xref: /openbmc/linux/include/net/tcp.h (revision 34d6f206a88c2651d216bd3487ac956a40b2ba8e)
1  /* SPDX-License-Identifier: GPL-2.0-or-later */
2  /*
3   * INET		An implementation of the TCP/IP protocol suite for the LINUX
4   *		operating system.  INET is implemented using the  BSD Socket
5   *		interface as the means of communication with the user level.
6   *
7   *		Definitions for the TCP module.
8   *
9   * Version:	@(#)tcp.h	1.0.5	05/23/93
10   *
11   * Authors:	Ross Biro
12   *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
13   */
14  #ifndef _TCP_H
15  #define _TCP_H
16  
17  #define FASTRETRANS_DEBUG 1
18  
19  #include <linux/list.h>
20  #include <linux/tcp.h>
21  #include <linux/bug.h>
22  #include <linux/slab.h>
23  #include <linux/cache.h>
24  #include <linux/percpu.h>
25  #include <linux/skbuff.h>
26  #include <linux/kref.h>
27  #include <linux/ktime.h>
28  #include <linux/indirect_call_wrapper.h>
29  
30  #include <net/inet_connection_sock.h>
31  #include <net/inet_timewait_sock.h>
32  #include <net/inet_hashtables.h>
33  #include <net/checksum.h>
34  #include <net/request_sock.h>
35  #include <net/sock_reuseport.h>
36  #include <net/sock.h>
37  #include <net/snmp.h>
38  #include <net/ip.h>
39  #include <net/tcp_states.h>
40  #include <net/inet_ecn.h>
41  #include <net/dst.h>
42  #include <net/mptcp.h>
43  
44  #include <linux/seq_file.h>
45  #include <linux/memcontrol.h>
46  #include <linux/bpf-cgroup.h>
47  #include <linux/siphash.h>
48  
49  extern struct inet_hashinfo tcp_hashinfo;
50  
51  DECLARE_PER_CPU(unsigned int, tcp_orphan_count);
52  int tcp_orphan_count_sum(void);
53  
54  void tcp_time_wait(struct sock *sk, int state, int timeo);
55  
56  #define MAX_TCP_HEADER	L1_CACHE_ALIGN(128 + MAX_HEADER)
57  #define MAX_TCP_OPTION_SPACE 40
58  #define TCP_MIN_SND_MSS		48
59  #define TCP_MIN_GSO_SIZE	(TCP_MIN_SND_MSS - MAX_TCP_OPTION_SPACE)
60  
61  /*
62   * Never offer a window over 32767 without using window scaling. Some
63   * poor stacks do signed 16bit maths!
64   */
65  #define MAX_TCP_WINDOW		32767U
66  
67  /* Minimal accepted MSS. It is (60+60+8) - (20+20). */
68  #define TCP_MIN_MSS		88U
69  
70  /* The initial MTU to use for probing */
71  #define TCP_BASE_MSS		1024
72  
73  /* probing interval, default to 10 minutes as per RFC4821 */
74  #define TCP_PROBE_INTERVAL	600
75  
76  /* Specify interval when tcp mtu probing will stop */
77  #define TCP_PROBE_THRESHOLD	8
78  
79  /* After receiving this amount of duplicate ACKs fast retransmit starts. */
80  #define TCP_FASTRETRANS_THRESH 3
81  
82  /* Maximal number of ACKs sent quickly to accelerate slow-start. */
83  #define TCP_MAX_QUICKACKS	16U
84  
85  /* Maximal number of window scale according to RFC1323 */
86  #define TCP_MAX_WSCALE		14U
87  
88  /* urg_data states */
89  #define TCP_URG_VALID	0x0100
90  #define TCP_URG_NOTYET	0x0200
91  #define TCP_URG_READ	0x0400
92  
93  #define TCP_RETR1	3	/*
94  				 * This is how many retries it does before it
95  				 * tries to figure out if the gateway is
96  				 * down. Minimal RFC value is 3; it corresponds
97  				 * to ~3sec-8min depending on RTO.
98  				 */
99  
100  #define TCP_RETR2	15	/*
101  				 * This should take at least
102  				 * 90 minutes to time out.
103  				 * RFC1122 says that the limit is 100 sec.
104  				 * 15 is ~13-30min depending on RTO.
105  				 */
106  
107  #define TCP_SYN_RETRIES	 6	/* This is how many retries are done
108  				 * when active opening a connection.
109  				 * RFC1122 says the minimum retry MUST
110  				 * be at least 180secs.  Nevertheless
111  				 * this value is corresponding to
112  				 * 63secs of retransmission with the
113  				 * current initial RTO.
114  				 */
115  
116  #define TCP_SYNACK_RETRIES 5	/* This is how may retries are done
117  				 * when passive opening a connection.
118  				 * This is corresponding to 31secs of
119  				 * retransmission with the current
120  				 * initial RTO.
121  				 */
122  
123  #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
124  				  * state, about 60 seconds	*/
125  #define TCP_FIN_TIMEOUT	TCP_TIMEWAIT_LEN
126                                   /* BSD style FIN_WAIT2 deadlock breaker.
127  				  * It used to be 3min, new value is 60sec,
128  				  * to combine FIN-WAIT-2 timeout with
129  				  * TIME-WAIT timer.
130  				  */
131  #define TCP_FIN_TIMEOUT_MAX (120 * HZ) /* max TCP_LINGER2 value (two minutes) */
132  
133  #define TCP_DELACK_MAX	((unsigned)(HZ/5))	/* maximal time to delay before sending an ACK */
134  #if HZ >= 100
135  #define TCP_DELACK_MIN	((unsigned)(HZ/25))	/* minimal time to delay before sending an ACK */
136  #define TCP_ATO_MIN	((unsigned)(HZ/25))
137  #else
138  #define TCP_DELACK_MIN	4U
139  #define TCP_ATO_MIN	4U
140  #endif
141  #define TCP_RTO_MAX	((unsigned)(120*HZ))
142  #define TCP_RTO_MIN	((unsigned)(HZ/5))
143  #define TCP_TIMEOUT_MIN	(2U) /* Min timeout for TCP timers in jiffies */
144  
145  #define TCP_TIMEOUT_MIN_US (2*USEC_PER_MSEC) /* Min TCP timeout in microsecs */
146  
147  #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ))	/* RFC6298 2.1 initial RTO value	*/
148  #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ))	/* RFC 1122 initial RTO value, now
149  						 * used as a fallback RTO for the
150  						 * initial data transmission if no
151  						 * valid RTT sample has been acquired,
152  						 * most likely due to retrans in 3WHS.
153  						 */
154  
155  #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
156  					                 * for local resources.
157  					                 */
158  #define TCP_KEEPALIVE_TIME	(120*60*HZ)	/* two hours */
159  #define TCP_KEEPALIVE_PROBES	9		/* Max of 9 keepalive probes	*/
160  #define TCP_KEEPALIVE_INTVL	(75*HZ)
161  
162  #define MAX_TCP_KEEPIDLE	32767
163  #define MAX_TCP_KEEPINTVL	32767
164  #define MAX_TCP_KEEPCNT		127
165  #define MAX_TCP_SYNCNT		127
166  
167  #define TCP_PAWS_24DAYS	(60 * 60 * 24 * 24)
168  #define TCP_PAWS_MSL	60		/* Per-host timestamps are invalidated
169  					 * after this time. It should be equal
170  					 * (or greater than) TCP_TIMEWAIT_LEN
171  					 * to provide reliability equal to one
172  					 * provided by timewait state.
173  					 */
174  #define TCP_PAWS_WINDOW	1		/* Replay window for per-host
175  					 * timestamps. It must be less than
176  					 * minimal timewait lifetime.
177  					 */
178  /*
179   *	TCP option
180   */
181  
182  #define TCPOPT_NOP		1	/* Padding */
183  #define TCPOPT_EOL		0	/* End of options */
184  #define TCPOPT_MSS		2	/* Segment size negotiating */
185  #define TCPOPT_WINDOW		3	/* Window scaling */
186  #define TCPOPT_SACK_PERM        4       /* SACK Permitted */
187  #define TCPOPT_SACK             5       /* SACK Block */
188  #define TCPOPT_TIMESTAMP	8	/* Better RTT estimations/PAWS */
189  #define TCPOPT_MD5SIG		19	/* MD5 Signature (RFC2385) */
190  #define TCPOPT_MPTCP		30	/* Multipath TCP (RFC6824) */
191  #define TCPOPT_FASTOPEN		34	/* Fast open (RFC7413) */
192  #define TCPOPT_EXP		254	/* Experimental */
193  /* Magic number to be after the option value for sharing TCP
194   * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
195   */
196  #define TCPOPT_FASTOPEN_MAGIC	0xF989
197  #define TCPOPT_SMC_MAGIC	0xE2D4C3D9
198  
199  /*
200   *     TCP option lengths
201   */
202  
203  #define TCPOLEN_MSS            4
204  #define TCPOLEN_WINDOW         3
205  #define TCPOLEN_SACK_PERM      2
206  #define TCPOLEN_TIMESTAMP      10
207  #define TCPOLEN_MD5SIG         18
208  #define TCPOLEN_FASTOPEN_BASE  2
209  #define TCPOLEN_EXP_FASTOPEN_BASE  4
210  #define TCPOLEN_EXP_SMC_BASE   6
211  
212  /* But this is what stacks really send out. */
213  #define TCPOLEN_TSTAMP_ALIGNED		12
214  #define TCPOLEN_WSCALE_ALIGNED		4
215  #define TCPOLEN_SACKPERM_ALIGNED	4
216  #define TCPOLEN_SACK_BASE		2
217  #define TCPOLEN_SACK_BASE_ALIGNED	4
218  #define TCPOLEN_SACK_PERBLOCK		8
219  #define TCPOLEN_MD5SIG_ALIGNED		20
220  #define TCPOLEN_MSS_ALIGNED		4
221  #define TCPOLEN_EXP_SMC_BASE_ALIGNED	8
222  
223  /* Flags in tp->nonagle */
224  #define TCP_NAGLE_OFF		1	/* Nagle's algo is disabled */
225  #define TCP_NAGLE_CORK		2	/* Socket is corked	    */
226  #define TCP_NAGLE_PUSH		4	/* Cork is overridden for already queued data */
227  
228  /* TCP thin-stream limits */
229  #define TCP_THIN_LINEAR_RETRIES 6       /* After 6 linear retries, do exp. backoff */
230  
231  /* TCP initial congestion window as per rfc6928 */
232  #define TCP_INIT_CWND		10
233  
234  /* Bit Flags for sysctl_tcp_fastopen */
235  #define	TFO_CLIENT_ENABLE	1
236  #define	TFO_SERVER_ENABLE	2
237  #define	TFO_CLIENT_NO_COOKIE	4	/* Data in SYN w/o cookie option */
238  
239  /* Accept SYN data w/o any cookie option */
240  #define	TFO_SERVER_COOKIE_NOT_REQD	0x200
241  
242  /* Force enable TFO on all listeners, i.e., not requiring the
243   * TCP_FASTOPEN socket option.
244   */
245  #define	TFO_SERVER_WO_SOCKOPT1	0x400
246  
247  
248  /* sysctl variables for tcp */
249  extern int sysctl_tcp_max_orphans;
250  extern long sysctl_tcp_mem[3];
251  
252  #define TCP_RACK_LOSS_DETECTION  0x1 /* Use RACK to detect losses */
253  #define TCP_RACK_STATIC_REO_WND  0x2 /* Use static RACK reo wnd */
254  #define TCP_RACK_NO_DUPTHRESH    0x4 /* Do not use DUPACK threshold in RACK */
255  
256  extern atomic_long_t tcp_memory_allocated;
257  DECLARE_PER_CPU(int, tcp_memory_per_cpu_fw_alloc);
258  
259  extern struct percpu_counter tcp_sockets_allocated;
260  extern unsigned long tcp_memory_pressure;
261  
262  /* optimized version of sk_under_memory_pressure() for TCP sockets */
tcp_under_memory_pressure(const struct sock * sk)263  static inline bool tcp_under_memory_pressure(const struct sock *sk)
264  {
265  	if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
266  	    mem_cgroup_under_socket_pressure(sk->sk_memcg))
267  		return true;
268  
269  	return READ_ONCE(tcp_memory_pressure);
270  }
271  /*
272   * The next routines deal with comparing 32 bit unsigned ints
273   * and worry about wraparound (automatic with unsigned arithmetic).
