xref: /openbmc/linux/net/ipv4/tcp.c (revision 27ab1c1c)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * INET		An implementation of the TCP/IP protocol suite for the LINUX
4  *		operating system.  INET is implemented using the  BSD Socket
5  *		interface as the means of communication with the user level.
6  *
7  *		Implementation of the Transmission Control Protocol(TCP).
8  *
9  * Authors:	Ross Biro
10  *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
11  *		Mark Evans, <evansmp@uhura.aston.ac.uk>
12  *		Corey Minyard <wf-rch!minyard@relay.EU.net>
13  *		Florian La Roche, <flla@stud.uni-sb.de>
14  *		Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
15  *		Linus Torvalds, <torvalds@cs.helsinki.fi>
16  *		Alan Cox, <gw4pts@gw4pts.ampr.org>
17  *		Matthew Dillon, <dillon@apollo.west.oic.com>
18  *		Arnt Gulbrandsen, <agulbra@nvg.unit.no>
19  *		Jorge Cwik, <jorge@laser.satlink.net>
20  *
21  * Fixes:
22  *		Alan Cox	:	Numerous verify_area() calls
23  *		Alan Cox	:	Set the ACK bit on a reset
24  *		Alan Cox	:	Stopped it crashing if it closed while
25  *					sk->inuse=1 and was trying to connect
26  *					(tcp_err()).
27  *		Alan Cox	:	All icmp error handling was broken
28  *					pointers passed where wrong and the
29  *					socket was looked up backwards. Nobody
30  *					tested any icmp error code obviously.
31  *		Alan Cox	:	tcp_err() now handled properly. It
32  *					wakes people on errors. poll
33  *					behaves and the icmp error race
34  *					has gone by moving it into sock.c
35  *		Alan Cox	:	tcp_send_reset() fixed to work for
36  *					everything not just packets for
37  *					unknown sockets.
38  *		Alan Cox	:	tcp option processing.
39  *		Alan Cox	:	Reset tweaked (still not 100%) [Had
40  *					syn rule wrong]
41  *		Herp Rosmanith  :	More reset fixes
42  *		Alan Cox	:	No longer acks invalid rst frames.
43  *					Acking any kind of RST is right out.
44  *		Alan Cox	:	Sets an ignore me flag on an rst
45  *					receive otherwise odd bits of prattle
46  *					escape still
47  *		Alan Cox	:	Fixed another acking RST frame bug.
48  *					Should stop LAN workplace lockups.
49  *		Alan Cox	: 	Some tidyups using the new skb list
50  *					facilities
51  *		Alan Cox	:	sk->keepopen now seems to work
52  *		Alan Cox	:	Pulls options out correctly on accepts
53  *		Alan Cox	:	Fixed assorted sk->rqueue->next errors
54  *		Alan Cox	:	PSH doesn't end a TCP read. Switched a
55  *					bit to skb ops.
56  *		Alan Cox	:	Tidied tcp_data to avoid a potential
57  *					nasty.
58  *		Alan Cox	:	Added some better commenting, as the
59  *					tcp is hard to follow
60  *		Alan Cox	:	Removed incorrect check for 20 * psh
61  *	Michael O'Reilly	:	ack < copied bug fix.
62  *	Johannes Stille		:	Misc tcp fixes (not all in yet).
63  *		Alan Cox	:	FIN with no memory -> CRASH
64  *		Alan Cox	:	Added socket option proto entries.
65  *					Also added awareness of them to accept.
66  *		Alan Cox	:	Added TCP options (SOL_TCP)
67  *		Alan Cox	:	Switched wakeup calls to callbacks,
68  *					so the kernel can layer network
69  *					sockets.
70  *		Alan Cox	:	Use ip_tos/ip_ttl settings.
71  *		Alan Cox	:	Handle FIN (more) properly (we hope).
72  *		Alan Cox	:	RST frames sent on unsynchronised
73  *					state ack error.
74  *		Alan Cox	:	Put in missing check for SYN bit.
75  *		Alan Cox	:	Added tcp_select_window() aka NET2E
76  *					window non shrink trick.
77  *		Alan Cox	:	Added a couple of small NET2E timer
78  *					fixes
79  *		Charles Hedrick :	TCP fixes
80  *		Toomas Tamm	:	TCP window fixes
81  *		Alan Cox	:	Small URG fix to rlogin ^C ack fight
82  *		Charles Hedrick	:	Rewrote most of it to actually work
83  *		Linus		:	Rewrote tcp_read() and URG handling
84  *					completely
85  *		Gerhard Koerting:	Fixed some missing timer handling
86  *		Matthew Dillon  :	Reworked TCP machine states as per RFC
87  *		Gerhard Koerting:	PC/TCP workarounds
88  *		Adam Caldwell	:	Assorted timer/timing errors
89  *		Matthew Dillon	:	Fixed another RST bug
90  *		Alan Cox	:	Move to kernel side addressing changes.
91  *		Alan Cox	:	Beginning work on TCP fastpathing
92  *					(not yet usable)
93  *		Arnt Gulbrandsen:	Turbocharged tcp_check() routine.
94  *		Alan Cox	:	TCP fast path debugging
95  *		Alan Cox	:	Window clamping
96  *		Michael Riepe	:	Bug in tcp_check()
97  *		Matt Dillon	:	More TCP improvements and RST bug fixes
98  *		Matt Dillon	:	Yet more small nasties remove from the
99  *					TCP code (Be very nice to this man if
100  *					tcp finally works 100%) 8)
101  *		Alan Cox	:	BSD accept semantics.
102  *		Alan Cox	:	Reset on closedown bug.
103  *	Peter De Schrijver	:	ENOTCONN check missing in tcp_sendto().
104  *		Michael Pall	:	Handle poll() after URG properly in
105  *					all cases.
106  *		Michael Pall	:	Undo the last fix in tcp_read_urg()
107  *					(multi URG PUSH broke rlogin).
108  *		Michael Pall	:	Fix the multi URG PUSH problem in
109  *					tcp_readable(), poll() after URG
110  *					works now.
111  *		Michael Pall	:	recv(...,MSG_OOB) never blocks in the
112  *					BSD api.
113  *		Alan Cox	:	Changed the semantics of sk->socket to
114  *					fix a race and a signal problem with
115  *					accept() and async I/O.
116  *		Alan Cox	:	Relaxed the rules on tcp_sendto().
117  *		Yury Shevchuk	:	Really fixed accept() blocking problem.
118  *		Craig I. Hagan  :	Allow for BSD compatible TIME_WAIT for
119  *					clients/servers which listen in on
120  *					fixed ports.
121  *		Alan Cox	:	Cleaned the above up and shrank it to
122  *					a sensible code size.
123  *		Alan Cox	:	Self connect lockup fix.
124  *		Alan Cox	:	No connect to multicast.
125  *		Ross Biro	:	Close unaccepted children on master
126  *					socket close.
127  *		Alan Cox	:	Reset tracing code.
128  *		Alan Cox	:	Spurious resets on shutdown.
129  *		Alan Cox	:	Giant 15 minute/60 second timer error
130  *		Alan Cox	:	Small whoops in polling before an
131  *					accept.
132  *		Alan Cox	:	Kept the state trace facility since
133  *					it's handy for debugging.
134  *		Alan Cox	:	More reset handler fixes.
135  *		Alan Cox	:	Started rewriting the code based on
136  *					the RFC's for other useful protocol
137  *					references see: Comer, KA9Q NOS, and
138  *					for a reference on the difference
139  *					between specifications and how BSD
140  *					works see the 4.4lite source.
141  *		A.N.Kuznetsov	:	Don't time wait on completion of tidy
142  *					close.
143  *		Linus Torvalds	:	Fin/Shutdown & copied_seq changes.
144  *		Linus Torvalds	:	Fixed BSD port reuse to work first syn
145  *		Alan Cox	:	Reimplemented timers as per the RFC
146  *					and using multiple timers for sanity.
147  *		Alan Cox	:	Small bug fixes, and a lot of new
148  *					comments.
149  *		Alan Cox	:	Fixed dual reader crash by locking
150  *					the buffers (much like datagram.c)
151  *		Alan Cox	:	Fixed stuck sockets in probe. A probe
152  *					now gets fed up of retrying without
153  *					(even a no space) answer.
154  *		Alan Cox	:	Extracted closing code better
155  *		Alan Cox	:	Fixed the closing state machine to
156  *					resemble the RFC.
157  *		Alan Cox	:	More 'per spec' fixes.
158  *		Jorge Cwik	:	Even faster checksumming.
159  *		Alan Cox	:	tcp_data() doesn't ack illegal PSH
160  *					only frames. At least one pc tcp stack
161  *					generates them.
162  *		Alan Cox	:	Cache last socket.
163  *		Alan Cox	:	Per route irtt.
164  *		Matt Day	:	poll()->select() match BSD precisely on error
165  *		Alan Cox	:	New buffers
166  *		Marc Tamsky	:	Various sk->prot->retransmits and
167  *					sk->retransmits misupdating fixed.
168  *					Fixed tcp_write_timeout: stuck close,
169  *					and TCP syn retries gets used now.
170  *		Mark Yarvis	:	In tcp_read_wakeup(), don't send an
171  *					ack if state is TCP_CLOSED.
172  *		Alan Cox	:	Look up device on a retransmit - routes may
173  *					change. Doesn't yet cope with MSS shrink right
174  *					but it's a start!
175  *		Marc Tamsky	:	Closing in closing fixes.
176  *		Mike Shaver	:	RFC1122 verifications.
177  *		Alan Cox	:	rcv_saddr errors.
178  *		Alan Cox	:	Block double connect().
179  *		Alan Cox	:	Small hooks for enSKIP.
180  *		Alexey Kuznetsov:	Path MTU discovery.
181  *		Alan Cox	:	Support soft errors.
182  *		Alan Cox	:	Fix MTU discovery pathological case
183  *					when the remote claims no mtu!
184  *		Marc Tamsky	:	TCP_CLOSE fix.
185  *		Colin (G3TNE)	:	Send a reset on syn ack replies in
186  *					window but wrong (fixes NT lpd problems)
187  *		Pedro Roque	:	Better TCP window handling, delayed ack.
188  *		Joerg Reuter	:	No modification of locked buffers in
189  *					tcp_do_retransmit()
190  *		Eric Schenk	:	Changed receiver side silly window
191  *					avoidance algorithm to BSD style
192  *					algorithm. This doubles throughput
193  *					against machines running Solaris,
194  *					and seems to result in general
195  *					improvement.
196  *	Stefan Magdalinski	:	adjusted tcp_readable() to fix FIONREAD
197  *	Willy Konynenberg	:	Transparent proxying support.
198  *	Mike McLagan		:	Routing by source
199  *		Keith Owens	:	Do proper merging with partial SKB's in
200  *					tcp_do_sendmsg to avoid burstiness.
201  *		Eric Schenk	:	Fix fast close down bug with
202  *					shutdown() followed by close().
203  *		Andi Kleen 	:	Make poll agree with SIGIO
204  *	Salvatore Sanfilippo	:	Support SO_LINGER with linger == 1 and
205  *					lingertime == 0 (RFC 793 ABORT Call)
206  *	Hirokazu Takahashi	:	Use copy_from_user() instead of
207  *					csum_and_copy_from_user() if possible.
208  *
209  * Description of States:
210  *
211  *	TCP_SYN_SENT		sent a connection request, waiting for ack
212  *
213  *	TCP_SYN_RECV		received a connection request, sent ack,
214  *				waiting for final ack in three-way handshake.
215  *
216  *	TCP_ESTABLISHED		connection established
217  *
218  *	TCP_FIN_WAIT1		our side has shutdown, waiting to complete
219  *				transmission of remaining buffered data
220  *
221  *	TCP_FIN_WAIT2		all buffered data sent, waiting for remote
222  *				to shutdown
223  *
224  *	TCP_CLOSING		both sides have shutdown but we still have
225  *				data we have to finish sending
226  *
227  *	TCP_TIME_WAIT		timeout to catch resent junk before entering
228  *				closed, can only be entered from FIN_WAIT2
229  *				or CLOSING.  Required because the other end
230  *				may not have gotten our last ACK causing it
231  *				to retransmit the data packet (which we ignore)
232  *
233  *	TCP_CLOSE_WAIT		remote side has shutdown and is waiting for
234  *				us to finish writing our data and to shutdown
235  *				(we have to close() to move on to LAST_ACK)
236  *
237  *	TCP_LAST_ACK		out side has shutdown after remote has
238  *				shutdown.  There may still be data in our
239  *				buffer that we have to finish sending
240  *
241  *	TCP_CLOSE		socket is finished
242  */
243 
244 #define pr_fmt(fmt) "TCP: " fmt
245 
246 #include <crypto/hash.h>
247 #include <linux/kernel.h>
248 #include <linux/module.h>
249 #include <linux/types.h>
250 #include <linux/fcntl.h>
251 #include <linux/poll.h>
252 #include <linux/inet_diag.h>
253 #include <linux/init.h>
254 #include <linux/fs.h>
255 #include <linux/skbuff.h>
256 #include <linux/scatterlist.h>
257 #include <linux/splice.h>
258 #include <linux/net.h>
259 #include <linux/socket.h>
260 #include <linux/random.h>
261 #include <linux/memblock.h>
262 #include <linux/highmem.h>
263 #include <linux/swap.h>
264 #include <linux/cache.h>
265 #include <linux/err.h>
266 #include <linux/time.h>
267 #include <linux/slab.h>
268 #include <linux/errqueue.h>
269 #include <linux/static_key.h>
270 
271 #include <net/icmp.h>
272 #include <net/inet_common.h>
273 #include <net/tcp.h>
274 #include <net/mptcp.h>
275 #include <net/xfrm.h>
276 #include <net/ip.h>
277 #include <net/sock.h>
278 
279 #include <linux/uaccess.h>
280 #include <asm/ioctls.h>
281 #include <net/busy_poll.h>
282 
283 struct percpu_counter tcp_orphan_count;
284 EXPORT_SYMBOL_GPL(tcp_orphan_count);
285 
286 long sysctl_tcp_mem[3] __read_mostly;
287 EXPORT_SYMBOL(sysctl_tcp_mem);
288 
289 atomic_long_t tcp_memory_allocated;	/* Current allocated memory. */
290 EXPORT_SYMBOL(tcp_memory_allocated);
291 
292 #if IS_ENABLED(CONFIG_SMC)
293 DEFINE_STATIC_KEY_FALSE(tcp_have_smc);
294 EXPORT_SYMBOL(tcp_have_smc);
295 #endif
296 
297 /*
298  * Current number of TCP sockets.
299  */
300 struct percpu_counter tcp_sockets_allocated;
301 EXPORT_SYMBOL(tcp_sockets_allocated);
302 
303 /*
304  * TCP splice context
305  */
306 struct tcp_splice_state {
307 	struct pipe_inode_info *pipe;
308 	size_t len;
309 	unsigned int flags;
310 };
311 
312 /*
313  * Pressure flag: try to collapse.
314  * Technical note: it is used by multiple contexts non atomically.
315  * All the __sk_mem_schedule() is of this nature: accounting
316  * is strict, actions are advisory and have some latency.
317  */
318 unsigned long tcp_memory_pressure __read_mostly;
319 EXPORT_SYMBOL_GPL(tcp_memory_pressure);
320 
321 DEFINE_STATIC_KEY_FALSE(tcp_rx_skb_cache_key);
322 EXPORT_SYMBOL(tcp_rx_skb_cache_key);
323 
324 DEFINE_STATIC_KEY_FALSE(tcp_tx_skb_cache_key);
325 
326 void tcp_enter_memory_pressure(struct sock *sk)
327 {
328 	unsigned long val;
329 
330 	if (READ_ONCE(tcp_memory_pressure))
331 		return;
332 	val = jiffies;
333 
334 	if (!val)
335 		val--;
336 	if (!cmpxchg(&tcp_memory_pressure, 0, val))
337 		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMEMORYPRESSURES);
338 }
339 EXPORT_SYMBOL_GPL(tcp_enter_memory_pressure);
340 
341 void tcp_leave_memory_pressure(struct sock *sk)
342 {
343 	unsigned long val;
344 
345 	if (!READ_ONCE(tcp_memory_pressure))
346 		return;
347 	val = xchg(&tcp_memory_pressure, 0);
348 	if (val)
349 		NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPMEMORYPRESSURESCHRONO,
350 			      jiffies_to_msecs(jiffies - val));
351 }
352 EXPORT_SYMBOL_GPL(tcp_leave_memory_pressure);
353 
354 /* Convert seconds to retransmits based on initial and max timeout */
355 static u8 secs_to_retrans(int seconds, int timeout, int rto_max)
356 {
357 	u8 res = 0;
358 
359 	if (seconds > 0) {
360 		int period = timeout;
361 
362 		res = 1;
363 		while (seconds > period && res < 255) {
364 			res++;
365 			timeout <<= 1;
366 			if (timeout > rto_max)
367 				timeout = rto_max;
368 			period += timeout;
369 		}
370 	}
371 	return res;
372 }
373 
374 /* Convert retransmits to seconds based on initial and max timeout */
375 static int retrans_to_secs(u8 retrans, int timeout, int rto_max)
376 {
377 	int period = 0;
378 
379 	if (retrans > 0) {
380 		period = timeout;
381 		while (--retrans) {
382 			timeout <<= 1;
383 			if (timeout > rto_max)
384 				timeout = rto_max;
385 			period += timeout;
386 		}
387 	}
388 	return period;
389 }
390 
391 static u64 tcp_compute_delivery_rate(const struct tcp_sock *tp)
392 {
393 	u32 rate = READ_ONCE(tp->rate_delivered);
394 	u32 intv = READ_ONCE(tp->rate_interval_us);
395 	u64 rate64 = 0;
396 
397 	if (rate && intv) {
398 		rate64 = (u64)rate * tp->mss_cache * USEC_PER_SEC;
399 		do_div(rate64, intv);
400 	}
401 	return rate64;
402 }
403 
404 /* Address-family independent initialization for a tcp_sock.
405  *
406  * NOTE: A lot of things set to zero explicitly by call to
407  *       sk_alloc() so need not be done here.
408  */
409 void tcp_init_sock(struct sock *sk)
410 {
411 	struct inet_connection_sock *icsk = inet_csk(sk);
412 	struct tcp_sock *tp = tcp_sk(sk);
413 
414 	tp->out_of_order_queue = RB_ROOT;
415 	sk->tcp_rtx_queue = RB_ROOT;
416 	tcp_init_xmit_timers(sk);
417 	INIT_LIST_HEAD(&tp->tsq_node);
418 	INIT_LIST_HEAD(&tp->tsorted_sent_queue);
419 
420 	icsk->icsk_rto = TCP_TIMEOUT_INIT;
421 	icsk->icsk_rto_min = TCP_RTO_MIN;
422 	icsk->icsk_delack_max = TCP_DELACK_MAX;
423 	tp->mdev_us = jiffies_to_usecs(TCP_TIMEOUT_INIT);
424 	minmax_reset(&tp->rtt_min, tcp_jiffies32, ~0U);
425 
426 	/* So many TCP implementations out there (incorrectly) count the
427 	 * initial SYN frame in their delayed-ACK and congestion control
428 	 * algorithms that we must have the following bandaid to talk
429 	 * efficiently to them.  -DaveM
430 	 */
431 	tp->snd_cwnd = TCP_INIT_CWND;
432 
433 	/* There's a bubble in the pipe until at least the first ACK. */
434 	tp->app_limited = ~0U;
435 
436 	/* See draft-stevens-tcpca-spec-01 for discussion of the
437 	 * initialization of these values.
438 	 */
439 	tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
440 	tp->snd_cwnd_clamp = ~0;
441 	tp->mss_cache = TCP_MSS_DEFAULT;
442 
443 	tp->reordering = sock_net(sk)->ipv4.sysctl_tcp_reordering;
444 	tcp_assign_congestion_control(sk);
445 
446 	tp->tsoffset = 0;
447 	tp->rack.reo_wnd_steps = 1;
448 
449 	sk->sk_write_space = sk_stream_write_space;
450 	sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
451 
452 	icsk->icsk_sync_mss = tcp_sync_mss;
453 
454 	WRITE_ONCE(sk->sk_sndbuf, sock_net(sk)->ipv4.sysctl_tcp_wmem[1]);
455 	WRITE_ONCE(sk->sk_rcvbuf, sock_net(sk)->ipv4.sysctl_tcp_rmem[1]);
456 
457 	sk_sockets_allocated_inc(sk);
458 	sk->sk_route_forced_caps = NETIF_F_GSO;
459 }
460 EXPORT_SYMBOL(tcp_init_sock);
461 
462 static void tcp_tx_timestamp(struct sock *sk, u16 tsflags)
463 {
464 	struct sk_buff *skb = tcp_write_queue_tail(sk);
465 
466 	if (tsflags && skb) {
467 		struct skb_shared_info *shinfo = skb_shinfo(skb);
468 		struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
469 
470 		sock_tx_timestamp(sk, tsflags, &shinfo->tx_flags);
471 		if (tsflags & SOF_TIMESTAMPING_TX_ACK)
472 			tcb->txstamp_ack = 1;
473 		if (tsflags & SOF_TIMESTAMPING_TX_RECORD_MASK)
474 			shinfo->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;
475 	}
476 }
477 
478 static inline bool tcp_stream_is_readable(const struct tcp_sock *tp,
479 					  int target, struct sock *sk)
480 {
481 	int avail = READ_ONCE(tp->rcv_nxt) - READ_ONCE(tp->copied_seq);
482 
483 	if (avail > 0) {
484 		if (avail >= target)
485 			return true;
486 		if (tcp_rmem_pressure(sk))
487 			return true;
488 		if (tcp_receive_window(tp) <= inet_csk(sk)->icsk_ack.rcv_mss)
489 			return true;
490 	}
491 	if (sk->sk_prot->stream_memory_read)
492 		return sk->sk_prot->stream_memory_read(sk);
493 	return false;
494 }
495 
496 /*
497  *	Wait for a TCP event.
498  *
499  *	Note that we don't need to lock the socket, as the upper poll layers
500  *	take care of normal races (between the test and the event) and we don't
501  *	go look at any of the socket buffers directly.
502  */
503 __poll_t tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
504 {
505 	__poll_t mask;
506 	struct sock *sk = sock->sk;
507 	const struct tcp_sock *tp = tcp_sk(sk);
508 	int state;
509 
510 	sock_poll_wait(file, sock, wait);
511 
512 	state = inet_sk_state_load(sk);
513 	if (state == TCP_LISTEN)
514 		return inet_csk_listen_poll(sk);
515 
516 	/* Socket is not locked. We are protected from async events
517 	 * by poll logic and correct handling of state changes
518 	 * made by other threads is impossible in any case.
