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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Kernel Connection Multiplexor
4 *
5 * Copyright (c) 2016 Tom Herbert <tom@herbertland.com>
6 */
7
8#include <linux/bpf.h>
9#include <linux/errno.h>
10#include <linux/errqueue.h>
11#include <linux/file.h>
12#include <linux/in.h>
13#include <linux/kernel.h>
14#include <linux/module.h>
15#include <linux/net.h>
16#include <linux/netdevice.h>
17#include <linux/poll.h>
18#include <linux/rculist.h>
19#include <linux/skbuff.h>
20#include <linux/socket.h>
21#include <linux/uaccess.h>
22#include <linux/workqueue.h>
23#include <linux/syscalls.h>
24#include <linux/sched/signal.h>
25
26#include <net/kcm.h>
27#include <net/netns/generic.h>
28#include <net/sock.h>
29#include <uapi/linux/kcm.h>
30
31unsigned int kcm_net_id;
32
33static struct kmem_cache *kcm_psockp __read_mostly;
34static struct kmem_cache *kcm_muxp __read_mostly;
35static struct workqueue_struct *kcm_wq;
36
37static inline struct kcm_sock *kcm_sk(const struct sock *sk)
38{
39 return (struct kcm_sock *)sk;
40}
41
42static inline struct kcm_tx_msg *kcm_tx_msg(struct sk_buff *skb)
43{
44 return (struct kcm_tx_msg *)skb->cb;
45}
46
47static void report_csk_error(struct sock *csk, int err)
48{
49 csk->sk_err = EPIPE;
50 csk->sk_error_report(csk);
51}
52
53static void kcm_abort_tx_psock(struct kcm_psock *psock, int err,
54 bool wakeup_kcm)
55{
56 struct sock *csk = psock->sk;
57 struct kcm_mux *mux = psock->mux;
58
59 /* Unrecoverable error in transmit */
60
61 spin_lock_bh(&mux->lock);
62
63 if (psock->tx_stopped) {
64 spin_unlock_bh(&mux->lock);
65 return;
66 }
67
68 psock->tx_stopped = 1;
69 KCM_STATS_INCR(psock->stats.tx_aborts);
70
71 if (!psock->tx_kcm) {
72 /* Take off psocks_avail list */
73 list_del(&psock->psock_avail_list);
74 } else if (wakeup_kcm) {
75 /* In this case psock is being aborted while outside of
76 * write_msgs and psock is reserved. Schedule tx_work
77 * to handle the failure there. Need to commit tx_stopped
78 * before queuing work.
79 */
80 smp_mb();
81
82 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
83 }
84
85 spin_unlock_bh(&mux->lock);
86
87 /* Report error on lower socket */
88 report_csk_error(csk, err);
89}
90
91/* RX mux lock held. */
92static void kcm_update_rx_mux_stats(struct kcm_mux *mux,
93 struct kcm_psock *psock)
94{
95 STRP_STATS_ADD(mux->stats.rx_bytes,
96 psock->strp.stats.bytes -
97 psock->saved_rx_bytes);
98 mux->stats.rx_msgs +=
99 psock->strp.stats.msgs - psock->saved_rx_msgs;
100 psock->saved_rx_msgs = psock->strp.stats.msgs;
101 psock->saved_rx_bytes = psock->strp.stats.bytes;
102}
103
104static void kcm_update_tx_mux_stats(struct kcm_mux *mux,
105 struct kcm_psock *psock)
106{
107 KCM_STATS_ADD(mux->stats.tx_bytes,
108 psock->stats.tx_bytes - psock->saved_tx_bytes);
109 mux->stats.tx_msgs +=
110 psock->stats.tx_msgs - psock->saved_tx_msgs;
111 psock->saved_tx_msgs = psock->stats.tx_msgs;
112 psock->saved_tx_bytes = psock->stats.tx_bytes;
113}
114
115static int kcm_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
116
117/* KCM is ready to receive messages on its queue-- either the KCM is new or
118 * has become unblocked after being blocked on full socket buffer. Queue any
119 * pending ready messages on a psock. RX mux lock held.
120 */
121static void kcm_rcv_ready(struct kcm_sock *kcm)
122{
123 struct kcm_mux *mux = kcm->mux;
124 struct kcm_psock *psock;
125 struct sk_buff *skb;
126
127 if (unlikely(kcm->rx_wait || kcm->rx_psock || kcm->rx_disabled))
128 return;
129
130 while (unlikely((skb = __skb_dequeue(&mux->rx_hold_queue)))) {
131 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
132 /* Assuming buffer limit has been reached */
133 skb_queue_head(&mux->rx_hold_queue, skb);
134 WARN_ON(!sk_rmem_alloc_get(&kcm->sk));
135 return;
136 }
137 }
138
139 while (!list_empty(&mux->psocks_ready)) {
140 psock = list_first_entry(&mux->psocks_ready, struct kcm_psock,
141 psock_ready_list);
142
143 if (kcm_queue_rcv_skb(&kcm->sk, psock->ready_rx_msg)) {
144 /* Assuming buffer limit has been reached */
145 WARN_ON(!sk_rmem_alloc_get(&kcm->sk));
146 return;
147 }
148
149 /* Consumed the ready message on the psock. Schedule rx_work to
150 * get more messages.
151 */
152 list_del(&psock->psock_ready_list);
153 psock->ready_rx_msg = NULL;
154 /* Commit clearing of ready_rx_msg for queuing work */
155 smp_mb();
156
157 strp_unpause(&psock->strp);
158 strp_check_rcv(&psock->strp);
159 }
160
161 /* Buffer limit is okay now, add to ready list */
162 list_add_tail(&kcm->wait_rx_list,
163 &kcm->mux->kcm_rx_waiters);
164 kcm->rx_wait = true;
165}
166
167static void kcm_rfree(struct sk_buff *skb)
168{
169 struct sock *sk = skb->sk;
170 struct kcm_sock *kcm = kcm_sk(sk);
171 struct kcm_mux *mux = kcm->mux;
172 unsigned int len = skb->truesize;
173
174 sk_mem_uncharge(sk, len);
175 atomic_sub(len, &sk->sk_rmem_alloc);
176
177 /* For reading rx_wait and rx_psock without holding lock */
178 smp_mb__after_atomic();
179
180 if (!kcm->rx_wait && !kcm->rx_psock &&
181 sk_rmem_alloc_get(sk) < sk->sk_rcvlowat) {
182 spin_lock_bh(&mux->rx_lock);
183 kcm_rcv_ready(kcm);
184 spin_unlock_bh(&mux->rx_lock);
185 }
186}
187
188static int kcm_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
189{
190 struct sk_buff_head *list = &sk->sk_receive_queue;
191
192 if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
193 return -ENOMEM;
194
195 if (!sk_rmem_schedule(sk, skb, skb->truesize))
196 return -ENOBUFS;
197
198 skb->dev = NULL;
199
200 skb_orphan(skb);
201 skb->sk = sk;
202 skb->destructor = kcm_rfree;
203 atomic_add(skb->truesize, &sk->sk_rmem_alloc);
204 sk_mem_charge(sk, skb->truesize);
205
206 skb_queue_tail(list, skb);
207
208 if (!sock_flag(sk, SOCK_DEAD))
209 sk->sk_data_ready(sk);
210
211 return 0;
212}
213
214/* Requeue received messages for a kcm socket to other kcm sockets. This is
215 * called with a kcm socket is receive disabled.
216 * RX mux lock held.
