eCryptfs: Handle ioctl calls with unlocked and compat functions

Lower filesystems that only implemented unlocked_ioctl weren't being
passed ioctl calls because eCryptfs only checked for
lower_file->f_op->ioctl and returned -ENOTTY if it was NULL.

eCryptfs shouldn't implement ioctl(), since it doesn't require the BKL.
This patch introduces ecryptfs_unlocked_ioctl() and
ecryptfs_compat_ioctl(), which passes the calls on to the lower file
system.

https://bugs.launchpad.net/ecryptfs/+bug/469664

Reported-by: James Dupin <james.dupin@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>

fs/ecryptfs/file.c

@@ -292,12 +292,40 @@ static int ecryptfs_fasync(int fd, struct file *file, int flag)
 	return rc;
 }
 
-static int ecryptfs_ioctl(struct inode *inode, struct file *file,
-			  unsigned int cmd, unsigned long arg);
+static long
+ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct file *lower_file = NULL;
+	long rc = -ENOTTY;
+
+	if (ecryptfs_file_to_private(file))
+		lower_file = ecryptfs_file_to_lower(file);
+	if (lower_file && lower_file->f_op && lower_file->f_op->unlocked_ioctl)
+		rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
+	return rc;
+}
+
+#ifdef CONFIG_COMPAT
+static long
+ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct file *lower_file = NULL;
+	long rc = -ENOIOCTLCMD;
+
+	if (ecryptfs_file_to_private(file))
+		lower_file = ecryptfs_file_to_lower(file);
+	if (lower_file && lower_file->f_op && lower_file->f_op->compat_ioctl)
+		rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
+	return rc;
+}
+#endif
 
 const struct file_operations ecryptfs_dir_fops = {
 	.readdir = ecryptfs_readdir,
-	.ioctl = ecryptfs_ioctl,
+	.unlocked_ioctl = ecryptfs_unlocked_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl = ecryptfs_compat_ioctl,
+#endif
 	.open = ecryptfs_open,
 	.flush = ecryptfs_flush,
 	.release = ecryptfs_release,
@@ -313,7 +341,10 @@ const struct file_operations ecryptfs_main_fops = {
 	.write = do_sync_write,
 	.aio_write = generic_file_aio_write,
 	.readdir = ecryptfs_readdir,
-	.ioctl = ecryptfs_ioctl,
+	.unlocked_ioctl = ecryptfs_unlocked_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl = ecryptfs_compat_ioctl,
+#endif
 	.mmap = generic_file_mmap,
 	.open = ecryptfs_open,
 	.flush = ecryptfs_flush,
@@ -322,20 +353,3 @@ const struct file_operations ecryptfs_main_fops = {
 	.fasync = ecryptfs_fasync,
 	.splice_read = generic_file_splice_read,
 };
-
-static int
-ecryptfs_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
-	       unsigned long arg)
-{
-	int rc = 0;
-	struct file *lower_file = NULL;
-
-	if (ecryptfs_file_to_private(file))
-		lower_file = ecryptfs_file_to_lower(file);
-	if (lower_file && lower_file->f_op && lower_file->f_op->ioctl)
-		rc = lower_file->f_op->ioctl(ecryptfs_inode_to_lower(inode),
-					     lower_file, cmd, arg);
-	else
-		rc = -ENOTTY;
-	return rc;
-}