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1#ifndef __LINUX_NETFILTER_H
2#define __LINUX_NETFILTER_H
3
4#ifdef __KERNEL__
5#include <linux/init.h>
6#include <linux/skbuff.h>
7#include <linux/net.h>
8#include <linux/if.h>
9#include <linux/in.h>
10#include <linux/in6.h>
11#include <linux/wait.h>
12#include <linux/list.h>
13#endif
14#include <linux/types.h>
15#include <linux/compiler.h>
16#include <linux/sysctl.h>
17
18/* Responses from hook functions. */
19#define NF_DROP 0
20#define NF_ACCEPT 1
21#define NF_STOLEN 2
22#define NF_QUEUE 3
23#define NF_REPEAT 4
24#define NF_STOP 5
25#define NF_MAX_VERDICT NF_STOP
26
27/* we overload the higher bits for encoding auxiliary data such as the queue
28 * number or errno values. Not nice, but better than additional function
29 * arguments. */
30#define NF_VERDICT_MASK 0x000000ff
31
32/* extra verdict flags have mask 0x0000ff00 */
33#define NF_VERDICT_FLAG_QUEUE_BYPASS 0x00008000
34
35/* queue number (NF_QUEUE) or errno (NF_DROP) */
36#define NF_VERDICT_QMASK 0xffff0000
37#define NF_VERDICT_QBITS 16
38
39#define NF_QUEUE_NR(x) ((((x) << 16) & NF_VERDICT_QMASK) | NF_QUEUE)
40
41#define NF_DROP_ERR(x) (((-x) << 16) | NF_DROP)
42
43/* only for userspace compatibility */
44#ifndef __KERNEL__
45/* Generic cache responses from hook functions.
46 <= 0x2000 is used for protocol-flags. */
47#define NFC_UNKNOWN 0x4000
48#define NFC_ALTERED 0x8000
49
50/* NF_VERDICT_BITS should be 8 now, but userspace might break if this changes */
51#define NF_VERDICT_BITS 16
52#endif
53
54enum nf_inet_hooks {
55 NF_INET_PRE_ROUTING,
56 NF_INET_LOCAL_IN,
57 NF_INET_FORWARD,
58 NF_INET_LOCAL_OUT,
59 NF_INET_POST_ROUTING,
60 NF_INET_NUMHOOKS
61};
62
63enum {
64 NFPROTO_UNSPEC = 0,
65 NFPROTO_IPV4 = 2,
66 NFPROTO_ARP = 3,
67 NFPROTO_BRIDGE = 7,
68 NFPROTO_IPV6 = 10,
69 NFPROTO_DECNET = 12,
70 NFPROTO_NUMPROTO,
71};
72
73union nf_inet_addr {
74 __u32 all[4];
75 __be32 ip;
76 __be32 ip6[4];
77 struct in_addr in;
78 struct in6_addr in6;
79};
80
81#ifdef __KERNEL__
82#ifdef CONFIG_NETFILTER
83static inline int NF_DROP_GETERR(int verdict)
84{
85 return -(verdict >> NF_VERDICT_QBITS);
86}
87
88static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
89 const union nf_inet_addr *a2)
90{
91 return a1->all[0] == a2->all[0] &&
92 a1->all[1] == a2->all[1] &&
93 a1->all[2] == a2->all[2] &&
94 a1->all[3] == a2->all[3];
95}
96
97extern void netfilter_init(void);
98
99/* Largest hook number + 1 */
100#define NF_MAX_HOOKS 8
101
102struct sk_buff;
103
104typedef unsigned int nf_hookfn(unsigned int hooknum,
105 struct sk_buff *skb,
106 const struct net_device *in,
107 const struct net_device *out,
108 int (*okfn)(struct sk_buff *));
109
110struct nf_hook_ops {
111 struct list_head list;
112
113 /* User fills in from here down. */
114 nf_hookfn *hook;
115 struct module *owner;
116 u_int8_t pf;
117 unsigned int hooknum;
118 /* Hooks are ordered in ascending priority. */
119 int priority;
120};
121
122struct nf_sockopt_ops {
123 struct list_head list;
124
125 u_int8_t pf;
126
127 /* Non-inclusive ranges: use 0/0/NULL to never get called. */
128 int set_optmin;
129 int set_optmax;
130 int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
131#ifdef CONFIG_COMPAT
132 int (*compat_set)(struct sock *sk, int optval,
133 void __user *user, unsigned int len);
134#endif
135 int get_optmin;
136 int get_optmax;
137 int (*get)(struct sock *sk, int optval, void __user *user, int *len);
138#ifdef CONFIG_COMPAT
139 int (*compat_get)(struct sock *sk, int optval,
140 void __user *user, int *len);
141#endif
142 /* Use the module struct to lock set/get code in place */
143 struct module *owner;
144};
145
146/* Function to register/unregister hook points. */
147int nf_register_hook(struct nf_hook_ops *reg);
148void nf_unregister_hook(struct nf_hook_ops *reg);
149int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
