netfilter.h

  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/module.h>
 15#include <linux/netfilter_defs.h>
 16#include <linux/netdevice.h>
 17#include <linux/sockptr.h>
 18#include <net/net_namespace.h>
 19
 20static inline int NF_DROP_GETERR(int verdict)
 21{
 22	return -(verdict >> NF_VERDICT_QBITS);
 23}
 24
 25static __always_inline int
 26NF_DROP_REASON(struct sk_buff *skb, enum skb_drop_reason reason, u32 err)
 27{
 28	BUILD_BUG_ON(err > 0xffff);
 29
 30	kfree_skb_reason(skb, reason);
 31
 32	return ((err << 16) | NF_STOLEN);
 33}
 34
 35static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
 36				   const union nf_inet_addr *a2)
 37{
 38#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
 39	const unsigned long *ul1 = (const unsigned long *)a1;
 40	const unsigned long *ul2 = (const unsigned long *)a2;
 41
 42	return ((ul1[0] ^ ul2[0]) | (ul1[1] ^ ul2[1])) == 0UL;
 43#else
 44	return a1->all[0] == a2->all[0] &&
 45	       a1->all[1] == a2->all[1] &&
 46	       a1->all[2] == a2->all[2] &&
 47	       a1->all[3] == a2->all[3];
 48#endif
 49}
 50
 51static inline void nf_inet_addr_mask(const union nf_inet_addr *a1,
 52				     union nf_inet_addr *result,
 53				     const union nf_inet_addr *mask)
 54{
 55#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
 56	const unsigned long *ua = (const unsigned long *)a1;
 57	unsigned long *ur = (unsigned long *)result;
 58	const unsigned long *um = (const unsigned long *)mask;
 59
 60	ur[0] = ua[0] & um[0];
 61	ur[1] = ua[1] & um[1];
 62#else
 63	result->all[0] = a1->all[0] & mask->all[0];
 64	result->all[1] = a1->all[1] & mask->all[1];
 65	result->all[2] = a1->all[2] & mask->all[2];
 66	result->all[3] = a1->all[3] & mask->all[3];
 67#endif
 68}
 69
 70int netfilter_init(void);
 71
 72struct sk_buff;
 73
 74struct nf_hook_ops;
 75
 76struct sock;
 77
 78struct nf_hook_state {
 79	u8 hook;
 80	u8 pf;
 81	struct net_device *in;
 82	struct net_device *out;
 83	struct sock *sk;
 84	struct net *net;
 85	int (*okfn)(struct net *, struct sock *, struct sk_buff *);
 86};
 87
 88typedef unsigned int nf_hookfn(void *priv,
 89			       struct sk_buff *skb,
 90			       const struct nf_hook_state *state);
 91enum nf_hook_ops_type {
 92	NF_HOOK_OP_UNDEFINED,
 93	NF_HOOK_OP_NF_TABLES,
 94	NF_HOOK_OP_BPF,
 95	NF_HOOK_OP_NFT_FT,
 96};
 97
 98struct nf_hook_ops {
 99	struct list_head	list;
100	struct rcu_head		rcu;
101
102	/* User fills in from here down. */
103	nf_hookfn		*hook;
104	struct net_device	*dev;
105	void			*priv;
106	u8			pf;
107	enum nf_hook_ops_type	hook_ops_type:8;
108	unsigned int		hooknum;
109	/* Hooks are ordered in ascending priority. */
110	int			priority;
111};
112
113struct nf_hook_entry {
114	nf_hookfn			*hook;
115	void				*priv;
116};
117
118struct nf_hook_entries_rcu_head {
119	struct rcu_head head;
120	void	*allocation;
121};
122
123struct nf_hook_entries {
124	u16				num_hook_entries;
125	/* padding */
126	struct nf_hook_entry		hooks[];
127
128	/* trailer: pointers to original orig_ops of each hook,
129	 * followed by rcu_head and scratch space used for freeing
130	 * the structure via call_rcu.
