[dpdk-dev] [PATCH] examples/l2fwd-crypto: fix incorrect padding addition

[Pablo de Lara <pablo.de.lara.guarch@intel.com>]

L2fwd-crypto app was padding an incoming buffer,
to be aligned with the algorithm block size, in all cases.
This was not the right approach, as padding is only necessary
when using block cipher algorithms, such as AES-CBC.
In case of using a stream cipher algorithm, such as SNOW3G UEA2,
there is no need to include padding and increase the buffer size.

Fixes: 387259bd6c67 ("examples/l2fwd-crypto: add sample application")

Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
---
 examples/l2fwd-crypto/main.c | 36 +++++++++++++++++++++++++++---------
 1 file changed, 27 insertions(+), 9 deletions(-)

diff --git a/examples/l2fwd-crypto/main.c b/examples/l2fwd-crypto/main.c
index 43fef59..320fb0b 100644
--- a/examples/l2fwd-crypto/main.c
+++ b/examples/l2fwd-crypto/main.c
@@ -432,7 +432,8 @@ l2fwd_simple_crypto_enqueue(struct rte_mbuf *m,
 	struct ether_hdr *eth_hdr;
 	struct ipv4_hdr *ip_hdr;
 
-	unsigned ipdata_offset, pad_len, data_len;
+	uint32_t ipdata_offset, data_len;
+	uint32_t pad_len = 0;
 	char *padding;
 
 	eth_hdr = rte_pktmbuf_mtod(m, struct ether_hdr *);
@@ -455,16 +456,33 @@ l2fwd_simple_crypto_enqueue(struct rte_mbuf *m,
 	if (cparams->do_hash && cparams->hash_verify)
 		data_len -= cparams->digest_length;
 
-	pad_len = data_len % cparams->block_size ? cparams->block_size -
-			(data_len % cparams->block_size) : 0;
+	if (cparams->do_cipher) {
+		/*
+		 * Following algorithms are block cipher algorithms,
+		 * and might need padding
+		 */
+		switch (cparams->cipher_algo) {
+		case RTE_CRYPTO_CIPHER_AES_CBC:
+		case RTE_CRYPTO_CIPHER_AES_ECB:
+		case RTE_CRYPTO_CIPHER_DES_CBC:
+		case RTE_CRYPTO_CIPHER_3DES_CBC:
+		case RTE_CRYPTO_CIPHER_3DES_ECB:
+			if (data_len % cparams->block_size)
+				pad_len = cparams->block_size -
+					(data_len % cparams->block_size);
+			break;
+		default:
+			pad_len = 0;
+		}
 
-	if (pad_len) {
-		padding = rte_pktmbuf_append(m, pad_len);
-		if (unlikely(!padding))
-			return -1;
+		if (pad_len) {
+			padding = rte_pktmbuf_append(m, pad_len);
+			if (unlikely(!padding))
+				return -1;
 
-		data_len += pad_len;
-		memset(padding, 0, pad_len);
+			data_len += pad_len;
+			memset(padding, 0, pad_len);
+		}
 	}
 
 	/* Set crypto operation data parameters */
-- 
2.7.4