150void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
151
152/* Functions to register get/setsockopt ranges (non-inclusive). You
153 need to check permissions yourself! */
154int nf_register_sockopt(struct nf_sockopt_ops *reg);
155void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
156
157extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
158
159#if defined(CONFIG_JUMP_LABEL)
160#include <linux/static_key.h>
161extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
162static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
163{
164 if (__builtin_constant_p(pf) &&
165 __builtin_constant_p(hook))
166 return static_key_false(&nf_hooks_needed[pf][hook]);
167
168 return !list_empty(&nf_hooks[pf][hook]);
169}
170#else
171static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
172{
173 return !list_empty(&nf_hooks[pf][hook]);
174}
175#endif
176
177int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
178 struct net_device *indev, struct net_device *outdev,
179 int (*okfn)(struct sk_buff *), int thresh);
180
181/**
182 * nf_hook_thresh - call a netfilter hook
183 *
184 * Returns 1 if the hook has allowed the packet to pass. The function
185 * okfn must be invoked by the caller in this case. Any other return
186 * value indicates the packet has been consumed by the hook.
187 */
188static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
189 struct sk_buff *skb,
190 struct net_device *indev,
191 struct net_device *outdev,
192 int (*okfn)(struct sk_buff *), int thresh)
193{
194 if (nf_hooks_active(pf, hook))
195 return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
196 return 1;
197}
198
199static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
200 struct net_device *indev, struct net_device *outdev,
201 int (*okfn)(struct sk_buff *))
202{
203 return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN);
204}
205
206/* Activate hook; either okfn or kfree_skb called, unless a hook
207 returns NF_STOLEN (in which case, it's up to the hook to deal with
208 the consequences).
209
210 Returns -ERRNO if packet dropped. Zero means queued, stolen or
211 accepted.
212*/
213
214/* RR:
215 > I don't want nf_hook to return anything because people might forget
216 > about async and trust the return value to mean "packet was ok".
217
218 AK:
219 Just document it clearly, then you can expect some sense from kernel
220 coders :)
221*/
222
223static inline int
224NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sk_buff *skb,
225 struct net_device *in, struct net_device *out,
226 int (*okfn)(struct sk_buff *), int thresh)
227{
228 int ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, thresh);
229 if (ret == 1)
230 ret = okfn(skb);
231 return ret;
232}
233
234static inline int
235NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb,
236 struct net_device *in, struct net_device *out,
237 int (*okfn)(struct sk_buff *), bool cond)
238{
239 int ret;
240
241 if (!cond ||
242 ((ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN)) == 1))
243 ret = okfn(skb);
244 return ret;
245}
246
247static inline int
248NF_HOOK(uint8_t pf, unsigned int hook, struct sk_buff *skb,
249 struct net_device *in, struct net_device *out,
250 int (*okfn)(struct sk_buff *))
251{
252 return NF_HOOK_THRESH(pf, hook, skb, in, out, okfn, INT_MIN);
253}
254
255/* Call setsockopt() */
256int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
257 unsigned int len);
258int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
259 int *len);
260#ifdef CONFIG_COMPAT
261int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
262 char __user *opt, unsigned int len);
263int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
264 char __user *opt, int *len);
265#endif
266
267/* Call this before modifying an existing packet: ensures it is
268 modifiable and linear to the point you care about (writable_len).
