tcp: Change possible SYN flooding messages
[linux-3.10.git] / include / net / request_sock.h
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         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 *
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
149 static inline int reqsk_queue_empty(struct request_sock_queue *queue)
150 {
151         return queue->rskq_accept_head == NULL;
152 }
153
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
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
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
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
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
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
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
232 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
233 {
234         return queue->listen_opt->qlen_young;
235 }
236
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
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 */