Quoting Pavel Emelyanov (xemul@xxxxxxxxxx): > Oren Laadan wrote: > > > > Serge E. Hallyn wrote: > >> Quoting Pavel Emelyanov (xemul@xxxxxxxxxx): > >>> Oren Laadan wrote: > >>>> Serge E. Hallyn wrote: > >>>>> Quoting Oren Laadan (orenl@xxxxxxxxxxxxxxx): > >>>>>> I hate to bring this again, but what if the admin in the container > >>>>>> mounts an external file system (eg. nfs, usb, loop mount from a file, > >>>>>> or via fuse), and that file system already has a device that we would > >>>>>> like to ban inside that container ? > >>>>> Miklos' user mount patches enforced that if !capable(CAP_MKNOD), > >>>>> then mnt->mnt_flags |= MNT_NODEV. So that's no problem. > >>>> Yes, that works to disallow all device files from a mounted file system. > >>>> > >>>> But it's a black and white thing: either they are all banned or allowed; > >>>> you can't have some devices allowed and others not, depending on type > >>>> A scenario where this may be useful is, for instance, if we some apps in > >>>> the container to execute withing a pre-made chroot (sub)tree within that > >>>> container. > >>>> > >>>>> But that's been pulled out of -mm! ? Crap. > >>>>> > >>>>>> Since anyway we will have to keep a white- (or black-) list of devices > >>>>>> that are permitted in a container, and that list may change even change > >>>>>> per container -- why not enforce the access control at the VFS layer ? > >>>>>> It's safer in the long run. > >>>>> By that you mean more along the lines of Pavel's patch than my whitelist > >>>>> LSM, or you actually mean Tetsuo's filesystem (i assume you don't mean that > >>>>> by 'vfs layer' :), or something different entirely? > >>>> :) > >>>> > >>>> By 'vfs' I mean at open() time, and not at mount(), or mknod() time. > >>>> Either yours or Pavel's; I tend to prefer not to use LSM as it may > >>>> collide with future security modules. > >>> Oren, AFAIS you've seen my patches for device access controller, right? > > > > If you mean this one: > > http://openvz.org/pipermail/devel/2007-September/007647.html > > then ack :) > > Great! Thanks. > > >>> Maybe we can revisit the issue then and try to come to agreement on what > >>> kind of model and implementation we all want? > >> That would be great, Pavel. I do prefer your solution over my LSM, so > >> if we can get an elegant block device control right in the vfs code that > >> would be my preference. > > > > I concur. > > > > So it seems to me that we are all in favor of the model where open() > > of a device will consult a black/white-list. Also, we are all in favor > > of a non-LSM implementation, Pavel's code being a good example. > > Thank you, Oren and Serge! I will revisit this issue then, but > I have a vacation the next week and, after this, we have a New > Year and Christmas holidays in Russia. So I will be able to go > on with it only after the 7th January :( Hope this is OK for you. > > Besides, Andrew told that he would pay little attention to new > features till the 2.6.24 release, so I'm afraid we won't have this > even in -mm in the nearest months :( > > Thanks, > Pavel Cool, let me know any way I can help when you get started. thanks, -serge - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
