What changes my device permissions

What changes my device permissions

[Christoph Pleger]

Hello,

I have been using pam_devperm for a long time. If pam_devperm is
configured like I did, it causes that, when a user logs in on :0, the
permissions and ownerships of some device nodes in /dev are changed so
that the device file belongs to the user on :0 and has permissions
600. Now, I upgraded to a new OS version and found, that after logging
in on :0, some of the device file have permissions 660, not 600. It
seems that, after pam_devperm has changed the permissions to 600, some
other process resets them to 660.

How can I find out what is changing the device permissions?

Regards
  Christoph    

Re: What changes my device permissions

[Michal Nazarewicz]

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Christoph Pleger <Christoph.Pleger@cs.tu-dortmund.de> writes:

> Hello,
>
> I have been using pam_devperm for a long time. If pam_devperm is
> configured like I did, it causes that, when a user logs in on :0, the
> permissions and ownerships of some device nodes in /dev are changed so
> that the device file belongs to the user on :0 and has permissions
> 600. Now, I upgraded to a new OS version and found, that after logging
> in on :0, some of the device file have permissions 660, not 600. It
> seems that, after pam_devperm has changed the permissions to 600, some
> other process resets them to 660.
>
> How can I find out what is changing the device permissions?

There's the hard way: use process accounting.

There's also easier way which *might* work: provide a shell wrapper for
chmod, like so:

$ : >/tmp/chmod-log && chmod 666 /tmp/chmod-log
$ cd /usr/bin
$ mv chmod chmod-
$ cat >chmod <<EOF
#!/bin/sh
echo "$@" >>/tmp/log
/usr/bin/chmod- "$@"
EOD

-- 
Best regards,                                         _     _
 .o. | Liege of Serenly Enlightened Majesty of      o' \,=./ `o
 ..o | Computer Science,  Michal "mina86" Nazarewicz   (o o)
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Re: What changes my device permissions

[Christoph Pleger]

Hello,

On Tue, 08 Jun 2010 13:50:30 +0200
Michal Nazarewicz <mina86@tlen.pl> wrote:

> There's the hard way: use process accounting.
> 
> There's also easier way which *might* work: provide a shell wrapper
> for chmod, like so:

Unfortunately, these solutions did not help.

In the meanwhile, I found out that my original problem (wrong
permissions of devices, for example /dev/sr0) can be solved in two ways:

1. Deinstall consolekit
2. Use another display manager than gdm

But I am looking for a solution that works with every display manager,
and I need consolekit to solve other problems.

Regards
  Christoph