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  *		Definitions for a generic INET TIMEWAIT sock
7  *
8  *		From code originally in net/tcp.h
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 #ifndef _INET_TIMEWAIT_SOCK_
16 #define _INET_TIMEWAIT_SOCK_
17 
18 
19 #include <linux/kmemcheck.h>
20 #include <linux/list.h>
21 #include <linux/module.h>
22 #include <linux/timer.h>
23 #include <linux/types.h>
24 #include <linux/workqueue.h>
25 
26 #include <net/inet_sock.h>
27 #include <net/sock.h>
28 #include <net/tcp_states.h>
29 #include <net/timewait_sock.h>
30 
31 #include <asm/atomic.h>
32 
33 struct inet_hashinfo;
34 
35 #define INET_TWDR_RECYCLE_SLOTS_LOG	5
36 #define INET_TWDR_RECYCLE_SLOTS		(1 << INET_TWDR_RECYCLE_SLOTS_LOG)
37 
38 /*
39  * If time > 4sec, it is "slow" path, no recycling is required,
40  * so that we select tick to get range about 4 seconds.
41  */
42 #if HZ <= 16 || HZ > 4096
43 # error Unsupported: HZ <= 16 or HZ > 4096
44 #elif HZ <= 32
45 # define INET_TWDR_RECYCLE_TICK (5 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
46 #elif HZ <= 64
47 # define INET_TWDR_RECYCLE_TICK (6 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
48 #elif HZ <= 128
49 # define INET_TWDR_RECYCLE_TICK (7 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
50 #elif HZ <= 256
51 # define INET_TWDR_RECYCLE_TICK (8 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
52 #elif HZ <= 512
53 # define INET_TWDR_RECYCLE_TICK (9 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
54 #elif HZ <= 1024
55 # define INET_TWDR_RECYCLE_TICK (10 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
56 #elif HZ <= 2048
57 # define INET_TWDR_RECYCLE_TICK (11 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
58 #else
59 # define INET_TWDR_RECYCLE_TICK (12 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
60 #endif
61 
62 /* TIME_WAIT reaping mechanism. */
63 #define INET_TWDR_TWKILL_SLOTS	8 /* Please keep this a power of 2. */
64 
65 #define INET_TWDR_TWKILL_QUOTA 100
66 
67 struct inet_timewait_death_row {
68 	/* Short-time timewait calendar */
69 	int			twcal_hand;
70 	unsigned long		twcal_jiffie;
71 	struct timer_list	twcal_timer;
72 	struct hlist_head	twcal_row[INET_TWDR_RECYCLE_SLOTS];
73 
74 	spinlock_t		death_lock;
75 	int			tw_count;
76 	int			period;
77 	u32			thread_slots;
78 	struct work_struct	twkill_work;
79 	struct timer_list	tw_timer;
80 	int			slot;
81 	struct hlist_head	cells[INET_TWDR_TWKILL_SLOTS];
82 	struct inet_hashinfo 	*hashinfo;
83 	int			sysctl_tw_recycle;
84 	int			sysctl_max_tw_buckets;
85 };
86 
87 extern void inet_twdr_hangman(unsigned long data);
88 extern void inet_twdr_twkill_work(struct work_struct *work);
89 extern void inet_twdr_twcal_tick(unsigned long data);
90 
91 #if (BITS_PER_LONG == 64)
92 #define INET_TIMEWAIT_ADDRCMP_ALIGN_BYTES 8
93 #else
94 #define INET_TIMEWAIT_ADDRCMP_ALIGN_BYTES 4
95 #endif
96 
97 struct inet_bind_bucket;
98 
99 /*
100  * This is a TIME_WAIT sock. It works around the memory consumption
101  * problems of sockets in such a state on heavily loaded servers, but
102  * without violating the protocol specification.
