arch/arm64/crypto/aes-ce-glue.c

   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);