Audit log
Introduction
A number of the libvirt virtualization drivers (QEMU/KVM and LXC) include support for logging details of important operations to the host's audit subsystem. This provides administrators / auditors with a canonical historical record of changes to virtual machines' / containers' lifecycle states and their configuration. On hosts which are running the Linux audit daemon, the logs will usually end up in /var/log/audit/audit.log
Configuration
The libvirt audit integration is enabled by default on any host which has the Linux audit subsystem active, and disabled otherwise. It is possible to alter this behaviour in the /etc/libvirt/libvirtd.conf configuration file, via the audit_level parameter
- audit_level=0 - libvirt auditing is disabled regardless of host audit subsystem enablement. 
- audit_level=1 - libvirt auditing is enabled if the host audit subsystem is enabled, otherwise it is disabled. This is the default behaviour. 
- audit_level=2 - libvirt auditing is enabled regardless of host audit subsystem enablement. If the host audit subsystem is disabled, then libvirtd will refuse to complete startup and exit with an error. 
In addition to have formal messages sent to the audit subsystem it is possible to tell libvirt to inject messages into its own logging layer. This will result in messages ending up in the systemd journal or /var/log/libvirt/libvirtd.log on non-systemd hosts. This is disabled by default, but can be requested by setting the audit_logging=1 configuration parameter in the same file mentioned above.
Message types
Libvirt defines three core audit message types each of which will be described below. There are a number of common fields that will be reported for all message types.
- pid
- Process ID of the libvirtd daemon generating the audit record. 
- uid
- User ID of the libvirtd daemon process generating the audit record. 
- subj
- Security context of the libvirtd daemon process generating the audit record. 
- msg
- String containing a list of key=value pairs specific to the type of audit record being reported. 
Some fields in the msg string are common to audit records
- virt
- Type of virtualization driver used. One of qemu or lxc 
- vm
- Host driver unique name of the guest 
- uuid
- Globally unique identifier for the guest 
- exe
- Path of the libvirtd daemon 
- hostname
- Currently unused 
- addr
- Currently unused 
- terminal
- Currently unused 
- res
- Result of the action, either success or failed 
VIRT_CONTROL
Reports change in the lifecycle state of a virtual machine. The msg field will include the following sub-fields
- op
- Type of operation performed. One of start, stop or init 
- reason
- The reason which caused the operation to happen 
- vm-pid
- ID of the primary/leading process associated with the guest 
- init-pid
- ID of the init process in a container. Only if op=init and virt=lxc 
- pid-ns
- Namespace ID of the init process in a container. Only if op=init and virt=lxc 
VIRT_MACHINE_ID
Reports the association of a security context with a guest. The msg field will include the following sub-fields
- model
- The security driver type. One of selinux or apparmor 
- vm-ctx
- Security context for the guest process 
- img-ctx
- Security context for the guest disk images and other assigned host resources 
VIRT_RESOURCE
Reports the usage of a host resource by a guest. The fields include will vary according to the type of device being reported. When the guest is initially booted records will be generated for all assigned resources. If any changes are made to the running guest configuration, for example hotplug devices, or adjust resources allocation, further records will be generated.
Virtual CPU
The msg field will include the following sub-fields
- reason
- The reason which caused the resource to be assigned to happen 
- resrc
- The type of resource assigned. Set to vcpu 
- old-vcpu
- Original vCPU count, or 0 
- new-vcpu
- Updated vCPU count 
Memory
The msg field will include the following sub-fields
- reason
- The reason which caused the resource to be assigned to happen 
- resrc
- The type of resource assigned. Set to mem 
- old-mem
- Original memory size in bytes, or 0 
- new-mem
- Updated memory size in bytes 
Disk
The msg field will include the following sub-fields
- reason
- The reason which caused the resource to be assigned to happen 
- resrc
- The type of resource assigned. Set to disk 
- old-disk
- Original host file or device path acting as the disk backing file 
- new-disk
- Updated host file or device path acting as the disk backing file 
Network interface
The msg field will include the following sub-fields
- reason
- The reason which caused the resource to be assigned to happen 
- resrc
- The type of resource assigned. Set to net 
- old-net
- Original MAC address of the guest network interface 
- new-net
- Updated MAC address of the guest network interface 
If there is a host network interface associated with the guest NIC then further records may be generated
- reason
- The reason which caused the resource to be assigned to happen 
- resrc
- The type of resource assigned. Set to net 
- net
- MAC address of the host network interface 
- rdev
- Name of the host network interface 
Filesystem
The msg field will include the following sub-fields
- reason
- The reason which caused the resource to be assigned to happen 
- resrc
- The type of resource assigned. Set to fs 
- old-fs
- Original host directory, file or device path backing the filesystem 
- new-fs
- Updated host directory, file or device path backing the filesystem 
Host device
The msg field will include the following sub-fields
- reason
- The reason which caused the resource to be assigned to happen 
- resrc
- The type of resource assigned. Set to hostdev or dev 
- dev
- The unique bus identifier of the USB, PCI or SCSI device, if resrc=dev 
- disk
- The path of the block device assigned to the guest, if resrc=hostdev 
- chardev
- The path of the character device assigned to the guest, if resrc=hostdev 
TPM
The msg field will include the following sub-fields
- reason
- The reason which caused the resource to be assigned to happen 
- resrc
- The type of resource assigned. Set to tpm or tpm-emulator 
- device
- The path of the host TPM device assigned to the guest 
RNG
The msg field will include the following sub-fields
- reason
- The reason which caused the resource to be assigned to happen 
- resrc
- The type of resource assigned. Set to rng 
- old-rng
- Original path of the host entropy source for the RNG 
- new-rng
- Updated path of the host entropy source for the RNG 
console/serial/parallel/channel
The msg field will include the following sub-fields
- reason
- The reason which caused the resource to be assigned to happen 
- resrc
- The type of resource assigned. Set to chardev 
- old-chardev
- Original path of the backing character device for given emulated device 
- new-chardev
- Updated path of the backing character device for given emulated device 
smartcard
The msg field will include the following sub-fields
- reason
- The reason which caused the resource to be assigned to happen 
- resrc
- The type of resource assigned. Set to smartcard 
- old-smartcard
- Original path of the backing character device, certificate store or "nss-smartcard-device" for host smartcard passthrough. 
- new-smartcard
- Updated path of the backing character device, certificate store or "nss-smartcard-device" for host smartcard passthrough. 
Redirected device
The msg field will include the following sub-fields
- reason
- The reason which caused the resource to be assigned to happen 
- resrc
- The type of resource assigned. Set to redir 
- bus
- The bus type, only usb allowed 
- device
- The device type, only USB redir allowed 
Control group
The msg field will include the following sub-fields
- reason
- The reason which caused the resource to be assigned to happen 
- resrc
- The type of resource assigned. Set to cgroup 
- cgroup
- The name of the cgroup controller