1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Connection state tracking for netfilter.  This is separated from,
4  * but required by, the (future) NAT layer; it can also be used by an iptables
5  * extension.
6  *
7  * 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
8  *	- generalize L3 protocol dependent part.
9  *
10  * Derived from include/linux/netfiter_ipv4/ip_conntrack.h
11  */
12 
13 #ifndef _NF_CONNTRACK_H
14 #define _NF_CONNTRACK_H
15 
16 #include <linux/bitops.h>
17 #include <linux/compiler.h>
18 
19 #include <linux/netfilter/nf_conntrack_common.h>
20 #include <linux/netfilter/nf_conntrack_tcp.h>
21 #include <linux/netfilter/nf_conntrack_dccp.h>
22 #include <linux/netfilter/nf_conntrack_sctp.h>
23 #include <linux/netfilter/nf_conntrack_proto_gre.h>
24 
25 #include <net/netfilter/nf_conntrack_tuple.h>
26 
27 struct nf_ct_udp {
28 	unsigned long	stream_ts;
29 };
30 
31 /* per conntrack: protocol private data */
32 union nf_conntrack_proto {
33 	/* insert conntrack proto private data here */
34 	struct nf_ct_dccp dccp;
35 	struct ip_ct_sctp sctp;
36 	struct ip_ct_tcp tcp;
37 	struct nf_ct_udp udp;
38 	struct nf_ct_gre gre;
39 	unsigned int tmpl_padto;
40 };
41 
42 union nf_conntrack_expect_proto {
43 	/* insert expect proto private data here */
44 };
45 
46 struct nf_conntrack_net_ecache {
47 	struct delayed_work dwork;
48 	spinlock_t dying_lock;
49 	struct hlist_nulls_head dying_list;
50 };
51 
52 struct nf_conntrack_net {
53 	/* only used when new connection is allocated: */
54 	atomic_t count;
55 	unsigned int expect_count;
56 	u8 sysctl_auto_assign_helper;
57 	bool auto_assign_helper_warned;
58 
59 	/* only used from work queues, configuration plane, and so on: */
60 	unsigned int users4;
61 	unsigned int users6;
62 	unsigned int users_bridge;
63 #ifdef CONFIG_SYSCTL
64 	struct ctl_table_header	*sysctl_header;
65 #endif
66 #ifdef CONFIG_NF_CONNTRACK_EVENTS
67 	struct nf_conntrack_net_ecache ecache;
68 #endif
69 };
70 
71 #include <linux/types.h>
72 #include <linux/skbuff.h>
73 
74 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
75 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
76 
77 struct nf_conn {
78 	/* Usage count in here is 1 for hash table, 1 per skb,
79 	 * plus 1 for any connection(s) we are `master' for
80 	 *
81 	 * Hint, SKB address this struct and refcnt via skb->_nfct and
82 	 * helpers nf_conntrack_get() and nf_conntrack_put().
83 	 * Helper nf_ct_put() equals nf_conntrack_put() by dec refcnt,
84 	 * except that the latter uses internal indirection and does not
85 	 * result in a conntrack module dependency.
86 	 * beware nf_ct_get() is different and don't inc refcnt.
