net/kcm/kcmsock.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Kernel Connection Multiplexor
   4  *
   5  * Copyright (c) 2016 Tom Herbert <[email protected]>
   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 #include <trace/events/sock.h>
  32
  33 unsigned int kcm_net_id;
  34
  35 static struct kmem_cache *kcm_psockp __read_mostly;
  36 static struct kmem_cache *kcm_muxp __read_mostly;
  37 static struct workqueue_struct *kcm_wq;
  38
  39 static inline struct kcm_sock *kcm_sk(const struct sock *sk)
  40 {
  41         return (struct kcm_sock *)sk;
  42 }
  43
  44 static inline struct kcm_tx_msg *kcm_tx_msg(struct sk_buff *skb)
  45 {
  46         return (struct kcm_tx_msg *)skb->cb;
  47 }
  48
  49 static void report_csk_error(struct sock *csk, int err)
  50 {
  51         csk->sk_err = EPIPE;
  52         sk_error_report(csk);
  53 }
  54
  55 static void kcm_abort_tx_psock(struct kcm_psock *psock, int err,
  56                                bool wakeup_kcm)
  57 {
  58         struct sock *csk = psock->sk;
  59         struct kcm_mux *mux = psock->mux;
  60
  61         /* Unrecoverable error in transmit */
  62
  63         spin_lock_bh(&mux->lock);
  64
  65         if (psock->tx_stopped) {
  66                 spin_unlock_bh(&mux->lock);
  67                 return;
  68         }
  69
  70         psock->tx_stopped = 1;
  71         KCM_STATS_INCR(psock->stats.tx_aborts);
  72
  73         if (!psock->tx_kcm) {
  74                 /* Take off psocks_avail list */
  75                 list_del(&psock->psock_avail_list);
  76         } else if (wakeup_kcm) {
  77                 /* In this case psock is being aborted while outside of
  78                  * write_msgs and psock is reserved. Schedule tx_work
  79                  * to handle the failure there. Need to commit tx_stopped
  80                  * before queuing work.
  81                  */
  82                 smp_mb();
  83
  84                 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
  85         }
  86
  87         spin_unlock_bh(&mux->lock);
  88
  89         /* Report error on lower socket */
  90         report_csk_error(csk, err);
  91 }
  92
  93 /* RX mux lock held. */
  94 static void kcm_update_rx_mux_stats(struct kcm_mux *mux,
  95                                     struct kcm_psock *psock)
  96 {
  97         STRP_STATS_ADD(mux->stats.rx_bytes,
  98                        psock->strp.stats.bytes -
  99                        psock->saved_rx_bytes);
 100         mux->stats.rx_msgs +=
 101                 psock->strp.stats.msgs - psock->saved_rx_msgs;
 102         psock->saved_rx_msgs = psock->strp.stats.msgs;
 103         psock->saved_rx_bytes = psock->strp.stats.bytes;
 104 }
 105
 106 static void kcm_update_tx_mux_stats(struct kcm_mux *mux,
 107                                     struct kcm_psock *psock)
 108 {
 109         KCM_STATS_ADD(mux->stats.tx_bytes,
 110                       psock->stats.tx_bytes - psock->saved_tx_bytes);
 111         mux->stats.tx_msgs +=
 112                 psock->stats.tx_msgs - psock->saved_tx_msgs;
 113         psock->saved_tx_msgs = psock->stats.tx_msgs;
 114         psock->saved_tx_bytes = psock->stats.tx_bytes;
 115 }
 116
 117 static int kcm_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
 118
 119 /* KCM is ready to receive messages on its queue-- either the KCM is new or
 120  * has become unblocked after being blocked on full socket buffer. Queue any
 121  * pending ready messages on a psock. RX mux lock held.
 122  */
 123 static void kcm_rcv_ready(struct kcm_sock *kcm)
 124 {
 125         struct kcm_mux *mux = kcm->mux;
 126         struct kcm_psock *psock;
 127         struct sk_buff *skb;
 128
 129         if (unlikely(kcm->rx_wait || kcm->rx_psock || kcm->rx_disabled))
 130                 return;
 131
 132         while (unlikely((skb = __skb_dequeue(&mux->rx_hold_queue)))) {
 133                 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
 134                         /* Assuming buffer limit has been reached */
 135                         skb_queue_head(&mux->rx_hold_queue, skb);
 136                         WARN_ON(!sk_rmem_alloc_get(&kcm->sk));
 137                         return;
 138                 }
 139         }
 140
 141         while (!list_empty(&mux->psocks_ready)) {
 142                 psock = list_first_entry(&mux->psocks_ready, struct kcm_psock,
 143                                          psock_ready_list);
 144
 145                 if (kcm_queue_rcv_skb(&kcm->sk, psock->ready_rx_msg)) {
 146                         /* Assuming buffer limit has been reached */
 147                         WARN_ON(!sk_rmem_alloc_get(&kcm->sk));
 148                         return;
 149                 }
 150
 151                 /* Consumed the ready message on the psock. Schedule rx_work to
 152                  * get more messages.
 153                  */
 154                 list_del(&psock->psock_ready_list);
 155                 psock->ready_rx_msg = NULL;
 156                 /* Commit clearing of ready_rx_msg for queuing work */
 157                 smp_mb();
 158
 159                 strp_unpause(&psock->strp);
 160                 strp_check_rcv(&psock->strp);
 161         }
 162
 163         /* Buffer limit is okay now, add to ready list */
 164         list_add_tail(&kcm->wait_rx_list,
 165                       &kcm->mux->kcm_rx_waiters);
 166         /* paired with lockless reads in kcm_rfree() */
 167         WRITE_ONCE(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 (!READ_ONCE(kcm->rx_wait) && !READ_ONCE(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                         /* paired with lockless reads in kcm_rfree() */
 243                         WRITE_ONCE(kcm->rx_wait, false);
 244
 245                         /* Commit rx_wait to read in kcm_free */
 246                         smp_wmb();
 247
 248                         goto try_again;
 249                 }
 250         }
 251 }
 252
 253 /* Lower sock lock held */
 254 static struct kcm_sock *reserve_rx_kcm(struct kcm_psock *psock,
 255                                        struct sk_buff *head)
 256 {
 257         struct kcm_mux *mux = psock->mux;
 258         struct kcm_sock *kcm;
 259
 260         WARN_ON(psock->ready_rx_msg);
 261
 262         if (psock->rx_kcm)
 263                 return psock->rx_kcm;
 264
 265         spin_lock_bh(&mux->rx_lock);
 266
 267         if (psock->rx_kcm) {
 268                 spin_unlock_bh(&mux->rx_lock);
 269                 return psock->rx_kcm;
 270         }
 271
 272         kcm_update_rx_mux_stats(mux, psock);
 273
 274         if (list_empty(&mux->kcm_rx_waiters)) {
 275                 psock->ready_rx_msg = head;
 276                 strp_pause(&psock->strp);
 277                 list_add_tail(&psock->psock_ready_list,
 278                               &mux->psocks_ready);
 279                 spin_unlock_bh(&mux->rx_lock);
 280                 return NULL;
 281         }
 282
 283         kcm = list_first_entry(&mux->kcm_rx_waiters,
 284                                struct kcm_sock, wait_rx_list);
 285         list_del(&kcm->wait_rx_list);
 286         /* paired with lockless reads in kcm_rfree() */
 287         WRITE_ONCE(kcm->rx_wait, false);
 288
 289         psock->rx_kcm = kcm;
 290         /* paired with lockless reads in kcm_rfree() */
 291         WRITE_ONCE(kcm->rx_psock, psock);
 292
 293         spin_unlock_bh(&mux->rx_lock);
 294
 295         return kcm;
 296 }
 297
 298 static void kcm_done(struct kcm_sock *kcm);
 299
 300 static void kcm_done_work(struct work_struct *w)
 301 {
 302         kcm_done(container_of(w, struct kcm_sock, done_work));
 303 }
 304
 305 /* Lower sock held */
 306 static void unreserve_rx_kcm(struct kcm_psock *psock,
 307                              bool rcv_ready)
 308 {
 309         struct kcm_sock *kcm = psock->rx_kcm;
 310         struct kcm_mux *mux = psock->mux;
 311
 312         if (!kcm)
 313                 return;
 314
 315         spin_lock_bh(&mux->rx_lock);
 316
 317         psock->rx_kcm = NULL;
 318         /* paired with lockless reads in kcm_rfree() */
 319         WRITE_ONCE(kcm->rx_psock, NULL);
 320
 321         /* Commit kcm->rx_psock before sk_rmem_alloc_get to sync with
 322          * kcm_rfree
 323          */
 324         smp_mb();
 325
 326         if (unlikely(kcm->done)) {
 327                 spin_unlock_bh(&mux->rx_lock);
 328
 329                 /* Need to run kcm_done in a task since we need to qcquire
 330                  * callback locks which may already be held here.
