Re: Tempfile vulnerabilities

[vonbrand () SLEIPNIR VALPARAISO CL (Horst von Brand)]

Seth David Schoen <schoen () LOYALTY ORG> said:

[...]

> An intermediate possibility is to have multiple RNGs with multiple sources
> of entropy, or multiple RNGs with entropy divided among them somehow, or
> a single RNG which enforces a reasonable policy of some sort when multiple
> processes want to access it at once.

Linux has /dev/random (real random) and /dev/urandom (generated with help
of a RNG if not enough entropy in /dev/random). Just shut off people from
using /dev/random.

> Modern multiuser operating systems have solved all _kinds_ of problems around
> concurrency and dealing with contention over a shared resource.  There is
> no reason that they should not be able to do exactly the same thing for an
> entropy pool, if it becomes an issue.

The problem here is not a shared resource, it is a finite resource. And
solutions there (f.ex. disk space) are quotas or manual intervention. Sou
you'd have a /etc/random.quotas file saying which UID is allowed to use how
much entropy, and the kernel keeps track from there after being primed on
boot. Yuck.

--
Horst von Brand                             vonbrand () sleipnir valparaiso cl
Casilla 9G, Viña del Mar, Chile                               +56 32 672616