linux/net/decnet/dn_nsp_in.c
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   1/*
   2 * DECnet       An implementation of the DECnet protocol suite for the LINUX
   3 *              operating system.  DECnet is implemented using the  BSD Socket
   4 *              interface as the means of communication with the user level.
   5 *
   6 *              DECnet Network Services Protocol (Input)
   7 *
   8 * Author:      Eduardo Marcelo Serrat <emserrat@geocities.com>
   9 *
  10 * Changes:
  11 *
  12 *    Steve Whitehouse:  Split into dn_nsp_in.c and dn_nsp_out.c from
  13 *                       original dn_nsp.c.
  14 *    Steve Whitehouse:  Updated to work with my new routing architecture.
  15 *    Steve Whitehouse:  Add changes from Eduardo Serrat's patches.
  16 *    Steve Whitehouse:  Put all ack handling code in a common routine.
  17 *    Steve Whitehouse:  Put other common bits into dn_nsp_rx()
  18 *    Steve Whitehouse:  More checks on skb->len to catch bogus packets
  19 *                       Fixed various race conditions and possible nasties.
  20 *    Steve Whitehouse:  Now handles returned conninit frames.
  21 *     David S. Miller:  New socket locking
  22 *    Steve Whitehouse:  Fixed lockup when socket filtering was enabled.
  23 *         Paul Koning:  Fix to push CC sockets into RUN when acks are
  24 *                       received.
  25 *    Steve Whitehouse:
  26 *   Patrick Caulfield:  Checking conninits for correctness & sending of error
  27 *                       responses.
  28 *    Steve Whitehouse:  Added backlog congestion level return codes.
  29 *   Patrick Caulfield:
  30 *    Steve Whitehouse:  Added flow control support (outbound)
  31 *    Steve Whitehouse:  Prepare for nonlinear skbs
  32 */
  33
  34/******************************************************************************
  35    (c) 1995-1998 E.M. Serrat           emserrat@geocities.com
  36
  37    This program is free software; you can redistribute it and/or modify
  38    it under the terms of the GNU General Public License as published by
  39    the Free Software Foundation; either version 2 of the License, or
  40    any later version.
  41
  42    This program is distributed in the hope that it will be useful,
  43    but WITHOUT ANY WARRANTY; without even the implied warranty of
  44    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  45    GNU General Public License for more details.
  46*******************************************************************************/
  47
  48#include <linux/errno.h>
  49#include <linux/types.h>
  50#include <linux/socket.h>
  51#include <linux/in.h>
  52#include <linux/kernel.h>
  53#include <linux/timer.h>
  54#include <linux/string.h>
  55#include <linux/sockios.h>
  56#include <linux/net.h>
  57#include <linux/netdevice.h>
  58#include <linux/inet.h>
  59#include <linux/route.h>
  60#include <linux/slab.h>
  61#include <net/sock.h>
  62#include <net/tcp_states.h>
  63#include <linux/fcntl.h>
  64#include <linux/mm.h>
  65#include <linux/termios.h>
  66#include <linux/interrupt.h>
  67#include <linux/proc_fs.h>
  68#include <linux/stat.h>
  69#include <linux/init.h>
  70#include <linux/poll.h>
  71#include <linux/netfilter_decnet.h>
  72#include <net/neighbour.h>
  73#include <net/dst.h>
  74#include <net/dn.h>
  75#include <net/dn_nsp.h>
  76#include <net/dn_dev.h>
  77#include <net/dn_route.h>
  78
  79extern int decnet_log_martians;
  80
  81static void dn_log_martian(struct sk_buff *skb, const char *msg)
  82{
  83        if (decnet_log_martians) {
  84                char *devname = skb->dev ? skb->dev->name : "???";
  85                struct dn_skb_cb *cb = DN_SKB_CB(skb);
  86                net_info_ratelimited("DECnet: Martian packet (%s) dev=%s src=0x%04hx dst=0x%04hx srcport=0x%04hx dstport=0x%04hx\n",
  87                                     msg, devname,
  88                                     le16_to_cpu(cb->src),
  89                                     le16_to_cpu(cb->dst),
  90                                     le16_to_cpu(cb->src_port),
  91                                     le16_to_cpu(cb->dst_port));
  92        }
  93}
  94
  95/*
  96 * For this function we've flipped the cross-subchannel bit
  97 * if the message is an otherdata or linkservice message. Thus
  98 * we can use it to work out what to update.
