Commit | Line | Data |
---|---|---|
059ec3d9 PH |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | ||
17c76198 | 5 | /* Copyright (c) University of Cambridge 1995 - 2012 */ |
059ec3d9 PH |
6 | /* See the file NOTICE for conditions of use and distribution. */ |
7 | ||
17c76198 | 8 | /* Copyright (c) Phil Pennock 2012 */ |
059ec3d9 | 9 | |
17c76198 PP |
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. | |
059ec3d9 | 13 | |
17c76198 PP |
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 | |
16 | Mavroyanopoulos. The revamp is partially a rewrite, partially cut&paste as | |
17 | appropriate. | |
059ec3d9 | 18 | |
17c76198 PP |
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). | |
059ec3d9 | 23 | |
17c76198 PP |
24 | Keeping client and server variables more split than before and is currently |
25 | the norm, in anticipation of TLS in ACL callouts. | |
059ec3d9 | 26 | |
17c76198 PP |
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. | |
059ec3d9 | 31 | |
17c76198 PP |
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 | */ | |
b5aea5e1 | 36 | |
17c76198 PP |
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> | |
059ec3d9 | 42 | |
17c76198 | 43 | /* GnuTLS 2 vs 3 |
059ec3d9 | 44 | |
17c76198 PP |
45 | GnuTLS 3 only: |
46 | gnutls_global_set_audit_log_function() | |
059ec3d9 | 47 | |
17c76198 PP |
48 | Changes: |
49 | gnutls_certificate_verify_peers2(): is new, drop the 2 for old version | |
50 | */ | |
059ec3d9 | 51 | |
17c76198 | 52 | /* Local static variables for GnuTLS */ |
059ec3d9 | 53 | |
17c76198 | 54 | /* Values for verify_requirement */ |
059ec3d9 | 55 | |
17c76198 | 56 | enum peer_verify_requirement { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED }; |
059ec3d9 | 57 | |
17c76198 PP |
58 | /* This holds most state for server or client; with this, we can set up an |
59 | outbound TLS-enabled connection in an ACL callout, while not stomping all | |
60 | over the TLS variables available for expansion. | |
059ec3d9 | 61 | |
17c76198 PP |
62 | Some of these correspond to variables in globals.c; those variables will |
63 | be set to point to content in one of these instances, as appropriate for | |
64 | the stage of the process lifetime. | |
059ec3d9 | 65 | |
17c76198 PP |
66 | Not handled here: globals tls_active, tls_bits, tls_cipher, tls_peerdn, |
67 | tls_certificate_verified, tls_channelbinding_b64, tls_sni. | |
68 | */ | |
059ec3d9 | 69 | |
17c76198 PP |
70 | typedef struct exim_gnutls_state { |
71 | gnutls_session_t session; | |
72 | gnutls_certificate_credentials_t x509_cred; | |
73 | gnutls_priority_t priority_cache; | |
74 | enum peer_verify_requirement verify_requirement; | |
75 | int fd_in; | |
76 | int fd_out; | |
77 | BOOL peer_cert_verified; | |
78 | BOOL trigger_sni_changes; | |
79 | const struct host_item *host; | |
80 | uschar *peerdn; | |
81 | uschar *received_sni; | |
82 | ||
83 | const uschar *tls_certificate; | |
84 | const uschar *tls_privatekey; | |
85 | const uschar *tls_sni; /* client send only, not received */ | |
86 | const uschar *tls_verify_certificates; | |
87 | const uschar *tls_crl; | |
88 | const uschar *tls_require_ciphers; | |
89 | uschar *exp_tls_certificate; | |
90 | uschar *exp_tls_privatekey; | |
91 | uschar *exp_tls_sni; | |
92 | uschar *exp_tls_verify_certificates; | |
93 | uschar *exp_tls_crl; | |
94 | uschar *exp_tls_require_ciphers; | |
95 | ||
96 | uschar *xfer_buffer; | |
97 | int xfer_buffer_lwm; | |
98 | int xfer_buffer_hwm; | |
99 | int xfer_eof; | |
100 | int xfer_error; | |
101 | ||
102 | uschar cipherbuf[256]; | |
103 | } exim_gnutls_state_st; | |
104 | ||
105 | static const exim_gnutls_state_st exim_gnutls_state_init = { | |
106 | NULL, NULL, NULL, VERIFY_NONE, -1, -1, FALSE, FALSE, | |
107 | NULL, NULL, NULL, | |
108 | NULL, NULL, NULL, NULL, NULL, NULL, | |
109 | NULL, NULL, NULL, NULL, NULL, NULL, | |
110 | NULL, 0, 0, 0, 0, | |
111 | "" | |
112 | }; | |
83da1223 | 113 | |
17c76198 PP |
114 | /* Not only do we have our own APIs which don't pass around state, assuming |
115 | it's held in globals, GnuTLS doesn't appear to let us register callback data | |
116 | for callbacks, or as part of the session, so we have to keep a "this is the | |
117 | context we're currently dealing with" pointer and rely upon being | |
118 | single-threaded to keep from processing data on an inbound TLS connection while | |
119 | talking to another TLS connection for an outbound check. This does mean that | |
120 | there's no way for heart-beats to be responded to, for the duration of the | |
121 | second connection. */ | |
059ec3d9 | 122 | |
17c76198 PP |
123 | static exim_gnutls_state_st state_server, state_client; |
124 | static exim_gnutls_state_st *current_global_tls_state; | |
059ec3d9 | 125 | |
17c76198 PP |
126 | /* dh_params are initialised once within the lifetime of a process using TLS; |
127 | if we used TLS in a long-lived daemon, we'd have to reconsider this. But we | |
128 | don't want to repeat this. */ | |
83da1223 | 129 | |
17c76198 | 130 | static gnutls_dh_params_t dh_server_params = NULL; |
059ec3d9 | 131 | |
17c76198 | 132 | /* No idea how this value was chosen; preserving it. Default is 3600. */ |
059ec3d9 | 133 | |
17c76198 | 134 | static const int ssl_session_timeout = 200; |
059ec3d9 | 135 | |
17c76198 | 136 | static const char * const exim_default_gnutls_priority = "NORMAL"; |
83da1223 | 137 | |
17c76198 | 138 | /* Guard library core initialisation */ |
83da1223 | 139 | |
17c76198 | 140 | static BOOL exim_gnutls_base_init_done = FALSE; |
059ec3d9 | 141 | |
059ec3d9 | 142 | |
17c76198 PP |
143 | /* ------------------------------------------------------------------------ */ |
144 | /* macros */ | |
83da1223 | 145 | |
17c76198 | 146 | #define MAX_HOST_LEN 255 |
83da1223 | 147 | |
17c76198 PP |
148 | /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup |
149 | the library logging; a value less than 0 disables the calls to set up logging | |
150 | callbacks. */ | |
151 | #define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1 | |
83da1223 | 152 | |
17c76198 | 153 | #define EXIM_CLIENT_DH_MIN_BITS 1024 |
83da1223 | 154 | |
af3498d6 PP |
155 | /* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we |
156 | can ask for a bit-strength. Without that, we stick to the constant we had | |
157 | before, for now. */ | |
158 | #define EXIM_SERVER_DH_BITS_PRE2_12 1024 | |
159 | ||
17c76198 PP |
160 | #define exim_gnutls_err_check(Label) do { \ |
161 | if (rc != GNUTLS_E_SUCCESS) { return tls_error((Label), gnutls_strerror(rc), host); } } while (0) | |
059ec3d9 | 162 | |
17c76198 | 163 | #define expand_check_tlsvar(Varname) expand_check(state->Varname, US #Varname, &state->exp_##Varname) |
83da1223 | 164 | |
17c76198 PP |
165 | #if GNUTLS_VERSION_NUMBER >= 0x020c00 |
166 | #define HAVE_GNUTLS_SESSION_CHANNEL_BINDING | |
af3498d6 PP |
167 | #define HAVE_GNUTLS_SEC_PARAM_CONSTANTS |
168 | #define HAVE_GNUTLS_RND | |
17c76198 | 169 | #endif |
83da1223 | 170 | |
af3498d6 PP |
171 | |
172 | ||
173 | ||
174 | /* ------------------------------------------------------------------------ */ | |
175 | /* Callback declarations */ | |
176 | ||
177 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 | |
178 | static void exim_gnutls_logger_cb(int level, const char *message); | |
179 | #endif | |
180 | ||
181 | static int exim_sni_handling_cb(gnutls_session_t session); | |
182 | ||
183 | ||
184 | ||
185 | ||
17c76198 PP |
186 | /* ------------------------------------------------------------------------ */ |
187 | /* Static functions */ | |
059ec3d9 PH |
188 | |
189 | /************************************************* | |
190 | * Handle TLS error * | |
191 | *************************************************/ | |
192 | ||
193 | /* Called from lots of places when errors occur before actually starting to do | |
194 | the TLS handshake, that is, while the session is still in clear. Always returns | |
195 | DEFER for a server and FAIL for a client so that most calls can use "return | |
196 | tls_error(...)" to do this processing and then give an appropriate return. A | |
197 | single function is used for both server and client, because it is called from | |
198 | some shared functions. | |
199 | ||
200 | Argument: | |
201 | prefix text to include in the logged error | |
7199e1ee TF |
202 | msg additional error string (may be NULL) |
203 | usually obtained from gnutls_strerror() | |
17c76198 PP |
204 | host NULL if setting up a server; |
205 | the connected host if setting up a client | |
059ec3d9 PH |
206 | |
207 | Returns: OK/DEFER/FAIL | |
208 | */ | |
209 | ||
210 | static int | |
17c76198 | 211 | tls_error(const uschar *prefix, const char *msg, const host_item *host) |
059ec3d9 | 212 | { |
17c76198 PP |
213 | if (host) |
214 | { | |
215 | log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s)%s%s", | |
216 | host->name, host->address, prefix, msg ? ": " : "", msg ? msg : ""); | |
217 | return FAIL; | |
218 | } | |
219 | else | |
059ec3d9 | 220 | { |
