Commit | Line | Data |
---|---|---|
059ec3d9 PH |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | ||
0a49a7a4 | 5 | /* Copyright (c) University of Cambridge 1995 - 2009 */ |
059ec3d9 PH |
6 | /* See the file NOTICE for conditions of use and distribution. */ |
7 | ||
8 | /* This module provides the TLS (aka SSL) support for Exim using the OpenSSL | |
9 | library. It is #included into the tls.c file when that library is used. The | |
10 | code herein is based on a patch that was originally contributed by Steve | |
11 | Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara. | |
12 | ||
13 | No cryptographic code is included in Exim. All this module does is to call | |
14 | functions from the OpenSSL library. */ | |
15 | ||
16 | ||
17 | /* Heading stuff */ | |
18 | ||
19 | #include <openssl/lhash.h> | |
20 | #include <openssl/ssl.h> | |
21 | #include <openssl/err.h> | |
22 | #include <openssl/rand.h> | |
23 | ||
24 | /* Structure for collecting random data for seeding. */ | |
25 | ||
26 | typedef struct randstuff { | |
9e3331ea TK |
27 | struct timeval tv; |
28 | pid_t p; | |
059ec3d9 PH |
29 | } randstuff; |
30 | ||
31 | /* Local static variables */ | |
32 | ||
33 | static BOOL verify_callback_called = FALSE; | |
34 | static const uschar *sid_ctx = US"exim"; | |
35 | ||
36 | static SSL_CTX *ctx = NULL; | |
7be682ca | 37 | static SSL_CTX *ctx_sni = NULL; |
059ec3d9 PH |
38 | static SSL *ssl = NULL; |
39 | ||
40 | static char ssl_errstring[256]; | |
41 | ||
42 | static int ssl_session_timeout = 200; | |
43 | static BOOL verify_optional = FALSE; | |
44 | ||
7be682ca | 45 | static BOOL reexpand_tls_files_for_sni = FALSE; |
059ec3d9 PH |
46 | |
47 | ||
7be682ca PP |
48 | typedef struct tls_ext_ctx_cb { |
49 | uschar *certificate; | |
50 | uschar *privatekey; | |
51 | uschar *dhparam; | |
52 | /* these are cached from first expand */ | |
53 | uschar *server_cipher_list; | |
54 | /* only passed down to tls_error: */ | |
55 | host_item *host; | |
56 | } tls_ext_ctx_cb; | |
57 | ||
58 | /* should figure out a cleanup of API to handle state preserved per | |
59 | implementation, for various reasons, which can be void * in the APIs. | |
60 | For now, we hack around it. */ | |
61 | tls_ext_ctx_cb *static_cbinfo = NULL; | |
62 | ||
63 | static int | |
64 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional); | |
059ec3d9 PH |
65 | |
66 | ||
67 | /************************************************* | |
68 | * Handle TLS error * | |
69 | *************************************************/ | |
70 | ||
71 | /* Called from lots of places when errors occur before actually starting to do | |
72 | the TLS handshake, that is, while the session is still in clear. Always returns | |
73 | DEFER for a server and FAIL for a client so that most calls can use "return | |
74 | tls_error(...)" to do this processing and then give an appropriate return. A | |
75 | single function is used for both server and client, because it is called from | |
76 | some shared functions. | |
77 | ||
78 | Argument: | |
79 | prefix text to include in the logged error | |
80 | host NULL if setting up a server; | |
81 | the connected host if setting up a client | |
7199e1ee | 82 | msg error message or NULL if we should ask OpenSSL |
059ec3d9 PH |
83 | |
84 | Returns: OK/DEFER/FAIL | |
85 | */ | |
86 | ||
87 | static int | |
7199e1ee | 88 | tls_error(uschar *prefix, host_item *host, uschar *msg) |
059ec3d9 | 89 | { |
7199e1ee TF |
90 | if (msg == NULL) |
91 | { | |
92 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
5ca6d115 | 93 | msg = (uschar *)ssl_errstring; |
7199e1ee TF |
94 | } |
95 | ||
059ec3d9 PH |
96 | if (host == NULL) |
97 | { | |
7199e1ee | 98 | uschar *conn_info = smtp_get_connection_info(); |
5ca6d115 | 99 | if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) |
7199e1ee TF |
100 | conn_info += 5; |
101 | log_write(0, LOG_MAIN, "TLS error on %s (%s): %s", | |
102 | conn_info, prefix, msg); | |
059ec3d9 PH |
103 | return DEFER; |
104 | } | |
105 | else | |
106 | { | |
107 | log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s): %s", | |
7199e1ee | 108 | host->name, host->address, prefix, msg); |
059ec3d9 PH |
109 | return FAIL; |
110 | } | |
111 | } | |
112 | ||
113 | ||
114 | ||
115 | /************************************************* | |
116 | * Callback to generate RSA key * | |
117 | *************************************************/ | |
118 | ||
119 | /* | |
120 | Arguments: | |
121 | s SSL connection | |
122 | export not used | |
123 | keylength keylength | |
124 | ||
125 | Returns: pointer to generated key | |
126 | */ | |
127 | ||
128 | static RSA * | |
129 | rsa_callback(SSL *s, int export, int keylength) | |
130 | { | |
131 | RSA *rsa_key; | |
132 | export = export; /* Shut picky compilers up */ | |
133 | DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength); | |
134 | rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL); | |
135 | if (rsa_key == NULL) | |
136 | { | |
137 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
138 | log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s", | |
139 | ssl_errstring); | |
140 | return NULL; | |
141 | } | |
142 | return rsa_key; | |
143 | } | |
144 | ||
145 | ||
146 | ||
147 | ||
148 | /************************************************* | |
149 | * Callback for verification * | |
150 | *************************************************/ | |
151 | ||
152 | /* The SSL library does certificate verification if set up to do so. This | |
153 | callback has the current yes/no state is in "state". If verification succeeded, | |
154 | we set up the tls_peerdn string. If verification failed, what happens depends | |
155 | on whether the client is required to present a verifiable certificate or not. | |
156 | ||
157 | If verification is optional, we change the state to yes, but still log the | |
158 | verification error. For some reason (it really would help to have proper | |
159 | documentation of OpenSSL), this callback function then gets called again, this | |
160 | time with state = 1. In fact, that's useful, because we can set up the peerdn | |
161 | value, but we must take care not to set the private verified flag on the second | |
162 | time through. | |
163 | ||
164 | Note: this function is not called if the client fails to present a certificate | |
165 | when asked. We get here only if a certificate has been received. Handling of | |
166 | optional verification for this case is done when requesting SSL to verify, by | |
167 | setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case. | |
168 | ||
169 | Arguments: | |
170 | state current yes/no state as 1/0 | |
171 | x509ctx certificate information. | |
172 | ||
173 | Returns: 1 if verified, 0 if not | |
174 | */ | |
175 | ||
176 | static int | |
177 | verify_callback(int state, X509_STORE_CTX *x509ctx) | |
178 | { | |
179 | static uschar txt[256]; | |
180 | ||
181 | X509_NAME_oneline(X509_get_subject_name(x509ctx->current_cert), | |
182 | CS txt, sizeof(txt)); | |
183 | ||
184 | if (state == 0) | |
185 | { | |
186 | log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s", | |
187 | x509ctx->error_depth, | |
188 | X509_verify_cert_error_string(x509ctx->error), | |
189 | txt); | |
