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Linux 4.19-rc7
[linux-2.6/btrfs-unstable.git] / net / kcm / kcmsock.c
blob571d824e4e2499e1f591701ed0e25c4aff73b00a
1 /*
2 * Kernel Connection Multiplexor
3 *
4 * Copyright (c) 2016 Tom Herbert <tom@herbertland.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2
8 * as published by the Free Software Foundation.
9 */
10
11 #include <linux/bpf.h>
12 #include <linux/errno.h>
13 #include <linux/errqueue.h>
14 #include <linux/file.h>
15 #include <linux/in.h>
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/net.h>
19 #include <linux/netdevice.h>
20 #include <linux/poll.h>
21 #include <linux/rculist.h>
22 #include <linux/skbuff.h>
23 #include <linux/socket.h>
24 #include <linux/uaccess.h>
25 #include <linux/workqueue.h>
26 #include <linux/syscalls.h>
27 #include <linux/sched/signal.h>
28
29 #include <net/kcm.h>
30 #include <net/netns/generic.h>
31 #include <net/sock.h>
32 #include <uapi/linux/kcm.h>
33
34 unsigned int kcm_net_id;
35
36 static struct kmem_cache *kcm_psockp __read_mostly;
37 static struct kmem_cache *kcm_muxp __read_mostly;
38 static struct workqueue_struct *kcm_wq;
39
40 static inline struct kcm_sock *kcm_sk(const struct sock *sk)
41 {
42 return (struct kcm_sock *)sk;
43 }
44
45 static inline struct kcm_tx_msg *kcm_tx_msg(struct sk_buff *skb)
46 {
47 return (struct kcm_tx_msg *)skb->cb;
48 }
49
50 static void report_csk_error(struct sock *csk, int err)
51 {
52 csk->sk_err = EPIPE;
53 csk->sk_error_report(csk);
54 }
55
56 static void kcm_abort_tx_psock(struct kcm_psock *psock, int err,
57 bool wakeup_kcm)
58 {
59 struct sock *csk = psock->sk;
60 struct kcm_mux *mux = psock->mux;
61
62 /* Unrecoverable error in transmit */
63
64 spin_lock_bh(&mux->lock);
65
66 if (psock->tx_stopped) {
67 spin_unlock_bh(&mux->lock);
68 return;
69 }
70
71 psock->tx_stopped = 1;
72 KCM_STATS_INCR(psock->stats.tx_aborts);
73
74 if (!psock->tx_kcm) {
75 /* Take off psocks_avail list */
76 list_del(&psock->psock_avail_list);
77 } else if (wakeup_kcm) {
78 /* In this case psock is being aborted while outside of
79 * write_msgs and psock is reserved. Schedule tx_work
80 * to handle the failure there. Need to commit tx_stopped
81 * before queuing work.
82 */
83 smp_mb();
84
85 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
86 }
87
88 spin_unlock_bh(&mux->lock);
89
90 /* Report error on lower socket */
91 report_csk_error(csk, err);
92 }
93
94 /* RX mux lock held. */
95 static void kcm_update_rx_mux_stats(struct kcm_mux *mux,
96 struct kcm_psock *psock)
97 {
98 STRP_STATS_ADD(mux->stats.rx_bytes,
99 psock->strp.stats.bytes -
100 psock->saved_rx_bytes);
101 mux->stats.rx_msgs +=
102 psock->strp.stats.msgs - psock->saved_rx_msgs;
103 psock->saved_rx_msgs = psock->strp.stats.msgs;
104 psock->saved_rx_bytes = psock->strp.stats.bytes;
105 }
106
107 static void kcm_update_tx_mux_stats(struct kcm_mux *mux,
108 struct kcm_psock *psock)
109 {
110 KCM_STATS_ADD(mux->stats.tx_bytes,
111 psock->stats.tx_bytes - psock->saved_tx_bytes);
112 mux->stats.tx_msgs +=
113 psock->stats.tx_msgs - psock->saved_tx_msgs;
114 psock->saved_tx_msgs = psock->stats.tx_msgs;
115 psock->saved_tx_bytes = psock->stats.tx_bytes;
116 }
117
118 static int kcm_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
119
120 /* KCM is ready to receive messages on its queue-- either the KCM is new or
121 * has become unblocked after being blocked on full socket buffer. Queue any
122 * pending ready messages on a psock. RX mux lock held.
123 */
124 static void kcm_rcv_ready(struct kcm_sock *kcm)
125 {
126 struct kcm_mux *mux = kcm->mux;
127 struct kcm_psock *psock;
128 struct sk_buff *skb;
129
130 if (unlikely(kcm->rx_wait || kcm->rx_psock || kcm->rx_disabled))
131 return;
132
133 while (unlikely((skb = __skb_dequeue(&mux->rx_hold_queue)))) {
134 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
135 /* Assuming buffer limit has been reached */
136 skb_queue_head(&mux->rx_hold_queue, skb);
137 WARN_ON(!sk_rmem_alloc_get(&kcm->sk));
138 return;
139 }
140 }
141
142 while (!list_empty(&mux->psocks_ready)) {
143 psock = list_first_entry(&mux->psocks_ready, struct kcm_psock,
144 psock_ready_list);
145
146 if (kcm_queue_rcv_skb(&kcm->sk, psock->ready_rx_msg)) {
147 /* Assuming buffer limit has been reached */
148 WARN_ON(!sk_rmem_alloc_get(&kcm->sk));
149 return;
150 }
151
152 /* Consumed the ready message on the psock. Schedule rx_work to
153 * get more messages.
154 */
155 list_del(&psock->psock_ready_list);
156 psock->ready_rx_msg = NULL;
157 /* Commit clearing of ready_rx_msg for queuing work */
158 smp_mb();
159
160 strp_unpause(&psock->strp);
161 strp_check_rcv(&psock->strp);
162 }
163
164 /* Buffer limit is okay now, add to ready list */
165 list_add_tail(&kcm->wait_rx_list,
166 &kcm->mux->kcm_rx_waiters);
167 kcm->rx_wait = true;
168 }
169
170 static void kcm_rfree(struct sk_buff *skb)
171 {
172 struct sock *sk = skb->sk;
173 struct kcm_sock *kcm = kcm_sk(sk);
174 struct kcm_mux *mux = kcm->mux;
175 unsigned int len = skb->truesize;
176
177 sk_mem_uncharge(sk, len);
178 atomic_sub(len, &sk->sk_rmem_alloc);
179
180 /* For reading rx_wait and rx_psock without holding lock */
181 smp_mb__after_atomic();
182
183 if (!kcm->rx_wait && !kcm->rx_psock &&
184 sk_rmem_alloc_get(sk) < sk->sk_rcvlowat) {
185 spin_lock_bh(&mux->rx_lock);
186 kcm_rcv_ready(kcm);
187 spin_unlock_bh(&mux->rx_lock);
188 }
189 }
190
191 static int kcm_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
192 {
193 struct sk_buff_head *list = &sk->sk_receive_queue;
194
195 if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
196 return -ENOMEM;
197
198 if (!sk_rmem_schedule(sk, skb, skb->truesize))
199 return -ENOBUFS;
200
201 skb->dev = NULL;
202
203 skb_orphan(skb);
204 skb->sk = sk;
205 skb->destructor = kcm_rfree;
206 atomic_add(skb->truesize, &sk->sk_rmem_alloc);
207 sk_mem_charge(sk, skb->truesize);
208
209 skb_queue_tail(list, skb);
210
211 if (!sock_flag(sk, SOCK_DEAD))
212 sk->sk_data_ready(sk);
213
214 return 0;
215 }
216
217 /* Requeue received messages for a kcm socket to other kcm sockets. This is
218 * called with a kcm socket is receive disabled.
219 * RX mux lock held.
