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Linux/include/net/inet_hashtables.h

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  1 /*
  2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
  3  *              operating system.  INET is implemented using the BSD Socket
  4  *              interface as the means of communication with the user level.
  5  *
  6  * Authors:     Lotsa people, from code originally in tcp
  7  *
  8  *      This program is free software; you can redistribute it and/or
  9  *      modify it under the terms of the GNU General Public License
 10  *      as published by the Free Software Foundation; either version
 11  *      2 of the License, or (at your option) any later version.
 12  */
 13 
 14 #ifndef _INET_HASHTABLES_H
 15 #define _INET_HASHTABLES_H
 16 
 17 
 18 #include <linux/interrupt.h>
 19 #include <linux/ip.h>
 20 #include <linux/ipv6.h>
 21 #include <linux/list.h>
 22 #include <linux/slab.h>
 23 #include <linux/socket.h>
 24 #include <linux/spinlock.h>
 25 #include <linux/types.h>
 26 #include <linux/wait.h>
 27 
 28 #include <net/inet_connection_sock.h>
 29 #include <net/inet_sock.h>
 30 #include <net/sock.h>
 31 #include <net/route.h>
 32 #include <net/tcp_states.h>
 33 #include <net/netns/hash.h>
 34 
 35 #include <linux/atomic.h>
 36 #include <asm/byteorder.h>
 37 
 38 /* This is for all connections with a full identity, no wildcards.
 39  * The 'e' prefix stands for Establish, but we really put all sockets
 40  * but LISTEN ones.
 41  */
 42 struct inet_ehash_bucket {
 43         struct hlist_nulls_head chain;
 44 };
 45 
 46 /* There are a few simple rules, which allow for local port reuse by
 47  * an application.  In essence:
 48  *
 49  *      1) Sockets bound to different interfaces may share a local port.
 50  *         Failing that, goto test 2.
 51  *      2) If all sockets have sk->sk_reuse set, and none of them are in
 52  *         TCP_LISTEN state, the port may be shared.
 53  *         Failing that, goto test 3.
 54  *      3) If all sockets are bound to a specific inet_sk(sk)->rcv_saddr local
 55  *         address, and none of them are the same, the port may be
 56  *         shared.
 57  *         Failing this, the port cannot be shared.
 58  *
 59  * The interesting point, is test #2.  This is what an FTP server does
 60  * all day.  To optimize this case we use a specific flag bit defined
 61  * below.  As we add sockets to a bind bucket list, we perform a
 62  * check of: (newsk->sk_reuse && (newsk->sk_state != TCP_LISTEN))
 63  * As long as all sockets added to a bind bucket pass this test,
 64  * the flag bit will be set.
 65  * The resulting situation is that tcp_v[46]_verify_bind() can just check
 66  * for this flag bit, if it is set and the socket trying to bind has
 67  * sk->sk_reuse set, we don't even have to walk the owners list at all,
 68  * we return that it is ok to bind this socket to the requested local port.
 69  *
 70  * Sounds like a lot of work, but it is worth it.  In a more naive
 71  * implementation (ie. current FreeBSD etc.) the entire list of ports
 72  * must be walked for each data port opened by an ftp server.  Needless
 73  * to say, this does not scale at all.  With a couple thousand FTP
 74  * users logged onto your box, isn't it nice to know that new data
 75  * ports are created in O(1) time?  I thought so. ;-)   -DaveM
 76  */
 77 #define FASTREUSEPORT_ANY       1
 78 #define FASTREUSEPORT_STRICT    2
 79 
 80 struct inet_bind_bucket {
 81         possible_net_t          ib_net;
 82         unsigned short          port;
 83         signed char             fastreuse;
 84         signed char             fastreuseport;
 85         kuid_t                  fastuid;
 86 #if IS_ENABLED(CONFIG_IPV6)
 87         struct in6_addr         fast_v6_rcv_saddr;
 88 #endif
 89         __be32                  fast_rcv_saddr;
 90         unsigned short          fast_sk_family;
 91         bool                    fast_ipv6_only;
 92         struct hlist_node       node;
 93         struct hlist_head       owners;
 94 };
 95 
 96 static inline struct net *ib_net(struct inet_bind_bucket *ib)
 97 {
 98         return read_pnet(&ib->ib_net);
 99 }
100 
101 #define inet_bind_bucket_for_each(tb, head) \
102         hlist_for_each_entry(tb, head, node)
103 
104 struct inet_bind_hashbucket {
105         spinlock_t              lock;
106         struct hlist_head       chain;
107 };
108 
109 /*
110  * Sockets can be hashed in established or listening table
111  */
112 struct inet_listen_hashbucket {
113         spinlock_t              lock;
114         struct hlist_head       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 inet_bind_hashbucket     *bhash;
136 
137         unsigned int                    bhash_size;
138         /* 4 bytes hole on 64 bit */
139 
140         struct kmem_cache               *bind_bucket_cachep;
141 
142         /* All the above members are written once at bootup and
143          * never written again _or_ are predominantly read-access.
