d9f57 1970 tls_out.peerdn = NULL;
059ec3d9 1971
817d9f57
JH
1972construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
1973tls_out.cipher = cipherbuf;
059ec3d9 1974
9d1c15ef
JH
1975/* Record the certificate we presented */
1976 {
1977 X509 * crt = SSL_get_certificate(client_ssl);
1978 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
1979 }
1980
817d9f57 1981tls_out.active = fd;
059ec3d9
PH
1982return OK;
1983}
1984
1985
1986
1987
1988
1989/*************************************************
1990* TLS version of getc *
1991*************************************************/
1992
1993/* This gets the next byte from the TLS input buffer. If the buffer is empty,
1994it refills the buffer via the SSL reading function.
1995
1996Arguments: none
1997Returns: the next character or EOF
817d9f57
JH
1998
1999Only used by the server-side TLS.
059ec3d9
PH
2000*/
2001
2002int
2003tls_getc(void)
2004{
2005if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2006 {
2007 int error;
2008 int inbytes;
2009
817d9f57 2010 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
c80c5570 2011 ssl_xfer_buffer, ssl_xfer_buffer_size);
059ec3d9
PH
2012
2013 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
817d9f57
JH
2014 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
2015 error = SSL_get_error(server_ssl, inbytes);
059ec3d9
PH
2016 alarm(0);
2017
2018 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2019 closed down, not that the socket itself has been closed down. Revert to
2020 non-SSL handling. */
2021
2022 if (error == SSL_ERROR_ZERO_RETURN)
2023 {
2024 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2025
2026 receive_getc = smtp_getc;
2027 receive_ungetc = smtp_ungetc;
2028 receive_feof = smtp_feof;
2029 receive_ferror = smtp_ferror;
58eb016e 2030 receive_smtp_buffered = smtp_buffered;
059ec3d9 2031
817d9f57
JH
2032 SSL_free(server_ssl);
2033 server_ssl = NULL;
2034 tls_in.active = -1;
2035 tls_in.bits = 0;
2036 tls_in.cipher = NULL;
2037 tls_in.peerdn = NULL;
2038 tls_in.sni = NULL;
059ec3d9
PH
2039
2040 return smtp_getc();
2041 }
2042
2043 /* Handle genuine errors */
2044
ba084640
PP
2045 else if (error == SSL_ERROR_SSL)
2046 {
2047 ERR_error_string(ERR_get_error(), ssl_errstring);
89dd51cd 2048 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
ba084640
PP
2049 ssl_xfer_error = 1;
2050 return EOF;
2051 }
2052
059ec3d9
PH
2053 else if (error != SSL_ERROR_NONE)
2054 {
2055 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2056 ssl_xfer_error = 1;
2057 return EOF;
2058 }
c80c5570 2059
80a47a2c
TK
2060#ifndef DISABLE_DKIM
2061 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2062#endif
059ec3d9
PH
2063 ssl_xfer_buffer_hwm = inbytes;
2064 ssl_xfer_buffer_lwm = 0;
2065 }
2066
2067/* Something in the buffer; return next uschar */
2068
2069return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2070}
2071
2072
2073
2074/*************************************************
2075* Read bytes from TLS channel *
2076*************************************************/
2077
2078/*
2079Arguments:
2080 buff buffer of data
2081 len size of buffer
2082
2083Returns: the number of bytes read
2084 -1 after a failed read
817d9f57
JH
2085
2086Only used by the client-side TLS.
