xref: /openbmc/linux/include/net/request_sock.h (revision 4800cd83)
1 /*
2  * NET		Generic infrastructure for Network protocols.
3  *
4  *		Definitions for request_sock
5  *
6  * Authors:	Arnaldo Carvalho de Melo <acme@conectiva.com.br>
7  *
8  * 		From code originally in include/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 _REQUEST_SOCK_H
16 #define _REQUEST_SOCK_H
17 
18 #include <linux/slab.h>
19 #include <linux/spinlock.h>
20 #include <linux/types.h>
21 #include <linux/bug.h>
22 
23 #include <net/sock.h>
24 
25 struct request_sock;
26 struct sk_buff;
27 struct dst_entry;
28 struct proto;
29 
30 /* empty to "strongly type" an otherwise void parameter.
31  */
32 struct request_values {
33 };
34 
35 struct request_sock_ops {
36 	int		family;
37 	int		obj_size;
38 	struct kmem_cache	*slab;
39 	char		*slab_name;
40 	int		(*rtx_syn_ack)(struct sock *sk,
41 				       struct request_sock *req,
42 				       struct request_values *rvp);
43 	void		(*send_ack)(struct sock *sk, struct sk_buff *skb,
44 				    struct request_sock *req);
45 	void		(*send_reset)(struct sock *sk,
46 				      struct sk_buff *skb);
47 	void		(*destructor)(struct request_sock *req);
48 	void		(*syn_ack_timeout)(struct sock *sk,
49 					   struct request_sock *req);
50 };
51 
52 /* struct request_sock - mini sock to represent a connection request
53  */
54 struct request_sock {
55 	struct request_sock		*dl_next; /* Must be first member! */
56 	u16				mss;
57 	u8				retrans;
58 	u8				cookie_ts; /* syncookie: encode tcpopts in timestamp */
59 	/* The following two fields can be easily recomputed I think -AK */
60 	u32				window_clamp; /* window clamp at creation time */
61 	u32				rcv_wnd;	  /* rcv_wnd offered first time */
62 	u32				ts_recent;
63 	unsigned long			expires;
64 	const struct request_sock_ops	*rsk_ops;
65 	struct sock			*sk;
66 	u32				secid;
67 	u32				peer_secid;
68 };
69 
70 static inline struct request_sock *reqsk_alloc(const struct request_sock_ops *ops)
71 {
72 	struct request_sock *req = kmem_cache_alloc(ops->slab, GFP_ATOMIC);
73 
74 	if (req != NULL)
75 		req->rsk_ops = ops;
76 
77 	return req;
78 }
79 
80 static inline void __reqsk_free(struct request_sock *req)
81 {
82 	kmem_cache_free(req->rsk_ops->slab, req);
83 }
84 
85 static inline void reqsk_free(struct request_sock *req)
86 {
87 	req->rsk_ops->destructor(req);
88 	__reqsk_free(req);
89 }
90 
91 extern int sysctl_max_syn_backlog;
92 
93 /** struct listen_sock - listen state
94  *
95  * @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs
96  */
97 struct listen_sock {
98 	u8			max_qlen_log;
99 	/* 3 bytes hole, try to use */
100 	int			qlen;
101 	int			qlen_young;
102 	int			clock_hand;
103 	u32			hash_rnd;
104 	u32			nr_table_entries;
105 	struct request_sock	*syn_table[0];
106 };
107 
108 /** struct request_sock_queue - queue of request_socks
109  *
110  * @rskq_accept_head - FIFO head of established children
111  * @rskq_accept_tail - FIFO tail of established children
112  * @rskq_defer_accept - User waits for some data after accept()
113  * @syn_wait_lock - serializer
114  *
115  * %syn_wait_lock is necessary only to avoid proc interface having to grab the main
116  * lock sock while browsing the listening hash (otherwise it's deadlock prone).
117  *
118  * This lock is acquired in read mode only from listening_get_next() seq_file
119  * op and it's acquired in write mode _only_ from code that is actively
120  * changing rskq_accept_head. All readers that are holding the master sock lock
121  * don't need to grab this lock in read mode too as rskq_accept_head. writes
122  * are always protected from the main sock lock.
