1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3  * INET		An implementation of the TCP/IP protocol suite for the LINUX
4  *		operating system.  INET is implemented using the BSD Socket
5  *		interface as the means of communication with the user level.
6  *
7  * Authors:	Lotsa people, from code originally in tcp
8  */
9 
10 #ifndef _INET_HASHTABLES_H
11 #define _INET_HASHTABLES_H
12 
13 
14 #include <linux/interrupt.h>
15 #include <linux/ip.h>
16 #include <linux/ipv6.h>
17 #include <linux/list.h>
18 #include <linux/slab.h>
19 #include <linux/socket.h>
20 #include <linux/spinlock.h>
21 #include <linux/types.h>
22 #include <linux/wait.h>
23 
24 #include <net/inet_connection_sock.h>
25 #include <net/inet_sock.h>
26 #include <net/sock.h>
27 #include <net/route.h>
28 #include <net/tcp_states.h>
29 #include <net/netns/hash.h>
30 
31 #include <linux/refcount.h>
32 #include <asm/byteorder.h>
33 
34 /* This is for all connections with a full identity, no wildcards.
35  * The 'e' prefix stands for Establish, but we really put all sockets
36  * but LISTEN ones.
37  */
38 struct inet_ehash_bucket {
39 	struct hlist_nulls_head chain;
40 };
41 
42 /* There are a few simple rules, which allow for local port reuse by
43  * an application.  In essence:
44  *
45  *	1) Sockets bound to different interfaces may share a local port.
46  *	   Failing that, goto test 2.
47  *	2) If all sockets have sk->sk_reuse set, and none of them are in
48  *	   TCP_LISTEN state, the port may be shared.
49  *	   Failing that, goto test 3.
50  *	3) If all sockets are bound to a specific inet_sk(sk)->rcv_saddr local
51  *	   address, and none of them are the same, the port may be
52  *	   shared.
53  *	   Failing this, the port cannot be shared.
54  *
55  * The interesting point, is test #2.  This is what an FTP server does
56  * all day.  To optimize this case we use a specific flag bit defined
57  * below.  As we add sockets to a bind bucket list, we perform a
58  * check of: (newsk->sk_reuse && (newsk->sk_state != TCP_LISTEN))
59  * As long as all sockets added to a bind bucket pass this test,
60  * the flag bit will be set.
61  * The resulting situation is that tcp_v[46]_verify_bind() can just check
62  * for this flag bit, if it is set and the socket trying to bind has
63  * sk->sk_reuse set, we don't even have to walk the owners list at all,
64  * we return that it is ok to bind this socket to the requested local port.
65  *
66  * Sounds like a lot of work, but it is worth it.  In a more naive
67  * implementation (ie. current FreeBSD etc.) the entire list of ports
68  * must be walked for each data port opened by an ftp server.  Needless
69  * to say, this does not scale at all.  With a couple thousand FTP
70  * users logged onto your box, isn't it nice to know that new data
71  * ports are created in O(1) time?  I thought so. ;-)	-DaveM
72  */
73 #define FASTREUSEPORT_ANY	1
74 #define FASTREUSEPORT_STRICT	2
75 
76 struct inet_bind_bucket {
77 	possible_net_t		ib_net;
78 	int			l3mdev;
79 	unsigned short		port;
80 	signed char		fastreuse;
81 	signed char		fastreuseport;
82 	kuid_t			fastuid;
83 #if IS_ENABLED(CONFIG_IPV6)
84 	struct in6_addr		fast_v6_rcv_saddr;
85 #endif
86 	__be32			fast_rcv_saddr;
87 	unsigned short		fast_sk_family;
88 	bool			fast_ipv6_only;
89 	struct hlist_node	node;
90 	struct hlist_head	owners;
91 };
92 
ib_net(struct inet_bind_bucket * ib)93 static inline struct net *ib_net(struct inet_bind_bucket *ib)
94 {
95 	return read_pnet(&ib->ib_net);
96 }
97 
98 #define inet_bind_bucket_for_each(tb, head) \
99 	hlist_for_each_entry(tb, head, node)
100 
101 struct inet_bind_hashbucket {
102 	spinlock_t		lock;
103 	struct hlist_head	chain;
104 };
105 
106 /* Sockets can be hashed in established or listening table.
