linux/net/llc/llc_conn.c
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   1/*
   2 * llc_conn.c - Driver routines for connection 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 <linux/init.h>
  16#include <linux/slab.h>
  17#include <net/llc_sap.h>
  18#include <net/llc_conn.h>
  19#include <net/sock.h>
  20#include <net/tcp_states.h>
  21#include <net/llc_c_ev.h>
  22#include <net/llc_c_ac.h>
  23#include <net/llc_c_st.h>
  24#include <net/llc_pdu.h>
  25
  26#if 0
  27#define dprintk(args...) printk(KERN_DEBUG args)
  28#else
  29#define dprintk(args...)
  30#endif
  31
  32static int llc_find_offset(int state, int ev_type);
  33static void llc_conn_send_pdus(struct sock *sk);
  34static int llc_conn_service(struct sock *sk, struct sk_buff *skb);
  35static int llc_exec_conn_trans_actions(struct sock *sk,
  36                                       struct llc_conn_state_trans *trans,
  37                                       struct sk_buff *ev);
  38static struct llc_conn_state_trans *llc_qualify_conn_ev(struct sock *sk,
  39                                                        struct sk_buff *skb);
  40
  41/* Offset table on connection states transition diagram */
  42static int llc_offset_table[NBR_CONN_STATES][NBR_CONN_EV];
  43
  44int sysctl_llc2_ack_timeout = LLC2_ACK_TIME * HZ;
  45int sysctl_llc2_p_timeout = LLC2_P_TIME * HZ;
  46int sysctl_llc2_rej_timeout = LLC2_REJ_TIME * HZ;
  47int sysctl_llc2_busy_timeout = LLC2_BUSY_TIME * HZ;
  48
  49/**
  50 *      llc_conn_state_process - sends event to connection state machine
  51 *      @sk: connection
  52 *      @skb: occurred event
  53 *
  54 *      Sends an event to connection state machine. After processing event
  55 *      (executing it's actions and changing state), upper layer will be
  56 *      indicated or confirmed, if needed. Returns 0 for success, 1 for
  57 *      failure. The socket lock has to be held before calling this function.
  58 *
  59 *      This function always consumes a reference to the skb.
  60 */
  61int llc_conn_state_process(struct sock *sk, struct sk_buff *skb)
  62{
  63        int rc;
  64        struct llc_sock *llc = llc_sk(skb->sk);
  65        struct llc_conn_state_ev *ev = llc_conn_ev(skb);
  66
  67        ev->ind_prim = ev->cfm_prim = 0;
  68        /*
  69         * Send event to state machine
  70         */
  71        rc = llc_conn_service(skb->sk, skb);
  72        if (unlikely(rc != 0)) {
  73                printk(KERN_ERR "%s: llc_conn_service failed\n", __func__);
  74                goto out_skb_put;
  75        }
  76
  77        switch (ev->ind_prim) {
  78        case LLC_DATA_PRIM:
  79                skb_get(skb);
  80                llc_save_primitive(sk, skb, LLC_DATA_PRIM);
  81                if (unlikely(sock_queue_rcv_skb(sk, skb))) {
  82                        /*
  83                         * shouldn't happen
  84                         */
  85                        printk(KERN_ERR "%s: sock_queue_rcv_skb failed!\n",
  86                               __func__);
  87                        kfree_skb(skb);
  88                }
  89                break;
  90        case LLC_CONN_PRIM:
  91                /*
  92                 * Can't be sock_queue_rcv_skb, because we have to leave the
  93                 * skb->sk pointing to the newly created struct sock in
  94                 * llc_conn_handler. -acme
  95                 */
  96                skb_get(skb);
  97                skb_queue_tail(&sk->sk_receive_queue, skb);
  98                sk->sk_state_change(sk);
  99                break;
 100        case LLC_DISC_PRIM:
 101                sock_hold(sk);
 102                if (sk->sk_type == SOCK_STREAM &&
 103                    sk->sk_state == TCP_ESTABLISHED) {
 104                        sk->sk_shutdown       = SHUTDOWN_MASK;
 105                        sk->sk_socket->state  = SS_UNCONNECTED;
 106                        sk->sk_state          = TCP_CLOSE;
 107                        if (!sock_flag(sk, SOCK_DEAD)) {
 108                                sock_set_flag(sk, SOCK_DEAD);
 109                                sk->sk_state_change(sk);
 110                        }
 111                }
 112                sock_put(sk);
 113                break;
 114        case LLC_RESET_PRIM:
 115                /*
 116                 * FIXME:
 117                 * RESET is not being notified to upper layers for now
 118                 */
 119                printk(KERN_INFO "%s: received a reset ind!\n", __func__);
 120                break;
 121        default:
 122                if (ev->ind_prim)
 123                        printk(KERN_INFO "%s: received unknown %d prim!\n",
 124                                __func__, ev->ind_prim);
 125                /* No indication */
 126                break;
 127        }
 128
 129        switch (ev->cfm_prim) {