059ec3d9
PH
2087*/
2088
2089int
389ca47a 2090tls_read(BOOL is_server, uschar *buff, size_t len)
059ec3d9 2091{
389ca47a 2092SSL *ssl = is_server ? server_ssl : client_ssl;
059ec3d9
PH
2093int inbytes;
2094int error;
2095
389ca47a 2096DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
c80c5570 2097 buff, (unsigned int)len);
059ec3d9 2098
389ca47a
JH
2099inbytes = SSL_read(ssl, CS buff, len);
2100error = SSL_get_error(ssl, inbytes);
059ec3d9
PH
2101
2102if (error == SSL_ERROR_ZERO_RETURN)
2103 {
2104 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2105 return -1;
2106 }
2107else if (error != SSL_ERROR_NONE)
2108 {
2109 return -1;
2110 }
2111
2112return inbytes;
2113}
2114
2115
2116
2117
2118
2119/*************************************************
2120* Write bytes down TLS channel *
2121*************************************************/
2122
2123/*
2124Arguments:
817d9f57 2125 is_server channel specifier
059ec3d9
PH
2126 buff buffer of data
2127 len number of bytes
2128
2129Returns: the number of bytes after a successful write,
2130 -1 after a failed write
817d9f57
JH
2131
2132Used by both server-side and client-side TLS.
059ec3d9
PH
2133*/
2134
2135int
817d9f57 2136tls_write(BOOL is_server, const uschar *buff, size_t len)
059ec3d9
PH
2137{
2138int outbytes;
2139int error;
2140int left = len;
817d9f57 2141SSL *ssl = is_server ? server_ssl : client_ssl;
059ec3d9 2142
c80c5570 2143DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
059ec3d9
PH
2144while (left > 0)
2145 {
c80c5570 2146 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
059ec3d9
PH
2147 outbytes = SSL_write(ssl, CS buff, left);
2148 error = SSL_get_error(ssl, outbytes);
2149 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2150 switch (error)
2151 {
2152 case SSL_ERROR_SSL:
2153 ERR_error_string(ERR_get_error(), ssl_errstring);
2154 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2155 return -1;
2156
2157 case SSL_ERROR_NONE:
2158 left -= outbytes;
2159 buff += outbytes;
2160 break;
2161
2162 case SSL_ERROR_ZERO_RETURN:
2163 log_write(0, LOG_MAIN, "SSL channel closed on write");
2164 return -1;
2165
817d9f57
JH
2166 case SSL_ERROR_SYSCALL:
2167 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2168 sender_fullhost ? sender_fullhost : US"<unknown>",
2169 strerror(errno));
2170
059ec3d9
PH
2171 default:
2172 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2173 return -1;
2174 }
2175 }
2176return len;
2177}
2178
2179
2180
2181/*************************************************
2182* Close down a TLS session *
2183*************************************************/
2184
2185/* This is also called from within a delivery subprocess forked from the
2186daemon, to shut down the TLS library, without actually doing a shutdown (which
2187would tamper with the SSL session in the parent process).
2188
2189Arguments: TRUE if SSL_shutdown is to be called
2190Returns: nothing
817d9f57
JH
2191
2192Used by both server-side and client-side TLS.
059ec3d9
PH
2193*/
2194
2195void
817d9f57 2196tls_close(BOOL is_server, BOOL shutdown)
059ec3d9 2197{
817d9f57 2198SSL **sslp = is_server ? &server_ssl : &client_ssl;
389ca47a 2199int *fdp = is_server ? &tls_in.active : &tls_out.active;
817d9f57
JH
2200
2201if (*fdp < 0) return; /* TLS was not active */
059ec3d9
PH
2202
2203if (shutdown)
2204 {
2205 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
817d9f57 2206 SSL_shutdown(*sslp);
059ec3d9
PH
2207 }
2208
817d9f57
JH
2209SSL_free(*sslp);
2210*sslp = NULL;
059ec3d9 2211
817d9f57 2212*fdp = -1;
059ec3d9
PH
2213}
2214
36f12725
NM
2215
2216
2217
2218/*************************************************
3375e053
PP
2219* Let tls_require_ciphers be checked at startup *
2220*************************************************/
2221
2222/* The tls_require_ciphers option, if set, must be something which the
2223library can parse.
