bpf: host: also handle from-egress proxy traffic #30095
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Once forward traffic for an egress proxy connection has traversed through
cilium_host / cilium_net, we expect IPsec-marked packets to get handled
by xfrm. But this currently conflicts with an iptables rule for the
proxy's transparent socket, which then over-writes the mark:
-A CILIUM_PRE_mangle -m socket --transparent -m comment --comment "cilium: any->pod redirect proxied traffic to host proxy" -j MARK --set-xmark 0x200/0xffffffff
We can avoid this by adding an extra filter to this rule, so that it
doesn't match IPsec-marked packets.
Signed-off-by: Zhichuan Liang<gray.liang@isovalent.com>
After forward traffic for an egress proxy onnection has traversed through cilium_host / cilium_net, we expect IPsec-marked packets to get handled by xfrm. This currently conflicts with early demux, which matches the connection's transparent socket and assigns it to the packet: ``` // https://elixir.bootlin.com/linux/v6.2/source/net/ipv4/tcp_ipv4.c#L1770 int tcp_v4_early_demux(struct sk_buff *skb) { ... sk = __inet_lookup_established(net, net->ipv4.tcp_death_row.hashinfo, iph->saddr, th->source, iph->daddr, ntohs(th->dest), skb->skb_iif, inet_sdif(skb)); if (sk) { skb->sk = sk; ... } ``` It then gets dropped in ip_forward(), before reaching xfrm: ``` // https://elixir.bootlin.com/linux/v6.2/source/net/ipv4/ip_forward.c#L100 int ip_forward(struct sk_buff *skb) { ... if (unlikely(skb->sk)) goto drop; ... } ``` To avoid this we disable early-demux in a L7 + IPsec config. Note that the L7 proxy feature needs to deal with similar troubles, as the comment for inboundProxyRedirectRule() describes. Ideally we would build a similar solution for IPsec, diverting traffic with policy routing so that it doesn't get intercepted by early-demux. Signed-off-by: Zhichuan Liang<gray.liang@isovalent.com> Signed-off-by: Julian Wiedmann <jwi@isovalent.com>
The from-host path already knows how to handle traffic that comes from the ingress proxy. Extend this logic to also cover traffic that originates from the egress proxy. Signed-off-by: Zhichuan Liang <gray.liang@isovalent.com> Signed-off-by: Julian Wiedmann <jwi@isovalent.com>
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