Commit | Line | Data |
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059ec3d9 PH |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | ||
c4ceed07 | 5 | /* Copyright (c) University of Cambridge 1995 - 2012 */ |
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> | |
3f7eeb86 PP |
23 | #ifdef EXPERIMENTAL_OCSP |
24 | #include <openssl/ocsp.h> | |
25 | #endif | |
26 | ||
27 | #ifdef EXPERIMENTAL_OCSP | |
28 | #define EXIM_OCSP_SKEW_SECONDS (300L) | |
29 | #define EXIM_OCSP_MAX_AGE (-1L) | |
30 | #endif | |
059ec3d9 | 31 | |
3bcbbbe2 PP |
32 | #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT) |
33 | #define EXIM_HAVE_OPENSSL_TLSEXT | |
34 | #endif | |
35 | ||
059ec3d9 PH |
36 | /* Structure for collecting random data for seeding. */ |
37 | ||
38 | typedef struct randstuff { | |
9e3331ea TK |
39 | struct timeval tv; |
40 | pid_t p; | |
059ec3d9 PH |
41 | } randstuff; |
42 | ||
43 | /* Local static variables */ | |
44 | ||
45 | static BOOL verify_callback_called = FALSE; | |
46 | static const uschar *sid_ctx = US"exim"; | |
47 | ||
48 | static SSL_CTX *ctx = NULL; | |
7be682ca | 49 | static SSL_CTX *ctx_sni = NULL; |
059ec3d9 PH |
50 | static SSL *ssl = NULL; |
51 | ||
52 | static char ssl_errstring[256]; | |
53 | ||
54 | static int ssl_session_timeout = 200; | |
55 | static BOOL verify_optional = FALSE; | |
56 | ||
7be682ca | 57 | static BOOL reexpand_tls_files_for_sni = FALSE; |
059ec3d9 PH |
58 | |
59 | ||
7be682ca PP |
60 | typedef struct tls_ext_ctx_cb { |
61 | uschar *certificate; | |
62 | uschar *privatekey; | |
3f7eeb86 PP |
63 | #ifdef EXPERIMENTAL_OCSP |
64 | uschar *ocsp_file; | |
65 | uschar *ocsp_file_expanded; | |
66 | OCSP_RESPONSE *ocsp_response; | |
67 | #endif | |
7be682ca PP |
68 | uschar *dhparam; |
69 | /* these are cached from first expand */ | |
70 | uschar *server_cipher_list; | |
71 | /* only passed down to tls_error: */ | |
72 | host_item *host; | |
73 | } tls_ext_ctx_cb; | |
74 | ||
75 | /* should figure out a cleanup of API to handle state preserved per | |
76 | implementation, for various reasons, which can be void * in the APIs. | |
77 | For now, we hack around it. */ | |
78 | tls_ext_ctx_cb *static_cbinfo = NULL; | |
79 | ||
80 | static int | |
81 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional); | |
059ec3d9 | 82 | |
3f7eeb86 | 83 | /* Callbacks */ |
3bcbbbe2 | 84 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
3f7eeb86 | 85 | static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg); |
3bcbbbe2 | 86 | #endif |
3f7eeb86 PP |
87 | #ifdef EXPERIMENTAL_OCSP |
88 | static int tls_stapling_cb(SSL *s, void *arg); | |
89 | #endif | |
90 | ||
059ec3d9 PH |
91 | |
92 | /************************************************* | |
93 | * Handle TLS error * | |
94 | *************************************************/ | |
95 | ||
96 | /* Called from lots of places when errors occur before actually starting to do | |
97 | the TLS handshake, that is, while the session is still in clear. Always returns | |
98 | DEFER for a server and FAIL for a client so that most calls can use "return | |
99 | tls_error(...)" to do this processing and then give an appropriate return. A | |
100 | single function is used for both server and client, because it is called from | |
101 | some shared functions. | |
102 | ||
103 | Argument: | |
104 | prefix text to include in the logged error | |
105 | host NULL if setting up a server; | |
106 | the connected host if setting up a client | |
7199e1ee | 107 | msg error message or NULL if we should ask OpenSSL |
059ec3d9 PH |
108 | |
109 | Returns: OK/DEFER/FAIL | |
110 | */ | |
111 | ||
112 | static int | |
7199e1ee | 113 | tls_error(uschar *prefix, host_item *host, uschar *msg) |
059ec3d9 | 114 | { |
7199e1ee TF |
115 | if (msg == NULL) |
116 | { | |
117 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
5ca6d115 | 118 | msg = (uschar *)ssl_errstring; |
7199e1ee TF |
119 | } |
120 | ||
059ec3d9 PH |
121 | if (host == NULL) |
122 | { | |
7199e1ee | 123 | uschar *conn_info = smtp_get_connection_info(); |
5ca6d115 | 124 | if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) |
7199e1ee TF |
125 | conn_info += 5; |
126 | log_write(0, LOG_MAIN, "TLS error on %s (%s): %s", | |
127 | conn_info, prefix, msg); | |
059ec3d9 PH |
128 | return DEFER; |
129 | } | |
130 | else | |
131 | { | |
132 | log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s): %s", | |
7199e1ee | 133 | host->name, host->address, prefix, msg); |
059ec3d9 PH |
134 | return FAIL; |
135 | } | |
136 | } | |
137 | ||
138 | ||
139 | ||
140 | /************************************************* | |
141 | * Callback to generate RSA key * | |
142 | *************************************************/ | |
143 | ||
144 | /* | |
145 | Arguments: | |
146 | s SSL connection | |
147 | export not used | |
148 | keylength keylength | |
149 | ||
150 | Returns: pointer to generated key | |
151 | */ | |
152 | ||
153 | static RSA * | |
154 | rsa_callback(SSL *s, int export, int keylength) | |
155 | { | |
156 | RSA *rsa_key; | |
157 | export = export; /* Shut picky compilers up */ | |
158 | DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength); | |
159 | rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL); | |
160 | if (rsa_key == NULL) | |
161 | { | |
162 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
163 | log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s", | |
164 | ssl_errstring); | |
165 | return NULL; | |
166 | } | |
167 | return rsa_key; | |
168 | } | |
169 | ||
170 | ||
171 | ||
172 | ||
173 | /************************************************* | |
174 | * Callback for verification * | |
175 | *************************************************/ | |
176 | ||
177 | /* The SSL library does certificate verification if set up to do so. This | |
178 | callback has the current yes/no state is in "state". If verification succeeded, | |
179 | we set up the tls_peerdn string. If verification failed, what happens depends | |
180 | on whether the client is required to present a verifiable certificate or not. | |
181 | ||
182 | If verification is optional, we change the state to yes, but still log the | |
183 | verification error. For some reason (it really would help to have proper | |
184 | documentation of OpenSSL), this callback function then gets called again, this | |
185 | time with state = 1. In fact, that's useful, because we can set up the peerdn | |
186 | value, but we must take care not to set the private verified flag on the second | |
187 | time through. | |
188 | ||
189 | Note: this function is not called if the client fails to present a certificate | |
190 | when asked. We get here only if a certificate has been received. Handling of | |
191 | optional verification for this case is done when requesting SSL to verify, by | |
192 | setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case. | |
193 | ||
194 | Arguments: | |
195 | state current yes/no state as 1/0 | |
196 | x509ctx certificate information. | |
197 | ||
198 | Returns: 1 if verified, 0 if not | |
199 | */ | |
200 | ||
201 | static int | |
202 | verify_callback(int state, X509_STORE_CTX *x509ctx) | |
203 | { | |
204 | static uschar txt[256]; | |
205 | ||
206 | X509_NAME_oneline(X509_get_subject_name(x509ctx->current_cert), | |
207 | CS txt, sizeof(txt)); | |
208 | ||
209 | if (state == 0) | |
210 | { | |
211 | log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s", | |
212 | x509ctx->error_depth, | |
213 | X509_verify_cert_error_string(x509ctx->error), | |
214 | txt); | |
215 | tls_certificate_verified = FALSE; | |
216 | verify_callback_called = TRUE; | |
217 | if (!verify_optional) return 0; /* reject */ | |
218 | DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in " | |
219 | "tls_try_verify_hosts)\n"); | |
220 | return 1; /* accept */ | |
221 | } | |
222 | ||
223 | if (x509ctx->error_depth != 0) | |
224 | { | |
225 | DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d cert=%s\n", | |
226 | x509ctx->error_depth, txt); | |
227 | } | |
228 | else | |
229 | { | |
230 | DEBUG(D_tls) debug_printf("SSL%s peer: %s\n", | |
231 | verify_callback_called? "" : " authenticated", txt); | |
232 | tls_peerdn = txt; | |
233 | } | |
234 | ||
059ec3d9 PH |
235 | if (!verify_callback_called) tls_certificate_verified = TRUE; |
236 | verify_callback_called = TRUE; | |
237 | ||
238 | return 1; /* accept */ | |
239 | } | |
240 | ||
241 | ||
242 | ||
243 | /************************************************* | |
244 | * Information callback * | |
245 | *************************************************/ | |
246 | ||
247 | /* The SSL library functions call this from time to time to indicate what they | |
