bpf: nodeport: update TTL / hop-limit on redirect #27299
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When forwarding from the XDP LB to a remote NAT backend, tail_nodeport_nat_egress_ipv4() potentially adds outer tunnel headers to the packet. The call to fib_redirect_v4() then decrements outer header's TTL, not the inner IPv4 header. Fix this by manually updating the TTL, and open-coding the redirect. Signed-off-by: Julian Wiedmann <jwi@isovalent.com>
When forwarding from the LB to a remote NAT backend, tail_nodeport_nat_egress_ipv6() uses fib_redirect() to pick the egress interface (we can't use fib_redirect_v6() as the packet might have been converted to IPv4, or tunnel-encapsulated in XDP). Thus the hop-limit currently doesn't get updated. Do so manually, before potentially adding the tunnel encapsulation. Signed-off-by: Julian Wiedmann <jwi@isovalent.com>
When forwarding replies from the LB (or EgressGW replies) back to the client, rev_nodeport_lb4() potentially adds outer tunnel headers to the packet. The call to fib_redirect_v4() then decrements outer header's TTL, not the inner IPv4 header. Fix this by manually updating the TTL, and open-coding the redirect. Signed-off-by: Julian Wiedmann <jwi@isovalent.com>
When forwarding replies from the LB back to the client, rev_nodeport_lb6() uses fib_redirect() to pick the egress interface (we can't use fib_redirect_v6() as the packet might have been converted to IPv4, or tunnel-encapsulated in XDP). Thus the hop-limit currently doesn't get updated. Do so manually. Signed-off-by: Julian Wiedmann <jwi@isovalent.com>
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#23884 and #24422 introduced some inconsistencies and bugs in how the TTL / hop-limit field is updated when a packet is redirected from the ingress path to a remote destination. Fix them by adding
ipv*_l3()calls, or shuffling the existing calls into the correct place.