ipv6/inet6_hashtables.c

   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  *              Generic INET6 transport hashtables
   8  *
   9  * Authors:     Lotsa people, from code originally in tcp, generalised here
  10  *              by Arnaldo Carvalho de Melo <acme@mandriva.com>
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/random.h>
  15
  16 #include <net/addrconf.h>
  17 #include <net/inet_connection_sock.h>
  18 #include <net/inet_hashtables.h>
  19 #include <net/inet6_hashtables.h>
  20 #include <net/secure_seq.h>
  21 #include <net/ip.h>
  22 #include <net/sock_reuseport.h>
  23
  24 u32 inet6_ehashfn(const struct net *net,
  25                   const struct in6_addr *laddr, const u16 lport,
  26                   const struct in6_addr *faddr, const __be16 fport)
  27 {
  28         static u32 inet6_ehash_secret __read_mostly;
  29         static u32 ipv6_hash_secret __read_mostly;
  30
  31         u32 lhash, fhash;
  32
  33         net_get_random_once(&inet6_ehash_secret, sizeof(inet6_ehash_secret));
  34         net_get_random_once(&ipv6_hash_secret, sizeof(ipv6_hash_secret));
  35
  36         lhash = (__force u32)laddr->s6_addr32[3];
  37         fhash = __ipv6_addr_jhash(faddr, ipv6_hash_secret);
  38
  39         return __inet6_ehashfn(lhash, lport, fhash, fport,
  40                                inet6_ehash_secret + net_hash_mix(net));
  41 }
  42
  43 /*
  44  * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so
  45  * we need not check it for TCP lookups anymore, thanks Alexey. -DaveM
  46  *
  47  * The sockhash lock must be held as a reader here.
  48  */
  49 struct sock *__inet6_lookup_established(struct net *net,
  50                                         struct inet_hashinfo *hashinfo,
  51                                            const struct in6_addr *saddr,
  52                                            const __be16 sport,
  53                                            const struct in6_addr *daddr,
  54                                            const u16 hnum,
  55                                            const int dif, const int sdif)
  56 {
  57         struct sock *sk;
  58         const struct hlist_nulls_node *node;
  59         const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
  60         /* Optimize here for direct hit, only listening connections can
  61          * have wildcards anyways.
  62          */
  63         unsigned int hash = inet6_ehashfn(net, daddr, hnum, saddr, sport);
  64         unsigned int slot = hash & hashinfo->ehash_mask;
  65         struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
  66
  67
  68 begin:
  69         sk_nulls_for_each_rcu(sk, node, &head->chain) {
  70                 if (sk->sk_hash != hash)
  71                         continue;
  72                 if (!inet6_match(net, sk, saddr, daddr, ports, dif, sdif))
  73                         continue;
  74                 if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))
  75                         goto out;
  76
  77                 if (unlikely(!inet6_match(net, sk, saddr, daddr, ports, dif, sdif))) {
  78                         sock_gen_put(sk);
  79                         goto begin;
  80                 }
  81                 goto found;
  82         }
  83         if (get_nulls_value(node) != slot)
  84                 goto begin;
  85 out:
  86         sk = NULL;
  87 found:
  88         return sk;
  89 }
  90 EXPORT_SYMBOL(__inet6_lookup_established);
  91
  92 static inline int compute_score(struct sock *sk, struct net *net,
  93                                 const unsigned short hnum,
  94                                 const struct in6_addr *daddr,
  95                                 const int dif, const int sdif)
  96 {
  97         int score = -1;
  98
  99         if (net_eq(sock_net(sk), net) && inet_sk(sk)->inet_num == hnum &&
 100             sk->sk_family == PF_INET6) {
 101                 if (!ipv6_addr_equal(&sk->sk_v6_rcv_saddr, daddr))
 102                         return -1;
 103
 104                 if (!inet_sk_bound_dev_eq(net, sk->sk_bound_dev_if, dif, sdif))
 105                         return -1;
 106
 107                 score =  sk->sk_bound_dev_if ? 2 : 1;
 108                 if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
 109                         score++;
 110         }
 111         return score;
 112 }
 113
 114 static inline struct sock *lookup_reuseport(struct net *net, struct sock *sk,
 115                                             struct sk_buff *skb, int doff,
 116                                             const struct in6_addr *saddr,
