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 * Generic INET transport hashtables 7 * 8 * Authors: Lotsa people, from code originally in tcp 9 * 10 * This program is free software; you can redistribute it and/or 11 * modify it under the terms of the GNU General Public License 12 * as published by the Free Software Foundation; either version 13 * 2 of the License, or (at your option) any later version. 14 */ 15 16 #include <linux/module.h> 17 #include <linux/random.h> 18 #include <linux/sched.h> 19 #include <linux/slab.h> 20 #include <linux/wait.h> 21 22 #include <net/inet_connection_sock.h> 23 #include <net/inet_hashtables.h> 24 #include <net/ip.h> 25 26 /* 27 * Allocate and initialize a new local port bind bucket. 28 * The bindhash mutex for snum's hash chain must be held here. 29 */ 30 struct inet_bind_bucket *inet_bind_bucket_create(kmem_cache_t *cachep, 31 struct inet_bind_hashbucket *head, 32 const unsigned short snum) 33 { 34 struct inet_bind_bucket *tb = kmem_cache_alloc(cachep, SLAB_ATOMIC); 35 36 if (tb != NULL) { 37 tb->port = snum; 38 tb->fastreuse = 0; 39 INIT_HLIST_HEAD(&tb->owners); 40 hlist_add_head(&tb->node, &head->chain); 41 } 42 return tb; 43 } 44 45 /* 46 * Caller must hold hashbucket lock for this tb with local BH disabled 47 */ 48 void inet_bind_bucket_destroy(kmem_cache_t *cachep, struct inet_bind_bucket *tb) 49 { 50 if (hlist_empty(&tb->owners)) { 51 __hlist_del(&tb->node); 52 kmem_cache_free(cachep, tb); 53 } 54 } 55 56 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, 57 const unsigned short snum) 58 { 59 inet_sk(sk)->num = snum; 60 sk_add_bind_node(sk, &tb->owners); 61 inet_csk(sk)->icsk_bind_hash = tb; 62 } 63 64 /* 65 * Get rid of any references to a local port held by the given sock. 66 */ 67 static void __inet_put_port(struct inet_hashinfo *hashinfo, struct sock *sk) 68 { 69 const int bhash = inet_bhashfn(inet_sk(sk)->num, hashinfo->bhash_size); 70 struct inet_bind_hashbucket *head = &hashinfo->bhash[bhash]; 71 struct inet_bind_bucket *tb; 72 73 spin_lock(&head->lock); 74 tb = inet_csk(sk)->icsk_bind_hash; 75 __sk_del_bind_node(sk); 76 inet_csk(sk)->icsk_bind_hash = NULL; 77 inet_sk(sk)->num = 0; 78 inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb); 79 spin_unlock(&head->lock); 80 } 81 82 void inet_put_port(struct inet_hashinfo *hashinfo, struct sock *sk) 83 { 84 local_bh_disable(); 85 __inet_put_port(hashinfo, sk); 86 local_bh_enable(); 87 } 88 89 EXPORT_SYMBOL(inet_put_port); 90 91 /* 92 * This lock without WQ_FLAG_EXCLUSIVE is good on UP and it can be very bad on SMP. 93 * Look, when several writers sleep and reader wakes them up, all but one 94 * immediately hit write lock and grab all the cpus. Exclusive sleep solves 95 * this, _but_ remember, it adds useless work on UP machines (wake up each 96 * exclusive lock release). It should be ifdefed really. 97 */ 98 void inet_listen_wlock(struct inet_hashinfo *hashinfo) 99 { 100 write_lock(&hashinfo->lhash_lock); 101 102 if (atomic_read(&hashinfo->lhash_users)) { 103 DEFINE_WAIT(wait); 104 105 for (;;) { 106 prepare_to_wait_exclusive(&hashinfo->lhash_wait, 107 &wait, TASK_UNINTERRUPTIBLE); 108 if (!atomic_read(&hashinfo->lhash_users)) 109 break; 110 write_unlock_bh(&hashinfo->lhash_lock); 111 schedule(); 112 write_lock_bh(&hashinfo->lhash_lock); 113 } 114 115 finish_wait(&hashinfo->lhash_wait, &wait); 116 } 117 } 118 119 EXPORT_SYMBOL(inet_listen_wlock); 120 121 /* 122 * Don't inline this cruft. Here are some nice properties to exploit here. The 123 * BSD API does not allow a listening sock to specify the remote port nor the 124 * remote address for the connection. So always assume those are both 125 * wildcarded during the search since they can never be otherwise. 126 */ 127 struct sock *__inet_lookup_listener(const struct hlist_head *head, const u32 daddr, 128 const unsigned short hnum, const int dif) 129 { 130 struct sock *result = NULL, *sk; 131 const struct hlist_node *node; 132 int hiscore = -1; 133 134 sk_for_each(sk, node, head) { 135 const struct inet_sock *inet = inet_sk(sk); 136 137 if (inet->num == hnum && !ipv6_only_sock(sk)) { 138 const __u32 rcv_saddr = inet->rcv_saddr; 139 int score = sk->sk_family == PF_INET ? 