7be682ca PP |
248 | are doing. We copy the string to the debugging output when TLS debugging has |
249 | been requested. | |
059ec3d9 PH |
250 | |
251 | Arguments: | |
252 | s the SSL connection | |
253 | where | |
254 | ret | |
255 | ||
256 | Returns: nothing | |
257 | */ | |
258 | ||
259 | static void | |
260 | info_callback(SSL *s, int where, int ret) | |
261 | { | |
262 | where = where; | |
263 | ret = ret; | |
264 | DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s)); | |
265 | } | |
266 | ||
267 | ||
268 | ||
269 | /************************************************* | |
270 | * Initialize for DH * | |
271 | *************************************************/ | |
272 | ||
273 | /* If dhparam is set, expand it, and load up the parameters for DH encryption. | |
274 | ||
275 | Arguments: | |
276 | dhparam DH parameter file | |
7199e1ee | 277 | host connected host, if client; NULL if server |
059ec3d9 PH |
278 | |
279 | Returns: TRUE if OK (nothing to set up, or setup worked) | |
280 | */ | |
281 | ||
282 | static BOOL | |
7199e1ee | 283 | init_dh(uschar *dhparam, host_item *host) |
059ec3d9 PH |
284 | { |
285 | BOOL yield = TRUE; | |
286 | BIO *bio; | |
287 | DH *dh; | |
288 | uschar *dhexpanded; | |
289 | ||
290 | if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded)) | |
291 | return FALSE; | |
292 | ||
293 | if (dhexpanded == NULL) return TRUE; | |
294 | ||
295 | if ((bio = BIO_new_file(CS dhexpanded, "r")) == NULL) | |
296 | { | |
7199e1ee | 297 | tls_error(string_sprintf("could not read dhparams file %s", dhexpanded), |
5ca6d115 | 298 | host, (uschar *)strerror(errno)); |
059ec3d9 PH |
299 | yield = FALSE; |
300 | } | |
301 | else | |
302 | { | |
303 | if ((dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)) == NULL) | |
304 | { | |
7199e1ee TF |
305 | tls_error(string_sprintf("could not read dhparams file %s", dhexpanded), |
306 | host, NULL); | |
059ec3d9 PH |
307 | yield = FALSE; |
308 | } | |
309 | else | |
310 | { | |
3375e053 PP |
311 | if ((8*DH_size(dh)) > tls_dh_max_bits) |
312 | { | |
313 | DEBUG(D_tls) | |
314 | debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d", | |
315 | 8*DH_size(dh), tls_dh_max_bits); | |
316 | } | |
317 | else | |
318 | { | |
319 | SSL_CTX_set_tmp_dh(ctx, dh); | |
320 | DEBUG(D_tls) | |
321 | debug_printf("Diffie-Hellman initialized from %s with %d-bit key\n", | |
322 | dhexpanded, 8*DH_size(dh)); | |
323 | } | |
059ec3d9 PH |
324 | DH_free(dh); |
325 | } | |
326 | BIO_free(bio); | |
327 | } | |
328 | ||
329 | return yield; | |
330 | } | |
331 | ||
332 | ||
333 | ||
334 | ||
3f7eeb86 PP |
335 | #ifdef EXPERIMENTAL_OCSP |
336 | /************************************************* | |
337 | * Load OCSP information into state * | |
338 | *************************************************/ | |
339 | ||
340 | /* Called to load the OCSP response from the given file into memory, once | |
341 | caller has determined this is needed. Checks validity. Debugs a message | |
342 | if invalid. | |
343 | ||
344 | ASSUMES: single response, for single cert. | |
345 | ||
346 | Arguments: | |
347 | sctx the SSL_CTX* to update | |
348 | cbinfo various parts of session state | |
349 | expanded the filename putatively holding an OCSP response | |
350 | ||
351 | */ | |
352 | ||
353 | static void | |
354 | ocsp_load_response(SSL_CTX *sctx, | |
355 | tls_ext_ctx_cb *cbinfo, | |
356 | const uschar *expanded) | |
357 | { | |
358 | BIO *bio; | |
359 | OCSP_RESPONSE *resp; | |
360 | OCSP_BASICRESP *basic_response; | |
361 | OCSP_SINGLERESP *single_response; | |
362 | ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd; | |
363 | X509_STORE *store; | |
364 | unsigned long verify_flags; | |
365 | int status, reason, i; | |
366 | ||
367 | cbinfo->ocsp_file_expanded = string_copy(expanded); | |
368 | if (cbinfo->ocsp_response) | |
369 | { | |
370 | OCSP_RESPONSE_free(cbinfo->ocsp_response); | |
371 | cbinfo->ocsp_response = NULL; | |
372 | } | |
373 | ||
374 | bio = BIO_new_file(CS cbinfo->ocsp_file_expanded, "rb"); | |
375 | if (!bio) | |
376 | { | |
377 | DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n", | |
378 | cbinfo->ocsp_file_expanded); | |
379 | return; | |
380 | } | |
381 | ||
382 | resp = d2i_OCSP_RESPONSE_bio(bio, NULL); | |
383 | BIO_free(bio); | |
384 | if (!resp) | |
385 | { | |
386 | DEBUG(D_tls) debug_printf("Error reading OCSP response.\n"); | |
387 | return; | |
388 | } | |
389 | ||
390 | status = OCSP_response_status(resp); | |
391 | if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL) | |
392 | { | |
393 | DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n", | |
394 | OCSP_response_status_str(status), status); | |
395 | return; | |
396 | } | |
397 | ||
398 | basic_response = OCSP_response_get1_basic(resp); | |
399 | if (!basic_response) | |
400 | { | |
401 | DEBUG(D_tls) | |
402 | debug_printf("OCSP response parse error: unable to extract basic response.\n"); | |
403 | return; | |
404 | } | |
405 | ||
406 | store = SSL_CTX_get_cert_store(sctx); | |
407 | verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */ | |
408 | ||
409 | /* May need to expose ability to adjust those flags? | |
410 | OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT | |
411 | OCSP_TRUSTOTHER OCSP_NOINTERN */ | |
412 | ||
413 | i = OCSP_basic_verify(basic_response, NULL, store, verify_flags); | |
414 | if (i <= 0) | |
415 | { | |
416 | DEBUG(D_tls) { | |
417 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
418 | debug_printf("OCSP response verify failure: %s\n", US ssl_errstring); | |
419 | } | |
420 | return; | |
421 | } | |
422 | ||
423 | /* Here's the simplifying assumption: there's only one response, for the | |
424 | one certificate we use, and nothing for anything else in a chain. If this | |
425 | proves false, we need to extract a cert id from our issued cert | |
426 | (tls_certificate) and use that for OCSP_resp_find_status() (which finds the | |
427 | right cert in the stack and then calls OCSP_single_get0_status()). | |
428 | ||
429 | I'm hoping to avoid reworking a bunch more of how we handle state here. */ | |
430 | single_response = OCSP_resp_get0(basic_response, 0); | |
431 | if (!single_response) | |
432 | { | |
433 | DEBUG(D_tls) | |
434 | debug_printf("Unable to get first response from OCSP basic response.\n"); | |
435 | return; | |
436 | } | |
437 | ||
438 | status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd); | |
439 | /* how does this status differ from the one above? */ | |
440 | if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL) | |
441 | { | |
442 | DEBUG(D_tls) debug_printf("OCSP response not valid (take 2): %s (%d)\n", | |
443 | OCSP_response_status_str(status), status); | |
444 | return; | |
445 | } | |
446 | ||
447 | if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE)) | |
448 | { | |
449 | DEBUG(D_tls) debug_printf("OCSP status invalid times.\n"); | |
450 | return; | |
451 | } | |
452 | ||
453 | cbinfo->ocsp_response = resp; | |
454 | } | |
455 | #endif | |
456 | ||
457 | ||
458 | ||
459 | ||
7be682ca PP |
460 | /************************************************* |
461 | * Expand key and cert file specs * | |
462 | *************************************************/ | |
463 | ||
464 | /* Called once during tls_init and possibly againt during TLS setup, for a | |
465 | new context, if Server Name Indication was used and tls_sni was seen in | |
466 | the certificate string. | |
467 | ||
468 | Arguments: | |
469 | sctx the SSL_CTX* to update | |
470 | cbinfo various parts of session state | |
471 | ||
472 | Returns: OK/DEFER/FAIL | |
473 | */ | |
474 | ||
475 | static int | |
3f7eeb86 | 476 | tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo) |
7be682ca PP |
477 | { |
478 | uschar *expanded; | |
479 | ||
480 | if (cbinfo->certificate == NULL) | |
481 | return OK; | |
482 | ||
483 | if (Ustrstr(cbinfo->certificate, US"tls_sni")) | |
484 | reexpand_tls_files_for_sni = TRUE; | |
485 | ||
486 | if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded)) | |
487 | return DEFER; | |
488 | ||
489 | if (expanded != NULL) | |
490 | { | |
491 | DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded); | |
492 | if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded)) | |
493 | return tls_error(string_sprintf( | |
494 | "SSL_CTX_use_certificate_chain_file file=%s", expanded), | |
495 | cbinfo->host, NULL); | |
496 | } | |
497 | ||
498 | if (cbinfo->privatekey != NULL && | |
499 | !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded)) | |
500 | return DEFER; | |
501 | ||
502 | /* If expansion was forced to fail, key_expanded will be NULL. If the result | |
