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 #include <linux/vmalloc.h> 28 29 #include <net/inet_connection_sock.h> 30 #include <net/inet_sock.h> 31 #include <net/sock.h> 32 #include <net/route.h> 33 #include <net/tcp_states.h> 34 #include <net/netns/hash.h> 35 36 #include <linux/atomic.h> 37 #include <asm/byteorder.h> 38 39 /* This is for all connections with a full identity, no wildcards. 40 * One chain is dedicated to TIME_WAIT sockets. 41 * I'll experiment with dynamic table growth later. 42 */ 43 struct inet_ehash_bucket { 44 struct hlist_nulls_head chain; 45 struct hlist_nulls_head twchain; 46 }; 47 48 /* There are a few simple rules, which allow for local port reuse by 49 * an application. In essence: 50 * 51 * 1) Sockets bound to different interfaces may share a local port. 52 * Failing that, goto test 2. 53 * 2) If all sockets have sk->sk_reuse set, and none of them are in 54 * TCP_LISTEN state, the port may be shared. 55 * Failing that, goto test 3. 56 * 3) If all sockets are bound to a specific inet_sk(sk)->rcv_saddr local 57 * address, and none of them are the same, the port may be 58 * shared. 59 * Failing this, the port cannot be shared. 60 * 61 * The interesting point, is test #2. This is what an FTP server does 62 * all day. To optimize this case we use a specific flag bit defined 63 * below. As we add sockets to a bind bucket list, we perform a 64 * check of: (newsk->sk_reuse && (newsk->sk_state != TCP_LISTEN)) 65 * As long as all sockets added to a bind bucket pass this test, 66 * the flag bit will be set. 67 * The resulting situation is that tcp_v[46]_verify_bind() can just check 68 * for this flag bit, if it is set and the socket trying to bind has 69 * sk->sk_reuse set, we don't even have to walk the owners list at all, 70 * we return that it is ok to bind this socket to the requested local port. 71 * 72 * Sounds like a lot of work, but it is worth it. In a more naive 73 * implementation (ie. current FreeBSD etc.) the entire list of ports 74 * must be walked for each data port opened by an ftp server. Needless 75 * to say, this does not scale at all. With a couple thousand FTP 76 * users logged onto your box, isn't it nice to know that new data 77 * ports are created in O(1) time? I thought so. ;-) -DaveM 78 */ 79 struct inet_bind_bucket { 80 #ifdef CONFIG_NET_NS 81 struct net *ib_net; 82 #endif 83 unsigned short port; 84 signed char fastreuse; 85 signed char fastreuseport; 86 kuid_t fastuid; 87 int num_owners; 88 struct hlist_node node; 89 struct hlist_head owners; 90 }; 91 92 static inline struct net *ib_net(struct inet_bind_bucket *ib) 93 { 94 return read_pnet(&ib->ib_net); 95 } 96 97 #define inet_bind_bucket_for_each(tb, head) \ 98 hlist_for_each_entry(tb, head, node) 99 100 struct inet_bind_hashbucket { 101 spinlock_t lock; 102 struct hlist_head chain; 103 }; 104 105 /* 106 * Sockets can be hashed in established or listening table 107 * We must use different 'nulls' end-of-chain value for listening 108 * hash table, or we might find a socket that was closed and 109 * reallocated/inserted into established hash table 110 */ 111 #define LISTENING_NULLS_BASE (1U << 29) 112 struct inet_listen_hashbucket { 113 spinlock_t lock; 114 struct hlist_nulls_head head; 115 }; 116 117 /* This is for listening sockets, thus all sockets which possess wildcards. */ 118 #define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */ 119 120 struct inet_hashinfo { 121 /* This is for sockets with full identity only. Sockets here will 122 * always be without wildcards and will have the following invariant: 123 * 124 * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE 125 * 126 * TIME_WAIT sockets use a separate chain (twchain). 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 inet_bind_hashbucket *bhash; 137 138 unsigned int bhash_size; 139 /* 4 bytes hole on 64 bit */ 140 141 struct kmem_cache *bind_bucket_cachep; 142 143 /* All the above members are written once at bootup and 144 * never written again _or_ are predominantly read-access. 145 * 146 * Now align to a new cache line as all the following members 147 * might be often dirty. 148 */ 149 /* All sockets in TCP_LISTEN state will be in here. This is the only 150 * table where wildcard'd TCP sockets can exist. Hash function here 151 * is just local port number. 