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

Version: ~ [ linux-5.5 ] ~ [ linux-5.4.15 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.98 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.167 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.211 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.211 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.81 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 #include <linux/bpf.h>
  2 #include <linux/errno.h>
  3 #include <linux/errqueue.h>
  4 #include <linux/file.h>
  5 #include <linux/in.h>
  6 #include <linux/kernel.h>
  7 #include <linux/module.h>
  8 #include <linux/net.h>
  9 #include <linux/netdevice.h>
 10 #include <linux/poll.h>
 11 #include <linux/rculist.h>
 12 #include <linux/skbuff.h>
 13 #include <linux/socket.h>
 14 #include <linux/uaccess.h>
 15 #include <linux/workqueue.h>
 16 #include <net/kcm.h>
 17 #include <net/netns/generic.h>
 18 #include <net/sock.h>
 19 #include <net/tcp.h>
 20 #include <uapi/linux/kcm.h>
 21 
 22 unsigned int kcm_net_id;
 23 
 24 static struct kmem_cache *kcm_psockp __read_mostly;
 25 static struct kmem_cache *kcm_muxp __read_mostly;
 26 static struct workqueue_struct *kcm_wq;
 27 
 28 static inline struct kcm_sock *kcm_sk(const struct sock *sk)
 29 {
 30         return (struct kcm_sock *)sk;
 31 }
 32 
 33 static inline struct kcm_tx_msg *kcm_tx_msg(struct sk_buff *skb)
 34 {
 35         return (struct kcm_tx_msg *)skb->cb;
 36 }
 37 
 38 static inline struct kcm_rx_msg *kcm_rx_msg(struct sk_buff *skb)
 39 {
 40         return (struct kcm_rx_msg *)((void *)skb->cb +
 41                                      offsetof(struct qdisc_skb_cb, data));
 42 }
 43 
 44 static void report_csk_error(struct sock *csk, int err)
 45 {
 46         csk->sk_err = EPIPE;
 47         csk->sk_error_report(csk);
 48 }
 49 
 50 /* Callback lock held */
 51 static void kcm_abort_rx_psock(struct kcm_psock *psock, int err,
 52                                struct sk_buff *skb)
 53 {
 54         struct sock *csk = psock->sk;
 55 
 56         /* Unrecoverable error in receive */
 57 
 58         del_timer(&psock->rx_msg_timer);
 59 
 60         if (psock->rx_stopped)
 61                 return;
 62 
 63         psock->rx_stopped = 1;
 64         KCM_STATS_INCR(psock->stats.rx_aborts);
 65 
 66         /* Report an error on the lower socket */
 67         report_csk_error(csk, err);
 68 }
 69 
 70 static void kcm_abort_tx_psock(struct kcm_psock *psock, int err,
 71                                bool wakeup_kcm)
 72 {
 73         struct sock *csk = psock->sk;
 74         struct kcm_mux *mux = psock->mux;
 75 
 76         /* Unrecoverable error in transmit */
 77 
 78         spin_lock_bh(&mux->lock);
 79 
 80         if (psock->tx_stopped) {
 81                 spin_unlock_bh(&mux->lock);
 82                 return;
 83         }
 84 
 85         psock->tx_stopped = 1;
 86         KCM_STATS_INCR(psock->stats.tx_aborts);
 87 
 88         if (!psock->tx_kcm) {
 89                 /* Take off psocks_avail list */
 90                 list_del(&psock->psock_avail_list);
 91         } else if (wakeup_kcm) {
 92                 /* In this case psock is being aborted while outside of
 93                  * write_msgs and psock is reserved. Schedule tx_work
 94                  * to handle the failure there. Need to commit tx_stopped
 95                  * before queuing work.
 96                  */
 97                 smp_mb();
 98 
 99                 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
100         }
101 
102         spin_unlock_bh(&mux->lock);
103 
104         /* Report error on lower socket */
105         report_csk_error(csk, err);
106 }
107 
108 /* RX mux lock held. */
109 static void kcm_update_rx_mux_stats(struct kcm_mux *mux,
110                                     struct kcm_psock *psock)
111 {
112         KCM_STATS_ADD(mux->stats.rx_bytes,
113                       psock->stats.rx_bytes - psock->saved_rx_bytes);
114         mux->stats.rx_msgs +=
115                 psock->stats.rx_msgs - psock->saved_rx_msgs;
116         psock->saved_rx_msgs = psock->stats.rx_msgs;
117         psock->saved_rx_bytes = psock->stats.rx_bytes;
118 }
119 
120 static void kcm_update_tx_mux_stats(struct kcm_mux *mux,
121                                     struct kcm_psock *psock)
122 {
123         KCM_STATS_ADD(mux->stats.tx_bytes,
124                       psock->stats.tx_bytes - psock->saved_tx_bytes);
125         mux->stats.tx_msgs +=
126                 psock->stats.tx_msgs - psock->saved_tx_msgs;
127         psock->saved_tx_msgs = psock->stats.tx_msgs;
128         psock->saved_tx_bytes = psock->stats.tx_bytes;
129 }
130 
131 static int kcm_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
132 
133 /* KCM is ready to receive messages on its queue-- either the KCM is new or
134  * has become unblocked after being blocked on full socket buffer. Queue any
135  * pending ready messages on a psock. RX mux lock held.
136  */
137 static void kcm_rcv_ready(struct kcm_sock *kcm)
138 {
139         struct kcm_mux *mux = kcm->mux;
140         struct kcm_psock *psock;
141         struct sk_buff *skb;
142 
143         if (unlikely(kcm->rx_wait || kcm->rx_psock || kcm->rx_disabled))
144                 return;
145 
146         while (unlikely((skb = __skb_dequeue(&mux->rx_hold_queue)))) {
147                 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
148                         /* Assuming buffer limit has been reached */
149                         skb_queue_head(&mux->rx_hold_queue, skb);
150                         WARN_ON(!sk_rmem_alloc_get(&kcm->sk));
151                         return;
152                 }
153         }
154 
155         while (!list_empty(&mux->psocks_ready)) {
156                 psock = list_first_entry(&mux->psocks_ready, struct kcm_psock,
157                                          psock_ready_list);
158 
159                 if (kcm_queue_rcv_skb(&kcm->sk, psock->ready_rx_msg)) {
160                         /* Assuming buffer limit has been reached */
161                         WARN_ON(!sk_rmem_alloc_get(&kcm->sk));
162                         return;
163                 }
164 
165                 /* Consumed the ready message on the psock. Schedule rx_work to
166                  * get more messages.
167                  */
168                 list_del(&psock->psock_ready_list);
169                 psock->ready_rx_msg = NULL;
170 
171                 /* Commit clearing of ready_rx_msg for queuing work */
172                 smp_mb();
173 
174                 queue_work(kcm_wq, &psock->rx_work);
175         }
176 
177         /* Buffer limit is okay now, add to ready list */
178         list_add_tail(&kcm->wait_rx_list,
179                       &kcm->mux->kcm_rx_waiters);
180         kcm->rx_wait = true;
181 }
182 
183 static void kcm_rfree(struct sk_buff *skb)
184 {
185         struct sock *sk = skb->sk;
186         struct kcm_sock *kcm = kcm_sk(sk);
187         struct kcm_mux *mux = kcm->mux;
188         unsigned int len = skb->truesize;
189 
190         sk_mem_uncharge(sk, len);
191         atomic_sub(len, &sk->sk_rmem_alloc);
192 
193         /* For reading rx_wait and rx_psock without holding lock */
194         smp_mb__after_atomic();
195 
196         if (!kcm->rx_wait && !kcm->rx_psock &&
197             sk_rmem_alloc_get(sk) < sk->sk_rcvlowat) {
198                 spin_lock_bh(&mux->rx_lock);
199                 kcm_rcv_ready(kcm);
200                 spin_unlock_bh(&mux->rx_lock);
201         }
202 }
203 
204 static int kcm_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
205 {
206         struct sk_buff_head *list = &sk->sk_receive_queue;
207 
208         if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
209                 return -ENOMEM;
210 
211         if (!sk_rmem_schedule(sk, skb, skb->truesize))
212                 return -ENOBUFS;
213 
214         skb->dev = NULL;
215 
216         skb_orphan(skb);
217         skb->sk = sk;
218         skb->destructor = kcm_rfree;
219         atomic_add(skb->truesize, &sk->sk_rmem_alloc);
220         sk_mem_charge(sk, skb->truesize);
221 
222         skb_queue_tail(list, skb);
223 
224         if (!sock_flag(sk, SOCK_DEAD))
225                 sk->sk_data_ready(sk);
226 
227         return 0;
228 }
229 
230 /* Requeue received messages for a kcm socket to other kcm sockets. This is
231  * called with a kcm socket is receive disabled.
232  * RX mux lock held.
