Messages in this thread | | | Date | Mon, 12 Jan 1998 08:08:33 +1100 | From | Richard Gooch <> | Subject | Re: devfs initial permissions |
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Andreas Jellinghaus writes: > >People are devising all kinds of schemes for sensible devfs initial > >defalut values. In particular, one person had a table of uids and gids > >compiled into the kernel. I think this is a Bad Thing. > > >Using gid 0 is not a horrible idea, but I think that using any uid or gid > >*except* 0 is a Bad Thing. > > i agree. > > >I'd prefer having a default mode of 000, to make it clear that you really > >have to make a decision about the permissions, and the kernel isn't going > >to do it for you. > > i disagree. /dev/null should be always write and readable and /dev/zero > always readable. > > the device driver should suggest a permission using this table : > first 3 bits (suid, sgid, t) always 0 > all execute bits always 0 > owner read 1 if driver supports read > owner write 1 if driver supports write > global read 0 default > 1 read access will not give additional resources, > driver was designed to offer public read > (e.g. null zero random urandom) > global write 0 default > 1 write access will not give additional resource > driver was designed to offer public write > (e.g. null random urandowm) > user read 0 default > 1 if reading access will give resources, but not > compromisse system security > (audio, mouse and serial devices, but not disk > or /dev/kmem) > user write 0 default > 1 if write access will give resources, but not > compromisse system security > (audio, mouse and serial devices, but not disk > or /dev/kmem) > > summary : device drivers should give default permission. > give a permission for "group", if it makes sence to have a special group > on your system (e.g. "audio"), some privileged users in that group (e.g. > me) so they can access additional resources. > > this does not make sence for things like hard disks or /dev/kmem : > access to devices could be used to gain root status (in case of the root > hard disk or the kmem this should be easy).
So my system where the device driver provides a default mode,uid,gid does everything you want, easily. There's no need to invent new permission variable types. It's up to the driver writer to choose permissions.
Regards,
Richard....
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