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 union { 99 #if IS_ENABLED(CONFIG_IPV6) 100 struct in6_addr v6_rcv_saddr; 101 #endif 102 __be32 rcv_saddr; 103 }; 104 /* Node in the bhash2 inet_bind_hashbucket chain */ 105 struct hlist_node node; 106 /* List of sockets hashed to this bucket */ 107 struct hlist_head owners; 108 }; 109 110 static inline struct net *ib_net(const struct inet_bind_bucket *ib) 111 { 112 return read_pnet(&ib->ib_net); 113 } 114 115 static inline struct net *ib2_net(const struct inet_bind2_bucket *ib) 116 { 117 return read_pnet(&ib->ib_net); 118 } 119 120 #define inet_bind_bucket_for_each(tb, head) \ 121 hlist_for_each_entry(tb, head, node) 122 123 struct inet_bind_hashbucket { 124 spinlock_t lock; 125 struct hlist_head chain; 126 }; 127 128 /* Sockets can be hashed in established or listening table. 129 * We must use different 'nulls' end-of-chain value for all hash buckets : 130 * A socket might transition from ESTABLISH to LISTEN state without 131 * RCU grace period. A lookup in ehash table needs to handle this case. 132 */ 133 #define LISTENING_NULLS_BASE (1U << 29) 134 struct inet_listen_hashbucket { 135 spinlock_t lock; 136 struct hlist_nulls_head nulls_head; 137 }; 138 139 /* This is for listening sockets, thus all sockets which possess wildcards. */ 140 #define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */ 141 142 struct inet_hashinfo { 143 /* This is for sockets with full identity only. Sockets here will 144 * always be without wildcards and will have the following invariant: 145 * 146 * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE 147 * 148 */ 149 struct inet_ehash_bucket *ehash; 150 spinlock_t *ehash_locks; 151 unsigned int ehash_mask; 152 unsigned int ehash_locks_mask; 153 154 /* Ok, let's try this, I give up, we do need a local binding 155 * TCP hash as well as the others for fast bind/connect. 156 */ 157 struct kmem_cache *bind_bucket_cachep; 158 /* This bind table is hashed by local port */ 159 struct inet_bind_hashbucket *bhash; 160 struct kmem_cache *bind2_bucket_cachep; 161 /* This bind table is hashed by local port and sk->sk_rcv_saddr (ipv4) 162 * or sk->sk_v6_rcv_saddr (ipv6). This 2nd bind table is used 163 * primarily for expediting bind conflict resolution. 164 */ 165 struct inet_bind_hashbucket *bhash2; 166 unsigned int bhash_size; 167 168 /* The 2nd listener table hashed by local port and address */ 169 unsigned int lhash2_mask; 170 struct inet_listen_hashbucket *lhash2; 171 172 bool pernet; 173 }; 174 175 static inline struct inet_hashinfo *tcp_or_dccp_get_hashinfo(const struct sock *sk) 176 { 177 #if IS_ENABLED(CONFIG_IP_DCCP) 178 return sk->sk_prot->h.hashinfo ? : 179 sock_net(sk)->ipv4.tcp_death_row.hashinfo; 180 #else 181 return sock_net(sk)->ipv4.tcp_death_row.hashinfo; 182 #endif 183 } 184 185 static inline struct inet_listen_hashbucket * 186 inet_lhash2_bucket(struct inet_hashinfo *h, u32 hash) 187 { 188 return &h->lhash2[hash & h->lhash2_mask]; 189 } 190 191 static inline struct inet_ehash_bucket *inet_ehash_bucket( 192 struct inet_hashinfo *hashinfo, 193 unsigned int hash) 194 { 195 return &hashinfo->ehash[hash & hashinfo->ehash_mask]; 196 } 197 198 static inline spinlock_t *inet_ehash_lockp( 199 struct inet_hashinfo *hashinfo, 200 unsigned int hash) 201 { 202 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask]; 203 } 204 205 int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo); 206 207 static inline void inet_hashinfo2_free_mod(struct inet_hashinfo *h) 208 { 209 kfree(h->lhash2); 210 h->lhash2 = NULL; 211 } 212 213 static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo) 214 { 215 kvfree(hashinfo->ehash_locks); 216 hashinfo->ehash_locks = NULL; 217 } 218 219 struct inet_hashinfo *inet_pernet_hashinfo_alloc(struct inet_hashinfo *hashinfo, 220 unsigned int ehash_entries); 221 void inet_pernet_hashinfo_free(struct inet_hashinfo *hashinfo); 222 223 struct inet_bind_bucket * 224 inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net, 225 struct inet_bind_hashbucket *head, 226 const unsigned short snum, int l3mdev); 227 void inet_bind_bucket_destroy(struct kmem_cache *cachep, 228 struct inet_bind_bucket *tb); 229 