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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                 eth_zero_addr(eth->h_dest);
108                 return ETH_HLEN;
109         }
110 
111         return -ETH_HLEN;
112 }
113 EXPORT_SYMBOL(eth_header);
114 
115 /**
116  * eth_get_headlen - determine the the length of header for an ethernet frame
117  * @data: pointer to start of frame
118  * @len: total length of frame
119  *
120  * Make a best effort attempt to pull the length for all of the headers for
121  * a given frame in a linear buffer.
122  */
123 u32 eth_get_headlen(void *data, unsigned int len)
124 {
125         const struct ethhdr *eth = (const struct ethhdr *)data;
126         struct flow_keys keys;
127 
128         /* this should never happen, but better safe than sorry */
129         if (len < sizeof(*eth))
130                 return len;
131 
132         /* parse any remaining L2/L3 headers, check for L4 */
133         if (!__skb_flow_dissect(NULL, &keys, data,
134                                 eth->h_proto, sizeof(*eth), len))
135                 return max_t(u32, keys.thoff, sizeof(*eth));
136 
137         /* parse for any L4 headers */
138         return min_t(u32, __skb_get_poff(NULL, data, &keys, len), len);
139 }
140 EXPORT_SYMBOL(eth_get_headlen);
141 
142 /**
143  * eth_type_trans - determine the packet's protocol ID.
144  * @skb: received socket data
145  * @dev: receiving network device
146  *
147  * The rule here is that we
148  * assume 802.3 if the type field is short enough to be a length.
149  * This is normal practice and works for any 'now in use' protocol.
150  */
151 __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
152 {
153         unsigned short _service_access_point;
154         const unsigned short *sap;
155         const struct ethhdr *eth;
156 
157         skb->dev = dev;
158         skb_reset_mac_header(skb);
159         skb_pull_inline(skb, ETH_HLEN);
160         eth = eth_hdr(skb);
161 
162         if (unlikely(is_multicast_ether_addr(eth->h_dest))) {
163                 if (ether_addr_equal_64bits(eth->h_dest, dev->broadcast))
164                         skb->pkt_type = PACKET_BROADCAST;
165                 else
166                         skb->pkt_type = PACKET_MULTICAST;
167         }
168         else if (unlikely(!ether_addr_equal_64bits(eth->h_dest,
169                                                    dev->dev_addr)))
170                 skb->pkt_type = PACKET_OTHERHOST;
171 
172         /*
173          * Some variants of DSA tagging don't have an ethertype field
174          * at all, so we check here whether one of those tagging
175          * variants has been configured on the receiving interface,
176          * and if so, set skb->protocol without looking at the packet.
177          */
178         if (unlikely(netdev_uses_dsa(dev)))
179                 return htons(ETH_P_XDSA);
180 
181         if (likely(ntohs(eth->h_proto) >= ETH_P_802_3_MIN))
182                 return eth->h_proto;
183 
184         /*
185          *      This is a magic hack to spot IPX packets. Older Novell breaks
186          *      the protocol design and runs IPX over 802.3 without an 802.2 LLC
187          *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
188          *      won't work for fault tolerant netware but does for the rest.
189          */
190         sap = skb_header_pointer(skb, 0, sizeof(*sap), &_service_access_point);
191         if (sap && *sap == 0xFFFF)
192                 return htons(ETH_P_802_3);
193 
194         /*
195          *      Real 802.2 LLC
196          */
197         return htons(ETH_P_802_2);
198 }
199 EXPORT_SYMBOL(eth_type_trans);
200 
201 /**
202  * eth_header_parse - extract hardware address from packet
203  * @skb: packet to extract header from
204  * @haddr: destination buffer
205  */
206 int eth_header_parse(const struct sk_buff *skb, unsigned char *haddr)
207 {
208         const struct ethhdr *eth = eth_hdr(skb);
209         memcpy(haddr, eth->h_source, ETH_ALEN);
210         return ETH_ALEN;
211 }
212 EXPORT_SYMBOL(eth_header_parse);
213 
214 /**
215  * eth_header_cache - fill cache entry from neighbour
216  * @neigh: source neighbour
217  * @hh: destination cache entry
218  * @type: Ethernet type field
219  *
220  * Create an Ethernet header template from the neighbour.
