net/decnet/dn_nsp_in.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * DECnet       An implementation of the DECnet protocol suite for the LINUX
   4  *              operating system.  DECnet is implemented using the  BSD Socket
   5  *              interface as the means of communication with the user level.
   6  *
   7  *              DECnet Network Services Protocol (Input)
   8  *
   9  * Author:      Eduardo Marcelo Serrat <emserrat@geocities.com>
  10  *
  11  * Changes:
  12  *
  13  *    Steve Whitehouse:  Split into dn_nsp_in.c and dn_nsp_out.c from
  14  *                       original dn_nsp.c.
  15  *    Steve Whitehouse:  Updated to work with my new routing architecture.
  16  *    Steve Whitehouse:  Add changes from Eduardo Serrat's patches.
  17  *    Steve Whitehouse:  Put all ack handling code in a common routine.
  18  *    Steve Whitehouse:  Put other common bits into dn_nsp_rx()
  19  *    Steve Whitehouse:  More checks on skb->len to catch bogus packets
  20  *                       Fixed various race conditions and possible nasties.
  21  *    Steve Whitehouse:  Now handles returned conninit frames.
  22  *     David S. Miller:  New socket locking
  23  *    Steve Whitehouse:  Fixed lockup when socket filtering was enabled.
  24  *         Paul Koning:  Fix to push CC sockets into RUN when acks are
  25  *                       received.
  26  *    Steve Whitehouse:
  27  *   Patrick Caulfield:  Checking conninits for correctness & sending of error
  28  *                       responses.
  29  *    Steve Whitehouse:  Added backlog congestion level return codes.
  30  *   Patrick Caulfield:
  31  *    Steve Whitehouse:  Added flow control support (outbound)
  32  *    Steve Whitehouse:  Prepare for nonlinear skbs
  33  */
  34
  35 /******************************************************************************
  36     (c) 1995-1998 E.M. Serrat           emserrat@geocities.com
  37
  38 *******************************************************************************/
  39
  40 #include <linux/errno.h>
  41 #include <linux/filter.h>
  42 #include <linux/types.h>
  43 #include <linux/socket.h>
  44 #include <linux/in.h>
  45 #include <linux/kernel.h>
  46 #include <linux/timer.h>
  47 #include <linux/string.h>
  48 #include <linux/sockios.h>
  49 #include <linux/net.h>
  50 #include <linux/netdevice.h>
  51 #include <linux/inet.h>
  52 #include <linux/route.h>
  53 #include <linux/slab.h>
  54 #include <net/sock.h>
  55 #include <net/tcp_states.h>
  56 #include <linux/fcntl.h>
  57 #include <linux/mm.h>
  58 #include <linux/termios.h>
  59 #include <linux/interrupt.h>
  60 #include <linux/proc_fs.h>
  61 #include <linux/stat.h>
  62 #include <linux/init.h>
  63 #include <linux/poll.h>
  64 #include <linux/netfilter_decnet.h>
  65 #include <net/neighbour.h>
  66 #include <net/dst.h>
  67 #include <net/dn.h>
  68 #include <net/dn_nsp.h>
  69 #include <net/dn_dev.h>
  70 #include <net/dn_route.h>
  71
  72 extern int decnet_log_martians;
  73
  74 static void dn_log_martian(struct sk_buff *skb, const char *msg)
  75 {
  76         if (decnet_log_martians) {
  77                 char *devname = skb->dev ? skb->dev->name : "???";
  78                 struct dn_skb_cb *cb = DN_SKB_CB(skb);
  79                 net_info_ratelimited("DECnet: Martian packet (%s) dev=%s src=0x%04hx dst=0x%04hx srcport=0x%04hx dstport=0x%04hx\n",
  80                                      msg, devname,
  81                                      le16_to_cpu(cb->src),
  82                                      le16_to_cpu(cb->dst),
  83                                      le16_to_cpu(cb->src_port),
  84                                      le16_to_cpu(cb->dst_port));
  85         }
  86 }
  87
  88 /*
  89  * For this function we've flipped the cross-subchannel bit
  90  * if the message is an otherdata or linkservice message. Thus
  91  * we can use it to work out what to update.
