Commit ed265f7f authored by Eric Biggers's avatar Eric Biggers Committed by Herbert Xu
Browse files

crypto: x86/aes-gcm - simplify GCM hash subkey derivation 



Remove a redundant expansion of the AES key, and use rodata for zeroes.
Also rename rfc4106_set_hash_subkey() to aes_gcm_derive_hash_subkey()
because it's used for both versions of AES-GCM, not just RFC4106.

Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent a0bbb1c1

arch/x86/crypto/aesni-intel_glue.c

+8 −18
Original line number Diff line number Diff line
@@ -40,7 +40,6 @@ 
#define AESNI_ALIGN	16

#define AESNI_ALIGN_ATTR __attribute__ ((__aligned__(AESNI_ALIGN)))

#define AES_BLOCK_MASK	(~(AES_BLOCK_SIZE - 1))

#define RFC4106_HASH_SUBKEY_SIZE 16

#define AESNI_ALIGN_EXTRA ((AESNI_ALIGN - 1) & ~(CRYPTO_MINALIGN - 1))

#define CRYPTO_AES_CTX_SIZE (sizeof(struct crypto_aes_ctx) + AESNI_ALIGN_EXTRA)

#define XTS_AES_CTX_SIZE (sizeof(struct aesni_xts_ctx) + AESNI_ALIGN_EXTRA)
@@ -590,23 +589,12 @@ static int xctr_crypt(struct skcipher_request *req) 
	return err;

}



static int

rfc4106_set_hash_subkey(u8 *hash_subkey, const u8 *key, unsigned int key_len)

static int aes_gcm_derive_hash_subkey(const struct crypto_aes_ctx *aes_key,

				      u8 hash_subkey[AES_BLOCK_SIZE])

{

	struct crypto_aes_ctx ctx;

	int ret;

	static const u8 zeroes[AES_BLOCK_SIZE];



	ret = aes_expandkey(&ctx, key, key_len);

	if (ret)

		return ret;



	/* Clear the data in the hash sub key container to zero.*/

	/* We want to cipher all zeros to create the hash sub key. */

	memset(hash_subkey, 0, RFC4106_HASH_SUBKEY_SIZE);



	aes_encrypt(&ctx, hash_subkey, hash_subkey);



	memzero_explicit(&ctx, sizeof(ctx));

	aes_encrypt(aes_key, hash_subkey, zeroes);

	return 0;

}
@@ -624,7 +612,8 @@ static int common_rfc4106_set_key(struct crypto_aead *aead, const u8 *key, 
	memcpy(ctx->nonce, key + key_len, sizeof(ctx->nonce));



	return aes_set_key_common(&ctx->aes_key_expanded, key, key_len) ?:

	       rfc4106_set_hash_subkey(ctx->hash_subkey, key, key_len);

	       aes_gcm_derive_hash_subkey(&ctx->aes_key_expanded,

					  ctx->hash_subkey);

}



/* This is the Integrity Check Value (aka the authentication tag) length and can
@@ -1327,7 +1316,8 @@ static int generic_gcmaes_set_key(struct crypto_aead *aead, const u8 *key, 
	struct generic_gcmaes_ctx *ctx = generic_gcmaes_ctx_get(aead);



	return aes_set_key_common(&ctx->aes_key_expanded, key, key_len) ?:

	       rfc4106_set_hash_subkey(ctx->hash_subkey, key, key_len);

	       aes_gcm_derive_hash_subkey(&ctx->aes_key_expanded,

					  ctx->hash_subkey);

}



static int generic_gcmaes_encrypt(struct aead_request *req)