274   */
275  
before(__u32 seq1,__u32 seq2)276  static inline bool before(__u32 seq1, __u32 seq2)
277  {
278          return (__s32)(seq1-seq2) < 0;
279  }
280  #define after(seq2, seq1) 	before(seq1, seq2)
281  
282  /* is s2<=s1<=s3 ? */
between(__u32 seq1,__u32 seq2,__u32 seq3)283  static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
284  {
285  	return seq3 - seq2 >= seq1 - seq2;
286  }
287  
tcp_out_of_memory(struct sock * sk)288  static inline bool tcp_out_of_memory(struct sock *sk)
289  {
290  	if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
291  	    sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
292  		return true;
293  	return false;
294  }
295  
tcp_wmem_free_skb(struct sock * sk,struct sk_buff * skb)296  static inline void tcp_wmem_free_skb(struct sock *sk, struct sk_buff *skb)
297  {
298  	sk_wmem_queued_add(sk, -skb->truesize);
299  	if (!skb_zcopy_pure(skb))
300  		sk_mem_uncharge(sk, skb->truesize);
301  	else
302  		sk_mem_uncharge(sk, SKB_TRUESIZE(skb_end_offset(skb)));
303  	__kfree_skb(skb);
304  }
305  
306  void sk_forced_mem_schedule(struct sock *sk, int size);
307  
308  bool tcp_check_oom(struct sock *sk, int shift);
309  
310  
311  extern struct proto tcp_prot;
312  
313  #define TCP_INC_STATS(net, field)	SNMP_INC_STATS((net)->mib.tcp_statistics, field)
314  #define __TCP_INC_STATS(net, field)	__SNMP_INC_STATS((net)->mib.tcp_statistics, field)
315  #define TCP_DEC_STATS(net, field)	SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
316  #define TCP_ADD_STATS(net, field, val)	SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
317  
318  void tcp_tasklet_init(void);
319  
320  int tcp_v4_err(struct sk_buff *skb, u32);
321  
322  void tcp_shutdown(struct sock *sk, int how);
323  
324  int tcp_v4_early_demux(struct sk_buff *skb);
325  int tcp_v4_rcv(struct sk_buff *skb);
326  
327  void tcp_remove_empty_skb(struct sock *sk);
328  int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
329  int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size);
330  int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, int *copied,
331  			 size_t size, struct ubuf_info *uarg);
332  void tcp_splice_eof(struct socket *sock);
333  int tcp_send_mss(struct sock *sk, int *size_goal, int flags);
334  int tcp_wmem_schedule(struct sock *sk, int copy);
335  void tcp_push(struct sock *sk, int flags, int mss_now, int nonagle,
336  	      int size_goal);
337  void tcp_release_cb(struct sock *sk);
338  void tcp_wfree(struct sk_buff *skb);
339  void tcp_write_timer_handler(struct sock *sk);
340  void tcp_delack_timer_handler(struct sock *sk);
341  int tcp_ioctl(struct sock *sk, int cmd, int *karg);
342  int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
343  void tcp_rcv_established(struct sock *sk, struct sk_buff *skb);
344  void tcp_rcv_space_adjust(struct sock *sk);
345  int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
346  void tcp_twsk_destructor(struct sock *sk);
347  void tcp_twsk_purge(struct list_head *net_exit_list);
348  ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
349  			struct pipe_inode_info *pipe, size_t len,
350  			unsigned int flags);
351  struct sk_buff *tcp_stream_alloc_skb(struct sock *sk, gfp_t gfp,
352  				     bool force_schedule);
353  
tcp_dec_quickack_mode(struct sock * sk)354  static inline void tcp_dec_quickack_mode(struct sock *sk)
355  {
356  	struct inet_connection_sock *icsk = inet_csk(sk);
357  
358  	if (icsk->icsk_ack.quick) {
359  		/* How many ACKs S/ACKing new data have we sent? */
360  		const unsigned int pkts = inet_csk_ack_scheduled(sk) ? 1 : 0;
361  
362  		if (pkts >= icsk->icsk_ack.quick) {
363  			icsk->icsk_ack.quick = 0;
364  			/* Leaving quickack mode we deflate ATO. */
365  			icsk->icsk_ack.ato   = TCP_ATO_MIN;
366  		} else
367  			icsk->icsk_ack.quick -= pkts;
368  	}
369  }
370  
371  #define	TCP_ECN_OK		1
372  #define	TCP_ECN_QUEUE_CWR	2
373  #define	TCP_ECN_DEMAND_CWR	4
374  #define	TCP_ECN_SEEN		8
375  
376  enum tcp_tw_status {
377  	TCP_TW_SUCCESS = 0,
378  	TCP_TW_RST = 1,
379  	TCP_TW_ACK = 2,
380  	TCP_TW_SYN = 3
381  };
382  
383  
384  enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
385  					      struct sk_buff *skb,
386  					      const struct tcphdr *th);
387  struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
388  			   struct request_sock *req, bool fastopen,
389  			   bool *lost_race);
390  int tcp_child_process(struct sock *parent, struct sock *child,
391  		      struct sk_buff *skb);
392  void tcp_enter_loss(struct sock *sk);
393  void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int newly_lost, int flag);
394  void tcp_clear_retrans(struct tcp_sock *tp);
395  void tcp_update_metrics(struct sock *sk);
396  void tcp_init_metrics(struct sock *sk);
397  void tcp_metrics_init(void);
398  bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst);
399  void __tcp_close(struct sock *sk, long timeout);
400  void tcp_close(struct sock *sk, long timeout);
401  void tcp_init_sock(struct sock *sk);
402  void tcp_init_transfer(struct sock *sk, int bpf_op, struct sk_buff *skb);
403  __poll_t tcp_poll(struct file *file, struct socket *sock,
404  		      struct poll_table_struct *wait);
405  int do_tcp_getsockopt(struct sock *sk, int level,
406  		      int optname, sockptr_t optval, sockptr_t optlen);
407  int tcp_getsockopt(struct sock *sk, int level, int optname,
408  		   char __user *optval, int __user *optlen);
409  bool tcp_bpf_bypass_getsockopt(int level, int optname);
410  int do_tcp_setsockopt(struct sock *sk, int level, int optname,
411  		      sockptr_t optval, unsigned int optlen);
412  int tcp_setsockopt(struct sock *sk, int level, int optname, sockptr_t optval,
413  		   unsigned int optlen);
414  void tcp_set_keepalive(struct sock *sk, int val);
415  void tcp_syn_ack_timeout(const struct request_sock *req);
416  int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
417  		int flags, int *addr_len);
418  int tcp_set_rcvlowat(struct sock *sk, int val);
419  int tcp_set_window_clamp(struct sock *sk, int val);
420  void tcp_update_recv_tstamps(struct sk_buff *skb,
421  			     struct scm_timestamping_internal *tss);
422  void tcp_recv_timestamp(struct msghdr *msg, const struct sock *sk,
423  			struct scm_timestamping_internal *tss);
424  void tcp_data_ready(struct sock *sk);
425  #ifdef CONFIG_MMU
426  int tcp_mmap(struct file *file, struct socket *sock,
427  	     struct vm_area_struct *vma);
428  #endif
429  void tcp_parse_options(const struct net *net, const struct sk_buff *skb,
430  		       struct tcp_options_received *opt_rx,
431  		       int estab, struct tcp_fastopen_cookie *foc);
432  const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
433  
434  /*
435   *	BPF SKB-less helpers
436   */
437  u16 tcp_v4_get_syncookie(struct sock *sk, struct iphdr *iph,
438  			 struct tcphdr *th, u32 *cookie);
439  u16 tcp_v6_get_syncookie(struct sock *sk, struct ipv6hdr *iph,
440  			 struct tcphdr *th, u32 *cookie);
441  u16 tcp_parse_mss_option(const struct tcphdr *th, u16 user_mss);
442  u16 tcp_get_syncookie_mss(struct request_sock_ops *rsk_ops,
443  			  const struct tcp_request_sock_ops *af_ops,
444  			  struct sock *sk, struct tcphdr *th);
445  /*
446   *	TCP v4 functions exported for the inet6 API
447   */
448  
449  void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
450  void tcp_v4_mtu_reduced(struct sock *sk);
451  void tcp_req_err(struct sock *sk, u32 seq, bool abort);
452  void tcp_ld_RTO_revert(struct sock *sk, u32 seq);
453  int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
454  struct sock *tcp_create_openreq_child(const struct sock *sk,
455  				      struct request_sock *req,
456  				      struct sk_buff *skb);
457  void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
458  struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
459  				  struct request_sock *req,
460  				  struct dst_entry *dst,
461  				  struct request_sock *req_unhash,
462  				  bool *own_req);
463  int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
464  int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
465  int tcp_connect(struct sock *sk);
466  enum tcp_synack_type {
467  	TCP_SYNACK_NORMAL,
468  	TCP_SYNACK_FASTOPEN,
469  	TCP_SYNACK_COOKIE,
470  };
471  struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
472  				struct request_sock *req,
473  				struct tcp_fastopen_cookie *foc,
474  				enum tcp_synack_type synack_type,
475  				struct sk_buff *syn_skb);
476  int tcp_disconnect(struct sock *sk, int flags);
477  
478  void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
479  int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
480  void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
481  
482  /* From syncookies.c */
483  struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
484  				 struct request_sock *req,
485  				 struct dst_entry *dst, u32 tsoff);
486  int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
487  		      u32 cookie);
488  struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
489  struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops,
490  					    const struct tcp_request_sock_ops *af_ops,
491  					    struct sock *sk, struct sk_buff *skb);
492  #ifdef CONFIG_SYN_COOKIES
493  
494  /* Syncookies use a monotonic timer which increments every 60 seconds.
495   * This counter is used both as a hash input and partially encoded into
496   * the cookie value.  A cookie is only validated further if the delta
497   * between the current counter value and the encoded one is less than this,
498   * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
499   * the counter advances immediately after a cookie is generated).
500   */
501  #define MAX_SYNCOOKIE_AGE	2
502  #define TCP_SYNCOOKIE_PERIOD	(60 * HZ)
503  #define TCP_SYNCOOKIE_VALID	(MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
504  
505  /* syncookies: remember time of last synqueue overflow
506   * But do not dirty this field too often (once per second is enough)
507   * It is racy as we do not hold a lock, but race is very minor.
508   */
tcp_synq_overflow(const struct sock * sk)509  static inline void tcp_synq_overflow(const struct sock *sk)
510  {
511  	unsigned int last_overflow;
512  	unsigned int now = jiffies;
513  
514  	if (sk->sk_reuseport) {
515  		struct sock_reuseport *reuse;
516  
517  		reuse = rcu_dereference(sk->sk_reuseport_cb);
518  		if (likely(reuse)) {
519  			last_overflow = READ_ONCE(reuse->synq_overflow_ts);
520  			if (!time_between32(now, last_overflow,
521  					    last_overflow + HZ))
522  				WRITE_ONCE(reuse->synq_overflow_ts, now);
523  			return;
524  		}
525  	}
526  
527  	last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
528  	if (!time_between32(now, last_overflow, last_overflow + HZ))
529  		WRITE_ONCE(tcp_sk_rw(sk)->rx_opt.ts_recent_stamp, now);
530  }
531  
532  /* syncookies: no recent synqueue overflow on this listening socket? */
tcp_synq_no_recent_overflow(const struct sock * sk)533  static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
534  {
535  	unsigned int last_overflow;
536  	unsigned int now = jiffies;
537  
538  	if (sk->sk_reuseport) {
539  		struct sock_reuseport *reuse;
540  
541  		reuse = rcu_dereference(sk->sk_reuseport_cb);
542  		if (likely(reuse)) {
543  			last_overflow = READ_ONCE(reuse->synq_overflow_ts);
544  			return !time_between32(now, last_overflow - HZ,
545  					       last_overflow +
546  					       TCP_SYNCOOKIE_VALID);
547  		}
548  	}
549  
550  	last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
551  
552  	/* If last_overflow <= jiffies <= last_overflow + TCP_SYNCOOKIE_VALID,
553  	 * then we're under synflood. However, we have to use
554  	 * 'last_overflow - HZ' as lower bound. That's because a concurrent
555  	 * tcp_synq_overflow() could update .ts_recent_stamp after we read
556  	 * jiffies but before we store .ts_recent_stamp into last_overflow,
557  	 * which could lead to rejecting a valid syncookie.
558  	 */
559  	return !time_between32(now, last_overflow - HZ,
560  			       last_overflow + TCP_SYNCOOKIE_VALID);
561  }
562  
tcp_cookie_time(void)563  static inline u32 tcp_cookie_time(void)
564  {
565  	u64 val = get_jiffies_64();
566  
567  	do_div(val, TCP_SYNCOOKIE_PERIOD);
568  	return val;
569  }
570  
571  u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
572  			      u16 *mssp);
573  __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
574  u64 cookie_init_timestamp(struct request_sock *req, u64 now);
575  bool cookie_timestamp_decode(const struct net *net,
576  			     struct tcp_options_received *opt);
577  bool cookie_ecn_ok(const struct tcp_options_received *opt,
578  		   const struct net *net, const struct dst_entry *dst);
579  
580  /* From net/ipv6/syncookies.c */
581  int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
582  		      u32 cookie);
583  struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
584  
585  u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
586  			      const struct tcphdr *th, u16 *mssp);
587  __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
588  #endif
589  /* tcp_output.c */
590  
591  void tcp_skb_entail(struct sock *sk, struct sk_buff *skb);
592  void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb);
593  void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
594  			       int nonagle);
595  int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
596  int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
597  void tcp_retransmit_timer(struct sock *sk);
598  void tcp_xmit_retransmit_queue(struct sock *);
599  void tcp_simple_retransmit(struct sock *);
600  void tcp_enter_recovery(struct sock *sk, bool ece_ack);
601  int tcp_trim_head(struct sock *, struct sk_buff *, u32);
602  enum tcp_queue {
603  	TCP_FRAG_IN_WRITE_QUEUE,
604  	TCP_FRAG_IN_RTX_QUEUE,
605  };
606  int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
607  		 struct sk_buff *skb, u32 len,
608  		 unsigned int mss_now, gfp_t gfp);
609  
610  void tcp_send_probe0(struct sock *);
611  int tcp_write_wakeup(struct sock *, int mib);
612  void tcp_send_fin(struct sock *sk);
613  void tcp_send_active_reset(struct sock *sk, gfp_t priority);
614  int tcp_send_synack(struct sock *);
615  void tcp_push_one(struct sock *, unsigned int mss_now);
616  void __tcp_send_ack(struct sock *sk, u32 rcv_nxt);
617  void tcp_send_ack(struct sock *sk);
618  void tcp_send_delayed_ack(struct sock *sk);
619  void tcp_send_loss_probe(struct sock *sk);
620  bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto);
621  void tcp_skb_collapse_tstamp(struct sk_buff *skb,
622  			     const struct sk_buff *next_skb);
623  
624  /* tcp_input.c */
625  void tcp_rearm_rto(struct sock *sk);
626  void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
627  void tcp_done_with_error(struct sock *sk, int err);
628  void tcp_reset(struct sock *sk, struct sk_buff *skb);
629  void tcp_fin(struct sock *sk);
630  void tcp_check_space(struct sock *sk);
631  void tcp_sack_compress_send_ack(struct sock *sk);
632  
633  /* tcp_timer.c */
634  void tcp_init_xmit_timers(struct sock *);
tcp_clear_xmit_timers(struct sock * sk)635  static inline void tcp_clear_xmit_timers(struct sock *sk)
636  {
637  	if (hrtimer_try_to_cancel(&tcp_sk(sk)->pacing_timer) == 1)
638  		__sock_put(sk);
639  
640  	if (hrtimer_try_to_cancel(&tcp_sk(sk)->compressed_ack_timer) == 1)
641  		__sock_put(sk);
642  
643  	inet_csk_clear_xmit_timers(sk);
644  }
645  
646  unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
647  unsigned int tcp_current_mss(struct sock *sk);
648  u32 tcp_clamp_probe0_to_user_timeout(const struct sock *sk, u32 when);
649  
650  /* Bound MSS / TSO packet size with the half of the window */
tcp_bound_to_half_wnd(struct tcp_sock * tp,int pktsize)651  static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
652  {
653  	int cutoff;
654  
655  	/* When peer uses tiny windows, there is no use in packetizing
656  	 * to sub-MSS pieces for the sake of SWS or making sure there
657  	 * are enough packets in the pipe for fast recovery.
