Re: [PATCH] audit: clear thread flag for new children

[Steve Grubb <sgrubb@redhat.com>]

On Monday 29 October 2007 01:20:58 pm Tony Jones wrote:
> > The problem is that removing that flag makes the children unauditable in
> > the future. The only place that flag gets set is during fork.
>
> I don't see this.

If the child does not have the TIF_SYSCALL_AUDIT flag, it never goes into 
audit_syscall_entry. It becomes unauditable.


> The case that would be undesirable would be for a task to have an audit
> context but to not have the thread flag enabled.

That would just be a small allocation of memory that will be returned when the 
process exits. From an auditing PoV, something that is undesirable is the 
inability to audit a process that you want to audit.


> > Unless I'm missing something, to make all children auditable again would
> > mean stopping all processes and or'ing that flag into all thread info
> > areas.
>
> I think you are.  Or maybe the code was different two years ago so that the
> above made sense.  
>
> In the above scenario, audit is disabled, a new child is forked, we bail
> early so there is no audit context (and now there is no flag in the thread
> area).   Currently there is no way this task is ever going to be audited as
> there is no audit context. 

So when audit is re-enabled, how do you make that task auditable?


> If this task forks a new child, at this point the value of audit enabled
> will determine if there should be a context allocated and it will allocate
> the TIF flag also.

In the new child, but not the parent.


> I don't see your stopping all processes scenario. 

That is so you can walk the process table and "or" the bit in unconditionally. 
All processes need to be auditable or you've got a security hole.

-Steve