1c400296bSLawrence Brakmo /* Copyright (c) 2017 Facebook 2c400296bSLawrence Brakmo * 3c400296bSLawrence Brakmo * This program is free software; you can redistribute it and/or 4c400296bSLawrence Brakmo * modify it under the terms of version 2 of the GNU General Public 5c400296bSLawrence Brakmo * License as published by the Free Software Foundation. 6c400296bSLawrence Brakmo * 7c400296bSLawrence Brakmo * BPF program to set initial receive window to 40 packets when using IPv6 8c400296bSLawrence Brakmo * and the first 5.5 bytes of the IPv6 addresses are not the same (in this 9c400296bSLawrence Brakmo * example that means both hosts are not the same datacenter). 10c400296bSLawrence Brakmo * 11ea9b6362SJakub Kicinski * Use "bpftool cgroup attach $cg sock_ops $prog" to load this BPF program. 12c400296bSLawrence Brakmo */ 13c400296bSLawrence Brakmo 14c400296bSLawrence Brakmo #include <uapi/linux/bpf.h> 15c400296bSLawrence Brakmo #include <uapi/linux/if_ether.h> 16c400296bSLawrence Brakmo #include <uapi/linux/if_packet.h> 17c400296bSLawrence Brakmo #include <uapi/linux/ip.h> 18c400296bSLawrence Brakmo #include <linux/socket.h> 19*7cf245a3SToke Høiland-Jørgensen #include <bpf/bpf_helpers.h> 20*7cf245a3SToke Høiland-Jørgensen #include <bpf/bpf_endian.h> 21c400296bSLawrence Brakmo 22c400296bSLawrence Brakmo #define DEBUG 1 23c400296bSLawrence Brakmo 24c400296bSLawrence Brakmo SEC("sockops") bpf_rwnd(struct bpf_sock_ops * skops)25c400296bSLawrence Brakmoint bpf_rwnd(struct bpf_sock_ops *skops) 26c400296bSLawrence Brakmo { 27c400296bSLawrence Brakmo int rv = -1; 28c400296bSLawrence Brakmo int op; 29c400296bSLawrence Brakmo 30c400296bSLawrence Brakmo /* For testing purposes, only execute rest of BPF program 31c400296bSLawrence Brakmo * if neither port numberis 55601 32c400296bSLawrence Brakmo */ 33c400296bSLawrence Brakmo if (bpf_ntohl(skops->remote_port) != 34016e661bSLawrence Brakmo 55601 && skops->local_port != 55601) { 35016e661bSLawrence Brakmo skops->reply = -1; 36016e661bSLawrence Brakmo return 1; 37016e661bSLawrence Brakmo } 38c400296bSLawrence Brakmo 39c400296bSLawrence Brakmo op = (int) skops->op; 40c400296bSLawrence Brakmo 41c400296bSLawrence Brakmo #ifdef DEBUG 42c400296bSLawrence Brakmo bpf_printk("BPF command: %d\n", op); 43c400296bSLawrence Brakmo #endif 44c400296bSLawrence Brakmo 45c400296bSLawrence Brakmo /* Check for RWND_INIT operation and IPv6 addresses */ 46c400296bSLawrence Brakmo if (op == BPF_SOCK_OPS_RWND_INIT && 47c400296bSLawrence Brakmo skops->family == AF_INET6) { 48c400296bSLawrence Brakmo 49c400296bSLawrence Brakmo /* If the first 5.5 bytes of the IPv6 address are not the same 50c400296bSLawrence Brakmo * then both hosts are not in the same datacenter 51c400296bSLawrence Brakmo * so use a larger initial advertized window (40 packets) 52c400296bSLawrence Brakmo */ 53c400296bSLawrence Brakmo if (skops->local_ip6[0] != skops->remote_ip6[0] || 54c400296bSLawrence Brakmo (bpf_ntohl(skops->local_ip6[1]) & 0xfffff000) != 55c400296bSLawrence Brakmo (bpf_ntohl(skops->remote_ip6[1]) & 0xfffff000)) 56c400296bSLawrence Brakmo rv = 40; 57c400296bSLawrence Brakmo } 58c400296bSLawrence Brakmo #ifdef DEBUG 59c400296bSLawrence Brakmo bpf_printk("Returning %d\n", rv); 60c400296bSLawrence Brakmo #endif 61c400296bSLawrence Brakmo skops->reply = rv; 62c400296bSLawrence Brakmo return 1; 63c400296bSLawrence Brakmo } 64c400296bSLawrence Brakmo char _license[] SEC("license") = "GPL"; 65