Differential D20147

Remove non-functional SCTP checksum offload support for virtio
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Authored by tuexen on May 3 2019, 1:45 PM.

Details

Reviewers

bryanv
philip

Commits

rS347233: Remove non-functional SCTP checksum offload support for virtio.

Summary

Checksum offloading for SCTP is not currently specified for virtio. If the hypervisor announces checksum offloading support, it means TCP and UDP checksum offload. If an SCTP packet is sent and the host announced checksum offload support, the hypervisor inserts the IP checksum (16-bit) at the correct offset, but this is not the right checksum, which is a CRC32c. This results in all outgoing packets having the wrong checksum and therefore breaking SCTP based communications.

This patch removes SCTP checksum offloading support from the virtio network interface.

Thanks to Felix Weinrank for making me aware of the issue.

Test Plan

It can be tested with running

ncat --sctp bsd14.fh-muenster.de

Diff Detail

Repository

rS FreeBSD src repository - subversion

Lint

Lint Not Applicable

Unit

Tests Not Applicable

Event Timeline

tuexen created this revision.May 3 2019, 1:45 PM

Herald added a subscriber: imp. · View Herald TranscriptMay 3 2019, 1:45 PM

Harbormaster completed remote builds in B24084: Diff 57003.May 3 2019, 1:45 PM

This is fine. I made a similar change in my VirtIO V1 branch (https://github.com/bryanv/freebsd/commit/a2903365a44b710929e52bf00b85a501856a7510) but I have not had the time to commit it yet.

This revision is now accepted and ready to land.May 7 2019, 3:06 PM

bryanv added inline comments.May 7 2019, 3:07 PM

sys/dev/virtio/network/if_vtnetvar.h
271 ↗	(On Diff #57003)	Nit: this comment could probably be removed since it is kind of implied.

Closed by commit rS347233: Remove non-functional SCTP checksum offload support for virtio. (authored by tuexen). · Explain WhyMay 7 2019, 8:28 PM

This revision was automatically updated to reflect the committed changes.

tuexen marked an inline comment as done.

tuexen added inline comments.May 7 2019, 8:29 PM

sys/dev/virtio/network/if_vtnetvar.h
271 ↗	(On Diff #57003)	OK. I removed the comment. Just wanted to make sure SCTP doesn't get added again by accident. But we now have the an entry in the svn log making it clear.

Revision Contents
Changeset List

Path

Size

head/

sys/

dev/

virtio/

network/

if_vtnet.c

9 lines

if_vtnetvar.h

4 lines

Diff 57145

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head/sys/dev/virtio/network/if_vtnet.c