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 <asm/uaccess.h>
 61 #include <asm/system.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 we put the length
 76  * in here instead. It is up to the 802.2 layer to carry protocol information.
 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 len)
 81 {
 82 	struct ethhdr *eth = (struct ethhdr *)skb_push(skb, ETH_HLEN);
 83 
 84 	if (type != ETH_P_802_3)
 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 __constant_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, (int)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 	struct ethhdr *eth;
160 	unsigned char *rawp;
161 
162 	skb->dev = dev;
163 	skb_reset_mac_header(skb);
164 	skb_pull(skb, ETH_HLEN);
165 	eth = eth_hdr(skb);
166 
167 	if (is_multicast_ether_addr(eth->h_dest)) {
168 		if (!compare_ether_addr(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(eth->h_dest, dev->dev_addr)))
184 			skb->pkt_type = PACKET_OTHERHOST;
185 	}
186 
187 	if (ntohs(eth->h_proto) >= 1536)
188 		return eth->h_proto;
189 
190 	rawp = skb->data;
191 
192 	/*
193 	 *      This is a magic hack to spot IPX packets. Older Novell breaks
194 	 *      the protocol design and runs IPX over 802.3 without an 802.2 LLC
195 	 *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
196 	 *      won't work for fault tolerant netware but does for the rest.
197 	 */
198 	if (*(unsigned short *)rawp == 0xFFFF)
199 		return htons(ETH_P_802_3);
200 
201 	/*
202 	 *      Real 802.2 LLC
203 	 */
204 	return htons(ETH_P_802_2);
205 }
206 EXPORT_SYMBOL(eth_type_trans);
207 
208 /**
209  * eth_header_parse - extract hardware address from packet
210  * @skb: packet to extract header from
211  * @haddr: destination buffer
212  */
213 int eth_header_parse(const struct sk_buff *skb, unsigned char *haddr)
214 {
215 	const struct ethhdr *eth = eth_hdr(skb);
216 	memcpy(haddr, eth->h_source, ETH_ALEN);
217 	return ETH_ALEN;
218 }
219 EXPORT_SYMBOL(eth_header_parse);
220 
221 /**
222  * eth_header_cache - fill cache entry from neighbour
223  * @neigh: source neighbour
224  * @hh: destination cache entry
225  * Create an Ethernet header template from the neighbour.
226  */
227 int eth_header_cache(const struct neighbour *neigh, struct hh_cache *hh)
228 {
229 	__be16 type = hh->hh_type;
230 	struct ethhdr *eth;
231 	const struct net_device *dev = neigh->dev;
232 
233 	eth = (struct ethhdr *)
234 	    (((u8 *) hh->hh_data) + (HH_DATA_OFF(sizeof(*eth))));
235 
236 	if (type == htons(ETH_P_802_3))
237 		return -1;
238 
239 	eth->h_proto = type;
240 	memcpy(eth->h_source, dev->dev_addr, ETH_ALEN);
241 	memcpy(eth->h_dest, neigh->ha, ETH_ALEN);
242 	hh->hh_len = ETH_HLEN;
243 	return 0;
244 }
245 EXPORT_SYMBOL(eth_header_cache);
246 
247 /**
248  * eth_header_cache_update - update cache entry
249  * @hh: destination cache entry
250  * @dev: network device
251  * @haddr: new hardware address
252  *
253  * Called by Address Resolution module to notify changes in address.
254  */
255 void eth_header_cache_update(struct hh_cache *hh,
256 			     const struct net_device *dev,
257 			     const unsigned char *haddr)
258 {
259 	memcpy(((u8 *) hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)),
260 	       haddr, ETH_ALEN);
261 }
262 EXPORT_SYMBOL(eth_header_cache_update);
263 
264 /**
265  * eth_mac_addr - set new Ethernet hardware address
266  * @dev: network device
267  * @p: socket address
268  * Change hardware address of device.
269  *
270  * This doesn't change hardware matching, so needs to be overridden
271  * for most real devices.
272  */
273 static int eth_mac_addr(struct net_device *dev, void *p)
274 {
275 	struct sockaddr *addr = p;
276 
277 	if (netif_running(dev))
278 		return -EBUSY;
279 	if (!is_valid_ether_addr(addr->sa_data))
280 		return -EADDRNOTAVAIL;
281 	memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
282 	return 0;
283 }
284 
285 /**
286  * eth_change_mtu - set new MTU size
287  * @dev: network device
288  * @new_mtu: new Maximum Transfer Unit
289  *
290  * Allow changing MTU size. Needs to be overridden for devices
291  * supporting jumbo frames.
292  */
293 static int eth_change_mtu(struct net_device *dev, int new_mtu)
294 {
295 	if (new_mtu < 68 || new_mtu > ETH_DATA_LEN)
296 		return -EINVAL;
297 	dev->mtu = new_mtu;
298 	return 0;
299 }
300 
301 static int eth_validate_addr(struct net_device *dev)
302 {
303 	if (!is_valid_ether_addr(dev->dev_addr))
304 		return -EINVAL;
305 
306 	return 0;
307 }
308 
309 const struct header_ops eth_header_ops ____cacheline_aligned = {
310 	.create		= eth_header,
311 	.parse		= eth_header_parse,
312 	.rebuild	= eth_rebuild_header,
313 	.cache		= eth_header_cache,
314 	.cache_update	= eth_header_cache_update,
315 };
316 
317 /**
318  * ether_setup - setup Ethernet network device
319  * @dev: network device
320  * Fill in the fields of the device structure with Ethernet-generic values.
321  */
322 void ether_setup(struct net_device *dev)
323 {
324 	dev->header_ops		= &eth_header_ops;
325 
326 	dev->change_mtu		= eth_change_mtu;
327 	dev->set_mac_address 	= eth_mac_addr;
328 	dev->validate_addr	= eth_validate_addr;
329 
330 	dev->type		= ARPHRD_ETHER;
331 	dev->hard_header_len 	= ETH_HLEN;
332 	dev->mtu		= ETH_DATA_LEN;
333 	dev->addr_len		= ETH_ALEN;
334 	dev->tx_queue_len	= 1000;	/* Ethernet wants good queues */
335 	dev->flags		= IFF_BROADCAST|IFF_MULTICAST;
336 
337 	memset(dev->broadcast, 0xFF, ETH_ALEN);
338 
339 }
340 EXPORT_SYMBOL(ether_setup);
341 
342 /**
343  * alloc_etherdev_mq - Allocates and sets up an Ethernet device
344  * @sizeof_priv: Size of additional driver-private structure to be allocated
345  *	for this Ethernet device
346  * @queue_count: The number of queues this device has.
347  *
348  * Fill in the fields of the device structure with Ethernet-generic
349  * values. Basically does everything except registering the device.
350  *
351  * Constructs a new net device, complete with a private data area of
352  * size (sizeof_priv).  A 32-byte (not bit) alignment is enforced for
353  * this private data area.
354  */
355 
356 struct net_device *alloc_etherdev_mq(int sizeof_priv, unsigned int queue_count)
357 {
358 	return alloc_netdev_mq(sizeof_priv, "eth%d", ether_setup, queue_count);
359 }
360 EXPORT_SYMBOL(alloc_etherdev_mq);
361 
362 char *print_mac(char *buf, const u8 *addr)
363 {
364 	sprintf(buf, MAC_FMT,
365 		addr[0], addr[1], addr[2], addr[3], addr[4], addr[5]);
366 	return buf;
367 }
368 EXPORT_SYMBOL(print_mac);