All files in DNF are distributed as GPLv2+ with the exceptions below:

rpm/transaction.py : GPL

Licensing conditions of the following files were disputed when DNF was forked
from YUM:

yum/misc.py
yum/parser.py

In the yum-devel-list-thread below those concernes were resolved by YUM
maintainers who confirmed these files were covered by GPLv2+:

http://lists.baseurl.org/pipermail/yum-devel/2012-July/009376.html