net/rxrpc/call_accept.c

   1 /* incoming call handling
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/module.h>
  15 #include <linux/net.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/errqueue.h>
  18 #include <linux/udp.h>
  19 #include <linux/in.h>
  20 #include <linux/in6.h>
  21 #include <linux/icmp.h>
  22 #include <linux/gfp.h>
  23 #include <linux/circ_buf.h>
  24 #include <net/sock.h>
  25 #include <net/af_rxrpc.h>
  26 #include <net/ip.h>
  27 #include "ar-internal.h"
  28
  29 /*
  30  * Preallocate a single service call, connection and peer and, if possible,
  31  * give them a user ID and attach the user's side of the ID to them.
  32  */
  33 static int rxrpc_service_prealloc_one(struct rxrpc_sock *rx,
  34                                       struct rxrpc_backlog *b,
  35                                       rxrpc_notify_rx_t notify_rx,
  36                                       rxrpc_user_attach_call_t user_attach_call,
  37                                       unsigned long user_call_ID, gfp_t gfp)
  38 {
  39         const void *here = __builtin_return_address(0);
  40         struct rxrpc_call *call;
  41         int max, tmp;
  42         unsigned int size = RXRPC_BACKLOG_MAX;
  43         unsigned int head, tail, call_head, call_tail;
  44
  45         max = rx->sk.sk_max_ack_backlog;
  46         tmp = rx->sk.sk_ack_backlog;
  47         if (tmp >= max) {
  48                 _leave(" = -ENOBUFS [full %u]", max);
  49                 return -ENOBUFS;
  50         }
  51         max -= tmp;
  52
  53         /* We don't need more conns and peers than we have calls, but on the
  54          * other hand, we shouldn't ever use more peers than conns or conns
  55          * than calls.
  56          */
  57         call_head = b->call_backlog_head;
  58         call_tail = READ_ONCE(b->call_backlog_tail);
  59         tmp = CIRC_CNT(call_head, call_tail, size);
  60         if (tmp >= max) {
  61                 _leave(" = -ENOBUFS [enough %u]", tmp);
  62                 return -ENOBUFS;
  63         }
  64         max = tmp + 1;
  65
  66         head = b->peer_backlog_head;
  67         tail = READ_ONCE(b->peer_backlog_tail);
  68         if (CIRC_CNT(head, tail, size) < max) {
  69                 struct rxrpc_peer *peer = rxrpc_alloc_peer(rx->local, gfp);
  70                 if (!peer)
  71                         return -ENOMEM;
  72                 b->peer_backlog[head] = peer;
  73                 smp_store_release(&b->peer_backlog_head,
  74                                   (head + 1) & (size - 1));
  75         }
  76
  77         head = b->conn_backlog_head;
  78         tail = READ_ONCE(b->conn_backlog_tail);
  79         if (CIRC_CNT(head, tail, size) < max) {
  80                 struct rxrpc_connection *conn;
  81
  82                 conn = rxrpc_prealloc_service_connection(gfp);
  83                 if (!conn)
  84                         return -ENOMEM;
  85                 b->conn_backlog[head] = conn;
  86                 smp_store_release(&b->conn_backlog_head,
  87                                   (head + 1) & (size - 1));
  88         }
  89
  90         /* Now it gets complicated, because calls get registered with the
  91          * socket here, particularly if a user ID is preassigned by the user.