190 | tls_certificate_verified = FALSE; | |
191 | verify_callback_called = TRUE; | |
192 | if (!verify_optional) return 0; /* reject */ | |
193 | DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in " | |
194 | "tls_try_verify_hosts)\n"); | |
195 | return 1; /* accept */ | |
196 | } | |
197 | ||
198 | if (x509ctx->error_depth != 0) | |
199 | { | |
200 | DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d cert=%s\n", | |
201 | x509ctx->error_depth, txt); | |
202 | } | |
203 | else | |
204 | { | |
205 | DEBUG(D_tls) debug_printf("SSL%s peer: %s\n", | |
206 | verify_callback_called? "" : " authenticated", txt); | |
207 | tls_peerdn = txt; | |
208 | } | |
209 | ||
059ec3d9 PH |
210 | if (!verify_callback_called) tls_certificate_verified = TRUE; |
211 | verify_callback_called = TRUE; | |
212 | ||
213 | return 1; /* accept */ | |
214 | } | |
215 | ||
216 | ||
217 | ||
218 | /************************************************* | |
219 | * Information callback * | |
220 | *************************************************/ | |
221 | ||
222 | /* The SSL library functions call this from time to time to indicate what they | |
7be682ca PP |
223 | are doing. We copy the string to the debugging output when TLS debugging has |
224 | been requested. | |
059ec3d9 PH |
225 | |
226 | Arguments: | |
227 | s the SSL connection | |
228 | where | |
229 | ret | |
230 | ||
231 | Returns: nothing | |
232 | */ | |
233 | ||
234 | static void | |
235 | info_callback(SSL *s, int where, int ret) | |
236 | { | |
237 | where = where; | |
238 | ret = ret; | |
239 | DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s)); | |
240 | } | |
241 | ||
242 | ||
243 | ||
244 | /************************************************* | |
245 | * Initialize for DH * | |
246 | *************************************************/ | |
247 | ||
248 | /* If dhparam is set, expand it, and load up the parameters for DH encryption. | |
249 | ||
250 | Arguments: | |
251 | dhparam DH parameter file | |
7199e1ee | 252 | host connected host, if client; NULL if server |
059ec3d9 PH |
253 | |
254 | Returns: TRUE if OK (nothing to set up, or setup worked) | |
255 | */ | |
256 | ||
257 | static BOOL | |
7199e1ee | 258 | init_dh(uschar *dhparam, host_item *host) |
059ec3d9 PH |
259 | { |
260 | BOOL yield = TRUE; | |
261 | BIO *bio; | |
262 | DH *dh; | |
263 | uschar *dhexpanded; | |
264 | ||
265 | if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded)) | |
266 | return FALSE; | |
267 | ||
268 | if (dhexpanded == NULL) return TRUE; | |
269 | ||
270 | if ((bio = BIO_new_file(CS dhexpanded, "r")) == NULL) | |
271 | { | |
7199e1ee | 272 | tls_error(string_sprintf("could not read dhparams file %s", dhexpanded), |
5ca6d115 | 273 | host, (uschar *)strerror(errno)); |
059ec3d9 PH |
274 | yield = FALSE; |
275 | } | |
276 | else | |
277 | { | |
278 | if ((dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)) == NULL) | |
279 | { | |
7199e1ee TF |
280 | tls_error(string_sprintf("could not read dhparams file %s", dhexpanded), |
281 | host, NULL); | |
059ec3d9 PH |
282 | yield = FALSE; |
283 | } | |
284 | else | |
285 | { | |
286 | SSL_CTX_set_tmp_dh(ctx, dh); | |
287 | DEBUG(D_tls) | |
288 | debug_printf("Diffie-Hellman initialized from %s with %d-bit key\n", | |
289 | dhexpanded, 8*DH_size(dh)); | |
290 | DH_free(dh); | |
291 | } | |
292 | BIO_free(bio); | |
293 | } | |
294 | ||
295 | return yield; | |
296 | } | |
297 | ||
298 | ||
299 | ||
300 | ||
7be682ca PP |
301 | /************************************************* |
302 | * Expand key and cert file specs * | |
303 | *************************************************/ | |
304 | ||
305 | /* Called once during tls_init and possibly againt during TLS setup, for a | |
306 | new context, if Server Name Indication was used and tls_sni was seen in | |
307 | the certificate string. | |
308 | ||
309 | Arguments: | |
310 | sctx the SSL_CTX* to update | |
311 | cbinfo various parts of session state | |
312 | ||
313 | Returns: OK/DEFER/FAIL | |
314 | */ | |
315 | ||
316 | static int | |
317 | tls_expand_session_files(SSL_CTX *sctx, const tls_ext_ctx_cb *cbinfo) | |
318 | { | |
319 | uschar *expanded; | |
320 | ||
321 | if (cbinfo->certificate == NULL) | |
322 | return OK; | |
323 | ||
324 | if (Ustrstr(cbinfo->certificate, US"tls_sni")) | |
325 | reexpand_tls_files_for_sni = TRUE; | |
326 | ||
327 | if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded)) | |
328 | return DEFER; | |
329 | ||
330 | if (expanded != NULL) | |
331 | { | |
332 | DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded); | |
333 | if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded)) | |
334 | return tls_error(string_sprintf( | |
335 | "SSL_CTX_use_certificate_chain_file file=%s", expanded), | |
336 | cbinfo->host, NULL); | |
337 | } | |
338 | ||
339 | if (cbinfo->privatekey != NULL && | |
340 | !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded)) | |
341 | return DEFER; | |
342 | ||
343 | /* If expansion was forced to fail, key_expanded will be NULL. If the result | |
344 | of the expansion is an empty string, ignore it also, and assume the private | |
345 | key is in the same file as the certificate. */ | |
346 | ||
347 | if (expanded != NULL && *expanded != 0) | |
348 | { | |
349 | DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded); | |
350 | if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM)) | |
351 | return tls_error(string_sprintf( | |
352 | "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL); | |
353 | } | |
354 | ||
355 | return OK; | |
356 | } | |
357 | ||
358 | ||
359 | ||
360 | ||
361 | /************************************************* | |
362 | * Callback to handle SNI * | |
363 | *************************************************/ | |
364 | ||
365 | /* Called when acting as server during the TLS session setup if a Server Name | |
366 | Indication extension was sent by the client. | |
367 | ||
368 | API documentation is OpenSSL s_server.c implementation. | |
369 | ||
370 | Arguments: | |
371 | s SSL* of the current session | |
372 | ad unknown (part of OpenSSL API) (unused) | |
373 | arg Callback of "our" registered data | |
374 | ||
375 | Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK} | |
376 | */ | |
377 | ||
378 | static int | |
379 | tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg); | |
380 | /* pre-declared for SSL_CTX_set_tlsext_servername_callback call within func */ | |
381 | ||
382 | static int | |
383 | tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg) | |
384 | { | |
385 | const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name); | |
386 | const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg; | |
387 | int rc; | |
388 | ||
389 | if (!servername) | |
390 | return SSL_TLSEXT_ERR_OK; | |
391 | ||
392 | DEBUG(D_tls) debug_printf("TLS SNI: %s%s\n", servername, | |
393 | reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)"); | |
394 | ||
395 | /* Make the extension value available for expansion */ | |
396 | tls_sni = servername; | |
397 | ||
398 | if (!reexpand_tls_files_for_sni) | |
399 | return SSL_TLSEXT_ERR_OK; | |
400 | ||
401 | /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually; | |
