Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 4864 insertions, 0 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
new file mode 100644
index 000000000..90e24c3f6
--- /dev/null
+++ b/net/ipv4/tcp.c
@@ -0,0 +1,4864 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * 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.
+ *
+ *		Implementation of the Transmission Control Protocol(TCP).
+ *
+ * Authors:	Ross Biro
+ *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
+ *		Mark Evans, <evansmp@uhura.aston.ac.uk>
+ *		Corey Minyard <wf-rch!minyard@relay.EU.net>
+ *		Florian La Roche, <flla@stud.uni-sb.de>
+ *		Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
+ *		Linus Torvalds, <torvalds@cs.helsinki.fi>
+ *		Alan Cox, <gw4pts@gw4pts.ampr.org>
+ *		Matthew Dillon, <dillon@apollo.west.oic.com>
+ *		Arnt Gulbrandsen, <agulbra@nvg.unit.no>
+ *		Jorge Cwik, <jorge@laser.satlink.net>
+ *
+ * Fixes:
+ *		Alan Cox	:	Numerous verify_area() calls
+ *		Alan Cox	:	Set the ACK bit on a reset
+ *		Alan Cox	:	Stopped it crashing if it closed while
+ *					sk->inuse=1 and was trying to connect
+ *					(tcp_err()).
+ *		Alan Cox	:	All icmp error handling was broken
+ *					pointers passed where wrong and the
+ *					socket was looked up backwards. Nobody
+ *					tested any icmp error code obviously.
+ *		Alan Cox	:	tcp_err() now handled properly. It
+ *					wakes people on errors. poll
+ *					behaves and the icmp error race
+ *					has gone by moving it into sock.c
+ *		Alan Cox	:	tcp_send_reset() fixed to work for
+ *					everything not just packets for
+ *					unknown sockets.
+ *		Alan Cox	:	tcp option processing.
+ *		Alan Cox	:	Reset tweaked (still not 100%) [Had
+ *					syn rule wrong]
+ *		Herp Rosmanith  :	More reset fixes
+ *		Alan Cox	:	No longer acks invalid rst frames.
+ *					Acking any kind of RST is right out.
+ *		Alan Cox	:	Sets an ignore me flag on an rst
+ *					receive otherwise odd bits of prattle
+ *					escape still
+ *		Alan Cox	:	Fixed another acking RST frame bug.
+ *					Should stop LAN workplace lockups.
+ *		Alan Cox	: 	Some tidyups using the new skb list
+ *					facilities
+ *		Alan Cox	:	sk->keepopen now seems to work
+ *		Alan Cox	:	Pulls options out correctly on accepts
+ *		Alan Cox	:	Fixed assorted sk->rqueue->next errors
+ *		Alan Cox	:	PSH doesn't end a TCP read. Switched a
+ *					bit to skb ops.
+ *		Alan Cox	:	Tidied tcp_data to avoid a potential
+ *					nasty.
+ *		Alan Cox	:	Added some better commenting, as the
+ *					tcp is hard to follow
+ *		Alan Cox	:	Removed incorrect check for 20 * psh
+ *	Michael O'Reilly	:	ack < copied bug fix.
+ *	Johannes Stille		:	Misc tcp fixes (not all in yet).
+ *		Alan Cox	:	FIN with no memory -> CRASH
+ *		Alan Cox	:	Added socket option proto entries.
+ *					Also added awareness of them to accept.
+ *		Alan Cox	:	Added TCP options (SOL_TCP)
+ *		Alan Cox	:	Switched wakeup calls to callbacks,
+ *					so the kernel can layer network
+ *					sockets.
+ *		Alan Cox	:	Use ip_tos/ip_ttl settings.
+ *		Alan Cox	:	Handle FIN (more) properly (we hope).
+ *		Alan Cox	:	RST frames sent on unsynchronised
+ *					state ack error.
+ *		Alan Cox	:	Put in missing check for SYN bit.
+ *		Alan Cox	:	Added tcp_select_window() aka NET2E
+ *					window non shrink trick.
+ *		Alan Cox	:	Added a couple of small NET2E timer
+ *					fixes
+ *		Charles Hedrick :	TCP fixes
+ *		Toomas Tamm	:	TCP window fixes
+ *		Alan Cox	:	Small URG fix to rlogin ^C ack fight
+ *		Charles Hedrick	:	Rewrote most of it to actually work
+ *		Linus		:	Rewrote tcp_read() and URG handling
+ *					completely
+ *		Gerhard Koerting:	Fixed some missing timer handling
+ *		Matthew Dillon  :	Reworked TCP machine states as per RFC
+ *		Gerhard Koerting:	PC/TCP workarounds
+ *		Adam Caldwell	:	Assorted timer/timing errors
+ *		Matthew Dillon	:	Fixed another RST bug
+ *		Alan Cox	:	Move to kernel side addressing changes.
+ *		Alan Cox	:	Beginning work on TCP fastpathing
+ *					(not yet usable)
+ *		Arnt Gulbrandsen:	Turbocharged tcp_check() routine.
+ *		Alan Cox	:	TCP fast path debugging
+ *		Alan Cox	:	Window clamping
+ *		Michael Riepe	:	Bug in tcp_check()
+ *		Matt Dillon	:	More TCP improvements and RST bug fixes
+ *		Matt Dillon	:	Yet more small nasties remove from the
+ *					TCP code (Be very nice to this man if
+ *					tcp finally works 100%) 8)
+ *		Alan Cox	:	BSD accept semantics.
+ *		Alan Cox	:	Reset on closedown bug.
+ *	Peter De Schrijver	:	ENOTCONN check missing in tcp_sendto().
+ *		Michael Pall	:	Handle poll() after URG properly in
+ *					all cases.
+ *		Michael Pall	:	Undo the last fix in tcp_read_urg()
+ *					(multi URG PUSH broke rlogin).
+ *		Michael Pall	:	Fix the multi URG PUSH problem in
+ *					tcp_readable(), poll() after URG
+ *					works now.
+ *		Michael Pall	:	recv(...,MSG_OOB) never blocks in the
+ *					BSD api.
+ *		Alan Cox	:	Changed the semantics of sk->socket to
+ *					fix a race and a signal problem with
+ *					accept() and async I/O.
+ *		Alan Cox	:	Relaxed the rules on tcp_sendto().
+ *		Yury Shevchuk	:	Really fixed accept() blocking problem.
+ *		Craig I. Hagan  :	Allow for BSD compatible TIME_WAIT for
+ *					clients/servers which listen in on
+ *					fixed ports.
+ *		Alan Cox	:	Cleaned the above up and shrank it to
+ *					a sensible code size.
+ *		Alan Cox	:	Self connect lockup fix.
+ *		Alan Cox	:	No connect to multicast.
+ *		Ross Biro	:	Close unaccepted children on master
+ *					socket close.
+ *		Alan Cox	:	Reset tracing code.
+ *		Alan Cox	:	Spurious resets on shutdown.
+ *		Alan Cox	:	Giant 15 minute/60 second timer error
+ *		Alan Cox	:	Small whoops in polling before an
+ *					accept.
+ *		Alan Cox	:	Kept the state trace facility since
+ *					it's handy for debugging.
+ *		Alan Cox	:	More reset handler fixes.
+ *		Alan Cox	:	Started rewriting the code based on
+ *					the RFC's for other useful protocol
+ *					references see: Comer, KA9Q NOS, and
+ *					for a reference on the difference
+ *					between specifications and how BSD
+ *					works see the 4.4lite source.
+ *		A.N.Kuznetsov	:	Don't time wait on completion of tidy
+ *					close.
+ *		Linus Torvalds	:	Fin/Shutdown & copied_seq changes.
+ *		Linus Torvalds	:	Fixed BSD port reuse to work first syn
+ *		Alan Cox	:	Reimplemented timers as per the RFC
+ *					and using multiple timers for sanity.
+ *		Alan Cox	:	Small bug fixes, and a lot of new
+ *					comments.
+ *		Alan Cox	:	Fixed dual reader crash by locking
+ *					the buffers (much like datagram.c)
+ *		Alan Cox	:	Fixed stuck sockets in probe. A probe
+ *					now gets fed up of retrying without
+ *					(even a no space) answer.
+ *		Alan Cox	:	Extracted closing code better
+ *		Alan Cox	:	Fixed the closing state machine to
+ *					resemble the RFC.
+ *		Alan Cox	:	More 'per spec' fixes.
+ *		Jorge Cwik	:	Even faster checksumming.
+ *		Alan Cox	:	tcp_data() doesn't ack illegal PSH
+ *					only frames. At least one pc tcp stack
+ *					generates them.
+ *		Alan Cox	:	Cache last socket.
+ *		Alan Cox	:	Per route irtt.
+ *		Matt Day	:	poll()->select() match BSD precisely on error
+ *		Alan Cox	:	New buffers
+ *		Marc Tamsky	:	Various sk->prot->retransmits and
+ *					sk->retransmits misupdating fixed.
+ *					Fixed tcp_write_timeout: stuck close,
+ *					and TCP syn retries gets used now.
+ *		Mark Yarvis	:	In tcp_read_wakeup(), don't send an
+ *					ack if state is TCP_CLOSED.
+ *		Alan Cox	:	Look up device on a retransmit - routes may
+ *					change. Doesn't yet cope with MSS shrink right
+ *					but it's a start!
+ *		Marc Tamsky	:	Closing in closing fixes.
+ *		Mike Shaver	:	RFC1122 verifications.
+ *		Alan Cox	:	rcv_saddr errors.
+ *		Alan Cox	:	Block double connect().
+ *		Alan Cox	:	Small hooks for enSKIP.
+ *		Alexey Kuznetsov:	Path MTU discovery.
+ *		Alan Cox	:	Support soft errors.
+ *		Alan Cox	:	Fix MTU discovery pathological case
+ *					when the remote claims no mtu!
+ *		Marc Tamsky	:	TCP_CLOSE fix.
+ *		Colin (G3TNE)	:	Send a reset on syn ack replies in
+ *					window but wrong (fixes NT lpd problems)
+ *		Pedro Roque	:	Better TCP window handling, delayed ack.
+ *		Joerg Reuter	:	No modification of locked buffers in
+ *					tcp_do_retransmit()
+ *		Eric Schenk	:	Changed receiver side silly window
+ *					avoidance algorithm to BSD style
+ *					algorithm. This doubles throughput
+ *					against machines running Solaris,
+ *					and seems to result in general
+ *					improvement.
+ *	Stefan Magdalinski	:	adjusted tcp_readable() to fix FIONREAD
+ *	Willy Konynenberg	:	Transparent proxying support.
+ *	Mike McLagan		:	Routing by source
+ *		Keith Owens	:	Do proper merging with partial SKB's in
+ *					tcp_do_sendmsg to avoid burstiness.
+ *		Eric Schenk	:	Fix fast close down bug with
+ *					shutdown() followed by close().
+ *		Andi Kleen 	:	Make poll agree with SIGIO
+ *	Salvatore Sanfilippo	:	Support SO_LINGER with linger == 1 and
+ *					lingertime == 0 (RFC 793 ABORT Call)
+ *	Hirokazu Takahashi	:	Use copy_from_user() instead of
+ *					csum_and_copy_from_user() if possible.
+ *
+ * Description of States:
+ *
+ *	TCP_SYN_SENT		sent a connection request, waiting for ack
+ *
+ *	TCP_SYN_RECV		received a connection request, sent ack,
+ *				waiting for final ack in three-way handshake.
+ *
+ *	TCP_ESTABLISHED		connection established
+ *
+ *	TCP_FIN_WAIT1		our side has shutdown, waiting to complete
+ *				transmission of remaining buffered data
+ *
+ *	TCP_FIN_WAIT2		all buffered data sent, waiting for remote
+ *				to shutdown
+ *
+ *	TCP_CLOSING		both sides have shutdown but we still have
+ *				data we have to finish sending
+ *
+ *	TCP_TIME_WAIT		timeout to catch resent junk before entering
+ *				closed, can only be entered from FIN_WAIT2
+ *				or CLOSING.  Required because the other end
+ *				may not have gotten our last ACK causing it
+ *				to retransmit the data packet (which we ignore)
+ *
+ *	TCP_CLOSE_WAIT		remote side has shutdown and is waiting for
+ *				us to finish writing our data and to shutdown
+ *				(we have to close() to move on to LAST_ACK)
+ *
+ *	TCP_LAST_ACK		out side has shutdown after remote has
+ *				shutdown.  There may still be data in our
+ *				buffer that we have to finish sending
+ *
+ *	TCP_CLOSE		socket is finished
+ */
+
+#define pr_fmt(fmt) "TCP: " fmt
+
+#include <crypto/hash.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/fcntl.h>
+#include <linux/poll.h>
+#include <linux/inet_diag.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/skbuff.h>
+#include <linux/scatterlist.h>
+#include <linux/splice.h>
+#include <linux/net.h>
+#include <linux/socket.h>
+#include <linux/random.h>
+#include <linux/memblock.h>
+#include <linux/highmem.h>
+#include <linux/cache.h>
+#include <linux/err.h>
+#include <linux/time.h>
+#include <linux/slab.h>
+#include <linux/errqueue.h>
+#include <linux/static_key.h>
+#include <linux/btf.h>
+
+#include <net/icmp.h>
+#include <net/inet_common.h>
+#include <net/tcp.h>
+#include <net/mptcp.h>
+#include <net/xfrm.h>
+#include <net/ip.h>
+#include <net/sock.h>
+
+#include <linux/uaccess.h>
+#include <asm/ioctls.h>
+#include <net/busy_poll.h>
+
+/* Track pending CMSGs. */
+enum {
+	TCP_CMSG_INQ = 1,
+	TCP_CMSG_TS = 2
+};
+
+DEFINE_PER_CPU(unsigned int, tcp_orphan_count);
+EXPORT_PER_CPU_SYMBOL_GPL(tcp_orphan_count);
+
+long sysctl_tcp_mem[3] __read_mostly;
+EXPORT_SYMBOL(sysctl_tcp_mem);
+
+atomic_long_t tcp_memory_allocated ____cacheline_aligned_in_smp;	/* Current allocated memory. */
+EXPORT_SYMBOL(tcp_memory_allocated);
+DEFINE_PER_CPU(int, tcp_memory_per_cpu_fw_alloc);
+EXPORT_PER_CPU_SYMBOL_GPL(tcp_memory_per_cpu_fw_alloc);
+
+#if IS_ENABLED(CONFIG_SMC)
+DEFINE_STATIC_KEY_FALSE(tcp_have_smc);
+EXPORT_SYMBOL(tcp_have_smc);
+#endif
+
+/*
+ * Current number of TCP sockets.
+ */
+struct percpu_counter tcp_sockets_allocated ____cacheline_aligned_in_smp;
+EXPORT_SYMBOL(tcp_sockets_allocated);
+
+/*
+ * TCP splice context
+ */
+struct tcp_splice_state {
+	struct pipe_inode_info *pipe;
+	size_t len;
+	unsigned int flags;
+};
+
+/*
+ * Pressure flag: try to collapse.
+ * Technical note: it is used by multiple contexts non atomically.
+ * All the __sk_mem_schedule() is of this nature: accounting
+ * is strict, actions are advisory and have some latency.
+ */
+unsigned long tcp_memory_pressure __read_mostly;
+EXPORT_SYMBOL_GPL(tcp_memory_pressure);
+
+void tcp_enter_memory_pressure(struct sock *sk)
+{
+	unsigned long val;
+
+	if (READ_ONCE(tcp_memory_pressure))
+		return;
+	val = jiffies;
+
+	if (!val)
+		val--;
+	if (!cmpxchg(&tcp_memory_pressure, 0, val))
+		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMEMORYPRESSURES);
+}
+EXPORT_SYMBOL_GPL(tcp_enter_memory_pressure);
+
+void tcp_leave_memory_pressure(struct sock *sk)
+{
+	unsigned long val;
+
+	if (!READ_ONCE(tcp_memory_pressure))
+		return;
+	val = xchg(&tcp_memory_pressure, 0);
+	if (val)
+		NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPMEMORYPRESSURESCHRONO,
+			      jiffies_to_msecs(jiffies - val));
+}
+EXPORT_SYMBOL_GPL(tcp_leave_memory_pressure);
+
+/* Convert seconds to retransmits based on initial and max timeout */
+static u8 secs_to_retrans(int seconds, int timeout, int rto_max)
+{
+	u8 res = 0;
+
+	if (seconds > 0) {
+		int period = timeout;
+
+		res = 1;
+		while (seconds > period && res < 255) {
+			res++;
+			timeout <<= 1;
+			if (timeout > rto_max)
+				timeout = rto_max;
+			period += timeout;
+		}
+	}
+	return res;
+}
+
+/* Convert retransmits to seconds based on initial and max timeout */
+static int retrans_to_secs(u8 retrans, int timeout, int rto_max)
+{
+	int period = 0;
+
+	if (retrans > 0) {
+		period = timeout;
+		while (--retrans) {
+			timeout <<= 1;
+			if (timeout > rto_max)
+				timeout = rto_max;
+			period += timeout;
+		}
+	}
+	return period;
+}
+
+static u64 tcp_compute_delivery_rate(const struct tcp_sock *tp)
+{
+	u32 rate = READ_ONCE(tp->rate_delivered);
+	u32 intv = READ_ONCE(tp->rate_interval_us);
+	u64 rate64 = 0;
+
+	if (rate && intv) {
+		rate64 = (u64)rate * tp->mss_cache * USEC_PER_SEC;
+		do_div(rate64, intv);
+	}
+	return rate64;
+}
+
+/* Address-family independent initialization for a tcp_sock.
+ *
+ * NOTE: A lot of things set to zero explicitly by call to
+ *       sk_alloc() so need not be done here.
+ */
+void tcp_init_sock(struct sock *sk)
+{
+	struct inet_connection_sock *icsk = inet_csk(sk);
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	tp->out_of_order_queue = RB_ROOT;
+	sk->tcp_rtx_queue = RB_ROOT;
+	tcp_init_xmit_timers(sk);
+	INIT_LIST_HEAD(&tp->tsq_node);
+	INIT_LIST_HEAD(&tp->tsorted_sent_queue);
+
+	icsk->icsk_rto = TCP_TIMEOUT_INIT;
+	icsk->icsk_rto_min = TCP_RTO_MIN;
+	icsk->icsk_delack_max = TCP_DELACK_MAX;
+	tp->mdev_us = jiffies_to_usecs(TCP_TIMEOUT_INIT);
+	minmax_reset(&tp->rtt_min, tcp_jiffies32, ~0U);
+
+	/* So many TCP implementations out there (incorrectly) count the
+	 * initial SYN frame in their delayed-ACK and congestion control
+	 * algorithms that we must have the following bandaid to talk
+	 * efficiently to them.  -DaveM
+	 */
+	tcp_snd_cwnd_set(tp, TCP_INIT_CWND);
+
+	/* There's a bubble in the pipe until at least the first ACK. */
+	tp->app_limited = ~0U;
+	tp->rate_app_limited = 1;
+
+	/* See draft-stevens-tcpca-spec-01 for discussion of the
+	 * initialization of these values.
+	 */
+	tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
+	tp->snd_cwnd_clamp = ~0;
+	tp->mss_cache = TCP_MSS_DEFAULT;
+
+	tp->reordering = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_reordering);
+	tcp_assign_congestion_control(sk);
+
+	tp->tsoffset = 0;
+	tp->rack.reo_wnd_steps = 1;
+
+	sk->sk_write_space = sk_stream_write_space;
+	sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
+
+	icsk->icsk_sync_mss = tcp_sync_mss;
+
+	WRITE_ONCE(sk->sk_sndbuf, READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_wmem[1]));
+	WRITE_ONCE(sk->sk_rcvbuf, READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[1]));
+
+	set_bit(SOCK_SUPPORT_ZC, &sk->sk_socket->flags);
+	sk_sockets_allocated_inc(sk);
+}
+EXPORT_SYMBOL(tcp_init_sock);
+
+static void tcp_tx_timestamp(struct sock *sk, u16 tsflags)
+{
+	struct sk_buff *skb = tcp_write_queue_tail(sk);
+
+	if (tsflags && skb) {
+		struct skb_shared_info *shinfo = skb_shinfo(skb);
+		struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
+
+		sock_tx_timestamp(sk, tsflags, &shinfo->tx_flags);
+		if (tsflags & SOF_TIMESTAMPING_TX_ACK)
+			tcb->txstamp_ack = 1;
+		if (tsflags & SOF_TIMESTAMPING_TX_RECORD_MASK)
+			shinfo->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;
+	}
+}
+
+static bool tcp_stream_is_readable(struct sock *sk, int target)
+{
+	if (tcp_epollin_ready(sk, target))
+		return true;
+	return sk_is_readable(sk);
+}
+
+/*
+ *	Wait for a TCP event.
+ *
+ *	Note that we don't need to lock the socket, as the upper poll layers
+ *	take care of normal races (between the test and the event) and we don't
+ *	go look at any of the socket buffers directly.
+ */
+__poll_t tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
+{
+	__poll_t mask;
+	struct sock *sk = sock->sk;
+	const struct tcp_sock *tp = tcp_sk(sk);
+	u8 shutdown;
+	int state;
+
+	sock_poll_wait(file, sock, wait);
+
+	state = inet_sk_state_load(sk);
+	if (state == TCP_LISTEN)
+		return inet_csk_listen_poll(sk);
+
+	/* Socket is not locked. We are protected from async events
+	 * by poll logic and correct handling of state changes
+	 * made by other threads is impossible in any case.
+	 */
+
+	mask = 0;
+
+	/*
+	 * EPOLLHUP is certainly not done right. But poll() doesn't
+	 * have a notion of HUP in just one direction, and for a
+	 * socket the read side is more interesting.
+	 *
+	 * Some poll() documentation says that EPOLLHUP is incompatible
+	 * with the EPOLLOUT/POLLWR flags, so somebody should check this
+	 * all. But careful, it tends to be safer to return too many
+	 * bits than too few, and you can easily break real applications
+	 * if you don't tell them that something has hung up!
+	 *
+	 * Check-me.
+	 *
+	 * Check number 1. EPOLLHUP is _UNMASKABLE_ event (see UNIX98 and
+	 * our fs/select.c). It means that after we received EOF,
+	 * poll always returns immediately, making impossible poll() on write()
+	 * in state CLOSE_WAIT. One solution is evident --- to set EPOLLHUP
+	 * if and only if shutdown has been made in both directions.
