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/ip.h> 27 #include <net/sock.h> 28 #include <net/route.h> 29 #include <net/tcp_states.h> 30 #include <net/netns/hash.h> 31 32 #include <linux/refcount.h> 33 #include <asm/byteorder.h> 34 35 /* This is for all connections with a full identity, no wildcards. 36 * The 'e' prefix stands for Establish, but we really put all sockets 37 * but LISTEN ones. 38 */ 39 struct inet_ehash_bucket { 40 struct hlist_nulls_head chain; 41 }; 42 43 /* There are a few simple rules, which allow for local port reuse by 44 * an application. In essence: 45 * 46 * 1) Sockets bound to different interfaces may share a local port. 47 * Failing that, goto test 2. 48 * 2) If all sockets have sk->sk_reuse set, and none of them are in 49 * TCP_LISTEN state, the port may be shared. 50 * Failing that, goto test 3. 51 * 3) If all sockets are bound to a specific inet_sk(sk)->rcv_saddr local 52 * address, and none of them are the same, the port may be 53 * shared. 54 * Failing this, the port cannot be shared. 55 * 56 * The interesting point, is test #2. This is what an FTP server does 57 * all day. To optimize this case we use a specific flag bit defined 58 * below. As we add sockets to a bind bucket list, we perform a 59 * check of: (newsk->sk_reuse && (newsk->sk_state != TCP_LISTEN)) 60 * As long as all sockets added to a bind bucket pass this test, 61 * the flag bit will be set. 62 * The resulting situation is that tcp_v[46]_verify_bind() can just check 63 * for this flag bit, if it is set and the socket trying to bind has 64 * sk->sk_reuse set, we don't even have to walk the owners list at all, 65 * we return that it is ok to bind this socket to the requested local port. 66 * 67 * Sounds like a lot of work, but it is worth it. In a more naive 68 * implementation (ie. current FreeBSD etc.) the entire list of ports 69 * must be walked for each data port opened by an ftp server. Needless 70 * to say, this does not scale at all. With a couple thousand FTP 71 * users logged onto your box, isn't it nice to know that new data 72 * ports are created in O(1) time? I thought so. ;-) -DaveM 73 */ 74 #define FASTREUSEPORT_ANY 1 75 #define FASTREUSEPORT_STRICT 2 76 77 struct inet_bind_bucket { 78 possible_net_t ib_net; 79 int l3mdev; 80 unsigned short port; 81 signed char fastreuse; 82 signed char fastreuseport; 83 kuid_t fastuid; 84 #if IS_ENABLED(CONFIG_IPV6) 85 struct in6_addr fast_v6_rcv_saddr; 86 #endif 87 __be32 fast_rcv_saddr; 88 unsigned short fast_sk_family; 89 bool fast_ipv6_only; 90 struct hlist_node node; 91 struct hlist_head owners; 92 }; 93 94 struct inet_bind2_bucket { 95 possible_net_t ib_net; 96 int l3mdev; 97 unsigned short port; 98 #if IS_ENABLED(CONFIG_IPV6) 99 unsigned short family; 100 #endif 101 union { 102 #if IS_ENABLED(CONFIG_IPV6) 103 struct in6_addr v6_rcv_saddr; 104 #endif 105 __be32 rcv_saddr; 106 }; 107 /* Node in the bhash2 inet_bind_hashbucket chain */ 108 struct hlist_node node; 109 /* List of sockets hashed to this bucket */ 110 struct hlist_head owners; 111 }; 112 113 static inline struct net *ib_net(const struct inet_bind_bucket *ib) 114 { 115 return read_pnet(&ib->ib_net); 116 } 117 118 static inline struct net *ib2_net(const struct inet_bind2_bucket *ib) 119 { 120 return read_pnet(&ib->ib_net); 121 } 122 123 #define inet_bind_bucket_for_each(tb, head) \ 124 hlist_for_each_entry(tb, head, node) 125 126 struct inet_bind_hashbucket { 127 spinlock_t lock; 128 struct hlist_head chain; 129 }; 130 131 /* Sockets can be hashed in established or listening table. 