  92  */
  93 static void dn_ack(struct sock *sk, struct sk_buff *skb, unsigned short ack)
  94 {
  95         struct dn_scp *scp = DN_SK(sk);
  96         unsigned short type = ((ack >> 12) & 0x0003);
  97         int wakeup = 0;
  98
  99         switch (type) {
 100         case 0: /* ACK - Data */
 101                 if (dn_after(ack, scp->ackrcv_dat)) {
 102                         scp->ackrcv_dat = ack & 0x0fff;
 103                         wakeup |= dn_nsp_check_xmit_queue(sk, skb,
 104                                                           &scp->data_xmit_queue,
 105                                                           ack);
 106                 }
 107                 break;
 108         case 1: /* NAK - Data */
 109                 break;
 110         case 2: /* ACK - OtherData */
 111                 if (dn_after(ack, scp->ackrcv_oth)) {
 112                         scp->ackrcv_oth = ack & 0x0fff;
 113                         wakeup |= dn_nsp_check_xmit_queue(sk, skb,
 114                                                           &scp->other_xmit_queue,
 115                                                           ack);
 116                 }
 117                 break;
 118         case 3: /* NAK - OtherData */
 119                 break;
 120         }
 121
 122         if (wakeup && !sock_flag(sk, SOCK_DEAD))
 123                 sk->sk_state_change(sk);
 124 }
 125
 126 /*
 127  * This function is a universal ack processor.
 128  */
 129 static int dn_process_ack(struct sock *sk, struct sk_buff *skb, int oth)
 130 {
 131         __le16 *ptr = (__le16 *)skb->data;
 132         int len = 0;
 133         unsigned short ack;
 134
 135         if (skb->len < 2)
 136                 return len;
 137
 138         if ((ack = le16_to_cpu(*ptr)) & 0x8000) {
 139                 skb_pull(skb, 2);
 140                 ptr++;
 141                 len += 2;
 142                 if ((ack & 0x4000) == 0) {
 143                         if (oth)
 144                                 ack ^= 0x2000;
 145                         dn_ack(sk, skb, ack);
 146                 }
 147         }
 148
 149         if (skb->len < 2)
 150                 return len;
 151
 152         if ((ack = le16_to_cpu(*ptr)) & 0x8000) {
 153                 skb_pull(skb, 2);
 154                 len += 2;
 155                 if ((ack & 0x4000) == 0) {
 156                         if (oth)
 157                                 ack ^= 0x2000;
 158                         dn_ack(sk, skb, ack);
 159                 }
 160         }
 161
 162         return len;
 163 }
 164
 165
 166 /**
 167  * dn_check_idf - Check an image data field format is correct.
 168  * @pptr: Pointer to pointer to image data
 169  * @len: Pointer to length of image data
 170  * @max: The maximum allowed length of the data in the image data field
 171  * @follow_on: Check that this many bytes exist beyond the end of the image data
 172  *
 173  * Returns: 0 if ok, -1 on error
 174  */
 175 static inline int dn_check_idf(unsigned char **pptr, int *len, unsigned char max, unsigned char follow_on)
 176 {
 177         unsigned char *ptr = *pptr;
 178         unsigned char flen = *ptr++;
 179
 180         (*len)--;
 181         if (flen > max)
 182                 return -1;
 183         if ((flen + follow_on) > *len)
 184                 return -1;
 185
 186         *len -= flen;
 187         *pptr = ptr + flen;
 188         return 0;
 189 }
 190
 191 /*
 192  * Table of reason codes to pass back to node which sent us a badly
 193  * formed message, plus text messages for the log. A zero entry in
 194  * the reason field means "don't reply" otherwise a disc init is sent with
 195  * the specified reason code.
 196  */
 197 static struct {
 198         unsigned short reason;
 199         const char *text;
 200 } ci_err_table[] = {
 201  { 0,             "CI: Truncated message" },
 202  { NSP_REASON_ID, "CI: Destination username error" },
 203  { NSP_REASON_ID, "CI: Destination username type" },
 204  { NSP_REASON_US, "CI: Source username error" },
 205  { 0,             "CI: Truncated at menuver" },
 206  { 0,             "CI: Truncated before access or user data" },
 207  { NSP_REASON_IO, "CI: Access data format error" },
 208  { NSP_REASON_IO, "CI: User data format error" }
 209 };
 210
 211 /*
 212  * This function uses a slightly different lookup method
 213  * to find its sockets, since it searches on object name/number
 214  * rather than port numbers. Various tests are done to ensure that
 215  * the incoming data is in the correct format before it is queued to
 216  * a socket.
