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; | |
4fe99a6c | 79 | BOOL have_set_peerdn; |
17c76198 PP |
80 | const struct host_item *host; |
81 | uschar *peerdn; | |
75fe387d | 82 | uschar *ciphersuite; |
17c76198 PP |
83 | uschar *received_sni; |
84 | ||
85 | const uschar *tls_certificate; | |
86 | const uschar *tls_privatekey; | |
87 | const uschar *tls_sni; /* client send only, not received */ | |
88 | const uschar *tls_verify_certificates; | |
89 | const uschar *tls_crl; | |
90 | const uschar *tls_require_ciphers; | |
91 | uschar *exp_tls_certificate; | |
92 | uschar *exp_tls_privatekey; | |
93 | uschar *exp_tls_sni; | |
94 | uschar *exp_tls_verify_certificates; | |
95 | uschar *exp_tls_crl; | |
96 | uschar *exp_tls_require_ciphers; | |
97 | ||
98 | uschar *xfer_buffer; | |
99 | int xfer_buffer_lwm; | |
100 | int xfer_buffer_hwm; | |
101 | int xfer_eof; | |
102 | int xfer_error; | |
17c76198 PP |
103 | } exim_gnutls_state_st; |
104 | ||
105 | static const exim_gnutls_state_st exim_gnutls_state_init = { | |
4fe99a6c | 106 | NULL, NULL, NULL, VERIFY_NONE, -1, -1, FALSE, FALSE, FALSE, |
75fe387d | 107 | NULL, NULL, NULL, NULL, |
17c76198 PP |
108 | NULL, NULL, NULL, NULL, NULL, NULL, |
109 | NULL, NULL, NULL, NULL, NULL, NULL, | |
110 | NULL, 0, 0, 0, 0, | |
17c76198 | 111 | }; |
83da1223 | 112 | |
17c76198 PP |
113 | /* Not only do we have our own APIs which don't pass around state, assuming |
114 | it's held in globals, GnuTLS doesn't appear to let us register callback data | |
115 | for callbacks, or as part of the session, so we have to keep a "this is the | |
116 | context we're currently dealing with" pointer and rely upon being | |
117 | single-threaded to keep from processing data on an inbound TLS connection while | |
118 | talking to another TLS connection for an outbound check. This does mean that | |
119 | there's no way for heart-beats to be responded to, for the duration of the | |
120 | second connection. */ | |
059ec3d9 | 121 | |
17c76198 PP |
122 | static exim_gnutls_state_st state_server, state_client; |
123 | static exim_gnutls_state_st *current_global_tls_state; | |
059ec3d9 | 124 | |
17c76198 PP |
125 | /* dh_params are initialised once within the lifetime of a process using TLS; |
126 | if we used TLS in a long-lived daemon, we'd have to reconsider this. But we | |
127 | don't want to repeat this. */ | |
83da1223 | 128 | |
17c76198 | 129 | static gnutls_dh_params_t dh_server_params = NULL; |
059ec3d9 | 130 | |
17c76198 | 131 | /* No idea how this value was chosen; preserving it. Default is 3600. */ |
059ec3d9 | 132 | |
17c76198 | 133 | static const int ssl_session_timeout = 200; |
059ec3d9 | 134 | |
17c76198 | 135 | static const char * const exim_default_gnutls_priority = "NORMAL"; |
83da1223 | 136 | |
17c76198 | 137 | /* Guard library core initialisation */ |
83da1223 | 138 | |
17c76198 | 139 | static BOOL exim_gnutls_base_init_done = FALSE; |
059ec3d9 | 140 | |
059ec3d9 | 141 | |
17c76198 PP |
142 | /* ------------------------------------------------------------------------ */ |
143 | /* macros */ | |
83da1223 | 144 | |
17c76198 | 145 | #define MAX_HOST_LEN 255 |
83da1223 | 146 | |
17c76198 PP |
147 | /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup |
148 | the library logging; a value less than 0 disables the calls to set up logging | |
149 | callbacks. */ | |
2c17bb02 | 150 | #ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL |
17c76198 | 151 | #define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1 |
2c17bb02 | 152 | #endif |
83da1223 | 153 | |
2c17bb02 | 154 | #ifndef EXIM_CLIENT_DH_MIN_BITS |
17c76198 | 155 | #define EXIM_CLIENT_DH_MIN_BITS 1024 |
2c17bb02 | 156 | #endif |
83da1223 | 157 | |
af3498d6 PP |
158 | /* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we |
159 | can ask for a bit-strength. Without that, we stick to the constant we had | |
160 | before, for now. */ | |
2c17bb02 | 161 | #ifndef EXIM_SERVER_DH_BITS_PRE2_12 |
af3498d6 | 162 | #define EXIM_SERVER_DH_BITS_PRE2_12 1024 |
2c17bb02 | 163 | #endif |
af3498d6 | 164 | |
17c76198 PP |
165 | #define exim_gnutls_err_check(Label) do { \ |
166 | if (rc != GNUTLS_E_SUCCESS) { return tls_error((Label), gnutls_strerror(rc), host); } } while (0) | |
059ec3d9 | 167 | |
17c76198 | 168 | #define expand_check_tlsvar(Varname) expand_check(state->Varname, US #Varname, &state->exp_##Varname) |
83da1223 | 169 | |
17c76198 PP |
170 | #if GNUTLS_VERSION_NUMBER >= 0x020c00 |
171 | #define HAVE_GNUTLS_SESSION_CHANNEL_BINDING | |
af3498d6 PP |
172 | #define HAVE_GNUTLS_SEC_PARAM_CONSTANTS |
173 | #define HAVE_GNUTLS_RND | |
17c76198 | 174 | #endif |
83da1223 | 175 | |
af3498d6 PP |
176 | |
177 | ||
178 | ||
179 | /* ------------------------------------------------------------------------ */ | |
180 | /* Callback declarations */ | |
181 | ||
182 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 | |
183 | static void exim_gnutls_logger_cb(int level, const char *message); | |
184 | #endif | |
185 | ||
186 | static int exim_sni_handling_cb(gnutls_session_t session); | |
187 | ||
188 | ||
189 | ||
190 | ||
17c76198 PP |
191 | /* ------------------------------------------------------------------------ */ |
192 | /* Static functions */ | |
059ec3d9 PH |
193 | |
194 | /************************************************* | |
195 | * Handle TLS error * | |
196 | *************************************************/ | |
197 | ||
198 | /* Called from lots of places when errors occur before actually starting to do | |
199 | the TLS handshake, that is, while the session is still in clear. Always returns | |
200 | DEFER for a server and FAIL for a client so that most calls can use "return | |
201 | tls_error(...)" to do this processing and then give an appropriate return. A | |
202 | single function is used for both server and client, because it is called from | |
203 | some shared functions. | |
204 | ||
205 | Argument: | |
206 | prefix text to include in the logged error | |
7199e1ee TF |
207 | msg additional error string (may be NULL) |
208 | usually obtained from gnutls_strerror() | |
17c76198 PP |
209 | host NULL if setting up a server; |
210 | the connected host if setting up a client | |
059ec3d9 PH |
211 | |
212 | Returns: OK/DEFER/FAIL | |
213 | */ | |
214 | ||
215 | static int | |
17c76198 | 216 | tls_error(const uschar *prefix, const char *msg, const host_item *host) |
059ec3d9 | 217 | { |
17c76198 PP |
218 | if (host) |
219 | { | |
220 | log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s)%s%s", | |
221 | host->name, host->address, prefix, msg ? ": " : "", msg ? msg : ""); | |
222 | return FAIL; | |
223 | } | |
224 | else | |
059ec3d9 | 225 | { |
7199e1ee | 226 | uschar *conn_info = smtp_get_connection_info(); |
17c76198 | 227 | if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) |
7199e1ee TF |
228 | conn_info += 5; |
229 | log_write(0, LOG_MAIN, "TLS error on %s (%s)%s%s", | |
17c76198 | 230 | conn_info, prefix, msg ? ": " : "", msg ? msg : ""); |
059ec3d9 PH |
231 | return DEFER; |
232 | } | |
059ec3d9 PH |
233 | } |
234 | ||
235 | ||
236 | ||
17c76198 | 237 | |
059ec3d9 | 238 | /************************************************* |
17c76198 | 239 | * Deal with logging errors during I/O * |
059ec3d9 PH |
240 | *************************************************/ |
241 | ||
17c76198 | 242 | /* We have to get the identity of the peer from saved data. |
059ec3d9 | 243 | |
17c76198 PP |
244 | Argument: |
245 | state the current GnuTLS exim state container | |
246 | rc the GnuTLS error code, or 0 if it's a local error | |
247 | when text identifying read or write | |
248 | text local error text when ec is 0 | |
059ec3d9 | 249 | |
17c76198 | 250 | Returns: nothing |
059ec3d9 PH |
251 | */ |
252 | ||
17c76198 PP |
253 | static void |
254 | record_io_error(exim_gnutls_state_st *state, int rc, uschar *when, uschar *text) | |
059ec3d9 | 255 | { |
17c76198 | 256 | const char *msg; |
059ec3d9 | 257 | |
17c76198 PP |
258 | if (rc == GNUTLS_E_FATAL_ALERT_RECEIVED) |
259 | msg = CS string_sprintf("%s: %s", US gnutls_strerror(rc), | |
260 | US gnutls_alert_get_name(gnutls_alert_get(state->session))); | |
261 | else | |
262 | msg = gnutls_strerror(rc); | |
059ec3d9 | 263 | |
17c76198 PP |
264 | tls_error(when, msg, state->host); |
265 | } | |
059ec3d9 | 266 | |
059ec3d9 | 267 | |
059ec3d9 | 268 | |
059ec3d9 | 269 | |
17c76198 PP |
270 | /************************************************* |
271 | * Set various Exim expansion vars * | |
272 | *************************************************/ | |
059ec3d9 | 273 | |
17c76198 PP |
274 | /* We set various Exim global variables from the state, once a session has |
275 | been established. With TLS callouts, may need to change this to stack | |
276 | variables, or just re-call it with the server state after client callout | |
277 | has finished. | |
059ec3d9 | 278 | |
17c76198 PP |
279 | Make sure anything set here is inset in tls_getc(). |
280 | ||
281 | Sets: | |
282 | tls_active fd | |
283 | tls_bits strength indicator | |
284 | tls_certificate_verified bool indicator | |
285 | tls_channelbinding_b64 for some SASL mechanisms | |
286 | tls_cipher a string | |
287 | tls_peerdn a string | |
288 | tls_sni a (UTF-8) string | |
289 | Also: | |
290 | current_global_tls_state for API limitations | |
291 | ||
292 | Argument: | |
293 | state the relevant exim_gnutls_state_st * | |
294 | */ | |
295 | ||
296 | static void | |
297 | extract_exim_vars_from_tls_state(exim_gnutls_state_st *state) | |