+	 * Actually, it is interesting to look how Solaris and DUX
+	 * solve this dilemma. I would prefer, if EPOLLHUP were maskable,
+	 * then we could set it on SND_SHUTDOWN. BTW examples given
+	 * in Stevens' books assume exactly this behaviour, it explains
+	 * why EPOLLHUP is incompatible with EPOLLOUT.	--ANK
+	 *
+	 * NOTE. Check for TCP_CLOSE is added. The goal is to prevent
+	 * blocking on fresh not-connected or disconnected socket. --ANK
+	 */
+	shutdown = READ_ONCE(sk->sk_shutdown);
+	if (shutdown == SHUTDOWN_MASK || state == TCP_CLOSE)
+		mask |= EPOLLHUP;
+	if (shutdown & RCV_SHUTDOWN)
+		mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP;
+
+	/* Connected or passive Fast Open socket? */
+	if (state != TCP_SYN_SENT &&
+	    (state != TCP_SYN_RECV || rcu_access_pointer(tp->fastopen_rsk))) {
+		int target = sock_rcvlowat(sk, 0, INT_MAX);
+		u16 urg_data = READ_ONCE(tp->urg_data);
+
+		if (unlikely(urg_data) &&
+		    READ_ONCE(tp->urg_seq) == READ_ONCE(tp->copied_seq) &&
+		    !sock_flag(sk, SOCK_URGINLINE))
+			target++;
+
+		if (tcp_stream_is_readable(sk, target))
+			mask |= EPOLLIN | EPOLLRDNORM;
+
+		if (!(shutdown & SEND_SHUTDOWN)) {
+			if (__sk_stream_is_writeable(sk, 1)) {
+				mask |= EPOLLOUT | EPOLLWRNORM;
+			} else {  /* send SIGIO later */
+				sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
+				set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
+
+				/* Race breaker. If space is freed after
+				 * wspace test but before the flags are set,
+				 * IO signal will be lost. Memory barrier
+				 * pairs with the input side.
+				 */
+				smp_mb__after_atomic();
+				if (__sk_stream_is_writeable(sk, 1))
+					mask |= EPOLLOUT | EPOLLWRNORM;
+			}
+		} else
+			mask |= EPOLLOUT | EPOLLWRNORM;
+
+		if (urg_data & TCP_URG_VALID)
+			mask |= EPOLLPRI;
+	} else if (state == TCP_SYN_SENT && inet_sk(sk)->defer_connect) {
+		/* Active TCP fastopen socket with defer_connect
+		 * Return EPOLLOUT so application can call write()
+		 * in order for kernel to generate SYN+data
+		 */
+		mask |= EPOLLOUT | EPOLLWRNORM;
+	}
+	/* This barrier is coupled with smp_wmb() in tcp_reset() */
+	smp_rmb();
+	if (sk->sk_err || !skb_queue_empty_lockless(&sk->sk_error_queue))
+		mask |= EPOLLERR;
+
+	return mask;
+}
+EXPORT_SYMBOL(tcp_poll);
+
+int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	int answ;
+	bool slow;
+
+	switch (cmd) {
+	case SIOCINQ:
+		if (sk->sk_state == TCP_LISTEN)
+			return -EINVAL;
+
+		slow = lock_sock_fast(sk);
+		answ = tcp_inq(sk);
+		unlock_sock_fast(sk, slow);
+		break;
+	case SIOCATMARK:
+		answ = READ_ONCE(tp->urg_data) &&
+		       READ_ONCE(tp->urg_seq) == READ_ONCE(tp->copied_seq);
+		break;
+	case SIOCOUTQ:
+		if (sk->sk_state == TCP_LISTEN)
+			return -EINVAL;
+
+		if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
+			answ = 0;
+		else
+			answ = READ_ONCE(tp->write_seq) - tp->snd_una;
+		break;
+	case SIOCOUTQNSD:
+		if (sk->sk_state == TCP_LISTEN)
+			return -EINVAL;
+
+		if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
+			answ = 0;
+		else
+			answ = READ_ONCE(tp->write_seq) -
+			       READ_ONCE(tp->snd_nxt);
+		break;
+	default:
+		return -ENOIOCTLCMD;
+	}
+
+	return put_user(answ, (int __user *)arg);
+}
+EXPORT_SYMBOL(tcp_ioctl);
+
+void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
+{
+	TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH;
+	tp->pushed_seq = tp->write_seq;
+}
+
+static inline bool forced_push(const struct tcp_sock *tp)
+{
+	return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
+}
+
+void tcp_skb_entail(struct sock *sk, struct sk_buff *skb)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
+
+	tcb->seq     = tcb->end_seq = tp->write_seq;
+	tcb->tcp_flags = TCPHDR_ACK;
+	__skb_header_release(skb);
+	tcp_add_write_queue_tail(sk, skb);
+	sk_wmem_queued_add(sk, skb->truesize);
+	sk_mem_charge(sk, skb->truesize);
+	if (tp->nonagle & TCP_NAGLE_PUSH)
+		tp->nonagle &= ~TCP_NAGLE_PUSH;
+
+	tcp_slow_start_after_idle_check(sk);
+}
+
+static inline void tcp_mark_urg(struct tcp_sock *tp, int flags)
+{
+	if (flags & MSG_OOB)
+		tp->snd_up = tp->write_seq;
+}
+
+/* If a not yet filled skb is pushed, do not send it if
+ * we have data packets in Qdisc or NIC queues :
+ * Because TX completion will happen shortly, it gives a chance
+ * to coalesce future sendmsg() payload into this skb, without
+ * need for a timer, and with no latency trade off.
+ * As packets containing data payload have a bigger truesize
+ * than pure acks (dataless) packets, the last checks prevent
+ * autocorking if we only have an ACK in Qdisc/NIC queues,
+ * or if TX completion was delayed after we processed ACK packet.
+ */
+static bool tcp_should_autocork(struct sock *sk, struct sk_buff *skb,
+				int size_goal)
+{
+	return skb->len < size_goal &&
+	       READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_autocorking) &&
+	       !tcp_rtx_queue_empty(sk) &&
+	       refcount_read(&sk->sk_wmem_alloc) > skb->truesize &&
+	       tcp_skb_can_collapse_to(skb);
+}
+
+void tcp_push(struct sock *sk, int flags, int mss_now,
+	      int nonagle, int size_goal)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct sk_buff *skb;
+
+	skb = tcp_write_queue_tail(sk);
+	if (!skb)
+		return;
+	if (!(flags & MSG_MORE) || forced_push(tp))
+		tcp_mark_push(tp, skb);
+
+	tcp_mark_urg(tp, flags);
+
+	if (tcp_should_autocork(sk, skb, size_goal)) {
+
+		/* avoid atomic op if TSQ_THROTTLED bit is already set */
+		if (!test_bit(TSQ_THROTTLED, &sk->sk_tsq_flags)) {
+			NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAUTOCORKING);
+			set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags);
+			smp_mb__after_atomic();
+		}
+		/* It is possible TX completion already happened
+		 * before we set TSQ_THROTTLED.
+		 */
+		if (refcount_read(&sk->sk_wmem_alloc) > skb->truesize)
+			return;
+	}
+
+	if (flags & MSG_MORE)
+		nonagle = TCP_NAGLE_CORK;
+
+	__tcp_push_pending_frames(sk, mss_now, nonagle);
+}
+
+static int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
+				unsigned int offset, size_t len)
+{
+	struct tcp_splice_state *tss = rd_desc->arg.data;
+	int ret;
+
+	ret = skb_splice_bits(skb, skb->sk, offset, tss->pipe,
+			      min(rd_desc->count, len), tss->flags);
+	if (ret > 0)
+		rd_desc->count -= ret;
+	return ret;
+}
+
+static int __tcp_splice_read(struct sock *sk, struct tcp_splice_state *tss)
+{
+	/* Store TCP splice context information in read_descriptor_t. */
+	read_descriptor_t rd_desc = {
+		.arg.data = tss,
+		.count	  = tss->len,
+	};
+
+	return tcp_read_sock(sk, &rd_desc, tcp_splice_data_recv);
+}
+
+/**
+ *  tcp_splice_read - splice data from TCP socket to a pipe
+ * @sock:	socket to splice from
+ * @ppos:	position (not valid)
+ * @pipe:	pipe to splice to
+ * @len:	number of bytes to splice
+ * @flags:	splice modifier flags
+ *
+ * Description:
+ *    Will read pages from given socket and fill them into a pipe.
+ *
+ **/
+ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
+			struct pipe_inode_info *pipe, size_t len,
+			unsigned int flags)
+{
+	struct sock *sk = sock->sk;
+	struct tcp_splice_state tss = {
+		.pipe = pipe,
+		.len = len,
+		.flags = flags,
+	};
+	long timeo;
+	ssize_t spliced;
+	int ret;
+
+	sock_rps_record_flow(sk);
+	/*
+	 * We can't seek on a socket input
+	 */
+	if (unlikely(*ppos))
+		return -ESPIPE;
+
+	ret = spliced = 0;
+
+	lock_sock(sk);
+
+	timeo = sock_rcvtimeo(sk, sock->file->f_flags & O_NONBLOCK);
+	while (tss.len) {
+		ret = __tcp_splice_read(sk, &tss);
+		if (ret < 0)
+			break;
+		else if (!ret) {
+			if (spliced)
+				break;
+			if (sock_flag(sk, SOCK_DONE))
+				break;
+			if (sk->sk_err) {
+				ret = sock_error(sk);
+				break;
+			}
+			if (sk->sk_shutdown & RCV_SHUTDOWN)
+				break;
+			if (sk->sk_state == TCP_CLOSE) {
+				/*
+				 * This occurs when user tries to read
+				 * from never connected socket.
+				 */
+				ret = -ENOTCONN;
+				break;
+			}
+			if (!timeo) {
+				ret = -EAGAIN;
+				break;
+			}
+			/* if __tcp_splice_read() got nothing while we have
+			 * an skb in receive queue, we do not want to loop.
+			 * This might happen with URG data.
+			 */
+			if (!skb_queue_empty(&sk->sk_receive_queue))
+				break;
+			ret = sk_wait_data(sk, &timeo, NULL);
+			if (ret < 0)
+				break;
+			if (signal_pending(current)) {
+				ret = sock_intr_errno(timeo);
+				break;
+			}
+			continue;
+		}
+		tss.len -= ret;
+		spliced += ret;
+
+		if (!timeo)
+			break;
+		release_sock(sk);
+		lock_sock(sk);
+
+		if (sk->sk_err || sk->sk_state == TCP_CLOSE ||
+		    (sk->sk_shutdown & RCV_SHUTDOWN) ||
+		    signal_pending(current))
+			break;
+	}
+
+	release_sock(sk);
+
+	if (spliced)
+		return spliced;
+
+	return ret;
+}
+EXPORT_SYMBOL(tcp_splice_read);
+
+struct sk_buff *tcp_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp,
+				     bool force_schedule)
+{
+	struct sk_buff *skb;
+
+	skb = alloc_skb_fclone(size + MAX_TCP_HEADER, gfp);
+	if (likely(skb)) {
+		bool mem_scheduled;
+
+		skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
+		if (force_schedule) {
+			mem_scheduled = true;
+			sk_forced_mem_schedule(sk, skb->truesize);
+		} else {
+			mem_scheduled = sk_wmem_schedule(sk, skb->truesize);
+		}
+		if (likely(mem_scheduled)) {
+			skb_reserve(skb, MAX_TCP_HEADER);
+			skb->ip_summed = CHECKSUM_PARTIAL;
+			INIT_LIST_HEAD(&skb->tcp_tsorted_anchor);
+			return skb;
+		}
+		__kfree_skb(skb);
+	} else {
+		sk->sk_prot->enter_memory_pressure(sk);
+		sk_stream_moderate_sndbuf(sk);
+	}
+	return NULL;
+}
+
+static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now,
+				       int large_allowed)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	u32 new_size_goal, size_goal;
+
+	if (!large_allowed)
+		return mss_now;
+
+	/* Note : tcp_tso_autosize() will eventually split this later */
+	new_size_goal = tcp_bound_to_half_wnd(tp, sk->sk_gso_max_size);
+
+	/* We try hard to avoid divides here */
+	size_goal = tp->gso_segs * mss_now;
+	if (unlikely(new_size_goal < size_goal ||
+		     new_size_goal >= size_goal + mss_now)) {
+		tp->gso_segs = min_t(u16, new_size_goal / mss_now,
+				     sk->sk_gso_max_segs);
+		size_goal = tp->gso_segs * mss_now;
+	}
+
+	return max(size_goal, mss_now);
+}
+
+int tcp_send_mss(struct sock *sk, int *size_goal, int flags)
+{
+	int mss_now;
+
+	mss_now = tcp_current_mss(sk);
+	*size_goal = tcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB));
+
+	return mss_now;
+}
+
+/* In some cases, both sendpage() and sendmsg() could have added
+ * an skb to the write queue, but failed adding payload on it.
+ * We need to remove it to consume less memory, but more
+ * importantly be able to generate EPOLLOUT for Edge Trigger epoll()
+ * users.
+ */
+void tcp_remove_empty_skb(struct sock *sk)
+{
+	struct sk_buff *skb = tcp_write_queue_tail(sk);
+
+	if (skb && TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) {
+		tcp_unlink_write_queue(skb, sk);
+		if (tcp_write_queue_empty(sk))
+			tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
+		tcp_wmem_free_skb(sk, skb);
+	}
+}
+
+/* skb changing from pure zc to mixed, must charge zc */
+static int tcp_downgrade_zcopy_pure(struct sock *sk, struct sk_buff *skb)
+{
+	if (unlikely(skb_zcopy_pure(skb))) {
+		u32 extra = skb->truesize -
+			    SKB_TRUESIZE(skb_end_offset(skb));
+
+		if (!sk_wmem_schedule(sk, extra))
+			return -ENOMEM;
+
+		sk_mem_charge(sk, extra);
+		skb_shinfo(skb)->flags &= ~SKBFL_PURE_ZEROCOPY;
+	}
+	return 0;
+}
+
+
+static int tcp_wmem_schedule(struct sock *sk, int copy)
+{
+	int left;
+
+	if (likely(sk_wmem_schedule(sk, copy)))
+		return copy;
+
+	/* We could be in trouble if we have nothing queued.
+	 * Use whatever is left in sk->sk_forward_alloc and tcp_wmem[0]
+	 * to guarantee some progress.
+	 */
+	left = sock_net(sk)->ipv4.sysctl_tcp_wmem[0] - sk->sk_wmem_queued;
+	if (left > 0)
+		sk_forced_mem_schedule(sk, min(left, copy));
+	return min(copy, sk->sk_forward_alloc);
+}
+
+static struct sk_buff *tcp_build_frag(struct sock *sk, int size_goal, int flags,
+				      struct page *page, int offset, size_t *size)
+{
+	struct sk_buff *skb = tcp_write_queue_tail(sk);
+	struct tcp_sock *tp = tcp_sk(sk);
+	bool can_coalesce;
+	int copy, i;
+
+	if (!skb || (copy = size_goal - skb->len) <= 0 ||
+	    !tcp_skb_can_collapse_to(skb)) {
+new_segment:
+		if (!sk_stream_memory_free(sk))
+			return NULL;
+
+		skb = tcp_stream_alloc_skb(sk, 0, sk->sk_allocation,
+					   tcp_rtx_and_write_queues_empty(sk));
+		if (!skb)
+			return NULL;
+
+#ifdef CONFIG_TLS_DEVICE
+		skb->decrypted = !!(flags & MSG_SENDPAGE_DECRYPTED);
+#endif
+		tcp_skb_entail(sk, skb);
+		copy = size_goal;
+	}
+
+	if (copy > *size)
+		copy = *size;
+
+	i = skb_shinfo(skb)->nr_frags;
+	can_coalesce = skb_can_coalesce(skb, i, page, offset);
+	if (!can_coalesce && i >= READ_ONCE(sysctl_max_skb_frags)) {
+		tcp_mark_push(tp, skb);
+		goto new_segment;
+	}
+	if (tcp_downgrade_zcopy_pure(sk, skb))
+		return NULL;
+
+	copy = tcp_wmem_schedule(sk, copy);
+	if (!copy)
+		return NULL;
+
+	if (can_coalesce) {
+		skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
+	} else {
+		get_page(page);
+		skb_fill_page_desc_noacc(skb, i, page, offset, copy);
+	}
+
+	if (!(flags & MSG_NO_SHARED_FRAGS))
+		skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
+
+	skb->len += copy;
+	skb->data_len += copy;
+	skb->truesize += copy;
+	sk_wmem_queued_add(sk, copy);
+	sk_mem_charge(sk, copy);
+	WRITE_ONCE(tp->write_seq, tp->write_seq + copy);
+	TCP_SKB_CB(skb)->end_seq += copy;
+	tcp_skb_pcount_set(skb, 0);
+
+	*size = copy;
+	return skb;
+}
+
+ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
+			 size_t size, int flags)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	int mss_now, size_goal;
+	int err;
+	ssize_t copied;
+	long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
+
+	if (IS_ENABLED(CONFIG_DEBUG_VM) &&
+	    WARN_ONCE(!sendpage_ok(page),
+		      "page must not be a Slab one and have page_count > 0"))
+		return -EINVAL;
+
+	/* Wait for a connection to finish. One exception is TCP Fast Open
+	 * (passive side) where data is allowed to be sent before a connection
+	 * is fully established.
+	 */
+	if (((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) &&
+	    !tcp_passive_fastopen(sk)) {
+		err = sk_stream_wait_connect(sk, &timeo);
+		if (err != 0)
+			goto out_err;
+	}
+
+	sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
+
+	mss_now = tcp_send_mss(sk, &size_goal, flags);
+	copied = 0;
+
+	err = -EPIPE;
+	if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
+		goto out_err;
+
+	while (size > 0) {
+		struct sk_buff *skb;
+		size_t copy = size;
+
+		skb = tcp_build_frag(sk, size_goal, flags, page, offset, &copy);
+		if (!skb)
+			goto wait_for_space;
+
+		if (!copied)
+			TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
+
+		copied += copy;
+		offset += copy;
+		size -= copy;
+		if (!size)
+			goto out;
+
+		if (skb->len < size_goal || (flags & MSG_OOB))
+			continue;
+
+		if (forced_push(tp)) {
+			tcp_mark_push(tp, skb);
+			__tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
+		} else if (skb == tcp_send_head(sk))
+			tcp_push_one(sk, mss_now);
+		continue;
+
+wait_for_space:
+		set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
+		tcp_push(sk, flags & ~MSG_MORE, mss_now,
+			 TCP_NAGLE_PUSH, size_goal);
+
+		err = sk_stream_wait_memory(sk, &timeo);
+		if (err != 0)
+			goto do_error;
+
+		mss_now = tcp_send_mss(sk, &size_goal, flags);
+	}
+
+out:
+	if (copied) {
+		tcp_tx_timestamp(sk, sk->sk_tsflags);
+		if (!(flags & MSG_SENDPAGE_NOTLAST))
+			tcp_push(sk, flags, mss_now, tp->nonagle, size_goal);
+	}
+	return copied;
+
+do_error:
+	tcp_remove_empty_skb(sk);
+	if (copied)
+		goto out;
+out_err:
+	/* make sure we wake any epoll edge trigger waiter */
+	if (unlikely(tcp_rtx_and_write_queues_empty(sk) && err == -EAGAIN)) {
+		sk->sk_write_space(sk);
+		tcp_chrono_stop(sk, TCP_CHRONO_SNDBUF_LIMITED);
+	}
+	return sk_stream_error(sk, flags, err);
+}
+EXPORT_SYMBOL_GPL(do_tcp_sendpages);
+
+int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset,
+			size_t size, int flags)
+{
+	if (!(sk->sk_route_caps & NETIF_F_SG))
+		return sock_no_sendpage_locked(sk, page, offset, size, flags);
+
+	tcp_rate_check_app_limited(sk);  /* is sending application-limited? */
+
+	return do_tcp_sendpages(sk, page, offset, size, flags);
+}
+EXPORT_SYMBOL_GPL(tcp_sendpage_locked);
+
+int tcp_sendpage(struct sock *sk, struct page *page, int offset,
+		 size_t size, int flags)
+{
+	int ret;
+
+	lock_sock(sk);
+	ret = tcp_sendpage_locked(sk, page, offset, size, flags);
+	release_sock(sk);
+
+	return ret;
+}
+EXPORT_SYMBOL(tcp_sendpage);
+
+void tcp_free_fastopen_req(struct tcp_sock *tp)
+{
+	if (tp->fastopen_req) {
+		kfree(tp->fastopen_req);
+		tp->fastopen_req = NULL;
+	}
+}
+
+int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, int *copied,
+			 size_t size, struct ubuf_info *uarg)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct inet_sock *inet = inet_sk(sk);
+	struct sockaddr *uaddr = msg->msg_name;
+	int err, flags;
+
+	if (!(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fastopen) &
+	      TFO_CLIENT_ENABLE) ||
+	    (uaddr && msg->msg_namelen >= sizeof(uaddr->sa_family) &&
+	     uaddr->sa_family == AF_UNSPEC))
+		return -EOPNOTSUPP;
+	if (tp->fastopen_req)
+		return -EALREADY; /* Another Fast Open is in progress */
+
+	tp->fastopen_req = kzalloc(sizeof(struct tcp_fastopen_request),
+				   sk->sk_allocation);
+	if (unlikely(!tp->fastopen_req))
+		return -ENOBUFS;
+	tp->fastopen_req->data = msg;
+	tp->fastopen_req->size = size;
+	tp->fastopen_req->uarg = uarg;
+
+	if (inet->defer_connect) {
+		err = tcp_connect(sk);
+		/* Same failure procedure as in tcp_v4/6_connect */
+		if (err) {
+			tcp_set_state(sk, TCP_CLOSE);
+			inet->inet_dport = 0;
+			sk->sk_route_caps = 0;
+		}
+	}
+	flags = (msg->msg_flags & MSG_DONTWAIT) ? O_NONBLOCK : 0;
+	err = __inet_stream_connect(sk->sk_socket, uaddr,
+				    msg->msg_namelen, flags, 1);
+	/* fastopen_req could already be freed in __inet_stream_connect
+	 * if the connection times out or gets rst
+	 */
+	if (tp->fastopen_req) {
+		*copied = tp->fastopen_req->copied;
+		tcp_free_fastopen_req(tp);
+		inet->defer_connect = 0;
+	}
+	return err;
+}
+
+int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct ubuf_info *uarg = NULL;
+	struct sk_buff *skb;
+	struct sockcm_cookie sockc;
+	int flags, err, copied = 0;
+	int mss_now = 0, size_goal, copied_syn = 0;
+	int process_backlog = 0;
+	bool zc = false;
+	long timeo;
+
+	flags = msg->msg_flags;
+
+	if ((flags & MSG_ZEROCOPY) && size) {
+		skb = tcp_write_queue_tail(sk);
+
+		if (msg->msg_ubuf) {
+			uarg = msg->msg_ubuf;
+			net_zcopy_get(uarg);
+			zc = sk->sk_route_caps & NETIF_F_SG;
+		} else if (sock_flag(sk, SOCK_ZEROCOPY)) {
+			uarg = msg_zerocopy_realloc(sk, size, skb_zcopy(skb));
+			if (!uarg) {
+				err = -ENOBUFS;
+				goto out_err;
+			}
+			zc = sk->sk_route_caps & NETIF_F_SG;
+			if (!zc)
+				uarg_to_msgzc(uarg)->zerocopy = 0;
+		}
+	}
+
+	if (unlikely(flags & MSG_FASTOPEN || inet_sk(sk)->defer_connect) &&
+	    !tp->repair) {
+		err = tcp_sendmsg_fastopen(sk, msg, &copied_syn, size, uarg);
+		if (err == -EINPROGRESS && copied_syn > 0)
+			goto out;
+		else if (err)
+			goto out_err;
+	}
+
+	timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
+
+	tcp_rate_check_app_limited(sk);  /* is sending application-limited? */
+
+	/* Wait for a connection to finish. One exception is TCP Fast Open
+	 * (passive side) where data is allowed to be sent before a connection
+	 * is fully established.
