1 /*
2 * ESP32 hardware accelerated SHA1/256/512 implementation
3 * based on mbedTLS FIPS-197 compliant version.
4 *
5 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
6 * Additions Copyright (C) 2016, Espressif Systems (Shanghai) PTE Ltd
7 * SPDX-License-Identifier: Apache-2.0
8 *
9 * Licensed under the Apache License, Version 2.0 (the "License"); you may
10 * not use this file except in compliance with the License.
11 * You may obtain a copy of the License at
12 *
13 * http://www.apache.org/licenses/LICENSE-2.0
14 *
15 * Unless required by applicable law or agreed to in writing, software
16 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
17 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
18 * See the License for the specific language governing permissions and
19 * limitations under the License.
20 *
21 */
22 /*
23 * The SHA-1 standard was published by NIST in 1993.
24 *
25 * http://www.itl.nist.gov/fipspubs/fip180-1.htm
26 */
27
28 #include <string.h>
29 #include <stdio.h>
30 #include <machine/endian.h>
31 #include <assert.h>
32
33 #include "freertos/FreeRTOS.h"
34 #include "freertos/semphr.h"
35 #include "esp_cpu.h"
36
37 #include "hal/sha_hal.h"
38 #include "hal/sha_types.h"
39 #include "sha/sha_parallel_engine.h"
40 #include "soc/hwcrypto_periph.h"
41 #include "esp_private/periph_ctrl.h"
42
43 /*
44 Single spinlock for SHA engine memory block
45 */
46 static portMUX_TYPE memory_block_lock = portMUX_INITIALIZER_UNLOCKED;
47
48
49 /* Binary semaphore managing the state of each concurrent SHA engine.
50
51 Available = noone is using this SHA engine
52 Taken = a SHA session is running on this SHA engine
53
54 Indexes:
55 0 = SHA1
56 1 = SHA2_256
57 2 = SHA2_384 or SHA2_512
58 */
59 static SemaphoreHandle_t engine_states[3];
60
61 static uint8_t engines_in_use;
62
63 /* Spinlock for engines_in_use counter
64 */
65 static portMUX_TYPE engines_in_use_lock = portMUX_INITIALIZER_UNLOCKED;
66
67 /* Return block size (in words) for a given SHA type */
block_length(esp_sha_type type)68 inline static size_t block_length(esp_sha_type type)
69 {
70 switch (type) {
71 case SHA1:
72 case SHA2_256:
73 return 64 / 4;
74 case SHA2_384:
75 case SHA2_512:
76 return 128 / 4;
77 default:
78 return 0;
79 }
80 }
81
82 /* Index into the engine_states array */
sha_engine_index(esp_sha_type type)83 inline static size_t sha_engine_index(esp_sha_type type)
84 {
85 switch (type) {
86 case SHA1:
87 return 0;
88 case SHA2_256:
89 return 1;
90 default:
91 return 2;
92 }
93 }
94
esp_sha_lock_memory_block(void)95 void esp_sha_lock_memory_block(void)
96 {
97 portENTER_CRITICAL(&memory_block_lock);
98 }
99
esp_sha_unlock_memory_block(void)100 void esp_sha_unlock_memory_block(void)
101 {
102 portEXIT_CRITICAL(&memory_block_lock);
103 }
104
sha_get_engine_state(esp_sha_type sha_type)105 static SemaphoreHandle_t sha_get_engine_state(esp_sha_type sha_type)
106 {
107 unsigned idx = sha_engine_index(sha_type);
108 volatile SemaphoreHandle_t *engine = &engine_states[idx];
109 SemaphoreHandle_t result = *engine;
110
111 if (result == NULL) {
112 // Create a new semaphore for 'in use' flag
113 SemaphoreHandle_t new_engine = xSemaphoreCreateBinary();
114 assert(new_engine != NULL);
115 xSemaphoreGive(new_engine); // start available
