1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 *
4 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
5 */
6 #include <linux/errno.h>
7 #include <linux/types.h>
8 #include <linux/socket.h>
9 #include <linux/in.h>
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/timer.h>
13 #include <linux/string.h>
14 #include <linux/sockios.h>
15 #include <linux/net.h>
16 #include <linux/slab.h>
17 #include <net/ax25.h>
18 #include <linux/inet.h>
19 #include <linux/netdevice.h>
20 #include <linux/if_arp.h>
21 #include <linux/skbuff.h>
22 #include <net/sock.h>
23 #include <linux/uaccess.h>
24 #include <linux/fcntl.h>
25 #include <linux/termios.h> /* For TIOCINQ/OUTQ */
26 #include <linux/mm.h>
27 #include <linux/interrupt.h>
28 #include <linux/notifier.h>
29 #include <linux/proc_fs.h>
30 #include <linux/stat.h>
31 #include <linux/sysctl.h>
32 #include <net/ip.h>
33 #include <net/arp.h>
34
35 /*
36 * IP over AX.25 encapsulation.
37 */
38
39 /*
40 * Shove an AX.25 UI header on an IP packet and handle ARP
41 */
42
43 #ifdef CONFIG_INET
44
45 static int ax25_hard_header(struct sk_buff *skb, struct net_device *dev,
46 unsigned short type, const void *daddr,
47 const void *saddr, unsigned int len)
48 {
49 unsigned char *buff;
50
51 /* they sometimes come back to us... */
52 if (type == ETH_P_AX25)
53 return 0;
54
55 /* header is an AX.25 UI frame from us to them */
56 buff = skb_push(skb, AX25_HEADER_LEN);
57 *buff++ = 0x00; /* KISS DATA */
58
59 if (daddr != NULL)
60 memcpy(buff, daddr, dev->addr_len); /* Address specified */
61
62 buff[6] &= ~AX25_CBIT;
63 buff[6] &= ~AX25_EBIT;
64 buff[6] |= AX25_SSSID_SPARE;
65 buff += AX25_ADDR_LEN;
66
67 if (saddr != NULL)
68 memcpy(buff, saddr, dev->addr_len);
69 else
70 memcpy(buff, dev->dev_addr, dev->addr_len);
71
72 buff[6] &= ~AX25_CBIT;
73 buff[6] |= AX25_EBIT;
74 buff[6] |= AX25_SSSID_SPARE;
75 buff += AX25_ADDR_LEN;
76
77 *buff++ = AX25_UI; /* UI */
78
79 /* Append a suitable AX.25 PID */
80 switch (type) {
81 case ETH_P_IP:
82 *buff++ = AX25_P_IP;
83 break;
84 case ETH_P_ARP:
85 *buff++ = AX25_P_ARP;
86 break;
87 default:
88 printk(KERN_ERR "AX.25: ax25_hard_header - wrong protocol type 0x%2.2x\n", type);
89 *buff++ = 0;
90 break;
91 }
92
93 if (daddr != NULL)
94 return AX25_HEADER_LEN;
95
96 return -AX25_HEADER_LEN; /* Unfinished header */
97 }
98
99 netdev_tx_t ax25_ip_xmit(struct sk_buff *skb)
100 {
101 struct sk_buff *ourskb;
102 unsigned char *bp = skb->data;
103 ax25_route *route;
104 struct net_device *dev = NULL;
105 ax25_address *src, *dst;
106 ax25_digi *digipeat = NULL;
107 ax25_dev *ax25_dev;
108 ax25_cb *ax25;
109 char ip_mode = ' ';
110
111 dst = (ax25_address *)(bp + 1);
112 src = (ax25_address *)(bp + 8);
113
114 ax25_route_lock_use();
115 route = ax25_get_route(dst, NULL);
116 if (route) {
117 digipeat = route->digipeat;
118 dev = route->dev;
119 ip_mode = route->ip_mode;
120 }
121
122 if (dev == NULL)
123 dev = skb->dev;
124
125 if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) {
126 kfree_skb(skb);
127 goto put;
128 }
129
130 if (bp[16] == AX25_P_IP) {
131 if (ip_mode == 'V' || (ip_mode == ' ' && ax25_dev->values[AX25_VALUES_IPDEFMODE])) {
132 /*
133 * We copy the buffer and release the original thereby
134 * keeping it straight
135 *
136 * Note: we report 1 back so the caller will
137 * not feed the frame direct to the physical device
138 * We don't want that to happen. (It won't be upset
139 * as we have pulled the frame from the queue by
140 * freeing it).
