1 /* 2 * INET An implementation of the TCP/IP protocol suite for the LINUX 3 * operating system. INET is implemented using the BSD Socket 4 * interface as the means of communication with the user level. 5 * 6 * Authors: Lotsa people, from code originally in tcp 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public License 10 * as published by the Free Software Foundation; either version 11 * 2 of the License, or (at your option) any later version. 12 */ 13 14 #ifndef _INET_HASHTABLES_H 15 #define _INET_HASHTABLES_H 16 17 18 #include <linux/interrupt.h> 19 #include <linux/ip.h> 20 #include <linux/ipv6.h> 21 #include <linux/list.h> 22 #include <linux/slab.h> 23 #include <linux/socket.h> 24 #include <linux/spinlock.h> 25 #include <linux/types.h> 26 #include <linux/wait.h> 27 28 #include <net/inet_connection_sock.h> 29 #include <net/inet_sock.h> 30 #include <net/sock.h> 31 #include <net/route.h> 32 #include <net/tcp_states.h> 33 #include <net/netns/hash.h> 34 35 #include <linux/refcount.h> 36 #include <asm/byteorder.h> 37 38 /* This is for all connections with a full identity, no wildcards. 39 * The 'e' prefix stands for Establish, but we really put all sockets 40 * but LISTEN ones. 41 */ 42 struct inet_ehash_bucket { 43 struct hlist_nulls_head chain; 44 }; 45 46 /* There are a few simple rules, which allow for local port reuse by 47 * an application. In essence: 48 * 49 * 1) Sockets bound to different interfaces may share a local port. 50 * Failing that, goto test 2. 51 * 2) If all sockets have sk->sk_reuse set, and none of them are in 52 * TCP_LISTEN state, the port may be shared. 53 * Failing that, goto test 3. 54 * 3) If all sockets are bound to a specific inet_sk(sk)->rcv_saddr local 55 * address, and none of them are the same, the port may be 56 * shared. 57 * Failing this, the port cannot be shared. 58 * 59 * The interesting point, is test #2. This is what an FTP server does 60 * all day. To optimize this case we use a specific flag bit defined 61 * below. As we add sockets to a bind bucket list, we perform a 62 * check of: (newsk->sk_reuse && (newsk->sk_state != TCP_LISTEN)) 63 * As long as all sockets added to a bind bucket pass this test, 64 * the flag bit will be set. 65 * The resulting situation is that tcp_v[46]_verify_bind() can just check 66 * for this flag bit, if it is set and the socket trying to bind has 67 * sk->sk_reuse set, we don't even have to walk the owners list at all, 68 * we return that it is ok to bind this socket to the requested local port. 69 * 70 * Sounds like a lot of work, but it is worth it. In a more naive 71 * implementation (ie. current FreeBSD etc.) the entire list of ports 72 * must be walked for each data port opened by an ftp server. Needless 73 * to say, this does not scale at all. With a couple thousand FTP 74 * users logged onto your box, isn't it nice to know that new data 75 * ports are created in O(1) time? I thought so. ;-) -DaveM 76 */ 77 #define FASTREUSEPORT_ANY 1 78 #define FASTREUSEPORT_STRICT 2 79 80 struct inet_bind_bucket { 81 possible_net_t ib_net; 82 unsigned short port; 83 signed char fastreuse; 84 signed char fastreuseport; 85 kuid_t fastuid; 86 #if IS_ENABLED(CONFIG_IPV6) 87 struct in6_addr fast_v6_rcv_saddr; 88 #endif 89 __be32 fast_rcv_saddr; 90 unsigned short fast_sk_family; 91 bool fast_ipv6_only; 92 struct hlist_node node; 93 struct hlist_head owners; 94 }; 95 96 static inline struct net *ib_net(struct inet_bind_bucket *ib) 97 { 98 return read_pnet(&ib->ib_net); 99 } 100 101 #define inet_bind_bucket_for_each(tb, head) \ 102 hlist_for_each_entry(tb, head, node) 103 104 struct inet_bind_hashbucket { 105 spinlock_t lock; 106 struct hlist_head chain; 107 }; 108 109 /* 110 * Sockets can be hashed in established or listening table 111 */ 112 struct inet_listen_hashbucket { 113 spinlock_t lock; 114 unsigned int count; 115 struct hlist_head head; 116 }; 117 118 /* This is for listening sockets, thus all sockets which possess wildcards. */ 119 #define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */ 120 121 struct inet_hashinfo { 122 /* This is for sockets with full identity only. Sockets here will 123 * always be without wildcards and will have the following invariant: 124 * 125 * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE 126 * 127 */ 128 struct inet_ehash_bucket *ehash; 129 spinlock_t *ehash_locks; 130 unsigned int ehash_mask; 131 unsigned int ehash_locks_mask; 132 133 /* Ok, let's try this, I give up, we do need a local binding 134 * TCP hash as well as the others for fast bind/connect. 