  92          */
  93         call = rxrpc_alloc_call(gfp);
  94         if (!call)
  95                 return -ENOMEM;
  96         call->flags |= (1 << RXRPC_CALL_IS_SERVICE);
  97         call->state = RXRPC_CALL_SERVER_PREALLOC;
  98
  99         trace_rxrpc_call(call, rxrpc_call_new_service,
 100                          atomic_read(&call->usage),
 101                          here, (const void *)user_call_ID);
 102
 103         write_lock(&rx->call_lock);
 104         if (user_attach_call) {
 105                 struct rxrpc_call *xcall;
 106                 struct rb_node *parent, **pp;
 107
 108                 /* Check the user ID isn't already in use */
 109                 pp = &rx->calls.rb_node;
 110                 parent = NULL;
 111                 while (*pp) {
 112                         parent = *pp;
 113                         xcall = rb_entry(parent, struct rxrpc_call, sock_node);
 114                         if (user_call_ID < call->user_call_ID)
 115                                 pp = &(*pp)->rb_left;
 116                         else if (user_call_ID > call->user_call_ID)
 117                                 pp = &(*pp)->rb_right;
 118                         else
 119                                 goto id_in_use;
 120                 }
 121
 122                 call->user_call_ID = user_call_ID;
 123                 call->notify_rx = notify_rx;
 124                 rxrpc_get_call(call, rxrpc_call_got);
 125                 user_attach_call(call, user_call_ID);
 126                 rxrpc_get_call(call, rxrpc_call_got_userid);
 127                 rb_link_node(&call->sock_node, parent, pp);
 128                 rb_insert_color(&call->sock_node, &rx->calls);
 129                 set_bit(RXRPC_CALL_HAS_USERID, &call->flags);
 130         }
 131
 132         list_add(&call->sock_link, &rx->sock_calls);
 133
 134         write_unlock(&rx->call_lock);
 135
 136         write_lock(&rxrpc_call_lock);
 137         list_add_tail(&call->link, &rxrpc_calls);
 138         write_unlock(&rxrpc_call_lock);
 139
 140         b->call_backlog[call_head] = call;
 141         smp_store_release(&b->call_backlog_head, (call_head + 1) & (size - 1));
 142         _leave(" = 0 [%d -> %lx]", call->debug_id, user_call_ID);
 143         return 0;
 144
 145 id_in_use:
 146         write_unlock(&rx->call_lock);
 147         rxrpc_cleanup_call(call);
 148         _leave(" = -EBADSLT");
 149         return -EBADSLT;
 150 }
 151
 152 /*
 153  * Preallocate sufficient service connections, calls and peers to cover the
 154  * entire backlog of a socket.  When a new call comes in, if we don't have
 155  * sufficient of each available, the call gets rejected as busy or ignored.
 156  *
 157  * The backlog is replenished when a connection is accepted or rejected.
 158  */
 159 int rxrpc_service_prealloc(struct rxrpc_sock *rx, gfp_t gfp)
 160 {
 161         struct rxrpc_backlog *b = rx->backlog;
 162
 163         if (!b) {
 164                 b = kzalloc(sizeof(struct rxrpc_backlog), gfp);
 165                 if (!b)
 166                         return -ENOMEM;
 167                 rx->backlog = b;
 168         }
 169
 170         if (rx->discard_new_call)
 171                 return 0;
 172
 173         while (rxrpc_service_prealloc_one(rx, b, NULL, NULL, 0, gfp) == 0)
 174                 ;
 175
 176         return 0;
 177 }
 178
 179 /*
 180  * Discard the preallocation on a service.
 181  */
 182 void rxrpc_discard_prealloc(struct rxrpc_sock *rx)
 183 {
 184         struct rxrpc_backlog *b = rx->backlog;
 185         unsigned int size = RXRPC_BACKLOG_MAX, head, tail;
 186
 187         if (!b)
 188                 return;
 189         rx->backlog = NULL;
 190
 191         /* Make sure that there aren't any incoming calls in progress before we
 192          * clear the preallocation buffers.
