linux/crypto/aes_ti.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Scalar fixed time AES core transform
   4 *
   5 * Copyright (C) 2017 Linaro Ltd <ard.biesheuvel@linaro.org>
   6 */
   7
   8#include <crypto/aes.h>
   9#include <linux/crypto.h>
  10#include <linux/module.h>
  11
  12static int aesti_set_key(struct crypto_tfm *tfm, const u8 *in_key,
  13                         unsigned int key_len)
  14{
  15        struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
  16
  17        return aes_expandkey(ctx, in_key, key_len);
  18}
  19
  20static void aesti_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
  21{
  22        const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
  23        unsigned long flags;
  24
  25        /*
  26         * Temporarily disable interrupts to avoid races where cachelines are
  27         * evicted when the CPU is interrupted to do something else.
  28         */
  29        local_irq_save(flags);
  30
  31        aes_encrypt(ctx, out, in);
  32
  33        local_irq_restore(flags);
  34}
  35
  36static void aesti_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
  37{
  38        const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
  39        unsigned long flags;
  40
  41        /*
  42         * Temporarily disable interrupts to avoid races where cachelines are
  43         * evicted when the CPU is interrupted to do something else.
  44         */
  45        local_irq_save(flags);
  46
  47        aes_decrypt(ctx, out, in);
  48
  49        local_irq_restore(flags);
  50}
  51
  52static struct crypto_alg aes_alg = {
  53        .cra_name                       = "aes",
  54        .cra_driver_name                = "aes-fixed-time",
  55        .cra_priority                   = 100 + 1,
  56        .cra_flags                      = CRYPTO_ALG_TYPE_CIPHER,
  57        .cra_blocksize                  = AES_BLOCK_SIZE,
  58        .cra_ctxsize                    = sizeof(struct crypto_aes_ctx),
  59        .cra_module                     = THIS_MODULE,
  60
  61        .cra_cipher.cia_min_keysize     = AES_MIN_KEY_SIZE,
  62        .cra_cipher.cia_max_keysize     = AES_MAX_KEY_SIZE,
  63        .cra_cipher.cia_setkey          = aesti_set_key,
  64        .cra_cipher.cia_encrypt         = aesti_encrypt,
  65        .cra_cipher.cia_decrypt         = aesti_decrypt
  66};
  67
  68static int __init aes_init(void)
  69{
  70        return crypto_register_alg(&aes_alg);
  71}
  72
  73static void __exit aes_fini(void)
  74{
  75        crypto_unregister_alg(&aes_alg);
  76}
  77
  78module_init(aes_init);
  79module_exit(aes_fini);
  80
  81MODULE_DESCRIPTION("Generic fixed time AES");
  82MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
  83MODULE_LICENSE("GPL v2");
  84
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