658  	 *
659  	 * On the other hand, for extremely large MSS devices, handling
660  	 * smaller than MSS windows in this way does make sense.
661  	 */
662  	if (tp->max_window > TCP_MSS_DEFAULT)
663  		cutoff = (tp->max_window >> 1);
664  	else
665  		cutoff = tp->max_window;
666  
667  	if (cutoff && pktsize > cutoff)
668  		return max_t(int, cutoff, 68U - tp->tcp_header_len);
669  	else
670  		return pktsize;
671  }
672  
673  /* tcp.c */
674  void tcp_get_info(struct sock *, struct tcp_info *);
675  
676  /* Read 'sendfile()'-style from a TCP socket */
677  int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
678  		  sk_read_actor_t recv_actor);
679  int tcp_read_skb(struct sock *sk, skb_read_actor_t recv_actor);
680  struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off);
681  void tcp_read_done(struct sock *sk, size_t len);
682  
683  void tcp_initialize_rcv_mss(struct sock *sk);
684  
685  int tcp_mtu_to_mss(struct sock *sk, int pmtu);
686  int tcp_mss_to_mtu(struct sock *sk, int mss);
687  void tcp_mtup_init(struct sock *sk);
688  
tcp_bound_rto(const struct sock * sk)689  static inline void tcp_bound_rto(const struct sock *sk)
690  {
691  	if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
692  		inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
693  }
694  
__tcp_set_rto(const struct tcp_sock * tp)695  static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
696  {
697  	return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
698  }
699  
__tcp_fast_path_on(struct tcp_sock * tp,u32 snd_wnd)700  static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
701  {
702  	/* mptcp hooks are only on the slow path */
703  	if (sk_is_mptcp((struct sock *)tp))
704  		return;
705  
706  	tp->pred_flags = htonl((tp->tcp_header_len << 26) |
707  			       ntohl(TCP_FLAG_ACK) |
708  			       snd_wnd);
709  }
710  
tcp_fast_path_on(struct tcp_sock * tp)711  static inline void tcp_fast_path_on(struct tcp_sock *tp)
712  {
713  	__tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
714  }
715  
tcp_fast_path_check(struct sock * sk)716  static inline void tcp_fast_path_check(struct sock *sk)
717  {
718  	struct tcp_sock *tp = tcp_sk(sk);
719  
720  	if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
721  	    tp->rcv_wnd &&
722  	    atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
723  	    !tp->urg_data)
724  		tcp_fast_path_on(tp);
725  }
726  
727  u32 tcp_delack_max(const struct sock *sk);
728  
729  /* Compute the actual rto_min value */
tcp_rto_min(struct sock * sk)730  static inline u32 tcp_rto_min(struct sock *sk)
731  {
732  	const struct dst_entry *dst = __sk_dst_get(sk);
733  	u32 rto_min = inet_csk(sk)->icsk_rto_min;
734  
735  	if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
736  		rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
737  	return rto_min;
738  }
739  
tcp_rto_min_us(struct sock * sk)740  static inline u32 tcp_rto_min_us(struct sock *sk)
741  {
742  	return jiffies_to_usecs(tcp_rto_min(sk));
743  }
744  
tcp_ca_dst_locked(const struct dst_entry * dst)745  static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
746  {
747  	return dst_metric_locked(dst, RTAX_CC_ALGO);
748  }
749  
750  /* Minimum RTT in usec. ~0 means not available. */
tcp_min_rtt(const struct tcp_sock * tp)751  static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
752  {
753  	return minmax_get(&tp->rtt_min);
754  }
755  
756  /* Compute the actual receive window we are currently advertising.
757   * Rcv_nxt can be after the window if our peer push more data
758   * than the offered window.
759   */
tcp_receive_window(const struct tcp_sock * tp)760  static inline u32 tcp_receive_window(const struct tcp_sock *tp)
761  {
762  	s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
763  
764  	if (win < 0)
765  		win = 0;
766  	return (u32) win;
767  }
768  
769  /* Choose a new window, without checks for shrinking, and without
770   * scaling applied to the result.  The caller does these things
771   * if necessary.  This is a "raw" window selection.
772   */
773  u32 __tcp_select_window(struct sock *sk);
774  
775  void tcp_send_window_probe(struct sock *sk);
776  
777  /* TCP uses 32bit jiffies to save some space.
778   * Note that this is different from tcp_time_stamp, which
779   * historically has been the same until linux-4.13.
780   */
781  #define tcp_jiffies32 ((u32)jiffies)
782  
783  /*
784   * Deliver a 32bit value for TCP timestamp option (RFC 7323)
785   * It is no longer tied to jiffies, but to 1 ms clock.
786   * Note: double check if you want to use tcp_jiffies32 instead of this.
787   */
788  #define TCP_TS_HZ	1000
789  
tcp_clock_ns(void)790  static inline u64 tcp_clock_ns(void)
791  {
792  	return ktime_get_ns();
793  }
794  
tcp_clock_us(void)795  static inline u64 tcp_clock_us(void)
796  {
797  	return div_u64(tcp_clock_ns(), NSEC_PER_USEC);
798  }
799  
800  /* This should only be used in contexts where tp->tcp_mstamp is up to date */
tcp_time_stamp(const struct tcp_sock * tp)801  static inline u32 tcp_time_stamp(const struct tcp_sock *tp)
802  {
803  	return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ);
804  }
805  
806  /* Convert a nsec timestamp into TCP TSval timestamp (ms based currently) */
tcp_ns_to_ts(u64 ns)807  static inline u64 tcp_ns_to_ts(u64 ns)
808  {
809  	return div_u64(ns, NSEC_PER_SEC / TCP_TS_HZ);
810  }
811  
812  /* Could use tcp_clock_us() / 1000, but this version uses a single divide */
tcp_time_stamp_raw(void)813  static inline u32 tcp_time_stamp_raw(void)
814  {
815  	return tcp_ns_to_ts(tcp_clock_ns());
816  }
817  
818  void tcp_mstamp_refresh(struct tcp_sock *tp);
819  
tcp_stamp_us_delta(u64 t1,u64 t0)820  static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
821  {
822  	return max_t(s64, t1 - t0, 0);
823  }
824  
tcp_skb_timestamp(const struct sk_buff * skb)825  static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
826  {
827  	return tcp_ns_to_ts(skb->skb_mstamp_ns);
828  }
829  
830  /* provide the departure time in us unit */
tcp_skb_timestamp_us(const struct sk_buff * skb)831  static inline u64 tcp_skb_timestamp_us(const struct sk_buff *skb)
832  {
833  	return div_u64(skb->skb_mstamp_ns, NSEC_PER_USEC);
834  }
835  
836  
837  #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
838  
839  #define TCPHDR_FIN 0x01
840  #define TCPHDR_SYN 0x02
841  #define TCPHDR_RST 0x04
842  #define TCPHDR_PSH 0x08
843  #define TCPHDR_ACK 0x10
844  #define TCPHDR_URG 0x20
845  #define TCPHDR_ECE 0x40
846  #define TCPHDR_CWR 0x80
847  
848  #define TCPHDR_SYN_ECN	(TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
849  
850  /* This is what the send packet queuing engine uses to pass
851   * TCP per-packet control information to the transmission code.
852   * We also store the host-order sequence numbers in here too.
853   * This is 44 bytes if IPV6 is enabled.
854   * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
855   */
856  struct tcp_skb_cb {
857  	__u32		seq;		/* Starting sequence number	*/
858  	__u32		end_seq;	/* SEQ + FIN + SYN + datalen	*/
859  	union {
860  		/* Note : tcp_tw_isn is used in input path only
861  		 *	  (isn chosen by tcp_timewait_state_process())
862  		 *
863  		 * 	  tcp_gso_segs/size are used in write queue only,
864  		 *	  cf tcp_skb_pcount()/tcp_skb_mss()
865  		 */
866  		__u32		tcp_tw_isn;
867  		struct {
868  			u16	tcp_gso_segs;
869  			u16	tcp_gso_size;
870  		};
871  	};
872  	__u8		tcp_flags;	/* TCP header flags. (tcp[13])	*/
873  
874  	__u8		sacked;		/* State flags for SACK.	*/
875  #define TCPCB_SACKED_ACKED	0x01	/* SKB ACK'd by a SACK block	*/
876  #define TCPCB_SACKED_RETRANS	0x02	/* SKB retransmitted		*/
877  #define TCPCB_LOST		0x04	/* SKB is lost			*/
878  #define TCPCB_TAGBITS		0x07	/* All tag bits			*/
879  #define TCPCB_REPAIRED		0x10	/* SKB repaired (no skb_mstamp_ns)	*/
880  #define TCPCB_EVER_RETRANS	0x80	/* Ever retransmitted frame	*/
881  #define TCPCB_RETRANS		(TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
882  				TCPCB_REPAIRED)
883  
884  	__u8		ip_dsfield;	/* IPv4 tos or IPv6 dsfield	*/
885  	__u8		txstamp_ack:1,	/* Record TX timestamp for ack? */
886  			eor:1,		/* Is skb MSG_EOR marked? */
887  			has_rxtstamp:1,	/* SKB has a RX timestamp	*/
888  			unused:5;
889  	__u32		ack_seq;	/* Sequence number ACK'd	*/
890  	union {
891  		struct {
892  #define TCPCB_DELIVERED_CE_MASK ((1U<<20) - 1)
893  			/* There is space for up to 24 bytes */
894  			__u32 is_app_limited:1, /* cwnd not fully used? */
895  			      delivered_ce:20,
896  			      unused:11;
897  			/* pkts S/ACKed so far upon tx of skb, incl retrans: */
898  			__u32 delivered;
899  			/* start of send pipeline phase */
900  			u64 first_tx_mstamp;
901  			/* when we reached the "delivered" count */
902  			u64 delivered_mstamp;
903  		} tx;   /* only used for outgoing skbs */
904  		union {
905  			struct inet_skb_parm	h4;
906  #if IS_ENABLED(CONFIG_IPV6)
907  			struct inet6_skb_parm	h6;
908  #endif
909  		} header;	/* For incoming skbs */
910  	};
911  };
912  
913  #define TCP_SKB_CB(__skb)	((struct tcp_skb_cb *)&((__skb)->cb[0]))
914  
915  extern const struct inet_connection_sock_af_ops ipv4_specific;
916  
917  #if IS_ENABLED(CONFIG_IPV6)
918  /* This is the variant of inet6_iif() that must be used by TCP,
919   * as TCP moves IP6CB into a different location in skb->cb[]
920   */
tcp_v6_iif(const struct sk_buff * skb)921  static inline int tcp_v6_iif(const struct sk_buff *skb)
922  {
923  	return TCP_SKB_CB(skb)->header.h6.iif;
924  }
925  
tcp_v6_iif_l3_slave(const struct sk_buff * skb)926  static inline int tcp_v6_iif_l3_slave(const struct sk_buff *skb)
927  {
928  	bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
929  
930  	return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
931  }
932  
933  /* TCP_SKB_CB reference means this can not be used from early demux */
tcp_v6_sdif(const struct sk_buff * skb)934  static inline int tcp_v6_sdif(const struct sk_buff *skb)
935  {
936  #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
937  	if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags))
938  		return TCP_SKB_CB(skb)->header.h6.iif;
939  #endif
940  	return 0;
941  }
942  
943  extern const struct inet_connection_sock_af_ops ipv6_specific;
944  
945  INDIRECT_CALLABLE_DECLARE(void tcp_v6_send_check(struct sock *sk, struct sk_buff *skb));
946  INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff *skb));
947  void tcp_v6_early_demux(struct sk_buff *skb);
948  
949  #endif
950  
951  /* TCP_SKB_CB reference means this can not be used from early demux */
tcp_v4_sdif(struct sk_buff * skb)952  static inline int tcp_v4_sdif(struct sk_buff *skb)
953  {
954  #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
955  	if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
956  		return TCP_SKB_CB(skb)->header.h4.iif;
957  #endif
958  	return 0;
959  }
960  
961  /* Due to TSO, an SKB can be composed of multiple actual
962   * packets.  To keep these tracked properly, we use this.
