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 struct sock *sk = &kcm->sk; 585 struct kcm_psock *psock; 586 struct sk_buff *skb, *head; 587 struct kcm_tx_msg *txm; 588 unsigned short fragidx, frag_offset; 589 unsigned int sent, total_sent = 0; 590 int ret = 0; 591 592 kcm->tx_wait_more = false; 593 psock = kcm->tx_psock; 594 if (unlikely(psock && psock->tx_stopped)) { 595 /* A reserved psock was aborted asynchronously. Unreserve 596 * it and we'll retry the message. 597 */ 598 unreserve_psock(kcm); 599 kcm_report_tx_retry(kcm); 600 if (skb_queue_empty(&sk->sk_write_queue)) 601 return 0; 602 603 kcm_tx_msg(skb_peek(&sk->sk_write_queue))->sent = 0; 604 605 } else if (skb_queue_empty(&sk->sk_write_queue)) { 606 return 0; 607 } 608 609 head = skb_peek(&sk->sk_write_queue); 610 txm = kcm_tx_msg(head); 611 612 if (txm->sent) { 613 /* Send of first skbuff in queue already in progress */ 614 if (WARN_ON(!psock)) { 615 ret = -EINVAL; 616 goto out; 617 } 618 sent = txm->sent; 619 frag_offset = txm->frag_offset; 620 fragidx = txm->fragidx; 621 skb = txm->frag_skb; 622 623 goto do_frag; 624 } 625 626 try_again: 627 psock = reserve_psock(kcm); 628 if (!psock) 629 goto out; 630 631 do { 632 skb = head; 633 txm = kcm_tx_msg(head); 634 sent = 0; 635 636 do_frag_list: 637 if (WARN_ON(!skb_shinfo(skb)->nr_frags)) { 638 ret = -EINVAL; 639 goto out; 640 } 641 642 for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags; 643 fragidx++) { 644 struct bio_vec bvec; 645 struct msghdr msg = { 646 .msg_flags = MSG_DONTWAIT | MSG_SPLICE_PAGES, 647 }; 648 skb_frag_t *frag; 649 650 frag_offset = 0; 651 do_frag: 652 frag = &skb_shinfo(skb)->frags[fragidx]; 653 if (WARN_ON(!skb_frag_size(frag))) { 654 ret = -EINVAL; 655 goto out; 656 } 657 658 bvec_set_page(&bvec, 659 skb_frag_page(frag), 660 skb_frag_size(frag) - frag_offset, 661 skb_frag_off(frag) + frag_offset); 662 iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, 663 bvec.bv_len); 664 ret = sock_sendmsg(psock->sk->sk_socket, &msg); 665 if (ret <= 0) { 666 if (ret == -EAGAIN) { 667 /* Save state to try again when there's 668 * write space on the socket 669 */ 670 txm->sent = sent; 671 txm->frag_offset = frag_offset; 672 txm->fragidx = fragidx; 673 txm->frag_skb = skb; 674 675 ret = 0; 676 goto out; 677 } 678 679 /* Hard failure in sending message, abort this 680 * psock since it has lost framing 681 * synchronization and retry sending the 682 * message from the beginning. 683 */ 684 kcm_abort_tx_psock(psock, ret ? -ret : EPIPE, 685 true); 686 unreserve_psock(kcm); 687 688 txm->sent = 0; 689 kcm_report_tx_retry(kcm); 690 ret = 0; 691 692 goto try_again; 693 } 694 695 sent += ret; 696 frag_offset += ret; 697 KCM_STATS_ADD(psock->stats.tx_bytes, ret); 698 if (frag_offset < skb_frag_size(frag)) { 699 /* Not finished with this frag */ 700 goto do_frag; 701 } 702 } 703 704 if (skb == head) { 705 if (skb_has_frag_list(skb)) { 706 skb = skb_shinfo(skb)->frag_list; 707 goto do_frag_list; 708 } 709 } else if (skb->next) { 710 skb = skb->next; 711 goto do_frag_list; 712 } 713 714 /* Successfully sent the whole packet, account for it. */ 715 skb_dequeue(&sk->sk_write_queue); 716 kfree_skb(head); 717 sk->sk_wmem_queued -= sent; 718 total_sent += sent; 719 KCM_STATS_INCR(psock->stats.tx_msgs); 720 } while ((head = skb_peek(&sk->sk_write_queue))); 721 out: 722 if (!head) { 723 /* Done with all queued messages. */ 724 WARN_ON(!skb_queue_empty(&sk->sk_write_queue)); 725 unreserve_psock(kcm); 726 } 727 728 /* Check if write space is available */ 729 sk->sk_write_space(sk); 730 731 return total_sent ? : ret; 732 } 733 734 static void kcm_tx_work(struct work_struct *w) 735 { 736 struct kcm_sock *kcm = container_of(w, struct kcm_sock, tx_work); 737 struct sock *sk = &kcm->sk; 738 int err; 739 740 lock_sock(sk); 741 742 /* Primarily for SOCK_DGRAM sockets, also handle asynchronous tx 743 * aborts 744 */ 745 err = kcm_write_msgs(kcm); 746 if (err < 0) { 747 /* Hard failure in write, report error on KCM socket */ 748 pr_warn("KCM: Hard failure on kcm_write_msgs %d\n", err); 749 report_csk_error(&kcm->sk, -err); 750 goto out; 751 } 752 753 /* Primarily for SOCK_SEQPACKET sockets */ 754 if (likely(sk->sk_socket) && 755 test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { 756 clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags); 757 sk->sk_write_space(sk); 758 } 759 760 out: 761 release_sock(sk); 762 } 763 764 static void kcm_push(struct kcm_sock *kcm) 765 { 766 if (kcm->tx_wait_more) 767 kcm_write_msgs(kcm); 768 } 769 770 static int kcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t len) 771 { 772 struct sock *sk = sock->sk; 773 struct kcm_sock *kcm = kcm_sk(sk); 774 struct sk_buff *skb = NULL, *head = NULL; 775 size_t copy, copied = 0; 776 long timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT); 777 int eor = (sock->type == SOCK_DGRAM) ? 