Re: world readable temp files and bash? set -C, noclobber (gnustandards suggestion and/or question)

[Ralf Wildenhues]

Hi Karl, Michael,

* Karl Berry wrote on Thu, Jan 27, 2011 at 02:42:32AM CET:
>     Is the problem mentioned in the standards the same with the one described 
> here?
>     http://www.linuxsecurity.com/content/view/115462/151/
> 
> Yes.
> 
>     If yes, then, maybe, advice to use mktemp would be more appropriate?
> 
> Mentioning mktemp is a good idea.  But doesn't noclobber also avoid the
> security problem (though in an inferior way), because either your
> program or the attacker's will fail to create the file, with noclobber
> set.

Right.

> Here's my attempt at a new paragraph:
> 
>   In bash, use @code{set -C} (long name @code{noclobber}) to avoid this
>   problem; the @code{mktemp} utility is a more general solution for
>   creating temporary files from shell scripts (@pxref{mktemp
>   invocation,,, coreutils, GNU Coreutils}).

Sounds better.  You could mention that mktemp is available everywhere.
'info Autoconf --index mktemp' also has a recommendation for a portable
alternative.  And for the $RANDOM alternative mentioned there, noclobber
would be a nice additional measure.

Cheers,
Ralf