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 #include <trace/hooks/fips140.h>
11
12 /*
13 * Emit the sbox as volatile const to prevent the compiler from doing
14 * constant folding on sbox references involving fixed indexes.
15 */
16 static volatile const u8 __cacheline_aligned aes_sbox[] = {
17 0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5,
18 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
19 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0,
20 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
21 0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc,
22 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
23 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a,
24 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
25 0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0,
26 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
27 0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b,
28 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
29 0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85,
30 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
31 0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5,
32 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
33 0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17,
34 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
35 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88,
36 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
37 0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c,
38 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
39 0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9,
40 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
41 0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6,
42 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
43 0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e,
44 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
45 0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94,
46 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
47 0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68,
48 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16,
49 };
50
51 static volatile const u8 __cacheline_aligned aes_inv_sbox[] = {
52 0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38,
53 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
54 0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87,
55 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
56 0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d,
57 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
58 0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2,
59 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
60 0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16,
61 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
62 0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda,
63 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
64 0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a,
65 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
66 0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02,
67 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
68 0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea,
69 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
70 0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85,
71 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
72 0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89,
73 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
74 0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20,
75 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
76 0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31,
77 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
78 0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d,
79 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
80 0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0,
81 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
82 0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26,
83 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d,
84 };
85
86 extern const u8 crypto_aes_sbox[256] __alias(aes_sbox);
87 extern const u8 crypto_aes_inv_sbox[256] __alias(aes_inv_sbox);
88
89 EXPORT_SYMBOL(crypto_aes_sbox);
90 EXPORT_SYMBOL(crypto_aes_inv_sbox);
91
mul_by_x(u32 w)92 static u32 mul_by_x(u32 w)