  99 */
 100static void dn_ack(struct sock *sk, struct sk_buff *skb, unsigned short ack)
 101{
 102        struct dn_scp *scp = DN_SK(sk);
 103        unsigned short type = ((ack >> 12) & 0x0003);
 104        int wakeup = 0;
 105
 106        switch (type) {
 107        case 0: /* ACK - Data */
 108                if (dn_after(ack, scp->ackrcv_dat)) {
 109                        scp->ackrcv_dat = ack & 0x0fff;
 110                        wakeup |= dn_nsp_check_xmit_queue(sk, skb,
 111                                                          &scp->data_xmit_queue,
 112                                                          ack);
 113                }
 114                break;
 115        case 1: /* NAK - Data */
 116                break;
 117        case 2: /* ACK - OtherData */
 118                if (dn_after(ack, scp->ackrcv_oth)) {
 119                        scp->ackrcv_oth = ack & 0x0fff;
 120                        wakeup |= dn_nsp_check_xmit_queue(sk, skb,
 121                                                          &scp->other_xmit_queue,
 122                                                          ack);
 123                }
 124                break;
 125        case 3: /* NAK - OtherData */
 126                break;
 127        }
 128
 129        if (wakeup && !sock_flag(sk, SOCK_DEAD))
 130                sk->sk_state_change(sk);
 131}
 132
 133/*
 134 * This function is a universal ack processor.
 135 */
 136static int dn_process_ack(struct sock *sk, struct sk_buff *skb, int oth)
 137{
 138        __le16 *ptr = (__le16 *)skb->data;
 139        int len = 0;
 140        unsigned short ack;
 141
 142        if (skb->len < 2)
 143                return len;
 144
 145        if ((ack = le16_to_cpu(*ptr)) & 0x8000) {
 146                skb_pull(skb, 2);
 147                ptr++;
 148                len += 2;
 149                if ((ack & 0x4000) == 0) {
 150                        if (oth)
 151                                ack ^= 0x2000;
 152                        dn_ack(sk, skb, ack);
 153                }
 154        }
 155
 156        if (skb->len < 2)
 157                return len;
 158
 159        if ((ack = le16_to_cpu(*ptr)) & 0x8000) {
 160                skb_pull(skb, 2);
 161                len += 2;
 162                if ((ack & 0x4000) == 0) {
 163                        if (oth)
 164                                ack ^= 0x2000;
 165                        dn_ack(sk, skb, ack);
 166                }
 167        }
 168
 169        return len;
 170}
 171
 172
 173/**
 174 * dn_check_idf - Check an image data field format is correct.
 175 * @pptr: Pointer to pointer to image data
 176 * @len: Pointer to length of image data
 177 * @max: The maximum allowed length of the data in the image data field
 178 * @follow_on: Check that this many bytes exist beyond the end of the image data
 179 *
 180 * Returns: 0 if ok, -1 on error
 181 */
 182static inline int dn_check_idf(unsigned char **pptr, int *len, unsigned char max, unsigned char follow_on)
 183{
 184        unsigned char *ptr = *pptr;
 185        unsigned char flen = *ptr++;
 186
 187        (*len)--;
 188        if (flen > max)
 189                return -1;
 190        if ((flen + follow_on) > *len)
 191                return -1;
 192
 193        *len -= flen;
 194        *pptr = ptr + flen;
 195        return 0;
 196}
 197
 198/*
 199 * Table of reason codes to pass back to node which sent us a badly
 200 * formed message, plus text messages for the log. A zero entry in
 201 * the reason field means "don't reply" otherwise a disc init is sent with
 202 * the specified reason code.
