1 /*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <keymaster/keymaster_enforcement.h>
18
19 #include <assert.h>
20 #include <limits.h>
21 #include <string.h>
22
23 #include <openssl/evp.h>
24
25 #include <hardware/hw_auth_token.h>
26 #include <keymaster/android_keymaster_utils.h>
27 #include <keymaster/logger.h>
28 #include <keymaster/List.h>
29
30 namespace keymaster {
31
32 class AccessTimeMap {
33 public:
AccessTimeMap(uint32_t max_size)34 explicit AccessTimeMap(uint32_t max_size) : max_size_(max_size) {}
35
36 /* If the key is found, returns true and fills \p last_access_time. If not found returns
37 * false. */
38 bool LastKeyAccessTime(km_id_t keyid, uint32_t* last_access_time) const;
39
40 /* Updates the last key access time with the currentTime parameter. Adds the key if
41 * needed, returning false if key cannot be added because list is full. */
42 bool UpdateKeyAccessTime(km_id_t keyid, uint32_t current_time, uint32_t timeout);
43
44 private:
45 struct AccessTime {
46 km_id_t keyid;
47 uint32_t access_time;
48 uint32_t timeout;
49 };
50 List<AccessTime> last_access_list_;
51 const uint32_t max_size_;
52 };
53
54 class AccessCountMap {
55 public:
AccessCountMap(uint32_t max_size)56 explicit AccessCountMap(uint32_t max_size) : max_size_(max_size) {}
57
58 /* If the key is found, returns true and fills \p count. If not found returns
59 * false. */
60 bool KeyAccessCount(km_id_t keyid, uint32_t* count) const;
61
62 /* Increments key access count, adding an entry if the key has never been used. Returns
63 * false if the list has reached maximum size. */
64 bool IncrementKeyAccessCount(km_id_t keyid);
65
66 private:
67 struct AccessCount {
68 km_id_t keyid;
69 uint64_t access_count;
70 };
71 List<AccessCount> access_count_list_;
72 const uint32_t max_size_;
73 };
74
is_public_key_algorithm(const AuthProxy & auth_set)75 bool is_public_key_algorithm(const AuthProxy& auth_set) {
76 keymaster_algorithm_t algorithm;
77 return auth_set.GetTagValue(TAG_ALGORITHM, &algorithm) &&
78 (algorithm == KM_ALGORITHM_RSA || algorithm == KM_ALGORITHM_EC);
79 }
80
authorized_purpose(const keymaster_purpose_t purpose,const AuthProxy & auth_set)81 static keymaster_error_t authorized_purpose(const keymaster_purpose_t purpose,
82 const AuthProxy& auth_set) {
83 switch (purpose) {
84 case KM_PURPOSE_VERIFY:
85 case KM_PURPOSE_ENCRYPT:
86 case KM_PURPOSE_SIGN:
87 case KM_PURPOSE_DECRYPT:
88 case KM_PURPOSE_WRAP:
89 if (auth_set.Contains(TAG_PURPOSE, purpose))
90 return KM_ERROR_OK;
91 return KM_ERROR_INCOMPATIBLE_PURPOSE;
92
93 default:
94 return KM_ERROR_UNSUPPORTED_PURPOSE;
95 }
96 }
97
is_origination_purpose(keymaster_purpose_t purpose)98 inline bool is_origination_purpose(keymaster_purpose_t purpose) {
99 return purpose == KM_PURPOSE_ENCRYPT || purpose == KM_PURPOSE_SIGN;
100 }
101
is_usage_purpose(keymaster_purpose_t purpose)102 inline bool is_usage_purpose(keymaster_purpose_t purpose) {
103 return purpose == KM_PURPOSE_DECRYPT || purpose == KM_PURPOSE_VERIFY;
104 }
105
KeymasterEnforcement(uint32_t max_access_time_map_size,uint32_t max_access_count_map_size)106 KeymasterEnforcement::KeymasterEnforcement(uint32_t max_access_time_map_size,
107 uint32_t max_access_count_map_size)
108 : access_time_map_(new (std::nothrow) AccessTimeMap(max_access_time_map_size)),
109 access_count_map_(new (std::nothrow) AccessCountMap(max_access_count_map_size)) {}
110
~KeymasterEnforcement()111 KeymasterEnforcement::~KeymasterEnforcement() {
112 delete access_time_map_;
113 delete access_count_map_;
114 }
115
AuthorizeOperation(const keymaster_purpose_t purpose,const km_id_t keyid,const AuthProxy & auth_set,const AuthorizationSet & operation_params,keymaster_operation_handle_t op_handle,bool is_begin_operation)116 keymaster_error_t KeymasterEnforcement::AuthorizeOperation(const keymaster_purpose_t purpose,
117 const km_id_t keyid,
118 const AuthProxy& auth_set,
119 const AuthorizationSet& operation_params,
120 keymaster_operation_handle_t op_handle,
121 bool is_begin_operation) {
122 if (is_public_key_algorithm(auth_set)) {
123 switch (purpose) {
124 case KM_PURPOSE_ENCRYPT:
125 case KM_PURPOSE_VERIFY:
126 /* Public key operations are always authorized. */
127 return KM_ERROR_OK;
128
129 case KM_PURPOSE_DECRYPT:
130 case KM_PURPOSE_SIGN:
131 case KM_PURPOSE_DERIVE_KEY:
132 case KM_PURPOSE_WRAP:
133 break;
134 };
135 };
136
137 if (is_begin_operation)
138 return AuthorizeBegin(purpose, keyid, auth_set, operation_params);
139 else
140 return AuthorizeUpdateOrFinish(auth_set, operation_params, op_handle);
141 }
142
143 // For update and finish the only thing to check is user authentication, and then only if it's not
144 // timeout-based.