2224
2225Returns: NULL on success, or error message
2226*/
2227
2228uschar *
2229tls_validate_require_cipher(void)
2230{
2231SSL_CTX *ctx;
2232uschar *s, *expciphers, *err;
2233
2234/* this duplicates from tls_init(), we need a better "init just global
2235state, for no specific purpose" singleton function of our own */
2236
2237SSL_load_error_strings();
2238OpenSSL_add_ssl_algorithms();
2239#if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2240/* SHA256 is becoming ever more popular. This makes sure it gets added to the
2241list of available digests. */
2242EVP_add_digest(EVP_sha256());
2243#endif
2244
2245if (!(tls_require_ciphers && *tls_require_ciphers))
2246 return NULL;
2247
2248if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
2249 return US"failed to expand tls_require_ciphers";
2250
2251if (!(expciphers && *expciphers))
2252 return NULL;
2253
2254/* normalisation ripped from above */
2255s = expciphers;
2256while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2257
2258err = NULL;
2259
2260ctx = SSL_CTX_new(SSLv23_server_method());
2261if (!ctx)
2262 {
2263 ERR_error_string(ERR_get_error(), ssl_errstring);
2264 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2265 }
2266
2267DEBUG(D_tls)
2268 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2269
2270if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2271 {
2272 ERR_error_string(ERR_get_error(), ssl_errstring);
2273 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
2274 }
2275
2276SSL_CTX_free(ctx);
2277
2278return err;
2279}
2280
2281
2282
2283
2284/*************************************************
36f12725
NM
2285* Report the library versions. *
2286*************************************************/
2287
2288/* There have historically been some issues with binary compatibility in
2289OpenSSL libraries; if Exim (like many other applications) is built against
2290one version of OpenSSL but the run-time linker picks up another version,
2291it can result in serious failures, including crashing with a SIGSEGV. So
2292report the version found by the compiler and the run-time version.
2293
f64a1e23
PP
2294Note: some OS vendors backport security fixes without changing the version
2295number/string, and the version date remains unchanged. The _build_ date
2296will change, so we can more usefully assist with version diagnosis by also
2297reporting the build date.
2298
36f12725
NM
2299Arguments: a FILE* to print the results to
2300Returns: nothing
2301*/
2302
2303void
2304tls_version_report(FILE *f)
2305{
754a0503 2306fprintf(f, "Library version: OpenSSL: Compile: %s\n"
f64a1e23
PP
2307 " Runtime: %s\n"
2308 " : %s\n",
754a0503 2309 OPENSSL_VERSION_TEXT,
f64a1e23
PP
2310 SSLeay_version(SSLEAY_VERSION),
2311 SSLeay_version(SSLEAY_BUILT_ON));
2312/* third line is 38 characters for the %s and the line is 73 chars long;
2313the OpenSSL output includes a "built on: " prefix already. */
36f12725
NM
2314}
2315
9e3331ea
TK
2316
2317
2318
2319/*************************************************
17c76198 2320* Random number generation *
9e3331ea
TK
2321*************************************************/
2322
2323/* Pseudo-random number generation. The result is not expected to be
2324cryptographically strong but not so weak that someone will shoot themselves
2325in the foot using it as a nonce in input in some email header scheme or
2326whatever weirdness they'll twist this into. The result should handle fork()
2327and avoid repeating sequences. OpenSSL handles that for us.
2328
2329Arguments:
2330 max range maximum
2331Returns a random number in range [0, max-1]
2332*/
2333
2334int
17c76198 2335vaguely_random_number(int max)
9e3331ea
TK
2336{
2337unsigned int r;
2338int i, needed_len;
de6135a0
PP
2339static pid_t pidlast = 0;
2340pid_t pidnow;
9e3331ea
TK
2341uschar *p;
2342uschar smallbuf[sizeof(r)];
2343
2344if (max <= 1)
2345 return 0;
2346
de6135a0
PP
2347pidnow = getpid();
2348if (pidnow != pidlast)
2349 {
2350 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2351 is unique for each thread", this doesn't apparently apply across processes,
2352 so our own warning from vaguely_random_number_fallback() applies here too.
