net/kcm/kcmsock.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Kernel Connection Multiplexor
   4  *
   5  * Copyright (c) 2016 Tom Herbert <tom@herbertland.com>
   6  */
   7
   8 #include <linux/bpf.h>
   9 #include <linux/errno.h>
  10 #include <linux/errqueue.h>
  11 #include <linux/file.h>
  12 #include <linux/filter.h>
  13 #include <linux/in.h>
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/net.h>
  17 #include <linux/netdevice.h>
  18 #include <linux/poll.h>
  19 #include <linux/rculist.h>
  20 #include <linux/skbuff.h>
  21 #include <linux/socket.h>
  22 #include <linux/uaccess.h>
  23 #include <linux/workqueue.h>
  24 #include <linux/syscalls.h>
  25 #include <linux/sched/signal.h>
  26
  27 #include <net/kcm.h>
  28 #include <net/netns/generic.h>
  29 #include <net/sock.h>
  30 #include <uapi/linux/kcm.h>
  31
  32 unsigned int kcm_net_id;
  33
  34 static struct kmem_cache *kcm_psockp __read_mostly;
  35 static struct kmem_cache *kcm_muxp __read_mostly;
  36 static struct workqueue_struct *kcm_wq;
  37
  38 static inline struct kcm_sock *kcm_sk(const struct sock *sk)
  39 {
  40         return (struct kcm_sock *)sk;
  41 }
  42
  43 static inline struct kcm_tx_msg *kcm_tx_msg(struct sk_buff *skb)
  44 {
  45         return (struct kcm_tx_msg *)skb->cb;
  46 }
  47
  48 static void report_csk_error(struct sock *csk, int err)
  49 {
  50         csk->sk_err = EPIPE;
  51         sk_error_report(csk);
  52 }
  53
  54 static void kcm_abort_tx_psock(struct kcm_psock *psock, int err,
  55                                bool wakeup_kcm)
  56 {
  57         struct sock *csk = psock->sk;
  58         struct kcm_mux *mux = psock->mux;
  59
  60         /* Unrecoverable error in transmit */
  61
  62         spin_lock_bh(&mux->lock);
  63
  64         if (psock->tx_stopped) {
  65                 spin_unlock_bh(&mux->lock);
  66                 return;
  67         }
  68
  69         psock->tx_stopped = 1;
  70         KCM_STATS_INCR(psock->stats.tx_aborts);
  71
  72         if (!psock->tx_kcm) {
  73                 /* Take off psocks_avail list */
  74                 list_del(&psock->psock_avail_list);
  75         } else if (wakeup_kcm) {
  76                 /* In this case psock is being aborted while outside of
  77                  * write_msgs and psock is reserved. Schedule tx_work
  78                  * to handle the failure there. Need to commit tx_stopped
  79                  * before queuing work.
  80                  */
  81                 smp_mb();
  82
  83                 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
  84         }
  85
  86         spin_unlock_bh(&mux->lock);
  87
  88         /* Report error on lower socket */
  89         report_csk_error(csk, err);
  90 }
  91
  92 /* RX mux lock held. */
  93 static void kcm_update_rx_mux_stats(struct kcm_mux *mux,
  94                                     struct kcm_psock *psock)
  95 {
  96         STRP_STATS_ADD(mux->stats.rx_bytes,
  97                        psock->strp.stats.bytes -
  98                        psock->saved_rx_bytes);
  99         mux->stats.rx_msgs +=
 100                 psock->strp.stats.msgs - psock->saved_rx_msgs;
 101         psock->saved_rx_msgs = psock->strp.stats.msgs;
 102         psock->saved_rx_bytes = psock->strp.stats.bytes;
 103 }
 104
 105 static void kcm_update_tx_mux_stats(struct kcm_mux *mux,
 106                                     struct kcm_psock *psock)
 107 {
 108         KCM_STATS_ADD(mux->stats.tx_bytes,
 109                       psock->stats.tx_bytes - psock->saved_tx_bytes);
 110         mux->stats.tx_msgs +=
 111                 psock->stats.tx_msgs - psock->saved_tx_msgs;
 112         psock->saved_tx_msgs = psock->stats.tx_msgs;
 113         psock->saved_tx_bytes = psock->stats.tx_bytes;
 114 }
 115
 116 static int kcm_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
 117
 118 /* KCM is ready to receive messages on its queue-- either the KCM is new or
 119  * has become unblocked after being blocked on full socket buffer. Queue any
 120  * pending ready messages on a psock. RX mux lock held.
 121  */
 122 static void kcm_rcv_ready(struct kcm_sock *kcm)
 123 {
 124         struct kcm_mux *mux = kcm->mux;
 125         struct kcm_psock *psock;
 126         struct sk_buff *skb;
 127
 128         if (unlikely(kcm->rx_wait || kcm->rx_psock || kcm->rx_disabled))
 129                 return;
 130
 131         while (unlikely((skb = __skb_dequeue(&mux->rx_hold_queue)))) {
 132                 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
 133                         /* Assuming buffer limit has been reached */
 134                         skb_queue_head(&mux->rx_hold_queue, skb);
 135                         WARN_ON(!sk_rmem_alloc_get(&kcm->sk));
 136                         return;
 137                 }
 138         }
 139
 140         while (!list_empty(&mux->psocks_ready)) {
 141                 psock = list_first_entry(&mux->psocks_ready, struct kcm_psock,
 142                                          psock_ready_list);
 143
 144                 if (kcm_queue_rcv_skb(&kcm->sk, psock->ready_rx_msg)) {
 145                         /* Assuming buffer limit has been reached */
 146                         WARN_ON(!sk_rmem_alloc_get(&kcm->sk));
 147                         return;
 148                 }
 149
 150                 /* Consumed the ready message on the psock. Schedule rx_work to
 151                  * get more messages.
