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 <assert.h> 19 #include <compiler.h> 20 #include <crypto/crypto.h> 21 #include <initcall.h> 22 #include <kernel/huk_subkey.h> 23 #include <kernel/tee_common_otp.h> 24 #include <kernel/tee_ta_manager.h> 25 #include <stdlib.h> 26 #include <string.h> 27 #include <string_ext.h> 28 #include <tee/tee_cryp_utl.h> 29 #include <tee/tee_fs_key_manager.h> 30 #include <trace.h> 31 #include <util.h> 32 33 struct tee_fs_ssk { 34 bool is_init; 35 uint8_t key[TEE_FS_KM_SSK_SIZE]; 36 }; 37 38 static struct tee_fs_ssk tee_fs_ssk; 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, in_key, in_key_size); 55 if (res != TEE_SUCCESS) 56 goto exit; 57 58 res = crypto_mac_update(ctx, message, message_size); 59 if (res != TEE_SUCCESS) 60 goto exit; 61 62 res = crypto_mac_final(ctx, 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); 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, mode, tsk, sizeof(tsk), NULL, 0, NULL, 0); 114 if (res != TEE_SUCCESS) 115 goto exit; 116 117 res = crypto_cipher_update(ctx, mode, true, in_key, size, dst_key); 118 if (res != TEE_SUCCESS) 119 goto exit; 120 121 crypto_cipher_final(ctx); 122 123 memcpy(out_key, dst_key, sizeof(dst_key)); 124 125 exit: 126 crypto_cipher_free_ctx(ctx); 127 memzero_explicit(tsk, sizeof(tsk)); 128 memzero_explicit(dst_key, sizeof(dst_key)); 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 TEE_Result res = TEE_SUCCESS; 141 142 COMPILE_TIME_ASSERT(TEE_FS_KM_SSK_SIZE <= HUK_SUBKEY_MAX_LEN); 143 144 res = huk_subkey_derive(HUK_SUBKEY_SSK, NULL, 0, 145 tee_fs_ssk.key, sizeof(tee_fs_ssk.key)); 146 if (res == TEE_SUCCESS) { 147 tee_fs_ssk.is_init = 1; 148 } else { 149 memzero_explicit(&tee_fs_ssk, sizeof(tee_fs_ssk)); 150 EMSG("Secure storage will not be available"); 151 } 152 153 return res; 154 } 155 156 TEE_Result tee_fs_generate_fek(const TEE_UUID *uuid, void *buf, size_t buf_size) 157 { 158 TEE_Result res; 159 160 if (buf_size != TEE_FS_KM_FEK_SIZE) 161 return TEE_ERROR_BAD_PARAMETERS; 162 163 res = generate_fek(buf, TEE_FS_KM_FEK_SIZE); 164 if (res != TEE_SUCCESS) 165 return res; 166 167 return tee_fs_fek_crypt(uuid, TEE_MODE_ENCRYPT, buf, 168 TEE_FS_KM_FEK_SIZE, buf); 169 } 170 171 static TEE_Result sha256(uint8_t *out, size_t out_size, const uint8_t *in, 172 size_t in_size) 173 { 174 return tee_hash_createdigest(TEE_ALG_SHA256, in, in_size, 175 out, out_size); 176 } 177 178 static TEE_Result aes_ecb(uint8_t out[TEE_AES_BLOCK_SIZE], 179 const uint8_t in[TEE_AES_BLOCK_SIZE], 180 const uint8_t *key, size_t key_size) 181 { 182 TEE_Result res; 183 void *ctx = NULL; 184 185 res = crypto_cipher_alloc_ctx(&ctx, TEE_ALG_AES_ECB_NOPAD); 186 if (res != TEE_SUCCESS) 187 return res; 188 189 res = crypto_cipher_init(ctx, TEE_MODE_ENCRYPT, key, 190 key_size, NULL, 0, NULL, 0); 191 if (res != TEE_SUCCESS) 192 goto out; 193 194 res = crypto_cipher_update(ctx, TEE_MODE_ENCRYPT, true, in, 195 TEE_AES_BLOCK_SIZE, out); 196 if (res != TEE_SUCCESS) 197 goto out; 198 199 crypto_cipher_final(ctx); 200 res = TEE_SUCCESS; 201 202 out: 203 crypto_cipher_free_ctx(ctx); 204 return res; 205 } 206 207 static TEE_Result essiv(uint8_t iv[TEE_AES_BLOCK_SIZE], 208 const uint8_t fek[TEE_FS_KM_FEK_SIZE], 209 uint16_t blk_idx) 210 { 211 TEE_Result res; 212 uint8_t sha[TEE_SHA256_HASH_SIZE]; 213 uint8_t pad_blkid[TEE_AES_BLOCK_SIZE] = { 0, }; 214 215 res = sha256(sha, sizeof(sha), fek, TEE_FS_KM_FEK_SIZE); 216 if (res != TEE_SUCCESS) 217 return res; 218 219 pad_blkid[0] = (blk_idx & 0xFF); 220 pad_blkid[1] = (blk_idx & 0xFF00) >> 8; 221 222 res = aes_ecb(iv, pad_blkid, sha, 16); 223 224 memzero_explicit(sha, sizeof(sha)); 225 return res; 226 } 227 228 /* 229 * Encryption/decryption of RPMB FS file data. This is AES CBC with ESSIV. 230 */ 231 TEE_Result tee_fs_crypt_block(const TEE_UUID *uuid, uint8_t *out, 232 const uint8_t *in, size_t size, 233 uint16_t blk_idx, const uint8_t *encrypted_fek, 234 TEE_OperationMode mode) 235 { 236 TEE_Result res; 237 uint8_t fek[TEE_FS_KM_FEK_SIZE]; 238 uint8_t iv[TEE_AES_BLOCK_SIZE]; 239 void *ctx; 240 241 DMSG("%scrypt block #%u", (mode == TEE_MODE_ENCRYPT) ? "En" : "De", 242 blk_idx); 243 244 /* Decrypt FEK */ 245 res = tee_fs_fek_crypt(uuid, TEE_MODE_DECRYPT, encrypted_fek, 246 TEE_FS_KM_FEK_SIZE, fek); 247 if (res != TEE_SUCCESS) 248 goto wipe; 249 250 /* Compute initialization vector for this block */ 251 res = essiv(iv, fek, blk_idx); 252 if (res != TEE_SUCCESS) 253 goto wipe; 254 255 /* Run AES CBC */ 256 res = crypto_cipher_alloc_ctx(&ctx, TEE_ALG_AES_CBC_NOPAD); 257 if (res != TEE_SUCCESS) 258 goto wipe; 259 260 res = crypto_cipher_init(ctx, mode, fek, sizeof(fek), NULL, 261 0, iv, TEE_AES_BLOCK_SIZE); 262 if (res != TEE_SUCCESS) 263 goto exit; 264 res = crypto_cipher_update(ctx, mode, true, in, size, out); 265 if (res != TEE_SUCCESS) 266 goto exit; 267 268 crypto_cipher_final(ctx); 269 270 exit: 271 crypto_cipher_free_ctx(ctx); 272 wipe: 273 memzero_explicit(fek, sizeof(fek)); 274 memzero_explicit(iv, sizeof(iv)); 275 return res; 276 } 277 278 service_init_late(tee_fs_init_key_manager); 279