107  * We must use different 'nulls' end-of-chain value for all hash buckets :
108  * A socket might transition from ESTABLISH to LISTEN state without
109  * RCU grace period. A lookup in ehash table needs to handle this case.
110  */
111 #define LISTENING_NULLS_BASE (1U << 29)
112 struct inet_listen_hashbucket {
113 	spinlock_t		lock;
114 	struct hlist_nulls_head	nulls_head;
115 };
116 
117 /* This is for listening sockets, thus all sockets which possess wildcards. */
118 #define INET_LHTABLE_SIZE	32	/* Yes, really, this is all you need. */
119 
120 struct inet_hashinfo {
121 	/* This is for sockets with full identity only.  Sockets here will
122 	 * always be without wildcards and will have the following invariant:
123 	 *
124 	 *          TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE
125 	 *
126 	 */
127 	struct inet_ehash_bucket	*ehash;
128 	spinlock_t			*ehash_locks;
129 	unsigned int			ehash_mask;
130 	unsigned int			ehash_locks_mask;
131 
132 	/* Ok, let's try this, I give up, we do need a local binding
133 	 * TCP hash as well as the others for fast bind/connect.
134 	 */
135 	struct kmem_cache		*bind_bucket_cachep;
136 	struct inet_bind_hashbucket	*bhash;
137 	unsigned int			bhash_size;
138 
139 	/* The 2nd listener table hashed by local port and address */
140 	unsigned int			lhash2_mask;
141 	struct inet_listen_hashbucket	*lhash2;
142 };
143 
144 static inline struct inet_listen_hashbucket *
inet_lhash2_bucket(struct inet_hashinfo * h,u32 hash)145 inet_lhash2_bucket(struct inet_hashinfo *h, u32 hash)
146 {
147 	return &h->lhash2[hash & h->lhash2_mask];
148 }
149 
inet_ehash_bucket(struct inet_hashinfo * hashinfo,unsigned int hash)150 static inline struct inet_ehash_bucket *inet_ehash_bucket(
151 	struct inet_hashinfo *hashinfo,
152 	unsigned int hash)
153 {
154 	return &hashinfo->ehash[hash & hashinfo->ehash_mask];
155 }
156 
inet_ehash_lockp(struct inet_hashinfo * hashinfo,unsigned int hash)157 static inline spinlock_t *inet_ehash_lockp(
158 	struct inet_hashinfo *hashinfo,
159 	unsigned int hash)
160 {
161 	return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask];
162 }
163 
164 int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo);
165 
inet_hashinfo2_free_mod(struct inet_hashinfo * h)166 static inline void inet_hashinfo2_free_mod(struct inet_hashinfo *h)
167 {
168 	kfree(h->lhash2);
169 	h->lhash2 = NULL;
170 }
171 
inet_ehash_locks_free(struct inet_hashinfo * hashinfo)172 static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo)
173 {
174 	kvfree(hashinfo->ehash_locks);
175 	hashinfo->ehash_locks = NULL;
176 }
177 
178 struct inet_bind_bucket *
179 inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net,
180 			struct inet_bind_hashbucket *head,
181 			const unsigned short snum, int l3mdev);
182 void inet_bind_bucket_destroy(struct kmem_cache *cachep,
183 			      struct inet_bind_bucket *tb);
184 
inet_bhashfn(const struct net * net,const __u16 lport,const u32 bhash_size)185 static inline u32 inet_bhashfn(const struct net *net, const __u16 lport,
186 			       const u32 bhash_size)
187 {
188 	return (lport + net_hash_mix(net)) & (bhash_size - 1);
189 }
190 
191 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
192 		    const unsigned short snum);
193 
194 /* Caller must disable local BH processing. */
195 int __inet_inherit_port(const struct sock *sk, struct sock *child);
196 
197 void inet_put_port(struct sock *sk);
198 
199 void inet_hashinfo2_init(struct inet_hashinfo *h, const char *name,
200 			 unsigned long numentries, int scale,
201 			 unsigned long low_limit,
202 			 unsigned long high_limit);
203 int inet_hashinfo2_init_mod(struct inet_hashinfo *h);
204 
205 bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk);