 217  */
 218 static struct sock *dn_find_listener(struct sk_buff *skb, unsigned short *reason)
 219 {
 220         struct dn_skb_cb *cb = DN_SKB_CB(skb);
 221         struct nsp_conn_init_msg *msg = (struct nsp_conn_init_msg *)skb->data;
 222         struct sockaddr_dn dstaddr;
 223         struct sockaddr_dn srcaddr;
 224         unsigned char type = 0;
 225         int dstlen;
 226         int srclen;
 227         unsigned char *ptr;
 228         int len;
 229         int err = 0;
 230         unsigned char menuver;
 231
 232         memset(&dstaddr, 0, sizeof(struct sockaddr_dn));
 233         memset(&srcaddr, 0, sizeof(struct sockaddr_dn));
 234
 235         /*
 236          * 1. Decode & remove message header
 237          */
 238         cb->src_port = msg->srcaddr;
 239         cb->dst_port = msg->dstaddr;
 240         cb->services = msg->services;
 241         cb->info     = msg->info;
 242         cb->segsize  = le16_to_cpu(msg->segsize);
 243
 244         if (!pskb_may_pull(skb, sizeof(*msg)))
 245                 goto err_out;
 246
 247         skb_pull(skb, sizeof(*msg));
 248
 249         len = skb->len;
 250         ptr = skb->data;
 251
 252         /*
 253          * 2. Check destination end username format
 254          */
 255         dstlen = dn_username2sockaddr(ptr, len, &dstaddr, &type);
 256         err++;
 257         if (dstlen < 0)
 258                 goto err_out;
 259
 260         err++;
 261         if (type > 1)
 262                 goto err_out;
 263
 264         len -= dstlen;
 265         ptr += dstlen;
 266
 267         /*
 268          * 3. Check source end username format
 269          */
 270         srclen = dn_username2sockaddr(ptr, len, &srcaddr, &type);
 271         err++;
 272         if (srclen < 0)
 273                 goto err_out;
 274
 275         len -= srclen;
 276         ptr += srclen;
 277         err++;
 278         if (len < 1)
 279                 goto err_out;
 280
 281         menuver = *ptr;
 282         ptr++;
 283         len--;
 284
 285         /*
 286          * 4. Check that optional data actually exists if menuver says it does
 287          */
 288         err++;
 289         if ((menuver & (DN_MENUVER_ACC | DN_MENUVER_USR)) && (len < 1))
 290                 goto err_out;
 291
 292         /*
 293          * 5. Check optional access data format
 294          */
 295         err++;
 296         if (menuver & DN_MENUVER_ACC) {
 297                 if (dn_check_idf(&ptr, &len, 39, 1))
 298                         goto err_out;
 299                 if (dn_check_idf(&ptr, &len, 39, 1))
 300                         goto err_out;
 301                 if (dn_check_idf(&ptr, &len, 39, (menuver & DN_MENUVER_USR) ? 1 : 0))
 302                         goto err_out;
 303         }
 304
 305         /*
 306          * 6. Check optional user data format
 307          */
 308         err++;
 309         if (menuver & DN_MENUVER_USR) {
 310                 if (dn_check_idf(&ptr, &len, 16, 0))
 311                         goto err_out;
 312         }
 313
 314         /*
 315          * 7. Look up socket based on destination end username
 316          */
 317         return dn_sklist_find_listener(&dstaddr);
 318 err_out:
 319         dn_log_martian(skb, ci_err_table[err].text);
 320         *reason = ci_err_table[err].reason;
 321         return NULL;
 322 }
 323
 324
 325 static void dn_nsp_conn_init(struct sock *sk, struct sk_buff *skb)
 326 {
 327         if (sk_acceptq_is_full(sk)) {
 328                 kfree_skb(skb);
 329                 return;
 330         }
 331
 332         sk_acceptq_added(sk);
 333         skb_queue_tail(&sk->sk_receive_queue, skb);
 334         sk->sk_state_change(sk);
 335 }
 336
 337 static void dn_nsp_conn_conf(struct sock *sk, struct sk_buff *skb)
 338 {
 339         struct dn_skb_cb *cb = DN_SKB_CB(skb);
