"mdev: remove undocumented subsystem/devname matching hack" disaster.

Tue Apr 2 11:58:59 UTC 2013

On 03/29/2013 02:58 PM, Denys Vlasenko wrote:
> On Thu, Mar 28, 2013 at 11:14 AM, Piotr Karbowski
> <piotr.karbowski at gmail.com> wrote:
>> On 03/04/2013 03:47 AM, Denys Vlasenko wrote:
>>>
>>> On Friday 01 March 2013 21:19, Piotr Karbowski wrote:
>>>>
>>>> log attached from running mdev with both patches applied onto 1.21.0.
>
> mdev[674]: 21.569605 waiting for ''
> mdev[675]: 21.570325 waiting for ''
> mdev[676]: 21.571087 waiting for ''
> mdev[677]: 21.571604 waiting for ''
> mdev[678]: 21.572118 waiting for ''
> mdev[679]: 21.572529 waiting for ''
>
> This message can only be shown if /dev/mdev.seq exists but contains
> nothing (zero-length file). Not even a newline.
> Please change your init script to create  /dev/mdev.seq which contains
> a single newline. Say, by using "echo >/dev/mdev.seq", because
> current code will only consider _this exact file contents_
> as the seed seqfile.
>
>> I've tested latest busybox git code, the patch seems to be already commited
>> there. I did the test without the old debuging patches you sent me.
>>
>> Mdev.log attached, /dev/snd/* still have wrong permissions.
>>
>>          crw-rw---- 1 root root  116,  5 Mar 28 11:05 controlC0
>>          crw-rw---- 1 root audio 226, 64 Mar 28 11:05 controlD64
>>          crw-rw---- 1 root root  116,  4 Mar 28 11:05 hwC0D0
>>          crw-rw---- 1 root root  116,  3 Mar 28 11:05 pcmC0D0c
>>          crw-rw---- 1 root root  116,  2 Mar 28 11:05 pcmC0D0p
>>          crw-rw---- 1 root root  116, 33 Mar 28 11:05 timer
>
> Here is the part of the log where /dev/controlC0 is created:
>
> mdev[729]: 25.398178 exiting
> ^^^^^^^^^^^^^^^^ prev mdev exits
> mdev[730]: 25.399677 ACTION:add SUBSYSTEM:sound DEVNAME:snd/controlC0
> DEVPATH:/devices/pci0000:00/0000:00:1b.0/sound/card0/controlC0
> mdev[730]: dev 116,5
> mdev[730]: rule matched, line 111
> mdev[730]: mknod snd/controlC0 (116,5) 20660 0:0
> ^^^^^^^^^^^^^^^^^^^^^ mdev uses uid:gid 0:0
> mdev[730]: running: /opt/mdev/helpers/catch-all
> mdev[730]: 25.412042 exiting
>
> So, it looks like uid:gid 0:0 is set by mdev, not by something else.
> You  said that you are using this rule:
>
>          pcm.*           root:audio 660 =snd/
>          control.*       root:audio 660 =snd/
>          midi.*          root:audio 660 =snd/
>          seq             root:audio 660 =snd/
>          timer           root:audio 660 =snd/
>
> Unfortunately current code has no logging in parsing code where
> it parses "user:group". The code is:
>
>                  /* 2nd field: uid:gid - device ownership */
>                  if (get_uidgid(&G.cur_rule.ugid, tokens[1],
> /*allow_numeric:*/ 1) == 0) {
>                          bb_error_msg("unknown user/group '%s' on line
> %d", tokens[1], G.parser->lineno);
>                          goto next_rule;
>                  }
>
> Please add this line after this block of code (after the line which
> has just "}"):
>
> bb_error_msg("line:%d str:'%s' gid:%d", G.parser->lineno, tokens[1],
> G.cur_rule.ugid.gid);
>
> Then recompile, rerun the test, send me the new log,
> and your mdev.conf too.

Okey, let's continue here.

FYI, the alsa is compiled as modules, so first mdev -s does not pick 
them up, later in init script there is coldplug part, after setting mdev 
as hotplug agent

	find /sys -name 'modalias' -type f -exec cat '{}' + | sort -u | xargs 
modprobe -b -a 2>/dev/null

Running mdev -s after it does set correct permissions in /dev/snd/.
Also I am aware of the -net/ in config, its leftover from older version 
and not yet ported.

