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420a0d19 CE |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | ||
2ea97746 | 5 | /* Copyright (c) University of Cambridge 1995 - 2018 */ |
420a0d19 CE |
6 | /* See the file NOTICE for conditions of use and distribution. */ |
7 | ||
8 | /* Copyright (c) Phil Pennock 2012 */ | |
9 | ||
10 | /* This file provides TLS/SSL support for Exim using the GnuTLS library, | |
11 | one of the available supported implementations. This file is #included into | |
12 | tls.c when USE_GNUTLS has been set. | |
13 | ||
14 | The code herein is a revamp of GnuTLS integration using the current APIs; the | |
15 | original tls-gnu.c was based on a patch which was contributed by Nikos | |
2ea97746 | 16 | Mavrogiannopoulos. The revamp is partially a rewrite, partially cut&paste as |
420a0d19 CE |
17 | appropriate. |
18 | ||
19 | APIs current as of GnuTLS 2.12.18; note that the GnuTLS manual is for GnuTLS 3, | |
20 | which is not widely deployed by OS vendors. Will note issues below, which may | |
21 | assist in updating the code in the future. Another sources of hints is | |
22 | mod_gnutls for Apache (SNI callback registration and handling). | |
23 | ||
24 | Keeping client and server variables more split than before and is currently | |
25 | the norm, in anticipation of TLS in ACL callouts. | |
26 | ||
27 | I wanted to switch to gnutls_certificate_set_verify_function() so that | |
28 | certificate rejection could happen during handshake where it belongs, rather | |
29 | than being dropped afterwards, but that was introduced in 2.10.0 and Debian | |
30 | (6.0.5) is still on 2.8.6. So for now we have to stick with sub-par behaviour. | |
31 | ||
32 | (I wasn't looking for libraries quite that old, when updating to get rid of | |
33 | compiler warnings of deprecated APIs. If it turns out that a lot of the rest | |
34 | require current GnuTLS, then we'll drop support for the ancient libraries). | |
35 | */ | |
36 | ||
37 | #include <gnutls/gnutls.h> | |
38 | /* needed for cert checks in verification and DN extraction: */ | |
39 | #include <gnutls/x509.h> | |
40 | /* man-page is incorrect, gnutls_rnd() is not in gnutls.h: */ | |
41 | #include <gnutls/crypto.h> | |
2ea97746 | 42 | |
420a0d19 CE |
43 | /* needed to disable PKCS11 autoload unless requested */ |
44 | #if GNUTLS_VERSION_NUMBER >= 0x020c00 | |
45 | # include <gnutls/pkcs11.h> | |
2ea97746 | 46 | # define SUPPORT_PARAM_TO_PK_BITS |
420a0d19 CE |
47 | #endif |
48 | #if GNUTLS_VERSION_NUMBER < 0x030103 && !defined(DISABLE_OCSP) | |
49 | # warning "GnuTLS library version too old; define DISABLE_OCSP in Makefile" | |
50 | # define DISABLE_OCSP | |
51 | #endif | |
2ea97746 CE |
52 | #if GNUTLS_VERSION_NUMBER < 0x020a00 && !defined(DISABLE_EVENT) |
53 | # warning "GnuTLS library version too old; tls:cert event unsupported" | |
54 | # define DISABLE_EVENT | |
55 | #endif | |
56 | #if GNUTLS_VERSION_NUMBER >= 0x030306 | |
57 | # define SUPPORT_CA_DIR | |
58 | #else | |
59 | # undef SUPPORT_CA_DIR | |
60 | #endif | |
61 | #if GNUTLS_VERSION_NUMBER >= 0x030014 | |
62 | # define SUPPORT_SYSDEFAULT_CABUNDLE | |
63 | #endif | |
64 | #if GNUTLS_VERSION_NUMBER >= 0x030104 | |
65 | # define GNUTLS_CERT_VFY_STATUS_PRINT | |
66 | #endif | |
67 | #if GNUTLS_VERSION_NUMBER >= 0x030109 | |
68 | # define SUPPORT_CORK | |
69 | #endif | |
70 | #if GNUTLS_VERSION_NUMBER >= 0x030506 && !defined(DISABLE_OCSP) | |
71 | # define SUPPORT_SRV_OCSP_STACK | |
72 | #endif | |
73 | ||
74 | #ifdef SUPPORT_DANE | |
75 | # if GNUTLS_VERSION_NUMBER >= 0x030000 | |
76 | # define DANESSL_USAGE_DANE_TA 2 | |
77 | # define DANESSL_USAGE_DANE_EE 3 | |
78 | # else | |
79 | # error GnuTLS version too early for DANE | |
80 | # endif | |
81 | # if GNUTLS_VERSION_NUMBER < 0x999999 | |
82 | # define GNUTLS_BROKEN_DANE_VALIDATION | |
83 | # endif | |
84 | #endif | |
420a0d19 CE |
85 | |
86 | #ifndef DISABLE_OCSP | |
87 | # include <gnutls/ocsp.h> | |
88 | #endif | |
2ea97746 CE |
89 | #ifdef SUPPORT_DANE |
90 | # include <gnutls/dane.h> | |
91 | #endif | |
420a0d19 CE |
92 | |
93 | /* GnuTLS 2 vs 3 | |
94 | ||
95 | GnuTLS 3 only: | |
96 | gnutls_global_set_audit_log_function() | |
97 | ||
98 | Changes: | |
99 | gnutls_certificate_verify_peers2(): is new, drop the 2 for old version | |
100 | */ | |
101 | ||
102 | /* Local static variables for GnuTLS */ | |
103 | ||
104 | /* Values for verify_requirement */ | |
105 | ||
106 | enum peer_verify_requirement | |
2ea97746 | 107 | { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED, VERIFY_DANE }; |
420a0d19 CE |
108 | |
109 | /* This holds most state for server or client; with this, we can set up an | |
110 | outbound TLS-enabled connection in an ACL callout, while not stomping all | |
111 | over the TLS variables available for expansion. | |
112 | ||
113 | Some of these correspond to variables in globals.c; those variables will | |
114 | be set to point to content in one of these instances, as appropriate for | |
115 | the stage of the process lifetime. | |
116 | ||
117 | Not handled here: global tls_channelbinding_b64. | |
118 | */ | |
119 | ||
120 | typedef struct exim_gnutls_state { | |
121 | gnutls_session_t session; | |
122 | gnutls_certificate_credentials_t x509_cred; | |
123 | gnutls_priority_t priority_cache; | |
124 | enum peer_verify_requirement verify_requirement; | |
125 | int fd_in; | |
126 | int fd_out; | |
127 | BOOL peer_cert_verified; | |
2ea97746 | 128 | BOOL peer_dane_verified; |
420a0d19 CE |
129 | BOOL trigger_sni_changes; |
130 | BOOL have_set_peerdn; | |
2ea97746 CE |
131 | const struct host_item *host; /* NULL if server */ |
132 | gnutls_x509_crt_t peercert; | |
420a0d19 CE |
133 | uschar *peerdn; |
134 | uschar *ciphersuite; | |
135 | uschar *received_sni; | |
136 | ||
137 | const uschar *tls_certificate; | |
138 | const uschar *tls_privatekey; | |
139 | const uschar *tls_sni; /* client send only, not received */ | |
140 | const uschar *tls_verify_certificates; | |
141 | const uschar *tls_crl; | |
142 | const uschar *tls_require_ciphers; | |
143 | ||
144 | uschar *exp_tls_certificate; | |
145 | uschar *exp_tls_privatekey; | |
146 | uschar *exp_tls_verify_certificates; | |
147 | uschar *exp_tls_crl; | |
148 | uschar *exp_tls_require_ciphers; | |
2ea97746 CE |
149 | const uschar *exp_tls_verify_cert_hostnames; |
150 | #ifndef DISABLE_EVENT | |
151 | uschar *event_action; | |
152 | #endif | |
153 | #ifdef SUPPORT_DANE | |
154 | char * const * dane_data; | |
155 | const int * dane_data_len; | |
420a0d19 CE |
156 | #endif |
157 | ||
158 | tls_support *tlsp; /* set in tls_init() */ | |
159 | ||
160 | uschar *xfer_buffer; | |
161 | int xfer_buffer_lwm; | |
162 | int xfer_buffer_hwm; | |
2ea97746 CE |
163 | BOOL xfer_eof; /*XXX never gets set! */ |
164 | BOOL xfer_error; | |
420a0d19 CE |
165 | } exim_gnutls_state_st; |
166 | ||
167 | static const exim_gnutls_state_st exim_gnutls_state_init = { | |
2ea97746 CE |
168 | .session = NULL, |
169 | .x509_cred = NULL, | |
170 | .priority_cache = NULL, | |
171 | .verify_requirement = VERIFY_NONE, | |
172 | .fd_in = -1, | |
173 | .fd_out = -1, | |
174 | .peer_cert_verified = FALSE, | |
175 | .peer_dane_verified = FALSE, | |
176 | .trigger_sni_changes =FALSE, | |
177 | .have_set_peerdn = FALSE, | |
178 | .host = NULL, | |
179 | .peercert = NULL, | |
180 | .peerdn = NULL, | |
181 | .ciphersuite = NULL, | |
182 | .received_sni = NULL, | |
183 | ||
184 | .tls_certificate = NULL, | |
185 | .tls_privatekey = NULL, | |
186 | .tls_sni = NULL, | |
187 | .tls_verify_certificates = NULL, | |
188 | .tls_crl = NULL, | |
189 | .tls_require_ciphers =NULL, | |
190 | ||
191 | .exp_tls_certificate = NULL, | |
192 | .exp_tls_privatekey = NULL, | |
193 | .exp_tls_verify_certificates = NULL, | |
194 | .exp_tls_crl = NULL, | |
195 | .exp_tls_require_ciphers = NULL, | |
196 | .exp_tls_verify_cert_hostnames = NULL, | |
197 | #ifndef DISABLE_EVENT | |
198 | .event_action = NULL, | |
420a0d19 | 199 | #endif |
2ea97746 CE |
200 | .tlsp = NULL, |
201 | ||
202 | .xfer_buffer = NULL, | |
203 | .xfer_buffer_lwm = 0, | |
204 | .xfer_buffer_hwm = 0, | |
205 | .xfer_eof = FALSE, | |
206 | .xfer_error = FALSE, | |
420a0d19 CE |
207 | }; |
208 | ||
209 | /* Not only do we have our own APIs which don't pass around state, assuming | |
210 | it's held in globals, GnuTLS doesn't appear to let us register callback data | |
211 | for callbacks, or as part of the session, so we have to keep a "this is the | |
212 | context we're currently dealing with" pointer and rely upon being | |
213 | single-threaded to keep from processing data on an inbound TLS connection while | |
214 | talking to another TLS connection for an outbound check. This does mean that | |
215 | there's no way for heart-beats to be responded to, for the duration of the | |
2ea97746 CE |
216 | second connection. |
217 | XXX But see gnutls_session_get_ptr() | |
218 | */ | |
420a0d19 | 219 | |
2ea97746 | 220 | static exim_gnutls_state_st state_server; |
420a0d19 CE |
221 | |
222 | /* dh_params are initialised once within the lifetime of a process using TLS; | |
223 | if we used TLS in a long-lived daemon, we'd have to reconsider this. But we | |
224 | don't want to repeat this. */ | |
225 | ||
226 | static gnutls_dh_params_t dh_server_params = NULL; | |
227 | ||
228 | /* No idea how this value was chosen; preserving it. Default is 3600. */ | |
229 | ||
230 | static const int ssl_session_timeout = 200; | |
231 | ||
232 | static const char * const exim_default_gnutls_priority = "NORMAL"; | |
233 | ||
234 | /* Guard library core initialisation */ | |
235 | ||
236 | static BOOL exim_gnutls_base_init_done = FALSE; | |
237 | ||
2ea97746 CE |
238 | #ifndef DISABLE_OCSP |
239 | static BOOL gnutls_buggy_ocsp = FALSE; | |
240 | #endif | |
241 | ||
420a0d19 CE |
242 | |
243 | /* ------------------------------------------------------------------------ */ | |
244 | /* macros */ | |
245 | ||
246 | #define MAX_HOST_LEN 255 | |
247 | ||
248 | /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup | |
249 | the library logging; a value less than 0 disables the calls to set up logging | |
2ea97746 CE |
250 | callbacks. Possibly GNuTLS also looks for an environment variable |
251 | "GNUTLS_DEBUG_LEVEL". */ | |
420a0d19 | 252 | #ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL |
2ea97746 | 253 | # define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1 |
420a0d19 CE |
254 | #endif |
255 | ||
256 | #ifndef EXIM_CLIENT_DH_MIN_BITS | |
2ea97746 | 257 | # define EXIM_CLIENT_DH_MIN_BITS 1024 |
420a0d19 CE |
258 | #endif |
259 | ||
260 | /* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we | |
261 | can ask for a bit-strength. Without that, we stick to the constant we had | |
262 | before, for now. */ | |
263 | #ifndef EXIM_SERVER_DH_BITS_PRE2_12 | |
2ea97746 | 264 | # define EXIM_SERVER_DH_BITS_PRE2_12 1024 |
420a0d19 CE |
265 | #endif |
266 | ||
2ea97746 CE |
267 | #define exim_gnutls_err_check(rc, Label) do { \ |
268 | if ((rc) != GNUTLS_E_SUCCESS) \ | |
269 | return tls_error((Label), US gnutls_strerror(rc), host, errstr); \ | |
270 | } while (0) | |
420a0d19 | 271 | |
2ea97746 CE |
272 | #define expand_check_tlsvar(Varname, errstr) \ |
273 | expand_check(state->Varname, US #Varname, &state->exp_##Varname, errstr) | |
420a0d19 CE |
274 | |
275 | #if GNUTLS_VERSION_NUMBER >= 0x020c00 | |
276 | # define HAVE_GNUTLS_SESSION_CHANNEL_BINDING | |
277 | # define HAVE_GNUTLS_SEC_PARAM_CONSTANTS | |
278 | # define HAVE_GNUTLS_RND | |
279 | /* The security fix we provide with the gnutls_allow_auto_pkcs11 option | |
280 | * (4.82 PP/09) introduces a compatibility regression. The symbol simply | |
281 | * isn't available sometimes, so this needs to become a conditional | |
282 | * compilation; the sanest way to deal with this being a problem on | |
283 | * older OSes is to block it in the Local/Makefile with this compiler | |
284 | * definition */ | |
285 | # ifndef AVOID_GNUTLS_PKCS11 | |
286 | # define HAVE_GNUTLS_PKCS11 | |
287 | # endif /* AVOID_GNUTLS_PKCS11 */ | |
288 | #endif | |
289 | ||
290 | ||
291 | ||
292 | ||
293 | /* ------------------------------------------------------------------------ */ | |
294 | /* Callback declarations */ | |
295 | ||
296 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 | |
297 | static void exim_gnutls_logger_cb(int level, const char *message); | |
298 | #endif | |
299 | ||
300 | static int exim_sni_handling_cb(gnutls_session_t session); | |
301 | ||
302 | #ifndef DISABLE_OCSP | |
303 | static int server_ocsp_stapling_cb(gnutls_session_t session, void * ptr, | |
304 | gnutls_datum_t * ocsp_response); | |
305 | #endif | |
306 | ||
307 | ||
308 | ||
309 | /* ------------------------------------------------------------------------ */ | |
310 | /* Static functions */ | |
311 | ||
312 | /************************************************* | |
313 | * Handle TLS error * | |
314 | *************************************************/ | |
315 | ||
316 | /* Called from lots of places when errors occur before actually starting to do | |
317 | the TLS handshake, that is, while the session is still in clear. Always returns | |
318 | DEFER for a server and FAIL for a client so that most calls can use "return | |
319 | tls_error(...)" to do this processing and then give an appropriate return. A | |
320 | single function is used for both server and client, because it is called from | |
321 | some shared functions. | |
322 | ||
323 | Argument: | |
324 | prefix text to include in the logged error | |
325 | msg additional error string (may be NULL) | |
326 | usually obtained from gnutls_strerror() | |
327 | host NULL if setting up a server; | |
328 | the connected host if setting up a client | |
2ea97746 | 329 | errstr pointer to returned error string |
420a0d19 CE |
330 | |
331 | Returns: OK/DEFER/FAIL | |
332 | */ | |
333 | ||
334 | static int | |
2ea97746 CE |
335 | tls_error(const uschar *prefix, const uschar *msg, const host_item *host, |
336 | uschar ** errstr) | |
420a0d19 | 337 | { |
2ea97746 CE |
338 | if (errstr) |
339 | *errstr = string_sprintf("(%s)%s%s", prefix, msg ? ": " : "", msg ? msg : US""); | |
340 | return host ? FAIL : DEFER; | |
420a0d19 CE |
341 | } |
342 | ||
343 | ||
344 | ||
345 | ||
346 | /************************************************* | |
347 | * Deal with logging errors during I/O * | |
348 | *************************************************/ | |
349 | ||
350 | /* We have to get the identity of the peer from saved data. | |
351 | ||
352 | Argument: | |
353 | state the current GnuTLS exim state container | |
