net/kcm/kcmsock.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Kernel Connection Multiplexor
   4  *
   5  * Copyright (c) 2016 Tom Herbert <tom@herbertland.com>
   6  */
   7
   8 #include <linux/bpf.h>
   9 #include <linux/errno.h>
  10 #include <linux/errqueue.h>
  11 #include <linux/file.h>
  12 #include <linux/filter.h>
  13 #include <linux/in.h>
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/net.h>
  17 #include <linux/netdevice.h>
  18 #include <linux/poll.h>
  19 #include <linux/rculist.h>
  20 #include <linux/skbuff.h>
  21 #include <linux/socket.h>
  22 #include <linux/uaccess.h>
  23 #include <linux/workqueue.h>
  24 #include <linux/syscalls.h>
  25 #include <linux/sched/signal.h>
  26
  27 #include <net/kcm.h>
  28 #include <net/netns/generic.h>
  29 #include <net/sock.h>
  30 #include <uapi/linux/kcm.h>
  31 #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                     WARN_ON_ONCE(!skb_frag_page(&skb_shinfo(skb)->frags[0]))) {
 632                         ret = -EINVAL;
 633                         goto out;
 634                 }
 635
 636                 msize = 0;
 637                 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
 638                         msize += skb_frag_size(&skb_shinfo(skb)->frags[i]);
 639
 640                 iov_iter_bvec(&msg.msg_iter, ITER_SOURCE,
 641                               (const struct bio_vec *)skb_shinfo(skb)->frags,
 642                               skb_shinfo(skb)->nr_frags, msize);
 643                 iov_iter_advance(&msg.msg_iter, txm->frag_offset);
 644
 645                 do {
 646                         ret = sock_sendmsg(psock->sk->sk_socket, &msg);
 647                         if (ret <= 0) {
 648                                 if (ret == -EAGAIN) {
 649                                         /* Save state to try again when there's
 650                                          * write space on the socket
 651                                          */
 652                                         txm->frag_skb = skb;
 653                                         ret = 0;
 654                                         goto out;
 655                                 }
 656
 657                                 /* Hard failure in sending message, abort this
 658                                  * psock since it has lost framing
 659                                  * synchronization and retry sending the
 660                                  * message from the beginning.
 661                                  */
 662                                 kcm_abort_tx_psock(psock, ret ? -ret : EPIPE,
 663                                                    true);
 664                                 unreserve_psock(kcm);
 665                                 psock = NULL;
 666
 667                                 txm->started_tx = false;
 668                                 kcm_report_tx_retry(kcm);
 669                                 ret = 0;
 670                                 goto retry;
 671                         }
 672
 673                         txm->sent += ret;
 674                         txm->frag_offset += ret;
 675                         KCM_STATS_ADD(psock->stats.tx_bytes, ret);
 676                 } while (msg.msg_iter.count > 0);
 677
 678                 if (skb == head) {
 679                         if (skb_has_frag_list(skb)) {
 680                                 txm->frag_skb = skb_shinfo(skb)->frag_list;
 681                                 txm->frag_offset = 0;
 682                                 continue;
 683                         }
 684                 } else if (skb->next) {
 685                         txm->frag_skb = skb->next;
 686                         txm->frag_offset = 0;
 687                         continue;
 688                 }
 689
 690                 /* Successfully sent the whole packet, account for it. */
 691                 sk->sk_wmem_queued -= txm->sent;
 692                 total_sent += txm->sent;
 693                 skb_dequeue(&sk->sk_write_queue);
 694                 kfree_skb(head);
 695                 KCM_STATS_INCR(psock->stats.tx_msgs);
 696         }
 697 out:
 698         if (!head) {
 699                 /* Done with all queued messages. */
 700                 WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
 701                 if (psock)
 702                         unreserve_psock(kcm);
 703         }
 704
 705         /* Check if write space is available */
 706         sk->sk_write_space(sk);
 707
 708         return total_sent ? : ret;
 709 }
 710
 711 static void kcm_tx_work(struct work_struct *w)
 712 {
 713         struct kcm_sock *kcm = container_of(w, struct kcm_sock, tx_work);
 714         struct sock *sk = &kcm->sk;
 715         int err;
 716
 717         lock_sock(sk);
 718
 719         /* Primarily for SOCK_DGRAM sockets, also handle asynchronous tx
 720          * aborts
 721          */
 722         err = kcm_write_msgs(kcm);
 723         if (err < 0) {
 724                 /* Hard failure in write, report error on KCM socket */
 725                 pr_warn("KCM: Hard failure on kcm_write_msgs %d\n", err);
 726                 report_csk_error(&kcm->sk, -err);
 727                 goto out;
 728         }
 729
 730         /* Primarily for SOCK_SEQPACKET sockets */
 731         if (likely(sk->sk_socket) &&
 732             test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
 733                 clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 734                 sk->sk_write_space(sk);
 735         }
 736
 737 out:
 738         release_sock(sk);
 739 }
 740
 741 static void kcm_push(struct kcm_sock *kcm)
 742 {
 743         if (kcm->tx_wait_more)
 744                 kcm_write_msgs(kcm);
 745 }
 746
 747 static int kcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 748 {
 749         struct sock *sk = sock->sk;
 750         struct kcm_sock *kcm = kcm_sk(sk);
 751         struct sk_buff *skb = NULL, *head = NULL;
 752         size_t copy, copied = 0;
 753         long timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
 754         int eor = (sock->type == SOCK_DGRAM) ?
