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 load_sock_ops 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_bufs(struct bpf_sock_ops *skops) 34 { 35 int bufsize = 1500000; 36 int rwnd_init = 40; 37 int rv = 0; 38 int op; 39 40 /* For testing purposes, only execute rest of BPF program 41 * if neither port numberis 55601 42 */ 43 if (bpf_ntohl(skops->remote_port) != 55601 && 44 skops->local_port != 55601) { 45 skops->reply = -1; 46 return 1; 47 } 48 49 op = (int) skops->op; 50 51 #ifdef DEBUG 52 bpf_printk("Returning %d\n", rv); 53 #endif 54 55 /* Usually there would be a check to insure the hosts are far 56 * from each other so it makes sense to increase buffer sizes 57 */ 58 switch (op) { 59 case BPF_SOCK_OPS_RWND_INIT: 60 rv = rwnd_init; 61 break; 62 case BPF_SOCK_OPS_TCP_CONNECT_CB: 63 /* Set sndbuf and rcvbuf of active connections */ 64 rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize, 65 sizeof(bufsize)); 66 rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF, 67 &bufsize, sizeof(bufsize)); 68 break; 69 case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB: 70 /* Nothing to do */ 71 break; 72 case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: 73 /* Set sndbuf and rcvbuf of passive connections */ 74 rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize, 75 sizeof(bufsize)); 76 rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF, 77 &bufsize, sizeof(bufsize)); 78 break; 79 default: 80 rv = -1; 81 } 82 #ifdef DEBUG 83 bpf_printk("Returning %d\n", rv); 84 #endif 85 skops->reply = rv; 86 return 1; 87 } 88 char _license[] SEC("license") = "GPL"; 89