2 * Routines having to do with the 'struct sk_buff' memory handlers.
4 * Authors: Alan Cox <alan@lxorguk.ukuu.org.uk>
5 * Florian La Roche <rzsfl@rz.uni-sb.de>
8 * Alan Cox : Fixed the worst of the load
10 * Dave Platt : Interrupt stacking fix.
11 * Richard Kooijman : Timestamp fixes.
12 * Alan Cox : Changed buffer format.
13 * Alan Cox : destructor hook for AF_UNIX etc.
14 * Linus Torvalds : Better skb_clone.
15 * Alan Cox : Added skb_copy.
16 * Alan Cox : Added all the changed routines Linus
17 * only put in the headers
18 * Ray VanTassle : Fixed --skb->lock in free
19 * Alan Cox : skb_copy copy arp field
20 * Andi Kleen : slabified it.
21 * Robert Olsson : Removed skb_head_pool
24 * The __skb_ routines should be called with interrupts
25 * disabled, or you better be *real* sure that the operation is atomic
26 * with respect to whatever list is being frobbed (e.g. via lock_sock()
27 * or via disabling bottom half handlers, etc).
29 * This program is free software; you can redistribute it and/or
30 * modify it under the terms of the GNU General Public License
31 * as published by the Free Software Foundation; either version
32 * 2 of the License, or (at your option) any later version.
36 * The functions in this file will not compile correctly with gcc 2.4.x
39 #include <linux/module.h>
40 #include <linux/types.h>
41 #include <linux/kernel.h>
42 #include <linux/kmemcheck.h>
44 #include <linux/interrupt.h>
46 #include <linux/inet.h>
47 #include <linux/slab.h>
48 #include <linux/netdevice.h>
49 #ifdef CONFIG_NET_CLS_ACT
50 #include <net/pkt_sched.h>
52 #include <linux/string.h>
53 #include <linux/skbuff.h>
54 #include <linux/splice.h>
55 #include <linux/cache.h>
56 #include <linux/rtnetlink.h>
57 #include <linux/init.h>
58 #include <linux/scatterlist.h>
59 #include <linux/errqueue.h>
60 #include <linux/prefetch.h>
62 #include <net/protocol.h>
65 #include <net/checksum.h>
68 #include <asm/uaccess.h>
69 #include <trace/events/skb.h>
70 #include <linux/highmem.h>
72 static struct kmem_cache *skbuff_head_cache __read_mostly;
73 static struct kmem_cache *skbuff_fclone_cache __read_mostly;
75 static void sock_pipe_buf_release(struct pipe_inode_info *pipe,
76 struct pipe_buffer *buf)
81 static void sock_pipe_buf_get(struct pipe_inode_info *pipe,
82 struct pipe_buffer *buf)
87 static int sock_pipe_buf_steal(struct pipe_inode_info *pipe,
88 struct pipe_buffer *buf)
94 /* Pipe buffer operations for a socket. */
95 static const struct pipe_buf_operations sock_pipe_buf_ops = {
97 .map = generic_pipe_buf_map,
98 .unmap = generic_pipe_buf_unmap,
99 .confirm = generic_pipe_buf_confirm,
100 .release = sock_pipe_buf_release,
101 .steal = sock_pipe_buf_steal,
102 .get = sock_pipe_buf_get,
106 * Keep out-of-line to prevent kernel bloat.
107 * __builtin_return_address is not used because it is not always
112 * skb_over_panic - private function
117 * Out of line support code for skb_put(). Not user callable.
119 static void skb_over_panic(struct sk_buff *skb, int sz, void *here)
121 printk(KERN_EMERG "skb_over_panic: text:%p len:%d put:%d head:%p "
122 "data:%p tail:%#lx end:%#lx dev:%s\n",
123 here, skb->len, sz, skb->head, skb->data,
124 (unsigned long)skb->tail, (unsigned long)skb->end,
125 skb->dev ? skb->dev->name : "<NULL>");
130 * skb_under_panic - private function
135 * Out of line support code for skb_push(). Not user callable.
138 static void skb_under_panic(struct sk_buff *skb, int sz, void *here)
140 printk(KERN_EMERG "skb_under_panic: text:%p len:%d put:%d head:%p "
141 "data:%p tail:%#lx end:%#lx dev:%s\n",
142 here, skb->len, sz, skb->head, skb->data,
143 (unsigned long)skb->tail, (unsigned long)skb->end,
144 skb->dev ? skb->dev->name : "<NULL>");
148 /* Allocate a new skbuff. We do this ourselves so we can fill in a few
149 * 'private' fields and also do memory statistics to find all the
155 * __alloc_skb - allocate a network buffer
156 * @size: size to allocate
157 * @gfp_mask: allocation mask
158 * @fclone: allocate from fclone cache instead of head cache
159 * and allocate a cloned (child) skb
160 * @node: numa node to allocate memory on
162 * Allocate a new &sk_buff. The returned buffer has no headroom and a
163 * tail room of size bytes. The object has a reference count of one.
164 * The return is the buffer. On a failure the return is %NULL.
166 * Buffers may only be allocated from interrupts using a @gfp_mask of
169 struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
170 int fclone, int node)
172 struct kmem_cache *cache;
173 struct skb_shared_info *shinfo;
177 cache = fclone ? skbuff_fclone_cache : skbuff_head_cache;
180 skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
185 /* We do our best to align skb_shared_info on a separate cache
186 * line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
187 * aligned memory blocks, unless SLUB/SLAB debug is enabled.
188 * Both skb->head and skb_shared_info are cache line aligned.
190 size = SKB_DATA_ALIGN(size);
191 size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
192 data = kmalloc_node_track_caller(size, gfp_mask, node);
195 /* kmalloc(size) might give us more room than requested.
196 * Put skb_shared_info exactly at the end of allocated zone,
197 * to allow max possible filling before reallocation.
199 size = SKB_WITH_OVERHEAD(ksize(data));
200 prefetchw(data + size);
203 * Only clear those fields we need to clear, not those that we will
204 * actually initialise below. Hence, don't put any more fields after
205 * the tail pointer in struct sk_buff!
207 memset(skb, 0, offsetof(struct sk_buff, tail));
208 /* Account for allocated memory : skb + skb->head */
209 skb->truesize = SKB_TRUESIZE(size);
210 atomic_set(&skb->users, 1);
213 skb_reset_tail_pointer(skb);
214 skb->end = skb->tail + size;
215 #ifdef NET_SKBUFF_DATA_USES_OFFSET
216 skb->mac_header = ~0U;
219 /* make sure we initialize shinfo sequentially */
220 shinfo = skb_shinfo(skb);
221 memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
222 atomic_set(&shinfo->dataref, 1);
223 kmemcheck_annotate_variable(shinfo->destructor_arg);
226 struct sk_buff *child = skb + 1;
227 atomic_t *fclone_ref = (atomic_t *) (child + 1);
229 kmemcheck_annotate_bitfield(child, flags1);
230 kmemcheck_annotate_bitfield(child, flags2);
231 skb->fclone = SKB_FCLONE_ORIG;
232 atomic_set(fclone_ref, 1);
234 child->fclone = SKB_FCLONE_UNAVAILABLE;
239 kmem_cache_free(cache, skb);
243 EXPORT_SYMBOL(__alloc_skb);
246 * build_skb - build a network buffer
247 * @data: data buffer provided by caller
249 * Allocate a new &sk_buff. Caller provides space holding head and
250 * skb_shared_info. @data must have been allocated by kmalloc()
251 * The return is the new skb buffer.
252 * On a failure the return is %NULL, and @data is not freed.
254 * Before IO, driver allocates only data buffer where NIC put incoming frame
255 * Driver should add room at head (NET_SKB_PAD) and
256 * MUST add room at tail (SKB_DATA_ALIGN(skb_shared_info))
257 * After IO, driver calls build_skb(), to allocate sk_buff and populate it
258 * before giving packet to stack.
259 * RX rings only contains data buffers, not full skbs.
261 struct sk_buff *build_skb(void *data)
263 struct skb_shared_info *shinfo;
267 skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
271 size = ksize(data) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
273 memset(skb, 0, offsetof(struct sk_buff, tail));
274 skb->truesize = SKB_TRUESIZE(size);
275 atomic_set(&skb->users, 1);
278 skb_reset_tail_pointer(skb);
279 skb->end = skb->tail + size;
280 #ifdef NET_SKBUFF_DATA_USES_OFFSET
281 skb->mac_header = ~0U;
284 /* make sure we initialize shinfo sequentially */
285 shinfo = skb_shinfo(skb);
286 memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
287 atomic_set(&shinfo->dataref, 1);
288 kmemcheck_annotate_variable(shinfo->destructor_arg);
292 EXPORT_SYMBOL(build_skb);
295 * __netdev_alloc_skb - allocate an skbuff for rx on a specific device
296 * @dev: network device to receive on
297 * @length: length to allocate
298 * @gfp_mask: get_free_pages mask, passed to alloc_skb
300 * Allocate a new &sk_buff and assign it a usage count of one. The
301 * buffer has unspecified headroom built in. Users should allocate
302 * the headroom they think they need without accounting for the
303 * built in space. The built in space is used for optimisations.
305 * %NULL is returned if there is no free memory.
307 struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
308 unsigned int length, gfp_t gfp_mask)
312 skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, NUMA_NO_NODE);
314 skb_reserve(skb, NET_SKB_PAD);
319 EXPORT_SYMBOL(__netdev_alloc_skb);
321 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
322 int size, unsigned int truesize)
324 skb_fill_page_desc(skb, i, page, off, size);
326 skb->data_len += size;
327 skb->truesize += truesize;
329 EXPORT_SYMBOL(skb_add_rx_frag);
332 * dev_alloc_skb - allocate an skbuff for receiving
333 * @length: length to allocate
335 * Allocate a new &sk_buff and assign it a usage count of one. The
336 * buffer has unspecified headroom built in. Users should allocate
337 * the headroom they think they need without accounting for the
338 * built in space. The built in space is used for optimisations.
