Re: [gentoo-dev] useless set*id binaries

[Samuli Suominen]

On 01/28/2012 10:32 AM, Michał Górny wrote:
> On Sat, 28 Jan 2012 03:07:45 +0200
> Samuli Suominen<ssuominen@g.o>  wrote:
>
>> On 01/28/2012 02:41 AM, Mike Frysinger wrote:
>>> On Friday 27 January 2012 19:18:07 Samuli Suominen wrote:
>>>> On 01/28/2012 02:14 AM, Mike Frysinger wrote:
>>>>> along these lines, why is cdrtools set*id ?  if we have a "cdrom"
>>>>> group, and we assign our cdroms/dvdroms to that group, then we
>>>>> already have access control in place and can skip the set*id.
>>>>
>>>> cdrtools can't probe the drives without the binary being setuid,
>>>> or the user belonging to the 'disk' group (and even that is not
>>>> enough in some cases if the permissions vary)
>>>
>>> the drives are owned by the "cdrom" group and have group +rw.  so
>>> if the user is in the "cdrom" group, why can't they probe the
>>> drives ?
>>>
>>> "disk" owns the non-removable hard drives.
>>>
>>> $ ls -l /dev/sr0 /dev/sg0 /dev/sg6
>>> crw-rw---- 1 root disk  21, 0 Jan  6 23:07 /dev/sg0
>>> crw-rw---- 1 root cdrom 21, 6 Jan  6 23:07 /dev/sg6
>>> brw-rw---- 1 root cdrom 11, 0 Jan 17 22:28 /dev/sr0
>>> -mike
>>
>> i dont know why, but it does probe also non-removable disks... it
>> probes per bus, iirc
>>
>> you can try it easily yourself:
>>
>> ssuominen@null ~ $ cdrecord -scanbus
>
> Does user actually need to be able to do this? Doesn't passing dev=...
> directly work?
>

It will work if you specify it by hand. But how do you know without 
using -scanbus what to specify?

Also, burning frontends, such as xfburn, rely on this functionality to 
automatically find the burner when USE="udev" is disabled.

And if I don't remember wrong, k3b also uses it as fallback method.