1 /*
2 * Definitions for the 'struct sk_buff' memory handlers.
3 *
4 * Authors:
5 * Alan Cox, <gw4pts@gw4pts.ampr.org>
6 * Florian La Roche, <rzsfl@rz.uni-sb.de>
7 *
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.
12 */
13
14 #ifndef _LINUX_SKBUFF_H
15 #define _LINUX_SKBUFF_H
16
17 #include <linux/config.h>
18 #include <linux/kernel.h>
19 #include <linux/compiler.h>
20 #include <linux/time.h>
21 #include <linux/cache.h>
22
23 #include <asm/atomic.h>
24 #include <asm/types.h>
25 #include <linux/spinlock.h>
26 #include <linux/mm.h>
27 #include <linux/highmem.h>
28 #include <linux/poll.h>
29 #include <linux/net.h>
30 #include <net/checksum.h>
31
32 #define HAVE_ALLOC_SKB /* For the drivers to know */
33 #define HAVE_ALIGNABLE_SKB /* Ditto 8) */
34 #define SLAB_SKB /* Slabified skbuffs */
35
36 #define CHECKSUM_NONE 0
37 #define CHECKSUM_HW 1
38 #define CHECKSUM_UNNECESSARY 2
39
40 #define SKB_DATA_ALIGN(X) (((X) + (SMP_CACHE_BYTES - 1)) & \
41 ~(SMP_CACHE_BYTES - 1))
42 #define SKB_MAX_ORDER(X, ORDER) (((PAGE_SIZE << (ORDER)) - (X) - \
43 sizeof(struct skb_shared_info)) & \
44 ~(SMP_CACHE_BYTES - 1))
45 #define SKB_MAX_HEAD(X) (SKB_MAX_ORDER((X), 0))
46 #define SKB_MAX_ALLOC (SKB_MAX_ORDER(0, 2))
47
48 /* A. Checksumming of received packets by device.
49 *
50 * NONE: device failed to checksum this packet.
51 * skb->csum is undefined.
52 *
53 * UNNECESSARY: device parsed packet and wouldbe verified checksum.
54 * skb->csum is undefined.
55 * It is bad option, but, unfortunately, many of vendors do this.
56 * Apparently with secret goal to sell you new device, when you
57 * will add new protocol to your host. F.e. IPv6. 8)
58 *
59 * HW: the most generic way. Device supplied checksum of _all_
60 * the packet as seen by netif_rx in skb->csum.
61 * NOTE: Even if device supports only some protocols, but
62 * is able to produce some skb->csum, it MUST use HW,
63 * not UNNECESSARY.
64 *
65 * B. Checksumming on output.
66 *
67 * NONE: skb is checksummed by protocol or csum is not required.
68 *
69 * HW: device is required to csum packet as seen by hard_start_xmit
70 * from skb->h.raw to the end and to record the checksum
71 * at skb->h.raw+skb->csum.
72 *
73 * Device must show its capabilities in dev->features, set
74 * at device setup time.
75 * NETIF_F_HW_CSUM - it is clever device, it is able to checksum
76 * everything.
77 * NETIF_F_NO_CSUM - loopback or reliable single hop media.
78 * NETIF_F_IP_CSUM - device is dumb. It is able to csum only
79 * TCP/UDP over IPv4. Sigh. Vendors like this
80 * way by an unknown reason. Though, see comment above
81 * about CHECKSUM_UNNECESSARY. 8)
82 *
83 * Any questions? No questions, good. --ANK
84 */
85
86 #ifdef __i386__
87 #define NET_CALLER(arg) (*(((void **)&arg) - 1))
88 #else
89 #define NET_CALLER(arg) __builtin_return_address(0)
90 #endif
91
92 struct net_device;
93
94 #ifdef CONFIG_NETFILTER
95 struct nf_conntrack {
96 atomic_t use;
97 void (*destroy)(struct nf_conntrack *);
98 };
99
100 #ifdef CONFIG_BRIDGE_NETFILTER
101 struct nf_bridge_info {
102 atomic_t use;
103 struct net_device *physindev;
104 struct net_device *physoutdev;
105 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
106 struct net_device *netoutdev;
107 #endif
108 unsigned int mask;
109 unsigned long data[32 / sizeof(unsigned long)];
110 };
111 #endif
112
113 #endif
114
115 struct sk_buff_head {
116 /* These two members must be first. */
117 struct sk_buff *next;
118 struct sk_buff *prev;
119
120 __u32 qlen;
121 spinlock_t lock;
122 };
123
124 struct sk_buff;
125
126 /* To allow 64K frame to be packed as single skb without frag_list */
127 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 2)
128
129 typedef struct skb_frag_struct skb_frag_t;
130
131 struct skb_frag_struct {
132 struct page *page;
133 __u16 page_offset;
134 __u16 size;
135 };
136
137 /* This data is invariant across clones and lives at
138 * the end of the header data, ie. at skb->end.