230 bool inet_bind_bucket_match(const struct inet_bind_bucket *tb, 231 const struct net *net, unsigned short port, 232 int l3mdev); 233 234 struct inet_bind2_bucket * 235 inet_bind2_bucket_create(struct kmem_cache *cachep, struct net *net, 236 struct inet_bind_hashbucket *head, 237 unsigned short port, int l3mdev, 238 const struct sock *sk); 239 240 void inet_bind2_bucket_destroy(struct kmem_cache *cachep, 241 struct inet_bind2_bucket *tb); 242 243 struct inet_bind2_bucket * 244 inet_bind2_bucket_find(const struct inet_bind_hashbucket *head, 245 const struct net *net, 246 unsigned short port, int l3mdev, 247 const struct sock *sk); 248 249 bool inet_bind2_bucket_match_addr_any(const struct inet_bind2_bucket *tb, 250 const struct net *net, unsigned short port, 251 int l3mdev, const struct sock *sk); 252 253 static inline u32 inet_bhashfn(const struct net *net, const __u16 lport, 254 const u32 bhash_size) 255 { 256 return (lport + net_hash_mix(net)) & (bhash_size - 1); 257 } 258 259 static inline struct inet_bind_hashbucket * 260 inet_bhashfn_portaddr(const struct inet_hashinfo *hinfo, const struct sock *sk, 261 const struct net *net, unsigned short port) 262 { 263 u32 hash; 264 265 #if IS_ENABLED(CONFIG_IPV6) 266 if (sk->sk_family == AF_INET6) 267 hash = ipv6_portaddr_hash(net, &sk->sk_v6_rcv_saddr, port); 268 else 269 #endif 270 hash = ipv4_portaddr_hash(net, sk->sk_rcv_saddr, port); 271 return &hinfo->bhash2[hash & (hinfo->bhash_size - 1)]; 272 } 273 274 struct inet_bind_hashbucket * 275 inet_bhash2_addr_any_hashbucket(const struct sock *sk, const struct net *net, int port); 276 277 /* This should be called whenever a socket's sk_rcv_saddr (ipv4) or 278 * sk_v6_rcv_saddr (ipv6) changes after it has been binded. The socket's 279 * rcv_saddr field should already have been updated when this is called. 280 */ 281 int inet_bhash2_update_saddr(struct inet_bind_hashbucket *prev_saddr, struct sock *sk); 282 283 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, 284 struct inet_bind2_bucket *tb2, unsigned short port); 285 286 /* Caller must disable local BH processing. */ 287 int __inet_inherit_port(const struct sock *sk, struct sock *child); 288 289 void inet_put_port(struct sock *sk); 290 291 void inet_hashinfo2_init(struct inet_hashinfo *h, const char *name, 292 unsigned long numentries, int scale, 293 unsigned long low_limit, 294 unsigned long high_limit); 295 int inet_hashinfo2_init_mod(struct inet_hashinfo *h); 296 297 bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk); 298 bool inet_ehash_nolisten(struct sock *sk, struct sock *osk, 299 bool *found_dup_sk); 300 int __inet_hash(struct sock *sk, struct sock *osk); 301 int inet_hash(struct sock *sk); 302 void inet_unhash(struct sock *sk); 303 304 struct sock *__inet_lookup_listener(struct net *net, 305 struct inet_hashinfo *hashinfo, 306 struct sk_buff *skb, int doff, 307 const __be32 saddr, const __be16 sport, 308 const __be32 daddr, 309 const unsigned short hnum, 310 const int dif, const int sdif); 311 312 static inline struct sock *inet_lookup_listener(struct net *net, 313 struct inet_hashinfo *hashinfo, 314 struct sk_buff *skb, int doff, 315 __be32 saddr, __be16 sport, 316 __be32 daddr, __be16 dport, int dif, int sdif) 317 { 318 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, sport, 319 daddr, ntohs(dport), dif, sdif); 320 } 321 322 /* Socket demux engine toys. */ 323 /* What happens here is ugly; there's a pair of adjacent fields in 324 struct inet_sock; __be16 dport followed by __u16 num. We want to 325 search by pair, so we combine the keys into a single 32bit value 326 and compare with 32bit value read from &...