Commit | Line | Data |
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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; | |
3f0945ff | 388 | int old_pool = store_pool; |
7be682ca PP |
389 | |
390 | if (!servername) | |
391 | return SSL_TLSEXT_ERR_OK; | |
392 | ||
3f0945ff | 393 | DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername, |
7be682ca PP |
394 | reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)"); |
395 | ||
396 | /* Make the extension value available for expansion */ | |
3f0945ff PP |
397 | store_pool = POOL_PERM; |
398 | tls_sni = string_copy(US servername); | |
399 | store_pool = old_pool; | |
7be682ca PP |
400 | |
401 | if (!reexpand_tls_files_for_sni) | |
402 | return SSL_TLSEXT_ERR_OK; | |
403 | ||
404 | /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually; | |
405 | not confident that memcpy wouldn't break some internal reference counting. | |
406 | Especially since there's a references struct member, which would be off. */ | |
407 | ||
408 | ctx_sni = SSL_CTX_new(SSLv23_server_method()); | |
409 | if (!ctx_sni) | |
410 | { | |
411 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
412 | DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring); | |
413 | return SSL_TLSEXT_ERR_NOACK; | |
414 | } | |
415 | ||
416 | /* Not sure how many of these are actually needed, since SSL object | |
417 | already exists. Might even need this selfsame callback, for reneg? */ | |
418 | ||
419 | SSL_CTX_set_info_callback(ctx_sni, SSL_CTX_get_info_callback(ctx)); | |
420 | SSL_CTX_set_mode(ctx_sni, SSL_CTX_get_mode(ctx)); | |
421 | SSL_CTX_set_options(ctx_sni, SSL_CTX_get_options(ctx)); | |
422 | SSL_CTX_set_timeout(ctx_sni, SSL_CTX_get_timeout(ctx)); | |
423 | SSL_CTX_set_tlsext_servername_callback(ctx_sni, tls_servername_cb); | |
424 | SSL_CTX_set_tlsext_servername_arg(ctx_sni, cbinfo); | |
425 | if (cbinfo->server_cipher_list) | |
426 | SSL_CTX_set_cipher_list(ctx_sni, CS cbinfo->server_cipher_list); | |
427 | ||
428 | rc = tls_expand_session_files(ctx_sni, cbinfo); | |
429 | if (rc != OK) return SSL_TLSEXT_ERR_NOACK; | |
430 | ||
431 | rc = setup_certs(ctx_sni, tls_verify_certificates, tls_crl, NULL, FALSE); | |
432 | if (rc != OK) return SSL_TLSEXT_ERR_NOACK; | |
433 | ||
434 | DEBUG(D_tls) debug_printf("Switching SSL context.\n"); | |
435 | SSL_set_SSL_CTX(s, ctx_sni); | |
436 | ||
437 | return SSL_TLSEXT_ERR_OK; | |
438 | } | |
439 | ||
440 | ||
441 | ||
442 | ||
059ec3d9 PH |
443 | /************************************************* |
444 | * Initialize for TLS * | |
445 | *************************************************/ | |
446 | ||
447 | /* Called from both server and client code, to do preliminary initialization of | |
448 | the library. | |
449 | ||
450 | Arguments: | |
451 | host connected host, if client; NULL if server | |
452 | dhparam DH parameter file | |
453 | certificate certificate file | |
454 | privatekey private key | |
455 | addr address if client; NULL if server (for some randomness) | |
456 | ||
457 | Returns: OK/DEFER/FAIL | |
458 | */ | |
459 | ||
460 | static int | |
c91535f3 PH |
461 | tls_init(host_item *host, uschar *dhparam, uschar *certificate, |
462 | uschar *privatekey, address_item *addr) | |
059ec3d9 | 463 | { |
77bb000f | 464 | long init_options; |
7be682ca | 465 | int rc; |
77bb000f | 466 | BOOL okay; |
7be682ca PP |
467 | tls_ext_ctx_cb *cbinfo; |
468 | ||
469 | cbinfo = store_malloc(sizeof(tls_ext_ctx_cb)); | |
470 | cbinfo->certificate = certificate; | |
471 | cbinfo->privatekey = privatekey; | |
472 | cbinfo->dhparam = dhparam; | |
473 | cbinfo->host = host; | |
77bb000f | 474 | |
059ec3d9 PH |
475 | SSL_load_error_strings(); /* basic set up */ |
476 | OpenSSL_add_ssl_algorithms(); | |
477 | ||
388d6564 | 478 | #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256) |
77bb000f | 479 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the |
a0475b69 TK |
480 | list of available digests. */ |
481 | EVP_add_digest(EVP_sha256()); | |
cf1ef1a9 | 482 | #endif |
a0475b69 | 483 | |
059ec3d9 PH |
484 | /* Create a context */ |
485 | ||
486 | ctx = SSL_CTX_new((host == NULL)? | |
487 | SSLv23_server_method() : SSLv23_client_method()); | |
488 | ||
7199e1ee | 489 | if (ctx == NULL) return tls_error(US"SSL_CTX_new", host, NULL); |
059ec3d9 PH |
490 | |
491 | /* It turns out that we need to seed the random number generator this early in | |
492 | order to get the full complement of ciphers to work. It took me roughly a day | |
493 | of work to discover this by experiment. | |
494 | ||
495 | On systems that have /dev/urandom, SSL may automatically seed itself from | |
496 | there. Otherwise, we have to make something up as best we can. Double check | |
497 | afterwards. */ | |
498 | ||
499 | if (!RAND_status()) | |
500 | { | |
501 | randstuff r; | |
9e3331ea | 502 | gettimeofday(&r.tv, NULL); |
059ec3d9 PH |
503 | r.p = getpid(); |
504 | ||
505 | RAND_seed((uschar *)(&r), sizeof(r)); | |
506 | RAND_seed((uschar *)big_buffer, big_buffer_size); | |
507 | if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr)); | |
508 | ||
509 | if (!RAND_status()) | |
7199e1ee | 510 | return tls_error(US"RAND_status", host, |
5ca6d115 | 511 | US"unable to seed random number generator"); |
059ec3d9 PH |
512 | } |
513 | ||
514 | /* Set up the information callback, which outputs if debugging is at a suitable | |
515 | level. */ | |
516 | ||
58c01c94 | 517 | SSL_CTX_set_info_callback(ctx, (void (*)())info_callback); |
059ec3d9 | 518 | |
c80c5570 PP |
519 | /* Automatically re-try reads/writes after renegotiation. */ |