139 */
140 struct skb_shared_info {
141 atomic_t dataref;
142 unsigned int nr_frags;
143 unsigned short tso_size;
144 unsigned short tso_segs;
145 struct sk_buff *frag_list;
146 skb_frag_t frags[MAX_SKB_FRAGS];
147 };
148
149 /**
150 * struct sk_buff - socket buffer
151 * @next: Next buffer in list
152 * @prev: Previous buffer in list
153 * @list: List we are on
154 * @sk: Socket we are owned by
155 * @stamp: Time we arrived
156 * @dev: Device we arrived on/are leaving by
157 * @input_dev: Device we arrived on
158 * @real_dev: The real device we are using
159 * @h: Transport layer header
160 * @nh: Network layer header
161 * @mac: Link layer header
162 * @dst: FIXME: Describe this field
163 * @cb: Control buffer. Free for use by every layer. Put private vars here
164 * @len: Length of actual data
165 * @data_len: Data length
166 * @mac_len: Length of link layer header
167 * @csum: Checksum
168 * @__unused: Dead field, may be reused
169 * @cloned: Head may be cloned (check refcnt to be sure)
170 * @pkt_type: Packet class
171 * @ip_summed: Driver fed us an IP checksum
172 * @priority: Packet queueing priority
173 * @users: User count - see {datagram,tcp}.c
174 * @protocol: Packet protocol from driver
175 * @security: Security level of packet
176 * @truesize: Buffer size
177 * @head: Head of buffer
178 * @data: Data head pointer
179 * @tail: Tail pointer
180 * @end: End pointer
181 * @destructor: Destruct function
182 * @nfmark: Can be used for communication between hooks
183 * @nfcache: Cache info
184 * @nfct: Associated connection, if any
185 * @nfctinfo: Relationship of this skb to the connection
186 * @nf_debug: Netfilter debugging
187 * @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
188 * @private: Data which is private to the HIPPI implementation
189 * @tc_index: Traffic control index
190 */
191
192 struct sk_buff {
193 /* These two members must be first. */
194 struct sk_buff *next;
195 struct sk_buff *prev;
196
197 struct sk_buff_head *list;
198 struct sock *sk;
199 struct timeval stamp;
200 struct net_device *dev;
201 struct net_device *input_dev;
202 struct net_device *real_dev;
203
204 union {
205 struct tcphdr *th;
206 struct udphdr *uh;
207 struct icmphdr *icmph;
208 struct igmphdr *igmph;
209 struct iphdr *ipiph;
210 struct ipv6hdr *ipv6h;
211 unsigned char *raw;
212 } h;
213
214 union {
215 struct iphdr *iph;
216 struct ipv6hdr *ipv6h;
217 struct arphdr *arph;
218 unsigned char *raw;
219 } nh;
220
221 union {
222 unsigned char *raw;
223 } mac;
224
225 struct dst_entry *dst;
226 struct sec_path *sp;
227
228 /*
229 * This is the control buffer. It is free to use for every
230 * layer. Please put your private variables there. If you
231 * want to keep them across layers you have to do a skb_clone()
232 * first. This is owned by whoever has the skb queued ATM.
233 */
234 char cb[40];
235
236 unsigned int len,
237 data_len,
238 mac_len,
239 csum;
240 unsigned char local_df,
241 cloned,
242 pkt_type,
243 ip_summed;
244 __u32 priority;
245 unsigned short protocol,
246 security;
247
248 void (*destructor)(struct sk_buff *skb);
249 #ifdef CONFIG_NETFILTER
250 unsigned long nfmark;
251 __u32 nfcache;
252 __u32 nfctinfo;
253 struct nf_conntrack *nfct;
254 #ifdef CONFIG_NETFILTER_DEBUG
255 unsigned int nf_debug;
256 #endif
257 #ifdef CONFIG_BRIDGE_NETFILTER
258 struct nf_bridge_info *nf_bridge;
259 #endif
260 #endif /* CONFIG_NETFILTER */
261 #if defined(CONFIG_HIPPI)
262 union {
263 __u32 ifield;
264 } private;
265 #endif
266 #ifdef CONFIG_NET_SCHED
267 __u32 tc_index; /* traffic control index */
268 #ifdef CONFIG_NET_CLS_ACT
269 __u32 tc_verd; /* traffic control verdict */
270 __u32 tc_classid; /* traffic control classid */
271 #endif
272
273 #endif
274
275
276 /* These elements must be at the end, see alloc_skb() for details. */
277 unsigned int truesize;
278 atomic_t users;
279 unsigned char *head,
280 *data,
281 *tail,
282 *end;
283 };
284
285 #ifdef __KERNEL__
286 /*
287 * Handling routines are only of interest to the kernel
288 */
289 #include <linux/slab.h>
290
291 #include <asm/system.h>
