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Annoying cdrw permissions problem.

Annoying problem with my cdrw drive: I can never get it to keep its permissions. Everytime I put a cd in, I have at chmod a+r /dev/hdc. not sure why... This only started happening when I upgraded to kernel 2.6.10. I think it has something to do with udev, not sure...

I have this:

Code:

# permissions for IDE CD devices

BUS="ide", KERNEL="*[!0-9]", PROGRAM="/bin/cat /proc/ide/%k/media", RESULT="cdrom*", NAME="%k", GROUP="cdrom", MODE="0666"

BUS="ide", KERNEL="*[!0-9]", PROGRAM="/bin/cat /proc/ide/%k/media", RESULT="cdrw*", NAME="%k", GROUP="cdrom", MODE="0666"

in my /etc/udev/rules.d/udev.rules file.

Not playing with udev yet, but I'm fairly sure I remember reading that there is also another udev-specific file involved.

Also, your system-wide umask (man umask) may still have something to do with it.

But from your 'code', it might be udev itself, so may I suggest you search here and at www.google.com/linux for any possible reports/fixes?
Your search term should probably be in the advanced box as 'all words' needing udev and cd.

hth,

I haven't yet played with udev much but your problem has sparked in me an interest with it, so I'm looking into it.

Do you have any files in /etc/udev/permissions.d/ ? I am running Fedora Core 3 with kernel 2.6.9 & this is were the files that define the udev device permissions reside in FC3.
If you are defining the perms in both /etc/udev/rules.d/udev.rules & /etc/udev/permissions.d/*.permissions then there might be a fight between these two as to what perms to use.

If you do have any files in /etc/udev/permissions.d/, post their contents & we'll try to get to the bottom of this.

Also, run:

ls -R /etc/udev/

& post results.

$ ls -R /etc/udev/
/etc/udev/:
permissions.d/ rules.d/ scripts/ udev.conf

/etc/udev/permissions.d:
udev.permissions udev.permissions~

/etc/udev/rules.d:
10-local.rules compat.rules.unsupported udev.rules
10-local.rules~ devfs.rules.unsupported udev.rules~

/etc/udev/scripts:
floppy-extra-devs.sh* ide-devfs.sh* make_extra_nodes.sh* scsi-devfs.sh*

...is what I got.

Also, here's the contents of /etc/udev/permissions.d/udev.permissions :
(I think you'll find the only interesting section is "Optical Devices")
So, yeah it looks like I may be defining the permissions for the drive twice, but so? I define them the same way: 0666

Code:



