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/rcupdate.h>
9 #include <linux/bpf.h>
10 #include <linux/errno.h>
11 #include <linux/errqueue.h>
12 #include <linux/file.h>
13 #include <linux/filter.h>
14 #include <linux/in.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/net.h>
18 #include <linux/netdevice.h>
19 #include <linux/poll.h>
20 #include <linux/rculist.h>
21 #include <linux/skbuff.h>
22 #include <linux/socket.h>
23 #include <linux/splice.h>
24 #include <linux/uaccess.h>
25 #include <linux/workqueue.h>
26 #include <linux/syscalls.h>
27 #include <linux/sched/signal.h>
28 #include <linux/uio.h>
29
30 #include <net/kcm.h>
31 #include <net/netns/generic.h>
32 #include <net/sock.h>
33 #include <uapi/linux/kcm.h>
34 #include <trace/events/sock.h>
35
36 unsigned int kcm_net_id;
37
38 static struct kmem_cache *kcm_psockp __read_mostly;
39 static struct kmem_cache *kcm_muxp __read_mostly;
40 static struct workqueue_struct *kcm_wq;
41
kcm_sk(const struct sock * sk)42 static inline struct kcm_sock *kcm_sk(const struct sock *sk)
43 {
44 return (struct kcm_sock *)sk;
45 }
46
kcm_tx_msg(struct sk_buff * skb)47 static inline struct kcm_tx_msg *kcm_tx_msg(struct sk_buff *skb)
48 {
49 return (struct kcm_tx_msg *)skb->cb;
50 }
51
report_csk_error(struct sock * csk,int err)52 static void report_csk_error(struct sock *csk, int err)
53 {
54 csk->sk_err = EPIPE;
55 sk_error_report(csk);
56 }
57
kcm_abort_tx_psock(struct kcm_psock * psock,int err,bool wakeup_kcm)58 static void kcm_abort_tx_psock(struct kcm_psock *psock, int err,
59 bool wakeup_kcm)
60 {
61 struct sock *csk = psock->sk;
62 struct kcm_mux *mux = psock->mux;
63
64 /* Unrecoverable error in transmit */
65
66 spin_lock_bh(&mux->lock);
67
68 if (psock->tx_stopped) {
69 spin_unlock_bh(&mux->lock);
70 return;
71 }
72
73 psock->tx_stopped = 1;
74 KCM_STATS_INCR(psock->stats.tx_aborts);
75
76 if (!psock->tx_kcm) {
77 /* Take off psocks_avail list */
78 list_del(&psock->psock_avail_list);
79 } else if (wakeup_kcm) {
80 /* In this case psock is being aborted while outside of
81 * write_msgs and psock is reserved. Schedule tx_work
82 * to handle the failure there. Need to commit tx_stopped
83 * before queuing work.
84 */
85 smp_mb();
86
87 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
88 }
89
90 spin_unlock_bh(&mux->lock);
91
92 /* Report error on lower socket */
93 report_csk_error(csk, err);
94 }
95
96 /* RX mux lock held. */
kcm_update_rx_mux_stats(struct kcm_mux * mux,struct kcm_psock * psock)97 static void kcm_update_rx_mux_stats(struct kcm_mux *mux,
98 struct kcm_psock *psock)
99 {
100 STRP_STATS_ADD(mux->stats.rx_bytes,
101 psock->strp.stats.bytes -
102 psock->saved_rx_bytes);
103 mux->stats.rx_msgs +=
104 psock->strp.stats.msgs - psock->saved_rx_msgs;
105 psock->saved_rx_msgs = psock->strp.stats.msgs;
106 psock->saved_rx_bytes = psock->strp.stats.bytes;
107 }
108
kcm_update_tx_mux_stats(struct kcm_mux * mux,struct kcm_psock * psock)109 static void kcm_update_tx_mux_stats(struct kcm_mux *mux,
110 struct kcm_psock *psock)
111 {
112 KCM_STATS_ADD(mux->stats.tx_bytes,
113 psock->stats.tx_bytes - psock->saved_tx_bytes);
114 mux->stats.tx_msgs +=
115 psock->stats.tx_msgs - psock->saved_tx_msgs;
116 psock->saved_tx_msgs = psock->stats.tx_msgs;
117 psock->saved_tx_bytes = psock->stats.tx_bytes;
118 }
119
120 static int kcm_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
121
122 /* KCM is ready to receive messages on its queue-- either the KCM is new or
123 * has become unblocked after being blocked on full socket buffer. Queue any
124 * pending ready messages on a psock. RX mux lock held.
125 */
kcm_rcv_ready(struct kcm_sock * kcm)126 static void kcm_rcv_ready(struct kcm_sock *kcm)
127 {
128 struct kcm_mux *mux = kcm->mux;
129 struct kcm_psock *psock;
130 struct sk_buff *skb;
131
132 if (unlikely(kcm->rx_wait || kcm->rx_psock || kcm->rx_disabled))
133 return;
134
135 while (unlikely((skb = __skb_dequeue(&mux->rx_hold_queue)))) {
136 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
137 /* Assuming buffer limit has been reached */
138 skb_queue_head(&mux->rx_hold_queue, skb);
139 WARN_ON(!sk_rmem_alloc_get(&kcm->sk));
140 return;
141 }
142 }
143
144 while (!list_empty(&mux->psocks_ready)) {
145 psock = list_first_entry(&mux->psocks_ready, struct kcm_psock,
146 psock_ready_list);
147
148 if (kcm_queue_rcv_skb(&kcm->sk, psock->ready_rx_msg)) {
149 /* Assuming buffer limit has been reached */
150 WARN_ON(!sk_rmem_alloc_get(&kcm->sk));
151 return;
152 }
153
154 /* Consumed the ready message on the psock. Schedule rx_work to
155 * get more messages.
156 */
157 list_del(&psock->psock_ready_list);
158 psock->ready_rx_msg = NULL;
159 /* Commit clearing of ready_rx_msg for queuing work */
160 smp_mb();
161
162 strp_unpause(&psock->strp);
163 strp_check_rcv(&psock->strp);
164 }
165
166 /* Buffer limit is okay now, add to ready list */
167 list_add_tail(&kcm->wait_rx_list,
168 &kcm->mux->kcm_rx_waiters);
169 /* paired with lockless reads in kcm_rfree() */
170 WRITE_ONCE(kcm->rx_wait, true);
171 }
172
kcm_rfree(struct sk_buff * skb)173 static void kcm_rfree(struct sk_buff *skb)
174 {
175 struct sock *sk = skb->sk;
176 struct kcm_sock *kcm = kcm_sk(sk);
177 struct kcm_mux *mux = kcm->mux;
178 unsigned int len = skb->truesize;
179
180 sk_mem_uncharge(sk, len);
181 atomic_sub(len, &sk->sk_rmem_alloc);
182
183 /* For reading rx_wait and rx_psock without holding lock */
184 smp_mb__after_atomic();
185
186 if (!READ_ONCE(kcm->rx_wait) && !READ_ONCE(kcm->rx_psock) &&
187 sk_rmem_alloc_get(sk) < sk->sk_rcvlowat) {
188 spin_lock_bh(&mux->rx_lock);
189 kcm_rcv_ready(kcm);
190 spin_unlock_bh(&mux->rx_lock);
191 }
192 }
193
kcm_queue_rcv_skb(struct sock * sk,struct sk_buff * skb)194 static int kcm_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
195 {
196 struct sk_buff_head *list = &sk->sk_receive_queue;
197
198 if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
199 return -ENOMEM;
200
201 if (!sk_rmem_schedule(sk, skb, skb->truesize))
202 return -ENOBUFS;
203
204 skb->dev = NULL;
205
206 skb_orphan(skb);
207 skb->sk = sk;
208 skb->destructor = kcm_rfree;
209 atomic_add(skb->truesize, &sk->sk_rmem_alloc);
210 sk_mem_charge(sk, skb->truesize);
211
212 skb_queue_tail(list, skb);
213
214 if (!sock_flag(sk, SOCK_DEAD))
215 sk->sk_data_ready(sk);
216
217 return 0;
218 }
219
220 /* Requeue received messages for a kcm socket to other kcm sockets. This is
221 * called with a kcm socket is receive disabled.
222 * RX mux lock held.
