net/kcm/kcmsock.c

   1 /*
   2  * Kernel Connection Multiplexor
   3  *
   4  * Copyright (c) 2016 Tom Herbert <tom@herbertland.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2
   8  * as published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/bpf.h>
  12 #include <linux/errno.h>
  13 #include <linux/errqueue.h>
  14 #include <linux/file.h>
  15 #include <linux/in.h>
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/net.h>
  19 #include <linux/netdevice.h>
  20 #include <linux/poll.h>
  21 #include <linux/rculist.h>
  22 #include <linux/skbuff.h>
  23 #include <linux/socket.h>
  24 #include <linux/uaccess.h>
  25 #include <linux/workqueue.h>
  26 #include <linux/syscalls.h>
  27 #include <linux/sched/signal.h>
  28
  29 #include <net/kcm.h>
  30 #include <net/netns/generic.h>
  31 #include <net/sock.h>
  32 #include <uapi/linux/kcm.h>
  33
  34 unsigned int kcm_net_id;
  35
  36 static struct kmem_cache *kcm_psockp __read_mostly;
  37 static struct kmem_cache *kcm_muxp __read_mostly;
  38 static struct workqueue_struct *kcm_wq;
  39
  40 static inline struct kcm_sock *kcm_sk(const struct sock *sk)
  41 {
  42         return (struct kcm_sock *)sk;
  43 }
  44
  45 static inline struct kcm_tx_msg *kcm_tx_msg(struct sk_buff *skb)
  46 {
  47         return (struct kcm_tx_msg *)skb->cb;
  48 }
  49
  50 static void report_csk_error(struct sock *csk, int err)
  51 {
  52         csk->sk_err = EPIPE;
  53         csk->sk_error_report(csk);
  54 }
  55
  56 static void kcm_abort_tx_psock(struct kcm_psock *psock, int err,
  57                                bool wakeup_kcm)
  58 {
  59         struct sock *csk = psock->sk;
  60         struct kcm_mux *mux = psock->mux;
  61
  62         /* Unrecoverable error in transmit */
  63
  64         spin_lock_bh(&mux->lock);
  65
  66         if (psock->tx_stopped) {
  67                 spin_unlock_bh(&mux->lock);
  68                 return;
  69         }
  70
  71         psock->tx_stopped = 1;
  72         KCM_STATS_INCR(psock->stats.tx_aborts);
  73
  74         if (!psock->tx_kcm) {
  75                 /* Take off psocks_avail list */
  76                 list_del(&psock->psock_avail_list);
  77         } else if (wakeup_kcm) {
  78                 /* In this case psock is being aborted while outside of
  79                  * write_msgs and psock is reserved. Schedule tx_work
  80                  * to handle the failure there. Need to commit tx_stopped
  81                  * before queuing work.
  82                  */
  83                 smp_mb();
  84
  85                 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
  86         }
  87
  88         spin_unlock_bh(&mux->lock);
  89
  90         /* Report error on lower socket */
  91         report_csk_error(csk, err);
  92 }
  93
  94 /* RX mux lock held. */
  95 static void kcm_update_rx_mux_stats(struct kcm_mux *mux,
  96                                     struct kcm_psock *psock)
  97 {
  98         STRP_STATS_ADD(mux->stats.rx_bytes,
  99                        psock->strp.stats.rx_bytes -
 100                        psock->saved_rx_bytes);
 101         mux->stats.rx_msgs +=
 102                 psock->strp.stats.rx_msgs - psock->saved_rx_msgs;
 103         psock->saved_rx_msgs = psock->strp.stats.rx_msgs;
 104         psock->saved_rx_bytes = psock->strp.stats.rx_bytes;
 105 }
 106
 107 static void kcm_update_tx_mux_stats(struct kcm_mux *mux,
 108                                     struct kcm_psock *psock)
 109 {
 110         KCM_STATS_ADD(mux->stats.tx_bytes,
 111                       psock->stats.tx_bytes - psock->saved_tx_bytes);
 112         mux->stats.tx_msgs +=
 113                 psock->stats.tx_msgs - psock->saved_tx_msgs;
 114         psock->saved_tx_msgs = psock->stats.tx_msgs;
 115         psock->saved_tx_bytes = psock->stats.tx_bytes;
 116 }
 117
 118 static int kcm_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
 119
 120 /* KCM is ready to receive messages on its queue-- either the KCM is new or
 121  * has become unblocked after being blocked on full socket buffer. Queue any
 122  * pending ready messages on a psock. RX mux lock held.
