net/x25/x25_dev.c

   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
  29 static 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);
  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
  97 int 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);
 143 drop:
 144         kfree_skb(skb);
 145 out:
 146         return 0;
 147 }
 148
 149 void 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
 178 void 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
 204 void 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 }