tcp.h 62.4 KB
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/*
 * INET		An implementation of the TCP/IP protocol suite for the LINUX
 *		operating system.  INET is implemented using the  BSD Socket
 *		interface as the means of communication with the user level.
 *
 *		Definitions for the TCP module.
 *
 * Version:	@(#)tcp.h	1.0.5	05/23/93
 *
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 * Authors:	Ross Biro
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 *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 */
#ifndef _TCP_H
#define _TCP_H

#define FASTRETRANS_DEBUG 1

#include <linux/list.h>
#include <linux/tcp.h>
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#include <linux/bug.h>
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#include <linux/slab.h>
#include <linux/cache.h>
#include <linux/percpu.h>
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#include <linux/skbuff.h>
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#include <linux/cryptohash.h>
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#include <linux/kref.h>
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#include <linux/ktime.h>
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#include <net/inet_connection_sock.h>
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#include <net/inet_timewait_sock.h>
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#include <net/inet_hashtables.h>
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#include <net/checksum.h>
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#include <net/request_sock.h>
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#include <net/sock.h>
#include <net/snmp.h>
#include <net/ip.h>
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#include <net/tcp_states.h>
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#include <net/inet_ecn.h>
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#include <net/dst.h>
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#include <linux/seq_file.h>
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#include <linux/memcontrol.h>
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#include <linux/bpf.h>
#include <linux/filter.h>
#include <linux/bpf-cgroup.h>

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extern struct inet_hashinfo tcp_hashinfo;
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extern struct percpu_counter tcp_orphan_count;
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void tcp_time_wait(struct sock *sk, int state, int timeo);
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#define MAX_TCP_HEADER	(128 + MAX_HEADER)
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#define MAX_TCP_OPTION_SPACE 40
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/*
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 * Never offer a window over 32767 without using window scaling. Some
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 * poor stacks do signed 16bit maths!
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 */
#define MAX_TCP_WINDOW		32767U

/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
#define TCP_MIN_MSS		88U

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/* The least MTU to use for probing */
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#define TCP_BASE_MSS		1024
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/* probing interval, default to 10 minutes as per RFC4821 */
#define TCP_PROBE_INTERVAL	600

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/* Specify interval when tcp mtu probing will stop */
#define TCP_PROBE_THRESHOLD	8

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/* After receiving this amount of duplicate ACKs fast retransmit starts. */
#define TCP_FASTRETRANS_THRESH 3

/* Maximal number of ACKs sent quickly to accelerate slow-start. */
#define TCP_MAX_QUICKACKS	16U

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/* Maximal number of window scale according to RFC1323 */
#define TCP_MAX_WSCALE		14U

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/* urg_data states */
#define TCP_URG_VALID	0x0100
#define TCP_URG_NOTYET	0x0200
#define TCP_URG_READ	0x0400

#define TCP_RETR1	3	/*
				 * This is how many retries it does before it
				 * tries to figure out if the gateway is
				 * down. Minimal RFC value is 3; it corresponds
				 * to ~3sec-8min depending on RTO.
				 */

#define TCP_RETR2	15	/*
				 * This should take at least
				 * 90 minutes to time out.
				 * RFC1122 says that the limit is 100 sec.
				 * 15 is ~13-30min depending on RTO.
				 */

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#define TCP_SYN_RETRIES	 6	/* This is how many retries are done
				 * when active opening a connection.
				 * RFC1122 says the minimum retry MUST
				 * be at least 180secs.  Nevertheless
				 * this value is corresponding to
				 * 63secs of retransmission with the
				 * current initial RTO.
				 */
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#define TCP_SYNACK_RETRIES 5	/* This is how may retries are done
				 * when passive opening a connection.
				 * This is corresponding to 31secs of
				 * retransmission with the current
				 * initial RTO.
				 */
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#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
				  * state, about 60 seconds	*/
#define TCP_FIN_TIMEOUT	TCP_TIMEWAIT_LEN
                                 /* BSD style FIN_WAIT2 deadlock breaker.
				  * It used to be 3min, new value is 60sec,
				  * to combine FIN-WAIT-2 timeout with
				  * TIME-WAIT timer.
				  */

#define TCP_DELACK_MAX	((unsigned)(HZ/5))	/* maximal time to delay before sending an ACK */
#if HZ >= 100
#define TCP_DELACK_MIN	((unsigned)(HZ/25))	/* minimal time to delay before sending an ACK */
#define TCP_ATO_MIN	((unsigned)(HZ/25))
#else
#define TCP_DELACK_MIN	4U
#define TCP_ATO_MIN	4U
#endif
#define TCP_RTO_MAX	((unsigned)(120*HZ))
#define TCP_RTO_MIN	((unsigned)(HZ/5))
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#define TCP_TIMEOUT_MIN	(2U) /* Min timeout for TCP timers in jiffies */
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#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ))	/* RFC6298 2.1 initial RTO value	*/
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#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ))	/* RFC 1122 initial RTO value, now
						 * used as a fallback RTO for the
						 * initial data transmission if no
						 * valid RTT sample has been acquired,
						 * most likely due to retrans in 3WHS.
						 */
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#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
					                 * for local resources.
					                 */
#define TCP_KEEPALIVE_TIME	(120*60*HZ)	/* two hours */
#define TCP_KEEPALIVE_PROBES	9		/* Max of 9 keepalive probes	*/
#define TCP_KEEPALIVE_INTVL	(75*HZ)

#define MAX_TCP_KEEPIDLE	32767
#define MAX_TCP_KEEPINTVL	32767
#define MAX_TCP_KEEPCNT		127
#define MAX_TCP_SYNCNT		127

#define TCP_SYNQ_INTERVAL	(HZ/5)	/* Period of SYNACK timer */

#define TCP_PAWS_24DAYS	(60 * 60 * 24 * 24)
#define TCP_PAWS_MSL	60		/* Per-host timestamps are invalidated
					 * after this time. It should be equal
					 * (or greater than) TCP_TIMEWAIT_LEN
					 * to provide reliability equal to one
					 * provided by timewait state.
					 */
#define TCP_PAWS_WINDOW	1		/* Replay window for per-host
					 * timestamps. It must be less than
					 * minimal timewait lifetime.
					 */
/*
 *	TCP option
 */
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#define TCPOPT_NOP		1	/* Padding */
#define TCPOPT_EOL		0	/* End of options */
#define TCPOPT_MSS		2	/* Segment size negotiating */
#define TCPOPT_WINDOW		3	/* Window scaling */
#define TCPOPT_SACK_PERM        4       /* SACK Permitted */
#define TCPOPT_SACK             5       /* SACK Block */
#define TCPOPT_TIMESTAMP	8	/* Better RTT estimations/PAWS */
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#define TCPOPT_MD5SIG		19	/* MD5 Signature (RFC2385) */
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#define TCPOPT_FASTOPEN		34	/* Fast open (RFC7413) */
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#define TCPOPT_EXP		254	/* Experimental */
/* Magic number to be after the option value for sharing TCP
 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
 */
#define TCPOPT_FASTOPEN_MAGIC	0xF989
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#define TCPOPT_SMC_MAGIC	0xE2D4C3D9
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/*
 *     TCP option lengths
 */

#define TCPOLEN_MSS            4
#define TCPOLEN_WINDOW         3
#define TCPOLEN_SACK_PERM      2
#define TCPOLEN_TIMESTAMP      10
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#define TCPOLEN_MD5SIG         18
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#define TCPOLEN_FASTOPEN_BASE  2
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#define TCPOLEN_EXP_FASTOPEN_BASE  4
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#define TCPOLEN_EXP_SMC_BASE   6
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/* But this is what stacks really send out. */
#define TCPOLEN_TSTAMP_ALIGNED		12
#define TCPOLEN_WSCALE_ALIGNED		4
#define TCPOLEN_SACKPERM_ALIGNED	4
#define TCPOLEN_SACK_BASE		2
#define TCPOLEN_SACK_BASE_ALIGNED	4
#define TCPOLEN_SACK_PERBLOCK		8
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#define TCPOLEN_MD5SIG_ALIGNED		20
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#define TCPOLEN_MSS_ALIGNED		4
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#define TCPOLEN_EXP_SMC_BASE_ALIGNED	8
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/* Flags in tp->nonagle */
#define TCP_NAGLE_OFF		1	/* Nagle's algo is disabled */
#define TCP_NAGLE_CORK		2	/* Socket is corked	    */
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#define TCP_NAGLE_PUSH		4	/* Cork is overridden for already queued data */
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/* TCP thin-stream limits */
#define TCP_THIN_LINEAR_RETRIES 6       /* After 6 linear retries, do exp. backoff */

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/* TCP initial congestion window as per rfc6928 */
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#define TCP_INIT_CWND		10

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/* Bit Flags for sysctl_tcp_fastopen */
#define	TFO_CLIENT_ENABLE	1
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#define	TFO_SERVER_ENABLE	2
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#define	TFO_CLIENT_NO_COOKIE	4	/* Data in SYN w/o cookie option */
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/* Accept SYN data w/o any cookie option */
#define	TFO_SERVER_COOKIE_NOT_REQD	0x200

/* Force enable TFO on all listeners, i.e., not requiring the
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 * TCP_FASTOPEN socket option.
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 */
#define	TFO_SERVER_WO_SOCKOPT1	0x400

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/* sysctl variables for tcp */
extern int sysctl_tcp_max_orphans;
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extern long sysctl_tcp_mem[3];
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extern int sysctl_tcp_wmem[3];
extern int sysctl_tcp_rmem[3];
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#define TCP_RACK_LOSS_DETECTION  0x1 /* Use RACK to detect losses */