 152                  */
 153                 list_del(&psock->psock_ready_list);
 154                 psock->ready_rx_msg = NULL;
 155                 /* Commit clearing of ready_rx_msg for queuing work */
 156                 smp_mb();
 157
 158                 strp_unpause(&psock->strp);
 159                 strp_check_rcv(&psock->strp);
 160         }
 161
 162         /* Buffer limit is okay now, add to ready list */
 163         list_add_tail(&kcm->wait_rx_list,
 164                       &kcm->mux->kcm_rx_waiters);
 165         kcm->rx_wait = true;
 166 }
 167
 168 static void kcm_rfree(struct sk_buff *skb)
 169 {
 170         struct sock *sk = skb->sk;
 171         struct kcm_sock *kcm = kcm_sk(sk);
 172         struct kcm_mux *mux = kcm->mux;
 173         unsigned int len = skb->truesize;
 174
 175         sk_mem_uncharge(sk, len);
 176         atomic_sub(len, &sk->sk_rmem_alloc);
 177
 178         /* For reading rx_wait and rx_psock without holding lock */
 179         smp_mb__after_atomic();
 180
 181         if (!kcm->rx_wait && !kcm->rx_psock &&
 182             sk_rmem_alloc_get(sk) < sk->sk_rcvlowat) {
 183                 spin_lock_bh(&mux->rx_lock);
 184                 kcm_rcv_ready(kcm);
 185                 spin_unlock_bh(&mux->rx_lock);
 186         }
 187 }
 188
 189 static int kcm_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 190 {
 191         struct sk_buff_head *list = &sk->sk_receive_queue;
 192
 193         if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
 194                 return -ENOMEM;
 195
 196         if (!sk_rmem_schedule(sk, skb, skb->truesize))
 197                 return -ENOBUFS;
 198
 199         skb->dev = NULL;
 200
 201         skb_orphan(skb);
 202         skb->sk = sk;
 203         skb->destructor = kcm_rfree;
 204         atomic_add(skb->truesize, &sk->sk_rmem_alloc);
 205         sk_mem_charge(sk, skb->truesize);
 206
 207         skb_queue_tail(list, skb);
 208
 209         if (!sock_flag(sk, SOCK_DEAD))
 210                 sk->sk_data_ready(sk);
 211
 212         return 0;
 213 }
 214
 215 /* Requeue received messages for a kcm socket to other kcm sockets. This is
 216  * called with a kcm socket is receive disabled.
 217  * RX mux lock held.
 218  */
 219 static void requeue_rx_msgs(struct kcm_mux *mux, struct sk_buff_head *head)
 220 {
 221         struct sk_buff *skb;
 222         struct kcm_sock *kcm;
 223
 224         while ((skb = __skb_dequeue(head))) {
 225                 /* Reset destructor to avoid calling kcm_rcv_ready */
 226                 skb->destructor = sock_rfree;
 227                 skb_orphan(skb);
 228 try_again:
 229                 if (list_empty(&mux->kcm_rx_waiters)) {
 230                         skb_queue_tail(&mux->rx_hold_queue, skb);
 231                         continue;
 232                 }
 233
 234                 kcm = list_first_entry(&mux->kcm_rx_waiters,
 235                                        struct kcm_sock, wait_rx_list);
 236
 237                 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
 238                         /* Should mean socket buffer full */
 239                         list_del(&kcm->wait_rx_list);
 240                         kcm->rx_wait = false;
 241
 242                         /* Commit rx_wait to read in kcm_free */
 243                         smp_wmb();
 244
 245                         goto try_again;
 246                 }
 247         }
 248 }
 249
 250 /* Lower sock lock held */
 251 static struct kcm_sock *reserve_rx_kcm(struct kcm_psock *psock,
 252                                        struct sk_buff *head)
 253 {
 254         struct kcm_mux *mux = psock->mux;
 255         struct kcm_sock *kcm;
 256
 257         WARN_ON(psock->ready_rx_msg);
 258
 259         if (psock->rx_kcm)
 260                 return psock->rx_kcm;
 261
 262         spin_lock_bh(&mux->rx_lock);
 263
 264         if (psock->rx_kcm) {
 265                 spin_unlock_bh(&mux->rx_lock);
 266                 return psock->rx_kcm;
 267         }
 268
 269         kcm_update_rx_mux_stats(mux, psock);
 270
 271         if (list_empty(&mux->kcm_rx_waiters)) {
 272                 psock->ready_rx_msg = head;
 273                 strp_pause(&psock->strp);
 274                 list_add_tail(&psock->psock_ready_list,
 275                               &mux->psocks_ready);
 276                 spin_unlock_bh(&mux->rx_lock);
 277                 return NULL;
 278         }
 279
 280         kcm = list_first_entry(&mux->kcm_rx_waiters,
 281                                struct kcm_sock, wait_rx_list);
 282         list_del(&kcm->wait_rx_list);
 283         kcm->rx_wait = false;
 284
 285         psock->rx_kcm = kcm;
 286         kcm->rx_psock = psock;
 287
 288         spin_unlock_bh(&mux->rx_lock);
 289
 290         return kcm;
 291 }
 292
 293 static void kcm_done(struct kcm_sock *kcm);
 294
 295 static void kcm_done_work(struct work_struct *w)
 296 {
 297         kcm_done(container_of(w, struct kcm_sock, done_work));
 298 }
 299
 300 /* Lower sock held */
 301 static void unreserve_rx_kcm(struct kcm_psock *psock,
 302                              bool rcv_ready)
 303 {
 304         struct kcm_sock *kcm = psock->rx_kcm;
 305         struct kcm_mux *mux = psock->mux;
 306
 307         if (!kcm)
 308                 return;
 309
 310         spin_lock_bh(&mux->rx_lock);
 311
 312         psock->rx_kcm = NULL;
 313         kcm->rx_psock = NULL;
 314
 315         /* Commit kcm->rx_psock before sk_rmem_alloc_get to sync with
 316          * kcm_rfree
 317          */
 318         smp_mb();
 319
 320         if (unlikely(kcm->done)) {
 321                 spin_unlock_bh(&mux->rx_lock);
 322
 323                 /* Need to run kcm_done in a task since we need to qcquire
 324                  * callback locks which may already be held here.
