2 * Definitions for the 'struct sk_buff' memory handlers.
5 * Alan Cox, <gw4pts@gw4pts.ampr.org>
6 * Florian La Roche, <rzsfl@rz.uni-sb.de>
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
14 #ifndef _LINUX_SKBUFF_H
15 #define _LINUX_SKBUFF_H
17 #include <linux/kernel.h>
18 #include <linux/compiler.h>
19 #include <linux/time.h>
20 #include <linux/cache.h>
22 #include <asm/atomic.h>
23 #include <asm/types.h>
24 #include <linux/spinlock.h>
25 #include <linux/net.h>
26 #include <linux/textsearch.h>
27 #include <net/checksum.h>
28 #include <linux/rcupdate.h>
29 #include <linux/dmaengine.h>
30 #include <linux/hrtimer.h>
32 #define HAVE_ALLOC_SKB /* For the drivers to know */
33 #define HAVE_ALIGNABLE_SKB /* Ditto 8) */
35 #define CHECKSUM_NONE 0
36 #define CHECKSUM_PARTIAL 1
37 #define CHECKSUM_UNNECESSARY 2
38 #define CHECKSUM_COMPLETE 3
40 #define SKB_DATA_ALIGN(X) (((X) + (SMP_CACHE_BYTES - 1)) & \
41 ~(SMP_CACHE_BYTES - 1))
42 #define SKB_WITH_OVERHEAD(X) \
43 (((X) - sizeof(struct skb_shared_info)) & \
44 ~(SMP_CACHE_BYTES - 1))
45 #define SKB_MAX_ORDER(X, ORDER) \
46 SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
47 #define SKB_MAX_HEAD(X) (SKB_MAX_ORDER((X), 0))
48 #define SKB_MAX_ALLOC (SKB_MAX_ORDER(0, 2))
50 /* A. Checksumming of received packets by device.
52 * NONE: device failed to checksum this packet.
53 * skb->csum is undefined.
55 * UNNECESSARY: device parsed packet and wouldbe verified checksum.
56 * skb->csum is undefined.
57 * It is bad option, but, unfortunately, many of vendors do this.
58 * Apparently with secret goal to sell you new device, when you
59 * will add new protocol to your host. F.e. IPv6. 8)
61 * COMPLETE: the most generic way. Device supplied checksum of _all_
62 * the packet as seen by netif_rx in skb->csum.
63 * NOTE: Even if device supports only some protocols, but
64 * is able to produce some skb->csum, it MUST use COMPLETE,
67 * B. Checksumming on output.
69 * NONE: skb is checksummed by protocol or csum is not required.
71 * PARTIAL: device is required to csum packet as seen by hard_start_xmit
72 * from skb->transport_header to the end and to record the checksum
73 * at skb->transport_header + skb->csum.
75 * Device must show its capabilities in dev->features, set
76 * at device setup time.
77 * NETIF_F_HW_CSUM - it is clever device, it is able to checksum
79 * NETIF_F_NO_CSUM - loopback or reliable single hop media.
80 * NETIF_F_IP_CSUM - device is dumb. It is able to csum only
81 * TCP/UDP over IPv4. Sigh. Vendors like this
82 * way by an unknown reason. Though, see comment above
83 * about CHECKSUM_UNNECESSARY. 8)
85 * Any questions? No questions, good. --ANK
91 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
97 #ifdef CONFIG_BRIDGE_NETFILTER
98 struct nf_bridge_info {
100 struct net_device *physindev;
101 struct net_device *physoutdev;
102 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
103 struct net_device *netoutdev;
106 unsigned long data[32 / sizeof(unsigned long)];
110 struct sk_buff_head {
111 /* These two members must be first. */
112 struct sk_buff *next;
113 struct sk_buff *prev;
121 /* To allow 64K frame to be packed as single skb without frag_list */
122 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 2)
124 typedef struct skb_frag_struct skb_frag_t;
126 struct skb_frag_struct {
132 /* This data is invariant across clones and lives at
133 * the end of the header data, ie. at skb->end.
135 struct skb_shared_info {
137 unsigned short nr_frags;
138 unsigned short gso_size;
139 /* Warning: this field is not always filled in (UFO)! */
140 unsigned short gso_segs;
141 unsigned short gso_type;
143 struct sk_buff *frag_list;
144 skb_frag_t frags[MAX_SKB_FRAGS];
147 /* We divide dataref into two halves. The higher 16 bits hold references
148 * to the payload part of skb->data. The lower 16 bits hold references to
149 * the entire skb->data. It is up to the users of the skb to agree on
150 * where the payload starts.
152 * All users must obey the rule that the skb->data reference count must be
153 * greater than or equal to the payload reference count.
155 * Holding a reference to the payload part means that the user does not
156 * care about modifications to the header part of skb->data.
