The hardware checksum code makes the assumption that a packet routed out

a particular Ethernet interface will actually be delivered by (only) that
device driver. This is not necessarily true when ng_ether(4) is used.

To word around this, while a ng_ether(4)'s "upper" hook is connected,
turn off all hardware checksum, fragmentation, etc., features for that
interface.

PR:		kern/31586
MFC after:	1 week

1 files changed, 9 insertions, 2 deletions

diff --git a/sys/netgraph/ng_ether.c b/sys/netgraph/ng_ether.c
index a3c14e9..0050bdd 100644
--- a/sys/netgraph/ng_ether.c
+++ b/sys/netgraph/ng_ether.c
@@ -75,6 +75,7 @@ struct private {
 	u_char		lowerOrphan;	/* whether lower is lower or orphan */
 	u_char		autoSrcAddr;	/* always overwrite source address */
 	u_char		promisc;	/* promiscuous mode enabled */
+	u_long		hwassist;	/* hardware checksum capabilities */
 	u_int		flags;		/* flags e.g. really die */
 };
 typedef struct private *priv_p;
@@ -317,6 +318,7 @@ ng_ether_attach(struct ifnet *ifp)
 	priv->ifp = ifp;
 	IFP2NG(ifp) = node;
 	priv->autoSrcAddr = 1;
+	priv->hwassist = ifp->if_hwassist;
 
 	/* Try to give the node the same name as the interface */
 	if (ng_name_node(node, name) != 0) {
@@ -468,6 +470,10 @@ ng_ether_newhook(node_p node, hook_p hook, const char *name)
 	if (*hookptr != NULL)
 		return (EISCONN);
 
+	/* Disable hardware checksums while 'upper' hook is connected */
+	if (hookptr == &priv->upper)
+		priv->ifp->if_hwassist = 0;
+
 	/* OK */
 	*hookptr = hook;
 	priv->lowerOrphan = orphan;
@@ -715,9 +721,10 @@ ng_ether_disconnect(hook_p hook)
 {
 	const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
 
-	if (hook == priv->upper)
+	if (hook == priv->upper) {
 		priv->upper = NULL;
-	else if (hook == priv->lower) {
+		priv->ifp->if_hwassist = priv->hwassist;  /* restore h/w csum */
+	} else if (hook == priv->lower) {
 		priv->lower = NULL;
 		priv->lowerOrphan = 0;
 	} else