 340         struct dn_scp *scp = DN_SK(sk);
 341         unsigned char *ptr;
 342
 343         if (skb->len < 4)
 344                 goto out;
 345
 346         ptr = skb->data;
 347         cb->services = *ptr++;
 348         cb->info = *ptr++;
 349         cb->segsize = le16_to_cpu(*(__le16 *)ptr);
 350
 351         if ((scp->state == DN_CI) || (scp->state == DN_CD)) {
 352                 scp->persist = 0;
 353                 scp->addrrem = cb->src_port;
 354                 sk->sk_state = TCP_ESTABLISHED;
 355                 scp->state = DN_RUN;
 356                 scp->services_rem = cb->services;
 357                 scp->info_rem = cb->info;
 358                 scp->segsize_rem = cb->segsize;
 359
 360                 if ((scp->services_rem & NSP_FC_MASK) == NSP_FC_NONE)
 361                         scp->max_window = decnet_no_fc_max_cwnd;
 362
 363                 if (skb->len > 0) {
 364                         u16 dlen = *skb->data;
 365                         if ((dlen <= 16) && (dlen <= skb->len)) {
 366                                 scp->conndata_in.opt_optl = cpu_to_le16(dlen);
 367                                 skb_copy_from_linear_data_offset(skb, 1,
 368                                               scp->conndata_in.opt_data, dlen);
 369                         }
 370                 }
 371                 dn_nsp_send_link(sk, DN_NOCHANGE, 0);
 372                 if (!sock_flag(sk, SOCK_DEAD))
 373                         sk->sk_state_change(sk);
 374         }
 375
 376 out:
 377         kfree_skb(skb);
 378 }
 379
 380 static void dn_nsp_conn_ack(struct sock *sk, struct sk_buff *skb)
 381 {
 382         struct dn_scp *scp = DN_SK(sk);
 383
 384         if (scp->state == DN_CI) {
 385                 scp->state = DN_CD;
 386                 scp->persist = 0;
 387         }
 388
 389         kfree_skb(skb);
 390 }
 391
 392 static void dn_nsp_disc_init(struct sock *sk, struct sk_buff *skb)
 393 {
 394         struct dn_scp *scp = DN_SK(sk);
 395         struct dn_skb_cb *cb = DN_SKB_CB(skb);
 396         unsigned short reason;
 397
 398         if (skb->len < 2)
 399                 goto out;
 400
 401         reason = le16_to_cpu(*(__le16 *)skb->data);
 402         skb_pull(skb, 2);
 403
 404         scp->discdata_in.opt_status = cpu_to_le16(reason);
 405         scp->discdata_in.opt_optl   = 0;
 406         memset(scp->discdata_in.opt_data, 0, 16);
 407
 408         if (skb->len > 0) {
 409                 u16 dlen = *skb->data;
 410                 if ((dlen <= 16) && (dlen <= skb->len)) {
 411                         scp->discdata_in.opt_optl = cpu_to_le16(dlen);
 412                         skb_copy_from_linear_data_offset(skb, 1, scp->discdata_in.opt_data, dlen);
 413                 }
 414         }
 415
 416         scp->addrrem = cb->src_port;
 417         sk->sk_state = TCP_CLOSE;
 418
 419         switch (scp->state) {
 420         case DN_CI:
 421         case DN_CD:
 422                 scp->state = DN_RJ;
 423                 sk->sk_err = ECONNREFUSED;
 424                 break;
 425         case DN_RUN:
 426                 sk->sk_shutdown |= SHUTDOWN_MASK;
 427                 scp->state = DN_DN;
 428                 break;
 429         case DN_DI:
 430                 scp->state = DN_DIC;
 431                 break;
 432         }
 433
 434         if (!sock_flag(sk, SOCK_DEAD)) {
 435                 if (sk->sk_socket->state != SS_UNCONNECTED)
 436                         sk->sk_socket->state = SS_DISCONNECTING;
 437                 sk->sk_state_change(sk);
 438         }
 439
 440         /*
 441          * It appears that its possible for remote machines to send disc
 442          * init messages with no port identifier if we are in the CI and
 443          * possibly also the CD state. Obviously we shouldn't reply with
 444          * a message if we don't know what the end point is.