 123  */
 124 static void kcm_rcv_ready(struct kcm_sock *kcm)
 125 {
 126         struct kcm_mux *mux = kcm->mux;
 127         struct kcm_psock *psock;
 128         struct sk_buff *skb;
 129
 130         if (unlikely(kcm->rx_wait || kcm->rx_psock || kcm->rx_disabled))
 131                 return;
 132
 133         while (unlikely((skb = __skb_dequeue(&mux->rx_hold_queue)))) {
 134                 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
 135                         /* Assuming buffer limit has been reached */
 136                         skb_queue_head(&mux->rx_hold_queue, skb);
 137                         WARN_ON(!sk_rmem_alloc_get(&kcm->sk));
 138                         return;
 139                 }
 140         }
 141
 142         while (!list_empty(&mux->psocks_ready)) {
 143                 psock = list_first_entry(&mux->psocks_ready, struct kcm_psock,
 144                                          psock_ready_list);
 145
 146                 if (kcm_queue_rcv_skb(&kcm->sk, psock->ready_rx_msg)) {
 147                         /* Assuming buffer limit has been reached */
 148                         WARN_ON(!sk_rmem_alloc_get(&kcm->sk));
 149                         return;
 150                 }
 151
 152                 /* Consumed the ready message on the psock. Schedule rx_work to
 153                  * get more messages.
 154                  */
 155                 list_del(&psock->psock_ready_list);
 156                 psock->ready_rx_msg = NULL;
 157                 /* Commit clearing of ready_rx_msg for queuing work */
 158                 smp_mb();
 159
 160                 strp_unpause(&psock->strp);
 161                 strp_check_rcv(&psock->strp);
 162         }
 163
 164         /* Buffer limit is okay now, add to ready list */
 165         list_add_tail(&kcm->wait_rx_list,
 166                       &kcm->mux->kcm_rx_waiters);
 167         kcm->rx_wait = true;
 168 }
 169
 170 static void kcm_rfree(struct sk_buff *skb)
 171 {
 172         struct sock *sk = skb->sk;
 173         struct kcm_sock *kcm = kcm_sk(sk);
 174         struct kcm_mux *mux = kcm->mux;
 175         unsigned int len = skb->truesize;
 176
 177         sk_mem_uncharge(sk, len);
 178         atomic_sub(len, &sk->sk_rmem_alloc);
 179
 180         /* For reading rx_wait and rx_psock without holding lock */
 181         smp_mb__after_atomic();
 182
 183         if (!kcm->rx_wait && !kcm->rx_psock &&
 184             sk_rmem_alloc_get(sk) < sk->sk_rcvlowat) {
 185                 spin_lock_bh(&mux->rx_lock);
 186                 kcm_rcv_ready(kcm);
 187                 spin_unlock_bh(&mux->rx_lock);
 188         }
 189 }
 190
 191 static int kcm_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 192 {
 193         struct sk_buff_head *list = &sk->sk_receive_queue;
 194
 195         if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
 196                 return -ENOMEM;
 197
 198         if (!sk_rmem_schedule(sk, skb, skb->truesize))
 199                 return -ENOBUFS;
 200
 201         skb->dev = NULL;
 202
 203         skb_orphan(skb);
 204         skb->sk = sk;
 205         skb->destructor = kcm_rfree;
 206         atomic_add(skb->truesize, &sk->sk_rmem_alloc);
 207         sk_mem_charge(sk, skb->truesize);
 208
 209         skb_queue_tail(list, skb);
 210
 211         if (!sock_flag(sk, SOCK_DEAD))
 212                 sk->sk_data_ready(sk);
 213
 214         return 0;
 215 }
 216
 217 /* Requeue received messages for a kcm socket to other kcm sockets. This is
 218  * called with a kcm socket is receive disabled.
 219  * RX mux lock held.
 220  */
 221 static void requeue_rx_msgs(struct kcm_mux *mux, struct sk_buff_head *head)
 222 {
 223         struct sk_buff *skb;
 224         struct kcm_sock *kcm;
 225
 226         while ((skb = __skb_dequeue(head))) {
 227                 /* Reset destructor to avoid calling kcm_rcv_ready */
 228                 skb->destructor = sock_rfree;
 229                 skb_orphan(skb);
 230 try_again:
 231                 if (list_empty(&mux->kcm_rx_waiters)) {
 232                         skb_queue_tail(&mux->rx_hold_queue, skb);
 233                         continue;
 234                 }
 235
 236                 kcm = list_first_entry(&mux->kcm_rx_waiters,
 237                                        struct kcm_sock, wait_rx_list);
 238
 239                 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
 240                         /* Should mean socket buffer full */
 241                         list_del(&kcm->wait_rx_list);
 242                         kcm->rx_wait = false;
 243
 244                         /* Commit rx_wait to read in kcm_free */
 245                         smp_wmb();
 246
 247                         goto try_again;
 248                 }
 249         }
 250 }
 251
 252 /* Lower sock lock held */
 253 static struct kcm_sock *reserve_rx_kcm(struct kcm_psock *psock,
 254                                        struct sk_buff *head)
 255 {
 256         struct kcm_mux *mux = psock->mux;
 257         struct kcm_sock *kcm;
 258
 259         WARN_ON(psock->ready_rx_msg);
 260
 261         if (psock->rx_kcm)
 262                 return psock->rx_kcm;
 263
 264         spin_lock_bh(&mux->rx_lock);
 265
 266         if (psock->rx_kcm) {
