[Devel] [patch] ext: prevent panic inside of containers

[Vasiliy Kulikov]

Hi Dmitry,

On Mon, Jan 24, 2011 at 15:40 +0300, Dmitry wrote:
> This is no sufficient to make loopdev safe.
> Loop devices inside container is very dangerous thing because 
> others filesystems

Aren't all other nonvirtual filesystems disabled inside of containers?
I see only ext2/3 in VE's /proc/filesystem, even ext4 is not available
here (but it's available on HN).

> (except ext234) has no well defined panic semantics,

Do you mean that they don't gracefully handle specially crafted
filesystems?  Agreed, but then with errors=panic ext2/3/4 is not safe too.

> BTW: in case of bad will frequent loop device corruption inside
> container result in massive dangerous messages which makes HW-node
> administrator's life a complete nightmare.

These log messages may be limited.  However, IMO they should be logged
at least once per VEID.

> That's why loop device is prohibited inside container by default.

If you protest against only loop case - the same can be achieved with
common block device forwarding: run mkfs.ext2 on it, manually corrupt
and enjoy.


Thanks,

-- 
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments