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 static int llc_mac_header_len(unsigned short devtype)
  28 {
  29         switch (devtype) {
  30         case ARPHRD_ETHER:
  31         case ARPHRD_LOOPBACK:
  32                 return sizeof(struct ethhdr);
  33 #ifdef CONFIG_TR
  34         case ARPHRD_IEEE802_TR:
  35                 return sizeof(struct trh_hdr);
  36 #endif
  37         }
  38         return 0;
  39 }
  40
  41 /**
  42  *      llc_alloc_frame - allocates sk_buff for frame
  43  *      @dev: network device this skb will be sent over
  44  *      @type: pdu type to allocate
  45  *      @data_size: data size to allocate
  46  *
  47  *      Allocates an sk_buff for frame and initializes sk_buff fields.
  48  *      Returns allocated skb or %NULL when out of memory.
  49  */
  50 struct sk_buff *llc_alloc_frame(struct sock *sk, struct net_device *dev,
  51                                 u8 type, u32 data_size)
  52 {
  53         int hlen = type == LLC_PDU_TYPE_U ? 3 : 4;
  54         struct sk_buff *skb;
  55
  56         hlen += llc_mac_header_len(dev->type);
  57         skb = alloc_skb(hlen + data_size, GFP_ATOMIC);
  58
  59         if (skb) {
  60                 skb_reset_mac_header(skb);
  61                 skb_reserve(skb, hlen);
  62                 skb_reset_network_header(skb);
  63                 skb_reset_transport_header(skb);
  64                 skb->protocol = htons(ETH_P_802_2);
  65                 skb->dev      = dev;
  66                 if (sk != NULL)
  67                         skb_set_owner_w(skb, sk);
  68         }
  69         return skb;
  70 }
  71
  72 void llc_save_primitive(struct sock *sk, struct sk_buff* skb, u8 prim)
  73 {
  74         struct sockaddr_llc *addr;
  75
  76        /* save primitive for use by the user. */
  77         addr              = llc_ui_skb_cb(skb);
  78
  79         memset(addr, 0, sizeof(*addr));
  80         addr->sllc_family = sk->sk_family;
  81         addr->sllc_arphrd = skb->dev->type;
  82         addr->sllc_test   = prim == LLC_TEST_PRIM;
  83         addr->sllc_xid    = prim == LLC_XID_PRIM;
  84         addr->sllc_ua     = prim == LLC_DATAUNIT_PRIM;
  85         llc_pdu_decode_sa(skb, addr->sllc_mac);
  86         llc_pdu_decode_ssap(skb, &addr->sllc_sap);
  87 }
  88
  89 /**
  90  *      llc_sap_rtn_pdu - Informs upper layer on rx of an UI, XID or TEST pdu.
  91  *      @sap: pointer to SAP
  92  *      @skb: received pdu
  93  */
  94 void llc_sap_rtn_pdu(struct llc_sap *sap, struct sk_buff *skb)
  95 {
  96         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
  97         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
  98
  99         switch (LLC_U_PDU_RSP(pdu)) {
 100         case LLC_1_PDU_CMD_TEST:
 101                 ev->prim = LLC_TEST_PRIM;       break;
 102         case LLC_1_PDU_CMD_XID:
 103                 ev->prim = LLC_XID_PRIM;        break;
 104         case LLC_1_PDU_CMD_UI:
 105                 ev->prim = LLC_DATAUNIT_PRIM;   break;
 106         }
 107         ev->ind_cfm_flag = LLC_IND;
 108 }
 109
 110 /**
 111  *      llc_find_sap_trans - finds transition for event
 112  *      @sap: pointer to SAP
 113  *      @skb: happened event
 114  *
 115  *      This function finds transition that matches with happened event.
 116  *      Returns the pointer to found transition on success or %NULL for
 117  *      failure.
 118  */
 119 static struct llc_sap_state_trans *llc_find_sap_trans(struct llc_sap *sap,
 120                                                       struct sk_buff* skb)
 121 {
 122         int i = 0;
 123         struct llc_sap_state_trans *rc = NULL;
 124         struct llc_sap_state_trans **next_trans;
 125         struct llc_sap_state *curr_state = &llc_sap_state_table[sap->state - 1];
 126         /*
 127          * Search thru events for this state until list exhausted or until
 128          * its obvious the event is not valid for the current state
 129          */
 130         for (next_trans = curr_state->transitions; next_trans[i]->ev; i++)
 131                 if (!next_trans[i]->ev(sap, skb)) {
 132                         rc = next_trans[i]; /* got event match; return it */
 133                         break;
 134                 }
 135         return rc;
 136 }
 137
 138 /**
 139  *      llc_exec_sap_trans_actions - execute actions related to event
 140  *      @sap: pointer to SAP
 141  *      @trans: pointer to transition that it's actions must be performed
 142  *      @skb: happened event.