340 * %NULL is returned if there is no free memory. Although this function
341 * allocates memory it can be called from an interrupt.
343 struct sk_buff *dev_alloc_skb(unsigned int length)
346 * There is more code here than it seems:
347 * __dev_alloc_skb is an inline
349 return __dev_alloc_skb(length, GFP_ATOMIC);
351 EXPORT_SYMBOL(dev_alloc_skb);
353 static void skb_drop_list(struct sk_buff **listp)
355 struct sk_buff *list = *listp;
360 struct sk_buff *this = list;
366 static inline void skb_drop_fraglist(struct sk_buff *skb)
368 skb_drop_list(&skb_shinfo(skb)->frag_list);
371 static void skb_clone_fraglist(struct sk_buff *skb)
373 struct sk_buff *list;
375 skb_walk_frags(skb, list)
379 static void skb_release_data(struct sk_buff *skb)
382 !atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
383 &skb_shinfo(skb)->dataref)) {
384 if (skb_shinfo(skb)->nr_frags) {
386 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
387 skb_frag_unref(skb, i);
391 * If skb buf is from userspace, we need to notify the caller
392 * the lower device DMA has done;
394 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
395 struct ubuf_info *uarg;
397 uarg = skb_shinfo(skb)->destructor_arg;
399 uarg->callback(uarg);
402 if (skb_has_frag_list(skb))
403 skb_drop_fraglist(skb);
410 * Free an skbuff by memory without cleaning the state.
412 static void kfree_skbmem(struct sk_buff *skb)
414 struct sk_buff *other;
415 atomic_t *fclone_ref;
417 switch (skb->fclone) {
418 case SKB_FCLONE_UNAVAILABLE:
419 kmem_cache_free(skbuff_head_cache, skb);
422 case SKB_FCLONE_ORIG:
423 fclone_ref = (atomic_t *) (skb + 2);
424 if (atomic_dec_and_test(fclone_ref))
425 kmem_cache_free(skbuff_fclone_cache, skb);
428 case SKB_FCLONE_CLONE:
429 fclone_ref = (atomic_t *) (skb + 1);
432 /* The clone portion is available for
433 * fast-cloning again.
435 skb->fclone = SKB_FCLONE_UNAVAILABLE;
437 if (atomic_dec_and_test(fclone_ref))
438 kmem_cache_free(skbuff_fclone_cache, other);
443 static void skb_release_head_state(struct sk_buff *skb)
447 secpath_put(skb->sp);
449 if (skb->destructor) {
451 skb->destructor(skb);
453 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
454 nf_conntrack_put(skb->nfct);
456 #ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
457 nf_conntrack_put_reasm(skb->nfct_reasm);
459 #ifdef CONFIG_BRIDGE_NETFILTER
460 nf_bridge_put(skb->nf_bridge);
462 /* XXX: IS this still necessary? - JHS */
463 #ifdef CONFIG_NET_SCHED
465 #ifdef CONFIG_NET_CLS_ACT
471 /* Free everything but the sk_buff shell. */
472 static void skb_release_all(struct sk_buff *skb)
474 skb_release_head_state(skb);
475 skb_release_data(skb);
479 * __kfree_skb - private function
482 * Free an sk_buff. Release anything attached to the buffer.
483 * Clean the state. This is an internal helper function. Users should
484 * always call kfree_skb
487 void __kfree_skb(struct sk_buff *skb)
489 skb_release_all(skb);
492 EXPORT_SYMBOL(__kfree_skb);
495 * kfree_skb - free an sk_buff
496 * @skb: buffer to free
498 * Drop a reference to the buffer and free it if the usage count has
501 void kfree_skb(struct sk_buff *skb)
505 if (likely(atomic_read(&skb->users) == 1))
507 else if (likely(!atomic_dec_and_test(&skb->users)))
509 trace_kfree_skb(skb, __builtin_return_address(0));
512 EXPORT_SYMBOL(kfree_skb);
515 * consume_skb - free an skbuff
516 * @skb: buffer to free
518 * Drop a ref to the buffer and free it if the usage count has hit zero
519 * Functions identically to kfree_skb, but kfree_skb assumes that the frame
520 * is being dropped after a failure and notes that
522 void consume_skb(struct sk_buff *skb)
526 if (likely(atomic_read(&skb->users) == 1))
528 else if (likely(!atomic_dec_and_test(&skb->users)))
530 trace_consume_skb(skb);
533 EXPORT_SYMBOL(consume_skb);
536 * skb_recycle - clean up an skb for reuse
539 * Recycles the skb to be reused as a receive buffer. This
540 * function does any necessary reference count dropping, and
541 * cleans up the skbuff as if it just came from __alloc_skb().
543 void skb_recycle(struct sk_buff *skb)
545 struct skb_shared_info *shinfo;
547 skb_release_head_state(skb);
549 shinfo = skb_shinfo(skb);
550 memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
551 atomic_set(&shinfo->dataref, 1);
553 memset(skb, 0, offsetof(struct sk_buff, tail));
554 skb->data = skb->head + NET_SKB_PAD;
555 skb_reset_tail_pointer(skb);
557 EXPORT_SYMBOL(skb_recycle);
560 * skb_recycle_check - check if skb can be reused for receive
562 * @skb_size: minimum receive buffer size
564 * Checks that the skb passed in is not shared or cloned, and
565 * that it is linear and its head portion at least as large as
566 * skb_size so that it can be recycled as a receive buffer.
567 * If these conditions are met, this function does any necessary
568 * reference count dropping and cleans up the skbuff as if it
569 * just came from __alloc_skb().
571 bool skb_recycle_check(struct sk_buff *skb, int skb_size)
573 if (!skb_is_recycleable(skb, skb_size))
580 EXPORT_SYMBOL(skb_recycle_check);
582 static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
584 new->tstamp = old->tstamp;
586 new->transport_header = old->transport_header;
587 new->network_header = old->network_header;
588 new->mac_header = old->mac_header;
589 skb_dst_copy(new, old);
590 new->rxhash = old->rxhash;
591 new->ooo_okay = old->ooo_okay;
592 new->l4_rxhash = old->l4_rxhash;
593 new->no_fcs = old->no_fcs;
595 new->sp = secpath_get(old->sp);
597 memcpy(new->cb, old->cb, sizeof(old->cb));
598 new->csum = old->csum;
599 new->local_df = old->local_df;
600 new->pkt_type = old->pkt_type;
601 new->ip_summed = old->ip_summed;
602 skb_copy_queue_mapping(new, old);
603 new->priority = old->priority;
604 #if IS_ENABLED(CONFIG_IP_VS)
605 new->ipvs_property = old->ipvs_property;
607 new->protocol = old->protocol;
608 new->mark = old->mark;
609 new->skb_iif = old->skb_iif;
611 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE)
612 new->nf_trace = old->nf_trace;
614 #ifdef CONFIG_NET_SCHED
615 new->tc_index = old->tc_index;
616 #ifdef CONFIG_NET_CLS_ACT
617 new->tc_verd = old->tc_verd;
620 new->vlan_tci = old->vlan_tci;
622 skb_copy_secmark(new, old);
626 * You should not add any new code to this function. Add it to
627 * __copy_skb_header above instead.
629 static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
631 #define C(x) n->x = skb->x
633 n->next = n->prev = NULL;
635 __copy_skb_header(n, skb);
640 n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
643 n->destructor = NULL;
649 atomic_set(&n->users, 1);
651 atomic_inc(&(skb_shinfo(skb)->dataref));
659 * skb_morph - morph one skb into another
660 * @dst: the skb to receive the contents
661 * @src: the skb to supply the contents
663 * This is identical to skb_clone except that the target skb is
664 * supplied by the user.
666 * The target skb is returned upon exit.
668 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
670 skb_release_all(dst);
671 return __skb_clone(dst, src);
673 EXPORT_SYMBOL_GPL(skb_morph);
675 /* skb_copy_ubufs - copy userspace skb frags buffers to kernel
676 * @skb: the skb to modify
677 * @gfp_mask: allocation priority
679 * This must be called on SKBTX_DEV_ZEROCOPY skb.
680 * It will copy all frags into kernel and drop the reference
681 * to userspace pages.
683 * If this function is called from an interrupt gfp_mask() must be
686 * Returns 0 on success or a negative error code on failure
687 * to allocate kernel memory to copy to.
689 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
692 int num_frags = skb_shinfo(skb)->nr_frags;
693 struct page *page, *head = NULL;
694 struct ubuf_info *uarg = skb_shinfo(skb)->destructor_arg;
696 for (i = 0; i < num_frags; i++) {
698 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
700 page = alloc_page(GFP_ATOMIC);
703 struct page *next = (struct page *)head->private;
709 vaddr = kmap_atomic(skb_frag_page(f));
710 memcpy(page_address(page),
711 vaddr + f->page_offset, skb_frag_size(f));
712 kunmap_atomic(vaddr);
713 page->private = (unsigned long)head;
717 /* skb frags release userspace buffers */
718 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
719 skb_frag_unref(skb, i);
721 uarg->callback(uarg);
723 /* skb frags point to kernel buffers */
724 for (i = skb_shinfo(skb)->nr_frags; i > 0; i--) {
725 __skb_fill_page_desc(skb, i-1, head, 0,
726 skb_shinfo(skb)->frags[i - 1].size);
727 head = (struct page *)head->private;
730 skb_shinfo(skb)->tx_flags &= ~SKBTX_DEV_ZEROCOPY;
736 * skb_clone - duplicate an sk_buff
737 * @skb: buffer to clone
738 * @gfp_mask: allocation priority
740 * Duplicate an &sk_buff. The new one is not owned by a socket. Both
741 * copies share the same packet data but not structure. The new
742 * buffer has a reference count of 1. If the allocation fails the
743 * function returns %NULL otherwise the new buffer is returned.
