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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         int res;
382 
383         res = bpf_prog_run_pin_on_cpu(prog, skb);
384         return res;
385 }
386 
387 static int kcm_read_sock_done(struct strparser *strp, int err)
388 {
389         struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
390 
391         unreserve_rx_kcm(psock, true);
392 
393         return err;
394 }
395 
396 static void psock_state_change(struct sock *sk)
397 {
398         /* TCP only does a EPOLLIN for a half close. Do a EPOLLHUP here
399          * since application will normally not poll with EPOLLIN
400          * on the TCP sockets.
401          */
402 
403         report_csk_error(sk, EPIPE);
404 }
405 
406 static void psock_write_space(struct sock *sk)
407 {
408         struct kcm_psock *psock;
409         struct kcm_mux *mux;
410         struct kcm_sock *kcm;
411 
412         read_lock_bh(&sk->sk_callback_lock);
413 
414         psock = (struct kcm_psock *)sk->sk_user_data;
415         if (unlikely(!psock))
416                 goto out;
417         mux = psock->mux;
418 
419         spin_lock_bh(&mux->lock);
420 
421         /* Check if the socket is reserved so someone is waiting for sending. */
422         kcm = psock->tx_kcm;
423         if (kcm && !unlikely(kcm->tx_stopped))
424                 queue_work(kcm_wq, &kcm->tx_work);
425 
426         spin_unlock_bh(&mux->lock);
427 out:
428         read_unlock_bh(&sk->sk_callback_lock);
429 }
430 
431 static void unreserve_psock(struct kcm_sock *kcm);
432 
433 /* kcm sock is locked. */
434 static struct kcm_psock *reserve_psock(struct kcm_sock *kcm)
435 {
436         struct kcm_mux *mux = kcm->mux;
437         struct kcm_psock *psock;
438 
439         psock = kcm->tx_psock;
440 
441         smp_rmb(); /* Must read tx_psock before tx_wait */
442 
443         if (psock) {
444                 WARN_ON(kcm->tx_wait);
445                 if (unlikely(psock->tx_stopped))
446                         unreserve_psock(kcm);
447                 else
448                         return kcm->tx_psock;
449         }
450 
451         spin_lock_bh(&mux->lock);
452 
453         /* Check again under lock to see if psock was reserved for this
454          * psock via psock_unreserve.
455          */
456         psock = kcm->tx_psock;
457         if (unlikely(psock)) {
458                 WARN_ON(kcm->tx_wait);
459                 spin_unlock_bh(&mux->lock);
460                 return kcm->tx_psock;
461         }
462 
463         if (!list_empty(&mux->psocks_avail)) {
464                 psock = list_first_entry(&mux->psocks_avail,
465                                          struct kcm_psock,
466                                          psock_avail_list);
467                 list_del(&psock->psock_avail_list);
468                 if (kcm->tx_wait) {
469                         list_del(&kcm->wait_psock_list);
470                         kcm->tx_wait = false;
471                 }
472                 kcm->tx_psock = psock;
473                 psock->tx_kcm = kcm;
474                 KCM_STATS_INCR(psock->stats.reserved);
475         } else if (!kcm->tx_wait) {
476                 list_add_tail(&kcm->wait_psock_list,
477                               &mux->kcm_tx_waiters);
478                 kcm->tx_wait = true;
479         }
480 
481         spin_unlock_bh(&mux->lock);
482 
483         return psock;
484 }
485 
486 /* mux lock held */
487 static void psock_now_avail(struct kcm_psock *psock)
488 {
489         struct kcm_mux *mux = psock->mux;
490         struct kcm_sock *kcm;
491 
492         if (list_empty(&mux->kcm_tx_waiters)) {
493                 list_add_tail(&psock->psock_avail_list,
494                               &mux->psocks_avail);
495         } else {
496                 kcm = list_first_entry(&mux->kcm_tx_waiters,
497                                        struct kcm_sock,
498                                        wait_psock_list);
499                 list_del(&kcm->wait_psock_list);
500                 kcm->tx_wait = false;
501                 psock->tx_kcm = kcm;
502 
503                 /* Commit before changing tx_psock since that is read in
504                  * reserve_psock before queuing work.
505                  */
506                 smp_mb();
507 
508                 kcm->tx_psock = psock;
509                 KCM_STATS_INCR(psock->stats.reserved);
510                 queue_work(kcm_wq, &kcm->tx_work);
511         }
512 }
513 
514 /* kcm sock is locked. */
515 static void unreserve_psock(struct kcm_sock *kcm)
516 {
517         struct kcm_psock *psock;
518         struct kcm_mux *mux = kcm->mux;
519 
520         spin_lock_bh(&mux->lock);
521 
522         psock = kcm->tx_psock;
523 
524         if (WARN_ON(!psock)) {
525                 spin_unlock_bh(&mux->lock);
526                 return;
527         }
528 
529         smp_rmb(); /* Read tx_psock before tx_wait */
530 
531         kcm_update_tx_mux_stats(mux, psock);
532 
533         WARN_ON(kcm->tx_wait);
534 
535         kcm->tx_psock = NULL;
536         psock->tx_kcm = NULL;
537         KCM_STATS_INCR(psock->stats.unreserved);
538 
539         if (unlikely(psock->tx_stopped)) {
540                 if (psock->done) {
541                         /* Deferred free */
542                         list_del(&psock->psock_list);
543                         mux->psocks_cnt--;
544                         sock_put(psock->sk);
545                         fput(psock->sk->sk_socket->file);
546                         kmem_cache_free(kcm_psockp, psock);
547                 }
548 
549                 /* Don't put back on available list */
550 
551                 spin_unlock_bh(&mux->lock);
552 
553                 return;
554         }
555 
556         psock_now_avail(psock);
557 
558         spin_unlock_bh(&mux->lock);
559 }
560 
561 static void kcm_report_tx_retry(struct kcm_sock *kcm)
562 {
563         struct kcm_mux *mux = kcm->mux;
564 
565         spin_lock_bh(&mux->lock);
566         KCM_STATS_INCR(mux->stats.tx_retries);
567         spin_unlock_bh(&mux->lock);
568 }
569 
570 /* Write any messages ready on the kcm socket.  Called with kcm sock lock
571  * held.  Return bytes actually sent or error.
572  */
573 static int kcm_write_msgs(struct kcm_sock *kcm)
574 {
575         struct sock *sk = &kcm->sk;
576         struct kcm_psock *psock;
577         struct sk_buff *skb, *head;
578         struct kcm_tx_msg *txm;
579         unsigned short fragidx, frag_offset;
580         unsigned int sent, total_sent = 0;
581         int ret = 0;
582 
583         kcm->tx_wait_more = false;
584         psock = kcm->tx_psock;
585         if (unlikely(psock && psock->tx_stopped)) {
586                 /* A reserved psock was aborted asynchronously. Unreserve
587                  * it and we'll retry the message.
