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 | /* Callback declarations */ | |
059ec3d9 | 145 | |
17c76198 PP |
146 | static void exim_gnutls_logger_cb(int level, const char *message); |
147 | static int exim_sni_handling_cb(gnutls_session_t session); | |
83da1223 | 148 | |
17c76198 PP |
149 | /* ------------------------------------------------------------------------ */ |
150 | /* macros */ | |
83da1223 | 151 | |
17c76198 | 152 | #define MAX_HOST_LEN 255 |
83da1223 | 153 | |
17c76198 PP |
154 | /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup |
155 | the library logging; a value less than 0 disables the calls to set up logging | |
156 | callbacks. */ | |
157 | #define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1 | |
83da1223 | 158 | |
17c76198 | 159 | #define EXIM_CLIENT_DH_MIN_BITS 1024 |
83da1223 | 160 | |
17c76198 PP |
161 | #define exim_gnutls_err_check(Label) do { \ |
162 | if (rc != GNUTLS_E_SUCCESS) { return tls_error((Label), gnutls_strerror(rc), host); } } while (0) | |
059ec3d9 | 163 | |
17c76198 PP |
164 | #define exim_gnutls_err_debugreturn0(Label) do { \ |
165 | if (rc != GNUTLS_E_SUCCESS) { \ | |
166 | DEBUG(D_tls) debug_printf("TLS failure: %s: %s", (Label), gnutls_strerror(rc)); \ | |
167 | return 0; } } while (0) | |
059ec3d9 | 168 | |
17c76198 | 169 | #define expand_check_tlsvar(Varname) expand_check(state->Varname, US #Varname, &state->exp_##Varname) |
83da1223 | 170 | |
17c76198 PP |
171 | #if GNUTLS_VERSION_NUMBER >= 0x020c00 |
172 | #define HAVE_GNUTLS_SESSION_CHANNEL_BINDING | |
173 | #endif | |
83da1223 | 174 | |
17c76198 PP |
175 | /* ------------------------------------------------------------------------ */ |
176 | /* Static functions */ | |
059ec3d9 PH |
177 | |
178 | /************************************************* | |
179 | * Handle TLS error * | |
180 | *************************************************/ | |
181 | ||
182 | /* Called from lots of places when errors occur before actually starting to do | |
183 | the TLS handshake, that is, while the session is still in clear. Always returns | |
184 | DEFER for a server and FAIL for a client so that most calls can use "return | |
185 | tls_error(...)" to do this processing and then give an appropriate return. A | |
186 | single function is used for both server and client, because it is called from | |
187 | some shared functions. | |
188 | ||
189 | Argument: | |
190 | prefix text to include in the logged error | |
7199e1ee TF |
191 | msg additional error string (may be NULL) |
192 | usually obtained from gnutls_strerror() | |
17c76198 PP |
193 | host NULL if setting up a server; |
194 | the connected host if setting up a client | |
059ec3d9 PH |
195 | |
196 | Returns: OK/DEFER/FAIL | |
197 | */ | |
198 | ||
199 | static int | |
17c76198 | 200 | tls_error(const uschar *prefix, const char *msg, const host_item *host) |
059ec3d9 | 201 | { |
17c76198 PP |
202 | if (host) |
203 | { | |
204 | log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s)%s%s", | |
205 | host->name, host->address, prefix, msg ? ": " : "", msg ? msg : ""); | |
206 | return FAIL; | |
207 | } | |
208 | else | |
059ec3d9 | 209 | { |
7199e1ee | 210 | uschar *conn_info = smtp_get_connection_info(); |
17c76198 | 211 | if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) |
7199e1ee TF |
212 | conn_info += 5; |
213 | log_write(0, LOG_MAIN, "TLS error on %s (%s)%s%s", | |
17c76198 | 214 | conn_info, prefix, msg ? ": " : "", msg ? msg : ""); |
059ec3d9 PH |
215 | return DEFER; |
216 | } | |
059ec3d9 PH |
217 | } |
218 | ||
219 | ||
220 | ||
17c76198 | 221 | |
059ec3d9 | 222 | /************************************************* |
17c76198 | 223 | * Deal with logging errors during I/O * |
059ec3d9 PH |
224 | *************************************************/ |
225 | ||
17c76198 | 226 | /* We have to get the identity of the peer from saved data. |
059ec3d9 | 227 | |
17c76198 PP |
228 | Argument: |
229 | state the current GnuTLS exim state container | |
230 | rc the GnuTLS error code, or 0 if it's a local error | |
231 | when text identifying read or write | |
232 | text local error text when ec is 0 | |
059ec3d9 | 233 | |
17c76198 | 234 | Returns: nothing |
059ec3d9 PH |
235 | */ |
236 | ||
17c76198 PP |
237 | static void |
238 | record_io_error(exim_gnutls_state_st *state, int rc, uschar *when, uschar *text) | |
059ec3d9 | 239 | { |
17c76198 | 240 | const char *msg; |
059ec3d9 | 241 | |
17c76198 PP |
242 | if (rc == GNUTLS_E_FATAL_ALERT_RECEIVED) |
243 | msg = CS string_sprintf("%s: %s", US gnutls_strerror(rc), | |
244 | US gnutls_alert_get_name(gnutls_alert_get(state->session))); | |
245 | else | |
246 | msg = gnutls_strerror(rc); | |
059ec3d9 | 247 | |
17c76198 PP |
248 | tls_error(when, msg, state->host); |
249 | } | |
059ec3d9 | 250 | |
059ec3d9 | 251 | |
059ec3d9 | 252 | |
059ec3d9 | 253 | |
17c76198 PP |
254 | /************************************************* |
255 | * Set various Exim expansion vars * | |
256 | *************************************************/ | |
059ec3d9 | 257 | |
17c76198 PP |
258 | /* We set various Exim global variables from the state, once a session has |
259 | been established. With TLS callouts, may need to change this to stack | |
260 | variables, or just re-call it with the server state after client callout | |
261 | has finished. | |
059ec3d9 | 262 | |
17c76198 PP |
263 | Make sure anything set here is inset in tls_getc(). |
264 | ||
265 | Sets: | |
266 | tls_active fd | |
267 | tls_bits strength indicator | |
268 | tls_certificate_verified bool indicator | |
269 | tls_channelbinding_b64 for some SASL mechanisms | |
270 | tls_cipher a string | |
271 | tls_peerdn a string | |
272 | tls_sni a (UTF-8) string | |
273 | Also: | |
274 | current_global_tls_state for API limitations | |
275 | ||
276 | Argument: | |
277 | state the relevant exim_gnutls_state_st * | |
278 | */ | |
279 | ||
280 | static void | |
281 | extract_exim_vars_from_tls_state(exim_gnutls_state_st *state) | |
282 | { | |
283 | gnutls_protocol_t protocol; | |
284 | gnutls_cipher_algorithm_t cipher; | |
285 | gnutls_kx_algorithm_t kx; | |
286 | gnutls_mac_algorithm_t mac; | |
287 | uschar *p; | |
288 | #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING | |
289 | int old_pool; | |
290 | int rc; | |
291 | gnutls_datum_t channel; | |
292 | #endif | |
293 | ||
294 | current_global_tls_state = state; | |
295 | ||
296 | tls_active = state->fd_out; | |
297 | ||
298 | cipher = gnutls_cipher_get(state->session); | |
299 | /* returns size in "bytes" */ | |
300 | tls_bits = gnutls_cipher_get_key_size(cipher) * 8; | |
301 | ||
302 | if (!*state->cipherbuf) | |
059ec3d9 | 303 | { |
17c76198 PP |
304 | protocol = gnutls_protocol_get_version(state->session); |
305 | mac = gnutls_mac_get(state->session); | |
306 | kx = gnutls_kx_get(state->session); | |
307 | ||
308 | string_format(state->cipherbuf, sizeof(state->cipherbuf), | |
309 | "%s:%s:%u", | |
310 | gnutls_protocol_get_name(protocol), | |
311 | gnutls_cipher_suite_get_name(kx, cipher, mac), | |
312 | tls_bits); | |
313 | ||
314 | /* I don't see a way that spaces could occur, in the current GnuTLS | |
315 | code base, but it was a concern in the old code and perhaps older GnuTLS | |
316 | releases did return "TLS 1.0"; play it safe, just in case. */ | |
317 | for (p = state->cipherbuf; *p != '\0'; ++p) | |
318 | if (isspace(*p)) | |
319 | *p = '-'; | |
059ec3d9 | 320 | } |
17c76198 PP |
321 | tls_cipher = state->cipherbuf; |
322 | ||
323 | DEBUG(D_tls) debug_printf("cipher: %s\n", tls_cipher); | |
324 | ||
325 | tls_certificate_verified = state->peer_cert_verified; | |
059ec3d9 | 326 | |
17c76198 PP |
327 | /* note that tls_channelbinding_b64 is not saved to the spool file, since it's |
328 | only available for use for authenticators while this TLS session is running. */ | |
329 | ||
330 | tls_channelbinding_b64 = NULL; | |
331 | #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING | |
332 | channel.data = NULL; | |
