Commit | Line | Data |
---|---|---|
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 | ||
a2ff477a JH |
45 | static BOOL client_verify_callback_called = FALSE; |
46 | static BOOL server_verify_callback_called = FALSE; | |
059ec3d9 PH |
47 | static const uschar *sid_ctx = US"exim"; |
48 | ||
817d9f57 JH |
49 | static SSL_CTX *client_ctx = NULL; |
50 | static SSL_CTX *server_ctx = NULL; | |
51 | static SSL *client_ssl = NULL; | |
52 | static SSL *server_ssl = NULL; | |
389ca47a | 53 | |
35731706 | 54 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
817d9f57 JH |
55 | static SSL_CTX *client_sni = NULL; |
56 | static SSL_CTX *server_sni = NULL; | |
35731706 | 57 | #endif |
059ec3d9 PH |
58 | |
59 | static char ssl_errstring[256]; | |
60 | ||
61 | static int ssl_session_timeout = 200; | |
a2ff477a JH |
62 | static BOOL client_verify_optional = FALSE; |
63 | static BOOL server_verify_optional = FALSE; | |
059ec3d9 | 64 | |
7be682ca | 65 | static BOOL reexpand_tls_files_for_sni = FALSE; |
059ec3d9 PH |
66 | |
67 | ||
7be682ca PP |
68 | typedef struct tls_ext_ctx_cb { |
69 | uschar *certificate; | |
70 | uschar *privatekey; | |
3f7eeb86 PP |
71 | #ifdef EXPERIMENTAL_OCSP |
72 | uschar *ocsp_file; | |
73 | uschar *ocsp_file_expanded; | |
74 | OCSP_RESPONSE *ocsp_response; | |
75 | #endif | |
7be682ca PP |
76 | uschar *dhparam; |
77 | /* these are cached from first expand */ | |
78 | uschar *server_cipher_list; | |
79 | /* only passed down to tls_error: */ | |
80 | host_item *host; | |
81 | } tls_ext_ctx_cb; | |
82 | ||
83 | /* should figure out a cleanup of API to handle state preserved per | |
84 | implementation, for various reasons, which can be void * in the APIs. | |
85 | For now, we hack around it. */ | |
817d9f57 JH |
86 | tls_ext_ctx_cb *client_static_cbinfo = NULL; |
87 | tls_ext_ctx_cb *server_static_cbinfo = NULL; | |
7be682ca PP |
88 | |
89 | static int | |
a2ff477a | 90 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional, BOOL client); |
059ec3d9 | 91 | |
3f7eeb86 | 92 | /* Callbacks */ |
3bcbbbe2 | 93 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
3f7eeb86 | 94 | static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg); |
3bcbbbe2 | 95 | #endif |
3f7eeb86 PP |
96 | #ifdef EXPERIMENTAL_OCSP |
97 | static int tls_stapling_cb(SSL *s, void *arg); | |
98 | #endif | |
99 | ||
059ec3d9 PH |
100 | |
101 | /************************************************* | |
102 | * Handle TLS error * | |
103 | *************************************************/ | |
104 | ||
105 | /* Called from lots of places when errors occur before actually starting to do | |
106 | the TLS handshake, that is, while the session is still in clear. Always returns | |
107 | DEFER for a server and FAIL for a client so that most calls can use "return | |
108 | tls_error(...)" to do this processing and then give an appropriate return. A | |
109 | single function is used for both server and client, because it is called from | |
110 | some shared functions. | |
111 | ||
112 | Argument: | |
113 | prefix text to include in the logged error | |
114 | host NULL if setting up a server; | |
115 | the connected host if setting up a client | |
7199e1ee | 116 | msg error message or NULL if we should ask OpenSSL |
059ec3d9 PH |
117 | |
118 | Returns: OK/DEFER/FAIL | |
119 | */ | |
120 | ||
121 | static int | |
7199e1ee | 122 | tls_error(uschar *prefix, host_item *host, uschar *msg) |
059ec3d9 | 123 | { |
7199e1ee TF |
124 | if (msg == NULL) |
125 | { | |
126 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
5ca6d115 | 127 | msg = (uschar *)ssl_errstring; |
7199e1ee TF |
128 | } |
129 | ||
059ec3d9 PH |
130 | if (host == NULL) |
131 | { | |
7199e1ee | 132 | uschar *conn_info = smtp_get_connection_info(); |
5ca6d115 | 133 | if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) |
7199e1ee TF |
134 | conn_info += 5; |
135 | log_write(0, LOG_MAIN, "TLS error on %s (%s): %s", | |
136 | conn_info, prefix, msg); | |
059ec3d9 PH |
137 | return DEFER; |
138 | } | |
139 | else | |
140 | { | |
141 | log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s): %s", | |
7199e1ee | 142 | host->name, host->address, prefix, msg); |
059ec3d9 PH |
143 | return FAIL; |
144 | } | |
145 | } | |
146 | ||
147 | ||
148 | ||
149 | /************************************************* | |
150 | * Callback to generate RSA key * | |
151 | *************************************************/ | |
152 | ||
153 | /* | |
154 | Arguments: | |
155 | s SSL connection | |
156 | export not used | |
157 | keylength keylength | |
158 | ||
159 | Returns: pointer to generated key | |
160 | */ | |
161 | ||
162 | static RSA * | |
163 | rsa_callback(SSL *s, int export, int keylength) | |
164 | { | |
165 | RSA *rsa_key; | |
166 | export = export; /* Shut picky compilers up */ | |
167 | DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength); | |
168 | rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL); | |
169 | if (rsa_key == NULL) | |
170 | { | |
171 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
172 | log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s", | |
173 | ssl_errstring); | |
174 | return NULL; | |
175 | } | |
176 | return rsa_key; | |
177 | } | |
178 | ||
179 | ||
180 | ||
181 | ||
182 | /************************************************* | |
183 | * Callback for verification * | |
184 | *************************************************/ | |
185 | ||
186 | /* The SSL library does certificate verification if set up to do so. This | |
187 | callback has the current yes/no state is in "state". If verification succeeded, | |
188 | we set up the tls_peerdn string. If verification failed, what happens depends | |
189 | on whether the client is required to present a verifiable certificate or not. | |
190 | ||
191 | If verification is optional, we change the state to yes, but still log the | |
192 | verification error. For some reason (it really would help to have proper | |
193 | documentation of OpenSSL), this callback function then gets called again, this | |
194 | time with state = 1. In fact, that's useful, because we can set up the peerdn | |
195 | value, but we must take care not to set the private verified flag on the second | |
196 | time through. | |
197 | ||
198 | Note: this function is not called if the client fails to present a certificate | |
199 | when asked. We get here only if a certificate has been received. Handling of | |
200 | optional verification for this case is done when requesting SSL to verify, by | |
201 | setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case. | |
202 | ||
203 | Arguments: | |
204 | state current yes/no state as 1/0 | |
205 | x509ctx certificate information. | |
a2ff477a | 206 | client TRUE for client startup, FALSE for server startup |
059ec3d9 PH |
207 | |
208 | Returns: 1 if verified, 0 if not | |
209 | */ | |
210 | ||
211 | static int | |
a2ff477a | 212 | verify_callback(int state, X509_STORE_CTX *x509ctx, BOOL client) |
059ec3d9 PH |
213 | { |
214 | static uschar txt[256]; | |
a2ff477a JH |
215 | tls_support * tlsp; |
216 | BOOL * calledp; | |
217 | BOOL * optionalp; | |
218 | ||
219 | if (client) | |
220 | { | |
221 | tlsp= &tls_out; | |
222 | calledp= &client_verify_callback_called; | |
223 | optionalp= &client_verify_optional; | |
224 | } | |
225 | else | |
226 | { | |
227 | tlsp= &tls_in; | |
228 | calledp= &server_verify_callback_called; | |
229 | optionalp= &server_verify_optional; | |
230 | } | |
059ec3d9 PH |
231 | |
232 | X509_NAME_oneline(X509_get_subject_name(x509ctx->current_cert), | |
233 | CS txt, sizeof(txt)); | |
234 | ||
235 | if (state == 0) | |
236 | { | |
237 | log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s", | |
238 | x509ctx->error_depth, | |
239 | X509_verify_cert_error_string(x509ctx->error), | |
240 | txt); | |
a2ff477a JH |
241 | tlsp->certificate_verified = FALSE; |
242 | *calledp = TRUE; | |
243 | if (!*optionalp) return 0; /* reject */ | |
059ec3d9 PH |
244 | DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in " |
245 | "tls_try_verify_hosts)\n"); | |
246 | return 1; /* accept */ | |
247 | } | |
248 | ||
249 | if (x509ctx->error_depth != 0) | |
250 | { | |
251 | DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d cert=%s\n", | |
252 | x509ctx->error_depth, txt); | |
253 | } | |
254 | else | |
255 | { | |
256 | DEBUG(D_tls) debug_printf("SSL%s peer: %s\n", | |
a2ff477a JH |
257 | *calledp ? "" : " authenticated", txt); |
258 | tlsp->peerdn = txt; | |
059ec3d9 PH |
259 | } |
260 | ||
a2ff477a JH |
261 | if (!*calledp) tlsp->certificate_verified = TRUE; |
262 | *calledp = TRUE; | |
059ec3d9 PH |
263 | |
264 | return 1; /* accept */ | |
265 | } | |
266 | ||
a2ff477a JH |
267 | static int |
268 | verify_callback_client(int state, X509_STORE_CTX *x509ctx) | |
269 | { | |
270 | return verify_callback(state, x509ctx, TRUE); | |
271 | } | |
272 | ||
273 | static int | |
274 | verify_callback_server(int state, X509_STORE_CTX *x509ctx) | |
275 | { | |
276 | return verify_callback(state, x509ctx, FALSE); | |
277 | } | |
278 | ||
059ec3d9 PH |
279 | |
280 | ||
281 | /************************************************* | |
282 | * Information callback * | |
283 | *************************************************/ | |
284 | ||
285 | /* The SSL library functions call this from time to time to indicate what they | |
7be682ca PP |