354 | rc the GnuTLS error code, or 0 if it's a local error | |
355 | when text identifying read or write | |
356 | text local error text when ec is 0 | |
357 | ||
358 | Returns: nothing | |
359 | */ | |
360 | ||
361 | static void | |
362 | record_io_error(exim_gnutls_state_st *state, int rc, uschar *when, uschar *text) | |
363 | { | |
2ea97746 CE |
364 | const uschar * msg; |
365 | uschar * errstr; | |
420a0d19 CE |
366 | |
367 | if (rc == GNUTLS_E_FATAL_ALERT_RECEIVED) | |
2ea97746 | 368 | msg = string_sprintf("%s: %s", US gnutls_strerror(rc), |
420a0d19 CE |
369 | US gnutls_alert_get_name(gnutls_alert_get(state->session))); |
370 | else | |
2ea97746 | 371 | msg = US gnutls_strerror(rc); |
420a0d19 | 372 | |
2ea97746 CE |
373 | (void) tls_error(when, msg, state->host, &errstr); |
374 | ||
375 | if (state->host) | |
376 | log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection %s", | |
377 | state->host->name, state->host->address, errstr); | |
378 | else | |
379 | { | |
380 | uschar * conn_info = smtp_get_connection_info(); | |
381 | if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5; | |
382 | /* I'd like to get separated H= here, but too hard for now */ | |
383 | log_write(0, LOG_MAIN, "TLS error on %s %s", conn_info, errstr); | |
384 | } | |
420a0d19 CE |
385 | } |
386 | ||
387 | ||
388 | ||
389 | ||
390 | /************************************************* | |
391 | * Set various Exim expansion vars * | |
392 | *************************************************/ | |
393 | ||
394 | #define exim_gnutls_cert_err(Label) \ | |
395 | do \ | |
396 | { \ | |
397 | if (rc != GNUTLS_E_SUCCESS) \ | |
398 | { \ | |
399 | DEBUG(D_tls) debug_printf("TLS: cert problem: %s: %s\n", \ | |
400 | (Label), gnutls_strerror(rc)); \ | |
401 | return rc; \ | |
402 | } \ | |
403 | } while (0) | |
404 | ||
405 | static int | |
2ea97746 | 406 | import_cert(const gnutls_datum_t * cert, gnutls_x509_crt_t * crtp) |
420a0d19 CE |
407 | { |
408 | int rc; | |
409 | ||
410 | rc = gnutls_x509_crt_init(crtp); | |
411 | exim_gnutls_cert_err(US"gnutls_x509_crt_init (crt)"); | |
412 | ||
413 | rc = gnutls_x509_crt_import(*crtp, cert, GNUTLS_X509_FMT_DER); | |
414 | exim_gnutls_cert_err(US"failed to import certificate [gnutls_x509_crt_import(cert)]"); | |
415 | ||
416 | return rc; | |
417 | } | |
418 | ||
419 | #undef exim_gnutls_cert_err | |
420 | ||
421 | ||
422 | /* We set various Exim global variables from the state, once a session has | |
423 | been established. With TLS callouts, may need to change this to stack | |
424 | variables, or just re-call it with the server state after client callout | |
425 | has finished. | |
426 | ||
427 | Make sure anything set here is unset in tls_getc(). | |
428 | ||
429 | Sets: | |
430 | tls_active fd | |
431 | tls_bits strength indicator | |
432 | tls_certificate_verified bool indicator | |
433 | tls_channelbinding_b64 for some SASL mechanisms | |
434 | tls_cipher a string | |
435 | tls_peercert pointer to library internal | |
436 | tls_peerdn a string | |
437 | tls_sni a (UTF-8) string | |
438 | tls_ourcert pointer to library internal | |
439 | ||
440 | Argument: | |
441 | state the relevant exim_gnutls_state_st * | |
442 | */ | |
443 | ||
444 | static void | |
445 | extract_exim_vars_from_tls_state(exim_gnutls_state_st * state) | |
446 | { | |
447 | gnutls_cipher_algorithm_t cipher; | |
448 | #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING | |
449 | int old_pool; | |
450 | int rc; | |
451 | gnutls_datum_t channel; | |
452 | #endif | |
453 | tls_support * tlsp = state->tlsp; | |
454 | ||
2ea97746 CE |
455 | tlsp->active.sock = state->fd_out; |
456 | tlsp->active.tls_ctx = state; | |
420a0d19 CE |
457 | |
458 | cipher = gnutls_cipher_get(state->session); | |
459 | /* returns size in "bytes" */ | |
460 | tlsp->bits = gnutls_cipher_get_key_size(cipher) * 8; | |
461 | ||
462 | tlsp->cipher = state->ciphersuite; | |
463 | ||
464 | DEBUG(D_tls) debug_printf("cipher: %s\n", state->ciphersuite); | |
465 | ||
466 | tlsp->certificate_verified = state->peer_cert_verified; | |
2ea97746 CE |
467 | #ifdef SUPPORT_DANE |
468 | tlsp->dane_verified = state->peer_dane_verified; | |
469 | #endif | |
420a0d19 CE |
470 | |
471 | /* note that tls_channelbinding_b64 is not saved to the spool file, since it's | |
472 | only available for use for authenticators while this TLS session is running. */ | |
473 | ||
474 | tls_channelbinding_b64 = NULL; | |
475 | #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING | |
476 | channel.data = NULL; | |
477 | channel.size = 0; | |
478 | rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel); | |
479 | if (rc) { | |
480 | DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc)); | |
481 | } else { | |
482 | old_pool = store_pool; | |
483 | store_pool = POOL_PERM; | |
2ea97746 | 484 | tls_channelbinding_b64 = b64encode(channel.data, (int)channel.size); |
420a0d19 CE |
485 | store_pool = old_pool; |
486 | DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage.\n"); | |
487 | } | |
488 | #endif | |
489 | ||
490 | /* peercert is set in peer_status() */ | |
491 | tlsp->peerdn = state->peerdn; | |
492 | tlsp->sni = state->received_sni; | |
493 | ||
494 | /* record our certificate */ | |
495 | { | |
2ea97746 | 496 | const gnutls_datum_t * cert = gnutls_certificate_get_ours(state->session); |
420a0d19 CE |
497 | gnutls_x509_crt_t crt; |
498 | ||
499 | tlsp->ourcert = cert && import_cert(cert, &crt)==0 ? crt : NULL; | |
500 | } | |
501 | } | |
502 | ||
503 | ||
504 | ||
505 | ||
506 | /************************************************* | |
507 | * Setup up DH parameters * | |
508 | *************************************************/ | |
509 | ||
510 | /* Generating the D-H parameters may take a long time. They only need to | |
511 | be re-generated every so often, depending on security policy. What we do is to | |
512 | keep these parameters in a file in the spool directory. If the file does not | |
513 | exist, we generate them. This means that it is easy to cause a regeneration. | |
514 | ||
515 | The new file is written as a temporary file and renamed, so that an incomplete | |
516 | file is never present. If two processes both compute some new parameters, you | |
517 | waste a bit of effort, but it doesn't seem worth messing around with locking to | |
518 | prevent this. | |
519 | ||
520 | Returns: OK/DEFER/FAIL | |
521 | */ | |
522 | ||
523 | static int | |
2ea97746 | 524 | init_server_dh(uschar ** errstr) |
420a0d19 CE |
525 | { |
526 | int fd, rc; | |
527 | unsigned int dh_bits; | |
2ea97746 | 528 | gnutls_datum_t m; |
420a0d19 CE |
529 | uschar filename_buf[PATH_MAX]; |
530 | uschar *filename = NULL; | |
531 | size_t sz; | |
532 | uschar *exp_tls_dhparam; | |
533 | BOOL use_file_in_spool = FALSE; | |
534 | BOOL use_fixed_file = FALSE; | |
535 | host_item *host = NULL; /* dummy for macros */ | |
536 | ||
537 | DEBUG(D_tls) debug_printf("Initialising GnuTLS server params.\n"); | |
538 | ||
539 | rc = gnutls_dh_params_init(&dh_server_params); | |
2ea97746 | 540 | exim_gnutls_err_check(rc, US"gnutls_dh_params_init"); |
420a0d19 CE |
541 | |
542 | m.data = NULL; | |
543 | m.size = 0; | |
544 | ||
2ea97746 | 545 | if (!expand_check(tls_dhparam, US"tls_dhparam", &exp_tls_dhparam, errstr)) |
420a0d19 CE |
546 | return DEFER; |
547 | ||
548 | if (!exp_tls_dhparam) | |
549 | { | |
550 | DEBUG(D_tls) debug_printf("Loading default hard-coded DH params\n"); | |
551 | m.data = US std_dh_prime_default(); | |
552 | m.size = Ustrlen(m.data); | |
553 | } | |
554 | else if (Ustrcmp(exp_tls_dhparam, "historic") == 0) | |
555 | use_file_in_spool = TRUE; | |
556 | else if (Ustrcmp(exp_tls_dhparam, "none") == 0) | |
557 | { | |
558 | DEBUG(D_tls) debug_printf("Requested no DH parameters.\n"); | |
559 | return OK; | |
560 | } | |
561 | else if (exp_tls_dhparam[0] != '/') | |
562 | { | |
2ea97746 CE |
563 | if (!(m.data = US std_dh_prime_named(exp_tls_dhparam))) |
564 | return tls_error(US"No standard prime named", exp_tls_dhparam, NULL, errstr); | |
420a0d19 CE |
565 | m.size = Ustrlen(m.data); |
566 | } | |
567 | else | |
568 | { | |
569 | use_fixed_file = TRUE; | |
570 | filename = exp_tls_dhparam; | |
571 | } | |
572 | ||
573 | if (m.data) | |
574 | { | |
575 | rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM); | |
2ea97746 | 576 | exim_gnutls_err_check(rc, US"gnutls_dh_params_import_pkcs3"); |
420a0d19 CE |
577 | DEBUG(D_tls) debug_printf("Loaded fixed standard D-H parameters\n"); |
578 | return OK; | |
579 | } | |
580 | ||
581 | #ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS | |
582 | /* If you change this constant, also change dh_param_fn_ext so that we can use a | |
583 | different filename and ensure we have sufficient bits. */ | |
584 | dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, GNUTLS_SEC_PARAM_NORMAL); | |
585 | if (!dh_bits) | |
2ea97746 | 586 | return tls_error(US"gnutls_sec_param_to_pk_bits() failed", NULL, NULL, errstr); |
420a0d19 CE |
587 | DEBUG(D_tls) |
588 | debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits.\n", | |
589 | dh_bits); | |
590 | #else | |
591 | dh_bits = EXIM_SERVER_DH_BITS_PRE2_12; | |
592 | DEBUG(D_tls) | |
593 | debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits.\n", | |
594 | dh_bits); | |
595 | #endif | |
596 | ||
597 | /* Some clients have hard-coded limits. */ | |
598 | if (dh_bits > tls_dh_max_bits) | |
599 | { | |
600 | DEBUG(D_tls) | |
601 | debug_printf("tls_dh_max_bits clamping override, using %d bits instead.\n", | |
602 | tls_dh_max_bits); | |
603 | dh_bits = tls_dh_max_bits; | |
604 | } | |
605 | ||
606 | if (use_file_in_spool) | |
607 | { | |
608 | if (!string_format(filename_buf, sizeof(filename_buf), | |
609 | "%s/gnutls-params-%d", spool_directory, dh_bits)) | |
2ea97746 | 610 | return tls_error(US"overlong filename", NULL, NULL, errstr); |
420a0d19 CE |
611 | filename = filename_buf; |
612 | } | |
613 | ||
614 | /* Open the cache file for reading and if successful, read it and set up the | |
615 | parameters. */ | |
616 | ||
2ea97746 | 617 | if ((fd = Uopen(filename, O_RDONLY, 0)) >= 0) |
420a0d19 CE |
618 | { |
619 | struct stat statbuf; | |
620 | FILE *fp; | |
621 | int saved_errno; | |
622 | ||
623 | if (fstat(fd, &statbuf) < 0) /* EIO */ | |
624 | { | |
625 | saved_errno = errno; | |
626 | (void)close(fd); | |
2ea97746 | 627 | return tls_error(US"TLS cache stat failed", US strerror(saved_errno), NULL, errstr); |
420a0d19 CE |
628 | } |
629 | if (!S_ISREG(statbuf.st_mode)) | |
630 | { | |
631 | (void)close(fd); | |
2ea97746 | 632 | return tls_error(US"TLS cache not a file", NULL, NULL, errstr); |
420a0d19 | 633 | } |
2ea97746 | 634 | if (!(fp = fdopen(fd, "rb"))) |
420a0d19 CE |
635 | { |
636 | saved_errno = errno; | |
637 | (void)close(fd); | |
638 | return tls_error(US"fdopen(TLS cache stat fd) failed", | |
2ea97746 | 639 | US strerror(saved_errno), NULL, errstr); |
420a0d19 CE |
640 | } |
641 | ||
642 | m.size = statbuf.st_size; | |
2ea97746 | 643 | if (!(m.data = malloc(m.size))) |
420a0d19 CE |
644 | { |
645 | fclose(fp); | |
2ea97746 | 646 | return tls_error(US"malloc failed", US strerror(errno), NULL, errstr); |
420a0d19 | 647 | } |
2ea97746 | 648 | if (!(sz = fread(m.data, m.size, 1, fp))) |
420a0d19 CE |
649 | { |
650 | saved_errno = errno; | |
651 | fclose(fp); | |
652 | free(m.data); | |
2ea97746 | 653 | return tls_error(US"fread failed", US strerror(saved_errno), NULL, errstr); |
420a0d19 CE |
654 | } |
655 | fclose(fp); | |
656 | ||
657 | rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM); | |
658 | free(m.data); | |
2ea97746 | 659 | exim_gnutls_err_check(rc, US"gnutls_dh_params_import_pkcs3"); |
420a0d19 CE |
660 | DEBUG(D_tls) debug_printf("read D-H parameters from file \"%s\"\n", filename); |
661 | } | |
662 | ||
663 | /* If the file does not exist, fall through to compute new data and cache it. | |
664 | If there was any other opening error, it is serious. */ | |
665 | ||
666 | else if (errno == ENOENT) | |
667 | { | |
668 | rc = -1; | |
669 | DEBUG(D_tls) | |
670 | debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename); | |
671 | } | |
672 | else | |
673 | return tls_error(string_open_failed(errno, "\"%s\" for reading", filename), | |
2ea97746 | 674 | NULL, NULL, errstr); |
420a0d19 CE |
675 | |
676 | /* If ret < 0, either the cache file does not exist, or the data it contains | |
677 | is not useful. One particular case of this is when upgrading from an older | |
678 | release of Exim in which the data was stored in a different format. We don't | |
679 | try to be clever and support both formats; we just regenerate new data in this | |
680 | case. */ | |
681 | ||
682 | if (rc < 0) | |
683 | { | |
684 | uschar *temp_fn; | |
685 | unsigned int dh_bits_gen = dh_bits; | |
686 | ||
687 | if ((PATH_MAX - Ustrlen(filename)) < 10) | |
688 | return tls_error(US"Filename too long to generate replacement", | |
2ea97746 | 689 | filename, NULL, errstr); |
420a0d19 | 690 | |
2ea97746 CE |
691 | temp_fn = string_copy(US"%s.XXXXXXX"); |
692 | if ((fd = mkstemp(CS temp_fn)) < 0) /* modifies temp_fn */ | |
693 | return tls_error(US"Unable to open temp file", US strerror(errno), NULL, errstr); | |
420a0d19 CE |
694 | (void)fchown(fd, exim_uid, exim_gid); /* Probably not necessary */ |
695 | ||
696 | /* GnuTLS overshoots! | |
697 | * If we ask for 2236, we might get 2237 or more. | |
698 | * But there's no way to ask GnuTLS how many bits there really are. | |
699 | * We can ask how many bits were used in a TLS session, but that's it! | |
700 | * The prime itself is hidden behind too much abstraction. | |
701 | * So we ask for less, and proceed on a wing and a prayer. | |
702 | * First attempt, subtracted 3 for 2233 and got 2240. | |
703 | */ | |
704 | if (dh_bits >= EXIM_CLIENT_DH_MIN_BITS + 10) | |
705 | { | |
706 | dh_bits_gen = dh_bits - 10; | |
707 | DEBUG(D_tls) | |
708 | debug_printf("being paranoid about DH generation, make it '%d' bits'\n", | |
709 | dh_bits_gen); | |
710 | } | |
711 | ||
712 | DEBUG(D_tls) | |
713 | debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n", | |
714 | dh_bits_gen); | |
715 | rc = gnutls_dh_params_generate2(dh_server_params, dh_bits_gen); | |
2ea97746 | 716 | exim_gnutls_err_check(rc, US"gnutls_dh_params_generate2"); |
420a0d19 CE |
717 | |
718 | /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time, | |
719 | and I confirmed that a NULL call to get the size first is how the GnuTLS | |
720 | sample apps handle this. */ | |
721 | ||
722 | sz = 0; | |
723 | m.data = NULL; | |
724 | rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM, | |
725 | m.data, &sz); | |
