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; | |
35731706 | 49 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
7be682ca | 50 | static SSL_CTX *ctx_sni = NULL; |
35731706 | 51 | #endif |
059ec3d9 PH |
52 | static SSL *ssl = NULL; |
53 | ||
54 | static char ssl_errstring[256]; | |
55 | ||
56 | static int ssl_session_timeout = 200; | |
57 | static BOOL verify_optional = FALSE; | |
58 | ||
7be682ca | 59 | static BOOL reexpand_tls_files_for_sni = FALSE; |
059ec3d9 PH |
60 | |
61 | ||
7be682ca PP |
62 | typedef struct tls_ext_ctx_cb { |
63 | uschar *certificate; | |
64 | uschar *privatekey; | |
3f7eeb86 PP |
65 | #ifdef EXPERIMENTAL_OCSP |
66 | uschar *ocsp_file; | |
67 | uschar *ocsp_file_expanded; | |
68 | OCSP_RESPONSE *ocsp_response; | |
69 | #endif | |
7be682ca PP |
70 | uschar *dhparam; |
71 | /* these are cached from first expand */ | |
72 | uschar *server_cipher_list; | |
73 | /* only passed down to tls_error: */ | |
74 | host_item *host; | |
75 | } tls_ext_ctx_cb; | |
76 | ||
77 | /* should figure out a cleanup of API to handle state preserved per | |
78 | implementation, for various reasons, which can be void * in the APIs. | |
79 | For now, we hack around it. */ | |
80 | tls_ext_ctx_cb *static_cbinfo = NULL; | |
81 | ||
82 | static int | |
83 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional); | |
059ec3d9 | 84 | |
3f7eeb86 | 85 | /* Callbacks */ |
3bcbbbe2 | 86 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
3f7eeb86 | 87 | static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg); |
3bcbbbe2 | 88 | #endif |
3f7eeb86 PP |
89 | #ifdef EXPERIMENTAL_OCSP |
90 | static int tls_stapling_cb(SSL *s, void *arg); | |
91 | #endif | |
92 | ||
059ec3d9 PH |
93 | |
94 | /************************************************* | |
95 | * Handle TLS error * | |
96 | *************************************************/ | |
97 | ||
98 | /* Called from lots of places when errors occur before actually starting to do | |
99 | the TLS handshake, that is, while the session is still in clear. Always returns | |
100 | DEFER for a server and FAIL for a client so that most calls can use "return | |
101 | tls_error(...)" to do this processing and then give an appropriate return. A | |
102 | single function is used for both server and client, because it is called from | |
103 | some shared functions. | |
104 | ||
105 | Argument: | |
106 | prefix text to include in the logged error | |
107 | host NULL if setting up a server; | |
108 | the connected host if setting up a client | |
7199e1ee | 109 | msg error message or NULL if we should ask OpenSSL |
059ec3d9 PH |
110 | |
111 | Returns: OK/DEFER/FAIL | |
112 | */ | |
113 | ||
114 | static int | |
7199e1ee | 115 | tls_error(uschar *prefix, host_item *host, uschar *msg) |
059ec3d9 | 116 | { |
7199e1ee TF |
117 | if (msg == NULL) |
118 | { | |
119 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
5ca6d115 | 120 | msg = (uschar *)ssl_errstring; |
7199e1ee TF |
121 | } |
122 | ||
059ec3d9 PH |
123 | if (host == NULL) |
124 | { | |
7199e1ee | 125 | uschar *conn_info = smtp_get_connection_info(); |
5ca6d115 | 126 | if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) |
7199e1ee TF |
127 | conn_info += 5; |
128 | log_write(0, LOG_MAIN, "TLS error on %s (%s): %s", | |
129 | conn_info, prefix, msg); | |
059ec3d9 PH |
130 | return DEFER; |
131 | } | |
132 | else | |
133 | { | |
134 | log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s): %s", | |
7199e1ee | 135 | host->name, host->address, prefix, msg); |
059ec3d9 PH |
136 | return FAIL; |
137 | } | |
138 | } | |
139 | ||
140 | ||
141 | ||
142 | /************************************************* | |
143 | * Callback to generate RSA key * | |
144 | *************************************************/ | |
145 | ||
146 | /* | |
147 | Arguments: | |
148 | s SSL connection | |
149 | export not used | |
150 | keylength keylength | |
151 | ||
152 | Returns: pointer to generated key | |
153 | */ | |
154 | ||
155 | static RSA * | |
156 | rsa_callback(SSL *s, int export, int keylength) | |
157 | { | |
158 | RSA *rsa_key; | |
159 | export = export; /* Shut picky compilers up */ | |
160 | DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength); | |
161 | rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL); | |
162 | if (rsa_key == NULL) | |
163 | { | |
164 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
165 | log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s", | |
166 | ssl_errstring); | |
167 | return NULL; | |
168 | } | |
169 | return rsa_key; | |
170 | } | |
171 | ||
172 | ||
173 | ||
174 | ||
175 | /************************************************* | |
176 | * Callback for verification * | |
177 | *************************************************/ | |
178 | ||
179 | /* The SSL library does certificate verification if set up to do so. This | |
180 | callback has the current yes/no state is in "state". If verification succeeded, | |
181 | we set up the tls_peerdn string. If verification failed, what happens depends | |
182 | on whether the client is required to present a verifiable certificate or not. | |
183 | ||
184 | If verification is optional, we change the state to yes, but still log the | |
185 | verification error. For some reason (it really would help to have proper | |
186 | documentation of OpenSSL), this callback function then gets called again, this | |
187 | time with state = 1. In fact, that's useful, because we can set up the peerdn | |
188 | value, but we must take care not to set the private verified flag on the second | |
189 | time through. | |
190 | ||
191 | Note: this function is not called if the client fails to present a certificate | |
192 | when asked. We get here only if a certificate has been received. Handling of | |
193 | optional verification for this case is done when requesting SSL to verify, by | |
194 | setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case. | |
195 | ||
196 | Arguments: | |
197 | state current yes/no state as 1/0 | |
198 | x509ctx certificate information. | |
199 | ||
200 | Returns: 1 if verified, 0 if not | |
201 | */ | |
202 | ||
203 | static int | |
204 | verify_callback(int state, X509_STORE_CTX *x509ctx) | |
205 | { | |
206 | static uschar txt[256]; | |
207 | ||
208 | X509_NAME_oneline(X509_get_subject_name(x509ctx->current_cert), | |
209 | CS txt, sizeof(txt)); | |
210 | ||
211 | if (state == 0) | |
212 | { | |
213 | log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s", | |
214 | x509ctx->error_depth, | |
215 | X509_verify_cert_error_string(x509ctx->error), | |
216 | txt); | |
217 | tls_certificate_verified = FALSE; | |
218 | verify_callback_called = TRUE; | |
219 | if (!verify_optional) return 0; /* reject */ | |
220 | DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in " | |
221 | "tls_try_verify_hosts)\n"); | |
222 | return 1; /* accept */ | |
223 | } | |
224 | ||
225 | if (x509ctx->error_depth != 0) | |
226 | { | |
227 | DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d cert=%s\n", | |
228 | x509ctx->error_depth, txt); | |
229 | } | |
230 | else | |
231 | { | |
232 | DEBUG(D_tls) debug_printf("SSL%s peer: %s\n", | |
233 | verify_callback_called? "" : " authenticated", txt); | |
234 | tls_peerdn = txt; | |
235 | } | |
236 | ||
059ec3d9 PH |
237 | if (!verify_callback_called) tls_certificate_verified = TRUE; |
238 | verify_callback_called = TRUE; | |
239 | ||
240 | return 1; /* accept */ | |
241 | } | |
242 | ||
243 | ||
244 | ||
245 | /************************************************* | |
246 | * Information callback * | |
247 | *************************************************/ | |
248 | ||
249 | /* The SSL library functions call this from time to time to indicate what they | |
7be682ca PP |
250 | are doing. We copy the string to the debugging output when TLS debugging has |
251 | been requested. | |
059ec3d9 PH |
252 | |
253 | Arguments: | |
254 | s the SSL connection | |
255 | where | |
256 | ret | |
257 | ||
258 | Returns: nothing | |
259 | */ | |
260 | ||
261 | static void | |
262 | info_callback(SSL *s, int where, int ret) | |
263 | { | |
264 | where = where; | |
265 | ret = ret; | |
266 | DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s)); | |
267 | } | |
268 | ||
269 | ||
270 | ||
271 | /************************************************* | |
272 | * Initialize for DH * | |
273 | *************************************************/ | |
274 | ||
275 | /* If dhparam is set, expand it, and load up the parameters for DH encryption. | |
276 | ||
277 | Arguments: | |
278 | dhparam DH parameter file | |
