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/string.h>
  44 #include <linux/mm.h>
  45 #include <linux/socket.h>
  46 #include <linux/in.h>
  47 #include <linux/inet.h>
  48 #include <linux/ip.h>
  49 #include <linux/netdevice.h>
  50 #include <linux/etherdevice.h>
  51 #include <linux/skbuff.h>
  52 #include <linux/errno.h>
  53 #include <linux/init.h>
  54 #include <linux/if_ether.h>
  55 #include <net/dst.h>
  56 #include <net/arp.h>
  57 #include <net/sock.h>
  58 #include <net/ipv6.h>
  59 #include <net/ip.h>
  60 #include <net/dsa.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_3/2 we put the length
  77  * in here instead.
  78  */
  79 int eth_header(struct sk_buff *skb, struct net_device *dev,
  80                unsigned short type,
  81                const void *daddr, const void *saddr, unsigned len)
  82 {
  83         struct ethhdr *eth = (struct ethhdr *)skb_push(skb, ETH_HLEN);
  84
  85         if (type != ETH_P_802_3 && type != ETH_P_802_2)
  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, ETH_ALEN);
  97
  98         if (daddr) {
  99                 memcpy(eth->h_dest, daddr, ETH_ALEN);
 100                 return ETH_HLEN;
 101         }
 102
 103         /*
 104          *      Anyway, the loopback-device should never use this function...
 105          */
 106
 107         if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
 108                 memset(eth->h_dest, 0, ETH_ALEN);
 109                 return ETH_HLEN;
 110         }
 111
 112         return -ETH_HLEN;
 113 }
 114 EXPORT_SYMBOL(eth_header);
 115
 116 /**
 117  * eth_rebuild_header- rebuild the Ethernet MAC header.
 118  * @skb: socket buffer to update
 119  *
 120  * This is called after an ARP or IPV6 ndisc it's resolution on this
 121  * sk_buff. We now let protocol (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 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 #ifdef CONFIG_INET
 133         case htons(ETH_P_IP):
 134                 return arp_find(eth->h_dest, skb);
 135 #endif
 136         default:
 137                 printk(KERN_DEBUG
 138                        "%s: unable to resolve type %X addresses.\n",
 139                        dev->name, ntohs(eth->h_proto));
 140
 141                 memcpy(eth->h_source, dev->dev_addr, ETH_ALEN);
 142                 break;
 143         }
 144
 145         return 0;
 146 }
 147 EXPORT_SYMBOL(eth_rebuild_header);
 148
 149 /**
 150  * eth_type_trans - determine the packet's protocol ID.
 151  * @skb: received socket data
 152  * @dev: receiving network device
 153  *
 154  * The rule here is that we
 155  * assume 802.3 if the type field is short enough to be a length.
 156  * This is normal practice and works for any 'now in use' protocol.
 157  */
 158 __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
 159 {
 160         struct ethhdr *eth;
 161
 162         skb->dev = dev;
 163         skb_reset_mac_header(skb);
 164         skb_pull_inline(skb, ETH_HLEN);
 165         eth = eth_hdr(skb);
 166
 167         if (unlikely(is_multicast_ether_addr(eth->h_dest))) {
 168                 if (!compare_ether_addr_64bits(eth->h_dest, dev->broadcast))
 169                         skb->pkt_type = PACKET_BROADCAST;
 170                 else
 171                         skb->pkt_type = PACKET_MULTICAST;
 172         }
 173
 174         /*
 175          *      This ALLMULTI check should be redundant by 1.4
 176          *      so don't forget to remove it.
 177          *
 178          *      Seems, you forgot to remove it. All silly devices
 179          *      seems to set IFF_PROMISC.
 180          */
 181
 182         else if (1 /*dev->flags&IFF_PROMISC */ ) {
 183                 if (unlikely(compare_ether_addr_64bits(eth->h_dest, dev->dev_addr)))
 184                         skb->pkt_type = PACKET_OTHERHOST;
 185         }
 186
 187         /*
 188          * Some variants of DSA tagging don't have an ethertype field
 189          * at all, so we check here whether one of those tagging
 190          * variants has been configured on the receiving interface,
 191          * and if so, set skb->protocol without looking at the packet.
