net/ax25/ax25_ip.c

   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) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   8  */
   9 #include <linux/errno.h>
  10 #include <linux/types.h>
  11 #include <linux/socket.h>
  12 #include <linux/in.h>
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/timer.h>
  16 #include <linux/string.h>
  17 #include <linux/sockios.h>
  18 #include <linux/net.h>
  19 #include <net/ax25.h>
  20 #include <linux/inet.h>
  21 #include <linux/netdevice.h>
  22 #include <linux/if_arp.h>
  23 #include <linux/skbuff.h>
  24 #include <net/sock.h>
  25 #include <asm/uaccess.h>
  26 #include <asm/system.h>
  27 #include <linux/fcntl.h>
  28 #include <linux/termios.h>      /* For TIOCINQ/OUTQ */
  29 #include <linux/mm.h>
  30 #include <linux/interrupt.h>
  31 #include <linux/notifier.h>
  32 #include <linux/proc_fs.h>
  33 #include <linux/stat.h>
  34 #include <linux/netfilter.h>
  35 #include <linux/sysctl.h>
  36 #include <net/ip.h>
  37 #include <net/arp.h>
  38
  39 /*
  40  *      IP over AX.25 encapsulation.
  41  */
  42
  43 /*
  44  *      Shove an AX.25 UI header on an IP packet and handle ARP
  45  */
  46
  47 #ifdef CONFIG_INET
  48
  49 int ax25_hard_header(struct sk_buff *skb, struct net_device *dev,
  50                      unsigned short type, const void *daddr,
  51                      const void *saddr, unsigned len)
  52 {
  53         unsigned char *buff;
  54
  55         /* they sometimes come back to us... */
  56         if (type == ETH_P_AX25)
  57                 return 0;
  58
  59         /* header is an AX.25 UI frame from us to them */
  60         buff = skb_push(skb, AX25_HEADER_LEN);
  61         *buff++ = 0x00; /* KISS DATA */
  62
  63         if (daddr != NULL)
  64                 memcpy(buff, daddr, dev->addr_len);     /* Address specified */
  65
  66         buff[6] &= ~AX25_CBIT;
  67         buff[6] &= ~AX25_EBIT;
  68         buff[6] |= AX25_SSSID_SPARE;
  69         buff    += AX25_ADDR_LEN;
  70
  71         if (saddr != NULL)
  72                 memcpy(buff, saddr, dev->addr_len);
  73         else
  74                 memcpy(buff, dev->dev_addr, dev->addr_len);
  75
  76         buff[6] &= ~AX25_CBIT;
  77         buff[6] |= AX25_EBIT;
  78         buff[6] |= AX25_SSSID_SPARE;
  79         buff    += AX25_ADDR_LEN;
  80
  81         *buff++  = AX25_UI;     /* UI */
  82
  83         /* Append a suitable AX.25 PID */
  84         switch (type) {
  85         case ETH_P_IP:
  86                 *buff++ = AX25_P_IP;
  87                 break;
  88         case ETH_P_ARP:
  89                 *buff++ = AX25_P_ARP;
  90                 break;
  91         default:
  92                 printk(KERN_ERR "AX.25: ax25_hard_header - wrong protocol type 0x%2.2x\n", type);
  93                 *buff++ = 0;
  94                 break;
  95         }
  96
  97         if (daddr != NULL)
  98                 return AX25_HEADER_LEN;
  99
 100         return -AX25_HEADER_LEN;        /* Unfinished header */
 101 }
 102
 103 int ax25_rebuild_header(struct sk_buff *skb)
 104 {
 105         struct sk_buff *ourskb;
 106         unsigned char *bp  = skb->data;
 107         ax25_route *route;
 108         struct net_device *dev = NULL;
 109         ax25_address *src, *dst;
 110         ax25_digi *digipeat = NULL;
 111         ax25_dev *ax25_dev;
 112         ax25_cb *ax25;
 113         char ip_mode = ' ';
 114
 115         dst = (ax25_address *)(bp + 1);
 116         src = (ax25_address *)(bp + 8);
 117
 118         if (arp_find(bp + 1, skb))
 119                 return 1;
 120
 121         route = ax25_get_route(dst, NULL);
 122         if (route) {
 123                 digipeat = route->digipeat;
 124                 dev = route->dev;
 125                 ip_mode = route->ip_mode;
 126         }
 127
 128         if (dev == NULL)
 129                 dev = skb->dev;
 130
 131         if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) {
 132                 goto put;
 133         }
 134
 135         if (bp[16] == AX25_P_IP) {
 136                 if (ip_mode == 'V' || (ip_mode == ' ' && ax25_dev->values[AX25_VALUES_IPDEFMODE])) {
 137                         /*
 138                          *      We copy the buffer and release the original thereby
 139                          *      keeping it straight
 140                          *
 141                          *      Note: we report 1 back so the caller will
 142                          *      not feed the frame direct to the physical device
 143                          *      We don't want that to happen. (It won't be upset
 144                          *      as we have pulled the frame from the queue by
 145                          *      freeing it).
