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