Audit messages may be lost during boot

This document (000020867) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 15 (All Service Packs)
SUSE Linux Enterprise Server for SAP Applications 15 (All Service packs)

Situation

Hold queue overflow messages are observed in the kernel ring buffer and system logs which may indicate lost auditing messages during boot and before auditd.service is started.

# dmesg | grep overflow
[    0.289646] audit: kauditd hold queue overflow
[    0.364107] audit: kauditd hold queue overflow


The audit sub-system is enabled at boot as confirmed by audit=1 on the /proc/cmdline.

# cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-5.14.21-150400.24.28-default root=/dev/mapper/system-root nosplash mitigations=auto security=apparmor crashkernel=228M,high crashkernel=72M,low audit=1


The security auditing service is enabled.

# systemctl is-enabled auditd.service
enabled

 

Resolution

Do the following:
  1. Edit /etc/default/grub
  2. Append audit_backlog_limit=8192 right after audit=1 to GRUB_CMDLINE_LINUX and save
  3. Run update-bootloader to update the boot settings
  4. Reboot the system for changes to take affect

Cause

Booting with the audit=1 parameter uses a default audit_backlog_limit of 64. It sets the maximum number of audit messages that can be held before the auditd service starts and takes over. When the number of audit messages exceed the backlog limit you see the overflow messages.

 

Additional Information

TID000019031 - Enable auditing of processes that start prior to auditd explains how to enable auditing before the auditd service is started.
If you have the kernel-source package installed, see audit= in /usr/src/linux/Documentation/admin-guide/kernel-parameters.txt

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:000020867
  • Creation Date: 22-Nov-2022
  • Modified Date:23-Nov-2022
    • SUSE Linux Enterprise Server
    • SUSE Linux Enterprise Server for SAP Applications

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