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 /* Must be kept in sync with the classes defined by helpers */
33 #define NF_CT_MAX_EXPECT_CLASSES 4
34
35 struct nf_conntrack_helper {
36 struct hlist_node hnode; /* Internal use. */
37
38 struct rcu_head rcu;
39
40 char name[NF_CT_HELPER_NAME_LEN]; /* name of the module */
41 struct module *me; /* pointer to self */
42 struct nf_conntrack_expect_policy expect_policy[NF_CT_MAX_EXPECT_CLASSES];
43
44 refcount_t ct_refcnt;
45
46 u8 nfproto; /* NFPROTO_*, can be NFPROTO_UNSPEC */
47 u8 l4proto; /* IPPROTO_UDP/TCP */
48
49 /* Function to call when data passes; return verdict */
50 int __rcu (*help)(struct sk_buff *skb, unsigned int protoff,
51 struct nf_conn *ct,
52 enum ip_conntrack_info conntrackinfo);
53
54 void (*destroy)(struct nf_conn *ct);
55
56 int (*from_nlattr)(struct nlattr *attr, struct nf_conn *ct);
57 int (*to_nlattr)(struct sk_buff *skb, const struct nf_conn *ct);
58 unsigned int expect_class_max;
59
60 unsigned int flags;
61
62 /* For user-space helpers: */
63 unsigned int queue_num;
64 /* length of userspace private data stored in nf_conn_help->data */
65 u16 data_len;
66 /* name of NAT helper module */
67 char nat_mod_name[NF_CT_HELPER_NAME_LEN];
68 };
69
70 /* nf_conn feature for connections that have a helper */
71 struct nf_conn_help {
72 /* Helper. if any */
73 struct nf_conntrack_helper __rcu *helper;
74
75 struct hlist_head expectations;
76
77 /* Current number of expected connections */
78 u8 expecting[NF_CT_MAX_EXPECT_CLASSES];
79
80 /* private helper information. */
81 char data[32] __aligned(8);
82 };
83
84 #define NF_CT_HELPER_BUILD_BUG_ON(structsize) \
85 BUILD_BUG_ON((structsize) > sizeof_field(struct nf_conn_help, data))
86
87 struct nf_conntrack_helper *__nf_conntrack_helper_find(const char *name,
88 u16 l3num, u8 protonum);
89
90 struct nf_conntrack_helper *nf_conntrack_helper_try_module_get(const char *name,
91 u16 l3num,
92 u8 protonum);
93 void nf_conntrack_helper_put(struct nf_conntrack_helper *helper);
94
95 void nf_ct_helper_init(struct nf_conntrack_helper *helper,
96 u8 l3num, u16 protonum, const char *name,
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 *, struct nf_conntrack_helper **);
107 int __nf_conntrack_helper_register(struct nf_conntrack_helper *);
108 void nf_conntrack_helper_unregister(struct nf_conntrack_helper *);
109 void nf_conntrack_helper_release(struct nf_conntrack_helper *);
110
111 int nf_conntrack_helpers_register(struct nf_conntrack_helper *, unsigned int,
112 struct nf_conntrack_helper **);
113 void nf_conntrack_helpers_unregister(struct nf_conntrack_helper **,
114 unsigned int);
115
116 #define nf_conntrack_helper_deprecated(name) \
117 pr_warn("The %s conntrack helper is scheduled for removal.\n" \
118 "Please contact the netfilter-devel mailing list if you still need this.\n", name)
119
120 struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp);
121
122 int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
123 gfp_t flags);
124
125 int nf_ct_helper(struct sk_buff *skb, struct nf_conn *ct,
126 enum ip_conntrack_info ctinfo, u16 proto);
127 int nf_ct_add_helper(struct nf_conn *ct, const char *name, u8 family,
128 u8 proto, bool nat, struct nf_conntrack_helper **hp);
129
130 void nf_ct_helper_destroy(struct nf_conn *ct);
131
nfct_help(const struct nf_conn * ct)132 static inline struct nf_conn_help *nfct_help(const struct nf_conn *ct)
133 {
134 return nf_ct_ext_find(ct, NF_CT_EXT_HELPER);
135 }
136
nfct_help_data(const struct nf_conn * ct)137 static inline void *nfct_help_data(const struct nf_conn *ct)
138 {
139 struct nf_conn_help *help;
140
141 help = nf_ct_ext_find(ct, NF_CT_EXT_HELPER);
142 if (!help)
143 return NULL;
144
145 return (void *)help->data;
146 }
147
nf_ct_help_put(const struct nf_conn * ct)148 static inline void nf_ct_help_put(const struct nf_conn *ct)
149 {
150 struct nf_conntrack_helper *helper;
151 struct nf_conn_help *help;
152
153 help = nfct_help(ct);
154 if (!help)
155 return;
156
157 helper = rcu_dereference(help->helper);
158 if (helper && refcount_dec_and_test(&helper->ct_refcnt))
159 kfree_rcu(helper, rcu);
160 }
161
162 int nf_conntrack_helper_init(void);
163 void nf_conntrack_helper_fini(void);
164
165 int nf_conntrack_broadcast_help(struct sk_buff *skb, struct nf_conn *ct,
166 enum ip_conntrack_info ctinfo,
167 unsigned int timeout);
168
169 struct nf_ct_helper_expectfn {
170 struct list_head head;
171 const char *name;
172 void (*expectfn)(struct nf_conn *ct, struct nf_conntrack_expect *exp);
173 };
174
175 __printf(3,4)
176 void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct,
177 const char *fmt, ...);
178
179 void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n);
180 void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n);
181 void nf_ct_helper_expectfn_destroy(const struct nf_ct_helper_expectfn *n);
182 struct nf_ct_helper_expectfn *
183 nf_ct_helper_expectfn_find_by_name(const char *name);
184 struct nf_ct_helper_expectfn *
185 nf_ct_helper_expectfn_find_by_symbol(const void *symbol);
186
187 extern struct hlist_head *nf_ct_helper_hash;
188 extern unsigned int nf_ct_helper_hsize;
189
190 struct nf_conntrack_nat_helper {
191 struct list_head list;
192 char mod_name[NF_CT_HELPER_NAME_LEN]; /* module name */
193 struct module *module; /* pointer to self */
194 };
195
196 #define NF_CT_NAT_HELPER_INIT(name) \
197 { \
198 .mod_name = NF_NAT_HELPER_NAME(name), \
199 .module = THIS_MODULE \
200 }
201
202 void nf_nat_helper_register(struct nf_conntrack_nat_helper *nat);
203 void nf_nat_helper_unregister(struct nf_conntrack_nat_helper *nat);
204 int nf_nat_helper_try_module_get(const char *name, u16 l3num,
205 u8 protonum);
206 void nf_nat_helper_put(struct nf_conntrack_helper *helper);
207 #endif /*_NF_CONNTRACK_HELPER_H*/
208