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; | |
37 | static SSL *ssl = NULL; | |
38 | ||
39 | static char ssl_errstring[256]; | |
40 | ||
41 | static int ssl_session_timeout = 200; | |
42 | static BOOL verify_optional = FALSE; | |
43 | ||
44 | ||
45 | ||
46 | ||
47 | ||
48 | /************************************************* | |
49 | * Handle TLS error * | |
50 | *************************************************/ | |
51 | ||
52 | /* Called from lots of places when errors occur before actually starting to do | |
53 | the TLS handshake, that is, while the session is still in clear. Always returns | |
54 | DEFER for a server and FAIL for a client so that most calls can use "return | |
55 | tls_error(...)" to do this processing and then give an appropriate return. A | |
56 | single function is used for both server and client, because it is called from | |
57 | some shared functions. | |
58 | ||
59 | Argument: | |
60 | prefix text to include in the logged error | |
61 | host NULL if setting up a server; | |
62 | the connected host if setting up a client | |
7199e1ee | 63 | msg error message or NULL if we should ask OpenSSL |
059ec3d9 PH |
64 | |
65 | Returns: OK/DEFER/FAIL | |
66 | */ | |
67 | ||
68 | static int | |
7199e1ee | 69 | tls_error(uschar *prefix, host_item *host, uschar *msg) |
059ec3d9 | 70 | { |
7199e1ee TF |
71 | if (msg == NULL) |
72 | { | |
73 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
5ca6d115 | 74 | msg = (uschar *)ssl_errstring; |
7199e1ee TF |
75 | } |
76 | ||
059ec3d9 PH |
77 | if (host == NULL) |
78 | { | |
7199e1ee | 79 | uschar *conn_info = smtp_get_connection_info(); |
5ca6d115 | 80 | if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) |
7199e1ee TF |
81 | conn_info += 5; |
82 | log_write(0, LOG_MAIN, "TLS error on %s (%s): %s", | |
83 | conn_info, prefix, msg); | |
059ec3d9 PH |
84 | return DEFER; |
85 | } | |
86 | else | |
87 | { | |
88 | log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s): %s", | |
7199e1ee | 89 | host->name, host->address, prefix, msg); |
059ec3d9 PH |
90 | return FAIL; |
91 | } | |
92 | } | |
93 | ||
94 | ||
95 | ||
96 | /************************************************* | |
97 | * Callback to generate RSA key * | |
98 | *************************************************/ | |
99 | ||
100 | /* | |
101 | Arguments: | |
102 | s SSL connection | |
103 | export not used | |
104 | keylength keylength | |
105 | ||
106 | Returns: pointer to generated key | |
107 | */ | |
108 | ||
109 | static RSA * | |
110 | rsa_callback(SSL *s, int export, int keylength) | |
111 | { | |
112 | RSA *rsa_key; | |
113 | export = export; /* Shut picky compilers up */ | |
114 | DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength); | |
115 | rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL); | |
116 | if (rsa_key == NULL) | |
117 | { | |
118 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
119 | log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s", | |
120 | ssl_errstring); | |
121 | return NULL; | |
122 | } | |
123 | return rsa_key; | |
124 | } | |
125 | ||
126 | ||
127 | ||
128 | ||
129 | /************************************************* | |
130 | * Callback for verification * | |
131 | *************************************************/ | |
132 | ||
133 | /* The SSL library does certificate verification if set up to do so. This | |
134 | callback has the current yes/no state is in "state". If verification succeeded, | |
135 | we set up the tls_peerdn string. If verification failed, what happens depends | |
136 | on whether the client is required to present a verifiable certificate or not. | |
137 | ||
138 | If verification is optional, we change the state to yes, but still log the | |
139 | verification error. For some reason (it really would help to have proper | |
140 | documentation of OpenSSL), this callback function then gets called again, this | |
141 | time with state = 1. In fact, that's useful, because we can set up the peerdn | |
142 | value, but we must take care not to set the private verified flag on the second | |
143 | time through. | |
144 | ||
145 | Note: this function is not called if the client fails to present a certificate | |
146 | when asked. We get here only if a certificate has been received. Handling of | |
147 | optional verification for this case is done when requesting SSL to verify, by | |
148 | setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case. | |
149 | ||
150 | Arguments: | |
151 | state current yes/no state as 1/0 | |
152 | x509ctx certificate information. | |
153 | ||
154 | Returns: 1 if verified, 0 if not | |
155 | */ | |
156 | ||
157 | static int | |
158 | verify_callback(int state, X509_STORE_CTX *x509ctx) | |
159 | { | |
160 | static uschar txt[256]; | |
161 | ||
162 | X509_NAME_oneline(X509_get_subject_name(x509ctx->current_cert), | |
163 | CS txt, sizeof(txt)); | |
164 | ||
165 | if (state == 0) | |
166 | { | |
167 | log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s", | |
168 | x509ctx->error_depth, | |
169 | X509_verify_cert_error_string(x509ctx->error), | |
170 | txt); | |
171 | tls_certificate_verified = FALSE; | |
172 | verify_callback_called = TRUE; | |
173 | if (!verify_optional) return 0; /* reject */ | |
174 | DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in " | |
175 | "tls_try_verify_hosts)\n"); | |
176 | return 1; /* accept */ | |
177 | } | |
178 | ||
179 | if (x509ctx->error_depth != 0) | |
180 | { | |
181 | DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d cert=%s\n", | |
182 | x509ctx->error_depth, txt); | |
183 | } | |
184 | else | |
185 | { | |
186 | DEBUG(D_tls) debug_printf("SSL%s peer: %s\n", | |
187 | verify_callback_called? "" : " authenticated", txt); | |
188 | tls_peerdn = txt; | |
189 | } | |
190 | ||
059ec3d9 PH |
191 | if (!verify_callback_called) tls_certificate_verified = TRUE; |
192 | verify_callback_called = TRUE; | |
193 | ||
194 | return 1; /* accept */ | |
195 | } | |
196 | ||
197 | ||
198 | ||
199 | /************************************************* | |
200 | * Information callback * | |
201 | *************************************************/ | |
202 | ||
