Btrfs: add permission checks to the ioctls

Only root can add/remove devices
Only root can defrag subtrees
Only files open for writing can be defragged
Only files open for writing can be the destination for a clone

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 23 insertions, 2 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index ab429fe0fa0f..150784e936e6 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -453,6 +453,9 @@ static int btrfs_ioctl_resize(struct btrfs_root *root, void __user *arg)
         if (root->fs_info->sb->s_flags & MS_RDONLY)
                 return -EROFS;
 
+        if (!capable(CAP_SYS_ADMIN))
+                return -EPERM;
+
         vol_args = kmalloc(sizeof(*vol_args), GFP_NOFS);
 
         if (!vol_args)
@@ -638,16 +641,24 @@ static int btrfs_ioctl_defrag(struct file *file)
 
         switch (inode->i_mode & S_IFMT) {
         case S_IFDIR:
+                if (!capable(CAP_SYS_ADMIN)) {
+                        ret = -EPERM;
+                        goto out;
+                }
                 btrfs_defrag_root(root, 0);
                 btrfs_defrag_root(root->fs_info->extent_root, 0);
                 break;
         case S_IFREG:
+                if (!(file->f_mode & FMODE_WRITE)) {
+                        ret = -EINVAL;
+                        goto out;
+                }
                 btrfs_defrag_file(file);
                 break;
         }
-
+out:
         mnt_drop_write(file->f_path.mnt);
-        return 0;
+        return ret;
 }
 
 static long btrfs_ioctl_add_dev(struct btrfs_root *root, void __user *arg)
@@ -655,6 +666,9 @@ static long btrfs_ioctl_add_dev(struct btrfs_root *root, void __user *arg)
         struct btrfs_ioctl_vol_args *vol_args;
         int ret;
 
+        if (!capable(CAP_SYS_ADMIN))
+                return -EPERM;
+
         vol_args = kmalloc(sizeof(*vol_args), GFP_NOFS);
 
         if (!vol_args)
@@ -677,6 +691,9 @@ static long btrfs_ioctl_rm_dev(struct btrfs_root *root, void __user *arg)
         struct btrfs_ioctl_vol_args *vol_args;
         int ret;
 
+        if (!capable(CAP_SYS_ADMIN))
+                return -EPERM;
+
         if (root->fs_info->sb->s_flags & MS_RDONLY)
                 return -EROFS;
 
@@ -726,6 +743,10 @@ static long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
          *   they don't overlap)?
          */
 
+        /* the destination must be opened for writing */
+        if (!(file->f_mode & FMODE_WRITE))
+                return -EINVAL;
+
         ret = mnt_want_write(file->f_path.mnt);
         if (ret)
                 return ret;