On Sat, Oct 03, 2015 at 12:57:49AM +0200, Daniel Borkmann wrote:

On 10/03/2015 12:44 AM, Tycho Andersen wrote:

quoted

On Fri, Oct 02, 2015 at 02:10:24PM -0700, Kees Cook wrote:

...

quoted

Ok, how about,

struct sock_filter insns[BPF_MAXINSNS];
insn_cnt = ptrace(PTRACE_SECCOMP_GET_FILTER, pid, insns, i);

Would also be good that when the storage buffer (insns) is NULL,
it just returns you the number of sock_filter insns (or 0 when
nothing attached).

That would be consistent with classic socket filters (see
sk_get_filter()), and user space could allocate a specific
size instead of always passing in max insns.

Yep, the current set does this with SECCOMP_FD_DUMP and I agree that
it's nice behavior, so I'll plan on preserving it.

Thanks,

Tycho