Messages in this thread | | | Date | Mon, 2 Aug 2004 15:56:16 +0200 | From | Jens Axboe <> | Subject | Re: ide-cd problems |
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On Mon, Aug 02 2004, tabris wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On Sunday 01 August 2004 11:57 am, Jens Axboe wrote: > > On Sun, Aug 01 2004, Alexander E. Patrakov wrote: > > > Zinx Verituse wrote: > > > >I don't believe command filtering is neccessary, since all of the > > > >ide-cd ioctls are still there (ioctls that allow playing, reading, > > > > etc) Only the SG_IO ioctl itself would have to be checked (i.e., > > > > not each individual command available with SG_IO, just the > > > > overall ioctl itself, categorizing all of SG_IO more or less as > > > > raw IO. If this isn't doable with the current design, then the > > > > ide-cd interface should at least be very conspicuously documented > > > > as being extremely insecure as far as "read" access is concerned, > > > > as I know I wouldn't expect users to be able to overwrite my > > > > drive's firmware simply by granting the read access. > > > > > > Remember that it is still possible to write CDs through ide-cd in > > > 2.4.x using some pre-alpha code in cdrecord: > > > > > > cdrecord dev=ATAPI:1,1,0 image.iso > > > > (don't trim cc lists on linux-kernel!) > > > > Don't ever use that interface, period. It's not just the cdrecord > > code that may be alpha (I doubt it matters, it's easy to use), the > > interface it uses is not worth the lines of code it occupies. > Then we have a severe disagreement between the cdrecord code (or at > least the runtime warnings) and the Linux-Kernel IDE folks. > specifically, these lines, while running with cdrecord dev=/dev/cdrom > > scsidev: '/dev/cdrom' > devname: '/dev/cdrom' > scsibus: -2 target: -2 lun: -2 > Warning: Open by 'devname' is unintentional and not supported.
Kernel and cdrecord disagreement, news at 11.
> I've attached two logs, one using the ATAPI interface, one using > your suggested interface. Frankly, both have rather nasty > warnings on them, and one gets to wondering what the cdrecord > authors want... > > Maybe we should be cc:ing the authors of cdrecord as well?
I appreciate the good intentions, but perhaps you should research a bit of background on this before going over board here. Don't think it hasn't been suggested to Joerg before to kill that message.
Look at the errors as well - one is about the transport used:
> devname: 'ATAPI' > scsibus: 0 target: 0 lun: 0 > Warning: Using ATA Packet interface. > Warning: The related libscg interface code is in pre alpha. > Warning: There may be fatal problems. > SCSI buffer size: 64512
The other (for SG_IO)
> scsidev: '/dev/cdrom' > devname: '/dev/cdrom' > scsibus: -2 target: -2 lun: -2 > Warning: Open by 'devname' is unintentional and not supported.
just says that open-by-device name is unintentional, it doesn't give you warnings on the transport.
So in short (and repeating): don't use ATAPI (CDROM_SEND_PACKET), it sucks. Use SG_IO (which means using open-by-device, which works at least as well as the stupid faked ATAPI bus/id/lun crap and has the much better transport). Don't compare apples and oranges.
-- Jens Axboe
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