726 | if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER) | |
2ea97746 | 727 | exim_gnutls_err_check(rc, US"gnutls_dh_params_export_pkcs3(NULL) sizing"); |
420a0d19 | 728 | m.size = sz; |
2ea97746 CE |
729 | if (!(m.data = malloc(m.size))) |
730 | return tls_error(US"memory allocation failed", US strerror(errno), NULL, errstr); | |
731 | ||
420a0d19 CE |
732 | /* this will return a size 1 less than the allocation size above */ |
733 | rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM, | |
734 | m.data, &sz); | |
735 | if (rc != GNUTLS_E_SUCCESS) | |
736 | { | |
737 | free(m.data); | |
2ea97746 | 738 | exim_gnutls_err_check(rc, US"gnutls_dh_params_export_pkcs3() real"); |
420a0d19 CE |
739 | } |
740 | m.size = sz; /* shrink by 1, probably */ | |
741 | ||
2ea97746 | 742 | if ((sz = write_to_fd_buf(fd, m.data, (size_t) m.size)) != m.size) |
420a0d19 CE |
743 | { |
744 | free(m.data); | |
745 | return tls_error(US"TLS cache write D-H params failed", | |
2ea97746 | 746 | US strerror(errno), NULL, errstr); |
420a0d19 CE |
747 | } |
748 | free(m.data); | |
2ea97746 | 749 | if ((sz = write_to_fd_buf(fd, US"\n", 1)) != 1) |
420a0d19 | 750 | return tls_error(US"TLS cache write D-H params final newline failed", |
2ea97746 | 751 | US strerror(errno), NULL, errstr); |
420a0d19 | 752 | |
2ea97746 CE |
753 | if ((rc = close(fd))) |
754 | return tls_error(US"TLS cache write close() failed", US strerror(errno), NULL, errstr); | |
420a0d19 CE |
755 | |
756 | if (Urename(temp_fn, filename) < 0) | |
757 | return tls_error(string_sprintf("failed to rename \"%s\" as \"%s\"", | |
2ea97746 | 758 | temp_fn, filename), US strerror(errno), NULL, errstr); |
420a0d19 CE |
759 | |
760 | DEBUG(D_tls) debug_printf("wrote D-H parameters to file \"%s\"\n", filename); | |
761 | } | |
762 | ||
763 | DEBUG(D_tls) debug_printf("initialized server D-H parameters\n"); | |
764 | return OK; | |
765 | } | |
766 | ||
767 | ||
768 | ||
769 | ||
2ea97746 CE |
770 | /* Create and install a selfsigned certificate, for use in server mode */ |
771 | ||
772 | static int | |
773 | tls_install_selfsign(exim_gnutls_state_st * state, uschar ** errstr) | |
774 | { | |
775 | gnutls_x509_crt_t cert = NULL; | |
776 | time_t now; | |
777 | gnutls_x509_privkey_t pkey = NULL; | |
778 | const uschar * where; | |
779 | int rc; | |
780 | ||
781 | where = US"initialising pkey"; | |
782 | if ((rc = gnutls_x509_privkey_init(&pkey))) goto err; | |
783 | ||
784 | where = US"initialising cert"; | |
785 | if ((rc = gnutls_x509_crt_init(&cert))) goto err; | |
786 | ||
787 | where = US"generating pkey"; | |
788 | if ((rc = gnutls_x509_privkey_generate(pkey, GNUTLS_PK_RSA, | |
789 | #ifdef SUPPORT_PARAM_TO_PK_BITS | |
790 | # ifndef GNUTLS_SEC_PARAM_MEDIUM | |
791 | # define GNUTLS_SEC_PARAM_MEDIUM GNUTLS_SEC_PARAM_HIGH | |
792 | # endif | |
793 | gnutls_sec_param_to_pk_bits(GNUTLS_PK_RSA, GNUTLS_SEC_PARAM_MEDIUM), | |
794 | #else | |
795 | 2048, | |
796 | #endif | |
797 | 0))) | |
798 | goto err; | |
799 | ||
800 | where = US"configuring cert"; | |
801 | now = 1; | |
802 | if ( (rc = gnutls_x509_crt_set_version(cert, 3)) | |
803 | || (rc = gnutls_x509_crt_set_serial(cert, &now, sizeof(now))) | |
804 | || (rc = gnutls_x509_crt_set_activation_time(cert, now = time(NULL))) | |
805 | || (rc = gnutls_x509_crt_set_expiration_time(cert, now + 60 * 60)) /* 1 hr */ | |
806 | || (rc = gnutls_x509_crt_set_key(cert, pkey)) | |
807 | ||
808 | || (rc = gnutls_x509_crt_set_dn_by_oid(cert, | |
809 | GNUTLS_OID_X520_COUNTRY_NAME, 0, "UK", 2)) | |
810 | || (rc = gnutls_x509_crt_set_dn_by_oid(cert, | |
811 | GNUTLS_OID_X520_ORGANIZATION_NAME, 0, "Exim Developers", 15)) | |
812 | || (rc = gnutls_x509_crt_set_dn_by_oid(cert, | |
813 | GNUTLS_OID_X520_COMMON_NAME, 0, | |
814 | smtp_active_hostname, Ustrlen(smtp_active_hostname))) | |
815 | ) | |
816 | goto err; | |
817 | ||
818 | where = US"signing cert"; | |
819 | if ((rc = gnutls_x509_crt_sign(cert, cert, pkey))) goto err; | |
820 | ||
821 | where = US"installing selfsign cert"; | |
822 | /* Since: 2.4.0 */ | |
823 | if ((rc = gnutls_certificate_set_x509_key(state->x509_cred, &cert, 1, pkey))) | |
824 | goto err; | |
825 | ||
826 | rc = OK; | |
827 | ||
828 | out: | |
829 | if (cert) gnutls_x509_crt_deinit(cert); | |
830 | if (pkey) gnutls_x509_privkey_deinit(pkey); | |
831 | return rc; | |
832 | ||
833 | err: | |
834 | rc = tls_error(where, US gnutls_strerror(rc), NULL, errstr); | |
835 | goto out; | |
836 | } | |
837 | ||
838 | ||
839 | ||
840 | ||
841 | /* Add certificate and key, from files. | |
842 | ||
843 | Return: | |
844 | Zero or negative: good. Negate value for certificate index if < 0. | |
845 | Greater than zero: FAIL or DEFER code. | |
846 | */ | |
847 | ||
848 | static int | |
849 | tls_add_certfile(exim_gnutls_state_st * state, const host_item * host, | |
850 | uschar * certfile, uschar * keyfile, uschar ** errstr) | |
851 | { | |
852 | int rc = gnutls_certificate_set_x509_key_file(state->x509_cred, | |
853 | CS certfile, CS keyfile, GNUTLS_X509_FMT_PEM); | |
854 | if (rc < 0) | |
855 | return tls_error( | |
856 | string_sprintf("cert/key setup: cert=%s key=%s", certfile, keyfile), | |
857 | US gnutls_strerror(rc), host, errstr); | |
858 | return -rc; | |
859 | } | |
860 | ||
861 | ||
420a0d19 CE |
862 | /************************************************* |
863 | * Variables re-expanded post-SNI * | |
864 | *************************************************/ | |
865 | ||
866 | /* Called from both server and client code, via tls_init(), and also from | |
867 | the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni". | |
868 | ||
869 | We can tell the two apart by state->received_sni being non-NULL in callback. | |
870 | ||
871 | The callback should not call us unless state->trigger_sni_changes is true, | |
872 | which we are responsible for setting on the first pass through. | |
873 | ||
874 | Arguments: | |
875 | state exim_gnutls_state_st * | |
2ea97746 | 876 | errstr error string pointer |
420a0d19 CE |
877 | |
878 | Returns: OK/DEFER/FAIL | |
879 | */ | |
880 | ||
881 | static int | |
2ea97746 | 882 | tls_expand_session_files(exim_gnutls_state_st * state, uschar ** errstr) |
420a0d19 CE |
883 | { |
884 | struct stat statbuf; | |
885 | int rc; | |
886 | const host_item *host = state->host; /* macro should be reconsidered? */ | |
887 | uschar *saved_tls_certificate = NULL; | |
888 | uschar *saved_tls_privatekey = NULL; | |
889 | uschar *saved_tls_verify_certificates = NULL; | |
890 | uschar *saved_tls_crl = NULL; | |
891 | int cert_count; | |
892 | ||
893 | /* We check for tls_sni *before* expansion. */ | |
894 | if (!host) /* server */ | |
420a0d19 CE |
895 | if (!state->received_sni) |
896 | { | |
2ea97746 CE |
897 | if ( state->tls_certificate |
898 | && ( Ustrstr(state->tls_certificate, US"tls_sni") | |
899 | || Ustrstr(state->tls_certificate, US"tls_in_sni") | |
900 | || Ustrstr(state->tls_certificate, US"tls_out_sni") | |
901 | ) ) | |
420a0d19 CE |
902 | { |
903 | DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI.\n"); | |
904 | state->trigger_sni_changes = TRUE; | |
905 | } | |
906 | } | |
907 | else | |
908 | { | |
909 | /* useful for debugging */ | |
910 | saved_tls_certificate = state->exp_tls_certificate; | |
911 | saved_tls_privatekey = state->exp_tls_privatekey; | |
912 | saved_tls_verify_certificates = state->exp_tls_verify_certificates; | |
913 | saved_tls_crl = state->exp_tls_crl; | |
914 | } | |
420a0d19 CE |
915 | |
916 | rc = gnutls_certificate_allocate_credentials(&state->x509_cred); | |
2ea97746 CE |
917 | exim_gnutls_err_check(rc, US"gnutls_certificate_allocate_credentials"); |
918 | ||
919 | #ifdef SUPPORT_SRV_OCSP_STACK | |
920 | gnutls_certificate_set_flags(state->x509_cred, GNUTLS_CERTIFICATE_API_V2); | |
921 | #endif | |
420a0d19 CE |
922 | |
923 | /* remember: expand_check_tlsvar() is expand_check() but fiddling with | |
924 | state members, assuming consistent naming; and expand_check() returns | |
925 | false if expansion failed, unless expansion was forced to fail. */ | |
926 | ||
927 | /* check if we at least have a certificate, before doing expensive | |
928 | D-H generation. */ | |
929 | ||
2ea97746 | 930 | if (!expand_check_tlsvar(tls_certificate, errstr)) |
420a0d19 CE |
931 | return DEFER; |
932 | ||
933 | /* certificate is mandatory in server, optional in client */ | |
934 | ||
2ea97746 CE |
935 | if ( !state->exp_tls_certificate |
936 | || !*state->exp_tls_certificate | |
937 | ) | |
420a0d19 | 938 | if (!host) |
2ea97746 | 939 | return tls_install_selfsign(state, errstr); |
420a0d19 CE |
940 | else |
941 | DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n"); | |
420a0d19 | 942 | |
2ea97746 | 943 | if (state->tls_privatekey && !expand_check_tlsvar(tls_privatekey, errstr)) |
420a0d19 CE |
944 | return DEFER; |
945 | ||
946 | /* tls_privatekey is optional, defaulting to same file as certificate */ | |
947 | ||
948 | if (state->tls_privatekey == NULL || *state->tls_privatekey == '\0') | |
949 | { | |
950 | state->tls_privatekey = state->tls_certificate; | |
951 | state->exp_tls_privatekey = state->exp_tls_certificate; | |
952 | } | |
953 | ||
954 | ||
955 | if (state->exp_tls_certificate && *state->exp_tls_certificate) | |
956 | { | |
957 | DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n", | |
958 | state->exp_tls_certificate, state->exp_tls_privatekey); | |
959 | ||
960 | if (state->received_sni) | |
2ea97746 CE |
961 | if ( Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0 |
962 | && Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0 | |
963 | ) | |
420a0d19 CE |
964 | { |
965 | DEBUG(D_tls) debug_printf("TLS SNI: cert and key unchanged\n"); | |
966 | } | |
967 | else | |
968 | { | |
969 | DEBUG(D_tls) debug_printf("TLS SNI: have a changed cert/key pair.\n"); | |
970 | } | |
420a0d19 | 971 | |
2ea97746 CE |
972 | if (!host) /* server */ |
973 | { | |
974 | const uschar * clist = state->exp_tls_certificate; | |
975 | const uschar * klist = state->exp_tls_privatekey; | |
976 | const uschar * olist; | |
977 | int csep = 0, ksep = 0, osep = 0, cnt = 0; | |
978 | uschar * cfile, * kfile, * ofile; | |
420a0d19 CE |
979 | |
980 | #ifndef DISABLE_OCSP | |
2ea97746 CE |
981 | if (!expand_check(tls_ocsp_file, US"tls_ocsp_file", &ofile, errstr)) |
982 | return DEFER; | |
983 | olist = ofile; | |
984 | #endif | |
420a0d19 | 985 | |
2ea97746 | 986 | while (cfile = string_nextinlist(&clist, &csep, NULL, 0)) |
420a0d19 | 987 | |
2ea97746 CE |
988 | if (!(kfile = string_nextinlist(&klist, &ksep, NULL, 0))) |
989 | return tls_error(US"cert/key setup: out of keys", NULL, host, errstr); | |
990 | else if (0 < (rc = tls_add_certfile(state, host, cfile, kfile, errstr))) | |
991 | return rc; | |
992 | else | |
993 | { | |
994 | int gnutls_cert_index = -rc; | |
995 | DEBUG(D_tls) debug_printf("TLS: cert/key %s registered\n", cfile); | |
420a0d19 | 996 | |
2ea97746 CE |
997 | /* Set the OCSP stapling server info */ |
998 | ||
999 | #ifndef DISABLE_OCSP | |
1000 | if (tls_ocsp_file) | |
1001 | if (gnutls_buggy_ocsp) | |
1002 | { | |
1003 | DEBUG(D_tls) | |
1004 | debug_printf("GnuTLS library is buggy for OCSP; avoiding\n"); | |
1005 | } | |
1006 | else if ((ofile = string_nextinlist(&olist, &osep, NULL, 0))) | |
1007 | { | |
1008 | /* Use the full callback method for stapling just to get | |
1009 | observability. More efficient would be to read the file once only, | |
1010 | if it never changed (due to SNI). Would need restart on file update, | |
1011 | or watch datestamp. */ | |
1012 | ||
1013 | # ifdef SUPPORT_SRV_OCSP_STACK | |
1014 | rc = gnutls_certificate_set_ocsp_status_request_function2( | |
1015 | state->x509_cred, gnutls_cert_index, | |
1016 | server_ocsp_stapling_cb, ofile); | |
1017 | ||
1018 | exim_gnutls_err_check(rc, | |
1019 | US"gnutls_certificate_set_ocsp_status_request_function2"); | |
1020 | # else | |
1021 | if (cnt++ > 0) | |
1022 | { | |
1023 | DEBUG(D_tls) | |
1024 | debug_printf("oops; multiple OCSP files not supported\n"); | |
1025 | break; | |
1026 | } | |
1027 | gnutls_certificate_set_ocsp_status_request_function( | |
1028 | state->x509_cred, server_ocsp_stapling_cb, ofile); | |
1029 | # endif | |
1030 | ||
1031 | DEBUG(D_tls) debug_printf("OCSP response file = %s\n", ofile); | |
1032 | } | |
1033 | else | |
1034 | DEBUG(D_tls) debug_printf("ran out of OCSP response files in list\n"); | |
420a0d19 | 1035 | #endif |
2ea97746 CE |
1036 | } |
1037 | } | |
1038 | else | |
1039 | { | |
1040 | if (0 < (rc = tls_add_certfile(state, host, | |
1041 | state->exp_tls_certificate, state->exp_tls_privatekey, errstr))) | |
1042 | return rc; | |
1043 | DEBUG(D_tls) debug_printf("TLS: cert/key registered\n"); | |
1044 | } | |
1045 | ||
1046 | } /* tls_certificate */ | |
420a0d19 CE |
1047 | |
1048 | ||
1049 | /* Set the trusted CAs file if one is provided, and then add the CRL if one is | |
1050 | provided. Experiment shows that, if the certificate file is empty, an unhelpful | |
1051 | error message is provided. However, if we just refrain from setting anything up | |
1052 | in that case, certificate verification fails, which seems to be the correct | |
1053 | behaviour. */ | |
1054 | ||
1055 | if (state->tls_verify_certificates && *state->tls_verify_certificates) | |
1056 | { | |
2ea97746 | 1057 | if (!expand_check_tlsvar(tls_verify_certificates, errstr)) |
420a0d19 | 1058 | return DEFER; |
2ea97746 CE |
1059 | #ifndef SUPPORT_SYSDEFAULT_CABUNDLE |
1060 | if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0) | |
1061 | state->exp_tls_verify_certificates = NULL; | |
1062 | #endif | |
420a0d19 | 1063 | if (state->tls_crl && *state->tls_crl) |
2ea97746 | 1064 | if (!expand_check_tlsvar(tls_crl, errstr)) |
420a0d19 CE |
1065 | return DEFER; |
1066 | ||
1067 | if (!(state->exp_tls_verify_certificates && | |
1068 | *state->exp_tls_verify_certificates)) | |
1069 | { | |
1070 | DEBUG(D_tls) | |
1071 | debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n"); | |
1072 | /* With no tls_verify_certificates, we ignore tls_crl too */ | |
1073 | return OK; | |
1074 | } | |
1075 | } | |
1076 | else | |
1077 | { | |
1078 | DEBUG(D_tls) | |
1079 | debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n"); | |
1080 | return OK; | |
1081 | } | |
1082 | ||
2ea97746 CE |
1083 | #ifdef SUPPORT_SYSDEFAULT_CABUNDLE |
1084 | if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0) | |
1085 | cert_count = gnutls_certificate_set_x509_system_trust(state->x509_cred); | |
1086 | else | |
1087 | #endif | |
420a0d19 | 1088 | { |
2ea97746 CE |
1089 | if (Ustat(state->exp_tls_verify_certificates, &statbuf) < 0) |
