btrfs: call permission checks earlier in ioctls and return EPERM

The owner and capability checks in IOC_SUBVOL_SETFLAGS and
SET_RECEIVED_SUBVOL should be called before any other checks are done.

Also unify the error code to EPERM.

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 9 insertions, 13 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 8d4457f329f5..62c62b4fa55b 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -192,6 +192,9 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
         unsigned int i_oldflags;
         umode_t mode;
 
+        if (!inode_owner_or_capable(inode))
+                return -EPERM;
+
         if (btrfs_root_readonly(root))
                 return -EROFS;
 
@@ -202,9 +205,6 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
         if (ret)
                 return ret;
 
-        if (!inode_owner_or_capable(inode))
-                return -EACCES;
-
         ret = mnt_want_write_file(file);
         if (ret)
                 return ret;
@@ -1697,6 +1697,9 @@ static noinline int btrfs_ioctl_subvol_setflags(struct file *file,
         u64 flags;
         int ret = 0;
 
+        if (!inode_owner_or_capable(inode))
+                return -EPERM;
+
         ret = mnt_want_write_file(file);
         if (ret)
                 goto out;
@@ -1721,11 +1724,6 @@ static noinline int btrfs_ioctl_subvol_setflags(struct file *file,
                 goto out_drop_write;
         }
 
-        if (!inode_owner_or_capable(inode)) {
-                ret = -EACCES;
-                goto out_drop_write;
-        }
-
         down_write(&root->fs_info->subvol_sem);
 
         /* nothing to do */
@@ -4403,6 +4401,9 @@ static long btrfs_ioctl_set_received_subvol(struct file *file,
         int ret = 0;
         int received_uuid_changed;
 
+        if (!inode_owner_or_capable(inode))
+                return -EPERM;
+
         ret = mnt_want_write_file(file);
         if (ret < 0)
                 return ret;
@@ -4419,11 +4420,6 @@ static long btrfs_ioctl_set_received_subvol(struct file *file,
                 goto out;
         }
 
-        if (!inode_owner_or_capable(inode)) {
-                ret = -EACCES;
-                goto out;
-        }
-
         sa = memdup_user(arg, sizeof(*sa));
         if (IS_ERR(sa)) {
                 ret = PTR_ERR(sa);