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stephen hemminger authored
Linux tunnels were written before RFC6040 and therefore never implemented the corner case of ECN getting set in the outer header and the inner header not being ready for it. Section 4.2. Default Tunnel Egress Behaviour. o If the inner ECN field is Not-ECT, the decapsulator MUST NOT propagate any other ECN codepoint onwards. This is because the inner Not-ECT marking is set by transports that rely on dropped packets as an indication of congestion and would not understand or respond to any other ECN codepoint [RFC4774]. Specifically: * If the inner ECN field is Not-ECT and the outer ECN field is CE, the decapsulator MUST drop the packet. * If the inner ECN field is Not-ECT and the outer ECN field is Not-ECT, ECT(0), or ECT(1), the decapsulator MUST forward the outgoing packet with the ECN field cleared to Not-ECT. This patch moves the ECN decap logic out of the individual tunnels into a common place. It also adds logging to allow detecting broken systems that set ECN bits incorrectly when tunneling (or an intermediate router might be changing the header). Overloads rx_frame_error to keep track of ECN related error. Thanks to Chris Wright who caught this while reviewing the new VXLAN tunnel. This code was tested by injecting faulty logic in other end GRE to send incorrectly encapsulated packets. Signed-off-by:
Stephen Hemminger <shemminger@vyatta.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
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