144          *
145          * Now align to a new cache line as all the following members
146          * might be often dirty.
147          */
148         /* All sockets in TCP_LISTEN state will be in here.  This is the only
149          * table where wildcard'd TCP sockets can exist.  Hash function here
150          * is just local port number.
151          */
152         struct inet_listen_hashbucket   listening_hash[INET_LHTABLE_SIZE]
153                                         ____cacheline_aligned_in_smp;
154 };
155 
156 static inline struct inet_ehash_bucket *inet_ehash_bucket(
157         struct inet_hashinfo *hashinfo,
158         unsigned int hash)
159 {
160         return &hashinfo->ehash[hash & hashinfo->ehash_mask];
161 }
162 
163 static inline spinlock_t *inet_ehash_lockp(
164         struct inet_hashinfo *hashinfo,
165         unsigned int hash)
166 {
167         return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask];
168 }
169 
170 int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo);
171 
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);
182 void inet_bind_bucket_destroy(struct kmem_cache *cachep,
183                               struct inet_bind_bucket *tb);
184 
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 /* These can have wildcards, don't try too hard. */
195 static inline u32 inet_lhashfn(const struct net *net, const unsigned short num)
196 {
197         return (num + net_hash_mix(net)) & (INET_LHTABLE_SIZE - 1);
198 }
199 
200 static inline int inet_sk_listen_hashfn(const struct sock *sk)
201 {
202         return inet_lhashfn(sock_net(sk), inet_sk(sk)->inet_num);
203 }
204 
205 /* Caller must disable local BH processing. */
206 int __inet_inherit_port(const struct sock *sk, struct sock *child);
207 
208 void inet_put_port(struct sock *sk);
209 
210 void inet_hashinfo_init(struct inet_hashinfo *h);
211 
212 bool inet_ehash_insert(struct sock *sk, struct sock *osk);
213 bool inet_ehash_nolisten(struct sock *sk, struct sock *osk);
214 int __inet_hash(struct sock *sk, struct sock *osk);
215 int inet_hash(struct sock *sk);
216 void inet_unhash(struct sock *sk);
217 
218 struct sock *__inet_lookup_listener(struct net *net,
219                                     struct inet_hashinfo *hashinfo,
220                                     struct sk_buff *skb, int doff,
221                                     const __be32 saddr, const __be16 sport,
222                                     const __be32 daddr,
223                                     const unsigned short hnum,
224                                     const int dif);
225 
226 static inline struct sock *inet_lookup_listener(struct net *net,
227                 struct inet_hashinfo *hashinfo,
228                 struct sk_buff *skb, int doff,
229                 __be32 saddr, __be16 sport,
230                 __be32 daddr, __be16 dport, int dif)
231 {
232         return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, sport,
233                                       daddr, ntohs(dport), dif);
234 }
235 
236 /* Socket demux engine toys. */
237 /* What happens here is ugly; there's a pair of adjacent fields in
238    struct inet_sock; __be16 dport followed by __u16 num.  We want to
239    search by pair, so we combine the keys into a single 32bit value
240    and compare with 32bit value read from &...->dport.  Let's at least
241    make sure that it's not mixed with anything else...
242    On 64bit targets we combine comparisons with pair of adjacent __be32
243    fields in the same way.
