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