520 | (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY); | |
521 | ||
77bb000f PP |
522 | /* Apply administrator-supplied work-arounds. |
523 | Historically we applied just one requested option, | |
524 | SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we | |
525 | moved to an administrator-controlled list of options to specify and | |
526 | grandfathered in the first one as the default value for "openssl_options". | |
059ec3d9 | 527 | |
77bb000f PP |
528 | No OpenSSL version number checks: the options we accept depend upon the |
529 | availability of the option value macros from OpenSSL. */ | |
059ec3d9 | 530 | |
77bb000f PP |
531 | okay = tls_openssl_options_parse(openssl_options, &init_options); |
532 | if (!okay) | |
73a46702 | 533 | return tls_error(US"openssl_options parsing failed", host, NULL); |
77bb000f PP |
534 | |
535 | if (init_options) | |
536 | { | |
537 | DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options); | |
538 | if (!(SSL_CTX_set_options(ctx, init_options))) | |
539 | return tls_error(string_sprintf( | |
540 | "SSL_CTX_set_option(%#lx)", init_options), host, NULL); | |
541 | } | |
542 | else | |
543 | DEBUG(D_tls) debug_printf("no SSL CTX options to set\n"); | |
059ec3d9 PH |
544 | |
545 | /* Initialize with DH parameters if supplied */ | |
546 | ||
7199e1ee | 547 | if (!init_dh(dhparam, host)) return DEFER; |
059ec3d9 PH |
548 | |
549 | /* Set up certificate and key */ | |
550 | ||
7be682ca PP |
551 | rc = tls_expand_session_files(ctx, cbinfo); |
552 | if (rc != OK) return rc; | |
c91535f3 | 553 | |
7be682ca PP |
554 | /* If we need to handle SNI, do so */ |
555 | #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT) | |
3f0945ff PP |
556 | if (host == NULL) |
557 | { | |
558 | /* We always do this, so that $tls_sni is available even if not used in | |
559 | tls_certificate */ | |
560 | SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb); | |
561 | SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo); | |
562 | } | |
7be682ca | 563 | #endif |
059ec3d9 PH |
564 | |
565 | /* Set up the RSA callback */ | |
566 | ||
567 | SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback); | |
568 | ||
569 | /* Finally, set the timeout, and we are done */ | |
570 | ||
571 | SSL_CTX_set_timeout(ctx, ssl_session_timeout); | |
572 | DEBUG(D_tls) debug_printf("Initialized TLS\n"); | |
7be682ca PP |
573 | |
574 | static_cbinfo = cbinfo; | |
575 | ||
059ec3d9 PH |
576 | return OK; |
577 | } | |
578 | ||
579 | ||
580 | ||
581 | ||
582 | /************************************************* | |
583 | * Get name of cipher in use * | |
584 | *************************************************/ | |
585 | ||
586 | /* The answer is left in a static buffer, and tls_cipher is set to point | |
587 | to it. | |
588 | ||
589 | Argument: pointer to an SSL structure for the connection | |
590 | Returns: nothing | |
591 | */ | |
592 | ||
593 | static void | |
594 | construct_cipher_name(SSL *ssl) | |
595 | { | |
596 | static uschar cipherbuf[256]; | |
57b3a7f5 PP |
597 | /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't |
598 | yet reflect that. It should be a safe change anyway, even 0.9.8 versions have | |
599 | the accessor functions use const in the prototype. */ | |
600 | const SSL_CIPHER *c; | |
059ec3d9 | 601 | uschar *ver; |
059ec3d9 PH |
602 | |
603 | switch (ssl->session->ssl_version) | |
604 | { | |
605 | case SSL2_VERSION: | |
606 | ver = US"SSLv2"; | |
607 | break; | |
608 | ||
609 | case SSL3_VERSION: | |
610 | ver = US"SSLv3"; | |
611 | break; | |
612 | ||
613 | case TLS1_VERSION: | |
614 | ver = US"TLSv1"; | |
615 | break; | |
616 | ||
c80c5570 PP |
617 | #ifdef TLS1_1_VERSION |
618 | case TLS1_1_VERSION: | |
619 | ver = US"TLSv1.1"; | |
620 | break; | |
621 | #endif | |
622 | ||
623 | #ifdef TLS1_2_VERSION | |
624 | case TLS1_2_VERSION: | |
625 | ver = US"TLSv1.2"; | |
626 | break; | |
627 | #endif | |
628 | ||
059ec3d9 PH |
629 | default: |
630 | ver = US"UNKNOWN"; | |
631 | } | |
632 | ||
57b3a7f5 | 633 | c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl); |
edc33b5f | 634 | SSL_CIPHER_get_bits(c, &tls_bits); |
059ec3d9 PH |
635 | |
636 | string_format(cipherbuf, sizeof(cipherbuf), "%s:%s:%u", ver, | |
edc33b5f | 637 | SSL_CIPHER_get_name(c), tls_bits); |
059ec3d9 PH |
638 | tls_cipher = cipherbuf; |
639 | ||
640 | DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf); | |
641 | } | |
642 | ||
643 | ||
644 | ||
645 | ||
646 | ||
647 | /************************************************* | |
648 | * Set up for verifying certificates * | |
649 | *************************************************/ | |
650 | ||
651 | /* Called by both client and server startup | |
652 | ||
653 | Arguments: | |
7be682ca | 654 | sctx SSL_CTX* to initialise |
059ec3d9 PH |
655 | certs certs file or NULL |
656 | crl CRL file or NULL | |
657 | host NULL in a server; the remote host in a client | |
658 | optional TRUE if called from a server for a host in tls_try_verify_hosts; | |
659 | otherwise passed as FALSE | |
660 | ||
661 | Returns: OK/DEFER/FAIL | |
662 | */ | |
663 | ||
664 | static int | |
7be682ca | 665 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional) |
059ec3d9 PH |
666 | { |
667 | uschar *expcerts, *expcrl; | |
668 | ||
669 | if (!expand_check(certs, US"tls_verify_certificates", &expcerts)) | |
670 | return DEFER; | |
671 | ||
672 | if (expcerts != NULL) | |
673 | { | |
674 | struct stat statbuf; | |
7be682ca | 675 | if (!SSL_CTX_set_default_verify_paths(sctx)) |
7199e1ee | 676 | return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL); |
059ec3d9 PH |
677 | |
