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 SEC("sockops") 26 int bpf_iw(struct bpf_sock_ops *skops) 27 { 28 int bufsize = 1500000; 29 int rwnd_init = 40; 30 int iw = 40; 31 int rv = 0; 32 int op; 33 34 /* For testing purposes, only execute rest of BPF program 35 * if neither port numberis 55601 36 */ 37 if (bpf_ntohl(skops->remote_port) != 55601 && 38 skops->local_port != 55601) { 39 skops->reply = -1; 40 return 1; 41 } 42 43 op = (int) skops->op; 44 45 #ifdef DEBUG 46 bpf_printk("BPF command: %d\n", op); 47 #endif 48 49 /* Usually there would be a check to insure the hosts are far 50 * from each other so it makes sense to increase buffer sizes 51 */ 52 switch (op) { 53 case BPF_SOCK_OPS_RWND_INIT: 54 rv = rwnd_init; 55 break; 56 case BPF_SOCK_OPS_TCP_CONNECT_CB: 57 /* Set sndbuf and rcvbuf of active connections */ 58 rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize, 59 sizeof(bufsize)); 60 rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF, 61 &bufsize, sizeof(bufsize)); 62 break; 63 case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB: 64 rv = bpf_setsockopt(skops, SOL_TCP, TCP_BPF_IW, &iw, 65 sizeof(iw)); 66 break; 67 case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: 68 /* Set sndbuf and rcvbuf of passive connections */ 69 rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize, 70 sizeof(bufsize)); 71 rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF, 72 &bufsize, sizeof(bufsize)); 73 break; 74 default: 75 rv = -1; 76 } 77 #ifdef DEBUG 78 bpf_printk("Returning %d\n", rv); 79 #endif 80 skops->reply = rv; 81 return 1; 82 } 83 char _license[] SEC("license") = "GPL"; 84