rxrpc/call_accept.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* incoming call handling
   3  *
   4  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/module.h>
  11 #include <linux/net.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/errqueue.h>
  14 #include <linux/udp.h>
  15 #include <linux/in.h>
  16 #include <linux/in6.h>
  17 #include <linux/icmp.h>
  18 #include <linux/gfp.h>
  19 #include <linux/circ_buf.h>
  20 #include <net/sock.h>
  21 #include <net/af_rxrpc.h>
  22 #include <net/ip.h>
  23 #include "ar-internal.h"
  24
  25 static void rxrpc_dummy_notify(struct sock *sk, struct rxrpc_call *call,
  26                                unsigned long user_call_ID)
  27 {
  28 }
  29
  30 /*
  31  * Preallocate a single service call, connection and peer and, if possible,
  32  * give them a user ID and attach the user's side of the ID to them.
  33  */
  34 static int rxrpc_service_prealloc_one(struct rxrpc_sock *rx,
  35                                       struct rxrpc_backlog *b,
  36                                       rxrpc_notify_rx_t notify_rx,
  37                                       rxrpc_user_attach_call_t user_attach_call,
  38                                       unsigned long user_call_ID, gfp_t gfp,
  39                                       unsigned int debug_id)
  40 {
  41         struct rxrpc_call *call, *xcall;
  42         struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));
  43         struct rb_node *parent, **pp;
  44         int max, tmp;
  45         unsigned int size = RXRPC_BACKLOG_MAX;
  46         unsigned int head, tail, call_head, call_tail;
  47
  48         max = rx->sk.sk_max_ack_backlog;
  49         tmp = rx->sk.sk_ack_backlog;
  50         if (tmp >= max) {
  51                 _leave(" = -ENOBUFS [full %u]", max);
  52                 return -ENOBUFS;
  53         }
  54         max -= tmp;
  55
  56         /* We don't need more conns and peers than we have calls, but on the
  57          * other hand, we shouldn't ever use more peers than conns or conns
  58          * than calls.
  59          */
  60         call_head = b->call_backlog_head;
  61         call_tail = READ_ONCE(b->call_backlog_tail);
  62         tmp = CIRC_CNT(call_head, call_tail, size);
  63         if (tmp >= max) {
  64                 _leave(" = -ENOBUFS [enough %u]", tmp);
  65                 return -ENOBUFS;
  66         }
  67         max = tmp + 1;
  68
  69         head = b->peer_backlog_head;
  70         tail = READ_ONCE(b->peer_backlog_tail);
  71         if (CIRC_CNT(head, tail, size) < max) {
  72                 struct rxrpc_peer *peer;
  73
  74                 peer = rxrpc_alloc_peer(rx->local, gfp, rxrpc_peer_new_prealloc);
  75                 if (!peer)
  76                         return -ENOMEM;
  77                 b->peer_backlog[head] = peer;
  78                 smp_store_release(&b->peer_backlog_head,
  79                                   (head + 1) & (size - 1));
  80         }
  81
  82         head = b->conn_backlog_head;
  83         tail = READ_ONCE(b->conn_backlog_tail);
  84         if (CIRC_CNT(head, tail, size) < max) {
  85                 struct rxrpc_connection *conn;
  86
  87                 conn = rxrpc_prealloc_service_connection(rxnet, gfp);
  88                 if (!conn)
  89                         return -ENOMEM;
  90                 b->conn_backlog[head] = conn;
  91                 smp_store_release(&b->conn_backlog_head,
  92                                   (head + 1) & (size - 1));
  93         }
  94
  95         /* Now it gets complicated, because calls get registered with the
  96          * socket here, with a user ID preassigned by the user.
