skbuff.c 75.4 KB
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/*
 *	Routines having to do with the 'struct sk_buff' memory handlers.
 *
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 *	Authors:	Alan Cox <alan@lxorguk.ukuu.org.uk>
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 *			Florian La Roche <rzsfl@rz.uni-sb.de>
 *
 *	Fixes:
 *		Alan Cox	:	Fixed the worst of the load
 *					balancer bugs.
 *		Dave Platt	:	Interrupt stacking fix.
 *	Richard Kooijman	:	Timestamp fixes.
 *		Alan Cox	:	Changed buffer format.
 *		Alan Cox	:	destructor hook for AF_UNIX etc.
 *		Linus Torvalds	:	Better skb_clone.
 *		Alan Cox	:	Added skb_copy.
 *		Alan Cox	:	Added all the changed routines Linus
 *					only put in the headers
 *		Ray VanTassle	:	Fixed --skb->lock in free
 *		Alan Cox	:	skb_copy copy arp field
 *		Andi Kleen	:	slabified it.
 *		Robert Olsson	:	Removed skb_head_pool
 *
 *	NOTE:
 *		The __skb_ routines should be called with interrupts
 *	disabled, or you better be *real* sure that the operation is atomic
 *	with respect to whatever list is being frobbed (e.g. via lock_sock()
 *	or via disabling bottom half handlers, etc).
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 */

/*
 *	The functions in this file will not compile correctly with gcc 2.4.x
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
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#include <linux/kmemcheck.h>
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#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#ifdef CONFIG_NET_CLS_ACT
#include <net/pkt_sched.h>
#endif
#include <linux/string.h>
#include <linux/skbuff.h>
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#include <linux/splice.h>
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#include <linux/cache.h>
#include <linux/rtnetlink.h>
#include <linux/init.h>
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#include <linux/scatterlist.h>
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#include <linux/errqueue.h>
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#include <linux/prefetch.h>
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#include <net/protocol.h>
#include <net/dst.h>
#include <net/sock.h>
#include <net/checksum.h>
#include <net/xfrm.h>

#include <asm/uaccess.h>
#include <asm/system.h>
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#include <trace/events/skb.h>
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#include "kmap_skb.h"

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static struct kmem_cache *skbuff_head_cache __read_mostly;
static struct kmem_cache *skbuff_fclone_cache __read_mostly;
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static void sock_pipe_buf_release(struct pipe_inode_info *pipe,
				  struct pipe_buffer *buf)
{
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	put_page(buf->page);
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}

static void sock_pipe_buf_get(struct pipe_inode_info *pipe,
				struct pipe_buffer *buf)
{
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	get_page(buf->page);
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}

static int sock_pipe_buf_steal(struct pipe_inode_info *pipe,
			       struct pipe_buffer *buf)
{
	return 1;
}


/* Pipe buffer operations for a socket. */
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static const struct pipe_buf_operations sock_pipe_buf_ops = {
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	.can_merge = 0,
	.map = generic_pipe_buf_map,
	.unmap = generic_pipe_buf_unmap,
	.confirm = generic_pipe_buf_confirm,
	.release = sock_pipe_buf_release,
	.steal = sock_pipe_buf_steal,
	.get = sock_pipe_buf_get,
};

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/*
 *	Keep out-of-line to prevent kernel bloat.
 *	__builtin_return_address is not used because it is not always
 *	reliable.
 */

/**
 *	skb_over_panic	- 	private function
 *	@skb: buffer
 *	@sz: size
 *	@here: address
 *
 *	Out of line support code for skb_put(). Not user callable.
 */
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static void skb_over_panic(struct sk_buff *skb, int sz, void *here)
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{
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	printk(KERN_EMERG "skb_over_panic: text:%p len:%d put:%d head:%p "
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			  "data:%p tail:%#lx end:%#lx dev:%s\n",
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	       here, skb->len, sz, skb->head, skb->data,
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	       (unsigned long)skb->tail, (unsigned long)skb->end,
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	       skb->dev ? skb->dev->name : "<NULL>");
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	BUG();
}

/**
 *	skb_under_panic	- 	private function
 *	@skb: buffer
 *	@sz: size
 *	@here: address
 *
 *	Out of line support code for skb_push(). Not user callable.
 */

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static void skb_under_panic(struct sk_buff *skb, int sz, void *here)
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{
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	printk(KERN_EMERG "skb_under_panic: text:%p len:%d put:%d head:%p "
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			  "data:%p tail:%#lx end:%#lx dev:%s\n",
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	       here, skb->len, sz, skb->head, skb->data,
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	       (unsigned long)skb->tail, (unsigned long)skb->end,
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	       skb->dev ? skb->dev->name : "<NULL>");
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	BUG();
}

/* 	Allocate a new skbuff. We do this ourselves so we can fill in a few
 *	'private' fields and also do memory statistics to find all the
 *	[BEEP] leaks.
 *
 */

/**
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 *	__alloc_skb	-	allocate a network buffer
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 *	@size: size to allocate
 *	@gfp_mask: allocation mask
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 *	@fclone: allocate from fclone cache instead of head cache
 *		and allocate a cloned (child) skb
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 *	@node: numa node to allocate memory on
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 *
 *	Allocate a new &sk_buff. The returned buffer has no headroom and a
 *	tail room of size bytes. The object has a reference count of one.
 *	The return is the buffer. On a failure the return is %NULL.
 *
 *	Buffers may only be allocated from interrupts using a @gfp_mask of
 *	%GFP_ATOMIC.
 */
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struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
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			    int fclone, int node)
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{
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	struct kmem_cache *cache;
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	struct skb_shared_info *shinfo;
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	struct sk_buff *skb;
	u8 *data;

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	cache = fclone ? skbuff_fclone_cache : skbuff_head_cache;

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	/* Get the HEAD */
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	skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
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	if (!skb)
		goto out;
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	prefetchw(skb);
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	size = SKB_DATA_ALIGN(size);
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	data = kmalloc_node_track_caller(size + sizeof(struct skb_shared_info),
			gfp_mask, node);
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	if (!data)
		goto nodata;
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	prefetchw(data + size);
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	/*
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	 * Only clear those fields we need to clear, not those that we will
	 * actually initialise below. Hence, don't put any more fields after
	 * the tail pointer in struct sk_buff!
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	 */
	memset(skb, 0, offsetof(struct sk_buff, tail));
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	skb->truesize = size + sizeof(struct sk_buff);
	atomic_set(&skb->users, 1);
	skb->head = data;
	skb->data = data;
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	skb_reset_tail_pointer(skb);
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	skb->end = skb->tail + size;
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#ifdef NET_SKBUFF_DATA_USES_OFFSET
	skb->mac_header = ~0U;
#endif

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	/* make sure we initialize shinfo sequentially */
	shinfo = skb_shinfo(skb);
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	memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
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	atomic_set(&shinfo->dataref, 1);
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	kmemcheck_annotate_variable(shinfo->destructor_arg);
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	if (fclone) {
		struct sk_buff *child = skb + 1;
		atomic_t *fclone_ref = (atomic_t *) (child + 1);
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		kmemcheck_annotate_bitfield(child, flags1);
		kmemcheck_annotate_bitfield(child, flags2);
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		skb->fclone = SKB_FCLONE_ORIG;
		atomic_set(fclone_ref, 1);

		child->fclone = SKB_FCLONE_UNAVAILABLE;
	}
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out:
	return skb;
nodata:
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	kmem_cache_free(cache, skb);
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	skb = NULL;
	goto out;
}
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EXPORT_SYMBOL(__alloc_skb);
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/**
 *	__netdev_alloc_skb - allocate an skbuff for rx on a specific device
 *	@dev: network device to receive on
 *	@length: length to allocate
 *	@gfp_mask: get_free_pages mask, passed to alloc_skb
 *
 *	Allocate a new &sk_buff and assign it a usage count of one. The
 *	buffer has unspecified headroom built in. Users should allocate
 *	the headroom they think they need without accounting for the
 *	built in space. The built in space is used for optimisations.
 *
 *	%NULL is returned if there is no free memory.
 */
struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
		unsigned int length, gfp_t gfp_mask)
{
	struct sk_buff *skb;

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	skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, NUMA_NO_NODE);
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	if (likely(skb)) {
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		skb_reserve(skb, NET_SKB_PAD);
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		skb->dev = dev;
	}
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	return skb;
}
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EXPORT_SYMBOL(__netdev_alloc_skb);
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void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
		int size)
{
	skb_fill_page_desc(skb, i, page, off, size);
	skb->len += size;
	skb->data_len += size;
	skb->truesize += size;
}
EXPORT_SYMBOL(skb_add_rx_frag);

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/**
 *	dev_alloc_skb - allocate an skbuff for receiving
 *	@length: length to allocate
 *
 *	Allocate a new &sk_buff and assign it a usage count of one. The
 *	buffer has unspecified headroom built in. Users should allocate
 *	the headroom they think they need without accounting for the
 *	built in space. The built in space is used for optimisations.
 *
 *	%NULL is returned if there is no free memory. Although this function
 *	allocates memory it can be called from an interrupt.
 */
struct sk_buff *dev_alloc_skb(unsigned int length)
{
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	/*
	 * There is more code here than it seems:
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	 * __dev_alloc_skb is an inline
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	 */
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	return __dev_alloc_skb(length, GFP_ATOMIC);
}
EXPORT_SYMBOL(dev_alloc_skb);

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static void skb_drop_list(struct sk_buff **listp)
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{
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	struct sk_buff *list = *listp;
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	*listp = NULL;
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	do {
		struct sk_buff *this = list;
		list = list->next;
		kfree_skb(this);
	} while (list);
}

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static inline void skb_drop_fraglist(struct sk_buff *skb)
{
	skb_drop_list(&skb_shinfo(skb)->frag_list);
}

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static void skb_clone_fraglist(struct sk_buff *skb)
{
	struct sk_buff *list;

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	skb_walk_frags(skb, list)
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		skb_get(list);
}

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static void skb_release_data(struct sk_buff *skb)
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{
	if (!skb->cloned ||
	    !atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
			       &skb_shinfo(skb)->dataref)) {
		if (skb_shinfo(skb)->nr_frags) {
			int i;
			for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
				put_page(skb_shinfo(skb)->frags[i].page);
		}

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		if (skb_has_frag_list(skb))
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			skb_drop_fraglist(skb);

		kfree(skb->head);
	}
}

/*
 *	Free an skbuff by memory without cleaning the state.
 */
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static void kfree_skbmem(struct sk_buff *skb)
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{
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	struct sk_buff *other;
	atomic_t *fclone_ref;

	switch (skb->fclone) {
	case SKB_FCLONE_UNAVAILABLE:
		kmem_cache_free(skbuff_head_cache, skb);
		break;

	case SKB_FCLONE_ORIG:
		fclone_ref = (atomic_t *) (skb + 2);
		if (atomic_dec_and_test(fclone_ref))
			kmem_cache_free(skbuff_fclone_cache, skb);
		break;

	case SKB_FCLONE_CLONE:
		fclone_ref = (atomic_t *) (skb + 1);
		other = skb - 1;

		/* The clone portion is available for
		 * fast-cloning again.
		 */
		skb->fclone = SKB_FCLONE_UNAVAILABLE;

		if (atomic_dec_and_test(fclone_ref))
			kmem_cache_free(skbuff_fclone_cache, other);
		break;
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	}
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}

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static void skb_release_head_state(struct sk_buff *skb)
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{
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	skb_dst_drop(skb);
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#ifdef CONFIG_XFRM
	secpath_put(skb->sp);
#endif
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	if (skb->destructor) {
		WARN_ON(in_irq());
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		skb->destructor(skb);
	}
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#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
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	nf_conntrack_put(skb->nfct);
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#endif
#ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
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	nf_conntrack_put_reasm(skb->nfct_reasm);
#endif
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#ifdef CONFIG_BRIDGE_NETFILTER
	nf_bridge_put(skb->nf_bridge);
#endif
/* XXX: IS this still necessary? - JHS */
#ifdef CONFIG_NET_SCHED
	skb->tc_index = 0;
#ifdef CONFIG_NET_CLS_ACT
	skb->tc_verd = 0;
#endif
#endif
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}

/* Free everything but the sk_buff shell. */
static void skb_release_all(struct sk_buff *skb)
{
	skb_release_head_state(skb);
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	skb_release_data(skb);
}