145 keymaster_error_t
AuthorizeUpdateOrFinish(const AuthProxy & auth_set,const AuthorizationSet & operation_params,keymaster_operation_handle_t op_handle)146 KeymasterEnforcement::AuthorizeUpdateOrFinish(const AuthProxy& auth_set,
147 const AuthorizationSet& operation_params,
148 keymaster_operation_handle_t op_handle) {
149 int auth_type_index = -1;
150 int trusted_confirmation_index = -1;
151 bool no_auth_required = false;
152 for (size_t pos = 0; pos < auth_set.size(); ++pos) {
153 switch (auth_set[pos].tag) {
154 case KM_TAG_USER_AUTH_TYPE:
155 auth_type_index = pos;
156 break;
157
158 case KM_TAG_TRUSTED_CONFIRMATION_REQUIRED:
159 trusted_confirmation_index = pos;
160 break;
161 case KM_TAG_NO_AUTH_REQUIRED:
162 case KM_TAG_AUTH_TIMEOUT:
163 // If no auth is required or if auth is timeout-based, we have nothing to check.
164 no_auth_required = true;
165 break;
166 default:
167 break;
168 }
169 }
170
171 // TODO verify trusted confirmation mac once we have a shared secret established
172 // For now, since we do not have such a service, any token offered here must be invalid.
173 if (trusted_confirmation_index != -1) {
174 return KM_ERROR_NO_USER_CONFIRMATION;
175 }
176
177 // If NO_AUTH_REQUIRED or AUTH_TIMEOUT was set, we need not check an auth token.
178 if (no_auth_required) {
179 return KM_ERROR_OK;
180 }
181
182 // Note that at this point we should be able to assume that authentication is required, because
183 // authentication is required if KM_TAG_NO_AUTH_REQUIRED is absent. However, there are legacy
184 // keys which have no authentication-related tags, so we assume that absence is equivalent to
185 // presence of KM_TAG_NO_AUTH_REQUIRED.
186 //
187 // So, if we found KM_TAG_USER_AUTH_TYPE or if we find KM_TAG_USER_SECURE_ID then authentication
188 // is required. If we find neither, then we assume authentication is not required and return
189 // success.
