AlmaLinux OS 9 must disable access to network bpf system call from nonprivileged processes.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-269422 | ALMA-09-040720 | SV-269422r1050305_rule | CCI-001082 | medium |
| Description | ||||
| Loading and accessing the packet filters programs and maps using the bpf() system call has the potential of revealing sensitive information about the kernel state. | ||||
| STIG | Date | |||
| CloudLinux AlmaLinux OS 9 Security Technical Implementation Guide | 2025-05-22 | |||
Details
Check Text (C-269422r1050305_chk)
Verify AlmaLinux OS 9 prevents privilege escalation thru the kernel by disabling access to the bpf system call with the following commands:
$ sysctl kernel.unprivileged_bpf_disabled
kernel.unprivileged_bpf_disabled = 1
If the returned line does not have a value of "1", 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 kernel.unprivileged_bpf_disabled | tail -1
kernel.unprivileged_bpf_disabled = 1
If "kernel.unprivileged_bpf_disabled" is not set to "1", or nothing is returned, this is a finding.
Fix Text (F-73354r1049678_fix)
Configure AlmaLinux OS 9 to prevent privilege escalation through the kernel by disabling access to the bpf syscall with the following command:
$ echo "kernel.unprivileged_bpf_disabled = 1" > /etc/sysctl.d/60-bpf.conf
Load settings from all system configuration files with the following command:
$ sysctl --system