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_ONCE(!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, *frag_prev = 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 frag_prev = skb;
828 skb = tskb;
829 skb->ip_summed = CHECKSUM_UNNECESSARY;
830 continue;
831 }
832 merge = false;
833 }
834
835 if (msg->msg_flags & MSG_SPLICE_PAGES) {
836 copy = msg_data_left(msg);
837 if (!sk_wmem_schedule(sk, copy))
838 goto wait_for_memory;
839
840 err = skb_splice_from_iter(skb, &msg->msg_iter, copy);
841 if (err < 0) {
842 if (err == -EMSGSIZE)
843 goto wait_for_memory;
844 goto out_error;
845 }
846
847 copy = err;
848 skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
849 sk_wmem_queued_add(sk, copy);
850 sk_mem_charge(sk, copy);
851
852 if (head != skb)
853 head->truesize += copy;
854 } else {
855 copy = min_t(int, msg_data_left(msg),
856 pfrag->size - pfrag->offset);
857 if (!sk_wmem_schedule(sk, copy))
858 goto wait_for_memory;
859
860 err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
861 pfrag->page,
862 pfrag->offset,
863 copy);
864 if (err)
865 goto out_error;
866
867 /* Update the skb. */
868 if (merge) {
869 skb_frag_size_add(
870 &skb_shinfo(skb)->frags[i - 1], copy);
871 } else {
872 skb_fill_page_desc(skb, i, pfrag->page,
873 pfrag->offset, copy);
874 get_page(pfrag->page);
875 }
876
877 pfrag->offset += copy;
878 }
879
880 copied += copy;
881 if (head != skb) {
882 head->len += copy;
883 head->data_len += copy;
884 }
885
886 continue;
887
888 wait_for_memory:
889 kcm_push(kcm);
890 err = sk_stream_wait_memory(sk, &timeo);
891 if (err)
892 goto out_error;
893 }
894
895 if (eor) {
896 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
897
898 if (head) {
899 /* Message complete, queue it on send buffer */
900 __skb_queue_tail(&sk->sk_write_queue, head);
901 kcm->seq_skb = NULL;
902 KCM_STATS_INCR(kcm->stats.tx_msgs);
903 }
904
905 if (msg->msg_flags & MSG_BATCH) {
906 kcm->tx_wait_more = true;
907 } else if (kcm->tx_wait_more || not_busy) {
908 err = kcm_write_msgs(kcm);
909 if (err < 0) {
910 /* We got a hard error in write_msgs but have
911 * already queued this message. Report an error
912 * in the socket, but don't affect return value
913 * from sendmsg
914 */
915 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
916 report_csk_error(&kcm->sk, -err);
917 }
918 }
919 } else {
920 /* Message not complete, save state */
921 partial_message:
922 if (head) {
923 kcm->seq_skb = head;
924 kcm_tx_msg(head)->last_skb = skb;
925 }
926 }
927
928 KCM_STATS_ADD(kcm->stats.tx_bytes, copied);
929
930 release_sock(sk);
931 mutex_unlock(&kcm->tx_mutex);
932 return copied;
933
934 out_error:
935 kcm_push(kcm);
936
937 /* When MAX_SKB_FRAGS was reached, a new skb was allocated and
938 * linked into the frag_list before data copy. If the copy
939 * subsequently failed, this skb has zero frags. Remove it from
940 * the frag_list to prevent kcm_write_msgs from later hitting
941 * WARN_ON(!skb_shinfo(skb)->nr_frags).
942 */
943 if (frag_prev && !skb_shinfo(skb)->nr_frags) {
944 if (head == frag_prev)
945 skb_shinfo(head)->frag_list = NULL;
946 else
947 frag_prev->next = NULL;
948 kfree_skb(skb);
949 /* Update skb as it may be saved in partial_message via goto */
950 skb = frag_prev;
951 }
952
953 if (sock->type == SOCK_SEQPACKET) {
954 /* Wrote some bytes before encountering an
955 * error, return partial success.
