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/in.h>
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/net.h>
  16 #include <linux/netdevice.h>
  17 #include <linux/poll.h>
  18 #include <linux/rculist.h>
  19 #include <linux/skbuff.h>
  20 #include <linux/socket.h>
  21 #include <linux/uaccess.h>
  22 #include <linux/workqueue.h>
  23 #include <linux/syscalls.h>
  24 #include <linux/sched/signal.h>
  25
  26 #include <net/kcm.h>
  27 #include <net/netns/generic.h>
  28 #include <net/sock.h>
  29 #include <uapi/linux/kcm.h>
  30
  31 unsigned int kcm_net_id;
  32
  33 static struct kmem_cache *kcm_psockp __read_mostly;
  34 static struct kmem_cache *kcm_muxp __read_mostly;
  35 static struct workqueue_struct *kcm_wq;
  36
  37 static inline struct kcm_sock *kcm_sk(const struct sock *sk)
  38 {
  39         return (struct kcm_sock *)sk;
  40 }
  41
  42 static inline struct kcm_tx_msg *kcm_tx_msg(struct sk_buff *skb)
  43 {
  44         return (struct kcm_tx_msg *)skb->cb;
  45 }
  46
  47 static void report_csk_error(struct sock *csk, int err)
  48 {
  49         csk->sk_err = EPIPE;
  50         csk->sk_error_report(csk);
  51 }
  52
  53 static void kcm_abort_tx_psock(struct kcm_psock *psock, int err,
  54                                bool wakeup_kcm)
  55 {
  56         struct sock *csk = psock->sk;
  57         struct kcm_mux *mux = psock->mux;
  58
  59         /* Unrecoverable error in transmit */
  60
  61         spin_lock_bh(&mux->lock);
  62
  63         if (psock->tx_stopped) {
  64                 spin_unlock_bh(&mux->lock);
  65                 return;
  66         }
  67
  68         psock->tx_stopped = 1;
  69         KCM_STATS_INCR(psock->stats.tx_aborts);
  70
  71         if (!psock->tx_kcm) {
  72                 /* Take off psocks_avail list */
  73                 list_del(&psock->psock_avail_list);
  74         } else if (wakeup_kcm) {
  75                 /* In this case psock is being aborted while outside of
  76                  * write_msgs and psock is reserved. Schedule tx_work
  77                  * to handle the failure there. Need to commit tx_stopped
  78                  * before queuing work.
  79                  */
  80                 smp_mb();
  81
  82                 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
  83         }
  84
  85         spin_unlock_bh(&mux->lock);
  86
  87         /* Report error on lower socket */
  88         report_csk_error(csk, err);
  89 }
  90
  91 /* RX mux lock held. */
  92 static void kcm_update_rx_mux_stats(struct kcm_mux *mux,
  93                                     struct kcm_psock *psock)
  94 {
  95         STRP_STATS_ADD(mux->stats.rx_bytes,
  96                        psock->strp.stats.bytes -
  97                        psock->saved_rx_bytes);
  98         mux->stats.rx_msgs +=
  99                 psock->strp.stats.msgs - psock->saved_rx_msgs;
 100         psock->saved_rx_msgs = psock->strp.stats.msgs;
 101         psock->saved_rx_bytes = psock->strp.stats.bytes;
 102 }
 103
 104 static void kcm_update_tx_mux_stats(struct kcm_mux *mux,
 105                                     struct kcm_psock *psock)
 106 {
 107         KCM_STATS_ADD(mux->stats.tx_bytes,
 108                       psock->stats.tx_bytes - psock->saved_tx_bytes);
 109         mux->stats.tx_msgs +=
 110                 psock->stats.tx_msgs - psock->saved_tx_msgs;
 111         psock->saved_tx_msgs = psock->stats.tx_msgs;
 112         psock->saved_tx_bytes = psock->stats.tx_bytes;
 113 }
 114
 115 static int kcm_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
 116
 117 /* KCM is ready to receive messages on its queue-- either the KCM is new or
 118  * has become unblocked after being blocked on full socket buffer. Queue any
 119  * pending ready messages on a psock. RX mux lock held.
 120  */
 121 static void kcm_rcv_ready(struct kcm_sock *kcm)
 122 {
 123         struct kcm_mux *mux = kcm->mux;
 124         struct kcm_psock *psock;
 125         struct sk_buff *skb;
 126
 127         if (unlikely(kcm->rx_wait || kcm->rx_psock || kcm->rx_disabled))
 128                 return;
 129
 130         while (unlikely((skb = __skb_dequeue(&mux->rx_hold_queue)))) {
 131                 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
 132                         /* Assuming buffer limit has been reached */
 133                         skb_queue_head(&mux->rx_hold_queue, skb);
 134                         WARN_ON(!sk_rmem_alloc_get(&kcm->sk));
 135                         return;
 136                 }
 137         }
 138
 139         while (!list_empty(&mux->psocks_ready)) {
 140                 psock = list_first_entry(&mux->psocks_ready, struct kcm_psock,
 141                                          psock_ready_list);
 142
 143                 if (kcm_queue_rcv_skb(&kcm->sk, psock->ready_rx_msg)) {
 144                         /* Assuming buffer limit has been reached */
 145                         WARN_ON(!sk_rmem_alloc_get(&kcm->sk));
 146                         return;
 147                 }
 148
 149                 /* Consumed the ready message on the psock. Schedule rx_work to
 150                  * get more messages.
 151                  */
 152                 list_del(&psock->psock_ready_list);
 153                 psock->ready_rx_msg = NULL;
 154                 /* Commit clearing of ready_rx_msg for queuing work */
 155                 smp_mb();
 156
 157                 strp_unpause(&psock->strp);
 158                 strp_check_rcv(&psock->strp);
 159         }
 160
 161         /* Buffer limit is okay now, add to ready list */
 162         list_add_tail(&kcm->wait_rx_list,
 163                       &kcm->mux->kcm_rx_waiters);
 164         kcm->rx_wait = true;
 165 }
 166
 167 static void kcm_rfree(struct sk_buff *skb)
 168 {
 169         struct sock *sk = skb->sk;
 170         struct kcm_sock *kcm = kcm_sk(sk);
 171         struct kcm_mux *mux = kcm->mux;
 172         unsigned int len = skb->truesize;
 173
 174         sk_mem_uncharge(sk, len);
 175         atomic_sub(len, &sk->sk_rmem_alloc);
 176
 177         /* For reading rx_wait and rx_psock without holding lock */
 178         smp_mb__after_atomic();
 179
 180         if (!kcm->rx_wait && !kcm->rx_psock &&
 181             sk_rmem_alloc_get(sk) < sk->sk_rcvlowat) {
 182                 spin_lock_bh(&mux->rx_lock);
 183                 kcm_rcv_ready(kcm);
 184                 spin_unlock_bh(&mux->rx_lock);
 185         }
 186 }
 187
 188 static int kcm_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 189 {
 190         struct sk_buff_head *list = &sk->sk_receive_queue;
 191
 192         if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
 193                 return -ENOMEM;
 194
 195         if (!sk_rmem_schedule(sk, skb, skb->truesize))
 196                 return -ENOBUFS;
 197
 198         skb->dev = NULL;
 199
 200         skb_orphan(skb);
 201         skb->sk = sk;
 202         skb->destructor = kcm_rfree;
 203         atomic_add(skb->truesize, &sk->sk_rmem_alloc);
 204         sk_mem_charge(sk, skb->truesize);
 205
 206         skb_queue_tail(list, skb);
 207
 208         if (!sock_flag(sk, SOCK_DEAD))
 209                 sk->sk_data_ready(sk);
 210
 211         return 0;
 212 }
 213
 214 /* Requeue received messages for a kcm socket to other kcm sockets. This is
 215  * called with a kcm socket is receive disabled.
 216  * RX mux lock held.
