1 /* SPDX-License-Identifier: GPL-2.0 */ 2 // Copyright (c) 2018 Politecnico di Torino 3 #include <stddef.h> 4 #include <string.h> 5 #include <linux/bpf.h> 6 #include <linux/if_ether.h> 7 #include <linux/ip.h> 8 #include <linux/pkt_cls.h> 9 #include "bpf_helpers.h" 10 11 int _version SEC("version") = 1; 12 13 struct { 14 __uint(type, MAP_TYPE); 15 __uint(max_entries, 32); 16 __uint(map_flags, 0); 17 __uint(key_size, 0); 18 __uint(value_size, sizeof(__u32)); 19 } map_in SEC(".maps"); 20 21 struct { 22 __uint(type, MAP_TYPE); 23 __uint(max_entries, 32); 24 __uint(map_flags, 0); 25 __uint(key_size, 0); 26 __uint(value_size, sizeof(__u32)); 27 } map_out SEC(".maps"); 28 29 SEC("test") 30 int _test(struct __sk_buff *skb) 31 { 32 void *data_end = (void *)(long)skb->data_end; 33 void *data = (void *)(long)skb->data; 34 struct ethhdr *eth = (struct ethhdr *)(data); 35 __u32 value; 36 int err; 37 38 if (eth + 1 > data_end) 39 return TC_ACT_SHOT; 40 41 struct iphdr *iph = (struct iphdr *)(eth + 1); 42 43 if (iph + 1 > data_end) 44 return TC_ACT_SHOT; 45 46 err = bpf_map_pop_elem(&map_in, &value); 47 if (err) 48 return TC_ACT_SHOT; 49 50 iph->daddr = value; 51 52 err = bpf_map_push_elem(&map_out, &iph->saddr, 0); 53 if (err) 54 return TC_ACT_SHOT; 55 56 return TC_ACT_OK; 57 } 58 59 char _license[] SEC("license") = "GPL"; 60