Hey everyone,
This is the patchset coming out of the KSummit session Kees and I gave in Lisbon last week (cf. [3] which also contains slides with more details on related things such as deep argument inspection). The simple idea is to extend the seccomp notifier to allow for the continuation of a syscall. The rationale for this can be found in the commit message to [1]. For the curious there is more detail in [2]. This patchset would unblock supervising an extended set of syscalls such as mount() where a privileged process is supervising the syscalls of a lesser privileged process and emulates the syscall for the latter in userspace. For more comments on security see [1].
Kees, if you prefer a pr the series can be pulled from: git@gitolite.kernel.org:pub/scm/linux/kernel/git/brauner/linux tags/seccomp-notify-syscall-continue-v5.5
For anyone who wants to play with this it's sitting in: https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git/log/?h=sec...
/* v1 */ - Kees Cook keescook@chromium.org: - dropped patch because it is already present in linux-next [PATCH 2/4] seccomp: add two missing ptrace ifdefines Link: https://lore.kernel.org/r/20190918084833.9369-3-christian.brauner@ubuntu.com
/* v0 */ Link: https://lore.kernel.org/r/20190918084833.9369-1-christian.brauner@ubuntu.com
Thanks! Christian
/* References */ [1]: [PATCH 1/3] seccomp: add SECCOMP_USER_NOTIF_FLAG_CONTINUE [2]: https://lore.kernel.org/r/20190719093538.dhyopljyr5ns33qx@brauner.io [3]: https://linuxplumbersconf.org/event/4/contributions/560
Christian Brauner (3): seccomp: add SECCOMP_USER_NOTIF_FLAG_CONTINUE seccomp: avoid overflow in implicit constant conversion seccomp: test SECCOMP_USER_NOTIF_FLAG_CONTINUE
include/uapi/linux/seccomp.h | 20 ++++ kernel/seccomp.c | 28 ++++- tools/testing/selftests/seccomp/seccomp_bpf.c | 105 +++++++++++++++++- 3 files changed, 146 insertions(+), 7 deletions(-)