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 <linux/if_ether.h> |
9 | #include <linux/if_vlan.h> |
10 | #include <linux/ip.h> |
11 | #include <linux/ipv6.h> |
12 | #include <linux/in.h> |
13 | #include <linux/tcp.h> |
14 | #include <linux/udp.h> |
15 | #include <uapi/linux/bpf.h> |
16 | #include <net/ip.h> |
17 | #include <bpf/bpf_helpers.h> |
18 | |
19 | #define DEFAULT_PKTGEN_UDP_PORT 9 |
20 | #define DEBUG 0 |
21 | |
22 | static int tcp(void *data, uint64_t tp_off, void *data_end) |
23 | { |
24 | struct tcphdr *tcp = data + tp_off; |
25 | |
26 | if (tcp + 1 > data_end) |
27 | return 0; |
28 | if (tcp->dest == htons(80) || tcp->source == htons(80)) |
29 | return TC_ACT_SHOT; |
30 | return 0; |
31 | } |
32 | |
33 | static int udp(void *data, uint64_t tp_off, void *data_end) |
34 | { |
35 | struct udphdr *udp = data + tp_off; |
36 | |
37 | if (udp + 1 > data_end) |
38 | return 0; |
39 | if (udp->dest == htons(DEFAULT_PKTGEN_UDP_PORT) || |
40 | udp->source == htons(DEFAULT_PKTGEN_UDP_PORT)) { |
41 | if (DEBUG) { |
42 | char fmt[] = "udp port 9 indeed\n" ; |
43 | |
44 | bpf_trace_printk(fmt, sizeof(fmt)); |
45 | } |
46 | return TC_ACT_SHOT; |
47 | } |
48 | return 0; |
49 | } |
50 | |
51 | static int parse_ipv4(void *data, uint64_t nh_off, void *data_end) |
52 | { |
53 | struct iphdr *iph; |
54 | uint64_t ihl_len; |
55 | |
56 | iph = data + nh_off; |
57 | if (iph + 1 > data_end) |
58 | return 0; |
59 | |
60 | if (ip_is_fragment(iph)) |
61 | return 0; |
62 | ihl_len = iph->ihl * 4; |
63 | |
64 | if (iph->protocol == IPPROTO_IPIP) { |
65 | iph = data + nh_off + ihl_len; |
66 | if (iph + 1 > data_end) |
67 | return 0; |
68 | ihl_len += iph->ihl * 4; |
69 | } |
70 | |
71 | if (iph->protocol == IPPROTO_TCP) |
72 | return tcp(data, nh_off + ihl_len, data_end); |
73 | else if (iph->protocol == IPPROTO_UDP) |
74 | return udp(data, nh_off + ihl_len, data_end); |
75 | return 0; |
76 | } |
77 | |
78 | static int parse_ipv6(void *data, uint64_t nh_off, void *data_end) |
79 | { |
80 | struct ipv6hdr *ip6h; |
81 | struct iphdr *iph; |
82 | uint64_t ihl_len = sizeof(struct ipv6hdr); |
83 | uint64_t nexthdr; |
84 | |
85 | ip6h = data + nh_off; |
86 | if (ip6h + 1 > data_end) |
87 | return 0; |
88 | |
89 | nexthdr = ip6h->nexthdr; |
90 | |
91 | if (nexthdr == IPPROTO_IPIP) { |
92 | iph = data + nh_off + ihl_len; |
93 | if (iph + 1 > data_end) |
94 | return 0; |
95 | ihl_len += iph->ihl * 4; |
96 | nexthdr = iph->protocol; |
97 | } else if (nexthdr == IPPROTO_IPV6) { |
98 | ip6h = data + nh_off + ihl_len; |
99 | if (ip6h + 1 > data_end) |
100 | return 0; |
101 | ihl_len += sizeof(struct ipv6hdr); |
102 | nexthdr = ip6h->nexthdr; |
103 | } |
104 | |
105 | if (nexthdr == IPPROTO_TCP) |
106 | return tcp(data, nh_off + ihl_len, data_end); |
107 | else if (nexthdr == IPPROTO_UDP) |
108 | return udp(data, nh_off + ihl_len, data_end); |
109 | return 0; |
110 | } |
111 | |
112 | SEC("varlen" ) |
113 | int handle_ingress(struct __sk_buff *skb) |
114 | { |
115 | void *data = (void *)(long)skb->data; |
116 | struct ethhdr *eth = data; |
117 | void *data_end = (void *)(long)skb->data_end; |
118 | uint64_t h_proto, nh_off; |
119 | |
120 | nh_off = sizeof(*eth); |
121 | if (data + nh_off > data_end) |
122 | return 0; |
123 | |
124 | h_proto = eth->h_proto; |
125 | |
126 | if (h_proto == ETH_P_8021Q || h_proto == ETH_P_8021AD) { |
127 | struct vlan_hdr *vhdr; |
128 | |
129 | vhdr = data + nh_off; |
130 | nh_off += sizeof(struct vlan_hdr); |
131 | if (data + nh_off > data_end) |
132 | return 0; |
133 | h_proto = vhdr->h_vlan_encapsulated_proto; |
134 | } |
135 | if (h_proto == ETH_P_8021Q || h_proto == ETH_P_8021AD) { |
136 | struct vlan_hdr *vhdr; |
137 | |
138 | vhdr = data + nh_off; |
139 | nh_off += sizeof(struct vlan_hdr); |
140 | if (data + nh_off > data_end) |
141 | return 0; |
142 | h_proto = vhdr->h_vlan_encapsulated_proto; |
143 | } |
144 | if (h_proto == htons(ETH_P_IP)) |
145 | return parse_ipv4(data, nh_off, data_end); |
146 | else if (h_proto == htons(ETH_P_IPV6)) |
147 | return parse_ipv6(data, nh_off, data_end); |
148 | return 0; |
149 | } |
150 | char _license[] SEC("license" ) = "GPL" ; |
151 | |