linux/net/ethernet/eth.c
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   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 */
  79int 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}
 114EXPORT_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 */
 126int 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}
 147EXPORT_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        unsigned char *rawp;
 162
 163        skb->dev = dev;
 164        skb_reset_mac_header(skb);
 165        skb_pull_inline(skb, ETH_HLEN);
 166        eth = eth_hdr(skb);
 167
 168        if (unlikely(is_multicast_ether_addr(eth->h_dest))) {
 169                if (!compare_ether_addr_64bits(eth->h_dest, dev->broadcast))
 170                        skb->pkt_type = PACKET_BROADCAST;
 171                else
 172                        skb->pkt_type = PACKET_MULTICAST;
 173        }
 174
 175        /*
 176         *      This ALLMULTI check should be redundant by 1.4
 177         *      so don't forget to remove it.
 178         *
 179         *      Seems, you forgot to remove it. All silly devices
 180         *      seems to set IFF_PROMISC.
 181         */
 182
 183        else if (1 /*dev->flags&IFF_PROMISC */ ) {
 184                if (unlikely(compare_ether_addr_64bits(eth->h_dest, dev->dev_addr)))
 185                        skb->pkt_type = PACKET_OTHERHOST;
 186        }
 187
 188        /*
 189         * Some variants of DSA tagging don't have an ethertype field
 190         * at all, so we check here whether one of those tagging
 191         * variants has been configured on the receiving interface,
 192         * and if so, set skb->protocol without looking at the packet.
 193         */
 194        if (netdev_uses_dsa_tags(dev))
 195                return htons(ETH_P_DSA);
 196        if (netdev_uses_trailer_tags(dev))
 197                return htons(ETH_P_TRAILER);
 198
 199        if (ntohs(eth->h_proto) >= 1536)
 200                return eth->h_proto;
 201
 202        rawp = skb->data;
 203
 204        /*
 205         *      This is a magic hack to spot IPX packets. Older Novell breaks
 206         *      the protocol design and runs IPX over 802.3 without an 802.2 LLC
 207         *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
 208         *      won't work for fault tolerant netware but does for the rest.
 209         */
 210        if (*(unsigned short *)rawp == 0xFFFF)
 211                return htons(ETH_P_802_3);
 212
 213        /*
 214         *      Real 802.2 LLC
 215         */
 216        return htons(ETH_P_802_2);
 217}
 218EXPORT_SYMBOL(eth_type_trans);
 219
 220/**
 221 * eth_header_parse - extract hardware address from packet
 222 * @skb: packet to extract header from
 223 * @haddr: destination buffer
 224 */
 225int eth_header_parse(const struct sk_buff *skb, unsigned char *haddr)
 226{
 227        const struct ethhdr *eth = eth_hdr(skb);
 228        memcpy(haddr, eth->h_source, ETH_ALEN);
 229        return ETH_ALEN;
 230}
 231EXPORT_SYMBOL(eth_header_parse);
 232
 233/**
 234 * eth_header_cache - fill cache entry from neighbour
 235 * @neigh: source neighbour
 236 * @hh: destination cache entry
 237 * Create an Ethernet header template from the neighbour.
 238 */
 239int eth_header_cache(const struct neighbour *neigh, struct hh_cache *hh)
 240{
 241        __be16 type = hh->hh_type;
 242        struct ethhdr *eth;
 243        const struct net_device *dev = neigh->dev;
 244
 245        eth = (struct ethhdr *)
 246            (((u8 *) hh->hh_data) + (HH_DATA_OFF(sizeof(*eth))));
 247
 248        if (type == htons(ETH_P_802_3))
 249                return -1;
 250
 251        eth->h_proto = type;
 252        memcpy(eth->h_source, dev->dev_addr, ETH_ALEN);
 253        memcpy(eth->h_dest, neigh->ha, ETH_ALEN);
 254        hh->hh_len = ETH_HLEN;
 255        return 0;
 256}
 257EXPORT_SYMBOL(eth_header_cache);
 258
 259/**
 260 * eth_header_cache_update - update cache entry
 261 * @hh: destination cache entry
 262 * @dev: network device
 263 * @haddr: new hardware address
 264 *
 265 * Called by Address Resolution module to notify changes in address.
 266 */
 267void eth_header_cache_update(struct hh_cache *hh,
 268                             const struct net_device *dev,
 269                             const unsigned char *haddr)
 270{
 271        memcpy(((u8 *) hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)),
 272               haddr, ETH_ALEN);
 273}
 274EXPORT_SYMBOL(eth_header_cache_update);
 275
 276/**
 277 * eth_mac_addr - set new Ethernet hardware address
 278 * @dev: network device
 279 * @p: socket address
 280 * Change hardware address of device.
