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 <linux/slab.h>
  20 #include <net/ax25.h>
  21 #include <linux/inet.h>
  22 #include <linux/netdevice.h>
  23 #include <linux/if_arp.h>
  24 #include <linux/skbuff.h>
  25 #include <net/sock.h>
  26 #include <asm/uaccess.h>
  27 #include <asm/system.h>
  28 #include <linux/fcntl.h>
  29 #include <linux/termios.h>      /* For TIOCINQ/OUTQ */
  30 #include <linux/mm.h>
  31 #include <linux/interrupt.h>
  32 #include <linux/notifier.h>
  33 #include <linux/proc_fs.h>
  34 #include <linux/stat.h>
  35 #include <linux/netfilter.h>
  36 #include <linux/sysctl.h>
  37 #include <net/ip.h>
  38 #include <net/arp.h>
  39
  40 /*
  41  *      IP over AX.25 encapsulation.
  42  */
  43
  44 /*
  45  *      Shove an AX.25 UI header on an IP packet and handle ARP
  46  */
  47
  48 #ifdef CONFIG_INET
  49
  50 int ax25_hard_header(struct sk_buff *skb, struct net_device *dev,
  51                      unsigned short type, const void *daddr,
  52                      const void *saddr, unsigned len)
  53 {
  54         unsigned char *buff;
  55
  56         /* they sometimes come back to us... */
  57         if (type == ETH_P_AX25)
  58                 return 0;
  59
  60         /* header is an AX.25 UI frame from us to them */
  61         buff = skb_push(skb, AX25_HEADER_LEN);
  62         *buff++ = 0x00; /* KISS DATA */
  63
  64         if (daddr != NULL)
  65                 memcpy(buff, daddr, dev->addr_len);     /* Address specified */
  66
  67         buff[6] &= ~AX25_CBIT;
  68         buff[6] &= ~AX25_EBIT;
  69         buff[6] |= AX25_SSSID_SPARE;
  70         buff    += AX25_ADDR_LEN;
  71
  72         if (saddr != NULL)
  73                 memcpy(buff, saddr, dev->addr_len);
  74         else
  75                 memcpy(buff, dev->dev_addr, dev->addr_len);
  76
  77         buff[6] &= ~AX25_CBIT;
  78         buff[6] |= AX25_EBIT;
  79         buff[6] |= AX25_SSSID_SPARE;
  80         buff    += AX25_ADDR_LEN;
  81
  82         *buff++  = AX25_UI;     /* UI */
  83
  84         /* Append a suitable AX.25 PID */
  85         switch (type) {
  86         case ETH_P_IP:
  87                 *buff++ = AX25_P_IP;
  88                 break;
  89         case ETH_P_ARP:
  90                 *buff++ = AX25_P_ARP;
  91                 break;
  92         default:
  93                 printk(KERN_ERR "AX.25: ax25_hard_header - wrong protocol type 0x%2.2x\n", type);
  94                 *buff++ = 0;
  95                 break;
  96         }
  97
  98         if (daddr != NULL)
  99                 return AX25_HEADER_LEN;
 100
 101         return -AX25_HEADER_LEN;        /* Unfinished header */
 102 }
 103
 104 int ax25_rebuild_header(struct sk_buff *skb)
 105 {
 106         struct sk_buff *ourskb;
 107         unsigned char *bp  = skb->data;
 108         ax25_route *route;
 109         struct net_device *dev = NULL;
 110         ax25_address *src, *dst;
 111         ax25_digi *digipeat = NULL;
 112         ax25_dev *ax25_dev;
 113         ax25_cb *ax25;
 114         char ip_mode = ' ';
 115
 116         dst = (ax25_address *)(bp + 1);
 117         src = (ax25_address *)(bp + 8);
 118
 119         if (arp_find(bp + 1, skb))
 120                 return 1;
 121
 122         route = ax25_get_route(dst, NULL);
 123         if (route) {
 124                 digipeat = route->digipeat;
 125                 dev = route->dev;
 126                 ip_mode = route->ip_mode;
 127         }
 128
 129         if (dev == NULL)
 130                 dev = skb->dev;
 131
 132         if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) {
 133                 goto put;
 134         }
 135
 136         if (bp[16] == AX25_P_IP) {
 137                 if (ip_mode == 'V' || (ip_mode == ' ' && ax25_dev->values[AX25_VALUES_IPDEFMODE])) {
 138                         /*
 139                          *      We copy the buffer and release the original thereby
 140                          *      keeping it straight
 141                          *
 142                          *      Note: we report 1 back so the caller will
 143                          *      not feed the frame direct to the physical device
 144                          *      We don't want that to happen. (It won't be upset
 145                          *      as we have pulled the frame from the queue by
 146                          *      freeing it).