220 */
221 static void requeue_rx_msgs(struct kcm_mux *mux, struct sk_buff_head *head)
222 {
223 struct sk_buff *skb;
224 struct kcm_sock *kcm;
225
226 while ((skb = __skb_dequeue(head))) {
227 /* Reset destructor to avoid calling kcm_rcv_ready */
228 skb->destructor = sock_rfree;
229 skb_orphan(skb);
230 try_again:
231 if (list_empty(&mux->kcm_rx_waiters)) {
232 skb_queue_tail(&mux->rx_hold_queue, skb);
233 continue;
234 }
235
236 kcm = list_first_entry(&mux->kcm_rx_waiters,
237 struct kcm_sock, wait_rx_list);
238
239 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
240 /* Should mean socket buffer full */
241 list_del(&kcm->wait_rx_list);
242 kcm->rx_wait = false;
243
244 /* Commit rx_wait to read in kcm_free */
245 smp_wmb();
246
247 goto try_again;
248 }
249 }
250 }
251
252 /* Lower sock lock held */
253 static struct kcm_sock *reserve_rx_kcm(struct kcm_psock *psock,
254 struct sk_buff *head)
255 {
256 struct kcm_mux *mux = psock->mux;
257 struct kcm_sock *kcm;
258
259 WARN_ON(psock->ready_rx_msg);
260
261 if (psock->rx_kcm)
262 return psock->rx_kcm;
263
264 spin_lock_bh(&mux->rx_lock);
265
266 if (psock->rx_kcm) {
267 spin_unlock_bh(&mux->rx_lock);
268 return psock->rx_kcm;
269 }
270
271 kcm_update_rx_mux_stats(mux, psock);
272
273 if (list_empty(&mux->kcm_rx_waiters)) {
274 psock->ready_rx_msg = head;
275 strp_pause(&psock->strp);
276 list_add_tail(&psock->psock_ready_list,
277 &mux->psocks_ready);
278 spin_unlock_bh(&mux->rx_lock);
279 return NULL;
280 }
281
282 kcm = list_first_entry(&mux->kcm_rx_waiters,
283 struct kcm_sock, wait_rx_list);
284 list_del(&kcm->wait_rx_list);
285 kcm->rx_wait = false;
286
287 psock->rx_kcm = kcm;
288 kcm->rx_psock = psock;
289
290 spin_unlock_bh(&mux->rx_lock);
291
292 return kcm;
293 }
294
295 static void kcm_done(struct kcm_sock *kcm);
296
297 static void kcm_done_work(struct work_struct *w)
298 {
299 kcm_done(container_of(w, struct kcm_sock, done_work));
300 }
301
302 /* Lower sock held */
303 static void unreserve_rx_kcm(struct kcm_psock *psock,
304 bool rcv_ready)
305 {
306 struct kcm_sock *kcm = psock->rx_kcm;
307 struct kcm_mux *mux = psock->mux;
308
309 if (!kcm)
310 return;
311
312 spin_lock_bh(&mux->rx_lock);
313
314 psock->rx_kcm = NULL;
315 kcm->rx_psock = NULL;
316
317 /* Commit kcm->rx_psock before sk_rmem_alloc_get to sync with
318 * kcm_rfree
319 */
320 smp_mb();
321
322 if (unlikely(kcm->done)) {
323 spin_unlock_bh(&mux->rx_lock);
324
325 /* Need to run kcm_done in a task since we need to qcquire
326 * callback locks which may already be held here.
327 */
328 INIT_WORK(&kcm->done_work, kcm_done_work);
329 schedule_work(&kcm->done_work);
330 return;
331 }
332
333 if (unlikely(kcm->rx_disabled)) {
334 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
335 } else if (rcv_ready || unlikely(!sk_rmem_alloc_get(&kcm->sk))) {
336 /* Check for degenerative race with rx_wait that all
337 * data was dequeued (accounted for in kcm_rfree).
338 */
339 kcm_rcv_ready(kcm);
340 }
341 spin_unlock_bh(&mux->rx_lock);
342 }
343
344 /* Lower sock lock held */
345 static void psock_data_ready(struct sock *sk)
346 {
347 struct kcm_psock *psock;
348
349 read_lock_bh(&sk->sk_callback_lock);
350
351 psock = (struct kcm_psock *)sk->sk_user_data;
352 if (likely(psock))
353 strp_data_ready(&psock->strp);
354
355 read_unlock_bh(&sk->sk_callback_lock);
356 }
357
358 /* Called with lower sock held */
359 static void kcm_rcv_strparser(struct strparser *strp, struct sk_buff *skb)
360 {
361 struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
362 struct kcm_sock *kcm;
363
364 try_queue:
365 kcm = reserve_rx_kcm(psock, skb);
366 if (!kcm) {
367 /* Unable to reserve a KCM, message is held in psock and strp
368 * is paused.
369 */
370 return;
371 }
372
373 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
374 /* Should mean socket buffer full */
375 unreserve_rx_kcm(psock, false);
376 goto try_queue;
377 }
378 }
379
380 static int kcm_parse_func_strparser(struct strparser *strp, struct sk_buff *skb)
381 {
382 struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
383 struct bpf_prog *prog = psock->bpf_prog;
384
385 return (*prog->bpf_func)(skb, prog->insnsi);
386 }
387
388 static int kcm_read_sock_done(struct strparser *strp, int err)
389 {
390 struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
391
392 unreserve_rx_kcm(psock, true);
393
394 return err;
395 }
396
397 static void psock_state_change(struct sock *sk)
398 {
399 /* TCP only does a EPOLLIN for a half close. Do a EPOLLHUP here
400 * since application will normally not poll with EPOLLIN
401 * on the TCP sockets.
402 */
403
404 report_csk_error(sk, EPIPE);
405 }
406
407 static void psock_write_space(struct sock *sk)
408 {
409 struct kcm_psock *psock;
410 struct kcm_mux *mux;
411 struct kcm_sock *kcm;
412
413 read_lock_bh(&sk->sk_callback_lock);
414
415 psock = (struct kcm_psock *)sk->sk_user_data;
416 if (unlikely(!psock))
417 goto out;
418 mux = psock->mux;
419
420 spin_lock_bh(&mux->lock);
421
422 /* Check if the socket is reserved so someone is waiting for sending. */
423 kcm = psock->tx_kcm;
424 if (kcm && !unlikely(kcm->tx_stopped))
425 queue_work(kcm_wq, &kcm->tx_work);
426
427 spin_unlock_bh(&mux->lock);
428 out:
429 read_unlock_bh(&sk->sk_callback_lock);
430 }
431
432 static void unreserve_psock(struct kcm_sock *kcm);
433
434 /* kcm sock is locked. */
435 static struct kcm_psock *reserve_psock(struct kcm_sock *kcm)
436 {
437 struct kcm_mux *mux = kcm->mux;
438 struct kcm_psock *psock;
439
440 psock = kcm->tx_psock;
441
442 smp_rmb(); /* Must read tx_psock before tx_wait */
443
444 if (psock) {
445 WARN_ON(kcm->tx_wait);
446 if (unlikely(psock->tx_stopped))
447 unreserve_psock(kcm);
448 else
449 return kcm->tx_psock;
450 }
451
452 spin_lock_bh(&mux->lock);
453
454 /* Check again under lock to see if psock was reserved for this
455 * psock via psock_unreserve.
456 */
457 psock = kcm->tx_psock;
458 if (unlikely(psock)) {
459 WARN_ON(kcm->tx_wait);
460 spin_unlock_bh(&mux->lock);
461 return kcm->tx_psock;
462 }
463
464 if (!list_empty(&mux->psocks_avail)) {
465 psock = list_first_entry(&mux->psocks_avail,
466 struct kcm_psock,
467 psock_avail_list);
468 list_del(&psock->psock_avail_list);
469 if (kcm->tx_wait) {
470 list_del(&kcm->wait_psock_list);
471 kcm->tx_wait = false;
472 }
473 kcm->tx_psock = psock;
474 psock->tx_kcm = kcm;
475 KCM_STATS_INCR(psock->stats.reserved);
476 } else if (!kcm->tx_wait) {
477 list_add_tail(&kcm->wait_psock_list,
478 &mux->kcm_tx_waiters);
479 kcm->tx_wait = true;
480 }
481
482 spin_unlock_bh(&mux->lock);
483
484 return psock;
485 }
486
487 /* mux lock held */
488 static void psock_now_avail(struct kcm_psock *psock)
489 {
490 struct kcm_mux *mux = psock->mux;
491 struct kcm_sock *kcm;
492
493 if (list_empty(&mux->kcm_tx_waiters)) {
494 list_add_tail(&psock->psock_avail_list,
495 &mux->psocks_avail);
496 } else {
497 kcm = list_first_entry(&mux->kcm_tx_waiters,
498 struct kcm_sock,
499 wait_psock_list);
500 list_del(&kcm->wait_psock_list);
501 kcm->tx_wait = false;
502 psock->tx_kcm = kcm;
503
504 /* Commit before changing tx_psock since that is read in
505 * reserve_psock before queuing work.
