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Diffstat (limited to 'lib/crypto/aes.c')
| -rw-r--r-- | lib/crypto/aes.c | 356 |
1 files changed, 356 insertions, 0 deletions
diff --git a/lib/crypto/aes.c b/lib/crypto/aes.c new file mode 100644 index 000000000..827fe8992 --- /dev/null +++ b/lib/crypto/aes.c @@ -0,0 +1,356 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2017-2019 Linaro Ltd <ard.biesheuvel@linaro.org> + */ + +#include <crypto/aes.h> +#include <linux/crypto.h> +#include <linux/module.h> +#include <asm/unaligned.h> + +/* + * Emit the sbox as volatile const to prevent the compiler from doing + * constant folding on sbox references involving fixed indexes. + */ +static volatile const u8 __cacheline_aligned aes_sbox[] = { + 0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, + 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76, + 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, + 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0, + 0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, + 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15, + 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, + 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75, + 0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, + 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84, + 0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, + 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf, + 0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, + 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8, + 0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, + 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2, + 0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, + 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73, + 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, + 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb, + 0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, + 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79, + 0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, + 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08, + 0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, + 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a, + 0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, + 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e, + 0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, + 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf, + 0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, + 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16, +}; + +static volatile const u8 __cacheline_aligned aes_inv_sbox[] = { + 0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, + 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb, + 0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, + 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb, + 0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, + 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e, + 0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, + 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25, + 0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, + 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92, + 0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, + 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84, + 0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, + 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06, + 0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, + 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b, + 0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, + 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73, + 0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, + 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e, + 0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, + 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b, + 0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, + 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4, + 0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, + 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f, + 0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, + 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef, + 0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, + 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61, + 0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, + 