linux/net/x25/x25_dev.c
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   1/*
   2 *      X.25 Packet Layer release 002
   3 *
   4 *      This is ALPHA test software. This code may break your machine, randomly fail to work with new
   5 *      releases, misbehave and/or generally screw up. It might even work.
   6 *
   7 *      This code REQUIRES 2.1.15 or higher
   8 *
   9 *      This module:
  10 *              This module is free software; you can redistribute it and/or
  11 *              modify it under the terms of the GNU General Public License
  12 *              as published by the Free Software Foundation; either version
  13 *              2 of the License, or (at your option) any later version.
  14 *
  15 *      History
  16 *      X.25 001        Jonathan Naylor Started coding.
  17 *      2000-09-04      Henner Eisen    Prevent freeing a dangling skb.
  18 */
  19
  20#include <linux/kernel.h>
  21#include <linux/netdevice.h>
  22#include <linux/skbuff.h>
  23#include <linux/slab.h>
  24#include <net/sock.h>
  25#include <linux/if_arp.h>
  26#include <net/x25.h>
  27#include <net/x25device.h>
  28
  29static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb)
  30{
  31        struct sock *sk;
  32        unsigned short frametype;
  33        unsigned int lci;
  34
  35        if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
  36                return 0;
  37
  38        frametype = skb->data[2];
  39        lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
  40
  41        /*
  42         *      LCI of zero is always for us, and its always a link control
  43         *      frame.
  44         */
  45        if (lci == 0) {
  46                x25_link_control(skb, nb, frametype);
  47                return 0;
  48        }
  49
  50        /*
  51         *      Find an existing socket.
  52         */
  53        if ((sk = x25_find_socket(lci, nb)) != NULL) {
  54                int queued = 1;
  55
  56                skb_reset_transport_header(skb);
  57                bh_lock_sock(sk);
  58                if (!sock_owned_by_user(sk)) {
  59                        queued = x25_process_rx_frame(sk, skb);
  60                } else {
  61                        queued = !sk_add_backlog(sk, skb, sk->sk_rcvbuf);
  62                }
  63                bh_unlock_sock(sk);
  64                sock_put(sk);
  65                return queued;
  66        }
  67
  68        /*
  69         *      Is is a Call Request ? if so process it.
  70         */
  71        if (frametype == X25_CALL_REQUEST)
  72                return x25_rx_call_request(skb, nb, lci);
  73
  74        /*
  75         *      Its not a Call Request, nor is it a control frame.
  76         *      Can we forward it?
  77         */
  78
  79        if (x25_forward_data(lci, nb, skb)) {
  80                if (frametype == X25_CLEAR_CONFIRMATION) {
  81                        x25_clear_forward_by_lci(lci);
  82                }
  83                kfree_skb(skb);
  84                return 1;
  85        }
  86
  87/*
  88        x25_transmit_clear_request(nb, lci, 0x0D);
  89*/
  90
  91        if (frametype != X25_CLEAR_CONFIRMATION)
  92                printk(KERN_DEBUG "x25_receive_data(): unknown frame type %2x\n",frametype);
  93
  94        return 0;
  95}
  96
  97int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,
  98                           struct packet_type *ptype, struct net_device *orig_dev)
  99{
 100        struct sk_buff *nskb;
 101        struct x25_neigh *nb;
 102
 103        if (!net_eq(dev_net(dev), &init_net))
 104                goto drop;
 105
 106        nskb = skb_copy(skb, GFP_ATOMIC);
 107        if (!nskb)
 108                goto drop;
 109        kfree_skb(skb);
 110        skb = nskb;
 111
 112        /*
 113         * Packet received from unrecognised device, throw it away.
 114         */
 115        nb = x25_get_neigh(dev);
 116        if (!nb) {
 117                printk(KERN_DEBUG "X.25: unknown neighbour - %s\n", dev->name);
 118                goto drop;
 119        }
 120
 121        if (!pskb_may_pull(skb, 1))
 122                return 0;
 123
 124        switch (skb->data[0]) {
 125
 126        case X25_IFACE_DATA:
 127                skb_pull(skb, 1);
 128                if (x25_receive_data(skb, nb)) {
 129                        x25_neigh_put(nb);
 130                        goto out;
 131                }
 132                break;
 133
 134        case X25_IFACE_CONNECT:
 135                x25_link_established(nb);
 136                break;
 137
 138        case X25_IFACE_DISCONNECT:
 139                x25_link_terminated(nb);
 140                break;
 141        }
 142        x25_neigh_put(nb);
 143drop:
 144        kfree_skb(skb);
 145out:
 146        return 0;
 147}
 148
 149void x25_establish_link(struct x25_neigh *nb)
 150{
 151        struct sk_buff *skb;
 152        unsigned char *ptr;
 153
 154        switch (nb->dev->type) {
 155        case ARPHRD_X25:
 156                if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {
 157                        printk(KERN_ERR "x25_dev: out of memory\n");
 158                        return;
 159                }
 160                ptr  = skb_put(skb, 1);
 161                *ptr = X25_IFACE_CONNECT;
 162                break;
 163
 164#if IS_ENABLED(CONFIG_LLC)
 165        case ARPHRD_ETHER:
 166                return;
 167#endif
 168        default:
 169                return;
 170        }
 171
 172        skb->protocol = htons(ETH_P_X25);
 173        skb->dev      = nb->dev;
 174
 175        dev_queue_xmit(skb);
 176}
 177
 178void x25_terminate_link(struct x25_neigh *nb)
 179{
 180        struct sk_buff *skb;
 181        unsigned char *ptr;
 182
 183#if IS_ENABLED(CONFIG_LLC)
 184        if (nb->dev->type == ARPHRD_ETHER)
 185                return;
 186#endif
 187        if (nb->dev->type != ARPHRD_X25)
 188                return;
 189
 190        skb = alloc_skb(1, GFP_ATOMIC);
 191        if (!skb) {
 192                printk(KERN_ERR "x25_dev: out of memory\n");
 193                return;
 194        }
 195
 196        ptr  = skb_put(skb, 1);
 197        *ptr = X25_IFACE_DISCONNECT;
 198
 199        skb->protocol = htons(ETH_P_X25);
 200        skb->dev      = nb->dev;
 201        dev_queue_xmit(skb);
 202}
 203
 204void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)
 205{
 206        unsigned char *dptr;
 207
 208        skb_reset_network_header(skb);
 209
 210        switch (nb->dev->type) {
 211        case ARPHRD_X25:
 212                dptr  = skb_push(skb, 1);
 213                *dptr = X25_IFACE_DATA;
 214                break;
 215
 216#if IS_ENABLED(CONFIG_LLC)
 217        case ARPHRD_ETHER:
 218                kfree_skb(skb);
 219                return;
 220#endif
 221        default:
 222                kfree_skb(skb);
 223                return;
 224        }
 225
 226        skb->protocol = htons(ETH_P_X25);
 227        skb->dev      = nb->dev;
 228
 229        dev_queue_xmit(skb);
 230}
 231
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