Messages in this thread | | | Date | Thu, 25 Oct 2018 17:17:13 -0700 | From | Alexei Starovoitov <> | Subject | Re: [PATCH bpf] bpf: add bpf_jit_limit knob to restrict unpriv allocations |
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On Tue, Oct 23, 2018 at 01:11:04AM +0200, Daniel Borkmann wrote: > Rick reported that the BPF JIT could potentially fill the entire module > space with BPF programs from unprivileged users which would prevent later > attempts to load normal kernel modules or privileged BPF programs, for > example. If JIT was enabled but unsuccessful to generate the image, then > before commit 290af86629b2 ("bpf: introduce BPF_JIT_ALWAYS_ON config") > we would always fall back to the BPF interpreter. Nowadays in the case > where the CONFIG_BPF_JIT_ALWAYS_ON could be set, then the load will abort > with a failure since the BPF interpreter was compiled out. > > Add a global limit and enforce it for unprivileged users such that in case > of BPF interpreter compiled out we fail once the limit has been reached > or we fall back to BPF interpreter earlier w/o using module mem if latter > was compiled in. In a next step, fair share among unprivileged users can > be resolved in particular for the case where we would fail hard once limit > is reached. > > Fixes: 290af86629b2 ("bpf: introduce BPF_JIT_ALWAYS_ON config") > Fixes: 0a14842f5a3c ("net: filter: Just In Time compiler for x86-64") > Co-Developed-by: Rick Edgecombe <rick.p.edgecombe@intel.com> > Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> > Acked-by: Alexei Starovoitov <ast@kernel.org> > Cc: Eric Dumazet <eric.dumazet@gmail.com> > Cc: Jann Horn <jannh@google.com> > Cc: Kees Cook <keescook@chromium.org> > Cc: LKML <linux-kernel@vger.kernel.org> > --- > Hi Rick, I've reworked the original patch into something much simpler > which is only focussing on the actual main issue we want to resolve right > now as a first step to make some forward progress, that is, limiting usage > on the JIT for unprivileged users. Tested the below on x86 and arm64. > (Trimmed down massive Cc list as well a bit and Cc'ed people related to > commits referenced and netdev where BPF patches are usually discussed.) > Thanks a lot!
Applied to bpf tree. Thanks Daniel.
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