778 !(msg->msg_flags & MSG_MORE) : !!(msg->msg_flags & MSG_EOR); 779 int err = -EPIPE; 780 781 lock_sock(sk); 782 783 /* Per tcp_sendmsg this should be in poll */ 784 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk); 785 786 if (sk->sk_err) 787 goto out_error; 788 789 if (kcm->seq_skb) { 790 /* Previously opened message */ 791 head = kcm->seq_skb; 792 skb = kcm_tx_msg(head)->last_skb; 793 goto start; 794 } 795 796 /* Call the sk_stream functions to manage the sndbuf mem. */ 797 if (!sk_stream_memory_free(sk)) { 798 kcm_push(kcm); 799 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); 800 err = sk_stream_wait_memory(sk, &timeo); 801 if (err) 802 goto out_error; 803 } 804 805 if (msg_data_left(msg)) { 806 /* New message, alloc head skb */ 807 head = alloc_skb(0, sk->sk_allocation); 808 while (!head) { 809 kcm_push(kcm); 810 err = sk_stream_wait_memory(sk, &timeo); 811 if (err) 812 goto out_error; 813 814 head = alloc_skb(0, sk->sk_allocation); 815 } 816 817 skb = head; 818 819 /* Set ip_summed to CHECKSUM_UNNECESSARY to avoid calling 820 * csum_and_copy_from_iter from skb_do_copy_data_nocache. 821 */ 822 skb->ip_summed = CHECKSUM_UNNECESSARY; 823 } 824 825 start: 826 while (msg_data_left(msg)) { 827 bool merge = true; 828 int i = skb_shinfo(skb)->nr_frags; 829 struct page_frag *pfrag = sk_page_frag(sk); 830 831 if (!sk_page_frag_refill(sk, pfrag)) 832 goto wait_for_memory; 833 834 if (!skb_can_coalesce(skb, i, pfrag->page, 835 pfrag->offset)) { 836 if (i == MAX_SKB_FRAGS) { 837 struct sk_buff *tskb; 838 839 tskb = alloc_skb(0, sk->sk_allocation); 840 if (!tskb) 841 goto wait_for_memory; 842 843 if (head == skb) 844 skb_shinfo(head)->frag_list = tskb; 845 else 846 skb->next = tskb; 847 848 skb = tskb; 849 skb->ip_summed = CHECKSUM_UNNECESSARY; 850 continue; 851 } 852 merge = false; 853 } 854 855 if (msg->msg_flags & MSG_SPLICE_PAGES) { 856 copy = msg_data_left(msg); 857 if (!sk_wmem_schedule(sk, copy)) 858 goto wait_for_memory; 859 860 err = skb_splice_from_iter(skb, &msg->msg_iter, copy, 861 sk->sk_allocation); 862 if (err < 0) { 863 if (err == -EMSGSIZE) 864 goto wait_for_memory; 865 goto out_error; 866 } 867 868 copy = err; 869 skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG; 870 sk_wmem_queued_add(sk, copy); 871 sk_mem_charge(sk, copy); 872 873 if (head != skb) 874 head->truesize += copy; 875 } else { 876 copy = min_t(int, msg_data_left(msg), 877 pfrag->size - pfrag->offset); 878 if (!sk_wmem_schedule(sk, copy)) 879 goto wait_for_memory; 880 881 err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb, 882 pfrag->page, 883 pfrag->offset, 884 copy); 885 if (err) 886 goto out_error; 887 888 /* Update the skb. */ 889 if (merge) { 890 skb_frag_size_add( 891 &skb_shinfo(skb)->frags[i - 1], copy); 892 } else { 893 skb_fill_page_desc(skb, i, pfrag->page, 894 pfrag->offset, copy); 895 get_page(pfrag->page); 896 } 897 898 pfrag->offset += copy; 899 } 900 901 copied += copy; 902 if (head != skb) { 903 head->len += copy; 904 head->data_len += copy; 905 } 906 907 continue; 908 909 wait_for_memory: 910 kcm_push(kcm); 911 err = sk_stream_wait_memory(sk, &timeo); 912 if (err) 913 goto out_error; 914 } 915 916 if (eor) { 917 bool not_busy = skb_queue_empty(&sk->sk_write_queue); 918 919 if (head) { 920 /* Message complete, queue it on send buffer */ 921 __skb_queue_tail(&sk->sk_write_queue, head); 922 kcm->seq_skb = NULL; 923 KCM_STATS_INCR(kcm->stats.tx_msgs); 924 } 925 926 if (msg->msg_flags & MSG_BATCH) { 927 kcm->tx_wait_more = true; 928 } else if (kcm->tx_wait_more || not_busy) { 929 err = kcm_write_msgs(kcm); 930 if (err < 0) { 931 /* We got a hard error in write_msgs but have 932 * already queued this message. Report an error 933 * in the socket, but don't affect return value 934 * from sendmsg 935 */ 936 pr_warn("KCM: Hard failure on kcm_write_msgs\n"); 937 report_csk_error(&kcm->sk, -err); 938 } 939 } 940 } else { 941 /* Message not complete, save state */ 942 partial_message: 943 if (head) { 944 kcm->seq_skb = head; 945 kcm_tx_msg(head)->last_skb = skb; 946 } 947 } 948 949 KCM_STATS_ADD(kcm->stats.tx_bytes, copied); 950 951 release_sock(sk); 952 return copied; 953 954 out_error: 955 kcm_push(kcm); 956 957 if (copied && sock->type == SOCK_SEQPACKET) { 958 /* Wrote some bytes before encountering an 959 * error, return partial success. 