 267                 spin_unlock_bh(&mux->rx_lock);
 268                 return psock->rx_kcm;
 269         }
 270
 271         kcm_update_rx_mux_stats(mux, psock);
 272
 273         if (list_empty(&mux->kcm_rx_waiters)) {
 274                 psock->ready_rx_msg = head;
 275                 strp_pause(&psock->strp);
 276                 list_add_tail(&psock->psock_ready_list,
 277                               &mux->psocks_ready);
 278                 spin_unlock_bh(&mux->rx_lock);
 279                 return NULL;
 280         }
 281
 282         kcm = list_first_entry(&mux->kcm_rx_waiters,
 283                                struct kcm_sock, wait_rx_list);
 284         list_del(&kcm->wait_rx_list);
 285         kcm->rx_wait = false;
 286
 287         psock->rx_kcm = kcm;
 288         kcm->rx_psock = psock;
 289
 290         spin_unlock_bh(&mux->rx_lock);
 291
 292         return kcm;
 293 }
 294
 295 static void kcm_done(struct kcm_sock *kcm);
 296
 297 static void kcm_done_work(struct work_struct *w)
 298 {
 299         kcm_done(container_of(w, struct kcm_sock, done_work));
 300 }
 301
 302 /* Lower sock held */
 303 static void unreserve_rx_kcm(struct kcm_psock *psock,
 304                              bool rcv_ready)
 305 {
 306         struct kcm_sock *kcm = psock->rx_kcm;
 307         struct kcm_mux *mux = psock->mux;
 308
 309         if (!kcm)
 310                 return;
 311
 312         spin_lock_bh(&mux->rx_lock);
 313
 314         psock->rx_kcm = NULL;
 315         kcm->rx_psock = NULL;
 316
 317         /* Commit kcm->rx_psock before sk_rmem_alloc_get to sync with
 318          * kcm_rfree
 319          */
 320         smp_mb();
 321
 322         if (unlikely(kcm->done)) {
 323                 spin_unlock_bh(&mux->rx_lock);
 324
 325                 /* Need to run kcm_done in a task since we need to qcquire
 326                  * callback locks which may already be held here.
 327                  */
 328                 INIT_WORK(&kcm->done_work, kcm_done_work);
 329                 schedule_work(&kcm->done_work);
 330                 return;
 331         }
 332
 333         if (unlikely(kcm->rx_disabled)) {
 334                 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
 335         } else if (rcv_ready || unlikely(!sk_rmem_alloc_get(&kcm->sk))) {
 336                 /* Check for degenerative race with rx_wait that all
 337                  * data was dequeued (accounted for in kcm_rfree).
 338                  */
 339                 kcm_rcv_ready(kcm);
 340         }
 341         spin_unlock_bh(&mux->rx_lock);
 342 }
 343
 344 /* Lower sock lock held */
 345 static void psock_data_ready(struct sock *sk)
 346 {
 347         struct kcm_psock *psock;
 348
 349         read_lock_bh(&sk->sk_callback_lock);
 350
 351         psock = (struct kcm_psock *)sk->sk_user_data;
 352         if (likely(psock))
 353                 strp_data_ready(&psock->strp);
 354
 355         read_unlock_bh(&sk->sk_callback_lock);
 356 }
 357
 358 /* Called with lower sock held */
 359 static void kcm_rcv_strparser(struct strparser *strp, struct sk_buff *skb)
 360 {
 361         struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
 362         struct kcm_sock *kcm;
 363
 364 try_queue:
 365         kcm = reserve_rx_kcm(psock, skb);
 366         if (!kcm) {
 367                  /* Unable to reserve a KCM, message is held in psock and strp
 368                   * is paused.
 369                   */
 370                 return;
 371         }
 372
 373         if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
 374                 /* Should mean socket buffer full */
 375                 unreserve_rx_kcm(psock, false);
 376                 goto try_queue;
 377         }
 378 }
 379
 380 static int kcm_parse_func_strparser(struct strparser *strp, struct sk_buff *skb)
 381 {
 382         struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
 383         struct bpf_prog *prog = psock->bpf_prog;
 384
 385         return (*prog->bpf_func)(skb, prog->insnsi);
 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 POLLIN for a half close. Do a POLLHUP here
 400          * since application will normally not poll with POLLIN
 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(!frag->size)) {
 642                                 ret = -EINVAL;
 643                                 goto out;
 644                         }
 645
 646                         ret = kernel_sendpage(psock->sk->sk_socket,
 647                                               frag->page.p,
 648                                               frag->page_offset + frag_offset,
 649                                               frag->size - 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                                  * synchonization 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 < frag->size) {
 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)->tx_flags |= SKBTX_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)->tx_flags |= SKBTX_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_rx_msg *rxm;
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         rxm = strp_rx_msg(skb);
1136
1137         if (len > rxm->full_len)
1138                 len = rxm->full_len;
1139
