xref: /linux/net/mptcp/protocol.c (revision c2933b2befe25309f4c5cfbea0ca80909735fd76)
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/hotdata.h>
24 #include <net/xfrm.h>
25 #include <asm/ioctls.h>
26 #include "protocol.h"
27 #include "mib.h"
28 
29 #define CREATE_TRACE_POINTS
30 #include <trace/events/mptcp.h>
31 
32 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
33 struct mptcp6_sock {
34 	struct mptcp_sock msk;
35 	struct ipv6_pinfo np;
36 };
37 #endif
38 
39 enum {
40 	MPTCP_CMSG_TS = BIT(0),
41 	MPTCP_CMSG_INQ = BIT(1),
42 };
43 
44 static struct percpu_counter mptcp_sockets_allocated ____cacheline_aligned_in_smp;
45 
46 static void __mptcp_destroy_sock(struct sock *sk);
47 static void mptcp_check_send_data_fin(struct sock *sk);
48 
49 DEFINE_PER_CPU(struct mptcp_delegated_action, mptcp_delegated_actions);
50 static struct net_device *mptcp_napi_dev;
51 
52 /* Returns end sequence number of the receiver's advertised window */
mptcp_wnd_end(const struct mptcp_sock * msk)53 static u64 mptcp_wnd_end(const struct mptcp_sock *msk)
54 {
55 	return READ_ONCE(msk->wnd_end);
56 }
57 
mptcp_fallback_tcp_ops(const struct sock * sk)58 static const struct proto_ops *mptcp_fallback_tcp_ops(const struct sock *sk)
59 {
60 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
61 	if (sk->sk_prot == &tcpv6_prot)
62 		return &inet6_stream_ops;
63 #endif
64 	WARN_ON_ONCE(sk->sk_prot != &tcp_prot);
65 	return &inet_stream_ops;
66 }
67 
__mptcp_socket_create(struct mptcp_sock * msk)68 static int __mptcp_socket_create(struct mptcp_sock *msk)
69 {
70 	struct mptcp_subflow_context *subflow;
71 	struct sock *sk = (struct sock *)msk;
72 	struct socket *ssock;
73 	int err;
74 
75 	err = mptcp_subflow_create_socket(sk, sk->sk_family, &ssock);
76 	if (err)
77 		return err;
78 
79 	msk->scaling_ratio = tcp_sk(ssock->sk)->scaling_ratio;
80 	WRITE_ONCE(msk->first, ssock->sk);
81 	subflow = mptcp_subflow_ctx(ssock->sk);
82 	list_add(&subflow->node, &msk->conn_list);
83 	sock_hold(ssock->sk);
84 	subflow->request_mptcp = 1;
85 	subflow->subflow_id = msk->subflow_id++;
86 
87 	/* This is the first subflow, always with id 0 */
88 	WRITE_ONCE(subflow->local_id, 0);
89 	mptcp_sock_graft(msk->first, sk->sk_socket);
90 	iput(SOCK_INODE(ssock));
91 
92 	return 0;
93 }
94 
95 /* If the MPC handshake is not started, returns the first subflow,
96  * eventually allocating it.
97  */
__mptcp_nmpc_sk(struct mptcp_sock * msk)98 struct sock *__mptcp_nmpc_sk(struct mptcp_sock *msk)
99 {
100 	struct sock *sk = (struct sock *)msk;
101 	int ret;
102 
103 	if (!((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
104 		return ERR_PTR(-EINVAL);
105 
106 	if (!msk->first) {
107 		ret = __mptcp_socket_create(msk);
108 		if (ret)
109 			return ERR_PTR(ret);
110 	}
111 
112 	return msk->first;
113 }
114 
mptcp_drop(struct sock * sk,struct sk_buff * skb)115 static void mptcp_drop(struct sock *sk, struct sk_buff *skb)
116 {
117 	sk_drops_add(sk, skb);
118 	__kfree_skb(skb);
119 }
120 
mptcp_rmem_fwd_alloc_add(struct sock * sk,int size)121 static void mptcp_rmem_fwd_alloc_add(struct sock *sk, int size)
122 {
123 	WRITE_ONCE(mptcp_sk(sk)->rmem_fwd_alloc,
124 		   mptcp_sk(sk)->rmem_fwd_alloc + size);
125 }
126 
mptcp_rmem_charge(struct sock * sk,int size)127 static void mptcp_rmem_charge(struct sock *sk, int size)
128 {
129 	mptcp_rmem_fwd_alloc_add(sk, -size);
130 }
131 
mptcp_try_coalesce(struct sock * sk,struct sk_buff * to,struct sk_buff * from)132 static bool mptcp_try_coalesce(struct sock *sk, struct sk_buff *to,
133 			       struct sk_buff *from)
134 {
135 	bool fragstolen;
136 	int delta;
137 
138 	if (MPTCP_SKB_CB(from)->offset ||
139 	    ((to->len + from->len) > (sk->sk_rcvbuf >> 3)) ||
140 	    !skb_try_coalesce(to, from, &fragstolen, &delta))
141 		return false;
142 
143 	pr_debug("colesced seq %llx into %llx new len %d new end seq %llx\n",
144 		 MPTCP_SKB_CB(from)->map_seq, MPTCP_SKB_CB(to)->map_seq,
145 		 to->len, MPTCP_SKB_CB(from)->end_seq);
146 	MPTCP_SKB_CB(to)->end_seq = MPTCP_SKB_CB(from)->end_seq;
147 
148 	/* note the fwd memory can reach a negative value after accounting
149 	 * for the delta, but the later skb free will restore a non
150 	 * negative one
151 	 */
152 	atomic_add(delta, &sk->sk_rmem_alloc);
153 	mptcp_rmem_charge(sk, delta);
154 	kfree_skb_partial(from, fragstolen);
155 
156 	return true;
157 }
158 
mptcp_ooo_try_coalesce(struct mptcp_sock * msk,struct sk_buff * to,struct sk_buff * from)159 static bool mptcp_ooo_try_coalesce(struct mptcp_sock *msk, struct sk_buff *to,
160 				   struct sk_buff *from)
161 {
162 	if (MPTCP_SKB_CB(from)->map_seq != MPTCP_SKB_CB(to)->end_seq)
163 		return false;
164 
165 	return mptcp_try_coalesce((struct sock *)msk, to, from);
166 }
167 
__mptcp_rmem_reclaim(struct sock * sk,int amount)168 static void __mptcp_rmem_reclaim(struct sock *sk, int amount)
169 {
170 	amount >>= PAGE_SHIFT;
171 	mptcp_rmem_charge(sk, amount << PAGE_SHIFT);
172 	__sk_mem_reduce_allocated(sk, amount);
173 }
174 
mptcp_rmem_uncharge(struct sock * sk,int size)175 static void mptcp_rmem_uncharge(struct sock *sk, int size)
176 {
177 	struct mptcp_sock *msk = mptcp_sk(sk);
178 	int reclaimable;
179 
180 	mptcp_rmem_fwd_alloc_add(sk, size);
181 	reclaimable = msk->rmem_fwd_alloc - sk_unused_reserved_mem(sk);
182 
183 	/* see sk_mem_uncharge() for the rationale behind the following schema */
184 	if (unlikely(reclaimable >= PAGE_SIZE))
185 		__mptcp_rmem_reclaim(sk, reclaimable);
186 }
187 
mptcp_rfree(struct sk_buff * skb)188 static void mptcp_rfree(struct sk_buff *skb)
189 {
190 	unsigned int len = skb->truesize;
191 	struct sock *sk = skb->sk;
192 
193 	atomic_sub(len, &sk->sk_rmem_alloc);
194 	mptcp_rmem_uncharge(sk, len);
195 }
196 
mptcp_set_owner_r(struct sk_buff * skb,struct sock * sk)197 void mptcp_set_owner_r(struct sk_buff *skb, struct sock *sk)
198 {
199 	skb_orphan(skb);
200 	skb->sk = sk;
201 	skb->destructor = mptcp_rfree;
202 	atomic_add(skb->truesize, &sk->sk_rmem_alloc);
203 	mptcp_rmem_charge(sk, skb->truesize);
204 }
205 
206 /* "inspired" by tcp_data_queue_ofo(), main differences:
207  * - use mptcp seqs
208  * - don't cope with sacks
209  */
mptcp_data_queue_ofo(struct mptcp_sock * msk,struct sk_buff * skb)210 static void mptcp_data_queue_ofo(struct mptcp_sock *msk, struct sk_buff *skb)
211 {
212 	struct sock *sk = (struct sock *)msk;
213 	struct rb_node **p, *parent;
214 	u64 seq, end_seq, max_seq;
215 	struct sk_buff *skb1;
216 
217 	seq = MPTCP_SKB_CB(skb)->map_seq;
218 	end_seq = MPTCP_SKB_CB(skb)->end_seq;
219 	max_seq = atomic64_read(&msk->rcv_wnd_sent);
220 
221 	pr_debug("msk=%p seq=%llx limit=%llx empty=%d\n", msk, seq, max_seq,
222 		 RB_EMPTY_ROOT(&msk->out_of_order_queue));
223 	if (after64(end_seq, max_seq)) {
224 		/* out of window */
225 		mptcp_drop(sk, skb);
226 		pr_debug("oow by %lld, rcv_wnd_sent %llu\n",
227 			 (unsigned long long)end_seq - (unsigned long)max_seq,
228 			 (unsigned long long)atomic64_read(&msk->rcv_wnd_sent));
229 		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_NODSSWINDOW);
230 		return;
231 	}
232 
233 	p = &msk->out_of_order_queue.rb_node;
234 	MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOQUEUE);
235 	if (RB_EMPTY_ROOT(&msk->out_of_order_queue)) {
236 		rb_link_node(&skb->rbnode, NULL, p);
237 		rb_insert_color(&skb->rbnode, &msk->out_of_order_queue);
238 		msk->ooo_last_skb = skb;
239 		goto end;
240 	}
241 
242 	/* with 2 subflows, adding at end of ooo queue is quite likely
243 	 * Use of ooo_last_skb avoids the O(Log(N)) rbtree lookup.
244 	 */
245 	if (mptcp_ooo_try_coalesce(msk, msk->ooo_last_skb, skb)) {
246 		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOMERGE);
247 		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOQUEUETAIL);
248 		return;
249 	}
250 
251 	/* Can avoid an rbtree lookup if we are adding skb after ooo_last_skb */
252 	if (!before64(seq, MPTCP_SKB_CB(msk->ooo_last_skb)->end_seq)) {
253 		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOQUEUETAIL);
254 		parent = &msk->ooo_last_skb->rbnode;
255 		p = &parent->rb_right;
256 		goto insert;
257 	}
258 
259 	/* Find place to insert this segment. Handle overlaps on the way. */
260 	parent = NULL;
261 	while (*p) {
262 		parent = *p;
263 		skb1 = rb_to_skb(parent);
264 		if (before64(seq, MPTCP_SKB_CB(skb1)->map_seq)) {
265 			p = &parent->rb_left;
266 			continue;
267 		}
268 		if (before64(seq, MPTCP_SKB_CB(skb1)->end_seq)) {
269 			if (!after64(end_seq, MPTCP_SKB_CB(skb1)->end_seq)) {
270 				/* All the bits are present. Drop. */
271 				mptcp_drop(sk, skb);
272 				MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
273 				return;
274 			}
275 			if (after64(seq, MPTCP_SKB_CB(skb1)->map_seq)) {
276 				/* partial overlap:
277 				 *     |     skb      |
278 				 *  |     skb1    |
279 				 * continue traversing
280 				 */
281 			} else {
282 				/* skb's seq == skb1's seq and skb covers skb1.
283 				 * Replace skb1 with skb.
284 				 */
285 				rb_replace_node(&skb1->rbnode, &skb->rbnode,
286 						&msk->out_of_order_queue);
287 				mptcp_drop(sk, skb1);
288 				MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
289 				goto merge_right;
290 			}
291 		} else if (mptcp_ooo_try_coalesce(msk, skb1, skb)) {
292 			MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOMERGE);
293 			return;
294 		}
295 		p = &parent->rb_right;
296 	}
297 
298 insert:
299 	/* Insert segment into RB tree. */
300 	rb_link_node(&skb->rbnode, parent, p);
301 	rb_insert_color(&skb->rbnode, &msk->out_of_order_queue);
302 
303 merge_right:
304 	/* Remove other segments covered by skb. */
305 	while ((skb1 = skb_rb_next(skb)) != NULL) {
306 		if (before64(end_seq, MPTCP_SKB_CB(skb1)->end_seq))
307 			break;
308 		rb_erase(&skb1->rbnode, &msk->out_of_order_queue);
309 		mptcp_drop(sk, skb1);
310 		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
311 	}
312 	/* If there is no skb after us, we are the last_skb ! */
313 	if (!skb1)
314 		msk->ooo_last_skb = skb;
315 
316 end:
317 	skb_condense(skb);
318 	mptcp_set_owner_r(skb, sk);
319 }
320 
mptcp_rmem_schedule(struct sock * sk,struct sock * ssk,int size)321 static bool mptcp_rmem_schedule(struct sock *sk, struct sock *ssk, int size)
322 {
323 	struct mptcp_sock *msk = mptcp_sk(sk);
324 	int amt, amount;
325 
326 	if (size <= msk->rmem_fwd_alloc)
327 		return true;
328 
329 	size -= msk->rmem_fwd_alloc;
330 	amt = sk_mem_pages(size);
331 	amount = amt << PAGE_SHIFT;
332 	if (!__sk_mem_raise_allocated(sk, size, amt, SK_MEM_RECV))
333 		return false;
334 
335 	mptcp_rmem_fwd_alloc_add(sk, amount);
336 	return true;
337 }
338 
__mptcp_move_skb(struct mptcp_sock * msk,struct sock * ssk,struct sk_buff * skb,unsigned int offset,size_t copy_len)339 static bool __mptcp_move_skb(struct mptcp_sock *msk, struct sock *ssk,
340 			     struct sk_buff *skb, unsigned int offset,
341 			     size_t copy_len)
342 {
343 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
344 	struct sock *sk = (struct sock *)msk;
345 	struct sk_buff *tail;
346 	bool has_rxtstamp;
347 
348 	__skb_unlink(skb, &ssk->sk_receive_queue);
349 
350 	skb_ext_reset(skb);
351 	skb_orphan(skb);
352 
353 	/* try to fetch required memory from subflow */
354 	if (!mptcp_rmem_schedule(sk, ssk, skb->truesize)) {
355 		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_RCVPRUNED);
356 		goto drop;
357 	}
358 
359 	has_rxtstamp = TCP_SKB_CB(skb)->has_rxtstamp;
360 
361 	/* the skb map_seq accounts for the skb offset:
362 	 * mptcp_subflow_get_mapped_dsn() is based on the current tp->copied_seq
363 	 * value
364 	 */
365 	MPTCP_SKB_CB(skb)->map_seq = mptcp_subflow_get_mapped_dsn(subflow);
366 	MPTCP_SKB_CB(skb)->end_seq = MPTCP_SKB_CB(skb)->map_seq + copy_len;
367 	MPTCP_SKB_CB(skb)->offset = offset;
368 	MPTCP_SKB_CB(skb)->has_rxtstamp = has_rxtstamp;
369 
370 	if (MPTCP_SKB_CB(skb)->map_seq == msk->ack_seq) {
371 		/* in sequence */
372 		msk->bytes_received += copy_len;
373 		WRITE_ONCE(msk->ack_seq, msk->ack_seq + copy_len);
374 		tail = skb_peek_tail(&sk->sk_receive_queue);
375 		if (tail && mptcp_try_coalesce(sk, tail, skb))
376 			return true;
377 
378 		mptcp_set_owner_r(skb, sk);
379 		__skb_queue_tail(&sk->sk_receive_queue, skb);
380 		return true;
381 	} else if (after64(MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq)) {
382 		mptcp_data_queue_ofo(msk, skb);
383 		return false;
384 	}
385 
386 	/* old data, keep it simple and drop the whole pkt, sender
387 	 * will retransmit as needed, if needed.
388 	 */
389 	MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
390 drop:
391 	mptcp_drop(sk, skb);
392 	return false;
393 }
394 
mptcp_stop_rtx_timer(struct sock * sk)395 static void mptcp_stop_rtx_timer(struct sock *sk)
396 {
397 	struct inet_connection_sock *icsk = inet_csk(sk);
398 
399 	sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
400 	mptcp_sk(sk)->timer_ival = 0;
401 }
402 
mptcp_close_wake_up(struct sock * sk)403 static void mptcp_close_wake_up(struct sock *sk)
404 {
405 	if (sock_flag(sk, SOCK_DEAD))
406 		return;
407 
408 	sk->sk_state_change(sk);
409 	if (sk->sk_shutdown == SHUTDOWN_MASK ||
410 	    sk->sk_state == TCP_CLOSE)
411 		sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
412 	else
413 		sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
414 }
415 
416 /* called under the msk socket lock */
mptcp_pending_data_fin_ack(struct sock * sk)417 static bool mptcp_pending_data_fin_ack(struct sock *sk)
418 {
419 	struct mptcp_sock *msk = mptcp_sk(sk);
420 
421 	return ((1 << sk->sk_state) &
422 		(TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK)) &&
423 	       msk->write_seq == READ_ONCE(msk->snd_una);
424 }
425 
mptcp_check_data_fin_ack(struct sock * sk)426 static void mptcp_check_data_fin_ack(struct sock *sk)
427 {
428 	struct mptcp_sock *msk = mptcp_sk(sk);
429 
430 	/* Look for an acknowledged DATA_FIN */
431 	if (mptcp_pending_data_fin_ack(sk)) {
432 		WRITE_ONCE(msk->snd_data_fin_enable, 0);
433 
434 		switch (sk->sk_state) {
435 		case TCP_FIN_WAIT1:
436 			mptcp_set_state(sk, TCP_FIN_WAIT2);
437 			break;
438 		case TCP_CLOSING:
439 		case TCP_LAST_ACK:
440 			mptcp_set_state(sk, TCP_CLOSE);
441 			break;
442 		}
443 
444 		mptcp_close_wake_up(sk);
445 	}
446 }
447 
448 /* can be called with no lock acquired */
mptcp_pending_data_fin(struct sock * sk,u64 * seq)449 static bool mptcp_pending_data_fin(struct sock *sk, u64 *seq)
450 {
451 	struct mptcp_sock *msk = mptcp_sk(sk);
452 
453 	if (READ_ONCE(msk->rcv_data_fin) &&
454 	    ((1 << inet_sk_state_load(sk)) &
455 	     (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_FIN_WAIT2))) {
456 		u64 rcv_data_fin_seq = READ_ONCE(msk->rcv_data_fin_seq);
457 
458 		if (READ_ONCE(msk->ack_seq) == rcv_data_fin_seq) {
459 			if (seq)
460 				*seq = rcv_data_fin_seq;
461 
462 			return true;
463 		}
464 	}
465 
466 	return false;
467 }
468 
mptcp_set_datafin_timeout(struct sock * sk)469 static void mptcp_set_datafin_timeout(struct sock *sk)
470 {
471 	struct inet_connection_sock *icsk = inet_csk(sk);
472 	u32 retransmits;
473 
474 	retransmits = min_t(u32, icsk->icsk_retransmits,
475 			    ilog2(TCP_RTO_MAX / TCP_RTO_MIN));
476 
477 	mptcp_sk(sk)->timer_ival = TCP_RTO_MIN << retransmits;
478 }
479 
__mptcp_set_timeout(struct sock * sk,long tout)480 static void __mptcp_set_timeout(struct sock *sk, long tout)
481 {
482 	mptcp_sk(sk)->timer_ival = tout > 0 ? tout : TCP_RTO_MIN;
483 }
484 
mptcp_timeout_from_subflow(const struct mptcp_subflow_context * subflow)485 static long mptcp_timeout_from_subflow(const struct mptcp_subflow_context *subflow)
486 {
487 	const struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
488 
489 	return inet_csk(ssk)->icsk_pending && !subflow->stale_count ?
490 	       inet_csk(ssk)->icsk_timeout - jiffies : 0;
491 }
492 
mptcp_set_timeout(struct sock * sk)493 static void mptcp_set_timeout(struct sock *sk)
494 {
495 	struct mptcp_subflow_context *subflow;
496 	long tout = 0;
497 
498 	mptcp_for_each_subflow(mptcp_sk(sk), subflow)
499 		tout = max(tout, mptcp_timeout_from_subflow(subflow));
500 	__mptcp_set_timeout(sk, tout);
501 }
502 
tcp_can_send_ack(const struct sock * ssk)503 static inline bool tcp_can_send_ack(const struct sock *ssk)
504 {
505 	return !((1 << inet_sk_state_load(ssk)) &
506 	       (TCPF_SYN_SENT | TCPF_SYN_RECV | TCPF_TIME_WAIT | TCPF_CLOSE | TCPF_LISTEN));
507 }
508 
__mptcp_subflow_send_ack(struct sock * ssk)509 void __mptcp_subflow_send_ack(struct sock *ssk)
510 {
511 	if (tcp_can_send_ack(ssk))
512 		tcp_send_ack(ssk);
513 }
514 
mptcp_subflow_send_ack(struct sock * ssk)515 static void mptcp_subflow_send_ack(struct sock *ssk)
516 {
517 	bool slow;
518 
519 	slow = lock_sock_fast(ssk);
520 	__mptcp_subflow_send_ack(ssk);
521 	unlock_sock_fast(ssk, slow);
522 }
523 
mptcp_send_ack(struct mptcp_sock * msk)524 static void mptcp_send_ack(struct mptcp_sock *msk)
525 {
526 	struct mptcp_subflow_context *subflow;
527 
528 	mptcp_for_each_subflow(msk, subflow)
529 		mptcp_subflow_send_ack(mptcp_subflow_tcp_sock(subflow));
530 }
531 
mptcp_subflow_cleanup_rbuf(struct sock * ssk,int copied)532 static void mptcp_subflow_cleanup_rbuf(struct sock *ssk, int copied)
533 {
534 	bool slow;
535 
536 	slow = lock_sock_fast(ssk);
537 	if (tcp_can_send_ack(ssk))
538 		tcp_cleanup_rbuf(ssk, copied);
539 	unlock_sock_fast(ssk, slow);
540 }
541 
mptcp_subflow_could_cleanup(const struct sock * ssk,bool rx_empty)542 static bool mptcp_subflow_could_cleanup(const struct sock *ssk, bool rx_empty)
543 {
544 	const struct inet_connection_sock *icsk = inet_csk(ssk);
545 	u8 ack_pending = READ_ONCE(icsk->icsk_ack.pending);
546 	const struct tcp_sock *tp = tcp_sk(ssk);
547 
548 	return (ack_pending & ICSK_ACK_SCHED) &&
549 		((READ_ONCE(tp->rcv_nxt) - READ_ONCE(tp->rcv_wup) >
550 		  READ_ONCE(icsk->icsk_ack.rcv_mss)) ||
551 		 (rx_empty && ack_pending &
552 			      (ICSK_ACK_PUSHED2 | ICSK_ACK_PUSHED)));
553 }
554 
mptcp_cleanup_rbuf(struct mptcp_sock * msk,int copied)555 static void mptcp_cleanup_rbuf(struct mptcp_sock *msk, int copied)
556 {
557 	int old_space = READ_ONCE(msk->old_wspace);
558 	struct mptcp_subflow_context *subflow;
559 	struct sock *sk = (struct sock *)msk;
560 	int space =  __mptcp_space(sk);
561 	bool cleanup, rx_empty;
562 
563 	cleanup = (space > 0) && (space >= (old_space << 1)) && copied;
564 	rx_empty = !__mptcp_rmem(sk) && copied;
565 
566 	mptcp_for_each_subflow(msk, subflow) {
567 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
568 
569 		if (cleanup || mptcp_subflow_could_cleanup(ssk, rx_empty))
570 			mptcp_subflow_cleanup_rbuf(ssk, copied);
571 	}
572 }
573 
mptcp_check_data_fin(struct sock * sk)574 static bool mptcp_check_data_fin(struct sock *sk)
575 {
576 	struct mptcp_sock *msk = mptcp_sk(sk);
577 	u64 rcv_data_fin_seq;
578 	bool ret = false;
579 
580 	/* Need to ack a DATA_FIN received from a peer while this side
581 	 * of the connection is in ESTABLISHED, FIN_WAIT1, or FIN_WAIT2.