 217  */
 218 static void requeue_rx_msgs(struct kcm_mux *mux, struct sk_buff_head *head)
 219 {
 220         struct sk_buff *skb;
 221         struct kcm_sock *kcm;
 222
 223         while ((skb = __skb_dequeue(head))) {
 224                 /* Reset destructor to avoid calling kcm_rcv_ready */
 225                 skb->destructor = sock_rfree;
 226                 skb_orphan(skb);
 227 try_again:
 228                 if (list_empty(&mux->kcm_rx_waiters)) {
 229                         skb_queue_tail(&mux->rx_hold_queue, skb);
 230                         continue;
 231                 }
 232
 233                 kcm = list_first_entry(&mux->kcm_rx_waiters,
 234                                        struct kcm_sock, wait_rx_list);
 235
 236                 if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
 237                         /* Should mean socket buffer full */
 238                         list_del(&kcm->wait_rx_list);
 239                         kcm->rx_wait = false;
 240
 241                         /* Commit rx_wait to read in kcm_free */
 242                         smp_wmb();
 243
 244                         goto try_again;
 245                 }
 246         }
 247 }
 248
 249 /* Lower sock lock held */
 250 static struct kcm_sock *reserve_rx_kcm(struct kcm_psock *psock,
 251                                        struct sk_buff *head)
 252 {
 253         struct kcm_mux *mux = psock->mux;
 254         struct kcm_sock *kcm;
 255
 256         WARN_ON(psock->ready_rx_msg);
 257
 258         if (psock->rx_kcm)
 259                 return psock->rx_kcm;
 260
 261         spin_lock_bh(&mux->rx_lock);
 262
 263         if (psock->rx_kcm) {
 264                 spin_unlock_bh(&mux->rx_lock);
 265                 return psock->rx_kcm;
 266         }
 267
 268         kcm_update_rx_mux_stats(mux, psock);
 269
 270         if (list_empty(&mux->kcm_rx_waiters)) {
 271                 psock->ready_rx_msg = head;
 272                 strp_pause(&psock->strp);
 273                 list_add_tail(&psock->psock_ready_list,
 274                               &mux->psocks_ready);
 275                 spin_unlock_bh(&mux->rx_lock);
 276                 return NULL;
 277         }
 278
 279         kcm = list_first_entry(&mux->kcm_rx_waiters,
 280                                struct kcm_sock, wait_rx_list);
 281         list_del(&kcm->wait_rx_list);
 282         kcm->rx_wait = false;
 283
 284         psock->rx_kcm = kcm;
 285         kcm->rx_psock = psock;
 286
 287         spin_unlock_bh(&mux->rx_lock);
 288
 289         return kcm;
 290 }
 291
 292 static void kcm_done(struct kcm_sock *kcm);
 293
 294 static void kcm_done_work(struct work_struct *w)
 295 {
 296         kcm_done(container_of(w, struct kcm_sock, done_work));
 297 }
 298
 299 /* Lower sock held */
 300 static void unreserve_rx_kcm(struct kcm_psock *psock,
 301                              bool rcv_ready)
 302 {
 303         struct kcm_sock *kcm = psock->rx_kcm;
 304         struct kcm_mux *mux = psock->mux;
 305
 306         if (!kcm)
 307                 return;
 308
 309         spin_lock_bh(&mux->rx_lock);
 310
 311         psock->rx_kcm = NULL;
 312         kcm->rx_psock = NULL;
 313
 314         /* Commit kcm->rx_psock before sk_rmem_alloc_get to sync with
 315          * kcm_rfree
 316          */
 317         smp_mb();
 318
 319         if (unlikely(kcm->done)) {
 320                 spin_unlock_bh(&mux->rx_lock);
 321
 322                 /* Need to run kcm_done in a task since we need to qcquire
 323                  * callback locks which may already be held here.
 324                  */
 325                 INIT_WORK(&kcm->done_work, kcm_done_work);
 326                 schedule_work(&kcm->done_work);
 327                 return;
 328         }
 329
 330         if (unlikely(kcm->rx_disabled)) {
 331                 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
 332         } else if (rcv_ready || unlikely(!sk_rmem_alloc_get(&kcm->sk))) {
 333                 /* Check for degenerative race with rx_wait that all
 334                  * data was dequeued (accounted for in kcm_rfree).
 335                  */
 336                 kcm_rcv_ready(kcm);
 337         }
 338         spin_unlock_bh(&mux->rx_lock);
 339 }
 340
 341 /* Lower sock lock held */
 342 static void psock_data_ready(struct sock *sk)
 343 {
 344         struct kcm_psock *psock;
 345
 346         read_lock_bh(&sk->sk_callback_lock);
 347
 348         psock = (struct kcm_psock *)sk->sk_user_data;
 349         if (likely(psock))
 350                 strp_data_ready(&psock->strp);
 351
 352         read_unlock_bh(&sk->sk_callback_lock);
 353 }
 354
 355 /* Called with lower sock held */
 356 static void kcm_rcv_strparser(struct strparser *strp, struct sk_buff *skb)
 357 {
 358         struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
 359         struct kcm_sock *kcm;
 360
 361 try_queue:
 362         kcm = reserve_rx_kcm(psock, skb);
 363         if (!kcm) {
 364                  /* Unable to reserve a KCM, message is held in psock and strp
 365                   * is paused.
 366                   */
 367                 return;
 368         }
 369
 370         if (kcm_queue_rcv_skb(&kcm->sk, skb)) {
 371                 /* Should mean socket buffer full */
 372                 unreserve_rx_kcm(psock, false);
 373                 goto try_queue;
 374         }
 375 }
 376
 377 static int kcm_parse_func_strparser(struct strparser *strp, struct sk_buff *skb)
 378 {
 379         struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
 380         struct bpf_prog *prog = psock->bpf_prog;
 381         int res;
 382
 383         res = bpf_prog_run_pin_on_cpu(prog, skb);
 384         return res;
 385 }
 386
 387 static int kcm_read_sock_done(struct strparser *strp, int err)
 388 {
 389         struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
 390
 391         unreserve_rx_kcm(psock, true);
 392
 393         return err;
 394 }
 395
 396 static void psock_state_change(struct sock *sk)
 397 {
 398         /* TCP only does a EPOLLIN for a half close. Do a EPOLLHUP here
 399          * since application will normally not poll with EPOLLIN
 400          * on the TCP sockets.
 401          */
 402
 403         report_csk_error(sk, EPIPE);
 404 }
 405
 406 static void psock_write_space(struct sock *sk)
 407 {
 408         struct kcm_psock *psock;
 409         struct kcm_mux *mux;
 410         struct kcm_sock *kcm;
 411
 412         read_lock_bh(&sk->sk_callback_lock);
 413
 414         psock = (struct kcm_psock *)sk->sk_user_data;
 415         if (unlikely(!psock))
 416                 goto out;
 417         mux = psock->mux;
 418
 419         spin_lock_bh(&mux->lock);
 420
 421         /* Check if the socket is reserved so someone is waiting for sending. */
 422         kcm = psock->tx_kcm;
 423         if (kcm && !unlikely(kcm->tx_stopped))
 424                 queue_work(kcm_wq, &kcm->tx_work);
 425
 426         spin_unlock_bh(&mux->lock);
 427 out:
 428         read_unlock_bh(&sk->sk_callback_lock);
 429 }
 430
 431 static void unreserve_psock(struct kcm_sock *kcm);
 432
 433 /* kcm sock is locked. */
 434 static struct kcm_psock *reserve_psock(struct kcm_sock *kcm)
 435 {
 436         struct kcm_mux *mux = kcm->mux;
 437         struct kcm_psock *psock;
 438
 439         psock = kcm->tx_psock;
 440
 441         smp_rmb(); /* Must read tx_psock before tx_wait */
 442
 443         if (psock) {
 444                 WARN_ON(kcm->tx_wait);
 445                 if (unlikely(psock->tx_stopped))
 446                         unreserve_psock(kcm);
 447                 else
 448                         return kcm->tx_psock;
 449         }
 450
 451         spin_lock_bh(&mux->lock);
 452
 453         /* Check again under lock to see if psock was reserved for this
 454          * psock via psock_unreserve.
 455          */
 456         psock = kcm->tx_psock;
 457         if (unlikely(psock)) {
 458                 WARN_ON(kcm->tx_wait);
 459                 spin_unlock_bh(&mux->lock);
 460                 return kcm->tx_psock;
 461         }
 462
 463         if (!list_empty(&mux->psocks_avail)) {
 464                 psock = list_first_entry(&mux->psocks_avail,
 465                                          struct kcm_psock,
 466                                          psock_avail_list);
 467                 list_del(&psock->psock_avail_list);
 468                 if (kcm->tx_wait) {
 469                         list_del(&kcm->wait_psock_list);
 470                         kcm->tx_wait = false;
 471                 }
 472                 kcm->tx_psock = psock;
 473                 psock->tx_kcm = kcm;
 474                 KCM_STATS_INCR(psock->stats.reserved);
 475         } else if (!kcm->tx_wait) {
 476                 list_add_tail(&kcm->wait_psock_list,
 477                               &mux->kcm_tx_waiters);
 478                 kcm->tx_wait = true;
 479         }
 480
 481         spin_unlock_bh(&mux->lock);
 482
 483         return psock;
 484 }
 485
 486 /* mux lock held */
 487 static void psock_now_avail(struct kcm_psock *psock)
 488 {
 489         struct kcm_mux *mux = psock->mux;
 490         struct kcm_sock *kcm;
 491
 492         if (list_empty(&mux->kcm_tx_waiters)) {
 493                 list_add_tail(&psock->psock_avail_list,
 494                               &mux->psocks_avail);
 495         } else {
 496                 kcm = list_first_entry(&mux->kcm_tx_waiters,
 497                                        struct kcm_sock,
 498                                        wait_psock_list);
 499                 list_del(&kcm->wait_psock_list);
 500                 kcm->tx_wait = false;
 501                 psock->tx_kcm = kcm;
 502
 503                 /* Commit before changing tx_psock since that is read in
 504                  * reserve_psock before queuing work.