2353 Fix per PostgreSQL. */
2354 if (pidlast != 0)
2355 RAND_cleanup();
2356 pidlast = pidnow;
2357 }
2358
9e3331ea
TK
2359/* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2360if (!RAND_status())
2361 {
2362 randstuff r;
2363 gettimeofday(&r.tv, NULL);
2364 r.p = getpid();
2365
2366 RAND_seed((uschar *)(&r), sizeof(r));
2367 }
2368/* We're after pseudo-random, not random; if we still don't have enough data
2369in the internal PRNG then our options are limited. We could sleep and hope
2370for entropy to come along (prayer technique) but if the system is so depleted
2371in the first place then something is likely to just keep taking it. Instead,
2372we'll just take whatever little bit of pseudo-random we can still manage to
2373get. */
2374
2375needed_len = sizeof(r);
2376/* Don't take 8 times more entropy than needed if int is 8 octets and we were
2377asked for a number less than 10. */
2378for (r = max, i = 0; r; ++i)
2379 r >>= 1;
2380i = (i + 7) / 8;
2381if (i < needed_len)
2382 needed_len = i;
2383
2384/* We do not care if crypto-strong */
17c76198
PP
2385i = RAND_pseudo_bytes(smallbuf, needed_len);
2386if (i < 0)
2387 {
2388 DEBUG(D_all)
2389 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2390 return vaguely_random_number_fallback(max);
2391 }
2392
9e3331ea
TK
2393r = 0;
2394for (p = smallbuf; needed_len; --needed_len, ++p)
2395 {
2396 r *= 256;
2397 r += *p;
2398 }
2399
2400/* We don't particularly care about weighted results; if someone wants
2401smooth distribution and cares enough then they should submit a patch then. */
2402return r % max;
2403}
2404
77bb000f
PP
2405
2406
2407
2408/*************************************************
2409* OpenSSL option parse *
2410*************************************************/
2411
2412/* Parse one option for tls_openssl_options_parse below
2413
2414Arguments:
2415 name one option name
2416 value place to store a value for it
2417Returns success or failure in parsing
2418*/
2419
2420struct exim_openssl_option {
2421 uschar *name;
2422 long value;
2423};
2424/* We could use a macro to expand, but we need the ifdef and not all the
2425options document which version they were introduced in. Policylet: include
2426all options unless explicitly for DTLS, let the administrator choose which
2427to apply.
2428
2429This list is current as of:
e2fbf4a2
PP
2430 ==> 1.0.1b <==
2431Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2432*/
77bb000f
PP
2433static struct exim_openssl_option exim_openssl_options[] = {
2434/* KEEP SORTED ALPHABETICALLY! */
2435#ifdef SSL_OP_ALL
73a46702 2436 { US"all", SSL_OP_ALL },
77bb000f
PP
2437#endif
2438#ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
73a46702 2439 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
77bb000f
PP
2440#endif
2441#ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
73a46702 2442 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
77bb000f
PP
2443#endif
2444#ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
73a46702 2445 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
77bb000f
PP
2446#endif
2447#ifdef SSL_OP_EPHEMERAL_RSA
73a46702 2448 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
77bb000f
PP
2449#endif
2450#ifdef SSL_OP_LEGACY_SERVER_CONNECT
73a46702 2451 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
77bb000f
PP
2452#endif
2453#ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
73a46702 2454 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
77bb000f
PP
2455#endif
2456#ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
73a46702 2457 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
77bb000f
PP
2458#endif
2459#ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
73a46702 2460 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
77bb000f
PP
2461#endif
2462#ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
73a46702 2463 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
77bb000f
PP
2464#endif
2465#ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
73a46702 2466 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
77bb000f 2467#endif
c80c5570
PP
2468#ifdef SSL_OP_NO_COMPRESSION
2469 { US"no_compression", SSL_OP_NO_COMPRESSION },
2470#endif
77bb000f 2471#ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
73a46702 2472 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
77bb000f 2473#endif
c0c7b2da
PP
2474#ifdef SSL_OP_NO_SSLv2
2475 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2476#endif