519 	 */
520 
521 	mask = 0;
522 
523 	/*
524 	 * EPOLLHUP is certainly not done right. But poll() doesn't
525 	 * have a notion of HUP in just one direction, and for a
526 	 * socket the read side is more interesting.
527 	 *
528 	 * Some poll() documentation says that EPOLLHUP is incompatible
529 	 * with the EPOLLOUT/POLLWR flags, so somebody should check this
530 	 * all. But careful, it tends to be safer to return too many
531 	 * bits than too few, and you can easily break real applications
532 	 * if you don't tell them that something has hung up!
533 	 *
534 	 * Check-me.
535 	 *
536 	 * Check number 1. EPOLLHUP is _UNMASKABLE_ event (see UNIX98 and
537 	 * our fs/select.c). It means that after we received EOF,
538 	 * poll always returns immediately, making impossible poll() on write()
539 	 * in state CLOSE_WAIT. One solution is evident --- to set EPOLLHUP
540 	 * if and only if shutdown has been made in both directions.
541 	 * Actually, it is interesting to look how Solaris and DUX
542 	 * solve this dilemma. I would prefer, if EPOLLHUP were maskable,
543 	 * then we could set it on SND_SHUTDOWN. BTW examples given
544 	 * in Stevens' books assume exactly this behaviour, it explains
545 	 * why EPOLLHUP is incompatible with EPOLLOUT.	--ANK
546 	 *
547 	 * NOTE. Check for TCP_CLOSE is added. The goal is to prevent
548 	 * blocking on fresh not-connected or disconnected socket. --ANK
549 	 */
550 	if (sk->sk_shutdown == SHUTDOWN_MASK || state == TCP_CLOSE)
551 		mask |= EPOLLHUP;
552 	if (sk->sk_shutdown & RCV_SHUTDOWN)
553 		mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP;
554 
555 	/* Connected or passive Fast Open socket? */
556 	if (state != TCP_SYN_SENT &&
557 	    (state != TCP_SYN_RECV || rcu_access_pointer(tp->fastopen_rsk))) {
558 		int target = sock_rcvlowat(sk, 0, INT_MAX);
559 
560 		if (READ_ONCE(tp->urg_seq) == READ_ONCE(tp->copied_seq) &&
561 		    !sock_flag(sk, SOCK_URGINLINE) &&
562 		    tp->urg_data)
563 			target++;
564 
565 		if (tcp_stream_is_readable(tp, target, sk))
566 			mask |= EPOLLIN | EPOLLRDNORM;
567 
568 		if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
569 			if (__sk_stream_is_writeable(sk, 1)) {
570 				mask |= EPOLLOUT | EPOLLWRNORM;
571 			} else {  /* send SIGIO later */
572 				sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
573 				set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
574 
575 				/* Race breaker. If space is freed after
576 				 * wspace test but before the flags are set,
577 				 * IO signal will be lost. Memory barrier
578 				 * pairs with the input side.
579 				 */
580 				smp_mb__after_atomic();
581 				if (__sk_stream_is_writeable(sk, 1))
582 					mask |= EPOLLOUT | EPOLLWRNORM;
583 			}
584 		} else
585 			mask |= EPOLLOUT | EPOLLWRNORM;
586 
587 		if (tp->urg_data & TCP_URG_VALID)
588 			mask |= EPOLLPRI;
589 	} else if (state == TCP_SYN_SENT && inet_sk(sk)->defer_connect) {
590 		/* Active TCP fastopen socket with defer_connect
591 		 * Return EPOLLOUT so application can call write()
592 		 * in order for kernel to generate SYN+data
593 		 */
594 		mask |= EPOLLOUT | EPOLLWRNORM;
595 	}
596 	/* This barrier is coupled with smp_wmb() in tcp_reset() */
597 	smp_rmb();
598 	if (sk->sk_err || !skb_queue_empty_lockless(&sk->sk_error_queue))
599 		mask |= EPOLLERR;
600 
601 	return mask;
602 }
603 EXPORT_SYMBOL(tcp_poll);
604 
605 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
606 {
607 	struct tcp_sock *tp = tcp_sk(sk);
608 	int answ;
609 	bool slow;
610 
611 	switch (cmd) {
612 	case SIOCINQ:
613 		if (sk->sk_state == TCP_LISTEN)
614 			return -EINVAL;
615 
616 		slow = lock_sock_fast(sk);
617 		answ = tcp_inq(sk);
618 		unlock_sock_fast(sk, slow);
619 		break;
620 	case SIOCATMARK:
621 		answ = tp->urg_data &&
622 		       READ_ONCE(tp->urg_seq) == READ_ONCE(tp->copied_seq);
623 		break;
624 	case SIOCOUTQ:
625 		if (sk->sk_state == TCP_LISTEN)
626 			return -EINVAL;
627 
628 		if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
629 			answ = 0;
630 		else
631 			answ = READ_ONCE(tp->write_seq) - tp->snd_una;
632 		break;
633 	case SIOCOUTQNSD:
634 		if (sk->sk_state == TCP_LISTEN)
635 			return -EINVAL;
636 
637 		if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
638 			answ = 0;
639 		else
640 			answ = READ_ONCE(tp->write_seq) -
641 			       READ_ONCE(tp->snd_nxt);
642 		break;
643 	default:
644 		return -ENOIOCTLCMD;
645 	}
646 
647 	return put_user(answ, (int __user *)arg);
648 }
649 EXPORT_SYMBOL(tcp_ioctl);
650 
651 static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
652 {
653 	TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH;
654 	tp->pushed_seq = tp->write_seq;
655 }
656 
657 static inline bool forced_push(const struct tcp_sock *tp)
658 {
659 	return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
660 }
661 
662 static void skb_entail(struct sock *sk, struct sk_buff *skb)
663 {
664 	struct tcp_sock *tp = tcp_sk(sk);
665 	struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
666 
667 	skb->csum    = 0;
668 	tcb->seq     = tcb->end_seq = tp->write_seq;
669 	tcb->tcp_flags = TCPHDR_ACK;
670 	tcb->sacked  = 0;
671 	__skb_header_release(skb);
672 	tcp_add_write_queue_tail(sk, skb);
673 	sk_wmem_queued_add(sk, skb->truesize);
674 	sk_mem_charge(sk, skb->truesize);
675 	if (tp->nonagle & TCP_NAGLE_PUSH)
676 		tp->nonagle &= ~TCP_NAGLE_PUSH;
677 
678 	tcp_slow_start_after_idle_check(sk);
679 }
680 
681 static inline void tcp_mark_urg(struct tcp_sock *tp, int flags)
682 {
683 	if (flags & MSG_OOB)
684 		tp->snd_up = tp->write_seq;
685 }
686 
687 /* If a not yet filled skb is pushed, do not send it if
688  * we have data packets in Qdisc or NIC queues :
689  * Because TX completion will happen shortly, it gives a chance
690  * to coalesce future sendmsg() payload into this skb, without
691  * need for a timer, and with no latency trade off.
692  * As packets containing data payload have a bigger truesize
693  * than pure acks (dataless) packets, the last checks prevent
694  * autocorking if we only have an ACK in Qdisc/NIC queues,
695  * or if TX completion was delayed after we processed ACK packet.
696  */
697 static bool tcp_should_autocork(struct sock *sk, struct sk_buff *skb,
698 				int size_goal)
699 {
700 	return skb->len < size_goal &&
701 	       sock_net(sk)->ipv4.sysctl_tcp_autocorking &&
702 	       !tcp_rtx_queue_empty(sk) &&
703 	       refcount_read(&sk->sk_wmem_alloc) > skb->truesize;
704 }
705 
706 void tcp_push(struct sock *sk, int flags, int mss_now,
707 	      int nonagle, int size_goal)
708 {
709 	struct tcp_sock *tp = tcp_sk(sk);
710 	struct sk_buff *skb;
711 
712 	skb = tcp_write_queue_tail(sk);
713 	if (!skb)
714 		return;
715 	if (!(flags & MSG_MORE) || forced_push(tp))
716 		tcp_mark_push(tp, skb);
717 
718 	tcp_mark_urg(tp, flags);
719 
720 	if (tcp_should_autocork(sk, skb, size_goal)) {
721 
722 		/* avoid atomic op if TSQ_THROTTLED bit is already set */
723 		if (!test_bit(TSQ_THROTTLED, &sk->sk_tsq_flags)) {
724 			NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAUTOCORKING);
725 			set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags);
726 		}
727 		/* It is possible TX completion already happened
728 		 * before we set TSQ_THROTTLED.
729 		 */
730 		if (refcount_read(&sk->sk_wmem_alloc) > skb->truesize)
731 			return;
732 	}
733 
734 	if (flags & MSG_MORE)
735 		nonagle = TCP_NAGLE_CORK;
736 
737 	__tcp_push_pending_frames(sk, mss_now, nonagle);
738 }
739 
740 static int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
741 				unsigned int offset, size_t len)
742 {
743 	struct tcp_splice_state *tss = rd_desc->arg.data;
744 	int ret;
745 
746 	ret = skb_splice_bits(skb, skb->sk, offset, tss->pipe,
747 			      min(rd_desc->count, len), tss->flags);
748 	if (ret > 0)
749 		rd_desc->count -= ret;
750 	return ret;
751 }
752 
753 static int __tcp_splice_read(struct sock *sk, struct tcp_splice_state *tss)
754 {
755 	/* Store TCP splice context information in read_descriptor_t. */
756 	read_descriptor_t rd_desc = {
757 		.arg.data = tss,
758 		.count	  = tss->len,
759 	};
760 
761 	return tcp_read_sock(sk, &rd_desc, tcp_splice_data_recv);
762 }
763 
764 /**
765  *  tcp_splice_read - splice data from TCP socket to a pipe
766  * @sock:	socket to splice from
767  * @ppos:	position (not valid)
768  * @pipe:	pipe to splice to
769  * @len:	number of bytes to splice
770  * @flags:	splice modifier flags
771  *
772  * Description:
773  *    Will read pages from given socket and fill them into a pipe.
774  *
775  **/
776 ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
777 			struct pipe_inode_info *pipe, size_t len,
778 			unsigned int flags)
779 {
780 	struct sock *sk = sock->sk;
781 	struct tcp_splice_state tss = {
782 		.pipe = pipe,
783 		.len = len,
784 		.flags = flags,
785 	};
786 	long timeo;
787 	ssize_t spliced;
788 	int ret;
789 
790 	sock_rps_record_flow(sk);
791 	/*
792 	 * We can't seek on a socket input
793 	 */
794 	if (unlikely(*ppos))
795 		return -ESPIPE;
796 
797 	ret = spliced = 0;
798 
799 	lock_sock(sk);
800 
801 	timeo = sock_rcvtimeo(sk, sock->file->f_flags & O_NONBLOCK);
802 	while (tss.len) {
803 		ret = __tcp_splice_read(sk, &tss);
804 		if (ret < 0)
805 			break;
806 		else if (!ret) {
807 			if (spliced)
808 				break;
809 			if (sock_flag(sk, SOCK_DONE))
810 				break;
811 			if (sk->sk_err) {
812 				ret = sock_error(sk);
813 				break;
814 			}
815 			if (sk->sk_shutdown & RCV_SHUTDOWN)
816 				break;
817 			if (sk->sk_state == TCP_CLOSE) {
818 				/*
819 				 * This occurs when user tries to read
820 				 * from never connected socket.
821 				 */
822 				ret = -ENOTCONN;
823 				break;
824 			}
825 			if (!timeo) {
826 				ret = -EAGAIN;
827 				break;
828 			}
829 			/* if __tcp_splice_read() got nothing while we have
830 			 * an skb in receive queue, we do not want to loop.
831 			 * This might happen with URG data.
832 			 */
833 			if (!skb_queue_empty(&sk->sk_receive_queue))
834 				break;
835 			sk_wait_data(sk, &timeo, NULL);
836 			if (signal_pending(current)) {
837 				ret = sock_intr_errno(timeo);
838 				break;
839 			}
840 			continue;
841 		}
842 		tss.len -= ret;
843 		spliced += ret;
844 
845 		if (!timeo)
846 			break;
847 		release_sock(sk);
848 		lock_sock(sk);
849 
850 		if (sk->sk_err || sk->sk_state == TCP_CLOSE ||
851 		    (sk->sk_shutdown & RCV_SHUTDOWN) ||
852 		    signal_pending(current))
853 			break;
854 	}
855 
856 	release_sock(sk);
857 
858 	if (spliced)
859 		return spliced;
860 
861 	return ret;
862 }
863 EXPORT_SYMBOL(tcp_splice_read);
864 
865 struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp,
866 				    bool force_schedule)
867 {
868 	struct sk_buff *skb;
869 
870 	if (likely(!size)) {
871 		skb = sk->sk_tx_skb_cache;
872 		if (skb) {
873 			skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
874 			sk->sk_tx_skb_cache = NULL;
875 			pskb_trim(skb, 0);
876 			INIT_LIST_HEAD(&skb->tcp_tsorted_anchor);
877 			skb_shinfo(skb)->tx_flags = 0;
878 			memset(TCP_SKB_CB(skb), 0, sizeof(struct tcp_skb_cb));
879 			return skb;
880 		}
881 	}
882 	/* The TCP header must be at least 32-bit aligned.  */
883 	size = ALIGN(size, 4);
884 
885 	if (unlikely(tcp_under_memory_pressure(sk)))
886 		sk_mem_reclaim_partial(sk);
887 
888 	skb = alloc_skb_fclone(size + sk->sk_prot->max_header, gfp);
889 	if (likely(skb)) {
890 		bool mem_scheduled;
891 
892 		if (force_schedule) {
893 			mem_scheduled = true;
894 			sk_forced_mem_schedule(sk, skb->truesize);
895 		} else {
896 			mem_scheduled = sk_wmem_schedule(sk, skb->truesize);
897 		}
898 		if (likely(mem_scheduled)) {
899 			skb_reserve(skb, sk->sk_prot->max_header);
900 			/*
901 			 * Make sure that we have exactly size bytes
902 			 * available to the caller, no more, no less.
903 			 */
904 			skb->reserved_tailroom = skb->end - skb->tail - size;
905 			INIT_LIST_HEAD(&skb->tcp_tsorted_anchor);
906 			return skb;
907 		}
908 		__kfree_skb(skb);
909 	} else {
910 		sk->sk_prot->enter_memory_pressure(sk);
911 		sk_stream_moderate_sndbuf(sk);
912 	}
913 	return NULL;
914 }
915 
916 static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now,
917 				       int large_allowed)
918 {
919 	struct tcp_sock *tp = tcp_sk(sk);
920 	u32 new_size_goal, size_goal;
921 
922 	if (!large_allowed)
923 		return mss_now;
924 
925 	/* Note : tcp_tso_autosize() will eventually split this later */
926 	new_size_goal = sk->sk_gso_max_size - 1 - MAX_TCP_HEADER;
927 	new_size_goal = tcp_bound_to_half_wnd(tp, new_size_goal);
928 
929 	/* We try hard to avoid divides here */
930 	size_goal = tp->gso_segs * mss_now;
931 	if (unlikely(new_size_goal < size_goal ||
932 		     new_size_goal >= size_goal + mss_now)) {
933 		tp->gso_segs = min_t(u16, new_size_goal / mss_now,
934 				     sk->sk_gso_max_segs);
935 		size_goal = tp->gso_segs * mss_now;
936 	}
937 
938 	return max(size_goal, mss_now);
939 }
940 
941 int tcp_send_mss(struct sock *sk, int *size_goal, int flags)
942 {
943 	int mss_now;
944 
945 	mss_now = tcp_current_mss(sk);
946 	*size_goal = tcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB));
947 
948 	return mss_now;
949 }
950 
951 /* In some cases, both sendpage() and sendmsg() could have added
952  * an skb to the write queue, but failed adding payload on it.
953  * We need to remove it to consume less memory, but more
954  * importantly be able to generate EPOLLOUT for Edge Trigger epoll()
955  * users.
956  */
957 void tcp_remove_empty_skb(struct sock *sk, struct sk_buff *skb)
958 {
959 	if (skb && !skb->len) {
960 		tcp_unlink_write_queue(skb, sk);
961 		if (tcp_write_queue_empty(sk))
962 			tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
963 		sk_wmem_free_skb(sk, skb);
964 	}
965 }
966 
967 struct sk_buff *tcp_build_frag(struct sock *sk, int size_goal, int flags,
968 			       struct page *page, int offset, size_t *size)
969 {
970 	struct sk_buff *skb = tcp_write_queue_tail(sk);
971 	struct tcp_sock *tp = tcp_sk(sk);
972 	bool can_coalesce;
973 	int copy, i;
974 
975 	if (!skb || (copy = size_goal - skb->len) <= 0 ||
976 	    !tcp_skb_can_collapse_to(skb)) {
977 new_segment:
978 		if (!sk_stream_memory_free(sk))
979 			return NULL;
980 
981 		skb = sk_stream_alloc_skb(sk, 0, sk->sk_allocation,
982 					  tcp_rtx_and_write_queues_empty(sk));
983 		if (!skb)
984 			return NULL;
985 
986 #ifdef CONFIG_TLS_DEVICE
987 		skb->decrypted = !!(flags & MSG_SENDPAGE_DECRYPTED);
988 #endif
989 		skb_entail(sk, skb);
990 		copy = size_goal;
991 	}
992 
993 	if (copy > *size)
994 		copy = *size;
995 
996 	i = skb_shinfo(skb)->nr_frags;
997 	can_coalesce = skb_can_coalesce(skb, i, page, offset);
998 	if (!can_coalesce && i >= sysctl_max_skb_frags) {
999 		tcp_mark_push(tp, skb);
1000 		goto new_segment;
1001 	}
1002 	if (!sk_wmem_schedule(sk, copy))
1003 		return NULL;
1004 
1005 	if (can_coalesce) {
1006 		skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1007 	} else {
1008 		get_page(page);
1009 		skb_fill_page_desc(skb, i, page, offset, copy);
1010 	}
1011 
1012 	if (!(flags & MSG_NO_SHARED_FRAGS))
1013 		skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
1014 
1015 	skb->len += copy;
1016 	skb->data_len += copy;
1017 	skb->truesize += copy;
1018 	sk_wmem_queued_add(sk, copy);
1019 	sk_mem_charge(sk, copy);
1020 	skb->ip_summed = CHECKSUM_PARTIAL;
1021 	WRITE_ONCE(tp->write_seq, tp->write_seq + copy);
1022 	TCP_SKB_CB(skb)->end_seq += copy;
1023 	tcp_skb_pcount_set(skb, 0);
1024 
1025 	*size = copy;
1026 	return skb;
1027 }
1028 
1029 ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
1030 			 size_t size, int flags)
1031 {
1032 	struct tcp_sock *tp = tcp_sk(sk);
1033 	int mss_now, size_goal;
1034 	int err;
1035 	ssize_t copied;
1036 	long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
1037 
1038 	if (IS_ENABLED(CONFIG_DEBUG_VM) &&
1039 	    WARN_ONCE(!sendpage_ok(page),
1040 		      "page must not be a Slab one and have page_count > 0"))
1041 		return -EINVAL;
1042 
1043 	/* Wait for a connection to finish. One exception is TCP Fast Open
1044 	 * (passive side) where data is allowed to be sent before a connection
1045 	 * is fully established.
