root/include/linux/if_vlan.h

INCLUDED FROM

DEFINITIONS

1. vlan_eth_hdr
2. is_vlan_dev
3. vlan_get_rx_ctag_filter_info
4. vlan_drop_rx_ctag_filter_info
5. vlan_get_rx_stag_filter_info
6. vlan_drop_rx_stag_filter_info
7. vlan_dev_get_egress_qos_mask
8. __vlan_find_dev_deep_rcu
9. vlan_for_each
10. vlan_dev_real_dev
11. vlan_dev_vlan_id
12. vlan_dev_vlan_proto
13. vlan_dev_get_egress_qos_mask
14. vlan_do_receive
15. vlan_vid_add
16. vlan_vid_del
17. vlan_vids_add_by_dev
18. vlan_vids_del_by_dev
19. vlan_uses_dev
20. eth_type_vlan
21. vlan_hw_offload_capable
22. __vlan_insert_inner_tag
23. __vlan_insert_tag
24. vlan_insert_inner_tag
25. vlan_insert_tag
26. vlan_insert_tag_set_proto
27. __vlan_hwaccel_clear_tag
28. __vlan_hwaccel_copy_tag
29. __vlan_hwaccel_push_inside
30. __vlan_hwaccel_put_tag
31. __vlan_get_tag
32. __vlan_hwaccel_get_tag
33. vlan_get_tag
34. __vlan_get_protocol
35. vlan_get_protocol
36. vlan_set_encap_proto
37. skb_vlan_tagged
38. skb_vlan_tagged_multi
39. vlan_features_check
40. compare_vlan_header

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  * VLAN         An implementation of 802.1Q VLAN tagging.
   4  *
   5  * Authors:     Ben Greear <greearb@candelatech.com>
   6  */
   7 #ifndef _LINUX_IF_VLAN_H_
   8 #define _LINUX_IF_VLAN_H_
   9 
  10 #include <linux/netdevice.h>
  11 #include <linux/etherdevice.h>
  12 #include <linux/rtnetlink.h>
  13 #include <linux/bug.h>
  14 #include <uapi/linux/if_vlan.h>
  15 
  16 #define VLAN_HLEN       4               /* The additional bytes required by VLAN
  17                                          * (in addition to the Ethernet header)
  18                                          */
  19 #define VLAN_ETH_HLEN   18              /* Total octets in header.       */
  20 #define VLAN_ETH_ZLEN   64              /* Min. octets in frame sans FCS */
  21 
  22 /*
  23  * According to 802.3ac, the packet can be 4 bytes longer. --Klika Jan
  24  */
  25 #define VLAN_ETH_DATA_LEN       1500    /* Max. octets in payload        */
  26 #define VLAN_ETH_FRAME_LEN      1518    /* Max. octets in frame sans FCS */
  27 
  28 /*
  29  *      struct vlan_hdr - vlan header
  30  *      @h_vlan_TCI: priority and VLAN ID
  31  *      @h_vlan_encapsulated_proto: packet type ID or len
  32  */
  33 struct vlan_hdr {
  34         __be16  h_vlan_TCI;
  35         __be16  h_vlan_encapsulated_proto;
  36 };
  37 
  38 /**
  39  *      struct vlan_ethhdr - vlan ethernet header (ethhdr + vlan_hdr)
  40  *      @h_dest: destination ethernet address
  41  *      @h_source: source ethernet address
  42  *      @h_vlan_proto: ethernet protocol
  43  *      @h_vlan_TCI: priority and VLAN ID
  44  *      @h_vlan_encapsulated_proto: packet type ID or len
  45  */
  46 struct vlan_ethhdr {
  47         unsigned char   h_dest[ETH_ALEN];
  48         unsigned char   h_source[ETH_ALEN];
  49         __be16          h_vlan_proto;
  50         __be16          h_vlan_TCI;
  51         __be16          h_vlan_encapsulated_proto;
  52 };
  53 
  54 #include <linux/skbuff.h>
  55 
  56 static inline struct vlan_ethhdr *vlan_eth_hdr(const struct sk_buff *skb)
  57 {
  58         return (struct vlan_ethhdr *)skb_mac_header(skb);
  59 }
  60 
  61 #define VLAN_PRIO_MASK          0xe000 /* Priority Code Point */
  62 #define VLAN_PRIO_SHIFT         13
