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TOMOYO Linux Cross Reference
Linux/net/kcm/kcmsock.c

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  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/in.h>
 13 #include <linux/kernel.h>
 14 #include <linux/module.h>
 15 #include <linux/net.h>
 16 #include <linux/netdevice.h>
 17 #include <linux/poll.h>
 18 #include <linux/rculist.h>
 19 #include <linux/skbuff.h>
 20 #include <linux/socket.h>
 21 #include <linux/uaccess.h>
 22 #include <linux/workqueue.h>
 23 #include <linux/syscalls.h>
 24 #include <linux/sched/signal.h>
 25 
 26 #include <net/kcm.h>
 27 #include <net/netns/generic.h>
 28 #include <net/sock.h>
 29 #include <uapi/linux/kcm.h>
 30 
 31 unsigned int kcm_net_id;
 32 
 33 static struct kmem_cache *kcm_psockp __read_mostly;
 34 static struct kmem_cache *kcm_muxp __read_mostly;
 35 static struct workqueue_struct *kcm_wq;
 36 
 37 static inline struct kcm_sock *kcm_sk(const struct sock *sk)
 38 {
 39         return (struct kcm_sock *)sk;
 40 }
 41 
 42 static inline struct kcm_tx_msg *kcm_tx_msg(struct sk_buff *skb)
 43 {
 44         return (struct kcm_tx_msg *)skb->cb;
 45 }
 46 
 47 static void report_csk_error(struct sock *csk, int err)
 48 {
 49         csk->sk_err = EPIPE;
 50         csk->sk_error_report(csk);
 51 }
 52 
 53 static void kcm_abort_tx_psock(struct kcm_psock *psock, int err,
 54                                bool wakeup_kcm)
 55 {
 56         struct sock *csk = psock->sk;
 57         struct kcm_mux *mux = psock->mux;
 58 
 59         /* Unrecoverable error in transmit */
 60 
 61         spin_lock_bh(&mux->lock);
 62 
 63         if (psock->tx_stopped) {
 64                 spin_unlock_bh(&mux->lock);
 65                 return;
 66         }
 67 
 68         psock->tx_stopped = 1;
 69         KCM_STATS_INCR(psock->stats.tx_aborts);
 70 
 71         if (!psock->tx_kcm) {
 72                 /* Take off psocks_avail list */
 73                 list_del(&psock->psock_avail_list);
 74         } else if (wakeup_kcm) {
 75                 /* In this case psock is being aborted while outside of
 76                  * write_msgs and psock is reserved. Schedule tx_work
 77                  * to handle the failure there. Need to commit tx_stopped
 78                  * before queuing work.
 79                  */
 80                 smp_mb();
 81 
 82                 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
 83         }
 84 
 85         spin_unlock_bh(&mux->lock);
 86 
 87         /* Report error on lower socket */
 88         report_csk_error(csk, err);
 89 }
 90 
 91 /* RX mux lock held. */
 92 static void kcm_update_rx_mux_stats(struct kcm_mux *mux,
 93                                     struct kcm_psock *psock)
 94 {
 95         STRP_STATS_ADD(mux->stats.rx_bytes,
 96                        psock->strp.stats.bytes -
 97                        psock->saved_rx_bytes);
 98         mux->stats.rx_msgs +=
 99                 psock->strp.stats.msgs - psock->saved_rx_msgs;
100         psock->saved_rx_msgs = psock->strp.stats.msgs;
101         psock->saved_rx_bytes = psock->strp.stats.bytes;
102 }
103 
104 static void kcm_update_tx_mux_stats(struct kcm_mux *mux,
105                                     struct kcm_psock *psock)
106 {
107         KCM_STATS_ADD(mux->stats.tx_bytes,
108                       psock->stats.tx_bytes - psock->saved_tx_bytes);
109         mux->stats.tx_msgs +=
110                 psock->stats.tx_msgs - psock->saved_tx_msgs;
111         psock->saved_tx_msgs = psock->stats.tx_msgs;
112         psock->saved_tx_bytes = psock->stats.tx_bytes;
113 }
114 
115 static int kcm_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
116 
117 /* KCM is ready to receive messages on its queue-- either the KCM is new or
118  * has become unblocked after being blocked on full socket buffer. Queue any
119  * pending ready messages on a psock. RX mux lock held.
120  */
121 static void kcm_rcv_ready(struct kcm_sock *kcm)
122 {
123         struct kcm_mux *mux = kcm->mux;
124         struct kcm_psock *psock;
125         struct sk_buff *skb;
126 
127         if (unlikely(kcm->rx_wait || kcm->rx_psock || kcm->rx_disabled))
128                 return;
129 
130         while (unlikely((skb = __skb_dequeue(&mux->rx_hold_queue)))) {
131                 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
132                         /* Assuming buffer limit has been reached */
133                         skb_queue_head(&mux->rx_hold_queue, skb);
134                         WARN_ON(!sk_rmem_alloc_get(&kcm->sk));
135                         return;
136                 }
137         }
138 
139         while (!list_empty(&mux->psocks_ready)) {
140                 psock = list_first_entry(&mux->psocks_ready, struct kcm_psock,
141                                          psock_ready_list);
142 
143                 if (kcm_queue_rcv_skb(&kcm->sk, psock->ready_rx_msg)) {
144                         /* Assuming buffer limit has been reached */
145                         WARN_ON(!sk_rmem_alloc_get(&kcm->sk));
146                         return;
147                 }
148 
149                 /* Consumed the ready message on the psock. Schedule rx_work to
150                  * get more messages.
151                  */
152                 list_del(&psock->psock_ready_list);
153                 psock->ready_rx_msg = NULL;
154                 /* Commit clearing of ready_rx_msg for queuing work */
155                 smp_mb();
156 
157                 strp_unpause(&psock->strp);
158                 strp_check_rcv(&psock->strp);
159         }
160 
161         /* Buffer limit is okay now, add to ready list */
162         list_add_tail(&kcm->wait_rx_list,
163                       &kcm->mux->kcm_rx_waiters);
164         kcm->rx_wait = true;
165 }
166 
167 static void kcm_rfree(struct sk_buff *skb)
168 {
169         struct sock *sk = skb->sk;
170         struct kcm_sock *kcm = kcm_sk(sk);
171         struct kcm_mux *mux = kcm->mux;
172         unsigned int len = skb->truesize;
173 
174         sk_mem_uncharge(sk, len);
175         atomic_sub(len, &sk->sk_rmem_alloc);
176 
177         /* For reading rx_wait and rx_psock without holding lock */
178         smp_mb__after_atomic();
179 
180         if (!kcm->rx_wait && !kcm->rx_psock &&
181             sk_rmem_alloc_get(sk) < sk->sk_rcvlowat) {
182                 spin_lock_bh(&mux->rx_lock);
183                 kcm_rcv_ready(kcm);
184                 spin_unlock_bh(&mux->rx_lock);
185         }
186 }
187 
188 static int kcm_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
189 {
190         struct sk_buff_head *list = &sk->sk_receive_queue;
191 
192         if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
193                 return -ENOMEM;
194 
195         if (!sk_rmem_schedule(sk, skb, skb->truesize))
196                 return -ENOBUFS;
197 
198         skb->dev = NULL;
199 
200         skb_orphan(skb);
201         skb->sk = sk;
202         skb->destructor = kcm_rfree;
203         atomic_add(skb->truesize, &sk->sk_rmem_alloc);
204         sk_mem_charge(sk, skb->truesize);
205 
206         skb_queue_tail(list, skb);
207 
208         if (!sock_flag(sk, SOCK_DEAD))
209                 sk->sk_data_ready(sk);
210 
211         return 0;
212 }
213 
214 /* Requeue received messages for a kcm socket to other kcm sockets. This is
215  * called with a kcm socket is receive disabled.
216  * RX mux lock held.
