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 congestion window and initial receive 8 * window to 40 packets and send and receive buffers to 1.5MB. This 9 * would usually be done after doing appropriate checks that indicate 10 * the hosts are far enough 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_helpers.h" 21 #include "bpf_endian.h" 22 23 #define DEBUG 1 24 25 #define bpf_printk(fmt, ...) \ 26 ({ \ 27 char ____fmt[] = fmt; \ 28 bpf_trace_printk(____fmt, sizeof(____fmt), \ 29 ##__VA_ARGS__); \ 30 }) 31 32 SEC("sockops") 33 int bpf_iw(struct bpf_sock_ops *skops) 34 { 35 int bufsize = 1500000; 36 int rwnd_init = 40; 37 int iw = 40; 38 int rv = 0; 39 int op; 40 41 /* For testing purposes, only execute rest of BPF program 42 * if neither port numberis 55601 43 */ 44 if (bpf_ntohl(skops->remote_port) != 55601 && 45 skops->local_port != 55601) { 46 skops->reply = -1; 47 return 1; 48 } 49 50 op = (int) skops->op; 51 52 #ifdef DEBUG 53 bpf_printk("BPF command: %d\n", op); 54 #endif 55 56 /* Usually there would be a check to insure the hosts are far 57 * from each other so it makes sense to increase buffer sizes 58 */ 59 switch (op) { 60 case BPF_SOCK_OPS_RWND_INIT: 61 rv = rwnd_init; 62 break; 63 case BPF_SOCK_OPS_TCP_CONNECT_CB: 64 /* Set sndbuf and rcvbuf of active connections */ 65 rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize, 66 sizeof(bufsize)); 67 rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF, 68 &bufsize, sizeof(bufsize)); 69 break; 70 case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB: 71 rv = bpf_setsockopt(skops, SOL_TCP, TCP_BPF_IW, &iw, 72 sizeof(iw)); 73 break; 74 case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: 75 /* Set sndbuf and rcvbuf of passive connections */ 76 rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize, 77 sizeof(bufsize)); 78 rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF, 79 &bufsize, sizeof(bufsize)); 80 break; 81 default: 82 rv = -1; 83 } 84 #ifdef DEBUG 85 bpf_printk("Returning %d\n", rv); 86 #endif 87 skops->reply = rv; 88 return 1; 89 } 90 char _license[] SEC("license") = "GPL"; 91