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 */ 104 struct inet_listen_hashbucket { 105 spinlock_t lock; 106 struct hlist_head head; 107 }; 108 109 /* This is for listening sockets, thus all sockets which possess wildcards. */ 110 #define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */ 111 112 struct inet_hashinfo { 113 /* This is for sockets with full identity only. Sockets here will 114 * always be without wildcards and will have the following invariant: 115 * 116 * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE 117 * 118 */ 119 struct inet_ehash_bucket *ehash; 120 spinlock_t *ehash_locks; 121 unsigned int ehash_mask; 122 unsigned int ehash_locks_mask; 123 124 /* Ok, let's try this, I give up, we do need a local binding 125 * TCP hash as well as the others for fast bind/connect. 126 */ 127 struct inet_bind_hashbucket *bhash; 128 129 unsigned int bhash_size; 130 /* 4 bytes hole on 64 bit */ 131 132 struct kmem_cache *bind_bucket_cachep; 133 134 /* All the above members are written once at bootup and 135 * never written again _or_ are predominantly read-access. 136 * 137 * Now align to a new cache line as all the following members 138 * might be often dirty. 139 */ 140 /* All sockets in TCP_LISTEN state will be in here. This is the only 141 * table where wildcard'd TCP sockets can exist. Hash function here 142 * is just local port number. 143 */ 144 struct inet_listen_hashbucket listening_hash[INET_LHTABLE_SIZE] 145 ____cacheline_aligned_in_smp; 146 }; 147 148 static inline struct inet_ehash_bucket *inet_ehash_bucket( 149 struct inet_hashinfo *hashinfo, 150 unsigned int hash) 151 { 152 return &hashinfo->ehash[hash & hashinfo->ehash_mask]; 153 } 154 155 static inline spinlock_t *inet_ehash_lockp( 156 struct inet_hashinfo *hashinfo, 157 unsigned int hash) 158 { 159 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask]; 160 } 161 162 int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo); 163 164 static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo) 165 { 166 kvfree(hashinfo->ehash_locks); 167 hashinfo->ehash_locks = NULL; 168 } 169 170 struct inet_bind_bucket * 171 inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net, 172 struct inet_bind_hashbucket *head, 173 const unsigned short snum); 174 void inet_bind_bucket_destroy(struct kmem_cache *cachep, 175 struct inet_bind_bucket *tb); 176 177 static inline u32 inet_bhashfn(const struct net *net, const __u16 lport, 178 const u32 bhash_size) 179 { 180 return (lport + net_hash_mix(net)) & (bhash_size - 1); 181 } 182 183 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, 184 const unsigned short snum); 185 186 /* These can have wildcards, don't try too hard. */ 187 static inline u32 inet_lhashfn(const struct net *net, const unsigned short num) 188 { 189 return (num + net_hash_mix(net)) & (INET_LHTABLE_SIZE - 1); 190 } 191 192 static inline int inet_sk_listen_hashfn(const struct sock *sk) 193 { 194 return inet_lhashfn(sock_net(sk), inet_sk(sk)->inet_num); 195 } 196 197 /* Caller must disable local BH processing. */ 198 int __inet_inherit_port(const struct sock *sk, struct sock *child); 199 200 void inet_put_port(struct sock *sk); 201 202 void inet_hashinfo_init(struct inet_hashinfo *h); 203 204 bool inet_ehash_insert(struct sock *sk, struct sock *osk); 205 bool inet_ehash_nolisten(struct sock *sk, struct sock *osk); 206 int __inet_hash(struct sock *sk, struct sock *osk, 207 int (*saddr_same)(const struct sock *sk1, 208 const struct sock *sk2, 209 bool match_wildcard)); 210 int 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 struct sk_buff *skb, int doff, 216 const __be32 saddr, const __be16 sport, 217 const __be32 daddr, 218 const unsigned short hnum, 219 const int dif); 220 221 static inline struct sock *inet_lookup_listener(struct net *net, 222 struct inet_hashinfo *hashinfo, 223 struct sk_buff *skb, int doff, 224 __be32 saddr, __be16 sport, 225 __be32 daddr, __be16 dport, int dif) 226 { 227 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, sport, 228 daddr, ntohs(dport), dif); 229 } 230 231 /* Socket demux engine toys. */ 232 /* What happens here is ugly; there's a pair of adjacent fields in 233 struct inet_sock; __be16 dport followed by __u16 num. We want to 234 search by pair, so we combine the keys into a single 32bit value 235 and compare with 32bit value read from &...