 193          */
 194         spin_lock_bh(&rx->incoming_lock);
 195         spin_unlock_bh(&rx->incoming_lock);
 196
 197         head = b->peer_backlog_head;
 198         tail = b->peer_backlog_tail;
 199         while (CIRC_CNT(head, tail, size) > 0) {
 200                 struct rxrpc_peer *peer = b->peer_backlog[tail];
 201                 kfree(peer);
 202                 tail = (tail + 1) & (size - 1);
 203         }
 204
 205         head = b->conn_backlog_head;
 206         tail = b->conn_backlog_tail;
 207         while (CIRC_CNT(head, tail, size) > 0) {
 208                 struct rxrpc_connection *conn = b->conn_backlog[tail];
 209                 write_lock(&rxrpc_connection_lock);
 210                 list_del(&conn->link);
 211                 list_del(&conn->proc_link);
 212                 write_unlock(&rxrpc_connection_lock);
 213                 kfree(conn);
 214                 tail = (tail + 1) & (size - 1);
 215         }
 216
 217         head = b->call_backlog_head;
 218         tail = b->call_backlog_tail;
 219         while (CIRC_CNT(head, tail, size) > 0) {
 220                 struct rxrpc_call *call = b->call_backlog[tail];
 221                 if (rx->discard_new_call) {
 222                         _debug("discard %lx", call->user_call_ID);
 223                         rx->discard_new_call(call, call->user_call_ID);
 224                 }
 225                 rxrpc_call_completed(call);
 226                 rxrpc_release_call(rx, call);
 227                 rxrpc_put_call(call, rxrpc_call_put);
 228                 tail = (tail + 1) & (size - 1);
 229         }
 230
 231         kfree(b);
 232 }
 233
 234 /*
 235  * Allocate a new incoming call from the prealloc pool, along with a connection
 236  * and a peer as necessary.
 237  */
 238 static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx,
 239                                                     struct rxrpc_local *local,
 240                                                     struct rxrpc_connection *conn,
 241                                                     struct sk_buff *skb)
 242 {
 243         struct rxrpc_backlog *b = rx->backlog;
 244         struct rxrpc_peer *peer, *xpeer;
 245         struct rxrpc_call *call;
 246         unsigned short call_head, conn_head, peer_head;
 247         unsigned short call_tail, conn_tail, peer_tail;
 248         unsigned short call_count, conn_count;
 249
 250         /* #calls >= #conns >= #peers must hold true. */
 251         call_head = smp_load_acquire(&b->call_backlog_head);
 252         call_tail = b->call_backlog_tail;
 253         call_count = CIRC_CNT(call_head, call_tail, RXRPC_BACKLOG_MAX);
 254         conn_head = smp_load_acquire(&b->conn_backlog_head);
 255         conn_tail = b->conn_backlog_tail;
 256         conn_count = CIRC_CNT(conn_head, conn_tail, RXRPC_BACKLOG_MAX);
 257         ASSERTCMP(conn_count, >=, call_count);
 258         peer_head = smp_load_acquire(&b->peer_backlog_head);
 259         peer_tail = b->peer_backlog_tail;
 260         ASSERTCMP(CIRC_CNT(peer_head, peer_tail, RXRPC_BACKLOG_MAX), >=,
 261                   conn_count);
 262
 263         if (call_count == 0)
 264                 return NULL;
 265
 266         if (!conn) {
 267                 /* No connection.  We're going to need a peer to start off
 268                  * with.  If one doesn't yet exist, use a spare from the
 269                  * preallocation set.  We dump the address into the spare in
 270                  * anticipation - and to save on stack space.