960 */ 961 goto partial_message; 962 } 963 964 if (head != kcm->seq_skb) 965 kfree_skb(head); 966 967 err = sk_stream_error(sk, msg->msg_flags, err); 968 969 /* make sure we wake any epoll edge trigger waiter */ 970 if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN)) 971 sk->sk_write_space(sk); 972 973 release_sock(sk); 974 return err; 975 } 976 977 static void kcm_splice_eof(struct socket *sock) 978 { 979 struct sock *sk = sock->sk; 980 struct kcm_sock *kcm = kcm_sk(sk); 981 982 if (skb_queue_empty_lockless(&sk->sk_write_queue)) 983 return; 984 985 lock_sock(sk); 986 kcm_write_msgs(kcm); 987 release_sock(sk); 988 } 989 990 static ssize_t kcm_sendpage(struct socket *sock, struct page *page, 991 int offset, size_t size, int flags) 992 993 { 994 struct bio_vec bvec; 995 struct msghdr msg = { .msg_flags = flags | MSG_SPLICE_PAGES, }; 996 997 if (flags & MSG_SENDPAGE_NOTLAST) 998 msg.msg_flags |= MSG_MORE; 999 1000 if (flags & MSG_OOB) 1001 return -EOPNOTSUPP; 1002 1003 bvec_set_page(&bvec, page, size, offset); 1004 iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, size); 1005 return kcm_sendmsg(sock, &msg, size); 1006 } 1007 1008 static int kcm_recvmsg(struct socket *sock, struct msghdr *msg, 1009 size_t len, int flags) 1010 { 1011 struct sock *sk = sock->sk; 1012 struct kcm_sock *kcm = kcm_sk(sk); 1013 int err = 0; 1014 struct strp_msg *stm; 1015 int copied = 0; 1016 struct sk_buff *skb; 1017 1018 skb = skb_recv_datagram(sk, flags, &err); 1019 if (!skb) 1020 goto out; 1021 1022 /* Okay, have a message on the receive queue */ 1023 1024 stm = strp_msg(skb); 1025 1026 if (len > stm->full_len) 1027 len = stm->full_len; 1028 1029 err = skb_copy_datagram_msg(skb, stm->offset, msg, len); 1030 if (err < 0) 1031 goto out; 1032 1033 copied = len; 1034 if (likely(!(flags & MSG_PEEK))) { 1035 KCM_STATS_ADD(kcm->stats.rx_bytes, copied); 1036 if (copied < stm->full_len) { 1037 if (sock->type == SOCK_DGRAM) { 1038 /* Truncated message */ 1039 msg->msg_flags |= MSG_TRUNC; 1040 goto msg_finished; 1041 } 1042 stm->offset += copied; 1043 stm->full_len -= copied; 1044 } else { 1045 msg_finished: 1046 /* Finished with message */ 1047 msg->msg_flags |= MSG_EOR; 1048 KCM_STATS_INCR(kcm->stats.rx_msgs); 1049 } 1050 } 1051 1052 out: 1053 skb_free_datagram(sk, skb); 1054 return copied ? : err; 1055 } 1056 1057 static ssize_t kcm_splice_read(struct socket *sock, loff_t *ppos, 1058 struct pipe_inode_info *pipe, size_t len, 1059 unsigned int flags) 1060 { 1061 struct sock *sk = sock->sk; 1062 struct kcm_sock *kcm = kcm_sk(sk); 1063 struct strp_msg *stm; 1064 int err = 0; 1065 ssize_t copied; 1066 struct sk_buff *skb; 1067 1068 /* Only support splice for SOCKSEQPACKET */ 1069 1070 skb = skb_recv_datagram(sk, flags, &err); 1071 if (!skb) 1072 goto err_out; 1073 1074 /* Okay, have a message on the receive queue */ 1075 1076 stm = strp_msg(skb); 1077 1078 if (len > stm->full_len) 1079 len = stm->full_len; 1080 1081 copied = skb_splice_bits(skb, sk, stm->offset, pipe, len, flags); 1082 if (copied < 0) { 1083 err = copied; 1084 goto err_out; 1085 } 1086 1087 KCM_STATS_ADD(kcm->stats.rx_bytes, copied); 1088 1089 stm->offset += copied; 1090 stm->full_len -= copied; 1091 1092 /* We have no way to return MSG_EOR. If all the bytes have been 1093 * read we still leave the message in the receive socket buffer. 1094 * A subsequent recvmsg needs to be done to return MSG_EOR and 1095 * finish reading the message. 