Re: group video?

[Kenneth MacDonald <kenny@holyrood.ed.ac.uk>]

>>>>> "Lee" == Lee Bradshaw <lee@sectionIV.com> writes:

    Lee> Your posting made me wonder about the proper setup for the
    Lee> scsi generic devices.

    Lee> I have /dev/scd0 as a read-only CDROM, and /dev/scd1 as a cd
    Lee> writer.

If I recall, cd writing applications use the generic scsi devcies too.

    Lee> To rip CD's, cdparanoia needs access to the scsi generic
    Lee> devices. I tried permissions of:

[deletia]

    Lee> If I change the permissions on all the sg devices to group
    Lee> rw, I can run cdparanoia as a normal user in group cdrom. But
    Lee> I don't want to have all the scsi generic devices writeable
    Lee> by everyone in group cdrom.  And setting just the correct
    Lee> scsi devices to be writeable is dangerous, because modifying
    Lee> the devices on the scsi bus may cause the generic devices to
    Lee> point to different physical devices. That is, if I make the
    Lee> scsi generic device for the cdrom writeable, it may be the
    Lee> scsi generic device for a hard drive after some hardware
    Lee> modifications.

Yes, I thought this too.  And yes, it does concern me, especially as I
plug in external SCSI devices from time to time.  The safest thing
would be to have a script run at system boot that sets the permissions
on the appropriate sg files depending on the contents of
/proc/scsi/blah-blah-blah.  In the meantime, I'll be trying to make
sure I have all my internal devices on low SCSI ids and leave the high
ones for external devices.

    Lee> Does anyone see a problem with my /dev setup? Does cdparanoia
    Lee> really need write permission to a cdrom drive in order to
    Lee> find it?

Yes, it seems it does.  Remember, the sg* devices allow the program to
send commands to particular devices on the SCSI bus, so therefore they
must be writable by whoever's running the application.

Kenny.

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ADML Support, EUCS, The University of Edinburgh.