203 | /* The SSL library functions call this from time to time to indicate what they | |
204 | are doing. We copy the string to the debugging output when the level is high | |
205 | enough. | |
206 | ||
207 | Arguments: | |
208 | s the SSL connection | |
209 | where | |
210 | ret | |
211 | ||
212 | Returns: nothing | |
213 | */ | |
214 | ||
215 | static void | |
216 | info_callback(SSL *s, int where, int ret) | |
217 | { | |
218 | where = where; | |
219 | ret = ret; | |
220 | DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s)); | |
221 | } | |
222 | ||
223 | ||
224 | ||
225 | /************************************************* | |
226 | * Initialize for DH * | |
227 | *************************************************/ | |
228 | ||
229 | /* If dhparam is set, expand it, and load up the parameters for DH encryption. | |
230 | ||
231 | Arguments: | |
232 | dhparam DH parameter file | |
7199e1ee | 233 | host connected host, if client; NULL if server |
059ec3d9 PH |
234 | |
235 | Returns: TRUE if OK (nothing to set up, or setup worked) | |
236 | */ | |
237 | ||
238 | static BOOL | |
7199e1ee | 239 | init_dh(uschar *dhparam, host_item *host) |
059ec3d9 PH |
240 | { |
241 | BOOL yield = TRUE; | |
242 | BIO *bio; | |
243 | DH *dh; | |
244 | uschar *dhexpanded; | |
245 | ||
246 | if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded)) | |
247 | return FALSE; | |
248 | ||
249 | if (dhexpanded == NULL) return TRUE; | |
250 | ||
251 | if ((bio = BIO_new_file(CS dhexpanded, "r")) == NULL) | |
252 | { | |
7199e1ee | 253 | tls_error(string_sprintf("could not read dhparams file %s", dhexpanded), |
5ca6d115 | 254 | host, (uschar *)strerror(errno)); |
059ec3d9 PH |
255 | yield = FALSE; |
256 | } | |
257 | else | |
258 | { | |
259 | if ((dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)) == NULL) | |
260 | { | |
7199e1ee TF |
261 | tls_error(string_sprintf("could not read dhparams file %s", dhexpanded), |
262 | host, NULL); | |
059ec3d9 PH |
263 | yield = FALSE; |
264 | } | |
265 | else | |
266 | { | |
267 | SSL_CTX_set_tmp_dh(ctx, dh); | |
268 | DEBUG(D_tls) | |
269 | debug_printf("Diffie-Hellman initialized from %s with %d-bit key\n", | |
270 | dhexpanded, 8*DH_size(dh)); | |
271 | DH_free(dh); | |
272 | } | |
273 | BIO_free(bio); | |
274 | } | |
275 | ||
276 | return yield; | |
277 | } | |
278 | ||
279 | ||
280 | ||
281 | ||
282 | /************************************************* | |
283 | * Initialize for TLS * | |
284 | *************************************************/ | |
285 | ||
286 | /* Called from both server and client code, to do preliminary initialization of | |
287 | the library. | |
288 | ||
289 | Arguments: | |
290 | host connected host, if client; NULL if server | |
291 | dhparam DH parameter file | |
292 | certificate certificate file | |
293 | privatekey private key | |
294 | addr address if client; NULL if server (for some randomness) | |
295 | ||
296 | Returns: OK/DEFER/FAIL | |
297 | */ | |
298 | ||
299 | static int | |
c91535f3 PH |
300 | tls_init(host_item *host, uschar *dhparam, uschar *certificate, |
301 | uschar *privatekey, address_item *addr) | |
059ec3d9 | 302 | { |
77bb000f PP |
303 | long init_options; |
304 | BOOL okay; | |
305 | ||
059ec3d9 PH |
306 | SSL_load_error_strings(); /* basic set up */ |
307 | OpenSSL_add_ssl_algorithms(); | |
308 | ||
388d6564 | 309 | #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256) |
77bb000f | 310 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the |
a0475b69 TK |
311 | list of available digests. */ |
312 | EVP_add_digest(EVP_sha256()); | |
cf1ef1a9 | 313 | #endif |
a0475b69 | 314 | |
059ec3d9 PH |
315 | /* Create a context */ |
316 | ||
317 | ctx = SSL_CTX_new((host == NULL)? | |
318 | SSLv23_server_method() : SSLv23_client_method()); | |
319 | ||
7199e1ee | 320 | if (ctx == NULL) return tls_error(US"SSL_CTX_new", host, NULL); |
059ec3d9 PH |
321 | |
322 | /* It turns out that we need to seed the random number generator this early in | |
323 | order to get the full complement of ciphers to work. It took me roughly a day | |
324 | of work to discover this by experiment. | |
325 | ||
326 | On systems that have /dev/urandom, SSL may automatically seed itself from | |
327 | there. Otherwise, we have to make something up as best we can. Double check | |
328 | afterwards. */ | |
329 | ||
330 | if (!RAND_status()) | |
331 | { | |
332 | randstuff r; | |
9e3331ea | 333 | gettimeofday(&r.tv, NULL); |
059ec3d9 PH |
334 | r.p = getpid(); |
335 | ||
336 | RAND_seed((uschar *)(&r), sizeof(r)); | |
337 | RAND_seed((uschar *)big_buffer, big_buffer_size); | |
338 | if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr)); | |
339 | ||
340 | if (!RAND_status()) | |
7199e1ee | 341 | return tls_error(US"RAND_status", host, |
5ca6d115 | 342 | US"unable to seed random number generator"); |
059ec3d9 PH |
343 | } |
344 | ||
345 | /* Set up the information callback, which outputs if debugging is at a suitable | |
346 | level. */ | |
347 | ||
58c01c94 | 348 | SSL_CTX_set_info_callback(ctx, (void (*)())info_callback); |
059ec3d9 | 349 | |
c80c5570 PP |
350 | /* Automatically re-try reads/writes after renegotiation. */ |
351 | (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY); | |
352 | ||
77bb000f PP |
353 | /* Apply administrator-supplied work-arounds. |
354 | Historically we applied just one requested option, | |
355 | SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we | |
356 | moved to an administrator-controlled list of options to specify and | |
357 | grandfathered in the first one as the default value for "openssl_options". | |
059ec3d9 | 358 | |
77bb000f PP |
359 | No OpenSSL version number checks: the options we accept depend upon the |
360 | availability of the option value macros from OpenSSL. */ | |
059ec3d9 | 361 | |
77bb000f PP |
362 | okay = tls_openssl_options_parse(openssl_options, &init_options); |
363 | if (!okay) | |
73a46702 | 364 | return tls_error(US"openssl_options parsing failed", host, NULL); |
77bb000f PP |
365 | |
366 | if (init_options) | |
367 | { | |
368 | DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options); | |
369 | if (!(SSL_CTX_set_options(ctx, init_options))) | |
370 | return tls_error(string_sprintf( | |
