Commit | Line | Data |
---|---|---|
44bbabb5 PP |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | ||
14a806d6 | 5 | /* Copyright (c) The Exim Maintainers 2019 */ |
f9ba5e22 | 6 | /* Copyright (c) University of Cambridge 1995 - 2018 */ |
44bbabb5 PP |
7 | /* See the file NOTICE for conditions of use and distribution. */ |
8 | ||
df6303fa PP |
9 | /* Copyright (c) Twitter Inc 2012 |
10 | Author: Phil Pennock <pdp@exim.org> */ | |
11 | /* Copyright (c) Phil Pennock 2012 */ | |
44bbabb5 PP |
12 | |
13 | /* Interface to GNU SASL library for generic authentication. */ | |
14 | ||
15 | /* Trade-offs: | |
16 | ||
17 | GNU SASL does not provide authentication data itself, so we have to expose | |
18 | that decision to configuration. For some mechanisms, we need to act much | |
19 | like plaintext. For others, we only need to be able to provide some | |
20 | evaluated data on demand. There's no abstracted way (ie, without hardcoding | |
21 | knowledge of authenticators here) to know which need what properties; we | |
22 | can't query a session or the library for "we will need these for mechanism X". | |
23 | ||
24 | So: we always require server_condition, even if sometimes it will just be | |
25 | set as "yes". We do provide a number of other hooks, which might not make | |
26 | sense in all contexts. For some, we can do checks at init time. | |
27 | */ | |
28 | ||
29 | #include "../exim.h" | |
14a806d6 | 30 | #define CHANNELBIND_HACK |
44bbabb5 PP |
31 | |
32 | #ifndef AUTH_GSASL | |
33 | /* dummy function to satisfy compilers when we link in an "empty" file. */ | |
e1d15f5e JH |
34 | static void dummy(int x); |
35 | static void dummy2(int x) { dummy(x-1); } | |
d9d29e05 | 36 | static void dummy(int x) { dummy2(x-1); } |
44bbabb5 PP |
37 | #else |
38 | ||
39 | #include <gsasl.h> | |
40 | #include "gsasl_exim.h" | |
41 | ||
14a806d6 JH |
42 | #ifdef SUPPORT_I18N |
43 | # include <stringprep.h> | |
44 | #endif | |
45 | ||
46 | ||
44bbabb5 PP |
47 | /* Authenticator-specific options. */ |
48 | /* I did have server_*_condition options for various mechanisms, but since | |
49 | we only ever handle one mechanism at a time, I didn't see the point in keeping | |
50 | that. In case someone sees a point, I've left the condition_check() API | |
51 | alone. */ | |
52 | optionlist auth_gsasl_options[] = { | |
14a806d6 JH |
53 | { "client_authz", opt_stringptr, |
54 | (void *)(offsetof(auth_gsasl_options_block, client_authz)) }, | |
55 | { "client_channelbinding", opt_bool, | |
56 | (void *)(offsetof(auth_gsasl_options_block, client_channelbinding)) }, | |
57 | { "client_password", opt_stringptr, | |
58 | (void *)(offsetof(auth_gsasl_options_block, client_password)) }, | |
59 | { "client_username", opt_stringptr, | |
60 | (void *)(offsetof(auth_gsasl_options_block, client_username)) }, | |
61 | ||
44bbabb5 PP |
62 | { "server_channelbinding", opt_bool, |
63 | (void *)(offsetof(auth_gsasl_options_block, server_channelbinding)) }, | |
64 | { "server_hostname", opt_stringptr, | |
65 | (void *)(offsetof(auth_gsasl_options_block, server_hostname)) }, | |
66 | { "server_mech", opt_stringptr, | |
67 | (void *)(offsetof(auth_gsasl_options_block, server_mech)) }, | |
68 | { "server_password", opt_stringptr, | |
69 | (void *)(offsetof(auth_gsasl_options_block, server_password)) }, | |
70 | { "server_realm", opt_stringptr, | |
71 | (void *)(offsetof(auth_gsasl_options_block, server_realm)) }, | |
72 | { "server_scram_iter", opt_stringptr, | |
73 | (void *)(offsetof(auth_gsasl_options_block, server_scram_iter)) }, | |
74 | { "server_scram_salt", opt_stringptr, | |
75 | (void *)(offsetof(auth_gsasl_options_block, server_scram_salt)) }, | |
76 | { "server_service", opt_stringptr, | |
77 | (void *)(offsetof(auth_gsasl_options_block, server_service)) } | |
78 | }; | |
79 | /* GSASL_SCRAM_SALTED_PASSWORD documented only for client, so not implementing | |
80 | hooks to avoid cleartext passwords in the Exim server. */ | |
81 | ||
82 | int auth_gsasl_options_count = | |
83 | sizeof(auth_gsasl_options)/sizeof(optionlist); | |
84 | ||
85 | /* Defaults for the authenticator-specific options. */ | |
86 | auth_gsasl_options_block auth_gsasl_option_defaults = { | |
14a806d6 JH |
87 | .server_service = US"smtp", |
88 | .server_hostname = US"$primary_hostname", | |
89 | .server_scram_iter = US"4096", | |
90 | /* all others zero/null */ | |
44bbabb5 PP |
91 | }; |
92 | ||
d185889f JH |
93 | |
94 | #ifdef MACRO_PREDEF | |
95 | ||
96 | /* Dummy values */ | |
97 | void auth_gsasl_init(auth_instance *ablock) {} | |
98 | int auth_gsasl_server(auth_instance *ablock, uschar *data) {return 0;} | |
