root/net/ethernet/eth.c

DEFINITIONS

1. eth_header
2. eth_get_headlen
3. eth_type_trans
4. eth_header_parse
5. eth_header_cache
6. eth_header_cache_update
7. eth_header_parse_protocol
8. eth_prepare_mac_addr_change
9. eth_commit_mac_addr_change
10. eth_mac_addr
11. eth_change_mtu
12. eth_validate_addr
13. ether_setup
14. alloc_etherdev_mqs
15. devm_free_netdev
16. devm_alloc_etherdev_mqs
17. sysfs_format_mac
18. eth_gro_receive
19. eth_gro_complete
20. eth_offload_init
21. arch_get_platform_mac_address
22. eth_platform_get_mac_address
23. nvmem_get_mac_address

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   4  *              operating system.  INET is implemented using the  BSD Socket
   5  *              interface as the means of communication with the user level.
   6  *
   7  *              Ethernet-type device handling.
   8  *
   9  * Version:     @(#)eth.c       1.0.7   05/25/93
  10  *
  11  * Authors:     Ross Biro
  12  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  13  *              Mark Evans, <evansmp@uhura.aston.ac.uk>
  14  *              Florian  La Roche, <rzsfl@rz.uni-sb.de>
  15  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  16  *
  17  * Fixes:
  18  *              Mr Linux        : Arp problems
  19  *              Alan Cox        : Generic queue tidyup (very tiny here)
  20  *              Alan Cox        : eth_header ntohs should be htons
  21  *              Alan Cox        : eth_rebuild_header missing an htons and
  22  *                                minor other things.
  23  *              Tegge           : Arp bug fixes.
  24  *              Florian         : Removed many unnecessary functions, code cleanup
  25  *                                and changes for new arp and skbuff.
  26  *              Alan Cox        : Redid header building to reflect new format.
  27  *              Alan Cox        : ARP only when compiled with CONFIG_INET
  28  *              Greg Page       : 802.2 and SNAP stuff.
  29  *              Alan Cox        : MAC layer pointers/new format.
  30  *              Paul Gortmaker  : eth_copy_and_sum shouldn't csum padding.
  31  *              Alan Cox        : Protect against forwarding explosions with
  32  *                                older network drivers and IFF_ALLMULTI.
  33  *      Christer Weinigel       : Better rebuild header message.
  34  *             Andrew Morton    : 26Feb01: kill ether_setup() - use netdev_boot_setup().
  35  */
  36 #include <linux/module.h>
  37 #include <linux/types.h>
  38 #include <linux/kernel.h>
  39 #include <linux/string.h>
  40 #include <linux/mm.h>
  41 #include <linux/socket.h>
  42 #include <linux/in.h>
  43 #include <linux/inet.h>
  44 #include <linux/ip.h>
  45 #include <linux/netdevice.h>
  46 #include <linux/nvmem-consumer.h>
  47 #include <linux/etherdevice.h>
  48 #include <linux/skbuff.h>
  49 #include <linux/errno.h>
  50 #include <linux/init.h>
  51 #include <linux/if_ether.h>
  52 #include <linux/of_net.h>
  53 #include <linux/pci.h>
  54 #include <net/dst.h>
  55 #include <net/arp.h>
  56 #include <net/sock.h>
  57 #include <net/ipv6.h>
  58 #include <net/ip.h>
  59 #include <net/dsa.h>
  60 #include <net/flow_dissector.h>
  61 #include <linux/uaccess.h>
  62 #include <net/pkt_sched.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 = 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  * @dev: pointer to network device
 119  * @data: pointer to start of frame
 120  * @len: total length of frame
 121  *
 122  * Make a best effort attempt to pull the length for all of the headers for
 123  * a given frame in a linear buffer.
 124  */
 125 u32 eth_get_headlen(const struct net_device *dev, void *data, unsigned int len)
 126 {
 127         const unsigned int flags = FLOW_DISSECTOR_F_PARSE_1ST_FRAG;
 128         const struct ethhdr *eth = (const struct ethhdr *)data;
 129         struct flow_keys_basic keys;
 130 
 131         /* this should never happen, but better safe than sorry */
 132         if (unlikely(len < sizeof(*eth)))
 133                 return len;
 134 
 135         /* parse any remaining L2/L3 headers, check for L4 */
 136         if (!skb_flow_dissect_flow_keys_basic(dev_net(dev), NULL, &keys, data,
 137                                               eth->h_proto, sizeof(*eth),
 138                                               len, flags))
 139                 return max_t(u32, keys.control.thoff, sizeof(*eth));
 140 
 141         /* parse for any L4 headers */
 142         return min_t(u32, __skb_get_poff(NULL, data, &keys, len), len);
 143 }
 144 EXPORT_SYMBOL(eth_get_headlen);
 145 
 146 /**
 147  * eth_type_trans - determine the packet's protocol ID.
