[ 12/82] proc connector: reject unprivileged listener bumps

Ben Hutchings
2013-03-18T04:31:04Z

From: Kees Cook <keescook@chromium.org>

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 <keescook@chromium.org>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Matt Helsley <matthltc@us.ibm.com>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Acked-by: Matt Helsley <matthltc@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/connector/cn_proc.c | 8 ++++++++
1 file changed, 8 insertions(+)

--- a/drivers/connector/cn_proc.c
+++ b/drivers/connector/cn_proc.c
@@ -303,6 +303,12 @@ static void cn_proc_mcast_ctl(struct cn_
if (msg->len != sizeof(*mc_op))
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:
@@ -315,6 +321,8 @@ static void cn_proc_mcast_ctl(struct cn_
err = EINVAL;
break;
}
+
+out:
cn_proc_ack(err, msg->seq, msg->ack);
}