135 */ 136 struct kmem_cache *bind_bucket_cachep; 137 struct inet_bind_hashbucket *bhash; 138 unsigned int bhash_size; 139 140 /* The 2nd listener table hashed by local port and address */ 141 unsigned int lhash2_mask; 142 struct inet_listen_hashbucket *lhash2; 143 144 /* All the above members are written once at bootup and 145 * never written again _or_ are predominantly read-access. 146 * 147 * Now align to a new cache line as all the following members 148 * might be often dirty. 149 */ 150 /* All sockets in TCP_LISTEN state will be in listening_hash. 151 * This is the only table where wildcard'd TCP sockets can 152 * exist. listening_hash is only hashed by local port number. 153 * If lhash2 is initialized, the same socket will also be hashed 154 * to lhash2 by port and address. 155 */ 156 struct inet_listen_hashbucket listening_hash[INET_LHTABLE_SIZE] 157 ____cacheline_aligned_in_smp; 158 }; 159 160 #define inet_lhash2_for_each_icsk_rcu(__icsk, list) \ 161 hlist_for_each_entry_rcu(__icsk, list, icsk_listen_portaddr_node) 162 163 static inline struct inet_listen_hashbucket * 164 inet_lhash2_bucket(struct inet_hashinfo *h, u32 hash) 165 { 166 return &h->lhash2[hash & h->lhash2_mask]; 167 } 168 169 static inline struct inet_ehash_bucket *inet_ehash_bucket( 170 struct inet_hashinfo *hashinfo, 171 unsigned int hash) 172 { 173 return &hashinfo->ehash[hash & hashinfo->ehash_mask]; 174 } 175 176 static inline spinlock_t *inet_ehash_lockp( 177 struct inet_hashinfo *hashinfo, 178 unsigned int hash) 179 { 180 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask]; 181 } 182 183 int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo); 184 185 static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo) 186 { 187 kvfree(hashinfo->ehash_locks); 188 hashinfo->ehash_locks = NULL; 189 } 190 191 struct inet_bind_bucket * 192 inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net, 193 struct inet_bind_hashbucket *head, 194 const unsigned short snum); 195 void inet_bind_bucket_destroy(struct kmem_cache *cachep, 196 struct inet_bind_bucket *tb); 197 198 static inline u32 inet_bhashfn(const struct net *net, const __u16 lport, 199 const u32 bhash_size) 200 { 201 return (lport + net_hash_mix(net)) & (bhash_size - 1); 202 } 203 204 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, 205 const unsigned short snum); 206 207 /* These can have wildcards, don't try too hard. */ 208 static inline u32 inet_lhashfn(const struct net *net, const unsigned short num) 209 { 210 return (num + net_hash_mix(net)) & (INET_LHTABLE_SIZE - 1); 211 } 212 213 static inline int inet_sk_listen_hashfn(const struct sock *sk) 214 { 215 return inet_lhashfn(sock_net(sk), inet_sk(sk)->inet_num); 216 } 217 218 /* Caller must disable local BH processing. */ 219 int __inet_inherit_port(const struct sock *sk, struct sock *child); 220 221 void inet_put_port(struct sock *sk); 222 223 void inet_hashinfo_init(struct inet_hashinfo *h); 224 void inet_hashinfo2_init(struct inet_hashinfo *h, const char *name, 225 unsigned long numentries, int scale, 226 unsigned long low_limit, 227 unsigned long high_limit); 228 229 bool inet_ehash_insert(struct sock *sk, struct sock *osk); 230 bool inet_ehash_nolisten(struct sock *sk, struct sock *osk); 231 int __inet_hash(struct sock *sk, struct sock *osk); 232 int inet_hash(struct sock *sk); 233 void inet_unhash(struct sock *sk); 234 235 struct sock *__inet_lookup_listener(struct net *net, 236 struct inet_hashinfo *hashinfo, 237 struct sk_buff *skb, int doff, 238 const __be32 saddr, const __be16 sport, 239 const __be32 daddr, 240 const unsigned short hnum, 241 const int dif, const int sdif); 242 243 static inline struct sock *inet_lookup_listener(struct net *net, 244 struct inet_hashinfo *hashinfo, 245 struct sk_buff *skb, int doff, 246 __be32 saddr, __be16 sport, 247 __be32 daddr, __be16 dport, int dif, int sdif) 248 { 249 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, sport, 250 daddr, ntohs(dport), dif, sdif); 251 } 252 253 /* Socket demux engine toys. */ 254 /* What happens here is ugly; there's a pair of adjacent fields in 255 struct inet_sock; __be16 dport followed by __u16 num. We want to 256 search by pair, so we combine the keys into a single 32bit value 257 and compare with 32bit value read from &...