1 /* 2 * Copyright (c) 2019-2020, Arm Limited. All rights reserved. 3 * 4 * SPDX-License-Identifier: Apache-2.0 5 */ 6 7 #ifndef __SECURITY_CNT_H__ 8 #define __SECURITY_CNT_H__ 9 10 /** 11 * @file security_cnt.h 12 * 13 * @note The interface must be implemented in a fail-safe way that is 14 * resistant to asynchronous power failures or it can use hardware 15 * counters that have this capability, if supported by the platform. 16 * When a counter incrementation was interrupted it must be able to 17 * continue the incrementation process or recover the previous consistent 18 * status of the counters. If the counters have reached a stable status 19 * (every counter incrementation operation has finished), from that point 20 * their value cannot decrease due to any kind of power failure. 21 * 22 * @note A security counter might be implemented using non-volatile OTP memory 23 * (i.e. fuses) in which case it is the responsibility of the platform 24 * code to map each possible security counter values onto the fuse bits 25 * as the direct usage of counter values can be costly / impractical. 26 */ 27 28 #include <stdint.h> 29 #include "bootutil/fault_injection_hardening.h" 30 31 #ifdef __cplusplus 32 extern "C" { 33 #endif 34 35 /** 36 * Initialises the security counters. 37 * 38 * @return FIH_SUCCESS on success 39 */ 40 fih_ret boot_nv_security_counter_init(void); 41 42 /** 43 * Reads the stored value of a given image's security counter. 44 * 45 * @param image_id Index of the image (from 0). 46 * @param security_cnt Pointer to store the security counter value. 47 * 48 * @return FIH_SUCCESS on success 49 */ 50 fih_ret boot_nv_security_counter_get(uint32_t image_id, fih_int *security_cnt); 51 52 /** 53 * Updates the stored value of a given image's security counter with a new 54 * security counter value if the new one is greater. 55 * 56 * @param image_id Index of the image (from 0). 57 * @param img_security_cnt New security counter value. The new value must be 58 * between 0 and UINT32_MAX and it must be greater than 59 * or equal to the current security counter value. 60 * 61 * @return 0 on success; nonzero on failure. 62 */ 63 int32_t boot_nv_security_counter_update(uint32_t image_id, 64 uint32_t img_security_cnt); 65 66 #ifdef __cplusplus 67 } 68 #endif 69 70 #endif /* __SECURITY_CNT_H__ */ 71