678 | if (Ustat(expcerts, &statbuf) < 0) | |
679 | { | |
680 | log_write(0, LOG_MAIN|LOG_PANIC, | |
681 | "failed to stat %s for certificates", expcerts); | |
682 | return DEFER; | |
683 | } | |
684 | else | |
685 | { | |
686 | uschar *file, *dir; | |
687 | if ((statbuf.st_mode & S_IFMT) == S_IFDIR) | |
688 | { file = NULL; dir = expcerts; } | |
689 | else | |
690 | { file = expcerts; dir = NULL; } | |
691 | ||
692 | /* If a certificate file is empty, the next function fails with an | |
693 | unhelpful error message. If we skip it, we get the correct behaviour (no | |
694 | certificates are recognized, but the error message is still misleading (it | |
695 | says no certificate was supplied.) But this is better. */ | |
696 | ||
697 | if ((file == NULL || statbuf.st_size > 0) && | |
7be682ca | 698 | !SSL_CTX_load_verify_locations(sctx, CS file, CS dir)) |
7199e1ee | 699 | return tls_error(US"SSL_CTX_load_verify_locations", host, NULL); |
059ec3d9 PH |
700 | |
701 | if (file != NULL) | |
702 | { | |
7be682ca | 703 | SSL_CTX_set_client_CA_list(sctx, SSL_load_client_CA_file(CS file)); |
059ec3d9 PH |
704 | } |
705 | } | |
706 | ||
707 | /* Handle a certificate revocation list. */ | |
708 | ||
709 | #if OPENSSL_VERSION_NUMBER > 0x00907000L | |
710 | ||
8b417f2c PH |
711 | /* This bit of code is now the version supplied by Lars Mainka. (I have |
712 | * merely reformatted it into the Exim code style.) | |
713 | ||
714 | * "From here I changed the code to add support for multiple crl's | |
715 | * in pem format in one file or to support hashed directory entries in | |
716 | * pem format instead of a file. This method now uses the library function | |
717 | * X509_STORE_load_locations to add the CRL location to the SSL context. | |
718 | * OpenSSL will then handle the verify against CA certs and CRLs by | |
719 | * itself in the verify callback." */ | |
720 | ||
059ec3d9 PH |
721 | if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER; |
722 | if (expcrl != NULL && *expcrl != 0) | |
723 | { | |
8b417f2c PH |
724 | struct stat statbufcrl; |
725 | if (Ustat(expcrl, &statbufcrl) < 0) | |
726 | { | |
727 | log_write(0, LOG_MAIN|LOG_PANIC, | |
728 | "failed to stat %s for certificates revocation lists", expcrl); | |
729 | return DEFER; | |
730 | } | |
731 | else | |
059ec3d9 | 732 | { |
8b417f2c PH |
733 | /* is it a file or directory? */ |
734 | uschar *file, *dir; | |
7be682ca | 735 | X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx); |
8b417f2c | 736 | if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR) |
059ec3d9 | 737 | { |
8b417f2c PH |
738 | file = NULL; |
739 | dir = expcrl; | |
740 | DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir); | |
059ec3d9 PH |
741 | } |
742 | else | |
743 | { | |
8b417f2c PH |
744 | file = expcrl; |
745 | dir = NULL; | |
746 | DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file); | |
059ec3d9 | 747 | } |
8b417f2c | 748 | if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0) |
7199e1ee | 749 | return tls_error(US"X509_STORE_load_locations", host, NULL); |
8b417f2c PH |
750 | |
751 | /* setting the flags to check against the complete crl chain */ | |
752 | ||
753 | X509_STORE_set_flags(cvstore, | |
754 | X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL); | |
059ec3d9 | 755 | } |
059ec3d9 PH |
756 | } |
757 | ||
758 | #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */ | |
759 | ||
760 | /* If verification is optional, don't fail if no certificate */ | |
761 | ||
7be682ca | 762 | SSL_CTX_set_verify(sctx, |
059ec3d9 PH |
763 | SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT), |
764 | verify_callback); | |
765 | } | |
766 | ||
767 | return OK; | |
768 | } | |
769 | ||
770 | ||
771 | ||
772 | /************************************************* | |
773 | * Start a TLS session in a server * | |
774 | *************************************************/ | |
775 | ||
776 | /* This is called when Exim is running as a server, after having received | |
777 | the STARTTLS command. It must respond to that command, and then negotiate | |
778 | a TLS session. | |
779 | ||
780 | Arguments: | |
781 | require_ciphers allowed ciphers | |
83da1223 PH |
782 | ------------------------------------------------------ |
783 | require_mac list of allowed MACs ) Not used | |
784 | require_kx list of allowed key_exchange methods ) for | |
785 | require_proto list of allowed protocols ) OpenSSL | |
786 | ------------------------------------------------------ | |
059ec3d9 PH |
787 | |
788 | Returns: OK on success | |
789 | DEFER for errors before the start of the negotiation | |
790 | FAIL for errors during the negotation; the server can't | |
791 | continue running. | |
792 | */ | |
793 | ||
794 | int | |
83da1223 PH |
795 | tls_server_start(uschar *require_ciphers, uschar *require_mac, |
796 | uschar *require_kx, uschar *require_proto) | |
059ec3d9 PH |
797 | { |
798 | int rc; | |
799 | uschar *expciphers; | |
7be682ca | 800 | tls_ext_ctx_cb *cbinfo; |
059ec3d9 PH |
801 | |
802 | /* Check for previous activation */ | |
803 | ||
804 | if (tls_active >= 0) | |
805 | { | |
5ca6d115 | 806 | tls_error(US"STARTTLS received after TLS started", NULL, US""); |
059ec3d9 PH |
807 | smtp_printf("554 Already in TLS\r\n"); |
808 | return FAIL; | |
809 | } | |
810 | ||
811 | /* Initialize the SSL library. If it fails, it will already have logged | |
812 | the error. */ | |
813 | ||
814 | rc = tls_init(NULL, tls_dhparam, tls_certificate, tls_privatekey, NULL); | |
815 | if (rc != OK) return rc; | |
7be682ca | 816 | cbinfo = static_cbinfo; |
059ec3d9 PH |
817 | |
