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