963   */
tcp_skb_pcount(const struct sk_buff * skb)964  static inline int tcp_skb_pcount(const struct sk_buff *skb)
965  {
966  	return TCP_SKB_CB(skb)->tcp_gso_segs;
967  }
968  
tcp_skb_pcount_set(struct sk_buff * skb,int segs)969  static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
970  {
971  	TCP_SKB_CB(skb)->tcp_gso_segs = segs;
972  }
973  
tcp_skb_pcount_add(struct sk_buff * skb,int segs)974  static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
975  {
976  	TCP_SKB_CB(skb)->tcp_gso_segs += segs;
977  }
978  
979  /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
tcp_skb_mss(const struct sk_buff * skb)980  static inline int tcp_skb_mss(const struct sk_buff *skb)
981  {
982  	return TCP_SKB_CB(skb)->tcp_gso_size;
983  }
984  
tcp_skb_can_collapse_to(const struct sk_buff * skb)985  static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
986  {
987  	return likely(!TCP_SKB_CB(skb)->eor);
988  }
989  
tcp_skb_can_collapse(const struct sk_buff * to,const struct sk_buff * from)990  static inline bool tcp_skb_can_collapse(const struct sk_buff *to,
991  					const struct sk_buff *from)
992  {
993  	return likely(tcp_skb_can_collapse_to(to) &&
994  		      mptcp_skb_can_collapse(to, from) &&
995  		      skb_pure_zcopy_same(to, from));
996  }
997  
998  /* Events passed to congestion control interface */
999  enum tcp_ca_event {
1000  	CA_EVENT_TX_START,	/* first transmit when no packets in flight */
1001  	CA_EVENT_CWND_RESTART,	/* congestion window restart */
1002  	CA_EVENT_COMPLETE_CWR,	/* end of congestion recovery */
1003  	CA_EVENT_LOSS,		/* loss timeout */
1004  	CA_EVENT_ECN_NO_CE,	/* ECT set, but not CE marked */
1005  	CA_EVENT_ECN_IS_CE,	/* received CE marked IP packet */
1006  };
1007  
1008  /* Information about inbound ACK, passed to cong_ops->in_ack_event() */
1009  enum tcp_ca_ack_event_flags {
1010  	CA_ACK_SLOWPATH		= (1 << 0),	/* In slow path processing */
1011  	CA_ACK_WIN_UPDATE	= (1 << 1),	/* ACK updated window */
1012  	CA_ACK_ECE		= (1 << 2),	/* ECE bit is set on ack */
1013  };
1014  
1015  /*
1016   * Interface for adding new TCP congestion control handlers
1017   */
1018  #define TCP_CA_NAME_MAX	16
1019  #define TCP_CA_MAX	128
1020  #define TCP_CA_BUF_MAX	(TCP_CA_NAME_MAX*TCP_CA_MAX)
1021  
1022  #define TCP_CA_UNSPEC	0
1023  
1024  /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
1025  #define TCP_CONG_NON_RESTRICTED 0x1
1026  /* Requires ECN/ECT set on all packets */
1027  #define TCP_CONG_NEEDS_ECN	0x2
1028  #define TCP_CONG_MASK	(TCP_CONG_NON_RESTRICTED | TCP_CONG_NEEDS_ECN)
1029  
1030  union tcp_cc_info;
1031  
1032  struct ack_sample {
1033  	u32 pkts_acked;
1034  	s32 rtt_us;
1035  	u32 in_flight;
1036  };
1037  
1038  /* A rate sample measures the number of (original/retransmitted) data
1039   * packets delivered "delivered" over an interval of time "interval_us".
1040   * The tcp_rate.c code fills in the rate sample, and congestion
1041   * control modules that define a cong_control function to run at the end
1042   * of ACK processing can optionally chose to consult this sample when
1043   * setting cwnd and pacing rate.
1044   * A sample is invalid if "delivered" or "interval_us" is negative.
1045   */
1046  struct rate_sample {
1047  	u64  prior_mstamp; /* starting timestamp for interval */
1048  	u32  prior_delivered;	/* tp->delivered at "prior_mstamp" */
1049  	u32  prior_delivered_ce;/* tp->delivered_ce at "prior_mstamp" */
1050  	s32  delivered;		/* number of packets delivered over interval */
1051  	s32  delivered_ce;	/* number of packets delivered w/ CE marks*/
1052  	long interval_us;	/* time for tp->delivered to incr "delivered" */
1053  	u32 snd_interval_us;	/* snd interval for delivered packets */
1054  	u32 rcv_interval_us;	/* rcv interval for delivered packets */
1055  	long rtt_us;		/* RTT of last (S)ACKed packet (or -1) */
1056  	int  losses;		/* number of packets marked lost upon ACK */
1057  	u32  acked_sacked;	/* number of packets newly (S)ACKed upon ACK */
1058  	u32  prior_in_flight;	/* in flight before this ACK */
1059  	u32  last_end_seq;	/* end_seq of most recently ACKed packet */
1060  	bool is_app_limited;	/* is sample from packet with bubble in pipe? */
1061  	bool is_retrans;	/* is sample from retransmission? */
1062  	bool is_ack_delayed;	/* is this (likely) a delayed ACK? */
1063  };
1064  
1065  struct tcp_congestion_ops {
1066  /* fast path fields are put first to fill one cache line */
1067  
1068  	/* return slow start threshold (required) */
1069  	u32 (*ssthresh)(struct sock *sk);
1070  
1071  	/* do new cwnd calculation (required) */
1072  	void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
1073  
1074  	/* call before changing ca_state (optional) */
1075  	void (*set_state)(struct sock *sk, u8 new_state);
1076  
1077  	/* call when cwnd event occurs (optional) */
1078  	void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
1079  
1080  	/* call when ack arrives (optional) */
1081  	void (*in_ack_event)(struct sock *sk, u32 flags);
1082  
1083  	/* hook for packet ack accounting (optional) */
1084  	void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
1085  
1086  	/* override sysctl_tcp_min_tso_segs */
1087  	u32 (*min_tso_segs)(struct sock *sk);
1088  
1089  	/* call when packets are delivered to update cwnd and pacing rate,
1090  	 * after all the ca_state processing. (optional)
1091  	 */
1092  	void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
1093  
1094  
1095  	/* new value of cwnd after loss (required) */
1096  	u32  (*undo_cwnd)(struct sock *sk);
1097  	/* returns the multiplier used in tcp_sndbuf_expand (optional) */
1098  	u32 (*sndbuf_expand)(struct sock *sk);
1099  
1100  /* control/slow paths put last */
1101  	/* get info for inet_diag (optional) */
1102  	size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
1103  			   union tcp_cc_info *info);
1104  
1105  	char 			name[TCP_CA_NAME_MAX];
1106  	struct module		*owner;
1107  	struct list_head	list;
1108  	u32			key;
1109  	u32			flags;
1110  
1111  	/* initialize private data (optional) */
1112  	void (*init)(struct sock *sk);
1113  	/* cleanup private data  (optional) */
1114  	void (*release)(struct sock *sk);
1115  } ____cacheline_aligned_in_smp;
1116  
1117  int tcp_register_congestion_control(struct tcp_congestion_ops *type);
1118  void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
1119  int tcp_update_congestion_control(struct tcp_congestion_ops *type,
1120  				  struct tcp_congestion_ops *old_type);
1121  int tcp_validate_congestion_control(struct tcp_congestion_ops *ca);
1122  
1123  void tcp_assign_congestion_control(struct sock *sk);
1124  void tcp_init_congestion_control(struct sock *sk);
1125  void tcp_cleanup_congestion_control(struct sock *sk);
1126  int tcp_set_default_congestion_control(struct net *net, const char *name);
1127  void tcp_get_default_congestion_control(struct net *net, char *name);
1128  void tcp_get_available_congestion_control(char *buf, size_t len);
1129  void tcp_get_allowed_congestion_control(char *buf, size_t len);
1130  int tcp_set_allowed_congestion_control(char *allowed);
1131  int tcp_set_congestion_control(struct sock *sk, const char *name, bool load,
1132  			       bool cap_net_admin);
1133  u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
1134  void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
1135  
1136  u32 tcp_reno_ssthresh(struct sock *sk);
1137  u32 tcp_reno_undo_cwnd(struct sock *sk);
1138  void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
1139  extern struct tcp_congestion_ops tcp_reno;
1140  
1141  struct tcp_congestion_ops *tcp_ca_find(const char *name);
1142  struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
1143  u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca);
1144  #ifdef CONFIG_INET
1145  char *tcp_ca_get_name_by_key(u32 key, char *buffer);
1146  #else
tcp_ca_get_name_by_key(u32 key,char * buffer)1147  static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
1148  {
1149  	return NULL;
1150  }
1151  #endif
1152  
tcp_ca_needs_ecn(const struct sock * sk)1153  static inline bool tcp_ca_needs_ecn(const struct sock *sk)
1154  {
1155  	const struct inet_connection_sock *icsk = inet_csk(sk);
1156  
1157  	return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
1158  }
1159  
tcp_ca_event(struct sock * sk,const enum tcp_ca_event event)1160  static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
1161  {
1162  	const struct inet_connection_sock *icsk = inet_csk(sk);
1163  
1164  	if (icsk->icsk_ca_ops->cwnd_event)
1165  		icsk->icsk_ca_ops->cwnd_event(sk, event);
1166  }
1167  
1168  /* From tcp_cong.c */
1169  void tcp_set_ca_state(struct sock *sk, const u8 ca_state);
1170  
1171  /* From tcp_rate.c */
1172  void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
1173  void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
1174  			    struct rate_sample *rs);
1175  void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1176  		  bool is_sack_reneg, struct rate_sample *rs);
1177  void tcp_rate_check_app_limited(struct sock *sk);
1178  
tcp_skb_sent_after(u64 t1,u64 t2,u32 seq1,u32 seq2)1179  static inline bool tcp_skb_sent_after(u64 t1, u64 t2, u32 seq1, u32 seq2)
1180  {
1181  	return t1 > t2 || (t1 == t2 && after(seq1, seq2));
1182  }
1183  
1184  /* These functions determine how the current flow behaves in respect of SACK
1185   * handling. SACK is negotiated with the peer, and therefore it can vary
1186   * between different flows.
1187   *
1188   * tcp_is_sack - SACK enabled
1189   * tcp_is_reno - No SACK
1190   */
tcp_is_sack(const struct tcp_sock * tp)1191  static inline int tcp_is_sack(const struct tcp_sock *tp)
1192  {
1193  	return likely(tp->rx_opt.sack_ok);
1194  }
1195  
tcp_is_reno(const struct tcp_sock * tp)1196  static inline bool tcp_is_reno(const struct tcp_sock *tp)
1197  {
1198  	return !tcp_is_sack(tp);
1199  }
1200  
tcp_left_out(const struct tcp_sock * tp)1201  static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
1202  {
1203  	return tp->sacked_out + tp->lost_out;
1204  }
1205  
1206  /* This determines how many packets are "in the network" to the best
1207   * of our knowledge.  In many cases it is conservative, but where
1208   * detailed information is available from the receiver (via SACK
1209   * blocks etc.) we can make more aggressive calculations.
1210   *
1211   * Use this for decisions involving congestion control, use just
1212   * tp->packets_out to determine if the send queue is empty or not.
1213   *
1214   * Read this equation as:
1215   *
1216   *	"Packets sent once on transmission queue" MINUS
1217   *	"Packets left network, but not honestly ACKed yet" PLUS
1218   *	"Packets fast retransmitted"
1219   */
tcp_packets_in_flight(const struct tcp_sock * tp)1220  static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1221  {
1222  	return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
1223  }
1224  
1225  #define TCP_INFINITE_SSTHRESH	0x7fffffff
1226  
tcp_snd_cwnd(const struct tcp_sock * tp)1227  static inline u32 tcp_snd_cwnd(const struct tcp_sock *tp)
1228  {
1229  	return tp->snd_cwnd;
1230  }
1231  
tcp_snd_cwnd_set(struct tcp_sock * tp,u32 val)1232  static inline void tcp_snd_cwnd_set(struct tcp_sock *tp, u32 val)
1233  {
1234  	WARN_ON_ONCE((int)val <= 0);
1235  	tp->snd_cwnd = val;
1236  }
1237  
tcp_in_slow_start(const struct tcp_sock * tp)1238  static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
1239  {
1240  	return tcp_snd_cwnd(tp) < tp->snd_ssthresh;
1241  }
1242  
tcp_in_initial_slowstart(const struct tcp_sock * tp)1243  static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1244  {
1245  	return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1246  }
1247  
tcp_in_cwnd_reduction(const struct sock * sk)1248  static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1249  {
1250  	return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1251  	       (1 << inet_csk(sk)->icsk_ca_state);
1252  }
1253  
1254  /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1255   * The exception is cwnd reduction phase, when cwnd is decreasing towards
1256   * ssthresh.
1257   */
tcp_current_ssthresh(const struct sock * sk)1258  static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1259  {
1260  	const struct tcp_sock *tp = tcp_sk(sk);
1261  
1262  	if (tcp_in_cwnd_reduction(sk))
1263  		return tp->snd_ssthresh;
1264  	else
1265  		return max(tp->snd_ssthresh,
1266  			   ((tcp_snd_cwnd(tp) >> 1) +
1267  			    (tcp_snd_cwnd(tp) >> 2)));
1268  }
1269  
1270  /* Use define here intentionally to get WARN_ON location shown at the caller */
1271  #define tcp_verify_left_out(tp)	WARN_ON(tcp_left_out(tp) > tp->packets_out)
1272  
1273  void tcp_enter_cwr(struct sock *sk);
1274  __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1275  
1276  /* The maximum number of MSS of available cwnd for which TSO defers
1277   * sending if not using sysctl_tcp_tso_win_divisor.