190 bool authentication_required = (auth_type_index != -1);
191 for (auto& param : auth_set) {
192 if (param.tag == KM_TAG_USER_SECURE_ID) {
193 authentication_required = true;
194 int auth_timeout_index = -1;
195 if (AuthTokenMatches(auth_set, operation_params, param.long_integer, auth_type_index,
196 auth_timeout_index, op_handle, false /* is_begin_operation */))
197 return KM_ERROR_OK;
198 }
199 }
200
201 if (authentication_required) {
202 return KM_ERROR_KEY_USER_NOT_AUTHENTICATED;
203 }
204
205 return KM_ERROR_OK;
206 }
207
AuthorizeBegin(const keymaster_purpose_t purpose,const km_id_t keyid,const AuthProxy & auth_set,const AuthorizationSet & operation_params)208 keymaster_error_t KeymasterEnforcement::AuthorizeBegin(const keymaster_purpose_t purpose,
209 const km_id_t keyid,
210 const AuthProxy& auth_set,
211 const AuthorizationSet& operation_params) {
212 // Find some entries that may be needed to handle KM_TAG_USER_SECURE_ID
213 int auth_timeout_index = -1;
214 int auth_type_index = -1;
215 int no_auth_required_index = -1;
216 for (size_t pos = 0; pos < auth_set.size(); ++pos) {
217 switch (auth_set[pos].tag) {
218 case KM_TAG_AUTH_TIMEOUT:
219 auth_timeout_index = pos;
220 break;
221 case KM_TAG_USER_AUTH_TYPE:
222 auth_type_index = pos;
223 break;
224 case KM_TAG_NO_AUTH_REQUIRED:
225 no_auth_required_index = pos;
226 break;
227 default:
228 break;
229 }
230 }
231
232 keymaster_error_t error = authorized_purpose(purpose, auth_set);
233 if (error != KM_ERROR_OK)
234 return error;
235
236 // If successful, and if key has a min time between ops, this will be set to the time limit
237 uint32_t min_ops_timeout = UINT32_MAX;
238
239 bool update_access_count = false;
240 bool caller_nonce_authorized_by_key = false;
241 bool authentication_required = false;
242 bool auth_token_matched = false;
243
244 for (auto& param : auth_set) {
245
246 // KM_TAG_PADDING_OLD and KM_TAG_DIGEST_OLD aren't actually members of the enum, so we can't
247 // switch on them. There's nothing to validate for them, though, so just ignore them.
248 if (param.tag == KM_TAG_PADDING_OLD || param.tag == KM_TAG_DIGEST_OLD)
249 continue;
250
251 switch (param.tag) {
252
253 case KM_TAG_ACTIVE_DATETIME:
254 if (!activation_date_valid(param.date_time))
255 return KM_ERROR_KEY_NOT_YET_VALID;
256 break;
257
258 case KM_TAG_ORIGINATION_EXPIRE_DATETIME:
259 if (is_origination_purpose(purpose) && expiration_date_passed(param.date_time))
260 return KM_ERROR_KEY_EXPIRED;
261 break;
262
263 case KM_TAG_USAGE_EXPIRE_DATETIME:
264 if (is_usage_purpose(purpose) && expiration_date_passed(param.date_time))
265 return KM_ERROR_KEY_EXPIRED;
266 break;
267
268 case KM_TAG_MIN_SECONDS_BETWEEN_OPS:
269 min_ops_timeout = param.integer;
270 if (!MinTimeBetweenOpsPassed(min_ops_timeout, keyid))
271 return KM_ERROR_KEY_RATE_LIMIT_EXCEEDED;
272 break;
273
274 case KM_TAG_MAX_USES_PER_BOOT:
275 update_access_count = true;
276 if (!MaxUsesPerBootNotExceeded(keyid, param.integer))
277 return KM_ERROR_KEY_MAX_OPS_EXCEEDED;
278 break;
279
280 case KM_TAG_USER_SECURE_ID:
281 if (no_auth_required_index != -1) {
282 // Key has both KM_TAG_USER_SECURE_ID and KM_TAG_NO_AUTH_REQUIRED
283 return KM_ERROR_INVALID_KEY_BLOB;
284 }
285
286 if (auth_timeout_index != -1) {
287 authentication_required = true;
288 if (AuthTokenMatches(auth_set, operation_params, param.long_integer,
289 auth_type_index, auth_timeout_index, 0 /* op_handle */,
290 true /* is_begin_operation */))
291 auth_token_matched = true;
292 }
293 break;
294
295 case KM_TAG_UNLOCKED_DEVICE_REQUIRED:
296 if (device_locked_at_ > 0) {
297 const hw_auth_token_t* auth_token;
298 uint32_t token_auth_type;