217  */
218 static void requeue_rx_msgs(struct kcm_mux *mux, struct sk_buff_head *head)
219 {
220         struct sk_buff *skb;
221         struct kcm_sock *kcm;
222 
223         while ((skb = __skb_dequeue(head))) {
224                 /* Reset destructor to avoid calling kcm_rcv_ready */
225                 skb->destructor = sock_rfree;
226                 skb_orphan(skb);
227 try_again:
228                 if (list_empty(&mux->kcm_rx_waiters)) {
229                         skb_queue_tail(&mux->rx_hold_queue, skb);
230                         continue;
231                 }
232 
233                 kcm = list_first_entry(&mux->kcm_rx_waiters,
234                                        struct kcm_sock, wait_rx_list);
235 
236                 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
237                         /* Should mean socket buffer full */
238                         list_del(&kcm->wait_rx_list);
239                         kcm->rx_wait = false;
240 
241                         /* Commit rx_wait to read in kcm_free */
242                         smp_wmb();
243 
244                         goto try_again;
245                 }
246         }
247 }
248 
249 /* Lower sock lock held */
250 static struct kcm_sock *reserve_rx_kcm(struct kcm_psock *psock,
251                                        struct sk_buff *head)
252 {
253         struct kcm_mux *mux = psock->mux;
254         struct kcm_sock *kcm;
255 
256         WARN_ON(psock->ready_rx_msg);
257 
258         if (psock->rx_kcm)
259                 return psock->rx_kcm;
260 
261         spin_lock_bh(&mux->rx_lock);
262 
263         if (psock->rx_kcm) {
264                 spin_unlock_bh(&mux->rx_lock);
265                 return psock->rx_kcm;
266         }
267 
268         kcm_update_rx_mux_stats(mux, psock);
269 
270         if (list_empty(&mux->kcm_rx_waiters)) {
271                 psock->ready_rx_msg = head;
272                 strp_pause(&psock->strp);
273                 list_add_tail(&psock->psock_ready_list,
274                               &mux->psocks_ready);
275                 spin_unlock_bh(&mux->rx_lock);
276                 return NULL;
277         }
278 
279         kcm = list_first_entry(&mux->kcm_rx_waiters,
280                                struct kcm_sock, wait_rx_list);
281         list_del(&kcm->wait_rx_list);
282         kcm->rx_wait = false;
283 
284         psock->rx_kcm = kcm;
285         kcm->rx_psock = psock;
286 
287         spin_unlock_bh(&mux->rx_lock);
288 
289         return kcm;
290 }
291 
292 static void kcm_done(struct kcm_sock *kcm);
293 
294 static void kcm_done_work(struct work_struct *w)
295 {
296         kcm_done(container_of(w, struct kcm_sock, done_work));
297 }
298 
299 /* Lower sock held */
300 static void unreserve_rx_kcm(struct kcm_psock *psock,
301                              bool rcv_ready)
302 {
303         struct kcm_sock *kcm = psock->rx_kcm;
304         struct kcm_mux *mux = psock->mux;
305 
306         if (!kcm)
307                 return;
308 
309         spin_lock_bh(&mux->rx_lock);
310 
311         psock->rx_kcm = NULL;
312         kcm->rx_psock = NULL;
313 
314         /* Commit kcm->rx_psock before sk_rmem_alloc_get to sync with
315          * kcm_rfree
316          */
317         smp_mb();
318 
319         if (unlikely(kcm->done)) {
320                 spin_unlock_bh(&mux->rx_lock);
321 
322                 /* Need to run kcm_done in a task since we need to qcquire
323                  * callback locks which may already be held here.
324                  */
325                 INIT_WORK(&kcm->done_work, kcm_done_work);
326                 schedule_work(&kcm->done_work);
327                 return;
328         }
329 
330         if (unlikely(kcm->rx_disabled)) {
331                 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
332         } else if (rcv_ready || unlikely(!sk_rmem_alloc_get(&kcm->sk))) {
333                 /* Check for degenerative race with rx_wait that all
334                  * data was dequeued (accounted for in kcm_rfree).
335                  */
336                 kcm_rcv_ready(kcm);
337         }
338         spin_unlock_bh(&mux->rx_lock);
339 }
340 
341 /* Lower sock lock held */
342 static void psock_data_ready(struct sock *sk)
343 {
344         struct kcm_psock *psock;
345 
346         read_lock_bh(&sk->sk_callback_lock);
347 
348         psock = (struct kcm_psock *)sk->sk_user_data;
349         if (likely(psock))
350                 strp_data_ready(&psock->strp);
351 
352         read_unlock_bh(&sk->sk_callback_lock);
353 }
354 
355 /* Called with lower sock held */
356 static void kcm_rcv_strparser(struct strparser *strp, struct sk_buff *skb)
357 {
358         struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
359         struct kcm_sock *kcm;
360 
361 try_queue:
362         kcm = reserve_rx_kcm(psock, skb);
363         if (!kcm) {
364                  /* Unable to reserve a KCM, message is held in psock and strp
365                   * is paused.
366                   */
367                 return;
368         }
369 
370         if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
371                 /* Should mean socket buffer full */
372                 unreserve_rx_kcm(psock, false);
373                 goto try_queue;
374         }
375 }
376 
377 static int kcm_parse_func_strparser(struct strparser *strp, struct sk_buff *skb)
378 {
379         struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
380         struct bpf_prog *prog = psock->bpf_prog;
381 
382         return (*prog->bpf_func)(skb, prog->insnsi);
383 }
384 
385 static int kcm_read_sock_done(struct strparser *strp, int err)
386 {
387         struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
388 
389         unreserve_rx_kcm(psock, true);
390 
391         return err;
392 }
393 
394 static void psock_state_change(struct sock *sk)
395 {
396         /* TCP only does a EPOLLIN for a half close. Do a EPOLLHUP here
397          * since application will normally not poll with EPOLLIN
398          * on the TCP sockets.
399          */
400 
401         report_csk_error(sk, EPIPE);
402 }
403 
404 static void psock_write_space(struct sock *sk)
405 {
406         struct kcm_psock *psock;
407         struct kcm_mux *mux;
408         struct kcm_sock *kcm;
409 
410         read_lock_bh(&sk->sk_callback_lock);
411 
412         psock = (struct kcm_psock *)sk->sk_user_data;
413         if (unlikely(!psock))
414                 goto out;
415         mux = psock->mux;
416 
417         spin_lock_bh(&mux->lock);
418 
419         /* Check if the socket is reserved so someone is waiting for sending. */
420         kcm = psock->tx_kcm;
421         if (kcm && !unlikely(kcm->tx_stopped))
422                 queue_work(kcm_wq, &kcm->tx_work);
423 
424         spin_unlock_bh(&mux->lock);
425 out:
426         read_unlock_bh(&sk->sk_callback_lock);
427 }
428 
429 static void unreserve_psock(struct kcm_sock *kcm);
430 
431 /* kcm sock is locked. */
432 static struct kcm_psock *reserve_psock(struct kcm_sock *kcm)
433 {
434         struct kcm_mux *mux = kcm->mux;
435         struct kcm_psock *psock;
436 
437         psock = kcm->tx_psock;
438 
439         smp_rmb(); /* Must read tx_psock before tx_wait */
440 
441         if (psock) {
442                 WARN_ON(kcm->tx_wait);
443                 if (unlikely(psock->tx_stopped))
444                         unreserve_psock(kcm);
445                 else
446                         return kcm->tx_psock;
447         }
448 
449         spin_lock_bh(&mux->lock);
450 
451         /* Check again under lock to see if psock was reserved for this
452          * psock via psock_unreserve.
453          */
454         psock = kcm->tx_psock;
455         if (unlikely(psock)) {
456                 WARN_ON(kcm->tx_wait);
457                 spin_unlock_bh(&mux->lock);
458                 return kcm->tx_psock;
459         }
460 
461         if (!list_empty(&mux->psocks_avail)) {
462                 psock = list_first_entry(&mux->psocks_avail,
463                                          struct kcm_psock,
464                                          psock_avail_list);
465                 list_del(&psock->psock_avail_list);
466                 if (kcm->tx_wait) {
467                         list_del(&kcm->wait_psock_list);
468                         kcm->tx_wait = false;
469                 }
470                 kcm->tx_psock = psock;
471                 psock->tx_kcm = kcm;
472                 KCM_STATS_INCR(psock->stats.reserved);
473         } else if (!kcm->tx_wait) {
474                 list_add_tail(&kcm->wait_psock_list,
475                               &mux->kcm_tx_waiters);
476                 kcm->tx_wait = true;
477         }
478 
479         spin_unlock_bh(&mux->lock);
480 
481         return psock;
482 }
483 
484 /* mux lock held */
485 static void psock_now_avail(struct kcm_psock *psock)
486 {
487         struct kcm_mux *mux = psock->mux;
488         struct kcm_sock *kcm;
489 
490         if (list_empty(&mux->kcm_tx_waiters)) {
491                 list_add_tail(&psock->psock_avail_list,
492                               &mux->psocks_avail);
493         } else {
494                 kcm = list_first_entry(&mux->kcm_tx_waiters,
495                                        struct kcm_sock,
496                                        wait_psock_list);
497                 list_del(&kcm->wait_psock_list);
498                 kcm->tx_wait = false;
499                 psock->tx_kcm = kcm;
500 
501                 /* Commit before changing tx_psock since that is read in
502                  * reserve_psock before queuing work.