 271                  */
 272                 xpeer = b->peer_backlog[peer_tail];
 273                 if (rxrpc_extract_addr_from_skb(&xpeer->srx, skb) < 0)
 274                         return NULL;
 275
 276                 peer = rxrpc_lookup_incoming_peer(local, xpeer);
 277                 if (peer == xpeer) {
 278                         b->peer_backlog[peer_tail] = NULL;
 279                         smp_store_release(&b->peer_backlog_tail,
 280                                           (peer_tail + 1) &
 281                                           (RXRPC_BACKLOG_MAX - 1));
 282                 }
 283
 284                 /* Now allocate and set up the connection */
 285                 conn = b->conn_backlog[conn_tail];
 286                 b->conn_backlog[conn_tail] = NULL;
 287                 smp_store_release(&b->conn_backlog_tail,
 288                                   (conn_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
 289                 rxrpc_get_local(local);
 290                 conn->params.local = local;
 291                 conn->params.peer = peer;
 292                 rxrpc_new_incoming_connection(conn, skb);
 293         } else {
 294                 rxrpc_get_connection(conn);
 295         }
 296
 297         /* And now we can allocate and set up a new call */
 298         call = b->call_backlog[call_tail];
 299         b->call_backlog[call_tail] = NULL;
 300         smp_store_release(&b->call_backlog_tail,
 301                           (call_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
 302
 303         call->conn = conn;
 304         call->peer = rxrpc_get_peer(conn->params.peer);
 305         return call;
 306 }
 307
 308 /*
 309  * Set up a new incoming call.  Called in BH context with the RCU read lock
 310  * held.
 311  *
 312  * If this is for a kernel service, when we allocate the call, it will have
 313  * three refs on it: (1) the kernel service, (2) the user_call_ID tree, (3) the
 314  * retainer ref obtained from the backlog buffer.  Prealloc calls for userspace
 315  * services only have the ref from the backlog buffer.  We want to pass this
 316  * ref to non-BH context to dispose of.
 317  *
 318  * If we want to report an error, we mark the skb with the packet type and
 319  * abort code and return NULL.
 320  */
 321 struct rxrpc_call *rxrpc_new_incoming_call(struct rxrpc_local *local,
 322                                            struct rxrpc_connection *conn,
 323                                            struct sk_buff *skb)
 324 {
 325         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 326         struct rxrpc_sock *rx;
 327         struct rxrpc_call *call;
 328
 329         _enter("");
 330
 331         /* Get the socket providing the service */
 332         hlist_for_each_entry_rcu_bh(rx, &local->services, listen_link) {
 333                 if (rx->srx.srx_service == sp->hdr.serviceId)
 334                         goto found_service;
 335         }
 336
 337         trace_rxrpc_abort("INV", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
 338                           RX_INVALID_OPERATION, EOPNOTSUPP);
 339         skb->mark = RXRPC_SKB_MARK_LOCAL_ABORT;
 340         skb->priority = RX_INVALID_OPERATION;
 341         _leave(" = NULL [service]");
 342         return NULL;
 343
 344 found_service:
 345         spin_lock(&rx->incoming_lock);
 346         if (rx->sk.sk_state == RXRPC_CLOSE) {
 347                 trace_rxrpc_abort("CLS", sp->hdr.cid, sp->hdr.callNumber,
 348                                   sp->hdr.seq, RX_INVALID_OPERATION, ESHUTDOWN);
 349                 skb->mark = RXRPC_SKB_MARK_LOCAL_ABORT;
 350                 skb->priority = RX_INVALID_OPERATION;
 351                 _leave(" = NULL [close]");
 352                 call = NULL;
 353                 goto out;
 354         }
 355
 356         call = rxrpc_alloc_incoming_call(rx, local, conn, skb);
 357         if (!call) {
 358                 skb->mark = RXRPC_SKB_MARK_BUSY;
 359                 _leave(" = NULL [busy]");
 360                 call = NULL;
 361                 goto out;
 362         }
 363
 364         /* Make the call live. */
 365         rxrpc_incoming_call(rx, call, skb);
