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/config.h>
  10 #include <linux/errno.h>
  11 #include <linux/types.h>
  12 #include <linux/socket.h>
  13 #include <linux/in.h>
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/sched.h>
  17 #include <linux/timer.h>
  18 #include <linux/string.h>
  19 #include <linux/sockios.h>
  20 #include <linux/net.h>
  21 #include <net/ax25.h>
  22 #include <linux/inet.h>
  23 #include <linux/netdevice.h>
  24 #include <linux/if_arp.h>
  25 #include <linux/skbuff.h>
  26 #include <net/sock.h>
  27 #include <asm/uaccess.h>
  28 #include <asm/system.h>
  29 #include <linux/fcntl.h>
  30 #include <linux/termios.h>      /* For TIOCINQ/OUTQ */
  31 #include <linux/mm.h>
  32 #include <linux/interrupt.h>
  33 #include <linux/notifier.h>
  34 #include <linux/proc_fs.h>
  35 #include <linux/stat.h>
  36 #include <linux/netfilter.h>
  37 #include <linux/sysctl.h>
  38 #include <net/ip.h>
  39 #include <net/arp.h>
  40
  41 /*
  42  *      IP over AX.25 encapsulation.
  43  */
  44
  45 /*
  46  *      Shove an AX.25 UI header on an IP packet and handle ARP
  47  */
  48
  49 #ifdef CONFIG_INET
  50
  51 int ax25_hard_header(struct sk_buff *skb, struct net_device *dev, unsigned short type, void *daddr, 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         struct net_device *dev;
 108         ax25_address *src, *dst;
 109         ax25_dev *ax25_dev;
 110         ax25_route _route, *route = &_route;
 111         ax25_cb *ax25;
 112
 113         dst = (ax25_address *)(bp + 1);
 114         src = (ax25_address *)(bp + 8);
 115
 116         if (arp_find(bp + 1, skb))
 117                 return 1;
 118
 119         route = ax25_rt_find_route(route, dst, NULL);
 120         dev      = route->dev;
 121
 122         if (dev == NULL)
 123                 dev = skb->dev;
 124
 125         if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) {
 126                 goto put;
 127         }
 128
 129         if (bp[16] == AX25_P_IP) {
 130                 if (route->ip_mode == 'V' || (route->ip_mode == ' ' && ax25_dev->values[AX25_VALUES_IPDEFMODE])) {
 131                         /*
 132                          *      We copy the buffer and release the original thereby
 133                          *      keeping it straight
 134                          *
 135                          *      Note: we report 1 back so the caller will
 136                          *      not feed the frame direct to the physical device
 137                          *      We don't want that to happen. (It won't be upset
 138                          *      as we have pulled the frame from the queue by
 139                          *      freeing it).
 140                          *
 141                          *      NB: TCP modifies buffers that are still
 142                          *      on a device queue, thus we use skb_copy()
 143                          *      instead of using skb_clone() unless this
 144                          *      gets fixed.
 145                          */
 146
 147                         ax25_address src_c;
 148                         ax25_address dst_c;
 149
 150                         if ((ourskb = skb_copy(skb, GFP_ATOMIC)) == NULL) {
 151                                 kfree_skb(skb);
 152                                 goto put;
 153                         }
 154
 155                         if (skb->sk != NULL)
 156                                 skb_set_owner_w(ourskb, skb->sk);
 157
 158                         kfree_skb(skb);
 159                         /* dl9sau: bugfix
 160                          * after kfree_skb(), dst and src which were pointer
 161                          * to bp which is part of skb->data would not be valid
 162                          * anymore hope that after skb_pull(ourskb, ..) our
 163                          * dsc_c and src_c will not become invalid
 164                          */
 165                         bp  = ourskb->data;
 166                         dst_c = *(ax25_address *)(bp + 1);
 167                         src_c = *(ax25_address *)(bp + 8);
 168
 169                         skb_pull(ourskb, AX25_HEADER_LEN - 1);  /* Keep PID */
 170                         ourskb->nh.raw = ourskb->data;
 171
 172                         ax25=ax25_send_frame(
 173                             ourskb,
 174                             ax25_dev->values[AX25_VALUES_PACLEN],
 175                             &src_c,
 176                             &dst_c, route->digipeat, dev);
 177                         if (ax25) {
 178                                 ax25_cb_put(ax25);
 179                         }
 180                         goto put;
 181                 }
 182         }
 183
 184         bp[7]  &= ~AX25_CBIT;
 185         bp[7]  &= ~AX25_EBIT;
 186         bp[7]  |= AX25_SSSID_SPARE;
 187
 188         bp[14] &= ~AX25_CBIT;
 189         bp[14] |= AX25_EBIT;
 190         bp[14] |= AX25_SSSID_SPARE;
 191
 192         skb_pull(skb, AX25_KISS_HEADER_LEN);
 193
 194         if (route->digipeat != NULL) {
 195                 if ((ourskb = ax25_rt_build_path(skb, src, dst, route->digipeat)) == NULL) {
 196                         kfree_skb(skb);
 197                         goto put;
 198                 }
 199
 200                 skb = ourskb;
 201         }
 202
 203         ax25_queue_xmit(skb, dev);
 204
 205 put:
 206         ax25_put_route(route);
 207
 208         return 1;
 209 }
 210
 211 #else   /* INET */
 212
 213 int ax25_hard_header(struct sk_buff *skb, struct net_device *dev, unsigned short type, void *daddr, void *saddr, unsigned len)
 214 {
 215         return -AX25_HEADER_LEN;
 216 }
 217
 218 int ax25_rebuild_header(struct sk_buff *skb)
 219 {
 220         return 1;
 221 }
 222
 223 #endif
 224
 225 EXPORT_SYMBOL(ax25_hard_header);
 226 EXPORT_SYMBOL(ax25_rebuild_header);