7199e1ee | 221 | uschar *conn_info = smtp_get_connection_info(); |
17c76198 | 222 | if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) |
7199e1ee TF |
223 | conn_info += 5; |
224 | log_write(0, LOG_MAIN, "TLS error on %s (%s)%s%s", | |
17c76198 | 225 | conn_info, prefix, msg ? ": " : "", msg ? msg : ""); |
059ec3d9 PH |
226 | return DEFER; |
227 | } | |
059ec3d9 PH |
228 | } |
229 | ||
230 | ||
231 | ||
17c76198 | 232 | |
059ec3d9 | 233 | /************************************************* |
17c76198 | 234 | * Deal with logging errors during I/O * |
059ec3d9 PH |
235 | *************************************************/ |
236 | ||
17c76198 | 237 | /* We have to get the identity of the peer from saved data. |
059ec3d9 | 238 | |
17c76198 PP |
239 | Argument: |
240 | state the current GnuTLS exim state container | |
241 | rc the GnuTLS error code, or 0 if it's a local error | |
242 | when text identifying read or write | |
243 | text local error text when ec is 0 | |
059ec3d9 | 244 | |
17c76198 | 245 | Returns: nothing |
059ec3d9 PH |
246 | */ |
247 | ||
17c76198 PP |
248 | static void |
249 | record_io_error(exim_gnutls_state_st *state, int rc, uschar *when, uschar *text) | |
059ec3d9 | 250 | { |
17c76198 | 251 | const char *msg; |
059ec3d9 | 252 | |
17c76198 PP |
253 | if (rc == GNUTLS_E_FATAL_ALERT_RECEIVED) |
254 | msg = CS string_sprintf("%s: %s", US gnutls_strerror(rc), | |
255 | US gnutls_alert_get_name(gnutls_alert_get(state->session))); | |
256 | else | |
257 | msg = gnutls_strerror(rc); | |
059ec3d9 | 258 | |
17c76198 PP |
259 | tls_error(when, msg, state->host); |
260 | } | |
059ec3d9 | 261 | |
059ec3d9 | 262 | |
059ec3d9 | 263 | |
059ec3d9 | 264 | |
17c76198 PP |
265 | /************************************************* |
266 | * Set various Exim expansion vars * | |
267 | *************************************************/ | |
059ec3d9 | 268 | |
17c76198 PP |
269 | /* We set various Exim global variables from the state, once a session has |
270 | been established. With TLS callouts, may need to change this to stack | |
271 | variables, or just re-call it with the server state after client callout | |
272 | has finished. | |
059ec3d9 | 273 | |
17c76198 PP |
274 | Make sure anything set here is inset in tls_getc(). |
275 | ||
276 | Sets: | |
277 | tls_active fd | |
278 | tls_bits strength indicator | |
279 | tls_certificate_verified bool indicator | |
280 | tls_channelbinding_b64 for some SASL mechanisms | |
281 | tls_cipher a string | |
282 | tls_peerdn a string | |
283 | tls_sni a (UTF-8) string | |
284 | Also: | |
285 | current_global_tls_state for API limitations | |
286 | ||
287 | Argument: | |
288 | state the relevant exim_gnutls_state_st * | |
289 | */ | |
290 | ||
291 | static void | |
292 | extract_exim_vars_from_tls_state(exim_gnutls_state_st *state) | |
293 | { | |
294 | gnutls_protocol_t protocol; | |
295 | gnutls_cipher_algorithm_t cipher; | |
296 | gnutls_kx_algorithm_t kx; | |
297 | gnutls_mac_algorithm_t mac; | |
298 | uschar *p; | |
299 | #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING | |
300 | int old_pool; | |
301 | int rc; | |
302 | gnutls_datum_t channel; | |
303 | #endif | |
304 | ||
305 | current_global_tls_state = state; | |
306 | ||
307 | tls_active = state->fd_out; | |
308 | ||
309 | cipher = gnutls_cipher_get(state->session); | |
310 | /* returns size in "bytes" */ | |
311 | tls_bits = gnutls_cipher_get_key_size(cipher) * 8; | |
312 | ||
313 | if (!*state->cipherbuf) | |
059ec3d9 | 314 | { |
17c76198 PP |
315 | protocol = gnutls_protocol_get_version(state->session); |
316 | mac = gnutls_mac_get(state->session); | |
317 | kx = gnutls_kx_get(state->session); | |
318 | ||
319 | string_format(state->cipherbuf, sizeof(state->cipherbuf), | |
320 | "%s:%s:%u", | |
321 | gnutls_protocol_get_name(protocol), | |
322 | gnutls_cipher_suite_get_name(kx, cipher, mac), | |
323 | tls_bits); | |
324 | ||
325 | /* I don't see a way that spaces could occur, in the current GnuTLS | |
326 | code base, but it was a concern in the old code and perhaps older GnuTLS | |
327 | releases did return "TLS 1.0"; play it safe, just in case. */ | |
328 | for (p = state->cipherbuf; *p != '\0'; ++p) | |
329 | if (isspace(*p)) | |
330 | *p = '-'; | |
059ec3d9 | 331 | } |
17c76198 PP |
332 | tls_cipher = state->cipherbuf; |
333 | ||
334 | DEBUG(D_tls) debug_printf("cipher: %s\n", tls_cipher); | |
335 | ||
336 | tls_certificate_verified = state->peer_cert_verified; | |
059ec3d9 | 337 | |
17c76198 PP |
338 | /* note that tls_channelbinding_b64 is not saved to the spool file, since it's |
339 | only available for use for authenticators while this TLS session is running. */ | |
340 | ||
341 | tls_channelbinding_b64 = NULL; | |
342 | #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING | |
343 | channel.data = NULL; | |
344 | channel.size = 0; | |
345 | rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel); | |
346 | if (rc) { | |
347 | DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc)); | |
348 | } else { | |
349 | old_pool = store_pool; | |
350 | store_pool = POOL_PERM; | |
351 | tls_channelbinding_b64 = auth_b64encode(channel.data, (int)channel.size); | |
352 | store_pool = old_pool; | |
353 | DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage.\n"); | |
354 | } | |
355 | #endif | |
356 | ||
357 | tls_peerdn = state->peerdn; | |
358 | ||
359 | tls_sni = state->received_sni; | |
059ec3d9 PH |
360 | } |
361 | ||
362 | ||
363 | ||
17c76198 | 364 | |
059ec3d9 | 365 | /************************************************* |
575643cd | 366 | * Setup up DH parameters * |
059ec3d9 PH |
367 | *************************************************/ |
368 | ||
575643cd | 369 | /* Generating the D-H parameters may take a long time. They only need to |
059ec3d9 PH |
370 | be re-generated every so often, depending on security policy. What we do is to |
371 | keep these parameters in a file in the spool directory. If the file does not | |
372 | exist, we generate them. This means that it is easy to cause a regeneration. | |
373 | ||
374 | The new file is written as a temporary file and renamed, so that an incomplete | |
375 | file is never present. If two processes both compute some new parameters, you | |
376 | waste a bit of effort, but it doesn't seem worth messing around with locking to | |
377 | prevent this. | |
378 | ||
379 | Argument: | |
380 | host NULL for server, server for client (for error handling) | |
381 | ||
382 | Returns: OK/DEFER/FAIL | |
383 | */ | |
384 | ||
385 | static int | |
17c76198 | 386 | init_server_dh(void) |
059ec3d9 | 387 | { |
17c76198 PP |
388 | int fd, rc; |
389 | unsigned int dh_bits; | |
b5aea5e1 | 390 | gnutls_datum m; |
17c76198 PP |
391 | uschar filename[PATH_MAX]; |
392 | size_t sz; | |
393 | host_item *host = NULL; /* dummy for macros */ | |
059ec3d9 | 394 | |
17c76198 | 395 | DEBUG(D_tls) debug_printf("Initialising GnuTLS server params.\n"); |
059ec3d9 | 396 | |
17c76198 PP |
397 | rc = gnutls_dh_params_init(&dh_server_params); |
398 | exim_gnutls_err_check(US"gnutls_dh_params_init"); | |
059ec3d9 | 399 | |
af3498d6 PP |
400 | #ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS |
401 | /* If you change this constant, also change dh_param_fn_ext so that we can use a | |
17c76198 PP |
402 | different filename and ensure we have sufficient bits. */ |
403 | dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, GNUTLS_SEC_PARAM_NORMAL); | |
404 | if (!dh_bits) | |
405 | return tls_error(US"gnutls_sec_param_to_pk_bits() failed", NULL, NULL); | |
af3498d6 | 406 | DEBUG(D_tls) |
b34fc30c | 407 | debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits.\n", |
af3498d6 PP |
408 | dh_bits); |
409 | #else | |
410 | dh_bits = EXIM_SERVER_DH_BITS_PRE2_12; | |
411 | DEBUG(D_tls) | |
412 | debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits.\n", | |
413 | dh_bits); | |
414 | #endif | |
059ec3d9 | 415 | |
17c76198 | 416 | if (!string_format(filename, sizeof(filename), |
af3498d6 | 417 | "%s/gnutls-params-%d", spool_directory, dh_bits)) |
17c76198 | 418 | return tls_error(US"overlong filename", NULL, NULL); |
059ec3d9 | 419 | |
b5aea5e1 | 420 | /* Open the cache file for reading and if successful, read it and set up the |
575643cd | 421 | parameters. */ |
059ec3d9 PH |
422 | |
423 | fd = Uopen(filename, O_RDONLY, 0); | |
b5aea5e1 | 424 | if (fd >= 0) |
059ec3d9 | 425 | { |
b5aea5e1 | 426 | struct stat statbuf; |
17c76198 PP |
427 | FILE *fp; |
428 | int saved_errno; | |
429 | ||
430 | if (fstat(fd, &statbuf) < 0) /* EIO */ | |
431 | { | |
432 | saved_errno = errno; | |
433 | (void)close(fd); | |
434 | return tls_error(US"TLS cache stat failed", strerror(saved_errno), NULL); | |
435 | } | |
436 | if (!S_ISREG(statbuf.st_mode)) | |
b5aea5e1 PH |
437 | { |
438 | (void)close(fd); | |
17c76198 PP |
439 | return tls_error(US"TLS cache not a file", NULL, NULL); |
440 | } | |
441 | fp = fdopen(fd, "rb"); | |
442 | if (!fp) | |
443 | { | |
444 | saved_errno = errno; | |
445 | (void)close(fd); | |