956 */
957 if (copied)
958 goto partial_message;
959 if (head != kcm->seq_skb)
960 kfree_skb(head);
961 } else {
962 kfree_skb(head);
963 kcm->seq_skb = NULL;
964 }
965
966 err = sk_stream_error(sk, msg->msg_flags, err);
967
968 /* make sure we wake any epoll edge trigger waiter */
969 if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
970 sk->sk_write_space(sk);
971
972 release_sock(sk);
973 mutex_unlock(&kcm->tx_mutex);
974 return err;
975 }
976
kcm_splice_eof(struct socket * sock)977 static void kcm_splice_eof(struct socket *sock)
978 {
979 struct sock *sk = sock->sk;
980 struct kcm_sock *kcm = kcm_sk(sk);
981
982 if (skb_queue_empty_lockless(&sk->sk_write_queue))
983 return;
984
985 lock_sock(sk);
986 kcm_write_msgs(kcm);
987 release_sock(sk);
988 }
989
kcm_recvmsg(struct socket * sock,struct msghdr * msg,size_t len,int flags)990 static int kcm_recvmsg(struct socket *sock, struct msghdr *msg,
991 size_t len, int flags)
992 {
993 struct sock *sk = sock->sk;
994 struct kcm_sock *kcm = kcm_sk(sk);
995 int err = 0;
996 struct strp_msg *stm;
997 int copied = 0;
998 struct sk_buff *skb;
999
1000 skb = skb_recv_datagram(sk, flags, &err);
1001 if (!skb)
1002 goto out;
1003
1004 /* Okay, have a message on the receive queue */
1005
1006 stm = strp_msg(skb);
1007
1008 if (len > stm->full_len)
1009 len = stm->full_len;
1010
1011 err = skb_copy_datagram_msg(skb, stm->offset, msg, len);
1012 if (err < 0)
1013 goto out;
1014
1015 copied = len;
1016 if (likely(!(flags & MSG_PEEK))) {
1017 KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1018 if (copied < stm->full_len) {
1019 if (sock->type == SOCK_DGRAM) {
1020 /* Truncated message */
1021 msg->msg_flags |= MSG_TRUNC;
1022 goto msg_finished;
1023 }
1024 stm->offset += copied;
1025 stm->full_len -= copied;
1026 } else {
1027 msg_finished:
1028 /* Finished with message */
1029 msg->msg_flags |= MSG_EOR;
1030 KCM_STATS_INCR(kcm->stats.rx_msgs);
1031 }
1032 }
1033
1034 out:
1035 skb_free_datagram(sk, skb);
1036 return copied ? : err;
1037 }
1038
kcm_splice_read(struct socket * sock,loff_t * ppos,struct pipe_inode_info * pipe,size_t len,unsigned int flags)1039 static ssize_t kcm_splice_read(struct socket *sock, loff_t *ppos,
1040 struct pipe_inode_info *pipe, size_t len,
1041 unsigned int flags)
1042 {
1043 struct sock *sk = sock->sk;
1044 struct kcm_sock *kcm = kcm_sk(sk);
1045 struct strp_msg *stm;
1046 int err = 0;
1047 ssize_t copied;
1048 struct sk_buff *skb;
1049
1050 if (sock->file->f_flags & O_NONBLOCK || flags & SPLICE_F_NONBLOCK)
1051 flags = MSG_DONTWAIT;
1052 else
1053 flags = 0;
1054
1055 /* Only support splice for SOCKSEQPACKET */
1056
1057 skb = skb_recv_datagram(sk, flags, &err);
1058 if (!skb)
1059 goto err_out;
1060
1061 /* Okay, have a message on the receive queue */
1062
1063 stm = strp_msg(skb);
1064
1065 if (len > stm->full_len)
1066 len = stm->full_len;
1067
1068 copied = skb_splice_bits(skb, sk, stm->offset, pipe, len, flags);
1069 if (copied < 0) {
1070 err = copied;
1071 goto err_out;
1072 }
1073
1074 KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1075
1076 stm->offset += copied;
1077 stm->full_len -= copied;
1078
1079 /* We have no way to return MSG_EOR. If all the bytes have been
1080 * read we still leave the message in the receive socket buffer.
1081 * A subsequent recvmsg needs to be done to return MSG_EOR and
1082 * finish reading the message.
