include/net/netfilter/nf_conntrack_helper.h

   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
  18 struct module;
  19
  20 enum 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
  27 struct 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 */
  63 struct 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
  79 struct nf_conntrack_helper *__nf_conntrack_helper_find(const char *name,
  80                                                        u16 l3num, u8 protonum);
  81
  82 struct nf_conntrack_helper *nf_conntrack_helper_try_module_get(const char *name,
  83                                                                u16 l3num,
  84                                                                u8 protonum);
  85 void nf_conntrack_helper_put(struct nf_conntrack_helper *helper);
  86
  87 void 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
  99 int nf_conntrack_helper_register(struct nf_conntrack_helper *);
 100 void nf_conntrack_helper_unregister(struct nf_conntrack_helper *);
 101
 102 int nf_conntrack_helpers_register(struct nf_conntrack_helper *, unsigned int);
 103 void nf_conntrack_helpers_unregister(struct nf_conntrack_helper *,
 104                                      unsigned int);
 105
 106 struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct,
 107                                           struct nf_conntrack_helper *helper,
 108                                           gfp_t gfp);
 109
 110 int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
 111                               gfp_t flags);
 112
 113 void nf_ct_helper_destroy(struct nf_conn *ct);
 114
 115 static inline struct nf_conn_help *nfct_help(const struct nf_conn *ct)
 116 {
 117         return nf_ct_ext_find(ct, NF_CT_EXT_HELPER);
 118 }
 119
 120 static inline void *nfct_help_data(const struct nf_conn *ct)
 121 {
 122         struct nf_conn_help *help;
 123
 124         help = nf_ct_ext_find(ct, NF_CT_EXT_HELPER);
 125
 126         return (void *)help->data;
 127 }
 128
 129 int nf_conntrack_helper_pernet_init(struct net *net);
 130 void nf_conntrack_helper_pernet_fini(struct net *net);
 131
 132 int nf_conntrack_helper_init(void);
 133 void nf_conntrack_helper_fini(void);
 134
 135 int nf_conntrack_broadcast_help(struct sk_buff *skb, unsigned int protoff,
 136                                 struct nf_conn *ct,
 137                                 enum ip_conntrack_info ctinfo,
 138                                 unsigned int timeout);
 139
 140 struct nf_ct_helper_expectfn {
 141         struct list_head head;
 142         const char *name;
 143         void (*expectfn)(struct nf_conn *ct, struct nf_conntrack_expect *exp);
 144 };
 145
 146 __printf(3,4)
 147 void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct,
 148                       const char *fmt, ...);
 149
 150 void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n);
 151 void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n);
 152 struct nf_ct_helper_expectfn *
 153 nf_ct_helper_expectfn_find_by_name(const char *name);
 154 struct nf_ct_helper_expectfn *
 155 nf_ct_helper_expectfn_find_by_symbol(const void *symbol);
 156
 157 extern struct hlist_head *nf_ct_helper_hash;
 158 extern unsigned int nf_ct_helper_hsize;
 159
 160 #endif /*_NF_CONNTRACK_HELPER_H*/