xref: /openbmc/linux/include/linux/netfilter.h (revision 9fb29c73)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __LINUX_NETFILTER_H
3 #define __LINUX_NETFILTER_H
4 
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 #include <linux/static_key.h>
14 #include <linux/netfilter_defs.h>
15 #include <linux/netdevice.h>
16 #include <net/net_namespace.h>
17 
18 #ifdef CONFIG_NETFILTER
19 static inline int NF_DROP_GETERR(int verdict)
20 {
21 	return -(verdict >> NF_VERDICT_QBITS);
22 }
23 
24 static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
25 				   const union nf_inet_addr *a2)
26 {
27 	return a1->all[0] == a2->all[0] &&
28 	       a1->all[1] == a2->all[1] &&
29 	       a1->all[2] == a2->all[2] &&
30 	       a1->all[3] == a2->all[3];
31 }
32 
33 static inline void nf_inet_addr_mask(const union nf_inet_addr *a1,
34 				     union nf_inet_addr *result,
35 				     const union nf_inet_addr *mask)
36 {
37 	result->all[0] = a1->all[0] & mask->all[0];
38 	result->all[1] = a1->all[1] & mask->all[1];
39 	result->all[2] = a1->all[2] & mask->all[2];
40 	result->all[3] = a1->all[3] & mask->all[3];
41 }
42 
43 int netfilter_init(void);
44 
45 struct sk_buff;
46 
47 struct nf_hook_ops;
48 
49 struct sock;
50 
51 struct nf_hook_state {
52 	unsigned int hook;
53 	u_int8_t pf;
54 	struct net_device *in;
55 	struct net_device *out;
56 	struct sock *sk;
57 	struct net *net;
58 	int (*okfn)(struct net *, struct sock *, struct sk_buff *);
59 };
60 
61 typedef unsigned int nf_hookfn(void *priv,
62 			       struct sk_buff *skb,
63 			       const struct nf_hook_state *state);
64 struct nf_hook_ops {
65 	/* User fills in from here down. */
66 	nf_hookfn		*hook;
67 	struct net_device	*dev;
68 	void			*priv;
69 	u_int8_t		pf;
70 	unsigned int		hooknum;
71 	/* Hooks are ordered in ascending priority. */
72 	int			priority;
73 };
74 
75 struct nf_hook_entry {
76 	nf_hookfn			*hook;
77 	void				*priv;
78 };
79 
80 struct nf_hook_entries_rcu_head {
81 	struct rcu_head head;
82 	void	*allocation;
83 };
84 
85 struct nf_hook_entries {
86 	u16				num_hook_entries;
87 	/* padding */
88 	struct nf_hook_entry		hooks[];
89 
90 	/* trailer: pointers to original orig_ops of each hook,
91 	 * followed by rcu_head and scratch space used for freeing
92 	 * the structure via call_rcu.
93 	 *
94 	 *   This is not part of struct nf_hook_entry since its only
95 	 *   needed in slow path (hook register/unregister):
96 	 * const struct nf_hook_ops     *orig_ops[]
97 	 *
98 	 *   For the same reason, we store this at end -- its
99 	 *   only needed when a hook is deleted, not during
100 	 *   packet path processing:
101 	 * struct nf_hook_entries_rcu_head     head
102 	 */
103 };
104 
105 static inline struct nf_hook_ops **nf_hook_entries_get_hook_ops(const struct nf_hook_entries *e)
106 {
107 	unsigned int n = e->num_hook_entries;
108 	const void *hook_end;
109 
110 	hook_end = &e->hooks[n]; /* this is *past* ->hooks[]! */
111 
112 	return (struct nf_hook_ops **)hook_end;
113 }
114 
115 static inline int
116 nf_hook_entry_hookfn(const struct nf_hook_entry *entry, struct sk_buff *skb,
117 		     struct nf_hook_state *state)
118 {
119 	return entry->hook(entry->priv, skb, state);
120 }
121 
122 static inline void nf_hook_state_init(struct nf_hook_state *p,
123 				      unsigned int hook,
124 				      u_int8_t pf,
125 				      struct net_device *indev,
126 				      struct net_device *outdev,
127 				      struct sock *sk,
128 				      struct net *net,
129 				      int (*okfn)(struct net *, struct sock *, struct sk_buff *))
130 {
131 	p->hook = hook;
132 	p->pf = pf;
133 	p->in = indev;
134 	p->out = outdev;
135 	p->sk = sk;
136 	p->net = net;
137 	p->okfn = okfn;