116
117 // try to atomically set the previously NULL *engine to new_engine
118 if (!esp_cpu_compare_and_set((volatile uint32_t *)engine, 0, (uint32_t)new_engine)) {
119 // we lost a race setting *engine
120 vSemaphoreDelete(new_engine);
121 }
122 result = *engine;
123 }
124 return result;
125 }
126
127 static bool esp_sha_lock_engine_common(esp_sha_type sha_type, TickType_t ticks_to_wait);
128
esp_sha_try_lock_engine(esp_sha_type sha_type)129 bool esp_sha_try_lock_engine(esp_sha_type sha_type)
130 {
131 return esp_sha_lock_engine_common(sha_type, 0);
132 }
133
esp_sha_lock_engine(esp_sha_type sha_type)134 void esp_sha_lock_engine(esp_sha_type sha_type)
135 {
136 esp_sha_lock_engine_common(sha_type, portMAX_DELAY);
137 }
138
esp_sha_lock_engine_common(esp_sha_type sha_type,TickType_t ticks_to_wait)139 static bool esp_sha_lock_engine_common(esp_sha_type sha_type, TickType_t ticks_to_wait)
140 {
141 SemaphoreHandle_t engine_state = sha_get_engine_state(sha_type);
142 BaseType_t result = xSemaphoreTake(engine_state, ticks_to_wait);
143
144 if (result == pdFALSE) {
145 // failed to take semaphore
146 return false;
147 }
148
149 portENTER_CRITICAL(&engines_in_use_lock);
150
151 if (engines_in_use == 0) {
152 /* Just locked first engine,
153 so enable SHA hardware */
154 periph_module_enable(PERIPH_SHA_MODULE);
155 }
156
157 engines_in_use++;
158 assert(engines_in_use <= 3);
159
160 portEXIT_CRITICAL(&engines_in_use_lock);
161
162 return true;
163 }
164
165
esp_sha_unlock_engine(esp_sha_type sha_type)166 void esp_sha_unlock_engine(esp_sha_type sha_type)
167 {
168 SemaphoreHandle_t engine_state = sha_get_engine_state(sha_type);
169
170 portENTER_CRITICAL(&engines_in_use_lock);
171
172 engines_in_use--;
173
174 if (engines_in_use == 0) {
175 /* About to release last engine, so
176 disable SHA hardware */
177 periph_module_disable(PERIPH_SHA_MODULE);
178 }
179
180 portEXIT_CRITICAL(&engines_in_use_lock);
181
182 xSemaphoreGive(engine_state);
183 }
184
esp_sha_read_digest_state(esp_sha_type sha_type,void * digest_state)185 void esp_sha_read_digest_state(esp_sha_type sha_type, void *digest_state)
186 {
187 #ifndef NDEBUG
188 {
189 SemaphoreHandle_t engine_state = sha_get_engine_state(sha_type);
190 assert(uxSemaphoreGetCount(engine_state) == 0 &&
191 "SHA engine should be locked" );
192 }
193 #endif
194
195 // preemptively do this before entering the critical section, then re-check once in it
196 sha_hal_wait_idle();
197
198 esp_sha_lock_memory_block();
199
200 sha_hal_read_digest(sha_type, digest_state);
201
202 esp_sha_unlock_memory_block();
203 }
204
esp_sha_block(esp_sha_type sha_type,const void * data_block,bool first_block)205 void esp_sha_block(esp_sha_type sha_type, const void *data_block, bool first_block)
206 {
207 #ifndef NDEBUG
208 {
209 SemaphoreHandle_t engine_state = sha_get_engine_state(sha_type);
210 assert(uxSemaphoreGetCount(engine_state) == 0 &&
211 "SHA engine should be locked" );
212 }
213 #endif
214
215 // preemptively do this before entering the critical section, then re-check once in it
216 sha_hal_wait_idle();
217 esp_sha_lock_memory_block();
218
219 sha_hal_hash_block(sha_type, data_block, block_length(sha_type), first_block);
220
221 esp_sha_unlock_memory_block();
222 }
223