123  */
124 struct request_sock_queue {
125 	struct request_sock	*rskq_accept_head;
126 	struct request_sock	*rskq_accept_tail;
127 	rwlock_t		syn_wait_lock;
128 	u8			rskq_defer_accept;
129 	/* 3 bytes hole, try to pack */
130 	struct listen_sock	*listen_opt;
131 };
132 
133 extern int reqsk_queue_alloc(struct request_sock_queue *queue,
134 			     unsigned int nr_table_entries);
135 
136 extern void __reqsk_queue_destroy(struct request_sock_queue *queue);
137 extern void reqsk_queue_destroy(struct request_sock_queue *queue);
138 
139 static inline struct request_sock *
140 	reqsk_queue_yank_acceptq(struct request_sock_queue *queue)
141 {
142 	struct request_sock *req = queue->rskq_accept_head;
143 
144 	queue->rskq_accept_head = NULL;
145 	return req;
146 }
147 
148 static inline int reqsk_queue_empty(struct request_sock_queue *queue)
149 {
150 	return queue->rskq_accept_head == NULL;
151 }
152 
153 static inline void reqsk_queue_unlink(struct request_sock_queue *queue,
154 				      struct request_sock *req,
155 				      struct request_sock **prev_req)
156 {
157 	write_lock(&queue->syn_wait_lock);
158 	*prev_req = req->dl_next;
159 	write_unlock(&queue->syn_wait_lock);
160 }
161 
162 static inline void reqsk_queue_add(struct request_sock_queue *queue,
163 				   struct request_sock *req,
164 				   struct sock *parent,
165 				   struct sock *child)
166 {
167 	req->sk = child;
168 	sk_acceptq_added(parent);
169 
170 	if (queue->rskq_accept_head == NULL)
171 		queue->rskq_accept_head = req;
172 	else
173 		queue->rskq_accept_tail->dl_next = req;
174 
175 	queue->rskq_accept_tail = req;
176 	req->dl_next = NULL;
177 }
178 
179 static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue)
180 {
181 	struct request_sock *req = queue->rskq_accept_head;
182 
183 	WARN_ON(req == NULL);
184 
185 	queue->rskq_accept_head = req->dl_next;
186 	if (queue->rskq_accept_head == NULL)
187 		queue->rskq_accept_tail = NULL;
188 
189 	return req;
190 }
191 
192 static inline struct sock *reqsk_queue_get_child(struct request_sock_queue *queue,
193 						 struct sock *parent)
194 {
195 	struct request_sock *req = reqsk_queue_remove(queue);
196 	struct sock *child = req->sk;
197 
198 	WARN_ON(child == NULL);
199 
200 	sk_acceptq_removed(parent);
201 	__reqsk_free(req);
202 	return child;
203 }
204 
205 static inline int reqsk_queue_removed(struct request_sock_queue *queue,
206 				      struct request_sock *req)
207 {
208 	struct listen_sock *lopt = queue->listen_opt;
209 
210 	if (req->retrans == 0)
211 		--lopt->qlen_young;
212 
213 	return --lopt->qlen;
214 }
215 
216 static inline int reqsk_queue_added(struct request_sock_queue *queue)
217 {
218 	struct listen_sock *lopt = queue->listen_opt;
219 	const int prev_qlen = lopt->qlen;
220 
221 	lopt->qlen_young++;
222 	lopt->qlen++;
223 	return prev_qlen;
224 }
225 
226 static inline int reqsk_queue_len(const struct request_sock_queue *queue)
227 {
228 	return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0;
229 }
230 
231 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
232 {
233 	return queue->listen_opt->qlen_young;
234 }
235 
236 static inline int reqsk_queue_is_full(const struct request_sock_queue *queue)
237 {
238 	return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log;
239 }
240 
241 static inline void reqsk_queue_hash_req(struct request_sock_queue *queue,
242 					u32 hash, struct request_sock *req,
243 					unsigned long timeout)
244 {
245 	struct listen_sock *lopt = queue->listen_opt;
246 
247 	req->expires = jiffies + timeout;
248 	req->retrans = 0;
249 	req->sk = NULL;
250 	req->dl_next = lopt->syn_table[hash];
251 
252 	write_lock(&queue->syn_wait_lock);
253 	lopt->syn_table[hash] = req;
254 	write_unlock(&queue->syn_wait_lock);
255 }
256 
257 #endif /* _REQUEST_SOCK_H */
258