1083 */
1084
1085 skb_free_datagram(sk, skb);
1086 return copied;
1087
1088 err_out:
1089 skb_free_datagram(sk, skb);
1090 return err;
1091 }
1092
1093 /* kcm sock lock held */
kcm_recv_disable(struct kcm_sock * kcm)1094 static void kcm_recv_disable(struct kcm_sock *kcm)
1095 {
1096 struct kcm_mux *mux = kcm->mux;
1097
1098 if (kcm->rx_disabled)
1099 return;
1100
1101 spin_lock_bh(&mux->rx_lock);
1102
1103 kcm->rx_disabled = 1;
1104
1105 /* If a psock is reserved we'll do cleanup in unreserve */
1106 if (!kcm->rx_psock) {
1107 if (kcm->rx_wait) {
1108 list_del(&kcm->wait_rx_list);
1109 /* paired with lockless reads in kcm_rfree() */
1110 WRITE_ONCE(kcm->rx_wait, false);
1111 }
1112
1113 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
1114 }
1115
1116 spin_unlock_bh(&mux->rx_lock);
1117 }
1118
1119 /* kcm sock lock held */
kcm_recv_enable(struct kcm_sock * kcm)1120 static void kcm_recv_enable(struct kcm_sock *kcm)
1121 {
1122 struct kcm_mux *mux = kcm->mux;
1123
1124 if (!kcm->rx_disabled)
1125 return;
1126
1127 spin_lock_bh(&mux->rx_lock);
1128
1129 kcm->rx_disabled = 0;
1130 kcm_rcv_ready(kcm);
1131
1132 spin_unlock_bh(&mux->rx_lock);
1133 }
1134
kcm_setsockopt(struct socket * sock,int level,int optname,sockptr_t optval,unsigned int optlen)1135 static int kcm_setsockopt(struct socket *sock, int level, int optname,
1136 sockptr_t optval, unsigned int optlen)
1137 {
1138 struct kcm_sock *kcm = kcm_sk(sock->sk);
1139 int val, valbool;
1140 int err = 0;
1141
1142 if (level != SOL_KCM)
1143 return -ENOPROTOOPT;
1144
1145 if (optlen < sizeof(int))
1146 return -EINVAL;
1147
1148 if (copy_from_sockptr(&val, optval, sizeof(int)))
1149 return -EFAULT;
1150
1151 valbool = val ? 1 : 0;
1152
1153 switch (optname) {
1154 case KCM_RECV_DISABLE:
1155 lock_sock(&kcm->sk);
1156 if (valbool)
1157 kcm_recv_disable(kcm);
1158 else
1159 kcm_recv_enable(kcm);
1160 release_sock(&kcm->sk);
1161 break;
1162 default:
1163 err = -ENOPROTOOPT;
1164 }
1165
1166 return err;
1167 }
1168
kcm_getsockopt(struct socket * sock,int level,int optname,char __user * optval,int __user * optlen)1169 static int kcm_getsockopt(struct socket *sock, int level, int optname,
1170 char __user *optval, int __user *optlen)
1171 {
1172 struct kcm_sock *kcm = kcm_sk(sock->sk);
1173 int val, len;
1174
1175 if (level != SOL_KCM)
1176 return -ENOPROTOOPT;
1177
1178 if (get_user(len, optlen))
1179 return -EFAULT;
1180
1181 if (len < 0)
1182 return -EINVAL;
1183
1184 len = min_t(unsigned int, len, sizeof(int));
1185
1186 switch (optname) {
1187 case KCM_RECV_DISABLE:
1188 val = kcm->rx_disabled;
1189 break;
1190 default:
1191 return -ENOPROTOOPT;
1192 }
1193
1194 if (put_user(len, optlen))
1195 return -EFAULT;
1196 if (copy_to_user(optval, &val, len))
1197 return -EFAULT;
1198 return 0;
1199 }
1200
init_kcm_sock(struct kcm_sock * kcm,struct kcm_mux * mux)1201 static void init_kcm_sock(struct kcm_sock *kcm, struct kcm_mux *mux)
1202 {
1203 struct kcm_sock *tkcm;
1204 struct list_head *head;
1205 int index = 0;
1206
1207 /* For SOCK_SEQPACKET sock type, datagram_poll checks the sk_state, so
1208 * we set sk_state, otherwise epoll_wait always returns right away with
