include/net/netfilter/nf_conntrack_l3proto.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Copyright (C)2003,2004 USAGI/WIDE Project
   4  *
   5  * Header for use in defining a given L3 protocol for connection tracking.
   6  *
   7  * Author:
   8  *      Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
   9  *
  10  * Derived from include/netfilter_ipv4/ip_conntrack_protocol.h
  11  */
  12
  13 #ifndef _NF_CONNTRACK_L3PROTO_H
  14 #define _NF_CONNTRACK_L3PROTO_H
  15 #include <linux/netlink.h>
  16 #include <net/netlink.h>
  17 #include <linux/seq_file.h>
  18 #include <net/netfilter/nf_conntrack.h>
  19
  20 struct nf_conntrack_l3proto {
  21         /* L3 Protocol Family number. ex) PF_INET */
  22         u_int16_t l3proto;
  23
  24         /* size of tuple nlattr, fills a hole */
  25         u16 nla_size;
  26
  27         /*
  28          * Try to fill in the third arg: nhoff is offset of l3 proto
  29          * hdr.  Return true if possible.
  30          */
  31         bool (*pkt_to_tuple)(const struct sk_buff *skb, unsigned int nhoff,
  32                              struct nf_conntrack_tuple *tuple);
  33
  34         /*
  35          * Invert the per-proto part of the tuple: ie. turn xmit into reply.
  36          * Some packets can't be inverted: return 0 in that case.
  37          */
  38         bool (*invert_tuple)(struct nf_conntrack_tuple *inverse,
  39                              const struct nf_conntrack_tuple *orig);
  40
  41         /*
  42          * Called before tracking.
  43          *      *dataoff: offset of protocol header (TCP, UDP,...) in skb
  44          *      *protonum: protocol number
  45          */
  46         int (*get_l4proto)(const struct sk_buff *skb, unsigned int nhoff,
  47                            unsigned int *dataoff, u_int8_t *protonum);
  48
  49 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
  50         int (*tuple_to_nlattr)(struct sk_buff *skb,
  51                                const struct nf_conntrack_tuple *t);
  52         int (*nlattr_to_tuple)(struct nlattr *tb[],
  53                                struct nf_conntrack_tuple *t);
  54         const struct nla_policy *nla_policy;
  55 #endif
  56
  57         /* Called when netns wants to use connection tracking */
  58         int (*net_ns_get)(struct net *);
  59         void (*net_ns_put)(struct net *);
  60
  61         /* Module (if any) which this is connected to. */
  62         struct module *me;
  63 };
  64
  65 extern struct nf_conntrack_l3proto __rcu *nf_ct_l3protos[NFPROTO_NUMPROTO];
  66
  67 /* Protocol global registration. */
  68 int nf_ct_l3proto_register(const struct nf_conntrack_l3proto *proto);
  69 void nf_ct_l3proto_unregister(const struct nf_conntrack_l3proto *proto);
  70
  71 const struct nf_conntrack_l3proto *nf_ct_l3proto_find_get(u_int16_t l3proto);
  72
  73 /* Existing built-in protocols */
  74 extern struct nf_conntrack_l3proto nf_conntrack_l3proto_generic;
  75
  76 static inline struct nf_conntrack_l3proto *
  77 __nf_ct_l3proto_find(u_int16_t l3proto)
  78 {
  79         if (unlikely(l3proto >= NFPROTO_NUMPROTO))
  80                 return &nf_conntrack_l3proto_generic;
  81         return rcu_dereference(nf_ct_l3protos[l3proto]);
  82 }
  83
  84 #endif /*_NF_CONNTRACK_L3PROTO_H*/