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 <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, 51 unsigned short type, const void *daddr, 52 const void *saddr, unsigned len) 53 { 54 unsigned char *buff; 55 56 /* they sometimes come back to us... */ 57 if (type == ETH_P_AX25) 58 return 0; 59 60 /* header is an AX.25 UI frame from us to them */ 61 buff = skb_push(skb, AX25_HEADER_LEN); 62 *buff++ = 0x00; /* KISS DATA */ 63 64 if (daddr != NULL) 65 memcpy(buff, daddr, dev->addr_len); /* Address specified */ 66 67 buff[6] &= ~AX25_CBIT; 68 buff[6] &= ~AX25_EBIT; 69 buff[6] |= AX25_SSSID_SPARE; 70 buff += AX25_ADDR_LEN; 71 72 if (saddr != NULL) 73 memcpy(buff, saddr, dev->addr_len); 74 else 75 memcpy(buff, dev->dev_addr, dev->addr_len); 76 77 buff[6] &= ~AX25_CBIT; 78 buff[6] |= AX25_EBIT; 79 buff[6] |= AX25_SSSID_SPARE; 80 buff += AX25_ADDR_LEN; 81 82 *buff++ = AX25_UI; /* UI */ 83 84 /* Append a suitable AX.25 PID */ 85 switch (type) { 86 case ETH_P_IP: 87 *buff++ = AX25_P_IP; 88 break; 89 case ETH_P_ARP: 90 *buff++ = AX25_P_ARP; 91 break; 92 default: 93 printk(KERN_ERR "AX.25: ax25_hard_header - wrong protocol type 0x%2.2x\n", type); 94 *buff++ = 0; 95 break; 96 } 97 98 if (daddr != NULL) 99 return AX25_HEADER_LEN; 100 101 return -AX25_HEADER_LEN; /* Unfinished header */ 102 } 103 104 int ax25_rebuild_header(struct sk_buff *skb) 105 { 106 struct sk_buff *ourskb; 107 unsigned char *bp = skb->data; 108 ax25_route *route; 109 struct net_device *dev = NULL; 110 ax25_address *src, *dst; 111 ax25_digi *digipeat = NULL; 112 ax25_dev *ax25_dev; 113 ax25_cb *ax25; 114 char ip_mode = ' '; 115 116 dst = (ax25_address *)(bp + 1); 117 src = (ax25_address *)(bp + 8); 118 119 if (arp_find(bp + 1, skb)) 120 return 1; 121 122 route = ax25_get_route(dst, NULL); 123 if (route) { 124 digipeat = route->digipeat; 125 dev = route->dev; 126 ip_mode = route->ip_mode; 127 } 128 129 if (dev == NULL) 130 dev = skb->dev; 131 132 if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) { 133 goto put; 134 } 135 136 if (bp[16] == AX25_P_IP) { 137 if (ip_mode == 'V' || (ip_mode == ' ' && ax25_dev->values[AX25_VALUES_IPDEFMODE])) { 138 /* 139 * We copy the buffer and release the original thereby 140 * keeping it straight 141 * 142 * Note: we report 1 back so the caller will 143 * not feed the frame direct to the physical device 144 * We don't want that to happen. (It won't be upset 145 * as we have pulled the frame from the queue by 146 * freeing it). 147 * 148 * NB: TCP modifies buffers that are still 149 * on a device queue, thus we use skb_copy() 150 * instead of using skb_clone() unless this 151 * gets fixed. 152 */ 153 154 ax25_address src_c; 155 ax25_address dst_c; 156 157 if ((ourskb = skb_copy(skb, GFP_ATOMIC)) == NULL) { 158 kfree_skb(skb); 159 goto put; 160 } 161 162 if (skb->sk != NULL) 163 skb_set_owner_w(ourskb, skb->sk); 164 165 kfree_skb(skb); 166 /* dl9sau: bugfix 167 * after kfree_skb(), dst and src which were pointer 168 * to bp which is part of skb->data would not be valid 169 * anymore hope that after skb_pull(ourskb, ..) our 170 * dsc_c and src_c will not become invalid 171 */ 172 bp = ourskb->data; 173 dst_c = *(ax25_address *)(bp + 1); 174 src_c = *(ax25_address *)(bp + 8); 175 176 skb_pull(ourskb, AX25_HEADER_LEN - 1); /* Keep PID */ 177 skb_reset_network_header(ourskb); 178 179 ax25=ax25_send_frame( 180 ourskb, 181 ax25_dev->values[AX25_VALUES_PACLEN], 182 &src_c, 183 &dst_c, digipeat, dev); 184 if (ax25) { 185 ax25_cb_put(ax25); 186 } 187 goto put; 188 } 189 } 190 191 bp[7] &= ~AX25_CBIT; 192 bp[7] &= ~AX25_EBIT; 193 bp[7] |= AX25_SSSID_SPARE; 194 195 bp[14] &= ~AX25_CBIT; 196 bp[14] |= AX25_EBIT; 197 bp[14] |= AX25_SSSID_SPARE; 198 199 skb_pull(skb, AX25_KISS_HEADER_LEN); 200 201 if (digipeat != NULL) { 202 if ((ourskb = ax25_rt_build_path(skb, src, dst, route->digipeat)) == NULL) { 203 kfree_skb(skb); 204 goto put; 205 } 206 207 skb = ourskb; 208 } 209 210 ax25_queue_xmit(skb, dev); 211 212 put: 213 if (route) 214 ax25_put_route(route); 215 216 return 1; 217 } 218 219 #else /* INET */ 220 221 int ax25_hard_header(struct sk_buff *skb, struct net_device *dev, 222 unsigned short type, const void *daddr, 223 const void *saddr, unsigned len) 224 { 225 return -AX25_HEADER_LEN; 226 } 227 228 int ax25_rebuild_header(struct sk_buff *skb) 229 { 230 return 1; 231 } 232 233 #endif 234 235 const struct header_ops ax25_header_ops = { 236 .create = ax25_hard_header, 237 .rebuild = ax25_rebuild_header, 238 }; 239 240 EXPORT_SYMBOL(ax25_hard_header); 241 EXPORT_SYMBOL(ax25_rebuild_header); 242 EXPORT_SYMBOL(ax25_header_ops); 243 244