esp: check the NETIF_F_HW_ESP_TX_CSUM bit before segmenting

If I understand correctly, we should not be asking for a
checksum offload on an ipsec packet if the netdev isn't
advertising NETIF_F_HW_ESP_TX_CSUM.  In that case, we should
clear the NETIF_F_CSUM_MASK bits.

Signed-off-by: Shannon Nelson <shannon.nelson@oracle.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/ipv4/esp4_offload.c

@@ -138,6 +138,8 @@ static struct sk_buff *esp4_gso_segment(struct sk_buff *skb,
 	if (!(features & NETIF_F_HW_ESP) || !x->xso.offload_handle ||
 	    (x->xso.dev != skb->dev))
 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
+	else if (!(features & NETIF_F_HW_ESP_TX_CSUM))
+		esp_features = features & ~NETIF_F_CSUM_MASK;
 
 	xo->flags |= XFRM_GSO_SEGMENT;
 

net/ipv6/esp6_offload.c

@@ -165,6 +165,8 @@ static struct sk_buff *esp6_gso_segment(struct sk_buff *skb,
 	if (!(features & NETIF_F_HW_ESP) || !x->xso.offload_handle ||
 	    (x->xso.dev != skb->dev))
 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
+	else if (!(features & NETIF_F_HW_ESP_TX_CSUM))
+		esp_features = features & ~NETIF_F_CSUM_MASK;
 
 	xo->flags |= XFRM_GSO_SEGMENT;