745 * If this function is called from an interrupt gfp_mask() must be
749 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
753 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
754 if (skb_copy_ubufs(skb, gfp_mask))
759 if (skb->fclone == SKB_FCLONE_ORIG &&
760 n->fclone == SKB_FCLONE_UNAVAILABLE) {
761 atomic_t *fclone_ref = (atomic_t *) (n + 1);
762 n->fclone = SKB_FCLONE_CLONE;
763 atomic_inc(fclone_ref);
765 n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
769 kmemcheck_annotate_bitfield(n, flags1);
770 kmemcheck_annotate_bitfield(n, flags2);
771 n->fclone = SKB_FCLONE_UNAVAILABLE;
774 return __skb_clone(n, skb);
776 EXPORT_SYMBOL(skb_clone);
778 static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
780 #ifndef NET_SKBUFF_DATA_USES_OFFSET
782 * Shift between the two data areas in bytes
784 unsigned long offset = new->data - old->data;
787 __copy_skb_header(new, old);
789 #ifndef NET_SKBUFF_DATA_USES_OFFSET
790 /* {transport,network,mac}_header are relative to skb->head */
791 new->transport_header += offset;
792 new->network_header += offset;
793 if (skb_mac_header_was_set(new))
794 new->mac_header += offset;
796 skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
797 skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
798 skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
802 * skb_copy - create private copy of an sk_buff
803 * @skb: buffer to copy
804 * @gfp_mask: allocation priority
806 * Make a copy of both an &sk_buff and its data. This is used when the
807 * caller wishes to modify the data and needs a private copy of the
808 * data to alter. Returns %NULL on failure or the pointer to the buffer
809 * on success. The returned buffer has a reference count of 1.
811 * As by-product this function converts non-linear &sk_buff to linear
812 * one, so that &sk_buff becomes completely private and caller is allowed
813 * to modify all the data of returned buffer. This means that this
814 * function is not recommended for use in circumstances when only
815 * header is going to be modified. Use pskb_copy() instead.
818 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
820 int headerlen = skb_headroom(skb);
821 unsigned int size = (skb_end_pointer(skb) - skb->head) + skb->data_len;
822 struct sk_buff *n = alloc_skb(size, gfp_mask);
827 /* Set the data pointer */
828 skb_reserve(n, headerlen);
829 /* Set the tail pointer and length */
830 skb_put(n, skb->len);
832 if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
835 copy_skb_header(n, skb);
838 EXPORT_SYMBOL(skb_copy);
841 * __pskb_copy - create copy of an sk_buff with private head.
842 * @skb: buffer to copy
843 * @headroom: headroom of new skb
844 * @gfp_mask: allocation priority
846 * Make a copy of both an &sk_buff and part of its data, located
847 * in header. Fragmented data remain shared. This is used when
848 * the caller wishes to modify only header of &sk_buff and needs
849 * private copy of the header to alter. Returns %NULL on failure
850 * or the pointer to the buffer on success.
851 * The returned buffer has a reference count of 1.
854 struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom, gfp_t gfp_mask)
856 unsigned int size = skb_headlen(skb) + headroom;
857 struct sk_buff *n = alloc_skb(size, gfp_mask);
862 /* Set the data pointer */
863 skb_reserve(n, headroom);
864 /* Set the tail pointer and length */
865 skb_put(n, skb_headlen(skb));
867 skb_copy_from_linear_data(skb, n->data, n->len);
869 n->truesize += skb->data_len;
870 n->data_len = skb->data_len;
873 if (skb_shinfo(skb)->nr_frags) {
876 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
877 if (skb_copy_ubufs(skb, gfp_mask)) {
883 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
884 skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
885 skb_frag_ref(skb, i);
887 skb_shinfo(n)->nr_frags = i;
890 if (skb_has_frag_list(skb)) {
891 skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
892 skb_clone_fraglist(n);
895 copy_skb_header(n, skb);
899 EXPORT_SYMBOL(__pskb_copy);
902 * pskb_expand_head - reallocate header of &sk_buff
903 * @skb: buffer to reallocate
904 * @nhead: room to add at head
905 * @ntail: room to add at tail
906 * @gfp_mask: allocation priority
908 * Expands (or creates identical copy, if &nhead and &ntail are zero)
909 * header of skb. &sk_buff itself is not changed. &sk_buff MUST have
910 * reference count of 1. Returns zero in the case of success or error,
911 * if expansion failed. In the last case, &sk_buff is not changed.
913 * All the pointers pointing into skb header may change and must be
914 * reloaded after call to this function.
917 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
922 int size = nhead + (skb_end_pointer(skb) - skb->head) + ntail;
931 size = SKB_DATA_ALIGN(size);
933 /* Check if we can avoid taking references on fragments if we own
934 * the last reference on skb->head. (see skb_release_data())
939 int delta = skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1;
940 fastpath = atomic_read(&skb_shinfo(skb)->dataref) == delta;
944 size + sizeof(struct skb_shared_info) <= ksize(skb->head)) {
945 memmove(skb->head + size, skb_shinfo(skb),
946 offsetof(struct skb_shared_info,
947 frags[skb_shinfo(skb)->nr_frags]));
948 memmove(skb->head + nhead, skb->head,
949 skb_tail_pointer(skb) - skb->head);
954 data = kmalloc(size + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
958 size = SKB_WITH_OVERHEAD(ksize(data));
960 /* Copy only real data... and, alas, header. This should be
961 * optimized for the cases when header is void.
963 memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);
965 memcpy((struct skb_shared_info *)(data + size),
967 offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
972 /* copy this zero copy skb frags */
973 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
974 if (skb_copy_ubufs(skb, gfp_mask))
977 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
978 skb_frag_ref(skb, i);
980 if (skb_has_frag_list(skb))
981 skb_clone_fraglist(skb);
983 skb_release_data(skb);
985 off = (data + nhead) - skb->head;
990 #ifdef NET_SKBUFF_DATA_USES_OFFSET
994 skb->end = skb->head + size;
996 /* {transport,network,mac}_header and tail are relative to skb->head */
998 skb->transport_header += off;
999 skb->network_header += off;
1000 if (skb_mac_header_was_set(skb))
1001 skb->mac_header += off;
1002 /* Only adjust this if it actually is csum_start rather than csum */
1003 if (skb->ip_summed == CHECKSUM_PARTIAL)
1004 skb->csum_start += nhead;
1008 atomic_set(&skb_shinfo(skb)->dataref, 1);
1016 EXPORT_SYMBOL(pskb_expand_head);
1018 /* Make private copy of skb with writable head and some headroom */
1020 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
1022 struct sk_buff *skb2;
1023 int delta = headroom - skb_headroom(skb);
1026 skb2 = pskb_copy(skb, GFP_ATOMIC);
1028 skb2 = skb_clone(skb, GFP_ATOMIC);
1029 if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
1037 EXPORT_SYMBOL(skb_realloc_headroom);
1040 * skb_copy_expand - copy and expand sk_buff
1041 * @skb: buffer to copy
1042 * @newheadroom: new free bytes at head
1043 * @newtailroom: new free bytes at tail
1044 * @gfp_mask: allocation priority
1046 * Make a copy of both an &sk_buff and its data and while doing so
1047 * allocate additional space.
1049 * This is used when the caller wishes to modify the data and needs a
1050 * private copy of the data to alter as well as more space for new fields.
1051 * Returns %NULL on failure or the pointer to the buffer
1052 * on success. The returned buffer has a reference count of 1.
1054 * You must pass %GFP_ATOMIC as the allocation priority if this function
1055 * is called from an interrupt.
1057 struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
1058 int newheadroom, int newtailroom,
1062 * Allocate the copy buffer
1064 struct sk_buff *n = alloc_skb(newheadroom + skb->len + newtailroom,
1066 int oldheadroom = skb_headroom(skb);
1067 int head_copy_len, head_copy_off;
1073 skb_reserve(n, newheadroom);
1075 /* Set the tail pointer and length */
1076 skb_put(n, skb->len);
1078 head_copy_len = oldheadroom;
1080 if (newheadroom <= head_copy_len)
1081 head_copy_len = newheadroom;
1083 head_copy_off = newheadroom - head_copy_len;
1085 /* Copy the linear header and data. */
1086 if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
1087 skb->len + head_copy_len))
1090 copy_skb_header(n, skb);
1092 off = newheadroom - oldheadroom;
1093 if (n->ip_summed == CHECKSUM_PARTIAL)
1094 n->csum_start += off;
1095 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1096 n->transport_header += off;
1097 n->network_header += off;
1098 if (skb_mac_header_was_set(skb))
1099 n->mac_header += off;
1104 EXPORT_SYMBOL(skb_copy_expand);
1107 * skb_pad - zero pad the tail of an skb
1108 * @skb: buffer to pad
1109 * @pad: space to pad
1111 * Ensure that a buffer is followed by a padding area that is zero
1112 * filled. Used by network drivers which may DMA or transfer data
1113 * beyond the buffer end onto the wire.
1115 * May return error in out of memory cases. The skb is freed on error.
1118 int skb_pad(struct sk_buff *skb, int pad)
1123 /* If the skbuff is non linear tailroom is always zero.. */
1124 if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
1125 memset(skb->data+skb->len, 0, pad);
1129 ntail = skb->data_len + pad - (skb->end - skb->tail);
1130 if (likely(skb_cloned(skb) || ntail > 0)) {
1131 err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
1136 /* FIXME: The use of this function with non-linear skb's really needs
1139 err = skb_linearize(skb);
1143 memset(skb->data + skb->len, 0, pad);
1150 EXPORT_SYMBOL(skb_pad);
1153 * skb_put - add data to a buffer
1154 * @skb: buffer to use
1155 * @len: amount of data to add
1157 * This function extends the used data area of the buffer. If this would
1158 * exceed the total buffer size the kernel will panic. A pointer to the
1159 * first byte of the extra data is returned.
1161 unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
1163 unsigned char *tmp = skb_tail_pointer(skb);
1164 SKB_LINEAR_ASSERT(skb);
1167 if (unlikely(skb->tail > skb->end))
1168 skb_over_panic(skb, len, __builtin_return_address(0));
1171 EXPORT_SYMBOL(skb_put);
1174 * skb_push - add data to the start of a buffer
1175 * @skb: buffer to use
1176 * @len: amount of data to add
1178 * This function extends the used data area of the buffer at the buffer
1179 * start. If this would exceed the total buffer headroom the kernel will
1180 * panic. A pointer to the first byte of the extra data is returned.