503 | of the expansion is an empty string, ignore it also, and assume the private | |
504 | key is in the same file as the certificate. */ | |
505 | ||
506 | if (expanded != NULL && *expanded != 0) | |
507 | { | |
508 | DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded); | |
509 | if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM)) | |
510 | return tls_error(string_sprintf( | |
511 | "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL); | |
512 | } | |
513 | ||
3f7eeb86 PP |
514 | #ifdef EXPERIMENTAL_OCSP |
515 | if (cbinfo->ocsp_file != NULL) | |
516 | { | |
517 | if (!expand_check(cbinfo->ocsp_file, US"tls_ocsp_file", &expanded)) | |
518 | return DEFER; | |
519 | ||
520 | if (expanded != NULL && *expanded != 0) | |
521 | { | |
522 | DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded); | |
523 | if (cbinfo->ocsp_file_expanded && | |
524 | (Ustrcmp(expanded, cbinfo->ocsp_file_expanded) == 0)) | |
525 | { | |
526 | DEBUG(D_tls) | |
527 | debug_printf("tls_ocsp_file value unchanged, using existing values.\n"); | |
528 | } else { | |
529 | ocsp_load_response(sctx, cbinfo, expanded); | |
530 | } | |
531 | } | |
532 | } | |
533 | #endif | |
534 | ||
7be682ca PP |
535 | return OK; |
536 | } | |
537 | ||
538 | ||
539 | ||
540 | ||
541 | /************************************************* | |
542 | * Callback to handle SNI * | |
543 | *************************************************/ | |
544 | ||
545 | /* Called when acting as server during the TLS session setup if a Server Name | |
546 | Indication extension was sent by the client. | |
547 | ||
548 | API documentation is OpenSSL s_server.c implementation. | |
549 | ||
550 | Arguments: | |
551 | s SSL* of the current session | |
552 | ad unknown (part of OpenSSL API) (unused) | |
553 | arg Callback of "our" registered data | |
554 | ||
555 | Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK} | |
556 | */ | |
557 | ||
3bcbbbe2 | 558 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
7be682ca PP |
559 | static int |
560 | tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg) | |
561 | { | |
562 | const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name); | |
3f7eeb86 | 563 | tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg; |
7be682ca | 564 | int rc; |
3f0945ff | 565 | int old_pool = store_pool; |
7be682ca PP |
566 | |
567 | if (!servername) | |
568 | return SSL_TLSEXT_ERR_OK; | |
569 | ||
3f0945ff | 570 | DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername, |
7be682ca PP |
571 | reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)"); |
572 | ||
573 | /* Make the extension value available for expansion */ | |
3f0945ff PP |
574 | store_pool = POOL_PERM; |
575 | tls_sni = string_copy(US servername); | |
576 | store_pool = old_pool; | |
7be682ca PP |
577 | |
578 | if (!reexpand_tls_files_for_sni) | |
579 | return SSL_TLSEXT_ERR_OK; | |
580 | ||
581 | /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually; | |
582 | not confident that memcpy wouldn't break some internal reference counting. | |
583 | Especially since there's a references struct member, which would be off. */ | |
584 | ||
585 | ctx_sni = SSL_CTX_new(SSLv23_server_method()); | |
586 | if (!ctx_sni) | |
587 | { | |
588 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
589 | DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring); | |
590 | return SSL_TLSEXT_ERR_NOACK; | |
591 | } | |
592 | ||
593 | /* Not sure how many of these are actually needed, since SSL object | |
594 | already exists. Might even need this selfsame callback, for reneg? */ | |
595 | ||
596 | SSL_CTX_set_info_callback(ctx_sni, SSL_CTX_get_info_callback(ctx)); | |
597 | SSL_CTX_set_mode(ctx_sni, SSL_CTX_get_mode(ctx)); | |
598 | SSL_CTX_set_options(ctx_sni, SSL_CTX_get_options(ctx)); | |
599 | SSL_CTX_set_timeout(ctx_sni, SSL_CTX_get_timeout(ctx)); | |
600 | SSL_CTX_set_tlsext_servername_callback(ctx_sni, tls_servername_cb); | |
601 | SSL_CTX_set_tlsext_servername_arg(ctx_sni, cbinfo); | |
602 | if (cbinfo->server_cipher_list) | |
603 | SSL_CTX_set_cipher_list(ctx_sni, CS cbinfo->server_cipher_list); | |
3f7eeb86 PP |
604 | #ifdef EXPERIMENTAL_OCSP |
605 | if (cbinfo->ocsp_file) | |
606 | { | |
607 | SSL_CTX_set_tlsext_status_cb(ctx_sni, tls_stapling_cb); | |
608 | SSL_CTX_set_tlsext_status_arg(ctx, cbinfo); | |
609 | } | |
610 | #endif | |
7be682ca | 611 | |
3f7eeb86 | 612 | rc = setup_certs(ctx_sni, tls_verify_certificates, tls_crl, NULL, FALSE); |
7be682ca PP |
613 | if (rc != OK) return SSL_TLSEXT_ERR_NOACK; |
614 | ||
3f7eeb86 PP |
615 | /* do this after setup_certs, because this can require the certs for verifying |
616 | OCSP information. */ | |
617 | rc = tls_expand_session_files(ctx_sni, cbinfo); | |
7be682ca PP |
618 | if (rc != OK) return SSL_TLSEXT_ERR_NOACK; |
619 | ||
620 | DEBUG(D_tls) debug_printf("Switching SSL context.\n"); | |
621 | SSL_set_SSL_CTX(s, ctx_sni); | |
622 | ||
623 | return SSL_TLSEXT_ERR_OK; | |
624 | } | |
3bcbbbe2 | 625 | #endif /* EXIM_HAVE_OPENSSL_TLSEXT */ |
7be682ca PP |
626 | |
627 | ||
628 | ||
629 | ||
3f7eeb86 PP |
630 | #ifdef EXPERIMENTAL_OCSP |
631 | /************************************************* | |
632 | * Callback to handle OCSP Stapling * | |
633 | *************************************************/ | |
634 | ||
635 | /* Called when acting as server during the TLS session setup if the client | |
636 | requests OCSP information with a Certificate Status Request. | |
637 | ||
638 | Documentation via openssl s_server.c and the Apache patch from the OpenSSL | |
639 | project. | |
640 | ||
641 | */ | |
642 | ||
643 | static int | |
644 | tls_stapling_cb(SSL *s, void *arg) | |
645 | { | |
646 | const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg; | |
647 | uschar *response_der; | |
648 | int response_der_len; | |
649 | ||
650 | DEBUG(D_tls) debug_printf("Received TLS status request (OCSP stapling); %s response.\n", | |
651 | cbinfo->ocsp_response ? "have" : "lack"); | |
652 | if (!cbinfo->ocsp_response) | |
653 | return SSL_TLSEXT_ERR_NOACK; | |
654 | ||
655 | response_der = NULL; | |
656 | response_der_len = i2d_OCSP_RESPONSE(cbinfo->ocsp_response, &response_der); | |
657 | if (response_der_len <= 0) | |
658 | return SSL_TLSEXT_ERR_NOACK; | |
659 | ||
660 | SSL_set_tlsext_status_ocsp_resp(ssl, response_der, response_der_len); | |
661 | return SSL_TLSEXT_ERR_OK; | |
662 | } | |
663 | ||
664 | #endif /* EXPERIMENTAL_OCSP */ | |
665 | ||
666 | ||
667 | ||
668 | ||
059ec3d9 PH |
669 | /************************************************* |
670 | * Initialize for TLS * | |
671 | *************************************************/ | |
672 | ||
673 | /* Called from both server and client code, to do preliminary initialization of | |
674 | the library. | |
675 | ||
676 | Arguments: | |
677 | host connected host, if client; NULL if server | |
678 | dhparam DH parameter file | |
679 | certificate certificate file | |
680 | privatekey private key | |
681 | addr address if client; NULL if server (for some randomness) | |
682 | ||
683 | Returns: OK/DEFER/FAIL | |
684 | */ | |
685 | ||
686 | static int | |
c91535f3 | 687 | tls_init(host_item *host, uschar *dhparam, uschar *certificate, |
3f7eeb86 PP |
688 | uschar *privatekey, |
689 | #ifdef EXPERIMENTAL_OCSP | |
690 | uschar *ocsp_file, | |
691 | #endif | |
692 | address_item *addr) | |
059ec3d9 | 693 | { |
77bb000f | 694 | long init_options; |
7be682ca | 695 | int rc; |
77bb000f | 696 | BOOL okay; |
7be682ca PP |
697 | tls_ext_ctx_cb *cbinfo; |
698 | ||
699 | cbinfo = store_malloc(sizeof(tls_ext_ctx_cb)); | |
700 | cbinfo->certificate = certificate; | |
701 | cbinfo->privatekey = privatekey; | |
3f7eeb86 PP |
702 | #ifdef EXPERIMENTAL_OCSP |
703 | cbinfo->ocsp_file = ocsp_file; | |
704 | #endif | |
7be682ca PP |
705 | cbinfo->dhparam = dhparam; |
706 | cbinfo->host = host; | |
77bb000f | 707 | |
059ec3d9 PH |
708 | SSL_load_error_strings(); /* basic set up */ |
709 | OpenSSL_add_ssl_algorithms(); | |
710 | ||
388d6564 | 711 | #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256) |
77bb000f | 712 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the |
a0475b69 TK |
713 | list of available digests. */ |
714 | EVP_add_digest(EVP_sha256()); | |
cf1ef1a9 | 715 | #endif |
a0475b69 | 716 | |
059ec3d9 PH |
717 | /* Create a context */ |
718 | ||
719 | ctx = SSL_CTX_new((host == NULL)? | |
720 | SSLv23_server_method() : SSLv23_client_method()); | |
721 | ||
7199e1ee | 722 | if (ctx == NULL) return tls_error(US"SSL_CTX_new", host, NULL); |
059ec3d9 PH |
723 | |
724 | /* It turns out that we need to seed the random number generator this early in | |