223 */
requeue_rx_msgs(struct kcm_mux * mux,struct sk_buff_head * head)224 static void requeue_rx_msgs(struct kcm_mux *mux, struct sk_buff_head *head)
225 {
226 struct sk_buff *skb;
227 struct kcm_sock *kcm;
228
229 while ((skb = skb_dequeue(head))) {
230 /* Reset destructor to avoid calling kcm_rcv_ready */
231 skb->destructor = sock_rfree;
232 skb_orphan(skb);
233 try_again:
234 if (list_empty(&mux->kcm_rx_waiters)) {
235 skb_queue_tail(&mux->rx_hold_queue, skb);
236 continue;
237 }
238
239 kcm = list_first_entry(&mux->kcm_rx_waiters,
240 struct kcm_sock, wait_rx_list);
241
242 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
243 /* Should mean socket buffer full */
244 list_del(&kcm->wait_rx_list);
245 /* paired with lockless reads in kcm_rfree() */
246 WRITE_ONCE(kcm->rx_wait, false);
247
248 /* Commit rx_wait to read in kcm_free */
249 smp_wmb();
250
251 goto try_again;
252 }
253 }
254 }
255
256 /* Lower sock lock held */
reserve_rx_kcm(struct kcm_psock * psock,struct sk_buff * head)257 static struct kcm_sock *reserve_rx_kcm(struct kcm_psock *psock,
258 struct sk_buff *head)
259 {
260 struct kcm_mux *mux = psock->mux;
261 struct kcm_sock *kcm;
262
263 WARN_ON(psock->ready_rx_msg);
264
265 if (psock->rx_kcm)
266 return psock->rx_kcm;
267
268 spin_lock_bh(&mux->rx_lock);
269
270 if (psock->rx_kcm) {
271 spin_unlock_bh(&mux->rx_lock);
272 return psock->rx_kcm;
273 }
274
275 kcm_update_rx_mux_stats(mux, psock);
276
277 if (list_empty(&mux->kcm_rx_waiters)) {
278 psock->ready_rx_msg = head;
279 strp_pause(&psock->strp);
280 list_add_tail(&psock->psock_ready_list,
281 &mux->psocks_ready);
282 spin_unlock_bh(&mux->rx_lock);
283 return NULL;
284 }
285
286 kcm = list_first_entry(&mux->kcm_rx_waiters,
287 struct kcm_sock, wait_rx_list);
288 list_del(&kcm->wait_rx_list);
289 /* paired with lockless reads in kcm_rfree() */
290 WRITE_ONCE(kcm->rx_wait, false);
291
292 psock->rx_kcm = kcm;
293 /* paired with lockless reads in kcm_rfree() */
294 WRITE_ONCE(kcm->rx_psock, psock);
295
296 spin_unlock_bh(&mux->rx_lock);
297
298 return kcm;
299 }
300
301 static void kcm_done(struct kcm_sock *kcm);
302
kcm_done_work(struct work_struct * w)303 static void kcm_done_work(struct work_struct *w)
304 {
305 kcm_done(container_of(w, struct kcm_sock, done_work));
306 }
307
308 /* Lower sock held */
unreserve_rx_kcm(struct kcm_psock * psock,bool rcv_ready)309 static void unreserve_rx_kcm(struct kcm_psock *psock,
310 bool rcv_ready)
311 {
312 struct kcm_sock *kcm = psock->rx_kcm;
313 struct kcm_mux *mux = psock->mux;
314
315 if (!kcm)
316 return;
317
318 spin_lock_bh(&mux->rx_lock);
319
320 psock->rx_kcm = NULL;
321 /* paired with lockless reads in kcm_rfree() */
322 WRITE_ONCE(kcm->rx_psock, NULL);
323
324 /* Commit kcm->rx_psock before sk_rmem_alloc_get to sync with
325 * kcm_rfree
326 */
327 smp_mb();
328
329 if (unlikely(kcm->done)) {
330 spin_unlock_bh(&mux->rx_lock);
331
332 /* Need to run kcm_done in a task since we need to qcquire
333 * callback locks which may already be held here.
334 */
335 INIT_WORK(&kcm->done_work, kcm_done_work);
336 schedule_work(&kcm->done_work);
337 return;
338 }
339
340 if (unlikely(kcm->rx_disabled)) {
341 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
342 } else if (rcv_ready || unlikely(!sk_rmem_alloc_get(&kcm->sk))) {
343 /* Check for degenerative race with rx_wait that all
344 * data was dequeued (accounted for in kcm_rfree).
345 */
346 kcm_rcv_ready(kcm);
347 }
348 spin_unlock_bh(&mux->rx_lock);
349 }
350
351 /* Lower sock lock held */
psock_data_ready(struct sock * sk)352 static void psock_data_ready(struct sock *sk)
353 {
354 struct kcm_psock *psock;
355
356 trace_sk_data_ready(sk);
357
358 read_lock_bh(&sk->sk_callback_lock);
359
360 psock = (struct kcm_psock *)sk->sk_user_data;
361 if (likely(psock))
362 strp_data_ready(&psock->strp);
363
364 read_unlock_bh(&sk->sk_callback_lock);
365 }
366
367 /* Called with lower sock held */
kcm_rcv_strparser(struct strparser * strp,struct sk_buff * skb)368 static void kcm_rcv_strparser(struct strparser *strp, struct sk_buff *skb)
369 {
370 struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
371 struct kcm_sock *kcm;
372
373 try_queue:
374 kcm = reserve_rx_kcm(psock, skb);
375 if (!kcm) {
376 /* Unable to reserve a KCM, message is held in psock and strp
377 * is paused.
378 */
379 return;
380 }
381
382 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
383 /* Should mean socket buffer full */
384 unreserve_rx_kcm(psock, false);
385 goto try_queue;
386 }
387 }
388
kcm_parse_func_strparser(struct strparser * strp,struct sk_buff * skb)389 static int kcm_parse_func_strparser(struct strparser *strp, struct sk_buff *skb)
390 {
391 struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
392 struct bpf_prog *prog = psock->bpf_prog;
393 int res;
394
395 rcu_read_lock();
396 res = bpf_prog_run_pin_on_cpu(prog, skb);
397 rcu_read_unlock();
398 return res;
399 }
400
kcm_read_sock_done(struct strparser * strp,int err)401 static int kcm_read_sock_done(struct strparser *strp, int err)
402 {
403 struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
404
405 unreserve_rx_kcm(psock, true);
406
407 return err;
408 }
409
psock_state_change(struct sock * sk)410 static void psock_state_change(struct sock *sk)
411 {
412 /* TCP only does a EPOLLIN for a half close. Do a EPOLLHUP here
413 * since application will normally not poll with EPOLLIN
414 * on the TCP sockets.
415 */
416
417 report_csk_error(sk, EPIPE);
418 }
419
psock_write_space(struct sock * sk)420 static void psock_write_space(struct sock *sk)
421 {
422 struct kcm_psock *psock;
423 struct kcm_mux *mux;
424 struct kcm_sock *kcm;
425
426 read_lock_bh(&sk->sk_callback_lock);
427
428 psock = (struct kcm_psock *)sk->sk_user_data;
429 if (unlikely(!psock))
430 goto out;
431 mux = psock->mux;
432
433 spin_lock_bh(&mux->lock);
434
435 /* Check if the socket is reserved so someone is waiting for sending. */
436 kcm = psock->tx_kcm;
437 if (kcm)
438 queue_work(kcm_wq, &kcm->tx_work);
439
440 spin_unlock_bh(&mux->lock);
441 out:
442 read_unlock_bh(&sk->sk_callback_lock);
443 }
444
445 static void unreserve_psock(struct kcm_sock *kcm);
446
447 /* kcm sock is locked. */
reserve_psock(struct kcm_sock * kcm)448 static struct kcm_psock *reserve_psock(struct kcm_sock *kcm)
449 {
450 struct kcm_mux *mux = kcm->mux;
451 struct kcm_psock *psock;
452
453 psock = kcm->tx_psock;
454
455 smp_rmb(); /* Must read tx_psock before tx_wait */
456
457 if (psock) {
458 WARN_ON(kcm->tx_wait);
459 if (unlikely(psock->tx_stopped))
460 unreserve_psock(kcm);
461 else
462 return kcm->tx_psock;
463 }
464
465 spin_lock_bh(&mux->lock);
466
467 /* Check again under lock to see if psock was reserved for this
468 * psock via psock_unreserve.
