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 __setup("ether=", netdev_boot_setup);
  66
  67 /*
  68  *       Create the Ethernet MAC header for an arbitrary protocol layer
  69  *
  70  *      saddr=NULL      means use device source address
  71  *      daddr=NULL      means leave destination address (eg unresolved arp)
  72  */
  73
  74 int eth_header(struct sk_buff *skb, struct net_device *dev, unsigned short type,
  75            void *daddr, void *saddr, unsigned len)
  76 {
  77         struct ethhdr *eth = (struct ethhdr *)skb_push(skb,ETH_HLEN);
  78
  79         /*
  80          *      Set the protocol type. For a packet of type ETH_P_802_3 we put the length
  81          *      in here instead. It is up to the 802.2 layer to carry protocol information.
  82          */
  83
  84         if(type!=ETH_P_802_3)
  85                 eth->h_proto = htons(type);
  86         else
  87                 eth->h_proto = htons(len);
  88
  89         /*
  90          *      Set the source hardware address.
  91          */
  92
  93         if(!saddr)
  94                 saddr = dev->dev_addr;
  95         memcpy(eth->h_source,saddr,dev->addr_len);
  96
  97         /*
  98          *      Anyway, the loopback-device should never use this function...
  99          */
 100
 101         if (dev->flags & (IFF_LOOPBACK|IFF_NOARP))
 102         {
 103                 memset(eth->h_dest, 0, dev->addr_len);
 104                 return ETH_HLEN;
 105         }
 106
 107         if(daddr)
 108         {
 109                 memcpy(eth->h_dest,daddr,dev->addr_len);
 110                 return ETH_HLEN;
 111         }
 112
 113         return -ETH_HLEN;
 114 }
 115
 116
 117 /*
 118  *      Rebuild the Ethernet MAC header. This is called after an ARP
 119  *      (or in future other address resolution) has completed on this
 120  *      sk_buff. We now let ARP fill in the other fields.
 121  *
 122  *      This routine CANNOT use cached dst->neigh!
 123  *      Really, it is used only when dst->neigh is wrong.
 124  */
 125
 126 int eth_rebuild_header(struct sk_buff *skb)
 127 {
 128         struct ethhdr *eth = (struct ethhdr *)skb->data;
 129         struct net_device *dev = skb->dev;
 130
 131         switch (eth->h_proto)
 132         {
 133 #ifdef CONFIG_INET
 134         case __constant_htons(ETH_P_IP):
 135                 return arp_find(eth->h_dest, skb);
 136 #endif
 137         default:
 138                 printk(KERN_DEBUG
 139                        "%s: unable to resolve type %X addresses.\n",
 140                        dev->name, (int)eth->h_proto);
 141
 142                 memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
 143                 break;
 144         }
 145
 146         return 0;
 147 }
 148
 149 static inline unsigned int compare_eth_addr(const unsigned char *__a, const unsigned char *__b)
 150 {
 151         const unsigned short *dest = (unsigned short *) __a;
 152         const unsigned short *devaddr = (unsigned short *) __b;
 153         unsigned int res;
 154
 155         BUILD_BUG_ON(ETH_ALEN != 6);
 156         res = ((dest[0] ^ devaddr[0]) |
 157                (dest[1] ^ devaddr[1]) |
 158                (dest[2] ^ devaddr[2])) != 0;
 159
 160         return res;
 161 }
 162
 163 /*
 164  *      Determine the packet's protocol ID. The rule here is that we
 165  *      assume 802.3 if the type field is short enough to be a length.
 166  *      This is normal practice and works for any 'now in use' protocol.
 167  */
 168
 169 __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
 170 {
 171         struct ethhdr *eth;
 172         unsigned char *rawp;
 173
 174         skb->mac.raw = skb->data;
 175         skb_pull(skb,ETH_HLEN);
 176         eth = eth_hdr(skb);
 177
 178         if (*eth->h_dest&1) {
 179                 if (!compare_eth_addr(eth->h_dest, dev->broadcast))
 180                         skb->pkt_type = PACKET_BROADCAST;
 181                 else
 182                         skb->pkt_type = PACKET_MULTICAST;
 183         }
 184
 185         /*
 186          *      This ALLMULTI check should be redundant by 1.4
 187          *      so don't forget to remove it.
 188          *
 189          *      Seems, you forgot to remove it. All silly devices
 190          *      seems to set IFF_PROMISC.
