net/ax25/ax25_in.c

   1 /*
   2  * This program is free software; you can redistribute it and/or modify
   3  * it under the terms of the GNU General Public License as published by
   4  * the Free Software Foundation; either version 2 of the License, or
   5  * (at your option) any later version.
   6  *
   7  * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
   8  * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   9  * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
  10  * Copyright (C) Hans-Joachim Hetscher DD8NE (dd8ne@bnv-bamberg.de)
  11  */
  12 #include <linux/config.h>
  13 #include <linux/errno.h>
  14 #include <linux/types.h>
  15 #include <linux/socket.h>
  16 #include <linux/in.h>
  17 #include <linux/kernel.h>
  18 #include <linux/sched.h>
  19 #include <linux/timer.h>
  20 #include <linux/string.h>
  21 #include <linux/sockios.h>
  22 #include <linux/net.h>
  23 #include <net/ax25.h>
  24 #include <linux/inet.h>
  25 #include <linux/netdevice.h>
  26 #include <linux/skbuff.h>
  27 #include <linux/netfilter.h>
  28 #include <net/sock.h>
  29 #include <net/ip.h>                     /* For ip_rcv */
  30 #include <net/tcp.h>
  31 #include <net/arp.h>                    /* For arp_rcv */
  32 #include <asm/uaccess.h>
  33 #include <asm/system.h>
  34 #include <linux/fcntl.h>
  35 #include <linux/mm.h>
  36 #include <linux/interrupt.h>
  37
  38 /*
  39  *      Given a fragment, queue it on the fragment queue and if the fragment
  40  *      is complete, send it back to ax25_rx_iframe.
  41  */
  42 static int ax25_rx_fragment(ax25_cb *ax25, struct sk_buff *skb)
  43 {
  44         struct sk_buff *skbn, *skbo;
  45
  46         if (ax25->fragno != 0) {
  47                 if (!(*skb->data & AX25_SEG_FIRST)) {
  48                         if ((ax25->fragno - 1) == (*skb->data & AX25_SEG_REM)) {
  49                                 /* Enqueue fragment */
  50                                 ax25->fragno = *skb->data & AX25_SEG_REM;
  51                                 skb_pull(skb, 1);       /* skip fragno */
  52                                 ax25->fraglen += skb->len;
  53                                 skb_queue_tail(&ax25->frag_queue, skb);
  54
  55                                 /* Last fragment received ? */
  56                                 if (ax25->fragno == 0) {
  57                                         skbn = alloc_skb(AX25_MAX_HEADER_LEN +
  58                                                          ax25->fraglen,
  59                                                          GFP_ATOMIC);
  60                                         if (!skbn) {
  61                                                 skb_queue_purge(&ax25->frag_queue);
  62                                                 return 1;
  63                                         }
  64
  65                                         skb_reserve(skbn, AX25_MAX_HEADER_LEN);
  66
  67                                         skbn->dev   = ax25->ax25_dev->dev;
  68                                         skbn->h.raw = skbn->data;
  69                                         skbn->nh.raw = skbn->data;
  70
  71                                         /* Copy data from the fragments */
  72                                         while ((skbo = skb_dequeue(&ax25->frag_queue)) != NULL) {
  73                                                 memcpy(skb_put(skbn, skbo->len), skbo->data, skbo->len);
  74                                                 kfree_skb(skbo);
  75                                         }
  76
  77                                         ax25->fraglen = 0;
  78
  79                                         if (ax25_rx_iframe(ax25, skbn) == 0)
  80                                                 kfree_skb(skbn);
  81                                 }
  82
  83                                 return 1;
  84                         }
  85                 }
  86         } else {
  87                 /* First fragment received */
  88                 if (*skb->data & AX25_SEG_FIRST) {
  89                         skb_queue_purge(&ax25->frag_queue);
  90                         ax25->fragno = *skb->data & AX25_SEG_REM;
  91                         skb_pull(skb, 1);               /* skip fragno */
  92                         ax25->fraglen = skb->len;
  93                         skb_queue_tail(&ax25->frag_queue, skb);
  94                         return 1;
  95                 }
  96         }
  97
  98         return 0;
  99 }
 100
 101 /*
 102  *      This is where all valid I frames are sent to, to be dispatched to
 103  *      whichever protocol requires them.
 104  */
 105 int ax25_rx_iframe(ax25_cb *ax25, struct sk_buff *skb)
 106 {
 107         int (*func)(struct sk_buff *, ax25_cb *);
 108         volatile int queued = 0;
 109         unsigned char pid;
 110
 111         if (skb == NULL) return 0;
 112
 113         ax25_start_idletimer(ax25);
 114
 115         pid = *skb->data;
 116
 117 #ifdef CONFIG_INET
 118         if (pid == AX25_P_IP) {
 119                 /* working around a TCP bug to keep additional listeners
 120                  * happy. TCP re-uses the buffer and destroys the original
 121                  * content.
