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_principal target_principal)
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 creds.server = target_principal;
70 retval = krb5_cc_get_principal(context, ccache, &creds.client);
72 retval = krb5_get_credentials(context, 0, ccache, &creds, &out_creds);
74 retval = krb5_mk_req_extended(context, &authcontext, AP_OPTS_USE_SUBKEY, NULL /*data*/,
75 out_creds, &encoded_authenticator);
77 retval = krb5_auth_con_getsendsubkey(context, authcontext, &subkey);
79 retval = krb5_c_fx_cf2_simple(context, subkey, "subkeyarmor",
80 &out_creds->keyblock, "ticketarmor", &armor_key);
82 armor = calloc(1, sizeof(krb5_fast_armor));
87 armor->armor_type = KRB5_FAST_ARMOR_AP_REQUEST;
88 armor->armor_value = encoded_authenticator;
89 encoded_authenticator.data = NULL;
90 encoded_authenticator.length = 0;
93 state->armor_key = armor_key;
96 krb5_free_keyblock(context, armor_key);
97 krb5_free_keyblock(context, subkey);
99 krb5_free_creds(context, out_creds);
100 /* target_principal is owned by caller. */
102 krb5_free_cred_contents(context, &creds);
103 if (encoded_authenticator.data)
104 krb5_free_data_contents(context, &encoded_authenticator);
105 krb5_auth_con_free(context, authcontext);
110 krb5int_fast_prep_req_body(krb5_context context, struct krb5int_fast_request_state *state,
111 krb5_kdc_req *request, krb5_data **encoded_request_body)
113 krb5_error_code retval = 0;
114 krb5_data *local_encoded_request_body = NULL;
115 assert(state != NULL);
116 *encoded_request_body = NULL;
117 if (state->armor_key == NULL) {
118 return encode_krb5_kdc_req_body(request, encoded_request_body);
120 state->fast_outer_request = *request;
121 state->fast_outer_request.padata = NULL;
123 retval = encode_krb5_kdc_req_body(&state->fast_outer_request,
124 &local_encoded_request_body);
126 *encoded_request_body = local_encoded_request_body;
127 local_encoded_request_body = NULL;
129 if (local_encoded_request_body != NULL)
130 krb5_free_data(context, local_encoded_request_body);
135 krb5int_fast_as_armor(krb5_context context,
136 struct krb5int_fast_request_state *state,
137 krb5_gic_opt_ext *opte,
138 krb5_kdc_req *request)
140 krb5_error_code retval = 0;
141 krb5_ccache ccache = NULL;
142 krb5_principal target_principal = NULL;
143 krb5_data *target_realm;
144 krb5_clear_error_message(context);
145 target_realm = krb5_princ_realm(context, request->server);
146 if (opte->opt_private->fast_ccache_name) {
147 state->fast_state_flags |= KRB5INT_FAST_ARMOR_AVAIL;
148 retval = krb5_cc_resolve(context, opte->opt_private->fast_ccache_name,
151 retval = krb5_tgtname(context, target_realm, target_realm,
155 krb5_data config_data;
156 config_data.data = NULL;
157 retval = krb5_cc_get_config(context, ccache, target_principal,
158 KRB5_CONF_FAST_AVAIL, &config_data);
159 if ((retval == 0) && config_data.data )
160 state->fast_state_flags |= KRB5INT_FAST_DO_FAST;
161 krb5_free_data_contents(context, &config_data);
164 if (opte->opt_private->fast_flags& KRB5_FAST_REQUIRED)
165 state->fast_state_flags |= KRB5INT_FAST_DO_FAST;
166 if (retval == 0 && (state->fast_state_flags & KRB5INT_FAST_DO_FAST)) {
167 retval = fast_armor_ap_request(context, state, ccache,
172 errmsg = krb5_get_error_message(context, retval);
174 krb5_set_error_message(context, retval, "%s constructing AP-REQ armor", errmsg);
175 krb5_free_error_message(context, errmsg);
180 krb5_cc_close(context, ccache);
181 if (target_principal)
182 krb5_free_principal(context, target_principal);
188 krb5int_fast_prep_req(krb5_context context,
189 struct krb5int_fast_request_state *state,
190 krb5_kdc_req *request,
191 const krb5_data *to_be_checksummed,
192 kdc_req_encoder_proc encoder,
193 krb5_data **encoded_request)
195 krb5_error_code retval = 0;
196 krb5_pa_data *pa_array[2];
198 krb5_fast_req fast_req;
199 krb5_fast_armored_req *armored_req = NULL;
200 krb5_data *encoded_fast_req = NULL;
201 krb5_data *encoded_armored_req = NULL;
202 krb5_data *local_encoded_result = NULL;
203 krb5_cksumtype cksumtype;
204 krb5_data random_data;
208 assert(state != NULL);
209 assert(state->fast_outer_request.padata == NULL);
210 memset(pa_array, 0, sizeof pa_array);
