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
kcm_sk(const struct sock * sk)39 static inline struct kcm_sock *kcm_sk(const struct sock *sk)
40 {
41 return (struct kcm_sock *)sk;
42 }
43
kcm_tx_msg(struct sk_buff * skb)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
report_csk_error(struct sock * csk,int err)49 static void report_csk_error(struct sock *csk, int err)
50 {
51 csk->sk_err = EPIPE;
52 sk_error_report(csk);
53 }
54
kcm_abort_tx_psock(struct kcm_psock * psock,int err,bool wakeup_kcm)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. */
kcm_update_rx_mux_stats(struct kcm_mux * mux,struct kcm_psock * psock)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
kcm_update_tx_mux_stats(struct kcm_mux * mux,struct kcm_psock * psock)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 */
kcm_rcv_ready(struct kcm_sock * kcm)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
kcm_rfree(struct sk_buff * skb)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
kcm_queue_rcv_skb(struct sock * sk,struct sk_buff * skb)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 */
requeue_rx_msgs(struct kcm_mux * mux,struct sk_buff_head * head)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 */
reserve_rx_kcm(struct kcm_psock * psock,struct sk_buff * head)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
kcm_done_work(struct work_struct * w)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 */
unreserve_rx_kcm(struct kcm_psock * psock,bool rcv_ready)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 */
psock_data_ready(struct sock * sk)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 */
kcm_rcv_strparser(struct strparser * strp,struct sk_buff * skb)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
kcm_parse_func_strparser(struct strparser * strp,struct sk_buff * skb)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
kcm_read_sock_done(struct strparser * strp,int err)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
psock_state_change(struct sock * sk)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
psock_write_space(struct sock * sk)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. */
reserve_psock(struct kcm_sock * kcm)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 */
psock_now_avail(struct kcm_psock * psock)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. */
unreserve_psock(struct kcm_sock * kcm)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
kcm_report_tx_retry(struct kcm_sock * kcm)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 */
kcm_write_msgs(struct kcm_sock * kcm)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
kcm_tx_work(struct work_struct * w)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
kcm_push(struct kcm_sock * kcm)741 static void kcm_push(struct kcm_sock *kcm)
742 {
743 if (kcm->tx_wait_more)
744 kcm_write_msgs(kcm);
745 }
746
kcm_sendmsg(struct socket * sock,struct msghdr * msg,size_t len)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 mutex_lock(&kcm->tx_mutex);
759 lock_sock(sk);
760
761 /* Per tcp_sendmsg this should be in poll */
762 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
763
764 if (sk->sk_err)
765 goto out_error;
766
767 if (kcm->seq_skb) {
768 /* Previously opened message */
769 head = kcm->seq_skb;
770 skb = kcm_tx_msg(head)->last_skb;
771 goto start;
772 }
773
774 /* Call the sk_stream functions to manage the sndbuf mem. */
775 if (!sk_stream_memory_free(sk)) {
776 kcm_push(kcm);
777 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
778 err = sk_stream_wait_memory(sk, &timeo);
779 if (err)
780 goto out_error;
781 }
782
783 if (msg_data_left(msg)) {
784 /* New message, alloc head skb */
785 head = alloc_skb(0, sk->sk_allocation);
786 while (!head) {
787 kcm_push(kcm);
788 err = sk_stream_wait_memory(sk, &timeo);
789 if (err)
790 goto out_error;
791
792 head = alloc_skb(0, sk->sk_allocation);
793 }
794
795 skb = head;
796
797 /* Set ip_summed to CHECKSUM_UNNECESSARY to avoid calling
798 * csum_and_copy_from_iter from skb_do_copy_data_nocache.
799 */
800 skb->ip_summed = CHECKSUM_UNNECESSARY;
801 }
802
803 start:
804 while (msg_data_left(msg)) {
805 bool merge = true;
806 int i = skb_shinfo(skb)->nr_frags;
807 struct page_frag *pfrag = sk_page_frag(sk);
808
809 if (!sk_page_frag_refill(sk, pfrag))
810 goto wait_for_memory;
811
812 if (!skb_can_coalesce(skb, i, pfrag->page,
813 pfrag->offset)) {
814 if (i == MAX_SKB_FRAGS) {
815 struct sk_buff *tskb;
816
817 tskb = alloc_skb(0, sk->sk_allocation);
818 if (!tskb)
819 goto wait_for_memory;
820
821 if (head == skb)
822 skb_shinfo(head)->frag_list = tskb;
823 else
824 skb->next = tskb;
825
826 skb = tskb;
827 skb->ip_summed = CHECKSUM_UNNECESSARY;
828 continue;
829 }
830 merge = false;
831 }
832
833 if (msg->msg_flags & MSG_SPLICE_PAGES) {
834 copy = msg_data_left(msg);
835 if (!sk_wmem_schedule(sk, copy))
836 goto wait_for_memory;
837
838 err = skb_splice_from_iter(skb, &msg->msg_iter, copy,
839 sk->sk_allocation);
840 if (err < 0) {
841 if (err == -EMSGSIZE)
842 goto wait_for_memory;
843 goto out_error;
844 }
845
846 copy = err;
847 skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
848 sk_wmem_queued_add(sk, copy);