221  */
222 int eth_header_cache(const struct neighbour *neigh, struct hh_cache *hh, __be16 type)
223 {
224         struct ethhdr *eth;
225         const struct net_device *dev = neigh->dev;
226 
227         eth = (struct ethhdr *)
228             (((u8 *) hh->hh_data) + (HH_DATA_OFF(sizeof(*eth))));
229 
230         if (type == htons(ETH_P_802_3))
231                 return -1;
232 
233         eth->h_proto = type;
234         memcpy(eth->h_source, dev->dev_addr, ETH_ALEN);
235         memcpy(eth->h_dest, neigh->ha, ETH_ALEN);
236         hh->hh_len = ETH_HLEN;
237         return 0;
238 }
239 EXPORT_SYMBOL(eth_header_cache);
240 
241 /**
242  * eth_header_cache_update - update cache entry
243  * @hh: destination cache entry
244  * @dev: network device
245  * @haddr: new hardware address
246  *
247  * Called by Address Resolution module to notify changes in address.
248  */
249 void eth_header_cache_update(struct hh_cache *hh,
250                              const struct net_device *dev,
251                              const unsigned char *haddr)
252 {
253         memcpy(((u8 *) hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)),
254                haddr, ETH_ALEN);
255 }
256 EXPORT_SYMBOL(eth_header_cache_update);
257 
258 /**
259  * eth_prepare_mac_addr_change - prepare for mac change
260  * @dev: network device
261  * @p: socket address
262  */
263 int eth_prepare_mac_addr_change(struct net_device *dev, void *p)
264 {
265         struct sockaddr *addr = p;
266 
267         if (!(dev->priv_flags & IFF_LIVE_ADDR_CHANGE) && netif_running(dev))
268                 return -EBUSY;
269         if (!is_valid_ether_addr(addr->sa_data))
270                 return -EADDRNOTAVAIL;
271         return 0;
272 }
273 EXPORT_SYMBOL(eth_prepare_mac_addr_change);
274 
275 /**
276  * eth_commit_mac_addr_change - commit mac change
277  * @dev: network device
278  * @p: socket address
279  */
280 void eth_commit_mac_addr_change(struct net_device *dev, void *p)
281 {
282         struct sockaddr *addr = p;
283 
284         memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
285 }
286 EXPORT_SYMBOL(eth_commit_mac_addr_change);
287 
288 /**
289  * eth_mac_addr - set new Ethernet hardware address
290  * @dev: network device
291  * @p: socket address
292  *
293  * Change hardware address of device.
294  *
295  * This doesn't change hardware matching, so needs to be overridden
296  * for most real devices.
297  */
298 int eth_mac_addr(struct net_device *dev, void *p)
299 {
300         int ret;
301 
302         ret = eth_prepare_mac_addr_change(dev, p);
303         if (ret < 0)
304                 return ret;
305         eth_commit_mac_addr_change(dev, p);
306         return 0;
307 }
308 EXPORT_SYMBOL(eth_mac_addr);
309 
310 /**
311  * eth_change_mtu - set new MTU size
312  * @dev: network device
313  * @new_mtu: new Maximum Transfer Unit
314  *
315  * Allow changing MTU size. Needs to be overridden for devices
316  * supporting jumbo frames.
317  */
318 int eth_change_mtu(struct net_device *dev, int new_mtu)
319 {
320         if (new_mtu < 68 || new_mtu > ETH_DATA_LEN)
321                 return -EINVAL;
322         dev->mtu = new_mtu;
323         return 0;
324 }
325 EXPORT_SYMBOL(eth_change_mtu);
326 
327 int eth_validate_addr(struct net_device *dev)
328 {
329         if (!is_valid_ether_addr(dev->dev_addr))
330                 return -EADDRNOTAVAIL;
331 
332         return 0;
333 }
334 EXPORT_SYMBOL(eth_validate_addr);
335 
336 const struct header_ops eth_header_ops ____cacheline_aligned = {
337         .create         = eth_header,
338         .parse          = eth_header_parse,
339         .cache          = eth_header_cache,
340         .cache_update   = eth_header_cache_update,
341 };
342 
343 /**
344  * ether_setup - setup Ethernet network device
345  * @dev: network device
346  *
347  * Fill in the fields of the device structure with Ethernet-generic values.
348  */
349 void ether_setup(struct net_device *dev)
350 {
351         dev->header_ops         = &eth_header_ops;
352         dev->type               = ARPHRD_ETHER;
353         dev->hard_header_len    = ETH_HLEN;
354         dev->mtu                = ETH_DATA_LEN;
355         dev->addr_len           = ETH_ALEN;
356         dev->tx_queue_len       = 1000; /* Ethernet wants good queues */
357         dev->flags              = IFF_BROADCAST|IFF_MULTICAST;
358         dev->priv_flags         |= IFF_TX_SKB_SHARING;
359 
360         eth_broadcast_addr(dev->broadcast);
361 
362 }
363 EXPORT_SYMBOL(ether_setup);
364 
365 /**
366  * alloc_etherdev_mqs - Allocates and sets up an Ethernet device
367  * @sizeof_priv: Size of additional driver-private structure to be allocated
368  *      for this Ethernet device
369  * @txqs: The number of TX queues this device has.