211 if (state->armor_key == NULL) {
212 return encoder(request, encoded_request);
214 /* Fill in a fresh random nonce for each inner request*/
215 random_data.length = 4;
216 random_data.data = (char *)random_buf;
217 retval = krb5_c_random_make_octets(context, &random_data);
219 request->nonce = 0x7fffffff & load_32_n(random_buf);
220 state->nonce = request->nonce;
222 fast_req.req_body = request;
223 if (fast_req.req_body->padata == NULL) {
224 fast_req.req_body->padata = calloc(1, sizeof(krb5_pa_data *));
225 if (fast_req.req_body->padata == NULL)
228 fast_req.fast_options = state->fast_options;
230 retval = encode_krb5_fast_req(&fast_req, &encoded_fast_req);
232 armored_req = calloc(1, sizeof(krb5_fast_armored_req));
233 if (armored_req == NULL)
237 armored_req->armor = state->armor;
239 retval = krb5int_c_mandatory_cksumtype(context, state->armor_key->enctype,
242 retval = krb5_c_make_checksum(context, cksumtype, state->armor_key,
243 KRB5_KEYUSAGE_FAST_REQ_CHKSUM, to_be_checksummed,
244 &armored_req->req_checksum);
246 retval = krb5_encrypt_helper(context, state->armor_key,
247 KRB5_KEYUSAGE_FAST_ENC, encoded_fast_req,
248 &armored_req->enc_part);
250 retval = encode_krb5_pa_fx_fast_request(armored_req, &encoded_armored_req);
252 pa[0].pa_type = KRB5_PADATA_FX_FAST;
253 pa[0].contents = (unsigned char *) encoded_armored_req->data;
254 pa[0].length = encoded_armored_req->length;
255 pa_array[0] = &pa[0];
257 state->fast_outer_request.padata = pa_array;
259 retval = encoder(&state->fast_outer_request, &local_encoded_result);
261 *encoded_request = local_encoded_result;
262 local_encoded_result = NULL;
264 if (encoded_armored_req)
265 krb5_free_data(context, encoded_armored_req);
267 armored_req->armor = NULL; /*owned by state*/
268 krb5_free_fast_armored_req(context, armored_req);
270 if (encoded_fast_req)
271 krb5_free_data(context, encoded_fast_req);
272 if (local_encoded_result)
273 krb5_free_data(context, local_encoded_result);
274 state->fast_outer_request.padata = NULL;
278 static krb5_error_code
279 decrypt_fast_reply(krb5_context context,
280 struct krb5int_fast_request_state *state,
281 krb5_pa_data **in_padata,
282 krb5_fast_response **response)
284 krb5_error_code retval = 0;
286 krb5_enc_data *encrypted_response = NULL;
287 krb5_pa_data *fx_reply = NULL;
288 krb5_fast_response *local_resp = NULL;
289 assert(state != NULL);
290 assert(state->armor_key);
291 fx_reply = krb5int_find_pa_data(context, in_padata, KRB5_PADATA_FX_FAST);
292 if (fx_reply == NULL)
293 retval = KRB5_ERR_FAST_REQUIRED;
295 scratch.data = (char *) fx_reply->contents;
296 scratch.length = fx_reply->length;
297 retval = decode_krb5_pa_fx_fast_reply(&scratch, &encrypted_response);
301 scratch.data = malloc(encrypted_response->ciphertext.length);
302 if (scratch.data == NULL)
304 scratch.length = encrypted_response->ciphertext.length;
307 retval = krb5_c_decrypt(context, state->armor_key,
308 KRB5_KEYUSAGE_FAST_REP, NULL,
309 encrypted_response, &scratch);
312 errmsg = krb5_get_error_message(context, retval);
313 krb5_set_error_message(context, retval, "%s while decrypting FAST reply", errmsg);
314 krb5_free_error_message(context, errmsg);
317 retval = decode_krb5_fast_response(&scratch, &local_resp);
319 if (local_resp->nonce != state->nonce) {
320 retval = KRB5_KDCREP_MODIFIED;
321 krb5_set_error_message(context, retval, "nonce modified in FAST response: KDC response modified");
325 *response = local_resp;
330 if (encrypted_response)
331 krb5_free_enc_data(context, encrypted_response);
333 krb5_free_fast_response(context, local_resp);
338 * FAST separates two concepts: the set of padata we're using to
339 * decide what pre-auth mechanisms to use and the set of padata we're
340 * making available to mechanisms in order for them to respond to an
341 * error. The plugin interface in March 2009 does not permit
342 * separating these concepts for the plugins. This function makes
343 * both available for future revisions to the plugin interface. It
344 * also re-encodes the padata from the current error as a encoded
345 * typed-data and puts that in the e_data field. That will allow
346 * existing plugins with the old interface to find the error data.
