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
  63__setup("ether=", netdev_boot_setup);
  64
  65/**
  66 * eth_header - create the Ethernet header
  67 * @skb:        buffer to alter
  68 * @dev:        source device
  69 * @type:       Ethernet type field
  70 * @daddr: destination address (NULL leave destination address)
  71 * @saddr: source address (NULL use device source address)
  72 * @len:   packet length (<= skb->len)
  73 *
  74 *
  75 * Set the protocol type. For a packet of type ETH_P_802_3/2 we put the length
  76 * in here instead.
  77 */
  78int eth_header(struct sk_buff *skb, struct net_device *dev,
  79               unsigned short type,
  80               const void *daddr, const void *saddr, unsigned int len)
  81{
  82        struct ethhdr *eth = (struct ethhdr *)skb_push(skb, ETH_HLEN);
  83
  84        if (type != ETH_P_802_3 && type != ETH_P_802_2)
  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, ETH_ALEN);
  96
  97        if (daddr) {
  98                memcpy(eth->h_dest, daddr, ETH_ALEN);
  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, ETH_ALEN);
 108                return ETH_HLEN;
 109        }
 110
 111        return -ETH_HLEN;
 112}
 113EXPORT_SYMBOL(eth_header);
 114
 115/**
 116 * eth_rebuild_header- rebuild the Ethernet MAC header.
 117 * @skb: socket buffer to update
 118 *
 119 * This is called after an ARP or IPV6 ndisc it's resolution on this
 120 * sk_buff. We now let protocol (ARP) fill in the other fields.
 121 *
 122 * This routine CANNOT use cached dst->neigh!
 123 * Really, it is used only when dst->neigh is wrong.
 124 */
 125int eth_rebuild_header(struct sk_buff *skb)
 126{
 127        struct ethhdr *eth = (struct ethhdr *)skb->data;
 128        struct net_device *dev = skb->dev;
 129
 130        switch (eth->h_proto) {
 131#ifdef CONFIG_INET
 132        case htons(ETH_P_IP):
 133                return arp_find(eth->h_dest, skb);
 134#endif
 135        default:
 136                printk(KERN_DEBUG
 137                       "%s: unable to resolve type %X addresses.\n",
 138                       dev->name, ntohs(eth->h_proto));
 139
 140                memcpy(eth->h_source, dev->dev_addr, ETH_ALEN);
 141                break;
 142        }
 143
 144        return 0;
 145}
 146EXPORT_SYMBOL(eth_rebuild_header);
 147
 148/**
 149 * eth_type_trans - determine the packet's protocol ID.
 150 * @skb: received socket data
 151 * @dev: receiving network device
 152 *
 153 * The rule here is that we
 154 * assume 802.3 if the type field is short enough to be a length.
 155 * This is normal practice and works for any 'now in use' protocol.
 156 */
 157__be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
 158{
 159        struct ethhdr *eth;
 160
 161        skb->dev = dev;
 162        skb_reset_mac_header(skb);
 163        skb_pull_inline(skb, ETH_HLEN);
 164        eth = eth_hdr(skb);
 165
 166        if (unlikely(is_multicast_ether_addr(eth->h_dest))) {
 167                if (ether_addr_equal_64bits(eth->h_dest, dev->broadcast))
 168                        skb->pkt_type = PACKET_BROADCAST;
 169                else
 170                        skb->pkt_type = PACKET_MULTICAST;
 171        }
 172
 173        /*
 174         *      This ALLMULTI check should be redundant by 1.4
 175         *      so don't forget to remove it.
 176         *
 177         *      Seems, you forgot to remove it. All silly devices
 178         *      seems to set IFF_PROMISC.
 179         */
 180
 181        else if (1 /*dev->flags&IFF_PROMISC */ ) {
 182                if (unlikely(!ether_addr_equal_64bits(eth->h_dest,
 183                                                      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}
 215EXPORT_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 */
 222int 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}
 228EXPORT_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 * @type: Ethernet type field
 235 *
 236 * Create an Ethernet header template from the neighbour.
 237 */
 238int eth_header_cache(const struct neighbour *neigh, struct hh_cache *hh, __be16 type)
 239{
 240        struct ethhdr *eth;
 241        const struct net_device *dev = neigh->dev;
 242
 243        eth = (struct ethhdr *)
 244            (((u8 *) hh->hh_data) + (HH_DATA_OFF(sizeof(*eth))));
 245
 246        if (type == htons(ETH_P_802_3))
 247                return -1;
 248
 249        eth->h_proto = type;
 250        memcpy(eth->h_source, dev->dev_addr, ETH_ALEN);
 251        memcpy(eth->h_dest, neigh->ha, ETH_ALEN);
 252        hh->hh_len = ETH_HLEN;
 253        return 0;
 254}
 255EXPORT_SYMBOL(eth_header_cache);
 256
 257/**
 258 * eth_header_cache_update - update cache entry
 259 * @hh: destination cache entry
 260 * @dev: network device
 261 * @haddr: new hardware address
 262 *
 263 * Called by Address Resolution module to notify changes in address.
