Re: Re: [PATCH] udev callout for reading filesystem labels

[Kay Sievers <kay.sievers@vrfy.org>]

On Fri, May 07, 2004 at 12:44:01AM +0200, Arnd Bergmann wrote:
> Kay Sievers <kay.sievers@vrfy.org> schrieb am 06.05.2004, 22:18:41:
> > On Thu, May 06, 2004 at 11:30:23AM +0200, Arnd Bergmann wrote:
> > > On Thursday 29 April 2004 23:04, Kay Sievers wrote:
> > 
> > Sure, we can do this. How much code do we need, for the parsing?
> 
> The attachment contains the code from the linux kernel that does
> the equivalent, somewhat adapted to user interfaces (but probably
> not functional due to lack of sleep). I'll try to do a working
> patch tomorrow.
> 
> What would you do to find out the disk minor when udev is
> called for a partition of the disk? Is this handled by udev
> already or do we need additional logic in the callout program?

Hmm, we can take libsysfs's get_parent() for the partition, to get the main
device.


> > > This looks like a malicious user can easily prevent it from working
> > > by creating files in /tmp. You might need to use something similar
> > > to tmpfile(3) here.
> > 
> > Hmm, I really like to be able to compile with klibc and it doesn't
> > support tmpfile(). What about simply unlinking it, before creating the node?
> 
> Well, I did not mean tmpfile itself, just something similar enough. 
> Unlinking the file certainly avoids the security problem, but it
> sounds a little rude. Are you sure there is no race when udev is
> called multiple times for the same device node and we unlink before
> the other udev opens the node?

We may include the PID in the filename?

thanks,
Kay


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