138 }
139 
140 
141 
142 struct nf_sockopt_ops {
143 	struct list_head list;
144 
145 	u_int8_t pf;
146 
147 	/* Non-inclusive ranges: use 0/0/NULL to never get called. */
148 	int set_optmin;
149 	int set_optmax;
150 	int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
151 #ifdef CONFIG_COMPAT
152 	int (*compat_set)(struct sock *sk, int optval,
153 			void __user *user, unsigned int len);
154 #endif
155 	int get_optmin;
156 	int get_optmax;
157 	int (*get)(struct sock *sk, int optval, void __user *user, int *len);
158 #ifdef CONFIG_COMPAT
159 	int (*compat_get)(struct sock *sk, int optval,
160 			void __user *user, int *len);
161 #endif
162 	/* Use the module struct to lock set/get code in place */
163 	struct module *owner;
164 };
165 
166 /* Function to register/unregister hook points. */
167 int nf_register_net_hook(struct net *net, const struct nf_hook_ops *ops);
168 void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *ops);
169 int nf_register_net_hooks(struct net *net, const struct nf_hook_ops *reg,
170 			  unsigned int n);
171 void nf_unregister_net_hooks(struct net *net, const struct nf_hook_ops *reg,
172 			     unsigned int n);
173 
174 /* Functions to register get/setsockopt ranges (non-inclusive).  You
175    need to check permissions yourself! */
176 int nf_register_sockopt(struct nf_sockopt_ops *reg);
177 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
178 
179 #ifdef CONFIG_JUMP_LABEL
180 extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
181 #endif
182 
183 int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state,
184 		 const struct nf_hook_entries *e, unsigned int i);
185 
186 /**
187  *	nf_hook - call a netfilter hook
188  *
189  *	Returns 1 if the hook has allowed the packet to pass.  The function
190  *	okfn must be invoked by the caller in this case.  Any other return
191  *	value indicates the packet has been consumed by the hook.
192  */
193 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,
194 			  struct sock *sk, struct sk_buff *skb,
195 			  struct net_device *indev, struct net_device *outdev,
196 			  int (*okfn)(struct net *, struct sock *, struct sk_buff *))
197 {
198 	struct nf_hook_entries *hook_head = NULL;
199 	int ret = 1;
200 
201 #ifdef CONFIG_JUMP_LABEL
202 	if (__builtin_constant_p(pf) &&
203 	    __builtin_constant_p(hook) &&
204 	    !static_key_false(&nf_hooks_needed[pf][hook]))
205 		return 1;
206 #endif
207 
208 	rcu_read_lock();
209 	switch (pf) {
210 	case NFPROTO_IPV4:
211 		hook_head = rcu_dereference(net->nf.hooks_ipv4[hook]);
212 		break;
213 	case NFPROTO_IPV6:
214 		hook_head = rcu_dereference(net->nf.hooks_ipv6[hook]);
215 		break;
216 	case NFPROTO_ARP:
217 #ifdef CONFIG_NETFILTER_FAMILY_ARP
218 		if (WARN_ON_ONCE(hook >= ARRAY_SIZE(net->nf.hooks_arp)))
219 			break;
220 		hook_head = rcu_dereference(net->nf.hooks_arp[hook]);
221 #endif
222 		break;
223 	case NFPROTO_BRIDGE:
224 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
225 		hook_head = rcu_dereference(net->nf.hooks_bridge[hook]);
226 #endif
227 		break;
228 #if IS_ENABLED(CONFIG_DECNET)
229 	case NFPROTO_DECNET:
230 		hook_head = rcu_dereference(net->nf.hooks_decnet[hook]);
231 		break;
232 #endif
233 	default:
234 		WARN_ON_ONCE(1);
235 		break;
236 	}
237 
238 	if (hook_head) {
239 		struct nf_hook_state state;
240 
241 		nf_hook_state_init(&state, hook, pf, indev, outdev,
242 				   sk, net, okfn);
243 
244 		ret = nf_hook_slow(skb, &state, hook_head, 0);
245 	}
246 	rcu_read_unlock();
247 
248 	return ret;
249 }
250 
251 /* Activate hook; either okfn or kfree_skb called, unless a hook
252    returns NF_STOLEN (in which case, it's up to the hook to deal with
253    the consequences).