1046 	 */
1047 	if (((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) &&
1048 	    !tcp_passive_fastopen(sk)) {
1049 		err = sk_stream_wait_connect(sk, &timeo);
1050 		if (err != 0)
1051 			goto out_err;
1052 	}
1053 
1054 	sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
1055 
1056 	mss_now = tcp_send_mss(sk, &size_goal, flags);
1057 	copied = 0;
1058 
1059 	err = -EPIPE;
1060 	if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
1061 		goto out_err;
1062 
1063 	while (size > 0) {
1064 		struct sk_buff *skb;
1065 		size_t copy = size;
1066 
1067 		skb = tcp_build_frag(sk, size_goal, flags, page, offset, &copy);
1068 		if (!skb)
1069 			goto wait_for_space;
1070 
1071 		if (!copied)
1072 			TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
1073 
1074 		copied += copy;
1075 		offset += copy;
1076 		size -= copy;
1077 		if (!size)
1078 			goto out;
1079 
1080 		if (skb->len < size_goal || (flags & MSG_OOB))
1081 			continue;
1082 
1083 		if (forced_push(tp)) {
1084 			tcp_mark_push(tp, skb);
1085 			__tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
1086 		} else if (skb == tcp_send_head(sk))
1087 			tcp_push_one(sk, mss_now);
1088 		continue;
1089 
1090 wait_for_space:
1091 		set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
1092 		tcp_push(sk, flags & ~MSG_MORE, mss_now,
1093 			 TCP_NAGLE_PUSH, size_goal);
1094 
1095 		err = sk_stream_wait_memory(sk, &timeo);
1096 		if (err != 0)
1097 			goto do_error;
1098 
1099 		mss_now = tcp_send_mss(sk, &size_goal, flags);
1100 	}
1101 
1102 out:
1103 	if (copied) {
1104 		tcp_tx_timestamp(sk, sk->sk_tsflags);
1105 		if (!(flags & MSG_SENDPAGE_NOTLAST))
1106 			tcp_push(sk, flags, mss_now, tp->nonagle, size_goal);
1107 	}
1108 	return copied;
1109 
1110 do_error:
1111 	tcp_remove_empty_skb(sk, tcp_write_queue_tail(sk));
1112 	if (copied)
1113 		goto out;
1114 out_err:
1115 	/* make sure we wake any epoll edge trigger waiter */
1116 	if (unlikely(tcp_rtx_and_write_queues_empty(sk) && err == -EAGAIN)) {
1117 		sk->sk_write_space(sk);
1118 		tcp_chrono_stop(sk, TCP_CHRONO_SNDBUF_LIMITED);
1119 	}
1120 	return sk_stream_error(sk, flags, err);
1121 }
1122 EXPORT_SYMBOL_GPL(do_tcp_sendpages);
1123 
1124 int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset,
1125 			size_t size, int flags)
1126 {
1127 	if (!(sk->sk_route_caps & NETIF_F_SG))
1128 		return sock_no_sendpage_locked(sk, page, offset, size, flags);
1129 
1130 	tcp_rate_check_app_limited(sk);  /* is sending application-limited? */
1131 
1132 	return do_tcp_sendpages(sk, page, offset, size, flags);
1133 }
1134 EXPORT_SYMBOL_GPL(tcp_sendpage_locked);
1135 
1136 int tcp_sendpage(struct sock *sk, struct page *page, int offset,
1137 		 size_t size, int flags)
1138 {
1139 	int ret;
1140 
1141 	lock_sock(sk);
1142 	ret = tcp_sendpage_locked(sk, page, offset, size, flags);
1143 	release_sock(sk);
1144 
1145 	return ret;
1146 }
1147 EXPORT_SYMBOL(tcp_sendpage);
1148 
1149 void tcp_free_fastopen_req(struct tcp_sock *tp)
1150 {
1151 	if (tp->fastopen_req) {
1152 		kfree(tp->fastopen_req);
1153 		tp->fastopen_req = NULL;
1154 	}
1155 }
1156 
1157 static int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg,
1158 				int *copied, size_t size,
1159 				struct ubuf_info *uarg)
1160 {
1161 	struct tcp_sock *tp = tcp_sk(sk);
1162 	struct inet_sock *inet = inet_sk(sk);
1163 	struct sockaddr *uaddr = msg->msg_name;
1164 	int err, flags;
1165 
1166 	if (!(sock_net(sk)->ipv4.sysctl_tcp_fastopen & TFO_CLIENT_ENABLE) ||
1167 	    (uaddr && msg->msg_namelen >= sizeof(uaddr->sa_family) &&
1168 	     uaddr->sa_family == AF_UNSPEC))
1169 		return -EOPNOTSUPP;
1170 	if (tp->fastopen_req)
1171 		return -EALREADY; /* Another Fast Open is in progress */
1172 
1173 	tp->fastopen_req = kzalloc(sizeof(struct tcp_fastopen_request),
1174 				   sk->sk_allocation);
1175 	if (unlikely(!tp->fastopen_req))
1176 		return -ENOBUFS;
1177 	tp->fastopen_req->data = msg;
1178 	tp->fastopen_req->size = size;
1179 	tp->fastopen_req->uarg = uarg;
1180 
1181 	if (inet->defer_connect) {
1182 		err = tcp_connect(sk);
1183 		/* Same failure procedure as in tcp_v4/6_connect */
1184 		if (err) {
1185 			tcp_set_state(sk, TCP_CLOSE);
1186 			inet->inet_dport = 0;
1187 			sk->sk_route_caps = 0;
1188 		}
1189 	}
1190 	flags = (msg->msg_flags & MSG_DONTWAIT) ? O_NONBLOCK : 0;
1191 	err = __inet_stream_connect(sk->sk_socket, uaddr,
1192 				    msg->msg_namelen, flags, 1);
1193 	/* fastopen_req could already be freed in __inet_stream_connect
1194 	 * if the connection times out or gets rst
1195 	 */
1196 	if (tp->fastopen_req) {
1197 		*copied = tp->fastopen_req->copied;
1198 		tcp_free_fastopen_req(tp);
1199 		inet->defer_connect = 0;
1200 	}
1201 	return err;
1202 }
1203 
1204 int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
1205 {
1206 	struct tcp_sock *tp = tcp_sk(sk);
1207 	struct ubuf_info *uarg = NULL;
1208 	struct sk_buff *skb;
1209 	struct sockcm_cookie sockc;
1210 	int flags, err, copied = 0;
1211 	int mss_now = 0, size_goal, copied_syn = 0;
1212 	int process_backlog = 0;
1213 	bool zc = false;
1214 	long timeo;
1215 
1216 	flags = msg->msg_flags;
1217 
1218 	if (flags & MSG_ZEROCOPY && size && sock_flag(sk, SOCK_ZEROCOPY)) {
1219 		skb = tcp_write_queue_tail(sk);
1220 		uarg = sock_zerocopy_realloc(sk, size, skb_zcopy(skb));
1221 		if (!uarg) {
1222 			err = -ENOBUFS;
1223 			goto out_err;
1224 		}
1225 
1226 		zc = sk->sk_route_caps & NETIF_F_SG;
1227 		if (!zc)
1228 			uarg->zerocopy = 0;
1229 	}
1230 
1231 	if (unlikely(flags & MSG_FASTOPEN || inet_sk(sk)->defer_connect) &&
1232 	    !tp->repair) {
1233 		err = tcp_sendmsg_fastopen(sk, msg, &copied_syn, size, uarg);
1234 		if (err == -EINPROGRESS && copied_syn > 0)
1235 			goto out;
1236 		else if (err)
1237 			goto out_err;
1238 	}
1239 
1240 	timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
1241 
1242 	tcp_rate_check_app_limited(sk);  /* is sending application-limited? */
1243 
1244 	/* Wait for a connection to finish. One exception is TCP Fast Open
1245 	 * (passive side) where data is allowed to be sent before a connection
1246 	 * is fully established.
1247 	 */
1248 	if (((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) &&
1249 	    !tcp_passive_fastopen(sk)) {
1250 		err = sk_stream_wait_connect(sk, &timeo);
1251 		if (err != 0)
1252 			goto do_error;
1253 	}
1254 
1255 	if (unlikely(tp->repair)) {
1256 		if (tp->repair_queue == TCP_RECV_QUEUE) {
1257 			copied = tcp_send_rcvq(sk, msg, size);
1258 			goto out_nopush;
1259 		}
1260 
1261 		err = -EINVAL;
1262 		if (tp->repair_queue == TCP_NO_QUEUE)
1263 			goto out_err;
1264 
1265 		/* 'common' sending to sendq */
1266 	}
1267 
1268 	sockcm_init(&sockc, sk);
1269 	if (msg->msg_controllen) {
1270 		err = sock_cmsg_send(sk, msg, &sockc);
1271 		if (unlikely(err)) {
1272 			err = -EINVAL;
1273 			goto out_err;
1274 		}
1275 	}
1276 
1277 	/* This should be in poll */
1278 	sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
1279 
1280 	/* Ok commence sending. */
1281 	copied = 0;
1282 
1283 restart:
1284 	mss_now = tcp_send_mss(sk, &size_goal, flags);
1285 
1286 	err = -EPIPE;
1287 	if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
1288 		goto do_error;
1289 
1290 	while (msg_data_left(msg)) {
1291 		int copy = 0;
1292 
1293 		skb = tcp_write_queue_tail(sk);
1294 		if (skb)
1295 			copy = size_goal - skb->len;
1296 
1297 		if (copy <= 0 || !tcp_skb_can_collapse_to(skb)) {
1298 			bool first_skb;
1299 
1300 new_segment:
1301 			if (!sk_stream_memory_free(sk))
1302 				goto wait_for_space;
1303 
1304 			if (unlikely(process_backlog >= 16)) {
1305 				process_backlog = 0;
1306 				if (sk_flush_backlog(sk))
1307 					goto restart;
1308 			}
1309 			first_skb = tcp_rtx_and_write_queues_empty(sk);
1310 			skb = sk_stream_alloc_skb(sk, 0, sk->sk_allocation,
1311 						  first_skb);
1312 			if (!skb)
1313 				goto wait_for_space;
1314 
1315 			process_backlog++;
1316 			skb->ip_summed = CHECKSUM_PARTIAL;
1317 
1318 			skb_entail(sk, skb);
1319 			copy = size_goal;
1320 
1321 			/* All packets are restored as if they have
1322 			 * already been sent. skb_mstamp_ns isn't set to
1323 			 * avoid wrong rtt estimation.
1324 			 */
1325 			if (tp->repair)
1326 				TCP_SKB_CB(skb)->sacked |= TCPCB_REPAIRED;
1327 		}
1328 
1329 		/* Try to append data to the end of skb. */
1330 		if (copy > msg_data_left(msg))
1331 			copy = msg_data_left(msg);
1332 
1333 		/* Where to copy to? */
1334 		if (skb_availroom(skb) > 0 && !zc) {
1335 			/* We have some space in skb head. Superb! */
1336 			copy = min_t(int, copy, skb_availroom(skb));
1337 			err = skb_add_data_nocache(sk, skb, &msg->msg_iter, copy);
1338 			if (err)
1339 				goto do_fault;
1340 		} else if (!zc) {
1341 			bool merge = true;
1342 			int i = skb_shinfo(skb)->nr_frags;
1343 			struct page_frag *pfrag = sk_page_frag(sk);
1344 
1345 			if (!sk_page_frag_refill(sk, pfrag))
1346 				goto wait_for_space;
1347 
1348 			if (!skb_can_coalesce(skb, i, pfrag->page,
1349 					      pfrag->offset)) {
1350 				if (i >= sysctl_max_skb_frags) {
1351 					tcp_mark_push(tp, skb);
1352 					goto new_segment;
1353 				}
1354 				merge = false;
1355 			}
1356 
1357 			copy = min_t(int, copy, pfrag->size - pfrag->offset);
1358 
1359 			if (!sk_wmem_schedule(sk, copy))
1360 				goto wait_for_space;
1361 
1362 			err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
1363 						       pfrag->page,
1364 						       pfrag->offset,
1365 						       copy);
1366 			if (err)
1367 				goto do_error;
1368 
1369 			/* Update the skb. */
1370 			if (merge) {
1371 				skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1372 			} else {
1373 				skb_fill_page_desc(skb, i, pfrag->page,
1374 						   pfrag->offset, copy);
1375 				page_ref_inc(pfrag->page);
1376 			}
1377 			pfrag->offset += copy;
1378 		} else {
1379 			err = skb_zerocopy_iter_stream(sk, skb, msg, copy, uarg);
1380 			if (err == -EMSGSIZE || err == -EEXIST) {
1381 				tcp_mark_push(tp, skb);
1382 				goto new_segment;
1383 			}
1384 			if (err < 0)
1385 				goto do_error;
1386 			copy = err;
1387 		}
1388 
1389 		if (!copied)
1390 			TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
1391 
1392 		WRITE_ONCE(tp->write_seq, tp->write_seq + copy);
1393 		TCP_SKB_CB(skb)->end_seq += copy;
1394 		tcp_skb_pcount_set(skb, 0);
1395 
1396 		copied += copy;
1397 		if (!msg_data_left(msg)) {
1398 			if (unlikely(flags & MSG_EOR))
1399 				TCP_SKB_CB(skb)->eor = 1;
1400 			goto out;
1401 		}
1402 
1403 		if (skb->len < size_goal || (flags & MSG_OOB) || unlikely(tp->repair))
1404 			continue;
1405 
1406 		if (forced_push(tp)) {
1407 			tcp_mark_push(tp, skb);
1408 			__tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
1409 		} else if (skb == tcp_send_head(sk))
1410 			tcp_push_one(sk, mss_now);
1411 		continue;
1412 
1413 wait_for_space:
1414 		set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
1415 		if (copied)
1416 			tcp_push(sk, flags & ~MSG_MORE, mss_now,
1417 				 TCP_NAGLE_PUSH, size_goal);
1418 
1419 		err = sk_stream_wait_memory(sk, &timeo);
1420 		if (err != 0)
1421 			goto do_error;
1422 
1423 		mss_now = tcp_send_mss(sk, &size_goal, flags);
1424 	}
1425 
1426 out:
1427 	if (copied) {
1428 		tcp_tx_timestamp(sk, sockc.tsflags);
1429 		tcp_push(sk, flags, mss_now, tp->nonagle, size_goal);
1430 	}
1431 out_nopush:
1432 	sock_zerocopy_put(uarg);
1433 	return copied + copied_syn;
1434 
1435 do_error:
1436 	skb = tcp_write_queue_tail(sk);
1437 do_fault:
1438 	tcp_remove_empty_skb(sk, skb);
1439 
1440 	if (copied + copied_syn)
1441 		goto out;
1442 out_err:
1443 	sock_zerocopy_put_abort(uarg, true);
1444 	err = sk_stream_error(sk, flags, err);
1445 	/* make sure we wake any epoll edge trigger waiter */
1446 	if (unlikely(tcp_rtx_and_write_queues_empty(sk) && err == -EAGAIN)) {
1447 		sk->sk_write_space(sk);
1448 		tcp_chrono_stop(sk, TCP_CHRONO_SNDBUF_LIMITED);
1449 	}
1450 	return err;
1451 }
1452 EXPORT_SYMBOL_GPL(tcp_sendmsg_locked);
1453 
1454 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
1455 {
1456 	int ret;
1457 
1458 	lock_sock(sk);
1459 	ret = tcp_sendmsg_locked(sk, msg, size);
1460 	release_sock(sk);
1461 
1462 	return ret;
1463 }
1464 EXPORT_SYMBOL(tcp_sendmsg);
1465 
1466 /*
1467  *	Handle reading urgent data. BSD has very simple semantics for
1468  *	this, no blocking and very strange errors 8)
1469  */
1470 
1471 static int tcp_recv_urg(struct sock *sk, struct msghdr *msg, int len, int flags)
1472 {
1473 	struct tcp_sock *tp = tcp_sk(sk);
1474 
1475 	/* No URG data to read. */
1476 	if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data ||
1477 	    tp->urg_data == TCP_URG_READ)
1478 		return -EINVAL;	/* Yes this is right ! */
1479 
1480 	if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE))
1481 		return -ENOTCONN;
1482 
1483 	if (tp->urg_data & TCP_URG_VALID) {
1484 		int err = 0;
1485 		char c = tp->urg_data;
1486 
1487 		if (!(flags & MSG_PEEK))
1488 			tp->urg_data = TCP_URG_READ;
1489 
1490 		/* Read urgent data. */
1491 		msg->msg_flags |= MSG_OOB;
1492 
1493 		if (len > 0) {
1494 			if (!(flags & MSG_TRUNC))
1495 				err = memcpy_to_msg(msg, &c, 1);
1496 			len = 1;
1497 		} else
1498 			msg->msg_flags |= MSG_TRUNC;
1499 
1500 		return err ? -EFAULT : len;
1501 	}
1502 
1503 	if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
1504 		return 0;
1505 
1506 	/* Fixed the recv(..., MSG_OOB) behaviour.  BSD docs and
1507 	 * the available implementations agree in this case:
1508 	 * this call should never block, independent of the
1509 	 * blocking state of the socket.
1510 	 * Mike <pall@rz.uni-karlsruhe.de>
1511 	 */
1512 	return -EAGAIN;
1513 }
1514 
1515 static int tcp_peek_sndq(struct sock *sk, struct msghdr *msg, int len)
1516 {
1517 	struct sk_buff *skb;
1518 	int copied = 0, err = 0;
1519 
1520 	/* XXX -- need to support SO_PEEK_OFF */
1521 
1522 	skb_rbtree_walk(skb, &sk->tcp_rtx_queue) {
1523 		err = skb_copy_datagram_msg(skb, 0, msg, skb->len);
1524 		if (err)
1525 			return err;
1526 		copied += skb->len;
1527 	}
1528 
1529 	skb_queue_walk(&sk->sk_write_queue, skb) {
1530 		err = skb_copy_datagram_msg(skb, 0, msg, skb->len);
1531 		if (err)
1532 			break;
1533 
1534 		copied += skb->len;
1535 	}
1536 
1537 	return err ?: copied;
1538 }
1539 
1540 /* Clean up the receive buffer for full frames taken by the user,
1541  * then send an ACK if necessary.  COPIED is the number of bytes
1542  * tcp_recvmsg has given to the user so far, it speeds up the
1543  * calculation of whether or not we must ACK for the sake of
1544  * a window update.
1545  */
1546 void tcp_cleanup_rbuf(struct sock *sk, int copied)
1547 {
1548 	struct tcp_sock *tp = tcp_sk(sk);
1549 	bool time_to_ack = false;
1550 
1551 	struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
1552 
1553 	WARN(skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq),
1554 	     "cleanup rbuf bug: copied %X seq %X rcvnxt %X\n",
1555 	     tp->copied_seq, TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt);
1556 
1557 	if (inet_csk_ack_scheduled(sk)) {
1558 		const struct inet_connection_sock *icsk = inet_csk(sk);
1559 
1560 		if (/* Once-per-two-segments ACK was not sent by tcp_input.c */
1561 		    tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
1562 		    /*
1563 		     * If this read emptied read buffer, we send ACK, if
1564 		     * connection is not bidirectional, user drained
1565 		     * receive buffer and there was a small segment
1566 		     * in queue.
1567 		     */
1568 		    (copied > 0 &&
1569 		     ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED2) ||
1570 		      ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
1571 		       !inet_csk_in_pingpong_mode(sk))) &&
1572 		      !atomic_read(&sk->sk_rmem_alloc)))
1573 			time_to_ack = true;
1574 	}
1575 
1576 	/* We send an ACK if we can now advertise a non-zero window
1577 	 * which has been raised "significantly".
1578 	 *
1579 	 * Even if window raised up to infinity, do not send window open ACK
1580 	 * in states, where we will not receive more. It is useless.
1581 	 */
1582 	if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
1583 		__u32 rcv_window_now = tcp_receive_window(tp);
1584 
1585 		/* Optimize, __tcp_select_window() is not cheap. */
1586 		if (2*rcv_window_now <= tp->window_clamp) {
1587 			__u32 new_window = __tcp_select_window(sk);
1588 
1589 			/* Send ACK now, if this read freed lots of space
1590 			 * in our buffer. Certainly, new_window is new window.
1591 			 * We can advertise it now, if it is not less than current one.
1592 			 * "Lots" means "at least twice" here.
1593 			 */
1594 			if (new_window && new_window >= 2 * rcv_window_now)
1595 				time_to_ack = true;
1596 		}
1597 	}
1598 	if (time_to_ack)
1599 		tcp_send_ack(sk);
1600 }
1601 
1602 static struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
1603 {
1604 	struct sk_buff *skb;
1605 	u32 offset;
1606 
1607 	while ((skb = skb_peek(&sk->sk_receive_queue)) != NULL) {
1608 		offset = seq - TCP_SKB_CB(skb)->seq;
1609 		if (unlikely(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
1610 			pr_err_once("%s: found a SYN, please report !\n", __func__);
1611 			offset--;
1612 		}
1613 		if (offset < skb->len || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) {
1614 			*off = offset;
1615 			return skb;
1616 		}
1617 		/* This looks weird, but this can happen if TCP collapsing
1618 		 * splitted a fat GRO packet, while we released socket lock
1619 		 * in skb_splice_bits()
1620 		 */
1621 		sk_eat_skb(sk, skb);
1622 	}
1623 	return NULL;
1624 }
1625 
1626 /*
1627  * This routine provides an alternative to tcp_recvmsg() for routines
1628  * that would like to handle copying from skbuffs directly in 'sendfile'
1629  * fashion.
1630  * Note:
1631  *	- It is assumed that the socket was locked by the caller.
1632  *	- The routine does not block.
1633  *	- At present, there is no support for reading OOB data
1634  *	  or for 'peeking' the socket using this routine
1635  *	  (although both would be easy to implement).
1636  */
1637 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
1638 		  sk_read_actor_t recv_actor)
1639 {
1640 	struct sk_buff *skb;
1641 	struct tcp_sock *tp = tcp_sk(sk);
1642 	u32 seq = tp->copied_seq;
1643 	u32 offset;
1644 	int copied = 0;
1645 
1646 	if (sk->sk_state == TCP_LISTEN)
1647 		return -ENOTCONN;
1648 	while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
1649 		if (offset < skb->len) {
1650 			int used;
1651 			size_t len;
1652 
1653 			len = skb->len - offset;
1654 			/* Stop reading if we hit a patch of urgent data */
1655 			if (tp->urg_data) {
1656 				u32 urg_offset = tp->urg_seq - seq;
1657 				if (urg_offset < len)
1658 					len = urg_offset;
1659 				if (!len)
1660 					break;
1661 			}
1662 			used = recv_actor(desc, skb, offset, len);
1663 			if (used <= 0) {
1664 				if (!copied)
1665 					copied = used;
1666 				break;
1667 			} else if (used <= len) {
1668 				seq += used;
1669 				copied += used;
1670 				offset += used;
1671 			}
1672 			/* If recv_actor drops the lock (e.g. TCP splice
1673 			 * receive) the skb pointer might be invalid when
1674 			 * getting here: tcp_collapse might have deleted it
1675 			 * while aggregating skbs from the socket queue.
1676 			 */
1677 			skb = tcp_recv_skb(sk, seq - 1, &offset);
1678 			if (!skb)
1679 				break;
1680 			/* TCP coalescing might have appended data to the skb.
