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Linux/samples/bpf/sockex3_kern.c

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  1 /* Copyright (c) 2015 PLUMgrid, http://plumgrid.com
  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 <uapi/linux/bpf.h>
  8 #include "bpf_helpers.h"
  9 #include <uapi/linux/in.h>
 10 #include <uapi/linux/if.h>
 11 #include <uapi/linux/if_ether.h>
 12 #include <uapi/linux/ip.h>
 13 #include <uapi/linux/ipv6.h>
 14 #include <uapi/linux/if_tunnel.h>
 15 #include <uapi/linux/mpls.h>
 16 #define IP_MF           0x2000
 17 #define IP_OFFSET       0x1FFF
 18 
 19 #define PROG(F) SEC("socket/"__stringify(F)) int bpf_func_##F
 20 
 21 struct bpf_map_def SEC("maps") jmp_table = {
 22         .type = BPF_MAP_TYPE_PROG_ARRAY,
 23         .key_size = sizeof(u32),
 24         .value_size = sizeof(u32),
 25         .max_entries = 8,
 26 };
 27 
 28 #define PARSE_VLAN 1
 29 #define PARSE_MPLS 2
 30 #define PARSE_IP 3
 31 #define PARSE_IPV6 4
 32 
 33 /* protocol dispatch routine.
 34  * It tail-calls next BPF program depending on eth proto
 35  * Note, we could have used:
 36  * bpf_tail_call(skb, &jmp_table, proto);
 37  * but it would need large prog_array
 38  */
 39 static inline void parse_eth_proto(struct __sk_buff *skb, u32 proto)
 40 {
 41         switch (proto) {
 42         case ETH_P_8021Q:
 43         case ETH_P_8021AD:
 44                 bpf_tail_call(skb, &jmp_table, PARSE_VLAN);
 45                 break;
 46         case ETH_P_MPLS_UC:
 47         case ETH_P_MPLS_MC:
 48                 bpf_tail_call(skb, &jmp_table, PARSE_MPLS);
 49                 break;
 50         case ETH_P_IP:
 51                 bpf_tail_call(skb, &jmp_table, PARSE_IP);
 52                 break;
 53         case ETH_P_IPV6:
 54                 bpf_tail_call(skb, &jmp_table, PARSE_IPV6);
 55                 break;
 56         }
 57 }
 58 
 59 struct vlan_hdr {
 60         __be16 h_vlan_TCI;
 61         __be16 h_vlan_encapsulated_proto;
 62 };
 63 
 64 struct flow_key_record {
 65         __be32 src;
 66         __be32 dst;
 67         union {
 68                 __be32 ports;
 69                 __be16 port16[2];
 70         };
 71         __u32 ip_proto;
 72 };
 73 
 74 static inline int ip_is_fragment(struct __sk_buff *ctx, __u64 nhoff)
 75 {
 76         return load_half(ctx, nhoff + offsetof(struct iphdr, frag_off))
 77                 & (IP_MF | IP_OFFSET);
 78 }
 79 
 80 static inline __u32 ipv6_addr_hash(struct __sk_buff *ctx, __u64 off)
 81 {
 82         __u64 w0 = load_word(ctx, off);
 83         __u64 w1 = load_word(ctx, off + 4);
 84         __u64 w2 = load_word(ctx, off + 8);
 85         __u64 w3 = load_word(ctx, off + 12);
 86 
 87         return (__u32)(w0 ^ w1 ^ w2 ^ w3);
 88 }
 89 
 90 struct globals {
 91         struct flow_key_record flow;
 92 };
 93 
 94 struct bpf_map_def SEC("maps") percpu_map = {
 95         .type = BPF_MAP_TYPE_ARRAY,
 96         .key_size = sizeof(__u32),
 97         .value_size = sizeof(struct globals),
 98         .max_entries = 32,
 99 };
100 
101 /* user poor man's per_cpu until native support is ready */
102 static struct globals *this_cpu_globals(void)
103 {
104         u32 key = bpf_get_smp_processor_id();
105 
106         return bpf_map_lookup_elem(&percpu_map, &key);
107 }
108 
109 /* some simple stats for user space consumption */
110 struct pair {
111         __u64 packets;
112         __u64 bytes;
113 };
114 
115 struct bpf_map_def SEC("maps") hash_map = {
116         .type = BPF_MAP_TYPE_HASH,
117         .key_size = sizeof(struct flow_key_record),
118         .value_size = sizeof(struct pair),
119         .max_entries = 1024,
120 };
121 
122 static void update_stats(struct __sk_buff *skb, struct globals *g)
123 {
124         struct flow_key_record key = g->flow;
125         struct pair *value;
126 
127         value = bpf_map_lookup_elem(&hash_map, &key);
128         if (value) {
129                 __sync_fetch_and_add(&value->packets, 1);
130                 __sync_fetch_and_add(&value->bytes, skb->len);
131         } else {
132                 struct pair val = {1, skb->len};
133 
134                 bpf_map_update_elem(&hash_map, &key, &val, BPF_ANY);
135         }
136 }
137 
138 static __always_inline void parse_ip_proto(struct __sk_buff *skb,
139                                            struct globals *g, __u32 ip_proto)
140 {
141         __u32 nhoff = skb->cb[0];
142         int poff;
143 
144         switch (ip_proto) {
145         case IPPROTO_GRE: {
146                 struct gre_hdr {
147                         __be16 flags;