/**
 *	__kfree_skb - private function
 *	@skb: buffer
 *
 *	Free an sk_buff. Release anything attached to the buffer.
 *	Clean the state. This is an internal helper function. Users should
 *	always call kfree_skb
 */
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void __kfree_skb(struct sk_buff *skb)
{
	skb_release_all(skb);
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	kfree_skbmem(skb);
}
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EXPORT_SYMBOL(__kfree_skb);
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/**
 *	kfree_skb - free an sk_buff
 *	@skb: buffer to free
 *
 *	Drop a reference to the buffer and free it if the usage count has
 *	hit zero.
 */
void kfree_skb(struct sk_buff *skb)
{
	if (unlikely(!skb))
		return;
	if (likely(atomic_read(&skb->users) == 1))
		smp_rmb();
	else if (likely(!atomic_dec_and_test(&skb->users)))
		return;
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	trace_kfree_skb(skb, __builtin_return_address(0));
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	__kfree_skb(skb);
}
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EXPORT_SYMBOL(kfree_skb);
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/**
 *	consume_skb - free an skbuff
 *	@skb: buffer to free
 *
 *	Drop a ref to the buffer and free it if the usage count has hit zero
 *	Functions identically to kfree_skb, but kfree_skb assumes that the frame
 *	is being dropped after a failure and notes that
 */
void consume_skb(struct sk_buff *skb)
{
	if (unlikely(!skb))
		return;
	if (likely(atomic_read(&skb->users) == 1))
		smp_rmb();
	else if (likely(!atomic_dec_and_test(&skb->users)))
		return;
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	trace_consume_skb(skb);
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	__kfree_skb(skb);
}
EXPORT_SYMBOL(consume_skb);

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/**
 *	skb_recycle_check - check if skb can be reused for receive
 *	@skb: buffer
 *	@skb_size: minimum receive buffer size
 *
 *	Checks that the skb passed in is not shared or cloned, and
 *	that it is linear and its head portion at least as large as
 *	skb_size so that it can be recycled as a receive buffer.
 *	If these conditions are met, this function does any necessary
 *	reference count dropping and cleans up the skbuff as if it
 *	just came from __alloc_skb().
 */
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bool skb_recycle_check(struct sk_buff *skb, int skb_size)
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{
	struct skb_shared_info *shinfo;

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	if (irqs_disabled())
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		return false;
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	if (skb_is_nonlinear(skb) || skb->fclone != SKB_FCLONE_UNAVAILABLE)
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		return false;
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	skb_size = SKB_DATA_ALIGN(skb_size + NET_SKB_PAD);
	if (skb_end_pointer(skb) - skb->head < skb_size)
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		return false;
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	if (skb_shared(skb) || skb_cloned(skb))
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		return false;
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	skb_release_head_state(skb);
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	shinfo = skb_shinfo(skb);
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	memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
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	atomic_set(&shinfo->dataref, 1);

	memset(skb, 0, offsetof(struct sk_buff, tail));
	skb->data = skb->head + NET_SKB_PAD;
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	skb_reset_tail_pointer(skb);
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	return true;
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}
EXPORT_SYMBOL(skb_recycle_check);

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static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
{
	new->tstamp		= old->tstamp;
	new->dev		= old->dev;
	new->transport_header	= old->transport_header;
	new->network_header	= old->network_header;
	new->mac_header		= old->mac_header;
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	skb_dst_copy(new, old);
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	new->rxhash		= old->rxhash;
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#ifdef CONFIG_XFRM
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	new->sp			= secpath_get(old->sp);
#endif
	memcpy(new->cb, old->cb, sizeof(old->cb));
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	new->csum		= old->csum;
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	new->local_df		= old->local_df;
	new->pkt_type		= old->pkt_type;
	new->ip_summed		= old->ip_summed;
	skb_copy_queue_mapping(new, old);
	new->priority		= old->priority;
#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
	new->ipvs_property	= old->ipvs_property;
#endif
	new->protocol		= old->protocol;
	new->mark		= old->mark;
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	new->skb_iif		= old->skb_iif;
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	__nf_copy(new, old);
#if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
    defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
	new->nf_trace		= old->nf_trace;
#endif
#ifdef CONFIG_NET_SCHED
	new->tc_index		= old->tc_index;
#ifdef CONFIG_NET_CLS_ACT
	new->tc_verd		= old->tc_verd;
#endif
#endif
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	new->vlan_tci		= old->vlan_tci;

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	skb_copy_secmark(new, old);
}

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/*
 * You should not add any new code to this function.  Add it to
 * __copy_skb_header above instead.
 */
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static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
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{
#define C(x) n->x = skb->x

	n->next = n->prev = NULL;
	n->sk = NULL;
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	__copy_skb_header(n, skb);

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	C(len);
	C(data_len);
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	C(mac_len);
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	n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
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	n->cloned = 1;
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	n->nohdr = 0;
	n->destructor = NULL;
	C(tail);
	C(end);
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	C(head);
	C(data);
	C(truesize);
	atomic_set(&n->users, 1);
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	atomic_inc(&(skb_shinfo(skb)->dataref));
	skb->cloned = 1;

	return n;
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#undef C
}

/**
 *	skb_morph	-	morph one skb into another
 *	@dst: the skb to receive the contents
 *	@src: the skb to supply the contents
 *
 *	This is identical to skb_clone except that the target skb is
 *	supplied by the user.
 *
 *	The target skb is returned upon exit.
 */
struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
{
594
	skb_release_all(dst);
H
Herbert Xu 已提交
595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626
	return __skb_clone(dst, src);
}
EXPORT_SYMBOL_GPL(skb_morph);

/**
 *	skb_clone	-	duplicate an sk_buff
 *	@skb: buffer to clone
 *	@gfp_mask: allocation priority
 *
 *	Duplicate an &sk_buff. The new one is not owned by a socket. Both
 *	copies share the same packet data but not structure. The new
 *	buffer has a reference count of 1. If the allocation fails the
 *	function returns %NULL otherwise the new buffer is returned.
 *
 *	If this function is called from an interrupt gfp_mask() must be
 *	%GFP_ATOMIC.
 */

struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
{
	struct sk_buff *n;

	n = skb + 1;
	if (skb->fclone == SKB_FCLONE_ORIG &&
	    n->fclone == SKB_FCLONE_UNAVAILABLE) {
		atomic_t *fclone_ref = (atomic_t *) (n + 1);
		n->fclone = SKB_FCLONE_CLONE;
		atomic_inc(fclone_ref);
	} else {
		n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
		if (!n)
			return NULL;
627 628 629

		kmemcheck_annotate_bitfield(n, flags1);
		kmemcheck_annotate_bitfield(n, flags2);
H
Herbert Xu 已提交
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		n->fclone = SKB_FCLONE_UNAVAILABLE;
	}

	return __skb_clone(n, skb);
L
Linus Torvalds 已提交
634
}
635
EXPORT_SYMBOL(skb_clone);
L
Linus Torvalds 已提交
636 637 638

static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
{
639
#ifndef NET_SKBUFF_DATA_USES_OFFSET
L
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640 641 642 643
	/*
	 *	Shift between the two data areas in bytes
	 */
	unsigned long offset = new->data - old->data;
644
#endif
645 646 647

	__copy_skb_header(new, old);

648 649 650 651
#ifndef NET_SKBUFF_DATA_USES_OFFSET
	/* {transport,network,mac}_header are relative to skb->head */
	new->transport_header += offset;
	new->network_header   += offset;
652 653
	if (skb_mac_header_was_set(new))
		new->mac_header	      += offset;
654
#endif
655 656 657
	skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
	skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
	skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
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}

/**
 *	skb_copy	-	create private copy of an sk_buff
 *	@skb: buffer to copy
 *	@gfp_mask: allocation priority
 *
 *	Make a copy of both an &sk_buff and its data. This is used when the
 *	caller wishes to modify the data and needs a private copy of the
 *	data to alter. Returns %NULL on failure or the pointer to the buffer
 *	on success. The returned buffer has a reference count of 1.
 *
 *	As by-product this function converts non-linear &sk_buff to linear
 *	one, so that &sk_buff becomes completely private and caller is allowed
 *	to modify all the data of returned buffer. This means that this
 *	function is not recommended for use in circumstances when only
 *	header is going to be modified. Use pskb_copy() instead.
 */

A
Al Viro 已提交
677
struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
L
Linus Torvalds 已提交
678
{
E
Eric Dumazet 已提交
679 680 681 682
	int headerlen = skb_headroom(skb);
	unsigned int size = (skb_end_pointer(skb) - skb->head) + skb->data_len;
	struct sk_buff *n = alloc_skb(size, gfp_mask);

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683 684 685 686 687 688 689 690 691 692 693 694 695 696
	if (!n)
		return NULL;

	/* Set the data pointer */
	skb_reserve(n, headerlen);
	/* Set the tail pointer and length */
	skb_put(n, skb->len);

	if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
		BUG();

	copy_skb_header(n, skb);
	return n;
}
697
EXPORT_SYMBOL(skb_copy);
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Linus Torvalds 已提交
698 699 700 701 702 703 704 705 706 707 708 709 710 711

/**
 *	pskb_copy	-	create copy of an sk_buff with private head.
 *	@skb: buffer to copy
 *	@gfp_mask: allocation priority
 *
 *	Make a copy of both an &sk_buff and part of its data, located
 *	in header. Fragmented data remain shared. This is used when
 *	the caller wishes to modify only header of &sk_buff and needs
 *	private copy of the header to alter. Returns %NULL on failure
 *	or the pointer to the buffer on success.
 *	The returned buffer has a reference count of 1.
 */

A
Al Viro 已提交
712
struct sk_buff *pskb_copy(struct sk_buff *skb, gfp_t gfp_mask)
L
Linus Torvalds 已提交
713
{
E
Eric Dumazet 已提交
714 715 716
	unsigned int size = skb_end_pointer(skb) - skb->head;
	struct sk_buff *n = alloc_skb(size, gfp_mask);

L
Linus Torvalds 已提交
717 718 719 720
	if (!n)
		goto out;

	/* Set the data pointer */
E
Eric Dumazet 已提交
721
	skb_reserve(n, skb_headroom(skb));
L
Linus Torvalds 已提交
722 723 724
	/* Set the tail pointer and length */
	skb_put(n, skb_headlen(skb));
	/* Copy the bytes */
725
	skb_copy_from_linear_data(skb, n->data, n->len);
L
Linus Torvalds 已提交
726

H
Herbert Xu 已提交
727
	n->truesize += skb->data_len;
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728 729 730 731 732 733 734 735 736 737 738 739 740
	n->data_len  = skb->data_len;
	n->len	     = skb->len;

	if (skb_shinfo(skb)->nr_frags) {
		int i;

		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
			skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
			get_page(skb_shinfo(n)->frags[i].page);
		}
		skb_shinfo(n)->nr_frags = i;
	}

741
	if (skb_has_frag_list(skb)) {
L
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742 743 744 745 746 747 748 749
		skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
		skb_clone_fraglist(n);
	}

	copy_skb_header(n, skb);
out:
	return n;
}
750
EXPORT_SYMBOL(pskb_copy);
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751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767

/**
 *	pskb_expand_head - reallocate header of &sk_buff
 *	@skb: buffer to reallocate
 *	@nhead: room to add at head
 *	@ntail: room to add at tail
 *	@gfp_mask: allocation priority
 *
 *	Expands (or creates identical copy, if &nhead and &ntail are zero)
 *	header of skb. &sk_buff itself is not changed. &sk_buff MUST have
 *	reference count of 1. Returns zero in the case of success or error,
 *	if expansion failed. In the last case, &sk_buff is not changed.
 *
 *	All the pointers pointing into skb header may change and must be
 *	reloaded after call to this function.
 */

V
Victor Fusco 已提交
768
int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
A
Al Viro 已提交
769
		     gfp_t gfp_mask)
L
Linus Torvalds 已提交
770 771 772
{
	int i;
	u8 *data;
E
Eric Dumazet 已提交
773
	int size = nhead + (skb_end_pointer(skb) - skb->head) + ntail;
L
Linus Torvalds 已提交
774
	long off;
775
	bool fastpath;
L
Linus Torvalds 已提交
776

777 778
	BUG_ON(nhead < 0);

L
Linus Torvalds 已提交
779 780 781 782 783
	if (skb_shared(skb))
		BUG();

	size = SKB_DATA_ALIGN(size);

784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805
	/* Check if we can avoid taking references on fragments if we own
	 * the last reference on skb->head. (see skb_release_data())
	 */
	if (!skb->cloned)
		fastpath = true;
	else {
		int delta = skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1;

		fastpath = atomic_read(&skb_shinfo(skb)->dataref) == delta;
	}

	if (fastpath &&
	    size + sizeof(struct skb_shared_info) <= ksize(skb->head)) {
		memmove(skb->head + size, skb_shinfo(skb),
			offsetof(struct skb_shared_info,
				 frags[skb_shinfo(skb)->nr_frags]));
		memmove(skb->head + nhead, skb->head,
			skb_tail_pointer(skb) - skb->head);
		off = nhead;
		goto adjust_others;
	}

