/usr/include/eigen3/Eigen/src/Eigen2Support/ is in libeigen3-dev 3.2.2-3.
This file is owned by root:root, with mode 0o755.
..
/usr/include/eigen3/Eigen/src/Eigen2Support/Block.h
/usr/include/eigen3/Eigen/src/Eigen2Support/Cwise.h
/usr/include/eigen3/Eigen/src/Eigen2Support/CwiseOperators.h
/usr/include/eigen3/Eigen/src/Eigen2Support/Geometry/
/usr/include/eigen3/Eigen/src/Eigen2Support/Geometry/AlignedBox.h
/usr/include/eigen3/Eigen/src/Eigen2Support/Geometry/All.h
/usr/include/eigen3/Eigen/src/Eigen2Support/Geometry/AngleAxis.h
/usr/include/eigen3/Eigen/src/Eigen2Support/Geometry/Hyperplane.h
/usr/include/eigen3/Eigen/src/Eigen2Support/Geometry/ParametrizedLine.h
/usr/include/eigen3/Eigen/src/Eigen2Support/Geometry/Quaternion.h
/usr/include/eigen3/Eigen/src/Eigen2Support/Geometry/Rotation2D.h
/usr/include/eigen3/Eigen/src/Eigen2Support/Geometry/RotationBase.h
/usr/include/eigen3/Eigen/src/Eigen2Support/Geometry/Scaling.h
/usr/include/eigen3/Eigen/src/Eigen2Support/Geometry/Transform.h
/usr/include/eigen3/Eigen/src/Eigen2Support/Geometry/Translation.h
/usr/include/eigen3/Eigen/src/Eigen2Support/LU.h
/usr/include/eigen3/Eigen/src/Eigen2Support/Lazy.h
/usr/include/eigen3/Eigen/src/Eigen2Support/LeastSquares.h
/usr/include/eigen3/Eigen/src/Eigen2Support/Macros.h
/usr/include/eigen3/Eigen/src/Eigen2Support/MathFunctions.h
/usr/include/eigen3/Eigen/src/Eigen2Support/Memory.h
/usr/include/eigen3/Eigen/src/Eigen2Support/Meta.h
/usr/include/eigen3/Eigen/src/Eigen2Support/Minor.h
/usr/include/eigen3/Eigen/src/Eigen2Support/QR.h
/usr/include/eigen3/Eigen/src/Eigen2Support/SVD.h
/usr/include/eigen3/Eigen/src/Eigen2Support/TriangularSolver.h
/usr/include/eigen3/Eigen/src/Eigen2Support/VectorBlock.h