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 * Sample BPF program to set send and receive buffers to 150KB, sndcwnd clamp
8*4882a593Smuzhiyun * to 100 packets and SYN and SYN_ACK RTOs to 10ms when both hosts are within
9*4882a593Smuzhiyun * the same datacenter. For his example, we assume they are within the same
10*4882a593Smuzhiyun * datacenter when the first 5.5 bytes of their IPv6 addresses are the same.
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_clamp(struct bpf_sock_ops * skops)26*4882a593Smuzhiyun int bpf_clamp(struct bpf_sock_ops *skops)
27*4882a593Smuzhiyun {
28*4882a593Smuzhiyun int bufsize = 150000;
29*4882a593Smuzhiyun int to_init = 10;
30*4882a593Smuzhiyun int clamp = 100;
31*4882a593Smuzhiyun int rv = 0;
32*4882a593Smuzhiyun int op;
33*4882a593Smuzhiyun
34*4882a593Smuzhiyun /* For testing purposes, only execute rest of BPF program
35*4882a593Smuzhiyun * if neither port numberis 55601
36*4882a593Smuzhiyun */
37*4882a593Smuzhiyun if (bpf_ntohl(skops->remote_port) != 55601 && skops->local_port != 55601) {
38*4882a593Smuzhiyun skops->reply = -1;
39*4882a593Smuzhiyun return 0;
40*4882a593Smuzhiyun }
41*4882a593Smuzhiyun
42*4882a593Smuzhiyun op = (int) skops->op;
43*4882a593Smuzhiyun
44*4882a593Smuzhiyun #ifdef DEBUG
45*4882a593Smuzhiyun bpf_printk("BPF command: %d\n", op);
46*4882a593Smuzhiyun #endif
47*4882a593Smuzhiyun
48*4882a593Smuzhiyun /* Check that both hosts are within same datacenter. For this example
49*4882a593Smuzhiyun * it is the case when the first 5.5 bytes of their IPv6 addresses are
50*4882a593Smuzhiyun * the same.
51*4882a593Smuzhiyun */
52*4882a593Smuzhiyun if (skops->family == AF_INET6 &&
53*4882a593Smuzhiyun skops->local_ip6[0] == skops->remote_ip6[0] &&
54*4882a593Smuzhiyun (bpf_ntohl(skops->local_ip6[1]) & 0xfff00000) ==
55*4882a593Smuzhiyun (bpf_ntohl(skops->remote_ip6[1]) & 0xfff00000)) {
56*4882a593Smuzhiyun switch (op) {
57*4882a593Smuzhiyun case BPF_SOCK_OPS_TIMEOUT_INIT:
58*4882a593Smuzhiyun rv = to_init;
59*4882a593Smuzhiyun break;
60*4882a593Smuzhiyun case BPF_SOCK_OPS_TCP_CONNECT_CB:
61*4882a593Smuzhiyun /* Set sndbuf and rcvbuf of active connections */
62*4882a593Smuzhiyun rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF,
63*4882a593Smuzhiyun &bufsize, sizeof(bufsize));
64*4882a593Smuzhiyun rv += bpf_setsockopt(skops, SOL_SOCKET,
65*4882a593Smuzhiyun SO_RCVBUF, &bufsize,
66*4882a593Smuzhiyun sizeof(bufsize));
67*4882a593Smuzhiyun break;
68*4882a593Smuzhiyun case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:
69*4882a593Smuzhiyun rv = bpf_setsockopt(skops, SOL_TCP,
70*4882a593Smuzhiyun TCP_BPF_SNDCWND_CLAMP,
71*4882a593Smuzhiyun &clamp, sizeof(clamp));
72*4882a593Smuzhiyun break;
73*4882a593Smuzhiyun case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
74*4882a593Smuzhiyun /* Set sndbuf and rcvbuf of passive connections */
75*4882a593Smuzhiyun rv = bpf_setsockopt(skops, SOL_TCP,
76*4882a593Smuzhiyun TCP_BPF_SNDCWND_CLAMP,
77*4882a593Smuzhiyun &clamp, sizeof(clamp));
78*4882a593Smuzhiyun rv += bpf_setsockopt(skops, SOL_SOCKET,
79*4882a593Smuzhiyun SO_SNDBUF, &bufsize,
80*4882a593Smuzhiyun sizeof(bufsize));
81*4882a593Smuzhiyun rv += bpf_setsockopt(skops, SOL_SOCKET,
82*4882a593Smuzhiyun SO_RCVBUF, &bufsize,
83*4882a593Smuzhiyun sizeof(bufsize));
84*4882a593Smuzhiyun break;
85*4882a593Smuzhiyun default:
86*4882a593Smuzhiyun rv = -1;
87*4882a593Smuzhiyun }
88*4882a593Smuzhiyun } else {
89*4882a593Smuzhiyun rv = -1;
90*4882a593Smuzhiyun }
91*4882a593Smuzhiyun #ifdef DEBUG
92*4882a593Smuzhiyun bpf_printk("Returning %d\n", rv);
93*4882a593Smuzhiyun #endif
94*4882a593Smuzhiyun skops->reply = rv;
95*4882a593Smuzhiyun return 1;
96*4882a593Smuzhiyun }
97*4882a593Smuzhiyun char _license[] SEC("license") = "GPL";
98