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extern int sysctl_tcp_limit_output_bytes;
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extern int sysctl_tcp_challenge_ack_limit;
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extern int sysctl_tcp_min_tso_segs;
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extern int sysctl_tcp_min_rtt_wlen;
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extern int sysctl_tcp_autocorking;
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extern int sysctl_tcp_invalid_ratelimit;
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extern int sysctl_tcp_pacing_ss_ratio;
extern int sysctl_tcp_pacing_ca_ratio;
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extern atomic_long_t tcp_memory_allocated;
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extern struct percpu_counter tcp_sockets_allocated;
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extern unsigned long tcp_memory_pressure;
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/* optimized version of sk_under_memory_pressure() for TCP sockets */
static inline bool tcp_under_memory_pressure(const struct sock *sk)
{
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	if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
	    mem_cgroup_under_socket_pressure(sk->sk_memcg))
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		return true;
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	return tcp_memory_pressure;
}
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/*
 * The next routines deal with comparing 32 bit unsigned ints
 * and worry about wraparound (automatic with unsigned arithmetic).
 */

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static inline bool before(__u32 seq1, __u32 seq2)
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{
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        return (__s32)(seq1-seq2) < 0;
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}
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#define after(seq2, seq1) 	before(seq1, seq2)
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/* is s2<=s1<=s3 ? */
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static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
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{
	return seq3 - seq2 >= seq1 - seq2;
}

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static inline bool tcp_out_of_memory(struct sock *sk)
{
	if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
	    sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
		return true;
	return false;
}

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void sk_forced_mem_schedule(struct sock *sk, int size);

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static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
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{
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	struct percpu_counter *ocp = sk->sk_prot->orphan_count;
	int orphans = percpu_counter_read_positive(ocp);

	if (orphans << shift > sysctl_tcp_max_orphans) {
		orphans = percpu_counter_sum_positive(ocp);
		if (orphans << shift > sysctl_tcp_max_orphans)
			return true;
	}
	return false;
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}
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bool tcp_check_oom(struct sock *sk, int shift);
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extern struct proto tcp_prot;

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#define TCP_INC_STATS(net, field)	SNMP_INC_STATS((net)->mib.tcp_statistics, field)
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#define __TCP_INC_STATS(net, field)	__SNMP_INC_STATS((net)->mib.tcp_statistics, field)
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#define TCP_DEC_STATS(net, field)	SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
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#define TCP_ADD_STATS(net, field, val)	SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
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void tcp_tasklet_init(void);

void tcp_v4_err(struct sk_buff *skb, u32);

void tcp_shutdown(struct sock *sk, int how);

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int tcp_v4_early_demux(struct sk_buff *skb);
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int tcp_v4_rcv(struct sk_buff *skb);

int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
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int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
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int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size);
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int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
		 int flags);
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int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset,
			size_t size, int flags);
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ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
		 size_t size, int flags);
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void tcp_release_cb(struct sock *sk);
void tcp_wfree(struct sk_buff *skb);
void tcp_write_timer_handler(struct sock *sk);
void tcp_delack_timer_handler(struct sock *sk);
int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
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int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
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void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
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			 const struct tcphdr *th);
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void tcp_rcv_space_adjust(struct sock *sk);
int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
void tcp_twsk_destructor(struct sock *sk);
ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
			struct pipe_inode_info *pipe, size_t len,
			unsigned int flags);
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static inline void tcp_dec_quickack_mode(struct sock *sk,
					 const unsigned int pkts)
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{
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	struct inet_connection_sock *icsk = inet_csk(sk);
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	if (icsk->icsk_ack.quick) {
		if (pkts >= icsk->icsk_ack.quick) {
			icsk->icsk_ack.quick = 0;
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			/* Leaving quickack mode we deflate ATO. */
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			icsk->icsk_ack.ato   = TCP_ATO_MIN;
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		} else
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			icsk->icsk_ack.quick -= pkts;
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	}
}

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#define	TCP_ECN_OK		1
#define	TCP_ECN_QUEUE_CWR	2
#define	TCP_ECN_DEMAND_CWR	4
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#define	TCP_ECN_SEEN		8
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enum tcp_tw_status {
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	TCP_TW_SUCCESS = 0,
	TCP_TW_RST = 1,
	TCP_TW_ACK = 2,
	TCP_TW_SYN = 3
};


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enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
					      struct sk_buff *skb,
					      const struct tcphdr *th);
struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
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			   struct request_sock *req, bool fastopen);
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int tcp_child_process(struct sock *parent, struct sock *child,
		      struct sk_buff *skb);
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void tcp_enter_loss(struct sock *sk);
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void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int flag);
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void tcp_clear_retrans(struct tcp_sock *tp);
void tcp_update_metrics(struct sock *sk);
void tcp_init_metrics(struct sock *sk);
void tcp_metrics_init(void);
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bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst);
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void tcp_disable_fack(struct tcp_sock *tp);
void tcp_close(struct sock *sk, long timeout);
void tcp_init_sock(struct sock *sk);
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void tcp_init_transfer(struct sock *sk, int bpf_op);
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unsigned int tcp_poll(struct file *file, struct socket *sock,
		      struct poll_table_struct *wait);
int tcp_getsockopt(struct sock *sk, int level, int optname,
		   char __user *optval, int __user *optlen);
int tcp_setsockopt(struct sock *sk, int level, int optname,
		   char __user *optval, unsigned int optlen);
int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
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			  char __user *optval, int __user *optlen);
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int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
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			  char __user *optval, unsigned int optlen);
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void tcp_set_keepalive(struct sock *sk, int val);
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void tcp_syn_ack_timeout(const struct request_sock *req);
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int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
		int flags, int *addr_len);
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void tcp_parse_options(const struct net *net, const struct sk_buff *skb,
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		       struct tcp_options_received *opt_rx,
		       int estab, struct tcp_fastopen_cookie *foc);
const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
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/*
 *	TCP v4 functions exported for the inet6 API
 */

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void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
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void tcp_v4_mtu_reduced(struct sock *sk);
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void tcp_req_err(struct sock *sk, u32 seq, bool abort);
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int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
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struct sock *tcp_create_openreq_child(const struct sock *sk,
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				      struct request_sock *req,
				      struct sk_buff *skb);
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void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
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struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
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				  struct request_sock *req,
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				  struct dst_entry *dst,
				  struct request_sock *req_unhash,
				  bool *own_req);
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int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
int tcp_connect(struct sock *sk);
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enum tcp_synack_type {
	TCP_SYNACK_NORMAL,
	TCP_SYNACK_FASTOPEN,
	TCP_SYNACK_COOKIE,
};
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struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
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				struct request_sock *req,
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				struct tcp_fastopen_cookie *foc,
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				enum tcp_synack_type synack_type);
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int tcp_disconnect(struct sock *sk, int flags);
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void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
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int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
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void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
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/* From syncookies.c */
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struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
				 struct request_sock *req,
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				 struct dst_entry *dst, u32 tsoff);
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int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
		      u32 cookie);
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struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
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#ifdef CONFIG_SYN_COOKIES
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/* Syncookies use a monotonic timer which increments every 60 seconds.
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 * This counter is used both as a hash input and partially encoded into
 * the cookie value.  A cookie is only validated further if the delta
 * between the current counter value and the encoded one is less than this,
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 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
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 * the counter advances immediately after a cookie is generated).
 */
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#define MAX_SYNCOOKIE_AGE	2
#define TCP_SYNCOOKIE_PERIOD	(60 * HZ)
#define TCP_SYNCOOKIE_VALID	(MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)

/* syncookies: remember time of last synqueue overflow
 * But do not dirty this field too often (once per second is enough)
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 * It is racy as we do not hold a lock, but race is very minor.
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 */
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static inline void tcp_synq_overflow(const struct sock *sk)
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{
	unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
	unsigned long now = jiffies;

	if (time_after(now, last_overflow + HZ))
		tcp_sk(sk)->rx_opt.ts_recent_stamp = now;
}

/* syncookies: no recent synqueue overflow on this listening socket? */
static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
{
	unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;

	return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID);
}
498 499 500

static inline u32 tcp_cookie_time(void)
{
501 502
	u64 val = get_jiffies_64();

503
	do_div(val, TCP_SYNCOOKIE_PERIOD);
504
	return val;
505 506
}

507 508
u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
			      u16 *mssp);
509
__u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
510
u64 cookie_init_timestamp(struct request_sock *req);
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Eric Dumazet 已提交
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bool cookie_timestamp_decode(const struct net *net,
			     struct tcp_options_received *opt);
513
bool cookie_ecn_ok(const struct tcp_options_received *opt,
514
		   const struct net *net, const struct dst_entry *dst);
515

516
/* From net/ipv6/syncookies.c */
517 518 519
int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
		      u32 cookie);
struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
520

521 522
u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
			      const struct tcphdr *th, u16 *mssp);
523
__u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
524
#endif
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/* tcp_output.c */

