net/mlx4_en: don't set CHECKSUM_COMPLETE on SCTP packets

if the NIC fails to validate the checksum on TCP/UDP, and validation of IP
checksum is successful, the driver subtracts the pseudo-header checksum
from the value obtained by the hardware and sets CHECKSUM_COMPLETE. Don't
do that if protocol is IPPROTO_SCTP, otherwise CRC32c validation fails.

V2: don't test MLX4_CQE_STATUS_IPV6 if MLX4_CQE_STATUS_IPV4 is set

Reported-by: Shuang Li <[e-mail]>
Fixes: f8c6455bb04b ("net/mlx4_en: Extend checksum offloading by CHECKSUM COMPLETE")
Signed-off-by: Davide Caratti <[e-mail]>
Acked-by: Saeed Mahameed <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/mellanox/mlx4/en_rx.c

···
  * header, the HW adds it. To address that, we are subtracting the pseudo
  * header checksum from the checksum value provided by the HW.
  */
-static void get_fixed_ipv4_csum(__wsum hw_checksum, struct sk_buff *skb,
-				struct iphdr *iph)
+static int get_fixed_ipv4_csum(__wsum hw_checksum, struct sk_buff *skb,
+			       struct iphdr *iph)
 {
 	__u16 length_for_csum = 0;
 	__wsum csum_pseudo_header = 0;
+	__u8 ipproto = iph->protocol;
+
+	if (unlikely(ipproto == IPPROTO_SCTP))
+		return -1;
 
 	length_for_csum = (be16_to_cpu(iph->tot_len) - (iph->ihl << 2));
 	csum_pseudo_header = csum_tcpudp_nofold(iph->saddr, iph->daddr,
-						length_for_csum, iph->protocol, 0);
+						length_for_csum, ipproto, 0);
 	skb->csum = csum_sub(hw_checksum, csum_pseudo_header);
+	return 0;
 }
 
 #if IS_ENABLED(CONFIG_IPV6)
···
 static int get_fixed_ipv6_csum(__wsum hw_checksum, struct sk_buff *skb,
 			       struct ipv6hdr *ipv6h)
 {
+	__u8 nexthdr = ipv6h->nexthdr;
 	__wsum csum_pseudo_hdr = 0;
 
-	if (unlikely(ipv6h->nexthdr == IPPROTO_FRAGMENT ||
-		     ipv6h->nexthdr == IPPROTO_HOPOPTS))
+	if (unlikely(nexthdr == IPPROTO_FRAGMENT ||
+		     nexthdr == IPPROTO_HOPOPTS ||
+		     nexthdr == IPPROTO_SCTP))
 		return -1;
-	hw_checksum = csum_add(hw_checksum, (__force __wsum)htons(ipv6h->nexthdr));
+	hw_checksum = csum_add(hw_checksum, (__force __wsum)htons(nexthdr));
 
 	csum_pseudo_hdr = csum_partial(&ipv6h->saddr,
 				       sizeof(ipv6h->saddr) + sizeof(ipv6h->daddr), 0);
 	csum_pseudo_hdr = csum_add(csum_pseudo_hdr, (__force __wsum)ipv6h->payload_len);
-	csum_pseudo_hdr = csum_add(csum_pseudo_hdr, (__force __wsum)ntohs(ipv6h->nexthdr));
+	csum_pseudo_hdr = csum_add(csum_pseudo_hdr,
+				   (__force __wsum)htons(nexthdr));
 
 	skb->csum = csum_sub(hw_checksum, csum_pseudo_hdr);
 	skb->csum = csum_add(skb->csum, csum_partial(ipv6h, sizeof(struct ipv6hdr), 0));
···
 	}
 
 	if (cqe->status & cpu_to_be16(MLX4_CQE_STATUS_IPV4))
-		get_fixed_ipv4_csum(hw_checksum, skb, hdr);
+		return get_fixed_ipv4_csum(hw_checksum, skb, hdr);
 #if IS_ENABLED(CONFIG_IPV6)
-	else if (cqe->status & cpu_to_be16(MLX4_CQE_STATUS_IPV6))
-		if (unlikely(get_fixed_ipv6_csum(hw_checksum, skb, hdr)))
-			return -1;
+	if (cqe->status & cpu_to_be16(MLX4_CQE_STATUS_IPV6))
+		return get_fixed_ipv6_csum(hw_checksum, skb, hdr);
 #endif
 	return 0;
 }