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 <asm/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 short fastreuse; 85 struct hlist_node node; 86 struct hlist_head owners; 87 }; 88 89 static inline struct net *ib_net(struct inet_bind_bucket *ib) 90 { 91 return read_pnet(&ib->ib_net); 92 } 93 94 #define inet_bind_bucket_for_each(tb, node, head) \ 95 hlist_for_each_entry(tb, node, head, node) 96 97 struct inet_bind_hashbucket { 98 spinlock_t lock; 99 struct hlist_head chain; 100 }; 101 102 /* 103 * Sockets can be hashed in established or listening table 104 * We must use different 'nulls' end-of-chain value for listening 105 * hash table, or we might find a socket that was closed and 106 * reallocated/inserted into established hash table 107 */ 108 #define LISTENING_NULLS_BASE (1U << 29) 109 struct inet_listen_hashbucket { 110 spinlock_t lock; 111 struct hlist_nulls_head head; 112 }; 113 114 /* This is for listening sockets, thus all sockets which possess wildcards. */ 115 #define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */ 116 117 struct inet_hashinfo { 118 /* This is for sockets with full identity only. Sockets here will 119 * always be without wildcards and will have the following invariant: 120 * 121 * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE 122 * 123 * TIME_WAIT sockets use a separate chain (twchain). 124 */ 125 struct inet_ehash_bucket *ehash; 126 spinlock_t *ehash_locks; 127 unsigned int ehash_size; 128 unsigned int ehash_locks_mask; 129 130 /* Ok, let's try this, I give up, we do need a local binding 131 * TCP hash as well as the others for fast bind/connect. 132 */ 133 struct inet_bind_hashbucket *bhash; 134 135 unsigned int bhash_size; 136 /* Note : 4 bytes padding on 64 bit arches */ 137 138 struct kmem_cache *bind_bucket_cachep; 139 140 /* All the above members are written once at bootup and 141 * never written again _or_ are predominantly read-access. 142 * 143 * Now align to a new cache line as all the following members 144 * might be often dirty. 145 */ 146 /* All sockets in TCP_LISTEN state will be in here. This is the only 147 * table where wildcard'd TCP sockets can exist. Hash function here 148 * is just local port number. 149 */ 150 struct inet_listen_hashbucket listening_hash[INET_LHTABLE_SIZE] 151 ____cacheline_aligned_in_smp; 152 153 }; 154 155 static inline struct inet_ehash_bucket *inet_ehash_bucket( 156 struct inet_hashinfo *hashinfo, 157 unsigned int hash) 158 { 159 return &hashinfo->ehash[hash & (hashinfo->ehash_size - 1)]; 160 } 161 162 static inline spinlock_t *inet_ehash_lockp( 163 struct inet_hashinfo *hashinfo, 164 unsigned int hash) 165 { 166 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask]; 167 } 168 169 static inline int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo) 170 { 171 unsigned int i, size = 256; 172 #if defined(CONFIG_PROVE_LOCKING) 173 unsigned int nr_pcpus = 2; 174 #else 175 unsigned int nr_pcpus = num_possible_cpus(); 176 #endif 177 if (nr_pcpus >= 4) 178 size = 512; 179 if (nr_pcpus >= 8) 180 size = 1024; 181 if (nr_pcpus >= 16) 182 size = 2048; 183 if (nr_pcpus >= 32) 184 size = 4096; 185 if (sizeof(spinlock_t) != 0) { 186 #ifdef CONFIG_NUMA 187 if (size * sizeof(spinlock_t) > PAGE_SIZE) 188 hashinfo->ehash_locks = vmalloc(size * sizeof(spinlock_t)); 189 else 190 #endif 191 hashinfo->ehash_locks = kmalloc(size * sizeof(spinlock_t), 192 GFP_KERNEL); 193 if (!hashinfo->ehash_locks) 194 return ENOMEM; 195 for (i = 0; i < size; i++) 196 spin_lock_init(&hashinfo->ehash_locks[i]); 197 } 198 hashinfo->ehash_locks_mask = size - 1; 199 return 0; 200 } 201 202 static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo) 203 { 204 if (hashinfo->ehash_locks) { 205 #ifdef CONFIG_NUMA 206 unsigned int size = (hashinfo->ehash_locks_mask + 1) * 207 sizeof(spinlock_t); 208 if (size > PAGE_SIZE) 209 vfree(hashinfo->ehash_locks); 210 else 211 #endif 212 kfree(hashinfo->ehash_locks); 213 hashinfo->ehash_locks = NULL; 214 } 215 } 216 217 extern struct inet_bind_bucket * 218 inet_bind_bucket_create(struct kmem_cache *cachep, 219 struct net *net, 220 struct inet_bind_hashbucket *head, 221 const unsigned short snum); 222 extern void inet_bind_bucket_destroy(struct kmem_cache *cachep, 223 struct inet_bind_bucket *tb); 224 225 static inline int inet_bhashfn(struct net *net, 226 const __u16 lport, const int bhash_size) 227 { 228 return (lport + net_hash_mix(net)) & (bhash_size - 1); 229 } 230 231 extern void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, 232 const unsigned short snum); 233 234 /* These can have wildcards, don't try too hard. */ 235 static inline int inet_lhashfn(struct net *net, const unsigned short num) 236 { 237 return (num + net_hash_mix(net)) & (INET_LHTABLE_SIZE - 1); 238 } 239 240 static inline int inet_sk_listen_hashfn(const struct sock *sk) 241 { 242 return inet_lhashfn(sock_net(sk), inet_sk(sk)->num); 243 } 244 245 /* Caller must disable local BH processing. */ 246 extern void __inet_inherit_port(struct sock *sk, struct sock *child); 247 248 extern void inet_put_port(struct sock *sk); 249 250 void inet_hashinfo_init(struct inet_hashinfo *h); 251 252 extern void __inet_hash_nolisten(struct sock *sk); 253 extern void inet_hash(struct sock *sk); 254 extern void inet_unhash(struct sock *sk); 255 256 extern struct sock *__inet_lookup_listener(struct net *net, 257 struct inet_hashinfo *hashinfo, 258 const __be32 daddr, 259 const unsigned short hnum, 260 const int dif); 261 262 static inline struct sock *inet_lookup_listener(struct net *net, 263 struct inet_hashinfo *hashinfo, 264 __be32 daddr, __be16 dport, int dif) 265 { 266 return __inet_lookup_listener(net, hashinfo, daddr, ntohs(dport), dif); 267 } 268 269 /* Socket demux engine toys. */ 270 /* What happens here is ugly; there's a pair of adjacent fields in 271 struct inet_sock; __be16 dport followed by __u16 num. We want to 272 search by pair, so we combine the keys into a single 32bit value 273 and compare with 32bit value read from &...->dport. Let's at least 274 make sure that it's not mixed with anything else... 275 On 64bit targets we combine comparisons with pair of adjacent __be32 276 fields in the same way. 277 */ 278 typedef __u32 __bitwise __portpair; 279 #ifdef __BIG_ENDIAN 280 #define INET_COMBINED_PORTS(__sport, __dport) \ 281 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport))) 282 #else /* __LITTLE_ENDIAN */ 283 #define INET_COMBINED_PORTS(__sport, __dport) \ 284 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport))) 285 #endif 286 287 #if (BITS_PER_LONG == 64) 288 typedef __u64 __bitwise __addrpair; 289 #ifdef __BIG_ENDIAN 290 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 291 const __addrpair __name = (__force __addrpair) ( \ 292 (((__force __u64)(__be32)(__saddr)) << 32) | \ 293 ((__force __u64)(__be32)(__daddr))); 294 #else /* __LITTLE_ENDIAN */ 295 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 296 const __addrpair __name = (__force __addrpair) ( \ 297 (((__force __u64)(__be32)(__daddr)) << 32) | \ 298 ((__force __u64)(__be32)(__saddr))); 299 #endif /* __BIG_ENDIAN */ 300 #define INET_MATCH(__sk, __net, __hash, __cookie, __saddr, __daddr, __ports, __dif)\ 301 (((__sk)->sk_hash == (__hash)) && net_eq(sock_net(__sk), (__net)) && \ 302 ((*((__addrpair *)&(inet_sk(__sk)->daddr))) == (__cookie)) && \ 303 ((*((__portpair *)&(inet_sk(__sk)->dport))) == (__ports)) && \ 