  63 #define VLAN_CFI_MASK           0x1000 /* Canonical Format Indicator / Drop Eligible Indicator */
  64 #define VLAN_VID_MASK           0x0fff /* VLAN Identifier */
  65 #define VLAN_N_VID              4096
  66 
  67 /* found in socket.c */
  68 extern void vlan_ioctl_set(int (*hook)(struct net *, void __user *));
  69 
  70 static inline bool is_vlan_dev(const struct net_device *dev)
  71 {
  72         return dev->priv_flags & IFF_802_1Q_VLAN;
  73 }
  74 
  75 #define skb_vlan_tag_present(__skb)     ((__skb)->vlan_present)
  76 #define skb_vlan_tag_get(__skb)         ((__skb)->vlan_tci)
  77 #define skb_vlan_tag_get_id(__skb)      ((__skb)->vlan_tci & VLAN_VID_MASK)
  78 #define skb_vlan_tag_get_cfi(__skb)     (!!((__skb)->vlan_tci & VLAN_CFI_MASK))
  79 #define skb_vlan_tag_get_prio(__skb)    (((__skb)->vlan_tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT)
  80 
  81 static inline int vlan_get_rx_ctag_filter_info(struct net_device *dev)
  82 {
  83         ASSERT_RTNL();
  84         return notifier_to_errno(call_netdevice_notifiers(NETDEV_CVLAN_FILTER_PUSH_INFO, dev));
  85 }
  86 
  87 static inline void vlan_drop_rx_ctag_filter_info(struct net_device *dev)
  88 {
  89         ASSERT_RTNL();
  90         call_netdevice_notifiers(NETDEV_CVLAN_FILTER_DROP_INFO, dev);
  91 }
  92 
  93 static inline int vlan_get_rx_stag_filter_info(struct net_device *dev)
  94 {
  95         ASSERT_RTNL();
  96         return notifier_to_errno(call_netdevice_notifiers(NETDEV_SVLAN_FILTER_PUSH_INFO, dev));
  97 }
  98 
  99 static inline void vlan_drop_rx_stag_filter_info(struct net_device *dev)
 100 {
 101         ASSERT_RTNL();
 102         call_netdevice_notifiers(NETDEV_SVLAN_FILTER_DROP_INFO, dev);
 103 }
 104 
 105 /**
 106  *      struct vlan_pcpu_stats - VLAN percpu rx/tx stats
 107  *      @rx_packets: number of received packets
 108  *      @rx_bytes: number of received bytes
 109  *      @rx_multicast: number of received multicast packets
 110  *      @tx_packets: number of transmitted packets
 111  *      @tx_bytes: number of transmitted bytes
 112  *      @syncp: synchronization point for 64bit counters
 113  *      @rx_errors: number of rx errors
 114  *      @tx_dropped: number of tx drops
 115  */
 116 struct vlan_pcpu_stats {
 117         u64                     rx_packets;
 118         u64                     rx_bytes;
 119         u64                     rx_multicast;
 120         u64                     tx_packets;
 121         u64                     tx_bytes;
 122         struct u64_stats_sync   syncp;
 123         u32                     rx_errors;
 124         u32                     tx_dropped;
 125 };
 126 
 127 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 128 
 129 extern struct net_device *__vlan_find_dev_deep_rcu(struct net_device *real_dev,
 130                                                __be16 vlan_proto, u16 vlan_id);
 131 extern int vlan_for_each(struct net_device *dev,
 132                          int (*action)(struct net_device *dev, int vid,
 133                                        void *arg), void *arg);
 134 extern struct net_device *vlan_dev_real_dev(const struct net_device *dev);
 135 extern u16 vlan_dev_vlan_id(const struct net_device *dev);
 136 extern __be16 vlan_dev_vlan_proto(const struct net_device *dev);
 137 
 138 /**
 139  *      struct vlan_priority_tci_mapping - vlan egress priority mappings
