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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; /* True if
65 * 1) tcpopts needs to be encoded in
66 * TS of SYN+ACK
67 * 2) ACK is validated by BPF kfunc.
68 */
69 u8 num_timeout:7; /* number of timeouts */
70 u32 ts_recent;
71 struct timer_list rsk_timer;
72 const struct request_sock_ops *rsk_ops;
73 struct sock *sk;
74 struct saved_syn *saved_syn;
75 u32 secid;
76 u32 peer_secid;
77 u32 timeout;
78};
79
80static inline struct request_sock *inet_reqsk(const struct sock *sk)
81{
82 return (struct request_sock *)sk;
83}
84
85static inline struct sock *req_to_sk(struct request_sock *req)
86{
87 return (struct sock *)req;
88}
89
90/**
91 * skb_steal_sock - steal a socket from an sk_buff
92 * @skb: sk_buff to steal the socket from
93 * @refcounted: is set to true if the socket is reference-counted
94 * @prefetched: is set to true if the socket was assigned from bpf
95 */
96static inline struct sock *skb_steal_sock(struct sk_buff *skb,
97 bool *refcounted, bool *prefetched)
98{
99 struct sock *sk = skb->sk;
100
101 if (!sk) {
102 *prefetched = false;
103 *refcounted = false;
104 return NULL;
105 }
106
107 *prefetched = skb_sk_is_prefetched(skb);
108 if (*prefetched) {
109#if IS_ENABLED(CONFIG_SYN_COOKIES)
110 if (sk->sk_state == TCP_NEW_SYN_RECV && inet_reqsk(sk)->syncookie) {
111 struct request_sock *req = inet_reqsk(sk);
112
113 *refcounted = false;
114 sk = req->rsk_listener;
115 req->rsk_listener = NULL;
116 return sk;
117 }
118#endif
119 *refcounted = sk_is_refcounted(sk);
120 } else {
121 *refcounted = true;
122 }
123
124 skb->destructor = NULL;
125 skb->sk = NULL;
126 return sk;
127}
128
129static inline struct request_sock *
130reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener,
131 bool attach_listener)
132{
133 struct request_sock *req;
134
135 req = kmem_cache_alloc(ops->slab, GFP_ATOMIC | __GFP_NOWARN);
136 if (!req)
137 return NULL;
138 req->rsk_listener = NULL;
139 if (attach_listener) {
140 if (unlikely(!refcount_inc_not_zero(&sk_listener->sk_refcnt))) {
141 kmem_cache_free(ops->slab, req);
142 return NULL;
143 }
144 req->rsk_listener = sk_listener;
145 }
146 req->rsk_ops = ops;
147 req_to_sk(req)->sk_prot = sk_listener->sk_prot;
148 sk_node_init(&req_to_sk(req)->sk_node);
149 sk_tx_queue_clear(req_to_sk(req));
150 req->saved_syn = NULL;
151 req->syncookie = 0;
152 req->timeout = 0;
153 req->num_timeout = 0;
154 req->num_retrans = 0;
155 req->sk = NULL;
156 refcount_set(&req->rsk_refcnt, 0);
157
158 return req;
159}
160
161static inline void __reqsk_free(struct request_sock *req)
162{
163 req->rsk_ops->destructor(req);
164 if (req->rsk_listener)
165 sock_put(req->rsk_listener);
166 kfree(req->saved_syn);
167 kmem_cache_free(req->rsk_ops->slab, req);
168}
169
170static inline void reqsk_free(struct request_sock *req)
171{
172 WARN_ON_ONCE(refcount_read(&req->rsk_refcnt) != 0);
173 __reqsk_free(req);
174}
175
176static inline void reqsk_put(struct request_sock *req)
177{
178 if (refcount_dec_and_test(&req->rsk_refcnt))
179 reqsk_free(req);
180}
181
182/*
183 * For a TCP Fast Open listener -
184 * lock - protects the access to all the reqsk, which is co-owned by
185 * the listener and the child socket.
186 * qlen - pending TFO requests (still in TCP_SYN_RECV).
187 * max_qlen - max TFO reqs allowed before TFO is disabled.
188 *
189 * XXX (TFO) - ideally these fields can be made as part of "listen_sock"
190 * structure above. But there is some implementation difficulty due to
191 * listen_sock being part of request_sock_queue hence will be freed when
192 * a listener is stopped. But TFO related fields may continue to be
193 * accessed even after a listener is closed, until its sk_refcnt drops
194 * to 0 implying no more outstanding TFO reqs. One solution is to keep
195 * listen_opt around until sk_refcnt drops to 0. But there is some other
196 * complexity that needs to be resolved. E.g., a listener can be disabled
197 * temporarily through shutdown()->tcp_disconnect(), and re-enabled later.
