/* 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. * * Sample BPF program to set send and receive buffers to 150KB, sndcwnd clamp * to 100 packets and SYN and SYN_ACK RTOs to 10ms when both hosts are within * the same datacenter. For his example, we assume they are within the same * datacenter when the first 5.5 bytes of their IPv6 addresses are the same. * * 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/bpf_helpers.h> #include <bpf/bpf_endian.h> #define DEBUG 1 SEC("sockops") int bpf_clamp(struct bpf_sock_ops *skops) { int bufsize = 150000; int to_init = 10; int clamp = 100; 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 0; } op = (int) skops->op; #ifdef DEBUG bpf_printk("BPF command: %d\n", op); #endif /* Check that both hosts are within same datacenter. For this example * it is the case when the first 5.5 bytes of their IPv6 addresses are * the same. */ if (skops->family == AF_INET6 && skops->local_ip6[0] == skops->remote_ip6[0] && (bpf_ntohl(skops->local_ip6[1]) & 0xfff00000) == (bpf_ntohl(skops->remote_ip6[1]) & 0xfff00000)) { switch (op) { case BPF_SOCK_OPS_TIMEOUT_INIT: rv = to_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_SNDCWND_CLAMP, &clamp, sizeof(clamp)); break; case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: /* Set sndbuf and rcvbuf of passive connections */ rv = bpf_setsockopt(skops, SOL_TCP, TCP_BPF_SNDCWND_CLAMP, &clamp, sizeof(clamp)); 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; } } else { rv = -1; } #ifdef DEBUG bpf_printk("Returning %d\n", rv); #endif skops->reply = rv; return 1; } char _license[] SEC("license") = "GPL";