  97          */
  98         call = rxrpc_alloc_call(rx, gfp, debug_id);
  99         if (!call)
 100                 return -ENOMEM;
 101         call->flags |= (1 << RXRPC_CALL_IS_SERVICE);
 102         rxrpc_set_call_state(call, RXRPC_CALL_SERVER_PREALLOC);
 103         __set_bit(RXRPC_CALL_EV_INITIAL_PING, &call->events);
 104
 105         trace_rxrpc_call(call->debug_id, refcount_read(&call->ref),
 106                          user_call_ID, rxrpc_call_new_prealloc_service);
 107
 108         write_lock(&rx->call_lock);
 109
 110         /* Check the user ID isn't already in use */
 111         pp = &rx->calls.rb_node;
 112         parent = NULL;
 113         while (*pp) {
 114                 parent = *pp;
 115                 xcall = rb_entry(parent, struct rxrpc_call, sock_node);
 116                 if (user_call_ID < xcall->user_call_ID)
 117                         pp = &(*pp)->rb_left;
 118                 else if (user_call_ID > xcall->user_call_ID)
 119                         pp = &(*pp)->rb_right;
 120                 else
 121                         goto id_in_use;
 122         }
 123
 124         call->user_call_ID = user_call_ID;
 125         call->notify_rx = notify_rx;
 126         if (user_attach_call) {
 127                 rxrpc_get_call(call, rxrpc_call_get_kernel_service);
 128                 user_attach_call(call, user_call_ID);
 129         }
 130
 131         rxrpc_get_call(call, rxrpc_call_get_userid);
 132         rb_link_node(&call->sock_node, parent, pp);
 133         rb_insert_color(&call->sock_node, &rx->calls);
 134         set_bit(RXRPC_CALL_HAS_USERID, &call->flags);
 135
 136         list_add(&call->sock_link, &rx->sock_calls);
 137
 138         write_unlock(&rx->call_lock);
 139
 140         rxnet = call->rxnet;
 141         spin_lock(&rxnet->call_lock);
 142         list_add_tail_rcu(&call->link, &rxnet->calls);
 143         spin_unlock(&rxnet->call_lock);
 144
 145         b->call_backlog[call_head] = call;
 146         smp_store_release(&b->call_backlog_head, (call_head + 1) & (size - 1));
 147         _leave(" = 0 [%d -> %lx]", call->debug_id, user_call_ID);
 148         return 0;
 149
 150 id_in_use:
 151         write_unlock(&rx->call_lock);
 152         rxrpc_cleanup_call(call);
 153         _leave(" = -EBADSLT");
 154         return -EBADSLT;
 155 }
 156
 157 /*
 158  * Allocate the preallocation buffers for incoming service calls.  These must
 159  * be charged manually.
 160  */
 161 int rxrpc_service_prealloc(struct rxrpc_sock *rx, gfp_t gfp)
 162 {
 163         struct rxrpc_backlog *b = rx->backlog;
 164
 165         if (!b) {
 166                 b = kzalloc(sizeof(struct rxrpc_backlog), gfp);
 167                 if (!b)
 168                         return -ENOMEM;
 169                 rx->backlog = b;
 170         }
 171
 172         return 0;
 173 }
 174
 175 /*
 176  * Discard the preallocation on a service.
 177  */
 178 void rxrpc_discard_prealloc(struct rxrpc_sock *rx)
 179 {
 180         struct rxrpc_backlog *b = rx->backlog;
 181         struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));
 182         unsigned int size = RXRPC_BACKLOG_MAX, head, tail;
 183
 184         if (!b)
 185                 return;
 186         rx->backlog = NULL;
 187
 188         /* Make sure that there aren't any incoming calls in progress before we
 189          * clear the preallocation buffers.
