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 <linux/uaccess.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/sysctl.h>
  35 #include <net/ip.h>
  36 #include <net/arp.h>
  37
  38 /*
  39  *      IP over AX.25 encapsulation.
  40  */
  41
  42 /*
  43  *      Shove an AX.25 UI header on an IP packet and handle ARP
  44  */
  45
  46 #ifdef CONFIG_INET
  47
  48 static int ax25_hard_header(struct sk_buff *skb, struct net_device *dev,
  49                             unsigned short type, const void *daddr,
  50                             const void *saddr, unsigned int len)
  51 {
  52         unsigned char *buff;
  53
  54         /* they sometimes come back to us... */
  55         if (type == ETH_P_AX25)
  56                 return 0;
  57
  58         /* header is an AX.25 UI frame from us to them */
  59         buff = skb_push(skb, AX25_HEADER_LEN);
  60         *buff++ = 0x00; /* KISS DATA */
  61
  62         if (daddr != NULL)
  63                 memcpy(buff, daddr, dev->addr_len);     /* Address specified */
  64
  65         buff[6] &= ~AX25_CBIT;
  66         buff[6] &= ~AX25_EBIT;
  67         buff[6] |= AX25_SSSID_SPARE;
  68         buff    += AX25_ADDR_LEN;
  69
  70         if (saddr != NULL)
  71                 memcpy(buff, saddr, dev->addr_len);
  72         else
  73                 memcpy(buff, dev->dev_addr, dev->addr_len);
  74
  75         buff[6] &= ~AX25_CBIT;
  76         buff[6] |= AX25_EBIT;
  77         buff[6] |= AX25_SSSID_SPARE;
  78         buff    += AX25_ADDR_LEN;
  79
  80         *buff++  = AX25_UI;     /* UI */
  81
  82         /* Append a suitable AX.25 PID */
  83         switch (type) {
  84         case ETH_P_IP:
  85                 *buff++ = AX25_P_IP;
  86                 break;
  87         case ETH_P_ARP:
  88                 *buff++ = AX25_P_ARP;
  89                 break;
  90         default:
  91                 printk(KERN_ERR "AX.25: ax25_hard_header - wrong protocol type 0x%2.2x\n", type);
  92                 *buff++ = 0;
  93                 break;
  94         }
  95
  96         if (daddr != NULL)
  97                 return AX25_HEADER_LEN;
  98
  99         return -AX25_HEADER_LEN;        /* Unfinished header */
 100 }
 101
 102 netdev_tx_t ax25_ip_xmit(struct sk_buff *skb)
 103 {
 104         struct sk_buff *ourskb;
 105         unsigned char *bp  = skb->data;
 106         ax25_route *route;
 107         struct net_device *dev = NULL;
 108         ax25_address *src, *dst;
 109         ax25_digi *digipeat = NULL;
 110         ax25_dev *ax25_dev;
 111         ax25_cb *ax25;
 112         char ip_mode = ' ';
 113
 114         dst = (ax25_address *)(bp + 1);
 115         src = (ax25_address *)(bp + 8);
 116
 117         ax25_route_lock_use();
 118         route = ax25_get_route(dst, NULL);
 119         if (route) {
 120                 digipeat = route->digipeat;
 121                 dev = route->dev;
 122                 ip_mode = route->ip_mode;
 123         }
 124
 125         if (dev == NULL)
 126                 dev = skb->dev;
 127
 128         if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) {
 129                 kfree_skb(skb);
 130                 goto put;
 131         }
 132
 133         if (bp[16] == AX25_P_IP) {
 134                 if (ip_mode == 'V' || (ip_mode == ' ' && ax25_dev->values[AX25_VALUES_IPDEFMODE])) {
 135                         /*
 136                          *      We copy the buffer and release the original thereby
 137                          *      keeping it straight
 138                          *
 139                          *      Note: we report 1 back so the caller will
 140                          *      not feed the frame direct to the physical device
 141                          *      We don't want that to happen. (It won't be upset
 142                          *      as we have pulled the frame from the queue by
 143                          *      freeing it).
