1 /* Copyright (c) 2016 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 #define KBUILD_MODNAME "foo" 8 #include "vmlinux.h" 9 #include "net_shared.h" 10 #include <bpf/bpf_helpers.h> 11 12 /* copy of 'struct ethhdr' without __packed */ 13 struct eth_hdr { 14 unsigned char h_dest[ETH_ALEN]; 15 unsigned char h_source[ETH_ALEN]; 16 unsigned short h_proto; 17 }; 18 19 struct { 20 __uint(type, BPF_MAP_TYPE_CGROUP_ARRAY); 21 __type(key, u32); 22 __type(value, u32); 23 __uint(pinning, LIBBPF_PIN_BY_NAME); 24 __uint(max_entries, 1); 25 } test_cgrp2_array_pin SEC(".maps"); 26 27 SEC("filter") 28 int handle_egress(struct __sk_buff *skb) 29 { 30 void *data = (void *)(long)skb->data; 31 struct eth_hdr *eth = data; 32 struct ipv6hdr *ip6h = data + sizeof(*eth); 33 void *data_end = (void *)(long)skb->data_end; 34 char dont_care_msg[] = "dont care %04x %d\n"; 35 char pass_msg[] = "pass\n"; 36 char reject_msg[] = "reject\n"; 37 38 /* single length check */ 39 if (data + sizeof(*eth) + sizeof(*ip6h) > data_end) 40 return TC_ACT_OK; 41 42 if (eth->h_proto != bpf_htons(ETH_P_IPV6) || 43 ip6h->nexthdr != IPPROTO_ICMPV6) { 44 bpf_trace_printk(dont_care_msg, sizeof(dont_care_msg), 45 eth->h_proto, ip6h->nexthdr); 46 return TC_ACT_OK; 47 } else if (bpf_skb_under_cgroup(skb, &test_cgrp2_array_pin, 0) != 1) { 48 bpf_trace_printk(pass_msg, sizeof(pass_msg)); 49 return TC_ACT_OK; 50 } else { 51 bpf_trace_printk(reject_msg, sizeof(reject_msg)); 52 return TC_ACT_SHOT; 53 } 54 } 55 56 char _license[] SEC("license") = "GPL"; 57