286 | are doing. We copy the string to the debugging output when TLS debugging has |
287 | been requested. | |
059ec3d9 PH |
288 | |
289 | Arguments: | |
290 | s the SSL connection | |
291 | where | |
292 | ret | |
293 | ||
294 | Returns: nothing | |
295 | */ | |
296 | ||
297 | static void | |
298 | info_callback(SSL *s, int where, int ret) | |
299 | { | |
300 | where = where; | |
301 | ret = ret; | |
302 | DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s)); | |
303 | } | |
304 | ||
305 | ||
306 | ||
307 | /************************************************* | |
308 | * Initialize for DH * | |
309 | *************************************************/ | |
310 | ||
311 | /* If dhparam is set, expand it, and load up the parameters for DH encryption. | |
312 | ||
313 | Arguments: | |
a799883d | 314 | dhparam DH parameter file or fixed parameter identity string |
7199e1ee | 315 | host connected host, if client; NULL if server |
059ec3d9 PH |
316 | |
317 | Returns: TRUE if OK (nothing to set up, or setup worked) | |
318 | */ | |
319 | ||
320 | static BOOL | |
a799883d | 321 | init_dh(SSL_CTX *sctx, uschar *dhparam, host_item *host) |
059ec3d9 | 322 | { |
059ec3d9 PH |
323 | BIO *bio; |
324 | DH *dh; | |
325 | uschar *dhexpanded; | |
a799883d | 326 | const char *pem; |
059ec3d9 PH |
327 | |
328 | if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded)) | |
329 | return FALSE; | |
330 | ||
a799883d | 331 | if (dhexpanded == NULL || *dhexpanded == '\0') |
059ec3d9 | 332 | { |
a799883d | 333 | bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1); |
059ec3d9 | 334 | } |
a799883d | 335 | else if (dhexpanded[0] == '/') |
059ec3d9 | 336 | { |
a799883d PP |
337 | bio = BIO_new_file(CS dhexpanded, "r"); |
338 | if (bio == NULL) | |
059ec3d9 | 339 | { |
7199e1ee | 340 | tls_error(string_sprintf("could not read dhparams file %s", dhexpanded), |
a799883d PP |
341 | host, US strerror(errno)); |
342 | return FALSE; | |
059ec3d9 | 343 | } |
a799883d PP |
344 | } |
345 | else | |
346 | { | |
347 | if (Ustrcmp(dhexpanded, "none") == 0) | |
059ec3d9 | 348 | { |
a799883d PP |
349 | DEBUG(D_tls) debug_printf("Requested no DH parameters.\n"); |
350 | return TRUE; | |
059ec3d9 | 351 | } |
a799883d PP |
352 | |
353 | pem = std_dh_prime_named(dhexpanded); | |
354 | if (!pem) | |
355 | { | |
356 | tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded), | |
357 | host, US strerror(errno)); | |
358 | return FALSE; | |
359 | } | |
360 | bio = BIO_new_mem_buf(CS pem, -1); | |
361 | } | |
362 | ||
363 | dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL); | |
364 | if (dh == NULL) | |
365 | { | |
059ec3d9 | 366 | BIO_free(bio); |
a799883d PP |
367 | tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded), |
368 | host, NULL); | |
369 | return FALSE; | |
370 | } | |
371 | ||
372 | /* Even if it is larger, we silently return success rather than cause things | |
373 | * to fail out, so that a too-large DH will not knock out all TLS; it's a | |
374 | * debatable choice. */ | |
375 | if ((8*DH_size(dh)) > tls_dh_max_bits) | |
376 | { | |
377 | DEBUG(D_tls) | |
378 | debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d", | |
379 | 8*DH_size(dh), tls_dh_max_bits); | |
380 | } | |
381 | else | |
382 | { | |
383 | SSL_CTX_set_tmp_dh(sctx, dh); | |
384 | DEBUG(D_tls) | |
385 | debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n", | |
386 | dhexpanded ? dhexpanded : US"default", 8*DH_size(dh)); | |
059ec3d9 PH |
387 | } |
388 | ||
a799883d PP |
389 | DH_free(dh); |
390 | BIO_free(bio); | |
391 | ||
392 | return TRUE; | |
059ec3d9 PH |
393 | } |
394 | ||
395 | ||
396 | ||
397 | ||
3f7eeb86 PP |
398 | #ifdef EXPERIMENTAL_OCSP |
399 | /************************************************* | |
400 | * Load OCSP information into state * | |
401 | *************************************************/ | |
402 | ||
403 | /* Called to load the OCSP response from the given file into memory, once | |
404 | caller has determined this is needed. Checks validity. Debugs a message | |
405 | if invalid. | |
406 | ||
407 | ASSUMES: single response, for single cert. | |
408 | ||
409 | Arguments: | |
410 | sctx the SSL_CTX* to update | |
411 | cbinfo various parts of session state | |
412 | expanded the filename putatively holding an OCSP response | |
413 | ||
414 | */ | |
415 | ||
416 | static void | |
417 | ocsp_load_response(SSL_CTX *sctx, | |
418 | tls_ext_ctx_cb *cbinfo, | |
419 | const uschar *expanded) | |
420 | { | |
421 | BIO *bio; | |
422 | OCSP_RESPONSE *resp; | |
423 | OCSP_BASICRESP *basic_response; | |
424 | OCSP_SINGLERESP *single_response; | |
425 | ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd; | |
426 | X509_STORE *store; | |
427 | unsigned long verify_flags; | |
428 | int status, reason, i; | |
429 | ||
430 | cbinfo->ocsp_file_expanded = string_copy(expanded); | |
431 | if (cbinfo->ocsp_response) | |
432 | { | |
433 | OCSP_RESPONSE_free(cbinfo->ocsp_response); | |
434 | cbinfo->ocsp_response = NULL; | |
435 | } | |
436 | ||
437 | bio = BIO_new_file(CS cbinfo->ocsp_file_expanded, "rb"); | |
438 | if (!bio) | |
439 | { | |
440 | DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n", | |
441 | cbinfo->ocsp_file_expanded); | |
442 | return; | |
443 | } | |
444 | ||
445 | resp = d2i_OCSP_RESPONSE_bio(bio, NULL); | |
446 | BIO_free(bio); | |
447 | if (!resp) | |
448 | { | |
449 | DEBUG(D_tls) debug_printf("Error reading OCSP response.\n"); | |
450 | return; | |
451 | } | |
452 | ||
453 | status = OCSP_response_status(resp); | |
454 | if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL) | |
455 | { | |
456 | DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n", | |
457 | OCSP_response_status_str(status), status); | |
458 | return; | |
459 | } | |
460 | ||
461 | basic_response = OCSP_response_get1_basic(resp); | |
462 | if (!basic_response) | |
463 | { | |
464 | DEBUG(D_tls) | |
465 | debug_printf("OCSP response parse error: unable to extract basic response.\n"); | |
466 | return; | |
467 | } | |
468 | ||
469 | store = SSL_CTX_get_cert_store(sctx); | |
470 | verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */ | |
471 | ||
472 | /* May need to expose ability to adjust those flags? | |
473 | OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT | |
474 | OCSP_TRUSTOTHER OCSP_NOINTERN */ | |
475 | ||
476 | i = OCSP_basic_verify(basic_response, NULL, store, verify_flags); | |
477 | if (i <= 0) | |
478 | { | |
479 | DEBUG(D_tls) { | |
480 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
481 | debug_printf("OCSP response verify failure: %s\n", US ssl_errstring); | |
482 | } | |
483 | return; | |
484 | } | |
485 | ||
486 | /* Here's the simplifying assumption: there's only one response, for the | |
487 | one certificate we use, and nothing for anything else in a chain. If this | |
488 | proves false, we need to extract a cert id from our issued cert | |
489 | (tls_certificate) and use that for OCSP_resp_find_status() (which finds the | |
490 | right cert in the stack and then calls OCSP_single_get0_status()). | |
491 | ||
492 | I'm hoping to avoid reworking a bunch more of how we handle state here. */ | |
493 | single_response = OCSP_resp_get0(basic_response, 0); | |
494 | if (!single_response) | |
495 | { | |
496 | DEBUG(D_tls) | |
497 | debug_printf("Unable to get first response from OCSP basic response.\n"); | |
498 | return; | |
499 | } | |
500 | ||
501 | status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd); | |
502 | /* how does this status differ from the one above? */ | |
503 | if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL) | |
504 | { | |
505 | DEBUG(D_tls) debug_printf("OCSP response not valid (take 2): %s (%d)\n", | |
506 | OCSP_response_status_str(status), status); | |
507 | return; | |
508 | } | |
509 | ||
510 | if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE)) | |
511 | { | |
512 | DEBUG(D_tls) debug_printf("OCSP status invalid times.\n"); | |
513 | return; | |
514 | } | |
515 | ||
516 | cbinfo->ocsp_response = resp; | |
517 | } | |
518 | #endif | |
519 | ||
520 | ||
521 | ||
522 | ||
7be682ca PP |
523 | /************************************************* |
524 | * Expand key and cert file specs * | |
525 | *************************************************/ | |
526 | ||
527 | /* Called once during tls_init and possibly againt during TLS setup, for a | |
528 | new context, if Server Name Indication was used and tls_sni was seen in | |
529 | the certificate string. | |
530 | ||
531 | Arguments: | |
532 | sctx the SSL_CTX* to update | |
533 | cbinfo various parts of session state | |
534 | ||
535 | Returns: OK/DEFER/FAIL | |
536 | */ | |
537 | ||
538 | static int | |
3f7eeb86 | 539 | tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo) |
7be682ca PP |
540 | { |
541 | uschar *expanded; | |
542 | ||
543 | if (cbinfo->certificate == NULL) | |
544 | return OK; | |
545 | ||
d9b2312b JH |
546 | if (Ustrstr(cbinfo->certificate, US"tls_sni") || |
547 | Ustrstr(cbinfo->certificate, US"tls_in_sni") || | |
548 | Ustrstr(cbinfo->certificate, US"tls_out_sni") | |
549 | ) | |
7be682ca PP |
550 | reexpand_tls_files_for_sni = TRUE; |
551 | ||
552 | if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded)) | |
553 | return DEFER; | |
554 | ||
555 | if (expanded != NULL) | |
556 | { | |
557 | DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded); | |
558 | if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded)) | |