469 */
470 psock = kcm->tx_psock;
471 if (unlikely(psock)) {
472 WARN_ON(kcm->tx_wait);
473 spin_unlock_bh(&mux->lock);
474 return kcm->tx_psock;
475 }
476
477 if (!list_empty(&mux->psocks_avail)) {
478 psock = list_first_entry(&mux->psocks_avail,
479 struct kcm_psock,
480 psock_avail_list);
481 list_del(&psock->psock_avail_list);
482 if (kcm->tx_wait) {
483 list_del(&kcm->wait_psock_list);
484 kcm->tx_wait = false;
485 }
486 kcm->tx_psock = psock;
487 psock->tx_kcm = kcm;
488 KCM_STATS_INCR(psock->stats.reserved);
489 } else if (!kcm->tx_wait) {
490 list_add_tail(&kcm->wait_psock_list,
491 &mux->kcm_tx_waiters);
492 kcm->tx_wait = true;
493 }
494
495 spin_unlock_bh(&mux->lock);
496
497 return psock;
498 }
499
500 /* mux lock held */
psock_now_avail(struct kcm_psock * psock)501 static void psock_now_avail(struct kcm_psock *psock)
502 {
503 struct kcm_mux *mux = psock->mux;
504 struct kcm_sock *kcm;
505
506 if (list_empty(&mux->kcm_tx_waiters)) {
507 list_add_tail(&psock->psock_avail_list,
508 &mux->psocks_avail);
509 } else {
510 kcm = list_first_entry(&mux->kcm_tx_waiters,
511 struct kcm_sock,
512 wait_psock_list);
513 list_del(&kcm->wait_psock_list);
514 kcm->tx_wait = false;
515 psock->tx_kcm = kcm;
516
517 /* Commit before changing tx_psock since that is read in
518 * reserve_psock before queuing work.
519 */
520 smp_mb();
521
522 kcm->tx_psock = psock;
523 KCM_STATS_INCR(psock->stats.reserved);
524 queue_work(kcm_wq, &kcm->tx_work);
525 }
526 }
527
528 /* kcm sock is locked. */
unreserve_psock(struct kcm_sock * kcm)529 static void unreserve_psock(struct kcm_sock *kcm)
530 {
531 struct kcm_psock *psock;
532 struct kcm_mux *mux = kcm->mux;
533
534 spin_lock_bh(&mux->lock);
535
536 psock = kcm->tx_psock;
537
538 if (WARN_ON(!psock)) {
539 spin_unlock_bh(&mux->lock);
540 return;
541 }
542
543 smp_rmb(); /* Read tx_psock before tx_wait */
544
545 kcm_update_tx_mux_stats(mux, psock);
546
547 WARN_ON(kcm->tx_wait);
548
549 kcm->tx_psock = NULL;
550 psock->tx_kcm = NULL;
551 KCM_STATS_INCR(psock->stats.unreserved);
552
553 if (unlikely(psock->tx_stopped)) {
554 if (psock->done) {
555 /* Deferred free */
556 list_del(&psock->psock_list);
557 mux->psocks_cnt--;
558 sock_put(psock->sk);
559 fput(psock->sk->sk_socket->file);
560 kmem_cache_free(kcm_psockp, psock);
561 }
562
563 /* Don't put back on available list */
564
565 spin_unlock_bh(&mux->lock);
566
567 return;
568 }
569
570 psock_now_avail(psock);
571
572 spin_unlock_bh(&mux->lock);
573 }
574
kcm_report_tx_retry(struct kcm_sock * kcm)575 static void kcm_report_tx_retry(struct kcm_sock *kcm)
576 {
577 struct kcm_mux *mux = kcm->mux;
578
579 spin_lock_bh(&mux->lock);
580 KCM_STATS_INCR(mux->stats.tx_retries);
581 spin_unlock_bh(&mux->lock);
582 }
583
584 /* Write any messages ready on the kcm socket. Called with kcm sock lock
585 * held. Return bytes actually sent or error.
586 */
kcm_write_msgs(struct kcm_sock * kcm)587 static int kcm_write_msgs(struct kcm_sock *kcm)
588 {
589 unsigned int total_sent = 0;
590 struct sock *sk = &kcm->sk;
591 struct kcm_psock *psock;
592 struct sk_buff *head;
593 int ret = 0;
594
595 kcm->tx_wait_more = false;
596 psock = kcm->tx_psock;
597 if (unlikely(psock && psock->tx_stopped)) {
598 /* A reserved psock was aborted asynchronously. Unreserve
599 * it and we'll retry the message.
600 */
601 unreserve_psock(kcm);
602 kcm_report_tx_retry(kcm);
603 if (skb_queue_empty(&sk->sk_write_queue))
604 return 0;
605
606 kcm_tx_msg(skb_peek(&sk->sk_write_queue))->started_tx = false;
607 }
608
609 retry:
610 while ((head = skb_peek(&sk->sk_write_queue))) {
611 struct msghdr msg = {
612 .msg_flags = MSG_DONTWAIT | MSG_SPLICE_PAGES,
613 };
614 struct kcm_tx_msg *txm = kcm_tx_msg(head);
615 struct sk_buff *skb;
616 unsigned int msize;
617 int i;
618
619 if (!txm->started_tx) {
620 psock = reserve_psock(kcm);
621 if (!psock)
622 goto out;
623 skb = head;
624 txm->frag_offset = 0;
625 txm->sent = 0;
626 txm->started_tx = true;
627 } else {
628 if (WARN_ON(!psock)) {
629 ret = -EINVAL;
630 goto out;
631 }
632 skb = txm->frag_skb;
633 }
634
635 if (WARN_ON_ONCE(!skb_shinfo(skb)->nr_frags) ||
636 WARN_ON_ONCE(!skb_frag_page(&skb_shinfo(skb)->frags[0]))) {
637 ret = -EINVAL;
638 goto out;
639 }
640
641 msize = 0;
642 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
643 msize += skb_frag_size(&skb_shinfo(skb)->frags[i]);
644
645 iov_iter_bvec(&msg.msg_iter, ITER_SOURCE,
646 (const struct bio_vec *)skb_shinfo(skb)->frags,
647 skb_shinfo(skb)->nr_frags, msize);
648 iov_iter_advance(&msg.msg_iter, txm->frag_offset);
649
650 do {
651 ret = sock_sendmsg(psock->sk->sk_socket, &msg);
652 if (ret <= 0) {
653 if (ret == -EAGAIN) {
654 /* Save state to try again when there's
655 * write space on the socket
656 */
657 txm->frag_skb = skb;
658 ret = 0;
659 goto out;
660 }
661
662 /* Hard failure in sending message, abort this
663 * psock since it has lost framing
664 * synchronization and retry sending the
665 * message from the beginning.
666 */
667 kcm_abort_tx_psock(psock, ret ? -ret : EPIPE,
668 true);
669 unreserve_psock(kcm);
670 psock = NULL;
671
672 txm->started_tx = false;
673 kcm_report_tx_retry(kcm);
674 ret = 0;
675 goto retry;
676 }
677
678 txm->sent += ret;
679 txm->frag_offset += ret;
680 KCM_STATS_ADD(psock->stats.tx_bytes, ret);
681 } while (msg.msg_iter.count > 0);
682
683 if (skb == head) {
684 if (skb_has_frag_list(skb)) {
685 txm->frag_skb = skb_shinfo(skb)->frag_list;
686 txm->frag_offset = 0;
687 continue;
688 }
689 } else if (skb->next) {
690 txm->frag_skb = skb->next;
691 txm->frag_offset = 0;
692 continue;
693 }
694
695 /* Successfully sent the whole packet, account for it. */
696 sk->sk_wmem_queued -= txm->sent;
697 total_sent += txm->sent;
698 skb_dequeue(&sk->sk_write_queue);
699 kfree_skb(head);
700 KCM_STATS_INCR(psock->stats.tx_msgs);
701 }
702 out:
703 if (!head) {
704 /* Done with all queued messages. */
705 WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
706 if (psock)
707 unreserve_psock(kcm);
708 }
709
710 /* Check if write space is available */
711 sk->sk_write_space(sk);
712
713 return total_sent ? : ret;
714 }
715
kcm_tx_work(struct work_struct * w)716 static void kcm_tx_work(struct work_struct *w)
717 {
718 struct kcm_sock *kcm = container_of(w, struct kcm_sock, tx_work);
719 struct sock *sk = &kcm->sk;
720 int err;
721
722 lock_sock(sk);
723
724 /* Primarily for SOCK_DGRAM sockets, also handle asynchronous tx
725 * aborts
726 */
727 err = kcm_write_msgs(kcm);
728 if (err < 0) {
729 /* Hard failure in write, report error on KCM socket */
730 pr_warn("KCM: Hard failure on kcm_write_msgs %d\n", err);
731 report_csk_error(&kcm->sk, -err);
732 goto out;
733 }
734
735 /* Primarily for SOCK_SEQPACKET sockets */
736 if (likely(sk->sk_socket) &&
737 test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
738 clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
739 sk->sk_write_space(sk);
740 }
741
742 out:
743 release_sock(sk);
744 }
745
kcm_push(struct kcm_sock * kcm)746 static void kcm_push(struct kcm_sock *kcm)
747 {
748 if (kcm->tx_wait_more)
749 kcm_write_msgs(kcm);
750 }
751
kcm_sendmsg(struct socket * sock,struct msghdr * msg,size_t len)752 static int kcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
753 {
754 struct sock *sk = sock->sk;
755 struct kcm_sock *kcm = kcm_sk(sk);
756 struct sk_buff *skb = NULL, *head = NULL, *frag_prev = NULL;
757 size_t copy, copied = 0;
758 long timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
759 int eor = (sock->type == SOCK_DGRAM) ?