 203 */
 204static struct {
 205        unsigned short reason;
 206        const char *text;
 207} ci_err_table[] = {
 208 { 0,             "CI: Truncated message" },
 209 { NSP_REASON_ID, "CI: Destination username error" },
 210 { NSP_REASON_ID, "CI: Destination username type" },
 211 { NSP_REASON_US, "CI: Source username error" },
 212 { 0,             "CI: Truncated at menuver" },
 213 { 0,             "CI: Truncated before access or user data" },
 214 { NSP_REASON_IO, "CI: Access data format error" },
 215 { NSP_REASON_IO, "CI: User data format error" }
 216};
 217
 218/*
 219 * This function uses a slightly different lookup method
 220 * to find its sockets, since it searches on object name/number
 221 * rather than port numbers. Various tests are done to ensure that
 222 * the incoming data is in the correct format before it is queued to
 223 * a socket.
 224 */
 225static struct sock *dn_find_listener(struct sk_buff *skb, unsigned short *reason)
 226{
 227        struct dn_skb_cb *cb = DN_SKB_CB(skb);
 228        struct nsp_conn_init_msg *msg = (struct nsp_conn_init_msg *)skb->data;
 229        struct sockaddr_dn dstaddr;
 230        struct sockaddr_dn srcaddr;
 231        unsigned char type = 0;
 232        int dstlen;
 233        int srclen;
 234        unsigned char *ptr;
 235        int len;
 236        int err = 0;
 237        unsigned char menuver;
 238
 239        memset(&dstaddr, 0, sizeof(struct sockaddr_dn));
 240        memset(&srcaddr, 0, sizeof(struct sockaddr_dn));
 241
 242        /*
 243         * 1. Decode & remove message header
 244         */
 245        cb->src_port = msg->srcaddr;
 246        cb->dst_port = msg->dstaddr;
 247        cb->services = msg->services;
 248        cb->info     = msg->info;
 249        cb->segsize  = le16_to_cpu(msg->segsize);
 250
 251        if (!pskb_may_pull(skb, sizeof(*msg)))
 252                goto err_out;
 253
 254        skb_pull(skb, sizeof(*msg));
 255
 256        len = skb->len;
 257        ptr = skb->data;
 258
 259        /*
 260         * 2. Check destination end username format
 261         */
 262        dstlen = dn_username2sockaddr(ptr, len, &dstaddr, &type);
 263        err++;
 264        if (dstlen < 0)
 265                goto err_out;
 266
 267        err++;
 268        if (type > 1)
 269                goto err_out;
 270
 271        len -= dstlen;
 272        ptr += dstlen;
 273
 274        /*
 275         * 3. Check source end username format
 276         */
 277        srclen = dn_username2sockaddr(ptr, len, &srcaddr, &type);
 278        err++;
 279        if (srclen < 0)
 280                goto err_out;
 281
 282        len -= srclen;
 283        ptr += srclen;
 284        err++;
 285        if (len < 1)
 286                goto err_out;
 287
 288        menuver = *ptr;
 289        ptr++;
 290        len--;
 291
 292        /*
 293         * 4. Check that optional data actually exists if menuver says it does
 294         */
 295        err++;
 296        if ((menuver & (DN_MENUVER_ACC | DN_MENUVER_USR)) && (len < 1))
 297                goto err_out;
 298
 299        /*
 300         * 5. Check optional access data format
 301         */
 302        err++;
 303        if (menuver & DN_MENUVER_ACC) {
 304                if (dn_check_idf(&ptr, &len, 39, 1))
 305                        goto err_out;
 306                if (dn_check_idf(&ptr, &len, 39, 1))
 307                        goto err_out;
 308                if (dn_check_idf(&ptr, &len, 39, (menuver & DN_MENUVER_USR) ? 1 : 0))
 309                        goto err_out;
 310        }
 311
 312        /*
 313         * 6. Check optional user data format
 314         */
 315        err++;
 316        if (menuver & DN_MENUVER_USR) {
 317                if (dn_check_idf(&ptr, &len, 16, 0))
 318                        goto err_out;
 319        }
 320
 321        /*
 322         * 7. Look up socket based on destination end username
 323         */
 324        return dn_sklist_find_listener(&dstaddr);
 325err_out:
 326        dn_log_martian(skb, ci_err_table[err].text);
 327        *reason = ci_err_table[err].reason;
 328        return NULL;
 329}
 330
 331
 332static void dn_nsp_conn_init(struct sock *sk, struct sk_buff *skb)