503                  */
504                 smp_mb();
505 
506                 kcm->tx_psock = psock;
507                 KCM_STATS_INCR(psock->stats.reserved);
508                 queue_work(kcm_wq, &kcm->tx_work);
509         }
510 }
511 
512 /* kcm sock is locked. */
513 static void unreserve_psock(struct kcm_sock *kcm)
514 {
515         struct kcm_psock *psock;
516         struct kcm_mux *mux = kcm->mux;
517 
518         spin_lock_bh(&mux->lock);
519 
520         psock = kcm->tx_psock;
521 
522         if (WARN_ON(!psock)) {
523                 spin_unlock_bh(&mux->lock);
524                 return;
525         }
526 
527         smp_rmb(); /* Read tx_psock before tx_wait */
528 
529         kcm_update_tx_mux_stats(mux, psock);
530 
531         WARN_ON(kcm->tx_wait);
532 
533         kcm->tx_psock = NULL;
534         psock->tx_kcm = NULL;
535         KCM_STATS_INCR(psock->stats.unreserved);
536 
537         if (unlikely(psock->tx_stopped)) {
538                 if (psock->done) {
539                         /* Deferred free */
540                         list_del(&psock->psock_list);
541                         mux->psocks_cnt--;
542                         sock_put(psock->sk);
543                         fput(psock->sk->sk_socket->file);
544                         kmem_cache_free(kcm_psockp, psock);
545                 }
546 
547                 /* Don't put back on available list */
548 
549                 spin_unlock_bh(&mux->lock);
550 
551                 return;
552         }
553 
554         psock_now_avail(psock);
555 
556         spin_unlock_bh(&mux->lock);
557 }
558 
559 static void kcm_report_tx_retry(struct kcm_sock *kcm)
560 {
561         struct kcm_mux *mux = kcm->mux;
562 
563         spin_lock_bh(&mux->lock);
564         KCM_STATS_INCR(mux->stats.tx_retries);
565         spin_unlock_bh(&mux->lock);
566 }
567 
568 /* Write any messages ready on the kcm socket.  Called with kcm sock lock
569  * held.  Return bytes actually sent or error.
570  */
571 static int kcm_write_msgs(struct kcm_sock *kcm)
572 {
573         struct sock *sk = &kcm->sk;
574         struct kcm_psock *psock;
575         struct sk_buff *skb, *head;
576         struct kcm_tx_msg *txm;
577         unsigned short fragidx, frag_offset;
578         unsigned int sent, total_sent = 0;
579         int ret = 0;
580 
581         kcm->tx_wait_more = false;
582         psock = kcm->tx_psock;
583         if (unlikely(psock && psock->tx_stopped)) {
584                 /* A reserved psock was aborted asynchronously. Unreserve
585                  * it and we'll retry the message.
586                  */
587                 unreserve_psock(kcm);
588                 kcm_report_tx_retry(kcm);
589                 if (skb_queue_empty(&sk->sk_write_queue))
590                         return 0;
591 
592                 kcm_tx_msg(skb_peek(&sk->sk_write_queue))->sent = 0;
593 
594         } else if (skb_queue_empty(&sk->sk_write_queue)) {
595                 return 0;
596         }
597 
598         head = skb_peek(&sk->sk_write_queue);
599         txm = kcm_tx_msg(head);
600 
601         if (txm->sent) {
602                 /* Send of first skbuff in queue already in progress */
603                 if (WARN_ON(!psock)) {
604                         ret = -EINVAL;
605                         goto out;
606                 }
607                 sent = txm->sent;
608                 frag_offset = txm->frag_offset;
609                 fragidx = txm->fragidx;
610                 skb = txm->frag_skb;
611 
612                 goto do_frag;
613         }
614 
615 try_again:
616         psock = reserve_psock(kcm);
617         if (!psock)
618                 goto out;
619 
620         do {
621                 skb = head;
622                 txm = kcm_tx_msg(head);
623                 sent = 0;
624 
625 do_frag_list:
626                 if (WARN_ON(!skb_shinfo(skb)->nr_frags)) {
627                         ret = -EINVAL;
628                         goto out;
629                 }
630 
631                 for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags;
632                      fragidx++) {
633                         skb_frag_t *frag;
634 
635                         frag_offset = 0;
636 do_frag:
637                         frag = &skb_shinfo(skb)->frags[fragidx];
638                         if (WARN_ON(!frag->size)) {
639                                 ret = -EINVAL;
640                                 goto out;
641                         }
642 
643                         ret = kernel_sendpage(psock->sk->sk_socket,
644                                               frag->page.p,
645                                               frag->page_offset + frag_offset,
646                                               frag->size - frag_offset,
647                                               MSG_DONTWAIT);
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->sent = sent;
654                                         txm->frag_offset = frag_offset;
655                                         txm->fragidx = fragidx;
656                                         txm->frag_skb = skb;
657 
658                                         ret = 0;
659                                         goto out;
660                                 }
661 
662                                 /* Hard failure in sending message, abort this
663                                  * psock since it has lost framing
664                                  * synchonization 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 
671                                 txm->sent = 0;
672                                 kcm_report_tx_retry(kcm);
673                                 ret = 0;
674 
675                                 goto try_again;
676                         }
677 
678                         sent += ret;
679                         frag_offset += ret;
680                         KCM_STATS_ADD(psock->stats.tx_bytes, ret);
681                         if (frag_offset < frag->size) {
682                                 /* Not finished with this frag */
683                                 goto do_frag;
684                         }
685                 }
686 
687                 if (skb == head) {
688                         if (skb_has_frag_list(skb)) {
689                                 skb = skb_shinfo(skb)->frag_list;
690                                 goto do_frag_list;
691                         }
692                 } else if (skb->next) {
693                         skb = skb->next;
694                         goto do_frag_list;
695                 }
696 
697                 /* Successfully sent the whole packet, account for it. */
698                 skb_dequeue(&sk->sk_write_queue);
699                 kfree_skb(head);
700                 sk->sk_wmem_queued -= sent;
701                 total_sent += sent;
702                 KCM_STATS_INCR(psock->stats.tx_msgs);
703         } while ((head = skb_peek(&sk->sk_write_queue)));
704 out:
705         if (!head) {
706                 /* Done with all queued messages. */
707                 WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
708                 unreserve_psock(kcm);
709         }
710 
711         /* Check if write space is available */
712         sk->sk_write_space(sk);
713 
714         return total_sent ? : ret;
715 }
716 
717 static void kcm_tx_work(struct work_struct *w)
718 {
719         struct kcm_sock *kcm = container_of(w, struct kcm_sock, tx_work);
720         struct sock *sk = &kcm->sk;
721         int err;
722 
723         lock_sock(sk);
724 
725         /* Primarily for SOCK_DGRAM sockets, also handle asynchronous tx
726          * aborts
727          */
728         err = kcm_write_msgs(kcm);
729         if (err < 0) {
730                 /* Hard failure in write, report error on KCM socket */
731                 pr_warn("KCM: Hard failure on kcm_write_msgs %d\n", err);
732                 report_csk_error(&kcm->sk, -err);
733                 goto out;
734         }
735 
736         /* Primarily for SOCK_SEQPACKET sockets */
737         if (likely(sk->sk_socket) &&
738             test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
739                 clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
740                 sk->sk_write_space(sk);
741         }
742 
743 out:
744         release_sock(sk);
745 }
746 
747 static void kcm_push(struct kcm_sock *kcm)
748 {
749         if (kcm->tx_wait_more)
750                 kcm_write_msgs(kcm);
751 }
752 
753 static ssize_t kcm_sendpage(struct socket *sock, struct page *page,
754                             int offset, size_t size, int flags)
755 
756 {
757         struct sock *sk = sock->sk;
758         struct kcm_sock *kcm = kcm_sk(sk);
759         struct sk_buff *skb = NULL, *head = NULL;
760         long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
761         bool eor;
762         int err = 0;
763         int i;
764 
765         if (flags & MSG_SENDPAGE_NOTLAST)
766                 flags |= MSG_MORE;
767 
768         /* No MSG_EOR from splice, only look at MSG_MORE */
769         eor = !(flags & MSG_MORE);
770 
771         lock_sock(sk);
772 
773         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
774 
775         err = -EPIPE;
776         if (sk->sk_err)
777                 goto out_error;
778 
779         if (kcm->seq_skb) {
780                 /* Previously opened message */
781                 head = kcm->seq_skb;
782                 skb = kcm_tx_msg(head)->last_skb;
783                 i = skb_shinfo(skb)->nr_frags;
784 
785                 if (skb_can_coalesce(skb, i, page, offset)) {
786                         skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
787                         skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
788                         goto coalesced;
789                 }
790 
791                 if (i >= MAX_SKB_FRAGS) {
792                         struct sk_buff *tskb;
793 
794                         tskb = alloc_skb(0, sk->sk_allocation);
795                         while (!tskb) {
796                                 kcm_push(kcm);
797                                 err = sk_stream_wait_memory(sk, &timeo);
798                                 if (err)
799                                         goto out_error;
800                         }
801 