760 !(msg->msg_flags & MSG_MORE) : !!(msg->msg_flags & MSG_EOR);
761 int err = -EPIPE;
762
763 mutex_lock(&kcm->tx_mutex);
764 lock_sock(sk);
765
766 /* Per tcp_sendmsg this should be in poll */
767 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
768
769 if (sk->sk_err)
770 goto out_error;
771
772 if (kcm->seq_skb) {
773 /* Previously opened message */
774 head = kcm->seq_skb;
775 skb = kcm_tx_msg(head)->last_skb;
776 goto start;
777 }
778
779 /* Call the sk_stream functions to manage the sndbuf mem. */
780 if (!sk_stream_memory_free(sk)) {
781 kcm_push(kcm);
782 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
783 err = sk_stream_wait_memory(sk, &timeo);
784 if (err)
785 goto out_error;
786 }
787
788 if (msg_data_left(msg)) {
789 /* New message, alloc head skb */
790 head = alloc_skb(0, sk->sk_allocation);
791 while (!head) {
792 kcm_push(kcm);
793 err = sk_stream_wait_memory(sk, &timeo);
794 if (err)
795 goto out_error;
796
797 head = alloc_skb(0, sk->sk_allocation);
798 }
799
800 skb = head;
801
802 /* Set ip_summed to CHECKSUM_UNNECESSARY to avoid calling
803 * csum_and_copy_from_iter from skb_do_copy_data_nocache.
804 */
805 skb->ip_summed = CHECKSUM_UNNECESSARY;
806 }
807
808 start:
809 while (msg_data_left(msg)) {
810 bool merge = true;
811 int i = skb_shinfo(skb)->nr_frags;
812 struct page_frag *pfrag = sk_page_frag(sk);
813
814 if (!sk_page_frag_refill(sk, pfrag))
815 goto wait_for_memory;
816
817 if (!skb_can_coalesce(skb, i, pfrag->page,
818 pfrag->offset)) {
819 if (i == MAX_SKB_FRAGS) {
820 struct sk_buff *tskb;
821
822 tskb = alloc_skb(0, sk->sk_allocation);
823 if (!tskb)
824 goto wait_for_memory;
825
826 if (head == skb)
827 skb_shinfo(head)->frag_list = tskb;
828 else
829 skb->next = tskb;
830
831 frag_prev = skb;
832 skb = tskb;
833 skb->ip_summed = CHECKSUM_UNNECESSARY;
834 continue;
835 }
836 merge = false;
837 }
838
839 if (msg->msg_flags & MSG_SPLICE_PAGES) {
840 copy = msg_data_left(msg);
841 if (!sk_wmem_schedule(sk, copy))
842 goto wait_for_memory;
843
844 err = skb_splice_from_iter(skb, &msg->msg_iter, copy);
845 if (err < 0) {
846 if (err == -EMSGSIZE)
847 goto wait_for_memory;
848 goto out_error;
849 }
850
851 copy = err;
852 skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
853 sk_wmem_queued_add(sk, copy);
854 sk_mem_charge(sk, copy);
855
856 if (head != skb)
857 head->truesize += copy;
858 } else {
859 copy = min_t(int, msg_data_left(msg),
860 pfrag->size - pfrag->offset);
861 if (!sk_wmem_schedule(sk, copy))
862 goto wait_for_memory;
863
864 err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
865 pfrag->page,
866 pfrag->offset,
867 copy);
868 if (err)
869 goto out_error;
870
871 /* Update the skb. */
872 if (merge) {
873 skb_frag_size_add(
874 &skb_shinfo(skb)->frags[i - 1], copy);
875 } else {
876 skb_fill_page_desc(skb, i, pfrag->page,
877 pfrag->offset, copy);
878 get_page(pfrag->page);
879 }
880
881 pfrag->offset += copy;
882 }
883
884 copied += copy;
885 if (head != skb) {
886 head->len += copy;
887 head->data_len += copy;
888 }
889
890 continue;
891
892 wait_for_memory:
893 kcm_push(kcm);
894 err = sk_stream_wait_memory(sk, &timeo);
895 if (err)
896 goto out_error;
897 }
898
899 if (eor) {
900 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
901
902 if (head) {
903 /* Message complete, queue it on send buffer */
904 __skb_queue_tail(&sk->sk_write_queue, head);
905 kcm->seq_skb = NULL;
906 KCM_STATS_INCR(kcm->stats.tx_msgs);
907 }
908
909 if (msg->msg_flags & MSG_BATCH) {
910 kcm->tx_wait_more = true;
911 } else if (kcm->tx_wait_more || not_busy) {
912 err = kcm_write_msgs(kcm);
913 if (err < 0) {
914 /* We got a hard error in write_msgs but have
915 * already queued this message. Report an error
916 * in the socket, but don't affect return value
917 * from sendmsg
918 */
919 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
920 report_csk_error(&kcm->sk, -err);
921 }
922 }
923 } else {
924 /* Message not complete, save state */
925 partial_message:
926 if (head) {
927 kcm->seq_skb = head;
928 kcm_tx_msg(head)->last_skb = skb;
929 }
930 }
931
932 KCM_STATS_ADD(kcm->stats.tx_bytes, copied);
933
934 release_sock(sk);
935 mutex_unlock(&kcm->tx_mutex);
936 return copied;
937
938 out_error:
939 kcm_push(kcm);
940
941 /* When MAX_SKB_FRAGS was reached, a new skb was allocated and
942 * linked into the frag_list before data copy. If the copy
943 * subsequently failed, this skb has zero frags. Remove it from
944 * the frag_list to prevent kcm_write_msgs from later hitting
945 * WARN_ON(!skb_shinfo(skb)->nr_frags).
946 */
947 if (frag_prev && !skb_shinfo(skb)->nr_frags) {
948 if (head == frag_prev)
949 skb_shinfo(head)->frag_list = NULL;
950 else
951 frag_prev->next = NULL;
952 kfree_skb(skb);
953 /* Update skb as it may be saved in partial_message via goto */
954 skb = frag_prev;
955 }
956
957 if (sock->type == SOCK_SEQPACKET) {
958 /* Wrote some bytes before encountering an
959 * error, return partial success.