141 *
142 * NB: TCP modifies buffers that are still
143 * on a device queue, thus we use skb_copy()
144 * instead of using skb_clone() unless this
145 * gets fixed.
146 */
147
148 ax25_address src_c;
149 ax25_address dst_c;
150
151 if ((ourskb = skb_copy(skb, GFP_ATOMIC)) == NULL) {
152 kfree_skb(skb);
153 goto put;
154 }
155
156 if (skb->sk != NULL)
157 skb_set_owner_w(ourskb, skb->sk);
158
159 kfree_skb(skb);
160 /* dl9sau: bugfix
161 * after kfree_skb(), dst and src which were pointer
162 * to bp which is part of skb->data would not be valid
163 * anymore hope that after skb_pull(ourskb, ..) our
164 * dsc_c and src_c will not become invalid
165 */
166 bp = ourskb->data;
167 dst_c = *(ax25_address *)(bp + 1);
168 src_c = *(ax25_address *)(bp + 8);
169
170 skb_pull(ourskb, AX25_HEADER_LEN - 1); /* Keep PID */
171 skb_reset_network_header(ourskb);
172
173 ax25=ax25_send_frame(
174 ourskb,
175 ax25_dev->values[AX25_VALUES_PACLEN],
176 &src_c,
177 &dst_c, digipeat, dev);
178 if (ax25) {
179 ax25_cb_put(ax25);
180 }
181 goto put;
182 }
183 }
184
185 bp[7] &= ~AX25_CBIT;
186 bp[7] &= ~AX25_EBIT;
187 bp[7] |= AX25_SSSID_SPARE;
188
189 bp[14] &= ~AX25_CBIT;
190 bp[14] |= AX25_EBIT;
191 bp[14] |= AX25_SSSID_SPARE;
192
193 skb_pull(skb, AX25_KISS_HEADER_LEN);
194
195 if (digipeat != NULL) {
196 if ((ourskb = ax25_rt_build_path(skb, src, dst, route->digipeat)) == NULL)
197 goto put;
198
199 skb = ourskb;
200 }
201
202 ax25_queue_xmit(skb, dev);
203
204 put:
205
206 ax25_route_lock_unuse();
207 return NETDEV_TX_OK;
208 }
209
210 #else /* INET */
211
212 static int ax25_hard_header(struct sk_buff *skb, struct net_device *dev,
213 unsigned short type, const void *daddr,
214 const void *saddr, unsigned int len)
215 {
216 return -AX25_HEADER_LEN;
217 }
218
219 netdev_tx_t ax25_ip_xmit(struct sk_buff *skb)
220 {
221 kfree_skb(skb);
222 return NETDEV_TX_OK;
223 }
224 #endif
225
226 static bool ax25_validate_header(const char *header, unsigned int len)
227 {
228 ax25_digi digi;
229
230 if (!len)
231 return false;
232
233 if (header[0])
234 return true;
235
236 return ax25_addr_parse(header + 1, len - 1, NULL, NULL, &digi, NULL,
237 NULL);
238 }
239
240 const struct header_ops ax25_header_ops = {
241 .create = ax25_hard_header,
242 .validate = ax25_validate_header,
243 };
244
245 EXPORT_SYMBOL(ax25_header_ops);
246 EXPORT_SYMBOL(ax25_ip_xmit);
247
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