xref: /openbmc/linux/net/ax25/ax25_ip.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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/config.h>
10 #include <linux/errno.h>
11 #include <linux/types.h>
12 #include <linux/socket.h>
13 #include <linux/in.h>
14 #include <linux/kernel.h>
15 #include <linux/sched.h>
16 #include <linux/timer.h>
17 #include <linux/string.h>
18 #include <linux/sockios.h>
19 #include <linux/net.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, unsigned short type, void *daddr, void *saddr, unsigned 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 int ax25_rebuild_header(struct sk_buff *skb)
103 {
104 	struct sk_buff *ourskb;
105 	unsigned char *bp  = skb->data;
106 	struct net_device *dev;
107 	ax25_address *src, *dst;
108 	ax25_dev *ax25_dev;
109 	ax25_route _route, *route = &_route;
110 	ax25_cb *ax25;
111 
112 	dst = (ax25_address *)(bp + 1);
113 	src = (ax25_address *)(bp + 8);
114 
115   	if (arp_find(bp + 1, skb))
116   		return 1;
117 
118 	route = ax25_rt_find_route(route, dst, NULL);
119 	dev      = route->dev;
120 
121 	if (dev == NULL)
122 		dev = skb->dev;
123 
124         if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) {
125                 goto put;
126 	}
127 
128 	if (bp[16] == AX25_P_IP) {
129 		if (route->ip_mode == 'V' || (route->ip_mode == ' ' && ax25_dev->values[AX25_VALUES_IPDEFMODE])) {
130 			/*
131 			 *	We copy the buffer and release the original thereby
132 			 *	keeping it straight
133 			 *
134 			 *	Note: we report 1 back so the caller will
135 			 *	not feed the frame direct to the physical device
136 			 *	We don't want that to happen. (It won't be upset
137 			 *	as we have pulled the frame from the queue by
138 			 *	freeing it).
139 			 *
140 			 *	NB: TCP modifies buffers that are still
141 			 *	on a device queue, thus we use skb_copy()
142 			 *      instead of using skb_clone() unless this
143 			 *	gets fixed.
144 			 */
145 
146 			ax25_address src_c;
147 			ax25_address dst_c;
148 
149 			if ((ourskb = skb_copy(skb, GFP_ATOMIC)) == NULL) {
150 				kfree_skb(skb);
151 				goto put;
152 			}
153 
154 			if (skb->sk != NULL)
155 				skb_set_owner_w(ourskb, skb->sk);
156 
157 			kfree_skb(skb);
158 			/* dl9sau: bugfix
159 			 * after kfree_skb(), dst and src which were pointer
160 			 * to bp which is part of skb->data would not be valid
161 			 * anymore hope that after skb_pull(ourskb, ..) our
162 			 * dsc_c and src_c will not become invalid
163 			 */
164 			bp  = ourskb->data;
165 			dst_c = *(ax25_address *)(bp + 1);
166 			src_c = *(ax25_address *)(bp + 8);
167 
168 			skb_pull(ourskb, AX25_HEADER_LEN - 1);	/* Keep PID */
169 			ourskb->nh.raw = ourskb->data;
170 
171 			ax25=ax25_send_frame(
172 			    ourskb,
173 			    ax25_dev->values[AX25_VALUES_PACLEN],
174 			    &src_c,
175 			    &dst_c, route->digipeat, dev);
176 			if (ax25) {
177 				ax25_cb_put(ax25);
178 			}
179 			goto put;
180 		}
181 	}
182 
183   	bp[7]  &= ~AX25_CBIT;
184   	bp[7]  &= ~AX25_EBIT;
185   	bp[7]  |= AX25_SSSID_SPARE;
186 
187   	bp[14] &= ~AX25_CBIT;
188   	bp[14] |= AX25_EBIT;
189   	bp[14] |= AX25_SSSID_SPARE;
190 
191 	skb_pull(skb, AX25_KISS_HEADER_LEN);
192 
193 	if (route->digipeat != NULL) {
194 		if ((ourskb = ax25_rt_build_path(skb, src, dst, route->digipeat)) == NULL) {
195 			kfree_skb(skb);
196 			goto put;
197 		}
198 
199 		skb = ourskb;
200 	}
201 
202 	ax25_queue_xmit(skb, dev);
203 
204 put:
205 	ax25_put_route(route);
206 
207   	return 1;
208 }
209 
210 #else	/* INET */
211 
212 int ax25_hard_header(struct sk_buff *skb, struct net_device *dev, unsigned short type, void *daddr, void *saddr, unsigned len)
213 {
214 	return -AX25_HEADER_LEN;
215 }
216 
217 int ax25_rebuild_header(struct sk_buff *skb)
218 {
219 	return 1;
220 }
221 
222 #endif
223 
224