[BPF] conntrack more resistant to spurious RSTs #9692
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Not used for anything useful and not used by the bpf conntrack cleanup at all.
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When we see an RST on a connection, we mark the connection for cleanup from the conntrack table. That happens immediatelly when the connection becomes idle and the TCPResetSeen timeout expires (by default 40s). Not a huge problem for busy connections or connections with keepalive. Nevertheless, an attacker may taint connections and once the connections are removed from conntrack, the endpoints need to get into retransmittions and timeouts to close their ends. This change removes the taint if the connection sees traffic after the RST. First it extends the timeout to 2m and if there is still traffic, it removes the taint completely. This mechanism is not bullet-proof since and idle connection might still be GCed, but it reduces the possibility of connection breakage when there is a temporary hickup in the network. Also allows to reduce the RSTSeen timeout.
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fixes #9605
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