net/ethernet/eth.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              Ethernet-type device handling.
   7  *
   8  * Version:     @(#)eth.c       1.0.7   05/25/93
   9  *
  10  * Authors:     Ross Biro
  11  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  12  *              Mark Evans, <evansmp@uhura.aston.ac.uk>
  13  *              Florian  La Roche, <rzsfl@rz.uni-sb.de>
  14  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  15  *
  16  * Fixes:
  17  *              Mr Linux        : Arp problems
  18  *              Alan Cox        : Generic queue tidyup (very tiny here)
  19  *              Alan Cox        : eth_header ntohs should be htons
  20  *              Alan Cox        : eth_rebuild_header missing an htons and
  21  *                                minor other things.
  22  *              Tegge           : Arp bug fixes.
  23  *              Florian         : Removed many unnecessary functions, code cleanup
  24  *                                and changes for new arp and skbuff.
  25  *              Alan Cox        : Redid header building to reflect new format.
  26  *              Alan Cox        : ARP only when compiled with CONFIG_INET
  27  *              Greg Page       : 802.2 and SNAP stuff.
  28  *              Alan Cox        : MAC layer pointers/new format.
  29  *              Paul Gortmaker  : eth_copy_and_sum shouldn't csum padding.
  30  *              Alan Cox        : Protect against forwarding explosions with
  31  *                                older network drivers and IFF_ALLMULTI.
  32  *      Christer Weinigel       : Better rebuild header message.
  33  *             Andrew Morton    : 26Feb01: kill ether_setup() - use netdev_boot_setup().
  34  *
  35  *              This program is free software; you can redistribute it and/or
  36  *              modify it under the terms of the GNU General Public License
  37  *              as published by the Free Software Foundation; either version
  38  *              2 of the License, or (at your option) any later version.
  39  */
  40 #include <linux/module.h>
  41 #include <linux/types.h>
  42 #include <linux/kernel.h>
  43 #include <linux/sched.h>
  44 #include <linux/string.h>
  45 #include <linux/mm.h>
  46 #include <linux/socket.h>
  47 #include <linux/in.h>
  48 #include <linux/inet.h>
  49 #include <linux/ip.h>
  50 #include <linux/netdevice.h>
  51 #include <linux/etherdevice.h>
  52 #include <linux/skbuff.h>
  53 #include <linux/errno.h>
  54 #include <linux/config.h>
  55 #include <linux/init.h>
  56 #include <net/dst.h>
  57 #include <net/arp.h>
  58 #include <net/sock.h>
  59 #include <net/ipv6.h>
  60 #include <net/ip.h>
  61 #include <asm/uaccess.h>
  62 #include <asm/system.h>
  63 #include <asm/checksum.h>
  64
  65 extern int __init netdev_boot_setup(char *str);
  66
  67 __setup("ether=", netdev_boot_setup);
  68
  69 /*
  70  *       Create the Ethernet MAC header for an arbitrary protocol layer
  71  *
  72  *      saddr=NULL      means use device source address
  73  *      daddr=NULL      means leave destination address (eg unresolved arp)
  74  */
  75
  76 int eth_header(struct sk_buff *skb, struct net_device *dev, unsigned short type,
  77            void *daddr, void *saddr, unsigned len)
  78 {
  79         struct ethhdr *eth = (struct ethhdr *)skb_push(skb,ETH_HLEN);
  80
  81         /*
  82          *      Set the protocol type. For a packet of type ETH_P_802_3 we put the length
  83          *      in here instead. It is up to the 802.2 layer to carry protocol information.
  84          */
  85
  86         if(type!=ETH_P_802_3)
  87                 eth->h_proto = htons(type);
  88         else
  89                 eth->h_proto = htons(len);
  90
  91         /*
  92          *      Set the source hardware address.
  93          */
  94
  95         if(!saddr)
  96                 saddr = dev->dev_addr;
  97         memcpy(eth->h_source,saddr,dev->addr_len);
  98
  99         /*
 100          *      Anyway, the loopback-device should never use this function...
 101          */
 102
 103         if (dev->flags & (IFF_LOOPBACK|IFF_NOARP))
 104         {
 105                 memset(eth->h_dest, 0, dev->addr_len);
 106                 return ETH_HLEN;
 107         }
 108
 109         if(daddr)
 110         {
 111                 memcpy(eth->h_dest,daddr,dev->addr_len);
 112                 return ETH_HLEN;
 113         }
 114
 115         return -ETH_HLEN;
 116 }
 117
 118
 119 /*
 120  *      Rebuild the Ethernet MAC header. This is called after an ARP
 121  *      (or in future other address resolution) has completed on this
 122  *      sk_buff. We now let ARP fill in the other fields.
 123  *
 124  *      This routine CANNOT use cached dst->neigh!
 125  *      Really, it is used only when dst->neigh is wrong.
 126  */
 127
 128 int eth_rebuild_header(struct sk_buff *skb)
 129 {
 130         struct ethhdr *eth = (struct ethhdr *)skb->data;
 131         struct net_device *dev = skb->dev;
 132
 133         switch (eth->h_proto)
 134         {
 135 #ifdef CONFIG_INET
 136         case __constant_htons(ETH_P_IP):
 137                 return arp_find(eth->h_dest, skb);
 138 #endif
 139         default:
 140                 printk(KERN_DEBUG
 141                        "%s: unable to resolve type %X addresses.\n",
 142                        dev->name, (int)eth->h_proto);
 143
 144                 memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
 145                 break;
 146         }
 147
 148         return 0;
 149 }
 150
 151
 152 /*
 153  *      Determine the packet's protocol ID. The rule here is that we
 154  *      assume 802.3 if the type field is short enough to be a length.
 155  *      This is normal practice and works for any 'now in use' protocol.