402 | not confident that memcpy wouldn't break some internal reference counting. | |
403 | Especially since there's a references struct member, which would be off. */ | |
404 | ||
405 | ctx_sni = SSL_CTX_new(SSLv23_server_method()); | |
406 | if (!ctx_sni) | |
407 | { | |
408 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
409 | DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring); | |
410 | return SSL_TLSEXT_ERR_NOACK; | |
411 | } | |
412 | ||
413 | /* Not sure how many of these are actually needed, since SSL object | |
414 | already exists. Might even need this selfsame callback, for reneg? */ | |
415 | ||
416 | SSL_CTX_set_info_callback(ctx_sni, SSL_CTX_get_info_callback(ctx)); | |
417 | SSL_CTX_set_mode(ctx_sni, SSL_CTX_get_mode(ctx)); | |
418 | SSL_CTX_set_options(ctx_sni, SSL_CTX_get_options(ctx)); | |
419 | SSL_CTX_set_timeout(ctx_sni, SSL_CTX_get_timeout(ctx)); | |
420 | SSL_CTX_set_tlsext_servername_callback(ctx_sni, tls_servername_cb); | |
421 | SSL_CTX_set_tlsext_servername_arg(ctx_sni, cbinfo); | |
422 | if (cbinfo->server_cipher_list) | |
423 | SSL_CTX_set_cipher_list(ctx_sni, CS cbinfo->server_cipher_list); | |
424 | ||
425 | rc = tls_expand_session_files(ctx_sni, cbinfo); | |
426 | if (rc != OK) return SSL_TLSEXT_ERR_NOACK; | |
427 | ||
428 | rc = setup_certs(ctx_sni, tls_verify_certificates, tls_crl, NULL, FALSE); | |
429 | if (rc != OK) return SSL_TLSEXT_ERR_NOACK; | |
430 | ||
431 | DEBUG(D_tls) debug_printf("Switching SSL context.\n"); | |
432 | SSL_set_SSL_CTX(s, ctx_sni); | |
433 | ||
434 | return SSL_TLSEXT_ERR_OK; | |
435 | } | |
436 | ||
437 | ||
438 | ||
439 | ||
059ec3d9 PH |
440 | /************************************************* |
441 | * Initialize for TLS * | |
442 | *************************************************/ | |
443 | ||
444 | /* Called from both server and client code, to do preliminary initialization of | |
445 | the library. | |
446 | ||
447 | Arguments: | |
448 | host connected host, if client; NULL if server | |
449 | dhparam DH parameter file | |
450 | certificate certificate file | |
451 | privatekey private key | |
452 | addr address if client; NULL if server (for some randomness) | |
453 | ||
454 | Returns: OK/DEFER/FAIL | |
455 | */ | |
456 | ||
457 | static int | |
c91535f3 PH |
458 | tls_init(host_item *host, uschar *dhparam, uschar *certificate, |
459 | uschar *privatekey, address_item *addr) | |
059ec3d9 | 460 | { |
77bb000f | 461 | long init_options; |
7be682ca | 462 | int rc; |
77bb000f | 463 | BOOL okay; |
7be682ca PP |
464 | tls_ext_ctx_cb *cbinfo; |
465 | ||
466 | cbinfo = store_malloc(sizeof(tls_ext_ctx_cb)); | |
467 | cbinfo->certificate = certificate; | |
468 | cbinfo->privatekey = privatekey; | |
469 | cbinfo->dhparam = dhparam; | |
470 | cbinfo->host = host; | |
77bb000f | 471 | |
059ec3d9 PH |
472 | SSL_load_error_strings(); /* basic set up */ |
473 | OpenSSL_add_ssl_algorithms(); | |
474 | ||
388d6564 | 475 | #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256) |
77bb000f | 476 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the |
a0475b69 TK |
477 | list of available digests. */ |
478 | EVP_add_digest(EVP_sha256()); | |
cf1ef1a9 | 479 | #endif |
a0475b69 | 480 | |
059ec3d9 PH |
481 | /* Create a context */ |
482 | ||
483 | ctx = SSL_CTX_new((host == NULL)? | |
484 | SSLv23_server_method() : SSLv23_client_method()); | |
485 | ||
7199e1ee | 486 | if (ctx == NULL) return tls_error(US"SSL_CTX_new", host, NULL); |
059ec3d9 PH |
487 | |
488 | /* It turns out that we need to seed the random number generator this early in | |
489 | order to get the full complement of ciphers to work. It took me roughly a day | |
490 | of work to discover this by experiment. | |
491 | ||
492 | On systems that have /dev/urandom, SSL may automatically seed itself from | |
493 | there. Otherwise, we have to make something up as best we can. Double check | |
494 | afterwards. */ | |
495 | ||
496 | if (!RAND_status()) | |
497 | { | |
498 | randstuff r; | |
9e3331ea | 499 | gettimeofday(&r.tv, NULL); |
059ec3d9 PH |
500 | r.p = getpid(); |
501 | ||
502 | RAND_seed((uschar *)(&r), sizeof(r)); | |
503 | RAND_seed((uschar *)big_buffer, big_buffer_size); | |
504 | if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr)); | |
505 | ||
506 | if (!RAND_status()) | |
7199e1ee | 507 | return tls_error(US"RAND_status", host, |
5ca6d115 | 508 | US"unable to seed random number generator"); |
059ec3d9 PH |
509 | } |
510 | ||
511 | /* Set up the information callback, which outputs if debugging is at a suitable | |
512 | level. */ | |
513 | ||
58c01c94 | 514 | SSL_CTX_set_info_callback(ctx, (void (*)())info_callback); |
059ec3d9 | 515 | |
c80c5570 PP |
516 | /* Automatically re-try reads/writes after renegotiation. */ |
517 | (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY); | |
518 | ||
77bb000f PP |
519 | /* Apply administrator-supplied work-arounds. |
520 | Historically we applied just one requested option, | |
521 | SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we | |
522 | moved to an administrator-controlled list of options to specify and | |
523 | grandfathered in the first one as the default value for "openssl_options". | |
059ec3d9 | 524 | |
77bb000f PP |
525 | No OpenSSL version number checks: the options we accept depend upon the |
526 | availability of the option value macros from OpenSSL. */ | |
059ec3d9 | 527 | |
77bb000f PP |
528 | okay = tls_openssl_options_parse(openssl_options, &init_options); |
529 | if (!okay) | |
73a46702 | 530 | return tls_error(US"openssl_options parsing failed", host, NULL); |
77bb000f PP |
531 | |
532 | if (init_options) | |
533 | { | |
534 | DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options); | |
535 | if (!(SSL_CTX_set_options(ctx, init_options))) | |
536 | return tls_error(string_sprintf( | |
537 | "SSL_CTX_set_option(%#lx)", init_options), host, NULL); | |
538 | } | |
539 | else | |
540 | DEBUG(D_tls) debug_printf("no SSL CTX options to set\n"); | |
059ec3d9 PH |
541 | |
542 | /* Initialize with DH parameters if supplied */ | |
543 | ||
7199e1ee | 544 | if (!init_dh(dhparam, host)) return DEFER; |
059ec3d9 PH |
545 | |
546 | /* Set up certificate and key */ | |
547 | ||
7be682ca PP |
548 | rc = tls_expand_session_files(ctx, cbinfo); |
549 | if (rc != OK) return rc; | |
c91535f3 | 550 | |
7be682ca PP |
551 | /* If we need to handle SNI, do so */ |
552 | #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT) | |
553 | /* We always do this, so that $tls_sni is available even if not used in | |
554 | tls_certificate */ | |
555 | SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb); | |
556 | SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo); | |
557 | #endif | |
059ec3d9 PH |
558 | |
559 | /* Set up the RSA callback */ | |
560 | ||
561 | SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback); | |
562 | ||
563 | /* Finally, set the timeout, and we are done */ | |
564 | ||
565 | SSL_CTX_set_timeout(ctx, ssl_session_timeout); | |
566 | DEBUG(D_tls) debug_printf("Initialized TLS\n"); | |
7be682ca PP |
567 | |
568 | static_cbinfo = cbinfo; | |
569 | ||
059ec3d9 PH |
570 | return OK; |
571 | } | |
572 | ||
573 | ||
574 | ||
575 | ||
576 | /************************************************* | |