 331                  */
 332                 INIT_WORK(&kcm->done_work, kcm_done_work);
 333                 schedule_work(&kcm->done_work);
 334                 return;
 335         }
 336
 337         if (unlikely(kcm->rx_disabled)) {
 338                 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
 339         } else if (rcv_ready || unlikely(!sk_rmem_alloc_get(&kcm->sk))) {
 340                 /* Check for degenerative race with rx_wait that all
 341                  * data was dequeued (accounted for in kcm_rfree).
 342                  */
 343                 kcm_rcv_ready(kcm);
 344         }
 345         spin_unlock_bh(&mux->rx_lock);
 346 }
 347
 348 /* Lower sock lock held */
 349 static void psock_data_ready(struct sock *sk)
 350 {
 351         struct kcm_psock *psock;
 352
 353         trace_sk_data_ready(sk);
 354
 355         read_lock_bh(&sk->sk_callback_lock);
 356
 357         psock = (struct kcm_psock *)sk->sk_user_data;
 358         if (likely(psock))
 359                 strp_data_ready(&psock->strp);
 360
 361         read_unlock_bh(&sk->sk_callback_lock);
 362 }
 363
 364 /* Called with lower sock held */
 365 static void kcm_rcv_strparser(struct strparser *strp, struct sk_buff *skb)
 366 {
 367         struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
 368         struct kcm_sock *kcm;
 369
 370 try_queue:
 371         kcm = reserve_rx_kcm(psock, skb);
 372         if (!kcm) {
 373                  /* Unable to reserve a KCM, message is held in psock and strp
 374                   * is paused.
 375                   */
 376                 return;
 377         }
 378
 379         if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
 380                 /* Should mean socket buffer full */
 381                 unreserve_rx_kcm(psock, false);
 382                 goto try_queue;
 383         }
 384 }
 385
 386 static int kcm_parse_func_strparser(struct strparser *strp, struct sk_buff *skb)
 387 {
 388         struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
 389         struct bpf_prog *prog = psock->bpf_prog;
 390         int res;
 391
 392         res = bpf_prog_run_pin_on_cpu(prog, skb);
 393         return res;
 394 }
 395
 396 static int kcm_read_sock_done(struct strparser *strp, int err)
 397 {
 398         struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
 399
 400         unreserve_rx_kcm(psock, true);
 401
 402         return err;
 403 }
 404
 405 static void psock_state_change(struct sock *sk)
 406 {
 407         /* TCP only does a EPOLLIN for a half close. Do a EPOLLHUP here
 408          * since application will normally not poll with EPOLLIN
 409          * on the TCP sockets.
 410          */
 411
 412         report_csk_error(sk, EPIPE);
 413 }
 414
 415 static void psock_write_space(struct sock *sk)
 416 {
 417         struct kcm_psock *psock;
 418         struct kcm_mux *mux;
 419         struct kcm_sock *kcm;
 420
 421         read_lock_bh(&sk->sk_callback_lock);
 422
 423         psock = (struct kcm_psock *)sk->sk_user_data;
 424         if (unlikely(!psock))
 425                 goto out;
 426         mux = psock->mux;
 427
 428         spin_lock_bh(&mux->lock);
 429
 430         /* Check if the socket is reserved so someone is waiting for sending. */
 431         kcm = psock->tx_kcm;
 432         if (kcm && !unlikely(kcm->tx_stopped))
 433                 queue_work(kcm_wq, &kcm->tx_work);
 434
 435         spin_unlock_bh(&mux->lock);
 436 out:
 437         read_unlock_bh(&sk->sk_callback_lock);
 438 }
 439
 440 static void unreserve_psock(struct kcm_sock *kcm);
 441
 442 /* kcm sock is locked. */
 443 static struct kcm_psock *reserve_psock(struct kcm_sock *kcm)
 444 {
 445         struct kcm_mux *mux = kcm->mux;
 446         struct kcm_psock *psock;
 447
 448         psock = kcm->tx_psock;
 449
 450         smp_rmb(); /* Must read tx_psock before tx_wait */
 451
 452         if (psock) {
 453                 WARN_ON(kcm->tx_wait);
 454                 if (unlikely(psock->tx_stopped))
 455                         unreserve_psock(kcm);
 456                 else
 457                         return kcm->tx_psock;
 458         }
 459
 460         spin_lock_bh(&mux->lock);
 461
 462         /* Check again under lock to see if psock was reserved for this
 463          * psock via psock_unreserve.
 464          */
 465         psock = kcm->tx_psock;
 466         if (unlikely(psock)) {
 467                 WARN_ON(kcm->tx_wait);
 468                 spin_unlock_bh(&mux->lock);
 469                 return kcm->tx_psock;
 470         }
 471
 472         if (!list_empty(&mux->psocks_avail)) {
 473                 psock = list_first_entry(&mux->psocks_avail,
 474                                          struct kcm_psock,
 475                                          psock_avail_list);
 476                 list_del(&psock->psock_avail_list);
 477                 if (kcm->tx_wait) {
 478                         list_del(&kcm->wait_psock_list);
 479                         kcm->tx_wait = false;
 480                 }
 481                 kcm->tx_psock = psock;
 482                 psock->tx_kcm = kcm;
 483                 KCM_STATS_INCR(psock->stats.reserved);
 484         } else if (!kcm->tx_wait) {
 485                 list_add_tail(&kcm->wait_psock_list,
 486                               &mux->kcm_tx_waiters);
 487                 kcm->tx_wait = true;
 488         }
 489
 490         spin_unlock_bh(&mux->lock);
 491
 492         return psock;
 493 }
 494
 495 /* mux lock held */
 496 static void psock_now_avail(struct kcm_psock *psock)
 497 {
 498         struct kcm_mux *mux = psock->mux;
 499         struct kcm_sock *kcm;
 500
 501         if (list_empty(&mux->kcm_tx_waiters)) {
 502                 list_add_tail(&psock->psock_avail_list,
 503                               &mux->psocks_avail);
 504         } else {
 505                 kcm = list_first_entry(&mux->kcm_tx_waiters,
 506                                        struct kcm_sock,
 507                                        wait_psock_list);
 508                 list_del(&kcm->wait_psock_list);
 509                 kcm->tx_wait = false;
 510                 psock->tx_kcm = kcm;
 511
 512                 /* Commit before changing tx_psock since that is read in
 513                  * reserve_psock before queuing work.
