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