Technical data

Programming Release Notes
6.21 Privileged Interfaces and Data Structures (Alpha Only)
6.21 Privileged Interfaces and Data Structures (Alpha Only)
This section contains release notes concerning privileged code and data
structures.
6.21.1 Per-Thread Security and Backward Compatibility
V7.2
The security information previously stored in several data structures has moved
to a new Persona Security Block (PSB) data structure, making the relevant fields
in those structures obsolete in OpenVMS Version 7.2. The affected structures
include the Access Rights Block (ARB), Process Control Block (PCB), Process
Header Descriptor (PHD), Job Information Block (JIB), and Process Control
(CTL) region fields.
Table 6–1 shows the obsolete data cells and where the information in those cells
has moved.
For single persona execution within a process, the obsolete data cells are
maintained for backward compatibility. The cells are not maintained while a
process is executing with multiple user-level personae (because any code checking
the old cells would likely make the wrong security decision).
Note
Security information within the JIB (JIB$T_ACCOUNT, the account cell)
is not backward compatible because the JIB is shared among all processes
in a job tree. Modifying the JIB user-name cell (JIB$T_USERNAME) in a
multiprocess job tree can adversely affect other processes in that job tree.
Note
A process is created with a single user-mode security profile known as
the natural persona. Backward compatibility based on the current value
of the new SYSGEN parameter ARB_SUPPORT, which defines the level
of backward compatibility between the obsolete cells and the new PSB
data structure, is maintained while the process remains in this user-mode
persona state. (See the OpenVMS System Management Utilities Reference
Manual for information about the ARB_SUPPORT parameter.)
Backward compatibility is not supported when multiple user-mode
personae exist. Multiple user-mode personae are created using the
$PERSONA_CREATE system service.
Backward compatibility of the obsolete data cells may not be maintained in future
releases of OpenVMS. Writers of privileged code are encouraged to search for the
obsolete symbols in their code and make the necessary modifications to remove
the code’s dependence on the obsolete cells, and to obtain the information from
the new locations.
6–22 Programming Release Notes