 514                  */
 515                 smp_mb();
 516
 517                 kcm->tx_psock = psock;
 518                 KCM_STATS_INCR(psock->stats.reserved);
 519                 queue_work(kcm_wq, &kcm->tx_work);
 520         }
 521 }
 522
 523 /* kcm sock is locked. */
 524 static void unreserve_psock(struct kcm_sock *kcm)
 525 {
 526         struct kcm_psock *psock;
 527         struct kcm_mux *mux = kcm->mux;
 528
 529         spin_lock_bh(&mux->lock);
 530
 531         psock = kcm->tx_psock;
 532
 533         if (WARN_ON(!psock)) {
 534                 spin_unlock_bh(&mux->lock);
 535                 return;
 536         }
 537
 538         smp_rmb(); /* Read tx_psock before tx_wait */
 539
 540         kcm_update_tx_mux_stats(mux, psock);
 541
 542         WARN_ON(kcm->tx_wait);
 543
 544         kcm->tx_psock = NULL;
 545         psock->tx_kcm = NULL;
 546         KCM_STATS_INCR(psock->stats.unreserved);
 547
 548         if (unlikely(psock->tx_stopped)) {
 549                 if (psock->done) {
 550                         /* Deferred free */
 551                         list_del(&psock->psock_list);
 552                         mux->psocks_cnt--;
 553                         sock_put(psock->sk);
 554                         fput(psock->sk->sk_socket->file);
 555                         kmem_cache_free(kcm_psockp, psock);
 556                 }
 557
 558                 /* Don't put back on available list */
 559
 560                 spin_unlock_bh(&mux->lock);
 561
 562                 return;
 563         }
 564
 565         psock_now_avail(psock);
 566
 567         spin_unlock_bh(&mux->lock);
 568 }
 569
 570 static void kcm_report_tx_retry(struct kcm_sock *kcm)
 571 {
 572         struct kcm_mux *mux = kcm->mux;
 573
 574         spin_lock_bh(&mux->lock);
 575         KCM_STATS_INCR(mux->stats.tx_retries);
 576         spin_unlock_bh(&mux->lock);
 577 }
 578
 579 /* Write any messages ready on the kcm socket.  Called with kcm sock lock
 580  * held.  Return bytes actually sent or error.
 581  */
 582 static int kcm_write_msgs(struct kcm_sock *kcm)
 583 {
 584         unsigned int total_sent = 0;
 585         struct sock *sk = &kcm->sk;
 586         struct kcm_psock *psock;
 587         struct sk_buff *head;
 588         int ret = 0;
 589
 590         kcm->tx_wait_more = false;
 591         psock = kcm->tx_psock;
 592         if (unlikely(psock && psock->tx_stopped)) {
 593                 /* A reserved psock was aborted asynchronously. Unreserve
 594                  * it and we'll retry the message.
 595                  */
 596                 unreserve_psock(kcm);
 597                 kcm_report_tx_retry(kcm);
 598                 if (skb_queue_empty(&sk->sk_write_queue))
 599                         return 0;
 600
 601                 kcm_tx_msg(skb_peek(&sk->sk_write_queue))->started_tx = false;
 602         }
 603
 604 retry:
 605         while ((head = skb_peek(&sk->sk_write_queue))) {
 606                 struct msghdr msg = {
 607                         .msg_flags = MSG_DONTWAIT | MSG_SPLICE_PAGES,
 608                 };
 609                 struct kcm_tx_msg *txm = kcm_tx_msg(head);
 610                 struct sk_buff *skb;
 611                 unsigned int msize;
 612                 int i;
 613
 614                 if (!txm->started_tx) {
 615                         psock = reserve_psock(kcm);
 616                         if (!psock)
 617                                 goto out;
 618                         skb = head;
 619                         txm->frag_offset = 0;
 620                         txm->sent = 0;
 621                         txm->started_tx = true;
 622                 } else {
 623                         if (WARN_ON(!psock)) {
 624                                 ret = -EINVAL;
 625                                 goto out;
 626                         }
 627                         skb = txm->frag_skb;
 628                 }
 629
 630                 if (WARN_ON(!skb_shinfo(skb)->nr_frags)) {
 631                         ret = -EINVAL;
 632                         goto out;
 633                 }
 634
 635                 msize = 0;
 636                 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
 637                         msize += skb_shinfo(skb)->frags[i].bv_len;
 638
 639                 iov_iter_bvec(&msg.msg_iter, ITER_SOURCE,
 640                               skb_shinfo(skb)->frags, skb_shinfo(skb)->nr_frags,
 641                               msize);
 642                 iov_iter_advance(&msg.msg_iter, txm->frag_offset);
 643
 644                 do {
 645                         ret = sock_sendmsg(psock->sk->sk_socket, &msg);
 646                         if (ret <= 0) {
 647                                 if (ret == -EAGAIN) {
 648                                         /* Save state to try again when there's
 649                                          * write space on the socket
 650                                          */
 651                                         txm->frag_skb = skb;
 652                                         ret = 0;
 653                                         goto out;
 654                                 }
 655
 656                                 /* Hard failure in sending message, abort this
 657                                  * psock since it has lost framing
 658                                  * synchronization and retry sending the
 659                                  * message from the beginning.
 660                                  */
 661                                 kcm_abort_tx_psock(psock, ret ? -ret : EPIPE,
 662                                                    true);
 663                                 unreserve_psock(kcm);
 664                                 psock = NULL;
 665
 666                                 txm->started_tx = false;
 667                                 kcm_report_tx_retry(kcm);
 668                                 ret = 0;
 669                                 goto retry;
 670                         }
 671
 672                         txm->sent += ret;
 673                         txm->frag_offset += ret;
 674                         KCM_STATS_ADD(psock->stats.tx_bytes, ret);
 675                 } while (msg.msg_iter.count > 0);
 676
 677                 if (skb == head) {
 678                         if (skb_has_frag_list(skb)) {
 679                                 txm->frag_skb = skb_shinfo(skb)->frag_list;
 680                                 txm->frag_offset = 0;
 681                                 continue;
 682                         }
 683                 } else if (skb->next) {
 684                         txm->frag_skb = skb->next;
 685                         txm->frag_offset = 0;
 686                         continue;
 687                 }
 688
 689                 /* Successfully sent the whole packet, account for it. */
 690                 sk->sk_wmem_queued -= txm->sent;
 691                 total_sent += txm->sent;
 692                 skb_dequeue(&sk->sk_write_queue);
 693                 kfree_skb(head);
 694                 KCM_STATS_INCR(psock->stats.tx_msgs);
 695         }
 696 out:
 697         if (!head) {
 698                 /* Done with all queued messages. */
 699                 WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
 700                 if (psock)
 701                         unreserve_psock(kcm);
 702         }
 703
 704         /* Check if write space is available */
 705         sk->sk_write_space(sk);
 706
 707         return total_sent ? : ret;
 708 }
 709
 710 static void kcm_tx_work(struct work_struct *w)
 711 {
 712         struct kcm_sock *kcm = container_of(w, struct kcm_sock, tx_work);
 713         struct sock *sk = &kcm->sk;
 714         int err;
 715
 716         lock_sock(sk);
 717
 718         /* Primarily for SOCK_DGRAM sockets, also handle asynchronous tx
 719          * aborts
 720          */
 721         err = kcm_write_msgs(kcm);
 722         if (err < 0) {
 723                 /* Hard failure in write, report error on KCM socket */
 724                 pr_warn("KCM: Hard failure on kcm_write_msgs %d\n", err);
 725                 report_csk_error(&kcm->sk, -err);
 726                 goto out;
 727         }
 728
 729         /* Primarily for SOCK_SEQPACKET sockets */
 730         if (likely(sk->sk_socket) &&
 731             test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
 732                 clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 733                 sk->sk_write_space(sk);
 734         }
 735
 736 out:
 737         release_sock(sk);
 738 }
 739
 740 static void kcm_push(struct kcm_sock *kcm)
 741 {
 742         if (kcm->tx_wait_more)
 743                 kcm_write_msgs(kcm);
 744 }
 745
 746 static int kcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 747 {
 748         struct sock *sk = sock->sk;
 749         struct kcm_sock *kcm = kcm_sk(sk);
 750         struct sk_buff *skb = NULL, *head = NULL;
 751         size_t copy, copied = 0;
 752         long timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
 753         int eor = (sock->type == SOCK_DGRAM) ?
