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 <net/sock.h>
  27#include <net/tcp_states.h>
  28#include <asm/uaccess.h>
  29#include <linux/fcntl.h>
  30#include <linux/mm.h>
  31#include <linux/interrupt.h>
  32
  33/*
  34 *      Given a fragment, queue it on the fragment queue and if the fragment
  35 *      is complete, send it back to ax25_rx_iframe.
  36 */
  37static int ax25_rx_fragment(ax25_cb *ax25, struct sk_buff *skb)
  38{
  39        struct sk_buff *skbn, *skbo;
  40
  41        if (ax25->fragno != 0) {
  42                if (!(*skb->data & AX25_SEG_FIRST)) {
  43                        if ((ax25->fragno - 1) == (*skb->data & AX25_SEG_REM)) {
  44                                /* Enqueue fragment */
  45                                ax25->fragno = *skb->data & AX25_SEG_REM;
  46                                skb_pull(skb, 1);       /* skip fragno */
  47                                ax25->fraglen += skb->len;
  48                                skb_queue_tail(&ax25->frag_queue, skb);
  49
  50                                /* Last fragment received ? */
  51                                if (ax25->fragno == 0) {
  52                                        skbn = alloc_skb(AX25_MAX_HEADER_LEN +
  53                                                         ax25->fraglen,
  54                                                         GFP_ATOMIC);
  55                                        if (!skbn) {
  56                                                skb_queue_purge(&ax25->frag_queue);
  57                                                return 1;
  58                                        }
  59
  60                                        skb_reserve(skbn, AX25_MAX_HEADER_LEN);
  61
  62                                        skbn->dev   = ax25->ax25_dev->dev;
  63                                        skb_reset_network_header(skbn);
  64                                        skb_reset_transport_header(skbn);
  65
  66                                        /* Copy data from the fragments */
  67                                        while ((skbo = skb_dequeue(&ax25->frag_queue)) != NULL) {
  68                                                skb_copy_from_linear_data(skbo,
  69                                                          skb_put(skbn, skbo->len),
  70                                                                          skbo->len);
  71                                                kfree_skb(skbo);
  72                                        }
  73
  74                                        ax25->fraglen = 0;
  75
  76                                        if (ax25_rx_iframe(ax25, skbn) == 0)
  77                                                kfree_skb(skbn);
  78                                }
  79
  80                                return 1;
  81                        }
  82                }
  83        } else {
  84                /* First fragment received */
  85                if (*skb->data & AX25_SEG_FIRST) {
  86                        skb_queue_purge(&ax25->frag_queue);
  87                        ax25->fragno = *skb->data & AX25_SEG_REM;
  88                        skb_pull(skb, 1);               /* skip fragno */
  89                        ax25->fraglen = skb->len;
  90                        skb_queue_tail(&ax25->frag_queue, skb);
  91                        return 1;
  92                }
  93        }
  94
  95        return 0;
  96}
  97
  98/*
  99 *      This is where all valid I frames are sent to, to be dispatched to
 100 *      whichever protocol requires them.
 101 */
 102int ax25_rx_iframe(ax25_cb *ax25, struct sk_buff *skb)
 103{
 104        int (*func)(struct sk_buff *, ax25_cb *);
 105        unsigned char pid;
 106        int queued = 0;
 107
 108        if (skb == NULL) return 0;
 109
 110        ax25_start_idletimer(ax25);
 111
 112        pid = *skb->data;
 113
 114        if (pid == AX25_P_IP) {
 115                /* working around a TCP bug to keep additional listeners
 116                 * happy. TCP re-uses the buffer and destroys the original
 117                 * content.
