Messages in this thread | | | Date | Fri, 9 Aug 2013 14:54:49 -0700 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH 001/001] CHAR DRIVERS: a simple device to give daemons a /sys-like interface |
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On Wed, Aug 07, 2013 at 02:53:50PM -0700, Bob Smith wrote: > Greg Kroah-Hartman wrote: > >>The proxy device nodes are application specific and need to be > >>created as needed by applications. > > > >But applications do not have the permissions in a system to create > >device nodes. Nor should they need that permission. > > Agreed. But you need root permissions to install an application > and part of that installation can be setting up systemd files > that allocate resources at boot.
Do you have examples of those systemd files? Last I looked, they didn't have mknod permissions anymore, which is a good thing.
> Also, some applications start as root just so they can do this kind of > allocation. The app can (and should) drop root privileges when it > can.
You shouldn't require root for a new feature, that seems strange.
Also, namespaces aren't addressed at all, but that's a totally different issue...
> >>Allocation of minor numbers is an issue but that is an issue that > >>is separate from the proxy module itself. > >How is it separate, it seems tied directly to it as something that must > >be handled properly. > It can, but does not need to be handled in the kernel. It could > be handled in user space. > > > > >>> Also, no, setting the permissions like this is not ok for a real system, > >>> what is going to be in charge of setting the permissions on these random > >>> device nodes? > >> Again, compare proxy to a named pipe. It is up the application > >> writer to decide who gets read and write access to its proxy > >> nodes. > > > > Ok, but to do so, you have to have root permissions to start with, which > > is generally not going to happen on sane systems. Only allowing root > > access to this seems like a huge limitation. > > As noted above, yes, root has to set it up and set the permissions, > but this is hardly unusual, is it?
Yes it is, modern userspace does not create any device nodes anymore, please let's not regress on that point.
thanks,
greg k-h
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