 754                   !(msg->msg_flags & MSG_MORE) : !!(msg->msg_flags & MSG_EOR);
 755         int err = -EPIPE;
 756
 757         lock_sock(sk);
 758
 759         /* Per tcp_sendmsg this should be in poll */
 760         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 761
 762         if (sk->sk_err)
 763                 goto out_error;
 764
 765         if (kcm->seq_skb) {
 766                 /* Previously opened message */
 767                 head = kcm->seq_skb;
 768                 skb = kcm_tx_msg(head)->last_skb;
 769                 goto start;
 770         }
 771
 772         /* Call the sk_stream functions to manage the sndbuf mem. */
 773         if (!sk_stream_memory_free(sk)) {
 774                 kcm_push(kcm);
 775                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 776                 err = sk_stream_wait_memory(sk, &timeo);
 777                 if (err)
 778                         goto out_error;
 779         }
 780
 781         if (msg_data_left(msg)) {
 782                 /* New message, alloc head skb */
 783                 head = alloc_skb(0, sk->sk_allocation);
 784                 while (!head) {
 785                         kcm_push(kcm);
 786                         err = sk_stream_wait_memory(sk, &timeo);
 787                         if (err)
 788                                 goto out_error;
 789
 790                         head = alloc_skb(0, sk->sk_allocation);
 791                 }
 792
 793                 skb = head;
 794
 795                 /* Set ip_summed to CHECKSUM_UNNECESSARY to avoid calling
 796                  * csum_and_copy_from_iter from skb_do_copy_data_nocache.
 797                  */
 798                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 799         }
 800
 801 start:
 802         while (msg_data_left(msg)) {
 803                 bool merge = true;
 804                 int i = skb_shinfo(skb)->nr_frags;
 805                 struct page_frag *pfrag = sk_page_frag(sk);
 806
 807                 if (!sk_page_frag_refill(sk, pfrag))
 808                         goto wait_for_memory;
 809
 810                 if (!skb_can_coalesce(skb, i, pfrag->page,
 811                                       pfrag->offset)) {
 812                         if (i == MAX_SKB_FRAGS) {
 813                                 struct sk_buff *tskb;
 814
 815                                 tskb = alloc_skb(0, sk->sk_allocation);
 816                                 if (!tskb)
 817                                         goto wait_for_memory;
 818
 819                                 if (head == skb)
 820                                         skb_shinfo(head)->frag_list = tskb;
 821                                 else
 822                                         skb->next = tskb;
 823
 824                                 skb = tskb;
 825                                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 826                                 continue;
 827                         }
 828                         merge = false;
 829                 }
 830
 831                 if (msg->msg_flags & MSG_SPLICE_PAGES) {
 832                         copy = msg_data_left(msg);
 833                         if (!sk_wmem_schedule(sk, copy))
 834                                 goto wait_for_memory;
 835
 836                         err = skb_splice_from_iter(skb, &msg->msg_iter, copy,
 837                                                    sk->sk_allocation);
 838                         if (err < 0) {
 839                                 if (err == -EMSGSIZE)
 840                                         goto wait_for_memory;
 841                                 goto out_error;
 842                         }
 843
 844                         copy = err;
 845                         skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
 846                         sk_wmem_queued_add(sk, copy);
 847                         sk_mem_charge(sk, copy);
 848
 849                         if (head != skb)
 850                                 head->truesize += copy;
 851                 } else {
 852                         copy = min_t(int, msg_data_left(msg),
 853                                      pfrag->size - pfrag->offset);
 854                         if (!sk_wmem_schedule(sk, copy))
 855                                 goto wait_for_memory;
 856
 857                         err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
 858                                                        pfrag->page,
 859                                                        pfrag->offset,
 860                                                        copy);
 861                         if (err)
 862                                 goto out_error;
 863
 864                         /* Update the skb. */
 865                         if (merge) {
 866                                 skb_frag_size_add(
 867                                         &skb_shinfo(skb)->frags[i - 1], copy);
 868                         } else {
 869                                 skb_fill_page_desc(skb, i, pfrag->page,
 870                                                    pfrag->offset, copy);
 871                                 get_page(pfrag->page);
 872                         }
 873
 874                         pfrag->offset += copy;
 875                 }
 876
 877                 copied += copy;
 878                 if (head != skb) {
 879                         head->len += copy;
 880                         head->data_len += copy;
 881                 }
 882
 883                 continue;
 884
 885 wait_for_memory:
 886                 kcm_push(kcm);
 887                 err = sk_stream_wait_memory(sk, &timeo);
 888                 if (err)
 889                         goto out_error;
 890         }
 891
 892         if (eor) {
 893                 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
 894
 895                 if (head) {
 896                         /* Message complete, queue it on send buffer */
 897                         __skb_queue_tail(&sk->sk_write_queue, head);
 898                         kcm->seq_skb = NULL;
 899                         KCM_STATS_INCR(kcm->stats.tx_msgs);
 900                 }
 901
 902                 if (msg->msg_flags & MSG_BATCH) {
 903                         kcm->tx_wait_more = true;
 904                 } else if (kcm->tx_wait_more || not_busy) {
 905                         err = kcm_write_msgs(kcm);
 906                         if (err < 0) {
 907                                 /* We got a hard error in write_msgs but have
 908                                  * already queued this message. Report an error
 909                                  * in the socket, but don't affect return value
 910                                  * from sendmsg
 911                                  */
 912                                 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
 913                                 report_csk_error(&kcm->sk, -err);
 914                         }
 915                 }
 916         } else {
 917                 /* Message not complete, save state */
 918 partial_message:
 919                 if (head) {
 920                         kcm->seq_skb = head;
 921                         kcm_tx_msg(head)->last_skb = skb;
 922                 }
 923         }
 924
 925         KCM_STATS_ADD(kcm->stats.tx_bytes, copied);
 926
 927         release_sock(sk);
 928         return copied;
 929
 930 out_error:
 931         kcm_push(kcm);
 932
 933         if (copied && sock->type == SOCK_SEQPACKET) {
 934                 /* Wrote some bytes before encountering an
 935                  * error, return partial success.
 936                  */
 937                 goto partial_message;
 938         }
 939
 940         if (head != kcm->seq_skb)
 941                 kfree_skb(head);
 942
 943         err = sk_stream_error(sk, msg->msg_flags, err);
 944
 945         /* make sure we wake any epoll edge trigger waiter */
 946         if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
 947                 sk->sk_write_space(sk);
 948
 949         release_sock(sk);
 950         return err;
 951 }
 952
 953 static void kcm_splice_eof(struct socket *sock)
 954 {
 955         struct sock *sk = sock->sk;
 956         struct kcm_sock *kcm = kcm_sk(sk);
 957
 958         if (skb_queue_empty_lockless(&sk->sk_write_queue))
 959                 return;
 960
 961         lock_sock(sk);
 962         kcm_write_msgs(kcm);
 963         release_sock(sk);
 964 }
 965
 966 static int kcm_recvmsg(struct socket *sock, struct msghdr *msg,
 967                        size_t len, int flags)
 968 {
 969         struct sock *sk = sock->sk;
 970         struct kcm_sock *kcm = kcm_sk(sk);
 971         int err = 0;
 972         struct strp_msg *stm;
 973         int copied = 0;
 974         struct sk_buff *skb;
 975
 976         skb = skb_recv_datagram(sk, flags, &err);
 977         if (!skb)
 978                 goto out;
 979
 980         /* Okay, have a message on the receive queue */
 981
 982         stm = strp_msg(skb);
 983
 984         if (len > stm->full_len)
 985                 len = stm->full_len;
 986
 987         err = skb_copy_datagram_msg(skb, stm->offset, msg, len);
 988         if (err < 0)
 989                 goto out;
 990
 991         copied = len;
 992         if (likely(!(flags & MSG_PEEK))) {
 993                 KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
 994                 if (copied < stm->full_len) {
 995                         if (sock->type == SOCK_DGRAM) {
 996                                 /* Truncated message */
 997                                 msg->msg_flags |= MSG_TRUNC;
 998                                 goto msg_finished;
 999                         }
1000                         stm->offset += copied;
1001                         stm->full_len -= copied;
1002                 } else {
1003 msg_finished:
1004                         /* Finished with message */
1005                         msg->msg_flags |= MSG_EOR;
1006                         KCM_STATS_INCR(kcm->stats.rx_msgs);
1007                 }
1008         }
1009
1010 out:
1011         skb_free_datagram(sk, skb);
1012         return copied ? : err;
1013 }
1014
1015 static ssize_t kcm_splice_read(struct socket *sock, loff_t *ppos,
1016                                struct pipe_inode_info *pipe, size_t len,
1017                                unsigned int flags)
1018 {
1019         struct sock *sk = sock->sk;
1020         struct kcm_sock *kcm = kcm_sk(sk);
1021         struct strp_msg *stm;
1022         int err = 0;
1023         ssize_t copied;
1024         struct sk_buff *skb;
1025
1026         /* Only support splice for SOCKSEQPACKET */
1027
1028         skb = skb_recv_datagram(sk, flags, &err);
1029         if (!skb)
1030                 goto err_out;
1031
1032         /* Okay, have a message on the receive queue */
1033
1034         stm = strp_msg(skb);
1035
1036         if (len > stm->full_len)
1037                 len = stm->full_len;
1038
1039         copied = skb_splice_bits(skb, sk, stm->offset, pipe, len, flags);
1040         if (copied < 0) {
1041                 err = copied;
1042                 goto err_out;
1043         }
1044
1045         KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1046
1047         stm->offset += copied;
1048         stm->full_len -= copied;
1049
1050         /* We have no way to return MSG_EOR. If all the bytes have been
1051          * read we still leave the message in the receive socket buffer.