371 | "SSL_CTX_set_option(%#lx)", init_options), host, NULL); | |
372 | } | |
373 | else | |
374 | DEBUG(D_tls) debug_printf("no SSL CTX options to set\n"); | |
059ec3d9 PH |
375 | |
376 | /* Initialize with DH parameters if supplied */ | |
377 | ||
7199e1ee | 378 | if (!init_dh(dhparam, host)) return DEFER; |
059ec3d9 PH |
379 | |
380 | /* Set up certificate and key */ | |
381 | ||
382 | if (certificate != NULL) | |
383 | { | |
384 | uschar *expanded; | |
385 | if (!expand_check(certificate, US"tls_certificate", &expanded)) | |
386 | return DEFER; | |
387 | ||
388 | if (expanded != NULL) | |
389 | { | |
390 | DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded); | |
391 | if (!SSL_CTX_use_certificate_chain_file(ctx, CS expanded)) | |
d6453af2 | 392 | return tls_error(string_sprintf( |
7199e1ee | 393 | "SSL_CTX_use_certificate_chain_file file=%s", expanded), host, NULL); |
059ec3d9 PH |
394 | } |
395 | ||
396 | if (privatekey != NULL && | |
397 | !expand_check(privatekey, US"tls_privatekey", &expanded)) | |
398 | return DEFER; | |
399 | ||
c91535f3 PH |
400 | /* If expansion was forced to fail, key_expanded will be NULL. If the result |
401 | of the expansion is an empty string, ignore it also, and assume the private | |
402 | key is in the same file as the certificate. */ | |
403 | ||
404 | if (expanded != NULL && *expanded != 0) | |
059ec3d9 PH |
405 | { |
406 | DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded); | |
407 | if (!SSL_CTX_use_PrivateKey_file(ctx, CS expanded, SSL_FILETYPE_PEM)) | |
d6453af2 | 408 | return tls_error(string_sprintf( |
7199e1ee | 409 | "SSL_CTX_use_PrivateKey_file file=%s", expanded), host, NULL); |
059ec3d9 PH |
410 | } |
411 | } | |
412 | ||
413 | /* Set up the RSA callback */ | |
414 | ||
415 | SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback); | |
416 | ||
417 | /* Finally, set the timeout, and we are done */ | |
418 | ||
419 | SSL_CTX_set_timeout(ctx, ssl_session_timeout); | |
420 | DEBUG(D_tls) debug_printf("Initialized TLS\n"); | |
421 | return OK; | |
422 | } | |
423 | ||
424 | ||
425 | ||
426 | ||
427 | /************************************************* | |
428 | * Get name of cipher in use * | |
429 | *************************************************/ | |
430 | ||
431 | /* The answer is left in a static buffer, and tls_cipher is set to point | |
432 | to it. | |
433 | ||
434 | Argument: pointer to an SSL structure for the connection | |
435 | Returns: nothing | |
436 | */ | |
437 | ||
438 | static void | |
439 | construct_cipher_name(SSL *ssl) | |
440 | { | |
441 | static uschar cipherbuf[256]; | |
57b3a7f5 PP |
442 | /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't |
443 | yet reflect that. It should be a safe change anyway, even 0.9.8 versions have | |
444 | the accessor functions use const in the prototype. */ | |
445 | const SSL_CIPHER *c; | |
059ec3d9 | 446 | uschar *ver; |
059ec3d9 PH |
447 | |
448 | switch (ssl->session->ssl_version) | |
449 | { | |
450 | case SSL2_VERSION: | |
451 | ver = US"SSLv2"; | |
452 | break; | |
453 | ||
454 | case SSL3_VERSION: | |
455 | ver = US"SSLv3"; | |
456 | break; | |
457 | ||
458 | case TLS1_VERSION: | |
459 | ver = US"TLSv1"; | |
460 | break; | |
461 | ||
c80c5570 PP |
462 | #ifdef TLS1_1_VERSION |
463 | case TLS1_1_VERSION: | |
464 | ver = US"TLSv1.1"; | |
465 | break; | |
466 | #endif | |
467 | ||
468 | #ifdef TLS1_2_VERSION | |
469 | case TLS1_2_VERSION: | |
470 | ver = US"TLSv1.2"; | |
471 | break; | |
472 | #endif | |
473 | ||
059ec3d9 PH |
474 | default: |
475 | ver = US"UNKNOWN"; | |
476 | } | |
477 | ||
57b3a7f5 | 478 | c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl); |
edc33b5f | 479 | SSL_CIPHER_get_bits(c, &tls_bits); |
059ec3d9 PH |
480 | |
481 | string_format(cipherbuf, sizeof(cipherbuf), "%s:%s:%u", ver, | |
edc33b5f | 482 | SSL_CIPHER_get_name(c), tls_bits); |
059ec3d9 PH |
483 | tls_cipher = cipherbuf; |
484 | ||
485 | DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf); | |
486 | } | |
487 | ||
488 | ||
489 | ||
490 | ||
491 | ||
492 | /************************************************* | |
493 | * Set up for verifying certificates * | |
494 | *************************************************/ | |
495 | ||
496 | /* Called by both client and server startup | |
497 | ||
498 | Arguments: | |
499 | certs certs file or NULL | |
500 | crl CRL file or NULL | |
501 | host NULL in a server; the remote host in a client | |
502 | optional TRUE if called from a server for a host in tls_try_verify_hosts; | |
503 | otherwise passed as FALSE | |
504 | ||
505 | Returns: OK/DEFER/FAIL | |
506 | */ | |
507 | ||
508 | static int | |
509 | setup_certs(uschar *certs, uschar *crl, host_item *host, BOOL optional) | |
510 | { | |
511 | uschar *expcerts, *expcrl; | |
512 | ||
513 | if (!expand_check(certs, US"tls_verify_certificates", &expcerts)) | |
514 | return DEFER; | |
515 | ||
516 | if (expcerts != NULL) | |
517 | { | |
518 | struct stat statbuf; | |
519 | if (!SSL_CTX_set_default_verify_paths(ctx)) | |
7199e1ee | 520 | return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL); |
059ec3d9 PH |
521 | |
522 | if (Ustat(expcerts, &statbuf) < 0) | |
523 | { | |
524 | log_write(0, LOG_MAIN|LOG_PANIC, | |
525 | "failed to stat %s for certificates", expcerts); | |
526 | return DEFER; | |
527 | } | |
528 | else | |
529 | { | |
530 | uschar *file, *dir; | |
531 | if ((statbuf.st_mode & S_IFMT) == S_IFDIR) | |
532 | { file = NULL; dir = expcerts; } | |
533 | else | |
534 | { file = expcerts; dir = NULL; } | |
535 | ||
536 | /* If a certificate file is empty, the next function fails with an | |
537 | unhelpful error message. If we skip it, we get the correct behaviour (no | |
538 | certificates are recognized, but the error message is still misleading (it | |
539 | says no certificate was supplied.) But this is better. */ | |
540 | ||
541 | if ((file == NULL || statbuf.st_size > 0) && | |
542 | !SSL_CTX_load_verify_locations(ctx, CS file, CS dir)) | |
7199e1ee | 543 | return tls_error(US"SSL_CTX_load_verify_locations", host, NULL); |
059ec3d9 PH |
544 | |
545 | if (file != NULL) | |
546 | { | |