446 | return tls_error(US"fdopen(TLS cache stat fd) failed", | |
447 | strerror(saved_errno), NULL); | |
b5aea5e1 | 448 | } |
059ec3d9 | 449 | |
b5aea5e1 PH |
450 | m.size = statbuf.st_size; |
451 | m.data = malloc(m.size); | |
452 | if (m.data == NULL) | |
17c76198 PP |
453 | { |
454 | fclose(fp); | |
455 | return tls_error(US"malloc failed", strerror(errno), NULL); | |
456 | } | |
457 | sz = fread(m.data, m.size, 1, fp); | |
458 | if (!sz) | |
459 | { | |
460 | saved_errno = errno; | |
461 | fclose(fp); | |
462 | free(m.data); | |
463 | return tls_error(US"fread failed", strerror(saved_errno), NULL); | |
464 | } | |
465 | fclose(fp); | |
b5aea5e1 | 466 | |
17c76198 | 467 | rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM); |
b5aea5e1 | 468 | free(m.data); |
17c76198 PP |
469 | exim_gnutls_err_check(US"gnutls_dh_params_import_pkcs3"); |
470 | DEBUG(D_tls) debug_printf("read D-H parameters from file \"%s\"\n", filename); | |
b5aea5e1 PH |
471 | } |
472 | ||
473 | /* If the file does not exist, fall through to compute new data and cache it. | |
474 | If there was any other opening error, it is serious. */ | |
475 | ||
182ad5cf PH |
476 | else if (errno == ENOENT) |
477 | { | |
17c76198 | 478 | rc = -1; |
182ad5cf | 479 | DEBUG(D_tls) |
17c76198 | 480 | debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename); |
182ad5cf PH |
481 | } |
482 | else | |
17c76198 PP |
483 | return tls_error(string_open_failed(errno, "\"%s\" for reading", filename), |
484 | NULL, NULL); | |
b5aea5e1 PH |
485 | |
486 | /* If ret < 0, either the cache file does not exist, or the data it contains | |
487 | is not useful. One particular case of this is when upgrading from an older | |
488 | release of Exim in which the data was stored in a different format. We don't | |
489 | try to be clever and support both formats; we just regenerate new data in this | |
490 | case. */ | |
491 | ||
17c76198 | 492 | if (rc < 0) |
b5aea5e1 | 493 | { |
17c76198 | 494 | uschar *temp_fn; |
059ec3d9 | 495 | |
17c76198 PP |
496 | if ((PATH_MAX - Ustrlen(filename)) < 10) |
497 | return tls_error(US"Filename too long to generate replacement", | |
498 | CS filename, NULL); | |
059ec3d9 | 499 | |
17c76198 PP |
500 | temp_fn = string_copy(US "%s.XXXXXXX"); |
501 | fd = mkstemp(CS temp_fn); /* modifies temp_fn */ | |
059ec3d9 | 502 | if (fd < 0) |
17c76198 | 503 | return tls_error(US"Unable to open temp file", strerror(errno), NULL); |
059ec3d9 PH |
504 | (void)fchown(fd, exim_uid, exim_gid); /* Probably not necessary */ |
505 | ||
17c76198 PP |
506 | DEBUG(D_tls) debug_printf("generating %d bits Diffie-Hellman key ...\n", dh_bits); |
507 | rc = gnutls_dh_params_generate2(dh_server_params, dh_bits); | |
508 | exim_gnutls_err_check(US"gnutls_dh_params_generate2"); | |
509 | ||
510 | /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time, | |
511 | and I confirmed that a NULL call to get the size first is how the GnuTLS | |
512 | sample apps handle this. */ | |
513 | ||
514 | sz = 0; | |
515 | m.data = NULL; | |
516 | rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM, | |
517 | m.data, &sz); | |
518 | if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER) | |
519 | exim_gnutls_err_check(US"gnutls_dh_params_export_pkcs3(NULL) sizing"); | |
520 | m.size = sz; | |
b5aea5e1 PH |
521 | m.data = malloc(m.size); |
522 | if (m.data == NULL) | |
17c76198 PP |
523 | return tls_error(US"memory allocation failed", strerror(errno), NULL); |
524 | rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM, | |
525 | m.data, &sz); | |
526 | if (rc != GNUTLS_E_SUCCESS) | |
527 | { | |
528 | free(m.data); | |
529 | exim_gnutls_err_check(US"gnutls_dh_params_export_pkcs3() real"); | |
530 | } | |
059ec3d9 | 531 | |
17c76198 PP |
532 | sz = write_to_fd_buf(fd, m.data, (size_t) m.size); |
533 | if (sz != m.size) | |
534 | { | |
535 | free(m.data); | |
536 | return tls_error(US"TLS cache write D-H params failed", | |
537 | strerror(errno), NULL); | |
538 | } | |
b5aea5e1 | 539 | free(m.data); |
17c76198 PP |
540 | sz = write_to_fd_buf(fd, US"\n", 1); |
541 | if (sz != 1) | |
542 | return tls_error(US"TLS cache write D-H params final newline failed", | |
543 | strerror(errno), NULL); | |
544 | ||
545 | rc = close(fd); | |
546 | if (rc) | |
547 | return tls_error(US"TLS cache write close() failed", | |
548 | strerror(errno), NULL); | |
059ec3d9 | 549 | |
17c76198 PP |
550 | if (Urename(temp_fn, filename) < 0) |
551 | return tls_error(string_sprintf("failed to rename \"%s\" as \"%s\"", | |
552 | temp_fn, filename), strerror(errno), NULL); | |
059ec3d9 | 553 | |
17c76198 | 554 | DEBUG(D_tls) debug_printf("wrote D-H parameters to file \"%s\"\n", filename); |
059ec3d9 PH |
555 | } |
556 | ||
17c76198 | 557 | DEBUG(D_tls) debug_printf("initialized server D-H parameters\n"); |
059ec3d9 PH |
558 | return OK; |
559 | } | |
560 | ||
561 | ||
562 | ||
563 | ||
564 | /************************************************* | |
17c76198 | 565 | * Variables re-expanded post-SNI * |
059ec3d9 PH |
566 | *************************************************/ |
567 | ||
17c76198 PP |
568 | /* Called from both server and client code, via tls_init(), and also from |
569 | the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni". | |
570 | ||
571 | We can tell the two apart by state->received_sni being non-NULL in callback. | |
572 | ||
573 | The callback should not call us unless state->trigger_sni_changes is true, | |
574 | which we are responsible for setting on the first pass through. | |
059ec3d9 PH |
575 | |
576 | Arguments: | |
17c76198 | 577 | state exim_gnutls_state_st * |
059ec3d9 PH |
578 | |
579 | Returns: OK/DEFER/FAIL | |
580 | */ | |
581 | ||
582 | static int | |
17c76198 | 583 | tls_expand_session_files(exim_gnutls_state_st *state) |
059ec3d9 | 584 | { |
1365611d | 585 | struct stat statbuf; |
059ec3d9 | 586 | int rc; |
17c76198 PP |
587 | const host_item *host = state->host; /* macro should be reconsidered? */ |
588 | uschar *saved_tls_certificate = NULL; | |
589 | uschar *saved_tls_privatekey = NULL; | |
590 | uschar *saved_tls_verify_certificates = NULL; | |
591 | uschar *saved_tls_crl = NULL; | |
592 | int cert_count; | |
593 | ||
594 | /* We check for tls_sni *before* expansion. */ | |
595 | if (!state->host) | |
596 | { | |
597 | if (!state->received_sni) | |
598 | { | |
599 | if (Ustrstr(state->tls_certificate, US"tls_sni")) | |
600 | { | |
601 | DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI.\n"); | |
602 | state->trigger_sni_changes = TRUE; | |
603 | } | |
604 | } | |
605 | else | |
606 | { | |
1365611d | 607 | /* useful for debugging */ |
17c76198 PP |
608 | saved_tls_certificate = state->exp_tls_certificate; |
609 | saved_tls_privatekey = state->exp_tls_privatekey; | |
610 | saved_tls_verify_certificates = state->exp_tls_verify_certificates; | |
611 | saved_tls_crl = state->exp_tls_crl; | |
612 | } | |
613 | } | |
059ec3d9 | 614 | |
1365611d PP |
615 | rc = gnutls_certificate_allocate_credentials(&state->x509_cred); |
616 | exim_gnutls_err_check(US"gnutls_certificate_allocate_credentials"); | |
617 | ||
17c76198 PP |
618 | /* remember: expand_check_tlsvar() is expand_check() but fiddling with |
619 | state members, assuming consistent naming; and expand_check() returns | |
620 | false if expansion failed, unless expansion was forced to fail. */ | |
059ec3d9 | 621 | |
17c76198 PP |
622 | /* check if we at least have a certificate, before doing expensive |
623 | D-H generation. */ | |
059ec3d9 | 624 | |
17c76198 PP |
625 | if (!expand_check_tlsvar(tls_certificate)) |
626 | return DEFER; | |
059ec3d9 | 627 | |
17c76198 | 628 | /* certificate is mandatory in server, optional in client */ |
059ec3d9 | 629 | |
17c76198 PP |
630 | if ((state->exp_tls_certificate == NULL) || |
631 | (*state->exp_tls_certificate == '\0')) | |
632 | { | |
633 | if (state->host == NULL) | |
634 | return tls_error(US"no TLS server certificate is specified", NULL, NULL); | |
635 | else | |
636 | DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n"); | |
637 | } | |
059ec3d9 | 638 | |
17c76198 | 639 | if (state->tls_privatekey && !expand_check_tlsvar(tls_privatekey)) |
059ec3d9 PH |
640 | return DEFER; |
641 | ||
17c76198 PP |
642 | /* tls_privatekey is optional, defaulting to same file as certificate */ |
643 | ||
644 | if (state->tls_privatekey == NULL || *state->tls_privatekey == '\0') | |
059ec3d9 | 645 | { |
17c76198 PP |
646 | state->tls_privatekey = state->tls_certificate; |
647 | state->exp_tls_privatekey = state->exp_tls_certificate; | |
059ec3d9 | 648 | } |
c91535f3 | 649 | |
059ec3d9 | 650 | |
17c76198 | 651 | if (state->exp_tls_certificate && *state->exp_tls_certificate) |
059ec3d9 PH |
652 | { |
653 | DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n", | |
17c76198 PP |
654 | state->exp_tls_certificate, state->exp_tls_privatekey); |
655 | ||
656 | if (state->received_sni) | |
de365ded | 657 | { |
17c76198 PP |
658 | if ((Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0) && |
659 | (Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0)) | |
