1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3  * NET		Generic infrastructure for INET connection oriented protocols.
4  *
5  *		Definitions for inet_connection_sock
6  *
7  * Authors:	Many people, see the TCP sources
8  *
9  * 		From code originally in TCP
10  */
11 #ifndef _INET_CONNECTION_SOCK_H
12 #define _INET_CONNECTION_SOCK_H
13 
14 #include <linux/compiler.h>
15 #include <linux/string.h>
16 #include <linux/timer.h>
17 #include <linux/poll.h>
18 #include <linux/kernel.h>
19 #include <linux/sockptr.h>
20 
21 #include <net/inet_sock.h>
22 #include <net/request_sock.h>
23 
24 /* Cancel timers, when they are not required. */
25 #undef INET_CSK_CLEAR_TIMERS
26 
27 struct inet_bind_bucket;
28 struct inet_bind2_bucket;
29 struct tcp_congestion_ops;
30 
31 /*
32  * Pointers to address related TCP functions
33  * (i.e. things that depend on the address family)
34  */
35 struct inet_connection_sock_af_ops {
36 	int	    (*queue_xmit)(struct sock *sk, struct sk_buff *skb, struct flowi *fl);
37 	void	    (*send_check)(struct sock *sk, struct sk_buff *skb);
38 	int	    (*rebuild_header)(struct sock *sk);
39 	void	    (*sk_rx_dst_set)(struct sock *sk, const struct sk_buff *skb);
40 	int	    (*conn_request)(struct sock *sk, struct sk_buff *skb);
41 	struct sock *(*syn_recv_sock)(const struct sock *sk, struct sk_buff *skb,
42 				      struct request_sock *req,
43 				      struct dst_entry *dst,
44 				      struct request_sock *req_unhash,
45 				      bool *own_req);
46 	u16	    net_header_len;
47 	u16	    net_frag_header_len;
48 	u16	    sockaddr_len;
49 	int	    (*setsockopt)(struct sock *sk, int level, int optname,
50 				  sockptr_t optval, unsigned int optlen);
51 	int	    (*getsockopt)(struct sock *sk, int level, int optname,
52 				  char __user *optval, int __user *optlen);
53 	void	    (*addr2sockaddr)(struct sock *sk, struct sockaddr *);
54 	void	    (*mtu_reduced)(struct sock *sk);
55 };
56 
57 /** inet_connection_sock - INET connection oriented sock
58  *
59  * @icsk_accept_queue:	   FIFO of established children
60  * @icsk_bind_hash:	   Bind node
61  * @icsk_bind2_hash:	   Bind node in the bhash2 table
62  * @icsk_timeout:	   Timeout
63  * @icsk_retransmit_timer: Resend (no ack)
64  * @icsk_rto:		   Retransmit timeout
65  * @icsk_pmtu_cookie	   Last pmtu seen by socket
66  * @icsk_ca_ops		   Pluggable congestion control hook
67  * @icsk_af_ops		   Operations which are AF_INET{4,6} specific
68  * @icsk_ulp_ops	   Pluggable ULP control hook
69  * @icsk_ulp_data	   ULP private data
70  * @icsk_clean_acked	   Clean acked data hook
71  * @icsk_ca_state:	   Congestion control state
72  * @icsk_retransmits:	   Number of unrecovered [RTO] timeouts
73  * @icsk_pending:	   Scheduled timer event
74  * @icsk_backoff:	   Backoff
75  * @icsk_syn_retries:      Number of allowed SYN (or equivalent) retries
76  * @icsk_probes_out:	   unanswered 0 window probes
77  * @icsk_ext_hdr_len:	   Network protocol overhead (IP/IPv6 options)
78  * @icsk_ack:		   Delayed ACK control data
79  * @icsk_mtup;		   MTU probing control data
80  * @icsk_probes_tstamp:    Probe timestamp (cleared by non-zero window ack)
81  * @icsk_user_timeout:	   TCP_USER_TIMEOUT value
82  */
83 struct inet_connection_sock {
84 	/* inet_sock has to be the first member! */
85 	struct inet_sock	  icsk_inet;
86 	struct request_sock_queue icsk_accept_queue;
87 	struct inet_bind_bucket	  *icsk_bind_hash;
88 	struct inet_bind2_bucket  *icsk_bind2_hash;
89 	unsigned long		  icsk_timeout;
90  	struct timer_list	  icsk_retransmit_timer;
91  	struct timer_list	  icsk_delack_timer;
92 	__u32			  icsk_rto;
93 	__u32                     icsk_rto_min;
94 	__u32                     icsk_delack_max;
95 	__u32			  icsk_pmtu_cookie;
96 	const struct tcp_congestion_ops *icsk_ca_ops;
97 	const struct inet_connection_sock_af_ops *icsk_af_ops;
98 	const struct tcp_ulp_ops  *icsk_ulp_ops;
99 	void __rcu		  *icsk_ulp_data;
100 	void (*icsk_clean_acked)(struct sock *sk, u32 acked_seq);
101 	unsigned int		  (*icsk_sync_mss)(struct sock *sk, u32 pmtu);
102 	__u8			  icsk_ca_state:5,
103 				  icsk_ca_initialized:1,
104 				  icsk_ca_setsockopt:1,
