Re: [PATCH PLACEHOLDER 1/3] fs/exec: "always_unprivileged" patch

[Andrew Lutomirski]

On Thu, Jan 12, 2012 at 5:37 PM, Will Drewry <wad@xxxxxxxxxxxx> wrote:
> On Thu, Jan 12, 2012 at 7:11 PM, Andrew Lutomirski <luto@xxxxxxx> wrote:
>> (Also, preventing dropping of privileges will probably make a patch
>> more complicted -- I'll have to find and update all the places that
>> allow dropping privileges.)
>
> An alternative approach might be that the restricted bit drops all
> privileges that allows privilege changes in either direction.  E.g.,
> - set restricted bit
> -- adds a check anywhere MNT_NOSUID is
> -- sets securebit to SECURE_NOROOT|..LOCKED
> -- drops CAP_SETUID, CAP_DAC_OVERRIDE, ...
> -- set the caps bounding set to the minimum the restricted bit allows
>
> That may deviate from the intent (by re-using caps), but it could keep some
> of the privilege transition checking code the same.

I'm not sure it'll be much of a simplification.  The entire patch is
45 lines right now :)  I'll test it and send it out.

FWIW, though, it breaks apparmor (intentionally).  Can any of you
either explain what *should* happen or (better) volunteer to fix it?
It should be about three lines of code for someone who understands
what's going on.  I don't have an apparmor system, so I can't really
test it.

--Andy

>
> Just a thought,
> will
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/