eth.c 9.28 KB
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/*
 * INET		An implementation of the TCP/IP protocol suite for the LINUX
 *		operating system.  INET is implemented using the  BSD Socket
 *		interface as the means of communication with the user level.
 *
 *		Ethernet-type device handling.
 *
 * Version:	@(#)eth.c	1.0.7	05/25/93
 *
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 * Authors:	Ross Biro
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 *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *		Mark Evans, <evansmp@uhura.aston.ac.uk>
 *		Florian  La Roche, <rzsfl@rz.uni-sb.de>
 *		Alan Cox, <gw4pts@gw4pts.ampr.org>
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 *
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 * Fixes:
 *		Mr Linux	: Arp problems
 *		Alan Cox	: Generic queue tidyup (very tiny here)
 *		Alan Cox	: eth_header ntohs should be htons
 *		Alan Cox	: eth_rebuild_header missing an htons and
 *				  minor other things.
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 *		Tegge		: Arp bug fixes.
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 *		Florian		: Removed many unnecessary functions, code cleanup
 *				  and changes for new arp and skbuff.
 *		Alan Cox	: Redid header building to reflect new format.
 *		Alan Cox	: ARP only when compiled with CONFIG_INET
 *		Greg Page	: 802.2 and SNAP stuff.
 *		Alan Cox	: MAC layer pointers/new format.
 *		Paul Gortmaker	: eth_copy_and_sum shouldn't csum padding.
 *		Alan Cox	: Protect against forwarding explosions with
 *				  older network drivers and IFF_ALLMULTI.
 *	Christer Weinigel	: Better rebuild header message.
 *             Andrew Morton    : 26Feb01: kill ether_setup() - use netdev_boot_setup().
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 */
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/ip.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/errno.h>
#include <linux/init.h>
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#include <linux/if_ether.h>
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#include <net/dst.h>
#include <net/arp.h>
#include <net/sock.h>
#include <net/ipv6.h>
#include <net/ip.h>
#include <asm/uaccess.h>
#include <asm/system.h>

__setup("ether=", netdev_boot_setup);

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/**
 * eth_header - create the Ethernet header
 * @skb:	buffer to alter
 * @dev:	source device
 * @type:	Ethernet type field
 * @daddr: destination address (NULL leave destination address)
 * @saddr: source address (NULL use device source address)
 * @len:   packet length (<= skb->len)
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 *
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 *
 * Set the protocol type. For a packet of type ETH_P_802_3 we put the length
 * in here instead. It is up to the 802.2 layer to carry protocol information.
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 */
int eth_header(struct sk_buff *skb, struct net_device *dev, unsigned short type,
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	       void *daddr, void *saddr, unsigned len)
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{
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	struct ethhdr *eth = (struct ethhdr *)skb_push(skb, ETH_HLEN);
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	if (type != ETH_P_802_3)
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		eth->h_proto = htons(type);
	else
		eth->h_proto = htons(len);

	/*
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	 *      Set the source hardware address.
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	 */
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	if (!saddr)
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		saddr = dev->dev_addr;
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	memcpy(eth->h_source, saddr, dev->addr_len);
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	if (daddr) {
		memcpy(eth->h_dest, daddr, dev->addr_len);
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		return ETH_HLEN;
	}
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	/*
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	 *      Anyway, the loopback-device should never use this function...
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	 */

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	if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
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		memset(eth->h_dest, 0, dev->addr_len);
		return ETH_HLEN;
	}
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	return -ETH_HLEN;
}

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/**
 * eth_rebuild_header- rebuild the Ethernet MAC header.
 * @skb: socket buffer to update
 *
 * This is called after an ARP or IPV6 ndisc it's resolution on this
 * sk_buff. We now let protocol (ARP) fill in the other fields.
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 *
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 * This routine CANNOT use cached dst->neigh!
 * Really, it is used only when dst->neigh is wrong.
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 */
int eth_rebuild_header(struct sk_buff *skb)
{
	struct ethhdr *eth = (struct ethhdr *)skb->data;
	struct net_device *dev = skb->dev;

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	switch (eth->h_proto) {
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#ifdef CONFIG_INET
	case __constant_htons(ETH_P_IP):
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		return arp_find(eth->h_dest, skb);
#endif
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	default:
		printk(KERN_DEBUG
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		       "%s: unable to resolve type %X addresses.\n",
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		       dev->name, (int)eth->h_proto);
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		memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
		break;
	}