148                         __be16 proto;
149                 };
150 
151                 __u32 gre_flags = load_half(skb,
152                                             nhoff + offsetof(struct gre_hdr, flags));
153                 __u32 gre_proto = load_half(skb,
154                                             nhoff + offsetof(struct gre_hdr, proto));
155 
156                 if (gre_flags & (GRE_VERSION|GRE_ROUTING))
157                         break;
158 
159                 nhoff += 4;
160                 if (gre_flags & GRE_CSUM)
161                         nhoff += 4;
162                 if (gre_flags & GRE_KEY)
163                         nhoff += 4;
164                 if (gre_flags & GRE_SEQ)
165                         nhoff += 4;
166 
167                 skb->cb[0] = nhoff;
168                 parse_eth_proto(skb, gre_proto);
169                 break;
170         }
171         case IPPROTO_IPIP:
172                 parse_eth_proto(skb, ETH_P_IP);
173                 break;
174         case IPPROTO_IPV6:
175                 parse_eth_proto(skb, ETH_P_IPV6);
176                 break;
177         case IPPROTO_TCP:
178         case IPPROTO_UDP:
179                 g->flow.ports = load_word(skb, nhoff);
180         case IPPROTO_ICMP:
181                 g->flow.ip_proto = ip_proto;
182                 update_stats(skb, g);
183                 break;
184         default:
185                 break;
186         }
187 }
188 
189 PROG(PARSE_IP)(struct __sk_buff *skb)
190 {
191         struct globals *g = this_cpu_globals();
192         __u32 nhoff, verlen, ip_proto;
193 
194         if (!g)
195                 return 0;
196 
197         nhoff = skb->cb[0];
198 
199         if (unlikely(ip_is_fragment(skb, nhoff)))
200                 return 0;
201 
202         ip_proto = load_byte(skb, nhoff + offsetof(struct iphdr, protocol));
203 
204         if (ip_proto != IPPROTO_GRE) {
205                 g->flow.src = load_word(skb, nhoff + offsetof(struct iphdr, saddr));
206                 g->flow.dst = load_word(skb, nhoff + offsetof(struct iphdr, daddr));
207         }
208 
209         verlen = load_byte(skb, nhoff + 0/*offsetof(struct iphdr, ihl)*/);
210         nhoff += (verlen & 0xF) << 2;
211 
212         skb->cb[0] = nhoff;
213         parse_ip_proto(skb, g, ip_proto);
214         return 0;
215 }
216 
217 PROG(PARSE_IPV6)(struct __sk_buff *skb)
218 {
219         struct globals *g = this_cpu_globals();
220         __u32 nhoff, ip_proto;
221 
222         if (!g)
223                 return 0;
224 
225         nhoff = skb->cb[0];
226 
227         ip_proto = load_byte(skb,
228                              nhoff + offsetof(struct ipv6hdr, nexthdr));
229         g->flow.src = ipv6_addr_hash(skb,
230                                      nhoff + offsetof(struct ipv6hdr, saddr));
231         g->flow.dst = ipv6_addr_hash(skb,
232                                      nhoff + offsetof(struct ipv6hdr, daddr));
233         nhoff += sizeof(struct ipv6hdr);
234 
235         skb->cb[0] = nhoff;
236         parse_ip_proto(skb, g, ip_proto);
237         return 0;
238 }
239 
240 PROG(PARSE_VLAN)(struct __sk_buff *skb)
241 {
242         __u32 nhoff, proto;
243 
244         nhoff = skb->cb[0];
245 
246         proto = load_half(skb, nhoff + offsetof(struct vlan_hdr,
247                                                 h_vlan_encapsulated_proto));
248         nhoff += sizeof(struct vlan_hdr);
249         skb->cb[0] = nhoff;
250 
251         parse_eth_proto(skb, proto);
252 
253         return 0;
254 }
255 
256 PROG(PARSE_MPLS)(struct __sk_buff *skb)
257 {
258         __u32 nhoff, label;
259 
260         nhoff = skb->cb[0];
261 
262         label = load_word(skb, nhoff);
263         nhoff += sizeof(struct mpls_label);
264         skb->cb[0] = nhoff;
265 
266         if (label & MPLS_LS_S_MASK) {
267                 __u8 verlen = load_byte(skb, nhoff);
268                 if ((verlen & 0xF0) == 4)
269                         parse_eth_proto(skb, ETH_P_IP);
270                 else
271                         parse_eth_proto(skb, ETH_P_IPV6);
272         } else {
273                 parse_eth_proto(skb, ETH_P_MPLS_UC);
274         }
275 
276         return 0;
277 }
278 
279 SEC("socket/0")
280 int main_prog(struct __sk_buff *skb)
281 {
282         __u32 nhoff = ETH_HLEN;
283         __u32 proto = load_half(skb, 12);
284 
285         skb->cb[0] = nhoff;
286         parse_eth_proto(skb, proto);
287         return 0;
288 }
289 
290 char _license[] SEC("license") = "GPL";
291 

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