527 528
u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,
		     int min_tso_segs);
529 530
void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
			       int nonagle);
531 532
int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
533 534 535
void tcp_retransmit_timer(struct sock *sk);
void tcp_xmit_retransmit_queue(struct sock *);
void tcp_simple_retransmit(struct sock *);
536
void tcp_enter_recovery(struct sock *sk, bool ece_ack);
537
int tcp_trim_head(struct sock *, struct sk_buff *, u32);
538 539 540 541 542 543 544
enum tcp_queue {
	TCP_FRAG_IN_WRITE_QUEUE,
	TCP_FRAG_IN_RTX_QUEUE,
};
int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
		 struct sk_buff *skb, u32 len,
		 unsigned int mss_now, gfp_t gfp);
545 546 547

void tcp_send_probe0(struct sock *);
void tcp_send_partial(struct sock *);
548
int tcp_write_wakeup(struct sock *, int mib);
549 550 551 552 553 554 555 556
void tcp_send_fin(struct sock *sk);
void tcp_send_active_reset(struct sock *sk, gfp_t priority);
int tcp_send_synack(struct sock *);
void tcp_push_one(struct sock *, unsigned int mss_now);
void tcp_send_ack(struct sock *sk);
void tcp_send_delayed_ack(struct sock *sk);
void tcp_send_loss_probe(struct sock *sk);
bool tcp_schedule_loss_probe(struct sock *sk);
557 558
void tcp_skb_collapse_tstamp(struct sk_buff *skb,
			     const struct sk_buff *next_skb);
L
Linus Torvalds 已提交
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560
/* tcp_input.c */
561
void tcp_rearm_rto(struct sock *sk);
Y
Yuchung Cheng 已提交
562
void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
563
void tcp_reset(struct sock *sk);
Y
Yuchung Cheng 已提交
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void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
565
void tcp_fin(struct sock *sk);
566

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/* tcp_timer.c */
568
void tcp_init_xmit_timers(struct sock *);
569 570
static inline void tcp_clear_xmit_timers(struct sock *sk)
{
571
	hrtimer_cancel(&tcp_sk(sk)->pacing_timer);
572 573
	inet_csk_clear_xmit_timers(sk);
}
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574

575 576
unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
unsigned int tcp_current_mss(struct sock *sk);
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/* Bound MSS / TSO packet size with the half of the window */
static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
{
581 582 583 584 585 586 587 588 589
	int cutoff;

	/* When peer uses tiny windows, there is no use in packetizing
	 * to sub-MSS pieces for the sake of SWS or making sure there
	 * are enough packets in the pipe for fast recovery.
	 *
	 * On the other hand, for extremely large MSS devices, handling
	 * smaller than MSS windows in this way does make sense.
	 */
590
	if (tp->max_window > TCP_MSS_DEFAULT)
591 592 593 594 595 596
		cutoff = (tp->max_window >> 1);
	else
		cutoff = tp->max_window;

	if (cutoff && pktsize > cutoff)
		return max_t(int, cutoff, 68U - tp->tcp_header_len);
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	else
		return pktsize;
}
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600

601
/* tcp.c */
602
void tcp_get_info(struct sock *, struct tcp_info *);
L
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/* Read 'sendfile()'-style from a TCP socket */
605 606
int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
		  sk_read_actor_t recv_actor);
L
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607

608
void tcp_initialize_rcv_mss(struct sock *sk);
L
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610 611 612 613
int tcp_mtu_to_mss(struct sock *sk, int pmtu);
int tcp_mss_to_mtu(struct sock *sk, int mss);
void tcp_mtup_init(struct sock *sk);
void tcp_init_buffer_space(struct sock *sk);
J
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615 616 617 618 619 620 621 622
static inline void tcp_bound_rto(const struct sock *sk)
{
	if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
		inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
}

static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
{
623
	return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
624 625
}

626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648
static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
{
	tp->pred_flags = htonl((tp->tcp_header_len << 26) |
			       ntohl(TCP_FLAG_ACK) |
			       snd_wnd);
}

static inline void tcp_fast_path_on(struct tcp_sock *tp)
{
	__tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
}

static inline void tcp_fast_path_check(struct sock *sk)
{
	struct tcp_sock *tp = tcp_sk(sk);

	if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
	    tp->rcv_wnd &&
	    atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
	    !tp->urg_data)
		tcp_fast_path_on(tp);
}

649 650 651
/* Compute the actual rto_min value */
static inline u32 tcp_rto_min(struct sock *sk)
{
652
	const struct dst_entry *dst = __sk_dst_get(sk);
653 654 655 656 657 658 659
	u32 rto_min = TCP_RTO_MIN;

	if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
		rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
	return rto_min;
}

660 661 662 663 664
static inline u32 tcp_rto_min_us(struct sock *sk)
{
	return jiffies_to_usecs(tcp_rto_min(sk));
}

665 666 667 668 669
static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
{
	return dst_metric_locked(dst, RTAX_CC_ALGO);
}

670 671 672
/* Minimum RTT in usec. ~0 means not available. */
static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
{
673
	return minmax_get(&tp->rtt_min);
674 675
}

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/* Compute the actual receive window we are currently advertising.
 * Rcv_nxt can be after the window if our peer push more data
 * than the offered window.
 */
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680
static inline u32 tcp_receive_window(const struct tcp_sock *tp)
L
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681 682 683 684 685 686 687 688 689 690 691 692
{
	s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;

	if (win < 0)
		win = 0;
	return (u32) win;
}

/* Choose a new window, without checks for shrinking, and without
 * scaling applied to the result.  The caller does these things
 * if necessary.  This is a "raw" window selection.
 */
693
u32 __tcp_select_window(struct sock *sk);
L
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694

P
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void tcp_send_window_probe(struct sock *sk);

E
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/* TCP uses 32bit jiffies to save some space.
 * Note that this is different from tcp_time_stamp, which
 * historically has been the same until linux-4.13.
 */
#define tcp_jiffies32 ((u32)jiffies)

703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734
/*
 * Deliver a 32bit value for TCP timestamp option (RFC 7323)
 * It is no longer tied to jiffies, but to 1 ms clock.
 * Note: double check if you want to use tcp_jiffies32 instead of this.
 */
#define TCP_TS_HZ	1000

static inline u64 tcp_clock_ns(void)
{
	return local_clock();
}

static inline u64 tcp_clock_us(void)
{
	return div_u64(tcp_clock_ns(), NSEC_PER_USEC);
}

/* This should only be used in contexts where tp->tcp_mstamp is up to date */
static inline u32 tcp_time_stamp(const struct tcp_sock *tp)
{
	return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ);
}

/* Could use tcp_clock_us() / 1000, but this version uses a single divide */
static inline u32 tcp_time_stamp_raw(void)
{
	return div_u64(tcp_clock_ns(), NSEC_PER_SEC / TCP_TS_HZ);
}


/* Refresh 1us clock of a TCP socket,
 * ensuring monotically increasing values.
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 */
736 737 738 739 740 741 742 743 744 745 746 747
static inline void tcp_mstamp_refresh(struct tcp_sock *tp)
{
	u64 val = tcp_clock_us();

	if (val > tp->tcp_mstamp)
		tp->tcp_mstamp = val;
}

static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
{
	return max_t(s64, t1 - t0, 0);
}
L
Linus Torvalds 已提交
748

E
Eric Dumazet 已提交
749 750
static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
{
751
	return div_u64(skb->skb_mstamp, USEC_PER_SEC / TCP_TS_HZ);
E
Eric Dumazet 已提交
752 753 754
}


C
Changli Gao 已提交
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#define tcp_flag_byte(th) (((u_int8_t *)th)[13])

#define TCPHDR_FIN 0x01
#define TCPHDR_SYN 0x02
#define TCPHDR_RST 0x04
#define TCPHDR_PSH 0x08
#define TCPHDR_ACK 0x10
#define TCPHDR_URG 0x20
#define TCPHDR_ECE 0x40
#define TCPHDR_CWR 0x80

766 767
#define TCPHDR_SYN_ECN	(TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)

S
Stephen Hemminger 已提交
768
/* This is what the send packet queuing engine uses to pass
769 770 771 772
 * TCP per-packet control information to the transmission code.
 * We also store the host-order sequence numbers in here too.
 * This is 44 bytes if IPV6 is enabled.
 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
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 */
struct tcp_skb_cb {
	__u32		seq;		/* Starting sequence number	*/
	__u32		end_seq;	/* SEQ + FIN + SYN + datalen	*/
777 778 779 780
	union {
		/* Note : tcp_tw_isn is used in input path only
		 *	  (isn chosen by tcp_timewait_state_process())
		 *
781 782
		 * 	  tcp_gso_segs/size are used in write queue only,
		 *	  cf tcp_skb_pcount()/tcp_skb_mss()
783 784
		 */
		__u32		tcp_tw_isn;
785 786 787 788
		struct {
			u16	tcp_gso_segs;
			u16	tcp_gso_size;
		};
789
	};
E
Eric Dumazet 已提交
790
	__u8		tcp_flags;	/* TCP header flags. (tcp[13])	*/
791

L
Linus Torvalds 已提交
792 793 794 795 796
	__u8		sacked;		/* State flags for SACK/FACK.	*/
#define TCPCB_SACKED_ACKED	0x01	/* SKB ACK'd by a SACK block	*/
#define TCPCB_SACKED_RETRANS	0x02	/* SKB retransmitted		*/
#define TCPCB_LOST		0x04	/* SKB is lost			*/
#define TCPCB_TAGBITS		0x07	/* All tag bits			*/
797
#define TCPCB_REPAIRED		0x10	/* SKB repaired (no skb_mstamp)	*/
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798
#define TCPCB_EVER_RETRANS	0x80	/* Ever retransmitted frame	*/
799 800
#define TCPCB_RETRANS		(TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
				TCPCB_REPAIRED)
L
Linus Torvalds 已提交
801