+	 */
+	if (((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) &&
+	    !tcp_passive_fastopen(sk)) {
+		err = sk_stream_wait_connect(sk, &timeo);
+		if (err != 0)
+			goto do_error;
+	}
+
+	if (unlikely(tp->repair)) {
+		if (tp->repair_queue == TCP_RECV_QUEUE) {
+			copied = tcp_send_rcvq(sk, msg, size);
+			goto out_nopush;
+		}
+
+		err = -EINVAL;
+		if (tp->repair_queue == TCP_NO_QUEUE)
+			goto out_err;
+
+		/* 'common' sending to sendq */
+	}
+
+	sockcm_init(&sockc, sk);
+	if (msg->msg_controllen) {
+		err = sock_cmsg_send(sk, msg, &sockc);
+		if (unlikely(err)) {
+			err = -EINVAL;
+			goto out_err;
+		}
+	}
+
+	/* This should be in poll */
+	sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
+
+	/* Ok commence sending. */
+	copied = 0;
+
+restart:
+	mss_now = tcp_send_mss(sk, &size_goal, flags);
+
+	err = -EPIPE;
+	if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
+		goto do_error;
+
+	while (msg_data_left(msg)) {
+		int copy = 0;
+
+		skb = tcp_write_queue_tail(sk);
+		if (skb)
+			copy = size_goal - skb->len;
+
+		if (copy <= 0 || !tcp_skb_can_collapse_to(skb)) {
+			bool first_skb;
+
+new_segment:
+			if (!sk_stream_memory_free(sk))
+				goto wait_for_space;
+
+			if (unlikely(process_backlog >= 16)) {
+				process_backlog = 0;
+				if (sk_flush_backlog(sk))
+					goto restart;
+			}
+			first_skb = tcp_rtx_and_write_queues_empty(sk);
+			skb = tcp_stream_alloc_skb(sk, 0, sk->sk_allocation,
+						   first_skb);
+			if (!skb)
+				goto wait_for_space;
+
+			process_backlog++;
+
+			tcp_skb_entail(sk, skb);
+			copy = size_goal;
+
+			/* All packets are restored as if they have
+			 * already been sent. skb_mstamp_ns isn't set to
+			 * avoid wrong rtt estimation.
+			 */
+			if (tp->repair)
+				TCP_SKB_CB(skb)->sacked |= TCPCB_REPAIRED;
+		}
+
+		/* Try to append data to the end of skb. */
+		if (copy > msg_data_left(msg))
+			copy = msg_data_left(msg);
+
+		if (!zc) {
+			bool merge = true;
+			int i = skb_shinfo(skb)->nr_frags;
+			struct page_frag *pfrag = sk_page_frag(sk);
+
+			if (!sk_page_frag_refill(sk, pfrag))
+				goto wait_for_space;
+
+			if (!skb_can_coalesce(skb, i, pfrag->page,
+					      pfrag->offset)) {
+				if (i >= READ_ONCE(sysctl_max_skb_frags)) {
+					tcp_mark_push(tp, skb);
+					goto new_segment;
+				}
+				merge = false;
+			}
+
+			copy = min_t(int, copy, pfrag->size - pfrag->offset);
+
+			if (unlikely(skb_zcopy_pure(skb) || skb_zcopy_managed(skb))) {
+				if (tcp_downgrade_zcopy_pure(sk, skb))
+					goto wait_for_space;
+				skb_zcopy_downgrade_managed(skb);
+			}
+
+			copy = tcp_wmem_schedule(sk, copy);
+			if (!copy)
+				goto wait_for_space;
+
+			err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
+						       pfrag->page,
+						       pfrag->offset,
+						       copy);
+			if (err)
+				goto do_error;
+
+			/* Update the skb. */
+			if (merge) {
+				skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
+			} else {
+				skb_fill_page_desc(skb, i, pfrag->page,
+						   pfrag->offset, copy);
+				page_ref_inc(pfrag->page);
+			}
+			pfrag->offset += copy;
+		} else {
+			/* First append to a fragless skb builds initial
+			 * pure zerocopy skb
+			 */
+			if (!skb->len)
+				skb_shinfo(skb)->flags |= SKBFL_PURE_ZEROCOPY;
+
+			if (!skb_zcopy_pure(skb)) {
+				copy = tcp_wmem_schedule(sk, copy);
+				if (!copy)
+					goto wait_for_space;
+			}
+
+			err = skb_zerocopy_iter_stream(sk, skb, msg, copy, uarg);
+			if (err == -EMSGSIZE || err == -EEXIST) {
+				tcp_mark_push(tp, skb);
+				goto new_segment;
+			}
+			if (err < 0)
+				goto do_error;
+			copy = err;
+		}
+
+		if (!copied)
+			TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
+
+		WRITE_ONCE(tp->write_seq, tp->write_seq + copy);
+		TCP_SKB_CB(skb)->end_seq += copy;
+		tcp_skb_pcount_set(skb, 0);
+
+		copied += copy;
+		if (!msg_data_left(msg)) {
+			if (unlikely(flags & MSG_EOR))
+				TCP_SKB_CB(skb)->eor = 1;
+			goto out;
+		}
+
+		if (skb->len < size_goal || (flags & MSG_OOB) || unlikely(tp->repair))
+			continue;
+
+		if (forced_push(tp)) {
+			tcp_mark_push(tp, skb);
+			__tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
+		} else if (skb == tcp_send_head(sk))
+			tcp_push_one(sk, mss_now);
+		continue;
+
+wait_for_space:
+		set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
+		if (copied)
+			tcp_push(sk, flags & ~MSG_MORE, mss_now,
+				 TCP_NAGLE_PUSH, size_goal);
+
+		err = sk_stream_wait_memory(sk, &timeo);
+		if (err != 0)
+			goto do_error;
+
+		mss_now = tcp_send_mss(sk, &size_goal, flags);
+	}
+
+out:
+	if (copied) {
+		tcp_tx_timestamp(sk, sockc.tsflags);
+		tcp_push(sk, flags, mss_now, tp->nonagle, size_goal);
+	}
+out_nopush:
+	net_zcopy_put(uarg);
+	return copied + copied_syn;
+
+do_error:
+	tcp_remove_empty_skb(sk);
+
+	if (copied + copied_syn)
+		goto out;
+out_err:
+	net_zcopy_put_abort(uarg, true);
+	err = sk_stream_error(sk, flags, err);
+	/* make sure we wake any epoll edge trigger waiter */
+	if (unlikely(tcp_rtx_and_write_queues_empty(sk) && err == -EAGAIN)) {
+		sk->sk_write_space(sk);
+		tcp_chrono_stop(sk, TCP_CHRONO_SNDBUF_LIMITED);
+	}
+	return err;
+}
+EXPORT_SYMBOL_GPL(tcp_sendmsg_locked);
+
+int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
+{
+	int ret;
+
+	lock_sock(sk);
+	ret = tcp_sendmsg_locked(sk, msg, size);
+	release_sock(sk);
+
+	return ret;
+}
+EXPORT_SYMBOL(tcp_sendmsg);
+
+void tcp_splice_eof(struct socket *sock)
+{
+	struct sock *sk = sock->sk;
+	struct tcp_sock *tp = tcp_sk(sk);
+	int mss_now, size_goal;
+
+	if (!tcp_write_queue_tail(sk))
+		return;
+
+	lock_sock(sk);
+	mss_now = tcp_send_mss(sk, &size_goal, 0);
+	tcp_push(sk, 0, mss_now, tp->nonagle, size_goal);
+	release_sock(sk);
+}
+EXPORT_SYMBOL_GPL(tcp_splice_eof);
+
+/*
+ *	Handle reading urgent data. BSD has very simple semantics for
+ *	this, no blocking and very strange errors 8)
+ */
+
+static int tcp_recv_urg(struct sock *sk, struct msghdr *msg, int len, int flags)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	/* No URG data to read. */
+	if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data ||
+	    tp->urg_data == TCP_URG_READ)
+		return -EINVAL;	/* Yes this is right ! */
+
+	if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE))
+		return -ENOTCONN;
+
+	if (tp->urg_data & TCP_URG_VALID) {
+		int err = 0;
+		char c = tp->urg_data;
+
+		if (!(flags & MSG_PEEK))
+			WRITE_ONCE(tp->urg_data, TCP_URG_READ);
+
+		/* Read urgent data. */
+		msg->msg_flags |= MSG_OOB;
+
+		if (len > 0) {
+			if (!(flags & MSG_TRUNC))
+				err = memcpy_to_msg(msg, &c, 1);
+			len = 1;
+		} else
+			msg->msg_flags |= MSG_TRUNC;
+
+		return err ? -EFAULT : len;
+	}
+
+	if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
+		return 0;
+
+	/* Fixed the recv(..., MSG_OOB) behaviour.  BSD docs and
+	 * the available implementations agree in this case:
+	 * this call should never block, independent of the
+	 * blocking state of the socket.
+	 * Mike <pall@rz.uni-karlsruhe.de>
+	 */
+	return -EAGAIN;
+}
+
+static int tcp_peek_sndq(struct sock *sk, struct msghdr *msg, int len)
+{
+	struct sk_buff *skb;
+	int copied = 0, err = 0;
+
+	/* XXX -- need to support SO_PEEK_OFF */
+
+	skb_rbtree_walk(skb, &sk->tcp_rtx_queue) {
+		err = skb_copy_datagram_msg(skb, 0, msg, skb->len);
+		if (err)
+			return err;
+		copied += skb->len;
+	}
+
+	skb_queue_walk(&sk->sk_write_queue, skb) {
+		err = skb_copy_datagram_msg(skb, 0, msg, skb->len);
+		if (err)
+			break;
+
+		copied += skb->len;
+	}
+
+	return err ?: copied;
+}
+
+/* Clean up the receive buffer for full frames taken by the user,
+ * then send an ACK if necessary.  COPIED is the number of bytes
+ * tcp_recvmsg has given to the user so far, it speeds up the
+ * calculation of whether or not we must ACK for the sake of
+ * a window update.
+ */
+void __tcp_cleanup_rbuf(struct sock *sk, int copied)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	bool time_to_ack = false;
+
+	if (inet_csk_ack_scheduled(sk)) {
+		const struct inet_connection_sock *icsk = inet_csk(sk);
+
+		if (/* Once-per-two-segments ACK was not sent by tcp_input.c */
+		    tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
+		    /*
+		     * If this read emptied read buffer, we send ACK, if
+		     * connection is not bidirectional, user drained
+		     * receive buffer and there was a small segment
+		     * in queue.
+		     */
+		    (copied > 0 &&
+		     ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED2) ||
+		      ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
+		       !inet_csk_in_pingpong_mode(sk))) &&
+		      !atomic_read(&sk->sk_rmem_alloc)))
+			time_to_ack = true;
+	}
+
+	/* We send an ACK if we can now advertise a non-zero window
+	 * which has been raised "significantly".
+	 *
+	 * Even if window raised up to infinity, do not send window open ACK
+	 * in states, where we will not receive more. It is useless.
+	 */
+	if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
+		__u32 rcv_window_now = tcp_receive_window(tp);
+
+		/* Optimize, __tcp_select_window() is not cheap. */
+		if (2*rcv_window_now <= tp->window_clamp) {
+			__u32 new_window = __tcp_select_window(sk);
+
+			/* Send ACK now, if this read freed lots of space
+			 * in our buffer. Certainly, new_window is new window.
+			 * We can advertise it now, if it is not less than current one.
+			 * "Lots" means "at least twice" here.
+			 */
+			if (new_window && new_window >= 2 * rcv_window_now)
+				time_to_ack = true;
+		}
+	}
+	if (time_to_ack)
+		tcp_send_ack(sk);
+}
+
+void tcp_cleanup_rbuf(struct sock *sk, int copied)
+{
+	struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	WARN(skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq),
+	     "cleanup rbuf bug: copied %X seq %X rcvnxt %X\n",
+	     tp->copied_seq, TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt);
+	__tcp_cleanup_rbuf(sk, copied);
+}
+
+static void tcp_eat_recv_skb(struct sock *sk, struct sk_buff *skb)
+{
+	__skb_unlink(skb, &sk->sk_receive_queue);
+	if (likely(skb->destructor == sock_rfree)) {
+		sock_rfree(skb);
+		skb->destructor = NULL;
+		skb->sk = NULL;
+		return skb_attempt_defer_free(skb);
+	}
+	__kfree_skb(skb);
+}
+
+struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
+{
+	struct sk_buff *skb;
+	u32 offset;
+
+	while ((skb = skb_peek(&sk->sk_receive_queue)) != NULL) {
+		offset = seq - TCP_SKB_CB(skb)->seq;
+		if (unlikely(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
+			pr_err_once("%s: found a SYN, please report !\n", __func__);
+			offset--;
+		}
+		if (offset < skb->len || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) {
+			*off = offset;
+			return skb;
+		}
+		/* This looks weird, but this can happen if TCP collapsing
+		 * splitted a fat GRO packet, while we released socket lock
+		 * in skb_splice_bits()
+		 */
+		tcp_eat_recv_skb(sk, skb);
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(tcp_recv_skb);
+
+/*
+ * This routine provides an alternative to tcp_recvmsg() for routines
+ * that would like to handle copying from skbuffs directly in 'sendfile'
+ * fashion.
+ * Note:
+ *	- It is assumed that the socket was locked by the caller.
+ *	- The routine does not block.
+ *	- At present, there is no support for reading OOB data
+ *	  or for 'peeking' the socket using this routine
+ *	  (although both would be easy to implement).
+ */
+int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
+		  sk_read_actor_t recv_actor)
+{
+	struct sk_buff *skb;
+	struct tcp_sock *tp = tcp_sk(sk);
+	u32 seq = tp->copied_seq;
+	u32 offset;
+	int copied = 0;
+
+	if (sk->sk_state == TCP_LISTEN)
+		return -ENOTCONN;
+	while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
+		if (offset < skb->len) {
+			int used;
+			size_t len;
+
+			len = skb->len - offset;
+			/* Stop reading if we hit a patch of urgent data */
+			if (unlikely(tp->urg_data)) {
+				u32 urg_offset = tp->urg_seq - seq;
+				if (urg_offset < len)
+					len = urg_offset;
+				if (!len)
+					break;
+			}
+			used = recv_actor(desc, skb, offset, len);
+			if (used <= 0) {
+				if (!copied)
+					copied = used;
+				break;
+			}
+			if (WARN_ON_ONCE(used > len))
+				used = len;
+			seq += used;
+			copied += used;
+			offset += used;
+
+			/* If recv_actor drops the lock (e.g. TCP splice
+			 * receive) the skb pointer might be invalid when
+			 * getting here: tcp_collapse might have deleted it
+			 * while aggregating skbs from the socket queue.
+			 */
+			skb = tcp_recv_skb(sk, seq - 1, &offset);
+			if (!skb)
+				break;
+			/* TCP coalescing might have appended data to the skb.
+			 * Try to splice more frags
+			 */
+			if (offset + 1 != skb->len)
+				continue;
+		}
+		if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) {
+			tcp_eat_recv_skb(sk, skb);
+			++seq;
+			break;
+		}
+		tcp_eat_recv_skb(sk, skb);
+		if (!desc->count)
+			break;
+		WRITE_ONCE(tp->copied_seq, seq);
+	}
+	WRITE_ONCE(tp->copied_seq, seq);
+
+	tcp_rcv_space_adjust(sk);
+
+	/* Clean up data we have read: This will do ACK frames. */
+	if (copied > 0) {
+		tcp_recv_skb(sk, seq, &offset);
+		tcp_cleanup_rbuf(sk, copied);
+	}
+	return copied;
+}
+EXPORT_SYMBOL(tcp_read_sock);
+
+int tcp_read_skb(struct sock *sk, skb_read_actor_t recv_actor)
+{
+	struct sk_buff *skb;
+	int copied = 0;
+
+	if (sk->sk_state == TCP_LISTEN)
+		return -ENOTCONN;
+
+	while ((skb = skb_peek(&sk->sk_receive_queue)) != NULL) {
+		u8 tcp_flags;
+		int used;
+
+		__skb_unlink(skb, &sk->sk_receive_queue);
+		WARN_ON_ONCE(!skb_set_owner_sk_safe(skb, sk));
+		tcp_flags = TCP_SKB_CB(skb)->tcp_flags;
+		used = recv_actor(sk, skb);
+		if (used < 0) {
+			if (!copied)
+				copied = used;
+			break;
+		}
+		copied += used;
+
+		if (tcp_flags & TCPHDR_FIN)
+			break;
+	}
+	return copied;
+}
+EXPORT_SYMBOL(tcp_read_skb);
+
+void tcp_read_done(struct sock *sk, size_t len)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	u32 seq = tp->copied_seq;
+	struct sk_buff *skb;
+	size_t left;
+	u32 offset;
+
+	if (sk->sk_state == TCP_LISTEN)
+		return;
+
+	left = len;
+	while (left && (skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
+		int used;
+
+		used = min_t(size_t, skb->len - offset, left);
+		seq += used;
+		left -= used;
+
+		if (skb->len > offset + used)
+			break;
+
+		if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) {
+			tcp_eat_recv_skb(sk, skb);
+			++seq;
+			break;
+		}
+		tcp_eat_recv_skb(sk, skb);
+	}
+	WRITE_ONCE(tp->copied_seq, seq);
+
+	tcp_rcv_space_adjust(sk);
+
+	/* Clean up data we have read: This will do ACK frames. */
+	if (left != len)
+		tcp_cleanup_rbuf(sk, len - left);
+}
+EXPORT_SYMBOL(tcp_read_done);
+
+int tcp_peek_len(struct socket *sock)
+{
+	return tcp_inq(sock->sk);
+}
+EXPORT_SYMBOL(tcp_peek_len);
+
+/* Make sure sk_rcvbuf is big enough to satisfy SO_RCVLOWAT hint */
+int tcp_set_rcvlowat(struct sock *sk, int val)
+{
+	int cap;
+
+	if (sk->sk_userlocks & SOCK_RCVBUF_LOCK)
+		cap = sk->sk_rcvbuf >> 1;
+	else
+		cap = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[2]) >> 1;
+	val = min(val, cap);
+	WRITE_ONCE(sk->sk_rcvlowat, val ? : 1);
+
+	/* Check if we need to signal EPOLLIN right now */
+	tcp_data_ready(sk);
+
+	if (sk->sk_userlocks & SOCK_RCVBUF_LOCK)
+		return 0;
+
+	val <<= 1;
+	if (val > sk->sk_rcvbuf) {
+		WRITE_ONCE(sk->sk_rcvbuf, val);
+		tcp_sk(sk)->window_clamp = tcp_win_from_space(sk, val);
+	}
+	return 0;
+}
+EXPORT_SYMBOL(tcp_set_rcvlowat);
+
+void tcp_update_recv_tstamps(struct sk_buff *skb,
+			     struct scm_timestamping_internal *tss)
+{
+	if (skb->tstamp)
+		tss->ts[0] = ktime_to_timespec64(skb->tstamp);
+	else
+		tss->ts[0] = (struct timespec64) {0};
+
+	if (skb_hwtstamps(skb)->hwtstamp)
+		tss->ts[2] = ktime_to_timespec64(skb_hwtstamps(skb)->hwtstamp);
+	else
+		tss->ts[2] = (struct timespec64) {0};
+}
+
+#ifdef CONFIG_MMU
+static const struct vm_operations_struct tcp_vm_ops = {
+};
+
+int tcp_mmap(struct file *file, struct socket *sock,
+	     struct vm_area_struct *vma)
+{
+	if (vma->vm_flags & (VM_WRITE | VM_EXEC))
+		return -EPERM;
+	vma->vm_flags &= ~(VM_MAYWRITE | VM_MAYEXEC);
+
+	/* Instruct vm_insert_page() to not mmap_read_lock(mm) */
+	vma->vm_flags |= VM_MIXEDMAP;
+
+	vma->vm_ops = &tcp_vm_ops;
+	return 0;
+}
+EXPORT_SYMBOL(tcp_mmap);
+
+static skb_frag_t *skb_advance_to_frag(struct sk_buff *skb, u32 offset_skb,
+				       u32 *offset_frag)
+{
+	skb_frag_t *frag;
+
+	if (unlikely(offset_skb >= skb->len))
+		return NULL;
+
+	offset_skb -= skb_headlen(skb);
+	if ((int)offset_skb < 0 || skb_has_frag_list(skb))
+		return NULL;
+
+	frag = skb_shinfo(skb)->frags;
+	while (offset_skb) {
+		if (skb_frag_size(frag) > offset_skb) {
+			*offset_frag = offset_skb;
+			return frag;
+		}
+		offset_skb -= skb_frag_size(frag);
+		++frag;
+	}
+	*offset_frag = 0;
+	return frag;
+}
+
+static bool can_map_frag(const skb_frag_t *frag)
+{
+	return skb_frag_size(frag) == PAGE_SIZE && !skb_frag_off(frag);
+}
+
+static int find_next_mappable_frag(const skb_frag_t *frag,
+				   int remaining_in_skb)
+{
+	int offset = 0;
+
+	if (likely(can_map_frag(frag)))
+		return 0;
+
+	while (offset < remaining_in_skb && !can_map_frag(frag)) {
+		offset += skb_frag_size(frag);
+		++frag;
+	}
+	return offset;
+}
+
+static void tcp_zerocopy_set_hint_for_skb(struct sock *sk,
+					  struct tcp_zerocopy_receive *zc,
+					  struct sk_buff *skb, u32 offset)
+{
+	u32 frag_offset, partial_frag_remainder = 0;
+	int mappable_offset;
+	skb_frag_t *frag;
+
+	/* worst case: skip to next skb. try to improve on this case below */
+	zc->recv_skip_hint = skb->len - offset;
+
+	/* Find the frag containing this offset (and how far into that frag) */
+	frag = skb_advance_to_frag(skb, offset, &frag_offset);
+	if (!frag)
+		return;
+
+	if (frag_offset) {
+		struct skb_shared_info *info = skb_shinfo(skb);
+
+		/* We read part of the last frag, must recvmsg() rest of skb. */
+		if (frag == &info->frags[info->nr_frags - 1])
+			return;
+
+		/* Else, we must at least read the remainder in this frag. */
+		partial_frag_remainder = skb_frag_size(frag) - frag_offset;
+		zc->recv_skip_hint -= partial_frag_remainder;
+		++frag;
+	}
+
+	/* partial_frag_remainder: If part way through a frag, must read rest.