506 */
507 smp_mb();
508
509 kcm->tx_psock = psock;
510 KCM_STATS_INCR(psock->stats.reserved);
511 queue_work(kcm_wq, &kcm->tx_work);
512 }
513 }
514
515 /* kcm sock is locked. */
516 static void unreserve_psock(struct kcm_sock *kcm)
517 {
518 struct kcm_psock *psock;
519 struct kcm_mux *mux = kcm->mux;
520
521 spin_lock_bh(&mux->lock);
522
523 psock = kcm->tx_psock;
524
525 if (WARN_ON(!psock)) {
526 spin_unlock_bh(&mux->lock);
527 return;
528 }
529
530 smp_rmb(); /* Read tx_psock before tx_wait */
531
532 kcm_update_tx_mux_stats(mux, psock);
533
534 WARN_ON(kcm->tx_wait);
535
536 kcm->tx_psock = NULL;
537 psock->tx_kcm = NULL;
538 KCM_STATS_INCR(psock->stats.unreserved);
539
540 if (unlikely(psock->tx_stopped)) {
541 if (psock->done) {
542 /* Deferred free */
543 list_del(&psock->psock_list);
544 mux->psocks_cnt--;
545 sock_put(psock->sk);
546 fput(psock->sk->sk_socket->file);
547 kmem_cache_free(kcm_psockp, psock);
548 }
549
550 /* Don't put back on available list */
551
552 spin_unlock_bh(&mux->lock);
553
554 return;
555 }
556
557 psock_now_avail(psock);
558
559 spin_unlock_bh(&mux->lock);
560 }
561
562 static void kcm_report_tx_retry(struct kcm_sock *kcm)
563 {
564 struct kcm_mux *mux = kcm->mux;
565
566 spin_lock_bh(&mux->lock);
567 KCM_STATS_INCR(mux->stats.tx_retries);
568 spin_unlock_bh(&mux->lock);
569 }
570
571 /* Write any messages ready on the kcm socket. Called with kcm sock lock
572 * held. Return bytes actually sent or error.
573 */
574 static int kcm_write_msgs(struct kcm_sock *kcm)
575 {
576 struct sock *sk = &kcm->sk;
577 struct kcm_psock *psock;
578 struct sk_buff *skb, *head;
579 struct kcm_tx_msg *txm;
580 unsigned short fragidx, frag_offset;
581 unsigned int sent, total_sent = 0;
582 int ret = 0;
583
584 kcm->tx_wait_more = false;
585 psock = kcm->tx_psock;
586 if (unlikely(psock && psock->tx_stopped)) {
587 /* A reserved psock was aborted asynchronously. Unreserve
588 * it and we'll retry the message.
589 */
590 unreserve_psock(kcm);
591 kcm_report_tx_retry(kcm);
592 if (skb_queue_empty(&sk->sk_write_queue))
593 return 0;
594
595 kcm_tx_msg(skb_peek(&sk->sk_write_queue))->sent = 0;
596
597 } else if (skb_queue_empty(&sk->sk_write_queue)) {
598 return 0;
599 }
600
601 head = skb_peek(&sk->sk_write_queue);
602 txm = kcm_tx_msg(head);
603
604 if (txm->sent) {
605 /* Send of first skbuff in queue already in progress */
606 if (WARN_ON(!psock)) {
607 ret = -EINVAL;
608 goto out;
609 }
610 sent = txm->sent;
611 frag_offset = txm->frag_offset;
612 fragidx = txm->fragidx;
613 skb = txm->frag_skb;
614
615 goto do_frag;
616 }
617
618 try_again:
619 psock = reserve_psock(kcm);
620 if (!psock)
621 goto out;
622
623 do {
624 skb = head;
625 txm = kcm_tx_msg(head);
626 sent = 0;
627
628 do_frag_list:
629 if (WARN_ON(!skb_shinfo(skb)->nr_frags)) {
630 ret = -EINVAL;
631 goto out;
632 }
633
634 for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags;
635 fragidx++) {
636 skb_frag_t *frag;
637
638 frag_offset = 0;
639 do_frag:
640 frag = &skb_shinfo(skb)->frags[fragidx];
641 if (WARN_ON(!frag->size)) {
642 ret = -EINVAL;
643 goto out;
644 }
645
646 ret = kernel_sendpage(psock->sk->sk_socket,
647 frag->page.p,
648 frag->page_offset + frag_offset,
649 frag->size - frag_offset,
650 MSG_DONTWAIT);
651 if (ret <= 0) {
652 if (ret == -EAGAIN) {
653 /* Save state to try again when there's
654 * write space on the socket
655 */
656 txm->sent = sent;
657 txm->frag_offset = frag_offset;
658 txm->fragidx = fragidx;
659 txm->frag_skb = skb;
660
661 ret = 0;
662 goto out;
663 }
664
665 /* Hard failure in sending message, abort this
666 * psock since it has lost framing
667 * synchonization and retry sending the
668 * message from the beginning.
669 */
670 kcm_abort_tx_psock(psock, ret ? -ret : EPIPE,
671 true);
672 unreserve_psock(kcm);
673
674 txm->sent = 0;
675 kcm_report_tx_retry(kcm);
676 ret = 0;
677
678 goto try_again;
679 }
680
681 sent += ret;
682 frag_offset += ret;
683 KCM_STATS_ADD(psock->stats.tx_bytes, ret);
684 if (frag_offset < frag->size) {
685 /* Not finished with this frag */
686 goto do_frag;
687 }
688 }
689
690 if (skb == head) {
691 if (skb_has_frag_list(skb)) {
692 skb = skb_shinfo(skb)->frag_list;
693 goto do_frag_list;
694 }
695 } else if (skb->next) {
696 skb = skb->next;
697 goto do_frag_list;
698 }
699
700 /* Successfully sent the whole packet, account for it. */
701 skb_dequeue(&sk->sk_write_queue);
702 kfree_skb(head);
703 sk->sk_wmem_queued -= sent;
704 total_sent += sent;
705 KCM_STATS_INCR(psock->stats.tx_msgs);
706 } while ((head = skb_peek(&sk->sk_write_queue)));
707 out:
708 if (!head) {
709 /* Done with all queued messages. */
710 WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
711 unreserve_psock(kcm);
712 }
713
714 /* Check if write space is available */
715 sk->sk_write_space(sk);
716
717 return total_sent ? : ret;
718 }
719
720 static void kcm_tx_work(struct work_struct *w)
721 {
722 struct kcm_sock *kcm = container_of(w, struct kcm_sock, tx_work);
723 struct sock *sk = &kcm->sk;
724 int err;
725
726 lock_sock(sk);
727
728 /* Primarily for SOCK_DGRAM sockets, also handle asynchronous tx
729 * aborts
730 */
731 err = kcm_write_msgs(kcm);
732 if (err < 0) {
733 /* Hard failure in write, report error on KCM socket */
734 pr_warn("KCM: Hard failure on kcm_write_msgs %d\n", err);
735 report_csk_error(&kcm->sk, -err);
736 goto out;
737 }
738
739 /* Primarily for SOCK_SEQPACKET sockets */
740 if (likely(sk->sk_socket) &&
741 test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
742 clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
743 sk->sk_write_space(sk);
744 }
745
746 out:
747 release_sock(sk);
748 }
749
750 static void kcm_push(struct kcm_sock *kcm)
751 {
752 if (kcm->tx_wait_more)
753 kcm_write_msgs(kcm);
754 }
755
756 static ssize_t kcm_sendpage(struct socket *sock, struct page *page,
757 int offset, size_t size, int flags)
758
759 {
760 struct sock *sk = sock->sk;
761 struct kcm_sock *kcm = kcm_sk(sk);
762 struct sk_buff *skb = NULL, *head = NULL;
763 long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
764 bool eor;
765 int err = 0;
766 int i;
767
768 if (flags & MSG_SENDPAGE_NOTLAST)
769 flags |= MSG_MORE;
770
771 /* No MSG_EOR from splice, only look at MSG_MORE */
772 eor = !(flags & MSG_MORE);
773
774 lock_sock(sk);
775
776 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
777
778 err = -EPIPE;
779 if (sk->sk_err)
780 goto out_error;
781
782 if (kcm->seq_skb) {
783 /* Previously opened message */
784 head = kcm->seq_skb;
785 skb = kcm_tx_msg(head)->last_skb;
786 i = skb_shinfo(skb)->nr_frags;
787
788 if (skb_can_coalesce(skb, i, page, offset)) {
789 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