299 if (!GetAndValidateAuthToken(operation_params, &auth_token, &token_auth_type)) {
300 return KM_ERROR_DEVICE_LOCKED;
301 }
302
303 uint64_t token_timestamp_millis = ntoh(auth_token->timestamp);
304 if (token_timestamp_millis <= device_locked_at_ ||
305 (password_unlock_only_ && !(token_auth_type & HW_AUTH_PASSWORD))) {
306 return KM_ERROR_DEVICE_LOCKED;
307 }
308 }
309 break;
310
311 case KM_TAG_CALLER_NONCE:
312 caller_nonce_authorized_by_key = true;
313 break;
314
315 /* Tags should never be in key auths. */
316 case KM_TAG_INVALID:
317 case KM_TAG_AUTH_TOKEN:
318 case KM_TAG_ROOT_OF_TRUST:
319 case KM_TAG_APPLICATION_DATA:
320 case KM_TAG_ATTESTATION_CHALLENGE:
321 case KM_TAG_ATTESTATION_APPLICATION_ID:
322 case KM_TAG_ATTESTATION_ID_BRAND:
323 case KM_TAG_ATTESTATION_ID_DEVICE:
324 case KM_TAG_ATTESTATION_ID_PRODUCT:
325 case KM_TAG_ATTESTATION_ID_SERIAL:
326 case KM_TAG_ATTESTATION_ID_IMEI:
327 case KM_TAG_ATTESTATION_ID_MEID:
328 case KM_TAG_ATTESTATION_ID_MANUFACTURER:
329 case KM_TAG_ATTESTATION_ID_MODEL:
330 case KM_TAG_DEVICE_UNIQUE_ATTESTATION:
331 return KM_ERROR_INVALID_KEY_BLOB;
332
333 /* Tags used for cryptographic parameters in keygen. Nothing to enforce. */
334 case KM_TAG_PURPOSE:
335 case KM_TAG_ALGORITHM:
336 case KM_TAG_KEY_SIZE:
337 case KM_TAG_BLOCK_MODE:
338 case KM_TAG_DIGEST:
339 case KM_TAG_MAC_LENGTH:
340 case KM_TAG_PADDING:
341 case KM_TAG_NONCE:
342 case KM_TAG_MIN_MAC_LENGTH:
343 case KM_TAG_KDF:
344 case KM_TAG_EC_CURVE:
345
346 /* Tags not used for operations. */
347 case KM_TAG_BLOB_USAGE_REQUIREMENTS:
348 case KM_TAG_EXPORTABLE:
349
350 /* Algorithm specific parameters not used for access control. */
351 case KM_TAG_RSA_PUBLIC_EXPONENT:
352 case KM_TAG_ECIES_SINGLE_HASH_MODE:
353
354 /* Informational tags. */
355 case KM_TAG_CREATION_DATETIME:
356 case KM_TAG_ORIGIN:
357 case KM_TAG_ROLLBACK_RESISTANCE:
358 case KM_TAG_ROLLBACK_RESISTANT:
359 case KM_TAG_USER_ID:
360
361 /* Tags handled when KM_TAG_USER_SECURE_ID is handled */
362 case KM_TAG_NO_AUTH_REQUIRED:
363 case KM_TAG_USER_AUTH_TYPE:
364 case KM_TAG_AUTH_TIMEOUT:
365
366 /* Tag to provide data to operations. */
367 case KM_TAG_ASSOCIATED_DATA:
368
369 /* Tags that are implicitly verified by secure side */
370 case KM_TAG_ALL_APPLICATIONS:
371 case KM_TAG_APPLICATION_ID:
372 case KM_TAG_OS_VERSION:
373 case KM_TAG_OS_PATCHLEVEL:
374
375 /* Ignored pending removal */
376 case KM_TAG_ALL_USERS:
377
378 /* TODO(swillden): Handle these */
379 case KM_TAG_INCLUDE_UNIQUE_ID:
380 case KM_TAG_UNIQUE_ID:
381 case KM_TAG_RESET_SINCE_ID_ROTATION:
382 case KM_TAG_ALLOW_WHILE_ON_BODY:
383 case KM_TAG_TRUSTED_CONFIRMATION_REQUIRED:
384 break;
385
386 case KM_TAG_IDENTITY_CREDENTIAL_KEY:
387 case KM_TAG_BOOTLOADER_ONLY:
388 return KM_ERROR_INVALID_KEY_BLOB;
389
390 case KM_TAG_EARLY_BOOT_ONLY:
391 if (!in_early_boot()) return KM_ERROR_EARLY_BOOT_ENDED;
392 break;
393 }
394 }
395
396 if (authentication_required && !auth_token_matched) {
397 LOG_E("Auth required but no matching auth token found", 0);
398 return KM_ERROR_KEY_USER_NOT_AUTHENTICATED;
399 }
400
401 if (!caller_nonce_authorized_by_key && is_origination_purpose(purpose) &&
402 operation_params.find(KM_TAG_NONCE) != -1)
403 return KM_ERROR_CALLER_NONCE_PROHIBITED;
404
405 if (min_ops_timeout != UINT32_MAX) {
406 if (!access_time_map_) {
407 LOG_S("Rate-limited keys table not allocated. Rate-limited keys disabled", 0);
408 return KM_ERROR_MEMORY_ALLOCATION_FAILED;
409 }
410
411 if (!access_time_map_->UpdateKeyAccessTime(keyid, get_current_time(), min_ops_timeout)) {
412 LOG_E("Rate-limited keys table full. Entries will time out.", 0);
413 return KM_ERROR_TOO_MANY_OPERATIONS;
