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 <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
ax25_hard_header(struct sk_buff * skb,struct net_device * dev,unsigned short type,const void * daddr,const void * saddr,unsigned len)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
ax25_rebuild_header(struct sk_buff * skb)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
ax25_hard_header(struct sk_buff * skb,struct net_device * dev,unsigned short type,const void * daddr,const void * saddr,unsigned len)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
ax25_rebuild_header(struct sk_buff * skb)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
243