From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?q?J=C3=BCrg=20Billeter?= Subject: [PATCH v2 0/1] Add prctl to kill descendants on exit Date: Fri, 30 Nov 2018 08:00:03 +0000 Message-ID: <20181130080004.23635-1-j@bitron.ch> References: <20181127225408.7553-2-j@bitron.ch> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20181127225408.7553-2-j@bitron.ch> Sender: linux-kernel-owner@vger.kernel.org To: Andrew Morton Cc: Oleg Nesterov , Thomas Gleixner , Eric Biederman , Kees Cook , Andy Lutomirski , linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, =?UTF-8?q?J=C3=BCrg=20Billeter?= List-Id: linux-api@vger.kernel.org This patch adds a new prctl to kill all descendant processes on exit. See commit message for details of the prctl. This is a replacement of PR_SET_PDEATHSIG_PROC I proposed last year [1]. In the following discussion, Oleg suggested this approach. The motivation for this is to provide a lightweight mechanism to prevent stray processes. There is also a related Bugzilla entry [2]. PID namespaces can also be used to prevent stray processes, of course. However, they are not quite as lightweight as they typically also require a new mount namespace to be able to mount a new /proc. And they require CAP_SYS_ADMIN. User namespaces can help to gain CAP_SYS_ADMIN, however, that further increases the overhead and the other effects of the user namespace may not be desired. PID 1 in PID namespaces also exhibits non-standard signal behavior (SIGNAL_UNKILLABLE) [3]. Changes in v2: - Use bool instead of bitfield to avoid race with PR_SET_CHILD_SUBREAPER [1] https://lkml.kernel.org/lkml/20170929123058.48924-1-j@bitron.ch/ [2] https://bugzilla.kernel.org/show_bug.cgi?id=43300 [3] https://lkml.kernel.org/lkml/20180803144021.56920-2-j@bitron.ch/ Jürg Billeter (1): prctl: add PR_{GET,SET}_KILL_DESCENDANTS_ON_EXIT fs/exec.c | 6 ++++++ include/linux/sched/signal.h | 3 +++ include/uapi/linux/prctl.h | 4 ++++ kernel/exit.c | 12 ++++++++++++ kernel/sys.c | 11 +++++++++++ security/apparmor/lsm.c | 1 + security/selinux/hooks.c | 3 +++ 7 files changed, 40 insertions(+) -- 2.19.2