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 #define NF_NAT_HELPER_PREFIX            "ip_nat_"
  19 #define NF_NAT_HELPER_NAME(name)        NF_NAT_HELPER_PREFIX name
  20 #define MODULE_ALIAS_NF_NAT_HELPER(name) \
  21         MODULE_ALIAS(NF_NAT_HELPER_NAME(name))
  22
  23 struct module;
  24
  25 enum nf_ct_helper_flags {
  26         NF_CT_HELPER_F_USERSPACE        = (1 << 0),
  27         NF_CT_HELPER_F_CONFIGURED       = (1 << 1),
  28 };
  29
  30 #define NF_CT_HELPER_NAME_LEN   16
  31
  32 struct nf_conntrack_helper {
  33         struct hlist_node hnode;        /* Internal use. */
  34
  35         char name[NF_CT_HELPER_NAME_LEN]; /* name of the module */
  36         refcount_t refcnt;
  37         struct module *me;              /* pointer to self */
  38         const struct nf_conntrack_expect_policy *expect_policy;
  39
  40         /* Tuple of things we will help (compared against server response) */
  41         struct nf_conntrack_tuple tuple;
  42
  43         /* Function to call when data passes; return verdict, or -1 to
  44            invalidate. */
  45         int (*help)(struct sk_buff *skb,
  46                     unsigned int protoff,
  47                     struct nf_conn *ct,
  48                     enum ip_conntrack_info conntrackinfo);
  49
  50         void (*destroy)(struct nf_conn *ct);
  51
  52         int (*from_nlattr)(struct nlattr *attr, struct nf_conn *ct);
  53         int (*to_nlattr)(struct sk_buff *skb, const struct nf_conn *ct);
  54         unsigned int expect_class_max;
  55
  56         unsigned int flags;
  57
  58         /* For user-space helpers: */
  59         unsigned int queue_num;
  60         /* length of userspace private data stored in nf_conn_help->data */
  61         u16 data_len;
  62         /* name of NAT helper module */
  63         char nat_mod_name[NF_CT_HELPER_NAME_LEN];
  64 };
  65
  66 /* Must be kept in sync with the classes defined by helpers */
  67 #define NF_CT_MAX_EXPECT_CLASSES        4
  68
  69 /* nf_conn feature for connections that have a helper */
  70 struct nf_conn_help {
  71         /* Helper. if any */
  72         struct nf_conntrack_helper __rcu *helper;
  73
  74         struct hlist_head expectations;
  75
  76         /* Current number of expected connections */
  77         u8 expecting[NF_CT_MAX_EXPECT_CLASSES];
  78
  79         /* private helper information. */
  80         char data[32] __aligned(8);
  81 };
  82
  83 #define NF_CT_HELPER_BUILD_BUG_ON(structsize) \
  84         BUILD_BUG_ON((structsize) > sizeof_field(struct nf_conn_help, data))
  85
  86 struct nf_conntrack_helper *__nf_conntrack_helper_find(const char *name,
  87                                                        u16 l3num, u8 protonum);
  88
  89 struct nf_conntrack_helper *nf_conntrack_helper_try_module_get(const char *name,
  90                                                                u16 l3num,
  91                                                                u8 protonum);
  92 void nf_conntrack_helper_put(struct nf_conntrack_helper *helper);
  93
  94 void nf_ct_helper_init(struct nf_conntrack_helper *helper,
  95                        u16 l3num, u16 protonum, const char *name,
  96                        u16 default_port, u16 spec_port, u32 id,
  97                        const struct nf_conntrack_expect_policy *exp_pol,
  98                        u32 expect_class_max,
  99                        int (*help)(struct sk_buff *skb, unsigned int protoff,
 100                                    struct nf_conn *ct,
 101                                    enum ip_conntrack_info ctinfo),
 102                        int (*from_nlattr)(struct nlattr *attr,
 103                                           struct nf_conn *ct),
 104                        struct module *module);
 105
 106 int nf_conntrack_helper_register(struct nf_conntrack_helper *);
 107 void nf_conntrack_helper_unregister(struct nf_conntrack_helper *);
 108
 109 int nf_conntrack_helpers_register(struct nf_conntrack_helper *, unsigned int);
 110 void nf_conntrack_helpers_unregister(struct nf_conntrack_helper *,
 111                                      unsigned int);
 112
 113 struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp);
 114
 115 int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
 116                               gfp_t flags);
 117
 118 void nf_ct_helper_destroy(struct nf_conn *ct);
 119
 120 static inline struct nf_conn_help *nfct_help(const struct nf_conn *ct)
 121 {
 122         return nf_ct_ext_find(ct, NF_CT_EXT_HELPER);
 123 }
 124
 125 static inline void *nfct_help_data(const struct nf_conn *ct)
 126 {
 127         struct nf_conn_help *help;
 128
 129         help = nf_ct_ext_find(ct, NF_CT_EXT_HELPER);
 130
 131         return (void *)help->data;
 132 }
 133
 134 void nf_conntrack_helper_pernet_init(struct net *net);
 135
 136 int nf_conntrack_helper_init(void);
 137 void nf_conntrack_helper_fini(void);
 138
 139 int nf_conntrack_broadcast_help(struct sk_buff *skb, struct nf_conn *ct,
 140                                 enum ip_conntrack_info ctinfo,
 141                                 unsigned int timeout);
 142
 143 struct nf_ct_helper_expectfn {
 144         struct list_head head;
 145         const char *name;
 146         void (*expectfn)(struct nf_conn *ct, struct nf_conntrack_expect *exp);
 147 };
 148
 149 __printf(3,4)
 150 void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct,
 151                       const char *fmt, ...);
 152
 153 void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n);
 154 void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n);
 155 struct nf_ct_helper_expectfn *
 156 nf_ct_helper_expectfn_find_by_name(const char *name);
 157 struct nf_ct_helper_expectfn *
 158 nf_ct_helper_expectfn_find_by_symbol(const void *symbol);
 159
 160 extern struct hlist_head *nf_ct_helper_hash;
 161 extern unsigned int nf_ct_helper_hsize;
 162
 163 struct nf_conntrack_nat_helper {
 164         struct list_head list;
 165         char mod_name[NF_CT_HELPER_NAME_LEN];   /* module name */
 166         struct module *module;                  /* pointer to self */
 167 };
 168
 169 #define NF_CT_NAT_HELPER_INIT(name) \
 170         { \
 171         .mod_name = NF_NAT_HELPER_NAME(name), \
 172         .module = THIS_MODULE \
 173         }
 174
 175 void nf_nat_helper_register(struct nf_conntrack_nat_helper *nat);
 176 void nf_nat_helper_unregister(struct nf_conntrack_nat_helper *nat);
 177 int nf_nat_helper_try_module_get(const char *name, u16 l3num,
 178                                  u8 protonum);
 179 void nf_nat_helper_put(struct nf_conntrack_helper *helper);
 180 #endif /*_NF_CONNTRACK_HELPER_H*/