414 }
415 }
416
417 if (update_access_count) {
418 if (!access_count_map_) {
419 LOG_S("Usage-count limited keys table not allocated. Count-limited keys disabled", 0);
420 return KM_ERROR_MEMORY_ALLOCATION_FAILED;
421 }
422
423 if (!access_count_map_->IncrementKeyAccessCount(keyid)) {
424 LOG_E("Usage count-limited keys table full, until reboot.", 0);
425 return KM_ERROR_TOO_MANY_OPERATIONS;
426 }
427 }
428
429 return KM_ERROR_OK;
430 }
431
MinTimeBetweenOpsPassed(uint32_t min_time_between,const km_id_t keyid)432 bool KeymasterEnforcement::MinTimeBetweenOpsPassed(uint32_t min_time_between, const km_id_t keyid) {
433 if (!access_time_map_)
434 return false;
435
436 uint32_t last_access_time;
437 if (!access_time_map_->LastKeyAccessTime(keyid, &last_access_time))
438 return true;
439 return min_time_between <= static_cast<int64_t>(get_current_time()) - last_access_time;
440 }
441
MaxUsesPerBootNotExceeded(const km_id_t keyid,uint32_t max_uses)442 bool KeymasterEnforcement::MaxUsesPerBootNotExceeded(const km_id_t keyid, uint32_t max_uses) {
443 if (!access_count_map_)
444 return false;
445
446 uint32_t key_access_count;
447 if (!access_count_map_->KeyAccessCount(keyid, &key_access_count))
448 return true;
449 return key_access_count < max_uses;
450 }
451
GetAndValidateAuthToken(const AuthorizationSet & operation_params,const hw_auth_token_t ** auth_token,uint32_t * token_auth_type) const452 bool KeymasterEnforcement::GetAndValidateAuthToken(const AuthorizationSet& operation_params,
453 const hw_auth_token_t** auth_token,
454 uint32_t* token_auth_type) const {
455 keymaster_blob_t auth_token_blob;
456 if (!operation_params.GetTagValue(TAG_AUTH_TOKEN, &auth_token_blob)) {
457 LOG_E("Authentication required, but auth token not provided", 0);
458 return false;
459 }
460
461 if (auth_token_blob.data_length != sizeof(**auth_token)) {
462 LOG_E("Bug: Auth token is the wrong size (%d expected, %d found)", sizeof(hw_auth_token_t),
463 auth_token_blob.data_length);
464 return false;
465 }
466
467 *auth_token = reinterpret_cast<const hw_auth_token_t*>(auth_token_blob.data);
468 if ((*auth_token)->version != HW_AUTH_TOKEN_VERSION) {
469 LOG_E("Bug: Auth token is the version %d (or is not an auth token). Expected %d",
470 (*auth_token)->version, HW_AUTH_TOKEN_VERSION);
471 return false;
472 }
473
474 if (!ValidateTokenSignature(**auth_token)) {
475 LOG_E("Auth token signature invalid", 0);
476 return false;
477 }
478
479 *token_auth_type = ntoh((*auth_token)->authenticator_type);
480
481 return true;
482 }
483
AuthTokenMatches(const AuthProxy & auth_set,const AuthorizationSet & operation_params,const uint64_t user_secure_id,const int auth_type_index,const int auth_timeout_index,const keymaster_operation_handle_t op_handle,bool is_begin_operation) const484 bool KeymasterEnforcement::AuthTokenMatches(const AuthProxy& auth_set,
485 const AuthorizationSet& operation_params,
486 const uint64_t user_secure_id,
487 const int auth_type_index, const int auth_timeout_index,
488 const keymaster_operation_handle_t op_handle,
489 bool is_begin_operation) const {
490 assert(auth_type_index < static_cast<int>(auth_set.size()));
491 assert(auth_timeout_index < static_cast<int>(auth_set.size()));
492
493 const hw_auth_token_t* auth_token;
494 uint32_t token_auth_type;
495 if (!GetAndValidateAuthToken(operation_params, &auth_token, &token_auth_type)) return false;
496
497 if (auth_timeout_index == -1 && op_handle && op_handle != auth_token->challenge) {
498 LOG_E("Auth token has the challenge %llu, need %llu", auth_token->challenge, op_handle);
499 return false;
500 }
501
502 if (user_secure_id != auth_token->user_id && user_secure_id != auth_token->authenticator_id) {
