root/include/net/inet_hashtables.h

INCLUDED FROM

DEFINITIONS

1. ib_net
2. inet_lhash2_bucket
3. inet_ehash_lockp
4. inet_hashinfo2_free_mod
5. inet_ehash_locks_free
6. inet_sk_bound_dev_eq
7. inet_bhashfn
8. inet_lhashfn
9. inet_sk_listen_hashfn
10. inet_lookup_listener
11. inet_lookup_established
12. __inet_lookup
13. inet_lookup
14. __inet_lookup_skb
15. sk_daddr_set
16. sk_rcv_saddr_set

   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 
  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         unsigned int            count;
 115         union {
 116                 struct hlist_head       head;
 117                 struct hlist_nulls_head nulls_head;
 118         };
 119 };
 120 
 121 /* This is for listening sockets, thus all sockets which possess wildcards. */
 122 #define INET_LHTABLE_SIZE       32      /* Yes, really, this is all you need. */
 123 
 124 struct inet_hashinfo {
 125         /* This is for sockets with full identity only.  Sockets here will
 126          * always be without wildcards and will have the following invariant:
 127          *
 128          *          TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE
 129          *
 130          */
 131         struct inet_ehash_bucket        *ehash;
 132         spinlock_t                      *ehash_locks;
 133         unsigned int                    ehash_mask;
 134         unsigned int                    ehash_locks_mask;
 135 
 136         /* Ok, let's try this, I give up, we do need a local binding
 137          * TCP hash as well as the others for fast bind/connect.
 138          */
 139         struct kmem_cache               *bind_bucket_cachep;
 140         struct inet_bind_hashbucket     *bhash;
 141         unsigned int                    bhash_size;
 142 
 143         /* The 2nd listener table hashed by local port and address */
 144         unsigned int                    lhash2_mask;
 145         struct inet_listen_hashbucket   *lhash2;
 146 
 147         /* All the above members are written once at bootup and
 148          * never written again _or_ are predominantly read-access.
 149          *
 150          * Now align to a new cache line as all the following members
 151          * might be often dirty.
 152          */
 153         /* All sockets in TCP_LISTEN state will be in listening_hash.
 154          * This is the only table where wildcard'd TCP sockets can
 155          * exist.  listening_hash is only hashed by local port number.
 156          * If lhash2 is initialized, the same socket will also be hashed
 157          * to lhash2 by port and address.
 158          */
 159         struct inet_listen_hashbucket   listening_hash[INET_LHTABLE_SIZE]
 160                                         ____cacheline_aligned_in_smp;
 161 };
 162 
 163 #define inet_lhash2_for_each_icsk_rcu(__icsk, list) \
 164         hlist_for_each_entry_rcu(__icsk, list, icsk_listen_portaddr_node)
 165 
 166 static inline struct inet_listen_hashbucket *
 167 inet_lhash2_bucket(struct inet_hashinfo *h, u32 hash)
 168 {
 169         return &h->lhash2[hash & h->lhash2_mask];
 170 }
 171 
 172 static inline struct inet_ehash_bucket *inet_ehash_bucket(
 173         struct inet_hashinfo *hashinfo,
 174         unsigned int hash)
 175 {
 176         return &hashinfo->ehash[hash & hashinfo->ehash_mask];
 177 }
 178 
 179 static inline spinlock_t *inet_ehash_lockp(
 180         struct inet_hashinfo *hashinfo,
 181         unsigned int hash)
 182 {
 183         return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask];
 184 }
 185 
 186 int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo);
 187 
 188 static inline void inet_hashinfo2_free_mod(struct inet_hashinfo *h)
 189 {
 190         kfree(h->lhash2);
 191         h->lhash2 = NULL;
 192 }
 193 
 194 static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo)
 195 {
 196         kvfree(hashinfo->ehash_locks);
 197         hashinfo->ehash_locks = NULL;
 198 }
 199 
 200 static inline bool inet_sk_bound_dev_eq(struct net *net, int bound_dev_if,
 201                                         int dif, int sdif)
 202 {
 203 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
 204         return inet_bound_dev_eq(!!net->ipv4.sysctl_tcp_l3mdev_accept,
 205                                  bound_dev_if, dif, sdif);
 206 #else
 207         return inet_bound_dev_eq(true, bound_dev_if, dif, sdif);
 208 #endif
 209 }
 210 
 211 struct inet_bind_bucket *
 212 inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net,
 213                         struct inet_bind_hashbucket *head,
 214                         const unsigned short snum, int l3mdev);
 215 void inet_bind_bucket_destroy(struct kmem_cache *cachep,
 216                               struct inet_bind_bucket *tb);
 217 
 218 static inline u32 inet_bhashfn(const struct net *net, const __u16 lport,
 219                                const u32 bhash_size)
 220 {
 221         return (lport + net_hash_mix(net)) & (bhash_size - 1);