 118                 */
 119                struct sk_buff *skbn = skb_copy(skb, GFP_ATOMIC);
 120                if (skbn != NULL) {
 121                        kfree_skb(skb);
 122                        skb = skbn;
 123                }
 124
 125                skb_pull(skb, 1);       /* Remove PID */
 126                skb->mac_header = skb->network_header;
 127                skb_reset_network_header(skb);
 128                skb->dev      = ax25->ax25_dev->dev;
 129                skb->pkt_type = PACKET_HOST;
 130                skb->protocol = htons(ETH_P_IP);
 131                netif_rx(skb);
 132                return 1;
 133        }
 134        if (pid == AX25_P_SEGMENT) {
 135                skb_pull(skb, 1);       /* Remove PID */
 136                return ax25_rx_fragment(ax25, skb);
 137        }
 138
 139        if ((func = ax25_protocol_function(pid)) != NULL) {
 140                skb_pull(skb, 1);       /* Remove PID */
 141                return (*func)(skb, ax25);
 142        }
 143
 144        if (ax25->sk != NULL && ax25->ax25_dev->values[AX25_VALUES_CONMODE] == 2) {
 145                if ((!ax25->pidincl && ax25->sk->sk_protocol == pid) ||
 146                    ax25->pidincl) {
 147                        if (sock_queue_rcv_skb(ax25->sk, skb) == 0)
 148                                queued = 1;
 149                        else
 150                                ax25->condition |= AX25_COND_OWN_RX_BUSY;
 151                }
 152        }
 153
 154        return queued;
 155}
 156
 157/*
 158 *      Higher level upcall for a LAPB frame
 159 */
 160static int ax25_process_rx_frame(ax25_cb *ax25, struct sk_buff *skb, int type, int dama)
 161{
 162        int queued = 0;
 163
 164        if (ax25->state == AX25_STATE_0)
 165                return 0;
 166
 167        switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 168        case AX25_PROTO_STD_SIMPLEX:
 169        case AX25_PROTO_STD_DUPLEX:
 170                queued = ax25_std_frame_in(ax25, skb, type);
 171                break;
 172
 173#ifdef CONFIG_AX25_DAMA_SLAVE
 174        case AX25_PROTO_DAMA_SLAVE:
 175                if (dama || ax25->ax25_dev->dama.slave)
 176                        queued = ax25_ds_frame_in(ax25, skb, type);
 177                else
 178                        queued = ax25_std_frame_in(ax25, skb, type);
 179                break;
 180#endif
 181        }
 182
 183        return queued;
 184}
 185
 186static int ax25_rcv(struct sk_buff *skb, struct net_device *dev,
 187        ax25_address *dev_addr, struct packet_type *ptype)
 188{
 189        ax25_address src, dest, *next_digi = NULL;
 190        int type = 0, mine = 0, dama;
 191        struct sock *make, *sk;
 192        ax25_digi dp, reverse_dp;
 193        ax25_cb *ax25;
 194        ax25_dev *ax25_dev;
 195
 196        /*
 197         *      Process the AX.25/LAPB frame.
 198         */
 199
 200        skb_reset_transport_header(skb);
 201
 202        if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
 203                goto free;
 204
 205        /*
 206         *      Parse the address header.
 207         */
 208
 209        if (ax25_addr_parse(skb->data, skb->len, &src, &dest, &dp, &type, &dama) == NULL)
 210                goto free;
 211
 212        /*
 213         *      Ours perhaps ?