 130        case LLC_DATA_PRIM:
 131                if (!llc_data_accept_state(llc->state))
 132                        sk->sk_write_space(sk);
 133                else
 134                        rc = llc->failed_data_req = 1;
 135                break;
 136        case LLC_CONN_PRIM:
 137                if (sk->sk_type == SOCK_STREAM &&
 138                    sk->sk_state == TCP_SYN_SENT) {
 139                        if (ev->status) {
 140                                sk->sk_socket->state = SS_UNCONNECTED;
 141                                sk->sk_state         = TCP_CLOSE;
 142                        } else {
 143                                sk->sk_socket->state = SS_CONNECTED;
 144                                sk->sk_state         = TCP_ESTABLISHED;
 145                        }
 146                        sk->sk_state_change(sk);
 147                }
 148                break;
 149        case LLC_DISC_PRIM:
 150                sock_hold(sk);
 151                if (sk->sk_type == SOCK_STREAM && sk->sk_state == TCP_CLOSING) {
 152                        sk->sk_socket->state = SS_UNCONNECTED;
 153                        sk->sk_state         = TCP_CLOSE;
 154                        sk->sk_state_change(sk);
 155                }
 156                sock_put(sk);
 157                break;
 158        case LLC_RESET_PRIM:
 159                /*
 160                 * FIXME:
 161                 * RESET is not being notified to upper layers for now
 162                 */
 163                printk(KERN_INFO "%s: received a reset conf!\n", __func__);
 164                break;
 165        default:
 166                if (ev->cfm_prim)
 167                        printk(KERN_INFO "%s: received unknown %d prim!\n",
 168                                        __func__, ev->cfm_prim);
 169                /* No confirmation */
 170                break;
 171        }
 172out_skb_put:
 173        kfree_skb(skb);
 174        return rc;
 175}
 176
 177void llc_conn_send_pdu(struct sock *sk, struct sk_buff *skb)
 178{
 179        /* queue PDU to send to MAC layer */
 180        skb_queue_tail(&sk->sk_write_queue, skb);
 181        llc_conn_send_pdus(sk);
 182}
 183
 184/**
 185 *      llc_conn_rtn_pdu - sends received data pdu to upper layer
 186 *      @sk: Active connection
 187 *      @skb: Received data frame
 188 *
 189 *      Sends received data pdu to upper layer (by using indicate function).
 190 *      Prepares service parameters (prim and prim_data). calling indication
 191 *      function will be done in llc_conn_state_process.
 192 */
 193void llc_conn_rtn_pdu(struct sock *sk, struct sk_buff *skb)
 194{
 195        struct llc_conn_state_ev *ev = llc_conn_ev(skb);
 196
 197        ev->ind_prim = LLC_DATA_PRIM;
 198}
 199
 200/**
 201 *      llc_conn_resend_i_pdu_as_cmd - resend all all unacknowledged I PDUs
 202 *      @sk: active connection
 203 *      @nr: NR
 204 *      @first_p_bit: p_bit value of first pdu
 205 *
 206 *      Resend all unacknowledged I PDUs, starting with the NR; send first as
 207 *      command PDU with P bit equal first_p_bit; if more than one send
 208 *      subsequent as command PDUs with P bit equal zero (0).
 209 */
 210void llc_conn_resend_i_pdu_as_cmd(struct sock *sk, u8 nr, u8 first_p_bit)
 211{
 212        struct sk_buff *skb;
 213        struct llc_pdu_sn *pdu;
 214        u16 nbr_unack_pdus;
 215        struct llc_sock *llc;
 216        u8 howmany_resend = 0;
 217
 218        llc_conn_remove_acked_pdus(sk, nr, &nbr_unack_pdus);
 219        if (!nbr_unack_pdus)
 220                goto out;
 221        /*
 222         * Process unack PDUs only if unack queue is not empty; remove
 223         * appropriate PDUs, fix them up, and put them on mac_pdu_q.
 224         */
 225        llc = llc_sk(sk);
 226
 227        while ((skb = skb_dequeue(&llc->pdu_unack_q)) != NULL) {
 228                pdu = llc_pdu_sn_hdr(skb);
 229                llc_pdu_set_cmd_rsp(skb, LLC_PDU_CMD);
 230                llc_pdu_set_pf_bit(skb, first_p_bit);
 231                skb_queue_tail(&sk->sk_write_queue, skb);
 232                first_p_bit = 0;
 233                llc->vS = LLC_I_GET_NS(pdu);
 234                howmany_resend++;
 235        }
 236        if (howmany_resend > 0)
 237                llc->vS = (llc->vS + 1) % LLC_2_SEQ_NBR_MODULO;
 238        /* any PDUs to re-send are queued up; start sending to MAC */
 239        llc_conn_send_pdus(sk);
 240out:;
 241}
 242
 243/**
 244 *      llc_conn_resend_i_pdu_as_rsp - Resend all unacknowledged I PDUs
 245 *      @sk: active connection.
 246 *      @nr: NR
 247 *      @first_f_bit: f_bit value of first pdu.
 248 *
 249 *      Resend all unacknowledged I PDUs, starting with the NR; send first as
 250 *      response PDU with F bit equal first_f_bit; if more than one send
 251 *      subsequent as response PDUs with F bit equal zero (0).
