lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Sun, 4 Jul 2021 16:01:08 +0200
From:   John Wood <>
To:     Alexander Lobakin <>
Cc:     John Wood <>, Kees Cook <>,
        Jann Horn <>, Jonathan Corbet <>,
        James Morris <>,
        "Serge E. Hallyn" <>,
        Shuah Khan <>,
        Thomas Gleixner <>,
        Ingo Molnar <>, Borislav Petkov <>,, "H. Peter Anvin" <>,
        Arnd Bergmann <>, Andi Kleen <>,,
        Greg Kroah-Hartman <>,
        Randy Dunlap <>,
        Andrew Morton <>,,,,,,,
Subject: Re: [PATCH v8 3/8] security/brute: Detect a brute force attack

On Sat, Jul 03, 2021 at 12:59:28PM +0200, John Wood wrote:
> 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 have been coding and testing a bit my ideas but:

Trying to track the applications faults info using kernel memory ends up
in an easy to abuse system (denied of service due to large amount of memory
in use) :(

So, I continue with the v8 idea: xattr to track application crashes info.

> > 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
> > without messing with any fallbacks at all.
> > What do you think?
> Great. But I hope this patch will not be necessary for Brute LSM :)

My words are no longer valid ;)

John Wood

Powered by blists - more mailing lists