1052          * A subsequent recvmsg needs to be done to return MSG_EOR and
1053          * finish reading the message.
1054          */
1055
1056         skb_free_datagram(sk, skb);
1057         return copied;
1058
1059 err_out:
1060         skb_free_datagram(sk, skb);
1061         return err;
1062 }
1063
1064 /* kcm sock lock held */
1065 static void kcm_recv_disable(struct kcm_sock *kcm)
1066 {
1067         struct kcm_mux *mux = kcm->mux;
1068
1069         if (kcm->rx_disabled)
1070                 return;
1071
1072         spin_lock_bh(&mux->rx_lock);
1073
1074         kcm->rx_disabled = 1;
1075
1076         /* If a psock is reserved we'll do cleanup in unreserve */
1077         if (!kcm->rx_psock) {
1078                 if (kcm->rx_wait) {
1079                         list_del(&kcm->wait_rx_list);
1080                         /* paired with lockless reads in kcm_rfree() */
1081                         WRITE_ONCE(kcm->rx_wait, false);
1082                 }
1083
1084                 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
1085         }
1086
1087         spin_unlock_bh(&mux->rx_lock);
1088 }
1089
1090 /* kcm sock lock held */
1091 static void kcm_recv_enable(struct kcm_sock *kcm)
1092 {
1093         struct kcm_mux *mux = kcm->mux;
1094
1095         if (!kcm->rx_disabled)
1096                 return;
1097
1098         spin_lock_bh(&mux->rx_lock);
1099
1100         kcm->rx_disabled = 0;
1101         kcm_rcv_ready(kcm);
1102
1103         spin_unlock_bh(&mux->rx_lock);
1104 }
1105
1106 static int kcm_setsockopt(struct socket *sock, int level, int optname,
1107                           sockptr_t optval, unsigned int optlen)
1108 {
1109         struct kcm_sock *kcm = kcm_sk(sock->sk);
1110         int val, valbool;
1111         int err = 0;
1112
1113         if (level != SOL_KCM)
1114                 return -ENOPROTOOPT;
1115
1116         if (optlen < sizeof(int))
1117                 return -EINVAL;
1118
1119         if (copy_from_sockptr(&val, optval, sizeof(int)))
1120                 return -EFAULT;
1121
1122         valbool = val ? 1 : 0;
1123
1124         switch (optname) {
1125         case KCM_RECV_DISABLE:
1126                 lock_sock(&kcm->sk);
1127                 if (valbool)
1128                         kcm_recv_disable(kcm);
1129                 else
1130                         kcm_recv_enable(kcm);
1131                 release_sock(&kcm->sk);
1132                 break;
1133         default:
1134                 err = -ENOPROTOOPT;
1135         }
1136
1137         return err;
1138 }
1139
1140 static int kcm_getsockopt(struct socket *sock, int level, int optname,
1141                           char __user *optval, int __user *optlen)
1142 {
1143         struct kcm_sock *kcm = kcm_sk(sock->sk);
1144         int val, len;
1145
1146         if (level != SOL_KCM)
1147                 return -ENOPROTOOPT;
1148
1149         if (get_user(len, optlen))
1150                 return -EFAULT;
1151
1152         len = min_t(unsigned int, len, sizeof(int));
1153         if (len < 0)
1154                 return -EINVAL;
1155
1156         switch (optname) {
1157         case KCM_RECV_DISABLE:
1158                 val = kcm->rx_disabled;
1159                 break;
1160         default:
1161                 return -ENOPROTOOPT;
1162         }
1163
1164         if (put_user(len, optlen))
1165                 return -EFAULT;
1166         if (copy_to_user(optval, &val, len))
1167                 return -EFAULT;
1168         return 0;
1169 }
1170
1171 static void init_kcm_sock(struct kcm_sock *kcm, struct kcm_mux *mux)
1172 {
1173         struct kcm_sock *tkcm;
1174         struct list_head *head;
1175         int index = 0;
1176
1177         /* For SOCK_SEQPACKET sock type, datagram_poll checks the sk_state, so
1178          * we set sk_state, otherwise epoll_wait always returns right away with
1179          * EPOLLHUP
1180          */
1181         kcm->sk.sk_state = TCP_ESTABLISHED;
1182
1183         /* Add to mux's kcm sockets list */
1184         kcm->mux = mux;
1185         spin_lock_bh(&mux->lock);
1186
1187         head = &mux->kcm_socks;
1188         list_for_each_entry(tkcm, &mux->kcm_socks, kcm_sock_list) {
1189                 if (tkcm->index != index)
1190                         break;
1191                 head = &tkcm->kcm_sock_list;
1192                 index++;
1193         }
1194
1195         list_add(&kcm->kcm_sock_list, head);
1196         kcm->index = index;
1197
1198         mux->kcm_socks_cnt++;
1199         spin_unlock_bh(&mux->lock);
1200
1201         INIT_WORK(&kcm->tx_work, kcm_tx_work);
1202
1203         spin_lock_bh(&mux->rx_lock);
1204         kcm_rcv_ready(kcm);
1205         spin_unlock_bh(&mux->rx_lock);
1206 }
1207
1208 static int kcm_attach(struct socket *sock, struct socket *csock,
1209                       struct bpf_prog *prog)
1210 {
1211         struct kcm_sock *kcm = kcm_sk(sock->sk);
1212         struct kcm_mux *mux = kcm->mux;
1213         struct sock *csk;
1214         struct kcm_psock *psock = NULL, *tpsock;
1215         struct list_head *head;
1216         int index = 0;
1217         static const struct strp_callbacks cb = {
1218                 .rcv_msg = kcm_rcv_strparser,
1219                 .parse_msg = kcm_parse_func_strparser,
1220                 .read_sock_done = kcm_read_sock_done,
1221         };
1222         int err = 0;
1223
1224         csk = csock->sk;
1225         if (!csk)
1226                 return -EINVAL;
1227
1228         lock_sock(csk);
1229
1230         /* Only allow TCP sockets to be attached for now */
1231         if ((csk->sk_family != AF_INET && csk->sk_family != AF_INET6) ||
1232             csk->sk_protocol != IPPROTO_TCP) {
1233                 err = -EOPNOTSUPP;
1234                 goto out;
1235         }
1236
1237         /* Don't allow listeners or closed sockets */
1238         if (csk->sk_state == TCP_LISTEN || csk->sk_state == TCP_CLOSE) {
1239                 err = -EOPNOTSUPP;
1240                 goto out;
1241         }
1242
1243         psock = kmem_cache_zalloc(kcm_psockp, GFP_KERNEL);
1244         if (!psock) {
1245                 err = -ENOMEM;
1246                 goto out;
1247         }
1248
1249         psock->mux = mux;
1250         psock->sk = csk;
1251         psock->bpf_prog = prog;
1252
1253         write_lock_bh(&csk->sk_callback_lock);
1254
1255         /* Check if sk_user_data is already by KCM or someone else.