269 Returns true or false. */
270extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
271
272struct flowi;
273struct nf_queue_entry;
274
275struct nf_afinfo {
276 unsigned short family;
277 __sum16 (*checksum)(struct sk_buff *skb, unsigned int hook,
278 unsigned int dataoff, u_int8_t protocol);
279 __sum16 (*checksum_partial)(struct sk_buff *skb,
280 unsigned int hook,
281 unsigned int dataoff,
282 unsigned int len,
283 u_int8_t protocol);
284 int (*route)(struct net *net, struct dst_entry **dst,
285 struct flowi *fl, bool strict);
286 void (*saveroute)(const struct sk_buff *skb,
287 struct nf_queue_entry *entry);
288 int (*reroute)(struct sk_buff *skb,
289 const struct nf_queue_entry *entry);
290 int route_key_size;
291};
292
293extern const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO];
294static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
295{
296 return rcu_dereference(nf_afinfo[family]);
297}
298
299static inline __sum16
300nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
301 u_int8_t protocol, unsigned short family)
302{
303 const struct nf_afinfo *afinfo;
304 __sum16 csum = 0;
305
306 rcu_read_lock();
307 afinfo = nf_get_afinfo(family);
308 if (afinfo)
309 csum = afinfo->checksum(skb, hook, dataoff, protocol);
310 rcu_read_unlock();
311 return csum;
312}
313
314static inline __sum16
315nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
316 unsigned int dataoff, unsigned int len,
317 u_int8_t protocol, unsigned short family)
318{
319 const struct nf_afinfo *afinfo;
320 __sum16 csum = 0;
321
322 rcu_read_lock();
323 afinfo = nf_get_afinfo(family);
324 if (afinfo)
325 csum = afinfo->checksum_partial(skb, hook, dataoff, len,
326 protocol);
327 rcu_read_unlock();
328 return csum;
329}
330
331extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
332extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
333
334#include <net/flow.h>
335extern void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
336
337static inline void
338nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
339{
340#ifdef CONFIG_NF_NAT_NEEDED
341 void (*decodefn)(struct sk_buff *, struct flowi *);
342
343 if (family == AF_INET) {
344 rcu_read_lock();
345 decodefn = rcu_dereference(ip_nat_decode_session);
346 if (decodefn)
347 decodefn(skb, fl);
348 rcu_read_unlock();
349 }
350#endif
351}
352
353#ifdef CONFIG_PROC_FS
354#include <linux/proc_fs.h>
355extern struct proc_dir_entry *proc_net_netfilter;
356#endif
357
358#else /* !CONFIG_NETFILTER */
359#define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
360#define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
361static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
362 struct sk_buff *skb,
363 struct net_device *indev,
364 struct net_device *outdev,
365 int (*okfn)(struct sk_buff *), int thresh)
366{
367 return okfn(skb);
368}
369static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
370 struct net_device *indev, struct net_device *outdev,
371 int (*okfn)(struct sk_buff *))
372{
373 return 1;
374}
375struct flowi;
376static inline void
377nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
378{
379}
380#endif /*CONFIG_NETFILTER*/
381
382#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
383extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *) __rcu;
384extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
385extern void (*nf_ct_destroy)(struct nf_conntrack *) __rcu;
386#else
387static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
388#endif
389
390#endif /*__KERNEL__*/
391#endif /*__LINUX_NETFILTER_H*/