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);