1	// SPDX-License-Identifier: GPL-2.0
2	/* Multipath TCP
3	*
4	* Copyright (c) 2017 - 2019, Intel Corporation.
5	*/
6
7	#define pr_fmt(fmt) "MPTCP: " fmt
8
9	#include <linux/kernel.h>
10	#include <linux/module.h>
11	#include <linux/netdevice.h>
12	#include <linux/sched/signal.h>
13	#include <linux/atomic.h>
14	#include <net/sock.h>
15	#include <net/inet_common.h>
16	#include <net/inet_hashtables.h>
17	#include <net/protocol.h>
18	#include <net/tcp_states.h>
19	#if IS_ENABLED(CONFIG_MPTCP_IPV6)
20	#include <net/transp_v6.h>
21	#endif
22	#include <net/mptcp.h>
23	#include <net/xfrm.h>
24	#include <asm/ioctls.h>
25	#include "protocol.h"
26	#include "mib.h"
27
28	#define CREATE_TRACE_POINTS
29	#include <trace/events/mptcp.h>
30
31	#if IS_ENABLED(CONFIG_MPTCP_IPV6)
32	struct mptcp6_sock {
33	struct mptcp_sock msk;
34	struct ipv6_pinfo np;
35	};
36	#endif
37
38	enum {
39	MPTCP_CMSG_TS = BIT(0),
40	MPTCP_CMSG_INQ = BIT(1),
41	};
42
43	static struct percpu_counter mptcp_sockets_allocated ____cacheline_aligned_in_smp;
44
45	static void __mptcp_destroy_sock(struct sock *sk);
46	static void mptcp_check_send_data_fin(struct sock *sk);
47
48	DEFINE_PER_CPU(struct mptcp_delegated_action, mptcp_delegated_actions);
49	static struct net_device mptcp_napi_dev;
50
51	/* Returns end sequence number of the receiver's advertised window */
52	static u64 mptcp_wnd_end(const struct mptcp_sock *msk)
53	{
54	return READ_ONCE(msk->wnd_end);
55	}
56
57	static const struct proto_ops *mptcp_fallback_tcp_ops(const struct sock *sk)
58	{
59	#if IS_ENABLED(CONFIG_MPTCP_IPV6)
60	if (sk->sk_prot == &tcpv6_prot)
61	return &inet6_stream_ops;
62	#endif
63	WARN_ON_ONCE(sk->sk_prot != &tcp_prot);
64	return &inet_stream_ops;
65	}
66
67	static int __mptcp_socket_create(struct mptcp_sock *msk)
68	{
69	struct mptcp_subflow_context *subflow;
70	struct sock *sk = (struct sock *)msk;
71	struct socket *ssock;
72	int err;
73
74	err = mptcp_subflow_create_socket(sk, family: sk->sk_family, new_sock: &ssock);
75	if (err)
76	return err;
77
78	msk->scaling_ratio = tcp_sk(ssock->sk)->scaling_ratio;
79	WRITE_ONCE(msk->first, ssock->sk);
80	subflow = mptcp_subflow_ctx(sk: ssock->sk);
81	list_add(new: &subflow->node, head: &msk->conn_list);
82	sock_hold(sk: ssock->sk);
83	subflow->request_mptcp = 1;
84	subflow->subflow_id = msk->subflow_id++;
85
86	/* This is the first subflow, always with id 0 */
87	WRITE_ONCE(subflow->local_id, 0);
88	mptcp_sock_graft(sk: msk->first, parent: sk->sk_socket);
89	iput(SOCK_INODE(socket: ssock));
90
91	return 0;
92	}
93
94	/* If the MPC handshake is not started, returns the first subflow,
95	* eventually allocating it.
96	*/
97	struct sock *__mptcp_nmpc_sk(struct mptcp_sock *msk)
98	{
99	struct sock *sk = (struct sock *)msk;
100	int ret;
101
102	if (!((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
103	return ERR_PTR(error: -EINVAL);
104
105	if (!msk->first) {
106	ret = __mptcp_socket_create(msk);
107	if (ret)
108	return ERR_PTR(error: ret);
109	}
110
111	return msk->first;
112	}
113
114	static void mptcp_drop(struct sock *sk, struct sk_buff *skb)
115	{
116	sk_drops_add(sk, skb);
117	__kfree_skb(skb);
118	}
119
120	static void mptcp_rmem_fwd_alloc_add(struct sock *sk, int size)
121	{
122	WRITE_ONCE(mptcp_sk(sk)->rmem_fwd_alloc,
123	mptcp_sk(sk)->rmem_fwd_alloc + size);
124	}
125
126	static void mptcp_rmem_charge(struct sock *sk, int size)
127	{
128	mptcp_rmem_fwd_alloc_add(sk, size: -size);
129	}
130
131	static bool mptcp_try_coalesce(struct sock *sk, struct sk_buff *to,
132	struct sk_buff *from)
133	{
134	bool fragstolen;
135	int delta;
136
137	if (MPTCP_SKB_CB(from)->offset ||
138	!skb_try_coalesce(to, from, fragstolen: &fragstolen, delta_truesize: &delta))
139	return false;
140
141	pr_debug("colesced seq %llx into %llx new len %d new end seq %llx",
142	MPTCP_SKB_CB(from)->map_seq, MPTCP_SKB_CB(to)->map_seq,
143	to->len, MPTCP_SKB_CB(from)->end_seq);
144	MPTCP_SKB_CB(to)->end_seq = MPTCP_SKB_CB(from)->end_seq;
145
146	/* note the fwd memory can reach a negative value after accounting
147	* for the delta, but the later skb free will restore a non
148	* negative one
149	*/
150	atomic_add(i: delta, v: &sk->sk_rmem_alloc);
151	mptcp_rmem_charge(sk, size: delta);
152	kfree_skb_partial(skb: from, head_stolen: fragstolen);
153
154	return true;
155	}
156
157	static bool mptcp_ooo_try_coalesce(struct mptcp_sock *msk, struct sk_buff *to,
158	struct sk_buff *from)
159	{
160	if (MPTCP_SKB_CB(from)->map_seq != MPTCP_SKB_CB(to)->end_seq)
161	return false;
162
163	return mptcp_try_coalesce(sk: (struct sock *)msk, to, from);
164	}
165
166	static void __mptcp_rmem_reclaim(struct sock *sk, int amount)
167	{
168	amount >>= PAGE_SHIFT;
169	mptcp_rmem_charge(sk, size: amount << PAGE_SHIFT);
170	__sk_mem_reduce_allocated(sk, amount);
171	}
172
173	static void mptcp_rmem_uncharge(struct sock *sk, int size)
174	{
175	struct mptcp_sock *msk = mptcp_sk(sk);
176	int reclaimable;
177
178	mptcp_rmem_fwd_alloc_add(sk, size);
179	reclaimable = msk->rmem_fwd_alloc - sk_unused_reserved_mem(sk);
180
181	/* see sk_mem_uncharge() for the rationale behind the following schema */
182	if (unlikely(reclaimable >= PAGE_SIZE))
183	__mptcp_rmem_reclaim(sk, amount: reclaimable);
184	}
185
186	static void mptcp_rfree(struct sk_buff *skb)
187	{
188	unsigned int len = skb->truesize;
189	struct sock *sk = skb->sk;
190
191	atomic_sub(i: len, v: &sk->sk_rmem_alloc);
192	mptcp_rmem_uncharge(sk, size: len);
193	}
194
195	void mptcp_set_owner_r(struct sk_buff *skb, struct sock *sk)
196	{
197	skb_orphan(skb);
198	skb->sk = sk;
199	skb->destructor = mptcp_rfree;
200	atomic_add(i: skb->truesize, v: &sk->sk_rmem_alloc);
201	mptcp_rmem_charge(sk, size: skb->truesize);
202	}
203
204	/* "inspired" by tcp_data_queue_ofo(), main differences:
205	* - use mptcp seqs
206	* - don't cope with sacks
207	*/
208	static void mptcp_data_queue_ofo(struct mptcp_sock *msk, struct sk_buff *skb)
209	{
210	struct sock *sk = (struct sock *)msk;
211	struct rb_node **p, *parent;
212	u64 seq, end_seq, max_seq;
213	struct sk_buff *skb1;
214
215	seq = MPTCP_SKB_CB(skb)->map_seq;
216	end_seq = MPTCP_SKB_CB(skb)->end_seq;
217	max_seq = atomic64_read(v: &msk->rcv_wnd_sent);
218
219	pr_debug("msk=%p seq=%llx limit=%llx empty=%d", msk, seq, max_seq,
220	RB_EMPTY_ROOT(&msk->out_of_order_queue));
221	if (after64(end_seq, max_seq)) {
222	/* out of window */
223	mptcp_drop(sk, skb);
224	pr_debug("oow by %lld, rcv_wnd_sent %llu\n",
225	(unsigned long long)end_seq - (unsigned long)max_seq,
226	(unsigned long long)atomic64_read(&msk->rcv_wnd_sent));
227	MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_NODSSWINDOW);
228	return;
229	}
230
231	p = &msk->out_of_order_queue.rb_node;
232	MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_OFOQUEUE);
233	if (RB_EMPTY_ROOT(&msk->out_of_order_queue)) {
234	rb_link_node(node: &skb->rbnode, NULL, rb_link: p);
235	rb_insert_color(&skb->rbnode, &msk->out_of_order_queue);
236	msk->ooo_last_skb = skb;
237	goto end;
238	}
239
240	/* with 2 subflows, adding at end of ooo queue is quite likely
241	* Use of ooo_last_skb avoids the O(Log(N)) rbtree lookup.
242	*/
243	if (mptcp_ooo_try_coalesce(msk, to: msk->ooo_last_skb, from: skb)) {
244	MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_OFOMERGE);
245	MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_OFOQUEUETAIL);
246	return;
247	}
248
249	/* Can avoid an rbtree lookup if we are adding skb after ooo_last_skb */
250	if (!before64(seq1: seq, MPTCP_SKB_CB(msk->ooo_last_skb)->end_seq)) {
251	MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_OFOQUEUETAIL);
252	parent = &msk->ooo_last_skb->rbnode;
253	p = &parent->rb_right;
254	goto insert;
255	}
256
257	/* Find place to insert this segment. Handle overlaps on the way. */
258	parent = NULL;
259	while (*p) {
260	parent = *p;
261	skb1 = rb_to_skb(parent);
262	if (before64(seq1: seq, MPTCP_SKB_CB(skb1)->map_seq)) {
263	p = &parent->rb_left;
264	continue;
265	}
266	if (before64(seq1: seq, MPTCP_SKB_CB(skb1)->end_seq)) {
267	if (!after64(end_seq, MPTCP_SKB_CB(skb1)->end_seq)) {
268	/* All the bits are present. Drop. */
269	mptcp_drop(sk, skb);
270	MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_DUPDATA);
271	return;
272	}
273	if (after64(seq, MPTCP_SKB_CB(skb1)->map_seq)) {
274	/* partial overlap:
275	* | skb |
276	* | skb1 |
277	* continue traversing
278	*/
279	} else {
280	/* skb's seq == skb1's seq and skb covers skb1.
281	* Replace skb1 with skb.
282	*/
283	rb_replace_node(victim: &skb1->rbnode, new: &skb->rbnode,
284	root: &msk->out_of_order_queue);
285	mptcp_drop(sk, skb: skb1);
286	MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_DUPDATA);
287	goto merge_right;
288	}
289	} else if (mptcp_ooo_try_coalesce(msk, to: skb1, from: skb)) {
290	MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_OFOMERGE);
291	return;
292	}
293	p = &parent->rb_right;
294	}
295
296	insert:
297	/* Insert segment into RB tree. */
298	rb_link_node(node: &skb->rbnode, parent, rb_link: p);
299	rb_insert_color(&skb->rbnode, &msk->out_of_order_queue);
300
301	merge_right:
302	/* Remove other segments covered by skb. */
303	while ((skb1 = skb_rb_next(skb)) != NULL) {
304	if (before64(seq1: end_seq, MPTCP_SKB_CB(skb1)->end_seq))
305	break;
306	rb_erase(&skb1->rbnode, &msk->out_of_order_queue);
307	mptcp_drop(sk, skb: skb1);
308	MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_DUPDATA);
309	}
310	/* If there is no skb after us, we are the last_skb ! */
311	if (!skb1)
312	msk->ooo_last_skb = skb;
313
314	end:
315	skb_condense(skb);
316	mptcp_set_owner_r(skb, sk);
317	}
318
319	static bool mptcp_rmem_schedule(struct sock *sk, struct sock *ssk, int size)
320	{
321	struct mptcp_sock *msk = mptcp_sk(sk);
322	int amt, amount;
323
324	if (size <= msk->rmem_fwd_alloc)
325	return true;
326
327	size -= msk->rmem_fwd_alloc;
328	amt = sk_mem_pages(amt: size);
329	amount = amt << PAGE_SHIFT;
330	if (!__sk_mem_raise_allocated(sk, size, amt, SK_MEM_RECV))
331	return false;
332
333	mptcp_rmem_fwd_alloc_add(sk, size: amount);
334	return true;
335	}
336
337	static bool __mptcp_move_skb(struct mptcp_sock *msk, struct sock *ssk,
338	struct sk_buff *skb, unsigned int offset,
339	size_t copy_len)
340	{
341	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk: ssk);
342	struct sock *sk = (struct sock *)msk;
343	struct sk_buff *tail;
344	bool has_rxtstamp;
345
346	__skb_unlink(skb, list: &ssk->sk_receive_queue);
347
348	skb_ext_reset(skb);
349	skb_orphan(skb);
350
351	/* try to fetch required memory from subflow */
352	if (!mptcp_rmem_schedule(sk, ssk, size: skb->truesize))
353	goto drop;
354
355	has_rxtstamp = TCP_SKB_CB(skb)->has_rxtstamp;
356
357	/* the skb map_seq accounts for the skb offset:
358	* mptcp_subflow_get_mapped_dsn() is based on the current tp->copied_seq
359	* value
360	*/
361	MPTCP_SKB_CB(skb)->map_seq = mptcp_subflow_get_mapped_dsn(subflow);
362	MPTCP_SKB_CB(skb)->end_seq = MPTCP_SKB_CB(skb)->map_seq + copy_len;
363	MPTCP_SKB_CB(skb)->offset = offset;
364	MPTCP_SKB_CB(skb)->has_rxtstamp = has_rxtstamp;
365
366	if (MPTCP_SKB_CB(skb)->map_seq == msk->ack_seq) {
367	/* in sequence */
368	msk->bytes_received += copy_len;
369	WRITE_ONCE(msk->ack_seq, msk->ack_seq + copy_len);
370	tail = skb_peek_tail(list_: &sk->sk_receive_queue);
371	if (tail && mptcp_try_coalesce(sk, to: tail, from: skb))
372	return true;
373
374	mptcp_set_owner_r(skb, sk);
375	__skb_queue_tail(list: &sk->sk_receive_queue, newsk: skb);
376	return true;
377	} else if (after64(MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq)) {
378	mptcp_data_queue_ofo(msk, skb);
379	return false;
380	}
381
382	/* old data, keep it simple and drop the whole pkt, sender
383	* will retransmit as needed, if needed.
384	*/
385	MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_DUPDATA);
386	drop:
387	mptcp_drop(sk, skb);
388	return false;
389	}
390
391	static void mptcp_stop_rtx_timer(struct sock *sk)
392	{
393	struct inet_connection_sock *icsk = inet_csk(sk);
394
395	sk_stop_timer(sk, timer: &icsk->icsk_retransmit_timer);
396	mptcp_sk(sk)->timer_ival = 0;
397	}
398
399	static void mptcp_close_wake_up(struct sock *sk)
400	{
401	if (sock_flag(sk, flag: SOCK_DEAD))
402	return;
403
404	sk->sk_state_change(sk);
405	if (sk->sk_shutdown == SHUTDOWN_MASK ||
406	sk->sk_state == TCP_CLOSE)
407	sk_wake_async(sk, how: SOCK_WAKE_WAITD, POLL_HUP);
408	else
409	sk_wake_async(sk, how: SOCK_WAKE_WAITD, POLL_IN);
410	}
411
412	/* called under the msk socket lock */
413	static bool mptcp_pending_data_fin_ack(struct sock *sk)
414	{
415	struct mptcp_sock *msk = mptcp_sk(sk);
416
417	return ((1 << sk->sk_state) &
418	(TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK)) &&
419	msk->write_seq == READ_ONCE(msk->snd_una);
420	}
421
422	static void mptcp_check_data_fin_ack(struct sock *sk)
423	{
424	struct mptcp_sock *msk = mptcp_sk(sk);
425
426	/* Look for an acknowledged DATA_FIN */
427	if (mptcp_pending_data_fin_ack(sk)) {
428	WRITE_ONCE(msk->snd_data_fin_enable, 0);
429
430	switch (sk->sk_state) {
431	case TCP_FIN_WAIT1:
432	mptcp_set_state(sk, state: TCP_FIN_WAIT2);
433	break;
434	case TCP_CLOSING:
435	case TCP_LAST_ACK:
436	mptcp_set_state(sk, state: TCP_CLOSE);
437	break;
438	}
439
440	mptcp_close_wake_up(sk);
441	}
442	}
443
444	/* can be called with no lock acquired */
445	static bool mptcp_pending_data_fin(struct sock *sk, u64 *seq)
446	{
447	struct mptcp_sock *msk = mptcp_sk(sk);
448
449	if (READ_ONCE(msk->rcv_data_fin) &&
450	((1 << inet_sk_state_load(sk)) &
451	(TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_FIN_WAIT2))) {
452	u64 rcv_data_fin_seq = READ_ONCE(msk->rcv_data_fin_seq);
453
454	if (READ_ONCE(msk->ack_seq) == rcv_data_fin_seq) {
455	if (seq)
456	*seq = rcv_data_fin_seq;
457
458	return true;
459	}
460	}
461
462	return false;
463	}
464
465	static void mptcp_set_datafin_timeout(struct sock *sk)
466	{
467	struct inet_connection_sock *icsk = inet_csk(sk);
468	u32 retransmits;
469
470	retransmits = min_t(u32, icsk->icsk_retransmits,
471	ilog2(TCP_RTO_MAX / TCP_RTO_MIN));
472
473	mptcp_sk(sk)->timer_ival = TCP_RTO_MIN << retransmits;
474	}
475
476	static void __mptcp_set_timeout(struct sock *sk, long tout)
477	{
478	mptcp_sk(sk)->timer_ival = tout > 0 ? tout : TCP_RTO_MIN;
479	}
480
481	static long mptcp_timeout_from_subflow(const struct mptcp_subflow_context *subflow)
482	{
483	const struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
484
485	return inet_csk(sk: ssk)->icsk_pending && !subflow->stale_count ?
486	inet_csk(sk: ssk)->icsk_timeout - jiffies : 0;
487	}
488
489	static void mptcp_set_timeout(struct sock *sk)
490	{
491	struct mptcp_subflow_context *subflow;
492	long tout = 0;
493
494	mptcp_for_each_subflow(mptcp_sk(sk), subflow)
495	tout = max(tout, mptcp_timeout_from_subflow(subflow));
496	__mptcp_set_timeout(sk, tout);
497	}
498
499	static inline bool tcp_can_send_ack(const struct sock *ssk)
500	{
501	return !((1 << inet_sk_state_load(sk: ssk)) &
502	(TCPF_SYN_SENT | TCPF_SYN_RECV | TCPF_TIME_WAIT | TCPF_CLOSE | TCPF_LISTEN));
503	}
504
505	void __mptcp_subflow_send_ack(struct sock *ssk)
506	{
507	if (tcp_can_send_ack(ssk))
508	tcp_send_ack(sk: ssk);
509	}
510
511	static void mptcp_subflow_send_ack(struct sock *ssk)
512	{
513	bool slow;
514
515	slow = lock_sock_fast(sk: ssk);
516	__mptcp_subflow_send_ack(ssk);
517	unlock_sock_fast(sk: ssk, slow);
518	}
519
520	static void mptcp_send_ack(struct mptcp_sock *msk)
521	{
522	struct mptcp_subflow_context *subflow;
523
524	mptcp_for_each_subflow(msk, subflow)
525	mptcp_subflow_send_ack(ssk: mptcp_subflow_tcp_sock(subflow));
526	}
527
528	static void mptcp_subflow_cleanup_rbuf(struct sock *ssk)
529	{
530	bool slow;
531
532	slow = lock_sock_fast(sk: ssk);
533	if (tcp_can_send_ack(ssk))
534	tcp_cleanup_rbuf(sk: ssk, copied: 1);
535	unlock_sock_fast(sk: ssk, slow);
536	}
537
538	static bool mptcp_subflow_could_cleanup(const struct sock *ssk, bool rx_empty)
539	{
540	const struct inet_connection_sock *icsk = inet_csk(sk: ssk);
541	u8 ack_pending = READ_ONCE(icsk->icsk_ack.pending);
542	const struct tcp_sock *tp = tcp_sk(ssk);
543
544	return (ack_pending & ICSK_ACK_SCHED) &&
545	((READ_ONCE(tp->rcv_nxt) - READ_ONCE(tp->rcv_wup) >
546	READ_ONCE(icsk->icsk_ack.rcv_mss)) ||
547	(rx_empty && ack_pending &
548	(ICSK_ACK_PUSHED2 | ICSK_ACK_PUSHED)));
549	}
550
551	static void mptcp_cleanup_rbuf(struct mptcp_sock *msk)
552	{
553	int old_space = READ_ONCE(msk->old_wspace);
554	struct mptcp_subflow_context *subflow;
555	struct sock *sk = (struct sock *)msk;
556	int space = __mptcp_space(sk);
557	bool cleanup, rx_empty;
558
559	cleanup = (space > 0) && (space >= (old_space << 1));
560	rx_empty = !__mptcp_rmem(sk);
561
562	mptcp_for_each_subflow(msk, subflow) {
563	struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
564
565	if (cleanup || mptcp_subflow_could_cleanup(ssk, rx_empty))
566	mptcp_subflow_cleanup_rbuf(ssk);
567	}
568	}
569
570	static bool mptcp_check_data_fin(struct sock *sk)
571	{
572	struct mptcp_sock *msk = mptcp_sk(sk);
573	u64 rcv_data_fin_seq;
574	bool ret = false;
575
576	/* Need to ack a DATA_FIN received from a peer while this side
577	* of the connection is in ESTABLISHED, FIN_WAIT1, or FIN_WAIT2.
