AlmaLinux OS 9 must enable hardening for the Berkeley Packet Filter (BPF) just-in-time (JIT) compiler.

When hardened, the extended BPF JIT compiler will randomize any kernel addresses in the BPF programs and maps, and will not expose the JIT addresses in "/proc/kallsyms".

Verify AlmaLinux OS 9 enables hardening for the BPF JIT with the following commands: $ 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. $ /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.

Configure AlmaLinux OS 9 to enable hardening for the BPF JIT compiler. Create a numbered *.conf file in /etc/sysctl.d/ with the following content: net.core.bpf_jit_harden = 2 The system configuration files must be reloaded for the changes to take effect. To reload the contents of the files, run the following command: $ sysctl –system