725 | order to get the full complement of ciphers to work. It took me roughly a day | |
726 | of work to discover this by experiment. | |
727 | ||
728 | On systems that have /dev/urandom, SSL may automatically seed itself from | |
729 | there. Otherwise, we have to make something up as best we can. Double check | |
730 | afterwards. */ | |
731 | ||
732 | if (!RAND_status()) | |
733 | { | |
734 | randstuff r; | |
9e3331ea | 735 | gettimeofday(&r.tv, NULL); |
059ec3d9 PH |
736 | r.p = getpid(); |
737 | ||
738 | RAND_seed((uschar *)(&r), sizeof(r)); | |
739 | RAND_seed((uschar *)big_buffer, big_buffer_size); | |
740 | if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr)); | |
741 | ||
742 | if (!RAND_status()) | |
7199e1ee | 743 | return tls_error(US"RAND_status", host, |
5ca6d115 | 744 | US"unable to seed random number generator"); |
059ec3d9 PH |
745 | } |
746 | ||
747 | /* Set up the information callback, which outputs if debugging is at a suitable | |
748 | level. */ | |
749 | ||
58c01c94 | 750 | SSL_CTX_set_info_callback(ctx, (void (*)())info_callback); |
059ec3d9 | 751 | |
c80c5570 PP |
752 | /* Automatically re-try reads/writes after renegotiation. */ |
753 | (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY); | |
754 | ||
77bb000f PP |
755 | /* Apply administrator-supplied work-arounds. |
756 | Historically we applied just one requested option, | |
757 | SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we | |
758 | moved to an administrator-controlled list of options to specify and | |
759 | grandfathered in the first one as the default value for "openssl_options". | |
059ec3d9 | 760 | |
77bb000f PP |
761 | No OpenSSL version number checks: the options we accept depend upon the |
762 | availability of the option value macros from OpenSSL. */ | |
059ec3d9 | 763 | |
77bb000f PP |
764 | okay = tls_openssl_options_parse(openssl_options, &init_options); |
765 | if (!okay) | |
73a46702 | 766 | return tls_error(US"openssl_options parsing failed", host, NULL); |
77bb000f PP |
767 | |
768 | if (init_options) | |
769 | { | |
770 | DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options); | |
771 | if (!(SSL_CTX_set_options(ctx, init_options))) | |
772 | return tls_error(string_sprintf( | |
773 | "SSL_CTX_set_option(%#lx)", init_options), host, NULL); | |
774 | } | |
775 | else | |
776 | DEBUG(D_tls) debug_printf("no SSL CTX options to set\n"); | |
059ec3d9 PH |
777 | |
778 | /* Initialize with DH parameters if supplied */ | |
779 | ||
7199e1ee | 780 | if (!init_dh(dhparam, host)) return DEFER; |
059ec3d9 | 781 | |
3f7eeb86 | 782 | /* Set up certificate and key (and perhaps OCSP info) */ |
059ec3d9 | 783 | |
7be682ca PP |
784 | rc = tls_expand_session_files(ctx, cbinfo); |
785 | if (rc != OK) return rc; | |
c91535f3 | 786 | |
7be682ca | 787 | /* If we need to handle SNI, do so */ |
3bcbbbe2 | 788 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
3f0945ff PP |
789 | if (host == NULL) |
790 | { | |
3f7eeb86 PP |
791 | #ifdef EXPERIMENTAL_OCSP |
792 | /* We check ocsp_file, not ocsp_response, because we care about if | |
793 | the option exists, not what the current expansion might be, as SNI might | |
794 | change the certificate and OCSP file in use between now and the time the | |
795 | callback is invoked. */ | |
796 | if (cbinfo->ocsp_file) | |
797 | { | |
798 | SSL_CTX_set_tlsext_status_cb(ctx, tls_stapling_cb); | |
799 | SSL_CTX_set_tlsext_status_arg(ctx, cbinfo); | |
800 | } | |
801 | #endif | |
3f0945ff PP |
802 | /* We always do this, so that $tls_sni is available even if not used in |
803 | tls_certificate */ | |
804 | SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb); | |
805 | SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo); | |
806 | } | |
7be682ca | 807 | #endif |
059ec3d9 PH |
808 | |
809 | /* Set up the RSA callback */ | |
810 | ||
811 | SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback); | |
812 | ||
813 | /* Finally, set the timeout, and we are done */ | |
814 | ||
815 | SSL_CTX_set_timeout(ctx, ssl_session_timeout); | |
816 | DEBUG(D_tls) debug_printf("Initialized TLS\n"); | |
7be682ca PP |
817 | |
818 | static_cbinfo = cbinfo; | |
819 | ||
059ec3d9 PH |
820 | return OK; |
821 | } | |
822 | ||
823 | ||
824 | ||
825 | ||
826 | /************************************************* | |
827 | * Get name of cipher in use * | |
828 | *************************************************/ | |
829 | ||
830 | /* The answer is left in a static buffer, and tls_cipher is set to point | |
831 | to it. | |
832 | ||
833 | Argument: pointer to an SSL structure for the connection | |
834 | Returns: nothing | |
835 | */ | |
836 | ||
837 | static void | |
838 | construct_cipher_name(SSL *ssl) | |
839 | { | |
840 | static uschar cipherbuf[256]; | |
57b3a7f5 PP |
841 | /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't |
842 | yet reflect that. It should be a safe change anyway, even 0.9.8 versions have | |
843 | the accessor functions use const in the prototype. */ | |
844 | const SSL_CIPHER *c; | |
059ec3d9 | 845 | uschar *ver; |
059ec3d9 PH |
846 | |
847 | switch (ssl->session->ssl_version) | |
848 | { | |
849 | case SSL2_VERSION: | |
850 | ver = US"SSLv2"; | |
851 | break; | |
852 | ||
853 | case SSL3_VERSION: | |
854 | ver = US"SSLv3"; | |
855 | break; | |
856 | ||
857 | case TLS1_VERSION: | |
858 | ver = US"TLSv1"; | |
859 | break; | |
860 | ||
c80c5570 PP |
861 | #ifdef TLS1_1_VERSION |
862 | case TLS1_1_VERSION: | |
863 | ver = US"TLSv1.1"; | |
864 | break; | |
865 | #endif | |
866 | ||
867 | #ifdef TLS1_2_VERSION | |
868 | case TLS1_2_VERSION: | |
869 | ver = US"TLSv1.2"; | |
870 | break; | |
871 | #endif | |
872 | ||
059ec3d9 PH |
873 | default: |
874 | ver = US"UNKNOWN"; | |
875 | } | |
876 | ||
57b3a7f5 | 877 | c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl); |
edc33b5f | 878 | SSL_CIPHER_get_bits(c, &tls_bits); |
059ec3d9 PH |
879 | |
880 | string_format(cipherbuf, sizeof(cipherbuf), "%s:%s:%u", ver, | |
edc33b5f | 881 | SSL_CIPHER_get_name(c), tls_bits); |
059ec3d9 PH |
882 | tls_cipher = cipherbuf; |
883 | ||
884 | DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf); | |
885 | } | |
886 | ||
887 | ||
888 | ||
889 | ||
890 | ||
891 | /************************************************* | |
892 | * Set up for verifying certificates * | |
893 | *************************************************/ | |
894 | ||
895 | /* Called by both client and server startup | |
896 | ||
897 | Arguments: | |
7be682ca | 898 | sctx SSL_CTX* to initialise |
059ec3d9 PH |
899 | certs certs file or NULL |
900 | crl CRL file or NULL | |
901 | host NULL in a server; the remote host in a client | |
902 | optional TRUE if called from a server for a host in tls_try_verify_hosts; | |
903 | otherwise passed as FALSE | |
904 | ||
905 | Returns: OK/DEFER/FAIL | |
906 | */ | |
907 | ||
908 | static int | |
7be682ca | 909 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional) |
059ec3d9 PH |
910 | { |
911 | uschar *expcerts, *expcrl; | |
912 | ||
913 | if (!expand_check(certs, US"tls_verify_certificates", &expcerts)) | |
914 | return DEFER; | |
915 | ||
916 | if (expcerts != NULL) | |
917 | { | |
918 | struct stat statbuf; | |
7be682ca | 919 | if (!SSL_CTX_set_default_verify_paths(sctx)) |
7199e1ee | 920 | return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL); |
059ec3d9 PH |
921 | |
922 | if (Ustat(expcerts, &statbuf) < 0) | |
923 | { | |
924 | log_write(0, LOG_MAIN|LOG_PANIC, | |
925 | "failed to stat %s for certificates", expcerts); | |
926 | return DEFER; | |
927 | } | |
928 | else | |
929 | { | |
930 | uschar *file, *dir; | |
931 | if ((statbuf.st_mode & S_IFMT) == S_IFDIR) | |
932 | { file = NULL; dir = expcerts; } | |
933 | else | |
934 | { file = expcerts; dir = NULL; } | |
935 | ||
936 | /* If a certificate file is empty, the next function fails with an | |
937 | unhelpful error message. If we skip it, we get the correct behaviour (no | |
938 | certificates are recognized, but the error message is still misleading (it | |
939 | says no certificate was supplied.) But this is better. */ | |
940 | ||
941 | if ((file == NULL || statbuf.st_size > 0) && | |
7be682ca | 942 | !SSL_CTX_load_verify_locations(sctx, CS file, CS dir)) |
7199e1ee | 943 | return tls_error(US"SSL_CTX_load_verify_locations", host, NULL); |
059ec3d9 PH |
944 | |
945 | if (file != NULL) | |
946 | { | |
7be682ca | 947 | SSL_CTX_set_client_CA_list(sctx, SSL_load_client_CA_file(CS file)); |
059ec3d9 PH |
948 | } |
949 | } | |
950 | ||
951 | /* Handle a certificate revocation list. */ | |
952 | ||
953 | #if OPENSSL_VERSION_NUMBER > 0x00907000L | |
954 | ||
8b417f2c PH |