298 | { | |
17c76198 | 299 | gnutls_cipher_algorithm_t cipher; |
17c76198 PP |
300 | #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING |
301 | int old_pool; | |
302 | int rc; | |
303 | gnutls_datum_t channel; | |
304 | #endif | |
305 | ||
306 | current_global_tls_state = state; | |
307 | ||
308 | tls_active = state->fd_out; | |
309 | ||
310 | cipher = gnutls_cipher_get(state->session); | |
311 | /* returns size in "bytes" */ | |
312 | tls_bits = gnutls_cipher_get_key_size(cipher) * 8; | |
313 | ||
75fe387d | 314 | tls_cipher = state->ciphersuite; |
17c76198 PP |
315 | |
316 | DEBUG(D_tls) debug_printf("cipher: %s\n", tls_cipher); | |
317 | ||
318 | tls_certificate_verified = state->peer_cert_verified; | |
059ec3d9 | 319 | |
17c76198 PP |
320 | /* note that tls_channelbinding_b64 is not saved to the spool file, since it's |
321 | only available for use for authenticators while this TLS session is running. */ | |
322 | ||
323 | tls_channelbinding_b64 = NULL; | |
324 | #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING | |
325 | channel.data = NULL; | |
326 | channel.size = 0; | |
327 | rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel); | |
328 | if (rc) { | |
329 | DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc)); | |
330 | } else { | |
331 | old_pool = store_pool; | |
332 | store_pool = POOL_PERM; | |
333 | tls_channelbinding_b64 = auth_b64encode(channel.data, (int)channel.size); | |
334 | store_pool = old_pool; | |
335 | DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage.\n"); | |
336 | } | |
337 | #endif | |
338 | ||
339 | tls_peerdn = state->peerdn; | |
340 | ||
341 | tls_sni = state->received_sni; | |
059ec3d9 PH |
342 | } |
343 | ||
344 | ||
345 | ||
17c76198 | 346 | |
059ec3d9 | 347 | /************************************************* |
575643cd | 348 | * Setup up DH parameters * |
059ec3d9 PH |
349 | *************************************************/ |
350 | ||
575643cd | 351 | /* Generating the D-H parameters may take a long time. They only need to |
059ec3d9 PH |
352 | be re-generated every so often, depending on security policy. What we do is to |
353 | keep these parameters in a file in the spool directory. If the file does not | |
354 | exist, we generate them. This means that it is easy to cause a regeneration. | |
355 | ||
356 | The new file is written as a temporary file and renamed, so that an incomplete | |
357 | file is never present. If two processes both compute some new parameters, you | |
358 | waste a bit of effort, but it doesn't seem worth messing around with locking to | |
359 | prevent this. | |
360 | ||
361 | Argument: | |
362 | host NULL for server, server for client (for error handling) | |
363 | ||
364 | Returns: OK/DEFER/FAIL | |
365 | */ | |
366 | ||
367 | static int | |
17c76198 | 368 | init_server_dh(void) |
059ec3d9 | 369 | { |
17c76198 PP |
370 | int fd, rc; |
371 | unsigned int dh_bits; | |
b5aea5e1 | 372 | gnutls_datum m; |
17c76198 PP |
373 | uschar filename[PATH_MAX]; |
374 | size_t sz; | |
375 | host_item *host = NULL; /* dummy for macros */ | |
059ec3d9 | 376 | |
17c76198 | 377 | DEBUG(D_tls) debug_printf("Initialising GnuTLS server params.\n"); |
059ec3d9 | 378 | |
17c76198 PP |
379 | rc = gnutls_dh_params_init(&dh_server_params); |
380 | exim_gnutls_err_check(US"gnutls_dh_params_init"); | |
059ec3d9 | 381 | |
af3498d6 PP |
382 | #ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS |
383 | /* If you change this constant, also change dh_param_fn_ext so that we can use a | |
17c76198 PP |
384 | different filename and ensure we have sufficient bits. */ |
385 | dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, GNUTLS_SEC_PARAM_NORMAL); | |
386 | if (!dh_bits) | |
387 | return tls_error(US"gnutls_sec_param_to_pk_bits() failed", NULL, NULL); | |
af3498d6 | 388 | DEBUG(D_tls) |
b34fc30c | 389 | debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits.\n", |
af3498d6 PP |
390 | dh_bits); |
391 | #else | |
392 | dh_bits = EXIM_SERVER_DH_BITS_PRE2_12; | |
393 | DEBUG(D_tls) | |
394 | debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits.\n", | |
395 | dh_bits); | |
396 | #endif | |
059ec3d9 | 397 | |
3375e053 PP |
398 | /* Some clients have hard-coded limits. */ |
399 | if (dh_bits > tls_dh_max_bits) | |
400 | { | |
401 | DEBUG(D_tls) | |
402 | debug_printf("tls_dh_max_bits clamping override, using %d bits instead.\n", | |
403 | tls_dh_max_bits); | |
404 | dh_bits = tls_dh_max_bits; | |
405 | } | |
406 | ||
17c76198 | 407 | if (!string_format(filename, sizeof(filename), |
af3498d6 | 408 | "%s/gnutls-params-%d", spool_directory, dh_bits)) |
17c76198 | 409 | return tls_error(US"overlong filename", NULL, NULL); |
059ec3d9 | 410 | |
b5aea5e1 | 411 | /* Open the cache file for reading and if successful, read it and set up the |
575643cd | 412 | parameters. */ |
059ec3d9 PH |
413 | |
414 | fd = Uopen(filename, O_RDONLY, 0); | |
b5aea5e1 | 415 | if (fd >= 0) |
059ec3d9 | 416 | { |
b5aea5e1 | 417 | struct stat statbuf; |
17c76198 PP |
418 | FILE *fp; |
419 | int saved_errno; | |
420 | ||
421 | if (fstat(fd, &statbuf) < 0) /* EIO */ | |
422 | { | |
423 | saved_errno = errno; | |
424 | (void)close(fd); | |
425 | return tls_error(US"TLS cache stat failed", strerror(saved_errno), NULL); | |
426 | } | |
427 | if (!S_ISREG(statbuf.st_mode)) | |
b5aea5e1 PH |
428 | { |
429 | (void)close(fd); | |
17c76198 PP |
430 | return tls_error(US"TLS cache not a file", NULL, NULL); |
431 | } | |
432 | fp = fdopen(fd, "rb"); | |
433 | if (!fp) | |
434 | { | |
435 | saved_errno = errno; | |
436 | (void)close(fd); | |
437 | return tls_error(US"fdopen(TLS cache stat fd) failed", | |
438 | strerror(saved_errno), NULL); | |
b5aea5e1 | 439 | } |
059ec3d9 | 440 | |
b5aea5e1 PH |
441 | m.size = statbuf.st_size; |
442 | m.data = malloc(m.size); | |
443 | if (m.data == NULL) | |
17c76198 PP |
444 | { |
445 | fclose(fp); | |
446 | return tls_error(US"malloc failed", strerror(errno), NULL); | |
447 | } | |
448 | sz = fread(m.data, m.size, 1, fp); | |
449 | if (!sz) | |
450 | { | |
451 | saved_errno = errno; | |
452 | fclose(fp); | |
453 | free(m.data); | |
454 | return tls_error(US"fread failed", strerror(saved_errno), NULL); | |
455 | } | |
456 | fclose(fp); | |
b5aea5e1 | 457 | |
17c76198 | 458 | rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM); |
b5aea5e1 | 459 | free(m.data); |
17c76198 PP |
460 | exim_gnutls_err_check(US"gnutls_dh_params_import_pkcs3"); |
461 | DEBUG(D_tls) debug_printf("read D-H parameters from file \"%s\"\n", filename); | |
b5aea5e1 PH |
462 | } |
463 | ||
464 | /* If the file does not exist, fall through to compute new data and cache it. | |
465 | If there was any other opening error, it is serious. */ | |
466 | ||
182ad5cf PH |
467 | else if (errno == ENOENT) |
468 | { | |
17c76198 | 469 | rc = -1; |
182ad5cf | 470 | DEBUG(D_tls) |
17c76198 | 471 | debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename); |
182ad5cf PH |
472 | } |
473 | else | |
17c76198 PP |
474 | return tls_error(string_open_failed(errno, "\"%s\" for reading", filename), |
475 | NULL, NULL); | |
b5aea5e1 PH |
476 | |
477 | /* If ret < 0, either the cache file does not exist, or the data it contains | |
478 | is not useful. One particular case of this is when upgrading from an older | |
479 | release of Exim in which the data was stored in a different format. We don't | |
480 | try to be clever and support both formats; we just regenerate new data in this | |
481 | case. */ | |
482 | ||
17c76198 | 483 | if (rc < 0) |
b5aea5e1 | 484 | { |
17c76198 | 485 | uschar *temp_fn; |
201f5254 | 486 | unsigned int dh_bits_gen = dh_bits; |
059ec3d9 | 487 | |
17c76198 PP |
488 | if ((PATH_MAX - Ustrlen(filename)) < 10) |
489 | return tls_error(US"Filename too long to generate replacement", | |
490 | CS filename, NULL); | |
059ec3d9 | 491 | |
17c76198 PP |
492 | temp_fn = string_copy(US "%s.XXXXXXX"); |
493 | fd = mkstemp(CS temp_fn); /* modifies temp_fn */ | |
059ec3d9 | 494 | if (fd < 0) |
17c76198 | 495 | return tls_error(US"Unable to open temp file", strerror(errno), NULL); |
059ec3d9 PH |
496 | (void)fchown(fd, exim_uid, exim_gid); /* Probably not necessary */ |
497 | ||
201f5254 PP |
498 | /* GnuTLS overshoots! |
499 | * If we ask for 2236, we might get 2237 or more. | |
500 | * But there's no way to ask GnuTLS how many bits there really are. | |
501 | * We can ask how many bits were used in a TLS session, but that's it! | |
502 | * The prime itself is hidden behind too much abstraction. | |
503 | * So we ask for less, and proceed on a wing and a prayer. | |
504 | * First attempt, subtracted 3 for 2233 and got 2240. | |
505 | */ | |
506 | if (dh_bits > EXIM_CLIENT_DH_MIN_BITS + 10) | |
507 | { | |
508 | dh_bits_gen = dh_bits - 10; | |
509 | DEBUG(D_tls) | |
510 | debug_printf("being paranoid about DH generation, make it '%d' bits'\n", | |
511 | dh_bits_gen); | |
512 | } | |
513 | ||
514 | DEBUG(D_tls) | |
515 | debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n", | |
516 | dh_bits_gen); | |
517 | rc = gnutls_dh_params_generate2(dh_server_params, dh_bits_gen); | |
17c76198 PP |
518 | exim_gnutls_err_check(US"gnutls_dh_params_generate2"); |
519 | ||
520 | /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time, | |
521 | and I confirmed that a NULL call to get the size first is how the GnuTLS | |
522 | sample apps handle this. */ | |
523 | ||
524 | sz = 0; | |
525 | m.data = NULL; | |
526 | rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM, | |