790 skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
791 goto coalesced;
792 }
793
794 if (i >= MAX_SKB_FRAGS) {
795 struct sk_buff *tskb;
796
797 tskb = alloc_skb(0, sk->sk_allocation);
798 while (!tskb) {
799 kcm_push(kcm);
800 err = sk_stream_wait_memory(sk, &timeo);
801 if (err)
802 goto out_error;
803 }
804
805 if (head == skb)
806 skb_shinfo(head)->frag_list = tskb;
807 else
808 skb->next = tskb;
809
810 skb = tskb;
811 skb->ip_summed = CHECKSUM_UNNECESSARY;
812 i = 0;
813 }
814 } else {
815 /* Call the sk_stream functions to manage the sndbuf mem. */
816 if (!sk_stream_memory_free(sk)) {
817 kcm_push(kcm);
818 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
819 err = sk_stream_wait_memory(sk, &timeo);
820 if (err)
821 goto out_error;
822 }
823
824 head = alloc_skb(0, sk->sk_allocation);
825 while (!head) {
826 kcm_push(kcm);
827 err = sk_stream_wait_memory(sk, &timeo);
828 if (err)
829 goto out_error;
830 }
831
832 skb = head;
833 i = 0;
834 }
835
836 get_page(page);
837 skb_fill_page_desc(skb, i, page, offset, size);
838 skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
839
840 coalesced:
841 skb->len += size;
842 skb->data_len += size;
843 skb->truesize += size;
844 sk->sk_wmem_queued += size;
845 sk_mem_charge(sk, size);
846
847 if (head != skb) {
848 head->len += size;
849 head->data_len += size;
850 head->truesize += size;
851 }
852
853 if (eor) {
854 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
855
856 /* Message complete, queue it on send buffer */
857 __skb_queue_tail(&sk->sk_write_queue, head);
858 kcm->seq_skb = NULL;
859 KCM_STATS_INCR(kcm->stats.tx_msgs);
860
861 if (flags & MSG_BATCH) {
862 kcm->tx_wait_more = true;
863 } else if (kcm->tx_wait_more || not_busy) {
864 err = kcm_write_msgs(kcm);
865 if (err < 0) {
866 /* We got a hard error in write_msgs but have
867 * already queued this message. Report an error
868 * in the socket, but don't affect return value
869 * from sendmsg
870 */
871 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
872 report_csk_error(&kcm->sk, -err);
873 }
874 }
875 } else {
876 /* Message not complete, save state */
877 kcm->seq_skb = head;
878 kcm_tx_msg(head)->last_skb = skb;
879 }
880
881 KCM_STATS_ADD(kcm->stats.tx_bytes, size);
882
883 release_sock(sk);
884 return size;
885
886 out_error:
887 kcm_push(kcm);
888
889 err = sk_stream_error(sk, flags, err);
890
891 /* make sure we wake any epoll edge trigger waiter */
892 if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
893 sk->sk_write_space(sk);
894
895 release_sock(sk);
896 return err;
897 }
898
899 static int kcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
900 {
901 struct sock *sk = sock->sk;
902 struct kcm_sock *kcm = kcm_sk(sk);
903 struct sk_buff *skb = NULL, *head = NULL;
904 size_t copy, copied = 0;
905 long timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
906 int eor = (sock->type == SOCK_DGRAM) ?
907 !(msg->msg_flags & MSG_MORE) : !!(msg->msg_flags & MSG_EOR);
908 int err = -EPIPE;
909
910 lock_sock(sk);
911
912 /* Per tcp_sendmsg this should be in poll */
913 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
914
915 if (sk->sk_err)
916 goto out_error;
917
918 if (kcm->seq_skb) {
919 /* Previously opened message */
920 head = kcm->seq_skb;
921 skb = kcm_tx_msg(head)->last_skb;
922 goto start;
923 }
924
925 /* Call the sk_stream functions to manage the sndbuf mem. */
926 if (!sk_stream_memory_free(sk)) {
927 kcm_push(kcm);
928 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
929 err = sk_stream_wait_memory(sk, &timeo);
930 if (err)
931 goto out_error;
932 }
933
934 if (msg_data_left(msg)) {
935 /* New message, alloc head skb */
936 head = alloc_skb(0, sk->sk_allocation);
937 while (!head) {
938 kcm_push(kcm);
939 err = sk_stream_wait_memory(sk, &timeo);
940 if (err)
941 goto out_error;
942
943 head = alloc_skb(0, sk->sk_allocation);
944 }
945
946 skb = head;
947
948 /* Set ip_summed to CHECKSUM_UNNECESSARY to avoid calling
949 * csum_and_copy_from_iter from skb_do_copy_data_nocache.
950 */
951 skb->ip_summed = CHECKSUM_UNNECESSARY;
952 }
953
954 start:
955 while (msg_data_left(msg)) {
956 bool merge = true;
957 int i = skb_shinfo(skb)->nr_frags;
958 struct page_frag *pfrag = sk_page_frag(sk);
959
960 if (!sk_page_frag_refill(sk, pfrag))
961 goto wait_for_memory;
962
963 if (!skb_can_coalesce(skb, i, pfrag->page,
964 pfrag->offset)) {
965 if (i == MAX_SKB_FRAGS) {
966 struct sk_buff *tskb;
967
968 tskb = alloc_skb(0, sk->sk_allocation);
969 if (!tskb)
970 goto wait_for_memory;
971
972 if (head == skb)
973 skb_shinfo(head)->frag_list = tskb;
974 else
975 skb->next = tskb;
976
977 skb = tskb;
978 skb->ip_summed = CHECKSUM_UNNECESSARY;
979 continue;
980 }
981 merge = false;
982 }
983
984 copy = min_t(int, msg_data_left(msg),
985 pfrag->size - pfrag->offset);
986
987 if (!sk_wmem_schedule(sk, copy))
988 goto wait_for_memory;
989
990 err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
991 pfrag->page,
992 pfrag->offset,
993 copy);
994 if (err)
995 goto out_error;
996
997 /* Update the skb. */
998 if (merge) {
999 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1000 } else {
1001 skb_fill_page_desc(skb, i, pfrag->page,
1002 pfrag->offset, copy);
1003 get_page(pfrag->page);
1004 }
1005
1006 pfrag->offset += copy;
1007 copied += copy;
1008 if (head != skb) {
1009 head->len += copy;
1010 head->data_len += copy;
1011 }
1012
1013 continue;
1014
1015 wait_for_memory:
1016 kcm_push(kcm);
1017 err = sk_stream_wait_memory(sk, &timeo);
1018 if (err)
1019 goto out_error;
1020 }
1021
1022 if (eor) {
1023 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
1024
1025 if (head) {
1026 /* Message complete, queue it on send buffer */
1027 __skb_queue_tail(&sk->sk_write_queue, head);
1028 kcm->seq_skb = NULL;
1029 KCM_STATS_INCR(kcm->stats.tx_msgs);
1030 }
1031
1032 if (msg->msg_flags & MSG_BATCH) {
1033 kcm->tx_wait_more = true;
1034 } else if (kcm->tx_wait_more || not_busy) {
1035 err = kcm_write_msgs(kcm);
1036 if (err < 0) {
1037 /* We got a hard error in write_msgs but have
1038 * already queued this message. Report an error
1039 * in the socket, but don't affect return value
1040 * from sendmsg
1041 */
1042 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
1043 report_csk_error(&kcm->sk, -err);
1044 }
1045 }
1046 } else {
1047 /* Message not complete, save state */
1048 partial_message:
1049 if (head) {
1050 kcm->seq_skb = head;
1051 kcm_tx_msg(head)->last_skb = skb;
1052 }
1053 }
1054
1055 KCM_STATS_ADD(kcm->stats.tx_bytes, copied);
1056
1057 release_sock(sk);
1058 return copied;
1059
1060 out_error:
1061 kcm_push(kcm);
1062
1063 if (copied && sock->type == SOCK_SEQPACKET) {
1064 /* Wrote some bytes before encountering an
1065 * error, return partial success.