131	 *
132	 *   This is not part of struct nf_hook_entry since its only
133	 *   needed in slow path (hook register/unregister):
134	 * const struct nf_hook_ops     *orig_ops[]
135	 *
136	 *   For the same reason, we store this at end -- its
137	 *   only needed when a hook is deleted, not during
138	 *   packet path processing:
139	 * struct nf_hook_entries_rcu_head     head
140	 */
141};
142
143#ifdef CONFIG_NETFILTER
144static inline struct nf_hook_ops **nf_hook_entries_get_hook_ops(const struct nf_hook_entries *e)
145{
146	unsigned int n = e->num_hook_entries;
147	const void *hook_end;
148
149	hook_end = &e->hooks[n]; /* this is *past* ->hooks[]! */
150
151	return (struct nf_hook_ops **)hook_end;
152}
153
154static inline int
155nf_hook_entry_hookfn(const struct nf_hook_entry *entry, struct sk_buff *skb,
156		     struct nf_hook_state *state)
157{
158	return entry->hook(entry->priv, skb, state);
159}
160
161static inline void nf_hook_state_init(struct nf_hook_state *p,
162				      unsigned int hook,
163				      u_int8_t pf,
164				      struct net_device *indev,
165				      struct net_device *outdev,
166				      struct sock *sk,
167				      struct net *net,
168				      int (*okfn)(struct net *, struct sock *, struct sk_buff *))
169{
170	p->hook = hook;
171	p->pf = pf;
172	p->in = indev;
173	p->out = outdev;
174	p->sk = sk;
175	p->net = net;
176	p->okfn = okfn;
177}
178
179
180
181struct nf_sockopt_ops {
182	struct list_head list;
183
184	u_int8_t pf;
185
186	/* Non-inclusive ranges: use 0/0/NULL to never get called. */
187	int set_optmin;
188	int set_optmax;
189	int (*set)(struct sock *sk, int optval, sockptr_t arg,
190		   unsigned int len);
191	int get_optmin;
192	int get_optmax;
193	int (*get)(struct sock *sk, int optval, void __user *user, int *len);
194	/* Use the module struct to lock set/get code in place */
195	struct module *owner;
196};
197
198/* Function to register/unregister hook points. */
199int nf_register_net_hook(struct net *net, const struct nf_hook_ops *ops);
200void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *ops);
201int nf_register_net_hooks(struct net *net, const struct nf_hook_ops *reg,
202			  unsigned int n);
203void nf_unregister_net_hooks(struct net *net, const struct nf_hook_ops *reg,
204			     unsigned int n);
205
206/* Functions to register get/setsockopt ranges (non-inclusive).  You
207   need to check permissions yourself! */
208int nf_register_sockopt(struct nf_sockopt_ops *reg);
209void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
210
211#ifdef CONFIG_JUMP_LABEL
212extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
213#endif
214
215int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state,
216		 const struct nf_hook_entries *e, unsigned int i);
217
218void nf_hook_slow_list(struct list_head *head, struct nf_hook_state *state,
219		       const struct nf_hook_entries *e);
220/**
221 *	nf_hook - call a netfilter hook
222 *
223 *	Returns 1 if the hook has allowed the packet to pass.  The function
224 *	okfn must be invoked by the caller in this case.  Any other return
225 *	value indicates the packet has been consumed by the hook.
226 */
227static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,
228			  struct sock *sk, struct sk_buff *skb,
229			  struct net_device *indev, struct net_device *outdev,
230			  int (*okfn)(struct net *, struct sock *, struct sk_buff *))
231{
232	struct nf_hook_entries *hook_head = NULL;
233	int ret = 1;
234
235#ifdef CONFIG_JUMP_LABEL
236	if (__builtin_constant_p(pf) &&
237	    __builtin_constant_p(hook) &&
238	    !static_key_false(&nf_hooks_needed[pf][hook]))
239		return 1;
240#endif
241
242	rcu_read_lock();
243	switch (pf) {
244	case NFPROTO_IPV4:
245		hook_head = rcu_dereference(net->nf.hooks_ipv4[hook]);
246		break;
247	case NFPROTO_IPV6:
248		hook_head = rcu_dereference(net->nf.hooks_ipv6[hook]);
249		break;
250	case NFPROTO_ARP:
251#ifdef CONFIG_NETFILTER_FAMILY_ARP
252		if (WARN_ON_ONCE(hook >= ARRAY_SIZE(net->nf.hooks_arp)))
253			break;
254		hook_head = rcu_dereference(net->nf.hooks_arp[hook]);
255#endif
256		break;
257	case NFPROTO_BRIDGE:
258#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
259		hook_head = rcu_dereference(net->nf.hooks_bridge[hook]);
260#endif
261		break;
262	default:
263		WARN_ON_ONCE(1);
264		break;
265	}
266
267	if (hook_head) {
268		struct nf_hook_state state;
269
270		nf_hook_state_init(&state, hook, pf, indev, outdev,
271				   sk, net, okfn);
272
273		ret = nf_hook_slow(skb, &state, hook_head, 0);
274	}
275	rcu_read_unlock();
276
277	return ret;
278}
279
280/* Activate hook; either okfn or kfree_skb called, unless a hook
281   returns NF_STOLEN (in which case, it's up to the hook to deal with
282   the consequences).
