RHEL 9 must restrict exposed kernel pointer addresses access.

Documentable No

Rule ID SV-257800r1155700_rule

CCI References

CCI-001082CCI-002824

Discussion

It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. The sysctl --system command will load settings from all system configuration files. All configuration files are sorted by their filename in lexicographical order, regardless of the directories in which they reside. If multiple files specify the same option, the entry in the file with the lexicographically latest name will take precedence. Files are read from directories in the following list from top to bottom. Once a file of a given filename is loaded, any file of the same name in subsequent directories is ignored. /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf /lib/sysctl.d/*.conf /etc/sysctl.conf Satisfies: SRG-OS-000132-GPOS-00067, SRG-OS-000433-GPOS-00192, SRG-OS-000480-GPOS-00227

Check Procedure

Verify RHEL 9 is configured to restrict exposed kernel pointer address access.

Verify the runtime status of the "kernel.kptr_restrict" kernel parameter with the following command:

$ sudo sysctl kernel.kptr_restrict 
kernel.kptr_restrict = 1

If "kernel.kptr_restrict" is not set to "1" or is missing, this is a finding.

Fix Action

Configure RHEL 9 to restrict exposed kernel pointer addresses access.

Create a drop-in if it does not already exist:

$ sudo vi /etc/sysctl.d/99-kernel_kptr_restrict.conf

Add the following to the file:
kernel.kptr_restrict = 1

Reload settings from all system configuration files with the following command:

$ sudo sysctl --system