linux/include/net/inet_hashtables.h
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   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 */
  38struct 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
  76struct 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
  93static 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
 101struct 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)
 112struct 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
 124struct 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
 166static inline struct inet_listen_hashbucket *
 167inet_lhash2_bucket(struct inet_hashinfo *h, u32 hash)
 168{
 169        return &h->lhash2[hash & h->lhash2_mask];
 170}
 171
 172static 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
 179static 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
 186int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo);
 187
 188static inline void inet_hashinfo2_free_mod(struct inet_hashinfo *h)
 189{
 190        kfree(h->lhash2);
 191        h->lhash2 = NULL;
 192}
 193
 194static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo)
 195{
 196        kvfree(hashinfo->ehash_locks);
 197        hashinfo->ehash_locks = NULL;
 198}
 199
 200static 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
 211struct inet_bind_bucket *
 212inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net,
 213                        struct inet_bind_hashbucket *head,
 214                        const unsigned short snum, int l3mdev);
 215void inet_bind_bucket_destroy(struct kmem_cache *cachep,
 216                              struct inet_bind_bucket *tb);
 217
 218static 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
 224void 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. */
 228static 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
 233static 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. */
 239int __inet_inherit_port(const struct sock *sk, struct sock *child);
 240
 241void inet_put_port(struct sock *sk);
 242
 243void inet_hashinfo_init(struct inet_hashinfo *h);
 244void 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);
 248int inet_hashinfo2_init_mod(struct inet_hashinfo *h);
 249
 250bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk);
 251bool inet_ehash_nolisten(struct sock *sk, struct sock *osk,
 252                         bool *found_dup_sk);
 253int __inet_hash(struct sock *sk, struct sock *osk);
 254int inet_hash(struct sock *sk);
 255void inet_unhash(struct sock *sk);
 256
 257struct sock *__inet_lookup_listener(struct net *net,
 258                                    struct inet_hashinfo *hashinfo,
 259                                    struct sk_buff *skb, int doff,
 260                                    const __be32 saddr, const __be16 sport,
 261                                    const __be32 daddr,
 262                                    const unsigned short hnum,
 263                                    const int dif, const int sdif);
 264
 265static inline struct sock *inet_lookup_listener(struct net *net,
 266                struct inet_hashinfo *hashinfo,
 267                struct sk_buff *skb, int doff,
 268                __be32 saddr, __be16 sport,
 269                __be32 daddr, __be16 dport, int dif, int sdif)
 270{
 271        return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, sport,
 272                                      daddr, ntohs(dport), dif, sdif);
 273}
 274
 275/* Socket demux engine toys. */
 276/* What happens here is ugly; there's a pair of adjacent fields in
 277   struct inet_sock; __be16 dport followed by __u16 num.  We want to
 278   search by pair, so we combine the keys into a single 32bit value
 279   and compare with 32bit value read from &...->dport.  Let's at least
 280   make sure that it's not mixed with anything else...
 281   On 64bit targets we combine comparisons with pair of adjacent __be32
 282   fields in the same way.