1182 unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
1186 if (unlikely(skb->data<skb->head))
1187 skb_under_panic(skb, len, __builtin_return_address(0));
1190 EXPORT_SYMBOL(skb_push);
1193 * skb_pull - remove data from the start of a buffer
1194 * @skb: buffer to use
1195 * @len: amount of data to remove
1197 * This function removes data from the start of a buffer, returning
1198 * the memory to the headroom. A pointer to the next data in the buffer
1199 * is returned. Once the data has been pulled future pushes will overwrite
1202 unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
1204 return skb_pull_inline(skb, len);
1206 EXPORT_SYMBOL(skb_pull);
1209 * skb_trim - remove end from a buffer
1210 * @skb: buffer to alter
1213 * Cut the length of a buffer down by removing data from the tail. If
1214 * the buffer is already under the length specified it is not modified.
1215 * The skb must be linear.
1217 void skb_trim(struct sk_buff *skb, unsigned int len)
1220 __skb_trim(skb, len);
1222 EXPORT_SYMBOL(skb_trim);
1224 /* Trims skb to length len. It can change skb pointers.
1227 int ___pskb_trim(struct sk_buff *skb, unsigned int len)
1229 struct sk_buff **fragp;
1230 struct sk_buff *frag;
1231 int offset = skb_headlen(skb);
1232 int nfrags = skb_shinfo(skb)->nr_frags;
1236 if (skb_cloned(skb) &&
1237 unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
1244 for (; i < nfrags; i++) {
1245 int end = offset + skb_frag_size(&skb_shinfo(skb)->frags[i]);
1252 skb_frag_size_set(&skb_shinfo(skb)->frags[i++], len - offset);
1255 skb_shinfo(skb)->nr_frags = i;
1257 for (; i < nfrags; i++)
1258 skb_frag_unref(skb, i);
1260 if (skb_has_frag_list(skb))
1261 skb_drop_fraglist(skb);
1265 for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
1266 fragp = &frag->next) {
1267 int end = offset + frag->len;
1269 if (skb_shared(frag)) {
1270 struct sk_buff *nfrag;
1272 nfrag = skb_clone(frag, GFP_ATOMIC);
1273 if (unlikely(!nfrag))
1276 nfrag->next = frag->next;
1288 unlikely((err = pskb_trim(frag, len - offset))))
1292 skb_drop_list(&frag->next);
1297 if (len > skb_headlen(skb)) {
1298 skb->data_len -= skb->len - len;
1303 skb_set_tail_pointer(skb, len);
1308 EXPORT_SYMBOL(___pskb_trim);
1311 * __pskb_pull_tail - advance tail of skb header
1312 * @skb: buffer to reallocate
1313 * @delta: number of bytes to advance tail
1315 * The function makes a sense only on a fragmented &sk_buff,
1316 * it expands header moving its tail forward and copying necessary
1317 * data from fragmented part.
1319 * &sk_buff MUST have reference count of 1.
1321 * Returns %NULL (and &sk_buff does not change) if pull failed
1322 * or value of new tail of skb in the case of success.
1324 * All the pointers pointing into skb header may change and must be
1325 * reloaded after call to this function.
1328 /* Moves tail of skb head forward, copying data from fragmented part,
1329 * when it is necessary.
1330 * 1. It may fail due to malloc failure.
1331 * 2. It may change skb pointers.
1333 * It is pretty complicated. Luckily, it is called only in exceptional cases.
1335 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
1337 /* If skb has not enough free space at tail, get new one
1338 * plus 128 bytes for future expansions. If we have enough
1339 * room at tail, reallocate without expansion only if skb is cloned.
1341 int i, k, eat = (skb->tail + delta) - skb->end;
1343 if (eat > 0 || skb_cloned(skb)) {
1344 if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
1349 if (skb_copy_bits(skb, skb_headlen(skb), skb_tail_pointer(skb), delta))
1352 /* Optimization: no fragments, no reasons to preestimate
1353 * size of pulled pages. Superb.
1355 if (!skb_has_frag_list(skb))
1358 /* Estimate size of pulled pages. */
1360 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1361 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
1368 /* If we need update frag list, we are in troubles.
1369 * Certainly, it possible to add an offset to skb data,
1370 * but taking into account that pulling is expected to
1371 * be very rare operation, it is worth to fight against
1372 * further bloating skb head and crucify ourselves here instead.
1373 * Pure masohism, indeed. 8)8)
1376 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1377 struct sk_buff *clone = NULL;
1378 struct sk_buff *insp = NULL;
1383 if (list->len <= eat) {
1384 /* Eaten as whole. */
1389 /* Eaten partially. */
1391 if (skb_shared(list)) {
1392 /* Sucks! We need to fork list. :-( */
1393 clone = skb_clone(list, GFP_ATOMIC);
1399 /* This may be pulled without
1403 if (!pskb_pull(list, eat)) {
1411 /* Free pulled out fragments. */
1412 while ((list = skb_shinfo(skb)->frag_list) != insp) {
1413 skb_shinfo(skb)->frag_list = list->next;
1416 /* And insert new clone at head. */
1419 skb_shinfo(skb)->frag_list = clone;
1422 /* Success! Now we may commit changes to skb data. */
1427 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1428 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
1431 skb_frag_unref(skb, i);
1434 skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
1436 skb_shinfo(skb)->frags[k].page_offset += eat;
1437 skb_frag_size_sub(&skb_shinfo(skb)->frags[k], eat);
1443 skb_shinfo(skb)->nr_frags = k;
1446 skb->data_len -= delta;
1448 return skb_tail_pointer(skb);
1450 EXPORT_SYMBOL(__pskb_pull_tail);
1453 * skb_copy_bits - copy bits from skb to kernel buffer
1455 * @offset: offset in source
1456 * @to: destination buffer
1457 * @len: number of bytes to copy
1459 * Copy the specified number of bytes from the source skb to the
1460 * destination buffer.
1463 * If its prototype is ever changed,
1464 * check arch/{*}/net/{*}.S files,
1465 * since it is called from BPF assembly code.
1467 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
1469 int start = skb_headlen(skb);
1470 struct sk_buff *frag_iter;
1473 if (offset > (int)skb->len - len)
1477 if ((copy = start - offset) > 0) {
1480 skb_copy_from_linear_data_offset(skb, offset, to, copy);
1481 if ((len -= copy) == 0)
1487 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1489 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
1491 WARN_ON(start > offset + len);
1493 end = start + skb_frag_size(f);
1494 if ((copy = end - offset) > 0) {
1500 vaddr = kmap_atomic(skb_frag_page(f));
1502 vaddr + f->page_offset + offset - start,
1504 kunmap_atomic(vaddr);
1506 if ((len -= copy) == 0)
1514 skb_walk_frags(skb, frag_iter) {
1517 WARN_ON(start > offset + len);
1519 end = start + frag_iter->len;
1520 if ((copy = end - offset) > 0) {
1523 if (skb_copy_bits(frag_iter, offset - start, to, copy))
1525 if ((len -= copy) == 0)
1539 EXPORT_SYMBOL(skb_copy_bits);
1542 * Callback from splice_to_pipe(), if we need to release some pages
1543 * at the end of the spd in case we error'ed out in filling the pipe.
1545 static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
1547 put_page(spd->pages[i]);
1550 static struct page *linear_to_page(struct page *page, unsigned int *len,
1551 unsigned int *offset,
1552 struct sk_buff *skb, struct sock *sk)
1554 struct page *p = sk->sk_sndmsg_page;
1559 p = sk->sk_sndmsg_page = alloc_pages(sk->sk_allocation, 0);
1563 off = sk->sk_sndmsg_off = 0;
1564 /* hold one ref to this page until it's full */
1568 /* If we are the only user of the page, we can reset offset */
1569 if (page_count(p) == 1)
1570 sk->sk_sndmsg_off = 0;
1571 off = sk->sk_sndmsg_off;
1572 mlen = PAGE_SIZE - off;
1573 if (mlen < 64 && mlen < *len) {
1578 *len = min_t(unsigned int, *len, mlen);
1581 memcpy(page_address(p) + off, page_address(page) + *offset, *len);
1582 sk->sk_sndmsg_off += *len;
1588 static bool spd_can_coalesce(const struct splice_pipe_desc *spd,
1590 unsigned int offset)
1592 return spd->nr_pages &&
1593 spd->pages[spd->nr_pages - 1] == page &&
1594 (spd->partial[spd->nr_pages - 1].offset +
1595 spd->partial[spd->nr_pages - 1].len == offset);
1599 * Fill page/offset/length into spd, if it can hold more pages.
1601 static bool spd_fill_page(struct splice_pipe_desc *spd,
1602 struct pipe_inode_info *pipe, struct page *page,
1603 unsigned int *len, unsigned int offset,
1604 struct sk_buff *skb, bool linear,
1607 if (unlikely(spd->nr_pages == MAX_SKB_FRAGS))
1611 page = linear_to_page(page, len, &offset, skb, sk);
1615 if (spd_can_coalesce(spd, page, offset)) {
1616 spd->partial[spd->nr_pages - 1].len += *len;
1620 spd->pages[spd->nr_pages] = page;
1621 spd->partial[spd->nr_pages].len = *len;
1622 spd->partial[spd->nr_pages].offset = offset;
1628 static inline void __segment_seek(struct page **page, unsigned int *poff,
1629 unsigned int *plen, unsigned int off)
1634 n = *poff / PAGE_SIZE;
1636 *page = nth_page(*page, n);
1638 *poff = *poff % PAGE_SIZE;
1642 static bool __splice_segment(struct page *page, unsigned int poff,
1643 unsigned int plen, unsigned int *off,
1644 unsigned int *len, struct sk_buff *skb,
1645 struct splice_pipe_desc *spd, bool linear,
1647 struct pipe_inode_info *pipe)
1652 /* skip this segment if already processed */
1658 /* ignore any bits we already processed */
1660 __segment_seek(&page, &poff, &plen, *off);
1665 unsigned int flen = min(*len, plen);
1667 /* the linear region may spread across several pages */
1668 flen = min_t(unsigned int, flen, PAGE_SIZE - poff);
1670 if (spd_fill_page(spd, pipe, page, &flen, poff, skb, linear, sk))
1673 __segment_seek(&page, &poff, &plen, flen);
1676 } while (*len && plen);
1682 * Map linear and fragment data from the skb to spd. It reports true if the
1683 * pipe is full or if we already spliced the requested length.