 144                          *
 145                          *      NB: TCP modifies buffers that are still
 146                          *      on a device queue, thus we use skb_copy()
 147                          *      instead of using skb_clone() unless this
 148                          *      gets fixed.
 149                          */
 150
 151                         ax25_address src_c;
 152                         ax25_address dst_c;
 153
 154                         if ((ourskb = skb_copy(skb, GFP_ATOMIC)) == NULL) {
 155                                 kfree_skb(skb);
 156                                 goto put;
 157                         }
 158
 159                         if (skb->sk != NULL)
 160                                 skb_set_owner_w(ourskb, skb->sk);
 161
 162                         kfree_skb(skb);
 163                         /* dl9sau: bugfix
 164                          * after kfree_skb(), dst and src which were pointer
 165                          * to bp which is part of skb->data would not be valid
 166                          * anymore hope that after skb_pull(ourskb, ..) our
 167                          * dsc_c and src_c will not become invalid
 168                          */
 169                         bp  = ourskb->data;
 170                         dst_c = *(ax25_address *)(bp + 1);
 171                         src_c = *(ax25_address *)(bp + 8);
 172
 173                         skb_pull(ourskb, AX25_HEADER_LEN - 1);  /* Keep PID */
 174                         skb_reset_network_header(ourskb);
 175
 176                         ax25=ax25_send_frame(
 177                             ourskb,
 178                             ax25_dev->values[AX25_VALUES_PACLEN],
 179                             &src_c,
 180                             &dst_c, digipeat, dev);
 181                         if (ax25) {
 182                                 ax25_cb_put(ax25);
 183                         }
 184                         goto put;
 185                 }
 186         }
 187
 188         bp[7]  &= ~AX25_CBIT;
 189         bp[7]  &= ~AX25_EBIT;
 190         bp[7]  |= AX25_SSSID_SPARE;
 191
 192         bp[14] &= ~AX25_CBIT;
 193         bp[14] |= AX25_EBIT;
 194         bp[14] |= AX25_SSSID_SPARE;
 195
 196         skb_pull(skb, AX25_KISS_HEADER_LEN);
 197
 198         if (digipeat != NULL) {
 199                 if ((ourskb = ax25_rt_build_path(skb, src, dst, route->digipeat)) == NULL) {
 200                         kfree_skb(skb);
 201                         goto put;
 202                 }
 203
 204                 skb = ourskb;
 205         }
 206
 207         ax25_queue_xmit(skb, dev);
 208
 209 put:
 210
 211         ax25_route_lock_unuse();
 212         return NETDEV_TX_OK;
 213 }
 214
 215 #else   /* INET */
 216
 217 static int ax25_hard_header(struct sk_buff *skb, struct net_device *dev,
 218                             unsigned short type, const void *daddr,
 219                             const void *saddr, unsigned int len)
 220 {
 221         return -AX25_HEADER_LEN;
 222 }
 223
 224 netdev_tx_t ax25_ip_xmit(struct sk_buff *skb)
 225 {
 226         kfree_skb(skb);
 227         return NETDEV_TX_OK;
 228 }
 229 #endif
 230
 231 static bool ax25_validate_header(const char *header, unsigned int len)
 232 {
 233         ax25_digi digi;
 234
 235         if (!len)
 236                 return false;
 237
 238         if (header[0])
 239                 return true;
 240
 241         return ax25_addr_parse(header + 1, len - 1, NULL, NULL, &digi, NULL,
 242                                NULL);
 243 }
 244
 245 const struct header_ops ax25_header_ops = {
 246         .create = ax25_hard_header,
 247         .validate = ax25_validate_header,
 248 };
 249
 250 EXPORT_SYMBOL(ax25_header_ops);
 251 EXPORT_SYMBOL(ax25_ip_xmit);