206 bool inet_ehash_nolisten(struct sock *sk, struct sock *osk,
207 			 bool *found_dup_sk);
208 int __inet_hash(struct sock *sk, struct sock *osk);
209 int inet_hash(struct sock *sk);
210 void inet_unhash(struct sock *sk);
211 
212 struct sock *__inet_lookup_listener(struct net *net,
213 				    struct inet_hashinfo *hashinfo,
214 				    struct sk_buff *skb, int doff,
215 				    const __be32 saddr, const __be16 sport,
216 				    const __be32 daddr,
217 				    const unsigned short hnum,
218 				    const int dif, const int sdif);
219 
inet_lookup_listener(struct net * net,struct inet_hashinfo * hashinfo,struct sk_buff * skb,int doff,__be32 saddr,__be16 sport,__be32 daddr,__be16 dport,int dif,int sdif)220 static inline struct sock *inet_lookup_listener(struct net *net,
221 		struct inet_hashinfo *hashinfo,
222 		struct sk_buff *skb, int doff,
223 		__be32 saddr, __be16 sport,
224 		__be32 daddr, __be16 dport, int dif, int sdif)
225 {
226 	return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, sport,
227 				      daddr, ntohs(dport), dif, sdif);
228 }
229 
230 /* Socket demux engine toys. */
231 /* What happens here is ugly; there's a pair of adjacent fields in
232    struct inet_sock; __be16 dport followed by __u16 num.  We want to
233    search by pair, so we combine the keys into a single 32bit value
234    and compare with 32bit value read from &...->dport.  Let's at least
235    make sure that it's not mixed with anything else...
236    On 64bit targets we combine comparisons with pair of adjacent __be32
237    fields in the same way.
238 */
239 #ifdef __BIG_ENDIAN
240 #define INET_COMBINED_PORTS(__sport, __dport) \
241 	((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport)))
242 #else /* __LITTLE_ENDIAN */
243 #define INET_COMBINED_PORTS(__sport, __dport) \
244 	((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport)))
245 #endif
246 
247 #ifdef __BIG_ENDIAN
248 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
249 	const __addrpair __name = (__force __addrpair) ( \
250 				   (((__force __u64)(__be32)(__saddr)) << 32) | \
251 				   ((__force __u64)(__be32)(__daddr)))
252 #else /* __LITTLE_ENDIAN */
253 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
254 	const __addrpair __name = (__force __addrpair) ( \
255 				   (((__force __u64)(__be32)(__daddr)) << 32) | \
256 				   ((__force __u64)(__be32)(__saddr)))
257 #endif /* __BIG_ENDIAN */
258 
inet_match(struct net * net,const struct sock * sk,const __addrpair cookie,const __portpair ports,int dif,int sdif)259 static inline bool inet_match(struct net *net, const struct sock *sk,
260 			      const __addrpair cookie, const __portpair ports,
261 			      int dif, int sdif)
262 {
263 	if (!net_eq(sock_net(sk), net) ||
264 	    sk->sk_portpair != ports ||
265 	    sk->sk_addrpair != cookie)
266 	        return false;
267 
268 	/* READ_ONCE() paired with WRITE_ONCE() in sock_bindtoindex_locked() */
269 	return inet_sk_bound_dev_eq(net, READ_ONCE(sk->sk_bound_dev_if), dif,
270 				    sdif);
271 }
272 
273 /* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need
274  * not check it for lookups anymore, thanks Alexey. -DaveM
275  */
276 struct sock *__inet_lookup_established(struct net *net,
277 				       struct inet_hashinfo *hashinfo,
278 				       const __be32 saddr, const __be16 sport,
279 				       const __be32 daddr, const u16 hnum,
280 				       const int dif, const int sdif);
281 
282 static inline struct sock *
inet_lookup_established(struct net * net,struct inet_hashinfo * hashinfo,const __be32 saddr,const __be16 sport,const __be32 daddr,const __be16 dport,const int dif)283 	inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo,
284 				const __be32 saddr, const __be16 sport,