1685 static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
1686 unsigned int *offset, unsigned int *len,
1687 struct splice_pipe_desc *spd, struct sock *sk)
1692 * map the linear part
1694 if (__splice_segment(virt_to_page(skb->data),
1695 (unsigned long) skb->data & (PAGE_SIZE - 1),
1697 offset, len, skb, spd, true, sk, pipe))
1701 * then map the fragments
1703 for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
1704 const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
1706 if (__splice_segment(skb_frag_page(f),
1707 f->page_offset, skb_frag_size(f),
1708 offset, len, skb, spd, false, sk, pipe))
1716 * Map data from the skb to a pipe. Should handle both the linear part,
1717 * the fragments, and the frag list. It does NOT handle frag lists within
1718 * the frag list, if such a thing exists. We'd probably need to recurse to
1719 * handle that cleanly.
1721 int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
1722 struct pipe_inode_info *pipe, unsigned int tlen,
1725 struct partial_page partial[MAX_SKB_FRAGS];
1726 struct page *pages[MAX_SKB_FRAGS];
1727 struct splice_pipe_desc spd = {
1731 .ops = &sock_pipe_buf_ops,
1732 .spd_release = sock_spd_release,
1734 struct sk_buff *frag_iter;
1735 struct sock *sk = skb->sk;
1739 * __skb_splice_bits() only fails if the output has no room left,
1740 * so no point in going over the frag_list for the error case.
1742 if (__skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk))
1748 * now see if we have a frag_list to map
1750 skb_walk_frags(skb, frag_iter) {
1753 if (__skb_splice_bits(frag_iter, pipe, &offset, &tlen, &spd, sk))
1760 * Drop the socket lock, otherwise we have reverse
1761 * locking dependencies between sk_lock and i_mutex
1762 * here as compared to sendfile(). We enter here
1763 * with the socket lock held, and splice_to_pipe() will
1764 * grab the pipe inode lock. For sendfile() emulation,
1765 * we call into ->sendpage() with the i_mutex lock held
1766 * and networking will grab the socket lock.
1769 ret = splice_to_pipe(pipe, &spd);
1777 * skb_store_bits - store bits from kernel buffer to skb
1778 * @skb: destination buffer
1779 * @offset: offset in destination
1780 * @from: source buffer
1781 * @len: number of bytes to copy
1783 * Copy the specified number of bytes from the source buffer to the
1784 * destination skb. This function handles all the messy bits of
1785 * traversing fragment lists and such.
1788 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
1790 int start = skb_headlen(skb);
1791 struct sk_buff *frag_iter;
1794 if (offset > (int)skb->len - len)
1797 if ((copy = start - offset) > 0) {
1800 skb_copy_to_linear_data_offset(skb, offset, from, copy);
1801 if ((len -= copy) == 0)
1807 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1808 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1811 WARN_ON(start > offset + len);
1813 end = start + skb_frag_size(frag);
1814 if ((copy = end - offset) > 0) {
1820 vaddr = kmap_atomic(skb_frag_page(frag));
1821 memcpy(vaddr + frag->page_offset + offset - start,
1823 kunmap_atomic(vaddr);
1825 if ((len -= copy) == 0)
1833 skb_walk_frags(skb, frag_iter) {
1836 WARN_ON(start > offset + len);
1838 end = start + frag_iter->len;
1839 if ((copy = end - offset) > 0) {
1842 if (skb_store_bits(frag_iter, offset - start,
1845 if ((len -= copy) == 0)
1858 EXPORT_SYMBOL(skb_store_bits);
1860 /* Checksum skb data. */
1862 __wsum skb_checksum(const struct sk_buff *skb, int offset,
1863 int len, __wsum csum)
1865 int start = skb_headlen(skb);
1866 int i, copy = start - offset;
1867 struct sk_buff *frag_iter;
1870 /* Checksum header. */
1874 csum = csum_partial(skb->data + offset, copy, csum);
1875 if ((len -= copy) == 0)
1881 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1883 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1885 WARN_ON(start > offset + len);
1887 end = start + skb_frag_size(frag);
1888 if ((copy = end - offset) > 0) {
1894 vaddr = kmap_atomic(skb_frag_page(frag));
1895 csum2 = csum_partial(vaddr + frag->page_offset +
1896 offset - start, copy, 0);
1897 kunmap_atomic(vaddr);
1898 csum = csum_block_add(csum, csum2, pos);
1907 skb_walk_frags(skb, frag_iter) {
1910 WARN_ON(start > offset + len);
1912 end = start + frag_iter->len;
1913 if ((copy = end - offset) > 0) {
1917 csum2 = skb_checksum(frag_iter, offset - start,
1919 csum = csum_block_add(csum, csum2, pos);
1920 if ((len -= copy) == 0)
1931 EXPORT_SYMBOL(skb_checksum);
1933 /* Both of above in one bottle. */
1935 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
1936 u8 *to, int len, __wsum csum)
1938 int start = skb_headlen(skb);
1939 int i, copy = start - offset;
1940 struct sk_buff *frag_iter;
1947 csum = csum_partial_copy_nocheck(skb->data + offset, to,
1949 if ((len -= copy) == 0)
1956 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1959 WARN_ON(start > offset + len);
1961 end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
1962 if ((copy = end - offset) > 0) {
1965 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1969 vaddr = kmap_atomic(skb_frag_page(frag));
1970 csum2 = csum_partial_copy_nocheck(vaddr +
1974 kunmap_atomic(vaddr);
1975 csum = csum_block_add(csum, csum2, pos);
1985 skb_walk_frags(skb, frag_iter) {
1989 WARN_ON(start > offset + len);
1991 end = start + frag_iter->len;
1992 if ((copy = end - offset) > 0) {
1995 csum2 = skb_copy_and_csum_bits(frag_iter,
1998 csum = csum_block_add(csum, csum2, pos);
1999 if ((len -= copy) == 0)
2010 EXPORT_SYMBOL(skb_copy_and_csum_bits);
2012 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
2017 if (skb->ip_summed == CHECKSUM_PARTIAL)
2018 csstart = skb_checksum_start_offset(skb);
2020 csstart = skb_headlen(skb);
2022 BUG_ON(csstart > skb_headlen(skb));
2024 skb_copy_from_linear_data(skb, to, csstart);
2027 if (csstart != skb->len)
2028 csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
2029 skb->len - csstart, 0);
2031 if (skb->ip_summed == CHECKSUM_PARTIAL) {
2032 long csstuff = csstart + skb->csum_offset;
2034 *((__sum16 *)(to + csstuff)) = csum_fold(csum);
2037 EXPORT_SYMBOL(skb_copy_and_csum_dev);
2040 * skb_dequeue - remove from the head of the queue
2041 * @list: list to dequeue from
2043 * Remove the head of the list. The list lock is taken so the function
2044 * may be used safely with other locking list functions. The head item is
2045 * returned or %NULL if the list is empty.
2048 struct sk_buff *skb_dequeue(struct sk_buff_head *list)
2050 unsigned long flags;
2051 struct sk_buff *result;
2053 spin_lock_irqsave(&list->lock, flags);
2054 result = __skb_dequeue(list);
2055 spin_unlock_irqrestore(&list->lock, flags);
2058 EXPORT_SYMBOL(skb_dequeue);
2061 * skb_dequeue_tail - remove from the tail of the queue
2062 * @list: list to dequeue from
2064 * Remove the tail of the list. The list lock is taken so the function
2065 * may be used safely with other locking list functions. The tail item is
2066 * returned or %NULL if the list is empty.
2068 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
2070 unsigned long flags;
2071 struct sk_buff *result;
2073 spin_lock_irqsave(&list->lock, flags);
2074 result = __skb_dequeue_tail(list);
2075 spin_unlock_irqrestore(&list->lock, flags);
2078 EXPORT_SYMBOL(skb_dequeue_tail);
2081 * skb_queue_purge - empty a list
2082 * @list: list to empty
2084 * Delete all buffers on an &sk_buff list. Each buffer is removed from
2085 * the list and one reference dropped. This function takes the list
2086 * lock and is atomic with respect to other list locking functions.
2088 void skb_queue_purge(struct sk_buff_head *list)
2090 struct sk_buff *skb;
2091 while ((skb = skb_dequeue(list)) != NULL)
2094 EXPORT_SYMBOL(skb_queue_purge);
2097 * skb_queue_head - queue a buffer at the list head
2098 * @list: list to use
2099 * @newsk: buffer to queue
2101 * Queue a buffer at the start of the list. This function takes the
2102 * list lock and can be used safely with other locking &sk_buff functions
2105 * A buffer cannot be placed on two lists at the same time.
2107 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
2109 unsigned long flags;
2111 spin_lock_irqsave(&list->lock, flags);
2112 __skb_queue_head(list, newsk);
2113 spin_unlock_irqrestore(&list->lock, flags);
2115 EXPORT_SYMBOL(skb_queue_head);
2118 * skb_queue_tail - queue a buffer at the list tail
2119 * @list: list to use
2120 * @newsk: buffer to queue
2122 * Queue a buffer at the tail of the list. This function takes the
2123 * list lock and can be used safely with other locking &sk_buff functions
2126 * A buffer cannot be placed on two lists at the same time.
