1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * INET An implementation of the TCP/IP protocol suite for the LINUX 4 * operating system. INET is implemented using the BSD Socket 5 * interface as the means of communication with the user level. 6 * 7 * Authors: Lotsa people, from code originally in tcp 8 */ 9 10 #ifndef _INET_HASHTABLES_H 11 #define _INET_HASHTABLES_H 12 13 14 #include <linux/interrupt.h> 15 #include <linux/ip.h> 16 #include <linux/ipv6.h> 17 #include <linux/list.h> 18 #include <linux/slab.h> 19 #include <linux/socket.h> 20 #include <linux/spinlock.h> 21 #include <linux/types.h> 22 #include <linux/wait.h> 23 24 #include <net/inet_connection_sock.h> 25 #include <net/inet_sock.h> 26 #include <net/sock.h> 27 #include <net/route.h> 28 #include <net/tcp_states.h> 29 #include <net/netns/hash.h> 30 31 #include <linux/refcount.h> 32 #include <asm/byteorder.h> 33 34 /* This is for all connections with a full identity, no wildcards. 35 * The 'e' prefix stands for Establish, but we really put all sockets 36 * but LISTEN ones. 37 */ 38 struct inet_ehash_bucket { 39 struct hlist_nulls_head chain; 40 }; 41 42 /* There are a few simple rules, which allow for local port reuse by 43 * an application. In essence: 44 * 45 * 1) Sockets bound to different interfaces may share a local port. 46 * Failing that, goto test 2. 47 * 2) If all sockets have sk->sk_reuse set, and none of them are in 48 * TCP_LISTEN state, the port may be shared. 49 * Failing that, goto test 3. 50 * 3) If all sockets are bound to a specific inet_sk(sk)->rcv_saddr local 51 * address, and none of them are the same, the port may be 52 * shared. 53 * Failing this, the port cannot be shared. 54 * 55 * The interesting point, is test #2. This is what an FTP server does 56 * all day. To optimize this case we use a specific flag bit defined 57 * below. As we add sockets to a bind bucket list, we perform a 58 * check of: (newsk->sk_reuse && (newsk->sk_state != TCP_LISTEN)) 59 * As long as all sockets added to a bind bucket pass this test, 60 * the flag bit will be set. 61 * The resulting situation is that tcp_v[46]_verify_bind() can just check 62 * for this flag bit, if it is set and the socket trying to bind has 63 * sk->sk_reuse set, we don't even have to walk the owners list at all, 64 * we return that it is ok to bind this socket to the requested local port. 65 * 66 * Sounds like a lot of work, but it is worth it. In a more naive 67 * implementation (ie. current FreeBSD etc.) the entire list of ports 68 * must be walked for each data port opened by an ftp server. Needless 69 * to say, this does not scale at all. With a couple thousand FTP 70 * users logged onto your box, isn't it nice to know that new data 71 * ports are created in O(1) time? I thought so. ;-) -DaveM 72 */ 73 #define FASTREUSEPORT_ANY 1 74 #define FASTREUSEPORT_STRICT 2 75 76 struct inet_bind_bucket { 77 possible_net_t ib_net; 78 int l3mdev; 79 unsigned short port; 80 signed char fastreuse; 81 signed char fastreuseport; 82 kuid_t fastuid; 83 #if IS_ENABLED(CONFIG_IPV6) 84 struct in6_addr fast_v6_rcv_saddr; 85 #endif 86 __be32 fast_rcv_saddr; 87 unsigned short fast_sk_family; 88 bool fast_ipv6_only; 89 struct hlist_node node; 90 struct hlist_head owners; 91 }; 92 93 static inline struct net *ib_net(struct inet_bind_bucket *ib) 94 { 95 return read_pnet(&ib->ib_net); 96 } 97 98 #define inet_bind_bucket_for_each(tb, head) \ 99 hlist_for_each_entry(tb, head, node) 100 101 struct inet_bind_hashbucket { 102 spinlock_t lock; 103 struct hlist_head chain; 104 }; 105 106 /* Sockets can be hashed in established or listening table. 