L
Linus Torvalds 已提交
806 807 808 809 810
	data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
	if (!data)
		goto nodata;

	/* Copy only real data... and, alas, header. This should be
E
Eric Dumazet 已提交
811 812 813 814 815 816
	 * optimized for the cases when header is void.
	 */
	memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);

	memcpy((struct skb_shared_info *)(data + size),
	       skb_shinfo(skb),
817
	       offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
L
Linus Torvalds 已提交
818

819 820 821 822 823
	if (fastpath) {
		kfree(skb->head);
	} else {
		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
			get_page(skb_shinfo(skb)->frags[i].page);
L
Linus Torvalds 已提交
824

825 826
		if (skb_has_frag_list(skb))
			skb_clone_fraglist(skb);
L
Linus Torvalds 已提交
827

828 829
		skb_release_data(skb);
	}
L
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830 831 832
	off = (data + nhead) - skb->head;

	skb->head     = data;
833
adjust_others:
L
Linus Torvalds 已提交
834
	skb->data    += off;
835 836
#ifdef NET_SKBUFF_DATA_USES_OFFSET
	skb->end      = size;
837
	off           = nhead;
838 839
#else
	skb->end      = skb->head + size;
840
#endif
841 842
	/* {transport,network,mac}_header and tail are relative to skb->head */
	skb->tail	      += off;
843 844
	skb->transport_header += off;
	skb->network_header   += off;
845 846
	if (skb_mac_header_was_set(skb))
		skb->mac_header += off;
847 848 849
	/* Only adjust this if it actually is csum_start rather than csum */
	if (skb->ip_summed == CHECKSUM_PARTIAL)
		skb->csum_start += nhead;
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Linus Torvalds 已提交
850
	skb->cloned   = 0;
851
	skb->hdr_len  = 0;
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Linus Torvalds 已提交
852 853 854 855 856 857 858
	skb->nohdr    = 0;
	atomic_set(&skb_shinfo(skb)->dataref, 1);
	return 0;

nodata:
	return -ENOMEM;
}
859
EXPORT_SYMBOL(pskb_expand_head);
L
Linus Torvalds 已提交
860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879

/* Make private copy of skb with writable head and some headroom */

struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
{
	struct sk_buff *skb2;
	int delta = headroom - skb_headroom(skb);

	if (delta <= 0)
		skb2 = pskb_copy(skb, GFP_ATOMIC);
	else {
		skb2 = skb_clone(skb, GFP_ATOMIC);
		if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
					     GFP_ATOMIC)) {
			kfree_skb(skb2);
			skb2 = NULL;
		}
	}
	return skb2;
}
880
EXPORT_SYMBOL(skb_realloc_headroom);
L
Linus Torvalds 已提交
881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900

/**
 *	skb_copy_expand	-	copy and expand sk_buff
 *	@skb: buffer to copy
 *	@newheadroom: new free bytes at head
 *	@newtailroom: new free bytes at tail
 *	@gfp_mask: allocation priority
 *
 *	Make a copy of both an &sk_buff and its data and while doing so
 *	allocate additional space.
 *
 *	This is used when the caller wishes to modify the data and needs a
 *	private copy of the data to alter as well as more space for new fields.
 *	Returns %NULL on failure or the pointer to the buffer
 *	on success. The returned buffer has a reference count of 1.
 *
 *	You must pass %GFP_ATOMIC as the allocation priority if this function
 *	is called from an interrupt.
 */
struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
V
Victor Fusco 已提交
901
				int newheadroom, int newtailroom,
A
Al Viro 已提交
902
				gfp_t gfp_mask)
L
Linus Torvalds 已提交
903 904 905 906 907 908
{
	/*
	 *	Allocate the copy buffer
	 */
	struct sk_buff *n = alloc_skb(newheadroom + skb->len + newtailroom,
				      gfp_mask);
909
	int oldheadroom = skb_headroom(skb);
L
Linus Torvalds 已提交
910
	int head_copy_len, head_copy_off;
911
	int off;
L
Linus Torvalds 已提交
912 913 914 915 916 917 918 919 920

	if (!n)
		return NULL;

	skb_reserve(n, newheadroom);

	/* Set the tail pointer and length */
	skb_put(n, skb->len);

921
	head_copy_len = oldheadroom;
L
Linus Torvalds 已提交
922 923 924 925 926 927 928 929 930 931 932 933 934
	head_copy_off = 0;
	if (newheadroom <= head_copy_len)
		head_copy_len = newheadroom;
	else
		head_copy_off = newheadroom - head_copy_len;

	/* Copy the linear header and data. */
	if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
			  skb->len + head_copy_len))
		BUG();

	copy_skb_header(n, skb);

935
	off                  = newheadroom - oldheadroom;
936 937
	if (n->ip_summed == CHECKSUM_PARTIAL)
		n->csum_start += off;
938
#ifdef NET_SKBUFF_DATA_USES_OFFSET
939 940
	n->transport_header += off;
	n->network_header   += off;
941 942
	if (skb_mac_header_was_set(skb))
		n->mac_header += off;
943
#endif
944

L
Linus Torvalds 已提交
945 946
	return n;
}
947
EXPORT_SYMBOL(skb_copy_expand);
L
Linus Torvalds 已提交
948 949 950 951 952 953 954 955 956 957

/**
 *	skb_pad			-	zero pad the tail of an skb
 *	@skb: buffer to pad
 *	@pad: space to pad
 *
 *	Ensure that a buffer is followed by a padding area that is zero
 *	filled. Used by network drivers which may DMA or transfer data
 *	beyond the buffer end onto the wire.
 *
958
 *	May return error in out of memory cases. The skb is freed on error.
L
Linus Torvalds 已提交
959
 */
960

961
int skb_pad(struct sk_buff *skb, int pad)
L
Linus Torvalds 已提交
962
{
963 964
	int err;
	int ntail;
965

L
Linus Torvalds 已提交
966
	/* If the skbuff is non linear tailroom is always zero.. */
967
	if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
L
Linus Torvalds 已提交
968
		memset(skb->data+skb->len, 0, pad);
969
		return 0;
L
Linus Torvalds 已提交
970
	}
971

972
	ntail = skb->data_len + pad - (skb->end - skb->tail);
973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989
	if (likely(skb_cloned(skb) || ntail > 0)) {
		err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
		if (unlikely(err))
			goto free_skb;
	}

	/* FIXME: The use of this function with non-linear skb's really needs
	 * to be audited.
	 */
	err = skb_linearize(skb);
	if (unlikely(err))
		goto free_skb;

	memset(skb->data + skb->len, 0, pad);
	return 0;

free_skb:
L
Linus Torvalds 已提交
990
	kfree_skb(skb);
991
	return err;
992
}
993
EXPORT_SYMBOL(skb_pad);
994

995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015
/**
 *	skb_put - add data to a buffer
 *	@skb: buffer to use
 *	@len: amount of data to add
 *
 *	This function extends the used data area of the buffer. If this would
 *	exceed the total buffer size the kernel will panic. A pointer to the
 *	first byte of the extra data is returned.
 */
unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
{
	unsigned char *tmp = skb_tail_pointer(skb);
	SKB_LINEAR_ASSERT(skb);
	skb->tail += len;
	skb->len  += len;
	if (unlikely(skb->tail > skb->end))
		skb_over_panic(skb, len, __builtin_return_address(0));
	return tmp;
}
EXPORT_SYMBOL(skb_put);

1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034
/**
 *	skb_push - add data to the start of a buffer
 *	@skb: buffer to use
 *	@len: amount of data to add
 *
 *	This function extends the used data area of the buffer at the buffer
 *	start. If this would exceed the total buffer headroom the kernel will
 *	panic. A pointer to the first byte of the extra data is returned.
 */
unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
{
	skb->data -= len;
	skb->len  += len;
	if (unlikely(skb->data<skb->head))
		skb_under_panic(skb, len, __builtin_return_address(0));
	return skb->data;
}
EXPORT_SYMBOL(skb_push);

1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046
/**
 *	skb_pull - remove data from the start of a buffer
 *	@skb: buffer to use
 *	@len: amount of data to remove
 *
 *	This function removes data from the start of a buffer, returning
 *	the memory to the headroom. A pointer to the next data in the buffer
 *	is returned. Once the data has been pulled future pushes will overwrite
 *	the old data.
 */
unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
{
1047
	return skb_pull_inline(skb, len);
1048 1049 1050
}
EXPORT_SYMBOL(skb_pull);

1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066
/**
 *	skb_trim - remove end from a buffer
 *	@skb: buffer to alter
 *	@len: new length
 *
 *	Cut the length of a buffer down by removing data from the tail. If
 *	the buffer is already under the length specified it is not modified.
 *	The skb must be linear.
 */
void skb_trim(struct sk_buff *skb, unsigned int len)
{
	if (skb->len > len)
		__skb_trim(skb, len);
}
EXPORT_SYMBOL(skb_trim);

1067
/* Trims skb to length len. It can change skb pointers.
L
Linus Torvalds 已提交
1068 1069
 */

1070
int ___pskb_trim(struct sk_buff *skb, unsigned int len)
L
Linus Torvalds 已提交
1071
{
1072 1073
	struct sk_buff **fragp;
	struct sk_buff *frag;
L
Linus Torvalds 已提交
1074 1075 1076
	int offset = skb_headlen(skb);
	int nfrags = skb_shinfo(skb)->nr_frags;
	int i;
1077 1078 1079 1080 1081
	int err;

	if (skb_cloned(skb) &&
	    unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
		return err;
L
Linus Torvalds 已提交
1082

1083 1084 1085 1086 1087
	i = 0;
	if (offset >= len)
		goto drop_pages;

	for (; i < nfrags; i++) {
L
Linus Torvalds 已提交
1088
		int end = offset + skb_shinfo(skb)->frags[i].size;
1089 1090 1091 1092 1093 1094

		if (end < len) {
			offset = end;
			continue;
		}

1095
		skb_shinfo(skb)->frags[i++].size = len - offset;
1096

1097
drop_pages:
1098 1099 1100 1101 1102
		skb_shinfo(skb)->nr_frags = i;

		for (; i < nfrags; i++)
			put_page(skb_shinfo(skb)->frags[i].page);

1103
		if (skb_has_frag_list(skb))
1104
			skb_drop_fraglist(skb);
1105
		goto done;
1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119
	}

	for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
	     fragp = &frag->next) {
		int end = offset + frag->len;

		if (skb_shared(frag)) {
			struct sk_buff *nfrag;

			nfrag = skb_clone(frag, GFP_ATOMIC);
			if (unlikely(!nfrag))
				return -ENOMEM;

			nfrag->next = frag->next;
1120
			kfree_skb(frag);
1121 1122
			frag = nfrag;
			*fragp = frag;
L
Linus Torvalds 已提交
1123
		}
1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136

		if (end < len) {
			offset = end;
			continue;
		}

		if (end > len &&
		    unlikely((err = pskb_trim(frag, len - offset))))
			return err;

		if (frag->next)
			skb_drop_list(&frag->next);
		break;
L
Linus Torvalds 已提交
1137 1138
	}

1139
done:
1140
	if (len > skb_headlen(skb)) {
L
Linus Torvalds 已提交
1141 1142 1143
		skb->data_len -= skb->len - len;
		skb->len       = len;
	} else {
1144 1145
		skb->len       = len;
		skb->data_len  = 0;
1146
		skb_set_tail_pointer(skb, len);
L
Linus Torvalds 已提交
1147 1148 1149 1150
	}

	return 0;
}
1151
EXPORT_SYMBOL(___pskb_trim);
L
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1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183

/**
 *	__pskb_pull_tail - advance tail of skb header
 *	@skb: buffer to reallocate
 *	@delta: number of bytes to advance tail
 *
 *	The function makes a sense only on a fragmented &sk_buff,
 *	it expands header moving its tail forward and copying necessary
 *	data from fragmented part.
 *
 *	&sk_buff MUST have reference count of 1.
 *
 *	Returns %NULL (and &sk_buff does not change) if pull failed
 *	or value of new tail of skb in the case of success.
 *
 *	All the pointers pointing into skb header may change and must be
 *	reloaded after call to this function.
 */

/* Moves tail of skb head forward, copying data from fragmented part,
 * when it is necessary.
 * 1. It may fail due to malloc failure.
 * 2. It may change skb pointers.
 *
 * It is pretty complicated. Luckily, it is called only in exceptional cases.
 */
unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
{
	/* If skb has not enough free space at tail, get new one
	 * plus 128 bytes for future expansions. If we have enough
	 * room at tail, reallocate without expansion only if skb is cloned.
	 */
1184
	int i, k, eat = (skb->tail + delta) - skb->end;
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	if (eat > 0 || skb_cloned(skb)) {
		if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
				     GFP_ATOMIC))
			return NULL;
	}

