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

[Piotr Karbowski]

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.
>
>
>> the ENV=regex; thingy is nice, can I combine multiple env vars there? Like
>>
>>          SUBSYSTEM=net;DEVPATH=/devices/virtual/net/.*;.* root:root 600 !
>
> Yes, multiple eenvvars can be checked like the above.
>

Denys, please check 'busybox >=1.21.0 segfaults.' thread, that's 
propably the rootcase of /dev/snd/* issue, kind of better to keep it in 
another thread as this does not really fit anymore. ;-)

-- Piotr.