cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

tcp_cong_kern.c (1962B)

      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 congestion control to dctcp when both hosts are
      8 * in the same datacenter (as deteremined by IPv6 prefix).
      9 *
     10 * Use "bpftool cgroup attach $cg sock_ops $prog" to load this BPF program.
     11 */
     12
     13#include <uapi/linux/bpf.h>
     14#include <uapi/linux/tcp.h>
     15#include <uapi/linux/if_ether.h>
     16#include <uapi/linux/if_packet.h>
     17#include <uapi/linux/ip.h>
     18#include <linux/socket.h>
     19#include <bpf/bpf_helpers.h>
     20#include <bpf/bpf_endian.h>
     21
     22#define DEBUG 1
     23
     24SEC("sockops")
     25int bpf_cong(struct bpf_sock_ops *skops)
     26{
     27	char cong[] = "dctcp";
     28	int rv = 0;
     29	int op;
     30
     31	/* For testing purposes, only execute rest of BPF program
     32	 * if neither port numberis 55601
     33	 */
     34	if (bpf_ntohl(skops->remote_port) != 55601 &&
     35	    skops->local_port != 55601) {
     36		skops->reply = -1;
     37		return 1;
     38	}
     39
     40	op = (int) skops->op;
     41
     42#ifdef DEBUG
     43	bpf_printk("BPF command: %d\n", op);
     44#endif
     45
     46	/* Check if both hosts are in the same datacenter. For this
     47	 * example they are if the 1st 5.5 bytes in the IPv6 address
     48	 * are the same.
     49	 */
     50	if (skops->family == AF_INET6 &&
     51	    skops->local_ip6[0] == skops->remote_ip6[0] &&
     52	    (bpf_ntohl(skops->local_ip6[1]) & 0xfff00000) ==
     53	    (bpf_ntohl(skops->remote_ip6[1]) & 0xfff00000)) {
     54		switch (op) {
     55		case BPF_SOCK_OPS_NEEDS_ECN:
     56			rv = 1;
     57			break;
     58		case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:
     59			rv = bpf_setsockopt(skops, SOL_TCP, TCP_CONGESTION,
     60					    cong, sizeof(cong));
     61			break;
     62		case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
     63			rv = bpf_setsockopt(skops, SOL_TCP, TCP_CONGESTION,
     64					    cong, sizeof(cong));
     65			break;
     66		default:
     67			rv = -1;
     68		}
     69	} else {
     70		rv = -1;
     71	}
     72#ifdef DEBUG
     73	bpf_printk("Returning %d\n", rv);
     74#endif
     75	skops->reply = rv;
     76	return 1;
     77}
     78char _license[] SEC("license") = "GPL";