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>
22 #include <linux/refcount.h>
31 struct request_sock_ops {
33 unsigned int obj_size;
34 struct kmem_cache *slab;
36 int (*rtx_syn_ack)(const struct sock *sk,
37 struct request_sock *req);
38 void (*send_ack)(const struct sock *sk, struct sk_buff *skb,
39 struct request_sock *req);
40 void (*send_reset)(const struct sock *sk,
42 void (*destructor)(struct request_sock *req);
43 void (*syn_ack_timeout)(const struct request_sock *req);
46 int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req);
48 /* struct request_sock - mini sock to represent a connection request
51 struct sock_common __req_common;
52 #define rsk_refcnt __req_common.skc_refcnt
53 #define rsk_hash __req_common.skc_hash
54 #define rsk_listener __req_common.skc_listener
55 #define rsk_window_clamp __req_common.skc_window_clamp
56 #define rsk_rcv_wnd __req_common.skc_rcv_wnd
58 struct request_sock *dl_next;
60 u8 num_retrans; /* number of retransmits */
61 u8 cookie_ts:1; /* syncookie: encode tcpopts in timestamp */
62 u8 num_timeout:7; /* number of timeouts */
64 struct timer_list rsk_timer;
65 const struct request_sock_ops *rsk_ops;
72 static inline struct request_sock *inet_reqsk(const struct sock *sk)
74 return (struct request_sock *)sk;
77 static inline struct sock *req_to_sk(struct request_sock *req)
79 return (struct sock *)req;
82 static inline struct request_sock *
83 reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener,
86 struct request_sock *req;
88 req = kmem_cache_alloc(ops->slab, GFP_ATOMIC | __GFP_NOWARN);
91 req->rsk_listener = NULL;
92 if (attach_listener) {
93 if (unlikely(!refcount_inc_not_zero(&sk_listener->sk_refcnt))) {
94 kmem_cache_free(ops->slab, req);
97 req->rsk_listener = sk_listener;
100 req_to_sk(req)->sk_prot = sk_listener->sk_prot;
101 sk_node_init(&req_to_sk(req)->sk_node);
102 sk_tx_queue_clear(req_to_sk(req));
103 req->saved_syn = NULL;
104 refcount_set(&req->rsk_refcnt, 0);
109 static inline void __reqsk_free(struct request_sock *req)
111 req->rsk_ops->destructor(req);
112 if (req->rsk_listener)
113 sock_put(req->rsk_listener);
114 kfree(req->saved_syn);
115 kmem_cache_free(req->rsk_ops->slab, req);
118 static inline void reqsk_free(struct request_sock *req)
120 WARN_ON_ONCE(refcount_read(&req->rsk_refcnt) != 0);
124 static inline void reqsk_put(struct request_sock *req)
126 if (refcount_dec_and_test(&req->rsk_refcnt))
131 * For a TCP Fast Open listener -
132 * lock - protects the access to all the reqsk, which is co-owned by
133 * the listener and the child socket.
134 * qlen - pending TFO requests (still in TCP_SYN_RECV).
135 * max_qlen - max TFO reqs allowed before TFO is disabled.
137 * XXX (TFO) - ideally these fields can be made as part of "listen_sock"
138 * structure above. But there is some implementation difficulty due to
139 * listen_sock being part of request_sock_queue hence will be freed when
140 * a listener is stopped. But TFO related fields may continue to be
141 * accessed even after a listener is closed, until its sk_refcnt drops
142 * to 0 implying no more outstanding TFO reqs. One solution is to keep
143 * listen_opt around until sk_refcnt drops to 0. But there is some other
144 * complexity that needs to be resolved. E.g., a listener can be disabled
145 * temporarily through shutdown()->tcp_disconnect(), and re-enabled later.
147 struct fastopen_queue {
148 struct request_sock *rskq_rst_head; /* Keep track of past TFO */
149 struct request_sock *rskq_rst_tail; /* requests that caused RST.
150 * This is part of the defense
151 * against spoofing attack.
154 int qlen; /* # of pending (TCP_SYN_RECV) reqs */
155 int max_qlen; /* != 0 iff TFO is currently enabled */
157 struct tcp_fastopen_context __rcu *ctx; /* cipher context for cookie */
160 /** struct request_sock_queue - queue of request_socks
162 * @rskq_accept_head - FIFO head of established children
163 * @rskq_accept_tail - FIFO tail of established children
164 * @rskq_defer_accept - User waits for some data after accept()
167 struct request_sock_queue {
168 spinlock_t rskq_lock;
169 u8 rskq_defer_accept;
175 struct request_sock *rskq_accept_head;
176 struct request_sock *rskq_accept_tail;
177 struct fastopen_queue fastopenq; /* Check max_qlen != 0 to determine
182 void reqsk_queue_alloc(struct request_sock_queue *queue);
184 void reqsk_fastopen_remove(struct sock *sk, struct request_sock *req,
187 static inline bool reqsk_queue_empty(const struct request_sock_queue *queue)
189 return queue->rskq_accept_head == NULL;
192 static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue,
195 struct request_sock *req;
197 spin_lock_bh(&queue->rskq_lock);
198 req = queue->rskq_accept_head;
200 sk_acceptq_removed(parent);
201 queue->rskq_accept_head = req->dl_next;
202 if (queue->rskq_accept_head == NULL)
203 queue->rskq_accept_tail = NULL;
205 spin_unlock_bh(&queue->rskq_lock);
209 static inline void reqsk_queue_removed(struct request_sock_queue *queue,
210 const struct request_sock *req)
212 if (req->num_timeout == 0)
213 atomic_dec(&queue->young);
214 atomic_dec(&queue->qlen);
217 static inline void reqsk_queue_added(struct request_sock_queue *queue)
219 atomic_inc(&queue->young);
220 atomic_inc(&queue->qlen);
223 static inline int reqsk_queue_len(const struct request_sock_queue *queue)
225 return atomic_read(&queue->qlen);
228 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
230 return atomic_read(&queue->young);
233 #endif /* _REQUEST_SOCK_H */