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65d472fb AS |
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 | */ | |
96a8eb1e | 7 | #define KBUILD_MODNAME "foo" |
65d472fb AS |
8 | #include <linux/if_ether.h> |
9 | #include <linux/ip.h> | |
10 | #include <linux/ipv6.h> | |
11 | #include <linux/in.h> | |
12 | #include <linux/tcp.h> | |
13 | #include <linux/udp.h> | |
14 | #include <uapi/linux/bpf.h> | |
15 | #include <net/ip.h> | |
16 | #include "bpf_helpers.h" | |
17 | ||
18 | #define DEFAULT_PKTGEN_UDP_PORT 9 | |
19 | #define DEBUG 0 | |
20 | ||
21 | static int tcp(void *data, uint64_t tp_off, void *data_end) | |
22 | { | |
23 | struct tcphdr *tcp = data + tp_off; | |
24 | ||
25 | if (tcp + 1 > data_end) | |
26 | return 0; | |
27 | if (tcp->dest == htons(80) || tcp->source == htons(80)) | |
28 | return TC_ACT_SHOT; | |
29 | return 0; | |
30 | } | |
31 | ||
32 | static int udp(void *data, uint64_t tp_off, void *data_end) | |
33 | { | |
34 | struct udphdr *udp = data + tp_off; | |
35 | ||
36 | if (udp + 1 > data_end) | |
37 | return 0; | |
38 | if (udp->dest == htons(DEFAULT_PKTGEN_UDP_PORT) || | |
39 | udp->source == htons(DEFAULT_PKTGEN_UDP_PORT)) { | |
40 | if (DEBUG) { | |
41 | char fmt[] = "udp port 9 indeed\n"; | |
42 | ||
43 | bpf_trace_printk(fmt, sizeof(fmt)); | |
44 | } | |
45 | return TC_ACT_SHOT; | |
46 | } | |
47 | return 0; | |
48 | } | |
49 | ||
50 | static int parse_ipv4(void *data, uint64_t nh_off, void *data_end) | |
51 | { | |
52 | struct iphdr *iph; | |
53 | uint64_t ihl_len; | |
54 | ||
55 | iph = data + nh_off; | |
56 | if (iph + 1 > data_end) | |
57 | return 0; | |
58 | ||
59 | if (ip_is_fragment(iph)) | |
60 | return 0; | |
61 | ihl_len = iph->ihl * 4; | |
62 | ||
63 | if (iph->protocol == IPPROTO_IPIP) { | |
64 | iph = data + nh_off + ihl_len; | |
65 | if (iph + 1 > data_end) | |
66 | return 0; | |
67 | ihl_len += iph->ihl * 4; | |
68 | } | |
69 | ||
70 | if (iph->protocol == IPPROTO_TCP) | |
71 | return tcp(data, nh_off + ihl_len, data_end); | |
72 | else if (iph->protocol == IPPROTO_UDP) | |
73 | return udp(data, nh_off + ihl_len, data_end); | |
74 | return 0; | |
75 | } | |
76 | ||
77 | static int parse_ipv6(void *data, uint64_t nh_off, void *data_end) | |
78 | { | |
79 | struct ipv6hdr *ip6h; | |
80 | struct iphdr *iph; | |
81 | uint64_t ihl_len = sizeof(struct ipv6hdr); | |
82 | uint64_t nexthdr; | |
83 | ||
84 | ip6h = data + nh_off; | |
85 | if (ip6h + 1 > data_end) | |
86 | return 0; | |
87 | ||
88 | nexthdr = ip6h->nexthdr; | |
89 | ||
90 | if (nexthdr == IPPROTO_IPIP) { | |
91 | iph = data + nh_off + ihl_len; | |
92 | if (iph + 1 > data_end) | |
93 | return 0; | |
94 | ihl_len += iph->ihl * 4; | |
95 | nexthdr = iph->protocol; | |
96 | } else if (nexthdr == IPPROTO_IPV6) { | |
97 | ip6h = data + nh_off + ihl_len; | |
98 | if (ip6h + 1 > data_end) | |
99 | return 0; | |
100 | ihl_len += sizeof(struct ipv6hdr); | |
101 | nexthdr = ip6h->nexthdr; | |
102 | } | |
103 | ||
104 | if (nexthdr == IPPROTO_TCP) | |
105 | return tcp(data, nh_off + ihl_len, data_end); | |
106 | else if (nexthdr == IPPROTO_UDP) | |
107 | return udp(data, nh_off + ihl_len, data_end); | |
108 | return 0; | |
109 | } | |
110 | ||
111 | struct vlan_hdr { | |
112 | uint16_t h_vlan_TCI; | |
113 | uint16_t h_vlan_encapsulated_proto; | |
114 | }; | |
115 | ||
116 | SEC("varlen") | |
117 | int handle_ingress(struct __sk_buff *skb) | |
118 | { | |
119 | void *data = (void *)(long)skb->data; | |
120 | struct ethhdr *eth = data; | |
121 | void *data_end = (void *)(long)skb->data_end; | |
122 | uint64_t h_proto, nh_off; | |
123 | ||
124 | nh_off = sizeof(*eth); | |
125 | if (data + nh_off > data_end) | |
126 | return 0; | |
127 | ||
128 | h_proto = eth->h_proto; | |
129 | ||
130 | if (h_proto == ETH_P_8021Q || h_proto == ETH_P_8021AD) { | |
131 | struct vlan_hdr *vhdr; | |
132 | ||
133 | vhdr = data + nh_off; | |
134 | nh_off += sizeof(struct vlan_hdr); | |
135 | if (data + nh_off > data_end) | |
136 | return 0; | |
137 | h_proto = vhdr->h_vlan_encapsulated_proto; | |
138 | } | |
139 | if (h_proto == ETH_P_8021Q || h_proto == ETH_P_8021AD) { | |
140 | struct vlan_hdr *vhdr; | |
141 | ||
142 | vhdr = data + nh_off; | |
143 | nh_off += sizeof(struct vlan_hdr); | |
144 | if (data + nh_off > data_end) | |
145 | return 0; | |
146 | h_proto = vhdr->h_vlan_encapsulated_proto; | |
147 | } | |
148 | if (h_proto == htons(ETH_P_IP)) | |
149 | return parse_ipv4(data, nh_off, data_end); | |
150 | else if (h_proto == htons(ETH_P_IPV6)) | |
151 | return parse_ipv6(data, nh_off, data_end); | |
152 | return 0; | |
153 | } | |
154 | char _license[] SEC("license") = "GPL"; |