net/llc/llc_sap.c

   1 /*
   2  * llc_sap.c - driver routines for SAP component.
   3  *
   4  * Copyright (c) 1997 by Procom Technology, Inc.
   5  *               2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   6  *
   7  * This program can be redistributed or modified under the terms of the
   8  * GNU General Public License as published by the Free Software Foundation.
   9  * This program is distributed without any warranty or implied warranty
  10  * of merchantability or fitness for a particular purpose.
  11  *
  12  * See the GNU General Public License for more details.
  13  */
  14
  15 #include <net/llc.h>
  16 #include <net/llc_if.h>
  17 #include <net/llc_conn.h>
  18 #include <net/llc_pdu.h>
  19 #include <net/llc_sap.h>
  20 #include <net/llc_s_ac.h>
  21 #include <net/llc_s_ev.h>
  22 #include <net/llc_s_st.h>
  23 #include <net/sock.h>
  24 #include <net/tcp_states.h>
  25 #include <linux/llc.h>
  26 #include <linux/slab.h>
  27
  28 static int llc_mac_header_len(unsigned short devtype)
  29 {
  30         switch (devtype) {
  31         case ARPHRD_ETHER:
  32         case ARPHRD_LOOPBACK:
  33                 return sizeof(struct ethhdr);
  34         }
  35         return 0;
  36 }
  37
  38 /**
  39  *      llc_alloc_frame - allocates sk_buff for frame
  40  *      @sk:  socket to allocate frame to
  41  *      @dev: network device this skb will be sent over
  42  *      @type: pdu type to allocate
  43  *      @data_size: data size to allocate
  44  *
  45  *      Allocates an sk_buff for frame and initializes sk_buff fields.
  46  *      Returns allocated skb or %NULL when out of memory.
  47  */
  48 struct sk_buff *llc_alloc_frame(struct sock *sk, struct net_device *dev,
  49                                 u8 type, u32 data_size)
  50 {
  51         int hlen = type == LLC_PDU_TYPE_U ? 3 : 4;
  52         struct sk_buff *skb;
  53
  54         hlen += llc_mac_header_len(dev->type);
  55         skb = alloc_skb(hlen + data_size, GFP_ATOMIC);
  56
  57         if (skb) {
  58                 skb_reset_mac_header(skb);
  59                 skb_reserve(skb, hlen);
  60                 skb_reset_network_header(skb);
  61                 skb_reset_transport_header(skb);
  62                 skb->protocol = htons(ETH_P_802_2);
  63                 skb->dev      = dev;
  64                 if (sk != NULL)
  65                         skb_set_owner_w(skb, sk);
  66         }
  67         return skb;
  68 }
  69
  70 void llc_save_primitive(struct sock *sk, struct sk_buff *skb, u8 prim)
  71 {
  72         struct sockaddr_llc *addr;
  73
  74        /* save primitive for use by the user. */
  75         addr              = llc_ui_skb_cb(skb);
  76
  77         memset(addr, 0, sizeof(*addr));
  78         addr->sllc_family = sk->sk_family;
  79         addr->sllc_arphrd = skb->dev->type;
  80         addr->sllc_test   = prim == LLC_TEST_PRIM;
  81         addr->sllc_xid    = prim == LLC_XID_PRIM;
  82         addr->sllc_ua     = prim == LLC_DATAUNIT_PRIM;
  83         llc_pdu_decode_sa(skb, addr->sllc_mac);
  84         llc_pdu_decode_ssap(skb, &addr->sllc_sap);
  85 }
  86
  87 /**
  88  *      llc_sap_rtn_pdu - Informs upper layer on rx of an UI, XID or TEST pdu.
  89  *      @sap: pointer to SAP
  90  *      @skb: received pdu
  91  */
  92 void llc_sap_rtn_pdu(struct llc_sap *sap, struct sk_buff *skb)
  93 {
  94         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
  95         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
  96
  97         switch (LLC_U_PDU_RSP(pdu)) {
  98         case LLC_1_PDU_CMD_TEST:
  99                 ev->prim = LLC_TEST_PRIM;       break;
 100         case LLC_1_PDU_CMD_XID:
 101                 ev->prim = LLC_XID_PRIM;        break;
 102         case LLC_1_PDU_CMD_UI:
 103                 ev->prim = LLC_DATAUNIT_PRIM;   break;
 104         }
 105         ev->ind_cfm_flag = LLC_IND;
 106 }
 107
 108 /**
 109  *      llc_find_sap_trans - finds transition for event
 110  *      @sap: pointer to SAP
 111  *      @skb: happened event
 112  *
 113  *      This function finds transition that matches with happened event.