577 | * Get name of cipher in use * | |
578 | *************************************************/ | |
579 | ||
580 | /* The answer is left in a static buffer, and tls_cipher is set to point | |
581 | to it. | |
582 | ||
583 | Argument: pointer to an SSL structure for the connection | |
584 | Returns: nothing | |
585 | */ | |
586 | ||
587 | static void | |
588 | construct_cipher_name(SSL *ssl) | |
589 | { | |
590 | static uschar cipherbuf[256]; | |
57b3a7f5 PP |
591 | /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't |
592 | yet reflect that. It should be a safe change anyway, even 0.9.8 versions have | |
593 | the accessor functions use const in the prototype. */ | |
594 | const SSL_CIPHER *c; | |
059ec3d9 | 595 | uschar *ver; |
059ec3d9 PH |
596 | |
597 | switch (ssl->session->ssl_version) | |
598 | { | |
599 | case SSL2_VERSION: | |
600 | ver = US"SSLv2"; | |
601 | break; | |
602 | ||
603 | case SSL3_VERSION: | |
604 | ver = US"SSLv3"; | |
605 | break; | |
606 | ||
607 | case TLS1_VERSION: | |
608 | ver = US"TLSv1"; | |
609 | break; | |
610 | ||
c80c5570 PP |
611 | #ifdef TLS1_1_VERSION |
612 | case TLS1_1_VERSION: | |
613 | ver = US"TLSv1.1"; | |
614 | break; | |
615 | #endif | |
616 | ||
617 | #ifdef TLS1_2_VERSION | |
618 | case TLS1_2_VERSION: | |
619 | ver = US"TLSv1.2"; | |
620 | break; | |
621 | #endif | |
622 | ||
059ec3d9 PH |
623 | default: |
624 | ver = US"UNKNOWN"; | |
625 | } | |
626 | ||
57b3a7f5 | 627 | c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl); |
edc33b5f | 628 | SSL_CIPHER_get_bits(c, &tls_bits); |
059ec3d9 PH |
629 | |
630 | string_format(cipherbuf, sizeof(cipherbuf), "%s:%s:%u", ver, | |
edc33b5f | 631 | SSL_CIPHER_get_name(c), tls_bits); |
059ec3d9 PH |
632 | tls_cipher = cipherbuf; |
633 | ||
634 | DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf); | |
635 | } | |
636 | ||
637 | ||
638 | ||
639 | ||
640 | ||
641 | /************************************************* | |
642 | * Set up for verifying certificates * | |
643 | *************************************************/ | |
644 | ||
645 | /* Called by both client and server startup | |
646 | ||
647 | Arguments: | |
7be682ca | 648 | sctx SSL_CTX* to initialise |
059ec3d9 PH |
649 | certs certs file or NULL |
650 | crl CRL file or NULL | |
651 | host NULL in a server; the remote host in a client | |
652 | optional TRUE if called from a server for a host in tls_try_verify_hosts; | |
653 | otherwise passed as FALSE | |
654 | ||
655 | Returns: OK/DEFER/FAIL | |
656 | */ | |
657 | ||
658 | static int | |
7be682ca | 659 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional) |
059ec3d9 PH |
660 | { |
661 | uschar *expcerts, *expcrl; | |
662 | ||
663 | if (!expand_check(certs, US"tls_verify_certificates", &expcerts)) | |
664 | return DEFER; | |
665 | ||
666 | if (expcerts != NULL) | |
667 | { | |
668 | struct stat statbuf; | |
7be682ca | 669 | if (!SSL_CTX_set_default_verify_paths(sctx)) |
7199e1ee | 670 | return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL); |
059ec3d9 PH |
671 | |
672 | if (Ustat(expcerts, &statbuf) < 0) | |
673 | { | |
674 | log_write(0, LOG_MAIN|LOG_PANIC, | |
675 | "failed to stat %s for certificates", expcerts); | |
676 | return DEFER; | |
677 | } | |
678 | else | |
679 | { | |
680 | uschar *file, *dir; | |
681 | if ((statbuf.st_mode & S_IFMT) == S_IFDIR) | |
682 | { file = NULL; dir = expcerts; } | |
683 | else | |
684 | { file = expcerts; dir = NULL; } | |
685 | ||
686 | /* If a certificate file is empty, the next function fails with an | |
687 | unhelpful error message. If we skip it, we get the correct behaviour (no | |
688 | certificates are recognized, but the error message is still misleading (it | |
689 | says no certificate was supplied.) But this is better. */ | |
690 | ||
691 | if ((file == NULL || statbuf.st_size > 0) && | |
7be682ca | 692 | !SSL_CTX_load_verify_locations(sctx, CS file, CS dir)) |
7199e1ee | 693 | return tls_error(US"SSL_CTX_load_verify_locations", host, NULL); |
059ec3d9 PH |
694 | |
695 | if (file != NULL) | |
696 | { | |
7be682ca | 697 | SSL_CTX_set_client_CA_list(sctx, SSL_load_client_CA_file(CS file)); |
059ec3d9 PH |
698 | } |
699 | } | |
700 | ||
701 | /* Handle a certificate revocation list. */ | |
702 | ||
703 | #if OPENSSL_VERSION_NUMBER > 0x00907000L | |
704 | ||
8b417f2c PH |
705 | /* This bit of code is now the version supplied by Lars Mainka. (I have |
706 | * merely reformatted it into the Exim code style.) | |
707 | ||
708 | * "From here I changed the code to add support for multiple crl's | |
709 | * in pem format in one file or to support hashed directory entries in | |
710 | * pem format instead of a file. This method now uses the library function | |
711 | * X509_STORE_load_locations to add the CRL location to the SSL context. | |
712 | * OpenSSL will then handle the verify against CA certs and CRLs by | |
713 | * itself in the verify callback." */ | |
714 | ||
059ec3d9 PH |
715 | if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER; |
716 | if (expcrl != NULL && *expcrl != 0) | |
717 | { | |
8b417f2c PH |
718 | struct stat statbufcrl; |
719 | if (Ustat(expcrl, &statbufcrl) < 0) | |
720 | { | |
721 | log_write(0, LOG_MAIN|LOG_PANIC, | |
722 | "failed to stat %s for certificates revocation lists", expcrl); | |
723 | return DEFER; | |
724 | } | |
725 | else | |
059ec3d9 | 726 | { |
8b417f2c PH |
727 | /* is it a file or directory? */ |
728 | uschar *file, *dir; | |
7be682ca | 729 | X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx); |
8b417f2c | 730 | if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR) |
059ec3d9 | 731 | { |
8b417f2c PH |
732 | file = NULL; |
733 | dir = expcrl; | |
734 | DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir); | |
059ec3d9 PH |
735 | } |
736 | else | |
737 | { | |
8b417f2c PH |
738 | file = expcrl; |
739 | dir = NULL; | |
740 | DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file); | |
059ec3d9 | 741 | } |
8b417f2c | 742 | if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0) |
7199e1ee | 743 | return tls_error(US"X509_STORE_load_locations", host, NULL); |
8b417f2c PH |
744 | |
745 | /* setting the flags to check against the complete crl chain */ | |
746 | ||
747 | X509_STORE_set_flags(cvstore, | |
748 | X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL); | |
059ec3d9 | 749 | } |
059ec3d9 PH |
750 | } |
751 | ||
752 | #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */ | |
753 | ||
754 | /* If verification is optional, don't fail if no certificate */ | |
755 | ||
7be682ca | 756 | SSL_CTX_set_verify(sctx, |
059ec3d9 PH |
757 | SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT), |
758 | verify_callback); | |
759 | } | |
760 | ||
761 | return OK; | |
762 | } | |
763 | ||
764 | ||
765 | ||
766 | /************************************************* | |
767 | * Start a TLS session in a server * | |
768 | *************************************************/ | |
769 | ||
770 | /* This is called when Exim is running as a server, after having received | |
771 | the STARTTLS command. It must respond to that command, and then negotiate | |
772 | a TLS session. | |
773 | ||
774 | Arguments: | |
775 | require_ciphers allowed ciphers | |
83da1223 PH |
