Loading...
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
25struct request_sock;
26struct sk_buff;
27struct dst_entry;
28struct proto;
29
30/* empty to "strongly type" an otherwise void parameter.
31 */
32struct request_values {
33};
34
35struct 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 */
54struct 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
70static 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
80static inline void __reqsk_free(struct request_sock *req)
81{
82 kmem_cache_free(req->rsk_ops->slab, req);
83}
84
85static inline void reqsk_free(struct request_sock *req)
86{
87 req->rsk_ops->destructor(req);
88 __reqsk_free(req);
89}
90
91extern 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 */
97struct 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 */
125struct 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
134extern int reqsk_queue_alloc(struct request_sock_queue *queue,
135 unsigned int nr_table_entries);
136
137extern void __reqsk_queue_destroy(struct request_sock_queue *queue);
138extern void reqsk_queue_destroy(struct request_sock_queue *queue);
139
140static 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
149static inline int reqsk_queue_empty(struct request_sock_queue *queue)
150{
151 return queue->rskq_accept_head == NULL;
152}
153
154static 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
163static 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
180static 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
193static 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
206static 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
217static 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
227static 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
232static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
233{
234 return queue->listen_opt->qlen_young;
235}
236
237static 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
242static 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 */
1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * NET Generic infrastructure for Network protocols.
4 *
5 * Definitions for request_sock
6 *
7 * Authors: Arnaldo Carvalho de Melo <acme@conectiva.com.br>
8 *
9 * From code originally in include/net/tcp.h
10 */
11#ifndef _REQUEST_SOCK_H
12#define _REQUEST_SOCK_H
13
14#include <linux/slab.h>
15#include <linux/spinlock.h>
16#include <linux/types.h>
17#include <linux/bug.h>
18#include <linux/refcount.h>
19
20#include <net/sock.h>
21
22struct request_sock;
23struct sk_buff;
24struct dst_entry;
25struct proto;
26
27struct request_sock_ops {
28 int family;
29 unsigned int obj_size;
30 struct kmem_cache *slab;
31 char *slab_name;
32 int (*rtx_syn_ack)(const struct sock *sk,
33 struct request_sock *req);
34 void (*send_ack)(const struct sock *sk, struct sk_buff *skb,
35 struct request_sock *req);
36 void (*send_reset)(const struct sock *sk,
37 struct sk_buff *skb);
38 void (*destructor)(struct request_sock *req);
39 void (*syn_ack_timeout)(const struct request_sock *req);
40};
41
42int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req);
43
44struct saved_syn {
45 u32 mac_hdrlen;
46 u32 network_hdrlen;
47 u32 tcp_hdrlen;
48 u8 data[];
49};
50
51/* struct request_sock - mini sock to represent a connection request
52 */
53struct request_sock {
54 struct sock_common __req_common;
55#define rsk_refcnt __req_common.skc_refcnt
56#define rsk_hash __req_common.skc_hash
57#define rsk_listener __req_common.skc_listener
58#define rsk_window_clamp __req_common.skc_window_clamp
59#define rsk_rcv_wnd __req_common.skc_rcv_wnd
60
61 struct request_sock *dl_next;
62 u16 mss;
63 u8 num_retrans; /* number of retransmits */
64 u8 syncookie:1; /* syncookie: encode tcpopts in timestamp */
65 u8 num_timeout:7; /* number of timeouts */
66 u32 ts_recent;
67 struct timer_list rsk_timer;
68 const struct request_sock_ops *rsk_ops;
69 struct sock *sk;
70 struct saved_syn *saved_syn;
71 u32 secid;
72 u32 peer_secid;
73};
74
75static inline struct request_sock *inet_reqsk(const struct sock *sk)
76{
77 return (struct request_sock *)sk;
78}
79
80static inline struct sock *req_to_sk(struct request_sock *req)
81{
82 return (struct sock *)req;
83}
84
85static inline struct request_sock *
86reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener,
87 bool attach_listener)
88{
89 struct request_sock *req;
90
91 req = kmem_cache_alloc(ops->slab, GFP_ATOMIC | __GFP_NOWARN);
92 if (!req)
93 return NULL;
94 req->rsk_listener = NULL;
95 if (attach_listener) {
96 if (unlikely(!refcount_inc_not_zero(&sk_listener->sk_refcnt))) {
97 kmem_cache_free(ops->slab, req);
98 return NULL;
99 }
100 req->rsk_listener = sk_listener;
101 }
102 req->rsk_ops = ops;
103 req_to_sk(req)->sk_prot = sk_listener->sk_prot;
104 sk_node_init(&req_to_sk(req)->sk_node);
105 sk_tx_queue_clear(req_to_sk(req));
106 req->saved_syn = NULL;
107 req->num_timeout = 0;
108 req->num_retrans = 0;
109 req->sk = NULL;
110 refcount_set(&req->rsk_refcnt, 0);
111
112 return req;
113}
114
115static inline void __reqsk_free(struct request_sock *req)
116{
117 req->rsk_ops->destructor(req);
118 if (req->rsk_listener)
119 sock_put(req->rsk_listener);
120 kfree(req->saved_syn);
121 kmem_cache_free(req->rsk_ops->slab, req);
122}
123
124static inline void reqsk_free(struct request_sock *req)
125{
126 WARN_ON_ONCE(refcount_read(&req->rsk_refcnt) != 0);
127 __reqsk_free(req);
128}
129
130static inline void reqsk_put(struct request_sock *req)
131{
132 if (refcount_dec_and_test(&req->rsk_refcnt))
133 reqsk_free(req);
134}
135
136/*
137 * For a TCP Fast Open listener -
138 * lock - protects the access to all the reqsk, which is co-owned by
139 * the listener and the child socket.