292
293 extern void __kfree_skb(struct sk_buff *skb);
294 extern struct sk_buff *alloc_skb(unsigned int size, int priority);
295 extern struct sk_buff *alloc_skb_from_cache(kmem_cache_t *cp,
296 unsigned int size, int priority);
297 extern void kfree_skbmem(struct sk_buff *skb);
298 extern struct sk_buff *skb_clone(struct sk_buff *skb, int priority);
299 extern struct sk_buff *skb_copy(const struct sk_buff *skb, int priority);
300 extern struct sk_buff *pskb_copy(struct sk_buff *skb, int gfp_mask);
301 extern int pskb_expand_head(struct sk_buff *skb,
302 int nhead, int ntail, int gfp_mask);
303 extern struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
304 unsigned int headroom);
305 extern struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
306 int newheadroom, int newtailroom,
307 int priority);
308 extern struct sk_buff * skb_pad(struct sk_buff *skb, int pad);
309 #define dev_kfree_skb(a) kfree_skb(a)
310 extern void skb_over_panic(struct sk_buff *skb, int len,
311 void *here);
312 extern void skb_under_panic(struct sk_buff *skb, int len,
313 void *here);
314
315 /* Internal */
316 #define skb_shinfo(SKB) ((struct skb_shared_info *)((SKB)->end))
317
318 /**
319 * skb_queue_empty - check if a queue is empty
320 * @list: queue head
321 *
322 * Returns true if the queue is empty, false otherwise.
323 */
324 static inline int skb_queue_empty(const struct sk_buff_head *list)
325 {
326 return list->next == (struct sk_buff *)list;
327 }
328
329 /**
330 * skb_get - reference buffer
331 * @skb: buffer to reference
332 *
333 * Makes another reference to a socket buffer and returns a pointer
334 * to the buffer.
335 */
336 static inline struct sk_buff *skb_get(struct sk_buff *skb)
337 {
338 atomic_inc(&skb->users);
339 return skb;
340 }
341
342 /*
343 * If users == 1, we are the only owner and are can avoid redundant
344 * atomic change.
345 */
346
347 /**
348 * kfree_skb - free an sk_buff
349 * @skb: buffer to free
350 *
351 * Drop a reference to the buffer and free it if the usage count has
352 * hit zero.
353 */
354 static inline void kfree_skb(struct sk_buff *skb)
355 {
356 if (likely(atomic_read(&skb->users) == 1))
357 smp_rmb();
358 else if (likely(!atomic_dec_and_test(&skb->users)))
359 return;
360 __kfree_skb(skb);
361 }
362
363 /**
364 * skb_cloned - is the buffer a clone
365 * @skb: buffer to check
366 *
367 * Returns true if the buffer was generated with skb_clone() and is
368 * one of multiple shared copies of the buffer. Cloned buffers are
369 * shared data so must not be written to under normal circumstances.
370 */
371 static inline int skb_cloned(const struct sk_buff *skb)
372 {
373 return skb->cloned && atomic_read(&skb_shinfo(skb)->dataref) != 1;
374 }
375
376 /**
377 * skb_shared - is the buffer shared
378 * @skb: buffer to check
379 *
380 * Returns true if more than one person has a reference to this
381 * buffer.
382 */
383 static inline int skb_shared(const struct sk_buff *skb)
384 {
385 return atomic_read(&skb->users) != 1;
386 }
387
388 /**
389 * skb_share_check - check if buffer is shared and if so clone it
390 * @skb: buffer to check
391 * @pri: priority for memory allocation
392 *
393 * If the buffer is shared the buffer is cloned and the old copy
394 * drops a reference. A new clone with a single reference is returned.
395 * If the buffer is not shared the original buffer is returned. When
396 * being called from interrupt status or with spinlocks held pri must
397 * be GFP_ATOMIC.
398 *
399 * NULL is returned on a memory allocation failure.
400 */
401 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, int pri)
402 {
403 might_sleep_if(pri & __GFP_WAIT);
404 if (skb_shared(skb)) {
405 struct sk_buff *nskb = skb_clone(skb, pri);
406 kfree_skb(skb);
407 skb = nskb;
408 }
409 return skb;
410 }
411
412 /*
413 * Copy shared buffers into a new sk_buff. We effectively do COW on
414 * packets to handle cases where we have a local reader and forward
415 * and a couple of other messy ones. The normal one is tcpdumping
416 * a packet thats being forwarded.