776 | ------------------------------------------------------ |
777 | require_mac list of allowed MACs ) Not used | |
778 | require_kx list of allowed key_exchange methods ) for | |
779 | require_proto list of allowed protocols ) OpenSSL | |
780 | ------------------------------------------------------ | |
059ec3d9 PH |
781 | |
782 | Returns: OK on success | |
783 | DEFER for errors before the start of the negotiation | |
784 | FAIL for errors during the negotation; the server can't | |
785 | continue running. | |
786 | */ | |
787 | ||
788 | int | |
83da1223 PH |
789 | tls_server_start(uschar *require_ciphers, uschar *require_mac, |
790 | uschar *require_kx, uschar *require_proto) | |
059ec3d9 PH |
791 | { |
792 | int rc; | |
793 | uschar *expciphers; | |
7be682ca | 794 | tls_ext_ctx_cb *cbinfo; |
059ec3d9 PH |
795 | |
796 | /* Check for previous activation */ | |
797 | ||
798 | if (tls_active >= 0) | |
799 | { | |
5ca6d115 | 800 | tls_error(US"STARTTLS received after TLS started", NULL, US""); |
059ec3d9 PH |
801 | smtp_printf("554 Already in TLS\r\n"); |
802 | return FAIL; | |
803 | } | |
804 | ||
805 | /* Initialize the SSL library. If it fails, it will already have logged | |
806 | the error. */ | |
807 | ||
808 | rc = tls_init(NULL, tls_dhparam, tls_certificate, tls_privatekey, NULL); | |
809 | if (rc != OK) return rc; | |
7be682ca | 810 | cbinfo = static_cbinfo; |
059ec3d9 PH |
811 | |
812 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers)) | |
813 | return FAIL; | |
814 | ||
815 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they | |
816 | are separated by underscores. So that I can use either form in my tests, and | |
817 | also for general convenience, we turn underscores into hyphens here. */ | |
818 | ||
819 | if (expciphers != NULL) | |
820 | { | |
821 | uschar *s = expciphers; | |
822 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } | |
823 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); | |
824 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) | |
7199e1ee | 825 | return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL); |
7be682ca | 826 | cbinfo->server_cipher_list = expciphers; |
059ec3d9 PH |
827 | } |
828 | ||
829 | /* If this is a host for which certificate verification is mandatory or | |
830 | optional, set up appropriately. */ | |
831 | ||
832 | tls_certificate_verified = FALSE; | |
833 | verify_callback_called = FALSE; | |
834 | ||
835 | if (verify_check_host(&tls_verify_hosts) == OK) | |
836 | { | |
7be682ca | 837 | rc = setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, FALSE); |
059ec3d9 PH |
838 | if (rc != OK) return rc; |
839 | verify_optional = FALSE; | |
840 | } | |
841 | else if (verify_check_host(&tls_try_verify_hosts) == OK) | |
842 | { | |
7be682ca | 843 | rc = setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, TRUE); |
059ec3d9 PH |
844 | if (rc != OK) return rc; |
845 | verify_optional = TRUE; | |
846 | } | |
847 | ||
848 | /* Prepare for new connection */ | |
849 | ||
7199e1ee | 850 | if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL); |
da3ad30d PP |
851 | |
852 | /* Warning: we used to SSL_clear(ssl) here, it was removed. | |
853 | * | |
854 | * With the SSL_clear(), we get strange interoperability bugs with | |
855 | * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in | |
856 | * OpenSSL itself, as a clear should not lead to inability to follow protocols. | |
857 | * | |
858 | * The SSL_clear() call is to let an existing SSL* be reused, typically after | |
859 | * session shutdown. In this case, we have a brand new object and there's no | |
860 | * obvious reason to immediately clear it. I'm guessing that this was | |
861 | * originally added because of incomplete initialisation which the clear fixed, | |
862 | * in some historic release. | |
863 | */ | |
059ec3d9 PH |
864 | |
865 | /* Set context and tell client to go ahead, except in the case of TLS startup | |
866 | on connection, where outputting anything now upsets the clients and tends to | |
867 | make them disconnect. We need to have an explicit fflush() here, to force out | |
868 | the response. Other smtp_printf() calls do not need it, because in non-TLS | |
869 | mode, the fflush() happens when smtp_getc() is called. */ | |
870 | ||
871 | SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx)); | |
872 | if (!tls_on_connect) | |
873 | { | |
874 | smtp_printf("220 TLS go ahead\r\n"); | |
875 | fflush(smtp_out); | |
876 | } | |
877 | ||
878 | /* Now negotiate the TLS session. We put our own timer on it, since it seems | |
879 | that the OpenSSL library doesn't. */ | |
880 | ||
56f5d9bd PH |
881 | SSL_set_wfd(ssl, fileno(smtp_out)); |
882 | SSL_set_rfd(ssl, fileno(smtp_in)); | |
059ec3d9 PH |
883 | SSL_set_accept_state(ssl); |
884 | ||
885 | DEBUG(D_tls) debug_printf("Calling SSL_accept\n"); | |
886 | ||
887 | sigalrm_seen = FALSE; | |
888 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
889 | rc = SSL_accept(ssl); | |
890 | alarm(0); | |
891 | ||
892 | if (rc <= 0) | |
893 | { | |
7199e1ee | 894 | tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL); |
77bb000f PP |
895 | if (ERR_get_error() == 0) |
896 | log_write(0, LOG_MAIN, | |
a053d125 | 897 | "TLS client disconnected cleanly (rejected our certificate?)"); |
059ec3d9 PH |
898 | return FAIL; |
899 | } | |
900 | ||
901 | DEBUG(D_tls) debug_printf("SSL_accept was successful\n"); | |
902 | ||
903 | /* TLS has been set up. Adjust the input functions to read via TLS, | |
904 | and initialize things. */ | |
905 | ||
906 | construct_cipher_name(ssl); | |
907 | ||
908 | DEBUG(D_tls) | |
909 | { | |
910 | uschar buf[2048]; | |
911 | if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)) != NULL) | |
912 | debug_printf("Shared ciphers: %s\n", buf); | |
913 | } | |
914 | ||
915 | ||
916 | ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size); | |
917 | ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0; | |
918 | ssl_xfer_eof = ssl_xfer_error = 0; | |
919 | ||
920 | receive_getc = tls_getc; | |
921 | receive_ungetc = tls_ungetc; | |
922 | receive_feof = tls_feof; | |
923 | receive_ferror = tls_ferror; | |
58eb016e | 924 | receive_smtp_buffered = tls_smtp_buffered; |
059ec3d9 PH |
925 | |
926 | tls_active = fileno(smtp_out); | |
927 | return OK; | |
928 | } | |
929 | ||
930 | ||
931 | ||
932 | ||
933 | ||
934 | /************************************************* | |
935 | * Start a TLS session in a client * | |
936 | *************************************************/ | |
937 | ||
938 | /* Called from the smtp transport after STARTTLS has been accepted. | |
939 | ||
940 | Argument: | |
941 | fd the fd of the connection | |
942 | host connected host (for messages) | |
83da1223 | 943 | addr the first address |
059ec3d9 PH |
944 | dhparam DH parameter file |
945 | certificate certificate file | |
946 | privatekey private key file | |
947 | verify_certs file for certificate verify | |
948 | crl file containing CRL | |
949 | require_ciphers list of allowed ciphers | |
83da1223 PH |
950 | ------------------------------------------------------ |
951 | require_mac list of allowed MACs ) Not used | |
952 | require_kx list of allowed key_exchange methods ) for | |