1209 * EPOLLHUP
1210 */
1211 kcm->sk.sk_state = TCP_ESTABLISHED;
1212
1213 /* Add to mux's kcm sockets list */
1214 kcm->mux = mux;
1215 spin_lock_bh(&mux->lock);
1216
1217 head = &mux->kcm_socks;
1218 list_for_each_entry(tkcm, &mux->kcm_socks, kcm_sock_list) {
1219 if (tkcm->index != index)
1220 break;
1221 head = &tkcm->kcm_sock_list;
1222 index++;
1223 }
1224
1225 list_add(&kcm->kcm_sock_list, head);
1226 kcm->index = index;
1227
1228 mux->kcm_socks_cnt++;
1229 spin_unlock_bh(&mux->lock);
1230
1231 INIT_WORK(&kcm->tx_work, kcm_tx_work);
1232 mutex_init(&kcm->tx_mutex);
1233
1234 spin_lock_bh(&mux->rx_lock);
1235 kcm_rcv_ready(kcm);
1236 spin_unlock_bh(&mux->rx_lock);
1237 }
1238
kcm_attach(struct socket * sock,struct socket * csock,struct bpf_prog * prog)1239 static int kcm_attach(struct socket *sock, struct socket *csock,
1240 struct bpf_prog *prog)
1241 {
1242 struct kcm_sock *kcm = kcm_sk(sock->sk);
1243 struct kcm_mux *mux = kcm->mux;
1244 struct sock *csk;
1245 struct kcm_psock *psock = NULL, *tpsock;
1246 struct list_head *head;
1247 int index = 0;
1248 static const struct strp_callbacks cb = {
1249 .rcv_msg = kcm_rcv_strparser,
1250 .parse_msg = kcm_parse_func_strparser,
1251 .read_sock_done = kcm_read_sock_done,
1252 };
1253 int err = 0;
1254
1255 csk = csock->sk;
1256 if (!csk)
1257 return -EINVAL;
1258
1259 lock_sock(csk);
1260
1261 /* Only allow TCP sockets to be attached for now */
1262 if ((csk->sk_family != AF_INET && csk->sk_family != AF_INET6) ||
1263 csk->sk_protocol != IPPROTO_TCP) {
1264 err = -EOPNOTSUPP;
1265 goto out;
1266 }
1267
1268 /* Don't allow listeners or closed sockets */
1269 if (csk->sk_state == TCP_LISTEN || csk->sk_state == TCP_CLOSE) {
1270 err = -EOPNOTSUPP;
1271 goto out;
1272 }
1273
1274 psock = kmem_cache_zalloc(kcm_psockp, GFP_KERNEL);
1275 if (!psock) {
1276 err = -ENOMEM;
1277 goto out;
1278 }
1279
1280 psock->mux = mux;
1281 psock->sk = csk;
1282 psock->bpf_prog = prog;
1283
1284 write_lock_bh(&csk->sk_callback_lock);
1285
1286 /* Check if sk_user_data is already by KCM or someone else.
1287 * Must be done under lock to prevent race conditions.
1288 */
1289 if (csk->sk_user_data) {
1290 write_unlock_bh(&csk->sk_callback_lock);
1291 kmem_cache_free(kcm_psockp, psock);
1292 err = -EALREADY;
1293 goto out;
1294 }
1295
1296 err = strp_init(&psock->strp, csk, &cb);
1297 if (err) {
1298 write_unlock_bh(&csk->sk_callback_lock);
1299 kmem_cache_free(kcm_psockp, psock);
1300 goto out;
1301 }
1302
1303 psock->save_data_ready = csk->sk_data_ready;
1304 psock->save_write_space = csk->sk_write_space;
1305 psock->save_state_change = csk->sk_state_change;
1306 csk->sk_user_data = psock;
1307 csk->sk_data_ready = psock_data_ready;
1308 csk->sk_write_space = psock_write_space;
1309 csk->sk_state_change = psock_state_change;
1310
1311 write_unlock_bh(&csk->sk_callback_lock);
1312
1313 sock_hold(csk);
1314
1315 /* Finished initialization, now add the psock to the MUX. */
1316 spin_lock_bh(&mux->lock);
1317 head = &mux->psocks;
1318 list_for_each_entry(tpsock, &mux->psocks, psock_list) {
1319 if (tpsock->index != index)
1320 break;
1321 head = &tpsock->psock_list;
