On Mon, Feb 25, 2013 at 11:32:25PM -0800, Kees Cook wrote:
> While PROC_CN_MCAST_LISTEN/IGNORE is entirely advisory, it was possible
> for an unprivileged user to turn off notifications for all listeners by
> sending PROC_CN_MCAST_IGNORE. Instead, require the same privileges as
> required for a multicast bind.
>
> Signed-off-by: Kees Cook <keesc...@chromium.org>
> Cc: Evgeniy Polyakov <z...@ioremap.net>
> Cc: Matt Helsley <matth...@us.ibm.com>
> Cc: sta...@vger.kernel.org
> ---
> drivers/connector/cn_proc.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c
> index fce2000..1110478 100644
> --- a/drivers/connector/cn_proc.c
> +++ b/drivers/connector/cn_proc.c
> @@ -313,6 +313,12 @@ static void cn_proc_mcast_ctl(struct cn_msg *msg,
> (task_active_pid_ns(current) != &init_pid_ns))
> return;
>
> + /* Can only change if privileged. */
I think this comment doesn't tell us anything above and beyond the
what capability check already tells us. I think you could improve it
by noting that since the connector is multicast and not namespace-safe
it's not yet appropriate to use ns_capable() here.
Acked-by: Matt Helsley <matth...@us.ibm.com>
> + if (!capable(CAP_NET_ADMIN)) {
> + err = EPERM;
> + goto out;
> + }
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