233  */
234 static void requeue_rx_msgs(struct kcm_mux *mux, struct sk_buff_head *head)
235 {
236         struct sk_buff *skb;
237         struct kcm_sock *kcm;
238 
239         while ((skb = __skb_dequeue(head))) {
240                 /* Reset destructor to avoid calling kcm_rcv_ready */
241                 skb->destructor = sock_rfree;
242                 skb_orphan(skb);
243 try_again:
244                 if (list_empty(&mux->kcm_rx_waiters)) {
245                         skb_queue_tail(&mux->rx_hold_queue, skb);
246                         continue;
247                 }
248 
249                 kcm = list_first_entry(&mux->kcm_rx_waiters,
250                                        struct kcm_sock, wait_rx_list);
251 
252                 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
253                         /* Should mean socket buffer full */
254                         list_del(&kcm->wait_rx_list);
255                         kcm->rx_wait = false;
256 
257                         /* Commit rx_wait to read in kcm_free */
258                         smp_wmb();
259 
260                         goto try_again;
261                 }
262         }
263 }
264 
265 /* Lower sock lock held */
266 static struct kcm_sock *reserve_rx_kcm(struct kcm_psock *psock,
267                                        struct sk_buff *head)
268 {
269         struct kcm_mux *mux = psock->mux;
270         struct kcm_sock *kcm;
271 
272         WARN_ON(psock->ready_rx_msg);
273 
274         if (psock->rx_kcm)
275                 return psock->rx_kcm;
276 
277         spin_lock_bh(&mux->rx_lock);
278 
279         if (psock->rx_kcm) {
280                 spin_unlock_bh(&mux->rx_lock);
281                 return psock->rx_kcm;
282         }
283 
284         kcm_update_rx_mux_stats(mux, psock);
285 
286         if (list_empty(&mux->kcm_rx_waiters)) {
287                 psock->ready_rx_msg = head;
288                 list_add_tail(&psock->psock_ready_list,
289                               &mux->psocks_ready);
290                 spin_unlock_bh(&mux->rx_lock);
291                 return NULL;
292         }
293 
294         kcm = list_first_entry(&mux->kcm_rx_waiters,
295                                struct kcm_sock, wait_rx_list);
296         list_del(&kcm->wait_rx_list);
297         kcm->rx_wait = false;
298 
299         psock->rx_kcm = kcm;
300         kcm->rx_psock = psock;
301 
302         spin_unlock_bh(&mux->rx_lock);
303 
304         return kcm;
305 }
306 
307 static void kcm_done(struct kcm_sock *kcm);
308 
309 static void kcm_done_work(struct work_struct *w)
310 {
311         kcm_done(container_of(w, struct kcm_sock, done_work));
312 }
313 
314 /* Lower sock held */
315 static void unreserve_rx_kcm(struct kcm_psock *psock,
316                              bool rcv_ready)
317 {
318         struct kcm_sock *kcm = psock->rx_kcm;
319         struct kcm_mux *mux = psock->mux;
320 
321         if (!kcm)
322                 return;
323 
324         spin_lock_bh(&mux->rx_lock);
325 
326         psock->rx_kcm = NULL;
327         kcm->rx_psock = NULL;
328 
329         /* Commit kcm->rx_psock before sk_rmem_alloc_get to sync with
330          * kcm_rfree
331          */
332         smp_mb();
333 
334         if (unlikely(kcm->done)) {
335                 spin_unlock_bh(&mux->rx_lock);
336 
337                 /* Need to run kcm_done in a task since we need to qcquire
338                  * callback locks which may already be held here.
339                  */
340                 INIT_WORK(&kcm->done_work, kcm_done_work);
341                 schedule_work(&kcm->done_work);
342                 return;
343         }
344 
345         if (unlikely(kcm->rx_disabled)) {
346                 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
347         } else if (rcv_ready || unlikely(!sk_rmem_alloc_get(&kcm->sk))) {
348                 /* Check for degenerative race with rx_wait that all
349                  * data was dequeued (accounted for in kcm_rfree).
350                  */
351                 kcm_rcv_ready(kcm);
352         }
353         spin_unlock_bh(&mux->rx_lock);
354 }
355 
356 static void kcm_start_rx_timer(struct kcm_psock *psock)
357 {
358         if (psock->sk->sk_rcvtimeo)
359                 mod_timer(&psock->rx_msg_timer, psock->sk->sk_rcvtimeo);
360 }
361 
362 /* Macro to invoke filter function. */
363 #define KCM_RUN_FILTER(prog, ctx) \
364         (*prog->bpf_func)(ctx, prog->insnsi)
365 
366 /* Lower socket lock held */
367 static int kcm_tcp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
368                         unsigned int orig_offset, size_t orig_len)
369 {
370         struct kcm_psock *psock = (struct kcm_psock *)desc->arg.data;
371         struct kcm_rx_msg *rxm;
372         struct kcm_sock *kcm;
373         struct sk_buff *head, *skb;
374         size_t eaten = 0, cand_len;
375         ssize_t extra;
376         int err;
377         bool cloned_orig = false;
378 
379         if (psock->ready_rx_msg)
380                 return 0;
381 
382         head = psock->rx_skb_head;
383         if (head) {
384                 /* Message already in progress */
385 
386                 rxm = kcm_rx_msg(head);
387                 if (unlikely(rxm->early_eaten)) {
388                         /* Already some number of bytes on the receive sock
389                          * data saved in rx_skb_head, just indicate they
390                          * are consumed.
391                          */
392                         eaten = orig_len <= rxm->early_eaten ?
393                                 orig_len : rxm->early_eaten;
394                         rxm->early_eaten -= eaten;
395 
396                         return eaten;
397                 }
398 
399                 if (unlikely(orig_offset)) {
400                         /* Getting data with a non-zero offset when a message is
401                          * in progress is not expected. If it does happen, we
402                          * need to clone and pull since we can't deal with
403                          * offsets in the skbs for a message expect in the head.
404                          */
405                         orig_skb = skb_clone(orig_skb, GFP_ATOMIC);
406                         if (!orig_skb) {
407                                 KCM_STATS_INCR(psock->stats.rx_mem_fail);
408                                 desc->error = -ENOMEM;
409                                 return 0;
410                         }
411                         if (!pskb_pull(orig_skb, orig_offset)) {
412                                 KCM_STATS_INCR(psock->stats.rx_mem_fail);
413                                 kfree_skb(orig_skb);
414                                 desc->error = -ENOMEM;
415                                 return 0;
416                         }
417                         cloned_orig = true;
418                         orig_offset = 0;
419                 }
420 
421                 if (!psock->rx_skb_nextp) {
422                         /* We are going to append to the frags_list of head.
423                          * Need to unshare the frag_list.
424                          */
425                         err = skb_unclone(head, GFP_ATOMIC);
426                         if (err) {
427                                 KCM_STATS_INCR(psock->stats.rx_mem_fail);
428                                 desc->error = err;
429                                 return 0;
430                         }
431 
432                         if (unlikely(skb_shinfo(head)->frag_list)) {
433                                 /* We can't append to an sk_buff that already
434                                  * has a frag_list. We create a new head, point
435                                  * the frag_list of that to the old head, and
436                                  * then are able to use the old head->next for
437                                  * appending to the message.
438                                  */
439                                 if (WARN_ON(head->next)) {
440                                         desc->error = -EINVAL;
441                                         return 0;
442                                 }
443 
444                                 skb = alloc_skb(0, GFP_ATOMIC);
445                                 if (!skb) {
446                                         KCM_STATS_INCR(psock->stats.rx_mem_fail);
447                                         desc->error = -ENOMEM;
448                                         return 0;
449                                 }
450                                 skb->len = head->len;
451                                 skb->data_len = head->len;
452                                 skb->truesize = head->truesize;
453                                 *kcm_rx_msg(skb) = *kcm_rx_msg(head);
454                                 psock->rx_skb_nextp = &head->next;
455                                 skb_shinfo(skb)->frag_list = head;
456                                 psock->rx_skb_head = skb;
457                                 head = skb;
458                         } else {
459                                 psock->rx_skb_nextp =
460                                     &skb_shinfo(head)->frag_list;
461                         }
462                 }
463         }
464 
465         while (eaten < orig_len) {
466                 /* Always clone since we will consume something */
467                 skb = skb_clone(orig_skb, GFP_ATOMIC);
468                 if (!skb) {
469                         KCM_STATS_INCR(psock->stats.rx_mem_fail);
470                         desc->error = -ENOMEM;
471                         break;
472                 }
473 
474                 cand_len = orig_len - eaten;
475 
476                 head = psock->rx_skb_head;
477                 if (!head) {
478                         head = skb;
479                         psock->rx_skb_head = head;
480                         /* Will set rx_skb_nextp on next packet if needed */
481                         psock->rx_skb_nextp = NULL;
482                         rxm = kcm_rx_msg(head);
483                         memset(rxm, 0, sizeof(*rxm));
484                         rxm->offset = orig_offset + eaten;
485                 } else {
486                         /* Unclone since we may be appending to an skb that we
487                          * already share a frag_list with.
488                          */
489                         err = skb_unclone(skb, GFP_ATOMIC);
490                         if (err) {
491                                 KCM_STATS_INCR(psock->stats.rx_mem_fail);
492                                 desc->error = err;
493                                 break;
494                         }
495 
496                         rxm = kcm_rx_msg(head);
497                         *psock->rx_skb_nextp = skb;
498                         psock->rx_skb_nextp = &skb->next;
499                         head->data_len += skb->len;
500                         head->len += skb->len;
501                         head->truesize += skb->truesize;
502                 }
503 
504                 if (!rxm->full_len) {
505                         ssize_t len;
506 
507                         len = KCM_RUN_FILTER(psock->bpf_prog, head);
508 
509                         if (!len) {
510                                 /* Need more header to determine length */
511                                 if (!rxm->accum_len) {
512                                         /* Start RX timer for new message */
513                                         kcm_start_rx_timer(psock);
514                                 }
515                                 rxm->accum_len += cand_len;
516                                 eaten += cand_len;
517                                 KCM_STATS_INCR(psock->stats.rx_need_more_hdr);
518                                 WARN_ON(eaten != orig_len);
519                                 break;
520                         } else if (len > psock->sk->sk_rcvbuf) {
521                                 /* Message length exceeds maximum allowed */
522                                 KCM_STATS_INCR(psock->stats.rx_msg_too_big);
523                                 desc->error = -EMSGSIZE;
524                                 psock->rx_skb_head = NULL;
525                                 kcm_abort_rx_psock(psock, EMSGSIZE, head);
526                                 break;
527                         } else if (len <= (ssize_t)head->len -
528                                           skb->len - rxm->offset) {
529                                 /* Length must be into new skb (and also
530                                  * greater than zero)
531                                  */
532                                 KCM_STATS_INCR(psock->stats.rx_bad_hdr_len);
533                                 desc->error = -EPROTO;
534                                 psock->rx_skb_head = NULL;
535                                 kcm_abort_rx_psock(psock, EPROTO, head);
536                                 break;
537                         }
538 
539                         rxm->full_len = len;
540                 }
541 
542                 extra = (ssize_t)(rxm->accum_len + cand_len) - rxm->full_len;
543 
544                 if (extra < 0) {
545                         /* Message not complete yet. */
546                         if (rxm->full_len - rxm->accum_len >
547                             tcp_inq(psock->sk)) {
548                                 /* Don't have the whole messages in the socket
549                                  * buffer. Set psock->rx_need_bytes to wait for
550                                  * the rest of the message. Also, set "early
551                                  * eaten" since we've already buffered the skb
552                                  * but don't consume yet per tcp_read_sock.
