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, <bir7@leland.Stanford.Edu>
  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  *
  34  *              This program is free software; you can redistribute it and/or
  35  *              modify it under the terms of the GNU General Public License
  36  *              as published by the Free Software Foundation; either version
  37  *              2 of the License, or (at your option) any later version.
  38  */
  39 #include <linux/types.h>
  40 #include <linux/kernel.h>
  41 #include <linux/sched.h>
  42 #include <linux/string.h>
  43 #include <linux/mm.h>
  44 #include <linux/socket.h>
  45 #include <linux/in.h>
  46 #include <linux/inet.h>
  47 #include <linux/ip.h>
  48 #include <linux/netdevice.h>
  49 #include <linux/etherdevice.h>
  50 #include <linux/skbuff.h>
  51 #include <linux/errno.h>
  52 #include <linux/config.h>
  53 #include <linux/init.h>
  54 #include <net/dst.h>
  55 #include <net/arp.h>
  56 #include <net/sock.h>
  57 #include <net/ipv6.h>
  58 #include <net/ip.h>
  59 #include <asm/uaccess.h>
  60 #include <asm/system.h>
  61 #include <asm/checksum.h>
  62
  63
  64 __initfunc(void eth_setup(char *str, int *ints))
  65 {
  66         struct device *d;
  67
  68         if (!str || !*str)
  69                 return;
  70         read_lock_bh(&dev_base_lock);
  71         d = dev_base;
  72         while (d)
  73         {
  74                 if (!strcmp(str,d->name))
  75                 {
  76                         if (ints[0] > 0)
  77                                 d->irq=ints[1];
  78                         if (ints[0] > 1)
  79                                 d->base_addr=ints[2];
  80                         if (ints[0] > 2)
  81                                 d->mem_start=ints[3];
  82                         if (ints[0] > 3)
  83                                 d->mem_end=ints[4];
  84                         break;
  85                 }
  86                 d=d->next;
  87         }
  88         read_unlock_bh(&dev_base_lock);
  89 }
  90
  91
  92 /*
  93  *       Create the Ethernet MAC header for an arbitrary protocol layer
  94  *
  95  *      saddr=NULL      means use device source address
  96  *      daddr=NULL      means leave destination address (eg unresolved arp)
  97  */
  98
  99 int eth_header(struct sk_buff *skb, struct device *dev, unsigned short type,
 100            void *daddr, void *saddr, unsigned len)
 101 {
 102         struct ethhdr *eth = (struct ethhdr *)skb_push(skb,ETH_HLEN);
 103
 104         /*
 105          *      Set the protocol type. For a packet of type ETH_P_802_3 we put the length
 106          *      in here instead. It is up to the 802.2 layer to carry protocol information.
 107          */
 108
 109         if(type!=ETH_P_802_3)
 110                 eth->h_proto = htons(type);
 111         else
 112                 eth->h_proto = htons(len);
 113
 114         /*
 115          *      Set the source hardware address.
 116          */
 117
 118         if(saddr)
 119                 memcpy(eth->h_source,saddr,dev->addr_len);
 120         else
 121                 memcpy(eth->h_source,dev->dev_addr,dev->addr_len);
 122
 123         /*
 124          *      Anyway, the loopback-device should never use this function...
 125          */
 126
 127         if (dev->flags & (IFF_LOOPBACK|IFF_NOARP))
 128         {
 129                 memset(eth->h_dest, 0, dev->addr_len);
 130                 return(dev->hard_header_len);
 131         }
 132
 133         if(daddr)
 134         {
 135                 memcpy(eth->h_dest,daddr,dev->addr_len);
 136                 return dev->hard_header_len;
 137         }
 138
 139         return -dev->hard_header_len;
 140 }
 141
 142
 143 /*
 144  *      Rebuild the Ethernet MAC header. This is called after an ARP
 145  *      (or in future other address resolution) has completed on this
 146  *      sk_buff. We now let ARP fill in the other fields.
 147  *
 148  *      This routine CANNOT use cached dst->neigh!
 149  *      Really, it is used only when dst->neigh is wrong.
 150  */
 151
 152 int eth_rebuild_header(struct sk_buff *skb)
 153 {
 154         struct ethhdr *eth = (struct ethhdr *)skb->data;
 155         struct device *dev = skb->dev;
 156
 157         switch (eth->h_proto)
 158         {
 159 #ifdef CONFIG_INET
 160         case __constant_htons(ETH_P_IP):
 161                 return arp_find(eth->h_dest, skb);
 162 #endif
 163         default:
 164                 printk(KERN_DEBUG
 165                        "%s: unable to resolve type %X addresses.\n",
 166                        dev->name, (int)eth->h_proto);
 167
 168                 memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
 169                 break;
 170         }
 171
 172         return 0;
 173 }
 174
 175
 176 /*
 177  *      Determine the packet's protocol ID. The rule here is that we
 178  *      assume 802.3 if the type field is short enough to be a length.