198 */
199struct fastopen_queue {
200 struct request_sock *rskq_rst_head; /* Keep track of past TFO */
201 struct request_sock *rskq_rst_tail; /* requests that caused RST.
202 * This is part of the defense
203 * against spoofing attack.
204 */
205 spinlock_t lock;
206 int qlen; /* # of pending (TCP_SYN_RECV) reqs */
207 int max_qlen; /* != 0 iff TFO is currently enabled */
208
209 struct tcp_fastopen_context __rcu *ctx; /* cipher context for cookie */
210};
211
212/** struct request_sock_queue - queue of request_socks
213 *
214 * @rskq_accept_head - FIFO head of established children
215 * @rskq_accept_tail - FIFO tail of established children
216 * @rskq_defer_accept - User waits for some data after accept()
217 *
218 */
219struct request_sock_queue {
220 spinlock_t rskq_lock;
221 u8 rskq_defer_accept;
222
223 u32 synflood_warned;
224 atomic_t qlen;
225 atomic_t young;
226
227 struct request_sock *rskq_accept_head;
228 struct request_sock *rskq_accept_tail;
229 struct fastopen_queue fastopenq; /* Check max_qlen != 0 to determine
230 * if TFO is enabled.
231 */
232};
233
234void reqsk_queue_alloc(struct request_sock_queue *queue);
235
236void reqsk_fastopen_remove(struct sock *sk, struct request_sock *req,
237 bool reset);
238
239static inline bool reqsk_queue_empty(const struct request_sock_queue *queue)
240{
241 return READ_ONCE(queue->rskq_accept_head) == NULL;
242}
243
244static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue,
245 struct sock *parent)
246{
247 struct request_sock *req;
248
249 spin_lock_bh(&queue->rskq_lock);
250 req = queue->rskq_accept_head;
251 if (req) {
252 sk_acceptq_removed(parent);
253 WRITE_ONCE(queue->rskq_accept_head, req->dl_next);
254 if (queue->rskq_accept_head == NULL)
255 queue->rskq_accept_tail = NULL;
256 }
257 spin_unlock_bh(&queue->rskq_lock);
258 return req;
259}
260
261static inline void reqsk_queue_removed(struct request_sock_queue *queue,
262 const struct request_sock *req)
263{
264 if (req->num_timeout == 0)
265 atomic_dec(&queue->young);
266 atomic_dec(&queue->qlen);
267}
268
269static inline void reqsk_queue_added(struct request_sock_queue *queue)
270{
271 atomic_inc(&queue->young);
272 atomic_inc(&queue->qlen);
273}
274
275static inline int reqsk_queue_len(const struct request_sock_queue *queue)
276{
277 return atomic_read(&queue->qlen);
278}
279
280static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
281{
282 return atomic_read(&queue->young);
283}
284
285#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 u32 timeout;
74};
75
76static inline struct request_sock *inet_reqsk(const struct sock *sk)
77{
78 return (struct request_sock *)sk;
79}
80
81static inline struct sock *req_to_sk(struct request_sock *req)
82{
83 return (struct sock *)req;
84}
85
86static inline struct request_sock *
87reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener,
88 bool attach_listener)
89{
90 struct request_sock *req;
91
92 req = kmem_cache_alloc(ops->slab, GFP_ATOMIC | __GFP_NOWARN);
93 if (!req)
94 return NULL;
95 req->rsk_listener = NULL;
96 if (attach_listener) {
97 if (unlikely(!refcount_inc_not_zero(&sk_listener->sk_refcnt))) {
98 kmem_cache_free(ops->slab, req);
99 return NULL;
100 }
101 req->rsk_listener = sk_listener;
102 }
103 req->rsk_ops = ops;
104 req_to_sk(req)->sk_prot = sk_listener->sk_prot;
105 sk_node_init(&req_to_sk(req)->sk_node);
106 sk_tx_queue_clear(req_to_sk(req));
107 req->saved_syn = NULL;
108 req->timeout = 0;
109 req->num_timeout = 0;
110 req->num_retrans = 0;
111 req->sk = NULL;
112 refcount_set(&req->rsk_refcnt, 0);
113
114 return req;
115}
116
117static inline void __reqsk_free(struct request_sock *req)
118{
119 req->rsk_ops->destructor(req);
120 if (req->rsk_listener)
121 sock_put(req->rsk_listener);
122 kfree(req->saved_syn);
123 kmem_cache_free(req->rsk_ops->slab, req);
124}
125
126static inline void reqsk_free(struct request_sock *req)
127{
128 WARN_ON_ONCE(refcount_read(&req->rsk_refcnt) != 0);
129 __reqsk_free(req);
130}
131
132static inline void reqsk_put(struct request_sock *req)
133{
134 if (refcount_dec_and_test(&req->rsk_refcnt))
135 reqsk_free(req);
136}
137
138/*
139 * For a TCP Fast Open listener -
140 * lock - protects the access to all the reqsk, which is co-owned by
141 * the listener and the child socket.