582 	 * msk->rcv_data_fin was set when parsing the incoming options
583 	 * at the subflow level and the msk lock was not held, so this
584 	 * is the first opportunity to act on the DATA_FIN and change
585 	 * the msk state.
586 	 *
587 	 * If we are caught up to the sequence number of the incoming
588 	 * DATA_FIN, send the DATA_ACK now and do state transition.  If
589 	 * not caught up, do nothing and let the recv code send DATA_ACK
590 	 * when catching up.
591 	 */
592 
593 	if (mptcp_pending_data_fin(sk, &rcv_data_fin_seq)) {
594 		WRITE_ONCE(msk->ack_seq, msk->ack_seq + 1);
595 		WRITE_ONCE(msk->rcv_data_fin, 0);
596 
597 		WRITE_ONCE(sk->sk_shutdown, sk->sk_shutdown | RCV_SHUTDOWN);
598 		smp_mb__before_atomic(); /* SHUTDOWN must be visible first */
599 
600 		switch (sk->sk_state) {
601 		case TCP_ESTABLISHED:
602 			mptcp_set_state(sk, TCP_CLOSE_WAIT);
603 			break;
604 		case TCP_FIN_WAIT1:
605 			mptcp_set_state(sk, TCP_CLOSING);
606 			break;
607 		case TCP_FIN_WAIT2:
608 			mptcp_set_state(sk, TCP_CLOSE);
609 			break;
610 		default:
611 			/* Other states not expected */
612 			WARN_ON_ONCE(1);
613 			break;
614 		}
615 
616 		ret = true;
617 		if (!__mptcp_check_fallback(msk))
618 			mptcp_send_ack(msk);
619 		mptcp_close_wake_up(sk);
620 	}
621 	return ret;
622 }
623 
mptcp_dss_corruption(struct mptcp_sock * msk,struct sock * ssk)624 static void mptcp_dss_corruption(struct mptcp_sock *msk, struct sock *ssk)
625 {
626 	if (READ_ONCE(msk->allow_infinite_fallback)) {
627 		MPTCP_INC_STATS(sock_net(ssk),
628 				MPTCP_MIB_DSSCORRUPTIONFALLBACK);
629 		mptcp_do_fallback(ssk);
630 	} else {
631 		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSCORRUPTIONRESET);
632 		mptcp_subflow_reset(ssk);
633 	}
634 }
635 
__mptcp_move_skbs_from_subflow(struct mptcp_sock * msk,struct sock * ssk,unsigned int * bytes)636 static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,
637 					   struct sock *ssk,
638 					   unsigned int *bytes)
639 {
640 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
641 	struct sock *sk = (struct sock *)msk;
642 	unsigned int moved = 0;
643 	bool more_data_avail;
644 	struct tcp_sock *tp;
645 	bool done = false;
646 	int sk_rbuf;
647 
648 	sk_rbuf = READ_ONCE(sk->sk_rcvbuf);
649 
650 	if (!(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
651 		int ssk_rbuf = READ_ONCE(ssk->sk_rcvbuf);
652 
653 		if (unlikely(ssk_rbuf > sk_rbuf)) {
654 			WRITE_ONCE(sk->sk_rcvbuf, ssk_rbuf);
655 			sk_rbuf = ssk_rbuf;
656 		}
657 	}
658 
659 	pr_debug("msk=%p ssk=%p\n", msk, ssk);
660 	tp = tcp_sk(ssk);
661 	do {
662 		u32 map_remaining, offset;
663 		u32 seq = tp->copied_seq;
664 		struct sk_buff *skb;
665 		bool fin;
666 
667 		/* try to move as much data as available */
668 		map_remaining = subflow->map_data_len -
669 				mptcp_subflow_get_map_offset(subflow);
670 
671 		skb = skb_peek(&ssk->sk_receive_queue);
672 		if (!skb) {
673 			/* With racing move_skbs_to_msk() and __mptcp_move_skbs(),
674 			 * a different CPU can have already processed the pending
675 			 * data, stop here or we can enter an infinite loop
676 			 */
677 			if (!moved)
678 				done = true;
679 			break;
680 		}
681 
682 		if (__mptcp_check_fallback(msk)) {
683 			/* Under fallback skbs have no MPTCP extension and TCP could
684 			 * collapse them between the dummy map creation and the
685 			 * current dequeue. Be sure to adjust the map size.
686 			 */
687 			map_remaining = skb->len;
688 			subflow->map_data_len = skb->len;
689 		}
690 
691 		offset = seq - TCP_SKB_CB(skb)->seq;
692 		fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
693 		if (fin) {
694 			done = true;
695 			seq++;
696 		}
697 
698 		if (offset < skb->len) {
699 			size_t len = skb->len - offset;
700 
701 			if (tp->urg_data)
702 				done = true;
703 
704 			if (__mptcp_move_skb(msk, ssk, skb, offset, len))
705 				moved += len;
706 			seq += len;
707 
708 			if (unlikely(map_remaining < len)) {
709 				DEBUG_NET_WARN_ON_ONCE(1);
710 				mptcp_dss_corruption(msk, ssk);
711 			}
712 		} else {
713 			if (unlikely(!fin)) {
714 				DEBUG_NET_WARN_ON_ONCE(1);
715 				mptcp_dss_corruption(msk, ssk);
716 			}
717 
718 			sk_eat_skb(ssk, skb);
719 			done = true;
720 		}
721 
722 		WRITE_ONCE(tp->copied_seq, seq);
723 		more_data_avail = mptcp_subflow_data_available(ssk);
724 
725 		if (atomic_read(&sk->sk_rmem_alloc) > sk_rbuf) {
726 			done = true;
727 			break;
728 		}
729 	} while (more_data_avail);
730 
731 	if (moved > 0)
732 		msk->last_data_recv = tcp_jiffies32;
733 	*bytes += moved;
734 	return done;
735 }
736 
__mptcp_ofo_queue(struct mptcp_sock * msk)737 static bool __mptcp_ofo_queue(struct mptcp_sock *msk)
738 {
739 	struct sock *sk = (struct sock *)msk;
740 	struct sk_buff *skb, *tail;
741 	bool moved = false;
742 	struct rb_node *p;
743 	u64 end_seq;
744 
745 	p = rb_first(&msk->out_of_order_queue);
746 	pr_debug("msk=%p empty=%d\n", msk, RB_EMPTY_ROOT(&msk->out_of_order_queue));
747 	while (p) {
748 		skb = rb_to_skb(p);
749 		if (after64(MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq))
750 			break;
751 
752 		p = rb_next(p);
753 		rb_erase(&skb->rbnode, &msk->out_of_order_queue);
754 
755 		if (unlikely(!after64(MPTCP_SKB_CB(skb)->end_seq,
756 				      msk->ack_seq))) {
757 			mptcp_drop(sk, skb);
758 			MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
759 			continue;
760 		}
761 
762 		end_seq = MPTCP_SKB_CB(skb)->end_seq;
763 		tail = skb_peek_tail(&sk->sk_receive_queue);
764 		if (!tail || !mptcp_ooo_try_coalesce(msk, tail, skb)) {
765 			int delta = msk->ack_seq - MPTCP_SKB_CB(skb)->map_seq;
766 
767 			/* skip overlapping data, if any */
768 			pr_debug("uncoalesced seq=%llx ack seq=%llx delta=%d\n",
769 				 MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq,
770 				 delta);
771 			MPTCP_SKB_CB(skb)->offset += delta;
772 			MPTCP_SKB_CB(skb)->map_seq += delta;
773 			__skb_queue_tail(&sk->sk_receive_queue, skb);
774 		}
775 		msk->bytes_received += end_seq - msk->ack_seq;
776 		WRITE_ONCE(msk->ack_seq, end_seq);
777 		moved = true;
778 	}
779 	return moved;
780 }
781 
__mptcp_subflow_error_report(struct sock * sk,struct sock * ssk)782 static bool __mptcp_subflow_error_report(struct sock *sk, struct sock *ssk)
783 {
784 	int err = sock_error(ssk);
785 	int ssk_state;
786 
787 	if (!err)
788 		return false;
789 
790 	/* only propagate errors on fallen-back sockets or
791 	 * on MPC connect
792 	 */
793 	if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(mptcp_sk(sk)))
794 		return false;
795 
796 	/* We need to propagate only transition to CLOSE state.
797 	 * Orphaned socket will see such state change via
798 	 * subflow_sched_work_if_closed() and that path will properly
799 	 * destroy the msk as needed.
800 	 */
801 	ssk_state = inet_sk_state_load(ssk);
802 	if (ssk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DEAD))
803 		mptcp_set_state(sk, ssk_state);
804 	WRITE_ONCE(sk->sk_err, -err);
805 
806 	/* This barrier is coupled with smp_rmb() in mptcp_poll() */
807 	smp_wmb();
808 	sk_error_report(sk);
809 	return true;
810 }
811 
__mptcp_error_report(struct sock * sk)812 void __mptcp_error_report(struct sock *sk)
813 {
814 	struct mptcp_subflow_context *subflow;
815 	struct mptcp_sock *msk = mptcp_sk(sk);
816 
817 	mptcp_for_each_subflow(msk, subflow)
818 		if (__mptcp_subflow_error_report(sk, mptcp_subflow_tcp_sock(subflow)))
819 			break;
820 }
821 
822 /* In most cases we will be able to lock the mptcp socket.  If its already
823  * owned, we need to defer to the work queue to avoid ABBA deadlock.
824  */
move_skbs_to_msk(struct mptcp_sock * msk,struct sock * ssk)825 static bool move_skbs_to_msk(struct mptcp_sock *msk, struct sock *ssk)
826 {
827 	struct sock *sk = (struct sock *)msk;
828 	unsigned int moved = 0;
829 
830 	__mptcp_move_skbs_from_subflow(msk, ssk, &moved);
831 	__mptcp_ofo_queue(msk);
832 	if (unlikely(ssk->sk_err)) {
833 		if (!sock_owned_by_user(sk))
834 			__mptcp_error_report(sk);
835 		else
836 			__set_bit(MPTCP_ERROR_REPORT,  &msk->cb_flags);
837 	}
838 
839 	/* If the moves have caught up with the DATA_FIN sequence number
840 	 * it's time to ack the DATA_FIN and change socket state, but
841 	 * this is not a good place to change state. Let the workqueue
842 	 * do it.
843 	 */
844 	if (mptcp_pending_data_fin(sk, NULL))
845 		mptcp_schedule_work(sk);
846 	return moved > 0;
847 }
848 
mptcp_data_ready(struct sock * sk,struct sock * ssk)849 void mptcp_data_ready(struct sock *sk, struct sock *ssk)
850 {
851 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
852 	struct mptcp_sock *msk = mptcp_sk(sk);
853 	int sk_rbuf, ssk_rbuf;
854 
855 	/* The peer can send data while we are shutting down this
856 	 * subflow at msk destruction time, but we must avoid enqueuing
857 	 * more data to the msk receive queue
858 	 */
859 	if (unlikely(subflow->disposable))
860 		return;
861 
862 	ssk_rbuf = READ_ONCE(ssk->sk_rcvbuf);
863 	sk_rbuf = READ_ONCE(sk->sk_rcvbuf);
864 	if (unlikely(ssk_rbuf > sk_rbuf))
865 		sk_rbuf = ssk_rbuf;
866 
867 	/* over limit? can't append more skbs to msk, Also, no need to wake-up*/
868 	if (__mptcp_rmem(sk) > sk_rbuf)
869 		return;
870 
871 	/* Wake-up the reader only for in-sequence data */
872 	mptcp_data_lock(sk);
873 	if (move_skbs_to_msk(msk, ssk) && mptcp_epollin_ready(sk))
874 		sk->sk_data_ready(sk);
875 	mptcp_data_unlock(sk);
876 }
877 
mptcp_subflow_joined(struct mptcp_sock * msk,struct sock * ssk)878 static void mptcp_subflow_joined(struct mptcp_sock *msk, struct sock *ssk)
879 {
880 	mptcp_subflow_ctx(ssk)->map_seq = READ_ONCE(msk->ack_seq);
881 	WRITE_ONCE(msk->allow_infinite_fallback, false);
882 	mptcp_event(MPTCP_EVENT_SUB_ESTABLISHED, msk, ssk, GFP_ATOMIC);
883 }
884 
__mptcp_finish_join(struct mptcp_sock * msk,struct sock * ssk)885 static bool __mptcp_finish_join(struct mptcp_sock *msk, struct sock *ssk)
886 {
887 	struct sock *sk = (struct sock *)msk;
888 
889 	if (sk->sk_state != TCP_ESTABLISHED)
890 		return false;
891 
892 	/* attach to msk socket only after we are sure we will deal with it
893 	 * at close time
894 	 */
895 	if (sk->sk_socket && !ssk->sk_socket)
896 		mptcp_sock_graft(ssk, sk->sk_socket);
897 
898 	mptcp_subflow_ctx(ssk)->subflow_id = msk->subflow_id++;
899 	mptcp_sockopt_sync_locked(msk, ssk);
900 	mptcp_subflow_joined(msk, ssk);
901 	mptcp_stop_tout_timer(sk);
902 	__mptcp_propagate_sndbuf(sk, ssk);
903 	return true;
904 }
905 
__mptcp_flush_join_list(struct sock * sk,struct list_head * join_list)906 static void __mptcp_flush_join_list(struct sock *sk, struct list_head *join_list)
907 {
908 	struct mptcp_subflow_context *tmp, *subflow;
909 	struct mptcp_sock *msk = mptcp_sk(sk);
910 
911 	list_for_each_entry_safe(subflow, tmp, join_list, node) {
912 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
913 		bool slow = lock_sock_fast(ssk);
914 
915 		list_move_tail(&subflow->node, &msk->conn_list);
916 		if (!__mptcp_finish_join(msk, ssk))
917 			mptcp_subflow_reset(ssk);
918 		unlock_sock_fast(ssk, slow);
919 	}
920 }
921 
mptcp_rtx_timer_pending(struct sock * sk)922 static bool mptcp_rtx_timer_pending(struct sock *sk)
923 {
924 	return timer_pending(&inet_csk(sk)->icsk_retransmit_timer);
925 }
926 
mptcp_reset_rtx_timer(struct sock * sk)927 static void mptcp_reset_rtx_timer(struct sock *sk)
928 {
929 	struct inet_connection_sock *icsk = inet_csk(sk);
930 	unsigned long tout;
931 
932 	/* prevent rescheduling on close */
933 	if (unlikely(inet_sk_state_load(sk) == TCP_CLOSE))
934 		return;
935 
936 	tout = mptcp_sk(sk)->timer_ival;
937 	sk_reset_timer(sk, &icsk->icsk_retransmit_timer, jiffies + tout);
938 }
939 
mptcp_schedule_work(struct sock * sk)940 bool mptcp_schedule_work(struct sock *sk)
941 {
942 	if (inet_sk_state_load(sk) != TCP_CLOSE &&
943 	    schedule_work(&mptcp_sk(sk)->work)) {
944 		/* each subflow already holds a reference to the sk, and the
945 		 * workqueue is invoked by a subflow, so sk can't go away here.