527 | m.data, &sz); | |
528 | if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER) | |
529 | exim_gnutls_err_check(US"gnutls_dh_params_export_pkcs3(NULL) sizing"); | |
530 | m.size = sz; | |
b5aea5e1 PH |
531 | m.data = malloc(m.size); |
532 | if (m.data == NULL) | |
17c76198 | 533 | return tls_error(US"memory allocation failed", strerror(errno), NULL); |
1f00591e | 534 | /* this will return a size 1 less than the allocation size above */ |
17c76198 | 535 | rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM, |
1f00591e | 536 | m.data, &sz); |
17c76198 PP |
537 | if (rc != GNUTLS_E_SUCCESS) |
538 | { | |
539 | free(m.data); | |
540 | exim_gnutls_err_check(US"gnutls_dh_params_export_pkcs3() real"); | |
541 | } | |
1f00591e | 542 | m.size = sz; /* shrink by 1, probably */ |
059ec3d9 | 543 | |
17c76198 PP |
544 | sz = write_to_fd_buf(fd, m.data, (size_t) m.size); |
545 | if (sz != m.size) | |
546 | { | |
547 | free(m.data); | |
548 | return tls_error(US"TLS cache write D-H params failed", | |
549 | strerror(errno), NULL); | |
550 | } | |
b5aea5e1 | 551 | free(m.data); |
17c76198 PP |
552 | sz = write_to_fd_buf(fd, US"\n", 1); |
553 | if (sz != 1) | |
554 | return tls_error(US"TLS cache write D-H params final newline failed", | |
555 | strerror(errno), NULL); | |
556 | ||
557 | rc = close(fd); | |
558 | if (rc) | |
559 | return tls_error(US"TLS cache write close() failed", | |
560 | strerror(errno), NULL); | |
059ec3d9 | 561 | |
17c76198 PP |
562 | if (Urename(temp_fn, filename) < 0) |
563 | return tls_error(string_sprintf("failed to rename \"%s\" as \"%s\"", | |
564 | temp_fn, filename), strerror(errno), NULL); | |
059ec3d9 | 565 | |
17c76198 | 566 | DEBUG(D_tls) debug_printf("wrote D-H parameters to file \"%s\"\n", filename); |
059ec3d9 PH |
567 | } |
568 | ||
17c76198 | 569 | DEBUG(D_tls) debug_printf("initialized server D-H parameters\n"); |
059ec3d9 PH |
570 | return OK; |
571 | } | |
572 | ||
573 | ||
574 | ||
575 | ||
576 | /************************************************* | |
17c76198 | 577 | * Variables re-expanded post-SNI * |
059ec3d9 PH |
578 | *************************************************/ |
579 | ||
17c76198 PP |
580 | /* Called from both server and client code, via tls_init(), and also from |
581 | the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni". | |
582 | ||
583 | We can tell the two apart by state->received_sni being non-NULL in callback. | |
584 | ||
585 | The callback should not call us unless state->trigger_sni_changes is true, | |
586 | which we are responsible for setting on the first pass through. | |
059ec3d9 PH |
587 | |
588 | Arguments: | |
17c76198 | 589 | state exim_gnutls_state_st * |
059ec3d9 PH |
590 | |
591 | Returns: OK/DEFER/FAIL | |
592 | */ | |
593 | ||
594 | static int | |
17c76198 | 595 | tls_expand_session_files(exim_gnutls_state_st *state) |
059ec3d9 | 596 | { |
1365611d | 597 | struct stat statbuf; |
059ec3d9 | 598 | int rc; |
17c76198 PP |
599 | const host_item *host = state->host; /* macro should be reconsidered? */ |
600 | uschar *saved_tls_certificate = NULL; | |
601 | uschar *saved_tls_privatekey = NULL; | |
602 | uschar *saved_tls_verify_certificates = NULL; | |
603 | uschar *saved_tls_crl = NULL; | |
604 | int cert_count; | |
605 | ||
606 | /* We check for tls_sni *before* expansion. */ | |
607 | if (!state->host) | |
608 | { | |
609 | if (!state->received_sni) | |
610 | { | |
619b2b25 | 611 | if (state->tls_certificate && Ustrstr(state->tls_certificate, US"tls_sni")) |
17c76198 PP |
612 | { |
613 | DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI.\n"); | |
614 | state->trigger_sni_changes = TRUE; | |
615 | } | |
616 | } | |
617 | else | |
618 | { | |
1365611d | 619 | /* useful for debugging */ |
17c76198 PP |
620 | saved_tls_certificate = state->exp_tls_certificate; |
621 | saved_tls_privatekey = state->exp_tls_privatekey; | |
622 | saved_tls_verify_certificates = state->exp_tls_verify_certificates; | |
623 | saved_tls_crl = state->exp_tls_crl; | |
624 | } | |
625 | } | |
059ec3d9 | 626 | |
1365611d PP |
627 | rc = gnutls_certificate_allocate_credentials(&state->x509_cred); |
628 | exim_gnutls_err_check(US"gnutls_certificate_allocate_credentials"); | |
629 | ||
17c76198 PP |
630 | /* remember: expand_check_tlsvar() is expand_check() but fiddling with |
631 | state members, assuming consistent naming; and expand_check() returns | |
632 | false if expansion failed, unless expansion was forced to fail. */ | |
059ec3d9 | 633 | |
17c76198 PP |
634 | /* check if we at least have a certificate, before doing expensive |
635 | D-H generation. */ | |
059ec3d9 | 636 | |
17c76198 PP |
637 | if (!expand_check_tlsvar(tls_certificate)) |
638 | return DEFER; | |
059ec3d9 | 639 | |
17c76198 | 640 | /* certificate is mandatory in server, optional in client */ |
059ec3d9 | 641 | |
17c76198 PP |
642 | if ((state->exp_tls_certificate == NULL) || |
643 | (*state->exp_tls_certificate == '\0')) | |
644 | { | |
645 | if (state->host == NULL) | |
646 | return tls_error(US"no TLS server certificate is specified", NULL, NULL); | |
647 | else | |
648 | DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n"); | |
649 | } | |
059ec3d9 | 650 | |
17c76198 | 651 | if (state->tls_privatekey && !expand_check_tlsvar(tls_privatekey)) |
059ec3d9 PH |
652 | return DEFER; |
653 | ||
17c76198 PP |
654 | /* tls_privatekey is optional, defaulting to same file as certificate */ |
655 | ||
656 | if (state->tls_privatekey == NULL || *state->tls_privatekey == '\0') | |
059ec3d9 | 657 | { |
17c76198 PP |
658 | state->tls_privatekey = state->tls_certificate; |
659 | state->exp_tls_privatekey = state->exp_tls_certificate; | |
059ec3d9 | 660 | } |
c91535f3 | 661 | |
059ec3d9 | 662 | |
17c76198 | 663 | if (state->exp_tls_certificate && *state->exp_tls_certificate) |
059ec3d9 PH |
664 | { |
665 | DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n", | |
17c76198 PP |
666 | state->exp_tls_certificate, state->exp_tls_privatekey); |
667 | ||
668 | if (state->received_sni) | |
de365ded | 669 | { |
17c76198 PP |
670 | if ((Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0) && |
671 | (Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0)) | |
672 | { | |
b34fc30c | 673 | DEBUG(D_tls) debug_printf("TLS SNI: cert and key unchanged\n"); |
17c76198 PP |
674 | } |
675 | else | |
676 | { | |
b34fc30c | 677 | DEBUG(D_tls) debug_printf("TLS SNI: have a changed cert/key pair.\n"); |
17c76198 | 678 | } |
8e669ac1 | 679 | } |
059ec3d9 | 680 | |
1365611d PP |
681 | rc = gnutls_certificate_set_x509_key_file(state->x509_cred, |
682 | CS state->exp_tls_certificate, CS state->exp_tls_privatekey, | |
683 | GNUTLS_X509_FMT_PEM); | |
684 | exim_gnutls_err_check( | |
685 | string_sprintf("cert/key setup: cert=%s key=%s", | |
686 | state->exp_tls_certificate, state->exp_tls_privatekey)); | |
687 | DEBUG(D_tls) debug_printf("TLS: cert/key registered\n"); | |
b34fc30c | 688 | } /* tls_certificate */ |
059ec3d9 PH |
689 | |
690 | /* Set the trusted CAs file if one is provided, and then add the CRL if one is | |
691 | provided. Experiment shows that, if the certificate file is empty, an unhelpful | |
692 | error message is provided. However, if we just refrain from setting anything up | |
693 | in that case, certificate verification fails, which seems to be the correct | |
694 | behaviour. */ | |
695 | ||
17c76198 | 696 | if (state->tls_verify_certificates && *state->tls_verify_certificates) |
059ec3d9 | 697 | { |
17c76198 | 698 | if (!expand_check_tlsvar(tls_verify_certificates)) |
059ec3d9 | 699 | return DEFER; |
17c76198 PP |
700 | if (state->tls_crl && *state->tls_crl) |
701 | if (!expand_check_tlsvar(tls_crl)) | |
702 | return DEFER; | |
059ec3d9 | 703 | |
1365611d PP |
704 | if (!(state->exp_tls_verify_certificates && |
705 | *state->exp_tls_verify_certificates)) | |
b34fc30c PP |
706 | { |
707 | DEBUG(D_tls) | |
1365611d PP |
708 | debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n"); |
709 | /* With no tls_verify_certificates, we ignore tls_crl too */ | |
17c76198 | 710 | return OK; |
b34fc30c | 711 | } |
1365611d | 712 | } |
83e2f8a2 PP |
713 | else |
714 | { | |
715 | DEBUG(D_tls) | |
716 | debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n"); | |
717 | return OK; | |
718 | } | |
17c76198 | 719 | |
1365611d PP |
720 | if (Ustat(state->exp_tls_verify_certificates, &statbuf) < 0) |
721 | { | |
722 | log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s " | |
723 | "(tls_verify_certificates): %s", state->exp_tls_verify_certificates, | |
724 | strerror(errno)); | |
725 | return DEFER; | |
726 | } | |
17c76198 | 727 | |
619b2b25 PP |
728 | /* The test suite passes in /dev/null; we could check for that path explicitly, |
729 | but who knows if someone has some weird FIFO which always dumps some certs, or | |
730 | other weirdness. The thing we really want to check is that it's not a | |
731 | directory, since while OpenSSL supports that, GnuTLS does not. | |
732 | So s/!S_ISREG/S_ISDIR/ and change some messsaging ... */ | |
733 | if (S_ISDIR(statbuf.st_mode)) | |
1365611d PP |
734 | { |
735 | DEBUG(D_tls) | |
619b2b25 PP |
736 | debug_printf("verify certificates path is a dir: \"%s\"\n", |
737 | state->exp_tls_verify_certificates); | |
1365611d | 738 | log_write(0, LOG_MAIN|LOG_PANIC, |
619b2b25 | 739 | "tls_verify_certificates \"%s\" is a directory", |
1365611d PP |
740 | state->exp_tls_verify_certificates); |
741 | return DEFER; | |
742 | } | |
059ec3d9 | 743 | |
1365611d PP |