 505                  */
 506                 smp_mb();
 507
 508                 kcm->tx_psock = psock;
 509                 KCM_STATS_INCR(psock->stats.reserved);
 510                 queue_work(kcm_wq, &kcm->tx_work);
 511         }
 512 }
 513
 514 /* kcm sock is locked. */
 515 static void unreserve_psock(struct kcm_sock *kcm)
 516 {
 517         struct kcm_psock *psock;
 518         struct kcm_mux *mux = kcm->mux;
 519
 520         spin_lock_bh(&mux->lock);
 521
 522         psock = kcm->tx_psock;
 523
 524         if (WARN_ON(!psock)) {
 525                 spin_unlock_bh(&mux->lock);
 526                 return;
 527         }
 528
 529         smp_rmb(); /* Read tx_psock before tx_wait */
 530
 531         kcm_update_tx_mux_stats(mux, psock);
 532
 533         WARN_ON(kcm->tx_wait);
 534
 535         kcm->tx_psock = NULL;
 536         psock->tx_kcm = NULL;
 537         KCM_STATS_INCR(psock->stats.unreserved);
 538
 539         if (unlikely(psock->tx_stopped)) {
 540                 if (psock->done) {
 541                         /* Deferred free */
 542                         list_del(&psock->psock_list);
 543                         mux->psocks_cnt--;
 544                         sock_put(psock->sk);
 545                         fput(psock->sk->sk_socket->file);
 546                         kmem_cache_free(kcm_psockp, psock);
 547                 }
 548
 549                 /* Don't put back on available list */
 550
 551                 spin_unlock_bh(&mux->lock);
 552
 553                 return;
 554         }
 555
 556         psock_now_avail(psock);
 557
 558         spin_unlock_bh(&mux->lock);
 559 }
 560
 561 static void kcm_report_tx_retry(struct kcm_sock *kcm)
 562 {
 563         struct kcm_mux *mux = kcm->mux;
 564
 565         spin_lock_bh(&mux->lock);
 566         KCM_STATS_INCR(mux->stats.tx_retries);
 567         spin_unlock_bh(&mux->lock);
 568 }
 569
 570 /* Write any messages ready on the kcm socket.  Called with kcm sock lock
 571  * held.  Return bytes actually sent or error.
 572  */
 573 static int kcm_write_msgs(struct kcm_sock *kcm)
 574 {
 575         struct sock *sk = &kcm->sk;
 576         struct kcm_psock *psock;
 577         struct sk_buff *skb, *head;
 578         struct kcm_tx_msg *txm;
 579         unsigned short fragidx, frag_offset;
 580         unsigned int sent, total_sent = 0;
 581         int ret = 0;
 582
 583         kcm->tx_wait_more = false;
 584         psock = kcm->tx_psock;
 585         if (unlikely(psock && psock->tx_stopped)) {
 586                 /* A reserved psock was aborted asynchronously. Unreserve
 587                  * it and we'll retry the message.
 588                  */
 589                 unreserve_psock(kcm);
 590                 kcm_report_tx_retry(kcm);
 591                 if (skb_queue_empty(&sk->sk_write_queue))
 592                         return 0;
 593
 594                 kcm_tx_msg(skb_peek(&sk->sk_write_queue))->sent = 0;
 595
 596         } else if (skb_queue_empty(&sk->sk_write_queue)) {
 597                 return 0;
 598         }
 599
 600         head = skb_peek(&sk->sk_write_queue);
 601         txm = kcm_tx_msg(head);
 602
 603         if (txm->sent) {
 604                 /* Send of first skbuff in queue already in progress */
 605                 if (WARN_ON(!psock)) {
 606                         ret = -EINVAL;
 607                         goto out;
 608                 }
 609                 sent = txm->sent;
 610                 frag_offset = txm->frag_offset;
 611                 fragidx = txm->fragidx;
 612                 skb = txm->frag_skb;
 613
 614                 goto do_frag;
 615         }
 616
 617 try_again:
 618         psock = reserve_psock(kcm);
 619         if (!psock)
 620                 goto out;
 621
 622         do {
 623                 skb = head;
 624                 txm = kcm_tx_msg(head);
 625                 sent = 0;
 626
 627 do_frag_list:
 628                 if (WARN_ON(!skb_shinfo(skb)->nr_frags)) {
 629                         ret = -EINVAL;
 630                         goto out;
 631                 }
 632
 633                 for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags;
 634                      fragidx++) {
 635                         skb_frag_t *frag;
 636
 637                         frag_offset = 0;
 638 do_frag:
 639                         frag = &skb_shinfo(skb)->frags[fragidx];
 640                         if (WARN_ON(!skb_frag_size(frag))) {
 641                                 ret = -EINVAL;
 642                                 goto out;
 643                         }
 644
 645                         ret = kernel_sendpage(psock->sk->sk_socket,
 646                                               skb_frag_page(frag),
 647                                               skb_frag_off(frag) + frag_offset,
 648                                               skb_frag_size(frag) - frag_offset,
 649                                               MSG_DONTWAIT);
 650                         if (ret <= 0) {
 651                                 if (ret == -EAGAIN) {
 652                                         /* Save state to try again when there's
 653                                          * write space on the socket
 654                                          */
 655                                         txm->sent = sent;
 656                                         txm->frag_offset = frag_offset;
 657                                         txm->fragidx = fragidx;
 658                                         txm->frag_skb = skb;
 659
 660                                         ret = 0;
 661                                         goto out;
 662                                 }
 663
 664                                 /* Hard failure in sending message, abort this
 665                                  * psock since it has lost framing
 666                                  * synchonization and retry sending the
 667                                  * message from the beginning.
 668                                  */
 669                                 kcm_abort_tx_psock(psock, ret ? -ret : EPIPE,
 670                                                    true);
 671                                 unreserve_psock(kcm);
 672
 673                                 txm->sent = 0;
 674                                 kcm_report_tx_retry(kcm);
 675                                 ret = 0;
 676
 677                                 goto try_again;
 678                         }
 679
 680                         sent += ret;
 681                         frag_offset += ret;
 682                         KCM_STATS_ADD(psock->stats.tx_bytes, ret);
 683                         if (frag_offset < skb_frag_size(frag)) {
 684                                 /* Not finished with this frag */
 685                                 goto do_frag;
 686                         }
 687                 }
 688
 689                 if (skb == head) {
 690                         if (skb_has_frag_list(skb)) {
 691                                 skb = skb_shinfo(skb)->frag_list;
 692                                 goto do_frag_list;
 693                         }
 694                 } else if (skb->next) {
 695                         skb = skb->next;
 696                         goto do_frag_list;
 697                 }
 698
 699                 /* Successfully sent the whole packet, account for it. */
 700                 skb_dequeue(&sk->sk_write_queue);
 701                 kfree_skb(head);
 702                 sk->sk_wmem_queued -= sent;
 703                 total_sent += sent;
 704                 KCM_STATS_INCR(psock->stats.tx_msgs);
 705         } while ((head = skb_peek(&sk->sk_write_queue)));
 706 out:
 707         if (!head) {
 708                 /* Done with all queued messages. */
 709                 WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
 710                 unreserve_psock(kcm);
 711         }
 712
 713         /* Check if write space is available */
 714         sk->sk_write_space(sk);
 715
 716         return total_sent ? : ret;
 717 }
 718
 719 static void kcm_tx_work(struct work_struct *w)
 720 {
 721         struct kcm_sock *kcm = container_of(w, struct kcm_sock, tx_work);
 722         struct sock *sk = &kcm->sk;
 723         int err;
 724
 725         lock_sock(sk);
 726
 727         /* Primarily for SOCK_DGRAM sockets, also handle asynchronous tx
 728          * aborts
 729          */
 730         err = kcm_write_msgs(kcm);
 731         if (err < 0) {
 732                 /* Hard failure in write, report error on KCM socket */
 733                 pr_warn("KCM: Hard failure on kcm_write_msgs %d\n", err);
 734                 report_csk_error(&kcm->sk, -err);
 735                 goto out;
 736         }
 737
 738         /* Primarily for SOCK_SEQPACKET sockets */
 739         if (likely(sk->sk_socket) &&
 740             test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
 741                 clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 742                 sk->sk_write_space(sk);
 743         }
 744
 745 out:
 746         release_sock(sk);
 747 }
 748
 749 static void kcm_push(struct kcm_sock *kcm)
 750 {
 751         if (kcm->tx_wait_more)
 752                 kcm_write_msgs(kcm);
 753 }
 754
 755 static ssize_t kcm_sendpage(struct socket *sock, struct page *page,
 756                             int offset, size_t size, int flags)
 757
 758 {
 759         struct sock *sk = sock->sk;
 760         struct kcm_sock *kcm = kcm_sk(sk);
 761         struct sk_buff *skb = NULL, *head = NULL;
 762         long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 763         bool eor;
 764         int err = 0;
 765         int i;
 766
 767         if (flags & MSG_SENDPAGE_NOTLAST)
 768                 flags |= MSG_MORE;
 769
 770         /* No MSG_EOR from splice, only look at MSG_MORE */
 771         eor = !(flags & MSG_MORE);
 772
 773         lock_sock(sk);
 774
 775         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 776
 777         err = -EPIPE;
 778         if (sk->sk_err)
 779                 goto out_error;
 780
 781         if (kcm->seq_skb) {
 782                 /* Previously opened message */
 783                 head = kcm->seq_skb;
 784                 skb = kcm_tx_msg(head)->last_skb;
 785                 i = skb_shinfo(skb)->nr_frags;
 786
 787                 if (skb_can_coalesce(skb, i, page, offset)) {
 788                         skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
 789                         skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
 790                         goto coalesced;
 791                 }
 792
 793                 if (i >= MAX_SKB_FRAGS) {
 794                         struct sk_buff *tskb;
 795
 796                         tskb = alloc_skb(0, sk->sk_allocation);