588                  */
589                 unreserve_psock(kcm);
590                 kcm_report_tx_retry(kcm);
591                 if (skb_queue_empty(&sk->sk_write_queue))
592                         return 0;
593 
594                 kcm_tx_msg(skb_peek(&sk->sk_write_queue))->sent = 0;
595 
596         } else if (skb_queue_empty(&sk->sk_write_queue)) {
597                 return 0;
598         }
599 
600         head = skb_peek(&sk->sk_write_queue);
601         txm = kcm_tx_msg(head);
602 
603         if (txm->sent) {
604                 /* Send of first skbuff in queue already in progress */
605                 if (WARN_ON(!psock)) {
606                         ret = -EINVAL;
607                         goto out;
608                 }
609                 sent = txm->sent;
610                 frag_offset = txm->frag_offset;
611                 fragidx = txm->fragidx;
612                 skb = txm->frag_skb;
613 
614                 goto do_frag;
615         }
616 
617 try_again:
618         psock = reserve_psock(kcm);
619         if (!psock)
620                 goto out;
621 
622         do {
623                 skb = head;
624                 txm = kcm_tx_msg(head);
625                 sent = 0;
626 
627 do_frag_list:
628                 if (WARN_ON(!skb_shinfo(skb)->nr_frags)) {
629                         ret = -EINVAL;
630                         goto out;
631                 }
632 
633                 for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags;
634                      fragidx++) {
635                         skb_frag_t *frag;
636 
637                         frag_offset = 0;
638 do_frag:
639                         frag = &skb_shinfo(skb)->frags[fragidx];
640                         if (WARN_ON(!skb_frag_size(frag))) {
641                                 ret = -EINVAL;
642                                 goto out;
643                         }
644 
645                         ret = kernel_sendpage(psock->sk->sk_socket,
646                                               skb_frag_page(frag),
647                                               skb_frag_off(frag) + frag_offset,
648                                               skb_frag_size(frag) - frag_offset,
649                                               MSG_DONTWAIT);
650                         if (ret <= 0) {
651                                 if (ret == -EAGAIN) {
652                                         /* Save state to try again when there's
653                                          * write space on the socket
654                                          */
655                                         txm->sent = sent;
656                                         txm->frag_offset = frag_offset;
657                                         txm->fragidx = fragidx;
658                                         txm->frag_skb = skb;
659 
660                                         ret = 0;
661                                         goto out;
662                                 }
663 
664                                 /* Hard failure in sending message, abort this
665                                  * psock since it has lost framing
666                                  * synchonization and retry sending the
667                                  * message from the beginning.
668                                  */
669                                 kcm_abort_tx_psock(psock, ret ? -ret : EPIPE,
670                                                    true);
671                                 unreserve_psock(kcm);
672 
673                                 txm->sent = 0;
674                                 kcm_report_tx_retry(kcm);
675                                 ret = 0;
676 
677                                 goto try_again;
678                         }
679 
680                         sent += ret;
681                         frag_offset += ret;
682                         KCM_STATS_ADD(psock->stats.tx_bytes, ret);
683                         if (frag_offset < skb_frag_size(frag)) {
684                                 /* Not finished with this frag */
685                                 goto do_frag;
686                         }
687                 }
688 
689                 if (skb == head) {
690                         if (skb_has_frag_list(skb)) {
691                                 skb = skb_shinfo(skb)->frag_list;
692                                 goto do_frag_list;
693                         }
694                 } else if (skb->next) {
695                         skb = skb->next;
696                         goto do_frag_list;
697                 }
698 
699                 /* Successfully sent the whole packet, account for it. */
700                 skb_dequeue(&sk->sk_write_queue);
701                 kfree_skb(head);
702                 sk->sk_wmem_queued -= sent;
703                 total_sent += sent;
704                 KCM_STATS_INCR(psock->stats.tx_msgs);
705         } while ((head = skb_peek(&sk->sk_write_queue)));
706 out:
707         if (!head) {
708                 /* Done with all queued messages. */
709                 WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
710                 unreserve_psock(kcm);
711         }
712 
713         /* Check if write space is available */
714         sk->sk_write_space(sk);
715 
716         return total_sent ? : ret;
717 }
718 
719 static void kcm_tx_work(struct work_struct *w)
720 {
721         struct kcm_sock *kcm = container_of(w, struct kcm_sock, tx_work);
722         struct sock *sk = &kcm->sk;
723         int err;
724 
725         lock_sock(sk);
726 
727         /* Primarily for SOCK_DGRAM sockets, also handle asynchronous tx
728          * aborts
729          */
730         err = kcm_write_msgs(kcm);
731         if (err < 0) {
732                 /* Hard failure in write, report error on KCM socket */
733                 pr_warn("KCM: Hard failure on kcm_write_msgs %d\n", err);
734                 report_csk_error(&kcm->sk, -err);
735                 goto out;
736         }
737 
738         /* Primarily for SOCK_SEQPACKET sockets */
739         if (likely(sk->sk_socket) &&
740             test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
741                 clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
742                 sk->sk_write_space(sk);
743         }
744 
745 out:
746         release_sock(sk);
747 }
748 
749 static void kcm_push(struct kcm_sock *kcm)
750 {
751         if (kcm->tx_wait_more)
752                 kcm_write_msgs(kcm);
753 }
754 
755 static ssize_t kcm_sendpage(struct socket *sock, struct page *page,
756                             int offset, size_t size, int flags)
757 
758 {
759         struct sock *sk = sock->sk;
760         struct kcm_sock *kcm = kcm_sk(sk);
761         struct sk_buff *skb = NULL, *head = NULL;
762         long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
763         bool eor;
764         int err = 0;
765         int i;
766 
767         if (flags & MSG_SENDPAGE_NOTLAST)
768                 flags |= MSG_MORE;
769 
770         /* No MSG_EOR from splice, only look at MSG_MORE */
771         eor = !(flags & MSG_MORE);
772 
773         lock_sock(sk);
774 
775         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
776 
777         err = -EPIPE;
778         if (sk->sk_err)
779                 goto out_error;
780 
781         if (kcm->seq_skb) {
782                 /* Previously opened message */
783                 head = kcm->seq_skb;
784                 skb = kcm_tx_msg(head)->last_skb;
785                 i = skb_shinfo(skb)->nr_frags;
786 
787                 if (skb_can_coalesce(skb, i, page, offset)) {
788                         skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
789                         skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
790                         goto coalesced;
791                 }
792 
793                 if (i >= MAX_SKB_FRAGS) {
794                         struct sk_buff *tskb;
795 
796                         tskb = alloc_skb(0, sk->sk_allocation);
797                         while (!tskb) {
798                                 kcm_push(kcm);
799                                 err = sk_stream_wait_memory(sk, &timeo);
800                                 if (err)
801                                         goto out_error;
802                         }
803 
804                         if (head == skb)
805                                 skb_shinfo(head)->frag_list = tskb;
806                         else
807                                 skb->next = tskb;
808 
809                         skb = tskb;
810                         skb->ip_summed = CHECKSUM_UNNECESSARY;
811                         i = 0;
812                 }
813         } else {
814                 /* Call the sk_stream functions to manage the sndbuf mem. */
815                 if (!sk_stream_memory_free(sk)) {
816                         kcm_push(kcm);
817                         set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
818                         err = sk_stream_wait_memory(sk, &timeo);
819                         if (err)
820                                 goto out_error;
821                 }
822 
823                 head = alloc_skb(0, sk->sk_allocation);
824                 while (!head) {
825                         kcm_push(kcm);
