crypto/aes_ti.c

   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
  12 static 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
  20 static 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
  36 static 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
  52 static 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
  68 static int __init aes_init(void)
  69 {
  70         return crypto_register_alg(&aes_alg);
  71 }
  72
  73 static void __exit aes_fini(void)
  74 {
  75         crypto_unregister_alg(&aes_alg);
  76 }
  77
  78 module_init(aes_init);
  79 module_exit(aes_fini);
  80
  81 MODULE_DESCRIPTION("Generic fixed time AES");
  82 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
  83 MODULE_LICENSE("GPL v2");