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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 <net/flow_dissector.h>
 62 #include <linux/uaccess.h>
 63 
 64 __setup("ether=", netdev_boot_setup);
 65 
 66 /**
 67  * eth_header - create the Ethernet header
 68  * @skb:        buffer to alter
 69  * @dev:        source device
 70  * @type:       Ethernet type field
 71  * @daddr: destination address (NULL leave destination address)
 72  * @saddr: source address (NULL use device source address)
 73  * @len:   packet length (<= skb->len)
 74  *
 75  *
 76  * Set the protocol type. For a packet of type ETH_P_802_3/2 we put the length
 77  * in here instead.
 78  */
 79 int eth_header(struct sk_buff *skb, struct net_device *dev,
 80                unsigned short type,
 81                const void *daddr, const void *saddr, unsigned int len)
 82 {
 83         struct ethhdr *eth = (struct ethhdr *)skb_push(skb, ETH_HLEN);
 84 
 85         if (type != ETH_P_802_3 && type != ETH_P_802_2)
 86                 eth->h_proto = htons(type);
 87         else
 88                 eth->h_proto = htons(len);
 89 
 90         /*
 91          *      Set the source hardware address.
 92          */
 93 
 94         if (!saddr)
 95                 saddr = dev->dev_addr;
 96         memcpy(eth->h_source, saddr, ETH_ALEN);
 97 
 98         if (daddr) {
 99                 memcpy(eth->h_dest, daddr, ETH_ALEN);
100                 return ETH_HLEN;
101         }
102 
103         /*
104          *      Anyway, the loopback-device should never use this function...
105          */
106 
107         if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
108                 eth_zero_addr(eth->h_dest);
109                 return ETH_HLEN;
110         }
111 
112         return -ETH_HLEN;
113 }
114 EXPORT_SYMBOL(eth_header);
115 
116 /**
117  * eth_get_headlen - determine the length of header for an ethernet frame
118  * @data: pointer to start of frame
119  * @len: total length of frame
120  *
121  * Make a best effort attempt to pull the length for all of the headers for
122  * a given frame in a linear buffer.
123  */
124 u32 eth_get_headlen(void *data, unsigned int len)
125 {
126         const struct ethhdr *eth = (const struct ethhdr *)data;
127         struct flow_keys keys;
128 
129         /* this should never happen, but better safe than sorry */
130         if (unlikely(len < sizeof(*eth)))
131                 return len;
132 
133         /* parse any remaining L2/L3 headers, check for L4 */
134         if (!skb_flow_dissect_flow_keys_buf(&keys, data, eth->h_proto,
135                                             sizeof(*eth), len, 0))
136                 return max_t(u32, keys.control.thoff, sizeof(*eth));
137 
138         /* parse for any L4 headers */
139         return min_t(u32, __skb_get_poff(NULL, data, &keys, len), len);
140 }
141 EXPORT_SYMBOL(eth_get_headlen);
142 
143 /**
144  * eth_type_trans - determine the packet's protocol ID.
145  * @skb: received socket data
146  * @dev: receiving network device
147  *
148  * The rule here is that we
149  * assume 802.3 if the type field is short enough to be a length.
150  * This is normal practice and works for any 'now in use' protocol.
151  */
152 __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
153 {
154         unsigned short _service_access_point;
155         const unsigned short *sap;
156         const struct ethhdr *eth;
157 
158         skb->dev = dev;
159         skb_reset_mac_header(skb);
160 
161         eth = (struct ethhdr *)skb->data;
162         skb_pull_inline(skb, ETH_HLEN);
163 
164         if (unlikely(is_multicast_ether_addr_64bits(eth->h_dest))) {
165                 if (ether_addr_equal_64bits(eth->h_dest, dev->broadcast))
166                         skb->pkt_type = PACKET_BROADCAST;
167                 else
168                         skb->pkt_type = PACKET_MULTICAST;
169         }
170         else if (unlikely(!ether_addr_equal_64bits(eth->h_dest,
171                                                    dev->dev_addr)))
172                 skb->pkt_type = PACKET_OTHERHOST;
173 
174         /*
175          * Some variants of DSA tagging don't have an ethertype field
176          * at all, so we check here whether one of those tagging
177          * variants has been configured on the receiving interface,
178          * and if so, set skb->protocol without looking at the packet.
179          */
180         if (unlikely(netdev_uses_dsa(dev)))
181                 return htons(ETH_P_XDSA);
182 
183         if (likely(eth_proto_is_802_3(eth->h_proto)))
184                 return eth->h_proto;
185 
186         /*
187          *      This is a magic hack to spot IPX packets. Older Novell breaks
188          *      the protocol design and runs IPX over 802.3 without an 802.2 LLC
189          *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
190          *      won't work for fault tolerant netware but does for the rest.