1278   */
tcp_max_tso_deferred_mss(const struct tcp_sock * tp)1279  static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1280  {
1281  	return 3;
1282  }
1283  
1284  /* Returns end sequence number of the receiver's advertised window */
tcp_wnd_end(const struct tcp_sock * tp)1285  static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1286  {
1287  	return tp->snd_una + tp->snd_wnd;
1288  }
1289  
1290  /* We follow the spirit of RFC2861 to validate cwnd but implement a more
1291   * flexible approach. The RFC suggests cwnd should not be raised unless
1292   * it was fully used previously. And that's exactly what we do in
1293   * congestion avoidance mode. But in slow start we allow cwnd to grow
1294   * as long as the application has used half the cwnd.
1295   * Example :
1296   *    cwnd is 10 (IW10), but application sends 9 frames.
1297   *    We allow cwnd to reach 18 when all frames are ACKed.
1298   * This check is safe because it's as aggressive as slow start which already
1299   * risks 100% overshoot. The advantage is that we discourage application to
1300   * either send more filler packets or data to artificially blow up the cwnd
1301   * usage, and allow application-limited process to probe bw more aggressively.
1302   */
tcp_is_cwnd_limited(const struct sock * sk)1303  static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1304  {
1305  	const struct tcp_sock *tp = tcp_sk(sk);
1306  
1307  	if (tp->is_cwnd_limited)
1308  		return true;
1309  
1310  	/* If in slow start, ensure cwnd grows to twice what was ACKed. */
1311  	if (tcp_in_slow_start(tp))
1312  		return tcp_snd_cwnd(tp) < 2 * tp->max_packets_out;
1313  
1314  	return false;
1315  }
1316  
1317  /* BBR congestion control needs pacing.
1318   * Same remark for SO_MAX_PACING_RATE.
1319   * sch_fq packet scheduler is efficiently handling pacing,
1320   * but is not always installed/used.
1321   * Return true if TCP stack should pace packets itself.
1322   */
tcp_needs_internal_pacing(const struct sock * sk)1323  static inline bool tcp_needs_internal_pacing(const struct sock *sk)
1324  {
1325  	return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED;
1326  }
1327  
1328  /* Estimates in how many jiffies next packet for this flow can be sent.
1329   * Scheduling a retransmit timer too early would be silly.
1330   */
tcp_pacing_delay(const struct sock * sk)1331  static inline unsigned long tcp_pacing_delay(const struct sock *sk)
1332  {
1333  	s64 delay = tcp_sk(sk)->tcp_wstamp_ns - tcp_sk(sk)->tcp_clock_cache;
1334  
1335  	return delay > 0 ? nsecs_to_jiffies(delay) : 0;
1336  }
1337  
tcp_reset_xmit_timer(struct sock * sk,const int what,unsigned long when,const unsigned long max_when)1338  static inline void tcp_reset_xmit_timer(struct sock *sk,
1339  					const int what,
1340  					unsigned long when,
1341  					const unsigned long max_when)
1342  {
1343  	inet_csk_reset_xmit_timer(sk, what, when + tcp_pacing_delay(sk),
1344  				  max_when);
1345  }
1346  
1347  /* Something is really bad, we could not queue an additional packet,
1348   * because qdisc is full or receiver sent a 0 window, or we are paced.
1349   * We do not want to add fuel to the fire, or abort too early,
1350   * so make sure the timer we arm now is at least 200ms in the future,
1351   * regardless of current icsk_rto value (as it could be ~2ms)
1352   */
tcp_probe0_base(const struct sock * sk)1353  static inline unsigned long tcp_probe0_base(const struct sock *sk)
1354  {
1355  	return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1356  }
1357  
1358  /* Variant of inet_csk_rto_backoff() used for zero window probes */
tcp_probe0_when(const struct sock * sk,unsigned long max_when)1359  static inline unsigned long tcp_probe0_when(const struct sock *sk,
1360  					    unsigned long max_when)
1361  {
1362  	u8 backoff = min_t(u8, ilog2(TCP_RTO_MAX / TCP_RTO_MIN) + 1,
1363  			   inet_csk(sk)->icsk_backoff);
1364  	u64 when = (u64)tcp_probe0_base(sk) << backoff;
1365  
1366  	return (unsigned long)min_t(u64, when, max_when);
1367  }
1368  
tcp_check_probe_timer(struct sock * sk)1369  static inline void tcp_check_probe_timer(struct sock *sk)
1370  {
1371  	if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1372  		tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1373  				     tcp_probe0_base(sk), TCP_RTO_MAX);
1374  }
1375  
tcp_init_wl(struct tcp_sock * tp,u32 seq)1376  static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1377  {
1378  	tp->snd_wl1 = seq;
1379  }
1380  
tcp_update_wl(struct tcp_sock * tp,u32 seq)1381  static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1382  {
1383  	tp->snd_wl1 = seq;
1384  }
1385  
1386  /*
1387   * Calculate(/check) TCP checksum
1388   */
tcp_v4_check(int len,__be32 saddr,__be32 daddr,__wsum base)1389  static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1390  				   __be32 daddr, __wsum base)
1391  {
1392  	return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_TCP, base);
1393  }
1394  
tcp_checksum_complete(struct sk_buff * skb)1395  static inline bool tcp_checksum_complete(struct sk_buff *skb)
1396  {
1397  	return !skb_csum_unnecessary(skb) &&
1398  		__skb_checksum_complete(skb);
1399  }
1400  
1401  bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb,
1402  		     enum skb_drop_reason *reason);
1403  
1404  
1405  int tcp_filter(struct sock *sk, struct sk_buff *skb);
1406  void tcp_set_state(struct sock *sk, int state);
1407  void tcp_done(struct sock *sk);
1408  int tcp_abort(struct sock *sk, int err);
1409  
tcp_sack_reset(struct tcp_options_received * rx_opt)1410  static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1411  {
1412  	rx_opt->dsack = 0;
1413  	rx_opt->num_sacks = 0;
1414  }
1415  
1416  void tcp_cwnd_restart(struct sock *sk, s32 delta);
1417  
tcp_slow_start_after_idle_check(struct sock * sk)1418  static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1419  {
1420  	const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
1421  	struct tcp_sock *tp = tcp_sk(sk);
1422  	s32 delta;
1423  
1424  	if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle) ||
1425  	    tp->packets_out || ca_ops->cong_control)
1426  		return;
1427  	delta = tcp_jiffies32 - tp->lsndtime;
1428  	if (delta > inet_csk(sk)->icsk_rto)
1429  		tcp_cwnd_restart(sk, delta);
1430  }
1431  
1432  /* Determine a window scaling and initial window to offer. */
1433  void tcp_select_initial_window(const struct sock *sk, int __space,
1434  			       __u32 mss, __u32 *rcv_wnd,
1435  			       __u32 *window_clamp, int wscale_ok,
1436  			       __u8 *rcv_wscale, __u32 init_rcv_wnd);
1437  
__tcp_win_from_space(u8 scaling_ratio,int space)1438  static inline int __tcp_win_from_space(u8 scaling_ratio, int space)
1439  {
1440  	s64 scaled_space = (s64)space * scaling_ratio;
1441  
1442  	return scaled_space >> TCP_RMEM_TO_WIN_SCALE;
1443  }
1444  
tcp_win_from_space(const struct sock * sk,int space)1445  static inline int tcp_win_from_space(const struct sock *sk, int space)
1446  {
1447  	return __tcp_win_from_space(tcp_sk(sk)->scaling_ratio, space);
1448  }
1449  
1450  /* inverse of __tcp_win_from_space() */
__tcp_space_from_win(u8 scaling_ratio,int win)1451  static inline int __tcp_space_from_win(u8 scaling_ratio, int win)
1452  {
1453  	u64 val = (u64)win << TCP_RMEM_TO_WIN_SCALE;
1454  
1455  	do_div(val, scaling_ratio);
1456  	return val;
1457  }
1458  
tcp_space_from_win(const struct sock * sk,int win)1459  static inline int tcp_space_from_win(const struct sock *sk, int win)
1460  {
1461  	return __tcp_space_from_win(tcp_sk(sk)->scaling_ratio, win);
1462  }
1463  
1464  /* Assume a 50% default for skb->len/skb->truesize ratio.
1465   * This may be adjusted later in tcp_measure_rcv_mss().
1466   */
1467  #define TCP_DEFAULT_SCALING_RATIO (1 << (TCP_RMEM_TO_WIN_SCALE - 1))
1468  
tcp_scaling_ratio_init(struct sock * sk)1469  static inline void tcp_scaling_ratio_init(struct sock *sk)
1470  {
1471  	tcp_sk(sk)->scaling_ratio = TCP_DEFAULT_SCALING_RATIO;
1472  }
1473  
1474  /* Note: caller must be prepared to deal with negative returns */
tcp_space(const struct sock * sk)1475  static inline int tcp_space(const struct sock *sk)
1476  {
1477  	return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf) -
1478  				  READ_ONCE(sk->sk_backlog.len) -
1479  				  atomic_read(&sk->sk_rmem_alloc));
1480  }
1481  
tcp_full_space(const struct sock * sk)1482  static inline int tcp_full_space(const struct sock *sk)
1483  {
1484  	return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
1485  }
1486  
__tcp_adjust_rcv_ssthresh(struct sock * sk,u32 new_ssthresh)1487  static inline void __tcp_adjust_rcv_ssthresh(struct sock *sk, u32 new_ssthresh)
1488  {
1489  	int unused_mem = sk_unused_reserved_mem(sk);
1490  	struct tcp_sock *tp = tcp_sk(sk);
1491  
1492  	tp->rcv_ssthresh = min(tp->rcv_ssthresh, new_ssthresh);
1493  	if (unused_mem)
1494  		tp->rcv_ssthresh = max_t(u32, tp->rcv_ssthresh,
1495  					 tcp_win_from_space(sk, unused_mem));
1496  }
1497  
tcp_adjust_rcv_ssthresh(struct sock * sk)1498  static inline void tcp_adjust_rcv_ssthresh(struct sock *sk)
1499  {
1500  	__tcp_adjust_rcv_ssthresh(sk, 4U * tcp_sk(sk)->advmss);
1501  }
1502  
1503  void tcp_cleanup_rbuf(struct sock *sk, int copied);
1504  void __tcp_cleanup_rbuf(struct sock *sk, int copied);
1505  
1506  
1507  /* We provision sk_rcvbuf around 200% of sk_rcvlowat.
1508   * If 87.5 % (7/8) of the space has been consumed, we want to override
1509   * SO_RCVLOWAT constraint, since we are receiving skbs with too small
1510   * len/truesize ratio.
1511   */
tcp_rmem_pressure(const struct sock * sk)1512  static inline bool tcp_rmem_pressure(const struct sock *sk)
1513  {
1514  	int rcvbuf, threshold;
1515  
1516  	if (tcp_under_memory_pressure(sk))
1517  		return true;
1518  
1519  	rcvbuf = READ_ONCE(sk->sk_rcvbuf);
1520  	threshold = rcvbuf - (rcvbuf >> 3);
1521  
1522  	return atomic_read(&sk->sk_rmem_alloc) > threshold;
1523  }
1524  
tcp_epollin_ready(const struct sock * sk,int target)1525  static inline bool tcp_epollin_ready(const struct sock *sk, int target)
1526  {
1527  	const struct tcp_sock *tp = tcp_sk(sk);
1528  	int avail = READ_ONCE(tp->rcv_nxt) - READ_ONCE(tp->copied_seq);
1529  
1530  	if (avail <= 0)
1531  		return false;
1532  
1533  	return (avail >= target) || tcp_rmem_pressure(sk) ||
1534  	       (tcp_receive_window(tp) <= inet_csk(sk)->icsk_ack.rcv_mss);
1535  }
1536  
1537  extern void tcp_openreq_init_rwin(struct request_sock *req,
1538  				  const struct sock *sk_listener,
1539  				  const struct dst_entry *dst);
1540  
1541  void tcp_enter_memory_pressure(struct sock *sk);
1542  void tcp_leave_memory_pressure(struct sock *sk);
1543  
keepalive_intvl_when(const struct tcp_sock * tp)1544  static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1545  {
1546  	struct net *net = sock_net((struct sock *)tp);
1547  	int val;
1548  
1549  	/* Paired with WRITE_ONCE() in tcp_sock_set_keepintvl()
1550  	 * and do_tcp_setsockopt().
1551  	 */
1552  	val = READ_ONCE(tp->keepalive_intvl);
1553  
1554  	return val ? : READ_ONCE(net->ipv4.sysctl_tcp_keepalive_intvl);
1555  }
1556  
keepalive_time_when(const struct tcp_sock * tp)1557  static inline int keepalive_time_when(const struct tcp_sock *tp)
1558  {
1559  	struct net *net = sock_net((struct sock *)tp);
1560  	int val;
1561  
1562  	/* Paired with WRITE_ONCE() in tcp_sock_set_keepidle_locked() */
1563  	val = READ_ONCE(tp->keepalive_time);
1564  
1565  	return val ? : READ_ONCE(net->ipv4.sysctl_tcp_keepalive_time);
1566  }
1567  
keepalive_probes(const struct tcp_sock * tp)1568  static inline int keepalive_probes(const struct tcp_sock *tp)
1569  {
1570  	struct net *net = sock_net((struct sock *)tp);
1571  	int val;
1572  
1573  	/* Paired with WRITE_ONCE() in tcp_sock_set_keepcnt()
1574  	 * and do_tcp_setsockopt().
