357 lines · c
1// SPDX-License-Identifier: GPL-2.02/*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 <linux/unaligned.h>10 11/*12 * Emit the sbox as volatile const to prevent the compiler from doing13 * constant folding on sbox references involving fixed indexes.14 */15static 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 50static 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 85extern const u8 crypto_aes_sbox[256] __alias(aes_sbox);86extern const u8 crypto_aes_inv_sbox[256] __alias(aes_inv_sbox);87 88EXPORT_SYMBOL(crypto_aes_sbox);89EXPORT_SYMBOL(crypto_aes_inv_sbox);90 91static 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 100static 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 110static 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(x) ^ ror32(x, 16);121 122 return y ^ ror32(x ^ y, 8);123}124 125static 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 to136 *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(x);143 144 return mix_columns(x ^ y ^ ror32(y, 16));145}146 147static __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 155static __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 163static 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-197173 * @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 (or178 * pointer) is supplied.179 * The expanded key size is 240 bytes (max of 14 rounds with a unique 16 bytes180 * 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" as182 * described in FIPS-197. The first slot (16 bytes) of each key (enc or dec) is183 * for the initial combination, the second slot for the first round and so on.184 */185int 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(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(in_key + i * sizeof(u32));200 201 for (i = 0, rc = 1; i < 10; i++, rc = mul_by_x(rc)) {202 u32 *rki = ctx->key_enc + (i * kwords);203 u32 *rko = rki + kwords;204 205 rko[0] = ror32(subw(rki[kwords - 1]), 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(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 applying228 * the Inverse Mix Columns transformation to all but the first and229 * 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(ctx->key_enc[j]);238 ctx->key_dec[i + 1] = inv_mix_columns(ctx->key_enc[j + 1]);239 ctx->key_dec[i + 2] = inv_mix_columns(ctx->key_enc[j + 2]);240 ctx->key_dec[i + 3] = inv_mix_columns(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}250EXPORT_SYMBOL(aes_expandkey);251 252/**253 * aes_encrypt - Encrypt a single AES block254 * @ctx: Context struct containing the key schedule255 * @out: Buffer to store the ciphertext256 * @in: Buffer containing the plaintext257 */258void 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(in);266 st0[1] = ctx->key_enc[1] ^ get_unaligned_le32(in + 4);267 st0[2] = ctx->key_enc[2] ^ get_unaligned_le32(in + 8);268 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 up273 * to zero. This pulls the entire Sbox into the D-cache before any274 * 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(subshift(st0, 0)) ^ rkp[0];283 st1[1] = mix_columns(subshift(st0, 1)) ^ rkp[1];284 st1[2] = mix_columns(subshift(st0, 2)) ^ rkp[2];285 st1[3] = mix_columns(subshift(st0, 3)) ^ rkp[3];286 287 if (round == rounds - 2)288 break;289 290 st0[0] = mix_columns(subshift(st1, 0)) ^ rkp[4];291 st0[1] = mix_columns(subshift(st1, 1)) ^ rkp[5];292 st0[2] = mix_columns(subshift(st1, 2)) ^ rkp[6];293 st0[3] = mix_columns(subshift(st1, 3)) ^ rkp[7];294 }295 296 put_unaligned_le32(subshift(st1, 0) ^ rkp[4], out);297 put_unaligned_le32(subshift(st1, 1) ^ rkp[5], out + 4);298 put_unaligned_le32(subshift(st1, 2) ^ rkp[6], out + 8);299 put_unaligned_le32(subshift(st1, 3) ^ rkp[7], out + 12);300}301EXPORT_SYMBOL(aes_encrypt);302 303/**304 * aes_decrypt - Decrypt a single AES block305 * @ctx: Context struct containing the key schedule306 * @out: Buffer to store the plaintext307 * @in: Buffer containing the ciphertext308 */309void 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(in);317 st0[1] = ctx->key_dec[1] ^ get_unaligned_le32(in + 4);318 st0[2] = ctx->key_dec[2] ^ get_unaligned_le32(in + 8);319 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 up324 * to zero. This pulls the entire Sbox into the D-cache before any325 * 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(inv_subshift(st0, 0)) ^ rkp[0];334 st1[1] = inv_mix_columns(inv_subshift(st0, 1)) ^ rkp[1];335 st1[2] = inv_mix_columns(inv_subshift(st0, 2)) ^ rkp[2];336 st1[3] = inv_mix_columns(inv_subshift(st0, 3)) ^ rkp[3];337 338 if (round == rounds - 2)339 break;340 341 st0[0] = inv_mix_columns(inv_subshift(st1, 0)) ^ rkp[4];342 st0[1] = inv_mix_columns(inv_subshift(st1, 1)) ^ rkp[5];343 st0[2] = inv_mix_columns(inv_subshift(st1, 2)) ^ rkp[6];344 st0[3] = inv_mix_columns(inv_subshift(st1, 3)) ^ rkp[7];345 }346 347 put_unaligned_le32(inv_subshift(st1, 0) ^ rkp[4], out);348 put_unaligned_le32(inv_subshift(st1, 1) ^ rkp[5], out + 4);349 put_unaligned_le32(inv_subshift(st1, 2) ^ rkp[6], out + 8);350 put_unaligned_le32(inv_subshift(st1, 3) ^ rkp[7], out + 12);351}352EXPORT_SYMBOL(aes_decrypt);353 354MODULE_DESCRIPTION("Generic AES library");355MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");356MODULE_LICENSE("GPL v2");357