Re: DoS with unprivileged mounts

[Andy Lutomirski]

On 08/14/2013 10:42 AM, Miklos Szeredi wrote:
> There's a simple and effective way to prevent unlink(2) and rename(2)
> from operating on any file or directory by simply mounting something
> on it.  In any mount instance in any namespace.
> 
> Was this considered in the unprivileged mount design?
> 
> The solution is also theoretically simple: mounts in unpriv namespaces
> are marked "volatile" and are dissolved on an unlink type operation.

I'd actually prefer the reverse: unprivileged mounts don't prevent
unlink and rename.  If the dentry goes away, then the mount could still
exist, sans underlying file.  (This is already supported on network
filesystems.)

--Andy
--
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/