802                         if (head == skb)
803                                 skb_shinfo(head)->frag_list = tskb;
804                         else
805                                 skb->next = tskb;
806 
807                         skb = tskb;
808                         skb->ip_summed = CHECKSUM_UNNECESSARY;
809                         i = 0;
810                 }
811         } else {
812                 /* Call the sk_stream functions to manage the sndbuf mem. */
813                 if (!sk_stream_memory_free(sk)) {
814                         kcm_push(kcm);
815                         set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
816                         err = sk_stream_wait_memory(sk, &timeo);
817                         if (err)
818                                 goto out_error;
819                 }
820 
821                 head = alloc_skb(0, sk->sk_allocation);
822                 while (!head) {
823                         kcm_push(kcm);
824                         err = sk_stream_wait_memory(sk, &timeo);
825                         if (err)
826                                 goto out_error;
827                 }
828 
829                 skb = head;
830                 i = 0;
831         }
832 
833         get_page(page);
834         skb_fill_page_desc(skb, i, page, offset, size);
835         skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
836 
837 coalesced:
838         skb->len += size;
839         skb->data_len += size;
840         skb->truesize += size;
841         sk->sk_wmem_queued += size;
842         sk_mem_charge(sk, size);
843 
844         if (head != skb) {
845                 head->len += size;
846                 head->data_len += size;
847                 head->truesize += size;
848         }
849 
850         if (eor) {
851                 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
852 
853                 /* Message complete, queue it on send buffer */
854                 __skb_queue_tail(&sk->sk_write_queue, head);
855                 kcm->seq_skb = NULL;
856                 KCM_STATS_INCR(kcm->stats.tx_msgs);
857 
858                 if (flags & MSG_BATCH) {
859                         kcm->tx_wait_more = true;
860                 } else if (kcm->tx_wait_more || not_busy) {
861                         err = kcm_write_msgs(kcm);
862                         if (err < 0) {
863                                 /* We got a hard error in write_msgs but have
864                                  * already queued this message. Report an error
865                                  * in the socket, but don't affect return value
866                                  * from sendmsg
867                                  */
868                                 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
869                                 report_csk_error(&kcm->sk, -err);
870                         }
871                 }
872         } else {
873                 /* Message not complete, save state */
874                 kcm->seq_skb = head;
875                 kcm_tx_msg(head)->last_skb = skb;
876         }
877 
878         KCM_STATS_ADD(kcm->stats.tx_bytes, size);
879 
880         release_sock(sk);
881         return size;
882 
883 out_error:
884         kcm_push(kcm);
885 
886         err = sk_stream_error(sk, flags, err);
887 
888         /* make sure we wake any epoll edge trigger waiter */
889         if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
890                 sk->sk_write_space(sk);
891 
892         release_sock(sk);
893         return err;
894 }
895 
896 static int kcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
897 {
898         struct sock *sk = sock->sk;
899         struct kcm_sock *kcm = kcm_sk(sk);
900         struct sk_buff *skb = NULL, *head = NULL;
901         size_t copy, copied = 0;
902         long timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
903         int eor = (sock->type == SOCK_DGRAM) ?
904                   !(msg->msg_flags & MSG_MORE) : !!(msg->msg_flags & MSG_EOR);
905         int err = -EPIPE;
906 
907         lock_sock(sk);
908 
909         /* Per tcp_sendmsg this should be in poll */
910         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
911 
912         if (sk->sk_err)
913                 goto out_error;
914 
915         if (kcm->seq_skb) {
916                 /* Previously opened message */
917                 head = kcm->seq_skb;
918                 skb = kcm_tx_msg(head)->last_skb;
919                 goto start;
920         }
921 
922         /* Call the sk_stream functions to manage the sndbuf mem. */
923         if (!sk_stream_memory_free(sk)) {
924                 kcm_push(kcm);
925                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
926                 err = sk_stream_wait_memory(sk, &timeo);
927                 if (err)
928                         goto out_error;
929         }
930 
931         if (msg_data_left(msg)) {
932                 /* New message, alloc head skb */
933                 head = alloc_skb(0, sk->sk_allocation);
934                 while (!head) {
935                         kcm_push(kcm);
936                         err = sk_stream_wait_memory(sk, &timeo);
937                         if (err)
938                                 goto out_error;
939 
940                         head = alloc_skb(0, sk->sk_allocation);
941                 }
942 
943                 skb = head;
944 
945                 /* Set ip_summed to CHECKSUM_UNNECESSARY to avoid calling
946                  * csum_and_copy_from_iter from skb_do_copy_data_nocache.
947                  */
948                 skb->ip_summed = CHECKSUM_UNNECESSARY;
949         }
950 
951 start:
952         while (msg_data_left(msg)) {
953                 bool merge = true;
954                 int i = skb_shinfo(skb)->nr_frags;
955                 struct page_frag *pfrag = sk_page_frag(sk);
956 
957                 if (!sk_page_frag_refill(sk, pfrag))
958                         goto wait_for_memory;
959 
960                 if (!skb_can_coalesce(skb, i, pfrag->page,
961                                       pfrag->offset)) {
962                         if (i == MAX_SKB_FRAGS) {
963                                 struct sk_buff *tskb;
964 
965                                 tskb = alloc_skb(0, sk->sk_allocation);
966                                 if (!tskb)
967                                         goto wait_for_memory;
968 
969                                 if (head == skb)
970                                         skb_shinfo(head)->frag_list = tskb;
971                                 else
972                                         skb->next = tskb;
973 
974                                 skb = tskb;
975                                 skb->ip_summed = CHECKSUM_UNNECESSARY;
976                                 continue;
977                         }
978                         merge = false;
979                 }
980 
981                 copy = min_t(int, msg_data_left(msg),
982                              pfrag->size - pfrag->offset);
983 
984                 if (!sk_wmem_schedule(sk, copy))
985                         goto wait_for_memory;
986 
987                 err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
988                                                pfrag->page,
989                                                pfrag->offset,
990                                                copy);
991                 if (err)
992                         goto out_error;
993 
994                 /* Update the skb. */
995                 if (merge) {
996                         skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
997                 } else {
998                         skb_fill_page_desc(skb, i, pfrag->page,
999                                            pfrag->offset, copy);
1000                         get_page(pfrag->page);
1001                 }
1002 
1003                 pfrag->offset += copy;
1004                 copied += copy;
1005                 if (head != skb) {
1006                         head->len += copy;
1007                         head->data_len += copy;
1008                 }
1009 
1010                 continue;
1011 
1012 wait_for_memory:
1013                 kcm_push(kcm);
1014                 err = sk_stream_wait_memory(sk, &timeo);
1015                 if (err)
1016                         goto out_error;
1017         }
1018 
1019         if (eor) {
1020                 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
1021 
1022                 if (head) {
1023                         /* Message complete, queue it on send buffer */
1024                         __skb_queue_tail(&sk->sk_write_queue, head);
1025                         kcm->seq_skb = NULL;
1026                         KCM_STATS_INCR(kcm->stats.tx_msgs);
1027                 }
1028 
1029                 if (msg->msg_flags & MSG_BATCH) {
1030                         kcm->tx_wait_more = true;
1031                 } else if (kcm->tx_wait_more || not_busy) {
1032                         err = kcm_write_msgs(kcm);
1033                         if (err < 0) {
1034                                 /* We got a hard error in write_msgs but have
1035                                  * already queued this message. Report an error
1036                                  * in the socket, but don't affect return value
1037                                  * from sendmsg
1038                                  */
1039                                 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
1040                                 report_csk_error(&kcm->sk, -err);
1041                         }
1042                 }
1043         } else {
1044                 /* Message not complete, save state */
1045 partial_message:
1046                 if (head) {
1047                         kcm->seq_skb = head;
1048                         kcm_tx_msg(head)->last_skb = skb;
1049                 }
1050         }
1051 
1052         KCM_STATS_ADD(kcm->stats.tx_bytes, copied);
1053 
1054         release_sock(sk);
1055         return copied;
1056 
1057 out_error:
1058         kcm_push(kcm);
1059 
1060         if (copied && sock->type == SOCK_SEQPACKET) {
1061                 /* Wrote some bytes before encountering an
1062                  * error, return partial success.
