Messages in this thread | | | From | "Sean Hunter" <> | Date | Wed, 12 Jan 2000 15:59:41 +0000 | Subject | Re: RFC/PATCH: Random pid generation |
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On Wed, Jan 12, 2000 at 03:05:03PM +0100, Marcus Sundberg wrote: > "Sean Hunter" <sean@uncarved.co.uk> writes: > > > On Tue, Jan 11, 2000 at 08:20:54PM +0100, Marcus Sundberg wrote: > > > Stephen Frost <sfrost@ns.snowman.net> writes: > > > > > > > People use the PID to create temp files and whatnot, > > > > from what I've seen. > > > > > > And they do that in order to get a unique number, not a random number. > > > > This is also a really bad idea, because with easily guessable pids you > > are opening yourself to /tmp races. > > There can be only one process with a given pid at a time, so there can't > be anything I'd call a race.
You run your program, but I have created a simlink in /tmp with the same name (because the name is guessable). That is a race because it relies on contention between two processes (my "ln -s" and your broken program) over a shared resource (the easily-guessable name in the shared namespace of the filesystem). This is the definition of a race. You may not call it that, but everyone else would.
> Ofcourse there are security implications of handling files in /tmp, but > that is independent of how the filenames are generated and a completely > different story. A program that relies on non-guessable filenames in > /tmp to be secure is severly broken.
Agreed.
Sean
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