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 rcu_read_lock(); 126 if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) { 127 kfree_skb(skb); 128 goto put; 129 } 130 131 if (bp[16] == AX25_P_IP) { 132 if (ip_mode == 'V' || (ip_mode == ' ' && ax25_dev->values[AX25_VALUES_IPDEFMODE])) { 133 /* 134 * We copy the buffer and release the original thereby 135 * keeping it straight 136 * 137 * Note: we report 1 back so the caller will 138 * not feed the frame direct to the physical device 139 * We don't want that to happen. (It won't be upset 140 * as we have pulled the frame from the queue by 141 * freeing it). 142 * 143 * NB: TCP modifies buffers that are still 144 * on a device queue, thus we use skb_copy() 145 * instead of using skb_clone() unless this 146 * gets fixed. 147 */ 148 149 ax25_address src_c; 150 ax25_address dst_c; 151 152 if ((ourskb = skb_copy(skb, GFP_ATOMIC)) == NULL) { 153 kfree_skb(skb); 154 goto put; 155 } 156 157 if (skb->sk != NULL) 158 skb_set_owner_w(ourskb, skb->sk); 159 160 kfree_skb(skb); 161 /* dl9sau: bugfix 162 * after kfree_skb(), dst and src which were pointer 163 * to bp which is part of skb->data would not be valid 164 * anymore hope that after skb_pull(ourskb, ..) our 165 * dsc_c and src_c will not become invalid 166 */ 167 bp = ourskb->data; 168 dst_c = *(ax25_address *)(bp + 1); 169 src_c = *(ax25_address *)(bp + 8); 170 171 skb_pull(ourskb, AX25_HEADER_LEN - 1); /* Keep PID */ 172 skb_reset_network_header(ourskb); 173 174 ax25=ax25_send_frame( 175 ourskb, 176 ax25_dev->values[AX25_VALUES_PACLEN], 177 &src_c, 178 &dst_c, digipeat, dev); 179 if (ax25) { 180 ax25_cb_put(ax25); 181 } 182 goto put; 183 } 184 } 185 186 bp[7] &= ~AX25_CBIT; 187 bp[7] &= ~AX25_EBIT; 188 bp[7] |= AX25_SSSID_SPARE; 189 190 bp[14] &= ~AX25_CBIT; 191 bp[14] |= AX25_EBIT; 192 bp[14] |= AX25_SSSID_SPARE; 193 194 skb_pull(skb, AX25_KISS_HEADER_LEN); 195 196 if (digipeat != NULL) { 197 if ((ourskb = ax25_rt_build_path(skb, src, dst, route->digipeat)) == NULL) 198 goto put; 199 200 skb = ourskb; 201 } 202 203 ax25_queue_xmit(skb, dev); 204 205 put: 206 rcu_read_unlock(); 207 ax25_route_lock_unuse(); 208 return NETDEV_TX_OK; 209 } 210 211 #else /* INET */ 212 213 static int ax25_hard_header(struct sk_buff *skb, struct net_device *dev, 214 unsigned short type, const void *daddr, 215 const void *saddr, unsigned int len) 216 { 217 return -AX25_HEADER_LEN; 218 } 219 220 netdev_tx_t ax25_ip_xmit(struct sk_buff *skb) 221 { 222 kfree_skb(skb); 223 return NETDEV_TX_OK; 224 } 225 #endif 226 227 static bool ax25_validate_header(const char *header, unsigned int len) 228 { 229 ax25_digi digi; 230 231 if (!len) 232 return false; 233 234 if (header[0]) 235 return true; 236 237 return ax25_addr_parse(header + 1, len - 1, NULL, NULL, &digi, NULL, 238 NULL); 239 } 240 241 const struct header_ops ax25_header_ops = { 242 .create = ax25_hard_header, 243 .validate = ax25_validate_header, 244 }; 245 246 EXPORT_SYMBOL(ax25_header_ops); 247 EXPORT_SYMBOL(ax25_ip_xmit); 248