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 <linux/if_ether.h>
  57 #include <net/dst.h>
  58 #include <net/arp.h>
  59 #include <net/sock.h>
  60 #include <net/ipv6.h>
  61 #include <net/ip.h>
  62 #include <asm/uaccess.h>
  63 #include <asm/system.h>
  64 #include <asm/checksum.h>
  65
  66 __setup("ether=", netdev_boot_setup);
  67
  68 /*
  69  *       Create the Ethernet MAC header for an arbitrary protocol layer
  70  *
  71  *      saddr=NULL      means use device source address
  72  *      daddr=NULL      means leave destination address (eg unresolved arp)
  73  */
  74
  75 int eth_header(struct sk_buff *skb, struct net_device *dev, unsigned short type,
  76            void *daddr, void *saddr, unsigned len)
  77 {
  78         struct ethhdr *eth = (struct ethhdr *)skb_push(skb,ETH_HLEN);
  79
  80         /*
  81          *      Set the protocol type. For a packet of type ETH_P_802_3 we put the length
  82          *      in here instead. It is up to the 802.2 layer to carry protocol information.
  83          */
  84
  85         if(type!=ETH_P_802_3)
  86                 eth->h_proto = htons(type);
  87         else
  88                 eth->h_proto = htons(len);
  89
  90         /*
  91          *      Set the source hardware address.
  92          */
  93
  94         if(!saddr)
  95                 saddr = dev->dev_addr;
  96         memcpy(eth->h_source,saddr,dev->addr_len);
  97
  98         if(daddr)
  99         {
 100                 memcpy(eth->h_dest,daddr,dev->addr_len);
 101                 return ETH_HLEN;
 102         }
 103
 104         /*
 105          *      Anyway, the loopback-device should never use this function...
 106          */
 107
 108         if (dev->flags & (IFF_LOOPBACK|IFF_NOARP))
 109         {
 110                 memset(eth->h_dest, 0, dev->addr_len);
 111                 return ETH_HLEN;
 112         }
 113
 114         return -ETH_HLEN;
 115 }
 116
 117
 118 /*
 119  *      Rebuild the Ethernet MAC header. This is called after an ARP
 120  *      (or in future other address resolution) has completed on this
 121  *      sk_buff. We now let ARP fill in the other fields.
 122  *
 123  *      This routine CANNOT use cached dst->neigh!
 124  *      Really, it is used only when dst->neigh is wrong.
 125  */
 126
 127 int eth_rebuild_header(struct sk_buff *skb)
 128 {
 129         struct ethhdr *eth = (struct ethhdr *)skb->data;
 130         struct net_device *dev = skb->dev;
 131
 132         switch (eth->h_proto)
 133         {
 134 #ifdef CONFIG_INET
 135         case __constant_htons(ETH_P_IP):
 136                 return arp_find(eth->h_dest, skb);
 137 #endif
 138         default:
 139                 printk(KERN_DEBUG
 140                        "%s: unable to resolve type %X addresses.\n",
 141                        dev->name, (int)eth->h_proto);
 142
 143                 memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
 144                 break;
 145         }
 146
 147         return 0;
 148 }
 149
 150
 151 /*
 152  *      Determine the packet's protocol ID. The rule here is that we
 153  *      assume 802.3 if the type field is short enough to be a length.
 154  *      This is normal practice and works for any 'now in use' protocol.
 155  */
 156
 157 __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
 158 {
 159         struct ethhdr *eth;
 160         unsigned char *rawp;
 161
 162         skb->mac.raw = skb->data;
 163         skb_pull(skb,ETH_HLEN);
 164         eth = eth_hdr(skb);
 165
 166         if (is_multicast_ether_addr(eth->h_dest)) {
 167                 if (!compare_ether_addr(eth->h_dest, dev->broadcast))
 168                         skb->pkt_type = PACKET_BROADCAST;
 169                 else
 170                         skb->pkt_type = PACKET_MULTICAST;
 171         }
 172
 173         /*
 174          *      This ALLMULTI check should be redundant by 1.4
 175          *      so don't forget to remove it.
 176          *
 177          *      Seems, you forgot to remove it. All silly devices
 178          *      seems to set IFF_PROMISC.
