Florian Westphal 10568f6c57 netfilter: xt_checksum: ignore gso skbs
Satish Patel reports a skb_warn_bad_offload() splat caused
by -j CHECKSUM rules:

-A POSTROUTING -p tcp -m tcp --sport 80 -j CHECKSUM

The CHECKSUM target has never worked with GSO skbs, and the above rule
makes no sense as kernel will handle checksum updates on transmit.

Unfortunately, there are 3rd party tools that install such rules, so we
cannot reject this from the config plane without potential breakage.

Amend Kconfig text to clarify that the CHECKSUM target is only useful
in virtualized environments, where old dhcp clients that use AF_PACKET
used to discard UDP packets with a 'bad' header checksum and add a
one-time warning in case such rule isn't restricted to UDP.

v2: check IP6T_F_PROTO flag before cmp (Michal Kubecek)

Reported-by: Satish Patel <satish.txt@gmail.com>
Reported-by: Markos Chandras <markos.chandras@suse.com>
Reported-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2018-08-24 09:58:16 +02:00
2018-08-19 10:38:36 -07:00
2018-08-14 10:23:25 -07:00
2018-08-18 15:55:59 -07:00
2018-08-18 11:44:53 -07:00
2018-08-18 15:55:59 -07:00
2018-08-19 10:38:36 -07:00
2018-04-15 17:21:30 -07:00
2017-11-17 17:45:29 -08:00
2018-08-15 12:50:10 -07:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
Description
Linux kernel stable tree
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