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gerrit-public.fairphone.software / kernel / msm-4.9 / 0ab11d8ea46fd6faf67df4461c795091429a1496 / . / samples / bpf / parse_varlen.c
blob: edab34dce79b3794b010ca4138ef969d13c68535 [file] [log] [blame]
Alexei Starovoitov65d472f2016-05-05 19:49:14 -0700[diff] [blame]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
20static 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
31static 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
49static 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
76static 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
110struct vlan_hdr {
111 uint16_t h_vlan_TCI;
112 uint16_t h_vlan_encapsulated_proto;
113};
114
115SEC("varlen")
116int 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}
153char _license[] SEC("license") = "GPL";