1090 | { | |
1091 | log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s " | |
1092 | "(tls_verify_certificates): %s", state->exp_tls_verify_certificates, | |
1093 | strerror(errno)); | |
1094 | return DEFER; | |
1095 | } | |
420a0d19 | 1096 | |
2ea97746 CE |
1097 | #ifndef SUPPORT_CA_DIR |
1098 | /* The test suite passes in /dev/null; we could check for that path explicitly, | |
1099 | but who knows if someone has some weird FIFO which always dumps some certs, or | |
1100 | other weirdness. The thing we really want to check is that it's not a | |
1101 | directory, since while OpenSSL supports that, GnuTLS does not. | |
1102 | So s/!S_ISREG/S_ISDIR/ and change some messaging ... */ | |
1103 | if (S_ISDIR(statbuf.st_mode)) | |
1104 | { | |
1105 | DEBUG(D_tls) | |
1106 | debug_printf("verify certificates path is a dir: \"%s\"\n", | |
1107 | state->exp_tls_verify_certificates); | |
1108 | log_write(0, LOG_MAIN|LOG_PANIC, | |
1109 | "tls_verify_certificates \"%s\" is a directory", | |
1110 | state->exp_tls_verify_certificates); | |
1111 | return DEFER; | |
1112 | } | |
1113 | #endif | |
420a0d19 | 1114 | |
2ea97746 CE |
1115 | DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n", |
1116 | state->exp_tls_verify_certificates, statbuf.st_size); | |
420a0d19 | 1117 | |
2ea97746 CE |
1118 | if (statbuf.st_size == 0) |
1119 | { | |
1120 | DEBUG(D_tls) | |
1121 | debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n"); | |
1122 | return OK; | |
1123 | } | |
1124 | ||
1125 | cert_count = | |
1126 | ||
1127 | #ifdef SUPPORT_CA_DIR | |
1128 | (statbuf.st_mode & S_IFMT) == S_IFDIR | |
1129 | ? | |
1130 | gnutls_certificate_set_x509_trust_dir(state->x509_cred, | |
1131 | CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM) | |
1132 | : | |
1133 | #endif | |
1134 | gnutls_certificate_set_x509_trust_file(state->x509_cred, | |
1135 | CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM); | |
420a0d19 CE |
1136 | } |
1137 | ||
420a0d19 CE |
1138 | if (cert_count < 0) |
1139 | { | |
1140 | rc = cert_count; | |
2ea97746 | 1141 | exim_gnutls_err_check(rc, US"setting certificate trust"); |
420a0d19 CE |
1142 | } |
1143 | DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n", cert_count); | |
1144 | ||
1145 | if (state->tls_crl && *state->tls_crl && | |
1146 | state->exp_tls_crl && *state->exp_tls_crl) | |
1147 | { | |
1148 | DEBUG(D_tls) debug_printf("loading CRL file = %s\n", state->exp_tls_crl); | |
1149 | cert_count = gnutls_certificate_set_x509_crl_file(state->x509_cred, | |
1150 | CS state->exp_tls_crl, GNUTLS_X509_FMT_PEM); | |
1151 | if (cert_count < 0) | |
1152 | { | |
1153 | rc = cert_count; | |
2ea97746 | 1154 | exim_gnutls_err_check(rc, US"gnutls_certificate_set_x509_crl_file"); |
420a0d19 CE |
1155 | } |
1156 | DEBUG(D_tls) debug_printf("Processed %d CRLs.\n", cert_count); | |
1157 | } | |
1158 | ||
1159 | return OK; | |
1160 | } | |
1161 | ||
1162 | ||
1163 | ||
1164 | ||
1165 | /************************************************* | |
1166 | * Set X.509 state variables * | |
1167 | *************************************************/ | |
1168 | ||
1169 | /* In GnuTLS, the registered cert/key are not replaced by a later | |
1170 | set of a cert/key, so for SNI support we need a whole new x509_cred | |
1171 | structure. Which means various other non-re-expanded pieces of state | |
1172 | need to be re-set in the new struct, so the setting logic is pulled | |
1173 | out to this. | |
1174 | ||
1175 | Arguments: | |
1176 | state exim_gnutls_state_st * | |
2ea97746 | 1177 | errstr error string pointer |
420a0d19 CE |
1178 | |
1179 | Returns: OK/DEFER/FAIL | |
1180 | */ | |
1181 | ||
1182 | static int | |
2ea97746 | 1183 | tls_set_remaining_x509(exim_gnutls_state_st *state, uschar ** errstr) |
420a0d19 CE |
1184 | { |
1185 | int rc; | |
1186 | const host_item *host = state->host; /* macro should be reconsidered? */ | |
1187 | ||
1188 | /* Create D-H parameters, or read them from the cache file. This function does | |
1189 | its own SMTP error messaging. This only happens for the server, TLS D-H ignores | |
1190 | client-side params. */ | |
1191 | ||
1192 | if (!state->host) | |
1193 | { | |
1194 | if (!dh_server_params) | |
1195 | { | |
2ea97746 | 1196 | rc = init_server_dh(errstr); |
420a0d19 CE |
1197 | if (rc != OK) return rc; |
1198 | } | |
1199 | gnutls_certificate_set_dh_params(state->x509_cred, dh_server_params); | |
1200 | } | |
1201 | ||
1202 | /* Link the credentials to the session. */ | |
1203 | ||
1204 | rc = gnutls_credentials_set(state->session, GNUTLS_CRD_CERTIFICATE, state->x509_cred); | |
2ea97746 | 1205 | exim_gnutls_err_check(rc, US"gnutls_credentials_set"); |
420a0d19 CE |
1206 | |
1207 | return OK; | |
1208 | } | |
1209 | ||
1210 | /************************************************* | |
1211 | * Initialize for GnuTLS * | |
1212 | *************************************************/ | |
1213 | ||
2ea97746 CE |
1214 | |
1215 | #ifndef DISABLE_OCSP | |
1216 | ||
1217 | static BOOL | |
1218 | tls_is_buggy_ocsp(void) | |
1219 | { | |
1220 | const uschar * s; | |
1221 | uschar maj, mid, mic; | |
1222 | ||
1223 | s = CUS gnutls_check_version(NULL); | |
1224 | maj = atoi(CCS s); | |
1225 | if (maj == 3) | |
1226 | { | |
1227 | while (*s && *s != '.') s++; | |
1228 | mid = atoi(CCS ++s); | |
1229 | if (mid <= 2) | |
1230 | return TRUE; | |
1231 | else if (mid >= 5) | |
1232 | return FALSE; | |
1233 | else | |
1234 | { | |
1235 | while (*s && *s != '.') s++; | |
1236 | mic = atoi(CCS ++s); | |
1237 | return mic <= (mid == 3 ? 16 : 3); | |
1238 | } | |
1239 | } | |
1240 | return FALSE; | |
1241 | } | |
1242 | ||
1243 | #endif | |
1244 | ||
1245 | ||
420a0d19 CE |
1246 | /* Called from both server and client code. In the case of a server, errors |
1247 | before actual TLS negotiation return DEFER. | |
1248 | ||
1249 | Arguments: | |
1250 | host connected host, if client; NULL if server | |
1251 | certificate certificate file | |
1252 | privatekey private key file | |
1253 | sni TLS SNI to send, sometimes when client; else NULL | |
1254 | cas CA certs file | |
1255 | crl CRL file | |
1256 | require_ciphers tls_require_ciphers setting | |
1257 | caller_state returned state-info structure | |
2ea97746 | 1258 | errstr error string pointer |
420a0d19 CE |
1259 | |
1260 | Returns: OK/DEFER/FAIL | |
1261 | */ | |
1262 | ||
1263 | static int | |
1264 | tls_init( | |
1265 | const host_item *host, | |
1266 | const uschar *certificate, | |
1267 | const uschar *privatekey, | |
1268 | const uschar *sni, | |
1269 | const uschar *cas, | |
1270 | const uschar *crl, | |
1271 | const uschar *require_ciphers, | |
2ea97746 CE |
1272 | exim_gnutls_state_st **caller_state, |
1273 | tls_support * tlsp, | |
1274 | uschar ** errstr) | |
420a0d19 CE |
1275 | { |
1276 | exim_gnutls_state_st *state; | |
1277 | int rc; | |
1278 | size_t sz; | |
1279 | const char *errpos; | |
1280 | uschar *p; | |
1281 | BOOL want_default_priorities; | |
1282 | ||
1283 | if (!exim_gnutls_base_init_done) | |
1284 | { | |
1285 | DEBUG(D_tls) debug_printf("GnuTLS global init required.\n"); | |
1286 | ||
1287 | #ifdef HAVE_GNUTLS_PKCS11 | |
1288 | /* By default, gnutls_global_init will init PKCS11 support in auto mode, | |
1289 | which loads modules from a config file, which sounds good and may be wanted | |
1290 | by some sysadmin, but also means in common configurations that GNOME keyring | |
1291 | environment variables are used and so breaks for users calling mailq. | |
1292 | To prevent this, we init PKCS11 first, which is the documented approach. */ | |
1293 | if (!gnutls_allow_auto_pkcs11) | |
1294 | { | |
1295 | rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL); | |
2ea97746 | 1296 | exim_gnutls_err_check(rc, US"gnutls_pkcs11_init"); |
420a0d19 CE |
1297 | } |
1298 | #endif | |
1299 | ||
1300 | rc = gnutls_global_init(); | |
2ea97746 | 1301 | exim_gnutls_err_check(rc, US"gnutls_global_init"); |
420a0d19 CE |
1302 | |
1303 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 | |
1304 | DEBUG(D_tls) | |
1305 | { | |
1306 | gnutls_global_set_log_function(exim_gnutls_logger_cb); | |
2ea97746 | 1307 | /* arbitrarily chosen level; bump up to 9 for more */ |
420a0d19 CE |
1308 | gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL); |
1309 | } | |
1310 | #endif | |
1311 | ||
2ea97746 CE |
1312 | #ifndef DISABLE_OCSP |
1313 | if (tls_ocsp_file && (gnutls_buggy_ocsp = tls_is_buggy_ocsp())) | |
1314 | log_write(0, LOG_MAIN, "OCSP unusable with this GnuTLS library version"); | |
1315 | #endif | |
1316 | ||
420a0d19 CE |
1317 | exim_gnutls_base_init_done = TRUE; |
1318 | } | |
1319 | ||
1320 | if (host) | |
1321 | { | |
2ea97746 CE |
1322 | /* For client-side sessions we allocate a context. This lets us run |
1323 | several in parallel. */ | |
1324 | int old_pool = store_pool; | |
1325 | store_pool = POOL_PERM; | |
1326 | state = store_get(sizeof(exim_gnutls_state_st)); | |
1327 | store_pool = old_pool; | |
1328 | ||
420a0d19 | 1329 | memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); |
2ea97746 | 1330 | state->tlsp = tlsp; |
420a0d19 CE |
1331 | DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n"); |
1332 | rc = gnutls_init(&state->session, GNUTLS_CLIENT); | |
1333 | } | |
1334 | else | |
1335 | { | |
1336 | state = &state_server; | |
1337 | memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); | |
2ea97746 | 1338 | state->tlsp = tlsp; |
420a0d19 CE |
1339 | DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n"); |
1340 | rc = gnutls_init(&state->session, GNUTLS_SERVER); | |
1341 | } | |
2ea97746 | 1342 | exim_gnutls_err_check(rc, US"gnutls_init"); |
420a0d19 CE |
1343 | |
1344 | state->host = host; | |
1345 | ||
1346 | state->tls_certificate = certificate; | |
1347 | state->tls_privatekey = privatekey; | |
1348 | state->tls_require_ciphers = require_ciphers; | |
1349 | state->tls_sni = sni; | |
1350 | state->tls_verify_certificates = cas; | |
1351 | state->tls_crl = crl; | |
1352 | ||
1353 | /* This handles the variables that might get re-expanded after TLS SNI; | |
1354 | that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */ | |
1355 | ||
1356 | DEBUG(D_tls) | |
1357 | debug_printf("Expanding various TLS configuration options for session credentials.\n"); | |
2ea97746 | 1358 | if ((rc = tls_expand_session_files(state, errstr)) != OK) return rc; |
420a0d19 CE |
1359 | |
1360 | /* These are all other parts of the x509_cred handling, since SNI in GnuTLS | |
1361 | requires a new structure afterwards. */ | |
1362 | ||
2ea97746 | 1363 | if ((rc = tls_set_remaining_x509(state, errstr)) != OK) return rc; |
420a0d19 CE |
1364 | |
1365 | /* set SNI in client, only */ | |
1366 | if (host) | |
1367 | { | |
2ea97746 | 1368 | if (!expand_check(sni, US"tls_out_sni", &state->tlsp->sni, errstr)) |
420a0d19 CE |
1369 | return DEFER; |
1370 | if (state->tlsp->sni && *state->tlsp->sni) | |
1371 | { | |
1372 | DEBUG(D_tls) | |
1373 | debug_printf("Setting TLS client SNI to \"%s\"\n", state->tlsp->sni); | |
1374 | sz = Ustrlen(state->tlsp->sni); | |
1375 | rc = gnutls_server_name_set(state->session, | |
1376 | GNUTLS_NAME_DNS, state->tlsp->sni, sz); | |
2ea97746 | 1377 | exim_gnutls_err_check(rc, US"gnutls_server_name_set"); |
420a0d19 CE |
1378 | } |
1379 | } | |
1380 | else if (state->tls_sni) | |
1381 | DEBUG(D_tls) debug_printf("*** PROBABLY A BUG *** " \ | |
2ea97746 | 1382 | "have an SNI set for a server [%s]\n", state->tls_sni); |
420a0d19 CE |
1383 | |
1384 | /* This is the priority string support, | |
1385 | http://www.gnutls.org/manual/html_node/Priority-Strings.html | |
1386 | and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols. | |
1387 | This was backwards incompatible, but means Exim no longer needs to track | |
1388 | all algorithms and provide string forms for them. */ | |
1389 | ||
1390 | want_default_priorities = TRUE; | |
1391 | ||
1392 | if (state->tls_require_ciphers && *state->tls_require_ciphers) | |
1393 | { | |
2ea97746 | 1394 | if (!expand_check_tlsvar(tls_require_ciphers, errstr)) |
420a0d19 CE |
1395 | return DEFER; |
1396 | if (state->exp_tls_require_ciphers && *state->exp_tls_require_ciphers) | |
1397 | { | |
1398 | DEBUG(D_tls) debug_printf("GnuTLS session cipher/priority \"%s\"\n", | |
1399 | state->exp_tls_require_ciphers); | |
1400 | ||
1401 | rc = gnutls_priority_init(&state->priority_cache, | |
1402 | CS state->exp_tls_require_ciphers, &errpos); | |
1403 | want_default_priorities = FALSE; | |
1404 | p = state->exp_tls_require_ciphers; | |
1405 | } | |
1406 | } | |
1407 | if (want_default_priorities) | |
1408 | { | |
1409 | DEBUG(D_tls) | |
1410 | debug_printf("GnuTLS using default session cipher/priority \"%s\"\n", | |
1411 | exim_default_gnutls_priority); | |
1412 | rc = gnutls_priority_init(&state->priority_cache, | |
1413 | exim_default_gnutls_priority, &errpos); | |
1414 | p = US exim_default_gnutls_priority; | |
1415 | } | |
1416 | ||
2ea97746 | 1417 | exim_gnutls_err_check(rc, string_sprintf( |
420a0d19 CE |
1418 | "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"", |
1419 | p, errpos - CS p, errpos)); | |
1420 | ||
1421 | rc = gnutls_priority_set(state->session, state->priority_cache); | |
2ea97746 | 1422 | exim_gnutls_err_check(rc, US"gnutls_priority_set"); |
420a0d19 CE |
1423 | |
1424 | gnutls_db_set_cache_expiration(state->session, ssl_session_timeout); | |
1425 | ||
1426 | /* Reduce security in favour of increased compatibility, if the admin | |
1427 | decides to make that trade-off. */ | |
1428 | if (gnutls_compat_mode) | |
1429 | { | |
1430 | #if LIBGNUTLS_VERSION_NUMBER >= 0x020104 | |
1431 | DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n"); | |
1432 | gnutls_session_enable_compatibility_mode(state->session); | |
1433 | #else | |
1434 | DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n"); | |
1435 | #endif | |
1436 | } | |
1437 | ||
1438 | *caller_state = state; | |
1439 | return OK; | |
1440 | } | |
1441 | ||
1442 | ||
1443 | ||
1444 | /************************************************* | |
1445 | * Extract peer information * | |
1446 | *************************************************/ | |
1447 | ||
1448 | /* Called from both server and client code. | |
1449 | Only this is allowed to set state->peerdn and state->have_set_peerdn | |
1450 | and we use that to detect double-calls. | |
1451 | ||
1452 | NOTE: the state blocks last while the TLS connection is up, which is fine | |
1453 | for logging in the server side, but for the client side, we log after teardown | |
1454 | in src/deliver.c. While the session is up, we can twist about states and | |
