crypto: caam - Clamp AEAD SG list by input length

Currently caam assumes that the SG list contains exactly the number
of bytes required.  This assumption is incorrect.

Up until now this has been harmless.  However with the new AEAD
interface this now breaks as the AD SG list contains more bytes
than just the AD.

This patch fixes this by always clamping the AD SG list by the
specified AD length.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/caam/caamalg.c

@@ -2713,10 +2713,8 @@ static struct aead_edesc *aead_edesc_alloc(struct aead_request *req,
 	sec4_sg_index = 0;
 	if (!all_contig) {
 		if (!is_gcm) {
-			sg_to_sec4_sg(req->assoc,
-				      assoc_nents,
-				      edesc->sec4_sg +
-				      sec4_sg_index, 0);
+			sg_to_sec4_sg_len(req->assoc, req->assoclen,
+					  edesc->sec4_sg + sec4_sg_index);
 			sec4_sg_index += assoc_nents;
 		}
 
@@ -2725,10 +2723,8 @@ static struct aead_edesc *aead_edesc_alloc(struct aead_request *req,
 		sec4_sg_index += 1;
 
 		if (is_gcm) {
-			sg_to_sec4_sg(req->assoc,
-				      assoc_nents,
-				      edesc->sec4_sg +
-				      sec4_sg_index, 0);
+			sg_to_sec4_sg_len(req->assoc, req->assoclen,
+					  edesc->sec4_sg + sec4_sg_index);
 			sec4_sg_index += assoc_nents;
 		}
 
@@ -2953,8 +2949,8 @@ static struct aead_edesc *aead_giv_edesc_alloc(struct aead_givcrypt_request
 	sec4_sg_index = 0;
 	if (!(contig & GIV_SRC_CONTIG)) {
 		if (!is_gcm) {
-			sg_to_sec4_sg(req->assoc, assoc_nents,
-				      edesc->sec4_sg + sec4_sg_index, 0);
+			sg_to_sec4_sg_len(req->assoc, req->assoclen,
+					  edesc->sec4_sg + sec4_sg_index);
 			sec4_sg_index += assoc_nents;
 		}
 
@@ -2963,8 +2959,8 @@ static struct aead_edesc *aead_giv_edesc_alloc(struct aead_givcrypt_request
 		sec4_sg_index += 1;
 
 		if (is_gcm) {
-			sg_to_sec4_sg(req->assoc, assoc_nents,
-				      edesc->sec4_sg + sec4_sg_index, 0);
+			sg_to_sec4_sg_len(req->assoc, req->assoclen,
+					  edesc->sec4_sg + sec4_sg_index);
 			sec4_sg_index += assoc_nents;
 		}
 

drivers/crypto/caam/sg_sw_sec4.h

@@ -55,6 +55,21 @@ static inline void sg_to_sec4_sg_last(struct scatterlist *sg, int sg_count,
 	sec4_sg_ptr->len |= SEC4_SG_LEN_FIN;
 }
 
+static inline struct sec4_sg_entry *sg_to_sec4_sg_len(
+	struct scatterlist *sg, unsigned int total,
+	struct sec4_sg_entry *sec4_sg_ptr)
+{
+	do {
+		unsigned int len = min(sg_dma_len(sg), total);
+
+		dma_to_sec4_sg_one(sec4_sg_ptr, sg_dma_address(sg), len, 0);
+		sec4_sg_ptr++;
+		sg = sg_next(sg);
+		total -= len;
+	} while (total);
+	return sec4_sg_ptr - 1;
+}
+
 /* count number of elements in scatterlist */
 static inline int __sg_count(struct scatterlist *sg_list, int nbytes,
 			     bool *chained)