1 : 0; 140 141 if (rcv_saddr) { 142 if (rcv_saddr != daddr) 143 continue; 144 score += 2; 145 } 146 if (sk->sk_bound_dev_if) { 147 if (sk->sk_bound_dev_if != dif) 148 continue; 149 score += 2; 150 } 151 if (score == 5) 152 return sk; 153 if (score > hiscore) { 154 hiscore = score; 155 result = sk; 156 } 157 } 158 } 159 return result; 160 } 161 162 EXPORT_SYMBOL_GPL(__inet_lookup_listener); 163 164 /* called with local bh disabled */ 165 static int __inet_check_established(struct inet_timewait_death_row *death_row, 166 struct sock *sk, __u16 lport, 167 struct inet_timewait_sock **twp) 168 { 169 struct inet_hashinfo *hinfo = death_row->hashinfo; 170 struct inet_sock *inet = inet_sk(sk); 171 u32 daddr = inet->rcv_saddr; 172 u32 saddr = inet->daddr; 173 int dif = sk->sk_bound_dev_if; 174 INET_ADDR_COOKIE(acookie, saddr, daddr) 175 const __u32 ports = INET_COMBINED_PORTS(inet->dport, lport); 176 unsigned int hash = inet_ehashfn(daddr, lport, saddr, inet->dport); 177 struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash); 178 struct sock *sk2; 179 const struct hlist_node *node; 180 struct inet_timewait_sock *tw; 181 182 prefetch(head->chain.first); 183 write_lock(&head->lock); 184 185 /* Check TIME-WAIT sockets first. */ 186 sk_for_each(sk2, node, &(head + hinfo->ehash_size)->chain) { 187 tw = inet_twsk(sk2); 188 189 if (INET_TW_MATCH(sk2, hash, acookie, saddr, daddr, ports, dif)) { 190 if (twsk_unique(sk, sk2, twp)) 191 goto unique; 192 else 193 goto not_unique; 194 } 195 } 196 tw = NULL; 197 198 /* And established part... */ 199 sk_for_each(sk2, node, &head->chain) { 200 if (INET_MATCH(sk2, hash, acookie, saddr, daddr, ports, dif)) 201 goto not_unique; 202 } 203 204 unique: 205 /* Must record num and sport now. Otherwise we will see 206 * in hash table socket with a funny identity. */ 207 inet->num = lport; 208 inet->sport = htons(lport); 209 sk->sk_hash = hash; 210 BUG_TRAP(sk_unhashed(sk)); 211 __sk_add_node(sk, &head->chain); 212 sock_prot_inc_use(sk->sk_prot); 213 write_unlock(&head->lock); 214 215 if (twp) { 216 *twp = tw; 217 NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED); 218 } else if (tw) { 219 /* Silly. Should hash-dance instead... */ 220 inet_twsk_deschedule(tw, death_row); 221 NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED); 222 223 inet_twsk_put(tw); 224 } 225 226 return 0; 227 228 not_unique: 229 write_unlock(&head->lock); 230 return -EADDRNOTAVAIL; 231 } 232 233 static inline u32 inet_sk_port_offset(const struct sock *sk) 234 { 235 const struct inet_sock *inet = inet_sk(sk); 236 return secure_ipv4_port_ephemeral(inet->rcv_saddr, inet->daddr, 237 inet->dport); 238 } 239 240 /* 241 * Bind a port for a connect operation and hash it. 242 */ 243 int inet_hash_connect(struct inet_timewait_death_row *death_row, 244 struct sock *sk) 245 { 246 struct inet_hashinfo *hinfo = death_row->hashinfo; 247 const unsigned short snum = inet_sk(sk)->num; 248 struct inet_bind_hashbucket *head; 249 struct inet_bind_bucket *tb; 250 int ret; 251 252 if (!snum) { 253 int low = sysctl_local_port_range[0]; 254 int high = sysctl_local_port_range[1]; 255 int range = high - low; 256 int i; 257 int port; 258 static u32 hint; 259 u32 offset = hint + inet_sk_port_offset(sk); 260 struct hlist_node *node; 261 struct inet_timewait_sock *tw = NULL; 262 263 local_bh_disable(); 264 for (i = 1; i <= range; i++) { 265 port = low + (i + offset) % range; 266 head = &hinfo->bhash[inet_bhashfn(port, hinfo->bhash_size)]; 267 spin_lock(&head->lock); 268 269 /* Does not bother with rcv_saddr checks, 270 * because the established check is already 271 * unique enough. 272 */ 273 inet_bind_bucket_for_each(tb, node, &head->chain) { 274 if (tb->port == port) { 275 BUG_TRAP(!hlist_empty(&tb->owners)); 276 if (tb->fastreuse >= 0) 277 goto next_port; 278 if (!__inet_check_established(death_row, 279 sk, port, 280 &tw)) 281 goto ok; 282 goto next_port; 283 } 284 } 285 286 tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep, head, port); 287 if (!tb) { 288 spin_unlock(&head->lock); 289 break; 290 } 291 tb->fastreuse = -1; 292 goto ok; 293 294 next_port: 295 spin_unlock(&head->lock); 296 } 297 local_bh_enable(); 298 299 return -EADDRNOTAVAIL; 300 301 ok: 302 hint += i; 303 304 /* Head lock still held and bh's disabled */ 305 inet_bind_hash(sk, tb, port); 306 if (sk_unhashed(sk)) { 307 inet_sk(sk)->sport = htons(port); 308 __inet_hash(hinfo, sk, 0); 309 } 310 spin_unlock(&head->lock); 311 312 if (tw) { 313 inet_twsk_deschedule(tw, death_row); 314 inet_twsk_put(tw); 315 } 316 317 ret = 0; 318 goto out; 319 } 320 321 head = &hinfo->bhash[inet_bhashfn(snum, hinfo->bhash_size)]; 322 tb = inet_csk(sk)->icsk_bind_hash; 323 spin_lock_bh(&head->lock); 324 if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) { 325 __inet_hash(hinfo, sk, 0); 326 spin_unlock_bh(&head->lock); 327 return 0; 328 } else { 329 spin_unlock(&head->lock); 330 /* No definite answer... Walk to established hash table */ 331 ret = __inet_check_established(death_row, sk, snum, NULL); 332 out: 333 local_bh_enable(); 334 return ret; 335 } 336 } 337 338 EXPORT_SYMBOL_GPL(inet_hash_connect); 339