553                                  */
554 
555                                 if (!rxm->accum_len) {
556                                         /* Start RX timer for new message */
557                                         kcm_start_rx_timer(psock);
558                                 }
559 
560                                 psock->rx_need_bytes = rxm->full_len -
561                                                        rxm->accum_len;
562                                 rxm->accum_len += cand_len;
563                                 rxm->early_eaten = cand_len;
564                                 KCM_STATS_ADD(psock->stats.rx_bytes, cand_len);
565                                 desc->count = 0; /* Stop reading socket */
566                                 break;
567                         }
568                         rxm->accum_len += cand_len;
569                         eaten += cand_len;
570                         WARN_ON(eaten != orig_len);
571                         break;
572                 }
573 
574                 /* Positive extra indicates ore bytes than needed for the
575                  * message
576                  */
577 
578                 WARN_ON(extra > cand_len);
579 
580                 eaten += (cand_len - extra);
581 
582                 /* Hurray, we have a new message! */
583                 del_timer(&psock->rx_msg_timer);
584                 psock->rx_skb_head = NULL;
585                 KCM_STATS_INCR(psock->stats.rx_msgs);
586 
587 try_queue:
588                 kcm = reserve_rx_kcm(psock, head);
589                 if (!kcm) {
590                         /* Unable to reserve a KCM, message is held in psock. */
591                         break;
592                 }
593 
594                 if (kcm_queue_rcv_skb(&kcm->sk, head)) {
595                         /* Should mean socket buffer full */
596                         unreserve_rx_kcm(psock, false);
597                         goto try_queue;
598                 }
599         }
600 
601         if (cloned_orig)
602                 kfree_skb(orig_skb);
603 
604         KCM_STATS_ADD(psock->stats.rx_bytes, eaten);
605 
606         return eaten;
607 }
608 
609 /* Called with lock held on lower socket */
610 static int psock_tcp_read_sock(struct kcm_psock *psock)
611 {
612         read_descriptor_t desc;
613 
614         desc.arg.data = psock;
615         desc.error = 0;
616         desc.count = 1; /* give more than one skb per call */
617 
618         /* sk should be locked here, so okay to do tcp_read_sock */
619         tcp_read_sock(psock->sk, &desc, kcm_tcp_recv);
620 
621         unreserve_rx_kcm(psock, true);
622 
623         return desc.error;
624 }
625 
626 /* Lower sock lock held */
627 static void psock_tcp_data_ready(struct sock *sk)
628 {
629         struct kcm_psock *psock;
630 
631         read_lock_bh(&sk->sk_callback_lock);
632 
633         psock = (struct kcm_psock *)sk->sk_user_data;
634         if (unlikely(!psock || psock->rx_stopped))
635                 goto out;
636 
637         if (psock->ready_rx_msg)
638                 goto out;
639 
640         if (psock->rx_need_bytes) {
641                 if (tcp_inq(sk) >= psock->rx_need_bytes)
642                         psock->rx_need_bytes = 0;
643                 else
644                         goto out;
645         }
646 
647         if (psock_tcp_read_sock(psock) == -ENOMEM)
648                 queue_delayed_work(kcm_wq, &psock->rx_delayed_work, 0);
649 
650 out:
651         read_unlock_bh(&sk->sk_callback_lock);
652 }
653 
654 static void do_psock_rx_work(struct kcm_psock *psock)
655 {
656         read_descriptor_t rd_desc;
657         struct sock *csk = psock->sk;
658 
659         /* We need the read lock to synchronize with psock_tcp_data_ready. We
660          * need the socket lock for calling tcp_read_sock.
661          */
662         lock_sock(csk);
663         read_lock_bh(&csk->sk_callback_lock);
664 
665         if (unlikely(csk->sk_user_data != psock))
666                 goto out;
667 
668         if (unlikely(psock->rx_stopped))
669                 goto out;
670 
671         if (psock->ready_rx_msg)
672                 goto out;
673 
674         rd_desc.arg.data = psock;
675 
676         if (psock_tcp_read_sock(psock) == -ENOMEM)
677                 queue_delayed_work(kcm_wq, &psock->rx_delayed_work, 0);
678 
679 out:
680         read_unlock_bh(&csk->sk_callback_lock);
681         release_sock(csk);
682 }
683 
684 static void psock_rx_work(struct work_struct *w)
685 {
686         do_psock_rx_work(container_of(w, struct kcm_psock, rx_work));
687 }
688 
689 static void psock_rx_delayed_work(struct work_struct *w)
690 {
691         do_psock_rx_work(container_of(w, struct kcm_psock,
692                                       rx_delayed_work.work));
693 }
694 
695 static void psock_tcp_state_change(struct sock *sk)
696 {
697         /* TCP only does a POLLIN for a half close. Do a POLLHUP here
698          * since application will normally not poll with POLLIN
699          * on the TCP sockets.
700          */
701 
702         report_csk_error(sk, EPIPE);
703 }
704 
705 static void psock_tcp_write_space(struct sock *sk)
706 {
707         struct kcm_psock *psock;
708         struct kcm_mux *mux;
709         struct kcm_sock *kcm;
710 
711         read_lock_bh(&sk->sk_callback_lock);
712 
713         psock = (struct kcm_psock *)sk->sk_user_data;
714         if (unlikely(!psock))
715                 goto out;
716 
717         mux = psock->mux;
718 
719         spin_lock_bh(&mux->lock);
720 
721         /* Check if the socket is reserved so someone is waiting for sending. */
722         kcm = psock->tx_kcm;
723         if (kcm)
724                 queue_work(kcm_wq, &kcm->tx_work);
725 
726         spin_unlock_bh(&mux->lock);
727 out:
728         read_unlock_bh(&sk->sk_callback_lock);
729 }
730 
731 static void unreserve_psock(struct kcm_sock *kcm);
732 
733 /* kcm sock is locked. */
734 static struct kcm_psock *reserve_psock(struct kcm_sock *kcm)
735 {
736         struct kcm_mux *mux = kcm->mux;
737         struct kcm_psock *psock;
738 
739         psock = kcm->tx_psock;
740 
741         smp_rmb(); /* Must read tx_psock before tx_wait */
742 
743         if (psock) {
744                 WARN_ON(kcm->tx_wait);
745                 if (unlikely(psock->tx_stopped))
746                         unreserve_psock(kcm);
747                 else
748                         return kcm->tx_psock;
749         }
750 
751         spin_lock_bh(&mux->lock);
752 
753         /* Check again under lock to see if psock was reserved for this
754          * psock via psock_unreserve.
755          */
756         psock = kcm->tx_psock;
757         if (unlikely(psock)) {
758                 WARN_ON(kcm->tx_wait);
759                 spin_unlock_bh(&mux->lock);
760                 return kcm->tx_psock;
761         }
762 
763         if (!list_empty(&mux->psocks_avail)) {
764                 psock = list_first_entry(&mux->psocks_avail,
765                                          struct kcm_psock,
766                                          psock_avail_list);
767                 list_del(&psock->psock_avail_list);
768                 if (kcm->tx_wait) {
769                         list_del(&kcm->wait_psock_list);
770                         kcm->tx_wait = false;
771                 }
772                 kcm->tx_psock = psock;
773                 psock->tx_kcm = kcm;
774                 KCM_STATS_INCR(psock->stats.reserved);
775         } else if (!kcm->tx_wait) {
776                 list_add_tail(&kcm->wait_psock_list,
777                               &mux->kcm_tx_waiters);
778                 kcm->tx_wait = true;
779         }
780 
781         spin_unlock_bh(&mux->lock);
782 
783         return psock;
784 }
785 
786 /* mux lock held */
787 static void psock_now_avail(struct kcm_psock *psock)
788 {
789         struct kcm_mux *mux = psock->mux;
790         struct kcm_sock *kcm;
791 
792         if (list_empty(&mux->kcm_tx_waiters)) {
793                 list_add_tail(&psock->psock_avail_list,
794                               &mux->psocks_avail);
795         } else {
796                 kcm = list_first_entry(&mux->kcm_tx_waiters,
797                                        struct kcm_sock,
798                                        wait_psock_list);
799                 list_del(&kcm->wait_psock_list);
800                 kcm->tx_wait = false;
801                 psock->tx_kcm = kcm;
802 
803                 /* Commit before changing tx_psock since that is read in
804                  * reserve_psock before queuing work.
805                  */
806                 smp_mb();
807 
808                 kcm->tx_psock = psock;
809                 KCM_STATS_INCR(psock->stats.reserved);
810                 queue_work(kcm_wq, &kcm->tx_work);
811         }
812 }
813 
814 /* kcm sock is locked. */
815 static void unreserve_psock(struct kcm_sock *kcm)
816 {
817         struct kcm_psock *psock;
818         struct kcm_mux *mux = kcm->mux;
819 
820         spin_lock_bh(&mux->lock);
821 
822         psock = kcm->tx_psock;
823 
824         if (WARN_ON(!psock)) {
825                 spin_unlock_bh(&mux->lock);
826                 return;
827         }
828 
829         smp_rmb(); /* Read tx_psock before tx_wait */
830 
831         kcm_update_tx_mux_stats(mux, psock);
832 
833         WARN_ON(kcm->tx_wait);
834 
835         kcm->tx_psock = NULL;
836         psock->tx_kcm = NULL;
837         KCM_STATS_INCR(psock->stats.unreserved);
838 
839         if (unlikely(psock->tx_stopped)) {
840                 if (psock->done) {
841                         /* Deferred free */
842                         list_del(&psock->psock_list);
843                         mux->psocks_cnt--;
844                         sock_put(psock->sk);
845                         fput(psock->sk->sk_socket->file);
846                         kmem_cache_free(kcm_psockp, psock);
847                 }
848 
849                 /* Don't put back on available list */
850 
851                 spin_unlock_bh(&mux->lock);
852 
853                 return;
854         }
855 
856         psock_now_avail(psock);
857 
858         spin_unlock_bh(&mux->lock);
859 }
860 
861 static void kcm_report_tx_retry(struct kcm_sock *kcm)
862 {
863         struct kcm_mux *mux = kcm->mux;
864 
865         spin_lock_bh(&mux->lock);
866         KCM_STATS_INCR(mux->stats.tx_retries);
867         spin_unlock_bh(&mux->lock);
868 }
869 
870 /* Write any messages ready on the kcm socket.  Called with kcm sock lock
871  * held.  Return bytes actually sent or error.
