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/bpf_helpers.h> 10 11 struct { 12 __uint(type, MAP_TYPE); 13 __uint(max_entries, 32); 14 __uint(map_flags, 0); 15 __uint(key_size, 0); 16 __uint(value_size, sizeof(__u32)); 17 } map_in SEC(".maps"); 18 19 struct { 20 __uint(type, MAP_TYPE); 21 __uint(max_entries, 32); 22 __uint(map_flags, 0); 23 __uint(key_size, 0); 24 __uint(value_size, sizeof(__u32)); 25 } map_out SEC(".maps"); 26 27 SEC("tc") 28 int _test(struct __sk_buff *skb) 29 { 30 void *data_end = (void *)(long)skb->data_end; 31 void *data = (void *)(long)skb->data; 32 struct ethhdr *eth = (struct ethhdr *)(data); 33 __u32 value; 34 int err; 35 36 if (eth + 1 > data_end) 37 return TC_ACT_SHOT; 38 39 struct iphdr *iph = (struct iphdr *)(eth + 1); 40 41 if (iph + 1 > data_end) 42 return TC_ACT_SHOT; 43 44 err = bpf_map_pop_elem(&map_in, &value); 45 if (err) 46 return TC_ACT_SHOT; 47 48 iph->daddr = value; 49 50 err = bpf_map_push_elem(&map_out, &iph->saddr, 0); 51 if (err) 52 return TC_ACT_SHOT; 53 54 return TC_ACT_OK; 55 } 56 57 char _license[] SEC("license") = "GPL"; 58