744 | DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n", |
745 | state->exp_tls_verify_certificates, statbuf.st_size); | |
059ec3d9 | 746 | |
1365611d PP |
747 | if (statbuf.st_size == 0) |
748 | { | |
749 | DEBUG(D_tls) | |
750 | debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n"); | |
751 | return OK; | |
752 | } | |
059ec3d9 | 753 | |
1365611d PP |
754 | cert_count = gnutls_certificate_set_x509_trust_file(state->x509_cred, |
755 | CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM); | |
756 | if (cert_count < 0) | |
757 | { | |
758 | rc = cert_count; | |
759 | exim_gnutls_err_check(US"gnutls_certificate_set_x509_trust_file"); | |
760 | } | |
761 | DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n", cert_count); | |
059ec3d9 | 762 | |
5c8cda3a PP |
763 | if (state->tls_crl && *state->tls_crl && |
764 | state->exp_tls_crl && *state->exp_tls_crl) | |
1365611d | 765 | { |
5c8cda3a PP |
766 | DEBUG(D_tls) debug_printf("loading CRL file = %s\n", state->exp_tls_crl); |
767 | cert_count = gnutls_certificate_set_x509_crl_file(state->x509_cred, | |
768 | CS state->exp_tls_crl, GNUTLS_X509_FMT_PEM); | |
769 | if (cert_count < 0) | |
1365611d | 770 | { |
5c8cda3a | 771 | rc = cert_count; |
1365611d PP |
772 | exim_gnutls_err_check(US"gnutls_certificate_set_x509_crl_file"); |
773 | } | |
5c8cda3a | 774 | DEBUG(D_tls) debug_printf("Processed %d CRLs.\n", cert_count); |
1365611d | 775 | } |
059ec3d9 | 776 | |
059ec3d9 PH |
777 | return OK; |
778 | } | |
779 | ||
780 | ||
781 | ||
782 | ||
1365611d PP |
783 | /************************************************* |
784 | * Set X.509 state variables * | |
785 | *************************************************/ | |
786 | ||
787 | /* In GnuTLS, the registered cert/key are not replaced by a later | |
788 | set of a cert/key, so for SNI support we need a whole new x509_cred | |
789 | structure. Which means various other non-re-expanded pieces of state | |
790 | need to be re-set in the new struct, so the setting logic is pulled | |
791 | out to this. | |
792 | ||
793 | Arguments: | |
794 | state exim_gnutls_state_st * | |
795 | ||
796 | Returns: OK/DEFER/FAIL | |
797 | */ | |
798 | ||
799 | static int | |
800 | tls_set_remaining_x509(exim_gnutls_state_st *state) | |
801 | { | |
802 | int rc; | |
803 | const host_item *host = state->host; /* macro should be reconsidered? */ | |
804 | ||
805 | /* Create D-H parameters, or read them from the cache file. This function does | |
806 | its own SMTP error messaging. This only happens for the server, TLS D-H ignores | |
807 | client-side params. */ | |
808 | ||
809 | if (!state->host) | |
810 | { | |
811 | if (!dh_server_params) | |
812 | { | |
813 | rc = init_server_dh(); | |
814 | if (rc != OK) return rc; | |
815 | } | |
816 | gnutls_certificate_set_dh_params(state->x509_cred, dh_server_params); | |
817 | } | |
818 | ||
819 | /* Link the credentials to the session. */ | |
820 | ||
821 | rc = gnutls_credentials_set(state->session, GNUTLS_CRD_CERTIFICATE, state->x509_cred); | |
822 | exim_gnutls_err_check(US"gnutls_credentials_set"); | |
823 | ||
824 | return OK; | |
825 | } | |
826 | ||
059ec3d9 | 827 | /************************************************* |
17c76198 | 828 | * Initialize for GnuTLS * |
059ec3d9 PH |
829 | *************************************************/ |
830 | ||
17c76198 PP |
831 | /* Called from both server and client code. In the case of a server, errors |
832 | before actual TLS negotiation return DEFER. | |
059ec3d9 PH |
833 | |
834 | Arguments: | |
17c76198 PP |
835 | host connected host, if client; NULL if server |
836 | certificate certificate file | |
837 | privatekey private key file | |
838 | sni TLS SNI to send, sometimes when client; else NULL | |
839 | cas CA certs file | |
840 | crl CRL file | |
841 | require_ciphers tls_require_ciphers setting | |
059ec3d9 | 842 | |
17c76198 | 843 | Returns: OK/DEFER/FAIL |
059ec3d9 PH |
844 | */ |
845 | ||
17c76198 PP |
846 | static int |
847 | tls_init( | |
848 | const host_item *host, | |
849 | const uschar *certificate, | |
850 | const uschar *privatekey, | |
851 | const uschar *sni, | |
852 | const uschar *cas, | |
853 | const uschar *crl, | |
854 | const uschar *require_ciphers, | |
855 | exim_gnutls_state_st **caller_state) | |
059ec3d9 | 856 | { |
17c76198 PP |
857 | exim_gnutls_state_st *state; |
858 | int rc; | |
859 | size_t sz; | |
860 | const char *errpos; | |
861 | uschar *p; | |
862 | BOOL want_default_priorities; | |
863 | ||
864 | if (!exim_gnutls_base_init_done) | |
059ec3d9 | 865 | { |
17c76198 PP |
866 | DEBUG(D_tls) debug_printf("GnuTLS global init required.\n"); |
867 | ||
868 | rc = gnutls_global_init(); | |
869 | exim_gnutls_err_check(US"gnutls_global_init"); | |
870 | ||
871 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 | |
872 | DEBUG(D_tls) | |
059ec3d9 | 873 | { |
17c76198 PP |
874 | gnutls_global_set_log_function(exim_gnutls_logger_cb); |
875 | /* arbitrarily chosen level; bump upto 9 for more */ | |
876 | gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL); | |
059ec3d9 | 877 | } |
17c76198 PP |
878 | #endif |
879 | ||
880 | exim_gnutls_base_init_done = TRUE; | |
059ec3d9 | 881 | } |
059ec3d9 | 882 | |
17c76198 PP |
883 | if (host) |
884 | { | |
885 | state = &state_client; | |
886 | memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); | |
887 | DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n"); | |
888 | rc = gnutls_init(&state->session, GNUTLS_CLIENT); | |
889 | } | |
890 | else | |
891 | { | |
892 | state = &state_server; | |
893 | memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); | |
894 | DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n"); | |
895 | rc = gnutls_init(&state->session, GNUTLS_SERVER); | |
896 | } | |
897 | exim_gnutls_err_check(US"gnutls_init"); | |
059ec3d9 | 898 | |
17c76198 | 899 | state->host = host; |
059ec3d9 | 900 | |
17c76198 PP |
901 | state->tls_certificate = certificate; |
902 | state->tls_privatekey = privatekey; | |
5779e6aa | 903 | state->tls_require_ciphers = require_ciphers; |
17c76198 PP |
904 | state->tls_sni = sni; |
905 | state->tls_verify_certificates = cas; | |
906 | state->tls_crl = crl; | |
059ec3d9 | 907 | |
17c76198 PP |
908 | /* This handles the variables that might get re-expanded after TLS SNI; |
909 | that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */ | |
059ec3d9 | 910 | |
17c76198 PP |
911 | DEBUG(D_tls) |
912 | debug_printf("Expanding various TLS configuration options for session credentials.\n"); | |
913 | rc = tls_expand_session_files(state); | |
914 | if (rc != OK) return rc; | |
059ec3d9 | 915 | |
1365611d PP |
916 | /* These are all other parts of the x509_cred handling, since SNI in GnuTLS |
917 | requires a new structure afterwards. */ | |
83da1223 | 918 | |
1365611d PP |
919 | rc = tls_set_remaining_x509(state); |
920 | if (rc != OK) return rc; | |
83da1223 | 921 | |
17c76198 PP |
922 | /* set SNI in client, only */ |
923 | if (host) | |
924 | { | |
925 | if (!expand_check_tlsvar(tls_sni)) | |
926 | return DEFER; | |
927 | if (state->exp_tls_sni && *state->exp_tls_sni) | |
928 | { | |
929 | DEBUG(D_tls) | |
930 | debug_printf("Setting TLS client SNI to \"%s\"\n", state->exp_tls_sni); | |
931 | sz = Ustrlen(state->exp_tls_sni); | |
932 | rc = gnutls_server_name_set(state->session, | |
933 | GNUTLS_NAME_DNS, state->exp_tls_sni, sz); | |
934 | exim_gnutls_err_check(US"gnutls_server_name_set"); | |
935 | } | |
936 | } | |
937 | else if (state->tls_sni) | |
938 | DEBUG(D_tls) debug_printf("*** PROBABLY A BUG *** " \ | |
939 | "have an SNI set for a client [%s]\n", state->tls_sni); | |
83da1223 | 940 | |
17c76198 PP |
941 | /* This is the priority string support, |
942 | http://www.gnu.org/software/gnutls/manual/html_node/Priority-Strings.html | |
943 | and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols. | |
944 | This was backwards incompatible, but means Exim no longer needs to track | |
945 | all algorithms and provide string forms for them. */ | |
83da1223 | 946 | |
17c76198 | 947 | want_default_priorities = TRUE; |
83da1223 | 948 | |
17c76198 | 949 | if (state->tls_require_ciphers && *state->tls_require_ciphers) |
83da1223 | 950 | { |
17c76198 PP |
951 | if (!expand_check_tlsvar(tls_require_ciphers)) |
952 | return DEFER; | |
953 | if (state->exp_tls_require_ciphers && *state->exp_tls_require_ciphers) | |
83da1223 | 954 | { |
17c76198 PP |
955 | DEBUG(D_tls) debug_printf("GnuTLS session cipher/priority \"%s\"\n", |
956 | state->exp_tls_require_ciphers); | |
957 | ||
958 | rc = gnutls_priority_init(&state->priority_cache, | |
959 | CS state->exp_tls_require_ciphers, &errpos); | |
960 | want_default_priorities = FALSE; | |
961 | p = state->exp_tls_require_ciphers; | |
83da1223 PH |
962 | } |
963 | } | |
17c76198 PP |
964 | if (want_default_priorities) |
965 | { | |
83e2f8a2 PP |
966 | DEBUG(D_tls) |
967 | debug_printf("GnuTLS using default session cipher/priority \"%s\"\n", | |
968 | exim_default_gnutls_priority); | |
17c76198 PP |
969 | rc = gnutls_priority_init(&state->priority_cache, |
970 | exim_default_gnutls_priority, &errpos); | |
971 | p = US exim_default_gnutls_priority; | |
972 | } | |
83da1223 | 973 | |
17c76198 PP |
974 | exim_gnutls_err_check(string_sprintf( |
975 | "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"", | |
976 | p, errpos - CS p, errpos)); | |
977 | ||
978 | rc = gnutls_priority_set(state->session, state->priority_cache); | |
979 | exim_gnutls_err_check(US"gnutls_priority_set"); | |