 222 }
 223 
 224 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
 225                     const unsigned short snum);
 226 
 227 /* These can have wildcards, don't try too hard. */
 228 static inline u32 inet_lhashfn(const struct net *net, const unsigned short num)
 229 {
 230         return (num + net_hash_mix(net)) & (INET_LHTABLE_SIZE - 1);
 231 }
 232 
 233 static inline int inet_sk_listen_hashfn(const struct sock *sk)
 234 {
 235         return inet_lhashfn(sock_net(sk), inet_sk(sk)->inet_num);
 236 }
 237 
 238 /* Caller must disable local BH processing. */
 239 int __inet_inherit_port(const struct sock *sk, struct sock *child);
 240 
 241 void inet_put_port(struct sock *sk);
 242 
 243 void inet_hashinfo_init(struct inet_hashinfo *h);
 244 void inet_hashinfo2_init(struct inet_hashinfo *h, const char *name,
 245                          unsigned long numentries, int scale,
 246                          unsigned long low_limit,
 247                          unsigned long high_limit);
 248 int inet_hashinfo2_init_mod(struct inet_hashinfo *h);
 249 
 250 bool inet_ehash_insert(struct sock *sk, struct sock *osk);
 251 bool inet_ehash_nolisten(struct sock *sk, struct sock *osk);
 252 int __inet_hash(struct sock *sk, struct sock *osk);
 253 int inet_hash(struct sock *sk);
 254 void inet_unhash(struct sock *sk);
 255 
 256 struct sock *__inet_lookup_listener(struct net *net,
 257                                     struct inet_hashinfo *hashinfo,
 258                                     struct sk_buff *skb, int doff,
 259                                     const __be32 saddr, const __be16 sport,
 260                                     const __be32 daddr,
 261                                     const unsigned short hnum,
 262                                     const int dif, const int sdif);
 263 
 264 static inline struct sock *inet_lookup_listener(struct net *net,
 265                 struct inet_hashinfo *hashinfo,
 266                 struct sk_buff *skb, int doff,
 267                 __be32 saddr, __be16 sport,
 268                 __be32 daddr, __be16 dport, int dif, int sdif)
 269 {
 270         return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, sport,
 271                                       daddr, ntohs(dport), dif, sdif);
 272 }
 273 
 274 /* Socket demux engine toys. */
 275 /* What happens here is ugly; there's a pair of adjacent fields in
 276    struct inet_sock; __be16 dport followed by __u16 num.  We want to
 277    search by pair, so we combine the keys into a single 32bit value
 278    and compare with 32bit value read from &...->dport.  Let's at least
 279    make sure that it's not mixed with anything else...
 280    On 64bit targets we combine comparisons with pair of adjacent __be32
 281    fields in the same way.
 282 */
 283 #ifdef __BIG_ENDIAN
 284 #define INET_COMBINED_PORTS(__sport, __dport) \
 285         ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport)))
 286 #else /* __LITTLE_ENDIAN */
 287 #define INET_COMBINED_PORTS(__sport, __dport) \
 288         ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport)))
 289 #endif
 290 
 291 #if (BITS_PER_LONG == 64)
 292 #ifdef __BIG_ENDIAN
 293 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
 294         const __addrpair __name = (__force __addrpair) ( \
 295                                    (((__force __u64)(__be32)(__saddr)) << 32) | \
 296                                    ((__force __u64)(__be32)(__daddr)))
 297 #else /* __LITTLE_ENDIAN */
 298 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
 299         const __addrpair __name = (__force __addrpair) ( \
 300                                    (((__force __u64)(__be32)(__daddr)) << 32) | \
 301                                    ((__force __u64)(__be32)(__saddr)))
 302 #endif /* __BIG_ENDIAN */
 303 #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif, __sdif) \
 304         (((__sk)->sk_portpair == (__ports))                     &&      \
 305          ((__sk)->sk_addrpair == (__cookie))                    &&      \
 306          (((__sk)->sk_bound_dev_if == (__dif))                  ||      \
 307           ((__sk)->sk_bound_dev_if == (__sdif)))                &&      \
 308          net_eq(sock_net(__sk), (__net)))
 309 #else /* 32-bit arch */
 310 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
 311         const int __name __deprecated __attribute__((unused))
 312 
 313 #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif, __sdif) \
 314         (((__sk)->sk_portpair == (__ports))             &&              \
 315          ((__sk)->sk_daddr      == (__saddr))           &&              \
 316          ((__sk)->sk_rcv_saddr  == (__daddr))           &&              \
 317          (((__sk)->sk_bound_dev_if == (__dif))          ||              \
 318           ((__sk)->sk_bound_dev_if == (__sdif)))        &&              \
 319          net_eq(sock_net(__sk), (__net)))
 320 #endif /* 64-bit arch */
 321 