578	* msk->rcv_data_fin was set when parsing the incoming options
579	* at the subflow level and the msk lock was not held, so this
580	* is the first opportunity to act on the DATA_FIN and change
581	* the msk state.
582	*
583	* If we are caught up to the sequence number of the incoming
584	* DATA_FIN, send the DATA_ACK now and do state transition. If
585	* not caught up, do nothing and let the recv code send DATA_ACK
586	* when catching up.
587	*/
588
589	if (mptcp_pending_data_fin(sk, seq: &rcv_data_fin_seq)) {
590	WRITE_ONCE(msk->ack_seq, msk->ack_seq + 1);
591	WRITE_ONCE(msk->rcv_data_fin, 0);
592
593	WRITE_ONCE(sk->sk_shutdown, sk->sk_shutdown | RCV_SHUTDOWN);
594	smp_mb__before_atomic(); /* SHUTDOWN must be visible first */
595
596	switch (sk->sk_state) {
597	case TCP_ESTABLISHED:
598	mptcp_set_state(sk, state: TCP_CLOSE_WAIT);
599	break;
600	case TCP_FIN_WAIT1:
601	mptcp_set_state(sk, state: TCP_CLOSING);
602	break;
603	case TCP_FIN_WAIT2:
604	mptcp_set_state(sk, state: TCP_CLOSE);
605	break;
606	default:
607	/* Other states not expected */
608	WARN_ON_ONCE(1);
609	break;
610	}
611
612	ret = true;
613	if (!__mptcp_check_fallback(msk))
614	mptcp_send_ack(msk);
615	mptcp_close_wake_up(sk);
616	}
617	return ret;
618	}
619
620	static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,
621	struct sock *ssk,
622	unsigned int *bytes)
623	{
624	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk: ssk);
625	struct sock *sk = (struct sock *)msk;
626	unsigned int moved = 0;
627	bool more_data_avail;
628	struct tcp_sock *tp;
629	bool done = false;
630	int sk_rbuf;
631
632	sk_rbuf = READ_ONCE(sk->sk_rcvbuf);
633
634	if (!(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
635	int ssk_rbuf = READ_ONCE(ssk->sk_rcvbuf);
636
637	if (unlikely(ssk_rbuf > sk_rbuf)) {
638	WRITE_ONCE(sk->sk_rcvbuf, ssk_rbuf);
639	sk_rbuf = ssk_rbuf;
640	}
641	}
642
643	pr_debug("msk=%p ssk=%p", msk, ssk);
644	tp = tcp_sk(ssk);
645	do {
646	u32 map_remaining, offset;
647	u32 seq = tp->copied_seq;
648	struct sk_buff *skb;
649	bool fin;
650
651	/* try to move as much data as available */
652	map_remaining = subflow->map_data_len -
653	mptcp_subflow_get_map_offset(subflow);
654
655	skb = skb_peek(list_: &ssk->sk_receive_queue);
656	if (!skb) {
657	/* With racing move_skbs_to_msk() and __mptcp_move_skbs(),
658	* a different CPU can have already processed the pending
659	* data, stop here or we can enter an infinite loop
660	*/
661	if (!moved)
662	done = true;
663	break;
664	}
665
666	if (__mptcp_check_fallback(msk)) {
667	/* Under fallback skbs have no MPTCP extension and TCP could
668	* collapse them between the dummy map creation and the
669	* current dequeue. Be sure to adjust the map size.
670	*/
671	map_remaining = skb->len;
672	subflow->map_data_len = skb->len;
673	}
674
675	offset = seq - TCP_SKB_CB(skb)->seq;
676	fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
677	if (fin) {
678	done = true;
679	seq++;
680	}
681
682	if (offset < skb->len) {
683	size_t len = skb->len - offset;
684
685	if (tp->urg_data)
686	done = true;
687
688	if (__mptcp_move_skb(msk, ssk, skb, offset, copy_len: len))
689	moved += len;
690	seq += len;
691
692	if (WARN_ON_ONCE(map_remaining < len))
693	break;
694	} else {
695	WARN_ON_ONCE(!fin);
696	sk_eat_skb(sk: ssk, skb);
697	done = true;
698	}
699
700	WRITE_ONCE(tp->copied_seq, seq);
701	more_data_avail = mptcp_subflow_data_available(sk: ssk);
702
703	if (atomic_read(v: &sk->sk_rmem_alloc) > sk_rbuf) {
704	done = true;
705	break;
706	}
707	} while (more_data_avail);
708
709	*bytes += moved;
710	return done;
711	}
712
713	static bool __mptcp_ofo_queue(struct mptcp_sock *msk)
714	{
715	struct sock *sk = (struct sock *)msk;
716	struct sk_buff *skb, *tail;
717	bool moved = false;
718	struct rb_node *p;
719	u64 end_seq;
720
721	p = rb_first(&msk->out_of_order_queue);
722	pr_debug("msk=%p empty=%d", msk, RB_EMPTY_ROOT(&msk->out_of_order_queue));
723	while (p) {
724	skb = rb_to_skb(p);
725	if (after64(MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq))
726	break;
727
728	p = rb_next(p);
729	rb_erase(&skb->rbnode, &msk->out_of_order_queue);
730
731	if (unlikely(!after64(MPTCP_SKB_CB(skb)->end_seq,
732	msk->ack_seq))) {
733	mptcp_drop(sk, skb);
734	MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_DUPDATA);
735	continue;
736	}
737
738	end_seq = MPTCP_SKB_CB(skb)->end_seq;
739	tail = skb_peek_tail(list_: &sk->sk_receive_queue);
740	if (!tail || !mptcp_ooo_try_coalesce(msk, to: tail, from: skb)) {
741	int delta = msk->ack_seq - MPTCP_SKB_CB(skb)->map_seq;
742
743	/* skip overlapping data, if any */
744	pr_debug("uncoalesced seq=%llx ack seq=%llx delta=%d",
745	MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq,
746	delta);
747	MPTCP_SKB_CB(skb)->offset += delta;
748	MPTCP_SKB_CB(skb)->map_seq += delta;
749	__skb_queue_tail(list: &sk->sk_receive_queue, newsk: skb);
750	}
751	msk->bytes_received += end_seq - msk->ack_seq;
752	WRITE_ONCE(msk->ack_seq, end_seq);
753	moved = true;
754	}
755	return moved;
756	}
757
758	static bool __mptcp_subflow_error_report(struct sock *sk, struct sock *ssk)
759	{
760	int err = sock_error(sk: ssk);
761	int ssk_state;
762
763	if (!err)
764	return false;
765
766	/* only propagate errors on fallen-back sockets or
767	* on MPC connect
768	*/
769	if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(mptcp_sk(sk)))
770	return false;
771
772	/* We need to propagate only transition to CLOSE state.
773	* Orphaned socket will see such state change via
774	* subflow_sched_work_if_closed() and that path will properly
775	* destroy the msk as needed.
776	*/
777	ssk_state = inet_sk_state_load(sk: ssk);
778	if (ssk_state == TCP_CLOSE && !sock_flag(sk, flag: SOCK_DEAD))
779	mptcp_set_state(sk, state: ssk_state);
780	WRITE_ONCE(sk->sk_err, -err);
781
782	/* This barrier is coupled with smp_rmb() in mptcp_poll() */
783	smp_wmb();
784	sk_error_report(sk);
785	return true;
786	}
787
788	void __mptcp_error_report(struct sock *sk)
789	{
790	struct mptcp_subflow_context *subflow;
791	struct mptcp_sock *msk = mptcp_sk(sk);
792
793	mptcp_for_each_subflow(msk, subflow)
794	if (__mptcp_subflow_error_report(sk, ssk: mptcp_subflow_tcp_sock(subflow)))
795	break;
796	}
797
798	/* In most cases we will be able to lock the mptcp socket. If its already
799	* owned, we need to defer to the work queue to avoid ABBA deadlock.
800	*/
801	static bool move_skbs_to_msk(struct mptcp_sock *msk, struct sock *ssk)
802	{
803	struct sock *sk = (struct sock *)msk;
804	unsigned int moved = 0;
805
806	__mptcp_move_skbs_from_subflow(msk, ssk, bytes: &moved);
807	__mptcp_ofo_queue(msk);
808	if (unlikely(ssk->sk_err)) {
809	if (!sock_owned_by_user(sk))
810	__mptcp_error_report(sk);
811	else
812	__set_bit(MPTCP_ERROR_REPORT, &msk->cb_flags);
813	}
814
815	/* If the moves have caught up with the DATA_FIN sequence number
816	* it's time to ack the DATA_FIN and change socket state, but
817	* this is not a good place to change state. Let the workqueue
818	* do it.
819	*/
820	if (mptcp_pending_data_fin(sk, NULL))
821	mptcp_schedule_work(sk);
822	return moved > 0;
823	}
824
825	void mptcp_data_ready(struct sock *sk, struct sock *ssk)
826	{
827	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk: ssk);
828	struct mptcp_sock *msk = mptcp_sk(sk);
829	int sk_rbuf, ssk_rbuf;
830
831	/* The peer can send data while we are shutting down this
832	* subflow at msk destruction time, but we must avoid enqueuing
833	* more data to the msk receive queue
834	*/
835	if (unlikely(subflow->disposable))
836	return;
837
838	ssk_rbuf = READ_ONCE(ssk->sk_rcvbuf);
839	sk_rbuf = READ_ONCE(sk->sk_rcvbuf);
840	if (unlikely(ssk_rbuf > sk_rbuf))
841	sk_rbuf = ssk_rbuf;
842
843	/* over limit? can't append more skbs to msk, Also, no need to wake-up*/
844	if (__mptcp_rmem(sk) > sk_rbuf) {
845	MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_RCVPRUNED);
846	return;
847	}
848
849	/* Wake-up the reader only for in-sequence data */
850	mptcp_data_lock(sk);
851	if (move_skbs_to_msk(msk, ssk) && mptcp_epollin_ready(sk))
852	sk->sk_data_ready(sk);
853	mptcp_data_unlock(sk);
854	}
855
856	static void mptcp_subflow_joined(struct mptcp_sock *msk, struct sock *ssk)
857	{
858	mptcp_subflow_ctx(sk: ssk)->map_seq = READ_ONCE(msk->ack_seq);
859	WRITE_ONCE(msk->allow_infinite_fallback, false);
860	mptcp_event(type: MPTCP_EVENT_SUB_ESTABLISHED, msk, ssk, GFP_ATOMIC);
861	}
862
863	static bool __mptcp_finish_join(struct mptcp_sock *msk, struct sock *ssk)
864	{
865	struct sock *sk = (struct sock *)msk;
866
867	if (sk->sk_state != TCP_ESTABLISHED)
868	return false;
869
870	/* attach to msk socket only after we are sure we will deal with it
871	* at close time
872	*/
873	if (sk->sk_socket && !ssk->sk_socket)
874	mptcp_sock_graft(sk: ssk, parent: sk->sk_socket);
875
876	mptcp_subflow_ctx(sk: ssk)->subflow_id = msk->subflow_id++;
877	mptcp_sockopt_sync_locked(msk, ssk);
878	mptcp_subflow_joined(msk, ssk);
879	mptcp_stop_tout_timer(sk);
880	__mptcp_propagate_sndbuf(sk, ssk);
881	return true;
882	}
883
884	static void __mptcp_flush_join_list(struct sock *sk, struct list_head *join_list)
885	{
886	struct mptcp_subflow_context *tmp, *subflow;
887	struct mptcp_sock *msk = mptcp_sk(sk);
888
889	list_for_each_entry_safe(subflow, tmp, join_list, node) {
890	struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
891	bool slow = lock_sock_fast(sk: ssk);
892
893	list_move_tail(list: &subflow->node, head: &msk->conn_list);
894	if (!__mptcp_finish_join(msk, ssk))
895	mptcp_subflow_reset(ssk);
896	unlock_sock_fast(sk: ssk, slow);
897	}
898	}
899
900	static bool mptcp_rtx_timer_pending(struct sock *sk)
901	{
902	return timer_pending(timer: &inet_csk(sk)->icsk_retransmit_timer);
903	}
904
905	static void mptcp_reset_rtx_timer(struct sock *sk)
906	{
907	struct inet_connection_sock *icsk = inet_csk(sk);
908	unsigned long tout;
909
910	/* prevent rescheduling on close */
911	if (unlikely(inet_sk_state_load(sk) == TCP_CLOSE))
912	return;
913
914	tout = mptcp_sk(sk)->timer_ival;
915	sk_reset_timer(sk, timer: &icsk->icsk_retransmit_timer, expires: jiffies + tout);
916	}
917
918	bool mptcp_schedule_work(struct sock *sk)
919	{
920	if (inet_sk_state_load(sk) != TCP_CLOSE &&
921	schedule_work(work: &mptcp_sk(sk)->work)) {
922	/* each subflow already holds a reference to the sk, and the
923	* workqueue is invoked by a subflow, so sk can't go away here.
924	*/
925	sock_hold(sk);
926	return true;
927	}
928	return false;
929	}
930
931	static struct sock *mptcp_subflow_recv_lookup(const struct mptcp_sock *msk)
932	{
933	struct mptcp_subflow_context *subflow;
934
935	msk_owned_by_me(msk);
936
937	mptcp_for_each_subflow(msk, subflow) {
938	if (READ_ONCE(subflow->data_avail))
939	return mptcp_subflow_tcp_sock(subflow);
940	}
941
942	return NULL;
943	}
944
945	static bool mptcp_skb_can_collapse_to(u64 write_seq,
946	const struct sk_buff *skb,
947	const struct mptcp_ext *mpext)
948	{
949	if (!tcp_skb_can_collapse_to(skb))
950	return false;
951
952	/* can collapse only if MPTCP level sequence is in order and this
953	* mapping has not been xmitted yet
954	*/
955	return mpext && mpext->data_seq + mpext->data_len == write_seq &&
956	!mpext->frozen;
957	}
958
959	/* we can append data to the given data frag if:
960	* - there is space available in the backing page_frag
961	* - the data frag tail matches the current page_frag free offset
962	* - the data frag end sequence number matches the current write seq
963	*/
964	static bool mptcp_frag_can_collapse_to(const struct mptcp_sock *msk,
965	const struct page_frag *pfrag,
966	const struct mptcp_data_frag *df)
967	{
968	return df && pfrag->page == df->page &&
969	pfrag->size - pfrag->offset > 0 &&
970	pfrag->offset == (df->offset + df->data_len) &&
971	df->data_seq + df->data_len == msk->write_seq;
972	}
973
974	static void dfrag_uncharge(struct sock *sk, int len)
975	{
976	sk_mem_uncharge(sk, size: len);
977	sk_wmem_queued_add(sk, val: -len);
978	}
979
980	static void dfrag_clear(struct sock *sk, struct mptcp_data_frag *dfrag)
981	{
982	int len = dfrag->data_len + dfrag->overhead;
983
984	list_del(entry: &dfrag->list);
985	dfrag_uncharge(sk, len);
986	put_page(page: dfrag->page);
987	}
988
989	/* called under both the msk socket lock and the data lock */
990	static void __mptcp_clean_una(struct sock *sk)
991	{
992	struct mptcp_sock *msk = mptcp_sk(sk);
993	struct mptcp_data_frag *dtmp, *dfrag;
994	u64 snd_una;
995
996	snd_una = msk->snd_una;
997	list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list) {
998	if (after64(dfrag->data_seq + dfrag->data_len, snd_una))
999	break;
1000
1001	if (unlikely(dfrag == msk->first_pending)) {
1002	/* in recovery mode can see ack after the current snd head */
1003	if (WARN_ON_ONCE(!msk->recovery))
1004	break;
1005
1006	WRITE_ONCE(msk->first_pending, mptcp_send_next(sk));
1007	}
1008
1009	dfrag_clear(sk, dfrag);
1010	}
1011
1012	dfrag = mptcp_rtx_head(sk);
1013	if (dfrag && after64(snd_una, dfrag->data_seq)) {
1014	u64 delta = snd_una - dfrag->data_seq;
1015
1016	/* prevent wrap around in recovery mode */
1017	if (unlikely(delta > dfrag->already_sent)) {
1018	if (WARN_ON_ONCE(!msk->recovery))
1019	goto out;
1020	if (WARN_ON_ONCE(delta > dfrag->data_len))
1021	goto out;
1022	dfrag->already_sent += delta - dfrag->already_sent;
1023	}
1024
1025	dfrag->data_seq += delta;
1026	dfrag->offset += delta;
1027	dfrag->data_len -= delta;
1028	dfrag->already_sent -= delta;
1029
1030	dfrag_uncharge(sk, len: delta);
1031	}
1032
1033	/* all retransmitted data acked, recovery completed */
1034	if (unlikely(msk->recovery) && after64(msk->snd_una, msk->recovery_snd_nxt))
1035	msk->recovery = false;
1036
1037	out:
1038	if (snd_una == msk->snd_nxt && snd_una == msk->write_seq) {
1039	if (mptcp_rtx_timer_pending(sk) && !mptcp_data_fin_enabled(msk))
1040	mptcp_stop_rtx_timer(sk);
1041	} else {
1042	mptcp_reset_rtx_timer(sk);
1043	}
1044
1045	if (mptcp_pending_data_fin_ack(sk))
1046	mptcp_schedule_work(sk);
1047	}
1048
1049	static void __mptcp_clean_una_wakeup(struct sock *sk)
1050	{
1051	lockdep_assert_held_once(&sk->sk_lock.slock);
1052
1053	__mptcp_clean_una(sk);
1054	mptcp_write_space(sk);
