1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * Copyright (C) 2017-2019 Linaro Ltd <ard.biesheuvel@linaro.org> |
4 | */ |
5 | |
6 | #include <crypto/aes.h> |
7 | #include <linux/crypto.h> |
8 | #include <linux/module.h> |
9 | #include <asm/unaligned.h> |
10 | |
11 | /* |
12 | * Emit the sbox as volatile const to prevent the compiler from doing |
13 | * constant folding on sbox references involving fixed indexes. |
14 | */ |
15 | static volatile const u8 __cacheline_aligned aes_sbox[] = { |
16 | 0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, |
17 | 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76, |
18 | 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, |
19 | 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0, |
20 | 0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, |
21 | 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15, |
22 | 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, |
23 | 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75, |
24 | 0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, |
25 | 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84, |
26 | 0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, |
27 | 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf, |
28 | 0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, |
29 | 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8, |
30 | 0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, |
31 | 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2, |
32 | 0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, |
33 | 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73, |
34 | 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, |
35 | 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb, |
36 | 0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, |
37 | 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79, |
38 | 0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, |
39 | 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08, |
40 | 0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, |
41 | 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a, |
42 | 0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, |
43 | 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e, |
44 | 0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, |
45 | 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf, |
46 | 0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, |
47 | 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16, |
48 | }; |
49 | |
50 | static volatile const u8 __cacheline_aligned aes_inv_sbox[] = { |
51 | 0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, |
52 | 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb, |
53 | 0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, |
54 | 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb, |
55 | 0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, |
56 | 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e, |
57 | 0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, |
58 | 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25, |
59 | 0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, |
60 | 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92, |
61 | 0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, |
62 | 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84, |
63 | 0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, |
64 | 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06, |
65 | 0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, |
66 | 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b, |
67 | 0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, |
68 | 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73, |
69 | 0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, |
70 | 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e, |
71 | 0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, |