 797                         while (!tskb) {
 798                                 kcm_push(kcm);
 799                                 err = sk_stream_wait_memory(sk, &timeo);
 800                                 if (err)
 801                                         goto out_error;
 802                         }
 803
 804                         if (head == skb)
 805                                 skb_shinfo(head)->frag_list = tskb;
 806                         else
 807                                 skb->next = tskb;
 808
 809                         skb = tskb;
 810                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 811                         i = 0;
 812                 }
 813         } else {
 814                 /* Call the sk_stream functions to manage the sndbuf mem. */
 815                 if (!sk_stream_memory_free(sk)) {
 816                         kcm_push(kcm);
 817                         set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 818                         err = sk_stream_wait_memory(sk, &timeo);
 819                         if (err)
 820                                 goto out_error;
 821                 }
 822
 823                 head = alloc_skb(0, sk->sk_allocation);
 824                 while (!head) {
 825                         kcm_push(kcm);
 826                         err = sk_stream_wait_memory(sk, &timeo);
 827                         if (err)
 828                                 goto out_error;
 829                 }
 830
 831                 skb = head;
 832                 i = 0;
 833         }
 834
 835         get_page(page);
 836         skb_fill_page_desc(skb, i, page, offset, size);
 837         skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
 838
 839 coalesced:
 840         skb->len += size;
 841         skb->data_len += size;
 842         skb->truesize += size;
 843         sk->sk_wmem_queued += size;
 844         sk_mem_charge(sk, size);
 845
 846         if (head != skb) {
 847                 head->len += size;
 848                 head->data_len += size;
 849                 head->truesize += size;
 850         }
 851
 852         if (eor) {
 853                 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
 854
 855                 /* Message complete, queue it on send buffer */
 856                 __skb_queue_tail(&sk->sk_write_queue, head);
 857                 kcm->seq_skb = NULL;
 858                 KCM_STATS_INCR(kcm->stats.tx_msgs);
 859
 860                 if (flags & MSG_BATCH) {
 861                         kcm->tx_wait_more = true;
 862                 } else if (kcm->tx_wait_more || not_busy) {
 863                         err = kcm_write_msgs(kcm);
 864                         if (err < 0) {
 865                                 /* We got a hard error in write_msgs but have
 866                                  * already queued this message. Report an error
 867                                  * in the socket, but don't affect return value
 868                                  * from sendmsg
 869                                  */
 870                                 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
 871                                 report_csk_error(&kcm->sk, -err);
 872                         }
 873                 }
 874         } else {
 875                 /* Message not complete, save state */
 876                 kcm->seq_skb = head;
 877                 kcm_tx_msg(head)->last_skb = skb;
 878         }
 879
 880         KCM_STATS_ADD(kcm->stats.tx_bytes, size);
 881
 882         release_sock(sk);
 883         return size;
 884
 885 out_error:
 886         kcm_push(kcm);
 887
 888         err = sk_stream_error(sk, flags, err);
 889
 890         /* make sure we wake any epoll edge trigger waiter */
 891         if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
 892                 sk->sk_write_space(sk);
 893
 894         release_sock(sk);
 895         return err;
 896 }
 897
 898 static int kcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 899 {
 900         struct sock *sk = sock->sk;
 901         struct kcm_sock *kcm = kcm_sk(sk);
 902         struct sk_buff *skb = NULL, *head = NULL;
 903         size_t copy, copied = 0;
 904         long timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
 905         int eor = (sock->type == SOCK_DGRAM) ?
 906                   !(msg->msg_flags & MSG_MORE) : !!(msg->msg_flags & MSG_EOR);
 907         int err = -EPIPE;
 908
 909         lock_sock(sk);
 910
 911         /* Per tcp_sendmsg this should be in poll */
 912         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 913
 914         if (sk->sk_err)
 915                 goto out_error;
 916
 917         if (kcm->seq_skb) {
 918                 /* Previously opened message */
 919                 head = kcm->seq_skb;
 920                 skb = kcm_tx_msg(head)->last_skb;
 921                 goto start;
 922         }
 923
 924         /* Call the sk_stream functions to manage the sndbuf mem. */
 925         if (!sk_stream_memory_free(sk)) {
 926                 kcm_push(kcm);
 927                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 928                 err = sk_stream_wait_memory(sk, &timeo);
 929                 if (err)
 930                         goto out_error;
 931         }
 932
 933         if (msg_data_left(msg)) {
 934                 /* New message, alloc head skb */
 935                 head = alloc_skb(0, sk->sk_allocation);
 936                 while (!head) {
 937                         kcm_push(kcm);
 938                         err = sk_stream_wait_memory(sk, &timeo);
 939                         if (err)
 940                                 goto out_error;
 941
 942                         head = alloc_skb(0, sk->sk_allocation);
 943                 }
 944
 945                 skb = head;
 946
 947                 /* Set ip_summed to CHECKSUM_UNNECESSARY to avoid calling
 948                  * csum_and_copy_from_iter from skb_do_copy_data_nocache.
 949                  */
 950                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 951         }
 952
 953 start:
 954         while (msg_data_left(msg)) {
 955                 bool merge = true;
 956                 int i = skb_shinfo(skb)->nr_frags;
 957                 struct page_frag *pfrag = sk_page_frag(sk);
 958
 959                 if (!sk_page_frag_refill(sk, pfrag))
 960                         goto wait_for_memory;
 961
 962                 if (!skb_can_coalesce(skb, i, pfrag->page,
 963                                       pfrag->offset)) {
 964                         if (i == MAX_SKB_FRAGS) {
 965                                 struct sk_buff *tskb;
 966
 967                                 tskb = alloc_skb(0, sk->sk_allocation);
 968                                 if (!tskb)
 969                                         goto wait_for_memory;
 970
 971                                 if (head == skb)
 972                                         skb_shinfo(head)->frag_list = tskb;
 973                                 else
 974                                         skb->next = tskb;
 975
 976                                 skb = tskb;
 977                                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 978                                 continue;
 979                         }
 980                         merge = false;
 981                 }
 982
 983                 copy = min_t(int, msg_data_left(msg),
 984                              pfrag->size - pfrag->offset);
 985
 986                 if (!sk_wmem_schedule(sk, copy))
 987                         goto wait_for_memory;
 988
 989                 err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
 990                                                pfrag->page,
 991                                                pfrag->offset,
 992                                                copy);
 993                 if (err)
 994                         goto out_error;
 995
 996                 /* Update the skb. */
 997                 if (merge) {
 998                         skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
 999                 } else {
1000                         skb_fill_page_desc(skb, i, pfrag->page,
1001                                            pfrag->offset, copy);
1002                         get_page(pfrag->page);
1003                 }
1004
1005                 pfrag->offset += copy;
1006                 copied += copy;
1007                 if (head != skb) {
1008                         head->len += copy;
1009                         head->data_len += copy;
1010                 }
1011
1012                 continue;
1013
1014 wait_for_memory:
1015                 kcm_push(kcm);
1016                 err = sk_stream_wait_memory(sk, &timeo);
1017                 if (err)
1018                         goto out_error;
1019         }
1020
1021         if (eor) {
1022                 bool not_busy = skb_queue_empty(&sk->sk_write_queue);
1023
1024                 if (head) {
1025                         /* Message complete, queue it on send buffer */
1026                         __skb_queue_tail(&sk->sk_write_queue, head);
1027                         kcm->seq_skb = NULL;
1028                         KCM_STATS_INCR(kcm->stats.tx_msgs);
1029                 }
1030
1031                 if (msg->msg_flags & MSG_BATCH) {
1032                         kcm->tx_wait_more = true;
1033                 } else if (kcm->tx_wait_more || not_busy) {
1034                         err = kcm_write_msgs(kcm);
1035                         if (err < 0) {
1036                                 /* We got a hard error in write_msgs but have
1037                                  * already queued this message. Report an error
1038                                  * in the socket, but don't affect return value
1039                                  * from sendmsg
1040                                  */
1041                                 pr_warn("KCM: Hard failure on kcm_write_msgs\n");
1042                                 report_csk_error(&kcm->sk, -err);
1043                         }
1044                 }
1045         } else {
1046                 /* Message not complete, save state */
1047 partial_message:
1048                 if (head) {
1049                         kcm->seq_skb = head;
1050                         kcm_tx_msg(head)->last_skb = skb;
1051                 }
1052         }
1053
1054         KCM_STATS_ADD(kcm->stats.tx_bytes, copied);
1055
1056         release_sock(sk);
1057         return copied;
1058
1059 out_error:
1060         kcm_push(kcm);
1061
1062         if (copied && sock->type == SOCK_SEQPACKET) {
1063                 /* Wrote some bytes before encountering an
1064                  * error, return partial success.