660 | { | |
b34fc30c | 661 | DEBUG(D_tls) debug_printf("TLS SNI: cert and key unchanged\n"); |
17c76198 PP |
662 | } |
663 | else | |
664 | { | |
b34fc30c | 665 | DEBUG(D_tls) debug_printf("TLS SNI: have a changed cert/key pair.\n"); |
17c76198 | 666 | } |
8e669ac1 | 667 | } |
059ec3d9 | 668 | |
1365611d PP |
669 | rc = gnutls_certificate_set_x509_key_file(state->x509_cred, |
670 | CS state->exp_tls_certificate, CS state->exp_tls_privatekey, | |
671 | GNUTLS_X509_FMT_PEM); | |
672 | exim_gnutls_err_check( | |
673 | string_sprintf("cert/key setup: cert=%s key=%s", | |
674 | state->exp_tls_certificate, state->exp_tls_privatekey)); | |
675 | DEBUG(D_tls) debug_printf("TLS: cert/key registered\n"); | |
b34fc30c | 676 | } /* tls_certificate */ |
059ec3d9 PH |
677 | |
678 | /* Set the trusted CAs file if one is provided, and then add the CRL if one is | |
679 | provided. Experiment shows that, if the certificate file is empty, an unhelpful | |
680 | error message is provided. However, if we just refrain from setting anything up | |
681 | in that case, certificate verification fails, which seems to be the correct | |
682 | behaviour. */ | |
683 | ||
17c76198 | 684 | if (state->tls_verify_certificates && *state->tls_verify_certificates) |
059ec3d9 | 685 | { |
17c76198 | 686 | if (!expand_check_tlsvar(tls_verify_certificates)) |
059ec3d9 | 687 | return DEFER; |
17c76198 PP |
688 | if (state->tls_crl && *state->tls_crl) |
689 | if (!expand_check_tlsvar(tls_crl)) | |
690 | return DEFER; | |
059ec3d9 | 691 | |
1365611d PP |
692 | if (!(state->exp_tls_verify_certificates && |
693 | *state->exp_tls_verify_certificates)) | |
b34fc30c PP |
694 | { |
695 | DEBUG(D_tls) | |
1365611d PP |
696 | debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n"); |
697 | /* With no tls_verify_certificates, we ignore tls_crl too */ | |
17c76198 | 698 | return OK; |
b34fc30c | 699 | } |
1365611d | 700 | } |
83e2f8a2 PP |
701 | else |
702 | { | |
703 | DEBUG(D_tls) | |
704 | debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n"); | |
705 | return OK; | |
706 | } | |
17c76198 | 707 | |
1365611d PP |
708 | if (Ustat(state->exp_tls_verify_certificates, &statbuf) < 0) |
709 | { | |
710 | log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s " | |
711 | "(tls_verify_certificates): %s", state->exp_tls_verify_certificates, | |
712 | strerror(errno)); | |
713 | return DEFER; | |
714 | } | |
17c76198 | 715 | |
1365611d PP |
716 | if (!S_ISREG(statbuf.st_mode)) |
717 | { | |
718 | DEBUG(D_tls) | |
719 | debug_printf("verify certificates path is not a file: \"%s\"\n%s\n", | |
720 | state->exp_tls_verify_certificates, | |
721 | S_ISDIR(statbuf.st_mode) | |
722 | ? " it's a directory, that's OpenSSL, this is GnuTLS" | |
723 | : " (not a directory either)"); | |
724 | log_write(0, LOG_MAIN|LOG_PANIC, | |
725 | "tls_verify_certificates \"%s\" is not a file", | |
726 | state->exp_tls_verify_certificates); | |
727 | return DEFER; | |
728 | } | |
059ec3d9 | 729 | |
1365611d PP |
730 | DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n", |
731 | state->exp_tls_verify_certificates, statbuf.st_size); | |
059ec3d9 | 732 | |
1365611d PP |
733 | if (statbuf.st_size == 0) |
734 | { | |
735 | DEBUG(D_tls) | |
736 | debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n"); | |
737 | return OK; | |
738 | } | |
059ec3d9 | 739 | |
1365611d PP |
740 | cert_count = gnutls_certificate_set_x509_trust_file(state->x509_cred, |
741 | CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM); | |
742 | if (cert_count < 0) | |
743 | { | |
744 | rc = cert_count; | |
745 | exim_gnutls_err_check(US"gnutls_certificate_set_x509_trust_file"); | |
746 | } | |
747 | DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n", cert_count); | |
059ec3d9 | 748 | |
1365611d PP |
749 | if (state->tls_crl && *state->tls_crl) |
750 | { | |
751 | if (state->exp_tls_crl && *state->exp_tls_crl) | |
752 | { | |
753 | DEBUG(D_tls) debug_printf("loading CRL file = %s\n", state->exp_tls_crl); | |
754 | rc = gnutls_certificate_set_x509_crl_file(state->x509_cred, | |
755 | CS state->exp_tls_crl, GNUTLS_X509_FMT_PEM); | |
756 | exim_gnutls_err_check(US"gnutls_certificate_set_x509_crl_file"); | |
757 | } | |
758 | } | |
059ec3d9 | 759 | |
059ec3d9 PH |
760 | return OK; |
761 | } | |
762 | ||
763 | ||
764 | ||
765 | ||
1365611d PP |
766 | /************************************************* |
767 | * Set X.509 state variables * | |
768 | *************************************************/ | |
769 | ||
770 | /* In GnuTLS, the registered cert/key are not replaced by a later | |
771 | set of a cert/key, so for SNI support we need a whole new x509_cred | |
772 | structure. Which means various other non-re-expanded pieces of state | |
773 | need to be re-set in the new struct, so the setting logic is pulled | |
774 | out to this. | |
775 | ||
776 | Arguments: | |
777 | state exim_gnutls_state_st * | |
778 | ||
779 | Returns: OK/DEFER/FAIL | |
780 | */ | |
781 | ||
782 | static int | |
783 | tls_set_remaining_x509(exim_gnutls_state_st *state) | |
784 | { | |
785 | int rc; | |
786 | const host_item *host = state->host; /* macro should be reconsidered? */ | |
787 | ||
788 | /* Create D-H parameters, or read them from the cache file. This function does | |
789 | its own SMTP error messaging. This only happens for the server, TLS D-H ignores | |
790 | client-side params. */ | |
791 | ||
792 | if (!state->host) | |
793 | { | |
794 | if (!dh_server_params) | |
795 | { | |
796 | rc = init_server_dh(); | |
797 | if (rc != OK) return rc; | |
798 | } | |
799 | gnutls_certificate_set_dh_params(state->x509_cred, dh_server_params); | |
800 | } | |
801 | ||
802 | /* Link the credentials to the session. */ | |
803 | ||
804 | rc = gnutls_credentials_set(state->session, GNUTLS_CRD_CERTIFICATE, state->x509_cred); | |
805 | exim_gnutls_err_check(US"gnutls_credentials_set"); | |
806 | ||
807 | return OK; | |
808 | } | |
809 | ||
059ec3d9 | 810 | /************************************************* |
17c76198 | 811 | * Initialize for GnuTLS * |
059ec3d9 PH |
812 | *************************************************/ |
813 | ||
17c76198 PP |
814 | /* Called from both server and client code. In the case of a server, errors |
815 | before actual TLS negotiation return DEFER. | |
059ec3d9 PH |
816 | |
817 | Arguments: | |
17c76198 PP |
818 | host connected host, if client; NULL if server |
819 | certificate certificate file | |
820 | privatekey private key file | |
821 | sni TLS SNI to send, sometimes when client; else NULL | |
822 | cas CA certs file | |
823 | crl CRL file | |
824 | require_ciphers tls_require_ciphers setting | |
059ec3d9 | 825 | |
17c76198 | 826 | Returns: OK/DEFER/FAIL |
059ec3d9 PH |
827 | */ |
828 | ||
17c76198 PP |
829 | static int |
830 | tls_init( | |
831 | const host_item *host, | |
832 | const uschar *certificate, | |
833 | const uschar *privatekey, | |
834 | const uschar *sni, | |
835 | const uschar *cas, | |
836 | const uschar *crl, | |
837 | const uschar *require_ciphers, | |
838 | exim_gnutls_state_st **caller_state) | |
059ec3d9 | 839 | { |
17c76198 PP |
840 | exim_gnutls_state_st *state; |
841 | int rc; | |
842 | size_t sz; | |
843 | const char *errpos; | |
844 | uschar *p; | |
845 | BOOL want_default_priorities; | |
846 | ||
847 | if (!exim_gnutls_base_init_done) | |
059ec3d9 | 848 | { |
17c76198 PP |
849 | DEBUG(D_tls) debug_printf("GnuTLS global init required.\n"); |
850 | ||
851 | rc = gnutls_global_init(); | |
852 | exim_gnutls_err_check(US"gnutls_global_init"); | |
853 | ||
854 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 | |
855 | DEBUG(D_tls) | |
059ec3d9 | 856 | { |
17c76198 PP |
857 | gnutls_global_set_log_function(exim_gnutls_logger_cb); |
858 | /* arbitrarily chosen level; bump upto 9 for more */ | |
859 | gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL); | |
059ec3d9 | 860 | } |
17c76198 PP |
861 | #endif |
862 | ||
863 | exim_gnutls_base_init_done = TRUE; | |
059ec3d9 | 864 | } |
059ec3d9 | 865 | |
17c76198 PP |
866 | if (host) |
867 | { | |
868 | state = &state_client; | |
869 | memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); | |
870 | DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n"); | |
871 | rc = gnutls_init(&state->session, GNUTLS_CLIENT); | |
872 | } | |
873 | else | |
874 | { | |
875 | state = &state_server; | |
876 | memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); | |
877 | DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n"); | |
878 | rc = gnutls_init(&state->session, GNUTLS_SERVER); | |
879 | } | |
880 | exim_gnutls_err_check(US"gnutls_init"); | |
059ec3d9 | 881 | |
17c76198 | 882 | state->host = host; |
059ec3d9 | 883 | |
17c76198 PP |
884 | state->tls_certificate = certificate; |
885 | state->tls_privatekey = privatekey; | |
886 | state->tls_sni = sni; | |
887 | state->tls_verify_certificates = cas; | |
888 | state->tls_crl = crl; | |
059ec3d9 | 889 | |
17c76198 PP |
890 | /* This handles the variables that might get re-expanded after TLS SNI; |
