[PATCH] sysctl: hide the sysctl proc inodes from selinux

Since the security checks are applied on each read and write of a sysctl file,
just like they are applied when calling sys_sysctl, they are redundant on the
standard VFS constructs.  Since it is difficult to compute the security labels
on the standard VFS constructs we just mark the sysctl inodes in proc private
so selinux won't even bother with them.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fs/proc/proc_sysctl.c

@@ -47,6 +47,7 @@ static struct inode *proc_sys_make_inode(struct inode *dir, struct ctl_table *ta
 	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 	inode->i_op = &proc_sys_inode_operations;
 	inode->i_fop = &proc_sys_file_operations;
+	inode->i_flags |= S_PRIVATE; /* tell selinux to ignore this inode */
 	proc_sys_refresh_inode(inode, table);
 out:
 	return inode;