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@xxxxxxxxx/
[2] https://bugzilla.kernel.org/show_bug.cgi?id=43300
[3] https://lkml.kernel.org/lkml/20180803144021.56920-2-j@xxxxxxxxx/
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