217 */
218static void requeue_rx_msgs(struct kcm_mux *mux, struct sk_buff_head *head)
219{
220 struct sk_buff *skb;
221 struct kcm_sock *kcm;
222
223 while ((skb = __skb_dequeue(head))) {
224 /* Reset destructor to avoid calling kcm_rcv_ready */
225 skb->destructor = sock_rfree;
226 skb_orphan(skb);
227try_again:
228 if (list_empty(&mux->kcm_rx_waiters)) {
229 skb_queue_tail(&mux->rx_hold_queue, skb);
230 continue;
231 }
232
233 kcm = list_first_entry(&mux->kcm_rx_waiters,
234 struct kcm_sock, wait_rx_list);
235
236 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
237 /* Should mean socket buffer full */
238 list_del(&kcm->wait_rx_list);
239 kcm->rx_wait = false;
240
241 /* Commit rx_wait to read in kcm_free */
242 smp_wmb();
243
244 goto try_again;
245 }
246 }
247}
248
249/* Lower sock lock held */
250static struct kcm_sock *reserve_rx_kcm(struct kcm_psock *psock,
251 struct sk_buff *head)
252{
253 struct kcm_mux *mux = psock->mux;
254 struct kcm_sock *kcm;
255
256 WARN_ON(psock->ready_rx_msg);
257
258 if (psock->rx_kcm)
259 return psock->rx_kcm;
260
261 spin_lock_bh(&mux->rx_lock);
262
263 if (psock->rx_kcm) {
264 spin_unlock_bh(&mux->rx_lock);
265 return psock->rx_kcm;
266 }
267
268 kcm_update_rx_mux_stats(mux, psock);
269
270 if (list_empty(&mux->kcm_rx_waiters)) {
271 psock->ready_rx_msg = head;
272 strp_pause(&psock->strp);
273 list_add_tail(&psock->psock_ready_list,
274 &mux->psocks_ready);
275 spin_unlock_bh(&mux->rx_lock);
276 return NULL;
277 }
278
279 kcm = list_first_entry(&mux->kcm_rx_waiters,
280 struct kcm_sock, wait_rx_list);
281 list_del(&kcm->wait_rx_list);
282 kcm->rx_wait = false;
283
284 psock->rx_kcm = kcm;
285 kcm->rx_psock = psock;
286
287 spin_unlock_bh(&mux->rx_lock);
288
289 return kcm;
290}
291
292static void kcm_done(struct kcm_sock *kcm);
293
294static void kcm_done_work(struct work_struct *w)
295{
296 kcm_done(container_of(w, struct kcm_sock, done_work));
297}
298
299/* Lower sock held */
300static void unreserve_rx_kcm(struct kcm_psock *psock,
301 bool rcv_ready)
302{
303 struct kcm_sock *kcm = psock->rx_kcm;
304 struct kcm_mux *mux = psock->mux;
305
306 if (!kcm)
307 return;
308
309 spin_lock_bh(&mux->rx_lock);
310
311 psock->rx_kcm = NULL;
312 kcm->rx_psock = NULL;
313
314 /* Commit kcm->rx_psock before sk_rmem_alloc_get to sync with
315 * kcm_rfree
316 */
317 smp_mb();
318
319 if (unlikely(kcm->done)) {
320 spin_unlock_bh(&mux->rx_lock);
321
322 /* Need to run kcm_done in a task since we need to qcquire
323 * callback locks which may already be held here.
324 */
325 INIT_WORK(&kcm->done_work, kcm_done_work);
326 schedule_work(&kcm->done_work);
327 return;
328 }
329
330 if (unlikely(kcm->rx_disabled)) {
331 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
332 } else if (rcv_ready || unlikely(!sk_rmem_alloc_get(&kcm->sk))) {
333 /* Check for degenerative race with rx_wait that all
334 * data was dequeued (accounted for in kcm_rfree).
335 */
336 kcm_rcv_ready(kcm);
337 }
338 spin_unlock_bh(&mux->rx_lock);
339}
340
341/* Lower sock lock held */
342static void psock_data_ready(struct sock *sk)
343{
344 struct kcm_psock *psock;
345
346 read_lock_bh(&sk->sk_callback_lock);
347
348 psock = (struct kcm_psock *)sk->sk_user_data;
349 if (likely(psock))
350 strp_data_ready(&psock->strp);
351
352 read_unlock_bh(&sk->sk_callback_lock);
353}
354
355/* Called with lower sock held */
356static void kcm_rcv_strparser(struct strparser *strp, struct sk_buff *skb)
357{
358 struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
359 struct kcm_sock *kcm;
360
361try_queue:
362 kcm = reserve_rx_kcm(psock, skb);
363 if (!kcm) {
364 /* Unable to reserve a KCM, message is held in psock and strp
365 * is paused.
366 */
367 return;
368 }
369
370 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
371 /* Should mean socket buffer full */
372 unreserve_rx_kcm(psock, false);
373 goto try_queue;
374 }
375}
376
377static int kcm_parse_func_strparser(struct strparser *strp, struct sk_buff *skb)
378{
379 struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
380 struct bpf_prog *prog = psock->bpf_prog;
381 int res;
382
383 res = bpf_prog_run_pin_on_cpu(prog, skb);
384 return res;
385}
386
387static int kcm_read_sock_done(struct strparser *strp, int err)
388{
389 struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
390
391 unreserve_rx_kcm(psock, true);
392
393 return err;
394}
395
396static void psock_state_change(struct sock *sk)
397{
398 /* TCP only does a EPOLLIN for a half close. Do a EPOLLHUP here
399 * since application will normally not poll with EPOLLIN
400 * on the TCP sockets.
401 */
402
403 report_csk_error(sk, EPIPE);
404}
405
406static void psock_write_space(struct sock *sk)
407{
408 struct kcm_psock *psock;
409 struct kcm_mux *mux;
410 struct kcm_sock *kcm;
411
412 read_lock_bh(&sk->sk_callback_lock);
413
414 psock = (struct kcm_psock *)sk->sk_user_data;
415 if (unlikely(!psock))
416 goto out;
417 mux = psock->mux;
418
419 spin_lock_bh(&mux->lock);
420
421 /* Check if the socket is reserved so someone is waiting for sending. */
422 kcm = psock->tx_kcm;
423 if (kcm && !unlikely(kcm->tx_stopped))
424 queue_work(kcm_wq, &kcm->tx_work);
425
426 spin_unlock_bh(&mux->lock);
427out:
428 read_unlock_bh(&sk->sk_callback_lock);
429}
430
431static void unreserve_psock(struct kcm_sock *kcm);
432
433/* kcm sock is locked. */
434static struct kcm_psock *reserve_psock(struct kcm_sock *kcm)
435{
436 struct kcm_mux *mux = kcm->mux;
437 struct kcm_psock *psock;
438
439 psock = kcm->tx_psock;
440
441 smp_rmb(); /* Must read tx_psock before tx_wait */
442
443 if (psock) {
444 WARN_ON(kcm->tx_wait);
445 if (unlikely(psock->tx_stopped))
446 unreserve_psock(kcm);
447 else
448 return kcm->tx_psock;
449 }
450
451 spin_lock_bh(&mux->lock);
452
453 /* Check again under lock to see if psock was reserved for this
454 * psock via psock_unreserve.
455 */
456 psock = kcm->tx_psock;
457 if (unlikely(psock)) {
458 WARN_ON(kcm->tx_wait);
459 spin_unlock_bh(&mux->lock);
460 return kcm->tx_psock;
461 }
462
463 if (!list_empty(&mux->psocks_avail)) {
464 psock = list_first_entry(&mux->psocks_avail,
465 struct kcm_psock,
466 psock_avail_list);
467 list_del(&psock->psock_avail_list);
468 if (kcm->tx_wait) {
469 list_del(&kcm->wait_psock_list);
470 kcm->tx_wait = false;
471 }
472 kcm->tx_psock = psock;
473 psock->tx_kcm = kcm;
474 KCM_STATS_INCR(psock->stats.reserved);
475 } else if (!kcm->tx_wait) {
476 list_add_tail(&kcm->wait_psock_list,
477 &mux->kcm_tx_waiters);
478 kcm->tx_wait = true;
479 }
480
481 spin_unlock_bh(&mux->lock);
482
483 return psock;
484}
485
486/* mux lock held */
487static void psock_now_avail(struct kcm_psock *psock)
488{
489 struct kcm_mux *mux = psock->mux;
490 struct kcm_sock *kcm;
491
492 if (list_empty(&mux->kcm_tx_waiters)) {
493 list_add_tail(&psock->psock_avail_list,
494 &mux->psocks_avail);
495 } else {
496 kcm = list_first_entry(&mux->kcm_tx_waiters,
497 struct kcm_sock,
498 wait_psock_list);
499 list_del(&kcm->wait_psock_list);
500 kcm->tx_wait = false;
501 psock->tx_kcm = kcm;
502
503 /* Commit before changing tx_psock since that is read in
504 * reserve_psock before queuing work.