132 * We must use different 'nulls' end-of-chain value for all hash buckets : 133 * A socket might transition from ESTABLISH to LISTEN state without 134 * RCU grace period. A lookup in ehash table needs to handle this case. 135 */ 136 #define LISTENING_NULLS_BASE (1U << 29) 137 struct inet_listen_hashbucket { 138 spinlock_t lock; 139 struct hlist_nulls_head nulls_head; 140 }; 141 142 /* This is for listening sockets, thus all sockets which possess wildcards. */ 143 #define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */ 144 145 struct inet_hashinfo { 146 /* This is for sockets with full identity only. Sockets here will 147 * always be without wildcards and will have the following invariant: 148 * 149 * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE 150 * 151 */ 152 struct inet_ehash_bucket *ehash; 153 spinlock_t *ehash_locks; 154 unsigned int ehash_mask; 155 unsigned int ehash_locks_mask; 156 157 /* Ok, let's try this, I give up, we do need a local binding 158 * TCP hash as well as the others for fast bind/connect. 159 */ 160 struct kmem_cache *bind_bucket_cachep; 161 /* This bind table is hashed by local port */ 162 struct inet_bind_hashbucket *bhash; 163 struct kmem_cache *bind2_bucket_cachep; 164 /* This bind table is hashed by local port and sk->sk_rcv_saddr (ipv4) 165 * or sk->sk_v6_rcv_saddr (ipv6). This 2nd bind table is used 166 * primarily for expediting bind conflict resolution. 167 */ 168 struct inet_bind_hashbucket *bhash2; 169 unsigned int bhash_size; 170 171 /* The 2nd listener table hashed by local port and address */ 172 unsigned int lhash2_mask; 173 struct inet_listen_hashbucket *lhash2; 174 175 bool pernet; 176 }; 177 178 static inline struct inet_hashinfo *tcp_or_dccp_get_hashinfo(const struct sock *sk) 179 { 180 #if IS_ENABLED(CONFIG_IP_DCCP) 181 return sk->sk_prot->h.hashinfo ? : 182 sock_net(sk)->ipv4.tcp_death_row.hashinfo; 183 #else 184 return sock_net(sk)->ipv4.tcp_death_row.hashinfo; 185 #endif 186 } 187 188 static inline struct inet_listen_hashbucket * 189 inet_lhash2_bucket(struct inet_hashinfo *h, u32 hash) 190 { 191 return &h->lhash2[hash & h->lhash2_mask]; 192 } 193 194 static inline struct inet_ehash_bucket *inet_ehash_bucket( 195 struct inet_hashinfo *hashinfo, 196 unsigned int hash) 197 { 198 return &hashinfo->ehash[hash & hashinfo->ehash_mask]; 199 } 200 201 static inline spinlock_t *inet_ehash_lockp( 202 struct inet_hashinfo *hashinfo, 203 unsigned int hash) 204 { 205 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask]; 206 } 207 208 int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo); 209 210 static inline void inet_hashinfo2_free_mod(struct inet_hashinfo *h) 211 { 212 kfree(h->lhash2); 213 h->lhash2 = NULL; 214 } 215 216 static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo) 217 { 218 kvfree(hashinfo->ehash_locks); 219 hashinfo->ehash_locks = NULL; 220 } 221 222 struct inet_hashinfo *inet_pernet_hashinfo_alloc(struct inet_hashinfo *hashinfo, 223 unsigned int ehash_entries); 224 void inet_pernet_hashinfo_free(struct inet_hashinfo *hashinfo); 225 226 struct inet_bind_bucket * 227 inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net, 228 struct inet_bind_hashbucket *head, 229 const unsigned short snum, int l3mdev); 230 void inet_bind_bucket_destroy(struct kmem_cache *cachep, 231 struct inet_bind_bucket *tb); 232 233 bool inet_bind_bucket_match(const struct inet_bind_bucket *tb, 234 const struct net *net, unsigned short port, 235 int l3mdev); 236 237 struct inet_bind2_bucket * 238 inet_bind2_bucket_create(struct kmem_cache *cachep, struct net *net, 239 struct inet_bind_hashbucket *head, 240 unsigned short port, int l3mdev, 241 const struct sock *sk); 242 243 void inet_bind2_bucket_destroy(struct kmem_cache *cachep, 244 struct inet_bind2_bucket *tb); 245 246 struct inet_bind2_bucket * 247 inet_bind2_bucket_find(const struct inet_bind_hashbucket *head, 248 const struct net *net, 249 unsigned short port, int l3mdev, 250 const struct sock *sk); 251 252 bool inet_bind2_bucket_match_addr_any(const struct inet_bind2_bucket *tb, 253 const struct net *net, unsigned short port, 254 int l3mdev, const struct sock *sk); 255 256 static inline u32 inet_bhashfn(const struct net *net, const __u16 lport, 257 const u32 bhash_size) 258 { 259 return (lport + net_hash_mix(net)) & (bhash_size - 1); 260 } 261 262 static inline struct inet_bind_hashbucket * 263 inet_bhashfn_portaddr(const struct inet_hashinfo *hinfo, const struct sock *sk, 264 const struct net *net, unsigned short port) 265 { 266 u32 hash; 267 268 #if IS_ENABLED(CONFIG_IPV6) 269 if (sk->sk_family == AF_INET6) 270 hash = ipv6_portaddr_hash(net, &sk->sk_v6_rcv_saddr, port); 271 else 272 #endif 273 hash = ipv4_portaddr_hash(net, sk->sk_rcv_saddr, port); 274 return &hinfo->bhash2[hash & (hinfo->bhash_size - 1)]; 275 } 276 277 struct inet_bind_hashbucket * 278 inet_bhash2_addr_any_hashbucket(const struct sock *sk, const struct net *net, int port); 279 280 /* This should be called whenever a socket's sk_rcv_saddr (ipv4) or 281 * sk_v6_rcv_saddr (ipv6) changes after it has been binded. The socket's 282 * rcv_saddr field should already have been updated when this is called. 283 */ 284 int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family); 285 void inet_bhash2_reset_saddr(struct sock *sk); 286 287 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, 288 struct inet_bind2_bucket *tb2, unsigned short port); 289 290 /* Caller must disable local BH processing. */ 291 int __inet_inherit_port(const struct sock *sk, struct sock *child); 292 293 void inet_put_port(struct sock *sk); 294 295 void inet_hashinfo2_init(struct inet_hashinfo *h, const char *name, 296 unsigned long numentries, int scale, 297 unsigned long low_limit, 298 unsigned long high_limit); 299 int inet_hashinfo2_init_mod(struct inet_hashinfo *h); 300 301 bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk); 302 bool inet_ehash_nolisten(struct sock *sk, struct sock *osk, 303 bool *found_dup_sk); 304 int __inet_hash(struct sock *sk, struct sock *osk); 305 int inet_hash(struct sock *sk); 306 void inet_unhash(struct sock *sk); 307 308 struct sock *__inet_lookup_listener(struct net *net, 309 struct inet_hashinfo *hashinfo, 310 struct sk_buff *skb, int doff, 311 const __be32 saddr, const __be16 sport, 312 const __be32 daddr, 313 const unsigned short hnum, 314 const int dif, const int sdif); 315 316 static inline struct sock *inet_lookup_listener(struct net *net, 317 struct inet_hashinfo *hashinfo, 318 struct sk_buff *skb, int doff, 319 __be32 saddr, __be16 sport, 320 __be32 daddr, __be16 dport, int dif, int sdif) 321 { 322 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, sport, 323 daddr, ntohs(dport), dif, sdif); 324 } 325 326 /* Socket demux engine toys. */ 327 /* What happens here is ugly; there's a pair of adjacent fields in 328 struct inet_sock; __be16 dport followed by __u16 num. We want to 329 search by pair, so we combine the keys into a single 32bit value 330 and compare with 32bit value read from &...->dport. Let's at least 331 make sure that it's not mixed with anything else... 332 On 64bit targets we combine comparisons with pair of adjacent __be32 333 fields in the same way. 334 */ 335 #ifdef __BIG_ENDIAN 336 #define INET_COMBINED_PORTS(__sport, __dport) \ 337 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport))) 338 #else /* __LITTLE_ENDIAN */ 339 #define INET_COMBINED_PORTS(__sport, __dport) \ 340 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport))) 341 #endif 342 343 #ifdef __BIG_ENDIAN 344 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 345 const __addrpair __name = (__force __addrpair) ( \ 346 (((__force __u64)(__be32)(__saddr)) << 32) | \ 347 ((__force __u64)(__be32)(__daddr))) 348 #else /* __LITTLE_ENDIAN */ 349 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 350 const __addrpair __name = (__force __addrpair) ( \ 351 (((__force __u64)(__be32)(__daddr)) << 