d0858b27 | 99 | int auth_gsasl_client(auth_instance *ablock, smtp_inblock * sx, |
251b9eb4 | 100 | int timeout, uschar *buffer, int buffsize) {return 0;} |
f9df71c0 | 101 | void auth_gsasl_version_report(FILE *f) {} |
d185889f JH |
102 | |
103 | #else /*!MACRO_PREDEF*/ | |
104 | ||
105 | ||
106 | ||
44bbabb5 PP |
107 | /* "Globals" for managing the gsasl interface. */ |
108 | ||
109 | static Gsasl *gsasl_ctx = NULL; | |
110 | static int | |
111 | main_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop); | |
112 | static int | |
113 | server_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock); | |
114 | static int | |
115 | client_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock); | |
116 | ||
117 | static BOOL sasl_error_should_defer = FALSE; | |
118 | static Gsasl_property callback_loop = 0; | |
119 | static BOOL checked_server_condition = FALSE; | |
120 | ||
121 | enum { CURRENTLY_SERVER = 1, CURRENTLY_CLIENT = 2 }; | |
122 | ||
123 | struct callback_exim_state { | |
124 | auth_instance *ablock; | |
125 | int currently; | |
126 | }; | |
127 | ||
128 | ||
129 | /************************************************* | |
130 | * Initialization entry point * | |
131 | *************************************************/ | |
132 | ||
133 | /* Called for each instance, after its options have been read, to | |
134 | enable consistency checks to be done, or anything else that needs | |
135 | to be set up. */ | |
136 | ||
137 | void | |
138 | auth_gsasl_init(auth_instance *ablock) | |
139 | { | |
14a806d6 JH |
140 | static char * once = NULL; |
141 | int rc; | |
d7978c0f JH |
142 | auth_gsasl_options_block *ob = |
143 | (auth_gsasl_options_block *)(ablock->options_block); | |
144 | ||
145 | /* As per existing Cyrus glue, use the authenticator's public name as | |
146 | the default for the mechanism name; we don't handle multiple mechanisms | |
147 | in one authenticator, but the same driver can be used multiple times. */ | |
148 | ||
6a2c32cb | 149 | if (!ob->server_mech) |
d7978c0f JH |
150 | ob->server_mech = string_copy(ablock->public_name); |
151 | ||
152 | /* Can get multiple session contexts from one library context, so just | |
153 | initialise the once. */ | |
6a2c32cb JH |
154 | |
155 | if (!gsasl_ctx) | |
156 | { | |
157 | if ((rc = gsasl_init(&gsasl_ctx)) != GSASL_OK) | |
d7978c0f JH |
158 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " |
159 | "couldn't initialise GNU SASL library: %s (%s)", | |
160 | ablock->name, gsasl_strerror_name(rc), gsasl_strerror(rc)); | |
6a2c32cb | 161 | |
d7978c0f | 162 | gsasl_callback_set(gsasl_ctx, main_callback); |
6a2c32cb | 163 | } |
44bbabb5 | 164 | |
d7978c0f | 165 | /* We don't need this except to log it for debugging. */ |
6a2c32cb | 166 | |
14a806d6 JH |
167 | HDEBUG(D_auth) if (!once) |
168 | { | |
169 | if ((rc = gsasl_server_mechlist(gsasl_ctx, &once)) != GSASL_OK) | |
170 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " | |
171 | "failed to retrieve list of mechanisms: %s (%s)", | |
172 | ablock->name, gsasl_strerror_name(rc), gsasl_strerror(rc)); | |
6a2c32cb | 173 | |
14a806d6 JH |
174 | debug_printf("GNU SASL supports: %s\n", once); |
175 | } | |
44bbabb5 | 176 | |
14a806d6 | 177 | if (!gsasl_client_support_p(gsasl_ctx, CCS ob->server_mech)) |
d7978c0f JH |
178 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " |
179 | "GNU SASL does not support mechanism \"%s\"", | |
180 | ablock->name, ob->server_mech); | |
181 | ||
14a806d6 JH |
182 | ablock->server = TRUE; |
183 | ||
6a2c32cb JH |
184 | if ( !ablock->server_condition |
185 | && ( streqic(ob->server_mech, US"EXTERNAL") | |
186 | || streqic(ob->server_mech, US"ANONYMOUS") | |
187 | || streqic(ob->server_mech, US"PLAIN") | |
188 | || streqic(ob->server_mech, US"LOGIN") | |
189 | ) ) | |
14a806d6 JH |
190 | { |
191 | ablock->server = FALSE; | |
192 | HDEBUG(D_auth) debug_printf("%s authenticator: " | |
193 | "Need server_condition for %s mechanism\n", | |
d7978c0f | 194 | ablock->name, ob->server_mech); |
14a806d6 | 195 | } |
44bbabb5 | 196 | |
d7978c0f JH |
197 | /* This does *not* scale to new SASL mechanisms. Need a better way to ask |
198 | which properties will be needed. */ | |
6a2c32cb JH |
199 | |
200 | if ( !ob->server_realm | |
201 | && streqic(ob->server_mech, US"DIGEST-MD5")) | |
14a806d6 JH |
202 | { |
203 | ablock->server = FALSE; | |
204 | HDEBUG(D_auth) debug_printf("%s authenticator: " | |
205 | "Need server_realm for %s mechanism\n", | |
d7978c0f | 206 | ablock->name, ob->server_mech); |
14a806d6 | 207 | } |
ce52b325 | 208 | |
d7978c0f JH |
209 | /* At present, for mechanisms we don't panic on absence of server_condition; |
