src/patches/linux-3.2-codel/0000-net-introduce-skb_flow_dissect.patch

   1 From: Eric Dumazet <eric.dumazet@gmail.com>
   2 Date: Mon, 28 Nov 2011 05:22:18 +0000
   3 Subject: [PATCH 1/3] net: introduce skb_flow_dissect()
   4
   5 commit 0744dd00c1b1be99a25b62b1b48df440e82e57e0 upstream.
   6
   7 We use at least two flow dissectors in network stack, with known
   8 limitations and code duplication.
   9
  10 Introduce skb_flow_dissect() to factorize this, highly inspired from
  11 existing dissector from __skb_get_rxhash()
  12
  13 Note : We extensively use skb_header_pointer(), this permits us to not
  14 touch skb at all.
  15
  16 Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
  17 Signed-off-by: David S. Miller <davem@davemloft.net>
  18
  19 diff --git a/include/net/flow_keys.h b/include/net/flow_keys.h
  20 new file mode 100644
  21 index 0000000..e4cb285
  22 --- /dev/null
  23 +++ b/include/net/flow_keys.h
  24 @@ -0,0 +1,15 @@
  25 +#ifndef _NET_FLOW_KEYS_H
  26 +#define _NET_FLOW_KEYS_H
  27 +
  28 +struct flow_keys {
  29 +       __be32 src;
  30 +       __be32 dst;
  31 +       union {
  32 +               __be32 ports;
  33 +               __be16 port16[2];
  34 +       };
  35 +       u8 ip_proto;
  36 +};
  37 +
  38 +extern bool skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow);
  39 +#endif
  40 diff --git a/net/core/Makefile b/net/core/Makefile
  41 index 3606d40..c4ecc86 100644
  42 --- a/net/core/Makefile
  43 +++ b/net/core/Makefile
  44 @@ -3,7 +3,7 @@
  45  #
  46
  47  obj-y := sock.o request_sock.o skbuff.o iovec.o datagram.o stream.o scm.o \
  48 -        gen_stats.o gen_estimator.o net_namespace.o secure_seq.o
  49 +        gen_stats.o gen_estimator.o net_namespace.o secure_seq.o flow_dissector.o
  50
  51  obj-$(CONFIG_SYSCTL) += sysctl_net_core.o
  52
  53 diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
  54 new file mode 100644
  55 index 0000000..f0516d9
  56 --- /dev/null
  57 +++ b/net/core/flow_dissector.c
  58 @@ -0,0 +1,134 @@
  59 +#include <linux/skbuff.h>
  60 +#include <linux/ip.h>
  61 +#include <linux/ipv6.h>
  62 +#include <linux/if_vlan.h>
  63 +#include <net/ip.h>
  64 +#include <linux/if_tunnel.h>
  65 +#include <linux/if_pppox.h>
  66 +#include <linux/ppp_defs.h>
  67 +#include <net/flow_keys.h>
  68 +
  69 +
  70 +bool skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow)
  71 +{
  72 +       int poff, nhoff = skb_network_offset(skb);
  73 +       u8 ip_proto;
  74 +       __be16 proto = skb->protocol;
  75 +
  76 +       memset(flow, 0, sizeof(*flow));
  77 +
  78 +again:
  79 +       switch (proto) {
  80 +       case __constant_htons(ETH_P_IP): {
  81 +               const struct iphdr *iph;
  82 +               struct iphdr _iph;
  83 +ip:
  84 +               iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
  85 +               if (!iph)
  86 +                       return false;
  87 +
  88 +               if (ip_is_fragment(iph))
  89 +                       ip_proto = 0;
  90 +               else
  91 +                       ip_proto = iph->protocol;
  92 +               flow->src = iph->saddr;
  93 +               flow->dst = iph->daddr;
  94 +               nhoff += iph->ihl * 4;
  95 +               break;
  96 +       }
  97 +       case __constant_htons(ETH_P_IPV6): {
  98 +               const struct ipv6hdr *iph;
  99 +               struct ipv6hdr _iph;
 100 +ipv6:
 101 +               iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
 102 +               if (!iph)
 103 +                       return false;
 104 +
 105 +               ip_proto = iph->nexthdr;
 106 +               flow->src = iph->saddr.s6_addr32[3];
 107 +               flow->dst = iph->daddr.s6_addr32[3];
 108 +               nhoff += sizeof(struct ipv6hdr);
 109 +               break;
 110 +       }
 111 +       case __constant_htons(ETH_P_8021Q): {
 112 +               const struct vlan_hdr *vlan;
 113 +               struct vlan_hdr _vlan;
 114 +
 115 +               vlan = skb_header_pointer(skb, nhoff, sizeof(_vlan), &_vlan);
 116 +               if (!vlan)
 117 +                       return false;
 118 +
 119 +               proto = vlan->h_vlan_encapsulated_proto;
 120 +               nhoff += sizeof(*vlan);
 121 +               goto again;
 122 +       }
 123 +       case __constant_htons(ETH_P_PPP_SES): {
 124 +               struct {
 125 +                       struct pppoe_hdr hdr;
 126 +                       __be16 proto;
 127 +               } *hdr, _hdr;
 128 +               hdr = skb_header_pointer(skb, nhoff, sizeof(_hdr), &_hdr);
 129 +               if (!hdr)
 130 +                       return false;
 131 +               proto = hdr->proto;
 132 +               nhoff += PPPOE_SES_HLEN;
 133 +               switch (proto) {
 134 +               case __constant_htons(PPP_IP):
 135 +                       goto ip;
 136 +               case __constant_htons(PPP_IPV6):
 137 +                       goto ipv6;
 138 +               default:
 139 +                       return false;
 140 +               }
 141 +       }
 142 +       default:
 143 +               return false;
 144 +       }
 145 +
 146 +       switch (ip_proto) {
 147 +       case IPPROTO_GRE: {
 148 +               struct gre_hdr {
 149 +                       __be16 flags;
 150 +                       __be16 proto;
 151 +               } *hdr, _hdr;
 152 +
 153 +               hdr = skb_header_pointer(skb, nhoff, sizeof(_hdr), &_hdr);
 154 +               if (!hdr)
 155 +                       return false;
 156 +               /*
 157 +                * Only look inside GRE if version zero and no
 158 +                * routing
 159 +                */
 160 +               if (!(hdr->flags & (GRE_VERSION|GRE_ROUTING))) {
 161 +                       proto = hdr->proto;
 162 +                       nhoff += 4;
 163 +                       if (hdr->flags & GRE_CSUM)
 164 +                               nhoff += 4;
 165 +                       if (hdr->flags & GRE_KEY)
 166 +                               nhoff += 4;
 167 +                       if (hdr->flags & GRE_SEQ)
 168 +                               nhoff += 4;
 169 +                       goto again;
 170 +               }
 171 +               break;
 172 +       }
 173 +       case IPPROTO_IPIP:
 174 +               goto again;
 175 +       default:
 176 +               break;
 177 +       }
 178 +
 179 +       flow->ip_proto = ip_proto;
 180 +       poff = proto_ports_offset(ip_proto);
 181 +       if (poff >= 0) {
 182 +               __be32 *ports, _ports;
 183 +
 184 +               nhoff += poff;
 185 +               ports = skb_header_pointer(skb, nhoff, sizeof(_ports), &_ports);
 186 +               if (ports)
 187 +                       flow->ports = *ports;
 188 +       }
 189 +
 190 +       return true;
 191 +}
 192 +EXPORT_SYMBOL(skb_flow_dissect);
 193 --
 194 1.7.10
 195