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
  27 /**
  28  *      llc_alloc_frame - allocates sk_buff for frame
  29  *      @dev: network device this skb will be sent over
  30  *
  31  *      Allocates an sk_buff for frame and initializes sk_buff fields.
  32  *      Returns allocated skb or %NULL when out of memory.
  33  */
  34 struct sk_buff *llc_alloc_frame(struct sock *sk, struct net_device *dev)
  35 {
  36         struct sk_buff *skb = alloc_skb(128, GFP_ATOMIC);
  37
  38         if (skb) {
  39                 skb_reset_mac_header(skb);
  40                 skb_reserve(skb, 50);
  41                 skb_reset_network_header(skb);
  42                 skb_reset_transport_header(skb);
  43                 skb->protocol = htons(ETH_P_802_2);
  44                 skb->dev      = dev;
  45                 if (sk != NULL)
  46                         skb_set_owner_w(skb, sk);
  47         }
  48         return skb;
  49 }
  50
  51 void llc_save_primitive(struct sock *sk, struct sk_buff* skb, u8 prim)
  52 {
  53         struct sockaddr_llc *addr;
  54
  55        /* save primitive for use by the user. */
  56         addr              = llc_ui_skb_cb(skb);
  57
  58         memset(addr, 0, sizeof(*addr));
  59         addr->sllc_family = sk->sk_family;
  60         addr->sllc_arphrd = skb->dev->type;
  61         addr->sllc_test   = prim == LLC_TEST_PRIM;
  62         addr->sllc_xid    = prim == LLC_XID_PRIM;
  63         addr->sllc_ua     = prim == LLC_DATAUNIT_PRIM;
  64         llc_pdu_decode_sa(skb, addr->sllc_mac);
  65         llc_pdu_decode_ssap(skb, &addr->sllc_sap);
  66 }
  67
  68 /**
  69  *      llc_sap_rtn_pdu - Informs upper layer on rx of an UI, XID or TEST pdu.
  70  *      @sap: pointer to SAP
  71  *      @skb: received pdu
  72  */
  73 void llc_sap_rtn_pdu(struct llc_sap *sap, struct sk_buff *skb)
  74 {
  75         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
  76         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
  77
  78         switch (LLC_U_PDU_RSP(pdu)) {
  79         case LLC_1_PDU_CMD_TEST:
  80                 ev->prim = LLC_TEST_PRIM;       break;
  81         case LLC_1_PDU_CMD_XID:
  82                 ev->prim = LLC_XID_PRIM;        break;
  83         case LLC_1_PDU_CMD_UI:
  84                 ev->prim = LLC_DATAUNIT_PRIM;   break;
  85         }
  86         ev->ind_cfm_flag = LLC_IND;
  87 }
  88
  89 /**
  90  *      llc_find_sap_trans - finds transition for event
  91  *      @sap: pointer to SAP
  92  *      @skb: happened event
  93  *
  94  *      This function finds transition that matches with happened event.
  95  *      Returns the pointer to found transition on success or %NULL for
  96  *      failure.
  97  */
  98 static struct llc_sap_state_trans *llc_find_sap_trans(struct llc_sap *sap,
  99                                                       struct sk_buff* skb)
 100 {
 101         int i = 0;
 102         struct llc_sap_state_trans *rc = NULL;
 103         struct llc_sap_state_trans **next_trans;
 104         struct llc_sap_state *curr_state = &llc_sap_state_table[sap->state - 1];
 105         /*
 106          * Search thru events for this state until list exhausted or until
 107          * its obvious the event is not valid for the current state
 108          */
 109         for (next_trans = curr_state->transitions; next_trans[i]->ev; i++)
 110                 if (!next_trans[i]->ev(sap, skb)) {
 111                         rc = next_trans[i]; /* got event match; return it */
 112                         break;
 113                 }
 114         return rc;
 115 }
 116
 117 /**
 118  *      llc_exec_sap_trans_actions - execute actions related to event
 119  *      @sap: pointer to SAP
 120  *      @trans: pointer to transition that it's actions must be performed
 121  *      @skb: happened event.
 122  *
 123  *      This function executes actions that is related to happened event.
 124  *      Returns 0 for success and 1 for failure of at least one action.