2128 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
2130 unsigned long flags;
2132 spin_lock_irqsave(&list->lock, flags);
2133 __skb_queue_tail(list, newsk);
2134 spin_unlock_irqrestore(&list->lock, flags);
2136 EXPORT_SYMBOL(skb_queue_tail);
2139 * skb_unlink - remove a buffer from a list
2140 * @skb: buffer to remove
2141 * @list: list to use
2143 * Remove a packet from a list. The list locks are taken and this
2144 * function is atomic with respect to other list locked calls
2146 * You must know what list the SKB is on.
2148 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
2150 unsigned long flags;
2152 spin_lock_irqsave(&list->lock, flags);
2153 __skb_unlink(skb, list);
2154 spin_unlock_irqrestore(&list->lock, flags);
2156 EXPORT_SYMBOL(skb_unlink);
2159 * skb_append - append a buffer
2160 * @old: buffer to insert after
2161 * @newsk: buffer to insert
2162 * @list: list to use
2164 * Place a packet after a given packet in a list. The list locks are taken
2165 * and this function is atomic with respect to other list locked calls.
2166 * A buffer cannot be placed on two lists at the same time.
2168 void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
2170 unsigned long flags;
2172 spin_lock_irqsave(&list->lock, flags);
2173 __skb_queue_after(list, old, newsk);
2174 spin_unlock_irqrestore(&list->lock, flags);
2176 EXPORT_SYMBOL(skb_append);
2179 * skb_insert - insert a buffer
2180 * @old: buffer to insert before
2181 * @newsk: buffer to insert
2182 * @list: list to use
2184 * Place a packet before a given packet in a list. The list locks are
2185 * taken and this function is atomic with respect to other list locked
2188 * A buffer cannot be placed on two lists at the same time.
2190 void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
2192 unsigned long flags;
2194 spin_lock_irqsave(&list->lock, flags);
2195 __skb_insert(newsk, old->prev, old, list);
2196 spin_unlock_irqrestore(&list->lock, flags);
2198 EXPORT_SYMBOL(skb_insert);
2200 static inline void skb_split_inside_header(struct sk_buff *skb,
2201 struct sk_buff* skb1,
2202 const u32 len, const int pos)
2206 skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
2208 /* And move data appendix as is. */
2209 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
2210 skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
2212 skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
2213 skb_shinfo(skb)->nr_frags = 0;
2214 skb1->data_len = skb->data_len;
2215 skb1->len += skb1->data_len;
2218 skb_set_tail_pointer(skb, len);
2221 static inline void skb_split_no_header(struct sk_buff *skb,
2222 struct sk_buff* skb1,
2223 const u32 len, int pos)
2226 const int nfrags = skb_shinfo(skb)->nr_frags;
2228 skb_shinfo(skb)->nr_frags = 0;
2229 skb1->len = skb1->data_len = skb->len - len;
2231 skb->data_len = len - pos;
2233 for (i = 0; i < nfrags; i++) {
2234 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2236 if (pos + size > len) {
2237 skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
2241 * We have two variants in this case:
2242 * 1. Move all the frag to the second
2243 * part, if it is possible. F.e.
2244 * this approach is mandatory for TUX,
2245 * where splitting is expensive.
2246 * 2. Split is accurately. We make this.
2248 skb_frag_ref(skb, i);
2249 skb_shinfo(skb1)->frags[0].page_offset += len - pos;
2250 skb_frag_size_sub(&skb_shinfo(skb1)->frags[0], len - pos);
2251 skb_frag_size_set(&skb_shinfo(skb)->frags[i], len - pos);
2252 skb_shinfo(skb)->nr_frags++;
2256 skb_shinfo(skb)->nr_frags++;
2259 skb_shinfo(skb1)->nr_frags = k;
2263 * skb_split - Split fragmented skb to two parts at length len.
2264 * @skb: the buffer to split
2265 * @skb1: the buffer to receive the second part
2266 * @len: new length for skb
2268 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
2270 int pos = skb_headlen(skb);
2272 if (len < pos) /* Split line is inside header. */
2273 skb_split_inside_header(skb, skb1, len, pos);
2274 else /* Second chunk has no header, nothing to copy. */
2275 skb_split_no_header(skb, skb1, len, pos);
2277 EXPORT_SYMBOL(skb_split);
2279 /* Shifting from/to a cloned skb is a no-go.
2281 * Caller cannot keep skb_shinfo related pointers past calling here!
2283 static int skb_prepare_for_shift(struct sk_buff *skb)
2285 return skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
2289 * skb_shift - Shifts paged data partially from skb to another
2290 * @tgt: buffer into which tail data gets added
2291 * @skb: buffer from which the paged data comes from
2292 * @shiftlen: shift up to this many bytes
2294 * Attempts to shift up to shiftlen worth of bytes, which may be less than
2295 * the length of the skb, from skb to tgt. Returns number bytes shifted.
2296 * It's up to caller to free skb if everything was shifted.
2298 * If @tgt runs out of frags, the whole operation is aborted.
2300 * Skb cannot include anything else but paged data while tgt is allowed
2301 * to have non-paged data as well.
2303 * TODO: full sized shift could be optimized but that would need
2304 * specialized skb free'er to handle frags without up-to-date nr_frags.
2306 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
2308 int from, to, merge, todo;
2309 struct skb_frag_struct *fragfrom, *fragto;
2311 BUG_ON(shiftlen > skb->len);
2312 BUG_ON(skb_headlen(skb)); /* Would corrupt stream */
2316 to = skb_shinfo(tgt)->nr_frags;
2317 fragfrom = &skb_shinfo(skb)->frags[from];
2319 /* Actual merge is delayed until the point when we know we can
2320 * commit all, so that we don't have to undo partial changes
2323 !skb_can_coalesce(tgt, to, skb_frag_page(fragfrom),
2324 fragfrom->page_offset)) {
2329 todo -= skb_frag_size(fragfrom);
2331 if (skb_prepare_for_shift(skb) ||
2332 skb_prepare_for_shift(tgt))
2335 /* All previous frag pointers might be stale! */
2336 fragfrom = &skb_shinfo(skb)->frags[from];
2337 fragto = &skb_shinfo(tgt)->frags[merge];
2339 skb_frag_size_add(fragto, shiftlen);
2340 skb_frag_size_sub(fragfrom, shiftlen);
2341 fragfrom->page_offset += shiftlen;
2349 /* Skip full, not-fitting skb to avoid expensive operations */
2350 if ((shiftlen == skb->len) &&
2351 (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
2354 if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
2357 while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
2358 if (to == MAX_SKB_FRAGS)
2361 fragfrom = &skb_shinfo(skb)->frags[from];
2362 fragto = &skb_shinfo(tgt)->frags[to];
2364 if (todo >= skb_frag_size(fragfrom)) {
2365 *fragto = *fragfrom;
2366 todo -= skb_frag_size(fragfrom);
2371 __skb_frag_ref(fragfrom);
2372 fragto->page = fragfrom->page;
2373 fragto->page_offset = fragfrom->page_offset;
2374 skb_frag_size_set(fragto, todo);
2376 fragfrom->page_offset += todo;
2377 skb_frag_size_sub(fragfrom, todo);
2385 /* Ready to "commit" this state change to tgt */
2386 skb_shinfo(tgt)->nr_frags = to;
2389 fragfrom = &skb_shinfo(skb)->frags[0];
2390 fragto = &skb_shinfo(tgt)->frags[merge];
2392 skb_frag_size_add(fragto, skb_frag_size(fragfrom));
2393 __skb_frag_unref(fragfrom);
2396 /* Reposition in the original skb */
2398 while (from < skb_shinfo(skb)->nr_frags)
2399 skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
2400 skb_shinfo(skb)->nr_frags = to;
2402 BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);
2405 /* Most likely the tgt won't ever need its checksum anymore, skb on
2406 * the other hand might need it if it needs to be resent
2408 tgt->ip_summed = CHECKSUM_PARTIAL;
2409 skb->ip_summed = CHECKSUM_PARTIAL;
2411 /* Yak, is it really working this way? Some helper please? */
2412 skb->len -= shiftlen;
2413 skb->data_len -= shiftlen;
2414 skb->truesize -= shiftlen;
2415 tgt->len += shiftlen;
2416 tgt->data_len += shiftlen;
2417 tgt->truesize += shiftlen;
2423 * skb_prepare_seq_read - Prepare a sequential read of skb data
2424 * @skb: the buffer to read
2425 * @from: lower offset of data to be read
2426 * @to: upper offset of data to be read
2427 * @st: state variable
2429 * Initializes the specified state variable. Must be called before
2430 * invoking skb_seq_read() for the first time.
2432 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
2433 unsigned int to, struct skb_seq_state *st)
2435 st->lower_offset = from;
2436 st->upper_offset = to;
2437 st->root_skb = st->cur_skb = skb;
2438 st->frag_idx = st->stepped_offset = 0;
2439 st->frag_data = NULL;
2441 EXPORT_SYMBOL(skb_prepare_seq_read);
2444 * skb_seq_read - Sequentially read skb data
2445 * @consumed: number of bytes consumed by the caller so far
2446 * @data: destination pointer for data to be returned
2447 * @st: state variable
2449 * Reads a block of skb data at &consumed relative to the
2450 * lower offset specified to skb_prepare_seq_read(). Assigns
2451 * the head of the data block to &data and returns the length
2452 * of the block or 0 if the end of the skb data or the upper
2453 * offset has been reached.
2455 * The caller is not required to consume all of the data
2456 * returned, i.e. &consumed is typically set to the number
2457 * of bytes already consumed and the next call to
2458 * skb_seq_read() will return the remaining part of the block.
2460 * Note 1: The size of each block of data returned can be arbitrary,
2461 * this limitation is the cost for zerocopy seqeuental
2462 * reads of potentially non linear data.
2464 * Note 2: Fragment lists within fragments are not implemented
2465 * at the moment, state->root_skb could be replaced with
2466 * a stack for this purpose.