559 | return tls_error(string_sprintf( | |
560 | "SSL_CTX_use_certificate_chain_file file=%s", expanded), | |
561 | cbinfo->host, NULL); | |
562 | } | |
563 | ||
564 | if (cbinfo->privatekey != NULL && | |
565 | !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded)) | |
566 | return DEFER; | |
567 | ||
568 | /* If expansion was forced to fail, key_expanded will be NULL. If the result | |
569 | of the expansion is an empty string, ignore it also, and assume the private | |
570 | key is in the same file as the certificate. */ | |
571 | ||
572 | if (expanded != NULL && *expanded != 0) | |
573 | { | |
574 | DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded); | |
575 | if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM)) | |
576 | return tls_error(string_sprintf( | |
577 | "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL); | |
578 | } | |
579 | ||
3f7eeb86 PP |
580 | #ifdef EXPERIMENTAL_OCSP |
581 | if (cbinfo->ocsp_file != NULL) | |
582 | { | |
583 | if (!expand_check(cbinfo->ocsp_file, US"tls_ocsp_file", &expanded)) | |
584 | return DEFER; | |
585 | ||
586 | if (expanded != NULL && *expanded != 0) | |
587 | { | |
588 | DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded); | |
589 | if (cbinfo->ocsp_file_expanded && | |
590 | (Ustrcmp(expanded, cbinfo->ocsp_file_expanded) == 0)) | |
591 | { | |
592 | DEBUG(D_tls) | |
593 | debug_printf("tls_ocsp_file value unchanged, using existing values.\n"); | |
594 | } else { | |
595 | ocsp_load_response(sctx, cbinfo, expanded); | |
596 | } | |
597 | } | |
598 | } | |
599 | #endif | |
600 | ||
7be682ca PP |
601 | return OK; |
602 | } | |
603 | ||
604 | ||
605 | ||
606 | ||
607 | /************************************************* | |
608 | * Callback to handle SNI * | |
609 | *************************************************/ | |
610 | ||
611 | /* Called when acting as server during the TLS session setup if a Server Name | |
612 | Indication extension was sent by the client. | |
613 | ||
614 | API documentation is OpenSSL s_server.c implementation. | |
615 | ||
616 | Arguments: | |
617 | s SSL* of the current session | |
618 | ad unknown (part of OpenSSL API) (unused) | |
619 | arg Callback of "our" registered data | |
620 | ||
621 | Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK} | |
622 | */ | |
623 | ||
3bcbbbe2 | 624 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
7be682ca PP |
625 | static int |
626 | tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg) | |
627 | { | |
628 | const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name); | |
3f7eeb86 | 629 | tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg; |
7be682ca | 630 | int rc; |
3f0945ff | 631 | int old_pool = store_pool; |
7be682ca PP |
632 | |
633 | if (!servername) | |
634 | return SSL_TLSEXT_ERR_OK; | |
635 | ||
3f0945ff | 636 | DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername, |
7be682ca PP |
637 | reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)"); |
638 | ||
639 | /* Make the extension value available for expansion */ | |
3f0945ff | 640 | store_pool = POOL_PERM; |
817d9f57 | 641 | tls_in.sni = string_copy(US servername); |
3f0945ff | 642 | store_pool = old_pool; |
7be682ca PP |
643 | |
644 | if (!reexpand_tls_files_for_sni) | |
645 | return SSL_TLSEXT_ERR_OK; | |
646 | ||
647 | /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually; | |
648 | not confident that memcpy wouldn't break some internal reference counting. | |
649 | Especially since there's a references struct member, which would be off. */ | |
650 | ||
817d9f57 JH |
651 | server_sni = SSL_CTX_new(SSLv23_server_method()); |
652 | if (!server_sni) | |
7be682ca PP |
653 | { |
654 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
655 | DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring); | |
656 | return SSL_TLSEXT_ERR_NOACK; | |
657 | } | |
658 | ||
659 | /* Not sure how many of these are actually needed, since SSL object | |
660 | already exists. Might even need this selfsame callback, for reneg? */ | |
661 | ||
817d9f57 JH |
662 | SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx)); |
663 | SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx)); | |
664 | SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx)); | |
665 | SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx)); | |
666 | SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb); | |
667 | SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo); | |
7be682ca | 668 | if (cbinfo->server_cipher_list) |
817d9f57 | 669 | SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list); |
3f7eeb86 PP |
670 | #ifdef EXPERIMENTAL_OCSP |
671 | if (cbinfo->ocsp_file) | |
672 | { | |
817d9f57 | 673 | SSL_CTX_set_tlsext_status_cb(server_sni, tls_stapling_cb); |
3f7eeb86 PP |
674 | SSL_CTX_set_tlsext_status_arg(ctx, cbinfo); |
675 | } | |
676 | #endif | |
7be682ca | 677 | |
a2ff477a | 678 | rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, FALSE); |
7be682ca PP |
679 | if (rc != OK) return SSL_TLSEXT_ERR_NOACK; |
680 | ||
3f7eeb86 PP |
681 | /* do this after setup_certs, because this can require the certs for verifying |
682 | OCSP information. */ | |
817d9f57 | 683 | rc = tls_expand_session_files(server_sni, cbinfo); |
7be682ca PP |
684 | if (rc != OK) return SSL_TLSEXT_ERR_NOACK; |
685 | ||
389ca47a | 686 | rc = init_dh(server_sni, cbinfo->dhparam, NULL); |
a799883d PP |
687 | if (rc != OK) return SSL_TLSEXT_ERR_NOACK; |
688 | ||
7be682ca | 689 | DEBUG(D_tls) debug_printf("Switching SSL context.\n"); |
817d9f57 | 690 | SSL_set_SSL_CTX(s, server_sni); |
7be682ca PP |
691 | |
692 | return SSL_TLSEXT_ERR_OK; | |
693 | } | |
3bcbbbe2 | 694 | #endif /* EXIM_HAVE_OPENSSL_TLSEXT */ |
7be682ca PP |
695 | |
696 | ||
697 | ||
698 | ||
3f7eeb86 PP |
699 | #ifdef EXPERIMENTAL_OCSP |
700 | /************************************************* | |
701 | * Callback to handle OCSP Stapling * | |
702 | *************************************************/ | |
703 | ||
704 | /* Called when acting as server during the TLS session setup if the client | |
705 | requests OCSP information with a Certificate Status Request. | |
706 | ||
707 | Documentation via openssl s_server.c and the Apache patch from the OpenSSL | |
708 | project. | |
709 | ||
710 | */ | |
711 | ||
712 | static int | |
713 | tls_stapling_cb(SSL *s, void *arg) | |
714 | { | |
715 | const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg; | |
716 | uschar *response_der; | |
717 | int response_der_len; | |
718 | ||
719 | DEBUG(D_tls) debug_printf("Received TLS status request (OCSP stapling); %s response.\n", | |
720 | cbinfo->ocsp_response ? "have" : "lack"); | |
721 | if (!cbinfo->ocsp_response) | |
722 | return SSL_TLSEXT_ERR_NOACK; | |
723 | ||
724 | response_der = NULL; | |
725 | response_der_len = i2d_OCSP_RESPONSE(cbinfo->ocsp_response, &response_der); | |
726 | if (response_der_len <= 0) | |
727 | return SSL_TLSEXT_ERR_NOACK; | |
728 | ||
729 | SSL_set_tlsext_status_ocsp_resp(ssl, response_der, response_der_len); | |
730 | return SSL_TLSEXT_ERR_OK; | |
731 | } | |
732 | ||
733 | #endif /* EXPERIMENTAL_OCSP */ | |
734 | ||
735 | ||
736 | ||
737 | ||
059ec3d9 PH |
738 | /************************************************* |
739 | * Initialize for TLS * | |
740 | *************************************************/ | |
741 | ||
742 | /* Called from both server and client code, to do preliminary initialization of | |
743 | the library. | |
744 | ||
745 | Arguments: | |
746 | host connected host, if client; NULL if server | |
747 | dhparam DH parameter file | |
748 | certificate certificate file | |
749 | privatekey private key | |
750 | addr address if client; NULL if server (for some randomness) | |
751 | ||
752 | Returns: OK/DEFER/FAIL | |
753 | */ | |
754 | ||
755 | static int | |
817d9f57 | 756 | tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate, |
3f7eeb86 PP |
757 | uschar *privatekey, |
758 | #ifdef EXPERIMENTAL_OCSP | |
759 | uschar *ocsp_file, | |
760 | #endif | |
817d9f57 | 761 | address_item *addr, tls_ext_ctx_cb ** cbp) |
059ec3d9 | 762 | { |
77bb000f | 763 | long init_options; |
7be682ca | 764 | int rc; |
77bb000f | 765 | BOOL okay; |
7be682ca PP |
766 | tls_ext_ctx_cb *cbinfo; |
767 | ||
768 | cbinfo = store_malloc(sizeof(tls_ext_ctx_cb)); | |
769 | cbinfo->certificate = certificate; | |
770 | cbinfo->privatekey = privatekey; | |
3f7eeb86 PP |
771 | #ifdef EXPERIMENTAL_OCSP |
772 | cbinfo->ocsp_file = ocsp_file; | |
773 | #endif | |
7be682ca PP |
774 | cbinfo->dhparam = dhparam; |
775 | cbinfo->host = host; | |
77bb000f | 776 | |
059ec3d9 PH |
777 | SSL_load_error_strings(); /* basic set up */ |
778 | OpenSSL_add_ssl_algorithms(); | |
779 | ||
388d6564 | 780 | #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256) |
77bb000f | 781 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the |
a0475b69 TK |
782 | list of available digests. */ |
783 | EVP_add_digest(EVP_sha256()); | |
cf1ef1a9 | 784 | #endif |
a0475b69 | 785 | |
f0f5a555 PP |
786 | /* Create a context. |
787 | The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant | |
788 | negotiation in the different methods; as far as I can tell, the only | |
789 | *_{server,client}_method which allows negotiation is SSLv23, which exists even | |
790 | when OpenSSL is built without SSLv2 support. | |
791 | By disabling with openssl_options, we can let admins re-enable with the | |
