2 * NET Generic infrastructure for Network protocols.
4 * Definitions for request_sock
6 * Authors: Arnaldo Carvalho de Melo <acme@conectiva.com.br>
8 * From code originally in include/net/tcp.h
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.
15 #ifndef _REQUEST_SOCK_H
16 #define _REQUEST_SOCK_H
18 #include <linux/slab.h>
19 #include <linux/spinlock.h>
20 #include <linux/types.h>
21 #include <linux/bug.h>
30 struct request_sock_ops
{
33 struct kmem_cache
*slab
;
35 int (*rtx_syn_ack
)(const struct sock
*sk
,
36 struct request_sock
*req
);
37 void (*send_ack
)(const struct sock
*sk
, struct sk_buff
*skb
,
38 struct request_sock
*req
);
39 void (*send_reset
)(const struct sock
*sk
,
41 void (*destructor
)(struct request_sock
*req
);
42 void (*syn_ack_timeout
)(const struct request_sock
*req
);
45 int inet_rtx_syn_ack(const struct sock
*parent
, struct request_sock
*req
);
47 /* struct request_sock - mini sock to represent a connection request
50 struct sock_common __req_common
;
51 #define rsk_refcnt __req_common.skc_refcnt
52 #define rsk_hash __req_common.skc_hash
53 #define rsk_listener __req_common.skc_listener
54 #define rsk_window_clamp __req_common.skc_window_clamp
55 #define rsk_rcv_wnd __req_common.skc_rcv_wnd
57 struct request_sock
*dl_next
;
59 u8 num_retrans
; /* number of retransmits */
60 u8 cookie_ts
:1; /* syncookie: encode tcpopts in timestamp */
61 u8 num_timeout
:7; /* number of timeouts */
63 struct timer_list rsk_timer
;
64 const struct request_sock_ops
*rsk_ops
;
71 static inline struct request_sock
*inet_reqsk(struct sock
*sk
)
73 return (struct request_sock
*)sk
;
76 static inline struct sock
*req_to_sk(struct request_sock
*req
)
78 return (struct sock
*)req
;
81 static inline struct request_sock
*
82 reqsk_alloc(const struct request_sock_ops
*ops
, struct sock
*sk_listener
,
85 struct request_sock
*req
;
87 req
= kmem_cache_alloc(ops
->slab
, GFP_ATOMIC
| __GFP_NOWARN
);
91 if (attach_listener
) {
92 sock_hold(sk_listener
);
93 req
->rsk_listener
= sk_listener
;
95 req
->rsk_listener
= NULL
;
97 req_to_sk(req
)->sk_prot
= sk_listener
->sk_prot
;
98 sk_node_init(&req_to_sk(req
)->sk_node
);
99 sk_tx_queue_clear(req_to_sk(req
));
100 req
->saved_syn
= NULL
;
101 /* Following is temporary. It is coupled with debugging
102 * helpers in reqsk_put() & reqsk_free()
104 atomic_set(&req
->rsk_refcnt
, 0);
109 static inline void reqsk_free(struct request_sock
*req
)
111 /* temporary debugging */
112 WARN_ON_ONCE(atomic_read(&req
->rsk_refcnt
) != 0);
114 req
->rsk_ops
->destructor(req
);
115 if (req
->rsk_listener
)
116 sock_put(req
->rsk_listener
);
117 kfree(req
->saved_syn
);
118 kmem_cache_free(req
->rsk_ops
->slab
, req
);
121 static inline void reqsk_put(struct request_sock
*req
)
123 if (atomic_dec_and_test(&req
->rsk_refcnt
))
127 extern int sysctl_max_syn_backlog
;
130 * For a TCP Fast Open listener -
131 * lock - protects the access to all the reqsk, which is co-owned by
132 * the listener and the child socket.
133 * qlen - pending TFO requests (still in TCP_SYN_RECV).
134 * max_qlen - max TFO reqs allowed before TFO is disabled.
136 * XXX (TFO) - ideally these fields can be made as part of "listen_sock"
137 * structure above. But there is some implementation difficulty due to
138 * listen_sock being part of request_sock_queue hence will be freed when
139 * a listener is stopped. But TFO related fields may continue to be
140 * accessed even after a listener is closed, until its sk_refcnt drops
141 * to 0 implying no more outstanding TFO reqs. One solution is to keep
142 * listen_opt around until sk_refcnt drops to 0. But there is some other
143 * complexity that needs to be resolved. E.g., a listener can be disabled
144 * temporarily through shutdown()->tcp_disconnect(), and re-enabled later.
146 struct fastopen_queue
{
147 struct request_sock
*rskq_rst_head
; /* Keep track of past TFO */
148 struct request_sock
*rskq_rst_tail
; /* requests that caused RST.
149 * This is part of the defense
150 * against spoofing attack.
153 int qlen
; /* # of pending (TCP_SYN_RECV) reqs */
154 int max_qlen
; /* != 0 iff TFO is currently enabled */
157 /** struct request_sock_queue - queue of request_socks
159 * @rskq_accept_head - FIFO head of established children
160 * @rskq_accept_tail - FIFO tail of established children
161 * @rskq_defer_accept - User waits for some data after accept()
164 struct request_sock_queue
{
165 spinlock_t rskq_lock
;
166 u8 rskq_defer_accept
;
172 struct request_sock
*rskq_accept_head
;
173 struct request_sock
*rskq_accept_tail
;
174 struct fastopen_queue fastopenq
; /* Check max_qlen != 0 to determine
179 void reqsk_queue_alloc(struct request_sock_queue
*queue
);
181 void reqsk_fastopen_remove(struct sock
*sk
, struct request_sock
*req
,
184 static inline bool reqsk_queue_empty(const struct request_sock_queue
*queue
)
186 return queue
->rskq_accept_head
== NULL
;
189 static inline struct request_sock
*reqsk_queue_remove(struct request_sock_queue
*queue
,
192 struct request_sock
*req
;
194 spin_lock_bh(&queue
->rskq_lock
);
195 req
= queue
->rskq_accept_head
;
197 sk_acceptq_removed(parent
);
198 queue
->rskq_accept_head
= req
->dl_next
;
199 if (queue
->rskq_accept_head
== NULL
)
200 queue
->rskq_accept_tail
= NULL
;
202 spin_unlock_bh(&queue
->rskq_lock
);
206 static inline void reqsk_queue_removed(struct request_sock_queue
*queue
,
207 const struct request_sock
*req
)
209 if (req
->num_timeout
== 0)
210 atomic_dec(&queue
->young
);
211 atomic_dec(&queue
->qlen
);
214 static inline void reqsk_queue_added(struct request_sock_queue
*queue
)
216 atomic_inc(&queue
->young
);
217 atomic_inc(&queue
->qlen
);
220 static inline int reqsk_queue_len(const struct request_sock_queue
*queue
)
222 return atomic_read(&queue
->qlen
);
225 static inline int reqsk_queue_len_young(const struct request_sock_queue
*queue
)
227 return atomic_read(&queue
->young
);
230 #endif /* _REQUEST_SOCK_H */