 755                   !(msg->msg_flags & MSG_MORE) : !!(msg->msg_flags & MSG_EOR);
 756         int err = -EPIPE;
 757
 758         mutex_lock(&kcm->tx_mutex);
 759         lock_sock(sk);
 760
 761         /* Per tcp_sendmsg this should be in poll */
 762         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 763
 764         if (sk->sk_err)
 765                 goto out_error;
 766
 767         if (kcm->seq_skb) {
 768                 /* Previously opened message */
 769                 head = kcm->seq_skb;
 770                 skb = kcm_tx_msg(head)->last_skb;
 771                 goto start;
 772         }
 773
 774         /* Call the sk_stream functions to manage the sndbuf mem. */
 775         if (!sk_stream_memory_free(sk)) {
 776                 kcm_push(kcm);
 777                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 778                 err = sk_stream_wait_memory(sk, &timeo);
 779                 if (err)
 780                         goto out_error;
 781         }
 782
 783         if (msg_data_left(msg)) {
 784                 /* New message, alloc head skb */
 785                 head = alloc_skb(0, sk->sk_allocation);
 786                 while (!head) {
 787                         kcm_push(kcm);
 788                         err = sk_stream_wait_memory(sk, &timeo);
 789                         if (err)
 790                                 goto out_error;
 791
 792                         head = alloc_skb(0, sk->sk_allocation);
 793                 }
 794
 795                 skb = head;
 796
 797                 /* Set ip_summed to CHECKSUM_UNNECESSARY to avoid calling
 798                  * csum_and_copy_from_iter from skb_do_copy_data_nocache.
 799                  */
 800                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 801         }
 802
 803 start:
 804         while (msg_data_left(msg)) {
 805                 bool merge = true;
 806                 int i = skb_shinfo(skb)->nr_frags;
 807                 struct page_frag *pfrag = sk_page_frag(sk);
 808
 809                 if (!sk_page_frag_refill(sk, pfrag))
 810                         goto wait_for_memory;
 811
 812                 if (!skb_can_coalesce(skb, i, pfrag->page,
 813                                       pfrag->offset)) {
 814                         if (i == MAX_SKB_FRAGS) {
 815                                 struct sk_buff *tskb;
 816
 817                                 tskb = alloc_skb(0, sk->sk_allocation);
 818                                 if (!tskb)
 819                                         goto wait_for_memory;
 820
 821                                 if (head == skb)
 822                                         skb_shinfo(head)->frag_list = tskb;
 823                                 else
 824                                         skb->next = tskb;
 825
 826                                 skb = tskb;
 827                                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 828                                 continue;
 829                         }
 830                         merge = false;
 831                 }
 832
 833                 if (msg->msg_flags & MSG_SPLICE_PAGES) {
 834                         copy = msg_data_left(msg);
 835                         if (!sk_wmem_schedule(sk, copy))
 836                                 goto wait_for_memory;
 837
 838                         err = skb_splice_from_iter(skb, &msg->msg_iter, copy,
 839                                                    sk->sk_allocation);
 840                         if (err < 0) {
 841                                 if (err == -EMSGSIZE)
 842                                         goto wait_for_memory;
 843                                 goto out_error;
 844                         }
 845
 846                         copy = err;
 847                         skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
 848                         sk_wmem_queued_add(sk, copy);
 849                         sk_mem_charge(sk, copy);
 850
 851                         if (head != skb)
 852                                 head->truesize += copy;
 853                 } else {
 854                         copy = min_t(int, msg_data_left(msg),
 855                                      pfrag->size - pfrag->offset);
 856                         if (!sk_wmem_schedule(sk, copy))
 857                                 goto wait_for_memory;
 858
 859                         err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
 860                                                        pfrag->page,
 861                                                        pfrag->offset,
 862                                                        copy);
 863                         if (err)
 864                                 goto out_error;
 865
 866                         /* Update the skb. */
 867                         if (merge) {
 868                                 skb_frag_size_add(
 869                                         &skb_shinfo(skb)->frags[i - 1], copy);
 870                         } else {
 871                                 skb_fill_page_desc(skb, i, pfrag->page,
 872                                                    pfrag->offset, copy);
 873                                 get_page(pfrag->page);
 874                         }
 875
 876                         pfrag->offset += copy;
 877                 }
 878
 879                 copied += copy;
 880                 if (head != skb) {
 881                         head->len += copy;
 882                         head->data_len += copy;
 883                 }
 884
 885                 continue;
 886
 887 wait_for_memory:
 888                 kcm_push(kcm);
 889                 err = sk_stream_wait_memory(sk, &timeo);
 890                 if (err)
 891                         goto out_error;
 892         }
 893
 894         if (eor) {
 895                 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
 896
 897                 if (head) {
 898                         /* Message complete, queue it on send buffer */
 899                         __skb_queue_tail(&sk->sk_write_queue, head);
 900                         kcm->seq_skb = NULL;
 901                         KCM_STATS_INCR(kcm->stats.tx_msgs);
 902                 }
 903
 904                 if (msg->msg_flags & MSG_BATCH) {
 905                         kcm->tx_wait_more = true;
 906                 } else if (kcm->tx_wait_more || not_busy) {
 907                         err = kcm_write_msgs(kcm);
 908                         if (err < 0) {
 909                                 /* We got a hard error in write_msgs but have
 910                                  * already queued this message. Report an error
 911                                  * in the socket, but don't affect return value
 912                                  * from sendmsg
 913                                  */
 914                                 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
 915                                 report_csk_error(&kcm->sk, -err);
 916                         }
 917                 }
 918         } else {
 919                 /* Message not complete, save state */
 920 partial_message:
 921                 if (head) {
 922                         kcm->seq_skb = head;
 923                         kcm_tx_msg(head)->last_skb = skb;
 924                 }
 925         }
 926
 927         KCM_STATS_ADD(kcm->stats.tx_bytes, copied);
 928
 929         release_sock(sk);
 930         mutex_unlock(&kcm->tx_mutex);
 931         return copied;
 932
 933 out_error:
 934         kcm_push(kcm);
 935
 936         if (sock->type == SOCK_SEQPACKET) {
 937                 /* Wrote some bytes before encountering an
 938                  * error, return partial success.