 445          */
 446         if (scp->addrrem) {
 447                 dn_nsp_send_disc(sk, NSP_DISCCONF, NSP_REASON_DC, GFP_ATOMIC);
 448         }
 449         scp->persist_fxn = dn_destroy_timer;
 450         scp->persist = dn_nsp_persist(sk);
 451
 452 out:
 453         kfree_skb(skb);
 454 }
 455
 456 /*
 457  * disc_conf messages are also called no_resources or no_link
 458  * messages depending upon the "reason" field.
 459  */
 460 static void dn_nsp_disc_conf(struct sock *sk, struct sk_buff *skb)
 461 {
 462         struct dn_scp *scp = DN_SK(sk);
 463         unsigned short reason;
 464
 465         if (skb->len != 2)
 466                 goto out;
 467
 468         reason = le16_to_cpu(*(__le16 *)skb->data);
 469
 470         sk->sk_state = TCP_CLOSE;
 471
 472         switch (scp->state) {
 473         case DN_CI:
 474                 scp->state = DN_NR;
 475                 break;
 476         case DN_DR:
 477                 if (reason == NSP_REASON_DC)
 478                         scp->state = DN_DRC;
 479                 if (reason == NSP_REASON_NL)
 480                         scp->state = DN_CN;
 481                 break;
 482         case DN_DI:
 483                 scp->state = DN_DIC;
 484                 break;
 485         case DN_RUN:
 486                 sk->sk_shutdown |= SHUTDOWN_MASK;
 487                 fallthrough;
 488         case DN_CC:
 489                 scp->state = DN_CN;
 490         }
 491
 492         if (!sock_flag(sk, SOCK_DEAD)) {
 493                 if (sk->sk_socket->state != SS_UNCONNECTED)
 494                         sk->sk_socket->state = SS_DISCONNECTING;
 495                 sk->sk_state_change(sk);
 496         }
 497
 498         scp->persist_fxn = dn_destroy_timer;
 499         scp->persist = dn_nsp_persist(sk);
 500
 501 out:
 502         kfree_skb(skb);
 503 }
 504
 505 static void dn_nsp_linkservice(struct sock *sk, struct sk_buff *skb)
 506 {
 507         struct dn_scp *scp = DN_SK(sk);
 508         unsigned short segnum;
 509         unsigned char lsflags;
 510         signed char fcval;
 511         int wake_up = 0;
 512         char *ptr = skb->data;
 513         unsigned char fctype = scp->services_rem & NSP_FC_MASK;
 514
 515         if (skb->len != 4)
 516                 goto out;
 517
 518         segnum = le16_to_cpu(*(__le16 *)ptr);
 519         ptr += 2;
 520         lsflags = *(unsigned char *)ptr++;
 521         fcval = *ptr;
 522
 523         /*
 524          * Here we ignore erroneous packets which should really
 525          * should cause a connection abort. It is not critical
 526          * for now though.
 527          */
 528         if (lsflags & 0xf8)
 529                 goto out;
 530
 531         if (seq_next(scp->numoth_rcv, segnum)) {
 532                 seq_add(&scp->numoth_rcv, 1);
 533                 switch(lsflags & 0x04) { /* FCVAL INT */
 534                 case 0x00: /* Normal Request */
 535                         switch(lsflags & 0x03) { /* FCVAL MOD */
 536                         case 0x00: /* Request count */
 537                                 if (fcval < 0) {
 538                                         unsigned char p_fcval = -fcval;
 539                                         if ((scp->flowrem_dat > p_fcval) &&
 540                                             (fctype == NSP_FC_SCMC)) {
 541                                                 scp->flowrem_dat -= p_fcval;
 542                                         }
 543                                 } else if (fcval > 0) {
 544                                         scp->flowrem_dat += fcval;
 545                                         wake_up = 1;
 546                                 }
 547                                 break;
 548                         case 0x01: /* Stop outgoing data */
 549                                 scp->flowrem_sw = DN_DONTSEND;
 550                                 break;
 551                         case 0x02: /* Ok to start again */
 552                                 scp->flowrem_sw = DN_SEND;
 553                                 dn_nsp_output(sk);
 554                                 wake_up = 1;
 555                         }
 556                         break;
 557                 case 0x04: /* Interrupt Request */
 558                         if (fcval > 0) {
 559                                 scp->flowrem_oth += fcval;
 560                                 wake_up = 1;
 561                         }
 562                         break;
 563                 }
 564                 if (wake_up && !sock_flag(sk, SOCK_DEAD))
 565                         sk->sk_state_change(sk);
 566         }
 567
 568         dn_nsp_send_oth_ack(sk);
 569
 570 out:
 571         kfree_skb(skb);
 572 }
 573
 574 /*
 575  * Copy of sock_queue_rcv_skb (from sock.h) without
 576  * bh_lock_sock() (its already held when this is called) which
 577  * also allows data and other data to be queued to a socket.