1066 */
1067 goto partial_message;
1068 }
1069
1070 if (head != kcm->seq_skb)
1071 kfree_skb(head);
1072
1073 err = sk_stream_error(sk, msg->msg_flags, err);
1074
1075 /* make sure we wake any epoll edge trigger waiter */
1076 if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
1077 sk->sk_write_space(sk);
1078
1079 release_sock(sk);
1080 return err;
1081 }
1082
1083 static struct sk_buff *kcm_wait_data(struct sock *sk, int flags,
1084 long timeo, int *err)
1085 {
1086 struct sk_buff *skb;
1087
1088 while (!(skb = skb_peek(&sk->sk_receive_queue))) {
1089 if (sk->sk_err) {
1090 *err = sock_error(sk);
1091 return NULL;
1092 }
1093
1094 if (sock_flag(sk, SOCK_DONE))
1095 return NULL;
1096
1097 if ((flags & MSG_DONTWAIT) || !timeo) {
1098 *err = -EAGAIN;
1099 return NULL;
1100 }
1101
1102 sk_wait_data(sk, &timeo, NULL);
1103
1104 /* Handle signals */
1105 if (signal_pending(current)) {
1106 *err = sock_intr_errno(timeo);
1107 return NULL;
1108 }
1109 }
1110
1111 return skb;
1112 }
1113
1114 static int kcm_recvmsg(struct socket *sock, struct msghdr *msg,
1115 size_t len, int flags)
1116 {
1117 struct sock *sk = sock->sk;
1118 struct kcm_sock *kcm = kcm_sk(sk);
1119 int err = 0;
1120 long timeo;
1121 struct strp_msg *stm;
1122 int copied = 0;
1123 struct sk_buff *skb;
1124
1125 timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
1126
1127 lock_sock(sk);
1128
1129 skb = kcm_wait_data(sk, flags, timeo, &err);
1130 if (!skb)
1131 goto out;
1132
1133 /* Okay, have a message on the receive queue */
1134
1135 stm = strp_msg(skb);
1136
1137 if (len > stm->full_len)
1138 len = stm->full_len;
1139
1140 err = skb_copy_datagram_msg(skb, stm->offset, msg, len);
1141 if (err < 0)
1142 goto out;
1143
1144 copied = len;
1145 if (likely(!(flags & MSG_PEEK))) {
1146 KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1147 if (copied < stm->full_len) {
1148 if (sock->type == SOCK_DGRAM) {
1149 /* Truncated message */
1150 msg->msg_flags |= MSG_TRUNC;
1151 goto msg_finished;
1152 }
1153 stm->offset += copied;
1154 stm->full_len -= copied;
1155 } else {
1156 msg_finished:
1157 /* Finished with message */
1158 msg->msg_flags |= MSG_EOR;
1159 KCM_STATS_INCR(kcm->stats.rx_msgs);
1160 skb_unlink(skb, &sk->sk_receive_queue);
1161 kfree_skb(skb);
1162 }
1163 }
1164
1165 out:
1166 release_sock(sk);
1167
1168 return copied ? : err;
1169 }
1170
1171 static ssize_t kcm_splice_read(struct socket *sock, loff_t *ppos,
1172 struct pipe_inode_info *pipe, size_t len,
1173 unsigned int flags)
1174 {
1175 struct sock *sk = sock->sk;
1176 struct kcm_sock *kcm = kcm_sk(sk);
1177 long timeo;
1178 struct strp_msg *stm;
1179 int err = 0;
1180 ssize_t copied;
1181 struct sk_buff *skb;
1182
1183 /* Only support splice for SOCKSEQPACKET */
1184
1185 timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
1186
1187 lock_sock(sk);
1188
1189 skb = kcm_wait_data(sk, flags, timeo, &err);
1190 if (!skb)
1191 goto err_out;
1192
1193 /* Okay, have a message on the receive queue */
1194
1195 stm = strp_msg(skb);
1196
1197 if (len > stm->full_len)
1198 len = stm->full_len;
1199
1200 copied = skb_splice_bits(skb, sk, stm->offset, pipe, len, flags);
1201 if (copied < 0) {
1202 err = copied;
1203 goto err_out;
1204 }
1205
1206 KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1207
1208 stm->offset += copied;
1209 stm->full_len -= copied;
1210
1211 /* We have no way to return MSG_EOR. If all the bytes have been
1212 * read we still leave the message in the receive socket buffer.
1213 * A subsequent recvmsg needs to be done to return MSG_EOR and
1214 * finish reading the message.
1215 */
1216
1217 release_sock(sk);
1218
1219 return copied;
1220
1221 err_out:
1222 release_sock(sk);
1223
1224 return err;
1225 }
1226
1227 /* kcm sock lock held */
1228 static void kcm_recv_disable(struct kcm_sock *kcm)
1229 {
1230 struct kcm_mux *mux = kcm->mux;
1231
1232 if (kcm->rx_disabled)
1233 return;
1234
1235 spin_lock_bh(&mux->rx_lock);
1236
1237 kcm->rx_disabled = 1;
1238
1239 /* If a psock is reserved we'll do cleanup in unreserve */
1240 if (!kcm->rx_psock) {
1241 if (kcm->rx_wait) {
1242 list_del(&kcm->wait_rx_list);
1243 kcm->rx_wait = false;
1244 }
1245
1246 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
1247 }
1248
1249 spin_unlock_bh(&mux->rx_lock);
1250 }
1251
1252 /* kcm sock lock held */
1253 static void kcm_recv_enable(struct kcm_sock *kcm)
1254 {
1255 struct kcm_mux *mux = kcm->mux;
1256
1257 if (!kcm->rx_disabled)
1258 return;
1259
1260 spin_lock_bh(&mux->rx_lock);
1261
1262 kcm->rx_disabled = 0;
1263 kcm_rcv_ready(kcm);
1264
1265 spin_unlock_bh(&mux->rx_lock);
1266 }
1267
1268 static int kcm_setsockopt(struct socket *sock, int level, int optname,
1269 char __user *optval, unsigned int optlen)
1270 {
1271 struct kcm_sock *kcm = kcm_sk(sock->sk);
1272 int val, valbool;
1273 int err = 0;
1274
1275 if (level != SOL_KCM)
1276 return -ENOPROTOOPT;
1277
1278 if (optlen < sizeof(int))
1279 return -EINVAL;
1280
1281 if (get_user(val, (int __user *)optval))
1282 return -EINVAL;
1283
1284 valbool = val ? 1 : 0;
1285
1286 switch (optname) {
1287 case KCM_RECV_DISABLE:
1288 lock_sock(&kcm->sk);
1289 if (valbool)
1290 kcm_recv_disable(kcm);
1291 else
1292 kcm_recv_enable(kcm);
1293 release_sock(&kcm->sk);
1294 break;
1295 default:
1296 err = -ENOPROTOOPT;
1297 }
1298
1299 return err;
1300 }
1301
1302 static int kcm_getsockopt(struct socket *sock, int level, int optname,
1303 char __user *optval, int __user *optlen)
1304 {
1305 struct kcm_sock *kcm = kcm_sk(sock->sk);
1306 int val, len;
1307
1308 if (level != SOL_KCM)
1309 return -ENOPROTOOPT;
1310
1311 if (get_user(len, optlen))
1312 return -EFAULT;
1313
1314 len = min_t(unsigned int, len, sizeof(int));
1315 if (len < 0)
1316 return -EINVAL;
1317
1318 switch (optname) {
1319 case KCM_RECV_DISABLE:
1320 val = kcm->rx_disabled;
1321 break;
1322 default:
1323 return -ENOPROTOOPT;
1324 }
1325
1326 if (put_user(len, optlen))
1327 return -EFAULT;
1328 if (copy_to_user(optval, &val, len))
1329 return -EFAULT;
1330 return 0;
1331 }
1332
1333 static void init_kcm_sock(struct kcm_sock *kcm, struct kcm_mux *mux)
1334 {
1335 struct kcm_sock *tkcm;
1336 struct list_head *head;
1337 int index = 0;
1338
1339 /* For SOCK_SEQPACKET sock type, datagram_poll checks the sk_state, so
1340 * we set sk_state, otherwise epoll_wait always returns right away with
1341 * EPOLLHUP
1342 */
1343 kcm->sk.sk_state = TCP_ESTABLISHED;
1344
1345 /* Add to mux's kcm sockets list */
1346 kcm->mux = mux;
1347 spin_lock_bh(&mux->lock);
1348
1349 head = &mux->kcm_socks;
1350 list_for_each_entry(tkcm, &mux->kcm_socks, kcm_sock_list) {
1351 if (tkcm->index != index)
1352 break;
1353 head = &tkcm->kcm_sock_list;
1354 index++;
1355 }
1356
1357 list_add(&kcm->kcm_sock_list, head);
1358 kcm->index = index;
1359
1360 mux->kcm_socks_cnt++;
1361 spin_unlock_bh(&mux->lock);
1362
1363 INIT_WORK(&kcm->tx_work, kcm_tx_work);
1364
1365 spin_lock_bh(&mux->rx_lock);
1366 kcm_rcv_ready(kcm);
1367 spin_unlock_bh(&mux->rx_lock);
1368 }
1369
1370 static int kcm_attach(struct socket *sock, struct socket *csock,
1371 struct bpf_prog *prog)
1372 {
1373 struct kcm_sock *kcm = kcm_sk(sock->sk);
1374 struct kcm_mux *mux = kcm->mux;
1375 struct sock *csk;
1376 struct kcm_psock *psock = NULL, *tpsock;
1377 struct list_head *head;
1378 int index = 0;
1379 static const struct strp_callbacks cb = {
1380 .rcv_msg = kcm_rcv_strparser,
1381 .parse_msg = kcm_parse_func_strparser,
1382 .read_sock_done = kcm_read_sock_done,
1383 };
1384 int err = 0;
1385
1386 csk = csock->sk;
1387 if (!csk)
1388 return -EINVAL;
1389
1390 lock_sock(csk);
1391
1392 /* Only allow TCP sockets to be attached for now */
1393 if ((csk->sk_family != AF_INET && csk->sk_family != AF_INET6) ||
1394 csk->sk_protocol != IPPROTO_TCP) {
1395 err = -EOPNOTSUPP;
1396 goto out;
1397 }
1398
1399 /* Don't allow listeners or closed sockets */
1400 if (csk->sk_state == TCP_LISTEN || csk->sk_state == TCP_CLOSE) {
1401 err = -EOPNOTSUPP;
1402 goto out;
1403 }
1404
1405 psock = kmem_cache_zalloc(kcm_psockp, GFP_KERNEL);
1406 if (!psock) {
1407 err = -ENOMEM;
1408 goto out;
1409 }
1410
1411 psock->mux = mux;
1412 psock->sk = csk;
1413 psock->bpf_prog = prog;
1414
1415 err = strp_init(&psock->strp, csk, &cb);
1416 if (err) {
1417 kmem_cache_free(kcm_psockp, psock);
1418 goto out;
1419 }
1420
1421 write_lock_bh(&csk->sk_callback_lock);
1422
1423 /* Check if sk_user_data is aready by KCM or someone else.
