Messages in this thread |  | | Date | Sat, 31 Jul 2004 13:27:41 -0500 | From | Zinx Verituse <> | Subject | Re: ide-cd problems |
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On Sat, Jul 31, 2004 at 05:36:10PM +0200, Jens Axboe wrote: > On Fri, Jul 30 2004, Zinx Verituse wrote: > > I'm going to bump this topic a bit, since it's been a while.. > > There are still some issues with ide-cd's SG_IO, listed from > > most important as percieved by me to least: > > > > * Read-only access grants you the ability to write/blank media in the drive > > * (with above) You can open the device only in read-only mode. > > That's by design. Search linux-scsi or this list for why that is so.
The only thing I can find on the linux-scsi list is refering to sg devices, which are on a different device node from the non-generic device. This means you can still allow users read access to the disk without allowing them to send random commands to the disk -- this isn't currently possible with the IDE interface, since the device with generic access is the same as the one with the original read/cdrom commands access.
As it is, it's impossible grant users read-only access to an IDE cd-rom without allowing them to do things like replacing the firmware with a malicious/non-working one.
Generic access allowing such things is fine; but only if we can grant non-generic access without granting generic access.
> > > * You can't open the device unless there is media in the drive > > False, you use O_NONBLOCK.
Thanks, I didn't know about this one -- works great :)
> [snip stuff about scatter gather/manual dma] > > -- > Jens Axboe
-- Zinx Verituse http://zinx.xmms.org/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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