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