 125  */
 126 static int llc_exec_sap_trans_actions(struct llc_sap *sap,
 127                                       struct llc_sap_state_trans *trans,
 128                                       struct sk_buff *skb)
 129 {
 130         int rc = 0;
 131         llc_sap_action_t *next_action = trans->ev_actions;
 132
 133         for (; next_action && *next_action; next_action++)
 134                 if ((*next_action)(sap, skb))
 135                         rc = 1;
 136         return rc;
 137 }
 138
 139 /**
 140  *      llc_sap_next_state - finds transition, execs actions & change SAP state
 141  *      @sap: pointer to SAP
 142  *      @skb: happened event
 143  *
 144  *      This function finds transition that matches with happened event, then
 145  *      executes related actions and finally changes state of SAP. It returns
 146  *      0 on success and 1 for failure.
 147  */
 148 static int llc_sap_next_state(struct llc_sap *sap, struct sk_buff *skb)
 149 {
 150         int rc = 1;
 151         struct llc_sap_state_trans *trans;
 152
 153         if (sap->state > LLC_NR_SAP_STATES)
 154                 goto out;
 155         trans = llc_find_sap_trans(sap, skb);
 156         if (!trans)
 157                 goto out;
 158         /*
 159          * Got the state to which we next transition; perform the actions
 160          * associated with this transition before actually transitioning to the
 161          * next state
 162          */
 163         rc = llc_exec_sap_trans_actions(sap, trans, skb);
 164         if (rc)
 165                 goto out;
 166         /*
 167          * Transition SAP to next state if all actions execute successfully
 168          */
 169         sap->state = trans->next_state;
 170 out:
 171         return rc;
 172 }
 173
 174 /**
 175  *      llc_sap_state_process - sends event to SAP state machine
 176  *      @sap: sap to use
 177  *      @skb: pointer to occurred event
 178  *
 179  *      After executing actions of the event, upper layer will be indicated
 180  *      if needed(on receiving an UI frame). sk can be null for the
 181  *      datalink_proto case.
 182  */
 183 static void llc_sap_state_process(struct llc_sap *sap, struct sk_buff *skb)
 184 {
 185         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
 186
 187         /*
 188          * We have to hold the skb, because llc_sap_next_state
 189          * will kfree it in the sending path and we need to
 190          * look at the skb->cb, where we encode llc_sap_state_ev.
 191          */
 192         skb_get(skb);
 193         ev->ind_cfm_flag = 0;
 194         llc_sap_next_state(sap, skb);
 195         if (ev->ind_cfm_flag == LLC_IND) {
 196                 if (skb->sk->sk_state == TCP_LISTEN)
 197                         kfree_skb(skb);
 198                 else {
 199                         llc_save_primitive(skb->sk, skb, ev->prim);
 200
 201                         /* queue skb to the user. */
 202                         if (sock_queue_rcv_skb(skb->sk, skb))
 203                                 kfree_skb(skb);
 204                 }
 205         }
 206         kfree_skb(skb);
 207 }
 208
 209 /**
 210  *      llc_build_and_send_test_pkt - TEST interface for upper layers.
 211  *      @sap: sap to use
 212  *      @skb: packet to send
 213  *      @dmac: destination mac address
 214  *      @dsap: destination sap
 215  *
 216  *      This function is called when upper layer wants to send a TEST pdu.
 217  *      Returns 0 for success, 1 otherwise.
 218  */
 219 void llc_build_and_send_test_pkt(struct llc_sap *sap,
 220                                  struct sk_buff *skb, u8 *dmac, u8 dsap)
 221 {
 222         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
 223
 224         ev->saddr.lsap = sap->laddr.lsap;
 225         ev->daddr.lsap = dsap;
 226         memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
 227         memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
 228
 229         ev->type      = LLC_SAP_EV_TYPE_PRIM;
 230         ev->prim      = LLC_TEST_PRIM;
 231         ev->prim_type = LLC_PRIM_TYPE_REQ;
 232         llc_sap_state_process(sap, skb);
 233 }
 234
 235 /**
 236  *      llc_build_and_send_xid_pkt - XID interface for upper layers
 237  *      @sap: sap to use
 238  *      @skb: packet to send
 239  *      @dmac: destination mac address
 240  *      @dsap: destination sap
 241  *
 242  *      This function is called when upper layer wants to send a XID pdu.
 243  *      Returns 0 for success, 1 otherwise.
