xref: /openbmc/linux/net/ax25/ax25_ip.c (revision 22246614)
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 <net/ax25.h>
20 #include <linux/inet.h>
21 #include <linux/netdevice.h>
22 #include <linux/if_arp.h>
23 #include <linux/skbuff.h>
24 #include <net/sock.h>
25 #include <asm/uaccess.h>
26 #include <asm/system.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 
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 
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 
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 
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