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Florian Westphal authored
Its possible that we have more than one packet with the same ct tuple simultaneously, e.g. when an application emits n packets on same UDP socket from multiple threads. NAT rules might be applied to those packets. With the right set of rules, n packets will be mapped to m destinations, where at least two packets end up with the same destination. When this happens, the existing clash resolution may merge the skb that is processed after the first has been received with the identical tuple already in hash table. However, its possible that this identical tuple is a NAT_CLASH tuple. In that case the second skb will be sent, but no reply can be received since the reply that is processed first removes the NAT_CLASH tuple. Do not auto-delete, this gives a 1 second window for replies to be passed back to originator. Packets that are coming later (udp stream case) will not be affected: they match the original ct entry, not a NAT_CLASH one. Also prevent NAT_CLASH entries from getting offloaded. Fixes: 6a757c07 ("netfilter: conntrack: allow insertion of clashing entries") Signed-off-by:
Florian Westphal <fw@strlen.de> Signed-off-by:
Pablo Neira Ayuso <pablo@netfilter.org>
c4617214