 114  *      Returns the pointer to found transition on success or %NULL for
 115  *      failure.
 116  */
 117 static struct llc_sap_state_trans *llc_find_sap_trans(struct llc_sap *sap,
 118                                                       struct sk_buff *skb)
 119 {
 120         int i = 0;
 121         struct llc_sap_state_trans *rc = NULL;
 122         struct llc_sap_state_trans **next_trans;
 123         struct llc_sap_state *curr_state = &llc_sap_state_table[sap->state - 1];
 124         /*
 125          * Search thru events for this state until list exhausted or until
 126          * its obvious the event is not valid for the current state
 127          */
 128         for (next_trans = curr_state->transitions; next_trans[i]->ev; i++)
 129                 if (!next_trans[i]->ev(sap, skb)) {
 130                         rc = next_trans[i]; /* got event match; return it */
 131                         break;
 132                 }
 133         return rc;
 134 }
 135
 136 /**
 137  *      llc_exec_sap_trans_actions - execute actions related to event
 138  *      @sap: pointer to SAP
 139  *      @trans: pointer to transition that it's actions must be performed
 140  *      @skb: happened event.
 141  *
 142  *      This function executes actions that is related to happened event.
 143  *      Returns 0 for success and 1 for failure of at least one action.
 144  */
 145 static int llc_exec_sap_trans_actions(struct llc_sap *sap,
 146                                       struct llc_sap_state_trans *trans,
 147                                       struct sk_buff *skb)
 148 {
 149         int rc = 0;
 150         const llc_sap_action_t *next_action = trans->ev_actions;
 151
 152         for (; next_action && *next_action; next_action++)
 153                 if ((*next_action)(sap, skb))
 154                         rc = 1;
 155         return rc;
 156 }
 157
 158 /**
 159  *      llc_sap_next_state - finds transition, execs actions & change SAP state
 160  *      @sap: pointer to SAP
 161  *      @skb: happened event
 162  *
 163  *      This function finds transition that matches with happened event, then
 164  *      executes related actions and finally changes state of SAP. It returns
 165  *      0 on success and 1 for failure.
 166  */
 167 static int llc_sap_next_state(struct llc_sap *sap, struct sk_buff *skb)
 168 {
 169         int rc = 1;
 170         struct llc_sap_state_trans *trans;
 171
 172         if (sap->state > LLC_NR_SAP_STATES)
 173                 goto out;
 174         trans = llc_find_sap_trans(sap, skb);
 175         if (!trans)
 176                 goto out;
 177         /*
 178          * Got the state to which we next transition; perform the actions
 179          * associated with this transition before actually transitioning to the
 180          * next state
 181          */
 182         rc = llc_exec_sap_trans_actions(sap, trans, skb);
 183         if (rc)
 184                 goto out;
 185         /*
 186          * Transition SAP to next state if all actions execute successfully
 187          */
 188         sap->state = trans->next_state;
 189 out:
 190         return rc;
 191 }
 192
 193 /**
 194  *      llc_sap_state_process - sends event to SAP state machine
 195  *      @sap: sap to use
 196  *      @skb: pointer to occurred event
 197  *
 198  *      After executing actions of the event, upper layer will be indicated
 199  *      if needed(on receiving an UI frame). sk can be null for the
 200  *      datalink_proto case.
 201  *
 202  *      This function always consumes a reference to the skb.
 203  */
 204 static void llc_sap_state_process(struct llc_sap *sap, struct sk_buff *skb)
 205 {
 206         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
 207
 208         ev->ind_cfm_flag = 0;
 209         llc_sap_next_state(sap, skb);
 210
 211         if (ev->ind_cfm_flag == LLC_IND && skb->sk->sk_state != TCP_LISTEN) {
 212                 llc_save_primitive(skb->sk, skb, ev->prim);
 213
 214                 /* queue skb to the user. */
 215                 if (sock_queue_rcv_skb(skb->sk, skb) == 0)
 216                         return;
 217         }
 218         kfree_skb(skb);
 219 }
 220
 221 /**
 222  *      llc_build_and_send_test_pkt - TEST interface for upper layers.
