[RFC] Virtual machine related events support

Marcelo Cerri
2011-11-12T06:26:26Z

Hi,

We are working on a project in which we need to get some events from
audit log related to virtual machine events and filter these events per
guests. Currently, the audit tools doesn't support this kind of search.
However we are willing to implement the necessary features to support it
and we'd like to receive some feedback from audit stakeholders on our
proposal.

Most of these records are generated by libvirt, but some of them are
generated by SELinux (as AVC denials). To get events generated by
libvirt, we'd like to search through audit records using the both "uuid"
and "vm" fields.
The following records are examples of both types of records that we
intend to filter:

type=VIRT_RESOURCE msg=audit(1319602467.134:33): user pid=14103 uid=0
auid=4294967295 ses=4294967295 msg='resrc=disk reason=start
vm="CentOS-Guest" uuid=41ffecd5-037e-0059-b074-ab2bf354fd0a old-disk="?"
new-disk="/var/lib/libvirt/images/CentOS-Guest.img":
exe="/usr/sbin/libvirtd" (hostname=?, addr=?, terminal=? res=success)'
type=AVC msg=audit(1318529059.690:801): avc: denied { read } for
pid=31199 comm="qemu-kvm" name="RHEL6.img" dev=dm-0 ino=524635
scontext=system_u:system_r:svirt_t:s0:c99,c999
tcontext=system_u:object_r:svirt_image_t:s0:c390,c835 tclass=file

While "vm" field contains the domain name and it's a more user friendly
identifier, it's intended to be a unique only within the scope of a
single host. On the other hand, "uuid" field is intended to be a global
identifier.

We'd like to create a stand-alone tool, similar to aulast, to filter
this kind of events and that could be part of audit's tools. It'd be
able to list VM specific events, and filter these events by UUID or VM
name if needed. We are intended to support the following usage/options
(any suggestions are welcome):

Usage: auvirt [ options ] [ uuid | vm-name ]

Options:

--summary(default)
Write a formatted output containing summarized information as
considered time period, total number of VM specific events,
total
number of events by type (start, stop, resource change) and
total
number of AVC events.

--raw
Write records related to guests as shown in audit.log. The
output may contain the following record types: VIRT_CONTROL,
VIRT_RESOURCE, VIRT_MACHINE_ID and AVC.

-f file, --stdin
Same as aulast.

We intend to correlate AVC denial events to guests through the security
label used by a guest in a specific period.

Another proposal would be change ausearch to support two new search
options:

-uu, --uuid vm-uuid
Search for an event with the given UUID.

-vm, --vm-name vm-name
Search for an event with the given virtual machine name.

However, these fields are defined by libvirt and it may be a good idea
to add to libaudit a new "audit_log_*" function to enforce a standard
message format for VM related events that could be used by other
virtualization tools.

Please, send your commentaries and suggestions.

Regards,
Marcelo Cerri