105 				  icsk_ca_dst_locked:1;
106 	__u8			  icsk_retransmits;
107 	__u8			  icsk_pending;
108 	__u8			  icsk_backoff;
109 	__u8			  icsk_syn_retries;
110 	__u8			  icsk_probes_out;
111 	__u16			  icsk_ext_hdr_len;
112 	struct {
113 		__u8		  pending;	 /* ACK is pending			   */
114 		__u8		  quick;	 /* Scheduled number of quick acks	   */
115 		__u8		  pingpong;	 /* The session is interactive		   */
116 		__u8		  retry;	 /* Number of attempts			   */
117 		__u32		  ato;		 /* Predicted tick of soft clock	   */
118 		unsigned long	  timeout;	 /* Currently scheduled timeout		   */
119 		__u32		  lrcvtime;	 /* timestamp of last received data packet */
120 		__u16		  last_seg_size; /* Size of last incoming segment	   */
121 		__u16		  rcv_mss;	 /* MSS used for delayed ACK decisions	   */
122 	} icsk_ack;
123 	struct {
124 		/* Range of MTUs to search */
125 		int		  search_high;
126 		int		  search_low;
127 
128 		/* Information on the current probe. */
129 		u32		  probe_size:31,
130 		/* Is the MTUP feature enabled for this connection? */
131 				  enabled:1;
132 
133 		u32		  probe_timestamp;
134 	} icsk_mtup;
135 	u32			  icsk_probes_tstamp;
136 	u32			  icsk_user_timeout;
137 
138 	u64			  icsk_ca_priv[104 / sizeof(u64)];
139 #define ICSK_CA_PRIV_SIZE	  sizeof_field(struct inet_connection_sock, icsk_ca_priv)
140 };
141 
142 #define ICSK_TIME_RETRANS	1	/* Retransmit timer */
143 #define ICSK_TIME_DACK		2	/* Delayed ack timer */
144 #define ICSK_TIME_PROBE0	3	/* Zero window probe timer */
145 #define ICSK_TIME_LOSS_PROBE	5	/* Tail loss probe timer */
146 #define ICSK_TIME_REO_TIMEOUT	6	/* Reordering timer */
147 
148 static inline struct inet_connection_sock *inet_csk(const struct sock *sk)
149 {
150 	return (struct inet_connection_sock *)sk;
151 }
152 
153 static inline void *inet_csk_ca(const struct sock *sk)
154 {
155 	return (void *)inet_csk(sk)->icsk_ca_priv;
156 }
157 
158 struct sock *inet_csk_clone_lock(const struct sock *sk,
159 				 const struct request_sock *req,
160 				 const gfp_t priority);
161 
162 enum inet_csk_ack_state_t {
163 	ICSK_ACK_SCHED	= 1,
164 	ICSK_ACK_TIMER  = 2,
165 	ICSK_ACK_PUSHED = 4,
166 	ICSK_ACK_PUSHED2 = 8,
167 	ICSK_ACK_NOW = 16	/* Send the next ACK immediately (once) */
168 };
169 
170 void inet_csk_init_xmit_timers(struct sock *sk,
171 			       void (*retransmit_handler)(struct timer_list *),
172 			       void (*delack_handler)(struct timer_list *),
173 			       void (*keepalive_handler)(struct timer_list *));
174 void inet_csk_clear_xmit_timers(struct sock *sk);
175 
176 static inline void inet_csk_schedule_ack(struct sock *sk)
177 {
178 	inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_SCHED;
179 }
180 
181 static inline int inet_csk_ack_scheduled(const struct sock *sk)
182 {
183 	return inet_csk(sk)->icsk_ack.pending & ICSK_ACK_SCHED;
184 }
185 
186 static inline void inet_csk_delack_init(struct sock *sk)
187 {
188 	memset(&inet_csk(sk)->icsk_ack, 0, sizeof(inet_csk(sk)->icsk_ack));
189 }
190 
191 void inet_csk_delete_keepalive_timer(struct sock *sk);
192 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long timeout);
193 
194 static inline void inet_csk_clear_xmit_timer(struct sock *sk, const int what)
195 {
196 	struct inet_connection_sock *icsk = inet_csk(sk);
197 
198 	if (what == ICSK_TIME_RETRANS || what == ICSK_TIME_PROBE0) {
199 		icsk->icsk_pending = 0;
200 #ifdef INET_CSK_CLEAR_TIMERS
201 		sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
202 #endif
203 	} else if (what == ICSK_TIME_DACK) {
204 		icsk->icsk_ack.pending = 0;
205 		icsk->icsk_ack.retry = 0;
206 #ifdef INET_CSK_CLEAR_TIMERS
207 		sk_stop_timer(sk, &icsk->icsk_delack_timer);
208 #endif
209 	} else {
210 		pr_debug("inet_csk BUG: unknown timer value\n");
211 	}
212 }
213 
214 /*
215  *	Reset the retransmission timer
216  */
217 static inline void inet_csk_reset_xmit_timer(struct sock *sk, const int what,
218 					     unsigned long when,
219 					     const unsigned long max_when)
220 {
221 	struct inet_connection_sock *icsk = inet_csk(sk);
222 
223 	if (when > max_when) {
224 		pr_debug("reset_xmit_timer: sk=%p %d when=0x%lx, caller=%p\n",
225 			 sk, what, when, (void *)_THIS_IP_);
