netfilter: allow ipv6 fragments to arrive on different devices

[ Upstream commit 3cd740b9 ]

Commit 264640fc ("ipv6: distinguish frag queues by device
for multicast and link-local packets") modified the ipv6 fragment
reassembly logic to distinguish frag queues by device for multicast
and link-local packets but in fact only the main reassembly code
limits the use of the device to those address types and the netfilter
reassembly code uses the device for all packets.

This means that if fragments of a packet arrive on different interfaces
then netfilter will fail to reassemble them and the fragments will be
expired without going any further through the filters.

Fixes: 648700f7 ("inet: frags: use rhashtables for reassembly units")
Signed-off-by: Tom Hughes <tom@compton.nu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>