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crypto: mediatek - use AES library for GCM key derivation 

The Mediatek accelerator driver calls into a dynamically allocated
skcipher of the ctr(aes) variety to perform GCM key derivation, which
involves AES encryption of a single block consisting of NUL bytes.

There is no point in using the skcipher API for this, so use the AES
library interface instead.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Ard Biesheuvel 2020-07-07 09:32:03 +03:00 committed by Herbert Xu
parent 56ca499f1b
commit f441ba2ad3
2 changed files with 9 additions and 57 deletions
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3
drivers/crypto/Kconfig
View File

@ -758,10 +758,9 @@ config CRYPTO_DEV_ZYNQMP_AES
config CRYPTO_DEV_MEDIATEK
tristate "MediaTek's EIP97 Cryptographic Engine driver"
depends on (ARM && ARCH_MEDIATEK) || COMPILE_TEST
select CRYPTO_AES
select CRYPTO_LIB_AES
select CRYPTO_AEAD
select CRYPTO_SKCIPHER
select CRYPTO_CTR
select CRYPTO_SHA1
select CRYPTO_SHA256
select CRYPTO_SHA512

63
drivers/crypto/mediatek/mtk-aes.c
View File

@ -137,8 +137,6 @@ struct mtk_aes_gcm_ctx {
u32 authsize;
size_t textlen;
struct crypto_skcipher *ctr;
};
struct mtk_aes_drv {
@ -996,17 +994,8 @@ static int mtk_aes_gcm_setkey(struct crypto_aead *aead, const u8 *key,
u32 keylen)
{
struct mtk_aes_base_ctx *ctx = crypto_aead_ctx(aead);
struct mtk_aes_gcm_ctx *gctx = mtk_aes_gcm_ctx_cast(ctx);
struct crypto_skcipher *ctr = gctx->ctr;
struct {
u32 hash[4];
u8 iv[8];
struct crypto_wait wait;
struct scatterlist sg[1];
struct skcipher_request req;
} *data;
u8 hash[AES_BLOCK_SIZE] __aligned(4) = {};
struct crypto_aes_ctx aes_ctx;
int err;
switch (keylen) {
@ -1026,39 +1015,18 @@ static int mtk_aes_gcm_setkey(struct crypto_aead *aead, const u8 *key,
ctx->keylen = SIZE_IN_WORDS(keylen);
/* Same as crypto_gcm_setkey() from crypto/gcm.c */
crypto_skcipher_clear_flags(ctr, CRYPTO_TFM_REQ_MASK);
crypto_skcipher_set_flags(ctr, crypto_aead_get_flags(aead) &
CRYPTO_TFM_REQ_MASK);
err = crypto_skcipher_setkey(ctr, key, keylen);
err = aes_expandkey(&aes_ctx, key, keylen);
if (err)
return err;
data = kzalloc(sizeof(*data) + crypto_skcipher_reqsize(ctr),
GFP_KERNEL);
if (!data)
return -ENOMEM;
crypto_init_wait(&data->wait);
sg_init_one(data->sg, &data->hash, AES_BLOCK_SIZE);
skcipher_request_set_tfm(&data->req, ctr);
skcipher_request_set_callback(&data->req, CRYPTO_TFM_REQ_MAY_SLEEP |
CRYPTO_TFM_REQ_MAY_BACKLOG,
crypto_req_done, &data->wait);
skcipher_request_set_crypt(&data->req, data->sg, data->sg,
AES_BLOCK_SIZE, data->iv);
err = crypto_wait_req(crypto_skcipher_encrypt(&data->req),
&data->wait);
if (err)
goto out;
aes_encrypt(&aes_ctx, hash, hash);
memzero_explicit(&aes_ctx, sizeof(aes_ctx));
mtk_aes_write_state_le(ctx->key, (const u32 *)key, keylen);
mtk_aes_write_state_be(ctx->key + ctx->keylen, data->hash,
mtk_aes_write_state_be(ctx->key + ctx->keylen, (const u32 *)hash,
AES_BLOCK_SIZE);
out:
kzfree(data);
return err;
return 0;
}
static int mtk_aes_gcm_setauthsize(struct crypto_aead *aead,
@ -1095,32 +1063,17 @@ static int mtk_aes_gcm_init(struct crypto_aead *aead)
{
struct mtk_aes_gcm_ctx *ctx = crypto_aead_ctx(aead);
ctx->ctr = crypto_alloc_skcipher("ctr(aes)", 0,
CRYPTO_ALG_ASYNC);
if (IS_ERR(ctx->ctr)) {
pr_err("Error allocating ctr(aes)\n");
return PTR_ERR(ctx->ctr);
}
crypto_aead_set_reqsize(aead, sizeof(struct mtk_aes_reqctx));
ctx->base.start = mtk_aes_gcm_start;
return 0;
}
static void mtk_aes_gcm_exit(struct crypto_aead *aead)
{
struct mtk_aes_gcm_ctx *ctx = crypto_aead_ctx(aead);
crypto_free_skcipher(ctx->ctr);
}
static struct aead_alg aes_gcm_alg = {
.setkey = mtk_aes_gcm_setkey,
.setauthsize = mtk_aes_gcm_setauthsize,
.encrypt = mtk_aes_gcm_encrypt,
.decrypt = mtk_aes_gcm_decrypt,
.init = mtk_aes_gcm_init,
.exit = mtk_aes_gcm_exit,
.ivsize = GCM_AES_IV_SIZE,
.maxauthsize = AES_BLOCK_SIZE,