 325                  */
 326                 INIT_WORK(&kcm->done_work, kcm_done_work);
 327                 schedule_work(&kcm->done_work);
 328                 return;
 329         }
 330
 331         if (unlikely(kcm->rx_disabled)) {
 332                 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
 333         } else if (rcv_ready || unlikely(!sk_rmem_alloc_get(&kcm->sk))) {
 334                 /* Check for degenerative race with rx_wait that all
 335                  * data was dequeued (accounted for in kcm_rfree).
 336                  */
 337                 kcm_rcv_ready(kcm);
 338         }
 339         spin_unlock_bh(&mux->rx_lock);
 340 }
 341
 342 /* Lower sock lock held */
 343 static void psock_data_ready(struct sock *sk)
 344 {
 345         struct kcm_psock *psock;
 346
 347         read_lock_bh(&sk->sk_callback_lock);
 348
 349         psock = (struct kcm_psock *)sk->sk_user_data;
 350         if (likely(psock))
 351                 strp_data_ready(&psock->strp);
 352
 353         read_unlock_bh(&sk->sk_callback_lock);
 354 }
 355
 356 /* Called with lower sock held */
 357 static void kcm_rcv_strparser(struct strparser *strp, struct sk_buff *skb)
 358 {
 359         struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
 360         struct kcm_sock *kcm;
 361
 362 try_queue:
 363         kcm = reserve_rx_kcm(psock, skb);
 364         if (!kcm) {
 365                  /* Unable to reserve a KCM, message is held in psock and strp
 366                   * is paused.
 367                   */
 368                 return;
 369         }
 370
 371         if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
 372                 /* Should mean socket buffer full */
 373                 unreserve_rx_kcm(psock, false);
 374                 goto try_queue;
 375         }
 376 }
 377
 378 static int kcm_parse_func_strparser(struct strparser *strp, struct sk_buff *skb)
 379 {
 380         struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
 381         struct bpf_prog *prog = psock->bpf_prog;
 382         int res;
 383
 384         res = bpf_prog_run_pin_on_cpu(prog, skb);
 385         return res;
 386 }
 387
 388 static int kcm_read_sock_done(struct strparser *strp, int err)
 389 {
 390         struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
 391
 392         unreserve_rx_kcm(psock, true);
 393
 394         return err;
 395 }
 396
 397 static void psock_state_change(struct sock *sk)
 398 {
 399         /* TCP only does a EPOLLIN for a half close. Do a EPOLLHUP here
 400          * since application will normally not poll with EPOLLIN
 401          * on the TCP sockets.
 402          */
 403
 404         report_csk_error(sk, EPIPE);
 405 }
 406
 407 static void psock_write_space(struct sock *sk)
 408 {
 409         struct kcm_psock *psock;
 410         struct kcm_mux *mux;
 411         struct kcm_sock *kcm;
 412
 413         read_lock_bh(&sk->sk_callback_lock);
 414
 415         psock = (struct kcm_psock *)sk->sk_user_data;
 416         if (unlikely(!psock))
 417                 goto out;
 418         mux = psock->mux;
 419
 420         spin_lock_bh(&mux->lock);
 421
 422         /* Check if the socket is reserved so someone is waiting for sending. */
 423         kcm = psock->tx_kcm;
 424         if (kcm && !unlikely(kcm->tx_stopped))
 425                 queue_work(kcm_wq, &kcm->tx_work);
 426
 427         spin_unlock_bh(&mux->lock);
 428 out:
 429         read_unlock_bh(&sk->sk_callback_lock);
 430 }
 431
 432 static void unreserve_psock(struct kcm_sock *kcm);
 433
 434 /* kcm sock is locked. */
 435 static struct kcm_psock *reserve_psock(struct kcm_sock *kcm)
 436 {
 437         struct kcm_mux *mux = kcm->mux;
 438         struct kcm_psock *psock;
 439
 440         psock = kcm->tx_psock;
 441
 442         smp_rmb(); /* Must read tx_psock before tx_wait */
 443
 444         if (psock) {
 445                 WARN_ON(kcm->tx_wait);
 446                 if (unlikely(psock->tx_stopped))
 447                         unreserve_psock(kcm);
 448                 else
 449                         return kcm->tx_psock;
 450         }
 451
 452         spin_lock_bh(&mux->lock);
 453
 454         /* Check again under lock to see if psock was reserved for this
 455          * psock via psock_unreserve.
 456          */
 457         psock = kcm->tx_psock;
 458         if (unlikely(psock)) {
 459                 WARN_ON(kcm->tx_wait);
 460                 spin_unlock_bh(&mux->lock);
 461                 return kcm->tx_psock;
 462         }
 463
 464         if (!list_empty(&mux->psocks_avail)) {
 465                 psock = list_first_entry(&mux->psocks_avail,
 466                                          struct kcm_psock,
 467                                          psock_avail_list);
 468                 list_del(&psock->psock_avail_list);
 469                 if (kcm->tx_wait) {
 470                         list_del(&kcm->wait_psock_list);
 471                         kcm->tx_wait = false;
 472                 }
 473                 kcm->tx_psock = psock;
 474                 psock->tx_kcm = kcm;
 475                 KCM_STATS_INCR(psock->stats.reserved);
 476         } else if (!kcm->tx_wait) {
 477                 list_add_tail(&kcm->wait_psock_list,
 478                               &mux->kcm_tx_waiters);
 479                 kcm->tx_wait = true;
 480         }
 481
 482         spin_unlock_bh(&mux->lock);
 483
 484         return psock;
 485 }
 486
 487 /* mux lock held */
 488 static void psock_now_avail(struct kcm_psock *psock)
 489 {
 490         struct kcm_mux *mux = psock->mux;
 491         struct kcm_sock *kcm;
 492
 493         if (list_empty(&mux->kcm_tx_waiters)) {
 494                 list_add_tail(&psock->psock_avail_list,
 495                               &mux->psocks_avail);
 496         } else {
 497                 kcm = list_first_entry(&mux->kcm_tx_waiters,
 498                                        struct kcm_sock,
 499                                        wait_psock_list);
 500                 list_del(&kcm->wait_psock_list);
 501                 kcm->tx_wait = false;
 502                 psock->tx_kcm = kcm;
 503
 504                 /* Commit before changing tx_psock since that is read in
 505                  * reserve_psock before queuing work.
