Re: bpfilter breaks IPT_SO_GET_INFO

From: Michal Kubecek
Date: Wed Sep 19 2018 - 03:18:53 EST

On Mon, Sep 17, 2018 at 03:36:21PM +0200, Dmitry Vyukov wrote:
> Hi,
> I am having some problem with upstream kernel and bpfilter. The
> manifestation is that IPT_SO_GET_INFO on an ipv4 socket works, then
> something (that I can't fully localize but can reproduce) happens and
> then IPT_SO_GET_INFO starts permanently returning 256.
> Now the litmus program always fails with:
> getsockopt(3, SOL_IP, 0x40 /* IP_??? */,
> "filter\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., [84])
> = 256
> I am currently on upstream commit
> 28619527b8a712590c93d0a9e24b4425b9376a8c, my .config is attached. I
> don't know what is bpfilter, I see it mentions some umh, if it
> requires some additional setup I don't it, i.e. I don't install any
> userspace modules/helpers.

This looks similar to the fallback issue described here:

Unfortunately I didn't have time to look into it more closely yet.

Michal Kubecek