107 * We must use different 'nulls' end-of-chain value for all hash buckets : 108 * A socket might transition from ESTABLISH to LISTEN state without 109 * RCU grace period. A lookup in ehash table needs to handle this case. 110 */ 111 #define LISTENING_NULLS_BASE (1U << 29) 112 struct inet_listen_hashbucket { 113 spinlock_t lock; 114 struct hlist_nulls_head nulls_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 kmem_cache *bind_bucket_cachep; 136 struct inet_bind_hashbucket *bhash; 137 unsigned int bhash_size; 138 139 /* The 2nd listener table hashed by local port and address */ 140 unsigned int lhash2_mask; 141 struct inet_listen_hashbucket *lhash2; 142 }; 143 144 static inline struct inet_listen_hashbucket * 145 inet_lhash2_bucket(struct inet_hashinfo *h, u32 hash) 146 { 147 return &h->lhash2[hash & h->lhash2_mask]; 148 } 149 150 static inline struct inet_ehash_bucket *inet_ehash_bucket( 151 struct inet_hashinfo *hashinfo, 152 unsigned int hash) 153 { 154 return &hashinfo->ehash[hash & hashinfo->ehash_mask]; 155 } 156 157 static inline spinlock_t *inet_ehash_lockp( 158 struct inet_hashinfo *hashinfo, 159 unsigned int hash) 160 { 161 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask]; 162 } 163 164 int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo); 165 166 static inline void inet_hashinfo2_free_mod(struct inet_hashinfo *h) 167 { 168 kfree(h->lhash2); 169 h->lhash2 = NULL; 170 } 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, int l3mdev); 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 /* Caller must disable local BH processing. */ 195 int __inet_inherit_port(const struct sock *sk, struct sock *child); 196 197 void inet_put_port(struct sock *sk); 198 199 void inet_hashinfo2_init(struct inet_hashinfo *h, const char *name, 200 unsigned long numentries, int scale, 201 unsigned long low_limit, 202 unsigned long high_limit); 203 int inet_hashinfo2_init_mod(struct inet_hashinfo *h); 204 205 bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk); 206 bool inet_ehash_nolisten(struct sock *sk, struct sock *osk, 207 bool *found_dup_sk); 208 int __inet_hash(struct sock *sk, struct sock *osk); 209 int inet_hash(struct sock *sk); 210 void inet_unhash(struct sock *sk); 211 212 struct sock *__inet_lookup_listener(struct net *net, 213 struct inet_hashinfo *hashinfo, 214 struct sk_buff *skb, int doff, 215 const __be32 saddr, const __be16 sport, 216 const __be32 daddr, 217 const unsigned short hnum, 218 const int dif, const int sdif); 219 220 static inline struct sock *inet_lookup_listener(struct net *net, 221 struct inet_hashinfo *hashinfo, 222 struct sk_buff *skb, int doff, 223 __be32 saddr, __be16 sport, 224 __be32 daddr, __be16 dport, int dif, int sdif) 225 { 226 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, sport, 227 daddr, ntohs(dport), dif, sdif); 228 } 229 230 /* Socket demux engine toys. */ 231 /* What happens here is ugly; there's a pair of adjacent fields in 232 struct inet_sock; __be16 dport followed by __u16 num. We want to 233 search by pair, so we combine the keys into a single 32bit value 234 and compare with 32bit value read from &...->dport. Let's at least 235 make sure that it's not mixed with anything else... 236 On 64bit targets we combine comparisons with pair of adjacent __be32 237 fields in the same way. 238 */ 239 #ifdef __BIG_ENDIAN 240 #define INET_COMBINED_PORTS(__sport, __dport) \ 241 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport))) 242 #else /* __LITTLE_ENDIAN */ 243 #define INET_COMBINED_PORTS(__sport, __dport) \ 244 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport))) 245 #endif 246 247 #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 */ 258 259 static inline bool inet_match(struct net *net, const