 252 */
 253void llc_conn_resend_i_pdu_as_rsp(struct sock *sk, u8 nr, u8 first_f_bit)
 254{
 255        struct sk_buff *skb;
 256        u16 nbr_unack_pdus;
 257        struct llc_sock *llc = llc_sk(sk);
 258        u8 howmany_resend = 0;
 259
 260        llc_conn_remove_acked_pdus(sk, nr, &nbr_unack_pdus);
 261        if (!nbr_unack_pdus)
 262                goto out;
 263        /*
 264         * Process unack PDUs only if unack queue is not empty; remove
 265         * appropriate PDUs, fix them up, and put them on mac_pdu_q
 266         */
 267        while ((skb = skb_dequeue(&llc->pdu_unack_q)) != NULL) {
 268                struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
 269
 270                llc_pdu_set_cmd_rsp(skb, LLC_PDU_RSP);
 271                llc_pdu_set_pf_bit(skb, first_f_bit);
 272                skb_queue_tail(&sk->sk_write_queue, skb);
 273                first_f_bit = 0;
 274                llc->vS = LLC_I_GET_NS(pdu);
 275                howmany_resend++;
 276        }
 277        if (howmany_resend > 0)
 278                llc->vS = (llc->vS + 1) % LLC_2_SEQ_NBR_MODULO;
 279        /* any PDUs to re-send are queued up; start sending to MAC */
 280        llc_conn_send_pdus(sk);
 281out:;
 282}
 283
 284/**
 285 *      llc_conn_remove_acked_pdus - Removes acknowledged pdus from tx queue
 286 *      @sk: active connection
 287 *      @nr: NR
 288 *      @how_many_unacked: size of pdu_unack_q after removing acked pdus
 289 *
 290 *      Removes acknowledged pdus from transmit queue (pdu_unack_q). Returns
 291 *      the number of pdus that removed from queue.
 292 */
 293int llc_conn_remove_acked_pdus(struct sock *sk, u8 nr, u16 *how_many_unacked)
 294{
 295        int pdu_pos, i;
 296        struct sk_buff *skb;
 297        struct llc_pdu_sn *pdu;
 298        int nbr_acked = 0;
 299        struct llc_sock *llc = llc_sk(sk);
 300        int q_len = skb_queue_len(&llc->pdu_unack_q);
 301
 302        if (!q_len)
 303                goto out;
 304        skb = skb_peek(&llc->pdu_unack_q);
 305        pdu = llc_pdu_sn_hdr(skb);
 306
 307        /* finding position of last acked pdu in queue */
 308        pdu_pos = ((int)LLC_2_SEQ_NBR_MODULO + (int)nr -
 309                        (int)LLC_I_GET_NS(pdu)) % LLC_2_SEQ_NBR_MODULO;
 310
 311        for (i = 0; i < pdu_pos && i < q_len; i++) {
 312                skb = skb_dequeue(&llc->pdu_unack_q);
 313                kfree_skb(skb);
 314                nbr_acked++;
 315        }
 316out:
 317        *how_many_unacked = skb_queue_len(&llc->pdu_unack_q);
 318        return nbr_acked;
 319}
 320
 321/**
 322 *      llc_conn_send_pdus - Sends queued PDUs
 323 *      @sk: active connection
 324 *
 325 *      Sends queued pdus to MAC layer for transmission.
 326 */
 327static void llc_conn_send_pdus(struct sock *sk)
 328{
 329        struct sk_buff *skb;
 330
 331        while ((skb = skb_dequeue(&sk->sk_write_queue)) != NULL) {
 332                struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
 333
 334                if (LLC_PDU_TYPE_IS_I(pdu) &&
 335                    !(skb->dev->flags & IFF_LOOPBACK)) {
 336                        struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
 337
 338                        skb_queue_tail(&llc_sk(sk)->pdu_unack_q, skb);
 339                        if (!skb2)
 340                                break;
 341                        skb = skb2;
 342                }
 343                dev_queue_xmit(skb);
 344        }
 345}
 346
 347/**
 348 *      llc_conn_service - finds transition and changes state of connection
 349 *      @sk: connection
 350 *      @skb: happened event
 351 *
 352 *      This function finds transition that matches with happened event, then
 353 *      executes related actions and finally changes state of connection.
 354 *      Returns 0 for success, 1 for failure.
 355 */
 356static int llc_conn_service(struct sock *sk, struct sk_buff *skb)
 357{
 358        int rc = 1;
 359        struct llc_sock *llc = llc_sk(sk);
 360        struct llc_conn_state_trans *trans;
 361
 362        if (llc->state > NBR_CONN_STATES)
 363                goto out;
 364        rc = 0;
 365        trans = llc_qualify_conn_ev(sk, skb);
 366        if (trans) {
 367                rc = llc_exec_conn_trans_actions(sk, trans, skb);
 368                if (!rc && trans->next_state != NO_STATE_CHANGE) {
 369                        llc->state = trans->next_state;
 370                        if (!llc_data_accept_state(llc->state))
 371                                sk->sk_state_change(sk);
 372                }
 373        }
 374out:
 375        return rc;
 376}
 377
 378/**
 379 *      llc_qualify_conn_ev - finds transition for event
 380 *      @sk: connection
 381 *      @skb: happened event
 382 *
 383 *      This function finds transition that matches with happened event.
 384 *      Returns pointer to found transition on success, %NULL otherwise.