 939                  */
 940                 if (copied)
 941                         goto partial_message;
 942                 if (head != kcm->seq_skb)
 943                         kfree_skb(head);
 944         } else {
 945                 kfree_skb(head);
 946                 kcm->seq_skb = NULL;
 947         }
 948
 949         err = sk_stream_error(sk, msg->msg_flags, err);
 950
 951         /* make sure we wake any epoll edge trigger waiter */
 952         if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
 953                 sk->sk_write_space(sk);
 954
 955         release_sock(sk);
 956         mutex_unlock(&kcm->tx_mutex);
 957         return err;
 958 }
 959
 960 static void kcm_splice_eof(struct socket *sock)
 961 {
 962         struct sock *sk = sock->sk;
 963         struct kcm_sock *kcm = kcm_sk(sk);
 964
 965         if (skb_queue_empty_lockless(&sk->sk_write_queue))
 966                 return;
 967
 968         lock_sock(sk);
 969         kcm_write_msgs(kcm);
 970         release_sock(sk);
 971 }
 972
 973 static int kcm_recvmsg(struct socket *sock, struct msghdr *msg,
 974                        size_t len, int flags)
 975 {
 976         struct sock *sk = sock->sk;
 977         struct kcm_sock *kcm = kcm_sk(sk);
 978         int err = 0;
 979         struct strp_msg *stm;
 980         int copied = 0;
 981         struct sk_buff *skb;
 982
 983         skb = skb_recv_datagram(sk, flags, &err);
 984         if (!skb)
 985                 goto out;
 986
 987         /* Okay, have a message on the receive queue */
 988
 989         stm = strp_msg(skb);
 990
 991         if (len > stm->full_len)
 992                 len = stm->full_len;
 993
 994         err = skb_copy_datagram_msg(skb, stm->offset, msg, len);
 995         if (err < 0)
 996                 goto out;
 997
 998         copied = len;
 999         if (likely(!(flags & MSG_PEEK))) {
1000                 KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1001                 if (copied < stm->full_len) {
1002                         if (sock->type == SOCK_DGRAM) {
1003                                 /* Truncated message */
1004                                 msg->msg_flags |= MSG_TRUNC;
1005                                 goto msg_finished;
1006                         }
1007                         stm->offset += copied;
1008                         stm->full_len -= copied;
1009                 } else {
1010 msg_finished:
1011                         /* Finished with message */
1012                         msg->msg_flags |= MSG_EOR;
1013                         KCM_STATS_INCR(kcm->stats.rx_msgs);
1014                 }
1015         }
1016
1017 out:
1018         skb_free_datagram(sk, skb);
1019         return copied ? : err;
1020 }
1021
1022 static ssize_t kcm_splice_read(struct socket *sock, loff_t *ppos,
1023                                struct pipe_inode_info *pipe, size_t len,
1024                                unsigned int flags)
1025 {
1026         struct sock *sk = sock->sk;
1027         struct kcm_sock *kcm = kcm_sk(sk);
1028         struct strp_msg *stm;
1029         int err = 0;
1030         ssize_t copied;
1031         struct sk_buff *skb;
1032
1033         /* Only support splice for SOCKSEQPACKET */
1034
1035         skb = skb_recv_datagram(sk, flags, &err);
1036         if (!skb)
1037                 goto err_out;
1038
1039         /* Okay, have a message on the receive queue */
1040
1041         stm = strp_msg(skb);
1042
1043         if (len > stm->full_len)
1044                 len = stm->full_len;
1045
1046         copied = skb_splice_bits(skb, sk, stm->offset, pipe, len, flags);
1047         if (copied < 0) {
1048                 err = copied;
1049                 goto err_out;
1050         }
1051
1052         KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1053
1054         stm->offset += copied;
1055         stm->full_len -= copied;
1056
1057         /* We have no way to return MSG_EOR. If all the bytes have been
1058          * read we still leave the message in the receive socket buffer.
1059          * A subsequent recvmsg needs to be done to return MSG_EOR and
1060          * finish reading the message.
1061          */
1062
1063         skb_free_datagram(sk, skb);
1064         return copied;
1065
1066 err_out:
1067         skb_free_datagram(sk, skb);
1068         return err;
1069 }
1070
1071 /* kcm sock lock held */
1072 static void kcm_recv_disable(struct kcm_sock *kcm)
1073 {
1074         struct kcm_mux *mux = kcm->mux;
1075
1076         if (kcm->rx_disabled)
1077                 return;
1078
1079         spin_lock_bh(&mux->rx_lock);
1080
1081         kcm->rx_disabled = 1;
1082
1083         /* If a psock is reserved we'll do cleanup in unreserve */
1084         if (!kcm->rx_psock) {
1085                 if (kcm->rx_wait) {
1086                         list_del(&kcm->wait_rx_list);
1087                         /* paired with lockless reads in kcm_rfree() */
1088                         WRITE_ONCE(kcm->rx_wait, false);
1089                 }
1090
1091                 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
1092         }
1093
1094         spin_unlock_bh(&mux->rx_lock);
1095 }
1096
1097 /* kcm sock lock held */
1098 static void kcm_recv_enable(struct kcm_sock *kcm)
1099 {