1055	}
1056
1057	static void mptcp_clean_una_wakeup(struct sock *sk)
1058	{
1059	mptcp_data_lock(sk);
1060	__mptcp_clean_una_wakeup(sk);
1061	mptcp_data_unlock(sk);
1062	}
1063
1064	static void mptcp_enter_memory_pressure(struct sock *sk)
1065	{
1066	struct mptcp_subflow_context *subflow;
1067	struct mptcp_sock *msk = mptcp_sk(sk);
1068	bool first = true;
1069
1070	mptcp_for_each_subflow(msk, subflow) {
1071	struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
1072
1073	if (first)
1074	tcp_enter_memory_pressure(sk: ssk);
1075	sk_stream_moderate_sndbuf(sk: ssk);
1076
1077	first = false;
1078	}
1079	__mptcp_sync_sndbuf(sk);
1080	}
1081
1082	/* ensure we get enough memory for the frag hdr, beyond some minimal amount of
1083	* data
1084	*/
1085	static bool mptcp_page_frag_refill(struct sock *sk, struct page_frag *pfrag)
1086	{
1087	if (likely(skb_page_frag_refill(32U + sizeof(struct mptcp_data_frag),
1088	pfrag, sk->sk_allocation)))
1089	return true;
1090
1091	mptcp_enter_memory_pressure(sk);
1092	return false;
1093	}
1094
1095	static struct mptcp_data_frag *
1096	mptcp_carve_data_frag(const struct mptcp_sock *msk, struct page_frag *pfrag,
1097	int orig_offset)
1098	{
1099	int offset = ALIGN(orig_offset, sizeof(long));
1100	struct mptcp_data_frag *dfrag;
1101
1102	dfrag = (struct mptcp_data_frag *)(page_to_virt(pfrag->page) + offset);
1103	dfrag->data_len = 0;
1104	dfrag->data_seq = msk->write_seq;
1105	dfrag->overhead = offset - orig_offset + sizeof(struct mptcp_data_frag);
1106	dfrag->offset = offset + sizeof(struct mptcp_data_frag);
1107	dfrag->already_sent = 0;
1108	dfrag->page = pfrag->page;
1109
1110	return dfrag;
1111	}
1112
1113	struct mptcp_sendmsg_info {
1114	int mss_now;
1115	int size_goal;
1116	u16 limit;
1117	u16 sent;
1118	unsigned int flags;
1119	bool data_lock_held;
1120	};
1121
1122	static int mptcp_check_allowed_size(const struct mptcp_sock *msk, struct sock *ssk,
1123	u64 data_seq, int avail_size)
1124	{
1125	u64 window_end = mptcp_wnd_end(msk);
1126	u64 mptcp_snd_wnd;
1127
1128	if (__mptcp_check_fallback(msk))
1129	return avail_size;
1130
1131	mptcp_snd_wnd = window_end - data_seq;
1132	avail_size = min_t(unsigned int, mptcp_snd_wnd, avail_size);
1133
1134	if (unlikely(tcp_sk(ssk)->snd_wnd < mptcp_snd_wnd)) {
1135	tcp_sk(ssk)->snd_wnd = min_t(u64, U32_MAX, mptcp_snd_wnd);
1136	MPTCP_INC_STATS(net: sock_net(sk: ssk), field: MPTCP_MIB_SNDWNDSHARED);
1137	}
1138
1139	return avail_size;
1140	}
1141
1142	static bool __mptcp_add_ext(struct sk_buff *skb, gfp_t gfp)
1143	{
1144	struct skb_ext *mpext = __skb_ext_alloc(flags: gfp);
1145
1146	if (!mpext)
1147	return false;
1148	__skb_ext_set(skb, id: SKB_EXT_MPTCP, ext: mpext);
1149	return true;
1150	}
1151
1152	static struct sk_buff *__mptcp_do_alloc_tx_skb(struct sock *sk, gfp_t gfp)
1153	{
1154	struct sk_buff *skb;
1155
1156	skb = alloc_skb_fclone(MAX_TCP_HEADER, priority: gfp);
1157	if (likely(skb)) {
1158	if (likely(__mptcp_add_ext(skb, gfp))) {
1159	skb_reserve(skb, MAX_TCP_HEADER);
1160	skb->ip_summed = CHECKSUM_PARTIAL;
1161	INIT_LIST_HEAD(list: &skb->tcp_tsorted_anchor);
1162	return skb;
1163	}
1164	__kfree_skb(skb);
1165	} else {
1166	mptcp_enter_memory_pressure(sk);
1167	}
1168	return NULL;
1169	}
1170
1171	static struct sk_buff *__mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, gfp_t gfp)
1172	{
1173	struct sk_buff *skb;
1174
1175	skb = __mptcp_do_alloc_tx_skb(sk, gfp);
1176	if (!skb)
1177	return NULL;
1178
1179	if (likely(sk_wmem_schedule(ssk, skb->truesize))) {
1180	tcp_skb_entail(sk: ssk, skb);
1181	return skb;
1182	}
1183	tcp_skb_tsorted_anchor_cleanup(skb);
1184	kfree_skb(skb);
1185	return NULL;
1186	}
1187
1188	static struct sk_buff *mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, bool data_lock_held)
1189	{
1190	gfp_t gfp = data_lock_held ? GFP_ATOMIC : sk->sk_allocation;
1191
1192	return __mptcp_alloc_tx_skb(sk, ssk, gfp);
1193	}
1194
1195	/* note: this always recompute the csum on the whole skb, even
1196	* if we just appended a single frag. More status info needed
1197	*/
1198	static void mptcp_update_data_checksum(struct sk_buff *skb, int added)
1199	{
1200	struct mptcp_ext *mpext = mptcp_get_ext(skb);
1201	__wsum csum = ~csum_unfold(n: mpext->csum);
1202	int offset = skb->len - added;
1203
1204	mpext->csum = csum_fold(sum: csum_block_add(csum, csum2: skb_checksum(skb, offset, len: added, csum: 0), offset));
1205	}
1206
1207	static void mptcp_update_infinite_map(struct mptcp_sock *msk,
1208	struct sock *ssk,
1209	struct mptcp_ext *mpext)
1210	{
1211	if (!mpext)
1212	return;
1213
1214	mpext->infinite_map = 1;
1215	mpext->data_len = 0;
1216
1217	MPTCP_INC_STATS(net: sock_net(sk: ssk), field: MPTCP_MIB_INFINITEMAPTX);
1218	mptcp_subflow_ctx(sk: ssk)->send_infinite_map = 0;
1219	pr_fallback(msk);
1220	mptcp_do_fallback(ssk);
1221	}
1222
1223	#define MPTCP_MAX_GSO_SIZE (GSO_LEGACY_MAX_SIZE - (MAX_TCP_HEADER + 1))
1224
1225	static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
1226	struct mptcp_data_frag *dfrag,
1227	struct mptcp_sendmsg_info *info)
1228	{
1229	u64 data_seq = dfrag->data_seq + info->sent;
1230	int offset = dfrag->offset + info->sent;
1231	struct mptcp_sock *msk = mptcp_sk(sk);
1232	bool zero_window_probe = false;
1233	struct mptcp_ext *mpext = NULL;
1234	bool can_coalesce = false;
1235	bool reuse_skb = true;
1236	struct sk_buff *skb;
1237	size_t copy;
1238	int i;
1239
1240	pr_debug("msk=%p ssk=%p sending dfrag at seq=%llu len=%u already sent=%u",
1241	msk, ssk, dfrag->data_seq, dfrag->data_len, info->sent);
1242
1243	if (WARN_ON_ONCE(info->sent > info->limit ||
1244	info->limit > dfrag->data_len))
1245	return 0;
1246
1247	if (unlikely(!__tcp_can_send(ssk)))
1248	return -EAGAIN;
1249
1250	/* compute send limit */
1251	if (unlikely(ssk->sk_gso_max_size > MPTCP_MAX_GSO_SIZE))
1252	ssk->sk_gso_max_size = MPTCP_MAX_GSO_SIZE;
1253	info->mss_now = tcp_send_mss(sk: ssk, size_goal: &info->size_goal, flags: info->flags);
1254	copy = info->size_goal;
1255
1256	skb = tcp_write_queue_tail(sk: ssk);
1257	if (skb && copy > skb->len) {
1258	/* Limit the write to the size available in the
1259	* current skb, if any, so that we create at most a new skb.
1260	* Explicitly tells TCP internals to avoid collapsing on later
1261	* queue management operation, to avoid breaking the ext <->
1262	* SSN association set here
1263	*/
1264	mpext = mptcp_get_ext(skb);
1265	if (!mptcp_skb_can_collapse_to(write_seq: data_seq, skb, mpext)) {
1266	TCP_SKB_CB(skb)->eor = 1;
1267	tcp_mark_push(tcp_sk(ssk), skb);
1268	goto alloc_skb;
1269	}
1270
1271	i = skb_shinfo(skb)->nr_frags;
1272	can_coalesce = skb_can_coalesce(skb, i, page: dfrag->page, off: offset);
1273	if (!can_coalesce && i >= READ_ONCE(sysctl_max_skb_frags)) {
1274	tcp_mark_push(tcp_sk(ssk), skb);
1275	goto alloc_skb;
1276	}
1277
1278	copy -= skb->len;
1279	} else {
1280	alloc_skb:
1281	skb = mptcp_alloc_tx_skb(sk, ssk, data_lock_held: info->data_lock_held);
1282	if (!skb)
1283	return -ENOMEM;
1284
1285	i = skb_shinfo(skb)->nr_frags;
1286	reuse_skb = false;
1287	mpext = mptcp_get_ext(skb);
1288	}
1289
1290	/* Zero window and all data acked? Probe. */
1291	copy = mptcp_check_allowed_size(msk, ssk, data_seq, avail_size: copy);
1292	if (copy == 0) {
1293	u64 snd_una = READ_ONCE(msk->snd_una);
1294
1295	if (snd_una != msk->snd_nxt || tcp_write_queue_tail(sk: ssk)) {
1296	tcp_remove_empty_skb(sk: ssk);
1297	return 0;
1298	}
1299
1300	zero_window_probe = true;
1301	data_seq = snd_una - 1;
1302	copy = 1;
1303	}
1304
1305	copy = min_t(size_t, copy, info->limit - info->sent);
1306	if (!sk_wmem_schedule(sk: ssk, size: copy)) {
1307	tcp_remove_empty_skb(sk: ssk);
1308	return -ENOMEM;
1309	}
1310
1311	if (can_coalesce) {
1312	skb_frag_size_add(frag: &skb_shinfo(skb)->frags[i - 1], delta: copy);
1313	} else {
1314	get_page(page: dfrag->page);
1315	skb_fill_page_desc(skb, i, page: dfrag->page, off: offset, size: copy);
1316	}
1317
1318	skb->len += copy;
1319	skb->data_len += copy;
1320	skb->truesize += copy;
1321	sk_wmem_queued_add(sk: ssk, val: copy);
1322	sk_mem_charge(sk: ssk, size: copy);
1323	WRITE_ONCE(tcp_sk(ssk)->write_seq, tcp_sk(ssk)->write_seq + copy);
1324	TCP_SKB_CB(skb)->end_seq += copy;
1325	tcp_skb_pcount_set(skb, segs: 0);
1326
1327	/* on skb reuse we just need to update the DSS len */
1328	if (reuse_skb) {
1329	TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
1330	mpext->data_len += copy;
1331	goto out;
1332	}
1333
1334	memset(mpext, 0, sizeof(*mpext));
1335	mpext->data_seq = data_seq;
1336	mpext->subflow_seq = mptcp_subflow_ctx(sk: ssk)->rel_write_seq;
1337	mpext->data_len = copy;
1338	mpext->use_map = 1;
1339	mpext->dsn64 = 1;
1340
1341	pr_debug("data_seq=%llu subflow_seq=%u data_len=%u dsn64=%d",
1342	mpext->data_seq, mpext->subflow_seq, mpext->data_len,
1343	mpext->dsn64);
1344
1345	if (zero_window_probe) {
1346	mptcp_subflow_ctx(sk: ssk)->rel_write_seq += copy;
1347	mpext->frozen = 1;
1348	if (READ_ONCE(msk->csum_enabled))
1349	mptcp_update_data_checksum(skb, added: copy);
1350	tcp_push_pending_frames(sk: ssk);
1351	return 0;
1352	}
1353	out:
1354	if (READ_ONCE(msk->csum_enabled))
1355	mptcp_update_data_checksum(skb, added: copy);
1356	if (mptcp_subflow_ctx(sk: ssk)->send_infinite_map)
1357	mptcp_update_infinite_map(msk, ssk, mpext);
1358	trace_mptcp_sendmsg_frag(mpext);
1359	mptcp_subflow_ctx(sk: ssk)->rel_write_seq += copy;
1360	return copy;
1361	}
1362
1363	#define MPTCP_SEND_BURST_SIZE ((1 << 16) - \
1364	sizeof(struct tcphdr) - \
1365	MAX_TCP_OPTION_SPACE - \
1366	sizeof(struct ipv6hdr) - \
1367	sizeof(struct frag_hdr))
1368
1369	struct subflow_send_info {
1370	struct sock *ssk;
1371	u64 linger_time;
1372	};
1373
1374	void mptcp_subflow_set_active(struct mptcp_subflow_context *subflow)
1375	{
1376	if (!subflow->stale)
1377	return;
1378
1379	subflow->stale = 0;
1380	MPTCP_INC_STATS(net: sock_net(sk: mptcp_subflow_tcp_sock(subflow)), field: MPTCP_MIB_SUBFLOWRECOVER);
1381	}
1382
1383	bool mptcp_subflow_active(struct mptcp_subflow_context *subflow)
1384	{
1385	if (unlikely(subflow->stale)) {
1386	u32 rcv_tstamp = READ_ONCE(tcp_sk(mptcp_subflow_tcp_sock(subflow))->rcv_tstamp);
1387
1388	if (subflow->stale_rcv_tstamp == rcv_tstamp)
1389	return false;
1390
1391	mptcp_subflow_set_active(subflow);
1392	}
1393	return __mptcp_subflow_active(subflow);
1394	}
1395
1396	#define SSK_MODE_ACTIVE 0
1397	#define SSK_MODE_BACKUP 1
1398	#define SSK_MODE_MAX 2
1399
1400	/* implement the mptcp packet scheduler;
1401	* returns the subflow that will transmit the next DSS
1402	* additionally updates the rtx timeout
1403	*/
1404	struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
1405	{
1406	struct subflow_send_info send_info[SSK_MODE_MAX];
1407	struct mptcp_subflow_context *subflow;
1408	struct sock *sk = (struct sock *)msk;
1409	u32 pace, burst, wmem;
1410	int i, nr_active = 0;
1411	struct sock *ssk;
1412	u64 linger_time;
1413	long tout = 0;
1414
1415	/* pick the subflow with the lower wmem/wspace ratio */
1416	for (i = 0; i < SSK_MODE_MAX; ++i) {
1417	send_info[i].ssk = NULL;
1418	send_info[i].linger_time = -1;
1419	}
1420
1421	mptcp_for_each_subflow(msk, subflow) {
1422	trace_mptcp_subflow_get_send(subflow);
1423	ssk = mptcp_subflow_tcp_sock(subflow);
1424	if (!mptcp_subflow_active(subflow))
1425	continue;
1426
1427	tout = max(tout, mptcp_timeout_from_subflow(subflow));
1428	nr_active += !subflow->backup;
1429	pace = subflow->avg_pacing_rate;
1430	if (unlikely(!pace)) {
1431	/* init pacing rate from socket */
1432	subflow->avg_pacing_rate = READ_ONCE(ssk->sk_pacing_rate);
1433	pace = subflow->avg_pacing_rate;
1434	if (!pace)
1435	continue;
1436	}
1437
1438	linger_time = div_u64(dividend: (u64)READ_ONCE(ssk->sk_wmem_queued) << 32, divisor: pace);
1439	if (linger_time < send_info[subflow->backup].linger_time) {
1440	send_info[subflow->backup].ssk = ssk;
1441	send_info[subflow->backup].linger_time = linger_time;
1442	}
1443	}
1444	__mptcp_set_timeout(sk, tout);
1445
1446	/* pick the best backup if no other subflow is active */
1447	if (!nr_active)
1448	send_info[SSK_MODE_ACTIVE].ssk = send_info[SSK_MODE_BACKUP].ssk;
1449
1450	/* According to the blest algorithm, to avoid HoL blocking for the
1451	* faster flow, we need to:
1452	* - estimate the faster flow linger time
1453	* - use the above to estimate the amount of byte transferred
1454	* by the faster flow
1455	* - check that the amount of queued data is greter than the above,
1456	* otherwise do not use the picked, slower, subflow
1457	* We select the subflow with the shorter estimated time to flush
1458	* the queued mem, which basically ensure the above. We just need
1459	* to check that subflow has a non empty cwin.
1460	*/
1461	ssk = send_info[SSK_MODE_ACTIVE].ssk;
1462	if (!ssk || !sk_stream_memory_free(sk: ssk))
1463	return NULL;
1464
1465	burst = min_t(int, MPTCP_SEND_BURST_SIZE, mptcp_wnd_end(msk) - msk->snd_nxt);
1466	wmem = READ_ONCE(ssk->sk_wmem_queued);
1467	if (!burst)
1468	return ssk;
1469
1470	subflow = mptcp_subflow_ctx(sk: ssk);
1471	subflow->avg_pacing_rate = div_u64(dividend: (u64)subflow->avg_pacing_rate * wmem +
1472	READ_ONCE(ssk->sk_pacing_rate) * burst,
1473	divisor: burst + wmem);
1474	msk->snd_burst = burst;
1475	return ssk;
1476	}
1477
1478	static void mptcp_push_release(struct sock *ssk, struct mptcp_sendmsg_info *info)
1479	{
1480	tcp_push(sk: ssk, flags: 0, mss_now: info->mss_now, tcp_sk(ssk)->nonagle, size_goal: info->size_goal);
1481	release_sock(sk: ssk);
1482	}
1483
1484	static void mptcp_update_post_push(struct mptcp_sock *msk,
1485	struct mptcp_data_frag *dfrag,
1486	u32 sent)
1487	{
1488	u64 snd_nxt_new = dfrag->data_seq;
1489
1490	dfrag->already_sent += sent;
1491
1492	msk->snd_burst -= sent;
1493
1494	snd_nxt_new += dfrag->already_sent;
1495
1496	/* snd_nxt_new can be smaller than snd_nxt in case mptcp
1497	* is recovering after a failover. In that event, this re-sends
1498	* old segments.
1499	*
1500	* Thus compute snd_nxt_new candidate based on
1501	* the dfrag->data_seq that was sent and the data
1502	* that has been handed to the subflow for transmission
1503	* and skip update in case it was old dfrag.