254 
255    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
256    accepted.
257 */
258 
259 /* RR:
260    > I don't want nf_hook to return anything because people might forget
261    > about async and trust the return value to mean "packet was ok".
262 
263    AK:
264    Just document it clearly, then you can expect some sense from kernel
265    coders :)
266 */
267 
268 static inline int
269 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
270 	     struct sk_buff *skb, struct net_device *in, struct net_device *out,
271 	     int (*okfn)(struct net *, struct sock *, struct sk_buff *),
272 	     bool cond)
273 {
274 	int ret;
275 
276 	if (!cond ||
277 	    ((ret = nf_hook(pf, hook, net, sk, skb, in, out, okfn)) == 1))
278 		ret = okfn(net, sk, skb);
279 	return ret;
280 }
281 
282 static inline int
283 NF_HOOK(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk, struct sk_buff *skb,
284 	struct net_device *in, struct net_device *out,
285 	int (*okfn)(struct net *, struct sock *, struct sk_buff *))
286 {
287 	int ret = nf_hook(pf, hook, net, sk, skb, in, out, okfn);
288 	if (ret == 1)
289 		ret = okfn(net, sk, skb);
290 	return ret;
291 }
292 
293 static inline void
294 NF_HOOK_LIST(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
295 	     struct list_head *head, struct net_device *in, struct net_device *out,
296 	     int (*okfn)(struct net *, struct sock *, struct sk_buff *))
297 {
298 	struct sk_buff *skb, *next;
299 	struct list_head sublist;
300 
301 	INIT_LIST_HEAD(&sublist);
302 	list_for_each_entry_safe(skb, next, head, list) {
303 		list_del(&skb->list);
304 		if (nf_hook(pf, hook, net, sk, skb, in, out, okfn) == 1)
305 			list_add_tail(&skb->list, &sublist);
306 	}
307 	/* Put passed packets back on main list */
308 	list_splice(&sublist, head);
309 }
310 
311 /* Call setsockopt() */
312 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
313 		  unsigned int len);
314 int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
315 		  int *len);
316 #ifdef CONFIG_COMPAT
317 int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
318 		char __user *opt, unsigned int len);
319 int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
320 		char __user *opt, int *len);
321 #endif
322 
323 /* Call this before modifying an existing packet: ensures it is
324    modifiable and linear to the point you care about (writable_len).
325    Returns true or false. */
326 int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
327 
328 struct flowi;
329 struct nf_queue_entry;
330 
331 __sum16 nf_checksum(struct sk_buff *skb, unsigned int hook,
332 		    unsigned int dataoff, u_int8_t protocol,
333 		    unsigned short family);
334 
335 __sum16 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
336 			    unsigned int dataoff, unsigned int len,
337 			    u_int8_t protocol, unsigned short family);
338 int nf_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
339 	     bool strict, unsigned short family);
340 int nf_reroute(struct sk_buff *skb, struct nf_queue_entry *entry);
341 
342 #include <net/flow.h>
343 
344 struct nf_conn;
345 enum nf_nat_manip_type;
346 struct nlattr;
347 enum ip_conntrack_dir;
348 
349 struct nf_nat_hook {
350 	int (*parse_nat_setup)(struct nf_conn *ct, enum nf_nat_manip_type manip,
351 			       const struct nlattr *attr);
352 	void (*decode_session)(struct sk_buff *skb, struct flowi *fl);
353 	unsigned int (*manip_pkt)(struct sk_buff *skb, struct nf_conn *ct,
354 				  enum nf_nat_manip_type mtype,
355 				  enum ip_conntrack_dir dir);
356 };
357 
358 extern struct nf_nat_hook __rcu *nf_nat_hook;
359 
360 static inline void
361 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
362 {
363 #ifdef CONFIG_NF_NAT_NEEDED