1140         err = skb_copy_datagram_msg(skb, rxm->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 < rxm->full_len) {
1148                         if (sock->type == SOCK_DGRAM) {
1149                                 /* Truncated message */
1150                                 msg->msg_flags |= MSG_TRUNC;
1151                                 goto msg_finished;
1152                         }
1153                         rxm->offset += copied;
1154                         rxm->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_rx_msg *rxm;
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         rxm = strp_rx_msg(skb);
1196
1197         if (len > rxm->full_len)
1198                 len = rxm->full_len;
1199
1200         copied = skb_splice_bits(skb, sk, rxm->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         rxm->offset += copied;
1209         rxm->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                           char __user *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 (get_user(val, (int __user *)optval))
1282                 return -EINVAL;
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          * POLLHUP
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         struct strp_callbacks cb;
1380         int err;
1381
1382         csk = csock->sk;
1383         if (!csk)
1384                 return -EINVAL;
1385
1386         /* We must prevent loops or risk deadlock ! */
1387         if (csk->sk_family == PF_KCM)
1388                 return -EOPNOTSUPP;
1389
1390         psock = kmem_cache_zalloc(kcm_psockp, GFP_KERNEL);
1391         if (!psock)
1392                 return -ENOMEM;
1393
1394         psock->mux = mux;
1395         psock->sk = csk;
1396         psock->bpf_prog = prog;
1397
1398         cb.rcv_msg = kcm_rcv_strparser;
1399         cb.abort_parser = NULL;
1400         cb.parse_msg = kcm_parse_func_strparser;
1401         cb.read_sock_done = kcm_read_sock_done;
1402
1403         err = strp_init(&psock->strp, csk, &cb);
1404         if (err) {
1405                 kmem_cache_free(kcm_psockp, psock);
1406                 return err;
1407         }
1408
1409         sock_hold(csk);
1410
1411         write_lock_bh(&csk->sk_callback_lock);
1412         psock->save_data_ready = csk->sk_data_ready;
1413         psock->save_write_space = csk->sk_write_space;
1414         psock->save_state_change = csk->sk_state_change;
1415         csk->sk_user_data = psock;
1416         csk->sk_data_ready = psock_data_ready;
1417         csk->sk_write_space = psock_write_space;
1418         csk->sk_state_change = psock_state_change;
1419         write_unlock_bh(&csk->sk_callback_lock);
1420
1421         /* Finished initialization, now add the psock to the MUX. */
1422         spin_lock_bh(&mux->lock);
1423         head = &mux->psocks;
1424         list_for_each_entry(tpsock, &mux->psocks, psock_list) {
1425                 if (tpsock->index != index)
1426                         break;
1427                 head = &tpsock->psock_list;
1428                 index++;
1429         }
1430
1431         list_add(&psock->psock_list, head);
1432         psock->index = index;
1433
1434         KCM_STATS_INCR(mux->stats.psock_attach);
1435         mux->psocks_cnt++;
1436         psock_now_avail(psock);
1437         spin_unlock_bh(&mux->lock);
1438
1439         /* Schedule RX work in case there are already bytes queued */
1440         strp_check_rcv(&psock->strp);
1441
1442         return 0;
1443 }
1444
1445 static int kcm_attach_ioctl(struct socket *sock, struct kcm_attach *info)
1446 {
1447         struct socket *csock;
1448         struct bpf_prog *prog;
1449         int err;
1450
1451         csock = sockfd_lookup(info->fd, &err);
1452         if (!csock)
1453                 return -ENOENT;
1454
1455         prog = bpf_prog_get_type(info->bpf_fd, BPF_PROG_TYPE_SOCKET_FILTER);
1456         if (IS_ERR(prog)) {
1457                 err = PTR_ERR(prog);
1458                 goto out;
1459         }
1460
1461         err = kcm_attach(sock, csock, prog);
1462         if (err) {
1463                 bpf_prog_put(prog);
1464                 goto out;
1465         }
1466
1467         /* Keep reference on file also */
1468
1469         return 0;
1470 out:
1471         fput(csock->file);
1472         return err;
1473 }
1474
1475 static void kcm_unattach(struct kcm_psock *psock)
1476 {
1477         struct sock *csk = psock->sk;
1478         struct kcm_mux *mux = psock->mux;
1479
1480         lock_sock(csk);
1481
1482         /* Stop getting callbacks from TCP socket. After this there should
1483          * be no way to reserve a kcm for this psock.
1484          */
1485         write_lock_bh(&csk->sk_callback_lock);
1486         csk->sk_user_data = NULL;
1487         csk->sk_data_ready = psock->save_data_ready;
1488         csk->sk_write_space = psock->save_write_space;
1489         csk->sk_state_change = psock->save_state_change;
1490         strp_stop(&psock->strp);
1491
1492         if (WARN_ON(psock->rx_kcm)) {
1493                 write_unlock_bh(&csk->sk_callback_lock);
1494                 return;
1495         }
1496
1497         spin_lock_bh(&mux->rx_lock);
1498
1499         /* Stop receiver activities. After this point psock should not be
1500          * able to get onto ready list either through callbacks or work.
