1 /* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
5 * Copyright (C) 2009 by the Massachusetts Institute of Technology.
8 * Export of this software from the United States of America may
9 * require a specific license from the United States Government.
10 * It is the responsibility of any person or organization contemplating
11 * export to obtain such a license before exporting.
13 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
14 * distribute this software and its documentation for any purpose and
15 * without fee is hereby granted, provided that the above copyright
16 * notice appear in all copies and that both that copyright notice and
17 * this permission notice appear in supporting documentation, and that
18 * the name of M.I.T. not be used in advertising or publicity pertaining
19 * to distribution of the software without specific, written prior
20 * permission. Furthermore if you modify this software you must label
21 * your software as modified software and not distribute it in such a
22 * fashion that it might be confused with the original M.I.T. software.
23 * M.I.T. makes no representations about the suitability of
24 * this software for any purpose. It is provided "as is" without express
25 * or implied warranty.
34 * It is possible to support sending a request that includes both a
35 * FAST and normal version. This would complicate the
36 * pre-authentication logic significantly. You would need to maintain
37 * two contexts, one for FAST and one for normal use. In adition, you
38 * would need to manage the security issues surrounding downgrades.
39 * However trying FAST at all requires an armor key. Generally in
40 * obtaining the armor key, the client learns enough to know that FAST
41 * is supported. If not, the client can see FAST in the
42 * preauth_required error's padata and retry with FAST. So, this
43 * implementation does not support FAST+normal.
45 * We store the outer version of the request to use . The caller
46 * stores the inner version. We handle the encoding of the request
47 * body (and request) and provide encoded request bodies for the
48 * caller to use as these may be used for checksums. In the AS case
49 * we also evaluate whether to continue a conversation as one of the
50 * important questions there is the presence of a cookie.
53 #include "int-proto.h"
56 static krb5_error_code
57 fast_armor_ap_request(krb5_context context,
58 struct krb5int_fast_request_state *state,
59 krb5_ccache ccache, krb5_data *target_realm)
61 krb5_error_code retval = 0;
62 krb5_creds creds, *out_creds = NULL;
63 krb5_auth_context authcontext = NULL;
64 krb5_data encoded_authenticator;
65 krb5_fast_armor *armor = NULL;
66 krb5_keyblock *subkey = NULL, *armor_key = NULL;
67 encoded_authenticator.data = NULL;
68 memset(&creds, 0, sizeof(creds));
69 retval = krb5_tgtname(context, target_realm, target_realm, &creds.server);
71 retval = krb5_cc_get_principal(context, ccache, &creds.client);
73 retval = krb5_get_credentials(context, 0, ccache, &creds, &out_creds);
75 retval = krb5_mk_req_extended(context, &authcontext, AP_OPTS_USE_SUBKEY, NULL /*data*/,
76 out_creds, &encoded_authenticator);
78 retval = krb5_auth_con_getsendsubkey(context, authcontext, &subkey);
80 retval = krb5_c_fx_cf2_simple(context, subkey, "subkeyarmor",
81 &out_creds->keyblock, "ticketarmor", &armor_key);
83 armor = calloc(1, sizeof(krb5_fast_armor));
88 armor->armor_type = KRB5_FAST_ARMOR_AP_REQUEST;
89 armor->armor_value = encoded_authenticator;
90 encoded_authenticator.data = NULL;
91 encoded_authenticator.length = 0;
94 state->armor_key = armor_key;
97 krb5_free_keyblock(context, armor_key);
98 krb5_free_keyblock(context, subkey);
100 krb5_free_creds(context, out_creds);
101 krb5_free_cred_contents(context, &creds);
102 if (encoded_authenticator.data)
103 krb5_free_data_contents(context, &encoded_authenticator);
104 krb5_auth_con_free(context, authcontext);
109 krb5int_fast_prep_req_body(krb5_context context, struct krb5int_fast_request_state *state,