953 | require_proto list of allowed protocols ) OpenSSL | |
954 | ------------------------------------------------------ | |
955 | timeout startup timeout | |
059ec3d9 PH |
956 | |
957 | Returns: OK on success | |
958 | FAIL otherwise - note that tls_error() will not give DEFER | |
959 | because this is not a server | |
960 | */ | |
961 | ||
962 | int | |
963 | tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam, | |
964 | uschar *certificate, uschar *privatekey, uschar *verify_certs, uschar *crl, | |
83da1223 PH |
965 | uschar *require_ciphers, uschar *require_mac, uschar *require_kx, |
966 | uschar *require_proto, int timeout) | |
059ec3d9 PH |
967 | { |
968 | static uschar txt[256]; | |
969 | uschar *expciphers; | |
970 | X509* server_cert; | |
971 | int rc; | |
972 | ||
973 | rc = tls_init(host, dhparam, certificate, privatekey, addr); | |
974 | if (rc != OK) return rc; | |
975 | ||
976 | tls_certificate_verified = FALSE; | |
977 | verify_callback_called = FALSE; | |
978 | ||
979 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers)) | |
980 | return FAIL; | |
981 | ||
982 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they | |
983 | are separated by underscores. So that I can use either form in my tests, and | |
984 | also for general convenience, we turn underscores into hyphens here. */ | |
985 | ||
986 | if (expciphers != NULL) | |
987 | { | |
988 | uschar *s = expciphers; | |
989 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } | |
990 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); | |
991 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) | |
7199e1ee | 992 | return tls_error(US"SSL_CTX_set_cipher_list", host, NULL); |
059ec3d9 PH |
993 | } |
994 | ||
7be682ca | 995 | rc = setup_certs(ctx, verify_certs, crl, host, FALSE); |
059ec3d9 PH |
996 | if (rc != OK) return rc; |
997 | ||
7199e1ee | 998 | if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", host, NULL); |
059ec3d9 PH |
999 | SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx)); |
1000 | SSL_set_fd(ssl, fd); | |
1001 | SSL_set_connect_state(ssl); | |
1002 | ||
1003 | /* There doesn't seem to be a built-in timeout on connection. */ | |
1004 | ||
1005 | DEBUG(D_tls) debug_printf("Calling SSL_connect\n"); | |
1006 | sigalrm_seen = FALSE; | |
1007 | alarm(timeout); | |
1008 | rc = SSL_connect(ssl); | |
1009 | alarm(0); | |
1010 | ||
1011 | if (rc <= 0) | |
7199e1ee | 1012 | return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL); |
059ec3d9 PH |
1013 | |
1014 | DEBUG(D_tls) debug_printf("SSL_connect succeeded\n"); | |
1015 | ||
453a6645 | 1016 | /* Beware anonymous ciphers which lead to server_cert being NULL */ |
059ec3d9 | 1017 | server_cert = SSL_get_peer_certificate (ssl); |
453a6645 PP |
1018 | if (server_cert) |
1019 | { | |
1020 | tls_peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert), | |
1021 | CS txt, sizeof(txt)); | |
1022 | tls_peerdn = txt; | |
1023 | } | |
1024 | else | |
1025 | tls_peerdn = NULL; | |
059ec3d9 PH |
1026 | |
1027 | construct_cipher_name(ssl); /* Sets tls_cipher */ | |
1028 | ||
1029 | tls_active = fd; | |
1030 | return OK; | |
1031 | } | |
1032 | ||
1033 | ||
1034 | ||
1035 | ||
1036 | ||
1037 | /************************************************* | |
1038 | * TLS version of getc * | |
1039 | *************************************************/ | |
1040 | ||
1041 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, | |
1042 | it refills the buffer via the SSL reading function. | |
1043 | ||
1044 | Arguments: none | |
1045 | Returns: the next character or EOF | |
1046 | */ | |
1047 | ||
1048 | int | |
1049 | tls_getc(void) | |
1050 | { | |
1051 | if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm) | |
1052 | { | |
1053 | int error; | |
1054 | int inbytes; | |
1055 | ||
c80c5570 PP |
1056 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl, |
1057 | ssl_xfer_buffer, ssl_xfer_buffer_size); | |
059ec3d9 PH |
1058 | |
1059 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
1060 | inbytes = SSL_read(ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size); | |
1061 | error = SSL_get_error(ssl, inbytes); | |
1062 | alarm(0); | |
1063 | ||
1064 | /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been | |
1065 | closed down, not that the socket itself has been closed down. Revert to | |
1066 | non-SSL handling. */ | |
1067 | ||
1068 | if (error == SSL_ERROR_ZERO_RETURN) | |
1069 | { | |
1070 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); | |
1071 | ||
1072 | receive_getc = smtp_getc; | |
1073 | receive_ungetc = smtp_ungetc; | |
1074 | receive_feof = smtp_feof; | |
1075 | receive_ferror = smtp_ferror; | |
58eb016e | 1076 | receive_smtp_buffered = smtp_buffered; |
059ec3d9 PH |
1077 | |
1078 | SSL_free(ssl); | |
1079 | ssl = NULL; | |
1080 | tls_active = -1; | |
1081 | tls_cipher = NULL; | |
1082 | tls_peerdn = NULL; | |
1083 | ||
1084 | return smtp_getc(); | |
1085 | } | |
1086 | ||
1087 | /* Handle genuine errors */ | |
1088 | ||
ba084640 PP |
1089 | else if (error == SSL_ERROR_SSL) |
1090 | { | |
1091 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
89dd51cd | 1092 | log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring); |
ba084640 PP |
1093 | ssl_xfer_error = 1; |
1094 | return EOF; | |
1095 | } | |
1096 | ||
059ec3d9 PH |
1097 | else if (error != SSL_ERROR_NONE) |
1098 | { | |
1099 | DEBUG(D_tls) debug_printf("Got SSL error %d\n", error); | |
1100 | ssl_xfer_error = 1; | |
1101 | return EOF; | |
1102 | } | |
c80c5570 | 1103 | |
80a47a2c TK |
1104 | #ifndef DISABLE_DKIM |
1105 | dkim_exim_verify_feed(ssl_xfer_buffer, inbytes); | |
1106 | #endif | |
059ec3d9 PH |
1107 | ssl_xfer_buffer_hwm = inbytes; |
1108 | ssl_xfer_buffer_lwm = 0; | |
1109 | } | |
1110 | ||
1111 | /* Something in the buffer; return next uschar */ | |
1112 | ||
1113 | return ssl_xfer_buffer[ssl_xfer_buffer_lwm++]; | |
1114 | } | |
1115 | ||
1116 | ||
1117 | ||
1118 | /************************************************* | |
1119 | * Read bytes from TLS channel * | |
1120 | *************************************************/ | |
1121 | ||
1122 | /* | |
1123 | Arguments: | |
1124 | buff buffer of data | |
1125 | len size of buffer | |
1126 | ||
1127 | Returns: the number of bytes read | |
1128 | -1 after a failed read | |
1129 | */ | |
1130 | ||
1131 | int | |
1132 | tls_read(uschar *buff, size_t len) | |
1133 | { | |
1134 | int inbytes; | |
1135 | int error; | |
1136 | ||
c80c5570 PP |
1137 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl, |
1138 | buff, (unsigned int)len); | |
059ec3d9 PH |
1139 | |
1140 | inbytes = SSL_read(ssl, CS buff, len); | |
1141 | error = SSL_get_error(ssl, inbytes); | |
1142 | ||
1143 | if (error == SSL_ERROR_ZERO_RETURN) | |
1144 | { | |
1145 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); | |
1146 | return -1; | |
1147 | } | |
1148 | else if (error != SSL_ERROR_NONE) | |
1149 | { | |
1150 | return -1; | |
1151 | } | |
1152 | ||
1153 | return inbytes; | |
1154 | } | |
1155 | ||
1156 | ||
1157 | ||
1158 | ||
1159 | ||
1160 | /************************************************* | |
1161 | * Write bytes down TLS channel * | |
1162 | *************************************************/ | |
1163 | ||
1164 | /* | |