417 */
418
419 /**
420 * skb_unshare - make a copy of a shared buffer
421 * @skb: buffer to check
422 * @pri: priority for memory allocation
423 *
424 * If the socket buffer is a clone then this function creates a new
425 * copy of the data, drops a reference count on the old copy and returns
426 * the new copy with the reference count at 1. If the buffer is not a clone
427 * the original buffer is returned. When called with a spinlock held or
428 * from interrupt state @pri must be %GFP_ATOMIC
429 *
430 * %NULL is returned on a memory allocation failure.
431 */
432 static inline struct sk_buff *skb_unshare(struct sk_buff *skb, int pri)
433 {
434 might_sleep_if(pri & __GFP_WAIT);
435 if (skb_cloned(skb)) {
436 struct sk_buff *nskb = skb_copy(skb, pri);
437 kfree_skb(skb); /* Free our shared copy */
438 skb = nskb;
439 }
440 return skb;
441 }
442
443 /**
444 * skb_peek
445 * @list_: list to peek at
446 *
447 * Peek an &sk_buff. Unlike most other operations you _MUST_
448 * be careful with this one. A peek leaves the buffer on the
449 * list and someone else may run off with it. You must hold
450 * the appropriate locks or have a private queue to do this.
451 *
452 * Returns %NULL for an empty list or a pointer to the head element.
453 * The reference count is not incremented and the reference is therefore
454 * volatile. Use with caution.
455 */
456 static inline struct sk_buff *skb_peek(struct sk_buff_head *list_)
457 {
458 struct sk_buff *list = ((struct sk_buff *)list_)->next;
459 if (list == (struct sk_buff *)list_)
460 list = NULL;
461 return list;
462 }
463
464 /**
465 * skb_peek_tail
466 * @list_: list to peek at
467 *
468 * Peek an &sk_buff. Unlike most other operations you _MUST_
469 * be careful with this one. A peek leaves the buffer on the
470 * list and someone else may run off with it. You must hold
471 * the appropriate locks or have a private queue to do this.
472 *
473 * Returns %NULL for an empty list or a pointer to the tail element.
474 * The reference count is not incremented and the reference is therefore
475 * volatile. Use with caution.
476 */
477 static inline struct sk_buff *skb_peek_tail(struct sk_buff_head *list_)
478 {
479 struct sk_buff *list = ((struct sk_buff *)list_)->prev;
480 if (list == (struct sk_buff *)list_)
481 list = NULL;
482 return list;
483 }
484
485 /**
486 * skb_queue_len - get queue length
487 * @list_: list to measure
488 *
489 * Return the length of an &sk_buff queue.
490 */
491 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
492 {
493 return list_->qlen;
494 }
495
496 static inline void skb_queue_head_init(struct sk_buff_head *list)
497 {
498 spin_lock_init(&list->lock);
499 list->prev = list->next = (struct sk_buff *)list;
500 list->qlen = 0;
501 }
502
503 /*
504 * Insert an sk_buff at the start of a list.
505 *
506 * The "__skb_xxxx()" functions are the non-atomic ones that
507 * can only be called with interrupts disabled.
508 */
509
510 /**
511 * __skb_queue_head - queue a buffer at the list head
512 * @list: list to use
513 * @newsk: buffer to queue
514 *
515 * Queue a buffer at the start of a list. This function takes no locks
516 * and you must therefore hold required locks before calling it.
517 *
518 * A buffer cannot be placed on two lists at the same time.
519 */
520 extern void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
521 static inline void __skb_queue_head(struct sk_buff_head *list,
522 struct sk_buff *newsk)
523 {
524 struct sk_buff *prev, *next;
525
526 newsk->list = list;
527 list->qlen++;
528 prev = (struct sk_buff *)list;
529 next = prev->next;
530 newsk->next = next;
531 newsk->prev = prev;
532 next->prev = prev->next = newsk;
533 }
534
535 /**
536 * __skb_queue_tail - queue a buffer at the list tail
537 * @list: list to use
538 * @newsk: buffer to queue
539 *
540 * Queue a buffer at the end of a list. This function takes no locks
541 * and you must therefore hold required locks before calling it.
542 *
543 * A buffer cannot be placed on two lists at the same time.
544 */
545 extern void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
546 static inline void __skb_queue_tail(struct sk_buff_head *list,
547 struct sk_buff *newsk)
548 {
549 struct sk_buff *prev, *next;
550
551 newsk->list = list;
552 list->qlen++;
553 next = (struct sk_buff *)list;
554 prev = next->prev;
555 newsk->next = next;
556 newsk->prev = prev;
557 next->prev = prev->next = newsk;
558 }
559
560
561 /**
562 * __skb_dequeue - remove from the head of the queue
563 * @list: list to dequeue from
564 *
565 * Remove the head of the list. This function does not take any locks
566 * so must be used with appropriate locks held only. The head item is
567 * returned or %NULL if the list is empty.
