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