 506                  */
 507                 smp_mb();
 508
 509                 kcm->tx_psock = psock;
 510                 KCM_STATS_INCR(psock->stats.reserved);
 511                 queue_work(kcm_wq, &kcm->tx_work);
 512         }
 513 }
 514
 515 /* kcm sock is locked. */
 516 static void unreserve_psock(struct kcm_sock *kcm)
 517 {
 518         struct kcm_psock *psock;
 519         struct kcm_mux *mux = kcm->mux;
 520
 521         spin_lock_bh(&mux->lock);
 522
 523         psock = kcm->tx_psock;
 524
 525         if (WARN_ON(!psock)) {
 526                 spin_unlock_bh(&mux->lock);
 527                 return;
 528         }
 529
 530         smp_rmb(); /* Read tx_psock before tx_wait */
 531
 532         kcm_update_tx_mux_stats(mux, psock);
 533
 534         WARN_ON(kcm->tx_wait);
 535
 536         kcm->tx_psock = NULL;
 537         psock->tx_kcm = NULL;
 538         KCM_STATS_INCR(psock->stats.unreserved);
 539
 540         if (unlikely(psock->tx_stopped)) {
 541                 if (psock->done) {
 542                         /* Deferred free */
 543                         list_del(&psock->psock_list);
 544                         mux->psocks_cnt--;
 545                         sock_put(psock->sk);
 546                         fput(psock->sk->sk_socket->file);
 547                         kmem_cache_free(kcm_psockp, psock);
 548                 }
 549
 550                 /* Don't put back on available list */
 551
 552                 spin_unlock_bh(&mux->lock);
 553
 554                 return;
 555         }
 556
 557         psock_now_avail(psock);
 558
 559         spin_unlock_bh(&mux->lock);
 560 }
 561
 562 static void kcm_report_tx_retry(struct kcm_sock *kcm)
 563 {
 564         struct kcm_mux *mux = kcm->mux;
 565
 566         spin_lock_bh(&mux->lock);
 567         KCM_STATS_INCR(mux->stats.tx_retries);
 568         spin_unlock_bh(&mux->lock);
 569 }
 570
 571 /* Write any messages ready on the kcm socket.  Called with kcm sock lock
 572  * held.  Return bytes actually sent or error.
 573  */
 574 static int kcm_write_msgs(struct kcm_sock *kcm)
 575 {
 576         struct sock *sk = &kcm->sk;
 577         struct kcm_psock *psock;
 578         struct sk_buff *skb, *head;
 579         struct kcm_tx_msg *txm;
 580         unsigned short fragidx, frag_offset;
 581         unsigned int sent, total_sent = 0;
 582         int ret = 0;
 583
 584         kcm->tx_wait_more = false;
 585         psock = kcm->tx_psock;
 586         if (unlikely(psock && psock->tx_stopped)) {
 587                 /* A reserved psock was aborted asynchronously. Unreserve
 588                  * it and we'll retry the message.
 589                  */
 590                 unreserve_psock(kcm);
 591                 kcm_report_tx_retry(kcm);
 592                 if (skb_queue_empty(&sk->sk_write_queue))
 593                         return 0;
 594
 595                 kcm_tx_msg(skb_peek(&sk->sk_write_queue))->sent = 0;
 596
 597         } else if (skb_queue_empty(&sk->sk_write_queue)) {
 598                 return 0;
 599         }
 600
 601         head = skb_peek(&sk->sk_write_queue);
 602         txm = kcm_tx_msg(head);
 603
 604         if (txm->sent) {
 605                 /* Send of first skbuff in queue already in progress */
 606                 if (WARN_ON(!psock)) {
 607                         ret = -EINVAL;
 608                         goto out;
 609                 }
 610                 sent = txm->sent;
 611                 frag_offset = txm->frag_offset;
 612                 fragidx = txm->fragidx;
 613                 skb = txm->frag_skb;
 614
 615                 goto do_frag;
 616         }
 617
 618 try_again:
 619         psock = reserve_psock(kcm);
 620         if (!psock)
 621                 goto out;
 622
 623         do {
 624                 skb = head;
 625                 txm = kcm_tx_msg(head);
 626                 sent = 0;
 627
 628 do_frag_list:
 629                 if (WARN_ON(!skb_shinfo(skb)->nr_frags)) {
 630                         ret = -EINVAL;
 631                         goto out;
 632                 }
 633
 634                 for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags;
 635                      fragidx++) {
 636                         skb_frag_t *frag;
 637
 638                         frag_offset = 0;
 639 do_frag:
 640                         frag = &skb_shinfo(skb)->frags[fragidx];
 641                         if (WARN_ON(!skb_frag_size(frag))) {
 642                                 ret = -EINVAL;
 643                                 goto out;
 644                         }
 645
 646                         ret = kernel_sendpage(psock->sk->sk_socket,
 647                                               skb_frag_page(frag),
 648                                               skb_frag_off(frag) + frag_offset,
 649                                               skb_frag_size(frag) - frag_offset,
 650                                               MSG_DONTWAIT);
 651                         if (ret <= 0) {
 652                                 if (ret == -EAGAIN) {
 653                                         /* Save state to try again when there's
 654                                          * write space on the socket
 655                                          */
 656                                         txm->sent = sent;
 657                                         txm->frag_offset = frag_offset;
 658                                         txm->fragidx = fragidx;
 659                                         txm->frag_skb = skb;
 660
 661                                         ret = 0;
 662                                         goto out;
 663                                 }
 664
 665                                 /* Hard failure in sending message, abort this
 666                                  * psock since it has lost framing
 667                                  * synchronization and retry sending the
 668                                  * message from the beginning.