110 krb5_kdc_req *request, krb5_data **encoded_request_body)
112 krb5_error_code retval = 0;
113 krb5_data *local_encoded_request_body = NULL;
114 assert(state != NULL);
115 *encoded_request_body = NULL;
116 if (state->armor_key == NULL) {
117 return encode_krb5_kdc_req_body(request, encoded_request_body);
119 state->fast_outer_request = *request;
120 state->fast_outer_request.padata = NULL;
122 retval = encode_krb5_kdc_req_body(&state->fast_outer_request,
123 &local_encoded_request_body);
125 *encoded_request_body = local_encoded_request_body;
126 local_encoded_request_body = NULL;
128 if (local_encoded_request_body != NULL)
129 krb5_free_data(context, local_encoded_request_body);
134 krb5int_fast_as_armor(krb5_context context,
135 struct krb5int_fast_request_state *state,
136 krb5_gic_opt_ext *opte,
137 krb5_kdc_req *request)
139 krb5_error_code retval = 0;
140 krb5_ccache ccache = NULL;
141 krb5_clear_error_message(context);
142 if (opte->opt_private->fast_ccache_name) {
143 retval = krb5_cc_resolve(context, opte->opt_private->fast_ccache_name,
146 retval = fast_armor_ap_request(context, state, ccache,
147 krb5_princ_realm(context, request->server));
150 errmsg = krb5_get_error_message(context, retval);
152 krb5_set_error_message(context, retval, "%s constructing AP-REQ armor", errmsg);
153 krb5_free_error_message(context, errmsg);
158 krb5_cc_close(context, ccache);
164 krb5int_fast_prep_req(krb5_context context,
165 struct krb5int_fast_request_state *state,
166 krb5_kdc_req *request,
167 const krb5_data *to_be_checksummed,
168 kdc_req_encoder_proc encoder,
169 krb5_data **encoded_request)
171 krb5_error_code retval = 0;
172 krb5_pa_data *pa_array[2];
174 krb5_fast_req fast_req;
175 krb5_fast_armored_req *armored_req = NULL;
176 krb5_data *encoded_fast_req = NULL;
177 krb5_data *encoded_armored_req = NULL;
178 krb5_data *local_encoded_result = NULL;
179 krb5_cksumtype cksumtype;
180 krb5_data random_data;
184 assert(state != NULL);
185 assert(state->fast_outer_request.padata == NULL);
186 memset(pa_array, 0, sizeof pa_array);
187 if (state->armor_key == NULL) {
188 return encoder(request, encoded_request);
190 /* Fill in a fresh random nonce for each inner request*/
191 random_data.length = 4;
192 random_data.data = (char *)random_buf;
193 retval = krb5_c_random_make_octets(context, &random_data);
195 request->nonce = 0x7fffffff & load_32_n(random_buf);
196 state->nonce = request->nonce;
198 fast_req.req_body = request;
199 if (fast_req.req_body->padata == NULL) {
200 fast_req.req_body->padata = calloc(1, sizeof(krb5_pa_data *));
201 if (fast_req.req_body->padata == NULL)
204 fast_req.fast_options = state->fast_options;
206 retval = encode_krb5_fast_req(&fast_req, &encoded_fast_req);
208 armored_req = calloc(1, sizeof(krb5_fast_armored_req));
209 if (armored_req == NULL)
213 armored_req->armor = state->armor;
215 retval = krb5int_c_mandatory_cksumtype(context, state->armor_key->enctype,
218 retval = krb5_c_make_checksum(context, cksumtype, state->armor_key,
219 KRB5_KEYUSAGE_FAST_REQ_CHKSUM, to_be_checksummed,
220 &armored_req->req_checksum);
222 retval = krb5_encrypt_helper(context, state->armor_key,
223 KRB5_KEYUSAGE_FAST_ENC, encoded_fast_req,
224 &armored_req->enc_part);
226 retval = encode_krb5_pa_fx_fast_request(armored_req, &encoded_armored_req);
228 pa[0].pa_type = KRB5_PADATA_FX_FAST;
229 pa[0].contents = (unsigned char *) encoded_armored_req->data;
230 pa[0].length = encoded_armored_req->length;
231 pa_array[0] = &pa[0];
233 state->fast_outer_request.padata = pa_array;
235 retval = encoder(&state->fast_outer_request, &local_encoded_result);
237 *encoded_request = local_encoded_result;
238 local_encoded_result = NULL;
240 if (encoded_armored_req)
241 krb5_free_data(context, encoded_armored_req);
243 armored_req->armor = NULL; /*owned by state*/
244 krb5_free_fast_armored_req(context, armored_req);
246 if (encoded_fast_req)
247 krb5_free_data(context, encoded_fast_req);