 244  */
 245 void llc_build_and_send_xid_pkt(struct llc_sap *sap, struct sk_buff *skb,
 246                                 u8 *dmac, u8 dsap)
 247 {
 248         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
 249
 250         ev->saddr.lsap = sap->laddr.lsap;
 251         ev->daddr.lsap = dsap;
 252         memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
 253         memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
 254
 255         ev->type      = LLC_SAP_EV_TYPE_PRIM;
 256         ev->prim      = LLC_XID_PRIM;
 257         ev->prim_type = LLC_PRIM_TYPE_REQ;
 258         llc_sap_state_process(sap, skb);
 259 }
 260
 261 /**
 262  *      llc_sap_rcv - sends received pdus to the sap state machine
 263  *      @sap: current sap component structure.
 264  *      @skb: received frame.
 265  *
 266  *      Sends received pdus to the sap state machine.
 267  */
 268 static void llc_sap_rcv(struct llc_sap *sap, struct sk_buff *skb)
 269 {
 270         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
 271
 272         ev->type   = LLC_SAP_EV_TYPE_PDU;
 273         ev->reason = 0;
 274         llc_sap_state_process(sap, skb);
 275 }
 276
 277 /**
 278  *      llc_lookup_dgram - Finds dgram socket for the local sap/mac
 279  *      @sap: SAP
 280  *      @laddr: address of local LLC (MAC + SAP)
 281  *
 282  *      Search socket list of the SAP and finds connection using the local
 283  *      mac, and local sap. Returns pointer for socket found, %NULL otherwise.
 284  */
 285 static struct sock *llc_lookup_dgram(struct llc_sap *sap,
 286                                      const struct llc_addr *laddr)
 287 {
 288         struct sock *rc;
 289         struct hlist_node *node;
 290
 291         read_lock_bh(&sap->sk_list.lock);
 292         sk_for_each(rc, node, &sap->sk_list.list) {
 293                 struct llc_sock *llc = llc_sk(rc);
 294
 295                 if (rc->sk_type == SOCK_DGRAM &&
 296                     llc->laddr.lsap == laddr->lsap &&
 297                     llc_mac_match(llc->laddr.mac, laddr->mac)) {
 298                         sock_hold(rc);
 299                         goto found;
 300                 }
 301         }
 302         rc = NULL;
 303 found:
 304         read_unlock_bh(&sap->sk_list.lock);
 305         return rc;
 306 }
 307
 308 /**
 309  *      llc_sap_mcast - Deliver multicast PDU's to all matching datagram sockets.
 310  *      @sap: SAP
 311  *      @laddr: address of local LLC (MAC + SAP)
 312  *
 313  *      Search socket list of the SAP and finds connections with same sap.
 314  *      Deliver clone to each.
 315  */
 316 static void llc_sap_mcast(struct llc_sap *sap,
 317                           const struct llc_addr *laddr,
 318                           struct sk_buff *skb)
 319 {
 320         struct sock *sk;
 321         struct hlist_node *node;
 322
 323         read_lock_bh(&sap->sk_list.lock);
 324         sk_for_each(sk, node, &sap->sk_list.list) {
 325                 struct llc_sock *llc = llc_sk(sk);
 326                 struct sk_buff *skb1;
 327
 328                 if (sk->sk_type != SOCK_DGRAM)
 329                         continue;
 330
 331                 if (llc->laddr.lsap != laddr->lsap)
 332                         continue;
 333
 334                 if (llc->dev != skb->dev)
 335                         continue;
 336
 337                 skb1 = skb_clone(skb, GFP_ATOMIC);
 338                 if (!skb1)
 339                         break;
 340
 341                 sock_hold(sk);
 342                 skb_set_owner_r(skb1, sk);
 343                 llc_sap_rcv(sap, skb1);
 344                 sock_put(sk);
 345         }
 346         read_unlock_bh(&sap->sk_list.lock);
 347 }
 348
 349
 350 void llc_sap_handler(struct llc_sap *sap, struct sk_buff *skb)
 351 {
 352         struct llc_addr laddr;
 353
 354         llc_pdu_decode_da(skb, laddr.mac);
 355         llc_pdu_decode_dsap(skb, &laddr.lsap);
 356
 357         if (llc_mac_multicast(laddr.mac)) {
 358                 llc_sap_mcast(sap, &laddr, skb);
 359                 kfree_skb(skb);
 360         } else {
 361                 struct sock *sk = llc_lookup_dgram(sap, &laddr);
 362                 if (sk) {
 363                         skb_set_owner_r(skb, sk);
 364                         llc_sap_rcv(sap, skb);
 365                         sock_put(sk);
 366                 } else
 367                         kfree_skb(skb);
 368         }
 369 }