891 | that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */ | |
059ec3d9 | 892 | |
17c76198 PP |
893 | DEBUG(D_tls) |
894 | debug_printf("Expanding various TLS configuration options for session credentials.\n"); | |
895 | rc = tls_expand_session_files(state); | |
896 | if (rc != OK) return rc; | |
059ec3d9 | 897 | |
1365611d PP |
898 | /* These are all other parts of the x509_cred handling, since SNI in GnuTLS |
899 | requires a new structure afterwards. */ | |
83da1223 | 900 | |
1365611d PP |
901 | rc = tls_set_remaining_x509(state); |
902 | if (rc != OK) return rc; | |
83da1223 | 903 | |
17c76198 PP |
904 | /* set SNI in client, only */ |
905 | if (host) | |
906 | { | |
907 | if (!expand_check_tlsvar(tls_sni)) | |
908 | return DEFER; | |
909 | if (state->exp_tls_sni && *state->exp_tls_sni) | |
910 | { | |
911 | DEBUG(D_tls) | |
912 | debug_printf("Setting TLS client SNI to \"%s\"\n", state->exp_tls_sni); | |
913 | sz = Ustrlen(state->exp_tls_sni); | |
914 | rc = gnutls_server_name_set(state->session, | |
915 | GNUTLS_NAME_DNS, state->exp_tls_sni, sz); | |
916 | exim_gnutls_err_check(US"gnutls_server_name_set"); | |
917 | } | |
918 | } | |
919 | else if (state->tls_sni) | |
920 | DEBUG(D_tls) debug_printf("*** PROBABLY A BUG *** " \ | |
921 | "have an SNI set for a client [%s]\n", state->tls_sni); | |
83da1223 | 922 | |
17c76198 PP |
923 | /* This is the priority string support, |
924 | http://www.gnu.org/software/gnutls/manual/html_node/Priority-Strings.html | |
925 | and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols. | |
926 | This was backwards incompatible, but means Exim no longer needs to track | |
927 | all algorithms and provide string forms for them. */ | |
83da1223 | 928 | |
17c76198 | 929 | want_default_priorities = TRUE; |
83da1223 | 930 | |
17c76198 | 931 | if (state->tls_require_ciphers && *state->tls_require_ciphers) |
83da1223 | 932 | { |
17c76198 PP |
933 | if (!expand_check_tlsvar(tls_require_ciphers)) |
934 | return DEFER; | |
935 | if (state->exp_tls_require_ciphers && *state->exp_tls_require_ciphers) | |
83da1223 | 936 | { |
17c76198 PP |
937 | DEBUG(D_tls) debug_printf("GnuTLS session cipher/priority \"%s\"\n", |
938 | state->exp_tls_require_ciphers); | |
939 | ||
940 | rc = gnutls_priority_init(&state->priority_cache, | |
941 | CS state->exp_tls_require_ciphers, &errpos); | |
942 | want_default_priorities = FALSE; | |
943 | p = state->exp_tls_require_ciphers; | |
83da1223 PH |
944 | } |
945 | } | |
17c76198 PP |
946 | if (want_default_priorities) |
947 | { | |
83e2f8a2 PP |
948 | DEBUG(D_tls) |
949 | debug_printf("GnuTLS using default session cipher/priority \"%s\"\n", | |
950 | exim_default_gnutls_priority); | |
17c76198 PP |
951 | rc = gnutls_priority_init(&state->priority_cache, |
952 | exim_default_gnutls_priority, &errpos); | |
953 | p = US exim_default_gnutls_priority; | |
954 | } | |
83da1223 | 955 | |
17c76198 PP |
956 | exim_gnutls_err_check(string_sprintf( |
957 | "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"", | |
958 | p, errpos - CS p, errpos)); | |
959 | ||
960 | rc = gnutls_priority_set(state->session, state->priority_cache); | |
961 | exim_gnutls_err_check(US"gnutls_priority_set"); | |
962 | ||
963 | gnutls_db_set_cache_expiration(state->session, ssl_session_timeout); | |
964 | ||
965 | /* Reduce security in favour of increased compatibility, if the admin | |
966 | decides to make that trade-off. */ | |
967 | if (gnutls_compat_mode) | |
83da1223 | 968 | { |
17c76198 PP |
969 | #if LIBGNUTLS_VERSION_NUMBER >= 0x020104 |
970 | DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n"); | |
971 | gnutls_session_enable_compatibility_mode(state->session); | |
972 | #else | |
973 | DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n"); | |
974 | #endif | |
83da1223 PH |
975 | } |
976 | ||
17c76198 PP |
977 | *caller_state = state; |
978 | /* needs to happen before callbacks during handshake */ | |
979 | current_global_tls_state = state; | |
980 | return OK; | |
83da1223 PH |
981 | } |
982 | ||
983 | ||
984 | ||
985 | ||
059ec3d9 | 986 | /************************************************* |
17c76198 | 987 | * Extract peer information * |
059ec3d9 PH |
988 | *************************************************/ |
989 | ||
17c76198 PP |
990 | /* Called from both server and client code. |
991 | Only this is allowed to set state->peerdn and we use that to detect double-calls. | |
059ec3d9 PH |
992 | |
993 | Arguments: | |
17c76198 | 994 | state exim_gnutls_state_st * |
059ec3d9 | 995 | |
17c76198 | 996 | Returns: OK/DEFER/FAIL |
059ec3d9 PH |
997 | */ |
998 | ||
17c76198 PP |
999 | static int |
1000 | peer_status(exim_gnutls_state_st *state) | |
059ec3d9 | 1001 | { |
17c76198 PP |
1002 | const gnutls_datum *cert_list; |
1003 | int rc; | |
1004 | unsigned int cert_list_size = 0; | |
1005 | gnutls_certificate_type_t ct; | |
1006 | gnutls_x509_crt_t crt; | |
1007 | uschar *dn_buf; | |
1008 | size_t sz; | |
059ec3d9 | 1009 | |
17c76198 PP |
1010 | if (state->peerdn) |
1011 | return OK; | |
059ec3d9 | 1012 | |
17c76198 | 1013 | state->peerdn = US"unknown"; |
059ec3d9 | 1014 | |
17c76198 | 1015 | cert_list = gnutls_certificate_get_peers(state->session, &cert_list_size); |
83da1223 | 1016 | |
17c76198 PP |
1017 | if (cert_list == NULL || cert_list_size == 0) |
1018 | { | |
1019 | state->peerdn = US"unknown (no certificate)"; | |
1020 | DEBUG(D_tls) debug_printf("TLS: no certificate from peer (%p & %d)\n", | |
1021 | cert_list, cert_list_size); | |
1022 | if (state->verify_requirement == VERIFY_REQUIRED) | |
1023 | return tls_error(US"certificate verification failed", | |
1024 | "no certificate received from peer", state->host); | |
1025 | return OK; | |
1026 | } | |
059ec3d9 | 1027 | |
17c76198 PP |
1028 | ct = gnutls_certificate_type_get(state->session); |
1029 | if (ct != GNUTLS_CRT_X509) | |
059ec3d9 | 1030 | { |
17c76198 PP |
1031 | const char *ctn = gnutls_certificate_type_get_name(ct); |
1032 | state->peerdn = string_sprintf("unknown (type %s)", ctn); | |
1033 | DEBUG(D_tls) | |
1034 | debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn); | |
1035 | if (state->verify_requirement == VERIFY_REQUIRED) | |
1036 | return tls_error(US"certificate verification not possible, unhandled type", | |
1037 | ctn, state->host); | |
1038 | return OK; | |
83da1223 | 1039 | } |
059ec3d9 | 1040 | |
17c76198 PP |
1041 | #define exim_gnutls_peer_err(Label) do { \ |
1042 | if (rc != GNUTLS_E_SUCCESS) { \ | |
1043 | DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", (Label), gnutls_strerror(rc)); \ | |
1044 | if (state->verify_requirement == VERIFY_REQUIRED) { return tls_error((Label), gnutls_strerror(rc), state->host); } \ | |
1045 | return OK; } } while (0) | |
1046 | ||
1047 | rc = gnutls_x509_crt_init(&crt); | |
1048 | exim_gnutls_peer_err(US"gnutls_x509_crt_init (crt)"); | |
1049 | ||
1050 | rc = gnutls_x509_crt_import(crt, &cert_list[0], GNUTLS_X509_FMT_DER); | |
1051 | exim_gnutls_peer_err(US"failed to import certificate [gnutls_x509_crt_import(cert 0)]"); | |
1052 | sz = 0; | |
1053 | rc = gnutls_x509_crt_get_dn(crt, NULL, &sz); | |
1054 | if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER) | |
83da1223 | 1055 | { |
17c76198 PP |
1056 | exim_gnutls_peer_err(US"getting size for cert DN failed"); |
1057 | return FAIL; /* should not happen */ | |
059ec3d9 | 1058 | } |
17c76198 PP |
1059 | dn_buf = store_get_perm(sz); |
1060 | rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz); | |
1061 | exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]"); | |
1062 | state->peerdn = dn_buf; | |
1063 | ||
1064 | return OK; | |
1065 | #undef exim_gnutls_peer_err | |
1066 | } | |
059ec3d9 | 1067 | |
059ec3d9 | 1068 | |
059ec3d9 | 1069 | |
059ec3d9 | 1070 | |
17c76198 PP |
1071 | /************************************************* |
1072 | * Verify peer certificate * | |
1073 | *************************************************/ | |
059ec3d9 | 1074 | |
17c76198 PP |
1075 | /* Called from both server and client code. |
1076 | *Should* be using a callback registered with | |
1077 | gnutls_certificate_set_verify_function() to fail the handshake if we dislike | |
1078 | the peer information, but that's too new for some OSes. | |
059ec3d9 | 1079 | |
17c76198 PP |
1080 | Arguments: |
1081 | state exim_gnutls_state_st * | |
1082 | error where to put an error message | |
059ec3d9 | 1083 | |
17c76198 PP |
1084 | Returns: |
1085 | FALSE if the session should be rejected | |
1086 | TRUE if the cert is okay or we just don't care | |
1087 | */ | |
059ec3d9 | 1088 | |
17c76198 PP |
1089 | static BOOL |
1090 | verify_certificate(exim_gnutls_state_st *state, const char **error) | |
1091 | { | |
1092 | int rc; | |
1093 | unsigned int verify; | |
1094 | ||
1095 | *error = NULL; | |
1096 | ||
1097 | rc = peer_status(state); | |
1098 | if (rc != OK) | |
e6060e2c | 1099 | { |
17c76198 PP |
1100 | verify = GNUTLS_CERT_INVALID; |
1101 | *error = "not supplied"; | |
1102 | } | |
1103 | else | |
1104 | { | |