802
	__u8		ip_dsfield;	/* IPv4 tos or IPv6 dsfield	*/
803
	__u8		txstamp_ack:1,	/* Record TX timestamp for ack? */
804
			eor:1,		/* Is skb MSG_EOR marked? */
805 806
			has_rxtstamp:1,	/* SKB has a RX timestamp	*/
			unused:5;
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Linus Torvalds 已提交
807
	__u32		ack_seq;	/* Sequence number ACK'd	*/
808
	union {
809
		struct {
810
			/* There is space for up to 24 bytes */
811 812 813
			__u32 in_flight:30,/* Bytes in flight at transmit */
			      is_app_limited:1, /* cwnd not fully used? */
			      unused:1;
814 815 816
			/* pkts S/ACKed so far upon tx of skb, incl retrans: */
			__u32 delivered;
			/* start of send pipeline phase */
817
			u64 first_tx_mstamp;
818
			/* when we reached the "delivered" count */
819
			u64 delivered_mstamp;
820 821 822
		} tx;   /* only used for outgoing skbs */
		union {
			struct inet_skb_parm	h4;
823
#if IS_ENABLED(CONFIG_IPV6)
824
			struct inet6_skb_parm	h6;
825
#endif
826
		} header;	/* For incoming skbs */
827 828 829 830 831
		struct {
			__u32 key;
			__u32 flags;
			struct bpf_map *map;
		} bpf;
832
	};
L
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833 834 835 836
};

#define TCP_SKB_CB(__skb)	((struct tcp_skb_cb *)&((__skb)->cb[0]))

E
Eric Dumazet 已提交
837

838
#if IS_ENABLED(CONFIG_IPV6)
E
Eric Dumazet 已提交
839 840 841 842 843
/* This is the variant of inet6_iif() that must be used by TCP,
 * as TCP moves IP6CB into a different location in skb->cb[]
 */
static inline int tcp_v6_iif(const struct sk_buff *skb)
{
844
	bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
845 846

	return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
E
Eric Dumazet 已提交
847
}
848 849 850 851 852 853 854 855 856 857

/* TCP_SKB_CB reference means this can not be used from early demux */
static inline int tcp_v6_sdif(const struct sk_buff *skb)
{
#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
	if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags))
		return TCP_SKB_CB(skb)->header.h6.iif;
#endif
	return 0;
}
858
#endif
E
Eric Dumazet 已提交
859

860 861 862 863 864
/* TCP_SKB_CB reference means this can not be used from early demux */
static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb)
{
#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
	if (!net->ipv4.sysctl_tcp_l3mdev_accept &&
865
	    skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
866 867 868 869 870
		return true;
#endif
	return false;
}

871 872 873 874 875 876 877 878 879 880
/* TCP_SKB_CB reference means this can not be used from early demux */
static inline int tcp_v4_sdif(struct sk_buff *skb)
{
#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
	if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
		return TCP_SKB_CB(skb)->header.h4.iif;
#endif
	return 0;
}

L
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881 882
/* Due to TSO, an SKB can be composed of multiple actual
 * packets.  To keep these tracked properly, we use this.
883
 */
L
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884
static inline int tcp_skb_pcount(const struct sk_buff *skb)
885
{
886 887
	return TCP_SKB_CB(skb)->tcp_gso_segs;
}
888

889 890 891
static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
{
	TCP_SKB_CB(skb)->tcp_gso_segs = segs;
892 893
}

894
static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
L
Linus Torvalds 已提交
895
{
896
	TCP_SKB_CB(skb)->tcp_gso_segs += segs;
L
Linus Torvalds 已提交
897 898
}

899
/* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
L
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900 901
static inline int tcp_skb_mss(const struct sk_buff *skb)
{
902
	return TCP_SKB_CB(skb)->tcp_gso_size;
L
Linus Torvalds 已提交
903 904
}

905 906 907 908 909
static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
{
	return likely(!TCP_SKB_CB(skb)->eor);
}

910 911 912 913 914 915
/* Events passed to congestion control interface */
enum tcp_ca_event {
	CA_EVENT_TX_START,	/* first transmit when no packets in flight */
	CA_EVENT_CWND_RESTART,	/* congestion window restart */
	CA_EVENT_COMPLETE_CWR,	/* end of congestion recovery */
	CA_EVENT_LOSS,		/* loss timeout */
916 917 918 919
	CA_EVENT_ECN_NO_CE,	/* ECT set, but not CE marked */
	CA_EVENT_ECN_IS_CE,	/* received CE marked IP packet */
	CA_EVENT_DELAYED_ACK,	/* Delayed ack is sent */
	CA_EVENT_NON_DELAYED_ACK,
920 921
};

922
/* Information about inbound ACK, passed to cong_ops->in_ack_event() */
923
enum tcp_ca_ack_event_flags {
924 925 926
	CA_ACK_SLOWPATH		= (1 << 0),	/* In slow path processing */
	CA_ACK_WIN_UPDATE	= (1 << 1),	/* ACK updated window */
	CA_ACK_ECE		= (1 << 2),	/* ECE bit is set on ack */
927 928 929 930 931 932
};

/*
 * Interface for adding new TCP congestion control handlers
 */
#define TCP_CA_NAME_MAX	16
933 934 935
#define TCP_CA_MAX	128
#define TCP_CA_BUF_MAX	(TCP_CA_NAME_MAX*TCP_CA_MAX)

936 937
#define TCP_CA_UNSPEC	0

938
/* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
939
#define TCP_CONG_NON_RESTRICTED 0x1
940 941
/* Requires ECN/ECT set on all packets */
#define TCP_CONG_NEEDS_ECN	0x2
942

943 944
union tcp_cc_info;

945 946 947
struct ack_sample {
	u32 pkts_acked;
	s32 rtt_us;
948
	u32 in_flight;
949 950
};

951 952 953 954 955 956 957 958 959
/* A rate sample measures the number of (original/retransmitted) data
 * packets delivered "delivered" over an interval of time "interval_us".
 * The tcp_rate.c code fills in the rate sample, and congestion
 * control modules that define a cong_control function to run at the end
 * of ACK processing can optionally chose to consult this sample when
 * setting cwnd and pacing rate.
 * A sample is invalid if "delivered" or "interval_us" is negative.
 */
struct rate_sample {
960
	u64  prior_mstamp; /* starting timestamp for interval */
961 962 963 964 965 966 967
	u32  prior_delivered;	/* tp->delivered at "prior_mstamp" */
	s32  delivered;		/* number of packets delivered over interval */
	long interval_us;	/* time for tp->delivered to incr "delivered" */
	long rtt_us;		/* RTT of last (S)ACKed packet (or -1) */
	int  losses;		/* number of packets marked lost upon ACK */
	u32  acked_sacked;	/* number of packets newly (S)ACKed upon ACK */
	u32  prior_in_flight;	/* in flight before this ACK */
968
	bool is_app_limited;	/* is sample from packet with bubble in pipe? */
969 970 971
	bool is_retrans;	/* is sample from retransmission? */
};

972 973
struct tcp_congestion_ops {
	struct list_head	list;
974 975
	u32 key;
	u32 flags;
976 977

	/* initialize private data (optional) */
978
	void (*init)(struct sock *sk);
979
	/* cleanup private data  (optional) */
980
	void (*release)(struct sock *sk);
981 982

	/* return slow start threshold (required) */
983
	u32 (*ssthresh)(struct sock *sk);
984
	/* do new cwnd calculation (required) */
985
	void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
986
	/* call before changing ca_state (optional) */
987
	void (*set_state)(struct sock *sk, u8 new_state);
988
	/* call when cwnd event occurs (optional) */
989
	void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
990 991
	/* call when ack arrives (optional) */
	void (*in_ack_event)(struct sock *sk, u32 flags);
992
	/* new value of cwnd after loss (required) */
993
	u32  (*undo_cwnd)(struct sock *sk);
994
	/* hook for packet ack accounting (optional) */
995
	void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
996 997
	/* suggest number of segments for each skb to transmit (optional) */
	u32 (*tso_segs_goal)(struct sock *sk);
998 999
	/* returns the multiplier used in tcp_sndbuf_expand (optional) */
	u32 (*sndbuf_expand)(struct sock *sk);
1000 1001 1002 1003
	/* call when packets are delivered to update cwnd and pacing rate,
	 * after all the ca_state processing. (optional)
	 */
	void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
1004
	/* get info for inet_diag (optional) */
1005 1006
	size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
			   union tcp_cc_info *info);
1007 1008 1009 1010 1011

	char 		name[TCP_CA_NAME_MAX];
	struct module 	*owner;
};

1012 1013
int tcp_register_congestion_control(struct tcp_congestion_ops *type);
void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
1014

1015
void tcp_assign_congestion_control(struct sock *sk);
1016 1017 1018 1019 1020 1021 1022
void tcp_init_congestion_control(struct sock *sk);
void tcp_cleanup_congestion_control(struct sock *sk);
int tcp_set_default_congestion_control(const char *name);
void tcp_get_default_congestion_control(char *name);
void tcp_get_available_congestion_control(char *buf, size_t len);
void tcp_get_allowed_congestion_control(char *buf, size_t len);
int tcp_set_allowed_congestion_control(char *allowed);
1023
int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, bool reinit);
N
Neal Cardwell 已提交
1024 1025
u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
1026