 143  *
 144  *      This function executes actions that is related to happened event.
 145  *      Returns 0 for success and 1 for failure of at least one action.
 146  */
 147 static int llc_exec_sap_trans_actions(struct llc_sap *sap,
 148                                       struct llc_sap_state_trans *trans,
 149                                       struct sk_buff *skb)
 150 {
 151         int rc = 0;
 152         llc_sap_action_t *next_action = trans->ev_actions;
 153
 154         for (; next_action && *next_action; next_action++)
 155                 if ((*next_action)(sap, skb))
 156                         rc = 1;
 157         return rc;
 158 }
 159
 160 /**
 161  *      llc_sap_next_state - finds transition, execs actions & change SAP state
 162  *      @sap: pointer to SAP
 163  *      @skb: happened event
 164  *
 165  *      This function finds transition that matches with happened event, then
 166  *      executes related actions and finally changes state of SAP. It returns
 167  *      0 on success and 1 for failure.
 168  */
 169 static int llc_sap_next_state(struct llc_sap *sap, struct sk_buff *skb)
 170 {
 171         int rc = 1;
 172         struct llc_sap_state_trans *trans;
 173
 174         if (sap->state > LLC_NR_SAP_STATES)
 175                 goto out;
 176         trans = llc_find_sap_trans(sap, skb);
 177         if (!trans)
 178                 goto out;
 179         /*
 180          * Got the state to which we next transition; perform the actions
 181          * associated with this transition before actually transitioning to the
 182          * next state
 183          */
 184         rc = llc_exec_sap_trans_actions(sap, trans, skb);
 185         if (rc)
 186                 goto out;
 187         /*
 188          * Transition SAP to next state if all actions execute successfully
 189          */
 190         sap->state = trans->next_state;
 191 out:
 192         return rc;
 193 }
 194
 195 /**
 196  *      llc_sap_state_process - sends event to SAP state machine
 197  *      @sap: sap to use
 198  *      @skb: pointer to occurred event
 199  *
 200  *      After executing actions of the event, upper layer will be indicated
 201  *      if needed(on receiving an UI frame). sk can be null for the
 202  *      datalink_proto case.
 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         /*
 209          * We have to hold the skb, because llc_sap_next_state
 210          * will kfree it in the sending path and we need to
 211          * look at the skb->cb, where we encode llc_sap_state_ev.
 212          */
 213         skb_get(skb);
 214         ev->ind_cfm_flag = 0;
 215         llc_sap_next_state(sap, skb);
 216         if (ev->ind_cfm_flag == LLC_IND) {
 217                 if (skb->sk->sk_state == TCP_LISTEN)
 218                         kfree_skb(skb);
 219                 else {
 220                         llc_save_primitive(skb->sk, skb, ev->prim);
 221
 222                         /* queue skb to the user. */
 223                         if (sock_queue_rcv_skb(skb->sk, skb))
 224                                 kfree_skb(skb);
 225                 }
 226         }
 227         kfree_skb(skb);
 228 }
 229
 230 /**
 231  *      llc_build_and_send_test_pkt - TEST interface for upper layers.
 232  *      @sap: sap to use
 233  *      @skb: packet to send
 234  *      @dmac: destination mac address
 235  *      @dsap: destination sap
 236  *
 237  *      This function is called when upper layer wants to send a TEST pdu.
 238  *      Returns 0 for success, 1 otherwise.
 239  */
 240 void llc_build_and_send_test_pkt(struct llc_sap *sap,
 241                                  struct sk_buff *skb, u8 *dmac, u8 dsap)
 242 {
 243         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
 244
 245         ev->saddr.lsap = sap->laddr.lsap;
 246         ev->daddr.lsap = dsap;
 247         memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
 248         memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
 249
 250         ev->type      = LLC_SAP_EV_TYPE_PRIM;
 251         ev->prim      = LLC_TEST_PRIM;
 252         ev->prim_type = LLC_PRIM_TYPE_REQ;
 253         llc_sap_state_process(sap, skb);
 254 }
 255
 256 /**
 257  *      llc_build_and_send_xid_pkt - XID interface for upper layers
 258  *      @sap: sap to use
 259  *      @skb: packet to send
 260  *      @dmac: destination mac address
 261  *      @dsap: destination sap
 262  *
 263  *      This function is called when upper layer wants to send a XID pdu.
 264  *      Returns 0 for success, 1 otherwise.
