Messages in this thread | | | From | (Eric W. Biederman) | Date | Fri, 16 May 2014 21:31:37 -0700 | Subject | Re: [lxc-devel] [RFC PATCH 00/11] Add support for devtmpfs in user namespaces |
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Greg Kroah-Hartman <gregkh@linuxfoundation.org> writes:
> On Fri, May 16, 2014 at 01:49:59AM +0000, Serge Hallyn wrote: >> > I think having to pick and choose what device nodes you want in a >> > container is a good thing. Becides, you would have to do the same thing >> > in the kernel anyway, what's wrong with userspace making the decision >> > here, especially as it knows exactly what it wants to do much more so >> > than the kernel ever can. >> >> For 'real' devices that sounds sensible. The thing about loop devices >> is that we simply want to allow a container to say "give me a loop >> device to use" and have it receive a unique loop device (or 3), without >> having to pre-assign them. I think that would be cleaner to do using >> a pseudofs and loop-control device, rather than having to have a >> daemon in userspace on the host farming those out in response to >> some, I don't know, dbus request? > > I agree that loop devices would be nice to have in a container, and that > the existing loop interface doesn't really lend itself to that. So > create a new type of thing that acts like a loop device in a container. > But don't try to mess with the whole driver core just for a single type > of device.
Yes. Something like devpts (without the newinstance option). Built to allow unprivileged users to create loopback devices.
There is still a huge kettle of fish in with verifying a filesystem is safe from a hostile user that has acess to the block device while the filesystem is mounted.
Having a few filesystems that are robust enough to trust with arbitrary filesystem corruption would be very interesting.
I assume unprivileged and hostile users because if you trusted the real root inside of your container this would not be an issue.
Eric
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