960 */
961 if (copied)
962 goto partial_message;
963 if (head != kcm->seq_skb)
964 kfree_skb(head);
965 } else {
966 kfree_skb(head);
967 kcm->seq_skb = NULL;
968 }
969
970 err = sk_stream_error(sk, msg->msg_flags, err);
971
972 /* make sure we wake any epoll edge trigger waiter */
973 if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
974 sk->sk_write_space(sk);
975
976 release_sock(sk);
977 mutex_unlock(&kcm->tx_mutex);
978 return err;
979 }
980
kcm_splice_eof(struct socket * sock)981 static void kcm_splice_eof(struct socket *sock)
982 {
983 struct sock *sk = sock->sk;
984 struct kcm_sock *kcm = kcm_sk(sk);
985
986 if (skb_queue_empty_lockless(&sk->sk_write_queue))
987 return;
988
989 lock_sock(sk);
990 kcm_write_msgs(kcm);
991 release_sock(sk);
992 }
993
kcm_recvmsg(struct socket * sock,struct msghdr * msg,size_t len,int flags)994 static int kcm_recvmsg(struct socket *sock, struct msghdr *msg,
995 size_t len, int flags)
996 {
997 struct sock *sk = sock->sk;
998 struct kcm_sock *kcm = kcm_sk(sk);
999 int err = 0;
1000 struct strp_msg *stm;
1001 int copied = 0;
1002 struct sk_buff *skb;
1003
1004 skb = skb_recv_datagram(sk, flags, &err);
1005 if (!skb)
1006 goto out;
1007
1008 /* Okay, have a message on the receive queue */
1009
1010 stm = strp_msg(skb);
1011
1012 if (len > stm->full_len)
1013 len = stm->full_len;
1014
1015 err = skb_copy_datagram_msg(skb, stm->offset, msg, len);
1016 if (err < 0)
1017 goto out;
1018
1019 copied = len;
1020 if (likely(!(flags & MSG_PEEK))) {
1021 KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1022 if (copied < stm->full_len) {
1023 if (sock->type == SOCK_DGRAM) {
1024 /* Truncated message */
1025 msg->msg_flags |= MSG_TRUNC;
1026 goto msg_finished;
1027 }
1028 stm->offset += copied;
1029 stm->full_len -= copied;
1030 } else {
1031 msg_finished:
1032 /* Finished with message */
1033 msg->msg_flags |= MSG_EOR;
1034 KCM_STATS_INCR(kcm->stats.rx_msgs);
1035 }
1036 }
1037
1038 out:
1039 skb_free_datagram(sk, skb);
1040 return copied ? : err;
1041 }
1042
kcm_splice_read(struct socket * sock,loff_t * ppos,struct pipe_inode_info * pipe,size_t len,unsigned int flags)1043 static ssize_t kcm_splice_read(struct socket *sock, loff_t *ppos,
1044 struct pipe_inode_info *pipe, size_t len,
1045 unsigned int flags)
1046 {
1047 struct sock *sk = sock->sk;
1048 struct kcm_sock *kcm = kcm_sk(sk);
1049 struct strp_msg *stm;
1050 int err = 0;
1051 ssize_t copied;
1052 struct sk_buff *skb;
1053
1054 if (sock->file->f_flags & O_NONBLOCK || flags & SPLICE_F_NONBLOCK)
1055 flags = MSG_DONTWAIT;
1056 else
1057 flags = 0;
1058
1059 /* Only support splice for SOCKSEQPACKET */
1060
1061 skb = skb_recv_datagram(sk, flags, &err);
1062 if (!skb)
1063 goto err_out;
1064
1065 /* Okay, have a message on the receive queue */
1066
1067 stm = strp_msg(skb);
1068
1069 if (len > stm->full_len)
1070 len = stm->full_len;
1071
1072 copied = skb_splice_bits(skb, sk, stm->offset, pipe, len, flags);
1073 if (copied < 0) {
1074 err = copied;
1075 goto err_out;
1076 }
1077
1078 KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1079
1080 stm->offset += copied;
1081 stm->full_len -= copied;
1082
1083 /* We have no way to return MSG_EOR. If all the bytes have been
1084 * read we still leave the message in the receive socket buffer.
1085 * A subsequent recvmsg needs to be done to return MSG_EOR and
1086 * finish reading the message.
1087 */
1088
1089 skb_free_datagram(sk, skb);
1090 return copied;
1091
1092 err_out:
1093 skb_free_datagram(sk, skb);
1094 return err;
1095 }
1096
1097 /* kcm sock lock held */
kcm_recv_disable(struct kcm_sock * kcm)1098 static void kcm_recv_disable(struct kcm_sock *kcm)
1099 {
1100 struct kcm_mux *mux = kcm->mux;
1101
1102 if (kcm->rx_disabled)
1103 return;
1104
1105 spin_lock_bh(&mux->rx_lock);
1106
1107 kcm->rx_disabled = 1;
1108
1109 /* If a psock is reserved we'll do cleanup in unreserve */
1110 if (!kcm->rx_psock) {
1111 if (kcm->rx_wait) {
1112 list_del(&kcm->wait_rx_list);
1113 /* paired with lockless reads in kcm_rfree() */
1114 WRITE_ONCE(kcm->rx_wait, false);
1115 }
1116
1117 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
1118 }
1119
1120 spin_unlock_bh(&mux->rx_lock);
1121 }
1122
1123 /* kcm sock lock held */
kcm_recv_enable(struct kcm_sock * kcm)1124 static void kcm_recv_enable(struct kcm_sock *kcm)
1125 {
1126 struct kcm_mux *mux = kcm->mux;
1127
1128 if (!kcm->rx_disabled)
1129 return;
1130
1131 spin_lock_bh(&mux->rx_lock);
1132
1133 kcm->rx_disabled = 0;
1134 kcm_rcv_ready(kcm);
1135
1136 spin_unlock_bh(&mux->rx_lock);
1137 }
1138
kcm_setsockopt(struct socket * sock,int level,int optname,sockptr_t optval,unsigned int optlen)1139 static int kcm_setsockopt(struct socket *sock, int level, int optname,
1140 sockptr_t optval, unsigned int optlen)
1141 {
1142 struct kcm_sock *kcm = kcm_sk(sock->sk);
1143 int val, valbool;
1144 int err = 0;
1145
1146 if (level != SOL_KCM)
1147 return -ENOPROTOOPT;
1148
1149 if (optlen < sizeof(int))
1150 return -EINVAL;
1151
1152 if (copy_from_sockptr(&val, optval, sizeof(int)))
1153 return -EFAULT;
1154
1155 valbool = val ? 1 : 0;
1156
1157 switch (optname) {
1158 case KCM_RECV_DISABLE:
1159 lock_sock(&kcm->sk);
1160 if (valbool)
1161 kcm_recv_disable(kcm);
1162 else
1163 kcm_recv_enable(kcm);
1164 release_sock(&kcm->sk);
1165 break;
1166 default:
1167 err = -ENOPROTOOPT;
1168 }
1169
1170 return err;
1171 }
1172
kcm_getsockopt(struct socket * sock,int level,int optname,sockopt_t * opt)1173 static int kcm_getsockopt(struct socket *sock, int level, int optname,
1174 sockopt_t *opt)
1175 {
1176 struct kcm_sock *kcm = kcm_sk(sock->sk);
1177 int val, len;
1178
1179 if (level != SOL_KCM)
1180 return -ENOPROTOOPT;
1181
1182 len = opt->optlen;
1183 if (len < 0)
1184 return -EINVAL;
1185
1186 len = min_t(unsigned int, len, sizeof(int));
1187
1188 switch (optname) {
1189 case KCM_RECV_DISABLE:
1190 val = kcm->rx_disabled;
1191 break;
1192 default:
1193 return -ENOPROTOOPT;
1194 }
1195
1196 opt->optlen = len;
1197 if (copy_to_iter(&val, len, &opt->iter_out) != len)
1198 return -EFAULT;
1199 return 0;
1200 }
1201
init_kcm_sock(struct kcm_sock * kcm,struct kcm_mux * mux)1202 static void init_kcm_sock(struct kcm_sock *kcm, struct kcm_mux *mux)
1203 {
1204 struct kcm_sock *tkcm;
1205 struct list_head *head;
1206 int index = 0;
1207
1208 /* For SOCK_SEQPACKET sock type, datagram_poll checks the sk_state, so
1209 * we set sk_state, otherwise epoll_wait always returns right away with
1210 * EPOLLHUP
1211 */
1212 kcm->sk.sk_state = TCP_ESTABLISHED;
1213
1214 /* Add to mux's kcm sockets list */
1215 kcm->mux = mux;
1216 spin_lock_bh(&mux->lock);
1217
1218 head = &mux->kcm_socks;
1219 list_for_each_entry(tkcm, &mux->kcm_socks, kcm_sock_list) {
1220 if (tkcm->index != index)
1221 break;
1222 head = &tkcm->kcm_sock_list;
1223 index++;
1224 }
1225
1226 list_add(&kcm->kcm_sock_list, head);
1227 kcm->index = index;
1228
1229 mux->kcm_socks_cnt++;
1230 spin_unlock_bh(&mux->lock);
1231
1232 INIT_WORK(&kcm->tx_work, kcm_tx_work);
1233 mutex_init(&kcm->tx_mutex);
1234
1235 spin_lock_bh(&mux->rx_lock);
1236 kcm_rcv_ready(kcm);
1237 spin_unlock_bh(&mux->rx_lock);
1238 }
1239
kcm_attach(struct socket * sock,struct socket * csock,struct bpf_prog * prog)1240 static int kcm_attach(struct socket *sock, struct socket *csock,
1241 struct bpf_prog *prog)
1242 {
1243 struct kcm_sock *kcm = kcm_sk(sock->sk);
1244 struct kcm_mux *mux = kcm->mux;
1245 struct sock *csk;
1246 struct kcm_psock *psock = NULL, *tpsock;
1247 struct list_head *head;
1248 int index = 0;
1249 static const struct strp_callbacks cb = {
1250 .rcv_msg = kcm_rcv_strparser,
1251 .parse_msg = kcm_parse_func_strparser,
1252 .read_sock_done = kcm_read_sock_done,
1253 };
1254 int err = 0;
1255
1256 csk = csock->sk;
1257 if (!csk)
1258 return -EINVAL;
1259
1260 lock_sock(csk);
1261
1262 /* Only allow TCP sockets to be attached for now */
1263 if ((csk->sk_family != AF_INET && csk->sk_family != AF_INET6) ||
1264 csk->sk_protocol != IPPROTO_TCP) {
1265 err = -EOPNOTSUPP;
1266 goto out;
1267 }
1268
1269 /* Don't allow listeners or closed sockets */
1270 if (csk->sk_state == TCP_LISTEN || csk->sk_state == TCP_CLOSE) {
1271 err = -EOPNOTSUPP;
1272 goto out;
1273 }
1274
1275 psock = kmem_cache_zalloc(kcm_psockp, GFP_KERNEL);
1276 if (!psock) {
1277 err = -ENOMEM;
1278 goto out;
1279 }
1280
1281 psock->mux = mux;
1282 psock->sk = csk;
1283 psock->bpf_prog = prog;
1284
1285 write_lock_bh(&csk->sk_callback_lock);
1286
1287 /* Check if sk_user_data is already by KCM or someone else.