1256          * Must be done under lock to prevent race conditions.
1257          */
1258         if (csk->sk_user_data) {
1259                 write_unlock_bh(&csk->sk_callback_lock);
1260                 kmem_cache_free(kcm_psockp, psock);
1261                 err = -EALREADY;
1262                 goto out;
1263         }
1264
1265         err = strp_init(&psock->strp, csk, &cb);
1266         if (err) {
1267                 write_unlock_bh(&csk->sk_callback_lock);
1268                 kmem_cache_free(kcm_psockp, psock);
1269                 goto out;
1270         }
1271
1272         psock->save_data_ready = csk->sk_data_ready;
1273         psock->save_write_space = csk->sk_write_space;
1274         psock->save_state_change = csk->sk_state_change;
1275         csk->sk_user_data = psock;
1276         csk->sk_data_ready = psock_data_ready;
1277         csk->sk_write_space = psock_write_space;
1278         csk->sk_state_change = psock_state_change;
1279
1280         write_unlock_bh(&csk->sk_callback_lock);
1281
1282         sock_hold(csk);
1283
1284         /* Finished initialization, now add the psock to the MUX. */
1285         spin_lock_bh(&mux->lock);
1286         head = &mux->psocks;
1287         list_for_each_entry(tpsock, &mux->psocks, psock_list) {
1288                 if (tpsock->index != index)
1289                         break;
1290                 head = &tpsock->psock_list;
1291                 index++;
1292         }
1293
1294         list_add(&psock->psock_list, head);
1295         psock->index = index;
1296
1297         KCM_STATS_INCR(mux->stats.psock_attach);
1298         mux->psocks_cnt++;
1299         psock_now_avail(psock);
1300         spin_unlock_bh(&mux->lock);
1301
1302         /* Schedule RX work in case there are already bytes queued */
1303         strp_check_rcv(&psock->strp);
1304
1305 out:
1306         release_sock(csk);
1307
1308         return err;
1309 }
1310
1311 static int kcm_attach_ioctl(struct socket *sock, struct kcm_attach *info)
1312 {
1313         struct socket *csock;
1314         struct bpf_prog *prog;
1315         int err;
1316
1317         csock = sockfd_lookup(info->fd, &err);
1318         if (!csock)
1319                 return -ENOENT;
1320
1321         prog = bpf_prog_get_type(info->bpf_fd, BPF_PROG_TYPE_SOCKET_FILTER);
1322         if (IS_ERR(prog)) {
1323                 err = PTR_ERR(prog);
1324                 goto out;
1325         }
1326
1327         err = kcm_attach(sock, csock, prog);
1328         if (err) {
1329                 bpf_prog_put(prog);
1330                 goto out;
1331         }
1332
1333         /* Keep reference on file also */
1334
1335         return 0;
1336 out:
1337         sockfd_put(csock);
1338         return err;
1339 }
1340
1341 static void kcm_unattach(struct kcm_psock *psock)
1342 {
1343         struct sock *csk = psock->sk;
1344         struct kcm_mux *mux = psock->mux;
1345
1346         lock_sock(csk);
1347
1348         /* Stop getting callbacks from TCP socket. After this there should
1349          * be no way to reserve a kcm for this psock.
1350          */
1351         write_lock_bh(&csk->sk_callback_lock);
1352         csk->sk_user_data = NULL;
1353         csk->sk_data_ready = psock->save_data_ready;
1354         csk->sk_write_space = psock->save_write_space;
1355         csk->sk_state_change = psock->save_state_change;
1356         strp_stop(&psock->strp);
1357
1358         if (WARN_ON(psock->rx_kcm)) {
1359                 write_unlock_bh(&csk->sk_callback_lock);
1360                 release_sock(csk);
1361                 return;
1362         }
1363
1364         spin_lock_bh(&mux->rx_lock);
1365
1366         /* Stop receiver activities. After this point psock should not be
1367          * able to get onto ready list either through callbacks or work.
1368          */
1369         if (psock->ready_rx_msg) {
1370                 list_del(&psock->psock_ready_list);
1371                 kfree_skb(psock->ready_rx_msg);
1372                 psock->ready_rx_msg = NULL;
1373                 KCM_STATS_INCR(mux->stats.rx_ready_drops);
1374         }
1375
1376         spin_unlock_bh(&mux->rx_lock);
1377
1378         write_unlock_bh(&csk->sk_callback_lock);
1379
1380         /* Call strp_done without sock lock */
1381         release_sock(csk);
1382         strp_done(&psock->strp);
1383         lock_sock(csk);
1384
1385         bpf_prog_put(psock->bpf_prog);
1386
1387         spin_lock_bh(&mux->lock);
1388
1389         aggregate_psock_stats(&psock->stats, &mux->aggregate_psock_stats);
1390         save_strp_stats(&psock->strp, &mux->aggregate_strp_stats);
1391
1392         KCM_STATS_INCR(mux->stats.psock_unattach);
1393
1394         if (psock->tx_kcm) {
1395                 /* psock was reserved.  Just mark it finished and we will clean
1396                  * up in the kcm paths, we need kcm lock which can not be
1397                  * acquired here.
1398                  */
1399                 KCM_STATS_INCR(mux->stats.psock_unattach_rsvd);
1400                 spin_unlock_bh(&mux->lock);
1401
1402                 /* We are unattaching a socket that is reserved. Abort the
1403                  * socket since we may be out of sync in sending on it. We need
1404                  * to do this without the mux lock.
1405                  */
1406                 kcm_abort_tx_psock(psock, EPIPE, false);
1407
1408                 spin_lock_bh(&mux->lock);
1409                 if (!psock->tx_kcm) {
1410                         /* psock now unreserved in window mux was unlocked */
1411                         goto no_reserved;
1412                 }
1413                 psock->done = 1;
1414
1415                 /* Commit done before queuing work to process it */
1416                 smp_mb();
1417
1418                 /* Queue tx work to make sure psock->done is handled */
1419                 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
1420                 spin_unlock_bh(&mux->lock);
1421         } else {
1422 no_reserved:
1423                 if (!psock->tx_stopped)
1424                         list_del(&psock->psock_avail_list);
1425                 list_del(&psock->psock_list);
1426                 mux->psocks_cnt--;
1427                 spin_unlock_bh(&mux->lock);
1428
1429                 sock_put(csk);
1430                 fput(csk->sk_socket->file);
1431                 kmem_cache_free(kcm_psockp, psock);
1432         }
1433
1434         release_sock(csk);
1435 }
1436
1437 static int kcm_unattach_ioctl(struct socket *sock, struct kcm_unattach *info)
1438 {
1439         struct kcm_sock *kcm = kcm_sk(sock->sk);
1440         struct kcm_mux *mux = kcm->mux;
1441         struct kcm_psock *psock;
1442         struct socket *csock;
1443         struct sock *csk;
1444         int err;
1445
1446         csock = sockfd_lookup(info->fd, &err);
1447         if (!csock)
1448                 return -ENOENT;
1449
1450         csk = csock->sk;
1451         if (!csk) {
1452                 err = -EINVAL;
1453                 goto out;
1454         }
1455
1456         err = -ENOENT;
1457
1458         spin_lock_bh(&mux->lock);
1459
1460         list_for_each_entry(psock, &mux->psocks, psock_list) {
1461                 if (psock->sk != csk)
1462                         continue;
1463
1464                 /* Found the matching psock */
1465
1466                 if (psock->unattaching || WARN_ON(psock->done)) {
1467                         err = -EALREADY;
1468                         break;
1469                 }
1470
1471                 psock->unattaching = 1;
1472
1473                 spin_unlock_bh(&mux->lock);
1474
1475                 /* Lower socket lock should already be held */
1476                 kcm_unattach(psock);
1477
1478                 err = 0;
1479                 goto out;
1480         }
1481
1482         spin_unlock_bh(&mux->lock);
1483