 122                  */
 123                 struct sk_buff *skbn = skb_copy(skb, GFP_ATOMIC);
 124                 if (skbn != NULL) {
 125                         kfree_skb(skb);
 126                         skb = skbn;
 127                 }
 128
 129                 skb_pull(skb, 1);       /* Remove PID */
 130                 skb->h.raw    = skb->data;
 131                 skb->nh.raw   = skb->data;
 132                 skb->dev      = ax25->ax25_dev->dev;
 133                 skb->pkt_type = PACKET_HOST;
 134                 skb->protocol = htons(ETH_P_IP);
 135                 ip_rcv(skb, skb->dev, NULL);    /* Wrong ptype */
 136                 return 1;
 137         }
 138 #endif
 139         if (pid == AX25_P_SEGMENT) {
 140                 skb_pull(skb, 1);       /* Remove PID */
 141                 return ax25_rx_fragment(ax25, skb);
 142         }
 143
 144         if ((func = ax25_protocol_function(pid)) != NULL) {
 145                 skb_pull(skb, 1);       /* Remove PID */
 146                 return (*func)(skb, ax25);
 147         }
 148
 149         if (ax25->sk != NULL && ax25->ax25_dev->values[AX25_VALUES_CONMODE] == 2) {
 150                 if ((!ax25->pidincl && ax25->sk->sk_protocol == pid) ||
 151                     ax25->pidincl) {
 152                         if (sock_queue_rcv_skb(ax25->sk, skb) == 0)
 153                                 queued = 1;
 154                         else
 155                                 ax25->condition |= AX25_COND_OWN_RX_BUSY;
 156                 }
 157         }
 158
 159         return queued;
 160 }
 161
 162 /*
 163  *      Higher level upcall for a LAPB frame
 164  */
 165 static int ax25_process_rx_frame(ax25_cb *ax25, struct sk_buff *skb, int type, int dama)
 166 {
 167         int queued = 0;
 168
 169         if (ax25->state == AX25_STATE_0)
 170                 return 0;
 171
 172         switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 173         case AX25_PROTO_STD_SIMPLEX:
 174         case AX25_PROTO_STD_DUPLEX:
 175                 queued = ax25_std_frame_in(ax25, skb, type);
 176                 break;
 177
 178 #ifdef CONFIG_AX25_DAMA_SLAVE
 179         case AX25_PROTO_DAMA_SLAVE:
 180                 if (dama || ax25->ax25_dev->dama.slave)
 181                         queued = ax25_ds_frame_in(ax25, skb, type);
 182                 else
 183                         queued = ax25_std_frame_in(ax25, skb, type);
 184                 break;
 185 #endif
 186         }
 187
 188         return queued;
 189 }
 190
 191 static int ax25_rcv(struct sk_buff *skb, struct net_device *dev,
 192         ax25_address *dev_addr, struct packet_type *ptype)
 193 {
 194         ax25_address src, dest, *next_digi = NULL;
 195         int type = 0, mine = 0, dama;
 196         struct sock *make, *sk;
 197         ax25_digi dp, reverse_dp;
 198         ax25_cb *ax25;
 199         ax25_dev *ax25_dev;
 200
 201         /*
 202          *      Process the AX.25/LAPB frame.
 203          */
 204
 205         skb->h.raw = skb->data;
 206
 207         if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) {
 208                 kfree_skb(skb);
 209                 return 0;
 210         }
 211
 212         /*
 213          *      Parse the address header.
 214          */
 215
 216         if (ax25_addr_parse(skb->data, skb->len, &src, &dest, &dp, &type, &dama) == NULL) {
 217                 kfree_skb(skb);
 218                 return 0;
 219         }
 220
 221         /*
 222          *      Ours perhaps ?