1288 * Must be done under lock to prevent race conditions.
1289 */
1290 if (csk->sk_user_data) {
1291 write_unlock_bh(&csk->sk_callback_lock);
1292 kmem_cache_free(kcm_psockp, psock);
1293 err = -EALREADY;
1294 goto out;
1295 }
1296
1297 err = strp_init(&psock->strp, csk, &cb);
1298 if (err) {
1299 write_unlock_bh(&csk->sk_callback_lock);
1300 kmem_cache_free(kcm_psockp, psock);
1301 goto out;
1302 }
1303
1304 psock->save_data_ready = csk->sk_data_ready;
1305 psock->save_write_space = csk->sk_write_space;
1306 psock->save_state_change = csk->sk_state_change;
1307 csk->sk_user_data = psock;
1308 WRITE_ONCE(csk->sk_data_ready, psock_data_ready);
1309 WRITE_ONCE(csk->sk_write_space, psock_write_space);
1310 csk->sk_state_change = psock_state_change;
1311
1312 write_unlock_bh(&csk->sk_callback_lock);
1313
1314 sock_hold(csk);
1315
1316 /* Finished initialization, now add the psock to the MUX. */
1317 spin_lock_bh(&mux->lock);
1318 head = &mux->psocks;
1319 list_for_each_entry(tpsock, &mux->psocks, psock_list) {
1320 if (tpsock->index != index)
1321 break;
1322 head = &tpsock->psock_list;
1323 index++;
1324 }
1325
1326 list_add(&psock->psock_list, head);
1327 psock->index = index;
1328
1329 KCM_STATS_INCR(mux->stats.psock_attach);
1330 mux->psocks_cnt++;
1331 psock_now_avail(psock);
1332 spin_unlock_bh(&mux->lock);
1333
1334 /* Schedule RX work in case there are already bytes queued */
1335 strp_check_rcv(&psock->strp);
1336
1337 out:
1338 release_sock(csk);
1339
1340 return err;
1341 }
1342
kcm_attach_ioctl(struct socket * sock,struct kcm_attach * info)1343 static int kcm_attach_ioctl(struct socket *sock, struct kcm_attach *info)
1344 {
1345 struct socket *csock;
1346 struct bpf_prog *prog;
1347 int err;
1348
1349 csock = sockfd_lookup(info->fd, &err);
1350 if (!csock)
1351 return -ENOENT;
1352
1353 prog = bpf_prog_get_type(info->bpf_fd, BPF_PROG_TYPE_SOCKET_FILTER);
1354 if (IS_ERR(prog)) {
1355 err = PTR_ERR(prog);
1356 goto out;
1357 }
1358
1359 err = kcm_attach(sock, csock, prog);
1360 if (err) {
1361 bpf_prog_put(prog);
1362 goto out;
1363 }
1364
1365 /* Keep reference on file also */
1366
1367 return 0;
1368 out:
1369 sockfd_put(csock);
1370 return err;
1371 }
1372
kcm_unattach(struct kcm_psock * psock)1373 static void kcm_unattach(struct kcm_psock *psock)
1374 {
1375 struct sock *csk = psock->sk;
1376 struct kcm_mux *mux = psock->mux;
1377
1378 lock_sock(csk);
1379
1380 /* Stop getting callbacks from TCP socket. After this there should
1381 * be no way to reserve a kcm for this psock.
1382 */
1383 write_lock_bh(&csk->sk_callback_lock);
1384 csk->sk_user_data = NULL;
1385 WRITE_ONCE(csk->sk_data_ready, psock->save_data_ready);
1386 WRITE_ONCE(csk->sk_write_space, psock->save_write_space);
1387 csk->sk_state_change = psock->save_state_change;
1388 strp_stop(&psock->strp);
1389
1390 if (WARN_ON(psock->rx_kcm)) {
1391 write_unlock_bh(&csk->sk_callback_lock);
1392 release_sock(csk);
1393 return;
1394 }
1395
1396 spin_lock_bh(&mux->rx_lock);
1397
1398 /* Stop receiver activities. After this point psock should not be
1399 * able to get onto ready list either through callbacks or work.
1400 */
1401 if (psock->ready_rx_msg) {
1402 list_del(&psock->psock_ready_list);
1403 kfree_skb(psock->ready_rx_msg);
1404 psock->ready_rx_msg = NULL;
1405 KCM_STATS_INCR(mux->stats.rx_ready_drops);
1406 }
1407
1408 spin_unlock_bh(&mux->rx_lock);
1409
1410 write_unlock_bh(&csk->sk_callback_lock);
1411
1412 /* Call strp_done without sock lock */
1413 release_sock(csk);
1414 strp_done(&psock->strp);
1415 lock_sock(csk);
1416
1417 bpf_prog_put(psock->bpf_prog);
1418
1419 spin_lock_bh(&mux->lock);
1420
1421 aggregate_psock_stats(&psock->stats, &mux->aggregate_psock_stats);
1422 save_strp_stats(&psock->strp, &mux->aggregate_strp_stats);
1423
1424 KCM_STATS_INCR(mux->stats.psock_unattach);
1425
1426 if (psock->tx_kcm) {
1427 /* psock was reserved. Just mark it finished and we will clean
1428 * up in the kcm paths, we need kcm lock which can not be
1429 * acquired here.
1430 */
1431 KCM_STATS_INCR(mux->stats.psock_unattach_rsvd);
1432 spin_unlock_bh(&mux->lock);
1433
1434 /* We are unattaching a socket that is reserved. Abort the
1435 * socket since we may be out of sync in sending on it. We need
1436 * to do this without the mux lock.