7199e1ee | 279 | host connected host, if client; NULL if server |
059ec3d9 PH |
280 | |
281 | Returns: TRUE if OK (nothing to set up, or setup worked) | |
282 | */ | |
283 | ||
284 | static BOOL | |
7199e1ee | 285 | init_dh(uschar *dhparam, host_item *host) |
059ec3d9 PH |
286 | { |
287 | BOOL yield = TRUE; | |
288 | BIO *bio; | |
289 | DH *dh; | |
290 | uschar *dhexpanded; | |
291 | ||
292 | if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded)) | |
293 | return FALSE; | |
294 | ||
295 | if (dhexpanded == NULL) return TRUE; | |
296 | ||
297 | if ((bio = BIO_new_file(CS dhexpanded, "r")) == NULL) | |
298 | { | |
7199e1ee | 299 | tls_error(string_sprintf("could not read dhparams file %s", dhexpanded), |
5ca6d115 | 300 | host, (uschar *)strerror(errno)); |
059ec3d9 PH |
301 | yield = FALSE; |
302 | } | |
303 | else | |
304 | { | |
305 | if ((dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)) == NULL) | |
306 | { | |
7199e1ee TF |
307 | tls_error(string_sprintf("could not read dhparams file %s", dhexpanded), |
308 | host, NULL); | |
059ec3d9 PH |
309 | yield = FALSE; |
310 | } | |
311 | else | |
312 | { | |
3375e053 PP |
313 | if ((8*DH_size(dh)) > tls_dh_max_bits) |
314 | { | |
315 | DEBUG(D_tls) | |
316 | debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d", | |
317 | 8*DH_size(dh), tls_dh_max_bits); | |
318 | } | |
319 | else | |
320 | { | |
321 | SSL_CTX_set_tmp_dh(ctx, dh); | |
322 | DEBUG(D_tls) | |
323 | debug_printf("Diffie-Hellman initialized from %s with %d-bit key\n", | |
324 | dhexpanded, 8*DH_size(dh)); | |
325 | } | |
059ec3d9 PH |
326 | DH_free(dh); |
327 | } | |
328 | BIO_free(bio); | |
329 | } | |
330 | ||
331 | return yield; | |
332 | } | |
333 | ||
334 | ||
335 | ||
336 | ||
3f7eeb86 PP |
337 | #ifdef EXPERIMENTAL_OCSP |
338 | /************************************************* | |
339 | * Load OCSP information into state * | |
340 | *************************************************/ | |
341 | ||
342 | /* Called to load the OCSP response from the given file into memory, once | |
343 | caller has determined this is needed. Checks validity. Debugs a message | |
344 | if invalid. | |
345 | ||
346 | ASSUMES: single response, for single cert. | |
347 | ||
348 | Arguments: | |
349 | sctx the SSL_CTX* to update | |
350 | cbinfo various parts of session state | |
351 | expanded the filename putatively holding an OCSP response | |
352 | ||
353 | */ | |
354 | ||
355 | static void | |
356 | ocsp_load_response(SSL_CTX *sctx, | |
357 | tls_ext_ctx_cb *cbinfo, | |
358 | const uschar *expanded) | |
359 | { | |
360 | BIO *bio; | |
361 | OCSP_RESPONSE *resp; | |
362 | OCSP_BASICRESP *basic_response; | |
363 | OCSP_SINGLERESP *single_response; | |
364 | ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd; | |
365 | X509_STORE *store; | |
366 | unsigned long verify_flags; | |
367 | int status, reason, i; | |
368 | ||
369 | cbinfo->ocsp_file_expanded = string_copy(expanded); | |
370 | if (cbinfo->ocsp_response) | |
371 | { | |
372 | OCSP_RESPONSE_free(cbinfo->ocsp_response); | |
373 | cbinfo->ocsp_response = NULL; | |
374 | } | |
375 | ||
376 | bio = BIO_new_file(CS cbinfo->ocsp_file_expanded, "rb"); | |
377 | if (!bio) | |
378 | { | |
379 | DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n", | |
380 | cbinfo->ocsp_file_expanded); | |
381 | return; | |
382 | } | |
383 | ||
384 | resp = d2i_OCSP_RESPONSE_bio(bio, NULL); | |
385 | BIO_free(bio); | |
386 | if (!resp) | |
387 | { | |
388 | DEBUG(D_tls) debug_printf("Error reading OCSP response.\n"); | |
389 | return; | |
390 | } | |
391 | ||
392 | status = OCSP_response_status(resp); | |
393 | if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL) | |
394 | { | |
395 | DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n", | |
396 | OCSP_response_status_str(status), status); | |
397 | return; | |
398 | } | |
399 | ||
400 | basic_response = OCSP_response_get1_basic(resp); | |
401 | if (!basic_response) | |
402 | { | |
403 | DEBUG(D_tls) | |
404 | debug_printf("OCSP response parse error: unable to extract basic response.\n"); | |
405 | return; | |
406 | } | |
407 | ||
408 | store = SSL_CTX_get_cert_store(sctx); | |
409 | verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */ | |
410 | ||
411 | /* May need to expose ability to adjust those flags? | |
412 | OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT | |
413 | OCSP_TRUSTOTHER OCSP_NOINTERN */ | |
414 | ||
415 | i = OCSP_basic_verify(basic_response, NULL, store, verify_flags); | |
416 | if (i <= 0) | |
417 | { | |
418 | DEBUG(D_tls) { | |
419 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
420 | debug_printf("OCSP response verify failure: %s\n", US ssl_errstring); | |
421 | } | |
422 | return; | |
423 | } | |
424 | ||
425 | /* Here's the simplifying assumption: there's only one response, for the | |
426 | one certificate we use, and nothing for anything else in a chain. If this | |
427 | proves false, we need to extract a cert id from our issued cert | |
428 | (tls_certificate) and use that for OCSP_resp_find_status() (which finds the | |
429 | right cert in the stack and then calls OCSP_single_get0_status()). | |
430 | ||
431 | I'm hoping to avoid reworking a bunch more of how we handle state here. */ | |
432 | single_response = OCSP_resp_get0(basic_response, 0); | |
433 | if (!single_response) | |
434 | { | |
435 | DEBUG(D_tls) | |
436 | debug_printf("Unable to get first response from OCSP basic response.\n"); | |
437 | return; | |
438 | } | |
439 | ||
440 | status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd); | |
441 | /* how does this status differ from the one above? */ | |
442 | if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL) | |
443 | { | |
444 | DEBUG(D_tls) debug_printf("OCSP response not valid (take 2): %s (%d)\n", | |
445 | OCSP_response_status_str(status), status); | |
446 | return; | |
447 | } | |
448 | ||
449 | if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE)) | |
450 | { | |
451 | DEBUG(D_tls) debug_printf("OCSP status invalid times.\n"); | |
452 | return; | |
453 | } | |
454 | ||
455 | cbinfo->ocsp_response = resp; | |
456 | } | |
457 | #endif | |
458 | ||
459 | ||
460 | ||
461 | ||
7be682ca PP |
462 | /************************************************* |
463 | * Expand key and cert file specs * | |
464 | *************************************************/ | |
465 | ||
466 | /* Called once during tls_init and possibly againt during TLS setup, for a | |
467 | new context, if Server Name Indication was used and tls_sni was seen in | |
468 | the certificate string. | |
469 | ||
470 | Arguments: | |
471 | sctx the SSL_CTX* to update | |
472 | cbinfo various parts of session state | |
473 | ||
474 | Returns: OK/DEFER/FAIL | |
475 | */ | |
476 | ||
477 | static int | |
3f7eeb86 | 478 | tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo) |
7be682ca PP |
479 | { |
480 | uschar *expanded; | |
481 | ||
482 | if (cbinfo->certificate == NULL) | |
483 | return OK; | |
484 | ||
485 | if (Ustrstr(cbinfo->certificate, US"tls_sni")) | |
486 | reexpand_tls_files_for_sni = TRUE; | |
487 | ||
488 | if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded)) | |
489 | return DEFER; | |
490 | ||
491 | if (expanded != NULL) | |
492 | { | |
493 | DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded); | |
494 | if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded)) | |
495 | return tls_error(string_sprintf( | |
496 | "SSL_CTX_use_certificate_chain_file file=%s", expanded), | |
497 | cbinfo->host, NULL); | |
498 | } | |
499 | ||
500 | if (cbinfo->privatekey != NULL && | |
501 | !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded)) | |
502 | return DEFER; | |
503 | ||
504 | /* If expansion was forced to fail, key_expanded will be NULL. If the result | |
505 | of the expansion is an empty string, ignore it also, and assume the private | |
506 | key is in the same file as the certificate. */ | |
507 | ||
508 | if (expanded != NULL && *expanded != 0) | |
509 | { | |
510 | DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded); | |
511 | if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM)) | |
512 | return tls_error(string_sprintf( | |
513 | "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL); | |
514 | } | |
515 | ||
3f7eeb86 PP |
516 | #ifdef EXPERIMENTAL_OCSP |
517 | if (cbinfo->ocsp_file != NULL) | |
518 | { | |
519 | if (!expand_check(cbinfo->ocsp_file, US"tls_ocsp_file", &expanded)) | |
520 | return DEFER; | |
521 | ||
522 | if (expanded != NULL && *expanded != 0) | |
523 | { | |