505 */
506 smp_mb();
507
508 kcm->tx_psock = psock;
509 KCM_STATS_INCR(psock->stats.reserved);
510 queue_work(kcm_wq, &kcm->tx_work);
511 }
512}
513
514/* kcm sock is locked. */
515static void unreserve_psock(struct kcm_sock *kcm)
516{
517 struct kcm_psock *psock;
518 struct kcm_mux *mux = kcm->mux;
519
520 spin_lock_bh(&mux->lock);
521
522 psock = kcm->tx_psock;
523
524 if (WARN_ON(!psock)) {
525 spin_unlock_bh(&mux->lock);
526 return;
527 }
528
529 smp_rmb(); /* Read tx_psock before tx_wait */
530
531 kcm_update_tx_mux_stats(mux, psock);
532
533 WARN_ON(kcm->tx_wait);
534
535 kcm->tx_psock = NULL;
536 psock->tx_kcm = NULL;
537 KCM_STATS_INCR(psock->stats.unreserved);
538
539 if (unlikely(psock->tx_stopped)) {
540 if (psock->done) {
541 /* Deferred free */
542 list_del(&psock->psock_list);
543 mux->psocks_cnt--;
544 sock_put(psock->sk);
545 fput(psock->sk->sk_socket->file);
546 kmem_cache_free(kcm_psockp, psock);
547 }
548
549 /* Don't put back on available list */
550
551 spin_unlock_bh(&mux->lock);
552
553 return;
554 }
555
556 psock_now_avail(psock);
557
558 spin_unlock_bh(&mux->lock);
559}
560
561static void kcm_report_tx_retry(struct kcm_sock *kcm)
562{
563 struct kcm_mux *mux = kcm->mux;
564
565 spin_lock_bh(&mux->lock);
566 KCM_STATS_INCR(mux->stats.tx_retries);
567 spin_unlock_bh(&mux->lock);
568}
569
570/* Write any messages ready on the kcm socket. Called with kcm sock lock
571 * held. Return bytes actually sent or error.
572 */
573static int kcm_write_msgs(struct kcm_sock *kcm)
574{
575 struct sock *sk = &kcm->sk;
576 struct kcm_psock *psock;
577 struct sk_buff *skb, *head;
578 struct kcm_tx_msg *txm;
579 unsigned short fragidx, frag_offset;
580 unsigned int sent, total_sent = 0;
581 int ret = 0;
582
583 kcm->tx_wait_more = false;
584 psock = kcm->tx_psock;
585 if (unlikely(psock && psock->tx_stopped)) {
586 /* A reserved psock was aborted asynchronously. Unreserve
587 * it and we'll retry the message.
588 */
589 unreserve_psock(kcm);
590 kcm_report_tx_retry(kcm);
591 if (skb_queue_empty(&sk->sk_write_queue))
592 return 0;
593
594 kcm_tx_msg(skb_peek(&sk->sk_write_queue))->sent = 0;
595
596 } else if (skb_queue_empty(&sk->sk_write_queue)) {
597 return 0;
598 }
599
600 head = skb_peek(&sk->sk_write_queue);
601 txm = kcm_tx_msg(head);
602
603 if (txm->sent) {
604 /* Send of first skbuff in queue already in progress */
605 if (WARN_ON(!psock)) {
606 ret = -EINVAL;
607 goto out;
608 }
609 sent = txm->sent;
610 frag_offset = txm->frag_offset;
611 fragidx = txm->fragidx;
612 skb = txm->frag_skb;
613
614 goto do_frag;
615 }
616
617try_again:
618 psock = reserve_psock(kcm);
619 if (!psock)
620 goto out;
621
622 do {
623 skb = head;
624 txm = kcm_tx_msg(head);
625 sent = 0;
626
627do_frag_list:
628 if (WARN_ON(!skb_shinfo(skb)->nr_frags)) {
629 ret = -EINVAL;
630 goto out;
631 }
632
633 for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags;
634 fragidx++) {
635 skb_frag_t *frag;
636
637 frag_offset = 0;
638do_frag:
639 frag = &skb_shinfo(skb)->frags[fragidx];
640 if (WARN_ON(!skb_frag_size(frag))) {
641 ret = -EINVAL;
642 goto out;
643 }
644
645 ret = kernel_sendpage(psock->sk->sk_socket,
646 skb_frag_page(frag),
647 skb_frag_off(frag) + frag_offset,
648 skb_frag_size(frag) - frag_offset,
649 MSG_DONTWAIT);
650 if (ret <= 0) {
651 if (ret == -EAGAIN) {
652 /* Save state to try again when there's
653 * write space on the socket
654 */
655 txm->sent = sent;
656 txm->frag_offset = frag_offset;
657 txm->fragidx = fragidx;
658 txm->frag_skb = skb;
659
660 ret = 0;
661 goto out;
662 }
663
664 /* Hard failure in sending message, abort this
665 * psock since it has lost framing
666 * synchonization and retry sending the
667 * message from the beginning.
668 */
669 kcm_abort_tx_psock(psock, ret ? -ret : EPIPE,
670 true);
671 unreserve_psock(kcm);
672
673 txm->sent = 0;
674 kcm_report_tx_retry(kcm);
675 ret = 0;
676
677 goto try_again;
678 }
679
680 sent += ret;
681 frag_offset += ret;
682 KCM_STATS_ADD(psock->stats.tx_bytes, ret);
683 if (frag_offset < skb_frag_size(frag)) {
684 /* Not finished with this frag */
685 goto do_frag;
686 }
687 }
688
689 if (skb == head) {
690 if (skb_has_frag_list(skb)) {
691 skb = skb_shinfo(skb)->frag_list;
692 goto do_frag_list;
693 }
694 } else if (skb->next) {
695 skb = skb->next;
696 goto do_frag_list;
697 }
698
699 /* Successfully sent the whole packet, account for it. */
700 skb_dequeue(&sk->sk_write_queue);
701 kfree_skb(head);
702 sk->sk_wmem_queued -= sent;
703 total_sent += sent;
704 KCM_STATS_INCR(psock->stats.tx_msgs);
705 } while ((head = skb_peek(&sk->sk_write_queue)));
706out:
707 if (!head) {
708 /* Done with all queued messages. */
709 WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
710 unreserve_psock(kcm);
711 }
712
713 /* Check if write space is available */
714 sk->sk_write_space(sk);
715
716 return total_sent ? : ret;
717}
718
719static void kcm_tx_work(struct work_struct *w)
720{
721 struct kcm_sock *kcm = container_of(w, struct kcm_sock, tx_work);
722 struct sock *sk = &kcm->sk;
723 int err;
724
725 lock_sock(sk);
726
727 /* Primarily for SOCK_DGRAM sockets, also handle asynchronous tx
728 * aborts
729 */
730 err = kcm_write_msgs(kcm);
731 if (err < 0) {
732 /* Hard failure in write, report error on KCM socket */
733 pr_warn("KCM: Hard failure on kcm_write_msgs %d\n", err);
734 report_csk_error(&kcm->sk, -err);
735 goto out;
736 }
737
738 /* Primarily for SOCK_SEQPACKET sockets */
739 if (likely(sk->sk_socket) &&
740 test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
741 clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
742 sk->sk_write_space(sk);
743 }
744
745out:
746 release_sock(sk);
747}
748
749static void kcm_push(struct kcm_sock *kcm)
750{
751 if (kcm->tx_wait_more)
752 kcm_write_msgs(kcm);
753}
754
755static ssize_t kcm_sendpage(struct socket *sock, struct page *page,
756 int offset, size_t size, int flags)
757
758{
759 struct sock *sk = sock->sk;
760 struct kcm_sock *kcm = kcm_sk(sk);
761 struct sk_buff *skb = NULL, *head = NULL;
762 long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
763 bool eor;
764 int err = 0;
765 int i;
766
767 if (flags & MSG_SENDPAGE_NOTLAST)
768 flags |= MSG_MORE;
769
770 /* No MSG_EOR from splice, only look at MSG_MORE */
771 eor = !(flags & MSG_MORE);
772
773 lock_sock(sk);
774
775 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
776
777 err = -EPIPE;
778 if (sk->sk_err)
779 goto out_error;
780
781 if (kcm->seq_skb) {
782 /* Previously opened message */
783 head = kcm->seq_skb;
784 skb = kcm_tx_msg(head)->last_skb;
785 i = skb_shinfo(skb)->nr_frags;
786
787 if (skb_can_coalesce(skb, i, page, offset)) {
788 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
