crypto: arm64/aes-cts-cbc - move request context data to the stack

Since the CTS-CBC code completes synchronously, there is no point in
keeping part of the scratch data it uses in the request context, so
move it to the stack instead.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/arm64/crypto/aes-glue.c

@@ -107,12 +107,6 @@ asmlinkage void aes_mac_update(u8 const in[], u32 const rk[], int rounds,
 			       int blocks, u8 dg[], int enc_before,
 			       int enc_after);
 
-struct cts_cbc_req_ctx {
-	struct scatterlist sg_src[2];
-	struct scatterlist sg_dst[2];
-	struct skcipher_request subreq;
-};
-
 struct crypto_aes_xts_ctx {
 	struct crypto_aes_ctx key1;
 	struct crypto_aes_ctx __aligned(8) key2;
@@ -292,23 +286,20 @@ static int __maybe_unused cbc_decrypt(struct skcipher_request *req)
 	return cbc_decrypt_walk(req, &walk);
 }
 
-static int cts_cbc_init_tfm(struct crypto_skcipher *tfm)
-{
-	crypto_skcipher_set_reqsize(tfm, sizeof(struct cts_cbc_req_ctx));
-	return 0;
-}
-
 static int cts_cbc_encrypt(struct skcipher_request *req)
 {
 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 	struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
-	struct cts_cbc_req_ctx *rctx = skcipher_request_ctx(req);
 	int err, rounds = 6 + ctx->key_length / 4;
 	int cbc_blocks = DIV_ROUND_UP(req->cryptlen, AES_BLOCK_SIZE) - 2;
 	struct scatterlist *src = req->src, *dst = req->dst;
+	struct scatterlist sg_src[2], sg_dst[2];
+	struct skcipher_request subreq;
 	struct skcipher_walk walk;
 
-	skcipher_request_set_tfm(&rctx->subreq, tfm);
+	skcipher_request_set_tfm(&subreq, tfm);
+	skcipher_request_set_callback(&subreq, skcipher_request_flags(req),
+				      NULL, NULL);
 
 	if (req->cryptlen <= AES_BLOCK_SIZE) {
 		if (req->cryptlen < AES_BLOCK_SIZE)
@@ -317,31 +308,30 @@ static int cts_cbc_encrypt(struct skcipher_request *req)
 	}
 
 	if (cbc_blocks > 0) {
-		skcipher_request_set_crypt(&rctx->subreq, req->src, req->dst,
+		skcipher_request_set_crypt(&subreq, req->src, req->dst,
 					   cbc_blocks * AES_BLOCK_SIZE,
 					   req->iv);
 
-		err = skcipher_walk_virt(&walk, &rctx->subreq, false) ?:
-		      cbc_encrypt_walk(&rctx->subreq, &walk);
+		err = skcipher_walk_virt(&walk, &subreq, false) ?:
+		      cbc_encrypt_walk(&subreq, &walk);
 		if (err)
 			return err;
 
 		if (req->cryptlen == AES_BLOCK_SIZE)
 			return 0;
 
-		dst = src = scatterwalk_ffwd(rctx->sg_src, req->src,
-					     rctx->subreq.cryptlen);
+		dst = src = scatterwalk_ffwd(sg_src, req->src, subreq.cryptlen);
 		if (req->dst != req->src)
-			dst = scatterwalk_ffwd(rctx->sg_dst, req->dst,
-					       rctx->subreq.cryptlen);
+			dst = scatterwalk_ffwd(sg_dst, req->dst,
+					       subreq.cryptlen);
 	}
 
 	/* handle ciphertext stealing */
-	skcipher_request_set_crypt(&rctx->subreq, src, dst,
+	skcipher_request_set_crypt(&subreq, src, dst,
 				   req->cryptlen - cbc_blocks * AES_BLOCK_SIZE,
 				   req->iv);
 
-	err = skcipher_walk_virt(&walk, &rctx->subreq, false);
+	err = skcipher_walk_virt(&walk, &subreq, false);
 	if (err)
 		return err;
 
@@ -357,13 +347,16 @@ static int cts_cbc_decrypt(struct skcipher_request *req)
 {
 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 	struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
-	struct cts_cbc_req_ctx *rctx = skcipher_request_ctx(req);
 	int err, rounds = 6 + ctx->key_length / 4;
 	int cbc_blocks = DIV_ROUND_UP(req->cryptlen, AES_BLOCK_SIZE) - 2;
 	struct scatterlist *src = req->src, *dst = req->dst;
+	struct scatterlist sg_src[2], sg_dst[2];
+	struct skcipher_request subreq;
 	struct skcipher_walk walk;
 
-	skcipher_request_set_tfm(&rctx->subreq, tfm);
+	skcipher_request_set_tfm(&subreq, tfm);
+	skcipher_request_set_callback(&subreq, skcipher_request_flags(req),
+				      NULL, NULL);
 
 	if (req->cryptlen <= AES_BLOCK_SIZE) {
 		if (req->cryptlen < AES_BLOCK_SIZE)
@@ -372,31 +365,30 @@ static int cts_cbc_decrypt(struct skcipher_request *req)
 	}
 
 	if (cbc_blocks > 0) {
-		skcipher_request_set_crypt(&rctx->subreq, req->src, req->dst,
+		skcipher_request_set_crypt(&subreq, req->src, req->dst,
 					   cbc_blocks * AES_BLOCK_SIZE,
 					   req->iv);
 
-		err = skcipher_walk_virt(&walk, &rctx->subreq, false) ?:
-		      cbc_decrypt_walk(&rctx->subreq, &walk);
+		err = skcipher_walk_virt(&walk, &subreq, false) ?:
+		      cbc_decrypt_walk(&subreq, &walk);
 		if (err)
 			return err;
 
 		if (req->cryptlen == AES_BLOCK_SIZE)
 			return 0;
 
-		dst = src = scatterwalk_ffwd(rctx->sg_src, req->src,
-					     rctx->subreq.cryptlen);
+		dst = src = scatterwalk_ffwd(sg_src, req->src, subreq.cryptlen);
 		if (req->dst != req->src)
-			dst = scatterwalk_ffwd(rctx->sg_dst, req->dst,
-					       rctx->subreq.cryptlen);
+			dst = scatterwalk_ffwd(sg_dst, req->dst,
+					       subreq.cryptlen);
 	}
 
 	/* handle ciphertext stealing */
-	skcipher_request_set_crypt(&rctx->subreq, src, dst,
+	skcipher_request_set_crypt(&subreq, src, dst,
 				   req->cryptlen - cbc_blocks * AES_BLOCK_SIZE,
 				   req->iv);
 
-	err = skcipher_walk_virt(&walk, &rctx->subreq, false);
+	err = skcipher_walk_virt(&walk, &subreq, false);
 	if (err)
 		return err;
 
@@ -673,7 +665,6 @@ static struct skcipher_alg aes_algs[] = { {
 	.setkey		= skcipher_aes_setkey,
 	.encrypt	= cts_cbc_encrypt,
 	.decrypt	= cts_cbc_decrypt,
-	.init		= cts_cbc_init_tfm,
 }, {
 	.base = {
 		.cra_name		= "__essiv(cbc(aes),sha256)",