Line data Source code
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 0 : static u32 mul_by_x(u32 w)
92 : {
93 0 : u32 x = w & 0x7f7f7f7f;
94 0 : u32 y = w & 0x80808080;
95 :
96 : /* multiply by polynomial 'x' (0b10) in GF(2^8) */
97 0 : return (x << 1) ^ (y >> 7) * 0x1b;
98 : }
99 :
100 0 : static u32 mul_by_x2(u32 w)
101 : {
102 0 : u32 x = w & 0x3f3f3f3f;
103 0 : u32 y = w & 0x80808080;
104 0 : u32 z = w & 0x40404040;
105 :
106 : /* multiply by polynomial 'x^2' (0b100) in GF(2^8) */
107 0 : return (x << 2) ^ (y >> 7) * 0x36 ^ (z >> 6) * 0x1b;
108 : }
109 :
110 0 : 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 0 : u32 y = mul_by_x(x) ^ ror32(x, 16);
121 :
122 0 : return y ^ ror32(x ^ y, 8);
123 : }
124 :
125 0 : 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 0 : u32 y = mul_by_x2(x);
143 :
144 0 : return mix_columns(x ^ y ^ ror32(y, 16));
145 : }
146 :
147 0 : static __always_inline u32 subshift(u32 in[], int pos)
148 : {
149 0 : return (aes_sbox[in[pos] & 0xff]) ^
150 0 : (aes_sbox[(in[(pos + 1) % 4] >> 8) & 0xff] << 8) ^
151 0 : (aes_sbox[(in[(pos + 2) % 4] >> 16) & 0xff] << 16) ^
152 0 : (aes_sbox[(in[(pos + 3) % 4] >> 24) & 0xff] << 24);
153 : }
154 :
155 0 : static __always_inline u32 inv_subshift(u32 in[], int pos)
156 : {
157 0 : return (aes_inv_sbox[in[pos] & 0xff]) ^
158 0 : (aes_inv_sbox[(in[(pos + 3) % 4] >> 8) & 0xff] << 8) ^
159 0 : (aes_inv_sbox[(in[(pos + 2) % 4] >> 16) & 0xff] << 16) ^
160 0 : (aes_inv_sbox[(in[(pos + 1) % 4] >> 24) & 0xff] << 24);
161 : }
162 :
163 0 : static u32 subw(u32 in)
164 : {
165 0 : return (aes_sbox[in & 0xff]) ^
166 0 : (aes_sbox[(in >> 8) & 0xff] << 8) ^
167 0 : (aes_sbox[(in >> 16) & 0xff] << 16) ^
168 0 : (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 0 : int aes_expandkey(struct crypto_aes_ctx *ctx, const u8 *in_key,
186 : unsigned int key_len)
187 : {
188 0 : u32 kwords = key_len / sizeof(u32);
189 0 : u32 rc, i, j;
190 0 : int err;
191 :
192 0 : err = aes_check_keylen(key_len);
193 0 : if (err)
194 : return err;
195 :
196 0 : ctx->key_length = key_len;
197 :
198 0 : for (i = 0; i < kwords; i++)
199 0 : ctx->key_enc[i] = get_unaligned_le32(in_key + i * sizeof(u32));
200 :
201 0 : for (i = 0, rc = 1; i < 10; i++, rc = mul_by_x(rc)) {
202 0 : u32 *rki = ctx->key_enc + (i * kwords);
203 0 : u32 *rko = rki + kwords;
204 :
205 0 : rko[0] = ror32(subw(rki[kwords - 1]), 8) ^ rc ^ rki[0];
206 0 : rko[1] = rko[0] ^ rki[1];
207 0 : rko[2] = rko[1] ^ rki[2];
208 0 : rko[3] = rko[2] ^ rki[3];
209 :
210 0 : if (key_len == AES_KEYSIZE_192) {
211 0 : if (i >= 7)
212 : break;
213 0 : rko[4] = rko[3] ^ rki[4];
214 0 : rko[5] = rko[4] ^ rki[5];
215 0 : } else if (key_len == AES_KEYSIZE_256) {
216 0 : if (i >= 6)
217 : break;
218 0 : rko[4] = subw(rko[3]) ^ rki[4];
219 0 : rko[5] = rko[4] ^ rki[5];
220 0 : rko[6] = rko[5] ^ rki[6];
221 0 : 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 0 : ctx->key_dec[0] = ctx->key_enc[key_len + 24];
232 0 : ctx->key_dec[1] = ctx->key_enc[key_len + 25];
233 0 : ctx->key_dec[2] = ctx->key_enc[key_len + 26];
234 0 : ctx->key_dec[3] = ctx->key_enc[key_len + 27];
235 :
236 0 : for (i = 4, j = key_len + 20; j > 0; i += 4, j -= 4) {
237 0 : ctx->key_dec[i] = inv_mix_columns(ctx->key_enc[j]);
238 0 : ctx->key_dec[i + 1] = inv_mix_columns(ctx->key_enc[j + 1]);
239 0 : ctx->key_dec[i + 2] = inv_mix_columns(ctx->key_enc[j + 2]);
240 0 : ctx->key_dec[i + 3] = inv_mix_columns(ctx->key_enc[j + 3]);
241 : }
242 :
243 0 : ctx->key_dec[i] = ctx->key_enc[0];
244 0 : ctx->key_dec[i + 1] = ctx->key_enc[1];
245 0 : ctx->key_dec[i + 2] = ctx->key_enc[2];
246 0 : ctx->key_dec[i + 3] = ctx->key_enc[3];
247 :