955 | /* This bit of code is now the version supplied by Lars Mainka. (I have |
956 | * merely reformatted it into the Exim code style.) | |
957 | ||
958 | * "From here I changed the code to add support for multiple crl's | |
959 | * in pem format in one file or to support hashed directory entries in | |
960 | * pem format instead of a file. This method now uses the library function | |
961 | * X509_STORE_load_locations to add the CRL location to the SSL context. | |
962 | * OpenSSL will then handle the verify against CA certs and CRLs by | |
963 | * itself in the verify callback." */ | |
964 | ||
059ec3d9 PH |
965 | if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER; |
966 | if (expcrl != NULL && *expcrl != 0) | |
967 | { | |
8b417f2c PH |
968 | struct stat statbufcrl; |
969 | if (Ustat(expcrl, &statbufcrl) < 0) | |
970 | { | |
971 | log_write(0, LOG_MAIN|LOG_PANIC, | |
972 | "failed to stat %s for certificates revocation lists", expcrl); | |
973 | return DEFER; | |
974 | } | |
975 | else | |
059ec3d9 | 976 | { |
8b417f2c PH |
977 | /* is it a file or directory? */ |
978 | uschar *file, *dir; | |
7be682ca | 979 | X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx); |
8b417f2c | 980 | if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR) |
059ec3d9 | 981 | { |
8b417f2c PH |
982 | file = NULL; |
983 | dir = expcrl; | |
984 | DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir); | |
059ec3d9 PH |
985 | } |
986 | else | |
987 | { | |
8b417f2c PH |
988 | file = expcrl; |
989 | dir = NULL; | |
990 | DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file); | |
059ec3d9 | 991 | } |
8b417f2c | 992 | if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0) |
7199e1ee | 993 | return tls_error(US"X509_STORE_load_locations", host, NULL); |
8b417f2c PH |
994 | |
995 | /* setting the flags to check against the complete crl chain */ | |
996 | ||
997 | X509_STORE_set_flags(cvstore, | |
998 | X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL); | |
059ec3d9 | 999 | } |
059ec3d9 PH |
1000 | } |
1001 | ||
1002 | #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */ | |
1003 | ||
1004 | /* If verification is optional, don't fail if no certificate */ | |
1005 | ||
7be682ca | 1006 | SSL_CTX_set_verify(sctx, |
059ec3d9 PH |
1007 | SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT), |
1008 | verify_callback); | |
1009 | } | |
1010 | ||
1011 | return OK; | |
1012 | } | |
1013 | ||
1014 | ||
1015 | ||
1016 | /************************************************* | |
1017 | * Start a TLS session in a server * | |
1018 | *************************************************/ | |
1019 | ||
1020 | /* This is called when Exim is running as a server, after having received | |
1021 | the STARTTLS command. It must respond to that command, and then negotiate | |
1022 | a TLS session. | |
1023 | ||
1024 | Arguments: | |
1025 | require_ciphers allowed ciphers | |
1026 | ||
1027 | Returns: OK on success | |
1028 | DEFER for errors before the start of the negotiation | |
1029 | FAIL for errors during the negotation; the server can't | |
1030 | continue running. | |
1031 | */ | |
1032 | ||
1033 | int | |
17c76198 | 1034 | tls_server_start(const uschar *require_ciphers) |
059ec3d9 PH |
1035 | { |
1036 | int rc; | |
1037 | uschar *expciphers; | |
7be682ca | 1038 | tls_ext_ctx_cb *cbinfo; |
059ec3d9 PH |
1039 | |
1040 | /* Check for previous activation */ | |
1041 | ||
1042 | if (tls_active >= 0) | |
1043 | { | |
5ca6d115 | 1044 | tls_error(US"STARTTLS received after TLS started", NULL, US""); |
059ec3d9 PH |
1045 | smtp_printf("554 Already in TLS\r\n"); |
1046 | return FAIL; | |
1047 | } | |
1048 | ||
1049 | /* Initialize the SSL library. If it fails, it will already have logged | |
1050 | the error. */ | |
1051 | ||
3f7eeb86 PP |
1052 | rc = tls_init(NULL, tls_dhparam, tls_certificate, tls_privatekey, |
1053 | #ifdef EXPERIMENTAL_OCSP | |
1054 | tls_ocsp_file, | |
1055 | #endif | |
1056 | NULL); | |
059ec3d9 | 1057 | if (rc != OK) return rc; |
7be682ca | 1058 | cbinfo = static_cbinfo; |
059ec3d9 PH |
1059 | |
1060 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers)) | |
1061 | return FAIL; | |
1062 | ||
1063 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they | |
17c76198 PP |
1064 | were historically separated by underscores. So that I can use either form in my |
1065 | tests, and also for general convenience, we turn underscores into hyphens here. | |
1066 | */ | |
059ec3d9 PH |
1067 | |
1068 | if (expciphers != NULL) | |
1069 | { | |
1070 | uschar *s = expciphers; | |
1071 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } | |
1072 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); | |
1073 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) | |
7199e1ee | 1074 | return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL); |
7be682ca | 1075 | cbinfo->server_cipher_list = expciphers; |
059ec3d9 PH |
1076 | } |
1077 | ||
1078 | /* If this is a host for which certificate verification is mandatory or | |
1079 | optional, set up appropriately. */ | |
1080 | ||
1081 | tls_certificate_verified = FALSE; | |
1082 | verify_callback_called = FALSE; | |
1083 | ||
1084 | if (verify_check_host(&tls_verify_hosts) == OK) | |
1085 | { | |
7be682ca | 1086 | rc = setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, FALSE); |
059ec3d9 PH |
1087 | if (rc != OK) return rc; |
1088 | verify_optional = FALSE; | |
1089 | } | |
1090 | else if (verify_check_host(&tls_try_verify_hosts) == OK) | |
1091 | { | |
7be682ca | 1092 | rc = setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, TRUE); |
059ec3d9 PH |
1093 | if (rc != OK) return rc; |
1094 | verify_optional = TRUE; | |
1095 | } | |
1096 | ||
1097 | /* Prepare for new connection */ | |
1098 | ||
7199e1ee | 1099 | if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL); |
da3ad30d PP |
1100 | |
1101 | /* Warning: we used to SSL_clear(ssl) here, it was removed. | |
1102 | * | |
1103 | * With the SSL_clear(), we get strange interoperability bugs with | |
1104 | * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in | |
1105 | * OpenSSL itself, as a clear should not lead to inability to follow protocols. | |
1106 | * | |
1107 | * The SSL_clear() call is to let an existing SSL* be reused, typically after | |
1108 | * session shutdown. In this case, we have a brand new object and there's no | |
1109 | * obvious reason to immediately clear it. I'm guessing that this was | |
1110 | * originally added because of incomplete initialisation which the clear fixed, | |
1111 | * in some historic release. | |
1112 | */ | |
059ec3d9 PH |
1113 | |
1114 | /* Set context and tell client to go ahead, except in the case of TLS startup | |
1115 | on connection, where outputting anything now upsets the clients and tends to | |
1116 | make them disconnect. We need to have an explicit fflush() here, to force out | |
1117 | the response. Other smtp_printf() calls do not need it, because in non-TLS | |
1118 | mode, the fflush() happens when smtp_getc() is called. */ | |
1119 | ||
1120 | SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx)); | |
1121 | if (!tls_on_connect) | |
1122 | { | |
1123 | smtp_printf("220 TLS go ahead\r\n"); | |
1124 | fflush(smtp_out); | |
1125 | } | |
1126 | ||
1127 | /* Now negotiate the TLS session. We put our own timer on it, since it seems | |
1128 | that the OpenSSL library doesn't. */ | |
1129 | ||
56f5d9bd PH |
1130 | SSL_set_wfd(ssl, fileno(smtp_out)); |
1131 | SSL_set_rfd(ssl, fileno(smtp_in)); | |
059ec3d9 PH |
1132 | SSL_set_accept_state(ssl); |
1133 | ||
1134 | DEBUG(D_tls) debug_printf("Calling SSL_accept\n"); | |
1135 | ||
1136 | sigalrm_seen = FALSE; | |
1137 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
1138 | rc = SSL_accept(ssl); | |
1139 | alarm(0); | |
1140 | ||
1141 | if (rc <= 0) | |
1142 | { | |
7199e1ee | 1143 | tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL); |
77bb000f PP |
1144 | if (ERR_get_error() == 0) |
1145 | log_write(0, LOG_MAIN, | |
a053d125 | 1146 | "TLS client disconnected cleanly (rejected our certificate?)"); |
059ec3d9 PH |
1147 | return FAIL; |
1148 | } | |
1149 | ||
1150 | DEBUG(D_tls) debug_printf("SSL_accept was successful\n"); | |
1151 | ||
1152 | /* TLS has been set up. Adjust the input functions to read via TLS, | |
1153 | and initialize things. */ | |
1154 | ||
1155 | construct_cipher_name(ssl); | |
1156 | ||
1157 | DEBUG(D_tls) | |
1158 | { | |
1159 | uschar buf[2048]; | |
1160 | if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)) != NULL) | |
1161 | debug_printf("Shared ciphers: %s\n", buf); | |
1162 | } | |
1163 | ||
1164 | ||
