samples/bpf/sockex3_kern.c

   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 <uapi/linux/in.h>
   9 #include <uapi/linux/if.h>
  10 #include <uapi/linux/if_ether.h>
  11 #include <uapi/linux/ip.h>
  12 #include <uapi/linux/ipv6.h>
  13 #include <uapi/linux/if_tunnel.h>
  14 #include <uapi/linux/mpls.h>
  15 #include <bpf/bpf_helpers.h>
  16 #include "bpf_legacy.h"
  17 #define IP_MF           0x2000
  18 #define IP_OFFSET       0x1FFF
  19
  20 #define PROG(F) SEC("socket/"__stringify(F)) int bpf_func_##F
  21
  22 struct {
  23         __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
  24         __uint(key_size, sizeof(u32));
  25         __uint(value_size, sizeof(u32));
  26         __uint(max_entries, 8);
  27 } jmp_table SEC(".maps");
  28
  29 #define PARSE_VLAN 1
  30 #define PARSE_MPLS 2
  31 #define PARSE_IP 3
  32 #define PARSE_IPV6 4
  33
  34 /* Protocol dispatch routine. It tail-calls next BPF program depending
  35  * on eth proto. Note, we could have used ...
  36  *
  37  *   bpf_tail_call(skb, &jmp_table, proto);
  38  *
  39  * ... but it would need large prog_array and cannot be optimised given
  40  * the map key is not static.
  41  */
  42 static inline void parse_eth_proto(struct __sk_buff *skb, u32 proto)
  43 {
  44         switch (proto) {
  45         case ETH_P_8021Q:
  46         case ETH_P_8021AD:
  47                 bpf_tail_call(skb, &jmp_table, PARSE_VLAN);
  48                 break;
  49         case ETH_P_MPLS_UC:
  50         case ETH_P_MPLS_MC:
  51                 bpf_tail_call(skb, &jmp_table, PARSE_MPLS);
  52                 break;
  53         case ETH_P_IP:
  54                 bpf_tail_call(skb, &jmp_table, PARSE_IP);
  55                 break;
  56         case ETH_P_IPV6:
  57                 bpf_tail_call(skb, &jmp_table, PARSE_IPV6);
  58                 break;
  59         }
  60 }
  61
  62 struct vlan_hdr {
  63         __be16 h_vlan_TCI;
  64         __be16 h_vlan_encapsulated_proto;
  65 };
  66
  67 struct flow_key_record {
  68         __be32 src;
  69         __be32 dst;
  70         union {
  71                 __be32 ports;
  72                 __be16 port16[2];
  73         };
  74         __u32 ip_proto;
  75 };
  76
  77 static inline int ip_is_fragment(struct __sk_buff *ctx, __u64 nhoff)
  78 {
  79         return load_half(ctx, nhoff + offsetof(struct iphdr, frag_off))
  80                 & (IP_MF | IP_OFFSET);
  81 }
  82
  83 static inline __u32 ipv6_addr_hash(struct __sk_buff *ctx, __u64 off)
  84 {
  85         __u64 w0 = load_word(ctx, off);
  86         __u64 w1 = load_word(ctx, off + 4);
  87         __u64 w2 = load_word(ctx, off + 8);
  88         __u64 w3 = load_word(ctx, off + 12);
  89
  90         return (__u32)(w0 ^ w1 ^ w2 ^ w3);
  91 }
  92
  93 struct globals {
  94         struct flow_key_record flow;
  95 };
  96
  97 struct {
  98         __uint(type, BPF_MAP_TYPE_ARRAY);
  99         __type(key, __u32);
 100         __type(value, struct globals);
 101         __uint(max_entries, 32);
 102 } percpu_map SEC(".maps");
 103
 104 /* user poor man's per_cpu until native support is ready */
 105 static struct globals *this_cpu_globals(void)
 106 {
 107         u32 key = bpf_get_smp_processor_id();
 108
 109         return bpf_map_lookup_elem(&percpu_map, &key);
 110 }
 111
 112 /* some simple stats for user space consumption */
 113 struct pair {
 114         __u64 packets;
 115         __u64 bytes;
 116 };
 117
 118 struct {
 119         __uint(type, BPF_MAP_TYPE_HASH);
 120         __type(key, struct flow_key_record);
 121         __type(value, struct pair);
 122         __uint(max_entries, 1024);
 123 } hash_map SEC(".maps");
 124
 125 static void update_stats(struct __sk_buff *skb, struct globals *g)
 126 {
 127         struct flow_key_record key = g->flow;
 128         struct pair *value;
 129
 130         value = bpf_map_lookup_elem(&hash_map, &key);
 131         if (value) {
 132                 __sync_fetch_and_add(&value->packets, 1);
 133                 __sync_fetch_and_add(&value->bytes, skb->len);
 134         } else {
 135                 struct pair val = {1, skb->len};
 136
 137                 bpf_map_update_elem(&hash_map, &key, &val, BPF_ANY);
 138         }
 139 }
 140
 141 static __always_inline void parse_ip_proto(struct __sk_buff *skb,
 142                                            struct globals *g, __u32 ip_proto)
 143 {
 144         __u32 nhoff = skb->cb[0];
 145         int poff;
 146
 147         switch (ip_proto) {
 148         case IPPROTO_GRE: {
 149                 struct gre_hdr {
 150                         __be16 flags;