87 	 */
88 	struct nf_conntrack ct_general;
89 
90 	spinlock_t	lock;
91 	/* jiffies32 when this ct is considered dead */
92 	u32 timeout;
93 
94 #ifdef CONFIG_NF_CONNTRACK_ZONES
95 	struct nf_conntrack_zone zone;
96 #endif
97 	/* XXX should I move this to the tail ? - Y.K */
98 	/* These are my tuples; original and reply */
99 	struct nf_conntrack_tuple_hash tuplehash[IP_CT_DIR_MAX];
100 
101 	/* Have we seen traffic both ways yet? (bitset) */
102 	unsigned long status;
103 
104 	possible_net_t ct_net;
105 
106 #if IS_ENABLED(CONFIG_NF_NAT)
107 	struct hlist_node	nat_bysource;
108 #endif
109 	/* all members below initialized via memset */
110 	struct { } __nfct_init_offset;
111 
112 	/* If we were expected by an expectation, this will be it */
113 	struct nf_conn *master;
114 
115 #if defined(CONFIG_NF_CONNTRACK_MARK)
116 	u_int32_t mark;
117 #endif
118 
119 #ifdef CONFIG_NF_CONNTRACK_SECMARK
120 	u_int32_t secmark;
121 #endif
122 
123 	/* Extensions */
124 	struct nf_ct_ext *ext;
125 
126 	/* Storage reserved for other modules, must be the last member */
127 	union nf_conntrack_proto proto;
128 };
129 
130 static inline struct nf_conn *
nf_ct_tuplehash_to_ctrack(const struct nf_conntrack_tuple_hash * hash)131 nf_ct_tuplehash_to_ctrack(const struct nf_conntrack_tuple_hash *hash)
132 {
133 	return container_of(hash, struct nf_conn,
134 			    tuplehash[hash->tuple.dst.dir]);
135 }
136 
nf_ct_l3num(const struct nf_conn * ct)137 static inline u_int16_t nf_ct_l3num(const struct nf_conn *ct)
138 {
139 	return ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
140 }
141 
nf_ct_protonum(const struct nf_conn * ct)142 static inline u_int8_t nf_ct_protonum(const struct nf_conn *ct)
143 {
144 	return ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum;
145 }
146 
147 #define nf_ct_tuple(ct, dir) (&(ct)->tuplehash[dir].tuple)
148 
149 /* get master conntrack via master expectation */
150 #define master_ct(conntr) (conntr->master)
151 
152 extern struct net init_net;
153 
nf_ct_net(const struct nf_conn * ct)154 static inline struct net *nf_ct_net(const struct nf_conn *ct)
155 {
156 	return read_pnet(&ct->ct_net);
157 }
158 
159 /* Alter reply tuple (maybe alter helper). */
160 void nf_conntrack_alter_reply(struct nf_conn *ct,
161 			      const struct nf_conntrack_tuple *newreply);
162 
163 /* Is this tuple taken? (ignoring any belonging to the given
164    conntrack). */
165 int nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple,
166 			     const struct nf_conn *ignored_conntrack);
167 
168 /* Return conntrack_info and tuple hash for given skb. */
169 static inline struct nf_conn *
nf_ct_get(const struct sk_buff * skb,enum ip_conntrack_info * ctinfo)170 nf_ct_get(const struct sk_buff *skb, enum ip_conntrack_info *ctinfo)
171 {
172 	unsigned long nfct = skb_get_nfct(skb);
173 
174 	*ctinfo = nfct & NFCT_INFOMASK;
175 	return (struct nf_conn *)(nfct & NFCT_PTRMASK);
176 }
177 
178 void nf_ct_destroy(struct nf_conntrack *nfct);
179 
180 /* decrement reference count on a conntrack */
nf_ct_put(struct nf_conn * ct)181 static inline void nf_ct_put(struct nf_conn *ct)
182 {
183 	if (ct && refcount_dec_and_test(&ct->ct_general.use))
184 		nf_ct_destroy(&ct->ct_general);
185 }
186 
187 /* Protocol module loading */
188 int nf_ct_l3proto_try_module_get(unsigned short l3proto);
189 void nf_ct_l3proto_module_put(unsigned short l3proto);
190 
191 /* load module; enable/disable conntrack in this namespace */
192 int nf_ct_netns_get(struct net *net, u8 nfproto);
193 void nf_ct_netns_put(struct net *net, u8 nfproto);
194 
195 /*
196  * Allocate a hashtable of hlist_head (if nulls == 0),
197  * or hlist_nulls_head (if nulls == 1)
198  */
199 void *nf_ct_alloc_hashtable(unsigned int *sizep, int nulls);
200 
201 int nf_conntrack_hash_check_insert(struct nf_conn *ct);
202 bool nf_ct_delete(struct nf_conn *ct, u32 pid, int report);
203 
204 bool nf_ct_get_tuplepr(const struct sk_buff *skb, unsigned int nhoff,
205 		       u_int16_t l3num, struct net *net,