1165 | ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size); | |
1166 | ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0; | |
1167 | ssl_xfer_eof = ssl_xfer_error = 0; | |
1168 | ||
1169 | receive_getc = tls_getc; | |
1170 | receive_ungetc = tls_ungetc; | |
1171 | receive_feof = tls_feof; | |
1172 | receive_ferror = tls_ferror; | |
58eb016e | 1173 | receive_smtp_buffered = tls_smtp_buffered; |
059ec3d9 PH |
1174 | |
1175 | tls_active = fileno(smtp_out); | |
1176 | return OK; | |
1177 | } | |
1178 | ||
1179 | ||
1180 | ||
1181 | ||
1182 | ||
1183 | /************************************************* | |
1184 | * Start a TLS session in a client * | |
1185 | *************************************************/ | |
1186 | ||
1187 | /* Called from the smtp transport after STARTTLS has been accepted. | |
1188 | ||
1189 | Argument: | |
1190 | fd the fd of the connection | |
1191 | host connected host (for messages) | |
83da1223 | 1192 | addr the first address |
059ec3d9 PH |
1193 | dhparam DH parameter file |
1194 | certificate certificate file | |
1195 | privatekey private key file | |
3f0945ff | 1196 | sni TLS SNI to send to remote host |
059ec3d9 PH |
1197 | verify_certs file for certificate verify |
1198 | crl file containing CRL | |
1199 | require_ciphers list of allowed ciphers | |
83da1223 | 1200 | timeout startup timeout |
059ec3d9 PH |
1201 | |
1202 | Returns: OK on success | |
1203 | FAIL otherwise - note that tls_error() will not give DEFER | |
1204 | because this is not a server | |
1205 | */ | |
1206 | ||
1207 | int | |
1208 | tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam, | |
3f0945ff PP |
1209 | uschar *certificate, uschar *privatekey, uschar *sni, |
1210 | uschar *verify_certs, uschar *crl, | |
17c76198 | 1211 | uschar *require_ciphers, int timeout) |
059ec3d9 PH |
1212 | { |
1213 | static uschar txt[256]; | |
1214 | uschar *expciphers; | |
1215 | X509* server_cert; | |
1216 | int rc; | |
1217 | ||
3f7eeb86 PP |
1218 | rc = tls_init(host, dhparam, certificate, privatekey, |
1219 | #ifdef EXPERIMENTAL_OCSP | |
1220 | NULL, | |
1221 | #endif | |
1222 | addr); | |
059ec3d9 PH |
1223 | if (rc != OK) return rc; |
1224 | ||
1225 | tls_certificate_verified = FALSE; | |
1226 | verify_callback_called = FALSE; | |
1227 | ||
1228 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers)) | |
1229 | return FAIL; | |
1230 | ||
1231 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they | |
1232 | are separated by underscores. So that I can use either form in my tests, and | |
1233 | also for general convenience, we turn underscores into hyphens here. */ | |
1234 | ||
1235 | if (expciphers != NULL) | |
1236 | { | |
1237 | uschar *s = expciphers; | |
1238 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } | |
1239 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); | |
1240 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) | |
7199e1ee | 1241 | return tls_error(US"SSL_CTX_set_cipher_list", host, NULL); |
059ec3d9 PH |
1242 | } |
1243 | ||
7be682ca | 1244 | rc = setup_certs(ctx, verify_certs, crl, host, FALSE); |
059ec3d9 PH |
1245 | if (rc != OK) return rc; |
1246 | ||
7199e1ee | 1247 | if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", host, NULL); |
059ec3d9 PH |
1248 | SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx)); |
1249 | SSL_set_fd(ssl, fd); | |
1250 | SSL_set_connect_state(ssl); | |
1251 | ||
3f0945ff PP |
1252 | if (sni) |
1253 | { | |
1254 | if (!expand_check(sni, US"tls_sni", &tls_sni)) | |
1255 | return FAIL; | |
1256 | if (!Ustrlen(tls_sni)) | |
1257 | tls_sni = NULL; | |
1258 | else | |
1259 | { | |
1260 | DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_sni); | |
1261 | SSL_set_tlsext_host_name(ssl, tls_sni); | |
1262 | } | |
1263 | } | |
1264 | ||
059ec3d9 PH |
1265 | /* There doesn't seem to be a built-in timeout on connection. */ |
1266 | ||
1267 | DEBUG(D_tls) debug_printf("Calling SSL_connect\n"); | |
1268 | sigalrm_seen = FALSE; | |
1269 | alarm(timeout); | |
1270 | rc = SSL_connect(ssl); | |
1271 | alarm(0); | |
1272 | ||
1273 | if (rc <= 0) | |
7199e1ee | 1274 | return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL); |
059ec3d9 PH |
1275 | |
1276 | DEBUG(D_tls) debug_printf("SSL_connect succeeded\n"); | |
1277 | ||
453a6645 | 1278 | /* Beware anonymous ciphers which lead to server_cert being NULL */ |
059ec3d9 | 1279 | server_cert = SSL_get_peer_certificate (ssl); |
453a6645 PP |
1280 | if (server_cert) |
1281 | { | |
1282 | tls_peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert), | |
1283 | CS txt, sizeof(txt)); | |
1284 | tls_peerdn = txt; | |
1285 | } | |
1286 | else | |
1287 | tls_peerdn = NULL; | |
059ec3d9 PH |
1288 | |
1289 | construct_cipher_name(ssl); /* Sets tls_cipher */ | |
1290 | ||
1291 | tls_active = fd; | |
1292 | return OK; | |
1293 | } | |
1294 | ||
1295 | ||
1296 | ||
1297 | ||
1298 | ||
1299 | /************************************************* | |
1300 | * TLS version of getc * | |
1301 | *************************************************/ | |
1302 | ||
1303 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, | |
1304 | it refills the buffer via the SSL reading function. | |
1305 | ||
1306 | Arguments: none | |
1307 | Returns: the next character or EOF | |
1308 | */ | |
1309 | ||
1310 | int | |
1311 | tls_getc(void) | |
1312 | { | |
1313 | if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm) | |
1314 | { | |
1315 | int error; | |
1316 | int inbytes; | |
1317 | ||
c80c5570 PP |
1318 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl, |
1319 | ssl_xfer_buffer, ssl_xfer_buffer_size); | |
059ec3d9 PH |
1320 | |
1321 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
1322 | inbytes = SSL_read(ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size); | |
1323 | error = SSL_get_error(ssl, inbytes); | |
1324 | alarm(0); | |
1325 | ||
1326 | /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been | |
1327 | closed down, not that the socket itself has been closed down. Revert to | |
1328 | non-SSL handling. */ | |
1329 | ||
1330 | if (error == SSL_ERROR_ZERO_RETURN) | |
1331 | { | |
1332 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); | |
1333 | ||
1334 | receive_getc = smtp_getc; | |
1335 | receive_ungetc = smtp_ungetc; | |
1336 | receive_feof = smtp_feof; | |
1337 | receive_ferror = smtp_ferror; | |
58eb016e | 1338 | receive_smtp_buffered = smtp_buffered; |
059ec3d9 PH |
1339 | |
1340 | SSL_free(ssl); | |
1341 | ssl = NULL; | |
1342 | tls_active = -1; | |
3f0945ff | 1343 | tls_bits = 0; |
059ec3d9 PH |
1344 | tls_cipher = NULL; |
1345 | tls_peerdn = NULL; | |
3f0945ff | 1346 | tls_sni = NULL; |
059ec3d9 PH |
1347 | |
1348 | return smtp_getc(); | |
1349 | } | |
1350 | ||
1351 | /* Handle genuine errors */ | |
1352 | ||
ba084640 PP |
1353 | else if (error == SSL_ERROR_SSL) |
1354 | { | |
1355 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
89dd51cd | 1356 | log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring); |
ba084640 PP |
1357 | ssl_xfer_error = 1; |
1358 | return EOF; | |
1359 | } | |
1360 | ||
059ec3d9 PH |
1361 | else if (error != SSL_ERROR_NONE) |
1362 | { | |
1363 | DEBUG(D_tls) debug_printf("Got SSL error %d\n", error); | |
1364 | ssl_xfer_error = 1; | |
1365 | return EOF; | |
1366 | } | |
c80c5570 | 1367 | |
80a47a2c TK |
1368 | #ifndef DISABLE_DKIM |
1369 | dkim_exim_verify_feed(ssl_xfer_buffer, inbytes); | |
1370 | #endif | |
059ec3d9 PH |
1371 | ssl_xfer_buffer_hwm = inbytes; |
1372 | ssl_xfer_buffer_lwm = 0; | |
1373 | } | |
1374 | ||
1375 | /* Something in the buffer; return next uschar */ | |
1376 | ||
1377 | return ssl_xfer_buffer[ssl_xfer_buffer_lwm++]; | |
1378 | } | |
1379 | ||
1380 | ||
1381 | ||
1382 | /************************************************* | |
1383 | * Read bytes from TLS channel * | |
1384 | *************************************************/ | |
1385 | ||
1386 | /* | |
1387 | Arguments: | |
1388 | buff buffer of data | |
1389 | len size of buffer | |
1390 | ||
1391 | Returns: the number of bytes read | |
1392 | -1 after a failed read | |
1393 | */ | |
1394 | ||
1395 | int | |
1396 | tls_read(uschar *buff, size_t len) | |
1397 | { | |
1398 | int inbytes; | |
1399 | int error; | |
1400 | ||
c80c5570 PP |
1401 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl, |
1402 | buff, (unsigned int)len); | |
059ec3d9 PH |
1403 | |
1404 | inbytes = SSL_read(ssl, CS buff, len); | |
1405 | error = SSL_get_error(ssl, inbytes); | |
1406 | ||
1407 | if (error == SSL_ERROR_ZERO_RETURN) | |
1408 | { | |
1409 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); | |
1410 | return -1; | |
1411 | } | |
1412 | else if (error != SSL_ERROR_NONE) | |