 179  *      This is normal practice and works for any 'now in use' protocol.
 180  */
 181
 182 unsigned short eth_type_trans(struct sk_buff *skb, struct device *dev)
 183 {
 184         struct ethhdr *eth;
 185         unsigned char *rawp;
 186
 187         skb->mac.raw=skb->data;
 188         skb_pull(skb,dev->hard_header_len);
 189         eth= skb->mac.ethernet;
 190
 191         if(*eth->h_dest&1)
 192         {
 193                 if(memcmp(eth->h_dest,dev->broadcast, ETH_ALEN)==0)
 194                         skb->pkt_type=PACKET_BROADCAST;
 195                 else
 196                         skb->pkt_type=PACKET_MULTICAST;
 197         }
 198
 199         /*
 200          *      This ALLMULTI check should be redundant by 1.4
 201          *      so don't forget to remove it.
 202          *
 203          *      Seems, you forgot to remove it. All silly devices
 204          *      seems to set IFF_PROMISC.
 205          */
 206
 207         else if(dev->flags&(IFF_PROMISC/*|IFF_ALLMULTI*/))
 208         {
 209                 if(memcmp(eth->h_dest,dev->dev_addr, ETH_ALEN))
 210                         skb->pkt_type=PACKET_OTHERHOST;
 211         }
 212
 213         if (ntohs(eth->h_proto) >= 1536)
 214                 return eth->h_proto;
 215
 216         rawp = skb->data;
 217
 218         /*
 219          *      This is a magic hack to spot IPX packets. Older Novell breaks
 220          *      the protocol design and runs IPX over 802.3 without an 802.2 LLC
 221          *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
 222          *      won't work for fault tolerant netware but does for the rest.
 223          */
 224         if (*(unsigned short *)rawp == 0xFFFF)
 225                 return htons(ETH_P_802_3);
 226
 227         /*
 228          *      Real 802.2 LLC
 229          */
 230         return htons(ETH_P_802_2);
 231 }
 232
 233 int eth_header_parse(struct sk_buff *skb, unsigned char *haddr)
 234 {
 235         struct ethhdr *eth = skb->mac.ethernet;
 236         memcpy(haddr, eth->h_source, ETH_ALEN);
 237         return ETH_ALEN;
 238 }
 239
 240 int eth_header_cache(struct neighbour *neigh, struct hh_cache *hh)
 241 {
 242         unsigned short type = hh->hh_type;
 243         struct ethhdr *eth = (struct ethhdr*)(((u8*)hh->hh_data) + 2);
 244         struct device *dev = neigh->dev;
 245
 246         if (type == __constant_htons(ETH_P_802_3))
 247                 return -1;
 248
 249         eth->h_proto = type;
 250         memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
 251         memcpy(eth->h_dest, neigh->ha, dev->addr_len);
 252         return 0;
 253 }
 254
 255 /*
 256  * Called by Address Resolution module to notify changes in address.
 257  */
 258
 259 void eth_header_cache_update(struct hh_cache *hh, struct device *dev, unsigned char * haddr)
 260 {
 261         memcpy(((u8*)hh->hh_data) + 2, haddr, dev->addr_len);
 262 }
 263
 264 #ifndef CONFIG_IP_ROUTER
 265
 266 /*
 267  *      Copy from an ethernet device memory space to an sk_buff while checksumming if IP
 268  */
 269
 270 void eth_copy_and_sum(struct sk_buff *dest, unsigned char *src, int length, int base)
 271 {
 272         struct ethhdr *eth;
 273         struct iphdr *iph;
 274         int ip_length;
 275
 276         eth=(struct ethhdr *)src;
 277         if(eth->h_proto!=htons(ETH_P_IP))
 278         {
 279                 memcpy(dest->data,src,length);
 280                 return;
 281         }
 282         /*
 283          * We have to watch for padded packets. The csum doesn't include the
 284          * padding, and there is no point in copying the padding anyway.
 285          * We have to use the smaller of length and ip_length because it
 286          * can happen that ip_length > length.
 287          */
 288         memcpy(dest->data,src,sizeof(struct iphdr)+ETH_HLEN);   /* ethernet is always >= 34 */
 289         length -= sizeof(struct iphdr) + ETH_HLEN;
 290         iph=(struct iphdr*)(src+ETH_HLEN);
 291         ip_length = ntohs(iph->tot_len) - sizeof(struct iphdr);
 292
 293         /* Also watch out for bogons - min IP size is 8 (rfc-1042) */
 294         if ((ip_length <= length) && (ip_length > 7))
 295                 length=ip_length;
 296
 297         dest->csum=csum_partial_copy(src+sizeof(struct iphdr)+ETH_HLEN,dest->data+sizeof(struct iphdr)+ETH_HLEN,length,base);
 298         dest->ip_summed=1;
 299 }
 300
 301 #endif /* !(CONFIG_IP_ROUTER) */