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RHEL 9 must restrict exposed kernel pointer addresses access.


Overview

Finding ID Version Rule ID IA Controls Severity
V-257800 RHEL-09-213025 SV-257800r958514_rule Medium
Description
Exposing kernel pointers (through procfs or "seq_printf()") exposes kernel writeable structures, which may contain functions pointers. If a write vulnerability occurs in the kernel, allowing write access to any of this structure, the kernel can be compromised. This option disallows any program without the CAP_SYSLOG capability to get the addresses of kernel pointers by replacing them with "0". Satisfies: SRG-OS-000132-GPOS-00067, SRG-OS-000433-GPOS-00192, SRG-OS-000480-GPOS-00227
STIG Date
Red Hat Enterprise Linux 9 Security Technical Implementation Guide 2024-06-04

Details

Check Text ( C-61541r942970_chk )
Verify the runtime status of the kernel.kptr_restrict kernel parameter with the following command:

$ sudo sysctl kernel.kptr_restrict

kernel.kptr_restrict = 1

Verify the configuration of the kernel.kptr_restrict kernel parameter with the following command:

$ sudo /usr/lib/systemd/systemd-sysctl --cat-config | egrep -v '^(#|;)' | grep -F kernel.kptr_restrict | tail -1

kernel.kptr_restrict =1

If "kernel.kptr_restrict" is not set to "1" or is missing, this is a finding.
Fix Text (F-61465r925386_fix)
Add or edit the following line in a system configuration file in the "/etc/sysctl.d/" directory:

kernel.kptr_restrict = 1

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

$ sudo sysctl --system