net: flow: Add l3mdev flow update

Add l3mdev hook to set FLOWI_FLAG_SKIP_NH_OIF flag and update oif/iif
in flow struct if its oif or iif points to a device enslaved to an L3
Master device. Only 1 needs to be converted to match the l3mdev FIB
rule. This moves the flow adjustment for l3mdev to a single point
catching all lookups. It is redundant for existing hooks (those are
removed in later patches) but is needed for missed lookups such as
PMTU updates.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 35 insertions, 0 deletions

diff --git a/net/l3mdev/l3mdev.c b/net/l3mdev/l3mdev.c
index c4a1c3e84e12..43610e5acc4e 100644
--- a/net/l3mdev/l3mdev.c
+++ b/net/l3mdev/l3mdev.c
@@ -222,3 +222,38 @@ out:
 
 	return rc;
 }
+
+void l3mdev_update_flow(struct net *net, struct flowi *fl)
+{
+	struct net_device *dev;
+	int ifindex;
+
+	rcu_read_lock();
+
+	if (fl->flowi_oif) {
+		dev = dev_get_by_index_rcu(net, fl->flowi_oif);
+		if (dev) {
+			ifindex = l3mdev_master_ifindex_rcu(dev);
+			if (ifindex) {
+				fl->flowi_oif = ifindex;
+				fl->flowi_flags |= FLOWI_FLAG_SKIP_NH_OIF;
+				goto out;
+			}
+		}
+	}
+
+	if (fl->flowi_iif) {
+		dev = dev_get_by_index_rcu(net, fl->flowi_iif);
+		if (dev) {
+			ifindex = l3mdev_master_ifindex_rcu(dev);
+			if (ifindex) {
+				fl->flowi_iif = ifindex;
+				fl->flowi_flags |= FLOWI_FLAG_SKIP_NH_OIF;
+			}
+		}
+	}
+
+out:
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(l3mdev_update_flow);