2477#ifdef SSL_OP_NO_SSLv3
2478 { US"no_sslv3", SSL_OP_NO_SSLv3 },
2479#endif
2480#ifdef SSL_OP_NO_TICKET
2481 { US"no_ticket", SSL_OP_NO_TICKET },
2482#endif
2483#ifdef SSL_OP_NO_TLSv1
2484 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
2485#endif
c80c5570
PP
2486#ifdef SSL_OP_NO_TLSv1_1
2487#if SSL_OP_NO_TLSv1_1 == 0x00000400L
2488 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2489#warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2490#else
2491 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
2492#endif
2493#endif
2494#ifdef SSL_OP_NO_TLSv1_2
2495 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
2496#endif
e2fbf4a2
PP
2497#ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2498 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
2499#endif
77bb000f 2500#ifdef SSL_OP_SINGLE_DH_USE
73a46702 2501 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
77bb000f
PP
2502#endif
2503#ifdef SSL_OP_SINGLE_ECDH_USE
73a46702 2504 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
77bb000f
PP
2505#endif
2506#ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
73a46702 2507 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
77bb000f
PP
2508#endif
2509#ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
73a46702 2510 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
77bb000f
PP
2511#endif
2512#ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
73a46702 2513 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
77bb000f
PP
2514#endif
2515#ifdef SSL_OP_TLS_D5_BUG
73a46702 2516 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
77bb000f
PP
2517#endif
2518#ifdef SSL_OP_TLS_ROLLBACK_BUG
73a46702 2519 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
77bb000f
PP
2520#endif
2521};
2522static int exim_openssl_options_size =
2523 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
2524
c80c5570 2525
77bb000f
PP
2526static BOOL
2527tls_openssl_one_option_parse(uschar *name, long *value)
2528{
2529int first = 0;
2530int last = exim_openssl_options_size;
2531while (last > first)
2532 {
2533 int middle = (first + last)/2;
2534 int c = Ustrcmp(name, exim_openssl_options[middle].name);
2535 if (c == 0)
2536 {
2537 *value = exim_openssl_options[middle].value;
2538 return TRUE;
2539 }
2540 else if (c > 0)
2541 first = middle + 1;
2542 else
2543 last = middle;
2544 }
2545return FALSE;
2546}
2547
2548
2549
2550
2551/*************************************************
2552* OpenSSL option parsing logic *
2553*************************************************/
2554
2555/* OpenSSL has a number of compatibility options which an administrator might
2556reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2557we look like log_selector.
2558
2559Arguments:
2560 option_spec the administrator-supplied string of options
2561 results ptr to long storage for the options bitmap
2562Returns success or failure
2563*/
2564
2565BOOL
2566tls_openssl_options_parse(uschar *option_spec, long *results)
2567{
2568long result, item;
2569uschar *s, *end;
2570uschar keep_c;
2571BOOL adding, item_parsed;
2572
0e944a0d 2573result = 0L;
b1770b6e 2574/* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
da3ad30d 2575 * from default because it increases BEAST susceptibility. */
f0f5a555
PP
2576#ifdef SSL_OP_NO_SSLv2
2577result |= SSL_OP_NO_SSLv2;
2578#endif
77bb000f
PP
2579
2580if (option_spec == NULL)
2581 {
2582 *results = result;
2583 return TRUE;
2584 }
2585
2586for (s=option_spec; *s != '\0'; /**/)
2587 {
2588 while (isspace(*s)) ++s;
2589 if (*s == '\0')
2590 break;
2591 if (*s != '+' && *s != '-')
2592 {
2593 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
0e944a0d 2594 "+ or - expected but found \"%s\"\n", s);
77bb000f
PP
2595 return FALSE;
2596 }
2597 adding = *s++ == '+';
2598 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
2599 keep_c = *end;
2600 *end = '\0';
2601 item_parsed = tls_openssl_one_option_parse(s, &item);
2602 if (!item_parsed)
2603 {
0e944a0d 2604 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
77bb000f
PP
2605 return FALSE;
2606 }
2607 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2608 adding ? "adding" : "removing", result, item, s);
2609 if (adding)
2610 result |= item;
2611 else
2612 result &= ~item;
2613 *end = keep_c;
2614 s = end;
2615 }
2616
2617*results = result;
2618return TRUE;
2619}
2620
9d1c15ef
JH
2621/* vi: aw ai sw=2
2622*/
059ec3d9 2623/* End of tls-openssl.c */