1455 | repoint tls_* globals, but those variables used for logging or other variable | |
1456 | expansion that happens _after_ delivery need to have a longer life-time. | |
1457 | ||
1458 | So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from | |
1459 | doing this more than once per generation of a state context. We set them in | |
1460 | the state context, and repoint tls_* to them. After the state goes away, the | |
1461 | tls_* copies of the pointers remain valid and client delivery logging is happy. | |
1462 | ||
1463 | tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues | |
1464 | don't apply. | |
1465 | ||
1466 | Arguments: | |
1467 | state exim_gnutls_state_st * | |
2ea97746 | 1468 | errstr pointer to error string |
420a0d19 CE |
1469 | |
1470 | Returns: OK/DEFER/FAIL | |
1471 | */ | |
1472 | ||
1473 | static int | |
2ea97746 | 1474 | peer_status(exim_gnutls_state_st *state, uschar ** errstr) |
420a0d19 CE |
1475 | { |
1476 | uschar cipherbuf[256]; | |
2ea97746 | 1477 | const gnutls_datum_t *cert_list; |
420a0d19 CE |
1478 | int old_pool, rc; |
1479 | unsigned int cert_list_size = 0; | |
1480 | gnutls_protocol_t protocol; | |
1481 | gnutls_cipher_algorithm_t cipher; | |
1482 | gnutls_kx_algorithm_t kx; | |
1483 | gnutls_mac_algorithm_t mac; | |
1484 | gnutls_certificate_type_t ct; | |
1485 | gnutls_x509_crt_t crt; | |
1486 | uschar *p, *dn_buf; | |
1487 | size_t sz; | |
1488 | ||
1489 | if (state->have_set_peerdn) | |
1490 | return OK; | |
1491 | state->have_set_peerdn = TRUE; | |
1492 | ||
1493 | state->peerdn = NULL; | |
1494 | ||
1495 | /* tls_cipher */ | |
1496 | cipher = gnutls_cipher_get(state->session); | |
1497 | protocol = gnutls_protocol_get_version(state->session); | |
1498 | mac = gnutls_mac_get(state->session); | |
1499 | kx = gnutls_kx_get(state->session); | |
1500 | ||
1501 | string_format(cipherbuf, sizeof(cipherbuf), | |
1502 | "%s:%s:%d", | |
1503 | gnutls_protocol_get_name(protocol), | |
1504 | gnutls_cipher_suite_get_name(kx, cipher, mac), | |
1505 | (int) gnutls_cipher_get_key_size(cipher) * 8); | |
1506 | ||
1507 | /* I don't see a way that spaces could occur, in the current GnuTLS | |
1508 | code base, but it was a concern in the old code and perhaps older GnuTLS | |
1509 | releases did return "TLS 1.0"; play it safe, just in case. */ | |
1510 | for (p = cipherbuf; *p != '\0'; ++p) | |
1511 | if (isspace(*p)) | |
1512 | *p = '-'; | |
1513 | old_pool = store_pool; | |
1514 | store_pool = POOL_PERM; | |
1515 | state->ciphersuite = string_copy(cipherbuf); | |
1516 | store_pool = old_pool; | |
1517 | state->tlsp->cipher = state->ciphersuite; | |
1518 | ||
1519 | /* tls_peerdn */ | |
1520 | cert_list = gnutls_certificate_get_peers(state->session, &cert_list_size); | |
1521 | ||
1522 | if (cert_list == NULL || cert_list_size == 0) | |
1523 | { | |
1524 | DEBUG(D_tls) debug_printf("TLS: no certificate from peer (%p & %d)\n", | |
1525 | cert_list, cert_list_size); | |
1526 | if (state->verify_requirement >= VERIFY_REQUIRED) | |
1527 | return tls_error(US"certificate verification failed", | |
2ea97746 | 1528 | US"no certificate received from peer", state->host, errstr); |
420a0d19 CE |
1529 | return OK; |
1530 | } | |
1531 | ||
1532 | ct = gnutls_certificate_type_get(state->session); | |
1533 | if (ct != GNUTLS_CRT_X509) | |
1534 | { | |
2ea97746 | 1535 | const uschar *ctn = US gnutls_certificate_type_get_name(ct); |
420a0d19 CE |
1536 | DEBUG(D_tls) |
1537 | debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn); | |
1538 | if (state->verify_requirement >= VERIFY_REQUIRED) | |
1539 | return tls_error(US"certificate verification not possible, unhandled type", | |
2ea97746 | 1540 | ctn, state->host, errstr); |
420a0d19 CE |
1541 | return OK; |
1542 | } | |
1543 | ||
1544 | #define exim_gnutls_peer_err(Label) \ | |
1545 | do { \ | |
1546 | if (rc != GNUTLS_E_SUCCESS) \ | |
1547 | { \ | |
1548 | DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \ | |
1549 | (Label), gnutls_strerror(rc)); \ | |
1550 | if (state->verify_requirement >= VERIFY_REQUIRED) \ | |
2ea97746 | 1551 | return tls_error((Label), US gnutls_strerror(rc), state->host, errstr); \ |
420a0d19 CE |
1552 | return OK; \ |
1553 | } \ | |
1554 | } while (0) | |
1555 | ||
1556 | rc = import_cert(&cert_list[0], &crt); | |
1557 | exim_gnutls_peer_err(US"cert 0"); | |
1558 | ||
1559 | state->tlsp->peercert = state->peercert = crt; | |
1560 | ||
1561 | sz = 0; | |
1562 | rc = gnutls_x509_crt_get_dn(crt, NULL, &sz); | |
1563 | if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER) | |
1564 | { | |
1565 | exim_gnutls_peer_err(US"getting size for cert DN failed"); | |
1566 | return FAIL; /* should not happen */ | |
1567 | } | |
1568 | dn_buf = store_get_perm(sz); | |
1569 | rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz); | |
1570 | exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]"); | |
1571 | ||
1572 | state->peerdn = dn_buf; | |
1573 | ||
1574 | return OK; | |
1575 | #undef exim_gnutls_peer_err | |
1576 | } | |
1577 | ||
1578 | ||
1579 | ||
1580 | ||
1581 | /************************************************* | |
1582 | * Verify peer certificate * | |
1583 | *************************************************/ | |
1584 | ||
1585 | /* Called from both server and client code. | |
1586 | *Should* be using a callback registered with | |
1587 | gnutls_certificate_set_verify_function() to fail the handshake if we dislike | |
1588 | the peer information, but that's too new for some OSes. | |
1589 | ||
1590 | Arguments: | |
2ea97746 CE |
1591 | state exim_gnutls_state_st * |
1592 | errstr where to put an error message | |
420a0d19 CE |
1593 | |
1594 | Returns: | |
1595 | FALSE if the session should be rejected | |
1596 | TRUE if the cert is okay or we just don't care | |
1597 | */ | |
1598 | ||
1599 | static BOOL | |
2ea97746 | 1600 | verify_certificate(exim_gnutls_state_st * state, uschar ** errstr) |
420a0d19 CE |
1601 | { |
1602 | int rc; | |
2ea97746 CE |
1603 | uint verify; |
1604 | ||
1605 | if (state->verify_requirement == VERIFY_NONE) | |
1606 | return TRUE; | |
420a0d19 | 1607 | |
2ea97746 CE |
1608 | DEBUG(D_tls) debug_printf("TLS: checking peer certificate\n"); |
1609 | *errstr = NULL; | |
420a0d19 | 1610 | |
2ea97746 | 1611 | if ((rc = peer_status(state, errstr)) != OK) |
420a0d19 CE |
1612 | { |
1613 | verify = GNUTLS_CERT_INVALID; | |
2ea97746 | 1614 | *errstr = US"certificate not supplied"; |
420a0d19 CE |
1615 | } |
1616 | else | |
2ea97746 CE |
1617 | |
1618 | { | |
1619 | #ifdef SUPPORT_DANE | |
1620 | if (state->verify_requirement == VERIFY_DANE && state->host) | |
1621 | { | |
1622 | /* Using dane_verify_session_crt() would be easy, as it does it all for us | |
1623 | including talking to a DNS resolver. But we want to do that bit ourselves | |
1624 | as the testsuite intercepts and fakes its own DNS environment. */ | |
1625 | ||
1626 | dane_state_t s; | |
1627 | dane_query_t r; | |
1628 | uint lsize; | |
1629 | const gnutls_datum_t * certlist = | |
1630 | gnutls_certificate_get_peers(state->session, &lsize); | |
1631 | int usage = tls_out.tlsa_usage; | |
1632 | ||
1633 | # ifdef GNUTLS_BROKEN_DANE_VALIDATION | |
1634 | /* Split the TLSA records into two sets, TA and EE selectors. Run the | |
1635 | dane-verification separately so that we know which selector verified; | |
1636 | then we know whether to do name-verification (needed for TA but not EE). */ | |
1637 | ||
1638 | if (usage == ((1<<DANESSL_USAGE_DANE_TA) | (1<<DANESSL_USAGE_DANE_EE))) | |
1639 | { /* a mixed-usage bundle */ | |
1640 | int i, j, nrec; | |
1641 | const char ** dd; | |
1642 | int * ddl; | |
1643 | ||
1644 | for(nrec = 0; state->dane_data_len[nrec]; ) nrec++; | |
1645 | nrec++; | |
1646 | ||
1647 | dd = store_get(nrec * sizeof(uschar *)); | |
1648 | ddl = store_get(nrec * sizeof(int)); | |
1649 | nrec--; | |
1650 | ||
1651 | if ((rc = dane_state_init(&s, 0))) | |
1652 | goto tlsa_prob; | |
1653 | ||
1654 | for (usage = DANESSL_USAGE_DANE_EE; | |
1655 | usage >= DANESSL_USAGE_DANE_TA; usage--) | |
1656 | { /* take records with this usage */ | |
1657 | for (j = i = 0; i < nrec; i++) | |
1658 | if (state->dane_data[i][0] == usage) | |
1659 | { | |
1660 | dd[j] = state->dane_data[i]; | |
1661 | ddl[j++] = state->dane_data_len[i]; | |
1662 | } | |
1663 | if (j) | |
1664 | { | |
1665 | dd[j] = NULL; | |
1666 | ddl[j] = 0; | |
1667 | ||
1668 | if ((rc = dane_raw_tlsa(s, &r, (char * const *)dd, ddl, 1, 0))) | |
1669 | goto tlsa_prob; | |
1670 | ||
1671 | if ((rc = dane_verify_crt_raw(s, certlist, lsize, | |
1672 | gnutls_certificate_type_get(state->session), | |
1673 | r, 0, | |
1674 | usage == DANESSL_USAGE_DANE_EE | |
1675 | ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0, | |
1676 | &verify))) | |
1677 | { | |
1678 | DEBUG(D_tls) | |
1679 | debug_printf("TLSA record problem: %s\n", dane_strerror(rc)); | |
1680 | } | |
1681 | else if (verify == 0) /* verification passed */ | |
1682 | { | |
1683 | usage = 1 << usage; | |
1684 | break; | |
1685 | } | |
1686 | } | |
1687 | } | |
1688 | ||
1689 | if (rc) goto tlsa_prob; | |
1690 | } | |
1691 | else | |
1692 | # endif | |
1693 | { | |
1694 | if ( (rc = dane_state_init(&s, 0)) | |
1695 | || (rc = dane_raw_tlsa(s, &r, state->dane_data, state->dane_data_len, | |
1696 | 1, 0)) | |
1697 | || (rc = dane_verify_crt_raw(s, certlist, lsize, | |
1698 | gnutls_certificate_type_get(state->session), | |
1699 | r, 0, | |
1700 | # ifdef GNUTLS_BROKEN_DANE_VALIDATION | |
1701 | usage == (1 << DANESSL_USAGE_DANE_EE) | |
1702 | ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0, | |
1703 | # else | |
1704 | 0, | |
1705 | # endif | |
1706 | &verify)) | |
1707 | ) | |
1708 | goto tlsa_prob; | |
1709 | } | |
1710 | ||
1711 | if (verify != 0) /* verification failed */ | |
1712 | { | |
1713 | gnutls_datum_t str; | |
1714 | (void) dane_verification_status_print(verify, &str, 0); | |
1715 | *errstr = US str.data; /* don't bother to free */ | |
1716 | goto badcert; | |
1717 | } | |
1718 | ||
1719 | # ifdef GNUTLS_BROKEN_DANE_VALIDATION | |
1720 | /* If a TA-mode TLSA record was used for verification we must additionally | |
1721 | verify the cert name (but not the CA chain). For EE-mode, skip it. */ | |
1722 | ||
1723 | if (usage & (1 << DANESSL_USAGE_DANE_EE)) | |
1724 | # endif | |
1725 | { | |
1726 | state->peer_dane_verified = state->peer_cert_verified = TRUE; | |
1727 | goto goodcert; | |
1728 | } | |
1729 | # ifdef GNUTLS_BROKEN_DANE_VALIDATION | |
1730 | /* Assume that the name on the A-record is the one that should be matching | |
1731 | the cert. An alternate view is that the domain part of the email address | |
1732 | is also permissible. */ | |
1733 | ||
1734 | if (gnutls_x509_crt_check_hostname(state->tlsp->peercert, | |
1735 | CS state->host->name)) | |
1736 | { | |
1737 | state->peer_dane_verified = state->peer_cert_verified = TRUE; | |
1738 | goto goodcert; | |
1739 | } | |
1740 | # endif | |
1741 | } | |
1742 | #endif /*SUPPORT_DANE*/ | |
1743 | ||
420a0d19 | 1744 | rc = gnutls_certificate_verify_peers2(state->session, &verify); |
2ea97746 | 1745 | } |
420a0d19 | 1746 | |
2ea97746 | 1747 | /* Handle the result of verification. INVALID is set if any others are. */ |
420a0d19 | 1748 | |
2ea97746 | 1749 | if (rc < 0 || verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED)) |
420a0d19 CE |
1750 | { |
1751 | state->peer_cert_verified = FALSE; | |
2ea97746 CE |
1752 | if (!*errstr) |
1753 | { | |
1754 | #ifdef GNUTLS_CERT_VFY_STATUS_PRINT | |
1755 | DEBUG(D_tls) | |
1756 | { | |
1757 | gnutls_datum_t txt; | |
1758 | ||
1759 | if (gnutls_certificate_verification_status_print(verify, | |
1760 | gnutls_certificate_type_get(state->session), &txt, 0) | |
1761 | == GNUTLS_E_SUCCESS) | |
1762 | { | |
1763 | debug_printf("%s\n", txt.data); | |
1764 | gnutls_free(txt.data); | |
1765 | } | |
1766 | } | |
1767 | #endif | |
1768 | *errstr = verify & GNUTLS_CERT_REVOKED | |
1769 | ? US"certificate revoked" : US"certificate invalid"; | |
1770 | } | |
420a0d19 CE |
1771 | |
1772 | DEBUG(D_tls) | |
1773 | debug_printf("TLS certificate verification failed (%s): peerdn=\"%s\"\n", | |
2ea97746 | 1774 | *errstr, state->peerdn ? state->peerdn : US"<unset>"); |
420a0d19 CE |
1775 | |
1776 | if (state->verify_requirement >= VERIFY_REQUIRED) | |
2ea97746 | 1777 | goto badcert; |
420a0d19 CE |
1778 | DEBUG(D_tls) |
1779 | debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n"); | |
1780 | } | |
1781 | ||
1782 | else | |
1783 | { | |
2ea97746 CE |
1784 | /* Client side, check the server's certificate name versus the name on the |
1785 | A-record for the connection we made. What to do for server side - what name | |
1786 | to use for client? We document that there is no such checking for server | |
1787 | side. */ | |
1788 | ||
1789 | if ( state->exp_tls_verify_cert_hostnames | |
1790 | && !gnutls_x509_crt_check_hostname(state->tlsp->peercert, | |
1791 | CS state->exp_tls_verify_cert_hostnames) | |
1792 | ) | |
420a0d19 | 1793 | { |
2ea97746 CE |
1794 | DEBUG(D_tls) |
1795 | debug_printf("TLS certificate verification failed: cert name mismatch\n"); | |
1796 | if (state->verify_requirement >= VERIFY_REQUIRED) | |
1797 | goto badcert; | |
1798 | return TRUE; | |
420a0d19 | 1799 | } |
2ea97746 | 1800 | |
420a0d19 CE |
1801 | state->peer_cert_verified = TRUE; |
1802 | DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=\"%s\"\n", | |
1803 | state->peerdn ? state->peerdn : US"<unset>"); | |
1804 | } | |
1805 | ||
2ea97746 CE |
1806 | goodcert: |
1807 | state->tlsp->peerdn = state->peerdn; | |
1808 | return TRUE; | |
420a0d19 | 1809 | |
2ea97746 CE |
1810 | #ifdef SUPPORT_DANE |
1811 | tlsa_prob: | |
1812 | *errstr = string_sprintf("TLSA record problem: %s", | |
1813 | rc == DANE_E_REQUESTED_DATA_NOT_AVAILABLE ? "none usable" : dane_strerror(rc)); | |
1814 | #endif | |
1815 | ||
1816 | badcert: | |
1817 | gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE); | |
1818 | return FALSE; | |
420a0d19 CE |
1819 | } |
1820 | ||
1821 | ||
1822 | ||
1823 | ||
1824 | /* ------------------------------------------------------------------------ */ | |
1825 | /* Callbacks */ | |
1826 | ||
1827 | /* Logging function which can be registered with | |
1828 | * gnutls_global_set_log_function() | |
1829 | * gnutls_global_set_log_level() 0..9 | |
1830 | */ | |
1831 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 | |
1832 | static void | |
1833 | exim_gnutls_logger_cb(int level, const char *message) | |
1834 | { | |
1835 | size_t len = strlen(message); | |
1836 | if (len < 1) | |
1837 | { | |
1838 | DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level); | |
