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
19 MODULE_DESCRIPTION("Synchronous AES cipher using ARMv8 Crypto Extensions");
20 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
21 MODULE_LICENSE("GPL v2");
22
23 struct aes_block {
24 u8 b[AES_BLOCK_SIZE];
25 };
26
27 asmlinkage void __aes_ce_encrypt(u32 *rk, u8 *out, const u8 *in, int rounds);
28 asmlinkage void __aes_ce_decrypt(u32 *rk, u8 *out, const u8 *in, int rounds);
29
30 asmlinkage u32 __aes_ce_sub(u32 l);
31 asmlinkage void __aes_ce_invert(struct aes_block *out,
32 const struct aes_block *in);
33
34 static 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
46 static 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
60 static 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
74 int 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 }
140 EXPORT_SYMBOL(ce_aes_expandkey);
141
142 int 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 }
149 EXPORT_SYMBOL(ce_aes_setkey);
150
151 static 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
168 static int __init aes_mod_init(void)
169 {
170 return crypto_register_alg(&aes_alg);
171 }
172
173 static void __exit aes_mod_exit(void)
174 {
175 crypto_unregister_alg(&aes_alg);
176 }
177
178 module_cpu_feature_match(AES, aes_mod_init);
179 module_exit(aes_mod_exit);
180
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