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 <linux/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  */
  78 int 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 }
 113 EXPORT_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  */
 125 int 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                 netdev_dbg(dev,
 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 }
 146 EXPORT_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         unsigned short _service_access_point;
 160         const unsigned short *sap;
 161         const struct ethhdr *eth;
 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 (ether_addr_equal_64bits(eth->h_dest, dev->broadcast))
 170                         skb->pkt_type = PACKET_BROADCAST;
 171                 else
 172                         skb->pkt_type = PACKET_MULTICAST;
 173         }
 174         else if (unlikely(!ether_addr_equal_64bits(eth->h_dest,
 175                                                    dev->dev_addr)))
 176                 skb->pkt_type = PACKET_OTHERHOST;
 177
 178         /*
 179          * Some variants of DSA tagging don't have an ethertype field
 180          * at all, so we check here whether one of those tagging
 181          * variants has been configured on the receiving interface,
 182          * and if so, set skb->protocol without looking at the packet.
 183          */
 184         if (unlikely(netdev_uses_dsa_tags(dev)))
 185                 return htons(ETH_P_DSA);
 186
 187         if (unlikely(netdev_uses_trailer_tags(dev)))
 188                 return htons(ETH_P_TRAILER);
 189
 190         if (likely(ntohs(eth->h_proto) >= ETH_P_802_3_MIN))
 191                 return eth->h_proto;
 192
 193         /*
 194          *      This is a magic hack to spot IPX packets. Older Novell breaks
 195          *      the protocol design and runs IPX over 802.3 without an 802.2 LLC
 196          *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
 197          *      won't work for fault tolerant netware but does for the rest.
 198          */
 199         sap = skb_header_pointer(skb, 0, sizeof(*sap), &_service_access_point);
 200         if (sap && *sap == 0xFFFF)
 201                 return htons(ETH_P_802_3);
 202
 203         /*
 204          *      Real 802.2 LLC
 205          */
 206         return htons(ETH_P_802_2);
 207 }
 208 EXPORT_SYMBOL(eth_type_trans);
 209
 210 /**
 211  * eth_header_parse - extract hardware address from packet
 212  * @skb: packet to extract header from
 213  * @haddr: destination buffer
 214  */
 215 int eth_header_parse(const struct sk_buff *skb, unsigned char *haddr)
 216 {
 217         const struct ethhdr *eth = eth_hdr(skb);
 218         memcpy(haddr, eth->h_source, ETH_ALEN);
 219         return ETH_ALEN;
 220 }
 221 EXPORT_SYMBOL(eth_header_parse);
 222
 223 /**
 224  * eth_header_cache - fill cache entry from neighbour
 225  * @neigh: source neighbour
 226  * @hh: destination cache entry
 227  * @type: Ethernet type field
 228  *
 229  * Create an Ethernet header template from the neighbour.
 230  */
 231 int eth_header_cache(const struct neighbour *neigh, struct hh_cache *hh, __be16 type)
 232 {
 233         struct ethhdr *eth;
 234         const struct net_device *dev = neigh->dev;
 235
 236         eth = (struct ethhdr *)
 237             (((u8 *) hh->hh_data) + (HH_DATA_OFF(sizeof(*eth))));
 238
 239         if (type == htons(ETH_P_802_3))
 240                 return -1;
 241
 242         eth->h_proto = type;
 243         memcpy(eth->h_source, dev->dev_addr, ETH_ALEN);
 244         memcpy(eth->h_dest, neigh->ha, ETH_ALEN);
 245         hh->hh_len = ETH_HLEN;
 246         return 0;
 247 }
 248 EXPORT_SYMBOL(eth_header_cache);
 249
 250 /**
 251  * eth_header_cache_update - update cache entry
 252  * @hh: destination cache entry
 253  * @dev: network device
 254  * @haddr: new hardware address
 255  *
 256  * Called by Address Resolution module to notify changes in address.
 257  */
 258 void eth_header_cache_update(struct hh_cache *hh,
 259                              const struct net_device *dev,
 260                              const unsigned char *haddr)
 261 {
 262         memcpy(((u8 *) hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)),
 263                haddr, ETH_ALEN);
 264 }
 265 EXPORT_SYMBOL(eth_header_cache_update);
 266
 267 /**
 268  * eth_prepare_mac_addr_change - prepare for mac change
 269  * @dev: network device
 270  * @p: socket address
 271  */
 272 int eth_prepare_mac_addr_change(struct net_device *dev, void *p)
 273 {
 274         struct sockaddr *addr = p;
 275
 276         if (!(dev->priv_flags & IFF_LIVE_ADDR_CHANGE) && netif_running(dev))
 277                 return -EBUSY;
 278         if (!is_valid_ether_addr(addr->sa_data))
 279                 return -EADDRNOTAVAIL;
 280         return 0;
 281 }
 282 EXPORT_SYMBOL(eth_prepare_mac_addr_change);
 283
 284 /**
 285  * eth_commit_mac_addr_change - commit mac change
 286  * @dev: network device
 287  * @p: socket address
 288  */
 289 void eth_commit_mac_addr_change(struct net_device *dev, void *p)
 290 {
 291         struct sockaddr *addr = p;
 292
 293         memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
 294 }
 295 EXPORT_SYMBOL(eth_commit_mac_addr_change);
 296
 297 /**
 298  * eth_mac_addr - set new Ethernet hardware address
 299  * @dev: network device
 300  * @p: socket address
 301  *
 302  * Change hardware address of device.