158 #define SKB_DATAREF_SHIFT 16
159 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
163 SKB_FCLONE_UNAVAILABLE,
169 SKB_GSO_TCPV4 = 1 << 0,
170 SKB_GSO_UDP = 1 << 1,
172 /* This indicates the skb is from an untrusted source. */
173 SKB_GSO_DODGY = 1 << 2,
175 /* This indicates the tcp segment has CWR set. */
176 SKB_GSO_TCP_ECN = 1 << 3,
178 SKB_GSO_TCPV6 = 1 << 4,
181 #if BITS_PER_LONG > 32
182 #define NET_SKBUFF_DATA_USES_OFFSET 1
185 #ifdef NET_SKBUFF_DATA_USES_OFFSET
186 typedef unsigned int sk_buff_data_t;
188 typedef unsigned char *sk_buff_data_t;
192 * struct sk_buff - socket buffer
193 * @next: Next buffer in list
194 * @prev: Previous buffer in list
195 * @sk: Socket we are owned by
196 * @tstamp: Time we arrived
197 * @dev: Device we arrived on/are leaving by
198 * @iif: ifindex of device we arrived on
199 * @h: Transport layer header
200 * @network_header: Network layer header
201 * @mac_header: Link layer header
202 * @dst: destination entry
203 * @sp: the security path, used for xfrm
204 * @cb: Control buffer. Free for use by every layer. Put private vars here
205 * @len: Length of actual data
206 * @data_len: Data length
207 * @mac_len: Length of link layer header
208 * @csum: Checksum (must include start/offset pair)
209 * @csum_start: Offset from skb->head where checksumming should start
210 * @csum_offset: Offset from csum_start where checksum should be stored
211 * @local_df: allow local fragmentation
212 * @cloned: Head may be cloned (check refcnt to be sure)
213 * @nohdr: Payload reference only, must not modify header
214 * @pkt_type: Packet class
215 * @fclone: skbuff clone status
216 * @ip_summed: Driver fed us an IP checksum
217 * @priority: Packet queueing priority
218 * @users: User count - see {datagram,tcp}.c
219 * @protocol: Packet protocol from driver
220 * @truesize: Buffer size
221 * @head: Head of buffer
222 * @data: Data head pointer
223 * @tail: Tail pointer
225 * @destructor: Destruct function
226 * @mark: Generic packet mark
227 * @nfct: Associated connection, if any
228 * @ipvs_property: skbuff is owned by ipvs
229 * @nfctinfo: Relationship of this skb to the connection
230 * @nfct_reasm: netfilter conntrack re-assembly pointer
231 * @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
232 * @tc_index: Traffic control index
233 * @tc_verd: traffic control verdict
234 * @dma_cookie: a cookie to one of several possible DMA operations
235 * done by skb DMA functions
236 * @secmark: security marking
240 /* These two members must be first. */
241 struct sk_buff *next;
242 struct sk_buff *prev;
246 struct net_device *dev;
248 /* 4 byte hole on 64 bit*/
250 struct dst_entry *dst;
254 * This is the control buffer. It is free to use for every
255 * layer. Please put your private variables there. If you
256 * want to keep them across layers you have to do a skb_clone()
257 * first. This is owned by whoever has the skb queued ATM.
282 void (*destructor)(struct sk_buff *skb);
283 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
284 struct nf_conntrack *nfct;
285 struct sk_buff *nfct_reasm;
287 #ifdef CONFIG_BRIDGE_NETFILTER
288 struct nf_bridge_info *nf_bridge;
290 #ifdef CONFIG_NET_SCHED
291 __u16 tc_index; /* traffic control index */
292 #ifdef CONFIG_NET_CLS_ACT
293 __u16 tc_verd; /* traffic control verdict */
296 #ifdef CONFIG_NET_DMA
297 dma_cookie_t dma_cookie;
299 #ifdef CONFIG_NETWORK_SECMARK
305 sk_buff_data_t transport_header;
306 sk_buff_data_t network_header;
307 sk_buff_data_t mac_header;
308 /* These elements must be at the end, see alloc_skb() for details. */
313 unsigned int truesize;
319 * Handling routines are only of interest to the kernel
321 #include <linux/slab.h>
323 #include <asm/system.h>
325 extern void kfree_skb(struct sk_buff *skb);
326 extern void __kfree_skb(struct sk_buff *skb);
327 extern struct sk_buff *__alloc_skb(unsigned int size,
328 gfp_t priority, int fclone, int node);
329 static inline struct sk_buff *alloc_skb(unsigned int size,
332 return __alloc_skb(size, priority, 0, -1);
335 static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
338 return __alloc_skb(size, priority, 1, -1);
341 extern void kfree_skbmem(struct sk_buff *skb);
342 extern struct sk_buff *skb_clone(struct sk_buff *skb,
344 extern struct sk_buff *skb_copy(const struct sk_buff *skb,
346 extern struct sk_buff *pskb_copy(struct sk_buff *skb,
348 extern int pskb_expand_head(struct sk_buff *skb,
349 int nhead, int ntail,
351 extern struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
352 unsigned int headroom);
353 extern struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
354 int newheadroom, int newtailroom,
356 extern int skb_to_sgvec(struct sk_buff *skb,
357 struct scatterlist *sg, int offset,
359 extern int skb_cow_data(struct sk_buff *skb, int tailbits,
360 struct sk_buff **trailer);
361 extern int skb_pad(struct sk_buff *skb, int pad);
362 #define dev_kfree_skb(a) kfree_skb(a)
363 extern void skb_over_panic(struct sk_buff *skb, int len,
365 extern void skb_under_panic(struct sk_buff *skb, int len,
367 extern void skb_truesize_bug(struct sk_buff *skb);
369 static inline void skb_truesize_check(struct sk_buff *skb)
371 if (unlikely((int)skb->truesize < sizeof(struct sk_buff) + skb->len))
372 skb_truesize_bug(skb);
375 extern int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
376 int getfrag(void *from, char *to, int offset,
377 int len,int odd, struct sk_buff *skb),
378 void *from, int length);
385 __u32 stepped_offset;
386 struct sk_buff *root_skb;
387 struct sk_buff *cur_skb;
391 extern void skb_prepare_seq_read(struct sk_buff *skb,
392 unsigned int from, unsigned int to,
393 struct skb_seq_state *st);
394 extern unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
395 struct skb_seq_state *st);
396 extern void skb_abort_seq_read(struct skb_seq_state *st);
398 extern unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
399 unsigned int to, struct ts_config *config,
400 struct ts_state *state);
402 #ifdef NET_SKBUFF_DATA_USES_OFFSET
403 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
405 return skb->head + skb->end;
408 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
415 #define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
418 * skb_queue_empty - check if a queue is empty
421 * Returns true if the queue is empty, false otherwise.
