1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * aes-ce-cipher.c - core AES cipher using ARMv8 Crypto Extensions
4 *
5 * Copyright (C) 2013 - 2017 Linaro Ltd <ard.biesheuvel@linaro.org>
6 */
7
8#include <asm/neon.h>
9#include <asm/simd.h>
10#include <asm/unaligned.h>
11#include <crypto/aes.h>
12#include <crypto/algapi.h>
13#include <crypto/internal/simd.h>
14#include <linux/cpufeature.h>
15#include <linux/module.h>
16
17#include "aes-ce-setkey.h"
18
19MODULE_DESCRIPTION("Synchronous AES cipher using ARMv8 Crypto Extensions");
20MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
21MODULE_LICENSE("GPL v2");
22
23struct aes_block {
24	u8 b[AES_BLOCK_SIZE];
25};
26
27asmlinkage void __aes_ce_encrypt(u32 *rk, u8 *out, const u8 *in, int rounds);
28asmlinkage void __aes_ce_decrypt(u32 *rk, u8 *out, const u8 *in, int rounds);
29
30asmlinkage u32 __aes_ce_sub(u32 l);
31asmlinkage void __aes_ce_invert(struct aes_block *out,
32				const struct aes_block *in);
33
34static int num_rounds(struct crypto_aes_ctx *ctx)
35{
36	/*
37	 * # of rounds specified by AES:
38	 * 128 bit key		10 rounds
39	 * 192 bit key		12 rounds
40	 * 256 bit key		14 rounds
41	 * => n byte key	=> 6 + (n/4) rounds
42	 */
43	return 6 + ctx->key_length / 4;
44}
45
46static void aes_cipher_encrypt(struct crypto_tfm *tfm, u8 dst[], u8 const src[])
47{
48	struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
49
50	if (!crypto_simd_usable()) {
51		aes_encrypt(ctx, dst, src);
52		return;
53	}
54
55	kernel_neon_begin();
56	__aes_ce_encrypt(ctx->key_enc, dst, src, num_rounds(ctx));
57	kernel_neon_end();
58}
59
60static void aes_cipher_decrypt(struct crypto_tfm *tfm, u8 dst[], u8 const src[])
61{
62	struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
63
64	if (!crypto_simd_usable()) {
65		aes_decrypt(ctx, dst, src);
66		return;
67	}
68
69	kernel_neon_begin();
70	__aes_ce_decrypt(ctx->key_dec, dst, src, num_rounds(ctx));
71	kernel_neon_end();
72}
73
74int ce_aes_expandkey(struct crypto_aes_ctx *ctx, const u8 *in_key,
75		     unsigned int key_len)
76{
77	/*
78	 * The AES key schedule round constants
79	 */
80	static u8 const rcon[] = {
81		0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36,
82	};
83
84	u32 kwords = key_len / sizeof(u32);
85	struct aes_block *key_enc, *key_dec;
86	int i, j;
87
88	if (key_len != AES_KEYSIZE_128 &&
89	    key_len != AES_KEYSIZE_192 &&
90	    key_len != AES_KEYSIZE_256)
91		return -EINVAL;
92
93	ctx->key_length = key_len;
94	for (i = 0; i < kwords; i++)
95		ctx->key_enc[i] = get_unaligned_le32(in_key + i * sizeof(u32));
96
97	kernel_neon_begin();
98	for (i = 0; i < sizeof(rcon); i++) {
99		u32 *rki = ctx->key_enc + (i * kwords);
100		u32 *rko = rki + kwords;
101
102		rko[0] = ror32(__aes_ce_sub(rki[kwords - 1]), 8) ^ rcon[i] ^ rki[0];
103		rko[1] = rko[0] ^ rki[1];
104		rko[2] = rko[1] ^ rki[2];
105		rko[3] = rko[2] ^ rki[3];
106
107		if (key_len == AES_KEYSIZE_192) {
108			if (i >= 7)
109				break;
110			rko[4] = rko[3] ^ rki[4];
111			rko[5] = rko[4] ^ rki[5];
112		} else if (key_len == AES_KEYSIZE_256) {
113			if (i >= 6)
114				break;
115			rko[4] = __aes_ce_sub(rko[3]) ^ rki[4];
116			rko[5] = rko[4] ^ rki[5];
117			rko[6] = rko[5] ^ rki[6];
118			rko[7] = rko[6] ^ rki[7];
119		}
120	}
121
122	/*
123	 * Generate the decryption keys for the Equivalent Inverse Cipher.
124	 * This involves reversing the order of the round keys, and applying
125	 * the Inverse Mix Columns transformation on all but the first and
126	 * the last one.
127	 */
128	key_enc = (struct aes_block *)ctx->key_enc;
129	key_dec = (struct aes_block *)ctx->key_dec;
130	j = num_rounds(ctx);
131
132	key_dec[0] = key_enc[j];
133	for (i = 1, j--; j > 0; i++, j--)
134		__aes_ce_invert(key_dec + i, key_enc + j);
135	key_dec[i] = key_enc[0];
136
137	kernel_neon_end();
138	return 0;
139}
140EXPORT_SYMBOL(ce_aes_expandkey);
141
142int ce_aes_setkey(struct crypto_tfm *tfm, const u8 *in_key,
143		  unsigned int key_len)
144{
145	struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
146
147	return ce_aes_expandkey(ctx, in_key, key_len);
148}
149EXPORT_SYMBOL(ce_aes_setkey);
150
151static struct crypto_alg aes_alg = {
152	.cra_name		= "aes",
153	.cra_driver_name	= "aes-ce",
154	.cra_priority		= 250,
155	.cra_flags		= CRYPTO_ALG_TYPE_CIPHER,
156	.cra_blocksize		= AES_BLOCK_SIZE,
157	.cra_ctxsize		= sizeof(struct crypto_aes_ctx),
158	.cra_module		= THIS_MODULE,
159	.cra_cipher = {
160		.cia_min_keysize	= AES_MIN_KEY_SIZE,
161		.cia_max_keysize	= AES_MAX_KEY_SIZE,
162		.cia_setkey		= ce_aes_setkey,
163		.cia_encrypt		= aes_cipher_encrypt,
164		.cia_decrypt		= aes_cipher_decrypt
165	}
166};
167
168static int __init aes_mod_init(void)
169{
170	return crypto_register_alg(&aes_alg);
171}
172
173static void __exit aes_mod_exit(void)
174{
175	crypto_unregister_alg(&aes_alg);
176}
177
178module_cpu_feature_match(AES, aes_mod_init);
179module_exit(aes_mod_exit);
180