1065                  */
1066                 goto partial_message;
1067         }
1068
1069         if (head != kcm->seq_skb)
1070                 kfree_skb(head);
1071
1072         err = sk_stream_error(sk, msg->msg_flags, err);
1073
1074         /* make sure we wake any epoll edge trigger waiter */
1075         if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
1076                 sk->sk_write_space(sk);
1077
1078         release_sock(sk);
1079         return err;
1080 }
1081
1082 static struct sk_buff *kcm_wait_data(struct sock *sk, int flags,
1083                                      long timeo, int *err)
1084 {
1085         struct sk_buff *skb;
1086
1087         while (!(skb = skb_peek(&sk->sk_receive_queue))) {
1088                 if (sk->sk_err) {
1089                         *err = sock_error(sk);
1090                         return NULL;
1091                 }
1092
1093                 if (sock_flag(sk, SOCK_DONE))
1094                         return NULL;
1095
1096                 if ((flags & MSG_DONTWAIT) || !timeo) {
1097                         *err = -EAGAIN;
1098                         return NULL;
1099                 }
1100
1101                 sk_wait_data(sk, &timeo, NULL);
1102
1103                 /* Handle signals */
1104                 if (signal_pending(current)) {
1105                         *err = sock_intr_errno(timeo);
1106                         return NULL;
1107                 }
1108         }
1109
1110         return skb;
1111 }
1112
1113 static int kcm_recvmsg(struct socket *sock, struct msghdr *msg,
1114                        size_t len, int flags)
1115 {
1116         struct sock *sk = sock->sk;
1117         struct kcm_sock *kcm = kcm_sk(sk);
1118         int err = 0;
1119         long timeo;
1120         struct strp_msg *stm;
1121         int copied = 0;
1122         struct sk_buff *skb;
1123
1124         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
1125
1126         lock_sock(sk);
1127
1128         skb = kcm_wait_data(sk, flags, timeo, &err);
1129         if (!skb)
1130                 goto out;
1131
1132         /* Okay, have a message on the receive queue */
1133
1134         stm = strp_msg(skb);
1135
1136         if (len > stm->full_len)
1137                 len = stm->full_len;
1138
1139         err = skb_copy_datagram_msg(skb, stm->offset, msg, len);
1140         if (err < 0)
1141                 goto out;
1142
1143         copied = len;
1144         if (likely(!(flags & MSG_PEEK))) {
1145                 KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1146                 if (copied < stm->full_len) {
1147                         if (sock->type == SOCK_DGRAM) {
1148                                 /* Truncated message */
1149                                 msg->msg_flags |= MSG_TRUNC;
1150                                 goto msg_finished;
1151                         }
1152                         stm->offset += copied;
1153                         stm->full_len -= copied;
1154                 } else {
1155 msg_finished:
1156                         /* Finished with message */
1157                         msg->msg_flags |= MSG_EOR;
1158                         KCM_STATS_INCR(kcm->stats.rx_msgs);
1159                         skb_unlink(skb, &sk->sk_receive_queue);
1160                         kfree_skb(skb);
1161                 }
1162         }
1163
1164 out:
1165         release_sock(sk);
1166
1167         return copied ? : err;
1168 }
1169
1170 static ssize_t kcm_splice_read(struct socket *sock, loff_t *ppos,
1171                                struct pipe_inode_info *pipe, size_t len,
1172                                unsigned int flags)
1173 {
1174         struct sock *sk = sock->sk;
1175         struct kcm_sock *kcm = kcm_sk(sk);
1176         long timeo;
1177         struct strp_msg *stm;
1178         int err = 0;
1179         ssize_t copied;
1180         struct sk_buff *skb;
1181
1182         /* Only support splice for SOCKSEQPACKET */
1183
1184         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
1185
1186         lock_sock(sk);
1187
1188         skb = kcm_wait_data(sk, flags, timeo, &err);
1189         if (!skb)
1190                 goto err_out;
1191
1192         /* Okay, have a message on the receive queue */
1193
1194         stm = strp_msg(skb);
1195
1196         if (len > stm->full_len)
1197                 len = stm->full_len;
1198
1199         copied = skb_splice_bits(skb, sk, stm->offset, pipe, len, flags);
1200         if (copied < 0) {
1201                 err = copied;
1202                 goto err_out;
1203         }
1204
1205         KCM_STATS_ADD(kcm->stats.rx_bytes, copied);
1206
1207         stm->offset += copied;
1208         stm->full_len -= copied;
1209
1210         /* We have no way to return MSG_EOR. If all the bytes have been
1211          * read we still leave the message in the receive socket buffer.
1212          * A subsequent recvmsg needs to be done to return MSG_EOR and
1213          * finish reading the message.
1214          */
1215
1216         release_sock(sk);
1217
1218         return copied;
1219
1220 err_out:
1221         release_sock(sk);
1222
1223         return err;
1224 }
1225
1226 /* kcm sock lock held */
1227 static void kcm_recv_disable(struct kcm_sock *kcm)
1228 {
1229         struct kcm_mux *mux = kcm->mux;
1230
1231         if (kcm->rx_disabled)
1232                 return;
1233
1234         spin_lock_bh(&mux->rx_lock);
1235
1236         kcm->rx_disabled = 1;
1237
1238         /* If a psock is reserved we'll do cleanup in unreserve */
1239         if (!kcm->rx_psock) {
1240                 if (kcm->rx_wait) {
1241                         list_del(&kcm->wait_rx_list);
1242                         kcm->rx_wait = false;
1243                 }
1244
1245                 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue);
1246         }
1247
1248         spin_unlock_bh(&mux->rx_lock);
1249 }
1250
1251 /* kcm sock lock held */
1252 static void kcm_recv_enable(struct kcm_sock *kcm)
1253 {
1254         struct kcm_mux *mux = kcm->mux;
1255
1256         if (!kcm->rx_disabled)
1257                 return;
1258
1259         spin_lock_bh(&mux->rx_lock);
1260
1261         kcm->rx_disabled = 0;
1262         kcm_rcv_ready(kcm);
1263
1264         spin_unlock_bh(&mux->rx_lock);
1265 }
1266
1267 static int kcm_setsockopt(struct socket *sock, int level, int optname,
1268                           sockptr_t optval, unsigned int optlen)
1269 {
1270         struct kcm_sock *kcm = kcm_sk(sock->sk);
1271         int val, valbool;
1272         int err = 0;
1273
1274         if (level != SOL_KCM)
1275                 return -ENOPROTOOPT;
1276
1277         if (optlen < sizeof(int))
1278                 return -EINVAL;
1279
1280         if (copy_from_sockptr(&val, optval, sizeof(int)))
1281                 return -EFAULT;
1282
1283         valbool = val ? 1 : 0;
1284
1285         switch (optname) {
1286         case KCM_RECV_DISABLE:
1287                 lock_sock(&kcm->sk);
1288                 if (valbool)
1289                         kcm_recv_disable(kcm);
1290                 else
1291                         kcm_recv_enable(kcm);
1292                 release_sock(&kcm->sk);
1293                 break;
1294         default:
1295                 err = -ENOPROTOOPT;
1296         }
1297
1298         return err;
1299 }
1300
1301 static int kcm_getsockopt(struct socket *sock, int level, int optname,
1302                           char __user *optval, int __user *optlen)
1303 {
1304         struct kcm_sock *kcm = kcm_sk(sock->sk);
1305         int val, len;
1306
1307         if (level != SOL_KCM)
1308                 return -ENOPROTOOPT;
1309
1310         if (get_user(len, optlen))
1311                 return -EFAULT;
1312
1313         len = min_t(unsigned int, len, sizeof(int));
1314         if (len < 0)
1315                 return -EINVAL;
1316
1317         switch (optname) {
1318         case KCM_RECV_DISABLE:
1319                 val = kcm->rx_disabled;
1320                 break;
1321         default:
1322                 return -ENOPROTOOPT;
1323         }
1324
1325         if (put_user(len, optlen))
1326                 return -EFAULT;
1327         if (copy_to_user(optval, &val, len))
1328                 return -EFAULT;