792 | existing knob. */ | |
059ec3d9 | 793 | |
817d9f57 | 794 | *ctxp = SSL_CTX_new((host == NULL)? |
059ec3d9 PH |
795 | SSLv23_server_method() : SSLv23_client_method()); |
796 | ||
817d9f57 | 797 | if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL); |
059ec3d9 PH |
798 | |
799 | /* It turns out that we need to seed the random number generator this early in | |
800 | order to get the full complement of ciphers to work. It took me roughly a day | |
801 | of work to discover this by experiment. | |
802 | ||
803 | On systems that have /dev/urandom, SSL may automatically seed itself from | |
804 | there. Otherwise, we have to make something up as best we can. Double check | |
805 | afterwards. */ | |
806 | ||
807 | if (!RAND_status()) | |
808 | { | |
809 | randstuff r; | |
9e3331ea | 810 | gettimeofday(&r.tv, NULL); |
059ec3d9 PH |
811 | r.p = getpid(); |
812 | ||
813 | RAND_seed((uschar *)(&r), sizeof(r)); | |
814 | RAND_seed((uschar *)big_buffer, big_buffer_size); | |
815 | if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr)); | |
816 | ||
817 | if (!RAND_status()) | |
7199e1ee | 818 | return tls_error(US"RAND_status", host, |
5ca6d115 | 819 | US"unable to seed random number generator"); |
059ec3d9 PH |
820 | } |
821 | ||
822 | /* Set up the information callback, which outputs if debugging is at a suitable | |
823 | level. */ | |
824 | ||
817d9f57 | 825 | SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback); |
059ec3d9 | 826 | |
c80c5570 | 827 | /* Automatically re-try reads/writes after renegotiation. */ |
817d9f57 | 828 | (void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY); |
c80c5570 | 829 | |
77bb000f PP |
830 | /* Apply administrator-supplied work-arounds. |
831 | Historically we applied just one requested option, | |
832 | SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we | |
833 | moved to an administrator-controlled list of options to specify and | |
834 | grandfathered in the first one as the default value for "openssl_options". | |
059ec3d9 | 835 | |
77bb000f PP |
836 | No OpenSSL version number checks: the options we accept depend upon the |
837 | availability of the option value macros from OpenSSL. */ | |
059ec3d9 | 838 | |
77bb000f PP |
839 | okay = tls_openssl_options_parse(openssl_options, &init_options); |
840 | if (!okay) | |
73a46702 | 841 | return tls_error(US"openssl_options parsing failed", host, NULL); |
77bb000f PP |
842 | |
843 | if (init_options) | |
844 | { | |
845 | DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options); | |
817d9f57 | 846 | if (!(SSL_CTX_set_options(*ctxp, init_options))) |
77bb000f PP |
847 | return tls_error(string_sprintf( |
848 | "SSL_CTX_set_option(%#lx)", init_options), host, NULL); | |
849 | } | |
850 | else | |
851 | DEBUG(D_tls) debug_printf("no SSL CTX options to set\n"); | |
059ec3d9 PH |
852 | |
853 | /* Initialize with DH parameters if supplied */ | |
854 | ||
817d9f57 | 855 | if (!init_dh(*ctxp, dhparam, host)) return DEFER; |
059ec3d9 | 856 | |
3f7eeb86 | 857 | /* Set up certificate and key (and perhaps OCSP info) */ |
059ec3d9 | 858 | |
817d9f57 | 859 | rc = tls_expand_session_files(*ctxp, cbinfo); |
7be682ca | 860 | if (rc != OK) return rc; |
c91535f3 | 861 | |
7be682ca | 862 | /* If we need to handle SNI, do so */ |
3bcbbbe2 | 863 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
3f0945ff PP |
864 | if (host == NULL) |
865 | { | |
3f7eeb86 PP |
866 | #ifdef EXPERIMENTAL_OCSP |
867 | /* We check ocsp_file, not ocsp_response, because we care about if | |
868 | the option exists, not what the current expansion might be, as SNI might | |
869 | change the certificate and OCSP file in use between now and the time the | |
870 | callback is invoked. */ | |
871 | if (cbinfo->ocsp_file) | |
872 | { | |
873 | SSL_CTX_set_tlsext_status_cb(ctx, tls_stapling_cb); | |
874 | SSL_CTX_set_tlsext_status_arg(ctx, cbinfo); | |
875 | } | |
876 | #endif | |
3f0945ff PP |
877 | /* We always do this, so that $tls_sni is available even if not used in |
878 | tls_certificate */ | |
817d9f57 JH |
879 | SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb); |
880 | SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo); | |
3f0945ff | 881 | } |
7be682ca | 882 | #endif |
059ec3d9 PH |
883 | |
884 | /* Set up the RSA callback */ | |
885 | ||
817d9f57 | 886 | SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback); |
059ec3d9 PH |
887 | |
888 | /* Finally, set the timeout, and we are done */ | |
889 | ||
817d9f57 | 890 | SSL_CTX_set_timeout(*ctxp, ssl_session_timeout); |
059ec3d9 | 891 | DEBUG(D_tls) debug_printf("Initialized TLS\n"); |
7be682ca | 892 | |
817d9f57 | 893 | *cbp = cbinfo; |
7be682ca | 894 | |
059ec3d9 PH |
895 | return OK; |
896 | } | |
897 | ||
898 | ||
899 | ||
900 | ||
901 | /************************************************* | |
902 | * Get name of cipher in use * | |
903 | *************************************************/ | |
904 | ||
817d9f57 | 905 | /* |
059ec3d9 | 906 | Argument: pointer to an SSL structure for the connection |
817d9f57 JH |
907 | buffer to use for answer |
908 | size of buffer | |
909 | pointer to number of bits for cipher | |
059ec3d9 PH |
910 | Returns: nothing |
911 | */ | |
912 | ||
913 | static void | |
817d9f57 | 914 | construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits) |
059ec3d9 | 915 | { |
57b3a7f5 PP |
916 | /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't |
917 | yet reflect that. It should be a safe change anyway, even 0.9.8 versions have | |
918 | the accessor functions use const in the prototype. */ | |
919 | const SSL_CIPHER *c; | |
059ec3d9 | 920 | uschar *ver; |
059ec3d9 PH |
921 | |
922 | switch (ssl->session->ssl_version) | |
923 | { | |
924 | case SSL2_VERSION: | |
925 | ver = US"SSLv2"; | |
926 | break; | |
927 | ||
928 | case SSL3_VERSION: | |
929 | ver = US"SSLv3"; | |
930 | break; | |
931 | ||
932 | case TLS1_VERSION: | |
933 | ver = US"TLSv1"; | |
934 | break; | |
935 | ||
c80c5570 PP |
936 | #ifdef TLS1_1_VERSION |
937 | case TLS1_1_VERSION: | |
938 | ver = US"TLSv1.1"; | |
939 | break; | |
940 | #endif | |
941 | ||
942 | #ifdef TLS1_2_VERSION | |
943 | case TLS1_2_VERSION: | |
944 | ver = US"TLSv1.2"; | |
945 | break; | |
946 | #endif | |
947 | ||
059ec3d9 PH |
948 | default: |
949 | ver = US"UNKNOWN"; | |
950 | } | |
951 | ||
57b3a7f5 | 952 | c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl); |
817d9f57 | 953 | SSL_CIPHER_get_bits(c, bits); |
059ec3d9 | 954 | |
817d9f57 JH |
955 | string_format(cipherbuf, bsize, "%s:%s:%u", ver, |
956 | SSL_CIPHER_get_name(c), *bits); | |
059ec3d9 PH |
957 | |
958 | DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf); | |
959 | } | |
960 | ||
961 | ||
962 | ||
963 | ||
964 | ||
965 | /************************************************* | |
966 | * Set up for verifying certificates * | |
967 | *************************************************/ | |
968 | ||
969 | /* Called by both client and server startup | |
970 | ||
971 | Arguments: | |
7be682ca | 972 | sctx SSL_CTX* to initialise |
059ec3d9 PH |
973 | certs certs file or NULL |
974 | crl CRL file or NULL | |
975 | host NULL in a server; the remote host in a client | |
976 | optional TRUE if called from a server for a host in tls_try_verify_hosts; | |
977 | otherwise passed as FALSE | |
a2ff477a | 978 | client TRUE if called for client startup, FALSE for server startup |
059ec3d9 PH |
979 | |
980 | Returns: OK/DEFER/FAIL | |
981 | */ | |
982 | ||
983 | static int | |
a2ff477a | 984 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional, BOOL client) |
059ec3d9 PH |
985 | { |
986 | uschar *expcerts, *expcrl; | |
987 | ||
988 | if (!expand_check(certs, US"tls_verify_certificates", &expcerts)) | |
989 | return DEFER; | |
990 | ||
991 | if (expcerts != NULL) | |
992 | { | |
993 | struct stat statbuf; | |
7be682ca | 994 | if (!SSL_CTX_set_default_verify_paths(sctx)) |
7199e1ee | 995 | return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL); |
059ec3d9 PH |
996 | |
997 | if (Ustat(expcerts, &statbuf) < 0) | |
998 | { | |
999 | log_write(0, LOG_MAIN|LOG_PANIC, | |
1000 | "failed to stat %s for certificates", expcerts); | |
1001 | return DEFER; | |
1002 | } | |
1003 | else | |
1004 | { | |
1005 | uschar *file, *dir; | |
1006 | if ((statbuf.st_mode & S_IFMT) == S_IFDIR) | |
1007 | { file = NULL; dir = expcerts; } | |
1008 | else | |
1009 | { file = expcerts; dir = NULL; } | |
1010 | ||
1011 | /* If a certificate file is empty, the next function fails with an | |
1012 | unhelpful error message. If we skip it, we get the correct behaviour (no | |
1013 | certificates are recognized, but the error message is still misleading (it | |
1014 | says no certificate was supplied.) But this is better. */ | |
1015 | ||
1016 | if ((file == NULL || statbuf.st_size > 0) && | |
7be682ca | 1017 | !SSL_CTX_load_verify_locations(sctx, CS file, CS dir)) |
7199e1ee | 1018 | return tls_error(US"SSL_CTX_load_verify_locations", host, NULL); |
059ec3d9 PH |
1019 | |
1020 | if (file != NULL) | |
1021 | { | |
7be682ca | 1022 | SSL_CTX_set_client_CA_list(sctx, SSL_load_client_CA_file(CS file)); |
059ec3d9 PH |
1023 | } |
1024 | } | |
1025 | ||
1026 | /* Handle a certificate revocation list. */ | |
1027 | ||
1028 | #if OPENSSL_VERSION_NUMBER > 0x00907000L | |
1029 | ||
8b417f2c PH |
1030 | /* This bit of code is now the version supplied by Lars Mainka. (I have |