1322 index++;
1323 }
1324
1325 list_add(&psock->psock_list, head);
1326 psock->index = index;
1327
1328 KCM_STATS_INCR(mux->stats.psock_attach);
1329 mux->psocks_cnt++;
1330 psock_now_avail(psock);
1331 spin_unlock_bh(&mux->lock);
1332
1333 /* Schedule RX work in case there are already bytes queued */
1334 strp_check_rcv(&psock->strp);
1335
1336 out:
1337 release_sock(csk);
1338
1339 return err;
1340 }
1341
kcm_attach_ioctl(struct socket * sock,struct kcm_attach * info)1342 static int kcm_attach_ioctl(struct socket *sock, struct kcm_attach *info)
1343 {
1344 struct socket *csock;
1345 struct bpf_prog *prog;
1346 int err;
1347
1348 csock = sockfd_lookup(info->fd, &err);
1349 if (!csock)
1350 return -ENOENT;
1351
1352 prog = bpf_prog_get_type(info->bpf_fd, BPF_PROG_TYPE_SOCKET_FILTER);
1353 if (IS_ERR(prog)) {
1354 err = PTR_ERR(prog);
1355 goto out;
1356 }
1357
1358 err = kcm_attach(sock, csock, prog);
1359 if (err) {
1360 bpf_prog_put(prog);
1361 goto out;
1362 }
1363
1364 /* Keep reference on file also */
1365
1366 return 0;
1367 out:
1368 sockfd_put(csock);
1369 return err;
1370 }
1371
kcm_unattach(struct kcm_psock * psock)1372 static void kcm_unattach(struct kcm_psock *psock)
1373 {
1374 struct sock *csk = psock->sk;
1375 struct kcm_mux *mux = psock->mux;
1376
1377 lock_sock(csk);
1378
1379 /* Stop getting callbacks from TCP socket. After this there should
1380 * be no way to reserve a kcm for this psock.
1381 */
1382 write_lock_bh(&csk->sk_callback_lock);
1383 csk->sk_user_data = NULL;
1384 csk->sk_data_ready = psock->save_data_ready;
1385 csk->sk_write_space = psock->save_write_space;
1386 csk->sk_state_change = psock->save_state_change;
1387 strp_stop(&psock->strp);
1388
1389 if (WARN_ON(psock->rx_kcm)) {
1390 write_unlock_bh(&csk->sk_callback_lock);
1391 release_sock(csk);
1392 return;
1393 }
1394
1395 spin_lock_bh(&mux->rx_lock);
1396
1397 /* Stop receiver activities. After this point psock should not be
1398 * able to get onto ready list either through callbacks or work.
1399 */
1400 if (psock->ready_rx_msg) {
1401 list_del(&psock->psock_ready_list);
1402 kfree_skb(psock->ready_rx_msg);
1403 psock->ready_rx_msg = NULL;
1404 KCM_STATS_INCR(mux->stats.rx_ready_drops);
1405 }
1406
1407 spin_unlock_bh(&mux->rx_lock);
1408
1409 write_unlock_bh(&csk->sk_callback_lock);
1410
1411 /* Call strp_done without sock lock */
1412 release_sock(csk);
1413 strp_done(&psock->strp);
1414 lock_sock(csk);
1415
1416 bpf_prog_put(psock->bpf_prog);
1417
1418 spin_lock_bh(&mux->lock);
1419
1420 aggregate_psock_stats(&psock->stats, &mux->aggregate_psock_stats);
1421 save_strp_stats(&psock->strp, &mux->aggregate_strp_stats);
1422
1423 KCM_STATS_INCR(mux->stats.psock_unattach);
1424
1425 if (psock->tx_kcm) {
1426 /* psock was reserved. Just mark it finished and we will clean
1427 * up in the kcm paths, we need kcm lock which can not be
1428 * acquired here.
1429 */
1430 KCM_STATS_INCR(mux->stats.psock_unattach_rsvd);
1431 spin_unlock_bh(&mux->lock);
1432
1433 /* We are unattaching a socket that is reserved. Abort the
1434 * socket since we may be out of sync in sending on it. We need
1435 * to do this without the mux lock.