 151                         __be16 proto;
 152                 };
 153
 154                 __u32 gre_flags = load_half(skb,
 155                                             nhoff + offsetof(struct gre_hdr, flags));
 156                 __u32 gre_proto = load_half(skb,
 157                                             nhoff + offsetof(struct gre_hdr, proto));
 158
 159                 if (gre_flags & (GRE_VERSION|GRE_ROUTING))
 160                         break;
 161
 162                 nhoff += 4;
 163                 if (gre_flags & GRE_CSUM)
 164                         nhoff += 4;
 165                 if (gre_flags & GRE_KEY)
 166                         nhoff += 4;
 167                 if (gre_flags & GRE_SEQ)
 168                         nhoff += 4;
 169
 170                 skb->cb[0] = nhoff;
 171                 parse_eth_proto(skb, gre_proto);
 172                 break;
 173         }
 174         case IPPROTO_IPIP:
 175                 parse_eth_proto(skb, ETH_P_IP);
 176                 break;
 177         case IPPROTO_IPV6:
 178                 parse_eth_proto(skb, ETH_P_IPV6);
 179                 break;
 180         case IPPROTO_TCP:
 181         case IPPROTO_UDP:
 182                 g->flow.ports = load_word(skb, nhoff);
 183         case IPPROTO_ICMP:
 184                 g->flow.ip_proto = ip_proto;
 185                 update_stats(skb, g);
 186                 break;
 187         default:
 188                 break;
 189         }
 190 }
 191
 192 PROG(PARSE_IP)(struct __sk_buff *skb)
 193 {
 194         struct globals *g = this_cpu_globals();
 195         __u32 nhoff, verlen, ip_proto;
 196
 197         if (!g)
 198                 return 0;
 199
 200         nhoff = skb->cb[0];
 201
 202         if (unlikely(ip_is_fragment(skb, nhoff)))
 203                 return 0;
 204
 205         ip_proto = load_byte(skb, nhoff + offsetof(struct iphdr, protocol));
 206
 207         if (ip_proto != IPPROTO_GRE) {
 208                 g->flow.src = load_word(skb, nhoff + offsetof(struct iphdr, saddr));
 209                 g->flow.dst = load_word(skb, nhoff + offsetof(struct iphdr, daddr));
 210         }
 211
 212         verlen = load_byte(skb, nhoff + 0/*offsetof(struct iphdr, ihl)*/);
 213         nhoff += (verlen & 0xF) << 2;
 214
 215         skb->cb[0] = nhoff;
 216         parse_ip_proto(skb, g, ip_proto);
 217         return 0;
 218 }
 219
 220 PROG(PARSE_IPV6)(struct __sk_buff *skb)
 221 {
 222         struct globals *g = this_cpu_globals();
 223         __u32 nhoff, ip_proto;
 224
 225         if (!g)
 226                 return 0;
 227
 228         nhoff = skb->cb[0];
 229
 230         ip_proto = load_byte(skb,
 231                              nhoff + offsetof(struct ipv6hdr, nexthdr));
 232         g->flow.src = ipv6_addr_hash(skb,
 233                                      nhoff + offsetof(struct ipv6hdr, saddr));
 234         g->flow.dst = ipv6_addr_hash(skb,
 235                                      nhoff + offsetof(struct ipv6hdr, daddr));
 236         nhoff += sizeof(struct ipv6hdr);
 237
 238         skb->cb[0] = nhoff;
 239         parse_ip_proto(skb, g, ip_proto);
 240         return 0;
 241 }
 242
 243 PROG(PARSE_VLAN)(struct __sk_buff *skb)
 244 {
 245         __u32 nhoff, proto;
 246
 247         nhoff = skb->cb[0];
 248
 249         proto = load_half(skb, nhoff + offsetof(struct vlan_hdr,
 250                                                 h_vlan_encapsulated_proto));
 251         nhoff += sizeof(struct vlan_hdr);
 252         skb->cb[0] = nhoff;
 253
 254         parse_eth_proto(skb, proto);
 255
 256         return 0;
 257 }
 258
 259 PROG(PARSE_MPLS)(struct __sk_buff *skb)
 260 {
 261         __u32 nhoff, label;
 262
 263         nhoff = skb->cb[0];
 264
 265         label = load_word(skb, nhoff);
 266         nhoff += sizeof(struct mpls_label);
 267         skb->cb[0] = nhoff;
 268
 269         if (label & MPLS_LS_S_MASK) {
 270                 __u8 verlen = load_byte(skb, nhoff);
 271                 if ((verlen & 0xF0) == 4)
 272                         parse_eth_proto(skb, ETH_P_IP);
 273                 else
 274                         parse_eth_proto(skb, ETH_P_IPV6);
 275         } else {
 276                 parse_eth_proto(skb, ETH_P_MPLS_UC);
 277         }
 278
 279         return 0;
 280 }
 281
 282 SEC("socket/0")
 283 int main_prog(struct __sk_buff *skb)
 284 {
 285         __u32 nhoff = ETH_HLEN;
 286         __u32 proto = load_half(skb, 12);
 287
 288         skb->cb[0] = nhoff;
 289         parse_eth_proto(skb, proto);
 290         return 0;
 291 }
 292
 293 char _license[] SEC("license") = "GPL";