826                         err = sk_stream_wait_memory(sk, &timeo);
827                         if (err)
828                                 goto out_error;
829                 }
830 
831                 skb = head;
832                 i = 0;
833         }
834 
835         get_page(page);
836         skb_fill_page_desc(skb, i, page, offset, size);
837         skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
838 
839 coalesced:
840         skb->len += size;
841         skb->data_len += size;
842         skb->truesize += size;
843         sk->sk_wmem_queued += size;
844         sk_mem_charge(sk, size);
845 
846         if (head != skb) {
847                 head->len += size;
848                 head->data_len += size;
849                 head->truesize += size;
850         }
851 
852         if (eor) {
853                 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
854 
855                 /* Message complete, queue it on send buffer */
856                 __skb_queue_tail(&sk->sk_write_queue, head);
857                 kcm->seq_skb = NULL;
858                 KCM_STATS_INCR(kcm->stats.tx_msgs);
859 
860                 if (flags & MSG_BATCH) {
861                         kcm->tx_wait_more = true;
862                 } else if (kcm->tx_wait_more || not_busy) {
863                         err = kcm_write_msgs(kcm);
864                         if (err < 0) {
865                                 /* We got a hard error in write_msgs but have
866                                  * already queued this message. Report an error
867                                  * in the socket, but don't affect return value
868                                  * from sendmsg
869                                  */
870                                 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
871                                 report_csk_error(&kcm->sk, -err);
872                         }
873                 }
874         } else {
875                 /* Message not complete, save state */
876                 kcm->seq_skb = head;
877                 kcm_tx_msg(head)->last_skb = skb;
878         }
879 
880         KCM_STATS_ADD(kcm->stats.tx_bytes, size);
881 
882         release_sock(sk);
883         return size;
884 
885 out_error:
886         kcm_push(kcm);
887 
888         err = sk_stream_error(sk, flags, err);
889 
890         /* make sure we wake any epoll edge trigger waiter */
891         if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
892                 sk->sk_write_space(sk);
893 
894         release_sock(sk);
895         return err;
896 }
897 
898 static int kcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
899 {
900         struct sock *sk = sock->sk;
901         struct kcm_sock *kcm = kcm_sk(sk);
902         struct sk_buff *skb = NULL, *head = NULL;
903         size_t copy, copied = 0;
904         long timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
905         int eor = (sock->type == SOCK_DGRAM) ?
906                   !(msg->msg_flags & MSG_MORE) : !!(msg->msg_flags & MSG_EOR);
907         int err = -EPIPE;
908 
909         lock_sock(sk);
910 
911         /* Per tcp_sendmsg this should be in poll */
912         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
913 
914         if (sk->sk_err)
915                 goto out_error;
916 
917         if (kcm->seq_skb) {
918                 /* Previously opened message */
919                 head = kcm->seq_skb;
920                 skb = kcm_tx_msg(head)->last_skb;
921                 goto start;
922         }
923 
924         /* Call the sk_stream functions to manage the sndbuf mem. */
925         if (!sk_stream_memory_free(sk)) {
926                 kcm_push(kcm);
927                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
928                 err = sk_stream_wait_memory(sk, &timeo);
929                 if (err)
930                         goto out_error;
931         }
932 
933         if (msg_data_left(msg)) {
934                 /* New message, alloc head skb */
935                 head = alloc_skb(0, sk->sk_allocation);
936                 while (!head) {
937                         kcm_push(kcm);
938                         err = sk_stream_wait_memory(sk, &timeo);
939                         if (err)
940                                 goto out_error;
941 
942                         head = alloc_skb(0, sk->sk_allocation);
943                 }
944 
945                 skb = head;
946 
947                 /* Set ip_summed to CHECKSUM_UNNECESSARY to avoid calling
948                  * csum_and_copy_from_iter from skb_do_copy_data_nocache.
949                  */
950                 skb->ip_summed = CHECKSUM_UNNECESSARY;
951         }
952 
953 start:
954         while (msg_data_left(msg)) {
955                 bool merge = true;
956                 int i = skb_shinfo(skb)->nr_frags;
957                 struct page_frag *pfrag = sk_page_frag(sk);
958 
959                 if (!sk_page_frag_refill(sk, pfrag))
960                         goto wait_for_memory;
961 
962                 if (!skb_can_coalesce(skb, i, pfrag->page,
963                                       pfrag->offset)) {
964                         if (i == MAX_SKB_FRAGS) {
965                                 struct sk_buff *tskb;
966 
967                                 tskb = alloc_skb(0, sk->sk_allocation);
968                                 if (!tskb)
969                                         goto wait_for_memory;
970 
971                                 if (head == skb)
972                                         skb_shinfo(head)->frag_list = tskb;
973                                 else
974                                         skb->next = tskb;
975 
976                                 skb = tskb;
977                                 skb->ip_summed = CHECKSUM_UNNECESSARY;
978                                 continue;
979                         }
980                         merge = false;
981                 }
982 
983                 copy = min_t(int, msg_data_left(msg),
984                              pfrag->size - pfrag->offset);
985 
986                 if (!sk_wmem_schedule(sk, copy))
987                         goto wait_for_memory;
988 
989                 err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
990                                                pfrag->page,
991                                                pfrag->offset,
992                                                copy);
993                 if (err)
994                         goto out_error;
995 
996                 /* Update the skb. */
997                 if (merge) {
998                         skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
999                 } else {
1000                         skb_fill_page_desc(skb, i, pfrag->page,
1001                                            pfrag->offset, copy);
1002                         get_page(pfrag->page);
1003                 }
1004 
1005                 pfrag->offset += copy;
1006                 copied += copy;
1007                 if (head != skb) {
1008                         head->len += copy;
1009                         head->data_len += copy;
1010                 }
1011 
1012                 continue;
1013 
1014 wait_for_memory:
1015                 kcm_push(kcm);
1016                 err = sk_stream_wait_memory(sk, &timeo);
1017                 if (err)
1018                         goto out_error;
1019         }
1020 
1021         if (eor) {
1022                 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
1023 
1024                 if (head) {
1025                         /* Message complete, queue it on send buffer */
1026                         __skb_queue_tail(&sk->sk_write_queue, head);
1027                         kcm->seq_skb = NULL;
1028                         KCM_STATS_INCR(kcm->stats.tx_msgs);
1029                 }
1030 
1031                 if (msg->msg_flags & MSG_BATCH) {
1032                         kcm->tx_wait_more = true;
1033                 } else if (kcm->tx_wait_more || not_busy) {
1034                         err = kcm_write_msgs(kcm);
1035                         if (err < 0) {
1036                                 /* We got a hard error in write_msgs but have
1037                                  * already queued this message. Report an error
1038                                  * in the socket, but don't affect return value
1039                                  * from sendmsg
1040                                  */
1041                                 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
1042                                 report_csk_error(&kcm->sk, -err);
1043                         }
1044                 }
1045         } else {
1046                 /* Message not complete, save state */
1047 partial_message:
1048                 if (head) {
1049                         kcm->seq_skb = head;
1050                         kcm_tx_msg(head)->last_skb = skb;
1051                 }
1052         }
1053 
1054         KCM_STATS_ADD(kcm->stats.tx_bytes, copied);
1055 
1056         release_sock(sk);
1057         return copied;
1058 
1059 out_error:
1060         kcm_push(kcm);
1061 
1062         if (copied && sock->type == SOCK_SEQPACKET) {
1063                 /* Wrote some bytes before encountering an
1064                  * error, return partial success.
