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crypto: aes-generic - drop alignment requirement
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The generic AES code exposes a 32-bit align mask, which forces all
users of the code to use temporary buffers or take other measures to
ensure the alignment requirement is adhered to, even on architectures
that don't care about alignment for software algorithms such as this
one.

So drop the align mask, and fix the code to use get_unaligned_le32()
where appropriate, which will resolve to whatever is optimal for the
architecture.

Signed-off-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>
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@herbertx
Ard Biesheuvel authored and herbertx committed Feb 11, 2017
1 parent c459bd7 commit ec38a93
Showing 1 changed file with 32 additions and 32 deletions.
64 changes: 32 additions & 32 deletions crypto/aes_generic.c
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Original file line number Diff line number Diff line change
Expand Up @@ -54,6 +54,7 @@
#include <linux/errno.h>
#include <linux/crypto.h>
#include <asm/byteorder.h>
#include <asm/unaligned.h>

static inline u8 byte(const u32 x, const unsigned n)
{
Expand Down Expand Up @@ -1216,7 +1217,6 @@ EXPORT_SYMBOL_GPL(crypto_il_tab);
int crypto_aes_expand_key(struct crypto_aes_ctx *ctx, const u8 *in_key,
unsigned int key_len)
{
const __le32 *key = (const __le32 *)in_key;
u32 i, t, u, v, w, j;

if (key_len != AES_KEYSIZE_128 && key_len != AES_KEYSIZE_192 &&
Expand All @@ -1225,10 +1225,15 @@ int crypto_aes_expand_key(struct crypto_aes_ctx *ctx, const u8 *in_key,

ctx->key_length = key_len;

ctx->key_dec[key_len + 24] = ctx->key_enc[0] = le32_to_cpu(key[0]);
ctx->key_dec[key_len + 25] = ctx->key_enc[1] = le32_to_cpu(key[1]);
ctx->key_dec[key_len + 26] = ctx->key_enc[2] = le32_to_cpu(key[2]);
ctx->key_dec[key_len + 27] = ctx->key_enc[3] = le32_to_cpu(key[3]);
ctx->key_enc[0] = get_unaligned_le32(in_key);
ctx->key_enc[1] = get_unaligned_le32(in_key + 4);
ctx->key_enc[2] = get_unaligned_le32(in_key + 8);
ctx->key_enc[3] = get_unaligned_le32(in_key + 12);

ctx->key_dec[key_len + 24] = ctx->key_enc[0];
ctx->key_dec[key_len + 25] = ctx->key_enc[1];
ctx->key_dec[key_len + 26] = ctx->key_enc[2];
ctx->key_dec[key_len + 27] = ctx->key_enc[3];

switch (key_len) {
case AES_KEYSIZE_128:
Expand All @@ -1238,17 +1243,17 @@ int crypto_aes_expand_key(struct crypto_aes_ctx *ctx, const u8 *in_key,
break;

case AES_KEYSIZE_192:
ctx->key_enc[4] = le32_to_cpu(key[4]);
t = ctx->key_enc[5] = le32_to_cpu(key[5]);
ctx->key_enc[4] = get_unaligned_le32(in_key + 16);
t = ctx->key_enc[5] = get_unaligned_le32(in_key + 20);
for (i = 0; i < 8; ++i)
loop6(i);
break;

case AES_KEYSIZE_256:
ctx->key_enc[4] = le32_to_cpu(key[4]);
ctx->key_enc[5] = le32_to_cpu(key[5]);
ctx->key_enc[6] = le32_to_cpu(key[6]);
t = ctx->key_enc[7] = le32_to_cpu(key[7]);
ctx->key_enc[4] = get_unaligned_le32(in_key + 16);
ctx->key_enc[5] = get_unaligned_le32(in_key + 20);
ctx->key_enc[6] = get_unaligned_le32(in_key + 24);
t = ctx->key_enc[7] = get_unaligned_le32(in_key + 28);
for (i = 0; i < 6; ++i)
loop8(i);
loop8tophalf(i);
Expand Down Expand Up @@ -1329,16 +1334,14 @@ EXPORT_SYMBOL_GPL(crypto_aes_set_key);
static void aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
const __le32 *src = (const __le32 *)in;
__le32 *dst = (__le32 *)out;
u32 b0[4], b1[4];
const u32 *kp = ctx->key_enc + 4;
const int key_len = ctx->key_length;

