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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_get_headlen - determine the the length of header for an ethernet frame
150  * @data: pointer to start of frame
151  * @len: total length of frame
152  *
153  * Make a best effort attempt to pull the length for all of the headers for
154  * a given frame in a linear buffer.
155  */
156 u32 eth_get_headlen(void *data, unsigned int len)
157 {
158         const struct ethhdr *eth = (const struct ethhdr *)data;
159         struct flow_keys keys;
160 
161         /* this should never happen, but better safe than sorry */
162         if (len < sizeof(*eth))
163                 return len;
164 
165         /* parse any remaining L2/L3 headers, check for L4 */
166         if (!__skb_flow_dissect(NULL, &keys, data,
167                                 eth->h_proto, sizeof(*eth), len))
168                 return max_t(u32, keys.thoff, sizeof(*eth));
169 
170         /* parse for any L4 headers */
171         return min_t(u32, __skb_get_poff(NULL, data, &keys, len), len);
172 }
173 EXPORT_SYMBOL(eth_get_headlen);
174 
175 /**
176  * eth_type_trans - determine the packet's protocol ID.
177  * @skb: received socket data
178  * @dev: receiving network device
179  *
180  * The rule here is that we
181  * assume 802.3 if the type field is short enough to be a length.
182  * This is normal practice and works for any 'now in use' protocol.
183  */
184 __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
185 {
186         unsigned short _service_access_point;
187         const unsigned short *sap;
188         const struct ethhdr *eth;
189 
190         skb->dev = dev;
191         skb_reset_mac_header(skb);
192         skb_pull_inline(skb, ETH_HLEN);
193         eth = eth_hdr(skb);
194 
195         if (unlikely(is_multicast_ether_addr(eth->h_dest))) {
196                 if (ether_addr_equal_64bits(eth->h_dest, dev->broadcast))
197                         skb->pkt_type = PACKET_BROADCAST;
198                 else
199                         skb->pkt_type = PACKET_MULTICAST;
200         }
201         else if (unlikely(!ether_addr_equal_64bits(eth->h_dest,
202                                                    dev->dev_addr)))
203                 skb->pkt_type = PACKET_OTHERHOST;
204 
205         /*
206          * Some variants of DSA tagging don't have an ethertype field
207          * at all, so we check here whether one of those tagging
208          * variants has been configured on the receiving interface,
209          * and if so, set skb->protocol without looking at the packet.
210          */
211         if (unlikely(netdev_uses_dsa(dev)))
212                 return htons(ETH_P_XDSA);
213 
214         if (likely(ntohs(eth->h_proto) >= ETH_P_802_3_MIN))
215                 return eth->h_proto;
216 
217         /*
218          *      This is a magic hack to spot IPX packets. Older Novell breaks
219          *      the protocol design and runs IPX over 802.3 without an 802.2 LLC
220          *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
221          *      won't work for fault tolerant netware but does for the rest.
222          */
223         sap = skb_header_pointer(skb, 0, sizeof(*sap), &_service_access_point);
224         if (sap && *sap == 0xFFFF)
225                 return htons(ETH_P_802_3);
226 
227         /*
228          *      Real 802.2 LLC
229          */
230         return htons(ETH_P_802_2);
231 }
232 EXPORT_SYMBOL(eth_type_trans);
233 
234 /**
235  * eth_header_parse - extract hardware address from packet
236  * @skb: packet to extract header from
237  * @haddr: destination buffer
238  */
239 int eth_header_parse(const struct sk_buff *skb, unsigned char *haddr)
240 {
241         const struct ethhdr *eth = eth_hdr(skb);
242         memcpy(haddr, eth->h_source, ETH_ALEN);
243         return ETH_ALEN;
244 }
245 EXPORT_SYMBOL(eth_header_parse);
246 
247 /**
248  * eth_header_cache - fill cache entry from neighbour
249  * @neigh: source neighbour
250  * @hh: destination cache entry
251  * @type: Ethernet type field
252  *
253  * Create an Ethernet header template from the neighbour.
254  */
255 int eth_header_cache(const struct neighbour *neigh, struct hh_cache *hh, __be16 type)
256 {
257         struct ethhdr *eth;
258         const struct net_device *dev = neigh->dev;
259 
260         eth = (struct ethhdr *)
261             (((u8 *) hh->hh_data) + (HH_DATA_OFF(sizeof(*eth))));
262 
263         if (type == htons(ETH_P_802_3))
264                 return -1;
265 
266         eth->h_proto = type;
267         memcpy(eth->h_source, dev->dev_addr, ETH_ALEN);
268         memcpy(eth->h_dest, neigh->ha, ETH_ALEN);
269         hh->hh_len = ETH_HLEN;
270         return 0;
271 }
272 EXPORT_SYMBOL(eth_header_cache);
273 
274 /**
275  * eth_header_cache_update - update cache entry
276  * @hh: destination cache entry
277  * @dev: network device
278  * @haddr: new hardware address
279  *
280  * Called by Address Resolution module to notify changes in address.
