AlmaLinux OS 9 must enable hardening for the Berkeley Packet Filter (BPF) just-in-time (JIT) compiler.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-269273 | ALMA-09-021800 | SV-269273r1050155_rule | CCI-000366 | medium |
| Description | ||||
| 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". | ||||
| STIG | Date | |||
| CloudLinux AlmaLinux OS 9 Security Technical Implementation Guide | 2025-05-22 | |||
Details
Check Text (C-269273r1050155_chk)
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.
Fix Text (F-73205r1049420_fix)
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