423 static inline int skb_queue_empty(const struct sk_buff_head *list)
425 return list->next == (struct sk_buff *)list;
429 * skb_get - reference buffer
430 * @skb: buffer to reference
432 * Makes another reference to a socket buffer and returns a pointer
435 static inline struct sk_buff *skb_get(struct sk_buff *skb)
437 atomic_inc(&skb->users);
442 * If users == 1, we are the only owner and are can avoid redundant
447 * skb_cloned - is the buffer a clone
448 * @skb: buffer to check
450 * Returns true if the buffer was generated with skb_clone() and is
451 * one of multiple shared copies of the buffer. Cloned buffers are
452 * shared data so must not be written to under normal circumstances.
454 static inline int skb_cloned(const struct sk_buff *skb)
456 return skb->cloned &&
457 (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
461 * skb_header_cloned - is the header a clone
462 * @skb: buffer to check
464 * Returns true if modifying the header part of the buffer requires
465 * the data to be copied.
467 static inline int skb_header_cloned(const struct sk_buff *skb)
474 dataref = atomic_read(&skb_shinfo(skb)->dataref);
475 dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
480 * skb_header_release - release reference to header
481 * @skb: buffer to operate on
483 * Drop a reference to the header part of the buffer. This is done
484 * by acquiring a payload reference. You must not read from the header
485 * part of skb->data after this.
487 static inline void skb_header_release(struct sk_buff *skb)
491 atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
495 * skb_shared - is the buffer shared
496 * @skb: buffer to check
498 * Returns true if more than one person has a reference to this
501 static inline int skb_shared(const struct sk_buff *skb)
503 return atomic_read(&skb->users) != 1;
507 * skb_share_check - check if buffer is shared and if so clone it
508 * @skb: buffer to check
509 * @pri: priority for memory allocation
511 * If the buffer is shared the buffer is cloned and the old copy
512 * drops a reference. A new clone with a single reference is returned.
513 * If the buffer is not shared the original buffer is returned. When
514 * being called from interrupt status or with spinlocks held pri must
517 * NULL is returned on a memory allocation failure.
519 static inline struct sk_buff *skb_share_check(struct sk_buff *skb,
522 might_sleep_if(pri & __GFP_WAIT);
523 if (skb_shared(skb)) {
524 struct sk_buff *nskb = skb_clone(skb, pri);
532 * Copy shared buffers into a new sk_buff. We effectively do COW on
533 * packets to handle cases where we have a local reader and forward
534 * and a couple of other messy ones. The normal one is tcpdumping
535 * a packet thats being forwarded.
539 * skb_unshare - make a copy of a shared buffer
540 * @skb: buffer to check
541 * @pri: priority for memory allocation
543 * If the socket buffer is a clone then this function creates a new
544 * copy of the data, drops a reference count on the old copy and returns
545 * the new copy with the reference count at 1. If the buffer is not a clone
546 * the original buffer is returned. When called with a spinlock held or
547 * from interrupt state @pri must be %GFP_ATOMIC
549 * %NULL is returned on a memory allocation failure.
551 static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
554 might_sleep_if(pri & __GFP_WAIT);
555 if (skb_cloned(skb)) {
556 struct sk_buff *nskb = skb_copy(skb, pri);
557 kfree_skb(skb); /* Free our shared copy */
565 * @list_: list to peek at
567 * Peek an &sk_buff. Unlike most other operations you _MUST_
568 * be careful with this one. A peek leaves the buffer on the
569 * list and someone else may run off with it. You must hold
570 * the appropriate locks or have a private queue to do this.
572 * Returns %NULL for an empty list or a pointer to the head element.
573 * The reference count is not incremented and the reference is therefore
574 * volatile. Use with caution.
576 static inline struct sk_buff *skb_peek(struct sk_buff_head *list_)
578 struct sk_buff *list = ((struct sk_buff *)list_)->next;
579 if (list == (struct sk_buff *)list_)
586 * @list_: list to peek at
588 * Peek an &sk_buff. Unlike most other operations you _MUST_
589 * be careful with this one. A peek leaves the buffer on the
590 * list and someone else may run off with it. You must hold
591 * the appropriate locks or have a private queue to do this.
593 * Returns %NULL for an empty list or a pointer to the tail element.
594 * The reference count is not incremented and the reference is therefore
595 * volatile. Use with caution.
