Documentation/config/tar.txt

   1 tar.umask::
   2         This variable can be used to restrict the permission bits of
   3         tar archive entries.  The default is 0002, which turns off the
   4         world write bit.  The special value "user" indicates that the
   5         archiving user's umask will be used instead.  See umask(2) and
   6         linkgit:git-archive[1].