 140  *      @priority: skb priority
 141  *      @vlan_qos: vlan priority: (skb->priority << 13) & 0xE000
 142  *      @next: pointer to next struct
 143  */
 144 struct vlan_priority_tci_mapping {
 145         u32                                     priority;
 146         u16                                     vlan_qos;
 147         struct vlan_priority_tci_mapping        *next;
 148 };
 149 
 150 struct proc_dir_entry;
 151 struct netpoll;
 152 
 153 /**
 154  *      struct vlan_dev_priv - VLAN private device data
 155  *      @nr_ingress_mappings: number of ingress priority mappings
 156  *      @ingress_priority_map: ingress priority mappings
 157  *      @nr_egress_mappings: number of egress priority mappings
 158  *      @egress_priority_map: hash of egress priority mappings
 159  *      @vlan_proto: VLAN encapsulation protocol
 160  *      @vlan_id: VLAN identifier
 161  *      @flags: device flags
 162  *      @real_dev: underlying netdevice
 163  *      @real_dev_addr: address of underlying netdevice
 164  *      @dent: proc dir entry
 165  *      @vlan_pcpu_stats: ptr to percpu rx stats
 166  */
 167 struct vlan_dev_priv {
 168         unsigned int                            nr_ingress_mappings;
 169         u32                                     ingress_priority_map[8];
 170         unsigned int                            nr_egress_mappings;
 171         struct vlan_priority_tci_mapping        *egress_priority_map[16];
 172 
 173         __be16                                  vlan_proto;
 174         u16                                     vlan_id;
 175         u16                                     flags;
 176 
 177         struct net_device                       *real_dev;
 178         unsigned char                           real_dev_addr[ETH_ALEN];
 179 
 180         struct proc_dir_entry                   *dent;
 181         struct vlan_pcpu_stats __percpu         *vlan_pcpu_stats;
 182 #ifdef CONFIG_NET_POLL_CONTROLLER
 183         struct netpoll                          *netpoll;
 184 #endif
 185 };
 186 
 187 static inline struct vlan_dev_priv *vlan_dev_priv(const struct net_device *dev)
 188 {
 189         return netdev_priv(dev);
 190 }
 191 
 192 static inline u16
 193 vlan_dev_get_egress_qos_mask(struct net_device *dev, u32 skprio)
 194 {
 195         struct vlan_priority_tci_mapping *mp;
 196 
 197         smp_rmb(); /* coupled with smp_wmb() in vlan_dev_set_egress_priority() */
 198 
 199         mp = vlan_dev_priv(dev)->egress_priority_map[(skprio & 0xF)];
 200         while (mp) {
 201                 if (mp->priority == skprio) {
 202                         return mp->vlan_qos; /* This should already be shifted
 203                                               * to mask correctly with the
 204                                               * VLAN's TCI */
 205                 }
 206                 mp = mp->next;
 207         }
 208         return 0;
 209 }
 210 
 211 extern bool vlan_do_receive(struct sk_buff **skb);
 212 
 213 extern int vlan_vid_add(struct net_device *dev, __be16 proto, u16 vid);
 214 extern void vlan_vid_del(struct net_device *dev, __be16 proto, u16 vid);
 215 
 216 extern int vlan_vids_add_by_dev(struct net_device *dev,
 217                                 const struct net_device *by_dev);
 218 extern void vlan_vids_del_by_dev(struct net_device *dev,
