/usr/include/gfal2/ is in libgfal2-dev 2.15.2-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/gfal2/common/
/usr/include/gfal2/common/gfal_cancel.h
/usr/include/gfal2/common/gfal_common.h
/usr/include/gfal2/common/gfal_config.h
/usr/include/gfal2/common/gfal_constants.h
/usr/include/gfal2/common/gfal_cred_mapping.h
/usr/include/gfal2/common/gfal_deprecated.h
/usr/include/gfal2/common/gfal_error.h
/usr/include/gfal2/common/gfal_file_handle.h
/usr/include/gfal2/common/gfal_plugin.h
/usr/include/gfal2/common/gfal_plugin_interface.h
/usr/include/gfal2/file/
/usr/include/gfal2/file/gfal_file_api.h
/usr/include/gfal2/gfal_api.h
/usr/include/gfal2/gfal_plugins_api.h
/usr/include/gfal2/logger/
/usr/include/gfal2/logger/gfal_logger.h
/usr/include/gfal2/posix/
/usr/include/gfal2/posix/gfal_posix_api.h
/usr/include/gfal2/transfer/
/usr/include/gfal2/transfer/gfal_transfer.h
/usr/include/gfal2/transfer/gfal_transfer_plugins.h
/usr/include/gfal2/utils/
/usr/include/gfal2/utils/gfal2_uri.h