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 }; 172 173 static inline struct inet_hashinfo *tcp_or_dccp_get_hashinfo(const struct sock *sk) 174 { 175 #if IS_ENABLED(CONFIG_IP_DCCP) 176 return sk->sk_prot->h.hashinfo ? : 177 sock_net(sk)->ipv4.tcp_death_row.hashinfo; 178 #else 179 return sock_net(sk)->ipv4.tcp_death_row.hashinfo; 180 #endif 181 } 182 183 static inline struct inet_listen_hashbucket * 184 inet_lhash2_bucket(struct inet_hashinfo *h, u32 hash) 185 { 186 return &h->lhash2[hash & h->lhash2_mask]; 187 } 188 189 static inline struct inet_ehash_bucket *inet_ehash_bucket( 190 struct inet_hashinfo *hashinfo, 191 unsigned int hash) 192 { 193 return &hashinfo->ehash[hash & hashinfo->ehash_mask]; 194 } 195 196 static inline spinlock_t *inet_ehash_lockp( 197 struct inet_hashinfo *hashinfo, 198 unsigned int hash) 199 { 200 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask]; 201 } 202 203 int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo); 204 205 static inline void inet_hashinfo2_free_mod(struct inet_hashinfo *h) 206 { 207 kfree(h->lhash2); 208 h->lhash2 = NULL; 209 } 210 211 static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo) 212 { 213 kvfree(hashinfo->ehash_locks); 214 hashinfo->ehash_locks = NULL; 215 } 216 217 struct inet_bind_bucket * 218 inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net, 219 struct inet_bind_hashbucket *head, 220 const unsigned short snum, int l3mdev); 221 void inet_bind_bucket_destroy(struct kmem_cache *cachep, 222 struct inet_bind_bucket *tb); 223 224 bool inet_bind_bucket_match(const struct inet_bind_bucket *tb, 225 const struct net *net, unsigned short port, 226 int l3mdev); 227 228 struct inet_bind2_bucket * 229 inet_bind2_bucket_create(struct kmem_cache *cachep, struct net *net, 230 struct inet_bind_hashbucket *head, 231 unsigned short port, int l3mdev, 232 const struct sock *sk); 233 234 void inet_bind2_bucket_destroy(struct kmem_cache *cachep, 235 struct inet_bind2_bucket *tb); 236 237 struct inet_bind2_bucket * 238 inet_bind2_bucket_find(const struct inet_bind_hashbucket *head, 239 const struct net *net, 240 unsigned short port, int l3mdev, 241 const struct sock *sk); 242 243 bool inet_bind2_bucket_match_addr_any(const struct inet_bind2_bucket *tb, 244 const struct net *net, unsigned short port, 245 int l3mdev, const struct sock *sk); 246 247 static inline u32 inet_bhashfn(const struct net *net, const __u16 lport, 248 const u32 bhash_size) 249 { 250 return (lport + net_hash_mix(net)) & (bhash_size - 1); 251 } 252 253 static inline struct inet_bind_hashbucket * 254 inet_bhashfn_portaddr(const struct inet_hashinfo *hinfo, const struct sock *sk, 255 const struct net *net, unsigned short port) 256 { 257 u32 hash; 258 259 #if IS_ENABLED(CONFIG_IPV6) 260 if (sk->sk_family == AF_INET6) 261 hash = ipv6_portaddr_hash(net, &sk->sk_v6_rcv_saddr, port); 262 else 263 #endif 264 hash = ipv4_portaddr_hash(net, sk->sk_rcv_saddr, port); 265 return &hinfo->bhash2[hash & (hinfo->bhash_size - 1)]; 266 } 267 268 struct inet_bind_hashbucket * 269 inet_bhash2_addr_any_hashbucket(const struct sock *sk, const struct net *net, int port); 270 271 /* This should be called whenever a socket's sk_rcv_saddr (ipv4) or 272 * sk_v6_rcv_saddr (ipv6) changes after it has been binded. The socket's 273 * rcv_saddr field should already have been updated when this is called. 274 */ 275 int inet_bhash2_update_saddr(struct inet_bind_hashbucket *prev_saddr, struct sock *sk); 276 277 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, 278 struct inet_bind2_bucket *tb2, unsigned short port); 279 280 /* Caller must disable local BH processing. */ 281 int __inet_inherit_port(const struct sock *sk, struct sock *child); 282 283 void inet_put_port(struct sock *sk); 284 285 void inet_hashinfo2_init(struct inet_hashinfo *h, const char *name, 286 unsigned long numentries, int scale, 287 unsigned long low_limit, 288 unsigned long high_limit); 289 int inet_hashinfo2_init_mod(struct inet_hashinfo *h); 290 291 bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk); 292 bool inet_ehash_nolisten(struct sock *sk, struct sock *osk, 293 bool *found_dup_sk); 294 int __inet_hash(struct sock *sk, struct sock *osk); 295 int inet_hash(struct sock *sk); 296 void inet_unhash(struct sock *sk); 297 298 struct sock *__inet_lookup_listener(struct net *net, 299 struct inet_hashinfo *hashinfo, 300 struct sk_buff *skb, int doff, 301 const __be32 saddr, const __be16 sport, 302 const __be32 daddr, 303 const unsigned short hnum, 304 const int dif, const int sdif); 305 306 static inline struct sock *inet_lookup_listener(struct net *net, 307 struct inet_hashinfo *hashinfo, 308 struct sk_buff *skb, int doff, 309 __be32 saddr, __be16 sport, 310 __be32 daddr, __be16 dport, int dif, int sdif) 311 { 312 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, sport, 313 daddr, ntohs(dport), dif, sdif); 314 } 315 316 /* Socket demux engine toys. */ 317 /* What happens here is ugly; there's a pair of adjacent fields in 318 struct inet_sock; __be16 dport followed by __u16 num. We want to 319 search by pair, so we combine the keys into a single 32bit value 320 and compare with 32bit value read from &...