524 | DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded); | |
525 | if (cbinfo->ocsp_file_expanded && | |
526 | (Ustrcmp(expanded, cbinfo->ocsp_file_expanded) == 0)) | |
527 | { | |
528 | DEBUG(D_tls) | |
529 | debug_printf("tls_ocsp_file value unchanged, using existing values.\n"); | |
530 | } else { | |
531 | ocsp_load_response(sctx, cbinfo, expanded); | |
532 | } | |
533 | } | |
534 | } | |
535 | #endif | |
536 | ||
7be682ca PP |
537 | return OK; |
538 | } | |
539 | ||
540 | ||
541 | ||
542 | ||
543 | /************************************************* | |
544 | * Callback to handle SNI * | |
545 | *************************************************/ | |
546 | ||
547 | /* Called when acting as server during the TLS session setup if a Server Name | |
548 | Indication extension was sent by the client. | |
549 | ||
550 | API documentation is OpenSSL s_server.c implementation. | |
551 | ||
552 | Arguments: | |
553 | s SSL* of the current session | |
554 | ad unknown (part of OpenSSL API) (unused) | |
555 | arg Callback of "our" registered data | |
556 | ||
557 | Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK} | |
558 | */ | |
559 | ||
3bcbbbe2 | 560 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
7be682ca PP |
561 | static int |
562 | tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg) | |
563 | { | |
564 | const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name); | |
3f7eeb86 | 565 | tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg; |
7be682ca | 566 | int rc; |
3f0945ff | 567 | int old_pool = store_pool; |
7be682ca PP |
568 | |
569 | if (!servername) | |
570 | return SSL_TLSEXT_ERR_OK; | |
571 | ||
3f0945ff | 572 | DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername, |
7be682ca PP |
573 | reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)"); |
574 | ||
575 | /* Make the extension value available for expansion */ | |
3f0945ff PP |
576 | store_pool = POOL_PERM; |
577 | tls_sni = string_copy(US servername); | |
578 | store_pool = old_pool; | |
7be682ca PP |
579 | |
580 | if (!reexpand_tls_files_for_sni) | |
581 | return SSL_TLSEXT_ERR_OK; | |
582 | ||
583 | /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually; | |
584 | not confident that memcpy wouldn't break some internal reference counting. | |
585 | Especially since there's a references struct member, which would be off. */ | |
586 | ||
587 | ctx_sni = SSL_CTX_new(SSLv23_server_method()); | |
588 | if (!ctx_sni) | |
589 | { | |
590 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
591 | DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring); | |
592 | return SSL_TLSEXT_ERR_NOACK; | |
593 | } | |
594 | ||
595 | /* Not sure how many of these are actually needed, since SSL object | |
596 | already exists. Might even need this selfsame callback, for reneg? */ | |
597 | ||
598 | SSL_CTX_set_info_callback(ctx_sni, SSL_CTX_get_info_callback(ctx)); | |
599 | SSL_CTX_set_mode(ctx_sni, SSL_CTX_get_mode(ctx)); | |
600 | SSL_CTX_set_options(ctx_sni, SSL_CTX_get_options(ctx)); | |
601 | SSL_CTX_set_timeout(ctx_sni, SSL_CTX_get_timeout(ctx)); | |
602 | SSL_CTX_set_tlsext_servername_callback(ctx_sni, tls_servername_cb); | |
603 | SSL_CTX_set_tlsext_servername_arg(ctx_sni, cbinfo); | |
604 | if (cbinfo->server_cipher_list) | |
605 | SSL_CTX_set_cipher_list(ctx_sni, CS cbinfo->server_cipher_list); | |
3f7eeb86 PP |
606 | #ifdef EXPERIMENTAL_OCSP |
607 | if (cbinfo->ocsp_file) | |
608 | { | |
609 | SSL_CTX_set_tlsext_status_cb(ctx_sni, tls_stapling_cb); | |
610 | SSL_CTX_set_tlsext_status_arg(ctx, cbinfo); | |
611 | } | |
612 | #endif | |
7be682ca | 613 | |
3f7eeb86 | 614 | rc = setup_certs(ctx_sni, tls_verify_certificates, tls_crl, NULL, FALSE); |
7be682ca PP |
615 | if (rc != OK) return SSL_TLSEXT_ERR_NOACK; |
616 | ||
3f7eeb86 PP |
617 | /* do this after setup_certs, because this can require the certs for verifying |
618 | OCSP information. */ | |
619 | rc = tls_expand_session_files(ctx_sni, cbinfo); | |
7be682ca PP |
620 | if (rc != OK) return SSL_TLSEXT_ERR_NOACK; |
621 | ||
622 | DEBUG(D_tls) debug_printf("Switching SSL context.\n"); | |
623 | SSL_set_SSL_CTX(s, ctx_sni); | |
624 | ||
625 | return SSL_TLSEXT_ERR_OK; | |
626 | } | |
3bcbbbe2 | 627 | #endif /* EXIM_HAVE_OPENSSL_TLSEXT */ |
7be682ca PP |
628 | |
629 | ||
630 | ||
631 | ||
3f7eeb86 PP |
632 | #ifdef EXPERIMENTAL_OCSP |
633 | /************************************************* | |
634 | * Callback to handle OCSP Stapling * | |
635 | *************************************************/ | |
636 | ||
637 | /* Called when acting as server during the TLS session setup if the client | |
638 | requests OCSP information with a Certificate Status Request. | |
639 | ||
640 | Documentation via openssl s_server.c and the Apache patch from the OpenSSL | |
641 | project. | |
642 | ||
643 | */ | |
644 | ||
645 | static int | |
646 | tls_stapling_cb(SSL *s, void *arg) | |
647 | { | |
648 | const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg; | |
649 | uschar *response_der; | |
650 | int response_der_len; | |
651 | ||
652 | DEBUG(D_tls) debug_printf("Received TLS status request (OCSP stapling); %s response.\n", | |
653 | cbinfo->ocsp_response ? "have" : "lack"); | |
654 | if (!cbinfo->ocsp_response) | |
655 | return SSL_TLSEXT_ERR_NOACK; | |
656 | ||
657 | response_der = NULL; | |
658 | response_der_len = i2d_OCSP_RESPONSE(cbinfo->ocsp_response, &response_der); | |
659 | if (response_der_len <= 0) | |
660 | return SSL_TLSEXT_ERR_NOACK; | |
661 | ||
662 | SSL_set_tlsext_status_ocsp_resp(ssl, response_der, response_der_len); | |
663 | return SSL_TLSEXT_ERR_OK; | |
664 | } | |
665 | ||
666 | #endif /* EXPERIMENTAL_OCSP */ | |
667 | ||
668 | ||
669 | ||
670 | ||
059ec3d9 PH |
671 | /************************************************* |
672 | * Initialize for TLS * | |
673 | *************************************************/ | |
674 | ||
675 | /* Called from both server and client code, to do preliminary initialization of | |
676 | the library. | |
677 | ||
678 | Arguments: | |
679 | host connected host, if client; NULL if server | |
680 | dhparam DH parameter file | |
681 | certificate certificate file | |
682 | privatekey private key | |
683 | addr address if client; NULL if server (for some randomness) | |
684 | ||
685 | Returns: OK/DEFER/FAIL | |
686 | */ | |
687 | ||
688 | static int | |
c91535f3 | 689 | tls_init(host_item *host, uschar *dhparam, uschar *certificate, |
3f7eeb86 PP |
690 | uschar *privatekey, |
691 | #ifdef EXPERIMENTAL_OCSP | |
692 | uschar *ocsp_file, | |
693 | #endif | |
694 | address_item *addr) | |
059ec3d9 | 695 | { |
77bb000f | 696 | long init_options; |
7be682ca | 697 | int rc; |
77bb000f | 698 | BOOL okay; |
7be682ca PP |
699 | tls_ext_ctx_cb *cbinfo; |
700 | ||
701 | cbinfo = store_malloc(sizeof(tls_ext_ctx_cb)); | |
702 | cbinfo->certificate = certificate; | |
703 | cbinfo->privatekey = privatekey; | |
3f7eeb86 PP |
704 | #ifdef EXPERIMENTAL_OCSP |
705 | cbinfo->ocsp_file = ocsp_file; | |
706 | #endif | |
7be682ca PP |
707 | cbinfo->dhparam = dhparam; |
708 | cbinfo->host = host; | |
77bb000f | 709 | |
059ec3d9 PH |
710 | SSL_load_error_strings(); /* basic set up */ |
711 | OpenSSL_add_ssl_algorithms(); | |
712 | ||
388d6564 | 713 | #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256) |
77bb000f | 714 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the |
a0475b69 TK |
715 | list of available digests. */ |
716 | EVP_add_digest(EVP_sha256()); | |
cf1ef1a9 | 717 | #endif |
a0475b69 | 718 | |
059ec3d9 PH |
719 | /* Create a context */ |
720 | ||
721 | ctx = SSL_CTX_new((host == NULL)? | |
722 | SSLv23_server_method() : SSLv23_client_method()); | |
723 | ||
7199e1ee | 724 | if (ctx == NULL) return tls_error(US"SSL_CTX_new", host, NULL); |
059ec3d9 PH |
725 | |
726 | /* It turns out that we need to seed the random number generator this early in | |
727 | order to get the full complement of ciphers to work. It took me roughly a day | |
728 | of work to discover this by experiment. | |
729 | ||
730 | On systems that have /dev/urandom, SSL may automatically seed itself from | |
731 | there. Otherwise, we have to make something up as best we can. Double check | |
732 | afterwards. */ | |
733 | ||
734 | if (!RAND_status()) | |
735 | { | |
736 | randstuff r; | |
9e3331ea | 737 | gettimeofday(&r.tv, NULL); |
059ec3d9 PH |
738 | r.p = getpid(); |
739 | ||
740 | RAND_seed((uschar *)(&r), sizeof(r)); | |
741 | RAND_seed((uschar *)big_buffer, big_buffer_size); | |
742 | if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr)); | |
743 | ||
