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Linux/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);
402 

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