140 * qlen - pending TFO requests (still in TCP_SYN_RECV).
141 * max_qlen - max TFO reqs allowed before TFO is disabled.
142 *
143 * XXX (TFO) - ideally these fields can be made as part of "listen_sock"
144 * structure above. But there is some implementation difficulty due to
145 * listen_sock being part of request_sock_queue hence will be freed when
146 * a listener is stopped. But TFO related fields may continue to be
147 * accessed even after a listener is closed, until its sk_refcnt drops
148 * to 0 implying no more outstanding TFO reqs. One solution is to keep
149 * listen_opt around until sk_refcnt drops to 0. But there is some other
150 * complexity that needs to be resolved. E.g., a listener can be disabled
151 * temporarily through shutdown()->tcp_disconnect(), and re-enabled later.
152 */
153struct fastopen_queue {
154 struct request_sock *rskq_rst_head; /* Keep track of past TFO */
155 struct request_sock *rskq_rst_tail; /* requests that caused RST.
156 * This is part of the defense
157 * against spoofing attack.
158 */
159 spinlock_t lock;
160 int qlen; /* # of pending (TCP_SYN_RECV) reqs */
161 int max_qlen; /* != 0 iff TFO is currently enabled */
162
163 struct tcp_fastopen_context __rcu *ctx; /* cipher context for cookie */
164};
165
166/** struct request_sock_queue - queue of request_socks
167 *
168 * @rskq_accept_head - FIFO head of established children
169 * @rskq_accept_tail - FIFO tail of established children
170 * @rskq_defer_accept - User waits for some data after accept()
171 *
172 */
173struct request_sock_queue {
174 spinlock_t rskq_lock;
175 u8 rskq_defer_accept;
176
177 u32 synflood_warned;
178 atomic_t qlen;
179 atomic_t young;
180
181 struct request_sock *rskq_accept_head;
182 struct request_sock *rskq_accept_tail;
183 struct fastopen_queue fastopenq; /* Check max_qlen != 0 to determine
184 * if TFO is enabled.
185 */
186};
187
188void reqsk_queue_alloc(struct request_sock_queue *queue);
189
190void reqsk_fastopen_remove(struct sock *sk, struct request_sock *req,
191 bool reset);
192
193static inline bool reqsk_queue_empty(const struct request_sock_queue *queue)
194{
195 return READ_ONCE(queue->rskq_accept_head) == NULL;
196}
197
198static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue,
199 struct sock *parent)
200{
201 struct request_sock *req;
202
203 spin_lock_bh(&queue->rskq_lock);
204 req = queue->rskq_accept_head;
205 if (req) {
206 sk_acceptq_removed(parent);
207 WRITE_ONCE(queue->rskq_accept_head, req->dl_next);
208 if (queue->rskq_accept_head == NULL)
209 queue->rskq_accept_tail = NULL;
210 }
211 spin_unlock_bh(&queue->rskq_lock);
212 return req;
213}
214
215static inline void reqsk_queue_removed(struct request_sock_queue *queue,
216 const struct request_sock *req)
217{
218 if (req->num_timeout == 0)
219 atomic_dec(&queue->young);
220 atomic_dec(&queue->qlen);
221}
222
223static inline void reqsk_queue_added(struct request_sock_queue *queue)
224{
225 atomic_inc(&queue->young);
226 atomic_inc(&queue->qlen);
227}
228
229static inline int reqsk_queue_len(const struct request_sock_queue *queue)
230{
231 return atomic_read(&queue->qlen);
232}
233
234static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
235{
236 return atomic_read(&queue->young);
237}
238
239#endif /* _REQUEST_SOCK_H */