 578  */
 579 static __inline__ int dn_queue_skb(struct sock *sk, struct sk_buff *skb, int sig, struct sk_buff_head *queue)
 580 {
 581         int err;
 582
 583         /* Cast skb->rcvbuf to unsigned... It's pointless, but reduces
 584            number of warnings when compiling with -W --ANK
 585          */
 586         if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
 587             (unsigned int)sk->sk_rcvbuf) {
 588                 err = -ENOMEM;
 589                 goto out;
 590         }
 591
 592         err = sk_filter(sk, skb);
 593         if (err)
 594                 goto out;
 595
 596         skb_set_owner_r(skb, sk);
 597         skb_queue_tail(queue, skb);
 598
 599         if (!sock_flag(sk, SOCK_DEAD))
 600                 sk->sk_data_ready(sk);
 601 out:
 602         return err;
 603 }
 604
 605 static void dn_nsp_otherdata(struct sock *sk, struct sk_buff *skb)
 606 {
 607         struct dn_scp *scp = DN_SK(sk);
 608         unsigned short segnum;
 609         struct dn_skb_cb *cb = DN_SKB_CB(skb);
 610         int queued = 0;
 611
 612         if (skb->len < 2)
 613                 goto out;
 614
 615         cb->segnum = segnum = le16_to_cpu(*(__le16 *)skb->data);
 616         skb_pull(skb, 2);
 617
 618         if (seq_next(scp->numoth_rcv, segnum)) {
 619
 620                 if (dn_queue_skb(sk, skb, SIGURG, &scp->other_receive_queue) == 0) {
 621                         seq_add(&scp->numoth_rcv, 1);
 622                         scp->other_report = 0;
 623                         queued = 1;
 624                 }
 625         }
 626
 627         dn_nsp_send_oth_ack(sk);
 628 out:
 629         if (!queued)
 630                 kfree_skb(skb);
 631 }
 632
 633 static void dn_nsp_data(struct sock *sk, struct sk_buff *skb)
 634 {
 635         int queued = 0;
 636         unsigned short segnum;
 637         struct dn_skb_cb *cb = DN_SKB_CB(skb);
 638         struct dn_scp *scp = DN_SK(sk);
 639
 640         if (skb->len < 2)
 641                 goto out;
 642
 643         cb->segnum = segnum = le16_to_cpu(*(__le16 *)skb->data);
 644         skb_pull(skb, 2);
 645
 646         if (seq_next(scp->numdat_rcv, segnum)) {
 647                 if (dn_queue_skb(sk, skb, SIGIO, &sk->sk_receive_queue) == 0) {
 648                         seq_add(&scp->numdat_rcv, 1);
 649                         queued = 1;
 650                 }
 651
 652                 if ((scp->flowloc_sw == DN_SEND) && dn_congested(sk)) {
 653                         scp->flowloc_sw = DN_DONTSEND;
 654                         dn_nsp_send_link(sk, DN_DONTSEND, 0);
 655                 }
 656         }
 657
 658         dn_nsp_send_data_ack(sk);
 659 out:
 660         if (!queued)
 661                 kfree_skb(skb);
 662 }
 663
 664 /*
 665  * If one of our conninit messages is returned, this function
 666  * deals with it. It puts the socket into the NO_COMMUNICATION
 667  * state.