1100         struct kcm_mux *mux = kcm->mux;
1101
1102         if (!kcm->rx_disabled)
1103                 return;
1104
1105         spin_lock_bh(&mux->rx_lock);
1106
1107         kcm->rx_disabled = 0;
1108         kcm_rcv_ready(kcm);
1109
1110         spin_unlock_bh(&mux->rx_lock);
1111 }
1112
1113 static int kcm_setsockopt(struct socket *sock, int level, int optname,
1114                           sockptr_t optval, unsigned int optlen)
1115 {
1116         struct kcm_sock *kcm = kcm_sk(sock->sk);
1117         int val, valbool;
1118         int err = 0;
1119
1120         if (level != SOL_KCM)
1121                 return -ENOPROTOOPT;
1122
1123         if (optlen < sizeof(int))
1124                 return -EINVAL;
1125
1126         if (copy_from_sockptr(&val, optval, sizeof(int)))
1127                 return -EFAULT;
1128
1129         valbool = val ? 1 : 0;
1130
1131         switch (optname) {
1132         case KCM_RECV_DISABLE:
1133                 lock_sock(&kcm->sk);
1134                 if (valbool)
1135                         kcm_recv_disable(kcm);
1136                 else
1137                         kcm_recv_enable(kcm);
1138                 release_sock(&kcm->sk);
1139                 break;
1140         default:
1141                 err = -ENOPROTOOPT;
1142         }
1143
1144         return err;
1145 }
1146
1147 static int kcm_getsockopt(struct socket *sock, int level, int optname,
1148                           char __user *optval, int __user *optlen)
1149 {
1150         struct kcm_sock *kcm = kcm_sk(sock->sk);
1151         int val, len;
1152
1153         if (level != SOL_KCM)
1154                 return -ENOPROTOOPT;
1155
1156         if (get_user(len, optlen))
1157                 return -EFAULT;
1158
1159         if (len < 0)
1160                 return -EINVAL;
1161
1162         len = min_t(unsigned int, len, sizeof(int));
1163
1164         switch (optname) {
1165         case KCM_RECV_DISABLE:
1166                 val = kcm->rx_disabled;
1167                 break;
1168         default:
1169                 return -ENOPROTOOPT;
1170         }
1171
1172         if (put_user(len, optlen))
1173                 return -EFAULT;
1174         if (copy_to_user(optval, &val, len))
1175                 return -EFAULT;
1176         return 0;
1177 }
1178
1179 static void init_kcm_sock(struct kcm_sock *kcm, struct kcm_mux *mux)
1180 {
1181         struct kcm_sock *tkcm;
1182         struct list_head *head;
1183         int index = 0;
1184
1185         /* For SOCK_SEQPACKET sock type, datagram_poll checks the sk_state, so
1186          * we set sk_state, otherwise epoll_wait always returns right away with
1187          * EPOLLHUP
1188          */
1189         kcm->sk.sk_state = TCP_ESTABLISHED;
1190
1191         /* Add to mux's kcm sockets list */
1192         kcm->mux = mux;
1193         spin_lock_bh(&mux->lock);
1194
1195         head = &mux->kcm_socks;
1196         list_for_each_entry(tkcm, &mux->kcm_socks, kcm_sock_list) {
1197                 if (tkcm->index != index)
1198                         break;
1199                 head = &tkcm->kcm_sock_list;
1200                 index++;
1201         }
1202
1203         list_add(&kcm->kcm_sock_list, head);
1204         kcm->index = index;
1205
1206         mux->kcm_socks_cnt++;
1207         spin_unlock_bh(&mux->lock);
1208
1209         INIT_WORK(&kcm->tx_work, kcm_tx_work);
1210         mutex_init(&kcm->tx_mutex);
1211
1212         spin_lock_bh(&mux->rx_lock);
1213         kcm_rcv_ready(kcm);
1214         spin_unlock_bh(&mux->rx_lock);
1215 }
1216
1217 static int kcm_attach(struct socket *sock, struct socket *csock,
1218                       struct bpf_prog *prog)
1219 {
1220         struct kcm_sock *kcm = kcm_sk(sock->sk);
1221         struct kcm_mux *mux = kcm->mux;
1222         struct sock *csk;
1223         struct kcm_psock *psock = NULL, *tpsock;
1224         struct list_head *head;
1225         int index = 0;
1226         static const struct strp_callbacks cb = {
1227                 .rcv_msg = kcm_rcv_strparser,
1228                 .parse_msg = kcm_parse_func_strparser,
1229                 .read_sock_done = kcm_read_sock_done,
1230         };
1231         int err = 0;
1232
1233         csk = csock->sk;
1234         if (!csk)
1235                 return -EINVAL;
1236
1237         lock_sock(csk);
1238
1239         /* Only allow TCP sockets to be attached for now */
1240         if ((csk->sk_family != AF_INET && csk->sk_family != AF_INET6) ||
1241             csk->sk_protocol != IPPROTO_TCP) {
1242                 err = -EOPNOTSUPP;
1243                 goto out;
1244         }
1245
1246         /* Don't allow listeners or closed sockets */
1247         if (csk->sk_state == TCP_LISTEN || csk->sk_state == TCP_CLOSE) {
1248                 err = -EOPNOTSUPP;
1249                 goto out;
1250         }
1251
1252         psock = kmem_cache_zalloc(kcm_psockp, GFP_KERNEL);
1253         if (!psock) {
1254                 err = -ENOMEM;
1255                 goto out;
1256         }
1257
1258         psock->mux = mux;
1259         psock->sk = csk;
1260         psock->bpf_prog = prog;
1261
1262         write_lock_bh(&csk->sk_callback_lock);
1263
1264         /* Check if sk_user_data is already by KCM or someone else.
1265          * Must be done under lock to prevent race conditions.