1424 * Must be done under lock to prevent race conditions.
1425 */
1426 if (csk->sk_user_data) {
1427 write_unlock_bh(&csk->sk_callback_lock);
1428 strp_stop(&psock->strp);
1429 strp_done(&psock->strp);
1430 kmem_cache_free(kcm_psockp, psock);
1431 err = -EALREADY;
1432 goto out;
1433 }
1434
1435 psock->save_data_ready = csk->sk_data_ready;
1436 psock->save_write_space = csk->sk_write_space;
1437 psock->save_state_change = csk->sk_state_change;
1438 csk->sk_user_data = psock;
1439 csk->sk_data_ready = psock_data_ready;
1440 csk->sk_write_space = psock_write_space;
1441 csk->sk_state_change = psock_state_change;
1442
1443 write_unlock_bh(&csk->sk_callback_lock);
1444
1445 sock_hold(csk);
1446
1447 /* Finished initialization, now add the psock to the MUX. */
1448 spin_lock_bh(&mux->lock);
1449 head = &mux->psocks;
1450 list_for_each_entry(tpsock, &mux->psocks, psock_list) {
1451 if (tpsock->index != index)
1452 break;
1453 head = &tpsock->psock_list;
1454 index++;
1455 }
1456
1457 list_add(&psock->psock_list, head);
1458 psock->index = index;
1459
1460 KCM_STATS_INCR(mux->stats.psock_attach);
1461 mux->psocks_cnt++;
1462 psock_now_avail(psock);
1463 spin_unlock_bh(&mux->lock);
1464
1465 /* Schedule RX work in case there are already bytes queued */
1466 strp_check_rcv(&psock->strp);
1467
1468 out:
1469 release_sock(csk);
1470
1471 return err;
1472 }
1473
1474 static int kcm_attach_ioctl(struct socket *sock, struct kcm_attach *info)
1475 {
1476 struct socket *csock;
1477 struct bpf_prog *prog;
1478 int err;
1479
1480 csock = sockfd_lookup(info->fd, &err);
1481 if (!csock)
1482 return -ENOENT;
1483
1484 prog = bpf_prog_get_type(info->bpf_fd, BPF_PROG_TYPE_SOCKET_FILTER);
1485 if (IS_ERR(prog)) {
1486 err = PTR_ERR(prog);
1487 goto out;
1488 }
1489
1490 err = kcm_attach(sock, csock, prog);
1491 if (err) {
1492 bpf_prog_put(prog);
1493 goto out;
1494 }
1495
1496 /* Keep reference on file also */
1497
1498 return 0;
1499 out:
1500 fput(csock->file);
1501 return err;
1502 }
1503
1504 static void kcm_unattach(struct kcm_psock *psock)
1505 {
1506 struct sock *csk = psock->sk;
1507 struct kcm_mux *mux = psock->mux;
1508
1509 lock_sock(csk);
1510
1511 /* Stop getting callbacks from TCP socket. After this there should
1512 * be no way to reserve a kcm for this psock.
1513 */
1514 write_lock_bh(&csk->sk_callback_lock);
1515 csk->sk_user_data = NULL;
1516 csk->sk_data_ready = psock->save_data_ready;
1517 csk->sk_write_space = psock->save_write_space;
1518 csk->sk_state_change = psock->save_state_change;
1519 strp_stop(&psock->strp);
1520
1521 if (WARN_ON(psock->rx_kcm)) {
1522 write_unlock_bh(&csk->sk_callback_lock);
1523 release_sock(csk);
1524 return;
1525 }
1526
1527 spin_lock_bh(&mux->rx_lock);
1528
1529 /* Stop receiver activities. After this point psock should not be
1530 * able to get onto ready list either through callbacks or work.
1531 */
1532 if (psock->ready_rx_msg) {
1533 list_del(&psock->psock_ready_list);
1534 kfree_skb(psock->ready_rx_msg);
1535 psock->ready_rx_msg = NULL;
1536 KCM_STATS_INCR(mux->stats.rx_ready_drops);
1537 }
1538
1539 spin_unlock_bh(&mux->rx_lock);
1540
1541 write_unlock_bh(&csk->sk_callback_lock);
1542
1543 /* Call strp_done without sock lock */
1544 release_sock(csk);
1545 strp_done(&psock->strp);
1546 lock_sock(csk);
1547
1548 bpf_prog_put(psock->bpf_prog);
1549
1550 spin_lock_bh(&mux->lock);
1551
1552 aggregate_psock_stats(&psock->stats, &mux->aggregate_psock_stats);
1553 save_strp_stats(&psock->strp, &mux->aggregate_strp_stats);
1554
1555 KCM_STATS_INCR(mux->stats.psock_unattach);
1556
1557 if (psock->tx_kcm) {
1558 /* psock was reserved. Just mark it finished and we will clean
1559 * up in the kcm paths, we need kcm lock which can not be
1560 * acquired here.
1561 */
1562 KCM_STATS_INCR(mux->stats.psock_unattach_rsvd);
1563 spin_unlock_bh(&mux->lock);
1564
1565 /* We are unattaching a socket that is reserved. Abort the
1566 * socket since we may be out of sync in sending on it. We need
1567 * to do this without the mux lock.
