/usr/share/matplotlib/mpl-data/fonts/pdfcorefonts/ is in python-matplotlib-data 2.1.1-2ubuntu3.
This file is owned by root:root, with mode 0o755.
..
/usr/share/matplotlib/mpl-data/fonts/pdfcorefonts/Courier-Bold.afm
/usr/share/matplotlib/mpl-data/fonts/pdfcorefonts/Courier-BoldOblique.afm
/usr/share/matplotlib/mpl-data/fonts/pdfcorefonts/Courier-Oblique.afm
/usr/share/matplotlib/mpl-data/fonts/pdfcorefonts/Courier.afm
/usr/share/matplotlib/mpl-data/fonts/pdfcorefonts/Helvetica-Bold.afm
/usr/share/matplotlib/mpl-data/fonts/pdfcorefonts/Helvetica-BoldOblique.afm
/usr/share/matplotlib/mpl-data/fonts/pdfcorefonts/Helvetica-Oblique.afm
/usr/share/matplotlib/mpl-data/fonts/pdfcorefonts/Helvetica.afm
/usr/share/matplotlib/mpl-data/fonts/pdfcorefonts/Symbol.afm
/usr/share/matplotlib/mpl-data/fonts/pdfcorefonts/Times-Bold.afm
/usr/share/matplotlib/mpl-data/fonts/pdfcorefonts/Times-BoldItalic.afm
/usr/share/matplotlib/mpl-data/fonts/pdfcorefonts/Times-Italic.afm
/usr/share/matplotlib/mpl-data/fonts/pdfcorefonts/Times-Roman.afm
/usr/share/matplotlib/mpl-data/fonts/pdfcorefonts/ZapfDingbats.afm