1*4882a593Smuzhiyun /* Copyright (c) 2017 Facebook
2*4882a593Smuzhiyun *
3*4882a593Smuzhiyun * This program is free software; you can redistribute it and/or
4*4882a593Smuzhiyun * modify it under the terms of version 2 of the GNU General Public
5*4882a593Smuzhiyun * License as published by the Free Software Foundation.
6*4882a593Smuzhiyun *
7*4882a593Smuzhiyun * BPF program to set initial receive window to 40 packets and send
8*4882a593Smuzhiyun * and receive buffers to 1.5MB. This would usually be done after
9*4882a593Smuzhiyun * doing appropriate checks that indicate the hosts are far enough
10*4882a593Smuzhiyun * away (i.e. large RTT).
11*4882a593Smuzhiyun *
12*4882a593Smuzhiyun * Use "bpftool cgroup attach $cg sock_ops $prog" to load this BPF program.
13*4882a593Smuzhiyun */
14*4882a593Smuzhiyun
15*4882a593Smuzhiyun #include <uapi/linux/bpf.h>
16*4882a593Smuzhiyun #include <uapi/linux/if_ether.h>
17*4882a593Smuzhiyun #include <uapi/linux/if_packet.h>
18*4882a593Smuzhiyun #include <uapi/linux/ip.h>
19*4882a593Smuzhiyun #include <linux/socket.h>
20*4882a593Smuzhiyun #include <bpf/bpf_helpers.h>
21*4882a593Smuzhiyun #include <bpf/bpf_endian.h>
22*4882a593Smuzhiyun
23*4882a593Smuzhiyun #define DEBUG 1
24*4882a593Smuzhiyun
25*4882a593Smuzhiyun SEC("sockops")
bpf_bufs(struct bpf_sock_ops * skops)26*4882a593Smuzhiyun int bpf_bufs(struct bpf_sock_ops *skops)
27*4882a593Smuzhiyun {
28*4882a593Smuzhiyun int bufsize = 1500000;
29*4882a593Smuzhiyun int rwnd_init = 40;
30*4882a593Smuzhiyun int rv = 0;
31*4882a593Smuzhiyun int op;
32*4882a593Smuzhiyun
33*4882a593Smuzhiyun /* For testing purposes, only execute rest of BPF program
34*4882a593Smuzhiyun * if neither port numberis 55601
35*4882a593Smuzhiyun */
36*4882a593Smuzhiyun if (bpf_ntohl(skops->remote_port) != 55601 &&
37*4882a593Smuzhiyun skops->local_port != 55601) {
38*4882a593Smuzhiyun skops->reply = -1;
39*4882a593Smuzhiyun return 1;
40*4882a593Smuzhiyun }
41*4882a593Smuzhiyun
42*4882a593Smuzhiyun op = (int) skops->op;
43*4882a593Smuzhiyun
44*4882a593Smuzhiyun #ifdef DEBUG
45*4882a593Smuzhiyun bpf_printk("Returning %d\n", rv);
46*4882a593Smuzhiyun #endif
47*4882a593Smuzhiyun
48*4882a593Smuzhiyun /* Usually there would be a check to insure the hosts are far
49*4882a593Smuzhiyun * from each other so it makes sense to increase buffer sizes
50*4882a593Smuzhiyun */
51*4882a593Smuzhiyun switch (op) {
52*4882a593Smuzhiyun case BPF_SOCK_OPS_RWND_INIT:
53*4882a593Smuzhiyun rv = rwnd_init;
54*4882a593Smuzhiyun break;
55*4882a593Smuzhiyun case BPF_SOCK_OPS_TCP_CONNECT_CB:
56*4882a593Smuzhiyun /* Set sndbuf and rcvbuf of active connections */
57*4882a593Smuzhiyun rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize,
58*4882a593Smuzhiyun sizeof(bufsize));
59*4882a593Smuzhiyun rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF,
60*4882a593Smuzhiyun &bufsize, sizeof(bufsize));
61*4882a593Smuzhiyun break;
62*4882a593Smuzhiyun case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:
63*4882a593Smuzhiyun /* Nothing to do */
64*4882a593Smuzhiyun break;
65*4882a593Smuzhiyun case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
66*4882a593Smuzhiyun /* Set sndbuf and rcvbuf of passive connections */
67*4882a593Smuzhiyun rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize,
68*4882a593Smuzhiyun sizeof(bufsize));
69*4882a593Smuzhiyun rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF,
70*4882a593Smuzhiyun &bufsize, sizeof(bufsize));
71*4882a593Smuzhiyun break;
72*4882a593Smuzhiyun default:
73*4882a593Smuzhiyun rv = -1;
74*4882a593Smuzhiyun }
75*4882a593Smuzhiyun #ifdef DEBUG
76*4882a593Smuzhiyun bpf_printk("Returning %d\n", rv);
77*4882a593Smuzhiyun #endif
78*4882a593Smuzhiyun skops->reply = rv;
79*4882a593Smuzhiyun return 1;
80*4882a593Smuzhiyun }
81*4882a593Smuzhiyun char _license[] SEC("license") = "GPL";
82