->dport. Let's at least 258 make sure that it's not mixed with anything else... 259 On 64bit targets we combine comparisons with pair of adjacent __be32 260 fields in the same way. 261 */ 262 #ifdef __BIG_ENDIAN 263 #define INET_COMBINED_PORTS(__sport, __dport) \ 264 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport))) 265 #else /* __LITTLE_ENDIAN */ 266 #define INET_COMBINED_PORTS(__sport, __dport) \ 267 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport))) 268 #endif 269 270 #if (BITS_PER_LONG == 64) 271 #ifdef __BIG_ENDIAN 272 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 273 const __addrpair __name = (__force __addrpair) ( \ 274 (((__force __u64)(__be32)(__saddr)) << 32) | \ 275 ((__force __u64)(__be32)(__daddr))) 276 #else /* __LITTLE_ENDIAN */ 277 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 278 const __addrpair __name = (__force __addrpair) ( \ 279 (((__force __u64)(__be32)(__daddr)) << 32) | \ 280 ((__force __u64)(__be32)(__saddr))) 281 #endif /* __BIG_ENDIAN */ 282 #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif, __sdif) \ 283 (((__sk)->sk_portpair == (__ports)) && \ 284 ((__sk)->sk_addrpair == (__cookie)) && \ 285 (!(__sk)->sk_bound_dev_if || \ 286 ((__sk)->sk_bound_dev_if == (__dif)) || \ 287 ((__sk)->sk_bound_dev_if == (__sdif))) && \ 288 net_eq(sock_net(__sk), (__net))) 289 #else /* 32-bit arch */ 290 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 291 const int __name __deprecated __attribute__((unused)) 292 293 #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif, __sdif) \ 294 (((__sk)->sk_portpair == (__ports)) && \ 295 ((__sk)->sk_daddr == (__saddr)) && \ 296 ((__sk)->sk_rcv_saddr == (__daddr)) && \ 297 (!(__sk)->sk_bound_dev_if || \ 298 ((__sk)->sk_bound_dev_if == (__dif)) || \ 299 ((__sk)->sk_bound_dev_if == (__sdif))) && \ 300 net_eq(sock_net(__sk), (__net))) 301 #endif /* 64-bit arch */ 302 303 /* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need 304 * not check it for lookups anymore, thanks Alexey. -DaveM 305 */ 306 struct sock *__inet_lookup_established(struct net *net, 307 struct inet_hashinfo *hashinfo, 308 const __be32 saddr, const __be16 sport, 309 const __be32 daddr, const u16 hnum, 310 const int dif, const int sdif); 311 312 static inline struct sock * 313 inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo, 314 const __be32 saddr, const __be16 sport, 315 const __be32 daddr, const __be16 dport, 316 const int dif) 317 { 318 return __inet_lookup_established(net, hashinfo, saddr, sport, daddr, 319 ntohs(dport), dif, 0); 320 } 321 322 static inline struct sock *__inet_lookup(struct net *net, 323 struct inet_hashinfo *hashinfo, 324 struct sk_buff *skb, int doff, 325 const __be32 saddr, const __be16 sport, 326 const __be32 daddr, const __be16 dport, 327 const int dif, const int sdif, 328 bool *refcounted) 329 { 330 u16 hnum = ntohs(dport); 331 struct sock *sk; 332 333 sk = __inet_lookup_established(net, hashinfo, saddr, sport, 334 daddr, hnum, dif, sdif); 335 *refcounted = true; 336 if (sk) 337 return sk; 338 *refcounted = false; 339 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, 340 sport, daddr, hnum, dif, sdif); 341 } 342 343 static inline struct sock *inet_lookup(struct net *net, 344 struct inet_hashinfo *hashinfo, 345 struct sk_buff *skb, int doff, 346 const __be32 saddr, const __be16 sport, 347 const __be32 daddr, const __be16 dport, 348 const int dif) 349 { 350 struct sock *sk; 351 bool refcounted; 352 353 sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr, 354 dport, dif, 0, &refcounted); 355 356 if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt)) 357 sk = NULL; 358 return sk; 359 } 360 361 static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo, 362 struct sk_buff *skb, 363 int doff, 364 const __be16 sport, 365 const __be16 dport, 366 const int sdif, 367 bool *refcounted) 368 { 369 struct sock *sk = skb_steal_sock(skb); 370 const struct iphdr *iph = ip_hdr(skb); 371 372 *refcounted = true; 373 if (sk) 374 return sk; 375 376 return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb, 377 doff, iph->saddr, sport, 378 iph->daddr, dport, inet_iif(skb), sdif, 379 refcounted); 380 } 381 382 u32 inet6_ehashfn(const struct net *net, 383 const struct in6_addr *laddr, const u16 lport, 384 const struct in6_addr *faddr, const __be16 fport); 385 386 static inline void sk_daddr_set(struct sock *sk, __be32 addr) 387 { 388 sk->sk_daddr = addr; /* alias of inet_daddr */ 389 #if IS_ENABLED(CONFIG_IPV6) 390 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_daddr); 391 #endif 392 } 393 394 static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr) 395 { 396 sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */ 397 #if IS_ENABLED(CONFIG_IPV6) 398 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_rcv_saddr); 399 #endif 400 } 401 402 int __inet_hash_connect(struct inet_timewait_death_row *death_row, 403 struct sock *sk, u32 port_offset, 404 int (*check_established)(struct inet_timewait_death_row *, 405 struct sock *, __u16, 406 struct inet_timewait_sock **)); 407 408 int inet_hash_connect(struct inet_timewait_death_row *death_row, 409 struct sock *sk); 410 #endif /* _INET_HASHTABLES_H */ 411