Messages in this thread | | | Date | Tue, 3 Oct 2023 11:01:52 -0700 | From | Kees Cook <> | Subject | Re: [RFC PATCH 0/2] seccomp: Split set filter into two steps |
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On Tue, Oct 03, 2023 at 08:38:34AM +0000, Hengqi Chen wrote: > 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.
Interesting! I like this idea, thanks for writing it up.
Two design notes:
- Can you reuse/refactor seccomp_prepare_filter() instead of duplicating the logic into two new functions?
- Is there a way to make sure the BPF program coming from the fd is one that was built via SECCOMP_LOAD_FILTER? (I want to make sure we can never confuse a non-seccomp program into getting loaded into seccomp.)
-Kees
-- Kees Cook
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