+	 * mappable_offset: Bytes till next mappable frag, *not* counting bytes
+	 * in partial_frag_remainder.
+	 */
+	mappable_offset = find_next_mappable_frag(frag, zc->recv_skip_hint);
+	zc->recv_skip_hint = mappable_offset + partial_frag_remainder;
+}
+
+static int tcp_recvmsg_locked(struct sock *sk, struct msghdr *msg, size_t len,
+			      int flags, struct scm_timestamping_internal *tss,
+			      int *cmsg_flags);
+static int receive_fallback_to_copy(struct sock *sk,
+				    struct tcp_zerocopy_receive *zc, int inq,
+				    struct scm_timestamping_internal *tss)
+{
+	unsigned long copy_address = (unsigned long)zc->copybuf_address;
+	struct msghdr msg = {};
+	struct iovec iov;
+	int err;
+
+	zc->length = 0;
+	zc->recv_skip_hint = 0;
+
+	if (copy_address != zc->copybuf_address)
+		return -EINVAL;
+
+	err = import_single_range(ITER_DEST, (void __user *)copy_address,
+				  inq, &iov, &msg.msg_iter);
+	if (err)
+		return err;
+
+	err = tcp_recvmsg_locked(sk, &msg, inq, MSG_DONTWAIT,
+				 tss, &zc->msg_flags);
+	if (err < 0)
+		return err;
+
+	zc->copybuf_len = err;
+	if (likely(zc->copybuf_len)) {
+		struct sk_buff *skb;
+		u32 offset;
+
+		skb = tcp_recv_skb(sk, tcp_sk(sk)->copied_seq, &offset);
+		if (skb)
+			tcp_zerocopy_set_hint_for_skb(sk, zc, skb, offset);
+	}
+	return 0;
+}
+
+static int tcp_copy_straggler_data(struct tcp_zerocopy_receive *zc,
+				   struct sk_buff *skb, u32 copylen,
+				   u32 *offset, u32 *seq)
+{
+	unsigned long copy_address = (unsigned long)zc->copybuf_address;
+	struct msghdr msg = {};
+	struct iovec iov;
+	int err;
+
+	if (copy_address != zc->copybuf_address)
+		return -EINVAL;
+
+	err = import_single_range(ITER_DEST, (void __user *)copy_address,
+				  copylen, &iov, &msg.msg_iter);
+	if (err)
+		return err;
+	err = skb_copy_datagram_msg(skb, *offset, &msg, copylen);
+	if (err)
+		return err;
+	zc->recv_skip_hint -= copylen;
+	*offset += copylen;
+	*seq += copylen;
+	return (__s32)copylen;
+}
+
+static int tcp_zc_handle_leftover(struct tcp_zerocopy_receive *zc,
+				  struct sock *sk,
+				  struct sk_buff *skb,
+				  u32 *seq,
+				  s32 copybuf_len,
+				  struct scm_timestamping_internal *tss)
+{
+	u32 offset, copylen = min_t(u32, copybuf_len, zc->recv_skip_hint);
+
+	if (!copylen)
+		return 0;
+	/* skb is null if inq < PAGE_SIZE. */
+	if (skb) {
+		offset = *seq - TCP_SKB_CB(skb)->seq;
+	} else {
+		skb = tcp_recv_skb(sk, *seq, &offset);
+		if (TCP_SKB_CB(skb)->has_rxtstamp) {
+			tcp_update_recv_tstamps(skb, tss);
+			zc->msg_flags |= TCP_CMSG_TS;
+		}
+	}
+
+	zc->copybuf_len = tcp_copy_straggler_data(zc, skb, copylen, &offset,
+						  seq);
+	return zc->copybuf_len < 0 ? 0 : copylen;
+}
+
+static int tcp_zerocopy_vm_insert_batch_error(struct vm_area_struct *vma,
+					      struct page **pending_pages,
+					      unsigned long pages_remaining,
+					      unsigned long *address,
+					      u32 *length,
+					      u32 *seq,
+					      struct tcp_zerocopy_receive *zc,
+					      u32 total_bytes_to_map,
+					      int err)
+{
+	/* At least one page did not map. Try zapping if we skipped earlier. */
+	if (err == -EBUSY &&
+	    zc->flags & TCP_RECEIVE_ZEROCOPY_FLAG_TLB_CLEAN_HINT) {
+		u32 maybe_zap_len;
+
+		maybe_zap_len = total_bytes_to_map -  /* All bytes to map */
+				*length + /* Mapped or pending */
+				(pages_remaining * PAGE_SIZE); /* Failed map. */
+		zap_page_range(vma, *address, maybe_zap_len);
+		err = 0;
+	}
+
+	if (!err) {
+		unsigned long leftover_pages = pages_remaining;
+		int bytes_mapped;
+
+		/* We called zap_page_range, try to reinsert. */
+		err = vm_insert_pages(vma, *address,
+				      pending_pages,
+				      &pages_remaining);
+		bytes_mapped = PAGE_SIZE * (leftover_pages - pages_remaining);
+		*seq += bytes_mapped;
+		*address += bytes_mapped;
+	}
+	if (err) {
+		/* Either we were unable to zap, OR we zapped, retried an
+		 * insert, and still had an issue. Either ways, pages_remaining
+		 * is the number of pages we were unable to map, and we unroll
+		 * some state we speculatively touched before.
+		 */
+		const int bytes_not_mapped = PAGE_SIZE * pages_remaining;
+
+		*length -= bytes_not_mapped;
+		zc->recv_skip_hint += bytes_not_mapped;
+	}
+	return err;
+}
+
+static int tcp_zerocopy_vm_insert_batch(struct vm_area_struct *vma,
+					struct page **pages,
+					unsigned int pages_to_map,
+					unsigned long *address,
+					u32 *length,
+					u32 *seq,
+					struct tcp_zerocopy_receive *zc,
+					u32 total_bytes_to_map)
+{
+	unsigned long pages_remaining = pages_to_map;
+	unsigned int pages_mapped;
+	unsigned int bytes_mapped;
+	int err;
+
+	err = vm_insert_pages(vma, *address, pages, &pages_remaining);
+	pages_mapped = pages_to_map - (unsigned int)pages_remaining;
+	bytes_mapped = PAGE_SIZE * pages_mapped;
+	/* Even if vm_insert_pages fails, it may have partially succeeded in
+	 * mapping (some but not all of the pages).
+	 */
+	*seq += bytes_mapped;
+	*address += bytes_mapped;
+
+	if (likely(!err))
+		return 0;
+
+	/* Error: maybe zap and retry + rollback state for failed inserts. */
+	return tcp_zerocopy_vm_insert_batch_error(vma, pages + pages_mapped,
+		pages_remaining, address, length, seq, zc, total_bytes_to_map,
+		err);
+}
+
+#define TCP_VALID_ZC_MSG_FLAGS   (TCP_CMSG_TS)
+static void tcp_zc_finalize_rx_tstamp(struct sock *sk,
+				      struct tcp_zerocopy_receive *zc,
+				      struct scm_timestamping_internal *tss)
+{
+	unsigned long msg_control_addr;
+	struct msghdr cmsg_dummy;
+
+	msg_control_addr = (unsigned long)zc->msg_control;
+	cmsg_dummy.msg_control = (void *)msg_control_addr;
+	cmsg_dummy.msg_controllen =
+		(__kernel_size_t)zc->msg_controllen;
+	cmsg_dummy.msg_flags = in_compat_syscall()
+		? MSG_CMSG_COMPAT : 0;
+	cmsg_dummy.msg_control_is_user = true;
+	zc->msg_flags = 0;
+	if (zc->msg_control == msg_control_addr &&
+	    zc->msg_controllen == cmsg_dummy.msg_controllen) {
+		tcp_recv_timestamp(&cmsg_dummy, sk, tss);
+		zc->msg_control = (__u64)
+			((uintptr_t)cmsg_dummy.msg_control);
+		zc->msg_controllen =
+			(__u64)cmsg_dummy.msg_controllen;
+		zc->msg_flags = (__u32)cmsg_dummy.msg_flags;
+	}
+}
+
+#define TCP_ZEROCOPY_PAGE_BATCH_SIZE 32
+static int tcp_zerocopy_receive(struct sock *sk,
+				struct tcp_zerocopy_receive *zc,
+				struct scm_timestamping_internal *tss)
+{
+	u32 length = 0, offset, vma_len, avail_len, copylen = 0;
+	unsigned long address = (unsigned long)zc->address;
+	struct page *pages[TCP_ZEROCOPY_PAGE_BATCH_SIZE];
+	s32 copybuf_len = zc->copybuf_len;
+	struct tcp_sock *tp = tcp_sk(sk);
+	const skb_frag_t *frags = NULL;
+	unsigned int pages_to_map = 0;
+	struct vm_area_struct *vma;
+	struct sk_buff *skb = NULL;
+	u32 seq = tp->copied_seq;
+	u32 total_bytes_to_map;
+	int inq = tcp_inq(sk);
+	int ret;
+
+	zc->copybuf_len = 0;
+	zc->msg_flags = 0;
+
+	if (address & (PAGE_SIZE - 1) || address != zc->address)
+		return -EINVAL;
+
+	if (sk->sk_state == TCP_LISTEN)
+		return -ENOTCONN;
+
+	sock_rps_record_flow(sk);
+
+	if (inq && inq <= copybuf_len)
+		return receive_fallback_to_copy(sk, zc, inq, tss);
+
+	if (inq < PAGE_SIZE) {
+		zc->length = 0;
+		zc->recv_skip_hint = inq;
+		if (!inq && sock_flag(sk, SOCK_DONE))
+			return -EIO;
+		return 0;
+	}
+
+	mmap_read_lock(current->mm);
+
+	vma = vma_lookup(current->mm, address);
+	if (!vma || vma->vm_ops != &tcp_vm_ops) {
+		mmap_read_unlock(current->mm);
+		return -EINVAL;
+	}
+	vma_len = min_t(unsigned long, zc->length, vma->vm_end - address);
+	avail_len = min_t(u32, vma_len, inq);
+	total_bytes_to_map = avail_len & ~(PAGE_SIZE - 1);
+	if (total_bytes_to_map) {
+		if (!(zc->flags & TCP_RECEIVE_ZEROCOPY_FLAG_TLB_CLEAN_HINT))
+			zap_page_range(vma, address, total_bytes_to_map);
+		zc->length = total_bytes_to_map;
+		zc->recv_skip_hint = 0;
+	} else {
+		zc->length = avail_len;
+		zc->recv_skip_hint = avail_len;
+	}
+	ret = 0;
+	while (length + PAGE_SIZE <= zc->length) {
+		int mappable_offset;
+		struct page *page;
+
+		if (zc->recv_skip_hint < PAGE_SIZE) {
+			u32 offset_frag;
+
+			if (skb) {
+				if (zc->recv_skip_hint > 0)
+					break;
+				skb = skb->next;
+				offset = seq - TCP_SKB_CB(skb)->seq;
+			} else {
+				skb = tcp_recv_skb(sk, seq, &offset);
+			}
+
+			if (TCP_SKB_CB(skb)->has_rxtstamp) {
+				tcp_update_recv_tstamps(skb, tss);
+				zc->msg_flags |= TCP_CMSG_TS;
+			}
+			zc->recv_skip_hint = skb->len - offset;
+			frags = skb_advance_to_frag(skb, offset, &offset_frag);
+			if (!frags || offset_frag)
+				break;
+		}
+
+		mappable_offset = find_next_mappable_frag(frags,
+							  zc->recv_skip_hint);
+		if (mappable_offset) {
+			zc->recv_skip_hint = mappable_offset;
+			break;
+		}
+		page = skb_frag_page(frags);
+		prefetchw(page);
+		pages[pages_to_map++] = page;
+		length += PAGE_SIZE;
+		zc->recv_skip_hint -= PAGE_SIZE;
+		frags++;
+		if (pages_to_map == TCP_ZEROCOPY_PAGE_BATCH_SIZE ||
+		    zc->recv_skip_hint < PAGE_SIZE) {
+			/* Either full batch, or we're about to go to next skb
+			 * (and we cannot unroll failed ops across skbs).
+			 */
+			ret = tcp_zerocopy_vm_insert_batch(vma, pages,
+							   pages_to_map,
+							   &address, &length,
+							   &seq, zc,
+							   total_bytes_to_map);
+			if (ret)
+				goto out;
+			pages_to_map = 0;
+		}
+	}
+	if (pages_to_map) {
+		ret = tcp_zerocopy_vm_insert_batch(vma, pages, pages_to_map,
+						   &address, &length, &seq,
+						   zc, total_bytes_to_map);
+	}
+out:
+	mmap_read_unlock(current->mm);
+	/* Try to copy straggler data. */
+	if (!ret)
+		copylen = tcp_zc_handle_leftover(zc, sk, skb, &seq, copybuf_len, tss);
+
+	if (length + copylen) {
+		WRITE_ONCE(tp->copied_seq, seq);
+		tcp_rcv_space_adjust(sk);
+
+		/* Clean up data we have read: This will do ACK frames. */
+		tcp_recv_skb(sk, seq, &offset);
+		tcp_cleanup_rbuf(sk, length + copylen);
+		ret = 0;
+		if (length == zc->length)
+			zc->recv_skip_hint = 0;
+	} else {
+		if (!zc->recv_skip_hint && sock_flag(sk, SOCK_DONE))
+			ret = -EIO;
+	}
+	zc->length = length;
+	return ret;
+}
+#endif
+
+/* Similar to __sock_recv_timestamp, but does not require an skb */
+void tcp_recv_timestamp(struct msghdr *msg, const struct sock *sk,
+			struct scm_timestamping_internal *tss)
+{
+	int new_tstamp = sock_flag(sk, SOCK_TSTAMP_NEW);
+	bool has_timestamping = false;
+
+	if (tss->ts[0].tv_sec || tss->ts[0].tv_nsec) {
+		if (sock_flag(sk, SOCK_RCVTSTAMP)) {
+			if (sock_flag(sk, SOCK_RCVTSTAMPNS)) {
+				if (new_tstamp) {
+					struct __kernel_timespec kts = {
+						.tv_sec = tss->ts[0].tv_sec,
+						.tv_nsec = tss->ts[0].tv_nsec,
+					};
+					put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPNS_NEW,
+						 sizeof(kts), &kts);
+				} else {
+					struct __kernel_old_timespec ts_old = {
+						.tv_sec = tss->ts[0].tv_sec,
+						.tv_nsec = tss->ts[0].tv_nsec,
+					};
+					put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPNS_OLD,
+						 sizeof(ts_old), &ts_old);
+				}
+			} else {
+				if (new_tstamp) {
+					struct __kernel_sock_timeval stv = {
+						.tv_sec = tss->ts[0].tv_sec,
+						.tv_usec = tss->ts[0].tv_nsec / 1000,
+					};
+					put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMP_NEW,
+						 sizeof(stv), &stv);
+				} else {
+					struct __kernel_old_timeval tv = {
+						.tv_sec = tss->ts[0].tv_sec,
+						.tv_usec = tss->ts[0].tv_nsec / 1000,
+					};
+					put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMP_OLD,
+						 sizeof(tv), &tv);
+				}
+			}
+		}
+
+		if (READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_SOFTWARE)
+			has_timestamping = true;
+		else
+			tss->ts[0] = (struct timespec64) {0};
+	}
+
+	if (tss->ts[2].tv_sec || tss->ts[2].tv_nsec) {
+		if (READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_RAW_HARDWARE)
+			has_timestamping = true;
+		else
+			tss->ts[2] = (struct timespec64) {0};
+	}
+
+	if (has_timestamping) {
+		tss->ts[1] = (struct timespec64) {0};
+		if (sock_flag(sk, SOCK_TSTAMP_NEW))
+			put_cmsg_scm_timestamping64(msg, tss);
+		else
+			put_cmsg_scm_timestamping(msg, tss);
+	}
+}
+
+static int tcp_inq_hint(struct sock *sk)
+{
+	const struct tcp_sock *tp = tcp_sk(sk);
+	u32 copied_seq = READ_ONCE(tp->copied_seq);
+	u32 rcv_nxt = READ_ONCE(tp->rcv_nxt);
+	int inq;
+
+	inq = rcv_nxt - copied_seq;
+	if (unlikely(inq < 0 || copied_seq != READ_ONCE(tp->copied_seq))) {
+		lock_sock(sk);
+		inq = tp->rcv_nxt - tp->copied_seq;
+		release_sock(sk);
+	}
+	/* After receiving a FIN, tell the user-space to continue reading
+	 * by returning a non-zero inq.
+	 */
+	if (inq == 0 && sock_flag(sk, SOCK_DONE))
+		inq = 1;
+	return inq;
+}
+
+/*
+ *	This routine copies from a sock struct into the user buffer.
+ *
+ *	Technical note: in 2.3 we work on _locked_ socket, so that
+ *	tricks with *seq access order and skb->users are not required.
+ *	Probably, code can be easily improved even more.
+ */
+
+static int tcp_recvmsg_locked(struct sock *sk, struct msghdr *msg, size_t len,
+			      int flags, struct scm_timestamping_internal *tss,
+			      int *cmsg_flags)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	int copied = 0;
+	u32 peek_seq;
+	u32 *seq;
+	unsigned long used;
+	int err;
+	int target;		/* Read at least this many bytes */
+	long timeo;
+	struct sk_buff *skb, *last;
+	u32 urg_hole = 0;
+
+	err = -ENOTCONN;
+	if (sk->sk_state == TCP_LISTEN)
+		goto out;
+
+	if (tp->recvmsg_inq) {
+		*cmsg_flags = TCP_CMSG_INQ;
+		msg->msg_get_inq = 1;
+	}
+	timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
+
+	/* Urgent data needs to be handled specially. */
+	if (flags & MSG_OOB)
+		goto recv_urg;
+
+	if (unlikely(tp->repair)) {
+		err = -EPERM;
+		if (!(flags & MSG_PEEK))
+			goto out;
+
+		if (tp->repair_queue == TCP_SEND_QUEUE)
+			goto recv_sndq;
+
+		err = -EINVAL;
+		if (tp->repair_queue == TCP_NO_QUEUE)
+			goto out;
+
+		/* 'common' recv queue MSG_PEEK-ing */
+	}
+
+	seq = &tp->copied_seq;
+	if (flags & MSG_PEEK) {
+		peek_seq = tp->copied_seq;
+		seq = &peek_seq;
+	}
+
+	target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
+
+	do {
+		u32 offset;
+
+		/* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
+		if (unlikely(tp->urg_data) && tp->urg_seq == *seq) {
+			if (copied)
+				break;
+			if (signal_pending(current)) {
+				copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
+				break;
+			}
+		}
+
+		/* Next get a buffer. */
+
+		last = skb_peek_tail(&sk->sk_receive_queue);
+		skb_queue_walk(&sk->sk_receive_queue, skb) {
+			last = skb;
+			/* Now that we have two receive queues this
+			 * shouldn't happen.
+			 */
+			if (WARN(before(*seq, TCP_SKB_CB(skb)->seq),
+				 "TCP recvmsg seq # bug: copied %X, seq %X, rcvnxt %X, fl %X\n",
+				 *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt,
+				 flags))
+				break;
+
+			offset = *seq - TCP_SKB_CB(skb)->seq;
+			if (unlikely(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
+				pr_err_once("%s: found a SYN, please report !\n", __func__);
+				offset--;
+			}
+			if (offset < skb->len)
+				goto found_ok_skb;
+			if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
+				goto found_fin_ok;
+			WARN(!(flags & MSG_PEEK),
+			     "TCP recvmsg seq # bug 2: copied %X, seq %X, rcvnxt %X, fl %X\n",
+			     *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt, flags);
+		}
+
+		/* Well, if we have backlog, try to process it now yet. */
+
+		if (copied >= target && !READ_ONCE(sk->sk_backlog.tail))
+			break;
+
+		if (copied) {
+			if (!timeo ||
+			    sk->sk_err ||
+			    sk->sk_state == TCP_CLOSE ||
+			    (sk->sk_shutdown & RCV_SHUTDOWN) ||
+			    signal_pending(current))
+				break;
+		} else {
+			if (sock_flag(sk, SOCK_DONE))
+				break;
+
+			if (sk->sk_err) {
+				copied = sock_error(sk);
+				break;
+			}
+
+			if (sk->sk_shutdown & RCV_SHUTDOWN)
+				break;
+
+			if (sk->sk_state == TCP_CLOSE) {
+				/* This occurs when user tries to read
+				 * from never connected socket.