1329         return 0;
1330 }
1331
1332 static void init_kcm_sock(struct kcm_sock *kcm, struct kcm_mux *mux)
1333 {
1334         struct kcm_sock *tkcm;
1335         struct list_head *head;
1336         int index = 0;
1337
1338         /* For SOCK_SEQPACKET sock type, datagram_poll checks the sk_state, so
1339          * we set sk_state, otherwise epoll_wait always returns right away with
1340          * EPOLLHUP
1341          */
1342         kcm->sk.sk_state = TCP_ESTABLISHED;
1343
1344         /* Add to mux's kcm sockets list */
1345         kcm->mux = mux;
1346         spin_lock_bh(&mux->lock);
1347
1348         head = &mux->kcm_socks;
1349         list_for_each_entry(tkcm, &mux->kcm_socks, kcm_sock_list) {
1350                 if (tkcm->index != index)
1351                         break;
1352                 head = &tkcm->kcm_sock_list;
1353                 index++;
1354         }
1355
1356         list_add(&kcm->kcm_sock_list, head);
1357         kcm->index = index;
1358
1359         mux->kcm_socks_cnt++;
1360         spin_unlock_bh(&mux->lock);
1361
1362         INIT_WORK(&kcm->tx_work, kcm_tx_work);
1363
1364         spin_lock_bh(&mux->rx_lock);
1365         kcm_rcv_ready(kcm);
1366         spin_unlock_bh(&mux->rx_lock);
1367 }
1368
1369 static int kcm_attach(struct socket *sock, struct socket *csock,
1370                       struct bpf_prog *prog)
1371 {
1372         struct kcm_sock *kcm = kcm_sk(sock->sk);
1373         struct kcm_mux *mux = kcm->mux;
1374         struct sock *csk;
1375         struct kcm_psock *psock = NULL, *tpsock;
1376         struct list_head *head;
1377         int index = 0;
1378         static const struct strp_callbacks cb = {
1379                 .rcv_msg = kcm_rcv_strparser,
1380                 .parse_msg = kcm_parse_func_strparser,
1381                 .read_sock_done = kcm_read_sock_done,
1382         };
1383         int err = 0;
1384
1385         csk = csock->sk;
1386         if (!csk)
1387                 return -EINVAL;
1388
1389         lock_sock(csk);
1390
1391         /* Only allow TCP sockets to be attached for now */
1392         if ((csk->sk_family != AF_INET && csk->sk_family != AF_INET6) ||
1393             csk->sk_protocol != IPPROTO_TCP) {
1394                 err = -EOPNOTSUPP;
1395                 goto out;
1396         }
1397
1398         /* Don't allow listeners or closed sockets */
1399         if (csk->sk_state == TCP_LISTEN || csk->sk_state == TCP_CLOSE) {
1400                 err = -EOPNOTSUPP;
1401                 goto out;
1402         }
1403
1404         psock = kmem_cache_zalloc(kcm_psockp, GFP_KERNEL);
1405         if (!psock) {
1406                 err = -ENOMEM;
1407                 goto out;
1408         }
1409
1410         psock->mux = mux;
1411         psock->sk = csk;
1412         psock->bpf_prog = prog;
1413
1414         err = strp_init(&psock->strp, csk, &cb);
1415         if (err) {
1416                 kmem_cache_free(kcm_psockp, psock);
1417                 goto out;
1418         }
1419
1420         write_lock_bh(&csk->sk_callback_lock);
1421
1422         /* Check if sk_user_data is aready by KCM or someone else.
1423          * Must be done under lock to prevent race conditions.
1424          */
1425         if (csk->sk_user_data) {
1426                 write_unlock_bh(&csk->sk_callback_lock);
1427                 strp_stop(&psock->strp);
1428                 strp_done(&psock->strp);
1429                 kmem_cache_free(kcm_psockp, psock);
1430                 err = -EALREADY;
1431                 goto out;
1432         }
1433
1434         psock->save_data_ready = csk->sk_data_ready;
1435         psock->save_write_space = csk->sk_write_space;
1436         psock->save_state_change = csk->sk_state_change;
1437         csk->sk_user_data = psock;
1438         csk->sk_data_ready = psock_data_ready;
1439         csk->sk_write_space = psock_write_space;
1440         csk->sk_state_change = psock_state_change;
1441
1442         write_unlock_bh(&csk->sk_callback_lock);
1443
1444         sock_hold(csk);
1445
1446         /* Finished initialization, now add the psock to the MUX. */
1447         spin_lock_bh(&mux->lock);
1448         head = &mux->psocks;
1449         list_for_each_entry(tpsock, &mux->psocks, psock_list) {
1450                 if (tpsock->index != index)
1451                         break;
1452                 head = &tpsock->psock_list;
1453                 index++;
1454         }
1455
1456         list_add(&psock->psock_list, head);
1457         psock->index = index;
1458
1459         KCM_STATS_INCR(mux->stats.psock_attach);
1460         mux->psocks_cnt++;
1461         psock_now_avail(psock);
1462         spin_unlock_bh(&mux->lock);
1463
1464         /* Schedule RX work in case there are already bytes queued */
1465         strp_check_rcv(&psock->strp);
1466
1467 out:
1468         release_sock(csk);
1469
1470         return err;
1471 }
1472
1473 static int kcm_attach_ioctl(struct socket *sock, struct kcm_attach *info)
1474 {
1475         struct socket *csock;
1476         struct bpf_prog *prog;
1477         int err;
1478
1479         csock = sockfd_lookup(info->fd, &err);
1480         if (!csock)
1481                 return -ENOENT;
1482
1483         prog = bpf_prog_get_type(info->bpf_fd, BPF_PROG_TYPE_SOCKET_FILTER);
1484         if (IS_ERR(prog)) {
1485                 err = PTR_ERR(prog);
1486                 goto out;
1487         }
1488
1489         err = kcm_attach(sock, csock, prog);
1490         if (err) {
1491                 bpf_prog_put(prog);
1492                 goto out;
1493         }
1494
1495         /* Keep reference on file also */
1496
1497         return 0;
1498 out:
1499         fput(csock->file);
1500         return err;
1501 }
1502
1503 static void kcm_unattach(struct kcm_psock *psock)
1504 {
1505         struct sock *csk = psock->sk;
1506         struct kcm_mux *mux = psock->mux;
1507
1508         lock_sock(csk);
1509
1510         /* Stop getting callbacks from TCP socket. After this there should
1511          * be no way to reserve a kcm for this psock.
1512          */
1513         write_lock_bh(&csk->sk_callback_lock);
1514         csk->sk_user_data = NULL;
1515         csk->sk_data_ready = psock->save_data_ready;
1516         csk->sk_write_space = psock->save_write_space;
1517         csk->sk_state_change = psock->save_state_change;
1518         strp_stop(&psock->strp);
1519
1520         if (WARN_ON(psock->rx_kcm)) {
1521                 write_unlock_bh(&csk->sk_callback_lock);
1522                 release_sock(csk);
1523                 return;
1524         }
1525
1526         spin_lock_bh(&mux->rx_lock);
1527
1528         /* Stop receiver activities. After this point psock should not be
1529          * able to get onto ready list either through callbacks or work.
1530          */
1531         if (psock->ready_rx_msg) {
1532                 list_del(&psock->psock_ready_list);
1533                 kfree_skb(psock->ready_rx_msg);
1534                 psock->ready_rx_msg = NULL;
1535                 KCM_STATS_INCR(mux->stats.rx_ready_drops);
1536         }
1537
1538         spin_unlock_bh(&mux->rx_lock);
1539
1540         write_unlock_bh(&csk->sk_callback_lock);
1541
1542         /* Call strp_done without sock lock */
1543         release_sock(csk);
1544         strp_done(&psock->strp);
1545         lock_sock(csk);
1546
1547         bpf_prog_put(psock->bpf_prog);
1548
1549         spin_lock_bh(&mux->lock);
1550
1551         aggregate_psock_stats(&psock->stats, &mux->aggregate_psock_stats);
1552         save_strp_stats(&psock->strp, &mux->aggregate_strp_stats);
1553
1554         KCM_STATS_INCR(mux->stats.psock_unattach);
1555
1556         if (psock->tx_kcm) {
1557                 /* psock was reserved.  Just mark it finished and we will clean
1558                  * up in the kcm paths, we need kcm lock which can not be
1559                  * acquired here.
1560                  */
1561                 KCM_STATS_INCR(mux->stats.psock_unattach_rsvd);
1562                 spin_unlock_bh(&mux->lock);
1563
1564                 /* We are unattaching a socket that is reserved. Abort the
1565                  * socket since we may be out of sync in sending on it. We need
1566                  * to do this without the mux lock.