191          */
192         sap = skb_header_pointer(skb, 0, sizeof(*sap), &_service_access_point);
193         if (sap && *sap == 0xFFFF)
194                 return htons(ETH_P_802_3);
195 
196         /*
197          *      Real 802.2 LLC
198          */
199         return htons(ETH_P_802_2);
200 }
201 EXPORT_SYMBOL(eth_type_trans);
202 
203 /**
204  * eth_header_parse - extract hardware address from packet
205  * @skb: packet to extract header from
206  * @haddr: destination buffer
207  */
208 int eth_header_parse(const struct sk_buff *skb, unsigned char *haddr)
209 {
210         const struct ethhdr *eth = eth_hdr(skb);
211         memcpy(haddr, eth->h_source, ETH_ALEN);
212         return ETH_ALEN;
213 }
214 EXPORT_SYMBOL(eth_header_parse);
215 
216 /**
217  * eth_header_cache - fill cache entry from neighbour
218  * @neigh: source neighbour
219  * @hh: destination cache entry
220  * @type: Ethernet type field
221  *
222  * Create an Ethernet header template from the neighbour.
223  */
224 int eth_header_cache(const struct neighbour *neigh, struct hh_cache *hh, __be16 type)
225 {
226         struct ethhdr *eth;
227         const struct net_device *dev = neigh->dev;
228 
229         eth = (struct ethhdr *)
230             (((u8 *) hh->hh_data) + (HH_DATA_OFF(sizeof(*eth))));
231 
232         if (type == htons(ETH_P_802_3))
233                 return -1;
234 
235         eth->h_proto = type;
236         memcpy(eth->h_source, dev->dev_addr, ETH_ALEN);
237         memcpy(eth->h_dest, neigh->ha, ETH_ALEN);
238         hh->hh_len = ETH_HLEN;
239         return 0;
240 }
241 EXPORT_SYMBOL(eth_header_cache);
242 
243 /**
244  * eth_header_cache_update - update cache entry
245  * @hh: destination cache entry
246  * @dev: network device
247  * @haddr: new hardware address
248  *
249  * Called by Address Resolution module to notify changes in address.
250  */
251 void eth_header_cache_update(struct hh_cache *hh,
252                              const struct net_device *dev,
253                              const unsigned char *haddr)
254 {
255         memcpy(((u8 *) hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)),
256                haddr, ETH_ALEN);
257 }
258 EXPORT_SYMBOL(eth_header_cache_update);
259 
260 /**
261  * eth_prepare_mac_addr_change - prepare for mac change
262  * @dev: network device
263  * @p: socket address
264  */
265 int eth_prepare_mac_addr_change(struct net_device *dev, void *p)
266 {
267         struct sockaddr *addr = p;
268 
269         if (!(dev->priv_flags & IFF_LIVE_ADDR_CHANGE) && netif_running(dev))
270                 return -EBUSY;
271         if (!is_valid_ether_addr(addr->sa_data))
272                 return -EADDRNOTAVAIL;
273         return 0;
274 }
275 EXPORT_SYMBOL(eth_prepare_mac_addr_change);
276 
277 /**
278  * eth_commit_mac_addr_change - commit mac change
279  * @dev: network device
280  * @p: socket address
281  */
282 void eth_commit_mac_addr_change(struct net_device *dev, void *p)
283 {
284         struct sockaddr *addr = p;
285 
286         memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
287 }
288 EXPORT_SYMBOL(eth_commit_mac_addr_change);
289 
290 /**
291  * eth_mac_addr - set new Ethernet hardware address
292  * @dev: network device
293  * @p: socket address
294  *
295  * Change hardware address of device.
296  *
297  * This doesn't change hardware matching, so needs to be overridden
298  * for most real devices.
299  */
300 int eth_mac_addr(struct net_device *dev, void *p)
301 {
302         int ret;
303 
304         ret = eth_prepare_mac_addr_change(dev, p);
305         if (ret < 0)
306                 return ret;
307         eth_commit_mac_addr_change(dev, p);
308         return 0;
309 }
310 EXPORT_SYMBOL(eth_mac_addr);
311 
312 /**
313  * eth_change_mtu - set new MTU size
314  * @dev: network device
315  * @new_mtu: new Maximum Transfer Unit
316  *
317  * Allow changing MTU size. Needs to be overridden for devices
318  * supporting jumbo frames.
319  */
320 int eth_change_mtu(struct net_device *dev, int new_mtu)
321 {
322         if (new_mtu < 68 || new_mtu > ETH_DATA_LEN)
323                 return -EINVAL;
324         dev->mtu = new_mtu;
325         return 0;
326 }
327 EXPORT_SYMBOL(eth_change_mtu);
328 
329 int eth_validate_addr(struct net_device *dev)
330 {
331         if (!is_valid_ether_addr(dev->dev_addr))
332                 return -EADDRNOTAVAIL;
333 
334         return 0;
335 }
336 EXPORT_SYMBOL(eth_validate_addr);
337 
338 const struct header_ops eth_header_ops ____cacheline_aligned = {
339         .create         = eth_header,
340         .parse          = eth_header_parse,
341         .cache          = eth_header_cache,
342         .cache_update   = eth_header_cache_update,
343 };
344 
345 /**
346  * ether_setup - setup Ethernet network device
347  * @dev: network device
348  *
349  * Fill in the fields of the device structure with Ethernet-generic values.