93 {
94 u32 x = w & 0x7f7f7f7f;
95 u32 y = w & 0x80808080;
96
97 /* multiply by polynomial 'x' (0b10) in GF(2^8) */
98 return (x << 1) ^ (y >> 7) * 0x1b;
99 }
100
mul_by_x2(u32 w)101 static u32 mul_by_x2(u32 w)
102 {
103 u32 x = w & 0x3f3f3f3f;
104 u32 y = w & 0x80808080;
105 u32 z = w & 0x40404040;
106
107 /* multiply by polynomial 'x^2' (0b100) in GF(2^8) */
108 return (x << 2) ^ (y >> 7) * 0x36 ^ (z >> 6) * 0x1b;
109 }
110
mix_columns(u32 x)111 static u32 mix_columns(u32 x)
112 {
113 /*
114 * Perform the following matrix multiplication in GF(2^8)
115 *
116 * | 0x2 0x3 0x1 0x1 | | x[0] |
117 * | 0x1 0x2 0x3 0x1 | | x[1] |
118 * | 0x1 0x1 0x2 0x3 | x | x[2] |
119 * | 0x3 0x1 0x1 0x2 | | x[3] |
120 */
121 u32 y = mul_by_x(x) ^ ror32(x, 16);
122
123 return y ^ ror32(x ^ y, 8);
124 }
125
inv_mix_columns(u32 x)126 static u32 inv_mix_columns(u32 x)
127 {
128 /*
129 * Perform the following matrix multiplication in GF(2^8)
130 *
131 * | 0xe 0xb 0xd 0x9 | | x[0] |
132 * | 0x9 0xe 0xb 0xd | | x[1] |
133 * | 0xd 0x9 0xe 0xb | x | x[2] |
134 * | 0xb 0xd 0x9 0xe | | x[3] |
135 *
136 * which can conveniently be reduced to
137 *
138 * | 0x2 0x3 0x1 0x1 | | 0x5 0x0 0x4 0x0 | | x[0] |
139 * | 0x1 0x2 0x3 0x1 | | 0x0 0x5 0x0 0x4 | | x[1] |
140 * | 0x1 0x1 0x2 0x3 | x | 0x4 0x0 0x5 0x0 | x | x[2] |
141 * | 0x3 0x1 0x1 0x2 | | 0x0 0x4 0x0 0x5 | | x[3] |
142 */
143 u32 y = mul_by_x2(x);
144
145 return mix_columns(x ^ y ^ ror32(y, 16));
146 }
147
subshift(u32 in[],int pos)148 static __always_inline u32 subshift(u32 in[], int pos)
149 {
150 return (aes_sbox[in[pos] & 0xff]) ^
151 (aes_sbox[(in[(pos + 1) % 4] >> 8) & 0xff] << 8) ^
152 (aes_sbox[(in[(pos + 2) % 4] >> 16) & 0xff] << 16) ^
153 (aes_sbox[(in[(pos + 3) % 4] >> 24) & 0xff] << 24);
154 }
155
inv_subshift(u32 in[],int pos)156 static __always_inline u32 inv_subshift(u32 in[], int pos)
157 {
158 return (aes_inv_sbox[in[pos] & 0xff]) ^
159 (aes_inv_sbox[(in[(pos + 3) % 4] >> 8) & 0xff] << 8) ^
160 (aes_inv_sbox[(in[(pos + 2) % 4] >> 16) & 0xff] << 16) ^
161 (aes_inv_sbox[(in[(pos + 1) % 4] >> 24) & 0xff] << 24);
162 }
163
subw(u32 in)164 static u32 subw(u32 in)
165 {
166 return (aes_sbox[in & 0xff]) ^
167 (aes_sbox[(in >> 8) & 0xff] << 8) ^
168 (aes_sbox[(in >> 16) & 0xff] << 16) ^
169 (aes_sbox[(in >> 24) & 0xff] << 24);
170 }
171
172 /**
173 * aes_expandkey - Expands the AES key as described in FIPS-197
174 * @ctx: The location where the computed key will be stored.
175 * @in_key: The supplied key.
176 * @key_len: The length of the supplied key.
177 *
178 * Returns 0 on success. The function fails only if an invalid key size (or
179 * pointer) is supplied.
180 * The expanded key size is 240 bytes (max of 14 rounds with a unique 16 bytes
181 * key schedule plus a 16 bytes key which is used before the first round).
182 * The decryption key is prepared for the "Equivalent Inverse Cipher" as
183 * described in FIPS-197. The first slot (16 bytes) of each key (enc or dec) is
184 * for the initial combination, the second slot for the first round and so on.
185 */
aes_expandkey(struct crypto_aes_ctx * ctx,const u8 * in_key,unsigned int key_len)186 int aes_expandkey(struct crypto_aes_ctx *ctx, const u8 *in_key,
187 unsigned int key_len)
188 {
189 u32 kwords = key_len / sizeof(u32);
190 u32 rc, i, j;
191 int err;
192
193 #ifndef __DISABLE_EXPORTS
194 err = -(MAX_ERRNO + 1);
195 trace_android_vh_aes_expandkey(ctx, in_key, key_len, &err);
196 if (err != -(MAX_ERRNO + 1))
197 return err;
198 #endif
199
200 err = aes_check_keylen(key_len);
201 if (err)
202 return err;
203
204 ctx->key_length = key_len;
205
206 for (i = 0; i < kwords; i++)
207 ctx->key_enc[i] = get_unaligned_le32(in_key + i * sizeof(u32));
208
209 for (i = 0, rc = 1; i < 10; i++, rc = mul_by_x(rc)) {
210 u32 *rki = ctx->key_enc + (i * kwords);
211 u32 *rko = rki + kwords;
212
213 rko[0] = ror32(subw(rki[kwords - 1]), 8) ^ rc ^ rki[0];
214 rko[1] = rko[0] ^ rki[1];
215 rko[2] = rko[1] ^ rki[2];
216 rko[3] = rko[2] ^ rki[3];
217
218 if (key_len == AES_KEYSIZE_192) {
219 if (i >= 7)
220 break;
221 rko[4] = rko[3] ^ rki[4];
222 rko[5] = rko[4] ^ rki[5];
223 } else if (key_len == AES_KEYSIZE_256) {
224 if (i >= 6)
225 break;
226 rko[4] = subw(rko[3]) ^ rki[4];
227 rko[5] = rko[4] ^ rki[5];
228 rko[6] = rko[5] ^ rki[6];
229 rko[7] = rko[6] ^ rki[7];
230 }
231 }
232
233 /*
234 * Generate the decryption keys for the Equivalent Inverse Cipher.