1165 | Arguments: | |
1166 | buff buffer of data | |
1167 | len number of bytes | |
1168 | ||
1169 | Returns: the number of bytes after a successful write, | |
1170 | -1 after a failed write | |
1171 | */ | |
1172 | ||
1173 | int | |
1174 | tls_write(const uschar *buff, size_t len) | |
1175 | { | |
1176 | int outbytes; | |
1177 | int error; | |
1178 | int left = len; | |
1179 | ||
c80c5570 | 1180 | DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left); |
059ec3d9 PH |
1181 | while (left > 0) |
1182 | { | |
c80c5570 | 1183 | DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left); |
059ec3d9 PH |
1184 | outbytes = SSL_write(ssl, CS buff, left); |
1185 | error = SSL_get_error(ssl, outbytes); | |
1186 | DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error); | |
1187 | switch (error) | |
1188 | { | |
1189 | case SSL_ERROR_SSL: | |
1190 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
1191 | log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring); | |
1192 | return -1; | |
1193 | ||
1194 | case SSL_ERROR_NONE: | |
1195 | left -= outbytes; | |
1196 | buff += outbytes; | |
1197 | break; | |
1198 | ||
1199 | case SSL_ERROR_ZERO_RETURN: | |
1200 | log_write(0, LOG_MAIN, "SSL channel closed on write"); | |
1201 | return -1; | |
1202 | ||
1203 | default: | |
1204 | log_write(0, LOG_MAIN, "SSL_write error %d", error); | |
1205 | return -1; | |
1206 | } | |
1207 | } | |
1208 | return len; | |
1209 | } | |
1210 | ||
1211 | ||
1212 | ||
1213 | /************************************************* | |
1214 | * Close down a TLS session * | |
1215 | *************************************************/ | |
1216 | ||
1217 | /* This is also called from within a delivery subprocess forked from the | |
1218 | daemon, to shut down the TLS library, without actually doing a shutdown (which | |
1219 | would tamper with the SSL session in the parent process). | |
1220 | ||
1221 | Arguments: TRUE if SSL_shutdown is to be called | |
1222 | Returns: nothing | |
1223 | */ | |
1224 | ||
1225 | void | |
1226 | tls_close(BOOL shutdown) | |
1227 | { | |
1228 | if (tls_active < 0) return; /* TLS was not active */ | |
1229 | ||
1230 | if (shutdown) | |
1231 | { | |
1232 | DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n"); | |
1233 | SSL_shutdown(ssl); | |
1234 | } | |
1235 | ||
1236 | SSL_free(ssl); | |
1237 | ssl = NULL; | |
1238 | ||
1239 | tls_active = -1; | |
1240 | } | |
1241 | ||
36f12725 NM |
1242 | |
1243 | ||
1244 | ||
1245 | /************************************************* | |
1246 | * Report the library versions. * | |
1247 | *************************************************/ | |
1248 | ||
1249 | /* There have historically been some issues with binary compatibility in | |
1250 | OpenSSL libraries; if Exim (like many other applications) is built against | |
1251 | one version of OpenSSL but the run-time linker picks up another version, | |
1252 | it can result in serious failures, including crashing with a SIGSEGV. So | |
1253 | report the version found by the compiler and the run-time version. | |
1254 | ||
1255 | Arguments: a FILE* to print the results to | |
1256 | Returns: nothing | |
1257 | */ | |
1258 | ||
1259 | void | |
1260 | tls_version_report(FILE *f) | |
1261 | { | |
754a0503 PP |
1262 | fprintf(f, "Library version: OpenSSL: Compile: %s\n" |
1263 | " Runtime: %s\n", | |
1264 | OPENSSL_VERSION_TEXT, | |
1265 | SSLeay_version(SSLEAY_VERSION)); | |
36f12725 NM |
1266 | } |
1267 | ||
9e3331ea TK |
1268 | |
1269 | ||
1270 | ||
1271 | /************************************************* | |
1272 | * Pseudo-random number generation * | |
1273 | *************************************************/ | |
1274 | ||
1275 | /* Pseudo-random number generation. The result is not expected to be | |
1276 | cryptographically strong but not so weak that someone will shoot themselves | |
1277 | in the foot using it as a nonce in input in some email header scheme or | |
1278 | whatever weirdness they'll twist this into. The result should handle fork() | |
1279 | and avoid repeating sequences. OpenSSL handles that for us. | |
1280 | ||
1281 | Arguments: | |
1282 | max range maximum | |
1283 | Returns a random number in range [0, max-1] | |
1284 | */ | |
1285 | ||
1286 | int | |
1287 | pseudo_random_number(int max) | |
1288 | { | |
1289 | unsigned int r; | |
1290 | int i, needed_len; | |
1291 | uschar *p; | |
1292 | uschar smallbuf[sizeof(r)]; | |
1293 | ||
1294 | if (max <= 1) | |
1295 | return 0; | |
1296 | ||
1297 | /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */ | |
1298 | if (!RAND_status()) | |
1299 | { | |
1300 | randstuff r; | |
1301 | gettimeofday(&r.tv, NULL); | |
1302 | r.p = getpid(); | |
1303 | ||
1304 | RAND_seed((uschar *)(&r), sizeof(r)); | |
1305 | } | |
1306 | /* We're after pseudo-random, not random; if we still don't have enough data | |
1307 | in the internal PRNG then our options are limited. We could sleep and hope | |
1308 | for entropy to come along (prayer technique) but if the system is so depleted | |
1309 | in the first place then something is likely to just keep taking it. Instead, | |
1310 | we'll just take whatever little bit of pseudo-random we can still manage to | |
1311 | get. */ | |
1312 | ||
1313 | needed_len = sizeof(r); | |
1314 | /* Don't take 8 times more entropy than needed if int is 8 octets and we were | |
1315 | asked for a number less than 10. */ | |
1316 | for (r = max, i = 0; r; ++i) | |
1317 | r >>= 1; | |
1318 | i = (i + 7) / 8; | |
1319 | if (i < needed_len) | |
1320 | needed_len = i; | |
1321 | ||
1322 | /* We do not care if crypto-strong */ | |
1323 | (void) RAND_pseudo_bytes(smallbuf, needed_len); | |
1324 | r = 0; | |
1325 | for (p = smallbuf; needed_len; --needed_len, ++p) | |
1326 | { | |
1327 | r *= 256; | |
1328 | r += *p; | |
1329 | } | |
1330 | ||
1331 | /* We don't particularly care about weighted results; if someone wants | |
1332 | smooth distribution and cares enough then they should submit a patch then. */ | |
1333 | return r % max; | |
1334 | } | |
1335 | ||
77bb000f PP |
1336 | |
1337 | ||
1338 | ||
1339 | /************************************************* | |
1340 | * OpenSSL option parse * | |
1341 | *************************************************/ | |
1342 | ||
1343 | /* Parse one option for tls_openssl_options_parse below | |
1344 | ||
1345 | Arguments: | |
1346 | name one option name | |
1347 | value place to store a value for it | |
1348 | Returns success or failure in parsing | |
1349 | */ | |
1350 | ||
1351 | struct exim_openssl_option { | |
1352 | uschar *name; | |
1353 | long value; | |
1354 | }; | |
1355 | /* We could use a macro to expand, but we need the ifdef and not all the | |
1356 | options document which version they were introduced in. Policylet: include | |
1357 | all options unless explicitly for DTLS, let the administrator choose which | |
1358 | to apply. | |
1359 | ||
1360 | This list is current as of: | |
c80c5570 | 1361 | ==> 1.0.1b <== */ |
77bb000f PP |
1362 | static struct exim_openssl_option exim_openssl_options[] = { |
1363 | /* KEEP SORTED ALPHABETICALLY! */ | |
1364 | #ifdef SSL_OP_ALL | |
73a46702 | 1365 | { US"all", SSL_OP_ALL }, |
77bb000f PP |
1366 | #endif |
