eCryptfs: Handle NULL nameidata pointers

Allow for NULL nameidata pointers in eCryptfs create, lookup, and
d_revalidate functions.

Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>

fs/ecryptfs/dentry.c

@@ -46,24 +46,28 @@ static int ecryptfs_d_revalidate(struct dentry *dentry, struct nameidata *nd)
 {
 	struct dentry *lower_dentry;
 	struct vfsmount *lower_mnt;
-	struct dentry *dentry_save;
-	struct vfsmount *vfsmount_save;
+	struct dentry *dentry_save = NULL;
+	struct vfsmount *vfsmount_save = NULL;
 	int rc = 1;
 
-	if (nd->flags & LOOKUP_RCU)
+	if (nd && nd->flags & LOOKUP_RCU)
 		return -ECHILD;
 
 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
 	lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
 	if (!lower_dentry->d_op || !lower_dentry->d_op->d_revalidate)
 		goto out;
-	dentry_save = nd->path.dentry;
-	vfsmount_save = nd->path.mnt;
-	nd->path.dentry = lower_dentry;
-	nd->path.mnt = lower_mnt;
+	if (nd) {
+		dentry_save = nd->path.dentry;
+		vfsmount_save = nd->path.mnt;
+		nd->path.dentry = lower_dentry;
+		nd->path.mnt = lower_mnt;
+	}
 	rc = lower_dentry->d_op->d_revalidate(lower_dentry, nd);
-	nd->path.dentry = dentry_save;
-	nd->path.mnt = vfsmount_save;
+	if (nd) {
+		nd->path.dentry = dentry_save;
+		nd->path.mnt = vfsmount_save;
+	}
 	if (dentry->d_inode) {
 		struct inode *lower_inode =
 			ecryptfs_inode_to_lower(dentry->d_inode);

fs/ecryptfs/ecryptfs_kernel.h

@@ -632,8 +632,7 @@ int ecryptfs_interpose(struct dentry *hidden_dentry,
 		       u32 flags);
 int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry,
 					struct dentry *lower_dentry,
-					struct inode *ecryptfs_dir_inode,
-					struct nameidata *ecryptfs_nd);
+					struct inode *ecryptfs_dir_inode);
 int ecryptfs_decode_and_decrypt_filename(char **decrypted_name,
 					 size_t *decrypted_name_size,
 					 struct dentry *ecryptfs_dentry,

fs/ecryptfs/inode.c

@@ -74,16 +74,20 @@ ecryptfs_create_underlying_file(struct inode *lower_dir_inode,
 	unsigned int flags_save;
 	int rc;
 
-	dentry_save = nd->path.dentry;
-	vfsmount_save = nd->path.mnt;
-	flags_save = nd->flags;
-	nd->path.dentry = lower_dentry;
-	nd->path.mnt = lower_mnt;
-	nd->flags &= ~LOOKUP_OPEN;
+	if (nd) {
+		dentry_save = nd->path.dentry;
+		vfsmount_save = nd->path.mnt;
+		flags_save = nd->flags;
+		nd->path.dentry = lower_dentry;
+		nd->path.mnt = lower_mnt;
+		nd->flags &= ~LOOKUP_OPEN;
+	}
 	rc = vfs_create(lower_dir_inode, lower_dentry, mode, nd);
-	nd->path.dentry = dentry_save;
-	nd->path.mnt = vfsmount_save;
-	nd->flags = flags_save;
+	if (nd) {
+		nd->path.dentry = dentry_save;
+		nd->path.mnt = vfsmount_save;
+		nd->flags = flags_save;
+	}
 	return rc;
 }
 
@@ -241,8 +245,7 @@ out:
  */
 int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry,
 					struct dentry *lower_dentry,
-					struct inode *ecryptfs_dir_inode,
-					struct nameidata *ecryptfs_nd)
+					struct inode *ecryptfs_dir_inode)
 {
 	struct dentry *lower_dir_dentry;
 	struct vfsmount *lower_mnt;
@@ -290,8 +293,6 @@ int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry,
 		goto out;
 	if (special_file(lower_inode->i_mode))
 		goto out;
-	if (!ecryptfs_nd)
-		goto out;
 	/* Released in this function */
 	page_virt = kmem_cache_zalloc(ecryptfs_header_cache_2, GFP_USER);
 	if (!page_virt) {
@@ -417,8 +418,7 @@ static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode,
 	}
 lookup_and_interpose:
 	rc = ecryptfs_lookup_and_interpose_lower(ecryptfs_dentry, lower_dentry,
-						 ecryptfs_dir_inode,
-						 ecryptfs_nd);
+						 ecryptfs_dir_inode);
 	goto out;
 out_d_drop:
 	d_drop(ecryptfs_dentry);