 117                                             __be16 sport,
 118                                             const struct in6_addr *daddr,
 119                                             unsigned short hnum)
 120 {
 121         struct sock *reuse_sk = NULL;
 122         u32 phash;
 123
 124         if (sk->sk_reuseport) {
 125                 phash = inet6_ehashfn(net, daddr, hnum, saddr, sport);
 126                 reuse_sk = reuseport_select_sock(sk, phash, skb, doff);
 127         }
 128         return reuse_sk;
 129 }
 130
 131 /* called with rcu_read_lock() */
 132 static struct sock *inet6_lhash2_lookup(struct net *net,
 133                 struct inet_listen_hashbucket *ilb2,
 134                 struct sk_buff *skb, int doff,
 135                 const struct in6_addr *saddr,
 136                 const __be16 sport, const struct in6_addr *daddr,
 137                 const unsigned short hnum, const int dif, const int sdif)
 138 {
 139         struct sock *sk, *result = NULL;
 140         struct hlist_nulls_node *node;
 141         int score, hiscore = 0;
 142
 143         sk_nulls_for_each_rcu(sk, node, &ilb2->nulls_head) {
 144                 score = compute_score(sk, net, hnum, daddr, dif, sdif);
 145                 if (score > hiscore) {
 146                         result = lookup_reuseport(net, sk, skb, doff,
 147                                                   saddr, sport, daddr, hnum);
 148                         if (result)
 149                                 return result;
 150
 151                         result = sk;
 152                         hiscore = score;
 153                 }
 154         }
 155
 156         return result;
 157 }
 158
 159 static inline struct sock *inet6_lookup_run_bpf(struct net *net,
 160                                                 struct inet_hashinfo *hashinfo,
 161                                                 struct sk_buff *skb, int doff,
 162                                                 const struct in6_addr *saddr,
 163                                                 const __be16 sport,
 164                                                 const struct in6_addr *daddr,
 165                                                 const u16 hnum, const int dif)
 166 {
 167         struct sock *sk, *reuse_sk;
 168         bool no_reuseport;
 169
 170         if (hashinfo != net->ipv4.tcp_death_row.hashinfo)
 171                 return NULL; /* only TCP is supported */
 172
 173         no_reuseport = bpf_sk_lookup_run_v6(net, IPPROTO_TCP, saddr, sport,
 174                                             daddr, hnum, dif, &sk);
 175         if (no_reuseport || IS_ERR_OR_NULL(sk))
 176                 return sk;
 177
 178         reuse_sk = lookup_reuseport(net, sk, skb, doff, saddr, sport, daddr, hnum);
 179         if (reuse_sk)
 180                 sk = reuse_sk;
 181         return sk;
 182 }
 183
 184 struct sock *inet6_lookup_listener(struct net *net,
 185                 struct inet_hashinfo *hashinfo,
 186                 struct sk_buff *skb, int doff,
 187                 const struct in6_addr *saddr,
 188                 const __be16 sport, const struct in6_addr *daddr,
 189                 const unsigned short hnum, const int dif, const int sdif)
 190 {
 191         struct inet_listen_hashbucket *ilb2;
 192         struct sock *result = NULL;
 193         unsigned int hash2;
 194
 195         /* Lookup redirect from BPF */
 196         if (static_branch_unlikely(&bpf_sk_lookup_enabled)) {
 197                 result = inet6_lookup_run_bpf(net, hashinfo, skb, doff,
 198                                               saddr, sport, daddr, hnum, dif);
 199                 if (result)
 200                         goto done;
 201         }
 202
 203         hash2 = ipv6_portaddr_hash(net, daddr, hnum);
 204         ilb2 = inet_lhash2_bucket(hashinfo, hash2);
 205
 206         result = inet6_lhash2_lookup(net, ilb2, skb, doff,
 207                                      saddr, sport, daddr, hnum,
 208                                      dif, sdif);
 209         if (result)
 210                 goto done;
 211
 212         /* Lookup lhash2 with in6addr_any */
 213         hash2 = ipv6_portaddr_hash(net, &in6addr_any, hnum);
 214         ilb2 = inet_lhash2_bucket(hashinfo, hash2);
 215
 216         result = inet6_lhash2_lookup(net, ilb2, skb, doff,
 217                                      saddr, sport, &in6addr_any, hnum,
 218                                      dif, sdif);
 219 done:
 220         if (IS_ERR(result))
 221                 return NULL;
 222         return result;
 223 }