1105 | rc = gnutls_certificate_verify_peers2(state->session, &verify); | |
e6060e2c NM |
1106 | } |
1107 | ||
17c76198 PP |
1108 | /* Handle the result of verification. INVALID seems to be set as well |
1109 | as REVOKED, but leave the test for both. */ | |
059ec3d9 | 1110 | |
17c76198 PP |
1111 | if ((rc < 0) || (verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED)) != 0) |
1112 | { | |
1113 | state->peer_cert_verified = FALSE; | |
1114 | if (*error == NULL) | |
1115 | *error = ((verify & GNUTLS_CERT_REVOKED) != 0) ? "revoked" : "invalid"; | |
059ec3d9 | 1116 | |
17c76198 PP |
1117 | DEBUG(D_tls) |
1118 | debug_printf("TLS certificate verification failed (%s): peerdn=%s\n", | |
1119 | *error, state->peerdn); | |
059ec3d9 | 1120 | |
17c76198 PP |
1121 | if (state->verify_requirement == VERIFY_REQUIRED) |
1122 | { | |
1123 | gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE); | |
1124 | return FALSE; | |
1125 | } | |
1126 | DEBUG(D_tls) | |
1127 | debug_printf("TLS verify failure overriden (host in tls_try_verify_hosts)\n"); | |
1128 | } | |
1129 | else | |
1130 | { | |
1131 | state->peer_cert_verified = TRUE; | |
1132 | DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=%s\n", state->peerdn); | |
1133 | } | |
059ec3d9 | 1134 | |
17c76198 | 1135 | tls_peerdn = state->peerdn; |
059ec3d9 | 1136 | |
17c76198 PP |
1137 | return TRUE; |
1138 | } | |
059ec3d9 | 1139 | |
17c76198 PP |
1140 | |
1141 | ||
1142 | ||
1143 | /* ------------------------------------------------------------------------ */ | |
1144 | /* Callbacks */ | |
1145 | ||
1146 | /* Logging function which can be registered with | |
1147 | * gnutls_global_set_log_function() | |
1148 | * gnutls_global_set_log_level() 0..9 | |
1149 | */ | |
af3498d6 | 1150 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 |
059ec3d9 | 1151 | static void |
17c76198 | 1152 | exim_gnutls_logger_cb(int level, const char *message) |
059ec3d9 | 1153 | { |
17c76198 PP |
1154 | DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s\n", level, message); |
1155 | } | |
af3498d6 | 1156 | #endif |
059ec3d9 | 1157 | |
059ec3d9 | 1158 | |
17c76198 PP |
1159 | /* Called after client hello, should handle SNI work. |
1160 | This will always set tls_sni (state->received_sni) if available, | |
1161 | and may trigger presenting different certificates, | |
1162 | if state->trigger_sni_changes is TRUE. | |
059ec3d9 | 1163 | |
17c76198 PP |
1164 | Should be registered with |
1165 | gnutls_handshake_set_post_client_hello_function() | |
059ec3d9 | 1166 | |
17c76198 PP |
1167 | "This callback must return 0 on success or a gnutls error code to terminate the |
1168 | handshake.". | |
059ec3d9 | 1169 | |
17c76198 PP |
1170 | For inability to get SNI information, we return 0. |
1171 | We only return non-zero if re-setup failed. | |
1172 | */ | |
44bbabb5 | 1173 | |
17c76198 PP |
1174 | static int |
1175 | exim_sni_handling_cb(gnutls_session_t session) | |
1176 | { | |
1177 | char sni_name[MAX_HOST_LEN]; | |
1178 | size_t data_len = MAX_HOST_LEN; | |
1179 | exim_gnutls_state_st *state = current_global_tls_state; | |
1180 | unsigned int sni_type; | |
1181 | int rc, old_pool; | |
1182 | ||
1183 | rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0); | |
b34fc30c PP |
1184 | if (rc != GNUTLS_E_SUCCESS) |
1185 | { | |
1186 | DEBUG(D_tls) { | |
1187 | if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) | |
1188 | debug_printf("TLS: no SNI presented in handshake.\n"); | |
1189 | else | |
1190 | debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n", | |
1191 | gnutls_strerror(rc), rc); | |
1192 | }; | |
1193 | return 0; | |
1194 | } | |
1195 | ||
17c76198 PP |
1196 | if (sni_type != GNUTLS_NAME_DNS) |
1197 | { | |
1198 | DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type); | |
1199 | return 0; | |
1200 | } | |
44bbabb5 | 1201 | |
17c76198 PP |
1202 | /* We now have a UTF-8 string in sni_name */ |
1203 | old_pool = store_pool; | |
1204 | store_pool = POOL_PERM; | |
1205 | state->received_sni = string_copyn(US sni_name, data_len); | |
1206 | store_pool = old_pool; | |
1207 | ||
1208 | /* We set this one now so that variable expansions below will work */ | |
1209 | tls_sni = state->received_sni; | |
1210 | ||
1211 | DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name, | |
1212 | state->trigger_sni_changes ? "" : " (unused for certificate selection)"); | |
1213 | ||
1214 | if (!state->trigger_sni_changes) | |
1215 | return 0; | |
1216 | ||
1217 | rc = tls_expand_session_files(state); | |
1218 | if (rc != OK) | |
1219 | { | |
1220 | /* If the setup of certs/etc failed before handshake, TLS would not have | |
1221 | been offered. The best we can do now is abort. */ | |
1222 | return GNUTLS_E_APPLICATION_ERROR_MIN; | |
1223 | } | |
1224 | ||
1365611d PP |
1225 | rc = tls_set_remaining_x509(state); |
1226 | if (rc != OK) return GNUTLS_E_APPLICATION_ERROR_MIN; | |
1227 | ||
1228 | return 0; | |
059ec3d9 PH |
1229 | } |
1230 | ||
1231 | ||
1232 | ||
17c76198 PP |
1233 | |
1234 | /* ------------------------------------------------------------------------ */ | |
1235 | /* Exported functions */ | |
1236 | ||
1237 | ||
1238 | ||
1239 | ||
059ec3d9 PH |
1240 | /************************************************* |
1241 | * Start a TLS session in a server * | |
1242 | *************************************************/ | |
1243 | ||
1244 | /* This is called when Exim is running as a server, after having received | |
1245 | the STARTTLS command. It must respond to that command, and then negotiate | |
1246 | a TLS session. | |
1247 | ||
1248 | Arguments: | |
83da1223 | 1249 | require_ciphers list of allowed ciphers or NULL |
059ec3d9 PH |
1250 | |
1251 | Returns: OK on success | |
1252 | DEFER for errors before the start of the negotiation | |
1253 | FAIL for errors during the negotation; the server can't | |
1254 | continue running. | |
1255 | */ | |
1256 | ||
1257 | int | |
17c76198 | 1258 | tls_server_start(const uschar *require_ciphers) |
059ec3d9 PH |
1259 | { |
1260 | int rc; | |
7199e1ee | 1261 | const char *error; |
17c76198 | 1262 | exim_gnutls_state_st *state = NULL; |
059ec3d9 PH |
1263 | |
1264 | /* Check for previous activation */ | |
17c76198 | 1265 | /* nb: this will not be TLS callout safe, needs reworking as part of that. */ |
059ec3d9 PH |
1266 | |
1267 | if (tls_active >= 0) | |
1268 | { | |
17c76198 | 1269 | tls_error(US"STARTTLS received after TLS started", "", NULL); |
059ec3d9 PH |
1270 | smtp_printf("554 Already in TLS\r\n"); |
1271 | return FAIL; | |
1272 | } | |
1273 | ||
1274 | /* Initialize the library. If it fails, it will already have logged the error | |
1275 | and sent an SMTP response. */ | |
1276 | ||
17c76198 | 1277 | DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n"); |
059ec3d9 | 1278 | |
17c76198 PP |
1279 | rc = tls_init(NULL, tls_certificate, tls_privatekey, |
1280 | NULL, tls_verify_certificates, tls_crl, | |
1281 | require_ciphers, &state); | |
059ec3d9 PH |
1282 | if (rc != OK) return rc; |
1283 | ||
059ec3d9 PH |
1284 | /* If this is a host for which certificate verification is mandatory or |
1285 | optional, set up appropriately. */ | |
1286 | ||
059ec3d9 | 1287 | if (verify_check_host(&tls_verify_hosts) == OK) |
17c76198 PP |
1288 | { |
1289 | DEBUG(D_tls) debug_printf("TLS: a client certificate will be required.\n"); | |
1290 | state->verify_requirement = VERIFY_REQUIRED; | |
1291 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE); | |
1292 | } | |
059ec3d9 | 1293 | else if (verify_check_host(&tls_try_verify_hosts) == OK) |
17c76198 PP |
1294 | { |
1295 | DEBUG(D_tls) debug_printf("TLS: a client certificate will be requested but not required.\n"); | |
1296 | state->verify_requirement = VERIFY_OPTIONAL; | |
1297 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST); | |
1298 | } | |
1299 | else | |
1300 | { | |
1301 | DEBUG(D_tls) debug_printf("TLS: a client certificate will not be requested.\n"); | |
1302 | state->verify_requirement = VERIFY_NONE; | |
1303 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE); | |
1304 | } | |
059ec3d9 | 1305 | |
17c76198 PP |
1306 | /* Register SNI handling; always, even if not in tls_certificate, so that the |
1307 | expansion variable $tls_sni is always available. */ | |
059ec3d9 | 1308 | |
17c76198 PP |
1309 | gnutls_handshake_set_post_client_hello_function(state->session, |
1310 | exim_sni_handling_cb); | |
059ec3d9 PH |
1311 | |
1312 | /* Set context and tell client to go ahead, except in the case of TLS startup | |
1313 | on connection, where outputting anything now upsets the clients and tends to | |
1314 | make them disconnect. We need to have an explicit fflush() here, to force out | |
1315 | the response. Other smtp_printf() calls do not need it, because in non-TLS | |
1316 | mode, the fflush() happens when smtp_getc() is called. */ | |
1317 | ||
1318 | if (!tls_on_connect) | |
1319 | { | |
1320 | smtp_printf("220 TLS go ahead\r\n"); | |
1321 | fflush(smtp_out); | |
1322 | } | |
1323 | ||
