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 	/* length of internal data, ie. sizeof(struct nf_ct_*_master) */
33 	size_t data_len;
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 	unsigned int queue_num;		/* For user-space helpers. */
53 };
54 
55 extern struct nf_conntrack_helper *
56 __nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum);
57 
58 extern struct nf_conntrack_helper *
59 nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum);
60 
61 extern int nf_conntrack_helper_register(struct nf_conntrack_helper *);
62 extern void nf_conntrack_helper_unregister(struct nf_conntrack_helper *);
63 
64 extern struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, struct nf_conntrack_helper *helper, gfp_t gfp);
65 
66 extern int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
67 				     gfp_t flags);
68 
69 extern void nf_ct_helper_destroy(struct nf_conn *ct);
70 
71 static inline struct nf_conn_help *nfct_help(const struct nf_conn *ct)
72 {
73 	return nf_ct_ext_find(ct, NF_CT_EXT_HELPER);
74 }
75 
76 static inline void *nfct_help_data(const struct nf_conn *ct)
77 {
78 	struct nf_conn_help *help;
79 
80 	help = nf_ct_ext_find(ct, NF_CT_EXT_HELPER);
81 
82 	return (void *)help->data;
83 }
84 
85 extern int nf_conntrack_helper_init(struct net *net);
86 extern void nf_conntrack_helper_fini(struct net *net);
87 
88 extern int nf_conntrack_broadcast_help(struct sk_buff *skb,
89 				       unsigned int protoff,
90 				       struct nf_conn *ct,
91 				       enum ip_conntrack_info ctinfo,
92 				       unsigned int timeout);
93 
94 struct nf_ct_helper_expectfn {
95 	struct list_head head;
96 	const char *name;
97 	void (*expectfn)(struct nf_conn *ct, struct nf_conntrack_expect *exp);
98 };
99 
100 void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n);
101 void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n);
102 struct nf_ct_helper_expectfn *
103 nf_ct_helper_expectfn_find_by_name(const char *name);
104 struct nf_ct_helper_expectfn *
105 nf_ct_helper_expectfn_find_by_symbol(const void *symbol);
106 
107 extern struct hlist_head *nf_ct_helper_hash;
108 extern unsigned int nf_ct_helper_hsize;
109 
110 #endif /*_NF_CONNTRACK_HELPER_H*/
111