 366         conn = call->conn;
 367
 368         if (rx->notify_new_call)
 369                 rx->notify_new_call(&rx->sk, call, call->user_call_ID);
 370
 371         spin_lock(&conn->state_lock);
 372         switch (conn->state) {
 373         case RXRPC_CONN_SERVICE_UNSECURED:
 374                 conn->state = RXRPC_CONN_SERVICE_CHALLENGING;
 375                 set_bit(RXRPC_CONN_EV_CHALLENGE, &call->conn->events);
 376                 rxrpc_queue_conn(call->conn);
 377                 break;
 378
 379         case RXRPC_CONN_SERVICE:
 380                 write_lock(&call->state_lock);
 381                 if (rx->discard_new_call)
 382                         call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
 383                 else
 384                         call->state = RXRPC_CALL_SERVER_ACCEPTING;
 385                 write_unlock(&call->state_lock);
 386                 break;
 387
 388         case RXRPC_CONN_REMOTELY_ABORTED:
 389                 rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
 390                                           conn->remote_abort, ECONNABORTED);
 391                 break;
 392         case RXRPC_CONN_LOCALLY_ABORTED:
 393                 rxrpc_abort_call("CON", call, sp->hdr.seq,
 394                                  conn->local_abort, ECONNABORTED);
 395                 break;
 396         default:
 397                 BUG();
 398         }
 399         spin_unlock(&conn->state_lock);
 400
 401         if (call->state == RXRPC_CALL_SERVER_ACCEPTING)
 402                 rxrpc_notify_socket(call);
 403
 404         _leave(" = %p{%d}", call, call->debug_id);
 405 out:
 406         spin_unlock(&rx->incoming_lock);
 407         return call;
 408 }
 409
 410 /*
 411  * handle acceptance of a call by userspace
 412  * - assign the user call ID to the call at the front of the queue
 413  */
 414 struct rxrpc_call *rxrpc_accept_call(struct rxrpc_sock *rx,
 415                                      unsigned long user_call_ID,
 416                                      rxrpc_notify_rx_t notify_rx)
 417 {
 418         struct rxrpc_call *call;
 419         struct rb_node *parent, **pp;
 420         int ret;
 421
 422         _enter(",%lx", user_call_ID);
 423
 424         ASSERT(!irqs_disabled());
 425
 426         write_lock(&rx->call_lock);
 427
 428         ret = -ENODATA;
 429         if (list_empty(&rx->to_be_accepted))
 430                 goto out;
 431
 432         /* check the user ID isn't already in use */
 433         pp = &rx->calls.rb_node;
 434         parent = NULL;
 435         while (*pp) {
 436                 parent = *pp;
 437                 call = rb_entry(parent, struct rxrpc_call, sock_node);
 438
 439                 if (user_call_ID < call->user_call_ID)
 440                         pp = &(*pp)->rb_left;
 441                 else if (user_call_ID > call->user_call_ID)
 442                         pp = &(*pp)->rb_right;
 443                 else
 444                         goto id_in_use;
 445         }
 446
 447         /* Dequeue the first call and check it's still valid.  We gain
 448          * responsibility for the queue's reference.
 449          */
 450         call = list_entry(rx->to_be_accepted.next,
 451                           struct rxrpc_call, accept_link);
 452         list_del_init(&call->accept_link);
 453         sk_acceptq_removed(&rx->sk);
 454         rxrpc_see_call(call);
 455
 456         write_lock_bh(&call->state_lock);
 457         switch (call->state) {
 458         case RXRPC_CALL_SERVER_ACCEPTING:
 459                 call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
 460                 break;
 461         case RXRPC_CALL_COMPLETE:
 462                 ret = call->error;
 463                 goto out_release;
 464         default:
 465                 BUG();
 466         }
 467
 468         /* formalise the acceptance */
 469         rxrpc_get_call(call, rxrpc_call_got);
 470         call->notify_rx = notify_rx;
 471         call->user_call_ID = user_call_ID;
 472         rxrpc_get_call(call, rxrpc_call_got_userid);
 473         rb_link_node(&call->sock_node, parent, pp);
 474         rb_insert_color(&call->sock_node, &rx->calls);
