net: ipv4: route: Fix sending IGMP messages with link address
In setups with a global scope address on an interface, and a lesser
scope address on an interface sending IGMP reports, the reports can be
sent using the other interfaces global scope address rather than the
local interface address. RFC 2236 suggests:
Ignore the Report if you cannot identify the source address of
the packet as belonging to a subnet assigned to the interface on
which the packet was received.
since such reports could be forged.
Look at the protocol when deciding if a RT_SCOPE_LINK address should
be used for the packet.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 7cad0bf..9e15f5c 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2091,7 +2091,8 @@
goto out;
}
if (ipv4_is_local_multicast(fl4->daddr) ||
- ipv4_is_lbcast(fl4->daddr)) {
+ ipv4_is_lbcast(fl4->daddr) ||
+ fl4->flowi4_proto == IPPROTO_IGMP) {
if (!fl4->saddr)
fl4->saddr = inet_select_addr(dev_out, 0,
RT_SCOPE_LINK);