crypto: atmel-tdes - Set the IV after {en,de}crypt

The req->iv of the skcipher_request is expected to contain the
last ciphertext block when the {en,de}crypt operation is done.
In case of in-place decryption, copy the ciphertext in an
intermediate buffer before decryption.

This fixes the following tcrypt tests:
alg: skcipher: atmel-cbc-des encryption test failed (wrong output IV) on test vector 0, cfg="in-place"
00000000: fe dc ba 98 76 54 32 10
alg: skcipher: atmel-cbc-tdes encryption test failed (wrong output IV) on test vector 0, cfg="in-place"
00000000: 7d 33 88 93 0f 93 b2 42
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/atmel-tdes.c

@@ -81,6 +81,7 @@ struct atmel_tdes_ctx {
 
 struct atmel_tdes_reqctx {
 	unsigned long mode;
+	u8 lastc[DES_BLOCK_SIZE];
 };
 
 struct atmel_tdes_dma {
@@ -572,6 +573,30 @@ static int atmel_tdes_crypt_start(struct atmel_tdes_dev *dd)
 	return err;
 }
 
+static void
+atmel_tdes_set_iv_as_last_ciphertext_block(struct atmel_tdes_dev *dd)
+{
+	struct skcipher_request *req = dd->req;
+	struct atmel_tdes_reqctx *rctx = skcipher_request_ctx(req);
+	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
+	unsigned int ivsize = crypto_skcipher_ivsize(skcipher);
+
+	if (req->cryptlen < ivsize)
+		return;
+
+	if (rctx->mode & TDES_FLAGS_ENCRYPT) {
+		scatterwalk_map_and_copy(req->iv, req->dst,
+					 req->cryptlen - ivsize, ivsize, 0);
+	} else {
+		if (req->src == req->dst)
+			memcpy(req->iv, rctx->lastc, ivsize);
+		else
+			scatterwalk_map_and_copy(req->iv, req->src,
+						 req->cryptlen - ivsize,
+						 ivsize, 0);
+	}
+}
+
 static void atmel_tdes_finish_req(struct atmel_tdes_dev *dd, int err)
 {
 	struct skcipher_request *req = dd->req;
@@ -580,6 +605,8 @@ static void atmel_tdes_finish_req(struct atmel_tdes_dev *dd, int err)
 
 	dd->flags &= ~TDES_FLAGS_BUSY;
 
+	atmel_tdes_set_iv_as_last_ciphertext_block(dd);
+
 	req->base.complete(&req->base, err);
 }
 
@@ -668,8 +695,8 @@ static int atmel_tdes_crypt_dma_stop(struct atmel_tdes_dev *dd)
 
 static int atmel_tdes_crypt(struct skcipher_request *req, unsigned long mode)
 {
-	struct atmel_tdes_ctx *ctx = crypto_skcipher_ctx(
-			crypto_skcipher_reqtfm(req));
+	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
+	struct atmel_tdes_ctx *ctx = crypto_skcipher_ctx(skcipher);
 	struct atmel_tdes_reqctx *rctx = skcipher_request_ctx(req);
 
 	if (mode & TDES_FLAGS_CFB8) {
@@ -700,6 +727,15 @@ static int atmel_tdes_crypt(struct skcipher_request *req, unsigned long mode)
 
 	rctx->mode = mode;
 
+	if (!(mode & TDES_FLAGS_ENCRYPT) && req->src == req->dst) {
+		unsigned int ivsize = crypto_skcipher_ivsize(skcipher);
+
+		if (req->cryptlen >= ivsize)
+			scatterwalk_map_and_copy(rctx->lastc, req->src,
+						 req->cryptlen - ivsize,
+						 ivsize, 0);
+	}
+
 	return atmel_tdes_handle_queue(ctx->dd, req);
 }