1096 */ 1097 1098 skb_free_datagram(sk, skb); 1099 return copied; 1100 1101 err_out: 1102 skb_free_datagram(sk, skb); 1103 return err; 1104 } 1105 1106 /* kcm sock lock held */ 1107 static void kcm_recv_disable(struct kcm_sock *kcm) 1108 { 1109 struct kcm_mux *mux = kcm->mux; 1110 1111 if (kcm->rx_disabled) 1112 return; 1113 1114 spin_lock_bh(&mux->rx_lock); 1115 1116 kcm->rx_disabled = 1; 1117 1118 /* If a psock is reserved we'll do cleanup in unreserve */ 1119 if (!kcm->rx_psock) { 1120 if (kcm->rx_wait) { 1121 list_del(&kcm->wait_rx_list); 1122 /* paired with lockless reads in kcm_rfree() */ 1123 WRITE_ONCE(kcm->rx_wait, false); 1124 } 1125 1126 requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue); 1127 } 1128 1129 spin_unlock_bh(&mux->rx_lock); 1130 } 1131 1132 /* kcm sock lock held */ 1133 static void kcm_recv_enable(struct kcm_sock *kcm) 1134 { 1135 struct kcm_mux *mux = kcm->mux; 1136 1137 if (!kcm->rx_disabled) 1138 return; 1139 1140 spin_lock_bh(&mux->rx_lock); 1141 1142 kcm->rx_disabled = 0; 1143 kcm_rcv_ready(kcm); 1144 1145 spin_unlock_bh(&mux->rx_lock); 1146 } 1147 1148 static int kcm_setsockopt(struct socket *sock, int level, int optname, 1149 sockptr_t optval, unsigned int optlen) 1150 { 1151 struct kcm_sock *kcm = kcm_sk(sock->sk); 1152 int val, valbool; 1153 int err = 0; 1154 1155 if (level != SOL_KCM) 1156 return -ENOPROTOOPT; 1157 1158 if (optlen < sizeof(int)) 1159 return -EINVAL; 1160 1161 if (copy_from_sockptr(&val, optval, sizeof(int))) 1162 return -EFAULT; 1163 1164 valbool = val ? 1 : 0; 1165 1166 switch (optname) { 1167 case KCM_RECV_DISABLE: 1168 lock_sock(&kcm->sk); 1169 if (valbool) 1170 kcm_recv_disable(kcm); 1171 else 1172 kcm_recv_enable(kcm); 1173 release_sock(&kcm->sk); 1174 break; 1175 default: 1176 err = -ENOPROTOOPT; 1177 } 1178 1179 return err; 1180 } 1181 1182 static int kcm_getsockopt(struct socket *sock, int level, int optname, 1183 char __user *optval, int __user *optlen) 1184 { 1185 struct kcm_sock *kcm = kcm_sk(sock->sk); 1186 int val, len; 1187 1188 if (level != SOL_KCM) 1189 return -ENOPROTOOPT; 1190 1191 if (get_user(len, optlen)) 1192 return -EFAULT; 1193 1194 len = min_t(unsigned int, len, sizeof(int)); 1195 if (len < 0) 1196 return -EINVAL; 1197 1198 switch (optname) { 1199 case KCM_RECV_DISABLE: 1200 val = kcm->rx_disabled; 1201 break; 1202 default: 1203 return -ENOPROTOOPT; 1204 } 1205 1206 if (put_user(len, optlen)) 1207 return -EFAULT; 1208 if (copy_to_user(optval, &val, len)) 1209 return -EFAULT; 1210 return 0; 1211 } 1212 1213 static void init_kcm_sock(struct kcm_sock *kcm, struct kcm_mux *mux) 1214 { 1215 struct kcm_sock *tkcm; 1216 struct list_head *head; 1217 int index = 0; 1218 1219 /* For SOCK_SEQPACKET sock type, datagram_poll checks the sk_state, so 1220 * we set sk_state, otherwise epoll_wait always returns right away with 1221 * EPOLLHUP 1222 */ 1223 kcm->sk.sk_state = TCP_ESTABLISHED; 1224 1225 /* Add to mux's kcm sockets list */ 1226 kcm->mux = mux; 1227 spin_lock_bh(&mux->lock); 1228 1229 head = &mux->kcm_socks; 1230 list_for_each_entry(tkcm, &mux->kcm_socks, kcm_sock_list) { 1231 if (tkcm->index != index) 1232 break; 1233 head = &tkcm->kcm_sock_list; 1234 index++; 1235 } 1236 1237 list_add(&kcm->kcm_sock_list, head); 1238 kcm->index = index; 1239 1240 mux->kcm_socks_cnt++; 1241 spin_unlock_bh(&mux->lock); 1242 1243 INIT_WORK(&kcm->tx_work, kcm_tx_work); 1244 1245 spin_lock_bh(&mux->rx_lock); 1246 kcm_rcv_ready(kcm); 1247 spin_unlock_bh(&mux->rx_lock); 1248 } 1249 1250 static int kcm_attach(struct socket *sock, struct socket *csock, 1251 struct bpf_prog *prog) 1252 { 1253 struct kcm_sock *kcm = kcm_sk(sock->sk); 1254 struct kcm_mux *mux = kcm->mux; 1255 struct sock *csk; 1256 struct kcm_psock *psock = NULL, *tpsock; 1257 struct list_head *head; 1258 int index = 0; 1259 static const struct strp_callbacks cb = { 1260 .rcv_msg = kcm_rcv_strparser, 1261 .parse_msg = kcm_parse_func_strparser, 1262 .read_sock_done = kcm_read_sock_done, 1263 }; 1264 int err = 0; 1265 1266 csk = csock->sk; 1267 if (!csk) 1268 return -EINVAL; 1269 1270 lock_sock(csk); 1271 1272 /* Only allow TCP sockets to be attached for now */ 1273 if ((csk->sk_family != AF_INET && csk->sk_family != AF_INET6) || 1274 csk->sk_protocol != IPPROTO_TCP) { 1275 err = -EOPNOTSUPP; 1276 goto out; 1277 } 1278 1279 /* Don't allow listeners or closed sockets */ 1280 if (csk->sk_state == TCP_LISTEN || csk->sk_state == TCP_CLOSE) { 1281 err = -EOPNOTSUPP; 1282 goto out; 1283 } 1284 1285 psock = kmem_cache_zalloc(kcm_psockp, GFP_KERNEL); 1286 if (!psock) { 1287 err = -ENOMEM; 1288 goto out; 1289 } 1290 1291 psock->mux = mux; 1292 psock->sk = csk; 1293 psock->bpf_prog = prog; 1294 1295 write_lock_bh(&csk->sk_callback_lock); 1296 1297 /* Check if sk_user_data is already by KCM or someone else. 1298 * Must be done under lock to prevent race conditions. 