+				 */
+				copied = -ENOTCONN;
+				break;
+			}
+
+			if (!timeo) {
+				copied = -EAGAIN;
+				break;
+			}
+
+			if (signal_pending(current)) {
+				copied = sock_intr_errno(timeo);
+				break;
+			}
+		}
+
+		if (copied >= target) {
+			/* Do not sleep, just process backlog. */
+			__sk_flush_backlog(sk);
+		} else {
+			tcp_cleanup_rbuf(sk, copied);
+			err = sk_wait_data(sk, &timeo, last);
+			if (err < 0) {
+				err = copied ? : err;
+				goto out;
+			}
+		}
+
+		if ((flags & MSG_PEEK) &&
+		    (peek_seq - copied - urg_hole != tp->copied_seq)) {
+			net_dbg_ratelimited("TCP(%s:%d): Application bug, race in MSG_PEEK\n",
+					    current->comm,
+					    task_pid_nr(current));
+			peek_seq = tp->copied_seq;
+		}
+		continue;
+
+found_ok_skb:
+		/* Ok so how much can we use? */
+		used = skb->len - offset;
+		if (len < used)
+			used = len;
+
+		/* Do we have urgent data here? */
+		if (unlikely(tp->urg_data)) {
+			u32 urg_offset = tp->urg_seq - *seq;
+			if (urg_offset < used) {
+				if (!urg_offset) {
+					if (!sock_flag(sk, SOCK_URGINLINE)) {
+						WRITE_ONCE(*seq, *seq + 1);
+						urg_hole++;
+						offset++;
+						used--;
+						if (!used)
+							goto skip_copy;
+					}
+				} else
+					used = urg_offset;
+			}
+		}
+
+		if (!(flags & MSG_TRUNC)) {
+			err = skb_copy_datagram_msg(skb, offset, msg, used);
+			if (err) {
+				/* Exception. Bailout! */
+				if (!copied)
+					copied = -EFAULT;
+				break;
+			}
+		}
+
+		WRITE_ONCE(*seq, *seq + used);
+		copied += used;
+		len -= used;
+
+		tcp_rcv_space_adjust(sk);
+
+skip_copy:
+		if (unlikely(tp->urg_data) && after(tp->copied_seq, tp->urg_seq)) {
+			WRITE_ONCE(tp->urg_data, 0);
+			tcp_fast_path_check(sk);
+		}
+
+		if (TCP_SKB_CB(skb)->has_rxtstamp) {
+			tcp_update_recv_tstamps(skb, tss);
+			*cmsg_flags |= TCP_CMSG_TS;
+		}
+
+		if (used + offset < skb->len)
+			continue;
+
+		if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
+			goto found_fin_ok;
+		if (!(flags & MSG_PEEK))
+			tcp_eat_recv_skb(sk, skb);
+		continue;
+
+found_fin_ok:
+		/* Process the FIN. */
+		WRITE_ONCE(*seq, *seq + 1);
+		if (!(flags & MSG_PEEK))
+			tcp_eat_recv_skb(sk, skb);
+		break;
+	} while (len > 0);
+
+	/* According to UNIX98, msg_name/msg_namelen are ignored
+	 * on connected socket. I was just happy when found this 8) --ANK
+	 */
+
+	/* Clean up data we have read: This will do ACK frames. */
+	tcp_cleanup_rbuf(sk, copied);
+	return copied;
+
+out:
+	return err;
+
+recv_urg:
+	err = tcp_recv_urg(sk, msg, len, flags);
+	goto out;
+
+recv_sndq:
+	err = tcp_peek_sndq(sk, msg, len);
+	goto out;
+}
+
+int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int flags,
+		int *addr_len)
+{
+	int cmsg_flags = 0, ret;
+	struct scm_timestamping_internal tss;
+
+	if (unlikely(flags & MSG_ERRQUEUE))
+		return inet_recv_error(sk, msg, len, addr_len);
+
+	if (sk_can_busy_loop(sk) &&
+	    skb_queue_empty_lockless(&sk->sk_receive_queue) &&
+	    sk->sk_state == TCP_ESTABLISHED)
+		sk_busy_loop(sk, flags & MSG_DONTWAIT);
+
+	lock_sock(sk);
+	ret = tcp_recvmsg_locked(sk, msg, len, flags, &tss, &cmsg_flags);
+	release_sock(sk);
+
+	if ((cmsg_flags || msg->msg_get_inq) && ret >= 0) {
+		if (cmsg_flags & TCP_CMSG_TS)
+			tcp_recv_timestamp(msg, sk, &tss);
+		if (msg->msg_get_inq) {
+			msg->msg_inq = tcp_inq_hint(sk);
+			if (cmsg_flags & TCP_CMSG_INQ)
+				put_cmsg(msg, SOL_TCP, TCP_CM_INQ,
+					 sizeof(msg->msg_inq), &msg->msg_inq);
+		}
+	}
+	return ret;
+}
+EXPORT_SYMBOL(tcp_recvmsg);
+
+void tcp_set_state(struct sock *sk, int state)
+{
+	int oldstate = sk->sk_state;
+
+	/* We defined a new enum for TCP states that are exported in BPF
+	 * so as not force the internal TCP states to be frozen. The
+	 * following checks will detect if an internal state value ever
+	 * differs from the BPF value. If this ever happens, then we will
+	 * need to remap the internal value to the BPF value before calling
+	 * tcp_call_bpf_2arg.
+	 */
+	BUILD_BUG_ON((int)BPF_TCP_ESTABLISHED != (int)TCP_ESTABLISHED);
+	BUILD_BUG_ON((int)BPF_TCP_SYN_SENT != (int)TCP_SYN_SENT);
+	BUILD_BUG_ON((int)BPF_TCP_SYN_RECV != (int)TCP_SYN_RECV);
+	BUILD_BUG_ON((int)BPF_TCP_FIN_WAIT1 != (int)TCP_FIN_WAIT1);
+	BUILD_BUG_ON((int)BPF_TCP_FIN_WAIT2 != (int)TCP_FIN_WAIT2);
+	BUILD_BUG_ON((int)BPF_TCP_TIME_WAIT != (int)TCP_TIME_WAIT);
+	BUILD_BUG_ON((int)BPF_TCP_CLOSE != (int)TCP_CLOSE);
+	BUILD_BUG_ON((int)BPF_TCP_CLOSE_WAIT != (int)TCP_CLOSE_WAIT);
+	BUILD_BUG_ON((int)BPF_TCP_LAST_ACK != (int)TCP_LAST_ACK);
+	BUILD_BUG_ON((int)BPF_TCP_LISTEN != (int)TCP_LISTEN);
+	BUILD_BUG_ON((int)BPF_TCP_CLOSING != (int)TCP_CLOSING);
+	BUILD_BUG_ON((int)BPF_TCP_NEW_SYN_RECV != (int)TCP_NEW_SYN_RECV);
+	BUILD_BUG_ON((int)BPF_TCP_MAX_STATES != (int)TCP_MAX_STATES);
+
+	/* bpf uapi header bpf.h defines an anonymous enum with values
+	 * BPF_TCP_* used by bpf programs. Currently gcc built vmlinux
+	 * is able to emit this enum in DWARF due to the above BUILD_BUG_ON.
+	 * But clang built vmlinux does not have this enum in DWARF
+	 * since clang removes the above code before generating IR/debuginfo.
+	 * Let us explicitly emit the type debuginfo to ensure the
+	 * above-mentioned anonymous enum in the vmlinux DWARF and hence BTF
+	 * regardless of which compiler is used.
+	 */
+	BTF_TYPE_EMIT_ENUM(BPF_TCP_ESTABLISHED);
+
+	if (BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), BPF_SOCK_OPS_STATE_CB_FLAG))
+		tcp_call_bpf_2arg(sk, BPF_SOCK_OPS_STATE_CB, oldstate, state);
+
+	switch (state) {
+	case TCP_ESTABLISHED:
+		if (oldstate != TCP_ESTABLISHED)
+			TCP_INC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
+		break;
+
+	case TCP_CLOSE:
+		if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED)
+			TCP_INC_STATS(sock_net(sk), TCP_MIB_ESTABRESETS);
+
+		sk->sk_prot->unhash(sk);
+		if (inet_csk(sk)->icsk_bind_hash &&
+		    !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
+			inet_put_port(sk);
+		fallthrough;
+	default:
+		if (oldstate == TCP_ESTABLISHED)
+			TCP_DEC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
+	}
+
+	/* Change state AFTER socket is unhashed to avoid closed
+	 * socket sitting in hash tables.
+	 */
+	inet_sk_state_store(sk, state);
+}
+EXPORT_SYMBOL_GPL(tcp_set_state);
+
+/*
+ *	State processing on a close. This implements the state shift for
+ *	sending our FIN frame. Note that we only send a FIN for some
+ *	states. A shutdown() may have already sent the FIN, or we may be
+ *	closed.
+ */
+
+static const unsigned char new_state[16] = {
+  /* current state:        new state:      action:	*/
+  [0 /* (Invalid) */]	= TCP_CLOSE,
+  [TCP_ESTABLISHED]	= TCP_FIN_WAIT1 | TCP_ACTION_FIN,
+  [TCP_SYN_SENT]	= TCP_CLOSE,
+  [TCP_SYN_RECV]	= TCP_FIN_WAIT1 | TCP_ACTION_FIN,
+  [TCP_FIN_WAIT1]	= TCP_FIN_WAIT1,
+  [TCP_FIN_WAIT2]	= TCP_FIN_WAIT2,
+  [TCP_TIME_WAIT]	= TCP_CLOSE,
+  [TCP_CLOSE]		= TCP_CLOSE,
+  [TCP_CLOSE_WAIT]	= TCP_LAST_ACK  | TCP_ACTION_FIN,
+  [TCP_LAST_ACK]	= TCP_LAST_ACK,
+  [TCP_LISTEN]		= TCP_CLOSE,
+  [TCP_CLOSING]		= TCP_CLOSING,
+  [TCP_NEW_SYN_RECV]	= TCP_CLOSE,	/* should not happen ! */
+};
+
+static int tcp_close_state(struct sock *sk)
+{
+	int next = (int)new_state[sk->sk_state];
+	int ns = next & TCP_STATE_MASK;
+
+	tcp_set_state(sk, ns);
+
+	return next & TCP_ACTION_FIN;
+}
+
+/*
+ *	Shutdown the sending side of a connection. Much like close except
+ *	that we don't receive shut down or sock_set_flag(sk, SOCK_DEAD).
+ */
+
+void tcp_shutdown(struct sock *sk, int how)
+{
+	/*	We need to grab some memory, and put together a FIN,
+	 *	and then put it into the queue to be sent.
+	 *		Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
+	 */
+	if (!(how & SEND_SHUTDOWN))
+		return;
+
+	/* If we've already sent a FIN, or it's a closed state, skip this. */
+	if ((1 << sk->sk_state) &
+	    (TCPF_ESTABLISHED | TCPF_SYN_SENT |
+	     TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
+		/* Clear out any half completed packets.  FIN if needed. */
+		if (tcp_close_state(sk))
+			tcp_send_fin(sk);
+	}
+}
+EXPORT_SYMBOL(tcp_shutdown);
+
+int tcp_orphan_count_sum(void)
+{
+	int i, total = 0;
+
+	for_each_possible_cpu(i)
+		total += per_cpu(tcp_orphan_count, i);
+
+	return max(total, 0);
+}
+
+static int tcp_orphan_cache;
+static struct timer_list tcp_orphan_timer;
+#define TCP_ORPHAN_TIMER_PERIOD msecs_to_jiffies(100)
+
+static void tcp_orphan_update(struct timer_list *unused)
+{
+	WRITE_ONCE(tcp_orphan_cache, tcp_orphan_count_sum());
+	mod_timer(&tcp_orphan_timer, jiffies + TCP_ORPHAN_TIMER_PERIOD);
+}
+
+static bool tcp_too_many_orphans(int shift)
+{
+	return READ_ONCE(tcp_orphan_cache) << shift >
+		READ_ONCE(sysctl_tcp_max_orphans);
+}
+
+bool tcp_check_oom(struct sock *sk, int shift)
+{
+	bool too_many_orphans, out_of_socket_memory;
+
+	too_many_orphans = tcp_too_many_orphans(shift);
+	out_of_socket_memory = tcp_out_of_memory(sk);
+
+	if (too_many_orphans)
+		net_info_ratelimited("too many orphaned sockets\n");
+	if (out_of_socket_memory)
+		net_info_ratelimited("out of memory -- consider tuning tcp_mem\n");
+	return too_many_orphans || out_of_socket_memory;
+}
+
+void __tcp_close(struct sock *sk, long timeout)
+{
+	struct sk_buff *skb;
+	int data_was_unread = 0;
+	int state;
+
+	WRITE_ONCE(sk->sk_shutdown, SHUTDOWN_MASK);
+
+	if (sk->sk_state == TCP_LISTEN) {
+		tcp_set_state(sk, TCP_CLOSE);
+
+		/* Special case. */
+		inet_csk_listen_stop(sk);
+
+		goto adjudge_to_death;
+	}
+
+	/*  We need to flush the recv. buffs.  We do this only on the
+	 *  descriptor close, not protocol-sourced closes, because the
+	 *  reader process may not have drained the data yet!
+	 */
+	while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
+		u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq;
+
+		if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
+			len--;
+		data_was_unread += len;
+		__kfree_skb(skb);
+	}
+
+	/* If socket has been already reset (e.g. in tcp_reset()) - kill it. */
+	if (sk->sk_state == TCP_CLOSE)
+		goto adjudge_to_death;
+
+	/* As outlined in RFC 2525, section 2.17, we send a RST here because
+	 * data was lost. To witness the awful effects of the old behavior of
+	 * always doing a FIN, run an older 2.1.x kernel or 2.0.x, start a bulk
+	 * GET in an FTP client, suspend the process, wait for the client to
+	 * advertise a zero window, then kill -9 the FTP client, wheee...
+	 * Note: timeout is always zero in such a case.
+	 */
+	if (unlikely(tcp_sk(sk)->repair)) {
+		sk->sk_prot->disconnect(sk, 0);
+	} else if (data_was_unread) {
+		/* Unread data was tossed, zap the connection. */
+		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONCLOSE);
+		tcp_set_state(sk, TCP_CLOSE);
+		tcp_send_active_reset(sk, sk->sk_allocation);
+	} else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
+		/* Check zero linger _after_ checking for unread data. */
+		sk->sk_prot->disconnect(sk, 0);
+		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
+	} else if (tcp_close_state(sk)) {
+		/* We FIN if the application ate all the data before
+		 * zapping the connection.
+		 */
+
+		/* RED-PEN. Formally speaking, we have broken TCP state
+		 * machine. State transitions:
+		 *
+		 * TCP_ESTABLISHED -> TCP_FIN_WAIT1
+		 * TCP_SYN_RECV	-> TCP_FIN_WAIT1 (forget it, it's impossible)
+		 * TCP_CLOSE_WAIT -> TCP_LAST_ACK
+		 *
+		 * are legal only when FIN has been sent (i.e. in window),
+		 * rather than queued out of window. Purists blame.
+		 *
+		 * F.e. "RFC state" is ESTABLISHED,
+		 * if Linux state is FIN-WAIT-1, but FIN is still not sent.
+		 *
+		 * The visible declinations are that sometimes
+		 * we enter time-wait state, when it is not required really
+		 * (harmless), do not send active resets, when they are
+		 * required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when
+		 * they look as CLOSING or LAST_ACK for Linux)
+		 * Probably, I missed some more holelets.
+		 * 						--ANK
+		 * XXX (TFO) - To start off we don't support SYN+ACK+FIN
+		 * in a single packet! (May consider it later but will
+		 * probably need API support or TCP_CORK SYN-ACK until
+		 * data is written and socket is closed.)
+		 */
+		tcp_send_fin(sk);
+	}
+
+	sk_stream_wait_close(sk, timeout);
+
+adjudge_to_death:
+	state = sk->sk_state;
+	sock_hold(sk);
+	sock_orphan(sk);
+
+	local_bh_disable();
+	bh_lock_sock(sk);
+	/* remove backlog if any, without releasing ownership. */
+	__release_sock(sk);
+
+	this_cpu_inc(tcp_orphan_count);
+
+	/* Have we already been destroyed by a softirq or backlog? */
+	if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE)
+		goto out;
+
+	/*	This is a (useful) BSD violating of the RFC. There is a
+	 *	problem with TCP as specified in that the other end could
+	 *	keep a socket open forever with no application left this end.
+	 *	We use a 1 minute timeout (about the same as BSD) then kill
+	 *	our end. If they send after that then tough - BUT: long enough
+	 *	that we won't make the old 4*rto = almost no time - whoops
+	 *	reset mistake.
+	 *
+	 *	Nope, it was not mistake. It is really desired behaviour
+	 *	f.e. on http servers, when such sockets are useless, but
+	 *	consume significant resources. Let's do it with special
+	 *	linger2	option.					--ANK
+	 */
+
+	if (sk->sk_state == TCP_FIN_WAIT2) {
+		struct tcp_sock *tp = tcp_sk(sk);
+		if (tp->linger2 < 0) {
+			tcp_set_state(sk, TCP_CLOSE);
+			tcp_send_active_reset(sk, GFP_ATOMIC);
+			__NET_INC_STATS(sock_net(sk),
+					LINUX_MIB_TCPABORTONLINGER);
+		} else {
+			const int tmo = tcp_fin_time(sk);
+
+			if (tmo > TCP_TIMEWAIT_LEN) {
+				inet_csk_reset_keepalive_timer(sk,
+						tmo - TCP_TIMEWAIT_LEN);
+			} else {
+				tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
+				goto out;
+			}
+		}
+	}
+	if (sk->sk_state != TCP_CLOSE) {
+		if (tcp_check_oom(sk, 0)) {
+			tcp_set_state(sk, TCP_CLOSE);
+			tcp_send_active_reset(sk, GFP_ATOMIC);
+			__NET_INC_STATS(sock_net(sk),
+					LINUX_MIB_TCPABORTONMEMORY);
+		} else if (!check_net(sock_net(sk))) {
+			/* Not possible to send reset; just close */
+			tcp_set_state(sk, TCP_CLOSE);
+		}
+	}
+
+	if (sk->sk_state == TCP_CLOSE) {
+		struct request_sock *req;
+
+		req = rcu_dereference_protected(tcp_sk(sk)->fastopen_rsk,
+						lockdep_sock_is_held(sk));
+		/* We could get here with a non-NULL req if the socket is
+		 * aborted (e.g., closed with unread data) before 3WHS
+		 * finishes.
