Dear friends,
this patch series adds support for nested seccomp listeners. It allows container
runtimes and other sandboxing software to install seccomp listeners on top of
existing ones, which is useful for nested LXC containers and other similar use-cases.
Expecting potential discussions around this patch series, I'm going to present a talk
at LPC 2025 about the design and implementation details of this feature [1].
Git tree (based on for-next/seccomp):
v3: https://github.com/mihalicyn/linux/commits/seccomp.mult.listeners.v3
current: https://github.com/mihalicyn/linux/commits/seccomp.mult.listeners
Changelog for version 3:
- almost completely rewritten (no static array on the stack, no nesting limit)
- more testcases
Changelog for version 2:
- add some explanatory comments
- add RWB tags from Tycho Andersen (thanks, Tycho! ;) )
- CC-ed Aleksa as he might be interested in this stuff too
Links to previous versions:
v2: https://lore.kernel.org/all/20251202115200.110646-1-aleksandr.mikhalitsyn@canonical.com
tree: https://github.com/mihalicyn/linux/commits/seccomp.mult.listeners.v2
v1: https://lore.kernel.org/all/20251201122406.105045-1-aleksandr.mikhalitsyn@canonical.com
tree: https://github.com/mihalicyn/linux/commits/seccomp.mult.listeners.v1
Link: https://lpc.events/event/19/contributions/2241/ [1]
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: bpf@vger.kernel.org
Cc: Kees Cook <kees@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Will Drewry <wad@chromium.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Tycho Andersen <tycho@tycho.pizza>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Stéphane Graber <stgraber@stgraber.org>
Alexander Mikhalitsyn (7):
seccomp: remove unused argument from seccomp_do_user_notification
seccomp: use bitfields for boolean flags on seccomp_filter struct
seccomp: keep track of seccomp filters with closed listeners
seccomp: mark first listener in the tree
seccomp: handle multiple listeners case
seccomp: allow nested listeners
tools/testing/selftests/seccomp: test nested listeners
.../userspace-api/seccomp_filter.rst | 6 +
include/linux/seccomp.h | 3 +-
include/uapi/linux/seccomp.h | 13 +-
kernel/seccomp.c | 129 +++++++-
tools/include/uapi/linux/seccomp.h | 13 +-
tools/testing/selftests/seccomp/seccomp_bpf.c | 303 ++++++++++++++++++
6 files changed, 438 insertions(+), 29 deletions(-)
--
2.43.0