1027
u32 tcp_reno_ssthresh(struct sock *sk);
1028
u32 tcp_reno_undo_cwnd(struct sock *sk);
1029
void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
1030
extern struct tcp_congestion_ops tcp_reno;
1031

1032
struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
1033
u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca);
1034
#ifdef CONFIG_INET
1035
char *tcp_ca_get_name_by_key(u32 key, char *buffer);
1036 1037 1038 1039 1040 1041
#else
static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
{
	return NULL;
}
#endif
1042

1043 1044 1045 1046 1047 1048 1049
static inline bool tcp_ca_needs_ecn(const struct sock *sk)
{
	const struct inet_connection_sock *icsk = inet_csk(sk);

	return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
}

1050
static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
1051
{
1052 1053 1054 1055 1056
	struct inet_connection_sock *icsk = inet_csk(sk);

	if (icsk->icsk_ca_ops->set_state)
		icsk->icsk_ca_ops->set_state(sk, ca_state);
	icsk->icsk_ca_state = ca_state;
1057 1058
}

1059
static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
1060
{
1061 1062 1063 1064
	const struct inet_connection_sock *icsk = inet_csk(sk);

	if (icsk->icsk_ca_ops->cwnd_event)
		icsk->icsk_ca_ops->cwnd_event(sk, event);
1065 1066
}

1067 1068 1069 1070 1071
/* From tcp_rate.c */
void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
			    struct rate_sample *rs);
void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1072
		  struct rate_sample *rs);
1073
void tcp_rate_check_app_limited(struct sock *sk);
1074

1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087
/* These functions determine how the current flow behaves in respect of SACK
 * handling. SACK is negotiated with the peer, and therefore it can vary
 * between different flows.
 *
 * tcp_is_sack - SACK enabled
 * tcp_is_reno - No SACK
 * tcp_is_fack - FACK enabled, implies SACK enabled
 */
static inline int tcp_is_sack(const struct tcp_sock *tp)
{
	return tp->rx_opt.sack_ok;
}

E
Eric Dumazet 已提交
1088
static inline bool tcp_is_reno(const struct tcp_sock *tp)
1089 1090 1091 1092
{
	return !tcp_is_sack(tp);
}

E
Eric Dumazet 已提交
1093
static inline bool tcp_is_fack(const struct tcp_sock *tp)
1094
{
1095
	return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
1096 1097 1098 1099
}

static inline void tcp_enable_fack(struct tcp_sock *tp)
{
1100
	tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
1101 1102
}

1103 1104 1105 1106 1107
static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
{
	return tp->sacked_out + tp->lost_out;
}

L
Linus Torvalds 已提交
1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121
/* This determines how many packets are "in the network" to the best
 * of our knowledge.  In many cases it is conservative, but where
 * detailed information is available from the receiver (via SACK
 * blocks etc.) we can make more aggressive calculations.
 *
 * Use this for decisions involving congestion control, use just
 * tp->packets_out to determine if the send queue is empty or not.
 *
 * Read this equation as:
 *
 *	"Packets sent once on transmission queue" MINUS
 *	"Packets left network, but not honestly ACKed yet" PLUS
 *	"Packets fast retransmitted"
 */
S
Stephen Hemminger 已提交
1122
static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
L
Linus Torvalds 已提交
1123
{
1124
	return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
L
Linus Torvalds 已提交
1125 1126
}

I
Ilpo Järvinen 已提交
1127 1128
#define TCP_INFINITE_SSTHRESH	0x7fffffff

1129 1130
static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
{
1131
	return tp->snd_cwnd < tp->snd_ssthresh;
1132 1133
}

I
Ilpo Järvinen 已提交
1134 1135 1136 1137 1138
static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
{
	return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
}

1139 1140 1141 1142 1143 1144
static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
{
	return (TCPF_CA_CWR | TCPF_CA_Recovery) &
	       (1 << inet_csk(sk)->icsk_ca_state);
}

L
Linus Torvalds 已提交
1145
/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1146
 * The exception is cwnd reduction phase, when cwnd is decreasing towards
L
Linus Torvalds 已提交
1147 1148
 * ssthresh.
 */
1149
static inline __u32 tcp_current_ssthresh(const struct sock *sk)
L
Linus Torvalds 已提交
1150
{
1151
	const struct tcp_sock *tp = tcp_sk(sk);
1152

1153
	if (tcp_in_cwnd_reduction(sk))
L
Linus Torvalds 已提交
1154 1155 1156 1157 1158 1159 1160
		return tp->snd_ssthresh;
	else
		return max(tp->snd_ssthresh,
			   ((tp->snd_cwnd >> 1) +
			    (tp->snd_cwnd >> 2)));
}

1161 1162
/* Use define here intentionally to get WARN_ON location shown at the caller */
#define tcp_verify_left_out(tp)	WARN_ON(tcp_left_out(tp) > tp->packets_out)
L
Linus Torvalds 已提交
1163

1164
void tcp_enter_cwr(struct sock *sk);
1165
__u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
L
Linus Torvalds 已提交
1166

1167 1168 1169 1170 1171 1172 1173 1174
/* The maximum number of MSS of available cwnd for which TSO defers
 * sending if not using sysctl_tcp_tso_win_divisor.
 */
static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
{
	return 3;
}

1175 1176 1177 1178 1179
/* Returns end sequence number of the receiver's advertised window */
static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
{
	return tp->snd_una + tp->snd_wnd;
}
1180 1181 1182

/* We follow the spirit of RFC2861 to validate cwnd but implement a more
 * flexible approach. The RFC suggests cwnd should not be raised unless
1183 1184 1185
 * it was fully used previously. And that's exactly what we do in
 * congestion avoidance mode. But in slow start we allow cwnd to grow
 * as long as the application has used half the cwnd.
1186 1187 1188 1189 1190 1191 1192 1193
 * Example :
 *    cwnd is 10 (IW10), but application sends 9 frames.
 *    We allow cwnd to reach 18 when all frames are ACKed.
 * This check is safe because it's as aggressive as slow start which already
 * risks 100% overshoot. The advantage is that we discourage application to
 * either send more filler packets or data to artificially blow up the cwnd
 * usage, and allow application-limited process to probe bw more aggressively.
 */
1194
static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1195 1196 1197
{
	const struct tcp_sock *tp = tcp_sk(sk);

1198
	/* If in slow start, ensure cwnd grows to twice what was ACKed. */
1199
	if (tcp_in_slow_start(tp))
1200 1201 1202
		return tp->snd_cwnd < 2 * tp->max_packets_out;

	return tp->is_cwnd_limited;
1203
}
1204

1205 1206 1207 1208 1209 1210 1211
/* Something is really bad, we could not queue an additional packet,
 * because qdisc is full or receiver sent a 0 window.
 * We do not want to add fuel to the fire, or abort too early,
 * so make sure the timer we arm now is at least 200ms in the future,
 * regardless of current icsk_rto value (as it could be ~2ms)
 */
static inline unsigned long tcp_probe0_base(const struct sock *sk)
L
Linus Torvalds 已提交
1212
{
1213 1214
	return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
}
1215

1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227
/* Variant of inet_csk_rto_backoff() used for zero window probes */
static inline unsigned long tcp_probe0_when(const struct sock *sk,
					    unsigned long max_when)
{
	u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff;

	return (unsigned long)min_t(u64, when, max_when);
}

static inline void tcp_check_probe_timer(struct sock *sk)
{
	if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1228
		inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1229
					  tcp_probe0_base(sk), TCP_RTO_MAX);
L
Linus Torvalds 已提交
1230 1231
}

1232
static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
L
Linus Torvalds 已提交
1233 1234 1235 1236
{
	tp->snd_wl1 = seq;
}

1237
static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
L
Linus Torvalds 已提交
1238 1239 1240 1241 1242 1243 1244
{
	tp->snd_wl1 = seq;
}

/*
 * Calculate(/check) TCP checksum
 */
1245 1246
static inline __sum16 tcp_v4_check(int len, __be32 saddr,
				   __be32 daddr, __wsum base)
L
Linus Torvalds 已提交
1247 1248 1249 1250
{
	return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
}

1251
static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
L
Linus Torvalds 已提交
1252
{
1253
	return __skb_checksum_complete(skb);
L
Linus Torvalds 已提交
1254 1255
}

E
Eric Dumazet 已提交
1256
static inline bool tcp_checksum_complete(struct sk_buff *skb)
L
Linus Torvalds 已提交
1257
{
1258
	return !skb_csum_unnecessary(skb) &&
L
Linus Torvalds 已提交
1259 1260 1261
		__tcp_checksum_complete(skb);
}

E
Eric Dumazet 已提交
1262
bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb);
1263
int tcp_filter(struct sock *sk, struct sk_buff *skb);
L
Linus Torvalds 已提交
1264 1265 1266 1267 1268 1269 1270 1271 1272 1273

#undef STATE_TRACE

#ifdef STATE_TRACE
static const char *statename[]={
	"Unused","Established","Syn Sent","Syn Recv",
	"Fin Wait 1","Fin Wait 2","Time Wait", "Close",
	"Close Wait","Last ACK","Listen","Closing"
};
#endif
1274
void tcp_set_state(struct sock *sk, int state);
L
Linus Torvalds 已提交
1275

1276
void tcp_done(struct sock *sk);
L
Linus Torvalds 已提交
1277

1278 1279
int tcp_abort(struct sock *sk, int err);

S
Stephen Hemminger 已提交
1280
static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
L
Linus Torvalds 已提交
1281 1282 1283 1284 1285
{
	rx_opt->dsack = 0;
	rx_opt->num_sacks = 0;
}

