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/atomic.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 struct inet_bind_bucket { 78 possible_net_t ib_net; 79 unsigned short port; 80 signed char fastreuse; 81 signed char fastreuseport; 82 kuid_t fastuid; 83 int num_owners; 84 struct hlist_node node; 85 struct hlist_head owners; 86 }; 87 88 static inline struct net *ib_net(struct inet_bind_bucket *ib) 89 { 90 return read_pnet(&ib->ib_net); 91 } 92 93 #define inet_bind_bucket_for_each(tb, head) \ 94 hlist_for_each_entry(tb, head, node) 95 96 struct inet_bind_hashbucket { 97 spinlock_t lock; 98 struct hlist_head chain; 99 }; 100 101 /* 102 * Sockets can be hashed in established or listening table 103 * We must use different 'nulls' end-of-chain value for listening 104 * hash table, or we might find a socket that was closed and 105 * reallocated/inserted into established hash table 106 */ 107 #define LISTENING_NULLS_BASE (1U << 29) 108 struct inet_listen_hashbucket { 109 spinlock_t lock; 110 struct hlist_nulls_head head; 111 }; 112 113 /* This is for listening sockets, thus all sockets which possess wildcards. */ 114 #define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */ 115 116 struct inet_hashinfo { 117 /* This is for sockets with full identity only. Sockets here will 118 * always be without wildcards and will have the following invariant: 119 * 120 * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE 121 * 122 */ 123 struct inet_ehash_bucket *ehash; 124 spinlock_t *ehash_locks; 125 unsigned int ehash_mask; 126 unsigned int ehash_locks_mask; 127 128 /* Ok, let's try this, I give up, we do need a local binding 129 * TCP hash as well as the others for fast bind/connect. 130 */ 131 struct inet_bind_hashbucket *bhash; 132 133 unsigned int bhash_size; 134 /* 4 bytes hole on 64 bit */ 135 136 struct kmem_cache *bind_bucket_cachep; 137 138 /* All the above members are written once at bootup and 139 * never written again _or_ are predominantly read-access. 140 * 141 * Now align to a new cache line as all the following members 142 * might be often dirty. 143 */ 144 /* All sockets in TCP_LISTEN state will be in here. This is the only 145 * table where wildcard'd TCP sockets can exist. Hash function here 146 * is just local port number. 147 */ 148 struct inet_listen_hashbucket listening_hash[INET_LHTABLE_SIZE] 149 ____cacheline_aligned_in_smp; 150 }; 151 152 static inline struct inet_ehash_bucket *inet_ehash_bucket( 153 struct inet_hashinfo *hashinfo, 154 unsigned int hash) 155 { 156 return &hashinfo->ehash[hash & hashinfo->ehash_mask]; 157 } 158 159 static inline spinlock_t *inet_ehash_lockp( 160 struct inet_hashinfo *hashinfo, 161 unsigned int hash) 162 { 163 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask]; 164 } 165 166 int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo); 167 168 static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo) 169 { 170 kvfree(hashinfo->ehash_locks); 171 hashinfo->ehash_locks = NULL; 172 } 173 174 struct inet_bind_bucket * 175 inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net, 176 struct inet_bind_hashbucket *head, 177 const unsigned short snum); 178 void inet_bind_bucket_destroy(struct kmem_cache *cachep, 179 struct inet_bind_bucket *tb); 180 181 static inline u32 inet_bhashfn(const struct net *net, const __u16 lport, 182 const u32 bhash_size) 183 { 184 return (lport + net_hash_mix(net)) & (bhash_size - 1); 185 } 186 187 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, 188 const unsigned short snum); 189 190 /* These can have wildcards, don't try too hard. */ 191 static inline u32 inet_lhashfn(const struct net *net, const unsigned short num) 192 { 193 return (num + net_hash_mix(net)) & (INET_LHTABLE_SIZE - 1); 194 } 195 196 static inline int inet_sk_listen_hashfn(const struct sock *sk) 197 { 198 return inet_lhashfn(sock_net(sk), inet_sk(sk)->inet_num); 199 } 200 201 /* Caller must disable local BH processing. */ 202 int __inet_inherit_port(struct sock *sk, struct sock *child); 203 204 void inet_put_port(struct sock *sk); 205 206 void inet_hashinfo_init(struct inet_hashinfo *h); 207 208 void __inet_hash_nolisten(struct sock *sk, struct sock *osk); 209 void __inet_hash(struct sock *sk, struct sock *osk); 210 void inet_hash(struct sock *sk); 211 void inet_unhash(struct sock *sk); 212 213 struct sock *__inet_lookup_listener(struct net *net, 214 struct inet_hashinfo *hashinfo, 215 const __be32 saddr, const __be16 sport, 216 const __be32 daddr, 217 const unsigned short hnum, 218 const int dif); 219 220 static inline struct sock *inet_lookup_listener(struct net *net, 221 struct inet_hashinfo *hashinfo, 222 __be32 saddr, __be16 sport, 223 __be32 daddr, __be16 dport, int dif) 224 { 225 return __inet_lookup_listener(net, hashinfo, saddr, sport, 226 daddr, ntohs(dport), dif); 227 } 228 229 /* Socket demux engine toys. */ 230 /* What happens here is ugly; there's a pair of adjacent fields in 231 struct inet_sock; __be16 dport followed by __u16 num. We want to 232 search by pair, so we combine the keys into a single 32bit value 233 and compare with 32bit value read from &...