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 int nf_ct_helper(struct sk_buff *skb, struct nf_conn *ct,
119 enum ip_conntrack_info ctinfo, u16 proto);
120 int nf_ct_add_helper(struct nf_conn *ct, const char *name, u8 family,
121 u8 proto, bool nat, struct nf_conntrack_helper **hp);
122
123 void nf_ct_helper_destroy(struct nf_conn *ct);
124
nfct_help(const struct nf_conn * ct)125 static 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
nfct_help_data(const struct nf_conn * ct)130 static 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
139 int nf_conntrack_helper_init(void);
140 void nf_conntrack_helper_fini(void);
141
142 int nf_conntrack_broadcast_help(struct sk_buff *skb, struct nf_conn *ct,
143 enum ip_conntrack_info ctinfo,
144 unsigned int timeout);
145
146 struct 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)
153 void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct,
154 const char *fmt, ...);
155
156 void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n);
157 void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n);
158 struct nf_ct_helper_expectfn *
159 nf_ct_helper_expectfn_find_by_name(const char *name);
160 struct nf_ct_helper_expectfn *
161 nf_ct_helper_expectfn_find_by_symbol(const void *symbol);
162
163 extern struct hlist_head *nf_ct_helper_hash;
164 extern unsigned int nf_ct_helper_hsize;
165
166 struct 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
178 void nf_nat_helper_register(struct nf_conntrack_nat_helper *nat);
179 void nf_nat_helper_unregister(struct nf_conntrack_nat_helper *nat);
180 int nf_nat_helper_try_module_get(const char *name, u16 l3num,
181 u8 protonum);
182 void nf_nat_helper_put(struct nf_conntrack_helper *helper);
183 #endif /*_NF_CONNTRACK_HELPER_H*/
184