547 | SSL_CTX_set_client_CA_list(ctx, SSL_load_client_CA_file(CS file)); | |
548 | } | |
549 | } | |
550 | ||
551 | /* Handle a certificate revocation list. */ | |
552 | ||
553 | #if OPENSSL_VERSION_NUMBER > 0x00907000L | |
554 | ||
8b417f2c PH |
555 | /* This bit of code is now the version supplied by Lars Mainka. (I have |
556 | * merely reformatted it into the Exim code style.) | |
557 | ||
558 | * "From here I changed the code to add support for multiple crl's | |
559 | * in pem format in one file or to support hashed directory entries in | |
560 | * pem format instead of a file. This method now uses the library function | |
561 | * X509_STORE_load_locations to add the CRL location to the SSL context. | |
562 | * OpenSSL will then handle the verify against CA certs and CRLs by | |
563 | * itself in the verify callback." */ | |
564 | ||
059ec3d9 PH |
565 | if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER; |
566 | if (expcrl != NULL && *expcrl != 0) | |
567 | { | |
8b417f2c PH |
568 | struct stat statbufcrl; |
569 | if (Ustat(expcrl, &statbufcrl) < 0) | |
570 | { | |
571 | log_write(0, LOG_MAIN|LOG_PANIC, | |
572 | "failed to stat %s for certificates revocation lists", expcrl); | |
573 | return DEFER; | |
574 | } | |
575 | else | |
059ec3d9 | 576 | { |
8b417f2c PH |
577 | /* is it a file or directory? */ |
578 | uschar *file, *dir; | |
579 | X509_STORE *cvstore = SSL_CTX_get_cert_store(ctx); | |
580 | if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR) | |
059ec3d9 | 581 | { |
8b417f2c PH |
582 | file = NULL; |
583 | dir = expcrl; | |
584 | DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir); | |
059ec3d9 PH |
585 | } |
586 | else | |
587 | { | |
8b417f2c PH |
588 | file = expcrl; |
589 | dir = NULL; | |
590 | DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file); | |
059ec3d9 | 591 | } |
8b417f2c | 592 | if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0) |
7199e1ee | 593 | return tls_error(US"X509_STORE_load_locations", host, NULL); |
8b417f2c PH |
594 | |
595 | /* setting the flags to check against the complete crl chain */ | |
596 | ||
597 | X509_STORE_set_flags(cvstore, | |
598 | X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL); | |
059ec3d9 | 599 | } |
059ec3d9 PH |
600 | } |
601 | ||
602 | #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */ | |
603 | ||
604 | /* If verification is optional, don't fail if no certificate */ | |
605 | ||
606 | SSL_CTX_set_verify(ctx, | |
607 | SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT), | |
608 | verify_callback); | |
609 | } | |
610 | ||
611 | return OK; | |
612 | } | |
613 | ||
614 | ||
615 | ||
616 | /************************************************* | |
617 | * Start a TLS session in a server * | |
618 | *************************************************/ | |
619 | ||
620 | /* This is called when Exim is running as a server, after having received | |
621 | the STARTTLS command. It must respond to that command, and then negotiate | |
622 | a TLS session. | |
623 | ||
624 | Arguments: | |
625 | require_ciphers allowed ciphers | |
83da1223 PH |
626 | ------------------------------------------------------ |
627 | require_mac list of allowed MACs ) Not used | |
628 | require_kx list of allowed key_exchange methods ) for | |
629 | require_proto list of allowed protocols ) OpenSSL | |
630 | ------------------------------------------------------ | |
059ec3d9 PH |
631 | |
632 | Returns: OK on success | |
633 | DEFER for errors before the start of the negotiation | |
634 | FAIL for errors during the negotation; the server can't | |
635 | continue running. | |
636 | */ | |
637 | ||
638 | int | |
83da1223 PH |
639 | tls_server_start(uschar *require_ciphers, uschar *require_mac, |
640 | uschar *require_kx, uschar *require_proto) | |
059ec3d9 PH |
641 | { |
642 | int rc; | |
643 | uschar *expciphers; | |
644 | ||
645 | /* Check for previous activation */ | |
646 | ||
647 | if (tls_active >= 0) | |
648 | { | |
5ca6d115 | 649 | tls_error(US"STARTTLS received after TLS started", NULL, US""); |
059ec3d9 PH |
650 | smtp_printf("554 Already in TLS\r\n"); |
651 | return FAIL; | |
652 | } | |
653 | ||
654 | /* Initialize the SSL library. If it fails, it will already have logged | |
655 | the error. */ | |
656 | ||
657 | rc = tls_init(NULL, tls_dhparam, tls_certificate, tls_privatekey, NULL); | |
658 | if (rc != OK) return rc; | |
659 | ||
660 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers)) | |
661 | return FAIL; | |
662 | ||
663 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they | |
664 | are separated by underscores. So that I can use either form in my tests, and | |
665 | also for general convenience, we turn underscores into hyphens here. */ | |
666 | ||
667 | if (expciphers != NULL) | |
668 | { | |
669 | uschar *s = expciphers; | |
670 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } | |
671 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); | |
672 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) | |
7199e1ee | 673 | return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL); |
059ec3d9 PH |
674 | } |
675 | ||
676 | /* If this is a host for which certificate verification is mandatory or | |
677 | optional, set up appropriately. */ | |
678 | ||
679 | tls_certificate_verified = FALSE; | |
680 | verify_callback_called = FALSE; | |
681 | ||
682 | if (verify_check_host(&tls_verify_hosts) == OK) | |
683 | { | |
684 | rc = setup_certs(tls_verify_certificates, tls_crl, NULL, FALSE); | |
685 | if (rc != OK) return rc; | |
686 | verify_optional = FALSE; | |
687 | } | |
688 | else if (verify_check_host(&tls_try_verify_hosts) == OK) | |
689 | { | |
690 | rc = setup_certs(tls_verify_certificates, tls_crl, NULL, TRUE); | |
691 | if (rc != OK) return rc; | |
692 | verify_optional = TRUE; | |
693 | } | |
694 | ||
695 | /* Prepare for new connection */ | |
696 | ||
7199e1ee | 697 | if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL); |
059ec3d9 PH |
698 | SSL_clear(ssl); |
699 | ||
700 | /* Set context and tell client to go ahead, except in the case of TLS startup | |
701 | on connection, where outputting anything now upsets the clients and tends to | |