980 | ||
981 | gnutls_db_set_cache_expiration(state->session, ssl_session_timeout); | |
982 | ||
983 | /* Reduce security in favour of increased compatibility, if the admin | |
984 | decides to make that trade-off. */ | |
985 | if (gnutls_compat_mode) | |
83da1223 | 986 | { |
17c76198 PP |
987 | #if LIBGNUTLS_VERSION_NUMBER >= 0x020104 |
988 | DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n"); | |
989 | gnutls_session_enable_compatibility_mode(state->session); | |
990 | #else | |
991 | DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n"); | |
992 | #endif | |
83da1223 PH |
993 | } |
994 | ||
17c76198 PP |
995 | *caller_state = state; |
996 | /* needs to happen before callbacks during handshake */ | |
997 | current_global_tls_state = state; | |
998 | return OK; | |
83da1223 PH |
999 | } |
1000 | ||
1001 | ||
1002 | ||
1003 | ||
059ec3d9 | 1004 | /************************************************* |
17c76198 | 1005 | * Extract peer information * |
059ec3d9 PH |
1006 | *************************************************/ |
1007 | ||
17c76198 | 1008 | /* Called from both server and client code. |
4fe99a6c PP |
1009 | Only this is allowed to set state->peerdn and state->have_set_peerdn |
1010 | and we use that to detect double-calls. | |
059ec3d9 | 1011 | |
75fe387d PP |
1012 | NOTE: the state blocks last while the TLS connection is up, which is fine |
1013 | for logging in the server side, but for the client side, we log after teardown | |
1014 | in src/deliver.c. While the session is up, we can twist about states and | |
1015 | repoint tls_* globals, but those variables used for logging or other variable | |
1016 | expansion that happens _after_ delivery need to have a longer life-time. | |
1017 | ||
1018 | So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from | |
1019 | doing this more than once per generation of a state context. We set them in | |
1020 | the state context, and repoint tls_* to them. After the state goes away, the | |
1021 | tls_* copies of the pointers remain valid and client delivery logging is happy. | |
1022 | ||
1023 | tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues | |
1024 | don't apply. | |
1025 | ||
059ec3d9 | 1026 | Arguments: |
17c76198 | 1027 | state exim_gnutls_state_st * |
059ec3d9 | 1028 | |
17c76198 | 1029 | Returns: OK/DEFER/FAIL |
059ec3d9 PH |
1030 | */ |
1031 | ||
17c76198 PP |
1032 | static int |
1033 | peer_status(exim_gnutls_state_st *state) | |
059ec3d9 | 1034 | { |
75fe387d | 1035 | uschar cipherbuf[256]; |
17c76198 | 1036 | const gnutls_datum *cert_list; |
75fe387d | 1037 | int old_pool, rc; |
17c76198 | 1038 | unsigned int cert_list_size = 0; |
4fe99a6c PP |
1039 | gnutls_protocol_t protocol; |
1040 | gnutls_cipher_algorithm_t cipher; | |
1041 | gnutls_kx_algorithm_t kx; | |
1042 | gnutls_mac_algorithm_t mac; | |
17c76198 PP |
1043 | gnutls_certificate_type_t ct; |
1044 | gnutls_x509_crt_t crt; | |
4fe99a6c | 1045 | uschar *p, *dn_buf; |
17c76198 | 1046 | size_t sz; |
059ec3d9 | 1047 | |
4fe99a6c | 1048 | if (state->have_set_peerdn) |
17c76198 | 1049 | return OK; |
4fe99a6c | 1050 | state->have_set_peerdn = TRUE; |
059ec3d9 | 1051 | |
4fe99a6c | 1052 | state->peerdn = NULL; |
059ec3d9 | 1053 | |
4fe99a6c PP |
1054 | /* tls_cipher */ |
1055 | cipher = gnutls_cipher_get(state->session); | |
1056 | protocol = gnutls_protocol_get_version(state->session); | |
1057 | mac = gnutls_mac_get(state->session); | |
1058 | kx = gnutls_kx_get(state->session); | |
1059 | ||
75fe387d | 1060 | string_format(cipherbuf, sizeof(cipherbuf), |
4fe99a6c PP |
1061 | "%s:%s:%d", |
1062 | gnutls_protocol_get_name(protocol), | |
1063 | gnutls_cipher_suite_get_name(kx, cipher, mac), | |
1064 | (int) gnutls_cipher_get_key_size(cipher) * 8); | |
1065 | ||
1066 | /* I don't see a way that spaces could occur, in the current GnuTLS | |
1067 | code base, but it was a concern in the old code and perhaps older GnuTLS | |
1068 | releases did return "TLS 1.0"; play it safe, just in case. */ | |
75fe387d | 1069 | for (p = cipherbuf; *p != '\0'; ++p) |
4fe99a6c PP |
1070 | if (isspace(*p)) |
1071 | *p = '-'; | |
75fe387d PP |
1072 | old_pool = store_pool; |
1073 | store_pool = POOL_PERM; | |
1074 | state->ciphersuite = string_copy(cipherbuf); | |
1075 | store_pool = old_pool; | |
1076 | tls_cipher = state->ciphersuite; | |
4fe99a6c PP |
1077 | |
1078 | /* tls_peerdn */ | |
17c76198 | 1079 | cert_list = gnutls_certificate_get_peers(state->session, &cert_list_size); |
83da1223 | 1080 | |
17c76198 PP |
1081 | if (cert_list == NULL || cert_list_size == 0) |
1082 | { | |
17c76198 PP |
1083 | DEBUG(D_tls) debug_printf("TLS: no certificate from peer (%p & %d)\n", |
1084 | cert_list, cert_list_size); | |
1085 | if (state->verify_requirement == VERIFY_REQUIRED) | |
1086 | return tls_error(US"certificate verification failed", | |
1087 | "no certificate received from peer", state->host); | |
1088 | return OK; | |
1089 | } | |
059ec3d9 | 1090 | |
17c76198 PP |
1091 | ct = gnutls_certificate_type_get(state->session); |
1092 | if (ct != GNUTLS_CRT_X509) | |
059ec3d9 | 1093 | { |
17c76198 | 1094 | const char *ctn = gnutls_certificate_type_get_name(ct); |
17c76198 PP |
1095 | DEBUG(D_tls) |
1096 | debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn); | |
1097 | if (state->verify_requirement == VERIFY_REQUIRED) | |
1098 | return tls_error(US"certificate verification not possible, unhandled type", | |
1099 | ctn, state->host); | |
1100 | return OK; | |
83da1223 | 1101 | } |
059ec3d9 | 1102 | |
17c76198 PP |
1103 | #define exim_gnutls_peer_err(Label) do { \ |
1104 | if (rc != GNUTLS_E_SUCCESS) { \ | |
1105 | DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", (Label), gnutls_strerror(rc)); \ | |
1106 | if (state->verify_requirement == VERIFY_REQUIRED) { return tls_error((Label), gnutls_strerror(rc), state->host); } \ | |
1107 | return OK; } } while (0) | |
1108 | ||
1109 | rc = gnutls_x509_crt_init(&crt); | |
1110 | exim_gnutls_peer_err(US"gnutls_x509_crt_init (crt)"); | |
1111 | ||
1112 | rc = gnutls_x509_crt_import(crt, &cert_list[0], GNUTLS_X509_FMT_DER); | |
1113 | exim_gnutls_peer_err(US"failed to import certificate [gnutls_x509_crt_import(cert 0)]"); | |
1114 | sz = 0; | |
1115 | rc = gnutls_x509_crt_get_dn(crt, NULL, &sz); | |
1116 | if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER) | |
83da1223 | 1117 | { |
17c76198 PP |
1118 | exim_gnutls_peer_err(US"getting size for cert DN failed"); |
1119 | return FAIL; /* should not happen */ | |
059ec3d9 | 1120 | } |
17c76198 PP |
1121 | dn_buf = store_get_perm(sz); |
1122 | rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz); | |
1123 | exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]"); | |
1124 | state->peerdn = dn_buf; | |
1125 | ||
1126 | return OK; | |
1127 | #undef exim_gnutls_peer_err | |
1128 | } | |
059ec3d9 | 1129 | |
059ec3d9 | 1130 | |
059ec3d9 | 1131 | |
059ec3d9 | 1132 | |
17c76198 PP |
1133 | /************************************************* |
1134 | * Verify peer certificate * | |
1135 | *************************************************/ | |
059ec3d9 | 1136 | |
17c76198 PP |
1137 | /* Called from both server and client code. |
1138 | *Should* be using a callback registered with | |
1139 | gnutls_certificate_set_verify_function() to fail the handshake if we dislike | |
1140 | the peer information, but that's too new for some OSes. | |
059ec3d9 | 1141 | |
17c76198 PP |
1142 | Arguments: |
1143 | state exim_gnutls_state_st * | |
1144 | error where to put an error message | |
059ec3d9 | 1145 | |
17c76198 PP |
1146 | Returns: |
1147 | FALSE if the session should be rejected | |
1148 | TRUE if the cert is okay or we just don't care | |
1149 | */ | |
059ec3d9 | 1150 | |
17c76198 PP |
1151 | static BOOL |
1152 | verify_certificate(exim_gnutls_state_st *state, const char **error) | |
1153 | { | |
1154 | int rc; | |
1155 | unsigned int verify; | |
1156 | ||
1157 | *error = NULL; | |
1158 | ||
1159 | rc = peer_status(state); | |
1160 | if (rc != OK) | |
e6060e2c | 1161 | { |
17c76198 PP |
1162 | verify = GNUTLS_CERT_INVALID; |
1163 | *error = "not supplied"; | |
1164 | } | |
1165 | else | |
1166 | { | |
1167 | rc = gnutls_certificate_verify_peers2(state->session, &verify); | |
e6060e2c NM |
1168 | } |
1169 | ||
17c76198 PP |
1170 | /* Handle the result of verification. INVALID seems to be set as well |
1171 | as REVOKED, but leave the test for both. */ | |
059ec3d9 | 1172 | |
17c76198 PP |
1173 | if ((rc < 0) || (verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED)) != 0) |
1174 | { | |
1175 | state->peer_cert_verified = FALSE; | |
1176 | if (*error == NULL) | |
1177 | *error = ((verify & GNUTLS_CERT_REVOKED) != 0) ? "revoked" : "invalid"; | |
059ec3d9 | 1178 | |
17c76198 PP |
1179 | DEBUG(D_tls) |
1180 | debug_printf("TLS certificate verification failed (%s): peerdn=%s\n", | |
4fe99a6c | 1181 | *error, state->peerdn ? state->peerdn : US"<unset>"); |
059ec3d9 | 1182 | |
17c76198 PP |
1183 | if (state->verify_requirement == VERIFY_REQUIRED) |
1184 | { | |
1185 | gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE); | |
1186 | return FALSE; | |
1187 | } | |
1188 | DEBUG(D_tls) | |
1189 | debug_printf("TLS verify failure overriden (host in tls_try_verify_hosts)\n"); | |
1190 | } | |
1191 | else | |
1192 | { | |
1193 | state->peer_cert_verified = TRUE; | |
4fe99a6c PP |
1194 | DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=%s\n", |
1195 | state->peerdn ? state->peerdn : US"<unset>"); | |