1065                  */
1066                 goto partial_message;
1067         }
1068 
1069         if (head != kcm->seq_skb)
1070                 kfree_skb(head);
1071 
1072         err = sk_stream_error(sk, msg->msg_flags, err);
1073 
1074         /* make sure we wake any epoll edge trigger waiter */
1075         if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
1076                 sk->sk_write_space(sk);
1077 
1078         release_sock(sk);
1079         return err;
1080 }
1081 
1082 static struct sk_buff *kcm_wait_data(struct sock *sk, int flags,
1083                                      long timeo, int *err)
1084 {
1085         struct sk_buff *skb;
1086 
1087         while (!(skb = skb_peek(&sk->sk_receive_queue))) {
1088                 if (sk->sk_err) {
1089                         *err = sock_error(sk);
1090                         return NULL;
1091                 }
1092 
1093                 if (sock_flag(sk, SOCK_DONE))
1094                         return NULL;
1095 
1096                 if ((flags & MSG_DONTWAIT) || !timeo) {
1097                         *err = -EAGAIN;
1098                         return NULL;
1099                 }
1100 
1101                 sk_wait_data(sk, &timeo, NULL);
1102 
1103                 /* Handle signals */
1104                 if (signal_pending(current)) {
1105                         *err = sock_intr_errno(timeo);
1106                         return NULL;
1107                 }
1108         }
1109 
1110         return skb;
1111 }
1112 
1113 static int kcm_recvmsg(struct socket *sock, struct msghdr *msg,
1114                        size_t len, int flags)
1115 {
1116         struct sock *sk = sock->sk;
1117         struct kcm_sock *kcm = kcm_sk(sk);
1118         int err = 0;
1119         long timeo;
1120         struct strp_msg *stm;
1121         int copied = 0;
1122         struct sk_buff *skb;
1123 
1124         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
1125 
1126         lock_sock(sk);
1127 
1128         skb = kcm_wait_data(sk, flags, timeo, &err);
1129         if (!skb)
1130                 goto out;
1131 
1132         /* Okay, have a message on the receive queue */
1133 
1134         stm = strp_msg(skb);
1135 
1136         if (len > stm->full_len)
1137                 len = stm->full_len;
1138 
1139         err = skb_copy_datagram_msg(skb, stm->offset, msg, len);
1140         if (err < 0)
1141                 goto out;
1142 
1143         copied = len;
1144         if (likely(!(flags & MSG_PEEK))) {
1145                 KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1146                 if (copied < stm->full_len) {
1147                         if (sock->type == SOCK_DGRAM) {
1148                                 /* Truncated message */
1149                                 msg->msg_flags |= MSG_TRUNC;
1150                                 goto msg_finished;
1151                         }
1152                         stm->offset += copied;
1153                         stm->full_len -= copied;
1154                 } else {
1155 msg_finished:
1156                         /* Finished with message */
1157                         msg->msg_flags |= MSG_EOR;
1158                         KCM_STATS_INCR(kcm->stats.rx_msgs);
1159                         skb_unlink(skb, &sk->sk_receive_queue);
1160                         kfree_skb(skb);
1161                 }
1162         }
1163 
1164 out:
1165         release_sock(sk);
1166 
1167         return copied ? : err;
1168 }
1169 
1170 static ssize_t kcm_splice_read(struct socket *sock, loff_t *ppos,
1171                                struct pipe_inode_info *pipe, size_t len,
1172                                unsigned int flags)
1173 {
1174         struct sock *sk = sock->sk;
1175         struct kcm_sock *kcm = kcm_sk(sk);
1176         long timeo;
1177         struct strp_msg *stm;
1178         int err = 0;
1179         ssize_t copied;
1180         struct sk_buff *skb;
1181 
1182         /* Only support splice for SOCKSEQPACKET */
1183 
1184         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
1185 
1186         lock_sock(sk);
1187 
1188         skb = kcm_wait_data(sk, flags, timeo, &err);
1189         if (!skb)
1190                 goto err_out;
1191 
1192         /* Okay, have a message on the receive queue */
1193 
1194         stm = strp_msg(skb);
1195 
1196         if (len > stm->full_len)
1197                 len = stm->full_len;
1198 
1199         copied = skb_splice_bits(skb, sk, stm->offset, pipe, len, flags);
1200         if (copied < 0) {
1201                 err = copied;
1202                 goto err_out;
1203         }
1204 
1205         KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1206 
1207         stm->offset += copied;
1208         stm->full_len -= copied;
1209 
1210         /* We have no way to return MSG_EOR. If all the bytes have been
1211          * read we still leave the message in the receive socket buffer.
1212          * A subsequent recvmsg needs to be done to return MSG_EOR and
1213          * finish reading the message.
1214          */
1215 
1216         release_sock(sk);
1217 
1218         return copied;
1219 
1220 err_out:
1221         release_sock(sk);
1222 
1223         return err;
1224 }
1225 
1226 /* kcm sock lock held */
1227 static void kcm_recv_disable(struct kcm_sock *kcm)
1228 {
1229         struct kcm_mux *mux = kcm->mux;
1230 
1231         if (kcm->rx_disabled)
1232                 return;
1233 
1234         spin_lock_bh(&mux->rx_lock);
1235 
1236         kcm->rx_disabled = 1;
1237 
1238         /* If a psock is reserved we'll do cleanup in unreserve */
1239         if (!kcm->rx_psock) {
1240                 if (kcm->rx_wait) {
1241                         list_del(&kcm->wait_rx_list);
1242                         kcm->rx_wait = false;
1243                 }
1244 
1245                 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
1246         }
1247 
1248         spin_unlock_bh(&mux->rx_lock);
1249 }
1250 
1251 /* kcm sock lock held */
1252 static void kcm_recv_enable(struct kcm_sock *kcm)
1253 {
1254         struct kcm_mux *mux = kcm->mux;
1255 
1256         if (!kcm->rx_disabled)
1257                 return;
1258 
1259         spin_lock_bh(&mux->rx_lock);
1260 
1261         kcm->rx_disabled = 0;
1262         kcm_rcv_ready(kcm);
1263 
1264         spin_unlock_bh(&mux->rx_lock);
1265 }
1266 
1267 static int kcm_setsockopt(struct socket *sock, int level, int optname,
1268                           sockptr_t optval, unsigned int optlen)
1269 {
1270         struct kcm_sock *kcm = kcm_sk(sock->sk);
1271         int val, valbool;
1272         int err = 0;
1273 
1274         if (level != SOL_KCM)
1275                 return -ENOPROTOOPT;
1276 
1277         if (optlen < sizeof(int))
1278                 return -EINVAL;
1279 
1280         if (copy_from_sockptr(&val, optval, sizeof(int)))
1281                 return -EFAULT;
1282 
1283         valbool = val ? 1 : 0;
1284 
1285         switch (optname) {
1286         case KCM_RECV_DISABLE:
1287                 lock_sock(&kcm->sk);
1288                 if (valbool)
1289                         kcm_recv_disable(kcm);
1290                 else
1291                         kcm_recv_enable(kcm);