 475         if (test_and_set_bit(RXRPC_CALL_HAS_USERID, &call->flags))
 476                 BUG();
 477
 478         write_unlock_bh(&call->state_lock);
 479         write_unlock(&rx->call_lock);
 480         rxrpc_notify_socket(call);
 481         rxrpc_service_prealloc(rx, GFP_KERNEL);
 482         _leave(" = %p{%d}", call, call->debug_id);
 483         return call;
 484
 485 out_release:
 486         _debug("release %p", call);
 487         write_unlock_bh(&call->state_lock);
 488         write_unlock(&rx->call_lock);
 489         rxrpc_release_call(rx, call);
 490         rxrpc_put_call(call, rxrpc_call_put);
 491         goto out;
 492
 493 id_in_use:
 494         ret = -EBADSLT;
 495         write_unlock(&rx->call_lock);
 496 out:
 497         rxrpc_service_prealloc(rx, GFP_KERNEL);
 498         _leave(" = %d", ret);
 499         return ERR_PTR(ret);
 500 }
 501
 502 /*
 503  * Handle rejection of a call by userspace
 504  * - reject the call at the front of the queue
 505  */
 506 int rxrpc_reject_call(struct rxrpc_sock *rx)
 507 {
 508         struct rxrpc_call *call;
 509         bool abort = false;
 510         int ret;
 511
 512         _enter("");
 513
 514         ASSERT(!irqs_disabled());
 515
 516         write_lock(&rx->call_lock);
 517
 518         if (list_empty(&rx->to_be_accepted)) {
 519                 write_unlock(&rx->call_lock);
 520                 return -ENODATA;
 521         }
 522
 523         /* Dequeue the first call and check it's still valid.  We gain
 524          * responsibility for the queue's reference.
 525          */
 526         call = list_entry(rx->to_be_accepted.next,
 527                           struct rxrpc_call, accept_link);
 528         list_del_init(&call->accept_link);
 529         sk_acceptq_removed(&rx->sk);
 530         rxrpc_see_call(call);
 531
 532         write_lock_bh(&call->state_lock);
 533         switch (call->state) {
 534         case RXRPC_CALL_SERVER_ACCEPTING:
 535                 __rxrpc_abort_call("REJ", call, 1, RX_USER_ABORT, ECONNABORTED);
 536                 abort = true;
 537                 /* fall through */
 538         case RXRPC_CALL_COMPLETE:
 539                 ret = call->error;
 540                 goto out_discard;
 541         default:
 542                 BUG();
 543         }
 544
 545 out_discard:
 546         write_unlock_bh(&call->state_lock);
 547         write_unlock(&rx->call_lock);
 548         if (abort) {
 549                 rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_ABORT);
 550                 rxrpc_release_call(rx, call);
 551                 rxrpc_put_call(call, rxrpc_call_put);
 552         }
 553         rxrpc_service_prealloc(rx, GFP_KERNEL);
 554         _leave(" = %d", ret);
 555         return ret;
 556 }
 557
 558 /*
 559  * rxrpc_kernel_charge_accept - Charge up socket with preallocated calls
 560  * @sock: The socket on which to preallocate
 561  * @notify_rx: Event notification function for the call
 562  * @user_attach_call: Func to attach call to user_call_ID
 563  * @user_call_ID: The tag to attach to the preallocated call
 564  * @gfp: The allocation conditions.
 565  *
 566  * Charge up the socket with preallocated calls, each with a user ID.  A
 567  * function should be provided to effect the attachment from the user's side.
 568  * The user is given a ref to hold on the call.
 569  *
 570  * Note that the call may be come connected before this function returns.
 571  */
 572 int rxrpc_kernel_charge_accept(struct socket *sock,
 573                                rxrpc_notify_rx_t notify_rx,
 574                                rxrpc_user_attach_call_t user_attach_call,
 575                                unsigned long user_call_ID, gfp_t gfp)
 576 {
 577         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 578         struct rxrpc_backlog *b = rx->backlog;
 579
 580         if (sock->sk->sk_state == RXRPC_CLOSE)
 581                 return -ESHUTDOWN;
 582
 583         return rxrpc_service_prealloc_one(rx, b, notify_rx,
 584                                           user_attach_call, user_call_ID,
 585                                           gfp);
 586 }
 587 EXPORT_SYMBOL(rxrpc_kernel_charge_accept);