 190          */
 191         spin_lock(&rx->incoming_lock);
 192         spin_unlock(&rx->incoming_lock);
 193
 194         head = b->peer_backlog_head;
 195         tail = b->peer_backlog_tail;
 196         while (CIRC_CNT(head, tail, size) > 0) {
 197                 struct rxrpc_peer *peer = b->peer_backlog[tail];
 198                 rxrpc_put_local(peer->local, rxrpc_local_put_prealloc_peer);
 199                 kfree(peer);
 200                 tail = (tail + 1) & (size - 1);
 201         }
 202
 203         head = b->conn_backlog_head;
 204         tail = b->conn_backlog_tail;
 205         while (CIRC_CNT(head, tail, size) > 0) {
 206                 struct rxrpc_connection *conn = b->conn_backlog[tail];
 207                 write_lock(&rxnet->conn_lock);
 208                 list_del(&conn->link);
 209                 list_del(&conn->proc_link);
 210                 write_unlock(&rxnet->conn_lock);
 211                 kfree(conn);
 212                 if (atomic_dec_and_test(&rxnet->nr_conns))
 213                         wake_up_var(&rxnet->nr_conns);
 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                 rcu_assign_pointer(call->socket, rx);
 222                 if (rx->discard_new_call) {
 223                         _debug("discard %lx", call->user_call_ID);
 224                         rx->discard_new_call(call, call->user_call_ID);
 225                         if (call->notify_rx)
 226                                 call->notify_rx = rxrpc_dummy_notify;
 227                         rxrpc_put_call(call, rxrpc_call_put_kernel);
 228                 }
 229                 rxrpc_call_completed(call);
 230                 rxrpc_release_call(rx, call);
 231                 rxrpc_put_call(call, rxrpc_call_put_discard_prealloc);
 232                 tail = (tail + 1) & (size - 1);
 233         }
 234
 235         kfree(b);
 236 }
 237
 238 /*
 239  * Allocate a new incoming call from the prealloc pool, along with a connection
 240  * and a peer as necessary.
 241  */
 242 static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx,
 243                                                     struct rxrpc_local *local,
 244                                                     struct rxrpc_peer *peer,
 245                                                     struct rxrpc_connection *conn,
 246                                                     const struct rxrpc_security *sec,
 247                                                     struct sockaddr_rxrpc *peer_srx,
 248                                                     struct sk_buff *skb)
 249 {
 250         struct rxrpc_backlog *b = rx->backlog;
 251         struct rxrpc_call *call;
 252         unsigned short call_head, conn_head, peer_head;
 253         unsigned short call_tail, conn_tail, peer_tail;
 254         unsigned short call_count, conn_count;
 255
 256         /* #calls >= #conns >= #peers must hold true. */
 257         call_head = smp_load_acquire(&b->call_backlog_head);
 258         call_tail = b->call_backlog_tail;
 259         call_count = CIRC_CNT(call_head, call_tail, RXRPC_BACKLOG_MAX);
 260         conn_head = smp_load_acquire(&b->conn_backlog_head);
 261         conn_tail = b->conn_backlog_tail;
 262         conn_count = CIRC_CNT(conn_head, conn_tail, RXRPC_BACKLOG_MAX);
 263         ASSERTCMP(conn_count, >=, call_count);
 264         peer_head = smp_load_acquire(&b->peer_backlog_head);
 265         peer_tail = b->peer_backlog_tail;
 266         ASSERTCMP(CIRC_CNT(peer_head, peer_tail, RXRPC_BACKLOG_MAX), >=,
 267                   conn_count);
 268
 269         if (call_count == 0)
 270                 return NULL;
 271
 272         if (!conn) {
 273                 if (peer && !rxrpc_get_peer_maybe(peer, rxrpc_peer_get_service_conn))
 274                         peer = NULL;
 275                 if (!peer) {
 276                         peer = b->peer_backlog[peer_tail];
 277                         peer->srx = *peer_srx;
 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                         rxrpc_new_incoming_peer(local, peer);
 284                 }
 285
 286                 /* Now allocate and set up the connection */
 287                 conn = b->conn_backlog[conn_tail];
 288                 b->conn_backlog[conn_tail] = NULL;
 289                 smp_store_release(&b->conn_backlog_tail,
 290                                   (conn_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
 291                 conn->local = rxrpc_get_local(local, rxrpc_local_get_prealloc_conn);
 292                 conn->peer = peer;
 293                 rxrpc_see_connection(conn, rxrpc_conn_see_new_service_conn);
 294                 rxrpc_new_incoming_connection(rx, conn, sec, skb);
 295         } else {
 296                 rxrpc_get_connection(conn, rxrpc_conn_get_service_conn);
 297                 atomic_inc(&conn->active);
 298         }
 299
 300         /* And now we can allocate and set up a new call */
 301         call = b->call_backlog[call_tail];
 302         b->call_backlog[call_tail] = NULL;
 303         smp_store_release(&b->call_backlog_tail,
 304                           (call_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
 305
 306         rxrpc_see_call(call, rxrpc_call_see_accept);
 307         call->local = rxrpc_get_local(conn->local, rxrpc_local_get_call);
 308         call->conn = conn;
 309         call->security = conn->security;
 310         call->security_ix = conn->security_ix;
 311         call->peer = rxrpc_get_peer(conn->peer, rxrpc_peer_get_accept);
 312         call->dest_srx = peer->srx;
 313         call->cong_ssthresh = call->peer->cong_ssthresh;
 314         call->tx_last_sent = ktime_get_real();
 315         return call;
 316 }
 317
 318 /*
 319  * Set up a new incoming call.  Called from the I/O thread.