789 skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
790 goto coalesced;
791 }
792
793 if (i >= MAX_SKB_FRAGS) {
794 struct sk_buff *tskb;
795
796 tskb = alloc_skb(0, sk->sk_allocation);
797 while (!tskb) {
798 kcm_push(kcm);
799 err = sk_stream_wait_memory(sk, &timeo);
800 if (err)
801 goto out_error;
802 }
803
804 if (head == skb)
805 skb_shinfo(head)->frag_list = tskb;
806 else
807 skb->next = tskb;
808
809 skb = tskb;
810 skb->ip_summed = CHECKSUM_UNNECESSARY;
811 i = 0;
812 }
813 } else {
814 /* Call the sk_stream functions to manage the sndbuf mem. */
815 if (!sk_stream_memory_free(sk)) {
816 kcm_push(kcm);
817 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
818 err = sk_stream_wait_memory(sk, &timeo);
819 if (err)
820 goto out_error;
821 }
822
823 head = alloc_skb(0, sk->sk_allocation);
824 while (!head) {
825 kcm_push(kcm);
826 err = sk_stream_wait_memory(sk, &timeo);
827 if (err)
828 goto out_error;
829 }
830
831 skb = head;
832 i = 0;
833 }
834
835 get_page(page);
836 skb_fill_page_desc(skb, i, page, offset, size);
837 skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
838
839coalesced:
840 skb->len += size;
841 skb->data_len += size;
842 skb->truesize += size;
843 sk->sk_wmem_queued += size;
844 sk_mem_charge(sk, size);
845
846 if (head != skb) {
847 head->len += size;
848 head->data_len += size;
849 head->truesize += size;
850 }
851
852 if (eor) {
853 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
854
855 /* Message complete, queue it on send buffer */
856 __skb_queue_tail(&sk->sk_write_queue, head);
857 kcm->seq_skb = NULL;
858 KCM_STATS_INCR(kcm->stats.tx_msgs);
859
860 if (flags & MSG_BATCH) {
861 kcm->tx_wait_more = true;
862 } else if (kcm->tx_wait_more || not_busy) {
863 err = kcm_write_msgs(kcm);
864 if (err < 0) {
865 /* We got a hard error in write_msgs but have
866 * already queued this message. Report an error
867 * in the socket, but don't affect return value
868 * from sendmsg
869 */
870 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
871 report_csk_error(&kcm->sk, -err);
872 }
873 }
874 } else {
875 /* Message not complete, save state */
876 kcm->seq_skb = head;
877 kcm_tx_msg(head)->last_skb = skb;
878 }
879
880 KCM_STATS_ADD(kcm->stats.tx_bytes, size);
881
882 release_sock(sk);
883 return size;
884
885out_error:
886 kcm_push(kcm);
887
888 err = sk_stream_error(sk, flags, err);
889
890 /* make sure we wake any epoll edge trigger waiter */
891 if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
892 sk->sk_write_space(sk);
893
894 release_sock(sk);
895 return err;
896}
897
898static int kcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
899{
900 struct sock *sk = sock->sk;
901 struct kcm_sock *kcm = kcm_sk(sk);
902 struct sk_buff *skb = NULL, *head = NULL;
903 size_t copy, copied = 0;
904 long timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
905 int eor = (sock->type == SOCK_DGRAM) ?
906 !(msg->msg_flags & MSG_MORE) : !!(msg->msg_flags & MSG_EOR);
907 int err = -EPIPE;
908
909 lock_sock(sk);
910
911 /* Per tcp_sendmsg this should be in poll */
912 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
913
914 if (sk->sk_err)
915 goto out_error;
916
917 if (kcm->seq_skb) {
918 /* Previously opened message */
919 head = kcm->seq_skb;
920 skb = kcm_tx_msg(head)->last_skb;
921 goto start;
922 }
923
924 /* Call the sk_stream functions to manage the sndbuf mem. */
925 if (!sk_stream_memory_free(sk)) {
926 kcm_push(kcm);
927 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
928 err = sk_stream_wait_memory(sk, &timeo);
929 if (err)
930 goto out_error;
931 }
932
933 if (msg_data_left(msg)) {
934 /* New message, alloc head skb */
935 head = alloc_skb(0, sk->sk_allocation);
936 while (!head) {
937 kcm_push(kcm);
938 err = sk_stream_wait_memory(sk, &timeo);
939 if (err)
940 goto out_error;
941
942 head = alloc_skb(0, sk->sk_allocation);
943 }
944
945 skb = head;
946
947 /* Set ip_summed to CHECKSUM_UNNECESSARY to avoid calling
948 * csum_and_copy_from_iter from skb_do_copy_data_nocache.
949 */
950 skb->ip_summed = CHECKSUM_UNNECESSARY;
951 }
952
953start:
954 while (msg_data_left(msg)) {
955 bool merge = true;
956 int i = skb_shinfo(skb)->nr_frags;
957 struct page_frag *pfrag = sk_page_frag(sk);
958
959 if (!sk_page_frag_refill(sk, pfrag))
960 goto wait_for_memory;
961
962 if (!skb_can_coalesce(skb, i, pfrag->page,
963 pfrag->offset)) {
964 if (i == MAX_SKB_FRAGS) {
965 struct sk_buff *tskb;
966
967 tskb = alloc_skb(0, sk->sk_allocation);
968 if (!tskb)
969 goto wait_for_memory;
970
971 if (head == skb)
972 skb_shinfo(head)->frag_list = tskb;
973 else
974 skb->next = tskb;
975
976 skb = tskb;
977 skb->ip_summed = CHECKSUM_UNNECESSARY;
978 continue;
979 }
980 merge = false;
981 }
982
983 copy = min_t(int, msg_data_left(msg),
984 pfrag->size - pfrag->offset);
985
986 if (!sk_wmem_schedule(sk, copy))
987 goto wait_for_memory;
988
989 err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
990 pfrag->page,
991 pfrag->offset,
992 copy);
993 if (err)
994 goto out_error;
995
996 /* Update the skb. */
997 if (merge) {
998 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
999 } else {
1000 skb_fill_page_desc(skb, i, pfrag->page,
1001 pfrag->offset, copy);
1002 get_page(pfrag->page);
1003 }
1004
1005 pfrag->offset += copy;
1006 copied += copy;
1007 if (head != skb) {
1008 head->len += copy;
1009 head->data_len += copy;
1010 }
1011
1012 continue;
1013
1014wait_for_memory:
1015 kcm_push(kcm);
1016 err = sk_stream_wait_memory(sk, &timeo);
1017 if (err)
1018 goto out_error;
1019 }
1020
1021 if (eor) {
1022 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
1023
1024 if (head) {
1025 /* Message complete, queue it on send buffer */
1026 __skb_queue_tail(&sk->sk_write_queue, head);
1027 kcm->seq_skb = NULL;
1028 KCM_STATS_INCR(kcm->stats.tx_msgs);
1029 }
1030
1031 if (msg->msg_flags & MSG_BATCH) {
1032 kcm->tx_wait_more = true;
1033 } else if (kcm->tx_wait_more || not_busy) {
1034 err = kcm_write_msgs(kcm);
1035 if (err < 0) {
1036 /* We got a hard error in write_msgs but have
1037 * already queued this message. Report an error
1038 * in the socket, but don't affect return value
1039 * from sendmsg
1040 */
1041 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
1042 report_csk_error(&kcm->sk, -err);
1043 }
1044 }
1045 } else {
1046 /* Message not complete, save state */
1047partial_message:
1048 if (head) {
1049 kcm->seq_skb = head;
1050 kcm_tx_msg(head)->last_skb = skb;
1051 }
1052 }
1053
1054 KCM_STATS_ADD(kcm->stats.tx_bytes, copied);
1055
1056 release_sock(sk);
1057 return copied;
1058
1059out_error:
1060 kcm_push(kcm);
1061
1062 if (copied && sock->type == SOCK_SEQPACKET) {
1063 /* Wrote some bytes before encountering an
1064 * error, return partial success.
