Commit | Line | Data |
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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
e48c414e ACM |
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 | * Generic TIME_WAIT sockets functions | |
8 | * | |
9 | * From code orinally in TCP | |
10 | */ | |
11 | ||
172589cc | 12 | #include <linux/kernel.h> |
5a0e3ad6 | 13 | #include <linux/slab.h> |
3a9a231d | 14 | #include <linux/module.h> |
e48c414e ACM |
15 | #include <net/inet_hashtables.h> |
16 | #include <net/inet_timewait_sock.h> | |
696ab2d3 | 17 | #include <net/ip.h> |
e48c414e | 18 | |
13475a30 | 19 | |
2a8875e7 ED |
20 | /** |
21 | * inet_twsk_bind_unhash - unhash a timewait socket from bind hash | |
22 | * @tw: timewait socket | |
23 | * @hashinfo: hashinfo pointer | |
24 | * | |
25 | * unhash a timewait socket from bind hash, if hashed. | |
26 | * bind hash lock must be held by caller. | |
27 | * Returns 1 if caller should call inet_twsk_put() after lock release. | |
3cdaedae | 28 | */ |
fc01538f | 29 | void inet_twsk_bind_unhash(struct inet_timewait_sock *tw, |
3cdaedae ED |
30 | struct inet_hashinfo *hashinfo) |
31 | { | |
32 | struct inet_bind_bucket *tb = tw->tw_tb; | |
33 | ||
34 | if (!tb) | |
fc01538f | 35 | return; |
3cdaedae ED |
36 | |
37 | __hlist_del(&tw->tw_bind_node); | |
38 | tw->tw_tb = NULL; | |
39 | inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb); | |
fc01538f | 40 | __sock_put((struct sock *)tw); |
3cdaedae ED |
41 | } |
42 | ||
e48c414e | 43 | /* Must be called with locally disabled BHs. */ |
789f558c | 44 | static void inet_twsk_kill(struct inet_timewait_sock *tw) |
e48c414e | 45 | { |
789f558c | 46 | struct inet_hashinfo *hashinfo = tw->tw_dr->hashinfo; |
9db66bdc | 47 | spinlock_t *lock = inet_ehash_lockp(hashinfo, tw->tw_hash); |
fc01538f | 48 | struct inet_bind_hashbucket *bhead; |
e48c414e | 49 | |
9db66bdc | 50 | spin_lock(lock); |
fc01538f | 51 | sk_nulls_del_node_init_rcu((struct sock *)tw); |
9db66bdc | 52 | spin_unlock(lock); |
e48c414e ACM |
53 | |
54 | /* Disassociate with bind bucket. */ | |
04c494e6 ED |
55 | bhead = &hashinfo->bhash[inet_bhashfn(twsk_net(tw), tw->tw_num, |
56 | hashinfo->bhash_size)]; | |
3cdaedae | 57 | |
e48c414e | 58 | spin_lock(&bhead->lock); |
fc01538f | 59 | inet_twsk_bind_unhash(tw, hashinfo); |
e48c414e | 60 | spin_unlock(&bhead->lock); |
3cdaedae | 61 | |
fbb82952 ED |
62 | if (refcount_dec_and_test(&tw->tw_dr->tw_refcount)) |
63 | kfree(tw->tw_dr); | |
64 | ||
789f558c | 65 | inet_twsk_put(tw); |
e48c414e ACM |
66 | } |
67 | ||
05dbc7b5 | 68 | void inet_twsk_free(struct inet_timewait_sock *tw) |
7054fb93 | 69 | { |
4dbc8ef7 ACM |
70 | struct module *owner = tw->tw_prot->owner; |
71 | twsk_destructor((struct sock *)tw); | |
7054fb93 | 72 | #ifdef SOCK_REFCNT_DEBUG |
4dbc8ef7 | 73 | pr_debug("%s timewait_sock %p released\n", tw->tw_prot->name, tw); |
7054fb93 | 74 | #endif |
4dbc8ef7 ACM |
75 | kmem_cache_free(tw->tw_prot->twsk_prot->twsk_slab, tw); |
76 | module_put(owner); | |
77 | } | |
78 | ||
79 | void inet_twsk_put(struct inet_timewait_sock *tw) | |
80 | { | |
41c6d650 | 81 | if (refcount_dec_and_test(&tw->tw_refcnt)) |
