Chapter 20. Access Control Lists
Files and directories have permission sets for the owner of the file, the group associated with the file, and all other users for the system. However, these permission sets have limitations. For example, different permissions cannot be configured for different users. Thus, Access Control Lists (ACLs) were implemented.
The Red Hat Enterprise Linux kernel provides ACL support for the ext3 file system and NFS-exported file systems. ACLs are also recognized on ext3 file systems accessed via Samba.
Along with support in the kernel, the
aclpackage is required to implement ACLs. It contains the utilities used to add, modify, remove, and retrieve ACL information.
mvcommands copy or move any ACLs associated with files and directories.
20.1. Mounting File Systems
Before using ACLs for a file or directory, the partition for the file or directory must be mounted with ACL support. If it is a local ext3 file system, it can mounted with the following command:
mount -t ext3 -o acl device-name partition
mount -t ext3 -o acl /dev/VolGroup00/LogVol02 /work
Alternatively, if the partition is listed in the
/etc/fstabfile, the entry for the partition can include the
LABEL=/work /work ext3 acl 1 2
If an ext3 file system is accessed via Samba and ACLs have been enabled for it, the ACLs are recognized because Samba has been compiled with the
--with-acl-supportoption. No special flags are required when accessing or mounting a Samba share.