72 | 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b, |
73 | 0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, |
74 | 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4, |
75 | 0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, |
76 | 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f, |
77 | 0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, |
78 | 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef, |
79 | 0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, |
80 | 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61, |
81 | 0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, |
82 | 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d, |
83 | }; |
84 | |
85 | extern const u8 crypto_aes_sbox[256] __alias(aes_sbox); |
86 | extern const u8 crypto_aes_inv_sbox[256] __alias(aes_inv_sbox); |
87 | |
88 | EXPORT_SYMBOL(crypto_aes_sbox); |
89 | EXPORT_SYMBOL(crypto_aes_inv_sbox); |
90 | |
91 | static u32 mul_by_x(u32 w) |
92 | { |
93 | u32 x = w & 0x7f7f7f7f; |
94 | u32 y = w & 0x80808080; |
95 | |
96 | /* multiply by polynomial 'x' (0b10) in GF(2^8) */ |
97 | return (x << 1) ^ (y >> 7) * 0x1b; |
98 | } |
99 | |
100 | static u32 mul_by_x2(u32 w) |
101 | { |
102 | u32 x = w & 0x3f3f3f3f; |
103 | u32 y = w & 0x80808080; |
104 | u32 z = w & 0x40404040; |
105 | |
106 | /* multiply by polynomial 'x^2' (0b100) in GF(2^8) */ |
107 | return (x << 2) ^ (y >> 7) * 0x36 ^ (z >> 6) * 0x1b; |
108 | } |
109 | |
110 | static u32 mix_columns(u32 x) |
111 | { |
112 | /* |
113 | * Perform the following matrix multiplication in GF(2^8) |
114 | * |
115 | * | 0x2 0x3 0x1 0x1 | | x[0] | |
116 | * | 0x1 0x2 0x3 0x1 | | x[1] | |
117 | * | 0x1 0x1 0x2 0x3 | x | x[2] | |
118 | * | 0x3 0x1 0x1 0x2 | | x[3] | |
119 | */ |
120 | u32 y = mul_by_x(w: x) ^ ror32(word: x, shift: 16); |
121 | |
122 | return y ^ ror32(word: x ^ y, shift: 8); |
123 | } |
124 | |
125 | static u32 inv_mix_columns(u32 x) |
126 | { |
127 | /* |
128 | * Perform the following matrix multiplication in GF(2^8) |
129 | * |
130 | * | 0xe 0xb 0xd 0x9 | | x[0] | |
131 | * | 0x9 0xe 0xb 0xd | | x[1] | |
132 | * | 0xd 0x9 0xe 0xb | x | x[2] | |
133 | * | 0xb 0xd 0x9 0xe | | x[3] | |
134 | * |
135 | * which can conveniently be reduced to |
136 | * |
137 | * | 0x2 0x3 0x1 0x1 | | 0x5 0x0 0x4 0x0 | | x[0] | |
138 | * | 0x1 0x2 0x3 0x1 | | 0x0 0x5 0x0 0x4 | | x[1] | |
139 | * | 0x1 0x1 0x2 0x3 | x | 0x4 0x0 0x5 0x0 | x | x[2] | |
140 | * | 0x3 0x1 0x1 0x2 | | 0x0 0x4 0x0 0x5 | | x[3] | |
141 | */ |
142 | u32 y = mul_by_x2(w: x); |
143 | |
144 | return mix_columns(x: x ^ y ^ ror32(word: y, shift: 16)); |
145 | } |
146 | |
147 | static __always_inline u32 subshift(u32 in[], int pos) |
148 | { |
149 | return (aes_sbox[in[pos] & 0xff]) ^ |
150 | (aes_sbox[(in[(pos + 1) % 4] >> 8) & 0xff] << 8) ^ |
151 | (aes_sbox[(in[(pos + 2) % 4] >> 16) & 0xff] << 16) ^ |
152 | (aes_sbox[(in[(pos + 3) % 4] >> 24) & 0xff] << 24); |
153 | } |
154 | |
155 | static __always_inline u32 inv_subshift(u32 in[], int pos) |
156 | { |
157 | return (aes_inv_sbox[in[pos] & 0xff]) ^ |
158 | (aes_inv_sbox[(in[(pos + 3) % 4] >> 8) & 0xff] << 8) ^ |
159 | (aes_inv_sbox[(in[(pos + 2) % 4] >> 16) & 0xff] << 16) ^ |
160 | (aes_inv_sbox[(in[(pos + 1) % 4] >> 24) & 0xff] << 24); |
161 | } |
162 | |
163 | static u32 subw(u32 in) |
164 | { |
165 | return (aes_sbox[in & 0xff]) ^ |
166 | (aes_sbox[(in >> 8) & 0xff] << 8) ^ |
167 | (aes_sbox[(in >> 16) & 0xff] << 16) ^ |
168 | (aes_sbox[(in >> 24) & 0xff] << 24); |
169 | } |
170 | |
171 | /** |
172 | * aes_expandkey - Expands the AES key as described in FIPS-197 |
173 | * @ctx: The location where the computed key will be stored. |
174 | * @in_key: The supplied key. |
175 | * @key_len: The length of the supplied key. |
176 | * |
177 | * Returns 0 on success. The function fails only if an invalid key size (or |
178 | * pointer) is supplied. |
