Re: devfs again, (was RE: USB device allocation)

Horst von Brand (vonbrand@inf.utfsm.cl)
Thu, 07 Oct 1999 15:00:44 -0400

"Jakma, Paul" <Paul.Jakma@compaq.com> said:
> > > the permissions in a config file, exact syntax i forget,
> > but something like:
> > >
> > > /dev/sd/c0b1t3u0 PERM root.disk 664
> > > /dev/sd PERM root.disk 660
> > >
> > > etc.. and all your SCSI disks will automatically get these
> > perm's when
> > > they're created, except for disk bus1id3, which get's
> > special perms's.. etc.
> > >
> > > now that's nice. Much easier to admin, which leads to
> > better security, etc.

This is _horrible_. Suddenly there are files whose attributes aren't fixed
by chmod(1)/chown(1), but by a magic file.

Again. The way Unix is designed, permanent information about files resides
in the filesystem. Another basic Unix design premise is that devices are
files. So their attributes reside in the filesystem. Anything else breaks
much ("tar cf dev.tar /dev", ..., "tar xf dev.tar /dev" doesn't work
anymore (but it looks like it does!); can't dump/restore /dev; ...). It
might also have _very_ serious security implications (what if the magic
devfs.conf file goes missing, or is clobbered?)

-- 
Dr. Horst H. von Brand                       mailto:vonbrand@inf.utfsm.cl
Departamento de Informatica                     Fono: +56 32 654431
Universidad Tecnica Federico Santa Maria              +56 32 654239
Casilla 110-V, Valparaiso, Chile                Fax:  +56 32 797513


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