/lib/modules/3.2.0-126-generic/build is in linux-headers-3.2.0-126-generic 3.2.0-126.169.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/src/linux-headers-3.2.0-126-generic
/usr/src/linux-headers-3.2.0-126-generic