1031 | * merely reformatted it into the Exim code style.) | |
1032 | ||
1033 | * "From here I changed the code to add support for multiple crl's | |
1034 | * in pem format in one file or to support hashed directory entries in | |
1035 | * pem format instead of a file. This method now uses the library function | |
1036 | * X509_STORE_load_locations to add the CRL location to the SSL context. | |
1037 | * OpenSSL will then handle the verify against CA certs and CRLs by | |
1038 | * itself in the verify callback." */ | |
1039 | ||
059ec3d9 PH |
1040 | if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER; |
1041 | if (expcrl != NULL && *expcrl != 0) | |
1042 | { | |
8b417f2c PH |
1043 | struct stat statbufcrl; |
1044 | if (Ustat(expcrl, &statbufcrl) < 0) | |
1045 | { | |
1046 | log_write(0, LOG_MAIN|LOG_PANIC, | |
1047 | "failed to stat %s for certificates revocation lists", expcrl); | |
1048 | return DEFER; | |
1049 | } | |
1050 | else | |
059ec3d9 | 1051 | { |
8b417f2c PH |
1052 | /* is it a file or directory? */ |
1053 | uschar *file, *dir; | |
7be682ca | 1054 | X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx); |
8b417f2c | 1055 | if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR) |
059ec3d9 | 1056 | { |
8b417f2c PH |
1057 | file = NULL; |
1058 | dir = expcrl; | |
1059 | DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir); | |
059ec3d9 PH |
1060 | } |
1061 | else | |
1062 | { | |
8b417f2c PH |
1063 | file = expcrl; |
1064 | dir = NULL; | |
1065 | DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file); | |
059ec3d9 | 1066 | } |
8b417f2c | 1067 | if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0) |
7199e1ee | 1068 | return tls_error(US"X509_STORE_load_locations", host, NULL); |
8b417f2c PH |
1069 | |
1070 | /* setting the flags to check against the complete crl chain */ | |
1071 | ||
1072 | X509_STORE_set_flags(cvstore, | |
1073 | X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL); | |
059ec3d9 | 1074 | } |
059ec3d9 PH |
1075 | } |
1076 | ||
1077 | #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */ | |
1078 | ||
1079 | /* If verification is optional, don't fail if no certificate */ | |
1080 | ||
7be682ca | 1081 | SSL_CTX_set_verify(sctx, |
059ec3d9 | 1082 | SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT), |
a2ff477a | 1083 | client ? verify_callback_client : verify_callback_server); |
059ec3d9 PH |
1084 | } |
1085 | ||
1086 | return OK; | |
1087 | } | |
1088 | ||
1089 | ||
1090 | ||
1091 | /************************************************* | |
1092 | * Start a TLS session in a server * | |
1093 | *************************************************/ | |
1094 | ||
1095 | /* This is called when Exim is running as a server, after having received | |
1096 | the STARTTLS command. It must respond to that command, and then negotiate | |
1097 | a TLS session. | |
1098 | ||
1099 | Arguments: | |
1100 | require_ciphers allowed ciphers | |
1101 | ||
1102 | Returns: OK on success | |
1103 | DEFER for errors before the start of the negotiation | |
1104 | FAIL for errors during the negotation; the server can't | |
1105 | continue running. | |
1106 | */ | |
1107 | ||
1108 | int | |
17c76198 | 1109 | tls_server_start(const uschar *require_ciphers) |
059ec3d9 PH |
1110 | { |
1111 | int rc; | |
1112 | uschar *expciphers; | |
7be682ca | 1113 | tls_ext_ctx_cb *cbinfo; |
817d9f57 | 1114 | static uschar cipherbuf[256]; |
059ec3d9 PH |
1115 | |
1116 | /* Check for previous activation */ | |
1117 | ||
817d9f57 | 1118 | if (tls_in.active >= 0) |
059ec3d9 | 1119 | { |
5ca6d115 | 1120 | tls_error(US"STARTTLS received after TLS started", NULL, US""); |
059ec3d9 PH |
1121 | smtp_printf("554 Already in TLS\r\n"); |
1122 | return FAIL; | |
1123 | } | |
1124 | ||
1125 | /* Initialize the SSL library. If it fails, it will already have logged | |
1126 | the error. */ | |
1127 | ||
817d9f57 | 1128 | rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey, |
3f7eeb86 PP |
1129 | #ifdef EXPERIMENTAL_OCSP |
1130 | tls_ocsp_file, | |
1131 | #endif | |
817d9f57 | 1132 | NULL, &server_static_cbinfo); |
059ec3d9 | 1133 | if (rc != OK) return rc; |
817d9f57 | 1134 | cbinfo = server_static_cbinfo; |
059ec3d9 PH |
1135 | |
1136 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers)) | |
1137 | return FAIL; | |
1138 | ||
1139 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they | |
17c76198 PP |
1140 | were historically separated by underscores. So that I can use either form in my |
1141 | tests, and also for general convenience, we turn underscores into hyphens here. | |
1142 | */ | |
059ec3d9 PH |
1143 | |
1144 | if (expciphers != NULL) | |
1145 | { | |
1146 | uschar *s = expciphers; | |
1147 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } | |
1148 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); | |
817d9f57 | 1149 | if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers)) |
7199e1ee | 1150 | return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL); |
7be682ca | 1151 | cbinfo->server_cipher_list = expciphers; |
059ec3d9 PH |
1152 | } |
1153 | ||
1154 | /* If this is a host for which certificate verification is mandatory or | |
1155 | optional, set up appropriately. */ | |
1156 | ||
817d9f57 | 1157 | tls_in.certificate_verified = FALSE; |
a2ff477a | 1158 | server_verify_callback_called = FALSE; |
059ec3d9 PH |
1159 | |
1160 | if (verify_check_host(&tls_verify_hosts) == OK) | |
1161 | { | |
a2ff477a | 1162 | rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL, FALSE, FALSE); |
059ec3d9 | 1163 | if (rc != OK) return rc; |
a2ff477a | 1164 | server_verify_optional = FALSE; |
059ec3d9 PH |
1165 | } |
1166 | else if (verify_check_host(&tls_try_verify_hosts) == OK) | |
1167 | { | |
a2ff477a | 1168 | rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL, TRUE, FALSE); |
059ec3d9 | 1169 | if (rc != OK) return rc; |
a2ff477a | 1170 | server_verify_optional = TRUE; |
059ec3d9 PH |
1171 | } |
1172 | ||
1173 | /* Prepare for new connection */ | |
1174 | ||
817d9f57 | 1175 | if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL); |
da3ad30d PP |
1176 | |
1177 | /* Warning: we used to SSL_clear(ssl) here, it was removed. | |
1178 | * | |
1179 | * With the SSL_clear(), we get strange interoperability bugs with | |
1180 | * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in | |
1181 | * OpenSSL itself, as a clear should not lead to inability to follow protocols. | |
1182 | * | |
1183 | * The SSL_clear() call is to let an existing SSL* be reused, typically after | |
1184 | * session shutdown. In this case, we have a brand new object and there's no | |
1185 | * obvious reason to immediately clear it. I'm guessing that this was | |
1186 | * originally added because of incomplete initialisation which the clear fixed, | |
1187 | * in some historic release. | |
1188 | */ | |
059ec3d9 PH |
1189 | |
1190 | /* Set context and tell client to go ahead, except in the case of TLS startup | |
1191 | on connection, where outputting anything now upsets the clients and tends to | |
1192 | make them disconnect. We need to have an explicit fflush() here, to force out | |
1193 | the response. Other smtp_printf() calls do not need it, because in non-TLS | |
1194 | mode, the fflush() happens when smtp_getc() is called. */ | |
1195 | ||
817d9f57 JH |
1196 | SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx)); |
1197 | if (!tls_in.on_connect) | |
059ec3d9 PH |
1198 | { |
1199 | smtp_printf("220 TLS go ahead\r\n"); | |
1200 | fflush(smtp_out); | |
1201 | } | |
1202 | ||
1203 | /* Now negotiate the TLS session. We put our own timer on it, since it seems | |
1204 | that the OpenSSL library doesn't. */ | |
1205 | ||
817d9f57 JH |
1206 | SSL_set_wfd(server_ssl, fileno(smtp_out)); |
1207 | SSL_set_rfd(server_ssl, fileno(smtp_in)); | |
1208 | SSL_set_accept_state(server_ssl); | |
059ec3d9 PH |
1209 | |
1210 | DEBUG(D_tls) debug_printf("Calling SSL_accept\n"); | |
1211 | ||
1212 | sigalrm_seen = FALSE; | |
1213 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
817d9f57 | 1214 | rc = SSL_accept(server_ssl); |
059ec3d9 PH |
1215 | alarm(0); |
1216 | ||
1217 | if (rc <= 0) | |
1218 | { | |
7199e1ee | 1219 | tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL); |
77bb000f PP |
1220 | if (ERR_get_error() == 0) |
1221 | log_write(0, LOG_MAIN, | |
a053d125 | 1222 | "TLS client disconnected cleanly (rejected our certificate?)"); |
059ec3d9 PH |
1223 | return FAIL; |
1224 | } | |
1225 | ||
1226 | DEBUG(D_tls) debug_printf("SSL_accept was successful\n"); | |
1227 | ||
1228 | /* TLS has been set up. Adjust the input functions to read via TLS, | |
1229 | and initialize things. */ | |
1230 | ||
817d9f57 JH |
1231 | construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits); |
1232 | tls_in.cipher = cipherbuf; | |
059ec3d9 PH |
1233 | |
1234 | DEBUG(D_tls) | |
1235 | { | |
1236 | uschar buf[2048]; | |
817d9f57 | 1237 | if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL) |
059ec3d9 PH |
1238 | debug_printf("Shared ciphers: %s\n", buf); |
1239 | } | |
1240 | ||
1241 | ||
817d9f57 JH |
1242 | /* Only used by the server-side tls (tls_in), including tls_getc. |
1243 | Client-side (tls_out) reads (seem to?) go via | |
1244 | smtp_read_response()/ip_recv(). | |
1245 | Hence no need to duplicate for _in and _out. | |
1246 | */ | |
059ec3d9 PH |