1413 | { | |
1414 | return -1; | |
1415 | } | |
1416 | ||
1417 | return inbytes; | |
1418 | } | |
1419 | ||
1420 | ||
1421 | ||
1422 | ||
1423 | ||
1424 | /************************************************* | |
1425 | * Write bytes down TLS channel * | |
1426 | *************************************************/ | |
1427 | ||
1428 | /* | |
1429 | Arguments: | |
1430 | buff buffer of data | |
1431 | len number of bytes | |
1432 | ||
1433 | Returns: the number of bytes after a successful write, | |
1434 | -1 after a failed write | |
1435 | */ | |
1436 | ||
1437 | int | |
1438 | tls_write(const uschar *buff, size_t len) | |
1439 | { | |
1440 | int outbytes; | |
1441 | int error; | |
1442 | int left = len; | |
1443 | ||
c80c5570 | 1444 | DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left); |
059ec3d9 PH |
1445 | while (left > 0) |
1446 | { | |
c80c5570 | 1447 | DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left); |
059ec3d9 PH |
1448 | outbytes = SSL_write(ssl, CS buff, left); |
1449 | error = SSL_get_error(ssl, outbytes); | |
1450 | DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error); | |
1451 | switch (error) | |
1452 | { | |
1453 | case SSL_ERROR_SSL: | |
1454 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
1455 | log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring); | |
1456 | return -1; | |
1457 | ||
1458 | case SSL_ERROR_NONE: | |
1459 | left -= outbytes; | |
1460 | buff += outbytes; | |
1461 | break; | |
1462 | ||
1463 | case SSL_ERROR_ZERO_RETURN: | |
1464 | log_write(0, LOG_MAIN, "SSL channel closed on write"); | |
1465 | return -1; | |
1466 | ||
1467 | default: | |
1468 | log_write(0, LOG_MAIN, "SSL_write error %d", error); | |
1469 | return -1; | |
1470 | } | |
1471 | } | |
1472 | return len; | |
1473 | } | |
1474 | ||
1475 | ||
1476 | ||
1477 | /************************************************* | |
1478 | * Close down a TLS session * | |
1479 | *************************************************/ | |
1480 | ||
1481 | /* This is also called from within a delivery subprocess forked from the | |
1482 | daemon, to shut down the TLS library, without actually doing a shutdown (which | |
1483 | would tamper with the SSL session in the parent process). | |
1484 | ||
1485 | Arguments: TRUE if SSL_shutdown is to be called | |
1486 | Returns: nothing | |
1487 | */ | |
1488 | ||
1489 | void | |
1490 | tls_close(BOOL shutdown) | |
1491 | { | |
1492 | if (tls_active < 0) return; /* TLS was not active */ | |
1493 | ||
1494 | if (shutdown) | |
1495 | { | |
1496 | DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n"); | |
1497 | SSL_shutdown(ssl); | |
1498 | } | |
1499 | ||
1500 | SSL_free(ssl); | |
1501 | ssl = NULL; | |
1502 | ||
1503 | tls_active = -1; | |
1504 | } | |
1505 | ||
36f12725 NM |
1506 | |
1507 | ||
1508 | ||
3375e053 PP |
1509 | /************************************************* |
1510 | * Let tls_require_ciphers be checked at startup * | |
1511 | *************************************************/ | |
1512 | ||
1513 | /* The tls_require_ciphers option, if set, must be something which the | |
1514 | library can parse. | |
1515 | ||
1516 | Returns: NULL on success, or error message | |
1517 | */ | |
1518 | ||
1519 | uschar * | |
1520 | tls_validate_require_cipher(void) | |
1521 | { | |
1522 | SSL_CTX *ctx; | |
1523 | uschar *s, *expciphers, *err; | |
1524 | ||
1525 | /* this duplicates from tls_init(), we need a better "init just global | |
1526 | state, for no specific purpose" singleton function of our own */ | |
1527 | ||
1528 | SSL_load_error_strings(); | |
1529 | OpenSSL_add_ssl_algorithms(); | |
1530 | #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256) | |
1531 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the | |
1532 | list of available digests. */ | |
1533 | EVP_add_digest(EVP_sha256()); | |
1534 | #endif | |
1535 | ||
1536 | if (!(tls_require_ciphers && *tls_require_ciphers)) | |
1537 | return NULL; | |
1538 | ||
1539 | if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers)) | |
1540 | return US"failed to expand tls_require_ciphers"; | |
1541 | ||
1542 | if (!(expciphers && *expciphers)) | |
1543 | return NULL; | |
1544 | ||
1545 | /* normalisation ripped from above */ | |
1546 | s = expciphers; | |
1547 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } | |
1548 | ||
1549 | err = NULL; | |
1550 | ||
1551 | ctx = SSL_CTX_new(SSLv23_server_method()); | |
1552 | if (!ctx) | |
1553 | { | |
1554 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
1555 | return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring); | |
1556 | } | |
1557 | ||
1558 | DEBUG(D_tls) | |
1559 | debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers); | |
1560 | ||
1561 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) | |
1562 | { | |
1563 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
1564 | err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers); | |
1565 | } | |
1566 | ||
1567 | SSL_CTX_free(ctx); | |
1568 | ||
1569 | return err; | |
1570 | } | |
1571 | ||
1572 | ||
1573 | ||
1574 | ||
36f12725 NM |
1575 | /************************************************* |
1576 | * Report the library versions. * | |
1577 | *************************************************/ | |
1578 | ||
1579 | /* There have historically been some issues with binary compatibility in | |
1580 | OpenSSL libraries; if Exim (like many other applications) is built against | |
1581 | one version of OpenSSL but the run-time linker picks up another version, | |
1582 | it can result in serious failures, including crashing with a SIGSEGV. So | |
1583 | report the version found by the compiler and the run-time version. | |
1584 | ||
1585 | Arguments: a FILE* to print the results to | |
1586 | Returns: nothing | |
1587 | */ | |
1588 | ||
1589 | void | |
1590 | tls_version_report(FILE *f) | |
1591 | { | |
754a0503 PP |
1592 | fprintf(f, "Library version: OpenSSL: Compile: %s\n" |
1593 | " Runtime: %s\n", | |
1594 | OPENSSL_VERSION_TEXT, | |
1595 | SSLeay_version(SSLEAY_VERSION)); | |
36f12725 NM |
1596 | } |
1597 | ||
9e3331ea TK |
1598 | |
1599 | ||
1600 | ||
1601 | /************************************************* | |
17c76198 | 1602 | * Random number generation * |
9e3331ea TK |
1603 | *************************************************/ |
1604 | ||
1605 | /* Pseudo-random number generation. The result is not expected to be | |
1606 | cryptographically strong but not so weak that someone will shoot themselves | |
1607 | in the foot using it as a nonce in input in some email header scheme or | |
1608 | whatever weirdness they'll twist this into. The result should handle fork() | |
1609 | and avoid repeating sequences. OpenSSL handles that for us. | |
1610 | ||
1611 | Arguments: | |
1612 | max range maximum | |
1613 | Returns a random number in range [0, max-1] | |
1614 | */ | |
1615 | ||
1616 | int | |
17c76198 | 1617 | vaguely_random_number(int max) |
9e3331ea TK |
1618 | { |
1619 | unsigned int r; | |
1620 | int i, needed_len; | |
1621 | uschar *p; | |
1622 | uschar smallbuf[sizeof(r)]; | |
1623 | ||
1624 | if (max <= 1) | |
1625 | return 0; | |
1626 | ||
1627 | /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */ | |
1628 | if (!RAND_status()) | |
1629 | { | |
1630 | randstuff r; | |
1631 | gettimeofday(&r.tv, NULL); | |
1632 | r.p = getpid(); | |
1633 | ||
1634 | RAND_seed((uschar *)(&r), sizeof(r)); | |
1635 | } | |
1636 | /* We're after pseudo-random, not random; if we still don't have enough data | |
1637 | in the internal PRNG then our options are limited. We could sleep and hope | |
1638 | for entropy to come along (prayer technique) but if the system is so depleted | |
1639 | in the first place then something is likely to just keep taking it. Instead, | |
1640 | we'll just take whatever little bit of pseudo-random we can still manage to | |
1641 | get. */ | |
1642 | ||
1643 | needed_len = sizeof(r); | |
1644 | /* Don't take 8 times more entropy than needed if int is 8 octets and we were | |
1645 | asked for a number less than 10. */ | |
1646 | for (r = max, i = 0; r; ++i) | |
1647 | r >>= 1; | |
1648 | i = (i + 7) / 8; | |
1649 | if (i < needed_len) | |
1650 | needed_len = i; | |
1651 | ||
1652 | /* We do not care if crypto-strong */ | |
17c76198 PP |
1653 | i = RAND_pseudo_bytes(smallbuf, needed_len); |
1654 | if (i < 0) | |
1655 | { | |
1656 | DEBUG(D_all) | |
1657 | debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n"); | |
1658 | return vaguely_random_number_fallback(max); | |
1659 | } | |
1660 | ||
9e3331ea TK |
1661 | r = 0; |
1662 | for (p = smallbuf; needed_len; --needed_len, ++p) | |
1663 | { | |
1664 | r *= 256; | |