+		 */
+		if (req)
+			reqsk_fastopen_remove(sk, req, false);
+		inet_csk_destroy_sock(sk);
+	}
+	/* Otherwise, socket is reprieved until protocol close. */
+
+out:
+	bh_unlock_sock(sk);
+	local_bh_enable();
+}
+
+void tcp_close(struct sock *sk, long timeout)
+{
+	lock_sock(sk);
+	__tcp_close(sk, timeout);
+	release_sock(sk);
+	sock_put(sk);
+}
+EXPORT_SYMBOL(tcp_close);
+
+/* These states need RST on ABORT according to RFC793 */
+
+static inline bool tcp_need_reset(int state)
+{
+	return (1 << state) &
+	       (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
+		TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
+}
+
+static void tcp_rtx_queue_purge(struct sock *sk)
+{
+	struct rb_node *p = rb_first(&sk->tcp_rtx_queue);
+
+	tcp_sk(sk)->highest_sack = NULL;
+	while (p) {
+		struct sk_buff *skb = rb_to_skb(p);
+
+		p = rb_next(p);
+		/* Since we are deleting whole queue, no need to
+		 * list_del(&skb->tcp_tsorted_anchor)
+		 */
+		tcp_rtx_queue_unlink(skb, sk);
+		tcp_wmem_free_skb(sk, skb);
+	}
+}
+
+void tcp_write_queue_purge(struct sock *sk)
+{
+	struct sk_buff *skb;
+
+	tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
+	while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) {
+		tcp_skb_tsorted_anchor_cleanup(skb);
+		tcp_wmem_free_skb(sk, skb);
+	}
+	tcp_rtx_queue_purge(sk);
+	INIT_LIST_HEAD(&tcp_sk(sk)->tsorted_sent_queue);
+	tcp_clear_all_retrans_hints(tcp_sk(sk));
+	tcp_sk(sk)->packets_out = 0;
+	inet_csk(sk)->icsk_backoff = 0;
+}
+
+int tcp_disconnect(struct sock *sk, int flags)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	struct inet_connection_sock *icsk = inet_csk(sk);
+	struct tcp_sock *tp = tcp_sk(sk);
+	int old_state = sk->sk_state;
+	u32 seq;
+
+	if (old_state != TCP_CLOSE)
+		tcp_set_state(sk, TCP_CLOSE);
+
+	/* ABORT function of RFC793 */
+	if (old_state == TCP_LISTEN) {
+		inet_csk_listen_stop(sk);
+	} else if (unlikely(tp->repair)) {
+		sk->sk_err = ECONNABORTED;
+	} else if (tcp_need_reset(old_state) ||
+		   (tp->snd_nxt != tp->write_seq &&
+		    (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
+		/* The last check adjusts for discrepancy of Linux wrt. RFC
+		 * states
+		 */
+		tcp_send_active_reset(sk, gfp_any());
+		sk->sk_err = ECONNRESET;
+	} else if (old_state == TCP_SYN_SENT)
+		sk->sk_err = ECONNRESET;
+
+	tcp_clear_xmit_timers(sk);
+	__skb_queue_purge(&sk->sk_receive_queue);
+	WRITE_ONCE(tp->copied_seq, tp->rcv_nxt);
+	WRITE_ONCE(tp->urg_data, 0);
+	tcp_write_queue_purge(sk);
+	tcp_fastopen_active_disable_ofo_check(sk);
+	skb_rbtree_purge(&tp->out_of_order_queue);
+
+	inet->inet_dport = 0;
+
+	inet_bhash2_reset_saddr(sk);
+
+	WRITE_ONCE(sk->sk_shutdown, 0);
+	sock_reset_flag(sk, SOCK_DONE);
+	tp->srtt_us = 0;
+	tp->mdev_us = jiffies_to_usecs(TCP_TIMEOUT_INIT);
+	tp->rcv_rtt_last_tsecr = 0;
+
+	seq = tp->write_seq + tp->max_window + 2;
+	if (!seq)
+		seq = 1;
+	WRITE_ONCE(tp->write_seq, seq);
+
+	icsk->icsk_backoff = 0;
+	icsk->icsk_probes_out = 0;
+	icsk->icsk_probes_tstamp = 0;
+	icsk->icsk_rto = TCP_TIMEOUT_INIT;
+	icsk->icsk_rto_min = TCP_RTO_MIN;
+	icsk->icsk_delack_max = TCP_DELACK_MAX;
+	tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
+	tcp_snd_cwnd_set(tp, TCP_INIT_CWND);
+	tp->snd_cwnd_cnt = 0;
+	tp->is_cwnd_limited = 0;
+	tp->max_packets_out = 0;
+	tp->window_clamp = 0;
+	tp->delivered = 0;
+	tp->delivered_ce = 0;
+	if (icsk->icsk_ca_ops->release)
+		icsk->icsk_ca_ops->release(sk);
+	memset(icsk->icsk_ca_priv, 0, sizeof(icsk->icsk_ca_priv));
+	icsk->icsk_ca_initialized = 0;
+	tcp_set_ca_state(sk, TCP_CA_Open);
+	tp->is_sack_reneg = 0;
+	tcp_clear_retrans(tp);
+	tp->total_retrans = 0;
+	inet_csk_delack_init(sk);
+	/* Initialize rcv_mss to TCP_MIN_MSS to avoid division by 0
+	 * issue in __tcp_select_window()
+	 */
+	icsk->icsk_ack.rcv_mss = TCP_MIN_MSS;
+	memset(&tp->rx_opt, 0, sizeof(tp->rx_opt));
+	__sk_dst_reset(sk);
+	dst_release(xchg((__force struct dst_entry **)&sk->sk_rx_dst, NULL));
+	tcp_saved_syn_free(tp);
+	tp->compressed_ack = 0;
+	tp->segs_in = 0;
+	tp->segs_out = 0;
+	tp->bytes_sent = 0;
+	tp->bytes_acked = 0;
+	tp->bytes_received = 0;
+	tp->bytes_retrans = 0;
+	tp->data_segs_in = 0;
+	tp->data_segs_out = 0;
+	tp->duplicate_sack[0].start_seq = 0;
+	tp->duplicate_sack[0].end_seq = 0;
+	tp->dsack_dups = 0;
+	tp->reord_seen = 0;
+	tp->retrans_out = 0;
+	tp->sacked_out = 0;
+	tp->tlp_high_seq = 0;
+	tp->last_oow_ack_time = 0;
+	/* There's a bubble in the pipe until at least the first ACK. */
+	tp->app_limited = ~0U;
+	tp->rate_app_limited = 1;
+	tp->rack.mstamp = 0;
+	tp->rack.advanced = 0;
+	tp->rack.reo_wnd_steps = 1;
+	tp->rack.last_delivered = 0;
+	tp->rack.reo_wnd_persist = 0;
+	tp->rack.dsack_seen = 0;
+	tp->syn_data_acked = 0;
+	tp->rx_opt.saw_tstamp = 0;
+	tp->rx_opt.dsack = 0;
+	tp->rx_opt.num_sacks = 0;
+	tp->rcv_ooopack = 0;
+
+
+	/* Clean up fastopen related fields */
+	tcp_free_fastopen_req(tp);
+	inet->defer_connect = 0;
+	tp->fastopen_client_fail = 0;
+
+	WARN_ON(inet->inet_num && !icsk->icsk_bind_hash);
+
+	if (sk->sk_frag.page) {
+		put_page(sk->sk_frag.page);
+		sk->sk_frag.page = NULL;
+		sk->sk_frag.offset = 0;
+	}
+	sk_error_report(sk);
+	return 0;
+}
+EXPORT_SYMBOL(tcp_disconnect);
+
+static inline bool tcp_can_repair_sock(const struct sock *sk)
+{
+	return sockopt_ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN) &&
+		(sk->sk_state != TCP_LISTEN);
+}
+
+static int tcp_repair_set_window(struct tcp_sock *tp, sockptr_t optbuf, int len)
+{
+	struct tcp_repair_window opt;
+
+	if (!tp->repair)
+		return -EPERM;
+
+	if (len != sizeof(opt))
+		return -EINVAL;
+
+	if (copy_from_sockptr(&opt, optbuf, sizeof(opt)))
+		return -EFAULT;
+
+	if (opt.max_window < opt.snd_wnd)
+		return -EINVAL;
+
+	if (after(opt.snd_wl1, tp->rcv_nxt + opt.rcv_wnd))
+		return -EINVAL;
+
+	if (after(opt.rcv_wup, tp->rcv_nxt))
+		return -EINVAL;
+
+	tp->snd_wl1	= opt.snd_wl1;
+	tp->snd_wnd	= opt.snd_wnd;
+	tp->max_window	= opt.max_window;
+
+	tp->rcv_wnd	= opt.rcv_wnd;
+	tp->rcv_wup	= opt.rcv_wup;
+
+	return 0;
+}
+
+static int tcp_repair_options_est(struct sock *sk, sockptr_t optbuf,
+		unsigned int len)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct tcp_repair_opt opt;
+	size_t offset = 0;
+
+	while (len >= sizeof(opt)) {
+		if (copy_from_sockptr_offset(&opt, optbuf, offset, sizeof(opt)))
+			return -EFAULT;
+
+		offset += sizeof(opt);
+		len -= sizeof(opt);
+
+		switch (opt.opt_code) {
+		case TCPOPT_MSS:
+			tp->rx_opt.mss_clamp = opt.opt_val;
+			tcp_mtup_init(sk);
+			break;
+		case TCPOPT_WINDOW:
+			{
+				u16 snd_wscale = opt.opt_val & 0xFFFF;
+				u16 rcv_wscale = opt.opt_val >> 16;
+
+				if (snd_wscale > TCP_MAX_WSCALE || rcv_wscale > TCP_MAX_WSCALE)
+					return -EFBIG;
+
+				tp->rx_opt.snd_wscale = snd_wscale;
+				tp->rx_opt.rcv_wscale = rcv_wscale;
+				tp->rx_opt.wscale_ok = 1;
+			}
+			break;
+		case TCPOPT_SACK_PERM:
+			if (opt.opt_val != 0)
+				return -EINVAL;
+
+			tp->rx_opt.sack_ok |= TCP_SACK_SEEN;
+			break;
+		case TCPOPT_TIMESTAMP:
+			if (opt.opt_val != 0)
+				return -EINVAL;
+
+			tp->rx_opt.tstamp_ok = 1;
+			break;
+		}
+	}
+
+	return 0;
+}
+
+DEFINE_STATIC_KEY_FALSE(tcp_tx_delay_enabled);
+EXPORT_SYMBOL(tcp_tx_delay_enabled);
+
+static void tcp_enable_tx_delay(void)
+{
+	if (!static_branch_unlikely(&tcp_tx_delay_enabled)) {
+		static int __tcp_tx_delay_enabled = 0;
+
+		if (cmpxchg(&__tcp_tx_delay_enabled, 0, 1) == 0) {
+			static_branch_enable(&tcp_tx_delay_enabled);
+			pr_info("TCP_TX_DELAY enabled\n");
+		}
+	}
+}
+
+/* When set indicates to always queue non-full frames.  Later the user clears
+ * this option and we transmit any pending partial frames in the queue.  This is
+ * meant to be used alongside sendfile() to get properly filled frames when the
+ * user (for example) must write out headers with a write() call first and then
+ * use sendfile to send out the data parts.
+ *
+ * TCP_CORK can be set together with TCP_NODELAY and it is stronger than
+ * TCP_NODELAY.
+ */
+void __tcp_sock_set_cork(struct sock *sk, bool on)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	if (on) {
+		tp->nonagle |= TCP_NAGLE_CORK;
+	} else {
+		tp->nonagle &= ~TCP_NAGLE_CORK;
+		if (tp->nonagle & TCP_NAGLE_OFF)
+			tp->nonagle |= TCP_NAGLE_PUSH;
+		tcp_push_pending_frames(sk);
+	}
+}
+
+void tcp_sock_set_cork(struct sock *sk, bool on)
+{
+	lock_sock(sk);
+	__tcp_sock_set_cork(sk, on);
+	release_sock(sk);
+}
+EXPORT_SYMBOL(tcp_sock_set_cork);
+
+/* TCP_NODELAY is weaker than TCP_CORK, so that this option on corked socket is
+ * remembered, but it is not activated until cork is cleared.
+ *
+ * However, when TCP_NODELAY is set we make an explicit push, which overrides
+ * even TCP_CORK for currently queued segments.
+ */
+void __tcp_sock_set_nodelay(struct sock *sk, bool on)
+{
+	if (on) {
+		tcp_sk(sk)->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH;
+		tcp_push_pending_frames(sk);
+	} else {
+		tcp_sk(sk)->nonagle &= ~TCP_NAGLE_OFF;
+	}
+}
+
+void tcp_sock_set_nodelay(struct sock *sk)
+{
+	lock_sock(sk);
+	__tcp_sock_set_nodelay(sk, true);
+	release_sock(sk);
+}
+EXPORT_SYMBOL(tcp_sock_set_nodelay);
+
+static void __tcp_sock_set_quickack(struct sock *sk, int val)
+{
+	if (!val) {
+		inet_csk_enter_pingpong_mode(sk);
+		return;
+	}
+
+	inet_csk_exit_pingpong_mode(sk);
+	if ((1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
+	    inet_csk_ack_scheduled(sk)) {
+		inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_PUSHED;
+		tcp_cleanup_rbuf(sk, 1);
+		if (!(val & 1))
+			inet_csk_enter_pingpong_mode(sk);
+	}
+}
+
+void tcp_sock_set_quickack(struct sock *sk, int val)
+{
+	lock_sock(sk);
+	__tcp_sock_set_quickack(sk, val);
+	release_sock(sk);
+}
+EXPORT_SYMBOL(tcp_sock_set_quickack);
+
+int tcp_sock_set_syncnt(struct sock *sk, int val)
+{
+	if (val < 1 || val > MAX_TCP_SYNCNT)
+		return -EINVAL;
+
+	lock_sock(sk);
+	WRITE_ONCE(inet_csk(sk)->icsk_syn_retries, val);
+	release_sock(sk);
+	return 0;
+}
+EXPORT_SYMBOL(tcp_sock_set_syncnt);
+
+void tcp_sock_set_user_timeout(struct sock *sk, u32 val)
+{
+	lock_sock(sk);
+	WRITE_ONCE(inet_csk(sk)->icsk_user_timeout, val);
+	release_sock(sk);
+}
+EXPORT_SYMBOL(tcp_sock_set_user_timeout);
+
+int tcp_sock_set_keepidle_locked(struct sock *sk, int val)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	if (val < 1 || val > MAX_TCP_KEEPIDLE)
+		return -EINVAL;
+
+	/* Paired with WRITE_ONCE() in keepalive_time_when() */
+	WRITE_ONCE(tp->keepalive_time, val * HZ);
+	if (sock_flag(sk, SOCK_KEEPOPEN) &&
+	    !((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))) {
+		u32 elapsed = keepalive_time_elapsed(tp);
+
+		if (tp->keepalive_time > elapsed)
+			elapsed = tp->keepalive_time - elapsed;
+		else
+			elapsed = 0;
+		inet_csk_reset_keepalive_timer(sk, elapsed);
+	}
+
+	return 0;
+}
+
+int tcp_sock_set_keepidle(struct sock *sk, int val)
+{
+	int err;
+
+	lock_sock(sk);
+	err = tcp_sock_set_keepidle_locked(sk, val);
+	release_sock(sk);
+	return err;
+}
+EXPORT_SYMBOL(tcp_sock_set_keepidle);
+
+int tcp_sock_set_keepintvl(struct sock *sk, int val)
+{
+	if (val < 1 || val > MAX_TCP_KEEPINTVL)
+		return -EINVAL;
+
+	lock_sock(sk);
+	WRITE_ONCE(tcp_sk(sk)->keepalive_intvl, val * HZ);
+	release_sock(sk);
+	return 0;
+}
+EXPORT_SYMBOL(tcp_sock_set_keepintvl);
+
+int tcp_sock_set_keepcnt(struct sock *sk, int val)
+{
+	if (val < 1 || val > MAX_TCP_KEEPCNT)
+		return -EINVAL;
+
+	lock_sock(sk);
+	/* Paired with READ_ONCE() in keepalive_probes() */
+	WRITE_ONCE(tcp_sk(sk)->keepalive_probes, val);
+	release_sock(sk);
+	return 0;
+}
+EXPORT_SYMBOL(tcp_sock_set_keepcnt);
+
+int tcp_set_window_clamp(struct sock *sk, int val)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	if (!val) {
+		if (sk->sk_state != TCP_CLOSE)
+			return -EINVAL;
+		tp->window_clamp = 0;
+	} else {
+		u32 new_rcv_ssthresh, old_window_clamp = tp->window_clamp;
+		u32 new_window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
+						SOCK_MIN_RCVBUF / 2 : val;
+
+		if (new_window_clamp == old_window_clamp)
+			return 0;
+
+		tp->window_clamp = new_window_clamp;
+		if (new_window_clamp < old_window_clamp) {
+			/* need to apply the reserved mem provisioning only
+			 * when shrinking the window clamp
+			 */
+			__tcp_adjust_rcv_ssthresh(sk, tp->window_clamp);
+
+		} else {
+			new_rcv_ssthresh = min(tp->rcv_wnd, tp->window_clamp);
+			tp->rcv_ssthresh = max(new_rcv_ssthresh,
+					       tp->rcv_ssthresh);
+		}
+	}
+	return 0;
+}
+
+/*
+ *	Socket option code for TCP.
+ */
+int do_tcp_setsockopt(struct sock *sk, int level, int optname,
+		      sockptr_t optval, unsigned int optlen)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct inet_connection_sock *icsk = inet_csk(sk);
+	struct net *net = sock_net(sk);
+	int val;
+	int err = 0;
+
+	/* These are data/string values, all the others are ints */
+	switch (optname) {
+	case TCP_CONGESTION: {
+		char name[TCP_CA_NAME_MAX];
+
+		if (optlen < 1)
+			return -EINVAL;
+
+		val = strncpy_from_sockptr(name, optval,
+					min_t(long, TCP_CA_NAME_MAX-1, optlen));
+		if (val < 0)
+			return -EFAULT;
+		name[val] = 0;
+
+		sockopt_lock_sock(sk);
+		err = tcp_set_congestion_control(sk, name, !has_current_bpf_ctx(),
+						 sockopt_ns_capable(sock_net(sk)->user_ns,
+								    CAP_NET_ADMIN));
+		sockopt_release_sock(sk);
+		return err;
+	}
+	case TCP_ULP: {
+		char name[TCP_ULP_NAME_MAX];
+
+		if (optlen < 1)
+			return -EINVAL;
+
+		val = strncpy_from_sockptr(name, optval,
+					min_t(long, TCP_ULP_NAME_MAX - 1,
+					      optlen));
+		if (val < 0)
+			return -EFAULT;
+		name[val] = 0;
+
+		sockopt_lock_sock(sk);
+		err = tcp_set_ulp(sk, name);
+		sockopt_release_sock(sk);
+		return err;
+	}
+	case TCP_FASTOPEN_KEY: {
+		__u8 key[TCP_FASTOPEN_KEY_BUF_LENGTH];
+		__u8 *backup_key = NULL;
+
+		/* Allow a backup key as well to facilitate key rotation
+		 * First key is the active one.
+		 */
+		if (optlen != TCP_FASTOPEN_KEY_LENGTH &&
+		    optlen != TCP_FASTOPEN_KEY_BUF_LENGTH)
+			return -EINVAL;
+
+		if (copy_from_sockptr(key, optval, optlen))
+			return -EFAULT;
+
+		if (optlen == TCP_FASTOPEN_KEY_BUF_LENGTH)
+			backup_key = key + TCP_FASTOPEN_KEY_LENGTH;
+
+		return tcp_fastopen_reset_cipher(net, sk, key, backup_key);
+	}
+	default:
+		/* fallthru */
+		break;
+	}
+
+	if (optlen < sizeof(int))
+		return -EINVAL;
+
+	if (copy_from_sockptr(&val, optval, sizeof(val)))
+		return -EFAULT;
+
+	sockopt_lock_sock(sk);
+
+	switch (optname) {
+	case TCP_MAXSEG:
+		/* Values greater than interface MTU won't take effect. However
+		 * at the point when this call is done we typically don't yet
+		 * know which interface is going to be used
+		 */
+		if (val && (val < TCP_MIN_MSS || val > MAX_TCP_WINDOW)) {
+			err = -EINVAL;
+			break;
+		}
+		tp->rx_opt.user_mss = val;
+		break;
+
+	case TCP_NODELAY:
+		__tcp_sock_set_nodelay(sk, val);
+		break;
+
+	case TCP_THIN_LINEAR_TIMEOUTS:
+		if (val < 0 || val > 1)
+			err = -EINVAL;
+		else
+			tp->thin_lto = val;
+		break;
+
+	case TCP_THIN_DUPACK:
+		if (val < 0 || val > 1)
+			err = -EINVAL;
+		break;
+
+	case TCP_REPAIR:
+		if (!tcp_can_repair_sock(sk))
+			err = -EPERM;
+		else if (val == TCP_REPAIR_ON) {
+			tp->repair = 1;
+			sk->sk_reuse = SK_FORCE_REUSE;
+			tp->repair_queue = TCP_NO_QUEUE;
+		} else if (val == TCP_REPAIR_OFF) {
+			tp->repair = 0;
+			sk->sk_reuse = SK_NO_REUSE;
+			tcp_send_window_probe(sk);
+		} else if (val == TCP_REPAIR_OFF_NO_WP) {
+			tp->repair = 0;
+			sk->sk_reuse = SK_NO_REUSE;
+		} else
+			err = -EINVAL;
+
+		break;
+
+	case TCP_REPAIR_QUEUE:
+		if (!tp->repair)
+			err = -EPERM;
+		else if ((unsigned int)val < TCP_QUEUES_NR)
+			tp->repair_queue = val;
+		else
+			err = -EINVAL;
+		break;
+
+	case TCP_QUEUE_SEQ:
+		if (sk->sk_state != TCP_CLOSE) {
+			err = -EPERM;
+		} else if (tp->repair_queue == TCP_SEND_QUEUE) {
+			if (!tcp_rtx_queue_empty(sk))
+				err = -EPERM;
+			else
+				WRITE_ONCE(tp->write_seq, val);
+		} else if (tp->repair_queue == TCP_RECV_QUEUE) {
+			if (tp->rcv_nxt != tp->copied_seq) {
+				err = -EPERM;
+			} else {
+				WRITE_ONCE(tp->rcv_nxt, val);
+				WRITE_ONCE(tp->copied_seq, val);
+			}
+		} else {
+			err = -EINVAL;
+		}
+		break;
+
+	case TCP_REPAIR_OPTIONS:
+		if (!tp->repair)
+			err = -EINVAL;
+		else if (sk->sk_state == TCP_ESTABLISHED && !tp->bytes_sent)
+			err = tcp_repair_options_est(sk, optval, optlen);
+		else
+			err = -EPERM;
+		break;
+
+	case TCP_CORK:
+		__tcp_sock_set_cork(sk, val);
+		break;
+
+	case TCP_KEEPIDLE:
+		err = tcp_sock_set_keepidle_locked(sk, val);
+		break;
+	case TCP_KEEPINTVL:
+		if (val < 1 || val > MAX_TCP_KEEPINTVL)
+			err = -EINVAL;
+		else
+			WRITE_ONCE(tp->keepalive_intvl, val * HZ);
+		break;
+	case TCP_KEEPCNT:
+		if (val < 1 || val > MAX_TCP_KEEPCNT)
+			err = -EINVAL;
+		else
+			WRITE_ONCE(tp->keepalive_probes, val);
+		break;
+	case TCP_SYNCNT:
+		if (val < 1 || val > MAX_TCP_SYNCNT)
+			err = -EINVAL;
+		else
+			WRITE_ONCE(icsk->icsk_syn_retries, val);
+		break;
+
+	case TCP_SAVE_SYN:
+		/* 0: disable, 1: enable, 2: start from ether_header */
+		if (val < 0 || val > 2)
+			err = -EINVAL;
+		else
+			tp->save_syn = val;
+		break;
+
+	case TCP_LINGER2:
+		if (val < 0)
+			WRITE_ONCE(tp->linger2, -1);
+		else if (val > TCP_FIN_TIMEOUT_MAX / HZ)
+			WRITE_ONCE(tp->linger2, TCP_FIN_TIMEOUT_MAX);
+		else
+			WRITE_ONCE(tp->linger2, val * HZ);
+		break;
+
+	case TCP_DEFER_ACCEPT:
+		/* Translate value in seconds to number of retransmits */
+		WRITE_ONCE(icsk->icsk_accept_queue.rskq_defer_accept,
+			   secs_to_retrans(val, TCP_TIMEOUT_INIT / HZ,
+					   TCP_RTO_MAX / HZ));
+		break;
+
+	case TCP_WINDOW_CLAMP:
+		err = tcp_set_window_clamp(sk, val);
+		break;
+
+	case TCP_QUICKACK:
+		__tcp_sock_set_quickack(sk, val);
+		break;
+
+#ifdef CONFIG_TCP_MD5SIG
+	case TCP_MD5SIG:
+	case TCP_MD5SIG_EXT:
+		err = tp->af_specific->md5_parse(sk, optname, optval, optlen);
+		break;
+#endif
+	case TCP_USER_TIMEOUT:
+		/* Cap the max time in ms TCP will retry or probe the window
+		 * before giving up and aborting (ETIMEDOUT) a connection.
