[PATCH 0/4] seccomp: Make seccomp filter reusable

[Hengqi Chen]

This patchset introduces two new operations which essentially
splits the SECCOMP_SET_MODE_FILTER process into two steps:
SECCOMP_LOAD_FILTER and SECCOMP_ATTACH_FILTER.

The SECCOMP_LOAD_FILTER loads the filter and returns a fd
which can be pinned to bpffs. This extends the lifetime of the
filter and thus can be reused by different processes.
With this new operation, we can eliminate a hot path of JITing
BPF program (the filter) where we apply the same seccomp filter
to thousands of micro VMs on a bare metal instance.

The SECCOMP_ATTACH_FILTER is used to attach a loaded filter.
The filter is represented by a fd which is either returned
from SECCOMP_LOAD_FILTER or obtained from bpffs using bpf syscall.

Changes from RFC ([0]):
  - Addressed comments from Kees
  - Reuse filter copy/create code (patch 1)
  - Add a selftest (patch 4)

  [0]: https://lore.kernel.org/all/20231003083836.100706-1-hengqi.chen@xxxxxxxxx/

Hengqi Chen (4):
  seccomp: Refactor filter copy/create for reuse
  seccomp, bpf: Introduce SECCOMP_LOAD_FILTER operation
  seccomp: Introduce SECCOMP_ATTACH_FILTER operation
  selftests/seccomp: Test SECCOMP_LOAD_FILTER and SECCOMP_ATTACH_FILTER

 include/uapi/linux/bpf.h                      |   1 +
 include/uapi/linux/seccomp.h                  |   2 +
 kernel/seccomp.c                              | 184 +++++++++++++++---
 tools/testing/selftests/seccomp/seccomp_bpf.c |  20 ++
 4 files changed, 180 insertions(+), 27 deletions(-)

-- 
2.34.1