210 | need to figure out the most generically correct approach to deciding when | |
211 | it's critical and when it isn't. Eg, for simple validation (PLAIN mechanism, | |
212 | etc) it clearly is critical. | |
d7978c0f | 213 | */ |
6a2c32cb | 214 | |
14a806d6 | 215 | ablock->client = ob->client_username && ob->client_password; |
44bbabb5 PP |
216 | } |
217 | ||
218 | ||
219 | /* GNU SASL uses one top-level callback, registered at library level. | |
220 | We dispatch to client and server functions instead. */ | |
221 | ||
222 | static int | |
223 | main_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop) | |
224 | { | |
d7978c0f JH |
225 | int rc = 0; |
226 | struct callback_exim_state *cb_state = | |
227 | (struct callback_exim_state *)gsasl_session_hook_get(sctx); | |
228 | ||
6a2c32cb | 229 | if (!cb_state) |
d7978c0f | 230 | { |
14a806d6 JH |
231 | HDEBUG(D_auth) debug_printf("gsasl callback (%d) not from our server/client processing\n", prop); |
232 | #ifdef CHANNELBIND_HACK | |
233 | if (prop == GSASL_CB_TLS_UNIQUE) | |
234 | { | |
235 | uschar * s; | |
236 | if ((s = gsasl_callback_hook_get(ctx))) | |
237 | { | |
238 | HDEBUG(D_auth) debug_printf("GSASL_CB_TLS_UNIQUE from ctx hook\n"); | |
239 | gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, CS s); | |
240 | } | |
241 | else | |
242 | { | |
243 | HDEBUG(D_auth) debug_printf("GSASL_CB_TLS_UNIQUE! dummy for now\n"); | |
244 | gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, ""); | |
245 | } | |
246 | return GSASL_OK; | |
247 | } | |
248 | #endif | |
d7978c0f | 249 | return GSASL_NO_CALLBACK; |
44bbabb5 PP |
250 | } |
251 | ||
14a806d6 JH |
252 | HDEBUG(D_auth) |
253 | debug_printf("GNU SASL Callback entered, prop=%d (loop prop=%d)\n", | |
254 | prop, callback_loop); | |
255 | ||
d7978c0f JH |
256 | if (callback_loop > 0) |
257 | { | |
14a806d6 JH |
258 | /* Most likely is that we were asked for property FOO, and to |
259 | expand the string we asked for property BAR to put into an auth | |
260 | variable, but property BAR is not supplied for this mechanism. */ | |
d7978c0f JH |
261 | HDEBUG(D_auth) |
262 | debug_printf("Loop, asked for property %d while handling property %d\n", | |
263 | prop, callback_loop); | |
264 | return GSASL_NO_CALLBACK; | |
44bbabb5 | 265 | } |
d7978c0f | 266 | callback_loop = prop; |
44bbabb5 | 267 | |
d7978c0f JH |
268 | if (cb_state->currently == CURRENTLY_CLIENT) |
269 | rc = client_callback(ctx, sctx, prop, cb_state->ablock); | |
270 | else if (cb_state->currently == CURRENTLY_SERVER) | |
271 | rc = server_callback(ctx, sctx, prop, cb_state->ablock); | |
272 | else | |
273 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " | |
274 | "unhandled callback state, bug in Exim", cb_state->ablock->name); | |
275 | /* NOTREACHED */ | |
44bbabb5 | 276 | |
d7978c0f JH |
277 | callback_loop = 0; |
278 | return rc; | |
44bbabb5 PP |
279 | } |
280 | ||
281 | ||
282 | /************************************************* | |
283 | * Server entry point * | |
284 | *************************************************/ | |
285 | ||
286 | /* For interface, see auths/README */ | |
287 | ||
288 | int | |
289 | auth_gsasl_server(auth_instance *ablock, uschar *initial_data) | |
290 | { | |
d7978c0f JH |
291 | char *tmps; |
292 | char *to_send, *received; | |
293 | Gsasl_session *sctx = NULL; | |
294 | auth_gsasl_options_block *ob = | |
295 | (auth_gsasl_options_block *)(ablock->options_block); | |
296 | struct callback_exim_state cb_state; | |
297 | int rc, auth_result, exim_error, exim_error_override; | |
298 | ||
299 | HDEBUG(D_auth) | |
14a806d6 | 300 | debug_printf("GNU SASL: initialising session for %s, mechanism %s\n", |
d7978c0f JH |
301 | ablock->name, ob->server_mech); |
302 | ||
14a806d6 JH |
303 | #ifndef DISABLE_TLS |
304 | # ifdef CHANNELBIND_HACK | |
305 | /* This is a gross hack to get around the library a) requiring that | |
306 | c-b was already set, at the _start() call, and b) caching a b64'd | |
307 | version of the binding then which it never updates. */ | |
308 | ||
309 | if (tls_in.channelbinding && ob->server_channelbinding) | |
310 | gsasl_callback_hook_set(gsasl_ctx, tls_in.channelbinding); | |
311 | # endif | |
312 | #endif | |
313 | ||
6a2c32cb | 314 | if ((rc = gsasl_server_start(gsasl_ctx, CCS ob->server_mech, &sctx)) != GSASL_OK) |
d7978c0f JH |
315 | { |
316 | auth_defer_msg = string_sprintf("GNU SASL: session start failure: %s (%s)", | |
317 | gsasl_strerror_name(rc), gsasl_strerror(rc)); | |
318 | HDEBUG(D_auth) debug_printf("%s\n", auth_defer_msg); | |
319 | return DEFER; | |
44bbabb5 | 320 | } |
d7978c0f JH |
321 | /* Hereafter: gsasl_finish(sctx) please */ |
