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