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 static inline bool inet_sk_bound_dev_eq(struct net *net, int bound_dev_if, 179 int dif, int sdif) 180 { 181 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 182 return inet_bound_dev_eq(!!READ_ONCE(net->ipv4.sysctl_tcp_l3mdev_accept), 183 bound_dev_if, dif, sdif); 184 #else 185 return inet_bound_dev_eq(true, bound_dev_if, dif, sdif); 186 #endif 187 } 188 189 struct inet_bind_bucket * 190 inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net, 191 struct inet_bind_hashbucket *head, 192 const unsigned short snum, int l3mdev); 193 void inet_bind_bucket_destroy(struct kmem_cache *cachep, 194 struct inet_bind_bucket *tb); 195 196 static inline u32 inet_bhashfn(const struct net *net, const __u16 lport, 197 const u32 bhash_size) 198 { 199 return (lport + net_hash_mix(net)) & (bhash_size - 1); 200 } 201 202 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, 203 const unsigned short snum); 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_hashinfo2_init(struct inet_hashinfo *h, const char *name, 211 unsigned long numentries, int scale, 212 unsigned long low_limit, 213 unsigned long high_limit); 214 int inet_hashinfo2_init_mod(struct inet_hashinfo *h); 215 216 bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk); 217 bool inet_ehash_nolisten(struct sock *sk, struct sock *osk, 218 bool *found_dup_sk); 219 int __inet_hash(struct sock *sk, struct sock *osk); 220 int inet_hash(struct sock *sk); 221 void inet_unhash(struct sock *sk); 222 223 struct sock *__inet_lookup_listener(struct net *net, 224 struct inet_hashinfo *hashinfo, 225 struct sk_buff *skb, int doff, 226 const __be32 saddr, const __be16 sport, 227 const __be32 daddr, 228 const unsigned short hnum, 229 const int dif, const int sdif); 230 231 static inline struct sock *inet_lookup_listener(struct net *net, 232 struct inet_hashinfo *hashinfo, 233 struct sk_buff *skb, int doff, 234 __be32 saddr, __be16 sport, 235 __be32 daddr, __be16 dport, int dif, int sdif) 236 { 237 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, sport, 238 daddr, ntohs(dport), dif, sdif); 239 } 240 241 /* Socket demux engine toys. */ 242 /* What happens here is ugly; there's a pair of adjacent fields in 243 struct inet_sock; __be16 dport followed by __u16 num. We want to 244 search by pair, so we combine the keys into a single 32bit value 245 and compare with 32bit value read from &...->dport. Let's at least 246 make sure that it's not mixed with anything else... 247 On 64bit targets we combine comparisons with pair of adjacent __be32 248 fields in the same way. 249 */ 250 #ifdef __BIG_ENDIAN 251 #define INET_COMBINED_PORTS(__sport, __dport) \ 252 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport))) 253 #else /* __LITTLE_ENDIAN */ 254 #define INET_COMBINED_PORTS(__sport, __dport) \ 255 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport))) 256 #endif 257 258 #ifdef __BIG_ENDIAN 259 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 260 const __addrpair __name = (__force __addrpair) ( \ 261 (((__force __u64)(__be32)(__saddr)) << 32) | \ 262 ((__force __u64)(__be32)(__daddr))) 263 #else /* __LITTLE_ENDIAN */ 264 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 265 const __addrpair __name = (__force __addrpair) ( \ 266 (((__force __u64)(__be32)(__daddr)) << 32) | \ 267 ((__force __u64)(__be32)(__saddr))) 268 #endif /* __BIG_ENDIAN */ 269 270 static inline bool inet_match(struct net *net, const struct sock *sk, 271 const __addrpair cookie, const __portpair ports, 272 int dif, int sdif) 273 { 274 int bound_dev_if; 275 276 if (!net_eq(sock_net(sk), net) || 277 sk->sk_portpair != ports || 278 sk->sk_addrpair != cookie) 279 return false; 280 281 /* Paired with WRITE_ONCE() from sock_bindtoindex_locked() */ 282 bound_dev_if = READ_ONCE(sk->sk_bound_dev_if); 283 return bound_dev_if == dif || bound_dev_if == sdif; 284 } 285 286 /* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need 287 * not check it for lookups anymore, thanks Alexey. -DaveM 288 */ 289 struct sock *__inet_lookup_established(struct net *net, 290 struct inet_hashinfo *hashinfo, 291 const __be32 saddr, const __be16 sport, 292 const __be32 daddr, const u16 hnum, 293 const int dif, const int sdif); 294 295 static inline struct sock * 296 inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo, 297 const __be32 saddr, const __be16 sport, 298 const __be32 daddr, const __be16 dport, 299 const int dif) 300 { 301 return __inet_lookup_established(net, hashinfo, saddr, sport, daddr, 302 ntohs(dport), dif, 0); 303 } 304 305 static inline struct sock *__inet_lookup(struct net *net, 306 struct inet_hashinfo *hashinfo, 307 struct sk_buff *skb, int doff, 308 const __be32 saddr, const __be16 sport, 309 const __be32 daddr, const __be16 dport, 310 const int dif, const int sdif, 311 bool *refcounted) 312 { 313 u16 hnum = ntohs(dport); 314 struct sock *sk; 315 316 sk = __inet_lookup_established(net, hashinfo, saddr, sport, 317 daddr, hnum, dif, sdif); 318 *refcounted = true; 319 if (sk) 320 return sk; 321 *refcounted = false; 322 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, 323 sport, daddr, hnum, dif, sdif); 324 } 325 326 static inline struct sock *inet_lookup(struct net *net, 327 struct inet_hashinfo *hashinfo, 328 struct sk_buff *skb, int doff, 329 const __be32 saddr, const __be16 sport, 330 const __be32 daddr, const __be16 dport, 331 const int dif) 332 { 333 struct sock *sk; 334 bool refcounted; 335 336 sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr, 337 dport, dif, 0, &refcounted); 338 339 if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt)) 340 sk = NULL; 341 return sk; 342 } 343 344 static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo, 345 struct sk_buff *skb, 346 int doff, 347 const __be16 sport, 348 const __be16 dport, 349 const int sdif, 350 bool *refcounted) 351 { 352 struct sock *sk = skb_steal_sock(skb, refcounted); 353 const struct iphdr *iph = ip_hdr(skb); 354 355 if (sk) 356 return sk; 357 358 return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb, 359 doff, iph->saddr, sport, 360 iph->daddr, dport, inet_iif(skb), sdif, 361 refcounted); 362 } 363 364 u32 inet6_ehashfn(const struct net *net, 365 const struct in6_addr *laddr, const u16 lport, 366 const struct in6_addr *faddr, const __be16 fport); 367 368 static inline void sk_daddr_set(struct sock *sk, __be32 addr) 369 { 370 sk->sk_daddr = addr; /* alias of inet_daddr */ 371 #if IS_ENABLED(CONFIG_IPV6) 372 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_daddr); 373 #endif 374 } 375 376 static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr) 377 { 378 sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */ 379 #if IS_ENABLED(CONFIG_IPV6) 380 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_rcv_saddr); 381 #endif 382 } 383 384 int __inet_hash_connect(struct inet_timewait_death_row *death_row, 385 struct sock *sk, u64 port_offset, 386 int (*check_established)(struct inet_timewait_death_row *, 387 struct sock *, __u16, 388 struct inet_timewait_sock **)); 389 390 int inet_hash_connect(struct inet_timewait_death_row *death_row, 391 struct sock *sk); 392 #endif /* _INET_HASHTABLES_H */ 393