568 */
569 extern struct sk_buff *skb_dequeue(struct sk_buff_head *list);
570 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
571 {
572 struct sk_buff *next, *prev, *result;
573
574 prev = (struct sk_buff *) list;
575 next = prev->next;
576 result = NULL;
577 if (next != prev) {
578 result = next;
579 next = next->next;
580 list->qlen--;
581 next->prev = prev;
582 prev->next = next;
583 result->next = result->prev = NULL;
584 result->list = NULL;
585 }
586 return result;
587 }
588
589
590 /*
591 * Insert a packet on a list.
592 */
593 extern void skb_insert(struct sk_buff *old, struct sk_buff *newsk);
594 static inline void __skb_insert(struct sk_buff *newsk,
595 struct sk_buff *prev, struct sk_buff *next,
596 struct sk_buff_head *list)
597 {
598 newsk->next = next;
599 newsk->prev = prev;
600 next->prev = prev->next = newsk;
601 newsk->list = list;
602 list->qlen++;
603 }
604
605 /*
606 * Place a packet after a given packet in a list.
607 */
608 extern void skb_append(struct sk_buff *old, struct sk_buff *newsk);
609 static inline void __skb_append(struct sk_buff *old, struct sk_buff *newsk)
610 {
611 __skb_insert(newsk, old, old->next, old->list);
612 }
613
614 /*
615 * remove sk_buff from list. _Must_ be called atomically, and with
616 * the list known..
617 */
618 extern void skb_unlink(struct sk_buff *skb);
619 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
620 {
621 struct sk_buff *next, *prev;
622
623 list->qlen--;
624 next = skb->next;
625 prev = skb->prev;
626 skb->next = skb->prev = NULL;
627 skb->list = NULL;
628 next->prev = prev;
629 prev->next = next;
630 }
631
632
633 /* XXX: more streamlined implementation */
634
635 /**
636 * __skb_dequeue_tail - remove from the tail of the queue
637 * @list: list to dequeue from
638 *
639 * Remove the tail of the list. This function does not take any locks
640 * so must be used with appropriate locks held only. The tail item is
641 * returned or %NULL if the list is empty.
642 */
643 extern struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
644 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
645 {
646 struct sk_buff *skb = skb_peek_tail(list);
647 if (skb)
648 __skb_unlink(skb, list);
649 return skb;
650 }
651
652
653 static inline int skb_is_nonlinear(const struct sk_buff *skb)
654 {
655 return skb->data_len;
656 }
657
658 static inline unsigned int skb_headlen(const struct sk_buff *skb)
659 {
660 return skb->len - skb->data_len;
661 }
662
663 static inline int skb_pagelen(const struct sk_buff *skb)
664 {
665 int i, len = 0;
666
667 for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
668 len += skb_shinfo(skb)->frags[i].size;
669 return len + skb_headlen(skb);
670 }
671
672 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
673 struct page *page, int off, int size)
674 {
675 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
676
677 frag->page = page;
678 frag->page_offset = off;
679 frag->size = size;
680 skb_shinfo(skb)->nr_frags = i + 1;
681 }
682
683 #define SKB_PAGE_ASSERT(skb) BUG_ON(skb_shinfo(skb)->nr_frags)
684 #define SKB_FRAG_ASSERT(skb) BUG_ON(skb_shinfo(skb)->frag_list)
685 #define SKB_LINEAR_ASSERT(skb) BUG_ON(skb_is_nonlinear(skb))
686
687 /*
688 * Add data to an sk_buff
689 */
690 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
691 {
692 unsigned char *tmp = skb->tail;
693 SKB_LINEAR_ASSERT(skb);
694 skb->tail += len;
695 skb->len += len;
696 return tmp;
697 }
698
699 /**
700 * skb_put - add data to a buffer
701 * @skb: buffer to use
702 * @len: amount of data to add
703 *
704 * This function extends the used data area of the buffer. If this would
705 * exceed the total buffer size the kernel will panic. A pointer to the
706 * first byte of the extra data is returned.
707 */
708 static inline unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
709 {
710 unsigned char *tmp = skb->tail;
711 SKB_LINEAR_ASSERT(skb);
712 skb->tail += len;
713 skb->len += len;
714 if (unlikely(skb->tail>skb->end))
715 skb_over_panic(skb, len, current_text_addr());
716 return tmp;
717 }
718
719 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
720 {
721 skb->data -= len;
722 skb->len += len;
723 return skb->data;
724 }
725
726 /**
727 * skb_push - add data to the start of a buffer
728 * @skb: buffer to use
729 * @len: amount of data to add
730 *
731 * This function extends the used data area of the buffer at the buffer
732 * start. If this would exceed the total buffer headroom the kernel will
733 * panic. A pointer to the first byte of the extra data is returned.