946 		 */
947 		sock_hold(sk);
948 		return true;
949 	}
950 	return false;
951 }
952 
mptcp_subflow_recv_lookup(const struct mptcp_sock * msk)953 static struct sock *mptcp_subflow_recv_lookup(const struct mptcp_sock *msk)
954 {
955 	struct mptcp_subflow_context *subflow;
956 
957 	msk_owned_by_me(msk);
958 
959 	mptcp_for_each_subflow(msk, subflow) {
960 		if (READ_ONCE(subflow->data_avail))
961 			return mptcp_subflow_tcp_sock(subflow);
962 	}
963 
964 	return NULL;
965 }
966 
mptcp_skb_can_collapse_to(u64 write_seq,const struct sk_buff * skb,const struct mptcp_ext * mpext)967 static bool mptcp_skb_can_collapse_to(u64 write_seq,
968 				      const struct sk_buff *skb,
969 				      const struct mptcp_ext *mpext)
970 {
971 	if (!tcp_skb_can_collapse_to(skb))
972 		return false;
973 
974 	/* can collapse only if MPTCP level sequence is in order and this
975 	 * mapping has not been xmitted yet
976 	 */
977 	return mpext && mpext->data_seq + mpext->data_len == write_seq &&
978 	       !mpext->frozen;
979 }
980 
981 /* we can append data to the given data frag if:
982  * - there is space available in the backing page_frag
983  * - the data frag tail matches the current page_frag free offset
984  * - the data frag end sequence number matches the current write seq
985  */
mptcp_frag_can_collapse_to(const struct mptcp_sock * msk,const struct page_frag * pfrag,const struct mptcp_data_frag * df)986 static bool mptcp_frag_can_collapse_to(const struct mptcp_sock *msk,
987 				       const struct page_frag *pfrag,
988 				       const struct mptcp_data_frag *df)
989 {
990 	return df && pfrag->page == df->page &&
991 		pfrag->size - pfrag->offset > 0 &&
992 		pfrag->offset == (df->offset + df->data_len) &&
993 		df->data_seq + df->data_len == msk->write_seq;
994 }
995 
dfrag_uncharge(struct sock * sk,int len)996 static void dfrag_uncharge(struct sock *sk, int len)
997 {
998 	sk_mem_uncharge(sk, len);
999 	sk_wmem_queued_add(sk, -len);
1000 }
1001 
dfrag_clear(struct sock * sk,struct mptcp_data_frag * dfrag)1002 static void dfrag_clear(struct sock *sk, struct mptcp_data_frag *dfrag)
1003 {
1004 	int len = dfrag->data_len + dfrag->overhead;
1005 
1006 	list_del(&dfrag->list);
1007 	dfrag_uncharge(sk, len);
1008 	put_page(dfrag->page);
1009 }
1010 
1011 /* called under both the msk socket lock and the data lock */
__mptcp_clean_una(struct sock * sk)1012 static void __mptcp_clean_una(struct sock *sk)
1013 {
1014 	struct mptcp_sock *msk = mptcp_sk(sk);
1015 	struct mptcp_data_frag *dtmp, *dfrag;
1016 	u64 snd_una;
1017 
1018 	snd_una = msk->snd_una;
1019 	list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list) {
1020 		if (after64(dfrag->data_seq + dfrag->data_len, snd_una))
1021 			break;
1022 
1023 		if (unlikely(dfrag == msk->first_pending)) {
1024 			/* in recovery mode can see ack after the current snd head */
1025 			if (WARN_ON_ONCE(!msk->recovery))
1026 				break;
1027 
1028 			WRITE_ONCE(msk->first_pending, mptcp_send_next(sk));
1029 		}
1030 
1031 		dfrag_clear(sk, dfrag);
1032 	}
1033 
1034 	dfrag = mptcp_rtx_head(sk);
1035 	if (dfrag && after64(snd_una, dfrag->data_seq)) {
1036 		u64 delta = snd_una - dfrag->data_seq;
1037 
1038 		/* prevent wrap around in recovery mode */
1039 		if (unlikely(delta > dfrag->already_sent)) {
1040 			if (WARN_ON_ONCE(!msk->recovery))
1041 				goto out;
1042 			if (WARN_ON_ONCE(delta > dfrag->data_len))
1043 				goto out;
1044 			dfrag->already_sent += delta - dfrag->already_sent;
1045 		}
1046 
1047 		dfrag->data_seq += delta;
1048 		dfrag->offset += delta;
1049 		dfrag->data_len -= delta;
1050 		dfrag->already_sent -= delta;
1051 
1052 		dfrag_uncharge(sk, delta);
1053 	}
1054 
1055 	/* all retransmitted data acked, recovery completed */
1056 	if (unlikely(msk->recovery) && after64(msk->snd_una, msk->recovery_snd_nxt))
1057 		msk->recovery = false;
1058 
1059 out:
1060 	if (snd_una == msk->snd_nxt && snd_una == msk->write_seq) {
1061 		if (mptcp_rtx_timer_pending(sk) && !mptcp_data_fin_enabled(msk))
1062 			mptcp_stop_rtx_timer(sk);
1063 	} else {
1064 		mptcp_reset_rtx_timer(sk);
1065 	}
1066 
1067 	if (mptcp_pending_data_fin_ack(sk))
1068 		mptcp_schedule_work(sk);
1069 }
1070 
__mptcp_clean_una_wakeup(struct sock * sk)1071 static void __mptcp_clean_una_wakeup(struct sock *sk)
1072 {
1073 	lockdep_assert_held_once(&sk->sk_lock.slock);
1074 
1075 	__mptcp_clean_una(sk);
1076 	mptcp_write_space(sk);
1077 }
1078 
mptcp_clean_una_wakeup(struct sock * sk)1079 static void mptcp_clean_una_wakeup(struct sock *sk)
1080 {
1081 	mptcp_data_lock(sk);
1082 	__mptcp_clean_una_wakeup(sk);
1083 	mptcp_data_unlock(sk);
1084 }
1085 
mptcp_enter_memory_pressure(struct sock * sk)1086 static void mptcp_enter_memory_pressure(struct sock *sk)
1087 {
1088 	struct mptcp_subflow_context *subflow;
1089 	struct mptcp_sock *msk = mptcp_sk(sk);
1090 	bool first = true;
1091 
1092 	mptcp_for_each_subflow(msk, subflow) {
1093 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
1094 
1095 		if (first)
1096 			tcp_enter_memory_pressure(ssk);
1097 		sk_stream_moderate_sndbuf(ssk);
1098 
1099 		first = false;
1100 	}
1101 	__mptcp_sync_sndbuf(sk);
1102 }
1103 
1104 /* ensure we get enough memory for the frag hdr, beyond some minimal amount of
1105  * data
1106  */
mptcp_page_frag_refill(struct sock * sk,struct page_frag * pfrag)1107 static bool mptcp_page_frag_refill(struct sock *sk, struct page_frag *pfrag)
1108 {
1109 	if (likely(skb_page_frag_refill(32U + sizeof(struct mptcp_data_frag),
1110 					pfrag, sk->sk_allocation)))
1111 		return true;
1112 
1113 	mptcp_enter_memory_pressure(sk);
1114 	return false;
1115 }
1116 
1117 static struct mptcp_data_frag *
mptcp_carve_data_frag(const struct mptcp_sock * msk,struct page_frag * pfrag,int orig_offset)1118 mptcp_carve_data_frag(const struct mptcp_sock *msk, struct page_frag *pfrag,
1119 		      int orig_offset)
1120 {
1121 	int offset = ALIGN(orig_offset, sizeof(long));
1122 	struct mptcp_data_frag *dfrag;
1123 
1124 	dfrag = (struct mptcp_data_frag *)(page_to_virt(pfrag->page) + offset);
1125 	dfrag->data_len = 0;
1126 	dfrag->data_seq = msk->write_seq;
1127 	dfrag->overhead = offset - orig_offset + sizeof(struct mptcp_data_frag);
1128 	dfrag->offset = offset + sizeof(struct mptcp_data_frag);
1129 	dfrag->already_sent = 0;
1130 	dfrag->page = pfrag->page;
1131 
1132 	return dfrag;
1133 }
1134 
1135 struct mptcp_sendmsg_info {
1136 	int mss_now;
1137 	int size_goal;
1138 	u16 limit;
1139 	u16 sent;
1140 	unsigned int flags;
1141 	bool data_lock_held;
1142 };
1143 
mptcp_check_allowed_size(const struct mptcp_sock * msk,struct sock * ssk,u64 data_seq,int avail_size)1144 static int mptcp_check_allowed_size(const struct mptcp_sock *msk, struct sock *ssk,
1145 				    u64 data_seq, int avail_size)
1146 {
1147 	u64 window_end = mptcp_wnd_end(msk);
1148 	u64 mptcp_snd_wnd;
1149 
1150 	if (__mptcp_check_fallback(msk))
1151 		return avail_size;
1152 
1153 	mptcp_snd_wnd = window_end - data_seq;
1154 	avail_size = min_t(unsigned int, mptcp_snd_wnd, avail_size);
1155 
1156 	if (unlikely(tcp_sk(ssk)->snd_wnd < mptcp_snd_wnd)) {
1157 		tcp_sk(ssk)->snd_wnd = min_t(u64, U32_MAX, mptcp_snd_wnd);
1158 		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_SNDWNDSHARED);
1159 	}
1160 
1161 	return avail_size;
1162 }
1163 
__mptcp_add_ext(struct sk_buff * skb,gfp_t gfp)1164 static bool __mptcp_add_ext(struct sk_buff *skb, gfp_t gfp)
1165 {
1166 	struct skb_ext *mpext = __skb_ext_alloc(gfp);
1167 
1168 	if (!mpext)
1169 		return false;
1170 	__skb_ext_set(skb, SKB_EXT_MPTCP, mpext);
1171 	return true;
1172 }
1173 
__mptcp_do_alloc_tx_skb(struct sock * sk,gfp_t gfp)1174 static struct sk_buff *__mptcp_do_alloc_tx_skb(struct sock *sk, gfp_t gfp)
1175 {
1176 	struct sk_buff *skb;
1177 
1178 	skb = alloc_skb_fclone(MAX_TCP_HEADER, gfp);
1179 	if (likely(skb)) {
1180 		if (likely(__mptcp_add_ext(skb, gfp))) {
1181 			skb_reserve(skb, MAX_TCP_HEADER);
1182 			skb->ip_summed = CHECKSUM_PARTIAL;
1183 			INIT_LIST_HEAD(&skb->tcp_tsorted_anchor);
1184 			return skb;
1185 		}
1186 		__kfree_skb(skb);
1187 	} else {
1188 		mptcp_enter_memory_pressure(sk);
1189 	}
1190 	return NULL;
1191 }
1192 
__mptcp_alloc_tx_skb(struct sock * sk,struct sock * ssk,gfp_t gfp)1193 static struct sk_buff *__mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, gfp_t gfp)
1194 {
1195 	struct sk_buff *skb;
1196 
1197 	skb = __mptcp_do_alloc_tx_skb(sk, gfp);
1198 	if (!skb)
1199 		return NULL;
1200 
1201 	if (likely(sk_wmem_schedule(ssk, skb->truesize))) {
1202 		tcp_skb_entail(ssk, skb);
1203 		return skb;
1204 	}
1205 	tcp_skb_tsorted_anchor_cleanup(skb);
1206 	kfree_skb(skb);
1207 	return NULL;
1208 }
1209 
mptcp_alloc_tx_skb(struct sock * sk,struct sock * ssk,bool data_lock_held)1210 static struct sk_buff *mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, bool data_lock_held)
1211 {
1212 	gfp_t gfp = data_lock_held ? GFP_ATOMIC : sk->sk_allocation;
1213 
1214 	return __mptcp_alloc_tx_skb(sk, ssk, gfp);
1215 }
1216 
1217 /* note: this always recompute the csum on the whole skb, even
1218  * if we just appended a single frag. More status info needed
1219  */
mptcp_update_data_checksum(struct sk_buff * skb,int added)1220 static void mptcp_update_data_checksum(struct sk_buff *skb, int added)
1221 {
1222 	struct mptcp_ext *mpext = mptcp_get_ext(skb);
1223 	__wsum csum = ~csum_unfold(mpext->csum);
1224 	int offset = skb->len - added;
1225 
1226 	mpext->csum = csum_fold(csum_block_add(csum, skb_checksum(skb, offset, added, 0), offset));
1227 }
1228 
mptcp_update_infinite_map(struct mptcp_sock * msk,struct sock * ssk,struct mptcp_ext * mpext)1229 static void mptcp_update_infinite_map(struct mptcp_sock *msk,
1230 				      struct sock *ssk,
1231 				      struct mptcp_ext *mpext)
1232 {
1233 	if (!mpext)
1234 		return;
1235 
1236 	mpext->infinite_map = 1;
1237 	mpext->data_len = 0;
1238 
1239 	MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPTX);
1240 	mptcp_subflow_ctx(ssk)->send_infinite_map = 0;
1241 	pr_fallback(msk);
1242 	mptcp_do_fallback(ssk);
1243 }
1244 
1245 #define MPTCP_MAX_GSO_SIZE (GSO_LEGACY_MAX_SIZE - (MAX_TCP_HEADER + 1))
1246 
mptcp_sendmsg_frag(struct sock * sk,struct sock * ssk,struct mptcp_data_frag * dfrag,struct mptcp_sendmsg_info * info)1247 static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
1248 			      struct mptcp_data_frag *dfrag,
1249 			      struct mptcp_sendmsg_info *info)
1250 {
1251 	u64 data_seq = dfrag->data_seq + info->sent;
1252 	int offset = dfrag->offset + info->sent;
1253 	struct mptcp_sock *msk = mptcp_sk(sk);
1254 	bool zero_window_probe = false;
1255 	struct mptcp_ext *mpext = NULL;
1256 	bool can_coalesce = false;
1257 	bool reuse_skb = true;
1258 	struct sk_buff *skb;
1259 	size_t copy;
1260 	int i;
1261 
1262 	pr_debug("msk=%p ssk=%p sending dfrag at seq=%llu len=%u already sent=%u\n",
1263 		 msk, ssk, dfrag->data_seq, dfrag->data_len, info->sent);
1264 
1265 	if (WARN_ON_ONCE(info->sent > info->limit ||
1266 			 info->limit > dfrag->data_len))
1267 		return 0;
1268 
1269 	if (unlikely(!__tcp_can_send(ssk)))
1270 		return -EAGAIN;
1271 
1272 	/* compute send limit */
1273 	if (unlikely(ssk->sk_gso_max_size > MPTCP_MAX_GSO_SIZE))
1274 		ssk->sk_gso_max_size = MPTCP_MAX_GSO_SIZE;
1275 	info->mss_now = tcp_send_mss(ssk, &info->size_goal, info->flags);
1276 	copy = info->size_goal;
1277 
1278 	skb = tcp_write_queue_tail(ssk);
1279 	if (skb && copy > skb->len) {
1280 		/* Limit the write to the size available in the
1281 		 * current skb, if any, so that we create at most a new skb.
1282 		 * Explicitly tells TCP internals to avoid collapsing on later
1283 		 * queue management operation, to avoid breaking the ext <->
1284 		 * SSN association set here
1285 		 */
1286 		mpext = mptcp_get_ext(skb);
1287 		if (!mptcp_skb_can_collapse_to(data_seq, skb, mpext)) {
1288 			TCP_SKB_CB(skb)->eor = 1;
1289 			tcp_mark_push(tcp_sk(ssk), skb);
1290 			goto alloc_skb;
1291 		}
1292 
1293 		i = skb_shinfo(skb)->nr_frags;
1294 		can_coalesce = skb_can_coalesce(skb, i, dfrag->page, offset);
1295 		if (!can_coalesce && i >= READ_ONCE(net_hotdata.sysctl_max_skb_frags)) {
1296 			tcp_mark_push(tcp_sk(ssk), skb);
1297 			goto alloc_skb;
1298 		}
1299 
1300 		copy -= skb->len;
1301 	} else {
1302 alloc_skb:
1303 		skb = mptcp_alloc_tx_skb(sk, ssk, info->data_lock_held);
1304 		if (!skb)
1305 			return -ENOMEM;
1306 
1307 		i = skb_shinfo(skb)->nr_frags;
1308 		reuse_skb = false;
1309 		mpext = mptcp_get_ext(skb);
1310 	}
1311 
1312 	/* Zero window and all data acked? Probe. */
1313 	copy = mptcp_check_allowed_size(msk, ssk, data_seq, copy);
1314 	if (copy == 0) {
1315 		u64 snd_una = READ_ONCE(msk->snd_una);
1316 
1317 		if (snd_una != msk->snd_nxt || tcp_write_queue_tail(ssk)) {
1318 			tcp_remove_empty_skb(ssk);
1319 			return 0;
1320 		}
1321 
1322 		zero_window_probe = true;
1323 		data_seq = snd_una - 1;
1324 		copy = 1;
1325 	}
1326 
1327 	copy = min_t(size_t, copy, info->limit - info->sent);
1328 	if (!sk_wmem_schedule(ssk, copy)) {
1329 		tcp_remove_empty_skb(ssk);
1330 		return -ENOMEM;
1331 	}
1332 
1333 	if (can_coalesce) {
1334 		skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1335 	} else {
1336 		get_page(dfrag->page);
1337 		skb_fill_page_desc(skb, i, dfrag->page, offset, copy);
1338 	}
1339 
1340 	skb->len += copy;
1341 	skb->data_len += copy;
1342 	skb->truesize += copy;
1343 	sk_wmem_queued_add(ssk, copy);
1344 	sk_mem_charge(ssk, copy);
1345 	WRITE_ONCE(tcp_sk(ssk)->write_seq, tcp_sk(ssk)->write_seq + copy);
1346 	TCP_SKB_CB(skb)->end_seq += copy;
1347 	tcp_skb_pcount_set(skb, 0);
1348 
1349 	/* on skb reuse we just need to update the DSS len */
1350 	if (reuse_skb) {
1351 		TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
1352 		mpext->data_len += copy;
1353 		goto out;
1354 	}
1355 
1356 	memset(mpext, 0, sizeof(*mpext));
1357 	mpext->data_seq = data_seq;
1358 	mpext->subflow_seq = mptcp_subflow_ctx(ssk)->rel_write_seq;
1359 	mpext->data_len = copy;
1360 	mpext->use_map = 1;
1361 	mpext->dsn64 = 1;
1362 
1363 	pr_debug("data_seq=%llu subflow_seq=%u data_len=%u dsn64=%d\n",
1364 		 mpext->data_seq, mpext->subflow_seq, mpext->data_len,
1365 		 mpext->dsn64);
1366 
1367 	if (zero_window_probe) {
1368 		mptcp_subflow_ctx(ssk)->rel_write_seq += copy;
1369 		mpext->frozen = 1;
1370 		if (READ_ONCE(msk->csum_enabled))
1371 			mptcp_update_data_checksum(skb, copy);
1372 		tcp_push_pending_frames(ssk);
1373 		return 0;
1374 	}
1375 out:
1376 	if (READ_ONCE(msk->csum_enabled))
1377 		mptcp_update_data_checksum(skb, copy);
1378 	if (mptcp_subflow_ctx(ssk)->send_infinite_map)
1379 		mptcp_update_infinite_map(msk, ssk, mpext);
1380 	trace_mptcp_sendmsg_frag(mpext);
1381 	mptcp_subflow_ctx(ssk)->rel_write_seq += copy;
1382 	return copy;
1383 }
1384 
1385 #define MPTCP_SEND_BURST_SIZE		((1 << 16) - \
1386 					 sizeof(struct tcphdr) - \
1387 					 MAX_TCP_OPTION_SPACE - \
1388 					 sizeof(struct ipv6hdr) - \
1389 					 sizeof(struct frag_hdr))
1390 
1391 struct subflow_send_info {
1392 	struct sock *ssk;
1393 	u64 linger_time;
1394 };
1395 
mptcp_subflow_set_active(struct mptcp_subflow_context * subflow)1396 void mptcp_subflow_set_active(struct mptcp_subflow_context *subflow)
1397 {
1398 	if (!subflow->stale)
1399 		return;
1400 
1401 	subflow->stale = 0;
1402 	MPTCP_INC_STATS(sock_net(mptcp_subflow_tcp_sock(subflow)), MPTCP_MIB_SUBFLOWRECOVER);
1403 }
1404 
mptcp_subflow_active(struct mptcp_subflow_context * subflow)1405 bool mptcp_subflow_active(struct mptcp_subflow_context *subflow)
1406 {
1407 	if (unlikely(subflow->stale)) {
1408 		u32 rcv_tstamp = READ_ONCE(tcp_sk(mptcp_subflow_tcp_sock(subflow))->rcv_tstamp);
1409 
1410 		if (subflow->stale_rcv_tstamp == rcv_tstamp)
1411 			return false;
1412 
1413 		mptcp_subflow_set_active(subflow);
1414 	}
1415 	return __mptcp_subflow_active(subflow);
1416 }
1417 
1418 #define SSK_MODE_ACTIVE	0
1419 #define SSK_MODE_BACKUP	1
1420 #define SSK_MODE_MAX	2
1421 
1422 /* implement the mptcp packet scheduler;
1423  * returns the subflow that will transmit the next DSS
1424  * additionally updates the rtx timeout
1425  */
mptcp_subflow_get_send(struct mptcp_sock * msk)1426 struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
1427 {
1428 	struct subflow_send_info send_info[SSK_MODE_MAX];
1429 	struct mptcp_subflow_context *subflow;
1430 	struct sock *sk = (struct sock *)msk;
1431 	u32 pace, burst, wmem;
1432 	int i, nr_active = 0;
1433 	struct sock *ssk;
1434 	u64 linger_time;
1435 	long tout = 0;
1436 
1437 	/* pick the subflow with the lower wmem/wspace ratio */
1438 	for (i = 0; i < SSK_MODE_MAX; ++i) {
1439 		send_info[i].ssk = NULL;
1440 		send_info[i].linger_time = -1;
1441 	}
1442 
1443 	mptcp_for_each_subflow(msk, subflow) {
1444 		bool backup = subflow->backup || subflow->request_bkup;
1445 
1446 		trace_mptcp_subflow_get_send(subflow);
1447 		ssk =  mptcp_subflow_tcp_sock(subflow);
1448 		if (!mptcp_subflow_active(subflow))
1449 			continue;
1450 
1451 		tout = max(tout, mptcp_timeout_from_subflow(subflow));
1452 		nr_active += !backup;
1453 		pace = subflow->avg_pacing_rate;
1454 		if (unlikely(!pace)) {
1455 			/* init pacing rate from socket */
1456 			subflow->avg_pacing_rate = READ_ONCE(ssk->sk_pacing_rate);
1457 			pace = subflow->avg_pacing_rate;
1458 			if (!pace)
1459 				continue;
1460 		}
1461 
1462 		linger_time = div_u64((u64)READ_ONCE(ssk->sk_wmem_queued) << 32, pace);
1463 		if (linger_time < send_info[backup].linger_time) {
1464 			send_info[backup].ssk = ssk;
1465 			send_info[backup].linger_time = linger_time;
1466 		}
1467 	}
1468 	__mptcp_set_timeout(sk, tout);
1469 
1470 	/* pick the best backup if no other subflow is active */
1471 	if (!nr_active)
1472 		send_info[SSK_MODE_ACTIVE].ssk = send_info[SSK_MODE_BACKUP].ssk;
1473 
1474 	/* According to the blest algorithm, to avoid HoL blocking for the
1475 	 * faster flow, we need to:
1476 	 * - estimate the faster flow linger time
1477 	 * - use the above to estimate the amount of byte transferred
1478 	 *   by the faster flow
1479 	 * - check that the amount of queued data is greter than the above,
1480 	 *   otherwise do not use the picked, slower, subflow
1481 	 * We select the subflow with the shorter estimated time to flush
1482 	 * the queued mem, which basically ensure the above. We just need
1483 	 * to check that subflow has a non empty cwin.
1484 	 */
1485 	ssk = send_info[SSK_MODE_ACTIVE].ssk;
1486 	if (!ssk || !sk_stream_memory_free(ssk))
1487 		return NULL;
1488 
1489 	burst = min_t(int, MPTCP_SEND_BURST_SIZE, mptcp_wnd_end(msk) - msk->snd_nxt);
1490 	wmem = READ_ONCE(ssk->sk_wmem_queued);
1491 	if (!burst)
1492 		return ssk;
1493 
1494 	subflow = mptcp_subflow_ctx(ssk);
1495 	subflow->avg_pacing_rate = div_u64((u64)subflow->avg_pacing_rate * wmem +
1496 					   READ_ONCE(ssk->sk_pacing_rate) * burst,
1497 					   burst + wmem);
1498 	msk->snd_burst = burst;
1499 	return ssk;
1500 }
1501 
mptcp_push_release(struct sock * ssk,struct mptcp_sendmsg_info * info)1502 static void mptcp_push_release(struct sock *ssk, struct mptcp_sendmsg_info *info)
1503 {
1504 	tcp_push(ssk, 0, info->mss_now, tcp_sk(ssk)->nonagle, info->size_goal);
1505 	release_sock(ssk);
1506 }
1507 
mptcp_update_post_push(struct mptcp_sock * msk,struct mptcp_data_frag * dfrag,u32 sent)1508 static void mptcp_update_post_push(struct mptcp_sock *msk,
1509 				   struct mptcp_data_frag *dfrag,
1510 				   u32 sent)
1511 {
1512 	u64 snd_nxt_new = dfrag->data_seq;
1513 
1514 	dfrag->already_sent += sent;
1515 
1516 	msk->snd_burst -= sent;
1517 
1518 	snd_nxt_new += dfrag->already_sent;
1519 
1520 	/* snd_nxt_new can be smaller than snd_nxt in case mptcp
1521 	 * is recovering after a failover. In that event, this re-sends
1522 	 * old segments.
1523 	 *
1524 	 * Thus compute snd_nxt_new candidate based on
1525 	 * the dfrag->data_seq that was sent and the data
1526 	 * that has been handed to the subflow for transmission
1527 	 * and skip update in case it was old dfrag.