370  * @rxqs: The number of RX queues this device has.
371  *
372  * Fill in the fields of the device structure with Ethernet-generic
373  * values. Basically does everything except registering the device.
374  *
375  * Constructs a new net device, complete with a private data area of
376  * size (sizeof_priv).  A 32-byte (not bit) alignment is enforced for
377  * this private data area.
378  */
379 
380 struct net_device *alloc_etherdev_mqs(int sizeof_priv, unsigned int txqs,
381                                       unsigned int rxqs)
382 {
383         return alloc_netdev_mqs(sizeof_priv, "eth%d", NET_NAME_UNKNOWN,
384                                 ether_setup, txqs, rxqs);
385 }
386 EXPORT_SYMBOL(alloc_etherdev_mqs);
387 
388 ssize_t sysfs_format_mac(char *buf, const unsigned char *addr, int len)
389 {
390         return scnprintf(buf, PAGE_SIZE, "%*phC\n", len, addr);
391 }
392 EXPORT_SYMBOL(sysfs_format_mac);
393 
394 struct sk_buff **eth_gro_receive(struct sk_buff **head,
395                                  struct sk_buff *skb)
396 {
397         struct sk_buff *p, **pp = NULL;
398         struct ethhdr *eh, *eh2;
399         unsigned int hlen, off_eth;
400         const struct packet_offload *ptype;
401         __be16 type;
402         int flush = 1;
403 
404         off_eth = skb_gro_offset(skb);
405         hlen = off_eth + sizeof(*eh);
406         eh = skb_gro_header_fast(skb, off_eth);
407         if (skb_gro_header_hard(skb, hlen)) {
408                 eh = skb_gro_header_slow(skb, hlen, off_eth);
409                 if (unlikely(!eh))
410                         goto out;
411         }
412 
413         flush = 0;
414 
415         for (p = *head; p; p = p->next) {
416                 if (!NAPI_GRO_CB(p)->same_flow)
417                         continue;
418 
419                 eh2 = (struct ethhdr *)(p->data + off_eth);
420                 if (compare_ether_header(eh, eh2)) {
421                         NAPI_GRO_CB(p)->same_flow = 0;
422                         continue;
423                 }
424         }
425 
426         type = eh->h_proto;
427 
428         rcu_read_lock();
429         ptype = gro_find_receive_by_type(type);
430         if (ptype == NULL) {
431                 flush = 1;
432                 goto out_unlock;
433         }
434 
435         skb_gro_pull(skb, sizeof(*eh));
436         skb_gro_postpull_rcsum(skb, eh, sizeof(*eh));
437         pp = ptype->callbacks.gro_receive(head, skb);
438 
439 out_unlock:
440         rcu_read_unlock();
441 out:
442         NAPI_GRO_CB(skb)->flush |= flush;
443 
444         return pp;
445 }
446 EXPORT_SYMBOL(eth_gro_receive);
447 
448 int eth_gro_complete(struct sk_buff *skb, int nhoff)
449 {
450         struct ethhdr *eh = (struct ethhdr *)(skb->data + nhoff);
451         __be16 type = eh->h_proto;
452         struct packet_offload *ptype;
453         int err = -ENOSYS;
454 
455         if (skb->encapsulation)
456                 skb_set_inner_mac_header(skb, nhoff);
457 
458         rcu_read_lock();
459         ptype = gro_find_complete_by_type(type);
460         if (ptype != NULL)
461                 err = ptype->callbacks.gro_complete(skb, nhoff +
462                                                     sizeof(struct ethhdr));
463 
464         rcu_read_unlock();
465         return err;
466 }
467 EXPORT_SYMBOL(eth_gro_complete);
468 
469 static struct packet_offload eth_packet_offload __read_mostly = {
470         .type = cpu_to_be16(ETH_P_TEB),
471         .callbacks = {
472                 .gro_receive = eth_gro_receive,
473                 .gro_complete = eth_gro_complete,
474         },
475 };
476 
477 static int __init eth_offload_init(void)
478 {
479         dev_add_offload(&eth_packet_offload);
480 
481         return 0;
482 }
483 
484 fs_initcall(eth_offload_init);
485 

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