LXR linux/include/net/netfilter/nf_conntrack

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 * connection tracking helpers.
   4 *
   5 * 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
   6 *      - generalize L3 protocol dependent part.
   7 *
   8 * Derived from include/linux/netfiter_ipv4/ip_conntrack_helper.h
   9 */
  10
  11#ifndef _NF_CONNTRACK_HELPER_H
  12#define _NF_CONNTRACK_HELPER_H
  13#include <linux/refcount.h>
  14#include <net/netfilter/nf_conntrack.h>
  15#include <net/netfilter/nf_conntrack_extend.h>
  16#include <net/netfilter/nf_conntrack_expect.h>
  17
  18struct module;
  19
  20enum nf_ct_helper_flags {
  21        NF_CT_HELPER_F_USERSPACE        = (1 << 0),
  22        NF_CT_HELPER_F_CONFIGURED       = (1 << 1),
  23};
  24
  25#define NF_CT_HELPER_NAME_LEN   16
  26
  27struct nf_conntrack_helper {
  28        struct hlist_node hnode;        /* Internal use. */
  29
  30        char name[NF_CT_HELPER_NAME_LEN]; /* name of the module */
  31        refcount_t refcnt;
  32        struct module *me;              /* pointer to self */
  33        const struct nf_conntrack_expect_policy *expect_policy;
  34
  35        /* Tuple of things we will help (compared against server response) */
  36        struct nf_conntrack_tuple tuple;
  37
  38        /* Function to call when data passes; return verdict, or -1 to
  39           invalidate. */
  40        int (*help)(struct sk_buff *skb,
  41                    unsigned int protoff,
  42                    struct nf_conn *ct,
  43                    enum ip_conntrack_info conntrackinfo);
  44
  45        void (*destroy)(struct nf_conn *ct);
  46
  47        int (*from_nlattr)(struct nlattr *attr, struct nf_conn *ct);
  48        int (*to_nlattr)(struct sk_buff *skb, const struct nf_conn *ct);
  49        unsigned int expect_class_max;
  50
  51        unsigned int flags;
  52
  53        /* For user-space helpers: */
  54        unsigned int queue_num;
  55        /* length of userspace private data stored in nf_conn_help->data */
  56        u16 data_len;
  57};
  58
  59/* Must be kept in sync with the classes defined by helpers */
  60#define NF_CT_MAX_EXPECT_CLASSES        4
  61
  62/* nf_conn feature for connections that have a helper */
  63struct nf_conn_help {
  64        /* Helper. if any */
  65        struct nf_conntrack_helper __rcu *helper;
  66
  67        struct hlist_head expectations;
  68
  69        /* Current number of expected connections */
  70        u8 expecting[NF_CT_MAX_EXPECT_CLASSES];
  71
  72        /* private helper information. */
  73        char data[32] __aligned(8);
  74};
  75
  76#define NF_CT_HELPER_BUILD_BUG_ON(structsize) \
  77        BUILD_BUG_ON((structsize) > FIELD_SIZEOF(struct nf_conn_help, data))
  78
  79struct nf_conntrack_helper *__nf_conntrack_helper_find(const char *name,
  80                                                       u16 l3num, u8 protonum);
  81
  82struct nf_conntrack_helper *nf_conntrack_helper_try_module_get(const char *name,
  83                                                               u16 l3num,
  84                                                               u8 protonum);
  85void nf_conntrack_helper_put(struct nf_conntrack_helper *helper);
  86
  87void nf_ct_helper_init(struct nf_conntrack_helper *helper,
  88                       u16 l3num, u16 protonum, const char *name,
  89                       u16 default_port, u16 spec_port, u32 id,
  90                       const struct nf_conntrack_expect_policy *exp_pol,
  91                       u32 expect_class_max,
  92                       int (*help)(struct sk_buff *skb, unsigned int protoff,
  93                                   struct nf_conn *ct,
  94                                   enum ip_conntrack_info ctinfo),
  95                       int (*from_nlattr)(struct nlattr *attr,
  96                                          struct nf_conn *ct),
  97                       struct module *module);
  98
  99int nf_conntrack_helper_register(struct nf_conntrack_helper *);
 100void nf_conntrack_helper_unregister(struct nf_conntrack_helper *);
 101
 102int nf_conntrack_helpers_register(struct nf_conntrack_helper *, unsigned int);
 103void nf_conntrack_helpers_unregister(struct nf_conntrack_helper *,
 104                                     unsigned int);
 105
 106struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp);
 107
 108int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
 109                              gfp_t flags);
 110
 111void nf_ct_helper_destroy(struct nf_conn *ct);
 112
 113static inline struct nf_conn_help *nfct_help(const struct nf_conn *ct)
 114{
 115        return nf_ct_ext_find(ct, NF_CT_EXT_HELPER);
 116}
 117
 118static inline void *nfct_help_data(const struct nf_conn *ct)
 119{
 120        struct nf_conn_help *help;
 121
 122        help = nf_ct_ext_find(ct, NF_CT_EXT_HELPER);
 123
 124        return (void *)help->data;
 125}
 126
 127void nf_conntrack_helper_pernet_init(struct net *net);
 128
 129int nf_conntrack_helper_init(void);
 130void nf_conntrack_helper_fini(void);
 131
 132int nf_conntrack_broadcast_help(struct sk_buff *skb, struct nf_conn *ct,
 133                                enum ip_conntrack_info ctinfo,
 134                                unsigned int timeout);
 135
 136struct nf_ct_helper_expectfn {
 137        struct list_head head;
 138        const char *name;
 139        void (*expectfn)(struct nf_conn *ct, struct nf_conntrack_expect *exp);
 140};
 141
 142__printf(3,4)
 143void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct,
 144                      const char *fmt, ...);
 145
 146void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n);
 147void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n);
 148struct nf_ct_helper_expectfn *
 149nf_ct_helper_expectfn_find_by_name(const char *name);
 150struct nf_ct_helper_expectfn *
 151nf_ct_helper_expectfn_find_by_symbol(const void *symbol);
 152
 153extern struct hlist_head *nf_ct_helper_hash;
 154extern unsigned int nf_ct_helper_hsize;
 155
 156#endif /*_NF_CONNTRACK_HELPER_H*/
 157