1501          */
1502         if (psock->ready_rx_msg) {
1503                 list_del(&psock->psock_ready_list);
1504                 kfree_skb(psock->ready_rx_msg);
1505                 psock->ready_rx_msg = NULL;
1506                 KCM_STATS_INCR(mux->stats.rx_ready_drops);
1507         }
1508
1509         spin_unlock_bh(&mux->rx_lock);
1510
1511         write_unlock_bh(&csk->sk_callback_lock);
1512
1513         /* Call strp_done without sock lock */
1514         release_sock(csk);
1515         strp_done(&psock->strp);
1516         lock_sock(csk);
1517
1518         bpf_prog_put(psock->bpf_prog);
1519
1520         spin_lock_bh(&mux->lock);
1521
1522         aggregate_psock_stats(&psock->stats, &mux->aggregate_psock_stats);
1523         save_strp_stats(&psock->strp, &mux->aggregate_strp_stats);
1524
1525         KCM_STATS_INCR(mux->stats.psock_unattach);
1526
1527         if (psock->tx_kcm) {
1528                 /* psock was reserved.  Just mark it finished and we will clean
1529                  * up in the kcm paths, we need kcm lock which can not be
1530                  * acquired here.
1531                  */
1532                 KCM_STATS_INCR(mux->stats.psock_unattach_rsvd);
1533                 spin_unlock_bh(&mux->lock);
1534
1535                 /* We are unattaching a socket that is reserved. Abort the
1536                  * socket since we may be out of sync in sending on it. We need
1537                  * to do this without the mux lock.
1538                  */
1539                 kcm_abort_tx_psock(psock, EPIPE, false);
1540
1541                 spin_lock_bh(&mux->lock);
1542                 if (!psock->tx_kcm) {
1543                         /* psock now unreserved in window mux was unlocked */
1544                         goto no_reserved;
1545                 }
1546                 psock->done = 1;
1547
1548                 /* Commit done before queuing work to process it */
1549                 smp_mb();
1550
1551                 /* Queue tx work to make sure psock->done is handled */
1552                 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
1553                 spin_unlock_bh(&mux->lock);
1554         } else {
1555 no_reserved:
1556                 if (!psock->tx_stopped)
1557                         list_del(&psock->psock_avail_list);
1558                 list_del(&psock->psock_list);
1559                 mux->psocks_cnt--;
1560                 spin_unlock_bh(&mux->lock);
1561
1562                 sock_put(csk);
1563                 fput(csk->sk_socket->file);
1564                 kmem_cache_free(kcm_psockp, psock);
1565         }
1566
1567         release_sock(csk);
1568 }
1569
1570 static int kcm_unattach_ioctl(struct socket *sock, struct kcm_unattach *info)
1571 {
1572         struct kcm_sock *kcm = kcm_sk(sock->sk);
1573         struct kcm_mux *mux = kcm->mux;
1574         struct kcm_psock *psock;
1575         struct socket *csock;
1576         struct sock *csk;
1577         int err;
1578
1579         csock = sockfd_lookup(info->fd, &err);
1580         if (!csock)
1581                 return -ENOENT;
1582
1583         csk = csock->sk;
1584         if (!csk) {
1585                 err = -EINVAL;
1586                 goto out;
1587         }
1588
1589         err = -ENOENT;
1590
1591         spin_lock_bh(&mux->lock);
1592
1593         list_for_each_entry(psock, &mux->psocks, psock_list) {
1594                 if (psock->sk != csk)
1595                         continue;
1596
1597                 /* Found the matching psock */
1598
1599                 if (psock->unattaching || WARN_ON(psock->done)) {
1600                         err = -EALREADY;
1601                         break;
1602                 }
1603
1604                 psock->unattaching = 1;
1605
1606                 spin_unlock_bh(&mux->lock);
1607
1608                 /* Lower socket lock should already be held */
1609                 kcm_unattach(psock);
1610
1611                 err = 0;
1612                 goto out;
1613         }
1614
1615         spin_unlock_bh(&mux->lock);
1616
1617 out:
1618         fput(csock->file);
1619         return err;
1620 }
1621
1622 static struct proto kcm_proto = {
1623         .name   = "KCM",
1624         .owner  = THIS_MODULE,
1625         .obj_size = sizeof(struct kcm_sock),
1626 };
1627
1628 /* Clone a kcm socket. */
1629 static int kcm_clone(struct socket *osock, struct kcm_clone *info,
1630                      struct socket **newsockp)
1631 {
1632         struct socket *newsock;
1633         struct sock *newsk;
1634         struct file *newfile;
1635         int err, newfd;
1636
1637         err = -ENFILE;
1638         newsock = sock_alloc();
1639         if (!newsock)
1640                 goto out;
1641
1642         newsock->type = osock->type;
1643         newsock->ops = osock->ops;
1644
1645         __module_get(newsock->ops->owner);
1646
1647         newfd = get_unused_fd_flags(0);
1648         if (unlikely(newfd < 0)) {
1649                 err = newfd;
1650                 goto out_fd_fail;
1651         }
1652
1653         newfile = sock_alloc_file(newsock, 0, osock->sk->sk_prot_creator->name);
