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>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index ab429fe..150784e 100644 (file)
--- 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;

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 84c3b66..3814238 100644 (file)
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -589,6 +589,9 @@ static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
        int ret = 0;
        int len;
 
+       if (!capable(CAP_SYS_ADMIN))
+               return -EPERM;
+
        vol = kmalloc(sizeof(*vol), GFP_KERNEL);
        if (copy_from_user(vol, (void __user *)arg, sizeof(*vol))) {
                ret = -EFAULT;