 192          */
 193         if (netdev_uses_dsa_tags(dev))
 194                 return htons(ETH_P_DSA);
 195         if (netdev_uses_trailer_tags(dev))
 196                 return htons(ETH_P_TRAILER);
 197
 198         if (ntohs(eth->h_proto) >= 1536)
 199                 return eth->h_proto;
 200
 201         /*
 202          *      This is a magic hack to spot IPX packets. Older Novell breaks
 203          *      the protocol design and runs IPX over 802.3 without an 802.2 LLC
 204          *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
 205          *      won't work for fault tolerant netware but does for the rest.
 206          */
 207         if (skb->len >= 2 && *(unsigned short *)(skb->data) == 0xFFFF)
 208                 return htons(ETH_P_802_3);
 209
 210         /*
 211          *      Real 802.2 LLC
 212          */
 213         return htons(ETH_P_802_2);
 214 }
 215 EXPORT_SYMBOL(eth_type_trans);
 216
 217 /**
 218  * eth_header_parse - extract hardware address from packet
 219  * @skb: packet to extract header from
 220  * @haddr: destination buffer
 221  */
 222 int eth_header_parse(const struct sk_buff *skb, unsigned char *haddr)
 223 {
 224         const struct ethhdr *eth = eth_hdr(skb);
 225         memcpy(haddr, eth->h_source, ETH_ALEN);
 226         return ETH_ALEN;
 227 }
 228 EXPORT_SYMBOL(eth_header_parse);
 229
 230 /**
 231  * eth_header_cache - fill cache entry from neighbour
 232  * @neigh: source neighbour
 233  * @hh: destination cache entry
 234  * Create an Ethernet header template from the neighbour.
 235  */
 236 int eth_header_cache(const struct neighbour *neigh, struct hh_cache *hh)
 237 {
 238         __be16 type = hh->hh_type;
 239         struct ethhdr *eth;
 240         const struct net_device *dev = neigh->dev;
 241
 242         eth = (struct ethhdr *)
 243             (((u8 *) hh->hh_data) + (HH_DATA_OFF(sizeof(*eth))));
 244
 245         if (type == htons(ETH_P_802_3))
 246                 return -1;
 247
 248         eth->h_proto = type;
 249         memcpy(eth->h_source, dev->dev_addr, ETH_ALEN);
 250         memcpy(eth->h_dest, neigh->ha, ETH_ALEN);
 251         hh->hh_len = ETH_HLEN;
 252         return 0;
 253 }
 254 EXPORT_SYMBOL(eth_header_cache);
 255
 256 /**
 257  * eth_header_cache_update - update cache entry
 258  * @hh: destination cache entry
 259  * @dev: network device
 260  * @haddr: new hardware address
 261  *
 262  * Called by Address Resolution module to notify changes in address.
 263  */
 264 void eth_header_cache_update(struct hh_cache *hh,
 265                              const struct net_device *dev,
 266                              const unsigned char *haddr)
 267 {
 268         memcpy(((u8 *) hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)),
 269                haddr, ETH_ALEN);
 270 }
 271 EXPORT_SYMBOL(eth_header_cache_update);
 272
 273 /**
 274  * eth_mac_addr - set new Ethernet hardware address
 275  * @dev: network device
 276  * @p: socket address
 277  * Change hardware address of device.
 278  *
 279  * This doesn't change hardware matching, so needs to be overridden
 280  * for most real devices.
 281  */
 282 int eth_mac_addr(struct net_device *dev, void *p)
 283 {
 284         struct sockaddr *addr = p;
 285
 286         if (netif_running(dev))
 287                 return -EBUSY;
 288         if (!is_valid_ether_addr(addr->sa_data))
 289                 return -EADDRNOTAVAIL;
 290         memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
 291         return 0;
 292 }
 293 EXPORT_SYMBOL(eth_mac_addr);
 294
 295 /**
 296  * eth_change_mtu - set new MTU size
 297  * @dev: network device
 298  * @new_mtu: new Maximum Transfer Unit
 299  *
 300  * Allow changing MTU size. Needs to be overridden for devices
 301  * supporting jumbo frames.
