1 /*
2 * PSA crypto layer on top of Mbed TLS crypto
3 */
4 /*
5 * Copyright The Mbed TLS Contributors
6 * SPDX-License-Identifier: Apache-2.0
7 *
8 * Licensed under the Apache License, Version 2.0 (the "License"); you may
9 * not use this file except in compliance with the License.
10 * You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing, software
15 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
16 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17 * See the License for the specific language governing permissions and
18 * limitations under the License.
19 */
20
21 #ifndef PSA_CRYPTO_SLOT_MANAGEMENT_H
22 #define PSA_CRYPTO_SLOT_MANAGEMENT_H
23
24 #include "psa/crypto.h"
25 #include "psa_crypto_core.h"
26 #include "psa_crypto_se.h"
27
28 /** Range of volatile key identifiers.
29 *
30 * The last #MBEDTLS_PSA_KEY_SLOT_COUNT identifiers of the implementation
31 * range of key identifiers are reserved for volatile key identifiers.
32 * A volatile key identifier is equal to #PSA_KEY_ID_VOLATILE_MIN plus the
33 * index of the key slot containing the volatile key definition.
34 */
35
36 /** The minimum value for a volatile key identifier.
37 */
38 #define PSA_KEY_ID_VOLATILE_MIN ( PSA_KEY_ID_VENDOR_MAX - \
39 MBEDTLS_PSA_KEY_SLOT_COUNT + 1 )
40
41 /** The maximum value for a volatile key identifier.
42 */
43 #define PSA_KEY_ID_VOLATILE_MAX PSA_KEY_ID_VENDOR_MAX
44
45 /** Test whether a key identifier is a volatile key identifier.
46 *
47 * \param key_id Key identifier to test.
48 *
49 * \retval 1
50 * The key identifier is a volatile key identifier.
51 * \retval 0
52 * The key identifier is not a volatile key identifier.
53 */
psa_key_id_is_volatile(psa_key_id_t key_id)54 static inline int psa_key_id_is_volatile( psa_key_id_t key_id )
55 {
56 return( ( key_id >= PSA_KEY_ID_VOLATILE_MIN ) &&
57 ( key_id <= PSA_KEY_ID_VOLATILE_MAX ) );
58 }
59
60 /** Get the description of a key given its identifier and lock it.
61 *
62 * The descriptions of volatile keys and loaded persistent keys are stored in
63 * key slots. This function returns a pointer to the key slot containing the
64 * description of a key given its identifier.
65 *
66 * In case of a persistent key, the function loads the description of the key
67 * into a key slot if not already done.
68 *
69 * On success, the returned key slot is locked. It is the responsibility of
70 * the caller to unlock the key slot when it does not access it anymore.
71 *
72 * \param key Key identifier to query.
73 * \param[out] p_slot On success, `*p_slot` contains a pointer to the
74 * key slot containing the description of the key
75 * identified by \p key.
76 *
77 * \retval #PSA_SUCCESS
78 * \p *p_slot contains a pointer to the key slot containing the
79 * description of the key identified by \p key.
80 * The key slot counter has been incremented.
81 * \retval #PSA_ERROR_BAD_STATE
82 * The library has not been initialized.
83 * \retval #PSA_ERROR_INVALID_HANDLE
84 * \p key is not a valid key identifier.
85 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
86 * \p key is a persistent key identifier. The implementation does not
87 * have sufficient resources to load the persistent key. This can be
88 * due to a lack of empty key slot, or available memory.
89 * \retval #PSA_ERROR_DOES_NOT_EXIST
90 * There is no key with key identifier \p key.
91 * \retval #PSA_ERROR_CORRUPTION_DETECTED
92 * \retval #PSA_ERROR_STORAGE_FAILURE
93 * \retval #PSA_ERROR_DATA_CORRUPT
94 */
95 psa_status_t psa_get_and_lock_key_slot( mbedtls_svc_key_id_t key,
96 psa_key_slot_t **p_slot );
97
98 /** Initialize the key slot structures.
99 *
100 * \retval #PSA_SUCCESS
101 * Currently this function always succeeds.
102 */
103 psa_status_t psa_initialize_key_slots( void );
104
105 /** Delete all data from key slots in memory.
106 *
107 * This does not affect persistent storage. */
108 void psa_wipe_all_key_slots( void );
109
110 /** Find a free key slot.
