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 <crypto/algapi.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