1504	*/
1505	if (likely(after64(snd_nxt_new, msk->snd_nxt))) {
1506	msk->bytes_sent += snd_nxt_new - msk->snd_nxt;
1507	WRITE_ONCE(msk->snd_nxt, snd_nxt_new);
1508	}
1509	}
1510
1511	void mptcp_check_and_set_pending(struct sock *sk)
1512	{
1513	if (mptcp_send_head(sk)) {
1514	mptcp_data_lock(sk);
1515	mptcp_sk(sk)->cb_flags |= BIT(MPTCP_PUSH_PENDING);
1516	mptcp_data_unlock(sk);
1517	}
1518	}
1519
1520	static int __subflow_push_pending(struct sock *sk, struct sock *ssk,
1521	struct mptcp_sendmsg_info *info)
1522	{
1523	struct mptcp_sock *msk = mptcp_sk(sk);
1524	struct mptcp_data_frag *dfrag;
1525	int len, copied = 0, err = 0;
1526
1527	while ((dfrag = mptcp_send_head(sk))) {
1528	info->sent = dfrag->already_sent;
1529	info->limit = dfrag->data_len;
1530	len = dfrag->data_len - dfrag->already_sent;
1531	while (len > 0) {
1532	int ret = 0;
1533
1534	ret = mptcp_sendmsg_frag(sk, ssk, dfrag, info);
1535	if (ret <= 0) {
1536	err = copied ? : ret;
1537	goto out;
1538	}
1539
1540	info->sent += ret;
1541	copied += ret;
1542	len -= ret;
1543
1544	mptcp_update_post_push(msk, dfrag, sent: ret);
1545	}
1546	WRITE_ONCE(msk->first_pending, mptcp_send_next(sk));
1547
1548	if (msk->snd_burst <= 0 ||
1549	!sk_stream_memory_free(sk: ssk) ||
1550	!mptcp_subflow_active(subflow: mptcp_subflow_ctx(sk: ssk))) {
1551	err = copied;
1552	goto out;
1553	}
1554	mptcp_set_timeout(sk);
1555	}
1556	err = copied;
1557
1558	out:
1559	return err;
1560	}
1561
1562	void __mptcp_push_pending(struct sock *sk, unsigned int flags)
1563	{
1564	struct sock *prev_ssk = NULL, *ssk = NULL;
1565	struct mptcp_sock *msk = mptcp_sk(sk);
1566	struct mptcp_sendmsg_info info = {
1567	.flags = flags,
1568	};
1569	bool do_check_data_fin = false;
1570	int push_count = 1;
1571
1572	while (mptcp_send_head(sk) && (push_count > 0)) {
1573	struct mptcp_subflow_context *subflow;
1574	int ret = 0;
1575
1576	if (mptcp_sched_get_send(msk))
1577	break;
1578
1579	push_count = 0;
1580
1581	mptcp_for_each_subflow(msk, subflow) {
1582	if (READ_ONCE(subflow->scheduled)) {
1583	mptcp_subflow_set_scheduled(subflow, scheduled: false);
1584
1585	prev_ssk = ssk;
1586	ssk = mptcp_subflow_tcp_sock(subflow);
1587	if (ssk != prev_ssk) {
1588	/* First check. If the ssk has changed since
1589	* the last round, release prev_ssk
1590	*/
1591	if (prev_ssk)
1592	mptcp_push_release(ssk: prev_ssk, info: &info);
1593
1594	/* Need to lock the new subflow only if different
1595	* from the previous one, otherwise we are still
1596	* helding the relevant lock
1597	*/
1598	lock_sock(sk: ssk);
1599	}
1600
1601	push_count++;
1602
1603	ret = __subflow_push_pending(sk, ssk, info: &info);
1604	if (ret <= 0) {
1605	if (ret != -EAGAIN ||
1606	(1 << ssk->sk_state) &
1607	(TCPF_FIN_WAIT1 | TCPF_FIN_WAIT2 | TCPF_CLOSE))
1608	push_count--;
1609	continue;
1610	}
1611	do_check_data_fin = true;
1612	}
1613	}
1614	}
1615
1616	/* at this point we held the socket lock for the last subflow we used */
1617	if (ssk)
1618	mptcp_push_release(ssk, info: &info);
1619
1620	/* ensure the rtx timer is running */
1621	if (!mptcp_rtx_timer_pending(sk))
1622	mptcp_reset_rtx_timer(sk);
1623	if (do_check_data_fin)
1624	mptcp_check_send_data_fin(sk);
1625	}
1626
1627	static void __mptcp_subflow_push_pending(struct sock *sk, struct sock *ssk, bool first)
1628	{
1629	struct mptcp_sock *msk = mptcp_sk(sk);
1630	struct mptcp_sendmsg_info info = {
1631	.data_lock_held = true,
1632	};
1633	bool keep_pushing = true;
1634	struct sock *xmit_ssk;
1635	int copied = 0;
1636
1637	info.flags = 0;
1638	while (mptcp_send_head(sk) && keep_pushing) {
1639	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk: ssk);
1640	int ret = 0;
1641
1642	/* check for a different subflow usage only after
1643	* spooling the first chunk of data
1644	*/
1645	if (first) {
1646	mptcp_subflow_set_scheduled(subflow, scheduled: false);
1647	ret = __subflow_push_pending(sk, ssk, info: &info);
1648	first = false;
1649	if (ret <= 0)
1650	break;
1651	copied += ret;
1652	continue;
1653	}
1654
1655	if (mptcp_sched_get_send(msk))
1656	goto out;
1657
1658	if (READ_ONCE(subflow->scheduled)) {
1659	mptcp_subflow_set_scheduled(subflow, scheduled: false);
1660	ret = __subflow_push_pending(sk, ssk, info: &info);
1661	if (ret <= 0)
1662	keep_pushing = false;
1663	copied += ret;
1664	}
1665
1666	mptcp_for_each_subflow(msk, subflow) {
1667	if (READ_ONCE(subflow->scheduled)) {
1668	xmit_ssk = mptcp_subflow_tcp_sock(subflow);
1669	if (xmit_ssk != ssk) {
1670	mptcp_subflow_delegate(subflow,
1671	MPTCP_DELEGATE_SEND);
1672	keep_pushing = false;
1673	}
1674	}
1675	}
1676	}
1677
1678	out:
1679	/* __mptcp_alloc_tx_skb could have released some wmem and we are
1680	* not going to flush it via release_sock()
1681	*/
1682	if (copied) {
1683	tcp_push(sk: ssk, flags: 0, mss_now: info.mss_now, tcp_sk(ssk)->nonagle,
1684	size_goal: info.size_goal);
1685	if (!mptcp_rtx_timer_pending(sk))
1686	mptcp_reset_rtx_timer(sk);
1687
1688	if (msk->snd_data_fin_enable &&
1689	msk->snd_nxt + 1 == msk->write_seq)
1690	mptcp_schedule_work(sk);
1691	}
1692	}
1693
1694	static int mptcp_disconnect(struct sock *sk, int flags);
1695
1696	static int mptcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg,
1697	size_t len, int *copied_syn)
1698	{
1699	unsigned int saved_flags = msg->msg_flags;
1700	struct mptcp_sock *msk = mptcp_sk(sk);
1701	struct sock *ssk;
1702	int ret;
1703
1704	/* on flags based fastopen the mptcp is supposed to create the
1705	* first subflow right now. Otherwise we are in the defer_connect
1706	* path, and the first subflow must be already present.
1707	* Since the defer_connect flag is cleared after the first succsful
1708	* fastopen attempt, no need to check for additional subflow status.
1709	*/
1710	if (msg->msg_flags & MSG_FASTOPEN) {
1711	ssk = __mptcp_nmpc_sk(msk);
1712	if (IS_ERR(ptr: ssk))
1713	return PTR_ERR(ptr: ssk);
1714	}
1715	if (!msk->first)
1716	return -EINVAL;
1717
1718	ssk = msk->first;
1719
1720	lock_sock(sk: ssk);
1721	msg->msg_flags |= MSG_DONTWAIT;
1722	msk->fastopening = 1;
1723	ret = tcp_sendmsg_fastopen(sk: ssk, msg, copied: copied_syn, size: len, NULL);
1724	msk->fastopening = 0;
1725	msg->msg_flags = saved_flags;
1726	release_sock(sk: ssk);
1727
1728	/* do the blocking bits of inet_stream_connect outside the ssk socket lock */
1729	if (ret == -EINPROGRESS && !(msg->msg_flags & MSG_DONTWAIT)) {
1730	ret = __inet_stream_connect(sock: sk->sk_socket, uaddr: msg->msg_name,
1731	addr_len: msg->msg_namelen, flags: msg->msg_flags, is_sendmsg: 1);
1732
1733	/* Keep the same behaviour of plain TCP: zero the copied bytes in
1734	* case of any error, except timeout or signal
1735	*/
1736	if (ret && ret != -EINPROGRESS && ret != -ERESTARTSYS && ret != -EINTR)
1737	*copied_syn = 0;
1738	} else if (ret && ret != -EINPROGRESS) {
1739	/* The disconnect() op called by tcp_sendmsg_fastopen()/
1740	* __inet_stream_connect() can fail, due to looking check,
1741	* see mptcp_disconnect().
1742	* Attempt it again outside the problematic scope.
1743	*/
1744	if (!mptcp_disconnect(sk, flags: 0))
1745	sk->sk_socket->state = SS_UNCONNECTED;
1746	}
1747	inet_clear_bit(DEFER_CONNECT, sk);
1748
1749	return ret;
1750	}
1751
1752	static int do_copy_data_nocache(struct sock *sk, int copy,
1753	struct iov_iter *from, char *to)
1754	{
1755	if (sk->sk_route_caps & NETIF_F_NOCACHE_COPY) {
1756	if (!copy_from_iter_full_nocache(addr: to, bytes: copy, i: from))
1757	return -EFAULT;
1758	} else if (!copy_from_iter_full(addr: to, bytes: copy, i: from)) {
1759	return -EFAULT;
1760	}
1761	return 0;
1762	}
1763
1764	/* open-code sk_stream_memory_free() plus sent limit computation to
1765	* avoid indirect calls in fast-path.
1766	* Called under the msk socket lock, so we can avoid a bunch of ONCE
1767	* annotations.
1768	*/
1769	static u32 mptcp_send_limit(const struct sock *sk)
1770	{
1771	const struct mptcp_sock *msk = mptcp_sk(sk);
1772	u32 limit, not_sent;
1773
1774	if (sk->sk_wmem_queued >= READ_ONCE(sk->sk_sndbuf))
1775	return 0;
1776
1777	limit = mptcp_notsent_lowat(sk);
1778	if (limit == UINT_MAX)
1779	return UINT_MAX;
1780
1781	not_sent = msk->write_seq - msk->snd_nxt;
1782	if (not_sent >= limit)
1783	return 0;
1784
1785	return limit - not_sent;
1786	}
1787
1788	static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
1789	{
1790	struct mptcp_sock *msk = mptcp_sk(sk);
1791	struct page_frag *pfrag;
1792	size_t copied = 0;
1793	int ret = 0;
1794	long timeo;
1795
1796	/* silently ignore everything else */
1797	msg->msg_flags &= MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL | MSG_FASTOPEN;
1798
1799	lock_sock(sk);
1800
1801	if (unlikely(inet_test_bit(DEFER_CONNECT, sk) ||
1802	msg->msg_flags & MSG_FASTOPEN)) {
1803	int copied_syn = 0;
1804
1805	ret = mptcp_sendmsg_fastopen(sk, msg, len, copied_syn: &copied_syn);
1806	copied += copied_syn;
1807	if (ret == -EINPROGRESS && copied_syn > 0)
1808	goto out;
1809	else if (ret)
1810	goto do_error;
1811	}
1812
1813	timeo = sock_sndtimeo(sk, noblock: msg->msg_flags & MSG_DONTWAIT);
1814
1815	if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) {
1816	ret = sk_stream_wait_connect(sk, timeo_p: &timeo);
1817	if (ret)
1818	goto do_error;
1819	}
1820
1821	ret = -EPIPE;
1822	if (unlikely(sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)))
1823	goto do_error;
1824
1825	pfrag = sk_page_frag(sk);
1826
1827	while (msg_data_left(msg)) {
1828	int total_ts, frag_truesize = 0;
1829	struct mptcp_data_frag *dfrag;
1830	bool dfrag_collapsed;
1831	size_t psize, offset;
1832	u32 copy_limit;
1833
1834	/* ensure fitting the notsent_lowat() constraint */
1835	copy_limit = mptcp_send_limit(sk);
1836	if (!copy_limit)
1837	goto wait_for_memory;
1838
1839	/* reuse tail pfrag, if possible, or carve a new one from the
1840	* page allocator
1841	*/
1842	dfrag = mptcp_pending_tail(sk);
1843	dfrag_collapsed = mptcp_frag_can_collapse_to(msk, pfrag, df: dfrag);
1844	if (!dfrag_collapsed) {
1845	if (!mptcp_page_frag_refill(sk, pfrag))
1846	goto wait_for_memory;
1847
1848	dfrag = mptcp_carve_data_frag(msk, pfrag, orig_offset: pfrag->offset);
1849	frag_truesize = dfrag->overhead;
1850	}
1851
1852	/* we do not bound vs wspace, to allow a single packet.
1853	* memory accounting will prevent execessive memory usage
1854	* anyway
1855	*/
1856	offset = dfrag->offset + dfrag->data_len;
1857	psize = pfrag->size - offset;
1858	psize = min_t(size_t, psize, msg_data_left(msg));
1859	psize = min_t(size_t, psize, copy_limit);
1860	total_ts = psize + frag_truesize;
1861
1862	if (!sk_wmem_schedule(sk, size: total_ts))
1863	goto wait_for_memory;
1864
1865	ret = do_copy_data_nocache(sk, copy: psize, from: &msg->msg_iter,
1866	page_address(dfrag->page) + offset);
1867	if (ret)
1868	goto do_error;
1869
1870	/* data successfully copied into the write queue */
1871	sk_forward_alloc_add(sk, val: -total_ts);
1872	copied += psize;
1873	dfrag->data_len += psize;
1874	frag_truesize += psize;
1875	pfrag->offset += frag_truesize;
1876	WRITE_ONCE(msk->write_seq, msk->write_seq + psize);
1877
1878	/* charge data on mptcp pending queue to the msk socket
1879	* Note: we charge such data both to sk and ssk
1880	*/
1881	sk_wmem_queued_add(sk, val: frag_truesize);
1882	if (!dfrag_collapsed) {
1883	get_page(page: dfrag->page);
1884	list_add_tail(new: &dfrag->list, head: &msk->rtx_queue);
1885	if (!msk->first_pending)
1886	WRITE_ONCE(msk->first_pending, dfrag);
1887	}
1888	pr_debug("msk=%p dfrag at seq=%llu len=%u sent=%u new=%d", msk,
1889	dfrag->data_seq, dfrag->data_len, dfrag->already_sent,
1890	!dfrag_collapsed);
1891
1892	continue;
1893
1894	wait_for_memory:
1895	set_bit(SOCK_NOSPACE, addr: &sk->sk_socket->flags);
1896	__mptcp_push_pending(sk, flags: msg->msg_flags);
1897	ret = sk_stream_wait_memory(sk, timeo_p: &timeo);
1898	if (ret)
1899	goto do_error;
1900	}
1901
1902	if (copied)
1903	__mptcp_push_pending(sk, flags: msg->msg_flags);
1904
1905	out:
1906	release_sock(sk);
1907	return copied;
1908
1909	do_error:
1910	if (copied)
1911	goto out;
1912
1913	copied = sk_stream_error(sk, flags: msg->msg_flags, err: ret);
1914	goto out;
1915	}
1916
1917	static int __mptcp_recvmsg_mskq(struct mptcp_sock *msk,
1918	struct msghdr *msg,
1919	size_t len, int flags,
1920	struct scm_timestamping_internal *tss,
1921	int *cmsg_flags)
1922	{
1923	struct sk_buff *skb, *tmp;
1924	int copied = 0;
1925
1926	skb_queue_walk_safe(&msk->receive_queue, skb, tmp) {
1927	u32 offset = MPTCP_SKB_CB(skb)->offset;
1928	u32 data_len = skb->len - offset;
1929	u32 count = min_t(size_t, len - copied, data_len);
1930	int err;
1931
1932	if (!(flags & MSG_TRUNC)) {
1933	err = skb_copy_datagram_msg(from: skb, offset, msg, size: count);
1934	if (unlikely(err < 0)) {
1935	if (!copied)
1936	return err;
1937	break;
1938	}
1939	}
1940
1941	if (MPTCP_SKB_CB(skb)->has_rxtstamp) {
1942	tcp_update_recv_tstamps(skb, tss);
1943	*cmsg_flags |= MPTCP_CMSG_TS;
1944	}
1945
1946	copied += count;
1947
1948	if (count < data_len) {
1949	if (!(flags & MSG_PEEK)) {
1950	MPTCP_SKB_CB(skb)->offset += count;
1951	MPTCP_SKB_CB(skb)->map_seq += count;
1952	msk->bytes_consumed += count;
1953	}
1954	break;
1955	}
1956
1957	if (!(flags & MSG_PEEK)) {
1958	/* we will bulk release the skb memory later */
1959	skb->destructor = NULL;
1960	WRITE_ONCE(msk->rmem_released, msk->rmem_released + skb->truesize);
1961	__skb_unlink(skb, list: &msk->receive_queue);
1962	__kfree_skb(skb);
1963	msk->bytes_consumed += count;
1964	}
1965
1966	if (copied >= len)
1967	break;
1968	}
1969
1970	return copied;
1971	}
1972
1973	/* receive buffer autotuning. See tcp_rcv_space_adjust for more information.
1974	*
1975	* Only difference: Use highest rtt estimate of the subflows in use.
1976	*/
1977	static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied)
1978	{
1979	struct mptcp_subflow_context *subflow;
1980	struct sock *sk = (struct sock *)msk;
1981	u8 scaling_ratio = U8_MAX;
1982	u32 time, advmss = 1;
1983	u64 rtt_us, mstamp;
1984
1985	msk_owned_by_me(msk);
1986
1987	if (copied <= 0)
1988	return;
1989
1990	if (!msk->rcvspace_init)
1991	mptcp_rcv_space_init(msk, ssk: msk->first);
1992
1993	msk->rcvq_space.copied += copied;
1994
1995	mstamp = div_u64(dividend: tcp_clock_ns(), NSEC_PER_USEC);
1996	time = tcp_stamp_us_delta(t1: mstamp, t0: msk->rcvq_space.time);
1997
1998	rtt_us = msk->rcvq_space.rtt_us;
1999	if (rtt_us && time < (rtt_us >> 3))
2000	return;
2001
2002	rtt_us = 0;
2003	mptcp_for_each_subflow(msk, subflow) {
2004	const struct tcp_sock *tp;
2005	u64 sf_rtt_us;
2006	u32 sf_advmss;
2007
2008	tp = tcp_sk(mptcp_subflow_tcp_sock(subflow));
2009
2010	sf_rtt_us = READ_ONCE(tp->rcv_rtt_est.rtt_us);
2011	sf_advmss = READ_ONCE(tp->advmss);
2012
2013	rtt_us = max(sf_rtt_us, rtt_us);
2014	advmss = max(sf_advmss, advmss);
2015	scaling_ratio = min(tp->scaling_ratio, scaling_ratio);
2016	}
2017
2018	msk->rcvq_space.rtt_us = rtt_us;
2019	msk->scaling_ratio = scaling_ratio;
2020	if (time < (rtt_us >> 3) || rtt_us == 0)
2021	return;
2022
2023	if (msk->rcvq_space.copied <= msk->rcvq_space.space)
2024	goto new_measure;
2025
2026	if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_moderate_rcvbuf) &&
2027	!(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
2028	u64 rcvwin, grow;
2029	int rcvbuf;
2030
2031	rcvwin = ((u64)msk->rcvq_space.copied << 1) + 16 * advmss;
2032
2033	grow = rcvwin * (msk->rcvq_space.copied - msk->rcvq_space.space);
2034
2035	do_div(grow, msk->rcvq_space.space);
2036	rcvwin += (grow << 1);
2037
2038	rcvbuf = min_t(u64, __tcp_space_from_win(scaling_ratio, rcvwin),
2039	READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[2]));
2040
2041	if (rcvbuf > sk->sk_rcvbuf) {
2042	u32 window_clamp;
2043
2044	window_clamp = __tcp_win_from_space(scaling_ratio, space: rcvbuf);
2045	WRITE_ONCE(sk->sk_rcvbuf, rcvbuf);
2046
2047	/* Make subflows follow along. If we do not do this, we
2048	* get drops at subflow level if skbs can't be moved to
2049	* the mptcp rx queue fast enough (announced rcv_win can
2050	* exceed ssk->sk_rcvbuf).
2051	*/
2052	mptcp_for_each_subflow(msk, subflow) {
2053	struct sock *ssk;
2054	bool slow;
2055
2056	ssk = mptcp_subflow_tcp_sock(subflow);
2057	slow = lock_sock_fast(sk: ssk);
2058	WRITE_ONCE(ssk->sk_rcvbuf, rcvbuf);
2059	tcp_sk(ssk)->window_clamp = window_clamp;
2060	tcp_cleanup_rbuf(sk: ssk, copied: 1);
2061	unlock_sock_fast(sk: ssk, slow);
2062	}
2063	}
2064	}
2065
2066	msk->rcvq_space.space = msk->rcvq_space.copied;
2067	new_measure:
2068	msk->rcvq_space.copied = 0;
2069	msk->rcvq_space.time = mstamp;
2070	}
2071
2072	static void __mptcp_update_rmem(struct sock *sk)
2073	{
2074	struct mptcp_sock *msk = mptcp_sk(sk);
2075
2076	if (!msk->rmem_released)
2077	return;
2078
2079	atomic_sub(i: msk->rmem_released, v: &sk->sk_rmem_alloc);
2080	mptcp_rmem_uncharge(sk, size: msk->rmem_released);
2081	WRITE_ONCE(msk->rmem_released, 0);
2082	}
2083
2084	static void __mptcp_splice_receive_queue(struct sock *sk)
2085	{
2086	struct mptcp_sock *msk = mptcp_sk(sk);
2087
2088	skb_queue_splice_tail_init(list: &sk->sk_receive_queue, head: &msk->receive_queue);
2089	}
2090
2091	static bool __mptcp_move_skbs(struct mptcp_sock *msk)
2092	{
2093	struct sock *sk = (struct sock *)msk;
2094	unsigned int moved = 0;
2095	bool ret, done;
2096
2097	do {
2098	struct sock *ssk = mptcp_subflow_recv_lookup(msk);
2099	bool slowpath;
2100
2101	/* we can have data pending in the subflows only if the msk
2102	* receive buffer was full at subflow_data_ready() time,
2103	* that is an unlikely slow path.