1681 			 * Try to splice more frags
1682 			 */
1683 			if (offset + 1 != skb->len)
1684 				continue;
1685 		}
1686 		if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) {
1687 			sk_eat_skb(sk, skb);
1688 			++seq;
1689 			break;
1690 		}
1691 		sk_eat_skb(sk, skb);
1692 		if (!desc->count)
1693 			break;
1694 		WRITE_ONCE(tp->copied_seq, seq);
1695 	}
1696 	WRITE_ONCE(tp->copied_seq, seq);
1697 
1698 	tcp_rcv_space_adjust(sk);
1699 
1700 	/* Clean up data we have read: This will do ACK frames. */
1701 	if (copied > 0) {
1702 		tcp_recv_skb(sk, seq, &offset);
1703 		tcp_cleanup_rbuf(sk, copied);
1704 	}
1705 	return copied;
1706 }
1707 EXPORT_SYMBOL(tcp_read_sock);
1708 
1709 int tcp_peek_len(struct socket *sock)
1710 {
1711 	return tcp_inq(sock->sk);
1712 }
1713 EXPORT_SYMBOL(tcp_peek_len);
1714 
1715 /* Make sure sk_rcvbuf is big enough to satisfy SO_RCVLOWAT hint */
1716 int tcp_set_rcvlowat(struct sock *sk, int val)
1717 {
1718 	int cap;
1719 
1720 	if (sk->sk_userlocks & SOCK_RCVBUF_LOCK)
1721 		cap = sk->sk_rcvbuf >> 1;
1722 	else
1723 		cap = sock_net(sk)->ipv4.sysctl_tcp_rmem[2] >> 1;
1724 	val = min(val, cap);
1725 	WRITE_ONCE(sk->sk_rcvlowat, val ? : 1);
1726 
1727 	/* Check if we need to signal EPOLLIN right now */
1728 	tcp_data_ready(sk);
1729 
1730 	if (sk->sk_userlocks & SOCK_RCVBUF_LOCK)
1731 		return 0;
1732 
1733 	val <<= 1;
1734 	if (val > sk->sk_rcvbuf) {
1735 		WRITE_ONCE(sk->sk_rcvbuf, val);
1736 		tcp_sk(sk)->window_clamp = tcp_win_from_space(sk, val);
1737 	}
1738 	return 0;
1739 }
1740 EXPORT_SYMBOL(tcp_set_rcvlowat);
1741 
1742 #ifdef CONFIG_MMU
1743 static const struct vm_operations_struct tcp_vm_ops = {
1744 };
1745 
1746 int tcp_mmap(struct file *file, struct socket *sock,
1747 	     struct vm_area_struct *vma)
1748 {
1749 	if (vma->vm_flags & (VM_WRITE | VM_EXEC))
1750 		return -EPERM;
1751 	vma->vm_flags &= ~(VM_MAYWRITE | VM_MAYEXEC);
1752 
1753 	/* Instruct vm_insert_page() to not mmap_read_lock(mm) */
1754 	vma->vm_flags |= VM_MIXEDMAP;
1755 
1756 	vma->vm_ops = &tcp_vm_ops;
1757 	return 0;
1758 }
1759 EXPORT_SYMBOL(tcp_mmap);
1760 
1761 static skb_frag_t *skb_advance_to_frag(struct sk_buff *skb, u32 offset_skb,
1762 				       u32 *offset_frag)
1763 {
1764 	skb_frag_t *frag;
1765 
1766 	offset_skb -= skb_headlen(skb);
1767 	if ((int)offset_skb < 0 || skb_has_frag_list(skb))
1768 		return NULL;
1769 
1770 	frag = skb_shinfo(skb)->frags;
1771 	while (offset_skb) {
1772 		if (skb_frag_size(frag) > offset_skb) {
1773 			*offset_frag = offset_skb;
1774 			return frag;
1775 		}
1776 		offset_skb -= skb_frag_size(frag);
1777 		++frag;
1778 	}
1779 	*offset_frag = 0;
1780 	return frag;
1781 }
1782 
1783 static bool can_map_frag(const skb_frag_t *frag)
1784 {
1785 	return skb_frag_size(frag) == PAGE_SIZE && !skb_frag_off(frag);
1786 }
1787 
1788 static int find_next_mappable_frag(const skb_frag_t *frag,
1789 				   int remaining_in_skb)
1790 {
1791 	int offset = 0;
1792 
1793 	if (likely(can_map_frag(frag)))
1794 		return 0;
1795 
1796 	while (offset < remaining_in_skb && !can_map_frag(frag)) {
1797 		offset += skb_frag_size(frag);
1798 		++frag;
1799 	}
1800 	return offset;
1801 }
1802 
1803 static void tcp_zerocopy_set_hint_for_skb(struct sock *sk,
1804 					  struct tcp_zerocopy_receive *zc,
1805 					  struct sk_buff *skb, u32 offset)
1806 {
1807 	u32 frag_offset, partial_frag_remainder = 0;
1808 	int mappable_offset;
1809 	skb_frag_t *frag;
1810 
1811 	/* worst case: skip to next skb. try to improve on this case below */
1812 	zc->recv_skip_hint = skb->len - offset;
1813 
1814 	/* Find the frag containing this offset (and how far into that frag) */
1815 	frag = skb_advance_to_frag(skb, offset, &frag_offset);
1816 	if (!frag)
1817 		return;
1818 
1819 	if (frag_offset) {
1820 		struct skb_shared_info *info = skb_shinfo(skb);
1821 
1822 		/* We read part of the last frag, must recvmsg() rest of skb. */
1823 		if (frag == &info->frags[info->nr_frags - 1])
1824 			return;
1825 
1826 		/* Else, we must at least read the remainder in this frag. */
1827 		partial_frag_remainder = skb_frag_size(frag) - frag_offset;
1828 		zc->recv_skip_hint -= partial_frag_remainder;
1829 		++frag;
1830 	}
1831 
1832 	/* partial_frag_remainder: If part way through a frag, must read rest.
1833 	 * mappable_offset: Bytes till next mappable frag, *not* counting bytes
1834 	 * in partial_frag_remainder.
1835 	 */
1836 	mappable_offset = find_next_mappable_frag(frag, zc->recv_skip_hint);
1837 	zc->recv_skip_hint = mappable_offset + partial_frag_remainder;
1838 }
1839 
1840 static int tcp_recvmsg_locked(struct sock *sk, struct msghdr *msg, size_t len,
1841 			      int nonblock, int flags,
1842 			      struct scm_timestamping_internal *tss,
1843 			      int *cmsg_flags);
1844 static int receive_fallback_to_copy(struct sock *sk,
1845 				    struct tcp_zerocopy_receive *zc, int inq)
1846 {
1847 	unsigned long copy_address = (unsigned long)zc->copybuf_address;
1848 	struct scm_timestamping_internal tss_unused;
1849 	int err, cmsg_flags_unused;
1850 	struct msghdr msg = {};
1851 	struct iovec iov;
1852 
1853 	zc->length = 0;
1854 	zc->recv_skip_hint = 0;
1855 
1856 	if (copy_address != zc->copybuf_address)
1857 		return -EINVAL;
1858 
1859 	err = import_single_range(READ, (void __user *)copy_address,
1860 				  inq, &iov, &msg.msg_iter);
1861 	if (err)
1862 		return err;
1863 
1864 	err = tcp_recvmsg_locked(sk, &msg, inq, /*nonblock=*/1, /*flags=*/0,
1865 				 &tss_unused, &cmsg_flags_unused);
1866 	if (err < 0)
1867 		return err;
1868 
1869 	zc->copybuf_len = err;
1870 	if (likely(zc->copybuf_len)) {
1871 		struct sk_buff *skb;
1872 		u32 offset;
1873 
1874 		skb = tcp_recv_skb(sk, tcp_sk(sk)->copied_seq, &offset);
1875 		if (skb)
1876 			tcp_zerocopy_set_hint_for_skb(sk, zc, skb, offset);
1877 	}
1878 	return 0;
1879 }
1880 
1881 static int tcp_copy_straggler_data(struct tcp_zerocopy_receive *zc,
1882 				   struct sk_buff *skb, u32 copylen,
1883 				   u32 *offset, u32 *seq)
1884 {
1885 	unsigned long copy_address = (unsigned long)zc->copybuf_address;
1886 	struct msghdr msg = {};
1887 	struct iovec iov;
1888 	int err;
1889 
1890 	if (copy_address != zc->copybuf_address)
1891 		return -EINVAL;
1892 
1893 	err = import_single_range(READ, (void __user *)copy_address,
1894 				  copylen, &iov, &msg.msg_iter);
1895 	if (err)
1896 		return err;
1897 	err = skb_copy_datagram_msg(skb, *offset, &msg, copylen);
1898 	if (err)
1899 		return err;
1900 	zc->recv_skip_hint -= copylen;
1901 	*offset += copylen;
1902 	*seq += copylen;
1903 	return (__s32)copylen;
1904 }
1905 
1906 static int tcp_zerocopy_handle_leftover_data(struct tcp_zerocopy_receive *zc,
1907 					     struct sock *sk,
1908 					     struct sk_buff *skb,
1909 					     u32 *seq,
1910 					     s32 copybuf_len)
1911 {
1912 	u32 offset, copylen = min_t(u32, copybuf_len, zc->recv_skip_hint);
1913 
1914 	if (!copylen)
1915 		return 0;
1916 	/* skb is null if inq < PAGE_SIZE. */
1917 	if (skb)
1918 		offset = *seq - TCP_SKB_CB(skb)->seq;
1919 	else
1920 		skb = tcp_recv_skb(sk, *seq, &offset);
1921 
1922 	zc->copybuf_len = tcp_copy_straggler_data(zc, skb, copylen, &offset,
1923 						  seq);
1924 	return zc->copybuf_len < 0 ? 0 : copylen;
1925 }
1926 
1927 static int tcp_zerocopy_vm_insert_batch_error(struct vm_area_struct *vma,
1928 					      struct page **pending_pages,
1929 					      unsigned long pages_remaining,
1930 					      unsigned long *address,
1931 					      u32 *length,
1932 					      u32 *seq,
1933 					      struct tcp_zerocopy_receive *zc,
1934 					      u32 total_bytes_to_map,
1935 					      int err)
1936 {
1937 	/* At least one page did not map. Try zapping if we skipped earlier. */
1938 	if (err == -EBUSY &&
1939 	    zc->flags & TCP_RECEIVE_ZEROCOPY_FLAG_TLB_CLEAN_HINT) {
1940 		u32 maybe_zap_len;
1941 
1942 		maybe_zap_len = total_bytes_to_map -  /* All bytes to map */
1943 				*length + /* Mapped or pending */
1944 				(pages_remaining * PAGE_SIZE); /* Failed map. */
1945 		zap_page_range(vma, *address, maybe_zap_len);
1946 		err = 0;
1947 	}
1948 
1949 	if (!err) {
1950 		unsigned long leftover_pages = pages_remaining;
1951 		int bytes_mapped;
1952 
1953 		/* We called zap_page_range, try to reinsert. */
1954 		err = vm_insert_pages(vma, *address,
1955 				      pending_pages,
1956 				      &pages_remaining);
1957 		bytes_mapped = PAGE_SIZE * (leftover_pages - pages_remaining);
1958 		*seq += bytes_mapped;
1959 		*address += bytes_mapped;
1960 	}
1961 	if (err) {
1962 		/* Either we were unable to zap, OR we zapped, retried an
1963 		 * insert, and still had an issue. Either ways, pages_remaining
1964 		 * is the number of pages we were unable to map, and we unroll
1965 		 * some state we speculatively touched before.
1966 		 */
1967 		const int bytes_not_mapped = PAGE_SIZE * pages_remaining;
1968 
1969 		*length -= bytes_not_mapped;
1970 		zc->recv_skip_hint += bytes_not_mapped;
1971 	}
1972 	return err;
1973 }
1974 
1975 static int tcp_zerocopy_vm_insert_batch(struct vm_area_struct *vma,
1976 					struct page **pages,
1977 					unsigned int pages_to_map,
1978 					unsigned long *address,
1979 					u32 *length,
1980 					u32 *seq,
1981 					struct tcp_zerocopy_receive *zc,
1982 					u32 total_bytes_to_map)
1983 {
1984 	unsigned long pages_remaining = pages_to_map;
1985 	unsigned int pages_mapped;
1986 	unsigned int bytes_mapped;
1987 	int err;
1988 
1989 	err = vm_insert_pages(vma, *address, pages, &pages_remaining);
1990 	pages_mapped = pages_to_map - (unsigned int)pages_remaining;
1991 	bytes_mapped = PAGE_SIZE * pages_mapped;
1992 	/* Even if vm_insert_pages fails, it may have partially succeeded in
1993 	 * mapping (some but not all of the pages).
1994 	 */
1995 	*seq += bytes_mapped;
1996 	*address += bytes_mapped;
1997 
1998 	if (likely(!err))
1999 		return 0;
2000 
2001 	/* Error: maybe zap and retry + rollback state for failed inserts. */
2002 	return tcp_zerocopy_vm_insert_batch_error(vma, pages + pages_mapped,
2003 		pages_remaining, address, length, seq, zc, total_bytes_to_map,
2004 		err);
2005 }
2006 
2007 #define TCP_ZEROCOPY_PAGE_BATCH_SIZE 32
2008 static int tcp_zerocopy_receive(struct sock *sk,
2009 				struct tcp_zerocopy_receive *zc)
2010 {
2011 	u32 length = 0, offset, vma_len, avail_len, copylen = 0;
2012 	unsigned long address = (unsigned long)zc->address;
2013 	struct page *pages[TCP_ZEROCOPY_PAGE_BATCH_SIZE];
2014 	s32 copybuf_len = zc->copybuf_len;
2015 	struct tcp_sock *tp = tcp_sk(sk);
2016 	const skb_frag_t *frags = NULL;
2017 	unsigned int pages_to_map = 0;
2018 	struct vm_area_struct *vma;
2019 	struct sk_buff *skb = NULL;
2020 	u32 seq = tp->copied_seq;
2021 	u32 total_bytes_to_map;
2022 	int inq = tcp_inq(sk);
2023 	int ret;
2024 
2025 	zc->copybuf_len = 0;
2026 
2027 	if (address & (PAGE_SIZE - 1) || address != zc->address)
2028 		return -EINVAL;
2029 
2030 	if (sk->sk_state == TCP_LISTEN)
2031 		return -ENOTCONN;
2032 
2033 	sock_rps_record_flow(sk);
2034 
2035 	if (inq && inq <= copybuf_len)
2036 		return receive_fallback_to_copy(sk, zc, inq);
2037 
2038 	if (inq < PAGE_SIZE) {
2039 		zc->length = 0;
2040 		zc->recv_skip_hint = inq;
2041 		if (!inq && sock_flag(sk, SOCK_DONE))
2042 			return -EIO;
2043 		return 0;
2044 	}
2045 
2046 	mmap_read_lock(current->mm);
2047 
2048 	vma = find_vma(current->mm, address);
2049 	if (!vma || vma->vm_start > address || vma->vm_ops != &tcp_vm_ops) {
2050 		mmap_read_unlock(current->mm);
2051 		return -EINVAL;
2052 	}
2053 	vma_len = min_t(unsigned long, zc->length, vma->vm_end - address);
2054 	avail_len = min_t(u32, vma_len, inq);
2055 	total_bytes_to_map = avail_len & ~(PAGE_SIZE - 1);
2056 	if (total_bytes_to_map) {
2057 		if (!(zc->flags & TCP_RECEIVE_ZEROCOPY_FLAG_TLB_CLEAN_HINT))
2058 			zap_page_range(vma, address, total_bytes_to_map);
2059 		zc->length = total_bytes_to_map;
2060 		zc->recv_skip_hint = 0;
2061 	} else {
2062 		zc->length = avail_len;
2063 		zc->recv_skip_hint = avail_len;
2064 	}
2065 	ret = 0;
2066 	while (length + PAGE_SIZE <= zc->length) {
2067 		int mappable_offset;
2068 		struct page *page;
2069 
2070 		if (zc->recv_skip_hint < PAGE_SIZE) {
2071 			u32 offset_frag;
2072 
2073 			if (skb) {
2074 				if (zc->recv_skip_hint > 0)
2075 					break;
2076 				skb = skb->next;
2077 				offset = seq - TCP_SKB_CB(skb)->seq;
2078 			} else {
2079 				skb = tcp_recv_skb(sk, seq, &offset);
2080 			}
2081 			zc->recv_skip_hint = skb->len - offset;
2082 			frags = skb_advance_to_frag(skb, offset, &offset_frag);
2083 			if (!frags || offset_frag)
2084 				break;
2085 		}
2086 
2087 		mappable_offset = find_next_mappable_frag(frags,
2088 							  zc->recv_skip_hint);
2089 		if (mappable_offset) {
2090 			zc->recv_skip_hint = mappable_offset;
2091 			break;
2092 		}
2093 		page = skb_frag_page(frags);
2094 		prefetchw(page);
2095 		pages[pages_to_map++] = page;
2096 		length += PAGE_SIZE;
2097 		zc->recv_skip_hint -= PAGE_SIZE;
2098 		frags++;
2099 		if (pages_to_map == TCP_ZEROCOPY_PAGE_BATCH_SIZE ||
2100 		    zc->recv_skip_hint < PAGE_SIZE) {
2101 			/* Either full batch, or we're about to go to next skb
2102 			 * (and we cannot unroll failed ops across skbs).
2103 			 */
2104 			ret = tcp_zerocopy_vm_insert_batch(vma, pages,
2105 							   pages_to_map,
2106 							   &address, &length,
2107 							   &seq, zc,
2108 							   total_bytes_to_map);
2109 			if (ret)
2110 				goto out;
2111 			pages_to_map = 0;
2112 		}
2113 	}
2114 	if (pages_to_map) {
2115 		ret = tcp_zerocopy_vm_insert_batch(vma, pages, pages_to_map,
2116 						   &address, &length, &seq,
2117 						   zc, total_bytes_to_map);
2118 	}
2119 out:
2120 	mmap_read_unlock(current->mm);
2121 	/* Try to copy straggler data. */
2122 	if (!ret)
2123 		copylen = tcp_zerocopy_handle_leftover_data(zc, sk, skb, &seq,
2124 							    copybuf_len);
2125 
2126 	if (length + copylen) {
2127 		WRITE_ONCE(tp->copied_seq, seq);
2128 		tcp_rcv_space_adjust(sk);
2129 
2130 		/* Clean up data we have read: This will do ACK frames. */
2131 		tcp_recv_skb(sk, seq, &offset);
2132 		tcp_cleanup_rbuf(sk, length + copylen);
2133 		ret = 0;
2134 		if (length == zc->length)
2135 			zc->recv_skip_hint = 0;
2136 	} else {
2137 		if (!zc->recv_skip_hint && sock_flag(sk, SOCK_DONE))
2138 			ret = -EIO;
2139 	}
2140 	zc->length = length;
2141 	return ret;
2142 }
2143 #endif
2144 
2145 static void tcp_update_recv_tstamps(struct sk_buff *skb,
2146 				    struct scm_timestamping_internal *tss)
2147 {
2148 	if (skb->tstamp)
2149 		tss->ts[0] = ktime_to_timespec64(skb->tstamp);
2150 	else
2151 		tss->ts[0] = (struct timespec64) {0};
2152 
2153 	if (skb_hwtstamps(skb)->hwtstamp)
2154 		tss->ts[2] = ktime_to_timespec64(skb_hwtstamps(skb)->hwtstamp);
2155 	else
2156 		tss->ts[2] = (struct timespec64) {0};
2157 }
2158 
2159 /* Similar to __sock_recv_timestamp, but does not require an skb */
2160 static void tcp_recv_timestamp(struct msghdr *msg, const struct sock *sk,
2161 			       struct scm_timestamping_internal *tss)
2162 {
2163 	int new_tstamp = sock_flag(sk, SOCK_TSTAMP_NEW);
2164 	bool has_timestamping = false;
2165 
2166 	if (tss->ts[0].tv_sec || tss->ts[0].tv_nsec) {
2167 		if (sock_flag(sk, SOCK_RCVTSTAMP)) {
2168 			if (sock_flag(sk, SOCK_RCVTSTAMPNS)) {
2169 				if (new_tstamp) {
2170 					struct __kernel_timespec kts = {
2171 						.tv_sec = tss->ts[0].tv_sec,
2172 						.tv_nsec = tss->ts[0].tv_nsec,
2173 					};
2174 					put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPNS_NEW,
2175 						 sizeof(kts), &kts);
2176 				} else {
2177 					struct __kernel_old_timespec ts_old = {
2178 						.tv_sec = tss->ts[0].tv_sec,
2179 						.tv_nsec = tss->ts[0].tv_nsec,
2180 					};
2181 					put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPNS_OLD,
2182 						 sizeof(ts_old), &ts_old);
2183 				}
2184 			} else {
2185 				if (new_tstamp) {
2186 					struct __kernel_sock_timeval stv = {
2187 						.tv_sec = tss->ts[0].tv_sec,
2188 						.tv_usec = tss->ts[0].tv_nsec / 1000,
2189 					};
2190 					put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMP_NEW,
2191 						 sizeof(stv), &stv);
2192 				} else {
2193 					struct __kernel_old_timeval tv = {
2194 						.tv_sec = tss->ts[0].tv_sec,
2195 						.tv_usec = tss->ts[0].tv_nsec / 1000,
2196 					};
2197 					put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMP_OLD,
2198 						 sizeof(tv), &tv);
2199 				}
2200 			}
2201 		}
2202 
2203 		if (sk->sk_tsflags & SOF_TIMESTAMPING_SOFTWARE)
2204 			has_timestamping = true;
2205 		else
2206 			tss->ts[0] = (struct timespec64) {0};
2207 	}
2208 
2209 	if (tss->ts[2].tv_sec || tss->ts[2].tv_nsec) {
2210 		if (sk->sk_tsflags & SOF_TIMESTAMPING_RAW_HARDWARE)
2211 			has_timestamping = true;
2212 		else
2213 			tss->ts[2] = (struct timespec64) {0};
2214 	}
2215 
2216 	if (has_timestamping) {
2217 		tss->ts[1] = (struct timespec64) {0};
2218 		if (sock_flag(sk, SOCK_TSTAMP_NEW))
2219 			put_cmsg_scm_timestamping64(msg, tss);
2220 		else
2221 			put_cmsg_scm_timestamping(msg, tss);
2222 	}
2223 }
2224 
2225 static int tcp_inq_hint(struct sock *sk)
2226 {
2227 	const struct tcp_sock *tp = tcp_sk(sk);
2228 	u32 copied_seq = READ_ONCE(tp->copied_seq);
2229 	u32 rcv_nxt = READ_ONCE(tp->rcv_nxt);
2230 	int inq;
2231 
2232 	inq = rcv_nxt - copied_seq;
2233 	if (unlikely(inq < 0 || copied_seq != READ_ONCE(tp->copied_seq))) {
2234 		lock_sock(sk);
2235 		inq = tp->rcv_nxt - tp->copied_seq;
2236 		release_sock(sk);
2237 	}
2238 	/* After receiving a FIN, tell the user-space to continue reading
2239 	 * by returning a non-zero inq.
2240 	 */
2241 	if (inq == 0 && sock_flag(sk, SOCK_DONE))
2242 		inq = 1;
2243 	return inq;
2244 }
2245 
2246 /*
2247  *	This routine copies from a sock struct into the user buffer.
2248  *
2249  *	Technical note: in 2.3 we work on _locked_ socket, so that
2250  *	tricks with *seq access order and skb->users are not required.
2251  *	Probably, code can be easily improved even more.
2252  */
2253 
2254 static int tcp_recvmsg_locked(struct sock *sk, struct msghdr *msg, size_t len,
2255 			      int nonblock, int flags,
2256 			      struct scm_timestamping_internal *tss,
2257 			      int *cmsg_flags)
2258 {
2259 	struct tcp_sock *tp = tcp_sk(sk);
2260 	int copied = 0;
2261 	u32 peek_seq;
2262 	u32 *seq;
2263 	unsigned long used;
2264 	int err;
2265 	int target;		/* Read at least this many bytes */
2266 	long timeo;
2267 	struct sk_buff *skb, *last;
2268 	u32 urg_hole = 0;
2269 
2270 	err = -ENOTCONN;
2271 	if (sk->sk_state == TCP_LISTEN)
2272 		goto out;
2273 
2274 	if (tp->recvmsg_inq)
2275 		*cmsg_flags = 1;
2276 	timeo = sock_rcvtimeo(sk, nonblock);
2277 
2278 	/* Urgent data needs to be handled specially. */
2279 	if (flags & MSG_OOB)
2280 		goto recv_urg;
2281 
2282 	if (unlikely(tp->repair)) {
2283 		err = -EPERM;
2284 		if (!(flags & MSG_PEEK))
2285 			goto out;
2286 
2287 		if (tp->repair_queue == TCP_SEND_QUEUE)
2288 			goto recv_sndq;
2289 
2290 		err = -EINVAL;
2291 		if (tp->repair_queue == TCP_NO_QUEUE)
2292 			goto out;
2293 
2294 		/* 'common' recv queue MSG_PEEK-ing */
2295 	}
2296 
2297 	seq = &tp->copied_seq;
2298 	if (flags & MSG_PEEK) {
2299 		peek_seq = tp->copied_seq;
2300 		seq = &peek_seq;
2301 	}
2302 
2303 	target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
2304 
2305 	do {
2306 		u32 offset;
2307 
2308 		/* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
2309 		if (tp->urg_data && tp->urg_seq == *seq) {
2310 			if (copied)
2311 				break;
2312 			if (signal_pending(current)) {
2313 				copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
2314 				break;
2315 			}
2316 		}
2317 
2318 		/* Next get a buffer. */
2319 
2320 		last = skb_peek_tail(&sk->sk_receive_queue);
2321 		skb_queue_walk(&sk->sk_receive_queue, skb) {
2322 			last = skb;
2323 			/* Now that we have two receive queues this
2324 			 * shouldn't happen.