597 static inline struct sk_buff *skb_peek_tail(struct sk_buff_head *list_)
599 struct sk_buff *list = ((struct sk_buff *)list_)->prev;
600 if (list == (struct sk_buff *)list_)
606 * skb_queue_len - get queue length
607 * @list_: list to measure
609 * Return the length of an &sk_buff queue.
611 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
617 * This function creates a split out lock class for each invocation;
618 * this is needed for now since a whole lot of users of the skb-queue
619 * infrastructure in drivers have different locking usage (in hardirq)
620 * than the networking core (in softirq only). In the long run either the
621 * network layer or drivers should need annotation to consolidate the
622 * main types of usage into 3 classes.
624 static inline void skb_queue_head_init(struct sk_buff_head *list)
626 spin_lock_init(&list->lock);
627 list->prev = list->next = (struct sk_buff *)list;
631 static inline void skb_queue_head_init_class(struct sk_buff_head *list,
632 struct lock_class_key *class)
634 skb_queue_head_init(list);
635 lockdep_set_class(&list->lock, class);
639 * Insert an sk_buff at the start of a list.
641 * The "__skb_xxxx()" functions are the non-atomic ones that
642 * can only be called with interrupts disabled.
646 * __skb_queue_after - queue a buffer at the list head
648 * @prev: place after this buffer
649 * @newsk: buffer to queue
651 * Queue a buffer int the middle of a list. This function takes no locks
652 * and you must therefore hold required locks before calling it.
654 * A buffer cannot be placed on two lists at the same time.
656 static inline void __skb_queue_after(struct sk_buff_head *list,
657 struct sk_buff *prev,
658 struct sk_buff *newsk)
660 struct sk_buff *next;
666 next->prev = prev->next = newsk;
670 * __skb_queue_head - queue a buffer at the list head
672 * @newsk: buffer to queue
674 * Queue a buffer at the start of a list. This function takes no locks
675 * and you must therefore hold required locks before calling it.
677 * A buffer cannot be placed on two lists at the same time.
679 extern void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
680 static inline void __skb_queue_head(struct sk_buff_head *list,
681 struct sk_buff *newsk)
683 __skb_queue_after(list, (struct sk_buff *)list, newsk);
687 * __skb_queue_tail - queue a buffer at the list tail
689 * @newsk: buffer to queue
691 * Queue a buffer at the end of a list. This function takes no locks
692 * and you must therefore hold required locks before calling it.
694 * A buffer cannot be placed on two lists at the same time.
696 extern void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
697 static inline void __skb_queue_tail(struct sk_buff_head *list,
698 struct sk_buff *newsk)
700 struct sk_buff *prev, *next;
703 next = (struct sk_buff *)list;
707 next->prev = prev->next = newsk;
712 * __skb_dequeue - remove from the head of the queue
713 * @list: list to dequeue from
715 * Remove the head of the list. This function does not take any locks
716 * so must be used with appropriate locks held only. The head item is
717 * returned or %NULL if the list is empty.
719 extern struct sk_buff *skb_dequeue(struct sk_buff_head *list);
720 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
722 struct sk_buff *next, *prev, *result;
724 prev = (struct sk_buff *) list;
733 result->next = result->prev = NULL;
740 * Insert a packet on a list.
742 extern void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list);
743 static inline void __skb_insert(struct sk_buff *newsk,
744 struct sk_buff *prev, struct sk_buff *next,
745 struct sk_buff_head *list)
749 next->prev = prev->next = newsk;
754 * Place a packet after a given packet in a list.
756 extern void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list);
757 static inline void __skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
759 __skb_insert(newsk, old, old->next, list);
763 * remove sk_buff from list. _Must_ be called atomically, and with
766 extern void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);
767 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
769 struct sk_buff *next, *prev;
774 skb->next = skb->prev = NULL;
780 /* XXX: more streamlined implementation */
783 * __skb_dequeue_tail - remove from the tail of the queue
784 * @list: list to dequeue from
786 * Remove the tail of the list. This function does not take any locks
787 * so must be used with appropriate locks held only. The tail item is
788 * returned or %NULL if the list is empty.
790 extern struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
791 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
793 struct sk_buff *skb = skb_peek_tail(list);
795 __skb_unlink(skb, list);
800 static inline int skb_is_nonlinear(const struct sk_buff *skb)
802 return skb->data_len;
805 static inline unsigned int skb_headlen(const struct sk_buff *skb)
807 return skb->len - skb->data_len;
810 static inline int skb_pagelen(const struct sk_buff *skb)
814 for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
815 len += skb_shinfo(skb)->frags[i].size;
816 return len + skb_headlen(skb);
819 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
820 struct page *page, int off, int size)
822 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
825 frag->page_offset = off;
827 skb_shinfo(skb)->nr_frags = i + 1;
830 #define SKB_PAGE_ASSERT(skb) BUG_ON(skb_shinfo(skb)->nr_frags)
831 #define SKB_FRAG_ASSERT(skb) BUG_ON(skb_shinfo(skb)->frag_list)
832 #define SKB_LINEAR_ASSERT(skb) BUG_ON(skb_is_nonlinear(skb))
834 #ifdef NET_SKBUFF_DATA_USES_OFFSET
835 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
837 return skb->head + skb->tail;
840 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
842 skb->tail = skb->data - skb->head;
845 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
847 skb_reset_tail_pointer(skb);
850 #else /* NET_SKBUFF_DATA_USES_OFFSET */
851 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
856 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
858 skb->tail = skb->data;
861 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
863 skb->tail = skb->data + offset;
866 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
869 * Add data to an sk_buff
871 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
873 unsigned char *tmp = skb_tail_pointer(skb);
874 SKB_LINEAR_ASSERT(skb);
881 * skb_put - add data to a buffer
882 * @skb: buffer to use
883 * @len: amount of data to add
885 * This function extends the used data area of the buffer. If this would
886 * exceed the total buffer size the kernel will panic. A pointer to the
887 * first byte of the extra data is returned.