1299 */ 1300 if (csk->sk_user_data) { 1301 write_unlock_bh(&csk->sk_callback_lock); 1302 kmem_cache_free(kcm_psockp, psock); 1303 err = -EALREADY; 1304 goto out; 1305 } 1306 1307 err = strp_init(&psock->strp, csk, &cb); 1308 if (err) { 1309 write_unlock_bh(&csk->sk_callback_lock); 1310 kmem_cache_free(kcm_psockp, psock); 1311 goto out; 1312 } 1313 1314 psock->save_data_ready = csk->sk_data_ready; 1315 psock->save_write_space = csk->sk_write_space; 1316 psock->save_state_change = csk->sk_state_change; 1317 csk->sk_user_data = psock; 1318 csk->sk_data_ready = psock_data_ready; 1319 csk->sk_write_space = psock_write_space; 1320 csk->sk_state_change = psock_state_change; 1321 1322 write_unlock_bh(&csk->sk_callback_lock); 1323 1324 sock_hold(csk); 1325 1326 /* Finished initialization, now add the psock to the MUX. */ 1327 spin_lock_bh(&mux->lock); 1328 head = &mux->psocks; 1329 list_for_each_entry(tpsock, &mux->psocks, psock_list) { 1330 if (tpsock->index != index) 1331 break; 1332 head = &tpsock->psock_list; 1333 index++; 1334 } 1335 1336 list_add(&psock->psock_list, head); 1337 psock->index = index; 1338 1339 KCM_STATS_INCR(mux->stats.psock_attach); 1340 mux->psocks_cnt++; 1341 psock_now_avail(psock); 1342 spin_unlock_bh(&mux->lock); 1343 1344 /* Schedule RX work in case there are already bytes queued */ 1345 strp_check_rcv(&psock->strp); 1346 1347 out: 1348 release_sock(csk); 1349 1350 return err; 1351 } 1352 1353 static int kcm_attach_ioctl(struct socket *sock, struct kcm_attach *info) 1354 { 1355 struct socket *csock; 1356 struct bpf_prog *prog; 1357 int err; 1358 1359 csock = sockfd_lookup(info->fd, &err); 1360 if (!csock) 1361 return -ENOENT; 1362 1363 prog = bpf_prog_get_type(info->bpf_fd, BPF_PROG_TYPE_SOCKET_FILTER); 1364 if (IS_ERR(prog)) { 1365 err = PTR_ERR(prog); 1366 goto out; 1367 } 1368 1369 err = kcm_attach(sock, csock, prog); 1370 if (err) { 1371 bpf_prog_put(prog); 1372 goto out; 1373 } 1374 1375 /* Keep reference on file also */ 1376 1377 return 0; 1378 out: 1379 sockfd_put(csock); 1380 return err; 1381 } 1382 1383 static void kcm_unattach(struct kcm_psock *psock) 1384 { 1385 struct sock *csk = psock->sk; 1386 struct kcm_mux *mux = psock->mux; 1387 1388 lock_sock(csk); 1389 1390 /* Stop getting callbacks from TCP socket. After this there should 1391 * be no way to reserve a kcm for this psock. 1392 */ 1393 write_lock_bh(&csk->sk_callback_lock); 1394 csk->sk_user_data = NULL; 1395 csk->sk_data_ready = psock->save_data_ready; 1396 csk->sk_write_space = psock->save_write_space; 1397 csk->sk_state_change = psock->save_state_change; 1398 strp_stop(&psock->strp); 1399 1400 if (WARN_ON(psock->rx_kcm)) { 1401 write_unlock_bh(&csk->sk_callback_lock); 1402 release_sock(csk); 1403 return; 1404 } 1405 1406 spin_lock_bh(&mux->rx_lock); 1407 1408 /* Stop receiver activities. After this point psock should not be 1409 * able to get onto ready list either through callbacks or work. 1410 */ 1411 if (psock->ready_rx_msg) { 1412 list_del(&psock->psock_ready_list); 1413 kfree_skb(psock->ready_rx_msg); 1414 psock->ready_rx_msg = NULL; 1415 KCM_STATS_INCR(mux->stats.rx_ready_drops); 1416 } 1417 1418 spin_unlock_bh(&mux->rx_lock); 1419 1420 write_unlock_bh(&csk->sk_callback_lock); 1421 1422 /* Call strp_done without sock lock */ 1423 release_sock(csk); 1424 strp_done(&psock->strp); 1425 lock_sock(csk); 1426 1427 bpf_prog_put(psock->bpf_prog); 1428 1429 spin_lock_bh(&mux->lock); 1430 1431 aggregate_psock_stats(&psock->stats, &mux->aggregate_psock_stats); 1432 save_strp_stats(&psock->strp, &mux->aggregate_strp_stats); 1433 1434 KCM_STATS_INCR(mux->stats.psock_unattach); 1435 1436 if (psock->tx_kcm) { 1437 /* psock was reserved. Just mark it finished and we will clean 1438 * up in the kcm paths, we need kcm lock which can not be 1439 * acquired here. 1440 */ 1441 KCM_STATS_INCR(mux->stats.psock_unattach_rsvd); 1442 spin_unlock_bh(&mux->lock); 1443 1444 /* We are unattaching a socket that is reserved. Abort the 1445 * socket since we may be out of sync in sending on it. We need 1446 * to do this without the mux lock. 1447 */ 1448 kcm_abort_tx_psock(psock, EPIPE, false); 1449 1450 spin_lock_bh(&mux->lock); 1451 if (!psock->tx_kcm) { 1452 /* psock now unreserved in window mux was unlocked */ 1453 goto no_reserved; 1454 } 1455 psock->done = 1; 1456 1457 /* Commit done before queuing work