2325 			 */
2326 			if (WARN(before(*seq, TCP_SKB_CB(skb)->seq),
2327 				 "TCP recvmsg seq # bug: copied %X, seq %X, rcvnxt %X, fl %X\n",
2328 				 *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt,
2329 				 flags))
2330 				break;
2331 
2332 			offset = *seq - TCP_SKB_CB(skb)->seq;
2333 			if (unlikely(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
2334 				pr_err_once("%s: found a SYN, please report !\n", __func__);
2335 				offset--;
2336 			}
2337 			if (offset < skb->len)
2338 				goto found_ok_skb;
2339 			if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
2340 				goto found_fin_ok;
2341 			WARN(!(flags & MSG_PEEK),
2342 			     "TCP recvmsg seq # bug 2: copied %X, seq %X, rcvnxt %X, fl %X\n",
2343 			     *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt, flags);
2344 		}
2345 
2346 		/* Well, if we have backlog, try to process it now yet. */
2347 
2348 		if (copied >= target && !READ_ONCE(sk->sk_backlog.tail))
2349 			break;
2350 
2351 		if (copied) {
2352 			if (sk->sk_err ||
2353 			    sk->sk_state == TCP_CLOSE ||
2354 			    (sk->sk_shutdown & RCV_SHUTDOWN) ||
2355 			    !timeo ||
2356 			    signal_pending(current))
2357 				break;
2358 		} else {
2359 			if (sock_flag(sk, SOCK_DONE))
2360 				break;
2361 
2362 			if (sk->sk_err) {
2363 				copied = sock_error(sk);
2364 				break;
2365 			}
2366 
2367 			if (sk->sk_shutdown & RCV_SHUTDOWN)
2368 				break;
2369 
2370 			if (sk->sk_state == TCP_CLOSE) {
2371 				/* This occurs when user tries to read
2372 				 * from never connected socket.
2373 				 */
2374 				copied = -ENOTCONN;
2375 				break;
2376 			}
2377 
2378 			if (!timeo) {
2379 				copied = -EAGAIN;
2380 				break;
2381 			}
2382 
2383 			if (signal_pending(current)) {
2384 				copied = sock_intr_errno(timeo);
2385 				break;
2386 			}
2387 		}
2388 
2389 		tcp_cleanup_rbuf(sk, copied);
2390 
2391 		if (copied >= target) {
2392 			/* Do not sleep, just process backlog. */
2393 			release_sock(sk);
2394 			lock_sock(sk);
2395 		} else {
2396 			sk_wait_data(sk, &timeo, last);
2397 		}
2398 
2399 		if ((flags & MSG_PEEK) &&
2400 		    (peek_seq - copied - urg_hole != tp->copied_seq)) {
2401 			net_dbg_ratelimited("TCP(%s:%d): Application bug, race in MSG_PEEK\n",
2402 					    current->comm,
2403 					    task_pid_nr(current));
2404 			peek_seq = tp->copied_seq;
2405 		}
2406 		continue;
2407 
2408 found_ok_skb:
2409 		/* Ok so how much can we use? */
2410 		used = skb->len - offset;
2411 		if (len < used)
2412 			used = len;
2413 
2414 		/* Do we have urgent data here? */
2415 		if (tp->urg_data) {
2416 			u32 urg_offset = tp->urg_seq - *seq;
2417 			if (urg_offset < used) {
2418 				if (!urg_offset) {
2419 					if (!sock_flag(sk, SOCK_URGINLINE)) {
2420 						WRITE_ONCE(*seq, *seq + 1);
2421 						urg_hole++;
2422 						offset++;
2423 						used--;
2424 						if (!used)
2425 							goto skip_copy;
2426 					}
2427 				} else
2428 					used = urg_offset;
2429 			}
2430 		}
2431 
2432 		if (!(flags & MSG_TRUNC)) {
2433 			err = skb_copy_datagram_msg(skb, offset, msg, used);
2434 			if (err) {
2435 				/* Exception. Bailout! */
2436 				if (!copied)
2437 					copied = -EFAULT;
2438 				break;
2439 			}
2440 		}
2441 
2442 		WRITE_ONCE(*seq, *seq + used);
2443 		copied += used;
2444 		len -= used;
2445 
2446 		tcp_rcv_space_adjust(sk);
2447 
2448 skip_copy:
2449 		if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) {
2450 			tp->urg_data = 0;
2451 			tcp_fast_path_check(sk);
2452 		}
2453 
2454 		if (TCP_SKB_CB(skb)->has_rxtstamp) {
2455 			tcp_update_recv_tstamps(skb, tss);
2456 			*cmsg_flags |= 2;
2457 		}
2458 
2459 		if (used + offset < skb->len)
2460 			continue;
2461 
2462 		if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
2463 			goto found_fin_ok;
2464 		if (!(flags & MSG_PEEK))
2465 			sk_eat_skb(sk, skb);
2466 		continue;
2467 
2468 found_fin_ok:
2469 		/* Process the FIN. */
2470 		WRITE_ONCE(*seq, *seq + 1);
2471 		if (!(flags & MSG_PEEK))
2472 			sk_eat_skb(sk, skb);
2473 		break;
2474 	} while (len > 0);
2475 
2476 	/* According to UNIX98, msg_name/msg_namelen are ignored
2477 	 * on connected socket. I was just happy when found this 8) --ANK
2478 	 */
2479 
2480 	/* Clean up data we have read: This will do ACK frames. */
2481 	tcp_cleanup_rbuf(sk, copied);
2482 	return copied;
2483 
2484 out:
2485 	return err;
2486 
2487 recv_urg:
2488 	err = tcp_recv_urg(sk, msg, len, flags);
2489 	goto out;
2490 
2491 recv_sndq:
2492 	err = tcp_peek_sndq(sk, msg, len);
2493 	goto out;
2494 }
2495 
2496 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
2497 		int flags, int *addr_len)
2498 {
2499 	int cmsg_flags = 0, ret, inq;
2500 	struct scm_timestamping_internal tss;
2501 
2502 	if (unlikely(flags & MSG_ERRQUEUE))
2503 		return inet_recv_error(sk, msg, len, addr_len);
2504 
2505 	if (sk_can_busy_loop(sk) &&
2506 	    skb_queue_empty_lockless(&sk->sk_receive_queue) &&
2507 	    sk->sk_state == TCP_ESTABLISHED)
2508 		sk_busy_loop(sk, nonblock);
2509 
2510 	lock_sock(sk);
2511 	ret = tcp_recvmsg_locked(sk, msg, len, nonblock, flags, &tss,
2512 				 &cmsg_flags);
2513 	release_sock(sk);
2514 
2515 	if (cmsg_flags && ret >= 0) {
2516 		if (cmsg_flags & 2)
2517 			tcp_recv_timestamp(msg, sk, &tss);
2518 		if (cmsg_flags & 1) {
2519 			inq = tcp_inq_hint(sk);
2520 			put_cmsg(msg, SOL_TCP, TCP_CM_INQ, sizeof(inq), &inq);
2521 		}
2522 	}
2523 	return ret;
2524 }
2525 EXPORT_SYMBOL(tcp_recvmsg);
2526 
2527 void tcp_set_state(struct sock *sk, int state)
2528 {
2529 	int oldstate = sk->sk_state;
2530 
2531 	/* We defined a new enum for TCP states that are exported in BPF
2532 	 * so as not force the internal TCP states to be frozen. The
2533 	 * following checks will detect if an internal state value ever
2534 	 * differs from the BPF value. If this ever happens, then we will
2535 	 * need to remap the internal value to the BPF value before calling
2536 	 * tcp_call_bpf_2arg.
2537 	 */
2538 	BUILD_BUG_ON((int)BPF_TCP_ESTABLISHED != (int)TCP_ESTABLISHED);
2539 	BUILD_BUG_ON((int)BPF_TCP_SYN_SENT != (int)TCP_SYN_SENT);
2540 	BUILD_BUG_ON((int)BPF_TCP_SYN_RECV != (int)TCP_SYN_RECV);
2541 	BUILD_BUG_ON((int)BPF_TCP_FIN_WAIT1 != (int)TCP_FIN_WAIT1);
2542 	BUILD_BUG_ON((int)BPF_TCP_FIN_WAIT2 != (int)TCP_FIN_WAIT2);
2543 	BUILD_BUG_ON((int)BPF_TCP_TIME_WAIT != (int)TCP_TIME_WAIT);
2544 	BUILD_BUG_ON((int)BPF_TCP_CLOSE != (int)TCP_CLOSE);
2545 	BUILD_BUG_ON((int)BPF_TCP_CLOSE_WAIT != (int)TCP_CLOSE_WAIT);
2546 	BUILD_BUG_ON((int)BPF_TCP_LAST_ACK != (int)TCP_LAST_ACK);
2547 	BUILD_BUG_ON((int)BPF_TCP_LISTEN != (int)TCP_LISTEN);
2548 	BUILD_BUG_ON((int)BPF_TCP_CLOSING != (int)TCP_CLOSING);
2549 	BUILD_BUG_ON((int)BPF_TCP_NEW_SYN_RECV != (int)TCP_NEW_SYN_RECV);
2550 	BUILD_BUG_ON((int)BPF_TCP_MAX_STATES != (int)TCP_MAX_STATES);
2551 
2552 	if (BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), BPF_SOCK_OPS_STATE_CB_FLAG))
2553 		tcp_call_bpf_2arg(sk, BPF_SOCK_OPS_STATE_CB, oldstate, state);
2554 
2555 	switch (state) {
2556 	case TCP_ESTABLISHED:
2557 		if (oldstate != TCP_ESTABLISHED)
2558 			TCP_INC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
2559 		break;
2560 
2561 	case TCP_CLOSE:
2562 		if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED)
2563 			TCP_INC_STATS(sock_net(sk), TCP_MIB_ESTABRESETS);
2564 
2565 		sk->sk_prot->unhash(sk);
2566 		if (inet_csk(sk)->icsk_bind_hash &&
2567 		    !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
2568 			inet_put_port(sk);
2569 		fallthrough;
2570 	default:
2571 		if (oldstate == TCP_ESTABLISHED)
2572 			TCP_DEC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
2573 	}
2574 
2575 	/* Change state AFTER socket is unhashed to avoid closed
2576 	 * socket sitting in hash tables.
2577 	 */
2578 	inet_sk_state_store(sk, state);
2579 }
2580 EXPORT_SYMBOL_GPL(tcp_set_state);
2581 
2582 /*
2583  *	State processing on a close. This implements the state shift for
2584  *	sending our FIN frame. Note that we only send a FIN for some
2585  *	states. A shutdown() may have already sent the FIN, or we may be
2586  *	closed.
2587  */
2588 
2589 static const unsigned char new_state[16] = {
2590   /* current state:        new state:      action:	*/
2591   [0 /* (Invalid) */]	= TCP_CLOSE,
2592   [TCP_ESTABLISHED]	= TCP_FIN_WAIT1 | TCP_ACTION_FIN,
2593   [TCP_SYN_SENT]	= TCP_CLOSE,
2594   [TCP_SYN_RECV]	= TCP_FIN_WAIT1 | TCP_ACTION_FIN,
2595   [TCP_FIN_WAIT1]	= TCP_FIN_WAIT1,
2596   [TCP_FIN_WAIT2]	= TCP_FIN_WAIT2,
2597   [TCP_TIME_WAIT]	= TCP_CLOSE,
2598   [TCP_CLOSE]		= TCP_CLOSE,
2599   [TCP_CLOSE_WAIT]	= TCP_LAST_ACK  | TCP_ACTION_FIN,
2600   [TCP_LAST_ACK]	= TCP_LAST_ACK,
2601   [TCP_LISTEN]		= TCP_CLOSE,
2602   [TCP_CLOSING]		= TCP_CLOSING,
2603   [TCP_NEW_SYN_RECV]	= TCP_CLOSE,	/* should not happen ! */
2604 };
2605 
2606 static int tcp_close_state(struct sock *sk)
2607 {
2608 	int next = (int)new_state[sk->sk_state];
2609 	int ns = next & TCP_STATE_MASK;
2610 
2611 	tcp_set_state(sk, ns);
2612 
2613 	return next & TCP_ACTION_FIN;
2614 }
2615 
2616 /*
2617  *	Shutdown the sending side of a connection. Much like close except
2618  *	that we don't receive shut down or sock_set_flag(sk, SOCK_DEAD).
2619  */
2620 
2621 void tcp_shutdown(struct sock *sk, int how)
2622 {
2623 	/*	We need to grab some memory, and put together a FIN,
2624 	 *	and then put it into the queue to be sent.
2625 	 *		Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
2626 	 */
2627 	if (!(how & SEND_SHUTDOWN))
2628 		return;
2629 
2630 	/* If we've already sent a FIN, or it's a closed state, skip this. */
2631 	if ((1 << sk->sk_state) &
2632 	    (TCPF_ESTABLISHED | TCPF_SYN_SENT |
2633 	     TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
2634 		/* Clear out any half completed packets.  FIN if needed. */
2635 		if (tcp_close_state(sk))
2636 			tcp_send_fin(sk);
2637 	}
2638 }
2639 EXPORT_SYMBOL(tcp_shutdown);
2640 
2641 bool tcp_check_oom(struct sock *sk, int shift)
2642 {
2643 	bool too_many_orphans, out_of_socket_memory;
2644 
2645 	too_many_orphans = tcp_too_many_orphans(sk, shift);
2646 	out_of_socket_memory = tcp_out_of_memory(sk);
2647 
2648 	if (too_many_orphans)
2649 		net_info_ratelimited("too many orphaned sockets\n");
2650 	if (out_of_socket_memory)
2651 		net_info_ratelimited("out of memory -- consider tuning tcp_mem\n");
2652 	return too_many_orphans || out_of_socket_memory;
2653 }
2654 
2655 void __tcp_close(struct sock *sk, long timeout)
2656 {
2657 	struct sk_buff *skb;
2658 	int data_was_unread = 0;
2659 	int state;
2660 
2661 	sk->sk_shutdown = SHUTDOWN_MASK;
2662 
2663 	if (sk->sk_state == TCP_LISTEN) {
2664 		tcp_set_state(sk, TCP_CLOSE);
2665 
2666 		/* Special case. */
2667 		inet_csk_listen_stop(sk);
2668 
2669 		goto adjudge_to_death;
2670 	}
2671 
2672 	/*  We need to flush the recv. buffs.  We do this only on the
2673 	 *  descriptor close, not protocol-sourced closes, because the
2674 	 *  reader process may not have drained the data yet!
2675 	 */
2676 	while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
2677 		u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq;
2678 
2679 		if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
2680 			len--;
2681 		data_was_unread += len;
2682 		__kfree_skb(skb);
2683 	}
2684 
2685 	sk_mem_reclaim(sk);
2686 
2687 	/* If socket has been already reset (e.g. in tcp_reset()) - kill it. */
2688 	if (sk->sk_state == TCP_CLOSE)
2689 		goto adjudge_to_death;
2690 
2691 	/* As outlined in RFC 2525, section 2.17, we send a RST here because
2692 	 * data was lost. To witness the awful effects of the old behavior of
2693 	 * always doing a FIN, run an older 2.1.x kernel or 2.0.x, start a bulk
2694 	 * GET in an FTP client, suspend the process, wait for the client to
2695 	 * advertise a zero window, then kill -9 the FTP client, wheee...
2696 	 * Note: timeout is always zero in such a case.
2697 	 */
2698 	if (unlikely(tcp_sk(sk)->repair)) {
2699 		sk->sk_prot->disconnect(sk, 0);
2700 	} else if (data_was_unread) {
2701 		/* Unread data was tossed, zap the connection. */
2702 		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONCLOSE);
2703 		tcp_set_state(sk, TCP_CLOSE);
2704 		tcp_send_active_reset(sk, sk->sk_allocation);
2705 	} else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
2706 		/* Check zero linger _after_ checking for unread data. */
2707 		sk->sk_prot->disconnect(sk, 0);
2708 		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
2709 	} else if (tcp_close_state(sk)) {
2710 		/* We FIN if the application ate all the data before
2711 		 * zapping the connection.
2712 		 */
2713 
2714 		/* RED-PEN. Formally speaking, we have broken TCP state
2715 		 * machine. State transitions:
2716 		 *
2717 		 * TCP_ESTABLISHED -> TCP_FIN_WAIT1
2718 		 * TCP_SYN_RECV	-> TCP_FIN_WAIT1 (forget it, it's impossible)
2719 		 * TCP_CLOSE_WAIT -> TCP_LAST_ACK
2720 		 *
2721 		 * are legal only when FIN has been sent (i.e. in window),
2722 		 * rather than queued out of window. Purists blame.
2723 		 *
2724 		 * F.e. "RFC state" is ESTABLISHED,
2725 		 * if Linux state is FIN-WAIT-1, but FIN is still not sent.
2726 		 *
2727 		 * The visible declinations are that sometimes
2728 		 * we enter time-wait state, when it is not required really
2729 		 * (harmless), do not send active resets, when they are
2730 		 * required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when
2731 		 * they look as CLOSING or LAST_ACK for Linux)
2732 		 * Probably, I missed some more holelets.
2733 		 * 						--ANK
2734 		 * XXX (TFO) - To start off we don't support SYN+ACK+FIN
2735 		 * in a single packet! (May consider it later but will
2736 		 * probably need API support or TCP_CORK SYN-ACK until
2737 		 * data is written and socket is closed.)
2738 		 */
2739 		tcp_send_fin(sk);
2740 	}
2741 
2742 	sk_stream_wait_close(sk, timeout);
2743 
2744 adjudge_to_death:
2745 	state = sk->sk_state;
2746 	sock_hold(sk);
2747 	sock_orphan(sk);
2748 
2749 	local_bh_disable();
2750 	bh_lock_sock(sk);
2751 	/* remove backlog if any, without releasing ownership. */
2752 	__release_sock(sk);
2753 
2754 	percpu_counter_inc(sk->sk_prot->orphan_count);
2755 
2756 	/* Have we already been destroyed by a softirq or backlog? */
2757 	if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE)
2758 		goto out;
2759 
2760 	/*	This is a (useful) BSD violating of the RFC. There is a
2761 	 *	problem with TCP as specified in that the other end could
2762 	 *	keep a socket open forever with no application left this end.
2763 	 *	We use a 1 minute timeout (about the same as BSD) then kill
2764 	 *	our end. If they send after that then tough - BUT: long enough
2765 	 *	that we won't make the old 4*rto = almost no time - whoops
2766 	 *	reset mistake.
2767 	 *
2768 	 *	Nope, it was not mistake. It is really desired behaviour
2769 	 *	f.e. on http servers, when such sockets are useless, but
2770 	 *	consume significant resources. Let's do it with special
2771 	 *	linger2	option.					--ANK
2772 	 */
2773 
2774 	if (sk->sk_state == TCP_FIN_WAIT2) {
2775 		struct tcp_sock *tp = tcp_sk(sk);
2776 		if (tp->linger2 < 0) {
2777 			tcp_set_state(sk, TCP_CLOSE);
2778 			tcp_send_active_reset(sk, GFP_ATOMIC);
2779 			__NET_INC_STATS(sock_net(sk),
2780 					LINUX_MIB_TCPABORTONLINGER);
2781 		} else {
2782 			const int tmo = tcp_fin_time(sk);
2783 
2784 			if (tmo > TCP_TIMEWAIT_LEN) {
2785 				inet_csk_reset_keepalive_timer(sk,
2786 						tmo - TCP_TIMEWAIT_LEN);
2787 			} else {
2788 				tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
2789 				goto out;
2790 			}
2791 		}
2792 	}
2793 	if (sk->sk_state != TCP_CLOSE) {
2794 		sk_mem_reclaim(sk);
2795 		if (tcp_check_oom(sk, 0)) {
2796 			tcp_set_state(sk, TCP_CLOSE);
2797 			tcp_send_active_reset(sk, GFP_ATOMIC);
2798 			__NET_INC_STATS(sock_net(sk),
2799 					LINUX_MIB_TCPABORTONMEMORY);
2800 		} else if (!check_net(sock_net(sk))) {
2801 			/* Not possible to send reset; just close */
2802 			tcp_set_state(sk, TCP_CLOSE);
2803 		}
2804 	}
2805 
2806 	if (sk->sk_state == TCP_CLOSE) {
2807 		struct request_sock *req;
2808 
2809 		req = rcu_dereference_protected(tcp_sk(sk)->fastopen_rsk,
2810 						lockdep_sock_is_held(sk));
2811 		/* We could get here with a non-NULL req if the socket is
2812 		 * aborted (e.g., closed with unread data) before 3WHS
2813 		 * finishes.