 191          */
 192
 193         else if(1 /*dev->flags&IFF_PROMISC*/) {
 194                 if (unlikely(compare_eth_addr(eth->h_dest, dev->dev_addr)))
 195                         skb->pkt_type = PACKET_OTHERHOST;
 196         }
 197
 198         if (ntohs(eth->h_proto) >= 1536)
 199                 return eth->h_proto;
 200
 201         rawp = skb->data;
 202
 203         /*
 204          *      This is a magic hack to spot IPX packets. Older Novell breaks
 205          *      the protocol design and runs IPX over 802.3 without an 802.2 LLC
 206          *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
 207          *      won't work for fault tolerant netware but does for the rest.
 208          */
 209         if (*(unsigned short *)rawp == 0xFFFF)
 210                 return htons(ETH_P_802_3);
 211
 212         /*
 213          *      Real 802.2 LLC
 214          */
 215         return htons(ETH_P_802_2);
 216 }
 217
 218 static int eth_header_parse(struct sk_buff *skb, unsigned char *haddr)
 219 {
 220         struct ethhdr *eth = eth_hdr(skb);
 221         memcpy(haddr, eth->h_source, ETH_ALEN);
 222         return ETH_ALEN;
 223 }
 224
 225 int eth_header_cache(struct neighbour *neigh, struct hh_cache *hh)
 226 {
 227         unsigned short type = hh->hh_type;
 228         struct ethhdr *eth;
 229         struct net_device *dev = neigh->dev;
 230
 231         eth = (struct ethhdr*)
 232                 (((u8*)hh->hh_data) + (HH_DATA_OFF(sizeof(*eth))));
 233
 234         if (type == __constant_htons(ETH_P_802_3))
 235                 return -1;
 236
 237         eth->h_proto = type;
 238         memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
 239         memcpy(eth->h_dest, neigh->ha, dev->addr_len);
 240         hh->hh_len = ETH_HLEN;
 241         return 0;
 242 }
 243
 244 /*
 245  * Called by Address Resolution module to notify changes in address.
 246  */
 247
 248 void eth_header_cache_update(struct hh_cache *hh, struct net_device *dev, unsigned char * haddr)
 249 {
 250         memcpy(((u8*)hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)),
 251                haddr, dev->addr_len);
 252 }
 253
 254 EXPORT_SYMBOL(eth_type_trans);
 255
 256 static int eth_mac_addr(struct net_device *dev, void *p)
 257 {
 258         struct sockaddr *addr=p;
 259         if (netif_running(dev))
 260                 return -EBUSY;
 261         memcpy(dev->dev_addr, addr->sa_data,dev->addr_len);
 262         return 0;
 263 }
 264
 265 static int eth_change_mtu(struct net_device *dev, int new_mtu)
 266 {
 267         if ((new_mtu < 68) || (new_mtu > 1500))
 268                 return -EINVAL;
 269         dev->mtu = new_mtu;
 270         return 0;
 271 }
 272
 273 /*
 274  * Fill in the fields of the device structure with ethernet-generic values.
 275  */
 276 void ether_setup(struct net_device *dev)
 277 {
 278         dev->change_mtu         = eth_change_mtu;
 279         dev->hard_header        = eth_header;
 280         dev->rebuild_header     = eth_rebuild_header;
 281         dev->set_mac_address    = eth_mac_addr;
 282         dev->hard_header_cache  = eth_header_cache;
 283         dev->header_cache_update= eth_header_cache_update;
 284         dev->hard_header_parse  = eth_header_parse;
 285
 286         dev->type               = ARPHRD_ETHER;
 287         dev->hard_header_len    = ETH_HLEN;
 288         dev->mtu                = 1500; /* eth_mtu */
 289         dev->addr_len           = ETH_ALEN;
 290         dev->tx_queue_len       = 1000; /* Ethernet wants good queues */
 291         dev->flags              = IFF_BROADCAST|IFF_MULTICAST;
 292
 293         memset(dev->broadcast,0xFF, ETH_ALEN);
 294
 295 }
 296 EXPORT_SYMBOL(ether_setup);
 297
 298 /**
 299  * alloc_etherdev - Allocates and sets up an ethernet device
 300  * @sizeof_priv: Size of additional driver-private structure to be allocated
 301  *      for this ethernet device
 302  *
 303  * Fill in the fields of the device structure with ethernet-generic
 304  * values. Basically does everything except registering the device.
 305  *
 306  * Constructs a new net device, complete with a private data area of
 307  * size @sizeof_priv.  A 32-byte (not bit) alignment is enforced for
 308  * this private data area.
 309  */
 310
 311 struct net_device *alloc_etherdev(int sizeof_priv)
 312 {
 313         return alloc_netdev(sizeof_priv, "eth%d", ether_setup);
 314 }
 315 EXPORT_SYMBOL(alloc_etherdev);