# console devices

console:root:tty:0600

tty:root:tty:0666

tty[0-9][0-9]*:root:tty:0660

vc/[0-9]*:root:tty:0660



# pty devices

#  Set this to 0660 if you only want users belonging to tty group

#  to be able to allocate PTYs

ptmx:root:tty:0666

pty[p-za-e][0-9a-f]*:root:tty:0660

tty[p-za-e][0-9a-f]*:root:tty:0660

pty/m*:root:tty:0660

vc/s*:root:tty:0660



# serial+dialup devices

ttyS*:root:uucp:0660

tts/[0-9]*:root:uucp:0660

ttyUSB*:root:uucp:0660

tts/USB[0-9]*:root:uucp:0660

ppp:root:uucp:0660

ippp*:root:tty:0660

isdn*:root:tty:0660

isdnctrl*:root:tty:0660

capi*:root:tty:0660

dcbri*:root:tty:0660

ircomm*:root:tty:0660



# vc devices

vcs:root:tty:0620

vcs[0-9]*:root:tty:0620

vcsa:root:tty:0620

vcsa[0-9]*:root:tty:0620

vcc/*:root:tty:0620



# memory devices

random:root:root:0644

urandom:root:root:0644

mem:root:kmem:0640

kmem:root:kmem:0640

port:root:kmem:0640

full:root:root:0666

null:root:root:0666

zero:root:root:0666



# misc devices

misc/nvram:root:root:0660

misc/rtc:root:root:0664

misc/psaux:root:sys:0660



# floppy devices

floppy/[0-3]:root:floppy:0666



# audio devices

dsp*:root:audio:0662

audio*:root:audio:0662

midi*:root:audio:0662

mixer*:root:audio:0666

sequencer*:root:audio:0662

sound/*:root:audio:0662

snd/control*:root:audio:0666

snd/midi*:root:audio:0666

snd/pcm*p:root:audio:0666

snd/seq:root:audio:0666

snd/timer:root:audio:0666

snd/hw*:root:audio:0662

snd/pcm*c:root:audio:0662

beep:root:audio:0664

admm*:root:audio:0662

adsp*:root:audio:0662

aload*:root:audio:0662

amidi*:root:audio:0662

dmfm*:root:audio:0662

dmmidi*:root:audio:0662

sndstat:root:audio:0662



# optical devices

sr*:root:cdrom:660

scd*:root:cdrom:660

pcd*:root:cdrom:0660

cdrom*:root:cdrom:0666

cdrw*:root:cdrom:0666

dvd:root:cdrom:0660

rdvd:root:cdrom:0660

cdroms/*:root:cdrom:0666



# pilot/palm devices

pilot:root:uucp:0660



# jaz devices

jaz*:root:disk:0660



# zip devices

pocketzip*:root:disk:0660

zip*:root:disk:0660



# ls120 devices

ls120:root:disk:0660

ls120*:root:disk:0660



# lp devices

lp*:root:lp:0660

parport*:root:lp:0660

irlpt*:root:lp:0660

usblp*:root:lp:0660

usb/lp*:root:lp:0660



# scanner devices

scanner:root:root:0600

usb/scanner*:root:root:0600



# camera devices

camera*:root:root:0600

usb/dc2xx*:root:root:0600

usb/mdc800*:root:root:0600



# raw devices

ram*:root:disk:660

raw/*:root:disk:660



# disk devices

hd*:root:disk:660

sd*:root:disk:660

dasd*:root:disk:660

ataraid*:root:disk:660

loop*:root:disk:660

md*:root:disk:660

ide/*/*/*/*/*:root:disk:660

discs/*/*:root:disk:660

loop/*:root:disk:660

md/*:root:disk:660



# tape devices

ht*:root:sys:0660

nht*:root:sys:0660

pt[0-9]*:root:sys:0660

npt*:root:sys:0660

st*:root:sys:0660

nst*:root:sys:0660



# dm devices

dm-*:root:root:0640



# memstick devices

memstick*:root:root:0600



# flash devices

flash*:root:root:0600



# diskonkey devices

diskonkey*:root:disk:0660



# rem_ide devices

microdrive*:root:disk:0660



# fb devices

fb:root:root:0600

fb[0-9]*:root:root:0600

fb/*:root:root:0600



# kbd devices

kbd:root:root:0644



# joystick devices

js[0-9]*:root:root:0644

djs[0-9]*:root:root:0644



# video4linux devices

video*:root:video:0660

radio*:root:video:0660

winradio*:root:video:0660

vtx*:root:video:0660

vbi*:root:video:0660

video/*:root:video:0660

vttuner:root:video:0660

v4l/*:root:video:0660



# input devices

input/event*:root:root:600

input/ts*:root:root:600

input/*:root:root:644



# Sony Vaio Jogdial sonypi device

sonypi:root:root:0666



# gpm devices

gpmctl:root:root:0700



# dri devices

nvidia*:root:video:0666

3dfx*:root:video:0660

dri/*:root:video:0660



# mainboard devices

apm_bios:root:root:0600



# scsi devices

sg*:root:disk:0660

pg*:root:disk:0660

cdwriter:root:disk:0666



# usb devices

usb/dabusb*:root:sys:0660

usb/mdc800*:root:sys:0660

usb/rio500:root:sys:0660

usb/legousbtower*:root:usb:0660



sgi_fetchop:root:root:666

iseries/vcd*:root:disk:660

iseries/vd*:root:disk:660

I just remembered!!!
I had the same trouble when I first went to the 2.6 kernel.
The way you are supposed to do this now is to add any user that wants cdrom access to the "disk" group.

As root:

usermod -G disk <user_name>

You might also want to undo any changes you made to your udev files.

hey fuzzyash: didn't work. oh and by the way, don't use KUser to change user/group permissions... it will only end in pain!

what changes in the udev files should I undo? I don't even remember the order I made them in :(

Quote:

The way you are supposed to do this now is to add any user that wants cdrom access to the "disk" group.

As root:

usermod -G disk <user_name>

This gives the user unlimited write access to all hard disk devices because they are also owned by group "disk".

I use this configuration file with a couple of additions at the end:

Code:

BUS="ide", ID="1.0", SYMLINK="cdrom"

BUS="ide", ID="1.0", SYMLINK="dvd"

BUS="ide", ID="1.0", GROUP="audio", MODE="660"

The group could be something like "cdburner" but I think it's better to have just one group for all multimedia stuff.

Lord Zoltar:
I was having a problem with my cdrom and dvd drives when I upgraded to the 2.6.11.9 kernel. I found the udev would change the links in /dev everytime I booted up. I had /dev set like this:

Code:

cdrom -> hdc

dvd -> hdd

But everytime I rebooted it would look like this:

Code:

cdrom -> hdd

dvd -> hdd

So after having to physically reset the links and permissions in /dev after every boot, I just uninstalled udev. Haven't had any problems since. One of things I like most about Slackware. Being able to take something out and not having the machine crash on you.

Quote:

I just uninstalled udev. Haven't had any problems since.

Simply uninstalling udev, in my opinion, is not a good idea unless you either NEVER want to modify your systems hardware again, or you're a Linux EXPERT!

Problems arise with simply uninstalling udev. Lets face it, most average users out there running Linux at home are gonna want to add a hard drive, plug in a USB memory stick or mp3 player or something of that description at some stage. udev was specifically developed to help make adding devices to the system much simpler & faster, making Linux more user friendly for those who want to use a reliable OS, but don't want to become an absolute expert. All they want is for their computer to do what they want, without having to go through a steep learning curve to what most would consider an easy task, like simply downloading the pics off their digital camera for example.
So the problem with uninstalling udev is that if you ever want to add or remove devices to or from your system, then you will need to go to a great deal more trouble to get them to work. This might be alright for those of us who enjoy learning all their is to know about every task that they preform, but for most users, this is a pain in the arse!

Alright, back to the problem...

A couple of posts ago I said:

Quote:

add any user that wants cdrom access to the "disk" group.

& Lord Zoltar you said that this did not work. I am running Fedora Core 3 & "disk" is the group that all the disks are grouped under by Fedora. Your disk group, if any, is most likely different being that you are running Slackware 10.0.

Run:

Code:

ls -l /dev/hdc

& post results.

Harmaa Kettu, you obviously know more about udev & how it works than I do. Could you please explain your answer, in other words, why this works? Could you also please post a link to where to find a good tutorial site on udev & how to configure it, if you know of one of course!

Thanks!