702 | make them disconnect. We need to have an explicit fflush() here, to force out | |
703 | the response. Other smtp_printf() calls do not need it, because in non-TLS | |
704 | mode, the fflush() happens when smtp_getc() is called. */ | |
705 | ||
706 | SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx)); | |
707 | if (!tls_on_connect) | |
708 | { | |
709 | smtp_printf("220 TLS go ahead\r\n"); | |
710 | fflush(smtp_out); | |
711 | } | |
712 | ||
713 | /* Now negotiate the TLS session. We put our own timer on it, since it seems | |
714 | that the OpenSSL library doesn't. */ | |
715 | ||
56f5d9bd PH |
716 | SSL_set_wfd(ssl, fileno(smtp_out)); |
717 | SSL_set_rfd(ssl, fileno(smtp_in)); | |
059ec3d9 PH |
718 | SSL_set_accept_state(ssl); |
719 | ||
720 | DEBUG(D_tls) debug_printf("Calling SSL_accept\n"); | |
721 | ||
722 | sigalrm_seen = FALSE; | |
723 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
724 | rc = SSL_accept(ssl); | |
725 | alarm(0); | |
726 | ||
727 | if (rc <= 0) | |
728 | { | |
7199e1ee | 729 | tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL); |
77bb000f PP |
730 | if (ERR_get_error() == 0) |
731 | log_write(0, LOG_MAIN, | |
a053d125 | 732 | "TLS client disconnected cleanly (rejected our certificate?)"); |
059ec3d9 PH |
733 | return FAIL; |
734 | } | |
735 | ||
736 | DEBUG(D_tls) debug_printf("SSL_accept was successful\n"); | |
737 | ||
738 | /* TLS has been set up. Adjust the input functions to read via TLS, | |
739 | and initialize things. */ | |
740 | ||
741 | construct_cipher_name(ssl); | |
742 | ||
743 | DEBUG(D_tls) | |
744 | { | |
745 | uschar buf[2048]; | |
746 | if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)) != NULL) | |
747 | debug_printf("Shared ciphers: %s\n", buf); | |
748 | } | |
749 | ||
750 | ||
751 | ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size); | |
752 | ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0; | |
753 | ssl_xfer_eof = ssl_xfer_error = 0; | |
754 | ||
755 | receive_getc = tls_getc; | |
756 | receive_ungetc = tls_ungetc; | |
757 | receive_feof = tls_feof; | |
758 | receive_ferror = tls_ferror; | |
58eb016e | 759 | receive_smtp_buffered = tls_smtp_buffered; |
059ec3d9 PH |
760 | |
761 | tls_active = fileno(smtp_out); | |
762 | return OK; | |
763 | } | |
764 | ||
765 | ||
766 | ||
767 | ||
768 | ||
769 | /************************************************* | |
770 | * Start a TLS session in a client * | |
771 | *************************************************/ | |
772 | ||
773 | /* Called from the smtp transport after STARTTLS has been accepted. | |
774 | ||
775 | Argument: | |
776 | fd the fd of the connection | |
777 | host connected host (for messages) | |
83da1223 | 778 | addr the first address |
059ec3d9 PH |
779 | dhparam DH parameter file |
780 | certificate certificate file | |
781 | privatekey private key file | |
782 | verify_certs file for certificate verify | |
783 | crl file containing CRL | |
784 | require_ciphers list of allowed ciphers | |
83da1223 PH |
785 | ------------------------------------------------------ |
786 | require_mac list of allowed MACs ) Not used | |
787 | require_kx list of allowed key_exchange methods ) for | |
788 | require_proto list of allowed protocols ) OpenSSL | |
789 | ------------------------------------------------------ | |
790 | timeout startup timeout | |
059ec3d9 PH |
791 | |
792 | Returns: OK on success | |
793 | FAIL otherwise - note that tls_error() will not give DEFER | |
794 | because this is not a server | |
795 | */ | |
796 | ||
797 | int | |
798 | tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam, | |
799 | uschar *certificate, uschar *privatekey, uschar *verify_certs, uschar *crl, | |
83da1223 PH |
800 | uschar *require_ciphers, uschar *require_mac, uschar *require_kx, |
801 | uschar *require_proto, int timeout) | |
059ec3d9 PH |
802 | { |
803 | static uschar txt[256]; | |
804 | uschar *expciphers; | |
805 | X509* server_cert; | |
806 | int rc; | |
807 | ||
808 | rc = tls_init(host, dhparam, certificate, privatekey, addr); | |
809 | if (rc != OK) return rc; | |
810 | ||
811 | tls_certificate_verified = FALSE; | |
812 | verify_callback_called = FALSE; | |
813 | ||
814 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers)) | |
815 | return FAIL; | |
816 | ||
817 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they | |
818 | are separated by underscores. So that I can use either form in my tests, and | |
819 | also for general convenience, we turn underscores into hyphens here. */ | |
820 | ||
821 | if (expciphers != NULL) | |
822 | { | |
823 | uschar *s = expciphers; | |
824 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } | |
825 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); | |
826 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) | |
7199e1ee | 827 | return tls_error(US"SSL_CTX_set_cipher_list", host, NULL); |
059ec3d9 PH |
828 | } |
829 | ||
830 | rc = setup_certs(verify_certs, crl, host, FALSE); | |
831 | if (rc != OK) return rc; | |
832 | ||
7199e1ee | 833 | if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", host, NULL); |
059ec3d9 PH |
834 | SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx)); |
835 | SSL_set_fd(ssl, fd); | |
836 | SSL_set_connect_state(ssl); | |
837 | ||
838 | /* There doesn't seem to be a built-in timeout on connection. */ | |
839 | ||
840 | DEBUG(D_tls) debug_printf("Calling SSL_connect\n"); | |
841 | sigalrm_seen = FALSE; | |
842 | alarm(timeout); | |
843 | rc = SSL_connect(ssl); | |
844 | alarm(0); | |
845 | ||
846 | if (rc <= 0) | |
7199e1ee | 847 | return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL); |
059ec3d9 PH |
848 | |
849 | DEBUG(D_tls) debug_printf("SSL_connect succeeded\n"); | |
850 | ||
453a6645 | 851 | /* Beware anonymous ciphers which lead to server_cert being NULL */ |
059ec3d9 | 852 | server_cert = SSL_get_peer_certificate (ssl); |
453a6645 PP |
853 | if (server_cert) |
854 | { | |
855 | tls_peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert), | |
856 | CS txt, sizeof(txt)); | |
857 | tls_peerdn = txt; | |
858 | } | |
859 | else | |
860 | tls_peerdn = NULL; | |
059ec3d9 PH |
861 | |
862 | construct_cipher_name(ssl); /* Sets tls_cipher */ | |
863 | ||
