RHEL 9 must enable hardening for the Berkeley Packet Filter just-in-time compiler.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-257942	RHEL-09-251045	SV-257942r925813_rule		Medium

Description
When hardened, the extended Berkeley Packet Filter (BPF) just-in-time (JIT) compiler will randomize any kernel addresses in the BPF programs and maps, and will not expose the JIT addresses in "/proc/kallsyms".

STIG	Date
Red Hat Enterprise Linux 9 Security Technical Implementation Guide	2023-12-01

Details

Check Text ( C-61683r925811_chk )

Verify RHEL 9 enables hardening for the BPF JIT with the following commands: $ sudo sysctl net.core.bpf_jit_harden net.core.bpf_jit_harden = 2 If the returned line does not have a value of "2", or a line is not returned, this is a finding. Check that the configuration files are present to enable this kernel parameter. $ sudo /usr/lib/systemd/systemd-sysctl --cat-config | egrep -v '^(#|;)' | grep -F net.core.bpf_jit_harden | tail -1 net.core.bpf_jit_harden = 2 If the network parameter "net.core.bpf_jit_harden" is not equal to "2" or nothing is returned, this is a finding.

Fix Text (F-61607r925812_fix)
Configure RHEL 9 to enable hardening for the BPF JIT compiler by adding the following line to a file, in the "/etc/sysctl.d" directory: net.core.bpf_jit_harden = 2 The system configuration files need to be reloaded for the changes to take effect. To reload the contents of the files, run the following command: $ sudo sysctl --system