Re: BPF hash algo (Re: [kernel-hardening] Re: [PATCH v7 3/6] random: use SipHash in place of MD5)

On Thu, Dec 22, 2016 at 9:25 AM, Andy Lutomirski [off-list ref] wrote:

On Thu, Dec 22, 2016 at 8:59 AM, Hannes Frederic Sowa
[off-list ref] wrote:

quoted

On Thu, 2016-12-22 at 08:07 -0800, Andy Lutomirski wrote:

We don't prevent ebpf programs being loaded based on the digest but
just to uniquely identify loaded programs from user space and match up
with their source.

The commit log talks about using the hash to see if the program has
already been compiled and JITted.  If that's done, then a collision
will directly cause the kernel to malfunction.

Andy, please read the code.
we could have used jhash there just as well.
Collisions are fine.