 669                                  */
 670                                 kcm_abort_tx_psock(psock, ret ? -ret : EPIPE,
 671                                                    true);
 672                                 unreserve_psock(kcm);
 673
 674                                 txm->sent = 0;
 675                                 kcm_report_tx_retry(kcm);
 676                                 ret = 0;
 677
 678                                 goto try_again;
 679                         }
 680
 681                         sent += ret;
 682                         frag_offset += ret;
 683                         KCM_STATS_ADD(psock->stats.tx_bytes, ret);
 684                         if (frag_offset < skb_frag_size(frag)) {
 685                                 /* Not finished with this frag */
 686                                 goto do_frag;
 687                         }
 688                 }
 689
 690                 if (skb == head) {
 691                         if (skb_has_frag_list(skb)) {
 692                                 skb = skb_shinfo(skb)->frag_list;
 693                                 goto do_frag_list;
 694                         }
 695                 } else if (skb->next) {
 696                         skb = skb->next;
 697                         goto do_frag_list;
 698                 }
 699
 700                 /* Successfully sent the whole packet, account for it. */
 701                 skb_dequeue(&sk->sk_write_queue);
 702                 kfree_skb(head);
 703                 sk->sk_wmem_queued -= sent;
 704                 total_sent += sent;
 705                 KCM_STATS_INCR(psock->stats.tx_msgs);
 706         } while ((head = skb_peek(&sk->sk_write_queue)));
 707 out:
 708         if (!head) {
 709                 /* Done with all queued messages. */
 710                 WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
 711                 unreserve_psock(kcm);
 712         }
 713
 714         /* Check if write space is available */
 715         sk->sk_write_space(sk);
 716
 717         return total_sent ? : ret;
 718 }
 719
 720 static void kcm_tx_work(struct work_struct *w)
 721 {
 722         struct kcm_sock *kcm = container_of(w, struct kcm_sock, tx_work);
 723         struct sock *sk = &kcm->sk;
 724         int err;
 725
 726         lock_sock(sk);
 727
 728         /* Primarily for SOCK_DGRAM sockets, also handle asynchronous tx
 729          * aborts
 730          */
 731         err = kcm_write_msgs(kcm);
 732         if (err < 0) {
 733                 /* Hard failure in write, report error on KCM socket */
 734                 pr_warn("KCM: Hard failure on kcm_write_msgs %d\n", err);
 735                 report_csk_error(&kcm->sk, -err);
 736                 goto out;
 737         }
 738
 739         /* Primarily for SOCK_SEQPACKET sockets */
 740         if (likely(sk->sk_socket) &&
 741             test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
 742                 clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 743                 sk->sk_write_space(sk);
 744         }
 745
 746 out:
 747         release_sock(sk);
 748 }
 749
 750 static void kcm_push(struct kcm_sock *kcm)
 751 {
 752         if (kcm->tx_wait_more)
 753                 kcm_write_msgs(kcm);
 754 }
 755
 756 static ssize_t kcm_sendpage(struct socket *sock, struct page *page,
 757                             int offset, size_t size, int flags)
 758
 759 {
 760         struct sock *sk = sock->sk;
 761         struct kcm_sock *kcm = kcm_sk(sk);
 762         struct sk_buff *skb = NULL, *head = NULL;
 763         long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 764         bool eor;
 765         int err = 0;
 766         int i;
 767
 768         if (flags & MSG_SENDPAGE_NOTLAST)
 769                 flags |= MSG_MORE;
 770
 771         /* No MSG_EOR from splice, only look at MSG_MORE */
 772         eor = !(flags & MSG_MORE);
 773
 774         lock_sock(sk);
 775
 776         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 777
 778         err = -EPIPE;
 779         if (sk->sk_err)
 780                 goto out_error;
 781
 782         if (kcm->seq_skb) {
 783                 /* Previously opened message */
 784                 head = kcm->seq_skb;
 785                 skb = kcm_tx_msg(head)->last_skb;
 786                 i = skb_shinfo(skb)->nr_frags;
 787
 788                 if (skb_can_coalesce(skb, i, page, offset)) {
 789                         skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
 790                         skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
 791                         goto coalesced;
 792                 }
 793
 794                 if (i >= MAX_SKB_FRAGS) {
 795                         struct sk_buff *tskb;
 796
 797                         tskb = alloc_skb(0, sk->sk_allocation);
 798                         while (!tskb) {
 799                                 kcm_push(kcm);
 800                                 err = sk_stream_wait_memory(sk, &timeo);
 801                                 if (err)
 802                                         goto out_error;
 803                         }
 804
 805                         if (head == skb)
 806                                 skb_shinfo(head)->frag_list = tskb;
 807                         else
 808                                 skb->next = tskb;
 809
 810                         skb = tskb;
 811                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 812                         i = 0;
 813                 }
 814         } else {
 815                 /* Call the sk_stream functions to manage the sndbuf mem. */
 816                 if (!sk_stream_memory_free(sk)) {
 817                         kcm_push(kcm);
 818                         set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 819                         err = sk_stream_wait_memory(sk, &timeo);
 820                         if (err)
 821                                 goto out_error;
 822                 }
 823
 824                 head = alloc_skb(0, sk->sk_allocation);
 825                 while (!head) {
 826                         kcm_push(kcm);
 827                         err = sk_stream_wait_memory(sk, &timeo);
 828                         if (err)
 829                                 goto out_error;
 830                 }
 831
 832                 skb = head;
 833                 i = 0;
 834         }
 835
 836         get_page(page);
 837         skb_fill_page_desc(skb, i, page, offset, size);
 838         skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
 839
 840 coalesced:
 841         skb->len += size;
 842         skb->data_len += size;
 843         skb->truesize += size;
 844         sk->sk_wmem_queued += size;
 845         sk_mem_charge(sk, size);
 846
 847         if (head != skb) {
 848                 head->len += size;
 849                 head->data_len += size;
 850                 head->truesize += size;
 851         }
 852
 853         if (eor) {
 854                 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
 855
 856                 /* Message complete, queue it on send buffer */
 857                 __skb_queue_tail(&sk->sk_write_queue, head);
 858                 kcm->seq_skb = NULL;
 859                 KCM_STATS_INCR(kcm->stats.tx_msgs);
 860
 861                 if (flags & MSG_BATCH) {
 862                         kcm->tx_wait_more = true;
 863                 } else if (kcm->tx_wait_more || not_busy) {
 864                         err = kcm_write_msgs(kcm);
 865                         if (err < 0) {
 866                                 /* We got a hard error in write_msgs but have
 867                                  * already queued this message. Report an error
 868                                  * in the socket, but don't affect return value
 869                                  * from sendmsg
 870                                  */
 871                                 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
 872                                 report_csk_error(&kcm->sk, -err);
 873                         }
 874                 }
 875         } else {
 876                 /* Message not complete, save state */
 877                 kcm->seq_skb = head;
 878                 kcm_tx_msg(head)->last_skb = skb;
 879         }
 880
 881         KCM_STATS_ADD(kcm->stats.tx_bytes, size);
 882
 883         release_sock(sk);
 884         return size;
 885
 886 out_error:
 887         kcm_push(kcm);
 888
 889         err = sk_stream_error(sk, flags, err);
 890
 891         /* make sure we wake any epoll edge trigger waiter */
 892         if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
 893                 sk->sk_write_space(sk);
 894
 895         release_sock(sk);
 896         return err;
 897 }
 898
 899 static int kcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 900 {
 901         struct sock *sk = sock->sk;
 902         struct kcm_sock *kcm = kcm_sk(sk);
 903         struct sk_buff *skb = NULL, *head = NULL;
 904         size_t copy, copied = 0;
 905         long timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
 906         int eor = (sock->type == SOCK_DGRAM) ?