333 | channel.size = 0; | |
334 | rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel); | |
335 | if (rc) { | |
336 | DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc)); | |
337 | } else { | |
338 | old_pool = store_pool; | |
339 | store_pool = POOL_PERM; | |
340 | tls_channelbinding_b64 = auth_b64encode(channel.data, (int)channel.size); | |
341 | store_pool = old_pool; | |
342 | DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage.\n"); | |
343 | } | |
344 | #endif | |
345 | ||
346 | tls_peerdn = state->peerdn; | |
347 | ||
348 | tls_sni = state->received_sni; | |
059ec3d9 PH |
349 | } |
350 | ||
351 | ||
352 | ||
17c76198 | 353 | |
059ec3d9 | 354 | /************************************************* |
575643cd | 355 | * Setup up DH parameters * |
059ec3d9 PH |
356 | *************************************************/ |
357 | ||
575643cd | 358 | /* Generating the D-H parameters may take a long time. They only need to |
059ec3d9 PH |
359 | be re-generated every so often, depending on security policy. What we do is to |
360 | keep these parameters in a file in the spool directory. If the file does not | |
361 | exist, we generate them. This means that it is easy to cause a regeneration. | |
362 | ||
363 | The new file is written as a temporary file and renamed, so that an incomplete | |
364 | file is never present. If two processes both compute some new parameters, you | |
365 | waste a bit of effort, but it doesn't seem worth messing around with locking to | |
366 | prevent this. | |
367 | ||
368 | Argument: | |
369 | host NULL for server, server for client (for error handling) | |
370 | ||
371 | Returns: OK/DEFER/FAIL | |
372 | */ | |
373 | ||
374 | static int | |
17c76198 | 375 | init_server_dh(void) |
059ec3d9 | 376 | { |
17c76198 PP |
377 | int fd, rc; |
378 | unsigned int dh_bits; | |
b5aea5e1 | 379 | gnutls_datum m; |
17c76198 PP |
380 | uschar filename[PATH_MAX]; |
381 | size_t sz; | |
382 | host_item *host = NULL; /* dummy for macros */ | |
383 | const char * const dh_param_fn_ext = "normal"; /* change as dh_bits changes */ | |
059ec3d9 | 384 | |
17c76198 | 385 | DEBUG(D_tls) debug_printf("Initialising GnuTLS server params.\n"); |
059ec3d9 | 386 | |
17c76198 PP |
387 | rc = gnutls_dh_params_init(&dh_server_params); |
388 | exim_gnutls_err_check(US"gnutls_dh_params_init"); | |
059ec3d9 | 389 | |
17c76198 PP |
390 | /* If you change this, also change dh_param_fn_ext so that we can use a |
391 | different filename and ensure we have sufficient bits. */ | |
392 | dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, GNUTLS_SEC_PARAM_NORMAL); | |
393 | if (!dh_bits) | |
394 | return tls_error(US"gnutls_sec_param_to_pk_bits() failed", NULL, NULL); | |
059ec3d9 | 395 | |
17c76198 PP |
396 | if (!string_format(filename, sizeof(filename), |
397 | "%s/gnutls-params-%s", spool_directory, dh_param_fn_ext)) | |
398 | return tls_error(US"overlong filename", NULL, NULL); | |
059ec3d9 | 399 | |
b5aea5e1 | 400 | /* Open the cache file for reading and if successful, read it and set up the |
575643cd | 401 | parameters. */ |
059ec3d9 PH |
402 | |
403 | fd = Uopen(filename, O_RDONLY, 0); | |
b5aea5e1 | 404 | if (fd >= 0) |
059ec3d9 | 405 | { |
b5aea5e1 | 406 | struct stat statbuf; |
17c76198 PP |
407 | FILE *fp; |
408 | int saved_errno; | |
409 | ||
410 | if (fstat(fd, &statbuf) < 0) /* EIO */ | |
411 | { | |
412 | saved_errno = errno; | |
413 | (void)close(fd); | |
414 | return tls_error(US"TLS cache stat failed", strerror(saved_errno), NULL); | |
415 | } | |
416 | if (!S_ISREG(statbuf.st_mode)) | |
b5aea5e1 PH |
417 | { |
418 | (void)close(fd); | |
17c76198 PP |
419 | return tls_error(US"TLS cache not a file", NULL, NULL); |
420 | } | |
421 | fp = fdopen(fd, "rb"); | |
422 | if (!fp) | |
423 | { | |
424 | saved_errno = errno; | |
425 | (void)close(fd); | |
426 | return tls_error(US"fdopen(TLS cache stat fd) failed", | |
427 | strerror(saved_errno), NULL); | |
b5aea5e1 | 428 | } |
059ec3d9 | 429 | |
b5aea5e1 PH |
430 | m.size = statbuf.st_size; |
431 | m.data = malloc(m.size); | |
432 | if (m.data == NULL) | |
17c76198 PP |
433 | { |
434 | fclose(fp); | |
435 | return tls_error(US"malloc failed", strerror(errno), NULL); | |
436 | } | |
437 | sz = fread(m.data, m.size, 1, fp); | |
438 | if (!sz) | |
439 | { | |
440 | saved_errno = errno; | |
441 | fclose(fp); | |
442 | free(m.data); | |
443 | return tls_error(US"fread failed", strerror(saved_errno), NULL); | |
444 | } | |
445 | fclose(fp); | |
b5aea5e1 | 446 | |
17c76198 | 447 | rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM); |
b5aea5e1 | 448 | free(m.data); |
17c76198 PP |
449 | exim_gnutls_err_check(US"gnutls_dh_params_import_pkcs3"); |
450 | DEBUG(D_tls) debug_printf("read D-H parameters from file \"%s\"\n", filename); | |
b5aea5e1 PH |
451 | } |
452 | ||
453 | /* If the file does not exist, fall through to compute new data and cache it. | |
454 | If there was any other opening error, it is serious. */ | |
455 | ||
182ad5cf PH |
456 | else if (errno == ENOENT) |
457 | { | |
17c76198 | 458 | rc = -1; |
182ad5cf | 459 | DEBUG(D_tls) |
17c76198 | 460 | debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename); |
182ad5cf PH |
461 | } |
462 | else | |
17c76198 PP |
463 | return tls_error(string_open_failed(errno, "\"%s\" for reading", filename), |
464 | NULL, NULL); | |
b5aea5e1 PH |
465 | |
466 | /* If ret < 0, either the cache file does not exist, or the data it contains | |
467 | is not useful. One particular case of this is when upgrading from an older | |
468 | release of Exim in which the data was stored in a different format. We don't | |
469 | try to be clever and support both formats; we just regenerate new data in this | |
470 | case. */ | |
471 | ||
17c76198 | 472 | if (rc < 0) |
b5aea5e1 | 473 | { |
17c76198 | 474 | uschar *temp_fn; |
059ec3d9 | 475 | |
17c76198 PP |
476 | if ((PATH_MAX - Ustrlen(filename)) < 10) |
477 | return tls_error(US"Filename too long to generate replacement", | |
478 | CS filename, NULL); | |
059ec3d9 | 479 | |
17c76198 PP |
480 | temp_fn = string_copy(US "%s.XXXXXXX"); |
481 | fd = mkstemp(CS temp_fn); /* modifies temp_fn */ | |
059ec3d9 | 482 | if (fd < 0) |
17c76198 | 483 | return tls_error(US"Unable to open temp file", strerror(errno), NULL); |
059ec3d9 PH |
484 | (void)fchown(fd, exim_uid, exim_gid); /* Probably not necessary */ |
485 | ||
17c76198 PP |
486 | DEBUG(D_tls) debug_printf("generating %d bits Diffie-Hellman key ...\n", dh_bits); |
487 | rc = gnutls_dh_params_generate2(dh_server_params, dh_bits); | |
488 | exim_gnutls_err_check(US"gnutls_dh_params_generate2"); | |
489 | ||
490 | /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time, | |
491 | and I confirmed that a NULL call to get the size first is how the GnuTLS | |
492 | sample apps handle this. */ | |
493 | ||
494 | sz = 0; | |
495 | m.data = NULL; | |
496 | rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM, | |
497 | m.data, &sz); | |
498 | if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER) | |
499 | exim_gnutls_err_check(US"gnutls_dh_params_export_pkcs3(NULL) sizing"); | |
500 | m.size = sz; | |
b5aea5e1 PH |
501 | m.data = malloc(m.size); |
502 | if (m.data == NULL) | |
17c76198 PP |
503 | return tls_error(US"memory allocation failed", strerror(errno), NULL); |
504 | rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM, | |
505 | m.data, &sz); | |
506 | if (rc != GNUTLS_E_SUCCESS) | |
507 | { | |
508 | free(m.data); | |
509 | exim_gnutls_err_check(US"gnutls_dh_params_export_pkcs3() real"); | |
510 | } | |
059ec3d9 | 511 | |
17c76198 PP |
512 | sz = write_to_fd_buf(fd, m.data, (size_t) m.size); |
513 | if (sz != m.size) | |
514 | { | |
515 | free(m.data); | |
516 | return tls_error(US"TLS cache write D-H params failed", | |
517 | strerror(errno), NULL); | |
518 | } | |
b5aea5e1 | 519 | free(m.data); |
17c76198 PP |
520 | sz = write_to_fd_buf(fd, US"\n", 1); |
521 | if (sz != 1) | |
522 | return tls_error(US"TLS cache write D-H params final newline failed", | |