4dbc8ef7 | 82 | inet_twsk_free(tw); |
7054fb93 PE |
83 | } |
84 | EXPORT_SYMBOL_GPL(inet_twsk_put); | |
85 | ||
05dbc7b5 ED |
86 | static void inet_twsk_add_node_rcu(struct inet_timewait_sock *tw, |
87 | struct hlist_nulls_head *list) | |
88 | { | |
89 | hlist_nulls_add_head_rcu(&tw->tw_node, list); | |
90 | } | |
91 | ||
92 | static void inet_twsk_add_bind_node(struct inet_timewait_sock *tw, | |
93 | struct hlist_head *list) | |
94 | { | |
95 | hlist_add_head(&tw->tw_bind_node, list); | |
96 | } | |
97 | ||
e48c414e | 98 | /* |
e599ea14 | 99 | * Enter the time wait state. This is called with locally disabled BH. |
e48c414e ACM |
100 | * Essentially we whip up a timewait bucket, copy the relevant info into it |
101 | * from the SK, and mess with hash chains and list linkage. | |
102 | */ | |
ec94c269 | 103 | void inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk, |
e48c414e ACM |
104 | struct inet_hashinfo *hashinfo) |
105 | { | |
106 | const struct inet_sock *inet = inet_sk(sk); | |
463c84b9 | 107 | const struct inet_connection_sock *icsk = inet_csk(sk); |
81c3d547 | 108 | struct inet_ehash_bucket *ehead = inet_ehash_bucket(hashinfo, sk->sk_hash); |
9db66bdc | 109 | spinlock_t *lock = inet_ehash_lockp(hashinfo, sk->sk_hash); |
e48c414e ACM |
110 | struct inet_bind_hashbucket *bhead; |
111 | /* Step 1: Put TW into bind hash. Original socket stays there too. | |
112 | Note, that any socket with inet->num != 0 MUST be bound in | |
113 | binding cache, even if it is closed. | |
114 | */ | |
04c494e6 ED |
115 | bhead = &hashinfo->bhash[inet_bhashfn(twsk_net(tw), inet->inet_num, |
116 | hashinfo->bhash_size)]; | |
e599ea14 | 117 | spin_lock(&bhead->lock); |
463c84b9 | 118 | tw->tw_tb = icsk->icsk_bind_hash; |
547b792c | 119 | WARN_ON(!icsk->icsk_bind_hash); |
e48c414e ACM |
120 | inet_twsk_add_bind_node(tw, &tw->tw_tb->owners); |
121 | spin_unlock(&bhead->lock); | |
122 | ||
9db66bdc | 123 | spin_lock(lock); |
e48c414e | 124 | |
05dbc7b5 | 125 | inet_twsk_add_node_rcu(tw, &ehead->chain); |
3ab5aee7 | 126 | |
05dbc7b5 | 127 | /* Step 3: Remove SK from hash chain */ |
3ab5aee7 ED |
128 | if (__sk_nulls_del_node_init_rcu(sk)) |
129 | sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1); | |
e48c414e | 130 | |
e599ea14 | 131 | spin_unlock(lock); |
ec94c269 ED |
132 | |
133 | /* tw_refcnt is set to 3 because we have : | |
134 | * - one reference for bhash chain. | |
135 | * - one reference for ehash chain. | |
136 | * - one reference for timer. | |
137 | * We can use atomic_set() because prior spin_lock()/spin_unlock() | |
138 | * committed into memory all tw fields. | |
139 | * Also note that after this point, we lost our implicit reference | |
140 | * so we are not allowed to use tw anymore. | |
141 | */ | |
142 | refcount_set(&tw->tw_refcnt, 3); | |
e48c414e | 143 | } |
ec94c269 | 144 | EXPORT_SYMBOL_GPL(inet_twsk_hashdance); |
696ab2d3 | 145 | |
1ab791dc | 146 | static void tw_timer_handler(struct timer_list *t) |
c676270b | 147 | { |
1ab791dc | 148 | struct inet_timewait_sock *tw = from_timer(tw, t, tw_timer); |
789f558c | 149 | |
789f558c ED |
150 | inet_twsk_kill(tw); |
151 | } | |
152 | ||