281  */
282 void eth_header_cache_update(struct hh_cache *hh,
283                              const struct net_device *dev,
284                              const unsigned char *haddr)
285 {
286         memcpy(((u8 *) hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)),
287                haddr, ETH_ALEN);
288 }
289 EXPORT_SYMBOL(eth_header_cache_update);
290 
291 /**
292  * eth_prepare_mac_addr_change - prepare for mac change
293  * @dev: network device
294  * @p: socket address
295  */
296 int eth_prepare_mac_addr_change(struct net_device *dev, void *p)
297 {
298         struct sockaddr *addr = p;
299 
300         if (!(dev->priv_flags & IFF_LIVE_ADDR_CHANGE) && netif_running(dev))
301                 return -EBUSY;
302         if (!is_valid_ether_addr(addr->sa_data))
303                 return -EADDRNOTAVAIL;
304         return 0;
305 }
306 EXPORT_SYMBOL(eth_prepare_mac_addr_change);
307 
308 /**
309  * eth_commit_mac_addr_change - commit mac change
310  * @dev: network device
311  * @p: socket address
312  */
313 void eth_commit_mac_addr_change(struct net_device *dev, void *p)
314 {
315         struct sockaddr *addr = p;
316 
317         memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
318 }
319 EXPORT_SYMBOL(eth_commit_mac_addr_change);
320 
321 /**
322  * eth_mac_addr - set new Ethernet hardware address
323  * @dev: network device
324  * @p: socket address
325  *
326  * Change hardware address of device.
327  *
328  * This doesn't change hardware matching, so needs to be overridden
329  * for most real devices.
330  */
331 int eth_mac_addr(struct net_device *dev, void *p)
332 {
333         int ret;
334 
335         ret = eth_prepare_mac_addr_change(dev, p);
336         if (ret < 0)
337                 return ret;
338         eth_commit_mac_addr_change(dev, p);
339         return 0;
340 }
341 EXPORT_SYMBOL(eth_mac_addr);
342 
343 /**
344  * eth_change_mtu - set new MTU size
345  * @dev: network device
346  * @new_mtu: new Maximum Transfer Unit
347  *
348  * Allow changing MTU size. Needs to be overridden for devices
349  * supporting jumbo frames.
350  */
351 int eth_change_mtu(struct net_device *dev, int new_mtu)
352 {
353         if (new_mtu < 68 || new_mtu > ETH_DATA_LEN)
354                 return -EINVAL;
355         dev->mtu = new_mtu;
356         return 0;
357 }
358 EXPORT_SYMBOL(eth_change_mtu);
359 
360 int eth_validate_addr(struct net_device *dev)
361 {
362         if (!is_valid_ether_addr(dev->dev_addr))
363                 return -EADDRNOTAVAIL;
364 
365         return 0;
366 }
367 EXPORT_SYMBOL(eth_validate_addr);
368 
369 const struct header_ops eth_header_ops ____cacheline_aligned = {
370         .create         = eth_header,
371         .parse          = eth_header_parse,
372         .rebuild        = eth_rebuild_header,
373         .cache          = eth_header_cache,
374         .cache_update   = eth_header_cache_update,
375 };
376 
377 /**
378  * ether_setup - setup Ethernet network device
379  * @dev: network device
380  *
381  * Fill in the fields of the device structure with Ethernet-generic values.
382  */
383 void ether_setup(struct net_device *dev)
384 {
385         dev->header_ops         = &eth_header_ops;
386         dev->type               = ARPHRD_ETHER;
387         dev->hard_header_len    = ETH_HLEN;
388         dev->mtu                = ETH_DATA_LEN;
389         dev->addr_len           = ETH_ALEN;
390         dev->tx_queue_len       = 1000; /* Ethernet wants good queues */
391         dev->flags              = IFF_BROADCAST|IFF_MULTICAST;
392         dev->priv_flags         |= IFF_TX_SKB_SHARING;
393 
394         memset(dev->broadcast, 0xFF, ETH_ALEN);
395 
396 }
397 EXPORT_SYMBOL(ether_setup);
398 
399 /**
400  * alloc_etherdev_mqs - Allocates and sets up an Ethernet device
401  * @sizeof_priv: Size of additional driver-private structure to be allocated
402  *      for this Ethernet device
403  * @txqs: The number of TX queues this device has.
404  * @rxqs: The number of RX queues this device has.
405  *
406  * Fill in the fields of the device structure with Ethernet-generic
407  * values. Basically does everything except registering the device.
408  *
409  * Constructs a new net device, complete with a private data area of
410  * size (sizeof_priv).  A 32-byte (not bit) alignment is enforced for
411  * this private data area.
412  */
413 
414 struct net_device *alloc_etherdev_mqs(int sizeof_priv, unsigned int txqs,
415                                       unsigned int rxqs)
416 {
417         return alloc_netdev_mqs(sizeof_priv, "eth%d", NET_NAME_UNKNOWN,
418                                 ether_setup, txqs, rxqs);
419 }
420 EXPORT_SYMBOL(alloc_etherdev_mqs);
421 
422 ssize_t sysfs_format_mac(char *buf, const unsigned char *addr, int len)
423 {
424         return scnprintf(buf, PAGE_SIZE, "%*phC\n", len, addr);
425 }
426 EXPORT_SYMBOL(sysfs_format_mac);
427 

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