744 | if (!RAND_status()) | |
7199e1ee | 745 | return tls_error(US"RAND_status", host, |
5ca6d115 | 746 | US"unable to seed random number generator"); |
059ec3d9 PH |
747 | } |
748 | ||
749 | /* Set up the information callback, which outputs if debugging is at a suitable | |
750 | level. */ | |
751 | ||
58c01c94 | 752 | SSL_CTX_set_info_callback(ctx, (void (*)())info_callback); |
059ec3d9 | 753 | |
c80c5570 PP |
754 | /* Automatically re-try reads/writes after renegotiation. */ |
755 | (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY); | |
756 | ||
77bb000f PP |
757 | /* Apply administrator-supplied work-arounds. |
758 | Historically we applied just one requested option, | |
759 | SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we | |
760 | moved to an administrator-controlled list of options to specify and | |
761 | grandfathered in the first one as the default value for "openssl_options". | |
059ec3d9 | 762 | |
77bb000f PP |
763 | No OpenSSL version number checks: the options we accept depend upon the |
764 | availability of the option value macros from OpenSSL. */ | |
059ec3d9 | 765 | |
77bb000f PP |
766 | okay = tls_openssl_options_parse(openssl_options, &init_options); |
767 | if (!okay) | |
73a46702 | 768 | return tls_error(US"openssl_options parsing failed", host, NULL); |
77bb000f PP |
769 | |
770 | if (init_options) | |
771 | { | |
772 | DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options); | |
773 | if (!(SSL_CTX_set_options(ctx, init_options))) | |
774 | return tls_error(string_sprintf( | |
775 | "SSL_CTX_set_option(%#lx)", init_options), host, NULL); | |
776 | } | |
777 | else | |
778 | DEBUG(D_tls) debug_printf("no SSL CTX options to set\n"); | |
059ec3d9 PH |
779 | |
780 | /* Initialize with DH parameters if supplied */ | |
781 | ||
7199e1ee | 782 | if (!init_dh(dhparam, host)) return DEFER; |
059ec3d9 | 783 | |
3f7eeb86 | 784 | /* Set up certificate and key (and perhaps OCSP info) */ |
059ec3d9 | 785 | |
7be682ca PP |
786 | rc = tls_expand_session_files(ctx, cbinfo); |
787 | if (rc != OK) return rc; | |
c91535f3 | 788 | |
7be682ca | 789 | /* If we need to handle SNI, do so */ |
3bcbbbe2 | 790 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
3f0945ff PP |
791 | if (host == NULL) |
792 | { | |
3f7eeb86 PP |
793 | #ifdef EXPERIMENTAL_OCSP |
794 | /* We check ocsp_file, not ocsp_response, because we care about if | |
795 | the option exists, not what the current expansion might be, as SNI might | |
796 | change the certificate and OCSP file in use between now and the time the | |
797 | callback is invoked. */ | |
798 | if (cbinfo->ocsp_file) | |
799 | { | |
800 | SSL_CTX_set_tlsext_status_cb(ctx, tls_stapling_cb); | |
801 | SSL_CTX_set_tlsext_status_arg(ctx, cbinfo); | |
802 | } | |
803 | #endif | |
3f0945ff PP |
804 | /* We always do this, so that $tls_sni is available even if not used in |
805 | tls_certificate */ | |
806 | SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb); | |
807 | SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo); | |
808 | } | |
7be682ca | 809 | #endif |
059ec3d9 PH |
810 | |
811 | /* Set up the RSA callback */ | |
812 | ||
813 | SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback); | |
814 | ||
815 | /* Finally, set the timeout, and we are done */ | |
816 | ||
817 | SSL_CTX_set_timeout(ctx, ssl_session_timeout); | |
818 | DEBUG(D_tls) debug_printf("Initialized TLS\n"); | |
7be682ca PP |
819 | |
820 | static_cbinfo = cbinfo; | |
821 | ||
059ec3d9 PH |
822 | return OK; |
823 | } | |
824 | ||
825 | ||
826 | ||
827 | ||
828 | /************************************************* | |
829 | * Get name of cipher in use * | |
830 | *************************************************/ | |
831 | ||
832 | /* The answer is left in a static buffer, and tls_cipher is set to point | |
833 | to it. | |
834 | ||
835 | Argument: pointer to an SSL structure for the connection | |
836 | Returns: nothing | |
837 | */ | |
838 | ||
839 | static void | |
840 | construct_cipher_name(SSL *ssl) | |
841 | { | |
842 | static uschar cipherbuf[256]; | |
57b3a7f5 PP |
843 | /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't |
844 | yet reflect that. It should be a safe change anyway, even 0.9.8 versions have | |
845 | the accessor functions use const in the prototype. */ | |
846 | const SSL_CIPHER *c; | |
059ec3d9 | 847 | uschar *ver; |
059ec3d9 PH |
848 | |
849 | switch (ssl->session->ssl_version) | |
850 | { | |
851 | case SSL2_VERSION: | |
852 | ver = US"SSLv2"; | |
853 | break; | |
854 | ||
855 | case SSL3_VERSION: | |
856 | ver = US"SSLv3"; | |
857 | break; | |
858 | ||
859 | case TLS1_VERSION: | |
860 | ver = US"TLSv1"; | |
861 | break; | |
862 | ||
c80c5570 PP |
863 | #ifdef TLS1_1_VERSION |
864 | case TLS1_1_VERSION: | |
865 | ver = US"TLSv1.1"; | |
866 | break; | |
867 | #endif | |
868 | ||
869 | #ifdef TLS1_2_VERSION | |
870 | case TLS1_2_VERSION: | |
871 | ver = US"TLSv1.2"; | |
872 | break; | |
873 | #endif | |
874 | ||
059ec3d9 PH |
875 | default: |
876 | ver = US"UNKNOWN"; | |
877 | } | |
878 | ||
57b3a7f5 | 879 | c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl); |
edc33b5f | 880 | SSL_CIPHER_get_bits(c, &tls_bits); |
059ec3d9 PH |
881 | |
882 | string_format(cipherbuf, sizeof(cipherbuf), "%s:%s:%u", ver, | |
edc33b5f | 883 | SSL_CIPHER_get_name(c), tls_bits); |
059ec3d9 PH |
884 | tls_cipher = cipherbuf; |
885 | ||
886 | DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf); | |
887 | } | |
888 | ||
889 | ||
890 | ||
891 | ||
892 | ||
893 | /************************************************* | |
894 | * Set up for verifying certificates * | |
895 | *************************************************/ | |
896 | ||
897 | /* Called by both client and server startup | |
898 | ||
899 | Arguments: | |
7be682ca | 900 | sctx SSL_CTX* to initialise |
059ec3d9 PH |
901 | certs certs file or NULL |
902 | crl CRL file or NULL | |
903 | host NULL in a server; the remote host in a client | |
904 | optional TRUE if called from a server for a host in tls_try_verify_hosts; | |
905 | otherwise passed as FALSE | |
906 | ||
907 | Returns: OK/DEFER/FAIL | |
908 | */ | |
909 | ||
910 | static int | |
7be682ca | 911 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional) |
059ec3d9 PH |
912 | { |
913 | uschar *expcerts, *expcrl; | |
914 | ||
915 | if (!expand_check(certs, US"tls_verify_certificates", &expcerts)) | |
916 | return DEFER; | |
917 | ||
918 | if (expcerts != NULL) | |
919 | { | |
920 | struct stat statbuf; | |
7be682ca | 921 | if (!SSL_CTX_set_default_verify_paths(sctx)) |
7199e1ee | 922 | return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL); |
059ec3d9 PH |
923 | |
924 | if (Ustat(expcerts, &statbuf) < 0) | |
925 | { | |
926 | log_write(0, LOG_MAIN|LOG_PANIC, | |
927 | "failed to stat %s for certificates", expcerts); | |
928 | return DEFER; | |
929 | } | |
930 | else | |
931 | { | |
932 | uschar *file, *dir; | |
933 | if ((statbuf.st_mode & S_IFMT) == S_IFDIR) | |
934 | { file = NULL; dir = expcerts; } | |
935 | else | |
936 | { file = expcerts; dir = NULL; } | |
937 | ||
938 | /* If a certificate file is empty, the next function fails with an | |
939 | unhelpful error message. If we skip it, we get the correct behaviour (no | |
940 | certificates are recognized, but the error message is still misleading (it | |
941 | says no certificate was supplied.) But this is better. */ | |
942 | ||
943 | if ((file == NULL || statbuf.st_size > 0) && | |
7be682ca | 944 | !SSL_CTX_load_verify_locations(sctx, CS file, CS dir)) |
7199e1ee | 945 | return tls_error(US"SSL_CTX_load_verify_locations", host, NULL); |
059ec3d9 PH |
946 | |
947 | if (file != NULL) | |
948 | { | |
7be682ca | 949 | SSL_CTX_set_client_CA_list(sctx, SSL_load_client_CA_file(CS file)); |
059ec3d9 PH |
950 | } |
951 | } | |
952 | ||
953 | /* Handle a certificate revocation list. */ | |
954 | ||
955 | #if OPENSSL_VERSION_NUMBER > 0x00907000L | |
956 | ||
8b417f2c PH |
957 | /* This bit of code is now the version supplied by Lars Mainka. (I have |
958 | * merely reformatted it into the Exim code style.) | |
959 | ||
960 | * "From here I changed the code to add support for multiple crl's | |
961 | * in pem format in one file or to support hashed directory entries in | |
962 | * pem format instead of a file. This method now uses the library function | |
963 | * X509_STORE_load_locations to add the CRL location to the SSL context. | |
964 | * OpenSSL will then handle the verify against CA certs and CRLs by | |
965 | * itself in the verify callback." */ | |
966 | ||