872  */
873 static int kcm_write_msgs(struct kcm_sock *kcm)
874 {
875         struct sock *sk = &kcm->sk;
876         struct kcm_psock *psock;
877         struct sk_buff *skb, *head;
878         struct kcm_tx_msg *txm;
879         unsigned short fragidx, frag_offset;
880         unsigned int sent, total_sent = 0;
881         int ret = 0;
882 
883         kcm->tx_wait_more = false;
884         psock = kcm->tx_psock;
885         if (unlikely(psock && psock->tx_stopped)) {
886                 /* A reserved psock was aborted asynchronously. Unreserve
887                  * it and we'll retry the message.
888                  */
889                 unreserve_psock(kcm);
890                 kcm_report_tx_retry(kcm);
891                 if (skb_queue_empty(&sk->sk_write_queue))
892                         return 0;
893 
894                 kcm_tx_msg(skb_peek(&sk->sk_write_queue))->sent = 0;
895 
896         } else if (skb_queue_empty(&sk->sk_write_queue)) {
897                 return 0;
898         }
899 
900         head = skb_peek(&sk->sk_write_queue);
901         txm = kcm_tx_msg(head);
902 
903         if (txm->sent) {
904                 /* Send of first skbuff in queue already in progress */
905                 if (WARN_ON(!psock)) {
906                         ret = -EINVAL;
907                         goto out;
908                 }
909                 sent = txm->sent;
910                 frag_offset = txm->frag_offset;
911                 fragidx = txm->fragidx;
912                 skb = txm->frag_skb;
913 
914                 goto do_frag;
915         }
916 
917 try_again:
918         psock = reserve_psock(kcm);
919         if (!psock)
920                 goto out;
921 
922         do {
923                 skb = head;
924                 txm = kcm_tx_msg(head);
925                 sent = 0;
926 
927 do_frag_list:
928                 if (WARN_ON(!skb_shinfo(skb)->nr_frags)) {
929                         ret = -EINVAL;
930                         goto out;
931                 }
932 
933                 for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags;
934                      fragidx++) {
935                         skb_frag_t *frag;
936 
937                         frag_offset = 0;
938 do_frag:
939                         frag = &skb_shinfo(skb)->frags[fragidx];
940                         if (WARN_ON(!frag->size)) {
941                                 ret = -EINVAL;
942                                 goto out;
943                         }
944 
945                         ret = kernel_sendpage(psock->sk->sk_socket,
946                                               frag->page.p,
947                                               frag->page_offset + frag_offset,
948                                               frag->size - frag_offset,
949                                               MSG_DONTWAIT);
950                         if (ret <= 0) {
951                                 if (ret == -EAGAIN) {
952                                         /* Save state to try again when there's
953                                          * write space on the socket
954                                          */
955                                         txm->sent = sent;
956                                         txm->frag_offset = frag_offset;
957                                         txm->fragidx = fragidx;
958                                         txm->frag_skb = skb;
959 
960                                         ret = 0;
961                                         goto out;
962                                 }
963 
964                                 /* Hard failure in sending message, abort this
965                                  * psock since it has lost framing
966                                  * synchonization and retry sending the
967                                  * message from the beginning.
968                                  */
969                                 kcm_abort_tx_psock(psock, ret ? -ret : EPIPE,
970                                                    true);
971                                 unreserve_psock(kcm);
972 
973                                 txm->sent = 0;
974                                 kcm_report_tx_retry(kcm);
975                                 ret = 0;
976 
977                                 goto try_again;
978                         }
979 
980                         sent += ret;
981                         frag_offset += ret;
982                         KCM_STATS_ADD(psock->stats.tx_bytes, ret);
983                         if (frag_offset < frag->size) {
984                                 /* Not finished with this frag */
985                                 goto do_frag;
986                         }
987                 }
988 
989                 if (skb == head) {
990                         if (skb_has_frag_list(skb)) {
991                                 skb = skb_shinfo(skb)->frag_list;
992                                 goto do_frag_list;
993                         }
994                 } else if (skb->next) {
995                         skb = skb->next;
996                         goto do_frag_list;
997                 }
998 
999                 /* Successfully sent the whole packet, account for it. */
1000                 skb_dequeue(&sk->sk_write_queue);
1001                 kfree_skb(head);
1002                 sk->sk_wmem_queued -= sent;
1003                 total_sent += sent;
1004                 KCM_STATS_INCR(psock->stats.tx_msgs);
1005         } while ((head = skb_peek(&sk->sk_write_queue)));
1006 out:
1007         if (!head) {
1008                 /* Done with all queued messages. */
1009                 WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
1010                 unreserve_psock(kcm);
1011         }
1012 
1013         /* Check if write space is available */
1014         sk->sk_write_space(sk);
1015 
1016         return total_sent ? : ret;
1017 }
1018 
1019 static void kcm_tx_work(struct work_struct *w)
1020 {
1021         struct kcm_sock *kcm = container_of(w, struct kcm_sock, tx_work);
1022         struct sock *sk = &kcm->sk;
1023         int err;
1024 
1025         lock_sock(sk);
1026 
1027         /* Primarily for SOCK_DGRAM sockets, also handle asynchronous tx
1028          * aborts
1029          */
1030         err = kcm_write_msgs(kcm);
1031         if (err < 0) {
1032                 /* Hard failure in write, report error on KCM socket */
1033                 pr_warn("KCM: Hard failure on kcm_write_msgs %d\n", err);
1034                 report_csk_error(&kcm->sk, -err);
1035                 goto out;
1036         }
1037 
1038         /* Primarily for SOCK_SEQPACKET sockets */
1039         if (likely(sk->sk_socket) &&
1040             test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
1041                 clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
1042                 sk->sk_write_space(sk);
1043         }
1044 
1045 out:
1046         release_sock(sk);
1047 }
1048 
1049 static void kcm_push(struct kcm_sock *kcm)
1050 {
1051         if (kcm->tx_wait_more)
1052                 kcm_write_msgs(kcm);
1053 }
1054 
1055 static ssize_t kcm_sendpage(struct socket *sock, struct page *page,
1056                             int offset, size_t size, int flags)
1057 
1058 {
1059         struct sock *sk = sock->sk;
1060         struct kcm_sock *kcm = kcm_sk(sk);
1061         struct sk_buff *skb = NULL, *head = NULL;
1062         long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
1063         bool eor;
1064         int err = 0;
1065         int i;
1066 
1067         if (flags & MSG_SENDPAGE_NOTLAST)
1068                 flags |= MSG_MORE;
1069 
1070         /* No MSG_EOR from splice, only look at MSG_MORE */
1071         eor = !(flags & MSG_MORE);
1072 
1073         lock_sock(sk);
1074 
1075         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
1076 
1077         err = -EPIPE;
1078         if (sk->sk_err)
1079                 goto out_error;
1080 
1081         if (kcm->seq_skb) {
1082                 /* Previously opened message */
1083                 head = kcm->seq_skb;
1084                 skb = kcm_tx_msg(head)->last_skb;
1085                 i = skb_shinfo(skb)->nr_frags;
1086 
1087                 if (skb_can_coalesce(skb, i, page, offset)) {
1088                         skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
1089                         skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
1090                         goto coalesced;
1091                 }
1092 
1093                 if (i >= MAX_SKB_FRAGS) {
1094                         struct sk_buff *tskb;
1095 
1096                         tskb = alloc_skb(0, sk->sk_allocation);
1097                         while (!tskb) {
1098                                 kcm_push(kcm);
1099                                 err = sk_stream_wait_memory(sk, &timeo);
1100                                 if (err)
1101                                         goto out_error;
1102                         }
1103 
1104                         if (head == skb)
1105                                 skb_shinfo(head)->frag_list = tskb;
1106                         else
1107                                 skb->next = tskb;
1108 
1109                         skb = tskb;
1110                         skb->ip_summed = CHECKSUM_UNNECESSARY;
1111                         i = 0;
1112                 }
1113         } else {
1114                 /* Call the sk_stream functions to manage the sndbuf mem. */
1115                 if (!sk_stream_memory_free(sk)) {
1116                         kcm_push(kcm);
1117                         set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
1118                         err = sk_stream_wait_memory(sk, &timeo);
1119                         if (err)
1120                                 goto out_error;
1121                 }
1122 
1123                 head = alloc_skb(0, sk->sk_allocation);
1124                 while (!head) {
1125                         kcm_push(kcm);
1126                         err = sk_stream_wait_memory(sk, &timeo);
1127                         if (err)
1128                                 goto out_error;
1129                 }
1130 
1131                 skb = head;
1132                 i = 0;
1133         }
1134 
1135         get_page(page);
1136         skb_fill_page_desc(skb, i, page, offset, size);
1137         skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
1138 
1139 coalesced:
1140         skb->len += size;
1141         skb->data_len += size;
1142         skb->truesize += size;
1143         sk->sk_wmem_queued += size;
1144         sk_mem_charge(sk, size);
1145 
1146         if (head != skb) {
1147                 head->len += size;
1148                 head->data_len += size;
1149                 head->truesize += size;
1150         }
1151 
1152         if (eor) {
1153                 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
1154 
1155                 /* Message complete, queue it on send buffer */
1156                 __skb_queue_tail(&sk->sk_write_queue, head);
1157                 kcm->seq_skb = NULL;
1158                 KCM_STATS_INCR(kcm->stats.tx_msgs);
1159 
1160                 if (flags & MSG_BATCH) {
1161                         kcm->tx_wait_more = true;
1162                 } else if (kcm->tx_wait_more || not_busy) {
1163                         err = kcm_write_msgs(kcm);
1164                         if (err < 0) {
1165                                 /* We got a hard error in write_msgs but have
1166                                  * already queued this message. Report an error
1167                                  * in the socket, but don't affect return value
1168                                  * from sendmsg
1169                                  */
1170                                 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
1171                                 report_csk_error(&kcm->sk, -err);
1172                         }
1173                 }
1174         } else {
1175                 /* Message not complete, save state */
1176                 kcm->seq_skb = head;
1177                 kcm_tx_msg(head)->last_skb = skb;
1178         }
1179 
1180         KCM_STATS_ADD(kcm->stats.tx_bytes, size);
1181 
1182         release_sock(sk);
1183         return size;
1184 
1185 out_error:
1186         kcm_push(kcm);
1187 
1188         err = sk_stream_error(sk, flags, err);
1189 
1190         /* make sure we wake any epoll edge trigger waiter */
1191         if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
1192                 sk->sk_write_space(sk);
1193 
1194         release_sock(sk);
1195         return err;
1196 }
1197 
1198 static int kcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
1199 {
1200         struct sock *sk = sock->sk;
1201         struct kcm_sock *kcm = kcm_sk(sk);
1202         struct sk_buff *skb = NULL, *head = NULL;
1203         size_t copy, copied = 0;
1204         long timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
1205         int eor = (sock->type == SOCK_DGRAM) ?