1528 	 */
1529 	if (likely(after64(snd_nxt_new, msk->snd_nxt))) {
1530 		msk->bytes_sent += snd_nxt_new - msk->snd_nxt;
1531 		WRITE_ONCE(msk->snd_nxt, snd_nxt_new);
1532 	}
1533 }
1534 
mptcp_check_and_set_pending(struct sock * sk)1535 void mptcp_check_and_set_pending(struct sock *sk)
1536 {
1537 	if (mptcp_send_head(sk)) {
1538 		mptcp_data_lock(sk);
1539 		mptcp_sk(sk)->cb_flags |= BIT(MPTCP_PUSH_PENDING);
1540 		mptcp_data_unlock(sk);
1541 	}
1542 }
1543 
__subflow_push_pending(struct sock * sk,struct sock * ssk,struct mptcp_sendmsg_info * info)1544 static int __subflow_push_pending(struct sock *sk, struct sock *ssk,
1545 				  struct mptcp_sendmsg_info *info)
1546 {
1547 	struct mptcp_sock *msk = mptcp_sk(sk);
1548 	struct mptcp_data_frag *dfrag;
1549 	int len, copied = 0, err = 0;
1550 
1551 	while ((dfrag = mptcp_send_head(sk))) {
1552 		info->sent = dfrag->already_sent;
1553 		info->limit = dfrag->data_len;
1554 		len = dfrag->data_len - dfrag->already_sent;
1555 		while (len > 0) {
1556 			int ret = 0;
1557 
1558 			ret = mptcp_sendmsg_frag(sk, ssk, dfrag, info);
1559 			if (ret <= 0) {
1560 				err = copied ? : ret;
1561 				goto out;
1562 			}
1563 
1564 			info->sent += ret;
1565 			copied += ret;
1566 			len -= ret;
1567 
1568 			mptcp_update_post_push(msk, dfrag, ret);
1569 		}
1570 		WRITE_ONCE(msk->first_pending, mptcp_send_next(sk));
1571 
1572 		if (msk->snd_burst <= 0 ||
1573 		    !sk_stream_memory_free(ssk) ||
1574 		    !mptcp_subflow_active(mptcp_subflow_ctx(ssk))) {
1575 			err = copied;
1576 			goto out;
1577 		}
1578 		mptcp_set_timeout(sk);
1579 	}
1580 	err = copied;
1581 
1582 out:
1583 	if (err > 0)
1584 		msk->last_data_sent = tcp_jiffies32;
1585 	return err;
1586 }
1587 
__mptcp_push_pending(struct sock * sk,unsigned int flags)1588 void __mptcp_push_pending(struct sock *sk, unsigned int flags)
1589 {
1590 	struct sock *prev_ssk = NULL, *ssk = NULL;
1591 	struct mptcp_sock *msk = mptcp_sk(sk);
1592 	struct mptcp_sendmsg_info info = {
1593 				.flags = flags,
1594 	};
1595 	bool do_check_data_fin = false;
1596 	int push_count = 1;
1597 
1598 	while (mptcp_send_head(sk) && (push_count > 0)) {
1599 		struct mptcp_subflow_context *subflow;
1600 		int ret = 0;
1601 
1602 		if (mptcp_sched_get_send(msk))
1603 			break;
1604 
1605 		push_count = 0;
1606 
1607 		mptcp_for_each_subflow(msk, subflow) {
1608 			if (READ_ONCE(subflow->scheduled)) {
1609 				mptcp_subflow_set_scheduled(subflow, false);
1610 
1611 				prev_ssk = ssk;
1612 				ssk = mptcp_subflow_tcp_sock(subflow);
1613 				if (ssk != prev_ssk) {
1614 					/* First check. If the ssk has changed since
1615 					 * the last round, release prev_ssk
1616 					 */
1617 					if (prev_ssk)
1618 						mptcp_push_release(prev_ssk, &info);
1619 
1620 					/* Need to lock the new subflow only if different
1621 					 * from the previous one, otherwise we are still
1622 					 * helding the relevant lock
1623 					 */
1624 					lock_sock(ssk);
1625 				}
1626 
1627 				push_count++;
1628 
1629 				ret = __subflow_push_pending(sk, ssk, &info);
1630 				if (ret <= 0) {
1631 					if (ret != -EAGAIN ||
1632 					    (1 << ssk->sk_state) &
1633 					     (TCPF_FIN_WAIT1 | TCPF_FIN_WAIT2 | TCPF_CLOSE))
1634 						push_count--;
1635 					continue;
1636 				}
1637 				do_check_data_fin = true;
1638 			}
1639 		}
1640 	}
1641 
1642 	/* at this point we held the socket lock for the last subflow we used */
1643 	if (ssk)
1644 		mptcp_push_release(ssk, &info);
1645 
1646 	/* ensure the rtx timer is running */
1647 	if (!mptcp_rtx_timer_pending(sk))
1648 		mptcp_reset_rtx_timer(sk);
1649 	if (do_check_data_fin)
1650 		mptcp_check_send_data_fin(sk);
1651 }
1652 
__mptcp_subflow_push_pending(struct sock * sk,struct sock * ssk,bool first)1653 static void __mptcp_subflow_push_pending(struct sock *sk, struct sock *ssk, bool first)
1654 {
1655 	struct mptcp_sock *msk = mptcp_sk(sk);
1656 	struct mptcp_sendmsg_info info = {
1657 		.data_lock_held = true,
1658 	};
1659 	bool keep_pushing = true;
1660 	struct sock *xmit_ssk;
1661 	int copied = 0;
1662 
1663 	info.flags = 0;
1664 	while (mptcp_send_head(sk) && keep_pushing) {
1665 		struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1666 		int ret = 0;
1667 
1668 		/* check for a different subflow usage only after
1669 		 * spooling the first chunk of data
1670 		 */
1671 		if (first) {
1672 			mptcp_subflow_set_scheduled(subflow, false);
1673 			ret = __subflow_push_pending(sk, ssk, &info);
1674 			first = false;
1675 			if (ret <= 0)
1676 				break;
1677 			copied += ret;
1678 			continue;
1679 		}
1680 
1681 		if (mptcp_sched_get_send(msk))
1682 			goto out;
1683 
1684 		if (READ_ONCE(subflow->scheduled)) {
1685 			mptcp_subflow_set_scheduled(subflow, false);
1686 			ret = __subflow_push_pending(sk, ssk, &info);
1687 			if (ret <= 0)
1688 				keep_pushing = false;
1689 			copied += ret;
1690 		}
1691 
1692 		mptcp_for_each_subflow(msk, subflow) {
1693 			if (READ_ONCE(subflow->scheduled)) {
1694 				xmit_ssk = mptcp_subflow_tcp_sock(subflow);
1695 				if (xmit_ssk != ssk) {
1696 					mptcp_subflow_delegate(subflow,
1697 							       MPTCP_DELEGATE_SEND);
1698 					keep_pushing = false;
1699 				}
1700 			}
1701 		}
1702 	}
1703 
1704 out:
1705 	/* __mptcp_alloc_tx_skb could have released some wmem and we are
1706 	 * not going to flush it via release_sock()
1707 	 */
1708 	if (copied) {
1709 		tcp_push(ssk, 0, info.mss_now, tcp_sk(ssk)->nonagle,
1710 			 info.size_goal);
1711 		if (!mptcp_rtx_timer_pending(sk))
1712 			mptcp_reset_rtx_timer(sk);
1713 
1714 		if (msk->snd_data_fin_enable &&
1715 		    msk->snd_nxt + 1 == msk->write_seq)
1716 			mptcp_schedule_work(sk);
1717 	}
1718 }
1719 
1720 static int mptcp_disconnect(struct sock *sk, int flags);
1721 
mptcp_sendmsg_fastopen(struct sock * sk,struct msghdr * msg,size_t len,int * copied_syn)1722 static int mptcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg,
1723 				  size_t len, int *copied_syn)
1724 {
1725 	unsigned int saved_flags = msg->msg_flags;
1726 	struct mptcp_sock *msk = mptcp_sk(sk);
1727 	struct sock *ssk;
1728 	int ret;
1729 
1730 	/* on flags based fastopen the mptcp is supposed to create the
1731 	 * first subflow right now. Otherwise we are in the defer_connect
1732 	 * path, and the first subflow must be already present.
1733 	 * Since the defer_connect flag is cleared after the first succsful
1734 	 * fastopen attempt, no need to check for additional subflow status.
1735 	 */
1736 	if (msg->msg_flags & MSG_FASTOPEN) {
1737 		ssk = __mptcp_nmpc_sk(msk);
1738 		if (IS_ERR(ssk))
1739 			return PTR_ERR(ssk);
1740 	}
1741 	if (!msk->first)
1742 		return -EINVAL;
1743 
1744 	ssk = msk->first;
1745 
1746 	lock_sock(ssk);
1747 	msg->msg_flags |= MSG_DONTWAIT;
1748 	msk->fastopening = 1;
1749 	ret = tcp_sendmsg_fastopen(ssk, msg, copied_syn, len, NULL);
1750 	msk->fastopening = 0;
1751 	msg->msg_flags = saved_flags;
1752 	release_sock(ssk);
1753 
1754 	/* do the blocking bits of inet_stream_connect outside the ssk socket lock */
1755 	if (ret == -EINPROGRESS && !(msg->msg_flags & MSG_DONTWAIT)) {
1756 		ret = __inet_stream_connect(sk->sk_socket, msg->msg_name,
1757 					    msg->msg_namelen, msg->msg_flags, 1);
1758 
1759 		/* Keep the same behaviour of plain TCP: zero the copied bytes in
1760 		 * case of any error, except timeout or signal
1761 		 */
1762 		if (ret && ret != -EINPROGRESS && ret != -ERESTARTSYS && ret != -EINTR)
1763 			*copied_syn = 0;
1764 	} else if (ret && ret != -EINPROGRESS) {
1765 		/* The disconnect() op called by tcp_sendmsg_fastopen()/
1766 		 * __inet_stream_connect() can fail, due to looking check,
1767 		 * see mptcp_disconnect().
1768 		 * Attempt it again outside the problematic scope.
1769 		 */
1770 		if (!mptcp_disconnect(sk, 0)) {
1771 			sk->sk_disconnects++;
1772 			sk->sk_socket->state = SS_UNCONNECTED;
1773 		}
1774 	}
1775 	inet_clear_bit(DEFER_CONNECT, sk);
1776 
1777 	return ret;
1778 }
1779 
do_copy_data_nocache(struct sock * sk,int copy,struct iov_iter * from,char * to)1780 static int do_copy_data_nocache(struct sock *sk, int copy,
1781 				struct iov_iter *from, char *to)
1782 {
1783 	if (sk->sk_route_caps & NETIF_F_NOCACHE_COPY) {
1784 		if (!copy_from_iter_full_nocache(to, copy, from))
1785 			return -EFAULT;
1786 	} else if (!copy_from_iter_full(to, copy, from)) {
1787 		return -EFAULT;
1788 	}
1789 	return 0;
1790 }
1791 
1792 /* open-code sk_stream_memory_free() plus sent limit computation to
1793  * avoid indirect calls in fast-path.
1794  * Called under the msk socket lock, so we can avoid a bunch of ONCE
1795  * annotations.
1796  */
mptcp_send_limit(const struct sock * sk)1797 static u32 mptcp_send_limit(const struct sock *sk)
1798 {
1799 	const struct mptcp_sock *msk = mptcp_sk(sk);
1800 	u32 limit, not_sent;
1801 
1802 	if (sk->sk_wmem_queued >= READ_ONCE(sk->sk_sndbuf))
1803 		return 0;
1804 
1805 	limit = mptcp_notsent_lowat(sk);
1806 	if (limit == UINT_MAX)
1807 		return UINT_MAX;
1808 
1809 	not_sent = msk->write_seq - msk->snd_nxt;
1810 	if (not_sent >= limit)
1811 		return 0;
1812 
1813 	return limit - not_sent;
1814 }
1815 
mptcp_sendmsg(struct sock * sk,struct msghdr * msg,size_t len)1816 static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
1817 {
1818 	struct mptcp_sock *msk = mptcp_sk(sk);
1819 	struct page_frag *pfrag;
1820 	size_t copied = 0;
1821 	int ret = 0;
1822 	long timeo;
1823 
1824 	/* silently ignore everything else */
1825 	msg->msg_flags &= MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL | MSG_FASTOPEN;
1826 
1827 	lock_sock(sk);
1828 
1829 	if (unlikely(inet_test_bit(DEFER_CONNECT, sk) ||
1830 		     msg->msg_flags & MSG_FASTOPEN)) {
1831 		int copied_syn = 0;
1832 
1833 		ret = mptcp_sendmsg_fastopen(sk, msg, len, &copied_syn);
1834 		copied += copied_syn;
1835 		if (ret == -EINPROGRESS && copied_syn > 0)
1836 			goto out;
1837 		else if (ret)
1838 			goto do_error;
1839 	}
1840 
1841 	timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
1842 
1843 	if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) {
1844 		ret = sk_stream_wait_connect(sk, &timeo);
1845 		if (ret)
1846 			goto do_error;
1847 	}
1848 
1849 	ret = -EPIPE;
1850 	if (unlikely(sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)))
1851 		goto do_error;
1852 
1853 	pfrag = sk_page_frag(sk);
1854 
1855 	while (msg_data_left(msg)) {
1856 		int total_ts, frag_truesize = 0;
1857 		struct mptcp_data_frag *dfrag;
1858 		bool dfrag_collapsed;
1859 		size_t psize, offset;
1860 		u32 copy_limit;
1861 
1862 		/* ensure fitting the notsent_lowat() constraint */
1863 		copy_limit = mptcp_send_limit(sk);
1864 		if (!copy_limit)
1865 			goto wait_for_memory;
1866 
1867 		/* reuse tail pfrag, if possible, or carve a new one from the
1868 		 * page allocator
1869 		 */
1870 		dfrag = mptcp_pending_tail(sk);
1871 		dfrag_collapsed = mptcp_frag_can_collapse_to(msk, pfrag, dfrag);
1872 		if (!dfrag_collapsed) {
1873 			if (!mptcp_page_frag_refill(sk, pfrag))
1874 				goto wait_for_memory;
1875 
1876 			dfrag = mptcp_carve_data_frag(msk, pfrag, pfrag->offset);
1877 			frag_truesize = dfrag->overhead;
1878 		}
1879 
1880 		/* we do not bound vs wspace, to allow a single packet.
1881 		 * memory accounting will prevent execessive memory usage
1882 		 * anyway
1883 		 */
1884 		offset = dfrag->offset + dfrag->data_len;
1885 		psize = pfrag->size - offset;
1886 		psize = min_t(size_t, psize, msg_data_left(msg));
1887 		psize = min_t(size_t, psize, copy_limit);
1888 		total_ts = psize + frag_truesize;
1889 
1890 		if (!sk_wmem_schedule(sk, total_ts))
1891 			goto wait_for_memory;
1892 
1893 		ret = do_copy_data_nocache(sk, psize, &msg->msg_iter,
1894 					   page_address(dfrag->page) + offset);
1895 		if (ret)
1896 			goto do_error;
1897 
1898 		/* data successfully copied into the write queue */
1899 		sk_forward_alloc_add(sk, -total_ts);
1900 		copied += psize;
1901 		dfrag->data_len += psize;
1902 		frag_truesize += psize;
1903 		pfrag->offset += frag_truesize;
1904 		WRITE_ONCE(msk->write_seq, msk->write_seq + psize);
1905 
1906 		/* charge data on mptcp pending queue to the msk socket
1907 		 * Note: we charge such data both to sk and ssk
1908 		 */
1909 		sk_wmem_queued_add(sk, frag_truesize);
1910 		if (!dfrag_collapsed) {
1911 			get_page(dfrag->page);
1912 			list_add_tail(&dfrag->list, &msk->rtx_queue);
1913 			if (!msk->first_pending)
1914 				WRITE_ONCE(msk->first_pending, dfrag);
1915 		}
1916 		pr_debug("msk=%p dfrag at seq=%llu len=%u sent=%u new=%d\n", msk,
1917 			 dfrag->data_seq, dfrag->data_len, dfrag->already_sent,
1918 			 !dfrag_collapsed);
1919 
1920 		continue;
1921 
1922 wait_for_memory:
1923 		set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
1924 		__mptcp_push_pending(sk, msg->msg_flags);
1925 		ret = sk_stream_wait_memory(sk, &timeo);
1926 		if (ret)
1927 			goto do_error;
1928 	}
1929 
1930 	if (copied)
1931 		__mptcp_push_pending(sk, msg->msg_flags);
1932 
1933 out:
1934 	release_sock(sk);
1935 	return copied;
1936 
1937 do_error:
1938 	if (copied)
1939 		goto out;
1940 
1941 	copied = sk_stream_error(sk, msg->msg_flags, ret);
1942 	goto out;
1943 }
1944 
1945 static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied);
1946 
__mptcp_recvmsg_mskq(struct mptcp_sock * msk,struct msghdr * msg,size_t len,int flags,struct scm_timestamping_internal * tss,int * cmsg_flags)1947 static int __mptcp_recvmsg_mskq(struct mptcp_sock *msk,
1948 				struct msghdr *msg,
1949 				size_t len, int flags,
1950 				struct scm_timestamping_internal *tss,
1951 				int *cmsg_flags)
1952 {
1953 	struct sk_buff *skb, *tmp;
1954 	int copied = 0;
1955 
1956 	skb_queue_walk_safe(&msk->receive_queue, skb, tmp) {
1957 		u32 offset = MPTCP_SKB_CB(skb)->offset;
1958 		u32 data_len = skb->len - offset;
1959 		u32 count = min_t(size_t, len - copied, data_len);
1960 		int err;
1961 
1962 		if (!(flags & MSG_TRUNC)) {
1963 			err = skb_copy_datagram_msg(skb, offset, msg, count);
1964 			if (unlikely(err < 0)) {
1965 				if (!copied)
1966 					return err;
1967 				break;
1968 			}
1969 		}
1970 
1971 		if (MPTCP_SKB_CB(skb)->has_rxtstamp) {
1972 			tcp_update_recv_tstamps(skb, tss);
1973 			*cmsg_flags |= MPTCP_CMSG_TS;
1974 		}
1975 
1976 		copied += count;
1977 
1978 		if (count < data_len) {
1979 			if (!(flags & MSG_PEEK)) {
1980 				MPTCP_SKB_CB(skb)->offset += count;
1981 				MPTCP_SKB_CB(skb)->map_seq += count;
1982 				msk->bytes_consumed += count;
1983 			}
1984 			break;
1985 		}
1986 
1987 		if (!(flags & MSG_PEEK)) {
1988 			/* we will bulk release the skb memory later */
1989 			skb->destructor = NULL;
1990 			WRITE_ONCE(msk->rmem_released, msk->rmem_released + skb->truesize);
1991 			__skb_unlink(skb, &msk->receive_queue);
1992 			__kfree_skb(skb);
1993 			msk->bytes_consumed += count;
1994 		}
1995 
1996 		if (copied >= len)
1997 			break;
1998 	}
1999 
2000 	mptcp_rcv_space_adjust(msk, copied);
2001 	return copied;
2002 }
2003 
2004 /* receive buffer autotuning.  See tcp_rcv_space_adjust for more information.
2005  *
2006  * Only difference: Use highest rtt estimate of the subflows in use.
2007  */
mptcp_rcv_space_adjust(struct mptcp_sock * msk,int copied)2008 static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied)
2009 {
2010 	struct mptcp_subflow_context *subflow;
2011 	struct sock *sk = (struct sock *)msk;
2012 	u8 scaling_ratio = U8_MAX;
2013 	u32 time, advmss = 1;
2014 	u64 rtt_us, mstamp;
2015 
2016 	msk_owned_by_me(msk);
2017 
2018 	if (copied <= 0)
2019 		return;
2020 
2021 	if (!msk->rcvspace_init)
2022 		mptcp_rcv_space_init(msk, msk->first);
2023 
2024 	msk->rcvq_space.copied += copied;
2025 
2026 	mstamp = div_u64(tcp_clock_ns(), NSEC_PER_USEC);
2027 	time = tcp_stamp_us_delta(mstamp, msk->rcvq_space.time);
2028 
2029 	rtt_us = msk->rcvq_space.rtt_us;
2030 	if (rtt_us && time < (rtt_us >> 3))
2031 		return;
2032 
2033 	rtt_us = 0;
2034 	mptcp_for_each_subflow(msk, subflow) {
2035 		const struct tcp_sock *tp;
2036 		u64 sf_rtt_us;
2037 		u32 sf_advmss;
2038 
2039 		tp = tcp_sk(mptcp_subflow_tcp_sock(subflow));
2040 
2041 		sf_rtt_us = READ_ONCE(tp->rcv_rtt_est.rtt_us);
2042 		sf_advmss = READ_ONCE(tp->advmss);
2043 
2044 		rtt_us = max(sf_rtt_us, rtt_us);
2045 		advmss = max(sf_advmss, advmss);
2046 		scaling_ratio = min(tp->scaling_ratio, scaling_ratio);
2047 	}
2048 
2049 	msk->rcvq_space.rtt_us = rtt_us;
2050 	msk->scaling_ratio = scaling_ratio;
2051 	if (time < (rtt_us >> 3) || rtt_us == 0)
2052 		return;
2053 
2054 	if (msk->rcvq_space.copied <= msk->rcvq_space.space)
2055 		goto new_measure;
2056 
2057 	if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_moderate_rcvbuf) &&
2058 	    !(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
2059 		u64 rcvwin, grow;
2060 		int rcvbuf;
2061 
2062 		rcvwin = ((u64)msk->rcvq_space.copied << 1) + 16 * advmss;
2063 
2064 		grow = rcvwin * (msk->rcvq_space.copied - msk->rcvq_space.space);
2065 
2066 		do_div(grow, msk->rcvq_space.space);
2067 		rcvwin += (grow << 1);
2068 
2069 		rcvbuf = min_t(u64, mptcp_space_from_win(sk, rcvwin),
2070 			       READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[2]));
2071 
2072 		if (rcvbuf > sk->sk_rcvbuf) {
2073 			u32 window_clamp;
2074 
2075 			window_clamp = mptcp_win_from_space(sk, rcvbuf);
2076 			WRITE_ONCE(sk->sk_rcvbuf, rcvbuf);
2077 
2078 			/* Make subflows follow along.  If we do not do this, we
2079 			 * get drops at subflow level if skbs can't be moved to
2080 			 * the mptcp rx queue fast enough (announced rcv_win can
2081 			 * exceed ssk->sk_rcvbuf).
2082 			 */
2083 			mptcp_for_each_subflow(msk, subflow) {
2084 				struct sock *ssk;
2085 				bool slow;
2086 
2087 				ssk = mptcp_subflow_tcp_sock(subflow);
2088 				slow = lock_sock_fast(ssk);
2089 				WRITE_ONCE(ssk->sk_rcvbuf, rcvbuf);
2090 				WRITE_ONCE(tcp_sk(ssk)->window_clamp, window_clamp);
2091 				if (tcp_can_send_ack(ssk))
2092 					tcp_cleanup_rbuf(ssk, 1);
2093 				unlock_sock_fast(ssk, slow);
2094 			}
2095 		}
2096 	}
2097 
2098 	msk->rcvq_space.space = msk->rcvq_space.copied;
2099 new_measure:
2100 	msk->rcvq_space.copied = 0;
2101 	msk->rcvq_space.time = mstamp;
2102 }
2103 
__mptcp_update_rmem(struct sock * sk)2104 static void __mptcp_update_rmem(struct sock *sk)
2105 {
2106 	struct mptcp_sock *msk = mptcp_sk(sk);
2107 
2108 	if (!msk->rmem_released)
2109 		return;
2110 
2111 	atomic_sub(msk->rmem_released, &sk->sk_rmem_alloc);
2112 	mptcp_rmem_uncharge(sk, msk->rmem_released);
2113 	WRITE_ONCE(msk->rmem_released, 0);
2114 }
2115 
__mptcp_splice_receive_queue(struct sock * sk)2116 static void __mptcp_splice_receive_queue(struct sock *sk)
2117 {
2118 	struct mptcp_sock *msk = mptcp_sk(sk);
2119 
2120 	skb_queue_splice_tail_init(&sk->sk_receive_queue, &msk->receive_queue);
2121 }
2122 
__mptcp_move_skbs(struct mptcp_sock * msk)2123 static bool __mptcp_move_skbs(struct mptcp_sock *msk)
2124 {
2125 	struct sock *sk = (struct sock *)msk;
2126 	unsigned int moved = 0;
2127 	bool ret, done;
2128 
2129 	do {
2130 		struct sock *ssk = mptcp_subflow_recv_lookup(msk);
2131 		bool slowpath;
2132 
2133 		/* we can have data pending in the subflows only if the msk
2134 		 * receive buffer was full at subflow_data_ready() time,
2135 		 * that is an unlikely slow path.
