audit_warn Script

The /etc/security/audit_warn script notifies an email alias when the auditd daemon encounters an unusual condition while writing audit records. You can customize this script for your site to warn of conditions that might require manual intervention. Or, you could specify how to handle those conditions automatically. For all error conditions, the audit_warn script writes a message to syslog with the severity of daemon.alert. You can use syslog.conf to configure console display of syslog messages. The audit_warn script also sends a message to the audit_warn email alias. You set up this alias as part of audit configuration.

When the auditd daemon detects the following conditions, the daemon invokes the audit_warn script. The script sends email to the audit_warn alias.

• An audit directory has become more full than the p_minfree value allows. The p_minfree value or soft limit is a percentage of the available space on an audit file system.

  The audit_warn script is invoked with the string soft and the name of the directory whose available space is below the minimum value. The auditd daemon switches automatically to the next suitable directory. The daemon writes the audit files in this new directory until the directory reaches its minfree limit. The auditd daemon then goes to each remaining directory in the order that is listed in the audit_control file. The daemon writes audit records until each directory is at its minfree limit.

• All the audit directories have reached the minfree threshold.

  The audit_warn script is invoked with the string allsoft. A message is written to the console. Email is also sent to the audit_warn alias.

  When all audit directories that are listed in the audit_control file have reached their minfree threshold, the auditd daemon switches back to the first directory. The daemon writes audit records until the directory becomes completely full.

• An audit directory has become completely full with no space remaining.

  The audit_warn script is invoked with the string hard and the name of the directory. A message is written to the console. Email is also sent to the audit_warn alias.

  The auditd daemon switches automatically to the next suitable directory with any space available. The auditd daemon goes to each remaining directory in the order that is listed in the audit_control file. The daemon writes audit records until each directory is full.

• All the audit directories are completely full. The audit_warn script is invoked with the string allhard as an argument.

  By default, a message is written to the console. Email is also sent to the audit_warn alias. Processes that would otherwise generate audit records continue to occur, but audit records are counted. Audit records are not generated. For an example of how to handle this situation, see Example 30–13 and How to Prevent Audit Trail Overflow.

• An internal error occurs. Possible internal errors include the following:

  • ebusy – Another auditd daemon process is already running

  • tmpfile – A temporary file cannot be used

  • postsigterm – A signal was received during auditing shutdown

  • plugin name – An error occurred during execution of the plugin

• A problem is discovered with the syntax of the audit_control file. By default, a message is sent to the console. Email is also sent to the audit_warn alias.

If the perzone audit policy is set, the non-global zone's instance of auditd calls the zone's audit_warn script. For further information, see the audit_warn(1M) man page.