849 sk_mem_charge(sk, copy);
850
851 if (head != skb)
852 head->truesize += copy;
853 } else {
854 copy = min_t(int, msg_data_left(msg),
855 pfrag->size - pfrag->offset);
856 if (!sk_wmem_schedule(sk, copy))
857 goto wait_for_memory;
858
859 err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
860 pfrag->page,
861 pfrag->offset,
862 copy);
863 if (err)
864 goto out_error;
865
866 /* Update the skb. */
867 if (merge) {
868 skb_frag_size_add(
869 &skb_shinfo(skb)->frags[i - 1], copy);
870 } else {
871 skb_fill_page_desc(skb, i, pfrag->page,
872 pfrag->offset, copy);
873 get_page(pfrag->page);
874 }
875
876 pfrag->offset += copy;
877 }
878
879 copied += copy;
880 if (head != skb) {
881 head->len += copy;
882 head->data_len += copy;
883 }
884
885 continue;
886
887 wait_for_memory:
888 kcm_push(kcm);
889 err = sk_stream_wait_memory(sk, &timeo);
890 if (err)
891 goto out_error;
892 }
893
894 if (eor) {
895 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
896
897 if (head) {
898 /* Message complete, queue it on send buffer */
899 __skb_queue_tail(&sk->sk_write_queue, head);
900 kcm->seq_skb = NULL;
901 KCM_STATS_INCR(kcm->stats.tx_msgs);
902 }
903
904 if (msg->msg_flags & MSG_BATCH) {
905 kcm->tx_wait_more = true;
906 } else if (kcm->tx_wait_more || not_busy) {
907 err = kcm_write_msgs(kcm);
908 if (err < 0) {
909 /* We got a hard error in write_msgs but have
910 * already queued this message. Report an error
911 * in the socket, but don't affect return value
912 * from sendmsg
913 */
914 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
915 report_csk_error(&kcm->sk, -err);
916 }
917 }
918 } else {
919 /* Message not complete, save state */
920 partial_message:
921 if (head) {
922 kcm->seq_skb = head;
923 kcm_tx_msg(head)->last_skb = skb;
924 }
925 }
926
927 KCM_STATS_ADD(kcm->stats.tx_bytes, copied);
928
929 release_sock(sk);
930 mutex_unlock(&kcm->tx_mutex);
931 return copied;
932
933 out_error:
934 kcm_push(kcm);
935
936 if (sock->type == SOCK_SEQPACKET) {
937 /* Wrote some bytes before encountering an
938 * error, return partial success.
939 */
940 if (copied)
941 goto partial_message;
942 if (head != kcm->seq_skb)
943 kfree_skb(head);
944 } else {
945 kfree_skb(head);
946 kcm->seq_skb = NULL;
947 }
948
949 err = sk_stream_error(sk, msg->msg_flags, err);
950
951 /* make sure we wake any epoll edge trigger waiter */
952 if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
953 sk->sk_write_space(sk);
954
955 release_sock(sk);
956 mutex_unlock(&kcm->tx_mutex);
957 return err;
958 }
959
kcm_splice_eof(struct socket * sock)960 static void kcm_splice_eof(struct socket *sock)
961 {
962 struct sock *sk = sock->sk;
963 struct kcm_sock *kcm = kcm_sk(sk);
964
965 if (skb_queue_empty_lockless(&sk->sk_write_queue))
966 return;
967
968 lock_sock(sk);
969 kcm_write_msgs(kcm);
970 release_sock(sk);
971 }
972
kcm_recvmsg(struct socket * sock,struct msghdr * msg,size_t len,int flags)973 static int kcm_recvmsg(struct socket *sock, struct msghdr *msg,
974 size_t len, int flags)
975 {
976 struct sock *sk = sock->sk;
977 struct kcm_sock *kcm = kcm_sk(sk);
978 int err = 0;
979 struct strp_msg *stm;
980 int copied = 0;
981 struct sk_buff *skb;
982
983 skb = skb_recv_datagram(sk, flags, &err);
984 if (!skb)
985 goto out;
986
987 /* Okay, have a message on the receive queue */
988
989 stm = strp_msg(skb);
990
991 if (len > stm->full_len)
992 len = stm->full_len;
993
994 err = skb_copy_datagram_msg(skb, stm->offset, msg, len);
995 if (err < 0)
996 goto out;
997
998 copied = len;
999 if (likely(!(flags & MSG_PEEK))) {
1000 KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1001 if (copied < stm->full_len) {
1002 if (sock->type == SOCK_DGRAM) {
1003 /* Truncated message */
1004 msg->msg_flags |= MSG_TRUNC;
1005 goto msg_finished;
1006 }
1007 stm->offset += copied;
1008 stm->full_len -= copied;
1009 } else {
1010 msg_finished:
1011 /* Finished with message */
1012 msg->msg_flags |= MSG_EOR;
1013 KCM_STATS_INCR(kcm->stats.rx_msgs);
1014 }
1015 }
1016
1017 out:
1018 skb_free_datagram(sk, skb);
1019 return copied ? : err;
1020 }
1021
kcm_splice_read(struct socket * sock,loff_t * ppos,struct pipe_inode_info * pipe,size_t len,unsigned int flags)1022 static ssize_t kcm_splice_read(struct socket *sock, loff_t *ppos,
1023 struct pipe_inode_info *pipe, size_t len,
1024 unsigned int flags)
1025 {
1026 struct sock *sk = sock->sk;
1027 struct kcm_sock *kcm = kcm_sk(sk);
1028 struct strp_msg *stm;
1029 int err = 0;
1030 ssize_t copied;
1031 struct sk_buff *skb;
1032
1033 /* Only support splice for SOCKSEQPACKET */
1034
1035 skb = skb_recv_datagram(sk, flags, &err);
1036 if (!skb)
1037 goto err_out;
1038
1039 /* Okay, have a message on the receive queue */
1040
1041 stm = strp_msg(skb);
1042
1043 if (len > stm->full_len)
1044 len = stm->full_len;
1045
1046 copied = skb_splice_bits(skb, sk, stm->offset, pipe, len, flags);
1047 if (copied < 0) {
1048 err = copied;
1049 goto err_out;
1050 }
1051
1052 KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1053
1054 stm->offset += copied;
1055 stm->full_len -= copied;
1056
1057 /* We have no way to return MSG_EOR. If all the bytes have been
1058 * read we still leave the message in the receive socket buffer.
