[PATCH v1 0/3] seccomp: continue syscall from notifier

[Christian Brauner]

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@xxxxxxxxxxxxxxxxxxx: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=seccomp_syscall_continue

/* v1 */
- Kees Cook <keescook@xxxxxxxxxxxx>:
  - 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@xxxxxxxxxx

/* v0 */
Link: https://lore.kernel.org/r/20190918084833.9369-1-christian.brauner@xxxxxxxxxx

Thanks!
Christian

/* References */
[1]: [PATCH 1/3] seccomp: add SECCOMP_USER_NOTIF_FLAG_CONTINUE
[2]: https://lore.kernel.org/r/20190719093538.dhyopljyr5ns33qx@xxxxxxxxxx
[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(-)

-- 
2.23.0