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