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
reqsk_alloc(const struct request_sock_ops * ops)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
__reqsk_free(struct request_sock * req)80 static inline void __reqsk_free(struct request_sock *req)
81 {
82 kmem_cache_free(req->rsk_ops->slab, req);
83 }
84
reqsk_free(struct request_sock * req)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 u8 synflood_warned;
100 /* 2 bytes hole, try to use */
101 int qlen;
102 int qlen_young;
103 int clock_hand;
104 u32 hash_rnd;
105 u32 nr_table_entries;
106 struct request_sock *syn_table[0];
107 };
108
109 /** struct request_sock_queue - queue of request_socks
110 *
111 * @rskq_accept_head - FIFO head of established children
112 * @rskq_accept_tail - FIFO tail of established children
113 * @rskq_defer_accept - User waits for some data after accept()
114 * @syn_wait_lock - serializer
115 *
116 * %syn_wait_lock is necessary only to avoid proc interface having to grab the main
117 * lock sock while browsing the listening hash (otherwise it's deadlock prone).
118 *
119 * This lock is acquired in read mode only from listening_get_next() seq_file
120 * op and it's acquired in write mode _only_ from code that is actively
121 * changing rskq_accept_head. All readers that are holding the master sock lock
122 * don't need to grab this lock in read mode too as rskq_accept_head. writes
123 * are always protected from the main sock lock.
124 */
125 struct request_sock_queue {
126 struct request_sock *rskq_accept_head;
127 struct request_sock *rskq_accept_tail;
128 rwlock_t syn_wait_lock;
129 u8 rskq_defer_accept;
130 /* 3 bytes hole, try to pack */
131 struct listen_sock *listen_opt;
132 };
133
134 extern int reqsk_queue_alloc(struct request_sock_queue *queue,
135 unsigned int nr_table_entries);
136
137 extern void __reqsk_queue_destroy(struct request_sock_queue *queue);
138 extern void reqsk_queue_destroy(struct request_sock_queue *queue);
139
140 static inline struct request_sock *
reqsk_queue_yank_acceptq(struct request_sock_queue * queue)141 reqsk_queue_yank_acceptq(struct request_sock_queue *queue)
142 {
143 struct request_sock *req = queue->rskq_accept_head;
144
145 queue->rskq_accept_head = NULL;
146 return req;
147 }
148
reqsk_queue_empty(struct request_sock_queue * queue)149 static inline int reqsk_queue_empty(struct request_sock_queue *queue)
150 {
151 return queue->rskq_accept_head == NULL;
152 }
153
reqsk_queue_unlink(struct request_sock_queue * queue,struct request_sock * req,struct request_sock ** prev_req)154 static inline void reqsk_queue_unlink(struct request_sock_queue *queue,
155 struct request_sock *req,
156 struct request_sock **prev_req)
157 {
158 write_lock(&queue->syn_wait_lock);
159 *prev_req = req->dl_next;
160 write_unlock(&queue->syn_wait_lock);
161 }
162
reqsk_queue_add(struct request_sock_queue * queue,struct request_sock * req,struct sock * parent,struct sock * child)163 static inline void reqsk_queue_add(struct request_sock_queue *queue,
164 struct request_sock *req,
165 struct sock *parent,
166 struct sock *child)
167 {
168 req->sk = child;
169 sk_acceptq_added(parent);
170
171 if (queue->rskq_accept_head == NULL)
172 queue->rskq_accept_head = req;
173 else
174 queue->rskq_accept_tail->dl_next = req;
175
176 queue->rskq_accept_tail = req;
177 req->dl_next = NULL;
178 }
179
reqsk_queue_remove(struct request_sock_queue * queue)180 static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue)
181 {
182 struct request_sock *req = queue->rskq_accept_head;
183
184 WARN_ON(req == NULL);
185
186 queue->rskq_accept_head = req->dl_next;
187 if (queue->rskq_accept_head == NULL)
188 queue->rskq_accept_tail = NULL;
189
190 return req;
191 }
192
reqsk_queue_get_child(struct request_sock_queue * queue,struct sock * parent)193 static inline struct sock *reqsk_queue_get_child(struct request_sock_queue *queue,
194 struct sock *parent)
195 {
196 struct request_sock *req = reqsk_queue_remove(queue);
197 struct sock *child = req->sk;
198
199 WARN_ON(child == NULL);
200
201 sk_acceptq_removed(parent);
202 __reqsk_free(req);
203 return child;
204 }
205
reqsk_queue_removed(struct request_sock_queue * queue,struct request_sock * req)206 static inline int reqsk_queue_removed(struct request_sock_queue *queue,
207 struct request_sock *req)
208 {
209 struct listen_sock *lopt = queue->listen_opt;
210
211 if (req->retrans == 0)
212 --lopt->qlen_young;
213
214 return --lopt->qlen;
215 }
216
reqsk_queue_added(struct request_sock_queue * queue)217 static inline int reqsk_queue_added(struct request_sock_queue *queue)
218 {
219 struct listen_sock *lopt = queue->listen_opt;
220 const int prev_qlen = lopt->qlen;
221
222 lopt->qlen_young++;
223 lopt->qlen++;
224 return prev_qlen;
225 }
226
reqsk_queue_len(const struct request_sock_queue * queue)227 static inline int reqsk_queue_len(const struct request_sock_queue *queue)
228 {
229 return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0;
230 }
231
reqsk_queue_len_young(const struct request_sock_queue * queue)232 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
233 {
234 return queue->listen_opt->qlen_young;
235 }
236
reqsk_queue_is_full(const struct request_sock_queue * queue)237 static inline int reqsk_queue_is_full(const struct request_sock_queue *queue)
238 {
239 return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log;
240 }
241
reqsk_queue_hash_req(struct request_sock_queue * queue,u32 hash,struct request_sock * req,unsigned long timeout)242 static inline void reqsk_queue_hash_req(struct request_sock_queue *queue,
243 u32 hash, struct request_sock *req,
244 unsigned long timeout)
245 {
246 struct listen_sock *lopt = queue->listen_opt;
247
248 req->expires = jiffies + timeout;
249 req->retrans = 0;
250 req->sk = NULL;
251 req->dl_next = lopt->syn_table[hash];
252
253 write_lock(&queue->syn_wait_lock);
254 lopt->syn_table[hash] = req;
255 write_unlock(&queue->syn_wait_lock);
256 }
257
258 #endif /* _REQUEST_SOCK_H */
259