1292                 release_sock(&kcm->sk);
1293                 break;
1294         default:
1295                 err = -ENOPROTOOPT;
1296         }
1297 
1298         return err;
1299 }
1300 
1301 static int kcm_getsockopt(struct socket *sock, int level, int optname,
1302                           char __user *optval, int __user *optlen)
1303 {
1304         struct kcm_sock *kcm = kcm_sk(sock->sk);
1305         int val, len;
1306 
1307         if (level != SOL_KCM)
1308                 return -ENOPROTOOPT;
1309 
1310         if (get_user(len, optlen))
1311                 return -EFAULT;
1312 
1313         len = min_t(unsigned int, len, sizeof(int));
1314         if (len < 0)
1315                 return -EINVAL;
1316 
1317         switch (optname) {
1318         case KCM_RECV_DISABLE:
1319                 val = kcm->rx_disabled;
1320                 break;
1321         default:
1322                 return -ENOPROTOOPT;
1323         }
1324 
1325         if (put_user(len, optlen))
1326                 return -EFAULT;
1327         if (copy_to_user(optval, &val, len))
1328                 return -EFAULT;
1329         return 0;
1330 }
1331 
1332 static void init_kcm_sock(struct kcm_sock *kcm, struct kcm_mux *mux)
1333 {
1334         struct kcm_sock *tkcm;
1335         struct list_head *head;
1336         int index = 0;
1337 
1338         /* For SOCK_SEQPACKET sock type, datagram_poll checks the sk_state, so
1339          * we set sk_state, otherwise epoll_wait always returns right away with
1340          * EPOLLHUP
1341          */
1342         kcm->sk.sk_state = TCP_ESTABLISHED;
1343 
1344         /* Add to mux's kcm sockets list */
1345         kcm->mux = mux;
1346         spin_lock_bh(&mux->lock);
1347 
1348         head = &mux->kcm_socks;
1349         list_for_each_entry(tkcm, &mux->kcm_socks, kcm_sock_list) {
1350                 if (tkcm->index != index)
1351                         break;
1352                 head = &tkcm->kcm_sock_list;
1353                 index++;
1354         }
1355 
1356         list_add(&kcm->kcm_sock_list, head);
1357         kcm->index = index;
1358 
1359         mux->kcm_socks_cnt++;
1360         spin_unlock_bh(&mux->lock);
1361 
1362         INIT_WORK(&kcm->tx_work, kcm_tx_work);
1363 
1364         spin_lock_bh(&mux->rx_lock);
1365         kcm_rcv_ready(kcm);
1366         spin_unlock_bh(&mux->rx_lock);
1367 }
1368 
1369 static int kcm_attach(struct socket *sock, struct socket *csock,
1370                       struct bpf_prog *prog)
1371 {
1372         struct kcm_sock *kcm = kcm_sk(sock->sk);
1373         struct kcm_mux *mux = kcm->mux;
1374         struct sock *csk;
1375         struct kcm_psock *psock = NULL, *tpsock;
1376         struct list_head *head;
1377         int index = 0;
1378         static const struct strp_callbacks cb = {
1379                 .rcv_msg = kcm_rcv_strparser,
1380                 .parse_msg = kcm_parse_func_strparser,
1381                 .read_sock_done = kcm_read_sock_done,
1382         };
1383         int err = 0;
1384 
1385         csk = csock->sk;
1386         if (!csk)
1387                 return -EINVAL;
1388 
1389         lock_sock(csk);
1390 
1391         /* Only allow TCP sockets to be attached for now */
1392         if ((csk->sk_family != AF_INET && csk->sk_family != AF_INET6) ||
1393             csk->sk_protocol != IPPROTO_TCP) {
1394                 err = -EOPNOTSUPP;
1395                 goto out;
1396         }
1397 
1398         /* Don't allow listeners or closed sockets */
1399         if (csk->sk_state == TCP_LISTEN || csk->sk_state == TCP_CLOSE) {
1400                 err = -EOPNOTSUPP;
1401                 goto out;
1402         }
1403 
1404         psock = kmem_cache_zalloc(kcm_psockp, GFP_KERNEL);
1405         if (!psock) {
1406                 err = -ENOMEM;
1407                 goto out;
1408         }
1409 
1410         psock->mux = mux;
1411         psock->sk = csk;
1412         psock->bpf_prog = prog;
1413 
1414         err = strp_init(&psock->strp, csk, &cb);
1415         if (err) {
1416                 kmem_cache_free(kcm_psockp, psock);
1417                 goto out;
1418         }
1419 
1420         write_lock_bh(&csk->sk_callback_lock);
1421 
1422         /* Check if sk_user_data is aready by KCM or someone else.
1423          * Must be done under lock to prevent race conditions.
1424          */
1425         if (csk->sk_user_data) {
1426                 write_unlock_bh(&csk->sk_callback_lock);
1427                 strp_stop(&psock->strp);
1428                 strp_done(&psock->strp);
1429                 kmem_cache_free(kcm_psockp, psock);
1430                 err = -EALREADY;
1431                 goto out;
1432         }
1433 
1434         psock->save_data_ready = csk->sk_data_ready;
1435         psock->save_write_space = csk->sk_write_space;
1436         psock->save_state_change = csk->sk_state_change;
1437         csk->sk_user_data = psock;
1438         csk->sk_data_ready = psock_data_ready;
1439         csk->sk_write_space = psock_write_space;
1440         csk->sk_state_change = psock_state_change;
1441 
1442         write_unlock_bh(&csk->sk_callback_lock);
1443 
1444         sock_hold(csk);
1445 
1446         /* Finished initialization, now add the psock to the MUX. */
1447         spin_lock_bh(&mux->lock);
1448         head = &mux->psocks;
1449         list_for_each_entry(tpsock, &mux->psocks, psock_list) {
1450                 if (tpsock->index != index)
1451                         break;
1452                 head = &tpsock->psock_list;
1453                 index++;
1454         }
1455 
1456         list_add(&psock->psock_list, head);
1457         psock->index = index;
1458 
1459         KCM_STATS_INCR(mux->stats.psock_attach);
1460         mux->psocks_cnt++;
1461         psock_now_avail(psock);
1462         spin_unlock_bh(&mux->lock);
1463 
1464         /* Schedule RX work in case there are already bytes queued */
1465         strp_check_rcv(&psock->strp);
1466 
1467 out:
1468         release_sock(csk);
1469 
1470         return err;
1471 }
1472 
1473 static int kcm_attach_ioctl(struct socket *sock, struct kcm_attach *info)
1474 {
1475         struct socket *csock;
1476         struct bpf_prog *prog;
1477         int err;
1478 
1479         csock = sockfd_lookup(info->fd, &err);
1480         if (!csock)
1481                 return -ENOENT;
1482 
1483         prog = bpf_prog_get_type(info->bpf_fd, BPF_PROG_TYPE_SOCKET_FILTER);
1484         if (IS_ERR(prog)) {
1485                 err = PTR_ERR(prog);
1486                 goto out;
1487         }
1488 
1489         err = kcm_attach(sock, csock, prog);
1490         if (err) {
1491                 bpf_prog_put(prog);
1492                 goto out;
1493         }
1494 
1495         /* Keep reference on file also */
1496 
1497         return 0;
1498 out:
1499         fput(csock->file);
1500         return err;
1501 }
1502 
1503 static void kcm_unattach(struct kcm_psock *psock)
1504 {
1505         struct sock *csk = psock->sk;
1506         struct kcm_mux *mux = psock->mux;
1507 
1508         lock_sock(csk);
1509 
1510         /* Stop getting callbacks from TCP socket. After this there should
1511          * be no way to reserve a kcm for this psock.