864 | tls_active = fd; | |
865 | return OK; | |
866 | } | |
867 | ||
868 | ||
869 | ||
870 | ||
871 | ||
872 | /************************************************* | |
873 | * TLS version of getc * | |
874 | *************************************************/ | |
875 | ||
876 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, | |
877 | it refills the buffer via the SSL reading function. | |
878 | ||
879 | Arguments: none | |
880 | Returns: the next character or EOF | |
881 | */ | |
882 | ||
883 | int | |
884 | tls_getc(void) | |
885 | { | |
886 | if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm) | |
887 | { | |
888 | int error; | |
889 | int inbytes; | |
890 | ||
c80c5570 PP |
891 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl, |
892 | ssl_xfer_buffer, ssl_xfer_buffer_size); | |
059ec3d9 PH |
893 | |
894 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
895 | inbytes = SSL_read(ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size); | |
896 | error = SSL_get_error(ssl, inbytes); | |
897 | alarm(0); | |
898 | ||
899 | /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been | |
900 | closed down, not that the socket itself has been closed down. Revert to | |
901 | non-SSL handling. */ | |
902 | ||
903 | if (error == SSL_ERROR_ZERO_RETURN) | |
904 | { | |
905 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); | |
906 | ||
907 | receive_getc = smtp_getc; | |
908 | receive_ungetc = smtp_ungetc; | |
909 | receive_feof = smtp_feof; | |
910 | receive_ferror = smtp_ferror; | |
58eb016e | 911 | receive_smtp_buffered = smtp_buffered; |
059ec3d9 PH |
912 | |
913 | SSL_free(ssl); | |
914 | ssl = NULL; | |
915 | tls_active = -1; | |
916 | tls_cipher = NULL; | |
917 | tls_peerdn = NULL; | |
918 | ||
919 | return smtp_getc(); | |
920 | } | |
921 | ||
922 | /* Handle genuine errors */ | |
923 | ||
ba084640 PP |
924 | else if (error == SSL_ERROR_SSL) |
925 | { | |
926 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
89dd51cd | 927 | log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring); |
ba084640 PP |
928 | ssl_xfer_error = 1; |
929 | return EOF; | |
930 | } | |
931 | ||
059ec3d9 PH |
932 | else if (error != SSL_ERROR_NONE) |
933 | { | |
934 | DEBUG(D_tls) debug_printf("Got SSL error %d\n", error); | |
935 | ssl_xfer_error = 1; | |
936 | return EOF; | |
937 | } | |
c80c5570 | 938 | |
80a47a2c TK |
939 | #ifndef DISABLE_DKIM |
940 | dkim_exim_verify_feed(ssl_xfer_buffer, inbytes); | |
941 | #endif | |
059ec3d9 PH |
942 | ssl_xfer_buffer_hwm = inbytes; |
943 | ssl_xfer_buffer_lwm = 0; | |
944 | } | |
945 | ||
946 | /* Something in the buffer; return next uschar */ | |
947 | ||
948 | return ssl_xfer_buffer[ssl_xfer_buffer_lwm++]; | |
949 | } | |
950 | ||
951 | ||
952 | ||
953 | /************************************************* | |
954 | * Read bytes from TLS channel * | |
955 | *************************************************/ | |
956 | ||
957 | /* | |
958 | Arguments: | |
959 | buff buffer of data | |
960 | len size of buffer | |
961 | ||
962 | Returns: the number of bytes read | |
963 | -1 after a failed read | |
964 | */ | |
965 | ||
966 | int | |
967 | tls_read(uschar *buff, size_t len) | |
968 | { | |
969 | int inbytes; | |
970 | int error; | |
971 | ||
c80c5570 PP |
972 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl, |
973 | buff, (unsigned int)len); | |
059ec3d9 PH |
974 | |
975 | inbytes = SSL_read(ssl, CS buff, len); | |
976 | error = SSL_get_error(ssl, inbytes); | |
977 | ||
978 | if (error == SSL_ERROR_ZERO_RETURN) | |
979 | { | |
980 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); | |
981 | return -1; | |
982 | } | |
983 | else if (error != SSL_ERROR_NONE) | |
984 | { | |
985 | return -1; | |
986 | } | |
987 | ||
988 | return inbytes; | |
989 | } | |
990 | ||
991 | ||
992 | ||
993 | ||
994 | ||
995 | /************************************************* | |
996 | * Write bytes down TLS channel * | |
997 | *************************************************/ | |
998 | ||
999 | /* | |
1000 | Arguments: | |
1001 | buff buffer of data | |
1002 | len number of bytes | |
1003 | ||
1004 | Returns: the number of bytes after a successful write, | |
1005 | -1 after a failed write | |
1006 | */ | |
1007 | ||
1008 | int | |
1009 | tls_write(const uschar *buff, size_t len) | |
1010 | { | |
1011 | int outbytes; | |
1012 | int error; | |
1013 | int left = len; | |
1014 | ||
c80c5570 | 1015 | DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left); |
059ec3d9 PH |
1016 | while (left > 0) |
1017 | { | |
c80c5570 | 1018 | DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left); |
059ec3d9 PH |
1019 | outbytes = SSL_write(ssl, CS buff, left); |
1020 | error = SSL_get_error(ssl, outbytes); | |
1021 | DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error); | |
1022 | switch (error) | |
1023 | { | |
1024 | case SSL_ERROR_SSL: | |
1025 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
1026 | log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring); | |
1027 | return -1; | |
1028 | ||
1029 | case SSL_ERROR_NONE: | |
1030 | left -= outbytes; | |
1031 | buff += outbytes; | |
1032 | break; | |
1033 | ||
1034 | case SSL_ERROR_ZERO_RETURN: | |
1035 | log_write(0, LOG_MAIN, "SSL channel closed on write"); | |
1036 | return -1; | |
1037 | ||
1038 | default: | |
1039 | log_write(0, LOG_MAIN, "SSL_write error %d", error); | |
1040 | return -1; | |
1041 | } | |
1042 | } | |
1043 | return len; | |
1044 | } | |
1045 | ||
1046 | ||
1047 | ||
1048 | /************************************************* | |
1049 | * Close down a TLS session * | |
1050 | *************************************************/ | |
1051 | ||
1052 | /* This is also called from within a delivery subprocess forked from the | |
1053 | daemon, to shut down the TLS library, without actually doing a shutdown (which | |
1054 | would tamper with the SSL session in the parent process). | |
1055 | ||
1056 | Arguments: TRUE if SSL_shutdown is to be called | |
1057 | Returns: nothing | |
1058 | */ | |
1059 | ||
1060 | void | |
1061 | tls_close(BOOL shutdown) | |
1062 | { | |
1063 | if (tls_active < 0) return; /* TLS was not active */ | |
1064 | ||
1065 | if (shutdown) | |