503 LOG_I("Auth token SIDs %llu and %llu do not match key SID %llu", auth_token->user_id,
504 auth_token->authenticator_id, user_secure_id);
505 return false;
506 }
507
508 if (auth_type_index < 0 || auth_type_index > static_cast<int>(auth_set.size())) {
509 LOG_E("Auth required but no auth type found", 0);
510 return false;
511 }
512
513 assert(auth_set[auth_type_index].tag == KM_TAG_USER_AUTH_TYPE);
514 if (auth_set[auth_type_index].tag != KM_TAG_USER_AUTH_TYPE)
515 return false;
516
517 uint32_t key_auth_type_mask = auth_set[auth_type_index].integer;
518 if ((key_auth_type_mask & token_auth_type) == 0) {
519 LOG_E("Key requires match of auth type mask 0%uo, but token contained 0%uo",
520 key_auth_type_mask, token_auth_type);
521 return false;
522 }
523
524 if (auth_timeout_index != -1 && is_begin_operation) {
525 assert(auth_set[auth_timeout_index].tag == KM_TAG_AUTH_TIMEOUT);
526 if (auth_set[auth_timeout_index].tag != KM_TAG_AUTH_TIMEOUT)
527 return false;
528
529 if (auth_token_timed_out(*auth_token, auth_set[auth_timeout_index].integer)) {
530 LOG_E("Auth token has timed out", 0);
531 return false;
532 }
533 }
534
535 // Survived the whole gauntlet. We have authentage!
536 return true;
537 }
538
LastKeyAccessTime(km_id_t keyid,uint32_t * last_access_time) const539 bool AccessTimeMap::LastKeyAccessTime(km_id_t keyid, uint32_t* last_access_time) const {
540 for (auto& entry : last_access_list_)
541 if (entry.keyid == keyid) {
542 *last_access_time = entry.access_time;
543 return true;
544 }
545 return false;
546 }
547
UpdateKeyAccessTime(km_id_t keyid,uint32_t current_time,uint32_t timeout)548 bool AccessTimeMap::UpdateKeyAccessTime(km_id_t keyid, uint32_t current_time, uint32_t timeout) {
549 List<AccessTime>::iterator iter;
550 for (iter = last_access_list_.begin(); iter != last_access_list_.end();) {
551 if (iter->keyid == keyid) {
552 iter->access_time = current_time;
553 return true;
554 }
555
556 // Expire entry if possible.
557 assert(current_time >= iter->access_time);
558 if (current_time - iter->access_time >= iter->timeout)
559 iter = last_access_list_.erase(iter);
560 else
561 ++iter;
562 }
563
564 if (last_access_list_.size() >= max_size_)
565 return false;
566
567 AccessTime new_entry;
568 new_entry.keyid = keyid;
569 new_entry.access_time = current_time;
570 new_entry.timeout = timeout;
571 last_access_list_.push_front(new_entry);
572 return true;
573 }
574
KeyAccessCount(km_id_t keyid,uint32_t * count) const575 bool AccessCountMap::KeyAccessCount(km_id_t keyid, uint32_t* count) const {
576 for (auto& entry : access_count_list_)
577 if (entry.keyid == keyid) {
578 *count = entry.access_count;
579 return true;
580 }
581 return false;
582 }
583
IncrementKeyAccessCount(km_id_t keyid)584 bool AccessCountMap::IncrementKeyAccessCount(km_id_t keyid) {
585 for (auto& entry : access_count_list_)
586 if (entry.keyid == keyid) {
587 // Note that the 'if' below will always be true because KM_TAG_MAX_USES_PER_BOOT is a
588 // uint32_t, and as soon as entry.access_count reaches the specified maximum value
589 // operation requests will be rejected and access_count won't be incremented any more.
590 // And, besides, UINT64_MAX is huge. But we ensure that it doesn't wrap anyway, out of
591 // an abundance of caution.
592 if (entry.access_count < UINT64_MAX)
593 ++entry.access_count;
594 return true;
595 }
596
597 if (access_count_list_.size() >= max_size_)
598 return false;
599
600 AccessCount new_entry;
601 new_entry.keyid = keyid;
602 new_entry.access_count = 1;
603 access_count_list_.push_front(new_entry);
604 return true;
605 }
606 }; /* namespace keymaster */
607