 146                          *
 147                          *      NB: TCP modifies buffers that are still
 148                          *      on a device queue, thus we use skb_copy()
 149                          *      instead of using skb_clone() unless this
 150                          *      gets fixed.
 151                          */
 152
 153                         ax25_address src_c;
 154                         ax25_address dst_c;
 155
 156                         if ((ourskb = skb_copy(skb, GFP_ATOMIC)) == NULL) {
 157                                 kfree_skb(skb);
 158                                 goto put;
 159                         }
 160
 161                         if (skb->sk != NULL)
 162                                 skb_set_owner_w(ourskb, skb->sk);
 163
 164                         kfree_skb(skb);
 165                         /* dl9sau: bugfix
 166                          * after kfree_skb(), dst and src which were pointer
 167                          * to bp which is part of skb->data would not be valid
 168                          * anymore hope that after skb_pull(ourskb, ..) our
 169                          * dsc_c and src_c will not become invalid
 170                          */
 171                         bp  = ourskb->data;
 172                         dst_c = *(ax25_address *)(bp + 1);
 173                         src_c = *(ax25_address *)(bp + 8);
 174
 175                         skb_pull(ourskb, AX25_HEADER_LEN - 1);  /* Keep PID */
 176                         skb_reset_network_header(ourskb);
 177
 178                         ax25=ax25_send_frame(
 179                             ourskb,
 180                             ax25_dev->values[AX25_VALUES_PACLEN],
 181                             &src_c,
 182                             &dst_c, digipeat, dev);
 183                         if (ax25) {
 184                                 ax25_cb_put(ax25);
 185                         }
 186                         goto put;
 187                 }
 188         }
 189
 190         bp[7]  &= ~AX25_CBIT;
 191         bp[7]  &= ~AX25_EBIT;
 192         bp[7]  |= AX25_SSSID_SPARE;
 193
 194         bp[14] &= ~AX25_CBIT;
 195         bp[14] |= AX25_EBIT;
 196         bp[14] |= AX25_SSSID_SPARE;
 197
 198         skb_pull(skb, AX25_KISS_HEADER_LEN);
 199
 200         if (digipeat != NULL) {
 201                 if ((ourskb = ax25_rt_build_path(skb, src, dst, route->digipeat)) == NULL) {
 202                         kfree_skb(skb);
 203                         goto put;
 204                 }
 205
 206                 skb = ourskb;
 207         }
 208
 209         ax25_queue_xmit(skb, dev);
 210
 211 put:
 212         if (route)
 213                 ax25_put_route(route);
 214
 215         return 1;
 216 }
 217
 218 #else   /* INET */
 219
 220 int ax25_hard_header(struct sk_buff *skb, struct net_device *dev,
 221                      unsigned short type, const void *daddr,
 222                      const void *saddr, unsigned len)
 223 {
 224         return -AX25_HEADER_LEN;
 225 }
 226
 227 int ax25_rebuild_header(struct sk_buff *skb)
 228 {
 229         return 1;
 230 }
 231
 232 #endif
 233
 234 const struct header_ops ax25_header_ops = {
 235         .create = ax25_hard_header,
 236         .rebuild = ax25_rebuild_header,
 237 };
 238
 239 EXPORT_SYMBOL(ax25_hard_header);
 240 EXPORT_SYMBOL(ax25_rebuild_header);
 241 EXPORT_SYMBOL(ax25_header_ops);
 242