+		 */
+		if (val < 0)
+			err = -EINVAL;
+		else
+			WRITE_ONCE(icsk->icsk_user_timeout, val);
+		break;
+
+	case TCP_FASTOPEN:
+		if (val >= 0 && ((1 << sk->sk_state) & (TCPF_CLOSE |
+		    TCPF_LISTEN))) {
+			tcp_fastopen_init_key_once(net);
+
+			fastopen_queue_tune(sk, val);
+		} else {
+			err = -EINVAL;
+		}
+		break;
+	case TCP_FASTOPEN_CONNECT:
+		if (val > 1 || val < 0) {
+			err = -EINVAL;
+		} else if (READ_ONCE(net->ipv4.sysctl_tcp_fastopen) &
+			   TFO_CLIENT_ENABLE) {
+			if (sk->sk_state == TCP_CLOSE)
+				tp->fastopen_connect = val;
+			else
+				err = -EINVAL;
+		} else {
+			err = -EOPNOTSUPP;
+		}
+		break;
+	case TCP_FASTOPEN_NO_COOKIE:
+		if (val > 1 || val < 0)
+			err = -EINVAL;
+		else if (!((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
+			err = -EINVAL;
+		else
+			tp->fastopen_no_cookie = val;
+		break;
+	case TCP_TIMESTAMP:
+		if (!tp->repair)
+			err = -EPERM;
+		else
+			WRITE_ONCE(tp->tsoffset, val - tcp_time_stamp_raw());
+		break;
+	case TCP_REPAIR_WINDOW:
+		err = tcp_repair_set_window(tp, optval, optlen);
+		break;
+	case TCP_NOTSENT_LOWAT:
+		WRITE_ONCE(tp->notsent_lowat, val);
+		sk->sk_write_space(sk);
+		break;
+	case TCP_INQ:
+		if (val > 1 || val < 0)
+			err = -EINVAL;
+		else
+			tp->recvmsg_inq = val;
+		break;
+	case TCP_TX_DELAY:
+		if (val)
+			tcp_enable_tx_delay();
+		WRITE_ONCE(tp->tcp_tx_delay, val);
+		break;
+	default:
+		err = -ENOPROTOOPT;
+		break;
+	}
+
+	sockopt_release_sock(sk);
+	return err;
+}
+
+int tcp_setsockopt(struct sock *sk, int level, int optname, sockptr_t optval,
+		   unsigned int optlen)
+{
+	const struct inet_connection_sock *icsk = inet_csk(sk);
+
+	if (level != SOL_TCP)
+		/* Paired with WRITE_ONCE() in do_ipv6_setsockopt() and tcp_v6_connect() */
+		return READ_ONCE(icsk->icsk_af_ops)->setsockopt(sk, level, optname,
+								optval, optlen);
+	return do_tcp_setsockopt(sk, level, optname, optval, optlen);
+}
+EXPORT_SYMBOL(tcp_setsockopt);
+
+static void tcp_get_info_chrono_stats(const struct tcp_sock *tp,
+				      struct tcp_info *info)
+{
+	u64 stats[__TCP_CHRONO_MAX], total = 0;
+	enum tcp_chrono i;
+
+	for (i = TCP_CHRONO_BUSY; i < __TCP_CHRONO_MAX; ++i) {
+		stats[i] = tp->chrono_stat[i - 1];
+		if (i == tp->chrono_type)
+			stats[i] += tcp_jiffies32 - tp->chrono_start;
+		stats[i] *= USEC_PER_SEC / HZ;
+		total += stats[i];
+	}
+
+	info->tcpi_busy_time = total;
+	info->tcpi_rwnd_limited = stats[TCP_CHRONO_RWND_LIMITED];
+	info->tcpi_sndbuf_limited = stats[TCP_CHRONO_SNDBUF_LIMITED];
+}
+
+/* Return information about state of tcp endpoint in API format. */
+void tcp_get_info(struct sock *sk, struct tcp_info *info)
+{
+	const struct tcp_sock *tp = tcp_sk(sk); /* iff sk_type == SOCK_STREAM */
+	const struct inet_connection_sock *icsk = inet_csk(sk);
+	unsigned long rate;
+	u32 now;
+	u64 rate64;
+	bool slow;
+
+	memset(info, 0, sizeof(*info));
+	if (sk->sk_type != SOCK_STREAM)
+		return;
+
+	info->tcpi_state = inet_sk_state_load(sk);
+
+	/* Report meaningful fields for all TCP states, including listeners */
+	rate = READ_ONCE(sk->sk_pacing_rate);
+	rate64 = (rate != ~0UL) ? rate : ~0ULL;
+	info->tcpi_pacing_rate = rate64;
+
+	rate = READ_ONCE(sk->sk_max_pacing_rate);
+	rate64 = (rate != ~0UL) ? rate : ~0ULL;
+	info->tcpi_max_pacing_rate = rate64;
+
+	info->tcpi_reordering = tp->reordering;
+	info->tcpi_snd_cwnd = tcp_snd_cwnd(tp);
+
+	if (info->tcpi_state == TCP_LISTEN) {
+		/* listeners aliased fields :
+		 * tcpi_unacked -> Number of children ready for accept()
+		 * tcpi_sacked  -> max backlog
+		 */
+		info->tcpi_unacked = READ_ONCE(sk->sk_ack_backlog);
+		info->tcpi_sacked = READ_ONCE(sk->sk_max_ack_backlog);
+		return;
+	}
+
+	slow = lock_sock_fast(sk);
+
+	info->tcpi_ca_state = icsk->icsk_ca_state;
+	info->tcpi_retransmits = icsk->icsk_retransmits;
+	info->tcpi_probes = icsk->icsk_probes_out;
+	info->tcpi_backoff = icsk->icsk_backoff;
+
+	if (tp->rx_opt.tstamp_ok)
+		info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
+	if (tcp_is_sack(tp))
+		info->tcpi_options |= TCPI_OPT_SACK;
+	if (tp->rx_opt.wscale_ok) {
+		info->tcpi_options |= TCPI_OPT_WSCALE;
+		info->tcpi_snd_wscale = tp->rx_opt.snd_wscale;
+		info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
+	}
+
+	if (tp->ecn_flags & TCP_ECN_OK)
+		info->tcpi_options |= TCPI_OPT_ECN;
+	if (tp->ecn_flags & TCP_ECN_SEEN)
+		info->tcpi_options |= TCPI_OPT_ECN_SEEN;
+	if (tp->syn_data_acked)
+		info->tcpi_options |= TCPI_OPT_SYN_DATA;
+
+	info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
+	info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);
+	info->tcpi_snd_mss = tp->mss_cache;
+	info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;
+
+	info->tcpi_unacked = tp->packets_out;
+	info->tcpi_sacked = tp->sacked_out;
+
+	info->tcpi_lost = tp->lost_out;
+	info->tcpi_retrans = tp->retrans_out;
+
+	now = tcp_jiffies32;
+	info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
+	info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
+	info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);
+
+	info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
+	info->tcpi_rcv_ssthresh = tp->rcv_ssthresh;
+	info->tcpi_rtt = tp->srtt_us >> 3;
+	info->tcpi_rttvar = tp->mdev_us >> 2;
+	info->tcpi_snd_ssthresh = tp->snd_ssthresh;
+	info->tcpi_advmss = tp->advmss;
+
+	info->tcpi_rcv_rtt = tp->rcv_rtt_est.rtt_us >> 3;
+	info->tcpi_rcv_space = tp->rcvq_space.space;
+
+	info->tcpi_total_retrans = tp->total_retrans;
+
+	info->tcpi_bytes_acked = tp->bytes_acked;
+	info->tcpi_bytes_received = tp->bytes_received;
+	info->tcpi_notsent_bytes = max_t(int, 0, tp->write_seq - tp->snd_nxt);
+	tcp_get_info_chrono_stats(tp, info);
+
+	info->tcpi_segs_out = tp->segs_out;
+
+	/* segs_in and data_segs_in can be updated from tcp_segs_in() from BH */
+	info->tcpi_segs_in = READ_ONCE(tp->segs_in);
+	info->tcpi_data_segs_in = READ_ONCE(tp->data_segs_in);
+
+	info->tcpi_min_rtt = tcp_min_rtt(tp);
+	info->tcpi_data_segs_out = tp->data_segs_out;
+
+	info->tcpi_delivery_rate_app_limited = tp->rate_app_limited ? 1 : 0;
+	rate64 = tcp_compute_delivery_rate(tp);
+	if (rate64)
+		info->tcpi_delivery_rate = rate64;
+	info->tcpi_delivered = tp->delivered;
+	info->tcpi_delivered_ce = tp->delivered_ce;
+	info->tcpi_bytes_sent = tp->bytes_sent;
+	info->tcpi_bytes_retrans = tp->bytes_retrans;
+	info->tcpi_dsack_dups = tp->dsack_dups;
+	info->tcpi_reord_seen = tp->reord_seen;
+	info->tcpi_rcv_ooopack = tp->rcv_ooopack;
+	info->tcpi_snd_wnd = tp->snd_wnd;
+	info->tcpi_fastopen_client_fail = tp->fastopen_client_fail;
+	unlock_sock_fast(sk, slow);
+}
+EXPORT_SYMBOL_GPL(tcp_get_info);
+
+static size_t tcp_opt_stats_get_size(void)
+{
+	return
+		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_BUSY */
+		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_RWND_LIMITED */
+		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_SNDBUF_LIMITED */
+		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_DATA_SEGS_OUT */
+		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_TOTAL_RETRANS */
+		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_PACING_RATE */
+		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_DELIVERY_RATE */
+		nla_total_size(sizeof(u32)) + /* TCP_NLA_SND_CWND */
+		nla_total_size(sizeof(u32)) + /* TCP_NLA_REORDERING */
+		nla_total_size(sizeof(u32)) + /* TCP_NLA_MIN_RTT */
+		nla_total_size(sizeof(u8)) + /* TCP_NLA_RECUR_RETRANS */
+		nla_total_size(sizeof(u8)) + /* TCP_NLA_DELIVERY_RATE_APP_LMT */
+		nla_total_size(sizeof(u32)) + /* TCP_NLA_SNDQ_SIZE */
+		nla_total_size(sizeof(u8)) + /* TCP_NLA_CA_STATE */
+		nla_total_size(sizeof(u32)) + /* TCP_NLA_SND_SSTHRESH */
+		nla_total_size(sizeof(u32)) + /* TCP_NLA_DELIVERED */
+		nla_total_size(sizeof(u32)) + /* TCP_NLA_DELIVERED_CE */
+		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_BYTES_SENT */
+		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_BYTES_RETRANS */
+		nla_total_size(sizeof(u32)) + /* TCP_NLA_DSACK_DUPS */
+		nla_total_size(sizeof(u32)) + /* TCP_NLA_REORD_SEEN */
+		nla_total_size(sizeof(u32)) + /* TCP_NLA_SRTT */
+		nla_total_size(sizeof(u16)) + /* TCP_NLA_TIMEOUT_REHASH */
+		nla_total_size(sizeof(u32)) + /* TCP_NLA_BYTES_NOTSENT */
+		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_EDT */
+		nla_total_size(sizeof(u8)) + /* TCP_NLA_TTL */
+		0;
+}
+
+/* Returns TTL or hop limit of an incoming packet from skb. */
+static u8 tcp_skb_ttl_or_hop_limit(const struct sk_buff *skb)
+{
+	if (skb->protocol == htons(ETH_P_IP))
+		return ip_hdr(skb)->ttl;
+	else if (skb->protocol == htons(ETH_P_IPV6))
+		return ipv6_hdr(skb)->hop_limit;
+	else
+		return 0;
+}
+
+struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk,
+					       const struct sk_buff *orig_skb,
+					       const struct sk_buff *ack_skb)
+{
+	const struct tcp_sock *tp = tcp_sk(sk);
+	struct sk_buff *stats;
+	struct tcp_info info;
+	unsigned long rate;
+	u64 rate64;
+
+	stats = alloc_skb(tcp_opt_stats_get_size(), GFP_ATOMIC);
+	if (!stats)
+		return NULL;
+
+	tcp_get_info_chrono_stats(tp, &info);
+	nla_put_u64_64bit(stats, TCP_NLA_BUSY,
+			  info.tcpi_busy_time, TCP_NLA_PAD);
+	nla_put_u64_64bit(stats, TCP_NLA_RWND_LIMITED,
+			  info.tcpi_rwnd_limited, TCP_NLA_PAD);
+	nla_put_u64_64bit(stats, TCP_NLA_SNDBUF_LIMITED,
+			  info.tcpi_sndbuf_limited, TCP_NLA_PAD);
+	nla_put_u64_64bit(stats, TCP_NLA_DATA_SEGS_OUT,
+			  tp->data_segs_out, TCP_NLA_PAD);
+	nla_put_u64_64bit(stats, TCP_NLA_TOTAL_RETRANS,
+			  tp->total_retrans, TCP_NLA_PAD);
+
+	rate = READ_ONCE(sk->sk_pacing_rate);
+	rate64 = (rate != ~0UL) ? rate : ~0ULL;
+	nla_put_u64_64bit(stats, TCP_NLA_PACING_RATE, rate64, TCP_NLA_PAD);
+
+	rate64 = tcp_compute_delivery_rate(tp);
+	nla_put_u64_64bit(stats, TCP_NLA_DELIVERY_RATE, rate64, TCP_NLA_PAD);
+
+	nla_put_u32(stats, TCP_NLA_SND_CWND, tcp_snd_cwnd(tp));
+	nla_put_u32(stats, TCP_NLA_REORDERING, tp->reordering);
+	nla_put_u32(stats, TCP_NLA_MIN_RTT, tcp_min_rtt(tp));
+
+	nla_put_u8(stats, TCP_NLA_RECUR_RETRANS, inet_csk(sk)->icsk_retransmits);
+	nla_put_u8(stats, TCP_NLA_DELIVERY_RATE_APP_LMT, !!tp->rate_app_limited);
+	nla_put_u32(stats, TCP_NLA_SND_SSTHRESH, tp->snd_ssthresh);
+	nla_put_u32(stats, TCP_NLA_DELIVERED, tp->delivered);
+	nla_put_u32(stats, TCP_NLA_DELIVERED_CE, tp->delivered_ce);
+
+	nla_put_u32(stats, TCP_NLA_SNDQ_SIZE, tp->write_seq - tp->snd_una);
+	nla_put_u8(stats, TCP_NLA_CA_STATE, inet_csk(sk)->icsk_ca_state);
+
+	nla_put_u64_64bit(stats, TCP_NLA_BYTES_SENT, tp->bytes_sent,
+			  TCP_NLA_PAD);
+	nla_put_u64_64bit(stats, TCP_NLA_BYTES_RETRANS, tp->bytes_retrans,
+			  TCP_NLA_PAD);
+	nla_put_u32(stats, TCP_NLA_DSACK_DUPS, tp->dsack_dups);
+	nla_put_u32(stats, TCP_NLA_REORD_SEEN, tp->reord_seen);
+	nla_put_u32(stats, TCP_NLA_SRTT, tp->srtt_us >> 3);
+	nla_put_u16(stats, TCP_NLA_TIMEOUT_REHASH, tp->timeout_rehash);
+	nla_put_u32(stats, TCP_NLA_BYTES_NOTSENT,
+		    max_t(int, 0, tp->write_seq - tp->snd_nxt));
+	nla_put_u64_64bit(stats, TCP_NLA_EDT, orig_skb->skb_mstamp_ns,
+			  TCP_NLA_PAD);
+	if (ack_skb)
+		nla_put_u8(stats, TCP_NLA_TTL,
+			   tcp_skb_ttl_or_hop_limit(ack_skb));
+
+	return stats;
+}
+
+int do_tcp_getsockopt(struct sock *sk, int level,
+		      int optname, sockptr_t optval, sockptr_t optlen)
+{
+	struct inet_connection_sock *icsk = inet_csk(sk);
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct net *net = sock_net(sk);
+	int val, len;
+
+	if (copy_from_sockptr(&len, optlen, sizeof(int)))
+		return -EFAULT;
+
+	len = min_t(unsigned int, len, sizeof(int));
+
+	if (len < 0)
+		return -EINVAL;
+
+	switch (optname) {
+	case TCP_MAXSEG:
+		val = tp->mss_cache;
+		if (tp->rx_opt.user_mss &&
+		    ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
+			val = tp->rx_opt.user_mss;
+		if (tp->repair)
+			val = tp->rx_opt.mss_clamp;
+		break;
+	case TCP_NODELAY:
+		val = !!(tp->nonagle&TCP_NAGLE_OFF);
+		break;
+	case TCP_CORK:
+		val = !!(tp->nonagle&TCP_NAGLE_CORK);
+		break;
+	case TCP_KEEPIDLE:
+		val = keepalive_time_when(tp) / HZ;
+		break;
+	case TCP_KEEPINTVL:
+		val = keepalive_intvl_when(tp) / HZ;
+		break;
+	case TCP_KEEPCNT:
+		val = keepalive_probes(tp);
+		break;
+	case TCP_SYNCNT:
+		val = READ_ONCE(icsk->icsk_syn_retries) ? :
+			READ_ONCE(net->ipv4.sysctl_tcp_syn_retries);
+		break;
+	case TCP_LINGER2:
+		val = READ_ONCE(tp->linger2);
+		if (val >= 0)
+			val = (val ? : READ_ONCE(net->ipv4.sysctl_tcp_fin_timeout)) / HZ;
+		break;
+	case TCP_DEFER_ACCEPT:
+		val = READ_ONCE(icsk->icsk_accept_queue.rskq_defer_accept);
+		val = retrans_to_secs(val, TCP_TIMEOUT_INIT / HZ,
+				      TCP_RTO_MAX / HZ);
+		break;
+	case TCP_WINDOW_CLAMP:
+		val = tp->window_clamp;
+		break;
+	case TCP_INFO: {
+		struct tcp_info info;
+
+		if (copy_from_sockptr(&len, optlen, sizeof(int)))
+			return -EFAULT;
+
+		tcp_get_info(sk, &info);
+
+		len = min_t(unsigned int, len, sizeof(info));
+		if (copy_to_sockptr(optlen, &len, sizeof(int)))
+			return -EFAULT;
+		if (copy_to_sockptr(optval, &info, len))
+			return -EFAULT;
+		return 0;
+	}
+	case TCP_CC_INFO: {
+		const struct tcp_congestion_ops *ca_ops;
+		union tcp_cc_info info;
+		size_t sz = 0;
+		int attr;
+
+		if (copy_from_sockptr(&len, optlen, sizeof(int)))
+			return -EFAULT;
+
+		ca_ops = icsk->icsk_ca_ops;
+		if (ca_ops && ca_ops->get_info)
+			sz = ca_ops->get_info(sk, ~0U, &attr, &info);
+
+		len = min_t(unsigned int, len, sz);
+		if (copy_to_sockptr(optlen, &len, sizeof(int)))
+			return -EFAULT;
+		if (copy_to_sockptr(optval, &info, len))
+			return -EFAULT;
+		return 0;
+	}
+	case TCP_QUICKACK:
+		val = !inet_csk_in_pingpong_mode(sk);
+		break;
+
+	case TCP_CONGESTION:
+		if (copy_from_sockptr(&len, optlen, sizeof(int)))
+			return -EFAULT;
+		len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
+		if (copy_to_sockptr(optlen, &len, sizeof(int)))
+			return -EFAULT;
+		if (copy_to_sockptr(optval, icsk->icsk_ca_ops->name, len))
+			return -EFAULT;
+		return 0;
+
+	case TCP_ULP:
+		if (copy_from_sockptr(&len, optlen, sizeof(int)))
+			return -EFAULT;
+		len = min_t(unsigned int, len, TCP_ULP_NAME_MAX);
+		if (!icsk->icsk_ulp_ops) {
+			len = 0;
+			if (copy_to_sockptr(optlen, &len, sizeof(int)))
+				return -EFAULT;
+			return 0;
+		}
+		if (copy_to_sockptr(optlen, &len, sizeof(int)))
+			return -EFAULT;
+		if (copy_to_sockptr(optval, icsk->icsk_ulp_ops->name, len))
+			return -EFAULT;
+		return 0;
+
+	case TCP_FASTOPEN_KEY: {
+		u64 key[TCP_FASTOPEN_KEY_BUF_LENGTH / sizeof(u64)];
+		unsigned int key_len;
+
+		if (copy_from_sockptr(&len, optlen, sizeof(int)))
+			return -EFAULT;
+
+		key_len = tcp_fastopen_get_cipher(net, icsk, key) *
+				TCP_FASTOPEN_KEY_LENGTH;
+		len = min_t(unsigned int, len, key_len);
+		if (copy_to_sockptr(optlen, &len, sizeof(int)))
+			return -EFAULT;
+		if (copy_to_sockptr(optval, key, len))
+			return -EFAULT;
+		return 0;
+	}
+	case TCP_THIN_LINEAR_TIMEOUTS:
+		val = tp->thin_lto;
+		break;
+
+	case TCP_THIN_DUPACK:
+		val = 0;
+		break;
+
+	case TCP_REPAIR:
+		val = tp->repair;
+		break;
+
+	case TCP_REPAIR_QUEUE:
+		if (tp->repair)
+			val = tp->repair_queue;
+		else
+			return -EINVAL;
+		break;
+
+	case TCP_REPAIR_WINDOW: {
+		struct tcp_repair_window opt;
+
+		if (copy_from_sockptr(&len, optlen, sizeof(int)))
+			return -EFAULT;
+
+		if (len != sizeof(opt))
+			return -EINVAL;
+
+		if (!tp->repair)
+			return -EPERM;
+
+		opt.snd_wl1	= tp->snd_wl1;
+		opt.snd_wnd	= tp->snd_wnd;
+		opt.max_window	= tp->max_window;
+		opt.rcv_wnd	= tp->rcv_wnd;
+		opt.rcv_wup	= tp->rcv_wup;
+
+		if (copy_to_sockptr(optval, &opt, len))
+			return -EFAULT;
+		return 0;
+	}
+	case TCP_QUEUE_SEQ:
+		if (tp->repair_queue == TCP_SEND_QUEUE)
+			val = tp->write_seq;
+		else if (tp->repair_queue == TCP_RECV_QUEUE)
+			val = tp->rcv_nxt;
+		else
+			return -EINVAL;
+		break;
+
+	case TCP_USER_TIMEOUT:
+		val = READ_ONCE(icsk->icsk_user_timeout);
+		break;
+
+	case TCP_FASTOPEN:
+		val = READ_ONCE(icsk->icsk_accept_queue.fastopenq.max_qlen);
+		break;
+
+	case TCP_FASTOPEN_CONNECT:
+		val = tp->fastopen_connect;
+		break;
+
+	case TCP_FASTOPEN_NO_COOKIE:
+		val = tp->fastopen_no_cookie;
+		break;
+
+	case TCP_TX_DELAY:
+		val = READ_ONCE(tp->tcp_tx_delay);
+		break;
+
+	case TCP_TIMESTAMP:
+		val = tcp_time_stamp_raw() + READ_ONCE(tp->tsoffset);
+		break;
+	case TCP_NOTSENT_LOWAT:
+		val = READ_ONCE(tp->notsent_lowat);
+		break;
+	case TCP_INQ:
+		val = tp->recvmsg_inq;
+		break;
+	case TCP_SAVE_SYN:
+		val = tp->save_syn;
+		break;
+	case TCP_SAVED_SYN: {
+		if (copy_from_sockptr(&len, optlen, sizeof(int)))
+			return -EFAULT;
+
+		sockopt_lock_sock(sk);
+		if (tp->saved_syn) {
+			if (len < tcp_saved_syn_len(tp->saved_syn)) {
+				len = tcp_saved_syn_len(tp->saved_syn);
+				if (copy_to_sockptr(optlen, &len, sizeof(int))) {
+					sockopt_release_sock(sk);
+					return -EFAULT;
+				}
+				sockopt_release_sock(sk);
+				return -EINVAL;
+			}
+			len = tcp_saved_syn_len(tp->saved_syn);
+			if (copy_to_sockptr(optlen, &len, sizeof(int))) {
+				sockopt_release_sock(sk);
+				return -EFAULT;
+			}
+			if (copy_to_sockptr(optval, tp->saved_syn->data, len)) {
+				sockopt_release_sock(sk);
+				return -EFAULT;
+			}
+			tcp_saved_syn_free(tp);
+			sockopt_release_sock(sk);
+		} else {
+			sockopt_release_sock(sk);
+			len = 0;
+			if (copy_to_sockptr(optlen, &len, sizeof(int)))
+				return -EFAULT;
+		}
+		return 0;
+	}
+#ifdef CONFIG_MMU
+	case TCP_ZEROCOPY_RECEIVE: {
+		struct scm_timestamping_internal tss;
+		struct tcp_zerocopy_receive zc = {};
+		int err;
+
+		if (copy_from_sockptr(&len, optlen, sizeof(int)))
+			return -EFAULT;
+		if (len < 0 ||
+		    len < offsetofend(struct tcp_zerocopy_receive, length))
+			return -EINVAL;
+		if (unlikely(len > sizeof(zc))) {
+			err = check_zeroed_sockptr(optval, sizeof(zc),
+						   len - sizeof(zc));
+			if (err < 1)
+				return err == 0 ? -EINVAL : err;
+			len = sizeof(zc);
+			if (copy_to_sockptr(optlen, &len, sizeof(int)))
+				return -EFAULT;
+		}
+		if (copy_from_sockptr(&zc, optval, len))
+			return -EFAULT;
+		if (zc.reserved)
+			return -EINVAL;
+		if (zc.msg_flags &  ~(TCP_VALID_ZC_MSG_FLAGS))
+			return -EINVAL;
+		sockopt_lock_sock(sk);
+		err = tcp_zerocopy_receive(sk, &zc, &tss);
+		err = BPF_CGROUP_RUN_PROG_GETSOCKOPT_KERN(sk, level, optname,
+							  &zc, &len, err);
+		sockopt_release_sock(sk);
+		if (len >= offsetofend(struct tcp_zerocopy_receive, msg_flags))
+			goto zerocopy_rcv_cmsg;
+		switch (len) {
+		case offsetofend(struct tcp_zerocopy_receive, msg_flags):
+			goto zerocopy_rcv_cmsg;
+		case offsetofend(struct tcp_zerocopy_receive, msg_controllen):
+		case offsetofend(struct tcp_zerocopy_receive, msg_control):
+		case offsetofend(struct tcp_zerocopy_receive, flags):
+		case offsetofend(struct tcp_zerocopy_receive, copybuf_len):
+		case offsetofend(struct tcp_zerocopy_receive, copybuf_address):
+		case offsetofend(struct tcp_zerocopy_receive, err):
+			goto zerocopy_rcv_sk_err;
+		case offsetofend(struct tcp_zerocopy_receive, inq):
+			goto zerocopy_rcv_inq;
+		case offsetofend(struct tcp_zerocopy_receive, length):
+		default:
+			goto zerocopy_rcv_out;
+		}
+zerocopy_rcv_cmsg:
+		if (zc.msg_flags & TCP_CMSG_TS)
+			tcp_zc_finalize_rx_tstamp(sk, &zc, &tss);
+		else
+			zc.msg_flags = 0;
+zerocopy_rcv_sk_err:
+		if (!err)
+			zc.err = sock_error(sk);
+zerocopy_rcv_inq:
+		zc.inq = tcp_inq_hint(sk);
+zerocopy_rcv_out:
+		if (!err && copy_to_sockptr(optval, &zc, len))
+			err = -EFAULT;
+		return err;
+	}
+#endif
+	default:
+		return -ENOPROTOOPT;
+	}
+
+	if (copy_to_sockptr(optlen, &len, sizeof(int)))
+		return -EFAULT;
+	if (copy_to_sockptr(optval, &val, len))
+		return -EFAULT;
+	return 0;
+}
+
+bool tcp_bpf_bypass_getsockopt(int level, int optname)
+{
+	/* TCP do_tcp_getsockopt has optimized getsockopt implementation
+	 * to avoid extra socket lock for TCP_ZEROCOPY_RECEIVE.
