| Alexei Starovoitov | 6882804 | 2017-03-30 21:45:41 -0700 | [diff] [blame] | 1 | /* Copyright (c) 2017 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 | #include <stddef.h> |
| Yonghong Song | 579f1d9 | 2017-05-17 15:18:05 -0700 | [diff] [blame] | 8 | #include <string.h> |
| Alexei Starovoitov | 6882804 | 2017-03-30 21:45:41 -0700 | [diff] [blame] | 9 | #include <linux/bpf.h> |
| 10 | #include <linux/if_ether.h> |
| 11 | #include <linux/if_packet.h> |
| 12 | #include <linux/ip.h> |
| 13 | #include <linux/ipv6.h> |
| 14 | #include <linux/in.h> |
| 15 | #include <linux/tcp.h> |
| 16 | #include <linux/pkt_cls.h> |
| 17 | #include "bpf_helpers.h" |
| David S. Miller | bc1bafb | 2017-05-01 12:43:49 -0700 | [diff] [blame] | 18 | #include "bpf_endian.h" |
| Alexei Starovoitov | 6882804 | 2017-03-30 21:45:41 -0700 | [diff] [blame] | 19 | |
| Alexei Starovoitov | 6882804 | 2017-03-30 21:45:41 -0700 | [diff] [blame] | 20 | #define barrier() __asm__ __volatile__("": : :"memory") |
| 21 | int _version SEC("version") = 1; |
| 22 | |
| 23 | SEC("test1") |
| 24 | int process(struct __sk_buff *skb) |
| 25 | { |
| 26 | void *data_end = (void *)(long)skb->data_end; |
| 27 | void *data = (void *)(long)skb->data; |
| 28 | struct ethhdr *eth = (struct ethhdr *)(data); |
| 29 | struct tcphdr *tcp = NULL; |
| 30 | __u8 proto = 255; |
| 31 | __u64 ihl_len; |
| 32 | |
| 33 | if (eth + 1 > data_end) |
| 34 | return TC_ACT_SHOT; |
| 35 | |
| Daniel Borkmann | 43bcf70 | 2017-04-27 01:39:34 +0200 | [diff] [blame] | 36 | if (eth->h_proto == bpf_htons(ETH_P_IP)) { |
| Alexei Starovoitov | 6882804 | 2017-03-30 21:45:41 -0700 | [diff] [blame] | 37 | struct iphdr *iph = (struct iphdr *)(eth + 1); |
| 38 | |
| 39 | if (iph + 1 > data_end) |
| 40 | return TC_ACT_SHOT; |
| 41 | ihl_len = iph->ihl * 4; |
| 42 | proto = iph->protocol; |
| 43 | tcp = (struct tcphdr *)((void *)(iph) + ihl_len); |
| Daniel Borkmann | 43bcf70 | 2017-04-27 01:39:34 +0200 | [diff] [blame] | 44 | } else if (eth->h_proto == bpf_htons(ETH_P_IPV6)) { |
| Alexei Starovoitov | 6882804 | 2017-03-30 21:45:41 -0700 | [diff] [blame] | 45 | struct ipv6hdr *ip6h = (struct ipv6hdr *)(eth + 1); |
| 46 | |
| 47 | if (ip6h + 1 > data_end) |
| 48 | return TC_ACT_SHOT; |
| 49 | ihl_len = sizeof(*ip6h); |
| 50 | proto = ip6h->nexthdr; |
| 51 | tcp = (struct tcphdr *)((void *)(ip6h) + ihl_len); |
| 52 | } |
| 53 | |
| 54 | if (tcp) { |
| 55 | if (((void *)(tcp) + 20) > data_end || proto != 6) |
| 56 | return TC_ACT_SHOT; |
| 57 | barrier(); /* to force ordering of checks */ |
| 58 | if (((void *)(tcp) + 18) > data_end) |
| 59 | return TC_ACT_SHOT; |
| 60 | if (tcp->urg_ptr == 123) |
| 61 | return TC_ACT_OK; |
| 62 | } |
| 63 | |
| 64 | return TC_ACT_UNSPEC; |
| 65 | } |
