net: vrf: Implement get_saddr for IPv6

IPv6 source address selection needs to consider the real egress route.
Similar to IPv4 implement a get_saddr6 method which is called if
source address has not been set.  The get_saddr6 method does a full
lookup which means pulling a route from the VRF FIB table and properly
considering linklocal/multicast destination addresses. Lookup failures
(eg., unreachable) then cause the source address selection to fail
which gets propagated back to the caller.

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

1 files changed, 24 insertions, 0 deletions

diff --git a/net/l3mdev/l3mdev.c b/net/l3mdev/l3mdev.c
index d90e4ef09e85..c4a1c3e84e12 100644
--- a/net/l3mdev/l3mdev.c
+++ b/net/l3mdev/l3mdev.c
@@ -162,6 +162,30 @@ int l3mdev_get_saddr(struct net *net, int ifindex, struct flowi4 *fl4)
 }
 EXPORT_SYMBOL_GPL(l3mdev_get_saddr);
 
+int l3mdev_get_saddr6(struct net *net, const struct sock *sk,
+                      struct flowi6 *fl6)
+{
+        struct net_device *dev;
+        int rc = 0;
+
+        if (fl6->flowi6_oif) {
+                rcu_read_lock();
+
+                dev = dev_get_by_index_rcu(net, fl6->flowi6_oif);
+                if (dev && netif_is_l3_slave(dev))
+                        dev = netdev_master_upper_dev_get_rcu(dev);
+
+                if (dev && netif_is_l3_master(dev) &&
+                    dev->l3mdev_ops->l3mdev_get_saddr6)
+                        rc = dev->l3mdev_ops->l3mdev_get_saddr6(dev, sk, fl6);
+
+                rcu_read_unlock();
+        }
+
+        return rc;
+}
+EXPORT_SYMBOL_GPL(l3mdev_get_saddr6);
+
 /**
  *      l3mdev_fib_rule_match - Determine if flowi references an
  *                              L3 master device