struct sock *sk, 260 const __addrpair cookie, const __portpair ports, 261 int dif, int sdif) 262 { 263 if (!net_eq(sock_net(sk), net) || 264 sk->sk_portpair != ports || 265 sk->sk_addrpair != cookie) 266 return false; 267 268 /* READ_ONCE() paired with WRITE_ONCE() in sock_bindtoindex_locked() */ 269 return inet_sk_bound_dev_eq(net, READ_ONCE(sk->sk_bound_dev_if), dif, 270 sdif); 271 } 272 273 /* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need 274 * not check it for lookups anymore, thanks Alexey. -DaveM 275 */ 276 struct sock *__inet_lookup_established(struct net *net, 277 struct inet_hashinfo *hashinfo, 278 const __be32 saddr, const __be16 sport, 279 const __be32 daddr, const u16 hnum, 280 const int dif, const int sdif); 281 282 static inline struct sock * 283 inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo, 284 const __be32 saddr, const __be16 sport, 285 const __be32 daddr, const __be16 dport, 286 const int dif) 287 { 288 return __inet_lookup_established(net, hashinfo, saddr, sport, daddr, 289 ntohs(dport), dif, 0); 290 } 291 292 static inline struct sock *__inet_lookup(struct net *net, 293 struct inet_hashinfo *hashinfo, 294 struct sk_buff *skb, int doff, 295 const __be32 saddr, const __be16 sport, 296 const __be32 daddr, const __be16 dport, 297 const int dif, const int sdif, 298 bool *refcounted) 299 { 300 u16 hnum = ntohs(dport); 301 struct sock *sk; 302 303 sk = __inet_lookup_established(net, hashinfo, saddr, sport, 304 daddr, hnum, dif, sdif); 305 *refcounted = true; 306 if (sk) 307 return sk; 308 *refcounted = false; 309 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, 310 sport, daddr, hnum, dif, sdif); 311 } 312 313 static inline struct sock *inet_lookup(struct net *net, 314 struct inet_hashinfo *hashinfo, 315 struct sk_buff *skb, int doff, 316 const __be32 saddr, const __be16 sport, 317 const __be32 daddr, const __be16 dport, 318 const int dif) 319 { 320 struct sock *sk; 321 bool refcounted; 322 323 sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr, 324 dport, dif, 0, &refcounted); 325 326 if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt)) 327 sk = NULL; 328 return sk; 329 } 330 331 static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo, 332 struct sk_buff *skb, 333 int doff, 334 const __be16 sport, 335 const __be16 dport, 336 const int sdif, 337 bool *refcounted) 338 { 339 struct sock *sk = skb_steal_sock(skb, refcounted); 340 const struct iphdr *iph = ip_hdr(skb); 341 342 if (sk) 343 return sk; 344 345 return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb, 346 doff, iph->saddr, sport, 347 iph->daddr, dport, inet_iif(skb), sdif, 348 refcounted); 349 } 350 351 u32 inet6_ehashfn(const struct net *net, 352 const struct in6_addr *laddr, const u16 lport, 353 const struct in6_addr *faddr, const __be16 fport); 354 355 static inline void sk_daddr_set(struct sock *sk, __be32 addr) 356 { 357 sk->sk_daddr = addr; /* alias of inet_daddr */ 358 #if IS_ENABLED(CONFIG_IPV6) 359 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_daddr); 360 #endif 361 } 362 363 static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr) 364 { 365 sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */ 366 #if IS_ENABLED(CONFIG_IPV6) 367 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_rcv_saddr); 368 #endif 369 } 370 371 int __inet_hash_connect(struct inet_timewait_death_row *death_row, 372 struct sock *sk, u64 port_offset, 373 int (*check_established)(struct inet_timewait_death_row *, 374 struct sock *, __u16, 375 struct inet_timewait_sock **)); 376 377 int inet_hash_connect(struct inet_timewait_death_row *death_row, 378 struct sock *sk); 379 #endif /* _INET_HASHTABLES_H */ 380