1484 out:
1485         sockfd_put(csock);
1486         return err;
1487 }
1488
1489 static struct proto kcm_proto = {
1490         .name   = "KCM",
1491         .owner  = THIS_MODULE,
1492         .obj_size = sizeof(struct kcm_sock),
1493 };
1494
1495 /* Clone a kcm socket. */
1496 static struct file *kcm_clone(struct socket *osock)
1497 {
1498         struct socket *newsock;
1499         struct sock *newsk;
1500
1501         newsock = sock_alloc();
1502         if (!newsock)
1503                 return ERR_PTR(-ENFILE);
1504
1505         newsock->type = osock->type;
1506         newsock->ops = osock->ops;
1507
1508         __module_get(newsock->ops->owner);
1509
1510         newsk = sk_alloc(sock_net(osock->sk), PF_KCM, GFP_KERNEL,
1511                          &kcm_proto, false);
1512         if (!newsk) {
1513                 sock_release(newsock);
1514                 return ERR_PTR(-ENOMEM);
1515         }
1516         sock_init_data(newsock, newsk);
1517         init_kcm_sock(kcm_sk(newsk), kcm_sk(osock->sk)->mux);
1518
1519         return sock_alloc_file(newsock, 0, osock->sk->sk_prot_creator->name);
1520 }
1521
1522 static int kcm_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
1523 {
1524         int err;
1525
1526         switch (cmd) {
1527         case SIOCKCMATTACH: {
1528                 struct kcm_attach info;
1529
1530                 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1531                         return -EFAULT;
1532
1533                 err = kcm_attach_ioctl(sock, &info);
1534
1535                 break;
1536         }
1537         case SIOCKCMUNATTACH: {
1538                 struct kcm_unattach info;
1539
1540                 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1541                         return -EFAULT;
1542
1543                 err = kcm_unattach_ioctl(sock, &info);
1544
1545                 break;
1546         }
1547         case SIOCKCMCLONE: {
1548                 struct kcm_clone info;
1549                 struct file *file;
1550
1551                 info.fd = get_unused_fd_flags(0);
1552                 if (unlikely(info.fd < 0))
1553                         return info.fd;
1554
1555                 file = kcm_clone(sock);
1556                 if (IS_ERR(file)) {
1557                         put_unused_fd(info.fd);
1558                         return PTR_ERR(file);
1559                 }
1560                 if (copy_to_user((void __user *)arg, &info,
1561                                  sizeof(info))) {
1562                         put_unused_fd(info.fd);
1563                         fput(file);
1564                         return -EFAULT;
1565                 }
1566                 fd_install(info.fd, file);
1567                 err = 0;
1568                 break;
1569         }
1570         default:
1571                 err = -ENOIOCTLCMD;
1572                 break;
1573         }
1574
1575         return err;
1576 }
1577
1578 static void free_mux(struct rcu_head *rcu)
1579 {
1580         struct kcm_mux *mux = container_of(rcu,
1581             struct kcm_mux, rcu);
1582
1583         kmem_cache_free(kcm_muxp, mux);
1584 }
1585
1586 static void release_mux(struct kcm_mux *mux)
1587 {
1588         struct kcm_net *knet = mux->knet;
1589         struct kcm_psock *psock, *tmp_psock;
1590
1591         /* Release psocks */
1592         list_for_each_entry_safe(psock, tmp_psock,
1593                                  &mux->psocks, psock_list) {
1594                 if (!WARN_ON(psock->unattaching))
1595                         kcm_unattach(psock);
1596         }
1597
1598         if (WARN_ON(mux->psocks_cnt))
1599                 return;
1600
1601         __skb_queue_purge(&mux->rx_hold_queue);
1602
1603         mutex_lock(&knet->mutex);
1604         aggregate_mux_stats(&mux->stats, &knet->aggregate_mux_stats);
1605         aggregate_psock_stats(&mux->aggregate_psock_stats,
1606                               &knet->aggregate_psock_stats);
1607         aggregate_strp_stats(&mux->aggregate_strp_stats,
1608                              &knet->aggregate_strp_stats);
1609         list_del_rcu(&mux->kcm_mux_list);
1610         knet->count--;
1611         mutex_unlock(&knet->mutex);
1612
1613         call_rcu(&mux->rcu, free_mux);
1614 }
1615
1616 static void kcm_done(struct kcm_sock *kcm)
1617 {
1618         struct kcm_mux *mux = kcm->mux;
1619         struct sock *sk = &kcm->sk;
1620         int socks_cnt;
1621
1622         spin_lock_bh(&mux->rx_lock);
1623         if (kcm->rx_psock) {
1624                 /* Cleanup in unreserve_rx_kcm */
1625                 WARN_ON(kcm->done);
1626                 kcm->rx_disabled = 1;
1627                 kcm->done = 1;
1628                 spin_unlock_bh(&mux->rx_lock);
1629                 return;
1630         }
1631
1632         if (kcm->rx_wait) {
1633                 list_del(&kcm->wait_rx_list);
1634                 /* paired with lockless reads in kcm_rfree() */
1635                 WRITE_ONCE(kcm->rx_wait, false);
1636         }
1637         /* Move any pending receive messages to other kcm sockets */
1638         requeue_rx_msgs(mux, &sk->sk_receive_queue);
1639
1640         spin_unlock_bh(&mux->rx_lock);
1641
1642         if (WARN_ON(sk_rmem_alloc_get(sk)))
1643                 return;
1644
1645         /* Detach from MUX */
1646         spin_lock_bh(&mux->lock);
1647
1648         list_del(&kcm->kcm_sock_list);
1649         mux->kcm_socks_cnt--;
1650         socks_cnt = mux->kcm_socks_cnt;
1651
1652         spin_unlock_bh(&mux->lock);
1653
1654         if (!socks_cnt) {
1655                 /* We are done with the mux now. */
1656                 release_mux(mux);
1657         }
1658
1659         WARN_ON(kcm->rx_wait);
1660
1661         sock_put(&kcm->sk);
1662 }
1663
1664 /* Called by kcm_release to close a KCM socket.
1665  * If this is the last KCM socket on the MUX, destroy the MUX.
1666  */
1667 static int kcm_release(struct socket *sock)
1668 {
1669         struct sock *sk = sock->sk;
1670         struct kcm_sock *kcm;
1671         struct kcm_mux *mux;
1672         struct kcm_psock *psock;
1673
1674         if (!sk)
1675                 return 0;
1676
1677         kcm = kcm_sk(sk);
1678         mux = kcm->mux;
1679
1680         lock_sock(sk);
1681         sock_orphan(sk);
1682         kfree_skb(kcm->seq_skb);
1683
1684         /* Purge queue under lock to avoid race condition with tx_work trying
1685          * to act when queue is nonempty. If tx_work runs after this point
1686          * it will just return.
1687          */
1688         __skb_queue_purge(&sk->sk_write_queue);
1689
1690         /* Set tx_stopped. This is checked when psock is bound to a kcm and we
1691          * get a writespace callback. This prevents further work being queued
1692          * from the callback (unbinding the psock occurs after canceling work.
1693          */
1694         kcm->tx_stopped = 1;
1695
1696         release_sock(sk);
1697
1698         spin_lock_bh(&mux->lock);
1699         if (kcm->tx_wait) {
1700                 /* Take of tx_wait list, after this point there should be no way
1701                  * that a psock will be assigned to this kcm.
1702                  */
1703                 list_del(&kcm->wait_psock_list);
1704                 kcm->tx_wait = false;
1705         }
1706         spin_unlock_bh(&mux->lock);
1707
1708         /* Cancel work. After this point there should be no outside references
1709          * to the kcm socket.
1710          */
1711         cancel_work_sync(&kcm->tx_work);
1712
1713         lock_sock(sk);
1714         psock = kcm->tx_psock;
1715         if (psock) {
1716                 /* A psock was reserved, so we need to kill it since it
1717                  * may already have some bytes queued from a message. We
1718                  * need to do this after removing kcm from tx_wait list.