1286
u32 tcp_default_init_rwnd(u32 mss);
1287 1288 1289 1290
void tcp_cwnd_restart(struct sock *sk, s32 delta);

static inline void tcp_slow_start_after_idle_check(struct sock *sk)
{
1291
	const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
1292 1293 1294
	struct tcp_sock *tp = tcp_sk(sk);
	s32 delta;

1295
	if (!sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle || tp->packets_out ||
1296
	    ca_ops->cong_control)
1297
		return;
1298
	delta = tcp_jiffies32 - tp->lsndtime;
1299 1300 1301
	if (delta > inet_csk(sk)->icsk_rto)
		tcp_cwnd_restart(sk, delta);
}
1302

L
Linus Torvalds 已提交
1303
/* Determine a window scaling and initial window to offer. */
1304 1305
void tcp_select_initial_window(const struct sock *sk, int __space,
			       __u32 mss, __u32 *rcv_wnd,
1306 1307
			       __u32 *window_clamp, int wscale_ok,
			       __u8 *rcv_wscale, __u32 init_rcv_wnd);
L
Linus Torvalds 已提交
1308

1309
static inline int tcp_win_from_space(const struct sock *sk, int space)
L
Linus Torvalds 已提交
1310
{
1311
	int tcp_adv_win_scale = sock_net(sk)->ipv4.sysctl_tcp_adv_win_scale;
1312 1313 1314 1315

	return tcp_adv_win_scale <= 0 ?
		(space>>(-tcp_adv_win_scale)) :
		space - (space>>tcp_adv_win_scale);
L
Linus Torvalds 已提交
1316 1317
}

1318
/* Note: caller must be prepared to deal with negative returns */
L
Linus Torvalds 已提交
1319 1320
static inline int tcp_space(const struct sock *sk)
{
1321
	return tcp_win_from_space(sk, sk->sk_rcvbuf -
L
Linus Torvalds 已提交
1322
				  atomic_read(&sk->sk_rmem_alloc));
1323
}
L
Linus Torvalds 已提交
1324 1325 1326

static inline int tcp_full_space(const struct sock *sk)
{
1327
	return tcp_win_from_space(sk, sk->sk_rcvbuf);
L
Linus Torvalds 已提交
1328 1329
}

1330
extern void tcp_openreq_init_rwin(struct request_sock *req,
1331 1332
				  const struct sock *sk_listener,
				  const struct dst_entry *dst);
1333

1334
void tcp_enter_memory_pressure(struct sock *sk);
1335
void tcp_leave_memory_pressure(struct sock *sk);
L
Linus Torvalds 已提交
1336 1337 1338

static inline int keepalive_intvl_when(const struct tcp_sock *tp)
{
1339 1340 1341
	struct net *net = sock_net((struct sock *)tp);

	return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl;
L
Linus Torvalds 已提交
1342 1343 1344 1345
}

static inline int keepalive_time_when(const struct tcp_sock *tp)
{
1346 1347 1348
	struct net *net = sock_net((struct sock *)tp);

	return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time;
L
Linus Torvalds 已提交
1349 1350
}

E
Eric Dumazet 已提交
1351 1352
static inline int keepalive_probes(const struct tcp_sock *tp)
{
1353 1354 1355
	struct net *net = sock_net((struct sock *)tp);

	return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes;
E
Eric Dumazet 已提交
1356 1357
}

1358 1359 1360 1361
static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
{
	const struct inet_connection_sock *icsk = &tp->inet_conn;

1362 1363
	return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime,
			  tcp_jiffies32 - tp->rcv_tstamp);
1364 1365
}

1366
static inline int tcp_fin_time(const struct sock *sk)
L
Linus Torvalds 已提交
1367
{
1368
	int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout;
1369
	const int rto = inet_csk(sk)->icsk_rto;
L
Linus Torvalds 已提交
1370

1371 1372
	if (fin_timeout < (rto << 2) - (rto >> 1))
		fin_timeout = (rto << 2) - (rto >> 1);
L
Linus Torvalds 已提交
1373 1374 1375 1376

	return fin_timeout;
}

E
Eric Dumazet 已提交
1377 1378
static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
				  int paws_win)
L
Linus Torvalds 已提交
1379
{
I
Ilpo Järvinen 已提交
1380
	if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
E
Eric Dumazet 已提交
1381
		return true;
I
Ilpo Järvinen 已提交
1382
	if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
E
Eric Dumazet 已提交
1383
		return true;
E
Eric Dumazet 已提交
1384 1385 1386 1387 1388 1389
	/*
	 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
	 * then following tcp messages have valid values. Ignore 0 value,
	 * or else 'negative' tsval might forbid us to accept their packets.
	 */
	if (!rx_opt->ts_recent)
E
Eric Dumazet 已提交
1390 1391
		return true;
	return false;
I
Ilpo Järvinen 已提交
1392 1393
}

E
Eric Dumazet 已提交
1394 1395
static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
				   int rst)
I
Ilpo Järvinen 已提交
1396 1397
{
	if (tcp_paws_check(rx_opt, 0))
E
Eric Dumazet 已提交
1398
		return false;
L
Linus Torvalds 已提交
1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411

	/* RST segments are not recommended to carry timestamp,
	   and, if they do, it is recommended to ignore PAWS because
	   "their cleanup function should take precedence over timestamps."
	   Certainly, it is mistake. It is necessary to understand the reasons
	   of this constraint to relax it: if peer reboots, clock may go
	   out-of-sync and half-open connections will not be reset.
	   Actually, the problem would be not existing if all
	   the implementations followed draft about maintaining clock
	   via reboots. Linux-2.2 DOES NOT!

	   However, we can relax time bounds for RST segments to MSL.
	 */
1412
	if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
E
Eric Dumazet 已提交
1413 1414
		return false;
	return true;
L
Linus Torvalds 已提交
1415 1416
}

1417 1418
bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
			  int mib_idx, u32 *last_oow_ack_time);
1419

P
Pavel Emelyanov 已提交
1420
static inline void tcp_mib_init(struct net *net)
L
Linus Torvalds 已提交
1421 1422
{
	/* See RFC 2012 */
1423 1424 1425 1426
	TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
	TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
	TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
	TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
L
Linus Torvalds 已提交
1427 1428
}

1429
/* from STCP */
1430
static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
D
David S. Miller 已提交
1431
{
1432
	tp->lost_skb_hint = NULL;
1433 1434 1435 1436 1437
}

static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
{
	tcp_clear_retrans_hints_partial(tp);
1438
	tp->retransmit_skb_hint = NULL;
1439 1440
}

E
Eric Dumazet 已提交
1441 1442 1443 1444 1445 1446 1447
union tcp_md5_addr {
	struct in_addr  a4;
#if IS_ENABLED(CONFIG_IPV6)
	struct in6_addr	a6;
#endif
};

1448 1449
/* - key database */
struct tcp_md5sig_key {
E
Eric Dumazet 已提交
1450
	struct hlist_node	node;
1451
	u8			keylen;
E
Eric Dumazet 已提交
1452 1453
	u8			family; /* AF_INET or AF_INET6 */
	union tcp_md5_addr	addr;
1454
	u8			prefixlen;
E
Eric Dumazet 已提交
1455 1456
	u8			key[TCP_MD5SIG_MAXKEYLEN];
	struct rcu_head		rcu;
1457 1458 1459 1460
};

/* - sock block */
struct tcp_md5sig_info {
E
Eric Dumazet 已提交
1461
	struct hlist_head	head;
1462
	struct rcu_head		rcu;
1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482
};

/* - pseudo header */
struct tcp4_pseudohdr {
	__be32		saddr;
	__be32		daddr;
	__u8		pad;
	__u8		protocol;
	__be16		len;
};

struct tcp6_pseudohdr {
	struct in6_addr	saddr;
	struct in6_addr daddr;
	__be32		len;
	__be32		protocol;	/* including padding */
};

union tcp_md5sum_block {
	struct tcp4_pseudohdr ip4;
E
Eric Dumazet 已提交
1483
#if IS_ENABLED(CONFIG_IPV6)
1484 1485 1486 1487 1488 1489
	struct tcp6_pseudohdr ip6;
#endif
};

/* - pool: digest algorithm, hash description and scratch buffer */
struct tcp_md5sig_pool {
H
Herbert Xu 已提交
1490
	struct ahash_request	*md5_req;
1491
	void			*scratch;
1492 1493 1494
};

/* - functions */
1495 1496
int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
			const struct sock *sk, const struct sk_buff *skb);
1497
int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1498 1499
		   int family, u8 prefixlen, const u8 *newkey, u8 newkeylen,
		   gfp_t gfp);
1500
int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1501
		   int family, u8 prefixlen);
1502
struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1503
					 const struct sock *addr_sk);
1504

1505
#ifdef CONFIG_TCP_MD5SIG
1506
struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1507 1508
					 const union tcp_md5_addr *addr,
					 int family);
E
Eric Dumazet 已提交
1509
#define tcp_twsk_md5_key(twsk)	((twsk)->tw_md5_key)
1510
#else
1511
static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
E
Eric Dumazet 已提交
1512 1513 1514 1515 1516
					 const union tcp_md5_addr *addr,
					 int family)
{
	return NULL;
}
1517 1518 1519
#define tcp_twsk_md5_key(twsk)	NULL
#endif