059ec3d9 PH |
967 | if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER; |
968 | if (expcrl != NULL && *expcrl != 0) | |
969 | { | |
8b417f2c PH |
970 | struct stat statbufcrl; |
971 | if (Ustat(expcrl, &statbufcrl) < 0) | |
972 | { | |
973 | log_write(0, LOG_MAIN|LOG_PANIC, | |
974 | "failed to stat %s for certificates revocation lists", expcrl); | |
975 | return DEFER; | |
976 | } | |
977 | else | |
059ec3d9 | 978 | { |
8b417f2c PH |
979 | /* is it a file or directory? */ |
980 | uschar *file, *dir; | |
7be682ca | 981 | X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx); |
8b417f2c | 982 | if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR) |
059ec3d9 | 983 | { |
8b417f2c PH |
984 | file = NULL; |
985 | dir = expcrl; | |
986 | DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir); | |
059ec3d9 PH |
987 | } |
988 | else | |
989 | { | |
8b417f2c PH |
990 | file = expcrl; |
991 | dir = NULL; | |
992 | DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file); | |
059ec3d9 | 993 | } |
8b417f2c | 994 | if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0) |
7199e1ee | 995 | return tls_error(US"X509_STORE_load_locations", host, NULL); |
8b417f2c PH |
996 | |
997 | /* setting the flags to check against the complete crl chain */ | |
998 | ||
999 | X509_STORE_set_flags(cvstore, | |
1000 | X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL); | |
059ec3d9 | 1001 | } |
059ec3d9 PH |
1002 | } |
1003 | ||
1004 | #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */ | |
1005 | ||
1006 | /* If verification is optional, don't fail if no certificate */ | |
1007 | ||
7be682ca | 1008 | SSL_CTX_set_verify(sctx, |
059ec3d9 PH |
1009 | SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT), |
1010 | verify_callback); | |
1011 | } | |
1012 | ||
1013 | return OK; | |
1014 | } | |
1015 | ||
1016 | ||
1017 | ||
1018 | /************************************************* | |
1019 | * Start a TLS session in a server * | |
1020 | *************************************************/ | |
1021 | ||
1022 | /* This is called when Exim is running as a server, after having received | |
1023 | the STARTTLS command. It must respond to that command, and then negotiate | |
1024 | a TLS session. | |
1025 | ||
1026 | Arguments: | |
1027 | require_ciphers allowed ciphers | |
1028 | ||
1029 | Returns: OK on success | |
1030 | DEFER for errors before the start of the negotiation | |
1031 | FAIL for errors during the negotation; the server can't | |
1032 | continue running. | |
1033 | */ | |
1034 | ||
1035 | int | |
17c76198 | 1036 | tls_server_start(const uschar *require_ciphers) |
059ec3d9 PH |
1037 | { |
1038 | int rc; | |
1039 | uschar *expciphers; | |
7be682ca | 1040 | tls_ext_ctx_cb *cbinfo; |
059ec3d9 PH |
1041 | |
1042 | /* Check for previous activation */ | |
1043 | ||
1044 | if (tls_active >= 0) | |
1045 | { | |
5ca6d115 | 1046 | tls_error(US"STARTTLS received after TLS started", NULL, US""); |
059ec3d9 PH |
1047 | smtp_printf("554 Already in TLS\r\n"); |
1048 | return FAIL; | |
1049 | } | |
1050 | ||
1051 | /* Initialize the SSL library. If it fails, it will already have logged | |
1052 | the error. */ | |
1053 | ||
3f7eeb86 PP |
1054 | rc = tls_init(NULL, tls_dhparam, tls_certificate, tls_privatekey, |
1055 | #ifdef EXPERIMENTAL_OCSP | |
1056 | tls_ocsp_file, | |
1057 | #endif | |
1058 | NULL); | |
059ec3d9 | 1059 | if (rc != OK) return rc; |
7be682ca | 1060 | cbinfo = static_cbinfo; |
059ec3d9 PH |
1061 | |
1062 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers)) | |
1063 | return FAIL; | |
1064 | ||
1065 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they | |
17c76198 PP |
1066 | were historically separated by underscores. So that I can use either form in my |
1067 | tests, and also for general convenience, we turn underscores into hyphens here. | |
1068 | */ | |
059ec3d9 PH |
1069 | |
1070 | if (expciphers != NULL) | |
1071 | { | |
1072 | uschar *s = expciphers; | |
1073 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } | |
1074 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); | |
1075 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) | |
7199e1ee | 1076 | return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL); |
7be682ca | 1077 | cbinfo->server_cipher_list = expciphers; |
059ec3d9 PH |
1078 | } |
1079 | ||
1080 | /* If this is a host for which certificate verification is mandatory or | |
1081 | optional, set up appropriately. */ | |
1082 | ||
1083 | tls_certificate_verified = FALSE; | |
1084 | verify_callback_called = FALSE; | |
1085 | ||
1086 | if (verify_check_host(&tls_verify_hosts) == OK) | |
1087 | { | |
7be682ca | 1088 | rc = setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, FALSE); |
059ec3d9 PH |
1089 | if (rc != OK) return rc; |
1090 | verify_optional = FALSE; | |
1091 | } | |
1092 | else if (verify_check_host(&tls_try_verify_hosts) == OK) | |
1093 | { | |
7be682ca | 1094 | rc = setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, TRUE); |
059ec3d9 PH |
1095 | if (rc != OK) return rc; |
1096 | verify_optional = TRUE; | |
1097 | } | |
1098 | ||
1099 | /* Prepare for new connection */ | |
1100 | ||
7199e1ee | 1101 | if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL); |
da3ad30d PP |
1102 | |
1103 | /* Warning: we used to SSL_clear(ssl) here, it was removed. | |
1104 | * | |
1105 | * With the SSL_clear(), we get strange interoperability bugs with | |
1106 | * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in | |
1107 | * OpenSSL itself, as a clear should not lead to inability to follow protocols. | |
1108 | * | |
1109 | * The SSL_clear() call is to let an existing SSL* be reused, typically after | |
1110 | * session shutdown. In this case, we have a brand new object and there's no | |
1111 | * obvious reason to immediately clear it. I'm guessing that this was | |
1112 | * originally added because of incomplete initialisation which the clear fixed, | |
1113 | * in some historic release. | |
1114 | */ | |
059ec3d9 PH |
1115 | |
1116 | /* Set context and tell client to go ahead, except in the case of TLS startup | |
1117 | on connection, where outputting anything now upsets the clients and tends to | |
1118 | make them disconnect. We need to have an explicit fflush() here, to force out | |
1119 | the response. Other smtp_printf() calls do not need it, because in non-TLS | |
1120 | mode, the fflush() happens when smtp_getc() is called. */ | |
1121 | ||
1122 | SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx)); | |
1123 | if (!tls_on_connect) | |
1124 | { | |
1125 | smtp_printf("220 TLS go ahead\r\n"); | |
1126 | fflush(smtp_out); | |
1127 | } | |
1128 | ||
1129 | /* Now negotiate the TLS session. We put our own timer on it, since it seems | |
1130 | that the OpenSSL library doesn't. */ | |
1131 | ||
56f5d9bd PH |
1132 | SSL_set_wfd(ssl, fileno(smtp_out)); |
1133 | SSL_set_rfd(ssl, fileno(smtp_in)); | |
059ec3d9 PH |
1134 | SSL_set_accept_state(ssl); |
1135 | ||
1136 | DEBUG(D_tls) debug_printf("Calling SSL_accept\n"); | |
1137 | ||
1138 | sigalrm_seen = FALSE; | |
1139 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
1140 | rc = SSL_accept(ssl); | |
1141 | alarm(0); | |
1142 | ||
1143 | if (rc <= 0) | |
1144 | { | |
7199e1ee | 1145 | tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL); |
77bb000f PP |
1146 | if (ERR_get_error() == 0) |
1147 | log_write(0, LOG_MAIN, | |
a053d125 | 1148 | "TLS client disconnected cleanly (rejected our certificate?)"); |
059ec3d9 PH |
1149 | return FAIL; |
1150 | } | |
1151 | ||
1152 | DEBUG(D_tls) debug_printf("SSL_accept was successful\n"); | |
1153 | ||
1154 | /* TLS has been set up. Adjust the input functions to read via TLS, | |
1155 | and initialize things. */ | |
1156 | ||
1157 | construct_cipher_name(ssl); | |
1158 | ||
1159 | DEBUG(D_tls) | |
1160 | { | |
1161 | uschar buf[2048]; | |
1162 | if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)) != NULL) | |
1163 | debug_printf("Shared ciphers: %s\n", buf); | |
1164 | } | |
1165 | ||
1166 | ||
1167 | ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size); | |
1168 | ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0; | |
1169 | ssl_xfer_eof = ssl_xfer_error = 0; | |
1170 | ||
1171 | receive_getc = tls_getc; | |
1172 | receive_ungetc = tls_ungetc; | |
1173 | receive_feof = tls_feof; | |
1174 | receive_ferror = tls_ferror; | |
58eb016e | 1175 | receive_smtp_buffered = tls_smtp_buffered; |
059ec3d9 PH |
1176 | |
1177 | tls_active = fileno(smtp_out); | |
1178 | return OK; | |
1179 | } | |
1180 | ||
1181 | ||
1182 | ||