17c76198 | 1196 | } |
059ec3d9 | 1197 | |
17c76198 | 1198 | tls_peerdn = state->peerdn; |
059ec3d9 | 1199 | |
17c76198 PP |
1200 | return TRUE; |
1201 | } | |
059ec3d9 | 1202 | |
17c76198 PP |
1203 | |
1204 | ||
1205 | ||
1206 | /* ------------------------------------------------------------------------ */ | |
1207 | /* Callbacks */ | |
1208 | ||
1209 | /* Logging function which can be registered with | |
1210 | * gnutls_global_set_log_function() | |
1211 | * gnutls_global_set_log_level() 0..9 | |
1212 | */ | |
af3498d6 | 1213 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 |
059ec3d9 | 1214 | static void |
17c76198 | 1215 | exim_gnutls_logger_cb(int level, const char *message) |
059ec3d9 | 1216 | { |
8c79eebf PP |
1217 | size_t len = strlen(message); |
1218 | if (len < 1) | |
1219 | { | |
1220 | DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level); | |
1221 | return; | |
1222 | } | |
1223 | DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message, | |
1224 | message[len-1] == '\n' ? "" : "\n"); | |
17c76198 | 1225 | } |
af3498d6 | 1226 | #endif |
059ec3d9 | 1227 | |
059ec3d9 | 1228 | |
17c76198 PP |
1229 | /* Called after client hello, should handle SNI work. |
1230 | This will always set tls_sni (state->received_sni) if available, | |
1231 | and may trigger presenting different certificates, | |
1232 | if state->trigger_sni_changes is TRUE. | |
059ec3d9 | 1233 | |
17c76198 PP |
1234 | Should be registered with |
1235 | gnutls_handshake_set_post_client_hello_function() | |
059ec3d9 | 1236 | |
17c76198 PP |
1237 | "This callback must return 0 on success or a gnutls error code to terminate the |
1238 | handshake.". | |
059ec3d9 | 1239 | |
17c76198 PP |
1240 | For inability to get SNI information, we return 0. |
1241 | We only return non-zero if re-setup failed. | |
1242 | */ | |
44bbabb5 | 1243 | |
17c76198 PP |
1244 | static int |
1245 | exim_sni_handling_cb(gnutls_session_t session) | |
1246 | { | |
1247 | char sni_name[MAX_HOST_LEN]; | |
1248 | size_t data_len = MAX_HOST_LEN; | |
1249 | exim_gnutls_state_st *state = current_global_tls_state; | |
1250 | unsigned int sni_type; | |
1251 | int rc, old_pool; | |
1252 | ||
1253 | rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0); | |
b34fc30c PP |
1254 | if (rc != GNUTLS_E_SUCCESS) |
1255 | { | |
1256 | DEBUG(D_tls) { | |
1257 | if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) | |
1258 | debug_printf("TLS: no SNI presented in handshake.\n"); | |
1259 | else | |
1260 | debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n", | |
1261 | gnutls_strerror(rc), rc); | |
1262 | }; | |
1263 | return 0; | |
1264 | } | |
1265 | ||
17c76198 PP |
1266 | if (sni_type != GNUTLS_NAME_DNS) |
1267 | { | |
1268 | DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type); | |
1269 | return 0; | |
1270 | } | |
44bbabb5 | 1271 | |
17c76198 PP |
1272 | /* We now have a UTF-8 string in sni_name */ |
1273 | old_pool = store_pool; | |
1274 | store_pool = POOL_PERM; | |
1275 | state->received_sni = string_copyn(US sni_name, data_len); | |
1276 | store_pool = old_pool; | |
1277 | ||
1278 | /* We set this one now so that variable expansions below will work */ | |
1279 | tls_sni = state->received_sni; | |
1280 | ||
1281 | DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name, | |
1282 | state->trigger_sni_changes ? "" : " (unused for certificate selection)"); | |
1283 | ||
1284 | if (!state->trigger_sni_changes) | |
1285 | return 0; | |
1286 | ||
1287 | rc = tls_expand_session_files(state); | |
1288 | if (rc != OK) | |
1289 | { | |
1290 | /* If the setup of certs/etc failed before handshake, TLS would not have | |
1291 | been offered. The best we can do now is abort. */ | |
1292 | return GNUTLS_E_APPLICATION_ERROR_MIN; | |
1293 | } | |
1294 | ||
1365611d PP |
1295 | rc = tls_set_remaining_x509(state); |
1296 | if (rc != OK) return GNUTLS_E_APPLICATION_ERROR_MIN; | |
1297 | ||
1298 | return 0; | |
059ec3d9 PH |
1299 | } |
1300 | ||
1301 | ||
1302 | ||
17c76198 PP |
1303 | |
1304 | /* ------------------------------------------------------------------------ */ | |
1305 | /* Exported functions */ | |
1306 | ||
1307 | ||
1308 | ||
1309 | ||
059ec3d9 PH |
1310 | /************************************************* |
1311 | * Start a TLS session in a server * | |
1312 | *************************************************/ | |
1313 | ||
1314 | /* This is called when Exim is running as a server, after having received | |
1315 | the STARTTLS command. It must respond to that command, and then negotiate | |
1316 | a TLS session. | |
1317 | ||
1318 | Arguments: | |
83da1223 | 1319 | require_ciphers list of allowed ciphers or NULL |
059ec3d9 PH |
1320 | |
1321 | Returns: OK on success | |
1322 | DEFER for errors before the start of the negotiation | |
1323 | FAIL for errors during the negotation; the server can't | |
1324 | continue running. | |
1325 | */ | |
1326 | ||
1327 | int | |
17c76198 | 1328 | tls_server_start(const uschar *require_ciphers) |
059ec3d9 PH |
1329 | { |
1330 | int rc; | |
7199e1ee | 1331 | const char *error; |
17c76198 | 1332 | exim_gnutls_state_st *state = NULL; |
059ec3d9 PH |
1333 | |
1334 | /* Check for previous activation */ | |
17c76198 | 1335 | /* nb: this will not be TLS callout safe, needs reworking as part of that. */ |
059ec3d9 PH |
1336 | |
1337 | if (tls_active >= 0) | |
1338 | { | |
17c76198 | 1339 | tls_error(US"STARTTLS received after TLS started", "", NULL); |
059ec3d9 PH |
1340 | smtp_printf("554 Already in TLS\r\n"); |
1341 | return FAIL; | |
1342 | } | |
1343 | ||
1344 | /* Initialize the library. If it fails, it will already have logged the error | |
1345 | and sent an SMTP response. */ | |
1346 | ||
17c76198 | 1347 | DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n"); |
059ec3d9 | 1348 | |
17c76198 PP |
1349 | rc = tls_init(NULL, tls_certificate, tls_privatekey, |
1350 | NULL, tls_verify_certificates, tls_crl, | |
1351 | require_ciphers, &state); | |
059ec3d9 PH |
1352 | if (rc != OK) return rc; |
1353 | ||
059ec3d9 PH |
1354 | /* If this is a host for which certificate verification is mandatory or |
1355 | optional, set up appropriately. */ | |
1356 | ||
059ec3d9 | 1357 | if (verify_check_host(&tls_verify_hosts) == OK) |
17c76198 PP |
1358 | { |
1359 | DEBUG(D_tls) debug_printf("TLS: a client certificate will be required.\n"); | |
1360 | state->verify_requirement = VERIFY_REQUIRED; | |
1361 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE); | |
1362 | } | |
059ec3d9 | 1363 | else if (verify_check_host(&tls_try_verify_hosts) == OK) |
17c76198 PP |
1364 | { |
1365 | DEBUG(D_tls) debug_printf("TLS: a client certificate will be requested but not required.\n"); | |
1366 | state->verify_requirement = VERIFY_OPTIONAL; | |
1367 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST); | |
1368 | } | |
1369 | else | |
1370 | { | |
1371 | DEBUG(D_tls) debug_printf("TLS: a client certificate will not be requested.\n"); | |
1372 | state->verify_requirement = VERIFY_NONE; | |
1373 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE); | |
1374 | } | |
059ec3d9 | 1375 | |
17c76198 PP |
1376 | /* Register SNI handling; always, even if not in tls_certificate, so that the |
1377 | expansion variable $tls_sni is always available. */ | |
059ec3d9 | 1378 | |
17c76198 PP |
1379 | gnutls_handshake_set_post_client_hello_function(state->session, |
1380 | exim_sni_handling_cb); | |
059ec3d9 PH |
1381 | |
1382 | /* Set context and tell client to go ahead, except in the case of TLS startup | |
1383 | on connection, where outputting anything now upsets the clients and tends to | |
1384 | make them disconnect. We need to have an explicit fflush() here, to force out | |
1385 | the response. Other smtp_printf() calls do not need it, because in non-TLS | |
1386 | mode, the fflush() happens when smtp_getc() is called. */ | |
1387 | ||
1388 | if (!tls_on_connect) | |
1389 | { | |
1390 | smtp_printf("220 TLS go ahead\r\n"); | |
1391 | fflush(smtp_out); | |
1392 | } | |
1393 | ||
1394 | /* Now negotiate the TLS session. We put our own timer on it, since it seems | |
1395 | that the GnuTLS library doesn't. */ | |
1396 | ||
17c76198 PP |
1397 | gnutls_transport_set_ptr2(state->session, |
1398 | (gnutls_transport_ptr)fileno(smtp_in), | |
1399 | (gnutls_transport_ptr)fileno(smtp_out)); | |
1400 | state->fd_in = fileno(smtp_in); | |
1401 | state->fd_out = fileno(smtp_out); | |
059ec3d9 PH |
1402 | |
1403 | sigalrm_seen = FALSE; | |
1404 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
17c76198 PP |
1405 | do |
1406 | { | |
1407 | rc = gnutls_handshake(state->session); | |
619b2b25 PP |
1408 | } while ((rc == GNUTLS_E_AGAIN) || |
1409 | (rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen)); | |
059ec3d9 PH |
1410 | alarm(0); |
1411 | ||
17c76198 | 1412 | if (rc != GNUTLS_E_SUCCESS) |
059ec3d9 | 1413 | { |
17c76198 PP |
1414 | tls_error(US"gnutls_handshake", |
1415 | sigalrm_seen ? "timed out" : gnutls_strerror(rc), NULL); | |
059ec3d9 PH |
1416 | /* It seems that, except in the case of a timeout, we have to close the |
1417 | connection right here; otherwise if the other end is running OpenSSL it hangs | |
1418 | until the server times out. */ | |
1419 | ||
1420 | if (!sigalrm_seen) | |
1421 | { | |
f1e894f3 PH |
1422 | (void)fclose(smtp_out); |
1423 | (void)fclose(smtp_in); | |
059ec3d9 PH |
1424 | } |
1425 | ||
1426 | return FAIL; | |
1427 | } | |
1428 | ||
1429 | DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n"); | |
1430 | ||