1520
bool tcp_alloc_md5sig_pool(void);
1521

1522
struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1523 1524 1525 1526
static inline void tcp_put_md5sig_pool(void)
{
	local_bh_enable();
}
E
Eric Dumazet 已提交
1527

1528 1529 1530 1531
int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
			  unsigned int header_len);
int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
		     const struct tcp_md5sig_key *key);
1532

1533
/* From tcp_fastopen.c */
1534 1535 1536 1537
void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
			    struct tcp_fastopen_cookie *cookie, int *syn_loss,
			    unsigned long *last_syn_loss);
void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1538 1539
			    struct tcp_fastopen_cookie *cookie, bool syn_lost,
			    u16 try_exp);
1540 1541 1542 1543
struct tcp_fastopen_request {
	/* Fast Open cookie. Size 0 means a cookie request */
	struct tcp_fastopen_cookie	cookie;
	struct msghdr			*data;  /* data in MSG_FASTOPEN */
1544 1545
	size_t				size;
	int				copied;	/* queued in tcp_connect() */
1546 1547
};
void tcp_free_fastopen_req(struct tcp_sock *tp);
1548
void tcp_fastopen_destroy_cipher(struct sock *sk);
1549
void tcp_fastopen_ctx_destroy(struct net *net);
1550 1551
int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
			      void *key, unsigned int len);
1552
void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1553 1554
struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
			      struct request_sock *req,
1555 1556
			      struct tcp_fastopen_cookie *foc,
			      const struct dst_entry *dst);
1557
void tcp_fastopen_init_key_once(struct net *net);
1558 1559
bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
			     struct tcp_fastopen_cookie *cookie);
W
Wei Wang 已提交
1560
bool tcp_fastopen_defer_connect(struct sock *sk, int *err);
1561 1562 1563 1564
#define TCP_FASTOPEN_KEY_LENGTH 16

/* Fastopen key context */
struct tcp_fastopen_context {
1565 1566 1567
	struct crypto_cipher	*tfm;
	__u8			key[TCP_FASTOPEN_KEY_LENGTH];
	struct rcu_head		rcu;
1568 1569
};

1570
extern unsigned int sysctl_tcp_fastopen_blackhole_timeout;
1571
void tcp_fastopen_active_disable(struct sock *sk);
1572 1573 1574 1575
bool tcp_fastopen_active_should_disable(struct sock *sk);
void tcp_fastopen_active_disable_ofo_check(struct sock *sk);
void tcp_fastopen_active_timeout_reset(void);

1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589
/* Latencies incurred by various limits for a sender. They are
 * chronograph-like stats that are mutually exclusive.
 */
enum tcp_chrono {
	TCP_CHRONO_UNSPEC,
	TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
	TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
	TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
	__TCP_CHRONO_MAX,
};

void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);

1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606
/* This helper is needed, because skb->tcp_tsorted_anchor uses
 * the same memory storage than skb->destructor/_skb_refdst
 */
static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb)
{
	skb->destructor = NULL;
	skb->_skb_refdst = 0UL;
}

#define tcp_skb_tsorted_save(skb) {		\
	unsigned long _save = skb->_skb_refdst;	\
	skb->_skb_refdst = 0UL;

#define tcp_skb_tsorted_restore(skb)		\
	skb->_skb_refdst = _save;		\
}

1607
void tcp_write_queue_purge(struct sock *sk);
1608

1609 1610 1611 1612 1613
static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk)
{
	return skb_rb_first(&sk->tcp_rtx_queue);
}

1614
static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1615
{
1616
	return skb_peek(&sk->sk_write_queue);
1617 1618
}

1619
static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1620
{
1621
	return skb_peek_tail(&sk->sk_write_queue);
1622 1623
}

1624
#define tcp_for_write_queue_from_safe(skb, tmp, sk)			\
1625
	skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1626

1627
static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1628
{
1629
	return skb_peek(&sk->sk_write_queue);
1630 1631
}

1632 1633 1634 1635 1636 1637
static inline bool tcp_skb_is_last(const struct sock *sk,
				   const struct sk_buff *skb)
{
	return skb_queue_is_last(&sk->sk_write_queue, skb);
}

1638
static inline bool tcp_write_queue_empty(const struct sock *sk)
1639
{
1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650
	return skb_queue_empty(&sk->sk_write_queue);
}

static inline bool tcp_rtx_queue_empty(const struct sock *sk)
{
	return RB_EMPTY_ROOT(&sk->tcp_rtx_queue);
}

static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk)
{
	return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk);
1651 1652 1653 1654
}

static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
{
1655
	if (tcp_write_queue_empty(sk))
1656
		tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
1657

1658 1659
	if (tcp_sk(sk)->highest_sack == skb_unlinked)
		tcp_sk(sk)->highest_sack = NULL;
1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671
}

static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
{
	__skb_queue_tail(&sk->sk_write_queue, skb);
}

static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
{
	__tcp_add_write_queue_tail(sk, skb);

	/* Queue it, remembering where we must start sending. */
1672
	if (sk->sk_write_queue.next == skb) {
1673
		tcp_chrono_start(sk, TCP_CHRONO_BUSY);
1674 1675 1676 1677

		if (tcp_sk(sk)->highest_sack == NULL)
			tcp_sk(sk)->highest_sack = skb;
	}
1678 1679
}

1680
/* Insert new before skb on the write queue of sk.  */
1681 1682 1683 1684
static inline void tcp_insert_write_queue_before(struct sk_buff *new,
						  struct sk_buff *skb,
						  struct sock *sk)
{
1685
	__skb_queue_before(&sk->sk_write_queue, skb, new);
1686 1687 1688 1689
}

static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
{
E
Eric Dumazet 已提交
1690
	tcp_skb_tsorted_anchor_cleanup(skb);
1691 1692 1693
	__skb_unlink(skb, &sk->sk_write_queue);
}

1694 1695 1696
void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb);

static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk)
1697
{
1698 1699 1700 1701 1702 1703 1704 1705 1706
	tcp_skb_tsorted_anchor_cleanup(skb);
	rb_erase(&skb->rbnode, &sk->tcp_rtx_queue);
}

static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk)
{
	list_del(&skb->tcp_tsorted_anchor);
	tcp_rtx_queue_unlink(skb, sk);
	sk_wmem_free_skb(sk, skb);
1707 1708
}

1709 1710 1711 1712 1713 1714 1715 1716 1717
static inline void tcp_push_pending_frames(struct sock *sk)
{
	if (tcp_send_head(sk)) {
		struct tcp_sock *tp = tcp_sk(sk);

		__tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
	}
}

1718 1719 1720
/* Start sequence of the skb just after the highest skb with SACKed
 * bit, valid only if sacked_out > 0 or when the caller has ensured
 * validity by itself.
1721 1722 1723 1724 1725
 */
static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
{
	if (!tp->sacked_out)
		return tp->snd_una;
1726 1727 1728 1729

	if (tp->highest_sack == NULL)
		return tp->snd_nxt;

1730 1731 1732
	return TCP_SKB_CB(tp->highest_sack)->seq;
}

1733 1734
static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
{
1735 1736 1737
	struct sk_buff *next = skb_rb_next(skb);

	tcp_sk(sk)->highest_sack = next ?: tcp_send_head(sk);
1738 1739 1740 1741 1742 1743 1744 1745 1746
}

static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
{
	return tcp_sk(sk)->highest_sack;
}

static inline void tcp_highest_sack_reset(struct sock *sk)
{
1747 1748 1749
	struct sk_buff *skb = tcp_rtx_queue_head(sk);

	tcp_sk(sk)->highest_sack = skb ?: tcp_send_head(sk);
1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760
}

/* Called when old skb is about to be deleted (to be combined with new skb) */
static inline void tcp_highest_sack_combine(struct sock *sk,
					    struct sk_buff *old,
					    struct sk_buff *new)
{
	if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
		tcp_sk(sk)->highest_sack = new;
}

1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772
/* This helper checks if socket has IP_TRANSPARENT set */
static inline bool inet_sk_transparent(const struct sock *sk)
{
	switch (sk->sk_state) {
	case TCP_TIME_WAIT:
		return inet_twsk(sk)->tw_transparent;
	case TCP_NEW_SYN_RECV:
		return inet_rsk(inet_reqsk(sk))->no_srccheck;
	}
	return inet_sk(sk)->transparent;
}

A
Andreas Petlund 已提交
1773 1774 1775
/* Determines whether this is a thin stream (which may suffer from
 * increased latency). Used to trigger latency-reducing mechanisms.
 */
E
Eric Dumazet 已提交
1776
static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
A
Andreas Petlund 已提交
1777 1778 1779 1780
{
	return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
}

L
Linus Torvalds 已提交
1781 1782 1783 1784 1785 1786
/* /proc */
enum tcp_seq_states {
	TCP_SEQ_STATE_LISTENING,
	TCP_SEQ_STATE_ESTABLISHED,
};

1787 1788
int tcp_seq_open(struct inode *inode, struct file *file);

L
Linus Torvalds 已提交
1789
struct tcp_seq_afinfo {
1790 1791 1792 1793
	char				*name;
	sa_family_t			family;
	const struct file_operations	*seq_fops;
	struct seq_operations		seq_ops;
L
Linus Torvalds 已提交
1794 1795 1796
};

struct tcp_iter_state {
1797
	struct seq_net_private	p;
L
Linus Torvalds 已提交
1798 1799 1800
	sa_family_t		family;
	enum tcp_seq_states	state;
	struct sock		*syn_wait_sk;
1801
	int			bucket, offset, sbucket, num;
1802
	loff_t			last_pos;
L
Linus Torvalds 已提交
1803 1804
};

