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
aesti_set_key(struct crypto_tfm * tfm,const u8 * in_key,unsigned int key_len)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
aesti_encrypt(struct crypto_tfm * tfm,u8 * out,const u8 * in)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
aesti_decrypt(struct crypto_tfm * tfm,u8 * out,const u8 * in)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
aes_init(void)68 static int __init aes_init(void)
69 {
70 return crypto_register_alg(&aes_alg);
71 }
72
aes_fini(void)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");
84