 303  *
 304  * This doesn't change hardware matching, so needs to be overridden
 305  * for most real devices.
 306  */
 307 int eth_mac_addr(struct net_device *dev, void *p)
 308 {
 309         int ret;
 310
 311         ret = eth_prepare_mac_addr_change(dev, p);
 312         if (ret < 0)
 313                 return ret;
 314         eth_commit_mac_addr_change(dev, p);
 315         return 0;
 316 }
 317 EXPORT_SYMBOL(eth_mac_addr);
 318
 319 /**
 320  * eth_change_mtu - set new MTU size
 321  * @dev: network device
 322  * @new_mtu: new Maximum Transfer Unit
 323  *
 324  * Allow changing MTU size. Needs to be overridden for devices
 325  * supporting jumbo frames.
 326  */
 327 int eth_change_mtu(struct net_device *dev, int new_mtu)
 328 {
 329         if (new_mtu < 68 || new_mtu > ETH_DATA_LEN)
 330                 return -EINVAL;
 331         dev->mtu = new_mtu;
 332         return 0;
 333 }
 334 EXPORT_SYMBOL(eth_change_mtu);
 335
 336 int eth_validate_addr(struct net_device *dev)
 337 {
 338         if (!is_valid_ether_addr(dev->dev_addr))
 339                 return -EADDRNOTAVAIL;
 340
 341         return 0;
 342 }
 343 EXPORT_SYMBOL(eth_validate_addr);
 344
 345 const struct header_ops eth_header_ops ____cacheline_aligned = {
 346         .create         = eth_header,
 347         .parse          = eth_header_parse,
 348         .rebuild        = eth_rebuild_header,
 349         .cache          = eth_header_cache,
 350         .cache_update   = eth_header_cache_update,
 351 };
 352
 353 /**
 354  * ether_setup - setup Ethernet network device
 355  * @dev: network device
 356  *
 357  * Fill in the fields of the device structure with Ethernet-generic values.
 358  */
 359 void ether_setup(struct net_device *dev)
 360 {
 361         dev->header_ops         = &eth_header_ops;
 362         dev->type               = ARPHRD_ETHER;
 363         dev->hard_header_len    = ETH_HLEN;
 364         dev->mtu                = ETH_DATA_LEN;
 365         dev->addr_len           = ETH_ALEN;
 366         dev->tx_queue_len       = 1000; /* Ethernet wants good queues */
 367         dev->flags              = IFF_BROADCAST|IFF_MULTICAST;
 368         dev->priv_flags         |= IFF_TX_SKB_SHARING;
 369
 370         memset(dev->broadcast, 0xFF, ETH_ALEN);
 371
 372 }
 373 EXPORT_SYMBOL(ether_setup);
 374
 375 /**
 376  * alloc_etherdev_mqs - Allocates and sets up an Ethernet device
 377  * @sizeof_priv: Size of additional driver-private structure to be allocated
 378  *      for this Ethernet device
 379  * @txqs: The number of TX queues this device has.
 380  * @rxqs: The number of RX queues this device has.
 381  *
 382  * Fill in the fields of the device structure with Ethernet-generic
 383  * values. Basically does everything except registering the device.
 384  *
 385  * Constructs a new net device, complete with a private data area of
 386  * size (sizeof_priv).  A 32-byte (not bit) alignment is enforced for
 387  * this private data area.
 388  */
 389
 390 struct net_device *alloc_etherdev_mqs(int sizeof_priv, unsigned int txqs,
 391                                       unsigned int rxqs)
 392 {
 393         return alloc_netdev_mqs(sizeof_priv, "eth%d", ether_setup, txqs, rxqs);
 394 }
 395 EXPORT_SYMBOL(alloc_etherdev_mqs);
 396
 397 ssize_t sysfs_format_mac(char *buf, const unsigned char *addr, int len)
 398 {
 399         return scnprintf(buf, PAGE_SIZE, "%*phC\n", len, addr);
 400 }
 401 EXPORT_SYMBOL(sysfs_format_mac);