1839 | return; | |
1840 | } | |
1841 | DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message, | |
1842 | message[len-1] == '\n' ? "" : "\n"); | |
1843 | } | |
1844 | #endif | |
1845 | ||
1846 | ||
1847 | /* Called after client hello, should handle SNI work. | |
1848 | This will always set tls_sni (state->received_sni) if available, | |
1849 | and may trigger presenting different certificates, | |
1850 | if state->trigger_sni_changes is TRUE. | |
1851 | ||
1852 | Should be registered with | |
1853 | gnutls_handshake_set_post_client_hello_function() | |
1854 | ||
1855 | "This callback must return 0 on success or a gnutls error code to terminate the | |
1856 | handshake.". | |
1857 | ||
1858 | For inability to get SNI information, we return 0. | |
1859 | We only return non-zero if re-setup failed. | |
1860 | Only used for server-side TLS. | |
1861 | */ | |
1862 | ||
1863 | static int | |
1864 | exim_sni_handling_cb(gnutls_session_t session) | |
1865 | { | |
1866 | char sni_name[MAX_HOST_LEN]; | |
1867 | size_t data_len = MAX_HOST_LEN; | |
1868 | exim_gnutls_state_st *state = &state_server; | |
1869 | unsigned int sni_type; | |
1870 | int rc, old_pool; | |
2ea97746 | 1871 | uschar * dummy_errstr; |
420a0d19 CE |
1872 | |
1873 | rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0); | |
1874 | if (rc != GNUTLS_E_SUCCESS) | |
1875 | { | |
1876 | DEBUG(D_tls) { | |
1877 | if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) | |
1878 | debug_printf("TLS: no SNI presented in handshake.\n"); | |
1879 | else | |
1880 | debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n", | |
1881 | gnutls_strerror(rc), rc); | |
2ea97746 | 1882 | } |
420a0d19 CE |
1883 | return 0; |
1884 | } | |
1885 | ||
1886 | if (sni_type != GNUTLS_NAME_DNS) | |
1887 | { | |
1888 | DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type); | |
1889 | return 0; | |
1890 | } | |
1891 | ||
1892 | /* We now have a UTF-8 string in sni_name */ | |
1893 | old_pool = store_pool; | |
1894 | store_pool = POOL_PERM; | |
1895 | state->received_sni = string_copyn(US sni_name, data_len); | |
1896 | store_pool = old_pool; | |
1897 | ||
1898 | /* We set this one now so that variable expansions below will work */ | |
1899 | state->tlsp->sni = state->received_sni; | |
1900 | ||
1901 | DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name, | |
1902 | state->trigger_sni_changes ? "" : " (unused for certificate selection)"); | |
1903 | ||
1904 | if (!state->trigger_sni_changes) | |
1905 | return 0; | |
1906 | ||
2ea97746 | 1907 | if ((rc = tls_expand_session_files(state, &dummy_errstr)) != OK) |
420a0d19 CE |
1908 | { |
1909 | /* If the setup of certs/etc failed before handshake, TLS would not have | |
1910 | been offered. The best we can do now is abort. */ | |
1911 | return GNUTLS_E_APPLICATION_ERROR_MIN; | |
1912 | } | |
1913 | ||
2ea97746 | 1914 | rc = tls_set_remaining_x509(state, &dummy_errstr); |
420a0d19 CE |
1915 | if (rc != OK) return GNUTLS_E_APPLICATION_ERROR_MIN; |
1916 | ||
1917 | return 0; | |
1918 | } | |
1919 | ||
1920 | ||
1921 | ||
1922 | #ifndef DISABLE_OCSP | |
1923 | ||
1924 | static int | |
1925 | server_ocsp_stapling_cb(gnutls_session_t session, void * ptr, | |
1926 | gnutls_datum_t * ocsp_response) | |
1927 | { | |
1928 | int ret; | |
2ea97746 | 1929 | DEBUG(D_tls) debug_printf("OCSP stapling callback: %s\n", US ptr); |
420a0d19 CE |
1930 | |
1931 | if ((ret = gnutls_load_file(ptr, ocsp_response)) < 0) | |
1932 | { | |
1933 | DEBUG(D_tls) debug_printf("Failed to load ocsp stapling file %s\n", | |
2ea97746 | 1934 | CS ptr); |
420a0d19 CE |
1935 | tls_in.ocsp = OCSP_NOT_RESP; |
1936 | return GNUTLS_E_NO_CERTIFICATE_STATUS; | |
1937 | } | |
1938 | ||
1939 | tls_in.ocsp = OCSP_VFY_NOT_TRIED; | |
1940 | return 0; | |
1941 | } | |
1942 | ||
1943 | #endif | |
1944 | ||
1945 | ||
2ea97746 CE |
1946 | #ifndef DISABLE_EVENT |
1947 | /* | |
1948 | We use this callback to get observability and detail-level control | |
1949 | for an exim TLS connection (either direction), raising a tls:cert event | |
1950 | for each cert in the chain presented by the peer. Any event | |
1951 | can deny verification. | |
1952 | ||
1953 | Return 0 for the handshake to continue or non-zero to terminate. | |
1954 | */ | |
1955 | ||
1956 | static int | |
1957 | verify_cb(gnutls_session_t session) | |
1958 | { | |
1959 | const gnutls_datum_t * cert_list; | |
1960 | unsigned int cert_list_size = 0; | |
1961 | gnutls_x509_crt_t crt; | |
1962 | int rc; | |
1963 | uschar * yield; | |
1964 | exim_gnutls_state_st * state = gnutls_session_get_ptr(session); | |
1965 | ||
1966 | if ((cert_list = gnutls_certificate_get_peers(session, &cert_list_size))) | |
1967 | while (cert_list_size--) | |
1968 | { | |
1969 | if ((rc = import_cert(&cert_list[cert_list_size], &crt)) != GNUTLS_E_SUCCESS) | |
1970 | { | |
1971 | DEBUG(D_tls) debug_printf("TLS: peer cert problem: depth %d: %s\n", | |
1972 | cert_list_size, gnutls_strerror(rc)); | |
1973 | break; | |
1974 | } | |
1975 | ||
1976 | state->tlsp->peercert = crt; | |
1977 | if ((yield = event_raise(state->event_action, | |
1978 | US"tls:cert", string_sprintf("%d", cert_list_size)))) | |
1979 | { | |
1980 | log_write(0, LOG_MAIN, | |
1981 | "SSL verify denied by event-action: depth=%d: %s", | |
1982 | cert_list_size, yield); | |
1983 | return 1; /* reject */ | |
1984 | } | |
1985 | state->tlsp->peercert = NULL; | |
1986 | } | |
1987 | ||
1988 | return 0; | |
1989 | } | |
1990 | ||
1991 | #endif | |
420a0d19 CE |
1992 | |
1993 | ||
1994 | ||
1995 | /* ------------------------------------------------------------------------ */ | |
1996 | /* Exported functions */ | |
1997 | ||
1998 | ||
1999 | ||
2000 | ||
2001 | /************************************************* | |
2002 | * Start a TLS session in a server * | |
2003 | *************************************************/ | |
2004 | ||
2005 | /* This is called when Exim is running as a server, after having received | |
2006 | the STARTTLS command. It must respond to that command, and then negotiate | |
2007 | a TLS session. | |
2008 | ||
2009 | Arguments: | |
2010 | require_ciphers list of allowed ciphers or NULL | |
2ea97746 | 2011 | errstr pointer to error string |
420a0d19 CE |
2012 | |
2013 | Returns: OK on success | |
2014 | DEFER for errors before the start of the negotiation | |
2ea97746 | 2015 | FAIL for errors during the negotiation; the server can't |
420a0d19 CE |
2016 | continue running. |
2017 | */ | |
2018 | ||
2019 | int | |
2ea97746 | 2020 | tls_server_start(const uschar * require_ciphers, uschar ** errstr) |
420a0d19 CE |
2021 | { |
2022 | int rc; | |
2ea97746 | 2023 | exim_gnutls_state_st * state = NULL; |
420a0d19 CE |
2024 | |
2025 | /* Check for previous activation */ | |
2ea97746 | 2026 | if (tls_in.active.sock >= 0) |
420a0d19 | 2027 | { |
2ea97746 CE |
2028 | tls_error(US"STARTTLS received after TLS started", US "", NULL, errstr); |
2029 | smtp_printf("554 Already in TLS\r\n", FALSE); | |
420a0d19 CE |
2030 | return FAIL; |
2031 | } | |
2032 | ||
2033 | /* Initialize the library. If it fails, it will already have logged the error | |
2034 | and sent an SMTP response. */ | |
2035 | ||
2036 | DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n"); | |
2037 | ||
2ea97746 | 2038 | if ((rc = tls_init(NULL, tls_certificate, tls_privatekey, |
420a0d19 | 2039 | NULL, tls_verify_certificates, tls_crl, |
2ea97746 | 2040 | require_ciphers, &state, &tls_in, errstr)) != OK) return rc; |
420a0d19 CE |
2041 | |
2042 | /* If this is a host for which certificate verification is mandatory or | |
2043 | optional, set up appropriately. */ | |
2044 | ||
2045 | if (verify_check_host(&tls_verify_hosts) == OK) | |
2046 | { | |
2047 | DEBUG(D_tls) | |
2048 | debug_printf("TLS: a client certificate will be required.\n"); | |
2049 | state->verify_requirement = VERIFY_REQUIRED; | |
2050 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE); | |
2051 | } | |
2052 | else if (verify_check_host(&tls_try_verify_hosts) == OK) | |
2053 | { | |
2054 | DEBUG(D_tls) | |
2055 | debug_printf("TLS: a client certificate will be requested but not required.\n"); | |
2056 | state->verify_requirement = VERIFY_OPTIONAL; | |
2057 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST); | |
2058 | } | |
2059 | else | |
2060 | { | |
2061 | DEBUG(D_tls) | |
2062 | debug_printf("TLS: a client certificate will not be requested.\n"); | |
2063 | state->verify_requirement = VERIFY_NONE; | |
2064 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE); | |
2065 | } | |
2066 | ||
2ea97746 CE |
2067 | #ifndef DISABLE_EVENT |
2068 | if (event_action) | |
2069 | { | |
2070 | state->event_action = event_action; | |
2071 | gnutls_session_set_ptr(state->session, state); | |
2072 | gnutls_certificate_set_verify_function(state->x509_cred, verify_cb); | |
2073 | } | |
2074 | #endif | |
2075 | ||
420a0d19 CE |
2076 | /* Register SNI handling; always, even if not in tls_certificate, so that the |
2077 | expansion variable $tls_sni is always available. */ | |
2078 | ||
2079 | gnutls_handshake_set_post_client_hello_function(state->session, | |
2080 | exim_sni_handling_cb); | |
2081 | ||
2082 | /* Set context and tell client to go ahead, except in the case of TLS startup | |
2083 | on connection, where outputting anything now upsets the clients and tends to | |
2084 | make them disconnect. We need to have an explicit fflush() here, to force out | |
2085 | the response. Other smtp_printf() calls do not need it, because in non-TLS | |
2086 | mode, the fflush() happens when smtp_getc() is called. */ | |
2087 | ||
2088 | if (!state->tlsp->on_connect) | |
2089 | { | |
2ea97746 | 2090 | smtp_printf("220 TLS go ahead\r\n", FALSE); |
420a0d19 CE |
2091 | fflush(smtp_out); |
2092 | } | |
2093 | ||
2094 | /* Now negotiate the TLS session. We put our own timer on it, since it seems | |
2ea97746 CE |
2095 | that the GnuTLS library doesn't. |
2096 | From 3.1.0 there is gnutls_handshake_set_timeout() - but it requires you | |
2097 | to set (and clear down afterwards) up a pull-timeout callback function that does | |
2098 | a select, so we're no better off unless avoiding signals becomes an issue. */ | |
420a0d19 CE |
2099 | |
2100 | gnutls_transport_set_ptr2(state->session, | |
2ea97746 CE |
2101 | (gnutls_transport_ptr_t)(long) fileno(smtp_in), |
2102 | (gnutls_transport_ptr_t)(long) fileno(smtp_out)); | |
420a0d19 CE |
2103 | state->fd_in = fileno(smtp_in); |
2104 | state->fd_out = fileno(smtp_out); | |
2105 | ||
2106 | sigalrm_seen = FALSE; | |
2ea97746 | 2107 | if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout); |
420a0d19 | 2108 | do |
420a0d19 | 2109 | rc = gnutls_handshake(state->session); |
2ea97746 CE |
2110 | while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen); |
2111 | ALARM_CLR(0); | |
420a0d19 CE |
2112 | |
2113 | if (rc != GNUTLS_E_SUCCESS) | |
2114 | { | |
420a0d19 CE |
2115 | /* It seems that, except in the case of a timeout, we have to close the |
2116 | connection right here; otherwise if the other end is running OpenSSL it hangs | |
2117 | until the server times out. */ | |
2118 | ||
2ea97746 | 2119 | if (sigalrm_seen) |
420a0d19 | 2120 | { |
2ea97746 CE |
2121 | tls_error(US"gnutls_handshake", US"timed out", NULL, errstr); |
2122 | gnutls_db_remove_session(state->session); | |
2123 | } | |
2124 | else | |
2125 | { | |
2126 | tls_error(US"gnutls_handshake", US gnutls_strerror(rc), NULL, errstr); | |
2127 | (void) gnutls_alert_send_appropriate(state->session, rc); | |
2128 | gnutls_deinit(state->session); | |
2129 | gnutls_certificate_free_credentials(state->x509_cred); | |
2130 | millisleep(500); | |
2131 | shutdown(state->fd_out, SHUT_WR); | |
2132 | for (rc = 1024; fgetc(smtp_in) != EOF && rc > 0; ) rc--; /* drain skt */ | |
420a0d19 CE |
2133 | (void)fclose(smtp_out); |
2134 | (void)fclose(smtp_in); | |
2ea97746 | 2135 | smtp_out = smtp_in = NULL; |
420a0d19 CE |
2136 | } |
2137 | ||
2138 | return FAIL; | |
2139 | } | |
2140 | ||
2141 | DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n"); | |
2142 | ||
2143 | /* Verify after the fact */ | |
2144 | ||
2ea97746 | 2145 | if (!verify_certificate(state, errstr)) |
420a0d19 CE |
2146 | { |
2147 | if (state->verify_requirement != VERIFY_OPTIONAL) | |
2148 | { | |
2ea97746 | 2149 | (void) tls_error(US"certificate verification failed", *errstr, NULL, errstr); |
420a0d19 CE |
2150 | return FAIL; |
2151 | } | |
2152 | DEBUG(D_tls) | |
2153 | debug_printf("TLS: continuing on only because verification was optional, after: %s\n", | |
2ea97746 | 2154 | *errstr); |
420a0d19 CE |
2155 | } |
2156 | ||
2157 | /* Figure out peer DN, and if authenticated, etc. */ | |
2158 | ||
2ea97746 | 2159 | if ((rc = peer_status(state, NULL)) != OK) return rc; |
420a0d19 CE |
2160 | |
2161 | /* Sets various Exim expansion variables; always safe within server */ | |
2162 | ||
2163 | extract_exim_vars_from_tls_state(state); | |
2164 | ||
2165 | /* TLS has been set up. Adjust the input functions to read via TLS, | |
2166 | and initialize appropriately. */ | |
2167 | ||
2168 | state->xfer_buffer = store_malloc(ssl_xfer_buffer_size); | |
2169 | ||
2170 | receive_getc = tls_getc; | |
2ea97746 CE |
2171 | receive_getbuf = tls_getbuf; |
2172 | receive_get_cache = tls_get_cache; | |
420a0d19 CE |
2173 | receive_ungetc = tls_ungetc; |
2174 | receive_feof = tls_feof; | |
2175 | receive_ferror = tls_ferror; | |
2176 | receive_smtp_buffered = tls_smtp_buffered; | |
2177 | ||
2178 | return OK; | |
2179 | } | |
2180 | ||
2181 | ||
2182 | ||
2183 | ||
2ea97746 CE |
2184 | static void |
2185 | tls_client_setup_hostname_checks(host_item * host, exim_gnutls_state_st * state, | |
2186 | smtp_transport_options_block * ob) | |
2187 | { | |
2188 | if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK) | |
2189 | { | |
2190 | state->exp_tls_verify_cert_hostnames = | |
2191 | #ifdef SUPPORT_I18N | |
2192 | string_domain_utf8_to_alabel(host->name, NULL); | |
2193 | #else | |
2194 | host->name; | |
2195 | #endif | |
2196 | DEBUG(D_tls) | |
2197 | debug_printf("TLS: server cert verification includes hostname: \"%s\".\n", | |
2198 | state->exp_tls_verify_cert_hostnames); | |
2199 | } | |
2200 | } | |
2201 | ||
2202 | ||
2203 | ||
2204 | ||
2205 | #ifdef SUPPORT_DANE | |
2206 | /* Given our list of RRs from the TLSA lookup, build a lookup block in | |
2207 | GnuTLS-DANE's preferred format. Hang it on the state str for later | |
2208 | use in DANE verification. | |
2209 | ||
2210 | We point at the dnsa data not copy it, so it must remain valid until | |
2211 | after verification is done.*/ | |