1436 */
1437 kcm_abort_tx_psock(psock, EPIPE, false);
1438
1439 spin_lock_bh(&mux->lock);
1440 if (!psock->tx_kcm) {
1441 /* psock now unreserved in window mux was unlocked */
1442 goto no_reserved;
1443 }
1444 psock->done = 1;
1445
1446 /* Commit done before queuing work to process it */
1447 smp_mb();
1448
1449 /* Queue tx work to make sure psock->done is handled */
1450 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
1451 spin_unlock_bh(&mux->lock);
1452 } else {
1453 no_reserved:
1454 if (!psock->tx_stopped)
1455 list_del(&psock->psock_avail_list);
1456 list_del(&psock->psock_list);
1457 mux->psocks_cnt--;
1458 spin_unlock_bh(&mux->lock);
1459
1460 sock_put(csk);
1461 fput(csk->sk_socket->file);
1462 kmem_cache_free(kcm_psockp, psock);
1463 }
1464
1465 release_sock(csk);
1466 }
1467
kcm_unattach_ioctl(struct socket * sock,struct kcm_unattach * info)1468 static int kcm_unattach_ioctl(struct socket *sock, struct kcm_unattach *info)
1469 {
1470 struct kcm_sock *kcm = kcm_sk(sock->sk);
1471 struct kcm_mux *mux = kcm->mux;
1472 struct kcm_psock *psock;
1473 struct socket *csock;
1474 struct sock *csk;
1475 int err;
1476
1477 csock = sockfd_lookup(info->fd, &err);
1478 if (!csock)
1479 return -ENOENT;
1480
1481 csk = csock->sk;
1482 if (!csk) {
1483 err = -EINVAL;
1484 goto out;
1485 }
1486
1487 err = -ENOENT;
1488
1489 spin_lock_bh(&mux->lock);
1490
1491 list_for_each_entry(psock, &mux->psocks, psock_list) {
1492 if (psock->sk != csk)
1493 continue;
1494
1495 /* Found the matching psock */
1496
1497 if (psock->unattaching || WARN_ON(psock->done)) {
1498 err = -EALREADY;
1499 break;
1500 }
1501
1502 psock->unattaching = 1;
1503
1504 spin_unlock_bh(&mux->lock);
1505
1506 /* Lower socket lock should already be held */
1507 kcm_unattach(psock);
1508
1509 err = 0;
1510 goto out;
1511 }
1512
1513 spin_unlock_bh(&mux->lock);
1514
1515 out:
1516 sockfd_put(csock);
1517 return err;
1518 }
1519
1520 static struct proto kcm_proto = {
1521 .name = "KCM",
1522 .owner = THIS_MODULE,
1523 .obj_size = sizeof(struct kcm_sock),
1524 };
1525
1526 /* Clone a kcm socket. */
kcm_clone(struct socket * osock)1527 static struct file *kcm_clone(struct socket *osock)
1528 {
1529 struct socket *newsock;
1530 struct sock *newsk;
1531
1532 newsock = sock_alloc();
1533 if (!newsock)
1534 return ERR_PTR(-ENFILE);
1535
1536 newsock->type = osock->type;
1537 newsock->ops = osock->ops;
1538
1539 __module_get(newsock->ops->owner);
1540
1541 newsk = sk_alloc(sock_net(osock->sk), PF_KCM, GFP_KERNEL,
1542 &kcm_proto, false);
1543 if (!newsk) {
1544 sock_release(newsock);
1545 return ERR_PTR(-ENOMEM);
1546 }
1547 sock_init_data(newsock, newsk);
1548 init_kcm_sock(kcm_sk(newsk), kcm_sk(osock->sk)->mux);
1549
1550 return sock_alloc_file(newsock, 0, osock->sk->sk_prot_creator->name);
1551 }
1552
kcm_ioctl(struct socket * sock,unsigned int cmd,unsigned long arg)1553 static int kcm_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
1554 {
1555 int err;
1556
1557 switch (cmd) {
1558 case SIOCKCMATTACH: {
1559 struct kcm_attach info;
1560
1561 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1562 return -EFAULT;
1563
1564 err = kcm_attach_ioctl(sock, &info);
1565
1566 break;
1567 }
1568 case SIOCKCMUNATTACH: {
1569 struct kcm_unattach info;
1570
1571 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1572 return -EFAULT;
1573