 385 */
 386static struct llc_conn_state_trans *llc_qualify_conn_ev(struct sock *sk,
 387                                                        struct sk_buff *skb)
 388{
 389        struct llc_conn_state_trans **next_trans;
 390        const llc_conn_ev_qfyr_t *next_qualifier;
 391        struct llc_conn_state_ev *ev = llc_conn_ev(skb);
 392        struct llc_sock *llc = llc_sk(sk);
 393        struct llc_conn_state *curr_state =
 394                                        &llc_conn_state_table[llc->state - 1];
 395
 396        /* search thru events for this state until
 397         * list exhausted or until no more
 398         */
 399        for (next_trans = curr_state->transitions +
 400                llc_find_offset(llc->state - 1, ev->type);
 401             (*next_trans)->ev; next_trans++) {
 402                if (!((*next_trans)->ev)(sk, skb)) {
 403                        /* got POSSIBLE event match; the event may require
 404                         * qualification based on the values of a number of
 405                         * state flags; if all qualifications are met (i.e.,
 406                         * if all qualifying functions return success, or 0,
 407                         * then this is THE event we're looking for
 408                         */
 409                        for (next_qualifier = (*next_trans)->ev_qualifiers;
 410                             next_qualifier && *next_qualifier &&
 411                             !(*next_qualifier)(sk, skb); next_qualifier++)
 412                                /* nothing */;
 413                        if (!next_qualifier || !*next_qualifier)
 414                                /* all qualifiers executed successfully; this is
 415                                 * our transition; return it so we can perform
 416                                 * the associated actions & change the state
 417                                 */
 418                                return *next_trans;
 419                }
 420        }
 421        return NULL;
 422}
 423
 424/**
 425 *      llc_exec_conn_trans_actions - executes related actions
 426 *      @sk: connection
 427 *      @trans: transition that it's actions must be performed
 428 *      @skb: event
 429 *
 430 *      Executes actions that is related to happened event. Returns 0 for
 431 *      success, 1 to indicate failure of at least one action.
 432 */
 433static int llc_exec_conn_trans_actions(struct sock *sk,
 434                                       struct llc_conn_state_trans *trans,
 435                                       struct sk_buff *skb)
 436{
 437        int rc = 0;
 438        const llc_conn_action_t *next_action;
 439
 440        for (next_action = trans->ev_actions;
 441             next_action && *next_action; next_action++) {
 442                int rc2 = (*next_action)(sk, skb);
 443
 444                if (rc2 == 2) {
 445                        rc = rc2;
 446                        break;
 447                } else if (rc2)
 448                        rc = 1;
 449        }
 450        return rc;
 451}
 452
 453static inline bool llc_estab_match(const struct llc_sap *sap,
 454                                   const struct llc_addr *daddr,
 455                                   const struct llc_addr *laddr,
 456                                   const struct sock *sk)
 457{
 458        struct llc_sock *llc = llc_sk(sk);
 459
 460        return llc->laddr.lsap == laddr->lsap &&
 461                llc->daddr.lsap == daddr->lsap &&
 462                ether_addr_equal(llc->laddr.mac, laddr->mac) &&
 463                ether_addr_equal(llc->daddr.mac, daddr->mac);
 464}
 465
 466/**
 467 *      __llc_lookup_established - Finds connection for the remote/local sap/mac
 468 *      @sap: SAP
 469 *      @daddr: address of remote LLC (MAC + SAP)
 470 *      @laddr: address of local LLC (MAC + SAP)
 471 *
 472 *      Search connection list of the SAP and finds connection using the remote
 473 *      mac, remote sap, local mac, and local sap. Returns pointer for
 474 *      connection found, %NULL otherwise.
 475 *      Caller has to make sure local_bh is disabled.
 476 */
 477static struct sock *__llc_lookup_established(struct llc_sap *sap,
 478                                             struct llc_addr *daddr,
 479                                             struct llc_addr *laddr)
 480{
 481        struct sock *rc;
 482        struct hlist_nulls_node *node;
 483        int slot = llc_sk_laddr_hashfn(sap, laddr);
 484        struct hlist_nulls_head *laddr_hb = &sap->sk_laddr_hash[slot];
 485
 486        rcu_read_lock();
 487again:
 488        sk_nulls_for_each_rcu(rc, node, laddr_hb) {
 489                if (llc_estab_match(sap, daddr, laddr, rc)) {
 490                        /* Extra checks required by SLAB_TYPESAFE_BY_RCU */
 491                        if (unlikely(!refcount_inc_not_zero(&rc->sk_refcnt)))
 492                                goto again;
 493                        if (unlikely(llc_sk(rc)->sap != sap ||
 494                                     !llc_estab_match(sap, daddr, laddr, rc))) {
 495                                sock_put(rc);
 496                                continue;
 497                        }
 498                        goto found;
 499                }
 500        }
 501        rc = NULL;
 502        /*
 503         * if the nulls value we got at the end of this lookup is
 504         * not the expected one, we must restart lookup.
 505         * We probably met an item that was moved to another chain.
