155 lines
3.5 KiB
C
155 lines
3.5 KiB
C
/* Copyright (c) 2016 Facebook
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#define KBUILD_MODNAME "foo"
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#include <linux/if_ether.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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#include <linux/in.h>
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#include <linux/tcp.h>
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#include <linux/udp.h>
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#include <uapi/linux/bpf.h>
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#include <net/ip.h>
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#include "bpf_helpers.h"
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#define DEFAULT_PKTGEN_UDP_PORT 9
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#define DEBUG 0
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static int tcp(void *data, uint64_t tp_off, void *data_end)
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{
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struct tcphdr *tcp = data + tp_off;
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if (tcp + 1 > data_end)
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return 0;
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if (tcp->dest == htons(80) || tcp->source == htons(80))
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return TC_ACT_SHOT;
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return 0;
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}
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static int udp(void *data, uint64_t tp_off, void *data_end)
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{
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struct udphdr *udp = data + tp_off;
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if (udp + 1 > data_end)
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return 0;
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if (udp->dest == htons(DEFAULT_PKTGEN_UDP_PORT) ||
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udp->source == htons(DEFAULT_PKTGEN_UDP_PORT)) {
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if (DEBUG) {
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char fmt[] = "udp port 9 indeed\n";
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bpf_trace_printk(fmt, sizeof(fmt));
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}
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return TC_ACT_SHOT;
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}
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return 0;
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}
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static int parse_ipv4(void *data, uint64_t nh_off, void *data_end)
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{
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struct iphdr *iph;
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uint64_t ihl_len;
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iph = data + nh_off;
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if (iph + 1 > data_end)
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return 0;
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if (ip_is_fragment(iph))
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return 0;
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ihl_len = iph->ihl * 4;
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if (iph->protocol == IPPROTO_IPIP) {
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iph = data + nh_off + ihl_len;
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if (iph + 1 > data_end)
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return 0;
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ihl_len += iph->ihl * 4;
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}
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if (iph->protocol == IPPROTO_TCP)
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return tcp(data, nh_off + ihl_len, data_end);
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else if (iph->protocol == IPPROTO_UDP)
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return udp(data, nh_off + ihl_len, data_end);
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return 0;
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}
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static int parse_ipv6(void *data, uint64_t nh_off, void *data_end)
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{
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struct ipv6hdr *ip6h;
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struct iphdr *iph;
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uint64_t ihl_len = sizeof(struct ipv6hdr);
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uint64_t nexthdr;
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ip6h = data + nh_off;
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if (ip6h + 1 > data_end)
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return 0;
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nexthdr = ip6h->nexthdr;
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if (nexthdr == IPPROTO_IPIP) {
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iph = data + nh_off + ihl_len;
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if (iph + 1 > data_end)
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return 0;
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ihl_len += iph->ihl * 4;
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nexthdr = iph->protocol;
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} else if (nexthdr == IPPROTO_IPV6) {
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ip6h = data + nh_off + ihl_len;
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if (ip6h + 1 > data_end)
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return 0;
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ihl_len += sizeof(struct ipv6hdr);
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nexthdr = ip6h->nexthdr;
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}
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if (nexthdr == IPPROTO_TCP)
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return tcp(data, nh_off + ihl_len, data_end);
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else if (nexthdr == IPPROTO_UDP)
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return udp(data, nh_off + ihl_len, data_end);
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return 0;
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}
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struct vlan_hdr {
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uint16_t h_vlan_TCI;
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uint16_t h_vlan_encapsulated_proto;
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};
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SEC("varlen")
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int handle_ingress(struct __sk_buff *skb)
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{
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void *data = (void *)(long)skb->data;
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struct ethhdr *eth = data;
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void *data_end = (void *)(long)skb->data_end;
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uint64_t h_proto, nh_off;
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nh_off = sizeof(*eth);
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if (data + nh_off > data_end)
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return 0;
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h_proto = eth->h_proto;
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if (h_proto == ETH_P_8021Q || h_proto == ETH_P_8021AD) {
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struct vlan_hdr *vhdr;
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vhdr = data + nh_off;
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nh_off += sizeof(struct vlan_hdr);
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if (data + nh_off > data_end)
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return 0;
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h_proto = vhdr->h_vlan_encapsulated_proto;
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}
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if (h_proto == ETH_P_8021Q || h_proto == ETH_P_8021AD) {
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struct vlan_hdr *vhdr;
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vhdr = data + nh_off;
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nh_off += sizeof(struct vlan_hdr);
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if (data + nh_off > data_end)
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return 0;
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h_proto = vhdr->h_vlan_encapsulated_proto;
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}
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if (h_proto == htons(ETH_P_IP))
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return parse_ipv4(data, nh_off, data_end);
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else if (h_proto == htons(ETH_P_IPV6))
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return parse_ipv6(data, nh_off, data_end);
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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