 148  * @skb: received socket data
 149  * @dev: receiving network device
 150  *
 151  * The rule here is that we
 152  * assume 802.3 if the type field is short enough to be a length.
 153  * This is normal practice and works for any 'now in use' protocol.
 154  */
 155 __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
 156 {
 157         unsigned short _service_access_point;
 158         const unsigned short *sap;
 159         const struct ethhdr *eth;
 160 
 161         skb->dev = dev;
 162         skb_reset_mac_header(skb);
 163 
 164         eth = (struct ethhdr *)skb->data;
 165         skb_pull_inline(skb, ETH_HLEN);
 166 
 167         if (unlikely(!ether_addr_equal_64bits(eth->h_dest,
 168                                               dev->dev_addr))) {
 169                 if (unlikely(is_multicast_ether_addr_64bits(eth->h_dest))) {
 170                         if (ether_addr_equal_64bits(eth->h_dest, dev->broadcast))
 171                                 skb->pkt_type = PACKET_BROADCAST;
 172                         else
 173                                 skb->pkt_type = PACKET_MULTICAST;
 174                 } else {
 175                         skb->pkt_type = PACKET_OTHERHOST;
 176                 }
 177         }
 178 
 179         /*
 180          * Some variants of DSA tagging don't have an ethertype field
 181          * at all, so we check here whether one of those tagging
 182          * variants has been configured on the receiving interface,
 183          * and if so, set skb->protocol without looking at the packet.
 184          * The DSA tagging protocol may be able to decode some but not all
 185          * traffic (for example only for management). In that case give it the
 186          * option to filter the packets from which it can decode source port
 187          * information.
 188          */
 189         if (unlikely(netdev_uses_dsa(dev)) && dsa_can_decode(skb, dev))
 190                 return htons(ETH_P_XDSA);
 191 
 192         if (likely(eth_proto_is_802_3(eth->h_proto)))
 193                 return eth->h_proto;
 194 
 195         /*
 196          *      This is a magic hack to spot IPX packets. Older Novell breaks
 197          *      the protocol design and runs IPX over 802.3 without an 802.2 LLC
 198          *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
 199          *      won't work for fault tolerant netware but does for the rest.
 200          */
 201         sap = skb_header_pointer(skb, 0, sizeof(*sap), &_service_access_point);
 202         if (sap && *sap == 0xFFFF)
 203                 return htons(ETH_P_802_3);
 204 
 205         /*
 206          *      Real 802.2 LLC
 207          */
 208         return htons(ETH_P_802_2);
 209 }
 210 EXPORT_SYMBOL(eth_type_trans);
 211 
 212 /**
 213  * eth_header_parse - extract hardware address from packet
 214  * @skb: packet to extract header from
 215  * @haddr: destination buffer
 216  */
 217 int eth_header_parse(const struct sk_buff *skb, unsigned char *haddr)
 218 {
 219         const struct ethhdr *eth = eth_hdr(skb);
 220         memcpy(haddr, eth->h_source, ETH_ALEN);
 221         return ETH_ALEN;
 222 }
 223 EXPORT_SYMBOL(eth_header_parse);
 224 
 225 /**
 226  * eth_header_cache - fill cache entry from neighbour
 227  * @neigh: source neighbour
 228  * @hh: destination cache entry
 229  * @type: Ethernet type field
 230  *
 231  * Create an Ethernet header template from the neighbour.
 232  */
 233 int eth_header_cache(const struct neighbour *neigh, struct hh_cache *hh, __be16 type)
 234 {
 235         struct ethhdr *eth;
 236         const struct net_device *dev = neigh->dev;
 237 
 238         eth = (struct ethhdr *)
 239             (((u8 *) hh->hh_data) + (HH_DATA_OFF(sizeof(*eth))));
 240 
 241         if (type == htons(ETH_P_802_3))
 242                 return -1;
 243 
 244         eth->h_proto = type;
 245         memcpy(eth->h_source, dev->dev_addr, ETH_ALEN);
 246         memcpy(eth->h_dest, neigh->ha, ETH_ALEN);
 247 
 248         /* Pairs with READ_ONCE() in neigh_resolve_output(),
 249          * neigh_hh_output() and neigh_update_hhs().
