[PATCH v3 3/3] binder: use euid from cred instead of using task

[Todd Kjos]

On Wed, Oct 6, 2021 at 12:46 PM Todd Kjos <tkjos at google.com> wrote:
>
> Set a transaction's sender_euid from the the 'struct cred'
> saved at binder_open() instead of looking up the euid
> from the binder proc's 'struct task'. This ensures
> the euid is associated with the security context that
> of the task that opened binder.
>
> Fixes: 457b9a6f09f0 ("Staging: android: add binder driver")
> Signed-off-by: Todd Kjos <tkjos at google.com>
> Stephen Smalley <stephen.smalley.work at gmail.com>

This should have been "Suggested-by: Stephen Smalley
<stephen.smalley.work at gmail.com>"

> Cc: stable at vger.kernel.org # 4.4+
> ---
> v3: added this patch to series
>
>  drivers/android/binder.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/android/binder.c b/drivers/android/binder.c
> index 989afd0804ca..26382e982c5e 100644
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -2711,7 +2711,7 @@ static void binder_transaction(struct binder_proc *proc,
>                 t->from = thread;
>         else
>                 t->from = NULL;
> -       t->sender_euid = task_euid(proc->tsk);
> +       t->sender_euid = proc->cred->euid;
>         t->to_proc = target_proc;
>         t->to_thread = target_thread;
>         t->code = tr->code;
> --
> 2.33.0.800.g4c38ced690-goog
>