1437 */
1438 kcm_abort_tx_psock(psock, EPIPE, false);
1439
1440 spin_lock_bh(&mux->lock);
1441 if (!psock->tx_kcm) {
1442 /* psock now unreserved in window mux was unlocked */
1443 goto no_reserved;
1444 }
1445 psock->done = 1;
1446
1447 /* Commit done before queuing work to process it */
1448 smp_mb();
1449
1450 /* Queue tx work to make sure psock->done is handled */
1451 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
1452 spin_unlock_bh(&mux->lock);
1453 } else {
1454 no_reserved:
1455 if (!psock->tx_stopped)
1456 list_del(&psock->psock_avail_list);
1457 list_del(&psock->psock_list);
1458 mux->psocks_cnt--;
1459 spin_unlock_bh(&mux->lock);
1460
1461 sock_put(csk);
1462 fput(csk->sk_socket->file);
1463 kmem_cache_free(kcm_psockp, psock);
1464 }
1465
1466 release_sock(csk);
1467 }
1468
kcm_unattach_ioctl(struct socket * sock,struct kcm_unattach * info)1469 static int kcm_unattach_ioctl(struct socket *sock, struct kcm_unattach *info)
1470 {
1471 struct kcm_sock *kcm = kcm_sk(sock->sk);
1472 struct kcm_mux *mux = kcm->mux;
1473 struct kcm_psock *psock;
1474 struct socket *csock;
1475 struct sock *csk;
1476 int err;
1477
1478 csock = sockfd_lookup(info->fd, &err);
1479 if (!csock)
1480 return -ENOENT;
1481
1482 csk = csock->sk;
1483 if (!csk) {
1484 err = -EINVAL;
1485 goto out;
1486 }
1487
1488 err = -ENOENT;
1489
1490 spin_lock_bh(&mux->lock);
1491
1492 list_for_each_entry(psock, &mux->psocks, psock_list) {
1493 if (psock->sk != csk)
1494 continue;
1495
1496 /* Found the matching psock */
1497
1498 if (psock->unattaching || WARN_ON(psock->done)) {
1499 err = -EALREADY;
1500 break;
1501 }
1502
1503 psock->unattaching = 1;
1504
1505 spin_unlock_bh(&mux->lock);
1506
1507 /* Lower socket lock should already be held */
1508 kcm_unattach(psock);
1509
1510 err = 0;
1511 goto out;
1512 }
1513
1514 spin_unlock_bh(&mux->lock);
1515
1516 out:
1517 sockfd_put(csock);
1518 return err;
1519 }
1520
1521 static struct proto kcm_proto = {
1522 .name = "KCM",
1523 .owner = THIS_MODULE,
1524 .obj_size = sizeof(struct kcm_sock),
1525 };
1526
1527 /* Clone a kcm socket. */
kcm_clone(struct socket * osock)1528 static struct file *kcm_clone(struct socket *osock)
1529 {
1530 struct socket *newsock;
1531 struct sock *newsk;
1532
1533 newsock = sock_alloc();
1534 if (!newsock)
1535 return ERR_PTR(-ENFILE);
1536
1537 newsock->type = osock->type;
1538 newsock->ops = osock->ops;
1539
1540 __module_get(newsock->ops->owner);
1541
1542 newsk = sk_alloc(sock_net(osock->sk), PF_KCM, GFP_KERNEL,
1543 &kcm_proto, false);
1544 if (!newsk) {
1545 sock_release(newsock);
1546 return ERR_PTR(-ENOMEM);
1547 }
1548 sock_init_data(newsock, newsk);
1549 init_kcm_sock(kcm_sk(newsk), kcm_sk(osock->sk)->mux);
1550
1551 return sock_alloc_file(newsock, 0, osock->sk->sk_prot_creator->name);
1552 }
1553
kcm_ioctl(struct socket * sock,unsigned int cmd,unsigned long arg)1554 static int kcm_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
1555 {
1556 int err;
1557
1558 switch (cmd) {
1559 case SIOCKCMATTACH: {
1560 struct kcm_attach info;
1561
1562 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1563 return -EFAULT;
1564
1565 err = kcm_attach_ioctl(sock, &info);
1566
1567 break;
1568 }
1569 case SIOCKCMUNATTACH: {
1570 struct kcm_unattach info;
1571
1572 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1573 return -EFAULT;
1574
1575 err = kcm_unattach_ioctl(sock, &info);
1576
1577 break;
1578 }
1579 case SIOCKCMCLONE: {
1580 struct kcm_clone info;
1581
1582 FD_PREPARE(fdf, 0, kcm_clone(sock));
1583 if (fdf.err)
1584 return fdf.err;
1585
1586 info.fd = fd_prepare_fd(fdf);
1587 if (copy_to_user((void __user *)arg, &info, sizeof(info)))
1588 return -EFAULT;
1589
1590 fd_publish(fdf);
1591 err = 0;
1592 break;
1593 }
1594 default:
1595 err = -ENOIOCTLCMD;
1596 break;
1597 }
1598
1599 return err;
1600 }
1601
release_mux(struct kcm_mux * mux)1602 static void release_mux(struct kcm_mux *mux)
1603 {
1604 struct kcm_net *knet = mux->knet;
1605 struct kcm_psock *psock, *tmp_psock;
1606
1607 /* Release psocks */
1608 list_for_each_entry_safe(psock, tmp_psock,
1609 &mux->psocks, psock_list) {
1610 if (!WARN_ON(psock->unattaching))
1611 kcm_unattach(psock);
1612 }
1613
1614 if (WARN_ON(mux->psocks_cnt))
1615 return;
1616
1617 __skb_queue_purge(&mux->rx_hold_queue);
1618
1619 mutex_lock(&knet->mutex);
1620 aggregate_mux_stats(&mux->stats, &knet->aggregate_mux_stats);
1621 aggregate_psock_stats(&mux->aggregate_psock_stats,
1622 &knet->aggregate_psock_stats);
1623 aggregate_strp_stats(&mux->aggregate_strp_stats,
1624 &knet->aggregate_strp_stats);
1625 list_del_rcu(&mux->kcm_mux_list);
1626 knet->count--;
1627 mutex_unlock(&knet->mutex);
1628
1629 kfree_rcu(mux, rcu);
1630 }
1631
kcm_done(struct kcm_sock * kcm)1632 static void kcm_done(struct kcm_sock *kcm)
1633 {
1634 struct kcm_mux *mux = kcm->mux;
1635 struct sock *sk = &kcm->sk;
1636 int socks_cnt;
1637
1638 spin_lock_bh(&mux->rx_lock);
1639 if (kcm->rx_psock) {
1640 /* Cleanup in unreserve_rx_kcm */
1641 WARN_ON(kcm->done);
1642 kcm->rx_disabled = 1;
1643 kcm->done = 1;
1644 spin_unlock_bh(&mux->rx_lock);
1645 return;
1646 }
1647
1648 if (kcm->rx_wait) {
1649 list_del(&kcm->wait_rx_list);
1650 /* paired with lockless reads in kcm_rfree() */
1651 WRITE_ONCE(kcm->rx_wait, false);
1652 }
1653 /* Move any pending receive messages to other kcm sockets */
1654 requeue_rx_msgs(mux, &sk->sk_receive_queue);
1655
1656 spin_unlock_bh(&mux->rx_lock);
1657
1658 if (WARN_ON(sk_rmem_alloc_get(sk)))
1659 return;
1660
1661 /* Detach from MUX */
1662 spin_lock_bh(&mux->lock);
1663
1664 list_del(&kcm->kcm_sock_list);
1665 mux->kcm_socks_cnt--;
1666 socks_cnt = mux->kcm_socks_cnt;
1667
1668 spin_unlock_bh(&mux->lock);
1669
1670 if (!socks_cnt) {
1671 /* We are done with the mux now. */
1672 release_mux(mux);
1673 }
1674
1675 WARN_ON(kcm->rx_wait);
1676
1677 sock_put(&kcm->sk);
1678 }
1679
1680 /* Called by kcm_release to close a KCM socket.
1681 * If this is the last KCM socket on the MUX, destroy the MUX.
1682 */
kcm_release(struct socket * sock)1683 static int kcm_release(struct socket *sock)
1684 {
1685 struct sock *sk = sock->sk;
1686 struct kcm_sock *kcm;
1687 struct kcm_mux *mux;
1688 struct kcm_psock *psock;
1689
1690 if (!sk)
1691 return 0;
1692
1693 kcm = kcm_sk(sk);
1694 mux = kcm->mux;
1695
1696 lock_sock(sk);
1697 sock_orphan(sk);
1698 kfree_skb(kcm->seq_skb);
1699
1700 /* Purge queue under lock to avoid race condition with tx_work trying
1701 * to act when queue is nonempty. If tx_work runs after this point
1702 * it will just return.
1703 */
1704 __skb_queue_purge(&sk->sk_write_queue);
1705
1706 release_sock(sk);
1707
1708 spin_lock_bh(&mux->lock);
1709 if (kcm->tx_wait) {
1710 /* Take of tx_wait list, after this point there should be no way
1711 * that a psock will be assigned to this kcm.
1712 */
1713 list_del(&kcm->wait_psock_list);
1714 kcm->tx_wait = false;
1715 }
1716 spin_unlock_bh(&mux->lock);
1717
1718 /* Cancel work. After this point there should be no outside references
1719 * to the kcm socket.
