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/init.h>
  55 #include <linux/if_ether.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
  64 __setup("ether=", netdev_boot_setup);
  65
  66 /**
  67  * eth_header - create the Ethernet header
  68  * @skb:        buffer to alter
  69  * @dev:        source device
  70  * @type:       Ethernet type field
  71  * @daddr: destination address (NULL leave destination address)
  72  * @saddr: source address (NULL use device source address)
  73  * @len:   packet length (<= skb->len)
  74  *
  75  *
  76  * Set the protocol type. For a packet of type ETH_P_802_3 we put the length
  77  * in here instead. It is up to the 802.2 layer to carry protocol information.
  78  */
  79 int eth_header(struct sk_buff *skb, struct net_device *dev, unsigned short type,
  80                void *daddr, void *saddr, unsigned len)
  81 {
  82         struct ethhdr *eth = (struct ethhdr *)skb_push(skb, ETH_HLEN);
  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         if (daddr) {
  98                 memcpy(eth->h_dest, daddr, dev->addr_len);
  99                 return ETH_HLEN;
 100         }
 101
 102         /*
 103          *      Anyway, the loopback-device should never use this function...
 104          */
 105
 106         if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
 107                 memset(eth->h_dest, 0, dev->addr_len);
 108                 return ETH_HLEN;
 109         }
 110
 111         return -ETH_HLEN;
 112 }
 113
 114 /**
 115  * eth_rebuild_header- rebuild the Ethernet MAC header.
 116  * @skb: socket buffer to update
 117  *
 118  * This is called after an ARP or IPV6 ndisc it's resolution on this
 119  * sk_buff. We now let protocol (ARP) fill in the other fields.
 120  *
 121  * This routine CANNOT use cached dst->neigh!
 122  * Really, it is used only when dst->neigh is wrong.
 123  */
 124 int eth_rebuild_header(struct sk_buff *skb)
 125 {
 126         struct ethhdr *eth = (struct ethhdr *)skb->data;
 127         struct net_device *dev = skb->dev;
 128
 129         switch (eth->h_proto) {
 130 #ifdef CONFIG_INET
 131         case __constant_htons(ETH_P_IP):
 132                 return arp_find(eth->h_dest, skb);
 133 #endif
 134         default:
 135                 printk(KERN_DEBUG
 136                        "%s: unable to resolve type %X addresses.\n",
 137                        dev->name, (int)eth->h_proto);
 138
 139                 memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
 140                 break;
 141         }
 142
 143         return 0;
 144 }
 145
 146 /**
 147  * eth_type_trans - determine the packet's protocol ID.
 148  * @skb: received socket data
 149  * @dev: receiving network device
 150  *
 151  * The rule here is that we
 152  * assume 802.3 if the type field is short enough to be a length.
 153  * This is normal practice and works for any 'now in use' protocol.
 154  */
 155 __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
 156 {
 157         struct ethhdr *eth;
 158         unsigned char *rawp;
 159
 160         skb->mac.raw = skb->data;
 161         skb_pull(skb, ETH_HLEN);
 162         eth = eth_hdr(skb);
 163
 164         if (is_multicast_ether_addr(eth->h_dest)) {
 165                 if (!compare_ether_addr(eth->h_dest, dev->broadcast))
 166                         skb->pkt_type = PACKET_BROADCAST;
 167                 else
 168                         skb->pkt_type = PACKET_MULTICAST;
 169         }
 170
 171         /*
 172          *      This ALLMULTI check should be redundant by 1.4
 173          *      so don't forget to remove it.
 174          *
 175          *      Seems, you forgot to remove it. All silly devices
 176          *      seems to set IFF_PROMISC.
 177          */
 178
 179         else if (1 /*dev->flags&IFF_PROMISC */ ) {
 180                 if (unlikely(compare_ether_addr(eth->h_dest, dev->dev_addr)))
 181                         skb->pkt_type = PACKET_OTHERHOST;
 182         }
 183
 184         if (ntohs(eth->h_proto) >= 1536)
 185                 return eth->h_proto;
 186
 187         rawp = skb->data;
 188
 189         /*
 190          *      This is a magic hack to spot IPX packets. Older Novell breaks
 191          *      the protocol design and runs IPX over 802.3 without an 802.2 LLC
 192          *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
 193          *      won't work for fault tolerant netware but does for the rest.
 194          */
 195         if (*(unsigned short *)rawp == 0xFFFF)
 196                 return htons(ETH_P_802_3);
 197
 198         /*
 199          *      Real 802.2 LLC
 200          */
 201         return htons(ETH_P_802_2);
 202 }
 203 EXPORT_SYMBOL(eth_type_trans);
 204
 205 /**
 206  * eth_header_parse - extract hardware address from packet
 207  * @skb: packet to extract header from
 208  * @haddr: destination buffer
 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 /**
 218  * eth_header_cache - fill cache entry from neighbour
 219  * @neigh: source neighbour
 220  * @hh: destination cache entry
 221  * Create an Ethernet header template from the neighbour.
