Securing the AliEn File Catalogue - Enforcing authorization with accountable file operations
Steffen Schreiner, S. Bagnasco, Subho Sankar Banerjee, L. Betev, Federico Carminati, Olga Vladimirovna Datskova, Fabrizio Furano, Alina Gabriela Grigoras, C. Grigoras, Patricia Mendez Lorenzo, Andreas Joachim Peters, Pablo Sáiz, Jianlin Zhu · Journal of Physics Conference Series · 2011
The AliEn Grid Services, as operated by the ALICE Collaboration in its global physics analysis grid framework, is based on a central File Catalogue together with a distributed set of storage systems and the possibility to register links to external data resources. This paper describes several identified vulnerabilities in the AliEn File Catalogue access protocol regarding fraud and unauthorized file alteration and presents a more secure and revised design: a new mechanism, called LFN Booking Table, is introduced in order to keep track of access authorization in the transient state of files entering or leaving the File Catalogue. Due to a simplification of the original Access Envelope mechanism for xrootd-protocol-based storage systems, fundamental computational improvements of the mechanism were achieved as well as an up to 50% reduction of the credential's size. By extending the access protocol with signed status messages from the underlying storage system, the File Catalogue receives trusted information about a file's size and checksum and the protocol is no longer dependent on client trust. Altogether, the revised design complies with atomic and consistent transactions and allows for accountable, authentic, and traceable file operations. This paper describes these changes as part and beyond the development of AliEn version 2.19.