142 * qlen - pending TFO requests (still in TCP_SYN_RECV).
143 * max_qlen - max TFO reqs allowed before TFO is disabled.
144 *
145 * XXX (TFO) - ideally these fields can be made as part of "listen_sock"
146 * structure above. But there is some implementation difficulty due to
147 * listen_sock being part of request_sock_queue hence will be freed when
148 * a listener is stopped. But TFO related fields may continue to be
149 * accessed even after a listener is closed, until its sk_refcnt drops
150 * to 0 implying no more outstanding TFO reqs. One solution is to keep
151 * listen_opt around until sk_refcnt drops to 0. But there is some other
152 * complexity that needs to be resolved. E.g., a listener can be disabled
153 * temporarily through shutdown()->tcp_disconnect(), and re-enabled later.
154 */
155struct fastopen_queue {
156 struct request_sock *rskq_rst_head; /* Keep track of past TFO */
157 struct request_sock *rskq_rst_tail; /* requests that caused RST.
158 * This is part of the defense
159 * against spoofing attack.
160 */
161 spinlock_t lock;
162 int qlen; /* # of pending (TCP_SYN_RECV) reqs */
163 int max_qlen; /* != 0 iff TFO is currently enabled */
164
165 struct tcp_fastopen_context __rcu *ctx; /* cipher context for cookie */
166};
167
168/** struct request_sock_queue - queue of request_socks
169 *
170 * @rskq_accept_head - FIFO head of established children
171 * @rskq_accept_tail - FIFO tail of established children
172 * @rskq_defer_accept - User waits for some data after accept()
173 *
174 */
175struct request_sock_queue {
176 spinlock_t rskq_lock;
177 u8 rskq_defer_accept;
178
179 u32 synflood_warned;
180 atomic_t qlen;
181 atomic_t young;
182
183 struct request_sock *rskq_accept_head;
184 struct request_sock *rskq_accept_tail;
185 struct fastopen_queue fastopenq; /* Check max_qlen != 0 to determine
186 * if TFO is enabled.
187 */
188};
189
190void reqsk_queue_alloc(struct request_sock_queue *queue);
191
192void reqsk_fastopen_remove(struct sock *sk, struct request_sock *req,
193 bool reset);
194
195static inline bool reqsk_queue_empty(const struct request_sock_queue *queue)
196{
197 return READ_ONCE(queue->rskq_accept_head) == NULL;
198}
199
200static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue,
201 struct sock *parent)
202{
203 struct request_sock *req;
204
205 spin_lock_bh(&queue->rskq_lock);
206 req = queue->rskq_accept_head;
207 if (req) {
208 sk_acceptq_removed(parent);
209 WRITE_ONCE(queue->rskq_accept_head, req->dl_next);
210 if (queue->rskq_accept_head == NULL)
211 queue->rskq_accept_tail = NULL;
212 }
213 spin_unlock_bh(&queue->rskq_lock);
214 return req;
215}
216
217static inline void reqsk_queue_removed(struct request_sock_queue *queue,
218 const struct request_sock *req)
219{
220 if (req->num_timeout == 0)
221 atomic_dec(&queue->young);
222 atomic_dec(&queue->qlen);
223}
224
225static inline void reqsk_queue_added(struct request_sock_queue *queue)
226{
227 atomic_inc(&queue->young);
228 atomic_inc(&queue->qlen);
229}
230
231static inline int reqsk_queue_len(const struct request_sock_queue *queue)
232{
233 return atomic_read(&queue->qlen);
234}
235
236static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
237{
238 return atomic_read(&queue->young);
239}
240
241#endif /* _REQUEST_SOCK_H */