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 #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 struct hlist_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 */ 127 struct inet_ehash_bucket *ehash; 128 spinlock_t *ehash_locks; 129 unsigned int ehash_mask; 130 unsigned int ehash_locks_mask; 131 132 /* Ok, let's try this, I give up, we do need a local binding 133 * TCP hash as well as the others for fast bind/connect. 134 */ 135 struct inet_bind_hashbucket *bhash; 136 137 unsigned int bhash_size; 138 /* 4 bytes hole on 64 bit */ 139 140 struct kmem_cache *bind_bucket_cachep; 141 142 /* All the above members are written once at bootup and 143 * never written again _or_ are predominantly read-access. 144 * 145 * Now align to a new cache line as all the following members 146 * might be often dirty. 147 */ 148 /* All sockets in TCP_LISTEN state will be in here. This is the only 149 * table where wildcard'd TCP sockets can exist. Hash function here 150 * is just local port number. 151 */ 152 struct inet_listen_hashbucket listening_hash[INET_LHTABLE_SIZE] 153 ____cacheline_aligned_in_smp; 154 }; 155 156 static inline struct inet_ehash_bucket *inet_ehash_bucket( 157 struct inet_hashinfo *hashinfo, 158 unsigned int hash) 159 { 160 return &hashinfo->ehash[hash & hashinfo->ehash_mask]; 161 } 162 163 static inline spinlock_t *inet_ehash_lockp( 164 struct inet_hashinfo *hashinfo, 165 unsigned int hash) 166 { 167 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask]; 168 } 169 170 int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo); 171 172 static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo) 173 { 174 kvfree(hashinfo->ehash_locks); 175 hashinfo->ehash_locks = NULL; 176 } 177 178 struct inet_bind_bucket * 179 inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net, 180 struct inet_bind_hashbucket *head, 181 const unsigned short snum); 182 void inet_bind_bucket_destroy(struct kmem_cache *cachep, 183 struct inet_bind_bucket *tb); 184 185 static inline u32 inet_bhashfn(const struct net *net, const __u16 lport, 186 const u32 bhash_size) 187 { 188 return (lport + net_hash_mix(net)) & (bhash_size - 1); 189 } 190 191 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, 192 const unsigned short snum); 193 194 /* These can have wildcards, don't try too hard. */ 195 static inline u32 inet_lhashfn(const struct net *net, const unsigned short num) 196 { 197 return (num + net_hash_mix(net)) & (INET_LHTABLE_SIZE - 1); 198 } 199 200 static inline int inet_sk_listen_hashfn(const struct sock *sk) 201 { 202 return inet_lhashfn(sock_net(sk), inet_sk(sk)->inet_num); 203 } 204 205 /* Caller must disable local BH processing. */ 206 int __inet_inherit_port(const struct sock *sk, struct sock *child); 207 208 void inet_put_port(struct sock *sk); 209 210 void inet_hashinfo_init(struct inet_hashinfo *h); 211 212 bool inet_ehash_insert(struct sock *sk, struct sock *osk); 213 bool inet_ehash_nolisten(struct sock *sk, struct sock *osk); 214 int __inet_hash(struct sock *sk, struct sock *osk); 215 int inet_hash(struct sock *sk); 216 void inet_unhash(struct sock *sk); 217 218 struct sock *__inet_lookup_listener(struct net *net, 219 struct inet_hashinfo *hashinfo, 220 struct sk_buff *skb, int doff, 221 const __be32 saddr, const __be16 sport, 222 const __be32 daddr, 223 const unsigned short hnum, 224 const int dif); 225 226 static inline struct sock *inet_lookup_listener(struct net *net, 227 struct inet_hashinfo *hashinfo, 228 struct sk_buff *skb, int doff, 229 __be32 saddr, __be16 sport, 230 __be32 daddr, __be16 dport, int dif) 231 { 232 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, sport, 233 daddr, ntohs(dport), dif); 234 } 235 236 /* Socket demux engine toys. */ 237 /* What happens here is ugly; there's a pair of adjacent fields in 238 struct inet_sock; __be16 dport followed by __u16 num. We want to 239 search by pair, so we combine the keys into a single 32bit value 240 and compare with 32bit value read from &...