818 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers)) | |
819 | return FAIL; | |
820 | ||
821 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they | |
822 | are separated by underscores. So that I can use either form in my tests, and | |
823 | also for general convenience, we turn underscores into hyphens here. */ | |
824 | ||
825 | if (expciphers != NULL) | |
826 | { | |
827 | uschar *s = expciphers; | |
828 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } | |
829 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); | |
830 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) | |
7199e1ee | 831 | return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL); |
7be682ca | 832 | cbinfo->server_cipher_list = expciphers; |
059ec3d9 PH |
833 | } |
834 | ||
835 | /* If this is a host for which certificate verification is mandatory or | |
836 | optional, set up appropriately. */ | |
837 | ||
838 | tls_certificate_verified = FALSE; | |
839 | verify_callback_called = FALSE; | |
840 | ||
841 | if (verify_check_host(&tls_verify_hosts) == OK) | |
842 | { | |
7be682ca | 843 | rc = setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, FALSE); |
059ec3d9 PH |
844 | if (rc != OK) return rc; |
845 | verify_optional = FALSE; | |
846 | } | |
847 | else if (verify_check_host(&tls_try_verify_hosts) == OK) | |
848 | { | |
7be682ca | 849 | rc = setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, TRUE); |
059ec3d9 PH |
850 | if (rc != OK) return rc; |
851 | verify_optional = TRUE; | |
852 | } | |
853 | ||
854 | /* Prepare for new connection */ | |
855 | ||
7199e1ee | 856 | if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL); |
da3ad30d PP |
857 | |
858 | /* Warning: we used to SSL_clear(ssl) here, it was removed. | |
859 | * | |
860 | * With the SSL_clear(), we get strange interoperability bugs with | |
861 | * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in | |
862 | * OpenSSL itself, as a clear should not lead to inability to follow protocols. | |
863 | * | |
864 | * The SSL_clear() call is to let an existing SSL* be reused, typically after | |
865 | * session shutdown. In this case, we have a brand new object and there's no | |
866 | * obvious reason to immediately clear it. I'm guessing that this was | |
867 | * originally added because of incomplete initialisation which the clear fixed, | |
868 | * in some historic release. | |
869 | */ | |
059ec3d9 PH |
870 | |
871 | /* Set context and tell client to go ahead, except in the case of TLS startup | |
872 | on connection, where outputting anything now upsets the clients and tends to | |
873 | make them disconnect. We need to have an explicit fflush() here, to force out | |
874 | the response. Other smtp_printf() calls do not need it, because in non-TLS | |
875 | mode, the fflush() happens when smtp_getc() is called. */ | |
876 | ||
877 | SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx)); | |
878 | if (!tls_on_connect) | |
879 | { | |
880 | smtp_printf("220 TLS go ahead\r\n"); | |
881 | fflush(smtp_out); | |
882 | } | |
883 | ||
884 | /* Now negotiate the TLS session. We put our own timer on it, since it seems | |
885 | that the OpenSSL library doesn't. */ | |
886 | ||
56f5d9bd PH |
887 | SSL_set_wfd(ssl, fileno(smtp_out)); |
888 | SSL_set_rfd(ssl, fileno(smtp_in)); | |
059ec3d9 PH |
889 | SSL_set_accept_state(ssl); |
890 | ||
891 | DEBUG(D_tls) debug_printf("Calling SSL_accept\n"); | |
892 | ||
893 | sigalrm_seen = FALSE; | |
894 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
895 | rc = SSL_accept(ssl); | |
896 | alarm(0); | |
897 | ||
898 | if (rc <= 0) | |
899 | { | |
7199e1ee | 900 | tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL); |
77bb000f PP |
901 | if (ERR_get_error() == 0) |
902 | log_write(0, LOG_MAIN, | |
a053d125 | 903 | "TLS client disconnected cleanly (rejected our certificate?)"); |
059ec3d9 PH |
904 | return FAIL; |
905 | } | |
906 | ||
907 | DEBUG(D_tls) debug_printf("SSL_accept was successful\n"); | |
908 | ||
909 | /* TLS has been set up. Adjust the input functions to read via TLS, | |
910 | and initialize things. */ | |
911 | ||
912 | construct_cipher_name(ssl); | |
913 | ||
914 | DEBUG(D_tls) | |
915 | { | |
916 | uschar buf[2048]; | |
917 | if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)) != NULL) | |
918 | debug_printf("Shared ciphers: %s\n", buf); | |
919 | } | |
920 | ||
921 | ||
922 | ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size); | |
923 | ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0; | |
924 | ssl_xfer_eof = ssl_xfer_error = 0; | |
925 | ||
926 | receive_getc = tls_getc; | |
927 | receive_ungetc = tls_ungetc; | |
928 | receive_feof = tls_feof; | |
929 | receive_ferror = tls_ferror; | |
58eb016e | 930 | receive_smtp_buffered = tls_smtp_buffered; |
059ec3d9 PH |
931 | |
932 | tls_active = fileno(smtp_out); | |
933 | return OK; | |
934 | } | |
935 | ||
936 | ||
937 | ||
938 | ||
939 | ||
940 | /************************************************* | |
941 | * Start a TLS session in a client * | |
942 | *************************************************/ | |
943 | ||
944 | /* Called from the smtp transport after STARTTLS has been accepted. | |
945 | ||
946 | Argument: | |
947 | fd the fd of the connection | |
948 | host connected host (for messages) | |
83da1223 | 949 | addr the first address |
059ec3d9 PH |
950 | dhparam DH parameter file |
951 | certificate certificate file | |
952 | privatekey private key file | |
3f0945ff | 953 | sni TLS SNI to send to remote host |
059ec3d9 PH |
954 | verify_certs file for certificate verify |
955 | crl file containing CRL | |