734 */
735 static inline unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
736 {
737 skb->data -= len;
738 skb->len += len;
739 if (unlikely(skb->data<skb->head))
740 skb_under_panic(skb, len, current_text_addr());
741 return skb->data;
742 }
743
744 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
745 {
746 skb->len -= len;
747 BUG_ON(skb->len < skb->data_len);
748 return skb->data += len;
749 }
750
751 /**
752 * skb_pull - remove data from the start of a buffer
753 * @skb: buffer to use
754 * @len: amount of data to remove
755 *
756 * This function removes data from the start of a buffer, returning
757 * the memory to the headroom. A pointer to the next data in the buffer
758 * is returned. Once the data has been pulled future pushes will overwrite
759 * the old data.
760 */
761 static inline unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
762 {
763 return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
764 }
765
766 extern unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
767
768 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
769 {
770 if (len > skb_headlen(skb) &&
771 !__pskb_pull_tail(skb, len-skb_headlen(skb)))
772 return NULL;
773 skb->len -= len;
774 return skb->data += len;
775 }
776
777 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
778 {
779 return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
780 }
781
782 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
783 {
784 if (likely(len <= skb_headlen(skb)))
785 return 1;
786 if (unlikely(len > skb->len))
787 return 0;
788 return __pskb_pull_tail(skb, len-skb_headlen(skb)) != NULL;
789 }
790
791 /**
792 * skb_headroom - bytes at buffer head
793 * @skb: buffer to check
794 *
795 * Return the number of bytes of free space at the head of an &sk_buff.
796 */
797 static inline int skb_headroom(const struct sk_buff *skb)
798 {
799 return skb->data - skb->head;
800 }
801
802 /**
803 * skb_tailroom - bytes at buffer end
804 * @skb: buffer to check
805 *
806 * Return the number of bytes of free space at the tail of an sk_buff
807 */
808 static inline int skb_tailroom(const struct sk_buff *skb)
809 {
810 return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
811 }
812
813 /**
814 * skb_reserve - adjust headroom
815 * @skb: buffer to alter
816 * @len: bytes to move
817 *
818 * Increase the headroom of an empty &sk_buff by reducing the tail
819 * room. This is only allowed for an empty buffer.
820 */
821 static inline void skb_reserve(struct sk_buff *skb, unsigned int len)
822 {
823 skb->data += len;
824 skb->tail += len;
825 }
826
827 /*
828 * CPUs often take a performance hit when accessing unaligned memory
829 * locations. The actual performance hit varies, it can be small if the
830 * hardware handles it or large if we have to take an exception and fix it
831 * in software.
832 *
833 * Since an ethernet header is 14 bytes network drivers often end up with
834 * the IP header at an unaligned offset. The IP header can be aligned by
835 * shifting the start of the packet by 2 bytes. Drivers should do this
836 * with:
837 *
838 * skb_reserve(NET_IP_ALIGN);
839 *
840 * The downside to this alignment of the IP header is that the DMA is now
841 * unaligned. On some architectures the cost of an unaligned DMA is high
842 * and this cost outweighs the gains made by aligning the IP header.
843 *
844 * Since this trade off varies between architectures, we allow NET_IP_ALIGN
845 * to be overridden.
846 */
847 #ifndef NET_IP_ALIGN
848 #define NET_IP_ALIGN 2
849 #endif
850
851 extern int ___pskb_trim(struct sk_buff *skb, unsigned int len, int realloc);
852
853 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
854 {
855 if (!skb->data_len) {
856 skb->len = len;
857 skb->tail = skb->data + len;
858 } else
859 ___pskb_trim(skb, len, 0);
860 }
861
862 /**
863 * skb_trim - remove end from a buffer
864 * @skb: buffer to alter
865 * @len: new length
866 *
867 * Cut the length of a buffer down by removing data from the tail. If
868 * the buffer is already under the length specified it is not modified.
869 */
870 static inline void skb_trim(struct sk_buff *skb, unsigned int len)
871 {
872 if (skb->len > len)
873 __skb_trim(skb, len);
874 }
875
876
877 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
878 {
879 if (!skb->data_len) {
880 skb->len = len;
881 skb->tail = skb->data+len;
882 return 0;
883 }
884 return ___pskb_trim(skb, len, 1);
885 }
886
887 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
888 {
889 return (len < skb->len) ? __pskb_trim(skb, len) : 0;
890 }
891
892 /**
893 * skb_orphan - orphan a buffer
894 * @skb: buffer to orphan
895 *
896 * If a buffer currently has an owner then we call the owner's
897 * destructor function and make the @skb unowned. The buffer continues
898 * to exist but is no longer charged to its former owner.
899 */
900 static inline void skb_orphan(struct sk_buff *skb)
901 {
902 if (skb->destructor)
903 skb->destructor(skb);
904 skb->destructor = NULL;
905 skb->sk = NULL;
906 }
907
908 /**
909 * __skb_queue_purge - empty a list
910 * @list: list to empty
911 *
912 * Delete all buffers on an &sk_buff list. Each buffer is removed from
913 * the list and one reference dropped. This function does not take the
914 * list lock and the caller must hold the relevant locks to use it.