2136 		 */
2137 		if (likely(!ssk))
2138 			break;
2139 
2140 		slowpath = lock_sock_fast(ssk);
2141 		mptcp_data_lock(sk);
2142 		__mptcp_update_rmem(sk);
2143 		done = __mptcp_move_skbs_from_subflow(msk, ssk, &moved);
2144 		mptcp_data_unlock(sk);
2145 
2146 		if (unlikely(ssk->sk_err))
2147 			__mptcp_error_report(sk);
2148 		unlock_sock_fast(ssk, slowpath);
2149 	} while (!done);
2150 
2151 	/* acquire the data lock only if some input data is pending */
2152 	ret = moved > 0;
2153 	if (!RB_EMPTY_ROOT(&msk->out_of_order_queue) ||
2154 	    !skb_queue_empty_lockless(&sk->sk_receive_queue)) {
2155 		mptcp_data_lock(sk);
2156 		__mptcp_update_rmem(sk);
2157 		ret |= __mptcp_ofo_queue(msk);
2158 		__mptcp_splice_receive_queue(sk);
2159 		mptcp_data_unlock(sk);
2160 	}
2161 	if (ret)
2162 		mptcp_check_data_fin((struct sock *)msk);
2163 	return !skb_queue_empty(&msk->receive_queue);
2164 }
2165 
mptcp_inq_hint(const struct sock * sk)2166 static unsigned int mptcp_inq_hint(const struct sock *sk)
2167 {
2168 	const struct mptcp_sock *msk = mptcp_sk(sk);
2169 	const struct sk_buff *skb;
2170 
2171 	skb = skb_peek(&msk->receive_queue);
2172 	if (skb) {
2173 		u64 hint_val = READ_ONCE(msk->ack_seq) - MPTCP_SKB_CB(skb)->map_seq;
2174 
2175 		if (hint_val >= INT_MAX)
2176 			return INT_MAX;
2177 
2178 		return (unsigned int)hint_val;
2179 	}
2180 
2181 	if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
2182 		return 1;
2183 
2184 	return 0;
2185 }
2186 
mptcp_recvmsg(struct sock * sk,struct msghdr * msg,size_t len,int flags,int * addr_len)2187 static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
2188 			 int flags, int *addr_len)
2189 {
2190 	struct mptcp_sock *msk = mptcp_sk(sk);
2191 	struct scm_timestamping_internal tss;
2192 	int copied = 0, cmsg_flags = 0;
2193 	int target;
2194 	long timeo;
2195 
2196 	/* MSG_ERRQUEUE is really a no-op till we support IP_RECVERR */
2197 	if (unlikely(flags & MSG_ERRQUEUE))
2198 		return inet_recv_error(sk, msg, len, addr_len);
2199 
2200 	lock_sock(sk);
2201 	if (unlikely(sk->sk_state == TCP_LISTEN)) {
2202 		copied = -ENOTCONN;
2203 		goto out_err;
2204 	}
2205 
2206 	timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
2207 
2208 	len = min_t(size_t, len, INT_MAX);
2209 	target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
2210 
2211 	if (unlikely(msk->recvmsg_inq))
2212 		cmsg_flags = MPTCP_CMSG_INQ;
2213 
2214 	while (copied < len) {
2215 		int err, bytes_read;
2216 
2217 		bytes_read = __mptcp_recvmsg_mskq(msk, msg, len - copied, flags, &tss, &cmsg_flags);
2218 		if (unlikely(bytes_read < 0)) {
2219 			if (!copied)
2220 				copied = bytes_read;
2221 			goto out_err;
2222 		}
2223 
2224 		copied += bytes_read;
2225 
2226 		if (skb_queue_empty(&msk->receive_queue) && __mptcp_move_skbs(msk))
2227 			continue;
2228 
2229 		/* only the MPTCP socket status is relevant here. The exit
2230 		 * conditions mirror closely tcp_recvmsg()
2231 		 */
2232 		if (copied >= target)
2233 			break;
2234 
2235 		if (copied) {
2236 			if (sk->sk_err ||
2237 			    sk->sk_state == TCP_CLOSE ||
2238 			    (sk->sk_shutdown & RCV_SHUTDOWN) ||
2239 			    !timeo ||
2240 			    signal_pending(current))
2241 				break;
2242 		} else {
2243 			if (sk->sk_err) {
2244 				copied = sock_error(sk);
2245 				break;
2246 			}
2247 
2248 			if (sk->sk_shutdown & RCV_SHUTDOWN) {
2249 				/* race breaker: the shutdown could be after the
2250 				 * previous receive queue check
2251 				 */
2252 				if (__mptcp_move_skbs(msk))
2253 					continue;
2254 				break;
2255 			}
2256 
2257 			if (sk->sk_state == TCP_CLOSE) {
2258 				copied = -ENOTCONN;
2259 				break;
2260 			}
2261 
2262 			if (!timeo) {
2263 				copied = -EAGAIN;
2264 				break;
2265 			}
2266 
2267 			if (signal_pending(current)) {
2268 				copied = sock_intr_errno(timeo);
2269 				break;
2270 			}
2271 		}
2272 
2273 		pr_debug("block timeout %ld\n", timeo);
2274 		mptcp_cleanup_rbuf(msk, copied);
2275 		err = sk_wait_data(sk, &timeo, NULL);
2276 		if (err < 0) {
2277 			err = copied ? : err;
2278 			goto out_err;
2279 		}
2280 	}
2281 
2282 	mptcp_cleanup_rbuf(msk, copied);
2283 
2284 out_err:
2285 	if (cmsg_flags && copied >= 0) {
2286 		if (cmsg_flags & MPTCP_CMSG_TS)
2287 			tcp_recv_timestamp(msg, sk, &tss);
2288 
2289 		if (cmsg_flags & MPTCP_CMSG_INQ) {
2290 			unsigned int inq = mptcp_inq_hint(sk);
2291 
2292 			put_cmsg(msg, SOL_TCP, TCP_CM_INQ, sizeof(inq), &inq);
2293 		}
2294 	}
2295 
2296 	pr_debug("msk=%p rx queue empty=%d:%d copied=%d\n",
2297 		 msk, skb_queue_empty_lockless(&sk->sk_receive_queue),
2298 		 skb_queue_empty(&msk->receive_queue), copied);
2299 
2300 	release_sock(sk);
2301 	return copied;
2302 }
2303 
mptcp_retransmit_timer(struct timer_list * t)2304 static void mptcp_retransmit_timer(struct timer_list *t)
2305 {
2306 	struct inet_connection_sock *icsk = from_timer(icsk, t,
2307 						       icsk_retransmit_timer);
2308 	struct sock *sk = &icsk->icsk_inet.sk;
2309 	struct mptcp_sock *msk = mptcp_sk(sk);
2310 
2311 	bh_lock_sock(sk);
2312 	if (!sock_owned_by_user(sk)) {
2313 		/* we need a process context to retransmit */
2314 		if (!test_and_set_bit(MPTCP_WORK_RTX, &msk->flags))
2315 			mptcp_schedule_work(sk);
2316 	} else {
2317 		/* delegate our work to tcp_release_cb() */
2318 		__set_bit(MPTCP_RETRANSMIT, &msk->cb_flags);
2319 	}
2320 	bh_unlock_sock(sk);
2321 	sock_put(sk);
2322 }
2323 
mptcp_tout_timer(struct timer_list * t)2324 static void mptcp_tout_timer(struct timer_list *t)
2325 {
2326 	struct sock *sk = from_timer(sk, t, sk_timer);
2327 
2328 	mptcp_schedule_work(sk);
2329 	sock_put(sk);
2330 }
2331 
2332 /* Find an idle subflow.  Return NULL if there is unacked data at tcp
2333  * level.
2334  *
2335  * A backup subflow is returned only if that is the only kind available.
2336  */
mptcp_subflow_get_retrans(struct mptcp_sock * msk)2337 struct sock *mptcp_subflow_get_retrans(struct mptcp_sock *msk)
2338 {
2339 	struct sock *backup = NULL, *pick = NULL;
2340 	struct mptcp_subflow_context *subflow;
2341 	int min_stale_count = INT_MAX;
2342 
2343 	mptcp_for_each_subflow(msk, subflow) {
2344 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
2345 
2346 		if (!__mptcp_subflow_active(subflow))
2347 			continue;
2348 
2349 		/* still data outstanding at TCP level? skip this */
2350 		if (!tcp_rtx_and_write_queues_empty(ssk)) {
2351 			mptcp_pm_subflow_chk_stale(msk, ssk);
2352 			min_stale_count = min_t(int, min_stale_count, subflow->stale_count);
2353 			continue;
2354 		}
2355 
2356 		if (subflow->backup || subflow->request_bkup) {
2357 			if (!backup)
2358 				backup = ssk;
2359 			continue;
2360 		}
2361 
2362 		if (!pick)
2363 			pick = ssk;
2364 	}
2365 
2366 	if (pick)
2367 		return pick;
2368 
2369 	/* use backup only if there are no progresses anywhere */
2370 	return min_stale_count > 1 ? backup : NULL;
2371 }
2372 
__mptcp_retransmit_pending_data(struct sock * sk)2373 bool __mptcp_retransmit_pending_data(struct sock *sk)
2374 {
2375 	struct mptcp_data_frag *cur, *rtx_head;
2376 	struct mptcp_sock *msk = mptcp_sk(sk);
2377 
2378 	if (__mptcp_check_fallback(msk))
2379 		return false;
2380 
2381 	/* the closing socket has some data untransmitted and/or unacked:
2382 	 * some data in the mptcp rtx queue has not really xmitted yet.
2383 	 * keep it simple and re-inject the whole mptcp level rtx queue
2384 	 */
2385 	mptcp_data_lock(sk);
2386 	__mptcp_clean_una_wakeup(sk);
2387 	rtx_head = mptcp_rtx_head(sk);
2388 	if (!rtx_head) {
2389 		mptcp_data_unlock(sk);
2390 		return false;
2391 	}
2392 
2393 	msk->recovery_snd_nxt = msk->snd_nxt;
2394 	msk->recovery = true;
2395 	mptcp_data_unlock(sk);
2396 
2397 	msk->first_pending = rtx_head;
2398 	msk->snd_burst = 0;
2399 
2400 	/* be sure to clear the "sent status" on all re-injected fragments */
2401 	list_for_each_entry(cur, &msk->rtx_queue, list) {
2402 		if (!cur->already_sent)
2403 			break;
2404 		cur->already_sent = 0;
2405 	}
2406 
2407 	return true;
2408 }
2409 
2410 /* flags for __mptcp_close_ssk() */
2411 #define MPTCP_CF_PUSH		BIT(1)
2412 #define MPTCP_CF_FASTCLOSE	BIT(2)
2413 
2414 /* be sure to send a reset only if the caller asked for it, also
2415  * clean completely the subflow status when the subflow reaches
2416  * TCP_CLOSE state
2417  */
__mptcp_subflow_disconnect(struct sock * ssk,struct mptcp_subflow_context * subflow,unsigned int flags)2418 static void __mptcp_subflow_disconnect(struct sock *ssk,
2419 				       struct mptcp_subflow_context *subflow,
2420 				       unsigned int flags)
2421 {
2422 	if (((1 << ssk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) ||
2423 	    (flags & MPTCP_CF_FASTCLOSE)) {
2424 		/* The MPTCP code never wait on the subflow sockets, TCP-level
2425 		 * disconnect should never fail
2426 		 */
2427 		WARN_ON_ONCE(tcp_disconnect(ssk, 0));
2428 		mptcp_subflow_ctx_reset(subflow);
2429 	} else {
2430 		tcp_shutdown(ssk, SEND_SHUTDOWN);
2431 	}
2432 }
2433 
2434 /* subflow sockets can be either outgoing (connect) or incoming
2435  * (accept).
2436  *
2437  * Outgoing subflows use in-kernel sockets.
2438  * Incoming subflows do not have their own 'struct socket' allocated,
2439  * so we need to use tcp_close() after detaching them from the mptcp
2440  * parent socket.
2441  */
__mptcp_close_ssk(struct sock * sk,struct sock * ssk,struct mptcp_subflow_context * subflow,unsigned int flags)2442 static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
2443 			      struct mptcp_subflow_context *subflow,
2444 			      unsigned int flags)
2445 {
2446 	struct mptcp_sock *msk = mptcp_sk(sk);
2447 	bool dispose_it, need_push = false;
2448 
2449 	/* If the first subflow moved to a close state before accept, e.g. due
2450 	 * to an incoming reset or listener shutdown, the subflow socket is
2451 	 * already deleted by inet_child_forget() and the mptcp socket can't
2452 	 * survive too.
2453 	 */
2454 	if (msk->in_accept_queue && msk->first == ssk &&
2455 	    (sock_flag(sk, SOCK_DEAD) || sock_flag(ssk, SOCK_DEAD))) {
2456 		/* ensure later check in mptcp_worker() will dispose the msk */
2457 		sock_set_flag(sk, SOCK_DEAD);
2458 		mptcp_set_close_tout(sk, tcp_jiffies32 - (mptcp_close_timeout(sk) + 1));
2459 		lock_sock_nested(ssk, SINGLE_DEPTH_NESTING);
2460 		mptcp_subflow_drop_ctx(ssk);
2461 		goto out_release;
2462 	}
2463 
2464 	dispose_it = msk->free_first || ssk != msk->first;
2465 	if (dispose_it)
2466 		list_del(&subflow->node);
2467 
2468 	lock_sock_nested(ssk, SINGLE_DEPTH_NESTING);
2469 
2470 	if ((flags & MPTCP_CF_FASTCLOSE) && !__mptcp_check_fallback(msk)) {
2471 		/* be sure to force the tcp_close path
2472 		 * to generate the egress reset
2473 		 */
2474 		ssk->sk_lingertime = 0;
2475 		sock_set_flag(ssk, SOCK_LINGER);
2476 		subflow->send_fastclose = 1;
2477 	}
2478 
2479 	need_push = (flags & MPTCP_CF_PUSH) && __mptcp_retransmit_pending_data(sk);
2480 	if (!dispose_it) {
2481 		__mptcp_subflow_disconnect(ssk, subflow, flags);
2482 		release_sock(ssk);
2483 
2484 		goto out;
2485 	}
2486 
2487 	subflow->disposable = 1;
2488 
2489 	/* if ssk hit tcp_done(), tcp_cleanup_ulp() cleared the related ops
2490 	 * the ssk has been already destroyed, we just need to release the
2491 	 * reference owned by msk;
2492 	 */
2493 	if (!inet_csk(ssk)->icsk_ulp_ops) {
2494 		WARN_ON_ONCE(!sock_flag(ssk, SOCK_DEAD));
2495 		kfree_rcu(subflow, rcu);
2496 	} else {
2497 		/* otherwise tcp will dispose of the ssk and subflow ctx */
2498 		__tcp_close(ssk, 0);
2499 
2500 		/* close acquired an extra ref */
2501 		__sock_put(ssk);
2502 	}
2503 
2504 out_release:
2505 	__mptcp_subflow_error_report(sk, ssk);
2506 	release_sock(ssk);
2507 
2508 	sock_put(ssk);
2509 
2510 	if (ssk == msk->first)
2511 		WRITE_ONCE(msk->first, NULL);
2512 
2513 out:
2514 	__mptcp_sync_sndbuf(sk);
2515 	if (need_push)
2516 		__mptcp_push_pending(sk, 0);
2517 
2518 	/* Catch every 'all subflows closed' scenario, including peers silently
2519 	 * closing them, e.g. due to timeout.
2520 	 * For established sockets, allow an additional timeout before closing,
2521 	 * as the protocol can still create more subflows.
2522 	 */
2523 	if (list_is_singular(&msk->conn_list) && msk->first &&
2524 	    inet_sk_state_load(msk->first) == TCP_CLOSE) {
2525 		if (sk->sk_state != TCP_ESTABLISHED ||
2526 		    msk->in_accept_queue || sock_flag(sk, SOCK_DEAD)) {
2527 			mptcp_set_state(sk, TCP_CLOSE);
2528 			mptcp_close_wake_up(sk);
2529 		} else {
2530 			mptcp_start_tout_timer(sk);
2531 		}
2532 	}
2533 }
2534 
mptcp_close_ssk(struct sock * sk,struct sock * ssk,struct mptcp_subflow_context * subflow)2535 void mptcp_close_ssk(struct sock *sk, struct sock *ssk,
2536 		     struct mptcp_subflow_context *subflow)
2537 {
2538 	/* The first subflow can already be closed and still in the list */
2539 	if (subflow->close_event_done)
2540 		return;
2541 
2542 	subflow->close_event_done = true;
2543 
2544 	if (sk->sk_state == TCP_ESTABLISHED)
2545 		mptcp_event(MPTCP_EVENT_SUB_CLOSED, mptcp_sk(sk), ssk, GFP_KERNEL);
2546 
2547 	/* subflow aborted before reaching the fully_established status
2548 	 * attempt the creation of the next subflow
2549 	 */
2550 	mptcp_pm_subflow_check_next(mptcp_sk(sk), subflow);
2551 
2552 	__mptcp_close_ssk(sk, ssk, subflow, MPTCP_CF_PUSH);
2553 }
2554 
mptcp_sync_mss(struct sock * sk,u32 pmtu)2555 static unsigned int mptcp_sync_mss(struct sock *sk, u32 pmtu)
2556 {
2557 	return 0;
2558 }
2559 
__mptcp_close_subflow(struct sock * sk)2560 static void __mptcp_close_subflow(struct sock *sk)
2561 {
2562 	struct mptcp_subflow_context *subflow, *tmp;
2563 	struct mptcp_sock *msk = mptcp_sk(sk);
2564 
2565 	might_sleep();
2566 
2567 	mptcp_for_each_subflow_safe(msk, subflow, tmp) {
2568 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
2569 		int ssk_state = inet_sk_state_load(ssk);
2570 
2571 		if (ssk_state != TCP_CLOSE &&
2572 		    (ssk_state != TCP_CLOSE_WAIT ||
2573 		     inet_sk_state_load(sk) != TCP_ESTABLISHED))
2574 			continue;
2575 
2576 		/* 'subflow_data_ready' will re-sched once rx queue is empty */
2577 		if (!skb_queue_empty_lockless(&ssk->sk_receive_queue))
2578 			continue;
2579 
2580 		mptcp_close_ssk(sk, ssk, subflow);
2581 	}
2582 
2583 }
2584 
mptcp_close_tout_expired(const struct sock * sk)2585 static bool mptcp_close_tout_expired(const struct sock *sk)
2586 {
2587 	if (!inet_csk(sk)->icsk_mtup.probe_timestamp ||
2588 	    sk->sk_state == TCP_CLOSE)
2589 		return false;
2590 
2591 	return time_after32(tcp_jiffies32,
2592 		  inet_csk(sk)->icsk_mtup.probe_timestamp + mptcp_close_timeout(sk));
2593 }
2594 
mptcp_check_fastclose(struct mptcp_sock * msk)2595 static void mptcp_check_fastclose(struct mptcp_sock *msk)
2596 {
2597 	struct mptcp_subflow_context *subflow, *tmp;
2598 	struct sock *sk = (struct sock *)msk;
2599 
2600 	if (likely(!READ_ONCE(msk->rcv_fastclose)))
2601 		return;
2602 
2603 	mptcp_token_destroy(msk);
2604 
2605 	mptcp_for_each_subflow_safe(msk, subflow, tmp) {
2606 		struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow);
2607 		bool slow;
2608 
2609 		slow = lock_sock_fast(tcp_sk);
2610 		if (tcp_sk->sk_state != TCP_CLOSE) {
2611 			mptcp_send_active_reset_reason(tcp_sk);
2612 			tcp_set_state(tcp_sk, TCP_CLOSE);
2613 		}
2614 		unlock_sock_fast(tcp_sk, slow);
2615 	}
2616 
2617 	/* Mirror the tcp_reset() error propagation */
2618 	switch (sk->sk_state) {
2619 	case TCP_SYN_SENT:
2620 		WRITE_ONCE(sk->sk_err, ECONNREFUSED);
2621 		break;
2622 	case TCP_CLOSE_WAIT:
2623 		WRITE_ONCE(sk->sk_err, EPIPE);
2624 		break;
2625 	case TCP_CLOSE:
2626 		return;
2627 	default:
2628 		WRITE_ONCE(sk->sk_err, ECONNRESET);
2629 	}
2630 
2631 	mptcp_set_state(sk, TCP_CLOSE);
2632 	WRITE_ONCE(sk->sk_shutdown, SHUTDOWN_MASK);
2633 	smp_mb__before_atomic(); /* SHUTDOWN must be visible first */
2634 	set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags);
2635 
2636 	/* the calling mptcp_worker will properly destroy the socket */
2637 	if (sock_flag(sk, SOCK_DEAD))
2638 		return;
2639 
2640 	sk->sk_state_change(sk);
2641 	sk_error_report(sk);
2642 }
2643 
__mptcp_retrans(struct sock * sk)2644 static void __mptcp_retrans(struct sock *sk)
2645 {
2646 	struct mptcp_sock *msk = mptcp_sk(sk);
2647 	struct mptcp_subflow_context *subflow;
2648 	struct mptcp_sendmsg_info info = {};
2649 	struct mptcp_data_frag *dfrag;
2650 	struct sock *ssk;
2651 	int ret, err;
2652 	u16 len = 0;
2653 
2654 	mptcp_clean_una_wakeup(sk);
2655 
2656 	/* first check ssk: need to kick "stale" logic */
2657 	err = mptcp_sched_get_retrans(msk);
2658 	dfrag = mptcp_rtx_head(sk);
2659 	if (!dfrag) {
2660 		if (mptcp_data_fin_enabled(msk)) {
2661 			struct inet_connection_sock *icsk = inet_csk(sk);
2662 
2663 			icsk->icsk_retransmits++;
2664 			mptcp_set_datafin_timeout(sk);
2665 			mptcp_send_ack(msk);
2666 
2667 			goto reset_timer;
2668 		}
2669 
2670 		if (!mptcp_send_head(sk))
2671 			return;
2672 
2673 		goto reset_timer;
2674 	}
2675 
2676 	if (err)
2677 		goto reset_timer;
2678 
2679 	mptcp_for_each_subflow(msk, subflow) {
2680 		if (READ_ONCE(subflow->scheduled)) {
2681 			u16 copied = 0;
2682 
2683 			mptcp_subflow_set_scheduled(subflow, false);