956 | require_ciphers list of allowed ciphers | |
83da1223 PH |
957 | ------------------------------------------------------ |
958 | require_mac list of allowed MACs ) Not used | |
959 | require_kx list of allowed key_exchange methods ) for | |
960 | require_proto list of allowed protocols ) OpenSSL | |
961 | ------------------------------------------------------ | |
962 | timeout startup timeout | |
059ec3d9 PH |
963 | |
964 | Returns: OK on success | |
965 | FAIL otherwise - note that tls_error() will not give DEFER | |
966 | because this is not a server | |
967 | */ | |
968 | ||
969 | int | |
970 | tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam, | |
3f0945ff PP |
971 | uschar *certificate, uschar *privatekey, uschar *sni, |
972 | uschar *verify_certs, uschar *crl, | |
83da1223 PH |
973 | uschar *require_ciphers, uschar *require_mac, uschar *require_kx, |
974 | uschar *require_proto, int timeout) | |
059ec3d9 PH |
975 | { |
976 | static uschar txt[256]; | |
977 | uschar *expciphers; | |
978 | X509* server_cert; | |
979 | int rc; | |
980 | ||
981 | rc = tls_init(host, dhparam, certificate, privatekey, addr); | |
982 | if (rc != OK) return rc; | |
983 | ||
984 | tls_certificate_verified = FALSE; | |
985 | verify_callback_called = FALSE; | |
986 | ||
987 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers)) | |
988 | return FAIL; | |
989 | ||
990 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they | |
991 | are separated by underscores. So that I can use either form in my tests, and | |
992 | also for general convenience, we turn underscores into hyphens here. */ | |
993 | ||
994 | if (expciphers != NULL) | |
995 | { | |
996 | uschar *s = expciphers; | |
997 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } | |
998 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); | |
999 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) | |
7199e1ee | 1000 | return tls_error(US"SSL_CTX_set_cipher_list", host, NULL); |
059ec3d9 PH |
1001 | } |
1002 | ||
7be682ca | 1003 | rc = setup_certs(ctx, verify_certs, crl, host, FALSE); |
059ec3d9 PH |
1004 | if (rc != OK) return rc; |
1005 | ||
7199e1ee | 1006 | if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", host, NULL); |
059ec3d9 PH |
1007 | SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx)); |
1008 | SSL_set_fd(ssl, fd); | |
1009 | SSL_set_connect_state(ssl); | |
1010 | ||
3f0945ff PP |
1011 | if (sni) |
1012 | { | |
1013 | if (!expand_check(sni, US"tls_sni", &tls_sni)) | |
1014 | return FAIL; | |
1015 | if (!Ustrlen(tls_sni)) | |
1016 | tls_sni = NULL; | |
1017 | else | |
1018 | { | |
1019 | DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_sni); | |
1020 | SSL_set_tlsext_host_name(ssl, tls_sni); | |
1021 | } | |
1022 | } | |
1023 | ||
059ec3d9 PH |
1024 | /* There doesn't seem to be a built-in timeout on connection. */ |
1025 | ||
1026 | DEBUG(D_tls) debug_printf("Calling SSL_connect\n"); | |
1027 | sigalrm_seen = FALSE; | |
1028 | alarm(timeout); | |
1029 | rc = SSL_connect(ssl); | |
1030 | alarm(0); | |
1031 | ||
1032 | if (rc <= 0) | |
7199e1ee | 1033 | return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL); |
059ec3d9 PH |
1034 | |
1035 | DEBUG(D_tls) debug_printf("SSL_connect succeeded\n"); | |
1036 | ||
453a6645 | 1037 | /* Beware anonymous ciphers which lead to server_cert being NULL */ |
059ec3d9 | 1038 | server_cert = SSL_get_peer_certificate (ssl); |
453a6645 PP |
1039 | if (server_cert) |
1040 | { | |
1041 | tls_peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert), | |
1042 | CS txt, sizeof(txt)); | |
1043 | tls_peerdn = txt; | |
1044 | } | |
1045 | else | |
1046 | tls_peerdn = NULL; | |
059ec3d9 PH |
1047 | |
1048 | construct_cipher_name(ssl); /* Sets tls_cipher */ | |
1049 | ||
1050 | tls_active = fd; | |
1051 | return OK; | |
1052 | } | |
1053 | ||
1054 | ||
1055 | ||
1056 | ||
1057 | ||
1058 | /************************************************* | |
1059 | * TLS version of getc * | |
1060 | *************************************************/ | |
1061 | ||
1062 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, | |
1063 | it refills the buffer via the SSL reading function. | |
1064 | ||
1065 | Arguments: none | |
1066 | Returns: the next character or EOF | |
1067 | */ | |
1068 | ||
1069 | int | |
1070 | tls_getc(void) | |
1071 | { | |
1072 | if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm) | |
1073 | { | |
1074 | int error; | |
1075 | int inbytes; | |
1076 | ||
c80c5570 PP |
1077 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl, |
1078 | ssl_xfer_buffer, ssl_xfer_buffer_size); | |
059ec3d9 PH |
1079 | |
1080 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
1081 | inbytes = SSL_read(ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size); | |
1082 | error = SSL_get_error(ssl, inbytes); | |
1083 | alarm(0); | |
1084 | ||
1085 | /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been | |
1086 | closed down, not that the socket itself has been closed down. Revert to | |
1087 | non-SSL handling. */ | |
1088 | ||
1089 | if (error == SSL_ERROR_ZERO_RETURN) | |
1090 | { | |
1091 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); | |
1092 | ||
1093 | receive_getc = smtp_getc; | |
1094 | receive_ungetc = smtp_ungetc; | |
1095 | receive_feof = smtp_feof; | |
1096 | receive_ferror = smtp_ferror; | |
58eb016e | 1097 | receive_smtp_buffered = smtp_buffered; |
059ec3d9 PH |
1098 | |
1099 | SSL_free(ssl); | |
1100 | ssl = NULL; | |
1101 | tls_active = -1; | |
3f0945ff | 1102 | tls_bits = 0; |
059ec3d9 PH |
1103 | tls_cipher = NULL; |
1104 | tls_peerdn = NULL; | |
3f0945ff | 1105 | tls_sni = NULL; |