1192
	if (skb_copy_bits(skb, skb_headlen(skb), skb_tail_pointer(skb), delta))
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		BUG();

	/* Optimization: no fragments, no reasons to preestimate
	 * size of pulled pages. Superb.
	 */
1198
	if (!skb_has_frag_list(skb))
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1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221
		goto pull_pages;

	/* Estimate size of pulled pages. */
	eat = delta;
	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
		if (skb_shinfo(skb)->frags[i].size >= eat)
			goto pull_pages;
		eat -= skb_shinfo(skb)->frags[i].size;
	}

	/* If we need update frag list, we are in troubles.
	 * Certainly, it possible to add an offset to skb data,
	 * but taking into account that pulling is expected to
	 * be very rare operation, it is worth to fight against
	 * further bloating skb head and crucify ourselves here instead.
	 * Pure masohism, indeed. 8)8)
	 */
	if (eat) {
		struct sk_buff *list = skb_shinfo(skb)->frag_list;
		struct sk_buff *clone = NULL;
		struct sk_buff *insp = NULL;

		do {
1222
			BUG_ON(!list);
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			if (list->len <= eat) {
				/* Eaten as whole. */
				eat -= list->len;
				list = list->next;
				insp = list;
			} else {
				/* Eaten partially. */

				if (skb_shared(list)) {
					/* Sucks! We need to fork list. :-( */
					clone = skb_clone(list, GFP_ATOMIC);
					if (!clone)
						return NULL;
					insp = list->next;
					list = clone;
				} else {
					/* This may be pulled without
					 * problems. */
					insp = list;
				}
				if (!pskb_pull(list, eat)) {
1245
					kfree_skb(clone);
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1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286
					return NULL;
				}
				break;
			}
		} while (eat);

		/* Free pulled out fragments. */
		while ((list = skb_shinfo(skb)->frag_list) != insp) {
			skb_shinfo(skb)->frag_list = list->next;
			kfree_skb(list);
		}
		/* And insert new clone at head. */
		if (clone) {
			clone->next = list;
			skb_shinfo(skb)->frag_list = clone;
		}
	}
	/* Success! Now we may commit changes to skb data. */

pull_pages:
	eat = delta;
	k = 0;
	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
		if (skb_shinfo(skb)->frags[i].size <= eat) {
			put_page(skb_shinfo(skb)->frags[i].page);
			eat -= skb_shinfo(skb)->frags[i].size;
		} else {
			skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
			if (eat) {
				skb_shinfo(skb)->frags[k].page_offset += eat;
				skb_shinfo(skb)->frags[k].size -= eat;
				eat = 0;
			}
			k++;
		}
	}
	skb_shinfo(skb)->nr_frags = k;

	skb->tail     += delta;
	skb->data_len -= delta;

1287
	return skb_tail_pointer(skb);
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}
1289
EXPORT_SYMBOL(__pskb_pull_tail);
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/* Copy some data bits from skb to kernel buffer. */

int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
{
1295
	int start = skb_headlen(skb);
1296 1297
	struct sk_buff *frag_iter;
	int i, copy;
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	if (offset > (int)skb->len - len)
		goto fault;

	/* Copy header. */
1303
	if ((copy = start - offset) > 0) {
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		if (copy > len)
			copy = len;
1306
		skb_copy_from_linear_data_offset(skb, offset, to, copy);
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		if ((len -= copy) == 0)
			return 0;
		offset += copy;
		to     += copy;
	}

	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1314
		int end;
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1316
		WARN_ON(start > offset + len);
1317 1318

		end = start + skb_shinfo(skb)->frags[i].size;
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1319 1320 1321 1322 1323 1324 1325 1326
		if ((copy = end - offset) > 0) {
			u8 *vaddr;

			if (copy > len)
				copy = len;

			vaddr = kmap_skb_frag(&skb_shinfo(skb)->frags[i]);
			memcpy(to,
1327 1328
			       vaddr + skb_shinfo(skb)->frags[i].page_offset+
			       offset - start, copy);
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			kunmap_skb_frag(vaddr);

			if ((len -= copy) == 0)
				return 0;
			offset += copy;
			to     += copy;
		}
1336
		start = end;
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	}

1339 1340
	skb_walk_frags(skb, frag_iter) {
		int end;
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1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353
		WARN_ON(start > offset + len);

		end = start + frag_iter->len;
		if ((copy = end - offset) > 0) {
			if (copy > len)
				copy = len;
			if (skb_copy_bits(frag_iter, offset - start, to, copy))
				goto fault;
			if ((len -= copy) == 0)
				return 0;
			offset += copy;
			to     += copy;
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1354
		}
1355
		start = end;
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	}
	if (!len)
		return 0;

fault:
	return -EFAULT;
}
1363
EXPORT_SYMBOL(skb_copy_bits);
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/*
 * Callback from splice_to_pipe(), if we need to release some pages
 * at the end of the spd in case we error'ed out in filling the pipe.
 */
static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
{
1371 1372
	put_page(spd->pages[i]);
}
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1374 1375
static inline struct page *linear_to_page(struct page *page, unsigned int *len,
					  unsigned int *offset,
1376
					  struct sk_buff *skb, struct sock *sk)
1377
{
1378 1379 1380 1381 1382 1383 1384 1385
	struct page *p = sk->sk_sndmsg_page;
	unsigned int off;

	if (!p) {
new_page:
		p = sk->sk_sndmsg_page = alloc_pages(sk->sk_allocation, 0);
		if (!p)
			return NULL;
1386

1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405
		off = sk->sk_sndmsg_off = 0;
		/* hold one ref to this page until it's full */
	} else {
		unsigned int mlen;

		off = sk->sk_sndmsg_off;
		mlen = PAGE_SIZE - off;
		if (mlen < 64 && mlen < *len) {
			put_page(p);
			goto new_page;
		}

		*len = min_t(unsigned int, *len, mlen);
	}

	memcpy(page_address(p) + off, page_address(page) + *offset, *len);
	sk->sk_sndmsg_off += *len;
	*offset = off;
	get_page(p);
1406 1407

	return p;
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}

/*
 * Fill page/offset/length into spd, if it can hold more pages.
 */
1413 1414
static inline int spd_fill_page(struct splice_pipe_desc *spd,
				struct pipe_inode_info *pipe, struct page *page,
1415
				unsigned int *len, unsigned int offset,
1416 1417
				struct sk_buff *skb, int linear,
				struct sock *sk)
J
Jens Axboe 已提交
1418
{
1419
	if (unlikely(spd->nr_pages == pipe->buffers))
J
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1420 1421
		return 1;

1422
	if (linear) {
1423
		page = linear_to_page(page, len, &offset, skb, sk);
1424 1425 1426 1427 1428
		if (!page)
			return 1;
	} else
		get_page(page);

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1429
	spd->pages[spd->nr_pages] = page;
1430
	spd->partial[spd->nr_pages].len = *len;
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1431 1432
	spd->partial[spd->nr_pages].offset = offset;
	spd->nr_pages++;
1433

J
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1434 1435 1436
	return 0;
}

1437 1438 1439
static inline void __segment_seek(struct page **page, unsigned int *poff,
				  unsigned int *plen, unsigned int off)
{
1440 1441
	unsigned long n;

1442
	*poff += off;
1443 1444 1445 1446
	n = *poff / PAGE_SIZE;
	if (n)
		*page = nth_page(*page, n);

1447 1448 1449 1450 1451 1452 1453
	*poff = *poff % PAGE_SIZE;
	*plen -= off;
}

static inline int __splice_segment(struct page *page, unsigned int poff,
				   unsigned int plen, unsigned int *off,
				   unsigned int *len, struct sk_buff *skb,
1454
				   struct splice_pipe_desc *spd, int linear,
1455 1456
				   struct sock *sk,
				   struct pipe_inode_info *pipe)
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Jens Axboe 已提交
1457
{
1458 1459 1460 1461 1462 1463 1464
	if (!*len)
		return 1;

	/* skip this segment if already processed */
	if (*off >= plen) {
		*off -= plen;
		return 0;
1465
	}
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1467 1468 1469 1470
	/* ignore any bits we already processed */
	if (*off) {
		__segment_seek(&page, &poff, &plen, *off);
		*off = 0;
J
Jens Axboe 已提交
1471 1472
	}

1473 1474
	do {
		unsigned int flen = min(*len, plen);
J
Jens Axboe 已提交
1475

1476 1477
		/* the linear region may spread across several pages  */
		flen = min_t(unsigned int, flen, PAGE_SIZE - poff);
J
Jens Axboe 已提交
1478

1479
		if (spd_fill_page(spd, pipe, page, &flen, poff, skb, linear, sk))
1480
			return 1;
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Jens Axboe 已提交
1481

1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493
		__segment_seek(&page, &poff, &plen, flen);
		*len -= flen;

	} while (*len && plen);

	return 0;
}

/*
 * Map linear and fragment data from the skb to spd. It reports failure if the
 * pipe is full or if we already spliced the requested length.
 */
1494 1495 1496
static int __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
			     unsigned int *offset, unsigned int *len,
			     struct splice_pipe_desc *spd, struct sock *sk)
1497 1498 1499 1500 1501 1502 1503 1504 1505
{
	int seg;

	/*
	 * map the linear part
	 */
	if (__splice_segment(virt_to_page(skb->data),
			     (unsigned long) skb->data & (PAGE_SIZE - 1),
			     skb_headlen(skb),
1506
			     offset, len, skb, spd, 1, sk, pipe))
1507
		return 1;
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1508 1509 1510 1511 1512 1513 1514

	/*
	 * then map the fragments
	 */
	for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
		const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];

1515
		if (__splice_segment(f->page, f->page_offset, f->size,
1516
				     offset, len, skb, spd, 0, sk, pipe))
1517
			return 1;
J
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1518 1519
	}

1520
	return 0;
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1521 1522 1523 1524 1525 1526 1527 1528
}

/*
 * Map data from the skb to a pipe. Should handle both the linear part,
 * the fragments, and the frag list. It does NOT handle frag lists within
 * the frag list, if such a thing exists. We'd probably need to recurse to
 * handle that cleanly.
 */
1529
int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
J
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1530 1531 1532
		    struct pipe_inode_info *pipe, unsigned int tlen,
		    unsigned int flags)
{
1533 1534
	struct partial_page partial[PIPE_DEF_BUFFERS];
	struct page *pages[PIPE_DEF_BUFFERS];
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1535 1536 1537 1538 1539 1540 1541
	struct splice_pipe_desc spd = {
		.pages = pages,
		.partial = partial,
		.flags = flags,
		.ops = &sock_pipe_buf_ops,
		.spd_release = sock_spd_release,
	};
1542
	struct sk_buff *frag_iter;
1543
	struct sock *sk = skb->sk;
1544 1545 1546 1547
	int ret = 0;

	if (splice_grow_spd(pipe, &spd))
		return -ENOMEM;
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1548 1549 1550 1551 1552

	/*
	 * __skb_splice_bits() only fails if the output has no room left,
	 * so no point in going over the frag_list for the error case.
	 */
1553
	if (__skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk))
J
Jens Axboe 已提交
1554 1555 1556 1557 1558 1559 1560
		goto done;
	else if (!tlen)
		goto done;

	/*
	 * now see if we have a frag_list to map
	 */
1561 1562 1563
	skb_walk_frags(skb, frag_iter) {
		if (!tlen)
			break;
1564
		if (__skb_splice_bits(frag_iter, pipe, &offset, &tlen, &spd, sk))
1565
			break;
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1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578
	}

done:
	if (spd.nr_pages) {
		/*
		 * Drop the socket lock, otherwise we have reverse
		 * locking dependencies between sk_lock and i_mutex
		 * here as compared to sendfile(). We enter here
		 * with the socket lock held, and splice_to_pipe() will
		 * grab the pipe inode lock. For sendfile() emulation,
		 * we call into ->sendpage() with the i_mutex lock held
		 * and networking will grab the socket lock.
		 */
1579
		release_sock(sk);
J
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1580
		ret = splice_to_pipe(pipe, &spd);
1581
		lock_sock(sk);
J
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1582 1583
	}

1584 1585
	splice_shrink_spd(pipe, &spd);
	return ret;
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1586 1587
}

1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599
/**
 *	skb_store_bits - store bits from kernel buffer to skb
 *	@skb: destination buffer
 *	@offset: offset in destination
 *	@from: source buffer
 *	@len: number of bytes to copy
 *
 *	Copy the specified number of bytes from the source buffer to the
 *	destination skb.  This function handles all the messy bits of
 *	traversing fragment lists and such.
 */

