On Thu, Feb 21, 2019 at 12:36 PM Alexei Starovoitov <alexei.starovoi...@gmail.com> wrote: > I also would like to touch on your comment: > "A lot of changes will be needed for seccomp ebpf" > There were two attempts to add it in the past and the patches were > small and straightforward.
Yeah, agreed: doing it is technically easy. My concerns have mainly revolved around avoiding increased complexity and attack surface. There have been, for example, a lot of verifier bugs that were not reachable through seccomp's BPF usage, given it enforcing only using a subset of cBPF. i.e. seccomp filters couldn't be used as Spectre gadgets, etc. > If I recall correctly both times you nacked them because performance gains > and ease of use arguments were not convincing enough, right? Right. There wasn't, in my opinion enough of a performance benefit vs just having efficient BPF to start with. > Are you still not convinced ? For now, yeah. I'm sure there will be some future time when a use-case appears where gaining some special eBPF hook/feature will outweigh the increased attack surface. I haven't seen it yet, but I'm not crazy enough to think it'll never happen. (In fact, recently I even had Tycho see if he could implement the recent seccomp user notification stuff via eBPF.) -- Kees Cook