322 | ||
d7978c0f JH |
323 | cb_state.ablock = ablock; |
324 | cb_state.currently = CURRENTLY_SERVER; | |
14a806d6 | 325 | gsasl_session_hook_set(sctx, &cb_state); |
d7978c0f JH |
326 | |
327 | tmps = CS expand_string(ob->server_service); | |
328 | gsasl_property_set(sctx, GSASL_SERVICE, tmps); | |
329 | tmps = CS expand_string(ob->server_hostname); | |
330 | gsasl_property_set(sctx, GSASL_HOSTNAME, tmps); | |
331 | if (ob->server_realm) | |
332 | { | |
333 | tmps = CS expand_string(ob->server_realm); | |
334 | if (tmps && *tmps) | |
335 | gsasl_property_set(sctx, GSASL_REALM, tmps); | |
44bbabb5 | 336 | } |
d7978c0f JH |
337 | /* We don't support protection layers. */ |
338 | gsasl_property_set(sctx, GSASL_QOPS, "qop-auth"); | |
6a2c32cb | 339 | |
01603eec | 340 | #ifndef DISABLE_TLS |
b1a32a3c | 341 | if (tls_in.channelbinding) |
d7978c0f JH |
342 | { |
343 | /* Some auth mechanisms can ensure that both sides are talking withing the | |
344 | same security context; for TLS, this means that even if a bad certificate | |
345 | has been accepted, they remain MitM-proof because both sides must be within | |
346 | the same negotiated session; if someone is terminating one session and | |
347 | proxying data on within a second, authentication will fail. | |
348 | ||
349 | We might not have this available, depending upon TLS implementation, | |
350 | ciphersuite, phase of moon ... | |
351 | ||
352 | If we do, it results in extra SASL mechanisms being available; here, | |
353 | Exim's one-mechanism-per-authenticator potentially causes problems. | |
354 | It depends upon how GNU SASL will implement the PLUS variants of GS2 | |
355 | and whether it automatically mandates a switch to the bound PLUS | |
356 | if the data is available. Since default-on, despite being more secure, | |
357 | would then result in mechanism name changes on a library update, we | |
358 | have little choice but to default it off and let the admin choose to | |
359 | enable it. *sigh* | |
360 | */ | |
361 | if (ob->server_channelbinding) | |
362 | { | |
363 | HDEBUG(D_auth) debug_printf("Auth %s: Enabling channel-binding\n", | |
364 | ablock->name); | |
14a806d6 JH |
365 | # ifdef CHANNELBIND_HACK |
366 | gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, CCS tls_in.channelbinding); | |
367 | # endif | |
44bbabb5 | 368 | } |
d7978c0f | 369 | else |
44bbabb5 | 370 | HDEBUG(D_auth) |
d7978c0f JH |
371 | debug_printf("Auth %s: Not enabling channel-binding (data available)\n", |
372 | ablock->name); | |
44bbabb5 | 373 | } |
d7978c0f JH |
374 | else |
375 | HDEBUG(D_auth) | |
376 | debug_printf("Auth %s: no channel-binding data available\n", | |
377 | ablock->name); | |
44bbabb5 PP |
378 | #endif |
379 | ||
d7978c0f JH |
380 | checked_server_condition = FALSE; |
381 | ||
382 | received = CS initial_data; | |
383 | to_send = NULL; | |
384 | exim_error = exim_error_override = OK; | |
385 | ||
386 | do { | |
6a2c32cb | 387 | switch (rc = gsasl_step64(sctx, received, &to_send)) |
d7978c0f JH |
388 | { |
389 | case GSASL_OK: | |
390 | if (!to_send) | |
391 | goto STOP_INTERACTION; | |
392 | break; | |
393 | ||
394 | case GSASL_NEEDS_MORE: | |
395 | break; | |
396 | ||
397 | case GSASL_AUTHENTICATION_ERROR: | |
398 | case GSASL_INTEGRITY_ERROR: | |
399 | case GSASL_NO_AUTHID: | |
400 | case GSASL_NO_ANONYMOUS_TOKEN: | |
401 | case GSASL_NO_AUTHZID: | |
402 | case GSASL_NO_PASSWORD: | |
403 | case GSASL_NO_PASSCODE: | |
404 | case GSASL_NO_PIN: | |
405 | case GSASL_BASE64_ERROR: | |
406 | HDEBUG(D_auth) debug_printf("GNU SASL permanent error: %s (%s)\n", | |
407 | gsasl_strerror_name(rc), gsasl_strerror(rc)); | |
408 | log_write(0, LOG_REJECT, "%s authenticator (%s):\n " | |
409 | "GNU SASL permanent failure: %s (%s)", | |
410 | ablock->name, ob->server_mech, | |
411 | gsasl_strerror_name(rc), gsasl_strerror(rc)); | |
412 | if (rc == GSASL_BASE64_ERROR) | |
413 | exim_error_override = BAD64; | |
414 | goto STOP_INTERACTION; | |
415 | ||
416 | default: | |
417 | auth_defer_msg = string_sprintf("GNU SASL temporary error: %s (%s)", | |
418 | gsasl_strerror_name(rc), gsasl_strerror(rc)); | |
419 | HDEBUG(D_auth) debug_printf("%s\n", auth_defer_msg); | |
420 | exim_error_override = DEFER; | |
421 | goto STOP_INTERACTION; | |
44bbabb5 PP |
422 | } |
423 | ||
6a2c32cb | 424 | if ((rc == GSASL_NEEDS_MORE) || (to_send && *to_send)) |
14a806d6 | 425 | exim_error = auth_get_no64_data(USS &received, US to_send); |
ce52b325 | 426 | |
d7978c0f JH |
427 | if (to_send) |
428 | { | |
429 | free(to_send); | |
430 | to_send = NULL; | |
ce52b325 PP |
431 | } |
432 | ||
d7978c0f JH |
433 | if (exim_error) |
