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 #define pr_fmt(fmt) "X25: " fmt
  21
  22 #include <linux/kernel.h>
  23 #include <linux/netdevice.h>
  24 #include <linux/skbuff.h>
  25 #include <linux/slab.h>
  26 #include <net/sock.h>
  27 #include <linux/if_arp.h>
  28 #include <net/x25.h>
  29 #include <net/x25device.h>
  30
  31 static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb)
  32 {
  33         struct sock *sk;
  34         unsigned short frametype;
  35         unsigned int lci;
  36
  37         if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
  38                 return 0;
  39
  40         frametype = skb->data[2];
  41         lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
  42
  43         /*
  44          *      LCI of zero is always for us, and its always a link control
  45          *      frame.
  46          */
  47         if (lci == 0) {
  48                 x25_link_control(skb, nb, frametype);
  49                 return 0;
  50         }
  51
  52         /*
  53          *      Find an existing socket.
  54          */
  55         if ((sk = x25_find_socket(lci, nb)) != NULL) {
  56                 int queued = 1;
  57
  58                 skb_reset_transport_header(skb);
  59                 bh_lock_sock(sk);
  60                 if (!sock_owned_by_user(sk)) {
  61                         queued = x25_process_rx_frame(sk, skb);
  62                 } else {
  63                         queued = !sk_add_backlog(sk, skb, sk->sk_rcvbuf);
  64                 }
  65                 bh_unlock_sock(sk);
  66                 sock_put(sk);
  67                 return queued;
  68         }
  69
  70         /*
  71          *      Is is a Call Request ? if so process it.
  72          */
  73         if (frametype == X25_CALL_REQUEST)
  74                 return x25_rx_call_request(skb, nb, lci);
  75
  76         /*
  77          *      Its not a Call Request, nor is it a control frame.
  78          *      Can we forward it?
  79          */
  80
  81         if (x25_forward_data(lci, nb, skb)) {
  82                 if (frametype == X25_CLEAR_CONFIRMATION) {
  83                         x25_clear_forward_by_lci(lci);
  84                 }
  85                 kfree_skb(skb);
  86                 return 1;
  87         }
  88
  89 /*
  90         x25_transmit_clear_request(nb, lci, 0x0D);
  91 */
  92
  93         if (frametype != X25_CLEAR_CONFIRMATION)
  94                 pr_debug("x25_receive_data(): unknown frame type %2x\n",frametype);
  95
  96         return 0;
  97 }
  98
  99 int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,
 100                            struct packet_type *ptype, struct net_device *orig_dev)
 101 {
 102         struct sk_buff *nskb;
 103         struct x25_neigh *nb;
 104
 105         if (!net_eq(dev_net(dev), &init_net))
 106                 goto drop;
 107
 108         nskb = skb_copy(skb, GFP_ATOMIC);
 109         if (!nskb)
 110                 goto drop;
 111         kfree_skb(skb);
 112         skb = nskb;
 113
 114         /*
 115          * Packet received from unrecognised device, throw it away.
 116          */
 117         nb = x25_get_neigh(dev);
 118         if (!nb) {
 119                 pr_debug("unknown neighbour - %s\n", dev->name);
 120                 goto drop;
 121         }
 122
 123         if (!pskb_may_pull(skb, 1)) {
 124                 x25_neigh_put(nb);
 125                 return 0;
 126         }
 127
 128         switch (skb->data[0]) {
 129
 130         case X25_IFACE_DATA:
 131                 skb_pull(skb, 1);
 132                 if (x25_receive_data(skb, nb)) {
 133                         x25_neigh_put(nb);
 134                         goto out;
 135                 }
 136                 break;
 137
 138         case X25_IFACE_CONNECT:
 139                 x25_link_established(nb);
 140                 break;
 141
 142         case X25_IFACE_DISCONNECT:
 143                 x25_link_terminated(nb);
 144                 break;
 145         }
 146         x25_neigh_put(nb);
 147 drop:
 148         kfree_skb(skb);
 149 out:
 150         return 0;
 151 }
 152
 153 void x25_establish_link(struct x25_neigh *nb)
 154 {
 155         struct sk_buff *skb;
 156         unsigned char *ptr;
 157
 158         switch (nb->dev->type) {
 159         case ARPHRD_X25:
 160                 if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {
 161                         pr_err("x25_dev: out of memory\n");
 162                         return;
 163                 }
 164                 ptr  = skb_put(skb, 1);
 165                 *ptr = X25_IFACE_CONNECT;
 166                 break;
 167
 168 #if IS_ENABLED(CONFIG_LLC)
 169         case ARPHRD_ETHER:
 170                 return;
 171 #endif
 172         default:
 173                 return;
 174         }
 175
 176         skb->protocol = htons(ETH_P_X25);
 177         skb->dev      = nb->dev;
 178
 179         dev_queue_xmit(skb);
 180 }
 181
 182 void x25_terminate_link(struct x25_neigh *nb)
 183 {
 184         struct sk_buff *skb;
 185         unsigned char *ptr;
 186
 187 #if IS_ENABLED(CONFIG_LLC)
 188         if (nb->dev->type == ARPHRD_ETHER)
 189                 return;
 190 #endif
 191         if (nb->dev->type != ARPHRD_X25)
 192                 return;
 193
 194         skb = alloc_skb(1, GFP_ATOMIC);
 195         if (!skb) {
 196                 pr_err("x25_dev: out of memory\n");
 197                 return;
 198         }
 199
 200         ptr  = skb_put(skb, 1);
 201         *ptr = X25_IFACE_DISCONNECT;
 202
 203         skb->protocol = htons(ETH_P_X25);
 204         skb->dev      = nb->dev;
 205         dev_queue_xmit(skb);
 206 }
 207
 208 void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)
 209 {
 210         unsigned char *dptr;
 211
 212         skb_reset_network_header(skb);
 213
 214         switch (nb->dev->type) {
 215         case ARPHRD_X25:
 216                 dptr  = skb_push(skb, 1);
 217                 *dptr = X25_IFACE_DATA;
 218                 break;
 219
 220 #if IS_ENABLED(CONFIG_LLC)
 221         case ARPHRD_ETHER:
 222                 kfree_skb(skb);
 223                 return;
 224 #endif
 225         default:
 226                 kfree_skb(skb);
 227                 return;
 228         }
 229
 230         skb->protocol = htons(ETH_P_X25);
 231         skb->dev      = nb->dev;
 232
 233         dev_queue_xmit(skb);
 234 }