1654         if (unlikely(IS_ERR(newfile))) {
1655                 err = PTR_ERR(newfile);
1656                 goto out_sock_alloc_fail;
1657         }
1658
1659         newsk = sk_alloc(sock_net(osock->sk), PF_KCM, GFP_KERNEL,
1660                          &kcm_proto, true);
1661         if (!newsk) {
1662                 err = -ENOMEM;
1663                 goto out_sk_alloc_fail;
1664         }
1665
1666         sock_init_data(newsock, newsk);
1667         init_kcm_sock(kcm_sk(newsk), kcm_sk(osock->sk)->mux);
1668
1669         fd_install(newfd, newfile);
1670         *newsockp = newsock;
1671         info->fd = newfd;
1672
1673         return 0;
1674
1675 out_sk_alloc_fail:
1676         fput(newfile);
1677 out_sock_alloc_fail:
1678         put_unused_fd(newfd);
1679 out_fd_fail:
1680         sock_release(newsock);
1681 out:
1682         return err;
1683 }
1684
1685 static int kcm_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
1686 {
1687         int err;
1688
1689         switch (cmd) {
1690         case SIOCKCMATTACH: {
1691                 struct kcm_attach info;
1692
1693                 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1694                         return -EFAULT;
1695
1696                 err = kcm_attach_ioctl(sock, &info);
1697
1698                 break;
1699         }
1700         case SIOCKCMUNATTACH: {
1701                 struct kcm_unattach info;
1702
1703                 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1704                         return -EFAULT;
1705
1706                 err = kcm_unattach_ioctl(sock, &info);
1707
1708                 break;
1709         }
1710         case SIOCKCMCLONE: {
1711                 struct kcm_clone info;
1712                 struct socket *newsock = NULL;
1713
1714                 err = kcm_clone(sock, &info, &newsock);
1715                 if (!err) {
1716                         if (copy_to_user((void __user *)arg, &info,
1717                                          sizeof(info))) {
1718                                 err = -EFAULT;
1719                                 sys_close(info.fd);
1720                         }
1721                 }
1722
1723                 break;
1724         }
1725         default:
1726                 err = -ENOIOCTLCMD;
1727                 break;
1728         }
1729
1730         return err;
1731 }
1732
1733 static void free_mux(struct rcu_head *rcu)
1734 {
1735         struct kcm_mux *mux = container_of(rcu,
1736             struct kcm_mux, rcu);
1737
1738         kmem_cache_free(kcm_muxp, mux);
1739 }
1740
1741 static void release_mux(struct kcm_mux *mux)
1742 {
1743         struct kcm_net *knet = mux->knet;
1744         struct kcm_psock *psock, *tmp_psock;
1745
1746         /* Release psocks */
1747         list_for_each_entry_safe(psock, tmp_psock,
1748                                  &mux->psocks, psock_list) {
1749                 if (!WARN_ON(psock->unattaching))
1750                         kcm_unattach(psock);
1751         }
1752
1753         if (WARN_ON(mux->psocks_cnt))
1754                 return;
1755
1756         __skb_queue_purge(&mux->rx_hold_queue);
1757
1758         mutex_lock(&knet->mutex);
1759         aggregate_mux_stats(&mux->stats, &knet->aggregate_mux_stats);
1760         aggregate_psock_stats(&mux->aggregate_psock_stats,
1761                               &knet->aggregate_psock_stats);
1762         aggregate_strp_stats(&mux->aggregate_strp_stats,
1763                              &knet->aggregate_strp_stats);
1764         list_del_rcu(&mux->kcm_mux_list);
1765         knet->count--;
1766         mutex_unlock(&knet->mutex);
1767
1768         call_rcu(&mux->rcu, free_mux);
1769 }
1770
1771 static void kcm_done(struct kcm_sock *kcm)
1772 {
1773         struct kcm_mux *mux = kcm->mux;
1774         struct sock *sk = &kcm->sk;
1775         int socks_cnt;
1776
1777         spin_lock_bh(&mux->rx_lock);
1778         if (kcm->rx_psock) {
1779                 /* Cleanup in unreserve_rx_kcm */
1780                 WARN_ON(kcm->done);
1781                 kcm->rx_disabled = 1;
1782                 kcm->done = 1;
1783                 spin_unlock_bh(&mux->rx_lock);
1784                 return;
1785         }
1786
1787         if (kcm->rx_wait) {
1788                 list_del(&kcm->wait_rx_list);
1789                 kcm->rx_wait = false;
1790         }
1791         /* Move any pending receive messages to other kcm sockets */
1792         requeue_rx_msgs(mux, &sk->sk_receive_queue);
1793
1794         spin_unlock_bh(&mux->rx_lock);
1795
1796         if (WARN_ON(sk_rmem_alloc_get(sk)))
1797                 return;
1798
1799         /* Detach from MUX */
1800         spin_lock_bh(&mux->lock);
1801
1802         list_del(&kcm->kcm_sock_list);
1803         mux->kcm_socks_cnt--;
1804         socks_cnt = mux->kcm_socks_cnt;
1805
1806         spin_unlock_bh(&mux->lock);
1807
1808         if (!socks_cnt) {
1809                 /* We are done with the mux now. */
1810                 release_mux(mux);
1811         }
1812
1813         WARN_ON(kcm->rx_wait);
1814
1815         sock_put(&kcm->sk);
1816 }
1817
1818 /* Called by kcm_release to close a KCM socket.
