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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * aes-ce-cipher.c - core AES cipher using ARMv8 Crypto Extensions
   4  *
   5  * Copyright (C) 2013 - 2017 Linaro Ltd <ard.biesheuvel@linaro.org>
   6  */
   7
   8 #include <asm/neon.h>
   9 #include <asm/simd.h>
  10 #include <asm/unaligned.h>
  11 #include <crypto/aes.h>
  12 #include <crypto/internal/simd.h>
  13 #include <linux/cpufeature.h>
  14 #include <linux/crypto.h>
  15 #include <linux/module.h>
  16
  17 #include "aes-ce-setkey.h"
  18
  19 MODULE_DESCRIPTION("Synchronous AES cipher using ARMv8 Crypto Extensions");
  20 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
  21 MODULE_LICENSE("GPL v2");
  22
  23 struct aes_block {
  24         u8 b[AES_BLOCK_SIZE];
  25 };
  26
  27 asmlinkage void __aes_ce_encrypt(u32 *rk, u8 *out, const u8 *in, int rounds);
  28 asmlinkage void __aes_ce_decrypt(u32 *rk, u8 *out, const u8 *in, int rounds);
  29
  30 asmlinkage u32 __aes_ce_sub(u32 l);
  31 asmlinkage void __aes_ce_invert(struct aes_block *out,
  32                                 const struct aes_block *in);
  33
  34 static int num_rounds(struct crypto_aes_ctx *ctx)
  35 {
  36         /*
  37          * # of rounds specified by AES:
  38          * 128 bit key          10 rounds
  39          * 192 bit key          12 rounds
  40          * 256 bit key          14 rounds
  41          * => n byte key        => 6 + (n/4) rounds
  42          */
  43         return 6 + ctx->key_length / 4;
  44 }
  45
  46 static void aes_cipher_encrypt(struct crypto_tfm *tfm, u8 dst[], u8 const src[])
  47 {
  48         struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
  49
  50         if (!crypto_simd_usable()) {
  51                 aes_encrypt(ctx, dst, src);
  52                 return;
  53         }
  54
  55         kernel_neon_begin();
  56         __aes_ce_encrypt(ctx->key_enc, dst, src, num_rounds(ctx));
  57         kernel_neon_end();
  58 }
  59
  60 static void aes_cipher_decrypt(struct crypto_tfm *tfm, u8 dst[], u8 const src[])
  61 {
  62         struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
  63
  64         if (!crypto_simd_usable()) {
  65                 aes_decrypt(ctx, dst, src);
  66                 return;
  67         }
  68
  69         kernel_neon_begin();
  70         __aes_ce_decrypt(ctx->key_dec, dst, src, num_rounds(ctx));
  71         kernel_neon_end();
  72 }
  73
  74 int ce_aes_expandkey(struct crypto_aes_ctx *ctx, const u8 *in_key,
  75                      unsigned int key_len)
  76 {
  77         /*
  78          * The AES key schedule round constants
  79          */
  80         static u8 const rcon[] = {
  81                 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36,
  82         };
  83
  84         u32 kwords = key_len / sizeof(u32);
  85         struct aes_block *key_enc, *key_dec;
  86         int i, j;
  87
  88         if (key_len != AES_KEYSIZE_128 &&
  89             key_len != AES_KEYSIZE_192 &&
  90             key_len != AES_KEYSIZE_256)
  91                 return -EINVAL;
  92
  93         ctx->key_length = key_len;
  94         for (i = 0; i < kwords; i++)
  95                 ctx->key_enc[i] = get_unaligned_le32(in_key + i * sizeof(u32));
  96
  97         kernel_neon_begin();
  98         for (i = 0; i < sizeof(rcon); i++) {
  99                 u32 *rki = ctx->key_enc + (i * kwords);
 100                 u32 *rko = rki + kwords;
 101
 102                 rko[0] = ror32(__aes_ce_sub(rki[kwords - 1]), 8) ^ rcon[i] ^ rki[0];
 103                 rko[1] = rko[0] ^ rki[1];
 104                 rko[2] = rko[1] ^ rki[2];
 105                 rko[3] = rko[2] ^ rki[3];
 106
 107                 if (key_len == AES_KEYSIZE_192) {
 108                         if (i >= 7)
 109                                 break;
 110                         rko[4] = rko[3] ^ rki[4];
 111                         rko[5] = rko[4] ^ rki[5];
 112                 } else if (key_len == AES_KEYSIZE_256) {
 113                         if (i >= 6)
 114                                 break;
 115                         rko[4] = __aes_ce_sub(rko[3]) ^ rki[4];
 116                         rko[5] = rko[4] ^ rki[5];
 117                         rko[6] = rko[5] ^ rki[6];
 118                         rko[7] = rko[6] ^ rki[7];
 119                 }
 120         }
 121
 122         /*
 123          * Generate the decryption keys for the Equivalent Inverse Cipher.
 124          * This involves reversing the order of the round keys, and applying
 125          * the Inverse Mix Columns transformation on all but the first and
 126          * the last one.
 127          */
 128         key_enc = (struct aes_block *)ctx->key_enc;
 129         key_dec = (struct aes_block *)ctx->key_dec;
 130         j = num_rounds(ctx);
 131
 132         key_dec[0] = key_enc[j];
 133         for (i = 1, j--; j > 0; i++, j--)
 134                 __aes_ce_invert(key_dec + i, key_enc + j);
 135         key_dec[i] = key_enc[0];
 136
 137         kernel_neon_end();
 138         return 0;
 139 }
 140 EXPORT_SYMBOL(ce_aes_expandkey);
 141
 142 int ce_aes_setkey(struct crypto_tfm *tfm, const u8 *in_key,
 143                   unsigned int key_len)
 144 {
 145         struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
 146
 147         return ce_aes_expandkey(ctx, in_key, key_len);
 148 }
 149 EXPORT_SYMBOL(ce_aes_setkey);
 150
 151 static struct crypto_alg aes_alg = {
 152         .cra_name               = "aes",
 153         .cra_driver_name        = "aes-ce",
 154         .cra_priority           = 250,
 155         .cra_flags              = CRYPTO_ALG_TYPE_CIPHER,
 156         .cra_blocksize          = AES_BLOCK_SIZE,
 157         .cra_ctxsize            = sizeof(struct crypto_aes_ctx),
 158         .cra_module             = THIS_MODULE,
 159         .cra_cipher = {
 160                 .cia_min_keysize        = AES_MIN_KEY_SIZE,
 161                 .cia_max_keysize        = AES_MAX_KEY_SIZE,
 162                 .cia_setkey             = ce_aes_setkey,
 163                 .cia_encrypt            = aes_cipher_encrypt,
 164                 .cia_decrypt            = aes_cipher_decrypt
 165         }
 166 };
 167
 168 static int __init aes_mod_init(void)
 169 {
 170         return crypto_register_alg(&aes_alg);
 171 }
 172
 173 static void __exit aes_mod_exit(void)
 174 {
 175         crypto_unregister_alg(&aes_alg);
 176 }
 177
 178 module_cpu_feature_match(AES, aes_mod_init);
 179 module_exit(aes_mod_exit);