283
284   Returns -ERRNO if packet dropped.  Zero means queued, stolen or
285   accepted.
286*/
287
288/* RR:
289   > I don't want nf_hook to return anything because people might forget
290   > about async and trust the return value to mean "packet was ok".
291
292   AK:
293   Just document it clearly, then you can expect some sense from kernel
294   coders :)
295*/
296
297static inline int
298NF_HOOK_COND(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
299	     struct sk_buff *skb, struct net_device *in, struct net_device *out,
300	     int (*okfn)(struct net *, struct sock *, struct sk_buff *),
301	     bool cond)
302{
303	int ret;
304
305	if (!cond ||
306	    ((ret = nf_hook(pf, hook, net, sk, skb, in, out, okfn)) == 1))
307		ret = okfn(net, sk, skb);
308	return ret;
309}
310
311static inline int
312NF_HOOK(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk, struct sk_buff *skb,
313	struct net_device *in, struct net_device *out,
314	int (*okfn)(struct net *, struct sock *, struct sk_buff *))
315{
316	int ret = nf_hook(pf, hook, net, sk, skb, in, out, okfn);
317	if (ret == 1)
318		ret = okfn(net, sk, skb);
319	return ret;
320}
321
322static inline void
323NF_HOOK_LIST(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
324	     struct list_head *head, struct net_device *in, struct net_device *out,
325	     int (*okfn)(struct net *, struct sock *, struct sk_buff *))
326{
327	struct nf_hook_entries *hook_head = NULL;
328
329#ifdef CONFIG_JUMP_LABEL
330	if (__builtin_constant_p(pf) &&
331	    __builtin_constant_p(hook) &&
332	    !static_key_false(&nf_hooks_needed[pf][hook]))
333		return;
334#endif
335
336	rcu_read_lock();
337	switch (pf) {
338	case NFPROTO_IPV4:
339		hook_head = rcu_dereference(net->nf.hooks_ipv4[hook]);
340		break;
341	case NFPROTO_IPV6:
342		hook_head = rcu_dereference(net->nf.hooks_ipv6[hook]);
343		break;
344	default:
345		WARN_ON_ONCE(1);
346		break;
347	}
348
349	if (hook_head) {
350		struct nf_hook_state state;
351
352		nf_hook_state_init(&state, hook, pf, in, out, sk, net, okfn);
353
354		nf_hook_slow_list(head, &state, hook_head);
355	}
356	rcu_read_unlock();
357}
358
359/* Call setsockopt() */
360int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, sockptr_t opt,
361		  unsigned int len);
362int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
363		  int *len);
364
365struct flowi;
366struct nf_queue_entry;
367
368__sum16 nf_checksum(struct sk_buff *skb, unsigned int hook,
369		    unsigned int dataoff, u_int8_t protocol,
370		    unsigned short family);
371
372__sum16 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
373			    unsigned int dataoff, unsigned int len,
374			    u_int8_t protocol, unsigned short family);
375int nf_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
376	     bool strict, unsigned short family);
377
378#include <net/flow.h>
379
380struct nf_conn;
381enum nf_nat_manip_type;
382struct nlattr;
383
384struct nf_nat_hook {
385	int (*parse_nat_setup)(struct nf_conn *ct, enum nf_nat_manip_type manip,
386			       const struct nlattr *attr);
387	void (*decode_session)(struct sk_buff *skb, struct flowi *fl);
388	void (*remove_nat_bysrc)(struct nf_conn *ct);
389};
390
391extern const struct nf_nat_hook __rcu *nf_nat_hook;
392
393static inline void
394nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
395{
396#if IS_ENABLED(CONFIG_NF_NAT)
397	const struct nf_nat_hook *nat_hook;
398
399	rcu_read_lock();
400	nat_hook = rcu_dereference(nf_nat_hook);
401	if (nat_hook && nat_hook->decode_session)
402		nat_hook->decode_session(skb, fl);
403	rcu_read_unlock();
404#endif
405}