 214         */
 215        if (dp.lastrepeat + 1 < dp.ndigi)               /* Not yet digipeated completely */
 216                next_digi = &dp.calls[dp.lastrepeat + 1];
 217
 218        /*
 219         *      Pull of the AX.25 headers leaving the CTRL/PID bytes
 220         */
 221        skb_pull(skb, ax25_addr_size(&dp));
 222
 223        /* For our port addresses ? */
 224        if (ax25cmp(&dest, dev_addr) == 0 && dp.lastrepeat + 1 == dp.ndigi)
 225                mine = 1;
 226
 227        /* Also match on any registered callsign from L3/4 */
 228        if (!mine && ax25_listen_mine(&dest, dev) && dp.lastrepeat + 1 == dp.ndigi)
 229                mine = 1;
 230
 231        /* UI frame - bypass LAPB processing */
 232        if ((*skb->data & ~0x10) == AX25_UI && dp.lastrepeat + 1 == dp.ndigi) {
 233                skb_set_transport_header(skb, 2); /* skip control and pid */
 234
 235                ax25_send_to_raw(&dest, skb, skb->data[1]);
 236
 237                if (!mine && ax25cmp(&dest, (ax25_address *)dev->broadcast) != 0)
 238                        goto free;
 239
 240                /* Now we are pointing at the pid byte */
 241                switch (skb->data[1]) {
 242                case AX25_P_IP:
 243                        skb_pull(skb,2);                /* drop PID/CTRL */
 244                        skb_reset_transport_header(skb);
 245                        skb_reset_network_header(skb);
 246                        skb->dev      = dev;
 247                        skb->pkt_type = PACKET_HOST;
 248                        skb->protocol = htons(ETH_P_IP);
 249                        netif_rx(skb);
 250                        break;
 251
 252                case AX25_P_ARP:
 253                        skb_pull(skb,2);
 254                        skb_reset_transport_header(skb);
 255                        skb_reset_network_header(skb);
 256                        skb->dev      = dev;
 257                        skb->pkt_type = PACKET_HOST;
 258                        skb->protocol = htons(ETH_P_ARP);
 259                        netif_rx(skb);
 260                        break;
 261                case AX25_P_TEXT:
 262                        /* Now find a suitable dgram socket */
 263                        sk = ax25_get_socket(&dest, &src, SOCK_DGRAM);
 264                        if (sk != NULL) {
 265                                bh_lock_sock(sk);
 266                                if (atomic_read(&sk->sk_rmem_alloc) >=
 267                                    sk->sk_rcvbuf) {
 268                                        kfree_skb(skb);
 269                                } else {
 270                                        /*
 271                                         *      Remove the control and PID.
 272                                         */
 273                                        skb_pull(skb, 2);
 274                                        if (sock_queue_rcv_skb(sk, skb) != 0)
 275                                                kfree_skb(skb);
 276                                }
 277                                bh_unlock_sock(sk);
 278                                sock_put(sk);
 279                        } else {
 280                                kfree_skb(skb);
 281                        }
 282                        break;
 283
 284                default:
 285                        kfree_skb(skb); /* Will scan SOCK_AX25 RAW sockets */
 286                        break;
 287                }
 288
 289                return 0;
 290        }
 291
 292        /*
 293         *      Is connected mode supported on this device ?
 294         *      If not, should we DM the incoming frame (except DMs) or
 295         *      silently ignore them. For now we stay quiet.
 296         */
 297        if (ax25_dev->values[AX25_VALUES_CONMODE] == 0)
 298                goto free;
 299
 300        /* LAPB */
 301
 302        /* AX.25 state 1-4 */
 303
 304        ax25_digi_invert(&dp, &reverse_dp);
 305
 306        if ((ax25 = ax25_find_cb(&dest, &src, &reverse_dp, dev)) != NULL) {
 307                /*
 308                 *      Process the frame. If it is queued up internally it
 309                 *      returns one otherwise we free it immediately. This
 310                 *      routine itself wakes the user context layers so we do
 311                 *      no further work
 312                 */
 313                if (ax25_process_rx_frame(ax25, skb, type, dama) == 0)
 314                        kfree_skb(skb);
 315
 316                ax25_cb_put(ax25);
 317                return 0;
 318        }
 319
 320        /* AX.25 state 0 (disconnected) */
 321
 322        /* a) received not a SABM(E) */
 323
 324        if ((*skb->data & ~AX25_PF) != AX25_SABM &&
 325            (*skb->data & ~AX25_PF) != AX25_SABME) {
 326                /*
 327                 *      Never reply to a DM. Also ignore any connects for
 328                 *      addresses that are not our interfaces and not a socket.