 333{
 334        if (sk_acceptq_is_full(sk)) {
 335                kfree_skb(skb);
 336                return;
 337        }
 338
 339        sk->sk_ack_backlog++;
 340        skb_queue_tail(&sk->sk_receive_queue, skb);
 341        sk->sk_state_change(sk);
 342}
 343
 344static void dn_nsp_conn_conf(struct sock *sk, struct sk_buff *skb)
 345{
 346        struct dn_skb_cb *cb = DN_SKB_CB(skb);
 347        struct dn_scp *scp = DN_SK(sk);
 348        unsigned char *ptr;
 349
 350        if (skb->len < 4)
 351                goto out;
 352
 353        ptr = skb->data;
 354        cb->services = *ptr++;
 355        cb->info = *ptr++;
 356        cb->segsize = le16_to_cpu(*(__le16 *)ptr);
 357
 358        if ((scp->state == DN_CI) || (scp->state == DN_CD)) {
 359                scp->persist = 0;
 360                scp->addrrem = cb->src_port;
 361                sk->sk_state = TCP_ESTABLISHED;
 362                scp->state = DN_RUN;
 363                scp->services_rem = cb->services;
 364                scp->info_rem = cb->info;
 365                scp->segsize_rem = cb->segsize;
 366
 367                if ((scp->services_rem & NSP_FC_MASK) == NSP_FC_NONE)
 368                        scp->max_window = decnet_no_fc_max_cwnd;
 369
 370                if (skb->len > 0) {
 371                        u16 dlen = *skb->data;
 372                        if ((dlen <= 16) && (dlen <= skb->len)) {
 373                                scp->conndata_in.opt_optl = cpu_to_le16(dlen);
 374                                skb_copy_from_linear_data_offset(skb, 1,
 375                                              scp->conndata_in.opt_data, dlen);
 376                        }
 377                }
 378                dn_nsp_send_link(sk, DN_NOCHANGE, 0);
 379                if (!sock_flag(sk, SOCK_DEAD))
 380                        sk->sk_state_change(sk);
 381        }
 382
 383out:
 384        kfree_skb(skb);
 385}
 386
 387static void dn_nsp_conn_ack(struct sock *sk, struct sk_buff *skb)
 388{
 389        struct dn_scp *scp = DN_SK(sk);
 390
 391        if (scp->state == DN_CI) {
 392                scp->state = DN_CD;
 393                scp->persist = 0;
 394        }
 395
 396        kfree_skb(skb);
 397}
 398
 399static void dn_nsp_disc_init(struct sock *sk, struct sk_buff *skb)
 400{
 401        struct dn_scp *scp = DN_SK(sk);
 402        struct dn_skb_cb *cb = DN_SKB_CB(skb);
 403        unsigned short reason;
 404
 405        if (skb->len < 2)
 406                goto out;
 407
 408        reason = le16_to_cpu(*(__le16 *)skb->data);
 409        skb_pull(skb, 2);
 410
 411        scp->discdata_in.opt_status = cpu_to_le16(reason);
 412        scp->discdata_in.opt_optl   = 0;
 413        memset(scp->discdata_in.opt_data, 0, 16);
 414
 415        if (skb->len > 0) {
 416                u16 dlen = *skb->data;
 417                if ((dlen <= 16) && (dlen <= skb->len)) {
 418                        scp->discdata_in.opt_optl = cpu_to_le16(dlen);
 419                        skb_copy_from_linear_data_offset(skb, 1, scp->discdata_in.opt_data, dlen);
 420                }
 421        }
 422
 423        scp->addrrem = cb->src_port;
 424        sk->sk_state = TCP_CLOSE;
 425
 426        switch (scp->state) {
 427        case DN_CI:
 428        case DN_CD:
 429                scp->state = DN_RJ;
 430                sk->sk_err = ECONNREFUSED;
 431                break;
 432        case DN_RUN:
 433                sk->sk_shutdown |= SHUTDOWN_MASK;
 434                scp->state = DN_DN;
 435                break;
 436        case DN_DI:
 437                scp->state = DN_DIC;
 438                break;
 439        }
 440
 441        if (!sock_flag(sk, SOCK_DEAD)) {
 442                if (sk->sk_socket->state != SS_UNCONNECTED)
 443                        sk->sk_socket->state = SS_DISCONNECTING;
 444                sk->sk_state_change(sk);
 445        }
 446
 447        /*
 448         * It appears that its possible for remote machines to send disc
 449         * init messages with no port identifier if we are in the CI and
 450         * possibly also the CD state. Obviously we shouldn't reply with
 451         * a message if we don't know what the end point is.