+	 */
+	if (level == SOL_TCP && optname == TCP_ZEROCOPY_RECEIVE)
+		return true;
+
+	return false;
+}
+EXPORT_SYMBOL(tcp_bpf_bypass_getsockopt);
+
+int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
+		   int __user *optlen)
+{
+	struct inet_connection_sock *icsk = inet_csk(sk);
+
+	if (level != SOL_TCP)
+		/* Paired with WRITE_ONCE() in do_ipv6_setsockopt() and tcp_v6_connect() */
+		return READ_ONCE(icsk->icsk_af_ops)->getsockopt(sk, level, optname,
+								optval, optlen);
+	return do_tcp_getsockopt(sk, level, optname, USER_SOCKPTR(optval),
+				 USER_SOCKPTR(optlen));
+}
+EXPORT_SYMBOL(tcp_getsockopt);
+
+#ifdef CONFIG_TCP_MD5SIG
+static DEFINE_PER_CPU(struct tcp_md5sig_pool, tcp_md5sig_pool);
+static DEFINE_MUTEX(tcp_md5sig_mutex);
+static bool tcp_md5sig_pool_populated = false;
+
+static void __tcp_alloc_md5sig_pool(void)
+{
+	struct crypto_ahash *hash;
+	int cpu;
+
+	hash = crypto_alloc_ahash("md5", 0, CRYPTO_ALG_ASYNC);
+	if (IS_ERR(hash))
+		return;
+
+	for_each_possible_cpu(cpu) {
+		void *scratch = per_cpu(tcp_md5sig_pool, cpu).scratch;
+		struct ahash_request *req;
+
+		if (!scratch) {
+			scratch = kmalloc_node(sizeof(union tcp_md5sum_block) +
+					       sizeof(struct tcphdr),
+					       GFP_KERNEL,
+					       cpu_to_node(cpu));
+			if (!scratch)
+				return;
+			per_cpu(tcp_md5sig_pool, cpu).scratch = scratch;
+		}
+		if (per_cpu(tcp_md5sig_pool, cpu).md5_req)
+			continue;
+
+		req = ahash_request_alloc(hash, GFP_KERNEL);
+		if (!req)
+			return;
+
+		ahash_request_set_callback(req, 0, NULL, NULL);
+
+		per_cpu(tcp_md5sig_pool, cpu).md5_req = req;
+	}
+	/* before setting tcp_md5sig_pool_populated, we must commit all writes
+	 * to memory. See smp_rmb() in tcp_get_md5sig_pool()
+	 */
+	smp_wmb();
+	/* Paired with READ_ONCE() from tcp_alloc_md5sig_pool()
+	 * and tcp_get_md5sig_pool().
+	*/
+	WRITE_ONCE(tcp_md5sig_pool_populated, true);
+}
+
+bool tcp_alloc_md5sig_pool(void)
+{
+	/* Paired with WRITE_ONCE() from __tcp_alloc_md5sig_pool() */
+	if (unlikely(!READ_ONCE(tcp_md5sig_pool_populated))) {
+		mutex_lock(&tcp_md5sig_mutex);
+
+		if (!tcp_md5sig_pool_populated) {
+			__tcp_alloc_md5sig_pool();
+			if (tcp_md5sig_pool_populated)
+				static_branch_inc(&tcp_md5_needed);
+		}
+
+		mutex_unlock(&tcp_md5sig_mutex);
+	}
+	/* Paired with WRITE_ONCE() from __tcp_alloc_md5sig_pool() */
+	return READ_ONCE(tcp_md5sig_pool_populated);
+}
+EXPORT_SYMBOL(tcp_alloc_md5sig_pool);
+
+
+/**
+ *	tcp_get_md5sig_pool - get md5sig_pool for this user
+ *
+ *	We use percpu structure, so if we succeed, we exit with preemption
+ *	and BH disabled, to make sure another thread or softirq handling
+ *	wont try to get same context.
+ */
+struct tcp_md5sig_pool *tcp_get_md5sig_pool(void)
+{
+	local_bh_disable();
+
+	/* Paired with WRITE_ONCE() from __tcp_alloc_md5sig_pool() */
+	if (READ_ONCE(tcp_md5sig_pool_populated)) {
+		/* coupled with smp_wmb() in __tcp_alloc_md5sig_pool() */
+		smp_rmb();
+		return this_cpu_ptr(&tcp_md5sig_pool);
+	}
+	local_bh_enable();
+	return NULL;
+}
+EXPORT_SYMBOL(tcp_get_md5sig_pool);
+
+int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *hp,
+			  const struct sk_buff *skb, unsigned int header_len)
+{
+	struct scatterlist sg;
+	const struct tcphdr *tp = tcp_hdr(skb);
+	struct ahash_request *req = hp->md5_req;
+	unsigned int i;
+	const unsigned int head_data_len = skb_headlen(skb) > header_len ?
+					   skb_headlen(skb) - header_len : 0;
+	const struct skb_shared_info *shi = skb_shinfo(skb);
+	struct sk_buff *frag_iter;
+
+	sg_init_table(&sg, 1);
+
+	sg_set_buf(&sg, ((u8 *) tp) + header_len, head_data_len);
+	ahash_request_set_crypt(req, &sg, NULL, head_data_len);
+	if (crypto_ahash_update(req))
+		return 1;
+
+	for (i = 0; i < shi->nr_frags; ++i) {
+		const skb_frag_t *f = &shi->frags[i];
+		unsigned int offset = skb_frag_off(f);
+		struct page *page = skb_frag_page(f) + (offset >> PAGE_SHIFT);
+
+		sg_set_page(&sg, page, skb_frag_size(f),
+			    offset_in_page(offset));
+		ahash_request_set_crypt(req, &sg, NULL, skb_frag_size(f));
+		if (crypto_ahash_update(req))
+			return 1;
+	}
+
+	skb_walk_frags(skb, frag_iter)
+		if (tcp_md5_hash_skb_data(hp, frag_iter, 0))
+			return 1;
+
+	return 0;
+}
+EXPORT_SYMBOL(tcp_md5_hash_skb_data);
+
+int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, const struct tcp_md5sig_key *key)
+{
+	u8 keylen = READ_ONCE(key->keylen); /* paired with WRITE_ONCE() in tcp_md5_do_add */
+	struct scatterlist sg;
+
+	sg_init_one(&sg, key->key, keylen);
+	ahash_request_set_crypt(hp->md5_req, &sg, NULL, keylen);
+
+	/* We use data_race() because tcp_md5_do_add() might change key->key under us */
+	return data_race(crypto_ahash_update(hp->md5_req));
+}
+EXPORT_SYMBOL(tcp_md5_hash_key);
+
+/* Called with rcu_read_lock() */
+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)
+{
+	/*
+	 * This gets called for each TCP segment that arrives
+	 * so we want to be efficient.
+	 * We have 3 drop cases:
+	 * o No MD5 hash and one expected.
+	 * o MD5 hash and we're not expecting one.
+	 * o MD5 hash and its wrong.
+	 */
+	const __u8 *hash_location = NULL;
+	struct tcp_md5sig_key *hash_expected;
+	const struct tcphdr *th = tcp_hdr(skb);
+	struct tcp_sock *tp = tcp_sk(sk);
+	int genhash, l3index;
+	u8 newhash[16];
+
+	/* sdif set, means packet ingressed via a device
+	 * in an L3 domain and dif is set to the l3mdev
+	 */
+	l3index = sdif ? dif : 0;
+
+	hash_expected = tcp_md5_do_lookup(sk, l3index, saddr, family);
+	hash_location = tcp_parse_md5sig_option(th);
+
+	/* We've parsed the options - do we have a hash? */
+	if (!hash_expected && !hash_location)
+		return SKB_NOT_DROPPED_YET;
+
+	if (hash_expected && !hash_location) {
+		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
+		return SKB_DROP_REASON_TCP_MD5NOTFOUND;
+	}
+
+	if (!hash_expected && hash_location) {
+		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
+		return SKB_DROP_REASON_TCP_MD5UNEXPECTED;
+	}
+
+	/* Check the signature.
+	 * To support dual stack listeners, we need to handle
+	 * IPv4-mapped case.
+	 */
+	if (family == AF_INET)
+		genhash = tcp_v4_md5_hash_skb(newhash,
+					      hash_expected,
+					      NULL, skb);
+	else
+		genhash = tp->af_specific->calc_md5_hash(newhash,
+							 hash_expected,
+							 NULL, skb);
+
+	if (genhash || memcmp(hash_location, newhash, 16) != 0) {
+		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5FAILURE);
+		if (family == AF_INET) {
+			net_info_ratelimited("MD5 Hash failed for (%pI4, %d)->(%pI4, %d)%s L3 index %d\n",
+					saddr, ntohs(th->source),
+					daddr, ntohs(th->dest),
+					genhash ? " tcp_v4_calc_md5_hash failed"
+					: "", l3index);
+		} else {
+			net_info_ratelimited("MD5 Hash %s for [%pI6c]:%u->[%pI6c]:%u L3 index %d\n",
+					genhash ? "failed" : "mismatch",
+					saddr, ntohs(th->source),
+					daddr, ntohs(th->dest), l3index);
+		}
+		return SKB_DROP_REASON_TCP_MD5FAILURE;
+	}
+	return SKB_NOT_DROPPED_YET;
+}
+EXPORT_SYMBOL(tcp_inbound_md5_hash);
+
+#endif
+
+void tcp_done(struct sock *sk)
+{
+	struct request_sock *req;
+
+	/* We might be called with a new socket, after
+	 * inet_csk_prepare_forced_close() has been called
+	 * so we can not use lockdep_sock_is_held(sk)
+	 */
+	req = rcu_dereference_protected(tcp_sk(sk)->fastopen_rsk, 1);
+
+	if (sk->sk_state == TCP_SYN_SENT || sk->sk_state == TCP_SYN_RECV)
+		TCP_INC_STATS(sock_net(sk), TCP_MIB_ATTEMPTFAILS);
+
+	tcp_set_state(sk, TCP_CLOSE);
+	tcp_clear_xmit_timers(sk);
+	if (req)
+		reqsk_fastopen_remove(sk, req, false);
+
+	WRITE_ONCE(sk->sk_shutdown, SHUTDOWN_MASK);
+
+	if (!sock_flag(sk, SOCK_DEAD))
+		sk->sk_state_change(sk);
+	else
+		inet_csk_destroy_sock(sk);
+}
+EXPORT_SYMBOL_GPL(tcp_done);
+
+int tcp_abort(struct sock *sk, int err)
+{
+	int state = inet_sk_state_load(sk);
+
+	if (state == TCP_NEW_SYN_RECV) {
+		struct request_sock *req = inet_reqsk(sk);
+
+		local_bh_disable();
+		inet_csk_reqsk_queue_drop(req->rsk_listener, req);
+		local_bh_enable();
+		return 0;
+	}
+	if (state == TCP_TIME_WAIT) {
+		struct inet_timewait_sock *tw = inet_twsk(sk);
+
+		refcount_inc(&tw->tw_refcnt);
+		local_bh_disable();
+		inet_twsk_deschedule_put(tw);
+		local_bh_enable();
+		return 0;
+	}
+
+	/* Don't race with userspace socket closes such as tcp_close. */
+	lock_sock(sk);
+
+	if (sk->sk_state == TCP_LISTEN) {
+		tcp_set_state(sk, TCP_CLOSE);
+		inet_csk_listen_stop(sk);
+	}
+
+	/* Don't race with BH socket closes such as inet_csk_listen_stop. */
+	local_bh_disable();
+	bh_lock_sock(sk);
+
+	if (!sock_flag(sk, SOCK_DEAD)) {
+		sk->sk_err = err;
+		/* This barrier is coupled with smp_rmb() in tcp_poll() */
+		smp_wmb();
+		sk_error_report(sk);
+		if (tcp_need_reset(sk->sk_state))
+			tcp_send_active_reset(sk, GFP_ATOMIC);
+		tcp_done(sk);
+	}
+
+	bh_unlock_sock(sk);
+	local_bh_enable();
+	tcp_write_queue_purge(sk);
+	release_sock(sk);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(tcp_abort);
+
+extern struct tcp_congestion_ops tcp_reno;
+
+static __initdata unsigned long thash_entries;
+static int __init set_thash_entries(char *str)
+{
+	ssize_t ret;
+
+	if (!str)
+		return 0;
+
+	ret = kstrtoul(str, 0, &thash_entries);
+	if (ret)
+		return 0;
+
+	return 1;
+}
+__setup("thash_entries=", set_thash_entries);
+
+static void __init tcp_init_mem(void)
+{
+	unsigned long limit = nr_free_buffer_pages() / 16;
+
+	limit = max(limit, 128UL);
+	sysctl_tcp_mem[0] = limit / 4 * 3;		/* 4.68 % */
+	sysctl_tcp_mem[1] = limit;			/* 6.25 % */
+	sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2;	/* 9.37 % */
+}
+
+void __init tcp_init(void)
+{
+	int max_rshare, max_wshare, cnt;
+	unsigned long limit;
+	unsigned int i;
+
+	BUILD_BUG_ON(TCP_MIN_SND_MSS <= MAX_TCP_OPTION_SPACE);
+	BUILD_BUG_ON(sizeof(struct tcp_skb_cb) >
+		     sizeof_field(struct sk_buff, cb));
+
+	percpu_counter_init(&tcp_sockets_allocated, 0, GFP_KERNEL);
+
+	timer_setup(&tcp_orphan_timer, tcp_orphan_update, TIMER_DEFERRABLE);
+	mod_timer(&tcp_orphan_timer, jiffies + TCP_ORPHAN_TIMER_PERIOD);
+
+	inet_hashinfo2_init(&tcp_hashinfo, "tcp_listen_portaddr_hash",
+			    thash_entries, 21,  /* one slot per 2 MB*/
+			    0, 64 * 1024);
+	tcp_hashinfo.bind_bucket_cachep =
+		kmem_cache_create("tcp_bind_bucket",
+				  sizeof(struct inet_bind_bucket), 0,
+				  SLAB_HWCACHE_ALIGN | SLAB_PANIC |
+				  SLAB_ACCOUNT,
+				  NULL);
+	tcp_hashinfo.bind2_bucket_cachep =
+		kmem_cache_create("tcp_bind2_bucket",
+				  sizeof(struct inet_bind2_bucket), 0,
+				  SLAB_HWCACHE_ALIGN | SLAB_PANIC |
+				  SLAB_ACCOUNT,
+				  NULL);
+
+	/* Size and allocate the main established and bind bucket
+	 * hash tables.
+	 *
+	 * The methodology is similar to that of the buffer cache.
+	 */
+	tcp_hashinfo.ehash =
+		alloc_large_system_hash("TCP established",
+					sizeof(struct inet_ehash_bucket),
+					thash_entries,
+					17, /* one slot per 128 KB of memory */
+					0,
+					NULL,
+					&tcp_hashinfo.ehash_mask,
+					0,
+					thash_entries ? 0 : 512 * 1024);
+	for (i = 0; i <= tcp_hashinfo.ehash_mask; i++)
+		INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].chain, i);
+
+	if (inet_ehash_locks_alloc(&tcp_hashinfo))
+		panic("TCP: failed to alloc ehash_locks");
+	tcp_hashinfo.bhash =
+		alloc_large_system_hash("TCP bind",
+					2 * sizeof(struct inet_bind_hashbucket),
+					tcp_hashinfo.ehash_mask + 1,
+					17, /* one slot per 128 KB of memory */
+					0,
+					&tcp_hashinfo.bhash_size,
+					NULL,
+					0,
+					64 * 1024);
+	tcp_hashinfo.bhash_size = 1U << tcp_hashinfo.bhash_size;
+	tcp_hashinfo.bhash2 = tcp_hashinfo.bhash + tcp_hashinfo.bhash_size;
+	for (i = 0; i < tcp_hashinfo.bhash_size; i++) {
+		spin_lock_init(&tcp_hashinfo.bhash[i].lock);
+		INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain);
+		spin_lock_init(&tcp_hashinfo.bhash2[i].lock);
+		INIT_HLIST_HEAD(&tcp_hashinfo.bhash2[i].chain);
+	}
+
+	tcp_hashinfo.pernet = false;
+
+	cnt = tcp_hashinfo.ehash_mask + 1;
+	sysctl_tcp_max_orphans = cnt / 2;
+
+	tcp_init_mem();
+	/* Set per-socket limits to no more than 1/128 the pressure threshold */
+	limit = nr_free_buffer_pages() << (PAGE_SHIFT - 7);
+	max_wshare = min(4UL*1024*1024, limit);
+	max_rshare = min(6UL*1024*1024, limit);
+
+	init_net.ipv4.sysctl_tcp_wmem[0] = PAGE_SIZE;
+	init_net.ipv4.sysctl_tcp_wmem[1] = 16*1024;
+	init_net.ipv4.sysctl_tcp_wmem[2] = max(64*1024, max_wshare);
+
+	init_net.ipv4.sysctl_tcp_rmem[0] = PAGE_SIZE;
+	init_net.ipv4.sysctl_tcp_rmem[1] = 131072;
+	init_net.ipv4.sysctl_tcp_rmem[2] = max(131072, max_rshare);
+
+	pr_info("Hash tables configured (established %u bind %u)\n",
+		tcp_hashinfo.ehash_mask + 1, tcp_hashinfo.bhash_size);
+
+	tcp_v4_init();
+	tcp_metrics_init();
+	BUG_ON(tcp_register_congestion_control(&tcp_reno) != 0);
+	tcp_tasklet_init();
+	mptcp_init();
+}