1266          */
1267         if (csk->sk_user_data) {
1268                 write_unlock_bh(&csk->sk_callback_lock);
1269                 kmem_cache_free(kcm_psockp, psock);
1270                 err = -EALREADY;
1271                 goto out;
1272         }
1273
1274         err = strp_init(&psock->strp, csk, &cb);
1275         if (err) {
1276                 write_unlock_bh(&csk->sk_callback_lock);
1277                 kmem_cache_free(kcm_psockp, psock);
1278                 goto out;
1279         }
1280
1281         psock->save_data_ready = csk->sk_data_ready;
1282         psock->save_write_space = csk->sk_write_space;
1283         psock->save_state_change = csk->sk_state_change;
1284         csk->sk_user_data = psock;
1285         csk->sk_data_ready = psock_data_ready;
1286         csk->sk_write_space = psock_write_space;
1287         csk->sk_state_change = psock_state_change;
1288
1289         write_unlock_bh(&csk->sk_callback_lock);
1290
1291         sock_hold(csk);
1292
1293         /* Finished initialization, now add the psock to the MUX. */
1294         spin_lock_bh(&mux->lock);
1295         head = &mux->psocks;
1296         list_for_each_entry(tpsock, &mux->psocks, psock_list) {
1297                 if (tpsock->index != index)
1298                         break;
1299                 head = &tpsock->psock_list;
1300                 index++;
1301         }
1302
1303         list_add(&psock->psock_list, head);
1304         psock->index = index;
1305
1306         KCM_STATS_INCR(mux->stats.psock_attach);
1307         mux->psocks_cnt++;
1308         psock_now_avail(psock);
1309         spin_unlock_bh(&mux->lock);
1310
1311         /* Schedule RX work in case there are already bytes queued */
1312         strp_check_rcv(&psock->strp);
1313
1314 out:
1315         release_sock(csk);
1316
1317         return err;
1318 }
1319
1320 static int kcm_attach_ioctl(struct socket *sock, struct kcm_attach *info)
1321 {
1322         struct socket *csock;
1323         struct bpf_prog *prog;
1324         int err;
1325
1326         csock = sockfd_lookup(info->fd, &err);
1327         if (!csock)
1328                 return -ENOENT;
1329
1330         prog = bpf_prog_get_type(info->bpf_fd, BPF_PROG_TYPE_SOCKET_FILTER);
1331         if (IS_ERR(prog)) {
1332                 err = PTR_ERR(prog);
1333                 goto out;
1334         }
1335
1336         err = kcm_attach(sock, csock, prog);
1337         if (err) {
1338                 bpf_prog_put(prog);
1339                 goto out;
1340         }
1341
1342         /* Keep reference on file also */
1343
1344         return 0;
1345 out:
1346         sockfd_put(csock);
1347         return err;
1348 }
1349
1350 static void kcm_unattach(struct kcm_psock *psock)
1351 {
1352         struct sock *csk = psock->sk;
1353         struct kcm_mux *mux = psock->mux;
1354
1355         lock_sock(csk);
1356
1357         /* Stop getting callbacks from TCP socket. After this there should
1358          * be no way to reserve a kcm for this psock.
1359          */
1360         write_lock_bh(&csk->sk_callback_lock);
1361         csk->sk_user_data = NULL;
1362         csk->sk_data_ready = psock->save_data_ready;
1363         csk->sk_write_space = psock->save_write_space;
1364         csk->sk_state_change = psock->save_state_change;
1365         strp_stop(&psock->strp);
1366
1367         if (WARN_ON(psock->rx_kcm)) {
1368                 write_unlock_bh(&csk->sk_callback_lock);
1369                 release_sock(csk);
1370                 return;
1371         }
1372
1373         spin_lock_bh(&mux->rx_lock);
1374
1375         /* Stop receiver activities. After this point psock should not be
1376          * able to get onto ready list either through callbacks or work.
1377          */
1378         if (psock->ready_rx_msg) {
1379                 list_del(&psock->psock_ready_list);
1380                 kfree_skb(psock->ready_rx_msg);
1381                 psock->ready_rx_msg = NULL;
1382                 KCM_STATS_INCR(mux->stats.rx_ready_drops);
1383         }
1384
1385         spin_unlock_bh(&mux->rx_lock);
1386
1387         write_unlock_bh(&csk->sk_callback_lock);
1388
1389         /* Call strp_done without sock lock */
1390         release_sock(csk);
1391         strp_done(&psock->strp);
1392         lock_sock(csk);
1393
1394         bpf_prog_put(psock->bpf_prog);
1395
1396         spin_lock_bh(&mux->lock);
1397
1398         aggregate_psock_stats(&psock->stats, &mux->aggregate_psock_stats);
1399         save_strp_stats(&psock->strp, &mux->aggregate_strp_stats);
1400
1401         KCM_STATS_INCR(mux->stats.psock_unattach);
1402
1403         if (psock->tx_kcm) {
1404                 /* psock was reserved.  Just mark it finished and we will clean
1405                  * up in the kcm paths, we need kcm lock which can not be
1406                  * acquired here.
1407                  */
1408                 KCM_STATS_INCR(mux->stats.psock_unattach_rsvd);
1409                 spin_unlock_bh(&mux->lock);
1410
1411                 /* We are unattaching a socket that is reserved. Abort the
1412                  * socket since we may be out of sync in sending on it. We need
1413                  * to do this without the mux lock.