 506         */
 507        if (unlikely(get_nulls_value(node) != slot))
 508                goto again;
 509found:
 510        rcu_read_unlock();
 511        return rc;
 512}
 513
 514struct sock *llc_lookup_established(struct llc_sap *sap,
 515                                    struct llc_addr *daddr,
 516                                    struct llc_addr *laddr)
 517{
 518        struct sock *sk;
 519
 520        local_bh_disable();
 521        sk = __llc_lookup_established(sap, daddr, laddr);
 522        local_bh_enable();
 523        return sk;
 524}
 525
 526static inline bool llc_listener_match(const struct llc_sap *sap,
 527                                      const struct llc_addr *laddr,
 528                                      const struct sock *sk)
 529{
 530        struct llc_sock *llc = llc_sk(sk);
 531
 532        return sk->sk_type == SOCK_STREAM && sk->sk_state == TCP_LISTEN &&
 533                llc->laddr.lsap == laddr->lsap &&
 534                ether_addr_equal(llc->laddr.mac, laddr->mac);
 535}
 536
 537static struct sock *__llc_lookup_listener(struct llc_sap *sap,
 538                                          struct llc_addr *laddr)
 539{
 540        struct sock *rc;
 541        struct hlist_nulls_node *node;
 542        int slot = llc_sk_laddr_hashfn(sap, laddr);
 543        struct hlist_nulls_head *laddr_hb = &sap->sk_laddr_hash[slot];
 544
 545        rcu_read_lock();
 546again:
 547        sk_nulls_for_each_rcu(rc, node, laddr_hb) {
 548                if (llc_listener_match(sap, laddr, rc)) {
 549                        /* Extra checks required by SLAB_TYPESAFE_BY_RCU */
 550                        if (unlikely(!refcount_inc_not_zero(&rc->sk_refcnt)))
 551                                goto again;
 552                        if (unlikely(llc_sk(rc)->sap != sap ||
 553                                     !llc_listener_match(sap, laddr, rc))) {
 554                                sock_put(rc);
 555                                continue;
 556                        }
 557                        goto found;
 558                }
 559        }
 560        rc = NULL;
 561        /*
 562         * if the nulls value we got at the end of this lookup is
 563         * not the expected one, we must restart lookup.
 564         * We probably met an item that was moved to another chain.
 565         */
 566        if (unlikely(get_nulls_value(node) != slot))
 567                goto again;
 568found:
 569        rcu_read_unlock();
 570        return rc;
 571}
 572
 573/**
 574 *      llc_lookup_listener - Finds listener for local MAC + SAP
 575 *      @sap: SAP
 576 *      @laddr: address of local LLC (MAC + SAP)
 577 *
 578 *      Search connection list of the SAP and finds connection listening on
 579 *      local mac, and local sap. Returns pointer for parent socket found,
 580 *      %NULL otherwise.
 581 *      Caller has to make sure local_bh is disabled.
 582 */
 583static struct sock *llc_lookup_listener(struct llc_sap *sap,
 584                                        struct llc_addr *laddr)
 585{
 586        static struct llc_addr null_addr;
 587        struct sock *rc = __llc_lookup_listener(sap, laddr);
 588
 589        if (!rc)
 590                rc = __llc_lookup_listener(sap, &null_addr);
 591
 592        return rc;
 593}
 594
 595static struct sock *__llc_lookup(struct llc_sap *sap,
 596                                 struct llc_addr *daddr,
 597                                 struct llc_addr *laddr)
 598{
 599        struct sock *sk = __llc_lookup_established(sap, daddr, laddr);
 600
 601        return sk ? : llc_lookup_listener(sap, laddr);
 602}
 603
 604/**
 605 *      llc_data_accept_state - designates if in this state data can be sent.
 606 *      @state: state of connection.
 607 *
 608 *      Returns 0 if data can be sent, 1 otherwise.
 609 */
 610u8 llc_data_accept_state(u8 state)
 611{
 612        return state != LLC_CONN_STATE_NORMAL && state != LLC_CONN_STATE_BUSY &&
 613               state != LLC_CONN_STATE_REJ;
 614}
 615
 616/**
 617 *      llc_find_next_offset - finds offset for next category of transitions
 618 *      @state: state table.
 619 *      @offset: start offset.
 620 *
 621 *      Finds offset of next category of transitions in transition table.
 622 *      Returns the start index of next category.
 623 */
 624static u16 __init llc_find_next_offset(struct llc_conn_state *state, u16 offset)
 625{
 626        u16 cnt = 0;
 627        struct llc_conn_state_trans **next_trans;
 628
 629        for (next_trans = state->transitions + offset;
 630             (*next_trans)->ev; next_trans++)
 631                ++cnt;
 632        return cnt;
 633}
 634
 635/**
 636 *      llc_build_offset_table - builds offset table of connection
 637 *
 638 *      Fills offset table of connection state transition table
 639 *      (llc_offset_table).
 640 */
 641void __init llc_build_offset_table(void)
 642{
 643        struct llc_conn_state *curr_state;
 644        int state, ev_type, next_offset;
 645
 646        for (state = 0; state < NBR_CONN_STATES; state++) {
 647                curr_state = &llc_conn_state_table[state];
 648                next_offset = 0;
 649                for (ev_type = 0; ev_type < NBR_CONN_EV; ev_type++) {
 650                        llc_offset_table[state][ev_type] = next_offset;
 651                        next_offset += llc_find_next_offset(curr_state,
 652                                                            next_offset) + 1;
 653                }
 654        }
 655}
 656
 657/**
 658 *      llc_find_offset - finds start offset of category of transitions
 659 *      @state: state of connection
 660 *      @ev_type: type of happened event
 661 *
 662 *      Finds start offset of desired category of transitions. Returns the
 663 *      desired start offset.