2104	*/
2105	if (likely(!ssk))
2106	break;
2107
2108	slowpath = lock_sock_fast(sk: ssk);
2109	mptcp_data_lock(sk);
2110	__mptcp_update_rmem(sk);
2111	done = __mptcp_move_skbs_from_subflow(msk, ssk, bytes: &moved);
2112	mptcp_data_unlock(sk);
2113
2114	if (unlikely(ssk->sk_err))
2115	__mptcp_error_report(sk);
2116	unlock_sock_fast(sk: ssk, slow: slowpath);
2117	} while (!done);
2118
2119	/* acquire the data lock only if some input data is pending */
2120	ret = moved > 0;
2121	if (!RB_EMPTY_ROOT(&msk->out_of_order_queue) ||
2122	!skb_queue_empty_lockless(list: &sk->sk_receive_queue)) {
2123	mptcp_data_lock(sk);
2124	__mptcp_update_rmem(sk);
2125	ret |= __mptcp_ofo_queue(msk);
2126	__mptcp_splice_receive_queue(sk);
2127	mptcp_data_unlock(sk);
2128	}
2129	if (ret)
2130	mptcp_check_data_fin(sk: (struct sock *)msk);
2131	return !skb_queue_empty(list: &msk->receive_queue);
2132	}
2133
2134	static unsigned int mptcp_inq_hint(const struct sock *sk)
2135	{
2136	const struct mptcp_sock *msk = mptcp_sk(sk);
2137	const struct sk_buff *skb;
2138
2139	skb = skb_peek(list_: &msk->receive_queue);
2140	if (skb) {
2141	u64 hint_val = READ_ONCE(msk->ack_seq) - MPTCP_SKB_CB(skb)->map_seq;
2142
2143	if (hint_val >= INT_MAX)
2144	return INT_MAX;
2145
2146	return (unsigned int)hint_val;
2147	}
2148
2149	if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
2150	return 1;
2151
2152	return 0;
2153	}
2154
2155	static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
2156	int flags, int *addr_len)
2157	{
2158	struct mptcp_sock *msk = mptcp_sk(sk);
2159	struct scm_timestamping_internal tss;
2160	int copied = 0, cmsg_flags = 0;
2161	int target;
2162	long timeo;
2163
2164	/* MSG_ERRQUEUE is really a no-op till we support IP_RECVERR */
2165	if (unlikely(flags & MSG_ERRQUEUE))
2166	return inet_recv_error(sk, msg, len, addr_len);
2167
2168	lock_sock(sk);
2169	if (unlikely(sk->sk_state == TCP_LISTEN)) {
2170	copied = -ENOTCONN;
2171	goto out_err;
2172	}
2173
2174	timeo = sock_rcvtimeo(sk, noblock: flags & MSG_DONTWAIT);
2175
2176	len = min_t(size_t, len, INT_MAX);
2177	target = sock_rcvlowat(sk, waitall: flags & MSG_WAITALL, len);
2178
2179	if (unlikely(msk->recvmsg_inq))
2180	cmsg_flags = MPTCP_CMSG_INQ;
2181
2182	while (copied < len) {
2183	int bytes_read;
2184
2185	bytes_read = __mptcp_recvmsg_mskq(msk, msg, len: len - copied, flags, tss: &tss, cmsg_flags: &cmsg_flags);
2186	if (unlikely(bytes_read < 0)) {
2187	if (!copied)
2188	copied = bytes_read;
2189	goto out_err;
2190	}
2191
2192	copied += bytes_read;
2193
2194	/* be sure to advertise window change */
2195	mptcp_cleanup_rbuf(msk);
2196
2197	if (skb_queue_empty(list: &msk->receive_queue) && __mptcp_move_skbs(msk))
2198	continue;
2199
2200	/* only the master socket status is relevant here. The exit
2201	* conditions mirror closely tcp_recvmsg()
2202	*/
2203	if (copied >= target)
2204	break;
2205
2206	if (copied) {
2207	if (sk->sk_err ||
2208	sk->sk_state == TCP_CLOSE ||
2209	(sk->sk_shutdown & RCV_SHUTDOWN) ||
2210	!timeo ||
2211	signal_pending(current))
2212	break;
2213	} else {
2214	if (sk->sk_err) {
2215	copied = sock_error(sk);
2216	break;
2217	}
2218
2219	if (sk->sk_shutdown & RCV_SHUTDOWN) {
2220	/* race breaker: the shutdown could be after the
2221	* previous receive queue check
2222	*/
2223	if (__mptcp_move_skbs(msk))
2224	continue;
2225	break;
2226	}
2227
2228	if (sk->sk_state == TCP_CLOSE) {
2229	copied = -ENOTCONN;
2230	break;
2231	}
2232
2233	if (!timeo) {
2234	copied = -EAGAIN;
2235	break;
2236	}
2237
2238	if (signal_pending(current)) {
2239	copied = sock_intr_errno(timeo);
2240	break;
2241	}
2242	}
2243
2244	pr_debug("block timeout %ld", timeo);
2245	sk_wait_data(sk, timeo: &timeo, NULL);
2246	}
2247
2248	out_err:
2249	if (cmsg_flags && copied >= 0) {
2250	if (cmsg_flags & MPTCP_CMSG_TS)
2251	tcp_recv_timestamp(msg, sk, tss: &tss);
2252
2253	if (cmsg_flags & MPTCP_CMSG_INQ) {
2254	unsigned int inq = mptcp_inq_hint(sk);
2255
2256	put_cmsg(msg, SOL_TCP, TCP_CM_INQ, len: sizeof(inq), data: &inq);
2257	}
2258	}
2259
2260	pr_debug("msk=%p rx queue empty=%d:%d copied=%d",
2261	msk, skb_queue_empty_lockless(&sk->sk_receive_queue),
2262	skb_queue_empty(&msk->receive_queue), copied);
2263	if (!(flags & MSG_PEEK))
2264	mptcp_rcv_space_adjust(msk, copied);
2265
2266	release_sock(sk);
2267	return copied;
2268	}
2269
2270	static void mptcp_retransmit_timer(struct timer_list *t)
2271	{
2272	struct inet_connection_sock *icsk = from_timer(icsk, t,
2273	icsk_retransmit_timer);
2274	struct sock *sk = &icsk->icsk_inet.sk;
2275	struct mptcp_sock *msk = mptcp_sk(sk);
2276
2277	bh_lock_sock(sk);
2278	if (!sock_owned_by_user(sk)) {
2279	/* we need a process context to retransmit */
2280	if (!test_and_set_bit(MPTCP_WORK_RTX, addr: &msk->flags))
2281	mptcp_schedule_work(sk);
2282	} else {
2283	/* delegate our work to tcp_release_cb() */
2284	__set_bit(MPTCP_RETRANSMIT, &msk->cb_flags);
2285	}
2286	bh_unlock_sock(sk);
2287	sock_put(sk);
2288	}
2289
2290	static void mptcp_tout_timer(struct timer_list *t)
2291	{
2292	struct sock *sk = from_timer(sk, t, sk_timer);
2293
2294	mptcp_schedule_work(sk);
2295	sock_put(sk);
2296	}
2297
2298	/* Find an idle subflow. Return NULL if there is unacked data at tcp
2299	* level.
2300	*
2301	* A backup subflow is returned only if that is the only kind available.
2302	*/
2303	struct sock *mptcp_subflow_get_retrans(struct mptcp_sock *msk)
2304	{
2305	struct sock *backup = NULL, *pick = NULL;
2306	struct mptcp_subflow_context *subflow;
2307	int min_stale_count = INT_MAX;
2308
2309	mptcp_for_each_subflow(msk, subflow) {
2310	struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
2311
2312	if (!__mptcp_subflow_active(subflow))
2313	continue;
2314
2315	/* still data outstanding at TCP level? skip this */
2316	if (!tcp_rtx_and_write_queues_empty(sk: ssk)) {
2317	mptcp_pm_subflow_chk_stale(msk, ssk);
2318	min_stale_count = min_t(int, min_stale_count, subflow->stale_count);
2319	continue;
2320	}
2321
2322	if (subflow->backup) {
2323	if (!backup)
2324	backup = ssk;
2325	continue;
2326	}
2327
2328	if (!pick)
2329	pick = ssk;
2330	}
2331
2332	if (pick)
2333	return pick;
2334
2335	/* use backup only if there are no progresses anywhere */
2336	return min_stale_count > 1 ? backup : NULL;
2337	}
2338
2339	bool __mptcp_retransmit_pending_data(struct sock *sk)
2340	{
2341	struct mptcp_data_frag *cur, *rtx_head;
2342	struct mptcp_sock *msk = mptcp_sk(sk);
2343
2344	if (__mptcp_check_fallback(msk))
2345	return false;
2346
2347	/* the closing socket has some data untransmitted and/or unacked:
2348	* some data in the mptcp rtx queue has not really xmitted yet.
2349	* keep it simple and re-inject the whole mptcp level rtx queue
2350	*/
2351	mptcp_data_lock(sk);
2352	__mptcp_clean_una_wakeup(sk);
2353	rtx_head = mptcp_rtx_head(sk);
2354	if (!rtx_head) {
2355	mptcp_data_unlock(sk);
2356	return false;
2357	}
2358
2359	msk->recovery_snd_nxt = msk->snd_nxt;
2360	msk->recovery = true;
2361	mptcp_data_unlock(sk);
2362
2363	msk->first_pending = rtx_head;
2364	msk->snd_burst = 0;
2365
2366	/* be sure to clear the "sent status" on all re-injected fragments */
2367	list_for_each_entry(cur, &msk->rtx_queue, list) {
2368	if (!cur->already_sent)
2369	break;
2370	cur->already_sent = 0;
2371	}
2372
2373	return true;
2374	}
2375
2376	/* flags for __mptcp_close_ssk() */
2377	#define MPTCP_CF_PUSH BIT(1)
2378	#define MPTCP_CF_FASTCLOSE BIT(2)
2379
2380	/* be sure to send a reset only if the caller asked for it, also
2381	* clean completely the subflow status when the subflow reaches
2382	* TCP_CLOSE state
2383	*/
2384	static void __mptcp_subflow_disconnect(struct sock *ssk,
2385	struct mptcp_subflow_context *subflow,
2386	unsigned int flags)
2387	{
2388	if (((1 << ssk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) ||
2389	(flags & MPTCP_CF_FASTCLOSE)) {
2390	/* The MPTCP code never wait on the subflow sockets, TCP-level
2391	* disconnect should never fail
2392	*/
2393	WARN_ON_ONCE(tcp_disconnect(ssk, 0));
2394	mptcp_subflow_ctx_reset(subflow);
2395	} else {
2396	tcp_shutdown(sk: ssk, SEND_SHUTDOWN);
2397	}
2398	}
2399
2400	/* subflow sockets can be either outgoing (connect) or incoming
2401	* (accept).
2402	*
2403	* Outgoing subflows use in-kernel sockets.
2404	* Incoming subflows do not have their own 'struct socket' allocated,
2405	* so we need to use tcp_close() after detaching them from the mptcp
2406	* parent socket.
2407	*/
2408	static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
2409	struct mptcp_subflow_context *subflow,
2410	unsigned int flags)
2411	{
2412	struct mptcp_sock *msk = mptcp_sk(sk);
2413	bool dispose_it, need_push = false;
2414
2415	/* If the first subflow moved to a close state before accept, e.g. due
2416	* to an incoming reset or listener shutdown, the subflow socket is
2417	* already deleted by inet_child_forget() and the mptcp socket can't
2418	* survive too.
2419	*/
2420	if (msk->in_accept_queue && msk->first == ssk &&
2421	(sock_flag(sk, flag: SOCK_DEAD) || sock_flag(sk: ssk, flag: SOCK_DEAD))) {
2422	/* ensure later check in mptcp_worker() will dispose the msk */
2423	sock_set_flag(sk, flag: SOCK_DEAD);
2424	mptcp_set_close_tout(sk, tcp_jiffies32 - (mptcp_close_timeout(sk) + 1));
2425	lock_sock_nested(sk: ssk, SINGLE_DEPTH_NESTING);
2426	mptcp_subflow_drop_ctx(ssk);
2427	goto out_release;
2428	}
2429
2430	dispose_it = msk->free_first || ssk != msk->first;
2431	if (dispose_it)
2432	list_del(entry: &subflow->node);
2433
2434	lock_sock_nested(sk: ssk, SINGLE_DEPTH_NESTING);
2435
2436	if ((flags & MPTCP_CF_FASTCLOSE) && !__mptcp_check_fallback(msk)) {
2437	/* be sure to force the tcp_close path
2438	* to generate the egress reset
2439	*/
2440	ssk->sk_lingertime = 0;
2441	sock_set_flag(sk: ssk, flag: SOCK_LINGER);
2442	subflow->send_fastclose = 1;
2443	}
2444
2445	need_push = (flags & MPTCP_CF_PUSH) && __mptcp_retransmit_pending_data(sk);
2446	if (!dispose_it) {
2447	__mptcp_subflow_disconnect(ssk, subflow, flags);
2448	release_sock(sk: ssk);
2449
2450	goto out;
2451	}
2452
2453	subflow->disposable = 1;
2454
2455	/* if ssk hit tcp_done(), tcp_cleanup_ulp() cleared the related ops
2456	* the ssk has been already destroyed, we just need to release the
2457	* reference owned by msk;
2458	*/
2459	if (!inet_csk(sk: ssk)->icsk_ulp_ops) {
2460	WARN_ON_ONCE(!sock_flag(ssk, SOCK_DEAD));
2461	kfree_rcu(subflow, rcu);
2462	} else {
2463	/* otherwise tcp will dispose of the ssk and subflow ctx */
2464	__tcp_close(sk: ssk, timeout: 0);
2465
2466	/* close acquired an extra ref */
2467	__sock_put(sk: ssk);
2468	}
2469
2470	out_release:
2471	__mptcp_subflow_error_report(sk, ssk);
2472	release_sock(sk: ssk);
2473
2474	sock_put(sk: ssk);
2475
2476	if (ssk == msk->first)
2477	WRITE_ONCE(msk->first, NULL);
2478
2479	out:
2480	__mptcp_sync_sndbuf(sk);
2481	if (need_push)
2482	__mptcp_push_pending(sk, flags: 0);
2483
2484	/* Catch every 'all subflows closed' scenario, including peers silently
2485	* closing them, e.g. due to timeout.
2486	* For established sockets, allow an additional timeout before closing,
2487	* as the protocol can still create more subflows.
2488	*/
2489	if (list_is_singular(head: &msk->conn_list) && msk->first &&
2490	inet_sk_state_load(sk: msk->first) == TCP_CLOSE) {
2491	if (sk->sk_state != TCP_ESTABLISHED ||
2492	msk->in_accept_queue || sock_flag(sk, flag: SOCK_DEAD)) {
2493	mptcp_set_state(sk, state: TCP_CLOSE);
2494	mptcp_close_wake_up(sk);
2495	} else {
2496	mptcp_start_tout_timer(sk);
2497	}
2498	}
2499	}
2500
2501	void mptcp_close_ssk(struct sock *sk, struct sock *ssk,
2502	struct mptcp_subflow_context *subflow)
2503	{
2504	if (sk->sk_state == TCP_ESTABLISHED)
2505	mptcp_event(type: MPTCP_EVENT_SUB_CLOSED, mptcp_sk(sk), ssk, GFP_KERNEL);
2506
2507	/* subflow aborted before reaching the fully_established status
2508	* attempt the creation of the next subflow
2509	*/
2510	mptcp_pm_subflow_check_next(mptcp_sk(sk), subflow);
2511
2512	__mptcp_close_ssk(sk, ssk, subflow, MPTCP_CF_PUSH);
2513	}
2514
2515	static unsigned int mptcp_sync_mss(struct sock *sk, u32 pmtu)
2516	{
2517	return 0;
2518	}
2519
2520	static void __mptcp_close_subflow(struct sock *sk)
2521	{
2522	struct mptcp_subflow_context *subflow, *tmp;
2523	struct mptcp_sock *msk = mptcp_sk(sk);
2524
2525	might_sleep();
2526
2527	mptcp_for_each_subflow_safe(msk, subflow, tmp) {
2528	struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
2529
2530	if (inet_sk_state_load(sk: ssk) != TCP_CLOSE)
2531	continue;
2532
2533	/* 'subflow_data_ready' will re-sched once rx queue is empty */
2534	if (!skb_queue_empty_lockless(list: &ssk->sk_receive_queue))
2535	continue;
2536
2537	mptcp_close_ssk(sk, ssk, subflow);
2538	}
2539
2540	}
2541
2542	static bool mptcp_close_tout_expired(const struct sock *sk)
2543	{
2544	if (!inet_csk(sk)->icsk_mtup.probe_timestamp ||
2545	sk->sk_state == TCP_CLOSE)
2546	return false;
2547
2548	return time_after32(tcp_jiffies32,
2549	inet_csk(sk)->icsk_mtup.probe_timestamp + mptcp_close_timeout(sk));
2550	}
2551
2552	static void mptcp_check_fastclose(struct mptcp_sock *msk)
2553	{
2554	struct mptcp_subflow_context *subflow, *tmp;
2555	struct sock *sk = (struct sock *)msk;
2556
2557	if (likely(!READ_ONCE(msk->rcv_fastclose)))
2558	return;
2559
2560	mptcp_token_destroy(msk);
2561
2562	mptcp_for_each_subflow_safe(msk, subflow, tmp) {
2563	struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow);
2564	bool slow;
2565
2566	slow = lock_sock_fast(sk: tcp_sk);
2567	if (tcp_sk->sk_state != TCP_CLOSE) {
2568	tcp_send_active_reset(sk: tcp_sk, GFP_ATOMIC);
2569	tcp_set_state(sk: tcp_sk, state: TCP_CLOSE);
2570	}
2571	unlock_sock_fast(sk: tcp_sk, slow);
2572	}
2573
2574	/* Mirror the tcp_reset() error propagation */
2575	switch (sk->sk_state) {
2576	case TCP_SYN_SENT:
2577	WRITE_ONCE(sk->sk_err, ECONNREFUSED);
2578	break;
2579	case TCP_CLOSE_WAIT:
2580	WRITE_ONCE(sk->sk_err, EPIPE);
2581	break;
2582	case TCP_CLOSE:
2583	return;
2584	default:
2585	WRITE_ONCE(sk->sk_err, ECONNRESET);
2586	}
2587
2588	mptcp_set_state(sk, state: TCP_CLOSE);
2589	WRITE_ONCE(sk->sk_shutdown, SHUTDOWN_MASK);
2590	smp_mb__before_atomic(); /* SHUTDOWN must be visible first */
2591	set_bit(MPTCP_WORK_CLOSE_SUBFLOW, addr: &msk->flags);
2592
2593	/* the calling mptcp_worker will properly destroy the socket */
2594	if (sock_flag(sk, flag: SOCK_DEAD))
2595	return;
2596
2597	sk->sk_state_change(sk);
2598	sk_error_report(sk);
2599	}
2600
2601	static void __mptcp_retrans(struct sock *sk)
2602	{
2603	struct mptcp_sock *msk = mptcp_sk(sk);
2604	struct mptcp_subflow_context *subflow;
2605	struct mptcp_sendmsg_info info = {};
2606	struct mptcp_data_frag *dfrag;
2607	struct sock *ssk;
2608	int ret, err;
2609	u16 len = 0;
2610
2611	mptcp_clean_una_wakeup(sk);
2612
2613	/* first check ssk: need to kick "stale" logic */
2614	err = mptcp_sched_get_retrans(msk);
2615	dfrag = mptcp_rtx_head(sk);
2616	if (!dfrag) {
2617	if (mptcp_data_fin_enabled(msk)) {
2618	struct inet_connection_sock *icsk = inet_csk(sk);
2619
2620	icsk->icsk_retransmits++;
2621	mptcp_set_datafin_timeout(sk);
2622	mptcp_send_ack(msk);
2623
2624	goto reset_timer;
2625	}
2626
2627	if (!mptcp_send_head(sk))
2628	return;
2629
2630	goto reset_timer;
2631	}
2632
2633	if (err)
2634	goto reset_timer;
2635
2636	mptcp_for_each_subflow(msk, subflow) {
2637	if (READ_ONCE(subflow->scheduled)) {
2638	u16 copied = 0;