248 0 : 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 0 : void aes_encrypt(const struct crypto_aes_ctx *ctx, u8 *out, const u8 *in)
259 : {
260 0 : const u32 *rkp = ctx->key_enc + 4;
261 0 : int rounds = 6 + ctx->key_length / 4;
262 0 : u32 st0[4], st1[4];
263 0 : int round;
264 :
265 0 : st0[0] = ctx->key_enc[0] ^ get_unaligned_le32(in);
266 0 : st0[1] = ctx->key_enc[1] ^ get_unaligned_le32(in + 4);
267 0 : st0[2] = ctx->key_enc[2] ^ get_unaligned_le32(in + 8);
268 0 : st0[3] = ctx->key_enc[3] ^ get_unaligned_le32(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 0 : st0[0] ^= aes_sbox[ 0] ^ aes_sbox[ 64] ^ aes_sbox[134] ^ aes_sbox[195];
277 0 : st0[1] ^= aes_sbox[16] ^ aes_sbox[ 82] ^ aes_sbox[158] ^ aes_sbox[221];
278 0 : st0[2] ^= aes_sbox[32] ^ aes_sbox[ 96] ^ aes_sbox[160] ^ aes_sbox[234];
279 0 : st0[3] ^= aes_sbox[48] ^ aes_sbox[112] ^ aes_sbox[186] ^ aes_sbox[241];
280 :
281 0 : for (round = 0;; round += 2, rkp += 8) {
282 0 : st1[0] = mix_columns(subshift(st0, 0)) ^ rkp[0];
283 0 : st1[1] = mix_columns(subshift(st0, 1)) ^ rkp[1];
284 0 : st1[2] = mix_columns(subshift(st0, 2)) ^ rkp[2];
285 0 : st1[3] = mix_columns(subshift(st0, 3)) ^ rkp[3];
286 :
287 0 : if (round == rounds - 2)
288 : break;
289 :
290 0 : st0[0] = mix_columns(subshift(st1, 0)) ^ rkp[4];
291 0 : st0[1] = mix_columns(subshift(st1, 1)) ^ rkp[5];
292 0 : st0[2] = mix_columns(subshift(st1, 2)) ^ rkp[6];
293 0 : st0[3] = mix_columns(subshift(st1, 3)) ^ rkp[7];
294 : }
295 :
296 0 : put_unaligned_le32(subshift(st1, 0) ^ rkp[4], out);
297 0 : put_unaligned_le32(subshift(st1, 1) ^ rkp[5], out + 4);
298 0 : put_unaligned_le32(subshift(st1, 2) ^ rkp[6], out + 8);
299 0 : put_unaligned_le32(subshift(st1, 3) ^ rkp[7], out + 12);
300 0 : }
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 0 : void aes_decrypt(const struct crypto_aes_ctx *ctx, u8 *out, const u8 *in)
310 : {
311 0 : const u32 *rkp = ctx->key_dec + 4;
312 0 : int rounds = 6 + ctx->key_length / 4;
313 0 : u32 st0[4], st1[4];
314 0 : int round;
315 :
316 0 : st0[0] = ctx->key_dec[0] ^ get_unaligned_le32(in);
317 0 : st0[1] = ctx->key_dec[1] ^ get_unaligned_le32(in + 4);
318 0 : st0[2] = ctx->key_dec[2] ^ get_unaligned_le32(in + 8);
319 0 : st0[3] = ctx->key_dec[3] ^ get_unaligned_le32(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 0 : st0[0] ^= aes_inv_sbox[ 0] ^ aes_inv_sbox[ 64] ^ aes_inv_sbox[129] ^ aes_inv_sbox[200];
328 0 : st0[1] ^= aes_inv_sbox[16] ^ aes_inv_sbox[ 83] ^ aes_inv_sbox[150] ^ aes_inv_sbox[212];
329 0 : st0[2] ^= aes_inv_sbox[32] ^ aes_inv_sbox[ 96] ^ aes_inv_sbox[160] ^ aes_inv_sbox[236];
330 0 : st0[3] ^= aes_inv_sbox[48] ^ aes_inv_sbox[112] ^ aes_inv_sbox[187] ^ aes_inv_sbox[247];
331 :
332 0 : for (round = 0;; round += 2, rkp += 8) {
333 0 : st1[0] = inv_mix_columns(inv_subshift(st0, 0)) ^ rkp[0];
334 0 : st1[1] = inv_mix_columns(inv_subshift(st0, 1)) ^ rkp[1];
335 0 : st1[2] = inv_mix_columns(inv_subshift(st0, 2)) ^ rkp[2];
336 0 : st1[3] = inv_mix_columns(inv_subshift(st0, 3)) ^ rkp[3];
337 :
338 0 : if (round == rounds - 2)
339 : break;
340 :
341 0 : st0[0] = inv_mix_columns(inv_subshift(st1, 0)) ^ rkp[4];
342 0 : st0[1] = inv_mix_columns(inv_subshift(st1, 1)) ^ rkp[5];
343 0 : st0[2] = inv_mix_columns(inv_subshift(st1, 2)) ^ rkp[6];
344 0 : st0[3] = inv_mix_columns(inv_subshift(st1, 3)) ^ rkp[7];
345 : }
346 :
347 0 : put_unaligned_le32(inv_subshift(st1, 0) ^ rkp[4], out);
348 0 : put_unaligned_le32(inv_subshift(st1, 1) ^ rkp[5], out + 4);
349 0 : put_unaligned_le32(inv_subshift(st1, 2) ^ rkp[6], out + 8);
350 0 : put_unaligned_le32(inv_subshift(st1, 3) ^ rkp[7], out + 12);
351 0 : }
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");
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