1512          */
1513         write_lock_bh(&csk->sk_callback_lock);
1514         csk->sk_user_data = NULL;
1515         csk->sk_data_ready = psock->save_data_ready;
1516         csk->sk_write_space = psock->save_write_space;
1517         csk->sk_state_change = psock->save_state_change;
1518         strp_stop(&psock->strp);
1519 
1520         if (WARN_ON(psock->rx_kcm)) {
1521                 write_unlock_bh(&csk->sk_callback_lock);
1522                 release_sock(csk);
1523                 return;
1524         }
1525 
1526         spin_lock_bh(&mux->rx_lock);
1527 
1528         /* Stop receiver activities. After this point psock should not be
1529          * able to get onto ready list either through callbacks or work.
1530          */
1531         if (psock->ready_rx_msg) {
1532                 list_del(&psock->psock_ready_list);
1533                 kfree_skb(psock->ready_rx_msg);
1534                 psock->ready_rx_msg = NULL;
1535                 KCM_STATS_INCR(mux->stats.rx_ready_drops);
1536         }
1537 
1538         spin_unlock_bh(&mux->rx_lock);
1539 
1540         write_unlock_bh(&csk->sk_callback_lock);
1541 
1542         /* Call strp_done without sock lock */
1543         release_sock(csk);
1544         strp_done(&psock->strp);
1545         lock_sock(csk);
1546 
1547         bpf_prog_put(psock->bpf_prog);
1548 
1549         spin_lock_bh(&mux->lock);
1550 
1551         aggregate_psock_stats(&psock->stats, &mux->aggregate_psock_stats);
1552         save_strp_stats(&psock->strp, &mux->aggregate_strp_stats);
1553 
1554         KCM_STATS_INCR(mux->stats.psock_unattach);
1555 
1556         if (psock->tx_kcm) {
1557                 /* psock was reserved.  Just mark it finished and we will clean
1558                  * up in the kcm paths, we need kcm lock which can not be
1559                  * acquired here.
1560                  */
1561                 KCM_STATS_INCR(mux->stats.psock_unattach_rsvd);
1562                 spin_unlock_bh(&mux->lock);
1563 
1564                 /* We are unattaching a socket that is reserved. Abort the
1565                  * socket since we may be out of sync in sending on it. We need
1566                  * to do this without the mux lock.
1567                  */
1568                 kcm_abort_tx_psock(psock, EPIPE, false);
1569 
1570                 spin_lock_bh(&mux->lock);
1571                 if (!psock->tx_kcm) {
1572                         /* psock now unreserved in window mux was unlocked */
1573                         goto no_reserved;
1574                 }
1575                 psock->done = 1;
1576 
1577                 /* Commit done before queuing work to process it */
1578                 smp_mb();
1579 
1580                 /* Queue tx work to make sure psock->done is handled */
1581                 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
1582                 spin_unlock_bh(&mux->lock);
1583         } else {
1584 no_reserved:
1585                 if (!psock->tx_stopped)
1586                         list_del(&psock->psock_avail_list);
1587                 list_del(&psock->psock_list);
1588                 mux->psocks_cnt--;
1589                 spin_unlock_bh(&mux->lock);
1590 
1591                 sock_put(csk);
1592                 fput(csk->sk_socket->file);
1593                 kmem_cache_free(kcm_psockp, psock);
1594         }
1595 
1596         release_sock(csk);
1597 }
1598 
1599 static int kcm_unattach_ioctl(struct socket *sock, struct kcm_unattach *info)
1600 {
1601         struct kcm_sock *kcm = kcm_sk(sock->sk);
1602         struct kcm_mux *mux = kcm->mux;
1603         struct kcm_psock *psock;
1604         struct socket *csock;
1605         struct sock *csk;
1606         int err;
1607 
1608         csock = sockfd_lookup(info->fd, &err);
1609         if (!csock)
1610                 return -ENOENT;
1611 
1612         csk = csock->sk;
1613         if (!csk) {
1614                 err = -EINVAL;
1615                 goto out;
1616         }
1617 
1618         err = -ENOENT;
1619 
1620         spin_lock_bh(&mux->lock);
1621 
1622         list_for_each_entry(psock, &mux->psocks, psock_list) {
1623                 if (psock->sk != csk)
1624                         continue;
1625 
1626                 /* Found the matching psock */
1627 
1628                 if (psock->unattaching || WARN_ON(psock->done)) {
1629                         err = -EALREADY;
1630                         break;
1631                 }
1632 
1633                 psock->unattaching = 1;
1634 
1635                 spin_unlock_bh(&mux->lock);
1636 
1637                 /* Lower socket lock should already be held */
1638                 kcm_unattach(psock);
1639 
1640                 err = 0;
1641                 goto out;
1642         }
1643 
1644         spin_unlock_bh(&mux->lock);
1645 
1646 out:
1647         fput(csock->file);
1648         return err;
1649 }
1650 
1651 static struct proto kcm_proto = {
1652         .name   = "KCM",
1653         .owner  = THIS_MODULE,
1654         .obj_size = sizeof(struct kcm_sock),
1655 };
1656 
1657 /* Clone a kcm socket. */
1658 static struct file *kcm_clone(struct socket *osock)
1659 {
1660         struct socket *newsock;
1661         struct sock *newsk;
1662 
1663         newsock = sock_alloc();
1664         if (!newsock)
1665                 return ERR_PTR(-ENFILE);
1666 
1667         newsock->type = osock->type;
1668         newsock->ops = osock->ops;
1669 
1670         __module_get(newsock->ops->owner);
1671 
1672         newsk = sk_alloc(sock_net(osock->sk), PF_KCM, GFP_KERNEL,
1673                          &kcm_proto, false);
1674         if (!newsk) {
1675                 sock_release(newsock);
1676                 return ERR_PTR(-ENOMEM);
1677         }
1678         sock_init_data(newsock, newsk);
1679         init_kcm_sock(kcm_sk(newsk), kcm_sk(osock->sk)->mux);
1680 
1681         return sock_alloc_file(newsock, 0, osock->sk->sk_prot_creator->name);
1682 }
1683 
1684 static int kcm_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
1685 {
1686         int err;
1687 
1688         switch (cmd) {
1689         case SIOCKCMATTACH: {
1690                 struct kcm_attach info;
1691 
1692                 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1693                         return -EFAULT;
1694 