059ec3d9 PH |
1106 | |
1107 | return smtp_getc(); | |
1108 | } | |
1109 | ||
1110 | /* Handle genuine errors */ | |
1111 | ||
ba084640 PP |
1112 | else if (error == SSL_ERROR_SSL) |
1113 | { | |
1114 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
89dd51cd | 1115 | log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring); |
ba084640 PP |
1116 | ssl_xfer_error = 1; |
1117 | return EOF; | |
1118 | } | |
1119 | ||
059ec3d9 PH |
1120 | else if (error != SSL_ERROR_NONE) |
1121 | { | |
1122 | DEBUG(D_tls) debug_printf("Got SSL error %d\n", error); | |
1123 | ssl_xfer_error = 1; | |
1124 | return EOF; | |
1125 | } | |
c80c5570 | 1126 | |
80a47a2c TK |
1127 | #ifndef DISABLE_DKIM |
1128 | dkim_exim_verify_feed(ssl_xfer_buffer, inbytes); | |
1129 | #endif | |
059ec3d9 PH |
1130 | ssl_xfer_buffer_hwm = inbytes; |
1131 | ssl_xfer_buffer_lwm = 0; | |
1132 | } | |
1133 | ||
1134 | /* Something in the buffer; return next uschar */ | |
1135 | ||
1136 | return ssl_xfer_buffer[ssl_xfer_buffer_lwm++]; | |
1137 | } | |
1138 | ||
1139 | ||
1140 | ||
1141 | /************************************************* | |
1142 | * Read bytes from TLS channel * | |
1143 | *************************************************/ | |
1144 | ||
1145 | /* | |
1146 | Arguments: | |
1147 | buff buffer of data | |
1148 | len size of buffer | |
1149 | ||
1150 | Returns: the number of bytes read | |
1151 | -1 after a failed read | |
1152 | */ | |
1153 | ||
1154 | int | |
1155 | tls_read(uschar *buff, size_t len) | |
1156 | { | |
1157 | int inbytes; | |
1158 | int error; | |
1159 | ||
c80c5570 PP |
1160 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl, |
1161 | buff, (unsigned int)len); | |
059ec3d9 PH |
1162 | |
1163 | inbytes = SSL_read(ssl, CS buff, len); | |
1164 | error = SSL_get_error(ssl, inbytes); | |
1165 | ||
1166 | if (error == SSL_ERROR_ZERO_RETURN) | |
1167 | { | |
1168 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); | |
1169 | return -1; | |
1170 | } | |
1171 | else if (error != SSL_ERROR_NONE) | |
1172 | { | |
1173 | return -1; | |
1174 | } | |
1175 | ||
1176 | return inbytes; | |
1177 | } | |
1178 | ||
1179 | ||
1180 | ||
1181 | ||
1182 | ||
1183 | /************************************************* | |
1184 | * Write bytes down TLS channel * | |
1185 | *************************************************/ | |
1186 | ||
1187 | /* | |
1188 | Arguments: | |
1189 | buff buffer of data | |
1190 | len number of bytes | |
1191 | ||
1192 | Returns: the number of bytes after a successful write, | |
1193 | -1 after a failed write | |
1194 | */ | |
1195 | ||
1196 | int | |
1197 | tls_write(const uschar *buff, size_t len) | |
1198 | { | |
1199 | int outbytes; | |
1200 | int error; | |
1201 | int left = len; | |
1202 | ||
c80c5570 | 1203 | DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left); |
059ec3d9 PH |
1204 | while (left > 0) |
1205 | { | |
c80c5570 | 1206 | DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left); |
059ec3d9 PH |
1207 | outbytes = SSL_write(ssl, CS buff, left); |
1208 | error = SSL_get_error(ssl, outbytes); | |
1209 | DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error); | |
1210 | switch (error) | |
1211 | { | |
1212 | case SSL_ERROR_SSL: | |
1213 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
1214 | log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring); | |
1215 | return -1; | |
1216 | ||
1217 | case SSL_ERROR_NONE: | |
1218 | left -= outbytes; | |
1219 | buff += outbytes; | |
1220 | break; | |
1221 | ||
1222 | case SSL_ERROR_ZERO_RETURN: | |
1223 | log_write(0, LOG_MAIN, "SSL channel closed on write"); | |
1224 | return -1; | |
1225 | ||
1226 | default: | |
1227 | log_write(0, LOG_MAIN, "SSL_write error %d", error); | |
1228 | return -1; | |
1229 | } | |
1230 | } | |
1231 | return len; | |
1232 | } | |
1233 | ||
1234 | ||
1235 | ||
1236 | /************************************************* | |
1237 | * Close down a TLS session * | |
1238 | *************************************************/ | |
1239 | ||
1240 | /* This is also called from within a delivery subprocess forked from the | |
1241 | daemon, to shut down the TLS library, without actually doing a shutdown (which | |
1242 | would tamper with the SSL session in the parent process). | |
1243 | ||
1244 | Arguments: TRUE if SSL_shutdown is to be called | |
1245 | Returns: nothing | |
1246 | */ | |
1247 | ||
1248 | void | |
1249 | tls_close(BOOL shutdown) | |
1250 | { | |
1251 | if (tls_active < 0) return; /* TLS was not active */ | |
1252 | ||
1253 | if (shutdown) | |
1254 | { | |
1255 | DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n"); | |
1256 | SSL_shutdown(ssl); | |
1257 | } | |
1258 | ||
1259 | SSL_free(ssl); | |
1260 | ssl = NULL; | |
1261 | ||
1262 | tls_active = -1; | |
1263 | } | |
1264 | ||
36f12725 NM |
1265 | |
1266 | ||
1267 | ||
1268 | /************************************************* | |
1269 | * Report the library versions. * | |
1270 | *************************************************/ | |
1271 | ||
1272 | /* There have historically been some issues with binary compatibility in | |
1273 | OpenSSL libraries; if Exim (like many other applications) is built against | |
1274 | one version of OpenSSL but the run-time linker picks up another version, | |
1275 | it can result in serious failures, including crashing with a SIGSEGV. So | |
1276 | report the version found by the compiler and the run-time version. | |
1277 | ||
1278 | Arguments: a FILE* to print the results to | |
1279 | Returns: nothing | |
1280 | */ | |
1281 | ||
1282 | void | |
1283 | tls_version_report(FILE *f) | |