1183 | ||
1184 | ||
1185 | /************************************************* | |
1186 | * Start a TLS session in a client * | |
1187 | *************************************************/ | |
1188 | ||
1189 | /* Called from the smtp transport after STARTTLS has been accepted. | |
1190 | ||
1191 | Argument: | |
1192 | fd the fd of the connection | |
1193 | host connected host (for messages) | |
83da1223 | 1194 | addr the first address |
059ec3d9 PH |
1195 | dhparam DH parameter file |
1196 | certificate certificate file | |
1197 | privatekey private key file | |
3f0945ff | 1198 | sni TLS SNI to send to remote host |
059ec3d9 PH |
1199 | verify_certs file for certificate verify |
1200 | crl file containing CRL | |
1201 | require_ciphers list of allowed ciphers | |
83da1223 | 1202 | timeout startup timeout |
059ec3d9 PH |
1203 | |
1204 | Returns: OK on success | |
1205 | FAIL otherwise - note that tls_error() will not give DEFER | |
1206 | because this is not a server | |
1207 | */ | |
1208 | ||
1209 | int | |
1210 | tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam, | |
3f0945ff PP |
1211 | uschar *certificate, uschar *privatekey, uschar *sni, |
1212 | uschar *verify_certs, uschar *crl, | |
17c76198 | 1213 | uschar *require_ciphers, int timeout) |
059ec3d9 PH |
1214 | { |
1215 | static uschar txt[256]; | |
1216 | uschar *expciphers; | |
1217 | X509* server_cert; | |
1218 | int rc; | |
1219 | ||
3f7eeb86 PP |
1220 | rc = tls_init(host, dhparam, certificate, privatekey, |
1221 | #ifdef EXPERIMENTAL_OCSP | |
1222 | NULL, | |
1223 | #endif | |
1224 | addr); | |
059ec3d9 PH |
1225 | if (rc != OK) return rc; |
1226 | ||
1227 | tls_certificate_verified = FALSE; | |
1228 | verify_callback_called = FALSE; | |
1229 | ||
1230 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers)) | |
1231 | return FAIL; | |
1232 | ||
1233 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they | |
1234 | are separated by underscores. So that I can use either form in my tests, and | |
1235 | also for general convenience, we turn underscores into hyphens here. */ | |
1236 | ||
1237 | if (expciphers != NULL) | |
1238 | { | |
1239 | uschar *s = expciphers; | |
1240 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } | |
1241 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); | |
1242 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) | |
7199e1ee | 1243 | return tls_error(US"SSL_CTX_set_cipher_list", host, NULL); |
059ec3d9 PH |
1244 | } |
1245 | ||
7be682ca | 1246 | rc = setup_certs(ctx, verify_certs, crl, host, FALSE); |
059ec3d9 PH |
1247 | if (rc != OK) return rc; |
1248 | ||
7199e1ee | 1249 | if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", host, NULL); |
059ec3d9 PH |
1250 | SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx)); |
1251 | SSL_set_fd(ssl, fd); | |
1252 | SSL_set_connect_state(ssl); | |
1253 | ||
3f0945ff PP |
1254 | if (sni) |
1255 | { | |
1256 | if (!expand_check(sni, US"tls_sni", &tls_sni)) | |
1257 | return FAIL; | |
1258 | if (!Ustrlen(tls_sni)) | |
1259 | tls_sni = NULL; | |
1260 | else | |
1261 | { | |
35731706 | 1262 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
3f0945ff PP |
1263 | DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_sni); |
1264 | SSL_set_tlsext_host_name(ssl, tls_sni); | |
35731706 PP |
1265 | #else |
1266 | DEBUG(D_tls) | |
1267 | debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n", | |
1268 | tls_sni); | |
1269 | #endif | |
3f0945ff PP |
1270 | } |
1271 | } | |
1272 | ||
059ec3d9 PH |
1273 | /* There doesn't seem to be a built-in timeout on connection. */ |
1274 | ||
1275 | DEBUG(D_tls) debug_printf("Calling SSL_connect\n"); | |
1276 | sigalrm_seen = FALSE; | |
1277 | alarm(timeout); | |
1278 | rc = SSL_connect(ssl); | |
1279 | alarm(0); | |
1280 | ||
1281 | if (rc <= 0) | |
7199e1ee | 1282 | return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL); |
059ec3d9 PH |
1283 | |
1284 | DEBUG(D_tls) debug_printf("SSL_connect succeeded\n"); | |
1285 | ||
453a6645 | 1286 | /* Beware anonymous ciphers which lead to server_cert being NULL */ |
059ec3d9 | 1287 | server_cert = SSL_get_peer_certificate (ssl); |
453a6645 PP |
1288 | if (server_cert) |
1289 | { | |
1290 | tls_peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert), | |
1291 | CS txt, sizeof(txt)); | |
1292 | tls_peerdn = txt; | |
1293 | } | |
1294 | else | |
1295 | tls_peerdn = NULL; | |
059ec3d9 PH |
1296 | |
1297 | construct_cipher_name(ssl); /* Sets tls_cipher */ | |
1298 | ||
1299 | tls_active = fd; | |
1300 | return OK; | |
1301 | } | |
1302 | ||
1303 | ||
1304 | ||
1305 | ||
1306 | ||
1307 | /************************************************* | |
1308 | * TLS version of getc * | |
1309 | *************************************************/ | |
1310 | ||
1311 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, | |
1312 | it refills the buffer via the SSL reading function. | |
1313 | ||
1314 | Arguments: none | |
1315 | Returns: the next character or EOF | |
1316 | */ | |
1317 | ||
1318 | int | |
1319 | tls_getc(void) | |
1320 | { | |
1321 | if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm) | |
1322 | { | |
1323 | int error; | |
1324 | int inbytes; | |
1325 | ||
c80c5570 PP |
1326 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl, |
1327 | ssl_xfer_buffer, ssl_xfer_buffer_size); | |
059ec3d9 PH |
1328 | |
1329 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
1330 | inbytes = SSL_read(ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size); | |
1331 | error = SSL_get_error(ssl, inbytes); | |
1332 | alarm(0); | |
1333 | ||
1334 | /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been | |
1335 | closed down, not that the socket itself has been closed down. Revert to | |
1336 | non-SSL handling. */ | |
1337 | ||
1338 | if (error == SSL_ERROR_ZERO_RETURN) | |
1339 | { | |
1340 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); | |
1341 | ||
1342 | receive_getc = smtp_getc; | |
1343 | receive_ungetc = smtp_ungetc; | |
1344 | receive_feof = smtp_feof; | |
1345 | receive_ferror = smtp_ferror; | |
58eb016e | 1346 | receive_smtp_buffered = smtp_buffered; |
059ec3d9 PH |
1347 | |
1348 | SSL_free(ssl); | |
1349 | ssl = NULL; | |
1350 | tls_active = -1; | |
3f0945ff | 1351 | tls_bits = 0; |
059ec3d9 PH |
1352 | tls_cipher = NULL; |
1353 | tls_peerdn = NULL; | |
3f0945ff | 1354 | tls_sni = NULL; |
059ec3d9 PH |
1355 | |
1356 | return smtp_getc(); | |
1357 | } | |
1358 | ||
1359 | /* Handle genuine errors */ | |
1360 | ||
ba084640 PP |
1361 | else if (error == SSL_ERROR_SSL) |
1362 | { | |
1363 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
89dd51cd | 1364 | log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring); |
ba084640 PP |
1365 | ssl_xfer_error = 1; |
1366 | return EOF; | |
1367 | } | |
1368 | ||
059ec3d9 PH |
1369 | else if (error != SSL_ERROR_NONE) |
1370 | { | |
1371 | DEBUG(D_tls) debug_printf("Got SSL error %d\n", error); | |
1372 | ssl_xfer_error = 1; | |
1373 | return EOF; | |
1374 | } | |
c80c5570 | 1375 | |
80a47a2c TK |
1376 | #ifndef DISABLE_DKIM |
1377 | dkim_exim_verify_feed(ssl_xfer_buffer, inbytes); | |
1378 | #endif | |
059ec3d9 PH |
1379 | ssl_xfer_buffer_hwm = inbytes; |
1380 | ssl_xfer_buffer_lwm = 0; | |
1381 | } | |
1382 | ||
1383 | /* Something in the buffer; return next uschar */ | |
1384 | ||
1385 | return ssl_xfer_buffer[ssl_xfer_buffer_lwm++]; | |
1386 | } | |
1387 | ||
1388 | ||
1389 | ||
1390 | /************************************************* | |
1391 | * Read bytes from TLS channel * | |
1392 | *************************************************/ | |
1393 | ||
1394 | /* | |
1395 | Arguments: | |
1396 | buff buffer of data | |
1397 | len size of buffer | |
1398 | ||
1399 | Returns: the number of bytes read | |
1400 | -1 after a failed read | |
1401 | */ | |
1402 | ||
1403 | int | |
1404 | tls_read(uschar *buff, size_t len) | |
1405 | { | |
1406 | int inbytes; | |
1407 | int error; | |
1408 | ||
c80c5570 PP |
1409 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl, |
1410 | buff, (unsigned int)len); | |
059ec3d9 PH |
1411 | |
1412 | inbytes = SSL_read(ssl, CS buff, len); | |
1413 | error = SSL_get_error(ssl, inbytes); | |
1414 | ||
1415 | if (error == SSL_ERROR_ZERO_RETURN) | |
1416 | { | |
1417 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); | |
1418 | return -1; | |
1419 | } | |
1420 | else if (error != SSL_ERROR_NONE) | |
1421 | { | |
1422 | return -1; | |
1423 | } | |
1424 | ||
1425 | return inbytes; | |
1426 | } | |
1427 | ||
1428 | ||
1429 | ||
1430 | ||
1431 | ||
