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
 23struct module;
 24
 25enum 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
 32struct 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 */
 70struct 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
 86struct nf_conntrack_helper *__nf_conntrack_helper_find(const char *name,
 87						       u16 l3num, u8 protonum);
 88
 89struct nf_conntrack_helper *nf_conntrack_helper_try_module_get(const char *name,
 90							       u16 l3num,
 91							       u8 protonum);
 92void nf_conntrack_helper_put(struct nf_conntrack_helper *helper);
 93
 94void 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
106int nf_conntrack_helper_register(struct nf_conntrack_helper *);
107void nf_conntrack_helper_unregister(struct nf_conntrack_helper *);
108
109int nf_conntrack_helpers_register(struct nf_conntrack_helper *, unsigned int);
110void nf_conntrack_helpers_unregister(struct nf_conntrack_helper *,
111				     unsigned int);
112
113struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp);
114
115int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
116			      gfp_t flags);
117
118int nf_ct_helper(struct sk_buff *skb, struct nf_conn *ct,
119		 enum ip_conntrack_info ctinfo, u16 proto);
120int nf_ct_add_helper(struct nf_conn *ct, const char *name, u8 family,
121		     u8 proto, bool nat, struct nf_conntrack_helper **hp);
122
123void nf_ct_helper_destroy(struct nf_conn *ct);
124
125static inline struct nf_conn_help *nfct_help(const struct nf_conn *ct)
126{
127	return nf_ct_ext_find(ct, NF_CT_EXT_HELPER);
128}
129
130static inline void *nfct_help_data(const struct nf_conn *ct)
131{
132	struct nf_conn_help *help;
133
134	help = nf_ct_ext_find(ct, NF_CT_EXT_HELPER);
135
136	return (void *)help->data;
137}
138
139int nf_conntrack_helper_init(void);
140void nf_conntrack_helper_fini(void);
141
142int nf_conntrack_broadcast_help(struct sk_buff *skb, struct nf_conn *ct,
143				enum ip_conntrack_info ctinfo,
144				unsigned int timeout);
145
146struct nf_ct_helper_expectfn {
147	struct list_head head;
148	const char *name;
149	void (*expectfn)(struct nf_conn *ct, struct nf_conntrack_expect *exp);
150};
151
152__printf(3,4)
153void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct,
154		      const char *fmt, ...);
155
156void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n);
157void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n);
158struct nf_ct_helper_expectfn *
159nf_ct_helper_expectfn_find_by_name(const char *name);
160struct nf_ct_helper_expectfn *
161nf_ct_helper_expectfn_find_by_symbol(const void *symbol);
162
163extern struct hlist_head *nf_ct_helper_hash;
164extern unsigned int nf_ct_helper_hsize;
165
166struct nf_conntrack_nat_helper {
167	struct list_head list;
168	char mod_name[NF_CT_HELPER_NAME_LEN];	/* module name */
169	struct module *module;			/* pointer to self */
170};
171
172#define NF_CT_NAT_HELPER_INIT(name) \
173	{ \
174	.mod_name = NF_NAT_HELPER_NAME(name), \
175	.module = THIS_MODULE \
176	}
177
178void nf_nat_helper_register(struct nf_conntrack_nat_helper *nat);
179void nf_nat_helper_unregister(struct nf_conntrack_nat_helper *nat);
180int nf_nat_helper_try_module_get(const char *name, u16 l3num,
181				 u8 protonum);
182void nf_nat_helper_put(struct nf_conntrack_helper *helper);
183#endif /*_NF_CONNTRACK_HELPER_H*/