1065 */
1066 goto partial_message;
1067 }
1068
1069 if (head != kcm->seq_skb)
1070 kfree_skb(head);
1071
1072 err = sk_stream_error(sk, msg->msg_flags, err);
1073
1074 /* make sure we wake any epoll edge trigger waiter */
1075 if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
1076 sk->sk_write_space(sk);
1077
1078 release_sock(sk);
1079 return err;
1080}
1081
1082static struct sk_buff *kcm_wait_data(struct sock *sk, int flags,
1083 long timeo, int *err)
1084{
1085 struct sk_buff *skb;
1086
1087 while (!(skb = skb_peek(&sk->sk_receive_queue))) {
1088 if (sk->sk_err) {
1089 *err = sock_error(sk);
1090 return NULL;
1091 }
1092
1093 if (sock_flag(sk, SOCK_DONE))
1094 return NULL;
1095
1096 if ((flags & MSG_DONTWAIT) || !timeo) {
1097 *err = -EAGAIN;
1098 return NULL;
1099 }
1100
1101 sk_wait_data(sk, &timeo, NULL);
1102
1103 /* Handle signals */
1104 if (signal_pending(current)) {
1105 *err = sock_intr_errno(timeo);
1106 return NULL;
1107 }
1108 }
1109
1110 return skb;
1111}
1112
1113static int kcm_recvmsg(struct socket *sock, struct msghdr *msg,
1114 size_t len, int flags)
1115{
1116 struct sock *sk = sock->sk;
1117 struct kcm_sock *kcm = kcm_sk(sk);
1118 int err = 0;
1119 long timeo;
1120 struct strp_msg *stm;
1121 int copied = 0;
1122 struct sk_buff *skb;
1123
1124 timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
1125
1126 lock_sock(sk);
1127
1128 skb = kcm_wait_data(sk, flags, timeo, &err);
1129 if (!skb)
1130 goto out;
1131
1132 /* Okay, have a message on the receive queue */
1133
1134 stm = strp_msg(skb);
1135
1136 if (len > stm->full_len)
1137 len = stm->full_len;
1138
1139 err = skb_copy_datagram_msg(skb, stm->offset, msg, len);
1140 if (err < 0)
1141 goto out;
1142
1143 copied = len;
1144 if (likely(!(flags & MSG_PEEK))) {
1145 KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1146 if (copied < stm->full_len) {
1147 if (sock->type == SOCK_DGRAM) {
1148 /* Truncated message */
1149 msg->msg_flags |= MSG_TRUNC;
1150 goto msg_finished;
1151 }
1152 stm->offset += copied;
1153 stm->full_len -= copied;
1154 } else {
1155msg_finished:
1156 /* Finished with message */
1157 msg->msg_flags |= MSG_EOR;
1158 KCM_STATS_INCR(kcm->stats.rx_msgs);
1159 skb_unlink(skb, &sk->sk_receive_queue);
1160 kfree_skb(skb);
1161 }
1162 }
1163
1164out:
1165 release_sock(sk);
1166
1167 return copied ? : err;
1168}
1169
1170static ssize_t kcm_splice_read(struct socket *sock, loff_t *ppos,
1171 struct pipe_inode_info *pipe, size_t len,
1172 unsigned int flags)
1173{
1174 struct sock *sk = sock->sk;
1175 struct kcm_sock *kcm = kcm_sk(sk);
1176 long timeo;
1177 struct strp_msg *stm;
1178 int err = 0;
1179 ssize_t copied;
1180 struct sk_buff *skb;
1181
1182 /* Only support splice for SOCKSEQPACKET */
1183
1184 timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
1185
1186 lock_sock(sk);
1187
1188 skb = kcm_wait_data(sk, flags, timeo, &err);
1189 if (!skb)
1190 goto err_out;
1191
1192 /* Okay, have a message on the receive queue */
1193
1194 stm = strp_msg(skb);
1195
1196 if (len > stm->full_len)
1197 len = stm->full_len;
1198
1199 copied = skb_splice_bits(skb, sk, stm->offset, pipe, len, flags);
1200 if (copied < 0) {
1201 err = copied;
1202 goto err_out;
1203 }
1204
1205 KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1206
1207 stm->offset += copied;
1208 stm->full_len -= copied;
1209
1210 /* We have no way to return MSG_EOR. If all the bytes have been
1211 * read we still leave the message in the receive socket buffer.
1212 * A subsequent recvmsg needs to be done to return MSG_EOR and
1213 * finish reading the message.
1214 */
1215
1216 release_sock(sk);
1217
1218 return copied;
1219
1220err_out:
1221 release_sock(sk);
1222
1223 return err;
1224}
1225
1226/* kcm sock lock held */
1227static void kcm_recv_disable(struct kcm_sock *kcm)
1228{
1229 struct kcm_mux *mux = kcm->mux;
1230
1231 if (kcm->rx_disabled)
1232 return;
1233
1234 spin_lock_bh(&mux->rx_lock);
1235
1236 kcm->rx_disabled = 1;
1237
1238 /* If a psock is reserved we'll do cleanup in unreserve */
1239 if (!kcm->rx_psock) {
1240 if (kcm->rx_wait) {
1241 list_del(&kcm->wait_rx_list);
1242 kcm->rx_wait = false;
1243 }
1244
1245 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
1246 }
1247
1248 spin_unlock_bh(&mux->rx_lock);
1249}
1250
1251/* kcm sock lock held */
1252static void kcm_recv_enable(struct kcm_sock *kcm)
1253{
1254 struct kcm_mux *mux = kcm->mux;
1255
1256 if (!kcm->rx_disabled)
1257 return;
1258
1259 spin_lock_bh(&mux->rx_lock);
1260
1261 kcm->rx_disabled = 0;
1262 kcm_rcv_ready(kcm);
1263
1264 spin_unlock_bh(&mux->rx_lock);
1265}
1266
1267static int kcm_setsockopt(struct socket *sock, int level, int optname,
1268 sockptr_t optval, unsigned int optlen)
1269{
1270 struct kcm_sock *kcm = kcm_sk(sock->sk);
1271 int val, valbool;
1272 int err = 0;
1273
1274 if (level != SOL_KCM)
1275 return -ENOPROTOOPT;
1276
1277 if (optlen < sizeof(int))
1278 return -EINVAL;
1279
1280 if (copy_from_sockptr(&val, optval, sizeof(int)))
1281 return -EFAULT;
1282
1283 valbool = val ? 1 : 0;
1284
1285 switch (optname) {
1286 case KCM_RECV_DISABLE:
1287 lock_sock(&kcm->sk);
1288 if (valbool)
1289 kcm_recv_disable(kcm);
1290 else
1291 kcm_recv_enable(kcm);
1292 release_sock(&kcm->sk);
1293 break;
1294 default:
1295 err = -ENOPROTOOPT;
1296 }
1297
1298 return err;
1299}
1300
1301static int kcm_getsockopt(struct socket *sock, int level, int optname,
1302 char __user *optval, int __user *optlen)
1303{
1304 struct kcm_sock *kcm = kcm_sk(sock->sk);
1305 int val, len;
1306
1307 if (level != SOL_KCM)
1308 return -ENOPROTOOPT;
1309
1310 if (get_user(len, optlen))
1311 return -EFAULT;
1312
1313 len = min_t(unsigned int, len, sizeof(int));
1314 if (len < 0)
1315 return -EINVAL;
1316
1317 switch (optname) {
1318 case KCM_RECV_DISABLE:
1319 val = kcm->rx_disabled;
1320 break;
1321 default:
1322 return -ENOPROTOOPT;
1323 }
1324
1325 if (put_user(len, optlen))
1326 return -EFAULT;
1327 if (copy_to_user(optval, &val, len))
1328 return -EFAULT;
1329 return 0;
1330}
1331
1332static void init_kcm_sock(struct kcm_sock *kcm, struct kcm_mux *mux)
1333{
1334 struct kcm_sock *tkcm;
1335 struct list_head *head;
1336 int index = 0;
1337
1338 /* For SOCK_SEQPACKET sock type, datagram_poll checks the sk_state, so
1339 * we set sk_state, otherwise epoll_wait always returns right away with
1340 * EPOLLHUP
1341 */
1342 kcm->sk.sk_state = TCP_ESTABLISHED;
1343
1344 /* Add to mux's kcm sockets list */
1345 kcm->mux = mux;
1346 spin_lock_bh(&mux->lock);
1347
1348 head = &mux->kcm_socks;
1349 list_for_each_entry(tkcm, &mux->kcm_socks, kcm_sock_list) {
1350 if (tkcm->index != index)
1351 break;
1352 head = &tkcm->kcm_sock_list;
1353 index++;
1354 }
1355
1356 list_add(&kcm->kcm_sock_list, head);
1357 kcm->index = index;
1358
1359 mux->kcm_socks_cnt++;
1360 spin_unlock_bh(&mux->lock);
1361
1362 INIT_WORK(&kcm->tx_work, kcm_tx_work);
1363
1364 spin_lock_bh(&mux->rx_lock);
1365 kcm_rcv_ready(kcm);
1366 spin_unlock_bh(&mux->rx_lock);
1367}
1368
1369static int kcm_attach(struct socket *sock, struct socket *csock,
1370 struct bpf_prog *prog)
1371{
1372 struct kcm_sock *kcm = kcm_sk(sock->sk);
1373 struct kcm_mux *mux = kcm->mux;
1374 struct sock *csk;
1375 struct kcm_psock *psock = NULL, *tpsock;
1376 struct list_head *head;
1377 int index = 0;
1378 static const struct strp_callbacks cb = {
1379 .rcv_msg = kcm_rcv_strparser,
1380 .parse_msg = kcm_parse_func_strparser,
1381 .read_sock_done = kcm_read_sock_done,
1382 };
1383 int err = 0;
1384
1385 csk = csock->sk;
1386 if (!csk)
1387 return -EINVAL;
1388
1389 lock_sock(csk);
1390
1391 /* Only allow TCP sockets to be attached for now */
1392 if ((csk->sk_family != AF_INET && csk->sk_family != AF_INET6) ||
1393 csk->sk_protocol != IPPROTO_TCP) {
1394 err = -EOPNOTSUPP;
1395 goto out;
1396 }
1397
1398 /* Don't allow listeners or closed sockets */
1399 if (csk->sk_state == TCP_LISTEN || csk->sk_state == TCP_CLOSE) {
1400 err = -EOPNOTSUPP;
1401 goto out;
1402 }
1403
1404 psock = kmem_cache_zalloc(kcm_psockp, GFP_KERNEL);
1405 if (!psock) {
1406 err = -ENOMEM;
1407 goto out;
1408 }
1409
1410 psock->mux = mux;
1411 psock->sk = csk;
1412 psock->bpf_prog = prog;
1413
1414 err = strp_init(&psock->strp, csk, &cb);
1415 if (err) {
1416 kmem_cache_free(kcm_psockp, psock);
1417 goto out;
1418 }
1419
1420 write_lock_bh(&csk->sk_callback_lock);
1421
1422 /* Check if sk_user_data is aready by KCM or someone else.