 452         */
 453        if (scp->addrrem) {
 454                dn_nsp_send_disc(sk, NSP_DISCCONF, NSP_REASON_DC, GFP_ATOMIC);
 455        }
 456        scp->persist_fxn = dn_destroy_timer;
 457        scp->persist = dn_nsp_persist(sk);
 458
 459out:
 460        kfree_skb(skb);
 461}
 462
 463/*
 464 * disc_conf messages are also called no_resources or no_link
 465 * messages depending upon the "reason" field.
 466 */
 467static void dn_nsp_disc_conf(struct sock *sk, struct sk_buff *skb)
 468{
 469        struct dn_scp *scp = DN_SK(sk);
 470        unsigned short reason;
 471
 472        if (skb->len != 2)
 473                goto out;
 474
 475        reason = le16_to_cpu(*(__le16 *)skb->data);
 476
 477        sk->sk_state = TCP_CLOSE;
 478
 479        switch (scp->state) {
 480        case DN_CI:
 481                scp->state = DN_NR;
 482                break;
 483        case DN_DR:
 484                if (reason == NSP_REASON_DC)
 485                        scp->state = DN_DRC;
 486                if (reason == NSP_REASON_NL)
 487                        scp->state = DN_CN;
 488                break;
 489        case DN_DI:
 490                scp->state = DN_DIC;
 491                break;
 492        case DN_RUN:
 493                sk->sk_shutdown |= SHUTDOWN_MASK;
 494        case DN_CC:
 495                scp->state = DN_CN;
 496        }
 497
 498        if (!sock_flag(sk, SOCK_DEAD)) {
 499                if (sk->sk_socket->state != SS_UNCONNECTED)
 500                        sk->sk_socket->state = SS_DISCONNECTING;
 501                sk->sk_state_change(sk);
 502        }
 503
 504        scp->persist_fxn = dn_destroy_timer;
 505        scp->persist = dn_nsp_persist(sk);
 506
 507out:
 508        kfree_skb(skb);
 509}
 510
 511static void dn_nsp_linkservice(struct sock *sk, struct sk_buff *skb)
 512{
 513        struct dn_scp *scp = DN_SK(sk);
 514        unsigned short segnum;
 515        unsigned char lsflags;
 516        signed char fcval;
 517        int wake_up = 0;
 518        char *ptr = skb->data;
 519        unsigned char fctype = scp->services_rem & NSP_FC_MASK;
 520
 521        if (skb->len != 4)
 522                goto out;
 523
 524        segnum = le16_to_cpu(*(__le16 *)ptr);
 525        ptr += 2;
 526        lsflags = *(unsigned char *)ptr++;
 527        fcval = *ptr;
 528
 529        /*
 530         * Here we ignore erronous packets which should really
 531         * should cause a connection abort. It is not critical
 532         * for now though.
 533         */
 534        if (lsflags & 0xf8)
 535                goto out;
 536
 537        if (seq_next(scp->numoth_rcv, segnum)) {
 538                seq_add(&scp->numoth_rcv, 1);
 539                switch(lsflags & 0x04) { /* FCVAL INT */
 540                case 0x00: /* Normal Request */
 541                        switch(lsflags & 0x03) { /* FCVAL MOD */
 542                        case 0x00: /* Request count */
 543                                if (fcval < 0) {
 544                                        unsigned char p_fcval = -fcval;
 545                                        if ((scp->flowrem_dat > p_fcval) &&
 546                                            (fctype == NSP_FC_SCMC)) {
 547                                                scp->flowrem_dat -= p_fcval;
 548                                        }
 549                                } else if (fcval > 0) {
 550                                        scp->flowrem_dat += fcval;
 551                                        wake_up = 1;
 552                                }
 553                                break;
 554                        case 0x01: /* Stop outgoing data */
 555                                scp->flowrem_sw = DN_DONTSEND;
 556                                break;
 557                        case 0x02: /* Ok to start again */
 558                                scp->flowrem_sw = DN_SEND;
 559                                dn_nsp_output(sk);
 560                                wake_up = 1;
 561                        }
 562                        break;
 563                case 0x04: /* Interrupt Request */
 564                        if (fcval > 0) {
 565                                scp->flowrem_oth += fcval;
 566                                wake_up = 1;
 567                        }
 568                        break;
 569                }
 570                if (wake_up && !sock_flag(sk, SOCK_DEAD))
 571                        sk->sk_state_change(sk);
 572        }
 573
 574        dn_nsp_send_oth_ack(sk);
 575
 576out:
 577        kfree_skb(skb);
 578}
 579
 580/*
 581 * Copy of sock_queue_rcv_skb (from sock.h) without
 582 * bh_lock_sock() (its already held when this is called) which
 583 * also allows data and other data to be queued to a socket.
