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 static int __init eth_setup(char *str)
  64 {
  65         int ints[5];
  66         struct device *d;
  67
  68         str = get_options(str, ARRAY_SIZE(ints), ints);
  69
  70         if (!str || !*str)
  71                 return 0;
  72
  73         d = dev_base;
  74         while (d)
  75         {
  76                 if (!strcmp(str,d->name))
  77                 {
  78                         if (ints[0] > 0)
  79                                 d->irq=ints[1];
  80                         if (ints[0] > 1)
  81                                 d->base_addr=ints[2];
  82                         if (ints[0] > 2)
  83                                 d->mem_start=ints[3];
  84                         if (ints[0] > 3)
  85                                 d->mem_end=ints[4];
  86                         break;
  87                 }
  88                 d=d->next;
  89         }
  90         return 1;
  91 }
  92
  93 __setup("ether=", eth_setup);
  94
  95 /*
  96  *       Create the Ethernet MAC header for an arbitrary protocol layer
  97  *
  98  *      saddr=NULL      means use device source address
  99  *      daddr=NULL      means leave destination address (eg unresolved arp)
 100  */
 101
 102 int eth_header(struct sk_buff *skb, struct device *dev, unsigned short type,
 103            void *daddr, void *saddr, unsigned len)
 104 {
 105         struct ethhdr *eth = (struct ethhdr *)skb_push(skb,ETH_HLEN);
 106
 107         /*
 108          *      Set the protocol type. For a packet of type ETH_P_802_3 we put the length
 109          *      in here instead. It is up to the 802.2 layer to carry protocol information.
 110          */
 111
 112         if(type!=ETH_P_802_3)
 113                 eth->h_proto = htons(type);
 114         else
 115                 eth->h_proto = htons(len);
 116
 117         /*
 118          *      Set the source hardware address.
 119          */
 120
 121         if(saddr)
 122                 memcpy(eth->h_source,saddr,dev->addr_len);
 123         else
 124                 memcpy(eth->h_source,dev->dev_addr,dev->addr_len);
 125
 126         /*
 127          *      Anyway, the loopback-device should never use this function...
 128          */
 129
 130         if (dev->flags & (IFF_LOOPBACK|IFF_NOARP))
 131         {
 132                 memset(eth->h_dest, 0, dev->addr_len);
 133                 return(dev->hard_header_len);
 134         }
 135
 136         if(daddr)
 137         {
 138                 memcpy(eth->h_dest,daddr,dev->addr_len);
 139                 return dev->hard_header_len;
 140         }
 141
 142         return -dev->hard_header_len;
 143 }
 144
 145
 146 /*
 147  *      Rebuild the Ethernet MAC header. This is called after an ARP
 148  *      (or in future other address resolution) has completed on this
 149  *      sk_buff. We now let ARP fill in the other fields.
 150  *
 151  *      This routine CANNOT use cached dst->neigh!
 152  *      Really, it is used only when dst->neigh is wrong.
 153  */
 154
 155 int eth_rebuild_header(struct sk_buff *skb)
 156 {
 157         struct ethhdr *eth = (struct ethhdr *)skb->data;
 158         struct device *dev = skb->dev;
 159
 160         switch (eth->h_proto)
 161         {
 162 #ifdef CONFIG_INET
 163         case __constant_htons(ETH_P_IP):
 164                 return arp_find(eth->h_dest, skb);
 165 #endif
 166         default:
 167                 printk(KERN_DEBUG
 168                        "%s: unable to resolve type %X addresses.\n",
 169                        dev->name, (int)eth->h_proto);
 170
 171                 memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
 172                 break;
 173         }
 174
 175         return 0;
 176 }
 177
 178
 179 /*
 180  *      Determine the packet's protocol ID. The rule here is that we
 181  *      assume 802.3 if the type field is short enough to be a length.
 182  *      This is normal practice and works for any 'now in use' protocol.
 183  */
 184
 185 unsigned short eth_type_trans(struct sk_buff *skb, struct device *dev)
 186 {
 187         struct ethhdr *eth;
 188         unsigned char *rawp;
 189
 190         skb->mac.raw=skb->data;
 191         skb_pull(skb,dev->hard_header_len);
 192         eth= skb->mac.ethernet;
 193
 194         if(*eth->h_dest&1)
 195         {
 196                 if(memcmp(eth->h_dest,dev->broadcast, ETH_ALEN)==0)
 197                         skb->pkt_type=PACKET_BROADCAST;
 198                 else
 199                         skb->pkt_type=PACKET_MULTICAST;
 200         }
 201
 202         /*
 203          *      This ALLMULTI check should be redundant by 1.4
 204          *      so don't forget to remove it.