 219                                  const struct net_device *by_dev);
 220 
 221 extern bool vlan_uses_dev(const struct net_device *dev);
 222 
 223 #else
 224 static inline struct net_device *
 225 __vlan_find_dev_deep_rcu(struct net_device *real_dev,
 226                      __be16 vlan_proto, u16 vlan_id)
 227 {
 228         return NULL;
 229 }
 230 
 231 static inline int
 232 vlan_for_each(struct net_device *dev,
 233               int (*action)(struct net_device *dev, int vid, void *arg),
 234               void *arg)
 235 {
 236         return 0;
 237 }
 238 
 239 static inline struct net_device *vlan_dev_real_dev(const struct net_device *dev)
 240 {
 241         BUG();
 242         return NULL;
 243 }
 244 
 245 static inline u16 vlan_dev_vlan_id(const struct net_device *dev)
 246 {
 247         BUG();
 248         return 0;
 249 }
 250 
 251 static inline __be16 vlan_dev_vlan_proto(const struct net_device *dev)
 252 {
 253         BUG();
 254         return 0;
 255 }
 256 
 257 static inline u16 vlan_dev_get_egress_qos_mask(struct net_device *dev,
 258                                                u32 skprio)
 259 {
 260         return 0;
 261 }
 262 
 263 static inline bool vlan_do_receive(struct sk_buff **skb)
 264 {
 265         return false;
 266 }
 267 
 268 static inline int vlan_vid_add(struct net_device *dev, __be16 proto, u16 vid)
 269 {
 270         return 0;
 271 }
 272 
 273 static inline void vlan_vid_del(struct net_device *dev, __be16 proto, u16 vid)
 274 {
 275 }
 276 
 277 static inline int vlan_vids_add_by_dev(struct net_device *dev,
 278                                        const struct net_device *by_dev)
 279 {
 280         return 0;
 281 }
 282 
 283 static inline void vlan_vids_del_by_dev(struct net_device *dev,
 284                                         const struct net_device *by_dev)
 285 {
 286 }
 287 
 288 static inline bool vlan_uses_dev(const struct net_device *dev)
 289 {
 290         return false;
 291 }
 292 #endif
 293 
 294 /**
 295  * eth_type_vlan - check for valid vlan ether type.
 296  * @ethertype: ether type to check
 297  *
 298  * Returns true if the ether type is a vlan ether type.
 299  */
 300 static inline bool eth_type_vlan(__be16 ethertype)
 301 {
 302         switch (ethertype) {
 303         case htons(ETH_P_8021Q):
 304         case htons(ETH_P_8021AD):
 305                 return true;
 306         default:
 307                 return false;
 308         }
 309 }
 310 
 311 static inline bool vlan_hw_offload_capable(netdev_features_t features,
 312                                            __be16 proto)
 313 {
 314         if (proto == htons(ETH_P_8021Q) && features & NETIF_F_HW_VLAN_CTAG_TX)
 315                 return true;
 316         if (proto == htons(ETH_P_8021AD) && features & NETIF_F_HW_VLAN_STAG_TX)
 317                 return true;
 318         return false;
 319 }
 320 
 321 /**
 322  * __vlan_insert_inner_tag - inner VLAN tag inserting
 323  * @skb: skbuff to tag
 324  * @vlan_proto: VLAN encapsulation protocol
 325  * @vlan_tci: VLAN TCI to insert
 326  * @mac_len: MAC header length including outer vlan headers
 327  *
 328  * Inserts the VLAN tag into @skb as part of the payload at offset mac_len
 329  * Returns error if skb_cow_head fails.
 330  *
 331  * Does not change skb->protocol so this function can be used during receive.