1432 | /************************************************* | |
1433 | * Write bytes down TLS channel * | |
1434 | *************************************************/ | |
1435 | ||
1436 | /* | |
1437 | Arguments: | |
1438 | buff buffer of data | |
1439 | len number of bytes | |
1440 | ||
1441 | Returns: the number of bytes after a successful write, | |
1442 | -1 after a failed write | |
1443 | */ | |
1444 | ||
1445 | int | |
1446 | tls_write(const uschar *buff, size_t len) | |
1447 | { | |
1448 | int outbytes; | |
1449 | int error; | |
1450 | int left = len; | |
1451 | ||
c80c5570 | 1452 | DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left); |
059ec3d9 PH |
1453 | while (left > 0) |
1454 | { | |
c80c5570 | 1455 | DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left); |
059ec3d9 PH |
1456 | outbytes = SSL_write(ssl, CS buff, left); |
1457 | error = SSL_get_error(ssl, outbytes); | |
1458 | DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error); | |
1459 | switch (error) | |
1460 | { | |
1461 | case SSL_ERROR_SSL: | |
1462 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
1463 | log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring); | |
1464 | return -1; | |
1465 | ||
1466 | case SSL_ERROR_NONE: | |
1467 | left -= outbytes; | |
1468 | buff += outbytes; | |
1469 | break; | |
1470 | ||
1471 | case SSL_ERROR_ZERO_RETURN: | |
1472 | log_write(0, LOG_MAIN, "SSL channel closed on write"); | |
1473 | return -1; | |
1474 | ||
1475 | default: | |
1476 | log_write(0, LOG_MAIN, "SSL_write error %d", error); | |
1477 | return -1; | |
1478 | } | |
1479 | } | |
1480 | return len; | |
1481 | } | |
1482 | ||
1483 | ||
1484 | ||
1485 | /************************************************* | |
1486 | * Close down a TLS session * | |
1487 | *************************************************/ | |
1488 | ||
1489 | /* This is also called from within a delivery subprocess forked from the | |
1490 | daemon, to shut down the TLS library, without actually doing a shutdown (which | |
1491 | would tamper with the SSL session in the parent process). | |
1492 | ||
1493 | Arguments: TRUE if SSL_shutdown is to be called | |
1494 | Returns: nothing | |
1495 | */ | |
1496 | ||
1497 | void | |
1498 | tls_close(BOOL shutdown) | |
1499 | { | |
1500 | if (tls_active < 0) return; /* TLS was not active */ | |
1501 | ||
1502 | if (shutdown) | |
1503 | { | |
1504 | DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n"); | |
1505 | SSL_shutdown(ssl); | |
1506 | } | |
1507 | ||
1508 | SSL_free(ssl); | |
1509 | ssl = NULL; | |
1510 | ||
1511 | tls_active = -1; | |
1512 | } | |
1513 | ||
36f12725 NM |
1514 | |
1515 | ||
1516 | ||
3375e053 PP |
1517 | /************************************************* |
1518 | * Let tls_require_ciphers be checked at startup * | |
1519 | *************************************************/ | |
1520 | ||
1521 | /* The tls_require_ciphers option, if set, must be something which the | |
1522 | library can parse. | |
1523 | ||
1524 | Returns: NULL on success, or error message | |
1525 | */ | |
1526 | ||
1527 | uschar * | |
1528 | tls_validate_require_cipher(void) | |
1529 | { | |
1530 | SSL_CTX *ctx; | |
1531 | uschar *s, *expciphers, *err; | |
1532 | ||
1533 | /* this duplicates from tls_init(), we need a better "init just global | |
1534 | state, for no specific purpose" singleton function of our own */ | |
1535 | ||
1536 | SSL_load_error_strings(); | |
1537 | OpenSSL_add_ssl_algorithms(); | |
1538 | #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256) | |
1539 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the | |
1540 | list of available digests. */ | |
1541 | EVP_add_digest(EVP_sha256()); | |
1542 | #endif | |
1543 | ||
1544 | if (!(tls_require_ciphers && *tls_require_ciphers)) | |
1545 | return NULL; | |
1546 | ||
1547 | if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers)) | |
1548 | return US"failed to expand tls_require_ciphers"; | |
1549 | ||
1550 | if (!(expciphers && *expciphers)) | |
1551 | return NULL; | |
1552 | ||
1553 | /* normalisation ripped from above */ | |
1554 | s = expciphers; | |
1555 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } | |
1556 | ||
1557 | err = NULL; | |
1558 | ||
1559 | ctx = SSL_CTX_new(SSLv23_server_method()); | |
1560 | if (!ctx) | |
1561 | { | |
1562 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
1563 | return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring); | |
1564 | } | |
1565 | ||
1566 | DEBUG(D_tls) | |
1567 | debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers); | |
1568 | ||
1569 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) | |
1570 | { | |
1571 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
1572 | err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers); | |
1573 | } | |
1574 | ||
1575 | SSL_CTX_free(ctx); | |
1576 | ||
1577 | return err; | |
1578 | } | |
1579 | ||
1580 | ||
1581 | ||
1582 | ||
36f12725 NM |
1583 | /************************************************* |
1584 | * Report the library versions. * | |
1585 | *************************************************/ | |
1586 | ||
1587 | /* There have historically been some issues with binary compatibility in | |
1588 | OpenSSL libraries; if Exim (like many other applications) is built against | |
1589 | one version of OpenSSL but the run-time linker picks up another version, | |
1590 | it can result in serious failures, including crashing with a SIGSEGV. So | |
1591 | report the version found by the compiler and the run-time version. | |
1592 | ||
1593 | Arguments: a FILE* to print the results to | |
1594 | Returns: nothing | |
1595 | */ | |
1596 | ||
1597 | void | |
1598 | tls_version_report(FILE *f) | |
1599 | { | |
754a0503 PP |
1600 | fprintf(f, "Library version: OpenSSL: Compile: %s\n" |
1601 | " Runtime: %s\n", | |
1602 | OPENSSL_VERSION_TEXT, | |
1603 | SSLeay_version(SSLEAY_VERSION)); | |
36f12725 NM |
1604 | } |
1605 | ||
9e3331ea TK |
1606 | |
1607 | ||
1608 | ||
1609 | /************************************************* | |
17c76198 | 1610 | * Random number generation * |
9e3331ea TK |
1611 | *************************************************/ |
1612 | ||
1613 | /* Pseudo-random number generation. The result is not expected to be | |
1614 | cryptographically strong but not so weak that someone will shoot themselves | |
1615 | in the foot using it as a nonce in input in some email header scheme or | |
1616 | whatever weirdness they'll twist this into. The result should handle fork() | |
1617 | and avoid repeating sequences. OpenSSL handles that for us. | |
1618 | ||
1619 | Arguments: | |
1620 | max range maximum | |
1621 | Returns a random number in range [0, max-1] | |
1622 | */ | |
1623 | ||
1624 | int | |
17c76198 | 1625 | vaguely_random_number(int max) |
9e3331ea TK |
1626 | { |
1627 | unsigned int r; | |
1628 | int i, needed_len; | |
1629 | uschar *p; | |
1630 | uschar smallbuf[sizeof(r)]; | |
1631 | ||
1632 | if (max <= 1) | |
1633 | return 0; | |
1634 | ||
1635 | /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */ | |
1636 | if (!RAND_status()) | |
1637 | { | |
1638 | randstuff r; | |
1639 | gettimeofday(&r.tv, NULL); | |
1640 | r.p = getpid(); | |
1641 | ||
1642 | RAND_seed((uschar *)(&r), sizeof(r)); | |
1643 | } | |
1644 | /* We're after pseudo-random, not random; if we still don't have enough data | |
1645 | in the internal PRNG then our options are limited. We could sleep and hope | |
1646 | for entropy to come along (prayer technique) but if the system is so depleted | |
1647 | in the first place then something is likely to just keep taking it. Instead, | |
1648 | we'll just take whatever little bit of pseudo-random we can still manage to | |
1649 | get. */ | |
1650 | ||
1651 | needed_len = sizeof(r); | |
1652 | /* Don't take 8 times more entropy than needed if int is 8 octets and we were | |
1653 | asked for a number less than 10. */ | |
1654 | for (r = max, i = 0; r; ++i) | |
1655 | r >>= 1; | |
1656 | i = (i + 7) / 8; | |
1657 | if (i < needed_len) | |
1658 | needed_len = i; | |
1659 | ||
1660 | /* We do not care if crypto-strong */ | |
17c76198 PP |
1661 | i = RAND_pseudo_bytes(smallbuf, needed_len); |
1662 | if (i < 0) | |
1663 | { | |
1664 | DEBUG(D_all) | |
1665 | debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n"); | |
1666 | return vaguely_random_number_fallback(max); | |
1667 | } | |
1668 | ||
9e3331ea TK |
1669 | r = 0; |
1670 | for (p = smallbuf; needed_len; --needed_len, ++p) | |
1671 | { | |
1672 | r *= 256; | |
1673 | r += *p; | |
1674 | } | |
1675 | ||
1676 | /* We don't particularly care about weighted results; if someone wants | |