248 if (local_encoded_result)
249 krb5_free_data(context, local_encoded_result);
250 state->fast_outer_request.padata = NULL;
254 static krb5_error_code
255 decrypt_fast_reply(krb5_context context,
256 struct krb5int_fast_request_state *state,
257 krb5_pa_data **in_padata,
258 krb5_fast_response **response)
260 krb5_error_code retval = 0;
262 krb5_enc_data *encrypted_response = NULL;
263 krb5_pa_data *fx_reply = NULL;
264 krb5_fast_response *local_resp = NULL;
265 assert(state != NULL);
266 assert(state->armor_key);
267 fx_reply = krb5int_find_pa_data(context, in_padata, KRB5_PADATA_FX_FAST);
268 if (fx_reply == NULL)
269 retval = KRB5_ERR_FAST_REQUIRED;
271 scratch.data = (char *) fx_reply->contents;
272 scratch.length = fx_reply->length;
273 retval = decode_krb5_pa_fx_fast_reply(&scratch, &encrypted_response);
277 scratch.data = malloc(encrypted_response->ciphertext.length);
278 if (scratch.data == NULL)
280 scratch.length = encrypted_response->ciphertext.length;
283 retval = krb5_c_decrypt(context, state->armor_key,
284 KRB5_KEYUSAGE_FAST_REP, NULL,
285 encrypted_response, &scratch);
288 errmsg = krb5_get_error_message(context, retval);
289 krb5_set_error_message(context, retval, "%s while decrypting FAST reply", errmsg);
290 krb5_free_error_message(context, errmsg);
293 retval = decode_krb5_fast_response(&scratch, &local_resp);
295 if (local_resp->nonce != state->nonce) {
296 retval = KRB5_KDCREP_MODIFIED;
297 krb5_set_error_message(context, retval, "nonce modified in FAST response: KDC response modified");
301 *response = local_resp;
306 if (encrypted_response)
307 krb5_free_enc_data(context, encrypted_response);
309 krb5_free_fast_response(context, local_resp);
314 * FAST separates two concepts: the set of padata we're using to
315 * decide what pre-auth mechanisms to use and the set of padata we're
316 * making available to mechanisms in order for them to respond to an
317 * error. The plugin interface in March 2009 does not permit
318 * separating these concepts for the plugins. This function makes
319 * both available for future revisions to the plugin interface. It
320 * also re-encodes the padata from the current error as a encoded
321 * typed-data and puts that in the e_data field. That will allow
322 * existing plugins with the old interface to find the error data.
323 * The output parameter out_padata contains the padata from the error
324 * whenever padata is available (all the time with fast).
327 krb5int_fast_process_error(krb5_context context,
328 struct krb5int_fast_request_state *state,
329 krb5_error **err_replyptr,
330 krb5_pa_data ***out_padata,
333 krb5_error_code retval = 0;
334 krb5_error *err_reply = *err_replyptr;
337 if (state->armor_key) {
338 krb5_pa_data *fx_error_pa;
339 krb5_pa_data **result = NULL;
340 krb5_data scratch, *encoded_td = NULL;
341 krb5_error *fx_error = NULL;
342 krb5_fast_response *fast_response = NULL;
343 retval = decode_krb5_padata_sequence(&err_reply->e_data, &result);
345 retval = decrypt_fast_reply(context, state, result, &fast_response);
347 /*This can happen if the KDC does not understand FAST. We
348 * don't expect that, but treating it as the fatal error
349 * indicated by the KDC seems reasonable.
352 krb5_free_pa_data(context, result);
355 krb5_free_pa_data(context, result);
358 fx_error_pa = krb5int_find_pa_data(context, fast_response->padata, KRB5_PADATA_FX_ERROR);
359 if (fx_error_pa == NULL) {
360 krb5_set_error_message(context, KRB5KDC_ERR_PREAUTH_FAILED, "Expecting FX_ERROR pa-data inside FAST container");
361 retval = KRB5KDC_ERR_PREAUTH_FAILED;
365 scratch.data = (char *) fx_error_pa->contents;
366 scratch.length = fx_error_pa->length;
367 retval = decode_krb5_error(&scratch, &fx_error);
370 * krb5_pa_data and krb5_typed_data are safe to cast between:
371 * they have the same type fields in the same order.
372 * (krb5_preauthtype is a krb5_int32). If krb5_typed_data is
373 * ever changed then this will need to be a copy not a cast.