 332  */
 333 static inline int __vlan_insert_inner_tag(struct sk_buff *skb,
 334                                           __be16 vlan_proto, u16 vlan_tci,
 335                                           unsigned int mac_len)
 336 {
 337         struct vlan_ethhdr *veth;
 338 
 339         if (skb_cow_head(skb, VLAN_HLEN) < 0)
 340                 return -ENOMEM;
 341 
 342         skb_push(skb, VLAN_HLEN);
 343 
 344         /* Move the mac header sans proto to the beginning of the new header. */
 345         if (likely(mac_len > ETH_TLEN))
 346                 memmove(skb->data, skb->data + VLAN_HLEN, mac_len - ETH_TLEN);
 347         skb->mac_header -= VLAN_HLEN;
 348 
 349         veth = (struct vlan_ethhdr *)(skb->data + mac_len - ETH_HLEN);
 350 
 351         /* first, the ethernet type */
 352         if (likely(mac_len >= ETH_TLEN)) {
 353                 /* h_vlan_encapsulated_proto should already be populated, and
 354                  * skb->data has space for h_vlan_proto
 355                  */
 356                 veth->h_vlan_proto = vlan_proto;
 357         } else {
 358                 /* h_vlan_encapsulated_proto should not be populated, and
 359                  * skb->data has no space for h_vlan_proto
 360                  */
 361                 veth->h_vlan_encapsulated_proto = skb->protocol;
 362         }
 363 
 364         /* now, the TCI */
 365         veth->h_vlan_TCI = htons(vlan_tci);
 366 
 367         return 0;
 368 }
 369 
 370 /**
 371  * __vlan_insert_tag - regular VLAN tag inserting
 372  * @skb: skbuff to tag
 373  * @vlan_proto: VLAN encapsulation protocol
 374  * @vlan_tci: VLAN TCI to insert
 375  *
 376  * Inserts the VLAN tag into @skb as part of the payload
 377  * Returns error if skb_cow_head fails.
 378  *
 379  * Does not change skb->protocol so this function can be used during receive.
 380  */
 381 static inline int __vlan_insert_tag(struct sk_buff *skb,
 382                                     __be16 vlan_proto, u16 vlan_tci)
 383 {
 384         return __vlan_insert_inner_tag(skb, vlan_proto, vlan_tci, ETH_HLEN);
 385 }
 386 
 387 /**
 388  * vlan_insert_inner_tag - inner VLAN tag inserting
 389  * @skb: skbuff to tag
 390  * @vlan_proto: VLAN encapsulation protocol
 391  * @vlan_tci: VLAN TCI to insert
 392  * @mac_len: MAC header length including outer vlan headers
 393  *
 394  * Inserts the VLAN tag into @skb as part of the payload at offset mac_len
 395  * Returns a VLAN tagged skb. If a new skb is created, @skb is freed.
 396  *
 397  * Following the skb_unshare() example, in case of error, the calling function
 398  * doesn't have to worry about freeing the original skb.
 399  *
 400  * Does not change skb->protocol so this function can be used during receive.
 401  */
 402 static inline struct sk_buff *vlan_insert_inner_tag(struct sk_buff *skb,
 403                                                     __be16 vlan_proto,
 404                                                     u16 vlan_tci,
 405                                                     unsigned int mac_len)
 406 {
 407         int err;
 408 
 409         err = __vlan_insert_inner_tag(skb, vlan_proto, vlan_tci, mac_len);
 410         if (err) {
 411                 dev_kfree_skb_any(skb);
 412                 return NULL;
 413         }
 414         return skb;
 415 }
 416 
 417 /**
 418  * vlan_insert_tag - regular VLAN tag inserting
 419  * @skb: skbuff to tag
 420  * @vlan_proto: VLAN encapsulation protocol
 421  * @vlan_tci: VLAN TCI to insert
 422  *
 423  * Inserts the VLAN tag into @skb as part of the payload
 424  * Returns a VLAN tagged skb. If a new skb is created, @skb is freed.
 425  *
 426  * Following the skb_unshare() example, in case of error, the calling function
 427  * doesn't have to worry about freeing the original skb.
 428  *
 429  * Does not change skb->protocol so this function can be used during receive.
 430  */
 431 static inline struct sk_buff *vlan_insert_tag(struct sk_buff *skb,
 432                                               __be16 vlan_proto, u16 vlan_tci)
 433 {
 434         return vlan_insert_inner_tag(skb, vlan_proto, vlan_tci, ETH_HLEN);
 435 }
 436 
 437 /**
 438  * vlan_insert_tag_set_proto - regular VLAN tag inserting
 439  * @skb: skbuff to tag
 440  * @vlan_proto: VLAN encapsulation protocol
 441  * @vlan_tci: VLAN TCI to insert
 442  *
 443  * Inserts the VLAN tag into @skb as part of the payload
 444  * Returns a VLAN tagged skb. If a new skb is created, @skb is freed.
 445  *
 446  * Following the skb_unshare() example, in case of error, the calling function
 447  * doesn't have to worry about freeing the original skb.
