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 "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_keys {
  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_keys 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_keys),
 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_keys 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";