406
407#else /* !CONFIG_NETFILTER */
408static inline int
409NF_HOOK_COND(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
410	     struct sk_buff *skb, struct net_device *in, struct net_device *out,
411	     int (*okfn)(struct net *, struct sock *, struct sk_buff *),
412	     bool cond)
413{
414	return okfn(net, sk, skb);
415}
416
417static inline int
418NF_HOOK(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
419	struct sk_buff *skb, struct net_device *in, struct net_device *out,
420	int (*okfn)(struct net *, struct sock *, struct sk_buff *))
421{
422	return okfn(net, sk, skb);
423}
424
425static inline void
426NF_HOOK_LIST(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
427	     struct list_head *head, struct net_device *in, struct net_device *out,
428	     int (*okfn)(struct net *, struct sock *, struct sk_buff *))
429{
430	/* nothing to do */
431}
432
433static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,
434			  struct sock *sk, struct sk_buff *skb,
435			  struct net_device *indev, struct net_device *outdev,
436			  int (*okfn)(struct net *, struct sock *, struct sk_buff *))
437{
438	return 1;
439}
440struct flowi;
441static inline void
442nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
443{
444}
445#endif /*CONFIG_NETFILTER*/
446
447#if IS_ENABLED(CONFIG_NF_CONNTRACK)
448#include <linux/netfilter/nf_conntrack_zones_common.h>
449
450void nf_ct_attach(struct sk_buff *, const struct sk_buff *);
451void nf_ct_set_closing(struct nf_conntrack *nfct);
452struct nf_conntrack_tuple;
453bool nf_ct_get_tuple_skb(struct nf_conntrack_tuple *dst_tuple,
454			 const struct sk_buff *skb);
455#else
456static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
457static inline void nf_ct_set_closing(struct nf_conntrack *nfct) {}
458struct nf_conntrack_tuple;
459static inline bool nf_ct_get_tuple_skb(struct nf_conntrack_tuple *dst_tuple,
460				       const struct sk_buff *skb)
461{
462	return false;
463}
464#endif
465
466struct nf_conn;
467enum ip_conntrack_info;
468
469struct nf_ct_hook {
470	int (*update)(struct net *net, struct sk_buff *skb);
471	void (*destroy)(struct nf_conntrack *);
472	bool (*get_tuple_skb)(struct nf_conntrack_tuple *,
473			      const struct sk_buff *);
474	void (*attach)(struct sk_buff *nskb, const struct sk_buff *skb);
475	void (*set_closing)(struct nf_conntrack *nfct);
476	int (*confirm)(struct sk_buff *skb);
477	u32 (*get_id)(const struct nf_conntrack *nfct);
478};
479extern const struct nf_ct_hook __rcu *nf_ct_hook;
480
481struct nlattr;
482
483struct nfnl_ct_hook {
484	size_t (*build_size)(const struct nf_conn *ct);
485	int (*build)(struct sk_buff *skb, struct nf_conn *ct,
486		     enum ip_conntrack_info ctinfo,
487		     u_int16_t ct_attr, u_int16_t ct_info_attr);
488	int (*parse)(const struct nlattr *attr, struct nf_conn *ct);
489	int (*attach_expect)(const struct nlattr *attr, struct nf_conn *ct,
490			     u32 portid, u32 report);
491	void (*seq_adjust)(struct sk_buff *skb, struct nf_conn *ct,
492			   enum ip_conntrack_info ctinfo, s32 off);
493};
494extern const struct nfnl_ct_hook __rcu *nfnl_ct_hook;
495
496struct nf_defrag_hook {
497	struct module *owner;
498	int (*enable)(struct net *net);
499	void (*disable)(struct net *net);
500};
501
502extern const struct nf_defrag_hook __rcu *nf_defrag_v4_hook;
503extern const struct nf_defrag_hook __rcu *nf_defrag_v6_hook;
504
505/*
506 * Contains bitmask of ctnetlink event subscribers, if any.
507 * Can't be pernet due to NETLINK_LISTEN_ALL_NSID setsockopt flag.
508 */
509extern u8 nf_ctnetlink_has_listener;
510#endif /*__LINUX_NETFILTER_H*/