1695                 err = kcm_attach_ioctl(sock, &info);
1696 
1697                 break;
1698         }
1699         case SIOCKCMUNATTACH: {
1700                 struct kcm_unattach info;
1701 
1702                 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1703                         return -EFAULT;
1704 
1705                 err = kcm_unattach_ioctl(sock, &info);
1706 
1707                 break;
1708         }
1709         case SIOCKCMCLONE: {
1710                 struct kcm_clone info;
1711                 struct file *file;
1712 
1713                 info.fd = get_unused_fd_flags(0);
1714                 if (unlikely(info.fd < 0))
1715                         return info.fd;
1716 
1717                 file = kcm_clone(sock);
1718                 if (IS_ERR(file)) {
1719                         put_unused_fd(info.fd);
1720                         return PTR_ERR(file);
1721                 }
1722                 if (copy_to_user((void __user *)arg, &info,
1723                                  sizeof(info))) {
1724                         put_unused_fd(info.fd);
1725                         fput(file);
1726                         return -EFAULT;
1727                 }
1728                 fd_install(info.fd, file);
1729                 err = 0;
1730                 break;
1731         }
1732         default:
1733                 err = -ENOIOCTLCMD;
1734                 break;
1735         }
1736 
1737         return err;
1738 }
1739 
1740 static void free_mux(struct rcu_head *rcu)
1741 {
1742         struct kcm_mux *mux = container_of(rcu,
1743             struct kcm_mux, rcu);
1744 
1745         kmem_cache_free(kcm_muxp, mux);
1746 }
1747 
1748 static void release_mux(struct kcm_mux *mux)
1749 {
1750         struct kcm_net *knet = mux->knet;
1751         struct kcm_psock *psock, *tmp_psock;
1752 
1753         /* Release psocks */
1754         list_for_each_entry_safe(psock, tmp_psock,
1755                                  &mux->psocks, psock_list) {
1756                 if (!WARN_ON(psock->unattaching))
1757                         kcm_unattach(psock);
1758         }
1759 
1760         if (WARN_ON(mux->psocks_cnt))
1761                 return;
1762 
1763         __skb_queue_purge(&mux->rx_hold_queue);
1764 
1765         mutex_lock(&knet->mutex);
1766         aggregate_mux_stats(&mux->stats, &knet->aggregate_mux_stats);
1767         aggregate_psock_stats(&mux->aggregate_psock_stats,
1768                               &knet->aggregate_psock_stats);
1769         aggregate_strp_stats(&mux->aggregate_strp_stats,
1770                              &knet->aggregate_strp_stats);
1771         list_del_rcu(&mux->kcm_mux_list);
1772         knet->count--;
1773         mutex_unlock(&knet->mutex);
1774 
1775         call_rcu(&mux->rcu, free_mux);
1776 }
1777 
1778 static void kcm_done(struct kcm_sock *kcm)
1779 {
1780         struct kcm_mux *mux = kcm->mux;
1781         struct sock *sk = &kcm->sk;
1782         int socks_cnt;
1783 
1784         spin_lock_bh(&mux->rx_lock);
1785         if (kcm->rx_psock) {
1786                 /* Cleanup in unreserve_rx_kcm */
1787                 WARN_ON(kcm->done);
1788                 kcm->rx_disabled = 1;
1789                 kcm->done = 1;
1790                 spin_unlock_bh(&mux->rx_lock);
1791                 return;
1792         }
1793 
1794         if (kcm->rx_wait) {
1795                 list_del(&kcm->wait_rx_list);
1796                 kcm->rx_wait = false;
1797         }
1798         /* Move any pending receive messages to other kcm sockets */
1799         requeue_rx_msgs(mux, &sk->sk_receive_queue);
1800 
1801         spin_unlock_bh(&mux->rx_lock);
1802 
1803         if (WARN_ON(sk_rmem_alloc_get(sk)))
1804                 return;
1805 
1806         /* Detach from MUX */
1807         spin_lock_bh(&mux->lock);
1808 
1809         list_del(&kcm->kcm_sock_list);
1810         mux->kcm_socks_cnt--;
1811         socks_cnt = mux->kcm_socks_cnt;
1812 
1813         spin_unlock_bh(&mux->lock);
1814 
1815         if (!socks_cnt) {
1816                 /* We are done with the mux now. */
1817                 release_mux(mux);
1818         }
1819 
1820         WARN_ON(kcm->rx_wait);
1821 
1822         sock_put(&kcm->sk);
1823 }
1824 
1825 /* Called by kcm_release to close a KCM socket.
1826  * If this is the last KCM socket on the MUX, destroy the MUX.
1827  */
1828 static int kcm_release(struct socket *sock)
1829 {
1830         struct sock *sk = sock->sk;
1831         struct kcm_sock *kcm;
1832         struct kcm_mux *mux;
1833         struct kcm_psock *psock;
1834 
1835         if (!sk)
1836                 return 0;
1837 
1838         kcm = kcm_sk(sk);
1839         mux = kcm->mux;
1840 
1841         sock_orphan(sk);
1842         kfree_skb(kcm->seq_skb);
1843 
1844         lock_sock(sk);
1845         /* Purge queue under lock to avoid race condition with tx_work trying
1846          * to act when queue is nonempty. If tx_work runs after this point
1847          * it will just return.
1848          */
1849         __skb_queue_purge(&sk->sk_write_queue);
1850 
1851         /* Set tx_stopped. This is checked when psock is bound to a kcm and we
1852          * get a writespace callback. This prevents further work being queued
1853          * from the callback (unbinding the psock occurs after canceling work.
1854          */
1855         kcm->tx_stopped = 1;
1856 
1857         release_sock(sk);
1858 
1859         spin_lock_bh(&mux->lock);
1860         if (kcm->tx_wait) {
1861                 /* Take of tx_wait list, after this point there should be no way
1862                  * that a psock will be assigned to this kcm.
1863                  */
1864                 list_del(&kcm->wait_psock_list);
1865                 kcm->tx_wait = false;
1866         }
1867         spin_unlock_bh(&mux->lock);
1868 
1869         /* Cancel work. After this point there should be no outside references
1870          * to the kcm socket.
1871          */
1872         cancel_work_sync(&kcm->tx_work);
1873 
1874         lock_sock(sk);
1875         psock = kcm->tx_psock;
1876         if (psock) {
1877                 /* A psock was reserved, so we need to kill it since it
1878                  * may already have some bytes queued from a message. We
1879                  * need to do this after removing kcm from tx_wait list.
