Re: [PATCH v3] vfs: new O_NODE open flag

[Miklos Szeredi]

On Wed, 2 Dec 2009, Alan Cox wrote:
> > 1) There's a security hole with dynamicly allocated devices if
> > permissions on new device are difference than on old device.
> > 
> > The issue is valid, but also exists if hard links are created to
> > device nodes.  udev already defends against this by setting
> > permissions on device to zero before unlinking it.
> 
> udev defends against it with the specific knowledge that any existing
> open means the device is open and cannot be unloaded. The combination is
> required (and some other happenstance properties).

You're still missing the point.  O_NODE is like a hard link, except
the reference doesn't come from the filesystem but from a file
descriptor.  From udev's perspective there's no difference.

Miklos
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/