1206                   !(msg->msg_flags & MSG_MORE) : !!(msg->msg_flags & MSG_EOR);
1207         int err = -EPIPE;
1208 
1209         lock_sock(sk);
1210 
1211         /* Per tcp_sendmsg this should be in poll */
1212         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
1213 
1214         if (sk->sk_err)
1215                 goto out_error;
1216 
1217         if (kcm->seq_skb) {
1218                 /* Previously opened message */
1219                 head = kcm->seq_skb;
1220                 skb = kcm_tx_msg(head)->last_skb;
1221                 goto start;
1222         }
1223 
1224         /* Call the sk_stream functions to manage the sndbuf mem. */
1225         if (!sk_stream_memory_free(sk)) {
1226                 kcm_push(kcm);
1227                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
1228                 err = sk_stream_wait_memory(sk, &timeo);
1229                 if (err)
1230                         goto out_error;
1231         }
1232 
1233         /* New message, alloc head skb */
1234         head = alloc_skb(0, sk->sk_allocation);
1235         while (!head) {
1236                 kcm_push(kcm);
1237                 err = sk_stream_wait_memory(sk, &timeo);
1238                 if (err)
1239                         goto out_error;
1240 
1241                 head = alloc_skb(0, sk->sk_allocation);
1242         }
1243 
1244         skb = head;
1245 
1246         /* Set ip_summed to CHECKSUM_UNNECESSARY to avoid calling
1247          * csum_and_copy_from_iter from skb_do_copy_data_nocache.
1248          */
1249         skb->ip_summed = CHECKSUM_UNNECESSARY;
1250 
1251 start:
1252         while (msg_data_left(msg)) {
1253                 bool merge = true;
1254                 int i = skb_shinfo(skb)->nr_frags;
1255                 struct page_frag *pfrag = sk_page_frag(sk);
1256 
1257                 if (!sk_page_frag_refill(sk, pfrag))
1258                         goto wait_for_memory;
1259 
1260                 if (!skb_can_coalesce(skb, i, pfrag->page,
1261                                       pfrag->offset)) {
1262                         if (i == MAX_SKB_FRAGS) {
1263                                 struct sk_buff *tskb;
1264 
1265                                 tskb = alloc_skb(0, sk->sk_allocation);
1266                                 if (!tskb)
1267                                         goto wait_for_memory;
1268 
1269                                 if (head == skb)
1270                                         skb_shinfo(head)->frag_list = tskb;
1271                                 else
1272                                         skb->next = tskb;
1273 
1274                                 skb = tskb;
1275                                 skb->ip_summed = CHECKSUM_UNNECESSARY;
1276                                 continue;
1277                         }
1278                         merge = false;
1279                 }
1280 
1281                 copy = min_t(int, msg_data_left(msg),
1282                              pfrag->size - pfrag->offset);
1283 
1284                 if (!sk_wmem_schedule(sk, copy))
1285                         goto wait_for_memory;
1286 
1287                 err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
1288                                                pfrag->page,
1289                                                pfrag->offset,
1290                                                copy);
1291                 if (err)
1292                         goto out_error;
1293 
1294                 /* Update the skb. */
1295                 if (merge) {
1296                         skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1297                 } else {
1298                         skb_fill_page_desc(skb, i, pfrag->page,
1299                                            pfrag->offset, copy);
1300                         get_page(pfrag->page);
1301                 }
1302 
1303                 pfrag->offset += copy;
1304                 copied += copy;
1305                 if (head != skb) {
1306                         head->len += copy;
1307                         head->data_len += copy;
1308                 }
1309 
1310                 continue;
1311 
1312 wait_for_memory:
1313                 kcm_push(kcm);
1314                 err = sk_stream_wait_memory(sk, &timeo);
1315                 if (err)
1316                         goto out_error;
1317         }
1318 
1319         if (eor) {
1320                 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
1321 
1322                 /* Message complete, queue it on send buffer */
1323                 __skb_queue_tail(&sk->sk_write_queue, head);
1324                 kcm->seq_skb = NULL;
1325                 KCM_STATS_INCR(kcm->stats.tx_msgs);
1326 
1327                 if (msg->msg_flags & MSG_BATCH) {
1328                         kcm->tx_wait_more = true;
1329                 } else if (kcm->tx_wait_more || not_busy) {
1330                         err = kcm_write_msgs(kcm);
1331                         if (err < 0) {
1332                                 /* We got a hard error in write_msgs but have
1333                                  * already queued this message. Report an error
1334                                  * in the socket, but don't affect return value
1335                                  * from sendmsg
1336                                  */
1337                                 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
1338                                 report_csk_error(&kcm->sk, -err);
1339                         }
1340                 }
1341         } else {
1342                 /* Message not complete, save state */
1343 partial_message:
1344                 kcm->seq_skb = head;
1345                 kcm_tx_msg(head)->last_skb = skb;
1346         }
1347 
1348         KCM_STATS_ADD(kcm->stats.tx_bytes, copied);
1349 
1350         release_sock(sk);
1351         return copied;
1352 
1353 out_error:
1354         kcm_push(kcm);
1355 
1356         if (copied && sock->type == SOCK_SEQPACKET) {
1357                 /* Wrote some bytes before encountering an
1358                  * error, return partial success.
1359                  */
1360                 goto partial_message;
1361         }
1362 
1363         if (head != kcm->seq_skb)
1364                 kfree_skb(head);
1365 
1366         err = sk_stream_error(sk, msg->msg_flags, err);
1367 
1368         /* make sure we wake any epoll edge trigger waiter */
1369         if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
1370                 sk->sk_write_space(sk);
1371 
1372         release_sock(sk);
1373         return err;
1374 }
1375 
1376 static struct sk_buff *kcm_wait_data(struct sock *sk, int flags,
1377                                      long timeo, int *err)
1378 {
1379         struct sk_buff *skb;
1380 
1381         while (!(skb = skb_peek(&sk->sk_receive_queue))) {
1382                 if (sk->sk_err) {
1383                         *err = sock_error(sk);
1384                         return NULL;
1385                 }
1386 
1387                 if (sock_flag(sk, SOCK_DONE))
1388                         return NULL;
1389 
1390                 if ((flags & MSG_DONTWAIT) || !timeo) {
1391                         *err = -EAGAIN;
1392                         return NULL;
1393                 }
1394 
1395                 sk_wait_data(sk, &timeo, NULL);
1396 
1397                 /* Handle signals */
1398                 if (signal_pending(current)) {
1399                         *err = sock_intr_errno(timeo);
1400                         return NULL;
1401                 }
1402         }
1403 
1404         return skb;
1405 }
1406 
1407 static int kcm_recvmsg(struct socket *sock, struct msghdr *msg,
1408                        size_t len, int flags)
1409 {
1410         struct sock *sk = sock->sk;
1411         struct kcm_sock *kcm = kcm_sk(sk);
1412         int err = 0;
1413         long timeo;
1414         struct kcm_rx_msg *rxm;
1415         int copied = 0;
1416         struct sk_buff *skb;
1417 
1418         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
1419 
1420         lock_sock(sk);
1421 
1422         skb = kcm_wait_data(sk, flags, timeo, &err);
1423         if (!skb)
1424                 goto out;
1425 
1426         /* Okay, have a message on the receive queue */
1427 
1428         rxm = kcm_rx_msg(skb);
1429 
1430         if (len > rxm->full_len)
1431                 len = rxm->full_len;
1432 
1433         err = skb_copy_datagram_msg(skb, rxm->offset, msg, len);
1434         if (err < 0)
1435                 goto out;
1436 
1437         copied = len;
1438         if (likely(!(flags & MSG_PEEK))) {
1439                 KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1440                 if (copied < rxm->full_len) {
1441                         if (sock->type == SOCK_DGRAM) {
1442                                 /* Truncated message */
1443                                 msg->msg_flags |= MSG_TRUNC;
1444                                 goto msg_finished;
1445                         }
1446                         rxm->offset += copied;
1447                         rxm->full_len -= copied;
1448                 } else {
1449 msg_finished:
1450                         /* Finished with message */
1451                         msg->msg_flags |= MSG_EOR;
1452                         KCM_STATS_INCR(kcm->stats.rx_msgs);
1453                         skb_unlink(skb, &sk->sk_receive_queue);
1454                         kfree_skb(skb);
1455                 }
1456         }
1457 
1458 out:
1459         release_sock(sk);
1460 
1461         return copied ? : err;
1462 }
1463 
1464 static ssize_t kcm_sock_splice(struct sock *sk,
1465                                struct pipe_inode_info *pipe,
1466                                struct splice_pipe_desc *spd)
1467 {
1468         int ret;
1469 
1470         release_sock(sk);
1471         ret = splice_to_pipe(pipe, spd);
1472         lock_sock(sk);
1473 
1474         return ret;
1475 }
1476 
1477 static ssize_t kcm_splice_read(struct socket *sock, loff_t *ppos,
1478                                struct pipe_inode_info *pipe, size_t len,
1479                                unsigned int flags)
1480 {
1481         struct sock *sk = sock->sk;
1482         struct kcm_sock *kcm = kcm_sk(sk);
1483         long timeo;
1484         struct kcm_rx_msg *rxm;
1485         int err = 0;
1486         size_t copied;
1487         struct sk_buff *skb;
1488 
1489         /* Only support splice for SOCKSEQPACKET */
1490 
1491         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
1492 
1493         lock_sock(sk);
1494 
1495         skb = kcm_wait_data(sk, flags, timeo, &err);
1496         if (!skb)
1497                 goto err_out;
1498 
1499         /* Okay, have a message on the receive queue */
1500 
1501         rxm = kcm_rx_msg(skb);
1502 
1503         if (len > rxm->full_len)
1504                 len = rxm->full_len;
1505 
1506         copied = skb_splice_bits(skb, sk, rxm->offset, pipe, len, flags,
1507                                  kcm_sock_splice);
1508         if (copied < 0) {
1509                 err = copied;
1510                 goto err_out;
1511         }
1512 
1513         KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1514 
1515         rxm->offset += copied;
1516         rxm->full_len -= copied;
1517 
1518         /* We have no way to return MSG_EOR. If all the bytes have been
1519          * read we still leave the message in the receive socket buffer.