1247 | ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size); |
1248 | ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0; | |
1249 | ssl_xfer_eof = ssl_xfer_error = 0; | |
1250 | ||
1251 | receive_getc = tls_getc; | |
1252 | receive_ungetc = tls_ungetc; | |
1253 | receive_feof = tls_feof; | |
1254 | receive_ferror = tls_ferror; | |
58eb016e | 1255 | receive_smtp_buffered = tls_smtp_buffered; |
059ec3d9 | 1256 | |
817d9f57 | 1257 | tls_in.active = fileno(smtp_out); |
059ec3d9 PH |
1258 | return OK; |
1259 | } | |
1260 | ||
1261 | ||
1262 | ||
1263 | ||
1264 | ||
1265 | /************************************************* | |
1266 | * Start a TLS session in a client * | |
1267 | *************************************************/ | |
1268 | ||
1269 | /* Called from the smtp transport after STARTTLS has been accepted. | |
1270 | ||
1271 | Argument: | |
1272 | fd the fd of the connection | |
1273 | host connected host (for messages) | |
83da1223 | 1274 | addr the first address |
059ec3d9 PH |
1275 | dhparam DH parameter file |
1276 | certificate certificate file | |
1277 | privatekey private key file | |
3f0945ff | 1278 | sni TLS SNI to send to remote host |
059ec3d9 PH |
1279 | verify_certs file for certificate verify |
1280 | crl file containing CRL | |
1281 | require_ciphers list of allowed ciphers | |
54c90be1 PP |
1282 | dh_min_bits minimum number of bits acceptable in server's DH prime |
1283 | (unused in OpenSSL) | |
83da1223 | 1284 | timeout startup timeout |
059ec3d9 PH |
1285 | |
1286 | Returns: OK on success | |
1287 | FAIL otherwise - note that tls_error() will not give DEFER | |
1288 | because this is not a server | |
1289 | */ | |
1290 | ||
1291 | int | |
1292 | tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam, | |
3f0945ff PP |
1293 | uschar *certificate, uschar *privatekey, uschar *sni, |
1294 | uschar *verify_certs, uschar *crl, | |
54c90be1 | 1295 | uschar *require_ciphers, int dh_min_bits ARG_UNUSED, int timeout) |
059ec3d9 PH |
1296 | { |
1297 | static uschar txt[256]; | |
1298 | uschar *expciphers; | |
1299 | X509* server_cert; | |
1300 | int rc; | |
817d9f57 | 1301 | static uschar cipherbuf[256]; |
059ec3d9 | 1302 | |
817d9f57 | 1303 | rc = tls_init(&client_ctx, host, dhparam, certificate, privatekey, |
3f7eeb86 PP |
1304 | #ifdef EXPERIMENTAL_OCSP |
1305 | NULL, | |
1306 | #endif | |
817d9f57 | 1307 | addr, &client_static_cbinfo); |
059ec3d9 PH |
1308 | if (rc != OK) return rc; |
1309 | ||
817d9f57 | 1310 | tls_out.certificate_verified = FALSE; |
a2ff477a | 1311 | client_verify_callback_called = FALSE; |
059ec3d9 PH |
1312 | |
1313 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers)) | |
1314 | return FAIL; | |
1315 | ||
1316 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they | |
1317 | are separated by underscores. So that I can use either form in my tests, and | |
1318 | also for general convenience, we turn underscores into hyphens here. */ | |
1319 | ||
1320 | if (expciphers != NULL) | |
1321 | { | |
1322 | uschar *s = expciphers; | |
1323 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } | |
1324 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); | |
817d9f57 | 1325 | if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers)) |
7199e1ee | 1326 | return tls_error(US"SSL_CTX_set_cipher_list", host, NULL); |
059ec3d9 PH |
1327 | } |
1328 | ||
a2ff477a | 1329 | rc = setup_certs(client_ctx, verify_certs, crl, host, FALSE, TRUE); |
059ec3d9 PH |
1330 | if (rc != OK) return rc; |
1331 | ||
817d9f57 JH |
1332 | if ((client_ssl = SSL_new(client_ctx)) == NULL) return tls_error(US"SSL_new", host, NULL); |
1333 | SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx)); | |
1334 | SSL_set_fd(client_ssl, fd); | |
1335 | SSL_set_connect_state(client_ssl); | |
059ec3d9 | 1336 | |
3f0945ff PP |
1337 | if (sni) |
1338 | { | |
817d9f57 | 1339 | if (!expand_check(sni, US"tls_sni", &tls_out.sni)) |
3f0945ff | 1340 | return FAIL; |
817d9f57 JH |
1341 | if (!Ustrlen(tls_out.sni)) |
1342 | tls_out.sni = NULL; | |
3f0945ff PP |
1343 | else |
1344 | { | |
35731706 | 1345 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
817d9f57 JH |
1346 | DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni); |
1347 | SSL_set_tlsext_host_name(client_ssl, tls_out.sni); | |
35731706 PP |
1348 | #else |
1349 | DEBUG(D_tls) | |
1350 | debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n", | |
1351 | tls_sni); | |
1352 | #endif | |
3f0945ff PP |
1353 | } |
1354 | } | |
1355 | ||
059ec3d9 PH |
1356 | /* There doesn't seem to be a built-in timeout on connection. */ |
1357 | ||
1358 | DEBUG(D_tls) debug_printf("Calling SSL_connect\n"); | |
1359 | sigalrm_seen = FALSE; | |
1360 | alarm(timeout); | |
817d9f57 | 1361 | rc = SSL_connect(client_ssl); |
059ec3d9 PH |
1362 | alarm(0); |
1363 | ||
1364 | if (rc <= 0) | |
7199e1ee | 1365 | return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL); |
059ec3d9 PH |
1366 | |
1367 | DEBUG(D_tls) debug_printf("SSL_connect succeeded\n"); | |
1368 | ||
453a6645 | 1369 | /* Beware anonymous ciphers which lead to server_cert being NULL */ |
817d9f57 | 1370 | server_cert = SSL_get_peer_certificate (client_ssl); |
453a6645 PP |
1371 | if (server_cert) |
1372 | { | |
817d9f57 | 1373 | tls_out.peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert), |
453a6645 | 1374 | CS txt, sizeof(txt)); |
817d9f57 | 1375 | tls_out.peerdn = txt; |
453a6645 PP |
1376 | } |
1377 | else | |
817d9f57 | 1378 | tls_out.peerdn = NULL; |
059ec3d9 | 1379 | |
817d9f57 JH |
1380 | construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits); |
1381 | tls_out.cipher = cipherbuf; | |
059ec3d9 | 1382 | |
817d9f57 | 1383 | tls_out.active = fd; |
059ec3d9 PH |
1384 | return OK; |
1385 | } | |
1386 | ||
1387 | ||
1388 | ||
1389 | ||
1390 | ||
1391 | /************************************************* | |
1392 | * TLS version of getc * | |
1393 | *************************************************/ | |
1394 | ||
1395 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, | |
1396 | it refills the buffer via the SSL reading function. | |
1397 | ||
1398 | Arguments: none | |
1399 | Returns: the next character or EOF | |
817d9f57 JH |
1400 | |
1401 | Only used by the server-side TLS. | |
059ec3d9 PH |
1402 | */ |
1403 | ||
1404 | int | |
1405 | tls_getc(void) | |
1406 | { | |
1407 | if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm) | |
1408 | { | |
1409 | int error; | |
1410 | int inbytes; | |
1411 | ||
817d9f57 | 1412 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl, |
c80c5570 | 1413 | ssl_xfer_buffer, ssl_xfer_buffer_size); |
059ec3d9 PH |
1414 | |
1415 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
817d9f57 JH |
1416 | inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size); |
1417 | error = SSL_get_error(server_ssl, inbytes); | |
059ec3d9 PH |
1418 | alarm(0); |
1419 | ||
1420 | /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been | |
1421 | closed down, not that the socket itself has been closed down. Revert to | |
1422 | non-SSL handling. */ | |
1423 | ||
1424 | if (error == SSL_ERROR_ZERO_RETURN) | |
1425 | { | |
1426 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); | |
1427 | ||
1428 | receive_getc = smtp_getc; | |
1429 | receive_ungetc = smtp_ungetc; | |
1430 | receive_feof = smtp_feof; | |
1431 | receive_ferror = smtp_ferror; | |
58eb016e | 1432 | receive_smtp_buffered = smtp_buffered; |
059ec3d9 | 1433 | |
817d9f57 JH |
1434 | SSL_free(server_ssl); |
1435 | server_ssl = NULL; | |
1436 | tls_in.active = -1; | |
1437 | tls_in.bits = 0; | |
1438 | tls_in.cipher = NULL; | |
1439 | tls_in.peerdn = NULL; | |
1440 | tls_in.sni = NULL; | |
059ec3d9 PH |
1441 | |
1442 | return smtp_getc(); | |
1443 | } | |
1444 | ||
1445 | /* Handle genuine errors */ | |
1446 | ||
ba084640 PP |
1447 | else if (error == SSL_ERROR_SSL) |
1448 | { | |
1449 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
89dd51cd | 1450 | log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring); |
ba084640 PP |
1451 | ssl_xfer_error = 1; |
1452 | return EOF; | |
1453 | } | |
1454 | ||
059ec3d9 PH |
1455 | else if (error != SSL_ERROR_NONE) |
1456 | { | |
1457 | DEBUG(D_tls) debug_printf("Got SSL error %d\n", error); | |
1458 | ssl_xfer_error = 1; | |
1459 | return EOF; | |
1460 | } | |
c80c5570 | 1461 | |
80a47a2c TK |
1462 | #ifndef DISABLE_DKIM |
1463 | dkim_exim_verify_feed(ssl_xfer_buffer, inbytes); | |
1464 | #endif | |
059ec3d9 PH |
1465 | ssl_xfer_buffer_hwm = inbytes; |
1466 | ssl_xfer_buffer_lwm = 0; | |
1467 | } | |
1468 | ||
1469 | /* Something in the buffer; return next uschar */ | |
1470 | ||
1471 | return ssl_xfer_buffer[ssl_xfer_buffer_lwm++]; | |
1472 | } | |
1473 | ||
1474 | ||
1475 | ||
1476 | /************************************************* | |
1477 | * Read bytes from TLS channel * | |
1478 | *************************************************/ | |
1479 | ||
1480 | /* | |
1481 | Arguments: | |
1482 | buff buffer of data | |
1483 | len size of buffer | |
1484 | ||
1485 | Returns: the number of bytes read | |
1486 | -1 after a failed read | |
817d9f57 JH |
1487 | |
1488 | Only used by the client-side TLS. | |
059ec3d9 PH |
1489 | */ |
1490 | ||
1491 | int | |
389ca47a | 1492 | tls_read(BOOL is_server, uschar *buff, size_t len) |
059ec3d9 | 1493 | { |
389ca47a | 1494 | SSL *ssl = is_server ? server_ssl : client_ssl; |
059ec3d9 PH |
1495 | int inbytes; |
