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 <linux/refcount.h>
  13 #include <net/netfilter/nf_conntrack.h>
  14 #include <net/netfilter/nf_conntrack_extend.h>
  15 #include <net/netfilter/nf_conntrack_expect.h>
  16
  17 struct module;
  18
  19 enum nf_ct_helper_flags {
  20         NF_CT_HELPER_F_USERSPACE        = (1 << 0),
  21         NF_CT_HELPER_F_CONFIGURED       = (1 << 1),
  22 };
  23
  24 #define NF_CT_HELPER_NAME_LEN   16
  25
  26 struct nf_conntrack_helper {
  27         struct hlist_node hnode;        /* Internal use. */
  28
  29         char name[NF_CT_HELPER_NAME_LEN]; /* name of the module */
  30         refcount_t refcnt;
  31         struct module *me;              /* pointer to self */
  32         const struct nf_conntrack_expect_policy *expect_policy;
  33
  34         /* Tuple of things we will help (compared against server response) */
  35         struct nf_conntrack_tuple tuple;
  36
  37         /* Function to call when data passes; return verdict, or -1 to
  38            invalidate. */
  39         int (*help)(struct sk_buff *skb,
  40                     unsigned int protoff,
  41                     struct nf_conn *ct,
  42                     enum ip_conntrack_info conntrackinfo);
  43
  44         void (*destroy)(struct nf_conn *ct);
  45
  46         int (*from_nlattr)(struct nlattr *attr, struct nf_conn *ct);
  47         int (*to_nlattr)(struct sk_buff *skb, const struct nf_conn *ct);
  48         unsigned int expect_class_max;
  49
  50         unsigned int flags;
  51
  52         /* For user-space helpers: */
  53         unsigned int queue_num;
  54         /* length of userspace private data stored in nf_conn_help->data */
  55         u16 data_len;
  56 };
  57
  58 /* Must be kept in sync with the classes defined by helpers */
  59 #define NF_CT_MAX_EXPECT_CLASSES        4
  60
  61 /* nf_conn feature for connections that have a helper */
  62 struct nf_conn_help {
  63         /* Helper. if any */
  64         struct nf_conntrack_helper __rcu *helper;
  65
  66         struct hlist_head expectations;
  67
  68         /* Current number of expected connections */
  69         u8 expecting[NF_CT_MAX_EXPECT_CLASSES];
  70
  71         /* private helper information. */
  72         char data[32] __aligned(8);
  73 };
  74
  75 #define NF_CT_HELPER_BUILD_BUG_ON(structsize) \
  76         BUILD_BUG_ON((structsize) > FIELD_SIZEOF(struct nf_conn_help, data))
  77
  78 struct nf_conntrack_helper *__nf_conntrack_helper_find(const char *name,
  79                                                        u16 l3num, u8 protonum);
  80
  81 struct nf_conntrack_helper *nf_conntrack_helper_try_module_get(const char *name,
  82                                                                u16 l3num,
  83                                                                u8 protonum);
  84 void nf_conntrack_helper_put(struct nf_conntrack_helper *helper);
  85
  86 void nf_ct_helper_init(struct nf_conntrack_helper *helper,
  87                        u16 l3num, u16 protonum, const char *name,
  88                        u16 default_port, u16 spec_port, u32 id,
  89                        const struct nf_conntrack_expect_policy *exp_pol,
  90                        u32 expect_class_max,
  91                        int (*help)(struct sk_buff *skb, unsigned int protoff,
  92                                    struct nf_conn *ct,
  93                                    enum ip_conntrack_info ctinfo),
  94                        int (*from_nlattr)(struct nlattr *attr,
  95                                           struct nf_conn *ct),
  96                        struct module *module);
  97
  98 int nf_conntrack_helper_register(struct nf_conntrack_helper *);
  99 void nf_conntrack_helper_unregister(struct nf_conntrack_helper *);
 100
 101 int nf_conntrack_helpers_register(struct nf_conntrack_helper *, unsigned int);
 102 void nf_conntrack_helpers_unregister(struct nf_conntrack_helper *,
 103                                      unsigned int);
 104
 105 struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct,
 106                                           struct nf_conntrack_helper *helper,
 107                                           gfp_t gfp);
 108
 109 int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
 110                               gfp_t flags);
 111
 112 void nf_ct_helper_destroy(struct nf_conn *ct);
 113
 114 static inline struct nf_conn_help *nfct_help(const struct nf_conn *ct)
 115 {
 116         return nf_ct_ext_find(ct, NF_CT_EXT_HELPER);
 117 }
 118
 119 static inline void *nfct_help_data(const struct nf_conn *ct)
 120 {
 121         struct nf_conn_help *help;
 122
 123         help = nf_ct_ext_find(ct, NF_CT_EXT_HELPER);
 124
 125         return (void *)help->data;
 126 }
 127
 128 int nf_conntrack_helper_pernet_init(struct net *net);
 129 void nf_conntrack_helper_pernet_fini(struct net *net);
 130
 131 int nf_conntrack_helper_init(void);
 132 void nf_conntrack_helper_fini(void);
 133
 134 int nf_conntrack_broadcast_help(struct sk_buff *skb, unsigned int protoff,
 135                                 struct nf_conn *ct,
 136                                 enum ip_conntrack_info ctinfo,
 137                                 unsigned int timeout);
 138
 139 struct nf_ct_helper_expectfn {
 140         struct list_head head;
 141         const char *name;
 142         void (*expectfn)(struct nf_conn *ct, struct nf_conntrack_expect *exp);
 143 };
 144
 145 __printf(3,4)
 146 void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct,
 147                       const char *fmt, ...);
 148
 149 void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n);
 150 void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n);
 151 struct nf_ct_helper_expectfn *
 152 nf_ct_helper_expectfn_find_by_name(const char *name);
 153 struct nf_ct_helper_expectfn *
 154 nf_ct_helper_expectfn_find_by_symbol(const void *symbol);
 155
 156 extern struct hlist_head *nf_ct_helper_hash;
 157 extern unsigned int nf_ct_helper_hsize;
 158
 159 #endif /*_NF_CONNTRACK_HELPER_H*/