 664 */
 665static int llc_find_offset(int state, int ev_type)
 666{
 667        int rc = 0;
 668        /* at this stage, llc_offset_table[..][2] is not important. it is for
 669         * init_pf_cycle and I don't know what is it.
 670         */
 671        switch (ev_type) {
 672        case LLC_CONN_EV_TYPE_PRIM:
 673                rc = llc_offset_table[state][0]; break;
 674        case LLC_CONN_EV_TYPE_PDU:
 675                rc = llc_offset_table[state][4]; break;
 676        case LLC_CONN_EV_TYPE_SIMPLE:
 677                rc = llc_offset_table[state][1]; break;
 678        case LLC_CONN_EV_TYPE_P_TMR:
 679        case LLC_CONN_EV_TYPE_ACK_TMR:
 680        case LLC_CONN_EV_TYPE_REJ_TMR:
 681        case LLC_CONN_EV_TYPE_BUSY_TMR:
 682                rc = llc_offset_table[state][3]; break;
 683        }
 684        return rc;
 685}
 686
 687/**
 688 *      llc_sap_add_socket - adds a socket to a SAP
 689 *      @sap: SAP
 690 *      @sk: socket
 691 *
 692 *      This function adds a socket to the hash tables of a SAP.
 693 */
 694void llc_sap_add_socket(struct llc_sap *sap, struct sock *sk)
 695{
 696        struct llc_sock *llc = llc_sk(sk);
 697        struct hlist_head *dev_hb = llc_sk_dev_hash(sap, llc->dev->ifindex);
 698        struct hlist_nulls_head *laddr_hb = llc_sk_laddr_hash(sap, &llc->laddr);
 699
 700        llc_sap_hold(sap);
 701        llc_sk(sk)->sap = sap;
 702
 703        spin_lock_bh(&sap->sk_lock);
 704        sock_set_flag(sk, SOCK_RCU_FREE);
 705        sap->sk_count++;
 706        sk_nulls_add_node_rcu(sk, laddr_hb);
 707        hlist_add_head(&llc->dev_hash_node, dev_hb);
 708        spin_unlock_bh(&sap->sk_lock);
 709}
 710
 711/**
 712 *      llc_sap_remove_socket - removes a socket from SAP
 713 *      @sap: SAP
 714 *      @sk: socket
 715 *
 716 *      This function removes a connection from the hash tables of a SAP if
 717 *      the connection was in this list.
 718 */
 719void llc_sap_remove_socket(struct llc_sap *sap, struct sock *sk)
 720{
 721        struct llc_sock *llc = llc_sk(sk);
 722
 723        spin_lock_bh(&sap->sk_lock);
 724        sk_nulls_del_node_init_rcu(sk);
 725        hlist_del(&llc->dev_hash_node);
 726        sap->sk_count--;
 727        spin_unlock_bh(&sap->sk_lock);
 728        llc_sap_put(sap);
 729}
 730
 731/**
 732 *      llc_conn_rcv - sends received pdus to the connection state machine
 733 *      @sk: current connection structure.
 734 *      @skb: received frame.
 735 *
 736 *      Sends received pdus to the connection state machine.
 737 */
 738static int llc_conn_rcv(struct sock *sk, struct sk_buff *skb)
 739{
 740        struct llc_conn_state_ev *ev = llc_conn_ev(skb);
 741
 742        ev->type   = LLC_CONN_EV_TYPE_PDU;
 743        ev->reason = 0;
 744        return llc_conn_state_process(sk, skb);
 745}
 746
 747static struct sock *llc_create_incoming_sock(struct sock *sk,
 748                                             struct net_device *dev,
 749                                             struct llc_addr *saddr,
 750                                             struct llc_addr *daddr)
 751{
 752        struct sock *newsk = llc_sk_alloc(sock_net(sk), sk->sk_family, GFP_ATOMIC,
 753                                          sk->sk_prot, 0);
 754        struct llc_sock *newllc, *llc = llc_sk(sk);
 755
 756        if (!newsk)
 757                goto out;
 758        newllc = llc_sk(newsk);
 759        memcpy(&newllc->laddr, daddr, sizeof(newllc->laddr));
 760        memcpy(&newllc->daddr, saddr, sizeof(newllc->daddr));
 761        newllc->dev = dev;
 762        dev_hold(dev);
 763        llc_sap_add_socket(llc->sap, newsk);
 764        llc_sap_hold(llc->sap);
 765out:
 766        return newsk;
 767}
 768
 769void llc_conn_handler(struct llc_sap *sap, struct sk_buff *skb)
 770{
 771        struct llc_addr saddr, daddr;
 772        struct sock *sk;
 773
 774        llc_pdu_decode_sa(skb, saddr.mac);
 775        llc_pdu_decode_ssap(skb, &saddr.lsap);
 776        llc_pdu_decode_da(skb, daddr.mac);
 777        llc_pdu_decode_dsap(skb, &daddr.lsap);
 778
 779        sk = __llc_lookup(sap, &saddr, &daddr);
 780        if (!sk)
 781                goto drop;
 782
 783        bh_lock_sock(sk);
 784        /*
 785         * This has to be done here and not at the upper layer ->accept
 786         * method because of the way the PROCOM state machine works:
 787         * it needs to set several state variables (see, for instance,
 788         * llc_adm_actions_2 in net/llc/llc_c_st.c) and send a packet to
 789         * the originator of the new connection, and this state has to be
 790         * in the newly created struct sock private area. -acme
 791         */
 792        if (unlikely(sk->sk_state == TCP_LISTEN)) {
