Re: What fields should be used for reporting shared memory?

On Monday, March 20, 2017 7:36:14 AM EDT Martin Kletzander wrote: > On Thu, Mar 16, 2017 at 09:04:52PM -0400, Steve Grubb wrote: > >Hello, > > > >I apologize for the delay. > > > >On Tuesday, March 14, 2017 7:42:27 AM EDT Martin Kletzander wrote: > >> I am going through the fields in the dictionary and I can't find any > >> name to use for the following scenario. > >> > >> We (libvirt) are running virtual machines and there's a thing nowadays, > >> that people like to use, called ivshmem (Inter-VM SHared MEMory). From > >> host's point of view this is just a shared memory region accessed by > >> multiple VMs (and possibly to host as well). The machine maps the > >> shared memory given a name (e.g. name "asdf" results in /dev/shm/asdf to > >> be mapped) *or* it can communicate with a server over UNIX socket and > >> that server handles interrupts and also tells the client which shared > >> memory region to map. > > > >If both of these result in a path, then I think we want to log it as a > >resource event. > > Yes, and they both are resources in its sense. So you are talking > particularly about the resrc= field? Should that also have category and > class or anything else set? Or do you mean we report the path in the > resrc= field? No, I mean we would want the path to the memory in a VIRT_RESOURCE event. :-) How about something like this: type=VIRT_RESOURCE msg=audit(1488441043.591:2977): pid=25464 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:virtd_t:s0-s0:c0.c1023 msg='virt=kvm resrc=shmem reason=start vm="rhel7.3" uuid=a7708061- faa0-42ce-897a-e92fb75fcf1d size=4194304 path="/dev/shm/my_shmem1" exe="/usr/ sbin/libvirtd" hostname=? addr=? terminal=? res=success' Having the full path would make it more normal when reporting on files in use. > >> Talking about information we have; in server-less > >> setup it's the shared memory region that is shared, in the server > >> scenario it is the socket. That's information we can output. > > > >Above you mentioned that the server communicates which region to map. Can > >you explain what that means? > > The server sends a file descriptor to the VM over the socket, details > can be found here: > > http://git.qemu-project.org/?p=qemu.git;a=blob;f=docs/specs/ivshmem-spec.txt > #l151 This one is harder. What we really want to know is the size information. But libvirtd doesn't have it I assume. That makes it sound like ivshmem should log it, but it probably doesn't know the reason, vm name, or uuid or anything else. So, this is probably not good. I guess about all that you can say is that a ivshmem-socket is being assigned. I guess let's do it like this: type=VIRT_RESOURCE msg=audit(1488441043.591:2977): pid=25464 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:virtd_t:s0-s0:c0.c1023 msg='virt=kvm resrc=ivshmem-socket reason=start vm="rhel7.3" uuid=a7708061- faa0-42ce-897a-e92fb75fcf1d ivshmem="my_shmem2" exe="/usr/sbin/libvirtd" hostname=? addr=? terminal=? res=success'

-Steve > >> So my question is, when starting a domain or hot-(un)plugging, what > >> naming should we use for this kind of device and what are the things > >> that we should describe about it? Basically, how would you like the > >> message to look? > > > >We need a record recording what is getting assigned to the VM. In the case > >of the /dev/shm, you can record that as a path which must be escaped. In > >the case of the server, I think we still need to understand what is > >happening. Just recording a socket number or path is not terribly useful > >in reconstructing the resources given to the VM. > > > >Audit events have to tell a story. There is a subect, object, action, and > >results. It kind of needs to be a sentence. "libvirtd successfully assigned > >____ to vm-name." > > > >-Steve > > > >> Thanks in advance for any info. > >> > >> Have a nice day, > >> Martin