1059 * A subsequent recvmsg needs to be done to return MSG_EOR and
1060 * finish reading the message.
1061 */
1062
1063 skb_free_datagram(sk, skb);
1064 return copied;
1065
1066 err_out:
1067 skb_free_datagram(sk, skb);
1068 return err;
1069 }
1070
1071 /* kcm sock lock held */
kcm_recv_disable(struct kcm_sock * kcm)1072 static void kcm_recv_disable(struct kcm_sock *kcm)
1073 {
1074 struct kcm_mux *mux = kcm->mux;
1075
1076 if (kcm->rx_disabled)
1077 return;
1078
1079 spin_lock_bh(&mux->rx_lock);
1080
1081 kcm->rx_disabled = 1;
1082
1083 /* If a psock is reserved we'll do cleanup in unreserve */
1084 if (!kcm->rx_psock) {
1085 if (kcm->rx_wait) {
1086 list_del(&kcm->wait_rx_list);
1087 /* paired with lockless reads in kcm_rfree() */
1088 WRITE_ONCE(kcm->rx_wait, false);
1089 }
1090
1091 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
1092 }
1093
1094 spin_unlock_bh(&mux->rx_lock);
1095 }
1096
1097 /* kcm sock lock held */
kcm_recv_enable(struct kcm_sock * kcm)1098 static void kcm_recv_enable(struct kcm_sock *kcm)
1099 {
1100 struct kcm_mux *mux = kcm->mux;
1101
1102 if (!kcm->rx_disabled)
1103 return;
1104
1105 spin_lock_bh(&mux->rx_lock);
1106
1107 kcm->rx_disabled = 0;
1108 kcm_rcv_ready(kcm);
1109
1110 spin_unlock_bh(&mux->rx_lock);
1111 }
1112
kcm_setsockopt(struct socket * sock,int level,int optname,sockptr_t optval,unsigned int optlen)1113 static int kcm_setsockopt(struct socket *sock, int level, int optname,
1114 sockptr_t optval, unsigned int optlen)
1115 {
1116 struct kcm_sock *kcm = kcm_sk(sock->sk);
1117 int val, valbool;
1118 int err = 0;
1119
1120 if (level != SOL_KCM)
1121 return -ENOPROTOOPT;
1122
1123 if (optlen < sizeof(int))
1124 return -EINVAL;
1125
1126 if (copy_from_sockptr(&val, optval, sizeof(int)))
1127 return -EFAULT;
1128
1129 valbool = val ? 1 : 0;
1130
1131 switch (optname) {
1132 case KCM_RECV_DISABLE:
1133 lock_sock(&kcm->sk);
1134 if (valbool)
1135 kcm_recv_disable(kcm);
1136 else
1137 kcm_recv_enable(kcm);
1138 release_sock(&kcm->sk);
1139 break;
1140 default:
1141 err = -ENOPROTOOPT;
1142 }
1143
1144 return err;
1145 }
1146
kcm_getsockopt(struct socket * sock,int level,int optname,char __user * optval,int __user * optlen)1147 static int kcm_getsockopt(struct socket *sock, int level, int optname,
1148 char __user *optval, int __user *optlen)
1149 {
1150 struct kcm_sock *kcm = kcm_sk(sock->sk);
1151 int val, len;
1152
1153 if (level != SOL_KCM)
1154 return -ENOPROTOOPT;
1155
1156 if (get_user(len, optlen))
1157 return -EFAULT;
1158
1159 if (len < 0)
1160 return -EINVAL;
1161
1162 len = min_t(unsigned int, len, sizeof(int));
1163
1164 switch (optname) {
1165 case KCM_RECV_DISABLE:
1166 val = kcm->rx_disabled;
1167 break;
1168 default:
1169 return -ENOPROTOOPT;
1170 }
1171
1172 if (put_user(len, optlen))
1173 return -EFAULT;
1174 if (copy_to_user(optval, &val, len))
1175 return -EFAULT;
1176 return 0;
1177 }
1178
init_kcm_sock(struct kcm_sock * kcm,struct kcm_mux * mux)1179 static void init_kcm_sock(struct kcm_sock *kcm, struct kcm_mux *mux)
1180 {
1181 struct kcm_sock *tkcm;
1182 struct list_head *head;
1183 int index = 0;
1184
1185 /* For SOCK_SEQPACKET sock type, datagram_poll checks the sk_state, so
1186 * we set sk_state, otherwise epoll_wait always returns right away with
1187 * EPOLLHUP
1188 */
1189 kcm->sk.sk_state = TCP_ESTABLISHED;
1190
1191 /* Add to mux's kcm sockets list */
1192 kcm->mux = mux;
1193 spin_lock_bh(&mux->lock);
1194
1195 head = &mux->kcm_socks;
1196 list_for_each_entry(tkcm, &mux->kcm_socks, kcm_sock_list) {
1197 if (tkcm->index != index)
1198 break;
1199 head = &tkcm->kcm_sock_list;
1200 index++;
1201 }
1202
1203 list_add(&kcm->kcm_sock_list, head);
1204 kcm->index = index;
1205
1206 mux->kcm_socks_cnt++;
1207 spin_unlock_bh(&mux->lock);
1208
1209 INIT_WORK(&kcm->tx_work, kcm_tx_work);
1210 mutex_init(&kcm->tx_mutex);
1211
1212 spin_lock_bh(&mux->rx_lock);
1213 kcm_rcv_ready(kcm);