1575  	 */
1576  	val = READ_ONCE(tp->keepalive_probes);
1577  
1578  	return val ? : READ_ONCE(net->ipv4.sysctl_tcp_keepalive_probes);
1579  }
1580  
keepalive_time_elapsed(const struct tcp_sock * tp)1581  static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1582  {
1583  	const struct inet_connection_sock *icsk = &tp->inet_conn;
1584  
1585  	return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime,
1586  			  tcp_jiffies32 - tp->rcv_tstamp);
1587  }
1588  
tcp_fin_time(const struct sock * sk)1589  static inline int tcp_fin_time(const struct sock *sk)
1590  {
1591  	int fin_timeout = tcp_sk(sk)->linger2 ? :
1592  		READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fin_timeout);
1593  	const int rto = inet_csk(sk)->icsk_rto;
1594  
1595  	if (fin_timeout < (rto << 2) - (rto >> 1))
1596  		fin_timeout = (rto << 2) - (rto >> 1);
1597  
1598  	return fin_timeout;
1599  }
1600  
tcp_paws_check(const struct tcp_options_received * rx_opt,int paws_win)1601  static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1602  				  int paws_win)
1603  {
1604  	if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1605  		return true;
1606  	if (unlikely(!time_before32(ktime_get_seconds(),
1607  				    rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)))
1608  		return true;
1609  	/*
1610  	 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1611  	 * then following tcp messages have valid values. Ignore 0 value,
1612  	 * or else 'negative' tsval might forbid us to accept their packets.
1613  	 */
1614  	if (!rx_opt->ts_recent)
1615  		return true;
1616  	return false;
1617  }
1618  
tcp_paws_reject(const struct tcp_options_received * rx_opt,int rst)1619  static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1620  				   int rst)
1621  {
1622  	if (tcp_paws_check(rx_opt, 0))
1623  		return false;
1624  
1625  	/* RST segments are not recommended to carry timestamp,
1626  	   and, if they do, it is recommended to ignore PAWS because
1627  	   "their cleanup function should take precedence over timestamps."
1628  	   Certainly, it is mistake. It is necessary to understand the reasons
1629  	   of this constraint to relax it: if peer reboots, clock may go
1630  	   out-of-sync and half-open connections will not be reset.
1631  	   Actually, the problem would be not existing if all
1632  	   the implementations followed draft about maintaining clock
1633  	   via reboots. Linux-2.2 DOES NOT!
1634  
1635  	   However, we can relax time bounds for RST segments to MSL.
1636  	 */
1637  	if (rst && !time_before32(ktime_get_seconds(),
1638  				  rx_opt->ts_recent_stamp + TCP_PAWS_MSL))
1639  		return false;
1640  	return true;
1641  }
1642  
1643  bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1644  			  int mib_idx, u32 *last_oow_ack_time);
1645  
tcp_mib_init(struct net * net)1646  static inline void tcp_mib_init(struct net *net)
1647  {
1648  	/* See RFC 2012 */
1649  	TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
1650  	TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1651  	TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1652  	TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
1653  }
1654  
1655  /* from STCP */
tcp_clear_retrans_hints_partial(struct tcp_sock * tp)1656  static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1657  {
1658  	tp->lost_skb_hint = NULL;
1659  }
1660  
tcp_clear_all_retrans_hints(struct tcp_sock * tp)1661  static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1662  {
1663  	tcp_clear_retrans_hints_partial(tp);
1664  	tp->retransmit_skb_hint = NULL;
1665  }
1666  
1667  union tcp_md5_addr {
1668  	struct in_addr  a4;
1669  #if IS_ENABLED(CONFIG_IPV6)
1670  	struct in6_addr	a6;
1671  #endif
1672  };
1673  
1674  /* - key database */
1675  struct tcp_md5sig_key {
1676  	struct hlist_node	node;
1677  	u8			keylen;
1678  	u8			family; /* AF_INET or AF_INET6 */
1679  	u8			prefixlen;
1680  	u8			flags;
1681  	union tcp_md5_addr	addr;
1682  	int			l3index; /* set if key added with L3 scope */
1683  	u8			key[TCP_MD5SIG_MAXKEYLEN];
1684  	struct rcu_head		rcu;
1685  };
1686  
1687  /* - sock block */
1688  struct tcp_md5sig_info {
1689  	struct hlist_head	head;
1690  	struct rcu_head		rcu;
1691  };
1692  
1693  /* - pseudo header */
1694  struct tcp4_pseudohdr {
1695  	__be32		saddr;
1696  	__be32		daddr;
1697  	__u8		pad;
1698  	__u8		protocol;
1699  	__be16		len;
1700  };
1701  
1702  struct tcp6_pseudohdr {
1703  	struct in6_addr	saddr;
1704  	struct in6_addr daddr;
1705  	__be32		len;
1706  	__be32		protocol;	/* including padding */
1707  };
1708  
1709  union tcp_md5sum_block {
1710  	struct tcp4_pseudohdr ip4;
1711  #if IS_ENABLED(CONFIG_IPV6)
1712  	struct tcp6_pseudohdr ip6;
1713  #endif
1714  };
1715  
1716  /* - pool: digest algorithm, hash description and scratch buffer */
1717  struct tcp_md5sig_pool {
1718  	struct ahash_request	*md5_req;
1719  	void			*scratch;
1720  };
1721  
1722  /* - functions */
1723  int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1724  			const struct sock *sk, const struct sk_buff *skb);
1725  int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1726  		   int family, u8 prefixlen, int l3index, u8 flags,
1727  		   const u8 *newkey, u8 newkeylen);
1728  int tcp_md5_key_copy(struct sock *sk, const union tcp_md5_addr *addr,
1729  		     int family, u8 prefixlen, int l3index,
1730  		     struct tcp_md5sig_key *key);
1731  
1732  int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1733  		   int family, u8 prefixlen, int l3index, u8 flags);
1734  struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1735  					 const struct sock *addr_sk);
1736  
1737  #ifdef CONFIG_TCP_MD5SIG
1738  #include <linux/jump_label.h>
1739  extern struct static_key_false_deferred tcp_md5_needed;
1740  struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, int l3index,
1741  					   const union tcp_md5_addr *addr,
1742  					   int family);
1743  static inline struct tcp_md5sig_key *
tcp_md5_do_lookup(const struct sock * sk,int l3index,const union tcp_md5_addr * addr,int family)1744  tcp_md5_do_lookup(const struct sock *sk, int l3index,
1745  		  const union tcp_md5_addr *addr, int family)
1746  {
1747  	if (!static_branch_unlikely(&tcp_md5_needed.key))
1748  		return NULL;
1749  	return __tcp_md5_do_lookup(sk, l3index, addr, family);
1750  }
1751  
1752  enum skb_drop_reason
1753  tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
1754  		     const void *saddr, const void *daddr,
1755  		     int family, int dif, int sdif);
1756  
1757  
1758  #define tcp_twsk_md5_key(twsk)	((twsk)->tw_md5_key)
1759  #else
1760  static inline struct tcp_md5sig_key *
tcp_md5_do_lookup(const struct sock * sk,int l3index,const union tcp_md5_addr * addr,int family)1761  tcp_md5_do_lookup(const struct sock *sk, int l3index,
1762  		  const union tcp_md5_addr *addr, int family)
1763  {
1764  	return NULL;
1765  }
1766  
1767  static inline enum skb_drop_reason
tcp_inbound_md5_hash(const struct sock * sk,const struct sk_buff * skb,const void * saddr,const void * daddr,int family,int dif,int sdif)1768  tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
1769  		     const void *saddr, const void *daddr,
1770  		     int family, int dif, int sdif)
1771  {
1772  	return SKB_NOT_DROPPED_YET;
1773  }
1774  #define tcp_twsk_md5_key(twsk)	NULL
1775  #endif
1776  
1777  bool tcp_alloc_md5sig_pool(void);
1778  
1779  struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
tcp_put_md5sig_pool(void)1780  static inline void tcp_put_md5sig_pool(void)
1781  {
1782  	local_bh_enable();
1783  }
1784  
1785  int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1786  			  unsigned int header_len);
1787  int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1788  		     const struct tcp_md5sig_key *key);
1789  
1790  /* From tcp_fastopen.c */
1791  void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1792  			    struct tcp_fastopen_cookie *cookie);
1793  void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1794  			    struct tcp_fastopen_cookie *cookie, bool syn_lost,
1795  			    u16 try_exp);
1796  struct tcp_fastopen_request {
1797  	/* Fast Open cookie. Size 0 means a cookie request */
1798  	struct tcp_fastopen_cookie	cookie;
1799  	struct msghdr			*data;  /* data in MSG_FASTOPEN */
1800  	size_t				size;
1801  	int				copied;	/* queued in tcp_connect() */
1802  	struct ubuf_info		*uarg;
1803  };
1804  void tcp_free_fastopen_req(struct tcp_sock *tp);
1805  void tcp_fastopen_destroy_cipher(struct sock *sk);
1806  void tcp_fastopen_ctx_destroy(struct net *net);
1807  int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
1808  			      void *primary_key, void *backup_key);
1809  int tcp_fastopen_get_cipher(struct net *net, struct inet_connection_sock *icsk,
1810  			    u64 *key);
1811  void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1812  struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1813  			      struct request_sock *req,
1814  			      struct tcp_fastopen_cookie *foc,
1815  			      const struct dst_entry *dst);
1816  void tcp_fastopen_init_key_once(struct net *net);
1817  bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
1818  			     struct tcp_fastopen_cookie *cookie);
1819  bool tcp_fastopen_defer_connect(struct sock *sk, int *err);
1820  #define TCP_FASTOPEN_KEY_LENGTH sizeof(siphash_key_t)
1821  #define TCP_FASTOPEN_KEY_MAX 2
1822  #define TCP_FASTOPEN_KEY_BUF_LENGTH \
1823  	(TCP_FASTOPEN_KEY_LENGTH * TCP_FASTOPEN_KEY_MAX)
1824  
1825  /* Fastopen key context */
1826  struct tcp_fastopen_context {
1827  	siphash_key_t	key[TCP_FASTOPEN_KEY_MAX];
1828  	int		num;
1829  	struct rcu_head	rcu;
1830  };
1831  
1832  void tcp_fastopen_active_disable(struct sock *sk);
1833  bool tcp_fastopen_active_should_disable(struct sock *sk);
1834  void tcp_fastopen_active_disable_ofo_check(struct sock *sk);
1835  void tcp_fastopen_active_detect_blackhole(struct sock *sk, bool expired);
1836  
1837  /* Caller needs to wrap with rcu_read_(un)lock() */
1838  static inline
tcp_fastopen_get_ctx(const struct sock * sk)1839  struct tcp_fastopen_context *tcp_fastopen_get_ctx(const struct sock *sk)
1840  {
1841  	struct tcp_fastopen_context *ctx;
1842  
1843  	ctx = rcu_dereference(inet_csk(sk)->icsk_accept_queue.fastopenq.ctx);
1844  	if (!ctx)
1845  		ctx = rcu_dereference(sock_net(sk)->ipv4.tcp_fastopen_ctx);
1846  	return ctx;
1847  }
1848  
1849  static inline
tcp_fastopen_cookie_match(const struct tcp_fastopen_cookie * foc,const struct tcp_fastopen_cookie * orig)1850  bool tcp_fastopen_cookie_match(const struct tcp_fastopen_cookie *foc,
1851  			       const struct tcp_fastopen_cookie *orig)
1852  {
1853  	if (orig->len == TCP_FASTOPEN_COOKIE_SIZE &&
1854  	    orig->len == foc->len &&
1855  	    !memcmp(orig->val, foc->val, foc->len))
1856  		return true;
1857  	return false;
1858  }
1859  
1860  static inline
tcp_fastopen_context_len(const struct tcp_fastopen_context * ctx)1861  int tcp_fastopen_context_len(const struct tcp_fastopen_context *ctx)
1862  {
1863  	return ctx->num;
1864  }
1865  
1866  /* Latencies incurred by various limits for a sender. They are
1867   * chronograph-like stats that are mutually exclusive.