1567                  */
1568                 kcm_abort_tx_psock(psock, EPIPE, false);
1569
1570                 spin_lock_bh(&mux->lock);
1571                 if (!psock->tx_kcm) {
1572                         /* psock now unreserved in window mux was unlocked */
1573                         goto no_reserved;
1574                 }
1575                 psock->done = 1;
1576
1577                 /* Commit done before queuing work to process it */
1578                 smp_mb();
1579
1580                 /* Queue tx work to make sure psock->done is handled */
1581                 queue_work(kcm_wq, &psock->tx_kcm->tx_work);
1582                 spin_unlock_bh(&mux->lock);
1583         } else {
1584 no_reserved:
1585                 if (!psock->tx_stopped)
1586                         list_del(&psock->psock_avail_list);
1587                 list_del(&psock->psock_list);
1588                 mux->psocks_cnt--;
1589                 spin_unlock_bh(&mux->lock);
1590
1591                 sock_put(csk);
1592                 fput(csk->sk_socket->file);
1593                 kmem_cache_free(kcm_psockp, psock);
1594         }
1595
1596         release_sock(csk);
1597 }
1598
1599 static int kcm_unattach_ioctl(struct socket *sock, struct kcm_unattach *info)
1600 {
1601         struct kcm_sock *kcm = kcm_sk(sock->sk);
1602         struct kcm_mux *mux = kcm->mux;
1603         struct kcm_psock *psock;
1604         struct socket *csock;
1605         struct sock *csk;
1606         int err;
1607
1608         csock = sockfd_lookup(info->fd, &err);
1609         if (!csock)
1610                 return -ENOENT;
1611
1612         csk = csock->sk;
1613         if (!csk) {
1614                 err = -EINVAL;
1615                 goto out;
1616         }
1617
1618         err = -ENOENT;
1619
1620         spin_lock_bh(&mux->lock);
1621
1622         list_for_each_entry(psock, &mux->psocks, psock_list) {
1623                 if (psock->sk != csk)
1624                         continue;
1625
1626                 /* Found the matching psock */
1627
1628                 if (psock->unattaching || WARN_ON(psock->done)) {
1629                         err = -EALREADY;
1630                         break;
1631                 }
1632
1633                 psock->unattaching = 1;
1634
1635                 spin_unlock_bh(&mux->lock);
1636
1637                 /* Lower socket lock should already be held */
1638                 kcm_unattach(psock);
1639
1640                 err = 0;
1641                 goto out;
1642         }
1643
1644         spin_unlock_bh(&mux->lock);
1645
1646 out:
1647         fput(csock->file);
1648         return err;
1649 }
1650
1651 static struct proto kcm_proto = {
1652         .name   = "KCM",
1653         .owner  = THIS_MODULE,
1654         .obj_size = sizeof(struct kcm_sock),
1655 };
1656
1657 /* Clone a kcm socket. */
1658 static struct file *kcm_clone(struct socket *osock)
1659 {
1660         struct socket *newsock;
1661         struct sock *newsk;
1662
1663         newsock = sock_alloc();
1664         if (!newsock)
1665                 return ERR_PTR(-ENFILE);
1666
1667         newsock->type = osock->type;
1668         newsock->ops = osock->ops;
1669
1670         __module_get(newsock->ops->owner);
1671
1672         newsk = sk_alloc(sock_net(osock->sk), PF_KCM, GFP_KERNEL,
1673                          &kcm_proto, false);
1674         if (!newsk) {
1675                 sock_release(newsock);
1676                 return ERR_PTR(-ENOMEM);
1677         }
1678         sock_init_data(newsock, newsk);
1679         init_kcm_sock(kcm_sk(newsk), kcm_sk(osock->sk)->mux);
1680
1681         return sock_alloc_file(newsock, 0, osock->sk->sk_prot_creator->name);
1682 }
1683
1684 static int kcm_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
1685 {
1686         int err;
1687
1688         switch (cmd) {
1689         case SIOCKCMATTACH: {
1690                 struct kcm_attach info;
1691
1692                 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1693                         return -EFAULT;
1694
1695                 err = kcm_attach_ioctl(sock, &info);
1696
1697                 break;
1698         }
1699         case SIOCKCMUNATTACH: {
1700                 struct kcm_unattach info;
1701
1702                 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
1703                         return -EFAULT;
1704
1705                 err = kcm_unattach_ioctl(sock, &info);
1706
1707                 break;
1708         }
1709         case SIOCKCMCLONE: {
1710                 struct kcm_clone info;
1711                 struct file *file;
1712
1713                 info.fd = get_unused_fd_flags(0);
1714                 if (unlikely(info.fd < 0))
1715                         return info.fd;
1716
1717                 file = kcm_clone(sock);
1718                 if (IS_ERR(file)) {
1719                         put_unused_fd(info.fd);
1720                         return PTR_ERR(file);
1721                 }
1722                 if (copy_to_user((void __user *)arg, &info,
1723                                  sizeof(info))) {
1724                         put_unused_fd(info.fd);
1725                         fput(file);
1726                         return -EFAULT;
1727                 }
1728                 fd_install(info.fd, file);
1729                 err = 0;
1730                 break;
1731         }
1732         default:
1733                 err = -ENOIOCTLCMD;
1734                 break;
1735         }
1736
1737         return err;
1738 }
1739
1740 static void free_mux(struct rcu_head *rcu)
1741 {
1742         struct kcm_mux *mux = container_of(rcu,
1743             struct kcm_mux, rcu);
1744
1745         kmem_cache_free(kcm_muxp, mux);
1746 }
1747
1748 static void release_mux(struct kcm_mux *mux)
1749 {
1750         struct kcm_net *knet = mux->knet;
1751         struct kcm_psock *psock, *tmp_psock;
1752
1753         /* Release psocks */
1754         list_for_each_entry_safe(psock, tmp_psock,
1755                                  &mux->psocks, psock_list) {
1756                 if (!WARN_ON(psock->unattaching))
1757                         kcm_unattach(psock);
1758         }
1759
1760         if (WARN_ON(mux->psocks_cnt))
1761                 return;
1762
1763         __skb_queue_purge(&mux->rx_hold_queue);
1764
1765         mutex_lock(&knet->mutex);
1766         aggregate_mux_stats(&mux->stats, &knet->aggregate_mux_stats);
1767         aggregate_psock_stats(&mux->aggregate_psock_stats,
1768                               &knet->aggregate_psock_stats);
1769         aggregate_strp_stats(&mux->aggregate_strp_stats,
1770                              &knet->aggregate_strp_stats);
1771         list_del_rcu(&mux->kcm_mux_list);
1772         knet->count--;
1773         mutex_unlock(&knet->mutex);
1774
1775         call_rcu(&mux->rcu, free_mux);
1776 }
1777
1778 static void kcm_done(struct kcm_sock *kcm)
1779 {
1780         struct kcm_mux *mux = kcm->mux;
1781         struct sock *sk = &kcm->sk;
1782         int socks_cnt;
1783
1784         spin_lock_bh(&mux->rx_lock);
1785         if (kcm->rx_psock) {
1786                 /* Cleanup in unreserve_rx_kcm */
1787                 WARN_ON(kcm->done);
1788                 kcm->rx_disabled = 1;
1789                 kcm->done = 1;
1790                 spin_unlock_bh(&mux->rx_lock);
1791                 return;
1792         }
1793
1794         if (kcm->rx_wait) {
1795                 list_del(&kcm->wait_rx_list);
1796                 kcm->rx_wait = false;
1797         }
1798         /* Move any pending receive messages to other kcm sockets */
1799         requeue_rx_msgs(mux, &sk->sk_receive_queue);
1800
1801         spin_unlock_bh(&mux->rx_lock);
1802
1803         if (WARN_ON(sk_rmem_alloc_get(sk)))
1804                 return;
1805
1806         /* Detach from MUX */
1807         spin_lock_bh(&mux->lock);
1808
1809         list_del(&kcm->kcm_sock_list);
1810         mux->kcm_socks_cnt--;
1811         socks_cnt = mux->kcm_socks_cnt;
1812
1813         spin_unlock_bh(&mux->lock);
1814
1815         if (!socks_cnt) {
1816                 /* We are done with the mux now. */
1817                 release_mux(mux);
1818         }
1819
1820         WARN_ON(kcm->rx_wait);
1821
1822         sock_put(&kcm->sk);
1823 }
1824
1825 /* Called by kcm_release to close a KCM socket.
1826  * If this is the last KCM socket on the MUX, destroy the MUX.
1827  */
1828 static int kcm_release(struct socket *sock)
1829 {
1830         struct sock *sk = sock->sk;
1831         struct kcm_sock *kcm;
1832         struct kcm_mux *mux;
1833         struct kcm_psock *psock;
1834
1835         if (!sk)
1836                 return 0;
1837
1838         kcm = kcm_sk(sk);
1839         mux = kcm->mux;
1840
1841         sock_orphan(sk);
1842         kfree_skb(kcm->seq_skb);
1843
1844         lock_sock(sk);
1845         /* Purge queue under lock to avoid race condition with tx_work trying
1846          * to act when queue is nonempty. If tx_work runs after this point
1847          * it will just return.
1848          */
1849         __skb_queue_purge(&sk->sk_write_queue);
1850
1851         /* Set tx_stopped. This is checked when psock is bound to a kcm and we
1852          * get a writespace callback. This prevents further work being queued
1853          * from the callback (unbinding the psock occurs after canceling work.
