net: fix TCP/UDP checksum with padding data

[ upstream commit e55ea3d5d970dfff2989e4a1c65b76d02512bce0 ]

IEEE 802 packets may have a minimum size limit. The data fields
should be padded when necessary. In some cases, the padding data
is not zero.

In 'rte_ipv4_udptcp_cksum_mbuf()', as payload length
"mbuf->pkt_len - l4_off" is used, which includes padding and if
padding is not zero it will end up producing wrong checksum.

This patch will use IP header to get the payload size to calculate
TCP/UDP checksum.

Fixes: d178f69 ("net: add UDP/TCP checksum in mbuf segments")

Signed-off-by: Kaiwen Deng <kaiwenx.deng@intel.com>
Reviewed-by: Morten Brørup <mb@smartsharesystems.com>

lib/net/rte_ip.h

@@ -420,11 +420,14 @@ __rte_ipv4_udptcp_cksum_mbuf(const struct rte_mbuf *m,
 {
 	uint16_t raw_cksum;
 	uint32_t cksum;
+	uint16_t len;
 
-	if (l4_off > m->pkt_len)
-		return 0;
+	if (unlikely(l4_off > m->pkt_len))
+		return 0; /* invalid params, return a dummy value */
+
+	len = rte_be_to_cpu_16(ipv4_hdr->total_length) - (uint16_t)rte_ipv4_hdr_len(ipv4_hdr);
 
-	if (rte_raw_cksum_mbuf(m, l4_off, m->pkt_len - l4_off, &raw_cksum))
+	if (rte_raw_cksum_mbuf(m, l4_off, len, &raw_cksum))
 		return 0;
 
 	cksum = raw_cksum + rte_ipv4_phdr_cksum(ipv4_hdr, 0);
@@ -650,10 +653,10 @@ __rte_ipv6_udptcp_cksum_mbuf(const struct rte_mbuf *m,
 	uint16_t raw_cksum;
 	uint32_t cksum;
 
-	if (l4_off > m->pkt_len)
-		return 0;
+	if (unlikely(l4_off > m->pkt_len))
+		return 0; /* invalid params, return a dummy value */
 
-	if (rte_raw_cksum_mbuf(m, l4_off, m->pkt_len - l4_off, &raw_cksum))
+	if (rte_raw_cksum_mbuf(m, l4_off, rte_be_to_cpu_16(ipv6_hdr->payload_len), &raw_cksum))
 		return 0;
 
 	cksum = raw_cksum + rte_ipv6_phdr_cksum(ipv6_hdr, 0);