2684 
2685 			ssk = mptcp_subflow_tcp_sock(subflow);
2686 
2687 			lock_sock(ssk);
2688 
2689 			/* limit retransmission to the bytes already sent on some subflows */
2690 			info.sent = 0;
2691 			info.limit = READ_ONCE(msk->csum_enabled) ? dfrag->data_len :
2692 								    dfrag->already_sent;
2693 			while (info.sent < info.limit) {
2694 				ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info);
2695 				if (ret <= 0)
2696 					break;
2697 
2698 				MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_RETRANSSEGS);
2699 				copied += ret;
2700 				info.sent += ret;
2701 			}
2702 			if (copied) {
2703 				len = max(copied, len);
2704 				tcp_push(ssk, 0, info.mss_now, tcp_sk(ssk)->nonagle,
2705 					 info.size_goal);
2706 				WRITE_ONCE(msk->allow_infinite_fallback, false);
2707 			}
2708 
2709 			release_sock(ssk);
2710 		}
2711 	}
2712 
2713 	msk->bytes_retrans += len;
2714 	dfrag->already_sent = max(dfrag->already_sent, len);
2715 
2716 reset_timer:
2717 	mptcp_check_and_set_pending(sk);
2718 
2719 	if (!mptcp_rtx_timer_pending(sk))
2720 		mptcp_reset_rtx_timer(sk);
2721 }
2722 
2723 /* schedule the timeout timer for the relevant event: either close timeout
2724  * or mp_fail timeout. The close timeout takes precedence on the mp_fail one
2725  */
mptcp_reset_tout_timer(struct mptcp_sock * msk,unsigned long fail_tout)2726 void mptcp_reset_tout_timer(struct mptcp_sock *msk, unsigned long fail_tout)
2727 {
2728 	struct sock *sk = (struct sock *)msk;
2729 	unsigned long timeout, close_timeout;
2730 
2731 	if (!fail_tout && !inet_csk(sk)->icsk_mtup.probe_timestamp)
2732 		return;
2733 
2734 	close_timeout = (unsigned long)inet_csk(sk)->icsk_mtup.probe_timestamp -
2735 			tcp_jiffies32 + jiffies + mptcp_close_timeout(sk);
2736 
2737 	/* the close timeout takes precedence on the fail one, and here at least one of
2738 	 * them is active
2739 	 */
2740 	timeout = inet_csk(sk)->icsk_mtup.probe_timestamp ? close_timeout : fail_tout;
2741 
2742 	sk_reset_timer(sk, &sk->sk_timer, timeout);
2743 }
2744 
mptcp_mp_fail_no_response(struct mptcp_sock * msk)2745 static void mptcp_mp_fail_no_response(struct mptcp_sock *msk)
2746 {
2747 	struct sock *ssk = msk->first;
2748 	bool slow;
2749 
2750 	if (!ssk)
2751 		return;
2752 
2753 	pr_debug("MP_FAIL doesn't respond, reset the subflow\n");
2754 
2755 	slow = lock_sock_fast(ssk);
2756 	mptcp_subflow_reset(ssk);
2757 	WRITE_ONCE(mptcp_subflow_ctx(ssk)->fail_tout, 0);
2758 	unlock_sock_fast(ssk, slow);
2759 }
2760 
mptcp_do_fastclose(struct sock * sk)2761 static void mptcp_do_fastclose(struct sock *sk)
2762 {
2763 	struct mptcp_subflow_context *subflow, *tmp;
2764 	struct mptcp_sock *msk = mptcp_sk(sk);
2765 
2766 	mptcp_set_state(sk, TCP_CLOSE);
2767 	mptcp_for_each_subflow_safe(msk, subflow, tmp)
2768 		__mptcp_close_ssk(sk, mptcp_subflow_tcp_sock(subflow),
2769 				  subflow, MPTCP_CF_FASTCLOSE);
2770 }
2771 
mptcp_worker(struct work_struct * work)2772 static void mptcp_worker(struct work_struct *work)
2773 {
2774 	struct mptcp_sock *msk = container_of(work, struct mptcp_sock, work);
2775 	struct sock *sk = (struct sock *)msk;
2776 	unsigned long fail_tout;
2777 	int state;
2778 
2779 	lock_sock(sk);
2780 	state = sk->sk_state;
2781 	if (unlikely((1 << state) & (TCPF_CLOSE | TCPF_LISTEN)))
2782 		goto unlock;
2783 
2784 	mptcp_check_fastclose(msk);
2785 
2786 	mptcp_pm_nl_work(msk);
2787 
2788 	mptcp_check_send_data_fin(sk);
2789 	mptcp_check_data_fin_ack(sk);
2790 	mptcp_check_data_fin(sk);
2791 
2792 	if (test_and_clear_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))
2793 		__mptcp_close_subflow(sk);
2794 
2795 	if (mptcp_close_tout_expired(sk)) {
2796 		mptcp_do_fastclose(sk);
2797 		mptcp_close_wake_up(sk);
2798 	}
2799 
2800 	if (sock_flag(sk, SOCK_DEAD) && sk->sk_state == TCP_CLOSE) {
2801 		__mptcp_destroy_sock(sk);
2802 		goto unlock;
2803 	}
2804 
2805 	if (test_and_clear_bit(MPTCP_WORK_RTX, &msk->flags))
2806 		__mptcp_retrans(sk);
2807 
2808 	fail_tout = msk->first ? READ_ONCE(mptcp_subflow_ctx(msk->first)->fail_tout) : 0;
2809 	if (fail_tout && time_after(jiffies, fail_tout))
2810 		mptcp_mp_fail_no_response(msk);
2811 
2812 unlock:
2813 	release_sock(sk);
2814 	sock_put(sk);
2815 }
2816 
__mptcp_init_sock(struct sock * sk)2817 static void __mptcp_init_sock(struct sock *sk)
2818 {
2819 	struct mptcp_sock *msk = mptcp_sk(sk);
2820 
2821 	INIT_LIST_HEAD(&msk->conn_list);
2822 	INIT_LIST_HEAD(&msk->join_list);
2823 	INIT_LIST_HEAD(&msk->rtx_queue);
2824 	INIT_WORK(&msk->work, mptcp_worker);
2825 	__skb_queue_head_init(&msk->receive_queue);
2826 	msk->out_of_order_queue = RB_ROOT;
2827 	msk->first_pending = NULL;
2828 	WRITE_ONCE(msk->rmem_fwd_alloc, 0);
2829 	WRITE_ONCE(msk->rmem_released, 0);
2830 	msk->timer_ival = TCP_RTO_MIN;
2831 	msk->scaling_ratio = TCP_DEFAULT_SCALING_RATIO;
2832 
2833 	WRITE_ONCE(msk->first, NULL);
2834 	inet_csk(sk)->icsk_sync_mss = mptcp_sync_mss;
2835 	WRITE_ONCE(msk->csum_enabled, mptcp_is_checksum_enabled(sock_net(sk)));
2836 	WRITE_ONCE(msk->allow_infinite_fallback, true);
2837 	msk->recovery = false;
2838 	msk->subflow_id = 1;
2839 	msk->last_data_sent = tcp_jiffies32;
2840 	msk->last_data_recv = tcp_jiffies32;
2841 	msk->last_ack_recv = tcp_jiffies32;
2842 
2843 	mptcp_pm_data_init(msk);
2844 
2845 	/* re-use the csk retrans timer for MPTCP-level retrans */
2846 	timer_setup(&msk->sk.icsk_retransmit_timer, mptcp_retransmit_timer, 0);
2847 	timer_setup(&sk->sk_timer, mptcp_tout_timer, 0);
2848 }
2849 
mptcp_ca_reset(struct sock * sk)2850 static void mptcp_ca_reset(struct sock *sk)
2851 {
2852 	struct inet_connection_sock *icsk = inet_csk(sk);
2853 
2854 	tcp_assign_congestion_control(sk);
2855 	strscpy(mptcp_sk(sk)->ca_name, icsk->icsk_ca_ops->name,
2856 		sizeof(mptcp_sk(sk)->ca_name));
2857 
2858 	/* no need to keep a reference to the ops, the name will suffice */
2859 	tcp_cleanup_congestion_control(sk);
2860 	icsk->icsk_ca_ops = NULL;
2861 }
2862 
mptcp_init_sock(struct sock * sk)2863 static int mptcp_init_sock(struct sock *sk)
2864 {
2865 	struct net *net = sock_net(sk);
2866 	int ret;
2867 
2868 	__mptcp_init_sock(sk);
2869 
2870 	if (!mptcp_is_enabled(net))
2871 		return -ENOPROTOOPT;
2872 
2873 	if (unlikely(!net->mib.mptcp_statistics) && !mptcp_mib_alloc(net))
2874 		return -ENOMEM;
2875 
2876 	rcu_read_lock();
2877 	ret = mptcp_init_sched(mptcp_sk(sk),
2878 			       mptcp_sched_find(mptcp_get_scheduler(net)));
2879 	rcu_read_unlock();
2880 	if (ret)
2881 		return ret;
2882 
2883 	set_bit(SOCK_CUSTOM_SOCKOPT, &sk->sk_socket->flags);
2884 
2885 	/* fetch the ca name; do it outside __mptcp_init_sock(), so that clone will
2886 	 * propagate the correct value
2887 	 */
2888 	mptcp_ca_reset(sk);
2889 
2890 	sk_sockets_allocated_inc(sk);
2891 	sk->sk_rcvbuf = READ_ONCE(net->ipv4.sysctl_tcp_rmem[1]);
2892 	sk->sk_sndbuf = READ_ONCE(net->ipv4.sysctl_tcp_wmem[1]);
2893 
2894 	return 0;
2895 }
2896 
__mptcp_clear_xmit(struct sock * sk)2897 static void __mptcp_clear_xmit(struct sock *sk)
2898 {
2899 	struct mptcp_sock *msk = mptcp_sk(sk);
2900 	struct mptcp_data_frag *dtmp, *dfrag;
2901 
2902 	WRITE_ONCE(msk->first_pending, NULL);
2903 	list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list)
2904 		dfrag_clear(sk, dfrag);
2905 }
2906 
mptcp_cancel_work(struct sock * sk)2907 void mptcp_cancel_work(struct sock *sk)
2908 {
2909 	struct mptcp_sock *msk = mptcp_sk(sk);
2910 
2911 	if (cancel_work_sync(&msk->work))
2912 		__sock_put(sk);
2913 }
2914 
mptcp_subflow_shutdown(struct sock * sk,struct sock * ssk,int how)2915 void mptcp_subflow_shutdown(struct sock *sk, struct sock *ssk, int how)
2916 {
2917 	lock_sock(ssk);
2918 
2919 	switch (ssk->sk_state) {
2920 	case TCP_LISTEN:
2921 		if (!(how & RCV_SHUTDOWN))
2922 			break;
2923 		fallthrough;
2924 	case TCP_SYN_SENT:
2925 		WARN_ON_ONCE(tcp_disconnect(ssk, O_NONBLOCK));
2926 		break;
2927 	default:
2928 		if (__mptcp_check_fallback(mptcp_sk(sk))) {
2929 			pr_debug("Fallback\n");
2930 			ssk->sk_shutdown |= how;
2931 			tcp_shutdown(ssk, how);
2932 
2933 			/* simulate the data_fin ack reception to let the state
2934 			 * machine move forward
2935 			 */
2936 			WRITE_ONCE(mptcp_sk(sk)->snd_una, mptcp_sk(sk)->snd_nxt);
2937 			mptcp_schedule_work(sk);
2938 		} else {
2939 			pr_debug("Sending DATA_FIN on subflow %p\n", ssk);
2940 			tcp_send_ack(ssk);
2941 			if (!mptcp_rtx_timer_pending(sk))
2942 				mptcp_reset_rtx_timer(sk);
2943 		}
2944 		break;
2945 	}
2946 
2947 	release_sock(ssk);
2948 }
2949 
mptcp_set_state(struct sock * sk,int state)2950 void mptcp_set_state(struct sock *sk, int state)
2951 {
2952 	int oldstate = sk->sk_state;
2953 
2954 	switch (state) {
2955 	case TCP_ESTABLISHED:
2956 		if (oldstate != TCP_ESTABLISHED)
2957 			MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_CURRESTAB);
2958 		break;
2959 	case TCP_CLOSE_WAIT:
2960 		/* Unlike TCP, MPTCP sk would not have the TCP_SYN_RECV state:
2961 		 * MPTCP "accepted" sockets will be created later on. So no
2962 		 * transition from TCP_SYN_RECV to TCP_CLOSE_WAIT.
2963 		 */
2964 		break;
2965 	default:
2966 		if (oldstate == TCP_ESTABLISHED || oldstate == TCP_CLOSE_WAIT)
2967 			MPTCP_DEC_STATS(sock_net(sk), MPTCP_MIB_CURRESTAB);
2968 	}
2969 
2970 	inet_sk_state_store(sk, state);
2971 }
2972 
2973 static const unsigned char new_state[16] = {
2974 	/* current state:     new state:      action:	*/
2975 	[0 /* (Invalid) */] = TCP_CLOSE,
2976 	[TCP_ESTABLISHED]   = TCP_FIN_WAIT1 | TCP_ACTION_FIN,
2977 	[TCP_SYN_SENT]      = TCP_CLOSE,
2978 	[TCP_SYN_RECV]      = TCP_FIN_WAIT1 | TCP_ACTION_FIN,
2979 	[TCP_FIN_WAIT1]     = TCP_FIN_WAIT1,
2980 	[TCP_FIN_WAIT2]     = TCP_FIN_WAIT2,
2981 	[TCP_TIME_WAIT]     = TCP_CLOSE,	/* should not happen ! */
2982 	[TCP_CLOSE]         = TCP_CLOSE,
2983 	[TCP_CLOSE_WAIT]    = TCP_LAST_ACK  | TCP_ACTION_FIN,
2984 	[TCP_LAST_ACK]      = TCP_LAST_ACK,
2985 	[TCP_LISTEN]        = TCP_CLOSE,
2986 	[TCP_CLOSING]       = TCP_CLOSING,
2987 	[TCP_NEW_SYN_RECV]  = TCP_CLOSE,	/* should not happen ! */
2988 };
2989 
mptcp_close_state(struct sock * sk)2990 static int mptcp_close_state(struct sock *sk)
2991 {
2992 	int next = (int)new_state[sk->sk_state];
2993 	int ns = next & TCP_STATE_MASK;
2994 
2995 	mptcp_set_state(sk, ns);
2996 
2997 	return next & TCP_ACTION_FIN;
2998 }
2999 
mptcp_check_send_data_fin(struct sock * sk)3000 static void mptcp_check_send_data_fin(struct sock *sk)
3001 {
3002 	struct mptcp_subflow_context *subflow;
3003 	struct mptcp_sock *msk = mptcp_sk(sk);
3004 
3005 	pr_debug("msk=%p snd_data_fin_enable=%d pending=%d snd_nxt=%llu write_seq=%llu\n",
3006 		 msk, msk->snd_data_fin_enable, !!mptcp_send_head(sk),
3007 		 msk->snd_nxt, msk->write_seq);
3008 
3009 	/* we still need to enqueue subflows or not really shutting down,
3010 	 * skip this
3011 	 */
3012 	if (!msk->snd_data_fin_enable || msk->snd_nxt + 1 != msk->write_seq ||
3013 	    mptcp_send_head(sk))
3014 		return;
3015 
3016 	WRITE_ONCE(msk->snd_nxt, msk->write_seq);
3017 
3018 	mptcp_for_each_subflow(msk, subflow) {
3019 		struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow);
3020 
3021 		mptcp_subflow_shutdown(sk, tcp_sk, SEND_SHUTDOWN);
3022 	}
3023 }
3024 
__mptcp_wr_shutdown(struct sock * sk)3025 static void __mptcp_wr_shutdown(struct sock *sk)
3026 {
3027 	struct mptcp_sock *msk = mptcp_sk(sk);
3028 
3029 	pr_debug("msk=%p snd_data_fin_enable=%d shutdown=%x state=%d pending=%d\n",
3030 		 msk, msk->snd_data_fin_enable, sk->sk_shutdown, sk->sk_state,
3031 		 !!mptcp_send_head(sk));
3032 
3033 	/* will be ignored by fallback sockets */
3034 	WRITE_ONCE(msk->write_seq, msk->write_seq + 1);
3035 	WRITE_ONCE(msk->snd_data_fin_enable, 1);
3036 
3037 	mptcp_check_send_data_fin(sk);
3038 }
3039 
__mptcp_destroy_sock(struct sock * sk)3040 static void __mptcp_destroy_sock(struct sock *sk)
3041 {
3042 	struct mptcp_sock *msk = mptcp_sk(sk);
3043 
3044 	pr_debug("msk=%p\n", msk);
3045 
3046 	might_sleep();
3047 
3048 	mptcp_stop_rtx_timer(sk);
3049 	sk_stop_timer(sk, &sk->sk_timer);
3050 	msk->pm.status = 0;
3051 	mptcp_release_sched(msk);
3052 
3053 	sk->sk_prot->destroy(sk);
3054 
3055 	WARN_ON_ONCE(READ_ONCE(msk->rmem_fwd_alloc));
3056 	WARN_ON_ONCE(msk->rmem_released);
3057 	sk_stream_kill_queues(sk);
3058 	xfrm_sk_free_policy(sk);
3059 
3060 	sock_put(sk);
3061 }
3062 
__mptcp_unaccepted_force_close(struct sock * sk)3063 void __mptcp_unaccepted_force_close(struct sock *sk)
3064 {
3065 	sock_set_flag(sk, SOCK_DEAD);
3066 	mptcp_do_fastclose(sk);
3067 	__mptcp_destroy_sock(sk);
3068 }
3069 
mptcp_check_readable(struct sock * sk)3070 static __poll_t mptcp_check_readable(struct sock *sk)
3071 {
3072 	return mptcp_epollin_ready(sk) ? EPOLLIN | EPOLLRDNORM : 0;
3073 }
3074 
mptcp_check_listen_stop(struct sock * sk)3075 static void mptcp_check_listen_stop(struct sock *sk)
3076 {
3077 	struct sock *ssk;
3078 
3079 	if (inet_sk_state_load(sk) != TCP_LISTEN)
3080 		return;
3081 
3082 	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
3083 	ssk = mptcp_sk(sk)->first;
3084 	if (WARN_ON_ONCE(!ssk || inet_sk_state_load(ssk) != TCP_LISTEN))
3085 		return;
3086 
3087 	lock_sock_nested(ssk, SINGLE_DEPTH_NESTING);
3088 	tcp_set_state(ssk, TCP_CLOSE);
3089 	mptcp_subflow_queue_clean(sk, ssk);
3090 	inet_csk_listen_stop(ssk);
3091 	mptcp_event_pm_listener(ssk, MPTCP_EVENT_LISTENER_CLOSED);
3092 	release_sock(ssk);
3093 }
3094 
__mptcp_close(struct sock * sk,long timeout)3095 bool __mptcp_close(struct sock *sk, long timeout)
3096 {
3097 	struct mptcp_subflow_context *subflow;
3098 	struct mptcp_sock *msk = mptcp_sk(sk);
3099 	bool do_cancel_work = false;
3100 	int subflows_alive = 0;
3101 
3102 	WRITE_ONCE(sk->sk_shutdown, SHUTDOWN_MASK);
3103 
3104 	if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE)) {
3105 		mptcp_check_listen_stop(sk);
3106 		mptcp_set_state(sk, TCP_CLOSE);
3107 		goto cleanup;
3108 	}
3109 
3110 	if (mptcp_data_avail(msk) || timeout < 0) {
3111 		/* If the msk has read data, or the caller explicitly ask it,
3112 		 * do the MPTCP equivalent of TCP reset, aka MPTCP fastclose
3113 		 */
3114 		mptcp_do_fastclose(sk);
3115 		timeout = 0;
3116 	} else if (mptcp_close_state(sk)) {
3117 		__mptcp_wr_shutdown(sk);
3118 	}
3119 
3120 	sk_stream_wait_close(sk, timeout);
3121 
3122 cleanup:
3123 	/* orphan all the subflows */
3124 	mptcp_for_each_subflow(msk, subflow) {
3125 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
3126 		bool slow = lock_sock_fast_nested(ssk);
3127 
3128 		subflows_alive += ssk->sk_state != TCP_CLOSE;
3129 
3130 		/* since the close timeout takes precedence on the fail one,
3131 		 * cancel the latter
3132 		 */
3133 		if (ssk == msk->first)
3134 			subflow->fail_tout = 0;
3135 
3136 		/* detach from the parent socket, but allow data_ready to
3137 		 * push incoming data into the mptcp stack, to properly ack it
3138 		 */
3139 		ssk->sk_socket = NULL;
3140 		ssk->sk_wq = NULL;
3141 		unlock_sock_fast(ssk, slow);
3142 	}
3143 	sock_orphan(sk);
3144 
3145 	/* all the subflows are closed, only timeout can change the msk
3146 	 * state, let's not keep resources busy for no reasons
3147 	 */
3148 	if (subflows_alive == 0)
3149 		mptcp_set_state(sk, TCP_CLOSE);
3150 
3151 	sock_hold(sk);
3152 	pr_debug("msk=%p state=%d\n", sk, sk->sk_state);
3153 	mptcp_pm_connection_closed(msk);
3154 
3155 	if (sk->sk_state == TCP_CLOSE) {
3156 		__mptcp_destroy_sock(sk);
3157 		do_cancel_work = true;
3158 	} else {
3159 		mptcp_start_tout_timer(sk);
3160 	}
3161 
3162 	return do_cancel_work;
3163 }
3164 
mptcp_close(struct sock * sk,long timeout)3165 static void mptcp_close(struct sock *sk, long timeout)
3166 {
3167 	bool do_cancel_work;
3168 
3169 	lock_sock(sk);
3170 
3171 	do_cancel_work = __mptcp_close(sk, timeout);
3172 	release_sock(sk);
3173 	if (do_cancel_work)
3174 		mptcp_cancel_work(sk);
3175 
3176 	sock_put(sk);
3177 }
3178 
mptcp_copy_inaddrs(struct sock * msk,const struct sock * ssk)3179 static void mptcp_copy_inaddrs(struct sock *msk, const struct sock *ssk)
3180 {
3181 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
3182 	const struct ipv6_pinfo *ssk6 = inet6_sk(ssk);
3183 	struct ipv6_pinfo *msk6 = inet6_sk(msk);
3184 
3185 	msk->sk_v6_daddr = ssk->sk_v6_daddr;
3186 	msk->sk_v6_rcv_saddr = ssk->sk_v6_rcv_saddr;
3187 
3188 	if (msk6 && ssk6) {
3189 		msk6->saddr = ssk6->saddr;
3190 		msk6->flow_label = ssk6->flow_label;
3191 	}
3192 #endif
3193 
3194 	inet_sk(msk)->inet_num = inet_sk(ssk)->inet_num;
3195 	inet_sk(msk)->inet_dport = inet_sk(ssk)->inet_dport;
3196 	inet_sk(msk)->inet_sport = inet_sk(ssk)->inet_sport;
3197 	inet_sk(msk)->inet_daddr = inet_sk(ssk)->inet_daddr;
3198 	inet_sk(msk)->inet_saddr = inet_sk(ssk)->inet_saddr;
3199 	inet_sk(msk)->inet_rcv_saddr = inet_sk(ssk)->inet_rcv_saddr;
3200 }
3201 
mptcp_disconnect(struct sock * sk,int flags)3202 static int mptcp_disconnect(struct sock *sk, int flags)
3203 {
3204 	struct mptcp_sock *msk = mptcp_sk(sk);
3205 
3206 	/* We are on the fastopen error path. We can't call straight into the
3207 	 * subflows cleanup code due to lock nesting (we are already under
3208 	 * msk->firstsocket lock).