206 		       struct nf_conntrack_tuple *tuple);
207 
208 void __nf_ct_refresh_acct(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
209 			  const struct sk_buff *skb,
210 			  u32 extra_jiffies, bool do_acct);
211 
212 /* Refresh conntrack for this many jiffies and do accounting */
nf_ct_refresh_acct(struct nf_conn * ct,enum ip_conntrack_info ctinfo,const struct sk_buff * skb,u32 extra_jiffies)213 static inline void nf_ct_refresh_acct(struct nf_conn *ct,
214 				      enum ip_conntrack_info ctinfo,
215 				      const struct sk_buff *skb,
216 				      u32 extra_jiffies)
217 {
218 	__nf_ct_refresh_acct(ct, ctinfo, skb, extra_jiffies, true);
219 }
220 
221 /* Refresh conntrack for this many jiffies */
nf_ct_refresh(struct nf_conn * ct,const struct sk_buff * skb,u32 extra_jiffies)222 static inline void nf_ct_refresh(struct nf_conn *ct,
223 				 const struct sk_buff *skb,
224 				 u32 extra_jiffies)
225 {
226 	__nf_ct_refresh_acct(ct, 0, skb, extra_jiffies, false);
227 }
228 
229 /* kill conntrack and do accounting */
230 bool nf_ct_kill_acct(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
231 		     const struct sk_buff *skb);
232 
233 /* kill conntrack without accounting */
nf_ct_kill(struct nf_conn * ct)234 static inline bool nf_ct_kill(struct nf_conn *ct)
235 {
236 	return nf_ct_delete(ct, 0, 0);
237 }
238 
239 struct nf_ct_iter_data {
240 	struct net *net;
241 	void *data;
242 	u32 portid;
243 	int report;
244 };
245 
246 /* Iterate over all conntracks: if iter returns true, it's deleted. */
247 void nf_ct_iterate_cleanup_net(int (*iter)(struct nf_conn *i, void *data),
248 			       const struct nf_ct_iter_data *iter_data);
249 
250 /* also set unconfirmed conntracks as dying. Only use in module exit path. */
251 void nf_ct_iterate_destroy(int (*iter)(struct nf_conn *i, void *data),
252 			   void *data);
253 
254 struct nf_conntrack_zone;
255 
256 void nf_conntrack_free(struct nf_conn *ct);
257 struct nf_conn *nf_conntrack_alloc(struct net *net,
258 				   const struct nf_conntrack_zone *zone,
259 				   const struct nf_conntrack_tuple *orig,
260 				   const struct nf_conntrack_tuple *repl,
261 				   gfp_t gfp);
262 
nf_ct_is_template(const struct nf_conn * ct)263 static inline int nf_ct_is_template(const struct nf_conn *ct)
264 {
265 	return test_bit(IPS_TEMPLATE_BIT, &ct->status);
266 }
267 
268 /* It's confirmed if it is, or has been in the hash table. */
nf_ct_is_confirmed(const struct nf_conn * ct)269 static inline int nf_ct_is_confirmed(const struct nf_conn *ct)
270 {
271 	return test_bit(IPS_CONFIRMED_BIT, &ct->status);
272 }
273 
nf_ct_is_dying(const struct nf_conn * ct)274 static inline int nf_ct_is_dying(const struct nf_conn *ct)
275 {
276 	return test_bit(IPS_DYING_BIT, &ct->status);
277 }
278 
279 /* Packet is received from loopback */
nf_is_loopback_packet(const struct sk_buff * skb)280 static inline bool nf_is_loopback_packet(const struct sk_buff *skb)
281 {
282 	return skb->dev && skb->skb_iif && skb->dev->flags & IFF_LOOPBACK;
283 }
284 
285 #define nfct_time_stamp ((u32)(jiffies))
286 
287 /* jiffies until ct expires, 0 if already expired */
nf_ct_expires(const struct nf_conn * ct)288 static inline unsigned long nf_ct_expires(const struct nf_conn *ct)
289 {
290 	s32 timeout = READ_ONCE(ct->timeout) - nfct_time_stamp;
291 
292 	return max(timeout, 0);
293 }
294 
nf_ct_is_expired(const struct nf_conn * ct)295 static inline bool nf_ct_is_expired(const struct nf_conn *ct)
296 {
297 	return (__s32)(READ_ONCE(ct->timeout) - nfct_time_stamp) <= 0;
298 }
299 
300 /* use after obtaining a reference count */
nf_ct_should_gc(const struct nf_conn * ct)301 static inline bool nf_ct_should_gc(const struct nf_conn *ct)
302 {
303 	return nf_ct_is_expired(ct) && nf_ct_is_confirmed(ct) &&
304 	       !nf_ct_is_dying(ct);
305 }
306 
307 #define	NF_CT_DAY	(86400 * HZ)
308 
309 /* Set an arbitrary timeout large enough not to ever expire, this save
310  * us a check for the IPS_OFFLOAD_BIT from the packet path via
311  * nf_ct_is_expired().