889 static inline unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
891 unsigned char *tmp = skb_tail_pointer(skb);
892 SKB_LINEAR_ASSERT(skb);
895 if (unlikely(skb->tail > skb->end))
896 skb_over_panic(skb, len, current_text_addr());
900 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
908 * skb_push - add data to the start of a buffer
909 * @skb: buffer to use
910 * @len: amount of data to add
912 * This function extends the used data area of the buffer at the buffer
913 * start. If this would exceed the total buffer headroom the kernel will
914 * panic. A pointer to the first byte of the extra data is returned.
916 static inline unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
920 if (unlikely(skb->data<skb->head))
921 skb_under_panic(skb, len, current_text_addr());
925 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
928 BUG_ON(skb->len < skb->data_len);
929 return skb->data += len;
933 * skb_pull - remove data from the start of a buffer
934 * @skb: buffer to use
935 * @len: amount of data to remove
937 * This function removes data from the start of a buffer, returning
938 * the memory to the headroom. A pointer to the next data in the buffer
939 * is returned. Once the data has been pulled future pushes will overwrite
942 static inline unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
944 return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
947 extern unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
949 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
951 if (len > skb_headlen(skb) &&
952 !__pskb_pull_tail(skb, len-skb_headlen(skb)))
955 return skb->data += len;
958 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
960 return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
963 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
965 if (likely(len <= skb_headlen(skb)))
967 if (unlikely(len > skb->len))
969 return __pskb_pull_tail(skb, len-skb_headlen(skb)) != NULL;
973 * skb_headroom - bytes at buffer head
974 * @skb: buffer to check
976 * Return the number of bytes of free space at the head of an &sk_buff.
978 static inline int skb_headroom(const struct sk_buff *skb)
980 return skb->data - skb->head;
984 * skb_tailroom - bytes at buffer end
985 * @skb: buffer to check
987 * Return the number of bytes of free space at the tail of an sk_buff
989 static inline int skb_tailroom(const struct sk_buff *skb)
991 return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
995 * skb_reserve - adjust headroom
996 * @skb: buffer to alter
997 * @len: bytes to move
999 * Increase the headroom of an empty &sk_buff by reducing the tail
1000 * room. This is only allowed for an empty buffer.
1002 static inline void skb_reserve(struct sk_buff *skb, int len)
1008 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1009 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
1011 return skb->head + skb->transport_header;
1014 static inline void skb_reset_transport_header(struct sk_buff *skb)
1016 skb->transport_header = skb->data - skb->head;
1019 static inline void skb_set_transport_header(struct sk_buff *skb,
1022 skb_reset_transport_header(skb);
1023 skb->transport_header += offset;
1026 static inline unsigned char *skb_network_header(const struct sk_buff *skb)
1028 return skb->head + skb->network_header;
1031 static inline void skb_reset_network_header(struct sk_buff *skb)
1033 skb->network_header = skb->data - skb->head;
1036 static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
1038 skb_reset_network_header(skb);
1039 skb->network_header += offset;
1042 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
1044 return skb->head + skb->mac_header;
1047 static inline int skb_mac_header_was_set(const struct sk_buff *skb)
1049 return skb->mac_header != ~0U;
1052 static inline void skb_reset_mac_header(struct sk_buff *skb)
1054 skb->mac_header = skb->data - skb->head;
1057 static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
1059 skb_reset_mac_header(skb);
1060 skb->mac_header += offset;
1063 #else /* NET_SKBUFF_DATA_USES_OFFSET */
1065 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
1067 return skb->transport_header;
1070 static inline void skb_reset_transport_header(struct sk_buff *skb)
1072 skb->transport_header = skb->data;
1075 static inline void skb_set_transport_header(struct sk_buff *skb,
1078 skb->transport_header = skb->data + offset;
1081 static inline unsigned char *skb_network_header(const struct sk_buff *skb)
1083 return skb->network_header;
1086 static inline void skb_reset_network_header(struct sk_buff *skb)
1088 skb->network_header = skb->data;
1091 static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
1093 skb->network_header = skb->data + offset;
1096 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
1098 return skb->mac_header;
1101 static inline int skb_mac_header_was_set(const struct sk_buff *skb)
1103 return skb->mac_header != NULL;
1106 static inline void skb_reset_mac_header(struct sk_buff *skb)
1108 skb->mac_header = skb->data;
1111 static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
1113 skb->mac_header = skb->data + offset;
1115 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
1117 static inline int skb_transport_offset(const struct sk_buff *skb)
1119 return skb_transport_header(skb) - skb->data;
1122 static inline u32 skb_network_header_len(const struct sk_buff *skb)
1124 return skb->transport_header - skb->network_header;
1127 static inline int skb_network_offset(const struct sk_buff *skb)
1129 return skb_network_header(skb) - skb->data;
1133 * CPUs often take a performance hit when accessing unaligned memory
1134 * locations. The actual performance hit varies, it can be small if the
1135 * hardware handles it or large if we have to take an exception and fix it
1138 * Since an ethernet header is 14 bytes network drivers often end up with
1139 * the IP header at an unaligned offset. The IP header can be aligned by
1140 * shifting the start of the packet by 2 bytes. Drivers should do this
1143 * skb_reserve(NET_IP_ALIGN);
1145 * The downside to this alignment of the IP header is that the DMA is now
1146 * unaligned. On some architectures the cost of an unaligned DMA is high
1147 * and this cost outweighs the gains made by aligning the IP header.