3209 	 */
3210 	if (msk->fastopening)
3211 		return -EBUSY;
3212 
3213 	mptcp_check_listen_stop(sk);
3214 	mptcp_set_state(sk, TCP_CLOSE);
3215 
3216 	mptcp_stop_rtx_timer(sk);
3217 	mptcp_stop_tout_timer(sk);
3218 
3219 	mptcp_pm_connection_closed(msk);
3220 
3221 	/* msk->subflow is still intact, the following will not free the first
3222 	 * subflow
3223 	 */
3224 	mptcp_destroy_common(msk, MPTCP_CF_FASTCLOSE);
3225 	WRITE_ONCE(msk->flags, 0);
3226 	msk->cb_flags = 0;
3227 	msk->recovery = false;
3228 	WRITE_ONCE(msk->can_ack, false);
3229 	WRITE_ONCE(msk->fully_established, false);
3230 	WRITE_ONCE(msk->rcv_data_fin, false);
3231 	WRITE_ONCE(msk->snd_data_fin_enable, false);
3232 	WRITE_ONCE(msk->rcv_fastclose, false);
3233 	WRITE_ONCE(msk->use_64bit_ack, false);
3234 	WRITE_ONCE(msk->csum_enabled, mptcp_is_checksum_enabled(sock_net(sk)));
3235 	mptcp_pm_data_reset(msk);
3236 	mptcp_ca_reset(sk);
3237 	msk->bytes_consumed = 0;
3238 	msk->bytes_acked = 0;
3239 	msk->bytes_received = 0;
3240 	msk->bytes_sent = 0;
3241 	msk->bytes_retrans = 0;
3242 	msk->rcvspace_init = 0;
3243 
3244 	WRITE_ONCE(sk->sk_shutdown, 0);
3245 	sk_error_report(sk);
3246 	return 0;
3247 }
3248 
3249 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
mptcp_inet6_sk(const struct sock * sk)3250 static struct ipv6_pinfo *mptcp_inet6_sk(const struct sock *sk)
3251 {
3252 	unsigned int offset = sizeof(struct mptcp6_sock) - sizeof(struct ipv6_pinfo);
3253 
3254 	return (struct ipv6_pinfo *)(((u8 *)sk) + offset);
3255 }
3256 
mptcp_copy_ip6_options(struct sock * newsk,const struct sock * sk)3257 static void mptcp_copy_ip6_options(struct sock *newsk, const struct sock *sk)
3258 {
3259 	const struct ipv6_pinfo *np = inet6_sk(sk);
3260 	struct ipv6_txoptions *opt;
3261 	struct ipv6_pinfo *newnp;
3262 
3263 	newnp = inet6_sk(newsk);
3264 
3265 	rcu_read_lock();
3266 	opt = rcu_dereference(np->opt);
3267 	if (opt) {
3268 		opt = ipv6_dup_options(newsk, opt);
3269 		if (!opt)
3270 			net_warn_ratelimited("%s: Failed to copy ip6 options\n", __func__);
3271 	}
3272 	RCU_INIT_POINTER(newnp->opt, opt);
3273 	rcu_read_unlock();
3274 }
3275 #endif
3276 
mptcp_copy_ip_options(struct sock * newsk,const struct sock * sk)3277 static void mptcp_copy_ip_options(struct sock *newsk, const struct sock *sk)
3278 {
3279 	struct ip_options_rcu *inet_opt, *newopt = NULL;
3280 	const struct inet_sock *inet = inet_sk(sk);
3281 	struct inet_sock *newinet;
3282 
3283 	newinet = inet_sk(newsk);
3284 
3285 	rcu_read_lock();
3286 	inet_opt = rcu_dereference(inet->inet_opt);
3287 	if (inet_opt) {
3288 		newopt = sock_kmalloc(newsk, sizeof(*inet_opt) +
3289 				      inet_opt->opt.optlen, GFP_ATOMIC);
3290 		if (newopt)
3291 			memcpy(newopt, inet_opt, sizeof(*inet_opt) +
3292 			       inet_opt->opt.optlen);
3293 		else
3294 			net_warn_ratelimited("%s: Failed to copy ip options\n", __func__);
3295 	}
3296 	RCU_INIT_POINTER(newinet->inet_opt, newopt);
3297 	rcu_read_unlock();
3298 }
3299 
mptcp_sk_clone_init(const struct sock * sk,const struct mptcp_options_received * mp_opt,struct sock * ssk,struct request_sock * req)3300 struct sock *mptcp_sk_clone_init(const struct sock *sk,
3301 				 const struct mptcp_options_received *mp_opt,
3302 				 struct sock *ssk,
3303 				 struct request_sock *req)
3304 {
3305 	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
3306 	struct sock *nsk = sk_clone_lock(sk, GFP_ATOMIC);
3307 	struct mptcp_subflow_context *subflow;
3308 	struct mptcp_sock *msk;
3309 
3310 	if (!nsk)
3311 		return NULL;
3312 
3313 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
3314 	if (nsk->sk_family == AF_INET6)
3315 		inet_sk(nsk)->pinet6 = mptcp_inet6_sk(nsk);
3316 #endif
3317 
3318 	__mptcp_init_sock(nsk);
3319 
3320 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
3321 	if (nsk->sk_family == AF_INET6)
3322 		mptcp_copy_ip6_options(nsk, sk);
3323 	else
3324 #endif
3325 		mptcp_copy_ip_options(nsk, sk);
3326 
3327 	msk = mptcp_sk(nsk);
3328 	WRITE_ONCE(msk->local_key, subflow_req->local_key);
3329 	WRITE_ONCE(msk->token, subflow_req->token);
3330 	msk->in_accept_queue = 1;
3331 	WRITE_ONCE(msk->fully_established, false);
3332 	if (mp_opt->suboptions & OPTION_MPTCP_CSUMREQD)
3333 		WRITE_ONCE(msk->csum_enabled, true);
3334 
3335 	WRITE_ONCE(msk->write_seq, subflow_req->idsn + 1);
3336 	WRITE_ONCE(msk->snd_nxt, msk->write_seq);
3337 	WRITE_ONCE(msk->snd_una, msk->write_seq);
3338 	WRITE_ONCE(msk->wnd_end, msk->snd_nxt + tcp_sk(ssk)->snd_wnd);
3339 	msk->setsockopt_seq = mptcp_sk(sk)->setsockopt_seq;
3340 	mptcp_init_sched(msk, mptcp_sk(sk)->sched);
3341 
3342 	/* passive msk is created after the first/MPC subflow */
3343 	msk->subflow_id = 2;
3344 
3345 	sock_reset_flag(nsk, SOCK_RCU_FREE);
3346 	security_inet_csk_clone(nsk, req);
3347 
3348 	/* this can't race with mptcp_close(), as the msk is
3349 	 * not yet exposted to user-space
3350 	 */
3351 	mptcp_set_state(nsk, TCP_ESTABLISHED);
3352 
3353 	/* The msk maintain a ref to each subflow in the connections list */
3354 	WRITE_ONCE(msk->first, ssk);
3355 	subflow = mptcp_subflow_ctx(ssk);
3356 	list_add(&subflow->node, &msk->conn_list);
3357 	sock_hold(ssk);
3358 
3359 	/* new mpc subflow takes ownership of the newly
3360 	 * created mptcp socket
3361 	 */
3362 	mptcp_token_accept(subflow_req, msk);
3363 
3364 	/* set msk addresses early to ensure mptcp_pm_get_local_id()
3365 	 * uses the correct data
3366 	 */
3367 	mptcp_copy_inaddrs(nsk, ssk);
3368 	__mptcp_propagate_sndbuf(nsk, ssk);
3369 
3370 	mptcp_rcv_space_init(msk, ssk);
3371 
3372 	if (mp_opt->suboptions & OPTION_MPTCP_MPC_ACK)
3373 		__mptcp_subflow_fully_established(msk, subflow, mp_opt);
3374 	bh_unlock_sock(nsk);
3375 
3376 	/* note: the newly allocated socket refcount is 2 now */
3377 	return nsk;
3378 }
3379 
mptcp_rcv_space_init(struct mptcp_sock * msk,const struct sock * ssk)3380 void mptcp_rcv_space_init(struct mptcp_sock *msk, const struct sock *ssk)
3381 {
3382 	const struct tcp_sock *tp = tcp_sk(ssk);
3383 
3384 	msk->rcvspace_init = 1;
3385 	msk->rcvq_space.copied = 0;
3386 	msk->rcvq_space.rtt_us = 0;
3387 
3388 	msk->rcvq_space.time = tp->tcp_mstamp;
3389 
3390 	/* initial rcv_space offering made to peer */
3391 	msk->rcvq_space.space = min_t(u32, tp->rcv_wnd,
3392 				      TCP_INIT_CWND * tp->advmss);
3393 	if (msk->rcvq_space.space == 0)
3394 		msk->rcvq_space.space = TCP_INIT_CWND * TCP_MSS_DEFAULT;
3395 }
3396 
mptcp_destroy_common(struct mptcp_sock * msk,unsigned int flags)3397 void mptcp_destroy_common(struct mptcp_sock *msk, unsigned int flags)
3398 {
3399 	struct mptcp_subflow_context *subflow, *tmp;
3400 	struct sock *sk = (struct sock *)msk;
3401 
3402 	__mptcp_clear_xmit(sk);
3403 
3404 	/* join list will be eventually flushed (with rst) at sock lock release time */
3405 	mptcp_for_each_subflow_safe(msk, subflow, tmp)
3406 		__mptcp_close_ssk(sk, mptcp_subflow_tcp_sock(subflow), subflow, flags);
3407 
3408 	/* move to sk_receive_queue, sk_stream_kill_queues will purge it */
3409 	mptcp_data_lock(sk);
3410 	skb_queue_splice_tail_init(&msk->receive_queue, &sk->sk_receive_queue);
3411 	__skb_queue_purge(&sk->sk_receive_queue);
3412 	skb_rbtree_purge(&msk->out_of_order_queue);
3413 	mptcp_data_unlock(sk);
3414 
3415 	/* move all the rx fwd alloc into the sk_mem_reclaim_final in
3416 	 * inet_sock_destruct() will dispose it
3417 	 */
3418 	sk_forward_alloc_add(sk, msk->rmem_fwd_alloc);
3419 	WRITE_ONCE(msk->rmem_fwd_alloc, 0);
3420 	mptcp_token_destroy(msk);
3421 	mptcp_pm_free_anno_list(msk);
3422 	mptcp_free_local_addr_list(msk);
3423 }
3424 
mptcp_destroy(struct sock * sk)3425 static void mptcp_destroy(struct sock *sk)
3426 {
3427 	struct mptcp_sock *msk = mptcp_sk(sk);
3428 
3429 	/* allow the following to close even the initial subflow */
3430 	msk->free_first = 1;
3431 	mptcp_destroy_common(msk, 0);
3432 	sk_sockets_allocated_dec(sk);
3433 }
3434 
__mptcp_data_acked(struct sock * sk)3435 void __mptcp_data_acked(struct sock *sk)
3436 {
3437 	if (!sock_owned_by_user(sk))
3438 		__mptcp_clean_una(sk);
3439 	else
3440 		__set_bit(MPTCP_CLEAN_UNA, &mptcp_sk(sk)->cb_flags);
3441 }
3442 
__mptcp_check_push(struct sock * sk,struct sock * ssk)3443 void __mptcp_check_push(struct sock *sk, struct sock *ssk)
3444 {
3445 	if (!mptcp_send_head(sk))
3446 		return;
3447 
3448 	if (!sock_owned_by_user(sk))
3449 		__mptcp_subflow_push_pending(sk, ssk, false);
3450 	else
3451 		__set_bit(MPTCP_PUSH_PENDING, &mptcp_sk(sk)->cb_flags);
3452 }
3453 
3454 #define MPTCP_FLAGS_PROCESS_CTX_NEED (BIT(MPTCP_PUSH_PENDING) | \
3455 				      BIT(MPTCP_RETRANSMIT) | \
3456 				      BIT(MPTCP_FLUSH_JOIN_LIST))
3457 
3458 /* processes deferred events and flush wmem */
mptcp_release_cb(struct sock * sk)3459 static void mptcp_release_cb(struct sock *sk)
3460 	__must_hold(&sk->sk_lock.slock)
3461 {
3462 	struct mptcp_sock *msk = mptcp_sk(sk);
3463 
3464 	for (;;) {
3465 		unsigned long flags = (msk->cb_flags & MPTCP_FLAGS_PROCESS_CTX_NEED);
3466 		struct list_head join_list;
3467 
3468 		if (!flags)
3469 			break;
3470 
3471 		INIT_LIST_HEAD(&join_list);
3472 		list_splice_init(&msk->join_list, &join_list);
3473 
3474 		/* the following actions acquire the subflow socket lock
3475 		 *
3476 		 * 1) can't be invoked in atomic scope
3477 		 * 2) must avoid ABBA deadlock with msk socket spinlock: the RX
3478 		 *    datapath acquires the msk socket spinlock while helding
3479 		 *    the subflow socket lock
3480 		 */
3481 		msk->cb_flags &= ~flags;
3482 		spin_unlock_bh(&sk->sk_lock.slock);
3483 
3484 		if (flags & BIT(MPTCP_FLUSH_JOIN_LIST))
3485 			__mptcp_flush_join_list(sk, &join_list);
3486 		if (flags & BIT(MPTCP_PUSH_PENDING))
3487 			__mptcp_push_pending(sk, 0);
3488 		if (flags & BIT(MPTCP_RETRANSMIT))
3489 			__mptcp_retrans(sk);
3490 
3491 		cond_resched();
3492 		spin_lock_bh(&sk->sk_lock.slock);
3493 	}
3494 
3495 	if (__test_and_clear_bit(MPTCP_CLEAN_UNA, &msk->cb_flags))
3496 		__mptcp_clean_una_wakeup(sk);
3497 	if (unlikely(msk->cb_flags)) {
3498 		/* be sure to sync the msk state before taking actions
3499 		 * depending on sk_state (MPTCP_ERROR_REPORT)
3500 		 * On sk release avoid actions depending on the first subflow
3501 		 */
3502 		if (__test_and_clear_bit(MPTCP_SYNC_STATE, &msk->cb_flags) && msk->first)
3503 			__mptcp_sync_state(sk, msk->pending_state);
3504 		if (__test_and_clear_bit(MPTCP_ERROR_REPORT, &msk->cb_flags))
3505 			__mptcp_error_report(sk);
3506 		if (__test_and_clear_bit(MPTCP_SYNC_SNDBUF, &msk->cb_flags))
3507 			__mptcp_sync_sndbuf(sk);
3508 	}
3509 
3510 	__mptcp_update_rmem(sk);
3511 }
3512 
3513 /* MP_JOIN client subflow must wait for 4th ack before sending any data:
3514  * TCP can't schedule delack timer before the subflow is fully established.
3515  * MPTCP uses the delack timer to do 3rd ack retransmissions
3516  */
schedule_3rdack_retransmission(struct sock * ssk)3517 static void schedule_3rdack_retransmission(struct sock *ssk)
3518 {
3519 	struct inet_connection_sock *icsk = inet_csk(ssk);
3520 	struct tcp_sock *tp = tcp_sk(ssk);
3521 	unsigned long timeout;
3522 
3523 	if (READ_ONCE(mptcp_subflow_ctx(ssk)->fully_established))
3524 		return;
3525 
3526 	/* reschedule with a timeout above RTT, as we must look only for drop */
3527 	if (tp->srtt_us)
3528 		timeout = usecs_to_jiffies(tp->srtt_us >> (3 - 1));
3529 	else
3530 		timeout = TCP_TIMEOUT_INIT;
3531 	timeout += jiffies;
3532 
3533 	WARN_ON_ONCE(icsk->icsk_ack.pending & ICSK_ACK_TIMER);
3534 	smp_store_release(&icsk->icsk_ack.pending,
3535 			  icsk->icsk_ack.pending | ICSK_ACK_SCHED | ICSK_ACK_TIMER);
3536 	icsk->icsk_ack.timeout = timeout;
3537 	sk_reset_timer(ssk, &icsk->icsk_delack_timer, timeout);
3538 }
3539 
mptcp_subflow_process_delegated(struct sock * ssk,long status)3540 void mptcp_subflow_process_delegated(struct sock *ssk, long status)
3541 {
3542 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
3543 	struct sock *sk = subflow->conn;
3544 
3545 	if (status & BIT(MPTCP_DELEGATE_SEND)) {
3546 		mptcp_data_lock(sk);
3547 		if (!sock_owned_by_user(sk))
3548 			__mptcp_subflow_push_pending(sk, ssk, true);
3549 		else
3550 			__set_bit(MPTCP_PUSH_PENDING, &mptcp_sk(sk)->cb_flags);
3551 		mptcp_data_unlock(sk);
3552 	}
3553 	if (status & BIT(MPTCP_DELEGATE_SNDBUF)) {
3554 		mptcp_data_lock(sk);
3555 		if (!sock_owned_by_user(sk))
3556 			__mptcp_sync_sndbuf(sk);
3557 		else
3558 			__set_bit(MPTCP_SYNC_SNDBUF, &mptcp_sk(sk)->cb_flags);
3559 		mptcp_data_unlock(sk);
3560 	}
3561 	if (status & BIT(MPTCP_DELEGATE_ACK))
3562 		schedule_3rdack_retransmission(ssk);
3563 }
3564 
mptcp_hash(struct sock * sk)3565 static int mptcp_hash(struct sock *sk)
3566 {
3567 	/* should never be called,
3568 	 * we hash the TCP subflows not the MPTCP socket
3569 	 */
3570 	WARN_ON_ONCE(1);
3571 	return 0;
3572 }
3573 
mptcp_unhash(struct sock * sk)3574 static void mptcp_unhash(struct sock *sk)
3575 {
3576 	/* called from sk_common_release(), but nothing to do here */
3577 }
3578 
mptcp_get_port(struct sock * sk,unsigned short snum)3579 static int mptcp_get_port(struct sock *sk, unsigned short snum)
3580 {
3581 	struct mptcp_sock *msk = mptcp_sk(sk);
3582 
3583 	pr_debug("msk=%p, ssk=%p\n", msk, msk->first);
3584 	if (WARN_ON_ONCE(!msk->first))
3585 		return -EINVAL;
3586 
3587 	return inet_csk_get_port(msk->first, snum);
3588 }
3589 
mptcp_finish_connect(struct sock * ssk)3590 void mptcp_finish_connect(struct sock *ssk)
3591 {
3592 	struct mptcp_subflow_context *subflow;
3593 	struct mptcp_sock *msk;
3594 	struct sock *sk;
3595 
3596 	subflow = mptcp_subflow_ctx(ssk);
3597 	sk = subflow->conn;
3598 	msk = mptcp_sk(sk);
3599 
3600 	pr_debug("msk=%p, token=%u\n", sk, subflow->token);
3601 
3602 	subflow->map_seq = subflow->iasn;
3603 	subflow->map_subflow_seq = 1;
3604 
3605 	/* the socket is not connected yet, no msk/subflow ops can access/race
3606 	 * accessing the field below
3607 	 */
3608 	WRITE_ONCE(msk->local_key, subflow->local_key);
3609 
3610 	mptcp_pm_new_connection(msk, ssk, 0);
3611 }
3612 
mptcp_sock_graft(struct sock * sk,struct socket * parent)3613 void mptcp_sock_graft(struct sock *sk, struct socket *parent)
3614 {
3615 	write_lock_bh(&sk->sk_callback_lock);
3616 	rcu_assign_pointer(sk->sk_wq, &parent->wq);
3617 	sk_set_socket(sk, parent);
3618 	sk->sk_uid = SOCK_INODE(parent)->i_uid;
3619 	write_unlock_bh(&sk->sk_callback_lock);
3620 }
3621 
mptcp_finish_join(struct sock * ssk)3622 bool mptcp_finish_join(struct sock *ssk)
3623 {
3624 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
3625 	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
3626 	struct sock *parent = (void *)msk;
3627 	bool ret = true;
3628 
3629 	pr_debug("msk=%p, subflow=%p\n", msk, subflow);
3630 
3631 	/* mptcp socket already closing? */
3632 	if (!mptcp_is_fully_established(parent)) {
3633 		subflow->reset_reason = MPTCP_RST_EMPTCP;
3634 		return false;
3635 	}
3636 
3637 	/* active subflow, already present inside the conn_list */
3638 	if (!list_empty(&subflow->node)) {
3639 		mptcp_subflow_joined(msk, ssk);
3640 		mptcp_propagate_sndbuf(parent, ssk);
3641 		return true;
3642 	}
3643 
3644 	if (!mptcp_pm_allow_new_subflow(msk))
3645 		goto err_prohibited;
3646 
3647 	/* If we can't acquire msk socket lock here, let the release callback
3648 	 * handle it
3649 	 */
3650 	mptcp_data_lock(parent);
3651 	if (!sock_owned_by_user(parent)) {
3652 		ret = __mptcp_finish_join(msk, ssk);
3653 		if (ret) {
3654 			sock_hold(ssk);
3655 			list_add_tail(&subflow->node, &msk->conn_list);
3656 		}
3657 	} else {
3658 		sock_hold(ssk);
3659 		list_add_tail(&subflow->node, &msk->join_list);
3660 		__set_bit(MPTCP_FLUSH_JOIN_LIST, &msk->cb_flags);
3661 	}
3662 	mptcp_data_unlock(parent);
3663 
3664 	if (!ret) {
3665 err_prohibited:
3666 		subflow->reset_reason = MPTCP_RST_EPROHIBIT;
3667 		return false;
3668 	}
3669 
3670 	return true;
3671 }
3672 
mptcp_shutdown(struct sock * sk,int how)3673 static void mptcp_shutdown(struct sock *sk, int how)
3674 {
3675 	pr_debug("sk=%p, how=%d\n", sk, how);
3676 
3677 	if ((how & SEND_SHUTDOWN) && mptcp_close_state(sk))
3678 		__mptcp_wr_shutdown(sk);
3679 }
3680 
mptcp_forward_alloc_get(const struct sock * sk)3681 static int mptcp_forward_alloc_get(const struct sock *sk)
3682 {
3683 	return READ_ONCE(sk->sk_forward_alloc) +
3684 	       READ_ONCE(mptcp_sk(sk)->rmem_fwd_alloc);
3685 }
3686 
mptcp_ioctl_outq(const struct mptcp_sock * msk,u64 v)3687 static int mptcp_ioctl_outq(const struct mptcp_sock *msk, u64 v)
3688 {
3689 	const struct sock *sk = (void *)msk;
3690 	u64 delta;
3691 
3692 	if (sk->sk_state == TCP_LISTEN)
3693 		return -EINVAL;
3694 
3695 	if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
3696 		return 0;
3697 
3698 	delta = msk->write_seq - v;
3699 	if (__mptcp_check_fallback(msk) && msk->first) {
3700 		struct tcp_sock *tp = tcp_sk(msk->first);
3701 
3702 		/* the first subflow is disconnected after close - see
3703 		 * __mptcp_close_ssk(). tcp_disconnect() moves the write_seq
3704 		 * so ignore that status, too.