1720 */
1721 disable_work_sync(&kcm->tx_work);
1722
1723 lock_sock(sk);
1724 psock = kcm->tx_psock;
1725 if (psock) {
1726 /* A psock was reserved, so we need to kill it since it
1727 * may already have some bytes queued from a message. We
1728 * need to do this after removing kcm from tx_wait list.
1729 */
1730 kcm_abort_tx_psock(psock, EPIPE, false);
1731 unreserve_psock(kcm);
1732 }
1733 release_sock(sk);
1734
1735 WARN_ON(kcm->tx_wait);
1736 WARN_ON(kcm->tx_psock);
1737
1738 sock->sk = NULL;
1739
1740 kcm_done(kcm);
1741
1742 return 0;
1743 }
1744
1745 static const struct proto_ops kcm_dgram_ops = {
1746 .family = PF_KCM,
1747 .owner = THIS_MODULE,
1748 .release = kcm_release,
1749 .bind = sock_no_bind,
1750 .connect = sock_no_connect,
1751 .socketpair = sock_no_socketpair,
1752 .accept = sock_no_accept,
1753 .getname = sock_no_getname,
1754 .poll = datagram_poll,
1755 .ioctl = kcm_ioctl,
1756 .listen = sock_no_listen,
1757 .shutdown = sock_no_shutdown,
1758 .setsockopt = kcm_setsockopt,
1759 .getsockopt_iter = kcm_getsockopt,
1760 .sendmsg = kcm_sendmsg,
1761 .recvmsg = kcm_recvmsg,
1762 .mmap = sock_no_mmap,
1763 .splice_eof = kcm_splice_eof,
1764 };
1765
1766 static const struct proto_ops kcm_seqpacket_ops = {
1767 .family = PF_KCM,
1768 .owner = THIS_MODULE,
1769 .release = kcm_release,
1770 .bind = sock_no_bind,
1771 .connect = sock_no_connect,
1772 .socketpair = sock_no_socketpair,
1773 .accept = sock_no_accept,
1774 .getname = sock_no_getname,
1775 .poll = datagram_poll,
1776 .ioctl = kcm_ioctl,
1777 .listen = sock_no_listen,
1778 .shutdown = sock_no_shutdown,
1779 .setsockopt = kcm_setsockopt,
1780 .getsockopt_iter = kcm_getsockopt,
1781 .sendmsg = kcm_sendmsg,
1782 .recvmsg = kcm_recvmsg,
1783 .mmap = sock_no_mmap,
1784 .splice_eof = kcm_splice_eof,
1785 .splice_read = kcm_splice_read,
1786 };
1787
1788 /* Create proto operation for kcm sockets */
kcm_create(struct net * net,struct socket * sock,int protocol,int kern)1789 static int kcm_create(struct net *net, struct socket *sock,
1790 int protocol, int kern)
1791 {
1792 struct kcm_net *knet = net_generic(net, kcm_net_id);
1793 struct sock *sk;
1794 struct kcm_mux *mux;
1795
1796 switch (sock->type) {
1797 case SOCK_DGRAM:
1798 sock->ops = &kcm_dgram_ops;
1799 break;
1800 case SOCK_SEQPACKET:
1801 sock->ops = &kcm_seqpacket_ops;
1802 break;
1803 default:
1804 return -ESOCKTNOSUPPORT;
1805 }
1806
1807 if (protocol != KCMPROTO_CONNECTED)
1808 return -EPROTONOSUPPORT;
1809
1810 sk = sk_alloc(net, PF_KCM, GFP_KERNEL, &kcm_proto, kern);
1811 if (!sk)
1812 return -ENOMEM;
1813
1814 /* Allocate a kcm mux, shared between KCM sockets */
1815 mux = kmem_cache_zalloc(kcm_muxp, GFP_KERNEL);
1816 if (!mux) {
1817 sk_free(sk);
1818 return -ENOMEM;
1819 }
1820
1821 spin_lock_init(&mux->lock);
1822 spin_lock_init(&mux->rx_lock);
1823 INIT_LIST_HEAD(&mux->kcm_socks);
1824 INIT_LIST_HEAD(&mux->kcm_rx_waiters);
1825 INIT_LIST_HEAD(&mux->kcm_tx_waiters);
1826
1827 INIT_LIST_HEAD(&mux->psocks);
1828 INIT_LIST_HEAD(&mux->psocks_ready);
1829 INIT_LIST_HEAD(&mux->psocks_avail);
1830
1831 mux->knet = knet;
1832
1833 /* Add new MUX to list */
1834 mutex_lock(&knet->mutex);
1835 list_add_rcu(&mux->kcm_mux_list, &knet->mux_list);
1836 knet->count++;
1837 mutex_unlock(&knet->mutex);
1838
1839 skb_queue_head_init(&mux->rx_hold_queue);
1840
1841 /* Init KCM socket */
1842 sock_init_data(sock, sk);
1843 init_kcm_sock(kcm_sk(sk), mux);
1844
1845 return 0;
1846 }
1847
1848 static const struct net_proto_family kcm_family_ops = {
1849 .family = PF_KCM,
1850 .create = kcm_create,
1851 .owner = THIS_MODULE,
1852 };
1853
kcm_init_net(struct net * net)1854 static __net_init int kcm_init_net(struct net *net)
1855 {
1856 struct kcm_net *knet = net_generic(net, kcm_net_id);
1857
1858 INIT_LIST_HEAD_RCU(&knet->mux_list);
1859 mutex_init(&knet->mutex);
1860
1861 return 0;
1862 }
1863
kcm_exit_net(struct net * net)1864 static __net_exit void kcm_exit_net(struct net *net)
1865 {
1866 struct kcm_net *knet = net_generic(net, kcm_net_id);
1867
1868 /* All KCM sockets should be closed at this point, which should mean
1869 * that all multiplexors and psocks have been destroyed.
1870 */
1871 WARN_ON(!list_empty(&knet->mux_list));
1872
1873 mutex_destroy(&knet->mutex);
1874 }
1875
1876 static struct pernet_operations kcm_net_ops = {
1877 .init = kcm_init_net,
1878 .exit = kcm_exit_net,
1879 .id = &kcm_net_id,
1880 .size = sizeof(struct kcm_net),
1881 };
1882
kcm_init(void)1883 static int __init kcm_init(void)
1884 {
1885 int err = -ENOMEM;
1886
1887 kcm_muxp = KMEM_CACHE(kcm_mux, SLAB_HWCACHE_ALIGN);
1888 if (!kcm_muxp)
1889 goto fail;
1890
1891 kcm_psockp = KMEM_CACHE(kcm_psock, SLAB_HWCACHE_ALIGN);
1892 if (!kcm_psockp)
1893 goto fail;
1894
1895 kcm_wq = create_singlethread_workqueue("kkcmd");
1896 if (!kcm_wq)
1897 goto fail;
1898
1899 err = proto_register(&kcm_proto, 1);
1900 if (err)
1901 goto fail;
1902
1903 err = register_pernet_device(&kcm_net_ops);
1904 if (err)
1905 goto net_ops_fail;
1906
1907 err = sock_register(&kcm_family_ops);
1908 if (err)
1909 goto sock_register_fail;
1910
1911 err = kcm_proc_init();
1912 if (err)
1913 goto proc_init_fail;
1914
1915 return 0;
1916
1917 proc_init_fail:
1918 sock_unregister(PF_KCM);
1919
1920 sock_register_fail:
1921 unregister_pernet_device(&kcm_net_ops);
1922
1923 net_ops_fail:
1924 proto_unregister(&kcm_proto);
1925
1926 fail:
1927 kmem_cache_destroy(kcm_muxp);
1928 kmem_cache_destroy(kcm_psockp);
1929
1930 if (kcm_wq)
1931 destroy_workqueue(kcm_wq);
1932
1933 return err;
1934 }
1935
kcm_exit(void)1936 static void __exit kcm_exit(void)
1937 {
1938 kcm_proc_exit();
1939 sock_unregister(PF_KCM);
1940 unregister_pernet_device(&kcm_net_ops);
1941 proto_unregister(&kcm_proto);
1942 destroy_workqueue(kcm_wq);
1943
1944 kmem_cache_destroy(kcm_muxp);
1945 kmem_cache_destroy(kcm_psockp);
1946 }
1947
1948 module_init(kcm_init);
1949 module_exit(kcm_exit);
1950
1951 MODULE_LICENSE("GPL");
1952 MODULE_DESCRIPTION("KCM (Kernel Connection Multiplexor) sockets");
1953 MODULE_ALIAS_NETPROTO(PF_KCM);
1954