2212 | ||
2213 | static BOOL | |
2214 | dane_tlsa_load(exim_gnutls_state_st * state, dns_answer * dnsa) | |
2215 | { | |
2216 | dns_record * rr; | |
2217 | dns_scan dnss; | |
2218 | int i; | |
2219 | const char ** dane_data; | |
2220 | int * dane_data_len; | |
2221 | ||
2222 | for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS), i = 1; | |
2223 | rr; | |
2224 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT) | |
2225 | ) if (rr->type == T_TLSA) i++; | |
2226 | ||
2227 | dane_data = store_get(i * sizeof(uschar *)); | |
2228 | dane_data_len = store_get(i * sizeof(int)); | |
2229 | ||
2230 | for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS), i = 0; | |
2231 | rr; | |
2232 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT) | |
2233 | ) if (rr->type == T_TLSA && rr->size > 3) | |
2234 | { | |
2235 | const uschar * p = rr->data; | |
2236 | uint8_t usage = p[0], sel = p[1], type = p[2]; | |
2237 | ||
2238 | DEBUG(D_tls) | |
2239 | debug_printf("TLSA: %d %d %d size %d\n", usage, sel, type, rr->size); | |
2240 | ||
2241 | if ( (usage != DANESSL_USAGE_DANE_TA && usage != DANESSL_USAGE_DANE_EE) | |
2242 | || (sel != 0 && sel != 1) | |
2243 | ) | |
2244 | continue; | |
2245 | switch(type) | |
2246 | { | |
2247 | case 0: /* Full: cannot check at present */ | |
2248 | break; | |
2249 | case 1: if (rr->size != 3 + 256/8) continue; /* sha2-256 */ | |
2250 | break; | |
2251 | case 2: if (rr->size != 3 + 512/8) continue; /* sha2-512 */ | |
2252 | break; | |
2253 | default: continue; | |
2254 | } | |
2255 | ||
2256 | tls_out.tlsa_usage |= 1<<usage; | |
2257 | dane_data[i] = CS p; | |
2258 | dane_data_len[i++] = rr->size; | |
2259 | } | |
2260 | ||
2261 | if (!i) return FALSE; | |
2262 | ||
2263 | dane_data[i] = NULL; | |
2264 | dane_data_len[i] = 0; | |
2265 | ||
2266 | state->dane_data = (char * const *)dane_data; | |
2267 | state->dane_data_len = dane_data_len; | |
2268 | return TRUE; | |
2269 | } | |
2270 | #endif | |
2271 | ||
2272 | ||
2273 | ||
420a0d19 CE |
2274 | /************************************************* |
2275 | * Start a TLS session in a client * | |
2276 | *************************************************/ | |
2277 | ||
2278 | /* Called from the smtp transport after STARTTLS has been accepted. | |
2279 | ||
2280 | Arguments: | |
2281 | fd the fd of the connection | |
2ea97746 | 2282 | host connected host (for messages and option-tests) |
420a0d19 | 2283 | addr the first address (not used) |
2ea97746 CE |
2284 | tb transport (always smtp) |
2285 | tlsa_dnsa non-NULL, either request or require dane for this host, and | |
2286 | a TLSA record found. Therefore, dane verify required. | |
2287 | Which implies cert must be requested and supplied, dane | |
2288 | verify must pass, and cert verify irrelevant (incl. | |
2289 | hostnames), and (caller handled) require_tls | |
2290 | tlsp record details of channel configuration | |
2291 | errstr error string pointer | |
2292 | ||
2293 | Returns: Pointer to TLS session context, or NULL on error | |
420a0d19 CE |
2294 | */ |
2295 | ||
2ea97746 | 2296 | void * |
420a0d19 CE |
2297 | tls_client_start(int fd, host_item *host, |
2298 | address_item *addr ARG_UNUSED, | |
2ea97746 CE |
2299 | transport_instance * tb, |
2300 | #ifdef SUPPORT_DANE | |
2301 | dns_answer * tlsa_dnsa, | |
2302 | #endif | |
2303 | tls_support * tlsp, uschar ** errstr) | |
420a0d19 | 2304 | { |
2ea97746 CE |
2305 | smtp_transport_options_block *ob = tb |
2306 | ? (smtp_transport_options_block *)tb->options_block | |
2307 | : &smtp_transport_option_defaults; | |
420a0d19 | 2308 | int rc; |
2ea97746 CE |
2309 | exim_gnutls_state_st * state = NULL; |
2310 | uschar *cipher_list = NULL; | |
2311 | ||
420a0d19 | 2312 | #ifndef DISABLE_OCSP |
2ea97746 CE |
2313 | BOOL require_ocsp = |
2314 | verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK; | |
420a0d19 | 2315 | BOOL request_ocsp = require_ocsp ? TRUE |
2ea97746 | 2316 | : verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK; |
420a0d19 CE |
2317 | #endif |
2318 | ||
2319 | DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", fd); | |
2320 | ||
2ea97746 CE |
2321 | #ifdef SUPPORT_DANE |
2322 | if (tlsa_dnsa && ob->dane_require_tls_ciphers) | |
2323 | { | |
2324 | /* not using expand_check_tlsvar because not yet in state */ | |
2325 | if (!expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers", | |
2326 | &cipher_list, errstr)) | |
2327 | return NULL; | |
2328 | cipher_list = cipher_list && *cipher_list | |
2329 | ? ob->dane_require_tls_ciphers : ob->tls_require_ciphers; | |
2330 | } | |
2331 | #endif | |
2332 | ||
2333 | if (!cipher_list) | |
2334 | cipher_list = ob->tls_require_ciphers; | |
2335 | ||
2336 | if (tls_init(host, ob->tls_certificate, ob->tls_privatekey, | |
420a0d19 | 2337 | ob->tls_sni, ob->tls_verify_certificates, ob->tls_crl, |
2ea97746 CE |
2338 | cipher_list, &state, tlsp, errstr) != OK) |
2339 | return NULL; | |
420a0d19 CE |
2340 | |
2341 | { | |
2342 | int dh_min_bits = ob->tls_dh_min_bits; | |
2343 | if (dh_min_bits < EXIM_CLIENT_DH_MIN_MIN_BITS) | |
2344 | { | |
2345 | DEBUG(D_tls) | |
2346 | debug_printf("WARNING: tls_dh_min_bits far too low," | |
2347 | " clamping %d up to %d\n", | |
2348 | dh_min_bits, EXIM_CLIENT_DH_MIN_MIN_BITS); | |
2349 | dh_min_bits = EXIM_CLIENT_DH_MIN_MIN_BITS; | |
2350 | } | |
2351 | ||
2352 | DEBUG(D_tls) debug_printf("Setting D-H prime minimum" | |
2353 | " acceptable bits to %d\n", | |
2354 | dh_min_bits); | |
2355 | gnutls_dh_set_prime_bits(state->session, dh_min_bits); | |
2356 | } | |
2357 | ||
2ea97746 | 2358 | /* Stick to the old behaviour for compatibility if tls_verify_certificates is |
420a0d19 CE |
2359 | set but both tls_verify_hosts and tls_try_verify_hosts are unset. Check only |
2360 | the specified host patterns if one of them is defined */ | |
2361 | ||
2ea97746 CE |
2362 | #ifdef SUPPORT_DANE |
2363 | if (tlsa_dnsa && dane_tlsa_load(state, tlsa_dnsa)) | |
420a0d19 | 2364 | { |
2ea97746 CE |
2365 | DEBUG(D_tls) |
2366 | debug_printf("TLS: server certificate DANE required.\n"); | |
2367 | state->verify_requirement = VERIFY_DANE; | |
2368 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE); | |
2369 | } | |
2370 | else | |
420a0d19 | 2371 | #endif |
2ea97746 CE |
2372 | if ( ( state->exp_tls_verify_certificates |
2373 | && !ob->tls_verify_hosts | |
2374 | && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts) | |
2375 | ) | |
2376 | || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK | |
2377 | ) | |
2378 | { | |
2379 | tls_client_setup_hostname_checks(host, state, ob); | |
2380 | DEBUG(D_tls) | |
2381 | debug_printf("TLS: server certificate verification required.\n"); | |
2382 | state->verify_requirement = VERIFY_REQUIRED; | |
420a0d19 CE |
2383 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE); |
2384 | } | |
2ea97746 | 2385 | else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK) |
420a0d19 | 2386 | { |
2ea97746 | 2387 | tls_client_setup_hostname_checks(host, state, ob); |
420a0d19 CE |
2388 | DEBUG(D_tls) |
2389 | debug_printf("TLS: server certificate verification optional.\n"); | |
2390 | state->verify_requirement = VERIFY_OPTIONAL; | |
2391 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST); | |
2392 | } | |
2393 | else | |
2394 | { | |
2395 | DEBUG(D_tls) | |
2396 | debug_printf("TLS: server certificate verification not required.\n"); | |
2397 | state->verify_requirement = VERIFY_NONE; | |
2398 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE); | |
2399 | } | |
2400 | ||
2401 | #ifndef DISABLE_OCSP | |
2402 | /* supported since GnuTLS 3.1.3 */ | |
2403 | if (request_ocsp) | |
2404 | { | |
2405 | DEBUG(D_tls) debug_printf("TLS: will request OCSP stapling\n"); | |
2406 | if ((rc = gnutls_ocsp_status_request_enable_client(state->session, | |
2407 | NULL, 0, NULL)) != OK) | |
2ea97746 CE |
2408 | { |
2409 | tls_error(US"cert-status-req", US gnutls_strerror(rc), state->host, errstr); | |
2410 | return NULL; | |
2411 | } | |
2412 | tlsp->ocsp = OCSP_NOT_RESP; | |
2413 | } | |
2414 | #endif | |
2415 | ||
2416 | #ifndef DISABLE_EVENT | |
2417 | if (tb && tb->event_action) | |
2418 | { | |
2419 | state->event_action = tb->event_action; | |
2420 | gnutls_session_set_ptr(state->session, state); | |
2421 | gnutls_certificate_set_verify_function(state->x509_cred, verify_cb); | |
420a0d19 CE |
2422 | } |
2423 | #endif | |
2424 | ||
2ea97746 | 2425 | gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr_t)(long) fd); |
420a0d19 CE |
2426 | state->fd_in = fd; |
2427 | state->fd_out = fd; | |
2428 | ||
2429 | DEBUG(D_tls) debug_printf("about to gnutls_handshake\n"); | |
2430 | /* There doesn't seem to be a built-in timeout on connection. */ | |
2431 | ||
2432 | sigalrm_seen = FALSE; | |
2ea97746 | 2433 | ALARM(ob->command_timeout); |
420a0d19 | 2434 | do |
420a0d19 | 2435 | rc = gnutls_handshake(state->session); |
2ea97746 CE |
2436 | while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen); |
2437 | ALARM_CLR(0); | |
420a0d19 CE |
2438 | |
2439 | if (rc != GNUTLS_E_SUCCESS) | |
2ea97746 CE |
2440 | { |
2441 | if (sigalrm_seen) | |
2442 | { | |
2443 | gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_USER_CANCELED); | |
2444 | tls_error(US"gnutls_handshake", US"timed out", state->host, errstr); | |
2445 | } | |
2446 | else | |
2447 | tls_error(US"gnutls_handshake", US gnutls_strerror(rc), state->host, errstr); | |
2448 | return NULL; | |
2449 | } | |
420a0d19 CE |
2450 | |
2451 | DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n"); | |
2452 | ||
2453 | /* Verify late */ | |
2454 | ||
2ea97746 CE |
2455 | if (!verify_certificate(state, errstr)) |
2456 | { | |
2457 | tls_error(US"certificate verification failed", *errstr, state->host, errstr); | |
2458 | return NULL; | |
2459 | } | |
420a0d19 CE |
2460 | |
2461 | #ifndef DISABLE_OCSP | |
2462 | if (require_ocsp) | |
2463 | { | |
2464 | DEBUG(D_tls) | |
2465 | { | |
2466 | gnutls_datum_t stapling; | |
2467 | gnutls_ocsp_resp_t resp; | |
2468 | gnutls_datum_t printed; | |
2469 | if ( (rc= gnutls_ocsp_status_request_get(state->session, &stapling)) == 0 | |
2470 | && (rc= gnutls_ocsp_resp_init(&resp)) == 0 | |
2471 | && (rc= gnutls_ocsp_resp_import(resp, &stapling)) == 0 | |
2472 | && (rc= gnutls_ocsp_resp_print(resp, GNUTLS_OCSP_PRINT_FULL, &printed)) == 0 | |
2473 | ) | |
2474 | { | |
2475 | debug_printf("%.4096s", printed.data); | |
2476 | gnutls_free(printed.data); | |
2477 | } | |
2478 | else | |
2ea97746 | 2479 | (void) tls_error(US"ocsp decode", US gnutls_strerror(rc), state->host, errstr); |
420a0d19 CE |
2480 | } |
2481 | ||
2482 | if (gnutls_ocsp_status_request_is_checked(state->session, 0) == 0) | |
2483 | { | |
2ea97746 CE |
2484 | tlsp->ocsp = OCSP_FAILED; |
2485 | tls_error(US"certificate status check failed", NULL, state->host, errstr); | |
2486 | return NULL; | |
420a0d19 CE |
2487 | } |
2488 | DEBUG(D_tls) debug_printf("Passed OCSP checking\n"); | |
2ea97746 | 2489 | tlsp->ocsp = OCSP_VFIED; |
420a0d19 CE |
2490 | } |
2491 | #endif | |
2492 | ||
2493 | /* Figure out peer DN, and if authenticated, etc. */ | |
2494 | ||
2ea97746 CE |
2495 | if (peer_status(state, errstr) != OK) |
2496 | return NULL; | |
420a0d19 CE |
2497 | |
2498 | /* Sets various Exim expansion variables; may need to adjust for ACL callouts */ | |
2499 | ||
2500 | extract_exim_vars_from_tls_state(state); | |
2501 | ||
2ea97746 | 2502 | return state; |
420a0d19 CE |
2503 | } |
2504 | ||
2505 | ||
2506 | ||
2507 | ||
2508 | /************************************************* | |
2509 | * Close down a TLS session * | |
2510 | *************************************************/ | |
2511 | ||
2512 | /* This is also called from within a delivery subprocess forked from the | |
2513 | daemon, to shut down the TLS library, without actually doing a shutdown (which | |
2514 | would tamper with the TLS session in the parent process). | |
2515 | ||
2ea97746 CE |
2516 | Arguments: |
2517 | ct_ctx client context pointer, or NULL for the one global server context | |
2518 | shutdown 1 if TLS close-alert is to be sent, | |
2519 | 2 if also response to be waited for | |
2520 | ||
420a0d19 CE |
2521 | Returns: nothing |
2522 | */ | |
2523 | ||
2524 | void | |
2ea97746 | 2525 | tls_close(void * ct_ctx, int shutdown) |
420a0d19 | 2526 | { |
2ea97746 | 2527 | exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server; |
420a0d19 | 2528 | |
2ea97746 | 2529 | if (!state->tlsp || state->tlsp->active.sock < 0) return; /* TLS was not active */ |
420a0d19 CE |
2530 | |
2531 | if (shutdown) | |
2532 | { | |
2ea97746 CE |
2533 | DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n", |
2534 | shutdown > 1 ? " (with response-wait)" : ""); | |
2535 | ||
2536 | ALARM(2); | |
2537 | gnutls_bye(state->session, shutdown > 1 ? GNUTLS_SHUT_RDWR : GNUTLS_SHUT_WR); | |
2538 | ALARM_CLR(0); | |
420a0d19 CE |
2539 | } |
2540 | ||
2541 | gnutls_deinit(state->session); | |
2ea97746 CE |
2542 | gnutls_certificate_free_credentials(state->x509_cred); |
2543 | ||
420a0d19 | 2544 | |
2ea97746 CE |
2545 | state->tlsp->active.sock = -1; |
2546 | state->tlsp->active.tls_ctx = NULL; | |
2547 | if (state->xfer_buffer) store_free(state->xfer_buffer); | |
420a0d19 | 2548 | memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); |
2ea97746 CE |
2549 | } |
2550 | ||
2551 | ||
2552 | ||
2553 | ||
2554 | static BOOL | |
2555 | tls_refill(unsigned lim) | |
2556 | { | |
2557 | exim_gnutls_state_st * state = &state_server; | |
2558 | ssize_t inbytes; | |
2559 | ||
2560 | DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%p, %p, %u)\n", | |
2561 | state->session, state->xfer_buffer, ssl_xfer_buffer_size); | |
2562 | ||
2563 | sigalrm_seen = FALSE; | |
2564 | if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout); | |
420a0d19 | 2565 | |
2ea97746 CE |
2566 | do |
2567 | inbytes = gnutls_record_recv(state->session, state->xfer_buffer, | |
2568 | MIN(ssl_xfer_buffer_size, lim)); | |
2569 | while (inbytes == GNUTLS_E_AGAIN); | |
2570 | ||
2571 | if (smtp_receive_timeout > 0) ALARM_CLR(0); | |
2572 | ||
2573 | if (had_command_timeout) /* set by signal handler */ | |
2574 | smtp_command_timeout_exit(); /* does not return */ | |
2575 | if (had_command_sigterm) | |
2576 | smtp_command_sigterm_exit(); | |
2577 | if (had_data_timeout) | |
2578 | smtp_data_timeout_exit(); | |
2579 | if (had_data_sigint) | |
2580 | smtp_data_sigint_exit(); | |
2581 | ||
2582 | /* Timeouts do not get this far. A zero-byte return appears to mean that the | |
2583 | TLS session has been closed down, not that the socket itself has been closed | |
2584 | down. Revert to non-TLS handling. */ | |
