[Intel-wired-lan] [PATCH V2] ixgbe: Handle extended IPv6 headers in tx path

Rustad, Mark D mark.d.rustad at intel.com
Tue Nov 17 19:29:37 UTC 2015


Tom Herbert <tom at herbertland.com> wrote:

> This does not entirely fix the problem though. It is a valid use case
> that someone can send an UDP packet with an extension header that is
> unknown to ipv6_skip_exthdr. The driver can do a dev_warn if it wants
> to in this case I suppose, but sending out the packet without setting
> the checksum is incorrect. The rule is simple: if the drive cannot
> offload a checksum then call skb_checksum_help-- this as a default can
> never make matters worse.

I suppose there could be both a message and the call to skb_checksum_help. The only drawback to that is a rate-limited message spamming the log that might go unnoticed for some time because things "work". I don't know what the security wonks would think about unrecognized extended headers being generated by an application. Hmm. Is it really possible to use an extended header that the kernel doesn't know about? If the kernel knows about it, then ipv6_skip_exthdr should work.

If the consensus is to add the call, I don't have a strong objection, I just have some reservations about it.

--
Mark Rustad, Networking Division, Intel Corporation
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