Re: R: Linux kernel source archive vulnerable

Bill Davidsen
2006-09-14T22:59:49Z

> Chris
David Wagner wrote:
> Rene Scharfe wrote:
>> [details on how GNU tar works, snipped]
>
> Again, you miss my point. I already know how tar works, but that's not
> my point. Why is it that people are so unwilling to address the real
> issue here? Let's try a few facts:

Okay:
- you have been told told read the old posts on this topic
- you read but didn't understand
- the problem is YOU ARE DOING IT WRONG and untarring as root

The time to discuss where to put the umask was "back when," and I might
have agreed then, but now I can't see any justification to change,
because someone else would then have a problem. You want it to do
something else on your system, so do it. You shouldn't untar as root anyway.

You have not only beaten a dead horse, but dragged the carcass through
the streets.
>
> (a) The Linux kernel tar archive contains files with world-writeable
> permissions.
>
> (b) There is no need for those files to have world-writeable
> permissions. It doesn't serve any particular purpose. If the
> permissions in the tar archive were changed to be not world-writeable,
> no harm would be done.
>
> (c) Some users may get screwed over by virtue of the fact that those
> files are listed in the tar archive with world-writeable permissions.
> (Sure, if every user was an expert on "tar" and on security, then
> maybe no one would get screwed over. But in the real world, that's
> not the case.)
>
> (d) Consequently, the format of the Linux kernel tar archive is
> exposing some users to unnecessary riskis.
>
> (e) The Linux kernel folks could take a quick and easy step that
> would eliminate this risk. That step would involve storing the
> files in the tar archive with permissions that were more reasonable
> (not world-writeable would be a good start!). This step wouldn't
> hurt anyone. There's no downside.
>
> (f) Yet the Linux kernel folks refuse to take this step, and any
> time someone mentions that there is something the Linux kernel folks
> could do about the problem, someone tries to change the topic to
> something else (e.g., complaints about bugs in GNU tar, suggestions
> that the user should invoke tar with some other option, claims that
> this question has been addressed before, you name it).
>
> So why is it that the tar archive is structured this way? Why are
> the Linux kernel folks unnecessarily exposing their users to risk?
> What purpose, exactly, does it serve to have these files stored with
> world-writeable permissions?
>
> Folks on the Linux kernel mailing list seem to be reluctant to admit these
> facts forthrightly. The posts I've seen mostly seem to have little or
> no sympathy for users who get screwed over. The attitude seems to be:
> if you get screwed over, it's your fault and your problem. Why is that?
> If there is a simple step that Linux developers can take to eliminate
> this risk, why is there such reluctance to take it, and why is there
> such eagerness to point the finger at someone else?
>
> The way I see it, storing files in a tar archive with world-writeable
> permissions is senseless. Why do such a strange thing on purpose?
>
> It all seems thoroughly mysterious to me.

--
Bill Davidsen <davidsen@tmr.com>
Obscure bug of 2004: BASH BUFFER OVERFLOW - if bash is being run by a
normal user and is setuid root, with the "vi" line edit mode selected,
and the character set is "big5," an off-by-one errors occurs during
wildcard (glob) expansion.