 302  */
 303 int eth_change_mtu(struct net_device *dev, int new_mtu)
 304 {
 305         if (new_mtu < 68 || new_mtu > ETH_DATA_LEN)
 306                 return -EINVAL;
 307         dev->mtu = new_mtu;
 308         return 0;
 309 }
 310 EXPORT_SYMBOL(eth_change_mtu);
 311
 312 int eth_validate_addr(struct net_device *dev)
 313 {
 314         if (!is_valid_ether_addr(dev->dev_addr))
 315                 return -EADDRNOTAVAIL;
 316
 317         return 0;
 318 }
 319 EXPORT_SYMBOL(eth_validate_addr);
 320
 321 const struct header_ops eth_header_ops ____cacheline_aligned = {
 322         .create         = eth_header,
 323         .parse          = eth_header_parse,
 324         .rebuild        = eth_rebuild_header,
 325         .cache          = eth_header_cache,
 326         .cache_update   = eth_header_cache_update,
 327 };
 328
 329 /**
 330  * ether_setup - setup Ethernet network device
 331  * @dev: network device
 332  * Fill in the fields of the device structure with Ethernet-generic values.
 333  */
 334 void ether_setup(struct net_device *dev)
 335 {
 336         dev->header_ops         = &eth_header_ops;
 337         dev->type               = ARPHRD_ETHER;
 338         dev->hard_header_len    = ETH_HLEN;
 339         dev->mtu                = ETH_DATA_LEN;
 340         dev->addr_len           = ETH_ALEN;
 341         dev->tx_queue_len       = 1000; /* Ethernet wants good queues */
 342         dev->flags              = IFF_BROADCAST|IFF_MULTICAST;
 343
 344         memset(dev->broadcast, 0xFF, ETH_ALEN);
 345
 346 }
 347 EXPORT_SYMBOL(ether_setup);
 348
 349 /**
 350  * alloc_etherdev_mq - Allocates and sets up an Ethernet device
 351  * @sizeof_priv: Size of additional driver-private structure to be allocated
 352  *      for this Ethernet device
 353  * @queue_count: The number of queues this device has.
 354  *
 355  * Fill in the fields of the device structure with Ethernet-generic
 356  * values. Basically does everything except registering the device.
 357  *
 358  * Constructs a new net device, complete with a private data area of
 359  * size (sizeof_priv).  A 32-byte (not bit) alignment is enforced for
 360  * this private data area.
 361  */
 362
 363 struct net_device *alloc_etherdev_mq(int sizeof_priv, unsigned int queue_count)
 364 {
 365         return alloc_netdev_mq(sizeof_priv, "eth%d", ether_setup, queue_count);
 366 }
 367 EXPORT_SYMBOL(alloc_etherdev_mq);
 368
 369 static size_t _format_mac_addr(char *buf, int buflen,
 370                                const unsigned char *addr, int len)
 371 {
 372         int i;
 373         char *cp = buf;
 374
 375         for (i = 0; i < len; i++) {
 376                 cp += scnprintf(cp, buflen - (cp - buf), "%02x", addr[i]);
 377                 if (i == len - 1)
 378                         break;
 379                 cp += scnprintf(cp, buflen - (cp - buf), ":");
 380         }
 381         return cp - buf;
 382 }
 383
 384 ssize_t sysfs_format_mac(char *buf, const unsigned char *addr, int len)
 385 {
 386         size_t l;
 387
 388         l = _format_mac_addr(buf, PAGE_SIZE, addr, len);
 389         l += scnprintf(buf + l, PAGE_SIZE - l, "\n");
 390         return (ssize_t)l;
 391 }
 392 EXPORT_SYMBOL(sysfs_format_mac);