 668  */
 669 static void dn_returned_conn_init(struct sock *sk, struct sk_buff *skb)
 670 {
 671         struct dn_scp *scp = DN_SK(sk);
 672
 673         if (scp->state == DN_CI) {
 674                 scp->state = DN_NC;
 675                 sk->sk_state = TCP_CLOSE;
 676                 if (!sock_flag(sk, SOCK_DEAD))
 677                         sk->sk_state_change(sk);
 678         }
 679
 680         kfree_skb(skb);
 681 }
 682
 683 static int dn_nsp_no_socket(struct sk_buff *skb, unsigned short reason)
 684 {
 685         struct dn_skb_cb *cb = DN_SKB_CB(skb);
 686         int ret = NET_RX_DROP;
 687
 688         /* Must not reply to returned packets */
 689         if (cb->rt_flags & DN_RT_F_RTS)
 690                 goto out;
 691
 692         if ((reason != NSP_REASON_OK) && ((cb->nsp_flags & 0x0c) == 0x08)) {
 693                 switch (cb->nsp_flags & 0x70) {
 694                 case 0x10:
 695                 case 0x60: /* (Retransmitted) Connect Init */
 696                         dn_nsp_return_disc(skb, NSP_DISCINIT, reason);
 697                         ret = NET_RX_SUCCESS;
 698                         break;
 699                 case 0x20: /* Connect Confirm */
 700                         dn_nsp_return_disc(skb, NSP_DISCCONF, reason);
 701                         ret = NET_RX_SUCCESS;
 702                         break;
 703                 }
 704         }
 705
 706 out:
 707         kfree_skb(skb);
 708         return ret;
 709 }
 710
 711 static int dn_nsp_rx_packet(struct net *net, struct sock *sk2,
 712                             struct sk_buff *skb)
 713 {
 714         struct dn_skb_cb *cb = DN_SKB_CB(skb);
 715         struct sock *sk = NULL;
 716         unsigned char *ptr = (unsigned char *)skb->data;
 717         unsigned short reason = NSP_REASON_NL;
 718
 719         if (!pskb_may_pull(skb, 2))
 720                 goto free_out;
 721
 722         skb_reset_transport_header(skb);
 723         cb->nsp_flags = *ptr++;
 724
 725         if (decnet_debug_level & 2)
 726                 printk(KERN_DEBUG "dn_nsp_rx: Message type 0x%02x\n", (int)cb->nsp_flags);
 727
 728         if (cb->nsp_flags & 0x83)
 729                 goto free_out;
 730
 731         /*
 732          * Filter out conninits and useless packet types
 733          */
 734         if ((cb->nsp_flags & 0x0c) == 0x08) {
 735                 switch (cb->nsp_flags & 0x70) {
 736                 case 0x00: /* NOP */
 737                 case 0x70: /* Reserved */
 738                 case 0x50: /* Reserved, Phase II node init */
 739                         goto free_out;
 740                 case 0x10:
 741                 case 0x60:
 742                         if (unlikely(cb->rt_flags & DN_RT_F_RTS))
 743                                 goto free_out;
 744                         sk = dn_find_listener(skb, &reason);
 745                         goto got_it;
 746                 }
 747         }
 748
 749         if (!pskb_may_pull(skb, 3))
 750                 goto free_out;
 751
 752         /*
 753          * Grab the destination address.
 754          */
 755         cb->dst_port = *(__le16 *)ptr;
 756         cb->src_port = 0;
 757         ptr += 2;
 758
 759         /*
 760          * If not a connack, grab the source address too.
 761          */
 762         if (pskb_may_pull(skb, 5)) {
 763                 cb->src_port = *(__le16 *)ptr;
 764                 ptr += 2;
 765                 skb_pull(skb, 5);
 766         }
 767
 768         /*
 769          * Returned packets...
 770          * Swap src & dst and look up in the normal way.
 771          */
 772         if (unlikely(cb->rt_flags & DN_RT_F_RTS)) {
 773                 swap(cb->dst_port, cb->src_port);
 774                 swap(cb->dst, cb->src);
 775         }
 776
 777         /*
 778          * Find the socket to which this skb is destined.
 779          */
 780         sk = dn_find_by_skb(skb);
 781 got_it:
 782         if (sk != NULL) {
 783                 struct dn_scp *scp = DN_SK(sk);
 784
 785                 /* Reset backoff */
 786                 scp->nsp_rxtshift = 0;
 787
 788                 /*
 789                  * We linearize everything except data segments here.
