[PATCH 1/2] file capabilities: don't do file caps if MNT_NOSUID

["Serge E. Hallyn" <serue@us.ibm.com>]

From: Serge E. Hallyn <serue@us.ibm.com>
Subject: [PATCH 1/2] file capabilities: don't do file caps if MNT_NOSUID

A file system mounted NOSUID is likely a removable filesystem.
Allowing file capabilities from such an fs is an easy attack
vector, so don't honor file capabilities for a NOSUID
filesystem.

Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
---
 security/commoncap.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/security/commoncap.c b/security/commoncap.c
index ce91d9f..fde9695 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -23,6 +23,7 @@ #include <linux/netlink.h>
 #include <linux/ptrace.h>
 #include <linux/xattr.h>
 #include <linux/hugetlb.h>
+#include <linux/mount.h>
 
 int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
 {
@@ -152,6 +153,9 @@ static int set_file_caps(struct linux_bi
 	struct inode *inode;
 	int err;
 
+	if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)
+		return 0;
+
 	dentry = dget(bprm->file->f_dentry);
 	inode = dentry->d_inode;
 	if (!inode->i_op || !inode->i_op->getxattr) {
-- 
1.4.1