->dport. Let's at least 234 make sure that it's not mixed with anything else... 235 On 64bit targets we combine comparisons with pair of adjacent __be32 236 fields in the same way. 237 */ 238 #ifdef __BIG_ENDIAN 239 #define INET_COMBINED_PORTS(__sport, __dport) \ 240 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport))) 241 #else /* __LITTLE_ENDIAN */ 242 #define INET_COMBINED_PORTS(__sport, __dport) \ 243 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport))) 244 #endif 245 246 #if (BITS_PER_LONG == 64) 247 #ifdef __BIG_ENDIAN 248 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 249 const __addrpair __name = (__force __addrpair) ( \ 250 (((__force __u64)(__be32)(__saddr)) << 32) | \ 251 ((__force __u64)(__be32)(__daddr))) 252 #else /* __LITTLE_ENDIAN */ 253 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 254 const __addrpair __name = (__force __addrpair) ( \ 255 (((__force __u64)(__be32)(__daddr)) << 32) | \ 256 ((__force __u64)(__be32)(__saddr))) 257 #endif /* __BIG_ENDIAN */ 258 #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif) \ 259 (((__sk)->sk_portpair == (__ports)) && \ 260 ((__sk)->sk_addrpair == (__cookie)) && \ 261 (!(__sk)->sk_bound_dev_if || \ 262 ((__sk)->sk_bound_dev_if == (__dif))) && \ 263 net_eq(sock_net(__sk), (__net))) 264 #else /* 32-bit arch */ 265 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 266 const int __name __deprecated __attribute__((unused)) 267 268 #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif) \ 269 (((__sk)->sk_portpair == (__ports)) && \ 270 ((__sk)->sk_daddr == (__saddr)) && \ 271 ((__sk)->sk_rcv_saddr == (__daddr)) && \ 272 (!(__sk)->sk_bound_dev_if || \ 273 ((__sk)->sk_bound_dev_if == (__dif))) && \ 274 net_eq(sock_net(__sk), (__net))) 275 #endif /* 64-bit arch */ 276 277 /* 278 * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need 279 * not check it for lookups anymore, thanks Alexey. -DaveM 280 * 281 * Local BH must be disabled here. 282 */ 283 struct sock *__inet_lookup_established(struct net *net, 284 struct inet_hashinfo *hashinfo, 285 const __be32 saddr, const __be16 sport, 286 const __be32 daddr, const u16 hnum, 287 const int dif); 288 289 static inline struct sock * 290 inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo, 291 const __be32 saddr, const __be16 sport, 292 const __be32 daddr, const __be16 dport, 293 const int dif) 294 { 295 return __inet_lookup_established(net, hashinfo, saddr, sport, daddr, 296 ntohs(dport), dif); 297 } 298 299 static inline struct sock *__inet_lookup(struct net *net, 300 struct inet_hashinfo *hashinfo, 301 const __be32 saddr, const __be16 sport, 302 const __be32 daddr, const __be16 dport, 303 const int dif) 304 { 305 u16 hnum = ntohs(dport); 306 struct sock *sk = __inet_lookup_established(net, hashinfo, 307 saddr, sport, daddr, hnum, dif); 308 309 return sk ? : __inet_lookup_listener(net, hashinfo, saddr, sport, 310 daddr, hnum, dif); 311 } 312 313 static inline struct sock *inet_lookup(struct net *net, 314 struct inet_hashinfo *hashinfo, 315 const __be32 saddr, const __be16 sport, 316 const __be32 daddr, const __be16 dport, 317 const int dif) 318 { 319 struct sock *sk; 320 321 local_bh_disable(); 322 sk = __inet_lookup(net, hashinfo, saddr, sport, daddr, dport, dif); 323 local_bh_enable(); 324 325 return sk; 326 } 327 328 static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo, 329 struct sk_buff *skb, 330 const __be16 sport, 331 const __be16 dport) 332 { 333 struct sock *sk = skb_steal_sock(skb); 334 const struct iphdr *iph = ip_hdr(skb); 335 336 if (sk) 337 return sk; 338 else 339 return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, 340 iph->saddr, sport, 341 iph->daddr, dport, inet_iif(skb)); 342 } 343 344 u32 sk_ehashfn(const struct sock *sk); 345 u32 inet6_ehashfn(const struct net *net, 346 const struct in6_addr *laddr, const u16 lport, 347 const struct in6_addr *faddr, const __be16 fport); 348 349 static inline void sk_daddr_set(struct sock *sk, __be32 addr) 350 { 351 sk->sk_daddr = addr; /* alias of inet_daddr */ 352 #if IS_ENABLED(CONFIG_IPV6) 353 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_daddr); 354 #endif 355 } 356 357 static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr) 358 { 359 sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */ 360 #if IS_ENABLED(CONFIG_IPV6) 361 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_rcv_saddr); 362 #endif 363 } 364 365 int __inet_hash_connect(struct inet_timewait_death_row *death_row, 366 struct sock *sk, u32 port_offset, 367 int (*check_established)(struct inet_timewait_death_row *, 368 struct sock *, __u16, 369 struct inet_timewait_sock **)); 370 371 int inet_hash_connect(struct inet_timewait_death_row *death_row, 372 struct sock *sk); 373 #endif /* _INET_HASHTABLES_H */ 374