 584 */
 585static __inline__ int dn_queue_skb(struct sock *sk, struct sk_buff *skb, int sig, struct sk_buff_head *queue)
 586{
 587        int err;
 588        int skb_len;
 589
 590        /* Cast skb->rcvbuf to unsigned... It's pointless, but reduces
 591           number of warnings when compiling with -W --ANK
 592         */
 593        if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
 594            (unsigned int)sk->sk_rcvbuf) {
 595                err = -ENOMEM;
 596                goto out;
 597        }
 598
 599        err = sk_filter(sk, skb);
 600        if (err)
 601                goto out;
 602
 603        skb_len = skb->len;
 604        skb_set_owner_r(skb, sk);
 605        skb_queue_tail(queue, skb);
 606
 607        if (!sock_flag(sk, SOCK_DEAD))
 608                sk->sk_data_ready(sk, skb_len);
 609out:
 610        return err;
 611}
 612
 613static void dn_nsp_otherdata(struct sock *sk, struct sk_buff *skb)
 614{
 615        struct dn_scp *scp = DN_SK(sk);
 616        unsigned short segnum;
 617        struct dn_skb_cb *cb = DN_SKB_CB(skb);
 618        int queued = 0;
 619
 620        if (skb->len < 2)
 621                goto out;
 622
 623        cb->segnum = segnum = le16_to_cpu(*(__le16 *)skb->data);
 624        skb_pull(skb, 2);
 625
 626        if (seq_next(scp->numoth_rcv, segnum)) {
 627
 628                if (dn_queue_skb(sk, skb, SIGURG, &scp->other_receive_queue) == 0) {
 629                        seq_add(&scp->numoth_rcv, 1);
 630                        scp->other_report = 0;
 631                        queued = 1;
 632                }
 633        }
 634
 635        dn_nsp_send_oth_ack(sk);
 636out:
 637        if (!queued)
 638                kfree_skb(skb);
 639}
 640
 641static void dn_nsp_data(struct sock *sk, struct sk_buff *skb)
 642{
 643        int queued = 0;
 644        unsigned short segnum;
 645        struct dn_skb_cb *cb = DN_SKB_CB(skb);
 646        struct dn_scp *scp = DN_SK(sk);
 647
 648        if (skb->len < 2)
 649                goto out;
 650
 651        cb->segnum = segnum = le16_to_cpu(*(__le16 *)skb->data);
 652        skb_pull(skb, 2);
 653
 654        if (seq_next(scp->numdat_rcv, segnum)) {
 655                if (dn_queue_skb(sk, skb, SIGIO, &sk->sk_receive_queue) == 0) {
 656                        seq_add(&scp->numdat_rcv, 1);
 657                        queued = 1;
 658                }
 659
 660                if ((scp->flowloc_sw == DN_SEND) && dn_congested(sk)) {
 661                        scp->flowloc_sw = DN_DONTSEND;
 662                        dn_nsp_send_link(sk, DN_DONTSEND, 0);
 663                }
 664        }
 665
 666        dn_nsp_send_data_ack(sk);
 667out:
 668        if (!queued)
 669                kfree_skb(skb);
 670}
 671
 672/*
 673 * If one of our conninit messages is returned, this function
 674 * deals with it. It puts the socket into the NO_COMMUNICATION
 675 * state.