 320  *
 321  * If this is for a kernel service, when we allocate the call, it will have
 322  * three refs on it: (1) the kernel service, (2) the user_call_ID tree, (3) the
 323  * retainer ref obtained from the backlog buffer.  Prealloc calls for userspace
 324  * services only have the ref from the backlog buffer.
 325  *
 326  * If we want to report an error, we mark the skb with the packet type and
 327  * abort code and return false.
 328  */
 329 bool rxrpc_new_incoming_call(struct rxrpc_local *local,
 330                              struct rxrpc_peer *peer,
 331                              struct rxrpc_connection *conn,
 332                              struct sockaddr_rxrpc *peer_srx,
 333                              struct sk_buff *skb)
 334 {
 335         const struct rxrpc_security *sec = NULL;
 336         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 337         struct rxrpc_call *call = NULL;
 338         struct rxrpc_sock *rx;
 339
 340         _enter("");
 341
 342         /* Don't set up a call for anything other than a DATA packet. */
 343         if (sp->hdr.type != RXRPC_PACKET_TYPE_DATA)
 344                 return rxrpc_protocol_error(skb, rxrpc_eproto_no_service_call);
 345
 346         read_lock(&local->services_lock);
 347
 348         /* Weed out packets to services we're not offering.  Packets that would
 349          * begin a call are explicitly rejected and the rest are just
 350          * discarded.
 351          */
 352         rx = local->service;
 353         if (!rx || (sp->hdr.serviceId != rx->srx.srx_service &&
 354                     sp->hdr.serviceId != rx->second_service)
 355             ) {
 356                 if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
 357                     sp->hdr.seq == 1)
 358                         goto unsupported_service;
 359                 goto discard;
 360         }
 361
 362         if (!conn) {
 363                 sec = rxrpc_get_incoming_security(rx, skb);
 364                 if (!sec)
 365                         goto unsupported_security;
 366         }
 367
 368         spin_lock(&rx->incoming_lock);
 369         if (rx->sk.sk_state == RXRPC_SERVER_LISTEN_DISABLED ||
 370             rx->sk.sk_state == RXRPC_CLOSE) {
 371                 rxrpc_direct_abort(skb, rxrpc_abort_shut_down,
 372                                    RX_INVALID_OPERATION, -ESHUTDOWN);
 373                 goto no_call;
 374         }
 375
 376         call = rxrpc_alloc_incoming_call(rx, local, peer, conn, sec, peer_srx,
 377                                          skb);
 378         if (!call) {
 379                 skb->mark = RXRPC_SKB_MARK_REJECT_BUSY;
 380                 goto no_call;
 381         }
 382
 383         trace_rxrpc_receive(call, rxrpc_receive_incoming,
 384                             sp->hdr.serial, sp->hdr.seq);
 385
 386         /* Make the call live. */
 387         rxrpc_incoming_call(rx, call, skb);
 388         conn = call->conn;
 389
 390         if (rx->notify_new_call)
 391                 rx->notify_new_call(&rx->sk, call, call->user_call_ID);
 392
 393         spin_lock(&conn->state_lock);
 394         if (conn->state == RXRPC_CONN_SERVICE_UNSECURED) {
 395                 conn->state = RXRPC_CONN_SERVICE_CHALLENGING;
 396                 set_bit(RXRPC_CONN_EV_CHALLENGE, &call->conn->events);
 397                 rxrpc_queue_conn(call->conn, rxrpc_conn_queue_challenge);
 398         }