 283*/
 284#ifdef __BIG_ENDIAN
 285#define INET_COMBINED_PORTS(__sport, __dport) \
 286        ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport)))
 287#else /* __LITTLE_ENDIAN */
 288#define INET_COMBINED_PORTS(__sport, __dport) \
 289        ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport)))
 290#endif
 291
 292#if (BITS_PER_LONG == 64)
 293#ifdef __BIG_ENDIAN
 294#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
 295        const __addrpair __name = (__force __addrpair) ( \
 296                                   (((__force __u64)(__be32)(__saddr)) << 32) | \
 297                                   ((__force __u64)(__be32)(__daddr)))
 298#else /* __LITTLE_ENDIAN */
 299#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
 300        const __addrpair __name = (__force __addrpair) ( \
 301                                   (((__force __u64)(__be32)(__daddr)) << 32) | \
 302                                   ((__force __u64)(__be32)(__saddr)))
 303#endif /* __BIG_ENDIAN */
 304#define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif, __sdif) \
 305        (((__sk)->sk_portpair == (__ports))                     &&      \
 306         ((__sk)->sk_addrpair == (__cookie))                    &&      \
 307         (((__sk)->sk_bound_dev_if == (__dif))                  ||      \
 308          ((__sk)->sk_bound_dev_if == (__sdif)))                &&      \
 309         net_eq(sock_net(__sk), (__net)))
 310#else /* 32-bit arch */
 311#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
 312        const int __name __deprecated __attribute__((unused))
 313
 314#define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif, __sdif) \
 315        (((__sk)->sk_portpair == (__ports))             &&              \
 316         ((__sk)->sk_daddr      == (__saddr))           &&              \
 317         ((__sk)->sk_rcv_saddr  == (__daddr))           &&              \
 318         (((__sk)->sk_bound_dev_if == (__dif))          ||              \
 319          ((__sk)->sk_bound_dev_if == (__sdif)))        &&              \
 320         net_eq(sock_net(__sk), (__net)))
 321#endif /* 64-bit arch */
 322
 323/* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need
 324 * not check it for lookups anymore, thanks Alexey. -DaveM
 325 */
 326struct sock *__inet_lookup_established(struct net *net,
 327                                       struct inet_hashinfo *hashinfo,
 328                                       const __be32 saddr, const __be16 sport,
 329                                       const __be32 daddr, const u16 hnum,
 330                                       const int dif, const int sdif);
 331
 332static inline struct sock *
 333        inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo,
 334                                const __be32 saddr, const __be16 sport,
 335                                const __be32 daddr, const __be16 dport,
 336                                const int dif)
 337{
 338        return __inet_lookup_established(net, hashinfo, saddr, sport, daddr,
 339                                         ntohs(dport), dif, 0);
 340}
 341
 342static inline struct sock *__inet_lookup(struct net *net,
 343                                         struct inet_hashinfo *hashinfo,
 344                                         struct sk_buff *skb, int doff,
 345                                         const __be32 saddr, const __be16 sport,
 346                                         const __be32 daddr, const __be16 dport,
 347                                         const int dif, const int sdif,
 348                                         bool *refcounted)
 349{
 350        u16 hnum = ntohs(dport);
 351        struct sock *sk;
 352
 353        sk = __inet_lookup_established(net, hashinfo, saddr, sport,
 354                                       daddr, hnum, dif, sdif);
 355        *refcounted = true;
 356        if (sk)
 357                return sk;
 358        *refcounted = false;
 359        return __inet_lookup_listener(net, hashinfo, skb, doff, saddr,
 360                                      sport, daddr, hnum, dif, sdif);
 361}
 362
 363static inline struct sock *inet_lookup(struct net *net,
 364                                       struct inet_hashinfo *hashinfo,
 365                                       struct sk_buff *skb, int doff,
 366                                       const __be32 saddr, const __be16 sport,
 367                                       const __be32 daddr, const __be16 dport,
 368                                       const int dif)
 369{
 370        struct sock *sk;
 371        bool refcounted;
 372
 373        sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,
 374                           dport, dif, 0, &refcounted);
 375
 376        if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt))
 377                sk = NULL;
 378        return sk;
 379}
 380
 381static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo,
 382                                             struct sk_buff *skb,
 383                                             int doff,
 384                                             const __be16 sport,
 385                                             const __be16 dport,
 386                                             const int sdif,
 387                                             bool *refcounted)
 388{
 389        struct sock *sk = skb_steal_sock(skb, refcounted);
 390        const struct iphdr *iph = ip_hdr(skb);
 391
 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
 401u32 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
 405static 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
 413static 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
 421int __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
 427int inet_hash_connect(struct inet_timewait_death_row *death_row,
 428                      struct sock *sk);
 429#endif /* _INET_HASHTABLES_H */
 430