xref: /linux/include/linux/if_vlan.h (revision b889fcf63cb62e7fdb7816565e28f44dbe4a76a5)
1 /*
2  * VLAN		An implementation of 802.1Q VLAN tagging.
3  *
4  * Authors:	Ben Greear <greearb@candelatech.com>
5  *
6  *		This program is free software; you can redistribute it and/or
7  *		modify it under the terms of the GNU General Public License
8  *		as published by the Free Software Foundation; either version
9  *		2 of the License, or (at your option) any later version.
10  *
11  */
12 #ifndef _LINUX_IF_VLAN_H_
13 #define _LINUX_IF_VLAN_H_
14 
15 #include <linux/netdevice.h>
16 #include <linux/etherdevice.h>
17 #include <linux/rtnetlink.h>
18 #include <linux/bug.h>
19 #include <uapi/linux/if_vlan.h>
20 
21 #define VLAN_HLEN	4		/* The additional bytes required by VLAN
22 					 * (in addition to the Ethernet header)
23 					 */
24 #define VLAN_ETH_HLEN	18		/* Total octets in header.	 */
25 #define VLAN_ETH_ZLEN	64		/* Min. octets in frame sans FCS */
26 
27 /*
28  * According to 802.3ac, the packet can be 4 bytes longer. --Klika Jan
29  */
30 #define VLAN_ETH_DATA_LEN	1500	/* Max. octets in payload	 */
31 #define VLAN_ETH_FRAME_LEN	1518	/* Max. octets in frame sans FCS */
32 
33 /*
34  * 	struct vlan_hdr - vlan header
35  * 	@h_vlan_TCI: priority and VLAN ID
36  *	@h_vlan_encapsulated_proto: packet type ID or len
37  */
38 struct vlan_hdr {
39 	__be16	h_vlan_TCI;
40 	__be16	h_vlan_encapsulated_proto;
41 };
42 
43 /**
44  *	struct vlan_ethhdr - vlan ethernet header (ethhdr + vlan_hdr)
45  *	@h_dest: destination ethernet address
46  *	@h_source: source ethernet address
47  *	@h_vlan_proto: ethernet protocol (always 0x8100)
48  *	@h_vlan_TCI: priority and VLAN ID
49  *	@h_vlan_encapsulated_proto: packet type ID or len
50  */
51 struct vlan_ethhdr {
52 	unsigned char	h_dest[ETH_ALEN];
53 	unsigned char	h_source[ETH_ALEN];
54 	__be16		h_vlan_proto;
55 	__be16		h_vlan_TCI;
56 	__be16		h_vlan_encapsulated_proto;
57 };
58 
59 #include <linux/skbuff.h>
60 
61 static inline struct vlan_ethhdr *vlan_eth_hdr(const struct sk_buff *skb)
62 {
63 	return (struct vlan_ethhdr *)skb_mac_header(skb);
64 }
65 
66 #define VLAN_PRIO_MASK		0xe000 /* Priority Code Point */
67 #define VLAN_PRIO_SHIFT		13
68 #define VLAN_CFI_MASK		0x1000 /* Canonical Format Indicator */
69 #define VLAN_TAG_PRESENT	VLAN_CFI_MASK
70 #define VLAN_VID_MASK		0x0fff /* VLAN Identifier */
71 #define VLAN_N_VID		4096
72 
73 /* found in socket.c */
74 extern void vlan_ioctl_set(int (*hook)(struct net *, void __user *));
75 
76 static inline int is_vlan_dev(struct net_device *dev)
77 {
78         return dev->priv_flags & IFF_802_1Q_VLAN;
79 }
80 
81 #define vlan_tx_tag_present(__skb)	((__skb)->vlan_tci & VLAN_TAG_PRESENT)
82 #define vlan_tx_nonzero_tag_present(__skb) \
83 	(vlan_tx_tag_present(__skb) && ((__skb)->vlan_tci & VLAN_VID_MASK))
84 #define vlan_tx_tag_get(__skb)		((__skb)->vlan_tci & ~VLAN_TAG_PRESENT)
85 
86 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
87 
88 extern struct net_device *__vlan_find_dev_deep(struct net_device *real_dev,
89 					       u16 vlan_id);
90 extern struct net_device *vlan_dev_real_dev(const struct net_device *dev);
91 extern u16 vlan_dev_vlan_id(const struct net_device *dev);
92 
93 extern bool vlan_do_receive(struct sk_buff **skb);
94 extern struct sk_buff *vlan_untag(struct sk_buff *skb);
95 
96 extern int vlan_vid_add(struct net_device *dev, unsigned short vid);
97 extern void vlan_vid_del(struct net_device *dev, unsigned short vid);
98 
99 extern int vlan_vids_add_by_dev(struct net_device *dev,
100 				const struct net_device *by_dev);
101 extern void vlan_vids_del_by_dev(struct net_device *dev,
102 				 const struct net_device *by_dev);
103 