	return 0;
}

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/**
 * eth_type_trans - determine the packet's protocol ID.
 * @skb: received socket data
 * @dev: receiving network device
 *
 * The rule here is that we
 * assume 802.3 if the type field is short enough to be a length.
 * This is normal practice and works for any 'now in use' protocol.
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 */
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__be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
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{
	struct ethhdr *eth;
	unsigned char *rawp;
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	skb->dev = dev;
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	skb_reset_mac_header(skb);
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	skb_pull(skb, ETH_HLEN);
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	eth = eth_hdr(skb);
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	if (is_multicast_ether_addr(eth->h_dest)) {
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		if (!compare_ether_addr(eth->h_dest, dev->broadcast))
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			skb->pkt_type = PACKET_BROADCAST;
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		else
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			skb->pkt_type = PACKET_MULTICAST;
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	}
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	/*
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	 *      This ALLMULTI check should be redundant by 1.4
	 *      so don't forget to remove it.
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	 *
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	 *      Seems, you forgot to remove it. All silly devices
	 *      seems to set IFF_PROMISC.
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	 */
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	else if (1 /*dev->flags&IFF_PROMISC */ ) {
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		if (unlikely(compare_ether_addr(eth->h_dest, dev->dev_addr)))
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			skb->pkt_type = PACKET_OTHERHOST;
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	}
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	if (ntohs(eth->h_proto) >= 1536)
		return eth->h_proto;
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	rawp = skb->data;
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	/*
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	 *      This is a magic hack to spot IPX packets. Older Novell breaks
	 *      the protocol design and runs IPX over 802.3 without an 802.2 LLC
	 *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
	 *      won't work for fault tolerant netware but does for the rest.
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	 */
	if (*(unsigned short *)rawp == 0xFFFF)
		return htons(ETH_P_802_3);
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	/*
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	 *      Real 802.2 LLC
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	 */
	return htons(ETH_P_802_2);
}
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EXPORT_SYMBOL(eth_type_trans);
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/**
 * eth_header_parse - extract hardware address from packet
 * @skb: packet to extract header from
 * @haddr: destination buffer
 */
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static int eth_header_parse(struct sk_buff *skb, unsigned char *haddr)
{
	struct ethhdr *eth = eth_hdr(skb);
	memcpy(haddr, eth->h_source, ETH_ALEN);
	return ETH_ALEN;
}

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/**
 * eth_header_cache - fill cache entry from neighbour
 * @neigh: source neighbour
 * @hh: destination cache entry
 * Create an Ethernet header template from the neighbour.
 */
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int eth_header_cache(struct neighbour *neigh, struct hh_cache *hh)
{
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	__be16 type = hh->hh_type;
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	struct ethhdr *eth;
	struct net_device *dev = neigh->dev;

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	eth = (struct ethhdr *)
	    (((u8 *) hh->hh_data) + (HH_DATA_OFF(sizeof(*eth))));
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	if (type == htons(ETH_P_802_3))
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		return -1;

	eth->h_proto = type;
	memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
	memcpy(eth->h_dest, neigh->ha, dev->addr_len);
	hh->hh_len = ETH_HLEN;
	return 0;
}

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/**
 * eth_header_cache_update - update cache entry
 * @hh: destination cache entry
 * @dev: network device
 * @haddr: new hardware address
 *
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 * Called by Address Resolution module to notify changes in address.
 */
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void eth_header_cache_update(struct hh_cache *hh, struct net_device *dev,
			     unsigned char *haddr)
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{
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	memcpy(((u8 *) hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)),
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	       haddr, dev->addr_len);
}

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/**
 * eth_mac_addr - set new Ethernet hardware address
 * @dev: network device
 * @p: socket address
 * Change hardware address of device.
 *
 * This doesn't change hardware matching, so needs to be overridden
 * for most real devices.
 */
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static int eth_mac_addr(struct net_device *dev, void *p)
{
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	struct sockaddr *addr = p;
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	if (netif_running(dev))
		return -EBUSY;
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	if (!is_valid_ether_addr(addr->sa_data))
		return -EADDRNOTAVAIL;
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	memcpy(dev->dev_addr, addr->sa_data, dev->addr_len);
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	return 0;
}

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/**
 * eth_change_mtu - set new MTU size
 * @dev: network device
 * @new_mtu: new Maximum Transfer Unit
 *
 * Allow changing MTU size. Needs to be overridden for devices
 * supporting jumbo frames.
 */
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static int eth_change_mtu(struct net_device *dev, int new_mtu)
{
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	if (new_mtu < 68 || new_mtu > ETH_DATA_LEN)
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		return -EINVAL;
	dev->mtu = new_mtu;
	return 0;
}

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/**
 * ether_setup - setup Ethernet network device
 * @dev: network device
 * Fill in the fields of the device structure with Ethernet-generic values.
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 */
void ether_setup(struct net_device *dev)
{
	dev->change_mtu		= eth_change_mtu;
	dev->hard_header	= eth_header;
	dev->rebuild_header 	= eth_rebuild_header;
	dev->set_mac_address 	= eth_mac_addr;
	dev->hard_header_cache	= eth_header_cache;
	dev->header_cache_update= eth_header_cache_update;
	dev->hard_header_parse	= eth_header_parse;

	dev->type		= ARPHRD_ETHER;
	dev->hard_header_len 	= ETH_HLEN;
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	dev->mtu		= ETH_DATA_LEN;
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	dev->addr_len		= ETH_ALEN;
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	dev->tx_queue_len	= 1000;	/* Ethernet wants good queues */
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	dev->flags		= IFF_BROADCAST|IFF_MULTICAST;
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	memset(dev->broadcast, 0xFF, ETH_ALEN);
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}
EXPORT_SYMBOL(ether_setup);

/**
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 * alloc_etherdev_mq - Allocates and sets up an Ethernet device
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 * @sizeof_priv: Size of additional driver-private structure to be allocated
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 *	for this Ethernet device
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 * @queue_count: The number of queues this device has.
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 *
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 * Fill in the fields of the device structure with Ethernet-generic
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 * values. Basically does everything except registering the device.
 *
 * Constructs a new net device, complete with a private data area of
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 * size (sizeof_priv).  A 32-byte (not bit) alignment is enforced for
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 * this private data area.
 */

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struct net_device *alloc_etherdev_mq(int sizeof_priv, unsigned int queue_count)
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{
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	return alloc_netdev_mq(sizeof_priv, "eth%d", ether_setup, queue_count);
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}
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EXPORT_SYMBOL(alloc_etherdev_mq);