 179          */
 180
 181         else if(1 /*dev->flags&IFF_PROMISC*/) {
 182                 if (unlikely(compare_ether_addr(eth->h_dest, dev->dev_addr)))
 183                         skb->pkt_type = PACKET_OTHERHOST;
 184         }
 185
 186         if (ntohs(eth->h_proto) >= 1536)
 187                 return eth->h_proto;
 188
 189         rawp = skb->data;
 190
 191         /*
 192          *      This is a magic hack to spot IPX packets. Older Novell breaks
 193          *      the protocol design and runs IPX over 802.3 without an 802.2 LLC
 194          *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
 195          *      won't work for fault tolerant netware but does for the rest.
 196          */
 197         if (*(unsigned short *)rawp == 0xFFFF)
 198                 return htons(ETH_P_802_3);
 199
 200         /*
 201          *      Real 802.2 LLC
 202          */
 203         return htons(ETH_P_802_2);
 204 }
 205
 206 static int eth_header_parse(struct sk_buff *skb, unsigned char *haddr)
 207 {
 208         struct ethhdr *eth = eth_hdr(skb);
 209         memcpy(haddr, eth->h_source, ETH_ALEN);
 210         return ETH_ALEN;
 211 }
 212
 213 int eth_header_cache(struct neighbour *neigh, struct hh_cache *hh)
 214 {
 215         unsigned short type = hh->hh_type;
 216         struct ethhdr *eth;
 217         struct net_device *dev = neigh->dev;
 218
 219         eth = (struct ethhdr*)
 220                 (((u8*)hh->hh_data) + (HH_DATA_OFF(sizeof(*eth))));
 221
 222         if (type == __constant_htons(ETH_P_802_3))
 223                 return -1;
 224
 225         eth->h_proto = type;
 226         memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
 227         memcpy(eth->h_dest, neigh->ha, dev->addr_len);
 228         hh->hh_len = ETH_HLEN;
 229         return 0;
 230 }
 231
 232 /*
 233  * Called by Address Resolution module to notify changes in address.
 234  */
 235
 236 void eth_header_cache_update(struct hh_cache *hh, struct net_device *dev, unsigned char * haddr)
 237 {
 238         memcpy(((u8*)hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)),
 239                haddr, dev->addr_len);
 240 }
 241
 242 EXPORT_SYMBOL(eth_type_trans);
 243
 244 static int eth_mac_addr(struct net_device *dev, void *p)
 245 {
 246         struct sockaddr *addr=p;
 247         if (netif_running(dev))
 248                 return -EBUSY;
 249         memcpy(dev->dev_addr, addr->sa_data,dev->addr_len);
 250         return 0;
 251 }
 252
 253 static int eth_change_mtu(struct net_device *dev, int new_mtu)
 254 {
 255         if (new_mtu < 68 || new_mtu > ETH_DATA_LEN)
 256                 return -EINVAL;
 257         dev->mtu = new_mtu;
 258         return 0;
 259 }
 260
 261 /*
 262  * Fill in the fields of the device structure with ethernet-generic values.
 263  */
 264 void ether_setup(struct net_device *dev)
 265 {
 266         dev->change_mtu         = eth_change_mtu;
 267         dev->hard_header        = eth_header;
 268         dev->rebuild_header     = eth_rebuild_header;
 269         dev->set_mac_address    = eth_mac_addr;
 270         dev->hard_header_cache  = eth_header_cache;
 271         dev->header_cache_update= eth_header_cache_update;
 272         dev->hard_header_parse  = eth_header_parse;
 273
 274         dev->type               = ARPHRD_ETHER;
 275         dev->hard_header_len    = ETH_HLEN;
 276         dev->mtu                = ETH_DATA_LEN;
 277         dev->addr_len           = ETH_ALEN;
 278         dev->tx_queue_len       = 1000; /* Ethernet wants good queues */
 279         dev->flags              = IFF_BROADCAST|IFF_MULTICAST;
 280
 281         memset(dev->broadcast,0xFF, ETH_ALEN);
 282
 283 }
 284 EXPORT_SYMBOL(ether_setup);
 285
 286 /**
 287  * alloc_etherdev - Allocates and sets up an ethernet device
 288  * @sizeof_priv: Size of additional driver-private structure to be allocated
 289  *      for this ethernet device
 290  *
 291  * Fill in the fields of the device structure with ethernet-generic
 292  * values. Basically does everything except registering the device.
 293  *
 294  * Constructs a new net device, complete with a private data area of
 295  * size @sizeof_priv.  A 32-byte (not bit) alignment is enforced for
 296  * this private data area.
 297  */
 298
 299 struct net_device *alloc_etherdev(int sizeof_priv)
 300 {
 301         return alloc_netdev(sizeof_priv, "eth%d", ether_setup);
 302 }
 303 EXPORT_SYMBOL(alloc_etherdev);