1600
int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
1601
{
1602
	int start = skb_headlen(skb);
1603 1604
	struct sk_buff *frag_iter;
	int i, copy;
1605 1606 1607 1608

	if (offset > (int)skb->len - len)
		goto fault;

1609
	if ((copy = start - offset) > 0) {
1610 1611
		if (copy > len)
			copy = len;
1612
		skb_copy_to_linear_data_offset(skb, offset, from, copy);
1613 1614 1615 1616 1617 1618 1619 1620
		if ((len -= copy) == 0)
			return 0;
		offset += copy;
		from += copy;
	}

	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1621 1622
		int end;

1623
		WARN_ON(start > offset + len);
1624

1625
		end = start + frag->size;
1626 1627 1628 1629 1630 1631 1632
		if ((copy = end - offset) > 0) {
			u8 *vaddr;

			if (copy > len)
				copy = len;

			vaddr = kmap_skb_frag(frag);
1633 1634
			memcpy(vaddr + frag->page_offset + offset - start,
			       from, copy);
1635 1636 1637 1638 1639 1640 1641
			kunmap_skb_frag(vaddr);

			if ((len -= copy) == 0)
				return 0;
			offset += copy;
			from += copy;
		}
1642
		start = end;
1643 1644
	}

1645 1646
	skb_walk_frags(skb, frag_iter) {
		int end;
1647

1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660
		WARN_ON(start > offset + len);

		end = start + frag_iter->len;
		if ((copy = end - offset) > 0) {
			if (copy > len)
				copy = len;
			if (skb_store_bits(frag_iter, offset - start,
					   from, copy))
				goto fault;
			if ((len -= copy) == 0)
				return 0;
			offset += copy;
			from += copy;
1661
		}
1662
		start = end;
1663 1664 1665 1666 1667 1668 1669 1670 1671
	}
	if (!len)
		return 0;

fault:
	return -EFAULT;
}
EXPORT_SYMBOL(skb_store_bits);

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1672 1673
/* Checksum skb data. */

1674 1675
__wsum skb_checksum(const struct sk_buff *skb, int offset,
			  int len, __wsum csum)
L
Linus Torvalds 已提交
1676
{
1677 1678
	int start = skb_headlen(skb);
	int i, copy = start - offset;
1679
	struct sk_buff *frag_iter;
L
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1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693
	int pos = 0;

	/* Checksum header. */
	if (copy > 0) {
		if (copy > len)
			copy = len;
		csum = csum_partial(skb->data + offset, copy, csum);
		if ((len -= copy) == 0)
			return csum;
		offset += copy;
		pos	= copy;
	}

	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1694 1695
		int end;

1696
		WARN_ON(start > offset + len);
L
Linus Torvalds 已提交
1697

1698
		end = start + skb_shinfo(skb)->frags[i].size;
L
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1699
		if ((copy = end - offset) > 0) {
1700
			__wsum csum2;
L
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1701 1702 1703 1704 1705 1706
			u8 *vaddr;
			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];

			if (copy > len)
				copy = len;
			vaddr = kmap_skb_frag(frag);
1707 1708
			csum2 = csum_partial(vaddr + frag->page_offset +
					     offset - start, copy, 0);
L
Linus Torvalds 已提交
1709 1710 1711 1712 1713 1714 1715
			kunmap_skb_frag(vaddr);
			csum = csum_block_add(csum, csum2, pos);
			if (!(len -= copy))
				return csum;
			offset += copy;
			pos    += copy;
		}
1716
		start = end;
L
Linus Torvalds 已提交
1717 1718
	}

1719 1720
	skb_walk_frags(skb, frag_iter) {
		int end;
L
Linus Torvalds 已提交
1721

1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735
		WARN_ON(start > offset + len);

		end = start + frag_iter->len;
		if ((copy = end - offset) > 0) {
			__wsum csum2;
			if (copy > len)
				copy = len;
			csum2 = skb_checksum(frag_iter, offset - start,
					     copy, 0);
			csum = csum_block_add(csum, csum2, pos);
			if ((len -= copy) == 0)
				return csum;
			offset += copy;
			pos    += copy;
L
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1736
		}
1737
		start = end;
L
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1738
	}
1739
	BUG_ON(len);
L
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1740 1741 1742

	return csum;
}
1743
EXPORT_SYMBOL(skb_checksum);
L
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1744 1745 1746

/* Both of above in one bottle. */

1747 1748
__wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
				    u8 *to, int len, __wsum csum)
L
Linus Torvalds 已提交
1749
{
1750 1751
	int start = skb_headlen(skb);
	int i, copy = start - offset;
1752
	struct sk_buff *frag_iter;
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1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768
	int pos = 0;

	/* Copy header. */
	if (copy > 0) {
		if (copy > len)
			copy = len;
		csum = csum_partial_copy_nocheck(skb->data + offset, to,
						 copy, csum);
		if ((len -= copy) == 0)
			return csum;
		offset += copy;
		to     += copy;
		pos	= copy;
	}

	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1769 1770
		int end;

1771
		WARN_ON(start > offset + len);
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1772

1773
		end = start + skb_shinfo(skb)->frags[i].size;
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1774
		if ((copy = end - offset) > 0) {
1775
			__wsum csum2;
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			u8 *vaddr;
			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];

			if (copy > len)
				copy = len;
			vaddr = kmap_skb_frag(frag);
			csum2 = csum_partial_copy_nocheck(vaddr +
1783 1784 1785
							  frag->page_offset +
							  offset - start, to,
							  copy, 0);
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			kunmap_skb_frag(vaddr);
			csum = csum_block_add(csum, csum2, pos);
			if (!(len -= copy))
				return csum;
			offset += copy;
			to     += copy;
			pos    += copy;
		}
1794
		start = end;
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	}

1797 1798 1799
	skb_walk_frags(skb, frag_iter) {
		__wsum csum2;
		int end;
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1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815
		WARN_ON(start > offset + len);

		end = start + frag_iter->len;
		if ((copy = end - offset) > 0) {
			if (copy > len)
				copy = len;
			csum2 = skb_copy_and_csum_bits(frag_iter,
						       offset - start,
						       to, copy, 0);
			csum = csum_block_add(csum, csum2, pos);
			if ((len -= copy) == 0)
				return csum;
			offset += copy;
			to     += copy;
			pos    += copy;
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1816
		}
1817
		start = end;
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1818
	}
1819
	BUG_ON(len);
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	return csum;
}
1822
EXPORT_SYMBOL(skb_copy_and_csum_bits);
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1823 1824 1825

void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
{
1826
	__wsum csum;
L
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	long csstart;

1829
	if (skb->ip_summed == CHECKSUM_PARTIAL)
1830
		csstart = skb_checksum_start_offset(skb);
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1831 1832 1833
	else
		csstart = skb_headlen(skb);

1834
	BUG_ON(csstart > skb_headlen(skb));
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1835

1836
	skb_copy_from_linear_data(skb, to, csstart);
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1837 1838 1839 1840 1841 1842

	csum = 0;
	if (csstart != skb->len)
		csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
					      skb->len - csstart, 0);

1843
	if (skb->ip_summed == CHECKSUM_PARTIAL) {
A
Al Viro 已提交
1844
		long csstuff = csstart + skb->csum_offset;
L
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1845

1846
		*((__sum16 *)(to + csstuff)) = csum_fold(csum);
L
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1847 1848
	}
}
1849
EXPORT_SYMBOL(skb_copy_and_csum_dev);
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/**
 *	skb_dequeue - remove from the head of the queue
 *	@list: list to dequeue from
 *
 *	Remove the head of the list. The list lock is taken so the function
 *	may be used safely with other locking list functions. The head item is
 *	returned or %NULL if the list is empty.
 */

struct sk_buff *skb_dequeue(struct sk_buff_head *list)
{
	unsigned long flags;
	struct sk_buff *result;

	spin_lock_irqsave(&list->lock, flags);
	result = __skb_dequeue(list);
	spin_unlock_irqrestore(&list->lock, flags);
	return result;
}
1870
EXPORT_SYMBOL(skb_dequeue);
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1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889

/**
 *	skb_dequeue_tail - remove from the tail of the queue
 *	@list: list to dequeue from
 *
 *	Remove the tail of the list. The list lock is taken so the function
 *	may be used safely with other locking list functions. The tail item is
 *	returned or %NULL if the list is empty.
 */
struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
{
	unsigned long flags;
	struct sk_buff *result;

	spin_lock_irqsave(&list->lock, flags);
	result = __skb_dequeue_tail(list);
	spin_unlock_irqrestore(&list->lock, flags);
	return result;
}
1890
EXPORT_SYMBOL(skb_dequeue_tail);
L
Linus Torvalds 已提交
1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905

/**
 *	skb_queue_purge - empty a list
 *	@list: list to empty
 *
 *	Delete all buffers on an &sk_buff list. Each buffer is removed from
 *	the list and one reference dropped. This function takes the list
 *	lock and is atomic with respect to other list locking functions.
 */
void skb_queue_purge(struct sk_buff_head *list)
{
	struct sk_buff *skb;
	while ((skb = skb_dequeue(list)) != NULL)
		kfree_skb(skb);
}
1906
EXPORT_SYMBOL(skb_queue_purge);
L
Linus Torvalds 已提交
1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926

/**
 *	skb_queue_head - queue a buffer at the list head
 *	@list: list to use
 *	@newsk: buffer to queue
 *
 *	Queue a buffer at the start of the list. This function takes the
 *	list lock and can be used safely with other locking &sk_buff functions
 *	safely.
 *
 *	A buffer cannot be placed on two lists at the same time.
 */
void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
{
	unsigned long flags;

	spin_lock_irqsave(&list->lock, flags);
	__skb_queue_head(list, newsk);
	spin_unlock_irqrestore(&list->lock, flags);
}
1927
EXPORT_SYMBOL(skb_queue_head);
L
Linus Torvalds 已提交
1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947

/**
 *	skb_queue_tail - queue a buffer at the list tail
 *	@list: list to use
 *	@newsk: buffer to queue
 *
 *	Queue a buffer at the tail of the list. This function takes the
 *	list lock and can be used safely with other locking &sk_buff functions
 *	safely.
 *
 *	A buffer cannot be placed on two lists at the same time.
 */
void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
{
	unsigned long flags;

	spin_lock_irqsave(&list->lock, flags);
	__skb_queue_tail(list, newsk);
	spin_unlock_irqrestore(&list->lock, flags);
}
1948
EXPORT_SYMBOL(skb_queue_tail);
D
David S. Miller 已提交
1949

L
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1950 1951 1952
/**
 *	skb_unlink	-	remove a buffer from a list
 *	@skb: buffer to remove
D
David S. Miller 已提交
1953
 *	@list: list to use
L
Linus Torvalds 已提交
1954
 *
D
David S. Miller 已提交
1955 1956
 *	Remove a packet from a list. The list locks are taken and this
 *	function is atomic with respect to other list locked calls
L
Linus Torvalds 已提交
1957
 *
D
David S. Miller 已提交
1958
 *	You must know what list the SKB is on.
L
Linus Torvalds 已提交
1959
 */
D
David S. Miller 已提交
1960
void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
L
Linus Torvalds 已提交
1961
{
D
David S. Miller 已提交
1962
	unsigned long flags;
L
Linus Torvalds 已提交
1963

D
David S. Miller 已提交
1964 1965 1966
	spin_lock_irqsave(&list->lock, flags);
	__skb_unlink(skb, list);
	spin_unlock_irqrestore(&list->lock, flags);
L
Linus Torvalds 已提交
1967
}
1968
EXPORT_SYMBOL(skb_unlink);
L
Linus Torvalds 已提交
1969 1970 1971 1972 1973

/**
 *	skb_append	-	append a buffer
 *	@old: buffer to insert after
 *	@newsk: buffer to insert
D
David S. Miller 已提交
1974
 *	@list: list to use
L
Linus Torvalds 已提交
1975 1976 1977 1978 1979
 *
 *	Place a packet after a given packet in a list. The list locks are taken
 *	and this function is atomic with respect to other list locked calls.
 *	A buffer cannot be placed on two lists at the same time.
 */
D
David S. Miller 已提交
1980
void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
L
Linus Torvalds 已提交
1981 1982 1983
{
	unsigned long flags;

D
David S. Miller 已提交
1984
	spin_lock_irqsave(&list->lock, flags);
1985
	__skb_queue_after(list, old, newsk);
D
David S. Miller 已提交
1986
	spin_unlock_irqrestore(&list->lock, flags);
L
Linus Torvalds 已提交
1987
}
1988
EXPORT_SYMBOL(skb_append);
L
Linus Torvalds 已提交
1989 1990 1991 1992 1993

