Re: [PATCH 4/6] seccomp: add a way to access filters via bpf fds

Alexei Starovoitov
2015-09-04T20:29:57Z

On Fri, Sep 04, 2015 at 01:26:42PM -0700, Kees Cook wrote:
> On Fri, Sep 4, 2015 at 9:04 AM, Tycho Andersen
> <tycho.andersen@canonical.com> wrote:
> > This patch adds a way for a process that is "real root" to access the
> > seccomp filters of another process. The process first does a
> > PTRACE_SECCOMP_GET_FILTER_FD to get an fd with that process' seccomp filter
> > attached, and then iterates on this with PTRACE_SECCOMP_NEXT_FILTER using
> > bpf(BPF_PROG_DUMP) to dump the actual program at each step.
>
> Why is this a new ptrace interface instead of a new seccomp interface?
> I would expect this to only be valid for "current", otherwise we could
> run into races as the ptracee adds filters. i.e. it is not safe to
> examine seccomp filters from tasks other than current.

same question.
I thought we discussed to add a command to seccomp() syscall for that?