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

[Alexei Starovoitov]

On Thu, Dec 22, 2016 at 9:25 AM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
> On Thu, Dec 22, 2016 at 8:59 AM, Hannes Frederic Sowa
> <hannes@xxxxxxxxxxxxxxxxxxx> wrote:
>> 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.