1066 | { | |
1067 | DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n"); | |
1068 | SSL_shutdown(ssl); | |
1069 | } | |
1070 | ||
1071 | SSL_free(ssl); | |
1072 | ssl = NULL; | |
1073 | ||
1074 | tls_active = -1; | |
1075 | } | |
1076 | ||
36f12725 NM |
1077 | |
1078 | ||
1079 | ||
1080 | /************************************************* | |
1081 | * Report the library versions. * | |
1082 | *************************************************/ | |
1083 | ||
1084 | /* There have historically been some issues with binary compatibility in | |
1085 | OpenSSL libraries; if Exim (like many other applications) is built against | |
1086 | one version of OpenSSL but the run-time linker picks up another version, | |
1087 | it can result in serious failures, including crashing with a SIGSEGV. So | |
1088 | report the version found by the compiler and the run-time version. | |
1089 | ||
1090 | Arguments: a FILE* to print the results to | |
1091 | Returns: nothing | |
1092 | */ | |
1093 | ||
1094 | void | |
1095 | tls_version_report(FILE *f) | |
1096 | { | |
754a0503 PP |
1097 | fprintf(f, "Library version: OpenSSL: Compile: %s\n" |
1098 | " Runtime: %s\n", | |
1099 | OPENSSL_VERSION_TEXT, | |
1100 | SSLeay_version(SSLEAY_VERSION)); | |
36f12725 NM |
1101 | } |
1102 | ||
9e3331ea TK |
1103 | |
1104 | ||
1105 | ||
1106 | /************************************************* | |
1107 | * Pseudo-random number generation * | |
1108 | *************************************************/ | |
1109 | ||
1110 | /* Pseudo-random number generation. The result is not expected to be | |
1111 | cryptographically strong but not so weak that someone will shoot themselves | |
1112 | in the foot using it as a nonce in input in some email header scheme or | |
1113 | whatever weirdness they'll twist this into. The result should handle fork() | |
1114 | and avoid repeating sequences. OpenSSL handles that for us. | |
1115 | ||
1116 | Arguments: | |
1117 | max range maximum | |
1118 | Returns a random number in range [0, max-1] | |
1119 | */ | |
1120 | ||
1121 | int | |
1122 | pseudo_random_number(int max) | |
1123 | { | |
1124 | unsigned int r; | |
1125 | int i, needed_len; | |
1126 | uschar *p; | |
1127 | uschar smallbuf[sizeof(r)]; | |
1128 | ||
1129 | if (max <= 1) | |
1130 | return 0; | |
1131 | ||
1132 | /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */ | |
1133 | if (!RAND_status()) | |
1134 | { | |
1135 | randstuff r; | |
1136 | gettimeofday(&r.tv, NULL); | |
1137 | r.p = getpid(); | |
1138 | ||
1139 | RAND_seed((uschar *)(&r), sizeof(r)); | |
1140 | } | |
1141 | /* We're after pseudo-random, not random; if we still don't have enough data | |
1142 | in the internal PRNG then our options are limited. We could sleep and hope | |
1143 | for entropy to come along (prayer technique) but if the system is so depleted | |
1144 | in the first place then something is likely to just keep taking it. Instead, | |
1145 | we'll just take whatever little bit of pseudo-random we can still manage to | |
1146 | get. */ | |
1147 | ||
1148 | needed_len = sizeof(r); | |
1149 | /* Don't take 8 times more entropy than needed if int is 8 octets and we were | |
1150 | asked for a number less than 10. */ | |
1151 | for (r = max, i = 0; r; ++i) | |
1152 | r >>= 1; | |
1153 | i = (i + 7) / 8; | |
1154 | if (i < needed_len) | |
1155 | needed_len = i; | |
1156 | ||
1157 | /* We do not care if crypto-strong */ | |
1158 | (void) RAND_pseudo_bytes(smallbuf, needed_len); | |
1159 | r = 0; | |
1160 | for (p = smallbuf; needed_len; --needed_len, ++p) | |
1161 | { | |
1162 | r *= 256; | |
1163 | r += *p; | |
1164 | } | |
1165 | ||
1166 | /* We don't particularly care about weighted results; if someone wants | |
1167 | smooth distribution and cares enough then they should submit a patch then. */ | |
1168 | return r % max; | |
1169 | } | |
1170 | ||
77bb000f PP |
1171 | |
1172 | ||
1173 | ||
1174 | /************************************************* | |
1175 | * OpenSSL option parse * | |
1176 | *************************************************/ | |
1177 | ||
1178 | /* Parse one option for tls_openssl_options_parse below | |
1179 | ||
1180 | Arguments: | |
1181 | name one option name | |
1182 | value place to store a value for it | |
1183 | Returns success or failure in parsing | |
1184 | */ | |
1185 | ||
1186 | struct exim_openssl_option { | |
1187 | uschar *name; | |
1188 | long value; | |
1189 | }; | |
1190 | /* We could use a macro to expand, but we need the ifdef and not all the | |
1191 | options document which version they were introduced in. Policylet: include | |
1192 | all options unless explicitly for DTLS, let the administrator choose which | |
1193 | to apply. | |
1194 | ||
1195 | This list is current as of: | |
c80c5570 | 1196 | ==> 1.0.1b <== */ |
77bb000f PP |
1197 | static struct exim_openssl_option exim_openssl_options[] = { |
1198 | /* KEEP SORTED ALPHABETICALLY! */ | |
1199 | #ifdef SSL_OP_ALL | |
73a46702 | 1200 | { US"all", SSL_OP_ALL }, |
77bb000f PP |
1201 | #endif |
1202 | #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION | |
73a46702 | 1203 | { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION }, |
77bb000f PP |
1204 | #endif |
1205 | #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE | |
73a46702 | 1206 | { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE }, |
77bb000f PP |
1207 | #endif |
1208 | #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS | |
73a46702 | 1209 | { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS }, |
77bb000f PP |
1210 | #endif |
1211 | #ifdef SSL_OP_EPHEMERAL_RSA | |
73a46702 | 1212 | { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA }, |
77bb000f PP |
1213 | #endif |
1214 | #ifdef SSL_OP_LEGACY_SERVER_CONNECT | |
73a46702 | 1215 | { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT }, |
77bb000f PP |
1216 | #endif |
1217 | #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER | |
73a46702 | 1218 | { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER }, |
77bb000f PP |
1219 | #endif |
1220 | #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG | |
73a46702 | 1221 | { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG }, |