235 * This involves reversing the order of the round keys, and applying
236 * the Inverse Mix Columns transformation to all but the first and
237 * the last one.
238 */
239 ctx->key_dec[0] = ctx->key_enc[key_len + 24];
240 ctx->key_dec[1] = ctx->key_enc[key_len + 25];
241 ctx->key_dec[2] = ctx->key_enc[key_len + 26];
242 ctx->key_dec[3] = ctx->key_enc[key_len + 27];
243
244 for (i = 4, j = key_len + 20; j > 0; i += 4, j -= 4) {
245 ctx->key_dec[i] = inv_mix_columns(ctx->key_enc[j]);
246 ctx->key_dec[i + 1] = inv_mix_columns(ctx->key_enc[j + 1]);
247 ctx->key_dec[i + 2] = inv_mix_columns(ctx->key_enc[j + 2]);
248 ctx->key_dec[i + 3] = inv_mix_columns(ctx->key_enc[j + 3]);
249 }
250
251 ctx->key_dec[i] = ctx->key_enc[0];
252 ctx->key_dec[i + 1] = ctx->key_enc[1];
253 ctx->key_dec[i + 2] = ctx->key_enc[2];
254 ctx->key_dec[i + 3] = ctx->key_enc[3];
255
256 return 0;
257 }
258 EXPORT_SYMBOL(aes_expandkey);
259
260 /**
261 * aes_encrypt - Encrypt a single AES block
262 * @ctx: Context struct containing the key schedule
263 * @out: Buffer to store the ciphertext
264 * @in: Buffer containing the plaintext
265 */
aes_encrypt(const struct crypto_aes_ctx * ctx,u8 * out,const u8 * in)266 void aes_encrypt(const struct crypto_aes_ctx *ctx, u8 *out, const u8 *in)
267 {
268 const u32 *rkp = ctx->key_enc + 4;
269 int rounds = 6 + ctx->key_length / 4;
270 u32 st0[4], st1[4];
271 int round;
272 #ifndef __DISABLE_EXPORTS
273 int hook_inuse = 0;
274
275 trace_android_vh_aes_encrypt(ctx, out, in, &hook_inuse);
276 if (hook_inuse)
277 return;
278 #endif
279
280 st0[0] = ctx->key_enc[0] ^ get_unaligned_le32(in);
281 st0[1] = ctx->key_enc[1] ^ get_unaligned_le32(in + 4);
282 st0[2] = ctx->key_enc[2] ^ get_unaligned_le32(in + 8);
283 st0[3] = ctx->key_enc[3] ^ get_unaligned_le32(in + 12);
284
285 /*
286 * Force the compiler to emit data independent Sbox references,
287 * by xoring the input with Sbox values that are known to add up
288 * to zero. This pulls the entire Sbox into the D-cache before any
289 * data dependent lookups are done.
290 */
291 st0[0] ^= aes_sbox[ 0] ^ aes_sbox[ 64] ^ aes_sbox[134] ^ aes_sbox[195];
292 st0[1] ^= aes_sbox[16] ^ aes_sbox[ 82] ^ aes_sbox[158] ^ aes_sbox[221];
293 st0[2] ^= aes_sbox[32] ^ aes_sbox[ 96] ^ aes_sbox[160] ^ aes_sbox[234];
294 st0[3] ^= aes_sbox[48] ^ aes_sbox[112] ^ aes_sbox[186] ^ aes_sbox[241];
295
296 for (round = 0;; round += 2, rkp += 8) {
297 st1[0] = mix_columns(subshift(st0, 0)) ^ rkp[0];
298 st1[1] = mix_columns(subshift(st0, 1)) ^ rkp[1];
299 st1[2] = mix_columns(subshift(st0, 2)) ^ rkp[2];
300 st1[3] = mix_columns(subshift(st0, 3)) ^ rkp[3];
301
302 if (round == rounds - 2)
303 break;
304
305 st0[0] = mix_columns(subshift(st1, 0)) ^ rkp[4];
306 st0[1] = mix_columns(subshift(st1, 1)) ^ rkp[5];
307 st0[2] = mix_columns(subshift(st1, 2)) ^ rkp[6];