152 */ 153 struct inet_listen_hashbucket listening_hash[INET_LHTABLE_SIZE] 154 ____cacheline_aligned_in_smp; 155 156 atomic_t bsockets; 157 }; 158 159 static inline struct inet_ehash_bucket *inet_ehash_bucket( 160 struct inet_hashinfo *hashinfo, 161 unsigned int hash) 162 { 163 return &hashinfo->ehash[hash & hashinfo->ehash_mask]; 164 } 165 166 static inline spinlock_t *inet_ehash_lockp( 167 struct inet_hashinfo *hashinfo, 168 unsigned int hash) 169 { 170 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask]; 171 } 172 173 static inline int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo) 174 { 175 unsigned int i, size = 256; 176 #if defined(CONFIG_PROVE_LOCKING) 177 unsigned int nr_pcpus = 2; 178 #else 179 unsigned int nr_pcpus = num_possible_cpus(); 180 #endif 181 if (nr_pcpus >= 4) 182 size = 512; 183 if (nr_pcpus >= 8) 184 size = 1024; 185 if (nr_pcpus >= 16) 186 size = 2048; 187 if (nr_pcpus >= 32) 188 size = 4096; 189 if (sizeof(spinlock_t) != 0) { 190 #ifdef CONFIG_NUMA 191 if (size * sizeof(spinlock_t) > PAGE_SIZE) 192 hashinfo->ehash_locks = vmalloc(size * sizeof(spinlock_t)); 193 else 194 #endif 195 hashinfo->ehash_locks = kmalloc(size * sizeof(spinlock_t), 196 GFP_KERNEL); 197 if (!hashinfo->ehash_locks) 198 return ENOMEM; 199 for (i = 0; i < size; i++) 200 spin_lock_init(&hashinfo->ehash_locks[i]); 201 } 202 hashinfo->ehash_locks_mask = size - 1; 203 return 0; 204 } 205 206 static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo) 207 { 208 if (hashinfo->ehash_locks) { 209 #ifdef CONFIG_NUMA 210 unsigned int size = (hashinfo->ehash_locks_mask + 1) * 211 sizeof(spinlock_t); 212 if (size > PAGE_SIZE) 213 vfree(hashinfo->ehash_locks); 214 else 215 #endif 216 kfree(hashinfo->ehash_locks); 217 hashinfo->ehash_locks = NULL; 218 } 219 } 220 221 struct inet_bind_bucket * 222 inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net, 223 struct inet_bind_hashbucket *head, 224 const unsigned short snum); 225 void inet_bind_bucket_destroy(struct kmem_cache *cachep, 226 struct inet_bind_bucket *tb); 227 228 static inline int inet_bhashfn(struct net *net, const __u16 lport, 229 const int bhash_size) 230 { 231 return (lport + net_hash_mix(net)) & (bhash_size - 1); 232 } 233 234 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, 235 const unsigned short snum); 236 237 /* These can have wildcards, don't try too hard. */ 238 static inline int inet_lhashfn(struct net *net, const unsigned short num) 239 { 240 return (num + net_hash_mix(net)) & (INET_LHTABLE_SIZE - 1); 241 } 242 243 static inline int inet_sk_listen_hashfn(const struct sock *sk) 244 { 245 return inet_lhashfn(sock_net(sk), inet_sk(sk)->inet_num); 246 } 247 248 /* Caller must disable local BH processing. */ 249 int __inet_inherit_port(struct sock *sk, struct sock *child); 250 251 void inet_put_port(struct sock *sk); 252 253 void inet_hashinfo_init(struct inet_hashinfo *h); 254 255 int __inet_hash_nolisten(struct sock *sk, struct inet_timewait_sock *tw); 256 void inet_hash(struct sock *sk); 257 void inet_unhash(struct sock *sk); 258 259 struct sock *__inet_lookup_listener(struct net *net, 260 struct inet_hashinfo *hashinfo, 261 const __be32 saddr, const __be16 sport, 262 const __be32 daddr, 263 const unsigned short hnum, 264 const int dif); 265 266 static inline struct sock *inet_lookup_listener(struct net *net, 267 struct inet_hashinfo *hashinfo, 268 __be32 saddr, __be16 sport, 269 __be32 daddr, __be16 dport, int dif) 270 { 271 return __inet_lookup_listener(net, hashinfo, saddr, sport, 272 daddr, ntohs(dport), dif); 273 } 274 275 /* Socket demux engine toys. */ 276 /* What happens here is ugly; there's a pair of adjacent fields in 277 struct inet_sock; __be16 dport followed by __u16 num. We want to 278 search by pair, so we combine the keys into a single 32bit value 279 and compare with 32bit value read from &...