77bb000f PP |
1222 | #endif |
1223 | #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING | |
73a46702 | 1224 | { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING }, |
77bb000f PP |
1225 | #endif |
1226 | #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG | |
73a46702 | 1227 | { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG }, |
77bb000f PP |
1228 | #endif |
1229 | #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG | |
73a46702 | 1230 | { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG }, |
77bb000f | 1231 | #endif |
c80c5570 PP |
1232 | #ifdef SSL_OP_NO_COMPRESSION |
1233 | { US"no_compression", SSL_OP_NO_COMPRESSION }, | |
1234 | #endif | |
77bb000f | 1235 | #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION |
73a46702 | 1236 | { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION }, |
77bb000f | 1237 | #endif |
c0c7b2da PP |
1238 | #ifdef SSL_OP_NO_SSLv2 |
1239 | { US"no_sslv2", SSL_OP_NO_SSLv2 }, | |
1240 | #endif | |
1241 | #ifdef SSL_OP_NO_SSLv3 | |
1242 | { US"no_sslv3", SSL_OP_NO_SSLv3 }, | |
1243 | #endif | |
1244 | #ifdef SSL_OP_NO_TICKET | |
1245 | { US"no_ticket", SSL_OP_NO_TICKET }, | |
1246 | #endif | |
1247 | #ifdef SSL_OP_NO_TLSv1 | |
1248 | { US"no_tlsv1", SSL_OP_NO_TLSv1 }, | |
1249 | #endif | |
c80c5570 PP |
1250 | #ifdef SSL_OP_NO_TLSv1_1 |
1251 | #if SSL_OP_NO_TLSv1_1 == 0x00000400L | |
1252 | /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */ | |
1253 | #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring | |
1254 | #else | |
1255 | { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 }, | |
1256 | #endif | |
1257 | #endif | |
1258 | #ifdef SSL_OP_NO_TLSv1_2 | |
1259 | { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 }, | |
1260 | #endif | |
77bb000f | 1261 | #ifdef SSL_OP_SINGLE_DH_USE |
73a46702 | 1262 | { US"single_dh_use", SSL_OP_SINGLE_DH_USE }, |
77bb000f PP |
1263 | #endif |
1264 | #ifdef SSL_OP_SINGLE_ECDH_USE | |
73a46702 | 1265 | { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE }, |
77bb000f PP |
1266 | #endif |
1267 | #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG | |
73a46702 | 1268 | { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG }, |
77bb000f PP |
1269 | #endif |
1270 | #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG | |
73a46702 | 1271 | { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG }, |
77bb000f PP |
1272 | #endif |
1273 | #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG | |
73a46702 | 1274 | { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG }, |
77bb000f PP |
1275 | #endif |
1276 | #ifdef SSL_OP_TLS_D5_BUG | |
73a46702 | 1277 | { US"tls_d5_bug", SSL_OP_TLS_D5_BUG }, |
77bb000f PP |
1278 | #endif |
1279 | #ifdef SSL_OP_TLS_ROLLBACK_BUG | |
73a46702 | 1280 | { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG }, |
77bb000f PP |
1281 | #endif |
1282 | }; | |
1283 | static int exim_openssl_options_size = | |
1284 | sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option); | |
1285 | ||
c80c5570 | 1286 | |
77bb000f PP |
1287 | static BOOL |
1288 | tls_openssl_one_option_parse(uschar *name, long *value) | |
1289 | { | |
1290 | int first = 0; | |
1291 | int last = exim_openssl_options_size; | |
1292 | while (last > first) | |
1293 | { | |
1294 | int middle = (first + last)/2; | |
1295 | int c = Ustrcmp(name, exim_openssl_options[middle].name); | |
1296 | if (c == 0) | |
1297 | { | |
1298 | *value = exim_openssl_options[middle].value; | |
1299 | return TRUE; | |
1300 | } | |
1301 | else if (c > 0) | |
1302 | first = middle + 1; | |
1303 | else | |
1304 | last = middle; | |
1305 | } | |
1306 | return FALSE; | |
1307 | } | |
1308 | ||
1309 | ||
1310 | ||
1311 | ||
1312 | /************************************************* | |
1313 | * OpenSSL option parsing logic * | |
1314 | *************************************************/ | |
1315 | ||
1316 | /* OpenSSL has a number of compatibility options which an administrator might | |
1317 | reasonably wish to set. Interpret a list similarly to decode_bits(), so that | |
1318 | we look like log_selector. | |
1319 | ||
1320 | Arguments: | |
1321 | option_spec the administrator-supplied string of options | |
1322 | results ptr to long storage for the options bitmap | |
1323 | Returns success or failure | |
1324 | */ | |
1325 | ||
1326 | BOOL | |
1327 | tls_openssl_options_parse(uschar *option_spec, long *results) | |
1328 | { | |
1329 | long result, item; | |
1330 | uschar *s, *end; | |
1331 | uschar keep_c; | |
1332 | BOOL adding, item_parsed; | |
1333 | ||
0e944a0d | 1334 | result = 0L; |
77bb000f PP |
1335 | /* We grandfather in as default the one option which we used to set always. */ |
1336 | #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS | |
0e944a0d | 1337 | result |= SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; |
77bb000f PP |
1338 | #endif |
1339 | ||
1340 | if (option_spec == NULL) | |
1341 | { | |
1342 | *results = result; | |
1343 | return TRUE; | |
1344 | } | |
1345 | ||
1346 | for (s=option_spec; *s != '\0'; /**/) | |
1347 | { | |
1348 | while (isspace(*s)) ++s; | |
1349 | if (*s == '\0') | |
1350 | break; | |
1351 | if (*s != '+' && *s != '-') | |
1352 | { | |
1353 | DEBUG(D_tls) debug_printf("malformed openssl option setting: " | |
0e944a0d | 1354 | "+ or - expected but found \"%s\"\n", s); |
77bb000f PP |
1355 | return FALSE; |
1356 | } | |
1357 | adding = *s++ == '+'; | |
1358 | for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ; | |
1359 | keep_c = *end; | |
1360 | *end = '\0'; | |
1361 | item_parsed = tls_openssl_one_option_parse(s, &item); | |
1362 | if (!item_parsed) | |
1363 | { | |
0e944a0d | 1364 | DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s); |
77bb000f PP |
1365 | return FALSE; |
1366 | } | |
1367 | DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n", | |
1368 | adding ? "adding" : "removing", result, item, s); | |
1369 | if (adding) | |
1370 | result |= item; | |
1371 | else | |
1372 | result &= ~item; | |
1373 | *end = keep_c; | |
1374 | s = end; | |
1375 | } | |
1376 | ||
1377 | *results = result; | |
1378 | return TRUE; | |
1379 | } | |
1380 | ||
059ec3d9 | 1381 | /* End of tls-openssl.c */ |