LXR linux/samples/bpf/tcp_bufs

   1/* Copyright (c) 2017 Facebook
   2 *
   3 * This program is free software; you can redistribute it and/or
   4 * modify it under the terms of version 2 of the GNU General Public
   5 * License as published by the Free Software Foundation.
   6 *
   7 * BPF program to set initial receive window to 40 packets and send
   8 * and receive buffers to 1.5MB. This would usually be done after
   9 * doing appropriate checks that indicate the hosts are far enough
  10 * away (i.e. large RTT).
  11 *
  12 * Use "bpftool cgroup attach $cg sock_ops $prog" to load this BPF program.
  13 */
  14
  15#include <uapi/linux/bpf.h>
  16#include <uapi/linux/if_ether.h>
  17#include <uapi/linux/if_packet.h>
  18#include <uapi/linux/ip.h>
  19#include <linux/socket.h>
  20#include <bpf/bpf_helpers.h>
  21#include <bpf/bpf_endian.h>
  22
  23#define DEBUG 1
  24
  25SEC("sockops")
  26int bpf_bufs(struct bpf_sock_ops *skops)
  27{
  28        int bufsize = 1500000;
  29        int rwnd_init = 40;
  30        int rv = 0;
  31        int op;
  32
  33        /* For testing purposes, only execute rest of BPF program
  34         * if neither port numberis 55601
  35         */
  36        if (bpf_ntohl(skops->remote_port) != 55601 &&
  37            skops->local_port != 55601) {
  38                skops->reply = -1;
  39                return 1;
  40        }
  41
  42        op = (int) skops->op;
  43
  44#ifdef DEBUG
  45        bpf_printk("Returning %d\n", rv);
  46#endif
  47
  48        /* Usually there would be a check to insure the hosts are far
  49         * from each other so it makes sense to increase buffer sizes
  50         */
  51        switch (op) {
  52        case BPF_SOCK_OPS_RWND_INIT:
  53                rv = rwnd_init;
  54                break;
  55        case BPF_SOCK_OPS_TCP_CONNECT_CB:
  56                /* Set sndbuf and rcvbuf of active connections */
  57                rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize,
  58                                    sizeof(bufsize));
  59                rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF,
  60                                     &bufsize, sizeof(bufsize));
  61                break;
  62        case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:
  63                /* Nothing to do */
  64                break;
  65        case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
  66                /* Set sndbuf and rcvbuf of passive connections */
  67                rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize,
  68                                    sizeof(bufsize));
  69                rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF,
  70                                     &bufsize, sizeof(bufsize));
  71                break;
  72        default:
  73                rv = -1;
  74        }
  75#ifdef DEBUG
  76        bpf_printk("Returning %d\n", rv);
  77#endif
  78        skops->reply = rv;
  79        return 1;
  80}
  81char _license[] SEC("license") = "GPL";
  82