 793                struct sock *newsk = llc_create_incoming_sock(sk, skb->dev,
 794                                                              &saddr, &daddr);
 795                if (!newsk)
 796                        goto drop_unlock;
 797                skb_set_owner_r(skb, newsk);
 798        } else {
 799                /*
 800                 * Can't be skb_set_owner_r, this will be done at the
 801                 * llc_conn_state_process function, later on, when we will use
 802                 * skb_queue_rcv_skb to send it to upper layers, this is
 803                 * another trick required to cope with how the PROCOM state
 804                 * machine works. -acme
 805                 */
 806                skb_orphan(skb);
 807                sock_hold(sk);
 808                skb->sk = sk;
 809                skb->destructor = sock_efree;
 810        }
 811        if (!sock_owned_by_user(sk))
 812                llc_conn_rcv(sk, skb);
 813        else {
 814                dprintk("%s: adding to backlog...\n", __func__);
 815                llc_set_backlog_type(skb, LLC_PACKET);
 816                if (sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf)))
 817                        goto drop_unlock;
 818        }
 819out:
 820        bh_unlock_sock(sk);
 821        sock_put(sk);
 822        return;
 823drop:
 824        kfree_skb(skb);
 825        return;
 826drop_unlock:
 827        kfree_skb(skb);
 828        goto out;
 829}
 830
 831#undef LLC_REFCNT_DEBUG
 832#ifdef LLC_REFCNT_DEBUG
 833static atomic_t llc_sock_nr;
 834#endif
 835
 836/**
 837 *      llc_backlog_rcv - Processes rx frames and expired timers.
 838 *      @sk: LLC sock (p8022 connection)
 839 *      @skb: queued rx frame or event
 840 *
 841 *      This function processes frames that has received and timers that has
 842 *      expired during sending an I pdu (refer to data_req_handler).  frames
 843 *      queue by llc_rcv function (llc_mac.c) and timers queue by timer
 844 *      callback functions(llc_c_ac.c).
 845 */
 846static int llc_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 847{
 848        int rc = 0;
 849        struct llc_sock *llc = llc_sk(sk);
 850
 851        if (likely(llc_backlog_type(skb) == LLC_PACKET)) {
 852                if (likely(llc->state > 1)) /* not closed */
 853                        rc = llc_conn_rcv(sk, skb);
 854                else
 855                        goto out_kfree_skb;
 856        } else if (llc_backlog_type(skb) == LLC_EVENT) {
 857                /* timer expiration event */
 858                if (likely(llc->state > 1))  /* not closed */
 859                        rc = llc_conn_state_process(sk, skb);
 860                else
 861                        goto out_kfree_skb;
 862        } else {
 863                printk(KERN_ERR "%s: invalid skb in backlog\n", __func__);
 864                goto out_kfree_skb;
 865        }
 866out:
 867        return rc;
 868out_kfree_skb:
 869        kfree_skb(skb);
 870        goto out;
 871}
 872
 873/**
 874 *     llc_sk_init - Initializes a socket with default llc values.
 875 *     @sk: socket to initialize.
 876 *
 877 *     Initializes a socket with default llc values.
 878 */
 879static void llc_sk_init(struct sock *sk)
 880{
 881        struct llc_sock *llc = llc_sk(sk);
 882
 883        llc->state    = LLC_CONN_STATE_ADM;
 884        llc->inc_cntr = llc->dec_cntr = 2;
 885        llc->dec_step = llc->connect_step = 1;
 886
 887        timer_setup(&llc->ack_timer.timer, llc_conn_ack_tmr_cb, 0);
 888        llc->ack_timer.expire         = sysctl_llc2_ack_timeout;
 889
 890        timer_setup(&llc->pf_cycle_timer.timer, llc_conn_pf_cycle_tmr_cb, 0);
 891        llc->pf_cycle_timer.expire         = sysctl_llc2_p_timeout;
 892
 893        timer_setup(&llc->rej_sent_timer.timer, llc_conn_rej_tmr_cb, 0);
 894        llc->rej_sent_timer.expire         = sysctl_llc2_rej_timeout;
 895
 896        timer_setup(&llc->busy_state_timer.timer, llc_conn_busy_tmr_cb, 0);
 897        llc->busy_state_timer.expire         = sysctl_llc2_busy_timeout;
 898
 899        llc->n2 = 2;   /* max retransmit */
 900        llc->k  = 2;   /* tx win size, will adjust dynam */
 901        llc->rw = 128; /* rx win size (opt and equal to
 902                        * tx_win of remote LLC) */
 903        skb_queue_head_init(&llc->pdu_unack_q);
 904        sk->sk_backlog_rcv = llc_backlog_rcv;
 905}
 906
 907/**
 908 *      llc_sk_alloc - Allocates LLC sock
 909 *      @net: network namespace
 910 *      @family: upper layer protocol family
 911 *      @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
 912 *      @prot: struct proto associated with this new sock instance
 913 *      @kern: is this to be a kernel socket?
