1 files changed, 41 insertions, 1 deletions

diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index a5bab190a297..761af8ce4015 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -20,6 +20,7 @@
 #include <linux/parser.h>
 #include <linux/magic.h>
 #include <linux/slab.h>
+#include <linux/security.h>
 
 #define TRACEFS_DEFAULT_MODE	0700
 
@@ -27,6 +28,25 @@ static struct vfsmount *tracefs_mount;
 static int tracefs_mount_count;
 static bool tracefs_registered;
 
+static int default_open_file(struct inode *inode, struct file *filp)
+{
+	struct dentry *dentry = filp->f_path.dentry;
+	struct file_operations *real_fops;
+	int ret;
+
+	if (!dentry)
+		return -EINVAL;
+
+	ret = security_locked_down(LOCKDOWN_TRACEFS);
+	if (ret)
+		return ret;
+
+	real_fops = dentry->d_fsdata;
+	if (!real_fops->open)
+		return 0;
+	return real_fops->open(inode, filp);
+}
+
 static ssize_t default_read_file(struct file *file, char __user *buf,
 				 size_t count, loff_t *ppos)
 {
@@ -221,6 +241,12 @@ static int tracefs_apply_options(struct super_block *sb)
 	return 0;
 }
 
+static void tracefs_destroy_inode(struct inode *inode)
+{
+	if (S_ISREG(inode->i_mode))
+		kfree(inode->i_fop);
+}
+
 static int tracefs_remount(struct super_block *sb, int *flags, char *data)
 {
 	int err;
@@ -257,6 +283,7 @@ static int tracefs_show_options(struct seq_file *m, struct dentry *root)
 static const struct super_operations tracefs_super_operations = {
 	.statfs		= simple_statfs,
 	.remount_fs	= tracefs_remount,
+	.destroy_inode  = tracefs_destroy_inode,
 	.show_options	= tracefs_show_options,
 };
 
@@ -387,6 +414,7 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode,
 				   struct dentry *parent, void *data,
 				   const struct file_operations *fops)
 {
+	struct file_operations *proxy_fops;
 	struct dentry *dentry;
 	struct inode *inode;
 
@@ -402,8 +430,20 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode,
 	if (unlikely(!inode))
 		return failed_creating(dentry);
 
+	proxy_fops = kzalloc(sizeof(struct file_operations), GFP_KERNEL);
+	if (unlikely(!proxy_fops)) {
+		iput(inode);
+		return failed_creating(dentry);
+	}
+
+	if (!fops)
+		fops = &tracefs_file_operations;
+
+	dentry->d_fsdata = (void *)fops;
+	memcpy(proxy_fops, fops, sizeof(*proxy_fops));
+	proxy_fops->open = default_open_file;
 	inode->i_mode = mode;
-	inode->i_fop = fops ? fops : &tracefs_file_operations;
+	inode->i_fop = proxy_fops;
 	inode->i_private = data;
 	d_instantiate(dentry, inode);
 	fsnotify_create(dentry->d_parent->d_inode, dentry);