2639
2640	mptcp_subflow_set_scheduled(subflow, scheduled: false);
2641
2642	ssk = mptcp_subflow_tcp_sock(subflow);
2643
2644	lock_sock(sk: ssk);
2645
2646	/* limit retransmission to the bytes already sent on some subflows */
2647	info.sent = 0;
2648	info.limit = READ_ONCE(msk->csum_enabled) ? dfrag->data_len :
2649	dfrag->already_sent;
2650	while (info.sent < info.limit) {
2651	ret = mptcp_sendmsg_frag(sk, ssk, dfrag, info: &info);
2652	if (ret <= 0)
2653	break;
2654
2655	MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_RETRANSSEGS);
2656	copied += ret;
2657	info.sent += ret;
2658	}
2659	if (copied) {
2660	len = max(copied, len);
2661	tcp_push(sk: ssk, flags: 0, mss_now: info.mss_now, tcp_sk(ssk)->nonagle,
2662	size_goal: info.size_goal);
2663	WRITE_ONCE(msk->allow_infinite_fallback, false);
2664	}
2665
2666	release_sock(sk: ssk);
2667	}
2668	}
2669
2670	msk->bytes_retrans += len;
2671	dfrag->already_sent = max(dfrag->already_sent, len);
2672
2673	reset_timer:
2674	mptcp_check_and_set_pending(sk);
2675
2676	if (!mptcp_rtx_timer_pending(sk))
2677	mptcp_reset_rtx_timer(sk);
2678	}
2679
2680	/* schedule the timeout timer for the relevant event: either close timeout
2681	* or mp_fail timeout. The close timeout takes precedence on the mp_fail one
2682	*/
2683	void mptcp_reset_tout_timer(struct mptcp_sock *msk, unsigned long fail_tout)
2684	{
2685	struct sock *sk = (struct sock *)msk;
2686	unsigned long timeout, close_timeout;
2687
2688	if (!fail_tout && !inet_csk(sk)->icsk_mtup.probe_timestamp)
2689	return;
2690
2691	close_timeout = inet_csk(sk)->icsk_mtup.probe_timestamp - tcp_jiffies32 + jiffies +
2692	mptcp_close_timeout(sk);
2693
2694	/* the close timeout takes precedence on the fail one, and here at least one of
2695	* them is active
2696	*/
2697	timeout = inet_csk(sk)->icsk_mtup.probe_timestamp ? close_timeout : fail_tout;
2698
2699	sk_reset_timer(sk, timer: &sk->sk_timer, expires: timeout);
2700	}
2701
2702	static void mptcp_mp_fail_no_response(struct mptcp_sock *msk)
2703	{
2704	struct sock *ssk = msk->first;
2705	bool slow;
2706
2707	if (!ssk)
2708	return;
2709
2710	pr_debug("MP_FAIL doesn't respond, reset the subflow");
2711
2712	slow = lock_sock_fast(sk: ssk);
2713	mptcp_subflow_reset(ssk);
2714	WRITE_ONCE(mptcp_subflow_ctx(ssk)->fail_tout, 0);
2715	unlock_sock_fast(sk: ssk, slow);
2716	}
2717
2718	static void mptcp_do_fastclose(struct sock *sk)
2719	{
2720	struct mptcp_subflow_context *subflow, *tmp;
2721	struct mptcp_sock *msk = mptcp_sk(sk);
2722
2723	mptcp_set_state(sk, state: TCP_CLOSE);
2724	mptcp_for_each_subflow_safe(msk, subflow, tmp)
2725	__mptcp_close_ssk(sk, ssk: mptcp_subflow_tcp_sock(subflow),
2726	subflow, MPTCP_CF_FASTCLOSE);
2727	}
2728
2729	static void mptcp_worker(struct work_struct *work)
2730	{
2731	struct mptcp_sock *msk = container_of(work, struct mptcp_sock, work);
2732	struct sock *sk = (struct sock *)msk;
2733	unsigned long fail_tout;
2734	int state;
2735
2736	lock_sock(sk);
2737	state = sk->sk_state;
2738	if (unlikely((1 << state) & (TCPF_CLOSE | TCPF_LISTEN)))
2739	goto unlock;
2740
2741	mptcp_check_fastclose(msk);
2742
2743	mptcp_pm_nl_work(msk);
2744
2745	mptcp_check_send_data_fin(sk);
2746	mptcp_check_data_fin_ack(sk);
2747	mptcp_check_data_fin(sk);
2748
2749	if (test_and_clear_bit(MPTCP_WORK_CLOSE_SUBFLOW, addr: &msk->flags))
2750	__mptcp_close_subflow(sk);
2751
2752	if (mptcp_close_tout_expired(sk)) {
2753	mptcp_do_fastclose(sk);
2754	mptcp_close_wake_up(sk);
2755	}
2756
2757	if (sock_flag(sk, flag: SOCK_DEAD) && sk->sk_state == TCP_CLOSE) {
2758	__mptcp_destroy_sock(sk);
2759	goto unlock;
2760	}
2761
2762	if (test_and_clear_bit(MPTCP_WORK_RTX, addr: &msk->flags))
2763	__mptcp_retrans(sk);
2764
2765	fail_tout = msk->first ? READ_ONCE(mptcp_subflow_ctx(msk->first)->fail_tout) : 0;
2766	if (fail_tout && time_after(jiffies, fail_tout))
2767	mptcp_mp_fail_no_response(msk);
2768
2769	unlock:
2770	release_sock(sk);
2771	sock_put(sk);
2772	}
2773
2774	static void __mptcp_init_sock(struct sock *sk)
2775	{
2776	struct mptcp_sock *msk = mptcp_sk(sk);
2777
2778	INIT_LIST_HEAD(list: &msk->conn_list);
2779	INIT_LIST_HEAD(list: &msk->join_list);
2780	INIT_LIST_HEAD(list: &msk->rtx_queue);
2781	INIT_WORK(&msk->work, mptcp_worker);
2782	__skb_queue_head_init(list: &msk->receive_queue);
2783	msk->out_of_order_queue = RB_ROOT;
2784	msk->first_pending = NULL;
2785	WRITE_ONCE(msk->rmem_fwd_alloc, 0);
2786	WRITE_ONCE(msk->rmem_released, 0);
2787	msk->timer_ival = TCP_RTO_MIN;
2788	msk->scaling_ratio = TCP_DEFAULT_SCALING_RATIO;
2789
2790	WRITE_ONCE(msk->first, NULL);
2791	inet_csk(sk)->icsk_sync_mss = mptcp_sync_mss;
2792	WRITE_ONCE(msk->csum_enabled, mptcp_is_checksum_enabled(sock_net(sk)));
2793	WRITE_ONCE(msk->allow_infinite_fallback, true);
2794	msk->recovery = false;
2795	msk->subflow_id = 1;
2796
2797	mptcp_pm_data_init(msk);
2798
2799	/* re-use the csk retrans timer for MPTCP-level retrans */
2800	timer_setup(&msk->sk.icsk_retransmit_timer, mptcp_retransmit_timer, 0);
2801	timer_setup(&sk->sk_timer, mptcp_tout_timer, 0);
2802	}
2803
2804	static void mptcp_ca_reset(struct sock *sk)
2805	{
2806	struct inet_connection_sock *icsk = inet_csk(sk);
2807
2808	tcp_assign_congestion_control(sk);
2809	strcpy(mptcp_sk(sk)->ca_name, q: icsk->icsk_ca_ops->name);
2810
2811	/* no need to keep a reference to the ops, the name will suffice */
2812	tcp_cleanup_congestion_control(sk);
2813	icsk->icsk_ca_ops = NULL;
2814	}
2815
2816	static int mptcp_init_sock(struct sock *sk)
2817	{
2818	struct net *net = sock_net(sk);
2819	int ret;
2820
2821	__mptcp_init_sock(sk);
2822
2823	if (!mptcp_is_enabled(net))
2824	return -ENOPROTOOPT;
2825
2826	if (unlikely(!net->mib.mptcp_statistics) && !mptcp_mib_alloc(net))
2827	return -ENOMEM;
2828
2829	ret = mptcp_init_sched(mptcp_sk(sk),
2830	sched: mptcp_sched_find(name: mptcp_get_scheduler(net)));
2831	if (ret)
2832	return ret;
2833
2834	set_bit(SOCK_CUSTOM_SOCKOPT, addr: &sk->sk_socket->flags);
2835
2836	/* fetch the ca name; do it outside __mptcp_init_sock(), so that clone will
2837	* propagate the correct value
2838	*/
2839	mptcp_ca_reset(sk);
2840
2841	sk_sockets_allocated_inc(sk);
2842	sk->sk_rcvbuf = READ_ONCE(net->ipv4.sysctl_tcp_rmem[1]);
2843	sk->sk_sndbuf = READ_ONCE(net->ipv4.sysctl_tcp_wmem[1]);
2844
2845	return 0;
2846	}
2847
2848	static void __mptcp_clear_xmit(struct sock *sk)
2849	{
2850	struct mptcp_sock *msk = mptcp_sk(sk);
2851	struct mptcp_data_frag *dtmp, *dfrag;
2852
2853	WRITE_ONCE(msk->first_pending, NULL);
2854	list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list)
2855	dfrag_clear(sk, dfrag);
2856	}
2857
2858	void mptcp_cancel_work(struct sock *sk)
2859	{
2860	struct mptcp_sock *msk = mptcp_sk(sk);
2861
2862	if (cancel_work_sync(work: &msk->work))
2863	__sock_put(sk);
2864	}
2865
2866	void mptcp_subflow_shutdown(struct sock *sk, struct sock *ssk, int how)
2867	{
2868	lock_sock(sk: ssk);
2869
2870	switch (ssk->sk_state) {
2871	case TCP_LISTEN:
2872	if (!(how & RCV_SHUTDOWN))
2873	break;
2874	fallthrough;
2875	case TCP_SYN_SENT:
2876	WARN_ON_ONCE(tcp_disconnect(ssk, O_NONBLOCK));
2877	break;
2878	default:
2879	if (__mptcp_check_fallback(mptcp_sk(sk))) {
2880	pr_debug("Fallback");
2881	ssk->sk_shutdown |= how;
2882	tcp_shutdown(sk: ssk, how);
2883
2884	/* simulate the data_fin ack reception to let the state
2885	* machine move forward
2886	*/
2887	WRITE_ONCE(mptcp_sk(sk)->snd_una, mptcp_sk(sk)->snd_nxt);
2888	mptcp_schedule_work(sk);
2889	} else {
2890	pr_debug("Sending DATA_FIN on subflow %p", ssk);
2891	tcp_send_ack(sk: ssk);
2892	if (!mptcp_rtx_timer_pending(sk))
2893	mptcp_reset_rtx_timer(sk);
2894	}
2895	break;
2896	}
2897
2898	release_sock(sk: ssk);
2899	}
2900
2901	void mptcp_set_state(struct sock *sk, int state)
2902	{
2903	int oldstate = sk->sk_state;
2904
2905	switch (state) {
2906	case TCP_ESTABLISHED:
2907	if (oldstate != TCP_ESTABLISHED)
2908	MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_CURRESTAB);
2909	break;
2910
2911	default:
2912	if (oldstate == TCP_ESTABLISHED)
2913	MPTCP_DEC_STATS(net: sock_net(sk), field: MPTCP_MIB_CURRESTAB);
2914	}
2915
2916	inet_sk_state_store(sk, newstate: state);
2917	}
2918
2919	static const unsigned char new_state[16] = {
2920	/* current state: new state: action: */
2921	[0 /* (Invalid) */] = TCP_CLOSE,
2922	[TCP_ESTABLISHED] = TCP_FIN_WAIT1 | TCP_ACTION_FIN,
2923	[TCP_SYN_SENT] = TCP_CLOSE,
2924	[TCP_SYN_RECV] = TCP_FIN_WAIT1 | TCP_ACTION_FIN,
2925	[TCP_FIN_WAIT1] = TCP_FIN_WAIT1,
2926	[TCP_FIN_WAIT2] = TCP_FIN_WAIT2,
2927	[TCP_TIME_WAIT] = TCP_CLOSE, /* should not happen ! */
2928	[TCP_CLOSE] = TCP_CLOSE,
2929	[TCP_CLOSE_WAIT] = TCP_LAST_ACK | TCP_ACTION_FIN,
2930	[TCP_LAST_ACK] = TCP_LAST_ACK,
2931	[TCP_LISTEN] = TCP_CLOSE,
2932	[TCP_CLOSING] = TCP_CLOSING,
2933	[TCP_NEW_SYN_RECV] = TCP_CLOSE, /* should not happen ! */
2934	};
2935
2936	static int mptcp_close_state(struct sock *sk)
2937	{
2938	int next = (int)new_state[sk->sk_state];
2939	int ns = next & TCP_STATE_MASK;
2940
2941	mptcp_set_state(sk, state: ns);
2942
2943	return next & TCP_ACTION_FIN;
2944	}
2945
2946	static void mptcp_check_send_data_fin(struct sock *sk)
2947	{
2948	struct mptcp_subflow_context *subflow;
2949	struct mptcp_sock *msk = mptcp_sk(sk);
2950
2951	pr_debug("msk=%p snd_data_fin_enable=%d pending=%d snd_nxt=%llu write_seq=%llu",
2952	msk, msk->snd_data_fin_enable, !!mptcp_send_head(sk),
2953	msk->snd_nxt, msk->write_seq);
2954
2955	/* we still need to enqueue subflows or not really shutting down,
2956	* skip this
2957	*/
2958	if (!msk->snd_data_fin_enable || msk->snd_nxt + 1 != msk->write_seq ||
2959	mptcp_send_head(sk))
2960	return;
2961
2962	WRITE_ONCE(msk->snd_nxt, msk->write_seq);
2963
2964	mptcp_for_each_subflow(msk, subflow) {
2965	struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow);
2966
2967	mptcp_subflow_shutdown(sk, ssk: tcp_sk, SEND_SHUTDOWN);
2968	}
2969	}
2970
2971	static void __mptcp_wr_shutdown(struct sock *sk)
2972	{
2973	struct mptcp_sock *msk = mptcp_sk(sk);
2974
2975	pr_debug("msk=%p snd_data_fin_enable=%d shutdown=%x state=%d pending=%d",
2976	msk, msk->snd_data_fin_enable, sk->sk_shutdown, sk->sk_state,
2977	!!mptcp_send_head(sk));
2978
2979	/* will be ignored by fallback sockets */
2980	WRITE_ONCE(msk->write_seq, msk->write_seq + 1);
2981	WRITE_ONCE(msk->snd_data_fin_enable, 1);
2982
2983	mptcp_check_send_data_fin(sk);
2984	}
2985
2986	static void __mptcp_destroy_sock(struct sock *sk)
2987	{
2988	struct mptcp_sock *msk = mptcp_sk(sk);
2989
2990	pr_debug("msk=%p", msk);
2991
2992	might_sleep();
2993
2994	mptcp_stop_rtx_timer(sk);
2995	sk_stop_timer(sk, timer: &sk->sk_timer);
2996	msk->pm.status = 0;
2997	mptcp_release_sched(msk);
2998
2999	sk->sk_prot->destroy(sk);
3000
3001	WARN_ON_ONCE(READ_ONCE(msk->rmem_fwd_alloc));
3002	WARN_ON_ONCE(msk->rmem_released);
3003	sk_stream_kill_queues(sk);
3004	xfrm_sk_free_policy(sk);
3005
3006	sock_put(sk);
3007	}
3008
3009	void __mptcp_unaccepted_force_close(struct sock *sk)
3010	{
3011	sock_set_flag(sk, flag: SOCK_DEAD);
3012	mptcp_do_fastclose(sk);
3013	__mptcp_destroy_sock(sk);
3014	}
3015
3016	static __poll_t mptcp_check_readable(struct sock *sk)
3017	{
3018	return mptcp_epollin_ready(sk) ? EPOLLIN | EPOLLRDNORM : 0;
3019	}
3020
3021	static void mptcp_check_listen_stop(struct sock *sk)
3022	{
3023	struct sock *ssk;
3024
3025	if (inet_sk_state_load(sk) != TCP_LISTEN)
3026	return;
3027
3028	sock_prot_inuse_add(net: sock_net(sk), prot: sk->sk_prot, val: -1);
3029	ssk = mptcp_sk(sk)->first;
3030	if (WARN_ON_ONCE(!ssk || inet_sk_state_load(ssk) != TCP_LISTEN))
3031	return;
3032
3033	lock_sock_nested(sk: ssk, SINGLE_DEPTH_NESTING);
3034	tcp_set_state(sk: ssk, state: TCP_CLOSE);
3035	mptcp_subflow_queue_clean(sk, ssk);
3036	inet_csk_listen_stop(sk: ssk);
3037	mptcp_event_pm_listener(ssk, event: MPTCP_EVENT_LISTENER_CLOSED);
3038	release_sock(sk: ssk);
3039	}
3040
3041	bool __mptcp_close(struct sock *sk, long timeout)
3042	{
3043	struct mptcp_subflow_context *subflow;
3044	struct mptcp_sock *msk = mptcp_sk(sk);
3045	bool do_cancel_work = false;
3046	int subflows_alive = 0;
3047
3048	WRITE_ONCE(sk->sk_shutdown, SHUTDOWN_MASK);
3049
3050	if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE)) {
3051	mptcp_check_listen_stop(sk);
3052	mptcp_set_state(sk, state: TCP_CLOSE);
3053	goto cleanup;
3054	}
3055
3056	if (mptcp_data_avail(msk) || timeout < 0) {
3057	/* If the msk has read data, or the caller explicitly ask it,
3058	* do the MPTCP equivalent of TCP reset, aka MPTCP fastclose
3059	*/
3060	mptcp_do_fastclose(sk);
3061	timeout = 0;
3062	} else if (mptcp_close_state(sk)) {
3063	__mptcp_wr_shutdown(sk);
3064	}
3065
3066	sk_stream_wait_close(sk, timeo_p: timeout);
3067
3068	cleanup:
3069	/* orphan all the subflows */
3070	mptcp_for_each_subflow(msk, subflow) {
3071	struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
3072	bool slow = lock_sock_fast_nested(sk: ssk);
3073
3074	subflows_alive += ssk->sk_state != TCP_CLOSE;
3075
3076	/* since the close timeout takes precedence on the fail one,
3077	* cancel the latter
3078	*/
3079	if (ssk == msk->first)
3080	subflow->fail_tout = 0;
3081
3082	/* detach from the parent socket, but allow data_ready to
3083	* push incoming data into the mptcp stack, to properly ack it
3084	*/
3085	ssk->sk_socket = NULL;
3086	ssk->sk_wq = NULL;
3087	unlock_sock_fast(sk: ssk, slow);
3088	}
3089	sock_orphan(sk);
3090
3091	/* all the subflows are closed, only timeout can change the msk
3092	* state, let's not keep resources busy for no reasons
3093	*/
3094	if (subflows_alive == 0)
3095	mptcp_set_state(sk, state: TCP_CLOSE);
3096
3097	sock_hold(sk);
3098	pr_debug("msk=%p state=%d", sk, sk->sk_state);
3099	if (msk->token)
3100	mptcp_event(type: MPTCP_EVENT_CLOSED, msk, NULL, GFP_KERNEL);
3101
3102	if (sk->sk_state == TCP_CLOSE) {
3103	__mptcp_destroy_sock(sk);
3104	do_cancel_work = true;
3105	} else {
3106	mptcp_start_tout_timer(sk);
3107	}
3108
3109	return do_cancel_work;
3110	}
3111
3112	static void mptcp_close(struct sock *sk, long timeout)
3113	{
3114	bool do_cancel_work;
3115
3116	lock_sock(sk);
3117
3118	do_cancel_work = __mptcp_close(sk, timeout);
3119	release_sock(sk);
3120	if (do_cancel_work)
3121	mptcp_cancel_work(sk);
3122
3123	sock_put(sk);
3124	}
3125
3126	static void mptcp_copy_inaddrs(struct sock *msk, const struct sock *ssk)
3127	{
3128	#if IS_ENABLED(CONFIG_MPTCP_IPV6)
3129	const struct ipv6_pinfo *ssk6 = inet6_sk(sk: ssk);
3130	struct ipv6_pinfo *msk6 = inet6_sk(sk: msk);
3131
3132	msk->sk_v6_daddr = ssk->sk_v6_daddr;
3133	msk->sk_v6_rcv_saddr = ssk->sk_v6_rcv_saddr;
3134
3135	if (msk6 && ssk6) {
3136	msk6->saddr = ssk6->saddr;
3137	msk6->flow_label = ssk6->flow_label;
3138	}
3139	#endif
3140
3141	inet_sk(msk)->inet_num = inet_sk(ssk)->inet_num;
3142	inet_sk(msk)->inet_dport = inet_sk(ssk)->inet_dport;
3143	inet_sk(msk)->inet_sport = inet_sk(ssk)->inet_sport;
3144	inet_sk(msk)->inet_daddr = inet_sk(ssk)->inet_daddr;
3145	inet_sk(msk)->inet_saddr = inet_sk(ssk)->inet_saddr;
3146	inet_sk(msk)->inet_rcv_saddr = inet_sk(ssk)->inet_rcv_saddr;
3147	}
3148
3149	static int mptcp_disconnect(struct sock *sk, int flags)
3150	{
3151	struct mptcp_sock *msk = mptcp_sk(sk);
3152
3153	/* We are on the fastopen error path. We can't call straight into the
3154	* subflows cleanup code due to lock nesting (we are already under
3155	* msk->firstsocket lock).