2814 		 */
2815 		if (req)
2816 			reqsk_fastopen_remove(sk, req, false);
2817 		inet_csk_destroy_sock(sk);
2818 	}
2819 	/* Otherwise, socket is reprieved until protocol close. */
2820 
2821 out:
2822 	bh_unlock_sock(sk);
2823 	local_bh_enable();
2824 }
2825 
2826 void tcp_close(struct sock *sk, long timeout)
2827 {
2828 	lock_sock(sk);
2829 	__tcp_close(sk, timeout);
2830 	release_sock(sk);
2831 	sock_put(sk);
2832 }
2833 EXPORT_SYMBOL(tcp_close);
2834 
2835 /* These states need RST on ABORT according to RFC793 */
2836 
2837 static inline bool tcp_need_reset(int state)
2838 {
2839 	return (1 << state) &
2840 	       (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
2841 		TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
2842 }
2843 
2844 static void tcp_rtx_queue_purge(struct sock *sk)
2845 {
2846 	struct rb_node *p = rb_first(&sk->tcp_rtx_queue);
2847 
2848 	tcp_sk(sk)->highest_sack = NULL;
2849 	while (p) {
2850 		struct sk_buff *skb = rb_to_skb(p);
2851 
2852 		p = rb_next(p);
2853 		/* Since we are deleting whole queue, no need to
2854 		 * list_del(&skb->tcp_tsorted_anchor)
2855 		 */
2856 		tcp_rtx_queue_unlink(skb, sk);
2857 		sk_wmem_free_skb(sk, skb);
2858 	}
2859 }
2860 
2861 void tcp_write_queue_purge(struct sock *sk)
2862 {
2863 	struct sk_buff *skb;
2864 
2865 	tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
2866 	while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) {
2867 		tcp_skb_tsorted_anchor_cleanup(skb);
2868 		sk_wmem_free_skb(sk, skb);
2869 	}
2870 	tcp_rtx_queue_purge(sk);
2871 	skb = sk->sk_tx_skb_cache;
2872 	if (skb) {
2873 		__kfree_skb(skb);
2874 		sk->sk_tx_skb_cache = NULL;
2875 	}
2876 	INIT_LIST_HEAD(&tcp_sk(sk)->tsorted_sent_queue);
2877 	sk_mem_reclaim(sk);
2878 	tcp_clear_all_retrans_hints(tcp_sk(sk));
2879 	tcp_sk(sk)->packets_out = 0;
2880 	inet_csk(sk)->icsk_backoff = 0;
2881 }
2882 
2883 int tcp_disconnect(struct sock *sk, int flags)
2884 {
2885 	struct inet_sock *inet = inet_sk(sk);
2886 	struct inet_connection_sock *icsk = inet_csk(sk);
2887 	struct tcp_sock *tp = tcp_sk(sk);
2888 	int old_state = sk->sk_state;
2889 	u32 seq;
2890 
2891 	if (old_state != TCP_CLOSE)
2892 		tcp_set_state(sk, TCP_CLOSE);
2893 
2894 	/* ABORT function of RFC793 */
2895 	if (old_state == TCP_LISTEN) {
2896 		inet_csk_listen_stop(sk);
2897 	} else if (unlikely(tp->repair)) {
2898 		sk->sk_err = ECONNABORTED;
2899 	} else if (tcp_need_reset(old_state) ||
2900 		   (tp->snd_nxt != tp->write_seq &&
2901 		    (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
2902 		/* The last check adjusts for discrepancy of Linux wrt. RFC
2903 		 * states
2904 		 */
2905 		tcp_send_active_reset(sk, gfp_any());
2906 		sk->sk_err = ECONNRESET;
2907 	} else if (old_state == TCP_SYN_SENT)
2908 		sk->sk_err = ECONNRESET;
2909 
2910 	tcp_clear_xmit_timers(sk);
2911 	__skb_queue_purge(&sk->sk_receive_queue);
2912 	if (sk->sk_rx_skb_cache) {
2913 		__kfree_skb(sk->sk_rx_skb_cache);
2914 		sk->sk_rx_skb_cache = NULL;
2915 	}
2916 	WRITE_ONCE(tp->copied_seq, tp->rcv_nxt);
2917 	tp->urg_data = 0;
2918 	tcp_write_queue_purge(sk);
2919 	tcp_fastopen_active_disable_ofo_check(sk);
2920 	skb_rbtree_purge(&tp->out_of_order_queue);
2921 
2922 	inet->inet_dport = 0;
2923 
2924 	if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
2925 		inet_reset_saddr(sk);
2926 
2927 	sk->sk_shutdown = 0;
2928 	sock_reset_flag(sk, SOCK_DONE);
2929 	tp->srtt_us = 0;
2930 	tp->mdev_us = jiffies_to_usecs(TCP_TIMEOUT_INIT);
2931 	tp->rcv_rtt_last_tsecr = 0;
2932 
2933 	seq = tp->write_seq + tp->max_window + 2;
2934 	if (!seq)
2935 		seq = 1;
2936 	WRITE_ONCE(tp->write_seq, seq);
2937 
2938 	icsk->icsk_backoff = 0;
2939 	icsk->icsk_probes_out = 0;
2940 	icsk->icsk_probes_tstamp = 0;
2941 	icsk->icsk_rto = TCP_TIMEOUT_INIT;
2942 	icsk->icsk_rto_min = TCP_RTO_MIN;
2943 	icsk->icsk_delack_max = TCP_DELACK_MAX;
2944 	tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
2945 	tp->snd_cwnd = TCP_INIT_CWND;
2946 	tp->snd_cwnd_cnt = 0;
2947 	tp->window_clamp = 0;
2948 	tp->delivered = 0;
2949 	tp->delivered_ce = 0;
2950 	if (icsk->icsk_ca_ops->release)
2951 		icsk->icsk_ca_ops->release(sk);
2952 	memset(icsk->icsk_ca_priv, 0, sizeof(icsk->icsk_ca_priv));
2953 	icsk->icsk_ca_initialized = 0;
2954 	tcp_set_ca_state(sk, TCP_CA_Open);
2955 	tp->is_sack_reneg = 0;
2956 	tcp_clear_retrans(tp);
2957 	tp->total_retrans = 0;
2958 	inet_csk_delack_init(sk);
2959 	/* Initialize rcv_mss to TCP_MIN_MSS to avoid division by 0
2960 	 * issue in __tcp_select_window()
2961 	 */
2962 	icsk->icsk_ack.rcv_mss = TCP_MIN_MSS;
2963 	memset(&tp->rx_opt, 0, sizeof(tp->rx_opt));
2964 	__sk_dst_reset(sk);
2965 	dst_release(sk->sk_rx_dst);
2966 	sk->sk_rx_dst = NULL;
2967 	tcp_saved_syn_free(tp);
2968 	tp->compressed_ack = 0;
2969 	tp->segs_in = 0;
2970 	tp->segs_out = 0;
2971 	tp->bytes_sent = 0;
2972 	tp->bytes_acked = 0;
2973 	tp->bytes_received = 0;
2974 	tp->bytes_retrans = 0;
2975 	tp->data_segs_in = 0;
2976 	tp->data_segs_out = 0;
2977 	tp->duplicate_sack[0].start_seq = 0;
2978 	tp->duplicate_sack[0].end_seq = 0;
2979 	tp->dsack_dups = 0;
2980 	tp->reord_seen = 0;
2981 	tp->retrans_out = 0;
2982 	tp->sacked_out = 0;
2983 	tp->tlp_high_seq = 0;
2984 	tp->last_oow_ack_time = 0;
2985 	/* There's a bubble in the pipe until at least the first ACK. */
2986 	tp->app_limited = ~0U;
2987 	tp->rack.mstamp = 0;
2988 	tp->rack.advanced = 0;
2989 	tp->rack.reo_wnd_steps = 1;
2990 	tp->rack.last_delivered = 0;
2991 	tp->rack.reo_wnd_persist = 0;
2992 	tp->rack.dsack_seen = 0;
2993 	tp->syn_data_acked = 0;
2994 	tp->rx_opt.saw_tstamp = 0;
2995 	tp->rx_opt.dsack = 0;
2996 	tp->rx_opt.num_sacks = 0;
2997 	tp->rcv_ooopack = 0;
2998 
2999 
3000 	/* Clean up fastopen related fields */
3001 	tcp_free_fastopen_req(tp);
3002 	inet->defer_connect = 0;
3003 	tp->fastopen_client_fail = 0;
3004 
3005 	WARN_ON(inet->inet_num && !icsk->icsk_bind_hash);
3006 
3007 	if (sk->sk_frag.page) {
3008 		put_page(sk->sk_frag.page);
3009 		sk->sk_frag.page = NULL;
3010 		sk->sk_frag.offset = 0;
3011 	}
3012 
3013 	sk->sk_error_report(sk);
3014 	return 0;
3015 }
3016 EXPORT_SYMBOL(tcp_disconnect);
3017 
3018 static inline bool tcp_can_repair_sock(const struct sock *sk)
3019 {
3020 	return ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN) &&
3021 		(sk->sk_state != TCP_LISTEN);
3022 }
3023 
3024 static int tcp_repair_set_window(struct tcp_sock *tp, sockptr_t optbuf, int len)
3025 {
3026 	struct tcp_repair_window opt;
3027 
3028 	if (!tp->repair)
3029 		return -EPERM;
3030 
3031 	if (len != sizeof(opt))
3032 		return -EINVAL;
3033 
3034 	if (copy_from_sockptr(&opt, optbuf, sizeof(opt)))
3035 		return -EFAULT;
3036 
3037 	if (opt.max_window < opt.snd_wnd)
3038 		return -EINVAL;
3039 
3040 	if (after(opt.snd_wl1, tp->rcv_nxt + opt.rcv_wnd))
3041 		return -EINVAL;
3042 
3043 	if (after(opt.rcv_wup, tp->rcv_nxt))
3044 		return -EINVAL;
3045 
3046 	tp->snd_wl1	= opt.snd_wl1;
3047 	tp->snd_wnd	= opt.snd_wnd;
3048 	tp->max_window	= opt.max_window;
3049 
3050 	tp->rcv_wnd	= opt.rcv_wnd;
3051 	tp->rcv_wup	= opt.rcv_wup;
3052 
3053 	return 0;
3054 }
3055 
3056 static int tcp_repair_options_est(struct sock *sk, sockptr_t optbuf,
3057 		unsigned int len)
3058 {
3059 	struct tcp_sock *tp = tcp_sk(sk);
3060 	struct tcp_repair_opt opt;
3061 	size_t offset = 0;
3062 
3063 	while (len >= sizeof(opt)) {
3064 		if (copy_from_sockptr_offset(&opt, optbuf, offset, sizeof(opt)))
3065 			return -EFAULT;
3066 
3067 		offset += sizeof(opt);
3068 		len -= sizeof(opt);
3069 
3070 		switch (opt.opt_code) {
3071 		case TCPOPT_MSS:
3072 			tp->rx_opt.mss_clamp = opt.opt_val;
3073 			tcp_mtup_init(sk);
3074 			break;
3075 		case TCPOPT_WINDOW:
3076 			{
3077 				u16 snd_wscale = opt.opt_val & 0xFFFF;
3078 				u16 rcv_wscale = opt.opt_val >> 16;
3079 
3080 				if (snd_wscale > TCP_MAX_WSCALE || rcv_wscale > TCP_MAX_WSCALE)
3081 					return -EFBIG;
3082 
3083 				tp->rx_opt.snd_wscale = snd_wscale;
3084 				tp->rx_opt.rcv_wscale = rcv_wscale;
3085 				tp->rx_opt.wscale_ok = 1;
3086 			}
3087 			break;
3088 		case TCPOPT_SACK_PERM:
3089 			if (opt.opt_val != 0)
3090 				return -EINVAL;
3091 
3092 			tp->rx_opt.sack_ok |= TCP_SACK_SEEN;
3093 			break;
3094 		case TCPOPT_TIMESTAMP:
3095 			if (opt.opt_val != 0)
3096 				return -EINVAL;
3097 
3098 			tp->rx_opt.tstamp_ok = 1;
3099 			break;
3100 		}
3101 	}
3102 
3103 	return 0;
3104 }
3105 
3106 DEFINE_STATIC_KEY_FALSE(tcp_tx_delay_enabled);
3107 EXPORT_SYMBOL(tcp_tx_delay_enabled);
3108 
3109 static void tcp_enable_tx_delay(void)
3110 {
3111 	if (!static_branch_unlikely(&tcp_tx_delay_enabled)) {
3112 		static int __tcp_tx_delay_enabled = 0;
3113 
3114 		if (cmpxchg(&__tcp_tx_delay_enabled, 0, 1) == 0) {
3115 			static_branch_enable(&tcp_tx_delay_enabled);
3116 			pr_info("TCP_TX_DELAY enabled\n");
3117 		}
3118 	}
3119 }
3120 
3121 /* When set indicates to always queue non-full frames.  Later the user clears
3122  * this option and we transmit any pending partial frames in the queue.  This is
3123  * meant to be used alongside sendfile() to get properly filled frames when the
3124  * user (for example) must write out headers with a write() call first and then
3125  * use sendfile to send out the data parts.
3126  *
3127  * TCP_CORK can be set together with TCP_NODELAY and it is stronger than
3128  * TCP_NODELAY.
3129  */
3130 static void __tcp_sock_set_cork(struct sock *sk, bool on)
3131 {
3132 	struct tcp_sock *tp = tcp_sk(sk);
3133 
3134 	if (on) {
3135 		tp->nonagle |= TCP_NAGLE_CORK;
3136 	} else {
3137 		tp->nonagle &= ~TCP_NAGLE_CORK;
3138 		if (tp->nonagle & TCP_NAGLE_OFF)
3139 			tp->nonagle |= TCP_NAGLE_PUSH;
3140 		tcp_push_pending_frames(sk);
3141 	}
3142 }
3143 
3144 void tcp_sock_set_cork(struct sock *sk, bool on)
3145 {
3146 	lock_sock(sk);
3147 	__tcp_sock_set_cork(sk, on);
3148 	release_sock(sk);
3149 }
3150 EXPORT_SYMBOL(tcp_sock_set_cork);
3151 
3152 /* TCP_NODELAY is weaker than TCP_CORK, so that this option on corked socket is
3153  * remembered, but it is not activated until cork is cleared.
3154  *
3155  * However, when TCP_NODELAY is set we make an explicit push, which overrides
3156  * even TCP_CORK for currently queued segments.
3157  */
3158 static void __tcp_sock_set_nodelay(struct sock *sk, bool on)
3159 {
3160 	if (on) {
3161 		tcp_sk(sk)->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH;
3162 		tcp_push_pending_frames(sk);
3163 	} else {
3164 		tcp_sk(sk)->nonagle &= ~TCP_NAGLE_OFF;
3165 	}
3166 }
3167 
3168 void tcp_sock_set_nodelay(struct sock *sk)
3169 {
3170 	lock_sock(sk);
3171 	__tcp_sock_set_nodelay(sk, true);
3172 	release_sock(sk);
3173 }
3174 EXPORT_SYMBOL(tcp_sock_set_nodelay);
3175 
3176 static void __tcp_sock_set_quickack(struct sock *sk, int val)
3177 {
3178 	if (!val) {
3179 		inet_csk_enter_pingpong_mode(sk);
3180 		return;
3181 	}
3182 
3183 	inet_csk_exit_pingpong_mode(sk);
3184 	if ((1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
3185 	    inet_csk_ack_scheduled(sk)) {
3186 		inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_PUSHED;
3187 		tcp_cleanup_rbuf(sk, 1);
3188 		if (!(val & 1))
3189 			inet_csk_enter_pingpong_mode(sk);
3190 	}
3191 }
3192 
3193 void tcp_sock_set_quickack(struct sock *sk, int val)
3194 {
3195 	lock_sock(sk);
3196 	__tcp_sock_set_quickack(sk, val);
3197 	release_sock(sk);
3198 }
3199 EXPORT_SYMBOL(tcp_sock_set_quickack);
3200 
3201 int tcp_sock_set_syncnt(struct sock *sk, int val)
3202 {
3203 	if (val < 1 || val > MAX_TCP_SYNCNT)
3204 		return -EINVAL;
3205 
3206 	lock_sock(sk);
3207 	inet_csk(sk)->icsk_syn_retries = val;
3208 	release_sock(sk);
3209 	return 0;
3210 }
3211 EXPORT_SYMBOL(tcp_sock_set_syncnt);
3212 
3213 void tcp_sock_set_user_timeout(struct sock *sk, u32 val)
3214 {
3215 	lock_sock(sk);
3216 	inet_csk(sk)->icsk_user_timeout = val;
3217 	release_sock(sk);
3218 }
3219 EXPORT_SYMBOL(tcp_sock_set_user_timeout);
3220 
3221 int tcp_sock_set_keepidle_locked(struct sock *sk, int val)
3222 {
3223 	struct tcp_sock *tp = tcp_sk(sk);
3224 
3225 	if (val < 1 || val > MAX_TCP_KEEPIDLE)
3226 		return -EINVAL;
3227 
3228 	tp->keepalive_time = val * HZ;
3229 	if (sock_flag(sk, SOCK_KEEPOPEN) &&
3230 	    !((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))) {
3231 		u32 elapsed = keepalive_time_elapsed(tp);
3232 
3233 		if (tp->keepalive_time > elapsed)
3234 			elapsed = tp->keepalive_time - elapsed;
3235 		else
3236 			elapsed = 0;
3237 		inet_csk_reset_keepalive_timer(sk, elapsed);
3238 	}
3239 
3240 	return 0;
3241 }
3242 
3243 int tcp_sock_set_keepidle(struct sock *sk, int val)
3244 {
3245 	int err;
3246 
3247 	lock_sock(sk);
3248 	err = tcp_sock_set_keepidle_locked(sk, val);
3249 	release_sock(sk);
3250 	return err;
3251 }
3252 EXPORT_SYMBOL(tcp_sock_set_keepidle);
3253 
3254 int tcp_sock_set_keepintvl(struct sock *sk, int val)
3255 {
3256 	if (val < 1 || val > MAX_TCP_KEEPINTVL)
3257 		return -EINVAL;
3258 
3259 	lock_sock(sk);
3260 	tcp_sk(sk)->keepalive_intvl = val * HZ;
3261 	release_sock(sk);
3262 	return 0;
3263 }
3264 EXPORT_SYMBOL(tcp_sock_set_keepintvl);
3265 
3266 int tcp_sock_set_keepcnt(struct sock *sk, int val)
3267 {
3268 	if (val < 1 || val > MAX_TCP_KEEPCNT)
3269 		return -EINVAL;
3270 
3271 	lock_sock(sk);
3272 	tcp_sk(sk)->keepalive_probes = val;
3273 	release_sock(sk);
3274 	return 0;
3275 }
3276 EXPORT_SYMBOL(tcp_sock_set_keepcnt);
3277 
3278 int tcp_set_window_clamp(struct sock *sk, int val)
3279 {
3280 	struct tcp_sock *tp = tcp_sk(sk);
3281 
3282 	if (!val) {
3283 		if (sk->sk_state != TCP_CLOSE)
3284 			return -EINVAL;
3285 		tp->window_clamp = 0;
3286 	} else {
3287 		tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
3288 			SOCK_MIN_RCVBUF / 2 : val;
3289 	}
3290 	return 0;
3291 }
3292 
3293 /*
3294  *	Socket option code for TCP.
3295  */
3296 static int do_tcp_setsockopt(struct sock *sk, int level, int optname,
3297 		sockptr_t optval, unsigned int optlen)
3298 {
3299 	struct tcp_sock *tp = tcp_sk(sk);
3300 	struct inet_connection_sock *icsk = inet_csk(sk);
3301 	struct net *net = sock_net(sk);
3302 	int val;
3303 	int err = 0;
3304 
3305 	/* These are data/string values, all the others are ints */
3306 	switch (optname) {
3307 	case TCP_CONGESTION: {
3308 		char name[TCP_CA_NAME_MAX];
3309 
3310 		if (optlen < 1)
3311 			return -EINVAL;
3312 
3313 		val = strncpy_from_sockptr(name, optval,
3314 					min_t(long, TCP_CA_NAME_MAX-1, optlen));
3315 		if (val < 0)
3316 			return -EFAULT;
3317 		name[val] = 0;
3318 
3319 		lock_sock(sk);
3320 		err = tcp_set_congestion_control(sk, name, true,
3321 						 ns_capable(sock_net(sk)->user_ns,
3322 							    CAP_NET_ADMIN));
3323 		release_sock(sk);
3324 		return err;
3325 	}
3326 	case TCP_ULP: {
3327 		char name[TCP_ULP_NAME_MAX];
3328 
3329 		if (optlen < 1)
3330 			return -EINVAL;
3331 
3332 		val = strncpy_from_sockptr(name, optval,
3333 					min_t(long, TCP_ULP_NAME_MAX - 1,
3334 					      optlen));
3335 		if (val < 0)
3336 			return -EFAULT;
3337 		name[val] = 0;
3338 
3339 		lock_sock(sk);
3340 		err = tcp_set_ulp(sk, name);
3341 		release_sock(sk);
3342 		return err;
3343 	}
3344 	case TCP_FASTOPEN_KEY: {
3345 		__u8 key[TCP_FASTOPEN_KEY_BUF_LENGTH];
3346 		__u8 *backup_key = NULL;
3347 
3348 		/* Allow a backup key as well to facilitate key rotation
3349 		 * First key is the active one.