1284 | { | |
754a0503 PP |
1285 | fprintf(f, "Library version: OpenSSL: Compile: %s\n" |
1286 | " Runtime: %s\n", | |
1287 | OPENSSL_VERSION_TEXT, | |
1288 | SSLeay_version(SSLEAY_VERSION)); | |
36f12725 NM |
1289 | } |
1290 | ||
9e3331ea TK |
1291 | |
1292 | ||
1293 | ||
1294 | /************************************************* | |
1295 | * Pseudo-random number generation * | |
1296 | *************************************************/ | |
1297 | ||
1298 | /* Pseudo-random number generation. The result is not expected to be | |
1299 | cryptographically strong but not so weak that someone will shoot themselves | |
1300 | in the foot using it as a nonce in input in some email header scheme or | |
1301 | whatever weirdness they'll twist this into. The result should handle fork() | |
1302 | and avoid repeating sequences. OpenSSL handles that for us. | |
1303 | ||
1304 | Arguments: | |
1305 | max range maximum | |
1306 | Returns a random number in range [0, max-1] | |
1307 | */ | |
1308 | ||
1309 | int | |
1310 | pseudo_random_number(int max) | |
1311 | { | |
1312 | unsigned int r; | |
1313 | int i, needed_len; | |
1314 | uschar *p; | |
1315 | uschar smallbuf[sizeof(r)]; | |
1316 | ||
1317 | if (max <= 1) | |
1318 | return 0; | |
1319 | ||
1320 | /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */ | |
1321 | if (!RAND_status()) | |
1322 | { | |
1323 | randstuff r; | |
1324 | gettimeofday(&r.tv, NULL); | |
1325 | r.p = getpid(); | |
1326 | ||
1327 | RAND_seed((uschar *)(&r), sizeof(r)); | |
1328 | } | |
1329 | /* We're after pseudo-random, not random; if we still don't have enough data | |
1330 | in the internal PRNG then our options are limited. We could sleep and hope | |
1331 | for entropy to come along (prayer technique) but if the system is so depleted | |
1332 | in the first place then something is likely to just keep taking it. Instead, | |
1333 | we'll just take whatever little bit of pseudo-random we can still manage to | |
1334 | get. */ | |
1335 | ||
1336 | needed_len = sizeof(r); | |
1337 | /* Don't take 8 times more entropy than needed if int is 8 octets and we were | |
1338 | asked for a number less than 10. */ | |
1339 | for (r = max, i = 0; r; ++i) | |
1340 | r >>= 1; | |
1341 | i = (i + 7) / 8; | |
1342 | if (i < needed_len) | |
1343 | needed_len = i; | |
1344 | ||
1345 | /* We do not care if crypto-strong */ | |
1346 | (void) RAND_pseudo_bytes(smallbuf, needed_len); | |
1347 | r = 0; | |
1348 | for (p = smallbuf; needed_len; --needed_len, ++p) | |
1349 | { | |
1350 | r *= 256; | |
1351 | r += *p; | |
1352 | } | |
1353 | ||
1354 | /* We don't particularly care about weighted results; if someone wants | |
1355 | smooth distribution and cares enough then they should submit a patch then. */ | |
1356 | return r % max; | |
1357 | } | |
1358 | ||
77bb000f PP |
1359 | |
1360 | ||
1361 | ||
1362 | /************************************************* | |
1363 | * OpenSSL option parse * | |
1364 | *************************************************/ | |
1365 | ||
1366 | /* Parse one option for tls_openssl_options_parse below | |
1367 | ||
1368 | Arguments: | |
1369 | name one option name | |
1370 | value place to store a value for it | |
1371 | Returns success or failure in parsing | |
1372 | */ | |
1373 | ||
1374 | struct exim_openssl_option { | |
1375 | uschar *name; | |
1376 | long value; | |
1377 | }; | |
1378 | /* We could use a macro to expand, but we need the ifdef and not all the | |
1379 | options document which version they were introduced in. Policylet: include | |
1380 | all options unless explicitly for DTLS, let the administrator choose which | |
1381 | to apply. | |
1382 | ||
1383 | This list is current as of: | |
c80c5570 | 1384 | ==> 1.0.1b <== */ |
77bb000f PP |
1385 | static struct exim_openssl_option exim_openssl_options[] = { |
1386 | /* KEEP SORTED ALPHABETICALLY! */ | |
1387 | #ifdef SSL_OP_ALL | |
73a46702 | 1388 | { US"all", SSL_OP_ALL }, |
77bb000f PP |
1389 | #endif |
1390 | #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION | |
73a46702 | 1391 | { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION }, |
77bb000f PP |
1392 | #endif |
1393 | #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE | |
73a46702 | 1394 | { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE }, |
77bb000f PP |
1395 | #endif |
1396 | #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS | |
73a46702 | 1397 | { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS }, |
77bb000f PP |
1398 | #endif |
1399 | #ifdef SSL_OP_EPHEMERAL_RSA | |
73a46702 | 1400 | { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA }, |
77bb000f PP |
1401 | #endif |
1402 | #ifdef SSL_OP_LEGACY_SERVER_CONNECT | |
73a46702 | 1403 | { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT }, |
77bb000f PP |
1404 | #endif |
1405 | #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER | |
73a46702 | 1406 | { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER }, |
77bb000f PP |
1407 | #endif |
1408 | #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG | |
73a46702 | 1409 | { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG }, |
77bb000f PP |
1410 | #endif |
1411 | #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING | |
73a46702 | 1412 | { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING }, |
77bb000f PP |
1413 | #endif |
1414 | #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG | |
73a46702 | 1415 | { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG }, |
77bb000f PP |
1416 | #endif |
1417 | #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG | |
