lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Thu, 21 Feb 2019 16:22:34 -0800 From: Andy Lutomirski <luto@...nel.org> To: Kees Cook <keescook@...omium.org> Cc: Alexei Starovoitov <alexei.starovoitov@...il.com>, Jann Horn <jannh@...gle.com>, Daniel Borkmann <daniel@...earbox.net>, Alexei Starovoitov <ast@...nel.org>, Network Development <netdev@...r.kernel.org> Subject: Re: [PATCH bpf-next v2] bpf, seccomp: fix false positive preemption splat for cbpf->ebpf progs On Thu, Feb 21, 2019 at 2:14 PM Kees Cook <keescook@...omium.org> wrote: > > On Thu, Feb 21, 2019 at 12:36 PM Alexei Starovoitov > <alexei.starovoitov@...il.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.) > I consider the potential for much improved performance to be a maybe-good-enough argument. The down side is that there are programs that load cBPF seccomp filters from inside a sandbox, and being able to load eBPF from inside a sandbox is potentially undesirable.
Powered by blists - more mailing lists