1324 | /* Now negotiate the TLS session. We put our own timer on it, since it seems | |
1325 | that the GnuTLS library doesn't. */ | |
1326 | ||
17c76198 PP |
1327 | gnutls_transport_set_ptr2(state->session, |
1328 | (gnutls_transport_ptr)fileno(smtp_in), | |
1329 | (gnutls_transport_ptr)fileno(smtp_out)); | |
1330 | state->fd_in = fileno(smtp_in); | |
1331 | state->fd_out = fileno(smtp_out); | |
059ec3d9 PH |
1332 | |
1333 | sigalrm_seen = FALSE; | |
1334 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
17c76198 PP |
1335 | do |
1336 | { | |
1337 | rc = gnutls_handshake(state->session); | |
1338 | } while ((rc == GNUTLS_E_AGAIN) || (rc == GNUTLS_E_INTERRUPTED)); | |
059ec3d9 PH |
1339 | alarm(0); |
1340 | ||
17c76198 | 1341 | if (rc != GNUTLS_E_SUCCESS) |
059ec3d9 | 1342 | { |
17c76198 PP |
1343 | tls_error(US"gnutls_handshake", |
1344 | sigalrm_seen ? "timed out" : gnutls_strerror(rc), NULL); | |
059ec3d9 PH |
1345 | /* It seems that, except in the case of a timeout, we have to close the |
1346 | connection right here; otherwise if the other end is running OpenSSL it hangs | |
1347 | until the server times out. */ | |
1348 | ||
1349 | if (!sigalrm_seen) | |
1350 | { | |
f1e894f3 PH |
1351 | (void)fclose(smtp_out); |
1352 | (void)fclose(smtp_in); | |
059ec3d9 PH |
1353 | } |
1354 | ||
1355 | return FAIL; | |
1356 | } | |
1357 | ||
1358 | DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n"); | |
1359 | ||
17c76198 PP |
1360 | /* Verify after the fact */ |
1361 | ||
1362 | if (state->verify_requirement != VERIFY_NONE) | |
059ec3d9 | 1363 | { |
17c76198 PP |
1364 | if (!verify_certificate(state, &error)) |
1365 | { | |
1366 | if (state->verify_requirement == VERIFY_OPTIONAL) | |
1367 | { | |
1368 | DEBUG(D_tls) | |
1369 | debug_printf("TLS: continuing on only because verification was optional, after: %s\n", | |
1370 | error); | |
1371 | } | |
1372 | else | |
1373 | { | |
1374 | tls_error(US"certificate verification failed", error, NULL); | |
1375 | return FAIL; | |
1376 | } | |
1377 | } | |
059ec3d9 PH |
1378 | } |
1379 | ||
17c76198 PP |
1380 | /* Figure out peer DN, and if authenticated, etc. */ |
1381 | ||
1382 | rc = peer_status(state); | |
1383 | if (rc != OK) return rc; | |
1384 | ||
1385 | /* Sets various Exim expansion variables; always safe within server */ | |
1386 | ||
1387 | extract_exim_vars_from_tls_state(state); | |
059ec3d9 PH |
1388 | |
1389 | /* TLS has been set up. Adjust the input functions to read via TLS, | |
1390 | and initialize appropriately. */ | |
1391 | ||
17c76198 | 1392 | state->xfer_buffer = store_malloc(ssl_xfer_buffer_size); |
059ec3d9 PH |
1393 | |
1394 | receive_getc = tls_getc; | |
1395 | receive_ungetc = tls_ungetc; | |
1396 | receive_feof = tls_feof; | |
1397 | receive_ferror = tls_ferror; | |
58eb016e | 1398 | receive_smtp_buffered = tls_smtp_buffered; |
059ec3d9 | 1399 | |
059ec3d9 PH |
1400 | return OK; |
1401 | } | |
1402 | ||
1403 | ||
1404 | ||
1405 | ||
1406 | /************************************************* | |
1407 | * Start a TLS session in a client * | |
1408 | *************************************************/ | |
1409 | ||
1410 | /* Called from the smtp transport after STARTTLS has been accepted. | |
1411 | ||
1412 | Arguments: | |
1413 | fd the fd of the connection | |
1414 | host connected host (for messages) | |
83da1223 | 1415 | addr the first address (not used) |
17c76198 | 1416 | dhparam DH parameter file (ignored, we're a client) |
059ec3d9 PH |
1417 | certificate certificate file |
1418 | privatekey private key file | |
3f0945ff | 1419 | sni TLS SNI to send to remote host |
059ec3d9 PH |
1420 | verify_certs file for certificate verify |
1421 | verify_crl CRL for verify | |
83da1223 | 1422 | require_ciphers list of allowed ciphers or NULL |
059ec3d9 PH |
1423 | timeout startup timeout |
1424 | ||
1425 | Returns: OK/DEFER/FAIL (because using common functions), | |
1426 | but for a client, DEFER and FAIL have the same meaning | |
1427 | */ | |
1428 | ||
1429 | int | |
17c76198 PP |
1430 | tls_client_start(int fd, host_item *host, |
1431 | address_item *addr ARG_UNUSED, uschar *dhparam ARG_UNUSED, | |
1432 | uschar *certificate, uschar *privatekey, uschar *sni, | |
1433 | uschar *verify_certs, uschar *verify_crl, | |
1434 | uschar *require_ciphers, int timeout) | |
059ec3d9 | 1435 | { |
059ec3d9 | 1436 | int rc; |
17c76198 PP |
1437 | const char *error; |
1438 | exim_gnutls_state_st *state = NULL; | |
059ec3d9 | 1439 | |
17c76198 | 1440 | DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", fd); |
059ec3d9 | 1441 | |
17c76198 PP |
1442 | rc = tls_init(host, certificate, privatekey, |
1443 | sni, verify_certs, verify_crl, require_ciphers, &state); | |
059ec3d9 PH |
1444 | if (rc != OK) return rc; |
1445 | ||
17c76198 | 1446 | gnutls_dh_set_prime_bits(state->session, EXIM_CLIENT_DH_MIN_BITS); |
83da1223 | 1447 | |
17c76198 PP |
1448 | if (verify_certs == NULL) |
1449 | { | |
1450 | DEBUG(D_tls) debug_printf("TLS: server certificate verification not required\n"); | |
1451 | state->verify_requirement = VERIFY_NONE; | |
1452 | /* we still ask for it, to log it, etc */ | |
1453 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST); | |
1454 | } | |
1455 | else | |
1456 | { | |
1457 | DEBUG(D_tls) debug_printf("TLS: server certificate verification required\n"); | |
1458 | state->verify_requirement = VERIFY_REQUIRED; | |
1459 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE); | |
1460 | } | |
059ec3d9 | 1461 | |
17c76198 PP |
1462 | gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr)fd); |
1463 | state->fd_in = fd; | |
1464 | state->fd_out = fd; | |
059ec3d9 PH |
1465 | |
1466 | /* There doesn't seem to be a built-in timeout on connection. */ | |
1467 | ||
1468 | sigalrm_seen = FALSE; | |
1469 | alarm(timeout); | |
17c76198 PP |
1470 | do |
1471 | { | |
1472 | rc = gnutls_handshake(state->session); | |
1473 | } while ((rc == GNUTLS_E_AGAIN) || (rc == GNUTLS_E_INTERRUPTED)); | |
059ec3d9 PH |
1474 | alarm(0); |
1475 | ||
17c76198 | 1476 | DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n"); |
059ec3d9 | 1477 | |
17c76198 | 1478 | /* Verify late */ |
059ec3d9 | 1479 | |
17c76198 PP |
1480 | if (state->verify_requirement != VERIFY_NONE && |
1481 | !verify_certificate(state, &error)) | |
1482 | return tls_error(US"certificate verification failed", error, state->host); | |
059ec3d9 | 1483 | |
17c76198 | 1484 | /* Figure out peer DN, and if authenticated, etc. */ |
059ec3d9 | 1485 | |
17c76198 PP |
1486 | rc = peer_status(state); |
1487 | if (rc != OK) return rc; | |
059ec3d9 | 1488 | |
17c76198 | 1489 | /* Sets various Exim expansion variables; always safe within server */ |
059ec3d9 | 1490 | |
17c76198 | 1491 | extract_exim_vars_from_tls_state(state); |
059ec3d9 | 1492 | |
059ec3d9 PH |
1493 | return OK; |
1494 | } | |
1495 | ||
1496 | ||
1497 | ||
17c76198 | 1498 | |
059ec3d9 | 1499 | /************************************************* |
17c76198 | 1500 | * Close down a TLS session * |
059ec3d9 PH |
1501 | *************************************************/ |
1502 | ||
17c76198 PP |
1503 | /* This is also called from within a delivery subprocess forked from the |
1504 | daemon, to shut down the TLS library, without actually doing a shutdown (which | |
1505 | would tamper with the TLS session in the parent process). | |
059ec3d9 | 1506 | |
17c76198 PP |
1507 | Arguments: TRUE if gnutls_bye is to be called |
1508 | Returns: nothing | |
059ec3d9 PH |
1509 | */ |
1510 | ||
17c76198 PP |
1511 | void |
1512 | tls_close(BOOL shutdown) | |
059ec3d9 | 1513 | { |
17c76198 | 1514 | exim_gnutls_state_st *state = current_global_tls_state; |
059ec3d9 | 1515 | |
17c76198 PP |
1516 | if (tls_active < 0) return; /* TLS was not active */ |
1517 | ||
1518 | if (shutdown) | |
1519 | { | |
1520 | DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS\n"); | |
1521 | gnutls_bye(state->session, GNUTLS_SHUT_WR); | |
1522 | } | |
1523 | ||
1524 | gnutls_deinit(state->session); | |
1525 | ||
1526 | memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); | |
1527 | ||
1528 | if ((state_server.session == NULL) && (state_client.session == NULL)) | |
1529 | { | |
1530 | gnutls_global_deinit(); | |
1531 | exim_gnutls_base_init_done = FALSE; | |
1532 | } | |
7199e1ee | 1533 | |
17c76198 | 1534 | tls_active = -1; |
059ec3d9 PH |
1535 | } |
1536 | ||
1537 | ||
1538 | ||
17c76198 | 1539 | |
059ec3d9 PH |
1540 | /************************************************* |
1541 | * TLS version of getc * | |
1542 | *************************************************/ | |
1543 | ||
1544 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, | |
1545 | it refills the buffer via the GnuTLS reading function. | |
1546 | ||
17c76198 PP |
1547 | This feeds DKIM and should be used for all message-body reads. |
1548 | ||
059ec3d9 PH |
1549 | Arguments: none |
1550 | Returns: the next character or EOF | |
1551 | */ | |
1552 | ||
1553 | int | |
1554 | tls_getc(void) | |
1555 | { | |
17c76198 PP |
1556 | exim_gnutls_state_st *state = current_global_tls_state; |