 250          */
 251         smp_store_release(&hh->hh_len, ETH_HLEN);
 252 
 253         return 0;
 254 }
 255 EXPORT_SYMBOL(eth_header_cache);
 256 
 257 /**
 258  * eth_header_cache_update - update cache entry
 259  * @hh: destination cache entry
 260  * @dev: network device
 261  * @haddr: new hardware address
 262  *
 263  * Called by Address Resolution module to notify changes in address.
 264  */
 265 void eth_header_cache_update(struct hh_cache *hh,
 266                              const struct net_device *dev,
 267                              const unsigned char *haddr)
 268 {
 269         memcpy(((u8 *) hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)),
 270                haddr, ETH_ALEN);
 271 }
 272 EXPORT_SYMBOL(eth_header_cache_update);
 273 
 274 /**
 275  * eth_header_parser_protocol - extract protocol from L2 header
 276  * @skb: packet to extract protocol from
 277  */
 278 __be16 eth_header_parse_protocol(const struct sk_buff *skb)
 279 {
 280         const struct ethhdr *eth = eth_hdr(skb);
 281 
 282         return eth->h_proto;
 283 }
 284 EXPORT_SYMBOL(eth_header_parse_protocol);
 285 
 286 /**
 287  * eth_prepare_mac_addr_change - prepare for mac change
 288  * @dev: network device
 289  * @p: socket address
 290  */
 291 int eth_prepare_mac_addr_change(struct net_device *dev, void *p)
 292 {
 293         struct sockaddr *addr = p;
 294 
 295         if (!(dev->priv_flags & IFF_LIVE_ADDR_CHANGE) && netif_running(dev))
 296                 return -EBUSY;
 297         if (!is_valid_ether_addr(addr->sa_data))
 298                 return -EADDRNOTAVAIL;
 299         return 0;
 300 }
 301 EXPORT_SYMBOL(eth_prepare_mac_addr_change);
 302 
 303 /**
 304  * eth_commit_mac_addr_change - commit mac change
 305  * @dev: network device
 306  * @p: socket address
 307  */
 308 void eth_commit_mac_addr_change(struct net_device *dev, void *p)
 309 {
 310         struct sockaddr *addr = p;
 311 
 312         memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
 313 }
 314 EXPORT_SYMBOL(eth_commit_mac_addr_change);
 315 
 316 /**
 317  * eth_mac_addr - set new Ethernet hardware address
 318  * @dev: network device
 319  * @p: socket address
 320  *
 321  * Change hardware address of device.
 322  *
 323  * This doesn't change hardware matching, so needs to be overridden
 324  * for most real devices.
 325  */
 326 int eth_mac_addr(struct net_device *dev, void *p)
 327 {
 328         int ret;
 329 
 330         ret = eth_prepare_mac_addr_change(dev, p);
 331         if (ret < 0)
 332                 return ret;
 333         eth_commit_mac_addr_change(dev, p);
 334         return 0;
 335 }
 336 EXPORT_SYMBOL(eth_mac_addr);
 337 
 338 /**
 339  * eth_change_mtu - set new MTU size
 340  * @dev: network device
 341  * @new_mtu: new Maximum Transfer Unit
 342  *
 343  * Allow changing MTU size. Needs to be overridden for devices
 344  * supporting jumbo frames.
 345  */
 346 int eth_change_mtu(struct net_device *dev, int new_mtu)
 347 {
 348         netdev_warn(dev, "%s is deprecated\n", __func__);
 349         dev->mtu = new_mtu;
 350         return 0;
 351 }
 352 EXPORT_SYMBOL(eth_change_mtu);
 353 
 354 int eth_validate_addr(struct net_device *dev)
 355 {
 356         if (!is_valid_ether_addr(dev->dev_addr))
 357                 return -EADDRNOTAVAIL;
 358 
 359         return 0;
 360 }
 361 EXPORT_SYMBOL(eth_validate_addr);
 362 
 363 const struct header_ops eth_header_ops ____cacheline_aligned = {
 364         .create         = eth_header,
 365         .parse          = eth_header_parse,
 366         .cache          = eth_header_cache,
 367         .cache_update   = eth_header_cache_update,
 368         .parse_protocol = eth_header_parse_protocol,
 369 };
 370 
 371 /**
 372  * ether_setup - setup Ethernet network device
 373  * @dev: network device
 374  *
 375  * Fill in the fields of the device structure with Ethernet-generic values.