/**
 *	skb_insert	-	insert a buffer
 *	@old: buffer to insert before
 *	@newsk: buffer to insert
D
David S. Miller 已提交
1994 1995 1996 1997 1998
 *	@list: list to use
 *
 *	Place a packet before a given packet in a list. The list locks are
 * 	taken and this function is atomic with respect to other list locked
 *	calls.
L
Linus Torvalds 已提交
1999 2000 2001
 *
 *	A buffer cannot be placed on two lists at the same time.
 */
D
David S. Miller 已提交
2002
void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
L
Linus Torvalds 已提交
2003 2004 2005
{
	unsigned long flags;

D
David S. Miller 已提交
2006 2007 2008
	spin_lock_irqsave(&list->lock, flags);
	__skb_insert(newsk, old->prev, old, list);
	spin_unlock_irqrestore(&list->lock, flags);
L
Linus Torvalds 已提交
2009
}
2010
EXPORT_SYMBOL(skb_insert);
L
Linus Torvalds 已提交
2011 2012 2013 2014 2015 2016 2017

static inline void skb_split_inside_header(struct sk_buff *skb,
					   struct sk_buff* skb1,
					   const u32 len, const int pos)
{
	int i;

2018 2019
	skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
					 pos - len);
L
Linus Torvalds 已提交
2020 2021 2022 2023 2024 2025 2026 2027 2028 2029
	/* And move data appendix as is. */
	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
		skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];

	skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
	skb_shinfo(skb)->nr_frags  = 0;
	skb1->data_len		   = skb->data_len;
	skb1->len		   += skb1->data_len;
	skb->data_len		   = 0;
	skb->len		   = len;
2030
	skb_set_tail_pointer(skb, len);
L
Linus Torvalds 已提交
2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088
}

static inline void skb_split_no_header(struct sk_buff *skb,
				       struct sk_buff* skb1,
				       const u32 len, int pos)
{
	int i, k = 0;
	const int nfrags = skb_shinfo(skb)->nr_frags;

	skb_shinfo(skb)->nr_frags = 0;
	skb1->len		  = skb1->data_len = skb->len - len;
	skb->len		  = len;
	skb->data_len		  = len - pos;

	for (i = 0; i < nfrags; i++) {
		int size = skb_shinfo(skb)->frags[i].size;

		if (pos + size > len) {
			skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];

			if (pos < len) {
				/* Split frag.
				 * We have two variants in this case:
				 * 1. Move all the frag to the second
				 *    part, if it is possible. F.e.
				 *    this approach is mandatory for TUX,
				 *    where splitting is expensive.
				 * 2. Split is accurately. We make this.
				 */
				get_page(skb_shinfo(skb)->frags[i].page);
				skb_shinfo(skb1)->frags[0].page_offset += len - pos;
				skb_shinfo(skb1)->frags[0].size -= len - pos;
				skb_shinfo(skb)->frags[i].size	= len - pos;
				skb_shinfo(skb)->nr_frags++;
			}
			k++;
		} else
			skb_shinfo(skb)->nr_frags++;
		pos += size;
	}
	skb_shinfo(skb1)->nr_frags = k;
}

/**
 * skb_split - Split fragmented skb to two parts at length len.
 * @skb: the buffer to split
 * @skb1: the buffer to receive the second part
 * @len: new length for skb
 */
void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
{
	int pos = skb_headlen(skb);

	if (len < pos)	/* Split line is inside header. */
		skb_split_inside_header(skb, skb1, len, pos);
	else		/* Second chunk has no header, nothing to copy. */
		skb_split_no_header(skb, skb1, len, pos);
}
2089
EXPORT_SYMBOL(skb_split);
L
Linus Torvalds 已提交
2090

2091 2092 2093 2094
/* Shifting from/to a cloned skb is a no-go.
 *
 * Caller cannot keep skb_shinfo related pointers past calling here!
 */
2095 2096
static int skb_prepare_for_shift(struct sk_buff *skb)
{
2097
	return skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145
}

/**
 * skb_shift - Shifts paged data partially from skb to another
 * @tgt: buffer into which tail data gets added
 * @skb: buffer from which the paged data comes from
 * @shiftlen: shift up to this many bytes
 *
 * Attempts to shift up to shiftlen worth of bytes, which may be less than
 * the length of the skb, from tgt to skb. Returns number bytes shifted.
 * It's up to caller to free skb if everything was shifted.
 *
 * If @tgt runs out of frags, the whole operation is aborted.
 *
 * Skb cannot include anything else but paged data while tgt is allowed
 * to have non-paged data as well.
 *
 * TODO: full sized shift could be optimized but that would need
 * specialized skb free'er to handle frags without up-to-date nr_frags.
 */
int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
{
	int from, to, merge, todo;
	struct skb_frag_struct *fragfrom, *fragto;

	BUG_ON(shiftlen > skb->len);
	BUG_ON(skb_headlen(skb));	/* Would corrupt stream */

	todo = shiftlen;
	from = 0;
	to = skb_shinfo(tgt)->nr_frags;
	fragfrom = &skb_shinfo(skb)->frags[from];

	/* Actual merge is delayed until the point when we know we can
	 * commit all, so that we don't have to undo partial changes
	 */
	if (!to ||
	    !skb_can_coalesce(tgt, to, fragfrom->page, fragfrom->page_offset)) {
		merge = -1;
	} else {
		merge = to - 1;

		todo -= fragfrom->size;
		if (todo < 0) {
			if (skb_prepare_for_shift(skb) ||
			    skb_prepare_for_shift(tgt))
				return 0;

2146 2147
			/* All previous frag pointers might be stale! */
			fragfrom = &skb_shinfo(skb)->frags[from];
2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232
			fragto = &skb_shinfo(tgt)->frags[merge];

			fragto->size += shiftlen;
			fragfrom->size -= shiftlen;
			fragfrom->page_offset += shiftlen;

			goto onlymerged;
		}

		from++;
	}

	/* Skip full, not-fitting skb to avoid expensive operations */
	if ((shiftlen == skb->len) &&
	    (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
		return 0;

	if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
		return 0;

	while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
		if (to == MAX_SKB_FRAGS)
			return 0;

		fragfrom = &skb_shinfo(skb)->frags[from];
		fragto = &skb_shinfo(tgt)->frags[to];

		if (todo >= fragfrom->size) {
			*fragto = *fragfrom;
			todo -= fragfrom->size;
			from++;
			to++;

		} else {
			get_page(fragfrom->page);
			fragto->page = fragfrom->page;
			fragto->page_offset = fragfrom->page_offset;
			fragto->size = todo;

			fragfrom->page_offset += todo;
			fragfrom->size -= todo;
			todo = 0;

			to++;
			break;
		}
	}

	/* Ready to "commit" this state change to tgt */
	skb_shinfo(tgt)->nr_frags = to;

	if (merge >= 0) {
		fragfrom = &skb_shinfo(skb)->frags[0];
		fragto = &skb_shinfo(tgt)->frags[merge];

		fragto->size += fragfrom->size;
		put_page(fragfrom->page);
	}

	/* Reposition in the original skb */
	to = 0;
	while (from < skb_shinfo(skb)->nr_frags)
		skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
	skb_shinfo(skb)->nr_frags = to;

	BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);

onlymerged:
	/* Most likely the tgt won't ever need its checksum anymore, skb on
	 * the other hand might need it if it needs to be resent
	 */
	tgt->ip_summed = CHECKSUM_PARTIAL;
	skb->ip_summed = CHECKSUM_PARTIAL;

	/* Yak, is it really working this way? Some helper please? */
	skb->len -= shiftlen;
	skb->data_len -= shiftlen;
	skb->truesize -= shiftlen;
	tgt->len += shiftlen;
	tgt->data_len += shiftlen;
	tgt->truesize += shiftlen;

	return shiftlen;
}

2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251
/**
 * skb_prepare_seq_read - Prepare a sequential read of skb data
 * @skb: the buffer to read
 * @from: lower offset of data to be read
 * @to: upper offset of data to be read
 * @st: state variable
 *
 * Initializes the specified state variable. Must be called before
 * invoking skb_seq_read() for the first time.
 */
void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
			  unsigned int to, struct skb_seq_state *st)
{
	st->lower_offset = from;
	st->upper_offset = to;
	st->root_skb = st->cur_skb = skb;
	st->frag_idx = st->stepped_offset = 0;
	st->frag_data = NULL;
}
2252
EXPORT_SYMBOL(skb_prepare_seq_read);
2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270

/**
 * skb_seq_read - Sequentially read skb data
 * @consumed: number of bytes consumed by the caller so far
 * @data: destination pointer for data to be returned
 * @st: state variable
 *
 * Reads a block of skb data at &consumed relative to the
 * lower offset specified to skb_prepare_seq_read(). Assigns
 * the head of the data block to &data and returns the length
 * of the block or 0 if the end of the skb data or the upper
 * offset has been reached.
 *
 * The caller is not required to consume all of the data
 * returned, i.e. &consumed is typically set to the number
 * of bytes already consumed and the next call to
 * skb_seq_read() will return the remaining part of the block.
 *
L
Lucas De Marchi 已提交
2271
 * Note 1: The size of each block of data returned can be arbitrary,
2272 2273 2274
 *       this limitation is the cost for zerocopy seqeuental
 *       reads of potentially non linear data.
 *
2275
 * Note 2: Fragment lists within fragments are not implemented
2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288
 *       at the moment, state->root_skb could be replaced with
 *       a stack for this purpose.
 */
unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
			  struct skb_seq_state *st)
{
	unsigned int block_limit, abs_offset = consumed + st->lower_offset;
	skb_frag_t *frag;

	if (unlikely(abs_offset >= st->upper_offset))
		return 0;

next_skb:
2289
	block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
2290

2291
	if (abs_offset < block_limit && !st->frag_data) {
2292
		*data = st->cur_skb->data + (abs_offset - st->stepped_offset);
2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321
		return block_limit - abs_offset;
	}

	if (st->frag_idx == 0 && !st->frag_data)
		st->stepped_offset += skb_headlen(st->cur_skb);

	while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
		frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
		block_limit = frag->size + st->stepped_offset;

		if (abs_offset < block_limit) {
			if (!st->frag_data)
				st->frag_data = kmap_skb_frag(frag);

			*data = (u8 *) st->frag_data + frag->page_offset +
				(abs_offset - st->stepped_offset);

			return block_limit - abs_offset;
		}

		if (st->frag_data) {
			kunmap_skb_frag(st->frag_data);
			st->frag_data = NULL;
		}

		st->frag_idx++;
		st->stepped_offset += frag->size;
	}

2322 2323 2324 2325 2326
	if (st->frag_data) {
		kunmap_skb_frag(st->frag_data);
		st->frag_data = NULL;
	}

2327
	if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) {
S
Shyam Iyer 已提交
2328
		st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
2329 2330
		st->frag_idx = 0;
		goto next_skb;
S
Shyam Iyer 已提交
2331 2332
	} else if (st->cur_skb->next) {
		st->cur_skb = st->cur_skb->next;
2333
		st->frag_idx = 0;
2334 2335 2336 2337 2338
		goto next_skb;
	}

	return 0;
}
2339
EXPORT_SYMBOL(skb_seq_read);
2340 2341 2342 2343 2344 2345 2346 2347 2348 2349 2350 2351 2352

/**
 * skb_abort_seq_read - Abort a sequential read of skb data
 * @st: state variable
 *
 * Must be called if skb_seq_read() was not called until it
 * returned 0.
 */
void skb_abort_seq_read(struct skb_seq_state *st)
{
	if (st->frag_data)
		kunmap_skb_frag(st->frag_data);
}
2353
EXPORT_SYMBOL(skb_abort_seq_read);
2354

2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385
#define TS_SKB_CB(state)	((struct skb_seq_state *) &((state)->cb))

static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
					  struct ts_config *conf,
					  struct ts_state *state)
{
	return skb_seq_read(offset, text, TS_SKB_CB(state));
}

static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
{
	skb_abort_seq_read(TS_SKB_CB(state));
}

/**
 * skb_find_text - Find a text pattern in skb data
 * @skb: the buffer to look in
 * @from: search offset
 * @to: search limit
 * @config: textsearch configuration
 * @state: uninitialized textsearch state variable
 *
 * Finds a pattern in the skb data according to the specified
 * textsearch configuration. Use textsearch_next() to retrieve
 * subsequent occurrences of the pattern. Returns the offset
 * to the first occurrence or UINT_MAX if no match was found.
 */
unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
			   unsigned int to, struct ts_config *config,
			   struct ts_state *state)
{
2386 2387
	unsigned int ret;

2388 2389 2390 2391 2392
	config->get_next_block = skb_ts_get_next_block;
	config->finish = skb_ts_finish;

	skb_prepare_seq_read(skb, from, to, TS_SKB_CB(state));