1414                  */
1415                 kcm_abort_tx_psock(psock, EPIPE, false);
1416
1417                 spin_lock_bh(&mux->lock);
1418                 if (!psock->tx_kcm) {
1419                         /* psock now unreserved in window mux was unlocked */
1420                         goto no_reserved;
1421                 }
1422                 psock->done = 1;
1423
1424                 /* Commit done before queuing work to process it */
1425                 smp_mb();
1426
1427                 /* Queue tx work to make sure psock->done is handled */
1428                 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
1429                 spin_unlock_bh(&mux->lock);
1430         } else {
1431 no_reserved:
1432                 if (!psock->tx_stopped)
1433                         list_del(&psock->psock_avail_list);
1434                 list_del(&psock->psock_list);
1435                 mux->psocks_cnt--;
1436                 spin_unlock_bh(&mux->lock);
1437
1438                 sock_put(csk);
1439                 fput(csk->sk_socket->file);
1440                 kmem_cache_free(kcm_psockp, psock);
1441         }
1442
1443         release_sock(csk);
1444 }
1445
1446 static int kcm_unattach_ioctl(struct socket *sock, struct kcm_unattach *info)
1447 {
1448         struct kcm_sock *kcm = kcm_sk(sock->sk);
1449         struct kcm_mux *mux = kcm->mux;
1450         struct kcm_psock *psock;
1451         struct socket *csock;
1452         struct sock *csk;
1453         int err;
1454
1455         csock = sockfd_lookup(info->fd, &err);
1456         if (!csock)
1457                 return -ENOENT;
1458
1459         csk = csock->sk;
1460         if (!csk) {
1461                 err = -EINVAL;
1462                 goto out;
1463         }
1464
1465         err = -ENOENT;
1466
1467         spin_lock_bh(&mux->lock);
1468
1469         list_for_each_entry(psock, &mux->psocks, psock_list) {
1470                 if (psock->sk != csk)
1471                         continue;
1472
1473                 /* Found the matching psock */
1474
1475                 if (psock->unattaching || WARN_ON(psock->done)) {
1476                         err = -EALREADY;
1477                         break;
1478                 }
1479
1480                 psock->unattaching = 1;
1481
1482                 spin_unlock_bh(&mux->lock);
1483
1484                 /* Lower socket lock should already be held */
1485                 kcm_unattach(psock);
1486
1487                 err = 0;
1488                 goto out;
1489         }
1490
1491         spin_unlock_bh(&mux->lock);
1492
1493 out:
1494         sockfd_put(csock);
1495         return err;
1496 }
1497
1498 static struct proto kcm_proto = {
1499         .name   = "KCM",
1500         .owner  = THIS_MODULE,
1501         .obj_size = sizeof(struct kcm_sock),
1502 };
1503
1504 /* Clone a kcm socket. */
1505 static struct file *kcm_clone(struct socket *osock)
1506 {
1507         struct socket *newsock;
1508         struct sock *newsk;
1509
1510         newsock = sock_alloc();
1511         if (!newsock)
1512                 return ERR_PTR(-ENFILE);
1513
1514         newsock->type = osock->type;
1515         newsock->ops = osock->ops;
1516
1517         __module_get(newsock->ops->owner);
1518
1519         newsk = sk_alloc(sock_net(osock->sk), PF_KCM, GFP_KERNEL,
1520                          &kcm_proto, false);
1521         if (!newsk) {
1522                 sock_release(newsock);
1523                 return ERR_PTR(-ENOMEM);
1524         }
1525         sock_init_data(newsock, newsk);
1526         init_kcm_sock(kcm_sk(newsk), kcm_sk(osock->sk)->mux);
1527
1528         return sock_alloc_file(newsock, 0, osock->sk->sk_prot_creator->name);
1529 }
1530
1531 static int kcm_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
1532 {
1533         int err;
1534
1535         switch (cmd) {
1536         case SIOCKCMATTACH: {
1537                 struct kcm_attach info;
1538
1539                 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1540                         return -EFAULT;
1541
1542                 err = kcm_attach_ioctl(sock, &info);
1543
1544                 break;
1545         }
1546         case SIOCKCMUNATTACH: {
1547                 struct kcm_unattach info;
1548
1549                 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1550                         return -EFAULT;
1551
1552                 err = kcm_unattach_ioctl(sock, &info);
1553
1554                 break;
1555         }
1556         case SIOCKCMCLONE: {
1557                 struct kcm_clone info;
1558                 struct file *file;
1559
1560                 info.fd = get_unused_fd_flags(0);
1561                 if (unlikely(info.fd < 0))
1562                         return info.fd;
1563
1564                 file = kcm_clone(sock);
1565                 if (IS_ERR(file)) {
1566                         put_unused_fd(info.fd);
1567                         return PTR_ERR(file);
1568                 }
1569                 if (copy_to_user((void __user *)arg, &info,
1570                                  sizeof(info))) {
1571                         put_unused_fd(info.fd);
1572                         fput(file);
1573                         return -EFAULT;
1574                 }
1575                 fd_install(info.fd, file);
1576                 err = 0;
1577                 break;
1578         }
1579         default:
1580                 err = -ENOIOCTLCMD;
1581                 break;
1582         }
1583
1584         return err;
1585 }
1586
1587 static void free_mux(struct rcu_head *rcu)
1588 {
1589         struct kcm_mux *mux = container_of(rcu,
1590             struct kcm_mux, rcu);
1591
1592         kmem_cache_free(kcm_muxp, mux);
1593 }
1594
1595 static void release_mux(struct kcm_mux *mux)
1596 {
1597         struct kcm_net *knet = mux->knet;
1598         struct kcm_psock *psock, *tmp_psock;
1599
1600         /* Release psocks */
1601         list_for_each_entry_safe(psock, tmp_psock,
1602                                  &mux->psocks, psock_list) {
1603                 if (!WARN_ON(psock->unattaching))
1604                         kcm_unattach(psock);
1605         }
1606
1607         if (WARN_ON(mux->psocks_cnt))
1608                 return;
1609
1610         __skb_queue_purge(&mux->rx_hold_queue);
1611
1612         mutex_lock(&knet->mutex);
1613         aggregate_mux_stats(&mux->stats, &knet->aggregate_mux_stats);
1614         aggregate_psock_stats(&mux->aggregate_psock_stats,
1615                               &knet->aggregate_psock_stats);
1616         aggregate_strp_stats(&mux->aggregate_strp_stats,
1617                              &knet->aggregate_strp_stats);
1618         list_del_rcu(&mux->kcm_mux_list);
1619         knet->count--;
1620         mutex_unlock(&knet->mutex);
1621
1622         call_rcu(&mux->rcu, free_mux);
1623 }
1624
1625 static void kcm_done(struct kcm_sock *kcm)
1626 {
1627         struct kcm_mux *mux = kcm->mux;
1628         struct sock *sk = &kcm->sk;
1629         int socks_cnt;
1630
1631         spin_lock_bh(&mux->rx_lock);
1632         if (kcm->rx_psock) {
1633                 /* Cleanup in unreserve_rx_kcm */
1634                 WARN_ON(kcm->done);
1635                 kcm->rx_disabled = 1;
1636                 kcm->done = 1;
1637                 spin_unlock_bh(&mux->rx_lock);
1638                 return;
1639         }
1640
1641         if (kcm->rx_wait) {
1642                 list_del(&kcm->wait_rx_list);
1643                 /* paired with lockless reads in kcm_rfree() */
1644                 WRITE_ONCE(kcm->rx_wait, false);
1645         }
1646         /* Move any pending receive messages to other kcm sockets */
1647         requeue_rx_msgs(mux, &sk->sk_receive_queue);
1648
1649         spin_unlock_bh(&mux->rx_lock);
1650
1651         if (WARN_ON(sk_rmem_alloc_get(sk)))
1652                 return;
1653
1654         /* Detach from MUX */
1655         spin_lock_bh(&mux->lock);
1656
1657         list_del(&kcm->kcm_sock_list);
1658         mux->kcm_socks_cnt--;
1659         socks_cnt = mux->kcm_socks_cnt;
1660
1661         spin_unlock_bh(&mux->lock);
1662
1663         if (!socks_cnt) {
1664                 /* We are done with the mux now. */
1665                 release_mux(mux);
1666         }
1667
1668         WARN_ON(kcm->rx_wait);
1669
1670         sock_put(&kcm->sk);
1671 }
1672
1673 /* Called by kcm_release to close a KCM socket.
