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Subject[PATCH] crypto: atmel-aes - properly set IV after {en,de}crypt
Date
Certain cipher modes like CTS expect the IV (req->info) of
ablkcipher_request (or equivalently req->iv of skcipher_request) to
contain the last ciphertext block when the {en,de}crypt operation is done.

Fix this issue for the Atmel AES hardware engine. The tcrypt test
case for cts(cbc(aes)) is now correctly passed.

To handle the case of in-place decryption, copy the ciphertext in an
intermediate buffer before decryption.

Signed-off-by: Romain Izard <romain.izard.pro@gmail.com>
---
drivers/crypto/atmel-aes.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)

diff --git a/drivers/crypto/atmel-aes.c b/drivers/crypto/atmel-aes.c
index 29e20c37f3a6..f22300babb45 100644
--- a/drivers/crypto/atmel-aes.c
+++ b/drivers/crypto/atmel-aes.c
@@ -156,6 +156,7 @@ struct atmel_aes_authenc_ctx {

struct atmel_aes_reqctx {
unsigned long mode;
+ u8 *backup_info;
};

#ifdef CONFIG_CRYPTO_DEV_ATMEL_AUTHENC
@@ -496,6 +497,12 @@ static void atmel_aes_authenc_complete(struct atmel_aes_dev *dd, int err);

static inline int atmel_aes_complete(struct atmel_aes_dev *dd, int err)
{
+ struct ablkcipher_request *req = ablkcipher_request_cast(dd->areq);
+ struct crypto_ablkcipher *ablkcipher = crypto_ablkcipher_reqtfm(req);
+ struct atmel_aes_reqctx *rctx = ablkcipher_request_ctx(req);
+ int ivsize = crypto_ablkcipher_ivsize(ablkcipher);
+ bool enc = atmel_aes_is_encrypt(dd);
+
#ifdef CONFIG_CRYPTO_DEV_ATMEL_AUTHENC
atmel_aes_authenc_complete(dd, err);
#endif
@@ -503,6 +510,15 @@ static inline int atmel_aes_complete(struct atmel_aes_dev *dd, int err)
clk_disable(dd->iclk);
dd->flags &= ~AES_FLAGS_BUSY;

+ if (enc) {
+ scatterwalk_map_and_copy(req->info, req->dst,
+ req->nbytes - ivsize, ivsize, 0);
+ } else if (rctx->backup_info) {
+ memcpy(req->info, rctx->backup_info, ivsize);
+ kfree(rctx->backup_info);
+ rctx->backup_info = NULL;
+ }
+
if (dd->is_async)
dd->areq->complete(dd->areq, err);

@@ -959,13 +975,25 @@ static int atmel_aes_transfer_complete(struct atmel_aes_dev *dd)
static int atmel_aes_start(struct atmel_aes_dev *dd)
{
struct ablkcipher_request *req = ablkcipher_request_cast(dd->areq);
+ struct crypto_ablkcipher *ablkcipher = crypto_ablkcipher_reqtfm(req);
struct atmel_aes_reqctx *rctx = ablkcipher_request_ctx(req);
+ int ivsize = crypto_ablkcipher_ivsize(ablkcipher);
+ bool enc = atmel_aes_is_encrypt(dd);
bool use_dma = (req->nbytes >= ATMEL_AES_DMA_THRESHOLD ||
dd->ctx->block_size != AES_BLOCK_SIZE);
int err;

atmel_aes_set_mode(dd, rctx);

+ if (!enc) {
+ rctx->backup_info = kzalloc(ivsize, GFP_KERNEL);
+ if (rctx->backup_info == NULL)
+ return atmel_aes_complete(dd, -ENOMEM);
+
+ scatterwalk_map_and_copy(rctx->backup_info, req->src,
+ (req->nbytes - ivsize), ivsize, 0);
+ }
+
err = atmel_aes_hw_init(dd);
if (err)
return atmel_aes_complete(dd, err);
--
2.11.0
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