1520          * A subsequent recvmsg needs to be done to return MSG_EOR and
1521          * finish reading the message.
1522          */
1523 
1524         release_sock(sk);
1525 
1526         return copied;
1527 
1528 err_out:
1529         release_sock(sk);
1530 
1531         return err;
1532 }
1533 
1534 /* kcm sock lock held */
1535 static void kcm_recv_disable(struct kcm_sock *kcm)
1536 {
1537         struct kcm_mux *mux = kcm->mux;
1538 
1539         if (kcm->rx_disabled)
1540                 return;
1541 
1542         spin_lock_bh(&mux->rx_lock);
1543 
1544         kcm->rx_disabled = 1;
1545 
1546         /* If a psock is reserved we'll do cleanup in unreserve */
1547         if (!kcm->rx_psock) {
1548                 if (kcm->rx_wait) {
1549                         list_del(&kcm->wait_rx_list);
1550                         kcm->rx_wait = false;
1551                 }
1552 
1553                 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
1554         }
1555 
1556         spin_unlock_bh(&mux->rx_lock);
1557 }
1558 
1559 /* kcm sock lock held */
1560 static void kcm_recv_enable(struct kcm_sock *kcm)
1561 {
1562         struct kcm_mux *mux = kcm->mux;
1563 
1564         if (!kcm->rx_disabled)
1565                 return;
1566 
1567         spin_lock_bh(&mux->rx_lock);
1568 
1569         kcm->rx_disabled = 0;
1570         kcm_rcv_ready(kcm);
1571 
1572         spin_unlock_bh(&mux->rx_lock);
1573 }
1574 
1575 static int kcm_setsockopt(struct socket *sock, int level, int optname,
1576                           char __user *optval, unsigned int optlen)
1577 {
1578         struct kcm_sock *kcm = kcm_sk(sock->sk);
1579         int val, valbool;
1580         int err = 0;
1581 
1582         if (level != SOL_KCM)
1583                 return -ENOPROTOOPT;
1584 
1585         if (optlen < sizeof(int))
1586                 return -EINVAL;
1587 
1588         if (get_user(val, (int __user *)optval))
1589                 return -EINVAL;
1590 
1591         valbool = val ? 1 : 0;
1592 
1593         switch (optname) {
1594         case KCM_RECV_DISABLE:
1595                 lock_sock(&kcm->sk);
1596                 if (valbool)
1597                         kcm_recv_disable(kcm);
1598                 else
1599                         kcm_recv_enable(kcm);
1600                 release_sock(&kcm->sk);
1601                 break;
1602         default:
1603                 err = -ENOPROTOOPT;
1604         }
1605 
1606         return err;
1607 }
1608 
1609 static int kcm_getsockopt(struct socket *sock, int level, int optname,
1610                           char __user *optval, int __user *optlen)
1611 {
1612         struct kcm_sock *kcm = kcm_sk(sock->sk);
1613         int val, len;
1614 
1615         if (level != SOL_KCM)
1616                 return -ENOPROTOOPT;
1617 
1618         if (get_user(len, optlen))
1619                 return -EFAULT;
1620 
1621         len = min_t(unsigned int, len, sizeof(int));
1622         if (len < 0)
1623                 return -EINVAL;
1624 
1625         switch (optname) {
1626         case KCM_RECV_DISABLE:
1627                 val = kcm->rx_disabled;
1628                 break;
1629         default:
1630                 return -ENOPROTOOPT;
1631         }
1632 
1633         if (put_user(len, optlen))
1634                 return -EFAULT;
1635         if (copy_to_user(optval, &val, len))
1636                 return -EFAULT;
1637         return 0;
1638 }
1639 
1640 static void init_kcm_sock(struct kcm_sock *kcm, struct kcm_mux *mux)
1641 {
1642         struct kcm_sock *tkcm;
1643         struct list_head *head;
1644         int index = 0;
1645 
1646         /* For SOCK_SEQPACKET sock type, datagram_poll checks the sk_state, so
1647          * we set sk_state, otherwise epoll_wait always returns right away with
1648          * POLLHUP
1649          */
1650         kcm->sk.sk_state = TCP_ESTABLISHED;
1651 
1652         /* Add to mux's kcm sockets list */
1653         kcm->mux = mux;
1654         spin_lock_bh(&mux->lock);
1655 
1656         head = &mux->kcm_socks;
1657         list_for_each_entry(tkcm, &mux->kcm_socks, kcm_sock_list) {
1658                 if (tkcm->index != index)
1659                         break;
1660                 head = &tkcm->kcm_sock_list;
1661                 index++;
1662         }
1663 
1664         list_add(&kcm->kcm_sock_list, head);
1665         kcm->index = index;
1666 
1667         mux->kcm_socks_cnt++;
1668         spin_unlock_bh(&mux->lock);
1669 
1670         INIT_WORK(&kcm->tx_work, kcm_tx_work);
1671 
1672         spin_lock_bh(&mux->rx_lock);
1673         kcm_rcv_ready(kcm);
1674         spin_unlock_bh(&mux->rx_lock);
1675 }
1676 
1677 static void kcm_rx_msg_timeout(unsigned long arg)
1678 {
1679         struct kcm_psock *psock = (struct kcm_psock *)arg;
1680 
1681         /* Message assembly timed out */
1682         KCM_STATS_INCR(psock->stats.rx_msg_timeouts);
1683         kcm_abort_rx_psock(psock, ETIMEDOUT, NULL);
1684 }
1685 
1686 static int kcm_attach(struct socket *sock, struct socket *csock,
1687                       struct bpf_prog *prog)
1688 {
1689         struct kcm_sock *kcm = kcm_sk(sock->sk);
1690         struct kcm_mux *mux = kcm->mux;
1691         struct sock *csk;
1692         struct kcm_psock *psock = NULL, *tpsock;
1693         struct list_head *head;
1694         int index = 0;
1695 
1696         if (csock->ops->family != PF_INET &&
1697             csock->ops->family != PF_INET6)
1698                 return -EINVAL;
1699 
1700         csk = csock->sk;
1701         if (!csk)
1702                 return -EINVAL;
1703 
1704         /* Only support TCP for now */
1705         if (csk->sk_protocol != IPPROTO_TCP)
1706                 return -EINVAL;
1707 
1708         psock = kmem_cache_zalloc(kcm_psockp, GFP_KERNEL);
1709         if (!psock)
1710                 return -ENOMEM;
1711 
1712         psock->mux = mux;
1713         psock->sk = csk;
1714         psock->bpf_prog = prog;
1715 
1716         setup_timer(&psock->rx_msg_timer, kcm_rx_msg_timeout,
1717                     (unsigned long)psock);
1718 
1719         INIT_WORK(&psock->rx_work, psock_rx_work);
1720         INIT_DELAYED_WORK(&psock->rx_delayed_work, psock_rx_delayed_work);
1721 
1722         sock_hold(csk);
1723 
1724         write_lock_bh(&csk->sk_callback_lock);
1725         psock->save_data_ready = csk->sk_data_ready;
1726         psock->save_write_space = csk->sk_write_space;
1727         psock->save_state_change = csk->sk_state_change;
1728         csk->sk_user_data = psock;
1729         csk->sk_data_ready = psock_tcp_data_ready;
1730         csk->sk_write_space = psock_tcp_write_space;
1731         csk->sk_state_change = psock_tcp_state_change;
1732         write_unlock_bh(&csk->sk_callback_lock);
1733 
1734         /* Finished initialization, now add the psock to the MUX. */
1735         spin_lock_bh(&mux->lock);
1736         head = &mux->psocks;
1737         list_for_each_entry(tpsock, &mux->psocks, psock_list) {
1738                 if (tpsock->index != index)
1739                         break;
1740                 head = &tpsock->psock_list;
1741                 index++;
1742         }
1743 
1744         list_add(&psock->psock_list, head);
1745         psock->index = index;
1746 
1747         KCM_STATS_INCR(mux->stats.psock_attach);
1748         mux->psocks_cnt++;
1749         psock_now_avail(psock);
1750         spin_unlock_bh(&mux->lock);
1751 
1752         /* Schedule RX work in case there are already bytes queued */
1753         queue_work(kcm_wq, &psock->rx_work);
1754 
1755         return 0;
1756 }
1757 
1758 static int kcm_attach_ioctl(struct socket *sock, struct kcm_attach *info)
1759 {
1760         struct socket *csock;
1761         struct bpf_prog *prog;
1762         int err;
1763 
1764         csock = sockfd_lookup(info->fd, &err);
1765         if (!csock)
1766                 return -ENOENT;
1767 
1768         prog = bpf_prog_get(info->bpf_fd);
1769         if (IS_ERR(prog)) {
1770                 err = PTR_ERR(prog);
1771                 goto out;
1772         }
1773 
1774         if (prog->type != BPF_PROG_TYPE_SOCKET_FILTER) {
1775                 bpf_prog_put(prog);
1776                 err = -EINVAL;
1777                 goto out;
1778         }
1779 
1780         err = kcm_attach(sock, csock, prog);
1781         if (err) {
1782                 bpf_prog_put(prog);
1783                 goto out;
1784         }
1785 
1786         /* Keep reference on file also */
1787 
1788         return 0;
1789 out:
1790         fput(csock->file);
1791         return err;
1792 }
1793 
1794 static void kcm_unattach(struct kcm_psock *psock)
1795 {
1796         struct sock *csk = psock->sk;
1797         struct kcm_mux *mux = psock->mux;
1798 
1799         /* Stop getting callbacks from TCP socket. After this there should
1800          * be no way to reserve a kcm for this psock.
1801          */
1802         write_lock_bh(&csk->sk_callback_lock);
1803         csk->sk_user_data = NULL;
1804         csk->sk_data_ready = psock->save_data_ready;
1805         csk->sk_write_space = psock->save_write_space;
1806         csk->sk_state_change = psock->save_state_change;
1807         psock->rx_stopped = 1;
1808 
1809         if (WARN_ON(psock->rx_kcm)) {
1810                 write_unlock_bh(&csk->sk_callback_lock);
1811                 return;
1812         }
1813 
1814         spin_lock_bh(&mux->rx_lock);
1815 
1816         /* Stop receiver activities. After this point psock should not be
1817          * able to get onto ready list either through callbacks or work.