17c76198 PP |
1431 | /* Verify after the fact */ |
1432 | ||
1433 | if (state->verify_requirement != VERIFY_NONE) | |
059ec3d9 | 1434 | { |
17c76198 PP |
1435 | if (!verify_certificate(state, &error)) |
1436 | { | |
1437 | if (state->verify_requirement == VERIFY_OPTIONAL) | |
1438 | { | |
1439 | DEBUG(D_tls) | |
1440 | debug_printf("TLS: continuing on only because verification was optional, after: %s\n", | |
1441 | error); | |
1442 | } | |
1443 | else | |
1444 | { | |
1445 | tls_error(US"certificate verification failed", error, NULL); | |
1446 | return FAIL; | |
1447 | } | |
1448 | } | |
059ec3d9 PH |
1449 | } |
1450 | ||
17c76198 PP |
1451 | /* Figure out peer DN, and if authenticated, etc. */ |
1452 | ||
1453 | rc = peer_status(state); | |
1454 | if (rc != OK) return rc; | |
1455 | ||
1456 | /* Sets various Exim expansion variables; always safe within server */ | |
1457 | ||
1458 | extract_exim_vars_from_tls_state(state); | |
059ec3d9 PH |
1459 | |
1460 | /* TLS has been set up. Adjust the input functions to read via TLS, | |
1461 | and initialize appropriately. */ | |
1462 | ||
17c76198 | 1463 | state->xfer_buffer = store_malloc(ssl_xfer_buffer_size); |
059ec3d9 PH |
1464 | |
1465 | receive_getc = tls_getc; | |
1466 | receive_ungetc = tls_ungetc; | |
1467 | receive_feof = tls_feof; | |
1468 | receive_ferror = tls_ferror; | |
58eb016e | 1469 | receive_smtp_buffered = tls_smtp_buffered; |
059ec3d9 | 1470 | |
059ec3d9 PH |
1471 | return OK; |
1472 | } | |
1473 | ||
1474 | ||
1475 | ||
1476 | ||
1477 | /************************************************* | |
1478 | * Start a TLS session in a client * | |
1479 | *************************************************/ | |
1480 | ||
1481 | /* Called from the smtp transport after STARTTLS has been accepted. | |
1482 | ||
1483 | Arguments: | |
1484 | fd the fd of the connection | |
1485 | host connected host (for messages) | |
83da1223 | 1486 | addr the first address (not used) |
17c76198 | 1487 | dhparam DH parameter file (ignored, we're a client) |
059ec3d9 PH |
1488 | certificate certificate file |
1489 | privatekey private key file | |
3f0945ff | 1490 | sni TLS SNI to send to remote host |
059ec3d9 PH |
1491 | verify_certs file for certificate verify |
1492 | verify_crl CRL for verify | |
83da1223 | 1493 | require_ciphers list of allowed ciphers or NULL |
059ec3d9 PH |
1494 | timeout startup timeout |
1495 | ||
1496 | Returns: OK/DEFER/FAIL (because using common functions), | |
1497 | but for a client, DEFER and FAIL have the same meaning | |
1498 | */ | |
1499 | ||
1500 | int | |
17c76198 PP |
1501 | tls_client_start(int fd, host_item *host, |
1502 | address_item *addr ARG_UNUSED, uschar *dhparam ARG_UNUSED, | |
1503 | uschar *certificate, uschar *privatekey, uschar *sni, | |
1504 | uschar *verify_certs, uschar *verify_crl, | |
1505 | uschar *require_ciphers, int timeout) | |
059ec3d9 | 1506 | { |
059ec3d9 | 1507 | int rc; |
17c76198 PP |
1508 | const char *error; |
1509 | exim_gnutls_state_st *state = NULL; | |
059ec3d9 | 1510 | |
17c76198 | 1511 | DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", fd); |
059ec3d9 | 1512 | |
17c76198 PP |
1513 | rc = tls_init(host, certificate, privatekey, |
1514 | sni, verify_certs, verify_crl, require_ciphers, &state); | |
059ec3d9 PH |
1515 | if (rc != OK) return rc; |
1516 | ||
17c76198 | 1517 | gnutls_dh_set_prime_bits(state->session, EXIM_CLIENT_DH_MIN_BITS); |
83da1223 | 1518 | |
17c76198 PP |
1519 | if (verify_certs == NULL) |
1520 | { | |
1521 | DEBUG(D_tls) debug_printf("TLS: server certificate verification not required\n"); | |
1522 | state->verify_requirement = VERIFY_NONE; | |
1523 | /* we still ask for it, to log it, etc */ | |
1524 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST); | |
1525 | } | |
1526 | else | |
1527 | { | |
1528 | DEBUG(D_tls) debug_printf("TLS: server certificate verification required\n"); | |
1529 | state->verify_requirement = VERIFY_REQUIRED; | |
1530 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE); | |
1531 | } | |
059ec3d9 | 1532 | |
17c76198 PP |
1533 | gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr)fd); |
1534 | state->fd_in = fd; | |
1535 | state->fd_out = fd; | |
059ec3d9 PH |
1536 | |
1537 | /* There doesn't seem to be a built-in timeout on connection. */ | |
1538 | ||
1539 | sigalrm_seen = FALSE; | |
1540 | alarm(timeout); | |
17c76198 PP |
1541 | do |
1542 | { | |
1543 | rc = gnutls_handshake(state->session); | |
619b2b25 PP |
1544 | } while ((rc == GNUTLS_E_AGAIN) || |
1545 | (rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen)); | |
059ec3d9 PH |
1546 | alarm(0); |
1547 | ||
4fe99a6c PP |
1548 | if (rc != GNUTLS_E_SUCCESS) |
1549 | return tls_error(US"gnutls_handshake", | |
1550 | sigalrm_seen ? "timed out" : gnutls_strerror(rc), state->host); | |
1551 | ||
17c76198 | 1552 | DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n"); |
059ec3d9 | 1553 | |
17c76198 | 1554 | /* Verify late */ |
059ec3d9 | 1555 | |
17c76198 PP |
1556 | if (state->verify_requirement != VERIFY_NONE && |
1557 | !verify_certificate(state, &error)) | |
1558 | return tls_error(US"certificate verification failed", error, state->host); | |
059ec3d9 | 1559 | |
17c76198 | 1560 | /* Figure out peer DN, and if authenticated, etc. */ |
059ec3d9 | 1561 | |
17c76198 PP |
1562 | rc = peer_status(state); |
1563 | if (rc != OK) return rc; | |
059ec3d9 | 1564 | |
4fe99a6c | 1565 | /* Sets various Exim expansion variables; may need to adjust for ACL callouts */ |
059ec3d9 | 1566 | |
17c76198 | 1567 | extract_exim_vars_from_tls_state(state); |
059ec3d9 | 1568 | |
059ec3d9 PH |
1569 | return OK; |
1570 | } | |
1571 | ||
1572 | ||
1573 | ||
17c76198 | 1574 | |
059ec3d9 | 1575 | /************************************************* |
17c76198 | 1576 | * Close down a TLS session * |
059ec3d9 PH |
1577 | *************************************************/ |
1578 | ||
17c76198 PP |
1579 | /* This is also called from within a delivery subprocess forked from the |
1580 | daemon, to shut down the TLS library, without actually doing a shutdown (which | |
1581 | would tamper with the TLS session in the parent process). | |
059ec3d9 | 1582 | |
17c76198 PP |
1583 | Arguments: TRUE if gnutls_bye is to be called |
1584 | Returns: nothing | |
059ec3d9 PH |
1585 | */ |
1586 | ||
17c76198 PP |
1587 | void |
1588 | tls_close(BOOL shutdown) | |
059ec3d9 | 1589 | { |
17c76198 | 1590 | exim_gnutls_state_st *state = current_global_tls_state; |
059ec3d9 | 1591 | |
17c76198 PP |
1592 | if (tls_active < 0) return; /* TLS was not active */ |
1593 | ||
1594 | if (shutdown) | |
1595 | { | |
1596 | DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS\n"); | |
1597 | gnutls_bye(state->session, GNUTLS_SHUT_WR); | |
1598 | } | |
1599 | ||
1600 | gnutls_deinit(state->session); | |
1601 | ||
1602 | memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); | |
1603 | ||
1604 | if ((state_server.session == NULL) && (state_client.session == NULL)) | |
1605 | { | |
1606 | gnutls_global_deinit(); | |
1607 | exim_gnutls_base_init_done = FALSE; | |
1608 | } | |
7199e1ee | 1609 | |
17c76198 | 1610 | tls_active = -1; |
059ec3d9 PH |
1611 | } |
1612 | ||
1613 | ||
1614 | ||
17c76198 | 1615 | |
059ec3d9 PH |
1616 | /************************************************* |
1617 | * TLS version of getc * | |
1618 | *************************************************/ | |
1619 | ||
1620 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, | |
1621 | it refills the buffer via the GnuTLS reading function. | |
1622 | ||
17c76198 PP |
1623 | This feeds DKIM and should be used for all message-body reads. |
1624 | ||
059ec3d9 PH |
1625 | Arguments: none |
1626 | Returns: the next character or EOF | |
1627 | */ | |
1628 | ||
1629 | int | |
1630 | tls_getc(void) | |
1631 | { | |
17c76198 PP |
1632 | exim_gnutls_state_st *state = current_global_tls_state; |
1633 | if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm) | |
059ec3d9 | 1634 | { |
17c76198 | 1635 | ssize_t inbytes; |
059ec3d9 | 1636 | |
17c76198 PP |
1637 | DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%p, %p, %u)\n", |
1638 | state->session, state->xfer_buffer, ssl_xfer_buffer_size); | |
059ec3d9 PH |
1639 | |
1640 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
17c76198 | 1641 | inbytes = gnutls_record_recv(state->session, state->xfer_buffer, |
059ec3d9 PH |
1642 | ssl_xfer_buffer_size); |
1643 | alarm(0); | |
1644 | ||
1645 | /* A zero-byte return appears to mean that the TLS session has been | |
1646 | closed down, not that the socket itself has been closed down. Revert to | |
1647 | non-TLS handling. */ | |
1648 | ||
1649 | if (inbytes == 0) | |
1650 | { | |
1651 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); | |
1652 | ||
1653 | receive_getc = smtp_getc; | |
1654 | receive_ungetc = smtp_ungetc; | |
1655 | receive_feof = smtp_feof; | |
1656 | receive_ferror = smtp_ferror; | |
58eb016e | 1657 | receive_smtp_buffered = smtp_buffered; |
059ec3d9 | 1658 | |
17c76198 PP |
1659 | gnutls_deinit(state->session); |
1660 | state->session = NULL; | |
059ec3d9 | 1661 | tls_active = -1; |
17c76198 PP |
1662 | tls_bits = 0; |
1663 | tls_certificate_verified = FALSE; | |
1664 | tls_channelbinding_b64 = NULL; | |
059ec3d9 PH |
1665 | tls_cipher = NULL; |
1666 | tls_peerdn = NULL; | |
1667 | ||
1668 | return smtp_getc(); | |
1669 | } | |
1670 | ||
1671 | /* Handle genuine errors */ | |
1672 | ||
1673 | else if (inbytes < 0) | |
1674 | { | |
17c76198 PP |