1674  * If this is the last KCM socket on the MUX, destroy the MUX.
1675  */
1676 static int kcm_release(struct socket *sock)
1677 {
1678         struct sock *sk = sock->sk;
1679         struct kcm_sock *kcm;
1680         struct kcm_mux *mux;
1681         struct kcm_psock *psock;
1682
1683         if (!sk)
1684                 return 0;
1685
1686         kcm = kcm_sk(sk);
1687         mux = kcm->mux;
1688
1689         lock_sock(sk);
1690         sock_orphan(sk);
1691         kfree_skb(kcm->seq_skb);
1692
1693         /* Purge queue under lock to avoid race condition with tx_work trying
1694          * to act when queue is nonempty. If tx_work runs after this point
1695          * it will just return.
1696          */
1697         __skb_queue_purge(&sk->sk_write_queue);
1698
1699         /* Set tx_stopped. This is checked when psock is bound to a kcm and we
1700          * get a writespace callback. This prevents further work being queued
1701          * from the callback (unbinding the psock occurs after canceling work.
1702          */
1703         kcm->tx_stopped = 1;
1704
1705         release_sock(sk);
1706
1707         spin_lock_bh(&mux->lock);
1708         if (kcm->tx_wait) {
1709                 /* Take of tx_wait list, after this point there should be no way
1710                  * that a psock will be assigned to this kcm.
1711                  */
1712                 list_del(&kcm->wait_psock_list);
1713                 kcm->tx_wait = false;
1714         }
1715         spin_unlock_bh(&mux->lock);
1716
1717         /* Cancel work. After this point there should be no outside references
1718          * to the kcm socket.
1719          */
1720         cancel_work_sync(&kcm->tx_work);
1721
1722         lock_sock(sk);
1723         psock = kcm->tx_psock;
1724         if (psock) {
1725                 /* A psock was reserved, so we need to kill it since it
1726                  * may already have some bytes queued from a message. We
1727                  * need to do this after removing kcm from tx_wait list.
1728                  */
1729                 kcm_abort_tx_psock(psock, EPIPE, false);
1730                 unreserve_psock(kcm);
1731         }
1732         release_sock(sk);
1733
1734         WARN_ON(kcm->tx_wait);
1735         WARN_ON(kcm->tx_psock);
1736
1737         sock->sk = NULL;
1738
1739         kcm_done(kcm);
1740
1741         return 0;
1742 }
1743
1744 static const struct proto_ops kcm_dgram_ops = {
1745         .family =       PF_KCM,
1746         .owner =        THIS_MODULE,
1747         .release =      kcm_release,
1748         .bind =         sock_no_bind,
1749         .connect =      sock_no_connect,
1750         .socketpair =   sock_no_socketpair,
1751         .accept =       sock_no_accept,
1752         .getname =      sock_no_getname,
1753         .poll =         datagram_poll,
1754         .ioctl =        kcm_ioctl,
1755         .listen =       sock_no_listen,
1756         .shutdown =     sock_no_shutdown,
1757         .setsockopt =   kcm_setsockopt,
1758         .getsockopt =   kcm_getsockopt,
1759         .sendmsg =      kcm_sendmsg,
1760         .recvmsg =      kcm_recvmsg,
1761         .mmap =         sock_no_mmap,
1762         .splice_eof =   kcm_splice_eof,
1763 };
1764
1765 static const struct proto_ops kcm_seqpacket_ops = {
1766         .family =       PF_KCM,
1767         .owner =        THIS_MODULE,
1768         .release =      kcm_release,
1769         .bind =         sock_no_bind,
1770         .connect =      sock_no_connect,
1771         .socketpair =   sock_no_socketpair,
1772         .accept =       sock_no_accept,
1773         .getname =      sock_no_getname,
1774         .poll =         datagram_poll,
1775         .ioctl =        kcm_ioctl,
1776         .listen =       sock_no_listen,
1777         .shutdown =     sock_no_shutdown,
1778         .setsockopt =   kcm_setsockopt,
1779         .getsockopt =   kcm_getsockopt,
1780         .sendmsg =      kcm_sendmsg,
1781         .recvmsg =      kcm_recvmsg,
1782         .mmap =         sock_no_mmap,
1783         .splice_eof =   kcm_splice_eof,
1784         .splice_read =  kcm_splice_read,
1785 };
1786
1787 /* Create proto operation for kcm sockets */
1788 static int kcm_create(struct net *net, struct socket *sock,
1789                       int protocol, int kern)
1790 {
1791         struct kcm_net *knet = net_generic(net, kcm_net_id);
1792         struct sock *sk;
1793         struct kcm_mux *mux;
1794
1795         switch (sock->type) {
1796         case SOCK_DGRAM:
1797                 sock->ops = &kcm_dgram_ops;