111 *
112 * This function returns a key slot that is available for use and is in its
113 * ground state (all-bits-zero). On success, the key slot is locked. It is
114 * the responsibility of the caller to unlock the key slot when it does not
115 * access it anymore.
116 *
117 * \param[out] volatile_key_id On success, volatile key identifier
118 * associated to the returned slot.
119 * \param[out] p_slot On success, a pointer to the slot.
120 *
121 * \retval #PSA_SUCCESS
122 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
123 * \retval #PSA_ERROR_BAD_STATE
124 */
125 psa_status_t psa_get_empty_key_slot( psa_key_id_t *volatile_key_id,
126 psa_key_slot_t **p_slot );
127
128 /** Lock a key slot.
129 *
130 * This function increments the key slot lock counter by one.
131 *
132 * \param[in] slot The key slot.
133 *
134 * \retval #PSA_SUCCESS
135 The key slot lock counter was incremented.
136 * \retval #PSA_ERROR_CORRUPTION_DETECTED
137 * The lock counter already reached its maximum value and was not
138 * increased.
139 */
psa_lock_key_slot(psa_key_slot_t * slot)140 static inline psa_status_t psa_lock_key_slot( psa_key_slot_t *slot )
141 {
142 if( slot->lock_count >= SIZE_MAX )
143 return( PSA_ERROR_CORRUPTION_DETECTED );
144
145 slot->lock_count++;
146
147 return( PSA_SUCCESS );
148 }
149
150 /** Unlock a key slot.
151 *
152 * This function decrements the key slot lock counter by one.
153 *
154 * \note To ease the handling of errors in retrieving a key slot
155 * a NULL input pointer is valid, and the function returns
156 * successfully without doing anything in that case.
157 *
158 * \param[in] slot The key slot.
159 * \retval #PSA_SUCCESS
160 * \p slot is NULL or the key slot lock counter has been
161 * decremented successfully.
162 * \retval #PSA_ERROR_CORRUPTION_DETECTED
163 * The lock counter was equal to 0.
164 *
165 */
166 psa_status_t psa_unlock_key_slot( psa_key_slot_t *slot );
167
168 /** Test whether a lifetime designates a key in an external cryptoprocessor.
169 *
170 * \param lifetime The lifetime to test.
171 *
172 * \retval 1
173 * The lifetime designates an external key. There should be a
174 * registered driver for this lifetime, otherwise the key cannot
175 * be created or manipulated.
176 * \retval 0
177 * The lifetime designates a key that is volatile or in internal
178 * storage.
179 */
psa_key_lifetime_is_external(psa_key_lifetime_t lifetime)180 static inline int psa_key_lifetime_is_external( psa_key_lifetime_t lifetime )
181 {
182 return( PSA_KEY_LIFETIME_GET_LOCATION( lifetime )
183 != PSA_KEY_LOCATION_LOCAL_STORAGE );
184 }
185
186 /** Validate a key's location.
187 *
188 * This function checks whether the key's attributes point to a location that
189 * is known to the PSA Core, and returns the driver function table if the key
190 * is to be found in an external location.
191 *
192 * \param[in] lifetime The key lifetime attribute.
193 * \param[out] p_drv On success, when a key is located in external
194 * storage, returns a pointer to the driver table
195 * associated with the key's storage location.
196 *
197 * \retval #PSA_SUCCESS
198 * \retval #PSA_ERROR_INVALID_ARGUMENT
199 */
200 psa_status_t psa_validate_key_location( psa_key_lifetime_t lifetime,
201 psa_se_drv_table_entry_t **p_drv );
202
203 /** Validate the persistence of a key.
204 *
205 * \param[in] lifetime The key lifetime attribute.
206 *
207 * \retval #PSA_SUCCESS
208 * \retval #PSA_ERROR_NOT_SUPPORTED The key is persistent but persistent keys
209 * are not supported.
210 */
211 psa_status_t psa_validate_key_persistence( psa_key_lifetime_t lifetime );
212
213 /** Validate a key identifier.
214 *
215 * \param[in] key The key identifier.
216 * \param[in] vendor_ok Non-zero to indicate that key identifiers in the
217 * vendor range are allowed, volatile key identifiers
218 * excepted \c 0 otherwise.
219 *
220 * \retval <> 0 if the key identifier is valid, 0 otherwise.
221 */
222 int psa_is_valid_key_id( mbedtls_svc_key_id_t key, int vendor_ok );
223
224 #endif /* PSA_CRYPTO_SLOT_MANAGEMENT_H */
225