523 | strerror(errno), NULL); | |
524 | ||
525 | rc = close(fd); | |
526 | if (rc) | |
527 | return tls_error(US"TLS cache write close() failed", | |
528 | strerror(errno), NULL); | |
059ec3d9 | 529 | |
17c76198 PP |
530 | if (Urename(temp_fn, filename) < 0) |
531 | return tls_error(string_sprintf("failed to rename \"%s\" as \"%s\"", | |
532 | temp_fn, filename), strerror(errno), NULL); | |
059ec3d9 | 533 | |
17c76198 | 534 | DEBUG(D_tls) debug_printf("wrote D-H parameters to file \"%s\"\n", filename); |
059ec3d9 PH |
535 | } |
536 | ||
17c76198 | 537 | DEBUG(D_tls) debug_printf("initialized server D-H parameters\n"); |
059ec3d9 PH |
538 | return OK; |
539 | } | |
540 | ||
541 | ||
542 | ||
543 | ||
544 | /************************************************* | |
17c76198 | 545 | * Variables re-expanded post-SNI * |
059ec3d9 PH |
546 | *************************************************/ |
547 | ||
17c76198 PP |
548 | /* Called from both server and client code, via tls_init(), and also from |
549 | the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni". | |
550 | ||
551 | We can tell the two apart by state->received_sni being non-NULL in callback. | |
552 | ||
553 | The callback should not call us unless state->trigger_sni_changes is true, | |
554 | which we are responsible for setting on the first pass through. | |
059ec3d9 PH |
555 | |
556 | Arguments: | |
17c76198 | 557 | state exim_gnutls_state_st * |
059ec3d9 PH |
558 | |
559 | Returns: OK/DEFER/FAIL | |
560 | */ | |
561 | ||
562 | static int | |
17c76198 | 563 | tls_expand_session_files(exim_gnutls_state_st *state) |
059ec3d9 PH |
564 | { |
565 | int rc; | |
17c76198 PP |
566 | const host_item *host = state->host; /* macro should be reconsidered? */ |
567 | uschar *saved_tls_certificate = NULL; | |
568 | uschar *saved_tls_privatekey = NULL; | |
569 | uschar *saved_tls_verify_certificates = NULL; | |
570 | uschar *saved_tls_crl = NULL; | |
571 | int cert_count; | |
572 | ||
573 | /* We check for tls_sni *before* expansion. */ | |
574 | if (!state->host) | |
575 | { | |
576 | if (!state->received_sni) | |
577 | { | |
578 | if (Ustrstr(state->tls_certificate, US"tls_sni")) | |
579 | { | |
580 | DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI.\n"); | |
581 | state->trigger_sni_changes = TRUE; | |
582 | } | |
583 | } | |
584 | else | |
585 | { | |
586 | saved_tls_certificate = state->exp_tls_certificate; | |
587 | saved_tls_privatekey = state->exp_tls_privatekey; | |
588 | saved_tls_verify_certificates = state->exp_tls_verify_certificates; | |
589 | saved_tls_crl = state->exp_tls_crl; | |
590 | } | |
591 | } | |
059ec3d9 | 592 | |
17c76198 PP |
593 | /* remember: expand_check_tlsvar() is expand_check() but fiddling with |
594 | state members, assuming consistent naming; and expand_check() returns | |
595 | false if expansion failed, unless expansion was forced to fail. */ | |
059ec3d9 | 596 | |
17c76198 PP |
597 | /* check if we at least have a certificate, before doing expensive |
598 | D-H generation. */ | |
059ec3d9 | 599 | |
17c76198 PP |
600 | if (!expand_check_tlsvar(tls_certificate)) |
601 | return DEFER; | |
059ec3d9 | 602 | |
17c76198 | 603 | /* certificate is mandatory in server, optional in client */ |
059ec3d9 | 604 | |
17c76198 PP |
605 | if ((state->exp_tls_certificate == NULL) || |
606 | (*state->exp_tls_certificate == '\0')) | |
607 | { | |
608 | if (state->host == NULL) | |
609 | return tls_error(US"no TLS server certificate is specified", NULL, NULL); | |
610 | else | |
611 | DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n"); | |
612 | } | |
059ec3d9 | 613 | |
17c76198 | 614 | if (state->tls_privatekey && !expand_check_tlsvar(tls_privatekey)) |
059ec3d9 PH |
615 | return DEFER; |
616 | ||
17c76198 PP |
617 | /* tls_privatekey is optional, defaulting to same file as certificate */ |
618 | ||
619 | if (state->tls_privatekey == NULL || *state->tls_privatekey == '\0') | |
059ec3d9 | 620 | { |
17c76198 PP |
621 | state->tls_privatekey = state->tls_certificate; |
622 | state->exp_tls_privatekey = state->exp_tls_certificate; | |
059ec3d9 | 623 | } |
c91535f3 | 624 | |
059ec3d9 | 625 | |
17c76198 | 626 | if (state->exp_tls_certificate && *state->exp_tls_certificate) |
059ec3d9 | 627 | { |
17c76198 | 628 | BOOL setit = TRUE; |
059ec3d9 | 629 | DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n", |
17c76198 PP |
630 | state->exp_tls_certificate, state->exp_tls_privatekey); |
631 | ||
632 | if (state->received_sni) | |
de365ded | 633 | { |
17c76198 PP |
634 | if ((Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0) && |
635 | (Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0)) | |
636 | { | |
637 | DEBUG(D_tls) debug_printf("cert and key unchanged with SNI.\n"); | |
638 | setit = FALSE; | |
639 | } | |
640 | else | |
641 | { | |
642 | DEBUG(D_tls) debug_printf("SNI changed cert/key pair.\n"); | |
643 | } | |
8e669ac1 | 644 | } |
059ec3d9 | 645 | |
17c76198 PP |
646 | if (setit) |
647 | { | |
648 | rc = gnutls_certificate_set_x509_key_file(state->x509_cred, | |
649 | CS state->exp_tls_certificate, CS state->exp_tls_privatekey, | |
650 | GNUTLS_X509_FMT_PEM); | |
651 | exim_gnutls_err_check( | |
652 | string_sprintf("cert/key setup: cert=%s key=%s", | |
653 | state->exp_tls_certificate, state->exp_tls_privatekey)); | |
654 | } | |
059ec3d9 PH |
655 | } |
656 | ||
657 | /* Set the trusted CAs file if one is provided, and then add the CRL if one is | |
658 | provided. Experiment shows that, if the certificate file is empty, an unhelpful | |
659 | error message is provided. However, if we just refrain from setting anything up | |
660 | in that case, certificate verification fails, which seems to be the correct | |
661 | behaviour. */ | |
662 | ||
17c76198 | 663 | if (state->tls_verify_certificates && *state->tls_verify_certificates) |
059ec3d9 PH |
664 | { |
665 | struct stat statbuf; | |
17c76198 | 666 | BOOL setit_vc = TRUE, setit_crl = TRUE; |
059ec3d9 | 667 | |
17c76198 | 668 | if (!expand_check_tlsvar(tls_verify_certificates)) |
059ec3d9 | 669 | return DEFER; |
17c76198 PP |
670 | if (state->tls_crl && *state->tls_crl) |
671 | if (!expand_check_tlsvar(tls_crl)) | |
672 | return DEFER; | |
059ec3d9 | 673 | |
17c76198 PP |
674 | if (state->received_sni) |
675 | { | |
676 | if (Ustrcmp(state->exp_tls_verify_certificates, saved_tls_verify_certificates) == 0) | |
677 | setit_vc = FALSE; | |
678 | if (Ustrcmp(state->exp_tls_crl, saved_tls_crl) == 0) | |
679 | setit_crl = FALSE; | |
680 | } | |
681 | ||
682 | /* nb: early exit; change if add more expansions to this function */ | |
683 | if (!(setit_vc || setit_crl)) | |
684 | return OK; | |
685 | ||
686 | if (Ustat(state->exp_tls_verify_certificates, &statbuf) < 0) | |
059ec3d9 PH |
687 | { |
688 | log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s " | |
17c76198 PP |
689 | "(tls_verify_certificates): %s", state->exp_tls_verify_certificates, |
690 | strerror(errno)); | |
691 | return DEFER; | |
692 | } | |
693 | ||
694 | if (!S_ISREG(statbuf.st_mode)) | |
695 | { | |
696 | DEBUG(D_tls) | |
697 | debug_printf("verify certificates path is not a file: \"%s\"\n%s\n", | |
698 | state->exp_tls_verify_certificates, | |
699 | S_ISDIR(statbuf.st_mode) | |
700 | ? " it's a directory, that's OpenSSL, this is GnuTLS" | |
701 | : " (not a directory either)"); | |
702 | log_write(0, LOG_MAIN|LOG_PANIC, | |
703 | "tls_verify_certificates \"%s\" is not a file", | |
704 | state->exp_tls_verify_certificates); | |
059ec3d9 PH |
705 | return DEFER; |
706 | } | |
707 | ||
b1c749bb | 708 | DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n", |
17c76198 | 709 | state->exp_tls_verify_certificates, statbuf.st_size); |
059ec3d9 | 710 | |
17c76198 PP |
711 | /* If the CA cert file is empty, there's no point in loading the CRL file, |
712 | as we aren't verifying, so checking for revocation is pointless. */ | |
059ec3d9 PH |
713 | |
714 | if (statbuf.st_size > 0) | |
715 | { | |
17c76198 | 716 | if (setit_vc) |
059ec3d9 | 717 | { |