1423 * Must be done under lock to prevent race conditions.
1424 */
1425 if (csk->sk_user_data) {
1426 write_unlock_bh(&csk->sk_callback_lock);
1427 strp_stop(&psock->strp);
1428 strp_done(&psock->strp);
1429 kmem_cache_free(kcm_psockp, psock);
1430 err = -EALREADY;
1431 goto out;
1432 }
1433
1434 psock->save_data_ready = csk->sk_data_ready;
1435 psock->save_write_space = csk->sk_write_space;
1436 psock->save_state_change = csk->sk_state_change;
1437 csk->sk_user_data = psock;
1438 csk->sk_data_ready = psock_data_ready;
1439 csk->sk_write_space = psock_write_space;
1440 csk->sk_state_change = psock_state_change;
1441
1442 write_unlock_bh(&csk->sk_callback_lock);
1443
1444 sock_hold(csk);
1445
1446 /* Finished initialization, now add the psock to the MUX. */
1447 spin_lock_bh(&mux->lock);
1448 head = &mux->psocks;
1449 list_for_each_entry(tpsock, &mux->psocks, psock_list) {
1450 if (tpsock->index != index)
1451 break;
1452 head = &tpsock->psock_list;
1453 index++;
1454 }
1455
1456 list_add(&psock->psock_list, head);
1457 psock->index = index;
1458
1459 KCM_STATS_INCR(mux->stats.psock_attach);
1460 mux->psocks_cnt++;
1461 psock_now_avail(psock);
1462 spin_unlock_bh(&mux->lock);
1463
1464 /* Schedule RX work in case there are already bytes queued */
1465 strp_check_rcv(&psock->strp);
1466
1467out:
1468 release_sock(csk);
1469
1470 return err;
1471}
1472
1473static int kcm_attach_ioctl(struct socket *sock, struct kcm_attach *info)
1474{
1475 struct socket *csock;
1476 struct bpf_prog *prog;
1477 int err;
1478
1479 csock = sockfd_lookup(info->fd, &err);
1480 if (!csock)
1481 return -ENOENT;
1482
1483 prog = bpf_prog_get_type(info->bpf_fd, BPF_PROG_TYPE_SOCKET_FILTER);
1484 if (IS_ERR(prog)) {
1485 err = PTR_ERR(prog);
1486 goto out;
1487 }
1488
1489 err = kcm_attach(sock, csock, prog);
1490 if (err) {
1491 bpf_prog_put(prog);
1492 goto out;
1493 }
1494
1495 /* Keep reference on file also */
1496
1497 return 0;
1498out:
1499 fput(csock->file);
1500 return err;
1501}
1502
1503static void kcm_unattach(struct kcm_psock *psock)
1504{
1505 struct sock *csk = psock->sk;
1506 struct kcm_mux *mux = psock->mux;
1507
1508 lock_sock(csk);
1509
1510 /* Stop getting callbacks from TCP socket. After this there should
1511 * be no way to reserve a kcm for this psock.
1512 */
1513 write_lock_bh(&csk->sk_callback_lock);
1514 csk->sk_user_data = NULL;
1515 csk->sk_data_ready = psock->save_data_ready;
1516 csk->sk_write_space = psock->save_write_space;
1517 csk->sk_state_change = psock->save_state_change;
1518 strp_stop(&psock->strp);
1519
1520 if (WARN_ON(psock->rx_kcm)) {
1521 write_unlock_bh(&csk->sk_callback_lock);
1522 release_sock(csk);
1523 return;
1524 }
1525
1526 spin_lock_bh(&mux->rx_lock);
1527
1528 /* Stop receiver activities. After this point psock should not be
1529 * able to get onto ready list either through callbacks or work.
1530 */
1531 if (psock->ready_rx_msg) {
1532 list_del(&psock->psock_ready_list);
1533 kfree_skb(psock->ready_rx_msg);
1534 psock->ready_rx_msg = NULL;
1535 KCM_STATS_INCR(mux->stats.rx_ready_drops);
1536 }
1537
1538 spin_unlock_bh(&mux->rx_lock);
1539
1540 write_unlock_bh(&csk->sk_callback_lock);
1541
1542 /* Call strp_done without sock lock */
1543 release_sock(csk);
1544 strp_done(&psock->strp);
1545 lock_sock(csk);
1546
1547 bpf_prog_put(psock->bpf_prog);
1548
1549 spin_lock_bh(&mux->lock);
1550
1551 aggregate_psock_stats(&psock->stats, &mux->aggregate_psock_stats);
1552 save_strp_stats(&psock->strp, &mux->aggregate_strp_stats);
1553
1554 KCM_STATS_INCR(mux->stats.psock_unattach);
1555
1556 if (psock->tx_kcm) {
1557 /* psock was reserved. Just mark it finished and we will clean
1558 * up in the kcm paths, we need kcm lock which can not be
1559 * acquired here.
1560 */
1561 KCM_STATS_INCR(mux->stats.psock_unattach_rsvd);
1562 spin_unlock_bh(&mux->lock);
1563
1564 /* We are unattaching a socket that is reserved. Abort the
1565 * socket since we may be out of sync in sending on it. We need
1566 * to do this without the mux lock.