32) | \ 352 ((__force __u64)(__be32)(__saddr))) 353 #endif /* __BIG_ENDIAN */ 354 355 static inline bool inet_match(struct net *net, const struct sock *sk, 356 const __addrpair cookie, const __portpair ports, 357 int dif, int sdif) 358 { 359 if (!net_eq(sock_net(sk), net) || 360 sk->sk_portpair != ports || 361 sk->sk_addrpair != cookie) 362 return false; 363 364 /* READ_ONCE() paired with WRITE_ONCE() in sock_bindtoindex_locked() */ 365 return inet_sk_bound_dev_eq(net, READ_ONCE(sk->sk_bound_dev_if), dif, 366 sdif); 367 } 368 369 /* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need 370 * not check it for lookups anymore, thanks Alexey. -DaveM 371 */ 372 struct sock *__inet_lookup_established(struct net *net, 373 struct inet_hashinfo *hashinfo, 374 const __be32 saddr, const __be16 sport, 375 const __be32 daddr, const u16 hnum, 376 const int dif, const int sdif); 377 378 static inline struct sock * 379 inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo, 380 const __be32 saddr, const __be16 sport, 381 const __be32 daddr, const __be16 dport, 382 const int dif) 383 { 384 return __inet_lookup_established(net, hashinfo, saddr, sport, daddr, 385 ntohs(dport), dif, 0); 386 } 387 388 static inline struct sock *__inet_lookup(struct net *net, 389 struct inet_hashinfo *hashinfo, 390 struct sk_buff *skb, int doff, 391 const __be32 saddr, const __be16 sport, 392 const __be32 daddr, const __be16 dport, 393 const int dif, const int sdif, 394 bool *refcounted) 395 { 396 u16 hnum = ntohs(dport); 397 struct sock *sk; 398 399 sk = __inet_lookup_established(net, hashinfo, saddr, sport, 400 daddr, hnum, dif, sdif); 401 *refcounted = true; 402 if (sk) 403 return sk; 404 *refcounted = false; 405 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, 406 sport, daddr, hnum, dif, sdif); 407 } 408 409 static inline struct sock *inet_lookup(struct net *net, 410 struct inet_hashinfo *hashinfo, 411 struct sk_buff *skb, int doff, 412 const __be32 saddr, const __be16 sport, 413 const __be32 daddr, const __be16 dport, 414 const int dif) 415 { 416 struct sock *sk; 417 bool refcounted; 418 419 sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr, 420 dport, dif, 0, &refcounted); 421 422 if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt)) 423 sk = NULL; 424 return sk; 425 } 426 427 static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo, 428 struct sk_buff *skb, 429 int doff, 430 const __be16 sport, 431 const __be16 dport, 432 const int sdif, 433 bool *refcounted) 434 { 435 struct sock *sk = skb_steal_sock(skb, refcounted); 436 const struct iphdr *iph = ip_hdr(skb); 437 438 if (sk) 439 return sk; 440 441 return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb, 442 doff, iph->saddr, sport, 443 iph->daddr, dport, inet_iif(skb), sdif, 444 refcounted); 445 } 446 447 u32 inet6_ehashfn(const struct net *net, 448 const struct in6_addr *laddr, const u16 lport, 449 const struct in6_addr *faddr, const __be16 fport); 450 451 static inline void sk_daddr_set(struct sock *sk, __be32 addr) 452 { 453 sk->sk_daddr = addr; /* alias of inet_daddr */ 454 #if IS_ENABLED(CONFIG_IPV6) 455 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_daddr); 456 #endif 457 } 458 459 static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr) 460 { 461 sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */ 462 #if IS_ENABLED(CONFIG_IPV6) 463 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_rcv_saddr); 464 #endif 465 } 466 467 int __inet_hash_connect(struct inet_timewait_death_row *death_row, 468 struct sock *sk, u64 port_offset, 469 int (*check_established)(struct inet_timewait_death_row *, 470 struct sock *, __u16, 471 struct inet_timewait_sock **)); 472 473 int inet_hash_connect(struct inet_timewait_death_row *death_row, 474 struct sock *sk); 475 #endif /* _INET_HASHTABLES_H */ 476