 790                  */
 791                 if (cb->nsp_flags & ~0x60) {
 792                         if (unlikely(skb_linearize(skb)))
 793                                 goto free_out;
 794                 }
 795
 796                 return sk_receive_skb(sk, skb, 0);
 797         }
 798
 799         return dn_nsp_no_socket(skb, reason);
 800
 801 free_out:
 802         kfree_skb(skb);
 803         return NET_RX_DROP;
 804 }
 805
 806 int dn_nsp_rx(struct sk_buff *skb)
 807 {
 808         return NF_HOOK(NFPROTO_DECNET, NF_DN_LOCAL_IN,
 809                        &init_net, NULL, skb, skb->dev, NULL,
 810                        dn_nsp_rx_packet);
 811 }
 812
 813 /*
 814  * This is the main receive routine for sockets. It is called
 815  * from the above when the socket is not busy, and also from
 816  * sock_release() when there is a backlog queued up.
 817  */
 818 int dn_nsp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 819 {
 820         struct dn_scp *scp = DN_SK(sk);
 821         struct dn_skb_cb *cb = DN_SKB_CB(skb);
 822
 823         if (cb->rt_flags & DN_RT_F_RTS) {
 824                 if (cb->nsp_flags == 0x18 || cb->nsp_flags == 0x68)
 825                         dn_returned_conn_init(sk, skb);
 826                 else
 827                         kfree_skb(skb);
 828                 return NET_RX_SUCCESS;
 829         }
 830
 831         /*
 832          * Control packet.
 833          */
 834         if ((cb->nsp_flags & 0x0c) == 0x08) {
 835                 switch (cb->nsp_flags & 0x70) {
 836                 case 0x10:
 837                 case 0x60:
 838                         dn_nsp_conn_init(sk, skb);
 839                         break;
 840                 case 0x20:
 841                         dn_nsp_conn_conf(sk, skb);
 842                         break;
 843                 case 0x30:
 844                         dn_nsp_disc_init(sk, skb);
 845                         break;
 846                 case 0x40:
 847                         dn_nsp_disc_conf(sk, skb);
 848                         break;
 849                 }
 850
 851         } else if (cb->nsp_flags == 0x24) {
 852                 /*
 853                  * Special for connacks, 'cos they don't have
 854                  * ack data or ack otherdata info.
 855                  */
 856                 dn_nsp_conn_ack(sk, skb);
 857         } else {
 858                 int other = 1;
 859
 860                 /* both data and ack frames can kick a CC socket into RUN */
 861                 if ((scp->state == DN_CC) && !sock_flag(sk, SOCK_DEAD)) {
 862                         scp->state = DN_RUN;
 863                         sk->sk_state = TCP_ESTABLISHED;
 864                         sk->sk_state_change(sk);
 865                 }
 866
 867                 if ((cb->nsp_flags & 0x1c) == 0)
 868                         other = 0;
 869                 if (cb->nsp_flags == 0x04)
 870                         other = 0;
 871
 872                 /*
 873                  * Read out ack data here, this applies equally
 874                  * to data, other data, link service and both
 875                  * ack data and ack otherdata.
 876                  */
 877                 dn_process_ack(sk, skb, other);
 878
 879                 /*
 880                  * If we've some sort of data here then call a
 881                  * suitable routine for dealing with it, otherwise
 882                  * the packet is an ack and can be discarded.
 883                  */
 884                 if ((cb->nsp_flags & 0x0c) == 0) {
 885
 886                         if (scp->state != DN_RUN)
 887                                 goto free_out;
 888
 889                         switch (cb->nsp_flags) {
 890                         case 0x10: /* LS */
 891                                 dn_nsp_linkservice(sk, skb);
 892                                 break;
 893                         case 0x30: /* OD */
 894                                 dn_nsp_otherdata(sk, skb);
 895                                 break;
 896                         default:
 897                                 dn_nsp_data(sk, skb);
 898                         }
 899
 900                 } else { /* Ack, chuck it out here */
 901 free_out:
 902                         kfree_skb(skb);
 903                 }
 904         }
 905
 906         return NET_RX_SUCCESS;
 907 }