/usr/include/mongo/db/auth/ is in mongodb-dev 1:2.4.9-1ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/mongo/db/auth/action_set.h
/usr/include/mongo/db/auth/action_type.h
/usr/include/mongo/db/auth/auth_external_state.h
/usr/include/mongo/db/auth/auth_external_state_d.h
/usr/include/mongo/db/auth/auth_external_state_mock.h
/usr/include/mongo/db/auth/auth_external_state_s.h
/usr/include/mongo/db/auth/auth_external_state_server_common.h
/usr/include/mongo/db/auth/auth_index_d.h
/usr/include/mongo/db/auth/authentication_session.h
/usr/include/mongo/db/auth/authorization_manager.h
/usr/include/mongo/db/auth/mongo_authentication_session.h
/usr/include/mongo/db/auth/principal.h
/usr/include/mongo/db/auth/principal_name.h
/usr/include/mongo/db/auth/principal_set.h
/usr/include/mongo/db/auth/privilege.h
/usr/include/mongo/db/auth/privilege_set.h
/usr/include/mongo/db/auth/security_key.h