1818          */
1819         if (psock->ready_rx_msg) {
1820                 list_del(&psock->psock_ready_list);
1821                 kfree_skb(psock->ready_rx_msg);
1822                 psock->ready_rx_msg = NULL;
1823                 KCM_STATS_INCR(mux->stats.rx_ready_drops);
1824         }
1825 
1826         spin_unlock_bh(&mux->rx_lock);
1827 
1828         write_unlock_bh(&csk->sk_callback_lock);
1829 
1830         del_timer_sync(&psock->rx_msg_timer);
1831         cancel_work_sync(&psock->rx_work);
1832         cancel_delayed_work_sync(&psock->rx_delayed_work);
1833 
1834         bpf_prog_put(psock->bpf_prog);
1835 
1836         kfree_skb(psock->rx_skb_head);
1837         psock->rx_skb_head = NULL;
1838 
1839         spin_lock_bh(&mux->lock);
1840 
1841         aggregate_psock_stats(&psock->stats, &mux->aggregate_psock_stats);
1842 
1843         KCM_STATS_INCR(mux->stats.psock_unattach);
1844 
1845         if (psock->tx_kcm) {
1846                 /* psock was reserved.  Just mark it finished and we will clean
1847                  * up in the kcm paths, we need kcm lock which can not be
1848                  * acquired here.
1849                  */
1850                 KCM_STATS_INCR(mux->stats.psock_unattach_rsvd);
1851                 spin_unlock_bh(&mux->lock);
1852 
1853                 /* We are unattaching a socket that is reserved. Abort the
1854                  * socket since we may be out of sync in sending on it. We need
1855                  * to do this without the mux lock.
1856                  */
1857                 kcm_abort_tx_psock(psock, EPIPE, false);
1858 
1859                 spin_lock_bh(&mux->lock);
1860                 if (!psock->tx_kcm) {
1861                         /* psock now unreserved in window mux was unlocked */
1862                         goto no_reserved;
1863                 }
1864                 psock->done = 1;
1865 
1866                 /* Commit done before queuing work to process it */
1867                 smp_mb();
1868 
1869                 /* Queue tx work to make sure psock->done is handled */
1870                 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
1871                 spin_unlock_bh(&mux->lock);
1872         } else {
1873 no_reserved:
1874                 if (!psock->tx_stopped)
1875                         list_del(&psock->psock_avail_list);
1876                 list_del(&psock->psock_list);
1877                 mux->psocks_cnt--;
1878                 spin_unlock_bh(&mux->lock);
1879 
1880                 sock_put(csk);
1881                 fput(csk->sk_socket->file);
1882                 kmem_cache_free(kcm_psockp, psock);
1883         }
1884 }
1885 
1886 static int kcm_unattach_ioctl(struct socket *sock, struct kcm_unattach *info)
1887 {
1888         struct kcm_sock *kcm = kcm_sk(sock->sk);
1889         struct kcm_mux *mux = kcm->mux;
1890         struct kcm_psock *psock;
1891         struct socket *csock;
1892         struct sock *csk;
1893         int err;
1894 
1895         csock = sockfd_lookup(info->fd, &err);
1896         if (!csock)
1897                 return -ENOENT;
1898 
1899         csk = csock->sk;
1900         if (!csk) {
1901                 err = -EINVAL;
1902                 goto out;
1903         }
1904 
1905         err = -ENOENT;
1906 
1907         spin_lock_bh(&mux->lock);
1908 
1909         list_for_each_entry(psock, &mux->psocks, psock_list) {
1910                 if (psock->sk != csk)
1911                         continue;
1912 
1913                 /* Found the matching psock */
1914 
1915                 if (psock->unattaching || WARN_ON(psock->done)) {
1916                         err = -EALREADY;
1917                         break;
1918                 }
1919 
1920                 psock->unattaching = 1;
1921 
1922                 spin_unlock_bh(&mux->lock);
1923 
1924                 kcm_unattach(psock);
1925 
1926                 err = 0;
1927                 goto out;
1928         }
1929 
1930         spin_unlock_bh(&mux->lock);
1931 
1932 out:
1933         fput(csock->file);
1934         return err;
1935 }
1936 
1937 static struct proto kcm_proto = {
1938         .name   = "KCM",
1939         .owner  = THIS_MODULE,
1940         .obj_size = sizeof(struct kcm_sock),
1941 };
1942 
1943 /* Clone a kcm socket. */
1944 static int kcm_clone(struct socket *osock, struct kcm_clone *info,
1945                      struct socket **newsockp)
1946 {
1947         struct socket *newsock;
1948         struct sock *newsk;
1949         struct file *newfile;
1950         int err, newfd;
1951 
1952         err = -ENFILE;
1953         newsock = sock_alloc();
1954         if (!newsock)
1955                 goto out;
1956 
1957         newsock->type = osock->type;
1958         newsock->ops = osock->ops;
1959 
1960         __module_get(newsock->ops->owner);
1961 
1962         newfd = get_unused_fd_flags(0);
1963         if (unlikely(newfd < 0)) {
1964                 err = newfd;
1965                 goto out_fd_fail;
1966         }
1967 
1968         newfile = sock_alloc_file(newsock, 0, osock->sk->sk_prot_creator->name);
1969         if (unlikely(IS_ERR(newfile))) {
1970                 err = PTR_ERR(newfile);
1971                 goto out_sock_alloc_fail;
1972         }
1973 
1974         newsk = sk_alloc(sock_net(osock->sk), PF_KCM, GFP_KERNEL,
1975                          &kcm_proto, true);
1976         if (!newsk) {
1977                 err = -ENOMEM;
1978                 goto out_sk_alloc_fail;
1979         }
1980 
1981         sock_init_data(newsock, newsk);
1982         init_kcm_sock(kcm_sk(newsk), kcm_sk(osock->sk)->mux);
1983 
1984         fd_install(newfd, newfile);
1985         *newsockp = newsock;
1986         info->fd = newfd;
1987 
1988         return 0;
1989 
1990 out_sk_alloc_fail:
1991         fput(newfile);
1992 out_sock_alloc_fail:
1993         put_unused_fd(newfd);
1994 out_fd_fail:
1995         sock_release(newsock);
1996 out:
1997         return err;
1998 }
1999 
2000 static int kcm_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
2001 {
2002         int err;
2003 
2004         switch (cmd) {
2005         case SIOCKCMATTACH: {
2006                 struct kcm_attach info;
2007 
2008                 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
2009                         err = -EFAULT;
2010 
2011                 err = kcm_attach_ioctl(sock, &info);
2012 
2013                 break;
2014         }
2015         case SIOCKCMUNATTACH: {
2016                 struct kcm_unattach info;
2017 
2018                 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
2019                         err = -EFAULT;
2020 
2021                 err = kcm_unattach_ioctl(sock, &info);
2022 
2023                 break;
2024         }
2025         case SIOCKCMCLONE: {
2026                 struct kcm_clone info;
2027                 struct socket *newsock = NULL;
2028 
2029                 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
2030                         err = -EFAULT;
2031 
2032                 err = kcm_clone(sock, &info, &newsock);
2033 
2034                 if (!err) {
2035                         if (copy_to_user((void __user *)arg, &info,
2036                                          sizeof(info))) {
2037                                 err = -EFAULT;
2038                                 sock_release(newsock);
2039                         }
2040                 }
2041 
2042                 break;
2043         }
2044         default:
2045                 err = -ENOIOCTLCMD;
2046                 break;
2047         }
2048 
2049         return err;
2050 }
2051 
2052 static void free_mux(struct rcu_head *rcu)
2053 {
2054         struct kcm_mux *mux = container_of(rcu,
2055             struct kcm_mux, rcu);
2056 
2057         kmem_cache_free(kcm_muxp, mux);
2058 }
2059 
2060 static void release_mux(struct kcm_mux *mux)
2061 {
2062         struct kcm_net *knet = mux->knet;
2063         struct kcm_psock *psock, *tmp_psock;
2064 
2065         /* Release psocks */
2066         list_for_each_entry_safe(psock, tmp_psock,
2067                                  &mux->psocks, psock_list) {
2068                 if (!WARN_ON(psock->unattaching))
2069                         kcm_unattach(psock);
2070         }
2071 
2072         if (WARN_ON(mux->psocks_cnt))
2073                 return;
2074 
2075         __skb_queue_purge(&mux->rx_hold_queue);
2076 
2077         mutex_lock(&knet->mutex);
2078         aggregate_mux_stats(&mux->stats, &knet->aggregate_mux_stats);
2079         aggregate_psock_stats(&mux->aggregate_psock_stats,
2080                               &knet->aggregate_psock_stats);
2081         list_del_rcu(&mux->kcm_mux_list);
2082         knet->count--;
2083         mutex_unlock(&knet->mutex);
2084 
2085         call_rcu(&mux->rcu, free_mux);
2086 }
2087 
2088 static void kcm_done(struct kcm_sock *kcm)
2089 {
2090         struct kcm_mux *mux = kcm->mux;
2091         struct sock *sk = &kcm->sk;
2092         int socks_cnt;
2093 
2094         spin_lock_bh(&mux->rx_lock);
2095         if (kcm->rx_psock) {
2096                 /* Cleanup in unreserve_rx_kcm */
2097                 WARN_ON(kcm->done);
2098                 kcm->rx_disabled = 1;
2099                 kcm->done = 1;
2100                 spin_unlock_bh(&mux->rx_lock);
2101                 return;
2102         }
2103 
2104         if (kcm->rx_wait) {
2105                 list_del(&kcm->wait_rx_list);
2106                 kcm->rx_wait = false;
2107         }
2108         /* Move any pending receive messages to other kcm sockets */
2109         requeue_rx_msgs(mux, &sk->sk_receive_queue);
2110 
2111         spin_unlock_bh(&mux->rx_lock);
2112 
2113         if (WARN_ON(sk_rmem_alloc_get(sk)))
2114                 return;
2115 
2116         /* Detach from MUX */
2117         spin_lock_bh(&mux->lock);
2118 
2119         list_del(&kcm->kcm_sock_list);
2120         mux->kcm_socks_cnt--;
2121         socks_cnt = mux->kcm_socks_cnt;
2122 
2123         spin_unlock_bh(&mux->lock);
2124 
2125         if (!socks_cnt) {
2126                 /* We are done with the mux now. */
2127                 release_mux(mux);
2128         }
2129 
2130         WARN_ON(kcm->rx_wait);
2131 
2132         sock_put(&kcm->sk);
2133 }
2134 
2135 /* Called by kcm_release to close a KCM socket.