1719                  */
1720                 kcm_abort_tx_psock(psock, EPIPE, false);
1721                 unreserve_psock(kcm);
1722         }
1723         release_sock(sk);
1724
1725         WARN_ON(kcm->tx_wait);
1726         WARN_ON(kcm->tx_psock);
1727
1728         sock->sk = NULL;
1729
1730         kcm_done(kcm);
1731
1732         return 0;
1733 }
1734
1735 static const struct proto_ops kcm_dgram_ops = {
1736         .family =       PF_KCM,
1737         .owner =        THIS_MODULE,
1738         .release =      kcm_release,
1739         .bind =         sock_no_bind,
1740         .connect =      sock_no_connect,
1741         .socketpair =   sock_no_socketpair,
1742         .accept =       sock_no_accept,
1743         .getname =      sock_no_getname,
1744         .poll =         datagram_poll,
1745         .ioctl =        kcm_ioctl,
1746         .listen =       sock_no_listen,
1747         .shutdown =     sock_no_shutdown,
1748         .setsockopt =   kcm_setsockopt,
1749         .getsockopt =   kcm_getsockopt,
1750         .sendmsg =      kcm_sendmsg,
1751         .recvmsg =      kcm_recvmsg,
1752         .mmap =         sock_no_mmap,
1753         .splice_eof =   kcm_splice_eof,
1754 };
1755
1756 static const struct proto_ops kcm_seqpacket_ops = {
1757         .family =       PF_KCM,
1758         .owner =        THIS_MODULE,
1759         .release =      kcm_release,
1760         .bind =         sock_no_bind,
1761         .connect =      sock_no_connect,
1762         .socketpair =   sock_no_socketpair,
1763         .accept =       sock_no_accept,
1764         .getname =      sock_no_getname,
1765         .poll =         datagram_poll,
1766         .ioctl =        kcm_ioctl,
1767         .listen =       sock_no_listen,
1768         .shutdown =     sock_no_shutdown,
1769         .setsockopt =   kcm_setsockopt,
1770         .getsockopt =   kcm_getsockopt,
1771         .sendmsg =      kcm_sendmsg,
1772         .recvmsg =      kcm_recvmsg,
1773         .mmap =         sock_no_mmap,
1774         .splice_eof =   kcm_splice_eof,
1775         .splice_read =  kcm_splice_read,
1776 };
1777
1778 /* Create proto operation for kcm sockets */
1779 static int kcm_create(struct net *net, struct socket *sock,
1780                       int protocol, int kern)
1781 {
1782         struct kcm_net *knet = net_generic(net, kcm_net_id);
1783         struct sock *sk;
1784         struct kcm_mux *mux;
1785
1786         switch (sock->type) {
1787         case SOCK_DGRAM:
1788                 sock->ops = &kcm_dgram_ops;
1789                 break;
1790         case SOCK_SEQPACKET:
1791                 sock->ops = &kcm_seqpacket_ops;
1792                 break;
1793         default:
1794                 return -ESOCKTNOSUPPORT;
1795         }
1796
1797         if (protocol != KCMPROTO_CONNECTED)
1798                 return -EPROTONOSUPPORT;
1799
1800         sk = sk_alloc(net, PF_KCM, GFP_KERNEL, &kcm_proto, kern);
1801         if (!sk)
1802                 return -ENOMEM;
1803
1804         /* Allocate a kcm mux, shared between KCM sockets */
1805         mux = kmem_cache_zalloc(kcm_muxp, GFP_KERNEL);
1806         if (!mux) {
1807                 sk_free(sk);
1808                 return -ENOMEM;
1809         }
1810
1811         spin_lock_init(&mux->lock);
1812         spin_lock_init(&mux->rx_lock);
1813         INIT_LIST_HEAD(&mux->kcm_socks);
1814         INIT_LIST_HEAD(&mux->kcm_rx_waiters);
1815         INIT_LIST_HEAD(&mux->kcm_tx_waiters);
1816
1817         INIT_LIST_HEAD(&mux->psocks);
1818         INIT_LIST_HEAD(&mux->psocks_ready);
1819         INIT_LIST_HEAD(&mux->psocks_avail);
1820
1821         mux->knet = knet;
1822
1823         /* Add new MUX to list */
1824         mutex_lock(&knet->mutex);
1825         list_add_rcu(&mux->kcm_mux_list, &knet->mux_list);
1826         knet->count++;
1827         mutex_unlock(&knet->mutex);
1828
1829         skb_queue_head_init(&mux->rx_hold_queue);
1830
1831         /* Init KCM socket */
1832         sock_init_data(sock, sk);
1833         init_kcm_sock(kcm_sk(sk), mux);
1834
1835         return 0;
1836 }
1837
1838 static const struct net_proto_family kcm_family_ops = {
1839         .family = PF_KCM,
1840         .create = kcm_create,
1841         .owner  = THIS_MODULE,
1842 };
1843
1844 static __net_init int kcm_init_net(struct net *net)
1845 {
1846         struct kcm_net *knet = net_generic(net, kcm_net_id);
1847
1848         INIT_LIST_HEAD_RCU(&knet->mux_list);
1849         mutex_init(&knet->mutex);
1850
1851         return 0;
1852 }
1853
1854 static __net_exit void kcm_exit_net(struct net *net)
1855 {
1856         struct kcm_net *knet = net_generic(net, kcm_net_id);
1857
1858         /* All KCM sockets should be closed at this point, which should mean
1859          * that all multiplexors and psocks have been destroyed.
1860          */
1861         WARN_ON(!list_empty(&knet->mux_list));
1862 }
1863
1864 static struct pernet_operations kcm_net_ops = {
1865         .init = kcm_init_net,
1866         .exit = kcm_exit_net,
1867         .id   = &kcm_net_id,
1868         .size = sizeof(struct kcm_net),
1869 };
1870
1871 static int __init kcm_init(void)
1872 {
1873         int err = -ENOMEM;
1874
1875         kcm_muxp = kmem_cache_create("kcm_mux_cache",
1876                                      sizeof(struct kcm_mux), 0,
1877                                      SLAB_HWCACHE_ALIGN, NULL);
1878         if (!kcm_muxp)
1879                 goto fail;
1880
1881         kcm_psockp = kmem_cache_create("kcm_psock_cache",
1882                                        sizeof(struct kcm_psock), 0,
1883                                         SLAB_HWCACHE_ALIGN, NULL);
1884         if (!kcm_psockp)
1885                 goto fail;
1886
1887         kcm_wq = create_singlethread_workqueue("kkcmd");
1888         if (!kcm_wq)
1889                 goto fail;
1890
1891         err = proto_register(&kcm_proto, 1);
1892         if (err)
1893                 goto fail;
1894
1895         err = register_pernet_device(&kcm_net_ops);
1896         if (err)
1897                 goto net_ops_fail;
1898
1899         err = sock_register(&kcm_family_ops);
1900         if (err)
1901                 goto sock_register_fail;
1902
1903         err = kcm_proc_init();
1904         if (err)
1905                 goto proc_init_fail;
1906
1907         return 0;
1908
1909 proc_init_fail:
1910         sock_unregister(PF_KCM);
1911
1912 sock_register_fail:
1913         unregister_pernet_device(&kcm_net_ops);
1914
1915 net_ops_fail:
1916         proto_unregister(&kcm_proto);
1917
1918 fail:
1919         kmem_cache_destroy(kcm_muxp);
1920         kmem_cache_destroy(kcm_psockp);
1921
1922         if (kcm_wq)
1923                 destroy_workqueue(kcm_wq);
1924
1925         return err;
1926 }
1927
1928 static void __exit kcm_exit(void)
1929 {
1930         kcm_proc_exit();
1931         sock_unregister(PF_KCM);
1932         unregister_pernet_device(&kcm_net_ops);
1933         proto_unregister(&kcm_proto);
1934         destroy_workqueue(kcm_wq);
1935
1936         kmem_cache_destroy(kcm_muxp);
1937         kmem_cache_destroy(kcm_psockp);
1938 }
1939
1940 module_init(kcm_init);
1941 module_exit(kcm_exit);
1942
1943 MODULE_LICENSE("GPL");
1944 MODULE_ALIAS_NETPROTO(PF_KCM);