1 /* 2 * aes-ce-cipher.c - core AES cipher using ARMv8 Crypto Extensions 3 * 4 * Copyright (C) 2013 - 2017 Linaro Ltd <ard.biesheuvel@linaro.org> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 */ 10 11 #include <asm/neon.h> 12 #include <asm/simd.h> 13 #include <asm/unaligned.h> 14 #include <crypto/aes.h> 15 #include <linux/cpufeature.h> 16 #include <linux/crypto.h> 17 #include <linux/module.h> 18 19 #include "aes-ce-setkey.h" 20 21 MODULE_DESCRIPTION("Synchronous AES cipher using ARMv8 Crypto Extensions"); 22 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>"); 23 MODULE_LICENSE("GPL v2"); 24 25 asmlinkage void __aes_arm64_encrypt(u32 *rk, u8 *out, const u8 *in, int rounds); 26 asmlinkage void __aes_arm64_decrypt(u32 *rk, u8 *out, const u8 *in, int rounds); 27 28 struct aes_block { 29 u8 b[AES_BLOCK_SIZE]; 30 }; 31 32 asmlinkage void __aes_ce_encrypt(u32 *rk, u8 *out, const u8 *in, int rounds); 33 asmlinkage void __aes_ce_decrypt(u32 *rk, u8 *out, const u8 *in, int rounds); 34 35 asmlinkage u32 __aes_ce_sub(u32 l); 36 asmlinkage void __aes_ce_invert(struct aes_block *out, 37 const struct aes_block *in); 38 39 static int num_rounds(struct crypto_aes_ctx *ctx) 40 { 41 /* 42 * # of rounds specified by AES: 43 * 128 bit key 10 rounds 44 * 192 bit key 12 rounds 45 * 256 bit key 14 rounds 46 * => n byte key => 6 + (n/4) rounds 47 */ 48 return 6 + ctx->key_length / 4; 49 } 50 51 static void aes_cipher_encrypt(struct crypto_tfm *tfm, u8 dst[], u8 const src[]) 52 { 53 struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm); 54 55 if (!may_use_simd()) { 56 __aes_arm64_encrypt(ctx->key_enc, dst, src, num_rounds(ctx)); 57 return; 58 } 59 60 kernel_neon_begin(); 61 __aes_ce_encrypt(ctx->key_enc, dst, src, num_rounds(ctx)); 62 kernel_neon_end(); 63 } 64 65 static void aes_cipher_decrypt(struct crypto_tfm *tfm, u8 dst[], u8 const src[]) 66 { 67 struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm); 68 69 if (!may_use_simd()) { 70 __aes_arm64_decrypt(ctx->key_dec, dst, src, num_rounds(ctx)); 71 return; 72 } 73 74 kernel_neon_begin(); 75 __aes_ce_decrypt(ctx->key_dec, dst, src, num_rounds(ctx)); 76 kernel_neon_end(); 77 } 78 79 int ce_aes_expandkey(struct crypto_aes_ctx *ctx, const u8 *in_key, 80 unsigned int key_len) 81 { 82 /* 83 * The AES key schedule round constants 84 */ 85 static u8 const rcon[] = { 86 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 87 }; 88 89 u32 kwords = key_len / sizeof(u32); 90 struct aes_block *key_enc, *key_dec; 91 int i, j; 92 93 if (key_len != AES_KEYSIZE_128 && 94 key_len != AES_KEYSIZE_192 && 95 key_len != AES_KEYSIZE_256) 96 return -EINVAL; 97 98 ctx->key_length = key_len; 99 for (i = 0; i < kwords; i++) 100 ctx->key_enc[i] = get_unaligned_le32(in_key + i * sizeof(u32)); 101 102 kernel_neon_begin(); 103 for (i = 0; i < sizeof(rcon); i++) { 104 u32 *rki = ctx->key_enc + (i * kwords); 105 u32 *rko = rki + kwords; 106 107 rko[0] = ror32(__aes_ce_sub(rki[kwords - 1]), 8) ^ rcon[i] ^ rki[0]; 108 rko[1] = rko[0] ^ rki[1]; 109 rko[2] = rko[1] ^ rki[2]; 110 rko[3] = rko[2] ^ rki[3]; 111 112 if (key_len == AES_KEYSIZE_192) { 113 if (i >= 7) 114 break; 115 rko[4] = rko[3] ^ rki[4]; 116 rko[5] = rko[4] ^ rki[5]; 117 } else if (key_len == AES_KEYSIZE_256) { 118 if (i >= 6) 119 break; 120 rko[4] = __aes_ce_sub(rko[3]) ^ rki[4]; 121 rko[5] = rko[4] ^ rki[5]; 122 rko[6] = rko[5] ^ rki[6]; 123 rko[7] = rko[6] ^ rki[7]; 124 } 125 } 126 127 /* 128 * Generate the decryption keys for the Equivalent Inverse Cipher. 129 * This involves reversing the order of the round keys, and applying 130 * the Inverse Mix Columns transformation on all but the first and 131 * the last one. 132 */ 133 key_enc = (struct aes_block *)ctx->key_enc; 134 key_dec = (struct aes_block *)ctx->key_dec; 135 j = num_rounds(ctx); 136 137 key_dec[0] = key_enc[j]; 138 for (i = 1, j--; j > 0; i++, j--) 139 __aes_ce_invert(key_dec + i, key_enc + j); 140 key_dec[i] = key_enc[0]; 141 142 kernel_neon_end(); 143 return 0; 144 } 145 EXPORT_SYMBOL(ce_aes_expandkey); 146 147 int ce_aes_setkey(struct crypto_tfm *tfm, const u8 *in_key, 148 unsigned int key_len) 149 { 150 struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm); 151 int ret; 152 153 ret = ce_aes_expandkey(ctx, in_key, key_len); 154 if (!ret) 155 return 0; 156 157 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN; 158 return -EINVAL; 159 } 160 EXPORT_SYMBOL(ce_aes_setkey); 161 162 static struct crypto_alg aes_alg = { 163 .cra_name = "aes", 164 .cra_driver_name = "aes-ce", 165 .cra_priority = 250, 166 .cra_flags = CRYPTO_ALG_TYPE_CIPHER, 167 .cra_blocksize = AES_BLOCK_SIZE, 168 .cra_ctxsize = sizeof(struct crypto_aes_ctx), 169 .cra_module = THIS_MODULE, 170 .cra_cipher = { 171 .cia_min_keysize = AES_MIN_KEY_SIZE, 172 .cia_max_keysize = AES_MAX_KEY_SIZE, 173 .cia_setkey = ce_aes_setkey, 174 .cia_encrypt = aes_cipher_encrypt, 175 .cia_decrypt = aes_cipher_decrypt 176 } 177 }; 178 179 static int __init aes_mod_init(void) 180 { 181 return crypto_register_alg(&aes_alg); 182 } 183 184 static void __exit aes_mod_exit(void) 185 { 186 crypto_unregister_alg(&aes_alg); 187 } 188 189 module_cpu_feature_match(AES, aes_mod_init); 190 module_exit(aes_mod_exit); 191