179 | * The expanded key size is 240 bytes (max of 14 rounds with a unique 16 bytes |
180 | * key schedule plus a 16 bytes key which is used before the first round). |
181 | * The decryption key is prepared for the "Equivalent Inverse Cipher" as |
182 | * described in FIPS-197. The first slot (16 bytes) of each key (enc or dec) is |
183 | * for the initial combination, the second slot for the first round and so on. |
184 | */ |
185 | int aes_expandkey(struct crypto_aes_ctx *ctx, const u8 *in_key, |
186 | unsigned int key_len) |
187 | { |
188 | u32 kwords = key_len / sizeof(u32); |
189 | u32 rc, i, j; |
190 | int err; |
191 | |
192 | err = aes_check_keylen(keylen: key_len); |
193 | if (err) |
194 | return err; |
195 | |
196 | ctx->key_length = key_len; |
197 | |
198 | for (i = 0; i < kwords; i++) |
199 | ctx->key_enc[i] = get_unaligned_le32(p: in_key + i * sizeof(u32)); |
200 | |
201 | for (i = 0, rc = 1; i < 10; i++, rc = mul_by_x(w: rc)) { |
202 | u32 *rki = ctx->key_enc + (i * kwords); |
203 | u32 *rko = rki + kwords; |
204 | |
205 | rko[0] = ror32(word: subw(in: rki[kwords - 1]), shift: 8) ^ rc ^ rki[0]; |
206 | rko[1] = rko[0] ^ rki[1]; |
207 | rko[2] = rko[1] ^ rki[2]; |
208 | rko[3] = rko[2] ^ rki[3]; |
209 | |
210 | if (key_len == AES_KEYSIZE_192) { |
211 | if (i >= 7) |
212 | break; |
213 | rko[4] = rko[3] ^ rki[4]; |
214 | rko[5] = rko[4] ^ rki[5]; |
215 | } else if (key_len == AES_KEYSIZE_256) { |
216 | if (i >= 6) |
217 | break; |
218 | rko[4] = subw(in: rko[3]) ^ rki[4]; |
219 | rko[5] = rko[4] ^ rki[5]; |
220 | rko[6] = rko[5] ^ rki[6]; |
221 | rko[7] = rko[6] ^ rki[7]; |
222 | } |
223 | } |
224 | |
225 | /* |
226 | * Generate the decryption keys for the Equivalent Inverse Cipher. |
227 | * This involves reversing the order of the round keys, and applying |
228 | * the Inverse Mix Columns transformation to all but the first and |
229 | * the last one. |
230 | */ |
231 | ctx->key_dec[0] = ctx->key_enc[key_len + 24]; |
232 | ctx->key_dec[1] = ctx->key_enc[key_len + 25]; |
233 | ctx->key_dec[2] = ctx->key_enc[key_len + 26]; |
234 | ctx->key_dec[3] = ctx->key_enc[key_len + 27]; |
235 | |
236 | for (i = 4, j = key_len + 20; j > 0; i += 4, j -= 4) { |
237 | ctx->key_dec[i] = inv_mix_columns(x: ctx->key_enc[j]); |
238 | ctx->key_dec[i + 1] = inv_mix_columns(x: ctx->key_enc[j + 1]); |
239 | ctx->key_dec[i + 2] = inv_mix_columns(x: ctx->key_enc[j + 2]); |
240 | ctx->key_dec[i + 3] = inv_mix_columns(x: ctx->key_enc[j + 3]); |
241 | } |
242 | |
243 | ctx->key_dec[i] = ctx->key_enc[0]; |
244 | ctx->key_dec[i + 1] = ctx->key_enc[1]; |
245 | ctx->key_dec[i + 2] = ctx->key_enc[2]; |
246 | ctx->key_dec[i + 3] = ctx->key_enc[3]; |
247 | |
248 | return 0; |
249 | } |
250 | EXPORT_SYMBOL(aes_expandkey); |
251 | |
252 | /** |
253 | * aes_encrypt - Encrypt a single AES block |
254 | * @ctx: Context struct containing the key schedule |
255 | * @out: Buffer to store the ciphertext |
256 | * @in: Buffer containing the plaintext |
257 | */ |
258 | void aes_encrypt(const struct crypto_aes_ctx *ctx, u8 *out, const u8 *in) |
259 | { |
260 | const u32 *rkp = ctx->key_enc + 4; |
261 | int rounds = 6 + ctx->key_length / 4; |
262 | u32 st0[4], st1[4]; |
263 | int round; |
264 | |
265 | st0[0] = ctx->key_enc[0] ^ get_unaligned_le32(p: in); |
266 | st0[1] = ctx->key_enc[1] ^ get_unaligned_le32(p: in + 4); |
267 | st0[2] = ctx->key_enc[2] ^ get_unaligned_le32(p: in + 8); |
268 | st0[3] = ctx->key_enc[3] ^ get_unaligned_le32(p: in + 12); |
269 | |
270 | /* |
271 | * Force the compiler to emit data independent Sbox references, |
272 | * by xoring the input with Sbox values that are known to add up |
273 | * to zero. This pulls the entire Sbox into the D-cache before any |
274 | * data dependent lookups are done. |
275 | */ |
276 | st0[0] ^= aes_sbox[ 0] ^ aes_sbox[ 64] ^ aes_sbox[134] ^ aes_sbox[195]; |
277 | st0[1] ^= aes_sbox[16] ^ aes_sbox[ 82] ^ aes_sbox[158] ^ aes_sbox[221]; |