3156	*/
3157	if (msk->fastopening)
3158	return -EBUSY;
3159
3160	mptcp_check_listen_stop(sk);
3161	mptcp_set_state(sk, state: TCP_CLOSE);
3162
3163	mptcp_stop_rtx_timer(sk);
3164	mptcp_stop_tout_timer(sk);
3165
3166	if (msk->token)
3167	mptcp_event(type: MPTCP_EVENT_CLOSED, msk, NULL, GFP_KERNEL);
3168
3169	/* msk->subflow is still intact, the following will not free the first
3170	* subflow
3171	*/
3172	mptcp_destroy_common(msk, MPTCP_CF_FASTCLOSE);
3173	WRITE_ONCE(msk->flags, 0);
3174	msk->cb_flags = 0;
3175	msk->recovery = false;
3176	WRITE_ONCE(msk->can_ack, false);
3177	WRITE_ONCE(msk->fully_established, false);
3178	WRITE_ONCE(msk->rcv_data_fin, false);
3179	WRITE_ONCE(msk->snd_data_fin_enable, false);
3180	WRITE_ONCE(msk->rcv_fastclose, false);
3181	WRITE_ONCE(msk->use_64bit_ack, false);
3182	WRITE_ONCE(msk->csum_enabled, mptcp_is_checksum_enabled(sock_net(sk)));
3183	mptcp_pm_data_reset(msk);
3184	mptcp_ca_reset(sk);
3185	msk->bytes_consumed = 0;
3186	msk->bytes_acked = 0;
3187	msk->bytes_received = 0;
3188	msk->bytes_sent = 0;
3189	msk->bytes_retrans = 0;
3190	msk->rcvspace_init = 0;
3191
3192	WRITE_ONCE(sk->sk_shutdown, 0);
3193	sk_error_report(sk);
3194	return 0;
3195	}
3196
3197	#if IS_ENABLED(CONFIG_MPTCP_IPV6)
3198	static struct ipv6_pinfo *mptcp_inet6_sk(const struct sock *sk)
3199	{
3200	unsigned int offset = sizeof(struct mptcp6_sock) - sizeof(struct ipv6_pinfo);
3201
3202	return (struct ipv6_pinfo *)(((u8 *)sk) + offset);
3203	}
3204
3205	static void mptcp_copy_ip6_options(struct sock *newsk, const struct sock *sk)
3206	{
3207	const struct ipv6_pinfo *np = inet6_sk(sk: sk);
3208	struct ipv6_txoptions *opt;
3209	struct ipv6_pinfo *newnp;
3210
3211	newnp = inet6_sk(sk: newsk);
3212
3213	rcu_read_lock();
3214	opt = rcu_dereference(np->opt);
3215	if (opt) {
3216	opt = ipv6_dup_options(sk: newsk, opt);
3217	if (!opt)
3218	net_warn_ratelimited("%s: Failed to copy ip6 options\n", __func__);
3219	}
3220	RCU_INIT_POINTER(newnp->opt, opt);
3221	rcu_read_unlock();
3222	}
3223	#endif
3224
3225	static void mptcp_copy_ip_options(struct sock *newsk, const struct sock *sk)
3226	{
3227	struct ip_options_rcu *inet_opt, *newopt = NULL;
3228	const struct inet_sock *inet = inet_sk(sk);
3229	struct inet_sock *newinet;
3230
3231	newinet = inet_sk(newsk);
3232
3233	rcu_read_lock();
3234	inet_opt = rcu_dereference(inet->inet_opt);
3235	if (inet_opt) {
3236	newopt = sock_kmalloc(sk: newsk, size: sizeof(*inet_opt) +
3237	inet_opt->opt.optlen, GFP_ATOMIC);
3238	if (newopt)
3239	memcpy(newopt, inet_opt, sizeof(*inet_opt) +
3240	inet_opt->opt.optlen);
3241	else
3242	net_warn_ratelimited("%s: Failed to copy ip options\n", __func__);
3243	}
3244	RCU_INIT_POINTER(newinet->inet_opt, newopt);
3245	rcu_read_unlock();
3246	}
3247
3248	struct sock *mptcp_sk_clone_init(const struct sock *sk,
3249	const struct mptcp_options_received *mp_opt,
3250	struct sock *ssk,
3251	struct request_sock *req)
3252	{
3253	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(rsk: req);
3254	struct sock *nsk = sk_clone_lock(sk, GFP_ATOMIC);
3255	struct mptcp_subflow_context *subflow;
3256	struct mptcp_sock *msk;
3257
3258	if (!nsk)
3259	return NULL;
3260
3261	#if IS_ENABLED(CONFIG_MPTCP_IPV6)
3262	if (nsk->sk_family == AF_INET6)
3263	inet_sk(nsk)->pinet6 = mptcp_inet6_sk(sk: nsk);
3264	#endif
3265
3266	__mptcp_init_sock(sk: nsk);
3267
3268	#if IS_ENABLED(CONFIG_MPTCP_IPV6)
3269	if (nsk->sk_family == AF_INET6)
3270	mptcp_copy_ip6_options(newsk: nsk, sk);
3271	else
3272	#endif
3273	mptcp_copy_ip_options(newsk: nsk, sk);
3274
3275	msk = mptcp_sk(nsk);
3276	WRITE_ONCE(msk->local_key, subflow_req->local_key);
3277	WRITE_ONCE(msk->token, subflow_req->token);
3278	msk->in_accept_queue = 1;
3279	WRITE_ONCE(msk->fully_established, false);
3280	if (mp_opt->suboptions & OPTION_MPTCP_CSUMREQD)
3281	WRITE_ONCE(msk->csum_enabled, true);
3282
3283	WRITE_ONCE(msk->write_seq, subflow_req->idsn + 1);
3284	WRITE_ONCE(msk->snd_nxt, msk->write_seq);
3285	WRITE_ONCE(msk->snd_una, msk->write_seq);
3286	WRITE_ONCE(msk->wnd_end, msk->snd_nxt + tcp_sk(ssk)->snd_wnd);
3287	msk->setsockopt_seq = mptcp_sk(sk)->setsockopt_seq;
3288	mptcp_init_sched(msk, mptcp_sk(sk)->sched);
3289
3290	/* passive msk is created after the first/MPC subflow */
3291	msk->subflow_id = 2;
3292
3293	sock_reset_flag(sk: nsk, flag: SOCK_RCU_FREE);
3294	security_inet_csk_clone(newsk: nsk, req);
3295
3296	/* this can't race with mptcp_close(), as the msk is
3297	* not yet exposted to user-space
3298	*/
3299	mptcp_set_state(sk: nsk, state: TCP_ESTABLISHED);
3300
3301	/* The msk maintain a ref to each subflow in the connections list */
3302	WRITE_ONCE(msk->first, ssk);
3303	subflow = mptcp_subflow_ctx(sk: ssk);
3304	list_add(new: &subflow->node, head: &msk->conn_list);
3305	sock_hold(sk: ssk);
3306
3307	/* new mpc subflow takes ownership of the newly
3308	* created mptcp socket
3309	*/
3310	mptcp_token_accept(r: subflow_req, msk);
3311
3312	/* set msk addresses early to ensure mptcp_pm_get_local_id()
3313	* uses the correct data
3314	*/
3315	mptcp_copy_inaddrs(msk: nsk, ssk);
3316	__mptcp_propagate_sndbuf(sk: nsk, ssk);
3317
3318	mptcp_rcv_space_init(msk, ssk);
3319
3320	if (mp_opt->suboptions & OPTION_MPTCP_MPC_ACK)
3321	__mptcp_subflow_fully_established(msk, subflow, mp_opt);
3322	bh_unlock_sock(nsk);
3323
3324	/* note: the newly allocated socket refcount is 2 now */
3325	return nsk;
3326	}
3327
3328	void mptcp_rcv_space_init(struct mptcp_sock *msk, const struct sock *ssk)
3329	{
3330	const struct tcp_sock *tp = tcp_sk(ssk);
3331
3332	msk->rcvspace_init = 1;
3333	msk->rcvq_space.copied = 0;
3334	msk->rcvq_space.rtt_us = 0;
3335
3336	msk->rcvq_space.time = tp->tcp_mstamp;
3337
3338	/* initial rcv_space offering made to peer */
3339	msk->rcvq_space.space = min_t(u32, tp->rcv_wnd,
3340	TCP_INIT_CWND * tp->advmss);
3341	if (msk->rcvq_space.space == 0)
3342	msk->rcvq_space.space = TCP_INIT_CWND * TCP_MSS_DEFAULT;
3343	}
3344
3345	void mptcp_destroy_common(struct mptcp_sock *msk, unsigned int flags)
3346	{
3347	struct mptcp_subflow_context *subflow, *tmp;
3348	struct sock *sk = (struct sock *)msk;
3349
3350	__mptcp_clear_xmit(sk);
3351
3352	/* join list will be eventually flushed (with rst) at sock lock release time */
3353	mptcp_for_each_subflow_safe(msk, subflow, tmp)
3354	__mptcp_close_ssk(sk, ssk: mptcp_subflow_tcp_sock(subflow), subflow, flags);
3355
3356	/* move to sk_receive_queue, sk_stream_kill_queues will purge it */
3357	mptcp_data_lock(sk);
3358	skb_queue_splice_tail_init(list: &msk->receive_queue, head: &sk->sk_receive_queue);
3359	__skb_queue_purge(list: &sk->sk_receive_queue);
3360	skb_rbtree_purge(root: &msk->out_of_order_queue);
3361	mptcp_data_unlock(sk);
3362
3363	/* move all the rx fwd alloc into the sk_mem_reclaim_final in
3364	* inet_sock_destruct() will dispose it
3365	*/
3366	sk_forward_alloc_add(sk, val: msk->rmem_fwd_alloc);
3367	WRITE_ONCE(msk->rmem_fwd_alloc, 0);
3368	mptcp_token_destroy(msk);
3369	mptcp_pm_free_anno_list(msk);
3370	mptcp_free_local_addr_list(msk);
3371	}
3372
3373	static void mptcp_destroy(struct sock *sk)
3374	{
3375	struct mptcp_sock *msk = mptcp_sk(sk);
3376
3377	/* allow the following to close even the initial subflow */
3378	msk->free_first = 1;
3379	mptcp_destroy_common(msk, flags: 0);
3380	sk_sockets_allocated_dec(sk);
3381	}
3382
3383	void __mptcp_data_acked(struct sock *sk)
3384	{
3385	if (!sock_owned_by_user(sk))
3386	__mptcp_clean_una(sk);
3387	else
3388	__set_bit(MPTCP_CLEAN_UNA, &mptcp_sk(sk)->cb_flags);
3389	}
3390
3391	void __mptcp_check_push(struct sock *sk, struct sock *ssk)
3392	{
3393	if (!mptcp_send_head(sk))
3394	return;
3395
3396	if (!sock_owned_by_user(sk))
3397	__mptcp_subflow_push_pending(sk, ssk, first: false);
3398	else
3399	__set_bit(MPTCP_PUSH_PENDING, &mptcp_sk(sk)->cb_flags);
3400	}
3401
3402	#define MPTCP_FLAGS_PROCESS_CTX_NEED (BIT(MPTCP_PUSH_PENDING) | \
3403	BIT(MPTCP_RETRANSMIT) | \
3404	BIT(MPTCP_FLUSH_JOIN_LIST))
3405
3406	/* processes deferred events and flush wmem */
3407	static void mptcp_release_cb(struct sock *sk)
3408	__must_hold(&sk->sk_lock.slock)
3409	{
3410	struct mptcp_sock *msk = mptcp_sk(sk);
3411
3412	for (;;) {
3413	unsigned long flags = (msk->cb_flags & MPTCP_FLAGS_PROCESS_CTX_NEED);
3414	struct list_head join_list;
3415
3416	if (!flags)
3417	break;
3418
3419	INIT_LIST_HEAD(list: &join_list);
3420	list_splice_init(list: &msk->join_list, head: &join_list);
3421
3422	/* the following actions acquire the subflow socket lock
3423	*
3424	* 1) can't be invoked in atomic scope
3425	* 2) must avoid ABBA deadlock with msk socket spinlock: the RX
3426	* datapath acquires the msk socket spinlock while helding
3427	* the subflow socket lock
3428	*/
3429	msk->cb_flags &= ~flags;
3430	spin_unlock_bh(lock: &sk->sk_lock.slock);
3431
3432	if (flags & BIT(MPTCP_FLUSH_JOIN_LIST))
3433	__mptcp_flush_join_list(sk, join_list: &join_list);
3434	if (flags & BIT(MPTCP_PUSH_PENDING))
3435	__mptcp_push_pending(sk, flags: 0);
3436	if (flags & BIT(MPTCP_RETRANSMIT))
3437	__mptcp_retrans(sk);
3438
3439	cond_resched();
3440	spin_lock_bh(lock: &sk->sk_lock.slock);
3441	}
3442
3443	if (__test_and_clear_bit(MPTCP_CLEAN_UNA, &msk->cb_flags))
3444	__mptcp_clean_una_wakeup(sk);
3445	if (unlikely(msk->cb_flags)) {
3446	/* be sure to sync the msk state before taking actions
3447	* depending on sk_state (MPTCP_ERROR_REPORT)
3448	* On sk release avoid actions depending on the first subflow
3449	*/
3450	if (__test_and_clear_bit(MPTCP_SYNC_STATE, &msk->cb_flags) && msk->first)
3451	__mptcp_sync_state(sk, state: msk->pending_state);
3452	if (__test_and_clear_bit(MPTCP_ERROR_REPORT, &msk->cb_flags))
3453	__mptcp_error_report(sk);
3454	if (__test_and_clear_bit(MPTCP_SYNC_SNDBUF, &msk->cb_flags))
3455	__mptcp_sync_sndbuf(sk);
3456	}
3457
3458	__mptcp_update_rmem(sk);
3459	}
3460
3461	/* MP_JOIN client subflow must wait for 4th ack before sending any data:
3462	* TCP can't schedule delack timer before the subflow is fully established.
3463	* MPTCP uses the delack timer to do 3rd ack retransmissions
3464	*/
3465	static void schedule_3rdack_retransmission(struct sock *ssk)
3466	{
3467	struct inet_connection_sock *icsk = inet_csk(sk: ssk);
3468	struct tcp_sock *tp = tcp_sk(ssk);
3469	unsigned long timeout;
3470
3471	if (mptcp_subflow_ctx(sk: ssk)->fully_established)
3472	return;
3473
3474	/* reschedule with a timeout above RTT, as we must look only for drop */
3475	if (tp->srtt_us)
3476	timeout = usecs_to_jiffies(u: tp->srtt_us >> (3 - 1));
3477	else
3478	timeout = TCP_TIMEOUT_INIT;
3479	timeout += jiffies;
3480
3481	WARN_ON_ONCE(icsk->icsk_ack.pending & ICSK_ACK_TIMER);
3482	icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
3483	icsk->icsk_ack.timeout = timeout;
3484	sk_reset_timer(sk: ssk, timer: &icsk->icsk_delack_timer, expires: timeout);
3485	}
3486
3487	void mptcp_subflow_process_delegated(struct sock *ssk, long status)
3488	{
3489	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk: ssk);
3490	struct sock *sk = subflow->conn;
3491
3492	if (status & BIT(MPTCP_DELEGATE_SEND)) {
3493	mptcp_data_lock(sk);
3494	if (!sock_owned_by_user(sk))
3495	__mptcp_subflow_push_pending(sk, ssk, first: true);
3496	else
3497	__set_bit(MPTCP_PUSH_PENDING, &mptcp_sk(sk)->cb_flags);
3498	mptcp_data_unlock(sk);
3499	}
3500	if (status & BIT(MPTCP_DELEGATE_SNDBUF)) {
3501	mptcp_data_lock(sk);
3502	if (!sock_owned_by_user(sk))
3503	__mptcp_sync_sndbuf(sk);
3504	else
3505	__set_bit(MPTCP_SYNC_SNDBUF, &mptcp_sk(sk)->cb_flags);
3506	mptcp_data_unlock(sk);
3507	}
3508	if (status & BIT(MPTCP_DELEGATE_ACK))
3509	schedule_3rdack_retransmission(ssk);
3510	}
3511
3512	static int mptcp_hash(struct sock *sk)
3513	{
3514	/* should never be called,
3515	* we hash the TCP subflows not the master socket
3516	*/
3517	WARN_ON_ONCE(1);
3518	return 0;
3519	}
3520
3521	static void mptcp_unhash(struct sock *sk)
3522	{
3523	/* called from sk_common_release(), but nothing to do here */
3524	}
3525
3526	static int mptcp_get_port(struct sock *sk, unsigned short snum)
3527	{
3528	struct mptcp_sock *msk = mptcp_sk(sk);
3529
3530	pr_debug("msk=%p, ssk=%p", msk, msk->first);
3531	if (WARN_ON_ONCE(!msk->first))
3532	return -EINVAL;
3533
3534	return inet_csk_get_port(sk: msk->first, snum);
3535	}
3536
3537	void mptcp_finish_connect(struct sock *ssk)
3538	{
3539	struct mptcp_subflow_context *subflow;
3540	struct mptcp_sock *msk;
3541	struct sock *sk;
3542
3543	subflow = mptcp_subflow_ctx(sk: ssk);
3544	sk = subflow->conn;
3545	msk = mptcp_sk(sk);
3546
3547	pr_debug("msk=%p, token=%u", sk, subflow->token);
3548
3549	subflow->map_seq = subflow->iasn;
3550	subflow->map_subflow_seq = 1;
3551
3552	/* the socket is not connected yet, no msk/subflow ops can access/race
3553	* accessing the field below
3554	*/
3555	WRITE_ONCE(msk->local_key, subflow->local_key);
3556
3557	mptcp_pm_new_connection(msk, ssk, server_side: 0);
3558	}
3559
3560	void mptcp_sock_graft(struct sock *sk, struct socket *parent)
3561	{
3562	write_lock_bh(&sk->sk_callback_lock);
3563	rcu_assign_pointer(sk->sk_wq, &parent->wq);
3564	sk_set_socket(sk, sock: parent);
3565	sk->sk_uid = SOCK_INODE(socket: parent)->i_uid;
3566	write_unlock_bh(&sk->sk_callback_lock);
3567	}
3568
3569	bool mptcp_finish_join(struct sock *ssk)
3570	{
3571	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk: ssk);
3572	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
3573	struct sock *parent = (void *)msk;
3574	bool ret = true;
3575
3576	pr_debug("msk=%p, subflow=%p", msk, subflow);
3577
3578	/* mptcp socket already closing? */
3579	if (!mptcp_is_fully_established(sk: parent)) {
3580	subflow->reset_reason = MPTCP_RST_EMPTCP;
3581	return false;
3582	}
3583
3584	/* active subflow, already present inside the conn_list */
3585	if (!list_empty(head: &subflow->node)) {
3586	mptcp_subflow_joined(msk, ssk);
3587	mptcp_propagate_sndbuf(sk: parent, ssk);
3588	return true;
3589	}
3590
3591	if (!mptcp_pm_allow_new_subflow(msk))
3592	goto err_prohibited;
3593
3594	/* If we can't acquire msk socket lock here, let the release callback
3595	* handle it
3596	*/
3597	mptcp_data_lock(parent);
3598	if (!sock_owned_by_user(sk: parent)) {
3599	ret = __mptcp_finish_join(msk, ssk);
3600	if (ret) {
3601	sock_hold(sk: ssk);
3602	list_add_tail(new: &subflow->node, head: &msk->conn_list);
3603	}
3604	} else {
3605	sock_hold(sk: ssk);
3606	list_add_tail(new: &subflow->node, head: &msk->join_list);
3607	__set_bit(MPTCP_FLUSH_JOIN_LIST, &msk->cb_flags);
3608	}
3609	mptcp_data_unlock(parent);
3610
3611	if (!ret) {
3612	err_prohibited:
3613	subflow->reset_reason = MPTCP_RST_EPROHIBIT;
3614	return false;
3615	}
3616
3617	return true;
3618	}
3619
3620	static void mptcp_shutdown(struct sock *sk, int how)
3621	{
3622	pr_debug("sk=%p, how=%d", sk, how);
3623
3624	if ((how & SEND_SHUTDOWN) && mptcp_close_state(sk))
3625	__mptcp_wr_shutdown(sk);
3626	}
3627
3628	static int mptcp_forward_alloc_get(const struct sock *sk)
3629	{
3630	return READ_ONCE(sk->sk_forward_alloc) +
3631	READ_ONCE(mptcp_sk(sk)->rmem_fwd_alloc);
3632	}
3633
3634	static int mptcp_ioctl_outq(const struct mptcp_sock *msk, u64 v)
3635	{
3636	const struct sock *sk = (void *)msk;
3637	u64 delta;
3638
3639	if (sk->sk_state == TCP_LISTEN)
3640	return -EINVAL;
3641
3642	if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
3643	return 0;
3644
3645	delta = msk->write_seq - v;
3646	if (__mptcp_check_fallback(msk) && msk->first) {
3647	struct tcp_sock *tp = tcp_sk(msk->first);
3648
3649	/* the first subflow is disconnected after close - see
3650	* __mptcp_close_ssk(). tcp_disconnect() moves the write_seq
3651	* so ignore that status, too.