2468 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
2469 struct skb_seq_state *st)
2471 unsigned int block_limit, abs_offset = consumed + st->lower_offset;
2474 if (unlikely(abs_offset >= st->upper_offset))
2478 block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
2480 if (abs_offset < block_limit && !st->frag_data) {
2481 *data = st->cur_skb->data + (abs_offset - st->stepped_offset);
2482 return block_limit - abs_offset;
2485 if (st->frag_idx == 0 && !st->frag_data)
2486 st->stepped_offset += skb_headlen(st->cur_skb);
2488 while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
2489 frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
2490 block_limit = skb_frag_size(frag) + st->stepped_offset;
2492 if (abs_offset < block_limit) {
2494 st->frag_data = kmap_atomic(skb_frag_page(frag));
2496 *data = (u8 *) st->frag_data + frag->page_offset +
2497 (abs_offset - st->stepped_offset);
2499 return block_limit - abs_offset;
2502 if (st->frag_data) {
2503 kunmap_atomic(st->frag_data);
2504 st->frag_data = NULL;
2508 st->stepped_offset += skb_frag_size(frag);
2511 if (st->frag_data) {
2512 kunmap_atomic(st->frag_data);
2513 st->frag_data = NULL;
2516 if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) {
2517 st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
2520 } else if (st->cur_skb->next) {
2521 st->cur_skb = st->cur_skb->next;
2528 EXPORT_SYMBOL(skb_seq_read);
2531 * skb_abort_seq_read - Abort a sequential read of skb data
2532 * @st: state variable
2534 * Must be called if skb_seq_read() was not called until it
2537 void skb_abort_seq_read(struct skb_seq_state *st)
2540 kunmap_atomic(st->frag_data);
2542 EXPORT_SYMBOL(skb_abort_seq_read);
2544 #define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb))
2546 static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
2547 struct ts_config *conf,
2548 struct ts_state *state)
2550 return skb_seq_read(offset, text, TS_SKB_CB(state));
2553 static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
2555 skb_abort_seq_read(TS_SKB_CB(state));
2559 * skb_find_text - Find a text pattern in skb data
2560 * @skb: the buffer to look in
2561 * @from: search offset
2563 * @config: textsearch configuration
2564 * @state: uninitialized textsearch state variable
2566 * Finds a pattern in the skb data according to the specified
2567 * textsearch configuration. Use textsearch_next() to retrieve
2568 * subsequent occurrences of the pattern. Returns the offset
2569 * to the first occurrence or UINT_MAX if no match was found.
2571 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
2572 unsigned int to, struct ts_config *config,
2573 struct ts_state *state)
2577 config->get_next_block = skb_ts_get_next_block;
2578 config->finish = skb_ts_finish;
2580 skb_prepare_seq_read(skb, from, to, TS_SKB_CB(state));
2582 ret = textsearch_find(config, state);
2583 return (ret <= to - from ? ret : UINT_MAX);
2585 EXPORT_SYMBOL(skb_find_text);
2588 * skb_append_datato_frags: - append the user data to a skb
2589 * @sk: sock structure
2590 * @skb: skb structure to be appened with user data.
2591 * @getfrag: call back function to be used for getting the user data
2592 * @from: pointer to user message iov
2593 * @length: length of the iov message
2595 * Description: This procedure append the user data in the fragment part
2596 * of the skb if any page alloc fails user this procedure returns -ENOMEM
2598 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
2599 int (*getfrag)(void *from, char *to, int offset,
2600 int len, int odd, struct sk_buff *skb),
2601 void *from, int length)
2604 skb_frag_t *frag = NULL;
2605 struct page *page = NULL;
2611 /* Return error if we don't have space for new frag */
2612 frg_cnt = skb_shinfo(skb)->nr_frags;
2613 if (frg_cnt >= MAX_SKB_FRAGS)
2616 /* allocate a new page for next frag */
2617 page = alloc_pages(sk->sk_allocation, 0);
2619 /* If alloc_page fails just return failure and caller will
2620 * free previous allocated pages by doing kfree_skb()
2625 /* initialize the next frag */
2626 skb_fill_page_desc(skb, frg_cnt, page, 0, 0);
2627 skb->truesize += PAGE_SIZE;
2628 atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc);
2630 /* get the new initialized frag */
2631 frg_cnt = skb_shinfo(skb)->nr_frags;
2632 frag = &skb_shinfo(skb)->frags[frg_cnt - 1];
2634 /* copy the user data to page */
2635 left = PAGE_SIZE - frag->page_offset;
2636 copy = (length > left)? left : length;
2638 ret = getfrag(from, skb_frag_address(frag) + skb_frag_size(frag),
2639 offset, copy, 0, skb);
2643 /* copy was successful so update the size parameters */
2644 skb_frag_size_add(frag, copy);
2646 skb->data_len += copy;
2650 } while (length > 0);
2654 EXPORT_SYMBOL(skb_append_datato_frags);
2657 * skb_pull_rcsum - pull skb and update receive checksum
2658 * @skb: buffer to update
2659 * @len: length of data pulled
2661 * This function performs an skb_pull on the packet and updates
2662 * the CHECKSUM_COMPLETE checksum. It should be used on
2663 * receive path processing instead of skb_pull unless you know
2664 * that the checksum difference is zero (e.g., a valid IP header)
2665 * or you are setting ip_summed to CHECKSUM_NONE.
2667 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
2669 BUG_ON(len > skb->len);
2671 BUG_ON(skb->len < skb->data_len);
2672 skb_postpull_rcsum(skb, skb->data, len);
2673 return skb->data += len;
2675 EXPORT_SYMBOL_GPL(skb_pull_rcsum);
2678 * skb_segment - Perform protocol segmentation on skb.
2679 * @skb: buffer to segment
2680 * @features: features for the output path (see dev->features)
2682 * This function performs segmentation on the given skb. It returns
2683 * a pointer to the first in a list of new skbs for the segments.
2684 * In case of error it returns ERR_PTR(err).
2686 struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features)
2688 struct sk_buff *segs = NULL;
2689 struct sk_buff *tail = NULL;
2690 struct sk_buff *fskb = skb_shinfo(skb)->frag_list;
2691 unsigned int mss = skb_shinfo(skb)->gso_size;
2692 unsigned int doffset = skb->data - skb_mac_header(skb);
2693 unsigned int offset = doffset;
2694 unsigned int headroom;
2696 int sg = !!(features & NETIF_F_SG);
2697 int nfrags = skb_shinfo(skb)->nr_frags;
2702 __skb_push(skb, doffset);
2703 headroom = skb_headroom(skb);
2704 pos = skb_headlen(skb);
2707 struct sk_buff *nskb;
2712 len = skb->len - offset;
2716 hsize = skb_headlen(skb) - offset;
2719 if (hsize > len || !sg)
2722 if (!hsize && i >= nfrags) {
2723 BUG_ON(fskb->len != len);
2726 nskb = skb_clone(fskb, GFP_ATOMIC);
2729 if (unlikely(!nskb))
2732 hsize = skb_end_pointer(nskb) - nskb->head;
2733 if (skb_cow_head(nskb, doffset + headroom)) {
2738 nskb->truesize += skb_end_pointer(nskb) - nskb->head -
2740 skb_release_head_state(nskb);
2741 __skb_push(nskb, doffset);
2743 nskb = alloc_skb(hsize + doffset + headroom,
2746 if (unlikely(!nskb))
2749 skb_reserve(nskb, headroom);
2750 __skb_put(nskb, doffset);
2759 __copy_skb_header(nskb, skb);
2760 nskb->mac_len = skb->mac_len;
2762 /* nskb and skb might have different headroom */
2763 if (nskb->ip_summed == CHECKSUM_PARTIAL)
2764 nskb->csum_start += skb_headroom(nskb) - headroom;
2766 skb_reset_mac_header(nskb);
2767 skb_set_network_header(nskb, skb->mac_len);
2768 nskb->transport_header = (nskb->network_header +
2769 skb_network_header_len(skb));
2770 skb_copy_from_linear_data(skb, nskb->data, doffset);
2772 if (fskb != skb_shinfo(skb)->frag_list)
2776 nskb->ip_summed = CHECKSUM_NONE;
2777 nskb->csum = skb_copy_and_csum_bits(skb, offset,
2783 frag = skb_shinfo(nskb)->frags;
2785 skb_copy_from_linear_data_offset(skb, offset,
2786 skb_put(nskb, hsize), hsize);
2788 while (pos < offset + len && i < nfrags) {
2789 *frag = skb_shinfo(skb)->frags[i];
2790 __skb_frag_ref(frag);
2791 size = skb_frag_size(frag);
2794 frag->page_offset += offset - pos;
2795 skb_frag_size_sub(frag, offset - pos);
2798 skb_shinfo(nskb)->nr_frags++;
2800 if (pos + size <= offset + len) {
2804 skb_frag_size_sub(frag, pos + size - (offset + len));
2811 if (pos < offset + len) {
2812 struct sk_buff *fskb2 = fskb;
2814 BUG_ON(pos + fskb->len != offset + len);
2820 fskb2 = skb_clone(fskb2, GFP_ATOMIC);
2826 SKB_FRAG_ASSERT(nskb);
2827 skb_shinfo(nskb)->frag_list = fskb2;
2831 nskb->data_len = len - hsize;
2832 nskb->len += nskb->data_len;
2833 nskb->truesize += nskb->data_len;
2834 } while ((offset += len) < skb->len);
2839 while ((skb = segs)) {
2843 return ERR_PTR(err);
2845 EXPORT_SYMBOL_GPL(skb_segment);
2847 int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
2849 struct sk_buff *p = *head;
2850 struct sk_buff *nskb;
2851 struct skb_shared_info *skbinfo = skb_shinfo(skb);
2852 struct skb_shared_info *pinfo = skb_shinfo(p);
2853 unsigned int headroom;
2854 unsigned int len = skb_gro_len(skb);
2855 unsigned int offset = skb_gro_offset(skb);
2856 unsigned int headlen = skb_headlen(skb);
2858 if (p->len + len >= 65536)
2861 if (pinfo->frag_list)
2863 else if (headlen <= offset) {
2866 int i = skbinfo->nr_frags;
2867 int nr_frags = pinfo->nr_frags + i;
2871 if (nr_frags > MAX_SKB_FRAGS)
2874 pinfo->nr_frags = nr_frags;
2875 skbinfo->nr_frags = 0;
2877 frag = pinfo->frags + nr_frags;
2878 frag2 = skbinfo->frags + i;
2883 frag->page_offset += offset;
2884 skb_frag_size_sub(frag, offset);
2886 skb->truesize -= skb->data_len;
2887 skb->len -= skb->data_len;
2890 NAPI_GRO_CB(skb)->free = 1;
2892 } else if (skb_gro_len(p) != pinfo->gso_size)
2895 headroom = skb_headroom(p);
2896 nskb = alloc_skb(headroom + skb_gro_offset(p), GFP_ATOMIC);
2897 if (unlikely(!nskb))
2900 __copy_skb_header(nskb, p);
2901 nskb->mac_len = p->mac_len;
2903 skb_reserve(nskb, headroom);
2904 __skb_put(nskb, skb_gro_offset(p));
2906 skb_set_mac_header(nskb, skb_mac_header(p) - p->data);
2907 skb_set_network_header(nskb, skb_network_offset(p));
2908 skb_set_transport_header(nskb, skb_transport_offset(p));
2910 __skb_pull(p, skb_gro_offset(p));
2911 memcpy(skb_mac_header(nskb), skb_mac_header(p),
2912 p->data - skb_mac_header(p));
2914 *NAPI_GRO_CB(nskb) = *NAPI_GRO_CB(p);
2915 skb_shinfo(nskb)->frag_list = p;
2916 skb_shinfo(nskb)->gso_size = pinfo->gso_size;
2917 pinfo->gso_size = 0;
2918 skb_header_release(p);
2921 nskb->data_len += p->len;
2922 nskb->truesize += p->truesize;
2923 nskb->len += p->len;
2926 nskb->next = p->next;
2932 p->truesize += skb->truesize - len;
2933 if (offset > headlen) {
2934 unsigned int eat = offset - headlen;
2936 skbinfo->frags[0].page_offset += eat;
2937 skb_frag_size_sub(&skbinfo->frags[0], eat);
2938 skb->data_len -= eat;
2943 __skb_pull(skb, offset);
2945 p->prev->next = skb;
2947 skb_header_release(skb);
2950 NAPI_GRO_CB(p)->count++;
2955 NAPI_GRO_CB(skb)->same_flow = 1;
2958 EXPORT_SYMBOL_GPL(skb_gro_receive);
2960 void __init skb_init(void)
2962 skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
2963 sizeof(struct sk_buff),
2965 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
2967 skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
2968 (2*sizeof(struct sk_buff)) +
2971 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
2976 * skb_to_sgvec - Fill a scatter-gather list from a socket buffer
2977 * @skb: Socket buffer containing the buffers to be mapped
2978 * @sg: The scatter-gather list to map into
2979 * @offset: The offset into the buffer's contents to start mapping
2980 * @len: Length of buffer space to be mapped
2982 * Fill the specified scatter-gather list with mappings/pointers into a
2983 * region of the buffer space attached to a socket buffer.