104 extern bool vlan_uses_dev(const struct net_device *dev);
105 #else
106 static inline struct net_device *
107 __vlan_find_dev_deep(struct net_device *real_dev, u16 vlan_id)
108 {
109 	return NULL;
110 }
111 
112 static inline struct net_device *vlan_dev_real_dev(const struct net_device *dev)
113 {
114 	BUG();
115 	return NULL;
116 }
117 
118 static inline u16 vlan_dev_vlan_id(const struct net_device *dev)
119 {
120 	BUG();
121 	return 0;
122 }
123 
124 static inline bool vlan_do_receive(struct sk_buff **skb)
125 {
126 	return false;
127 }
128 
129 static inline struct sk_buff *vlan_untag(struct sk_buff *skb)
130 {
131 	return skb;
132 }
133 
134 static inline int vlan_vid_add(struct net_device *dev, unsigned short vid)
135 {
136 	return 0;
137 }
138 
139 static inline void vlan_vid_del(struct net_device *dev, unsigned short vid)
140 {
141 }
142 
143 static inline int vlan_vids_add_by_dev(struct net_device *dev,
144 				       const struct net_device *by_dev)
145 {
146 	return 0;
147 }
148 
149 static inline void vlan_vids_del_by_dev(struct net_device *dev,
150 					const struct net_device *by_dev)
151 {
152 }
153 
154 static inline bool vlan_uses_dev(const struct net_device *dev)
155 {
156 	return false;
157 }
158 #endif
159 
160 /**
161  * vlan_insert_tag - regular VLAN tag inserting
162  * @skb: skbuff to tag
163  * @vlan_tci: VLAN TCI to insert
164  *
165  * Inserts the VLAN tag into @skb as part of the payload
166  * Returns a VLAN tagged skb. If a new skb is created, @skb is freed.
167  *
168  * Following the skb_unshare() example, in case of error, the calling function
169  * doesn't have to worry about freeing the original skb.
170  *
171  * Does not change skb->protocol so this function can be used during receive.
172  */
173 static inline struct sk_buff *vlan_insert_tag(struct sk_buff *skb, u16 vlan_tci)
174 {
175 	struct vlan_ethhdr *veth;
176 
177 	if (skb_cow_head(skb, VLAN_HLEN) < 0) {
178 		kfree_skb(skb);
179 		return NULL;
180 	}
181 	veth = (struct vlan_ethhdr *)skb_push(skb, VLAN_HLEN);
182 
183 	/* Move the mac addresses to the beginning of the new header. */
184 	memmove(skb->data, skb->data + VLAN_HLEN, 2 * ETH_ALEN);
185 	skb->mac_header -= VLAN_HLEN;
186 
187 	/* first, the ethernet type */
188 	veth->h_vlan_proto = htons(ETH_P_8021Q);
189 
190 	/* now, the TCI */
191 	veth->h_vlan_TCI = htons(vlan_tci);
192 
193 	return skb;
194 }
195 
196 /**
197  * __vlan_put_tag - regular VLAN tag inserting
198  * @skb: skbuff to tag
199  * @vlan_tci: VLAN TCI to insert
200  *
201  * Inserts the VLAN tag into @skb as part of the payload
202  * Returns a VLAN tagged skb. If a new skb is created, @skb is freed.
203  *
204  * Following the skb_unshare() example, in case of error, the calling function
205  * doesn't have to worry about freeing the original skb.
206  */
207 static inline struct sk_buff *__vlan_put_tag(struct sk_buff *skb, u16 vlan_tci)
208 {
209 	skb = vlan_insert_tag(skb, vlan_tci);
210 	if (skb)
211 		skb->protocol = htons(ETH_P_8021Q);
212 	return skb;
213 }
214 
215 /**
216  * __vlan_hwaccel_put_tag - hardware accelerated VLAN inserting
217  * @skb: skbuff to tag
218  * @vlan_tci: VLAN TCI to insert
219  *
220  * Puts the VLAN TCI in @skb->vlan_tci and lets the device do the rest
221  */
222 static inline struct sk_buff *__vlan_hwaccel_put_tag(struct sk_buff *skb,
223 						     u16 vlan_tci)
224 {
225 	skb->vlan_tci = VLAN_TAG_PRESENT | vlan_tci;
226 	return skb;
227 }
228 
229 #define HAVE_VLAN_PUT_TAG
230 
231 /**
232  * vlan_put_tag - inserts VLAN tag according to device features
233  * @skb: skbuff to tag
234  * @vlan_tci: VLAN TCI to insert
235  *
236  * Assumes skb->dev is the target that will xmit this frame.