3652	*/
3653	if (!((1 << msk->first->sk_state) &
3654	(TCPF_SYN_SENT | TCPF_SYN_RECV | TCPF_CLOSE)))
3655	delta += READ_ONCE(tp->write_seq) - tp->snd_una;
3656	}
3657	if (delta > INT_MAX)
3658	delta = INT_MAX;
3659
3660	return (int)delta;
3661	}
3662
3663	static int mptcp_ioctl(struct sock *sk, int cmd, int *karg)
3664	{
3665	struct mptcp_sock *msk = mptcp_sk(sk);
3666	bool slow;
3667
3668	switch (cmd) {
3669	case SIOCINQ:
3670	if (sk->sk_state == TCP_LISTEN)
3671	return -EINVAL;
3672
3673	lock_sock(sk);
3674	__mptcp_move_skbs(msk);
3675	*karg = mptcp_inq_hint(sk);
3676	release_sock(sk);
3677	break;
3678	case SIOCOUTQ:
3679	slow = lock_sock_fast(sk);
3680	*karg = mptcp_ioctl_outq(msk, READ_ONCE(msk->snd_una));
3681	unlock_sock_fast(sk, slow);
3682	break;
3683	case SIOCOUTQNSD:
3684	slow = lock_sock_fast(sk);
3685	*karg = mptcp_ioctl_outq(msk, v: msk->snd_nxt);
3686	unlock_sock_fast(sk, slow);
3687	break;
3688	default:
3689	return -ENOIOCTLCMD;
3690	}
3691
3692	return 0;
3693	}
3694
3695	static void mptcp_subflow_early_fallback(struct mptcp_sock *msk,
3696	struct mptcp_subflow_context *subflow)
3697	{
3698	subflow->request_mptcp = 0;
3699	__mptcp_do_fallback(msk);
3700	}
3701
3702	static int mptcp_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
3703	{
3704	struct mptcp_subflow_context *subflow;
3705	struct mptcp_sock *msk = mptcp_sk(sk);
3706	int err = -EINVAL;
3707	struct sock *ssk;
3708
3709	ssk = __mptcp_nmpc_sk(msk);
3710	if (IS_ERR(ptr: ssk))
3711	return PTR_ERR(ptr: ssk);
3712
3713	mptcp_set_state(sk, state: TCP_SYN_SENT);
3714	subflow = mptcp_subflow_ctx(sk: ssk);
3715	#ifdef CONFIG_TCP_MD5SIG
3716	/* no MPTCP if MD5SIG is enabled on this socket or we may run out of
3717	* TCP option space.
3718	*/
3719	if (rcu_access_pointer(tcp_sk(ssk)->md5sig_info))
3720	mptcp_subflow_early_fallback(msk, subflow);
3721	#endif
3722	if (subflow->request_mptcp && mptcp_token_new_connect(ssk)) {
3723	MPTCP_INC_STATS(net: sock_net(sk: ssk), field: MPTCP_MIB_TOKENFALLBACKINIT);
3724	mptcp_subflow_early_fallback(msk, subflow);
3725	}
3726	if (likely(!__mptcp_check_fallback(msk)))
3727	MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_MPCAPABLEACTIVE);
3728
3729	/* if reaching here via the fastopen/sendmsg path, the caller already
3730	* acquired the subflow socket lock, too.
3731	*/
3732	if (!msk->fastopening)
3733	lock_sock(sk: ssk);
3734
3735	/* the following mirrors closely a very small chunk of code from
3736	* __inet_stream_connect()
3737	*/
3738	if (ssk->sk_state != TCP_CLOSE)
3739	goto out;
3740
3741	if (BPF_CGROUP_PRE_CONNECT_ENABLED(ssk)) {
3742	err = ssk->sk_prot->pre_connect(ssk, uaddr, addr_len);
3743	if (err)
3744	goto out;
3745	}
3746
3747	err = ssk->sk_prot->connect(ssk, uaddr, addr_len);
3748	if (err < 0)
3749	goto out;
3750
3751	inet_assign_bit(DEFER_CONNECT, sk, inet_test_bit(DEFER_CONNECT, ssk));
3752
3753	out:
3754	if (!msk->fastopening)
3755	release_sock(sk: ssk);
3756
3757	/* on successful connect, the msk state will be moved to established by
3758	* subflow_finish_connect()
3759	*/
3760	if (unlikely(err)) {
3761	/* avoid leaving a dangling token in an unconnected socket */
3762	mptcp_token_destroy(msk);
3763	mptcp_set_state(sk, state: TCP_CLOSE);
3764	return err;
3765	}
3766
3767	mptcp_copy_inaddrs(msk: sk, ssk);
3768	return 0;
3769	}
3770
3771	static struct proto mptcp_prot = {
3772	.name = "MPTCP",
3773	.owner = THIS_MODULE,
3774	.init = mptcp_init_sock,
3775	.connect = mptcp_connect,
3776	.disconnect = mptcp_disconnect,
3777	.close = mptcp_close,
3778	.setsockopt = mptcp_setsockopt,
3779	.getsockopt = mptcp_getsockopt,
3780	.shutdown = mptcp_shutdown,
3781	.destroy = mptcp_destroy,
3782	.sendmsg = mptcp_sendmsg,
3783	.ioctl = mptcp_ioctl,
3784	.recvmsg = mptcp_recvmsg,
3785	.release_cb = mptcp_release_cb,
3786	.hash = mptcp_hash,
3787	.unhash = mptcp_unhash,
3788	.get_port = mptcp_get_port,
3789	.forward_alloc_get = mptcp_forward_alloc_get,
3790	.stream_memory_free = mptcp_stream_memory_free,
3791	.sockets_allocated = &mptcp_sockets_allocated,
3792
3793	.memory_allocated = &tcp_memory_allocated,
3794	.per_cpu_fw_alloc = &tcp_memory_per_cpu_fw_alloc,
3795
3796	.memory_pressure = &tcp_memory_pressure,
3797	.sysctl_wmem_offset = offsetof(struct net, ipv4.sysctl_tcp_wmem),
3798	.sysctl_rmem_offset = offsetof(struct net, ipv4.sysctl_tcp_rmem),
3799	.sysctl_mem = sysctl_tcp_mem,
3800	.obj_size = sizeof(struct mptcp_sock),
3801	.slab_flags = SLAB_TYPESAFE_BY_RCU,
3802	.no_autobind = true,
3803	};
3804
3805	static int mptcp_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
3806	{
3807	struct mptcp_sock *msk = mptcp_sk(sock->sk);
3808	struct sock *ssk, *sk = sock->sk;
3809	int err = -EINVAL;
3810
3811	lock_sock(sk);
3812	ssk = __mptcp_nmpc_sk(msk);
3813	if (IS_ERR(ptr: ssk)) {
3814	err = PTR_ERR(ptr: ssk);
3815	goto unlock;
3816	}
3817
3818	if (sk->sk_family == AF_INET)
3819	err = inet_bind_sk(sk: ssk, uaddr, addr_len);
3820	#if IS_ENABLED(CONFIG_MPTCP_IPV6)
3821	else if (sk->sk_family == AF_INET6)
3822	err = inet6_bind_sk(sk: ssk, uaddr, addr_len);
3823	#endif
3824	if (!err)
3825	mptcp_copy_inaddrs(msk: sk, ssk);
3826
3827	unlock:
3828	release_sock(sk);
3829	return err;
3830	}
3831
3832	static int mptcp_listen(struct socket *sock, int backlog)
3833	{
3834	struct mptcp_sock *msk = mptcp_sk(sock->sk);
3835	struct sock *sk = sock->sk;
3836	struct sock *ssk;
3837	int err;
3838
3839	pr_debug("msk=%p", msk);
3840
3841	lock_sock(sk);
3842
3843	err = -EINVAL;
3844	if (sock->state != SS_UNCONNECTED || sock->type != SOCK_STREAM)
3845	goto unlock;
3846
3847	ssk = __mptcp_nmpc_sk(msk);
3848	if (IS_ERR(ptr: ssk)) {
3849	err = PTR_ERR(ptr: ssk);
3850	goto unlock;
3851	}
3852
3853	mptcp_set_state(sk, state: TCP_LISTEN);
3854	sock_set_flag(sk, flag: SOCK_RCU_FREE);
3855
3856	lock_sock(sk: ssk);
3857	err = __inet_listen_sk(sk: ssk, backlog);
3858	release_sock(sk: ssk);
3859	mptcp_set_state(sk, state: inet_sk_state_load(sk: ssk));
3860
3861	if (!err) {
3862	sock_prot_inuse_add(net: sock_net(sk), prot: sk->sk_prot, val: 1);
3863	mptcp_copy_inaddrs(msk: sk, ssk);
3864	mptcp_event_pm_listener(ssk, event: MPTCP_EVENT_LISTENER_CREATED);
3865	}
3866
3867	unlock:
3868	release_sock(sk);
3869	return err;
3870	}
3871
3872	static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
3873	int flags, bool kern)
3874	{
3875	struct mptcp_sock *msk = mptcp_sk(sock->sk);
3876	struct sock *ssk, *newsk;
3877	int err;
3878
3879	pr_debug("msk=%p", msk);
3880
3881	/* Buggy applications can call accept on socket states other then LISTEN
3882	* but no need to allocate the first subflow just to error out.
3883	*/
3884	ssk = READ_ONCE(msk->first);
3885	if (!ssk)
3886	return -EINVAL;
3887
3888	pr_debug("ssk=%p, listener=%p", ssk, mptcp_subflow_ctx(ssk));
3889	newsk = inet_csk_accept(sk: ssk, flags, err: &err, kern);
3890	if (!newsk)
3891	return err;
3892
3893	pr_debug("newsk=%p, subflow is mptcp=%d", newsk, sk_is_mptcp(newsk));
3894	if (sk_is_mptcp(sk: newsk)) {
3895	struct mptcp_subflow_context *subflow;
3896	struct sock *new_mptcp_sock;
3897
3898	subflow = mptcp_subflow_ctx(sk: newsk);
3899	new_mptcp_sock = subflow->conn;
3900
3901	/* is_mptcp should be false if subflow->conn is missing, see
3902	* subflow_syn_recv_sock()
3903	*/
3904	if (WARN_ON_ONCE(!new_mptcp_sock)) {
3905	tcp_sk(newsk)->is_mptcp = 0;
3906	goto tcpfallback;
3907	}
3908
3909	newsk = new_mptcp_sock;
3910	MPTCP_INC_STATS(net: sock_net(sk: ssk), field: MPTCP_MIB_MPCAPABLEPASSIVEACK);
3911
3912	newsk->sk_kern_sock = kern;
3913	lock_sock(sk: newsk);
3914	__inet_accept(sock, newsock, newsk);
3915
3916	set_bit(SOCK_CUSTOM_SOCKOPT, addr: &newsock->flags);
3917	msk = mptcp_sk(newsk);
3918	msk->in_accept_queue = 0;
3919
3920	/* set ssk->sk_socket of accept()ed flows to mptcp socket.
3921	* This is needed so NOSPACE flag can be set from tcp stack.
3922	*/
3923	mptcp_for_each_subflow(msk, subflow) {
3924	struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
3925
3926	if (!ssk->sk_socket)
3927	mptcp_sock_graft(sk: ssk, parent: newsock);
3928	}
3929
3930	/* Do late cleanup for the first subflow as necessary. Also
3931	* deal with bad peers not doing a complete shutdown.
3932	*/
3933	if (unlikely(inet_sk_state_load(msk->first) == TCP_CLOSE)) {
3934	__mptcp_close_ssk(sk: newsk, ssk: msk->first,
3935	subflow: mptcp_subflow_ctx(sk: msk->first), flags: 0);
3936	if (unlikely(list_is_singular(&msk->conn_list)))
3937	mptcp_set_state(sk: newsk, state: TCP_CLOSE);
3938	}
3939	} else {
3940	tcpfallback:
3941	newsk->sk_kern_sock = kern;
3942	lock_sock(sk: newsk);
3943	__inet_accept(sock, newsock, newsk);
3944	/* we are being invoked after accepting a non-mp-capable
3945	* flow: sk is a tcp_sk, not an mptcp one.
3946	*
3947	* Hand the socket over to tcp so all further socket ops
3948	* bypass mptcp.
3949	*/
3950	WRITE_ONCE(newsock->sk->sk_socket->ops,
3951	mptcp_fallback_tcp_ops(newsock->sk));
3952	}
3953	release_sock(sk: newsk);
3954
3955	return 0;
3956	}
3957
3958	static __poll_t mptcp_check_writeable(struct mptcp_sock *msk)
3959	{
3960	struct sock *sk = (struct sock *)msk;
3961
3962	if (__mptcp_stream_is_writeable(sk, wake: 1))
3963	return EPOLLOUT | EPOLLWRNORM;
3964
3965	set_bit(SOCK_NOSPACE, addr: &sk->sk_socket->flags);
3966	smp_mb__after_atomic(); /* NOSPACE is changed by mptcp_write_space() */
3967	if (__mptcp_stream_is_writeable(sk, wake: 1))
3968	return EPOLLOUT | EPOLLWRNORM;
3969
3970	return 0;
3971	}
3972
3973	static __poll_t mptcp_poll(struct file *file, struct socket *sock,
3974	struct poll_table_struct *wait)
3975	{
3976	struct sock *sk = sock->sk;
3977	struct mptcp_sock *msk;
3978	__poll_t mask = 0;
3979	u8 shutdown;
3980	int state;
3981
3982	msk = mptcp_sk(sk);
3983	sock_poll_wait(filp: file, sock, p: wait);
3984
3985	state = inet_sk_state_load(sk);
3986	pr_debug("msk=%p state=%d flags=%lx", msk, state, msk->flags);
3987	if (state == TCP_LISTEN) {
3988	struct sock *ssk = READ_ONCE(msk->first);
3989
3990	if (WARN_ON_ONCE(!ssk))
3991	return 0;
3992
3993	return inet_csk_listen_poll(sk: ssk);
3994	}
3995
3996	shutdown = READ_ONCE(sk->sk_shutdown);
3997	if (shutdown == SHUTDOWN_MASK || state == TCP_CLOSE)
3998	mask |= EPOLLHUP;
3999	if (shutdown & RCV_SHUTDOWN)
4000	mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP;
4001
4002	if (state != TCP_SYN_SENT && state != TCP_SYN_RECV) {
4003	mask |= mptcp_check_readable(sk);
4004	if (shutdown & SEND_SHUTDOWN)
4005	mask |= EPOLLOUT | EPOLLWRNORM;
4006	else
4007	mask |= mptcp_check_writeable(msk);
4008	} else if (state == TCP_SYN_SENT &&
4009	inet_test_bit(DEFER_CONNECT, sk)) {
4010	/* cf tcp_poll() note about TFO */
4011	mask |= EPOLLOUT | EPOLLWRNORM;
4012	}
4013
4014	/* This barrier is coupled with smp_wmb() in __mptcp_error_report() */
4015	smp_rmb();
4016	if (READ_ONCE(sk->sk_err))
4017	mask |= EPOLLERR;
4018
4019	return mask;
4020	}
4021
4022	static const struct proto_ops mptcp_stream_ops = {
4023	.family = PF_INET,
4024	.owner = THIS_MODULE,
4025	.release = inet_release,
4026	.bind = mptcp_bind,
4027	.connect = inet_stream_connect,
4028	.socketpair = sock_no_socketpair,
4029	.accept = mptcp_stream_accept,
4030	.getname = inet_getname,
4031	.poll = mptcp_poll,
4032	.ioctl = inet_ioctl,
4033	.gettstamp = sock_gettstamp,
4034	.listen = mptcp_listen,
4035	.shutdown = inet_shutdown,
4036	.setsockopt = sock_common_setsockopt,
4037	.getsockopt = sock_common_getsockopt,
4038	.sendmsg = inet_sendmsg,
4039	.recvmsg = inet_recvmsg,
4040	.mmap = sock_no_mmap,
4041	.set_rcvlowat = mptcp_set_rcvlowat,
4042	};
4043
4044	static struct inet_protosw mptcp_protosw = {
4045	.type = SOCK_STREAM,
4046	.protocol = IPPROTO_MPTCP,
4047	.prot = &mptcp_prot,
4048	.ops = &mptcp_stream_ops,
4049	.flags = INET_PROTOSW_ICSK,
4050	};
4051
4052	static int mptcp_napi_poll(struct napi_struct *napi, int budget)
4053	{
4054	struct mptcp_delegated_action *delegated;
4055	struct mptcp_subflow_context *subflow;
4056	int work_done = 0;
4057
4058	delegated = container_of(napi, struct mptcp_delegated_action, napi);
4059	while ((subflow = mptcp_subflow_delegated_next(delegated)) != NULL) {
4060	struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
4061
4062	bh_lock_sock_nested(ssk);
4063	if (!sock_owned_by_user(sk: ssk)) {
4064	mptcp_subflow_process_delegated(ssk, xchg(&subflow->delegated_status, 0));
4065	} else {
4066	/* tcp_release_cb_override already processed
4067	* the action or will do at next release_sock().
4068	* In both case must dequeue the subflow here - on the same
4069	* CPU that scheduled it.
4070	*/
4071	smp_wmb();
4072	clear_bit(MPTCP_DELEGATE_SCHEDULED, addr: &subflow->delegated_status);
4073	}
4074	bh_unlock_sock(ssk);
4075	sock_put(sk: ssk);
4076
4077	if (++work_done == budget)
4078	return budget;
4079	}
4080
4081	/* always provide a 0 'work_done' argument, so that napi_complete_done
4082	* will not try accessing the NULL napi->dev ptr
4083	*/
4084	napi_complete_done(n: napi, work_done: 0);
4085	return work_done;
4086	}
4087
4088	void __init mptcp_proto_init(void)
4089	{
4090	struct mptcp_delegated_action *delegated;
4091	int cpu;
4092
4093	mptcp_prot.h.hashinfo = tcp_prot.h.hashinfo;
4094
4095	if (percpu_counter_init(&mptcp_sockets_allocated, 0, GFP_KERNEL))
4096	panic(fmt: "Failed to allocate MPTCP pcpu counter\n");
4097
4098	init_dummy_netdev(dev: &mptcp_napi_dev);
4099	for_each_possible_cpu(cpu) {
4100	delegated = per_cpu_ptr(&mptcp_delegated_actions, cpu);
4101	INIT_LIST_HEAD(list: &delegated->head);
4102	netif_napi_add_tx(dev: &mptcp_napi_dev, napi: &delegated->napi,
4103	poll: mptcp_napi_poll);
4104	napi_enable(n: &delegated->napi);
4105	}
4106
4107	mptcp_subflow_init();
4108	mptcp_pm_init();
4109	mptcp_sched_init();
4110	mptcp_token_init();
4111
4112	if (proto_register(prot: &mptcp_prot, alloc_slab: 1) != 0)
4113	panic(fmt: "Failed to register MPTCP proto.\n");
4114
4115	inet_register_protosw(p: &mptcp_protosw);
4116
4117	BUILD_BUG_ON(sizeof(struct mptcp_skb_cb) > sizeof_field(struct sk_buff, cb));
4118	}
4119
4120	#if IS_ENABLED(CONFIG_MPTCP_IPV6)
4121	static const struct proto_ops mptcp_v6_stream_ops = {
4122	.family = PF_INET6,
4123	.owner = THIS_MODULE,
4124	.release = inet6_release,
4125	.bind = mptcp_bind,
4126	.connect = inet_stream_connect,
4127	.socketpair = sock_no_socketpair,
4128	.accept = mptcp_stream_accept,
4129	.getname = inet6_getname,
4130	.poll = mptcp_poll,
4131	.ioctl = inet6_ioctl,
4132	.gettstamp = sock_gettstamp,
4133	.listen = mptcp_listen,
4134	.shutdown = inet_shutdown,
4135	.setsockopt = sock_common_setsockopt,
4136	.getsockopt = sock_common_getsockopt,
4137	.sendmsg = inet6_sendmsg,
4138	.recvmsg = inet6_recvmsg,
4139	.mmap = sock_no_mmap,
4140	#ifdef CONFIG_COMPAT
4141	.compat_ioctl = inet6_compat_ioctl,
4142	#endif
4143	.set_rcvlowat = mptcp_set_rcvlowat,
4144	};
4145
4146	static struct proto mptcp_v6_prot;
4147
4148	static struct inet_protosw mptcp_v6_protosw = {
4149	.type = SOCK_STREAM,
4150	.protocol = IPPROTO_MPTCP,
4151	.prot = &mptcp_v6_prot,
4152	.ops = &mptcp_v6_stream_ops,
4153	.flags = INET_PROTOSW_ICSK,
4154	};
4155
4156	int __init mptcp_proto_v6_init(void)
4157	{
4158	int err;
4159
4160	mptcp_v6_prot = mptcp_prot;
4161	strcpy(p: mptcp_v6_prot.name, q: "MPTCPv6");
4162	mptcp_v6_prot.slab = NULL;
4163	mptcp_v6_prot.obj_size = sizeof(struct mptcp6_sock);
4164	mptcp_v6_prot.ipv6_pinfo_offset = offsetof(struct mptcp6_sock, np);
4165
4166	err = proto_register(prot: &mptcp_v6_prot, alloc_slab: 1);
4167	if (err)
4168	return err;
4169
4170	err = inet6_register_protosw(p: &mptcp_v6_protosw);
4171	if (err)
4172	proto_unregister(prot: &mptcp_v6_prot);
4173
4174	return err;
4175	}
4176	#endif
4177