1567 */
1568 kcm_abort_tx_psock(psock, EPIPE, false);
1569
1570 spin_lock_bh(&mux->lock);
1571 if (!psock->tx_kcm) {
1572 /* psock now unreserved in window mux was unlocked */
1573 goto no_reserved;
1574 }
1575 psock->done = 1;
1576
1577 /* Commit done before queuing work to process it */
1578 smp_mb();
1579
1580 /* Queue tx work to make sure psock->done is handled */
1581 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
1582 spin_unlock_bh(&mux->lock);
1583 } else {
1584no_reserved:
1585 if (!psock->tx_stopped)
1586 list_del(&psock->psock_avail_list);
1587 list_del(&psock->psock_list);
1588 mux->psocks_cnt--;
1589 spin_unlock_bh(&mux->lock);
1590
1591 sock_put(csk);
1592 fput(csk->sk_socket->file);
1593 kmem_cache_free(kcm_psockp, psock);
1594 }
1595
1596 release_sock(csk);
1597}
1598
1599static int kcm_unattach_ioctl(struct socket *sock, struct kcm_unattach *info)
1600{
1601 struct kcm_sock *kcm = kcm_sk(sock->sk);
1602 struct kcm_mux *mux = kcm->mux;
1603 struct kcm_psock *psock;
1604 struct socket *csock;
1605 struct sock *csk;
1606 int err;
1607
1608 csock = sockfd_lookup(info->fd, &err);
1609 if (!csock)
1610 return -ENOENT;
1611
1612 csk = csock->sk;
1613 if (!csk) {
1614 err = -EINVAL;
1615 goto out;
1616 }
1617
1618 err = -ENOENT;
1619
1620 spin_lock_bh(&mux->lock);
1621
1622 list_for_each_entry(psock, &mux->psocks, psock_list) {
1623 if (psock->sk != csk)
1624 continue;
1625
1626 /* Found the matching psock */
1627
1628 if (psock->unattaching || WARN_ON(psock->done)) {
1629 err = -EALREADY;
1630 break;
1631 }
1632
1633 psock->unattaching = 1;
1634
1635 spin_unlock_bh(&mux->lock);
1636
1637 /* Lower socket lock should already be held */
1638 kcm_unattach(psock);
1639
1640 err = 0;
1641 goto out;
1642 }
1643
1644 spin_unlock_bh(&mux->lock);
1645
1646out:
1647 fput(csock->file);
1648 return err;
1649}
1650
1651static struct proto kcm_proto = {
1652 .name = "KCM",
1653 .owner = THIS_MODULE,
1654 .obj_size = sizeof(struct kcm_sock),
1655};
1656
1657/* Clone a kcm socket. */
1658static struct file *kcm_clone(struct socket *osock)
1659{
1660 struct socket *newsock;
1661 struct sock *newsk;
1662
1663 newsock = sock_alloc();
1664 if (!newsock)
1665 return ERR_PTR(-ENFILE);
1666
1667 newsock->type = osock->type;
1668 newsock->ops = osock->ops;
1669
1670 __module_get(newsock->ops->owner);
1671
1672 newsk = sk_alloc(sock_net(osock->sk), PF_KCM, GFP_KERNEL,
1673 &kcm_proto, false);
1674 if (!newsk) {
1675 sock_release(newsock);
1676 return ERR_PTR(-ENOMEM);
1677 }
1678 sock_init_data(newsock, newsk);
1679 init_kcm_sock(kcm_sk(newsk), kcm_sk(osock->sk)->mux);
1680
1681 return sock_alloc_file(newsock, 0, osock->sk->sk_prot_creator->name);
1682}
1683
1684static int kcm_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
1685{
1686 int err;
1687
1688 switch (cmd) {
1689 case SIOCKCMATTACH: {
1690 struct kcm_attach info;
1691
1692 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1693 return -EFAULT;
1694
1695 err = kcm_attach_ioctl(sock, &info);
1696
1697 break;
1698 }
1699 case SIOCKCMUNATTACH: {
1700 struct kcm_unattach info;
1701
1702 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1703 return -EFAULT;
1704
1705 err = kcm_unattach_ioctl(sock, &info);
1706
1707 break;
1708 }
1709 case SIOCKCMCLONE: {
1710 struct kcm_clone info;
1711 struct file *file;
1712
1713 info.fd = get_unused_fd_flags(0);
1714 if (unlikely(info.fd < 0))
1715 return info.fd;
1716
1717 file = kcm_clone(sock);
1718 if (IS_ERR(file)) {
1719 put_unused_fd(info.fd);
1720 return PTR_ERR(file);
1721 }
1722 if (copy_to_user((void __user *)arg, &info,
1723 sizeof(info))) {
1724 put_unused_fd(info.fd);
1725 fput(file);
1726 return -EFAULT;
1727 }
1728 fd_install(info.fd, file);
1729 err = 0;
1730 break;
1731 }
1732 default:
1733 err = -ENOIOCTLCMD;
1734 break;
1735 }
1736
1737 return err;
1738}
1739
1740static void free_mux(struct rcu_head *rcu)
1741{
1742 struct kcm_mux *mux = container_of(rcu,
1743 struct kcm_mux, rcu);
1744
1745 kmem_cache_free(kcm_muxp, mux);
1746}
1747
1748static void release_mux(struct kcm_mux *mux)
1749{
1750 struct kcm_net *knet = mux->knet;
1751 struct kcm_psock *psock, *tmp_psock;
1752
1753 /* Release psocks */
1754 list_for_each_entry_safe(psock, tmp_psock,
1755 &mux->psocks, psock_list) {
1756 if (!WARN_ON(psock->unattaching))
1757 kcm_unattach(psock);
1758 }
1759
1760 if (WARN_ON(mux->psocks_cnt))
1761 return;
1762
1763 __skb_queue_purge(&mux->rx_hold_queue);
1764
1765 mutex_lock(&knet->mutex);
1766 aggregate_mux_stats(&mux->stats, &knet->aggregate_mux_stats);
1767 aggregate_psock_stats(&mux->aggregate_psock_stats,
1768 &knet->aggregate_psock_stats);
1769 aggregate_strp_stats(&mux->aggregate_strp_stats,
1770 &knet->aggregate_strp_stats);
1771 list_del_rcu(&mux->kcm_mux_list);
1772 knet->count--;
1773 mutex_unlock(&knet->mutex);
1774
1775 call_rcu(&mux->rcu, free_mux);
1776}
1777
1778static void kcm_done(struct kcm_sock *kcm)
1779{
1780 struct kcm_mux *mux = kcm->mux;
1781 struct sock *sk = &kcm->sk;
1782 int socks_cnt;
1783
1784 spin_lock_bh(&mux->rx_lock);
1785 if (kcm->rx_psock) {
1786 /* Cleanup in unreserve_rx_kcm */
1787 WARN_ON(kcm->done);
1788 kcm->rx_disabled = 1;
1789 kcm->done = 1;
1790 spin_unlock_bh(&mux->rx_lock);
1791 return;
1792 }
1793
1794 if (kcm->rx_wait) {
1795 list_del(&kcm->wait_rx_list);
1796 kcm->rx_wait = false;
1797 }
1798 /* Move any pending receive messages to other kcm sockets */
1799 requeue_rx_msgs(mux, &sk->sk_receive_queue);
1800
1801 spin_unlock_bh(&mux->rx_lock);
1802
1803 if (WARN_ON(sk_rmem_alloc_get(sk)))
1804 return;
1805
1806 /* Detach from MUX */
1807 spin_lock_bh(&mux->lock);
1808
1809 list_del(&kcm->kcm_sock_list);
1810 mux->kcm_socks_cnt--;
1811 socks_cnt = mux->kcm_socks_cnt;
1812
1813 spin_unlock_bh(&mux->lock);
1814
1815 if (!socks_cnt) {
1816 /* We are done with the mux now. */
1817 release_mux(mux);
1818 }
1819
1820 WARN_ON(kcm->rx_wait);
1821
1822 sock_put(&kcm->sk);
1823}
1824
1825/* Called by kcm_release to close a KCM socket.
1826 * If this is the last KCM socket on the MUX, destroy the MUX.
1827 */
1828static int kcm_release(struct socket *sock)
1829{
1830 struct sock *sk = sock->sk;
1831 struct kcm_sock *kcm;
1832 struct kcm_mux *mux;
1833 struct kcm_psock *psock;
1834
1835 if (!sk)
1836 return 0;
1837
1838 kcm = kcm_sk(sk);
1839 mux = kcm->mux;
1840
1841 sock_orphan(sk);
1842 kfree_skb(kcm->seq_skb);
1843
1844 lock_sock(sk);
1845 /* Purge queue under lock to avoid race condition with tx_work trying
1846 * to act when queue is nonempty. If tx_work runs after this point
1847 * it will just return.
1848 */
1849 __skb_queue_purge(&sk->sk_write_queue);
1850
1851 /* Set tx_stopped. This is checked when psock is bound to a kcm and we
1852 * get a writespace callback. This prevents further work being queued
1853 * from the callback (unbinding the psock occurs after canceling work.
1854 */
1855 kcm->tx_stopped = 1;
1856
1857 release_sock(sk);
1858
1859 spin_lock_bh(&mux->lock);
1860 if (kcm->tx_wait) {
1861 /* Take of tx_wait list, after this point there should be no way
1862 * that a psock will be assigned to this kcm.
1863 */
1864 list_del(&kcm->wait_psock_list);
1865 kcm->tx_wait = false;
1866 }
1867 spin_unlock_bh(&mux->lock);
1868
1869 /* Cancel work. After this point there should be no outside references
1870 * to the kcm socket.
