linux-kernel - Re: [PATCH] vhost/vsock: specify module version

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAEivzxfX-H15e6Lt78F0_Rkp=g5QnmDH4Z3m8z7imNFaKcL6TQ@mail.gmail.com>
Date: Sun, 29 Sep 2024 20:23:29 +0200
From: Aleksandr Mikhalitsyn <aleksandr.mikhalitsyn@...onical.com>
To: "Michael S. Tsirkin" <mst@...hat.com>
Cc: stefanha@...hat.com, Stefano Garzarella <sgarzare@...hat.com>, 
	Jason Wang <jasowang@...hat.com>, Eugenio Pérez <eperezma@...hat.com>, 
	kvm@...r.kernel.org, virtualization@...ts.linux.dev, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] vhost/vsock: specify module version

On Sun, Sep 29, 2024 at 7:48 PM Michael S. Tsirkin <mst@...hat.com> wrote:
>
> On Sun, Sep 29, 2024 at 07:35:35PM +0200, Aleksandr Mikhalitsyn wrote:
> > On Sun, Sep 29, 2024 at 6:56 PM Michael S. Tsirkin <mst@...hat.com> wrote:
> > >
> > > On Thu, Sep 26, 2024 at 06:16:40PM +0200, Alexander Mikhalitsyn wrote:
> > > > Add an explicit MODULE_VERSION("0.0.1") specification
> > > > for a vhost_vsock module. It is useful because it allows
> > > > userspace to check if vhost_vsock is there when it is
> > > > configured as a built-in.
> > > >
> > > > Without this change, there is no /sys/module/vhost_vsock directory.
> > > >
> > > > With this change:
> > > > $ ls -la /sys/module/vhost_vsock/
> > > > total 0
> > > > drwxr-xr-x   2 root root    0 Sep 26 15:59 .
> > > > drwxr-xr-x 100 root root    0 Sep 26 15:59 ..
> > > > --w-------   1 root root 4096 Sep 26 15:59 uevent
> > > > -r--r--r--   1 root root 4096 Sep 26 15:59 version
> > > >
> > > > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@...onical.com>
> > >
> > >
> >
> > Dear Michael,
> >
> > > Why not check that the misc device is registered?
> >
> > It is possible to read /proc/misc and check if "241 vhost-vsock" is
> > there, but it means that userspace
> > needs to have a specific logic for vsock. At the same time, it's quite
> > convenient to do something like:
> >     if [ ! -d /sys/modules/vhost_vsock ]; then
> >         modprobe vhost_vsock
> >     fi
> >
> > > I'd rather not add a new UAPI until actually necessary.
> >
> > I don't insist. I decided to send this patch because, while I was
> > debugging a non-related kernel issue
> > on my local dev environment I accidentally discovered that LXD
> > (containers and VM manager)
> > fails to run VMs because it fails to load the vhost_vsock module (but
> > it was built-in in my debug kernel
> > and the module file didn't exist). Then I discovered that before
> > trying to load a module we
> > check if /sys/module/<module name> exists. And found that, for some
> > reason /sys/module/vhost_vsock
> > does not exist when vhost_vsock is configured as a built-in, and
> > /sys/module/vhost_vsock *does* exist when
> > vhost_vsock is loaded as a module. It looks like an inconsistency and
> > I also checked that other modules in
> > drivers/vhost have MODULE_VERSION specified and version is 0.0.1. I
> > thought that this change looks legitimate
> > and convenient for userspace consumers.
> >
> > Kind regards,
> > Alex
>
>
> I'll ask you to put this explanation in the commit log,
> and I'll pick this up.

Have done:
https://lore.kernel.org/kvm/20240929182103.21882-1-aleksandr.mikhalitsyn@canonical.com

Thanks, Michael!

Kind regards,
Alex

>
> > >
> > > > ---
> > > >  drivers/vhost/vsock.c | 1 +
> > > >  1 file changed, 1 insertion(+)
> > > >
> > > > diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> > > > index 802153e23073..287ea8e480b5 100644
> > > > --- a/drivers/vhost/vsock.c
> > > > +++ b/drivers/vhost/vsock.c
> > > > @@ -956,6 +956,7 @@ static void __exit vhost_vsock_exit(void)
> > > >
> > > >  module_init(vhost_vsock_init);
> > > >  module_exit(vhost_vsock_exit);
> > > > +MODULE_VERSION("0.0.1");
> > > >  MODULE_LICENSE("GPL v2");
> > > >  MODULE_AUTHOR("Asias He");
> > > >  MODULE_DESCRIPTION("vhost transport for vsock ");
> > > > --
> > > > 2.34.1
> > >
>