->dport. Let's at least 321 make sure that it's not mixed with anything else... 322 On 64bit targets we combine comparisons with pair of adjacent __be32 323 fields in the same way. 324 */ 325 #ifdef __BIG_ENDIAN 326 #define INET_COMBINED_PORTS(__sport, __dport) \ 327 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport))) 328 #else /* __LITTLE_ENDIAN */ 329 #define INET_COMBINED_PORTS(__sport, __dport) \ 330 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport))) 331 #endif 332 333 #ifdef __BIG_ENDIAN 334 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 335 const __addrpair __name = (__force __addrpair) ( \ 336 (((__force __u64)(__be32)(__saddr)) << 32) | \ 337 ((__force __u64)(__be32)(__daddr))) 338 #else /* __LITTLE_ENDIAN */ 339 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 340 const __addrpair __name = (__force __addrpair) ( \ 341 (((__force __u64)(__be32)(__daddr)) << 32) | \ 342 ((__force __u64)(__be32)(__saddr))) 343 #endif /* __BIG_ENDIAN */ 344 345 static inline bool inet_match(struct net *net, const struct sock *sk, 346 const __addrpair cookie, const __portpair ports, 347 int dif, int sdif) 348 { 349 if (!net_eq(sock_net(sk), net) || 350 sk->sk_portpair != ports || 351 sk->sk_addrpair != cookie) 352 return false; 353 354 /* READ_ONCE() paired with WRITE_ONCE() in sock_bindtoindex_locked() */ 355 return inet_sk_bound_dev_eq(net, READ_ONCE(sk->sk_bound_dev_if), dif, 356 sdif); 357 } 358 359 /* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need 360 * not check it for lookups anymore, thanks Alexey. -DaveM 361 */ 362 struct sock *__inet_lookup_established(struct net *net, 363 struct inet_hashinfo *hashinfo, 364 const __be32 saddr, const __be16 sport, 365 const __be32 daddr, const u16 hnum, 366 const int dif, const int sdif); 367 368 static inline struct sock * 369 inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo, 370 const __be32 saddr, const __be16 sport, 371 const __be32 daddr, const __be16 dport, 372 const int dif) 373 { 374 return __inet_lookup_established(net, hashinfo, saddr, sport, daddr, 375 ntohs(dport), dif, 0); 376 } 377 378 static inline struct sock *__inet_lookup(struct net *net, 379 struct inet_hashinfo *hashinfo, 380 struct sk_buff *skb, int doff, 381 const __be32 saddr, const __be16 sport, 382 const __be32 daddr, const __be16 dport, 383 const int dif, const int sdif, 384 bool *refcounted) 385 { 386 u16 hnum = ntohs(dport); 387 struct sock *sk; 388 389 sk = __inet_lookup_established(net, hashinfo, saddr, sport, 390 daddr, hnum, dif, sdif); 391 *refcounted = true; 392 if (sk) 393 return sk; 394 *refcounted = false; 395 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, 396 sport, daddr, hnum, dif, sdif); 397 } 398 399 static inline struct sock *inet_lookup(struct net *net, 400 struct inet_hashinfo *hashinfo, 401 struct sk_buff *skb, int doff, 402 const __be32 saddr, const __be16 sport, 403 const __be32 daddr, const __be16 dport, 404 const int dif) 405 { 406 struct sock *sk; 407 bool refcounted; 408 409 sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr, 410 dport, dif, 0, &refcounted); 411 412 if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt)) 413 sk = NULL; 414 return sk; 415 } 416 417 static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo, 418 struct sk_buff *skb, 419 int doff, 420 const __be16 sport, 421 const __be16 dport, 422 const int sdif, 423 bool *refcounted) 424 { 425 struct sock *sk = skb_steal_sock(skb, refcounted); 426 const struct iphdr *iph = ip_hdr(skb); 427 428 if (sk) 429 return sk; 430 431 return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb, 432 doff, iph->saddr, sport, 433 iph->daddr, dport, inet_iif(skb), sdif, 434 refcounted); 435 } 436 437 u32 inet6_ehashfn(const struct net *net, 438 const struct in6_addr *laddr, const u16 lport, 439 const struct in6_addr *faddr, const __be16 fport); 440 441 static inline void sk_daddr_set(struct sock *sk, __be32 addr) 442 { 443 sk->sk_daddr = addr; /* alias of inet_daddr */ 444 #if IS_ENABLED(CONFIG_IPV6) 445 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_daddr); 446 #endif 447 } 448 449 static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr) 450 { 451 sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */ 452 #if IS_ENABLED(CONFIG_IPV6) 453 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_rcv_saddr); 454 #endif 455 } 456 457 int __inet_hash_connect(struct inet_timewait_death_row *death_row, 458 struct sock *sk, u64 port_offset, 459 int (*check_established)(struct inet_timewait_death_row *, 460 struct sock *, __u16, 461 struct inet_timewait_sock **)); 462 463 int inet_hash_connect(struct inet_timewait_death_row *death_row, 464 struct sock *sk); 465 #endif /* _INET_HASHTABLES_H */ 466