304 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 305 #define INET_TW_MATCH(__sk, __net, __hash, __cookie, __saddr, __daddr, __ports, __dif)\ 306 (((__sk)->sk_hash == (__hash)) && net_eq(sock_net(__sk), (__net)) && \ 307 ((*((__addrpair *)&(inet_twsk(__sk)->tw_daddr))) == (__cookie)) && \ 308 ((*((__portpair *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) && \ 309 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 310 #else /* 32-bit arch */ 311 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) 312 #define INET_MATCH(__sk, __net, __hash, __cookie, __saddr, __daddr, __ports, __dif) \ 313 (((__sk)->sk_hash == (__hash)) && net_eq(sock_net(__sk), (__net)) && \ 314 (inet_sk(__sk)->daddr == (__saddr)) && \ 315 (inet_sk(__sk)->rcv_saddr == (__daddr)) && \ 316 ((*((__portpair *)&(inet_sk(__sk)->dport))) == (__ports)) && \ 317 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 318 #define INET_TW_MATCH(__sk, __net, __hash,__cookie, __saddr, __daddr, __ports, __dif) \ 319 (((__sk)->sk_hash == (__hash)) && net_eq(sock_net(__sk), (__net)) && \ 320 (inet_twsk(__sk)->tw_daddr == (__saddr)) && \ 321 (inet_twsk(__sk)->tw_rcv_saddr == (__daddr)) && \ 322 ((*((__portpair *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) && \ 323 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 324 #endif /* 64-bit arch */ 325 326 /* 327 * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need 328 * not check it for lookups anymore, thanks Alexey. -DaveM 329 * 330 * Local BH must be disabled here. 331 */ 332 extern struct sock * __inet_lookup_established(struct net *net, 333 struct inet_hashinfo *hashinfo, 334 const __be32 saddr, const __be16 sport, 335 const __be32 daddr, const u16 hnum, const int dif); 336 337 static inline struct sock * 338 inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo, 339 const __be32 saddr, const __be16 sport, 340 const __be32 daddr, const __be16 dport, 341 const int dif) 342 { 343 return __inet_lookup_established(net, hashinfo, saddr, sport, daddr, 344 ntohs(dport), dif); 345 } 346 347 static inline struct sock *__inet_lookup(struct net *net, 348 struct inet_hashinfo *hashinfo, 349 const __be32 saddr, const __be16 sport, 350 const __be32 daddr, const __be16 dport, 351 const int dif) 352 { 353 u16 hnum = ntohs(dport); 354 struct sock *sk = __inet_lookup_established(net, hashinfo, 355 saddr, sport, daddr, hnum, dif); 356 357 return sk ? : __inet_lookup_listener(net, hashinfo, daddr, hnum, dif); 358 } 359 360 static inline struct sock *inet_lookup(struct net *net, 361 struct inet_hashinfo *hashinfo, 362 const __be32 saddr, const __be16 sport, 363 const __be32 daddr, const __be16 dport, 364 const int dif) 365 { 366 struct sock *sk; 367 368 local_bh_disable(); 369 sk = __inet_lookup(net, hashinfo, saddr, sport, daddr, dport, dif); 370 local_bh_enable(); 371 372 return sk; 373 } 374 375 static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo, 376 struct sk_buff *skb, 377 const __be16 sport, 378 const __be16 dport) 379 { 380 struct sock *sk; 381 const struct iphdr *iph = ip_hdr(skb); 382 383 if (unlikely(sk = skb_steal_sock(skb))) 384 return sk; 385 else 386 return __inet_lookup(dev_net(skb->dst->dev), hashinfo, 387 iph->saddr, sport, 388 iph->daddr, dport, inet_iif(skb)); 389 } 390 391 extern int __inet_hash_connect(struct inet_timewait_death_row *death_row, 392 struct sock *sk, u32 port_offset, 393 int (*check_established)(struct inet_timewait_death_row *, 394 struct sock *, __u16, struct inet_timewait_sock **), 395 void (*hash)(struct sock *sk)); 396 extern int inet_hash_connect(struct inet_timewait_death_row *death_row, 397 struct sock *sk); 398 #endif /* _INET_HASHTABLES_H */ 399