434 | break; /* handles * cancelled check */ | |
44bbabb5 PP |
435 | |
436 | } while (rc == GSASL_NEEDS_MORE); | |
437 | ||
438 | STOP_INTERACTION: | |
d7978c0f | 439 | auth_result = rc; |
44bbabb5 | 440 | |
d7978c0f | 441 | gsasl_finish(sctx); |
44bbabb5 | 442 | |
d7978c0f | 443 | /* Can return: OK DEFER FAIL CANCELLED BAD64 UNEXPECTED */ |
44bbabb5 | 444 | |
d7978c0f JH |
445 | if (exim_error != OK) |
446 | return exim_error; | |
44bbabb5 | 447 | |
d7978c0f JH |
448 | if (auth_result != GSASL_OK) |
449 | { | |
450 | HDEBUG(D_auth) debug_printf("authentication returned %s (%s)\n", | |
451 | gsasl_strerror_name(auth_result), gsasl_strerror(auth_result)); | |
452 | if (exim_error_override != OK) | |
453 | return exim_error_override; /* might be DEFER */ | |
454 | if (sasl_error_should_defer) /* overriding auth failure SASL error */ | |
455 | return DEFER; | |
456 | return FAIL; | |
44bbabb5 PP |
457 | } |
458 | ||
d7978c0f JH |
459 | /* Auth succeeded, check server_condition unless already done in callback */ |
460 | return checked_server_condition ? OK : auth_check_serv_cond(ablock); | |
44bbabb5 PP |
461 | } |
462 | ||
d7978c0f | 463 | |
44bbabb5 PP |
464 | /* returns the GSASL status of expanding the Exim string given */ |
465 | static int | |
466 | condition_check(auth_instance *ablock, uschar *label, uschar *condition_string) | |
467 | { | |
6a2c32cb JH |
468 | int exim_rc = auth_check_some_cond(ablock, label, condition_string, FAIL); |
469 | switch (exim_rc) | |
d7978c0f | 470 | { |
6a2c32cb JH |
471 | case OK: return GSASL_OK; |
472 | case DEFER: sasl_error_should_defer = TRUE; | |
473 | return GSASL_AUTHENTICATION_ERROR; | |
474 | case FAIL: return GSASL_AUTHENTICATION_ERROR; | |
475 | default: log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " | |
476 | "Unhandled return from checking %s: %d", | |
477 | ablock->name, label, exim_rc); | |
44bbabb5 | 478 | } |
d7978c0f | 479 | |
d7978c0f JH |
480 | /* NOTREACHED */ |
481 | return GSASL_AUTHENTICATION_ERROR; | |
44bbabb5 PP |
482 | } |
483 | ||
484 | static int | |
6a2c32cb JH |
485 | server_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, |
486 | auth_instance *ablock) | |
44bbabb5 | 487 | { |
d7978c0f JH |
488 | char *tmps; |
489 | uschar *propval; | |
490 | int cbrc = GSASL_NO_CALLBACK; | |
491 | auth_gsasl_options_block *ob = | |
492 | (auth_gsasl_options_block *)(ablock->options_block); | |
493 | ||
494 | HDEBUG(D_auth) | |
495 | debug_printf("GNU SASL callback %d for %s/%s as server\n", | |
496 | prop, ablock->name, ablock->public_name); | |
497 | ||
498 | for (int i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL; | |
499 | expand_nmax = 0; | |
500 | ||
501 | switch (prop) | |
502 | { | |
503 | case GSASL_VALIDATE_SIMPLE: | |
14a806d6 | 504 | HDEBUG(D_auth) debug_printf(" VALIDATE_SIMPLE\n"); |
d7978c0f | 505 | /* GSASL_AUTHID, GSASL_AUTHZID, and GSASL_PASSWORD */ |
14a806d6 | 506 | propval = US gsasl_property_fast(sctx, GSASL_AUTHID); |
98eb9592 | 507 | auth_vars[0] = expand_nstring[1] = propval ? string_copy(propval) : US""; |
14a806d6 | 508 | propval = US gsasl_property_fast(sctx, GSASL_AUTHZID); |
98eb9592 | 509 | auth_vars[1] = expand_nstring[2] = propval ? string_copy(propval) : US""; |
14a806d6 | 510 | propval = US gsasl_property_fast(sctx, GSASL_PASSWORD); |
98eb9592 | 511 | auth_vars[2] = expand_nstring[3] = propval ? string_copy(propval) : US""; |
d7978c0f JH |
512 | expand_nmax = 3; |
513 | for (int i = 1; i <= 3; ++i) | |
514 | expand_nlength[i] = Ustrlen(expand_nstring[i]); | |
515 | ||
516 | cbrc = condition_check(ablock, US"server_condition", ablock->server_condition); | |
517 | checked_server_condition = TRUE; | |
518 | break; | |
519 | ||
520 | case GSASL_VALIDATE_EXTERNAL: | |
14a806d6 | 521 | HDEBUG(D_auth) debug_printf(" VALIDATE_EXTERNAL\n"); |
6a2c32cb | 522 | if (!ablock->server_condition) |
d7978c0f | 523 | { |
14a806d6 | 524 | HDEBUG(D_auth) debug_printf("No server_condition supplied, to validate EXTERNAL\n"); |
d7978c0f | 525 | cbrc = GSASL_AUTHENTICATION_ERROR; |
44bbabb5 | 526 | break; |
44bbabb5 | 527 | } |
14a806d6 | 528 | propval = US gsasl_property_fast(sctx, GSASL_AUTHZID); |
6a2c32cb | 529 | |
d7978c0f | 530 | /* We always set $auth1, even if only to empty string. */ |
98eb9592 | 531 | auth_vars[0] = expand_nstring[1] = propval ? string_copy(propval) : US""; |
d7978c0f JH |
532 | expand_nlength[1] = Ustrlen(expand_nstring[1]); |
533 | expand_nmax = 1; | |
534 | ||
535 | cbrc = condition_check(ablock, | |
536 | US"server_condition (EXTERNAL)", ablock->server_condition); | |
537 | checked_server_condition = TRUE; | |
538 | break; | |