to process it */ 1458 smp_mb(); 1459 1460 /* Queue tx work to make sure psock->done is handled */ 1461 queue_work(kcm_wq, &psock->tx_kcm->tx_work); 1462 spin_unlock_bh(&mux->lock); 1463 } else { 1464 no_reserved: 1465 if (!psock->tx_stopped) 1466 list_del(&psock->psock_avail_list); 1467 list_del(&psock->psock_list); 1468 mux->psocks_cnt--; 1469 spin_unlock_bh(&mux->lock); 1470 1471 sock_put(csk); 1472 fput(csk->sk_socket->file); 1473 kmem_cache_free(kcm_psockp, psock); 1474 } 1475 1476 release_sock(csk); 1477 } 1478 1479 static int kcm_unattach_ioctl(struct socket *sock, struct kcm_unattach *info) 1480 { 1481 struct kcm_sock *kcm = kcm_sk(sock->sk); 1482 struct kcm_mux *mux = kcm->mux; 1483 struct kcm_psock *psock; 1484 struct socket *csock; 1485 struct sock *csk; 1486 int err; 1487 1488 csock = sockfd_lookup(info->fd, &err); 1489 if (!csock) 1490 return -ENOENT; 1491 1492 csk = csock->sk; 1493 if (!csk) { 1494 err = -EINVAL; 1495 goto out; 1496 } 1497 1498 err = -ENOENT; 1499 1500 spin_lock_bh(&mux->lock); 1501 1502 list_for_each_entry(psock, &mux->psocks, psock_list) { 1503 if (psock->sk != csk) 1504 continue; 1505 1506 /* Found the matching psock */ 1507 1508 if (psock->unattaching || WARN_ON(psock->done)) { 1509 err = -EALREADY; 1510 break; 1511 } 1512 1513 psock->unattaching = 1; 1514 1515 spin_unlock_bh(&mux->lock); 1516 1517 /* Lower socket lock should already be held */ 1518 kcm_unattach(psock); 1519 1520 err = 0; 1521 goto out; 1522 } 1523 1524 spin_unlock_bh(&mux->lock); 1525 1526 out: 1527 sockfd_put(csock); 1528 return err; 1529 } 1530 1531 static struct proto kcm_proto = { 1532 .name = "KCM", 1533 .owner = THIS_MODULE, 1534 .obj_size = sizeof(struct kcm_sock), 1535 }; 1536 1537 /* Clone a kcm socket. */ 1538 static struct file *kcm_clone(struct socket *osock) 1539 { 1540 struct socket *newsock; 1541 struct sock *newsk; 1542 1543 newsock = sock_alloc(); 1544 if (!newsock) 1545 return ERR_PTR(-ENFILE); 1546 1547 newsock->type = osock->type; 1548 newsock->ops = osock->ops; 1549 1550 __module_get(newsock->ops->owner); 1551 1552 newsk = sk_alloc(sock_net(osock->sk), PF_KCM, GFP_KERNEL, 1553 &kcm_proto, false); 1554 if (!newsk) { 1555 sock_release(newsock); 1556 return ERR_PTR(-ENOMEM); 1557 } 1558 sock_init_data(newsock, newsk); 1559 init_kcm_sock(kcm_sk(newsk), kcm_sk(osock->sk)->mux); 1560 1561 return sock_alloc_file(newsock, 0, osock->sk->sk_prot_creator->name); 1562 } 1563 1564 static int kcm_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg) 1565 { 1566 int err; 1567 1568 switch (cmd) { 1569 case SIOCKCMATTACH: { 1570 struct kcm_attach info; 1571 1572 if (copy_from_user(&info, (void __user *)arg, sizeof(info))) 1573 return -EFAULT; 1574 1575 err = kcm_attach_ioctl(sock, &info); 1576 1577 break; 1578 } 1579 case SIOCKCMUNATTACH: { 1580 struct kcm_unattach info; 1581 1582 if (copy_from_user(&info, (void __user *)arg, sizeof(info))) 1583 return -EFAULT; 1584 1585 err = kcm_unattach_ioctl(sock, &info); 1586 1587 break; 1588 } 1589 case SIOCKCMCLONE: { 1590 struct kcm_clone info; 1591 struct file *file; 1592 1593 info.fd = get_unused_fd_flags(0); 1594 if (unlikely(info.fd < 0)) 1595 return info.fd; 1596 1597 file = kcm_clone(sock); 1598 if (IS_ERR(file)) { 1599 put_unused_fd(info.fd); 1600 return PTR_ERR(file); 1601 } 1602 if (copy_to_user((void __user *)arg, &info, 1603 sizeof(info))) { 1604 put_unused_fd(info.fd); 1605 fput(file); 1606 return -EFAULT; 1607 } 1608 fd_install(info.fd, file); 1609 err = 0; 1610 break; 1611 } 1612 default: 1613 err = -ENOIOCTLCMD; 1614 break; 1615 } 1616 1617 return err; 1618 } 1619 1620 static void free_mux(struct rcu_head *rcu) 1621 { 1622 struct kcm_mux *mux = container_of(rcu, 1623 struct kcm_mux, rcu); 1624 1625 kmem_cache_free(kcm_muxp, mux); 1626 } 1627 1628 static void release_mux(struct kcm_mux *mux) 1629 { 1630 struct kcm_net *knet = mux->knet; 1631 struct kcm_psock *psock, *tmp_psock; 1632 1633 /* Release psocks */ 1634 list_for_each_entry_safe(psock, tmp_psock, 1635 &mux->psocks, psock_list) { 1636 if (!WARN_ON(psock->unattaching)) 1637 kcm_unattach(psock); 1638 } 1639 1640 if (WARN_ON(mux->psocks_cnt)) 1641 return; 1642 1643 __skb_queue_purge(&mux->rx_hold_queue); 1644 1645 mutex_lock(&knet->mutex); 1646 aggregate_mux_stats(&mux->stats, &knet->aggregate_mux_stats); 1647 aggregate_psock_stats(&mux->aggregate_psock_stats, 1648 &knet->aggregate_psock_stats); 1649 aggregate_strp_stats(&mux->aggregate_strp_stats, 1650 &knet->aggregate_strp_stats); 1651 list_del_rcu(&mux->kcm_mux_list); 1652 knet->count--; 1653 mutex_unlock(&knet->mutex); 1654 1655 call_rcu(&mux->rcu, free_mux); 1656 } 1657 1658 static void kcm_done(struct kcm_sock *kcm) 1659 { 1660 struct kcm_mux *mux = kcm->mux; 1661 struct sock *sk = &kcm->sk; 1662 int socks_cnt; 1663 1664 spin_lock_bh(&mux->rx_lock); 1665 if (kcm->rx_psock) { 1666 /* Cleanup in unreserve_rx_kcm */ 1667 WARN_ON(kcm->done); 1668 kcm->rx_disabled = 1; 1669 kcm->done = 1; 1670 spin_unlock_bh(&mux->rx_lock); 1671 return; 1672 } 1673 1674 if (kcm->rx_wait) { 1675 list_del(&kcm->wait_rx_list); 1676 /* paired with lockless reads in kcm_rfree() */ 1677 WRITE_ONCE(kcm->rx_wait, false); 1678 } 1679 /* Move any pending receive messages to other kcm sockets */ 1680 requeue_rx_msgs(mux, &sk->sk_receive_queue); 1681 1682 spin_unlock_bh(&mux->rx_lock); 1683 1684 if (WARN_ON(sk_rmem_alloc_get(sk))) 1685 return; 1686 1687 /* Detach from MUX */ 1688 spin_lock_bh(&mux->lock); 1689 1690 list_del(&kcm->kcm_sock_list); 1691 mux->kcm_socks_cnt--; 1692 socks_cnt = mux->kcm_socks_cnt; 1693 1694 spin_unlock_bh(&mux->lock); 1695 1696 if (!socks_cnt) { 1697 /* We are done with the mux now. */ 1698 release_mux(mux); 1699 } 1700 1701 WARN_ON(kcm->rx_wait); 1702 1703 sock_put(&kcm->sk); 1704 } 1705 1706 /* Called by kcm_release to close a KCM socket. 1707 * If this is the last KCM socket on the MUX, destroy the MUX. 1708 */ 1709 static int kcm_release(struct socket *sock) 1710 { 1711 struct sock *sk = sock->sk; 1712 struct kcm_sock *kcm; 1713 struct kcm_mux *mux; 1714 struct kcm_psock *psock; 1715 1716 if (!sk) 1717 return 0; 1718 1719 kcm = kcm_sk(sk); 1720 mux = kcm->mux; 1721 1722 lock_sock(sk); 1723 sock_orphan(sk); 1724 kfree_skb(kcm->seq_skb); 1725 1726 /* Purge queue under lock to avoid race condition with tx_work trying 1727 * to act when queue is nonempty. If tx_work runs after this point 1728 * it will just return. 1729 */ 1730 __skb_queue_purge(&sk->sk_write_queue); 1731 1732 /* Set tx_stopped. This is checked when psock is bound to a kcm and we 1733 * get a writespace callback. This prevents further work being queued 1734 * from the callback (unbinding the psock occurs after canceling work. 1735 */ 1736 kcm->tx_stopped = 1; 1737 1738 release_sock(sk); 1739 1740 spin_lock_bh(&mux->lock); 1741 if (kcm->tx_wait) { 1742 /* Take of tx_wait list, after this point there should be no way 1743 * that a psock will be assigned to this kcm. 1744 */ 1745 list_del(&kcm->wait_psock_list); 1746 kcm->tx_wait = false; 1747 } 1748 spin_unlock_bh(&mux->lock); 1749 1750 /* Cancel work. After this point there should be no outside references 1751 * to the kcm socket. 1752 */ 1753 cancel_work_sync(&kcm->tx_work); 1754 1755 lock_sock(sk); 1756 psock = kcm->tx_psock; 1757 if (psock) { 1758 /* A psock was reserved, so we need to kill it since it 1759 * may already have some bytes queued from a message. We 1760 * need to do this after removing kcm from tx_wait list. 1761 */ 1762 kcm_abort_tx_psock(psock, EPIPE, false); 1763 unreserve_psock(kcm); 1764 } 1765 release_sock(sk); 1766 1767 WARN_ON(kcm->tx_wait); 1768 WARN_ON(kcm->tx_psock); 1769 1770 sock->sk = NULL; 1771 1772 kcm_done(kcm); 1773 1774 return 0; 1775 } 1776 1777 static const struct proto_ops kcm_dgram_ops = { 1778 .family = PF_KCM, 1779 .owner = THIS_MODULE, 1780 .release = kcm_release, 1781 .bind = sock_no_bind, 1782 .connect = sock_no_connect, 1783 .socketpair = sock_no_socketpair, 1784 .accept = sock_no_accept, 1785 .getname = sock_no_getname, 1786 .poll = datagram_poll, 1787 .ioctl = kcm_ioctl, 1788 .listen = sock_no_listen, 1789 .shutdown = sock_no_shutdown, 1790 .setsockopt = kcm_setsockopt, 1791 .getsockopt = kcm_getsockopt, 1792 .sendmsg = kcm_sendmsg, 1793 .recvmsg = kcm_recvmsg, 1794 .mmap = sock_no_mmap, 1795 .splice_eof = kcm_splice_eof, 1796 .sendpage = kcm_sendpage, 1797 }; 1798 1799 static const struct proto_ops kcm_seqpacket_ops = { 1800 .family = PF_KCM, 1801 .owner = THIS_MODULE, 1802 .release = kcm_release, 1803 .bind = sock_no_bind, 1804 .connect = sock_no_connect, 1805 .socketpair = sock_no_socketpair, 1806 .accept = sock_no_accept, 1807 .getname = sock_no_getname, 1808 .poll = datagram_poll, 1809 .ioctl = kcm_ioctl, 1810 .listen = sock_no_listen, 1811 .shutdown = sock_no_shutdown, 1812 .setsockopt = kcm_setsockopt, 1813 .getsockopt = kcm_getsockopt, 1814 .sendmsg = kcm_sendmsg, 1815 .recvmsg = kcm_recvmsg, 1816 .mmap = sock_no_mmap, 1817 .splice_eof = kcm_splice_eof, 1818 .sendpage = kcm_sendpage, 1819 .splice_read = kcm_splice_read, 1820 }; 1821 1822 /* Create proto operation for kcm sockets */ 1823 static int kcm_create(struct net *net, struct socket *sock, 1824 int protocol, int kern) 1825 { 1826 struct kcm_net *knet = net_generic(net, kcm_net_id); 1827 struct sock *sk; 1828 struct kcm_mux *mux; 1829 1830 switch (sock->type) { 1831 case SOCK_DGRAM: 1832 sock->ops = &kcm_dgram_ops; 1833 break; 1834 case SOCK_SEQPACKET: 1835 sock->ops = &kcm_seqpacket_ops; 1836 break; 1837 default: 1838 return -ESOCKTNOSUPPORT; 1839 } 1840 1841 if (protocol != KCMPROTO_CONNECTED) 1842 return -EPROTONOSUPPORT; 1843 1844 sk = sk_alloc(net, PF_KCM, GFP_KERNEL, &kcm_proto, kern); 1845 if (!sk) 1846 return -ENOMEM; 1847 1848 /* Allocate a kcm mux, shared between KCM sockets */ 1849 mux = kmem_cache_zalloc(kcm_muxp, GFP_KERNEL); 1850 if (!mux) { 1851 sk_free(sk); 1852 return -ENOMEM; 1853 } 1854 1855 spin_lock_init(&mux->lock); 1856 spin_lock_init(&mux->rx_lock); 1857 INIT_LIST_HEAD(&mux->kcm_socks); 1858 INIT_LIST_HEAD(&mux->kcm_rx_waiters); 1859 INIT_LIST_HEAD(&mux->kcm_tx_waiters); 1860 1861 INIT_LIST_HEAD(&mux->psocks); 1862 INIT_LIST_HEAD(&mux->psocks_ready); 1863 INIT_LIST_HEAD(&mux->psocks_avail); 1864 1865 mux->knet = knet; 1866 1867 /* Add new MUX to list */ 1868 mutex_lock(&knet->mutex); 1869 list_add_rcu(&mux->kcm_mux_list, &knet->mux_list); 1870 knet->count++; 1871 mutex_unlock(&knet->mutex); 1872 1873 skb_queue_head_init(&mux->rx_hold_queue); 1874 1875 /* Init KCM socket */ 1876 sock_init_data(sock, sk); 1877 init_kcm_sock(kcm_sk(sk), mux); 1878 1879 return 0; 1880 } 1881 1882 static const struct net_proto_family kcm_family_ops = { 1883 .family = PF_KCM, 1884 .create = kcm_create, 1885 .owner = THIS_MODULE, 1886 }; 1887 1888 static __net_init int kcm_init_net(struct net *net) 1889 { 1890 struct kcm_net *knet = net_generic(net, kcm_net_id); 1891 1892 INIT_LIST_HEAD_RCU(&knet->mux_list); 1893 mutex_init(&knet->mutex); 1894 1895 return 0; 1896 } 1897 1898 static __net_exit void kcm_exit_net(struct net *net) 1899 { 1900 struct kcm_net *knet = net_generic(net, kcm_net_id); 1901 1902 /* All KCM sockets should be closed at this point, which should mean 1903 * that all multiplexors and psocks have been destroyed. 1904 */ 1905 WARN_ON(!list_empty(&knet->mux_list)); 1906 } 1907 1908 static struct pernet_operations kcm_net_ops = { 1909 .init = kcm_init_net, 1910 .exit = kcm_exit_net, 1911 .id = &kcm_net_id, 1912 .size = sizeof(struct kcm_net), 1913 }; 1914 1915 static int __init kcm_init(void) 1916 { 1917 int err = -ENOMEM; 1918 1919 kcm_muxp = kmem_cache_create("kcm_mux_cache", 1920 sizeof(struct kcm_mux), 0, 1921 SLAB_HWCACHE_ALIGN, NULL); 1922 if (!kcm_muxp) 1923 goto fail; 1924 1925 kcm_psockp = kmem_cache_create("kcm_psock_cache", 1926 sizeof(struct kcm_psock), 0, 1927 SLAB_HWCACHE_ALIGN, NULL); 1928 if (!kcm_psockp) 1929 goto fail; 1930 1931 kcm_wq = create_singlethread_workqueue("kkcmd"); 1932 if (!kcm_wq) 1933 goto fail; 1934 1935 err = proto_register(&kcm_proto, 1); 1936 if (err) 1937 goto fail; 1938 1939 err = register_pernet_device(&kcm_net_ops); 1940 if (err) 1941 goto net_ops_fail; 1942 1943 err = sock_register(&kcm_family_ops); 1944 if (err) 1945 goto sock_register_fail; 1946 1947 err = kcm_proc_init(); 1948 if (err) 1949 goto proc_init_fail; 1950 1951 return 0; 1952 1953 proc_init_fail: 1954 sock_unregister(PF_KCM); 1955 1956 sock_register_fail: 1957 unregister_pernet_device(&kcm_net_ops); 1958 1959 net_ops_fail: 1960 proto_unregister(&kcm_proto); 1961 1962 fail: 1963 kmem_cache_destroy(kcm_muxp); 1964 kmem_cache_destroy(kcm_psockp); 1965 1966 if (kcm_wq) 1967 destroy_workqueue(kcm_wq); 1968 1969 return err; 1970 } 1971 1972 static void __exit kcm_exit(void) 1973 { 1974 kcm_proc_exit(); 1975 sock_unregister(PF_KCM); 1976 unregister_pernet_device(&kcm_net_ops); 1977 proto_unregister(&kcm_proto); 1978 destroy_workqueue(kcm_wq); 1979 1980 kmem_cache_destroy(kcm_muxp); 1981 kmem_cache_destroy(kcm_psockp); 1982 } 1983 1984 module_init(kcm_init); 1985 module_exit(kcm_exit); 1986 1987 MODULE_LICENSE("GPL"); 1988 MODULE_ALIAS_NETPROTO(PF_KCM); 1989