312  */
nf_ct_offload_timeout(struct nf_conn * ct)313 static inline void nf_ct_offload_timeout(struct nf_conn *ct)
314 {
315 	if (nf_ct_expires(ct) < NF_CT_DAY / 2)
316 		WRITE_ONCE(ct->timeout, nfct_time_stamp + NF_CT_DAY);
317 }
318 
319 struct kernel_param;
320 
321 int nf_conntrack_set_hashsize(const char *val, const struct kernel_param *kp);
322 int nf_conntrack_hash_resize(unsigned int hashsize);
323 
324 extern struct hlist_nulls_head *nf_conntrack_hash;
325 extern unsigned int nf_conntrack_htable_size;
326 extern seqcount_spinlock_t nf_conntrack_generation;
327 extern unsigned int nf_conntrack_max;
328 
329 /* must be called with rcu read lock held */
330 static inline void
nf_conntrack_get_ht(struct hlist_nulls_head ** hash,unsigned int * hsize)331 nf_conntrack_get_ht(struct hlist_nulls_head **hash, unsigned int *hsize)
332 {
333 	struct hlist_nulls_head *hptr;
334 	unsigned int sequence, hsz;
335 
336 	do {
337 		sequence = read_seqcount_begin(&nf_conntrack_generation);
338 		hsz = nf_conntrack_htable_size;
339 		hptr = nf_conntrack_hash;
340 	} while (read_seqcount_retry(&nf_conntrack_generation, sequence));
341 
342 	*hash = hptr;
343 	*hsize = hsz;
344 }
345 
346 struct nf_conn *nf_ct_tmpl_alloc(struct net *net,
347 				 const struct nf_conntrack_zone *zone,
348 				 gfp_t flags);
349 void nf_ct_tmpl_free(struct nf_conn *tmpl);
350 
351 u32 nf_ct_get_id(const struct nf_conn *ct);
352 u32 nf_conntrack_count(const struct net *net);
353 
354 static inline void
nf_ct_set(struct sk_buff * skb,struct nf_conn * ct,enum ip_conntrack_info info)355 nf_ct_set(struct sk_buff *skb, struct nf_conn *ct, enum ip_conntrack_info info)
356 {
357 	skb_set_nfct(skb, (unsigned long)ct | info);
358 }
359 
360 extern unsigned int nf_conntrack_net_id;
361 
nf_ct_pernet(const struct net * net)362 static inline struct nf_conntrack_net *nf_ct_pernet(const struct net *net)
363 {
364 	return net_generic(net, nf_conntrack_net_id);
365 }
366 
367 #define NF_CT_STAT_INC(net, count)	  __this_cpu_inc((net)->ct.stat->count)
368 #define NF_CT_STAT_INC_ATOMIC(net, count) this_cpu_inc((net)->ct.stat->count)
369 #define NF_CT_STAT_ADD_ATOMIC(net, count, v) this_cpu_add((net)->ct.stat->count, (v))
370 
371 #define MODULE_ALIAS_NFCT_HELPER(helper) \
372         MODULE_ALIAS("nfct-helper-" helper)
373 
374 #endif /* _NF_CONNTRACK_H */
375