On Tue, Oct 25, 2016 at 12:14:08PM +0200, Daniel Mack wrote: [...] > Dumping programs once they are installed is problematic because of > the internal optimizations done to the eBPF program during its > lifetime. Also, the references to maps etc. would need to be > restored during the dump. > > Just exposing whether or not a program is attached would be > trivial to do, however, most easily through another bpf(2) > command. That can be added later on though. I don't know if anyone told you, but during last netconf, this topic took a bit of time of discussion and it was controversial, I would say 1/3 of netdev hackers there showed their concerns, and that's something that should not be skipped IMO. While xdp is pushing bpf programs at the very early packet path, not interfering with the stack, before even entering the generic ingress path. But this is adding hooks to push bpf programs in the middle of our generic stack, this is way different domain. I would really like to explore way earlier filtering, by extending socket lookup facilities. So far the problem seems to be that we need to lookup for broadcast/multicast UDP sockets and those cannot be attach via the usual skb->sk. I think it would be possible to wrap around this socket code in functions so we can invoke it. I guess filtering of UDP and TCP should be good for you at this stage. This would require more work though, but this would come with no hooks in the stack and packets will not have to consume *lots of cycles* just to be dropped before entering the socket queue. How useful can be to drop lots of unwanted traffic at such a late stage? How would the performance numbers to drop packets would look like? Extremely bad, I predict. -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