1798                 break;
1799         case SOCK_SEQPACKET:
1800                 sock->ops = &kcm_seqpacket_ops;
1801                 break;
1802         default:
1803                 return -ESOCKTNOSUPPORT;
1804         }
1805
1806         if (protocol != KCMPROTO_CONNECTED)
1807                 return -EPROTONOSUPPORT;
1808
1809         sk = sk_alloc(net, PF_KCM, GFP_KERNEL, &kcm_proto, kern);
1810         if (!sk)
1811                 return -ENOMEM;
1812
1813         /* Allocate a kcm mux, shared between KCM sockets */
1814         mux = kmem_cache_zalloc(kcm_muxp, GFP_KERNEL);
1815         if (!mux) {
1816                 sk_free(sk);
1817                 return -ENOMEM;
1818         }
1819
1820         spin_lock_init(&mux->lock);
1821         spin_lock_init(&mux->rx_lock);
1822         INIT_LIST_HEAD(&mux->kcm_socks);
1823         INIT_LIST_HEAD(&mux->kcm_rx_waiters);
1824         INIT_LIST_HEAD(&mux->kcm_tx_waiters);
1825
1826         INIT_LIST_HEAD(&mux->psocks);
1827         INIT_LIST_HEAD(&mux->psocks_ready);
1828         INIT_LIST_HEAD(&mux->psocks_avail);
1829
1830         mux->knet = knet;
1831
1832         /* Add new MUX to list */
1833         mutex_lock(&knet->mutex);
1834         list_add_rcu(&mux->kcm_mux_list, &knet->mux_list);
1835         knet->count++;
1836         mutex_unlock(&knet->mutex);
1837
1838         skb_queue_head_init(&mux->rx_hold_queue);
1839
1840         /* Init KCM socket */
1841         sock_init_data(sock, sk);
1842         init_kcm_sock(kcm_sk(sk), mux);
1843
1844         return 0;
1845 }
1846
1847 static const struct net_proto_family kcm_family_ops = {
1848         .family = PF_KCM,
1849         .create = kcm_create,
1850         .owner  = THIS_MODULE,
1851 };
1852
1853 static __net_init int kcm_init_net(struct net *net)
1854 {
1855         struct kcm_net *knet = net_generic(net, kcm_net_id);
1856
1857         INIT_LIST_HEAD_RCU(&knet->mux_list);
1858         mutex_init(&knet->mutex);
1859
1860         return 0;
1861 }
1862
1863 static __net_exit void kcm_exit_net(struct net *net)
1864 {
1865         struct kcm_net *knet = net_generic(net, kcm_net_id);
1866
1867         /* All KCM sockets should be closed at this point, which should mean
1868          * that all multiplexors and psocks have been destroyed.
1869          */
1870         WARN_ON(!list_empty(&knet->mux_list));
1871
1872         mutex_destroy(&knet->mutex);
1873 }
1874
1875 static struct pernet_operations kcm_net_ops = {
1876         .init = kcm_init_net,
1877         .exit = kcm_exit_net,
1878         .id   = &kcm_net_id,
1879         .size = sizeof(struct kcm_net),
1880 };
1881
1882 static int __init kcm_init(void)
1883 {
1884         int err = -ENOMEM;
1885
1886         kcm_muxp = KMEM_CACHE(kcm_mux, SLAB_HWCACHE_ALIGN);
1887         if (!kcm_muxp)
1888                 goto fail;
1889
1890         kcm_psockp = KMEM_CACHE(kcm_psock, SLAB_HWCACHE_ALIGN);
1891         if (!kcm_psockp)
1892                 goto fail;
1893
1894         kcm_wq = create_singlethread_workqueue("kkcmd");
1895         if (!kcm_wq)
1896                 goto fail;
1897
1898         err = proto_register(&kcm_proto, 1);
1899         if (err)
1900                 goto fail;
1901
1902         err = register_pernet_device(&kcm_net_ops);
1903         if (err)
1904                 goto net_ops_fail;
1905
1906         err = sock_register(&kcm_family_ops);
1907         if (err)
1908                 goto sock_register_fail;
1909
1910         err = kcm_proc_init();
1911         if (err)
1912                 goto proc_init_fail;
1913
1914         return 0;
1915
1916 proc_init_fail:
1917         sock_unregister(PF_KCM);
1918
1919 sock_register_fail:
1920         unregister_pernet_device(&kcm_net_ops);
1921
1922 net_ops_fail:
1923         proto_unregister(&kcm_proto);
1924
1925 fail:
1926         kmem_cache_destroy(kcm_muxp);
1927         kmem_cache_destroy(kcm_psockp);
1928
1929         if (kcm_wq)
1930                 destroy_workqueue(kcm_wq);
1931
1932         return err;
1933 }
1934
1935 static void __exit kcm_exit(void)
1936 {
1937         kcm_proc_exit();
1938         sock_unregister(PF_KCM);
1939         unregister_pernet_device(&kcm_net_ops);
1940         proto_unregister(&kcm_proto);
1941         destroy_workqueue(kcm_wq);
1942
1943         kmem_cache_destroy(kcm_muxp);
1944         kmem_cache_destroy(kcm_psockp);
1945 }
1946
1947 module_init(kcm_init);
1948 module_exit(kcm_exit);
1949
1950 MODULE_LICENSE("GPL");
1951 MODULE_DESCRIPTION("KCM (Kernel Connection Multiplexor) sockets");
1952 MODULE_ALIAS_NETPROTO(PF_KCM);