 205          *
 206          *      Seems, you forgot to remove it. All silly devices
 207          *      seems to set IFF_PROMISC.
 208          */
 209
 210         else if(dev->flags&(IFF_PROMISC/*|IFF_ALLMULTI*/))
 211         {
 212                 if(memcmp(eth->h_dest,dev->dev_addr, ETH_ALEN))
 213                         skb->pkt_type=PACKET_OTHERHOST;
 214         }
 215
 216         if (ntohs(eth->h_proto) >= 1536)
 217                 return eth->h_proto;
 218
 219         rawp = skb->data;
 220
 221         /*
 222          *      This is a magic hack to spot IPX packets. Older Novell breaks
 223          *      the protocol design and runs IPX over 802.3 without an 802.2 LLC
 224          *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
 225          *      won't work for fault tolerant netware but does for the rest.
 226          */
 227         if (*(unsigned short *)rawp == 0xFFFF)
 228                 return htons(ETH_P_802_3);
 229
 230         /*
 231          *      Real 802.2 LLC
 232          */
 233         return htons(ETH_P_802_2);
 234 }
 235
 236 int eth_header_parse(struct sk_buff *skb, unsigned char *haddr)
 237 {
 238         struct ethhdr *eth = skb->mac.ethernet;
 239         memcpy(haddr, eth->h_source, ETH_ALEN);
 240         return ETH_ALEN;
 241 }
 242
 243 int eth_header_cache(struct neighbour *neigh, struct hh_cache *hh)
 244 {
 245         unsigned short type = hh->hh_type;
 246         struct ethhdr *eth = (struct ethhdr*)(((u8*)hh->hh_data) + 2);
 247         struct device *dev = neigh->dev;
 248
 249         if (type == __constant_htons(ETH_P_802_3))
 250                 return -1;
 251
 252         eth->h_proto = type;
 253         memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
 254         memcpy(eth->h_dest, neigh->ha, dev->addr_len);
 255         hh->hh_len = ETH_HLEN;
 256         return 0;
 257 }
 258
 259 /*
 260  * Called by Address Resolution module to notify changes in address.
 261  */
 262
 263 void eth_header_cache_update(struct hh_cache *hh, struct device *dev, unsigned char * haddr)
 264 {
 265         memcpy(((u8*)hh->hh_data) + 2, haddr, dev->addr_len);
 266 }
 267
 268 #ifndef CONFIG_IP_ROUTER
 269
 270 /*
 271  *      Copy from an ethernet device memory space to an sk_buff while checksumming if IP
 272  */
 273
 274 void eth_copy_and_sum(struct sk_buff *dest, unsigned char *src, int length, int base)
 275 {
 276         struct ethhdr *eth;
 277         struct iphdr *iph;
 278         int ip_length;
 279
 280         eth=(struct ethhdr *)src;
 281         if(eth->h_proto!=htons(ETH_P_IP))
 282         {
 283                 memcpy(dest->data,src,length);
 284                 return;
 285         }
 286         /*
 287          * We have to watch for padded packets. The csum doesn't include the
 288          * padding, and there is no point in copying the padding anyway.
 289          * We have to use the smaller of length and ip_length because it
 290          * can happen that ip_length > length.
 291          */
 292         memcpy(dest->data,src,sizeof(struct iphdr)+ETH_HLEN);   /* ethernet is always >= 34 */
 293         length -= sizeof(struct iphdr) + ETH_HLEN;
 294         iph=(struct iphdr*)(src+ETH_HLEN);
 295         ip_length = ntohs(iph->tot_len) - sizeof(struct iphdr);
 296
 297         /* Also watch out for bogons - min IP size is 8 (rfc-1042) */
 298         if ((ip_length <= length) && (ip_length > 7))
 299                 length=ip_length;
 300
 301         dest->csum=csum_partial_copy(src+sizeof(struct iphdr)+ETH_HLEN,dest->data+sizeof(struct iphdr)+ETH_HLEN,length,base);
 302         dest->ip_summed=1;
 303 }
 304
 305 #endif /* !(CONFIG_IP_ROUTER) */