1bb56d444SLawrence Brakmo /* Copyright (c) 2017 Facebook 2bb56d444SLawrence Brakmo * 3bb56d444SLawrence Brakmo * This program is free software; you can redistribute it and/or 4bb56d444SLawrence Brakmo * modify it under the terms of version 2 of the GNU General Public 5bb56d444SLawrence Brakmo * License as published by the Free Software Foundation. 6bb56d444SLawrence Brakmo * 7bb56d444SLawrence Brakmo * BPF program to set congestion control to dctcp when both hosts are 8bb56d444SLawrence Brakmo * in the same datacenter (as deteremined by IPv6 prefix). 9bb56d444SLawrence Brakmo * 10ea9b6362SJakub Kicinski * Use "bpftool cgroup attach $cg sock_ops $prog" to load this BPF program. 11bb56d444SLawrence Brakmo */ 12bb56d444SLawrence Brakmo 13bb56d444SLawrence Brakmo #include <uapi/linux/bpf.h> 14bb56d444SLawrence Brakmo #include <uapi/linux/tcp.h> 15bb56d444SLawrence Brakmo #include <uapi/linux/if_ether.h> 16bb56d444SLawrence Brakmo #include <uapi/linux/if_packet.h> 17bb56d444SLawrence Brakmo #include <uapi/linux/ip.h> 18bb56d444SLawrence Brakmo #include <linux/socket.h> 19*7cf245a3SToke Høiland-Jørgensen #include <bpf/bpf_helpers.h> 20*7cf245a3SToke Høiland-Jørgensen #include <bpf/bpf_endian.h> 21bb56d444SLawrence Brakmo 22bb56d444SLawrence Brakmo #define DEBUG 1 23bb56d444SLawrence Brakmo 24bb56d444SLawrence Brakmo SEC("sockops") 25bb56d444SLawrence Brakmo int bpf_cong(struct bpf_sock_ops *skops) 26bb56d444SLawrence Brakmo { 27bb56d444SLawrence Brakmo char cong[] = "dctcp"; 28bb56d444SLawrence Brakmo int rv = 0; 29bb56d444SLawrence Brakmo int op; 30bb56d444SLawrence Brakmo 31bb56d444SLawrence Brakmo /* For testing purposes, only execute rest of BPF program 32bb56d444SLawrence Brakmo * if neither port numberis 55601 33bb56d444SLawrence Brakmo */ 34bb56d444SLawrence Brakmo if (bpf_ntohl(skops->remote_port) != 55601 && 352ff969fbSLawrence Brakmo skops->local_port != 55601) { 362ff969fbSLawrence Brakmo skops->reply = -1; 372ff969fbSLawrence Brakmo return 1; 382ff969fbSLawrence Brakmo } 39bb56d444SLawrence Brakmo 40bb56d444SLawrence Brakmo op = (int) skops->op; 41bb56d444SLawrence Brakmo 42bb56d444SLawrence Brakmo #ifdef DEBUG 43bb56d444SLawrence Brakmo bpf_printk("BPF command: %d\n", op); 44bb56d444SLawrence Brakmo #endif 45bb56d444SLawrence Brakmo 46bb56d444SLawrence Brakmo /* Check if both hosts are in the same datacenter. For this 47bb56d444SLawrence Brakmo * example they are if the 1st 5.5 bytes in the IPv6 address 48bb56d444SLawrence Brakmo * are the same. 49bb56d444SLawrence Brakmo */ 50bb56d444SLawrence Brakmo if (skops->family == AF_INET6 && 51bb56d444SLawrence Brakmo skops->local_ip6[0] == skops->remote_ip6[0] && 52bb56d444SLawrence Brakmo (bpf_ntohl(skops->local_ip6[1]) & 0xfff00000) == 53bb56d444SLawrence Brakmo (bpf_ntohl(skops->remote_ip6[1]) & 0xfff00000)) { 54bb56d444SLawrence Brakmo switch (op) { 55bb56d444SLawrence Brakmo case BPF_SOCK_OPS_NEEDS_ECN: 56bb56d444SLawrence Brakmo rv = 1; 57bb56d444SLawrence Brakmo break; 58bb56d444SLawrence Brakmo case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB: 59bb56d444SLawrence Brakmo rv = bpf_setsockopt(skops, SOL_TCP, TCP_CONGESTION, 60bb56d444SLawrence Brakmo cong, sizeof(cong)); 61bb56d444SLawrence Brakmo break; 62bb56d444SLawrence Brakmo case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: 63bb56d444SLawrence Brakmo rv = bpf_setsockopt(skops, SOL_TCP, TCP_CONGESTION, 64bb56d444SLawrence Brakmo cong, sizeof(cong)); 65bb56d444SLawrence Brakmo break; 66bb56d444SLawrence Brakmo default: 67bb56d444SLawrence Brakmo rv = -1; 68bb56d444SLawrence Brakmo } 69bb56d444SLawrence Brakmo } else { 70bb56d444SLawrence Brakmo rv = -1; 71bb56d444SLawrence Brakmo } 72bb56d444SLawrence Brakmo #ifdef DEBUG 73bb56d444SLawrence Brakmo bpf_printk("Returning %d\n", rv); 74bb56d444SLawrence Brakmo #endif 75bb56d444SLawrence Brakmo skops->reply = rv; 76bb56d444SLawrence Brakmo return 1; 77bb56d444SLawrence Brakmo } 78bb56d444SLawrence Brakmo char _license[] SEC("license") = "GPL"; 79