1367 | #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION | |
73a46702 | 1368 | { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION }, |
77bb000f PP |
1369 | #endif |
1370 | #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE | |
73a46702 | 1371 | { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE }, |
77bb000f PP |
1372 | #endif |
1373 | #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS | |
73a46702 | 1374 | { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS }, |
77bb000f PP |
1375 | #endif |
1376 | #ifdef SSL_OP_EPHEMERAL_RSA | |
73a46702 | 1377 | { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA }, |
77bb000f PP |
1378 | #endif |
1379 | #ifdef SSL_OP_LEGACY_SERVER_CONNECT | |
73a46702 | 1380 | { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT }, |
77bb000f PP |
1381 | #endif |
1382 | #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER | |
73a46702 | 1383 | { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER }, |
77bb000f PP |
1384 | #endif |
1385 | #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG | |
73a46702 | 1386 | { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG }, |
77bb000f PP |
1387 | #endif |
1388 | #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING | |
73a46702 | 1389 | { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING }, |
77bb000f PP |
1390 | #endif |
1391 | #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG | |
73a46702 | 1392 | { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG }, |
77bb000f PP |
1393 | #endif |
1394 | #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG | |
73a46702 | 1395 | { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG }, |
77bb000f | 1396 | #endif |
c80c5570 PP |
1397 | #ifdef SSL_OP_NO_COMPRESSION |
1398 | { US"no_compression", SSL_OP_NO_COMPRESSION }, | |
1399 | #endif | |
77bb000f | 1400 | #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION |
73a46702 | 1401 | { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION }, |
77bb000f | 1402 | #endif |
c0c7b2da PP |
1403 | #ifdef SSL_OP_NO_SSLv2 |
1404 | { US"no_sslv2", SSL_OP_NO_SSLv2 }, | |
1405 | #endif | |
1406 | #ifdef SSL_OP_NO_SSLv3 | |
1407 | { US"no_sslv3", SSL_OP_NO_SSLv3 }, | |
1408 | #endif | |
1409 | #ifdef SSL_OP_NO_TICKET | |
1410 | { US"no_ticket", SSL_OP_NO_TICKET }, | |
1411 | #endif | |
1412 | #ifdef SSL_OP_NO_TLSv1 | |
1413 | { US"no_tlsv1", SSL_OP_NO_TLSv1 }, | |
1414 | #endif | |
c80c5570 PP |
1415 | #ifdef SSL_OP_NO_TLSv1_1 |
1416 | #if SSL_OP_NO_TLSv1_1 == 0x00000400L | |
1417 | /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */ | |
1418 | #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring | |
1419 | #else | |
1420 | { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 }, | |
1421 | #endif | |
1422 | #endif | |
1423 | #ifdef SSL_OP_NO_TLSv1_2 | |
1424 | { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 }, | |
1425 | #endif | |
77bb000f | 1426 | #ifdef SSL_OP_SINGLE_DH_USE |
73a46702 | 1427 | { US"single_dh_use", SSL_OP_SINGLE_DH_USE }, |
77bb000f PP |
1428 | #endif |
1429 | #ifdef SSL_OP_SINGLE_ECDH_USE | |
73a46702 | 1430 | { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE }, |
77bb000f PP |
1431 | #endif |
1432 | #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG | |
73a46702 | 1433 | { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG }, |
77bb000f PP |
1434 | #endif |
1435 | #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG | |
73a46702 | 1436 | { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG }, |
77bb000f PP |
1437 | #endif |
1438 | #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG | |
73a46702 | 1439 | { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG }, |
77bb000f PP |
1440 | #endif |
1441 | #ifdef SSL_OP_TLS_D5_BUG | |
73a46702 | 1442 | { US"tls_d5_bug", SSL_OP_TLS_D5_BUG }, |
77bb000f PP |
1443 | #endif |
1444 | #ifdef SSL_OP_TLS_ROLLBACK_BUG | |
73a46702 | 1445 | { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG }, |
77bb000f PP |
1446 | #endif |
1447 | }; | |
1448 | static int exim_openssl_options_size = | |
1449 | sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option); | |
1450 | ||
c80c5570 | 1451 | |
77bb000f PP |
1452 | static BOOL |
1453 | tls_openssl_one_option_parse(uschar *name, long *value) | |
1454 | { | |
1455 | int first = 0; | |
1456 | int last = exim_openssl_options_size; | |
1457 | while (last > first) | |
1458 | { | |
1459 | int middle = (first + last)/2; | |
1460 | int c = Ustrcmp(name, exim_openssl_options[middle].name); | |
1461 | if (c == 0) | |
1462 | { | |
1463 | *value = exim_openssl_options[middle].value; | |
1464 | return TRUE; | |
1465 | } | |
1466 | else if (c > 0) | |
1467 | first = middle + 1; | |
1468 | else | |
1469 | last = middle; | |
1470 | } | |
1471 | return FALSE; | |
1472 | } | |
1473 | ||
1474 | ||
1475 | ||
1476 | ||
1477 | /************************************************* | |
1478 | * OpenSSL option parsing logic * | |
1479 | *************************************************/ | |
1480 | ||
1481 | /* OpenSSL has a number of compatibility options which an administrator might | |
1482 | reasonably wish to set. Interpret a list similarly to decode_bits(), so that | |
1483 | we look like log_selector. | |
1484 | ||
1485 | Arguments: | |
1486 | option_spec the administrator-supplied string of options | |
1487 | results ptr to long storage for the options bitmap | |
1488 | Returns success or failure | |
1489 | */ | |
1490 | ||
1491 | BOOL | |
1492 | tls_openssl_options_parse(uschar *option_spec, long *results) | |
1493 | { | |
1494 | long result, item; | |
1495 | uschar *s, *end; | |
1496 | uschar keep_c; | |
1497 | BOOL adding, item_parsed; | |
1498 | ||
0e944a0d | 1499 | result = 0L; |
da3ad30d PP |
1500 | /* Prior to 4.78 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed |
1501 | * from default because it increases BEAST susceptibility. */ | |
77bb000f PP |
1502 | |
1503 | if (option_spec == NULL) | |
1504 | { | |
1505 | *results = result; | |
1506 | return TRUE; | |
1507 | } | |
1508 | ||
1509 | for (s=option_spec; *s != '\0'; /**/) | |
1510 | { | |
1511 | while (isspace(*s)) ++s; | |
1512 | if (*s == '\0') | |
1513 | break; | |
1514 | if (*s != '+' && *s != '-') | |
1515 | { | |
1516 | DEBUG(D_tls) debug_printf("malformed openssl option setting: " | |
0e944a0d | 1517 | "+ or - expected but found \"%s\"\n", s); |
77bb000f PP |
1518 | return FALSE; |
1519 | } | |
1520 | adding = *s++ == '+'; | |
1521 | for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ; | |
1522 | keep_c = *end; | |
1523 | *end = '\0'; | |
1524 | item_parsed = tls_openssl_one_option_parse(s, &item); | |
1525 | if (!item_parsed) | |
1526 | { | |
0e944a0d | 1527 | DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s); |
77bb000f PP |
1528 | return FALSE; |
1529 | } | |
1530 | DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n", | |
1531 | adding ? "adding" : "removing", result, item, s); | |
1532 | if (adding) | |
1533 | result |= item; | |
1534 | else | |
1535 | result &= ~item; | |
1536 | *end = keep_c; | |
1537 | s = end; | |
1538 | } | |
1539 | ||
1540 | *results = result; | |
1541 | return TRUE; | |
1542 | } | |
1543 | ||
059ec3d9 | 1544 | /* End of tls-openssl.c */ |