153 | struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk, | |
154 | struct inet_timewait_death_row *dr, | |
155 | const int state) | |
156 | { | |
157 | struct inet_timewait_sock *tw; | |
158 | ||
6f605b57 KI |
159 | if (refcount_read(&dr->tw_refcount) - 1 >= |
160 | READ_ONCE(dr->sysctl_max_tw_buckets)) | |
789f558c ED |
161 | return NULL; |
162 | ||
163 | tw = kmem_cache_alloc(sk->sk_prot_creator->twsk_prot->twsk_slab, | |
164 | GFP_ATOMIC); | |
00db4124 | 165 | if (tw) { |
c676270b ACM |
166 | const struct inet_sock *inet = inet_sk(sk); |
167 | ||
789f558c | 168 | tw->tw_dr = dr; |
c676270b | 169 | /* Give us an identity. */ |
c720c7e8 ED |
170 | tw->tw_daddr = inet->inet_daddr; |
171 | tw->tw_rcv_saddr = inet->inet_rcv_saddr; | |
c676270b | 172 | tw->tw_bound_dev_if = sk->sk_bound_dev_if; |
66b13d99 | 173 | tw->tw_tos = inet->tos; |
c720c7e8 | 174 | tw->tw_num = inet->inet_num; |
c676270b ACM |
175 | tw->tw_state = TCP_TIME_WAIT; |
176 | tw->tw_substate = state; | |
c720c7e8 ED |
177 | tw->tw_sport = inet->inet_sport; |
178 | tw->tw_dport = inet->inet_dport; | |
c676270b ACM |
179 | tw->tw_family = sk->sk_family; |
180 | tw->tw_reuse = sk->sk_reuse; | |
3099a529 | 181 | tw->tw_reuseport = sk->sk_reuseport; |
81c3d547 | 182 | tw->tw_hash = sk->sk_hash; |
c676270b | 183 | tw->tw_ipv6only = 0; |
f5715aea | 184 | tw->tw_transparent = inet->transparent; |
c676270b | 185 | tw->tw_prot = sk->sk_prot_creator; |
33cf7c90 | 186 | atomic64_set(&tw->tw_cookie, atomic64_read(&sk->sk_cookie)); |
efd7ef1c | 187 | twsk_net_set(tw, sock_net(sk)); |
1ab791dc | 188 | timer_setup(&tw->tw_timer, tw_timer_handler, TIMER_PINNED); |
47e1c323 ED |
189 | /* |
190 | * Because we use RCU lookups, we should not set tw_refcnt | |
191 | * to a non null value before everything is setup for this | |
192 | * timewait socket. | |
193 | */ | |
41c6d650 | 194 | refcount_set(&tw->tw_refcnt, 0); |
789f558c | 195 | |
eeb2b856 | 196 | __module_get(tw->tw_prot->owner); |
c676270b ACM |
197 | } |
198 | ||
199 | return tw; | |
200 | } | |
696ab2d3 ACM |
201 | EXPORT_SYMBOL_GPL(inet_twsk_alloc); |
202 | ||
696ab2d3 ACM |
203 | /* These are always called from BH context. See callers in |
204 | * tcp_input.c to verify this. | |
205 | */ | |
206 | ||
dbe7faa4 ED |
207 | /* This is for handling early-kills of TIME_WAIT sockets. |
208 | * Warning : consume reference. | |
209 | * Caller should not access tw anymore. | |
210 | */ | |
211 | void inet_twsk_deschedule_put(struct inet_timewait_sock *tw) | |
696ab2d3 | 212 | { |
789f558c ED |
213 | if (del_timer_sync(&tw->tw_timer)) |
214 | inet_twsk_kill(tw); | |
dbe7faa4 | 215 | inet_twsk_put(tw); |
696ab2d3 | 216 | } |
dbe7faa4 | 217 | EXPORT_SYMBOL(inet_twsk_deschedule_put); |
696ab2d3 | 218 | |
ed2e9239 | 219 | void __inet_twsk_schedule(struct inet_timewait_sock *tw, int timeo, bool rearm) |
696ab2d3 | 220 | { |
696ab2d3 ACM |
221 | /* timeout := RTO * 3.5 |
222 | * | |
223 | * 3.5 = 1+2+0.5 to wait for two retransmits. | |
224 | * | |
225 | * RATIONALE: if FIN arrived and we entered TIME-WAIT state, | |
226 | * our ACK acking that FIN can be lost. If N subsequent retransmitted | |