 224 EXPORT_SYMBOL_GPL(inet6_lookup_listener);
 225
 226 struct sock *inet6_lookup(struct net *net, struct inet_hashinfo *hashinfo,
 227                           struct sk_buff *skb, int doff,
 228                           const struct in6_addr *saddr, const __be16 sport,
 229                           const struct in6_addr *daddr, const __be16 dport,
 230                           const int dif)
 231 {
 232         struct sock *sk;
 233         bool refcounted;
 234
 235         sk = __inet6_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,
 236                             ntohs(dport), dif, 0, &refcounted);
 237         if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt))
 238                 sk = NULL;
 239         return sk;
 240 }
 241 EXPORT_SYMBOL_GPL(inet6_lookup);
 242
 243 static int __inet6_check_established(struct inet_timewait_death_row *death_row,
 244                                      struct sock *sk, const __u16 lport,
 245                                      struct inet_timewait_sock **twp)
 246 {
 247         struct inet_hashinfo *hinfo = death_row->hashinfo;
 248         struct inet_sock *inet = inet_sk(sk);
 249         const struct in6_addr *daddr = &sk->sk_v6_rcv_saddr;
 250         const struct in6_addr *saddr = &sk->sk_v6_daddr;
 251         const int dif = sk->sk_bound_dev_if;
 252         struct net *net = sock_net(sk);
 253         const int sdif = l3mdev_master_ifindex_by_index(net, dif);
 254         const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
 255         const unsigned int hash = inet6_ehashfn(net, daddr, lport, saddr,
 256                                                 inet->inet_dport);
 257         struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
 258         spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
 259         struct sock *sk2;
 260         const struct hlist_nulls_node *node;
 261         struct inet_timewait_sock *tw = NULL;
 262
 263         spin_lock(lock);
 264
 265         sk_nulls_for_each(sk2, node, &head->chain) {
 266                 if (sk2->sk_hash != hash)
 267                         continue;
 268
 269                 if (likely(inet6_match(net, sk2, saddr, daddr, ports,
 270                                        dif, sdif))) {
 271                         if (sk2->sk_state == TCP_TIME_WAIT) {
 272                                 tw = inet_twsk(sk2);
 273                                 if (twsk_unique(sk, sk2, twp))
 274                                         break;
 275                         }
 276                         goto not_unique;
 277                 }
 278         }
 279
 280         /* Must record num and sport now. Otherwise we will see
 281          * in hash table socket with a funny identity.
 282          */
 283         inet->inet_num = lport;
 284         inet->inet_sport = htons(lport);
 285         sk->sk_hash = hash;
 286         WARN_ON(!sk_unhashed(sk));
 287         __sk_nulls_add_node_rcu(sk, &head->chain);
 288         if (tw) {
 289                 sk_nulls_del_node_init_rcu((struct sock *)tw);
 290                 __NET_INC_STATS(net, LINUX_MIB_TIMEWAITRECYCLED);
 291         }
 292         spin_unlock(lock);
 293         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 294
 295         if (twp) {
 296                 *twp = tw;
 297         } else if (tw) {
 298                 /* Silly. Should hash-dance instead... */
 299                 inet_twsk_deschedule_put(tw);
 300         }
 301         return 0;
 302
 303 not_unique:
 304         spin_unlock(lock);
 305         return -EADDRNOTAVAIL;
 306 }
 307
 308 static u64 inet6_sk_port_offset(const struct sock *sk)
 309 {
 310         const struct inet_sock *inet = inet_sk(sk);
 311
 312         return secure_ipv6_port_ephemeral(sk->sk_v6_rcv_saddr.s6_addr32,
 313                                           sk->sk_v6_daddr.s6_addr32,
 314                                           inet->inet_dport);
 315 }
 316
 317 int inet6_hash_connect(struct inet_timewait_death_row *death_row,
 318                        struct sock *sk)
 319 {
 320         u64 port_offset = 0;
 321
 322         if (!inet_sk(sk)->inet_num)
 323                 port_offset = inet6_sk_port_offset(sk);
 324         return __inet_hash_connect(death_row, sk, port_offset,
 325                                    __inet6_check_established);
 326 }
 327 EXPORT_SYMBOL_GPL(inet6_hash_connect);
 328
 329 int inet6_hash(struct sock *sk)
 330 {
 331         int err = 0;
 332
 333         if (sk->sk_state != TCP_CLOSE)
 334                 err = __inet_hash(sk, NULL);
 335
 336         return err;
 337 }
 338 EXPORT_SYMBOL_GPL(inet6_hash);