3350 		 */
3351 		if (optlen != TCP_FASTOPEN_KEY_LENGTH &&
3352 		    optlen != TCP_FASTOPEN_KEY_BUF_LENGTH)
3353 			return -EINVAL;
3354 
3355 		if (copy_from_sockptr(key, optval, optlen))
3356 			return -EFAULT;
3357 
3358 		if (optlen == TCP_FASTOPEN_KEY_BUF_LENGTH)
3359 			backup_key = key + TCP_FASTOPEN_KEY_LENGTH;
3360 
3361 		return tcp_fastopen_reset_cipher(net, sk, key, backup_key);
3362 	}
3363 	default:
3364 		/* fallthru */
3365 		break;
3366 	}
3367 
3368 	if (optlen < sizeof(int))
3369 		return -EINVAL;
3370 
3371 	if (copy_from_sockptr(&val, optval, sizeof(val)))
3372 		return -EFAULT;
3373 
3374 	lock_sock(sk);
3375 
3376 	switch (optname) {
3377 	case TCP_MAXSEG:
3378 		/* Values greater than interface MTU won't take effect. However
3379 		 * at the point when this call is done we typically don't yet
3380 		 * know which interface is going to be used
3381 		 */
3382 		if (val && (val < TCP_MIN_MSS || val > MAX_TCP_WINDOW)) {
3383 			err = -EINVAL;
3384 			break;
3385 		}
3386 		tp->rx_opt.user_mss = val;
3387 		break;
3388 
3389 	case TCP_NODELAY:
3390 		__tcp_sock_set_nodelay(sk, val);
3391 		break;
3392 
3393 	case TCP_THIN_LINEAR_TIMEOUTS:
3394 		if (val < 0 || val > 1)
3395 			err = -EINVAL;
3396 		else
3397 			tp->thin_lto = val;
3398 		break;
3399 
3400 	case TCP_THIN_DUPACK:
3401 		if (val < 0 || val > 1)
3402 			err = -EINVAL;
3403 		break;
3404 
3405 	case TCP_REPAIR:
3406 		if (!tcp_can_repair_sock(sk))
3407 			err = -EPERM;
3408 		else if (val == TCP_REPAIR_ON) {
3409 			tp->repair = 1;
3410 			sk->sk_reuse = SK_FORCE_REUSE;
3411 			tp->repair_queue = TCP_NO_QUEUE;
3412 		} else if (val == TCP_REPAIR_OFF) {
3413 			tp->repair = 0;
3414 			sk->sk_reuse = SK_NO_REUSE;
3415 			tcp_send_window_probe(sk);
3416 		} else if (val == TCP_REPAIR_OFF_NO_WP) {
3417 			tp->repair = 0;
3418 			sk->sk_reuse = SK_NO_REUSE;
3419 		} else
3420 			err = -EINVAL;
3421 
3422 		break;
3423 
3424 	case TCP_REPAIR_QUEUE:
3425 		if (!tp->repair)
3426 			err = -EPERM;
3427 		else if ((unsigned int)val < TCP_QUEUES_NR)
3428 			tp->repair_queue = val;
3429 		else
3430 			err = -EINVAL;
3431 		break;
3432 
3433 	case TCP_QUEUE_SEQ:
3434 		if (sk->sk_state != TCP_CLOSE)
3435 			err = -EPERM;
3436 		else if (tp->repair_queue == TCP_SEND_QUEUE)
3437 			WRITE_ONCE(tp->write_seq, val);
3438 		else if (tp->repair_queue == TCP_RECV_QUEUE) {
3439 			WRITE_ONCE(tp->rcv_nxt, val);
3440 			WRITE_ONCE(tp->copied_seq, val);
3441 		}
3442 		else
3443 			err = -EINVAL;
3444 		break;
3445 
3446 	case TCP_REPAIR_OPTIONS:
3447 		if (!tp->repair)
3448 			err = -EINVAL;
3449 		else if (sk->sk_state == TCP_ESTABLISHED)
3450 			err = tcp_repair_options_est(sk, optval, optlen);
3451 		else
3452 			err = -EPERM;
3453 		break;
3454 
3455 	case TCP_CORK:
3456 		__tcp_sock_set_cork(sk, val);
3457 		break;
3458 
3459 	case TCP_KEEPIDLE:
3460 		err = tcp_sock_set_keepidle_locked(sk, val);
3461 		break;
3462 	case TCP_KEEPINTVL:
3463 		if (val < 1 || val > MAX_TCP_KEEPINTVL)
3464 			err = -EINVAL;
3465 		else
3466 			tp->keepalive_intvl = val * HZ;
3467 		break;
3468 	case TCP_KEEPCNT:
3469 		if (val < 1 || val > MAX_TCP_KEEPCNT)
3470 			err = -EINVAL;
3471 		else
3472 			tp->keepalive_probes = val;
3473 		break;
3474 	case TCP_SYNCNT:
3475 		if (val < 1 || val > MAX_TCP_SYNCNT)
3476 			err = -EINVAL;
3477 		else
3478 			icsk->icsk_syn_retries = val;
3479 		break;
3480 
3481 	case TCP_SAVE_SYN:
3482 		/* 0: disable, 1: enable, 2: start from ether_header */
3483 		if (val < 0 || val > 2)
3484 			err = -EINVAL;
3485 		else
3486 			tp->save_syn = val;
3487 		break;
3488 
3489 	case TCP_LINGER2:
3490 		if (val < 0)
3491 			tp->linger2 = -1;
3492 		else if (val > TCP_FIN_TIMEOUT_MAX / HZ)
3493 			tp->linger2 = TCP_FIN_TIMEOUT_MAX;
3494 		else
3495 			tp->linger2 = val * HZ;
3496 		break;
3497 
3498 	case TCP_DEFER_ACCEPT:
3499 		/* Translate value in seconds to number of retransmits */
3500 		icsk->icsk_accept_queue.rskq_defer_accept =
3501 			secs_to_retrans(val, TCP_TIMEOUT_INIT / HZ,
3502 					TCP_RTO_MAX / HZ);
3503 		break;
3504 
3505 	case TCP_WINDOW_CLAMP:
3506 		err = tcp_set_window_clamp(sk, val);
3507 		break;
3508 
3509 	case TCP_QUICKACK:
3510 		__tcp_sock_set_quickack(sk, val);
3511 		break;
3512 
3513 #ifdef CONFIG_TCP_MD5SIG
3514 	case TCP_MD5SIG:
3515 	case TCP_MD5SIG_EXT:
3516 		err = tp->af_specific->md5_parse(sk, optname, optval, optlen);
3517 		break;
3518 #endif
3519 	case TCP_USER_TIMEOUT:
3520 		/* Cap the max time in ms TCP will retry or probe the window
3521 		 * before giving up and aborting (ETIMEDOUT) a connection.
3522 		 */
3523 		if (val < 0)
3524 			err = -EINVAL;
3525 		else
3526 			icsk->icsk_user_timeout = val;
3527 		break;
3528 
3529 	case TCP_FASTOPEN:
3530 		if (val >= 0 && ((1 << sk->sk_state) & (TCPF_CLOSE |
3531 		    TCPF_LISTEN))) {
3532 			tcp_fastopen_init_key_once(net);
3533 
3534 			fastopen_queue_tune(sk, val);
3535 		} else {
3536 			err = -EINVAL;
3537 		}
3538 		break;
3539 	case TCP_FASTOPEN_CONNECT:
3540 		if (val > 1 || val < 0) {
3541 			err = -EINVAL;
3542 		} else if (net->ipv4.sysctl_tcp_fastopen & TFO_CLIENT_ENABLE) {
3543 			if (sk->sk_state == TCP_CLOSE)
3544 				tp->fastopen_connect = val;
3545 			else
3546 				err = -EINVAL;
3547 		} else {
3548 			err = -EOPNOTSUPP;
3549 		}
3550 		break;
3551 	case TCP_FASTOPEN_NO_COOKIE:
3552 		if (val > 1 || val < 0)
3553 			err = -EINVAL;
3554 		else if (!((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
3555 			err = -EINVAL;
3556 		else
3557 			tp->fastopen_no_cookie = val;
3558 		break;
3559 	case TCP_TIMESTAMP:
3560 		if (!tp->repair)
3561 			err = -EPERM;
3562 		else
3563 			tp->tsoffset = val - tcp_time_stamp_raw();
3564 		break;
3565 	case TCP_REPAIR_WINDOW:
3566 		err = tcp_repair_set_window(tp, optval, optlen);
3567 		break;
3568 	case TCP_NOTSENT_LOWAT:
3569 		tp->notsent_lowat = val;
3570 		sk->sk_write_space(sk);
3571 		break;
3572 	case TCP_INQ:
3573 		if (val > 1 || val < 0)
3574 			err = -EINVAL;
3575 		else
3576 			tp->recvmsg_inq = val;
3577 		break;
3578 	case TCP_TX_DELAY:
3579 		if (val)
3580 			tcp_enable_tx_delay();
3581 		tp->tcp_tx_delay = val;
3582 		break;
3583 	default:
3584 		err = -ENOPROTOOPT;
3585 		break;
3586 	}
3587 
3588 	release_sock(sk);
3589 	return err;
3590 }
3591 
3592 int tcp_setsockopt(struct sock *sk, int level, int optname, sockptr_t optval,
3593 		   unsigned int optlen)
3594 {
3595 	const struct inet_connection_sock *icsk = inet_csk(sk);
3596 
3597 	if (level != SOL_TCP)
3598 		return icsk->icsk_af_ops->setsockopt(sk, level, optname,
3599 						     optval, optlen);
3600 	return do_tcp_setsockopt(sk, level, optname, optval, optlen);
3601 }
3602 EXPORT_SYMBOL(tcp_setsockopt);
3603 
3604 static void tcp_get_info_chrono_stats(const struct tcp_sock *tp,
3605 				      struct tcp_info *info)
3606 {
3607 	u64 stats[__TCP_CHRONO_MAX], total = 0;
3608 	enum tcp_chrono i;
3609 
3610 	for (i = TCP_CHRONO_BUSY; i < __TCP_CHRONO_MAX; ++i) {
3611 		stats[i] = tp->chrono_stat[i - 1];
3612 		if (i == tp->chrono_type)
3613 			stats[i] += tcp_jiffies32 - tp->chrono_start;
3614 		stats[i] *= USEC_PER_SEC / HZ;
3615 		total += stats[i];
3616 	}
3617 
3618 	info->tcpi_busy_time = total;
3619 	info->tcpi_rwnd_limited = stats[TCP_CHRONO_RWND_LIMITED];
3620 	info->tcpi_sndbuf_limited = stats[TCP_CHRONO_SNDBUF_LIMITED];
3621 }
3622 
3623 /* Return information about state of tcp endpoint in API format. */
3624 void tcp_get_info(struct sock *sk, struct tcp_info *info)
3625 {
3626 	const struct tcp_sock *tp = tcp_sk(sk); /* iff sk_type == SOCK_STREAM */
3627 	const struct inet_connection_sock *icsk = inet_csk(sk);
3628 	unsigned long rate;
3629 	u32 now;
3630 	u64 rate64;
3631 	bool slow;
3632 
3633 	memset(info, 0, sizeof(*info));
3634 	if (sk->sk_type != SOCK_STREAM)
3635 		return;
3636 
3637 	info->tcpi_state = inet_sk_state_load(sk);
3638 
3639 	/* Report meaningful fields for all TCP states, including listeners */
3640 	rate = READ_ONCE(sk->sk_pacing_rate);
3641 	rate64 = (rate != ~0UL) ? rate : ~0ULL;
3642 	info->tcpi_pacing_rate = rate64;
3643 
3644 	rate = READ_ONCE(sk->sk_max_pacing_rate);
3645 	rate64 = (rate != ~0UL) ? rate : ~0ULL;
3646 	info->tcpi_max_pacing_rate = rate64;
3647 
3648 	info->tcpi_reordering = tp->reordering;
3649 	info->tcpi_snd_cwnd = tp->snd_cwnd;
3650 
3651 	if (info->tcpi_state == TCP_LISTEN) {
3652 		/* listeners aliased fields :
3653 		 * tcpi_unacked -> Number of children ready for accept()
3654 		 * tcpi_sacked  -> max backlog
3655 		 */
3656 		info->tcpi_unacked = READ_ONCE(sk->sk_ack_backlog);
3657 		info->tcpi_sacked = READ_ONCE(sk->sk_max_ack_backlog);
3658 		return;
3659 	}
3660 
3661 	slow = lock_sock_fast(sk);
3662 
3663 	info->tcpi_ca_state = icsk->icsk_ca_state;
3664 	info->tcpi_retransmits = icsk->icsk_retransmits;
3665 	info->tcpi_probes = icsk->icsk_probes_out;
3666 	info->tcpi_backoff = icsk->icsk_backoff;
3667 
3668 	if (tp->rx_opt.tstamp_ok)
3669 		info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
3670 	if (tcp_is_sack(tp))
3671 		info->tcpi_options |= TCPI_OPT_SACK;
3672 	if (tp->rx_opt.wscale_ok) {
3673 		info->tcpi_options |= TCPI_OPT_WSCALE;
3674 		info->tcpi_snd_wscale = tp->rx_opt.snd_wscale;
3675 		info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
3676 	}
3677 
3678 	if (tp->ecn_flags & TCP_ECN_OK)
3679 		info->tcpi_options |= TCPI_OPT_ECN;
3680 	if (tp->ecn_flags & TCP_ECN_SEEN)
3681 		info->tcpi_options |= TCPI_OPT_ECN_SEEN;
3682 	if (tp->syn_data_acked)
3683 		info->tcpi_options |= TCPI_OPT_SYN_DATA;
3684 
3685 	info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
3686 	info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);
3687 	info->tcpi_snd_mss = tp->mss_cache;
3688 	info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;
3689 
3690 	info->tcpi_unacked = tp->packets_out;
3691 	info->tcpi_sacked = tp->sacked_out;
3692 
3693 	info->tcpi_lost = tp->lost_out;
3694 	info->tcpi_retrans = tp->retrans_out;
3695 
3696 	now = tcp_jiffies32;
3697 	info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
3698 	info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
3699 	info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);
3700 
3701 	info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
3702 	info->tcpi_rcv_ssthresh = tp->rcv_ssthresh;
3703 	info->tcpi_rtt = tp->srtt_us >> 3;
3704 	info->tcpi_rttvar = tp->mdev_us >> 2;
3705 	info->tcpi_snd_ssthresh = tp->snd_ssthresh;
3706 	info->tcpi_advmss = tp->advmss;
3707 
3708 	info->tcpi_rcv_rtt = tp->rcv_rtt_est.rtt_us >> 3;
3709 	info->tcpi_rcv_space = tp->rcvq_space.space;
3710 
3711 	info->tcpi_total_retrans = tp->total_retrans;
3712 
3713 	info->tcpi_bytes_acked = tp->bytes_acked;
3714 	info->tcpi_bytes_received = tp->bytes_received;
3715 	info->tcpi_notsent_bytes = max_t(int, 0, tp->write_seq - tp->snd_nxt);
3716 	tcp_get_info_chrono_stats(tp, info);
3717 
3718 	info->tcpi_segs_out = tp->segs_out;
3719 	info->tcpi_segs_in = tp->segs_in;
3720 
3721 	info->tcpi_min_rtt = tcp_min_rtt(tp);
3722 	info->tcpi_data_segs_in = tp->data_segs_in;
3723 	info->tcpi_data_segs_out = tp->data_segs_out;
3724 
3725 	info->tcpi_delivery_rate_app_limited = tp->rate_app_limited ? 1 : 0;
3726 	rate64 = tcp_compute_delivery_rate(tp);
3727 	if (rate64)
3728 		info->tcpi_delivery_rate = rate64;
3729 	info->tcpi_delivered = tp->delivered;
3730 	info->tcpi_delivered_ce = tp->delivered_ce;
3731 	info->tcpi_bytes_sent = tp->bytes_sent;
3732 	info->tcpi_bytes_retrans = tp->bytes_retrans;
3733 	info->tcpi_dsack_dups = tp->dsack_dups;
3734 	info->tcpi_reord_seen = tp->reord_seen;
3735 	info->tcpi_rcv_ooopack = tp->rcv_ooopack;
3736 	info->tcpi_snd_wnd = tp->snd_wnd;
3737 	info->tcpi_fastopen_client_fail = tp->fastopen_client_fail;
3738 	unlock_sock_fast(sk, slow);
3739 }
3740 EXPORT_SYMBOL_GPL(tcp_get_info);
3741 
3742 static size_t tcp_opt_stats_get_size(void)
3743 {
3744 	return
3745 		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_BUSY */
3746 		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_RWND_LIMITED */
3747 		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_SNDBUF_LIMITED */
3748 		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_DATA_SEGS_OUT */
3749 		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_TOTAL_RETRANS */
3750 		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_PACING_RATE */
3751 		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_DELIVERY_RATE */
3752 		nla_total_size(sizeof(u32)) + /* TCP_NLA_SND_CWND */
3753 		nla_total_size(sizeof(u32)) + /* TCP_NLA_REORDERING */
3754 		nla_total_size(sizeof(u32)) + /* TCP_NLA_MIN_RTT */
3755 		nla_total_size(sizeof(u8)) + /* TCP_NLA_RECUR_RETRANS */
3756 		nla_total_size(sizeof(u8)) + /* TCP_NLA_DELIVERY_RATE_APP_LMT */
3757 		nla_total_size(sizeof(u32)) + /* TCP_NLA_SNDQ_SIZE */
3758 		nla_total_size(sizeof(u8)) + /* TCP_NLA_CA_STATE */
3759 		nla_total_size(sizeof(u32)) + /* TCP_NLA_SND_SSTHRESH */
3760 		nla_total_size(sizeof(u32)) + /* TCP_NLA_DELIVERED */
3761 		nla_total_size(sizeof(u32)) + /* TCP_NLA_DELIVERED_CE */
3762 		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_BYTES_SENT */
3763 		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_BYTES_RETRANS */
3764 		nla_total_size(sizeof(u32)) + /* TCP_NLA_DSACK_DUPS */
3765 		nla_total_size(sizeof(u32)) + /* TCP_NLA_REORD_SEEN */
3766 		nla_total_size(sizeof(u32)) + /* TCP_NLA_SRTT */
3767 		nla_total_size(sizeof(u16)) + /* TCP_NLA_TIMEOUT_REHASH */
3768 		nla_total_size(sizeof(u32)) + /* TCP_NLA_BYTES_NOTSENT */
3769 		nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_EDT */
3770 		0;
3771 }
3772 
3773 struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk,
3774 					       const struct sk_buff *orig_skb)
3775 {
3776 	const struct tcp_sock *tp = tcp_sk(sk);
3777 	struct sk_buff *stats;
3778 	struct tcp_info info;
3779 	unsigned long rate;
3780 	u64 rate64;
3781 
3782 	stats = alloc_skb(tcp_opt_stats_get_size(), GFP_ATOMIC);
3783 	if (!stats)
3784 		return NULL;
3785 
3786 	tcp_get_info_chrono_stats(tp, &info);
3787 	nla_put_u64_64bit(stats, TCP_NLA_BUSY,
3788 			  info.tcpi_busy_time, TCP_NLA_PAD);
3789 	nla_put_u64_64bit(stats, TCP_NLA_RWND_LIMITED,
3790 			  info.tcpi_rwnd_limited, TCP_NLA_PAD);
3791 	nla_put_u64_64bit(stats, TCP_NLA_SNDBUF_LIMITED,
3792 			  info.tcpi_sndbuf_limited, TCP_NLA_PAD);
3793 	nla_put_u64_64bit(stats, TCP_NLA_DATA_SEGS_OUT,
3794 			  tp->data_segs_out, TCP_NLA_PAD);
3795 	nla_put_u64_64bit(stats, TCP_NLA_TOTAL_RETRANS,
3796 			  tp->total_retrans, TCP_NLA_PAD);
3797 
3798 	rate = READ_ONCE(sk->sk_pacing_rate);
3799 	rate64 = (rate != ~0UL) ? rate : ~0ULL;
3800 	nla_put_u64_64bit(stats, TCP_NLA_PACING_RATE, rate64, TCP_NLA_PAD);
3801 
3802 	rate64 = tcp_compute_delivery_rate(tp);
3803 	nla_put_u64_64bit(stats, TCP_NLA_DELIVERY_RATE, rate64, TCP_NLA_PAD);
3804 
3805 	nla_put_u32(stats, TCP_NLA_SND_CWND, tp->snd_cwnd);
3806 	nla_put_u32(stats, TCP_NLA_REORDERING, tp->reordering);
3807 	nla_put_u32(stats, TCP_NLA_MIN_RTT, tcp_min_rtt(tp));
3808 
3809 	nla_put_u8(stats, TCP_NLA_RECUR_RETRANS, inet_csk(sk)->icsk_retransmits);
3810 	nla_put_u8(stats, TCP_NLA_DELIVERY_RATE_APP_LMT, !!tp->rate_app_limited);
3811 	nla_put_u32(stats, TCP_NLA_SND_SSTHRESH, tp->snd_ssthresh);
3812 	nla_put_u32(stats, TCP_NLA_DELIVERED, tp->delivered);
3813 	nla_put_u32(stats, TCP_NLA_DELIVERED_CE, tp->delivered_ce);
3814 
3815 	nla_put_u32(stats, TCP_NLA_SNDQ_SIZE, tp->write_seq - tp->snd_una);
3816 	nla_put_u8(stats, TCP_NLA_CA_STATE, inet_csk(sk)->icsk_ca_state);
3817 
3818 	nla_put_u64_64bit(stats, TCP_NLA_BYTES_SENT, tp->bytes_sent,
3819 			  TCP_NLA_PAD);
3820 	nla_put_u64_64bit(stats, TCP_NLA_BYTES_RETRANS, tp->bytes_retrans,
3821 			  TCP_NLA_PAD);
3822 	nla_put_u32(stats, TCP_NLA_DSACK_DUPS, tp->dsack_dups);
3823 	nla_put_u32(stats, TCP_NLA_REORD_SEEN, tp->reord_seen);
3824 	nla_put_u32(stats, TCP_NLA_SRTT, tp->srtt_us >> 3);
3825 	nla_put_u16(stats, TCP_NLA_TIMEOUT_REHASH, tp->timeout_rehash);
3826 	nla_put_u32(stats, TCP_NLA_BYTES_NOTSENT,
3827 		    max_t(int, 0, tp->write_seq - tp->snd_nxt));
3828 	nla_put_u64_64bit(stats, TCP_NLA_EDT, orig_skb->skb_mstamp_ns,
3829 			  TCP_NLA_PAD);
3830 
3831 	return stats;
3832 }
3833 
3834 static int do_tcp_getsockopt(struct sock *sk, int level,
3835 		int optname, char __user *optval, int __user *optlen)
3836 {
3837 	struct inet_connection_sock *icsk = inet_csk(sk);
3838 	struct tcp_sock *tp = tcp_sk(sk);
3839 	struct net *net = sock_net(sk);
3840 	int val, len;
3841 
3842 	if (get_user(len, optlen))
3843 		return -EFAULT;
3844 
3845 	len = min_t(unsigned int, len, sizeof(int));
3846 
3847 	if (len < 0)
3848 		return -EINVAL;
3849 
3850 	switch (optname) {
3851 	case TCP_MAXSEG:
3852 		val = tp->mss_cache;
3853 		if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
3854 			val = tp->rx_opt.user_mss;
3855 		if (tp->repair)
3856 			val = tp->rx_opt.mss_clamp;
3857 		break;
3858 	case TCP_NODELAY:
3859 		val = !!(tp->nonagle&TCP_NAGLE_OFF);
3860 		break;
3861 	case TCP_CORK:
3862 		val = !!(tp->nonagle&TCP_NAGLE_CORK);
3863 		break;
3864 	case TCP_KEEPIDLE:
3865 		val = keepalive_time_when(tp) / HZ;
3866 		break;
3867 	case TCP_KEEPINTVL:
3868 		val = keepalive_intvl_when(tp) / HZ;
3869 		break;
3870 	case TCP_KEEPCNT:
3871 		val = keepalive_probes(tp);
3872 		break;
3873 	case TCP_SYNCNT:
3874 		val = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_syn_retries;
