auditd stops sending audit messages of NFS share

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Environment

SUSE Linux Enterprise Server 15 all service packs
SUSE Linux Enterprise Server 12 all service packs

Situation

auditd is configured to monitor a NFS share, let's say /sap with sap-nfs key, as follows audit.rules

-w /sap -p rwxa -k sap-nfs

However when the share is unmounted and mounted again, no more logs are recorded and the following message is seen

audit: type=1305 : op=remove_rule dir="/sap" key="sap-nfs" list=4 res=1

Resolution

Restart audit after unmounting/mounting a NFS share. However, with systemd, this can be automated with the following service on-sap-nfs-mount.service

[Unit]
RequiresMountsFor=/sap
BindsTo=sap.mount

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/bin/sh -c "/usr/sbin/auditctl -w /sap -p rwxa -k sap-nfs || true"
[Install]
WantedBy=sap.mount

copy the service file to /etc/systemd/system/

systemctl enable --now on-sap-nfs-mount

With that, auditctl is executed to reload the rules for the NFS share that is being mounted back.

Cause

This occurs because when the NFS share is unmounted, audit removes its corresponding rules, when it is mounted again, audit doesn't know about it and so no logs are being recorded.

Disclaimer

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