On Fri, May 11, 2018 at 12:26:50PM -0700, Mark Fasheh wrote: > The permission check in vfs_dedupe_file_range() is too coarse - We > only allow dedupe of the destination file if the user is root, or > they have the file open for write. > > This effectively limits a non-root user from deduping their own > read-only files. As file data during a dedupe does not change, > this is unexpected behavior and this has caused a number of issue > reports. For an example, see: > > https://github.com/markfasheh/duperemove/issues/129 > > So change the check so we allow dedupe on the target if: > > - the root or admin is asking for it > - the owner of the file is asking for the dedupe > - the process has write access > > Signed-off-by: Mark Fasheh <mfasheh@xxxxxxx> Sounds fine I guess.... Acked-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> --D > --- > fs/read_write.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/read_write.c b/fs/read_write.c > index c4eabbfc90df..77986a2e2a3b 100644 > --- a/fs/read_write.c > +++ b/fs/read_write.c > @@ -2036,7 +2036,8 @@ int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same) > > if (info->reserved) { > info->status = -EINVAL; > - } else if (!(is_admin || (dst_file->f_mode & FMODE_WRITE))) { > + } else if (!(is_admin || (dst_file->f_mode & FMODE_WRITE) || > + uid_eq(current_fsuid(), dst->i_uid))) { > info->status = -EINVAL; > } else if (file->f_path.mnt != dst_file->f_path.mnt) { > info->status = -EXDEV; > -- > 2.15.1 >