17c76198 PP |
718 | cert_count = gnutls_certificate_set_x509_trust_file(state->x509_cred, |
719 | CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM); | |
720 | if (cert_count < 0) | |
721 | { | |
722 | rc = cert_count; | |
723 | exim_gnutls_err_check(US"gnutls_certificate_set_x509_trust_file"); | |
724 | } | |
725 | DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n", cert_count); | |
059ec3d9 | 726 | } |
059ec3d9 | 727 | |
17c76198 PP |
728 | if (setit_crl && state->tls_crl && *state->tls_crl) |
729 | { | |
730 | if (state->exp_tls_crl && *state->exp_tls_crl) | |
731 | { | |
732 | DEBUG(D_tls) debug_printf("loading CRL file = %s\n", state->exp_tls_crl); | |
733 | rc = gnutls_certificate_set_x509_crl_file(state->x509_cred, | |
734 | CS state->exp_tls_crl, GNUTLS_X509_FMT_PEM); | |
735 | exim_gnutls_err_check(US"gnutls_certificate_set_x509_crl_file"); | |
736 | } | |
737 | } | |
738 | } /* statbuf.st_size */ | |
739 | } /* tls_verify_certificates */ | |
059ec3d9 | 740 | |
059ec3d9 | 741 | return OK; |
17c76198 | 742 | /* also above, during verify_certificates/crl, during SNI, if unchanged */ |
059ec3d9 PH |
743 | } |
744 | ||
745 | ||
746 | ||
747 | ||
748 | /************************************************* | |
17c76198 | 749 | * Initialize for GnuTLS * |
059ec3d9 PH |
750 | *************************************************/ |
751 | ||
17c76198 PP |
752 | /* Called from both server and client code. In the case of a server, errors |
753 | before actual TLS negotiation return DEFER. | |
059ec3d9 PH |
754 | |
755 | Arguments: | |
17c76198 PP |
756 | host connected host, if client; NULL if server |
757 | certificate certificate file | |
758 | privatekey private key file | |
759 | sni TLS SNI to send, sometimes when client; else NULL | |
760 | cas CA certs file | |
761 | crl CRL file | |
762 | require_ciphers tls_require_ciphers setting | |
059ec3d9 | 763 | |
17c76198 | 764 | Returns: OK/DEFER/FAIL |
059ec3d9 PH |
765 | */ |
766 | ||
17c76198 PP |
767 | static int |
768 | tls_init( | |
769 | const host_item *host, | |
770 | const uschar *certificate, | |
771 | const uschar *privatekey, | |
772 | const uschar *sni, | |
773 | const uschar *cas, | |
774 | const uschar *crl, | |
775 | const uschar *require_ciphers, | |
776 | exim_gnutls_state_st **caller_state) | |
059ec3d9 | 777 | { |
17c76198 PP |
778 | exim_gnutls_state_st *state; |
779 | int rc; | |
780 | size_t sz; | |
781 | const char *errpos; | |
782 | uschar *p; | |
783 | BOOL want_default_priorities; | |
784 | ||
785 | if (!exim_gnutls_base_init_done) | |
059ec3d9 | 786 | { |
17c76198 PP |
787 | DEBUG(D_tls) debug_printf("GnuTLS global init required.\n"); |
788 | ||
789 | rc = gnutls_global_init(); | |
790 | exim_gnutls_err_check(US"gnutls_global_init"); | |
791 | ||
792 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 | |
793 | DEBUG(D_tls) | |
059ec3d9 | 794 | { |
17c76198 PP |
795 | gnutls_global_set_log_function(exim_gnutls_logger_cb); |
796 | /* arbitrarily chosen level; bump upto 9 for more */ | |
797 | gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL); | |
059ec3d9 | 798 | } |
17c76198 PP |
799 | #endif |
800 | ||
801 | exim_gnutls_base_init_done = TRUE; | |
059ec3d9 | 802 | } |
059ec3d9 | 803 | |
17c76198 PP |
804 | if (host) |
805 | { | |
806 | state = &state_client; | |
807 | memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); | |
808 | DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n"); | |
809 | rc = gnutls_init(&state->session, GNUTLS_CLIENT); | |
810 | } | |
811 | else | |
812 | { | |
813 | state = &state_server; | |
814 | memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); | |
815 | DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n"); | |
816 | rc = gnutls_init(&state->session, GNUTLS_SERVER); | |
817 | } | |
818 | exim_gnutls_err_check(US"gnutls_init"); | |
059ec3d9 | 819 | |
17c76198 | 820 | state->host = host; |
059ec3d9 | 821 | |
17c76198 PP |
822 | state->tls_certificate = certificate; |
823 | state->tls_privatekey = privatekey; | |
824 | state->tls_sni = sni; | |
825 | state->tls_verify_certificates = cas; | |
826 | state->tls_crl = crl; | |
059ec3d9 | 827 | |
17c76198 PP |
828 | rc = gnutls_certificate_allocate_credentials(&state->x509_cred); |
829 | exim_gnutls_err_check(US"gnutls_certificate_allocate_credentials"); | |
059ec3d9 | 830 | |
17c76198 PP |
831 | /* This handles the variables that might get re-expanded after TLS SNI; |
832 | that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */ | |
059ec3d9 | 833 | |
17c76198 PP |
834 | DEBUG(D_tls) |
835 | debug_printf("Expanding various TLS configuration options for session credentials.\n"); | |
836 | rc = tls_expand_session_files(state); | |
837 | if (rc != OK) return rc; | |
059ec3d9 | 838 | |
17c76198 PP |
839 | /* Create D-H parameters, or read them from the cache file. This function does |
840 | its own SMTP error messaging. This only happens for the server, TLS D-H ignores | |
841 | client-side params. */ | |
842 | ||
843 | if (!host) | |
059ec3d9 | 844 | { |
17c76198 PP |
845 | rc = init_server_dh(); |
846 | if (rc != OK) return rc; | |
847 | gnutls_certificate_set_dh_params(state->x509_cred, dh_server_params); | |
059ec3d9 | 848 | } |
83da1223 | 849 | |
17c76198 | 850 | /* Link the credentials to the session. */ |
83da1223 | 851 | |
17c76198 PP |
852 | rc = gnutls_credentials_set(state->session, GNUTLS_CRD_CERTIFICATE, state->x509_cred); |
853 | exim_gnutls_err_check(US"gnutls_credentials_set"); | |
83da1223 | 854 | |
17c76198 PP |
855 | /* set SNI in client, only */ |
856 | if (host) | |
857 | { | |
858 | if (!expand_check_tlsvar(tls_sni)) | |
859 | return DEFER; | |
860 | if (state->exp_tls_sni && *state->exp_tls_sni) | |
861 | { | |
862 | DEBUG(D_tls) | |
863 | debug_printf("Setting TLS client SNI to \"%s\"\n", state->exp_tls_sni); | |
864 | sz = Ustrlen(state->exp_tls_sni); | |
865 | rc = gnutls_server_name_set(state->session, | |
866 | GNUTLS_NAME_DNS, state->exp_tls_sni, sz); | |
867 | exim_gnutls_err_check(US"gnutls_server_name_set"); | |
868 | } | |
869 | } | |
870 | else if (state->tls_sni) | |
871 | DEBUG(D_tls) debug_printf("*** PROBABLY A BUG *** " \ | |
872 | "have an SNI set for a client [%s]\n", state->tls_sni); | |
83da1223 | 873 | |
17c76198 PP |
874 | /* This is the priority string support, |
875 | http://www.gnu.org/software/gnutls/manual/html_node/Priority-Strings.html | |
876 | and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols. | |
877 | This was backwards incompatible, but means Exim no longer needs to track | |
878 | all algorithms and provide string forms for them. */ | |
83da1223 | 879 | |
17c76198 | 880 | want_default_priorities = TRUE; |
83da1223 | 881 | |
17c76198 | 882 | if (state->tls_require_ciphers && *state->tls_require_ciphers) |
83da1223 | 883 | { |
17c76198 PP |
884 | if (!expand_check_tlsvar(tls_require_ciphers)) |
885 | return DEFER; | |
886 | if (state->exp_tls_require_ciphers && *state->exp_tls_require_ciphers) | |
83da1223 | 887 | { |
17c76198 PP |
888 | DEBUG(D_tls) debug_printf("GnuTLS session cipher/priority \"%s\"\n", |
889 | state->exp_tls_require_ciphers); | |
890 | ||
891 | rc = gnutls_priority_init(&state->priority_cache, | |
892 | CS state->exp_tls_require_ciphers, &errpos); | |
893 | want_default_priorities = FALSE; | |
894 | p = state->exp_tls_require_ciphers; | |
83da1223 PH |
895 | } |
896 | } | |
17c76198 PP |
897 | if (want_default_priorities) |
898 | { | |
899 | rc = gnutls_priority_init(&state->priority_cache, | |
900 | exim_default_gnutls_priority, &errpos); | |
901 | p = US exim_default_gnutls_priority; | |
902 | } | |
83da1223 | 903 | |
17c76198 PP |
904 | exim_gnutls_err_check(string_sprintf( |
905 | "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"", | |
906 | p, errpos - CS p, errpos)); | |
907 | ||
908 | rc = gnutls_priority_set(state->session, state->priority_cache); | |
909 | exim_gnutls_err_check(US"gnutls_priority_set"); | |
910 | ||
911 | gnutls_db_set_cache_expiration(state->session, ssl_session_timeout); | |
