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 <linux/tcp.h>
  25 #include <linux/llc.h>
  26
  27 /**
  28  *      llc_alloc_frame - allocates sk_buff for frame
  29  *
  30  *      Allocates an sk_buff for frame and initializes sk_buff fields.
  31  *      Returns allocated skb or %NULL when out of memory.
  32  */
  33 struct sk_buff *llc_alloc_frame(void)
  34 {
  35         struct sk_buff *skb = alloc_skb(128, GFP_ATOMIC);
  36
  37         if (skb) {
  38                 skb_reserve(skb, 50);
  39                 skb->nh.raw   = skb->h.raw = skb->data;
  40                 skb->protocol = htons(ETH_P_802_2);
  41                 skb->dev      = dev_base->next;
  42                 skb->mac.raw  = skb->head;
  43         }
  44         return skb;
  45 }
  46
  47 void llc_save_primitive(struct sk_buff* skb, u8 prim)
  48 {
  49         struct sockaddr_llc *addr = llc_ui_skb_cb(skb);
  50
  51        /* save primitive for use by the user. */
  52         addr->sllc_family = skb->sk->sk_family;
  53         addr->sllc_arphrd = skb->dev->type;
  54         addr->sllc_test   = prim == LLC_TEST_PRIM;
  55         addr->sllc_xid    = prim == LLC_XID_PRIM;
  56         addr->sllc_ua     = prim == LLC_DATAUNIT_PRIM;
  57         llc_pdu_decode_sa(skb, addr->sllc_mac);
  58         llc_pdu_decode_ssap(skb, &addr->sllc_sap);
  59 }
  60
  61 /**
  62  *      llc_sap_rtn_pdu - Informs upper layer on rx of an UI, XID or TEST pdu.
  63  *      @sap: pointer to SAP
  64  *      @skb: received pdu
  65  */
  66 void llc_sap_rtn_pdu(struct llc_sap *sap, struct sk_buff *skb)
  67 {
  68         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
  69         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
  70
  71         switch (LLC_U_PDU_RSP(pdu)) {
  72         case LLC_1_PDU_CMD_TEST:
  73                 ev->prim = LLC_TEST_PRIM;       break;
  74         case LLC_1_PDU_CMD_XID:
  75                 ev->prim = LLC_XID_PRIM;        break;
  76         case LLC_1_PDU_CMD_UI:
  77                 ev->prim = LLC_DATAUNIT_PRIM;   break;
  78         }
  79         ev->ind_cfm_flag = LLC_IND;
  80 }
  81
  82 /**
  83  *      llc_find_sap_trans - finds transition for event
  84  *      @sap: pointer to SAP
  85  *      @skb: happened event
  86  *
  87  *      This function finds transition that matches with happened event.
  88  *      Returns the pointer to found transition on success or %NULL for
  89  *      failure.
  90  */
  91 static struct llc_sap_state_trans *llc_find_sap_trans(struct llc_sap *sap,
  92                                                       struct sk_buff* skb)
  93 {
  94         int i = 0;
  95         struct llc_sap_state_trans *rc = NULL;
  96         struct llc_sap_state_trans **next_trans;
  97         struct llc_sap_state *curr_state = &llc_sap_state_table[sap->state - 1];
  98         /*
  99          * Search thru events for this state until list exhausted or until
 100          * its obvious the event is not valid for the current state
 101          */
 102         for (next_trans = curr_state->transitions; next_trans[i]->ev; i++)
 103                 if (!next_trans[i]->ev(sap, skb)) {
 104                         rc = next_trans[i]; /* got event match; return it */
 105                         break;
 106                 }
 107         return rc;
 108 }
 109
 110 /**
 111  *      llc_exec_sap_trans_actions - execute actions related to event
 112  *      @sap: pointer to SAP
 113  *      @trans: pointer to transition that it's actions must be performed
 114  *      @skb: happened event.
 115  *
 116  *      This function executes actions that is related to happened event.
 117  *      Returns 0 for success and 1 for failure of at least one action.
 118  */
 119 static int llc_exec_sap_trans_actions(struct llc_sap *sap,
 120                                       struct llc_sap_state_trans *trans,
 121                                       struct sk_buff *skb)
 122 {
 123         int rc = 0;
 124         llc_sap_action_t *next_action = trans->ev_actions;
 125
 126         for (; next_action && *next_action; next_action++)
 127                 if ((*next_action)(sap, skb))
 128                         rc = 1;
 129         return rc;
 130 }
 131
 132 /**
 133  *      llc_sap_next_state - finds transition, execs actions & change SAP state
 134  *      @sap: pointer to SAP
 135  *      @skb: happened event
 136  *
 137  *      This function finds transition that matches with happened event, then
 138  *      executes related actions and finally changes state of SAP. It returns
 139  *      0 on success and 1 for failure.
 140  */
 141 static int llc_sap_next_state(struct llc_sap *sap, struct sk_buff *skb)
 142 {
 143         int rc = 1;
 144         struct llc_sap_state_trans *trans;
 145
 146         if (sap->state > LLC_NR_SAP_STATES)
 147                 goto out;
 148         trans = llc_find_sap_trans(sap, skb);
 149         if (!trans)
 150                 goto out;
 151         /*
 152          * Got the state to which we next transition; perform the actions
 153          * associated with this transition before actually transitioning to the
 154          * next state
 155          */
 156         rc = llc_exec_sap_trans_actions(sap, trans, skb);
 157         if (rc)
 158                 goto out;
 159         /*
 160          * Transition SAP to next state if all actions execute successfully
 161          */
 162         sap->state = trans->next_state;
 163 out:
 164         return rc;
 165 }
 166
 167 /**
 168  *      llc_sap_state_process - sends event to SAP state machine
 169  *      @sap: sap to use
 170  *      @skb: pointer to occurred event
 171  *
 172  *      After executing actions of the event, upper layer will be indicated
 173  *      if needed(on receiving an UI frame). sk can be null for the
 174  *      datalink_proto case.