->dport. Let's at least 236 make sure that it's not mixed with anything else... 237 On 64bit targets we combine comparisons with pair of adjacent __be32 238 fields in the same way. 239 */ 240 #ifdef __BIG_ENDIAN 241 #define INET_COMBINED_PORTS(__sport, __dport) \ 242 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport))) 243 #else /* __LITTLE_ENDIAN */ 244 #define INET_COMBINED_PORTS(__sport, __dport) \ 245 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport))) 246 #endif 247 248 #if (BITS_PER_LONG == 64) 249 #ifdef __BIG_ENDIAN 250 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 251 const __addrpair __name = (__force __addrpair) ( \ 252 (((__force __u64)(__be32)(__saddr)) << 32) | \ 253 ((__force __u64)(__be32)(__daddr))) 254 #else /* __LITTLE_ENDIAN */ 255 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 256 const __addrpair __name = (__force __addrpair) ( \ 257 (((__force __u64)(__be32)(__daddr)) << 32) | \ 258 ((__force __u64)(__be32)(__saddr))) 259 #endif /* __BIG_ENDIAN */ 260 #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif) \ 261 (((__sk)->sk_portpair == (__ports)) && \ 262 ((__sk)->sk_addrpair == (__cookie)) && \ 263 (!(__sk)->sk_bound_dev_if || \ 264 ((__sk)->sk_bound_dev_if == (__dif))) && \ 265 net_eq(sock_net(__sk), (__net))) 266 #else /* 32-bit arch */ 267 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 268 const int __name __deprecated __attribute__((unused)) 269 270 #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif) \ 271 (((__sk)->sk_portpair == (__ports)) && \ 272 ((__sk)->sk_daddr == (__saddr)) && \ 273 ((__sk)->sk_rcv_saddr == (__daddr)) && \ 274 (!(__sk)->sk_bound_dev_if || \ 275 ((__sk)->sk_bound_dev_if == (__dif))) && \ 276 net_eq(sock_net(__sk), (__net))) 277 #endif /* 64-bit arch */ 278 279 /* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need 280 * not check it for lookups anymore, thanks Alexey. -DaveM 281 */ 282 struct sock *__inet_lookup_established(struct net *net, 283 struct inet_hashinfo *hashinfo, 284 const __be32 saddr, const __be16 sport, 285 const __be32 daddr, const u16 hnum, 286 const int dif); 287 288 static inline struct sock * 289 inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo, 290 const __be32 saddr, const __be16 sport, 291 const __be32 daddr, const __be16 dport, 292 const int dif) 293 { 294 return __inet_lookup_established(net, hashinfo, saddr, sport, daddr, 295 ntohs(dport), dif); 296 } 297 298 static inline struct sock *__inet_lookup(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, const __be16 dport, 303 const int dif, 304 bool *refcounted) 305 { 306 u16 hnum = ntohs(dport); 307 struct sock *sk; 308 309 sk = __inet_lookup_established(net, hashinfo, saddr, sport, 310 daddr, hnum, dif); 311 *refcounted = true; 312 if (sk) 313 return sk; 314 *refcounted = false; 315 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, 316 sport, daddr, hnum, dif); 317 } 318 319 static inline struct sock *inet_lookup(struct net *net, 320 struct inet_hashinfo *hashinfo, 321 struct sk_buff *skb, int doff, 322 const __be32 saddr, const __be16 sport, 323 const __be32 daddr, const __be16 dport, 324 const int dif) 325 { 326 struct sock *sk; 327 bool refcounted; 328 329 sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr, 330 dport, dif, &refcounted); 331 332 if (sk && !refcounted && !atomic_inc_not_zero(&sk->sk_refcnt)) 333 sk = NULL; 334 return sk; 335 } 336 337 static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo, 338 struct sk_buff *skb, 339 int doff, 340 const __be16 sport, 341 const __be16 dport, 342 bool *refcounted) 343 { 344 struct sock *sk = skb_steal_sock(skb); 345 const struct iphdr *iph = ip_hdr(skb); 346 347 *refcounted = true; 348 if (sk) 349 return sk; 350 351 return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb, 352 doff, iph->saddr, sport, 353 iph->daddr, dport, inet_iif(skb), 354 refcounted); 355 } 356 357 u32 sk_ehashfn(const struct sock *sk); 358 u32 inet6_ehashfn(const struct net *net, 359 const struct in6_addr *laddr, const u16 lport, 360 const struct in6_addr *faddr, const __be16 fport); 361 362 static inline void sk_daddr_set(struct sock *sk, __be32 addr) 363 { 364 sk->sk_daddr = addr; /* alias of inet_daddr */ 365 #if IS_ENABLED(CONFIG_IPV6) 366 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_daddr); 367 #endif 368 } 369 370 static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr) 371 { 372 sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */ 373 #if IS_ENABLED(CONFIG_IPV6) 374 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_rcv_saddr); 375 #endif 376 } 377 378 int __inet_hash_connect(struct inet_timewait_death_row *death_row, 379 struct sock *sk, u32 port_offset, 380 int (*check_established)(struct inet_timewait_death_row *, 381 struct sock *, __u16, 382 struct inet_timewait_sock **)); 383 384 int inet_hash_connect(struct inet_timewait_death_row *death_row, 385 struct sock *sk); 386 #endif /* _INET_HASHTABLES_H */ 387