 265  */
 266 void llc_build_and_send_xid_pkt(struct llc_sap *sap, struct sk_buff *skb,
 267                                 u8 *dmac, u8 dsap)
 268 {
 269         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
 270
 271         ev->saddr.lsap = sap->laddr.lsap;
 272         ev->daddr.lsap = dsap;
 273         memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
 274         memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
 275
 276         ev->type      = LLC_SAP_EV_TYPE_PRIM;
 277         ev->prim      = LLC_XID_PRIM;
 278         ev->prim_type = LLC_PRIM_TYPE_REQ;
 279         llc_sap_state_process(sap, skb);
 280 }
 281
 282 /**
 283  *      llc_sap_rcv - sends received pdus to the sap state machine
 284  *      @sap: current sap component structure.
 285  *      @skb: received frame.
 286  *
 287  *      Sends received pdus to the sap state machine.
 288  */
 289 static void llc_sap_rcv(struct llc_sap *sap, struct sk_buff *skb,
 290                         struct sock *sk)
 291 {
 292         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
 293
 294         ev->type   = LLC_SAP_EV_TYPE_PDU;
 295         ev->reason = 0;
 296         skb->sk = sk;
 297         llc_sap_state_process(sap, skb);
 298 }
 299
 300 /**
 301  *      llc_lookup_dgram - Finds dgram socket for the local sap/mac
 302  *      @sap: SAP
 303  *      @laddr: address of local LLC (MAC + SAP)
 304  *
 305  *      Search socket list of the SAP and finds connection using the local
 306  *      mac, and local sap. Returns pointer for socket found, %NULL otherwise.
 307  */
 308 static struct sock *llc_lookup_dgram(struct llc_sap *sap,
 309                                      const struct llc_addr *laddr)
 310 {
 311         struct sock *rc;
 312         struct hlist_node *node;
 313
 314         read_lock_bh(&sap->sk_list.lock);
 315         sk_for_each(rc, node, &sap->sk_list.list) {
 316                 struct llc_sock *llc = llc_sk(rc);
 317
 318                 if (rc->sk_type == SOCK_DGRAM &&
 319                     llc->laddr.lsap == laddr->lsap &&
 320                     llc_mac_match(llc->laddr.mac, laddr->mac)) {
 321                         sock_hold(rc);
 322                         goto found;
 323                 }
 324         }
 325         rc = NULL;
 326 found:
 327         read_unlock_bh(&sap->sk_list.lock);
 328         return rc;
 329 }
 330
 331 /**
 332  *      llc_sap_mcast - Deliver multicast PDU's to all matching datagram sockets.
 333  *      @sap: SAP
 334  *      @laddr: address of local LLC (MAC + SAP)
 335  *
 336  *      Search socket list of the SAP and finds connections with same sap.
 337  *      Deliver clone to each.
 338  */
 339 static void llc_sap_mcast(struct llc_sap *sap,
 340                           const struct llc_addr *laddr,
 341                           struct sk_buff *skb)
 342 {
 343         struct sock *sk;
 344         struct hlist_node *node;
 345
 346         read_lock_bh(&sap->sk_list.lock);
 347         sk_for_each(sk, node, &sap->sk_list.list) {
 348                 struct llc_sock *llc = llc_sk(sk);
 349                 struct sk_buff *skb1;
 350
 351                 if (sk->sk_type != SOCK_DGRAM)
 352                         continue;
 353
 354                 if (llc->laddr.lsap != laddr->lsap)
 355                         continue;
 356
 357                 if (llc->dev != skb->dev)
 358                         continue;
 359
 360                 skb1 = skb_clone(skb, GFP_ATOMIC);
 361                 if (!skb1)
 362                         break;
 363
 364                 sock_hold(sk);
 365                 llc_sap_rcv(sap, skb1, sk);
 366                 sock_put(sk);
 367         }
 368         read_unlock_bh(&sap->sk_list.lock);
 369 }
 370
 371
 372 void llc_sap_handler(struct llc_sap *sap, struct sk_buff *skb)
 373 {
 374         struct llc_addr laddr;
 375
 376         llc_pdu_decode_da(skb, laddr.mac);
 377         llc_pdu_decode_dsap(skb, &laddr.lsap);
 378
 379         if (llc_mac_multicast(laddr.mac)) {
 380                 llc_sap_mcast(sap, &laddr, skb);
 381                 kfree_skb(skb);
 382         } else {
 383                 struct sock *sk = llc_lookup_dgram(sap, &laddr);
 384                 if (sk) {
 385                         llc_sap_rcv(sap, skb, sk);
 386                         sock_put(sk);
 387                 } else
 388                         kfree_skb(skb);
 389         }
 390 }