 376  */
 377 void ether_setup(struct net_device *dev)
 378 {
 379         dev->header_ops         = &eth_header_ops;
 380         dev->type               = ARPHRD_ETHER;
 381         dev->hard_header_len    = ETH_HLEN;
 382         dev->min_header_len     = ETH_HLEN;
 383         dev->mtu                = ETH_DATA_LEN;
 384         dev->min_mtu            = ETH_MIN_MTU;
 385         dev->max_mtu            = ETH_DATA_LEN;
 386         dev->addr_len           = ETH_ALEN;
 387         dev->tx_queue_len       = DEFAULT_TX_QUEUE_LEN;
 388         dev->flags              = IFF_BROADCAST|IFF_MULTICAST;
 389         dev->priv_flags         |= IFF_TX_SKB_SHARING;
 390 
 391         eth_broadcast_addr(dev->broadcast);
 392 
 393 }
 394 EXPORT_SYMBOL(ether_setup);
 395 
 396 /**
 397  * alloc_etherdev_mqs - Allocates and sets up an Ethernet device
 398  * @sizeof_priv: Size of additional driver-private structure to be allocated
 399  *      for this Ethernet device
 400  * @txqs: The number of TX queues this device has.
 401  * @rxqs: The number of RX queues this device has.
 402  *
 403  * Fill in the fields of the device structure with Ethernet-generic
 404  * values. Basically does everything except registering the device.
 405  *
 406  * Constructs a new net device, complete with a private data area of
 407  * size (sizeof_priv).  A 32-byte (not bit) alignment is enforced for
 408  * this private data area.
 409  */
 410 
 411 struct net_device *alloc_etherdev_mqs(int sizeof_priv, unsigned int txqs,
 412                                       unsigned int rxqs)
 413 {
 414         return alloc_netdev_mqs(sizeof_priv, "eth%d", NET_NAME_UNKNOWN,
 415                                 ether_setup, txqs, rxqs);
 416 }
 417 EXPORT_SYMBOL(alloc_etherdev_mqs);
 418 
 419 static void devm_free_netdev(struct device *dev, void *res)
 420 {
 421         free_netdev(*(struct net_device **)res);
 422 }
 423 
 424 struct net_device *devm_alloc_etherdev_mqs(struct device *dev, int sizeof_priv,
 425                                            unsigned int txqs, unsigned int rxqs)
 426 {
 427         struct net_device **dr;
 428         struct net_device *netdev;
 429 
 430         dr = devres_alloc(devm_free_netdev, sizeof(*dr), GFP_KERNEL);
 431         if (!dr)
 432                 return NULL;
 433 
 434         netdev = alloc_etherdev_mqs(sizeof_priv, txqs, rxqs);
 435         if (!netdev) {
 436                 devres_free(dr);
 437                 return NULL;
 438         }
 439 
 440         *dr = netdev;
 441         devres_add(dev, dr);
 442 
 443         return netdev;
 444 }
 445 EXPORT_SYMBOL(devm_alloc_etherdev_mqs);
 446 
 447 ssize_t sysfs_format_mac(char *buf, const unsigned char *addr, int len)
 448 {
 449         return scnprintf(buf, PAGE_SIZE, "%*phC\n", len, addr);
 450 }
 451 EXPORT_SYMBOL(sysfs_format_mac);
 452 
 453 struct sk_buff *eth_gro_receive(struct list_head *head, struct sk_buff *skb)
 454 {
 455         const struct packet_offload *ptype;
 456         unsigned int hlen, off_eth;
 457         struct sk_buff *pp = NULL;
 458         struct ethhdr *eh, *eh2;
 459         struct sk_buff *p;
 460         __be16 type;
 461         int flush = 1;
 462 
 463         off_eth = skb_gro_offset(skb);
 464         hlen = off_eth + sizeof(*eh);
 465         eh = skb_gro_header_fast(skb, off_eth);
 466         if (skb_gro_header_hard(skb, hlen)) {
 467                 eh = skb_gro_header_slow(skb, hlen, off_eth);
 468                 if (unlikely(!eh))
 469                         goto out;
 470         }
 471 
 472         flush = 0;
 473 
 474         list_for_each_entry(p, head, list) {
 475                 if (!NAPI_GRO_CB(p)->same_flow)
 476                         continue;
 477 
 478                 eh2 = (struct ethhdr *)(p->data + off_eth);
