1 // SPDX-License-Identifier: BSD-2-Clause 2 /* 3 * Copyright (c) 2015, Linaro Limited 4 */ 5 6 7 /* 8 * Acronyms: 9 * 10 * FEK - File Encryption Key 11 * SSK - Secure Storage Key 12 * TSK - Trusted app Storage Key 13 * IV - Initial vector 14 * HUK - Hardware Unique Key 15 * RNG - Random Number Generator 16 */ 17 18 #include <compiler.h> 19 #include <crypto/crypto.h> 20 #include <initcall.h> 21 #include <kernel/panic.h> 22 #include <kernel/tee_common_otp.h> 23 #include <kernel/tee_ta_manager.h> 24 #include <stdlib.h> 25 #include <string.h> 26 #include <tee/tee_cryp_utl.h> 27 #include <tee/tee_fs_key_manager.h> 28 #include <trace.h> 29 #include <util.h> 30 31 struct tee_fs_ssk { 32 bool is_init; 33 uint8_t key[TEE_FS_KM_SSK_SIZE]; 34 }; 35 36 static struct tee_fs_ssk tee_fs_ssk; 37 static uint8_t string_for_ssk_gen[] = "ONLY_FOR_tee_fs_ssk"; 38 39 40 static TEE_Result do_hmac(void *out_key, size_t out_key_size, 41 const void *in_key, size_t in_key_size, 42 const void *message, size_t message_size) 43 { 44 TEE_Result res; 45 void *ctx = NULL; 46 47 if (!out_key || !in_key || !message) 48 return TEE_ERROR_BAD_PARAMETERS; 49 50 res = crypto_mac_alloc_ctx(&ctx, TEE_FS_KM_HMAC_ALG); 51 if (res != TEE_SUCCESS) 52 return res; 53 54 res = crypto_mac_init(ctx, TEE_FS_KM_HMAC_ALG, in_key, in_key_size); 55 if (res != TEE_SUCCESS) 56 goto exit; 57 58 res = crypto_mac_update(ctx, TEE_FS_KM_HMAC_ALG, message, message_size); 59 if (res != TEE_SUCCESS) 60 goto exit; 61 62 res = crypto_mac_final(ctx, TEE_FS_KM_HMAC_ALG, out_key, out_key_size); 63 if (res != TEE_SUCCESS) 64 goto exit; 65 66 res = TEE_SUCCESS; 67 68 exit: 69 crypto_mac_free_ctx(ctx, TEE_FS_KM_HMAC_ALG); 70 return res; 71 } 72 73 TEE_Result tee_fs_fek_crypt(const TEE_UUID *uuid, TEE_OperationMode mode, 74 const uint8_t *in_key, size_t size, 75 uint8_t *out_key) 76 { 77 TEE_Result res; 78 void *ctx = NULL; 79 uint8_t tsk[TEE_FS_KM_TSK_SIZE]; 80 uint8_t dst_key[size]; 81 82 if (!in_key || !out_key) 83 return TEE_ERROR_BAD_PARAMETERS; 84 85 if (size != TEE_FS_KM_FEK_SIZE) 86 return TEE_ERROR_BAD_PARAMETERS; 87 88 if (tee_fs_ssk.is_init == 0) 89 return TEE_ERROR_GENERIC; 90 91 if (uuid) { 92 res = do_hmac(tsk, sizeof(tsk), tee_fs_ssk.key, 93 TEE_FS_KM_SSK_SIZE, uuid, sizeof(*uuid)); 94 if (res != TEE_SUCCESS) 95 return res; 96 } else { 97 /* 98 * Pick something of a different size than TEE_UUID to 99 * guarantee that there's never a conflict. 100 */ 101 uint8_t dummy[1] = { 0 }; 102 103 res = do_hmac(tsk, sizeof(tsk), tee_fs_ssk.key, 104 TEE_FS_KM_SSK_SIZE, dummy, sizeof(dummy)); 105 if (res != TEE_SUCCESS) 106 return res; 107 } 108 109 res = crypto_cipher_alloc_ctx(&ctx, TEE_FS_KM_ENC_FEK_ALG); 110 if (res != TEE_SUCCESS) 111 return res; 112 113 res = crypto_cipher_init(ctx, TEE_FS_KM_ENC_FEK_ALG, mode, tsk, 114 sizeof(tsk), NULL, 0, NULL, 0); 115 if (res != TEE_SUCCESS) 116 goto exit; 117 118 res = crypto_cipher_update(ctx, TEE_FS_KM_ENC_FEK_ALG, 119 mode, true, in_key, size, dst_key); 120 if (res != TEE_SUCCESS) 121 goto exit; 122 123 crypto_cipher_final(ctx, TEE_FS_KM_ENC_FEK_ALG); 124 125 memcpy(out_key, dst_key, sizeof(dst_key)); 126 127 exit: 128 crypto_cipher_free_ctx(ctx, TEE_FS_KM_ENC_FEK_ALG); 129 130 return res; 131 } 132 133 static TEE_Result generate_fek(uint8_t *key, uint8_t len) 134 { 135 return crypto_rng_read(key, len); 136 } 137 138 static TEE_Result tee_fs_init_key_manager(void) 139 { 140 int res = TEE_SUCCESS; 141 struct tee_hw_unique_key huk; 142 uint8_t chip_id[TEE_FS_KM_CHIP_ID_LENGTH]; 143 uint8_t message[sizeof(chip_id) + sizeof(string_for_ssk_gen)]; 144 145 /* Secure Storage Key Generation: 146 * 147 * SSK = HMAC(HUK, message) 148 * message := concatenate(chip_id, static string) 149 * */ 150 tee_otp_get_hw_unique_key(&huk); 151 tee_otp_get_die_id(chip_id, sizeof(chip_id)); 152 153 memcpy(message, chip_id, sizeof(chip_id)); 154 memcpy(message + sizeof(chip_id), string_for_ssk_gen, 155 sizeof(string_for_ssk_gen)); 156 157 res = do_hmac(tee_fs_ssk.key, sizeof(tee_fs_ssk.key), 158 huk.data, sizeof(huk.data), 159 message, sizeof(message)); 160 161 if (res == TEE_SUCCESS) 162 tee_fs_ssk.is_init = 1; 163 164 return res; 165 } 166 167 TEE_Result tee_fs_generate_fek(const TEE_UUID *uuid, void *buf, size_t buf_size) 168 { 169 TEE_Result res; 170 171 if (buf_size != TEE_FS_KM_FEK_SIZE) 172 return TEE_ERROR_BAD_PARAMETERS; 173 174 res = generate_fek(buf, TEE_FS_KM_FEK_SIZE); 175 if (res != TEE_SUCCESS) 176 return res; 177 178 return tee_fs_fek_crypt(uuid, TEE_MODE_ENCRYPT, buf, 179 TEE_FS_KM_FEK_SIZE, buf); 180 } 181 182 static TEE_Result sha256(uint8_t *out, size_t out_size, const uint8_t *in, 183 size_t in_size) 184 { 185 return tee_hash_createdigest(TEE_ALG_SHA256, in, in_size, 186 out, out_size); 187 } 188 189 static TEE_Result aes_ecb(uint8_t out[TEE_AES_BLOCK_SIZE], 190 const uint8_t in[TEE_AES_BLOCK_SIZE], 191 const uint8_t *key, size_t key_size) 192 { 193 TEE_Result res; 194 void *ctx = NULL; 195 const uint32_t algo = TEE_ALG_AES_ECB_NOPAD; 196 197 res = crypto_cipher_alloc_ctx(&ctx, algo); 198 if (res != TEE_SUCCESS) 199 return res; 200 201 res = crypto_cipher_init(ctx, algo, TEE_MODE_ENCRYPT, key, 202 key_size, NULL, 0, NULL, 0); 203 if (res != TEE_SUCCESS) 204 goto out; 205 206 res = crypto_cipher_update(ctx, algo, TEE_MODE_ENCRYPT, true, in, 207 TEE_AES_BLOCK_SIZE, out); 208 if (res != TEE_SUCCESS) 209 goto out; 210 211 crypto_cipher_final(ctx, algo); 212 res = TEE_SUCCESS; 213 214 out: 215 crypto_cipher_free_ctx(ctx, algo); 216 return res; 217 } 218 219 static TEE_Result essiv(uint8_t iv[TEE_AES_BLOCK_SIZE], 220 const uint8_t fek[TEE_FS_KM_FEK_SIZE], 221 uint16_t blk_idx) 222 { 223 TEE_Result res; 224 uint8_t sha[TEE_SHA256_HASH_SIZE]; 225 uint8_t pad_blkid[TEE_AES_BLOCK_SIZE] = { 0, }; 226 227 res = sha256(sha, sizeof(sha), fek, TEE_FS_KM_FEK_SIZE); 228 if (res != TEE_SUCCESS) 229 return res; 230 231 pad_blkid[0] = (blk_idx & 0xFF); 232 pad_blkid[1] = (blk_idx & 0xFF00) >> 8; 233 234 return aes_ecb(iv, pad_blkid, sha, 16); 235 } 236 237 /* 238 * Encryption/decryption of RPMB FS file data. This is AES CBC with ESSIV. 239 */ 240 TEE_Result tee_fs_crypt_block(const TEE_UUID *uuid, uint8_t *out, 241 const uint8_t *in, size_t size, 242 uint16_t blk_idx, const uint8_t *encrypted_fek, 243 TEE_OperationMode mode) 244 { 245 TEE_Result res; 246 uint8_t fek[TEE_FS_KM_FEK_SIZE]; 247 uint8_t iv[TEE_AES_BLOCK_SIZE]; 248 void *ctx; 249 const uint32_t algo = TEE_ALG_AES_CBC_NOPAD; 250 251 DMSG("%scrypt block #%u", (mode == TEE_MODE_ENCRYPT) ? "En" : "De", 252 blk_idx); 253 254 /* Decrypt FEK */ 255 res = tee_fs_fek_crypt(uuid, TEE_MODE_DECRYPT, encrypted_fek, 256 TEE_FS_KM_FEK_SIZE, fek); 257 if (res != TEE_SUCCESS) 258 return res; 259 260 /* Compute initialization vector for this block */ 261 res = essiv(iv, fek, blk_idx); 262 263 /* Run AES CBC */ 264 res = crypto_cipher_alloc_ctx(&ctx, algo); 265 if (res != TEE_SUCCESS) 266 return res; 267 268 res = crypto_cipher_init(ctx, algo, mode, fek, sizeof(fek), NULL, 269 0, iv, TEE_AES_BLOCK_SIZE); 270 if (res != TEE_SUCCESS) 271 goto exit; 272 res = crypto_cipher_update(ctx, algo, mode, true, in, size, out); 273 if (res != TEE_SUCCESS) 274 goto exit; 275 276 crypto_cipher_final(ctx, algo); 277 278 exit: 279 crypto_cipher_free_ctx(ctx, algo); 280 return res; 281 } 282 283 service_init_late(tee_fs_init_key_manager); 284