1568 */
1569 kcm_abort_tx_psock(psock, EPIPE, false);
1570
1571 spin_lock_bh(&mux->lock);
1572 if (!psock->tx_kcm) {
1573 /* psock now unreserved in window mux was unlocked */
1574 goto no_reserved;
1575 }
1576 psock->done = 1;
1577
1578 /* Commit done before queuing work to process it */
1579 smp_mb();
1580
1581 /* Queue tx work to make sure psock->done is handled */
1582 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
1583 spin_unlock_bh(&mux->lock);
1584 } else {
1585 no_reserved:
1586 if (!psock->tx_stopped)
1587 list_del(&psock->psock_avail_list);
1588 list_del(&psock->psock_list);
1589 mux->psocks_cnt--;
1590 spin_unlock_bh(&mux->lock);
1591
1592 sock_put(csk);
1593 fput(csk->sk_socket->file);
1594 kmem_cache_free(kcm_psockp, psock);
1595 }
1596
1597 release_sock(csk);
1598 }
1599
1600 static int kcm_unattach_ioctl(struct socket *sock, struct kcm_unattach *info)
1601 {
1602 struct kcm_sock *kcm = kcm_sk(sock->sk);
1603 struct kcm_mux *mux = kcm->mux;
1604 struct kcm_psock *psock;
1605 struct socket *csock;
1606 struct sock *csk;
1607 int err;
1608
1609 csock = sockfd_lookup(info->fd, &err);
1610 if (!csock)
1611 return -ENOENT;
1612
1613 csk = csock->sk;
1614 if (!csk) {
1615 err = -EINVAL;
1616 goto out;
1617 }
1618
1619 err = -ENOENT;
1620
1621 spin_lock_bh(&mux->lock);
1622
1623 list_for_each_entry(psock, &mux->psocks, psock_list) {
1624 if (psock->sk != csk)
1625 continue;
1626
1627 /* Found the matching psock */
1628
1629 if (psock->unattaching || WARN_ON(psock->done)) {
1630 err = -EALREADY;
1631 break;
1632 }
1633
1634 psock->unattaching = 1;
1635
1636 spin_unlock_bh(&mux->lock);
1637
1638 /* Lower socket lock should already be held */
1639 kcm_unattach(psock);
1640
1641 err = 0;
1642 goto out;
1643 }
1644
1645 spin_unlock_bh(&mux->lock);
1646
1647 out:
1648 fput(csock->file);
1649 return err;
1650 }
1651
1652 static struct proto kcm_proto = {
1653 .name = "KCM",
1654 .owner = THIS_MODULE,
1655 .obj_size = sizeof(struct kcm_sock),
1656 };
1657
1658 /* Clone a kcm socket. */
1659 static struct file *kcm_clone(struct socket *osock)
1660 {
1661 struct socket *newsock;
1662 struct sock *newsk;
1663
1664 newsock = sock_alloc();
1665 if (!newsock)
1666 return ERR_PTR(-ENFILE);
1667
1668 newsock->type = osock->type;
1669 newsock->ops = osock->ops;
1670
1671 __module_get(newsock->ops->owner);
1672
1673 newsk = sk_alloc(sock_net(osock->sk), PF_KCM, GFP_KERNEL,
1674 &kcm_proto, false);
1675 if (!newsk) {
1676 sock_release(newsock);
1677 return ERR_PTR(-ENOMEM);
1678 }
1679 sock_init_data(newsock, newsk);
1680 init_kcm_sock(kcm_sk(newsk), kcm_sk(osock->sk)->mux);
1681
1682 return sock_alloc_file(newsock, 0, osock->sk->sk_prot_creator->name);
1683 }
1684
1685 static int kcm_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
1686 {
1687 int err;
1688
1689 switch (cmd) {
1690 case SIOCKCMATTACH: {
1691 struct kcm_attach info;
1692
1693 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1694 return -EFAULT;
1695
1696 err = kcm_attach_ioctl(sock, &info);
1697
1698 break;
1699 }
1700 case SIOCKCMUNATTACH: {
1701 struct kcm_unattach info;
1702
1703 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1704 return -EFAULT;
1705
1706 err = kcm_unattach_ioctl(sock, &info);
1707
1708 break;
1709 }
1710 case SIOCKCMCLONE: {
1711 struct kcm_clone info;
1712 struct file *file;
1713
1714 info.fd = get_unused_fd_flags(0);
1715 if (unlikely(info.fd < 0))
1716 return info.fd;
1717
1718 file = kcm_clone(sock);
1719 if (IS_ERR(file)) {
1720 put_unused_fd(info.fd);
1721 return PTR_ERR(file);
1722 }
1723 if (copy_to_user((void __user *)arg, &info,
1724 sizeof(info))) {
1725 put_unused_fd(info.fd);
1726 fput(file);
1727 return -EFAULT;
1728 }
1729 fd_install(info.fd, file);
1730 err = 0;
1731 break;
1732 }
1733 default:
1734 err = -ENOIOCTLCMD;
1735 break;
1736 }
1737
1738 return err;
1739 }
1740
1741 static void free_mux(struct rcu_head *rcu)
1742 {
1743 struct kcm_mux *mux = container_of(rcu,
1744 struct kcm_mux, rcu);
1745
1746 kmem_cache_free(kcm_muxp, mux);
1747 }
1748
1749 static void release_mux(struct kcm_mux *mux)
1750 {
1751 struct kcm_net *knet = mux->knet;
1752 struct kcm_psock *psock, *tmp_psock;
1753
1754 /* Release psocks */
1755 list_for_each_entry_safe(psock, tmp_psock,
1756 &mux->psocks, psock_list) {
1757 if (!WARN_ON(psock->unattaching))
1758 kcm_unattach(psock);
1759 }
1760
1761 if (WARN_ON(mux->psocks_cnt))
1762 return;
1763
1764 __skb_queue_purge(&mux->rx_hold_queue);
1765
1766 mutex_lock(&knet->mutex);
1767 aggregate_mux_stats(&mux->stats, &knet->aggregate_mux_stats);
1768 aggregate_psock_stats(&mux->aggregate_psock_stats,
1769 &knet->aggregate_psock_stats);
1770 aggregate_strp_stats(&mux->aggregate_strp_stats,
1771 &knet->aggregate_strp_stats);
1772 list_del_rcu(&mux->kcm_mux_list);
1773 knet->count--;
1774 mutex_unlock(&knet->mutex);
1775
1776 call_rcu(&mux->rcu, free_mux);
1777 }
1778
1779 static void kcm_done(struct kcm_sock *kcm)
1780 {
1781 struct kcm_mux *mux = kcm->mux;
1782 struct sock *sk = &kcm->sk;
1783 int socks_cnt;
1784
1785 spin_lock_bh(&mux->rx_lock);
1786 if (kcm->rx_psock) {
1787 /* Cleanup in unreserve_rx_kcm */
1788 WARN_ON(kcm->done);
1789 kcm->rx_disabled = 1;
1790 kcm->done = 1;
1791 spin_unlock_bh(&mux->rx_lock);
1792 return;
1793 }
1794
1795 if (kcm->rx_wait) {
1796 list_del(&kcm->wait_rx_list);
1797 kcm->rx_wait = false;
1798 }
1799 /* Move any pending receive messages to other kcm sockets */
1800 requeue_rx_msgs(mux, &sk->sk_receive_queue);
1801
1802 spin_unlock_bh(&mux->rx_lock);
1803
1804 if (WARN_ON(sk_rmem_alloc_get(sk)))
1805 return;
1806
1807 /* Detach from MUX */
1808 spin_lock_bh(&mux->lock);
1809
1810 list_del(&kcm->kcm_sock_list);
1811 mux->kcm_socks_cnt--;
1812 socks_cnt = mux->kcm_socks_cnt;
1813
1814 spin_unlock_bh(&mux->lock);
1815
1816 if (!socks_cnt) {
1817 /* We are done with the mux now. */
1818 release_mux(mux);
1819 }
1820
1821 WARN_ON(kcm->rx_wait);
1822
1823 sock_put(&kcm->sk);
1824 }
1825
1826 /* Called by kcm_release to close a KCM socket.
1827 * If this is the last KCM socket on the MUX, destroy the MUX.
1828 */
1829 static int kcm_release(struct socket *sock)
1830 {
1831 struct sock *sk = sock->sk;
1832 struct kcm_sock *kcm;
1833 struct kcm_mux *mux;
1834 struct kcm_psock *psock;
1835
1836 if (!sk)
1837 return 0;
1838
1839 kcm = kcm_sk(sk);
1840 mux = kcm->mux;
1841
1842 sock_orphan(sk);
1843 kfree_skb(kcm->seq_skb);
1844
1845 lock_sock(sk);
1846 /* Purge queue under lock to avoid race condition with tx_work trying
1847 * to act when queue is nonempty. If tx_work runs after this point
1848 * it will just return.
1849 */
1850 __skb_queue_purge(&sk->sk_write_queue);
1851
1852 /* Set tx_stopped. This is checked when psock is bound to a kcm and we
1853 * get a writespace callback. This prevents further work being queued
1854 * from the callback (unbinding the psock occurs after canceling work.
1855 */
1856 kcm->tx_stopped = 1;
1857
1858 release_sock(sk);
1859
1860 spin_lock_bh(&mux->lock);
1861 if (kcm->tx_wait) {
1862 /* Take of tx_wait list, after this point there should be no way
1863 * that a psock will be assigned to this kcm.