1677 | smooth distribution and cares enough then they should submit a patch then. */ | |
1678 | return r % max; | |
1679 | } | |
1680 | ||
77bb000f PP |
1681 | |
1682 | ||
1683 | ||
1684 | /************************************************* | |
1685 | * OpenSSL option parse * | |
1686 | *************************************************/ | |
1687 | ||
1688 | /* Parse one option for tls_openssl_options_parse below | |
1689 | ||
1690 | Arguments: | |
1691 | name one option name | |
1692 | value place to store a value for it | |
1693 | Returns success or failure in parsing | |
1694 | */ | |
1695 | ||
1696 | struct exim_openssl_option { | |
1697 | uschar *name; | |
1698 | long value; | |
1699 | }; | |
1700 | /* We could use a macro to expand, but we need the ifdef and not all the | |
1701 | options document which version they were introduced in. Policylet: include | |
1702 | all options unless explicitly for DTLS, let the administrator choose which | |
1703 | to apply. | |
1704 | ||
1705 | This list is current as of: | |
c80c5570 | 1706 | ==> 1.0.1b <== */ |
77bb000f PP |
1707 | static struct exim_openssl_option exim_openssl_options[] = { |
1708 | /* KEEP SORTED ALPHABETICALLY! */ | |
1709 | #ifdef SSL_OP_ALL | |
73a46702 | 1710 | { US"all", SSL_OP_ALL }, |
77bb000f PP |
1711 | #endif |
1712 | #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION | |
73a46702 | 1713 | { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION }, |
77bb000f PP |
1714 | #endif |
1715 | #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE | |
73a46702 | 1716 | { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE }, |
77bb000f PP |
1717 | #endif |
1718 | #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS | |
73a46702 | 1719 | { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS }, |
77bb000f PP |
1720 | #endif |
1721 | #ifdef SSL_OP_EPHEMERAL_RSA | |
73a46702 | 1722 | { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA }, |
77bb000f PP |
1723 | #endif |
1724 | #ifdef SSL_OP_LEGACY_SERVER_CONNECT | |
73a46702 | 1725 | { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT }, |
77bb000f PP |
1726 | #endif |
1727 | #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER | |
73a46702 | 1728 | { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER }, |
77bb000f PP |
1729 | #endif |
1730 | #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG | |
73a46702 | 1731 | { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG }, |
77bb000f PP |
1732 | #endif |
1733 | #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING | |
73a46702 | 1734 | { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING }, |
77bb000f PP |
1735 | #endif |
1736 | #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG | |
73a46702 | 1737 | { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG }, |
77bb000f PP |
1738 | #endif |
1739 | #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG | |
73a46702 | 1740 | { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG }, |
77bb000f | 1741 | #endif |
c80c5570 PP |
1742 | #ifdef SSL_OP_NO_COMPRESSION |
1743 | { US"no_compression", SSL_OP_NO_COMPRESSION }, | |
1744 | #endif | |
77bb000f | 1745 | #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION |
73a46702 | 1746 | { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION }, |
77bb000f | 1747 | #endif |
c0c7b2da PP |
1748 | #ifdef SSL_OP_NO_SSLv2 |
1749 | { US"no_sslv2", SSL_OP_NO_SSLv2 }, | |
1750 | #endif | |
1751 | #ifdef SSL_OP_NO_SSLv3 | |
1752 | { US"no_sslv3", SSL_OP_NO_SSLv3 }, | |
1753 | #endif | |
1754 | #ifdef SSL_OP_NO_TICKET | |
1755 | { US"no_ticket", SSL_OP_NO_TICKET }, | |
1756 | #endif | |
1757 | #ifdef SSL_OP_NO_TLSv1 | |
1758 | { US"no_tlsv1", SSL_OP_NO_TLSv1 }, | |
1759 | #endif | |
c80c5570 PP |
1760 | #ifdef SSL_OP_NO_TLSv1_1 |
1761 | #if SSL_OP_NO_TLSv1_1 == 0x00000400L | |
1762 | /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */ | |
1763 | #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring | |
1764 | #else | |
1765 | { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 }, | |
1766 | #endif | |
1767 | #endif | |
1768 | #ifdef SSL_OP_NO_TLSv1_2 | |
1769 | { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 }, | |
1770 | #endif | |
77bb000f | 1771 | #ifdef SSL_OP_SINGLE_DH_USE |
73a46702 | 1772 | { US"single_dh_use", SSL_OP_SINGLE_DH_USE }, |
77bb000f PP |
1773 | #endif |
1774 | #ifdef SSL_OP_SINGLE_ECDH_USE | |
73a46702 | 1775 | { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE }, |
77bb000f PP |
1776 | #endif |
1777 | #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG | |
73a46702 | 1778 | { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG }, |
77bb000f PP |
1779 | #endif |
1780 | #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG | |
73a46702 | 1781 | { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG }, |
77bb000f PP |
1782 | #endif |
1783 | #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG | |
73a46702 | 1784 | { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG }, |
77bb000f PP |
1785 | #endif |
1786 | #ifdef SSL_OP_TLS_D5_BUG | |
73a46702 | 1787 | { US"tls_d5_bug", SSL_OP_TLS_D5_BUG }, |
77bb000f PP |
1788 | #endif |
1789 | #ifdef SSL_OP_TLS_ROLLBACK_BUG | |
73a46702 | 1790 | { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG }, |
77bb000f PP |
1791 | #endif |
1792 | }; | |
1793 | static int exim_openssl_options_size = | |
1794 | sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option); | |
1795 | ||
c80c5570 | 1796 | |
77bb000f PP |
1797 | static BOOL |
1798 | tls_openssl_one_option_parse(uschar *name, long *value) | |
1799 | { | |
1800 | int first = 0; | |
1801 | int last = exim_openssl_options_size; | |
1802 | while (last > first) | |
1803 | { | |
1804 | int middle = (first + last)/2; | |
1805 | int c = Ustrcmp(name, exim_openssl_options[middle].name); | |
1806 | if (c == 0) | |
1807 | { | |
1808 | *value = exim_openssl_options[middle].value; | |
1809 | return TRUE; | |
1810 | } | |
1811 | else if (c > 0) | |
1812 | first = middle + 1; | |
1813 | else | |
1814 | last = middle; | |
1815 | } | |
1816 | return FALSE; | |
1817 | } | |
1818 | ||
1819 | ||
1820 | ||
1821 | ||
1822 | /************************************************* | |
1823 | * OpenSSL option parsing logic * | |
1824 | *************************************************/ | |
1825 | ||
1826 | /* OpenSSL has a number of compatibility options which an administrator might | |
1827 | reasonably wish to set. Interpret a list similarly to decode_bits(), so that | |
1828 | we look like log_selector. | |
1829 | ||
1830 | Arguments: | |
1831 | option_spec the administrator-supplied string of options | |
1832 | results ptr to long storage for the options bitmap | |
1833 | Returns success or failure | |
1834 | */ | |
1835 | ||
1836 | BOOL | |
1837 | tls_openssl_options_parse(uschar *option_spec, long *results) | |
1838 | { | |
1839 | long result, item; | |
1840 | uschar *s, *end; | |
1841 | uschar keep_c; | |
1842 | BOOL adding, item_parsed; | |
1843 | ||
0e944a0d | 1844 | result = 0L; |
b1770b6e | 1845 | /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed |
da3ad30d | 1846 | * from default because it increases BEAST susceptibility. */ |
77bb000f PP |
1847 | |
1848 | if (option_spec == NULL) | |
1849 | { | |
1850 | *results = result; | |
1851 | return TRUE; | |
1852 | } | |
1853 | ||
1854 | for (s=option_spec; *s != '\0'; /**/) | |
1855 | { | |
1856 | while (isspace(*s)) ++s; | |
1857 | if (*s == '\0') | |
1858 | break; | |
1859 | if (*s != '+' && *s != '-') | |
1860 | { | |
1861 | DEBUG(D_tls) debug_printf("malformed openssl option setting: " | |
0e944a0d | 1862 | "+ or - expected but found \"%s\"\n", s); |
77bb000f PP |
1863 | return FALSE; |
1864 | } | |
1865 | adding = *s++ == '+'; | |
1866 | for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ; | |
1867 | keep_c = *end; | |
1868 | *end = '\0'; | |
1869 | item_parsed = tls_openssl_one_option_parse(s, &item); | |
1870 | if (!item_parsed) | |
1871 | { | |
0e944a0d | 1872 | DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s); |
77bb000f PP |
1873 | return FALSE; |
1874 | } | |
1875 | DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n", | |
1876 | adding ? "adding" : "removing", result, item, s); | |
1877 | if (adding) | |
1878 | result |= item; | |
1879 | else | |
1880 | result &= ~item; | |
1881 | *end = keep_c; | |
1882 | s = end; | |
1883 | } | |
1884 | ||
1885 | *results = result; | |
1886 | return TRUE; | |
1887 | } | |
1888 | ||
059ec3d9 | 1889 | /* End of tls-openssl.c */ |