912 | ||
913 | /* Reduce security in favour of increased compatibility, if the admin | |
914 | decides to make that trade-off. */ | |
915 | if (gnutls_compat_mode) | |
83da1223 | 916 | { |
17c76198 PP |
917 | #if LIBGNUTLS_VERSION_NUMBER >= 0x020104 |
918 | DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n"); | |
919 | gnutls_session_enable_compatibility_mode(state->session); | |
920 | #else | |
921 | DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n"); | |
922 | #endif | |
83da1223 PH |
923 | } |
924 | ||
17c76198 PP |
925 | *caller_state = state; |
926 | /* needs to happen before callbacks during handshake */ | |
927 | current_global_tls_state = state; | |
928 | return OK; | |
83da1223 PH |
929 | } |
930 | ||
931 | ||
932 | ||
933 | ||
059ec3d9 | 934 | /************************************************* |
17c76198 | 935 | * Extract peer information * |
059ec3d9 PH |
936 | *************************************************/ |
937 | ||
17c76198 PP |
938 | /* Called from both server and client code. |
939 | Only this is allowed to set state->peerdn and we use that to detect double-calls. | |
059ec3d9 PH |
940 | |
941 | Arguments: | |
17c76198 | 942 | state exim_gnutls_state_st * |
059ec3d9 | 943 | |
17c76198 | 944 | Returns: OK/DEFER/FAIL |
059ec3d9 PH |
945 | */ |
946 | ||
17c76198 PP |
947 | static int |
948 | peer_status(exim_gnutls_state_st *state) | |
059ec3d9 | 949 | { |
17c76198 PP |
950 | const gnutls_datum *cert_list; |
951 | int rc; | |
952 | unsigned int cert_list_size = 0; | |
953 | gnutls_certificate_type_t ct; | |
954 | gnutls_x509_crt_t crt; | |
955 | uschar *dn_buf; | |
956 | size_t sz; | |
059ec3d9 | 957 | |
17c76198 PP |
958 | if (state->peerdn) |
959 | return OK; | |
059ec3d9 | 960 | |
17c76198 | 961 | state->peerdn = US"unknown"; |
059ec3d9 | 962 | |
17c76198 | 963 | cert_list = gnutls_certificate_get_peers(state->session, &cert_list_size); |
83da1223 | 964 | |
17c76198 PP |
965 | if (cert_list == NULL || cert_list_size == 0) |
966 | { | |
967 | state->peerdn = US"unknown (no certificate)"; | |
968 | DEBUG(D_tls) debug_printf("TLS: no certificate from peer (%p & %d)\n", | |
969 | cert_list, cert_list_size); | |
970 | if (state->verify_requirement == VERIFY_REQUIRED) | |
971 | return tls_error(US"certificate verification failed", | |
972 | "no certificate received from peer", state->host); | |
973 | return OK; | |
974 | } | |
059ec3d9 | 975 | |
17c76198 PP |
976 | ct = gnutls_certificate_type_get(state->session); |
977 | if (ct != GNUTLS_CRT_X509) | |
059ec3d9 | 978 | { |
17c76198 PP |
979 | const char *ctn = gnutls_certificate_type_get_name(ct); |
980 | state->peerdn = string_sprintf("unknown (type %s)", ctn); | |
981 | DEBUG(D_tls) | |
982 | debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn); | |
983 | if (state->verify_requirement == VERIFY_REQUIRED) | |
984 | return tls_error(US"certificate verification not possible, unhandled type", | |
985 | ctn, state->host); | |
986 | return OK; | |
83da1223 | 987 | } |
059ec3d9 | 988 | |
17c76198 PP |
989 | #define exim_gnutls_peer_err(Label) do { \ |
990 | if (rc != GNUTLS_E_SUCCESS) { \ | |
991 | DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", (Label), gnutls_strerror(rc)); \ | |
992 | if (state->verify_requirement == VERIFY_REQUIRED) { return tls_error((Label), gnutls_strerror(rc), state->host); } \ | |
993 | return OK; } } while (0) | |
994 | ||
995 | rc = gnutls_x509_crt_init(&crt); | |
996 | exim_gnutls_peer_err(US"gnutls_x509_crt_init (crt)"); | |
997 | ||
998 | rc = gnutls_x509_crt_import(crt, &cert_list[0], GNUTLS_X509_FMT_DER); | |
999 | exim_gnutls_peer_err(US"failed to import certificate [gnutls_x509_crt_import(cert 0)]"); | |
1000 | sz = 0; | |
1001 | rc = gnutls_x509_crt_get_dn(crt, NULL, &sz); | |
1002 | if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER) | |
83da1223 | 1003 | { |
17c76198 PP |
1004 | exim_gnutls_peer_err(US"getting size for cert DN failed"); |
1005 | return FAIL; /* should not happen */ | |
059ec3d9 | 1006 | } |
17c76198 PP |
1007 | dn_buf = store_get_perm(sz); |
1008 | rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz); | |
1009 | exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]"); | |
1010 | state->peerdn = dn_buf; | |
1011 | ||
1012 | return OK; | |
1013 | #undef exim_gnutls_peer_err | |
1014 | } | |
059ec3d9 | 1015 | |
059ec3d9 | 1016 | |
059ec3d9 | 1017 | |
059ec3d9 | 1018 | |
17c76198 PP |
1019 | /************************************************* |
1020 | * Verify peer certificate * | |
1021 | *************************************************/ | |
059ec3d9 | 1022 | |
17c76198 PP |
1023 | /* Called from both server and client code. |
1024 | *Should* be using a callback registered with | |
1025 | gnutls_certificate_set_verify_function() to fail the handshake if we dislike | |
1026 | the peer information, but that's too new for some OSes. | |
059ec3d9 | 1027 | |
17c76198 PP |
1028 | Arguments: |
1029 | state exim_gnutls_state_st * | |
1030 | error where to put an error message | |
059ec3d9 | 1031 | |
17c76198 PP |
1032 | Returns: |
1033 | FALSE if the session should be rejected | |
1034 | TRUE if the cert is okay or we just don't care | |
1035 | */ | |
059ec3d9 | 1036 | |
17c76198 PP |
1037 | static BOOL |
1038 | verify_certificate(exim_gnutls_state_st *state, const char **error) | |
1039 | { | |
1040 | int rc; | |
1041 | unsigned int verify; | |
1042 | ||
1043 | *error = NULL; | |
1044 | ||
1045 | rc = peer_status(state); | |
1046 | if (rc != OK) | |
e6060e2c | 1047 | { |
17c76198 PP |
1048 | verify = GNUTLS_CERT_INVALID; |
1049 | *error = "not supplied"; | |
1050 | } | |
1051 | else | |
1052 | { | |
1053 | rc = gnutls_certificate_verify_peers2(state->session, &verify); | |
e6060e2c NM |
1054 | } |
1055 | ||
17c76198 PP |
1056 | /* Handle the result of verification. INVALID seems to be set as well |
1057 | as REVOKED, but leave the test for both. */ | |
059ec3d9 | 1058 | |
17c76198 PP |
1059 | if ((rc < 0) || (verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED)) != 0) |
1060 | { | |
1061 | state->peer_cert_verified = FALSE; | |
1062 | if (*error == NULL) | |
1063 | *error = ((verify & GNUTLS_CERT_REVOKED) != 0) ? "revoked" : "invalid"; | |
059ec3d9 | 1064 | |
17c76198 PP |
1065 | DEBUG(D_tls) |
1066 | debug_printf("TLS certificate verification failed (%s): peerdn=%s\n", | |
1067 | *error, state->peerdn); | |
059ec3d9 | 1068 | |
17c76198 PP |
1069 | if (state->verify_requirement == VERIFY_REQUIRED) |
1070 | { | |
1071 | gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE); | |
1072 | return FALSE; | |
1073 | } | |
1074 | DEBUG(D_tls) | |
1075 | debug_printf("TLS verify failure overriden (host in tls_try_verify_hosts)\n"); | |
1076 | } | |
1077 | else | |
1078 | { | |
1079 | state->peer_cert_verified = TRUE; | |
1080 | DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=%s\n", state->peerdn); | |
1081 | } | |
059ec3d9 | 1082 | |
17c76198 | 1083 | tls_peerdn = state->peerdn; |
059ec3d9 | 1084 | |
17c76198 PP |
1085 | return TRUE; |
1086 | } | |
059ec3d9 | 1087 | |
17c76198 PP |
1088 | |
1089 | ||
1090 | ||
1091 | /* ------------------------------------------------------------------------ */ | |
1092 | /* Callbacks */ | |
1093 | ||
1094 | /* Logging function which can be registered with | |
1095 | * gnutls_global_set_log_function() | |
1096 | * gnutls_global_set_log_level() 0..9 | |
1097 | */ | |
059ec3d9 | 1098 | static void |
17c76198 | 1099 | exim_gnutls_logger_cb(int level, const char *message) |
059ec3d9 | 1100 | { |
17c76198 PP |
1101 | DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s\n", level, message); |
1102 | } | |
059ec3d9 | 1103 | |
059ec3d9 | 1104 | |
17c76198 PP |
1105 | /* Called after client hello, should handle SNI work. |
1106 | This will always set tls_sni (state->received_sni) if available, | |
1107 | and may trigger presenting different certificates, | |
1108 | if state->trigger_sni_changes is TRUE. | |
059ec3d9 | 1109 | |
17c76198 PP |