 281 *
 282 * This doesn't change hardware matching, so needs to be overridden
 283 * for most real devices.
 284 */
 285int eth_mac_addr(struct net_device *dev, void *p)
 286{
 287        struct sockaddr *addr = p;
 288
 289        if (netif_running(dev))
 290                return -EBUSY;
 291        if (!is_valid_ether_addr(addr->sa_data))
 292                return -EADDRNOTAVAIL;
 293        memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
 294        return 0;
 295}
 296EXPORT_SYMBOL(eth_mac_addr);
 297
 298/**
 299 * eth_change_mtu - set new MTU size
 300 * @dev: network device
 301 * @new_mtu: new Maximum Transfer Unit
 302 *
 303 * Allow changing MTU size. Needs to be overridden for devices
 304 * supporting jumbo frames.
 305 */
 306int eth_change_mtu(struct net_device *dev, int new_mtu)
 307{
 308        if (new_mtu < 68 || new_mtu > ETH_DATA_LEN)
 309                return -EINVAL;
 310        dev->mtu = new_mtu;
 311        return 0;
 312}
 313EXPORT_SYMBOL(eth_change_mtu);
 314
 315int eth_validate_addr(struct net_device *dev)
 316{
 317        if (!is_valid_ether_addr(dev->dev_addr))
 318                return -EADDRNOTAVAIL;
 319
 320        return 0;
 321}
 322EXPORT_SYMBOL(eth_validate_addr);
 323
 324const struct header_ops eth_header_ops ____cacheline_aligned = {
 325        .create         = eth_header,
 326        .parse          = eth_header_parse,
 327        .rebuild        = eth_rebuild_header,
 328        .cache          = eth_header_cache,
 329        .cache_update   = eth_header_cache_update,
 330};
 331
 332/**
 333 * ether_setup - setup Ethernet network device
 334 * @dev: network device
 335 * Fill in the fields of the device structure with Ethernet-generic values.
 336 */
 337void ether_setup(struct net_device *dev)
 338{
 339        dev->header_ops         = &eth_header_ops;
 340        dev->type               = ARPHRD_ETHER;
 341        dev->hard_header_len    = ETH_HLEN;
 342        dev->mtu                = ETH_DATA_LEN;
 343        dev->addr_len           = ETH_ALEN;
 344        dev->tx_queue_len       = 1000; /* Ethernet wants good queues */
 345        dev->flags              = IFF_BROADCAST|IFF_MULTICAST;
 346
 347        memset(dev->broadcast, 0xFF, ETH_ALEN);
 348
 349}
 350EXPORT_SYMBOL(ether_setup);
 351
 352/**
 353 * alloc_etherdev_mq - Allocates and sets up an Ethernet device
 354 * @sizeof_priv: Size of additional driver-private structure to be allocated
 355 *      for this Ethernet device
 356 * @queue_count: The number of queues this device has.
 357 *
 358 * Fill in the fields of the device structure with Ethernet-generic
 359 * values. Basically does everything except registering the device.
 360 *
 361 * Constructs a new net device, complete with a private data area of
 362 * size (sizeof_priv).  A 32-byte (not bit) alignment is enforced for
 363 * this private data area.
 364 */
 365
 366struct net_device *alloc_etherdev_mq(int sizeof_priv, unsigned int queue_count)
 367{
 368        return alloc_netdev_mq(sizeof_priv, "eth%d", ether_setup, queue_count);
 369}
 370EXPORT_SYMBOL(alloc_etherdev_mq);
 371
 372static size_t _format_mac_addr(char *buf, int buflen,
 373                                const unsigned char *addr, int len)
 374{
 375        int i;
 376        char *cp = buf;
 377
 378        for (i = 0; i < len; i++) {
 379                cp += scnprintf(cp, buflen - (cp - buf), "%02x", addr[i]);
 380                if (i == len - 1)
 381                        break;
 382                cp += strlcpy(cp, ":", buflen - (cp - buf));
 383        }
 384        return cp - buf;
 385}
 386
 387ssize_t sysfs_format_mac(char *buf, const unsigned char *addr, int len)
 388{
 389        size_t l;
 390
 391        l = _format_mac_addr(buf, PAGE_SIZE, addr, len);
 392        l += strlcpy(buf + l, "\n", PAGE_SIZE - l);
 393        return ((ssize_t) l);
 394}
 395EXPORT_SYMBOL(sysfs_format_mac);
 396
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