1063                  */
1064                 goto partial_message;
1065         }
1066 
1067         if (head != kcm->seq_skb)
1068                 kfree_skb(head);
1069 
1070         err = sk_stream_error(sk, msg->msg_flags, err);
1071 
1072         /* make sure we wake any epoll edge trigger waiter */
1073         if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
1074                 sk->sk_write_space(sk);
1075 
1076         release_sock(sk);
1077         return err;
1078 }
1079 
1080 static struct sk_buff *kcm_wait_data(struct sock *sk, int flags,
1081                                      long timeo, int *err)
1082 {
1083         struct sk_buff *skb;
1084 
1085         while (!(skb = skb_peek(&sk->sk_receive_queue))) {
1086                 if (sk->sk_err) {
1087                         *err = sock_error(sk);
1088                         return NULL;
1089                 }
1090 
1091                 if (sock_flag(sk, SOCK_DONE))
1092                         return NULL;
1093 
1094                 if ((flags & MSG_DONTWAIT) || !timeo) {
1095                         *err = -EAGAIN;
1096                         return NULL;
1097                 }
1098 
1099                 sk_wait_data(sk, &timeo, NULL);
1100 
1101                 /* Handle signals */
1102                 if (signal_pending(current)) {
1103                         *err = sock_intr_errno(timeo);
1104                         return NULL;
1105                 }
1106         }
1107 
1108         return skb;
1109 }
1110 
1111 static int kcm_recvmsg(struct socket *sock, struct msghdr *msg,
1112                        size_t len, int flags)
1113 {
1114         struct sock *sk = sock->sk;
1115         struct kcm_sock *kcm = kcm_sk(sk);
1116         int err = 0;
1117         long timeo;
1118         struct strp_msg *stm;
1119         int copied = 0;
1120         struct sk_buff *skb;
1121 
1122         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
1123 
1124         lock_sock(sk);
1125 
1126         skb = kcm_wait_data(sk, flags, timeo, &err);
1127         if (!skb)
1128                 goto out;
1129 
1130         /* Okay, have a message on the receive queue */
1131 
1132         stm = strp_msg(skb);
1133 
1134         if (len > stm->full_len)
1135                 len = stm->full_len;
1136 
1137         err = skb_copy_datagram_msg(skb, stm->offset, msg, len);
1138         if (err < 0)
1139                 goto out;
1140 
1141         copied = len;
1142         if (likely(!(flags & MSG_PEEK))) {
1143                 KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1144                 if (copied < stm->full_len) {
1145                         if (sock->type == SOCK_DGRAM) {
1146                                 /* Truncated message */
1147                                 msg->msg_flags |= MSG_TRUNC;
1148                                 goto msg_finished;
1149                         }
1150                         stm->offset += copied;
1151                         stm->full_len -= copied;
1152                 } else {
1153 msg_finished:
1154                         /* Finished with message */
1155                         msg->msg_flags |= MSG_EOR;
1156                         KCM_STATS_INCR(kcm->stats.rx_msgs);
1157                         skb_unlink(skb, &sk->sk_receive_queue);
1158                         kfree_skb(skb);
1159                 }
1160         }
1161 
1162 out:
1163         release_sock(sk);
1164 
1165         return copied ? : err;
1166 }
1167 
1168 static ssize_t kcm_splice_read(struct socket *sock, loff_t *ppos,
1169                                struct pipe_inode_info *pipe, size_t len,
1170                                unsigned int flags)
1171 {
1172         struct sock *sk = sock->sk;
1173         struct kcm_sock *kcm = kcm_sk(sk);
1174         long timeo;
1175         struct strp_msg *stm;
1176         int err = 0;
1177         ssize_t copied;
1178         struct sk_buff *skb;
1179 
1180         /* Only support splice for SOCKSEQPACKET */
1181 
1182         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
1183 
1184         lock_sock(sk);
1185 
1186         skb = kcm_wait_data(sk, flags, timeo, &err);
1187         if (!skb)
1188                 goto err_out;
1189 
1190         /* Okay, have a message on the receive queue */
1191 
1192         stm = strp_msg(skb);
1193 
1194         if (len > stm->full_len)
1195                 len = stm->full_len;
1196 
1197         copied = skb_splice_bits(skb, sk, stm->offset, pipe, len, flags);
1198         if (copied < 0) {
1199                 err = copied;
1200                 goto err_out;
1201         }
1202 
1203         KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1204 
1205         stm->offset += copied;
1206         stm->full_len -= copied;
1207 
1208         /* We have no way to return MSG_EOR. If all the bytes have been
1209          * read we still leave the message in the receive socket buffer.
1210          * A subsequent recvmsg needs to be done to return MSG_EOR and
1211          * finish reading the message.
1212          */
1213 
1214         release_sock(sk);
1215 
1216         return copied;
1217 
1218 err_out:
1219         release_sock(sk);
1220 
1221         return err;
1222 }
1223 
1224 /* kcm sock lock held */
1225 static void kcm_recv_disable(struct kcm_sock *kcm)
1226 {
1227         struct kcm_mux *mux = kcm->mux;
1228 
1229         if (kcm->rx_disabled)
1230                 return;
1231 
1232         spin_lock_bh(&mux->rx_lock);
1233 
1234         kcm->rx_disabled = 1;
1235 
1236         /* If a psock is reserved we'll do cleanup in unreserve */
1237         if (!kcm->rx_psock) {
1238                 if (kcm->rx_wait) {
1239                         list_del(&kcm->wait_rx_list);
1240                         kcm->rx_wait = false;
1241                 }
1242 
1243                 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
1244         }
1245 
1246         spin_unlock_bh(&mux->rx_lock);
1247 }
1248 
1249 /* kcm sock lock held */
1250 static void kcm_recv_enable(struct kcm_sock *kcm)
1251 {
1252         struct kcm_mux *mux = kcm->mux;
1253 
1254         if (!kcm->rx_disabled)
1255                 return;
1256 
1257         spin_lock_bh(&mux->rx_lock);
1258 
1259         kcm->rx_disabled = 0;
1260         kcm_rcv_ready(kcm);
1261 
1262         spin_unlock_bh(&mux->rx_lock);
1263 }
1264 
1265 static int kcm_setsockopt(struct socket *sock, int level, int optname,
1266                           char __user *optval, unsigned int optlen)
1267 {
1268         struct kcm_sock *kcm = kcm_sk(sock->sk);
1269         int val, valbool;
1270         int err = 0;
1271 
1272         if (level != SOL_KCM)
1273                 return -ENOPROTOOPT;
1274 
1275         if (optlen < sizeof(int))
1276                 return -EINVAL;
1277 
1278         if (get_user(val, (int __user *)optval))
1279                 return -EINVAL;
1280 
1281         valbool = val ? 1 : 0;
1282 
1283         switch (optname) {
1284         case KCM_RECV_DISABLE:
1285                 lock_sock(&kcm->sk);
1286                 if (valbool)
1287                         kcm_recv_disable(kcm);
1288                 else
1289                         kcm_recv_enable(kcm);
1290                 release_sock(&kcm->sk);
1291                 break;
1292         default:
1293                 err = -ENOPROTOOPT;
1294         }
1295 
1296         return err;
1297 }
1298 
1299 static int kcm_getsockopt(struct socket *sock, int level, int optname,
1300                           char __user *optval, int __user *optlen)
1301 {
1302         struct kcm_sock *kcm = kcm_sk(sock->sk);
1303         int val, len;
1304 
1305         if (level != SOL_KCM)
1306                 return -ENOPROTOOPT;
1307 
1308         if (get_user(len, optlen))
1309                 return -EFAULT;
1310 
1311         len = min_t(unsigned int, len, sizeof(int));
1312         if (len < 0)
1313                 return -EINVAL;
1314 
1315         switch (optname) {
1316         case KCM_RECV_DISABLE:
1317                 val = kcm->rx_disabled;
1318                 break;
1319         default:
1320                 return -ENOPROTOOPT;
1321         }
1322 
1323         if (put_user(len, optlen))
1324                 return -EFAULT;
1325         if (copy_to_user(optval, &val, len))
1326                 return -EFAULT;
1327         return 0;
1328 }
1329 
1330 static void init_kcm_sock(struct kcm_sock *kcm, struct kcm_mux *mux)
1331 {
1332         struct kcm_sock *tkcm;
1333         struct list_head *head;
1334         int index = 0;
1335 
1336         /* For SOCK_SEQPACKET sock type, datagram_poll checks the sk_state, so
1337          * we set sk_state, otherwise epoll_wait always returns right away with
1338          * EPOLLHUP
1339          */
1340         kcm->sk.sk_state = TCP_ESTABLISHED;
1341 
1342         /* Add to mux's kcm sockets list */
1343         kcm->mux = mux;
1344         spin_lock_bh(&mux->lock);
1345 
1346         head = &mux->kcm_socks;
1347         list_for_each_entry(tkcm, &mux->kcm_socks, kcm_sock_list) {
1348                 if (tkcm->index != index)
1349                         break;
1350                 head = &tkcm->kcm_sock_list;
1351                 index++;
1352         }
1353 
1354         list_add(&kcm->kcm_sock_list, head);
1355         kcm->index = index;
1356 
1357         mux->kcm_socks_cnt++;
1358         spin_unlock_bh(&mux->lock);
1359 
1360         INIT_WORK(&kcm->tx_work, kcm_tx_work);
1361 
1362         spin_lock_bh(&mux->rx_lock);
1363         kcm_rcv_ready(kcm);
1364         spin_unlock_bh(&mux->rx_lock);
1365 }
1366 
1367 static int kcm_attach(struct socket *sock, struct socket *csock,
1368                       struct bpf_prog *prog)
1369 {
1370         struct kcm_sock *kcm = kcm_sk(sock->sk);
1371         struct kcm_mux *mux = kcm->mux;
1372         struct sock *csk;
1373         struct kcm_psock *psock = NULL, *tpsock;
1374         struct list_head *head;
1375         int index = 0;
1376         static const struct strp_callbacks cb = {
1377                 .rcv_msg = kcm_rcv_strparser,
1378                 .parse_msg = kcm_parse_func_strparser,
1379                 .read_sock_done = kcm_read_sock_done,
1380         };
1381         int err = 0;
1382 
1383         csk = csock->sk;
1384         if (!csk)
1385                 return -EINVAL;
1386 
1387         lock_sock(csk);
1388 
1389         /* Only allow TCP sockets to be attached for now */
1390         if ((csk->sk_family != AF_INET && csk->sk_family != AF_INET6) ||
1391             csk->sk_protocol != IPPROTO_TCP) {
1392                 err = -EOPNOTSUPP;
1393                 goto out;
1394         }
1395 
1396         /* Don't allow listeners or closed sockets */
1397         if (csk->sk_state == TCP_LISTEN || csk->sk_state == TCP_CLOSE) {
1398                 err = -EOPNOTSUPP;
1399                 goto out;
1400         }
1401 
1402         psock = kmem_cache_zalloc(kcm_psockp, GFP_KERNEL);
1403         if (!psock) {
1404                 err = -ENOMEM;
1405                 goto out;
1406         }
1407 
1408         psock->mux = mux;
1409         psock->sk = csk;
1410         psock->bpf_prog = prog;
1411 
1412         err = strp_init(&psock->strp, csk, &cb);
1413         if (err) {
1414                 kmem_cache_free(kcm_psockp, psock);
1415                 goto out;
1416         }
1417 
1418         write_lock_bh(&csk->sk_callback_lock);
1419 
1420         /* Check if sk_user_data is aready by KCM or someone else.