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d, +}; + +extern const u8 crypto_aes_sbox[256] __alias(aes_sbox); +extern const u8 crypto_aes_inv_sbox[256] __alias(aes_inv_sbox); + +EXPORT_SYMBOL(crypto_aes_sbox); +EXPORT_SYMBOL(crypto_aes_inv_sbox); + +static u32 mul_by_x(u32 w) +{ + u32 x = w & 0x7f7f7f7f; + u32 y = w & 0x80808080; + + /* multiply by polynomial 'x' (0b10) in GF(2^8) */ + return (x << 1) ^ (y >> 7) * 0x1b; +} + +static u32 mul_by_x2(u32 w) +{ + u32 x = w & 0x3f3f3f3f; + u32 y = w & 0x80808080; + u32 z = w & 0x40404040; + + /* multiply by polynomial 'x^2' (0b100) in GF(2^8) */ + return (x << 2) ^ (y >> 7) * 0x36 ^ (z >> 6) * 0x1b; +} + +static u32 mix_columns(u32 x) +{ + /* + * Perform the following matrix multiplication in GF(2^8) + * + * | 0x2 0x3 0x1 0x1 | | x[0] | + * | 0x1 0x2 0x3 0x1 | | x[1] | + * | 0x1 0x1 0x2 0x3 | x | x[2] | + * | 0x3 0x1 0x1 0x2 | | x[3] | + */ + u32 y = mul_by_x(x) ^ ror32(x, 16); + + return y ^ ror32(x ^ y, 8); +} + +static u32 inv_mix_columns(u32 x) +{ + /* + * Perform the following matrix multiplication in GF(2^8) + * + * | 0xe 0xb 0xd 0x9 | | x[0] | + * | 0x9 0xe 0xb 0xd | | x[1] | + * | 0xd 0x9 0xe 0xb | x | x[2] | + * | 0xb 0xd 0x9 0xe | | x[3] | + * + * which can conveniently be reduced to + * + * | 0x2 0x3 0x1 0x1 | | 0x5 0x0 0x4 0x0 | | x[0] | + * | 0x1 0x2 0x3 0x1 | | 0x0 0x5 0x0 0x4 | | x[1] | + * | 0x1 0x1 0x2 0x3 | x | 0x4 0x0 0x5 0x0 | x | x[2] | + * | 0x3 0x1 0x1 0x2 | | 0x0 0x4 0x0 0x5 | | x[3] | + */ + u32 y = mul_by_x2(x); + + return mix_columns(x ^ y ^ ror32(y, 16)); +} + +static __always_inline u32 subshift(u32 in[], int pos) +{ + return (aes_sbox[in[pos] & 0xff]) ^ + (aes_sbox[(in[(pos + 1) % 4] >> 8) & 0xff] << 8) ^ + (aes_sbox[(in[(pos + 2) % 4] >> 16) & 0xff] << 16) ^ + (aes_sbox[(in[(pos + 3) % 4] >> 24) & 0xff] << 24); +} + +static __always_inline u32 inv_subshift(u32 in[], int pos) +{ + return (aes_inv_sbox[in[pos] & 0xff]) ^ + (aes_inv_sbox[(in[(pos + 3) % 4] >> 8) & 0xff] << 8) ^ + (aes_inv_sbox[(in[(pos + 2) % 4] >> 16) & 0xff] << 16) ^ + (aes_inv_sbox[(in[(pos + 1) % 4] >> 24) & 0xff] << 24); +} + +static u32 subw(u32 in) +{ + return (aes_sbox[in & 0xff]) ^ + (aes_sbox[(in >> 8) & 0xff] << 8) ^ + (aes_sbox[(in >> 16) & 0xff] << 16) ^ + (aes_sbox[(in >> 24) & 0xff] << 24); +} + +/** + * aes_expandkey - Expands the AES key as described in FIPS-197 + * @ctx: The location where the computed key will be stored. + * @in_key: The supplied key. + * @key_len: The length of the supplied key. + * + * Returns 0 on success. The function fails only if an invalid key size (or + * pointer) is supplied. + * The expanded key size is 240 bytes (max of 14 rounds with a unique 16 bytes + * key schedule plus a 16 bytes key which is used before the first round). + * The decryption key is prepared for the "Equivalent Inverse Cipher" as + * described in FIPS-197. The first slot (16 bytes) of each key (enc or dec) is + * for the initial combination, the second slot for the first round and so on. + */ +int aes_expandkey(struct crypto_aes_ctx *ctx, const u8 *in_key, + unsigned int key_len) +{ + u32 kwords = key_len / sizeof(u32); + u32 rc, i, j; + int err; + + err = aes_check_keylen(key_len); + if (err) + return err; + + ctx->key_length = key_len; + + for (i = 0; i < kwords; i++) + ctx->key_enc[i] = get_unaligned_le32(in_key + i * sizeof(u32)); + + for (i = 0, rc = 1; i < 10; i++, rc = mul_by_x(rc)) { + u32 *rki = ctx->key_enc + (i * kwords); + u32 *rko = rki + kwords; + + rko[0] = ror32(subw(rki[kwords - 1]), 8) ^ rc ^ rki[0]; + rko[1] = rko[0] ^ rki[1]; + rko[2] = rko[1] ^ rki[2]; + rko[3] = rko[2] ^ rki[3]; + + if (key_len == AES_KEYSIZE_192) { + if (i >= 7) + break; + rko[4] = rko[3] ^ rki[4]; + rko[5] = rko[4] ^ rki[5]; + } else if (key_len == AES_KEYSIZE_256) { + if (i >= 6) + break; + rko[4] = subw(rko[3]) ^ rki[4]; + rko[5] = rko[4] ^ rki[5]; + rko[6] = rko[5] ^ rki[6]; + rko[7] = rko[6] ^ rki[7]; + } + } + + /* + * Generate the decryption keys for the Equivalent Inverse Cipher. + * This involves reversing the order of the round keys, and applying + * the Inverse Mix Columns transformation to all but the first and + * the last one. + */ + ctx->key_dec[0] = ctx->key_enc[key_len + 24]; + ctx->key_dec[1] = ctx->key_enc[key_len + 25]; + ctx->key_dec[2] = ctx->key_enc[key_len + 26]; + ctx->key_dec[3] = ctx->key_enc[key_len + 27]; + + for (i = 4, j = key_len + 20; j > 0; i += 4, j -= 4) { + ctx->key_dec[i] = inv_mix_columns(ctx->key_enc[j]); + ctx->key_dec[i + 1] = inv_mix_columns(ctx->key_enc[j + 1]); + ctx->key_dec[i + 2] = inv_mix_columns(ctx->key_enc[j + 2]); + ctx->key_dec[i + 3] = inv_mix_columns(ctx->key_enc[j + 3]); + } + + ctx->key_dec[i] = ctx->key_enc[0]; + ctx->key_dec[i + 1] = ctx->key_enc[1]; + ctx->key_dec[i + 2] = ctx->key_enc[2]; + ctx->key_dec[i + 3] = ctx->key_enc[3]; + + return 0; +} +EXPORT_SYMBOL(aes_expandkey); + +/** + * aes_encrypt - Encrypt a single AES block + * @ctx: Context struct containing the key schedule + * @out: Buffer to store the ciphertext + * @in: Buffer containing the plaintext + */ +void aes_encrypt(const struct crypto_aes_ctx *ctx, u8 *out, const u8 *in) +{ + const u32 *rkp = ctx->key_enc + 4; + int rounds = 6 + ctx->key_length / 4; + u32 st0[4], st1[4]; + int round; + + st0[0] = ctx->key_enc[0] ^ get_unaligned_le32(in); + st0[1] = ctx->key_enc[1] ^ get_unaligned_le32(in + 4); + st0[2] = ctx->key_enc[2] ^ get_unaligned_le32(in + 8); + st0[3] = ctx->key_enc[3] ^ get_unaligned_le32(in + 12); + + /* + * Force the compiler to emit data independent Sbox references, + * by xoring the input with Sbox values that are known to add up + * to zero. This pulls the entire Sbox into the D-cache before any + * data dependent lookups are done. + */ + st0[0] ^= aes_sbox[ 0] ^ aes_sbox[ 64] ^ aes_sbox[134] ^ aes_sbox[195]; + st0[1] ^= aes_sbox[16] ^ aes_sbox[ 82] ^ aes_sbox[158] ^ aes_sbox[221]; + st0[2] ^= aes_sbox[32] ^ aes_sbox[ 96] ^ aes_sbox[160] ^ aes_sbox[234]; + st0[3] ^= aes_sbox[48] ^ aes_sbox[112] ^ aes_sbox[186] ^ aes_sbox[241]; + + for (round = 0;; round += 2, rkp += 8) { + st1[0] = mix_columns(subshift(st0, 0)) ^ rkp[0]; + st1[1] = mix_columns(subshift(st0, 1)) ^ rkp[1]; + st1[2] = mix_columns(subshift(st0, 2)) ^ rkp[2]; + st1[3] = mix_columns(subshift(st0, 3)) ^ rkp[3]; + + if (round == rounds - 2) + break; + + st0[0] = mix_columns(subshift(st1, 0)) ^ rkp[4]; + st0[1] = mix_columns(subshift(st1, 1)) ^ rkp[5]; + st0[2] = mix_columns(subshift(st1, 2)) ^ rkp[6]; + st0[3] = mix_columns(subshift(st1, 3)) ^ rkp[7]; + } + + put_unaligned_le32(subshift(st1, 0) ^ rkp[4], out); + put_unaligned_le32(subshift(st1, 1) ^ rkp[5], out + 4); + put_unaligned_le32(subshift(st1, 2) ^ rkp[6], out + 8); + put_unaligned_le32(subshift(st1, 3) ^ rkp[7], out + 12); +} +EXPORT_SYMBOL(aes_encrypt); + +/** + * aes_decrypt - Decrypt a single AES block + * @ctx: Context struct containing the key schedule + * @out: Buffer to store the plaintext + * @in: Buffer containing the ciphertext + */ +void aes_decrypt(const struct crypto_aes_ctx *ctx, u8 *out, const u8 *in) +{ + const u32 *rkp = ctx->key_dec + 4; + int rounds = 6 + ctx->key_length / 4; + u32 st0[4], st1[4]; + int round; + + st0[0] = ctx->key_dec[0] ^ get_unaligned_le32(in); + st0[1] = ctx->key_dec[1] ^ get_unaligned_le32(in + 4); + st0[2] = ctx->key_dec[2] ^ get_unaligned_le32(in + 8); + st0[3] = ctx->key_dec[3] ^ get_unaligned_le32(in + 12); + + /* + * Force the compiler to emit data independent Sbox references, + * by xoring the input with Sbox values that are known to add up + * to zero. This pulls the entire Sbox into the D-cache before any + * data dependent lookups are done. + */ + st0[0] ^= aes_inv_sbox[ 0] ^ aes_inv_sbox[ 64] ^ aes_inv_sbox[129] ^ aes_inv_sbox[200]; + st0[1] ^= aes_inv_sbox[16] ^ aes_inv_sbox[ 83] ^ aes_inv_sbox[150] ^ aes_inv_sbox[212]; + st0[2] ^= aes_inv_sbox[32] ^ aes_inv_sbox[ 96] ^ aes_inv_sbox[160] ^ aes_inv_sbox[236]; + st0[3] ^= aes_inv_sbox[48] ^ aes_inv_sbox[112] ^ aes_inv_sbox[187] ^ aes_inv_sbox[247]; + + for (round = 0;; round += 2, rkp += 8) { + st1[0] = inv_mix_columns(inv_subshift(st0, 0)) ^ rkp[0]; + st1[1] = inv_mix_columns(inv_subshift(st0, 1)) ^ rkp[1]; + st1[2] = inv_mix_columns(inv_subshift(st0, 2)) ^ rkp[2]; + st1[3] = inv_mix_columns(inv_subshift(st0, 3)) ^ rkp[3]; + + if (round == rounds - 2) + break; + + st0[0] = inv_mix_columns(inv_subshift(st1, 0)) ^ rkp[4]; + st0[1] = inv_mix_columns(inv_subshift(st1, 1)) ^ rkp[5]; + st0[2] = inv_mix_columns(inv_subshift(st1, 2)) ^ rkp[6]; + st0[3] = inv_mix_columns(inv_subshift(st1, 3)) ^ rkp[7]; + } + + put_unaligned_le32(inv_subshift(st1, 0) ^ rkp[4], out); + put_unaligned_le32(inv_subshift(st1, 1) ^ rkp[5], out + 4); + put_unaligned_le32(inv_subshift(st1, 2) ^ rkp[6], out + 8); + put_unaligned_le32(inv_subshift(st1, 3) ^ rkp[7], out + 12); +} +EXPORT_SYMBOL(aes_decrypt); + +MODULE_DESCRIPTION("Generic AES library"); +MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>"); +MODULE_LICENSE("GPL v2"); |