285 				const __be32 daddr, const __be16 dport,
286 				const int dif)
287 {
288 	return __inet_lookup_established(net, hashinfo, saddr, sport, daddr,
289 					 ntohs(dport), dif, 0);
290 }
291 
__inet_lookup(struct net * net,struct inet_hashinfo * hashinfo,struct sk_buff * skb,int doff,const __be32 saddr,const __be16 sport,const __be32 daddr,const __be16 dport,const int dif,const int sdif,bool * refcounted)292 static inline struct sock *__inet_lookup(struct net *net,
293 					 struct inet_hashinfo *hashinfo,
294 					 struct sk_buff *skb, int doff,
295 					 const __be32 saddr, const __be16 sport,
296 					 const __be32 daddr, const __be16 dport,
297 					 const int dif, const int sdif,
298 					 bool *refcounted)
299 {
300 	u16 hnum = ntohs(dport);
301 	struct sock *sk;
302 
303 	sk = __inet_lookup_established(net, hashinfo, saddr, sport,
304 				       daddr, hnum, dif, sdif);
305 	*refcounted = true;
306 	if (sk)
307 		return sk;
308 	*refcounted = false;
309 	return __inet_lookup_listener(net, hashinfo, skb, doff, saddr,
310 				      sport, daddr, hnum, dif, sdif);
311 }
312 
inet_lookup(struct net * net,struct inet_hashinfo * hashinfo,struct sk_buff * skb,int doff,const __be32 saddr,const __be16 sport,const __be32 daddr,const __be16 dport,const int dif)313 static inline struct sock *inet_lookup(struct net *net,
314 				       struct inet_hashinfo *hashinfo,
315 				       struct sk_buff *skb, int doff,
316 				       const __be32 saddr, const __be16 sport,
317 				       const __be32 daddr, const __be16 dport,
318 				       const int dif)
319 {
320 	struct sock *sk;
321 	bool refcounted;
322 
323 	sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,
324 			   dport, dif, 0, &refcounted);
325 
326 	if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt))
327 		sk = NULL;
328 	return sk;
329 }
330 
__inet_lookup_skb(struct inet_hashinfo * hashinfo,struct sk_buff * skb,int doff,const __be16 sport,const __be16 dport,const int sdif,bool * refcounted)331 static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo,
332 					     struct sk_buff *skb,
333 					     int doff,
334 					     const __be16 sport,
335 					     const __be16 dport,
336 					     const int sdif,
337 					     bool *refcounted)
338 {
339 	struct sock *sk = skb_steal_sock(skb, refcounted);
340 	const struct iphdr *iph = ip_hdr(skb);
341 
342 	if (sk)
343 		return sk;
344 
345 	return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb,
346 			     doff, iph->saddr, sport,
347 			     iph->daddr, dport, inet_iif(skb), sdif,
348 			     refcounted);
349 }
350 
351 u32 inet6_ehashfn(const struct net *net,
352 		  const struct in6_addr *laddr, const u16 lport,
353 		  const struct in6_addr *faddr, const __be16 fport);
354 
sk_daddr_set(struct sock * sk,__be32 addr)355 static inline void sk_daddr_set(struct sock *sk, __be32 addr)
356 {
357 	sk->sk_daddr = addr; /* alias of inet_daddr */
358 #if IS_ENABLED(CONFIG_IPV6)
359 	ipv6_addr_set_v4mapped(addr, &sk->sk_v6_daddr);
360 #endif
361 }
362 
sk_rcv_saddr_set(struct sock * sk,__be32 addr)363 static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr)
364 {
365 	sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */
366 #if IS_ENABLED(CONFIG_IPV6)
367 	ipv6_addr_set_v4mapped(addr, &sk->sk_v6_rcv_saddr);
368 #endif
369 }
370 
371 int __inet_hash_connect(struct inet_timewait_death_row *death_row,
372 			struct sock *sk, u64 port_offset,
373 			int (*check_established)(struct inet_timewait_death_row *,
374 						 struct sock *, __u16,
375 						 struct inet_timewait_sock **));
376 
377 int inet_hash_connect(struct inet_timewait_death_row *death_row,
378 		      struct sock *sk);
379 #endif /* _INET_HASHTABLES_H */
380