 264 */
 265void eth_header_cache_update(struct hh_cache *hh,
 266                             const struct net_device *dev,
 267                             const unsigned char *haddr)
 268{
 269        memcpy(((u8 *) hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)),
 270               haddr, ETH_ALEN);
 271}
 272EXPORT_SYMBOL(eth_header_cache_update);
 273
 274/**
 275 * eth_mac_addr - set new Ethernet hardware address
 276 * @dev: network device
 277 * @p: socket address
 278 *
 279 * Change hardware address of device.
 280 *
 281 * This doesn't change hardware matching, so needs to be overridden
 282 * for most real devices.
 283 */
 284int eth_mac_addr(struct net_device *dev, void *p)
 285{
 286        struct sockaddr *addr = p;
 287
 288        if (!(dev->priv_flags & IFF_LIVE_ADDR_CHANGE) && netif_running(dev))
 289                return -EBUSY;
 290        if (!is_valid_ether_addr(addr->sa_data))
 291                return -EADDRNOTAVAIL;
 292        memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
 293        /* if device marked as NET_ADDR_RANDOM, reset it */
 294        dev->addr_assign_type &= ~NET_ADDR_RANDOM;
 295        return 0;
 296}
 297EXPORT_SYMBOL(eth_mac_addr);
 298
 299/**
 300 * eth_change_mtu - set new MTU size
 301 * @dev: network device
 302 * @new_mtu: new Maximum Transfer Unit
 303 *
 304 * Allow changing MTU size. Needs to be overridden for devices
 305 * supporting jumbo frames.
 306 */
 307int eth_change_mtu(struct net_device *dev, int new_mtu)
 308{
 309        if (new_mtu < 68 || new_mtu > ETH_DATA_LEN)
 310                return -EINVAL;
 311        dev->mtu = new_mtu;
 312        return 0;
 313}
 314EXPORT_SYMBOL(eth_change_mtu);
 315
 316int eth_validate_addr(struct net_device *dev)
 317{
 318        if (!is_valid_ether_addr(dev->dev_addr))
 319                return -EADDRNOTAVAIL;
 320
 321        return 0;
 322}
 323EXPORT_SYMBOL(eth_validate_addr);
 324
 325const struct header_ops eth_header_ops ____cacheline_aligned = {
 326        .create         = eth_header,
 327        .parse          = eth_header_parse,
 328        .rebuild        = eth_rebuild_header,
 329        .cache          = eth_header_cache,
 330        .cache_update   = eth_header_cache_update,
 331};
 332
 333/**
 334 * ether_setup - setup Ethernet network device
 335 * @dev: network device
 336 *
 337 * Fill in the fields of the device structure with Ethernet-generic values.
 338 */
 339void ether_setup(struct net_device *dev)
 340{
 341        dev->header_ops         = &eth_header_ops;
 342        dev->type               = ARPHRD_ETHER;
 343        dev->hard_header_len    = ETH_HLEN;
 344        dev->mtu                = ETH_DATA_LEN;
 345        dev->addr_len           = ETH_ALEN;
 346        dev->tx_queue_len       = 1000; /* Ethernet wants good queues */
 347        dev->flags              = IFF_BROADCAST|IFF_MULTICAST;
 348        dev->priv_flags         |= IFF_TX_SKB_SHARING;
 349
 350        memset(dev->broadcast, 0xFF, ETH_ALEN);
 351
 352}
 353EXPORT_SYMBOL(ether_setup);
 354
 355/**
 356 * alloc_etherdev_mqs - Allocates and sets up an Ethernet device
 357 * @sizeof_priv: Size of additional driver-private structure to be allocated
 358 *      for this Ethernet device
 359 * @txqs: The number of TX queues this device has.
 360 * @rxqs: The number of RX queues this device has.
 361 *
 362 * Fill in the fields of the device structure with Ethernet-generic
 363 * values. Basically does everything except registering the device.
 364 *
 365 * Constructs a new net device, complete with a private data area of
 366 * size (sizeof_priv).  A 32-byte (not bit) alignment is enforced for
 367 * this private data area.
 368 */
 369
 370struct net_device *alloc_etherdev_mqs(int sizeof_priv, unsigned int txqs,
 371                                      unsigned int rxqs)
 372{
 373        return alloc_netdev_mqs(sizeof_priv, "eth%d", ether_setup, txqs, rxqs);
 374}
 375EXPORT_SYMBOL(alloc_etherdev_mqs);
 376
 377static size_t _format_mac_addr(char *buf, int buflen,
 378                               const unsigned char *addr, int len)
 379{
 380        int i;
 381        char *cp = buf;
 382
 383        for (i = 0; i < len; i++) {
 384                cp += scnprintf(cp, buflen - (cp - buf), "%02x", addr[i]);
 385                if (i == len - 1)
 386                        break;
 387                cp += scnprintf(cp, buflen - (cp - buf), ":");
 388        }
 389        return cp - buf;
 390}
 391
 392ssize_t sysfs_format_mac(char *buf, const unsigned char *addr, int len)
 393{
 394        size_t l;
 395
 396        l = _format_mac_addr(buf, PAGE_SIZE, addr, len);
 397        l += scnprintf(buf + l, PAGE_SIZE - l, "\n");
 398        return (ssize_t)l;
 399}
 400EXPORT_SYMBOL(sysfs_format_mac);
 401
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