Several aspects about how labels appear to users can be configured. Label visibility, label color, and labels on printed output can be configured. Some actions on labels require authorization or privilege. Upgrading or downgrading an object's label requires an authorization. Manipulating a label between its internal and its textual representation can require a privilege.
As described in Labeled Workspaces, labels appear on windows on the desktop. On a single-label system, you might not want labels to be visible. Label visibility is configurable in the policy.conf file for a system for individual users. For a pointer to the configuration procedures, see Managing Label Encodings (Task Map).
Typically, the content of files at a lower label can be read by a user at a higher label. For example, system files and commonly-available executables are assigned an ADMIN_LOW label. According to the read down-read equal rule, accounts who work at any label can read ADMIN_LOW files. As in the Solaris OS, DAC permissions can prevent read access. Zones also protect files from being read. If a lower-level zone is not mounted, a user in a higher-level zone cannot access the files for reading.
Files that contain data that should not be viewed by ordinary users, such as system log files and the label_encodings files, are maintained at ADMIN_HIGH. To allow administrators access to protected system files, the ADMIN_LOW and ADMIN_HIGH administrative labels are assigned as the minimum label and clearance for roles.
The labels that are printed on banner, trailer and body pages of print jobs can be customized. Also, accompanying text that appears on the banner and trailer pages can be customized. For more information, see Chapter 4, Labeling Printer Output (Tasks).
The authorization to upgrade information to a label that dominates the label of the current information is called the Upgrade File Label authorization. The authorization to downgrade information to a label that is lower than the the label of the current information is called the Downgrade File Label authorization. For definitions for these authorizations, see /etc/security/auth_attr.
Label translation occurs whenever programs manipulate labels. Labels are translated to and from the textual strings to the internal representation. For example, when a program such as getlabel gets the label of a file, before the label can display to the user, the internal representation of the label is translated into readable output. When the setlabel program sets a label specified on the command line, the textual string, that is, the label's name, is translated into the label's internal representation. Trusted Extensions permits label translations only if the calling process's label dominates the label that is to be translated. If a process attempts to translate a label that the process's label does not dominate, the translation is disallowed. The sys_trans_label privilege is required to override this restriction.