2393 2394
	ret = textsearch_find(config, state);
	return (ret <= to - from ? ret : UINT_MAX);
2395
}
2396
EXPORT_SYMBOL(skb_find_text);
2397

2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409
/**
 * skb_append_datato_frags: - append the user data to a skb
 * @sk: sock  structure
 * @skb: skb structure to be appened with user data.
 * @getfrag: call back function to be used for getting the user data
 * @from: pointer to user message iov
 * @length: length of the iov message
 *
 * Description: This procedure append the user data in the fragment part
 * of the skb if any page alloc fails user this procedure returns  -ENOMEM
 */
int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
2410
			int (*getfrag)(void *from, char *to, int offset,
2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425 2426 2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464 2465
					int len, int odd, struct sk_buff *skb),
			void *from, int length)
{
	int frg_cnt = 0;
	skb_frag_t *frag = NULL;
	struct page *page = NULL;
	int copy, left;
	int offset = 0;
	int ret;

	do {
		/* Return error if we don't have space for new frag */
		frg_cnt = skb_shinfo(skb)->nr_frags;
		if (frg_cnt >= MAX_SKB_FRAGS)
			return -EFAULT;

		/* allocate a new page for next frag */
		page = alloc_pages(sk->sk_allocation, 0);

		/* If alloc_page fails just return failure and caller will
		 * free previous allocated pages by doing kfree_skb()
		 */
		if (page == NULL)
			return -ENOMEM;

		/* initialize the next frag */
		skb_fill_page_desc(skb, frg_cnt, page, 0, 0);
		skb->truesize += PAGE_SIZE;
		atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc);

		/* get the new initialized frag */
		frg_cnt = skb_shinfo(skb)->nr_frags;
		frag = &skb_shinfo(skb)->frags[frg_cnt - 1];

		/* copy the user data to page */
		left = PAGE_SIZE - frag->page_offset;
		copy = (length > left)? left : length;

		ret = getfrag(from, (page_address(frag->page) +
			    frag->page_offset + frag->size),
			    offset, copy, 0, skb);
		if (ret < 0)
			return -EFAULT;

		/* copy was successful so update the size parameters */
		frag->size += copy;
		skb->len += copy;
		skb->data_len += copy;
		offset += copy;
		length -= copy;

	} while (length > 0);

	return 0;
}
2466
EXPORT_SYMBOL(skb_append_datato_frags);
2467

2468 2469 2470 2471 2472 2473
/**
 *	skb_pull_rcsum - pull skb and update receive checksum
 *	@skb: buffer to update
 *	@len: length of data pulled
 *
 *	This function performs an skb_pull on the packet and updates
2474
 *	the CHECKSUM_COMPLETE checksum.  It should be used on
2475 2476 2477
 *	receive path processing instead of skb_pull unless you know
 *	that the checksum difference is zero (e.g., a valid IP header)
 *	or you are setting ip_summed to CHECKSUM_NONE.
2478 2479 2480 2481 2482 2483 2484 2485 2486
 */
unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
{
	BUG_ON(len > skb->len);
	skb->len -= len;
	BUG_ON(skb->len < skb->data_len);
	skb_postpull_rcsum(skb, skb->data, len);
	return skb->data += len;
}
2487 2488
EXPORT_SYMBOL_GPL(skb_pull_rcsum);

H
Herbert Xu 已提交
2489 2490 2491
/**
 *	skb_segment - Perform protocol segmentation on skb.
 *	@skb: buffer to segment
2492
 *	@features: features for the output path (see dev->features)
H
Herbert Xu 已提交
2493 2494
 *
 *	This function performs segmentation on the given skb.  It returns
2495 2496
 *	a pointer to the first in a list of new skbs for the segments.
 *	In case of error it returns ERR_PTR(err).
H
Herbert Xu 已提交
2497
 */
2498
struct sk_buff *skb_segment(struct sk_buff *skb, u32 features)
H
Herbert Xu 已提交
2499 2500 2501
{
	struct sk_buff *segs = NULL;
	struct sk_buff *tail = NULL;
2502
	struct sk_buff *fskb = skb_shinfo(skb)->frag_list;
H
Herbert Xu 已提交
2503
	unsigned int mss = skb_shinfo(skb)->gso_size;
2504
	unsigned int doffset = skb->data - skb_mac_header(skb);
H
Herbert Xu 已提交
2505 2506 2507
	unsigned int offset = doffset;
	unsigned int headroom;
	unsigned int len;
2508
	int sg = !!(features & NETIF_F_SG);
H
Herbert Xu 已提交
2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520
	int nfrags = skb_shinfo(skb)->nr_frags;
	int err = -ENOMEM;
	int i = 0;
	int pos;

	__skb_push(skb, doffset);
	headroom = skb_headroom(skb);
	pos = skb_headlen(skb);

	do {
		struct sk_buff *nskb;
		skb_frag_t *frag;
2521
		int hsize;
H
Herbert Xu 已提交
2522 2523 2524 2525 2526 2527 2528 2529 2530
		int size;

		len = skb->len - offset;
		if (len > mss)
			len = mss;

		hsize = skb_headlen(skb) - offset;
		if (hsize < 0)
			hsize = 0;
2531 2532
		if (hsize > len || !sg)
			hsize = len;
H
Herbert Xu 已提交
2533

2534 2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557 2558 2559 2560 2561 2562 2563
		if (!hsize && i >= nfrags) {
			BUG_ON(fskb->len != len);

			pos += len;
			nskb = skb_clone(fskb, GFP_ATOMIC);
			fskb = fskb->next;

			if (unlikely(!nskb))
				goto err;

			hsize = skb_end_pointer(nskb) - nskb->head;
			if (skb_cow_head(nskb, doffset + headroom)) {
				kfree_skb(nskb);
				goto err;
			}

			nskb->truesize += skb_end_pointer(nskb) - nskb->head -
					  hsize;
			skb_release_head_state(nskb);
			__skb_push(nskb, doffset);
		} else {
			nskb = alloc_skb(hsize + doffset + headroom,
					 GFP_ATOMIC);

			if (unlikely(!nskb))
				goto err;

			skb_reserve(nskb, headroom);
			__skb_put(nskb, doffset);
		}
H
Herbert Xu 已提交
2564 2565 2566 2567 2568 2569 2570

		if (segs)
			tail->next = nskb;
		else
			segs = nskb;
		tail = nskb;

2571
		__copy_skb_header(nskb, skb);
H
Herbert Xu 已提交
2572 2573
		nskb->mac_len = skb->mac_len;

E
Eric Dumazet 已提交
2574 2575 2576 2577
		/* nskb and skb might have different headroom */
		if (nskb->ip_summed == CHECKSUM_PARTIAL)
			nskb->csum_start += skb_headroom(nskb) - headroom;

2578
		skb_reset_mac_header(nskb);
2579
		skb_set_network_header(nskb, skb->mac_len);
2580 2581
		nskb->transport_header = (nskb->network_header +
					  skb_network_header_len(skb));
2582 2583
		skb_copy_from_linear_data(skb, nskb->data, doffset);

H
Herbert Xu 已提交
2584
		if (fskb != skb_shinfo(skb)->frag_list)
2585 2586
			continue;

H
Herbert Xu 已提交
2587
		if (!sg) {
2588
			nskb->ip_summed = CHECKSUM_NONE;
H
Herbert Xu 已提交
2589 2590 2591 2592 2593 2594 2595 2596
			nskb->csum = skb_copy_and_csum_bits(skb, offset,
							    skb_put(nskb, len),
							    len, 0);
			continue;
		}

		frag = skb_shinfo(nskb)->frags;

2597 2598
		skb_copy_from_linear_data_offset(skb, offset,
						 skb_put(nskb, hsize), hsize);
H
Herbert Xu 已提交
2599

2600
		while (pos < offset + len && i < nfrags) {
H
Herbert Xu 已提交
2601 2602 2603 2604 2605 2606 2607 2608 2609
			*frag = skb_shinfo(skb)->frags[i];
			get_page(frag->page);
			size = frag->size;

			if (pos < offset) {
				frag->page_offset += offset - pos;
				frag->size -= offset - pos;
			}

2610
			skb_shinfo(nskb)->nr_frags++;
H
Herbert Xu 已提交
2611 2612 2613 2614 2615 2616

			if (pos + size <= offset + len) {
				i++;
				pos += size;
			} else {
				frag->size -= pos + size - (offset + len);
2617
				goto skip_fraglist;
H
Herbert Xu 已提交
2618 2619 2620 2621 2622
			}

			frag++;
		}

2623 2624 2625 2626 2627 2628 2629 2630 2631 2632 2633 2634 2635 2636 2637
		if (pos < offset + len) {
			struct sk_buff *fskb2 = fskb;

			BUG_ON(pos + fskb->len != offset + len);

			pos += fskb->len;
			fskb = fskb->next;

			if (fskb2->next) {
				fskb2 = skb_clone(fskb2, GFP_ATOMIC);
				if (!fskb2)
					goto err;
			} else
				skb_get(fskb2);

2638
			SKB_FRAG_ASSERT(nskb);
2639 2640 2641 2642
			skb_shinfo(nskb)->frag_list = fskb2;
		}

skip_fraglist:
H
Herbert Xu 已提交
2643 2644 2645 2646 2647 2648 2649 2650 2651 2652
		nskb->data_len = len - hsize;
		nskb->len += nskb->data_len;
		nskb->truesize += nskb->data_len;
	} while ((offset += len) < skb->len);

	return segs;

err:
	while ((skb = segs)) {
		segs = skb->next;
P
Patrick McHardy 已提交
2653
		kfree_skb(skb);
H
Herbert Xu 已提交
2654 2655 2656 2657 2658
	}
	return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(skb_segment);

H
Herbert Xu 已提交
2659 2660 2661 2662
int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
{
	struct sk_buff *p = *head;
	struct sk_buff *nskb;
2663 2664
	struct skb_shared_info *skbinfo = skb_shinfo(skb);
	struct skb_shared_info *pinfo = skb_shinfo(p);
H
Herbert Xu 已提交
2665
	unsigned int headroom;
2666
	unsigned int len = skb_gro_len(skb);
2667 2668
	unsigned int offset = skb_gro_offset(skb);
	unsigned int headlen = skb_headlen(skb);
H
Herbert Xu 已提交
2669

2670
	if (p->len + len >= 65536)
H
Herbert Xu 已提交
2671 2672
		return -E2BIG;

2673
	if (pinfo->frag_list)
H
Herbert Xu 已提交
2674
		goto merge;
2675
	else if (headlen <= offset) {
2676
		skb_frag_t *frag;
2677
		skb_frag_t *frag2;
2678 2679
		int i = skbinfo->nr_frags;
		int nr_frags = pinfo->nr_frags + i;
2680 2681

		offset -= headlen;
2682

2683
		if (nr_frags > MAX_SKB_FRAGS)
2684 2685
			return -E2BIG;

2686 2687
		pinfo->nr_frags = nr_frags;
		skbinfo->nr_frags = 0;
2688

2689 2690
		frag = pinfo->frags + nr_frags;
		frag2 = skbinfo->frags + i;
2691 2692 2693
		do {
			*--frag = *--frag2;
		} while (--i);
H
Herbert Xu 已提交
2694

2695 2696
		frag->page_offset += offset;
		frag->size -= offset;
2697 2698 2699 2700 2701

		skb->truesize -= skb->data_len;
		skb->len -= skb->data_len;
		skb->data_len = 0;

H
Herbert Xu 已提交
2702 2703
		NAPI_GRO_CB(skb)->free = 1;
		goto done;
2704 2705
	} else if (skb_gro_len(p) != pinfo->gso_size)
		return -E2BIG;
H
Herbert Xu 已提交
2706 2707

	headroom = skb_headroom(p);
E
Eric Dumazet 已提交
2708
	nskb = alloc_skb(headroom + skb_gro_offset(p), GFP_ATOMIC);
H
Herbert Xu 已提交
2709 2710 2711 2712 2713 2714 2715
	if (unlikely(!nskb))
		return -ENOMEM;

	__copy_skb_header(nskb, p);
	nskb->mac_len = p->mac_len;

	skb_reserve(nskb, headroom);
2716
	__skb_put(nskb, skb_gro_offset(p));
H
Herbert Xu 已提交
2717

2718
	skb_set_mac_header(nskb, skb_mac_header(p) - p->data);
H
Herbert Xu 已提交
2719 2720 2721
	skb_set_network_header(nskb, skb_network_offset(p));
	skb_set_transport_header(nskb, skb_transport_offset(p));

2722 2723 2724
	__skb_pull(p, skb_gro_offset(p));
	memcpy(skb_mac_header(nskb), skb_mac_header(p),
	       p->data - skb_mac_header(p));
H
Herbert Xu 已提交
2725 2726 2727

