linux-kernel - Re: [PATCH 05/10] lkdtm: disable set_fs-based tests for !CONFIG_SET

lists.openwall.net		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 linux-cve-announce 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]

Message-ID: <202009011156.0F49882@keescook>
Date:   Tue, 1 Sep 2020 11:57:37 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Christoph Hellwig <hch@....de>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Michael Ellerman <mpe@...erman.id.au>,
        the arch/x86 maintainers <x86@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH 05/10] lkdtm: disable set_fs-based tests for
 !CONFIG_SET_FS

On Sat, Aug 29, 2020 at 11:24:06AM +0200, Christoph Hellwig wrote:
> On Thu, Aug 27, 2020 at 11:06:28AM -0700, Linus Torvalds wrote:
> > On Thu, Aug 27, 2020 at 8:00 AM Christoph Hellwig <hch@....de> wrote:
> > >
> > > Once we can't manipulate the address limit, we also can't test what
> > > happens when the manipulation is abused.
> > 
> > Just remove these tests entirely.
> > 
> > Once set_fs() doesn't exist on x86, the tests no longer make any sense
> > what-so-ever, because test coverage will be basically zero.
> > 
> > So don't make the code uglier just to maintain a fiction that
> > something is tested when it isn't really.
> 
> Sure fine with me unless Kees screams.

To clarify: if any of x86, arm64, arm, powerpc, riscv, and s390 are
using set_fs(), I want to keep this test. "ugly" is fine in lkdtm. :)

-- 
Kees Cook