227 | * FINs (or previous seqments) are lost (probability of such event | |
228 | * is p^(N+1), where p is probability to lose single packet and | |
229 | * time to detect the loss is about RTO*(2^N - 1) with exponential | |
230 | * backoff). Normal timewait length is calculated so, that we | |
231 | * waited at least for one retransmitted FIN (maximal RTO is 120sec). | |
232 | * [ BTW Linux. following BSD, violates this requirement waiting | |
233 | * only for 60sec, we should wait at least for 240 secs. | |
234 | * Well, 240 consumes too much of resources 8) | |
235 | * ] | |
236 | * This interval is not reduced to catch old duplicate and | |
237 | * responces to our wandering segments living for two MSLs. | |
238 | * However, if we use PAWS to detect | |
239 | * old duplicates, we can reduce the interval to bounds required | |
240 | * by RTO, rather than MSL. So, if peer understands PAWS, we | |
241 | * kill tw bucket after 3.5*RTO (it is important that this number | |
242 | * is greater than TS tick!) and detect old duplicates with help | |
243 | * of PAWS. | |
244 | */ | |
696ab2d3 | 245 | |
ed2e9239 | 246 | if (!rearm) { |
27dd35e0 ED |
247 | bool kill = timeo <= 4*HZ; |
248 | ||
249 | __NET_INC_STATS(twsk_net(tw), kill ? LINUX_MIB_TIMEWAITKILLED : | |
250 | LINUX_MIB_TIMEWAITED); | |
f3438bc7 | 251 | BUG_ON(mod_timer(&tw->tw_timer, jiffies + timeo)); |
fbb82952 | 252 | refcount_inc(&tw->tw_dr->tw_refcount); |
ed2e9239 ED |
253 | } else { |
254 | mod_timer_pending(&tw->tw_timer, jiffies + timeo); | |
696ab2d3 | 255 | } |
696ab2d3 | 256 | } |
ed2e9239 | 257 | EXPORT_SYMBOL_GPL(__inet_twsk_schedule); |
04c494e6 ED |
258 | |
259 | void inet_twsk_purge(struct inet_hashinfo *hashinfo, int family) | |
260 | { | |
261 | struct inet_timewait_sock *tw; | |
262 | struct sock *sk; | |
263 | struct hlist_nulls_node *node; | |
264 | unsigned int slot; | |
265 | ||
266 | for (slot = 0; slot <= hashinfo->ehash_mask; slot++) { | |
267 | struct inet_ehash_bucket *head = &hashinfo->ehash[slot]; | |
268 | restart_rcu: | |
269 | cond_resched(); | |
270 | rcu_read_lock(); | |
271 | restart: | |
272 | sk_nulls_for_each_rcu(sk, node, &head->chain) { | |
273 | if (sk->sk_state != TCP_TIME_WAIT) | |
274 | continue; | |
275 | tw = inet_twsk(sk); | |
276 | if ((tw->tw_family != family) || | |
277 | refcount_read(&twsk_net(tw)->ns.count)) | |
278 | continue; | |
279 | ||
280 | if (unlikely(!refcount_inc_not_zero(&tw->tw_refcnt))) | |
281 | continue; | |
282 | ||
283 | if (unlikely((tw->tw_family != family) || | |
284 | refcount_read(&twsk_net(tw)->ns.count))) { | |
285 | inet_twsk_put(tw); | |
286 | goto restart; | |
287 | } | |
288 | ||
289 | rcu_read_unlock(); | |
290 | local_bh_disable(); | |
291 | inet_twsk_deschedule_put(tw); | |
292 | local_bh_enable(); | |
293 | goto restart_rcu; | |
294 | } | |
295 | /* If the nulls value we got at the end of this lookup is | |
296 | * not the expected one, we must restart lookup. | |
297 | * We probably met an item that was moved to another chain. | |
298 | */ | |
299 | if (get_nulls_value(node) != slot) | |
300 | goto restart; | |
301 | rcu_read_unlock(); | |
302 | } | |
303 | } | |
304 | EXPORT_SYMBOL_GPL(inet_twsk_purge); |