From: Kees Cook <keescook@chromium.org>
Date: Mon, 25 Feb 2013 21:32:25 +0000 (+0000)
Subject: proc connector: reject unprivileged listener bumps
X-Git-Tag: v3.2.41~70
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=7c4bf08d3fa22613b628fc967953f581564a13ad;p=thirdparty%2Fkernel%2Fstable.git

proc connector: reject unprivileged listener bumps

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>
---

diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c
index 77e1e6cd66ce0..46bbf4317dae9 100644
--- a/drivers/connector/cn_proc.c
+++ b/drivers/connector/cn_proc.c
@@ -303,6 +303,12 @@ static void cn_proc_mcast_ctl(struct cn_msg *msg,
 	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_msg *msg,
 		err = EINVAL;
 		break;
 	}
+
+out:
 	cn_proc_ack(err, msg->seq, msg->ack);
 }