 907                   !(msg->msg_flags & MSG_MORE) : !!(msg->msg_flags & MSG_EOR);
 908         int err = -EPIPE;
 909
 910         lock_sock(sk);
 911
 912         /* Per tcp_sendmsg this should be in poll */
 913         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 914
 915         if (sk->sk_err)
 916                 goto out_error;
 917
 918         if (kcm->seq_skb) {
 919                 /* Previously opened message */
 920                 head = kcm->seq_skb;
 921                 skb = kcm_tx_msg(head)->last_skb;
 922                 goto start;
 923         }
 924
 925         /* Call the sk_stream functions to manage the sndbuf mem. */
 926         if (!sk_stream_memory_free(sk)) {
 927                 kcm_push(kcm);
 928                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 929                 err = sk_stream_wait_memory(sk, &timeo);
 930                 if (err)
 931                         goto out_error;
 932         }
 933
 934         if (msg_data_left(msg)) {
 935                 /* New message, alloc head skb */
 936                 head = alloc_skb(0, sk->sk_allocation);
 937                 while (!head) {
 938                         kcm_push(kcm);
 939                         err = sk_stream_wait_memory(sk, &timeo);
 940                         if (err)
 941                                 goto out_error;
 942
 943                         head = alloc_skb(0, sk->sk_allocation);
 944                 }
 945
 946                 skb = head;
 947
 948                 /* Set ip_summed to CHECKSUM_UNNECESSARY to avoid calling
 949                  * csum_and_copy_from_iter from skb_do_copy_data_nocache.
 950                  */
 951                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 952         }
 953
 954 start:
 955         while (msg_data_left(msg)) {
 956                 bool merge = true;
 957                 int i = skb_shinfo(skb)->nr_frags;
 958                 struct page_frag *pfrag = sk_page_frag(sk);
 959
 960                 if (!sk_page_frag_refill(sk, pfrag))
 961                         goto wait_for_memory;
 962
 963                 if (!skb_can_coalesce(skb, i, pfrag->page,
 964                                       pfrag->offset)) {
 965                         if (i == MAX_SKB_FRAGS) {
 966                                 struct sk_buff *tskb;
 967
 968                                 tskb = alloc_skb(0, sk->sk_allocation);
 969                                 if (!tskb)
 970                                         goto wait_for_memory;
 971
 972                                 if (head == skb)
 973                                         skb_shinfo(head)->frag_list = tskb;
 974                                 else
 975                                         skb->next = tskb;
 976
 977                                 skb = tskb;
 978                                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 979                                 continue;
 980                         }
 981                         merge = false;
 982                 }
 983
 984                 copy = min_t(int, msg_data_left(msg),
 985                              pfrag->size - pfrag->offset);
 986
 987                 if (!sk_wmem_schedule(sk, copy))
 988                         goto wait_for_memory;
 989
 990                 err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
 991                                                pfrag->page,
 992                                                pfrag->offset,
 993                                                copy);
 994                 if (err)
 995                         goto out_error;
 996
 997                 /* Update the skb. */
 998                 if (merge) {
 999                         skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1000                 } else {
1001                         skb_fill_page_desc(skb, i, pfrag->page,
1002                                            pfrag->offset, copy);
1003                         get_page(pfrag->page);
1004                 }
1005
1006                 pfrag->offset += copy;
1007                 copied += copy;
1008                 if (head != skb) {
1009                         head->len += copy;
1010                         head->data_len += copy;
1011                 }
1012
1013                 continue;
1014
1015 wait_for_memory:
1016                 kcm_push(kcm);
1017                 err = sk_stream_wait_memory(sk, &timeo);
1018                 if (err)
1019                         goto out_error;
1020         }
1021
1022         if (eor) {
1023                 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
1024
1025                 if (head) {
1026                         /* Message complete, queue it on send buffer */
1027                         __skb_queue_tail(&sk->sk_write_queue, head);
1028                         kcm->seq_skb = NULL;
1029                         KCM_STATS_INCR(kcm->stats.tx_msgs);
1030                 }
1031
1032                 if (msg->msg_flags & MSG_BATCH) {
1033                         kcm->tx_wait_more = true;
1034                 } else if (kcm->tx_wait_more || not_busy) {
1035                         err = kcm_write_msgs(kcm);
1036                         if (err < 0) {
1037                                 /* We got a hard error in write_msgs but have
1038                                  * already queued this message. Report an error
1039                                  * in the socket, but don't affect return value
1040                                  * from sendmsg
1041                                  */
1042                                 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
1043                                 report_csk_error(&kcm->sk, -err);
1044                         }
1045                 }
1046         } else {
1047                 /* Message not complete, save state */
1048 partial_message:
1049                 if (head) {
1050                         kcm->seq_skb = head;
1051                         kcm_tx_msg(head)->last_skb = skb;
1052                 }
1053         }
1054
1055         KCM_STATS_ADD(kcm->stats.tx_bytes, copied);
1056
1057         release_sock(sk);
1058         return copied;
1059
1060 out_error:
1061         kcm_push(kcm);
1062
1063         if (copied && sock->type == SOCK_SEQPACKET) {
1064                 /* Wrote some bytes before encountering an
1065                  * error, return partial success.