347 * The output parameter out_padata contains the padata from the error
348 * whenever padata is available (all the time with fast).
351 krb5int_fast_process_error(krb5_context context,
352 struct krb5int_fast_request_state *state,
353 krb5_error **err_replyptr,
354 krb5_pa_data ***out_padata,
357 krb5_error_code retval = 0;
358 krb5_error *err_reply = *err_replyptr;
361 if (state->armor_key) {
362 krb5_pa_data *fx_error_pa;
363 krb5_pa_data **result = NULL;
364 krb5_data scratch, *encoded_td = NULL;
365 krb5_error *fx_error = NULL;
366 krb5_fast_response *fast_response = NULL;
367 retval = decode_krb5_padata_sequence(&err_reply->e_data, &result);
369 retval = decrypt_fast_reply(context, state, result, &fast_response);
371 /*This can happen if the KDC does not understand FAST. We
372 * don't expect that, but treating it as the fatal error
373 * indicated by the KDC seems reasonable.
376 krb5_free_pa_data(context, result);
379 krb5_free_pa_data(context, result);
382 fx_error_pa = krb5int_find_pa_data(context, fast_response->padata, KRB5_PADATA_FX_ERROR);
383 if (fx_error_pa == NULL) {
384 krb5_set_error_message(context, KRB5KDC_ERR_PREAUTH_FAILED, "Expecting FX_ERROR pa-data inside FAST container");
385 retval = KRB5KDC_ERR_PREAUTH_FAILED;
389 scratch.data = (char *) fx_error_pa->contents;
390 scratch.length = fx_error_pa->length;
391 retval = decode_krb5_error(&scratch, &fx_error);
394 * krb5_pa_data and krb5_typed_data are safe to cast between:
395 * they have the same type fields in the same order.
396 * (krb5_preauthtype is a krb5_int32). If krb5_typed_data is
397 * ever changed then this will need to be a copy not a cast.
400 retval = encode_krb5_typed_data( (const krb5_typed_data **)fast_response->padata,
403 fx_error->e_data = *encoded_td;
404 free(encoded_td); /*contents owned by fx_error*/
406 krb5_free_error(context, err_reply);
407 *err_replyptr = fx_error;
409 *out_padata = fast_response->padata;
410 fast_response->padata = NULL;
412 * If there is more than the fx_error padata, then we want
413 * to retry the error if a cookie is present
415 *retry = (*out_padata)[1] != NULL;
416 if (krb5int_find_pa_data(context, *out_padata, KRB5_PADATA_FX_COOKIE) == NULL)
420 krb5_free_error(context, fx_error);
421 krb5_free_fast_response(context, fast_response);
422 } else { /*not FAST*/
423 *retry = (err_reply->e_data.length > 0);
424 if ((err_reply->error == KDC_ERR_PREAUTH_REQUIRED
425 ||err_reply->error == KDC_ERR_PREAUTH_FAILED) && err_reply->e_data.length) {
426 krb5_pa_data **result = NULL;
427 retval = decode_krb5_padata_sequence(&err_reply->e_data, &result);
430 *out_padata = result;
434 krb5_free_pa_data(context, result);
435 krb5_set_error_message(context, retval,
436 "Error decoding padata in error reply");
445 krb5int_fast_process_response(krb5_context context,
446 struct krb5int_fast_request_state *state,
448 krb5_keyblock **strengthen_key)
450 krb5_error_code retval = 0;
451 krb5_fast_response *fast_response = NULL;
452 krb5_data *encoded_ticket = NULL;
453 krb5_boolean cksum_valid;
454 krb5_clear_error_message(context);
455 *strengthen_key = NULL;
456 if (state->armor_key == 0)
458 retval = decrypt_fast_reply(context, state, resp->padata,
461 if (fast_response->finished == 0) {
462 retval = KRB5_KDCREP_MODIFIED;
463 krb5_set_error_message(context, retval, "FAST response missing finish message in KDC reply");
