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