->dport. Let's at least 241 make sure that it's not mixed with anything else... 242 On 64bit targets we combine comparisons with pair of adjacent __be32 243 fields in the same way. 244 */ 245 #ifdef __BIG_ENDIAN 246 #define INET_COMBINED_PORTS(__sport, __dport) \ 247 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport))) 248 #else /* __LITTLE_ENDIAN */ 249 #define INET_COMBINED_PORTS(__sport, __dport) \ 250 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport))) 251 #endif 252 253 #if (BITS_PER_LONG == 64) 254 #ifdef __BIG_ENDIAN 255 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 256 const __addrpair __name = (__force __addrpair) ( \ 257 (((__force __u64)(__be32)(__saddr)) << 32) | \ 258 ((__force __u64)(__be32)(__daddr))) 259 #else /* __LITTLE_ENDIAN */ 260 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 261 const __addrpair __name = (__force __addrpair) ( \ 262 (((__force __u64)(__be32)(__daddr)) << 32) | \ 263 ((__force __u64)(__be32)(__saddr))) 264 #endif /* __BIG_ENDIAN */ 265 #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif) \ 266 (((__sk)->sk_portpair == (__ports)) && \ 267 ((__sk)->sk_addrpair == (__cookie)) && \ 268 (!(__sk)->sk_bound_dev_if || \ 269 ((__sk)->sk_bound_dev_if == (__dif))) && \ 270 net_eq(sock_net(__sk), (__net))) 271 #else /* 32-bit arch */ 272 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 273 const int __name __deprecated __attribute__((unused)) 274 275 #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif) \ 276 (((__sk)->sk_portpair == (__ports)) && \ 277 ((__sk)->sk_daddr == (__saddr)) && \ 278 ((__sk)->sk_rcv_saddr == (__daddr)) && \ 279 (!(__sk)->sk_bound_dev_if || \ 280 ((__sk)->sk_bound_dev_if == (__dif))) && \ 281 net_eq(sock_net(__sk), (__net))) 282 #endif /* 64-bit arch */ 283 284 /* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need 285 * not check it for lookups anymore, thanks Alexey. -DaveM 286 */ 287 struct sock *__inet_lookup_established(struct net *net, 288 struct inet_hashinfo *hashinfo, 289 const __be32 saddr, const __be16 sport, 290 const __be32 daddr, const u16 hnum, 291 const int dif); 292 293 static inline struct sock * 294 inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo, 295 const __be32 saddr, const __be16 sport, 296 const __be32 daddr, const __be16 dport, 297 const int dif) 298 { 299 return __inet_lookup_established(net, hashinfo, saddr, sport, daddr, 300 ntohs(dport), dif); 301 } 302 303 static inline struct sock *__inet_lookup(struct net *net, 304 struct inet_hashinfo *hashinfo, 305 struct sk_buff *skb, int doff, 306 const __be32 saddr, const __be16 sport, 307 const __be32 daddr, const __be16 dport, 308 const int dif, 309 bool *refcounted) 310 { 311 u16 hnum = ntohs(dport); 312 struct sock *sk; 313 314 sk = __inet_lookup_established(net, hashinfo, saddr, sport, 315 daddr, hnum, dif); 316 *refcounted = true; 317 if (sk) 318 return sk; 319 *refcounted = false; 320 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, 321 sport, daddr, hnum, dif); 322 } 323 324 static inline struct sock *inet_lookup(struct net *net, 325 struct inet_hashinfo *hashinfo, 326 struct sk_buff *skb, int doff, 327 const __be32 saddr, const __be16 sport, 328 const __be32 daddr, const __be16 dport, 329 const int dif) 330 { 331 struct sock *sk; 332 bool refcounted; 333 334 sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr, 335 dport, dif, &refcounted); 336 337 if (sk && !refcounted && !atomic_inc_not_zero(&sk->sk_refcnt)) 338 sk = NULL; 339 return sk; 340 } 341 342 static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo, 343 struct sk_buff *skb, 344 int doff, 345 const __be16 sport, 346 const __be16 dport, 347 bool *refcounted) 348 { 349 struct sock *sk = skb_steal_sock(skb); 350 const struct iphdr *iph = ip_hdr(skb); 351 352 *refcounted = true; 353 if (sk) 354 return sk; 355 356 return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb, 357 doff, iph->saddr, sport, 358 iph->daddr, dport, inet_iif(skb), 359 refcounted); 360 } 361 362 u32 sk_ehashfn(const struct sock *sk); 363 u32 inet6_ehashfn(const struct net *net, 364 const struct in6_addr *laddr, const u16 lport, 365 const struct in6_addr *faddr, const __be16 fport); 366 367 static inline void sk_daddr_set(struct sock *sk, __be32 addr) 368 { 369 sk->sk_daddr = addr; /* alias of inet_daddr */ 370 #if IS_ENABLED(CONFIG_IPV6) 371 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_daddr); 372 #endif 373 } 374 375 static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr) 376 { 377 sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */ 378 #if IS_ENABLED(CONFIG_IPV6) 379 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_rcv_saddr); 380 #endif 381 } 382 383 int __inet_hash_connect(struct inet_timewait_death_row *death_row, 384 struct sock *sk, u32 port_offset, 385 int (*check_established)(struct inet_timewait_death_row *, 386 struct sock *, __u16, 387 struct inet_timewait_sock **)); 388 389 int inet_hash_connect(struct inet_timewait_death_row *death_row, 390 struct sock *sk); 391 #endif /* _INET_HASHTABLES_H */ 392