1110 | Should be registered with |
1111 | gnutls_handshake_set_post_client_hello_function() | |
059ec3d9 | 1112 | |
17c76198 PP |
1113 | "This callback must return 0 on success or a gnutls error code to terminate the |
1114 | handshake.". | |
059ec3d9 | 1115 | |
17c76198 PP |
1116 | For inability to get SNI information, we return 0. |
1117 | We only return non-zero if re-setup failed. | |
1118 | */ | |
44bbabb5 | 1119 | |
17c76198 PP |
1120 | static int |
1121 | exim_sni_handling_cb(gnutls_session_t session) | |
1122 | { | |
1123 | char sni_name[MAX_HOST_LEN]; | |
1124 | size_t data_len = MAX_HOST_LEN; | |
1125 | exim_gnutls_state_st *state = current_global_tls_state; | |
1126 | unsigned int sni_type; | |
1127 | int rc, old_pool; | |
1128 | ||
1129 | rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0); | |
1130 | exim_gnutls_err_debugreturn0("gnutls_server_name_get()"); | |
1131 | if (sni_type != GNUTLS_NAME_DNS) | |
1132 | { | |
1133 | DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type); | |
1134 | return 0; | |
1135 | } | |
44bbabb5 | 1136 | |
17c76198 PP |
1137 | /* We now have a UTF-8 string in sni_name */ |
1138 | old_pool = store_pool; | |
1139 | store_pool = POOL_PERM; | |
1140 | state->received_sni = string_copyn(US sni_name, data_len); | |
1141 | store_pool = old_pool; | |
1142 | ||
1143 | /* We set this one now so that variable expansions below will work */ | |
1144 | tls_sni = state->received_sni; | |
1145 | ||
1146 | DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name, | |
1147 | state->trigger_sni_changes ? "" : " (unused for certificate selection)"); | |
1148 | ||
1149 | if (!state->trigger_sni_changes) | |
1150 | return 0; | |
1151 | ||
1152 | rc = tls_expand_session_files(state); | |
1153 | if (rc != OK) | |
1154 | { | |
1155 | /* If the setup of certs/etc failed before handshake, TLS would not have | |
1156 | been offered. The best we can do now is abort. */ | |
1157 | return GNUTLS_E_APPLICATION_ERROR_MIN; | |
1158 | } | |
1159 | ||
1160 | rc = gnutls_credentials_set(state->session, GNUTLS_CRD_CERTIFICATE, state->x509_cred); | |
1161 | return (rc == GNUTLS_E_SUCCESS) ? 0 : rc; | |
059ec3d9 PH |
1162 | } |
1163 | ||
1164 | ||
1165 | ||
17c76198 PP |
1166 | |
1167 | /* ------------------------------------------------------------------------ */ | |
1168 | /* Exported functions */ | |
1169 | ||
1170 | ||
1171 | ||
1172 | ||
059ec3d9 PH |
1173 | /************************************************* |
1174 | * Start a TLS session in a server * | |
1175 | *************************************************/ | |
1176 | ||
1177 | /* This is called when Exim is running as a server, after having received | |
1178 | the STARTTLS command. It must respond to that command, and then negotiate | |
1179 | a TLS session. | |
1180 | ||
1181 | Arguments: | |
83da1223 | 1182 | require_ciphers list of allowed ciphers or NULL |
059ec3d9 PH |
1183 | |
1184 | Returns: OK on success | |
1185 | DEFER for errors before the start of the negotiation | |
1186 | FAIL for errors during the negotation; the server can't | |
1187 | continue running. | |
1188 | */ | |
1189 | ||
1190 | int | |
17c76198 | 1191 | tls_server_start(const uschar *require_ciphers) |
059ec3d9 PH |
1192 | { |
1193 | int rc; | |
7199e1ee | 1194 | const char *error; |
17c76198 | 1195 | exim_gnutls_state_st *state = NULL; |
059ec3d9 PH |
1196 | |
1197 | /* Check for previous activation */ | |
17c76198 | 1198 | /* nb: this will not be TLS callout safe, needs reworking as part of that. */ |
059ec3d9 PH |
1199 | |
1200 | if (tls_active >= 0) | |
1201 | { | |
17c76198 | 1202 | tls_error(US"STARTTLS received after TLS started", "", NULL); |
059ec3d9 PH |
1203 | smtp_printf("554 Already in TLS\r\n"); |
1204 | return FAIL; | |
1205 | } | |
1206 | ||
1207 | /* Initialize the library. If it fails, it will already have logged the error | |
1208 | and sent an SMTP response. */ | |
1209 | ||
17c76198 | 1210 | DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n"); |
059ec3d9 | 1211 | |
17c76198 PP |
1212 | rc = tls_init(NULL, tls_certificate, tls_privatekey, |
1213 | NULL, tls_verify_certificates, tls_crl, | |
1214 | require_ciphers, &state); | |
059ec3d9 PH |
1215 | if (rc != OK) return rc; |
1216 | ||
059ec3d9 PH |
1217 | /* If this is a host for which certificate verification is mandatory or |
1218 | optional, set up appropriately. */ | |
1219 | ||
059ec3d9 | 1220 | if (verify_check_host(&tls_verify_hosts) == OK) |
17c76198 PP |
1221 | { |
1222 | DEBUG(D_tls) debug_printf("TLS: a client certificate will be required.\n"); | |
1223 | state->verify_requirement = VERIFY_REQUIRED; | |
1224 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE); | |
1225 | } | |
059ec3d9 | 1226 | else if (verify_check_host(&tls_try_verify_hosts) == OK) |
17c76198 PP |
1227 | { |
1228 | DEBUG(D_tls) debug_printf("TLS: a client certificate will be requested but not required.\n"); | |
1229 | state->verify_requirement = VERIFY_OPTIONAL; | |
1230 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST); | |
1231 | } | |
1232 | else | |
1233 | { | |
1234 | DEBUG(D_tls) debug_printf("TLS: a client certificate will not be requested.\n"); | |
1235 | state->verify_requirement = VERIFY_NONE; | |
1236 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE); | |
1237 | } | |
059ec3d9 | 1238 | |
17c76198 PP |
1239 | /* Register SNI handling; always, even if not in tls_certificate, so that the |
1240 | expansion variable $tls_sni is always available. */ | |
059ec3d9 | 1241 | |
17c76198 PP |
1242 | gnutls_handshake_set_post_client_hello_function(state->session, |
1243 | exim_sni_handling_cb); | |
059ec3d9 PH |
1244 | |
1245 | /* Set context and tell client to go ahead, except in the case of TLS startup | |
1246 | on connection, where outputting anything now upsets the clients and tends to | |
1247 | make them disconnect. We need to have an explicit fflush() here, to force out | |
1248 | the response. Other smtp_printf() calls do not need it, because in non-TLS | |
1249 | mode, the fflush() happens when smtp_getc() is called. */ | |
1250 | ||
1251 | if (!tls_on_connect) | |
1252 | { | |
1253 | smtp_printf("220 TLS go ahead\r\n"); | |
1254 | fflush(smtp_out); | |
1255 | } | |
1256 | ||
1257 | /* Now negotiate the TLS session. We put our own timer on it, since it seems | |
1258 | that the GnuTLS library doesn't. */ | |
1259 | ||
17c76198 PP |
1260 | gnutls_transport_set_ptr2(state->session, |
1261 | (gnutls_transport_ptr)fileno(smtp_in), | |
1262 | (gnutls_transport_ptr)fileno(smtp_out)); | |
1263 | state->fd_in = fileno(smtp_in); | |
1264 | state->fd_out = fileno(smtp_out); | |
059ec3d9 PH |
1265 | |
1266 | sigalrm_seen = FALSE; | |
1267 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
17c76198 PP |
1268 | do |
1269 | { | |
1270 | rc = gnutls_handshake(state->session); | |
1271 | } while ((rc == GNUTLS_E_AGAIN) || (rc == GNUTLS_E_INTERRUPTED)); | |
059ec3d9 PH |
1272 | alarm(0); |
1273 | ||
17c76198 | 1274 | if (rc != GNUTLS_E_SUCCESS) |
059ec3d9 | 1275 | { |
17c76198 PP |
1276 | tls_error(US"gnutls_handshake", |
1277 | sigalrm_seen ? "timed out" : gnutls_strerror(rc), NULL); | |
059ec3d9 PH |
1278 | /* It seems that, except in the case of a timeout, we have to close the |
1279 | connection right here; otherwise if the other end is running OpenSSL it hangs | |
1280 | until the server times out. */ | |
1281 | ||
1282 | if (!sigalrm_seen) | |
1283 | { | |
f1e894f3 PH |
1284 | (void)fclose(smtp_out); |
1285 | (void)fclose(smtp_in); | |
059ec3d9 PH |
1286 | } |
1287 | ||
1288 | return FAIL; | |
1289 | } | |
1290 | ||
1291 | DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n"); | |
1292 | ||
17c76198 PP |
1293 | /* Verify after the fact */ |
1294 | ||
1295 | if (state->verify_requirement != VERIFY_NONE) | |
059ec3d9 | 1296 | { |
17c76198 PP |
1297 | if (!verify_certificate(state, &error)) |
1298 | { | |
1299 | if (state->verify_requirement == VERIFY_OPTIONAL) | |
1300 | { | |
1301 | DEBUG(D_tls) | |