2986 __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
2988 int start = skb_headlen(skb);
2989 int i, copy = start - offset;
2990 struct sk_buff *frag_iter;
2996 sg_set_buf(sg, skb->data + offset, copy);
2998 if ((len -= copy) == 0)
3003 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
3006 WARN_ON(start > offset + len);
3008 end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
3009 if ((copy = end - offset) > 0) {
3010 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
3014 sg_set_page(&sg[elt], skb_frag_page(frag), copy,
3015 frag->page_offset+offset-start);
3024 skb_walk_frags(skb, frag_iter) {
3027 WARN_ON(start > offset + len);
3029 end = start + frag_iter->len;
3030 if ((copy = end - offset) > 0) {
3033 elt += __skb_to_sgvec(frag_iter, sg+elt, offset - start,
3035 if ((len -= copy) == 0)
3045 int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
3047 int nsg = __skb_to_sgvec(skb, sg, offset, len);
3049 sg_mark_end(&sg[nsg - 1]);
3053 EXPORT_SYMBOL_GPL(skb_to_sgvec);
3056 * skb_cow_data - Check that a socket buffer's data buffers are writable
3057 * @skb: The socket buffer to check.
3058 * @tailbits: Amount of trailing space to be added
3059 * @trailer: Returned pointer to the skb where the @tailbits space begins
3061 * Make sure that the data buffers attached to a socket buffer are
3062 * writable. If they are not, private copies are made of the data buffers
3063 * and the socket buffer is set to use these instead.
3065 * If @tailbits is given, make sure that there is space to write @tailbits
3066 * bytes of data beyond current end of socket buffer. @trailer will be
3067 * set to point to the skb in which this space begins.
3069 * The number of scatterlist elements required to completely map the
3070 * COW'd and extended socket buffer will be returned.
3072 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
3076 struct sk_buff *skb1, **skb_p;
3078 /* If skb is cloned or its head is paged, reallocate
3079 * head pulling out all the pages (pages are considered not writable
3080 * at the moment even if they are anonymous).
3082 if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
3083 __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL)
3086 /* Easy case. Most of packets will go this way. */
3087 if (!skb_has_frag_list(skb)) {
3088 /* A little of trouble, not enough of space for trailer.
3089 * This should not happen, when stack is tuned to generate
3090 * good frames. OK, on miss we reallocate and reserve even more
3091 * space, 128 bytes is fair. */
3093 if (skb_tailroom(skb) < tailbits &&
3094 pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
3102 /* Misery. We are in troubles, going to mincer fragments... */
3105 skb_p = &skb_shinfo(skb)->frag_list;
3108 while ((skb1 = *skb_p) != NULL) {
3111 /* The fragment is partially pulled by someone,
3112 * this can happen on input. Copy it and everything
3115 if (skb_shared(skb1))
3118 /* If the skb is the last, worry about trailer. */
3120 if (skb1->next == NULL && tailbits) {
3121 if (skb_shinfo(skb1)->nr_frags ||
3122 skb_has_frag_list(skb1) ||
3123 skb_tailroom(skb1) < tailbits)
3124 ntail = tailbits + 128;
3130 skb_shinfo(skb1)->nr_frags ||
3131 skb_has_frag_list(skb1)) {
3132 struct sk_buff *skb2;
3134 /* Fuck, we are miserable poor guys... */
3136 skb2 = skb_copy(skb1, GFP_ATOMIC);
3138 skb2 = skb_copy_expand(skb1,
3142 if (unlikely(skb2 == NULL))
3146 skb_set_owner_w(skb2, skb1->sk);
3148 /* Looking around. Are we still alive?
3149 * OK, link new skb, drop old one */
3151 skb2->next = skb1->next;
3158 skb_p = &skb1->next;
3163 EXPORT_SYMBOL_GPL(skb_cow_data);
3165 static void sock_rmem_free(struct sk_buff *skb)
3167 struct sock *sk = skb->sk;
3169 atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
3173 * Note: We dont mem charge error packets (no sk_forward_alloc changes)
3175 int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
3179 if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
3180 (unsigned int)sk->sk_rcvbuf)
3185 skb->destructor = sock_rmem_free;
3186 atomic_add(skb->truesize, &sk->sk_rmem_alloc);
3188 /* before exiting rcu section, make sure dst is refcounted */
3191 skb_queue_tail(&sk->sk_error_queue, skb);
3192 if (!sock_flag(sk, SOCK_DEAD))
3193 sk->sk_data_ready(sk, len);
3196 EXPORT_SYMBOL(sock_queue_err_skb);
3198 void skb_tstamp_tx(struct sk_buff *orig_skb,
3199 struct skb_shared_hwtstamps *hwtstamps)
3201 struct sock *sk = orig_skb->sk;
3202 struct sock_exterr_skb *serr;
3203 struct sk_buff *skb;
3209 skb = skb_clone(orig_skb, GFP_ATOMIC);
3214 *skb_hwtstamps(skb) =
3218 * no hardware time stamps available,
3219 * so keep the shared tx_flags and only
3220 * store software time stamp
3222 skb->tstamp = ktime_get_real();
3225 serr = SKB_EXT_ERR(skb);
3226 memset(serr, 0, sizeof(*serr));
3227 serr->ee.ee_errno = ENOMSG;
3228 serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
3230 err = sock_queue_err_skb(sk, skb);
3235 EXPORT_SYMBOL_GPL(skb_tstamp_tx);
3237 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
3239 struct sock *sk = skb->sk;
3240 struct sock_exterr_skb *serr;
3243 skb->wifi_acked_valid = 1;
3244 skb->wifi_acked = acked;
3246 serr = SKB_EXT_ERR(skb);
3247 memset(serr, 0, sizeof(*serr));
3248 serr->ee.ee_errno = ENOMSG;
3249 serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS;
3251 err = sock_queue_err_skb(sk, skb);
3255 EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);
3259 * skb_partial_csum_set - set up and verify partial csum values for packet
3260 * @skb: the skb to set
3261 * @start: the number of bytes after skb->data to start checksumming.
3262 * @off: the offset from start to place the checksum.
3264 * For untrusted partially-checksummed packets, we need to make sure the values
3265 * for skb->csum_start and skb->csum_offset are valid so we don't oops.
3267 * This function checks and sets those values and skb->ip_summed: if this
3268 * returns false you should drop the packet.
3270 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
3272 if (unlikely(start > skb_headlen(skb)) ||
3273 unlikely((int)start + off > skb_headlen(skb) - 2)) {
3274 if (net_ratelimit())
3276 "bad partial csum: csum=%u/%u len=%u\n",
3277 start, off, skb_headlen(skb));
3280 skb->ip_summed = CHECKSUM_PARTIAL;
3281 skb->csum_start = skb_headroom(skb) + start;
3282 skb->csum_offset = off;
3285 EXPORT_SYMBOL_GPL(skb_partial_csum_set);
3287 void __skb_warn_lro_forwarding(const struct sk_buff *skb)
3289 if (net_ratelimit())
3290 pr_warning("%s: received packets cannot be forwarded"
3291 " while LRO is enabled\n", skb->dev->name);
3293 EXPORT_SYMBOL(__skb_warn_lro_forwarding);