Re: [bug] 2.6.8: CDROM_SEND_PACKET ioctls failing as non-root on ide scsi drives

[Sean Neakums]

Luke Kenneth Casson Leighton <lkcl@xxxxxxxx> writes:

> kernel 2.6.8.  ioctl ("/dev/hdc", CDROM_SEND_PACKET, cmd)
>
> commands that are failing as non-root, even when permission is granted
> rwxrwxrwx to /dev/hdc, are, according to some debug info added to k3b:
>
> 	GET CONFIGURATION (46)
> 	error code: 0
> 	sense key: NO SENSE (2)
> 	asc: 0
> 	ascq: 0
>
> and:
>
> 	MODE SELECT (55)
> 	error code: 0
> 	sense key: NO SENSE (2)
> 	asc: 0
> 	ascq: 0
>
> the result is that k3b cannot determine that the drive exists, therefore
> it cannot use it even though cdrecord might actually work.
>
>
> as root, the following errors occur:
>
> 	MODE SELECT (46)
> 	errorcode: 70
> 	sense key: ILLEGAL REQUEST (5)
> 	asc: 26
> 	ascq: 0
>
> 	READ DVD STRUCTURE (ad)
> 	errorcode: 70
> 	sense key: NOT READY (2)
> 	asc: 3a
> 	ascq: 0
>
> presumably it can be concluded that the GET CONFIGURATION ioctl command
> is the one at fault.
>
> ... what gives?

CDROM_SEND_PACKET calls down to sg_io, which calls verify_command,
which will not permit anyone but root to use any unrecognised
commands.  GET CONFIGURATION does not seems to be one of those
recognised.  This check for unrecognised commands is a fairly recent
addition, IIRC.
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