On Wed, Aug 7, 2013 at 11:05 AM, Oleg Nesterov <o...@redhat.com> wrote:
> If audit_filter_task() nacks the new thread it makes sense
> to clear TIF_SYSCALL_AUDIT which can be copied from parent
> by dup_task_struct().
>
> A wrong TIF_SYSCALL_AUDIT is not really bad, but it triggers
> the "slow" audit paths in entry.S.
>
> Signed-off-by: Oleg Nesterov <o...@redhat.com>
> ---
> kernel/auditsc.c | 4 +++-
> 1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index 9845cb3..95293ab 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -943,8 +943,10 @@ int audit_alloc(struct task_struct *tsk)
> return 0; /* Return if not auditing. */
>
> state = audit_filter_task(tsk, &key);
> - if (state == AUDIT_DISABLED)
> + if (state == AUDIT_DISABLED) {
> + clear_tsk_thread_flag(tsk, TIF_SYSCALL_AUDIT);
> return 0;
> + }
>
> if (!(context = audit_alloc_context(state))) {
> kfree(key);
> --
> 1.5.5.1
>
>
Interestingly, I see no other callers of "clear_tsk_thread_flag(tsk,
TIF_SYSCALL_AUDIT)" :)
This patch seems right, since TIF_SYSCALL_AUDIT is set only when
audit_filter_task != AUDIT_DISABLED. Though maybe this should be
explicitly handled in dup_task_struct()?
-Kees
--
Kees Cook
Chrome OS Security
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