1214 spin_unlock_bh(&mux->rx_lock);
1215 }
1216
kcm_attach(struct socket * sock,struct socket * csock,struct bpf_prog * prog)1217 static int kcm_attach(struct socket *sock, struct socket *csock,
1218 struct bpf_prog *prog)
1219 {
1220 struct kcm_sock *kcm = kcm_sk(sock->sk);
1221 struct kcm_mux *mux = kcm->mux;
1222 struct sock *csk;
1223 struct kcm_psock *psock = NULL, *tpsock;
1224 struct list_head *head;
1225 int index = 0;
1226 static const struct strp_callbacks cb = {
1227 .rcv_msg = kcm_rcv_strparser,
1228 .parse_msg = kcm_parse_func_strparser,
1229 .read_sock_done = kcm_read_sock_done,
1230 };
1231 int err = 0;
1232
1233 csk = csock->sk;
1234 if (!csk)
1235 return -EINVAL;
1236
1237 lock_sock(csk);
1238
1239 /* Only allow TCP sockets to be attached for now */
1240 if ((csk->sk_family != AF_INET && csk->sk_family != AF_INET6) ||
1241 csk->sk_protocol != IPPROTO_TCP) {
1242 err = -EOPNOTSUPP;
1243 goto out;
1244 }
1245
1246 /* Don't allow listeners or closed sockets */
1247 if (csk->sk_state == TCP_LISTEN || csk->sk_state == TCP_CLOSE) {
1248 err = -EOPNOTSUPP;
1249 goto out;
1250 }
1251
1252 psock = kmem_cache_zalloc(kcm_psockp, GFP_KERNEL);
1253 if (!psock) {
1254 err = -ENOMEM;
1255 goto out;
1256 }
1257
1258 psock->mux = mux;
1259 psock->sk = csk;
1260 psock->bpf_prog = prog;
1261
1262 write_lock_bh(&csk->sk_callback_lock);
1263
1264 /* Check if sk_user_data is already by KCM or someone else.
1265 * Must be done under lock to prevent race conditions.
1266 */
1267 if (csk->sk_user_data) {
1268 write_unlock_bh(&csk->sk_callback_lock);
1269 kmem_cache_free(kcm_psockp, psock);
1270 err = -EALREADY;
1271 goto out;
1272 }
1273
1274 err = strp_init(&psock->strp, csk, &cb);
1275 if (err) {
1276 write_unlock_bh(&csk->sk_callback_lock);
1277 kmem_cache_free(kcm_psockp, psock);
1278 goto out;
1279 }
1280
1281 psock->save_data_ready = csk->sk_data_ready;
1282 psock->save_write_space = csk->sk_write_space;
1283 psock->save_state_change = csk->sk_state_change;
1284 csk->sk_user_data = psock;
1285 csk->sk_data_ready = psock_data_ready;
1286 csk->sk_write_space = psock_write_space;
1287 csk->sk_state_change = psock_state_change;
1288
1289 write_unlock_bh(&csk->sk_callback_lock);
1290
1291 sock_hold(csk);
1292
1293 /* Finished initialization, now add the psock to the MUX. */
1294 spin_lock_bh(&mux->lock);
1295 head = &mux->psocks;
1296 list_for_each_entry(tpsock, &mux->psocks, psock_list) {
1297 if (tpsock->index != index)
1298 break;
1299 head = &tpsock->psock_list;
1300 index++;
1301 }
1302
1303 list_add(&psock->psock_list, head);
1304 psock->index = index;
1305
1306 KCM_STATS_INCR(mux->stats.psock_attach);
1307 mux->psocks_cnt++;
1308 psock_now_avail(psock);
1309 spin_unlock_bh(&mux->lock);
1310
1311 /* Schedule RX work in case there are already bytes queued */
1312 strp_check_rcv(&psock->strp);
1313
1314 out:
1315 release_sock(csk);
1316
1317 return err;
1318 }
1319
kcm_attach_ioctl(struct socket * sock,struct kcm_attach * info)1320 static int kcm_attach_ioctl(struct socket *sock, struct kcm_attach *info)
1321 {
1322 struct socket *csock;
1323 struct bpf_prog *prog;
1324 int err;
1325
1326 csock = sockfd_lookup(info->fd, &err);
1327 if (!csock)
1328 return -ENOENT;
1329
1330 prog = bpf_prog_get_type(info->bpf_fd, BPF_PROG_TYPE_SOCKET_FILTER);
1331 if (IS_ERR(prog)) {
1332 err = PTR_ERR(prog);
1333 goto out;
1334 }
1335
1336 err = kcm_attach(sock, csock, prog);
1337 if (err) {
1338 bpf_prog_put(prog);
1339 goto out;
1340 }
1341
1342 /* Keep reference on file also */
1343
1344 return 0;
1345 out:
1346 sockfd_put(csock);
1347 return err;
1348 }
1349
kcm_unattach(struct kcm_psock * psock)1350 static void kcm_unattach(struct kcm_psock *psock)
1351 {
1352 struct sock *csk = psock->sk;
1353 struct kcm_mux *mux = psock->mux;
1354
1355 lock_sock(csk);
1356
1357 /* Stop getting callbacks from TCP socket. After this there should
1358 * be no way to reserve a kcm for this psock.