1880                  */
1881                 kcm_abort_tx_psock(psock, EPIPE, false);
1882                 unreserve_psock(kcm);
1883         }
1884         release_sock(sk);
1885 
1886         WARN_ON(kcm->tx_wait);
1887         WARN_ON(kcm->tx_psock);
1888 
1889         sock->sk = NULL;
1890 
1891         kcm_done(kcm);
1892 
1893         return 0;
1894 }
1895 
1896 static const struct proto_ops kcm_dgram_ops = {
1897         .family =       PF_KCM,
1898         .owner =        THIS_MODULE,
1899         .release =      kcm_release,
1900         .bind =         sock_no_bind,
1901         .connect =      sock_no_connect,
1902         .socketpair =   sock_no_socketpair,
1903         .accept =       sock_no_accept,
1904         .getname =      sock_no_getname,
1905         .poll =         datagram_poll,
1906         .ioctl =        kcm_ioctl,
1907         .listen =       sock_no_listen,
1908         .shutdown =     sock_no_shutdown,
1909         .setsockopt =   kcm_setsockopt,
1910         .getsockopt =   kcm_getsockopt,
1911         .sendmsg =      kcm_sendmsg,
1912         .recvmsg =      kcm_recvmsg,
1913         .mmap =         sock_no_mmap,
1914         .sendpage =     kcm_sendpage,
1915 };
1916 
1917 static const struct proto_ops kcm_seqpacket_ops = {
1918         .family =       PF_KCM,
1919         .owner =        THIS_MODULE,
1920         .release =      kcm_release,
1921         .bind =         sock_no_bind,
1922         .connect =      sock_no_connect,
1923         .socketpair =   sock_no_socketpair,
1924         .accept =       sock_no_accept,
1925         .getname =      sock_no_getname,
1926         .poll =         datagram_poll,
1927         .ioctl =        kcm_ioctl,
1928         .listen =       sock_no_listen,
1929         .shutdown =     sock_no_shutdown,
1930         .setsockopt =   kcm_setsockopt,
1931         .getsockopt =   kcm_getsockopt,
1932         .sendmsg =      kcm_sendmsg,
1933         .recvmsg =      kcm_recvmsg,
1934         .mmap =         sock_no_mmap,
1935         .sendpage =     kcm_sendpage,
1936         .splice_read =  kcm_splice_read,
1937 };
1938 
1939 /* Create proto operation for kcm sockets */
1940 static int kcm_create(struct net *net, struct socket *sock,
1941                       int protocol, int kern)
1942 {
1943         struct kcm_net *knet = net_generic(net, kcm_net_id);
1944         struct sock *sk;
1945         struct kcm_mux *mux;
1946 
1947         switch (sock->type) {
1948         case SOCK_DGRAM:
1949                 sock->ops = &kcm_dgram_ops;
1950                 break;
1951         case SOCK_SEQPACKET:
1952                 sock->ops = &kcm_seqpacket_ops;
1953                 break;
1954         default:
1955                 return -ESOCKTNOSUPPORT;
1956         }
1957 
1958         if (protocol != KCMPROTO_CONNECTED)
1959                 return -EPROTONOSUPPORT;
1960 
1961         sk = sk_alloc(net, PF_KCM, GFP_KERNEL, &kcm_proto, kern);
1962         if (!sk)
1963                 return -ENOMEM;
1964 
1965         /* Allocate a kcm mux, shared between KCM sockets */
1966         mux = kmem_cache_zalloc(kcm_muxp, GFP_KERNEL);
1967         if (!mux) {
1968                 sk_free(sk);
1969                 return -ENOMEM;
1970         }
1971 
1972         spin_lock_init(&mux->lock);
1973         spin_lock_init(&mux->rx_lock);
1974         INIT_LIST_HEAD(&mux->kcm_socks);
1975         INIT_LIST_HEAD(&mux->kcm_rx_waiters);
1976         INIT_LIST_HEAD(&mux->kcm_tx_waiters);
1977 
1978         INIT_LIST_HEAD(&mux->psocks);
1979         INIT_LIST_HEAD(&mux->psocks_ready);
1980         INIT_LIST_HEAD(&mux->psocks_avail);
1981 
1982         mux->knet = knet;
1983 
1984         /* Add new MUX to list */
1985         mutex_lock(&knet->mutex);
1986         list_add_rcu(&mux->kcm_mux_list, &knet->mux_list);
1987         knet->count++;
1988         mutex_unlock(&knet->mutex);
1989 
1990         skb_queue_head_init(&mux->rx_hold_queue);
1991 
1992         /* Init KCM socket */
1993         sock_init_data(sock, sk);
1994         init_kcm_sock(kcm_sk(sk), mux);
1995 
1996         return 0;
1997 }
1998 
1999 static const struct net_proto_family kcm_family_ops = {
2000         .family = PF_KCM,
2001         .create = kcm_create,
2002         .owner  = THIS_MODULE,
2003 };
2004 
2005 static __net_init int kcm_init_net(struct net *net)
2006 {
2007         struct kcm_net *knet = net_generic(net, kcm_net_id);
2008 
2009         INIT_LIST_HEAD_RCU(&knet->mux_list);
2010         mutex_init(&knet->mutex);
2011 
2012         return 0;
2013 }
2014 
2015 static __net_exit void kcm_exit_net(struct net *net)
2016 {
2017         struct kcm_net *knet = net_generic(net, kcm_net_id);
2018 
2019         /* All KCM sockets should be closed at this point, which should mean
2020          * that all multiplexors and psocks have been destroyed.
2021          */
2022         WARN_ON(!list_empty(&knet->mux_list));
2023 }
2024 
2025 static struct pernet_operations kcm_net_ops = {
2026         .init = kcm_init_net,
2027         .exit = kcm_exit_net,
2028         .id   = &kcm_net_id,
2029         .size = sizeof(struct kcm_net),
2030 };
2031 
2032 static int __init kcm_init(void)
2033 {
2034         int err = -ENOMEM;
2035 
2036         kcm_muxp = kmem_cache_create("kcm_mux_cache",
2037                                      sizeof(struct kcm_mux), 0,
2038                                      SLAB_HWCACHE_ALIGN, NULL);
2039         if (!kcm_muxp)
2040                 goto fail;
2041 
2042         kcm_psockp = kmem_cache_create("kcm_psock_cache",
2043                                        sizeof(struct kcm_psock), 0,
2044                                         SLAB_HWCACHE_ALIGN, NULL);
2045         if (!kcm_psockp)
2046                 goto fail;
2047 
2048         kcm_wq = create_singlethread_workqueue("kkcmd");
2049         if (!kcm_wq)
2050                 goto fail;
2051 
2052         err = proto_register(&kcm_proto, 1);
2053         if (err)
2054                 goto fail;
2055 
2056         err = register_pernet_device(&kcm_net_ops);
2057         if (err)
2058                 goto net_ops_fail;
2059 
2060         err = sock_register(&kcm_family_ops);
2061         if (err)
2062                 goto sock_register_fail;
2063 
2064         err = kcm_proc_init();
2065         if (err)
2066                 goto proc_init_fail;
2067 
2068         return 0;
2069 
2070 proc_init_fail:
2071         sock_unregister(PF_KCM);
2072 
2073 sock_register_fail:
2074         unregister_pernet_device(&kcm_net_ops);
2075 
2076 net_ops_fail:
2077         proto_unregister(&kcm_proto);
2078 
2079 fail:
2080         kmem_cache_destroy(kcm_muxp);
2081         kmem_cache_destroy(kcm_psockp);
2082 
2083         if (kcm_wq)
2084                 destroy_workqueue(kcm_wq);
2085 
2086         return err;
2087 }
2088 
2089 static void __exit kcm_exit(void)
2090 {
2091         kcm_proc_exit();
2092         sock_unregister(PF_KCM);
2093         unregister_pernet_device(&kcm_net_ops);
2094         proto_unregister(&kcm_proto);
2095         destroy_workqueue(kcm_wq);
2096 
2097         kmem_cache_destroy(kcm_muxp);
2098         kmem_cache_destroy(kcm_psockp);
2099 }
2100 
2101 module_init(kcm_init);
2102 module_exit(kcm_exit);
2103 
2104 MODULE_LICENSE("GPL");
2105 MODULE_ALIAS_NETPROTO(PF_KCM);
2106 

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