1421          * Must be done under lock to prevent race conditions.
1422          */
1423         if (csk->sk_user_data) {
1424                 write_unlock_bh(&csk->sk_callback_lock);
1425                 strp_stop(&psock->strp);
1426                 strp_done(&psock->strp);
1427                 kmem_cache_free(kcm_psockp, psock);
1428                 err = -EALREADY;
1429                 goto out;
1430         }
1431 
1432         psock->save_data_ready = csk->sk_data_ready;
1433         psock->save_write_space = csk->sk_write_space;
1434         psock->save_state_change = csk->sk_state_change;
1435         csk->sk_user_data = psock;
1436         csk->sk_data_ready = psock_data_ready;
1437         csk->sk_write_space = psock_write_space;
1438         csk->sk_state_change = psock_state_change;
1439 
1440         write_unlock_bh(&csk->sk_callback_lock);
1441 
1442         sock_hold(csk);
1443 
1444         /* Finished initialization, now add the psock to the MUX. */
1445         spin_lock_bh(&mux->lock);
1446         head = &mux->psocks;
1447         list_for_each_entry(tpsock, &mux->psocks, psock_list) {
1448                 if (tpsock->index != index)
1449                         break;
1450                 head = &tpsock->psock_list;
1451                 index++;
1452         }
1453 
1454         list_add(&psock->psock_list, head);
1455         psock->index = index;
1456 
1457         KCM_STATS_INCR(mux->stats.psock_attach);
1458         mux->psocks_cnt++;
1459         psock_now_avail(psock);
1460         spin_unlock_bh(&mux->lock);
1461 
1462         /* Schedule RX work in case there are already bytes queued */
1463         strp_check_rcv(&psock->strp);
1464 
1465 out:
1466         release_sock(csk);
1467 
1468         return err;
1469 }
1470 
1471 static int kcm_attach_ioctl(struct socket *sock, struct kcm_attach *info)
1472 {
1473         struct socket *csock;
1474         struct bpf_prog *prog;
1475         int err;
1476 
1477         csock = sockfd_lookup(info->fd, &err);
1478         if (!csock)
1479                 return -ENOENT;
1480 
1481         prog = bpf_prog_get_type(info->bpf_fd, BPF_PROG_TYPE_SOCKET_FILTER);
1482         if (IS_ERR(prog)) {
1483                 err = PTR_ERR(prog);
1484                 goto out;
1485         }
1486 
1487         err = kcm_attach(sock, csock, prog);
1488         if (err) {
1489                 bpf_prog_put(prog);
1490                 goto out;
1491         }
1492 
1493         /* Keep reference on file also */
1494 
1495         return 0;
1496 out:
1497         fput(csock->file);
1498         return err;
1499 }
1500 
1501 static void kcm_unattach(struct kcm_psock *psock)
1502 {
1503         struct sock *csk = psock->sk;
1504         struct kcm_mux *mux = psock->mux;
1505 
1506         lock_sock(csk);
1507 
1508         /* Stop getting callbacks from TCP socket. After this there should
1509          * be no way to reserve a kcm for this psock.
1510          */
1511         write_lock_bh(&csk->sk_callback_lock);
1512         csk->sk_user_data = NULL;
1513         csk->sk_data_ready = psock->save_data_ready;
1514         csk->sk_write_space = psock->save_write_space;
1515         csk->sk_state_change = psock->save_state_change;
1516         strp_stop(&psock->strp);
1517 
1518         if (WARN_ON(psock->rx_kcm)) {
1519                 write_unlock_bh(&csk->sk_callback_lock);
1520                 release_sock(csk);
1521                 return;
1522         }
1523 
1524         spin_lock_bh(&mux->rx_lock);
1525 
1526         /* Stop receiver activities. After this point psock should not be
1527          * able to get onto ready list either through callbacks or work.
1528          */
1529         if (psock->ready_rx_msg) {
1530                 list_del(&psock->psock_ready_list);
1531                 kfree_skb(psock->ready_rx_msg);
1532                 psock->ready_rx_msg = NULL;
1533                 KCM_STATS_INCR(mux->stats.rx_ready_drops);
1534         }
1535 
1536         spin_unlock_bh(&mux->rx_lock);
1537 
1538         write_unlock_bh(&csk->sk_callback_lock);
1539 
1540         /* Call strp_done without sock lock */
1541         release_sock(csk);
1542         strp_done(&psock->strp);
1543         lock_sock(csk);
1544 
1545         bpf_prog_put(psock->bpf_prog);
1546 
1547         spin_lock_bh(&mux->lock);
1548 
1549         aggregate_psock_stats(&psock->stats, &mux->aggregate_psock_stats);
1550         save_strp_stats(&psock->strp, &mux->aggregate_strp_stats);
1551 
1552         KCM_STATS_INCR(mux->stats.psock_unattach);
1553 
1554         if (psock->tx_kcm) {
1555                 /* psock was reserved.  Just mark it finished and we will clean
1556                  * up in the kcm paths, we need kcm lock which can not be
1557                  * acquired here.
1558                  */
1559                 KCM_STATS_INCR(mux->stats.psock_unattach_rsvd);
1560                 spin_unlock_bh(&mux->lock);
1561 
1562                 /* We are unattaching a socket that is reserved. Abort the
1563                  * socket since we may be out of sync in sending on it. We need
1564                  * to do this without the mux lock.
