linux-hardening - Re: [PATCH v1 0/8] Run KUnit tests late and handle faults

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Message-ID: <20240301.gaiWei9eng4u@digikod.net>
Date: Fri, 1 Mar 2024 20:19:50 +0100
From: Mickaël Salaün <mic@...ikod.net>
To: David Gow <davidgow@...gle.com>
Cc: Brendan Higgins <brendanhiggins@...gle.com>, 
	Kees Cook <keescook@...omium.org>, Rae Moar <rmoar@...gle.com>, 
	Shuah Khan <skhan@...uxfoundation.org>, Alan Maguire <alan.maguire@...cle.com>, 
	Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, 
	"H . Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>, 
	James Morris <jamorris@...ux.microsoft.com>, Luis Chamberlain <mcgrof@...nel.org>, 
	"Madhavan T . Venkataraman" <madvenka@...ux.microsoft.com>, Marco Pagani <marpagan@...hat.com>, 
	Paolo Bonzini <pbonzini@...hat.com>, Sean Christopherson <seanjc@...gle.com>, 
	Stephen Boyd <sboyd@...nel.org>, Thara Gopinath <tgopinath@...rosoft.com>, 
	Thomas Gleixner <tglx@...utronix.de>, Vitaly Kuznetsov <vkuznets@...hat.com>, 
	Wanpeng Li <wanpengli@...cent.com>, Zahra Tarkhani <ztarkhani@...rosoft.com>, kvm@...r.kernel.org, 
	linux-hardening@...r.kernel.org, linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-security-module@...r.kernel.org, linux-um@...ts.infradead.org, x86@...nel.org
Subject: Re: [PATCH v1 0/8] Run KUnit tests late and handle faults

On Fri, Mar 01, 2024 at 03:15:08PM +0800, David Gow wrote:
> On Fri, 1 Mar 2024 at 01:04, Mickaël Salaün <mic@...ikod.net> wrote:
> >
> > Hi,
> >
> 
> Thanks very much. I think there's a lot going on in this series, and
> it'd probably be easier to address if it were broken up a bit more.
> 
> To take things one at a time:
> 
> > This patch series moves KUnit test execution at the very end of kernel
> > initialization, just before launching the init process.  This opens the
> > way to test any kernel code in its normal state (i.e. fully
> > initialized).
> 
> I like the general idea here, but there are a few things to keep in mind:
> - We can already do this with tests built as modules.
> - We have explicit support for testing __init code, so if we want to
> keep that (and I think we do), we'll need to make sure that there
> remains a way to run tests before __init.
> - Behaviour changes here will need to be documented and tested well
> across all tests and architectures, so it's not something I'd want to
> land quickly.
> - The requirement to have a root filesystem set up is another thing
> we'll want to handle carefully.
> - As-is, the patch seems to break arm64.

Fair, I'll remove this patch from the next series.

> 
> >
> > This patch series also teaches KUnit to handle kthread faults as errors,
> > and it brings a few related fixes and improvements.
> 
> These seem very good overall. I want to look at the last location
> stuff in a bit more detail, but otherwise this is okay.

Thanks!

> 
> Personally, I'd like to see this split out into a separate series,
> partly because I don't want to delay it while we sort the other parts
> of this series out, and partly because I have some other changes to
> the thread context stuff I think we need to make.

I'll do that today.

> 
> >
> > New tests check NULL pointer dereference and read-only memory, which
> > wasn't possible before.
> 
> These look interesting, but I don't like that they are listed as x86-specific.

I was reluctant to make it more broadly available because I only tested
on x86...

> 
> >
> > This is useful to test current kernel self-protection mechanisms or
> > future ones such as Heki: https://github.com/heki-linux
> >
> > Regards,
> 
> Thanks again. I'll do a more detailed review of the individual patches
> next week, but I'm excited to see this overall.

Good, you'll review the v2 then.

> 
> Cheers,
> -- David
> 
> 
> >
> > Mickaël Salaün (8):
> >   kunit: Run tests when the kernel is fully setup
> >   kunit: Handle thread creation error
> >   kunit: Fix kthread reference
> >   kunit: Fix timeout message
> >   kunit: Handle test faults
> >   kunit: Fix KUNIT_SUCCESS() calls in iov_iter tests
> >   kunit: Print last test location on fault
> >   kunit: Add tests for faults
> >
> >  include/kunit/test.h                |  24 +++++-
> >  include/kunit/try-catch.h           |   3 -
> >  init/main.c                         |   4 +-
> >  lib/bitfield_kunit.c                |   8 +-
> >  lib/checksum_kunit.c                |   2 +-
> >  lib/kunit/executor.c                |  81 ++++++++++++++------
> >  lib/kunit/kunit-example-test.c      |   6 +-
> >  lib/kunit/kunit-test.c              | 115 +++++++++++++++++++++++++++-
> >  lib/kunit/try-catch.c               |  33 +++++---
> >  lib/kunit_iov_iter.c                |  70 ++++++++---------
> >  tools/testing/kunit/kunit_kernel.py |   6 +-
> >  11 files changed, 261 insertions(+), 91 deletions(-)
> >
> >
> > base-commit: d206a76d7d2726f3b096037f2079ce0bd3ba329b
> > --
> > 2.44.0
> >