539 | ||
540 | case GSASL_VALIDATE_ANONYMOUS: | |
14a806d6 | 541 | HDEBUG(D_auth) debug_printf(" VALIDATE_ANONYMOUS\n"); |
6a2c32cb | 542 | if (!ablock->server_condition) |
d7978c0f | 543 | { |
14a806d6 | 544 | HDEBUG(D_auth) debug_printf("No server_condition supplied, to validate ANONYMOUS\n"); |
d7978c0f | 545 | cbrc = GSASL_AUTHENTICATION_ERROR; |
44bbabb5 | 546 | break; |
44bbabb5 | 547 | } |
14a806d6 | 548 | propval = US gsasl_property_fast(sctx, GSASL_ANONYMOUS_TOKEN); |
6a2c32cb | 549 | |
d7978c0f | 550 | /* We always set $auth1, even if only to empty string. */ |
6a2c32cb | 551 | |
98eb9592 | 552 | auth_vars[0] = expand_nstring[1] = propval ? string_copy(propval) : US""; |
d7978c0f JH |
553 | expand_nlength[1] = Ustrlen(expand_nstring[1]); |
554 | expand_nmax = 1; | |
555 | ||
556 | cbrc = condition_check(ablock, | |
557 | US"server_condition (ANONYMOUS)", ablock->server_condition); | |
558 | checked_server_condition = TRUE; | |
559 | break; | |
560 | ||
561 | case GSASL_VALIDATE_GSSAPI: | |
14a806d6 | 562 | HDEBUG(D_auth) debug_printf(" VALIDATE_GSSAPI\n"); |
d7978c0f JH |
563 | /* GSASL_AUTHZID and GSASL_GSSAPI_DISPLAY_NAME |
564 | The display-name is authenticated as part of GSS, the authzid is claimed | |
565 | by the SASL integration after authentication; protected against tampering | |
566 | (if the SASL mechanism supports that, which Kerberos does) but is | |
567 | unverified, same as normal for other mechanisms. | |
6a2c32cb | 568 | First coding, we had these values swapped, but for consistency and prior |
d7978c0f JH |
569 | to the first release of Exim with this authenticator, they've been |
570 | switched to match the ordering of GSASL_VALIDATE_SIMPLE. */ | |
6a2c32cb | 571 | |
14a806d6 | 572 | propval = US gsasl_property_fast(sctx, GSASL_GSSAPI_DISPLAY_NAME); |
98eb9592 | 573 | auth_vars[0] = expand_nstring[1] = propval ? string_copy(propval) : US""; |
14a806d6 | 574 | propval = US gsasl_property_fast(sctx, GSASL_AUTHZID); |
98eb9592 | 575 | auth_vars[1] = expand_nstring[2] = propval ? string_copy(propval) : US""; |
d7978c0f JH |
576 | expand_nmax = 2; |
577 | for (int i = 1; i <= 2; ++i) | |
578 | expand_nlength[i] = Ustrlen(expand_nstring[i]); | |
579 | ||
580 | /* In this one case, it perhaps makes sense to default back open? | |
581 | But for consistency, let's just mandate server_condition here too. */ | |
6a2c32cb | 582 | |
d7978c0f JH |
583 | cbrc = condition_check(ablock, |
584 | US"server_condition (GSSAPI family)", ablock->server_condition); | |
585 | checked_server_condition = TRUE; | |
586 | break; | |
587 | ||
98eb9592 | 588 | case GSASL_SCRAM_ITER: |
14a806d6 | 589 | HDEBUG(D_auth) debug_printf(" SCRAM_ITER\n"); |
98eb9592 JH |
590 | if (ob->server_scram_iter) |
591 | { | |
592 | tmps = CS expand_string(ob->server_scram_iter); | |
593 | gsasl_property_set(sctx, GSASL_SCRAM_ITER, tmps); | |
594 | cbrc = GSASL_OK; | |
595 | } | |
596 | break; | |
597 | ||
598 | case GSASL_SCRAM_SALT: | |
14a806d6 | 599 | HDEBUG(D_auth) debug_printf(" SCRAM_SALT\n"); |
98eb9592 JH |
600 | if (ob->server_scram_iter) |
601 | { | |
602 | tmps = CS expand_string(ob->server_scram_salt); | |
603 | gsasl_property_set(sctx, GSASL_SCRAM_SALT, tmps); | |
604 | cbrc = GSASL_OK; | |
605 | } | |
606 | break; | |
607 | ||
d7978c0f | 608 | case GSASL_PASSWORD: |
14a806d6 | 609 | HDEBUG(D_auth) debug_printf(" PASSWORD\n"); |
d7978c0f JH |
610 | /* DIGEST-MD5: GSASL_AUTHID, GSASL_AUTHZID and GSASL_REALM |
611 | CRAM-MD5: GSASL_AUTHID | |
612 | PLAIN: GSASL_AUTHID and GSASL_AUTHZID | |
613 | LOGIN: GSASL_AUTHID | |
614 | */ | |
615 | if (ob->server_scram_iter) | |
616 | { | |
617 | tmps = CS expand_string(ob->server_scram_iter); | |
618 | gsasl_property_set(sctx, GSASL_SCRAM_ITER, tmps); | |
44bbabb5 | 619 | } |
d7978c0f JH |
620 | if (ob->server_scram_salt) |
621 | { | |
622 | tmps = CS expand_string(ob->server_scram_salt); | |
623 | gsasl_property_set(sctx, GSASL_SCRAM_SALT, tmps); | |
44bbabb5 | 624 | } |
6a2c32cb | 625 | |
d7978c0f JH |
626 | /* Asking for GSASL_AUTHZID calls back into us if we use |
627 | gsasl_property_get(), thus the use of gsasl_property_fast(). | |
628 | Do we really want to hardcode limits per mechanism? What happens when | |
629 | a new mechanism is added to the library. It *shouldn't* result in us | |
630 | needing to add more glue, since avoiding that is a large part of the | |
631 | point of SASL. */ | |
6a2c32cb | 632 | |
14a806d6 | 633 | propval = US gsasl_property_fast(sctx, GSASL_AUTHID); |
98eb9592 | 634 | auth_vars[0] = expand_nstring[1] = propval ? string_copy(propval) : US""; |
14a806d6 | 635 | propval = US gsasl_property_fast(sctx, GSASL_AUTHZID); |