3875 		break;
3876 	case TCP_LINGER2:
3877 		val = tp->linger2;
3878 		if (val >= 0)
3879 			val = (val ? : net->ipv4.sysctl_tcp_fin_timeout) / HZ;
3880 		break;
3881 	case TCP_DEFER_ACCEPT:
3882 		val = retrans_to_secs(icsk->icsk_accept_queue.rskq_defer_accept,
3883 				      TCP_TIMEOUT_INIT / HZ, TCP_RTO_MAX / HZ);
3884 		break;
3885 	case TCP_WINDOW_CLAMP:
3886 		val = tp->window_clamp;
3887 		break;
3888 	case TCP_INFO: {
3889 		struct tcp_info info;
3890 
3891 		if (get_user(len, optlen))
3892 			return -EFAULT;
3893 
3894 		tcp_get_info(sk, &info);
3895 
3896 		len = min_t(unsigned int, len, sizeof(info));
3897 		if (put_user(len, optlen))
3898 			return -EFAULT;
3899 		if (copy_to_user(optval, &info, len))
3900 			return -EFAULT;
3901 		return 0;
3902 	}
3903 	case TCP_CC_INFO: {
3904 		const struct tcp_congestion_ops *ca_ops;
3905 		union tcp_cc_info info;
3906 		size_t sz = 0;
3907 		int attr;
3908 
3909 		if (get_user(len, optlen))
3910 			return -EFAULT;
3911 
3912 		ca_ops = icsk->icsk_ca_ops;
3913 		if (ca_ops && ca_ops->get_info)
3914 			sz = ca_ops->get_info(sk, ~0U, &attr, &info);
3915 
3916 		len = min_t(unsigned int, len, sz);
3917 		if (put_user(len, optlen))
3918 			return -EFAULT;
3919 		if (copy_to_user(optval, &info, len))
3920 			return -EFAULT;
3921 		return 0;
3922 	}
3923 	case TCP_QUICKACK:
3924 		val = !inet_csk_in_pingpong_mode(sk);
3925 		break;
3926 
3927 	case TCP_CONGESTION:
3928 		if (get_user(len, optlen))
3929 			return -EFAULT;
3930 		len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
3931 		if (put_user(len, optlen))
3932 			return -EFAULT;
3933 		if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
3934 			return -EFAULT;
3935 		return 0;
3936 
3937 	case TCP_ULP:
3938 		if (get_user(len, optlen))
3939 			return -EFAULT;
3940 		len = min_t(unsigned int, len, TCP_ULP_NAME_MAX);
3941 		if (!icsk->icsk_ulp_ops) {
3942 			if (put_user(0, optlen))
3943 				return -EFAULT;
3944 			return 0;
3945 		}
3946 		if (put_user(len, optlen))
3947 			return -EFAULT;
3948 		if (copy_to_user(optval, icsk->icsk_ulp_ops->name, len))
3949 			return -EFAULT;
3950 		return 0;
3951 
3952 	case TCP_FASTOPEN_KEY: {
3953 		u64 key[TCP_FASTOPEN_KEY_BUF_LENGTH / sizeof(u64)];
3954 		unsigned int key_len;
3955 
3956 		if (get_user(len, optlen))
3957 			return -EFAULT;
3958 
3959 		key_len = tcp_fastopen_get_cipher(net, icsk, key) *
3960 				TCP_FASTOPEN_KEY_LENGTH;
3961 		len = min_t(unsigned int, len, key_len);
3962 		if (put_user(len, optlen))
3963 			return -EFAULT;
3964 		if (copy_to_user(optval, key, len))
3965 			return -EFAULT;
3966 		return 0;
3967 	}
3968 	case TCP_THIN_LINEAR_TIMEOUTS:
3969 		val = tp->thin_lto;
3970 		break;
3971 
3972 	case TCP_THIN_DUPACK:
3973 		val = 0;
3974 		break;
3975 
3976 	case TCP_REPAIR:
3977 		val = tp->repair;
3978 		break;
3979 
3980 	case TCP_REPAIR_QUEUE:
3981 		if (tp->repair)
3982 			val = tp->repair_queue;
3983 		else
3984 			return -EINVAL;
3985 		break;
3986 
3987 	case TCP_REPAIR_WINDOW: {
3988 		struct tcp_repair_window opt;
3989 
3990 		if (get_user(len, optlen))
3991 			return -EFAULT;
3992 
3993 		if (len != sizeof(opt))
3994 			return -EINVAL;
3995 
3996 		if (!tp->repair)
3997 			return -EPERM;
3998 
3999 		opt.snd_wl1	= tp->snd_wl1;
4000 		opt.snd_wnd	= tp->snd_wnd;
4001 		opt.max_window	= tp->max_window;
4002 		opt.rcv_wnd	= tp->rcv_wnd;
4003 		opt.rcv_wup	= tp->rcv_wup;
4004 
4005 		if (copy_to_user(optval, &opt, len))
4006 			return -EFAULT;
4007 		return 0;
4008 	}
4009 	case TCP_QUEUE_SEQ:
4010 		if (tp->repair_queue == TCP_SEND_QUEUE)
4011 			val = tp->write_seq;
4012 		else if (tp->repair_queue == TCP_RECV_QUEUE)
4013 			val = tp->rcv_nxt;
4014 		else
4015 			return -EINVAL;
4016 		break;
4017 
4018 	case TCP_USER_TIMEOUT:
4019 		val = icsk->icsk_user_timeout;
4020 		break;
4021 
4022 	case TCP_FASTOPEN:
4023 		val = icsk->icsk_accept_queue.fastopenq.max_qlen;
4024 		break;
4025 
4026 	case TCP_FASTOPEN_CONNECT:
4027 		val = tp->fastopen_connect;
4028 		break;
4029 
4030 	case TCP_FASTOPEN_NO_COOKIE:
4031 		val = tp->fastopen_no_cookie;
4032 		break;
4033 
4034 	case TCP_TX_DELAY:
4035 		val = tp->tcp_tx_delay;
4036 		break;
4037 
4038 	case TCP_TIMESTAMP:
4039 		val = tcp_time_stamp_raw() + tp->tsoffset;
4040 		break;
4041 	case TCP_NOTSENT_LOWAT:
4042 		val = tp->notsent_lowat;
4043 		break;
4044 	case TCP_INQ:
4045 		val = tp->recvmsg_inq;
4046 		break;
4047 	case TCP_SAVE_SYN:
4048 		val = tp->save_syn;
4049 		break;
4050 	case TCP_SAVED_SYN: {
4051 		if (get_user(len, optlen))
4052 			return -EFAULT;
4053 
4054 		lock_sock(sk);
4055 		if (tp->saved_syn) {
4056 			if (len < tcp_saved_syn_len(tp->saved_syn)) {
4057 				if (put_user(tcp_saved_syn_len(tp->saved_syn),
4058 					     optlen)) {
4059 					release_sock(sk);
4060 					return -EFAULT;
4061 				}
4062 				release_sock(sk);
4063 				return -EINVAL;
4064 			}
4065 			len = tcp_saved_syn_len(tp->saved_syn);
4066 			if (put_user(len, optlen)) {
4067 				release_sock(sk);
4068 				return -EFAULT;
4069 			}
4070 			if (copy_to_user(optval, tp->saved_syn->data, len)) {
4071 				release_sock(sk);
4072 				return -EFAULT;
4073 			}
4074 			tcp_saved_syn_free(tp);
4075 			release_sock(sk);
4076 		} else {
4077 			release_sock(sk);
4078 			len = 0;
4079 			if (put_user(len, optlen))
4080 				return -EFAULT;
4081 		}
4082 		return 0;
4083 	}
4084 #ifdef CONFIG_MMU
4085 	case TCP_ZEROCOPY_RECEIVE: {
4086 		struct tcp_zerocopy_receive zc = {};
4087 		int err;
4088 
4089 		if (get_user(len, optlen))
4090 			return -EFAULT;
4091 		if (len < offsetofend(struct tcp_zerocopy_receive, length))
4092 			return -EINVAL;
4093 		if (len > sizeof(zc)) {
4094 			len = sizeof(zc);
4095 			if (put_user(len, optlen))
4096 				return -EFAULT;
4097 		}
4098 		if (copy_from_user(&zc, optval, len))
4099 			return -EFAULT;
4100 		lock_sock(sk);
4101 		err = tcp_zerocopy_receive(sk, &zc);
4102 		release_sock(sk);
4103 		if (len >= offsetofend(struct tcp_zerocopy_receive, err))
4104 			goto zerocopy_rcv_sk_err;
4105 		switch (len) {
4106 		case offsetofend(struct tcp_zerocopy_receive, err):
4107 			goto zerocopy_rcv_sk_err;
4108 		case offsetofend(struct tcp_zerocopy_receive, inq):
4109 			goto zerocopy_rcv_inq;
4110 		case offsetofend(struct tcp_zerocopy_receive, length):
4111 		default:
4112 			goto zerocopy_rcv_out;
4113 		}
4114 zerocopy_rcv_sk_err:
4115 		if (!err)
4116 			zc.err = sock_error(sk);
4117 zerocopy_rcv_inq:
4118 		zc.inq = tcp_inq_hint(sk);
4119 zerocopy_rcv_out:
4120 		if (!err && copy_to_user(optval, &zc, len))
4121 			err = -EFAULT;
4122 		return err;
4123 	}
4124 #endif
4125 	default:
4126 		return -ENOPROTOOPT;
4127 	}
4128 
4129 	if (put_user(len, optlen))
4130 		return -EFAULT;
4131 	if (copy_to_user(optval, &val, len))
4132 		return -EFAULT;
4133 	return 0;
4134 }
4135 
4136 int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
4137 		   int __user *optlen)
4138 {
4139 	struct inet_connection_sock *icsk = inet_csk(sk);
4140 
4141 	if (level != SOL_TCP)
4142 		return icsk->icsk_af_ops->getsockopt(sk, level, optname,
4143 						     optval, optlen);
4144 	return do_tcp_getsockopt(sk, level, optname, optval, optlen);
4145 }
4146 EXPORT_SYMBOL(tcp_getsockopt);
4147 
4148 #ifdef CONFIG_TCP_MD5SIG
4149 static DEFINE_PER_CPU(struct tcp_md5sig_pool, tcp_md5sig_pool);
4150 static DEFINE_MUTEX(tcp_md5sig_mutex);
4151 static bool tcp_md5sig_pool_populated = false;
4152 
4153 static void __tcp_alloc_md5sig_pool(void)
4154 {
4155 	struct crypto_ahash *hash;
4156 	int cpu;
4157 
4158 	hash = crypto_alloc_ahash("md5", 0, CRYPTO_ALG_ASYNC);
4159 	if (IS_ERR(hash))
4160 		return;
4161 
4162 	for_each_possible_cpu(cpu) {
4163 		void *scratch = per_cpu(tcp_md5sig_pool, cpu).scratch;
4164 		struct ahash_request *req;
4165 
4166 		if (!scratch) {
4167 			scratch = kmalloc_node(sizeof(union tcp_md5sum_block) +
4168 					       sizeof(struct tcphdr),
4169 					       GFP_KERNEL,
4170 					       cpu_to_node(cpu));
4171 			if (!scratch)
4172 				return;
4173 			per_cpu(tcp_md5sig_pool, cpu).scratch = scratch;
4174 		}
4175 		if (per_cpu(tcp_md5sig_pool, cpu).md5_req)
4176 			continue;
4177 
4178 		req = ahash_request_alloc(hash, GFP_KERNEL);
4179 		if (!req)
4180 			return;
4181 
4182 		ahash_request_set_callback(req, 0, NULL, NULL);
4183 
4184 		per_cpu(tcp_md5sig_pool, cpu).md5_req = req;
4185 	}
4186 	/* before setting tcp_md5sig_pool_populated, we must commit all writes
4187 	 * to memory. See smp_rmb() in tcp_get_md5sig_pool()
4188 	 */
4189 	smp_wmb();
4190 	tcp_md5sig_pool_populated = true;
4191 }
4192 
4193 bool tcp_alloc_md5sig_pool(void)
4194 {
4195 	if (unlikely(!tcp_md5sig_pool_populated)) {
4196 		mutex_lock(&tcp_md5sig_mutex);
4197 
4198 		if (!tcp_md5sig_pool_populated) {
4199 			__tcp_alloc_md5sig_pool();
4200 			if (tcp_md5sig_pool_populated)
4201 				static_branch_inc(&tcp_md5_needed);
4202 		}
4203 
4204 		mutex_unlock(&tcp_md5sig_mutex);
4205 	}
4206 	return tcp_md5sig_pool_populated;
4207 }
4208 EXPORT_SYMBOL(tcp_alloc_md5sig_pool);
4209 
4210 
4211 /**
4212  *	tcp_get_md5sig_pool - get md5sig_pool for this user
4213  *
4214  *	We use percpu structure, so if we succeed, we exit with preemption
4215  *	and BH disabled, to make sure another thread or softirq handling
4216  *	wont try to get same context.
4217  */
4218 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void)
4219 {
4220 	local_bh_disable();
4221 
4222 	if (tcp_md5sig_pool_populated) {
4223 		/* coupled with smp_wmb() in __tcp_alloc_md5sig_pool() */
4224 		smp_rmb();
4225 		return this_cpu_ptr(&tcp_md5sig_pool);
4226 	}
4227 	local_bh_enable();
4228 	return NULL;
4229 }
4230 EXPORT_SYMBOL(tcp_get_md5sig_pool);
4231 
4232 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *hp,
4233 			  const struct sk_buff *skb, unsigned int header_len)
4234 {
4235 	struct scatterlist sg;
4236 	const struct tcphdr *tp = tcp_hdr(skb);
4237 	struct ahash_request *req = hp->md5_req;
4238 	unsigned int i;
4239 	const unsigned int head_data_len = skb_headlen(skb) > header_len ?
4240 					   skb_headlen(skb) - header_len : 0;
4241 	const struct skb_shared_info *shi = skb_shinfo(skb);
4242 	struct sk_buff *frag_iter;
4243 
4244 	sg_init_table(&sg, 1);
4245 
4246 	sg_set_buf(&sg, ((u8 *) tp) + header_len, head_data_len);
4247 	ahash_request_set_crypt(req, &sg, NULL, head_data_len);
4248 	if (crypto_ahash_update(req))
4249 		return 1;
4250 
4251 	for (i = 0; i < shi->nr_frags; ++i) {
4252 		const skb_frag_t *f = &shi->frags[i];
4253 		unsigned int offset = skb_frag_off(f);
4254 		struct page *page = skb_frag_page(f) + (offset >> PAGE_SHIFT);
4255 
4256 		sg_set_page(&sg, page, skb_frag_size(f),
4257 			    offset_in_page(offset));
4258 		ahash_request_set_crypt(req, &sg, NULL, skb_frag_size(f));
4259 		if (crypto_ahash_update(req))
4260 			return 1;
4261 	}
4262 
4263 	skb_walk_frags(skb, frag_iter)
4264 		if (tcp_md5_hash_skb_data(hp, frag_iter, 0))
4265 			return 1;
4266 
4267 	return 0;
4268 }
4269 EXPORT_SYMBOL(tcp_md5_hash_skb_data);
4270 
4271 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, const struct tcp_md5sig_key *key)
4272 {
4273 	u8 keylen = READ_ONCE(key->keylen); /* paired with WRITE_ONCE() in tcp_md5_do_add */
4274 	struct scatterlist sg;
4275 
4276 	sg_init_one(&sg, key->key, keylen);
4277 	ahash_request_set_crypt(hp->md5_req, &sg, NULL, keylen);
4278 
4279 	/* We use data_race() because tcp_md5_do_add() might change key->key under us */
4280 	return data_race(crypto_ahash_update(hp->md5_req));
4281 }
4282 EXPORT_SYMBOL(tcp_md5_hash_key);
4283 
4284 #endif
4285 
4286 void tcp_done(struct sock *sk)
4287 {
4288 	struct request_sock *req;
4289 
4290 	/* We might be called with a new socket, after
4291 	 * inet_csk_prepare_forced_close() has been called
4292 	 * so we can not use lockdep_sock_is_held(sk)
4293 	 */
4294 	req = rcu_dereference_protected(tcp_sk(sk)->fastopen_rsk, 1);
4295 
4296 	if (sk->sk_state == TCP_SYN_SENT || sk->sk_state == TCP_SYN_RECV)
4297 		TCP_INC_STATS(sock_net(sk), TCP_MIB_ATTEMPTFAILS);
4298 
4299 	tcp_set_state(sk, TCP_CLOSE);
4300 	tcp_clear_xmit_timers(sk);
4301 	if (req)
4302 		reqsk_fastopen_remove(sk, req, false);
4303 
4304 	sk->sk_shutdown = SHUTDOWN_MASK;
4305 
4306 	if (!sock_flag(sk, SOCK_DEAD))
4307 		sk->sk_state_change(sk);
4308 	else
4309 		inet_csk_destroy_sock(sk);
4310 }
4311 EXPORT_SYMBOL_GPL(tcp_done);
4312 
4313 int tcp_abort(struct sock *sk, int err)
4314 {
4315 	if (!sk_fullsock(sk)) {
4316 		if (sk->sk_state == TCP_NEW_SYN_RECV) {
4317 			struct request_sock *req = inet_reqsk(sk);
4318 
4319 			local_bh_disable();
4320 			inet_csk_reqsk_queue_drop(req->rsk_listener, req);
4321 			local_bh_enable();
4322 			return 0;
4323 		}
4324 		return -EOPNOTSUPP;
4325 	}
4326 
4327 	/* Don't race with userspace socket closes such as tcp_close. */
4328 	lock_sock(sk);
4329 
4330 	if (sk->sk_state == TCP_LISTEN) {
4331 		tcp_set_state(sk, TCP_CLOSE);
4332 		inet_csk_listen_stop(sk);
4333 	}
4334 
4335 	/* Don't race with BH socket closes such as inet_csk_listen_stop. */
4336 	local_bh_disable();
4337 	bh_lock_sock(sk);
4338 
4339 	if (!sock_flag(sk, SOCK_DEAD)) {
4340 		sk->sk_err = err;
4341 		/* This barrier is coupled with smp_rmb() in tcp_poll() */
4342 		smp_wmb();
4343 		sk->sk_error_report(sk);
4344 		if (tcp_need_reset(sk->sk_state))
4345 			tcp_send_active_reset(sk, GFP_ATOMIC);
4346 		tcp_done(sk);
4347 	}
4348 
4349 	bh_unlock_sock(sk);
4350 	local_bh_enable();
4351 	tcp_write_queue_purge(sk);
4352 	release_sock(sk);
4353 	return 0;
4354 }
4355 EXPORT_SYMBOL_GPL(tcp_abort);
4356 
4357 extern struct tcp_congestion_ops tcp_reno;
4358 
4359 static __initdata unsigned long thash_entries;
4360 static int __init set_thash_entries(char *str)
4361 {
4362 	ssize_t ret;
4363 
4364 	if (!str)
4365 		return 0;
4366 
4367 	ret = kstrtoul(str, 0, &thash_entries);
4368 	if (ret)
4369 		return 0;
4370 
4371 	return 1;
4372 }
4373 __setup("thash_entries=", set_thash_entries);
4374 
4375 static void __init tcp_init_mem(void)
4376 {
4377 	unsigned long limit = nr_free_buffer_pages() / 16;
4378 
4379 	limit = max(limit, 128UL);
4380 	sysctl_tcp_mem[0] = limit / 4 * 3;		/* 4.68 % */
4381 	sysctl_tcp_mem[1] = limit;			/* 6.25 % */
4382 	sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2;	/* 9.37 % */
4383 }
4384 
4385 void __init tcp_init(void)
4386 {
4387 	int max_rshare, max_wshare, cnt;
4388 	unsigned long limit;
4389 	unsigned int i;
4390 
4391 	BUILD_BUG_ON(TCP_MIN_SND_MSS <= MAX_TCP_OPTION_SPACE);
4392 	BUILD_BUG_ON(sizeof(struct tcp_skb_cb) >
4393 		     sizeof_field(struct sk_buff, cb));
4394 
4395 	percpu_counter_init(&tcp_sockets_allocated, 0, GFP_KERNEL);
4396 	percpu_counter_init(&tcp_orphan_count, 0, GFP_KERNEL);
4397 	inet_hashinfo_init(&tcp_hashinfo);
4398 	inet_hashinfo2_init(&tcp_hashinfo, "tcp_listen_portaddr_hash",
4399 			    thash_entries, 21,  /* one slot per 2 MB*/
4400 			    0, 64 * 1024);
4401 	tcp_hashinfo.bind_bucket_cachep =
4402 		kmem_cache_create("tcp_bind_bucket",
4403 				  sizeof(struct inet_bind_bucket), 0,
4404 				  SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
4405 
4406 	/* Size and allocate the main established and bind bucket
4407 	 * hash tables.
4408 	 *
4409 	 * The methodology is similar to that of the buffer cache.
4410 	 */
4411 	tcp_hashinfo.ehash =
4412 		alloc_large_system_hash("TCP established",
4413 					sizeof(struct inet_ehash_bucket),
4414 					thash_entries,
4415 					17, /* one slot per 128 KB of memory */
4416 					0,
4417 					NULL,
4418 					&tcp_hashinfo.ehash_mask,
4419 					0,
4420 					thash_entries ? 0 : 512 * 1024);
4421 	for (i = 0; i <= tcp_hashinfo.ehash_mask; i++)
4422 		INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].chain, i);
4423 
4424 	if (inet_ehash_locks_alloc(&tcp_hashinfo))
4425 		panic("TCP: failed to alloc ehash_locks");
4426 	tcp_hashinfo.bhash =
4427 		alloc_large_system_hash("TCP bind",
4428 					sizeof(struct inet_bind_hashbucket),
4429 					tcp_hashinfo.ehash_mask + 1,
4430 					17, /* one slot per 128 KB of memory */
4431 					0,
4432 					&tcp_hashinfo.bhash_size,
4433 					NULL,
4434 					0,
4435 					64 * 1024);
4436 	tcp_hashinfo.bhash_size = 1U << tcp_hashinfo.bhash_size;
4437 	for (i = 0; i < tcp_hashinfo.bhash_size; i++) {
4438 		spin_lock_init(&tcp_hashinfo.bhash[i].lock);
4439 		INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain);
4440 	}
4441 
4442 
4443 	cnt = tcp_hashinfo.ehash_mask + 1;
4444 	sysctl_tcp_max_orphans = cnt / 2;
4445 
4446 	tcp_init_mem();
4447 	/* Set per-socket limits to no more than 1/128 the pressure threshold */
4448 	limit = nr_free_buffer_pages() << (PAGE_SHIFT - 7);
4449 	max_wshare = min(4UL*1024*1024, limit);
4450 	max_rshare = min(6UL*1024*1024, limit);
4451 
4452 	init_net.ipv4.sysctl_tcp_wmem[0] = SK_MEM_QUANTUM;
4453 	init_net.ipv4.sysctl_tcp_wmem[1] = 16*1024;
4454 	init_net.ipv4.sysctl_tcp_wmem[2] = max(64*1024, max_wshare);
4455 
4456 	init_net.ipv4.sysctl_tcp_rmem[0] = SK_MEM_QUANTUM;
4457 	init_net.ipv4.sysctl_tcp_rmem[1] = 131072;
4458 	init_net.ipv4.sysctl_tcp_rmem[2] = max(131072, max_rshare);
4459 
4460 	pr_info("Hash tables configured (established %u bind %u)\n",
4461 		tcp_hashinfo.ehash_mask + 1, tcp_hashinfo.bhash_size);
4462 
4463 	tcp_v4_init();
4464 	tcp_metrics_init();
4465 	BUG_ON(tcp_register_congestion_control(&tcp_reno) != 0);
4466 	tcp_tasklet_init();
4467 	mptcp_init();
4468 }
4469