net: restore ip source validation

when using policy routing and the skb mark:
there are cases where a back path validation requires us
to use a different routing table for src ip validation than
the one used for mapping ingress dst ip.
One such a case is transparent proxying where we pretend to be
the destination system and therefore the local table
is used for incoming packets but possibly a main table would
be used on outbound.
Make the default behavior to allow the above and if users
need to turn on the symmetry via sysctl src_valid_mark

Signed-off-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 877ba039e6a4..bd27fbc9db62 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -482,6 +482,7 @@ enum
         NET_IPV4_CONF_ARP_ACCEPT=21,
         NET_IPV4_CONF_ARP_NOTIFY=22,
         NET_IPV4_CONF_ACCEPT_LOCAL=23,
+        NET_IPV4_CONF_SRC_VMARK=24,
         __NET_IPV4_CONF_MAX
 };