include/net/netfilter/nf_conntrack_helper.h

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