237  * Returns a VLAN tagged skb.
238  */
239 static inline struct sk_buff *vlan_put_tag(struct sk_buff *skb, u16 vlan_tci)
240 {
241 	if (skb->dev->features & NETIF_F_HW_VLAN_TX) {
242 		return __vlan_hwaccel_put_tag(skb, vlan_tci);
243 	} else {
244 		return __vlan_put_tag(skb, vlan_tci);
245 	}
246 }
247 
248 /**
249  * __vlan_get_tag - get the VLAN ID that is part of the payload
250  * @skb: skbuff to query
251  * @vlan_tci: buffer to store vlaue
252  *
253  * Returns error if the skb is not of VLAN type
254  */
255 static inline int __vlan_get_tag(const struct sk_buff *skb, u16 *vlan_tci)
256 {
257 	struct vlan_ethhdr *veth = (struct vlan_ethhdr *)skb->data;
258 
259 	if (veth->h_vlan_proto != htons(ETH_P_8021Q)) {
260 		return -EINVAL;
261 	}
262 
263 	*vlan_tci = ntohs(veth->h_vlan_TCI);
264 	return 0;
265 }
266 
267 /**
268  * __vlan_hwaccel_get_tag - get the VLAN ID that is in @skb->cb[]
269  * @skb: skbuff to query
270  * @vlan_tci: buffer to store vlaue
271  *
272  * Returns error if @skb->vlan_tci is not set correctly
273  */
274 static inline int __vlan_hwaccel_get_tag(const struct sk_buff *skb,
275 					 u16 *vlan_tci)
276 {
277 	if (vlan_tx_tag_present(skb)) {
278 		*vlan_tci = vlan_tx_tag_get(skb);
279 		return 0;
280 	} else {
281 		*vlan_tci = 0;
282 		return -EINVAL;
283 	}
284 }
285 
286 #define HAVE_VLAN_GET_TAG
287 
288 /**
289  * vlan_get_tag - get the VLAN ID from the skb
290  * @skb: skbuff to query
291  * @vlan_tci: buffer to store vlaue
292  *
293  * Returns error if the skb is not VLAN tagged
294  */
295 static inline int vlan_get_tag(const struct sk_buff *skb, u16 *vlan_tci)
296 {
297 	if (skb->dev->features & NETIF_F_HW_VLAN_TX) {
298 		return __vlan_hwaccel_get_tag(skb, vlan_tci);
299 	} else {
300 		return __vlan_get_tag(skb, vlan_tci);
301 	}
302 }
303 
304 /**
305  * vlan_get_protocol - get protocol EtherType.
306  * @skb: skbuff to query
307  *
308  * Returns the EtherType of the packet, regardless of whether it is
309  * vlan encapsulated (normal or hardware accelerated) or not.
310  */
311 static inline __be16 vlan_get_protocol(const struct sk_buff *skb)
312 {
313 	__be16 protocol = 0;
314 
315 	if (vlan_tx_tag_present(skb) ||
316 	     skb->protocol != cpu_to_be16(ETH_P_8021Q))
317 		protocol = skb->protocol;
318 	else {
319 		__be16 proto, *protop;
320 		protop = skb_header_pointer(skb, offsetof(struct vlan_ethhdr,
321 						h_vlan_encapsulated_proto),
322 						sizeof(proto), &proto);
323 		if (likely(protop))
324 			protocol = *protop;
325 	}
326 
327 	return protocol;
328 }
329 
330 static inline void vlan_set_encap_proto(struct sk_buff *skb,
331 					struct vlan_hdr *vhdr)
332 {
333 	__be16 proto;
334 	unsigned char *rawp;
335 
336 	/*
337 	 * Was a VLAN packet, grab the encapsulated protocol, which the layer
338 	 * three protocols care about.
339 	 */
340 
341 	proto = vhdr->h_vlan_encapsulated_proto;
342 	if (ntohs(proto) >= 1536) {
343 		skb->protocol = proto;
344 		return;
345 	}
346 
347 	rawp = skb->data;
348 	if (*(unsigned short *) rawp == 0xFFFF)
349 		/*
350 		 * This is a magic hack to spot IPX packets. Older Novell
351 		 * breaks the protocol design and runs IPX over 802.3 without
352 		 * an 802.2 LLC layer. We look for FFFF which isn't a used
353 		 * 802.2 SSAP/DSAP. This won't work for fault tolerant netware
354 		 * but does for the rest.
355 		 */
356 		skb->protocol = htons(ETH_P_802_3);
357 	else
358 		/*
359 		 * Real 802.2 LLC
360 		 */
361 		skb->protocol = htons(ETH_P_802_2);
362 }
363 #endif /* !(_LINUX_IF_VLAN_H_) */
364