 329                 */
 330                if ((*skb->data & ~AX25_PF) != AX25_DM && mine)
 331                        ax25_return_dm(dev, &src, &dest, &dp);
 332
 333                goto free;
 334        }
 335
 336        /* b) received SABM(E) */
 337
 338        if (dp.lastrepeat + 1 == dp.ndigi)
 339                sk = ax25_find_listener(&dest, 0, dev, SOCK_SEQPACKET);
 340        else
 341                sk = ax25_find_listener(next_digi, 1, dev, SOCK_SEQPACKET);
 342
 343        if (sk != NULL) {
 344                bh_lock_sock(sk);
 345                if (sk_acceptq_is_full(sk) ||
 346                    (make = ax25_make_new(sk, ax25_dev)) == NULL) {
 347                        if (mine)
 348                                ax25_return_dm(dev, &src, &dest, &dp);
 349                        kfree_skb(skb);
 350                        bh_unlock_sock(sk);
 351                        sock_put(sk);
 352
 353                        return 0;
 354                }
 355
 356                ax25 = sk_to_ax25(make);
 357                skb_set_owner_r(skb, make);
 358                skb_queue_head(&sk->sk_receive_queue, skb);
 359
 360                make->sk_state = TCP_ESTABLISHED;
 361
 362                sk->sk_ack_backlog++;
 363                bh_unlock_sock(sk);
 364        } else {
 365                if (!mine)
 366                        goto free;
 367
 368                if ((ax25 = ax25_create_cb()) == NULL) {
 369                        ax25_return_dm(dev, &src, &dest, &dp);
 370                        goto free;
 371                }
 372
 373                ax25_fillin_cb(ax25, ax25_dev);
 374        }
 375
 376        ax25->source_addr = dest;
 377        ax25->dest_addr   = src;
 378
 379        /*
 380         *      Sort out any digipeated paths.
 381         */
 382        if (dp.ndigi && !ax25->digipeat &&
 383            (ax25->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
 384                kfree_skb(skb);
 385                ax25_destroy_socket(ax25);
 386                if (sk)
 387                        sock_put(sk);
 388                return 0;
 389        }
 390
 391        if (dp.ndigi == 0) {
 392                kfree(ax25->digipeat);
 393                ax25->digipeat = NULL;
 394        } else {
 395                /* Reverse the source SABM's path */
 396                memcpy(ax25->digipeat, &reverse_dp, sizeof(ax25_digi));
 397        }
 398
 399        if ((*skb->data & ~AX25_PF) == AX25_SABME) {
 400                ax25->modulus = AX25_EMODULUS;
 401                ax25->window  = ax25_dev->values[AX25_VALUES_EWINDOW];
 402        } else {
 403                ax25->modulus = AX25_MODULUS;
 404                ax25->window  = ax25_dev->values[AX25_VALUES_WINDOW];
 405        }
 406
 407        ax25_send_control(ax25, AX25_UA, AX25_POLLON, AX25_RESPONSE);
 408
 409#ifdef CONFIG_AX25_DAMA_SLAVE
 410        if (dama && ax25->ax25_dev->values[AX25_VALUES_PROTOCOL] == AX25_PROTO_DAMA_SLAVE)
 411                ax25_dama_on(ax25);
 412#endif
 413
 414        ax25->state = AX25_STATE_3;
 415
 416        ax25_cb_add(ax25);
 417
 418        ax25_start_heartbeat(ax25);
 419        ax25_start_t3timer(ax25);
 420        ax25_start_idletimer(ax25);
 421
 422        if (sk) {
 423                if (!sock_flag(sk, SOCK_DEAD))
 424                        sk->sk_data_ready(sk);
 425                sock_put(sk);
 426        } else {
 427free:
 428                kfree_skb(skb);
 429        }
 430        return 0;
 431}
 432
 433/*
 434 *      Receive an AX.25 frame via a SLIP interface.
 435 */
 436int ax25_kiss_rcv(struct sk_buff *skb, struct net_device *dev,
 437                  struct packet_type *ptype, struct net_device *orig_dev)
 438{
 439        skb_orphan(skb);
 440
 441        if (!net_eq(dev_net(dev), &init_net)) {
 442                kfree_skb(skb);
 443                return 0;
 444        }
 445
 446        if ((*skb->data & 0x0F) != 0) {
 447                kfree_skb(skb); /* Not a KISS data frame */
 448                return 0;
 449        }
 450
 451        skb_pull(skb, AX25_KISS_HEADER_LEN);    /* Remove the KISS byte */
 452
 453        return ax25_rcv(skb, dev, (ax25_address *)dev->dev_addr, ptype);
 454}
 455