 448  */
 449 static inline struct sk_buff *vlan_insert_tag_set_proto(struct sk_buff *skb,
 450                                                         __be16 vlan_proto,
 451                                                         u16 vlan_tci)
 452 {
 453         skb = vlan_insert_tag(skb, vlan_proto, vlan_tci);
 454         if (skb)
 455                 skb->protocol = vlan_proto;
 456         return skb;
 457 }
 458 
 459 /**
 460  * __vlan_hwaccel_clear_tag - clear hardware accelerated VLAN info
 461  * @skb: skbuff to clear
 462  *
 463  * Clears the VLAN information from @skb
 464  */
 465 static inline void __vlan_hwaccel_clear_tag(struct sk_buff *skb)
 466 {
 467         skb->vlan_present = 0;
 468 }
 469 
 470 /**
 471  * __vlan_hwaccel_copy_tag - copy hardware accelerated VLAN info from another skb
 472  * @dst: skbuff to copy to
 473  * @src: skbuff to copy from
 474  *
 475  * Copies VLAN information from @src to @dst (for branchless code)
 476  */
 477 static inline void __vlan_hwaccel_copy_tag(struct sk_buff *dst, const struct sk_buff *src)
 478 {
 479         dst->vlan_present = src->vlan_present;
 480         dst->vlan_proto = src->vlan_proto;
 481         dst->vlan_tci = src->vlan_tci;
 482 }
 483 
 484 /*
 485  * __vlan_hwaccel_push_inside - pushes vlan tag to the payload
 486  * @skb: skbuff to tag
 487  *
 488  * Pushes the VLAN tag from @skb->vlan_tci inside to the payload.
 489  *
 490  * Following the skb_unshare() example, in case of error, the calling function
 491  * doesn't have to worry about freeing the original skb.
 492  */
 493 static inline struct sk_buff *__vlan_hwaccel_push_inside(struct sk_buff *skb)
 494 {
 495         skb = vlan_insert_tag_set_proto(skb, skb->vlan_proto,
 496                                         skb_vlan_tag_get(skb));
 497         if (likely(skb))
 498                 __vlan_hwaccel_clear_tag(skb);
 499         return skb;
 500 }
 501 
 502 /**
 503  * __vlan_hwaccel_put_tag - hardware accelerated VLAN inserting
 504  * @skb: skbuff to tag
 505  * @vlan_proto: VLAN encapsulation protocol
 506  * @vlan_tci: VLAN TCI to insert
 507  *
 508  * Puts the VLAN TCI in @skb->vlan_tci and lets the device do the rest
 509  */
 510 static inline void __vlan_hwaccel_put_tag(struct sk_buff *skb,
 511                                           __be16 vlan_proto, u16 vlan_tci)
 512 {
 513         skb->vlan_proto = vlan_proto;
 514         skb->vlan_tci = vlan_tci;
 515         skb->vlan_present = 1;
 516 }
 517 
 518 /**
 519  * __vlan_get_tag - get the VLAN ID that is part of the payload
 520  * @skb: skbuff to query
 521  * @vlan_tci: buffer to store value
 522  *
 523  * Returns error if the skb is not of VLAN type
 524  */
 525 static inline int __vlan_get_tag(const struct sk_buff *skb, u16 *vlan_tci)
 526 {
 527         struct vlan_ethhdr *veth = (struct vlan_ethhdr *)skb->data;
 528 
 529         if (!eth_type_vlan(veth->h_vlan_proto))
 530                 return -EINVAL;
 531 
 532         *vlan_tci = ntohs(veth->h_vlan_TCI);
 533         return 0;
 534 }
 535 
 536 /**
 537  * __vlan_hwaccel_get_tag - get the VLAN ID that is in @skb->cb[]
 538  * @skb: skbuff to query
 539  * @vlan_tci: buffer to store value
 540  *
 541  * Returns error if @skb->vlan_tci is not set correctly
 542  */
 543 static inline int __vlan_hwaccel_get_tag(const struct sk_buff *skb,
 544                                          u16 *vlan_tci)
 545 {
 546         if (skb_vlan_tag_present(skb)) {
 547                 *vlan_tci = skb_vlan_tag_get(skb);
 548                 return 0;
 549         } else {
 550                 *vlan_tci = 0;
 551                 return -EINVAL;
 552         }
 553 }
 554 
 555 /**
 556  * vlan_get_tag - get the VLAN ID from the skb
 557  * @skb: skbuff to query
 558  * @vlan_tci: buffer to store value
 559  *
 560  * Returns error if the skb is not VLAN tagged
 561  */
 562 static inline int vlan_get_tag(const struct sk_buff *skb, u16 *vlan_tci)
 563 {
 564         if (skb->dev->features & NETIF_F_HW_VLAN_CTAG_TX) {
 565                 return __vlan_hwaccel_get_tag(skb, vlan_tci);
 566         } else {
 567                 return __vlan_get_tag(skb, vlan_tci);
 568         }
 569 }
 570 
 571 /**
 572  * vlan_get_protocol - get protocol EtherType.
