| /* Copyright (c) 2017 Facebook |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of version 2 of the GNU General Public |
| * License as published by the Free Software Foundation. |
| * |
| * BPF program to set initial congestion window and initial receive |
| * window to 40 packets and send and receive buffers to 1.5MB. This |
| * would usually be done after doing appropriate checks that indicate |
| * the hosts are far enough away (i.e. large RTT). |
| * |
| * Use "bpftool cgroup attach $cg sock_ops $prog" to load this BPF program. |
| */ |
| |
| #include <uapi/linux/bpf.h> |
| #include <uapi/linux/if_ether.h> |
| #include <uapi/linux/if_packet.h> |
| #include <uapi/linux/ip.h> |
| #include <linux/socket.h> |
| #include "bpf_helpers.h" |
| #include "bpf_endian.h" |
| |
| #define DEBUG 1 |
| |
| #define bpf_printk(fmt, ...) \ |
| ({ \ |
| char ____fmt[] = fmt; \ |
| bpf_trace_printk(____fmt, sizeof(____fmt), \ |
| ##__VA_ARGS__); \ |
| }) |
| |
| SEC("sockops") |
| int bpf_iw(struct bpf_sock_ops *skops) |
| { |
| int bufsize = 1500000; |
| int rwnd_init = 40; |
| int iw = 40; |
| int rv = 0; |
| int op; |
| |
| /* For testing purposes, only execute rest of BPF program |
| * if neither port numberis 55601 |
| */ |
| if (bpf_ntohl(skops->remote_port) != 55601 && |
| skops->local_port != 55601) { |
| skops->reply = -1; |
| return 1; |
| } |
| |
| op = (int) skops->op; |
| |
| #ifdef DEBUG |
| bpf_printk("BPF command: %d\n", op); |
| #endif |
| |
| /* Usually there would be a check to insure the hosts are far |
| * from each other so it makes sense to increase buffer sizes |
| */ |
| switch (op) { |
| case BPF_SOCK_OPS_RWND_INIT: |
| rv = rwnd_init; |
| break; |
| case BPF_SOCK_OPS_TCP_CONNECT_CB: |
| /* Set sndbuf and rcvbuf of active connections */ |
| rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize, |
| sizeof(bufsize)); |
| rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF, |
| &bufsize, sizeof(bufsize)); |
| break; |
| case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB: |
| rv = bpf_setsockopt(skops, SOL_TCP, TCP_BPF_IW, &iw, |
| sizeof(iw)); |
| break; |
| case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: |
| /* Set sndbuf and rcvbuf of passive connections */ |
| rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize, |
| sizeof(bufsize)); |
| rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF, |
| &bufsize, sizeof(bufsize)); |
| break; |
| default: |
| rv = -1; |
| } |
| #ifdef DEBUG |
| bpf_printk("Returning %d\n", rv); |
| #endif |
| skops->reply = rv; |
| return 1; |
| } |
| char _license[] SEC("license") = "GPL"; |