1149 * Since this trade off varies between architectures, we allow NET_IP_ALIGN
1152 #ifndef NET_IP_ALIGN
1153 #define NET_IP_ALIGN 2
1157 * The networking layer reserves some headroom in skb data (via
1158 * dev_alloc_skb). This is used to avoid having to reallocate skb data when
1159 * the header has to grow. In the default case, if the header has to grow
1160 * 16 bytes or less we avoid the reallocation.
1162 * Unfortunately this headroom changes the DMA alignment of the resulting
1163 * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
1164 * on some architectures. An architecture can override this value,
1165 * perhaps setting it to a cacheline in size (since that will maintain
1166 * cacheline alignment of the DMA). It must be a power of 2.
1168 * Various parts of the networking layer expect at least 16 bytes of
1169 * headroom, you should not reduce this.
1172 #define NET_SKB_PAD 16
1175 extern int ___pskb_trim(struct sk_buff *skb, unsigned int len);
1177 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
1179 if (unlikely(skb->data_len)) {
1184 skb_set_tail_pointer(skb, len);
1188 * skb_trim - remove end from a buffer
1189 * @skb: buffer to alter
1192 * Cut the length of a buffer down by removing data from the tail. If
1193 * the buffer is already under the length specified it is not modified.
1194 * The skb must be linear.
1196 static inline void skb_trim(struct sk_buff *skb, unsigned int len)
1199 __skb_trim(skb, len);
1203 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
1206 return ___pskb_trim(skb, len);
1207 __skb_trim(skb, len);
1211 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
1213 return (len < skb->len) ? __pskb_trim(skb, len) : 0;
1217 * pskb_trim_unique - remove end from a paged unique (not cloned) buffer
1218 * @skb: buffer to alter
1221 * This is identical to pskb_trim except that the caller knows that
1222 * the skb is not cloned so we should never get an error due to out-
1225 static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
1227 int err = pskb_trim(skb, len);
1232 * skb_orphan - orphan a buffer
1233 * @skb: buffer to orphan
1235 * If a buffer currently has an owner then we call the owner's
1236 * destructor function and make the @skb unowned. The buffer continues
1237 * to exist but is no longer charged to its former owner.
1239 static inline void skb_orphan(struct sk_buff *skb)
1241 if (skb->destructor)
1242 skb->destructor(skb);
1243 skb->destructor = NULL;
1248 * __skb_queue_purge - empty a list
1249 * @list: list to empty
1251 * Delete all buffers on an &sk_buff list. Each buffer is removed from
1252 * the list and one reference dropped. This function does not take the
1253 * list lock and the caller must hold the relevant locks to use it.
1255 extern void skb_queue_purge(struct sk_buff_head *list);
1256 static inline void __skb_queue_purge(struct sk_buff_head *list)
1258 struct sk_buff *skb;
1259 while ((skb = __skb_dequeue(list)) != NULL)
1264 * __dev_alloc_skb - allocate an skbuff for receiving
1265 * @length: length to allocate
1266 * @gfp_mask: get_free_pages mask, passed to alloc_skb
1268 * Allocate a new &sk_buff and assign it a usage count of one. The
1269 * buffer has unspecified headroom built in. Users should allocate
1270 * the headroom they think they need without accounting for the
1271 * built in space. The built in space is used for optimisations.
1273 * %NULL is returned if there is no free memory.
1275 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
1278 struct sk_buff *skb = alloc_skb(length + NET_SKB_PAD, gfp_mask);
1280 skb_reserve(skb, NET_SKB_PAD);
1285 * dev_alloc_skb - allocate an skbuff for receiving
1286 * @length: length to allocate
1288 * Allocate a new &sk_buff and assign it a usage count of one. The
1289 * buffer has unspecified headroom built in. Users should allocate
1290 * the headroom they think they need without accounting for the
1291 * built in space. The built in space is used for optimisations.
1293 * %NULL is returned if there is no free memory. Although this function
1294 * allocates memory it can be called from an interrupt.
1296 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
1298 return __dev_alloc_skb(length, GFP_ATOMIC);
1301 extern struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
1302 unsigned int length, gfp_t gfp_mask);
1305 * netdev_alloc_skb - allocate an skbuff for rx on a specific device
1306 * @dev: network device to receive on
1307 * @length: length to allocate
1309 * Allocate a new &sk_buff and assign it a usage count of one. The
1310 * buffer has unspecified headroom built in. Users should allocate
1311 * the headroom they think they need without accounting for the
1312 * built in space. The built in space is used for optimisations.