 156  */
 157
 158 __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
 159 {
 160         struct ethhdr *eth;
 161         unsigned char *rawp;
 162
 163         skb->mac.raw=skb->data;
 164         skb_pull(skb,ETH_HLEN);
 165         eth = eth_hdr(skb);
 166         skb->input_dev = dev;
 167
 168         if(*eth->h_dest&1)
 169         {
 170                 if(memcmp(eth->h_dest,dev->broadcast, ETH_ALEN)==0)
 171                         skb->pkt_type=PACKET_BROADCAST;
 172                 else
 173                         skb->pkt_type=PACKET_MULTICAST;
 174         }
 175
 176         /*
 177          *      This ALLMULTI check should be redundant by 1.4
 178          *      so don't forget to remove it.
 179          *
 180          *      Seems, you forgot to remove it. All silly devices
 181          *      seems to set IFF_PROMISC.
 182          */
 183
 184         else if(1 /*dev->flags&IFF_PROMISC*/)
 185         {
 186                 if(memcmp(eth->h_dest,dev->dev_addr, ETH_ALEN))
 187                         skb->pkt_type=PACKET_OTHERHOST;
 188         }
 189
 190         if (ntohs(eth->h_proto) >= 1536)
 191                 return eth->h_proto;
 192
 193         rawp = skb->data;
 194
 195         /*
 196          *      This is a magic hack to spot IPX packets. Older Novell breaks
 197          *      the protocol design and runs IPX over 802.3 without an 802.2 LLC
 198          *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
 199          *      won't work for fault tolerant netware but does for the rest.
 200          */
 201         if (*(unsigned short *)rawp == 0xFFFF)
 202                 return htons(ETH_P_802_3);
 203
 204         /*
 205          *      Real 802.2 LLC
 206          */
 207         return htons(ETH_P_802_2);
 208 }
 209
 210 static int eth_header_parse(struct sk_buff *skb, unsigned char *haddr)
 211 {
 212         struct ethhdr *eth = eth_hdr(skb);
 213         memcpy(haddr, eth->h_source, ETH_ALEN);
 214         return ETH_ALEN;
 215 }
 216
 217 int eth_header_cache(struct neighbour *neigh, struct hh_cache *hh)
 218 {
 219         unsigned short type = hh->hh_type;
 220         struct ethhdr *eth;
 221         struct net_device *dev = neigh->dev;
 222
 223         eth = (struct ethhdr*)
 224                 (((u8*)hh->hh_data) + (HH_DATA_OFF(sizeof(*eth))));
 225
 226         if (type == __constant_htons(ETH_P_802_3))
 227                 return -1;
 228
 229         eth->h_proto = type;
 230         memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
 231         memcpy(eth->h_dest, neigh->ha, dev->addr_len);
 232         hh->hh_len = ETH_HLEN;
 233         return 0;
 234 }
 235
 236 /*
 237  * Called by Address Resolution module to notify changes in address.
 238  */
 239
 240 void eth_header_cache_update(struct hh_cache *hh, struct net_device *dev, unsigned char * haddr)
 241 {
 242         memcpy(((u8*)hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)),
 243                haddr, dev->addr_len);
 244 }
 245
 246 EXPORT_SYMBOL(eth_type_trans);
 247
 248 static int eth_mac_addr(struct net_device *dev, void *p)
 249 {
 250         struct sockaddr *addr=p;
 251         if (netif_running(dev))
 252                 return -EBUSY;
 253         memcpy(dev->dev_addr, addr->sa_data,dev->addr_len);
 254         return 0;
 255 }
 256
 257 static int eth_change_mtu(struct net_device *dev, int new_mtu)
 258 {
 259         if ((new_mtu < 68) || (new_mtu > 1500))
 260                 return -EINVAL;
 261         dev->mtu = new_mtu;
 262         return 0;
 263 }
 264
 265 /*
 266  * Fill in the fields of the device structure with ethernet-generic values.
 267  */
 268 void ether_setup(struct net_device *dev)
 269 {
 270         dev->change_mtu         = eth_change_mtu;
 271         dev->hard_header        = eth_header;
 272         dev->rebuild_header     = eth_rebuild_header;
 273         dev->set_mac_address    = eth_mac_addr;
 274         dev->hard_header_cache  = eth_header_cache;
 275         dev->header_cache_update= eth_header_cache_update;
 276         dev->hard_header_parse  = eth_header_parse;
 277
 278         dev->type               = ARPHRD_ETHER;
 279         dev->hard_header_len    = ETH_HLEN;
 280         dev->mtu                = 1500; /* eth_mtu */
 281         dev->addr_len           = ETH_ALEN;
 282         dev->tx_queue_len       = 1000; /* Ethernet wants good queues */
 283         dev->flags              = IFF_BROADCAST|IFF_MULTICAST;
 284
 285         memset(dev->broadcast,0xFF, ETH_ALEN);
 286
 287 }
 288 EXPORT_SYMBOL(ether_setup);
 289
 290 /**
 291  * alloc_etherdev - Allocates and sets up an ethernet device
 292  * @sizeof_priv: Size of additional driver-private structure to be allocated
 293  *      for this ethernet device
 294  *
 295  * Fill in the fields of the device structure with ethernet-generic
 296  * values. Basically does everything except registering the device.
 297  *
 298  * Constructs a new net device, complete with a private data area of
 299  * size @sizeof_priv.  A 32-byte (not bit) alignment is enforced for
 300  * this private data area.
 301  */
 302
 303 struct net_device *alloc_etherdev(int sizeof_priv)
 304 {
 305         return alloc_netdev(sizeof_priv, "eth%d", ether_setup);
 306 }
 307 EXPORT_SYMBOL(alloc_etherdev);