103  */
104 struct inet_timewait_sock {
105 	/*
106 	 * Now struct sock also uses sock_common, so please just
107 	 * don't add nothing before this first member (__tw_common) --acme
108 	 */
109 	struct sock_common	__tw_common;
110 #define tw_family		__tw_common.skc_family
111 #define tw_state		__tw_common.skc_state
112 #define tw_reuse		__tw_common.skc_reuse
113 #define tw_bound_dev_if		__tw_common.skc_bound_dev_if
114 #define tw_node			__tw_common.skc_nulls_node
115 #define tw_bind_node		__tw_common.skc_bind_node
116 #define tw_refcnt		__tw_common.skc_refcnt
117 #define tw_hash			__tw_common.skc_hash
118 #define tw_prot			__tw_common.skc_prot
119 #define tw_net			__tw_common.skc_net
120 	int			tw_timeout;
121 	volatile unsigned char	tw_substate;
122 	/* 3 bits hole, try to pack */
123 	unsigned char		tw_rcv_wscale;
124 	/* Socket demultiplex comparisons on incoming packets. */
125 	/* these five are in inet_sock */
126 	__be16			tw_sport;
127 	__be32			tw_daddr __attribute__((aligned(INET_TIMEWAIT_ADDRCMP_ALIGN_BYTES)));
128 	__be32			tw_rcv_saddr;
129 	__be16			tw_dport;
130 	__u16			tw_num;
131 	kmemcheck_bitfield_begin(flags);
132 	/* And these are ours. */
133 	unsigned int		tw_ipv6only     : 1,
134 				tw_transparent  : 1,
135 				tw_pad		: 14,	/* 14 bits hole */
136 				tw_ipv6_offset  : 16;
137 	kmemcheck_bitfield_end(flags);
138 	unsigned long		tw_ttd;
139 	struct inet_bind_bucket	*tw_tb;
140 	struct hlist_node	tw_death_node;
141 };
142 
143 static inline void inet_twsk_add_node_rcu(struct inet_timewait_sock *tw,
144 				      struct hlist_nulls_head *list)
145 {
146 	hlist_nulls_add_head_rcu(&tw->tw_node, list);
147 }
148 
149 static inline void inet_twsk_add_bind_node(struct inet_timewait_sock *tw,
150 					   struct hlist_head *list)
151 {
152 	hlist_add_head(&tw->tw_bind_node, list);
153 }
154 
155 static inline int inet_twsk_dead_hashed(const struct inet_timewait_sock *tw)
156 {
157 	return !hlist_unhashed(&tw->tw_death_node);
158 }
159 
160 static inline void inet_twsk_dead_node_init(struct inet_timewait_sock *tw)
161 {
162 	tw->tw_death_node.pprev = NULL;
163 }
164 
165 static inline void __inet_twsk_del_dead_node(struct inet_timewait_sock *tw)
166 {
167 	__hlist_del(&tw->tw_death_node);
168 	inet_twsk_dead_node_init(tw);
169 }
170 
171 static inline int inet_twsk_del_dead_node(struct inet_timewait_sock *tw)
172 {
173 	if (inet_twsk_dead_hashed(tw)) {
174 		__inet_twsk_del_dead_node(tw);
175 		return 1;
176 	}
177 	return 0;
178 }
179 
180 #define inet_twsk_for_each(tw, node, head) \
181 	hlist_nulls_for_each_entry(tw, node, head, tw_node)
182 
183 #define inet_twsk_for_each_inmate(tw, node, jail) \
184 	hlist_for_each_entry(tw, node, jail, tw_death_node)
185 
186 #define inet_twsk_for_each_inmate_safe(tw, node, safe, jail) \
187 	hlist_for_each_entry_safe(tw, node, safe, jail, tw_death_node)
188 
189 static inline struct inet_timewait_sock *inet_twsk(const struct sock *sk)
190 {
191 	return (struct inet_timewait_sock *)sk;
192 }
193 
194 static inline __be32 inet_rcv_saddr(const struct sock *sk)
195 {
196 	return likely(sk->sk_state != TCP_TIME_WAIT) ?
197 		inet_sk(sk)->inet_rcv_saddr : inet_twsk(sk)->tw_rcv_saddr;
198 }
199 
200 extern void inet_twsk_put(struct inet_timewait_sock *tw);
201 
202 extern int inet_twsk_unhash(struct inet_timewait_sock *tw);
203 
204 extern int inet_twsk_bind_unhash(struct inet_timewait_sock *tw,
205 				 struct inet_hashinfo *hashinfo);
206 
207 extern struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk,
208 						  const int state);
209 
210 extern void __inet_twsk_hashdance(struct inet_timewait_sock *tw,
211 				  struct sock *sk,
212 				  struct inet_hashinfo *hashinfo);
213 
214 extern void inet_twsk_schedule(struct inet_timewait_sock *tw,
215 			       struct inet_timewait_death_row *twdr,
216 			       const int timeo, const int timewait_len);
217 extern void inet_twsk_deschedule(struct inet_timewait_sock *tw,
218 				 struct inet_timewait_death_row *twdr);
219 
220 extern void inet_twsk_purge(struct inet_hashinfo *hashinfo,
221 			    struct inet_timewait_death_row *twdr, int family);
222 
223 static inline
224 struct net *twsk_net(const struct inet_timewait_sock *twsk)
225 {
226 #ifdef CONFIG_NET_NS
227 	return rcu_dereference(twsk->tw_net);
228 #else
229 	return &init_net;
230 #endif
231 }
232 
233 static inline
234 void twsk_net_set(struct inet_timewait_sock *twsk, struct net *net)
235 {
236 #ifdef CONFIG_NET_NS
237 	rcu_assign_pointer(twsk->tw_net, net);
238 #endif
239 }
240 #endif	/* _INET_TIMEWAIT_SOCK_ */
241