 222  */
 223 int eth_header_cache(struct neighbour *neigh, struct hh_cache *hh)
 224 {
 225         __be16 type = hh->hh_type;
 226         struct ethhdr *eth;
 227         struct net_device *dev = neigh->dev;
 228
 229         eth = (struct ethhdr *)
 230             (((u8 *) hh->hh_data) + (HH_DATA_OFF(sizeof(*eth))));
 231
 232         if (type == __constant_htons(ETH_P_802_3))
 233                 return -1;
 234
 235         eth->h_proto = type;
 236         memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
 237         memcpy(eth->h_dest, neigh->ha, dev->addr_len);
 238         hh->hh_len = ETH_HLEN;
 239         return 0;
 240 }
 241
 242 /**
 243  * eth_header_cache_update - update cache entry
 244  * @hh: destination cache entry
 245  * @dev: network device
 246  * @haddr: new hardware address
 247  *
 248  * Called by Address Resolution module to notify changes in address.
 249  */
 250 void eth_header_cache_update(struct hh_cache *hh, struct net_device *dev,
 251                              unsigned char *haddr)
 252 {
 253         memcpy(((u8 *) hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)),
 254                haddr, dev->addr_len);
 255 }
 256
 257 /**
 258  * eth_mac_addr - set new Ethernet hardware address
 259  * @dev: network device
 260  * @p: socket address
 261  * Change hardware address of device.
 262  *
 263  * This doesn't change hardware matching, so needs to be overridden
 264  * for most real devices.
 265  */
 266 static int eth_mac_addr(struct net_device *dev, void *p)
 267 {
 268         struct sockaddr *addr = p;
 269         if (netif_running(dev))
 270                 return -EBUSY;
 271         memcpy(dev->dev_addr, addr->sa_data, dev->addr_len);
 272         return 0;
 273 }
 274
 275 /**
 276  * eth_change_mtu - set new MTU size
 277  * @dev: network device
 278  * @new_mtu: new Maximum Transfer Unit
 279  *
 280  * Allow changing MTU size. Needs to be overridden for devices
 281  * supporting jumbo frames.
 282  */
 283 static int eth_change_mtu(struct net_device *dev, int new_mtu)
 284 {
 285         if (new_mtu < 68 || new_mtu > ETH_DATA_LEN)
 286                 return -EINVAL;
 287         dev->mtu = new_mtu;
 288         return 0;
 289 }
 290
 291 /**
 292  * ether_setup - setup Ethernet network device
 293  * @dev: network device
 294  * Fill in the fields of the device structure with Ethernet-generic values.
 295  */
 296 void ether_setup(struct net_device *dev)
 297 {
 298         dev->change_mtu         = eth_change_mtu;
 299         dev->hard_header        = eth_header;
 300         dev->rebuild_header     = eth_rebuild_header;
 301         dev->set_mac_address    = eth_mac_addr;
 302         dev->hard_header_cache  = eth_header_cache;
 303         dev->header_cache_update= eth_header_cache_update;
 304         dev->hard_header_parse  = eth_header_parse;
 305
 306         dev->type               = ARPHRD_ETHER;
 307         dev->hard_header_len    = ETH_HLEN;
 308         dev->mtu                = ETH_DATA_LEN;
 309         dev->addr_len           = ETH_ALEN;
 310         dev->tx_queue_len       = 1000; /* Ethernet wants good queues */
 311         dev->flags              = IFF_BROADCAST|IFF_MULTICAST;
 312
 313         memset(dev->broadcast, 0xFF, ETH_ALEN);
 314
 315 }
 316 EXPORT_SYMBOL(ether_setup);
 317
 318 /**
 319  * alloc_etherdev - Allocates and sets up an Ethernet device
 320  * @sizeof_priv: Size of additional driver-private structure to be allocated
 321  *      for this Ethernet device
 322  *
 323  * Fill in the fields of the device structure with Ethernet-generic
 324  * values. Basically does everything except registering the device.
 325  *
 326  * Constructs a new net device, complete with a private data area of
 327  * size (sizeof_priv).  A 32-byte (not bit) alignment is enforced for
 328  * this private data area.
 329  */
 330
 331 struct net_device *alloc_etherdev(int sizeof_priv)
 332 {
 333         return alloc_netdev(sizeof_priv, "eth%d", ether_setup);
 334 }
 335 EXPORT_SYMBOL(alloc_etherdev);