376 retval = encode_krb5_typed_data( (krb5_typed_data **) fast_response->padata,
379 fx_error->e_data = *encoded_td;
380 free(encoded_td); /*contents owned by fx_error*/
382 krb5_free_error(context, err_reply);
383 *err_replyptr = fx_error;
385 *out_padata = fast_response->padata;
386 fast_response->padata = NULL;
388 * If there is more than the fx_error padata, then we want
389 * to retry the error if a cookie is present
391 *retry = (*out_padata)[1] != NULL;
392 if (krb5int_find_pa_data(context, *out_padata, KRB5_PADATA_FX_COOKIE) == NULL)
396 krb5_free_error(context, fx_error);
397 krb5_free_fast_response(context, fast_response);
398 } else { /*not FAST*/
399 *retry = (err_reply->e_data.length > 0);
400 if ((err_reply->error == KDC_ERR_PREAUTH_REQUIRED
401 ||err_reply->error == KDC_ERR_PREAUTH_FAILED) && err_reply->e_data.length) {
402 krb5_pa_data **result = NULL;
403 retval = decode_krb5_padata_sequence(&err_reply->e_data, &result);
406 *out_padata = result;
410 krb5_free_pa_data(context, result);
411 krb5_set_error_message(context, retval,
412 "Error decoding padata in error reply");
421 krb5int_fast_process_response(krb5_context context,
422 struct krb5int_fast_request_state *state,
424 krb5_keyblock **strengthen_key)
426 krb5_error_code retval = 0;
427 krb5_fast_response *fast_response = NULL;
428 krb5_data *encoded_ticket = NULL;
429 krb5_boolean cksum_valid;
430 krb5_clear_error_message(context);
431 *strengthen_key = NULL;
432 if (state->armor_key == 0)
434 retval = decrypt_fast_reply(context, state, resp->padata,
437 if (fast_response->finished == 0) {
438 retval = KRB5_KDCREP_MODIFIED;
439 krb5_set_error_message(context, retval, "FAST response missing finish message in KDC reply");
443 retval = encode_krb5_ticket(resp->ticket, &encoded_ticket);
445 retval = krb5_c_verify_checksum(context, state->armor_key,
446 KRB5_KEYUSAGE_FAST_FINISHED,
448 &fast_response->finished->ticket_checksum,
450 if (retval == 0 && cksum_valid == 0) {
451 retval = KRB5_KDCREP_MODIFIED;
452 krb5_set_error_message(context, retval, "ticket modified in KDC reply");
455 krb5_free_principal(context, resp->client);
456 resp->client = fast_response->finished->client;
457 fast_response->finished->client = NULL;
458 *strengthen_key = fast_response->strengthen_key;
459 fast_response->strengthen_key = NULL;
460 krb5_free_pa_data(context, resp->padata);
461 resp->padata = fast_response->padata;
462 fast_response->padata = NULL;
465 krb5_free_fast_response(context, fast_response);
467 krb5_free_data(context, encoded_ticket);
472 krb5int_fast_reply_key(krb5_context context,
473 krb5_keyblock *strengthen_key,
474 krb5_keyblock *existing_key,
475 krb5_keyblock *out_key)
477 krb5_keyblock *key = NULL;
478 krb5_error_code retval = 0;
479 krb5_free_keyblock_contents(context, out_key);
480 if (strengthen_key) {
481 retval = krb5_c_fx_cf2_simple(context, strengthen_key,
482 "strengthenkey", existing_key, "replykey", &key);
488 retval = krb5_copy_keyblock_contents(context, existing_key, out_key);
495 krb5int_fast_make_state( krb5_context context, struct krb5int_fast_request_state **state)
497 struct krb5int_fast_request_state *local_state ;
498 local_state = malloc(sizeof *local_state);
499 if (local_state == NULL)
501 memset(local_state, 0, sizeof(*local_state));
502 *state = local_state;
507 krb5int_fast_free_state( krb5_context context, struct krb5int_fast_request_state *state)
509 /*We are responsible for none of the store in the fast_outer_req*/
510 krb5_free_keyblock(context, state->armor_key);
511 krb5_free_fast_armor(context, state->armor);
516 krb5int_find_pa_data(krb5_context context, krb5_pa_data *const *padata,
517 krb5_preauthtype pa_type)
519 krb5_pa_data * const *tmppa;
524 for (tmppa = padata; *tmppa != NULL; tmppa++) {
525 if ((*tmppa)->pa_type == pa_type)