1854          */
1855         kcm->tx_stopped = 1;
1856
1857         release_sock(sk);
1858
1859         spin_lock_bh(&mux->lock);
1860         if (kcm->tx_wait) {
1861                 /* Take of tx_wait list, after this point there should be no way
1862                  * that a psock will be assigned to this kcm.
1863                  */
1864                 list_del(&kcm->wait_psock_list);
1865                 kcm->tx_wait = false;
1866         }
1867         spin_unlock_bh(&mux->lock);
1868
1869         /* Cancel work. After this point there should be no outside references
1870          * to the kcm socket.
1871          */
1872         cancel_work_sync(&kcm->tx_work);
1873
1874         lock_sock(sk);
1875         psock = kcm->tx_psock;
1876         if (psock) {
1877                 /* A psock was reserved, so we need to kill it since it
1878                  * may already have some bytes queued from a message. We
1879                  * need to do this after removing kcm from tx_wait list.
1880                  */
1881                 kcm_abort_tx_psock(psock, EPIPE, false);
1882                 unreserve_psock(kcm);
1883         }
1884         release_sock(sk);
1885
1886         WARN_ON(kcm->tx_wait);
1887         WARN_ON(kcm->tx_psock);
1888
1889         sock->sk = NULL;
1890
1891         kcm_done(kcm);
1892
1893         return 0;
1894 }
1895
1896 static const struct proto_ops kcm_dgram_ops = {
1897         .family =       PF_KCM,
1898         .owner =        THIS_MODULE,
1899         .release =      kcm_release,
1900         .bind =         sock_no_bind,
1901         .connect =      sock_no_connect,
1902         .socketpair =   sock_no_socketpair,
1903         .accept =       sock_no_accept,
1904         .getname =      sock_no_getname,
1905         .poll =         datagram_poll,
1906         .ioctl =        kcm_ioctl,
1907         .listen =       sock_no_listen,
1908         .shutdown =     sock_no_shutdown,
1909         .setsockopt =   kcm_setsockopt,
1910         .getsockopt =   kcm_getsockopt,
1911         .sendmsg =      kcm_sendmsg,
1912         .recvmsg =      kcm_recvmsg,
1913         .mmap =         sock_no_mmap,
1914         .sendpage =     kcm_sendpage,
1915 };
1916
1917 static const struct proto_ops kcm_seqpacket_ops = {
1918         .family =       PF_KCM,
1919         .owner =        THIS_MODULE,
1920         .release =      kcm_release,
1921         .bind =         sock_no_bind,
1922         .connect =      sock_no_connect,
1923         .socketpair =   sock_no_socketpair,
1924         .accept =       sock_no_accept,
1925         .getname =      sock_no_getname,
1926         .poll =         datagram_poll,
1927         .ioctl =        kcm_ioctl,
1928         .listen =       sock_no_listen,
1929         .shutdown =     sock_no_shutdown,
1930         .setsockopt =   kcm_setsockopt,
1931         .getsockopt =   kcm_getsockopt,
1932         .sendmsg =      kcm_sendmsg,
1933         .recvmsg =      kcm_recvmsg,
1934         .mmap =         sock_no_mmap,
1935         .sendpage =     kcm_sendpage,
1936         .splice_read =  kcm_splice_read,
1937 };
1938
1939 /* Create proto operation for kcm sockets */
1940 static int kcm_create(struct net *net, struct socket *sock,
1941                       int protocol, int kern)
1942 {
1943         struct kcm_net *knet = net_generic(net, kcm_net_id);
1944         struct sock *sk;
1945         struct kcm_mux *mux;
1946
1947         switch (sock->type) {
1948         case SOCK_DGRAM:
1949                 sock->ops = &kcm_dgram_ops;
1950                 break;
1951         case SOCK_SEQPACKET:
1952                 sock->ops = &kcm_seqpacket_ops;
1953                 break;
1954         default:
1955                 return -ESOCKTNOSUPPORT;
1956         }
1957
1958         if (protocol != KCMPROTO_CONNECTED)
1959                 return -EPROTONOSUPPORT;
1960
1961         sk = sk_alloc(net, PF_KCM, GFP_KERNEL, &kcm_proto, kern);
1962         if (!sk)
1963                 return -ENOMEM;
1964
1965         /* Allocate a kcm mux, shared between KCM sockets */
1966         mux = kmem_cache_zalloc(kcm_muxp, GFP_KERNEL);
1967         if (!mux) {
1968                 sk_free(sk);
1969                 return -ENOMEM;
1970         }
1971
1972         spin_lock_init(&mux->lock);
1973         spin_lock_init(&mux->rx_lock);
1974         INIT_LIST_HEAD(&mux->kcm_socks);
1975         INIT_LIST_HEAD(&mux->kcm_rx_waiters);
1976         INIT_LIST_HEAD(&mux->kcm_tx_waiters);
1977
1978         INIT_LIST_HEAD(&mux->psocks);
1979         INIT_LIST_HEAD(&mux->psocks_ready);
1980         INIT_LIST_HEAD(&mux->psocks_avail);
1981
1982         mux->knet = knet;
1983
1984         /* Add new MUX to list */
1985         mutex_lock(&knet->mutex);
1986         list_add_rcu(&mux->kcm_mux_list, &knet->mux_list);
1987         knet->count++;
1988         mutex_unlock(&knet->mutex);
1989
1990         skb_queue_head_init(&mux->rx_hold_queue);
1991
1992         /* Init KCM socket */
1993         sock_init_data(sock, sk);
1994         init_kcm_sock(kcm_sk(sk), mux);
1995
1996         return 0;
1997 }
1998
1999 static const struct net_proto_family kcm_family_ops = {
2000         .family = PF_KCM,
2001         .create = kcm_create,
2002         .owner  = THIS_MODULE,
2003 };
2004
2005 static __net_init int kcm_init_net(struct net *net)
2006 {
2007         struct kcm_net *knet = net_generic(net, kcm_net_id);
2008
2009         INIT_LIST_HEAD_RCU(&knet->mux_list);
2010         mutex_init(&knet->mutex);
2011
2012         return 0;
2013 }
2014
2015 static __net_exit void kcm_exit_net(struct net *net)
2016 {
2017         struct kcm_net *knet = net_generic(net, kcm_net_id);
2018
2019         /* All KCM sockets should be closed at this point, which should mean
2020          * that all multiplexors and psocks have been destroyed.
2021          */
2022         WARN_ON(!list_empty(&knet->mux_list));
2023 }
2024
2025 static struct pernet_operations kcm_net_ops = {
2026         .init = kcm_init_net,
2027         .exit = kcm_exit_net,
2028         .id   = &kcm_net_id,
2029         .size = sizeof(struct kcm_net),
2030 };
2031
2032 static int __init kcm_init(void)
2033 {
2034         int err = -ENOMEM;
2035
2036         kcm_muxp = kmem_cache_create("kcm_mux_cache",
2037                                      sizeof(struct kcm_mux), 0,
2038                                      SLAB_HWCACHE_ALIGN, NULL);
2039         if (!kcm_muxp)
2040                 goto fail;
2041
2042         kcm_psockp = kmem_cache_create("kcm_psock_cache",
2043                                        sizeof(struct kcm_psock), 0,
2044                                         SLAB_HWCACHE_ALIGN, NULL);
2045         if (!kcm_psockp)
2046                 goto fail;
2047
2048         kcm_wq = create_singlethread_workqueue("kkcmd");
2049         if (!kcm_wq)
2050                 goto fail;
2051
2052         err = proto_register(&kcm_proto, 1);
2053         if (err)
2054                 goto fail;
2055
2056         err = register_pernet_device(&kcm_net_ops);
2057         if (err)
2058                 goto net_ops_fail;
2059
2060         err = sock_register(&kcm_family_ops);
2061         if (err)
2062                 goto sock_register_fail;
2063
2064         err = kcm_proc_init();
2065         if (err)
2066                 goto proc_init_fail;
2067
2068         return 0;
2069
2070 proc_init_fail:
2071         sock_unregister(PF_KCM);
2072
2073 sock_register_fail:
2074         unregister_pernet_device(&kcm_net_ops);
2075
2076 net_ops_fail:
2077         proto_unregister(&kcm_proto);
2078
2079 fail:
2080         kmem_cache_destroy(kcm_muxp);
2081         kmem_cache_destroy(kcm_psockp);
2082
2083         if (kcm_wq)
2084                 destroy_workqueue(kcm_wq);
2085
2086         return err;
2087 }
2088
2089 static void __exit kcm_exit(void)
2090 {
2091         kcm_proc_exit();
2092         sock_unregister(PF_KCM);
2093         unregister_pernet_device(&kcm_net_ops);
2094         proto_unregister(&kcm_proto);
2095         destroy_workqueue(kcm_wq);
2096
2097         kmem_cache_destroy(kcm_muxp);
2098         kmem_cache_destroy(kcm_psockp);
2099 }
2100
2101 module_init(kcm_init);
2102 module_exit(kcm_exit);
2103
2104 MODULE_LICENSE("GPL");
2105 MODULE_ALIAS_NETPROTO(PF_KCM);