Re: [PATCH] audit: speedup for syscalls when auditing is disabled
On Tue, 2010-08-24 at 12:16 +1000, Anton Blanchard wrote:
Hi Eric,
> I don't think this works at all. I don't see how syscall audit'ing can
> work. What if I have nothing in the AUDIT_FILTER_TASK list but I want
> to audit all 'open(2)' syscalls? This patch is going to leave the task
> in the DISABLED state and we won't ever be able to match on the syscall
> rules.
That's a good point. What if we went through and created an audit context
for each thread at the point where we add a rule to the audit subsystem?
That would make the common case where no one touches audit go fast. It's
only once you add a rule that you get the syscall entry/exit overhead of
audit.
Anton
It might be viable but I certainly couldn't say. I'm a bit scared of
allocating and attaching a struct audit_context to a running task as we
have no idea if that task is about to exit a syscall with an unfilled
out audit_context struct nor do I personally off the top of my head know
the task flag setting rules (especially when you want to set other
people's flags)
Maybe another approach would be to move audit_alloc() into the syscall
entry path rather than only at fork().
I think the best solution is going to be some better way of
setting/clearing TIF_SYSCALL_AUDIT. (notice the thing is never cleared,
ever, today)
-Eric