The mdev.log is regular gzip file but because of gmail I added .bin sufix.

-- Piotr.

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# mdev-like-a-boss

# Syntax:
# [-]devicename_regex user:group mode [>|=path] [@|$|*cmd args...]
#
# =: move, >: move and create a symlink
# @|$|*: run $cmd on delete, @cmd on create, *cmd on both

# support module loading on hotplug
$MODALIAS=.*	root:root 660 @modprobe "$MODALIAS"

# null may already exist; therefore ownership has to be changed with command
null		root:root 666 @chmod 666 $MDEV
zero		root:root 666
full		root:root 666
random		root:root 444
urandom		root:root 444
hwrandom	root:root 444
grsec		root:root 660

# Kernel-based Virtual Machine.
kvm		root:kvm 660

kmem		root:root 640
mem		root:root 640
port		root:root 640
# console may already exist; therefore ownership has to be changed with command
console		root:tty 600 @chmod 600 $MDEV
ptmx		root:tty 666
pty.*		root:tty 660

# Typical devices

tty		root:tty 666
tty[0-9]*	root:tty 660
vcsa*[0-9]*	root:tty 660
ttyS[0-9]*	root:uucp 660

# block devices
ram([0-9]*)		root:disk 660 >rd/%1
loop([0-9]+)	root:disk 660 >loop/%1
sd[a-z].*		root:disk 660 */opt/mdev/helpers/storage-device
vd[a-z].*		root:disk 660 */opt/mdev/helpers/storage-device
hd[a-z].*		root:disk 660 */opt/mdev/helpers/storage-device
md[0-9]*		root:disk 660 */opt/mdev/helpers/storage-device
dm-[0-9]*		root:disk 660 */opt/mdev/helpers/storage-device
mmcblk[0-9].*	root:disk 660 */opt/mdev/helpers/storage-device
sr[0-9]*		root:cdrom 660 @ln -sf $MDEV cdrom
fd[0-9]*		root:floppy 660

# Run settle-nics every time new NIC appear.
# If you don't want to auto-populate /etc/mactab with NICs, run 'settle-nis' without '--write-mactab' param.
-net/.*		root:root 600 @/opt/mdev/helpers/settle-nics --write-mactab
tun[0-9]*	root:kvm 660 =net/
tap[0-9]*	root:root 600 =net/

# alsa sound devices and audio stuff
pcm.*		root:audio 660 =snd/
control.*	root:audio 660 =snd/
midi.*		root:audio 660 =snd/
seq		root:audio 660 =snd/
timer		root:audio 660 =snd/

adsp		root:audio 660 >sound/
audio		root:audio 660 >sound/
dsp		root:audio 660 >sound/
mixer		root:audio 660 >sound/
sequencer.*	root:audio 660 >sound/

# raid controllers
cciss!(.*)	root:disk 660 =cciss/%1
ida!(.*)	root:disk 660 =ida/%1
rd!(.*)		root:disk 660 =rd/%1

fuse		root:root 666

card[0-9]	root:video 660 =dri/

agpgart		root:root 660 >misc/
psaux		root:root 660 >misc/
rtc		root:root 664 >misc/

# input stuff
event[0-9]+	root:root 640 =input/
mice		root:root 640 =input/
mouse[0-9]	root:root 640 =input/
ts[0-9]		root:root 600 =input/

# v4l stuff
vbi[0-9]	root:video 660 >v4l/
video[0-9]	root:video 660 >v4l/

# dvb stuff
dvb.*		root:video 660

# Don't create old usbdev* devices.
usbdev[0-9].[0-9]* root:root 660 !

# Stop creating x:x:x:x which looks like /dev/dm-*
[0-9]+\:[0-9]+\:[0-9]+\:[0-9]+ root:root 660 !

# /dev/cpu support.
microcode		root:root 600 =cpu/
cpu([0-9]+)		root:root 600 =cpu/%1/cpuid
msr([0-9]+)		root:root 600 =cpu/%1/msr

# Catch-all other devices, the script will
# populate /dev/bus/usb etc...
.* root:root 660 */opt/mdev/helpers/catch-all
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