 322 /* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need
 323  * not check it for lookups anymore, thanks Alexey. -DaveM
 324  */
 325 struct sock *__inet_lookup_established(struct net *net,
 326                                        struct inet_hashinfo *hashinfo,
 327                                        const __be32 saddr, const __be16 sport,
 328                                        const __be32 daddr, const u16 hnum,
 329                                        const int dif, const int sdif);
 330 
 331 static inline struct sock *
 332         inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo,
 333                                 const __be32 saddr, const __be16 sport,
 334                                 const __be32 daddr, const __be16 dport,
 335                                 const int dif)
 336 {
 337         return __inet_lookup_established(net, hashinfo, saddr, sport, daddr,
 338                                          ntohs(dport), dif, 0);
 339 }
 340 
 341 static inline struct sock *__inet_lookup(struct net *net,
 342                                          struct inet_hashinfo *hashinfo,
 343                                          struct sk_buff *skb, int doff,
 344                                          const __be32 saddr, const __be16 sport,
 345                                          const __be32 daddr, const __be16 dport,
 346                                          const int dif, const int sdif,
 347                                          bool *refcounted)
 348 {
 349         u16 hnum = ntohs(dport);
 350         struct sock *sk;
 351 
 352         sk = __inet_lookup_established(net, hashinfo, saddr, sport,
 353                                        daddr, hnum, dif, sdif);
 354         *refcounted = true;
 355         if (sk)
 356                 return sk;
 357         *refcounted = false;
 358         return __inet_lookup_listener(net, hashinfo, skb, doff, saddr,
 359                                       sport, daddr, hnum, dif, sdif);
 360 }
 361 
 362 static inline struct sock *inet_lookup(struct net *net,
 363                                        struct inet_hashinfo *hashinfo,
 364                                        struct sk_buff *skb, int doff,
 365                                        const __be32 saddr, const __be16 sport,
 366                                        const __be32 daddr, const __be16 dport,
 367                                        const int dif)
 368 {
 369         struct sock *sk;
 370         bool refcounted;
 371 
 372         sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,
 373                            dport, dif, 0, &refcounted);
 374 
 375         if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt))
 376                 sk = NULL;
 377         return sk;
 378 }
 379 
 380 static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo,
 381                                              struct sk_buff *skb,
 382                                              int doff,
 383                                              const __be16 sport,
 384                                              const __be16 dport,
 385                                              const int sdif,
 386                                              bool *refcounted)
 387 {
 388         struct sock *sk = skb_steal_sock(skb);
 389         const struct iphdr *iph = ip_hdr(skb);
 390 
 391         *refcounted = true;
 392         if (sk)
 393                 return sk;
 394 
 395         return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb,
 396                              doff, iph->saddr, sport,
 397                              iph->daddr, dport, inet_iif(skb), sdif,
 398                              refcounted);
 399 }
 400 
 401 u32 inet6_ehashfn(const struct net *net,
 402                   const struct in6_addr *laddr, const u16 lport,
 403                   const struct in6_addr *faddr, const __be16 fport);
 404 
 405 static inline void sk_daddr_set(struct sock *sk, __be32 addr)
 406 {
 407         sk->sk_daddr = addr; /* alias of inet_daddr */
 408 #if IS_ENABLED(CONFIG_IPV6)
 409         ipv6_addr_set_v4mapped(addr, &sk->sk_v6_daddr);
 410 #endif
 411 }
 412 
 413 static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr)
 414 {
 415         sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */
 416 #if IS_ENABLED(CONFIG_IPV6)
 417         ipv6_addr_set_v4mapped(addr, &sk->sk_v6_rcv_saddr);
 418 #endif
 419 }
 420 
 421 int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 422                         struct sock *sk, u32 port_offset,
 423                         int (*check_established)(struct inet_timewait_death_row *,
 424                                                  struct sock *, __u16,
 425                                                  struct inet_timewait_sock **));
 426 
 427 int inet_hash_connect(struct inet_timewait_death_row *death_row,
 428                       struct sock *sk);
 429 #endif /* _INET_HASHTABLES_H */