crypto: crypto4xx - extend aead fallback checks

1020 bytes is the limit for associated data. Any more
and it will no longer fit into hash_crypto_offset anymore.

The hardware will not process aead requests with plaintext
that have less than AES_BLOCK_SIZE bytes. When decrypting
aead requests the authsize has to be taken in account as
well, as it is part of the cryptlen. Otherwise the hardware
will think it has been misconfigured and will return:

aead return err status = 0x98

For rtc4543(gcm(aes)), the hardware has a dedicated GMAC
mode as part of the hash function set.

Signed-off-by: Christian Lamparter <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>

drivers/crypto/amcc/crypto4xx_alg.c

@@ -321,6 +321,7 @@ int crypto4xx_decrypt_ctr(struct skcipher_request *req)
 }
 
 static inline bool crypto4xx_aead_need_fallback(struct aead_request *req,
+						unsigned int len,
 						bool is_ccm, bool decrypt)
 {
 	struct crypto_aead *aead = crypto_aead_reqtfm(req);
@@ -330,14 +331,14 @@ static inline bool crypto4xx_aead_need_fallback(struct aead_request *req,
 		return true;
 
 	/*
-	 * hardware does not handle cases where cryptlen
-	 * is less than a block
+	 * hardware does not handle cases where plaintext
+	 * is less than a block.
 	 */
-	if (req->cryptlen < AES_BLOCK_SIZE)
+	if (len < AES_BLOCK_SIZE)
 		return true;
 
-	/* assoc len needs to be a multiple of 4 */
-	if (req->assoclen & 0x3)
+	/* assoc len needs to be a multiple of 4 and <= 1020 */
+	if (req->assoclen & 0x3 || req->assoclen > 1020)
 		return true;
 
 	/* CCM supports only counter field length of 2 and 4 bytes */
@@ -449,17 +450,17 @@ static int crypto4xx_crypt_aes_ccm(struct aead_request *req, bool decrypt)
 {
 	struct crypto4xx_ctx *ctx  = crypto_tfm_ctx(req->base.tfm);
 	struct crypto_aead *aead = crypto_aead_reqtfm(req);
-	unsigned int len = req->cryptlen;
 	__le32 iv[16];
 	u32 tmp_sa[SA_AES128_CCM_LEN + 4];
 	struct dynamic_sa_ctl *sa = (struct dynamic_sa_ctl *)tmp_sa;
-
-	if (crypto4xx_aead_need_fallback(req, true, decrypt))
-		return crypto4xx_aead_fallback(req, ctx, decrypt);
+	unsigned int len = req->cryptlen;
 
 	if (decrypt)
 		len -= crypto_aead_authsize(aead);
 
+	if (crypto4xx_aead_need_fallback(req, len, true, decrypt))
+		return crypto4xx_aead_fallback(req, ctx, decrypt);
+
 	memcpy(tmp_sa, decrypt ? ctx->sa_in : ctx->sa_out, ctx->sa_len * 4);
 	sa->sa_command_0.bf.digest_len = crypto_aead_authsize(aead) >> 2;
 
@@ -605,18 +606,19 @@ static inline int crypto4xx_crypt_aes_gcm(struct aead_request *req,
 					  bool decrypt)
 {
 	struct crypto4xx_ctx *ctx = crypto_tfm_ctx(req->base.tfm);
-	unsigned int len = req->cryptlen;
+	struct crypto4xx_aead_reqctx *rctx = aead_request_ctx(req);
 	__le32 iv[4];
+	unsigned int len = req->cryptlen;
+
+	if (decrypt)
+		len -= crypto_aead_authsize(crypto_aead_reqtfm(req));
 
-	if (crypto4xx_aead_need_fallback(req, false, decrypt))
+	if (crypto4xx_aead_need_fallback(req, len, false, decrypt))
 		return crypto4xx_aead_fallback(req, ctx, decrypt);
 
 	crypto4xx_memcpy_to_le32(iv, req->iv, GCM_AES_IV_SIZE);
 	iv[3] = cpu_to_le32(1);
 
-	if (decrypt)
-		len -= crypto_aead_authsize(crypto_aead_reqtfm(req));
-
 	return crypto4xx_build_pd(&req->base, ctx, req->src, req->dst,
 				  len, iv, sizeof(iv),
 				  decrypt ? ctx->sa_in : ctx->sa_out,