 914 *
 915 *      Allocates a LLC sock and initializes it. Returns the new LLC sock
 916 *      or %NULL if there's no memory available for one
 917 */
 918struct sock *llc_sk_alloc(struct net *net, int family, gfp_t priority, struct proto *prot, int kern)
 919{
 920        struct sock *sk = sk_alloc(net, family, priority, prot, kern);
 921
 922        if (!sk)
 923                goto out;
 924        llc_sk_init(sk);
 925        sock_init_data(NULL, sk);
 926#ifdef LLC_REFCNT_DEBUG
 927        atomic_inc(&llc_sock_nr);
 928        printk(KERN_DEBUG "LLC socket %p created in %s, now we have %d alive\n", sk,
 929                __func__, atomic_read(&llc_sock_nr));
 930#endif
 931out:
 932        return sk;
 933}
 934
 935void llc_sk_stop_all_timers(struct sock *sk, bool sync)
 936{
 937        struct llc_sock *llc = llc_sk(sk);
 938
 939        if (sync) {
 940                del_timer_sync(&llc->pf_cycle_timer.timer);
 941                del_timer_sync(&llc->ack_timer.timer);
 942                del_timer_sync(&llc->rej_sent_timer.timer);
 943                del_timer_sync(&llc->busy_state_timer.timer);
 944        } else {
 945                del_timer(&llc->pf_cycle_timer.timer);
 946                del_timer(&llc->ack_timer.timer);
 947                del_timer(&llc->rej_sent_timer.timer);
 948                del_timer(&llc->busy_state_timer.timer);
 949        }
 950
 951        llc->ack_must_be_send = 0;
 952        llc->ack_pf = 0;
 953}
 954
 955/**
 956 *      llc_sk_free - Frees a LLC socket
 957 *      @sk: - socket to free
 958 *
 959 *      Frees a LLC socket
 960 */
 961void llc_sk_free(struct sock *sk)
 962{
 963        struct llc_sock *llc = llc_sk(sk);
 964
 965        llc->state = LLC_CONN_OUT_OF_SVC;
 966        /* Stop all (possibly) running timers */
 967        llc_sk_stop_all_timers(sk, true);
 968#ifdef DEBUG_LLC_CONN_ALLOC
 969        printk(KERN_INFO "%s: unackq=%d, txq=%d\n", __func__,
 970                skb_queue_len(&llc->pdu_unack_q),
 971                skb_queue_len(&sk->sk_write_queue));
 972#endif
 973        skb_queue_purge(&sk->sk_receive_queue);
 974        skb_queue_purge(&sk->sk_write_queue);
 975        skb_queue_purge(&llc->pdu_unack_q);
 976#ifdef LLC_REFCNT_DEBUG
 977        if (refcount_read(&sk->sk_refcnt) != 1) {
 978                printk(KERN_DEBUG "Destruction of LLC sock %p delayed in %s, cnt=%d\n",
 979                        sk, __func__, refcount_read(&sk->sk_refcnt));
 980                printk(KERN_DEBUG "%d LLC sockets are still alive\n",
 981                        atomic_read(&llc_sock_nr));
 982        } else {
 983                atomic_dec(&llc_sock_nr);
 984                printk(KERN_DEBUG "LLC socket %p released in %s, %d are still alive\n", sk,
 985                        __func__, atomic_read(&llc_sock_nr));
 986        }
 987#endif
 988        sock_put(sk);
 989}
 990
 991/**
 992 *      llc_sk_reset - resets a connection
 993 *      @sk: LLC socket to reset
 994 *
 995 *      Resets a connection to the out of service state. Stops its timers
 996 *      and frees any frames in the queues of the connection.
 997 */
 998void llc_sk_reset(struct sock *sk)
 999{
1000        struct llc_sock *llc = llc_sk(sk);
1001
1002        llc_conn_ac_stop_all_timers(sk, NULL);
1003        skb_queue_purge(&sk->sk_write_queue);
1004        skb_queue_purge(&llc->pdu_unack_q);
1005        llc->remote_busy_flag   = 0;
1006        llc->cause_flag         = 0;
1007        llc->retry_count        = 0;
1008        llc_conn_set_p_flag(sk, 0);
1009        llc->f_flag             = 0;
1010        llc->s_flag             = 0;
1011        llc->ack_pf             = 0;
1012        llc->first_pdu_Ns       = 0;
1013        llc->ack_must_be_send   = 0;
1014        llc->dec_step           = 1;
1015        llc->inc_cntr           = 2;
1016        llc->dec_cntr           = 2;
1017        llc->X                  = 0;
1018        llc->failed_data_req    = 0 ;
1019        llc->last_nr            = 0;
1020}
1021