1565                  */
1566                 kcm_abort_tx_psock(psock, EPIPE, false);
1567 
1568                 spin_lock_bh(&mux->lock);
1569                 if (!psock->tx_kcm) {
1570                         /* psock now unreserved in window mux was unlocked */
1571                         goto no_reserved;
1572                 }
1573                 psock->done = 1;
1574 
1575                 /* Commit done before queuing work to process it */
1576                 smp_mb();
1577 
1578                 /* Queue tx work to make sure psock->done is handled */
1579                 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
1580                 spin_unlock_bh(&mux->lock);
1581         } else {
1582 no_reserved:
1583                 if (!psock->tx_stopped)
1584                         list_del(&psock->psock_avail_list);
1585                 list_del(&psock->psock_list);
1586                 mux->psocks_cnt--;
1587                 spin_unlock_bh(&mux->lock);
1588 
1589                 sock_put(csk);
1590                 fput(csk->sk_socket->file);
1591                 kmem_cache_free(kcm_psockp, psock);
1592         }
1593 
1594         release_sock(csk);
1595 }
1596 
1597 static int kcm_unattach_ioctl(struct socket *sock, struct kcm_unattach *info)
1598 {
1599         struct kcm_sock *kcm = kcm_sk(sock->sk);
1600         struct kcm_mux *mux = kcm->mux;
1601         struct kcm_psock *psock;
1602         struct socket *csock;
1603         struct sock *csk;
1604         int err;
1605 
1606         csock = sockfd_lookup(info->fd, &err);
1607         if (!csock)
1608                 return -ENOENT;
1609 
1610         csk = csock->sk;
1611         if (!csk) {
1612                 err = -EINVAL;
1613                 goto out;
1614         }
1615 
1616         err = -ENOENT;
1617 
1618         spin_lock_bh(&mux->lock);
1619 
1620         list_for_each_entry(psock, &mux->psocks, psock_list) {
1621                 if (psock->sk != csk)
1622                         continue;
1623 
1624                 /* Found the matching psock */
1625 
1626                 if (psock->unattaching || WARN_ON(psock->done)) {
1627                         err = -EALREADY;
1628                         break;
1629                 }
1630 
1631                 psock->unattaching = 1;
1632 
1633                 spin_unlock_bh(&mux->lock);
1634 
1635                 /* Lower socket lock should already be held */
1636                 kcm_unattach(psock);
1637 
1638                 err = 0;
1639                 goto out;
1640         }
1641 
1642         spin_unlock_bh(&mux->lock);
1643 
1644 out:
1645         fput(csock->file);
1646         return err;
1647 }
1648 
1649 static struct proto kcm_proto = {
1650         .name   = "KCM",
1651         .owner  = THIS_MODULE,
1652         .obj_size = sizeof(struct kcm_sock),
1653 };
1654 
1655 /* Clone a kcm socket. */
1656 static struct file *kcm_clone(struct socket *osock)
1657 {
1658         struct socket *newsock;
1659         struct sock *newsk;
1660 
1661         newsock = sock_alloc();
1662         if (!newsock)
1663                 return ERR_PTR(-ENFILE);
1664 
1665         newsock->type = osock->type;
1666         newsock->ops = osock->ops;
1667 
1668         __module_get(newsock->ops->owner);
1669 
1670         newsk = sk_alloc(sock_net(osock->sk), PF_KCM, GFP_KERNEL,
1671                          &kcm_proto, false);
1672         if (!newsk) {
1673                 sock_release(newsock);
1674                 return ERR_PTR(-ENOMEM);
1675         }
1676         sock_init_data(newsock, newsk);
1677         init_kcm_sock(kcm_sk(newsk), kcm_sk(osock->sk)->mux);
1678 
1679         return sock_alloc_file(newsock, 0, osock->sk->sk_prot_creator->name);
1680 }
1681 
1682 static int kcm_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
1683 {
1684         int err;
1685 
1686         switch (cmd) {
1687         case SIOCKCMATTACH: {
1688                 struct kcm_attach info;
1689 
1690                 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1691                         return -EFAULT;
1692 
1693                 err = kcm_attach_ioctl(sock, &info);
1694 
1695                 break;
1696         }
1697         case SIOCKCMUNATTACH: {
1698                 struct kcm_unattach info;
1699 
1700                 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1701                         return -EFAULT;
1702 
1703                 err = kcm_unattach_ioctl(sock, &info);
1704 
1705                 break;
1706         }
1707         case SIOCKCMCLONE: {
1708                 struct kcm_clone info;
1709                 struct file *file;
1710 
1711                 info.fd = get_unused_fd_flags(0);
1712                 if (unlikely(info.fd < 0))
1713                         return info.fd;
1714 
1715                 file = kcm_clone(sock);
1716                 if (IS_ERR(file)) {
1717                         put_unused_fd(info.fd);
1718                         return PTR_ERR(file);
1719                 }
1720                 if (copy_to_user((void __user *)arg, &info,
1721                                  sizeof(info))) {
1722                         put_unused_fd(info.fd);
1723                         fput(file);
1724                         return -EFAULT;
1725                 }
1726                 fd_install(info.fd, file);
1727                 err = 0;
1728                 break;
1729         }
1730         default:
1731                 err = -ENOIOCTLCMD;
1732                 break;
1733         }
1734 
1735         return err;
1736 }
1737 
1738 static void free_mux(struct rcu_head *rcu)
1739 {
1740         struct kcm_mux *mux = container_of(rcu,
1741             struct kcm_mux, rcu);
1742 
1743         kmem_cache_free(kcm_muxp, mux);
1744 }
1745 
1746 static void release_mux(struct kcm_mux *mux)
1747 {
1748         struct kcm_net *knet = mux->knet;
1749         struct kcm_psock *psock, *tmp_psock;
1750 
1751         /* Release psocks */
1752         list_for_each_entry_safe(psock, tmp_psock,
1753                                  &mux->psocks, psock_list) {
1754                 if (!WARN_ON(psock->unattaching))
1755                         kcm_unattach(psock);
1756         }
1757 
1758         if (WARN_ON(mux->psocks_cnt))
1759                 return;
1760 
1761         __skb_queue_purge(&mux->rx_hold_queue);
1762 
1763         mutex_lock(&knet->mutex);
1764         aggregate_mux_stats(&mux->stats, &knet->aggregate_mux_stats);
1765         aggregate_psock_stats(&mux->aggregate_psock_stats,
1766                               &knet->aggregate_psock_stats);
1767         aggregate_strp_stats(&mux->aggregate_strp_stats,
1768                              &knet->aggregate_strp_stats);
1769         list_del_rcu(&mux->kcm_mux_list);
1770         knet->count--;
1771         mutex_unlock(&knet->mutex);
1772 
1773         call_rcu(&mux->rcu, free_mux);
1774 }
1775 
1776 static void kcm_done(struct kcm_sock *kcm)
1777 {
1778         struct kcm_mux *mux = kcm->mux;
1779         struct sock *sk = &kcm->sk;
1780         int socks_cnt;
1781 
1782         spin_lock_bh(&mux->rx_lock);
1783         if (kcm->rx_psock) {
1784                 /* Cleanup in unreserve_rx_kcm */
1785                 WARN_ON(kcm->done);
1786                 kcm->rx_disabled = 1;
1787                 kcm->done = 1;
1788                 spin_unlock_bh(&mux->rx_lock);
1789                 return;
1790         }
1791 
1792         if (kcm->rx_wait) {
1793                 list_del(&kcm->wait_rx_list);
1794                 kcm->rx_wait = false;
1795         }
1796         /* Move any pending receive messages to other kcm sockets */
1797         requeue_rx_msgs(mux, &sk->sk_receive_queue);
1798 
1799         spin_unlock_bh(&mux->rx_lock);
1800 
1801         if (WARN_ON(sk_rmem_alloc_get(sk)))
1802                 return;
1803 
1804         /* Detach from MUX */
1805         spin_lock_bh(&mux->lock);
1806 
1807         list_del(&kcm->kcm_sock_list);
1808         mux->kcm_socks_cnt--;
1809         socks_cnt = mux->kcm_socks_cnt;
1810 
1811         spin_unlock_bh(&mux->lock);
1812 
1813         if (!socks_cnt) {
1814                 /* We are done with the mux now. */
1815                 release_mux(mux);
1816         }
1817 
1818         WARN_ON(kcm->rx_wait);
1819 
1820         sock_put(&kcm->sk);
1821 }
1822 
1823 /* Called by kcm_release to close a KCM socket.
1824  * If this is the last KCM socket on the MUX, destroy the MUX.
1825  */
1826 static int kcm_release(struct socket *sock)
1827 {
1828         struct sock *sk = sock->sk;
1829         struct kcm_sock *kcm;
1830         struct kcm_mux *mux;
1831         struct kcm_psock *psock;
1832 
1833         if (!sk)
1834                 return 0;
1835 
1836         kcm = kcm_sk(sk);
1837         mux = kcm->mux;
1838 
1839         sock_orphan(sk);
1840         kfree_skb(kcm->seq_skb);
1841 
1842         lock_sock(sk);
1843         /* Purge queue under lock to avoid race condition with tx_work trying
1844          * to act when queue is nonempty. If tx_work runs after this point
1845          * it will just return.
1846          */
1847         __skb_queue_purge(&sk->sk_write_queue);
1848 
1849         /* Set tx_stopped. This is checked when psock is bound to a kcm and we
1850          * get a writespace callback. This prevents further work being queued
1851          * from the callback (unbinding the psock occurs after canceling work.
1852          */
1853         kcm->tx_stopped = 1;
1854 
1855         release_sock(sk);
1856 
1857         spin_lock_bh(&mux->lock);
1858         if (kcm->tx_wait) {
1859                 /* Take of tx_wait list, after this point there should be no way
1860                  * that a psock will be assigned to this kcm.
1861                  */
1862                 list_del(&kcm->wait_psock_list);
1863                 kcm->tx_wait = false;
1864         }
1865         spin_unlock_bh(&mux->lock);
1866 
1867         /* Cancel work. After this point there should be no outside references
1868          * to the kcm socket.