1805 1806
int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
L
Linus Torvalds 已提交
1807

1808
extern struct request_sock_ops tcp_request_sock_ops;
1809
extern struct request_sock_ops tcp6_request_sock_ops;
1810

1811
void tcp_v4_destroy_sock(struct sock *sk);
1812

E
Eric Dumazet 已提交
1813
struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
1814 1815 1816
				netdev_features_t features);
struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb);
int tcp_gro_complete(struct sk_buff *skb);
1817

1818
void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
H
Herbert Xu 已提交
1819

1820 1821
static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
{
1822 1823
	struct net *net = sock_net((struct sock *)tp);
	return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat;
1824 1825 1826 1827 1828 1829 1830 1831 1832 1833
}

static inline bool tcp_stream_memory_free(const struct sock *sk)
{
	const struct tcp_sock *tp = tcp_sk(sk);
	u32 notsent_bytes = tp->write_seq - tp->snd_nxt;

	return notsent_bytes < tcp_notsent_lowat(tp);
}

1834
#ifdef CONFIG_PROC_FS
1835 1836
int tcp4_proc_init(void);
void tcp4_proc_exit(void);
1837 1838
#endif

1839
int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
O
Octavian Purdila 已提交
1840 1841 1842
int tcp_conn_request(struct request_sock_ops *rsk_ops,
		     const struct tcp_request_sock_ops *af_ops,
		     struct sock *sk, struct sk_buff *skb);
1843

1844 1845 1846
/* TCP af-specific functions */
struct tcp_sock_af_ops {
#ifdef CONFIG_TCP_MD5SIG
1847
	struct tcp_md5sig_key	*(*md5_lookup) (const struct sock *sk,
1848
						const struct sock *addr_sk);
1849 1850 1851 1852 1853
	int		(*calc_md5_hash)(char *location,
					 const struct tcp_md5sig_key *md5,
					 const struct sock *sk,
					 const struct sk_buff *skb);
	int		(*md5_parse)(struct sock *sk,
1854
				     int optname,
1855 1856
				     char __user *optval,
				     int optlen);
1857 1858 1859 1860
#endif
};

struct tcp_request_sock_ops {
1861
	u16 mss_clamp;
1862
#ifdef CONFIG_TCP_MD5SIG
1863
	struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
1864
						 const struct sock *addr_sk);
1865 1866 1867 1868
	int		(*calc_md5_hash) (char *location,
					  const struct tcp_md5sig_key *md5,
					  const struct sock *sk,
					  const struct sk_buff *skb);
1869
#endif
1870 1871
	void (*init_req)(struct request_sock *req,
			 const struct sock *sk_listener,
1872
			 struct sk_buff *skb);
1873
#ifdef CONFIG_SYN_COOKIES
1874
	__u32 (*cookie_init_seq)(const struct sk_buff *skb,
1875 1876
				 __u16 *mss);
#endif
1877
	struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl,
1878
				       const struct request_sock *req);
1879
	u32 (*init_seq)(const struct sk_buff *skb);
1880
	u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb);
1881
	int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
1882
			   struct flowi *fl, struct request_sock *req,
1883
			   struct tcp_fastopen_cookie *foc,
1884
			   enum tcp_synack_type synack_type);
1885 1886
};

1887 1888
#ifdef CONFIG_SYN_COOKIES
static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1889
					 const struct sock *sk, struct sk_buff *skb,
1890 1891
					 __u16 *mss)
{
1892
	tcp_synq_overflow(sk);
1893
	__NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
1894
	return ops->cookie_init_seq(skb, mss);
1895 1896 1897
}
#else
static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1898
					 const struct sock *sk, struct sk_buff *skb,
1899 1900 1901 1902 1903 1904
					 __u16 *mss)
{
	return 0;
}
#endif

1905
int tcpv4_offload_init(void);
1906

1907 1908
void tcp_v4_init(void);
void tcp_init(void);
1909

1910
/* tcp_recovery.c */
1911
extern void tcp_rack_mark_lost(struct sock *sk);
1912
extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
1913
			     u64 xmit_time);
1914
extern void tcp_rack_reo_timeout(struct sock *sk);
1915

1916 1917 1918
/* At how many usecs into the future should the RTO fire? */
static inline s64 tcp_rto_delta_us(const struct sock *sk)
{
1919
	const struct sk_buff *skb = tcp_rtx_queue_head(sk);
1920 1921 1922 1923 1924 1925
	u32 rto = inet_csk(sk)->icsk_rto;
	u64 rto_time_stamp_us = skb->skb_mstamp + jiffies_to_usecs(rto);

	return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp;
}

1926 1927 1928
/*
 * Save and compile IPv4 options, return a pointer to it
 */
1929 1930
static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net,
							 struct sk_buff *skb)
1931 1932 1933 1934
{
	const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
	struct ip_options_rcu *dopt = NULL;

C
Cong Wang 已提交
1935
	if (opt->optlen) {
1936 1937 1938
		int opt_size = sizeof(*dopt) + opt->optlen;

		dopt = kmalloc(opt_size, GFP_ATOMIC);
1939
		if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) {
1940 1941 1942 1943 1944 1945 1946
			kfree(dopt);
			dopt = NULL;
		}
	}
	return dopt;
}

E
Eric Dumazet 已提交
1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961
/* locally generated TCP pure ACKs have skb->truesize == 2
 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
 * This is much faster than dissecting the packet to find out.
 * (Think of GRE encapsulations, IPv4, IPv6, ...)
 */
static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
{
	return skb->truesize == 2;
}

static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
{
	skb->truesize = 2;
}

1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985
static inline int tcp_inq(struct sock *sk)
{
	struct tcp_sock *tp = tcp_sk(sk);
	int answ;

	if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
		answ = 0;
	} else if (sock_flag(sk, SOCK_URGINLINE) ||
		   !tp->urg_data ||
		   before(tp->urg_seq, tp->copied_seq) ||
		   !before(tp->urg_seq, tp->rcv_nxt)) {

		answ = tp->rcv_nxt - tp->copied_seq;

		/* Subtract 1, if FIN was received */
		if (answ && sock_flag(sk, SOCK_DONE))
			answ--;
	} else {
		answ = tp->urg_seq - tp->copied_seq;
	}

	return answ;
}

1986 1987
int tcp_peek_len(struct socket *sock);

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997
static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
{
	u16 segs_in;

	segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
	tp->segs_in += segs_in;
	if (skb->len > tcp_hdrlen(skb))
		tp->data_segs_in += segs_in;
}

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
/*
 * TCP listen path runs lockless.
 * We forced "struct sock" to be const qualified to make sure
 * we don't modify one of its field by mistake.
 * Here, we increment sk_drops which is an atomic_t, so we can safely
 * make sock writable again.
 */
static inline void tcp_listendrop(const struct sock *sk)
{
	atomic_inc(&((struct sock *)sk)->sk_drops);
2008
	__NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
2009 2010
}

2011 2012
enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);

D
Dave Watson 已提交
2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037
/*
 * Interface for adding Upper Level Protocols over TCP
 */

#define TCP_ULP_NAME_MAX	16
#define TCP_ULP_MAX		128
#define TCP_ULP_BUF_MAX		(TCP_ULP_NAME_MAX*TCP_ULP_MAX)

struct tcp_ulp_ops {
	struct list_head	list;

	/* initialize ulp */
	int (*init)(struct sock *sk);
	/* cleanup ulp */
	void (*release)(struct sock *sk);

	char		name[TCP_ULP_NAME_MAX];
	struct module	*owner;
};
int tcp_register_ulp(struct tcp_ulp_ops *type);
void tcp_unregister_ulp(struct tcp_ulp_ops *type);
int tcp_set_ulp(struct sock *sk, const char *name);
void tcp_get_available_ulp(char *buf, size_t len);
void tcp_cleanup_ulp(struct sock *sk);

L
Lawrence Brakmo 已提交
2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069
/* Call BPF_SOCK_OPS program that returns an int. If the return value
 * is < 0, then the BPF op failed (for example if the loaded BPF
 * program does not support the chosen operation or there is no BPF
 * program loaded).
 */
#ifdef CONFIG_BPF
static inline int tcp_call_bpf(struct sock *sk, int op)
{
	struct bpf_sock_ops_kern sock_ops;
	int ret;

	if (sk_fullsock(sk))
		sock_owned_by_me(sk);

	memset(&sock_ops, 0, sizeof(sock_ops));
	sock_ops.sk = sk;
	sock_ops.op = op;

	ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops);
	if (ret == 0)
		ret = sock_ops.reply;
	else
		ret = -1;
	return ret;
}
#else
static inline int tcp_call_bpf(struct sock *sk, int op)
{
	return -EPERM;
}
#endif

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static inline u32 tcp_timeout_init(struct sock *sk)
{
	int timeout;

	timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT);

	if (timeout <= 0)
		timeout = TCP_TIMEOUT_INIT;
	return timeout;
}

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static inline u32 tcp_rwnd_init_bpf(struct sock *sk)
{
	int rwnd;

	rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT);

	if (rwnd < 0)
		rwnd = 0;
	return rwnd;
}
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static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)
{
	return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN) == 1);
}
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#if IS_ENABLED(CONFIG_SMC)
extern struct static_key_false tcp_have_smc;
#endif
L
Linus Torvalds 已提交
2100
#endif	/* _TCP_H */