1557 | if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm) | |
059ec3d9 | 1558 | { |
17c76198 | 1559 | ssize_t inbytes; |
059ec3d9 | 1560 | |
17c76198 PP |
1561 | DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%p, %p, %u)\n", |
1562 | state->session, state->xfer_buffer, ssl_xfer_buffer_size); | |
059ec3d9 PH |
1563 | |
1564 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
17c76198 | 1565 | inbytes = gnutls_record_recv(state->session, state->xfer_buffer, |
059ec3d9 PH |
1566 | ssl_xfer_buffer_size); |
1567 | alarm(0); | |
1568 | ||
1569 | /* A zero-byte return appears to mean that the TLS session has been | |
1570 | closed down, not that the socket itself has been closed down. Revert to | |
1571 | non-TLS handling. */ | |
1572 | ||
1573 | if (inbytes == 0) | |
1574 | { | |
1575 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); | |
1576 | ||
1577 | receive_getc = smtp_getc; | |
1578 | receive_ungetc = smtp_ungetc; | |
1579 | receive_feof = smtp_feof; | |
1580 | receive_ferror = smtp_ferror; | |
58eb016e | 1581 | receive_smtp_buffered = smtp_buffered; |
059ec3d9 | 1582 | |
17c76198 PP |
1583 | gnutls_deinit(state->session); |
1584 | state->session = NULL; | |
059ec3d9 | 1585 | tls_active = -1; |
17c76198 PP |
1586 | tls_bits = 0; |
1587 | tls_certificate_verified = FALSE; | |
1588 | tls_channelbinding_b64 = NULL; | |
059ec3d9 PH |
1589 | tls_cipher = NULL; |
1590 | tls_peerdn = NULL; | |
1591 | ||
1592 | return smtp_getc(); | |
1593 | } | |
1594 | ||
1595 | /* Handle genuine errors */ | |
1596 | ||
1597 | else if (inbytes < 0) | |
1598 | { | |
17c76198 PP |
1599 | record_io_error(state, (int) inbytes, US"recv", NULL); |
1600 | state->xfer_error = 1; | |
059ec3d9 PH |
1601 | return EOF; |
1602 | } | |
80a47a2c | 1603 | #ifndef DISABLE_DKIM |
17c76198 | 1604 | dkim_exim_verify_feed(state->xfer_buffer, inbytes); |
80a47a2c | 1605 | #endif |
17c76198 PP |
1606 | state->xfer_buffer_hwm = (int) inbytes; |
1607 | state->xfer_buffer_lwm = 0; | |
059ec3d9 PH |
1608 | } |
1609 | ||
059ec3d9 PH |
1610 | /* Something in the buffer; return next uschar */ |
1611 | ||
17c76198 | 1612 | return state->xfer_buffer[state->xfer_buffer_lwm++]; |
059ec3d9 PH |
1613 | } |
1614 | ||
1615 | ||
1616 | ||
17c76198 | 1617 | |
059ec3d9 PH |
1618 | /************************************************* |
1619 | * Read bytes from TLS channel * | |
1620 | *************************************************/ | |
1621 | ||
17c76198 PP |
1622 | /* This does not feed DKIM, so if the caller uses this for reading message body, |
1623 | then the caller must feed DKIM. | |
059ec3d9 PH |
1624 | Arguments: |
1625 | buff buffer of data | |
1626 | len size of buffer | |
1627 | ||
1628 | Returns: the number of bytes read | |
1629 | -1 after a failed read | |
1630 | */ | |
1631 | ||
1632 | int | |
1633 | tls_read(uschar *buff, size_t len) | |
1634 | { | |
17c76198 PP |
1635 | exim_gnutls_state_st *state = current_global_tls_state; |
1636 | ssize_t inbytes; | |
059ec3d9 | 1637 | |
17c76198 PP |
1638 | if (len > INT_MAX) |
1639 | len = INT_MAX; | |
059ec3d9 | 1640 | |
17c76198 PP |
1641 | if (state->xfer_buffer_lwm < state->xfer_buffer_hwm) |
1642 | DEBUG(D_tls) | |
1643 | debug_printf("*** PROBABLY A BUG *** " \ | |
1644 | "tls_read() called with data in the tls_getc() buffer, %d ignored\n", | |
1645 | state->xfer_buffer_hwm - state->xfer_buffer_lwm); | |
1646 | ||
1647 | DEBUG(D_tls) | |
1648 | debug_printf("Calling gnutls_record_recv(%p, %p, " SIZE_T_FMT ")\n", | |
1649 | state->session, buff, len); | |
1650 | ||
1651 | inbytes = gnutls_record_recv(state->session, buff, len); | |
059ec3d9 PH |
1652 | if (inbytes > 0) return inbytes; |
1653 | if (inbytes == 0) | |
1654 | { | |
1655 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); | |
1656 | } | |
17c76198 | 1657 | else record_io_error(state, (int)inbytes, US"recv", NULL); |
059ec3d9 PH |
1658 | |
1659 | return -1; | |
1660 | } | |
1661 | ||
1662 | ||
1663 | ||
17c76198 | 1664 | |
059ec3d9 PH |
1665 | /************************************************* |
1666 | * Write bytes down TLS channel * | |
1667 | *************************************************/ | |
1668 | ||
1669 | /* | |
1670 | Arguments: | |
1671 | buff buffer of data | |
1672 | len number of bytes | |
1673 | ||
1674 | Returns: the number of bytes after a successful write, | |
1675 | -1 after a failed write | |
1676 | */ | |
1677 | ||
1678 | int | |
1679 | tls_write(const uschar *buff, size_t len) | |
1680 | { | |
17c76198 PP |
1681 | ssize_t outbytes; |
1682 | size_t left = len; | |
1683 | exim_gnutls_state_st *state = current_global_tls_state; | |
059ec3d9 | 1684 | |
17c76198 | 1685 | DEBUG(D_tls) debug_printf("tls_do_write(%p, " SIZE_T_FMT ")\n", buff, left); |
059ec3d9 PH |
1686 | while (left > 0) |
1687 | { | |
17c76198 PP |
1688 | DEBUG(D_tls) debug_printf("gnutls_record_send(SSL, %p, " SIZE_T_FMT ")\n", |
1689 | buff, left); | |
1690 | outbytes = gnutls_record_send(state->session, buff, left); | |
059ec3d9 | 1691 | |
17c76198 | 1692 | DEBUG(D_tls) debug_printf("outbytes=" SSIZE_T_FMT "\n", outbytes); |
059ec3d9 PH |
1693 | if (outbytes < 0) |
1694 | { | |
17c76198 | 1695 | record_io_error(state, outbytes, US"send", NULL); |
059ec3d9 PH |
1696 | return -1; |
1697 | } | |
1698 | if (outbytes == 0) | |
1699 | { | |
17c76198 | 1700 | record_io_error(state, 0, US"send", US"TLS channel closed on write"); |
059ec3d9 PH |
1701 | return -1; |
1702 | } | |
1703 | ||
1704 | left -= outbytes; | |
1705 | buff += outbytes; | |
1706 | } | |
1707 | ||
17c76198 PP |
1708 | if (len > INT_MAX) |
1709 | { | |
1710 | DEBUG(D_tls) | |
1711 | debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT ") than INT_MAX\n", | |
1712 | len); | |
1713 | len = INT_MAX; | |
1714 | } | |
1715 | ||
1716 | return (int) len; | |
059ec3d9 PH |
1717 | } |
1718 | ||
1719 | ||
1720 | ||
17c76198 | 1721 | |
059ec3d9 | 1722 | /************************************************* |
17c76198 | 1723 | * Random number generation * |
059ec3d9 PH |
1724 | *************************************************/ |
1725 | ||
17c76198 PP |
1726 | /* Pseudo-random number generation. The result is not expected to be |
1727 | cryptographically strong but not so weak that someone will shoot themselves | |
1728 | in the foot using it as a nonce in input in some email header scheme or | |
1729 | whatever weirdness they'll twist this into. The result should handle fork() | |
1730 | and avoid repeating sequences. OpenSSL handles that for us. | |
059ec3d9 | 1731 | |
17c76198 PP |
1732 | Arguments: |
1733 | max range maximum | |
1734 | Returns a random number in range [0, max-1] | |
059ec3d9 PH |
1735 | */ |
1736 | ||
af3498d6 | 1737 | #ifdef HAVE_GNUTLS_RND |
17c76198 PP |
1738 | int |
1739 | vaguely_random_number(int max) | |
059ec3d9 | 1740 | { |
17c76198 PP |
1741 | unsigned int r; |
1742 | int i, needed_len; | |
1743 | uschar *p; | |
1744 | uschar smallbuf[sizeof(r)]; | |
1745 | ||
1746 | if (max <= 1) | |
1747 | return 0; | |
1748 | ||
1749 | needed_len = sizeof(r); | |
1750 | /* Don't take 8 times more entropy than needed if int is 8 octets and we were | |
1751 | * asked for a number less than 10. */ | |
1752 | for (r = max, i = 0; r; ++i) | |
1753 | r >>= 1; | |
1754 | i = (i + 7) / 8; | |
1755 | if (i < needed_len) | |
1756 | needed_len = i; | |
1757 | ||
1758 | i = gnutls_rnd(GNUTLS_RND_NONCE, smallbuf, needed_len); | |
1759 | if (i < 0) | |
059ec3d9 | 1760 | { |
17c76198 PP |
1761 | DEBUG(D_all) debug_printf("gnutls_rnd() failed, using fallback.\n"); |
1762 | return vaguely_random_number_fallback(max); | |
1763 | } | |
1764 | r = 0; | |
1765 | for (p = smallbuf; needed_len; --needed_len, ++p) | |
1766 | { | |
1767 | r *= 256; | |
1768 | r += *p; | |
059ec3d9 PH |
1769 | } |
1770 | ||
17c76198 PP |
1771 | /* We don't particularly care about weighted results; if someone wants |
1772 | * smooth distribution and cares enough then they should submit a patch then. */ | |
1773 | return r % max; | |
059ec3d9 | 1774 | } |
af3498d6 PP |
1775 | #else /* HAVE_GNUTLS_RND */ |
1776 | int | |
1777 | vaguely_random_number(int max) | |
1778 | { | |
1779 | return vaguely_random_number_fallback(max); | |
1780 | } | |
1781 | #endif /* HAVE_GNUTLS_RND */ | |
059ec3d9 | 1782 | |
36f12725 NM |
1783 | |
1784 | ||
1785 | ||
1786 | /************************************************* | |
1787 | * Report the library versions. * | |
1788 | *************************************************/ | |
1789 | ||
1790 | /* See a description in tls-openssl.c for an explanation of why this exists. | |
1791 | ||
1792 | Arguments: a FILE* to print the results to | |
1793 | Returns: nothing | |
1794 | */ | |
1795 | ||
1796 | void | |
1797 | tls_version_report(FILE *f) | |
1798 | { | |
754a0503 PP |
1799 | fprintf(f, "Library version: GnuTLS: Compile: %s\n" |
1800 | " Runtime: %s\n", | |
1801 | LIBGNUTLS_VERSION, | |
1802 | gnutls_check_version(NULL)); | |
36f12725 NM |
1803 | } |
1804 | ||
059ec3d9 | 1805 | /* End of tls-gnu.c */ |