98eb9592 | 636 | auth_vars[1] = expand_nstring[2] = propval ? string_copy(propval) : US""; |
14a806d6 | 637 | propval = US gsasl_property_fast(sctx, GSASL_REALM); |
98eb9592 | 638 | auth_vars[2] = expand_nstring[3] = propval ? string_copy(propval) : US""; |
d7978c0f JH |
639 | expand_nmax = 3; |
640 | for (int i = 1; i <= 3; ++i) | |
641 | expand_nlength[i] = Ustrlen(expand_nstring[i]); | |
642 | ||
6a2c32cb | 643 | if (!(tmps = CS expand_string(ob->server_password))) |
d7978c0f JH |
644 | { |
645 | sasl_error_should_defer = f.expand_string_forcedfail ? FALSE : TRUE; | |
646 | HDEBUG(D_auth) debug_printf("server_password expansion failed, so " | |
647 | "can't tell GNU SASL library the password for %s\n", auth_vars[0]); | |
648 | return GSASL_AUTHENTICATION_ERROR; | |
44bbabb5 | 649 | } |
d7978c0f | 650 | gsasl_property_set(sctx, GSASL_PASSWORD, tmps); |
6a2c32cb | 651 | |
d7978c0f JH |
652 | /* This is inadequate; don't think Exim's store stacks are geared |
653 | for memory wiping, so expanding strings will leave stuff laying around. | |
654 | But no need to compound the problem, so get rid of the one we can. */ | |
6a2c32cb | 655 | |
d7978c0f JH |
656 | memset(tmps, '\0', strlen(tmps)); |
657 | cbrc = GSASL_OK; | |
658 | break; | |
659 | ||
660 | default: | |
14a806d6 | 661 | HDEBUG(D_auth) debug_printf(" Unrecognised callback: %d\n", prop); |
d7978c0f | 662 | cbrc = GSASL_NO_CALLBACK; |
44bbabb5 PP |
663 | } |
664 | ||
d7978c0f JH |
665 | HDEBUG(D_auth) debug_printf("Returning %s (%s)\n", |
666 | gsasl_strerror_name(cbrc), gsasl_strerror(cbrc)); | |
44bbabb5 | 667 | |
d7978c0f | 668 | return cbrc; |
44bbabb5 PP |
669 | } |
670 | ||
671 | ||
14a806d6 JH |
672 | /******************************************************************************/ |
673 | ||
674 | #define PROP_OPTIONAL BIT(0) | |
675 | #define PROP_STRINGPREP BIT(1) | |
676 | ||
677 | ||
678 | static BOOL | |
679 | client_prop(Gsasl_session * sctx, Gsasl_property propnum, uschar * val, | |
680 | const uschar * why, unsigned flags, uschar * buffer, int buffsize) | |
681 | { | |
682 | uschar * s, * t; | |
683 | int rc; | |
684 | ||
685 | if (flags & PROP_OPTIONAL && !val) return TRUE; | |
686 | if (!(s = expand_string(val)) || !(flags & PROP_OPTIONAL) && !*s) | |
687 | { | |
688 | string_format(buffer, buffsize, "%s", expand_string_message); | |
689 | return FALSE; | |
690 | } | |
691 | if (!*s) return TRUE; | |
692 | ||
693 | #ifdef SUPPORT_I18N | |
694 | if (flags & PROP_STRINGPREP) | |
695 | { | |
696 | if (gsasl_saslprep(CCS s, 0, CSS &t, &rc) != GSASL_OK) | |
697 | { | |
698 | string_format(buffer, buffsize, "Bad result from saslprep(%s): %s\n", | |
699 | why, stringprep_strerror(rc)); | |
700 | HDEBUG(D_auth) debug_printf("%s\n", buffer); | |
701 | return FALSE; | |
702 | } | |
703 | gsasl_property_set(sctx, propnum, CS t); | |
704 | ||
705 | free(t); | |
706 | } | |
707 | else | |
708 | #endif | |
709 | gsasl_property_set(sctx, propnum, CS s); | |
710 | ||
711 | return TRUE; | |
712 | } | |
713 | ||
44bbabb5 PP |
714 | /************************************************* |
715 | * Client entry point * | |
716 | *************************************************/ | |
717 | ||
718 | /* For interface, see auths/README */ | |
719 | ||
720 | int | |
721 | auth_gsasl_client( | |
d0858b27 JH |
722 | auth_instance *ablock, /* authenticator block */ |
723 | smtp_inblock * sx, /* connection */ | |
724 | int timeout, /* command timeout */ | |
725 | uschar *buffer, /* buffer for reading response */ | |
726 | int buffsize) /* size of buffer */ | |
44bbabb5 | 727 | { |
14a806d6 JH |
728 | auth_gsasl_options_block *ob = |
729 | (auth_gsasl_options_block *)(ablock->options_block); | |
730 | Gsasl_session * sctx = NULL; | |
731 | struct callback_exim_state cb_state; | |
732 | uschar * s; | |
733 | BOOL initial = TRUE, do_stringprep; | |
734 | int rc, yield = FAIL, flags; | |
735 | ||
d7978c0f | 736 | HDEBUG(D_auth) |
14a806d6 JH |
737 | debug_printf("GNU SASL: initialising session for %s, mechanism %s\n", |
738 | ablock->name, ob->server_mech); | |
739 | ||
740 | *buffer = 0; | |
741 | ||
742 | #ifndef DISABLE_TLS | |
743 | /* This is a gross hack to get around the library a) requiring that | |
744 | c-b was already set, at the _start() call, and b) caching a b64'd | |
745 | version of the binding then which it never updates. */ | |
746 | ||
747 | if (tls_out.channelbinding) | |
748 | if (ob->client_channelbinding) | |
749 | gsasl_callback_hook_set(gsasl_ctx, tls_out.channelbinding); | |
750 | #endif | |
751 | ||
752 | if ((rc = gsasl_client_start(gsasl_ctx, CCS ob->server_mech, &sctx)) != GSASL_OK) | |