->dport. Let's at least 327 make sure that it's not mixed with anything else... 328 On 64bit targets we combine comparisons with pair of adjacent __be32 329 fields in the same way. 330 */ 331 #ifdef __BIG_ENDIAN 332 #define INET_COMBINED_PORTS(__sport, __dport) \ 333 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport))) 334 #else /* __LITTLE_ENDIAN */ 335 #define INET_COMBINED_PORTS(__sport, __dport) \ 336 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport))) 337 #endif 338 339 #ifdef __BIG_ENDIAN 340 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 341 const __addrpair __name = (__force __addrpair) ( \ 342 (((__force __u64)(__be32)(__saddr)) << 32) | \ 343 ((__force __u64)(__be32)(__daddr))) 344 #else /* __LITTLE_ENDIAN */ 345 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 346 const __addrpair __name = (__force __addrpair) ( \ 347 (((__force __u64)(__be32)(__daddr)) << 32) | \ 348 ((__force __u64)(__be32)(__saddr))) 349 #endif /* __BIG_ENDIAN */ 350 351 static inline bool inet_match(struct net *net, const struct sock *sk, 352 const __addrpair cookie, const __portpair ports, 353 int dif, int sdif) 354 { 355 if (!net_eq(sock_net(sk), net) || 356 sk->sk_portpair != ports || 357 sk->sk_addrpair != cookie) 358 return false; 359 360 /* READ_ONCE() paired with WRITE_ONCE() in sock_bindtoindex_locked() */ 361 return inet_sk_bound_dev_eq(net, READ_ONCE(sk->sk_bound_dev_if), dif, 362 sdif); 363 } 364 365 /* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need 366 * not check it for lookups anymore, thanks Alexey. -DaveM 367 */ 368 struct sock *__inet_lookup_established(struct net *net, 369 struct inet_hashinfo *hashinfo, 370 const __be32 saddr, const __be16 sport, 371 const __be32 daddr, const u16 hnum, 372 const int dif, const int sdif); 373 374 static inline struct sock * 375 inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo, 376 const __be32 saddr, const __be16 sport, 377 const __be32 daddr, const __be16 dport, 378 const int dif) 379 { 380 return __inet_lookup_established(net, hashinfo, saddr, sport, daddr, 381 ntohs(dport), dif, 0); 382 } 383 384 static inline struct sock *__inet_lookup(struct net *net, 385 struct inet_hashinfo *hashinfo, 386 struct sk_buff *skb, int doff, 387 const __be32 saddr, const __be16 sport, 388 const __be32 daddr, const __be16 dport, 389 const int dif, const int sdif, 390 bool *refcounted) 391 { 392 u16 hnum = ntohs(dport); 393 struct sock *sk; 394 395 sk = __inet_lookup_established(net, hashinfo, saddr, sport, 396 daddr, hnum, dif, sdif); 397 *refcounted = true; 398 if (sk) 399 return sk; 400 *refcounted = false; 401 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, 402 sport, daddr, hnum, dif, sdif); 403 } 404 405 static inline struct sock *inet_lookup(struct net *net, 406 struct inet_hashinfo *hashinfo, 407 struct sk_buff *skb, int doff, 408 const __be32 saddr, const __be16 sport, 409 const __be32 daddr, const __be16 dport, 410 const int dif) 411 { 412 struct sock *sk; 413 bool refcounted; 414 415 sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr, 416 dport, dif, 0, &refcounted); 417 418 if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt)) 419 sk = NULL; 420 return sk; 421 } 422 423 static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo, 424 struct sk_buff *skb, 425 int doff, 426 const __be16 sport, 427 const __be16 dport, 428 const int sdif, 429 bool *refcounted) 430 { 431 struct sock *sk = skb_steal_sock(skb, refcounted); 432 const struct iphdr *iph = ip_hdr(skb); 433 434 if (sk) 435 return sk; 436 437 return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb, 438 doff, iph->saddr, sport, 439 iph->daddr, dport, inet_iif(skb), sdif, 440 refcounted); 441 } 442 443 u32 inet6_ehashfn(const struct net *net, 444 const struct in6_addr *laddr, const u16 lport, 445 const struct in6_addr *faddr, const __be16 fport); 446 447 static inline void sk_daddr_set(struct sock *sk, __be32 addr) 448 { 449 sk->sk_daddr = addr; /* alias of inet_daddr */ 450 #if IS_ENABLED(CONFIG_IPV6) 451 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_daddr); 452 #endif 453 } 454 455 static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr) 456 { 457 sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */ 458 #if IS_ENABLED(CONFIG_IPV6) 459 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_rcv_saddr); 460 #endif 461 } 462 463 int __inet_hash_connect(struct inet_timewait_death_row *death_row, 464 struct sock *sk, u64 port_offset, 465 int (*check_established)(struct inet_timewait_death_row *, 466 struct sock *, __u16, 467 struct inet_timewait_sock **)); 468 469 int inet_hash_connect(struct inet_timewait_death_row *death_row, 470 struct sock *sk); 471 #endif /* _INET_HASHTABLES_H */ 472