1 // SPDX-License-Identifier: BSD-2-Clause 2 /* 3 * Copyright (c) 2022, Linaro Limited 4 * Copyright (c) 2022, Foundries.io Limited 5 */ 6 7 #include <assert.h> 8 #include <config.h> 9 #include <crypto/crypto.h> 10 #include <drivers/stm32_bsec.h> 11 #include <kernel/tee_common_otp.h> 12 #include <mempool.h> 13 #include <platform_config.h> 14 #include <stm32_util.h> 15 #include <string.h> 16 #include <string_ext.h> 17 18 static bool stm32mp15_huk_init; 19 20 static TEE_Result stm32mp15_read_uid(uint32_t *uid) 21 { 22 uint32_t *q = uid; 23 24 /* 25 * Shadow memory for UID words might not be locked: to guarante that 26 * the final values are read we must lock them. 27 */ 28 if (stm32_bsec_set_sw_lock(UID0_OTP) || 29 stm32_bsec_shadow_read_otp(q++, UID0_OTP)) 30 return TEE_ERROR_GENERIC; 31 32 if (stm32_bsec_set_sw_lock(UID1_OTP) || 33 stm32_bsec_shadow_read_otp(q++, UID1_OTP)) 34 return TEE_ERROR_GENERIC; 35 36 if (stm32_bsec_set_sw_lock(UID2_OTP) || 37 stm32_bsec_shadow_read_otp(q++, UID2_OTP)) 38 return TEE_ERROR_GENERIC; 39 40 return TEE_SUCCESS; 41 } 42 43 static TEE_Result stm32mp15_read_otp(uint32_t otp, uint32_t *key, bool *locked) 44 { 45 bool tmp = true; 46 uint32_t state = 0; 47 48 if (stm32_bsec_get_state(&state)) 49 panic(); 50 51 if (state != BSEC_STATE_SEC_CLOSED) { 52 /* 53 * When the device is not closed, the shadow memory for these 54 * words might not be locked: check and report them 55 */ 56 if (stm32_bsec_read_permanent_lock(otp, &tmp)) 57 return TEE_ERROR_GENERIC; 58 59 if (tmp && stm32_bsec_read_sw_lock(otp, &tmp)) 60 return TEE_ERROR_GENERIC; 61 } 62 63 if (stm32_bsec_shadow_read_otp(key, otp)) 64 return TEE_ERROR_GENERIC; 65 66 *locked = *locked && tmp; 67 68 return TEE_SUCCESS; 69 } 70 71 /* 72 * AES-GCM: nonce must be unique per message and key. 73 * 74 * This function always uses the same key - once its locked - with the same 75 * unique message hence the nonce can be any constant. 76 */ 77 static TEE_Result aes_gcm_encrypt_uid(uint8_t *key, size_t key_len, 78 uint8_t *out, size_t *out_len) 79 { 80 TEE_Result ret = TEE_ERROR_GENERIC; 81 const uint8_t nonce[12] = { 0x55 }; 82 uint32_t uid[4] = { 0 }; 83 uint8_t tag[16] = { 0 }; 84 size_t nonce_len = sizeof(nonce); 85 size_t tag_len = sizeof(tag); 86 size_t uid_len = sizeof(uid); 87 void *ctx = NULL; 88 89 ret = stm32mp15_read_uid(uid); 90 if (ret) 91 goto out; 92 93 ret = crypto_authenc_alloc_ctx(&ctx, TEE_ALG_AES_GCM); 94 if (ret) 95 goto out; 96 97 ret = crypto_authenc_init(ctx, TEE_MODE_ENCRYPT, key, key_len, nonce, 98 nonce_len, TEE_AES_BLOCK_SIZE, 0, uid_len); 99 if (ret) 100 goto out_free_ctx; 101 102 ret = crypto_authenc_enc_final(ctx, (uint8_t *)uid, sizeof(uid), 103 out, out_len, tag, &tag_len); 104 if (ret) 105 goto out_free_ctx; 106 107 crypto_authenc_final(ctx); 108 out_free_ctx: 109 crypto_authenc_free_ctx(ctx); 110 out: 111 if (ret) 112 memzero_explicit(out, *out_len); 113 114 return ret; 115 } 116 117 TEE_Result tee_otp_get_hw_unique_key(struct tee_hw_unique_key *hwkey) 118 { 119 uint32_t otp_key[4] = { 0 }; 120 size_t len = sizeof(otp_key); 121 TEE_Result ret = TEE_SUCCESS; 122 uint32_t *key = otp_key; 123 bool lock = true; 124 125 static_assert(CFG_STM32MP15_HUK_BSEC_KEY_0 < STM32MP1_OTP_MAX_ID); 126 static_assert(CFG_STM32MP15_HUK_BSEC_KEY_1 < STM32MP1_OTP_MAX_ID); 127 static_assert(CFG_STM32MP15_HUK_BSEC_KEY_2 < STM32MP1_OTP_MAX_ID); 128 static_assert(CFG_STM32MP15_HUK_BSEC_KEY_3 < STM32MP1_OTP_MAX_ID); 129 130 ret = stm32mp15_read_otp(CFG_STM32MP15_HUK_BSEC_KEY_0, key++, &lock); 131 if (ret) 132 goto out; 133 134 ret = stm32mp15_read_otp(CFG_STM32MP15_HUK_BSEC_KEY_1, key++, &lock); 135 if (ret) 136 goto out; 137 138 ret = stm32mp15_read_otp(CFG_STM32MP15_HUK_BSEC_KEY_2, key++, &lock); 139 if (ret) 140 goto out; 141 142 ret = stm32mp15_read_otp(CFG_STM32MP15_HUK_BSEC_KEY_3, key++, &lock); 143 if (ret) 144 goto out; 145 146 if (IS_ENABLED(CFG_STM32MP15_HUK_BSEC_KEY)) { 147 static_assert(sizeof(otp_key) == HW_UNIQUE_KEY_LENGTH); 148 memcpy(hwkey->data, otp_key, HW_UNIQUE_KEY_LENGTH); 149 ret = TEE_SUCCESS; 150 goto out; 151 } 152 153 if (IS_ENABLED(CFG_STM32MP15_HUK_BSEC_DERIVE_UID)) { 154 ret = aes_gcm_encrypt_uid((uint8_t *)otp_key, len, hwkey->data, 155 &len); 156 if (len != HW_UNIQUE_KEY_LENGTH) 157 ret = TEE_ERROR_GENERIC; 158 goto out; 159 } 160 161 panic(); 162 163 out: 164 memzero_explicit(otp_key, HW_UNIQUE_KEY_LENGTH); 165 166 if (!ret && !stm32mp15_huk_init) { 167 stm32mp15_huk_init = true; 168 IMSG("HUK %slocked", lock ? "" : "un"); 169 DHEXDUMP(hwkey->data, HW_UNIQUE_KEY_LENGTH); 170 } 171 172 return ret; 173 } 174 175