467 retval = encode_krb5_ticket(resp->ticket, &encoded_ticket);
469 retval = krb5_c_verify_checksum(context, state->armor_key,
470 KRB5_KEYUSAGE_FAST_FINISHED,
472 &fast_response->finished->ticket_checksum,
474 if (retval == 0 && cksum_valid == 0) {
475 retval = KRB5_KDCREP_MODIFIED;
476 krb5_set_error_message(context, retval, "ticket modified in KDC reply");
479 krb5_free_principal(context, resp->client);
480 resp->client = fast_response->finished->client;
481 fast_response->finished->client = NULL;
482 *strengthen_key = fast_response->strengthen_key;
483 fast_response->strengthen_key = NULL;
484 krb5_free_pa_data(context, resp->padata);
485 resp->padata = fast_response->padata;
486 fast_response->padata = NULL;
489 krb5_free_fast_response(context, fast_response);
491 krb5_free_data(context, encoded_ticket);
496 krb5int_fast_reply_key(krb5_context context,
497 krb5_keyblock *strengthen_key,
498 krb5_keyblock *existing_key,
499 krb5_keyblock *out_key)
501 krb5_keyblock *key = NULL;
502 krb5_error_code retval = 0;
503 krb5_free_keyblock_contents(context, out_key);
504 if (strengthen_key) {
505 retval = krb5_c_fx_cf2_simple(context, strengthen_key,
506 "strengthenkey", existing_key, "replykey", &key);
512 retval = krb5_copy_keyblock_contents(context, existing_key, out_key);
519 krb5int_fast_make_state( krb5_context context, struct krb5int_fast_request_state **state)
521 struct krb5int_fast_request_state *local_state ;
522 local_state = malloc(sizeof *local_state);
523 if (local_state == NULL)
525 memset(local_state, 0, sizeof(*local_state));
526 *state = local_state;
531 krb5int_fast_free_state( krb5_context context, struct krb5int_fast_request_state *state)
533 /*We are responsible for none of the store in the fast_outer_req*/
534 krb5_free_keyblock(context, state->armor_key);
535 krb5_free_fast_armor(context, state->armor);
540 krb5int_find_pa_data(krb5_context context, krb5_pa_data *const *padata,
541 krb5_preauthtype pa_type)
543 krb5_pa_data * const *tmppa;
548 for (tmppa = padata; *tmppa != NULL; tmppa++) {
549 if ((*tmppa)->pa_type == pa_type)
558 krb5int_fast_verify_nego(krb5_context context,
559 struct krb5int_fast_request_state *state,
560 krb5_kdc_rep *rep, krb5_data *request,
561 krb5_keyblock *decrypting_key,
562 krb5_boolean *fast_avail)
564 krb5_error_code retval = 0;
565 krb5_checksum *checksum = NULL;
570 if (rep->enc_part2->flags& TKT_FLG_ENC_PA_REP) {
571 pa = krb5int_find_pa_data(context, rep->enc_part2->enc_padata,
572 KRB5_ENCPADATA_REQ_ENC_PA_REP);
574 retval = KRB5_KDCREP_MODIFIED;
576 scratch.data = (char *) pa->contents;
577 scratch.length = pa->length;
580 retval = decode_krb5_checksum(&scratch, &checksum);
582 retval = krb5_c_verify_checksum(context, decrypting_key,
583 KRB5_KEYUSAGE_AS_REQ,
584 request, checksum, &valid);
585 if (retval == 0 &&valid == 0)
586 retval = KRB5_KDCREP_MODIFIED;
588 pa = krb5int_find_pa_data(context, rep->enc_part2->enc_padata,
589 KRB5_PADATA_FX_FAST);
590 *fast_avail = (pa != NULL);
594 krb5_free_checksum(context, checksum);
599 krb5int_upgrade_to_fast_p(krb5_context context,
600 struct krb5int_fast_request_state *state,
601 krb5_pa_data **padata)
603 if (state->armor_key != NULL)
604 return 0; /*already using FAST*/
605 if (!(state->fast_state_flags & KRB5INT_FAST_ARMOR_AVAIL))
607 if (krb5int_find_pa_data(context, padata, KRB5_PADATA_FX_FAST) != NULL) {
608 state->fast_state_flags |= KRB5INT_FAST_DO_FAST;