73a46702 | 1418 | { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG }, |
77bb000f | 1419 | #endif |
c80c5570 PP |
1420 | #ifdef SSL_OP_NO_COMPRESSION |
1421 | { US"no_compression", SSL_OP_NO_COMPRESSION }, | |
1422 | #endif | |
77bb000f | 1423 | #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION |
73a46702 | 1424 | { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION }, |
77bb000f | 1425 | #endif |
c0c7b2da PP |
1426 | #ifdef SSL_OP_NO_SSLv2 |
1427 | { US"no_sslv2", SSL_OP_NO_SSLv2 }, | |
1428 | #endif | |
1429 | #ifdef SSL_OP_NO_SSLv3 | |
1430 | { US"no_sslv3", SSL_OP_NO_SSLv3 }, | |
1431 | #endif | |
1432 | #ifdef SSL_OP_NO_TICKET | |
1433 | { US"no_ticket", SSL_OP_NO_TICKET }, | |
1434 | #endif | |
1435 | #ifdef SSL_OP_NO_TLSv1 | |
1436 | { US"no_tlsv1", SSL_OP_NO_TLSv1 }, | |
1437 | #endif | |
c80c5570 PP |
1438 | #ifdef SSL_OP_NO_TLSv1_1 |
1439 | #if SSL_OP_NO_TLSv1_1 == 0x00000400L | |
1440 | /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */ | |
1441 | #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring | |
1442 | #else | |
1443 | { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 }, | |
1444 | #endif | |
1445 | #endif | |
1446 | #ifdef SSL_OP_NO_TLSv1_2 | |
1447 | { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 }, | |
1448 | #endif | |
77bb000f | 1449 | #ifdef SSL_OP_SINGLE_DH_USE |
73a46702 | 1450 | { US"single_dh_use", SSL_OP_SINGLE_DH_USE }, |
77bb000f PP |
1451 | #endif |
1452 | #ifdef SSL_OP_SINGLE_ECDH_USE | |
73a46702 | 1453 | { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE }, |
77bb000f PP |
1454 | #endif |
1455 | #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG | |
73a46702 | 1456 | { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG }, |
77bb000f PP |
1457 | #endif |
1458 | #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG | |
73a46702 | 1459 | { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG }, |
77bb000f PP |
1460 | #endif |
1461 | #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG | |
73a46702 | 1462 | { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG }, |
77bb000f PP |
1463 | #endif |
1464 | #ifdef SSL_OP_TLS_D5_BUG | |
73a46702 | 1465 | { US"tls_d5_bug", SSL_OP_TLS_D5_BUG }, |
77bb000f PP |
1466 | #endif |
1467 | #ifdef SSL_OP_TLS_ROLLBACK_BUG | |
73a46702 | 1468 | { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG }, |
77bb000f PP |
1469 | #endif |
1470 | }; | |
1471 | static int exim_openssl_options_size = | |
1472 | sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option); | |
1473 | ||
c80c5570 | 1474 | |
77bb000f PP |
1475 | static BOOL |
1476 | tls_openssl_one_option_parse(uschar *name, long *value) | |
1477 | { | |
1478 | int first = 0; | |
1479 | int last = exim_openssl_options_size; | |
1480 | while (last > first) | |
1481 | { | |
1482 | int middle = (first + last)/2; | |
1483 | int c = Ustrcmp(name, exim_openssl_options[middle].name); | |
1484 | if (c == 0) | |
1485 | { | |
1486 | *value = exim_openssl_options[middle].value; | |
1487 | return TRUE; | |
1488 | } | |
1489 | else if (c > 0) | |
1490 | first = middle + 1; | |
1491 | else | |
1492 | last = middle; | |
1493 | } | |
1494 | return FALSE; | |
1495 | } | |
1496 | ||
1497 | ||
1498 | ||
1499 | ||
1500 | /************************************************* | |
1501 | * OpenSSL option parsing logic * | |
1502 | *************************************************/ | |
1503 | ||
1504 | /* OpenSSL has a number of compatibility options which an administrator might | |
1505 | reasonably wish to set. Interpret a list similarly to decode_bits(), so that | |
1506 | we look like log_selector. | |
1507 | ||
1508 | Arguments: | |
1509 | option_spec the administrator-supplied string of options | |
1510 | results ptr to long storage for the options bitmap | |
1511 | Returns success or failure | |
1512 | */ | |
1513 | ||
1514 | BOOL | |
1515 | tls_openssl_options_parse(uschar *option_spec, long *results) | |
1516 | { | |
1517 | long result, item; | |
1518 | uschar *s, *end; | |
1519 | uschar keep_c; | |
1520 | BOOL adding, item_parsed; | |
1521 | ||
0e944a0d | 1522 | result = 0L; |
da3ad30d PP |
1523 | /* Prior to 4.78 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed |
1524 | * from default because it increases BEAST susceptibility. */ | |
77bb000f PP |
1525 | |
1526 | if (option_spec == NULL) | |
1527 | { | |
1528 | *results = result; | |
1529 | return TRUE; | |
1530 | } | |
1531 | ||
1532 | for (s=option_spec; *s != '\0'; /**/) | |
1533 | { | |
1534 | while (isspace(*s)) ++s; | |
1535 | if (*s == '\0') | |
1536 | break; | |
1537 | if (*s != '+' && *s != '-') | |
1538 | { | |
1539 | DEBUG(D_tls) debug_printf("malformed openssl option setting: " | |
0e944a0d | 1540 | "+ or - expected but found \"%s\"\n", s); |
77bb000f PP |
1541 | return FALSE; |
1542 | } | |
1543 | adding = *s++ == '+'; | |
1544 | for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ; | |
1545 | keep_c = *end; | |
1546 | *end = '\0'; | |
1547 | item_parsed = tls_openssl_one_option_parse(s, &item); | |
1548 | if (!item_parsed) | |
1549 | { | |
0e944a0d | 1550 | DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s); |
77bb000f PP |
1551 | return FALSE; |
1552 | } | |
1553 | DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n", | |
1554 | adding ? "adding" : "removing", result, item, s); | |
1555 | if (adding) | |
1556 | result |= item; | |
1557 | else | |
1558 | result &= ~item; | |
1559 | *end = keep_c; | |
1560 | s = end; | |
1561 | } | |
1562 | ||
1563 | *results = result; | |
1564 | return TRUE; | |
1565 | } | |
1566 | ||
059ec3d9 | 1567 | /* End of tls-openssl.c */ |