	*NAPI_GRO_CB(nskb) = *NAPI_GRO_CB(p);
	skb_shinfo(nskb)->frag_list = p;
2728
	skb_shinfo(nskb)->gso_size = pinfo->gso_size;
2729
	pinfo->gso_size = 0;
H
Herbert Xu 已提交
2730 2731 2732 2733 2734 2735 2736 2737 2738 2739 2740 2741 2742 2743
	skb_header_release(p);
	nskb->prev = p;

	nskb->data_len += p->len;
	nskb->truesize += p->len;
	nskb->len += p->len;

	*head = nskb;
	nskb->next = p->next;
	p->next = NULL;

	p = nskb;

merge:
2744
	if (offset > headlen) {
2745 2746 2747 2748 2749 2750
		unsigned int eat = offset - headlen;

		skbinfo->frags[0].page_offset += eat;
		skbinfo->frags[0].size -= eat;
		skb->data_len -= eat;
		skb->len -= eat;
2751
		offset = headlen;
2752 2753
	}

2754
	__skb_pull(skb, offset);
2755

H
Herbert Xu 已提交
2756 2757 2758 2759
	p->prev->next = skb;
	p->prev = skb;
	skb_header_release(skb);

H
Herbert Xu 已提交
2760 2761
done:
	NAPI_GRO_CB(p)->count++;
H
Herbert Xu 已提交
2762 2763 2764
	p->data_len += len;
	p->truesize += len;
	p->len += len;
H
Herbert Xu 已提交
2765 2766 2767 2768 2769 2770

	NAPI_GRO_CB(skb)->same_flow = 1;
	return 0;
}
EXPORT_SYMBOL_GPL(skb_gro_receive);

L
Linus Torvalds 已提交
2771 2772 2773 2774 2775
void __init skb_init(void)
{
	skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
					      sizeof(struct sk_buff),
					      0,
A
Alexey Dobriyan 已提交
2776
					      SLAB_HWCACHE_ALIGN|SLAB_PANIC,
2777
					      NULL);
2778 2779 2780 2781
	skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
						(2*sizeof(struct sk_buff)) +
						sizeof(atomic_t),
						0,
A
Alexey Dobriyan 已提交
2782
						SLAB_HWCACHE_ALIGN|SLAB_PANIC,
2783
						NULL);
L
Linus Torvalds 已提交
2784 2785
}

2786 2787 2788 2789 2790 2791 2792 2793 2794 2795
/**
 *	skb_to_sgvec - Fill a scatter-gather list from a socket buffer
 *	@skb: Socket buffer containing the buffers to be mapped
 *	@sg: The scatter-gather list to map into
 *	@offset: The offset into the buffer's contents to start mapping
 *	@len: Length of buffer space to be mapped
 *
 *	Fill the specified scatter-gather list with mappings/pointers into a
 *	region of the buffer space attached to a socket buffer.
 */
2796 2797
static int
__skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
2798
{
2799 2800
	int start = skb_headlen(skb);
	int i, copy = start - offset;
2801
	struct sk_buff *frag_iter;
2802 2803 2804 2805 2806
	int elt = 0;

	if (copy > 0) {
		if (copy > len)
			copy = len;
2807
		sg_set_buf(sg, skb->data + offset, copy);
2808 2809 2810 2811 2812 2813 2814
		elt++;
		if ((len -= copy) == 0)
			return elt;
		offset += copy;
	}

	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2815
		int end;
2816

2817
		WARN_ON(start > offset + len);
2818 2819

		end = start + skb_shinfo(skb)->frags[i].size;
2820 2821 2822 2823 2824
		if ((copy = end - offset) > 0) {
			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];

			if (copy > len)
				copy = len;
2825 2826
			sg_set_page(&sg[elt], frag->page, copy,
					frag->page_offset+offset-start);
2827 2828 2829 2830 2831
			elt++;
			if (!(len -= copy))
				return elt;
			offset += copy;
		}
2832
		start = end;
2833 2834
	}

2835 2836
	skb_walk_frags(skb, frag_iter) {
		int end;
2837

2838
		WARN_ON(start > offset + len);
2839

2840 2841 2842 2843 2844 2845 2846 2847 2848
		end = start + frag_iter->len;
		if ((copy = end - offset) > 0) {
			if (copy > len)
				copy = len;
			elt += __skb_to_sgvec(frag_iter, sg+elt, offset - start,
					      copy);
			if ((len -= copy) == 0)
				return elt;
			offset += copy;
2849
		}
2850
		start = end;
2851 2852 2853 2854 2855
	}
	BUG_ON(len);
	return elt;
}

2856 2857 2858 2859
int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
{
	int nsg = __skb_to_sgvec(skb, sg, offset, len);

J
Jens Axboe 已提交
2860
	sg_mark_end(&sg[nsg - 1]);
2861 2862 2863

	return nsg;
}
2864
EXPORT_SYMBOL_GPL(skb_to_sgvec);
2865

2866 2867 2868 2869 2870 2871 2872 2873 2874 2875 2876 2877 2878 2879 2880 2881 2882 2883 2884 2885 2886 2887 2888 2889 2890 2891 2892 2893 2894 2895 2896 2897
/**
 *	skb_cow_data - Check that a socket buffer's data buffers are writable
 *	@skb: The socket buffer to check.
 *	@tailbits: Amount of trailing space to be added
 *	@trailer: Returned pointer to the skb where the @tailbits space begins
 *
 *	Make sure that the data buffers attached to a socket buffer are
 *	writable. If they are not, private copies are made of the data buffers
 *	and the socket buffer is set to use these instead.
 *
 *	If @tailbits is given, make sure that there is space to write @tailbits
 *	bytes of data beyond current end of socket buffer.  @trailer will be
 *	set to point to the skb in which this space begins.
 *
 *	The number of scatterlist elements required to completely map the
 *	COW'd and extended socket buffer will be returned.
 */
int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
{
	int copyflag;
	int elt;
	struct sk_buff *skb1, **skb_p;

	/* If skb is cloned or its head is paged, reallocate
	 * head pulling out all the pages (pages are considered not writable
	 * at the moment even if they are anonymous).
	 */
	if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
	    __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL)
		return -ENOMEM;

	/* Easy case. Most of packets will go this way. */
2898
	if (!skb_has_frag_list(skb)) {
2899 2900 2901 2902 2903 2904 2905 2906 2907 2908 2909 2910 2911 2912 2913 2914 2915 2916 2917 2918 2919 2920 2921 2922 2923 2924 2925 2926 2927 2928 2929 2930 2931 2932
		/* A little of trouble, not enough of space for trailer.
		 * This should not happen, when stack is tuned to generate
		 * good frames. OK, on miss we reallocate and reserve even more
		 * space, 128 bytes is fair. */

		if (skb_tailroom(skb) < tailbits &&
		    pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
			return -ENOMEM;

		/* Voila! */
		*trailer = skb;
		return 1;
	}

	/* Misery. We are in troubles, going to mincer fragments... */

	elt = 1;
	skb_p = &skb_shinfo(skb)->frag_list;
	copyflag = 0;

	while ((skb1 = *skb_p) != NULL) {
		int ntail = 0;

		/* The fragment is partially pulled by someone,
		 * this can happen on input. Copy it and everything
		 * after it. */

		if (skb_shared(skb1))
			copyflag = 1;

		/* If the skb is the last, worry about trailer. */

		if (skb1->next == NULL && tailbits) {
			if (skb_shinfo(skb1)->nr_frags ||
2933
			    skb_has_frag_list(skb1) ||
2934 2935 2936 2937 2938 2939 2940 2941
			    skb_tailroom(skb1) < tailbits)
				ntail = tailbits + 128;
		}

		if (copyflag ||
		    skb_cloned(skb1) ||
		    ntail ||
		    skb_shinfo(skb1)->nr_frags ||
2942
		    skb_has_frag_list(skb1)) {
2943 2944 2945 2946 2947 2948 2949 2950 2951 2952 2953 2954 2955 2956 2957 2958 2959 2960 2961 2962 2963 2964 2965 2966 2967 2968 2969 2970 2971 2972 2973
			struct sk_buff *skb2;

			/* Fuck, we are miserable poor guys... */
			if (ntail == 0)
				skb2 = skb_copy(skb1, GFP_ATOMIC);
			else
				skb2 = skb_copy_expand(skb1,
						       skb_headroom(skb1),
						       ntail,
						       GFP_ATOMIC);
			if (unlikely(skb2 == NULL))
				return -ENOMEM;

			if (skb1->sk)
				skb_set_owner_w(skb2, skb1->sk);

			/* Looking around. Are we still alive?
			 * OK, link new skb, drop old one */

			skb2->next = skb1->next;
			*skb_p = skb2;
			kfree_skb(skb1);
			skb1 = skb2;
		}
		elt++;
		*trailer = skb1;
		skb_p = &skb1->next;
	}

	return elt;
}
2974
EXPORT_SYMBOL_GPL(skb_cow_data);
2975

2976 2977 2978 2979 2980 2981 2982 2983 2984 2985 2986 2987 2988 2989 2990 2991 2992 2993 2994 2995 2996 2997 2998 2999 3000 3001 3002 3003
static void sock_rmem_free(struct sk_buff *skb)
{
	struct sock *sk = skb->sk;

	atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
}

/*
 * Note: We dont mem charge error packets (no sk_forward_alloc changes)
 */
int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
{
	if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
	    (unsigned)sk->sk_rcvbuf)
		return -ENOMEM;

	skb_orphan(skb);
	skb->sk = sk;
	skb->destructor = sock_rmem_free;
	atomic_add(skb->truesize, &sk->sk_rmem_alloc);

	skb_queue_tail(&sk->sk_error_queue, skb);
	if (!sock_flag(sk, SOCK_DEAD))
		sk->sk_data_ready(sk, skb->len);
	return 0;
}
EXPORT_SYMBOL(sock_queue_err_skb);

3004 3005 3006 3007 3008 3009 3010 3011 3012 3013 3014 3015 3016 3017 3018 3019 3020 3021 3022 3023 3024
void skb_tstamp_tx(struct sk_buff *orig_skb,
		struct skb_shared_hwtstamps *hwtstamps)
{
	struct sock *sk = orig_skb->sk;
	struct sock_exterr_skb *serr;
	struct sk_buff *skb;
	int err;

	if (!sk)
		return;

	skb = skb_clone(orig_skb, GFP_ATOMIC);
	if (!skb)
		return;

	if (hwtstamps) {
		*skb_hwtstamps(skb) =
			*hwtstamps;
	} else {
		/*
		 * no hardware time stamps available,
3025
		 * so keep the shared tx_flags and only
3026 3027 3028 3029 3030 3031 3032 3033 3034
		 * store software time stamp
		 */
		skb->tstamp = ktime_get_real();
	}

	serr = SKB_EXT_ERR(skb);
	memset(serr, 0, sizeof(*serr));
	serr->ee.ee_errno = ENOMSG;
	serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
3035

3036
	err = sock_queue_err_skb(sk, skb);
3037

3038 3039 3040 3041 3042 3043
	if (err)
		kfree_skb(skb);
}
EXPORT_SYMBOL_GPL(skb_tstamp_tx);


3044 3045 3046 3047 3048 3049 3050 3051 3052 3053 3054 3055 3056 3057
/**
 * skb_partial_csum_set - set up and verify partial csum values for packet
 * @skb: the skb to set
 * @start: the number of bytes after skb->data to start checksumming.
 * @off: the offset from start to place the checksum.
 *
 * For untrusted partially-checksummed packets, we need to make sure the values
 * for skb->csum_start and skb->csum_offset are valid so we don't oops.
 *
 * This function checks and sets those values and skb->ip_summed: if this
 * returns false you should drop the packet.
 */
bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
{
3058 3059
	if (unlikely(start > skb_headlen(skb)) ||
	    unlikely((int)start + off > skb_headlen(skb) - 2)) {
3060 3061 3062
		if (net_ratelimit())
			printk(KERN_WARNING
			       "bad partial csum: csum=%u/%u len=%u\n",
3063
			       start, off, skb_headlen(skb));
3064 3065 3066 3067 3068 3069 3070
		return false;
	}
	skb->ip_summed = CHECKSUM_PARTIAL;
	skb->csum_start = skb_headroom(skb) + start;
	skb->csum_offset = off;
	return true;
}
3071
EXPORT_SYMBOL_GPL(skb_partial_csum_set);
3072

3073 3074 3075 3076 3077 3078 3079
void __skb_warn_lro_forwarding(const struct sk_buff *skb)
{
	if (net_ratelimit())
		pr_warning("%s: received packets cannot be forwarded"
			   " while LRO is enabled\n", skb->dev->name);
}
EXPORT_SYMBOL(__skb_warn_lro_forwarding);