 175  */
 176 static void llc_sap_state_process(struct llc_sap *sap, struct sk_buff *skb)
 177 {
 178         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
 179
 180         /*
 181          * We have to hold the skb, because llc_sap_next_state
 182          * will kfree it in the sending path and we need to
 183          * look at the skb->cb, where we encode llc_sap_state_ev.
 184          */
 185         skb_get(skb);
 186         ev->ind_cfm_flag = 0;
 187         llc_sap_next_state(sap, skb);
 188         if (ev->ind_cfm_flag == LLC_IND) {
 189                 if (skb->sk->sk_state == TCP_LISTEN)
 190                         kfree_skb(skb);
 191                 else {
 192                         llc_save_primitive(skb, ev->prim);
 193
 194                         /* queue skb to the user. */
 195                         if (sock_queue_rcv_skb(skb->sk, skb))
 196                                 kfree_skb(skb);
 197                 }
 198         }
 199         kfree_skb(skb);
 200 }
 201
 202 /**
 203  *      llc_build_and_send_test_pkt - TEST interface for upper layers.
 204  *      @sap: sap to use
 205  *      @skb: packet to send
 206  *      @dmac: destination mac address
 207  *      @dsap: destination sap
 208  *
 209  *      This function is called when upper layer wants to send a TEST pdu.
 210  *      Returns 0 for success, 1 otherwise.
 211  */
 212 void llc_build_and_send_test_pkt(struct llc_sap *sap,
 213                                  struct sk_buff *skb, u8 *dmac, u8 dsap)
 214 {
 215         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
 216
 217         ev->saddr.lsap = sap->laddr.lsap;
 218         ev->daddr.lsap = dsap;
 219         memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
 220         memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
 221
 222         ev->type      = LLC_SAP_EV_TYPE_PRIM;
 223         ev->prim      = LLC_TEST_PRIM;
 224         ev->prim_type = LLC_PRIM_TYPE_REQ;
 225         llc_sap_state_process(sap, skb);
 226 }
 227
 228 /**
 229  *      llc_build_and_send_xid_pkt - XID interface for upper layers
 230  *      @sap: sap to use
 231  *      @skb: packet to send
 232  *      @dmac: destination mac address
 233  *      @dsap: destination sap
 234  *
 235  *      This function is called when upper layer wants to send a XID pdu.
 236  *      Returns 0 for success, 1 otherwise.
 237  */
 238 void llc_build_and_send_xid_pkt(struct llc_sap *sap, struct sk_buff *skb,
 239                                 u8 *dmac, u8 dsap)
 240 {
 241         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
 242
 243         ev->saddr.lsap = sap->laddr.lsap;
 244         ev->daddr.lsap = dsap;
 245         memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
 246         memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
 247
 248         ev->type      = LLC_SAP_EV_TYPE_PRIM;
 249         ev->prim      = LLC_XID_PRIM;
 250         ev->prim_type = LLC_PRIM_TYPE_REQ;
 251         llc_sap_state_process(sap, skb);
 252 }
 253
 254 /**
 255  *      llc_sap_rcv - sends received pdus to the sap state machine
 256  *      @sap: current sap component structure.
 257  *      @skb: received frame.
 258  *
 259  *      Sends received pdus to the sap state machine.
 260  */
 261 static void llc_sap_rcv(struct llc_sap *sap, struct sk_buff *skb)
 262 {
 263         struct llc_sap_state_ev *ev = llc_sap_ev(skb);
 264
 265         ev->type   = LLC_SAP_EV_TYPE_PDU;
 266         ev->reason = 0;
 267         llc_sap_state_process(sap, skb);
 268 }
 269
 270 /**
 271  *      llc_lookup_dgram - Finds dgram socket for the local sap/mac
 272  *      @sap: SAP
 273  *      @laddr: address of local LLC (MAC + SAP)
 274  *
 275  *      Search socket list of the SAP and finds connection using the local
 276  *      mac, and local sap. Returns pointer for socket found, %NULL otherwise.
 277  */
 278 static struct sock *llc_lookup_dgram(struct llc_sap *sap,
 279                                      struct llc_addr *laddr)
 280 {
 281         struct sock *rc;
 282         struct hlist_node *node;
 283
 284         read_lock_bh(&sap->sk_list.lock);
 285         sk_for_each(rc, node, &sap->sk_list.list) {
 286                 struct llc_sock *llc = llc_sk(rc);
 287
 288                 if (rc->sk_type == SOCK_DGRAM &&
 289                     llc->laddr.lsap == laddr->lsap &&
 290                     llc_mac_match(llc->laddr.mac, laddr->mac)) {
 291                         sock_hold(rc);
 292                         goto found;
 293                 }
 294         }
 295         rc = NULL;
 296 found:
 297         read_unlock_bh(&sap->sk_list.lock);
 298         return rc;
 299 }
 300
 301 void llc_sap_handler(struct llc_sap *sap, struct sk_buff *skb)
 302 {
 303         struct llc_addr laddr;
 304         struct sock *sk;
 305
 306         llc_pdu_decode_da(skb, laddr.mac);
 307         llc_pdu_decode_dsap(skb, &laddr.lsap);
 308
 309         sk = llc_lookup_dgram(sap, &laddr);
 310         if (sk) {
 311                 skb->sk = sk;
 312                 llc_sap_rcv(sap, skb);
 313                 sock_put(sk);
 314         } else
 315                 kfree_skb(skb);
 316 }