2019-06-14 22:02:18

by Dan Noland

[permalink] [raw]
Subject: fs_use_xattr question

- Hello -

I have a custom stacked filesystem and I was having difficulty with
security xattrs. I traced it back to missing:

fs_use_xattr myfs gen_context(system_u:object_r:fs_t,s0);

Which works nicely when I rebuild/reinstall the base policy. However
some experimentation and checking of old mailing posts seems to
indicate that it is not possible to achieve this in a policy module.

Because my FS is stacked I would be perfectly happy just to
inherit whatever the fs_use_xattr state of my lower filesystem is.

Is there a best practice for achieving this or do I need to always
rebuild the base policy?

Thank you for your time.

--
TY,
Dan Noland


2019-06-15 11:43:28

by Dominick Grift

[permalink] [raw]
Subject: Re: fs_use_xattr question

On Fri, Jun 14, 2019 at 10:01:52PM +0000, Dan Noland wrote:
> - Hello -
>
> I have a custom stacked filesystem and I was having difficulty with
> security xattrs. I traced it back to missing:
>
> fs_use_xattr myfs gen_context(system_u:object_r:fs_t,s0);
>
> Which works nicely when I rebuild/reinstall the base policy. However
> some experimentation and checking of old mailing posts seems to
> indicate that it is not possible to achieve this in a policy module.
>
> Because my FS is stacked I would be perfectly happy just to
> inherit whatever the fs_use_xattr state of my lower filesystem is.
>
> Is there a best practice for achieving this or do I need to always
> rebuild the base policy?

If you are able to use CIL then you might be able to do this:

echo '(fsuse xattr "myfs" (system_u object_r fs_t ((s0)(s0))))' > mytest.cil && sudo semodule -i mytest.cil

>
> Thank you for your time.
>
> --
> TY,
> Dan Noland

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Dominick Grift


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