 573  * @skb: skbuff to query
 574  * @type: first vlan protocol
 575  * @depth: buffer to store length of eth and vlan tags in bytes
 576  *
 577  * Returns the EtherType of the packet, regardless of whether it is
 578  * vlan encapsulated (normal or hardware accelerated) or not.
 579  */
 580 static inline __be16 __vlan_get_protocol(struct sk_buff *skb, __be16 type,
 581                                          int *depth)
 582 {
 583         unsigned int vlan_depth = skb->mac_len;
 584 
 585         /* if type is 802.1Q/AD then the header should already be
 586          * present at mac_len - VLAN_HLEN (if mac_len > 0), or at
 587          * ETH_HLEN otherwise
 588          */
 589         if (eth_type_vlan(type)) {
 590                 if (vlan_depth) {
 591                         if (WARN_ON(vlan_depth < VLAN_HLEN))
 592                                 return 0;
 593                         vlan_depth -= VLAN_HLEN;
 594                 } else {
 595                         vlan_depth = ETH_HLEN;
 596                 }
 597                 do {
 598                         struct vlan_hdr *vh;
 599 
 600                         if (unlikely(!pskb_may_pull(skb,
 601                                                     vlan_depth + VLAN_HLEN)))
 602                                 return 0;
 603 
 604                         vh = (struct vlan_hdr *)(skb->data + vlan_depth);
 605                         type = vh->h_vlan_encapsulated_proto;
 606                         vlan_depth += VLAN_HLEN;
 607                 } while (eth_type_vlan(type));
 608         }
 609 
 610         if (depth)
 611                 *depth = vlan_depth;
 612 
 613         return type;
 614 }
 615 
 616 /**
 617  * vlan_get_protocol - get protocol EtherType.
 618  * @skb: skbuff to query
 619  *
 620  * Returns the EtherType of the packet, regardless of whether it is
 621  * vlan encapsulated (normal or hardware accelerated) or not.
 622  */
 623 static inline __be16 vlan_get_protocol(struct sk_buff *skb)
 624 {
 625         return __vlan_get_protocol(skb, skb->protocol, NULL);
 626 }
 627 
 628 static inline void vlan_set_encap_proto(struct sk_buff *skb,
 629                                         struct vlan_hdr *vhdr)
 630 {
 631         __be16 proto;
 632         unsigned short *rawp;
 633 
 634         /*
 635          * Was a VLAN packet, grab the encapsulated protocol, which the layer
 636          * three protocols care about.
 637          */
 638 
 639         proto = vhdr->h_vlan_encapsulated_proto;
 640         if (eth_proto_is_802_3(proto)) {
 641                 skb->protocol = proto;
 642                 return;
 643         }
 644 
 645         rawp = (unsigned short *)(vhdr + 1);
 646         if (*rawp == 0xFFFF)
 647                 /*
 648                  * This is a magic hack to spot IPX packets. Older Novell
 649                  * breaks the protocol design and runs IPX over 802.3 without
 650                  * an 802.2 LLC layer. We look for FFFF which isn't a used
 651                  * 802.2 SSAP/DSAP. This won't work for fault tolerant netware
 652                  * but does for the rest.