1066                  */
1067                 goto partial_message;
1068         }
1069
1070         if (head != kcm->seq_skb)
1071                 kfree_skb(head);
1072
1073         err = sk_stream_error(sk, msg->msg_flags, err);
1074
1075         /* make sure we wake any epoll edge trigger waiter */
1076         if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
1077                 sk->sk_write_space(sk);
1078
1079         release_sock(sk);
1080         return err;
1081 }
1082
1083 static struct sk_buff *kcm_wait_data(struct sock *sk, int flags,
1084                                      long timeo, int *err)
1085 {
1086         struct sk_buff *skb;
1087
1088         while (!(skb = skb_peek(&sk->sk_receive_queue))) {
1089                 if (sk->sk_err) {
1090                         *err = sock_error(sk);
1091                         return NULL;
1092                 }
1093
1094                 if (sock_flag(sk, SOCK_DONE))
1095                         return NULL;
1096
1097                 if ((flags & MSG_DONTWAIT) || !timeo) {
1098                         *err = -EAGAIN;
1099                         return NULL;
1100                 }
1101
1102                 sk_wait_data(sk, &timeo, NULL);
1103
1104                 /* Handle signals */
1105                 if (signal_pending(current)) {
1106                         *err = sock_intr_errno(timeo);
1107                         return NULL;
1108                 }
1109         }
1110
1111         return skb;
1112 }
1113
1114 static int kcm_recvmsg(struct socket *sock, struct msghdr *msg,
1115                        size_t len, int flags)
1116 {
1117         struct sock *sk = sock->sk;
1118         struct kcm_sock *kcm = kcm_sk(sk);
1119         int err = 0;
1120         long timeo;
1121         struct strp_msg *stm;
1122         int copied = 0;
1123         struct sk_buff *skb;
1124
1125         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
1126
1127         lock_sock(sk);
1128
1129         skb = kcm_wait_data(sk, flags, timeo, &err);
1130         if (!skb)
1131                 goto out;
1132
1133         /* Okay, have a message on the receive queue */
1134
1135         stm = strp_msg(skb);
1136
1137         if (len > stm->full_len)
1138                 len = stm->full_len;
1139
1140         err = skb_copy_datagram_msg(skb, stm->offset, msg, len);
1141         if (err < 0)
1142                 goto out;
1143
1144         copied = len;
1145         if (likely(!(flags & MSG_PEEK))) {
1146                 KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1147                 if (copied < stm->full_len) {
1148                         if (sock->type == SOCK_DGRAM) {
1149                                 /* Truncated message */
1150                                 msg->msg_flags |= MSG_TRUNC;
1151                                 goto msg_finished;
1152                         }
1153                         stm->offset += copied;
1154                         stm->full_len -= copied;
1155                 } else {
1156 msg_finished:
1157                         /* Finished with message */
1158                         msg->msg_flags |= MSG_EOR;
1159                         KCM_STATS_INCR(kcm->stats.rx_msgs);
1160                         skb_unlink(skb, &sk->sk_receive_queue);
1161                         kfree_skb(skb);
1162                 }
1163         }
1164
1165 out:
1166         release_sock(sk);
1167
1168         return copied ? : err;
1169 }
1170
1171 static ssize_t kcm_splice_read(struct socket *sock, loff_t *ppos,
1172                                struct pipe_inode_info *pipe, size_t len,
1173                                unsigned int flags)
1174 {
1175         struct sock *sk = sock->sk;
1176         struct kcm_sock *kcm = kcm_sk(sk);
1177         long timeo;
1178         struct strp_msg *stm;
1179         int err = 0;
1180         ssize_t copied;
1181         struct sk_buff *skb;
1182
1183         /* Only support splice for SOCKSEQPACKET */
1184
1185         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
1186
1187         lock_sock(sk);
1188
1189         skb = kcm_wait_data(sk, flags, timeo, &err);
1190         if (!skb)
1191                 goto err_out;
1192
1193         /* Okay, have a message on the receive queue */
1194
1195         stm = strp_msg(skb);
1196
1197         if (len > stm->full_len)
1198                 len = stm->full_len;
1199
1200         copied = skb_splice_bits(skb, sk, stm->offset, pipe, len, flags);
1201         if (copied < 0) {
1202                 err = copied;
1203                 goto err_out;
1204         }
1205
1206         KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1207
1208         stm->offset += copied;
1209         stm->full_len -= copied;
1210
1211         /* We have no way to return MSG_EOR. If all the bytes have been
1212          * read we still leave the message in the receive socket buffer.
1213          * A subsequent recvmsg needs to be done to return MSG_EOR and
1214          * finish reading the message.