1868   */
1869  enum tcp_chrono {
1870  	TCP_CHRONO_UNSPEC,
1871  	TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
1872  	TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
1873  	TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
1874  	__TCP_CHRONO_MAX,
1875  };
1876  
1877  void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
1878  void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);
1879  
1880  /* This helper is needed, because skb->tcp_tsorted_anchor uses
1881   * the same memory storage than skb->destructor/_skb_refdst
1882   */
tcp_skb_tsorted_anchor_cleanup(struct sk_buff * skb)1883  static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb)
1884  {
1885  	skb->destructor = NULL;
1886  	skb->_skb_refdst = 0UL;
1887  }
1888  
1889  #define tcp_skb_tsorted_save(skb) {		\
1890  	unsigned long _save = skb->_skb_refdst;	\
1891  	skb->_skb_refdst = 0UL;
1892  
1893  #define tcp_skb_tsorted_restore(skb)		\
1894  	skb->_skb_refdst = _save;		\
1895  }
1896  
1897  void tcp_write_queue_purge(struct sock *sk);
1898  
tcp_rtx_queue_head(const struct sock * sk)1899  static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk)
1900  {
1901  	return skb_rb_first(&sk->tcp_rtx_queue);
1902  }
1903  
tcp_rtx_queue_tail(const struct sock * sk)1904  static inline struct sk_buff *tcp_rtx_queue_tail(const struct sock *sk)
1905  {
1906  	return skb_rb_last(&sk->tcp_rtx_queue);
1907  }
1908  
tcp_write_queue_tail(const struct sock * sk)1909  static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1910  {
1911  	return skb_peek_tail(&sk->sk_write_queue);
1912  }
1913  
1914  #define tcp_for_write_queue_from_safe(skb, tmp, sk)			\
1915  	skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1916  
tcp_send_head(const struct sock * sk)1917  static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1918  {
1919  	return skb_peek(&sk->sk_write_queue);
1920  }
1921  
tcp_skb_is_last(const struct sock * sk,const struct sk_buff * skb)1922  static inline bool tcp_skb_is_last(const struct sock *sk,
1923  				   const struct sk_buff *skb)
1924  {
1925  	return skb_queue_is_last(&sk->sk_write_queue, skb);
1926  }
1927  
1928  /**
1929   * tcp_write_queue_empty - test if any payload (or FIN) is available in write queue
1930   * @sk: socket
1931   *
1932   * Since the write queue can have a temporary empty skb in it,
1933   * we must not use "return skb_queue_empty(&sk->sk_write_queue)"
1934   */
tcp_write_queue_empty(const struct sock * sk)1935  static inline bool tcp_write_queue_empty(const struct sock *sk)
1936  {
1937  	const struct tcp_sock *tp = tcp_sk(sk);
1938  
1939  	return tp->write_seq == tp->snd_nxt;
1940  }
1941  
tcp_rtx_queue_empty(const struct sock * sk)1942  static inline bool tcp_rtx_queue_empty(const struct sock *sk)
1943  {
1944  	return RB_EMPTY_ROOT(&sk->tcp_rtx_queue);
1945  }
1946  
tcp_rtx_and_write_queues_empty(const struct sock * sk)1947  static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk)
1948  {
1949  	return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk);
1950  }
1951  
tcp_add_write_queue_tail(struct sock * sk,struct sk_buff * skb)1952  static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1953  {
1954  	__skb_queue_tail(&sk->sk_write_queue, skb);
1955  
1956  	/* Queue it, remembering where we must start sending. */
1957  	if (sk->sk_write_queue.next == skb)
1958  		tcp_chrono_start(sk, TCP_CHRONO_BUSY);
1959  }
1960  
1961  /* Insert new before skb on the write queue of sk.  */
tcp_insert_write_queue_before(struct sk_buff * new,struct sk_buff * skb,struct sock * sk)1962  static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1963  						  struct sk_buff *skb,
1964  						  struct sock *sk)
1965  {
1966  	__skb_queue_before(&sk->sk_write_queue, skb, new);
1967  }
1968  
tcp_unlink_write_queue(struct sk_buff * skb,struct sock * sk)1969  static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1970  {
1971  	tcp_skb_tsorted_anchor_cleanup(skb);
1972  	__skb_unlink(skb, &sk->sk_write_queue);
1973  }
1974  
1975  void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb);
1976  
tcp_rtx_queue_unlink(struct sk_buff * skb,struct sock * sk)1977  static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk)
1978  {
1979  	tcp_skb_tsorted_anchor_cleanup(skb);
1980  	rb_erase(&skb->rbnode, &sk->tcp_rtx_queue);
1981  }
1982  
tcp_rtx_queue_unlink_and_free(struct sk_buff * skb,struct sock * sk)1983  static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk)
1984  {
1985  	list_del(&skb->tcp_tsorted_anchor);
1986  	tcp_rtx_queue_unlink(skb, sk);
1987  	tcp_wmem_free_skb(sk, skb);
1988  }
1989  
tcp_push_pending_frames(struct sock * sk)1990  static inline void tcp_push_pending_frames(struct sock *sk)
1991  {
1992  	if (tcp_send_head(sk)) {
1993  		struct tcp_sock *tp = tcp_sk(sk);
1994  
1995  		__tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1996  	}
1997  }
1998  
1999  /* Start sequence of the skb just after the highest skb with SACKed
2000   * bit, valid only if sacked_out > 0 or when the caller has ensured
2001   * validity by itself.
2002   */
tcp_highest_sack_seq(struct tcp_sock * tp)2003  static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
2004  {
2005  	if (!tp->sacked_out)
2006  		return tp->snd_una;
2007  
2008  	if (tp->highest_sack == NULL)
2009  		return tp->snd_nxt;
2010  
2011  	return TCP_SKB_CB(tp->highest_sack)->seq;
2012  }
2013  
tcp_advance_highest_sack(struct sock * sk,struct sk_buff * skb)2014  static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
2015  {
2016  	tcp_sk(sk)->highest_sack = skb_rb_next(skb);
2017  }
2018  
tcp_highest_sack(struct sock * sk)2019  static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
2020  {
2021  	return tcp_sk(sk)->highest_sack;
2022  }
2023  
tcp_highest_sack_reset(struct sock * sk)2024  static inline void tcp_highest_sack_reset(struct sock *sk)
2025  {
2026  	tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk);
2027  }
2028  
2029  /* Called when old skb is about to be deleted and replaced by new skb */
tcp_highest_sack_replace(struct sock * sk,struct sk_buff * old,struct sk_buff * new)2030  static inline void tcp_highest_sack_replace(struct sock *sk,
2031  					    struct sk_buff *old,
2032  					    struct sk_buff *new)
2033  {
2034  	if (old == tcp_highest_sack(sk))
2035  		tcp_sk(sk)->highest_sack = new;
2036  }
2037  
2038  /* This helper checks if socket has IP_TRANSPARENT set */
inet_sk_transparent(const struct sock * sk)2039  static inline bool inet_sk_transparent(const struct sock *sk)
2040  {
2041  	switch (sk->sk_state) {
2042  	case TCP_TIME_WAIT:
2043  		return inet_twsk(sk)->tw_transparent;
2044  	case TCP_NEW_SYN_RECV:
2045  		return inet_rsk(inet_reqsk(sk))->no_srccheck;
2046  	}
2047  	return inet_test_bit(TRANSPARENT, sk);
2048  }
2049  
2050  /* Determines whether this is a thin stream (which may suffer from
2051   * increased latency). Used to trigger latency-reducing mechanisms.
2052   */
tcp_stream_is_thin(struct tcp_sock * tp)2053  static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
2054  {
2055  	return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
2056  }
2057  
2058  /* /proc */
2059  enum tcp_seq_states {
2060  	TCP_SEQ_STATE_LISTENING,
2061  	TCP_SEQ_STATE_ESTABLISHED,
2062  };
2063  
2064  void *tcp_seq_start(struct seq_file *seq, loff_t *pos);
2065  void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos);
2066  void tcp_seq_stop(struct seq_file *seq, void *v);
2067  
2068  struct tcp_seq_afinfo {
2069  	sa_family_t			family;
2070  };
2071  
2072  struct tcp_iter_state {
2073  	struct seq_net_private	p;
2074  	enum tcp_seq_states	state;
2075  	struct sock		*syn_wait_sk;
2076  	int			bucket, offset, sbucket, num;
2077  	loff_t			last_pos;
2078  };
2079  
2080  extern struct request_sock_ops tcp_request_sock_ops;
2081  extern struct request_sock_ops tcp6_request_sock_ops;
2082  
2083  void tcp_v4_destroy_sock(struct sock *sk);
2084  
2085  struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
2086  				netdev_features_t features);
2087  struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb);
2088  INDIRECT_CALLABLE_DECLARE(int tcp4_gro_complete(struct sk_buff *skb, int thoff));
2089  INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb));
2090  INDIRECT_CALLABLE_DECLARE(int tcp6_gro_complete(struct sk_buff *skb, int thoff));
2091  INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp6_gro_receive(struct list_head *head, struct sk_buff *skb));
2092  void tcp_gro_complete(struct sk_buff *skb);
2093  
2094  void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
2095  
tcp_notsent_lowat(const struct tcp_sock * tp)2096  static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
2097  {
2098  	struct net *net = sock_net((struct sock *)tp);
2099  	u32 val;
2100  
2101  	val = READ_ONCE(tp->notsent_lowat);
2102  
2103  	return val ?: READ_ONCE(net->ipv4.sysctl_tcp_notsent_lowat);
2104  }
2105  
2106  bool tcp_stream_memory_free(const struct sock *sk, int wake);
2107  
2108  #ifdef CONFIG_PROC_FS
2109  int tcp4_proc_init(void);
2110  void tcp4_proc_exit(void);
2111  #endif
2112  
2113  int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
2114  int tcp_conn_request(struct request_sock_ops *rsk_ops,
2115  		     const struct tcp_request_sock_ops *af_ops,
2116  		     struct sock *sk, struct sk_buff *skb);
2117  
2118  /* TCP af-specific functions */
2119  struct tcp_sock_af_ops {
2120  #ifdef CONFIG_TCP_MD5SIG
2121  	struct tcp_md5sig_key	*(*md5_lookup) (const struct sock *sk,
2122  						const struct sock *addr_sk);
2123  	int		(*calc_md5_hash)(char *location,
2124  					 const struct tcp_md5sig_key *md5,
2125  					 const struct sock *sk,
2126  					 const struct sk_buff *skb);
2127  	int		(*md5_parse)(struct sock *sk,
2128  				     int optname,
2129  				     sockptr_t optval,
2130  				     int optlen);
2131  #endif
2132  };
2133  
2134  struct tcp_request_sock_ops {
2135  	u16 mss_clamp;
2136  #ifdef CONFIG_TCP_MD5SIG
2137  	struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
2138  						 const struct sock *addr_sk);
2139  	int		(*calc_md5_hash) (char *location,
2140  					  const struct tcp_md5sig_key *md5,
2141  					  const struct sock *sk,
2142  					  const struct sk_buff *skb);
2143  #endif
2144  #ifdef CONFIG_SYN_COOKIES
2145  	__u32 (*cookie_init_seq)(const struct sk_buff *skb,
2146  				 __u16 *mss);
2147  #endif
2148  	struct dst_entry *(*route_req)(const struct sock *sk,
2149  				       struct sk_buff *skb,
2150  				       struct flowi *fl,
2151  				       struct request_sock *req);
2152  	u32 (*init_seq)(const struct sk_buff *skb);
2153  	u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb);
2154  	int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
2155  			   struct flowi *fl, struct request_sock *req,
2156  			   struct tcp_fastopen_cookie *foc,
2157  			   enum tcp_synack_type synack_type,
2158  			   struct sk_buff *syn_skb);
2159  };
2160  
2161  extern const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops;
2162  #if IS_ENABLED(CONFIG_IPV6)
2163  extern const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops;
2164  #endif
2165  
2166  #ifdef CONFIG_SYN_COOKIES
cookie_init_sequence(const struct tcp_request_sock_ops * ops,const struct sock * sk,struct sk_buff * skb,__u16 * mss)2167  static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
2168  					 const struct sock *sk, struct sk_buff *skb,
2169  					 __u16 *mss)
2170  {
2171  	tcp_synq_overflow(sk);
2172  	__NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
2173  	return ops->cookie_init_seq(skb, mss);
2174  }
2175  #else
cookie_init_sequence(const struct tcp_request_sock_ops * ops,const struct sock * sk,struct sk_buff * skb,__u16 * mss)2176  static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
2177  					 const struct sock *sk, struct sk_buff *skb,
2178  					 __u16 *mss)
2179  {
2180  	return 0;
2181  }
2182  #endif
2183  
2184  int tcpv4_offload_init(void);
2185  
2186  void tcp_v4_init(void);
2187  void tcp_init(void);
2188  
2189  /* tcp_recovery.c */
2190  void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb);
2191  void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced);
2192  extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb,
2193  				u32 reo_wnd);
2194  extern bool tcp_rack_mark_lost(struct sock *sk);
2195  extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
2196  			     u64 xmit_time);
2197  extern void tcp_rack_reo_timeout(struct sock *sk);
2198  extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs);
2199  
2200  /* tcp_plb.c */
2201  
2202  /*
2203   * Scaling factor for fractions in PLB. For example, tcp_plb_update_state
2204   * expects cong_ratio which represents fraction of traffic that experienced
2205   * congestion over a single RTT. In order to avoid floating point operations,
2206   * this fraction should be mapped to (1 << TCP_PLB_SCALE) and passed in.