244 */
245 #ifdef __BIG_ENDIAN
246 #define INET_COMBINED_PORTS(__sport, __dport) \
247         ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport)))
248 #else /* __LITTLE_ENDIAN */
249 #define INET_COMBINED_PORTS(__sport, __dport) \
250         ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport)))
251 #endif
252 
253 #if (BITS_PER_LONG == 64)
254 #ifdef __BIG_ENDIAN
255 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
256         const __addrpair __name = (__force __addrpair) ( \
257                                    (((__force __u64)(__be32)(__saddr)) << 32) | \
258                                    ((__force __u64)(__be32)(__daddr)))
259 #else /* __LITTLE_ENDIAN */
260 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
261         const __addrpair __name = (__force __addrpair) ( \
262                                    (((__force __u64)(__be32)(__daddr)) << 32) | \
263                                    ((__force __u64)(__be32)(__saddr)))
264 #endif /* __BIG_ENDIAN */
265 #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif)     \
266         (((__sk)->sk_portpair == (__ports))                     &&      \
267          ((__sk)->sk_addrpair == (__cookie))                    &&      \
268          (!(__sk)->sk_bound_dev_if      ||                              \
269            ((__sk)->sk_bound_dev_if == (__dif)))                &&      \
270          net_eq(sock_net(__sk), (__net)))
271 #else /* 32-bit arch */
272 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
273         const int __name __deprecated __attribute__((unused))
274 
275 #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif) \
276         (((__sk)->sk_portpair == (__ports))             &&              \
277          ((__sk)->sk_daddr      == (__saddr))           &&              \
278          ((__sk)->sk_rcv_saddr  == (__daddr))           &&              \
279          (!(__sk)->sk_bound_dev_if      ||                              \
280            ((__sk)->sk_bound_dev_if == (__dif)))        &&              \
281          net_eq(sock_net(__sk), (__net)))
282 #endif /* 64-bit arch */
283 
284 /* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need
285  * not check it for lookups anymore, thanks Alexey. -DaveM
286  */
287 struct sock *__inet_lookup_established(struct net *net,
288                                        struct inet_hashinfo *hashinfo,
289                                        const __be32 saddr, const __be16 sport,
290                                        const __be32 daddr, const u16 hnum,
291                                        const int dif);
292 
293 static inline struct sock *
294         inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo,
295                                 const __be32 saddr, const __be16 sport,
296                                 const __be32 daddr, const __be16 dport,
297                                 const int dif)
298 {
299         return __inet_lookup_established(net, hashinfo, saddr, sport, daddr,
300                                          ntohs(dport), dif);
301 }
302 
303 static inline struct sock *__inet_lookup(struct net *net,
304                                          struct inet_hashinfo *hashinfo,
305                                          struct sk_buff *skb, int doff,
306                                          const __be32 saddr, const __be16 sport,
307                                          const __be32 daddr, const __be16 dport,
308                                          const int dif,
309                                          bool *refcounted)
310 {
311         u16 hnum = ntohs(dport);
312         struct sock *sk;
313 
314         sk = __inet_lookup_established(net, hashinfo, saddr, sport,
315                                        daddr, hnum, dif);
316         *refcounted = true;
317         if (sk)
318                 return sk;
319         *refcounted = false;
320         return __inet_lookup_listener(net, hashinfo, skb, doff, saddr,
321                                       sport, daddr, hnum, dif);
322 }
323 
324 static inline struct sock *inet_lookup(struct net *net,
325                                        struct inet_hashinfo *hashinfo,
326                                        struct sk_buff *skb, int doff,
327                                        const __be32 saddr, const __be16 sport,
328                                        const __be32 daddr, const __be16 dport,
329                                        const int dif)
330 {
331         struct sock *sk;
332         bool refcounted;
333 
334         sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,
335                            dport, dif, &refcounted);
336 
337         if (sk && !refcounted && !atomic_inc_not_zero(&sk->sk_refcnt))
338                 sk = NULL;
339         return sk;
340 }
341 
342 static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo,
343                                              struct sk_buff *skb,
344                                              int doff,
345                                              const __be16 sport,
346                                              const __be16 dport,
347                                              bool *refcounted)
348 {
349         struct sock *sk = skb_steal_sock(skb);
350         const struct iphdr *iph = ip_hdr(skb);
351 
352         *refcounted = true;
353         if (sk)
354                 return sk;
355 
356         return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb,
357                              doff, iph->saddr, sport,
358                              iph->daddr, dport, inet_iif(skb),
359                              refcounted);
360 }
361 
362 u32 sk_ehashfn(const struct sock *sk);
363 u32 inet6_ehashfn(const struct net *net,
364                   const struct in6_addr *laddr, const u16 lport,
365                   const struct in6_addr *faddr, const __be16 fport);
366 
367 static inline void sk_daddr_set(struct sock *sk, __be32 addr)
368 {
369         sk->sk_daddr = addr; /* alias of inet_daddr */
370 #if IS_ENABLED(CONFIG_IPV6)
371         ipv6_addr_set_v4mapped(addr, &sk->sk_v6_daddr);
372 #endif
373 }
374 
375 static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr)
376 {
377         sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */
378 #if IS_ENABLED(CONFIG_IPV6)
379         ipv6_addr_set_v4mapped(addr, &sk->sk_v6_rcv_saddr);
380 #endif
381 }
382 
383 int __inet_hash_connect(struct inet_timewait_death_row *death_row,
384                         struct sock *sk, u32 port_offset,
385                         int (*check_established)(struct inet_timewait_death_row *,
386                                                  struct sock *, __u16,
387                                                  struct inet_timewait_sock **));
388 
389 int inet_hash_connect(struct inet_timewait_death_row *death_row,
390                       struct sock *sk);
391 #endif /* _INET_HASHTABLES_H */
392 

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