On 02/27, Kees Cook wrote:
>
> On Mon, Feb 27, 2012 at 9:11 AM, Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
> > On 02/24, Will Drewry wrote:
> >>
> >> static u32 seccomp_run_filters(int syscall)
> >> {
> >> struct seccomp_filter *f;
> >> - u32 ret = SECCOMP_RET_KILL;
> >> static const struct bpf_load_fn fns = {
> >> bpf_load,
> >> sizeof(struct seccomp_data),
> >> };
> >> + u32 ret = SECCOMP_RET_ALLOW;
> >> const void *sc_ptr = (const void *)(uintptr_t)syscall;
> >>
> >> + /* Ensure unexpected behavior doesn't result in failing open. */
> >> + if (unlikely(current->seccomp.filter == NULL))
> >> + ret = SECCOMP_RET_KILL;
> >
> > Is "seccomp.filter == NULL" really possible?
>
> It should not be, but I'm much more comfortable with this failing
> closed. I think it's important to be as defensive as possible with
> this code given its intended use.
Can't resists... Sorry, I know I am troll but personally I think
in this case the most defensive code is BUG_ON(->filter == NULL)
or at least WARN_ON().
Nevermind, I won't pretend I really understand the intended use,
please ignore.
Oleg.
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