 676 */
 677static void dn_returned_conn_init(struct sock *sk, struct sk_buff *skb)
 678{
 679        struct dn_scp *scp = DN_SK(sk);
 680
 681        if (scp->state == DN_CI) {
 682                scp->state = DN_NC;
 683                sk->sk_state = TCP_CLOSE;
 684                if (!sock_flag(sk, SOCK_DEAD))
 685                        sk->sk_state_change(sk);
 686        }
 687
 688        kfree_skb(skb);
 689}
 690
 691static int dn_nsp_no_socket(struct sk_buff *skb, unsigned short reason)
 692{
 693        struct dn_skb_cb *cb = DN_SKB_CB(skb);
 694        int ret = NET_RX_DROP;
 695
 696        /* Must not reply to returned packets */
 697        if (cb->rt_flags & DN_RT_F_RTS)
 698                goto out;
 699
 700        if ((reason != NSP_REASON_OK) && ((cb->nsp_flags & 0x0c) == 0x08)) {
 701                switch (cb->nsp_flags & 0x70) {
 702                case 0x10:
 703                case 0x60: /* (Retransmitted) Connect Init */
 704                        dn_nsp_return_disc(skb, NSP_DISCINIT, reason);
 705                        ret = NET_RX_SUCCESS;
 706                        break;
 707                case 0x20: /* Connect Confirm */
 708                        dn_nsp_return_disc(skb, NSP_DISCCONF, reason);
 709                        ret = NET_RX_SUCCESS;
 710                        break;
 711                }
 712        }
 713
 714out:
 715        kfree_skb(skb);
 716        return ret;
 717}
 718
 719static int dn_nsp_rx_packet(struct sk_buff *skb)
 720{
 721        struct dn_skb_cb *cb = DN_SKB_CB(skb);
 722        struct sock *sk = NULL;
 723        unsigned char *ptr = (unsigned char *)skb->data;
 724        unsigned short reason = NSP_REASON_NL;
 725
 726        if (!pskb_may_pull(skb, 2))
 727                goto free_out;
 728
 729        skb_reset_transport_header(skb);
 730        cb->nsp_flags = *ptr++;
 731
 732        if (decnet_debug_level & 2)
 733                printk(KERN_DEBUG "dn_nsp_rx: Message type 0x%02x\n", (int)cb->nsp_flags);
 734
 735        if (cb->nsp_flags & 0x83)
 736                goto free_out;
 737
 738        /*
 739         * Filter out conninits and useless packet types
 740         */
 741        if ((cb->nsp_flags & 0x0c) == 0x08) {
 742                switch (cb->nsp_flags & 0x70) {
 743                case 0x00: /* NOP */
 744                case 0x70: /* Reserved */
 745                case 0x50: /* Reserved, Phase II node init */
 746                        goto free_out;
 747                case 0x10:
 748                case 0x60:
 749                        if (unlikely(cb->rt_flags & DN_RT_F_RTS))
 750                                goto free_out;
 751                        sk = dn_find_listener(skb, &reason);
 752                        goto got_it;
 753                }
 754        }
 755
 756        if (!pskb_may_pull(skb, 3))
 757                goto free_out;
 758
 759        /*
 760         * Grab the destination address.
 761         */
 762        cb->dst_port = *(__le16 *)ptr;
 763        cb->src_port = 0;
 764        ptr += 2;
 765
 766        /*
 767         * If not a connack, grab the source address too.
 768         */
 769        if (pskb_may_pull(skb, 5)) {
 770                cb->src_port = *(__le16 *)ptr;
 771                ptr += 2;
 772                skb_pull(skb, 5);
 773        }
 774
 775        /*
 776         * Returned packets...
 777         * Swap src & dst and look up in the normal way.
 778         */
 779        if (unlikely(cb->rt_flags & DN_RT_F_RTS)) {
 780                __le16 tmp = cb->dst_port;
 781                cb->dst_port = cb->src_port;
 782                cb->src_port = tmp;
 783                tmp = cb->dst;
 784                cb->dst = cb->src;
 785                cb->src = tmp;
 786        }
 787
 788        /*
 789         * Find the socket to which this skb is destined.