915 */
916 extern void skb_queue_purge(struct sk_buff_head *list);
917 static inline void __skb_queue_purge(struct sk_buff_head *list)
918 {
919 struct sk_buff *skb;
920 while ((skb = __skb_dequeue(list)) != NULL)
921 kfree_skb(skb);
922 }
923
924 /**
925 * __dev_alloc_skb - allocate an skbuff for sending
926 * @length: length to allocate
927 * @gfp_mask: get_free_pages mask, passed to alloc_skb
928 *
929 * Allocate a new &sk_buff and assign it a usage count of one. The
930 * buffer has unspecified headroom built in. Users should allocate
931 * the headroom they think they need without accounting for the
932 * built in space. The built in space is used for optimisations.
933 *
934 * %NULL is returned in there is no free memory.
935 */
936 #ifndef CONFIG_HAVE_ARCH_DEV_ALLOC_SKB
937 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
938 int gfp_mask)
939 {
940 struct sk_buff *skb = alloc_skb(length + 16, gfp_mask);
941 if (likely(skb))
942 skb_reserve(skb, 16);
943 return skb;
944 }
945 #else
946 extern struct sk_buff *__dev_alloc_skb(unsigned int length, int gfp_mask);
947 #endif
948
949 /**
950 * dev_alloc_skb - allocate an skbuff for sending
951 * @length: length to allocate
952 *
953 * Allocate a new &sk_buff and assign it a usage count of one. The
954 * buffer has unspecified headroom built in. Users should allocate
955 * the headroom they think they need without accounting for the
956 * built in space. The built in space is used for optimisations.
957 *
958 * %NULL is returned in there is no free memory. Although this function
959 * allocates memory it can be called from an interrupt.
960 */
961 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
962 {
963 return __dev_alloc_skb(length, GFP_ATOMIC);
964 }
965
966 /**
967 * skb_cow - copy header of skb when it is required
968 * @skb: buffer to cow
969 * @headroom: needed headroom
970 *
971 * If the skb passed lacks sufficient headroom or its data part
972 * is shared, data is reallocated. If reallocation fails, an error
973 * is returned and original skb is not changed.
974 *
975 * The result is skb with writable area skb->head...skb->tail
976 * and at least @headroom of space at head.
977 */
978 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
979 {
980 int delta = (headroom > 16 ? headroom : 16) - skb_headroom(skb);
981
982 if (delta < 0)
983 delta = 0;
984
985 if (delta || skb_cloned(skb))
986 return pskb_expand_head(skb, (delta + 15) & ~15, 0, GFP_ATOMIC);
987 return 0;
988 }
989
990 /**
991 * skb_padto - pad an skbuff up to a minimal size
992 * @skb: buffer to pad
993 * @len: minimal length
994 *
995 * Pads up a buffer to ensure the trailing bytes exist and are
996 * blanked. If the buffer already contains sufficient data it
997 * is untouched. Returns the buffer, which may be a replacement
998 * for the original, or NULL for out of memory - in which case
999 * the original buffer is still freed.
1000 */
1001
1002 static inline struct sk_buff *skb_padto(struct sk_buff *skb, unsigned int len)
1003 {
1004 unsigned int size = skb->len;
1005 if (likely(size >= len))
1006 return skb;
1007 return skb_pad(skb, len-size);
1008 }
1009
1010 static inline int skb_add_data(struct sk_buff *skb,
1011 char __user *from, int copy)
1012 {
1013 const int off = skb->len;
1014
1015 if (skb->ip_summed == CHECKSUM_NONE) {
1016 int err = 0;
1017 unsigned int csum = csum_and_copy_from_user(from,
1018 skb_put(skb, copy),
1019 copy, 0, &err);
1020 if (!err) {
1021 skb->csum = csum_block_add(skb->csum, csum, off);
1022 return 0;
1023 }
1024 } else if (!copy_from_user(skb_put(skb, copy), from, copy))
1025 return 0;
1026
1027 __skb_trim(skb, off);
1028 return -EFAULT;
1029 }
1030
1031 static inline int skb_can_coalesce(struct sk_buff *skb, int i,
1032 struct page *page, int off)
1033 {
1034 if (i) {
1035 struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
1036
1037 return page == frag->page &&
1038 off == frag->page_offset + frag->size;
1039 }
1040 return 0;
1041 }
1042
1043 /**
1044 * skb_linearize - convert paged skb to linear one
1045 * @skb: buffer to linarize
1046 * @gfp: allocation mode
1047 *
1048 * If there is no free memory -ENOMEM is returned, otherwise zero
1049 * is returned and the old skb data released.
