1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Scalar fixed time AES core transform
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright (C) 2017 Linaro Ltd <ard.biesheuvel@linaro.org>
6*4882a593Smuzhiyun */
7*4882a593Smuzhiyun
8*4882a593Smuzhiyun #include <crypto/aes.h>
9*4882a593Smuzhiyun #include <linux/crypto.h>
10*4882a593Smuzhiyun #include <linux/module.h>
11*4882a593Smuzhiyun
aesti_set_key(struct crypto_tfm * tfm,const u8 * in_key,unsigned int key_len)12*4882a593Smuzhiyun static int aesti_set_key(struct crypto_tfm *tfm, const u8 *in_key,
13*4882a593Smuzhiyun unsigned int key_len)
14*4882a593Smuzhiyun {
15*4882a593Smuzhiyun struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
16*4882a593Smuzhiyun
17*4882a593Smuzhiyun return aes_expandkey(ctx, in_key, key_len);
18*4882a593Smuzhiyun }
19*4882a593Smuzhiyun
aesti_encrypt(struct crypto_tfm * tfm,u8 * out,const u8 * in)20*4882a593Smuzhiyun static void aesti_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
21*4882a593Smuzhiyun {
22*4882a593Smuzhiyun const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
23*4882a593Smuzhiyun unsigned long flags;
24*4882a593Smuzhiyun
25*4882a593Smuzhiyun /*
26*4882a593Smuzhiyun * Temporarily disable interrupts to avoid races where cachelines are
27*4882a593Smuzhiyun * evicted when the CPU is interrupted to do something else.
28*4882a593Smuzhiyun */
29*4882a593Smuzhiyun local_irq_save(flags);
30*4882a593Smuzhiyun
31*4882a593Smuzhiyun aes_encrypt(ctx, out, in);
32*4882a593Smuzhiyun
33*4882a593Smuzhiyun local_irq_restore(flags);
34*4882a593Smuzhiyun }
35*4882a593Smuzhiyun
aesti_decrypt(struct crypto_tfm * tfm,u8 * out,const u8 * in)36*4882a593Smuzhiyun static void aesti_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
37*4882a593Smuzhiyun {
38*4882a593Smuzhiyun const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
39*4882a593Smuzhiyun unsigned long flags;
40*4882a593Smuzhiyun
41*4882a593Smuzhiyun /*
42*4882a593Smuzhiyun * Temporarily disable interrupts to avoid races where cachelines are
43*4882a593Smuzhiyun * evicted when the CPU is interrupted to do something else.
44*4882a593Smuzhiyun */
45*4882a593Smuzhiyun local_irq_save(flags);
46*4882a593Smuzhiyun
47*4882a593Smuzhiyun aes_decrypt(ctx, out, in);
48*4882a593Smuzhiyun
49*4882a593Smuzhiyun local_irq_restore(flags);
50*4882a593Smuzhiyun }
51*4882a593Smuzhiyun
52*4882a593Smuzhiyun static struct crypto_alg aes_alg = {
53*4882a593Smuzhiyun .cra_name = "aes",
54*4882a593Smuzhiyun .cra_driver_name = "aes-fixed-time",
55*4882a593Smuzhiyun .cra_priority = 100 + 1,
56*4882a593Smuzhiyun .cra_flags = CRYPTO_ALG_TYPE_CIPHER,
57*4882a593Smuzhiyun .cra_blocksize = AES_BLOCK_SIZE,
58*4882a593Smuzhiyun .cra_ctxsize = sizeof(struct crypto_aes_ctx),
59*4882a593Smuzhiyun .cra_module = THIS_MODULE,
60*4882a593Smuzhiyun
61*4882a593Smuzhiyun .cra_cipher.cia_min_keysize = AES_MIN_KEY_SIZE,
62*4882a593Smuzhiyun .cra_cipher.cia_max_keysize = AES_MAX_KEY_SIZE,
63*4882a593Smuzhiyun .cra_cipher.cia_setkey = aesti_set_key,
64*4882a593Smuzhiyun .cra_cipher.cia_encrypt = aesti_encrypt,
65*4882a593Smuzhiyun .cra_cipher.cia_decrypt = aesti_decrypt
66*4882a593Smuzhiyun };
67*4882a593Smuzhiyun
aes_init(void)68*4882a593Smuzhiyun static int __init aes_init(void)
69*4882a593Smuzhiyun {
70*4882a593Smuzhiyun return crypto_register_alg(&aes_alg);
71*4882a593Smuzhiyun }
72*4882a593Smuzhiyun
aes_fini(void)73*4882a593Smuzhiyun static void __exit aes_fini(void)
74*4882a593Smuzhiyun {
75*4882a593Smuzhiyun crypto_unregister_alg(&aes_alg);
76*4882a593Smuzhiyun }
77*4882a593Smuzhiyun
78*4882a593Smuzhiyun module_init(aes_init);
79*4882a593Smuzhiyun module_exit(aes_fini);
80*4882a593Smuzhiyun
81*4882a593Smuzhiyun MODULE_DESCRIPTION("Generic fixed time AES");
82*4882a593Smuzhiyun MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
83*4882a593Smuzhiyun MODULE_LICENSE("GPL v2");
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