3.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Kees Cook <[email protected]>

commit e70ab977991964a5a7ad1182799451d067e62669 upstream.

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 <[email protected]>
Cc: Evgeniy Polyakov <[email protected]>
Cc: Matt Helsley <[email protected]>
Acked-by: Evgeniy Polyakov <[email protected]>
Acked-by: Matt Helsley <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 drivers/connector/cn_proc.c |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/drivers/connector/cn_proc.c
+++ b/drivers/connector/cn_proc.c
@@ -313,6 +313,12 @@ static void cn_proc_mcast_ctl(struct cn_
            (task_active_pid_ns(current) != &init_pid_ns))
                return;
 
+       /* Can only change if privileged. */
+       if (!capable(CAP_NET_ADMIN)) {
+               err = EPERM;
+               goto out;
+       }
+
        mc_op = (enum proc_cn_mcast_op *)msg->data;
        switch (*mc_op) {
        case PROC_CN_MCAST_LISTEN:
@@ -325,6 +331,8 @@ static void cn_proc_mcast_ctl(struct cn_
                err = EINVAL;
                break;
        }
+
+out:
        cn_proc_ack(err, msg->seq, msg->ack);
 }
 


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