1869          */
1870         cancel_work_sync(&kcm->tx_work);
1871 
1872         lock_sock(sk);
1873         psock = kcm->tx_psock;
1874         if (psock) {
1875                 /* A psock was reserved, so we need to kill it since it
1876                  * may already have some bytes queued from a message. We
1877                  * need to do this after removing kcm from tx_wait list.
1878                  */
1879                 kcm_abort_tx_psock(psock, EPIPE, false);
1880                 unreserve_psock(kcm);
1881         }
1882         release_sock(sk);
1883 
1884         WARN_ON(kcm->tx_wait);
1885         WARN_ON(kcm->tx_psock);
1886 
1887         sock->sk = NULL;
1888 
1889         kcm_done(kcm);
1890 
1891         return 0;
1892 }
1893 
1894 static const struct proto_ops kcm_dgram_ops = {
1895         .family =       PF_KCM,
1896         .owner =        THIS_MODULE,
1897         .release =      kcm_release,
1898         .bind =         sock_no_bind,
1899         .connect =      sock_no_connect,
1900         .socketpair =   sock_no_socketpair,
1901         .accept =       sock_no_accept,
1902         .getname =      sock_no_getname,
1903         .poll =         datagram_poll,
1904         .ioctl =        kcm_ioctl,
1905         .listen =       sock_no_listen,
1906         .shutdown =     sock_no_shutdown,
1907         .setsockopt =   kcm_setsockopt,
1908         .getsockopt =   kcm_getsockopt,
1909         .sendmsg =      kcm_sendmsg,
1910         .recvmsg =      kcm_recvmsg,
1911         .mmap =         sock_no_mmap,
1912         .sendpage =     kcm_sendpage,
1913 };
1914 
1915 static const struct proto_ops kcm_seqpacket_ops = {
1916         .family =       PF_KCM,
1917         .owner =        THIS_MODULE,
1918         .release =      kcm_release,
1919         .bind =         sock_no_bind,
1920         .connect =      sock_no_connect,
1921         .socketpair =   sock_no_socketpair,
1922         .accept =       sock_no_accept,
1923         .getname =      sock_no_getname,
1924         .poll =         datagram_poll,
1925         .ioctl =        kcm_ioctl,
1926         .listen =       sock_no_listen,
1927         .shutdown =     sock_no_shutdown,
1928         .setsockopt =   kcm_setsockopt,
1929         .getsockopt =   kcm_getsockopt,
1930         .sendmsg =      kcm_sendmsg,
1931         .recvmsg =      kcm_recvmsg,
1932         .mmap =         sock_no_mmap,
1933         .sendpage =     kcm_sendpage,
1934         .splice_read =  kcm_splice_read,
1935 };
1936 
1937 /* Create proto operation for kcm sockets */
1938 static int kcm_create(struct net *net, struct socket *sock,
1939                       int protocol, int kern)
1940 {
1941         struct kcm_net *knet = net_generic(net, kcm_net_id);
1942         struct sock *sk;
1943         struct kcm_mux *mux;
1944 
1945         switch (sock->type) {
1946         case SOCK_DGRAM:
1947                 sock->ops = &kcm_dgram_ops;
1948                 break;
1949         case SOCK_SEQPACKET:
1950                 sock->ops = &kcm_seqpacket_ops;
1951                 break;
1952         default:
1953                 return -ESOCKTNOSUPPORT;
1954         }
1955 
1956         if (protocol != KCMPROTO_CONNECTED)
1957                 return -EPROTONOSUPPORT;
1958 
1959         sk = sk_alloc(net, PF_KCM, GFP_KERNEL, &kcm_proto, kern);
1960         if (!sk)
1961                 return -ENOMEM;
1962 
1963         /* Allocate a kcm mux, shared between KCM sockets */
1964         mux = kmem_cache_zalloc(kcm_muxp, GFP_KERNEL);
1965         if (!mux) {
1966                 sk_free(sk);
1967                 return -ENOMEM;
1968         }
1969 
1970         spin_lock_init(&mux->lock);
1971         spin_lock_init(&mux->rx_lock);
1972         INIT_LIST_HEAD(&mux->kcm_socks);
1973         INIT_LIST_HEAD(&mux->kcm_rx_waiters);
1974         INIT_LIST_HEAD(&mux->kcm_tx_waiters);
1975 
1976         INIT_LIST_HEAD(&mux->psocks);
1977         INIT_LIST_HEAD(&mux->psocks_ready);
1978         INIT_LIST_HEAD(&mux->psocks_avail);
1979 
1980         mux->knet = knet;
1981 
1982         /* Add new MUX to list */
1983         mutex_lock(&knet->mutex);
1984         list_add_rcu(&mux->kcm_mux_list, &knet->mux_list);
1985         knet->count++;
1986         mutex_unlock(&knet->mutex);
1987 
1988         skb_queue_head_init(&mux->rx_hold_queue);
1989 
1990         /* Init KCM socket */
1991         sock_init_data(sock, sk);
1992         init_kcm_sock(kcm_sk(sk), mux);
1993 
1994         return 0;
1995 }
1996 
1997 static const struct net_proto_family kcm_family_ops = {
1998         .family = PF_KCM,
1999         .create = kcm_create,
2000         .owner  = THIS_MODULE,
2001 };
2002 
2003 static __net_init int kcm_init_net(struct net *net)
2004 {
2005         struct kcm_net *knet = net_generic(net, kcm_net_id);
2006 
2007         INIT_LIST_HEAD_RCU(&knet->mux_list);
2008         mutex_init(&knet->mutex);
2009 
2010         return 0;
2011 }
2012 
2013 static __net_exit void kcm_exit_net(struct net *net)
2014 {
2015         struct kcm_net *knet = net_generic(net, kcm_net_id);
2016 
2017         /* All KCM sockets should be closed at this point, which should mean
2018          * that all multiplexors and psocks have been destroyed.
2019          */
2020         WARN_ON(!list_empty(&knet->mux_list));
2021 }
2022 
2023 static struct pernet_operations kcm_net_ops = {
2024         .init = kcm_init_net,
2025         .exit = kcm_exit_net,
2026         .id   = &kcm_net_id,
2027         .size = sizeof(struct kcm_net),
2028 };
2029 
2030 static int __init kcm_init(void)
2031 {
2032         int err = -ENOMEM;
2033 
2034         kcm_muxp = kmem_cache_create("kcm_mux_cache",
2035                                      sizeof(struct kcm_mux), 0,
2036                                      SLAB_HWCACHE_ALIGN, NULL);
2037         if (!kcm_muxp)
2038                 goto fail;
2039 
2040         kcm_psockp = kmem_cache_create("kcm_psock_cache",
2041                                        sizeof(struct kcm_psock), 0,
2042                                         SLAB_HWCACHE_ALIGN, NULL);
2043         if (!kcm_psockp)
2044                 goto fail;
2045 
2046         kcm_wq = create_singlethread_workqueue("kkcmd");
2047         if (!kcm_wq)
2048                 goto fail;
2049 
2050         err = proto_register(&kcm_proto, 1);
2051         if (err)
2052                 goto fail;
2053 
2054         err = register_pernet_device(&kcm_net_ops);
2055         if (err)
2056                 goto net_ops_fail;
2057 
2058         err = sock_register(&kcm_family_ops);
2059         if (err)
2060                 goto sock_register_fail;
2061 
2062         err = kcm_proc_init();
2063         if (err)
2064                 goto proc_init_fail;
2065 
2066         return 0;
2067 
2068 proc_init_fail:
2069         sock_unregister(PF_KCM);
2070 
2071 sock_register_fail:
2072         unregister_pernet_device(&kcm_net_ops);
2073 
2074 net_ops_fail:
2075         proto_unregister(&kcm_proto);
2076 
2077 fail:
2078         kmem_cache_destroy(kcm_muxp);
2079         kmem_cache_destroy(kcm_psockp);
2080 
2081         if (kcm_wq)
2082                 destroy_workqueue(kcm_wq);
2083 
2084         return err;
2085 }
2086 
2087 static void __exit kcm_exit(void)
2088 {
2089         kcm_proc_exit();
2090         sock_unregister(PF_KCM);
2091         unregister_pernet_device(&kcm_net_ops);
2092         proto_unregister(&kcm_proto);
2093         destroy_workqueue(kcm_wq);
2094 
2095         kmem_cache_destroy(kcm_muxp);
2096         kmem_cache_destroy(kcm_psockp);
2097 }
2098 
2099 module_init(kcm_init);
2100 module_exit(kcm_exit);
2101 
2102 MODULE_LICENSE("GPL");
2103 MODULE_ALIAS_NETPROTO(PF_KCM);
2104 

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