The "gitdiff" file is a patch for the coreboot project. Look at coreboot's copyright information
therefore to see what conditions the patch falls under.

Also, look at "getcb" script in a text editor in libreboot_src.tar.gz for this version of libreboot (go to ../../../docs/RELEASE.html
to find out how to get libreboot_src.tar.gz for this version of libreboot) for attribution (acknowledgement) of
the links to the original patches, since the gitdiff contains changes originally written by other people.