1864 */
1865 list_del(&kcm->wait_psock_list);
1866 kcm->tx_wait = false;
1867 }
1868 spin_unlock_bh(&mux->lock);
1869
1870 /* Cancel work. After this point there should be no outside references
1871 * to the kcm socket.
1872 */
1873 cancel_work_sync(&kcm->tx_work);
1874
1875 lock_sock(sk);
1876 psock = kcm->tx_psock;
1877 if (psock) {
1878 /* A psock was reserved, so we need to kill it since it
1879 * may already have some bytes queued from a message. We
1880 * need to do this after removing kcm from tx_wait list.
1881 */
1882 kcm_abort_tx_psock(psock, EPIPE, false);
1883 unreserve_psock(kcm);
1884 }
1885 release_sock(sk);
1886
1887 WARN_ON(kcm->tx_wait);
1888 WARN_ON(kcm->tx_psock);
1889
1890 sock->sk = NULL;
1891
1892 kcm_done(kcm);
1893
1894 return 0;
1895 }
1896
1897 static const struct proto_ops kcm_dgram_ops = {
1898 .family = PF_KCM,
1899 .owner = THIS_MODULE,
1900 .release = kcm_release,
1901 .bind = sock_no_bind,
1902 .connect = sock_no_connect,
1903 .socketpair = sock_no_socketpair,
1904 .accept = sock_no_accept,
1905 .getname = sock_no_getname,
1906 .poll = datagram_poll,
1907 .ioctl = kcm_ioctl,
1908 .listen = sock_no_listen,
1909 .shutdown = sock_no_shutdown,
1910 .setsockopt = kcm_setsockopt,
1911 .getsockopt = kcm_getsockopt,
1912 .sendmsg = kcm_sendmsg,
1913 .recvmsg = kcm_recvmsg,
1914 .mmap = sock_no_mmap,
1915 .sendpage = kcm_sendpage,
1916 };
1917
1918 static const struct proto_ops kcm_seqpacket_ops = {
1919 .family = PF_KCM,
1920 .owner = THIS_MODULE,
1921 .release = kcm_release,
1922 .bind = sock_no_bind,
1923 .connect = sock_no_connect,
1924 .socketpair = sock_no_socketpair,
1925 .accept = sock_no_accept,
1926 .getname = sock_no_getname,
1927 .poll = datagram_poll,
1928 .ioctl = kcm_ioctl,
1929 .listen = sock_no_listen,
1930 .shutdown = sock_no_shutdown,
1931 .setsockopt = kcm_setsockopt,
1932 .getsockopt = kcm_getsockopt,
1933 .sendmsg = kcm_sendmsg,
1934 .recvmsg = kcm_recvmsg,
1935 .mmap = sock_no_mmap,
1936 .sendpage = kcm_sendpage,
1937 .splice_read = kcm_splice_read,
1938 };
1939
1940 /* Create proto operation for kcm sockets */
1941 static int kcm_create(struct net *net, struct socket *sock,
1942 int protocol, int kern)
1943 {
1944 struct kcm_net *knet = net_generic(net, kcm_net_id);
1945 struct sock *sk;
1946 struct kcm_mux *mux;
1947
1948 switch (sock->type) {
1949 case SOCK_DGRAM:
1950 sock->ops = &kcm_dgram_ops;
1951 break;
1952 case SOCK_SEQPACKET:
1953 sock->ops = &kcm_seqpacket_ops;
1954 break;
1955 default:
1956 return -ESOCKTNOSUPPORT;
1957 }
1958
1959 if (protocol != KCMPROTO_CONNECTED)
1960 return -EPROTONOSUPPORT;
1961
1962 sk = sk_alloc(net, PF_KCM, GFP_KERNEL, &kcm_proto, kern);
1963 if (!sk)
1964 return -ENOMEM;
1965
1966 /* Allocate a kcm mux, shared between KCM sockets */
1967 mux = kmem_cache_zalloc(kcm_muxp, GFP_KERNEL);
1968 if (!mux) {
1969 sk_free(sk);
1970 return -ENOMEM;
1971 }
1972
1973 spin_lock_init(&mux->lock);
1974 spin_lock_init(&mux->rx_lock);
1975 INIT_LIST_HEAD(&mux->kcm_socks);
1976 INIT_LIST_HEAD(&mux->kcm_rx_waiters);
1977 INIT_LIST_HEAD(&mux->kcm_tx_waiters);
1978
1979 INIT_LIST_HEAD(&mux->psocks);
1980 INIT_LIST_HEAD(&mux->psocks_ready);
1981 INIT_LIST_HEAD(&mux->psocks_avail);
1982
1983 mux->knet = knet;
1984
1985 /* Add new MUX to list */
1986 mutex_lock(&knet->mutex);
1987 list_add_rcu(&mux->kcm_mux_list, &knet->mux_list);
1988 knet->count++;
1989 mutex_unlock(&knet->mutex);
1990
1991 skb_queue_head_init(&mux->rx_hold_queue);
1992
1993 /* Init KCM socket */
1994 sock_init_data(sock, sk);
1995 init_kcm_sock(kcm_sk(sk), mux);
1996
1997 return 0;
1998 }
1999
2000 static const struct net_proto_family kcm_family_ops = {
2001 .family = PF_KCM,
2002 .create = kcm_create,
2003 .owner = THIS_MODULE,
2004 };
2005
2006 static __net_init int kcm_init_net(struct net *net)
2007 {
2008 struct kcm_net *knet = net_generic(net, kcm_net_id);
2009
2010 INIT_LIST_HEAD_RCU(&knet->mux_list);
2011 mutex_init(&knet->mutex);
2012
2013 return 0;
2014 }
2015
2016 static __net_exit void kcm_exit_net(struct net *net)
2017 {
2018 struct kcm_net *knet = net_generic(net, kcm_net_id);
2019
2020 /* All KCM sockets should be closed at this point, which should mean
2021 * that all multiplexors and psocks have been destroyed.
2022 */
2023 WARN_ON(!list_empty(&knet->mux_list));
2024 }
2025
2026 static struct pernet_operations kcm_net_ops = {
2027 .init = kcm_init_net,
2028 .exit = kcm_exit_net,
2029 .id = &kcm_net_id,
2030 .size = sizeof(struct kcm_net),
2031 };
2032
2033 static int __init kcm_init(void)
2034 {
2035 int err = -ENOMEM;
2036
2037 kcm_muxp = kmem_cache_create("kcm_mux_cache",
2038 sizeof(struct kcm_mux), 0,
2039 SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
2040 if (!kcm_muxp)
2041 goto fail;
2042
2043 kcm_psockp = kmem_cache_create("kcm_psock_cache",
2044 sizeof(struct kcm_psock), 0,
2045 SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
2046 if (!kcm_psockp)
2047 goto fail;
2048
2049 kcm_wq = create_singlethread_workqueue("kkcmd");
2050 if (!kcm_wq)
2051 goto fail;
2052
2053 err = proto_register(&kcm_proto, 1);
2054 if (err)
2055 goto fail;
2056
2057 err = sock_register(&kcm_family_ops);
2058 if (err)
2059 goto sock_register_fail;
2060
2061 err = register_pernet_device(&kcm_net_ops);
2062 if (err)
2063 goto net_ops_fail;
2064
2065 err = kcm_proc_init();
2066 if (err)
2067 goto proc_init_fail;
2068
2069 return 0;
2070
2071 proc_init_fail:
2072 unregister_pernet_device(&kcm_net_ops);
2073
2074 net_ops_fail:
2075 sock_unregister(PF_KCM);
2076
2077 sock_register_fail:
2078 proto_unregister(&kcm_proto);
2079
2080 fail:
2081 kmem_cache_destroy(kcm_muxp);
2082 kmem_cache_destroy(kcm_psockp);
2083
2084 if (kcm_wq)
2085 destroy_workqueue(kcm_wq);
2086
2087 return err;
2088 }
2089
2090 static void __exit kcm_exit(void)
2091 {
2092 kcm_proc_exit();
2093 unregister_pernet_device(&kcm_net_ops);
2094 sock_unregister(PF_KCM);
2095 proto_unregister(&kcm_proto);
2096 destroy_workqueue(kcm_wq);
2097
2098 kmem_cache_destroy(kcm_muxp);
2099 kmem_cache_destroy(kcm_psockp);
2100 }
2101
2102 module_init(kcm_init);
2103 module_exit(kcm_exit);
2104
2105 MODULE_LICENSE("GPL");
2106 MODULE_ALIAS_NETPROTO(PF_KCM);
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