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 <linux/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, out: dst, in: src);
52 return;
53 }
54
55 scoped_ksimd()
56 __aes_ce_encrypt(rk: ctx->key_enc, out: dst, in: src, rounds: num_rounds(ctx));
57}
58
59static void aes_cipher_decrypt(struct crypto_tfm *tfm, u8 dst[], u8 const src[])
60{
61 struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
62
63 if (!crypto_simd_usable()) {
64 aes_decrypt(ctx, out: dst, in: src);
65 return;
66 }
67
68 scoped_ksimd()
69 __aes_ce_decrypt(rk: ctx->key_dec, out: dst, in: src, rounds: num_rounds(ctx));
70}
71
72int ce_aes_expandkey(struct crypto_aes_ctx *ctx, const u8 *in_key,
73 unsigned int key_len)
74{
75 /*
76 * The AES key schedule round constants
77 */
78 static u8 const rcon[] = {
79 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36,
80 };
81
82 u32 kwords = key_len / sizeof(u32);
83 struct aes_block *key_enc, *key_dec;
84 int i, j;
85
86 if (key_len != AES_KEYSIZE_128 &&
87 key_len != AES_KEYSIZE_192 &&
88 key_len != AES_KEYSIZE_256)
89 return -EINVAL;
90
91 ctx->key_length = key_len;
92 for (i = 0; i < kwords; i++)
93 ctx->key_enc[i] = get_unaligned_le32(p: in_key + i * sizeof(u32));
94
95 scoped_ksimd() {
96 for (i = 0; i < sizeof(rcon); i++) {
97 u32 *rki = ctx->key_enc + (i * kwords);
98 u32 *rko = rki + kwords;
99
100 rko[0] = ror32(word: __aes_ce_sub(l: rki[kwords - 1]), shift: 8) ^
101 rcon[i] ^ rki[0];
102 rko[1] = rko[0] ^ rki[1];
103 rko[2] = rko[1] ^ rki[2];
104 rko[3] = rko[2] ^ rki[3];
105
106 if (key_len == AES_KEYSIZE_192) {
107 if (i >= 7)
108 break;
109 rko[4] = rko[3] ^ rki[4];
110 rko[5] = rko[4] ^ rki[5];
111 } else if (key_len == AES_KEYSIZE_256) {
112 if (i >= 6)
113 break;
114 rko[4] = __aes_ce_sub(l: rko[3]) ^ rki[4];
115 rko[5] = rko[4] ^ rki[5];
116 rko[6] = rko[5] ^ rki[6];
117 rko[7] = rko[6] ^ rki[7];
118 }
119 }
120
121 /*
122 * Generate the decryption keys for the Equivalent Inverse
123 * Cipher. This involves reversing the order of the round
124 * keys, and applying the Inverse Mix Columns transformation on
125 * all but the first and the last one.
126 */
127 key_enc = (struct aes_block *)ctx->key_enc;
128 key_dec = (struct aes_block *)ctx->key_dec;
129 j = num_rounds(ctx);
130
131 key_dec[0] = key_enc[j];
132 for (i = 1, j--; j > 0; i++, j--)
133 __aes_ce_invert(out: key_dec + i, in: key_enc + j);
134 key_dec[i] = key_enc[0];
135 }
136
137 return 0;
138}
139EXPORT_SYMBOL(ce_aes_expandkey);
140
141int ce_aes_setkey(struct crypto_tfm *tfm, const u8 *in_key,
142 unsigned int key_len)
143{
144 struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
145
146 return ce_aes_expandkey(ctx, in_key, key_len);
147}
148EXPORT_SYMBOL(ce_aes_setkey);
149
150static struct crypto_alg aes_alg = {
151 .cra_name = "aes",
152 .cra_driver_name = "aes-ce",
153 .cra_priority = 250,
154 .cra_flags = CRYPTO_ALG_TYPE_CIPHER,
155 .cra_blocksize = AES_BLOCK_SIZE,
156 .cra_ctxsize = sizeof(struct crypto_aes_ctx),
157 .cra_module = THIS_MODULE,
158 .cra_cipher = {
159 .cia_min_keysize = AES_MIN_KEY_SIZE,
160 .cia_max_keysize = AES_MAX_KEY_SIZE,
161 .cia_setkey = ce_aes_setkey,
162 .cia_encrypt = aes_cipher_encrypt,
163 .cia_decrypt = aes_cipher_decrypt
164 }
165};
166
167static int __init aes_mod_init(void)
168{
169 return crypto_register_alg(alg: &aes_alg);
170}
171
172static void __exit aes_mod_exit(void)
173{
174 crypto_unregister_alg(alg: &aes_alg);
175}
176
177module_cpu_feature_match(AES, aes_mod_init);
178module_exit(aes_mod_exit);
179

source code of linux/arch/arm64/crypto/aes-ce-glue.c