 223  *      @sap: sap to use
 224  *      @skb: packet to send
 225  *      @dmac: destination mac address
 226  *      @dsap: destination sap
 227  *
 228  *      This function is called when upper layer wants to send a TEST pdu.
 229  *      Returns 0 for success, 1 otherwise.
 230  */
 231 void llc_build_and_send_test_pkt(struct llc_sap *sap,
 232                                  struct sk_buff *skb, u8 *dmac, u8 dsap)
 233 {
 234         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
 235
 236         ev->saddr.lsap = sap->laddr.lsap;
 237         ev->daddr.lsap = dsap;
 238         memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
 239         memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
 240
 241         ev->type      = LLC_SAP_EV_TYPE_PRIM;
 242         ev->prim      = LLC_TEST_PRIM;
 243         ev->prim_type = LLC_PRIM_TYPE_REQ;
 244         llc_sap_state_process(sap, skb);
 245 }
 246
 247 /**
 248  *      llc_build_and_send_xid_pkt - XID interface for upper layers
 249  *      @sap: sap to use
 250  *      @skb: packet to send
 251  *      @dmac: destination mac address
 252  *      @dsap: destination sap
 253  *
 254  *      This function is called when upper layer wants to send a XID pdu.
 255  *      Returns 0 for success, 1 otherwise.
 256  */
 257 void llc_build_and_send_xid_pkt(struct llc_sap *sap, struct sk_buff *skb,
 258                                 u8 *dmac, u8 dsap)
 259 {
 260         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
 261
 262         ev->saddr.lsap = sap->laddr.lsap;
 263         ev->daddr.lsap = dsap;
 264         memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
 265         memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
 266
 267         ev->type      = LLC_SAP_EV_TYPE_PRIM;
 268         ev->prim      = LLC_XID_PRIM;
 269         ev->prim_type = LLC_PRIM_TYPE_REQ;
 270         llc_sap_state_process(sap, skb);
 271 }
 272
 273 /**
 274  *      llc_sap_rcv - sends received pdus to the sap state machine
 275  *      @sap: current sap component structure.
 276  *      @skb: received frame.
 277  *      @sk:  socket to associate to frame
 278  *
 279  *      Sends received pdus to the sap state machine.
 280  */
 281 static void llc_sap_rcv(struct llc_sap *sap, struct sk_buff *skb,
 282                         struct sock *sk)
 283 {
 284         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
 285
 286         ev->type   = LLC_SAP_EV_TYPE_PDU;
 287         ev->reason = 0;
 288         skb_orphan(skb);
 289         sock_hold(sk);
 290         skb->sk = sk;
 291         skb->destructor = sock_efree;
 292         llc_sap_state_process(sap, skb);
 293 }
 294
 295 static inline bool llc_dgram_match(const struct llc_sap *sap,
 296                                    const struct llc_addr *laddr,
 297                                    const struct sock *sk)
 298 {
 299      struct llc_sock *llc = llc_sk(sk);
 300
 301      return sk->sk_type == SOCK_DGRAM &&
 302           llc->laddr.lsap == laddr->lsap &&
 303           ether_addr_equal(llc->laddr.mac, laddr->mac);
 304 }
 305
 306 /**
 307  *      llc_lookup_dgram - Finds dgram socket for the local sap/mac
 308  *      @sap: SAP
 309  *      @laddr: address of local LLC (MAC + SAP)
 310  *
 311  *      Search socket list of the SAP and finds connection using the local
 312  *      mac, and local sap. Returns pointer for socket found, %NULL otherwise.