 223          */
 224         if (dp.lastrepeat + 1 < dp.ndigi)               /* Not yet digipeated completely */
 225                 next_digi = &dp.calls[dp.lastrepeat + 1];
 226
 227         /*
 228          *      Pull of the AX.25 headers leaving the CTRL/PID bytes
 229          */
 230         skb_pull(skb, ax25_addr_size(&dp));
 231
 232         /* For our port addresses ? */
 233         if (ax25cmp(&dest, dev_addr) == 0 && dp.lastrepeat + 1 == dp.ndigi)
 234                 mine = 1;
 235
 236         /* Also match on any registered callsign from L3/4 */
 237         if (!mine && ax25_listen_mine(&dest, dev) && dp.lastrepeat + 1 == dp.ndigi)
 238                 mine = 1;
 239
 240         /* UI frame - bypass LAPB processing */
 241         if ((*skb->data & ~0x10) == AX25_UI && dp.lastrepeat + 1 == dp.ndigi) {
 242                 skb->h.raw = skb->data + 2;             /* skip control and pid */
 243
 244                 ax25_send_to_raw(&dest, skb, skb->data[1]);
 245
 246                 if (!mine && ax25cmp(&dest, (ax25_address *)dev->broadcast) != 0) {
 247                         kfree_skb(skb);
 248                         return 0;
 249                 }
 250
 251                 /* Now we are pointing at the pid byte */
 252                 switch (skb->data[1]) {
 253 #ifdef CONFIG_INET
 254                 case AX25_P_IP:
 255                         skb_pull(skb,2);                /* drop PID/CTRL */
 256                         skb->h.raw    = skb->data;
 257                         skb->nh.raw   = skb->data;
 258                         skb->dev      = dev;
 259                         skb->pkt_type = PACKET_HOST;
 260                         skb->protocol = htons(ETH_P_IP);
 261                         ip_rcv(skb, dev, ptype);        /* Note ptype here is the wrong one, fix me later */
 262                         break;
 263
 264                 case AX25_P_ARP:
 265                         skb_pull(skb,2);
 266                         skb->h.raw    = skb->data;
 267                         skb->nh.raw   = skb->data;
 268                         skb->dev      = dev;
 269                         skb->pkt_type = PACKET_HOST;
 270                         skb->protocol = htons(ETH_P_ARP);
 271                         arp_rcv(skb, dev, ptype);       /* Note ptype here is wrong... */
 272                         break;
 273 #endif
 274                 case AX25_P_TEXT:
 275                         /* Now find a suitable dgram socket */
 276                         sk = ax25_get_socket(&dest, &src, SOCK_DGRAM);
 277                         if (sk != NULL) {
 278                                 bh_lock_sock(sk);
 279                                 if (atomic_read(&sk->sk_rmem_alloc) >=
 280                                     sk->sk_rcvbuf) {
 281                                         kfree_skb(skb);
 282                                 } else {
 283                                         /*
 284                                          *      Remove the control and PID.
 285                                          */
 286                                         skb_pull(skb, 2);
 287                                         if (sock_queue_rcv_skb(sk, skb) != 0)
 288                                                 kfree_skb(skb);
 289                                 }
 290                                 bh_unlock_sock(sk);
 291                                 sock_put(sk);
 292                         } else {
 293                                 kfree_skb(skb);
 294                         }
 295                         break;
 296
 297                 default:
 298                         kfree_skb(skb); /* Will scan SOCK_AX25 RAW sockets */
 299                         break;
 300                 }
 301
 302                 return 0;
 303         }
 304
 305         /*
 306          *      Is connected mode supported on this device ?
 307          *      If not, should we DM the incoming frame (except DMs) or
 308          *      silently ignore them. For now we stay quiet.
 309          */
 310         if (ax25_dev->values[AX25_VALUES_CONMODE] == 0) {
 311                 kfree_skb(skb);
 312                 return 0;
 313         }
 314
 315         /* LAPB */
 316
 317         /* AX.25 state 1-4 */
 318
 319         ax25_digi_invert(&dp, &reverse_dp);
 320
 321         if ((ax25 = ax25_find_cb(&dest, &src, &reverse_dp, dev)) != NULL) {
 322                 /*
 323                  *      Process the frame. If it is queued up internally it
 324                  *      returns one otherwise we free it immediately. This
 325                  *      routine itself wakes the user context layers so we do
 326                  *      no further work
 327                  */
 328                 if (ax25_process_rx_frame(ax25, skb, type, dama) == 0)
 329                         kfree_skb(skb);
 330
 331                 ax25_cb_put(ax25);
 332                 return 0;
 333         }
 334
 335         /* AX.25 state 0 (disconnected) */
 336
 337         /* a) received not a SABM(E) */
 338
 339         if ((*skb->data & ~AX25_PF) != AX25_SABM &&
 340             (*skb->data & ~AX25_PF) != AX25_SABME) {
 341                 /*
 342                  *      Never reply to a DM. Also ignore any connects for
 343                  *      addresses that are not our interfaces and not a socket.