1496 | int error; | |
1497 | ||
389ca47a | 1498 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl, |
c80c5570 | 1499 | buff, (unsigned int)len); |
059ec3d9 | 1500 | |
389ca47a JH |
1501 | inbytes = SSL_read(ssl, CS buff, len); |
1502 | error = SSL_get_error(ssl, inbytes); | |
059ec3d9 PH |
1503 | |
1504 | if (error == SSL_ERROR_ZERO_RETURN) | |
1505 | { | |
1506 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); | |
1507 | return -1; | |
1508 | } | |
1509 | else if (error != SSL_ERROR_NONE) | |
1510 | { | |
1511 | return -1; | |
1512 | } | |
1513 | ||
1514 | return inbytes; | |
1515 | } | |
1516 | ||
1517 | ||
1518 | ||
1519 | ||
1520 | ||
1521 | /************************************************* | |
1522 | * Write bytes down TLS channel * | |
1523 | *************************************************/ | |
1524 | ||
1525 | /* | |
1526 | Arguments: | |
817d9f57 | 1527 | is_server channel specifier |
059ec3d9 PH |
1528 | buff buffer of data |
1529 | len number of bytes | |
1530 | ||
1531 | Returns: the number of bytes after a successful write, | |
1532 | -1 after a failed write | |
817d9f57 JH |
1533 | |
1534 | Used by both server-side and client-side TLS. | |
059ec3d9 PH |
1535 | */ |
1536 | ||
1537 | int | |
817d9f57 | 1538 | tls_write(BOOL is_server, const uschar *buff, size_t len) |
059ec3d9 PH |
1539 | { |
1540 | int outbytes; | |
1541 | int error; | |
1542 | int left = len; | |
817d9f57 | 1543 | SSL *ssl = is_server ? server_ssl : client_ssl; |
059ec3d9 | 1544 | |
c80c5570 | 1545 | DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left); |
059ec3d9 PH |
1546 | while (left > 0) |
1547 | { | |
c80c5570 | 1548 | DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left); |
059ec3d9 PH |
1549 | outbytes = SSL_write(ssl, CS buff, left); |
1550 | error = SSL_get_error(ssl, outbytes); | |
1551 | DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error); | |
1552 | switch (error) | |
1553 | { | |
1554 | case SSL_ERROR_SSL: | |
1555 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
1556 | log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring); | |
1557 | return -1; | |
1558 | ||
1559 | case SSL_ERROR_NONE: | |
1560 | left -= outbytes; | |
1561 | buff += outbytes; | |
1562 | break; | |
1563 | ||
1564 | case SSL_ERROR_ZERO_RETURN: | |
1565 | log_write(0, LOG_MAIN, "SSL channel closed on write"); | |
1566 | return -1; | |
1567 | ||
817d9f57 JH |
1568 | case SSL_ERROR_SYSCALL: |
1569 | log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s", | |
1570 | sender_fullhost ? sender_fullhost : US"<unknown>", | |
1571 | strerror(errno)); | |
1572 | ||
059ec3d9 PH |
1573 | default: |
1574 | log_write(0, LOG_MAIN, "SSL_write error %d", error); | |
1575 | return -1; | |
1576 | } | |
1577 | } | |
1578 | return len; | |
1579 | } | |
1580 | ||
1581 | ||
1582 | ||
1583 | /************************************************* | |
1584 | * Close down a TLS session * | |
1585 | *************************************************/ | |
1586 | ||
1587 | /* This is also called from within a delivery subprocess forked from the | |
1588 | daemon, to shut down the TLS library, without actually doing a shutdown (which | |
1589 | would tamper with the SSL session in the parent process). | |
1590 | ||
1591 | Arguments: TRUE if SSL_shutdown is to be called | |
1592 | Returns: nothing | |
817d9f57 JH |
1593 | |
1594 | Used by both server-side and client-side TLS. | |
059ec3d9 PH |
1595 | */ |
1596 | ||
1597 | void | |
817d9f57 | 1598 | tls_close(BOOL is_server, BOOL shutdown) |
059ec3d9 | 1599 | { |
817d9f57 | 1600 | SSL **sslp = is_server ? &server_ssl : &client_ssl; |
389ca47a | 1601 | int *fdp = is_server ? &tls_in.active : &tls_out.active; |
817d9f57 JH |
1602 | |
1603 | if (*fdp < 0) return; /* TLS was not active */ | |
059ec3d9 PH |
1604 | |
1605 | if (shutdown) | |
1606 | { | |
1607 | DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n"); | |
817d9f57 | 1608 | SSL_shutdown(*sslp); |
059ec3d9 PH |
1609 | } |
1610 | ||
817d9f57 JH |
1611 | SSL_free(*sslp); |
1612 | *sslp = NULL; | |
059ec3d9 | 1613 | |
817d9f57 | 1614 | *fdp = -1; |
059ec3d9 PH |
1615 | } |
1616 | ||
36f12725 NM |
1617 | |
1618 | ||
1619 | ||
3375e053 PP |
1620 | /************************************************* |
1621 | * Let tls_require_ciphers be checked at startup * | |
1622 | *************************************************/ | |
1623 | ||
1624 | /* The tls_require_ciphers option, if set, must be something which the | |
1625 | library can parse. | |
1626 | ||
1627 | Returns: NULL on success, or error message | |
1628 | */ | |
1629 | ||
1630 | uschar * | |
1631 | tls_validate_require_cipher(void) | |
1632 | { | |
1633 | SSL_CTX *ctx; | |
1634 | uschar *s, *expciphers, *err; | |
1635 | ||
1636 | /* this duplicates from tls_init(), we need a better "init just global | |
1637 | state, for no specific purpose" singleton function of our own */ | |
1638 | ||
1639 | SSL_load_error_strings(); | |
1640 | OpenSSL_add_ssl_algorithms(); | |
1641 | #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256) | |
1642 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the | |
1643 | list of available digests. */ | |
1644 | EVP_add_digest(EVP_sha256()); | |
1645 | #endif | |
1646 | ||
1647 | if (!(tls_require_ciphers && *tls_require_ciphers)) | |
1648 | return NULL; | |
1649 | ||
1650 | if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers)) | |
1651 | return US"failed to expand tls_require_ciphers"; | |
1652 | ||
1653 | if (!(expciphers && *expciphers)) | |
1654 | return NULL; | |
1655 | ||
1656 | /* normalisation ripped from above */ | |
1657 | s = expciphers; | |
1658 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } | |
1659 | ||
1660 | err = NULL; | |
1661 | ||
1662 | ctx = SSL_CTX_new(SSLv23_server_method()); | |
1663 | if (!ctx) | |
1664 | { | |
1665 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
1666 | return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring); | |
1667 | } | |
1668 | ||
1669 | DEBUG(D_tls) | |
1670 | debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers); | |
1671 | ||
1672 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) | |
1673 | { | |
1674 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
1675 | err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers); | |
1676 | } | |
1677 | ||
1678 | SSL_CTX_free(ctx); | |
1679 | ||
1680 | return err; | |
1681 | } | |
1682 | ||
1683 | ||
1684 | ||
1685 | ||
36f12725 NM |
1686 | /************************************************* |
1687 | * Report the library versions. * | |
1688 | *************************************************/ | |
1689 | ||
1690 | /* There have historically been some issues with binary compatibility in | |
1691 | OpenSSL libraries; if Exim (like many other applications) is built against | |
1692 | one version of OpenSSL but the run-time linker picks up another version, | |
1693 | it can result in serious failures, including crashing with a SIGSEGV. So | |
1694 | report the version found by the compiler and the run-time version. | |
1695 | ||
1696 | Arguments: a FILE* to print the results to | |
1697 | Returns: nothing | |
1698 | */ | |
1699 | ||
1700 | void | |
1701 | tls_version_report(FILE *f) | |
1702 | { | |
754a0503 PP |
1703 | fprintf(f, "Library version: OpenSSL: Compile: %s\n" |
1704 | " Runtime: %s\n", | |
1705 | OPENSSL_VERSION_TEXT, | |
1706 | SSLeay_version(SSLEAY_VERSION)); | |
36f12725 NM |
1707 | } |
1708 | ||
9e3331ea TK |
1709 | |
1710 | ||
1711 | ||
1712 | /************************************************* | |
17c76198 | 1713 | * Random number generation * |
9e3331ea TK |
1714 | *************************************************/ |
1715 | ||
1716 | /* Pseudo-random number generation. The result is not expected to be | |
1717 | cryptographically strong but not so weak that someone will shoot themselves | |
1718 | in the foot using it as a nonce in input in some email header scheme or | |
1719 | whatever weirdness they'll twist this into. The result should handle fork() | |
1720 | and avoid repeating sequences. OpenSSL handles that for us. | |
1721 | ||
1722 | Arguments: | |
1723 | max range maximum | |
1724 | Returns a random number in range [0, max-1] | |
1725 | */ | |
1726 | ||
1727 | int | |
17c76198 | 1728 | vaguely_random_number(int max) |
9e3331ea TK |
1729 | { |
1730 | unsigned int r; | |
1731 | int i, needed_len; | |
1732 | uschar *p; | |
1733 | uschar smallbuf[sizeof(r)]; | |
1734 | ||
1735 | if (max <= 1) | |
1736 | return 0; | |
1737 | ||
1738 | /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */ | |
1739 | if (!RAND_status()) | |
1740 | { | |
1741 | randstuff r; | |
1742 | gettimeofday(&r.tv, NULL); | |
1743 | r.p = getpid(); | |
1744 | ||
1745 | RAND_seed((uschar *)(&r), sizeof(r)); | |
1746 | } | |
1747 | /* We're after pseudo-random, not random; if we still don't have enough data | |
1748 | in the internal PRNG then our options are limited. We could sleep and hope | |
1749 | for entropy to come along (prayer technique) but if the system is so depleted | |
1750 | in the first place then something is likely to just keep taking it. Instead, | |
1751 | we'll just take whatever little bit of pseudo-random we can still manage to | |
1752 | get. */ | |
1753 | ||
1754 | needed_len = sizeof(r); | |
1755 | /* Don't take 8 times more entropy than needed if int is 8 octets and we were | |