 313  */
 314 static struct sock *llc_lookup_dgram(struct llc_sap *sap,
 315                                      const struct llc_addr *laddr)
 316 {
 317         struct sock *rc;
 318         struct hlist_nulls_node *node;
 319         int slot = llc_sk_laddr_hashfn(sap, laddr);
 320         struct hlist_nulls_head *laddr_hb = &sap->sk_laddr_hash[slot];
 321
 322         rcu_read_lock_bh();
 323 again:
 324         sk_nulls_for_each_rcu(rc, node, laddr_hb) {
 325                 if (llc_dgram_match(sap, laddr, rc)) {
 326                         /* Extra checks required by SLAB_TYPESAFE_BY_RCU */
 327                         if (unlikely(!refcount_inc_not_zero(&rc->sk_refcnt)))
 328                                 goto again;
 329                         if (unlikely(llc_sk(rc)->sap != sap ||
 330                                      !llc_dgram_match(sap, laddr, rc))) {
 331                                 sock_put(rc);
 332                                 continue;
 333                         }
 334                         goto found;
 335                 }
 336         }
 337         rc = NULL;
 338         /*
 339          * if the nulls value we got at the end of this lookup is
 340          * not the expected one, we must restart lookup.
 341          * We probably met an item that was moved to another chain.
 342          */
 343         if (unlikely(get_nulls_value(node) != slot))
 344                 goto again;
 345 found:
 346         rcu_read_unlock_bh();
 347         return rc;
 348 }
 349
 350 static inline bool llc_mcast_match(const struct llc_sap *sap,
 351                                    const struct llc_addr *laddr,
 352                                    const struct sk_buff *skb,
 353                                    const struct sock *sk)
 354 {
 355      struct llc_sock *llc = llc_sk(sk);
 356
 357      return sk->sk_type == SOCK_DGRAM &&
 358           llc->laddr.lsap == laddr->lsap &&
 359           llc->dev == skb->dev;
 360 }
 361
 362 static void llc_do_mcast(struct llc_sap *sap, struct sk_buff *skb,
 363                          struct sock **stack, int count)
 364 {
 365         struct sk_buff *skb1;
 366         int i;
 367
 368         for (i = 0; i < count; i++) {
 369                 skb1 = skb_clone(skb, GFP_ATOMIC);
 370                 if (!skb1) {
 371                         sock_put(stack[i]);
 372                         continue;
 373                 }
 374
 375                 llc_sap_rcv(sap, skb1, stack[i]);
 376                 sock_put(stack[i]);
 377         }
 378 }
 379
 380 /**
 381  *      llc_sap_mcast - Deliver multicast PDU's to all matching datagram sockets.
 382  *      @sap: SAP
 383  *      @laddr: address of local LLC (MAC + SAP)
 384  *      @skb: PDU to deliver
 385  *
 386  *      Search socket list of the SAP and finds connections with same sap.
 387  *      Deliver clone to each.
 388  */
 389 static void llc_sap_mcast(struct llc_sap *sap,
 390                           const struct llc_addr *laddr,
 391                           struct sk_buff *skb)
 392 {
 393         int i = 0;
 394         struct sock *sk;
 395         struct sock *stack[256 / sizeof(struct sock *)];
 396         struct llc_sock *llc;
 397         struct hlist_head *dev_hb = llc_sk_dev_hash(sap, skb->dev->ifindex);
 398
 399         spin_lock_bh(&sap->sk_lock);
 400         hlist_for_each_entry(llc, dev_hb, dev_hash_node) {
 401
 402                 sk = &llc->sk;
 403
 404                 if (!llc_mcast_match(sap, laddr, skb, sk))
 405                         continue;
 406
 407                 sock_hold(sk);
 408                 if (i < ARRAY_SIZE(stack))
 409                         stack[i++] = sk;
 410                 else {
 411                         llc_do_mcast(sap, skb, stack, i);
 412                         i = 0;
 413                 }
 414         }
 415         spin_unlock_bh(&sap->sk_lock);
 416
 417         llc_do_mcast(sap, skb, stack, i);
 418 }
 419
 420
 421 void llc_sap_handler(struct llc_sap *sap, struct sk_buff *skb)
 422 {
 423         struct llc_addr laddr;
 424
 425         llc_pdu_decode_da(skb, laddr.mac);
 426         llc_pdu_decode_dsap(skb, &laddr.lsap);
 427
 428         if (is_multicast_ether_addr(laddr.mac)) {
 429                 llc_sap_mcast(sap, &laddr, skb);
 430                 kfree_skb(skb);
 431         } else {
 432                 struct sock *sk = llc_lookup_dgram(sap, &laddr);
 433                 if (sk) {
 434                         llc_sap_rcv(sap, skb, sk);
 435                         sock_put(sk);
 436                 } else
 437                         kfree_skb(skb);
 438         }
 439 }