1359 */
1360 write_lock_bh(&csk->sk_callback_lock);
1361 csk->sk_user_data = NULL;
1362 csk->sk_data_ready = psock->save_data_ready;
1363 csk->sk_write_space = psock->save_write_space;
1364 csk->sk_state_change = psock->save_state_change;
1365 strp_stop(&psock->strp);
1366
1367 if (WARN_ON(psock->rx_kcm)) {
1368 write_unlock_bh(&csk->sk_callback_lock);
1369 release_sock(csk);
1370 return;
1371 }
1372
1373 spin_lock_bh(&mux->rx_lock);
1374
1375 /* Stop receiver activities. After this point psock should not be
1376 * able to get onto ready list either through callbacks or work.
1377 */
1378 if (psock->ready_rx_msg) {
1379 list_del(&psock->psock_ready_list);
1380 kfree_skb(psock->ready_rx_msg);
1381 psock->ready_rx_msg = NULL;
1382 KCM_STATS_INCR(mux->stats.rx_ready_drops);
1383 }
1384
1385 spin_unlock_bh(&mux->rx_lock);
1386
1387 write_unlock_bh(&csk->sk_callback_lock);
1388
1389 /* Call strp_done without sock lock */
1390 release_sock(csk);
1391 strp_done(&psock->strp);
1392 lock_sock(csk);
1393
1394 bpf_prog_put(psock->bpf_prog);
1395
1396 spin_lock_bh(&mux->lock);
1397
1398 aggregate_psock_stats(&psock->stats, &mux->aggregate_psock_stats);
1399 save_strp_stats(&psock->strp, &mux->aggregate_strp_stats);
1400
1401 KCM_STATS_INCR(mux->stats.psock_unattach);
1402
1403 if (psock->tx_kcm) {
1404 /* psock was reserved. Just mark it finished and we will clean
1405 * up in the kcm paths, we need kcm lock which can not be
1406 * acquired here.
1407 */
1408 KCM_STATS_INCR(mux->stats.psock_unattach_rsvd);
1409 spin_unlock_bh(&mux->lock);
1410
1411 /* We are unattaching a socket that is reserved. Abort the
1412 * socket since we may be out of sync in sending on it. We need
1413 * to do this without the mux lock.
1414 */
1415 kcm_abort_tx_psock(psock, EPIPE, false);
1416
1417 spin_lock_bh(&mux->lock);
1418 if (!psock->tx_kcm) {
1419 /* psock now unreserved in window mux was unlocked */
1420 goto no_reserved;
1421 }
1422 psock->done = 1;
1423
1424 /* Commit done before queuing work to process it */
1425 smp_mb();
1426
1427 /* Queue tx work to make sure psock->done is handled */
1428 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
1429 spin_unlock_bh(&mux->lock);
1430 } else {
1431 no_reserved:
1432 if (!psock->tx_stopped)
1433 list_del(&psock->psock_avail_list);
1434 list_del(&psock->psock_list);
1435 mux->psocks_cnt--;
1436 spin_unlock_bh(&mux->lock);
1437
1438 sock_put(csk);
1439 fput(csk->sk_socket->file);
1440 kmem_cache_free(kcm_psockp, psock);
1441 }
1442
1443 release_sock(csk);
1444 }
1445
kcm_unattach_ioctl(struct socket * sock,struct kcm_unattach * info)1446 static int kcm_unattach_ioctl(struct socket *sock, struct kcm_unattach *info)
1447 {
1448 struct kcm_sock *kcm = kcm_sk(sock->sk);
1449 struct kcm_mux *mux = kcm->mux;
1450 struct kcm_psock *psock;
1451 struct socket *csock;
1452 struct sock *csk;
1453 int err;
1454
1455 csock = sockfd_lookup(info->fd, &err);
1456 if (!csock)
1457 return -ENOENT;
1458
1459 csk = csock->sk;
1460 if (!csk) {
1461 err = -EINVAL;
1462 goto out;
1463 }
1464
1465 err = -ENOENT;
1466
1467 spin_lock_bh(&mux->lock);
1468
1469 list_for_each_entry(psock, &mux->psocks, psock_list) {
1470 if (psock->sk != csk)
1471 continue;
1472
1473 /* Found the matching psock */
1474
1475 if (psock->unattaching || WARN_ON(psock->done)) {
1476 err = -EALREADY;
1477 break;
1478 }
1479
1480 psock->unattaching = 1;
1481
1482 spin_unlock_bh(&mux->lock);
1483
1484 /* Lower socket lock should already be held */
1485 kcm_unattach(psock);
1486
1487 err = 0;
1488 goto out;
1489 }
1490
1491 spin_unlock_bh(&mux->lock);
1492
1493 out:
1494 sockfd_put(csock);
1495 return err;
1496 }
1497
1498 static struct proto kcm_proto = {
1499 .name = "KCM",
1500 .owner = THIS_MODULE,
1501 .obj_size = sizeof(struct kcm_sock),
1502 };
1503
1504 /* Clone a kcm socket. */
kcm_clone(struct socket * osock)1505 static struct file *kcm_clone(struct socket *osock)
1506 {
1507 struct socket *newsock;
1508 struct sock *newsk;
1509
1510 newsock = sock_alloc();
1511 if (!newsock)