753 | { | |
754 | string_format(buffer, buffsize, "GNU SASL: session start failure: %s (%s)", | |
755 | gsasl_strerror_name(rc), gsasl_strerror(rc)); | |
756 | HDEBUG(D_auth) debug_printf("%s\n", buffer); | |
757 | return ERROR; | |
758 | } | |
759 | ||
760 | cb_state.ablock = ablock; | |
761 | cb_state.currently = CURRENTLY_CLIENT; | |
762 | gsasl_session_hook_set(sctx, &cb_state); | |
763 | ||
764 | /* Set properties */ | |
765 | ||
766 | flags = Ustrncmp(ob->server_mech, "SCRAM-", 5) == 0 ? PROP_STRINGPREP : 0; | |
767 | ||
768 | if ( !client_prop(sctx, GSASL_PASSWORD, ob->client_password, US"password", | |
769 | flags, buffer, buffsize) | |
770 | || !client_prop(sctx, GSASL_AUTHID, ob->client_username, US"username", | |
771 | flags, buffer, buffsize) | |
772 | || !client_prop(sctx, GSASL_AUTHZID, ob->client_authz, US"authz", | |
773 | flags | PROP_OPTIONAL, buffer, buffsize) | |
774 | ) | |
775 | return ERROR; | |
776 | ||
777 | #ifndef DISABLE_TLS | |
778 | if (tls_out.channelbinding) | |
779 | if (ob->client_channelbinding) | |
780 | { | |
781 | HDEBUG(D_auth) debug_printf("Auth %s: Enabling channel-binding\n", | |
782 | ablock->name); | |
783 | # ifdef CHANNELBIND_HACK | |
784 | gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, CCS tls_out.channelbinding); | |
785 | # endif | |
786 | } | |
787 | else | |
788 | HDEBUG(D_auth) | |
789 | debug_printf("Auth %s: Not enabling channel-binding (data available)\n", | |
790 | ablock->name); | |
791 | #endif | |
792 | ||
793 | /* Run the SASL conversation with the server */ | |
794 | ||
795 | for(s = NULL; ;) | |
796 | { | |
797 | uschar * outstr; | |
798 | BOOL fail; | |
799 | ||
800 | rc = gsasl_step64(sctx, CS s, CSS &outstr); | |
801 | ||
802 | fail = initial | |
803 | ? smtp_write_command(sx, SCMD_FLUSH, | |
804 | outstr ? "AUTH %s %s\r\n" : "AUTH %s\r\n", | |
805 | ablock->public_name, outstr) <= 0 | |
806 | : outstr | |
807 | ? smtp_write_command(sx, SCMD_FLUSH, "%s\r\n", outstr) <= 0 | |
808 | : FALSE; | |
809 | if (outstr && *outstr) free(outstr); | |
810 | if (fail) | |
811 | { | |
812 | yield = FAIL_SEND; | |
813 | goto done; | |
814 | } | |
815 | initial = FALSE; | |
816 | ||
817 | if (rc != GSASL_NEEDS_MORE) | |
818 | { | |
819 | if (rc != GSASL_OK) | |
820 | { | |
821 | string_format(buffer, buffsize, "gsasl: %s", gsasl_strerror(rc)); | |
822 | break; | |
823 | } | |
824 | ||
825 | /* expecting a final 2xx from the server, accepting the AUTH */ | |
826 | ||
827 | if (smtp_read_response(sx, buffer, buffsize, '2', timeout)) | |
828 | yield = OK; | |
829 | break; /* from SASL sequence loop */ | |
830 | } | |
831 | ||
832 | /* 2xx or 3xx response is acceptable. If 2xx, no further input */ | |
833 | ||
834 | if (!smtp_read_response(sx, buffer, buffsize, '3', timeout)) | |
835 | if (errno == 0 && buffer[0] == '2') | |
836 | buffer[4] = '\0'; | |
837 | else | |
838 | { | |
839 | yield = FAIL; | |
840 | goto done; | |
841 | } | |
842 | s = buffer + 4; | |
843 | } | |
844 | ||
845 | done: | |
846 | gsasl_finish(sctx); | |
847 | return yield; | |
44bbabb5 PP |
848 | } |
849 | ||
850 | static int | |
851 | client_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock) | |
852 | { | |
14a806d6 JH |
853 | HDEBUG(D_auth) debug_printf("GNU SASL callback %d for %s/%s as client\n", |
854 | prop, ablock->name, ablock->public_name); | |
855 | switch (prop) | |
856 | { | |
857 | case GSASL_AUTHZID: | |
858 | HDEBUG(D_auth) debug_printf(" inquired for AUTHZID; not providing one\n"); | |
859 | break; | |
860 | case GSASL_SCRAM_SALTED_PASSWORD: | |
861 | HDEBUG(D_auth) | |
862 | debug_printf(" inquired for SCRAM_SALTED_PASSWORD; not providing one\n"); | |
863 | break; | |
864 | case GSASL_CB_TLS_UNIQUE: | |
865 | HDEBUG(D_auth) | |
866 | debug_printf(" inquired for CB_TLS_UNIQUE, filling in\n"); | |
867 | gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, CCS tls_out.channelbinding); | |
868 | break; | |
869 | } | |
870 | return GSASL_NO_CALLBACK; | |
44bbabb5 PP |
871 | } |
872 | ||
873 | /************************************************* | |
874 | * Diagnostic API * | |
875 | *************************************************/ | |
876 | ||
877 | void | |
878 | auth_gsasl_version_report(FILE *f) | |
879 | { | |
d7978c0f JH |
880 | const char *runtime; |
881 | runtime = gsasl_check_version(NULL); | |
882 | fprintf(f, "Library version: GNU SASL: Compile: %s\n" | |
883 | " Runtime: %s\n", | |
884 | GSASL_VERSION, runtime); | |
44bbabb5 PP |
885 | } |
886 | ||
d185889f | 887 | #endif /*!MACRO_PREDEF*/ |
44bbabb5 PP |
888 | #endif /* AUTH_GSASL */ |
889 | ||
890 | /* End of gsasl_exim.c */ |