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. */
+ 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_msg *msg,
err = EINVAL;
break;
}
+
+out:
cn_proc_ack(err, msg->seq, msg->ack);
}
--
1.7.9.5
--
Kees Cook
Chrome OS Security
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