LXR linux/net/ax25/ax25

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