->dport. Let's at least 280 make sure that it's not mixed with anything else... 281 On 64bit targets we combine comparisons with pair of adjacent __be32 282 fields in the same way. 283 */ 284 #ifdef __BIG_ENDIAN 285 #define INET_COMBINED_PORTS(__sport, __dport) \ 286 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport))) 287 #else /* __LITTLE_ENDIAN */ 288 #define INET_COMBINED_PORTS(__sport, __dport) \ 289 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport))) 290 #endif 291 292 #if (BITS_PER_LONG == 64) 293 #ifdef __BIG_ENDIAN 294 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 295 const __addrpair __name = (__force __addrpair) ( \ 296 (((__force __u64)(__be32)(__saddr)) << 32) | \ 297 ((__force __u64)(__be32)(__daddr))); 298 #else /* __LITTLE_ENDIAN */ 299 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 300 const __addrpair __name = (__force __addrpair) ( \ 301 (((__force __u64)(__be32)(__daddr)) << 32) | \ 302 ((__force __u64)(__be32)(__saddr))); 303 #endif /* __BIG_ENDIAN */ 304 #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif) \ 305 ((inet_sk(__sk)->inet_portpair == (__ports)) && \ 306 (inet_sk(__sk)->inet_addrpair == (__cookie)) && \ 307 (!(__sk)->sk_bound_dev_if || \ 308 ((__sk)->sk_bound_dev_if == (__dif))) && \ 309 net_eq(sock_net(__sk), (__net))) 310 #define INET_TW_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif)\ 311 ((inet_twsk(__sk)->tw_portpair == (__ports)) && \ 312 (inet_twsk(__sk)->tw_addrpair == (__cookie)) && \ 313 (!(__sk)->sk_bound_dev_if || \ 314 ((__sk)->sk_bound_dev_if == (__dif))) && \ 315 net_eq(sock_net(__sk), (__net))) 316 #else /* 32-bit arch */ 317 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) 318 #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif) \ 319 ((inet_sk(__sk)->inet_portpair == (__ports)) && \ 320 (inet_sk(__sk)->inet_daddr == (__saddr)) && \ 321 (inet_sk(__sk)->inet_rcv_saddr == (__daddr)) && \ 322 (!(__sk)->sk_bound_dev_if || \ 323 ((__sk)->sk_bound_dev_if == (__dif))) && \ 324 net_eq(sock_net(__sk), (__net))) 325 #define INET_TW_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif) \ 326 ((inet_twsk(__sk)->tw_portpair == (__ports)) && \ 327 (inet_twsk(__sk)->tw_daddr == (__saddr)) && \ 328 (inet_twsk(__sk)->tw_rcv_saddr == (__daddr)) && \ 329 (!(__sk)->sk_bound_dev_if || \ 330 ((__sk)->sk_bound_dev_if == (__dif))) && \ 331 net_eq(sock_net(__sk), (__net))) 332 #endif /* 64-bit arch */ 333 334 /* 335 * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need 336 * not check it for lookups anymore, thanks Alexey. -DaveM 337 * 338 * Local BH must be disabled here. 339 */ 340 struct sock *__inet_lookup_established(struct net *net, 341 struct inet_hashinfo *hashinfo, 342 const __be32 saddr, const __be16 sport, 343 const __be32 daddr, const u16 hnum, 344 const int dif); 345 346 static inline struct sock * 347 inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo, 348 const __be32 saddr, const __be16 sport, 349 const __be32 daddr, const __be16 dport, 350 const int dif) 351 { 352 return __inet_lookup_established(net, hashinfo, saddr, sport, daddr, 353 ntohs(dport), dif); 354 } 355 356 static inline struct sock *__inet_lookup(struct net *net, 357 struct inet_hashinfo *hashinfo, 358 const __be32 saddr, const __be16 sport, 359 const __be32 daddr, const __be16 dport, 360 const int dif) 361 { 362 u16 hnum = ntohs(dport); 363 struct sock *sk = __inet_lookup_established(net, hashinfo, 364 saddr, sport, daddr, hnum, dif); 365 366 return sk ? : __inet_lookup_listener(net, hashinfo, saddr, sport, 367 daddr, hnum, dif); 368 } 369 370 static inline struct sock *inet_lookup(struct net *net, 371 struct inet_hashinfo *hashinfo, 372 const __be32 saddr, const __be16 sport, 373 const __be32 daddr, const __be16 dport, 374 const int dif) 375 { 376 struct sock *sk; 377 378 local_bh_disable(); 379 sk = __inet_lookup(net, hashinfo, saddr, sport, daddr, dport, dif); 380 local_bh_enable(); 381 382 return sk; 383 } 384 385 static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo, 386 struct sk_buff *skb, 387 const __be16 sport, 388 const __be16 dport) 389 { 390 struct sock *sk = skb_steal_sock(skb); 391 const struct iphdr *iph = ip_hdr(skb); 392 393 if (sk) 394 return sk; 395 else 396 return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, 397 iph->saddr, sport, 398 iph->daddr, dport, inet_iif(skb)); 399 } 400 401 int __inet_hash_connect(struct inet_timewait_death_row *death_row, 402 struct sock *sk, u32 port_offset, 403 int (*check_established)(struct inet_timewait_death_row *, 404 struct sock *, __u16, 405 struct inet_timewait_sock **), 406 int (*hash)(struct sock *sk, 407 struct inet_timewait_sock *twp)); 408 409 int inet_hash_connect(struct inet_timewait_death_row *death_row, 410 struct sock *sk); 411 #endif /* _INET_HASHTABLES_H */ 412