1050 */
1051 extern int __skb_linearize(struct sk_buff *skb, int gfp);
1052 static inline int skb_linearize(struct sk_buff *skb, int gfp)
1053 {
1054 return __skb_linearize(skb, gfp);
1055 }
1056
1057 static inline void *kmap_skb_frag(const skb_frag_t *frag)
1058 {
1059 #ifdef CONFIG_HIGHMEM
1060 BUG_ON(in_irq());
1061
1062 local_bh_disable();
1063 #endif
1064 return kmap_atomic(frag->page, KM_SKB_DATA_SOFTIRQ);
1065 }
1066
1067 static inline void kunmap_skb_frag(void *vaddr)
1068 {
1069 kunmap_atomic(vaddr, KM_SKB_DATA_SOFTIRQ);
1070 #ifdef CONFIG_HIGHMEM
1071 local_bh_enable();
1072 #endif
1073 }
1074
1075 #define skb_queue_walk(queue, skb) \
1076 for (skb = (queue)->next; \
1077 prefetch(skb->next), (skb != (struct sk_buff *)(queue)); \
1078 skb = skb->next)
1079
1080
1081 extern struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
1082 int noblock, int *err);
1083 extern unsigned int datagram_poll(struct file *file, struct socket *sock,
1084 struct poll_table_struct *wait);
1085 extern int skb_copy_datagram_iovec(const struct sk_buff *from,
1086 int offset, struct iovec *to,
1087 int size);
1088 extern int skb_copy_and_csum_datagram_iovec(const
1089 struct sk_buff *skb,
1090 int hlen,
1091 struct iovec *iov);
1092 extern void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
1093 extern unsigned int skb_checksum(const struct sk_buff *skb, int offset,
1094 int len, unsigned int csum);
1095 extern int skb_copy_bits(const struct sk_buff *skb, int offset,
1096 void *to, int len);
1097 extern unsigned int skb_copy_and_csum_bits(const struct sk_buff *skb,
1098 int offset, u8 *to, int len,
1099 unsigned int csum);
1100 extern void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
1101 extern void skb_split(struct sk_buff *skb,
1102 struct sk_buff *skb1, const u32 len);
1103
1104 static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
1105 int len, void *buffer)
1106 {
1107 int hlen = skb_headlen(skb);
1108
1109 if (offset + len <= hlen)
1110 return skb->data + offset;
1111
1112 if (skb_copy_bits(skb, offset, buffer, len) < 0)
1113 return NULL;
1114
1115 return buffer;
1116 }
1117
1118 extern void skb_init(void);
1119 extern void skb_add_mtu(int mtu);
1120
1121 struct skb_iter {
1122 /* Iteration functions set these */
1123 unsigned char *data;
1124 unsigned int len;
1125
1126 /* Private to iteration */
1127 unsigned int nextfrag;
1128 struct sk_buff *fraglist;
1129 };
1130
1131 /* Keep iterating until skb_iter_next returns false. */
1132 extern void skb_iter_first(const struct sk_buff *skb, struct skb_iter *i);
1133 extern int skb_iter_next(const struct sk_buff *skb, struct skb_iter *i);
1134 /* Call this if aborting loop before !skb_iter_next */
1135 extern void skb_iter_abort(const struct sk_buff *skb, struct skb_iter *i);
1136
1137 #ifdef CONFIG_NETFILTER
1138 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
1139 {
1140 if (nfct && atomic_dec_and_test(&nfct->use))
1141 nfct->destroy(nfct);
1142 }
1143 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
1144 {
1145 if (nfct)
1146 atomic_inc(&nfct->use);
1147 }
1148 static inline void nf_reset(struct sk_buff *skb)
1149 {
1150 nf_conntrack_put(skb->nfct);
1151 skb->nfct = NULL;
1152 #ifdef CONFIG_NETFILTER_DEBUG
1153 skb->nf_debug = 0;
1154 #endif
1155 }
1156 static inline void nf_reset_debug(struct sk_buff *skb)
1157 {
1158 #ifdef CONFIG_NETFILTER_DEBUG
1159 skb->nf_debug = 0;
1160 #endif
1161 }
1162
1163 #ifdef CONFIG_BRIDGE_NETFILTER
1164 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
1165 {
1166 if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
1167 kfree(nf_bridge);
1168 }
1169 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
1170 {
1171 if (nf_bridge)
1172 atomic_inc(&nf_bridge->use);
1173 }
1174 #endif /* CONFIG_BRIDGE_NETFILTER */
1175 #else /* CONFIG_NETFILTER */
1176 static inline void nf_reset(struct sk_buff *skb) {}
1177 #endif /* CONFIG_NETFILTER */
1178
1179 #endif /* __KERNEL__ */
1180 #endif /* _LINUX_SKBUFF_H */
1181
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