1665 | r += *p; | |
1666 | } | |
1667 | ||
1668 | /* We don't particularly care about weighted results; if someone wants | |
1669 | smooth distribution and cares enough then they should submit a patch then. */ | |
1670 | return r % max; | |
1671 | } | |
1672 | ||
77bb000f PP |
1673 | |
1674 | ||
1675 | ||
1676 | /************************************************* | |
1677 | * OpenSSL option parse * | |
1678 | *************************************************/ | |
1679 | ||
1680 | /* Parse one option for tls_openssl_options_parse below | |
1681 | ||
1682 | Arguments: | |
1683 | name one option name | |
1684 | value place to store a value for it | |
1685 | Returns success or failure in parsing | |
1686 | */ | |
1687 | ||
1688 | struct exim_openssl_option { | |
1689 | uschar *name; | |
1690 | long value; | |
1691 | }; | |
1692 | /* We could use a macro to expand, but we need the ifdef and not all the | |
1693 | options document which version they were introduced in. Policylet: include | |
1694 | all options unless explicitly for DTLS, let the administrator choose which | |
1695 | to apply. | |
1696 | ||
1697 | This list is current as of: | |
c80c5570 | 1698 | ==> 1.0.1b <== */ |
77bb000f PP |
1699 | static struct exim_openssl_option exim_openssl_options[] = { |
1700 | /* KEEP SORTED ALPHABETICALLY! */ | |
1701 | #ifdef SSL_OP_ALL | |
73a46702 | 1702 | { US"all", SSL_OP_ALL }, |
77bb000f PP |
1703 | #endif |
1704 | #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION | |
73a46702 | 1705 | { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION }, |
77bb000f PP |
1706 | #endif |
1707 | #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE | |
73a46702 | 1708 | { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE }, |
77bb000f PP |
1709 | #endif |
1710 | #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS | |
73a46702 | 1711 | { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS }, |
77bb000f PP |
1712 | #endif |
1713 | #ifdef SSL_OP_EPHEMERAL_RSA | |
73a46702 | 1714 | { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA }, |
77bb000f PP |
1715 | #endif |
1716 | #ifdef SSL_OP_LEGACY_SERVER_CONNECT | |
73a46702 | 1717 | { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT }, |
77bb000f PP |
1718 | #endif |
1719 | #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER | |
73a46702 | 1720 | { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER }, |
77bb000f PP |
1721 | #endif |
1722 | #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG | |
73a46702 | 1723 | { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG }, |
77bb000f PP |
1724 | #endif |
1725 | #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING | |
73a46702 | 1726 | { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING }, |
77bb000f PP |
1727 | #endif |
1728 | #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG | |
73a46702 | 1729 | { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG }, |
77bb000f PP |
1730 | #endif |
1731 | #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG | |
73a46702 | 1732 | { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG }, |
77bb000f | 1733 | #endif |
c80c5570 PP |
1734 | #ifdef SSL_OP_NO_COMPRESSION |
1735 | { US"no_compression", SSL_OP_NO_COMPRESSION }, | |
1736 | #endif | |
77bb000f | 1737 | #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION |
73a46702 | 1738 | { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION }, |
77bb000f | 1739 | #endif |
c0c7b2da PP |
1740 | #ifdef SSL_OP_NO_SSLv2 |
1741 | { US"no_sslv2", SSL_OP_NO_SSLv2 }, | |
1742 | #endif | |
1743 | #ifdef SSL_OP_NO_SSLv3 | |
1744 | { US"no_sslv3", SSL_OP_NO_SSLv3 }, | |
1745 | #endif | |
1746 | #ifdef SSL_OP_NO_TICKET | |
1747 | { US"no_ticket", SSL_OP_NO_TICKET }, | |
1748 | #endif | |
1749 | #ifdef SSL_OP_NO_TLSv1 | |
1750 | { US"no_tlsv1", SSL_OP_NO_TLSv1 }, | |
1751 | #endif | |
c80c5570 PP |
1752 | #ifdef SSL_OP_NO_TLSv1_1 |
1753 | #if SSL_OP_NO_TLSv1_1 == 0x00000400L | |
1754 | /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */ | |
1755 | #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring | |
1756 | #else | |
1757 | { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 }, | |
1758 | #endif | |
1759 | #endif | |
1760 | #ifdef SSL_OP_NO_TLSv1_2 | |
1761 | { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 }, | |
1762 | #endif | |
77bb000f | 1763 | #ifdef SSL_OP_SINGLE_DH_USE |
73a46702 | 1764 | { US"single_dh_use", SSL_OP_SINGLE_DH_USE }, |
77bb000f PP |
1765 | #endif |
1766 | #ifdef SSL_OP_SINGLE_ECDH_USE | |
73a46702 | 1767 | { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE }, |
77bb000f PP |
1768 | #endif |
1769 | #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG | |
73a46702 | 1770 | { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG }, |
77bb000f PP |
1771 | #endif |
1772 | #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG | |
73a46702 | 1773 | { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG }, |
77bb000f PP |
1774 | #endif |
1775 | #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG | |
73a46702 | 1776 | { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG }, |
77bb000f PP |
1777 | #endif |
1778 | #ifdef SSL_OP_TLS_D5_BUG | |
73a46702 | 1779 | { US"tls_d5_bug", SSL_OP_TLS_D5_BUG }, |
77bb000f PP |
1780 | #endif |
1781 | #ifdef SSL_OP_TLS_ROLLBACK_BUG | |
73a46702 | 1782 | { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG }, |
77bb000f PP |
1783 | #endif |
1784 | }; | |
1785 | static int exim_openssl_options_size = | |
1786 | sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option); | |
1787 | ||
c80c5570 | 1788 | |
77bb000f PP |
1789 | static BOOL |
1790 | tls_openssl_one_option_parse(uschar *name, long *value) | |
1791 | { | |
1792 | int first = 0; | |
1793 | int last = exim_openssl_options_size; | |
1794 | while (last > first) | |
1795 | { | |
1796 | int middle = (first + last)/2; | |
1797 | int c = Ustrcmp(name, exim_openssl_options[middle].name); | |
1798 | if (c == 0) | |
1799 | { | |
1800 | *value = exim_openssl_options[middle].value; | |
1801 | return TRUE; | |
1802 | } | |
1803 | else if (c > 0) | |
1804 | first = middle + 1; | |
1805 | else | |
1806 | last = middle; | |
1807 | } | |
1808 | return FALSE; | |
1809 | } | |
1810 | ||
1811 | ||
1812 | ||
1813 | ||
1814 | /************************************************* | |
1815 | * OpenSSL option parsing logic * | |
1816 | *************************************************/ | |
1817 | ||
1818 | /* OpenSSL has a number of compatibility options which an administrator might | |
1819 | reasonably wish to set. Interpret a list similarly to decode_bits(), so that | |
1820 | we look like log_selector. | |
1821 | ||
1822 | Arguments: | |
1823 | option_spec the administrator-supplied string of options | |
1824 | results ptr to long storage for the options bitmap | |
1825 | Returns success or failure | |
1826 | */ | |
1827 | ||
1828 | BOOL | |
1829 | tls_openssl_options_parse(uschar *option_spec, long *results) | |
1830 | { | |
1831 | long result, item; | |
1832 | uschar *s, *end; | |
1833 | uschar keep_c; | |
1834 | BOOL adding, item_parsed; | |
1835 | ||
0e944a0d | 1836 | result = 0L; |
b1770b6e | 1837 | /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed |
da3ad30d | 1838 | * from default because it increases BEAST susceptibility. */ |
77bb000f PP |
1839 | |
1840 | if (option_spec == NULL) | |
1841 | { | |
1842 | *results = result; | |
1843 | return TRUE; | |
1844 | } | |
1845 | ||
1846 | for (s=option_spec; *s != '\0'; /**/) | |
1847 | { | |
1848 | while (isspace(*s)) ++s; | |
1849 | if (*s == '\0') | |
1850 | break; | |
1851 | if (*s != '+' && *s != '-') | |
1852 | { | |
1853 | DEBUG(D_tls) debug_printf("malformed openssl option setting: " | |
0e944a0d | 1854 | "+ or - expected but found \"%s\"\n", s); |
77bb000f PP |
1855 | return FALSE; |
1856 | } | |
1857 | adding = *s++ == '+'; | |
1858 | for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ; | |
1859 | keep_c = *end; | |
1860 | *end = '\0'; | |
1861 | item_parsed = tls_openssl_one_option_parse(s, &item); | |
1862 | if (!item_parsed) | |
1863 | { | |
0e944a0d | 1864 | DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s); |
77bb000f PP |
1865 | return FALSE; |
1866 | } | |
1867 | DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n", | |
1868 | adding ? "adding" : "removing", result, item, s); | |
1869 | if (adding) | |
1870 | result |= item; | |
1871 | else | |
1872 | result &= ~item; | |
1873 | *end = keep_c; | |
1874 | s = end; | |
1875 | } | |
1876 | ||
1877 | *results = result; | |
1878 | return TRUE; | |
1879 | } | |
1880 | ||
059ec3d9 | 1881 | /* End of tls-openssl.c */ |