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/* Copyright (c) 2016 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.
*/
#define KBUILD_MODNAME "foo"
#include <linux/if_ether.h>
#include <linux/if_vlan.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/in.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <uapi/linux/bpf.h>
#include <net/ip.h>
#include <bpf/bpf_helpers.h>
#define DEFAULT_PKTGEN_UDP_PORT 9
#define DEBUG 0
static int tcp(void *data, uint64_t tp_off, void *data_end)
{
struct tcphdr *tcp = data + tp_off;
if (tcp + 1 > data_end)
return 0;
if (tcp->dest == htons(80) || tcp->source == htons(80))
return TC_ACT_SHOT;
return 0;
}
static int udp(void *data, uint64_t tp_off, void *data_end)
{
struct udphdr *udp = data + tp_off;
if (udp + 1 > data_end)
return 0;
if (udp->dest == htons(DEFAULT_PKTGEN_UDP_PORT) ||
udp->source == htons(DEFAULT_PKTGEN_UDP_PORT)) {
if (DEBUG) {
char fmt[] = "udp port 9 indeed\n";
bpf_trace_printk(fmt, sizeof(fmt));
}
return TC_ACT_SHOT;
}
return 0;
}
static int parse_ipv4(void *data, uint64_t nh_off, void *data_end)
{
struct iphdr *iph;
uint64_t ihl_len;
iph = data + nh_off;
if (iph + 1 > data_end)
return 0;
if (ip_is_fragment(iph))
return 0;
ihl_len = iph->ihl * 4;
if (iph->protocol == IPPROTO_IPIP) {
iph = data + nh_off + ihl_len;
if (iph + 1 > data_end)
return 0;
ihl_len += iph->ihl * 4;
}
if (iph->protocol == IPPROTO_TCP)
return tcp(data, nh_off + ihl_len, data_end);
else if (iph->protocol == IPPROTO_UDP)
return udp(data, nh_off + ihl_len, data_end);
return 0;
}
static int parse_ipv6(void *data, uint64_t nh_off, void *data_end)
{
struct ipv6hdr *ip6h;
struct iphdr *iph;
uint64_t ihl_len = sizeof(struct ipv6hdr);
uint64_t nexthdr;
ip6h = data + nh_off;
if (ip6h + 1 > data_end)
return 0;
nexthdr = ip6h->nexthdr;
if (nexthdr == IPPROTO_IPIP) {
iph = data + nh_off + ihl_len;
if (iph + 1 > data_end)
return 0;
ihl_len += iph->ihl * 4;
nexthdr = iph->protocol;
} else if (nexthdr == IPPROTO_IPV6) {
ip6h = data + nh_off + ihl_len;
if (ip6h + 1 > data_end)
return 0;
ihl_len += sizeof(struct ipv6hdr);
nexthdr = ip6h->nexthdr;
}
if (nexthdr == IPPROTO_TCP)
return tcp(data, nh_off + ihl_len, data_end);
else if (nexthdr == IPPROTO_UDP)
return udp(data, nh_off + ihl_len, data_end);
return 0;
}
SEC("varlen")
int handle_ingress(struct __sk_buff *skb)
{
void *data = (void *)(long)skb->data;
struct ethhdr *eth = data;
void *data_end = (void *)(long)skb->data_end;
uint64_t h_proto, nh_off;
nh_off = sizeof(*eth);
if (data + nh_off > data_end)
return 0;
h_proto = eth->h_proto;
if (h_proto == ETH_P_8021Q || h_proto == ETH_P_8021AD) {
struct vlan_hdr *vhdr;
vhdr = data + nh_off;
nh_off += sizeof(struct vlan_hdr);
if (data + nh_off > data_end)
return 0;
h_proto = vhdr->h_vlan_encapsulated_proto;
}
if (h_proto == ETH_P_8021Q || h_proto == ETH_P_8021AD) {
struct vlan_hdr *vhdr;
vhdr = data + nh_off;
nh_off += sizeof(struct vlan_hdr);
if (data + nh_off > data_end)
return 0;
h_proto = vhdr->h_vlan_encapsulated_proto;
}
if (h_proto == htons(ETH_P_IP))
return parse_ipv4(data, nh_off, data_end);
else if (h_proto == htons(ETH_P_IPV6))
return parse_ipv6(data, nh_off, data_end);
return 0;
}
char _license[] SEC("license") = "GPL";
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