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Linux/net/ax25/ax25_ip.c

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  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         route = ax25_get_route(dst, NULL);
118         if (route) {
119                 digipeat = route->digipeat;
120                 dev = route->dev;
121                 ip_mode = route->ip_mode;
122         }
123 
124         if (dev == NULL)
125                 dev = skb->dev;
126 
127         if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) {
128                 kfree_skb(skb);
129                 goto put;
130         }
131 
132         if (bp[16] == AX25_P_IP) {
133                 if (ip_mode == 'V' || (ip_mode == ' ' && ax25_dev->values[AX25_VALUES_IPDEFMODE])) {
134                         /*
135                          *      We copy the buffer and release the original thereby
136                          *      keeping it straight
137                          *
138                          *      Note: we report 1 back so the caller will
139                          *      not feed the frame direct to the physical device
140                          *      We don't want that to happen. (It won't be upset
141                          *      as we have pulled the frame from the queue by
142                          *      freeing it).
143                          *
144                          *      NB: TCP modifies buffers that are still
145                          *      on a device queue, thus we use skb_copy()
146                          *      instead of using skb_clone() unless this
147                          *      gets fixed.
148                          */
149 
150                         ax25_address src_c;
151                         ax25_address dst_c;
152 
153                         if ((ourskb = skb_copy(skb, GFP_ATOMIC)) == NULL) {
154                                 kfree_skb(skb);
155                                 goto put;
156                         }
157 
158                         if (skb->sk != NULL)
159                                 skb_set_owner_w(ourskb, skb->sk);
160 
161                         kfree_skb(skb);
162                         /* dl9sau: bugfix
163                          * after kfree_skb(), dst and src which were pointer
164                          * to bp which is part of skb->data would not be valid
165                          * anymore hope that after skb_pull(ourskb, ..) our
166                          * dsc_c and src_c will not become invalid
167                          */
168                         bp  = ourskb->data;
169                         dst_c = *(ax25_address *)(bp + 1);
170                         src_c = *(ax25_address *)(bp + 8);
171 
172                         skb_pull(ourskb, AX25_HEADER_LEN - 1);  /* Keep PID */
173                         skb_reset_network_header(ourskb);
174 
175                         ax25=ax25_send_frame(
176                             ourskb,
177                             ax25_dev->values[AX25_VALUES_PACLEN],
178                             &src_c,
179                             &dst_c, digipeat, dev);
180                         if (ax25) {
181                                 ax25_cb_put(ax25);
182                         }
183                         goto put;
184                 }
185         }
186 
187         bp[7]  &= ~AX25_CBIT;
188         bp[7]  &= ~AX25_EBIT;
189         bp[7]  |= AX25_SSSID_SPARE;
190 
191         bp[14] &= ~AX25_CBIT;
192         bp[14] |= AX25_EBIT;
193         bp[14] |= AX25_SSSID_SPARE;
194 
195         skb_pull(skb, AX25_KISS_HEADER_LEN);
196 
197         if (digipeat != NULL) {
198                 if ((ourskb = ax25_rt_build_path(skb, src, dst, route->digipeat)) == NULL) {
199                         kfree_skb(skb);
200                         goto put;
201                 }
202 
203                 skb = ourskb;
204         }
205 
206         ax25_queue_xmit(skb, dev);
207 
208 put:
209         if (route)
210                 ax25_put_route(route);
211 
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);
252 
253 

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