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 return -1; 46 47 op = (int) skops->op; 48 49 #ifdef DEBUG 50 bpf_printk("Returning %d\n", rv); 51 #endif 52 53 /* Usually there would be a check to insure the hosts are far 54 * from each other so it makes sense to increase buffer sizes 55 */ 56 switch (op) { 57 case BPF_SOCK_OPS_RWND_INIT: 58 rv = rwnd_init; 59 break; 60 case BPF_SOCK_OPS_TCP_CONNECT_CB: 61 /* Set sndbuf and rcvbuf of active connections */ 62 rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize, 63 sizeof(bufsize)); 64 rv = rv*100 + bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF, 65 &bufsize, sizeof(bufsize)); 66 break; 67 case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB: 68 /* Nothing to do */ 69 break; 70 case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: 71 /* Set sndbuf and rcvbuf of passive connections */ 72 rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize, 73 sizeof(bufsize)); 74 rv = rv*100 + bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF, 75 &bufsize, sizeof(bufsize)); 76 break; 77 default: 78 rv = -1; 79 } 80 #ifdef DEBUG 81 bpf_printk("Returning %d\n", rv); 82 #endif 83 skops->reply = rv; 84 return 1; 85 } 86 char _license[] SEC("license") = "GPL"; 87