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| author | Liping Zhang <zlpnobody@gmail.com> | 2017-01-07 20:49:18 +0800 |
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| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2017-01-16 14:23:01 +0100 |
| commit | 6443ebc3fdd6f3c766d9442c18be274b3d736050 (patch) | |
| tree | 3074af3b09ed120ad74198e669fad6464127d66e /include/uapi | |
| parent | d7f5762c5e532dfe8247ce1bc60d97af27ff8d00 (diff) | |
netfilter: rpfilter: fix incorrect loopback packet judgment
Currently, we check the existing rtable in PREROUTING hook, if RTCF_LOCAL
is set, we assume that the packet is loopback.
But this assumption is incorrect, for example, a packet encapsulated
in ipsec transport mode was received and routed to local, after
decapsulation, it would be delivered to local again, and the rtable
was not dropped, so RTCF_LOCAL check would trigger. But actually, the
packet was not loopback.
So for these normal loopback packets, we can check whether the in device
is IFF_LOOPBACK or not. For these locally generated broadcast/multicast,
we can check whether the skb->pkt_type is PACKET_LOOPBACK or not.
Finally, there's a subtle difference between nft fib expr and xtables
rpfilter extension, user can add the following nft rule to do strict
rpfilter check:
# nft add rule x y meta iif eth0 fib saddr . iif oif != eth0 drop
So when the packet is loopback, it's better to store the in device
instead of the LOOPBACK_IFINDEX, otherwise, after adding the above
nft rule, locally generated broad/multicast packets will be dropped
incorrectly.
Fixes: f83a7ea2075c ("netfilter: xt_rpfilter: skip locally generated broadcast/multicast, too")
Fixes: f6d0cbcf09c5 ("netfilter: nf_tables: add fib expression")
Signed-off-by: Liping Zhang <zlpnobody@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'include/uapi')