[PATCH 0/3] signal: HANDLER_EXIT should clear SIGNAL_UNKILLABLE

From: Kees Cook <keescook@chromium.org>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Kees Cook" <keescook@chromium.org>,
	"Robert Święcki" <robert@swiecki.net>,
	"Andy Lutomirski" <luto@amacapital.net>,
	"Will Drewry" <wad@chromium.org>,
	linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: [PATCH 0/3] signal: HANDLER_EXIT should clear SIGNAL_UNKILLABLE
Date: Wed,  9 Feb 2022 18:53:18 -0800	[thread overview]
Message-ID: <20220210025321.787113-1-keescook@chromium.org> (raw)

Hi,

This fixes the signal refactoring to actually kill unkillable processes
when receiving a fatal SIGSYS from seccomp. Thanks to Robert for the
report and Eric for the fix! I've also tweaked seccomp internal a bit to
fail more safely. This was a partial seccomp bypass, in the sense that
SECCOMP_RET_KILL_* didn't kill the process, but it didn't bypass other
aspects of the filters. (i.e. the syscall was still blocked, etc.)

I'll be sending this to Linus after a bit more testing...

Thanks,

-Kees

Kees Cook (3):
  signal: HANDLER_EXIT should clear SIGNAL_UNKILLABLE
  seccomp: Invalidate seccomp mode to catch death failures
  samples/seccomp: Adjust sample to also provide kill option

 kernel/seccomp.c          | 10 ++++++++++
 kernel/signal.c           |  5 +++--
 samples/seccomp/dropper.c |  9 +++++++--
 3 files changed, 20 insertions(+), 4 deletions(-)

-- 
2.30.2