278 | st0[2] ^= aes_sbox[32] ^ aes_sbox[ 96] ^ aes_sbox[160] ^ aes_sbox[234]; |
279 | st0[3] ^= aes_sbox[48] ^ aes_sbox[112] ^ aes_sbox[186] ^ aes_sbox[241]; |
280 | |
281 | for (round = 0;; round += 2, rkp += 8) { |
282 | st1[0] = mix_columns(x: subshift(in: st0, pos: 0)) ^ rkp[0]; |
283 | st1[1] = mix_columns(x: subshift(in: st0, pos: 1)) ^ rkp[1]; |
284 | st1[2] = mix_columns(x: subshift(in: st0, pos: 2)) ^ rkp[2]; |
285 | st1[3] = mix_columns(x: subshift(in: st0, pos: 3)) ^ rkp[3]; |
286 | |
287 | if (round == rounds - 2) |
288 | break; |
289 | |
290 | st0[0] = mix_columns(x: subshift(in: st1, pos: 0)) ^ rkp[4]; |
291 | st0[1] = mix_columns(x: subshift(in: st1, pos: 1)) ^ rkp[5]; |
292 | st0[2] = mix_columns(x: subshift(in: st1, pos: 2)) ^ rkp[6]; |
293 | st0[3] = mix_columns(x: subshift(in: st1, pos: 3)) ^ rkp[7]; |
294 | } |
295 | |
296 | put_unaligned_le32(val: subshift(in: st1, pos: 0) ^ rkp[4], p: out); |
297 | put_unaligned_le32(val: subshift(in: st1, pos: 1) ^ rkp[5], p: out + 4); |
298 | put_unaligned_le32(val: subshift(in: st1, pos: 2) ^ rkp[6], p: out + 8); |
299 | put_unaligned_le32(val: subshift(in: st1, pos: 3) ^ rkp[7], p: out + 12); |
300 | } |
301 | EXPORT_SYMBOL(aes_encrypt); |
302 | |
303 | /** |
304 | * aes_decrypt - Decrypt a single AES block |
305 | * @ctx: Context struct containing the key schedule |
306 | * @out: Buffer to store the plaintext |
307 | * @in: Buffer containing the ciphertext |
308 | */ |
309 | void aes_decrypt(const struct crypto_aes_ctx *ctx, u8 *out, const u8 *in) |
310 | { |
311 | const u32 *rkp = ctx->key_dec + 4; |
312 | int rounds = 6 + ctx->key_length / 4; |
313 | u32 st0[4], st1[4]; |
314 | int round; |
315 | |
316 | st0[0] = ctx->key_dec[0] ^ get_unaligned_le32(p: in); |
317 | st0[1] = ctx->key_dec[1] ^ get_unaligned_le32(p: in + 4); |
318 | st0[2] = ctx->key_dec[2] ^ get_unaligned_le32(p: in + 8); |
319 | st0[3] = ctx->key_dec[3] ^ get_unaligned_le32(p: in + 12); |
320 | |
321 | /* |
322 | * Force the compiler to emit data independent Sbox references, |
323 | * by xoring the input with Sbox values that are known to add up |
324 | * to zero. This pulls the entire Sbox into the D-cache before any |
325 | * data dependent lookups are done. |
326 | */ |
327 | st0[0] ^= aes_inv_sbox[ 0] ^ aes_inv_sbox[ 64] ^ aes_inv_sbox[129] ^ aes_inv_sbox[200]; |
328 | st0[1] ^= aes_inv_sbox[16] ^ aes_inv_sbox[ 83] ^ aes_inv_sbox[150] ^ aes_inv_sbox[212]; |
329 | st0[2] ^= aes_inv_sbox[32] ^ aes_inv_sbox[ 96] ^ aes_inv_sbox[160] ^ aes_inv_sbox[236]; |
330 | st0[3] ^= aes_inv_sbox[48] ^ aes_inv_sbox[112] ^ aes_inv_sbox[187] ^ aes_inv_sbox[247]; |
331 | |
332 | for (round = 0;; round += 2, rkp += 8) { |
333 | st1[0] = inv_mix_columns(x: inv_subshift(in: st0, pos: 0)) ^ rkp[0]; |
334 | st1[1] = inv_mix_columns(x: inv_subshift(in: st0, pos: 1)) ^ rkp[1]; |
335 | st1[2] = inv_mix_columns(x: inv_subshift(in: st0, pos: 2)) ^ rkp[2]; |
336 | st1[3] = inv_mix_columns(x: inv_subshift(in: st0, pos: 3)) ^ rkp[3]; |
337 | |
338 | if (round == rounds - 2) |
339 | break; |
340 | |
341 | st0[0] = inv_mix_columns(x: inv_subshift(in: st1, pos: 0)) ^ rkp[4]; |
342 | st0[1] = inv_mix_columns(x: inv_subshift(in: st1, pos: 1)) ^ rkp[5]; |
343 | st0[2] = inv_mix_columns(x: inv_subshift(in: st1, pos: 2)) ^ rkp[6]; |
344 | st0[3] = inv_mix_columns(x: inv_subshift(in: st1, pos: 3)) ^ rkp[7]; |
345 | } |
346 | |
347 | put_unaligned_le32(val: inv_subshift(in: st1, pos: 0) ^ rkp[4], p: out); |
348 | put_unaligned_le32(val: inv_subshift(in: st1, pos: 1) ^ rkp[5], p: out + 4); |
349 | put_unaligned_le32(val: inv_subshift(in: st1, pos: 2) ^ rkp[6], p: out + 8); |
350 | put_unaligned_le32(val: inv_subshift(in: st1, pos: 3) ^ rkp[7], p: out + 12); |
351 | } |
352 | EXPORT_SYMBOL(aes_decrypt); |
353 | |
354 | MODULE_DESCRIPTION("Generic AES library" ); |
355 | MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>" ); |
356 | MODULE_LICENSE("GPL v2" ); |
357 | |