1756 | asked for a number less than 10. */ | |
1757 | for (r = max, i = 0; r; ++i) | |
1758 | r >>= 1; | |
1759 | i = (i + 7) / 8; | |
1760 | if (i < needed_len) | |
1761 | needed_len = i; | |
1762 | ||
1763 | /* We do not care if crypto-strong */ | |
17c76198 PP |
1764 | i = RAND_pseudo_bytes(smallbuf, needed_len); |
1765 | if (i < 0) | |
1766 | { | |
1767 | DEBUG(D_all) | |
1768 | debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n"); | |
1769 | return vaguely_random_number_fallback(max); | |
1770 | } | |
1771 | ||
9e3331ea TK |
1772 | r = 0; |
1773 | for (p = smallbuf; needed_len; --needed_len, ++p) | |
1774 | { | |
1775 | r *= 256; | |
1776 | r += *p; | |
1777 | } | |
1778 | ||
1779 | /* We don't particularly care about weighted results; if someone wants | |
1780 | smooth distribution and cares enough then they should submit a patch then. */ | |
1781 | return r % max; | |
1782 | } | |
1783 | ||
77bb000f PP |
1784 | |
1785 | ||
1786 | ||
1787 | /************************************************* | |
1788 | * OpenSSL option parse * | |
1789 | *************************************************/ | |
1790 | ||
1791 | /* Parse one option for tls_openssl_options_parse below | |
1792 | ||
1793 | Arguments: | |
1794 | name one option name | |
1795 | value place to store a value for it | |
1796 | Returns success or failure in parsing | |
1797 | */ | |
1798 | ||
1799 | struct exim_openssl_option { | |
1800 | uschar *name; | |
1801 | long value; | |
1802 | }; | |
1803 | /* We could use a macro to expand, but we need the ifdef and not all the | |
1804 | options document which version they were introduced in. Policylet: include | |
1805 | all options unless explicitly for DTLS, let the administrator choose which | |
1806 | to apply. | |
1807 | ||
1808 | This list is current as of: | |
c80c5570 | 1809 | ==> 1.0.1b <== */ |
77bb000f PP |
1810 | static struct exim_openssl_option exim_openssl_options[] = { |
1811 | /* KEEP SORTED ALPHABETICALLY! */ | |
1812 | #ifdef SSL_OP_ALL | |
73a46702 | 1813 | { US"all", SSL_OP_ALL }, |
77bb000f PP |
1814 | #endif |
1815 | #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION | |
73a46702 | 1816 | { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION }, |
77bb000f PP |
1817 | #endif |
1818 | #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE | |
73a46702 | 1819 | { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE }, |
77bb000f PP |
1820 | #endif |
1821 | #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS | |
73a46702 | 1822 | { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS }, |
77bb000f PP |
1823 | #endif |
1824 | #ifdef SSL_OP_EPHEMERAL_RSA | |
73a46702 | 1825 | { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA }, |
77bb000f PP |
1826 | #endif |
1827 | #ifdef SSL_OP_LEGACY_SERVER_CONNECT | |
73a46702 | 1828 | { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT }, |
77bb000f PP |
1829 | #endif |
1830 | #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER | |
73a46702 | 1831 | { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER }, |
77bb000f PP |
1832 | #endif |
1833 | #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG | |
73a46702 | 1834 | { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG }, |
77bb000f PP |
1835 | #endif |
1836 | #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING | |
73a46702 | 1837 | { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING }, |
77bb000f PP |
1838 | #endif |
1839 | #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG | |
73a46702 | 1840 | { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG }, |
77bb000f PP |
1841 | #endif |
1842 | #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG | |
73a46702 | 1843 | { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG }, |
77bb000f | 1844 | #endif |
c80c5570 PP |
1845 | #ifdef SSL_OP_NO_COMPRESSION |
1846 | { US"no_compression", SSL_OP_NO_COMPRESSION }, | |
1847 | #endif | |
77bb000f | 1848 | #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION |
73a46702 | 1849 | { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION }, |
77bb000f | 1850 | #endif |
c0c7b2da PP |
1851 | #ifdef SSL_OP_NO_SSLv2 |
1852 | { US"no_sslv2", SSL_OP_NO_SSLv2 }, | |
1853 | #endif | |
1854 | #ifdef SSL_OP_NO_SSLv3 | |
1855 | { US"no_sslv3", SSL_OP_NO_SSLv3 }, | |
1856 | #endif | |
1857 | #ifdef SSL_OP_NO_TICKET | |
1858 | { US"no_ticket", SSL_OP_NO_TICKET }, | |
1859 | #endif | |
1860 | #ifdef SSL_OP_NO_TLSv1 | |
1861 | { US"no_tlsv1", SSL_OP_NO_TLSv1 }, | |
1862 | #endif | |
c80c5570 PP |
1863 | #ifdef SSL_OP_NO_TLSv1_1 |
1864 | #if SSL_OP_NO_TLSv1_1 == 0x00000400L | |
1865 | /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */ | |
1866 | #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring | |
1867 | #else | |
1868 | { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 }, | |
1869 | #endif | |
1870 | #endif | |
1871 | #ifdef SSL_OP_NO_TLSv1_2 | |
1872 | { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 }, | |
1873 | #endif | |
77bb000f | 1874 | #ifdef SSL_OP_SINGLE_DH_USE |
73a46702 | 1875 | { US"single_dh_use", SSL_OP_SINGLE_DH_USE }, |
77bb000f PP |
1876 | #endif |
1877 | #ifdef SSL_OP_SINGLE_ECDH_USE | |
73a46702 | 1878 | { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE }, |
77bb000f PP |
1879 | #endif |
1880 | #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG | |
73a46702 | 1881 | { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG }, |
77bb000f PP |
1882 | #endif |
1883 | #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG | |
73a46702 | 1884 | { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG }, |
77bb000f PP |
1885 | #endif |
1886 | #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG | |
73a46702 | 1887 | { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG }, |
77bb000f PP |
1888 | #endif |
1889 | #ifdef SSL_OP_TLS_D5_BUG | |
73a46702 | 1890 | { US"tls_d5_bug", SSL_OP_TLS_D5_BUG }, |
77bb000f PP |
1891 | #endif |
1892 | #ifdef SSL_OP_TLS_ROLLBACK_BUG | |
73a46702 | 1893 | { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG }, |
77bb000f PP |
1894 | #endif |
1895 | }; | |
1896 | static int exim_openssl_options_size = | |
1897 | sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option); | |
1898 | ||
c80c5570 | 1899 | |
77bb000f PP |
1900 | static BOOL |
1901 | tls_openssl_one_option_parse(uschar *name, long *value) | |
1902 | { | |
1903 | int first = 0; | |
1904 | int last = exim_openssl_options_size; | |
1905 | while (last > first) | |
1906 | { | |
1907 | int middle = (first + last)/2; | |
1908 | int c = Ustrcmp(name, exim_openssl_options[middle].name); | |
1909 | if (c == 0) | |
1910 | { | |
1911 | *value = exim_openssl_options[middle].value; | |
1912 | return TRUE; | |
1913 | } | |
1914 | else if (c > 0) | |
1915 | first = middle + 1; | |
1916 | else | |
1917 | last = middle; | |
1918 | } | |
1919 | return FALSE; | |
1920 | } | |
1921 | ||
1922 | ||
1923 | ||
1924 | ||
1925 | /************************************************* | |
1926 | * OpenSSL option parsing logic * | |
1927 | *************************************************/ | |
1928 | ||
1929 | /* OpenSSL has a number of compatibility options which an administrator might | |
1930 | reasonably wish to set. Interpret a list similarly to decode_bits(), so that | |
1931 | we look like log_selector. | |
1932 | ||
1933 | Arguments: | |
1934 | option_spec the administrator-supplied string of options | |
1935 | results ptr to long storage for the options bitmap | |
1936 | Returns success or failure | |
1937 | */ | |
1938 | ||
1939 | BOOL | |
1940 | tls_openssl_options_parse(uschar *option_spec, long *results) | |
1941 | { | |
1942 | long result, item; | |
1943 | uschar *s, *end; | |
1944 | uschar keep_c; | |
1945 | BOOL adding, item_parsed; | |
1946 | ||
0e944a0d | 1947 | result = 0L; |
b1770b6e | 1948 | /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed |
da3ad30d | 1949 | * from default because it increases BEAST susceptibility. */ |
f0f5a555 PP |
1950 | #ifdef SSL_OP_NO_SSLv2 |
1951 | result |= SSL_OP_NO_SSLv2; | |
1952 | #endif | |
77bb000f PP |
1953 | |
1954 | if (option_spec == NULL) | |
1955 | { | |
1956 | *results = result; | |
1957 | return TRUE; | |
1958 | } | |
1959 | ||
1960 | for (s=option_spec; *s != '\0'; /**/) | |
1961 | { | |
1962 | while (isspace(*s)) ++s; | |
1963 | if (*s == '\0') | |
1964 | break; | |
1965 | if (*s != '+' && *s != '-') | |
1966 | { | |
1967 | DEBUG(D_tls) debug_printf("malformed openssl option setting: " | |
0e944a0d | 1968 | "+ or - expected but found \"%s\"\n", s); |
77bb000f PP |
1969 | return FALSE; |
1970 | } | |
1971 | adding = *s++ == '+'; | |
1972 | for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ; | |
1973 | keep_c = *end; | |
1974 | *end = '\0'; | |
1975 | item_parsed = tls_openssl_one_option_parse(s, &item); | |
1976 | if (!item_parsed) | |
1977 | { | |
0e944a0d | 1978 | DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s); |
77bb000f PP |
1979 | return FALSE; |
1980 | } | |
1981 | DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n", | |
1982 | adding ? "adding" : "removing", result, item, s); | |
1983 | if (adding) | |
1984 | result |= item; | |
1985 | else | |
1986 | result &= ~item; | |
1987 | *end = keep_c; | |
1988 | s = end; | |
1989 | } | |
1990 | ||
1991 | *results = result; | |
1992 | return TRUE; | |
1993 | } | |
1994 | ||
059ec3d9 | 1995 | /* End of tls-openssl.c */ |