USENIX Association Proceedings of the FREENIX Track: 2003 USENIX Annual Technical Conference San Antonio, Texas, USA June 9-14, 2003 THE ADVANCED COMPUTING SYSTEMS ASSOCIATION © 2003 by The USENIX Association All Rights Reserved For more information about the USENIX Association: Phone: 1 510 528 8649 FAX: 1 510 548 5738 Email:
[email protected] WWW: http://www.usenix.org Rights to individual papers remain with the author or the author's employer. Permission is granted for noncommercial reproduction of the work for educational or research purposes. This copyright notice must be included in the reproduced paper. USENIX acknowledges all trademarks herein. POSIX Access Control Lists on Linux Andreas Grunbacher¨ SuSE Labs, SuSE Linux AG Nuremberg, Germany
[email protected] Abstract This paper gives an overview of the most successful ACL scheme for UNIX-like systems that has resulted This paper discusses file system Access Control Lists from the POSIX 1003.1e/1003.2c working group. as implemented in several UNIX-like operating systems. After briefly describing the concepts, some examples After recapitulating the concepts of these Access Con- of how these are used are given for better understanding. trol Lists that never formally became a POSIX standard, Following that, the paper discusses Extended Attributes, we focus on the different aspects of implementation and the abstraction layer upon which ACLs are based on use on Linux. Linux. The rest of the paper deals with implementation, performance, interoperability, application support, and 1 Introduction