1819  * If this is the last KCM socket on the MUX, destroy the MUX.
1820  */
1821 static int kcm_release(struct socket *sock)
1822 {
1823         struct sock *sk = sock->sk;
1824         struct kcm_sock *kcm;
1825         struct kcm_mux *mux;
1826         struct kcm_psock *psock;
1827
1828         if (!sk)
1829                 return 0;
1830
1831         kcm = kcm_sk(sk);
1832         mux = kcm->mux;
1833
1834         sock_orphan(sk);
1835         kfree_skb(kcm->seq_skb);
1836
1837         lock_sock(sk);
1838         /* Purge queue under lock to avoid race condition with tx_work trying
1839          * to act when queue is nonempty. If tx_work runs after this point
1840          * it will just return.
1841          */
1842         __skb_queue_purge(&sk->sk_write_queue);
1843
1844         /* Set tx_stopped. This is checked when psock is bound to a kcm and we
1845          * get a writespace callback. This prevents further work being queued
1846          * from the callback (unbinding the psock occurs after canceling work.
1847          */
1848         kcm->tx_stopped = 1;
1849
1850         release_sock(sk);
1851
1852         spin_lock_bh(&mux->lock);
1853         if (kcm->tx_wait) {
1854                 /* Take of tx_wait list, after this point there should be no way
1855                  * that a psock will be assigned to this kcm.
1856                  */
1857                 list_del(&kcm->wait_psock_list);
1858                 kcm->tx_wait = false;
1859         }
1860         spin_unlock_bh(&mux->lock);
1861
1862         /* Cancel work. After this point there should be no outside references
1863          * to the kcm socket.
1864          */
1865         cancel_work_sync(&kcm->tx_work);
1866
1867         lock_sock(sk);
1868         psock = kcm->tx_psock;
1869         if (psock) {
1870                 /* A psock was reserved, so we need to kill it since it
1871                  * may already have some bytes queued from a message. We
1872                  * need to do this after removing kcm from tx_wait list.
1873                  */
1874                 kcm_abort_tx_psock(psock, EPIPE, false);
1875                 unreserve_psock(kcm);
1876         }
1877         release_sock(sk);
1878
1879         WARN_ON(kcm->tx_wait);
1880         WARN_ON(kcm->tx_psock);
1881
1882         sock->sk = NULL;
1883
1884         kcm_done(kcm);
1885
1886         return 0;
1887 }
1888
1889 static const struct proto_ops kcm_dgram_ops = {
1890         .family =       PF_KCM,
1891         .owner =        THIS_MODULE,
1892         .release =      kcm_release,
1893         .bind =         sock_no_bind,
1894         .connect =      sock_no_connect,
1895         .socketpair =   sock_no_socketpair,
1896         .accept =       sock_no_accept,
1897         .getname =      sock_no_getname,
1898         .poll =         datagram_poll,
1899         .ioctl =        kcm_ioctl,
1900         .listen =       sock_no_listen,
1901         .shutdown =     sock_no_shutdown,
1902         .setsockopt =   kcm_setsockopt,
1903         .getsockopt =   kcm_getsockopt,
1904         .sendmsg =      kcm_sendmsg,
1905         .recvmsg =      kcm_recvmsg,
1906         .mmap =         sock_no_mmap,
1907         .sendpage =     kcm_sendpage,
1908 };
1909
1910 static const struct proto_ops kcm_seqpacket_ops = {
1911         .family =       PF_KCM,
1912         .owner =        THIS_MODULE,
1913         .release =      kcm_release,
1914         .bind =         sock_no_bind,
1915         .connect =      sock_no_connect,
1916         .socketpair =   sock_no_socketpair,
1917         .accept =       sock_no_accept,
1918         .getname =      sock_no_getname,
1919         .poll =         datagram_poll,
1920         .ioctl =        kcm_ioctl,
1921         .listen =       sock_no_listen,
1922         .shutdown =     sock_no_shutdown,
1923         .setsockopt =   kcm_setsockopt,
1924         .getsockopt =   kcm_getsockopt,
1925         .sendmsg =      kcm_sendmsg,
1926         .recvmsg =      kcm_recvmsg,
1927         .mmap =         sock_no_mmap,
1928         .sendpage =     kcm_sendpage,
1929         .splice_read =  kcm_splice_read,
1930 };
1931
1932 /* Create proto operation for kcm sockets */
1933 static int kcm_create(struct net *net, struct socket *sock,
1934                       int protocol, int kern)
1935 {
1936         struct kcm_net *knet = net_generic(net, kcm_net_id);
1937         struct sock *sk;
1938         struct kcm_mux *mux;
1939
1940         switch (sock->type) {
1941         case SOCK_DGRAM:
1942                 sock->ops = &kcm_dgram_ops;
1943                 break;
1944         case SOCK_SEQPACKET:
1945                 sock->ops = &kcm_seqpacket_ops;