 344                  */
 345                 if ((*skb->data & ~AX25_PF) != AX25_DM && mine)
 346                         ax25_return_dm(dev, &src, &dest, &dp);
 347
 348                 kfree_skb(skb);
 349                 return 0;
 350         }
 351
 352         /* b) received SABM(E) */
 353
 354         if (dp.lastrepeat + 1 == dp.ndigi)
 355                 sk = ax25_find_listener(&dest, 0, dev, SOCK_SEQPACKET);
 356         else
 357                 sk = ax25_find_listener(next_digi, 1, dev, SOCK_SEQPACKET);
 358
 359         if (sk != NULL) {
 360                 bh_lock_sock(sk);
 361                 if (sk_acceptq_is_full(sk) ||
 362                     (make = ax25_make_new(sk, ax25_dev)) == NULL) {
 363                         if (mine)
 364                                 ax25_return_dm(dev, &src, &dest, &dp);
 365                         kfree_skb(skb);
 366                         bh_unlock_sock(sk);
 367                         sock_put(sk);
 368
 369                         return 0;
 370                 }
 371
 372                 ax25 = ax25_sk(make);
 373                 skb_set_owner_r(skb, make);
 374                 skb_queue_head(&sk->sk_receive_queue, skb);
 375
 376                 make->sk_state = TCP_ESTABLISHED;
 377
 378                 sk->sk_ack_backlog++;
 379                 bh_unlock_sock(sk);
 380         } else {
 381                 if (!mine) {
 382                         kfree_skb(skb);
 383                         return 0;
 384                 }
 385
 386                 if ((ax25 = ax25_create_cb()) == NULL) {
 387                         ax25_return_dm(dev, &src, &dest, &dp);
 388                         kfree_skb(skb);
 389                         return 0;
 390                 }
 391
 392                 ax25_fillin_cb(ax25, ax25_dev);
 393         }
 394
 395         ax25->source_addr = dest;
 396         ax25->dest_addr   = src;
 397
 398         /*
 399          *      Sort out any digipeated paths.
 400          */
 401         if (dp.ndigi && !ax25->digipeat &&
 402             (ax25->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
 403                 kfree_skb(skb);
 404                 ax25_destroy_socket(ax25);
 405                 if (sk)
 406                         sock_put(sk);
 407                 return 0;
 408         }
 409
 410         if (dp.ndigi == 0) {
 411                 if (ax25->digipeat != NULL) {
 412                         kfree(ax25->digipeat);
 413                         ax25->digipeat = NULL;
 414                 }
 415         } else {
 416                 /* Reverse the source SABM's path */
 417                 memcpy(ax25->digipeat, &reverse_dp, sizeof(ax25_digi));
 418         }
 419
 420         if ((*skb->data & ~AX25_PF) == AX25_SABME) {
 421                 ax25->modulus = AX25_EMODULUS;
 422                 ax25->window  = ax25_dev->values[AX25_VALUES_EWINDOW];
 423         } else {
 424                 ax25->modulus = AX25_MODULUS;
 425                 ax25->window  = ax25_dev->values[AX25_VALUES_WINDOW];
 426         }
 427
 428         ax25_send_control(ax25, AX25_UA, AX25_POLLON, AX25_RESPONSE);
 429
 430 #ifdef CONFIG_AX25_DAMA_SLAVE
 431         if (dama && ax25->ax25_dev->values[AX25_VALUES_PROTOCOL] == AX25_PROTO_DAMA_SLAVE)
 432                 ax25_dama_on(ax25);
 433 #endif
 434
 435         ax25->state = AX25_STATE_3;
 436
 437         ax25_cb_add(ax25);
 438
 439         ax25_start_heartbeat(ax25);
 440         ax25_start_t3timer(ax25);
 441         ax25_start_idletimer(ax25);
 442
 443         if (sk) {
 444                 if (!sock_flag(sk, SOCK_DEAD))
 445                         sk->sk_data_ready(sk, skb->len);
 446                 sock_put(sk);
 447         } else
 448                 kfree_skb(skb);
 449
 450         return 0;
 451 }
 452
 453 /*
 454  *      Receive an AX.25 frame via a SLIP interface.
 455  */
 456 int ax25_kiss_rcv(struct sk_buff *skb, struct net_device *dev,
 457                   struct packet_type *ptype)
 458 {
 459         skb->sk = NULL;         /* Initially we don't know who it's for */
 460         skb->destructor = NULL; /* Who initializes this, dammit?! */
 461
 462         if ((*skb->data & 0x0F) != 0) {
 463                 kfree_skb(skb); /* Not a KISS data frame */
 464                 return 0;
 465         }
 466
 467         skb_pull(skb, AX25_KISS_HEADER_LEN);    /* Remove the KISS byte */
 468
 469         return ax25_rcv(skb, dev, (ax25_address *)dev->dev_addr, ptype);
 470 }