 653                  */
 654                 skb->protocol = htons(ETH_P_802_3);
 655         else
 656                 /*
 657                  * Real 802.2 LLC
 658                  */
 659                 skb->protocol = htons(ETH_P_802_2);
 660 }
 661 
 662 /**
 663  * skb_vlan_tagged - check if skb is vlan tagged.
 664  * @skb: skbuff to query
 665  *
 666  * Returns true if the skb is tagged, regardless of whether it is hardware
 667  * accelerated or not.
 668  */
 669 static inline bool skb_vlan_tagged(const struct sk_buff *skb)
 670 {
 671         if (!skb_vlan_tag_present(skb) &&
 672             likely(!eth_type_vlan(skb->protocol)))
 673                 return false;
 674 
 675         return true;
 676 }
 677 
 678 /**
 679  * skb_vlan_tagged_multi - check if skb is vlan tagged with multiple headers.
 680  * @skb: skbuff to query
 681  *
 682  * Returns true if the skb is tagged with multiple vlan headers, regardless
 683  * of whether it is hardware accelerated or not.
 684  */
 685 static inline bool skb_vlan_tagged_multi(struct sk_buff *skb)
 686 {
 687         __be16 protocol = skb->protocol;
 688 
 689         if (!skb_vlan_tag_present(skb)) {
 690                 struct vlan_ethhdr *veh;
 691 
 692                 if (likely(!eth_type_vlan(protocol)))
 693                         return false;
 694 
 695                 if (unlikely(!pskb_may_pull(skb, VLAN_ETH_HLEN)))
 696                         return false;
 697 
 698                 veh = (struct vlan_ethhdr *)skb->data;
 699                 protocol = veh->h_vlan_encapsulated_proto;
 700         }
 701 
 702         if (!eth_type_vlan(protocol))
 703                 return false;
 704 
 705         return true;
 706 }
 707 
 708 /**
 709  * vlan_features_check - drop unsafe features for skb with multiple tags.
 710  * @skb: skbuff to query
 711  * @features: features to be checked
 712  *
 713  * Returns features without unsafe ones if the skb has multiple tags.
 714  */
 715 static inline netdev_features_t vlan_features_check(struct sk_buff *skb,
 716                                                     netdev_features_t features)
 717 {
 718         if (skb_vlan_tagged_multi(skb)) {
 719                 /* In the case of multi-tagged packets, use a direct mask
 720                  * instead of using netdev_interesect_features(), to make
 721                  * sure that only devices supporting NETIF_F_HW_CSUM will
 722                  * have checksum offloading support.
 723                  */
 724                 features &= NETIF_F_SG | NETIF_F_HIGHDMA | NETIF_F_HW_CSUM |
 725                             NETIF_F_FRAGLIST | NETIF_F_HW_VLAN_CTAG_TX |
 726                             NETIF_F_HW_VLAN_STAG_TX;
 727         }
 728 
 729         return features;
 730 }
 731 
 732 /**
 733  * compare_vlan_header - Compare two vlan headers
 734  * @h1: Pointer to vlan header
 735  * @h2: Pointer to vlan header
 736  *
 737  * Compare two vlan headers, returns 0 if equal.
 738  *
 739  * Please note that alignment of h1 & h2 are only guaranteed to be 16 bits.
 740  */
 741 static inline unsigned long compare_vlan_header(const struct vlan_hdr *h1,
 742                                                 const struct vlan_hdr *h2)
 743 {
 744 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
 745         return *(u32 *)h1 ^ *(u32 *)h2;
 746 #else
 747         return ((__force u32)h1->h_vlan_TCI ^ (__force u32)h2->h_vlan_TCI) |
 748                ((__force u32)h1->h_vlan_encapsulated_proto ^
 749                 (__force u32)h2->h_vlan_encapsulated_proto);
 750 #endif
 751 }
 752 #endif /* !(_LINUX_IF_VLAN_H_) */