1302 | debug_printf("TLS: continuing on only because verification was optional, after: %s\n", | |
1303 | error); | |
1304 | } | |
1305 | else | |
1306 | { | |
1307 | tls_error(US"certificate verification failed", error, NULL); | |
1308 | return FAIL; | |
1309 | } | |
1310 | } | |
059ec3d9 PH |
1311 | } |
1312 | ||
17c76198 PP |
1313 | /* Figure out peer DN, and if authenticated, etc. */ |
1314 | ||
1315 | rc = peer_status(state); | |
1316 | if (rc != OK) return rc; | |
1317 | ||
1318 | /* Sets various Exim expansion variables; always safe within server */ | |
1319 | ||
1320 | extract_exim_vars_from_tls_state(state); | |
059ec3d9 PH |
1321 | |
1322 | /* TLS has been set up. Adjust the input functions to read via TLS, | |
1323 | and initialize appropriately. */ | |
1324 | ||
17c76198 | 1325 | state->xfer_buffer = store_malloc(ssl_xfer_buffer_size); |
059ec3d9 PH |
1326 | |
1327 | receive_getc = tls_getc; | |
1328 | receive_ungetc = tls_ungetc; | |
1329 | receive_feof = tls_feof; | |
1330 | receive_ferror = tls_ferror; | |
58eb016e | 1331 | receive_smtp_buffered = tls_smtp_buffered; |
059ec3d9 | 1332 | |
059ec3d9 PH |
1333 | return OK; |
1334 | } | |
1335 | ||
1336 | ||
1337 | ||
1338 | ||
1339 | /************************************************* | |
1340 | * Start a TLS session in a client * | |
1341 | *************************************************/ | |
1342 | ||
1343 | /* Called from the smtp transport after STARTTLS has been accepted. | |
1344 | ||
1345 | Arguments: | |
1346 | fd the fd of the connection | |
1347 | host connected host (for messages) | |
83da1223 | 1348 | addr the first address (not used) |
17c76198 | 1349 | dhparam DH parameter file (ignored, we're a client) |
059ec3d9 PH |
1350 | certificate certificate file |
1351 | privatekey private key file | |
3f0945ff | 1352 | sni TLS SNI to send to remote host |
059ec3d9 PH |
1353 | verify_certs file for certificate verify |
1354 | verify_crl CRL for verify | |
83da1223 | 1355 | require_ciphers list of allowed ciphers or NULL |
059ec3d9 PH |
1356 | timeout startup timeout |
1357 | ||
1358 | Returns: OK/DEFER/FAIL (because using common functions), | |
1359 | but for a client, DEFER and FAIL have the same meaning | |
1360 | */ | |
1361 | ||
1362 | int | |
17c76198 PP |
1363 | tls_client_start(int fd, host_item *host, |
1364 | address_item *addr ARG_UNUSED, uschar *dhparam ARG_UNUSED, | |
1365 | uschar *certificate, uschar *privatekey, uschar *sni, | |
1366 | uschar *verify_certs, uschar *verify_crl, | |
1367 | uschar *require_ciphers, int timeout) | |
059ec3d9 | 1368 | { |
059ec3d9 | 1369 | int rc; |
17c76198 PP |
1370 | const char *error; |
1371 | exim_gnutls_state_st *state = NULL; | |
059ec3d9 | 1372 | |
17c76198 | 1373 | DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", fd); |
059ec3d9 | 1374 | |
17c76198 PP |
1375 | rc = tls_init(host, certificate, privatekey, |
1376 | sni, verify_certs, verify_crl, require_ciphers, &state); | |
059ec3d9 PH |
1377 | if (rc != OK) return rc; |
1378 | ||
17c76198 | 1379 | gnutls_dh_set_prime_bits(state->session, EXIM_CLIENT_DH_MIN_BITS); |
83da1223 | 1380 | |
17c76198 PP |
1381 | if (verify_certs == NULL) |
1382 | { | |
1383 | DEBUG(D_tls) debug_printf("TLS: server certificate verification not required\n"); | |
1384 | state->verify_requirement = VERIFY_NONE; | |
1385 | /* we still ask for it, to log it, etc */ | |
1386 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST); | |
1387 | } | |
1388 | else | |
1389 | { | |
1390 | DEBUG(D_tls) debug_printf("TLS: server certificate verification required\n"); | |
1391 | state->verify_requirement = VERIFY_REQUIRED; | |
1392 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE); | |
1393 | } | |
059ec3d9 | 1394 | |
17c76198 PP |
1395 | gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr)fd); |
1396 | state->fd_in = fd; | |
1397 | state->fd_out = fd; | |
059ec3d9 PH |
1398 | |
1399 | /* There doesn't seem to be a built-in timeout on connection. */ | |
1400 | ||
1401 | sigalrm_seen = FALSE; | |
1402 | alarm(timeout); | |
17c76198 PP |
1403 | do |
1404 | { | |
1405 | rc = gnutls_handshake(state->session); | |
1406 | } while ((rc == GNUTLS_E_AGAIN) || (rc == GNUTLS_E_INTERRUPTED)); | |
059ec3d9 PH |
1407 | alarm(0); |
1408 | ||
17c76198 | 1409 | DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n"); |
059ec3d9 | 1410 | |
17c76198 | 1411 | /* Verify late */ |
059ec3d9 | 1412 | |
17c76198 PP |
1413 | if (state->verify_requirement != VERIFY_NONE && |
1414 | !verify_certificate(state, &error)) | |
1415 | return tls_error(US"certificate verification failed", error, state->host); | |
059ec3d9 | 1416 | |
17c76198 | 1417 | /* Figure out peer DN, and if authenticated, etc. */ |
059ec3d9 | 1418 | |
17c76198 PP |
1419 | rc = peer_status(state); |
1420 | if (rc != OK) return rc; | |
059ec3d9 | 1421 | |
17c76198 | 1422 | /* Sets various Exim expansion variables; always safe within server */ |
059ec3d9 | 1423 | |
17c76198 | 1424 | extract_exim_vars_from_tls_state(state); |
059ec3d9 | 1425 | |
059ec3d9 PH |
1426 | return OK; |
1427 | } | |
1428 | ||
1429 | ||
1430 | ||
17c76198 | 1431 | |
059ec3d9 | 1432 | /************************************************* |
17c76198 | 1433 | * Close down a TLS session * |
059ec3d9 PH |
1434 | *************************************************/ |
1435 | ||
17c76198 PP |
1436 | /* This is also called from within a delivery subprocess forked from the |
1437 | daemon, to shut down the TLS library, without actually doing a shutdown (which | |
1438 | would tamper with the TLS session in the parent process). | |
059ec3d9 | 1439 | |
17c76198 PP |
1440 | Arguments: TRUE if gnutls_bye is to be called |
1441 | Returns: nothing | |
059ec3d9 PH |
1442 | */ |
1443 | ||
17c76198 PP |
1444 | void |
1445 | tls_close(BOOL shutdown) | |
059ec3d9 | 1446 | { |
17c76198 | 1447 | exim_gnutls_state_st *state = current_global_tls_state; |
059ec3d9 | 1448 | |
17c76198 PP |
1449 | if (tls_active < 0) return; /* TLS was not active */ |
1450 | ||
1451 | if (shutdown) | |
1452 | { | |
1453 | DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS\n"); | |
1454 | gnutls_bye(state->session, GNUTLS_SHUT_WR); | |
1455 | } | |
1456 | ||
1457 | gnutls_deinit(state->session); | |
1458 | ||
1459 | memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); | |
1460 | ||
1461 | if ((state_server.session == NULL) && (state_client.session == NULL)) | |
1462 | { | |
1463 | gnutls_global_deinit(); | |
1464 | exim_gnutls_base_init_done = FALSE; | |
1465 | } | |
7199e1ee | 1466 | |
17c76198 | 1467 | tls_active = -1; |
059ec3d9 PH |
1468 | } |
1469 | ||
1470 | ||
1471 | ||
17c76198 | 1472 | |
059ec3d9 PH |
1473 | /************************************************* |
1474 | * TLS version of getc * | |
1475 | *************************************************/ | |
1476 | ||
1477 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, | |
1478 | it refills the buffer via the GnuTLS reading function. | |
1479 | ||
17c76198 PP |
1480 | This feeds DKIM and should be used for all message-body reads. |
1481 | ||
059ec3d9 PH |
1482 | Arguments: none |
1483 | Returns: the next character or EOF | |
1484 | */ | |
1485 | ||
1486 | int | |
1487 | tls_getc(void) | |
1488 | { | |
17c76198 PP |
1489 | exim_gnutls_state_st *state = current_global_tls_state; |
1490 | if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm) | |
059ec3d9 | 1491 | { |
17c76198 | 1492 | ssize_t inbytes; |
059ec3d9 | 1493 | |
17c76198 PP |
1494 | DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%p, %p, %u)\n", |
1495 | state->session, state->xfer_buffer, ssl_xfer_buffer_size); | |
059ec3d9 PH |
1496 | |
1497 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
17c76198 | 1498 | inbytes = gnutls_record_recv(state->session, state->xfer_buffer, |
059ec3d9 PH |
1499 | ssl_xfer_buffer_size); |
1500 | alarm(0); | |
1501 | ||
1502 | /* A zero-byte return appears to mean that the TLS session has been | |
1503 | closed down, not that the socket itself has been closed down. Revert to | |
