crypto: sun4i-ss - do not allocate backup IV on requests

Instead of allocate memory on each requests, it is easier to
pre-allocate buffer for backup IV.
This made error path easier.
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/allwinner/sun4i-ss/sun4i-ss-cipher.c

@@ -20,7 +20,6 @@ static int noinline_for_stack sun4i_ss_opti_poll(struct skcipher_request *areq)
 	unsigned int ivsize = crypto_skcipher_ivsize(tfm);
 	struct sun4i_cipher_req_ctx *ctx = skcipher_request_ctx(areq);
 	u32 mode = ctx->mode;
-	void *backup_iv = NULL;
 	/* when activating SS, the default FIFO space is SS_RX_DEFAULT(32) */
 	u32 rx_cnt = SS_RX_DEFAULT;
 	u32 tx_cnt = 0;
@@ -48,10 +47,8 @@ static int noinline_for_stack sun4i_ss_opti_poll(struct skcipher_request *areq)
 	}
 
 	if (areq->iv && ivsize > 0 && mode & SS_DECRYPTION) {
-		backup_iv = kzalloc(ivsize, GFP_KERNEL);
-		if (!backup_iv)
-			return -ENOMEM;
-		scatterwalk_map_and_copy(backup_iv, areq->src, areq->cryptlen - ivsize, ivsize, 0);
+		scatterwalk_map_and_copy(ctx->backup_iv, areq->src,
+					 areq->cryptlen - ivsize, ivsize, 0);
 	}
 
 	if (IS_ENABLED(CONFIG_CRYPTO_DEV_SUN4I_SS_DEBUG)) {
@@ -134,8 +131,8 @@ static int noinline_for_stack sun4i_ss_opti_poll(struct skcipher_request *areq)
 
 	if (areq->iv) {
 		if (mode & SS_DECRYPTION) {
-			memcpy(areq->iv, backup_iv, ivsize);
-			kfree_sensitive(backup_iv);
+			memcpy(areq->iv, ctx->backup_iv, ivsize);
+			memzero_explicit(ctx->backup_iv, ivsize);
 		} else {
 			scatterwalk_map_and_copy(areq->iv, areq->dst, areq->cryptlen - ivsize,
 						 ivsize, 0);
@@ -199,7 +196,6 @@ static int sun4i_ss_cipher_poll(struct skcipher_request *areq)
 	unsigned int ileft = areq->cryptlen;
 	unsigned int oleft = areq->cryptlen;
 	unsigned int todo;
-	void *backup_iv = NULL;
 	struct sg_mapping_iter mi, mo;
 	unsigned long pi = 0, po = 0; /* progress for in and out */
 	bool miter_err;
@@ -244,10 +240,8 @@ static int sun4i_ss_cipher_poll(struct skcipher_request *areq)
 		return sun4i_ss_cipher_poll_fallback(areq);
 
 	if (areq->iv && ivsize > 0 && mode & SS_DECRYPTION) {
-		backup_iv = kzalloc(ivsize, GFP_KERNEL);
-		if (!backup_iv)
-			return -ENOMEM;
-		scatterwalk_map_and_copy(backup_iv, areq->src, areq->cryptlen - ivsize, ivsize, 0);
+		scatterwalk_map_and_copy(ctx->backup_iv, areq->src,
+					 areq->cryptlen - ivsize, ivsize, 0);
 	}
 
 	if (IS_ENABLED(CONFIG_CRYPTO_DEV_SUN4I_SS_DEBUG)) {
@@ -384,8 +378,8 @@ static int sun4i_ss_cipher_poll(struct skcipher_request *areq)
 	}
 	if (areq->iv) {
 		if (mode & SS_DECRYPTION) {
-			memcpy(areq->iv, backup_iv, ivsize);
-			kfree_sensitive(backup_iv);
+			memcpy(areq->iv, ctx->backup_iv, ivsize);
+			memzero_explicit(ctx->backup_iv, ivsize);
 		} else {
 			scatterwalk_map_and_copy(areq->iv, areq->dst, areq->cryptlen - ivsize,
 						 ivsize, 0);

drivers/crypto/allwinner/sun4i-ss/sun4i-ss.h

@@ -183,6 +183,7 @@ struct sun4i_tfm_ctx {
 
 struct sun4i_cipher_req_ctx {
 	u32 mode;
+	u8 backup_iv[AES_BLOCK_SIZE];
 	struct skcipher_request fallback_req;   // keep at the end
 };