2136  * If this is the last KCM socket on the MUX, destroy the MUX.
2137  */
2138 static int kcm_release(struct socket *sock)
2139 {
2140         struct sock *sk = sock->sk;
2141         struct kcm_sock *kcm;
2142         struct kcm_mux *mux;
2143         struct kcm_psock *psock;
2144 
2145         if (!sk)
2146                 return 0;
2147 
2148         kcm = kcm_sk(sk);
2149         mux = kcm->mux;
2150 
2151         sock_orphan(sk);
2152         kfree_skb(kcm->seq_skb);
2153 
2154         lock_sock(sk);
2155         /* Purge queue under lock to avoid race condition with tx_work trying
2156          * to act when queue is nonempty. If tx_work runs after this point
2157          * it will just return.
2158          */
2159         __skb_queue_purge(&sk->sk_write_queue);
2160         release_sock(sk);
2161 
2162         spin_lock_bh(&mux->lock);
2163         if (kcm->tx_wait) {
2164                 /* Take of tx_wait list, after this point there should be no way
2165                  * that a psock will be assigned to this kcm.
2166                  */
2167                 list_del(&kcm->wait_psock_list);
2168                 kcm->tx_wait = false;
2169         }
2170         spin_unlock_bh(&mux->lock);
2171 
2172         /* Cancel work. After this point there should be no outside references
2173          * to the kcm socket.
2174          */
2175         cancel_work_sync(&kcm->tx_work);
2176 
2177         lock_sock(sk);
2178         psock = kcm->tx_psock;
2179         if (psock) {
2180                 /* A psock was reserved, so we need to kill it since it
2181                  * may already have some bytes queued from a message. We
2182                  * need to do this after removing kcm from tx_wait list.
2183                  */
2184                 kcm_abort_tx_psock(psock, EPIPE, false);
2185                 unreserve_psock(kcm);
2186         }
2187         release_sock(sk);
2188 
2189         WARN_ON(kcm->tx_wait);
2190         WARN_ON(kcm->tx_psock);
2191 
2192         sock->sk = NULL;
2193 
2194         kcm_done(kcm);
2195 
2196         return 0;
2197 }
2198 
2199 static const struct proto_ops kcm_dgram_ops = {
2200         .family =       PF_KCM,
2201         .owner =        THIS_MODULE,
2202         .release =      kcm_release,
2203         .bind =         sock_no_bind,
2204         .connect =      sock_no_connect,
2205         .socketpair =   sock_no_socketpair,
2206         .accept =       sock_no_accept,
2207         .getname =      sock_no_getname,
2208         .poll =         datagram_poll,
2209         .ioctl =        kcm_ioctl,
2210         .listen =       sock_no_listen,
2211         .shutdown =     sock_no_shutdown,
2212         .setsockopt =   kcm_setsockopt,
2213         .getsockopt =   kcm_getsockopt,
2214         .sendmsg =      kcm_sendmsg,
2215         .recvmsg =      kcm_recvmsg,
2216         .mmap =         sock_no_mmap,
2217         .sendpage =     kcm_sendpage,
2218 };
2219 
2220 static const struct proto_ops kcm_seqpacket_ops = {
2221         .family =       PF_KCM,
2222         .owner =        THIS_MODULE,
2223         .release =      kcm_release,
2224         .bind =         sock_no_bind,
2225         .connect =      sock_no_connect,
2226         .socketpair =   sock_no_socketpair,
2227         .accept =       sock_no_accept,
2228         .getname =      sock_no_getname,
2229         .poll =         datagram_poll,
2230         .ioctl =        kcm_ioctl,
2231         .listen =       sock_no_listen,
2232         .shutdown =     sock_no_shutdown,
2233         .setsockopt =   kcm_setsockopt,
2234         .getsockopt =   kcm_getsockopt,
2235         .sendmsg =      kcm_sendmsg,
2236         .recvmsg =      kcm_recvmsg,
2237         .mmap =         sock_no_mmap,
2238         .sendpage =     kcm_sendpage,
2239         .splice_read =  kcm_splice_read,
2240 };
2241 
2242 /* Create proto operation for kcm sockets */
2243 static int kcm_create(struct net *net, struct socket *sock,
2244                       int protocol, int kern)
2245 {
2246         struct kcm_net *knet = net_generic(net, kcm_net_id);
2247         struct sock *sk;
2248         struct kcm_mux *mux;
2249 
2250         switch (sock->type) {
2251         case SOCK_DGRAM:
2252                 sock->ops = &kcm_dgram_ops;
2253                 break;
2254         case SOCK_SEQPACKET:
2255                 sock->ops = &kcm_seqpacket_ops;
2256                 break;
2257         default:
2258                 return -ESOCKTNOSUPPORT;
2259         }
2260 
2261         if (protocol != KCMPROTO_CONNECTED)
2262                 return -EPROTONOSUPPORT;
2263 
2264         sk = sk_alloc(net, PF_KCM, GFP_KERNEL, &kcm_proto, kern);
2265         if (!sk)
2266                 return -ENOMEM;
2267 
2268         /* Allocate a kcm mux, shared between KCM sockets */
2269         mux = kmem_cache_zalloc(kcm_muxp, GFP_KERNEL);
2270         if (!mux) {
2271                 sk_free(sk);
2272                 return -ENOMEM;
2273         }
2274 
2275         spin_lock_init(&mux->lock);
2276         spin_lock_init(&mux->rx_lock);
2277         INIT_LIST_HEAD(&mux->kcm_socks);
2278         INIT_LIST_HEAD(&mux->kcm_rx_waiters);
2279         INIT_LIST_HEAD(&mux->kcm_tx_waiters);
2280 
2281         INIT_LIST_HEAD(&mux->psocks);
2282         INIT_LIST_HEAD(&mux->psocks_ready);
2283         INIT_LIST_HEAD(&mux->psocks_avail);
2284 
2285         mux->knet = knet;
2286 
2287         /* Add new MUX to list */
2288         mutex_lock(&knet->mutex);
2289         list_add_rcu(&mux->kcm_mux_list, &knet->mux_list);
2290         knet->count++;
2291         mutex_unlock(&knet->mutex);
2292 
2293         skb_queue_head_init(&mux->rx_hold_queue);
2294 
2295         /* Init KCM socket */
2296         sock_init_data(sock, sk);
2297         init_kcm_sock(kcm_sk(sk), mux);
2298 
2299         return 0;
2300 }
2301 
2302 static struct net_proto_family kcm_family_ops = {
2303         .family = PF_KCM,
2304         .create = kcm_create,
2305         .owner  = THIS_MODULE,
2306 };
2307 
2308 static __net_init int kcm_init_net(struct net *net)
2309 {
2310         struct kcm_net *knet = net_generic(net, kcm_net_id);
2311 
2312         INIT_LIST_HEAD_RCU(&knet->mux_list);
2313         mutex_init(&knet->mutex);
2314 
2315         return 0;
2316 }
2317 
2318 static __net_exit void kcm_exit_net(struct net *net)
2319 {
2320         struct kcm_net *knet = net_generic(net, kcm_net_id);
2321 
2322         /* All KCM sockets should be closed at this point, which should mean
2323          * that all multiplexors and psocks have been destroyed.
2324          */
2325         WARN_ON(!list_empty(&knet->mux_list));
2326 }
2327 
2328 static struct pernet_operations kcm_net_ops = {
2329         .init = kcm_init_net,
2330         .exit = kcm_exit_net,
2331         .id   = &kcm_net_id,
2332         .size = sizeof(struct kcm_net),
2333 };
2334 
2335 static int __init kcm_init(void)
2336 {
2337         int err = -ENOMEM;
2338 
2339         kcm_muxp = kmem_cache_create("kcm_mux_cache",
2340                                      sizeof(struct kcm_mux), 0,
2341                                      SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
2342         if (!kcm_muxp)
2343                 goto fail;
2344 
2345         kcm_psockp = kmem_cache_create("kcm_psock_cache",
2346                                        sizeof(struct kcm_psock), 0,
2347                                         SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
2348         if (!kcm_psockp)
2349                 goto fail;
2350 
2351         kcm_wq = create_singlethread_workqueue("kkcmd");
2352         if (!kcm_wq)
2353                 goto fail;
2354 
2355         err = proto_register(&kcm_proto, 1);
2356         if (err)
2357                 goto fail;
2358 
2359         err = sock_register(&kcm_family_ops);
2360         if (err)
2361                 goto sock_register_fail;
2362 
2363         err = register_pernet_device(&kcm_net_ops);
2364         if (err)
2365                 goto net_ops_fail;
2366 
2367         err = kcm_proc_init();
2368         if (err)
2369                 goto proc_init_fail;
2370 
2371         return 0;
2372 
2373 proc_init_fail:
2374         unregister_pernet_device(&kcm_net_ops);
2375 
2376 net_ops_fail:
2377         sock_unregister(PF_KCM);
2378 
2379 sock_register_fail:
2380         proto_unregister(&kcm_proto);
2381 
2382 fail:
2383         kmem_cache_destroy(kcm_muxp);
2384         kmem_cache_destroy(kcm_psockp);
2385 
2386         if (kcm_wq)
2387                 destroy_workqueue(kcm_wq);
2388 
2389         return err;
2390 }
2391 
2392 static void __exit kcm_exit(void)
2393 {
2394         kcm_proc_exit();
2395         unregister_pernet_device(&kcm_net_ops);
2396         sock_unregister(PF_KCM);
2397         proto_unregister(&kcm_proto);
2398         destroy_workqueue(kcm_wq);
2399 
2400         kmem_cache_destroy(kcm_muxp);
2401         kmem_cache_destroy(kcm_psockp);
2402 }
2403 
2404 module_init(kcm_init);
2405 module_exit(kcm_exit);
2406 
2407 MODULE_LICENSE("GPL");
2408 MODULE_ALIAS_NETPROTO(PF_KCM);
2409 
2410 

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