 147                          *
 148                          *      NB: TCP modifies buffers that are still
 149                          *      on a device queue, thus we use skb_copy()
 150                          *      instead of using skb_clone() unless this
 151                          *      gets fixed.
 152                          */
 153
 154                         ax25_address src_c;
 155                         ax25_address dst_c;
 156
 157                         if ((ourskb = skb_copy(skb, GFP_ATOMIC)) == NULL) {
 158                                 kfree_skb(skb);
 159                                 goto put;
 160                         }
 161
 162                         if (skb->sk != NULL)
 163                                 skb_set_owner_w(ourskb, skb->sk);
 164
 165                         kfree_skb(skb);
 166                         /* dl9sau: bugfix
 167                          * after kfree_skb(), dst and src which were pointer
 168                          * to bp which is part of skb->data would not be valid
 169                          * anymore hope that after skb_pull(ourskb, ..) our
 170                          * dsc_c and src_c will not become invalid
 171                          */
 172                         bp  = ourskb->data;
 173                         dst_c = *(ax25_address *)(bp + 1);
 174                         src_c = *(ax25_address *)(bp + 8);
 175
 176                         skb_pull(ourskb, AX25_HEADER_LEN - 1);  /* Keep PID */
 177                         skb_reset_network_header(ourskb);
 178
 179                         ax25=ax25_send_frame(
 180                             ourskb,
 181                             ax25_dev->values[AX25_VALUES_PACLEN],
 182                             &src_c,
 183                             &dst_c, digipeat, dev);
 184                         if (ax25) {
 185                                 ax25_cb_put(ax25);
 186                         }
 187                         goto put;
 188                 }
 189         }
 190
 191         bp[7]  &= ~AX25_CBIT;
 192         bp[7]  &= ~AX25_EBIT;
 193         bp[7]  |= AX25_SSSID_SPARE;
 194
 195         bp[14] &= ~AX25_CBIT;
 196         bp[14] |= AX25_EBIT;
 197         bp[14] |= AX25_SSSID_SPARE;
 198
 199         skb_pull(skb, AX25_KISS_HEADER_LEN);
 200
 201         if (digipeat != NULL) {
 202                 if ((ourskb = ax25_rt_build_path(skb, src, dst, route->digipeat)) == NULL) {
 203                         kfree_skb(skb);
 204                         goto put;
 205                 }
 206
 207                 skb = ourskb;
 208         }
 209
 210         ax25_queue_xmit(skb, dev);
 211
 212 put:
 213         if (route)
 214                 ax25_put_route(route);
 215
 216         return 1;
 217 }
 218
 219 #else   /* INET */
 220
 221 int ax25_hard_header(struct sk_buff *skb, struct net_device *dev,
 222                      unsigned short type, const void *daddr,
 223                      const void *saddr, unsigned len)
 224 {
 225         return -AX25_HEADER_LEN;
 226 }
 227
 228 int ax25_rebuild_header(struct sk_buff *skb)
 229 {
 230         return 1;
 231 }
 232
 233 #endif
 234
 235 const struct header_ops ax25_header_ops = {
 236         .create = ax25_hard_header,
 237         .rebuild = ax25_rebuild_header,
 238 };
 239
 240 EXPORT_SYMBOL(ax25_hard_header);
 241 EXPORT_SYMBOL(ax25_rebuild_header);
 242 EXPORT_SYMBOL(ax25_header_ops);
 243