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/internal/simd.h>
13 #include <linux/cpufeature.h>
14 #include <linux/crypto.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 
num_rounds(struct crypto_aes_ctx * ctx)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 
aes_cipher_encrypt(struct crypto_tfm * tfm,u8 dst[],u8 const src[])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 
aes_cipher_decrypt(struct crypto_tfm * tfm,u8 dst[],u8 const src[])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 
ce_aes_expandkey(struct crypto_aes_ctx * ctx,const u8 * in_key,unsigned int key_len)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 
ce_aes_setkey(struct crypto_tfm * tfm,const u8 * in_key,unsigned int key_len)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 
aes_mod_init(void)168 static int __init aes_mod_init(void)
169 {
170 	return crypto_register_alg(&aes_alg);
171 }
172 
aes_mod_exit(void)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