1314 * %NULL is returned if there is no free memory. Although this function
1315 * allocates memory it can be called from an interrupt.
1317 static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
1318 unsigned int length)
1320 return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
1324 * skb_cow - copy header of skb when it is required
1325 * @skb: buffer to cow
1326 * @headroom: needed headroom
1328 * If the skb passed lacks sufficient headroom or its data part
1329 * is shared, data is reallocated. If reallocation fails, an error
1330 * is returned and original skb is not changed.
1332 * The result is skb with writable area skb->head...skb->tail
1333 * and at least @headroom of space at head.
1335 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
1337 int delta = (headroom > NET_SKB_PAD ? headroom : NET_SKB_PAD) -
1343 if (delta || skb_cloned(skb))
1344 return pskb_expand_head(skb, (delta + (NET_SKB_PAD-1)) &
1345 ~(NET_SKB_PAD-1), 0, GFP_ATOMIC);
1350 * skb_padto - pad an skbuff up to a minimal size
1351 * @skb: buffer to pad
1352 * @len: minimal length
1354 * Pads up a buffer to ensure the trailing bytes exist and are
1355 * blanked. If the buffer already contains sufficient data it
1356 * is untouched. Otherwise it is extended. Returns zero on
1357 * success. The skb is freed on error.
1360 static inline int skb_padto(struct sk_buff *skb, unsigned int len)
1362 unsigned int size = skb->len;
1363 if (likely(size >= len))
1365 return skb_pad(skb, len-size);
1368 static inline int skb_add_data(struct sk_buff *skb,
1369 char __user *from, int copy)
1371 const int off = skb->len;
1373 if (skb->ip_summed == CHECKSUM_NONE) {
1375 __wsum csum = csum_and_copy_from_user(from, skb_put(skb, copy),
1378 skb->csum = csum_block_add(skb->csum, csum, off);
1381 } else if (!copy_from_user(skb_put(skb, copy), from, copy))
1384 __skb_trim(skb, off);
1388 static inline int skb_can_coalesce(struct sk_buff *skb, int i,
1389 struct page *page, int off)
1392 struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
1394 return page == frag->page &&
1395 off == frag->page_offset + frag->size;
1400 static inline int __skb_linearize(struct sk_buff *skb)
1402 return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
1406 * skb_linearize - convert paged skb to linear one
1407 * @skb: buffer to linarize
1409 * If there is no free memory -ENOMEM is returned, otherwise zero
1410 * is returned and the old skb data released.
1412 static inline int skb_linearize(struct sk_buff *skb)
1414 return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
1418 * skb_linearize_cow - make sure skb is linear and writable
1419 * @skb: buffer to process
1421 * If there is no free memory -ENOMEM is returned, otherwise zero
1422 * is returned and the old skb data released.
1424 static inline int skb_linearize_cow(struct sk_buff *skb)
1426 return skb_is_nonlinear(skb) || skb_cloned(skb) ?
1427 __skb_linearize(skb) : 0;
1431 * skb_postpull_rcsum - update checksum for received skb after pull
1432 * @skb: buffer to update
1433 * @start: start of data before pull
1434 * @len: length of data pulled
1436 * After doing a pull on a received packet, you need to call this to
1437 * update the CHECKSUM_COMPLETE checksum, or set ip_summed to
1438 * CHECKSUM_NONE so that it can be recomputed from scratch.
1441 static inline void skb_postpull_rcsum(struct sk_buff *skb,
1442 const void *start, unsigned int len)
1444 if (skb->ip_summed == CHECKSUM_COMPLETE)
1445 skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
1448 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
1451 * pskb_trim_rcsum - trim received skb and update checksum
1452 * @skb: buffer to trim
1455 * This is exactly the same as pskb_trim except that it ensures the
1456 * checksum of received packets are still valid after the operation.
1459 static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
1461 if (likely(len >= skb->len))
1463 if (skb->ip_summed == CHECKSUM_COMPLETE)
1464 skb->ip_summed = CHECKSUM_NONE;
1465 return __pskb_trim(skb, len);
1468 #define skb_queue_walk(queue, skb) \
1469 for (skb = (queue)->next; \
1470 prefetch(skb->next), (skb != (struct sk_buff *)(queue)); \
1473 #define skb_queue_reverse_walk(queue, skb) \
1474 for (skb = (queue)->prev; \
1475 prefetch(skb->prev), (skb != (struct sk_buff *)(queue)); \
1479 extern struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
1480 int noblock, int *err);
1481 extern unsigned int datagram_poll(struct file *file, struct socket *sock,
1482 struct poll_table_struct *wait);
1483 extern int skb_copy_datagram_iovec(const struct sk_buff *from,
1484 int offset, struct iovec *to,
1486 extern int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,
1489 extern void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
1490 extern void skb_kill_datagram(struct sock *sk, struct sk_buff *skb,
1491 unsigned int flags);
1492 extern __wsum skb_checksum(const struct sk_buff *skb, int offset,
1493 int len, __wsum csum);
1494 extern int skb_copy_bits(const struct sk_buff *skb, int offset,
1496 extern int skb_store_bits(const struct sk_buff *skb, int offset,
1497 void *from, int len);
1498 extern __wsum skb_copy_and_csum_bits(const struct sk_buff *skb,
1499 int offset, u8 *to, int len,
1501 extern void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
1502 extern void skb_split(struct sk_buff *skb,
1503 struct sk_buff *skb1, const u32 len);
1505 extern struct sk_buff *skb_segment(struct sk_buff *skb, int features);
1507 static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
1508 int len, void *buffer)
1510 int hlen = skb_headlen(skb);
1512 if (hlen - offset >= len)
1513 return skb->data + offset;
1515 if (skb_copy_bits(skb, offset, buffer, len) < 0)
1521 static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
1523 const unsigned int len)
1525 memcpy(to, skb->data, len);
1528 static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
1529 const int offset, void *to,
1530 const unsigned int len)
1532 memcpy(to, skb->data + offset, len);
1535 static inline void skb_copy_to_linear_data(struct sk_buff *skb,
1537 const unsigned int len)
1539 memcpy(skb->data, from, len);
1542 static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb,
1545 const unsigned int len)
1547 memcpy(skb->data + offset, from, len);
1550 extern void skb_init(void);
1553 * skb_get_timestamp - get timestamp from a skb
1554 * @skb: skb to get stamp from
1555 * @stamp: pointer to struct timeval to store stamp in
1557 * Timestamps are stored in the skb as offsets to a base timestamp.