1675 | record_io_error(state, (int) inbytes, US"recv", NULL); |
1676 | state->xfer_error = 1; | |
059ec3d9 PH |
1677 | return EOF; |
1678 | } | |
80a47a2c | 1679 | #ifndef DISABLE_DKIM |
17c76198 | 1680 | dkim_exim_verify_feed(state->xfer_buffer, inbytes); |
80a47a2c | 1681 | #endif |
17c76198 PP |
1682 | state->xfer_buffer_hwm = (int) inbytes; |
1683 | state->xfer_buffer_lwm = 0; | |
059ec3d9 PH |
1684 | } |
1685 | ||
059ec3d9 PH |
1686 | /* Something in the buffer; return next uschar */ |
1687 | ||
17c76198 | 1688 | return state->xfer_buffer[state->xfer_buffer_lwm++]; |
059ec3d9 PH |
1689 | } |
1690 | ||
1691 | ||
1692 | ||
17c76198 | 1693 | |
059ec3d9 PH |
1694 | /************************************************* |
1695 | * Read bytes from TLS channel * | |
1696 | *************************************************/ | |
1697 | ||
17c76198 PP |
1698 | /* This does not feed DKIM, so if the caller uses this for reading message body, |
1699 | then the caller must feed DKIM. | |
059ec3d9 PH |
1700 | Arguments: |
1701 | buff buffer of data | |
1702 | len size of buffer | |
1703 | ||
1704 | Returns: the number of bytes read | |
1705 | -1 after a failed read | |
1706 | */ | |
1707 | ||
1708 | int | |
1709 | tls_read(uschar *buff, size_t len) | |
1710 | { | |
17c76198 PP |
1711 | exim_gnutls_state_st *state = current_global_tls_state; |
1712 | ssize_t inbytes; | |
059ec3d9 | 1713 | |
17c76198 PP |
1714 | if (len > INT_MAX) |
1715 | len = INT_MAX; | |
059ec3d9 | 1716 | |
17c76198 PP |
1717 | if (state->xfer_buffer_lwm < state->xfer_buffer_hwm) |
1718 | DEBUG(D_tls) | |
1719 | debug_printf("*** PROBABLY A BUG *** " \ | |
1720 | "tls_read() called with data in the tls_getc() buffer, %d ignored\n", | |
1721 | state->xfer_buffer_hwm - state->xfer_buffer_lwm); | |
1722 | ||
1723 | DEBUG(D_tls) | |
1724 | debug_printf("Calling gnutls_record_recv(%p, %p, " SIZE_T_FMT ")\n", | |
1725 | state->session, buff, len); | |
1726 | ||
1727 | inbytes = gnutls_record_recv(state->session, buff, len); | |
059ec3d9 PH |
1728 | if (inbytes > 0) return inbytes; |
1729 | if (inbytes == 0) | |
1730 | { | |
1731 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); | |
1732 | } | |
17c76198 | 1733 | else record_io_error(state, (int)inbytes, US"recv", NULL); |
059ec3d9 PH |
1734 | |
1735 | return -1; | |
1736 | } | |
1737 | ||
1738 | ||
1739 | ||
17c76198 | 1740 | |
059ec3d9 PH |
1741 | /************************************************* |
1742 | * Write bytes down TLS channel * | |
1743 | *************************************************/ | |
1744 | ||
1745 | /* | |
1746 | Arguments: | |
1747 | buff buffer of data | |
1748 | len number of bytes | |
1749 | ||
1750 | Returns: the number of bytes after a successful write, | |
1751 | -1 after a failed write | |
1752 | */ | |
1753 | ||
1754 | int | |
1755 | tls_write(const uschar *buff, size_t len) | |
1756 | { | |
17c76198 PP |
1757 | ssize_t outbytes; |
1758 | size_t left = len; | |
1759 | exim_gnutls_state_st *state = current_global_tls_state; | |
059ec3d9 | 1760 | |
17c76198 | 1761 | DEBUG(D_tls) debug_printf("tls_do_write(%p, " SIZE_T_FMT ")\n", buff, left); |
059ec3d9 PH |
1762 | while (left > 0) |
1763 | { | |
17c76198 PP |
1764 | DEBUG(D_tls) debug_printf("gnutls_record_send(SSL, %p, " SIZE_T_FMT ")\n", |
1765 | buff, left); | |
1766 | outbytes = gnutls_record_send(state->session, buff, left); | |
059ec3d9 | 1767 | |
17c76198 | 1768 | DEBUG(D_tls) debug_printf("outbytes=" SSIZE_T_FMT "\n", outbytes); |
059ec3d9 PH |
1769 | if (outbytes < 0) |
1770 | { | |
17c76198 | 1771 | record_io_error(state, outbytes, US"send", NULL); |
059ec3d9 PH |
1772 | return -1; |
1773 | } | |
1774 | if (outbytes == 0) | |
1775 | { | |
17c76198 | 1776 | record_io_error(state, 0, US"send", US"TLS channel closed on write"); |
059ec3d9 PH |
1777 | return -1; |
1778 | } | |
1779 | ||
1780 | left -= outbytes; | |
1781 | buff += outbytes; | |
1782 | } | |
1783 | ||
17c76198 PP |
1784 | if (len > INT_MAX) |
1785 | { | |
1786 | DEBUG(D_tls) | |
1787 | debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT ") than INT_MAX\n", | |
1788 | len); | |
1789 | len = INT_MAX; | |
1790 | } | |
1791 | ||
1792 | return (int) len; | |
059ec3d9 PH |
1793 | } |
1794 | ||
1795 | ||
1796 | ||
17c76198 | 1797 | |
059ec3d9 | 1798 | /************************************************* |
17c76198 | 1799 | * Random number generation * |
059ec3d9 PH |
1800 | *************************************************/ |
1801 | ||
17c76198 PP |
1802 | /* Pseudo-random number generation. The result is not expected to be |
1803 | cryptographically strong but not so weak that someone will shoot themselves | |
1804 | in the foot using it as a nonce in input in some email header scheme or | |
1805 | whatever weirdness they'll twist this into. The result should handle fork() | |
1806 | and avoid repeating sequences. OpenSSL handles that for us. | |
059ec3d9 | 1807 | |
17c76198 PP |
1808 | Arguments: |
1809 | max range maximum | |
1810 | Returns a random number in range [0, max-1] | |
059ec3d9 PH |
1811 | */ |
1812 | ||
af3498d6 | 1813 | #ifdef HAVE_GNUTLS_RND |
17c76198 PP |
1814 | int |
1815 | vaguely_random_number(int max) | |
059ec3d9 | 1816 | { |
17c76198 PP |
1817 | unsigned int r; |
1818 | int i, needed_len; | |
1819 | uschar *p; | |
1820 | uschar smallbuf[sizeof(r)]; | |
1821 | ||
1822 | if (max <= 1) | |
1823 | return 0; | |
1824 | ||
1825 | needed_len = sizeof(r); | |
1826 | /* Don't take 8 times more entropy than needed if int is 8 octets and we were | |
1827 | * asked for a number less than 10. */ | |
1828 | for (r = max, i = 0; r; ++i) | |
1829 | r >>= 1; | |
1830 | i = (i + 7) / 8; | |
1831 | if (i < needed_len) | |
1832 | needed_len = i; | |
1833 | ||
1834 | i = gnutls_rnd(GNUTLS_RND_NONCE, smallbuf, needed_len); | |
1835 | if (i < 0) | |
059ec3d9 | 1836 | { |
17c76198 PP |
1837 | DEBUG(D_all) debug_printf("gnutls_rnd() failed, using fallback.\n"); |
1838 | return vaguely_random_number_fallback(max); | |
1839 | } | |
1840 | r = 0; | |
1841 | for (p = smallbuf; needed_len; --needed_len, ++p) | |
1842 | { | |
1843 | r *= 256; | |
1844 | r += *p; | |
059ec3d9 PH |
1845 | } |
1846 | ||
17c76198 PP |
1847 | /* We don't particularly care about weighted results; if someone wants |
1848 | * smooth distribution and cares enough then they should submit a patch then. */ | |
1849 | return r % max; | |
059ec3d9 | 1850 | } |
af3498d6 PP |
1851 | #else /* HAVE_GNUTLS_RND */ |
1852 | int | |
1853 | vaguely_random_number(int max) | |
1854 | { | |
1855 | return vaguely_random_number_fallback(max); | |
1856 | } | |
1857 | #endif /* HAVE_GNUTLS_RND */ | |
059ec3d9 | 1858 | |
36f12725 NM |
1859 | |
1860 | ||
1861 | ||
3375e053 PP |
1862 | /************************************************* |
1863 | * Let tls_require_ciphers be checked at startup * | |
1864 | *************************************************/ | |
1865 | ||
1866 | /* The tls_require_ciphers option, if set, must be something which the | |
1867 | library can parse. | |
1868 | ||
1869 | Returns: NULL on success, or error message | |
1870 | */ | |
1871 | ||
1872 | uschar * | |
1873 | tls_validate_require_cipher(void) | |
1874 | { | |
1875 | int rc; | |
1876 | uschar *expciphers = NULL; | |
1877 | gnutls_priority_t priority_cache; | |
1878 | const char *errpos; | |
1879 | ||
1880 | #define validate_check_rc(Label) do { \ | |
1881 | if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \ | |
1882 | return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0) | |
1883 | #define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0) | |
1884 | ||
1885 | if (exim_gnutls_base_init_done) | |
1886 | log_write(0, LOG_MAIN|LOG_PANIC, | |
1887 | "already initialised GnuTLS, Exim developer bug"); | |
1888 | ||
1889 | rc = gnutls_global_init(); | |
1890 | validate_check_rc(US"gnutls_global_init()"); | |
1891 | exim_gnutls_base_init_done = TRUE; | |
1892 | ||
1893 | if (!(tls_require_ciphers && *tls_require_ciphers)) | |
1894 | return_deinit(NULL); | |
1895 | ||
1896 | if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers)) | |
1897 | return_deinit(US"failed to expand tls_require_ciphers"); | |
1898 | ||
1899 | if (!(expciphers && *expciphers)) | |
1900 | return_deinit(NULL); | |
1901 | ||
1902 | DEBUG(D_tls) | |
1903 | debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers); | |
1904 | ||
1905 | rc = gnutls_priority_init(&priority_cache, CS expciphers, &errpos); | |
1906 | validate_check_rc(string_sprintf( | |
1907 | "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"", | |
1908 | expciphers, errpos - CS expciphers, errpos)); | |
1909 | ||
1910 | #undef return_deinit | |
1911 | #undef validate_check_rc | |
1912 | gnutls_global_deinit(); | |
1913 | ||
1914 | return NULL; | |
1915 | } | |
1916 | ||
1917 | ||
1918 | ||
1919 | ||
36f12725 NM |
1920 | /************************************************* |
1921 | * Report the library versions. * | |
1922 | *************************************************/ | |
1923 | ||
1924 | /* See a description in tls-openssl.c for an explanation of why this exists. | |
1925 | ||
1926 | Arguments: a FILE* to print the results to | |
1927 | Returns: nothing | |
1928 | */ | |
1929 | ||
1930 | void | |
1931 | tls_version_report(FILE *f) | |
1932 | { | |
754a0503 PP |
1933 | fprintf(f, "Library version: GnuTLS: Compile: %s\n" |
1934 | " Runtime: %s\n", | |
1935 | LIBGNUTLS_VERSION, | |
1936 | gnutls_check_version(NULL)); | |
36f12725 NM |
1937 | } |
1938 | ||
059ec3d9 | 1939 | /* End of tls-gnu.c */ |