1215          */
1216
1217         release_sock(sk);
1218
1219         return copied;
1220
1221 err_out:
1222         release_sock(sk);
1223
1224         return err;
1225 }
1226
1227 /* kcm sock lock held */
1228 static void kcm_recv_disable(struct kcm_sock *kcm)
1229 {
1230         struct kcm_mux *mux = kcm->mux;
1231
1232         if (kcm->rx_disabled)
1233                 return;
1234
1235         spin_lock_bh(&mux->rx_lock);
1236
1237         kcm->rx_disabled = 1;
1238
1239         /* If a psock is reserved we'll do cleanup in unreserve */
1240         if (!kcm->rx_psock) {
1241                 if (kcm->rx_wait) {
1242                         list_del(&kcm->wait_rx_list);
1243                         kcm->rx_wait = false;
1244                 }
1245
1246                 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
1247         }
1248
1249         spin_unlock_bh(&mux->rx_lock);
1250 }
1251
1252 /* kcm sock lock held */
1253 static void kcm_recv_enable(struct kcm_sock *kcm)
1254 {
1255         struct kcm_mux *mux = kcm->mux;
1256
1257         if (!kcm->rx_disabled)
1258                 return;
1259
1260         spin_lock_bh(&mux->rx_lock);
1261
1262         kcm->rx_disabled = 0;
1263         kcm_rcv_ready(kcm);
1264
1265         spin_unlock_bh(&mux->rx_lock);
1266 }
1267
1268 static int kcm_setsockopt(struct socket *sock, int level, int optname,
1269                           sockptr_t optval, unsigned int optlen)
1270 {
1271         struct kcm_sock *kcm = kcm_sk(sock->sk);
1272         int val, valbool;
1273         int err = 0;
1274
1275         if (level != SOL_KCM)
1276                 return -ENOPROTOOPT;
1277
1278         if (optlen < sizeof(int))
1279                 return -EINVAL;
1280
1281         if (copy_from_sockptr(&val, optval, sizeof(int)))
1282                 return -EFAULT;
1283
1284         valbool = val ? 1 : 0;
1285
1286         switch (optname) {
1287         case KCM_RECV_DISABLE:
1288                 lock_sock(&kcm->sk);
1289                 if (valbool)
1290                         kcm_recv_disable(kcm);
1291                 else
1292                         kcm_recv_enable(kcm);
1293                 release_sock(&kcm->sk);
1294                 break;
1295         default:
1296                 err = -ENOPROTOOPT;
1297         }
1298
1299         return err;
1300 }
1301
1302 static int kcm_getsockopt(struct socket *sock, int level, int optname,
1303                           char __user *optval, int __user *optlen)
1304 {
1305         struct kcm_sock *kcm = kcm_sk(sock->sk);
1306         int val, len;
1307
1308         if (level != SOL_KCM)
1309                 return -ENOPROTOOPT;
1310
1311         if (get_user(len, optlen))
1312                 return -EFAULT;
1313
1314         len = min_t(unsigned int, len, sizeof(int));
1315         if (len < 0)
1316                 return -EINVAL;
1317
1318         switch (optname) {
1319         case KCM_RECV_DISABLE:
1320                 val = kcm->rx_disabled;
1321                 break;
1322         default:
1323                 return -ENOPROTOOPT;
1324         }
1325
1326         if (put_user(len, optlen))
1327                 return -EFAULT;
1328         if (copy_to_user(optval, &val, len))
1329                 return -EFAULT;
1330         return 0;
1331 }
1332
1333 static void init_kcm_sock(struct kcm_sock *kcm, struct kcm_mux *mux)
1334 {
1335         struct kcm_sock *tkcm;
1336         struct list_head *head;
1337         int index = 0;
1338
1339         /* For SOCK_SEQPACKET sock type, datagram_poll checks the sk_state, so
1340          * we set sk_state, otherwise epoll_wait always returns right away with
1341          * EPOLLHUP
1342          */
1343         kcm->sk.sk_state = TCP_ESTABLISHED;
1344
1345         /* Add to mux's kcm sockets list */
1346         kcm->mux = mux;
1347         spin_lock_bh(&mux->lock);
1348
1349         head = &mux->kcm_socks;
1350         list_for_each_entry(tkcm, &mux->kcm_socks, kcm_sock_list) {
1351                 if (tkcm->index != index)
1352                         break;
1353                 head = &tkcm->kcm_sock_list;
1354                 index++;
1355         }
1356
1357         list_add(&kcm->kcm_sock_list, head);
1358         kcm->index = index;
1359
1360         mux->kcm_socks_cnt++;
1361         spin_unlock_bh(&mux->lock);
1362
1363         INIT_WORK(&kcm->tx_work, kcm_tx_work);
1364
1365         spin_lock_bh(&mux->rx_lock);
1366         kcm_rcv_ready(kcm);
1367         spin_unlock_bh(&mux->rx_lock);
1368 }
1369
1370 static int kcm_attach(struct socket *sock, struct socket *csock,
1371                       struct bpf_prog *prog)
1372 {
1373         struct kcm_sock *kcm = kcm_sk(sock->sk);
1374         struct kcm_mux *mux = kcm->mux;
1375         struct sock *csk;
1376         struct kcm_psock *psock = NULL, *tpsock;
1377         struct list_head *head;
1378         int index = 0;
1379         static const struct strp_callbacks cb = {
1380                 .rcv_msg = kcm_rcv_strparser,
1381                 .parse_msg = kcm_parse_func_strparser,
1382                 .read_sock_done = kcm_read_sock_done,
1383         };
1384         int err = 0;
1385
1386         csk = csock->sk;
1387         if (!csk)
1388                 return -EINVAL;
1389
1390         lock_sock(csk);
1391
1392         /* Only allow TCP sockets to be attached for now */
1393         if ((csk->sk_family != AF_INET && csk->sk_family != AF_INET6) ||
1394             csk->sk_protocol != IPPROTO_TCP) {
1395                 err = -EOPNOTSUPP;
1396                 goto out;
1397         }
1398
1399         /* Don't allow listeners or closed sockets */
1400         if (csk->sk_state == TCP_LISTEN || csk->sk_state == TCP_CLOSE) {
1401                 err = -EOPNOTSUPP;
1402                 goto out;
1403         }
1404
1405         psock = kmem_cache_zalloc(kcm_psockp, GFP_KERNEL);
1406         if (!psock) {
1407                 err = -ENOMEM;
1408                 goto out;
1409         }
1410
1411         psock->mux = mux;
1412         psock->sk = csk;
1413         psock->bpf_prog = prog;
1414
1415         write_lock_bh(&csk->sk_callback_lock);
1416
1417         /* Check if sk_user_data is already by KCM or someone else.
1418          * Must be done under lock to prevent race conditions.
1419          */
1420         if (csk->sk_user_data) {
1421                 write_unlock_bh(&csk->sk_callback_lock);
1422                 kmem_cache_free(kcm_psockp, psock);
1423                 err = -EALREADY;
1424                 goto out;
1425         }
1426
1427         err = strp_init(&psock->strp, csk, &cb);
1428         if (err) {
1429                 write_unlock_bh(&csk->sk_callback_lock);
1430                 kmem_cache_free(kcm_psockp, psock);
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         sockfd_put(csock);
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         sockfd_put(csock);
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);