226 		when = max_when;
227 	}
228 
229 	if (what == ICSK_TIME_RETRANS || what == ICSK_TIME_PROBE0 ||
230 	    what == ICSK_TIME_LOSS_PROBE || what == ICSK_TIME_REO_TIMEOUT) {
231 		icsk->icsk_pending = what;
232 		icsk->icsk_timeout = jiffies + when;
233 		sk_reset_timer(sk, &icsk->icsk_retransmit_timer, icsk->icsk_timeout);
234 	} else if (what == ICSK_TIME_DACK) {
235 		icsk->icsk_ack.pending |= ICSK_ACK_TIMER;
236 		icsk->icsk_ack.timeout = jiffies + when;
237 		sk_reset_timer(sk, &icsk->icsk_delack_timer, icsk->icsk_ack.timeout);
238 	} else {
239 		pr_debug("inet_csk BUG: unknown timer value\n");
240 	}
241 }
242 
243 static inline unsigned long
244 inet_csk_rto_backoff(const struct inet_connection_sock *icsk,
245 		     unsigned long max_when)
246 {
247         u64 when = (u64)icsk->icsk_rto << icsk->icsk_backoff;
248 
249         return (unsigned long)min_t(u64, when, max_when);
250 }
251 
252 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern);
253 
254 int inet_csk_get_port(struct sock *sk, unsigned short snum);
255 
256 struct dst_entry *inet_csk_route_req(const struct sock *sk, struct flowi4 *fl4,
257 				     const struct request_sock *req);
258 struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
259 					    struct sock *newsk,
260 					    const struct request_sock *req);
261 
262 struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
263 				      struct request_sock *req,
264 				      struct sock *child);
265 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
266 				   unsigned long timeout);
267 struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
268 					 struct request_sock *req,
269 					 bool own_req);
270 
271 static inline void inet_csk_reqsk_queue_added(struct sock *sk)
272 {
273 	reqsk_queue_added(&inet_csk(sk)->icsk_accept_queue);
274 }
275 
276 static inline int inet_csk_reqsk_queue_len(const struct sock *sk)
277 {
278 	return reqsk_queue_len(&inet_csk(sk)->icsk_accept_queue);
279 }
280 
281 static inline int inet_csk_reqsk_queue_is_full(const struct sock *sk)
282 {
283 	return inet_csk_reqsk_queue_len(sk) >= sk->sk_max_ack_backlog;
284 }
285 
286 bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req);
287 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req);
288 
289 static inline unsigned long
290 reqsk_timeout(struct request_sock *req, unsigned long max_timeout)
291 {
292 	u64 timeout = (u64)req->timeout << req->num_timeout;
293 
294 	return (unsigned long)min_t(u64, timeout, max_timeout);
295 }
296 
297 static inline void inet_csk_prepare_for_destroy_sock(struct sock *sk)
298 {
299 	/* The below has to be done to allow calling inet_csk_destroy_sock */
300 	sock_set_flag(sk, SOCK_DEAD);
301 	this_cpu_inc(*sk->sk_prot->orphan_count);
302 }
303 
304 void inet_csk_destroy_sock(struct sock *sk);
305 void inet_csk_prepare_forced_close(struct sock *sk);
306 
307 /*
308  * LISTEN is a special case for poll..
309  */
310 static inline __poll_t inet_csk_listen_poll(const struct sock *sk)
311 {
312 	return !reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue) ?
313 			(EPOLLIN | EPOLLRDNORM) : 0;
314 }
315 
316 int inet_csk_listen_start(struct sock *sk);
317 void inet_csk_listen_stop(struct sock *sk);
318 
319 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr);
320 
321 /* update the fast reuse flag when adding a socket */
322 void inet_csk_update_fastreuse(struct inet_bind_bucket *tb,
323 			       struct sock *sk);
324 
325 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu);
326 
327 #define TCP_PINGPONG_THRESH	1
328 
329 static inline void inet_csk_enter_pingpong_mode(struct sock *sk)
330 {
331 	inet_csk(sk)->icsk_ack.pingpong = TCP_PINGPONG_THRESH;
332 }
333 
334 static inline void inet_csk_exit_pingpong_mode(struct sock *sk)
335 {
336 	inet_csk(sk)->icsk_ack.pingpong = 0;
337 }
338 
339 static inline bool inet_csk_in_pingpong_mode(struct sock *sk)
340 {
341 	return inet_csk(sk)->icsk_ack.pingpong >= TCP_PINGPONG_THRESH;
342 }
343 
344 static inline bool inet_csk_has_ulp(struct sock *sk)
345 {
346 	return inet_sk(sk)->is_icsk && !!inet_csk(sk)->icsk_ulp_ops;
347 }
348 
349 #endif /* _INET_CONNECTION_SOCK_H */
350