2207   */
2208  #define TCP_PLB_SCALE 8
2209  
2210  /* State for PLB (Protective Load Balancing) for a single TCP connection. */
2211  struct tcp_plb_state {
2212  	u8	consec_cong_rounds:5, /* consecutive congested rounds */
2213  		unused:3;
2214  	u32	pause_until; /* jiffies32 when PLB can resume rerouting */
2215  };
2216  
tcp_plb_init(const struct sock * sk,struct tcp_plb_state * plb)2217  static inline void tcp_plb_init(const struct sock *sk,
2218  				struct tcp_plb_state *plb)
2219  {
2220  	plb->consec_cong_rounds = 0;
2221  	plb->pause_until = 0;
2222  }
2223  void tcp_plb_update_state(const struct sock *sk, struct tcp_plb_state *plb,
2224  			  const int cong_ratio);
2225  void tcp_plb_check_rehash(struct sock *sk, struct tcp_plb_state *plb);
2226  void tcp_plb_update_state_upon_rto(struct sock *sk, struct tcp_plb_state *plb);
2227  
2228  /* At how many usecs into the future should the RTO fire? */
tcp_rto_delta_us(const struct sock * sk)2229  static inline s64 tcp_rto_delta_us(const struct sock *sk)
2230  {
2231  	const struct sk_buff *skb = tcp_rtx_queue_head(sk);
2232  	u32 rto = inet_csk(sk)->icsk_rto;
2233  
2234  	if (likely(skb)) {
2235  		u64 rto_time_stamp_us = tcp_skb_timestamp_us(skb) + jiffies_to_usecs(rto);
2236  
2237  		return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp;
2238  	} else {
2239  		WARN_ONCE(1,
2240  			"rtx queue emtpy: "
2241  			"out:%u sacked:%u lost:%u retrans:%u "
2242  			"tlp_high_seq:%u sk_state:%u ca_state:%u "
2243  			"advmss:%u mss_cache:%u pmtu:%u\n",
2244  			tcp_sk(sk)->packets_out, tcp_sk(sk)->sacked_out,
2245  			tcp_sk(sk)->lost_out, tcp_sk(sk)->retrans_out,
2246  			tcp_sk(sk)->tlp_high_seq, sk->sk_state,
2247  			inet_csk(sk)->icsk_ca_state,
2248  			tcp_sk(sk)->advmss, tcp_sk(sk)->mss_cache,
2249  			inet_csk(sk)->icsk_pmtu_cookie);
2250  		return jiffies_to_usecs(rto);
2251  	}
2252  
2253  }
2254  
2255  /*
2256   * Save and compile IPv4 options, return a pointer to it
2257   */
tcp_v4_save_options(struct net * net,struct sk_buff * skb)2258  static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net,
2259  							 struct sk_buff *skb)
2260  {
2261  	const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
2262  	struct ip_options_rcu *dopt = NULL;
2263  
2264  	if (opt->optlen) {
2265  		int opt_size = sizeof(*dopt) + opt->optlen;
2266  
2267  		dopt = kmalloc(opt_size, GFP_ATOMIC);
2268  		if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) {
2269  			kfree(dopt);
2270  			dopt = NULL;
2271  		}
2272  	}
2273  	return dopt;
2274  }
2275  
2276  /* locally generated TCP pure ACKs have skb->truesize == 2
2277   * (check tcp_send_ack() in net/ipv4/tcp_output.c )
2278   * This is much faster than dissecting the packet to find out.
2279   * (Think of GRE encapsulations, IPv4, IPv6, ...)
2280   */
skb_is_tcp_pure_ack(const struct sk_buff * skb)2281  static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
2282  {
2283  	return skb->truesize == 2;
2284  }
2285  
skb_set_tcp_pure_ack(struct sk_buff * skb)2286  static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
2287  {
2288  	skb->truesize = 2;
2289  }
2290  
tcp_inq(struct sock * sk)2291  static inline int tcp_inq(struct sock *sk)
2292  {
2293  	struct tcp_sock *tp = tcp_sk(sk);
2294  	int answ;
2295  
2296  	if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
2297  		answ = 0;
2298  	} else if (sock_flag(sk, SOCK_URGINLINE) ||
2299  		   !tp->urg_data ||
2300  		   before(tp->urg_seq, tp->copied_seq) ||
2301  		   !before(tp->urg_seq, tp->rcv_nxt)) {
2302  
2303  		answ = tp->rcv_nxt - tp->copied_seq;
2304  
2305  		/* Subtract 1, if FIN was received */
2306  		if (answ && sock_flag(sk, SOCK_DONE))
2307  			answ--;
2308  	} else {
2309  		answ = tp->urg_seq - tp->copied_seq;
2310  	}
2311  
2312  	return answ;
2313  }
2314  
2315  int tcp_peek_len(struct socket *sock);
2316  
tcp_segs_in(struct tcp_sock * tp,const struct sk_buff * skb)2317  static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
2318  {
2319  	u16 segs_in;
2320  
2321  	segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
2322  
2323  	/* We update these fields while other threads might
2324  	 * read them from tcp_get_info()
2325  	 */
2326  	WRITE_ONCE(tp->segs_in, tp->segs_in + segs_in);
2327  	if (skb->len > tcp_hdrlen(skb))
2328  		WRITE_ONCE(tp->data_segs_in, tp->data_segs_in + segs_in);
2329  }
2330  
2331  /*
2332   * TCP listen path runs lockless.
2333   * We forced "struct sock" to be const qualified to make sure
2334   * we don't modify one of its field by mistake.
2335   * Here, we increment sk_drops which is an atomic_t, so we can safely
2336   * make sock writable again.
2337   */
tcp_listendrop(const struct sock * sk)2338  static inline void tcp_listendrop(const struct sock *sk)
2339  {
2340  	atomic_inc(&((struct sock *)sk)->sk_drops);
2341  	__NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
2342  }
2343  
2344  enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
2345  
2346  /*
2347   * Interface for adding Upper Level Protocols over TCP
2348   */
2349  
2350  #define TCP_ULP_NAME_MAX	16
2351  #define TCP_ULP_MAX		128
2352  #define TCP_ULP_BUF_MAX		(TCP_ULP_NAME_MAX*TCP_ULP_MAX)
2353  
2354  struct tcp_ulp_ops {
2355  	struct list_head	list;
2356  
2357  	/* initialize ulp */
2358  	int (*init)(struct sock *sk);
2359  	/* update ulp */
2360  	void (*update)(struct sock *sk, struct proto *p,
2361  		       void (*write_space)(struct sock *sk));
2362  	/* cleanup ulp */
2363  	void (*release)(struct sock *sk);
2364  	/* diagnostic */
2365  	int (*get_info)(struct sock *sk, struct sk_buff *skb);
2366  	size_t (*get_info_size)(const struct sock *sk);
2367  	/* clone ulp */
2368  	void (*clone)(const struct request_sock *req, struct sock *newsk,
2369  		      const gfp_t priority);
2370  
2371  	char		name[TCP_ULP_NAME_MAX];
2372  	struct module	*owner;
2373  };
2374  int tcp_register_ulp(struct tcp_ulp_ops *type);
2375  void tcp_unregister_ulp(struct tcp_ulp_ops *type);
2376  int tcp_set_ulp(struct sock *sk, const char *name);
2377  void tcp_get_available_ulp(char *buf, size_t len);
2378  void tcp_cleanup_ulp(struct sock *sk);
2379  void tcp_update_ulp(struct sock *sk, struct proto *p,
2380  		    void (*write_space)(struct sock *sk));
2381  
2382  #define MODULE_ALIAS_TCP_ULP(name)				\
2383  	__MODULE_INFO(alias, alias_userspace, name);		\
2384  	__MODULE_INFO(alias, alias_tcp_ulp, "tcp-ulp-" name)
2385  
2386  #ifdef CONFIG_NET_SOCK_MSG
2387  struct sk_msg;
2388  struct sk_psock;
2389  
2390  #ifdef CONFIG_BPF_SYSCALL
2391  int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
2392  void tcp_bpf_clone(const struct sock *sk, struct sock *newsk);
2393  #endif /* CONFIG_BPF_SYSCALL */
2394  
2395  #ifdef CONFIG_INET
2396  void tcp_eat_skb(struct sock *sk, struct sk_buff *skb);
2397  #else
tcp_eat_skb(struct sock * sk,struct sk_buff * skb)2398  static inline void tcp_eat_skb(struct sock *sk, struct sk_buff *skb)
2399  {
2400  }
2401  #endif
2402  
2403  int tcp_bpf_sendmsg_redir(struct sock *sk, bool ingress,
2404  			  struct sk_msg *msg, u32 bytes, int flags);
2405  #endif /* CONFIG_NET_SOCK_MSG */
2406  
2407  #if !defined(CONFIG_BPF_SYSCALL) || !defined(CONFIG_NET_SOCK_MSG)
tcp_bpf_clone(const struct sock * sk,struct sock * newsk)2408  static inline void tcp_bpf_clone(const struct sock *sk, struct sock *newsk)
2409  {
2410  }
2411  #endif
2412  
2413  #ifdef CONFIG_CGROUP_BPF
bpf_skops_init_skb(struct bpf_sock_ops_kern * skops,struct sk_buff * skb,unsigned int end_offset)2414  static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops,
2415  				      struct sk_buff *skb,
2416  				      unsigned int end_offset)
2417  {
2418  	skops->skb = skb;
2419  	skops->skb_data_end = skb->data + end_offset;
2420  }
2421  #else
bpf_skops_init_skb(struct bpf_sock_ops_kern * skops,struct sk_buff * skb,unsigned int end_offset)2422  static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops,
2423  				      struct sk_buff *skb,
2424  				      unsigned int end_offset)
2425  {
2426  }
2427  #endif
2428  
2429  /* Call BPF_SOCK_OPS program that returns an int. If the return value
2430   * is < 0, then the BPF op failed (for example if the loaded BPF
2431   * program does not support the chosen operation or there is no BPF
2432   * program loaded).
2433   */
2434  #ifdef CONFIG_BPF
tcp_call_bpf(struct sock * sk,int op,u32 nargs,u32 * args)2435  static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2436  {
2437  	struct bpf_sock_ops_kern sock_ops;
2438  	int ret;
2439  
2440  	memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
2441  	if (sk_fullsock(sk)) {
2442  		sock_ops.is_fullsock = 1;
2443  		sock_owned_by_me(sk);
2444  	}
2445  
2446  	sock_ops.sk = sk;
2447  	sock_ops.op = op;
2448  	if (nargs > 0)
2449  		memcpy(sock_ops.args, args, nargs * sizeof(*args));
2450  
2451  	ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops);
2452  	if (ret == 0)
2453  		ret = sock_ops.reply;
2454  	else
2455  		ret = -1;
2456  	return ret;
2457  }
2458  
tcp_call_bpf_2arg(struct sock * sk,int op,u32 arg1,u32 arg2)2459  static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2460  {
2461  	u32 args[2] = {arg1, arg2};
2462  
2463  	return tcp_call_bpf(sk, op, 2, args);
2464  }
2465  
tcp_call_bpf_3arg(struct sock * sk,int op,u32 arg1,u32 arg2,u32 arg3)2466  static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2467  				    u32 arg3)
2468  {
2469  	u32 args[3] = {arg1, arg2, arg3};
2470  
2471  	return tcp_call_bpf(sk, op, 3, args);
2472  }
2473  
2474  #else
tcp_call_bpf(struct sock * sk,int op,u32 nargs,u32 * args)2475  static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2476  {
2477  	return -EPERM;
2478  }
2479  
tcp_call_bpf_2arg(struct sock * sk,int op,u32 arg1,u32 arg2)2480  static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2481  {
2482  	return -EPERM;
2483  }
2484  
tcp_call_bpf_3arg(struct sock * sk,int op,u32 arg1,u32 arg2,u32 arg3)2485  static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2486  				    u32 arg3)
2487  {
2488  	return -EPERM;
2489  }
2490  
2491  #endif
2492  
tcp_timeout_init(struct sock * sk)2493  static inline u32 tcp_timeout_init(struct sock *sk)
2494  {
2495  	int timeout;
2496  
2497  	timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT, 0, NULL);
2498  
2499  	if (timeout <= 0)
2500  		timeout = TCP_TIMEOUT_INIT;
2501  	return min_t(int, timeout, TCP_RTO_MAX);
2502  }
2503  
tcp_rwnd_init_bpf(struct sock * sk)2504  static inline u32 tcp_rwnd_init_bpf(struct sock *sk)
2505  {
2506  	int rwnd;
2507  
2508  	rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL);
2509  
2510  	if (rwnd < 0)
2511  		rwnd = 0;
2512  	return rwnd;
2513  }
2514  
tcp_bpf_ca_needs_ecn(struct sock * sk)2515  static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)
2516  {
2517  	return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1);
2518  }
2519  
tcp_bpf_rtt(struct sock * sk)2520  static inline void tcp_bpf_rtt(struct sock *sk)
2521  {
2522  	if (BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), BPF_SOCK_OPS_RTT_CB_FLAG))
2523  		tcp_call_bpf(sk, BPF_SOCK_OPS_RTT_CB, 0, NULL);
2524  }
2525  
2526  #if IS_ENABLED(CONFIG_SMC)
2527  extern struct static_key_false tcp_have_smc;
2528  #endif
2529  
2530  #if IS_ENABLED(CONFIG_TLS_DEVICE)
2531  void clean_acked_data_enable(struct inet_connection_sock *icsk,
2532  			     void (*cad)(struct sock *sk, u32 ack_seq));
2533  void clean_acked_data_disable(struct inet_connection_sock *icsk);
2534  void clean_acked_data_flush(void);
2535  #endif
2536  
2537  DECLARE_STATIC_KEY_FALSE(tcp_tx_delay_enabled);
tcp_add_tx_delay(struct sk_buff * skb,const struct tcp_sock * tp)2538  static inline void tcp_add_tx_delay(struct sk_buff *skb,
2539  				    const struct tcp_sock *tp)
2540  {
2541  	if (static_branch_unlikely(&tcp_tx_delay_enabled))
2542  		skb->skb_mstamp_ns += (u64)tp->tcp_tx_delay * NSEC_PER_USEC;
2543  }
2544  
2545  /* Compute Earliest Departure Time for some control packets
2546   * like ACK or RST for TIME_WAIT or non ESTABLISHED sockets.
2547   */
tcp_transmit_time(const struct sock * sk)2548  static inline u64 tcp_transmit_time(const struct sock *sk)
2549  {
2550  	if (static_branch_unlikely(&tcp_tx_delay_enabled)) {
2551  		u32 delay = (sk->sk_state == TCP_TIME_WAIT) ?
2552  			tcp_twsk(sk)->tw_tx_delay : tcp_sk(sk)->tcp_tx_delay;
2553  
2554  		return tcp_clock_ns() + (u64)delay * NSEC_PER_USEC;
2555  	}
2556  	return 0;
2557  }
2558  
2559  #endif	/* _TCP_H */
2560