 399         spin_unlock(&conn->state_lock);
 400
 401         spin_unlock(&rx->incoming_lock);
 402         read_unlock(&local->services_lock);
 403
 404         if (hlist_unhashed(&call->error_link)) {
 405                 spin_lock(&call->peer->lock);
 406                 hlist_add_head(&call->error_link, &call->peer->error_targets);
 407                 spin_unlock(&call->peer->lock);
 408         }
 409
 410         _leave(" = %p{%d}", call, call->debug_id);
 411         rxrpc_input_call_event(call, skb);
 412         rxrpc_put_call(call, rxrpc_call_put_input);
 413         return true;
 414
 415 unsupported_service:
 416         read_unlock(&local->services_lock);
 417         return rxrpc_direct_abort(skb, rxrpc_abort_service_not_offered,
 418                                   RX_INVALID_OPERATION, -EOPNOTSUPP);
 419 unsupported_security:
 420         read_unlock(&local->services_lock);
 421         return rxrpc_direct_abort(skb, rxrpc_abort_service_not_offered,
 422                                   RX_INVALID_OPERATION, -EKEYREJECTED);
 423 no_call:
 424         spin_unlock(&rx->incoming_lock);
 425         read_unlock(&local->services_lock);
 426         _leave(" = f [%u]", skb->mark);
 427         return false;
 428 discard:
 429         read_unlock(&local->services_lock);
 430         return true;
 431 }
 432
 433 /*
 434  * Charge up socket with preallocated calls, attaching user call IDs.
 435  */
 436 int rxrpc_user_charge_accept(struct rxrpc_sock *rx, unsigned long user_call_ID)
 437 {
 438         struct rxrpc_backlog *b = rx->backlog;
 439
 440         if (rx->sk.sk_state == RXRPC_CLOSE)
 441                 return -ESHUTDOWN;
 442
 443         return rxrpc_service_prealloc_one(rx, b, NULL, NULL, user_call_ID,
 444                                           GFP_KERNEL,
 445                                           atomic_inc_return(&rxrpc_debug_id));
 446 }
 447
 448 /*
 449  * rxrpc_kernel_charge_accept - Charge up socket with preallocated calls
 450  * @sock: The socket on which to preallocate
 451  * @notify_rx: Event notification function for the call
 452  * @user_attach_call: Func to attach call to user_call_ID
 453  * @user_call_ID: The tag to attach to the preallocated call
 454  * @gfp: The allocation conditions.
 455  * @debug_id: The tracing debug ID.
 456  *
 457  * Charge up the socket with preallocated calls, each with a user ID.  A
 458  * function should be provided to effect the attachment from the user's side.
 459  * The user is given a ref to hold on the call.
 460  *
 461  * Note that the call may be come connected before this function returns.
 462  */
 463 int rxrpc_kernel_charge_accept(struct socket *sock,
 464                                rxrpc_notify_rx_t notify_rx,
 465                                rxrpc_user_attach_call_t user_attach_call,
 466                                unsigned long user_call_ID, gfp_t gfp,
 467                                unsigned int debug_id)
 468 {
 469         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 470         struct rxrpc_backlog *b = rx->backlog;
 471
 472         if (sock->sk->sk_state == RXRPC_CLOSE)
 473                 return -ESHUTDOWN;
 474
 475         return rxrpc_service_prealloc_one(rx, b, notify_rx,
 476                                           user_attach_call, user_call_ID,
 477                                           gfp, debug_id);
 478 }
 479 EXPORT_SYMBOL(rxrpc_kernel_charge_accept);