1512 return ERR_PTR(-ENFILE);
1513
1514 newsock->type = osock->type;
1515 newsock->ops = osock->ops;
1516
1517 __module_get(newsock->ops->owner);
1518
1519 newsk = sk_alloc(sock_net(osock->sk), PF_KCM, GFP_KERNEL,
1520 &kcm_proto, false);
1521 if (!newsk) {
1522 sock_release(newsock);
1523 return ERR_PTR(-ENOMEM);
1524 }
1525 sock_init_data(newsock, newsk);
1526 init_kcm_sock(kcm_sk(newsk), kcm_sk(osock->sk)->mux);
1527
1528 return sock_alloc_file(newsock, 0, osock->sk->sk_prot_creator->name);
1529 }
1530
kcm_ioctl(struct socket * sock,unsigned int cmd,unsigned long arg)1531 static int kcm_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
1532 {
1533 int err;
1534
1535 switch (cmd) {
1536 case SIOCKCMATTACH: {
1537 struct kcm_attach info;
1538
1539 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1540 return -EFAULT;
1541
1542 err = kcm_attach_ioctl(sock, &info);
1543
1544 break;
1545 }
1546 case SIOCKCMUNATTACH: {
1547 struct kcm_unattach info;
1548
1549 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1550 return -EFAULT;
1551
1552 err = kcm_unattach_ioctl(sock, &info);
1553
1554 break;
1555 }
1556 case SIOCKCMCLONE: {
1557 struct kcm_clone info;
1558 struct file *file;
1559
1560 info.fd = get_unused_fd_flags(0);
1561 if (unlikely(info.fd < 0))
1562 return info.fd;
1563
1564 file = kcm_clone(sock);
1565 if (IS_ERR(file)) {
1566 put_unused_fd(info.fd);
1567 return PTR_ERR(file);
1568 }
1569 if (copy_to_user((void __user *)arg, &info,
1570 sizeof(info))) {
1571 put_unused_fd(info.fd);
1572 fput(file);
1573 return -EFAULT;
1574 }
1575 fd_install(info.fd, file);
1576 err = 0;
1577 break;
1578 }
1579 default:
1580 err = -ENOIOCTLCMD;
1581 break;
1582 }
1583
1584 return err;
1585 }
1586
free_mux(struct rcu_head * rcu)1587 static void free_mux(struct rcu_head *rcu)
1588 {
1589 struct kcm_mux *mux = container_of(rcu,
1590 struct kcm_mux, rcu);
1591
1592 kmem_cache_free(kcm_muxp, mux);
1593 }
1594
release_mux(struct kcm_mux * mux)1595 static void release_mux(struct kcm_mux *mux)
1596 {
1597 struct kcm_net *knet = mux->knet;
1598 struct kcm_psock *psock, *tmp_psock;
1599
1600 /* Release psocks */
1601 list_for_each_entry_safe(psock, tmp_psock,
1602 &mux->psocks, psock_list) {
1603 if (!WARN_ON(psock->unattaching))
1604 kcm_unattach(psock);
1605 }
1606
1607 if (WARN_ON(mux->psocks_cnt))
1608 return;
1609
1610 __skb_queue_purge(&mux->rx_hold_queue);
1611
1612 mutex_lock(&knet->mutex);
1613 aggregate_mux_stats(&mux->stats, &knet->aggregate_mux_stats);
1614 aggregate_psock_stats(&mux->aggregate_psock_stats,
1615 &knet->aggregate_psock_stats);
1616 aggregate_strp_stats(&mux->aggregate_strp_stats,
1617 &knet->aggregate_strp_stats);
1618 list_del_rcu(&mux->kcm_mux_list);
1619 knet->count--;
1620 mutex_unlock(&knet->mutex);
1621
1622 call_rcu(&mux->rcu, free_mux);
1623 }
1624
kcm_done(struct kcm_sock * kcm)1625 static void kcm_done(struct kcm_sock *kcm)
1626 {
1627 struct kcm_mux *mux = kcm->mux;
1628 struct sock *sk = &kcm->sk;
1629 int socks_cnt;
1630
1631 spin_lock_bh(&mux->rx_lock);
1632 if (kcm->rx_psock) {
1633 /* Cleanup in unreserve_rx_kcm */
1634 WARN_ON(kcm->done);
1635 kcm->rx_disabled = 1;
1636 kcm->done = 1;
1637 spin_unlock_bh(&mux->rx_lock);
1638 return;
1639 }
1640
1641 if (kcm->rx_wait) {
1642 list_del(&kcm->wait_rx_list);
1643 /* paired with lockless reads in kcm_rfree() */
1644 WRITE_ONCE(kcm->rx_wait, false);
1645 }
1646 /* Move any pending receive messages to other kcm sockets */
1647 requeue_rx_msgs(mux, &sk->sk_receive_queue);
1648
1649 spin_unlock_bh(&mux->rx_lock);
1650
1651 if (WARN_ON(sk_rmem_alloc_get(sk)))
1652 return;
1653
1654 /* Detach from MUX */
1655 spin_lock_bh(&mux->lock);
1656
1657 list_del(&kcm->kcm_sock_list);
1658 mux->kcm_socks_cnt--;
1659 socks_cnt = mux->kcm_socks_cnt;
1660
1661 spin_unlock_bh(&mux->lock);
1662
1663 if (!socks_cnt) {
1664 /* We are done with the mux now. */
1665 release_mux(mux);
1666 }
1667
1668 WARN_ON(kcm->rx_wait);
1669
1670 sock_put(&kcm->sk);
1671 }
1672
1673 /* Called by kcm_release to close a KCM socket.