1574 err = kcm_unattach_ioctl(sock, &info);
1575
1576 break;
1577 }
1578 case SIOCKCMCLONE: {
1579 struct kcm_clone info;
1580
1581 FD_PREPARE(fdf, 0, kcm_clone(sock));
1582 if (fdf.err)
1583 return fdf.err;
1584
1585 info.fd = fd_prepare_fd(fdf);
1586 if (copy_to_user((void __user *)arg, &info, sizeof(info)))
1587 return -EFAULT;
1588
1589 fd_publish(fdf);
1590 err = 0;
1591 break;
1592 }
1593 default:
1594 err = -ENOIOCTLCMD;
1595 break;
1596 }
1597
1598 return err;
1599 }
1600
release_mux(struct kcm_mux * mux)1601 static void release_mux(struct kcm_mux *mux)
1602 {
1603 struct kcm_net *knet = mux->knet;
1604 struct kcm_psock *psock, *tmp_psock;
1605
1606 /* Release psocks */
1607 list_for_each_entry_safe(psock, tmp_psock,
1608 &mux->psocks, psock_list) {
1609 if (!WARN_ON(psock->unattaching))
1610 kcm_unattach(psock);
1611 }
1612
1613 if (WARN_ON(mux->psocks_cnt))
1614 return;
1615
1616 __skb_queue_purge(&mux->rx_hold_queue);
1617
1618 mutex_lock(&knet->mutex);
1619 aggregate_mux_stats(&mux->stats, &knet->aggregate_mux_stats);
1620 aggregate_psock_stats(&mux->aggregate_psock_stats,
1621 &knet->aggregate_psock_stats);
1622 aggregate_strp_stats(&mux->aggregate_strp_stats,
1623 &knet->aggregate_strp_stats);
1624 list_del_rcu(&mux->kcm_mux_list);
1625 knet->count--;
1626 mutex_unlock(&knet->mutex);
1627
1628 kfree_rcu(mux, rcu);
1629 }
1630
kcm_done(struct kcm_sock * kcm)1631 static void kcm_done(struct kcm_sock *kcm)
1632 {
1633 struct kcm_mux *mux = kcm->mux;
1634 struct sock *sk = &kcm->sk;
1635 int socks_cnt;
1636
1637 spin_lock_bh(&mux->rx_lock);
1638 if (kcm->rx_psock) {
1639 /* Cleanup in unreserve_rx_kcm */
1640 WARN_ON(kcm->done);
1641 kcm->rx_disabled = 1;
1642 kcm->done = 1;
1643 spin_unlock_bh(&mux->rx_lock);
1644 return;
1645 }
1646
1647 if (kcm->rx_wait) {
1648 list_del(&kcm->wait_rx_list);
1649 /* paired with lockless reads in kcm_rfree() */
1650 WRITE_ONCE(kcm->rx_wait, false);
1651 }
1652 /* Move any pending receive messages to other kcm sockets */
1653 requeue_rx_msgs(mux, &sk->sk_receive_queue);
1654
1655 spin_unlock_bh(&mux->rx_lock);
1656
1657 if (WARN_ON(sk_rmem_alloc_get(sk)))
1658 return;
1659
1660 /* Detach from MUX */
1661 spin_lock_bh(&mux->lock);
1662
1663 list_del(&kcm->kcm_sock_list);
1664 mux->kcm_socks_cnt--;
1665 socks_cnt = mux->kcm_socks_cnt;
1666
1667 spin_unlock_bh(&mux->lock);
1668
1669 if (!socks_cnt) {
1670 /* We are done with the mux now. */
1671 release_mux(mux);
1672 }
1673
1674 WARN_ON(kcm->rx_wait);
1675
1676 sock_put(&kcm->sk);
1677 }
1678
1679 /* Called by kcm_release to close a KCM socket.
1680 * If this is the last KCM socket on the MUX, destroy the MUX.
1681 */
kcm_release(struct socket * sock)1682 static int kcm_release(struct socket *sock)
1683 {
1684 struct sock *sk = sock->sk;
1685 struct kcm_sock *kcm;
1686 struct kcm_mux *mux;
1687 struct kcm_psock *psock;
1688
1689 if (!sk)
1690 return 0;
1691
1692 kcm = kcm_sk(sk);
1693 mux = kcm->mux;
1694
1695 lock_sock(sk);
1696 sock_orphan(sk);
1697 kfree_skb(kcm->seq_skb);
1698
1699 /* Purge queue under lock to avoid race condition with tx_work trying
1700 * to act when queue is nonempty. If tx_work runs after this point
1701 * it will just return.
1702 */
1703 __skb_queue_purge(&sk->sk_write_queue);
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 disable_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