1871 */
1872 cancel_work_sync(&kcm->tx_work);
1873
1874 lock_sock(sk);
1875 psock = kcm->tx_psock;
1876 if (psock) {
1877 /* A psock was reserved, so we need to kill it since it
1878 * may already have some bytes queued from a message. We
1879 * need to do this after removing kcm from tx_wait list.
1880 */
1881 kcm_abort_tx_psock(psock, EPIPE, false);
1882 unreserve_psock(kcm);
1883 }
1884 release_sock(sk);
1885
1886 WARN_ON(kcm->tx_wait);
1887 WARN_ON(kcm->tx_psock);
1888
1889 sock->sk = NULL;
1890
1891 kcm_done(kcm);
1892
1893 return 0;
1894}
1895
1896static const struct proto_ops kcm_dgram_ops = {
1897 .family = PF_KCM,
1898 .owner = THIS_MODULE,
1899 .release = kcm_release,
1900 .bind = sock_no_bind,
1901 .connect = sock_no_connect,
1902 .socketpair = sock_no_socketpair,
1903 .accept = sock_no_accept,
1904 .getname = sock_no_getname,
1905 .poll = datagram_poll,
1906 .ioctl = kcm_ioctl,
1907 .listen = sock_no_listen,
1908 .shutdown = sock_no_shutdown,
1909 .setsockopt = kcm_setsockopt,
1910 .getsockopt = kcm_getsockopt,
1911 .sendmsg = kcm_sendmsg,
1912 .recvmsg = kcm_recvmsg,
1913 .mmap = sock_no_mmap,
1914 .sendpage = kcm_sendpage,
1915};
1916
1917static const struct proto_ops kcm_seqpacket_ops = {
1918 .family = PF_KCM,
1919 .owner = THIS_MODULE,
1920 .release = kcm_release,
1921 .bind = sock_no_bind,
1922 .connect = sock_no_connect,
1923 .socketpair = sock_no_socketpair,
1924 .accept = sock_no_accept,
1925 .getname = sock_no_getname,
1926 .poll = datagram_poll,
1927 .ioctl = kcm_ioctl,
1928 .listen = sock_no_listen,
1929 .shutdown = sock_no_shutdown,
1930 .setsockopt = kcm_setsockopt,
1931 .getsockopt = kcm_getsockopt,
1932 .sendmsg = kcm_sendmsg,
1933 .recvmsg = kcm_recvmsg,
1934 .mmap = sock_no_mmap,
1935 .sendpage = kcm_sendpage,
1936 .splice_read = kcm_splice_read,
1937};
1938
1939/* Create proto operation for kcm sockets */
1940static int kcm_create(struct net *net, struct socket *sock,
1941 int protocol, int kern)
1942{
1943 struct kcm_net *knet = net_generic(net, kcm_net_id);
1944 struct sock *sk;
1945 struct kcm_mux *mux;
1946
1947 switch (sock->type) {
1948 case SOCK_DGRAM:
1949 sock->ops = &kcm_dgram_ops;
1950 break;
1951 case SOCK_SEQPACKET:
1952 sock->ops = &kcm_seqpacket_ops;
1953 break;
1954 default:
1955 return -ESOCKTNOSUPPORT;
1956 }
1957
1958 if (protocol != KCMPROTO_CONNECTED)
1959 return -EPROTONOSUPPORT;
1960
1961 sk = sk_alloc(net, PF_KCM, GFP_KERNEL, &kcm_proto, kern);
1962 if (!sk)
1963 return -ENOMEM;
1964
1965 /* Allocate a kcm mux, shared between KCM sockets */
1966 mux = kmem_cache_zalloc(kcm_muxp, GFP_KERNEL);
1967 if (!mux) {
1968 sk_free(sk);
1969 return -ENOMEM;
1970 }
1971
1972 spin_lock_init(&mux->lock);
1973 spin_lock_init(&mux->rx_lock);
1974 INIT_LIST_HEAD(&mux->kcm_socks);
1975 INIT_LIST_HEAD(&mux->kcm_rx_waiters);
1976 INIT_LIST_HEAD(&mux->kcm_tx_waiters);
1977
1978 INIT_LIST_HEAD(&mux->psocks);
1979 INIT_LIST_HEAD(&mux->psocks_ready);
1980 INIT_LIST_HEAD(&mux->psocks_avail);
1981
1982 mux->knet = knet;
1983
1984 /* Add new MUX to list */
1985 mutex_lock(&knet->mutex);
1986 list_add_rcu(&mux->kcm_mux_list, &knet->mux_list);
1987 knet->count++;
1988 mutex_unlock(&knet->mutex);
1989
1990 skb_queue_head_init(&mux->rx_hold_queue);
1991
1992 /* Init KCM socket */
1993 sock_init_data(sock, sk);
1994 init_kcm_sock(kcm_sk(sk), mux);
1995
1996 return 0;
1997}
1998
1999static const struct net_proto_family kcm_family_ops = {
2000 .family = PF_KCM,
2001 .create = kcm_create,
2002 .owner = THIS_MODULE,
2003};
2004
2005static __net_init int kcm_init_net(struct net *net)
2006{
2007 struct kcm_net *knet = net_generic(net, kcm_net_id);
2008
2009 INIT_LIST_HEAD_RCU(&knet->mux_list);
2010 mutex_init(&knet->mutex);
2011
2012 return 0;
2013}
2014
2015static __net_exit void kcm_exit_net(struct net *net)
2016{
2017 struct kcm_net *knet = net_generic(net, kcm_net_id);
2018
2019 /* All KCM sockets should be closed at this point, which should mean
2020 * that all multiplexors and psocks have been destroyed.
2021 */
2022 WARN_ON(!list_empty(&knet->mux_list));
2023}
2024
2025static struct pernet_operations kcm_net_ops = {
2026 .init = kcm_init_net,
2027 .exit = kcm_exit_net,
2028 .id = &kcm_net_id,
2029 .size = sizeof(struct kcm_net),
2030};
2031
2032static int __init kcm_init(void)
2033{
2034 int err = -ENOMEM;
2035
2036 kcm_muxp = kmem_cache_create("kcm_mux_cache",
2037 sizeof(struct kcm_mux), 0,
2038 SLAB_HWCACHE_ALIGN, NULL);
2039 if (!kcm_muxp)
2040 goto fail;
2041
2042 kcm_psockp = kmem_cache_create("kcm_psock_cache",
2043 sizeof(struct kcm_psock), 0,
2044 SLAB_HWCACHE_ALIGN, NULL);
2045 if (!kcm_psockp)
2046 goto fail;
2047
2048 kcm_wq = create_singlethread_workqueue("kkcmd");
2049 if (!kcm_wq)
2050 goto fail;
2051
2052 err = proto_register(&kcm_proto, 1);
2053 if (err)
2054 goto fail;
2055
2056 err = register_pernet_device(&kcm_net_ops);
2057 if (err)
2058 goto net_ops_fail;
2059
2060 err = sock_register(&kcm_family_ops);
2061 if (err)
2062 goto sock_register_fail;
2063
2064 err = kcm_proc_init();
2065 if (err)
2066 goto proc_init_fail;
2067
2068 return 0;
2069
2070proc_init_fail:
2071 sock_unregister(PF_KCM);
2072
2073sock_register_fail:
2074 unregister_pernet_device(&kcm_net_ops);
2075
2076net_ops_fail:
2077 proto_unregister(&kcm_proto);
2078
2079fail:
2080 kmem_cache_destroy(kcm_muxp);
2081 kmem_cache_destroy(kcm_psockp);
2082
2083 if (kcm_wq)
2084 destroy_workqueue(kcm_wq);
2085
2086 return err;
2087}
2088
2089static void __exit kcm_exit(void)
2090{
2091 kcm_proc_exit();
2092 sock_unregister(PF_KCM);
2093 unregister_pernet_device(&kcm_net_ops);
2094 proto_unregister(&kcm_proto);
2095 destroy_workqueue(kcm_wq);
2096
2097 kmem_cache_destroy(kcm_muxp);
2098 kmem_cache_destroy(kcm_psockp);
2099}
2100
2101module_init(kcm_init);
2102module_exit(kcm_exit);
2103
2104MODULE_LICENSE("GPL");
2105MODULE_ALIAS_NETPROTO(PF_KCM);