1558 * This function converts the offset back to a struct timeval and stores
1561 static inline void skb_get_timestamp(const struct sk_buff *skb, struct timeval *stamp)
1563 *stamp = ktime_to_timeval(skb->tstamp);
1566 static inline void __net_timestamp(struct sk_buff *skb)
1568 skb->tstamp = ktime_get_real();
1572 extern __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
1573 extern __sum16 __skb_checksum_complete(struct sk_buff *skb);
1576 * skb_checksum_complete - Calculate checksum of an entire packet
1577 * @skb: packet to process
1579 * This function calculates the checksum over the entire packet plus
1580 * the value of skb->csum. The latter can be used to supply the
1581 * checksum of a pseudo header as used by TCP/UDP. It returns the
1584 * For protocols that contain complete checksums such as ICMP/TCP/UDP,
1585 * this function can be used to verify that checksum on received
1586 * packets. In that case the function should return zero if the
1587 * checksum is correct. In particular, this function will return zero
1588 * if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
1589 * hardware has already verified the correctness of the checksum.
1591 static inline unsigned int skb_checksum_complete(struct sk_buff *skb)
1593 return skb->ip_summed != CHECKSUM_UNNECESSARY &&
1594 __skb_checksum_complete(skb);
1597 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
1598 extern void nf_conntrack_destroy(struct nf_conntrack *nfct);
1599 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
1601 if (nfct && atomic_dec_and_test(&nfct->use))
1602 nf_conntrack_destroy(nfct);
1604 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
1607 atomic_inc(&nfct->use);
1609 static inline void nf_conntrack_get_reasm(struct sk_buff *skb)
1612 atomic_inc(&skb->users);
1614 static inline void nf_conntrack_put_reasm(struct sk_buff *skb)
1620 #ifdef CONFIG_BRIDGE_NETFILTER
1621 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
1623 if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
1626 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
1629 atomic_inc(&nf_bridge->use);
1631 #endif /* CONFIG_BRIDGE_NETFILTER */
1632 static inline void nf_reset(struct sk_buff *skb)
1634 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
1635 nf_conntrack_put(skb->nfct);
1637 nf_conntrack_put_reasm(skb->nfct_reasm);
1638 skb->nfct_reasm = NULL;
1640 #ifdef CONFIG_BRIDGE_NETFILTER
1641 nf_bridge_put(skb->nf_bridge);
1642 skb->nf_bridge = NULL;
1646 /* Note: This doesn't put any conntrack and bridge info in dst. */
1647 static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src)
1649 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
1650 dst->nfct = src->nfct;
1651 nf_conntrack_get(src->nfct);
1652 dst->nfctinfo = src->nfctinfo;
1653 dst->nfct_reasm = src->nfct_reasm;
1654 nf_conntrack_get_reasm(src->nfct_reasm);
1656 #ifdef CONFIG_BRIDGE_NETFILTER
1657 dst->nf_bridge = src->nf_bridge;
1658 nf_bridge_get(src->nf_bridge);
1662 static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
1664 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
1665 nf_conntrack_put(dst->nfct);
1666 nf_conntrack_put_reasm(dst->nfct_reasm);
1668 #ifdef CONFIG_BRIDGE_NETFILTER
1669 nf_bridge_put(dst->nf_bridge);
1671 __nf_copy(dst, src);
1674 #ifdef CONFIG_NETWORK_SECMARK
1675 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
1677 to->secmark = from->secmark;
1680 static inline void skb_init_secmark(struct sk_buff *skb)
1685 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
1688 static inline void skb_init_secmark(struct sk_buff *skb)
1692 static inline int skb_is_gso(const struct sk_buff *skb)
1694 return skb_shinfo(skb)->gso_size;
1697 static inline void skb_forward_csum(struct sk_buff *skb)
1699 /* Unfortunately we don't support this one. Any brave souls? */
1700 if (skb->ip_summed == CHECKSUM_COMPLETE)
1701 skb->ip_summed = CHECKSUM_NONE;
1704 #endif /* __KERNEL__ */
1705 #endif /* _LINUX_SKBUFF_H */