 479                 if (compare_ether_header(eh, eh2)) {
 480                         NAPI_GRO_CB(p)->same_flow = 0;
 481                         continue;
 482                 }
 483         }
 484 
 485         type = eh->h_proto;
 486 
 487         rcu_read_lock();
 488         ptype = gro_find_receive_by_type(type);
 489         if (ptype == NULL) {
 490                 flush = 1;
 491                 goto out_unlock;
 492         }
 493 
 494         skb_gro_pull(skb, sizeof(*eh));
 495         skb_gro_postpull_rcsum(skb, eh, sizeof(*eh));
 496         pp = call_gro_receive(ptype->callbacks.gro_receive, head, skb);
 497 
 498 out_unlock:
 499         rcu_read_unlock();
 500 out:
 501         skb_gro_flush_final(skb, pp, flush);
 502 
 503         return pp;
 504 }
 505 EXPORT_SYMBOL(eth_gro_receive);
 506 
 507 int eth_gro_complete(struct sk_buff *skb, int nhoff)
 508 {
 509         struct ethhdr *eh = (struct ethhdr *)(skb->data + nhoff);
 510         __be16 type = eh->h_proto;
 511         struct packet_offload *ptype;
 512         int err = -ENOSYS;
 513 
 514         if (skb->encapsulation)
 515                 skb_set_inner_mac_header(skb, nhoff);
 516 
 517         rcu_read_lock();
 518         ptype = gro_find_complete_by_type(type);
 519         if (ptype != NULL)
 520                 err = ptype->callbacks.gro_complete(skb, nhoff +
 521                                                     sizeof(struct ethhdr));
 522 
 523         rcu_read_unlock();
 524         return err;
 525 }
 526 EXPORT_SYMBOL(eth_gro_complete);
 527 
 528 static struct packet_offload eth_packet_offload __read_mostly = {
 529         .type = cpu_to_be16(ETH_P_TEB),
 530         .priority = 10,
 531         .callbacks = {
 532                 .gro_receive = eth_gro_receive,
 533                 .gro_complete = eth_gro_complete,
 534         },
 535 };
 536 
 537 static int __init eth_offload_init(void)
 538 {
 539         dev_add_offload(&eth_packet_offload);
 540 
 541         return 0;
 542 }
 543 
 544 fs_initcall(eth_offload_init);
 545 
 546 unsigned char * __weak arch_get_platform_mac_address(void)
 547 {
 548         return NULL;
 549 }
 550 
 551 int eth_platform_get_mac_address(struct device *dev, u8 *mac_addr)
 552 {
 553         const unsigned char *addr = NULL;
 554 
 555         if (dev->of_node)
 556                 addr = of_get_mac_address(dev->of_node);
 557         if (IS_ERR_OR_NULL(addr))
 558                 addr = arch_get_platform_mac_address();
 559 
 560         if (!addr)
 561                 return -ENODEV;
 562 
 563         ether_addr_copy(mac_addr, addr);
 564 
 565         return 0;
 566 }
 567 EXPORT_SYMBOL(eth_platform_get_mac_address);
 568 
 569 /**
 570  * Obtain the MAC address from an nvmem cell named 'mac-address' associated
 571  * with given device.
 572  *
 573  * @dev:        Device with which the mac-address cell is associated.
 574  * @addrbuf:    Buffer to which the MAC address will be copied on success.
 575  *
 576  * Returns 0 on success or a negative error number on failure.
 577  */
 578 int nvmem_get_mac_address(struct device *dev, void *addrbuf)
 579 {
 580         struct nvmem_cell *cell;
 581         const void *mac;
 582         size_t len;
 583 
 584         cell = nvmem_cell_get(dev, "mac-address");
 585         if (IS_ERR(cell))
 586                 return PTR_ERR(cell);
 587 
 588         mac = nvmem_cell_read(cell, &len);
 589         nvmem_cell_put(cell);
 590 
 591         if (IS_ERR(mac))
 592                 return PTR_ERR(mac);
 593 
 594         if (len != ETH_ALEN || !is_valid_ether_addr(mac)) {
 595                 kfree(mac);
 596                 return -EINVAL;
 597         }
 598 
 599         ether_addr_copy(addrbuf, mac);
 600         kfree(mac);
 601 
 602         return 0;
 603 }
 604 EXPORT_SYMBOL(nvmem_get_mac_address);