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crypto: atmel-aes - Add fallback to XTS software implementation

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XTS is supported just for input lengths with data units of 128-bit blocks.
Add a fallback to software implementation when the last block is shorter
than 128 bits.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Tudor Ambarus 2021-07-20 11:55:34 +03:00 committed by Herbert Xu
parent 76d579f251
commit bf2db8e742
1 changed files with 51 additions and 4 deletions
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55
drivers/crypto/atmel-aes.c
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@ -143,6 +143,7 @@ struct atmel_aes_xts_ctx {
struct atmel_aes_base_ctx base;
u32 key2[AES_KEYSIZE_256 / sizeof(u32)];
struct crypto_skcipher *fallback_tfm;
};
#if IS_ENABLED(CONFIG_CRYPTO_DEV_ATMEL_AUTHENC)
@ -155,6 +156,7 @@ struct atmel_aes_authenc_ctx {
struct atmel_aes_reqctx {
unsigned long mode;
u8 lastc[AES_BLOCK_SIZE];
struct skcipher_request fallback_req;
};
#if IS_ENABLED(CONFIG_CRYPTO_DEV_ATMEL_AUTHENC)
@ -1083,6 +1085,22 @@ static int atmel_aes_ctr_start(struct atmel_aes_dev *dd)
return atmel_aes_ctr_transfer(dd);
}
static int atmel_aes_xts_fallback(struct skcipher_request *req, bool enc)
{
struct atmel_aes_reqctx *rctx = skcipher_request_ctx(req);
struct atmel_aes_xts_ctx *ctx = crypto_skcipher_ctx(
crypto_skcipher_reqtfm(req));
skcipher_request_set_tfm(&rctx->fallback_req, ctx->fallback_tfm);
skcipher_request_set_callback(&rctx->fallback_req, req->base.flags,
req->base.complete, req->base.data);
skcipher_request_set_crypt(&rctx->fallback_req, req->src, req->dst,
req->cryptlen, req->iv);
return enc ? crypto_skcipher_encrypt(&rctx->fallback_req) :
crypto_skcipher_decrypt(&rctx->fallback_req);
}
static int atmel_aes_crypt(struct skcipher_request *req, unsigned long mode)
{
struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
@ -1091,8 +1109,14 @@ static int atmel_aes_crypt(struct skcipher_request *req, unsigned long mode)
struct atmel_aes_dev *dd;
u32 opmode = mode & AES_FLAGS_OPMODE_MASK;
if (opmode == AES_FLAGS_XTS && req->cryptlen < XTS_BLOCK_SIZE)
return -EINVAL;
if (opmode == AES_FLAGS_XTS) {
if (req->cryptlen < XTS_BLOCK_SIZE)
return -EINVAL;
if (!IS_ALIGNED(req->cryptlen, XTS_BLOCK_SIZE))
return atmel_aes_xts_fallback(req,
mode & AES_FLAGS_ENCRYPT);
}
/*
* ECB, CBC, CFB, OFB or CTR mode require the plaintext and ciphertext
@ -1864,6 +1888,13 @@ static int atmel_aes_xts_setkey(struct crypto_skcipher *tfm, const u8 *key,
if (err)
return err;
crypto_skcipher_clear_flags(ctx->fallback_tfm, CRYPTO_TFM_REQ_MASK);
crypto_skcipher_set_flags(ctx->fallback_tfm, tfm->base.crt_flags &
CRYPTO_TFM_REQ_MASK);
err = crypto_skcipher_setkey(ctx->fallback_tfm, key, keylen);
if (err)
return err;
memcpy(ctx->base.key, key, keylen/2);
memcpy(ctx->key2, key + keylen/2, keylen/2);
ctx->base.keylen = keylen/2;
@ -1884,18 +1915,33 @@ static int atmel_aes_xts_decrypt(struct skcipher_request *req)
static int atmel_aes_xts_init_tfm(struct crypto_skcipher *tfm)
{
struct atmel_aes_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
const char *tfm_name = crypto_tfm_alg_name(&tfm->base);
crypto_skcipher_set_reqsize(tfm, sizeof(struct atmel_aes_reqctx));
ctx->fallback_tfm = crypto_alloc_skcipher(tfm_name, 0,
CRYPTO_ALG_NEED_FALLBACK);
if (IS_ERR(ctx->fallback_tfm))
return PTR_ERR(ctx->fallback_tfm);
crypto_skcipher_set_reqsize(tfm, sizeof(struct atmel_aes_reqctx) +
crypto_skcipher_reqsize(ctx->fallback_tfm));
ctx->base.start = atmel_aes_xts_start;
return 0;
}
static void atmel_aes_xts_exit_tfm(struct crypto_skcipher *tfm)
{
struct atmel_aes_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
crypto_free_skcipher(ctx->fallback_tfm);
}
static struct skcipher_alg aes_xts_alg = {
.base.cra_name = "xts(aes)",
.base.cra_driver_name = "atmel-xts-aes",
.base.cra_blocksize = AES_BLOCK_SIZE,
.base.cra_ctxsize = sizeof(struct atmel_aes_xts_ctx),
.base.cra_flags = CRYPTO_ALG_NEED_FALLBACK,
.min_keysize = 2 * AES_MIN_KEY_SIZE,
.max_keysize = 2 * AES_MAX_KEY_SIZE,
@ -1904,6 +1950,7 @@ static struct skcipher_alg aes_xts_alg = {
.encrypt = atmel_aes_xts_encrypt,
.decrypt = atmel_aes_xts_decrypt,
.init = atmel_aes_xts_init_tfm,
.exit = atmel_aes_xts_exit_tfm,
};
#if IS_ENABLED(CONFIG_CRYPTO_DEV_ATMEL_AUTHENC)
@ -2373,7 +2420,7 @@ static void atmel_aes_unregister_algs(struct atmel_aes_dev *dd)
static void atmel_aes_crypto_alg_init(struct crypto_alg *alg)
{
alg->cra_flags = CRYPTO_ALG_ASYNC;
alg->cra_flags |= CRYPTO_ALG_ASYNC;
alg->cra_alignmask = 0xf;
alg->cra_priority = ATMEL_AES_PRIORITY;
alg->cra_module = THIS_MODULE;