2585 | ||
2586 | if (sigalrm_seen) | |
420a0d19 | 2587 | { |
2ea97746 CE |
2588 | DEBUG(D_tls) debug_printf("Got tls read timeout\n"); |
2589 | state->xfer_error = TRUE; | |
2590 | return FALSE; | |
420a0d19 CE |
2591 | } |
2592 | ||
2ea97746 CE |
2593 | else if (inbytes == 0) |
2594 | { | |
2595 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); | |
2596 | ||
2597 | receive_getc = smtp_getc; | |
2598 | receive_getbuf = smtp_getbuf; | |
2599 | receive_get_cache = smtp_get_cache; | |
2600 | receive_ungetc = smtp_ungetc; | |
2601 | receive_feof = smtp_feof; | |
2602 | receive_ferror = smtp_ferror; | |
2603 | receive_smtp_buffered = smtp_buffered; | |
2604 | ||
2605 | gnutls_deinit(state->session); | |
2606 | gnutls_certificate_free_credentials(state->x509_cred); | |
420a0d19 | 2607 | |
2ea97746 CE |
2608 | state->session = NULL; |
2609 | state->tlsp->active.sock = -1; | |
2610 | state->tlsp->active.tls_ctx = NULL; | |
2611 | state->tlsp->bits = 0; | |
2612 | state->tlsp->certificate_verified = FALSE; | |
2613 | tls_channelbinding_b64 = NULL; | |
2614 | state->tlsp->cipher = NULL; | |
2615 | state->tlsp->peercert = NULL; | |
2616 | state->tlsp->peerdn = NULL; | |
420a0d19 | 2617 | |
2ea97746 CE |
2618 | return FALSE; |
2619 | } | |
2620 | ||
2621 | /* Handle genuine errors */ | |
420a0d19 | 2622 | |
2ea97746 CE |
2623 | else if (inbytes < 0) |
2624 | { | |
2625 | DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv(\n", __FUNCTION__); | |
2626 | record_io_error(state, (int) inbytes, US"recv", NULL); | |
2627 | state->xfer_error = TRUE; | |
2628 | return FALSE; | |
2629 | } | |
2630 | #ifndef DISABLE_DKIM | |
2631 | dkim_exim_verify_feed(state->xfer_buffer, inbytes); | |
2632 | #endif | |
2633 | state->xfer_buffer_hwm = (int) inbytes; | |
2634 | state->xfer_buffer_lwm = 0; | |
2635 | return TRUE; | |
2636 | } | |
420a0d19 CE |
2637 | |
2638 | /************************************************* | |
2639 | * TLS version of getc * | |
2640 | *************************************************/ | |
2641 | ||
2642 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, | |
2643 | it refills the buffer via the GnuTLS reading function. | |
2644 | Only used by the server-side TLS. | |
2645 | ||
2646 | This feeds DKIM and should be used for all message-body reads. | |
2647 | ||
2ea97746 | 2648 | Arguments: lim Maximum amount to read/buffer |
420a0d19 CE |
2649 | Returns: the next character or EOF |
2650 | */ | |
2651 | ||
2652 | int | |
2ea97746 | 2653 | tls_getc(unsigned lim) |
420a0d19 | 2654 | { |
2ea97746 CE |
2655 | exim_gnutls_state_st * state = &state_server; |
2656 | ||
420a0d19 | 2657 | if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm) |
2ea97746 CE |
2658 | if (!tls_refill(lim)) |
2659 | return state->xfer_error ? EOF : smtp_getc(lim); | |
420a0d19 | 2660 | |
2ea97746 | 2661 | /* Something in the buffer; return next uschar */ |
420a0d19 | 2662 | |
2ea97746 CE |
2663 | return state->xfer_buffer[state->xfer_buffer_lwm++]; |
2664 | } | |
420a0d19 | 2665 | |
2ea97746 CE |
2666 | uschar * |
2667 | tls_getbuf(unsigned * len) | |
2668 | { | |
2669 | exim_gnutls_state_st * state = &state_server; | |
2670 | unsigned size; | |
2671 | uschar * buf; | |
420a0d19 | 2672 | |
2ea97746 CE |
2673 | if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm) |
2674 | if (!tls_refill(*len)) | |
420a0d19 | 2675 | { |
2ea97746 CE |
2676 | if (!state->xfer_error) return smtp_getbuf(len); |
2677 | *len = 0; | |
2678 | return NULL; | |
420a0d19 CE |
2679 | } |
2680 | ||
2ea97746 CE |
2681 | if ((size = state->xfer_buffer_hwm - state->xfer_buffer_lwm) > *len) |
2682 | size = *len; | |
2683 | buf = &state->xfer_buffer[state->xfer_buffer_lwm]; | |
2684 | state->xfer_buffer_lwm += size; | |
2685 | *len = size; | |
2686 | return buf; | |
2687 | } | |
420a0d19 | 2688 | |
2ea97746 CE |
2689 | |
2690 | void | |
2691 | tls_get_cache() | |
2692 | { | |
420a0d19 | 2693 | #ifndef DISABLE_DKIM |
2ea97746 CE |
2694 | exim_gnutls_state_st * state = &state_server; |
2695 | int n = state->xfer_buffer_hwm - state->xfer_buffer_lwm; | |
2696 | if (n > 0) | |
2697 | dkim_exim_verify_feed(state->xfer_buffer+state->xfer_buffer_lwm, n); | |
420a0d19 | 2698 | #endif |
2ea97746 | 2699 | } |
420a0d19 | 2700 | |
420a0d19 | 2701 | |
2ea97746 CE |
2702 | BOOL |
2703 | tls_could_read(void) | |
2704 | { | |
2705 | return state_server.xfer_buffer_lwm < state_server.xfer_buffer_hwm | |
2706 | || gnutls_record_check_pending(state_server.session) > 0; | |
420a0d19 CE |
2707 | } |
2708 | ||
2709 | ||
2710 | ||
2711 | ||
2712 | /************************************************* | |
2713 | * Read bytes from TLS channel * | |
2714 | *************************************************/ | |
2715 | ||
2716 | /* This does not feed DKIM, so if the caller uses this for reading message body, | |
2717 | then the caller must feed DKIM. | |
2718 | ||
2719 | Arguments: | |
2ea97746 | 2720 | ct_ctx client context pointer, or NULL for the one global server context |
420a0d19 CE |
2721 | buff buffer of data |
2722 | len size of buffer | |
2723 | ||
2724 | Returns: the number of bytes read | |
2ea97746 | 2725 | -1 after a failed read, including EOF |
420a0d19 CE |
2726 | */ |
2727 | ||
2728 | int | |
2ea97746 | 2729 | tls_read(void * ct_ctx, uschar *buff, size_t len) |
420a0d19 | 2730 | { |
2ea97746 | 2731 | exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server; |
420a0d19 CE |
2732 | ssize_t inbytes; |
2733 | ||
2734 | if (len > INT_MAX) | |
2735 | len = INT_MAX; | |
2736 | ||
2737 | if (state->xfer_buffer_lwm < state->xfer_buffer_hwm) | |
2738 | DEBUG(D_tls) | |
2739 | debug_printf("*** PROBABLY A BUG *** " \ | |
2740 | "tls_read() called with data in the tls_getc() buffer, %d ignored\n", | |
2741 | state->xfer_buffer_hwm - state->xfer_buffer_lwm); | |
2742 | ||
2743 | DEBUG(D_tls) | |
2744 | debug_printf("Calling gnutls_record_recv(%p, %p, " SIZE_T_FMT ")\n", | |
2745 | state->session, buff, len); | |
2746 | ||
2ea97746 CE |
2747 | do |
2748 | inbytes = gnutls_record_recv(state->session, buff, len); | |
2749 | while (inbytes == GNUTLS_E_AGAIN); | |
2750 | ||
420a0d19 CE |
2751 | if (inbytes > 0) return inbytes; |
2752 | if (inbytes == 0) | |
2753 | { | |
2754 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); | |
2755 | } | |
2ea97746 CE |
2756 | else |
2757 | { | |
2758 | DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv(\n", __FUNCTION__); | |
2759 | record_io_error(state, (int)inbytes, US"recv", NULL); | |
2760 | } | |
420a0d19 CE |
2761 | |
2762 | return -1; | |
2763 | } | |
2764 | ||
2765 | ||
2766 | ||
2767 | ||
2768 | /************************************************* | |
2769 | * Write bytes down TLS channel * | |
2770 | *************************************************/ | |
2771 | ||
2772 | /* | |
2773 | Arguments: | |
2ea97746 | 2774 | ct_ctx client context pointer, or NULL for the one global server context |
420a0d19 CE |
2775 | buff buffer of data |
2776 | len number of bytes | |
2ea97746 | 2777 | more more data expected soon |
420a0d19 CE |
2778 | |
2779 | Returns: the number of bytes after a successful write, | |
2780 | -1 after a failed write | |
2781 | */ | |
2782 | ||
2783 | int | |
2ea97746 | 2784 | tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more) |
420a0d19 CE |
2785 | { |
2786 | ssize_t outbytes; | |
2787 | size_t left = len; | |
2ea97746 CE |
2788 | exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server; |
2789 | #ifdef SUPPORT_CORK | |
2790 | static BOOL corked = FALSE; | |
2791 | ||
2792 | if (more && !corked) gnutls_record_cork(state->session); | |
2793 | #endif | |
2794 | ||
2795 | DEBUG(D_tls) debug_printf("%s(%p, " SIZE_T_FMT "%s)\n", __FUNCTION__, | |
2796 | buff, left, more ? ", more" : ""); | |
420a0d19 | 2797 | |
420a0d19 CE |
2798 | while (left > 0) |
2799 | { | |
2800 | DEBUG(D_tls) debug_printf("gnutls_record_send(SSL, %p, " SIZE_T_FMT ")\n", | |
2801 | buff, left); | |
2ea97746 CE |
2802 | |
2803 | do | |
2804 | outbytes = gnutls_record_send(state->session, buff, left); | |
2805 | while (outbytes == GNUTLS_E_AGAIN); | |
420a0d19 CE |
2806 | |
2807 | DEBUG(D_tls) debug_printf("outbytes=" SSIZE_T_FMT "\n", outbytes); | |
2808 | if (outbytes < 0) | |
2809 | { | |
2ea97746 | 2810 | DEBUG(D_tls) debug_printf("%s: gnutls_record_send err\n", __FUNCTION__); |
420a0d19 CE |
2811 | record_io_error(state, outbytes, US"send", NULL); |
2812 | return -1; | |
2813 | } | |
2814 | if (outbytes == 0) | |
2815 | { | |
2816 | record_io_error(state, 0, US"send", US"TLS channel closed on write"); | |
2817 | return -1; | |
2818 | } | |
2819 | ||
2820 | left -= outbytes; | |
2821 | buff += outbytes; | |
2822 | } | |
2823 | ||
2824 | if (len > INT_MAX) | |
2825 | { | |
2826 | DEBUG(D_tls) | |
2827 | debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT ") than INT_MAX\n", | |
2828 | len); | |
2829 | len = INT_MAX; | |
2830 | } | |
2831 | ||
2ea97746 CE |
2832 | #ifdef SUPPORT_CORK |
2833 | if (more != corked) | |
2834 | { | |
2835 | if (!more) (void) gnutls_record_uncork(state->session, 0); | |
2836 | corked = more; | |
2837 | } | |
2838 | #endif | |
2839 | ||
420a0d19 CE |
2840 | return (int) len; |
2841 | } | |
2842 | ||
2843 | ||
2844 | ||
2845 | ||
2846 | /************************************************* | |
2847 | * Random number generation * | |
2848 | *************************************************/ | |
2849 | ||
2850 | /* Pseudo-random number generation. The result is not expected to be | |
2851 | cryptographically strong but not so weak that someone will shoot themselves | |
2852 | in the foot using it as a nonce in input in some email header scheme or | |
2853 | whatever weirdness they'll twist this into. The result should handle fork() | |
2854 | and avoid repeating sequences. OpenSSL handles that for us. | |
2855 | ||
2856 | Arguments: | |
2857 | max range maximum | |
2858 | Returns a random number in range [0, max-1] | |
2859 | */ | |
2860 | ||
2861 | #ifdef HAVE_GNUTLS_RND | |
2862 | int | |
2863 | vaguely_random_number(int max) | |
2864 | { | |
2865 | unsigned int r; | |
2866 | int i, needed_len; | |
2867 | uschar *p; | |
2868 | uschar smallbuf[sizeof(r)]; | |
2869 | ||
2870 | if (max <= 1) | |
2871 | return 0; | |
2872 | ||
2873 | needed_len = sizeof(r); | |
2874 | /* Don't take 8 times more entropy than needed if int is 8 octets and we were | |
2875 | * asked for a number less than 10. */ | |
2876 | for (r = max, i = 0; r; ++i) | |
2877 | r >>= 1; | |
2878 | i = (i + 7) / 8; | |
2879 | if (i < needed_len) | |
2880 | needed_len = i; | |
2881 | ||
2882 | i = gnutls_rnd(GNUTLS_RND_NONCE, smallbuf, needed_len); | |
2883 | if (i < 0) | |
2884 | { | |
2885 | DEBUG(D_all) debug_printf("gnutls_rnd() failed, using fallback.\n"); | |
2886 | return vaguely_random_number_fallback(max); | |
2887 | } | |
2888 | r = 0; | |
2889 | for (p = smallbuf; needed_len; --needed_len, ++p) | |
2890 | { | |
2891 | r *= 256; | |
2892 | r += *p; | |
2893 | } | |
2894 | ||
2895 | /* We don't particularly care about weighted results; if someone wants | |
2896 | * smooth distribution and cares enough then they should submit a patch then. */ | |
2897 | return r % max; | |
2898 | } | |
2899 | #else /* HAVE_GNUTLS_RND */ | |
2900 | int | |
2901 | vaguely_random_number(int max) | |
2902 | { | |
2903 | return vaguely_random_number_fallback(max); | |
2904 | } | |
2905 | #endif /* HAVE_GNUTLS_RND */ | |
2906 | ||
2907 | ||
2908 | ||
2909 | ||
2910 | /************************************************* | |
2911 | * Let tls_require_ciphers be checked at startup * | |
2912 | *************************************************/ | |
2913 | ||
2914 | /* The tls_require_ciphers option, if set, must be something which the | |
2915 | library can parse. | |
2916 | ||
2917 | Returns: NULL on success, or error message | |
2918 | */ | |
2919 | ||
2920 | uschar * | |
2921 | tls_validate_require_cipher(void) | |
2922 | { | |
2923 | int rc; | |
2924 | uschar *expciphers = NULL; | |
2925 | gnutls_priority_t priority_cache; | |
2926 | const char *errpos; | |
2ea97746 | 2927 | uschar * dummy_errstr; |
420a0d19 CE |
2928 | |
2929 | #define validate_check_rc(Label) do { \ | |
2930 | if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \ | |
2931 | return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0) | |
2932 | #define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0) | |
2933 | ||
2934 | if (exim_gnutls_base_init_done) | |
2935 | log_write(0, LOG_MAIN|LOG_PANIC, | |
2936 | "already initialised GnuTLS, Exim developer bug"); | |
2937 | ||
2938 | #ifdef HAVE_GNUTLS_PKCS11 | |
2939 | if (!gnutls_allow_auto_pkcs11) | |
2940 | { | |
2941 | rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL); | |
2942 | validate_check_rc(US"gnutls_pkcs11_init"); | |
2943 | } | |
2944 | #endif | |
2945 | rc = gnutls_global_init(); | |
2946 | validate_check_rc(US"gnutls_global_init()"); | |
2947 | exim_gnutls_base_init_done = TRUE; | |
2948 | ||
2949 | if (!(tls_require_ciphers && *tls_require_ciphers)) | |
2950 | return_deinit(NULL); | |
2951 | ||
2ea97746 CE |
2952 | if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers, |
2953 | &dummy_errstr)) | |
420a0d19 CE |
2954 | return_deinit(US"failed to expand tls_require_ciphers"); |
2955 | ||
2956 | if (!(expciphers && *expciphers)) | |
2957 | return_deinit(NULL); | |
2958 | ||
2959 | DEBUG(D_tls) | |
2960 | debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers); | |
2961 | ||
2962 | rc = gnutls_priority_init(&priority_cache, CS expciphers, &errpos); | |
2963 | validate_check_rc(string_sprintf( | |
2964 | "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"", | |
2965 | expciphers, errpos - CS expciphers, errpos)); | |
2966 | ||
2967 | #undef return_deinit | |
2968 | #undef validate_check_rc | |
2969 | gnutls_global_deinit(); | |
2970 | ||
2971 | return NULL; | |
2972 | } | |
2973 | ||
2974 | ||
2975 | ||
2976 | ||
2977 | /************************************************* | |
2978 | * Report the library versions. * | |
2979 | *************************************************/ | |
2980 | ||
2981 | /* See a description in tls-openssl.c for an explanation of why this exists. | |
2982 | ||
2983 | Arguments: a FILE* to print the results to | |
2984 | Returns: nothing | |
2985 | */ | |
2986 | ||
2987 | void | |
2988 | tls_version_report(FILE *f) | |
2989 | { | |
2990 | fprintf(f, "Library version: GnuTLS: Compile: %s\n" | |
2991 | " Runtime: %s\n", | |
2992 | LIBGNUTLS_VERSION, | |
2993 | gnutls_check_version(NULL)); | |
2994 | } | |
2995 | ||
2996 | /* vi: aw ai sw=2 | |
2997 | */ | |
2998 | /* End of tls-gnu.c */ |