364 	struct nf_nat_hook *nat_hook;
365 
366 	rcu_read_lock();
367 	nat_hook = rcu_dereference(nf_nat_hook);
368 	if (nat_hook && nat_hook->decode_session)
369 		nat_hook->decode_session(skb, fl);
370 	rcu_read_unlock();
371 #endif
372 }
373 
374 #else /* !CONFIG_NETFILTER */
375 static inline int
376 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
377 	     struct sk_buff *skb, struct net_device *in, struct net_device *out,
378 	     int (*okfn)(struct net *, struct sock *, struct sk_buff *),
379 	     bool cond)
380 {
381 	return okfn(net, sk, skb);
382 }
383 
384 static inline int
385 NF_HOOK(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
386 	struct sk_buff *skb, struct net_device *in, struct net_device *out,
387 	int (*okfn)(struct net *, struct sock *, struct sk_buff *))
388 {
389 	return okfn(net, sk, skb);
390 }
391 
392 static inline void
393 NF_HOOK_LIST(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
394 	     struct list_head *head, struct net_device *in, struct net_device *out,
395 	     int (*okfn)(struct net *, struct sock *, struct sk_buff *))
396 {
397 	/* nothing to do */
398 }
399 
400 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,
401 			  struct sock *sk, struct sk_buff *skb,
402 			  struct net_device *indev, struct net_device *outdev,
403 			  int (*okfn)(struct net *, struct sock *, struct sk_buff *))
404 {
405 	return 1;
406 }
407 struct flowi;
408 static inline void
409 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
410 {
411 }
412 #endif /*CONFIG_NETFILTER*/
413 
414 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
415 #include <linux/netfilter/nf_conntrack_zones_common.h>
416 
417 extern void (*ip_ct_attach)(struct sk_buff *, const struct sk_buff *) __rcu;
418 void nf_ct_attach(struct sk_buff *, const struct sk_buff *);
419 struct nf_conntrack_tuple;
420 bool nf_ct_get_tuple_skb(struct nf_conntrack_tuple *dst_tuple,
421 			 const struct sk_buff *skb);
422 #else
423 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
424 struct nf_conntrack_tuple;
425 static inline bool nf_ct_get_tuple_skb(struct nf_conntrack_tuple *dst_tuple,
426 				       const struct sk_buff *skb)
427 {
428 	return false;
429 }
430 #endif
431 
432 struct nf_conn;
433 enum ip_conntrack_info;
434 
435 struct nf_ct_hook {
436 	int (*update)(struct net *net, struct sk_buff *skb);
437 	void (*destroy)(struct nf_conntrack *);
438 	bool (*get_tuple_skb)(struct nf_conntrack_tuple *,
439 			      const struct sk_buff *);
440 };
441 extern struct nf_ct_hook __rcu *nf_ct_hook;
442 
443 struct nlattr;
444 
445 struct nfnl_ct_hook {
446 	struct nf_conn *(*get_ct)(const struct sk_buff *skb,
447 				  enum ip_conntrack_info *ctinfo);
448 	size_t (*build_size)(const struct nf_conn *ct);
449 	int (*build)(struct sk_buff *skb, struct nf_conn *ct,
450 		     enum ip_conntrack_info ctinfo,
451 		     u_int16_t ct_attr, u_int16_t ct_info_attr);
452 	int (*parse)(const struct nlattr *attr, struct nf_conn *ct);
453 	int (*attach_expect)(const struct nlattr *attr, struct nf_conn *ct,
454 			     u32 portid, u32 report);
455 	void (*seq_adjust)(struct sk_buff *skb, struct nf_conn *ct,
456 			   enum ip_conntrack_info ctinfo, s32 off);
457 };
458 extern struct nfnl_ct_hook __rcu *nfnl_ct_hook;
459 
460 /**
461  * nf_skb_duplicated - TEE target has sent a packet
462  *
463  * When a xtables target sends a packet, the OUTPUT and POSTROUTING
464  * hooks are traversed again, i.e. nft and xtables are invoked recursively.
465  *
466  * This is used by xtables TEE target to prevent the duplicated skb from
467  * being duplicated again.
468  */
469 DECLARE_PER_CPU(bool, nf_skb_duplicated);
470 
471 #endif /*__LINUX_NETFILTER_H*/
472