308 st0[3] = mix_columns(subshift(st1, 3)) ^ rkp[7];
309 }
310
311 put_unaligned_le32(subshift(st1, 0) ^ rkp[4], out);
312 put_unaligned_le32(subshift(st1, 1) ^ rkp[5], out + 4);
313 put_unaligned_le32(subshift(st1, 2) ^ rkp[6], out + 8);
314 put_unaligned_le32(subshift(st1, 3) ^ rkp[7], out + 12);
315 }
316 EXPORT_SYMBOL(aes_encrypt);
317
318 /**
319 * aes_decrypt - Decrypt a single AES block
320 * @ctx: Context struct containing the key schedule
321 * @out: Buffer to store the plaintext
322 * @in: Buffer containing the ciphertext
323 */
aes_decrypt(const struct crypto_aes_ctx * ctx,u8 * out,const u8 * in)324 void aes_decrypt(const struct crypto_aes_ctx *ctx, u8 *out, const u8 *in)
325 {
326 const u32 *rkp = ctx->key_dec + 4;
327 int rounds = 6 + ctx->key_length / 4;
328 u32 st0[4], st1[4];
329 int round;
330 #ifndef __DISABLE_EXPORTS
331 int hook_inuse = 0;
332
333 trace_android_vh_aes_decrypt(ctx, out, in, &hook_inuse);
334 if (hook_inuse)
335 return;
336 #endif
337
338 st0[0] = ctx->key_dec[0] ^ get_unaligned_le32(in);
339 st0[1] = ctx->key_dec[1] ^ get_unaligned_le32(in + 4);
340 st0[2] = ctx->key_dec[2] ^ get_unaligned_le32(in + 8);
341 st0[3] = ctx->key_dec[3] ^ get_unaligned_le32(in + 12);
342
343 /*
344 * Force the compiler to emit data independent Sbox references,
345 * by xoring the input with Sbox values that are known to add up
346 * to zero. This pulls the entire Sbox into the D-cache before any
347 * data dependent lookups are done.
348 */
349 st0[0] ^= aes_inv_sbox[ 0] ^ aes_inv_sbox[ 64] ^ aes_inv_sbox[129] ^ aes_inv_sbox[200];
350 st0[1] ^= aes_inv_sbox[16] ^ aes_inv_sbox[ 83] ^ aes_inv_sbox[150] ^ aes_inv_sbox[212];
351 st0[2] ^= aes_inv_sbox[32] ^ aes_inv_sbox[ 96] ^ aes_inv_sbox[160] ^ aes_inv_sbox[236];
352 st0[3] ^= aes_inv_sbox[48] ^ aes_inv_sbox[112] ^ aes_inv_sbox[187] ^ aes_inv_sbox[247];
353
354 for (round = 0;; round += 2, rkp += 8) {
355 st1[0] = inv_mix_columns(inv_subshift(st0, 0)) ^ rkp[0];
356 st1[1] = inv_mix_columns(inv_subshift(st0, 1)) ^ rkp[1];
357 st1[2] = inv_mix_columns(inv_subshift(st0, 2)) ^ rkp[2];
358 st1[3] = inv_mix_columns(inv_subshift(st0, 3)) ^ rkp[3];
359
360 if (round == rounds - 2)
361 break;
362
363 st0[0] = inv_mix_columns(inv_subshift(st1, 0)) ^ rkp[4];
364 st0[1] = inv_mix_columns(inv_subshift(st1, 1)) ^ rkp[5];
365 st0[2] = inv_mix_columns(inv_subshift(st1, 2)) ^ rkp[6];
366 st0[3] = inv_mix_columns(inv_subshift(st1, 3)) ^ rkp[7];
367 }
368
369 put_unaligned_le32(inv_subshift(st1, 0) ^ rkp[4], out);
370 put_unaligned_le32(inv_subshift(st1, 1) ^ rkp[5], out + 4);
371 put_unaligned_le32(inv_subshift(st1, 2) ^ rkp[6], out + 8);
372 put_unaligned_le32(inv_subshift(st1, 3) ^ rkp[7], out + 12);
373 }
374 EXPORT_SYMBOL(aes_decrypt);
375
376 MODULE_DESCRIPTION("Generic AES library");
377 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
378 MODULE_LICENSE("GPL v2");
379