1238104Sdes/* Copyright (c) 2017 Facebook 2238104Sdes * 3238104Sdes * This program is free software; you can redistribute it and/or 4238104Sdes * modify it under the terms of version 2 of the GNU General Public 5238104Sdes * License as published by the Free Software Foundation. 6238104Sdes * 7238104Sdes * BPF program to set congestion control to dctcp when both hosts are 8238104Sdes * in the same datacenter (as deteremined by IPv6 prefix). 9238104Sdes * 10238104Sdes * Use "bpftool cgroup attach $cg sock_ops $prog" to load this BPF program. 11238104Sdes */ 12238104Sdes 13238104Sdes#include <uapi/linux/bpf.h> 14238104Sdes#include <uapi/linux/tcp.h> 15238104Sdes#include <uapi/linux/if_ether.h> 16238104Sdes#include <uapi/linux/if_packet.h> 17238104Sdes#include <uapi/linux/ip.h> 18238104Sdes#include <linux/socket.h> 19238104Sdes#include <bpf/bpf_helpers.h> 20238104Sdes#include <bpf/bpf_endian.h> 21238104Sdes 22238104Sdes#define DEBUG 1 23238104Sdes 24238104SdesSEC("sockops") 25238104Sdesint bpf_cong(struct bpf_sock_ops *skops) 26238104Sdes{ 27238104Sdes char cong[] = "dctcp"; 28238104Sdes int rv = 0; 29238104Sdes int op; 30238104Sdes 31 /* For testing purposes, only execute rest of BPF program 32 * if neither port numberis 55601 33 */ 34 if (bpf_ntohl(skops->remote_port) != 55601 && 35 skops->local_port != 55601) { 36 skops->reply = -1; 37 return 1; 38 } 39 40 op = (int) skops->op; 41 42#ifdef DEBUG 43 bpf_printk("BPF command: %d\n", op); 44#endif 45 46 /* Check if both hosts are in the same datacenter. For this 47 * example they are if the 1st 5.5 bytes in the IPv6 address 48 * are the same. 49 */ 50 if (skops->family == AF_INET6 && 51 skops->local_ip6[0] == skops->remote_ip6[0] && 52 (bpf_ntohl(skops->local_ip6[1]) & 0xfff00000) == 53 (bpf_ntohl(skops->remote_ip6[1]) & 0xfff00000)) { 54 switch (op) { 55 case BPF_SOCK_OPS_NEEDS_ECN: 56 rv = 1; 57 break; 58 case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB: 59 rv = bpf_setsockopt(skops, SOL_TCP, TCP_CONGESTION, 60 cong, sizeof(cong)); 61 break; 62 case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: 63 rv = bpf_setsockopt(skops, SOL_TCP, TCP_CONGESTION, 64 cong, sizeof(cong)); 65 break; 66 default: 67 rv = -1; 68 } 69 } else { 70 rv = -1; 71 } 72#ifdef DEBUG 73 bpf_printk("Returning %d\n", rv); 74#endif 75 skops->reply = rv; 76 return 1; 77} 78char _license[] SEC("license") = "GPL"; 79