3705 		 */
3706 		if (!((1 << msk->first->sk_state) &
3707 		      (TCPF_SYN_SENT | TCPF_SYN_RECV | TCPF_CLOSE)))
3708 			delta += READ_ONCE(tp->write_seq) - tp->snd_una;
3709 	}
3710 	if (delta > INT_MAX)
3711 		delta = INT_MAX;
3712 
3713 	return (int)delta;
3714 }
3715 
mptcp_ioctl(struct sock * sk,int cmd,int * karg)3716 static int mptcp_ioctl(struct sock *sk, int cmd, int *karg)
3717 {
3718 	struct mptcp_sock *msk = mptcp_sk(sk);
3719 	bool slow;
3720 
3721 	switch (cmd) {
3722 	case SIOCINQ:
3723 		if (sk->sk_state == TCP_LISTEN)
3724 			return -EINVAL;
3725 
3726 		lock_sock(sk);
3727 		__mptcp_move_skbs(msk);
3728 		*karg = mptcp_inq_hint(sk);
3729 		release_sock(sk);
3730 		break;
3731 	case SIOCOUTQ:
3732 		slow = lock_sock_fast(sk);
3733 		*karg = mptcp_ioctl_outq(msk, READ_ONCE(msk->snd_una));
3734 		unlock_sock_fast(sk, slow);
3735 		break;
3736 	case SIOCOUTQNSD:
3737 		slow = lock_sock_fast(sk);
3738 		*karg = mptcp_ioctl_outq(msk, msk->snd_nxt);
3739 		unlock_sock_fast(sk, slow);
3740 		break;
3741 	default:
3742 		return -ENOIOCTLCMD;
3743 	}
3744 
3745 	return 0;
3746 }
3747 
mptcp_connect(struct sock * sk,struct sockaddr * uaddr,int addr_len)3748 static int mptcp_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
3749 {
3750 	struct mptcp_subflow_context *subflow;
3751 	struct mptcp_sock *msk = mptcp_sk(sk);
3752 	int err = -EINVAL;
3753 	struct sock *ssk;
3754 
3755 	ssk = __mptcp_nmpc_sk(msk);
3756 	if (IS_ERR(ssk))
3757 		return PTR_ERR(ssk);
3758 
3759 	mptcp_set_state(sk, TCP_SYN_SENT);
3760 	subflow = mptcp_subflow_ctx(ssk);
3761 #ifdef CONFIG_TCP_MD5SIG
3762 	/* no MPTCP if MD5SIG is enabled on this socket or we may run out of
3763 	 * TCP option space.
3764 	 */
3765 	if (rcu_access_pointer(tcp_sk(ssk)->md5sig_info))
3766 		mptcp_subflow_early_fallback(msk, subflow);
3767 #endif
3768 	if (subflow->request_mptcp) {
3769 		if (mptcp_active_should_disable(sk)) {
3770 			MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPCAPABLEACTIVEDISABLED);
3771 			mptcp_subflow_early_fallback(msk, subflow);
3772 		} else if (mptcp_token_new_connect(ssk) < 0) {
3773 			MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_TOKENFALLBACKINIT);
3774 			mptcp_subflow_early_fallback(msk, subflow);
3775 		}
3776 	}
3777 
3778 	WRITE_ONCE(msk->write_seq, subflow->idsn);
3779 	WRITE_ONCE(msk->snd_nxt, subflow->idsn);
3780 	WRITE_ONCE(msk->snd_una, subflow->idsn);
3781 	if (likely(!__mptcp_check_fallback(msk)))
3782 		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVE);
3783 
3784 	/* if reaching here via the fastopen/sendmsg path, the caller already
3785 	 * acquired the subflow socket lock, too.
3786 	 */
3787 	if (!msk->fastopening)
3788 		lock_sock(ssk);
3789 
3790 	/* the following mirrors closely a very small chunk of code from
3791 	 * __inet_stream_connect()
3792 	 */
3793 	if (ssk->sk_state != TCP_CLOSE)
3794 		goto out;
3795 
3796 	if (BPF_CGROUP_PRE_CONNECT_ENABLED(ssk)) {
3797 		err = ssk->sk_prot->pre_connect(ssk, uaddr, addr_len);
3798 		if (err)
3799 			goto out;
3800 	}
3801 
3802 	err = ssk->sk_prot->connect(ssk, uaddr, addr_len);
3803 	if (err < 0)
3804 		goto out;
3805 
3806 	inet_assign_bit(DEFER_CONNECT, sk, inet_test_bit(DEFER_CONNECT, ssk));
3807 
3808 out:
3809 	if (!msk->fastopening)
3810 		release_sock(ssk);
3811 
3812 	/* on successful connect, the msk state will be moved to established by
3813 	 * subflow_finish_connect()
3814 	 */
3815 	if (unlikely(err)) {
3816 		/* avoid leaving a dangling token in an unconnected socket */
3817 		mptcp_token_destroy(msk);
3818 		mptcp_set_state(sk, TCP_CLOSE);
3819 		return err;
3820 	}
3821 
3822 	mptcp_copy_inaddrs(sk, ssk);
3823 	return 0;
3824 }
3825 
3826 static struct proto mptcp_prot = {
3827 	.name		= "MPTCP",
3828 	.owner		= THIS_MODULE,
3829 	.init		= mptcp_init_sock,
3830 	.connect	= mptcp_connect,
3831 	.disconnect	= mptcp_disconnect,
3832 	.close		= mptcp_close,
3833 	.setsockopt	= mptcp_setsockopt,
3834 	.getsockopt	= mptcp_getsockopt,
3835 	.shutdown	= mptcp_shutdown,
3836 	.destroy	= mptcp_destroy,
3837 	.sendmsg	= mptcp_sendmsg,
3838 	.ioctl		= mptcp_ioctl,
3839 	.recvmsg	= mptcp_recvmsg,
3840 	.release_cb	= mptcp_release_cb,
3841 	.hash		= mptcp_hash,
3842 	.unhash		= mptcp_unhash,
3843 	.get_port	= mptcp_get_port,
3844 	.forward_alloc_get	= mptcp_forward_alloc_get,
3845 	.stream_memory_free	= mptcp_stream_memory_free,
3846 	.sockets_allocated	= &mptcp_sockets_allocated,
3847 
3848 	.memory_allocated	= &tcp_memory_allocated,
3849 	.per_cpu_fw_alloc	= &tcp_memory_per_cpu_fw_alloc,
3850 
3851 	.memory_pressure	= &tcp_memory_pressure,
3852 	.sysctl_wmem_offset	= offsetof(struct net, ipv4.sysctl_tcp_wmem),
3853 	.sysctl_rmem_offset	= offsetof(struct net, ipv4.sysctl_tcp_rmem),
3854 	.sysctl_mem	= sysctl_tcp_mem,
3855 	.obj_size	= sizeof(struct mptcp_sock),
3856 	.slab_flags	= SLAB_TYPESAFE_BY_RCU,
3857 	.no_autobind	= true,
3858 };
3859 
mptcp_bind(struct socket * sock,struct sockaddr * uaddr,int addr_len)3860 static int mptcp_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
3861 {
3862 	struct mptcp_sock *msk = mptcp_sk(sock->sk);
3863 	struct sock *ssk, *sk = sock->sk;
3864 	int err = -EINVAL;
3865 
3866 	lock_sock(sk);
3867 	ssk = __mptcp_nmpc_sk(msk);
3868 	if (IS_ERR(ssk)) {
3869 		err = PTR_ERR(ssk);
3870 		goto unlock;
3871 	}
3872 
3873 	if (sk->sk_family == AF_INET)
3874 		err = inet_bind_sk(ssk, uaddr, addr_len);
3875 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
3876 	else if (sk->sk_family == AF_INET6)
3877 		err = inet6_bind_sk(ssk, uaddr, addr_len);
3878 #endif
3879 	if (!err)
3880 		mptcp_copy_inaddrs(sk, ssk);
3881 
3882 unlock:
3883 	release_sock(sk);
3884 	return err;
3885 }
3886 
mptcp_listen(struct socket * sock,int backlog)3887 static int mptcp_listen(struct socket *sock, int backlog)
3888 {
3889 	struct mptcp_sock *msk = mptcp_sk(sock->sk);
3890 	struct sock *sk = sock->sk;
3891 	struct sock *ssk;
3892 	int err;
3893 
3894 	pr_debug("msk=%p\n", msk);
3895 
3896 	lock_sock(sk);
3897 
3898 	err = -EINVAL;
3899 	if (sock->state != SS_UNCONNECTED || sock->type != SOCK_STREAM)
3900 		goto unlock;
3901 
3902 	ssk = __mptcp_nmpc_sk(msk);
3903 	if (IS_ERR(ssk)) {
3904 		err = PTR_ERR(ssk);
3905 		goto unlock;
3906 	}
3907 
3908 	mptcp_set_state(sk, TCP_LISTEN);
3909 	sock_set_flag(sk, SOCK_RCU_FREE);
3910 
3911 	lock_sock(ssk);
3912 	err = __inet_listen_sk(ssk, backlog);
3913 	release_sock(ssk);
3914 	mptcp_set_state(sk, inet_sk_state_load(ssk));
3915 
3916 	if (!err) {
3917 		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
3918 		mptcp_copy_inaddrs(sk, ssk);
3919 		mptcp_event_pm_listener(ssk, MPTCP_EVENT_LISTENER_CREATED);
3920 	}
3921 
3922 unlock:
3923 	release_sock(sk);
3924 	return err;
3925 }
3926 
mptcp_stream_accept(struct socket * sock,struct socket * newsock,struct proto_accept_arg * arg)3927 static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
3928 			       struct proto_accept_arg *arg)
3929 {
3930 	struct mptcp_sock *msk = mptcp_sk(sock->sk);
3931 	struct sock *ssk, *newsk;
3932 
3933 	pr_debug("msk=%p\n", msk);
3934 
3935 	/* Buggy applications can call accept on socket states other then LISTEN
3936 	 * but no need to allocate the first subflow just to error out.
3937 	 */
3938 	ssk = READ_ONCE(msk->first);
3939 	if (!ssk)
3940 		return -EINVAL;
3941 
3942 	pr_debug("ssk=%p, listener=%p\n", ssk, mptcp_subflow_ctx(ssk));
3943 	newsk = inet_csk_accept(ssk, arg);
3944 	if (!newsk)
3945 		return arg->err;
3946 
3947 	pr_debug("newsk=%p, subflow is mptcp=%d\n", newsk, sk_is_mptcp(newsk));
3948 	if (sk_is_mptcp(newsk)) {
3949 		struct mptcp_subflow_context *subflow;
3950 		struct sock *new_mptcp_sock;
3951 
3952 		subflow = mptcp_subflow_ctx(newsk);
3953 		new_mptcp_sock = subflow->conn;
3954 
3955 		/* is_mptcp should be false if subflow->conn is missing, see
3956 		 * subflow_syn_recv_sock()
3957 		 */
3958 		if (WARN_ON_ONCE(!new_mptcp_sock)) {
3959 			tcp_sk(newsk)->is_mptcp = 0;
3960 			goto tcpfallback;
3961 		}
3962 
3963 		newsk = new_mptcp_sock;
3964 		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPCAPABLEPASSIVEACK);
3965 
3966 		newsk->sk_kern_sock = arg->kern;
3967 		lock_sock(newsk);
3968 		__inet_accept(sock, newsock, newsk);
3969 
3970 		set_bit(SOCK_CUSTOM_SOCKOPT, &newsock->flags);
3971 		msk = mptcp_sk(newsk);
3972 		msk->in_accept_queue = 0;
3973 
3974 		/* set ssk->sk_socket of accept()ed flows to mptcp socket.
3975 		 * This is needed so NOSPACE flag can be set from tcp stack.
3976 		 */
3977 		mptcp_for_each_subflow(msk, subflow) {
3978 			struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
3979 
3980 			if (!ssk->sk_socket)
3981 				mptcp_sock_graft(ssk, newsock);
3982 		}
3983 
3984 		/* Do late cleanup for the first subflow as necessary. Also
3985 		 * deal with bad peers not doing a complete shutdown.
3986 		 */
3987 		if (unlikely(inet_sk_state_load(msk->first) == TCP_CLOSE)) {
3988 			__mptcp_close_ssk(newsk, msk->first,
3989 					  mptcp_subflow_ctx(msk->first), 0);
3990 			if (unlikely(list_is_singular(&msk->conn_list)))
3991 				mptcp_set_state(newsk, TCP_CLOSE);
3992 		}
3993 	} else {
3994 tcpfallback:
3995 		newsk->sk_kern_sock = arg->kern;
3996 		lock_sock(newsk);
3997 		__inet_accept(sock, newsock, newsk);
3998 		/* we are being invoked after accepting a non-mp-capable
3999 		 * flow: sk is a tcp_sk, not an mptcp one.
4000 		 *
4001 		 * Hand the socket over to tcp so all further socket ops
4002 		 * bypass mptcp.
4003 		 */
4004 		WRITE_ONCE(newsock->sk->sk_socket->ops,
4005 			   mptcp_fallback_tcp_ops(newsock->sk));
4006 	}
4007 	release_sock(newsk);
4008 
4009 	return 0;
4010 }
4011 
mptcp_check_writeable(struct mptcp_sock * msk)4012 static __poll_t mptcp_check_writeable(struct mptcp_sock *msk)
4013 {
4014 	struct sock *sk = (struct sock *)msk;
4015 
4016 	if (__mptcp_stream_is_writeable(sk, 1))
4017 		return EPOLLOUT | EPOLLWRNORM;
4018 
4019 	set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
4020 	smp_mb__after_atomic(); /* NOSPACE is changed by mptcp_write_space() */
4021 	if (__mptcp_stream_is_writeable(sk, 1))
4022 		return EPOLLOUT | EPOLLWRNORM;
4023 
4024 	return 0;
4025 }
4026 
mptcp_poll(struct file * file,struct socket * sock,struct poll_table_struct * wait)4027 static __poll_t mptcp_poll(struct file *file, struct socket *sock,
4028 			   struct poll_table_struct *wait)
4029 {
4030 	struct sock *sk = sock->sk;
4031 	struct mptcp_sock *msk;
4032 	__poll_t mask = 0;
4033 	u8 shutdown;
4034 	int state;
4035 
4036 	msk = mptcp_sk(sk);
4037 	sock_poll_wait(file, sock, wait);
4038 
4039 	state = inet_sk_state_load(sk);
4040 	pr_debug("msk=%p state=%d flags=%lx\n", msk, state, msk->flags);
4041 	if (state == TCP_LISTEN) {
4042 		struct sock *ssk = READ_ONCE(msk->first);
4043 
4044 		if (WARN_ON_ONCE(!ssk))
4045 			return 0;
4046 
4047 		return inet_csk_listen_poll(ssk);
4048 	}
4049 
4050 	shutdown = READ_ONCE(sk->sk_shutdown);
4051 	if (shutdown == SHUTDOWN_MASK || state == TCP_CLOSE)
4052 		mask |= EPOLLHUP;
4053 	if (shutdown & RCV_SHUTDOWN)
4054 		mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP;
4055 
4056 	if (state != TCP_SYN_SENT && state != TCP_SYN_RECV) {
4057 		mask |= mptcp_check_readable(sk);
4058 		if (shutdown & SEND_SHUTDOWN)
4059 			mask |= EPOLLOUT | EPOLLWRNORM;
4060 		else
4061 			mask |= mptcp_check_writeable(msk);
4062 	} else if (state == TCP_SYN_SENT &&
4063 		   inet_test_bit(DEFER_CONNECT, sk)) {
4064 		/* cf tcp_poll() note about TFO */
4065 		mask |= EPOLLOUT | EPOLLWRNORM;
4066 	}
4067 
4068 	/* This barrier is coupled with smp_wmb() in __mptcp_error_report() */
4069 	smp_rmb();
4070 	if (READ_ONCE(sk->sk_err))
4071 		mask |= EPOLLERR;
4072 
4073 	return mask;
4074 }
4075 
4076 static const struct proto_ops mptcp_stream_ops = {
4077 	.family		   = PF_INET,
4078 	.owner		   = THIS_MODULE,
4079 	.release	   = inet_release,
4080 	.bind		   = mptcp_bind,
4081 	.connect	   = inet_stream_connect,
4082 	.socketpair	   = sock_no_socketpair,
4083 	.accept		   = mptcp_stream_accept,
4084 	.getname	   = inet_getname,
4085 	.poll		   = mptcp_poll,
4086 	.ioctl		   = inet_ioctl,
4087 	.gettstamp	   = sock_gettstamp,
4088 	.listen		   = mptcp_listen,
4089 	.shutdown	   = inet_shutdown,
4090 	.setsockopt	   = sock_common_setsockopt,
4091 	.getsockopt	   = sock_common_getsockopt,
4092 	.sendmsg	   = inet_sendmsg,
4093 	.recvmsg	   = inet_recvmsg,
4094 	.mmap		   = sock_no_mmap,
4095 	.set_rcvlowat	   = mptcp_set_rcvlowat,
4096 };
4097 
4098 static struct inet_protosw mptcp_protosw = {
4099 	.type		= SOCK_STREAM,
4100 	.protocol	= IPPROTO_MPTCP,
4101 	.prot		= &mptcp_prot,
4102 	.ops		= &mptcp_stream_ops,
4103 	.flags		= INET_PROTOSW_ICSK,
4104 };
4105 
mptcp_napi_poll(struct napi_struct * napi,int budget)4106 static int mptcp_napi_poll(struct napi_struct *napi, int budget)
4107 {
4108 	struct mptcp_delegated_action *delegated;
4109 	struct mptcp_subflow_context *subflow;
4110 	int work_done = 0;
4111 
4112 	delegated = container_of(napi, struct mptcp_delegated_action, napi);
4113 	while ((subflow = mptcp_subflow_delegated_next(delegated)) != NULL) {
4114 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
4115 
4116 		bh_lock_sock_nested(ssk);
4117 		if (!sock_owned_by_user(ssk)) {
4118 			mptcp_subflow_process_delegated(ssk, xchg(&subflow->delegated_status, 0));
4119 		} else {
4120 			/* tcp_release_cb_override already processed
4121 			 * the action or will do at next release_sock().
4122 			 * In both case must dequeue the subflow here - on the same
4123 			 * CPU that scheduled it.
4124 			 */
4125 			smp_wmb();
4126 			clear_bit(MPTCP_DELEGATE_SCHEDULED, &subflow->delegated_status);
4127 		}
4128 		bh_unlock_sock(ssk);
4129 		sock_put(ssk);
4130 
4131 		if (++work_done == budget)
4132 			return budget;
4133 	}
4134 
4135 	/* always provide a 0 'work_done' argument, so that napi_complete_done
4136 	 * will not try accessing the NULL napi->dev ptr
4137 	 */
4138 	napi_complete_done(napi, 0);
4139 	return work_done;
4140 }
4141 
mptcp_proto_init(void)4142 void __init mptcp_proto_init(void)
4143 {
4144 	struct mptcp_delegated_action *delegated;
4145 	int cpu;
4146 
4147 	mptcp_prot.h.hashinfo = tcp_prot.h.hashinfo;
4148 
4149 	if (percpu_counter_init(&mptcp_sockets_allocated, 0, GFP_KERNEL))
4150 		panic("Failed to allocate MPTCP pcpu counter\n");
4151 
4152 	mptcp_napi_dev = alloc_netdev_dummy(0);
4153 	if (!mptcp_napi_dev)
4154 		panic("Failed to allocate MPTCP dummy netdev\n");
4155 	for_each_possible_cpu(cpu) {
4156 		delegated = per_cpu_ptr(&mptcp_delegated_actions, cpu);
4157 		INIT_LIST_HEAD(&delegated->head);
4158 		netif_napi_add_tx(mptcp_napi_dev, &delegated->napi,
4159 				  mptcp_napi_poll);
4160 		napi_enable(&delegated->napi);
4161 	}
4162 
4163 	mptcp_subflow_init();
4164 	mptcp_pm_init();
4165 	mptcp_sched_init();
4166 	mptcp_token_init();
4167 
4168 	if (proto_register(&mptcp_prot, 1) != 0)
4169 		panic("Failed to register MPTCP proto.\n");
4170 
4171 	inet_register_protosw(&mptcp_protosw);
4172 
4173 	BUILD_BUG_ON(sizeof(struct mptcp_skb_cb) > sizeof_field(struct sk_buff, cb));
4174 }
4175 
4176 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
4177 static const struct proto_ops mptcp_v6_stream_ops = {
4178 	.family		   = PF_INET6,
4179 	.owner		   = THIS_MODULE,
4180 	.release	   = inet6_release,
4181 	.bind		   = mptcp_bind,
4182 	.connect	   = inet_stream_connect,
4183 	.socketpair	   = sock_no_socketpair,
4184 	.accept		   = mptcp_stream_accept,
4185 	.getname	   = inet6_getname,
4186 	.poll		   = mptcp_poll,
4187 	.ioctl		   = inet6_ioctl,
4188 	.gettstamp	   = sock_gettstamp,
4189 	.listen		   = mptcp_listen,
4190 	.shutdown	   = inet_shutdown,
4191 	.setsockopt	   = sock_common_setsockopt,
4192 	.getsockopt	   = sock_common_getsockopt,
4193 	.sendmsg	   = inet6_sendmsg,
4194 	.recvmsg	   = inet6_recvmsg,
4195 	.mmap		   = sock_no_mmap,
4196 #ifdef CONFIG_COMPAT
4197 	.compat_ioctl	   = inet6_compat_ioctl,
4198 #endif
4199 	.set_rcvlowat	   = mptcp_set_rcvlowat,
4200 };
4201 
4202 static struct proto mptcp_v6_prot;
4203 
4204 static struct inet_protosw mptcp_v6_protosw = {
4205 	.type		= SOCK_STREAM,
4206 	.protocol	= IPPROTO_MPTCP,
4207 	.prot		= &mptcp_v6_prot,
4208 	.ops		= &mptcp_v6_stream_ops,
4209 	.flags		= INET_PROTOSW_ICSK,
4210 };
4211 
mptcp_proto_v6_init(void)4212 int __init mptcp_proto_v6_init(void)
4213 {
4214 	int err;
4215 
4216 	mptcp_v6_prot = mptcp_prot;
4217 	strscpy(mptcp_v6_prot.name, "MPTCPv6", sizeof(mptcp_v6_prot.name));
4218 	mptcp_v6_prot.slab = NULL;
4219 	mptcp_v6_prot.obj_size = sizeof(struct mptcp6_sock);
4220 	mptcp_v6_prot.ipv6_pinfo_offset = offsetof(struct mptcp6_sock, np);
4221 
4222 	err = proto_register(&mptcp_v6_prot, 1);
4223 	if (err)
4224 		return err;
4225 
4226 	err = inet6_register_protosw(&mptcp_v6_protosw);
4227 	if (err)
4228 		proto_unregister(&mptcp_v6_prot);
4229 
4230 	return err;
4231 }
4232 #endif
4233