350  */
351 void ether_setup(struct net_device *dev)
352 {
353         dev->header_ops         = &eth_header_ops;
354         dev->type               = ARPHRD_ETHER;
355         dev->hard_header_len    = ETH_HLEN;
356         dev->mtu                = ETH_DATA_LEN;
357         dev->addr_len           = ETH_ALEN;
358         dev->tx_queue_len       = 1000; /* Ethernet wants good queues */
359         dev->flags              = IFF_BROADCAST|IFF_MULTICAST;
360         dev->priv_flags         |= IFF_TX_SKB_SHARING;
361 
362         eth_broadcast_addr(dev->broadcast);
363 
364 }
365 EXPORT_SYMBOL(ether_setup);
366 
367 /**
368  * alloc_etherdev_mqs - Allocates and sets up an Ethernet device
369  * @sizeof_priv: Size of additional driver-private structure to be allocated
370  *      for this Ethernet device
371  * @txqs: The number of TX queues this device has.
372  * @rxqs: The number of RX queues this device has.
373  *
374  * Fill in the fields of the device structure with Ethernet-generic
375  * values. Basically does everything except registering the device.
376  *
377  * Constructs a new net device, complete with a private data area of
378  * size (sizeof_priv).  A 32-byte (not bit) alignment is enforced for
379  * this private data area.
380  */
381 
382 struct net_device *alloc_etherdev_mqs(int sizeof_priv, unsigned int txqs,
383                                       unsigned int rxqs)
384 {
385         return alloc_netdev_mqs(sizeof_priv, "eth%d", NET_NAME_UNKNOWN,
386                                 ether_setup, txqs, rxqs);
387 }
388 EXPORT_SYMBOL(alloc_etherdev_mqs);
389 
390 ssize_t sysfs_format_mac(char *buf, const unsigned char *addr, int len)
391 {
392         return scnprintf(buf, PAGE_SIZE, "%*phC\n", len, addr);
393 }
394 EXPORT_SYMBOL(sysfs_format_mac);
395 
396 struct sk_buff **eth_gro_receive(struct sk_buff **head,
397                                  struct sk_buff *skb)
398 {
399         struct sk_buff *p, **pp = NULL;
400         struct ethhdr *eh, *eh2;
401         unsigned int hlen, off_eth;
402         const struct packet_offload *ptype;
403         __be16 type;
404         int flush = 1;
405 
406         off_eth = skb_gro_offset(skb);
407         hlen = off_eth + sizeof(*eh);
408         eh = skb_gro_header_fast(skb, off_eth);
409         if (skb_gro_header_hard(skb, hlen)) {
410                 eh = skb_gro_header_slow(skb, hlen, off_eth);
411                 if (unlikely(!eh))
412                         goto out;
413         }
414 
415         flush = 0;
416 
417         for (p = *head; p; p = p->next) {
418                 if (!NAPI_GRO_CB(p)->same_flow)
419                         continue;
420 
421                 eh2 = (struct ethhdr *)(p->data + off_eth);
422                 if (compare_ether_header(eh, eh2)) {
423                         NAPI_GRO_CB(p)->same_flow = 0;
424                         continue;
425                 }
426         }
427 
428         type = eh->h_proto;
429 
430         rcu_read_lock();
431         ptype = gro_find_receive_by_type(type);
432         if (ptype == NULL) {
433                 flush = 1;
434                 goto out_unlock;
435         }
436 
437         skb_gro_pull(skb, sizeof(*eh));
438         skb_gro_postpull_rcsum(skb, eh, sizeof(*eh));
439         pp = ptype->callbacks.gro_receive(head, skb);
440 
441 out_unlock:
442         rcu_read_unlock();
443 out:
444         NAPI_GRO_CB(skb)->flush |= flush;
445 
446         return pp;
447 }
448 EXPORT_SYMBOL(eth_gro_receive);
449 
450 int eth_gro_complete(struct sk_buff *skb, int nhoff)
451 {
452         struct ethhdr *eh = (struct ethhdr *)(skb->data + nhoff);
453         __be16 type = eh->h_proto;
454         struct packet_offload *ptype;
455         int err = -ENOSYS;
456 
457         if (skb->encapsulation)
458                 skb_set_inner_mac_header(skb, nhoff);
459 
460         rcu_read_lock();
461         ptype = gro_find_complete_by_type(type);
462         if (ptype != NULL)
463                 err = ptype->callbacks.gro_complete(skb, nhoff +
464                                                     sizeof(struct ethhdr));
465 
466         rcu_read_unlock();
467         return err;
468 }
469 EXPORT_SYMBOL(eth_gro_complete);
470 
471 static struct packet_offload eth_packet_offload __read_mostly = {
472         .type = cpu_to_be16(ETH_P_TEB),
473         .priority = 10,
474         .callbacks = {
475                 .gro_receive = eth_gro_receive,
476                 .gro_complete = eth_gro_complete,
477         },
478 };
479 
480 static int __init eth_offload_init(void)
481 {
482         dev_add_offload(&eth_packet_offload);
483 
484         return 0;
485 }
486 
487 fs_initcall(eth_offload_init);
488 

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