b0[0] = le32_to_cpu(src[0]) ^ ctx->key_enc[0];
b0[1] = le32_to_cpu(src[1]) ^ ctx->key_enc[1];
b0[2] = le32_to_cpu(src[2]) ^ ctx->key_enc[2];
b0[3] = le32_to_cpu(src[3]) ^ ctx->key_enc[3];
b0[0] = ctx->key_enc[0] ^ get_unaligned_le32(in);
b0[1] = ctx->key_enc[1] ^ get_unaligned_le32(in + 4);
b0[2] = ctx->key_enc[2] ^ get_unaligned_le32(in + 8);
b0[3] = ctx->key_enc[3] ^ get_unaligned_le32(in + 12);

if (key_len > 24) {
f_nround(b1, b0, kp);
Expand All @@ -1361,10 +1364,10 @@ static void aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
f_nround(b1, b0, kp);
f_lround(b0, b1, kp);

dst[0] = cpu_to_le32(b0[0]);
dst[1] = cpu_to_le32(b0[1]);
dst[2] = cpu_to_le32(b0[2]);
dst[3] = cpu_to_le32(b0[3]);
put_unaligned_le32(b0[0], out);
put_unaligned_le32(b0[1], out + 4);
put_unaligned_le32(b0[2], out + 8);
put_unaligned_le32(b0[3], out + 12);
}

/* decrypt a block of text */
Expand Down Expand Up @@ -1401,16 +1404,14 @@ static void aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
static void aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
const __le32 *src = (const __le32 *)in;
__le32 *dst = (__le32 *)out;
u32 b0[4], b1[4];
const int key_len = ctx->key_length;
const u32 *kp = ctx->key_dec + 4;

b0[0] = le32_to_cpu(src[0]) ^ ctx->key_dec[0];
b0[1] = le32_to_cpu(src[1]) ^ ctx->key_dec[1];
b0[2] = le32_to_cpu(src[2]) ^ ctx->key_dec[2];
b0[3] = le32_to_cpu(src[3]) ^ ctx->key_dec[3];
b0[0] = ctx->key_dec[0] ^ get_unaligned_le32(in);
b0[1] = ctx->key_dec[1] ^ get_unaligned_le32(in + 4);
b0[2] = ctx->key_dec[2] ^ get_unaligned_le32(in + 8);
b0[3] = ctx->key_dec[3] ^ get_unaligned_le32(in + 12);

if (key_len > 24) {
i_nround(b1, b0, kp);
Expand All @@ -1433,10 +1434,10 @@ static void aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
i_nround(b1, b0, kp);
i_lround(b0, b1, kp);

dst[0] = cpu_to_le32(b0[0]);
dst[1] = cpu_to_le32(b0[1]);
dst[2] = cpu_to_le32(b0[2]);
dst[3] = cpu_to_le32(b0[3]);
put_unaligned_le32(b0[0], out);
put_unaligned_le32(b0[1], out + 4);
put_unaligned_le32(b0[2], out + 8);
put_unaligned_le32(b0[3], out + 12);
}

static struct crypto_alg aes_alg = {
Expand All @@ -1446,7 +1447,6 @@ static struct crypto_alg aes_alg = {
.cra_flags = CRYPTO_ALG_TYPE_CIPHER,
.cra_blocksize = AES_BLOCK_SIZE,
.cra_ctxsize = sizeof(struct crypto_aes_ctx),
.cra_alignmask = 3,
.cra_module = THIS_MODULE,
.cra_u = {
.cipher = {
Expand Down

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