1504 | non-TLS handling. */ | |
1505 | ||
1506 | if (inbytes == 0) | |
1507 | { | |
1508 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); | |
1509 | ||
1510 | receive_getc = smtp_getc; | |
1511 | receive_ungetc = smtp_ungetc; | |
1512 | receive_feof = smtp_feof; | |
1513 | receive_ferror = smtp_ferror; | |
58eb016e | 1514 | receive_smtp_buffered = smtp_buffered; |
059ec3d9 | 1515 | |
17c76198 PP |
1516 | gnutls_deinit(state->session); |
1517 | state->session = NULL; | |
059ec3d9 | 1518 | tls_active = -1; |
17c76198 PP |
1519 | tls_bits = 0; |
1520 | tls_certificate_verified = FALSE; | |
1521 | tls_channelbinding_b64 = NULL; | |
059ec3d9 PH |
1522 | tls_cipher = NULL; |
1523 | tls_peerdn = NULL; | |
1524 | ||
1525 | return smtp_getc(); | |
1526 | } | |
1527 | ||
1528 | /* Handle genuine errors */ | |
1529 | ||
1530 | else if (inbytes < 0) | |
1531 | { | |
17c76198 PP |
1532 | record_io_error(state, (int) inbytes, US"recv", NULL); |
1533 | state->xfer_error = 1; | |
059ec3d9 PH |
1534 | return EOF; |
1535 | } | |
80a47a2c | 1536 | #ifndef DISABLE_DKIM |
17c76198 | 1537 | dkim_exim_verify_feed(state->xfer_buffer, inbytes); |
80a47a2c | 1538 | #endif |
17c76198 PP |
1539 | state->xfer_buffer_hwm = (int) inbytes; |
1540 | state->xfer_buffer_lwm = 0; | |
059ec3d9 PH |
1541 | } |
1542 | ||
059ec3d9 PH |
1543 | /* Something in the buffer; return next uschar */ |
1544 | ||
17c76198 | 1545 | return state->xfer_buffer[state->xfer_buffer_lwm++]; |
059ec3d9 PH |
1546 | } |
1547 | ||
1548 | ||
1549 | ||
17c76198 | 1550 | |
059ec3d9 PH |
1551 | /************************************************* |
1552 | * Read bytes from TLS channel * | |
1553 | *************************************************/ | |
1554 | ||
17c76198 PP |
1555 | /* This does not feed DKIM, so if the caller uses this for reading message body, |
1556 | then the caller must feed DKIM. | |
059ec3d9 PH |
1557 | Arguments: |
1558 | buff buffer of data | |
1559 | len size of buffer | |
1560 | ||
1561 | Returns: the number of bytes read | |
1562 | -1 after a failed read | |
1563 | */ | |
1564 | ||
1565 | int | |
1566 | tls_read(uschar *buff, size_t len) | |
1567 | { | |
17c76198 PP |
1568 | exim_gnutls_state_st *state = current_global_tls_state; |
1569 | ssize_t inbytes; | |
059ec3d9 | 1570 | |
17c76198 PP |
1571 | if (len > INT_MAX) |
1572 | len = INT_MAX; | |
059ec3d9 | 1573 | |
17c76198 PP |
1574 | if (state->xfer_buffer_lwm < state->xfer_buffer_hwm) |
1575 | DEBUG(D_tls) | |
1576 | debug_printf("*** PROBABLY A BUG *** " \ | |
1577 | "tls_read() called with data in the tls_getc() buffer, %d ignored\n", | |
1578 | state->xfer_buffer_hwm - state->xfer_buffer_lwm); | |
1579 | ||
1580 | DEBUG(D_tls) | |
1581 | debug_printf("Calling gnutls_record_recv(%p, %p, " SIZE_T_FMT ")\n", | |
1582 | state->session, buff, len); | |
1583 | ||
1584 | inbytes = gnutls_record_recv(state->session, buff, len); | |
059ec3d9 PH |
1585 | if (inbytes > 0) return inbytes; |
1586 | if (inbytes == 0) | |
1587 | { | |
1588 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); | |
1589 | } | |
17c76198 | 1590 | else record_io_error(state, (int)inbytes, US"recv", NULL); |
059ec3d9 PH |
1591 | |
1592 | return -1; | |
1593 | } | |
1594 | ||
1595 | ||
1596 | ||
17c76198 | 1597 | |
059ec3d9 PH |
1598 | /************************************************* |
1599 | * Write bytes down TLS channel * | |
1600 | *************************************************/ | |
1601 | ||
1602 | /* | |
1603 | Arguments: | |
1604 | buff buffer of data | |
1605 | len number of bytes | |
1606 | ||
1607 | Returns: the number of bytes after a successful write, | |
1608 | -1 after a failed write | |
1609 | */ | |
1610 | ||
1611 | int | |
1612 | tls_write(const uschar *buff, size_t len) | |
1613 | { | |
17c76198 PP |
1614 | ssize_t outbytes; |
1615 | size_t left = len; | |
1616 | exim_gnutls_state_st *state = current_global_tls_state; | |
059ec3d9 | 1617 | |
17c76198 | 1618 | DEBUG(D_tls) debug_printf("tls_do_write(%p, " SIZE_T_FMT ")\n", buff, left); |
059ec3d9 PH |
1619 | while (left > 0) |
1620 | { | |
17c76198 PP |
1621 | DEBUG(D_tls) debug_printf("gnutls_record_send(SSL, %p, " SIZE_T_FMT ")\n", |
1622 | buff, left); | |
1623 | outbytes = gnutls_record_send(state->session, buff, left); | |
059ec3d9 | 1624 | |
17c76198 | 1625 | DEBUG(D_tls) debug_printf("outbytes=" SSIZE_T_FMT "\n", outbytes); |
059ec3d9 PH |
1626 | if (outbytes < 0) |
1627 | { | |
17c76198 | 1628 | record_io_error(state, outbytes, US"send", NULL); |
059ec3d9 PH |
1629 | return -1; |
1630 | } | |
1631 | if (outbytes == 0) | |
1632 | { | |
17c76198 | 1633 | record_io_error(state, 0, US"send", US"TLS channel closed on write"); |
059ec3d9 PH |
1634 | return -1; |
1635 | } | |
1636 | ||
1637 | left -= outbytes; | |
1638 | buff += outbytes; | |
1639 | } | |
1640 | ||
17c76198 PP |
1641 | if (len > INT_MAX) |
1642 | { | |
1643 | DEBUG(D_tls) | |
1644 | debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT ") than INT_MAX\n", | |
1645 | len); | |
1646 | len = INT_MAX; | |
1647 | } | |
1648 | ||
1649 | return (int) len; | |
059ec3d9 PH |
1650 | } |
1651 | ||
1652 | ||
1653 | ||
17c76198 | 1654 | |
059ec3d9 | 1655 | /************************************************* |
17c76198 | 1656 | * Random number generation * |
059ec3d9 PH |
1657 | *************************************************/ |
1658 | ||
17c76198 PP |
1659 | /* Pseudo-random number generation. The result is not expected to be |
1660 | cryptographically strong but not so weak that someone will shoot themselves | |
1661 | in the foot using it as a nonce in input in some email header scheme or | |
1662 | whatever weirdness they'll twist this into. The result should handle fork() | |
1663 | and avoid repeating sequences. OpenSSL handles that for us. | |
059ec3d9 | 1664 | |
17c76198 PP |
1665 | Arguments: |
1666 | max range maximum | |
1667 | Returns a random number in range [0, max-1] | |
059ec3d9 PH |
1668 | */ |
1669 | ||
17c76198 PP |
1670 | int |
1671 | vaguely_random_number(int max) | |
059ec3d9 | 1672 | { |
17c76198 PP |
1673 | unsigned int r; |
1674 | int i, needed_len; | |
1675 | uschar *p; | |
1676 | uschar smallbuf[sizeof(r)]; | |
1677 | ||
1678 | if (max <= 1) | |
1679 | return 0; | |
1680 | ||
1681 | needed_len = sizeof(r); | |
1682 | /* Don't take 8 times more entropy than needed if int is 8 octets and we were | |
1683 | * asked for a number less than 10. */ | |
1684 | for (r = max, i = 0; r; ++i) | |
1685 | r >>= 1; | |
1686 | i = (i + 7) / 8; | |
1687 | if (i < needed_len) | |
1688 | needed_len = i; | |
1689 | ||
1690 | i = gnutls_rnd(GNUTLS_RND_NONCE, smallbuf, needed_len); | |
1691 | if (i < 0) | |
059ec3d9 | 1692 | { |
17c76198 PP |
1693 | DEBUG(D_all) debug_printf("gnutls_rnd() failed, using fallback.\n"); |
1694 | return vaguely_random_number_fallback(max); | |
1695 | } | |
1696 | r = 0; | |
1697 | for (p = smallbuf; needed_len; --needed_len, ++p) | |
1698 | { | |
1699 | r *= 256; | |
1700 | r += *p; | |
059ec3d9 PH |
1701 | } |
1702 | ||
17c76198 PP |
1703 | /* We don't particularly care about weighted results; if someone wants |
1704 | * smooth distribution and cares enough then they should submit a patch then. */ | |
1705 | return r % max; | |
059ec3d9 PH |
1706 | } |
1707 | ||
36f12725 NM |
1708 | |
1709 | ||
1710 | ||
1711 | /************************************************* | |
1712 | * Report the library versions. * | |
1713 | *************************************************/ | |
1714 | ||
1715 | /* See a description in tls-openssl.c for an explanation of why this exists. | |
1716 | ||
1717 | Arguments: a FILE* to print the results to | |
1718 | Returns: nothing | |
1719 | */ | |
1720 | ||
1721 | void | |
1722 | tls_version_report(FILE *f) | |
1723 | { | |
754a0503 PP |
1724 | fprintf(f, "Library version: GnuTLS: Compile: %s\n" |
1725 | " Runtime: %s\n", | |
1726 | LIBGNUTLS_VERSION, | |
1727 | gnutls_check_version(NULL)); | |
36f12725 NM |
1728 | } |
1729 | ||
059ec3d9 | 1730 | /* End of tls-gnu.c */ |