1674 * If this is the last KCM socket on the MUX, destroy the MUX.
1675 */
kcm_release(struct socket * sock)1676 static int kcm_release(struct socket *sock)
1677 {
1678 struct sock *sk = sock->sk;
1679 struct kcm_sock *kcm;
1680 struct kcm_mux *mux;
1681 struct kcm_psock *psock;
1682
1683 if (!sk)
1684 return 0;
1685
1686 kcm = kcm_sk(sk);
1687 mux = kcm->mux;
1688
1689 lock_sock(sk);
1690 sock_orphan(sk);
1691 kfree_skb(kcm->seq_skb);
1692
1693 /* Purge queue under lock to avoid race condition with tx_work trying
1694 * to act when queue is nonempty. If tx_work runs after this point
1695 * it will just return.
1696 */
1697 __skb_queue_purge(&sk->sk_write_queue);
1698
1699 /* Set tx_stopped. This is checked when psock is bound to a kcm and we
1700 * get a writespace callback. This prevents further work being queued
1701 * from the callback (unbinding the psock occurs after canceling work.
1702 */
1703 kcm->tx_stopped = 1;
1704
1705 release_sock(sk);
1706
1707 spin_lock_bh(&mux->lock);
1708 if (kcm->tx_wait) {
1709 /* Take of tx_wait list, after this point there should be no way
1710 * that a psock will be assigned to this kcm.
1711 */
1712 list_del(&kcm->wait_psock_list);
1713 kcm->tx_wait = false;
1714 }
1715 spin_unlock_bh(&mux->lock);
1716
1717 /* Cancel work. After this point there should be no outside references
1718 * to the kcm socket.
1719 */
1720 cancel_work_sync(&kcm->tx_work);
1721
1722 lock_sock(sk);
1723 psock = kcm->tx_psock;
1724 if (psock) {
1725 /* A psock was reserved, so we need to kill it since it
1726 * may already have some bytes queued from a message. We
1727 * need to do this after removing kcm from tx_wait list.
1728 */
1729 kcm_abort_tx_psock(psock, EPIPE, false);
1730 unreserve_psock(kcm);
1731 }
1732 release_sock(sk);
1733
1734 WARN_ON(kcm->tx_wait);
1735 WARN_ON(kcm->tx_psock);
1736
1737 sock->sk = NULL;
1738
1739 kcm_done(kcm);
1740
1741 return 0;
1742 }
1743
1744 static const struct proto_ops kcm_dgram_ops = {
1745 .family = PF_KCM,
1746 .owner = THIS_MODULE,
1747 .release = kcm_release,
1748 .bind = sock_no_bind,
1749 .connect = sock_no_connect,
1750 .socketpair = sock_no_socketpair,
1751 .accept = sock_no_accept,
1752 .getname = sock_no_getname,
1753 .poll = datagram_poll,
1754 .ioctl = kcm_ioctl,
1755 .listen = sock_no_listen,
1756 .shutdown = sock_no_shutdown,
1757 .setsockopt = kcm_setsockopt,
1758 .getsockopt = kcm_getsockopt,
1759 .sendmsg = kcm_sendmsg,
1760 .recvmsg = kcm_recvmsg,
1761 .mmap = sock_no_mmap,
1762 .splice_eof = kcm_splice_eof,
1763 };
1764
1765 static const struct proto_ops kcm_seqpacket_ops = {
1766 .family = PF_KCM,
1767 .owner = THIS_MODULE,
1768 .release = kcm_release,
1769 .bind = sock_no_bind,
1770 .connect = sock_no_connect,
1771 .socketpair = sock_no_socketpair,
1772 .accept = sock_no_accept,
1773 .getname = sock_no_getname,
1774 .poll = datagram_poll,
1775 .ioctl = kcm_ioctl,
1776 .listen = sock_no_listen,
1777 .shutdown = sock_no_shutdown,
1778 .setsockopt = kcm_setsockopt,
1779 .getsockopt = kcm_getsockopt,
1780 .sendmsg = kcm_sendmsg,
1781 .recvmsg = kcm_recvmsg,
1782 .mmap = sock_no_mmap,
1783 .splice_eof = kcm_splice_eof,
1784 .splice_read = kcm_splice_read,
1785 };
1786
1787 /* Create proto operation for kcm sockets */
kcm_create(struct net * net,struct socket * sock,int protocol,int kern)1788 static int kcm_create(struct net *net, struct socket *sock,
1789 int protocol, int kern)
1790 {
1791 struct kcm_net *knet = net_generic(net, kcm_net_id);
1792 struct sock *sk;
1793 struct kcm_mux *mux;
1794
1795 switch (sock->type) {
1796 case SOCK_DGRAM:
1797 sock->ops = &kcm_dgram_ops;
1798 break;
1799 case SOCK_SEQPACKET:
1800 sock->ops = &kcm_seqpacket_ops;
1801 break;
1802 default:
1803 return -ESOCKTNOSUPPORT;
1804 }
1805
1806 if (protocol != KCMPROTO_CONNECTED)
1807 return -EPROTONOSUPPORT;
1808
1809 sk = sk_alloc(net, PF_KCM, GFP_KERNEL, &kcm_proto, kern);
1810 if (!sk)
1811 return -ENOMEM;
1812
1813 /* Allocate a kcm mux, shared between KCM sockets */
1814 mux = kmem_cache_zalloc(kcm_muxp, GFP_KERNEL);
1815 if (!mux) {
1816 sk_free(sk);
1817 return -ENOMEM;
1818 }
1819
1820 spin_lock_init(&mux->lock);
1821 spin_lock_init(&mux->rx_lock);
1822 INIT_LIST_HEAD(&mux->kcm_socks);
1823 INIT_LIST_HEAD(&mux->kcm_rx_waiters);
1824 INIT_LIST_HEAD(&mux->kcm_tx_waiters);
1825
1826 INIT_LIST_HEAD(&mux->psocks);
1827 INIT_LIST_HEAD(&mux->psocks_ready);
1828 INIT_LIST_HEAD(&mux->psocks_avail);
1829
1830 mux->knet = knet;
1831
1832 /* Add new MUX to list */
1833 mutex_lock(&knet->mutex);
1834 list_add_rcu(&mux->kcm_mux_list, &knet->mux_list);
1835 knet->count++;
1836 mutex_unlock(&knet->mutex);
1837
1838 skb_queue_head_init(&mux->rx_hold_queue);
1839
1840 /* Init KCM socket */
1841 sock_init_data(sock, sk);
1842 init_kcm_sock(kcm_sk(sk), mux);
1843
1844 return 0;
1845 }
1846
1847 static const struct net_proto_family kcm_family_ops = {
1848 .family = PF_KCM,
1849 .create = kcm_create,
1850 .owner = THIS_MODULE,
1851 };
1852
kcm_init_net(struct net * net)1853 static __net_init int kcm_init_net(struct net *net)
1854 {
1855 struct kcm_net *knet = net_generic(net, kcm_net_id);
1856
1857 INIT_LIST_HEAD_RCU(&knet->mux_list);
1858 mutex_init(&knet->mutex);
1859
1860 return 0;
1861 }
1862
kcm_exit_net(struct net * net)1863 static __net_exit void kcm_exit_net(struct net *net)
1864 {
1865 struct kcm_net *knet = net_generic(net, kcm_net_id);
1866
1867 /* All KCM sockets should be closed at this point, which should mean
1868 * that all multiplexors and psocks have been destroyed.
1869 */
1870 WARN_ON(!list_empty(&knet->mux_list));
1871
1872 mutex_destroy(&knet->mutex);
1873 }
1874
1875 static struct pernet_operations kcm_net_ops = {
1876 .init = kcm_init_net,
1877 .exit = kcm_exit_net,
1878 .id = &kcm_net_id,
1879 .size = sizeof(struct kcm_net),
1880 };
1881
kcm_init(void)1882 static int __init kcm_init(void)
1883 {
1884 int err = -ENOMEM;
1885
1886 kcm_muxp = KMEM_CACHE(kcm_mux, SLAB_HWCACHE_ALIGN);
1887 if (!kcm_muxp)
1888 goto fail;
1889
1890 kcm_psockp = KMEM_CACHE(kcm_psock, SLAB_HWCACHE_ALIGN);
1891 if (!kcm_psockp)
1892 goto fail;
1893
1894 kcm_wq = create_singlethread_workqueue("kkcmd");
1895 if (!kcm_wq)
1896 goto fail;
1897
1898 err = proto_register(&kcm_proto, 1);
1899 if (err)
1900 goto fail;
1901
1902 err = register_pernet_device(&kcm_net_ops);
1903 if (err)
1904 goto net_ops_fail;
1905
1906 err = sock_register(&kcm_family_ops);
1907 if (err)
1908 goto sock_register_fail;
1909
1910 err = kcm_proc_init();
1911 if (err)
1912 goto proc_init_fail;
1913
1914 return 0;
1915
1916 proc_init_fail:
1917 sock_unregister(PF_KCM);
1918
1919 sock_register_fail:
1920 unregister_pernet_device(&kcm_net_ops);
1921
1922 net_ops_fail:
1923 proto_unregister(&kcm_proto);
1924
1925 fail:
1926 kmem_cache_destroy(kcm_muxp);
1927 kmem_cache_destroy(kcm_psockp);
1928
1929 if (kcm_wq)
1930 destroy_workqueue(kcm_wq);
1931
1932 return err;
1933 }
1934
kcm_exit(void)1935 static void __exit kcm_exit(void)
1936 {
1937 kcm_proc_exit();
1938 sock_unregister(PF_KCM);
1939 unregister_pernet_device(&kcm_net_ops);
1940 proto_unregister(&kcm_proto);
1941 destroy_workqueue(kcm_wq);
1942
1943 kmem_cache_destroy(kcm_muxp);
1944 kmem_cache_destroy(kcm_psockp);
1945 }
1946
1947 module_init(kcm_init);
1948 module_exit(kcm_exit);
1949
1950 MODULE_LICENSE("GPL");
1951 MODULE_DESCRIPTION("KCM (Kernel Connection Multiplexor) sockets");
1952 MODULE_ALIAS_NETPROTO(PF_KCM);
1953