 790         */
 791        sk = dn_find_by_skb(skb);
 792got_it:
 793        if (sk != NULL) {
 794                struct dn_scp *scp = DN_SK(sk);
 795
 796                /* Reset backoff */
 797                scp->nsp_rxtshift = 0;
 798
 799                /*
 800                 * We linearize everything except data segments here.
 801                 */
 802                if (cb->nsp_flags & ~0x60) {
 803                        if (unlikely(skb_linearize(skb)))
 804                                goto free_out;
 805                }
 806
 807                return sk_receive_skb(sk, skb, 0);
 808        }
 809
 810        return dn_nsp_no_socket(skb, reason);
 811
 812free_out:
 813        kfree_skb(skb);
 814        return NET_RX_DROP;
 815}
 816
 817int dn_nsp_rx(struct sk_buff *skb)
 818{
 819        return NF_HOOK(NFPROTO_DECNET, NF_DN_LOCAL_IN, skb, skb->dev, NULL,
 820                       dn_nsp_rx_packet);
 821}
 822
 823/*
 824 * This is the main receive routine for sockets. It is called
 825 * from the above when the socket is not busy, and also from
 826 * sock_release() when there is a backlog queued up.
 827 */
 828int dn_nsp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 829{
 830        struct dn_scp *scp = DN_SK(sk);
 831        struct dn_skb_cb *cb = DN_SKB_CB(skb);
 832
 833        if (cb->rt_flags & DN_RT_F_RTS) {
 834                if (cb->nsp_flags == 0x18 || cb->nsp_flags == 0x68)
 835                        dn_returned_conn_init(sk, skb);
 836                else
 837                        kfree_skb(skb);
 838                return NET_RX_SUCCESS;
 839        }
 840
 841        /*
 842         * Control packet.
 843         */
 844        if ((cb->nsp_flags & 0x0c) == 0x08) {
 845                switch (cb->nsp_flags & 0x70) {
 846                case 0x10:
 847                case 0x60:
 848                        dn_nsp_conn_init(sk, skb);
 849                        break;
 850                case 0x20:
 851                        dn_nsp_conn_conf(sk, skb);
 852                        break;
 853                case 0x30:
 854                        dn_nsp_disc_init(sk, skb);
 855                        break;
 856                case 0x40:
 857                        dn_nsp_disc_conf(sk, skb);
 858                        break;
 859                }
 860
 861        } else if (cb->nsp_flags == 0x24) {
 862                /*
 863                 * Special for connacks, 'cos they don't have
 864                 * ack data or ack otherdata info.
 865                 */
 866                dn_nsp_conn_ack(sk, skb);
 867        } else {
 868                int other = 1;
 869
 870                /* both data and ack frames can kick a CC socket into RUN */
 871                if ((scp->state == DN_CC) && !sock_flag(sk, SOCK_DEAD)) {
 872                        scp->state = DN_RUN;
 873                        sk->sk_state = TCP_ESTABLISHED;
 874                        sk->sk_state_change(sk);
 875                }
 876
 877                if ((cb->nsp_flags & 0x1c) == 0)
 878                        other = 0;
 879                if (cb->nsp_flags == 0x04)
 880                        other = 0;
 881
 882                /*
 883                 * Read out ack data here, this applies equally
 884                 * to data, other data, link serivce and both
 885                 * ack data and ack otherdata.
 886                 */
 887                dn_process_ack(sk, skb, other);
 888
 889                /*
 890                 * If we've some sort of data here then call a
 891                 * suitable routine for dealing with it, otherwise
 892                 * the packet is an ack and can be discarded.
 893                 */
 894                if ((cb->nsp_flags & 0x0c) == 0) {
 895
 896                        if (scp->state != DN_RUN)
 897                                goto free_out;
 898
 899                        switch (cb->nsp_flags) {
 900                        case 0x10: /* LS */
 901                                dn_nsp_linkservice(sk, skb);
 902                                break;
 903                        case 0x30: /* OD */
 904                                dn_nsp_otherdata(sk, skb);
 905                                break;
 906                        default:
 907                                dn_nsp_data(sk, skb);
 908                        }
 909
 910                } else { /* Ack, chuck it out here */
 911free_out:
 912                        kfree_skb(skb);
 913                }
 914        }
 915
 916        return NET_RX_SUCCESS;
 917}
 918
 919
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