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