Re: [PATCH v8 3/8] security/brute: Detect a brute force attack

[John Wood]

Hi,

On Fri, Jul 02, 2021 at 05:08:09PM +0000, Alexander Lobakin wrote:
>
> On the other hand, it leaves a potentional window for attackers to
> perform brute force from xattr-incapable filesystems. So at the end
> of the day I think that the current implementation (a strong
> rejection of such filesystems) is way more secure than having
> a fallback I proposed.

I've been thinking more about this: that the Brute LSM depends on xattr
support and I don't like this part. I want that brute force attacks can
be detected and mitigated on every system (with minimal dependencies).
So, now I am working in a solution without this drawback. I have some
ideas but I need to work on it.

> I'm planning to make a patch which will eliminate such weird rootfs
> type selection and just always use more feature-rich tmpfs if it's
> compiled in. So, as an alternative, you could add it to your series
> as a preparatory change and just add a Kconfig dependency on
> CONFIG_TMPFS && CONFIG_TMPFS_XATTR to CONFIG_SECURITY_FORK_BRUTE
> without messing with any fallbacks at all.
> What do you think?

Great. But I hope this patch will not be necessary for Brute LSM :)

Thanks,
John Wood