1946                 break;
1947         default:
1948                 return -ESOCKTNOSUPPORT;
1949         }
1950
1951         if (protocol != KCMPROTO_CONNECTED)
1952                 return -EPROTONOSUPPORT;
1953
1954         sk = sk_alloc(net, PF_KCM, GFP_KERNEL, &kcm_proto, kern);
1955         if (!sk)
1956                 return -ENOMEM;
1957
1958         /* Allocate a kcm mux, shared between KCM sockets */
1959         mux = kmem_cache_zalloc(kcm_muxp, GFP_KERNEL);
1960         if (!mux) {
1961                 sk_free(sk);
1962                 return -ENOMEM;
1963         }
1964
1965         spin_lock_init(&mux->lock);
1966         spin_lock_init(&mux->rx_lock);
1967         INIT_LIST_HEAD(&mux->kcm_socks);
1968         INIT_LIST_HEAD(&mux->kcm_rx_waiters);
1969         INIT_LIST_HEAD(&mux->kcm_tx_waiters);
1970
1971         INIT_LIST_HEAD(&mux->psocks);
1972         INIT_LIST_HEAD(&mux->psocks_ready);
1973         INIT_LIST_HEAD(&mux->psocks_avail);
1974
1975         mux->knet = knet;
1976
1977         /* Add new MUX to list */
1978         mutex_lock(&knet->mutex);
1979         list_add_rcu(&mux->kcm_mux_list, &knet->mux_list);
1980         knet->count++;
1981         mutex_unlock(&knet->mutex);
1982
1983         skb_queue_head_init(&mux->rx_hold_queue);
1984
1985         /* Init KCM socket */
1986         sock_init_data(sock, sk);
1987         init_kcm_sock(kcm_sk(sk), mux);
1988
1989         return 0;
1990 }
1991
1992 static const struct net_proto_family kcm_family_ops = {
1993         .family = PF_KCM,
1994         .create = kcm_create,
1995         .owner  = THIS_MODULE,
1996 };
1997
1998 static __net_init int kcm_init_net(struct net *net)
1999 {
2000         struct kcm_net *knet = net_generic(net, kcm_net_id);
2001
2002         INIT_LIST_HEAD_RCU(&knet->mux_list);
2003         mutex_init(&knet->mutex);
2004
2005         return 0;
2006 }
2007
2008 static __net_exit void kcm_exit_net(struct net *net)
2009 {
2010         struct kcm_net *knet = net_generic(net, kcm_net_id);
2011
2012         /* All KCM sockets should be closed at this point, which should mean
2013          * that all multiplexors and psocks have been destroyed.
2014          */
2015         WARN_ON(!list_empty(&knet->mux_list));
2016 }
2017
2018 static struct pernet_operations kcm_net_ops = {
2019         .init = kcm_init_net,
2020         .exit = kcm_exit_net,
2021         .id   = &kcm_net_id,
2022         .size = sizeof(struct kcm_net),
2023 };
2024
2025 static int __init kcm_init(void)
2026 {
2027         int err = -ENOMEM;
2028
2029         kcm_muxp = kmem_cache_create("kcm_mux_cache",
2030                                      sizeof(struct kcm_mux), 0,
2031                                      SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
2032         if (!kcm_muxp)
2033                 goto fail;
2034
2035         kcm_psockp = kmem_cache_create("kcm_psock_cache",
2036                                        sizeof(struct kcm_psock), 0,
2037                                         SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
2038         if (!kcm_psockp)
2039                 goto fail;
2040
2041         kcm_wq = create_singlethread_workqueue("kkcmd");
2042         if (!kcm_wq)
2043                 goto fail;
2044
2045         err = proto_register(&kcm_proto, 1);
2046         if (err)
2047                 goto fail;
2048
2049         err = sock_register(&kcm_family_ops);
2050         if (err)
2051                 goto sock_register_fail;
2052
2053         err = register_pernet_device(&kcm_net_ops);
2054         if (err)
2055                 goto net_ops_fail;
2056
2057         err = kcm_proc_init();
2058         if (err)
2059                 goto proc_init_fail;
2060
2061         return 0;
2062
2063 proc_init_fail:
2064         unregister_pernet_device(&kcm_net_ops);
2065
2066 net_ops_fail:
2067         sock_unregister(PF_KCM);
2068
2069 sock_register_fail:
2070         proto_unregister(&kcm_proto);
2071
2072 fail:
2073         kmem_cache_destroy(kcm_muxp);
2074         kmem_cache_destroy(kcm_psockp);
2075
2076         if (kcm_wq)
2077                 destroy_workqueue(kcm_wq);
2078
2079         return err;
2080 }
2081
2082 static void __exit kcm_exit(void)
2083 {
2084         kcm_proc_exit();
2085         unregister_pernet_device(&kcm_net_ops);
2086         sock_unregister(PF_KCM);
2087         proto_unregister(&kcm_proto);
2088         destroy_workqueue(kcm_wq);
2089
2090         kmem_cache_destroy(kcm_muxp);
2091         kmem_cache_destroy(kcm_psockp);
2092 }
2093
2094 module_init(kcm_init);
2095 module_exit(kcm_exit);
2096
2097 MODULE_LICENSE("GPL");
2098 MODULE_ALIAS_NETPROTO(PF_KCM);
2099