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linux/net/core/skbuff.c

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/*
* Routines having to do with the 'struct sk_buff' memory handlers.
*
* Authors: Alan Cox <iiitac@pyr.swan.ac.uk>
* Florian La Roche <rzsfl@rz.uni-sb.de>
*
* Version: $Id: skbuff.c,v 1.90 2001/11/07 05:56:19 davem Exp $
*
* 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/config.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#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>
#include <linux/cache.h>
#include <linux/rtnetlink.h>
#include <linux/init.h>
#include <linux/highmem.h>
#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>
static kmem_cache_t *skbuff_head_cache;
/*
* 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.
*/
void skb_over_panic(struct sk_buff *skb, int sz, void *here)
{
printk(KERN_INFO "skput:over: %p:%d put:%d dev:%s",
here, skb->len, sz, skb->dev ? skb->dev->name : "<NULL>");
BUG();
}
/**
* skb_under_panic - private function
* @skb: buffer
* @sz: size
* @here: address
*
* Out of line support code for skb_push(). Not user callable.
*/
void skb_under_panic(struct sk_buff *skb, int sz, void *here)
{
printk(KERN_INFO "skput:under: %p:%d put:%d dev:%s",
here, skb->len, sz, skb->dev ? skb->dev->name : "<NULL>");
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.
*
*/
/**
* alloc_skb - allocate a network buffer
* @size: size to allocate
* @gfp_mask: allocation mask
*
* 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.
*/
struct sk_buff *alloc_skb(unsigned int size, int gfp_mask)
{
struct sk_buff *skb;
u8 *data;
/* Get the HEAD */
skb = kmem_cache_alloc(skbuff_head_cache,
gfp_mask & ~__GFP_DMA);
if (!skb)
goto out;
/* Get the DATA. Size must match skb_add_mtu(). */
size = SKB_DATA_ALIGN(size);
data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
if (!data)
goto nodata;
memset(skb, 0, offsetof(struct sk_buff, truesize));
skb->truesize = size + sizeof(struct sk_buff);
atomic_set(&skb->users, 1);
skb->head = data;
skb->data = data;
skb->tail = data;
skb->end = data + size;
atomic_set(&(skb_shinfo(skb)->dataref), 1);
skb_shinfo(skb)->nr_frags = 0;
skb_shinfo(skb)->tso_size = 0;
skb_shinfo(skb)->tso_segs = 0;
skb_shinfo(skb)->frag_list = NULL;
out:
return skb;
nodata:
kmem_cache_free(skbuff_head_cache, skb);
skb = NULL;
goto out;
}
/**
* alloc_skb_from_cache - allocate a network buffer
* @cp: kmem_cache from which to allocate the data area
* (object size must be big enough for @size bytes + skb overheads)
* @size: size to allocate
* @gfp_mask: allocation mask
*
* Allocate a new &sk_buff. The returned buffer has no headroom and
* 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.
*/
struct sk_buff *alloc_skb_from_cache(kmem_cache_t *cp,
unsigned int size, int gfp_mask)
{
struct sk_buff *skb;
u8 *data;
/* Get the HEAD */
skb = kmem_cache_alloc(skbuff_head_cache,
gfp_mask & ~__GFP_DMA);
if (!skb)
goto out;
/* Get the DATA. */
size = SKB_DATA_ALIGN(size);
data = kmem_cache_alloc(cp, gfp_mask);
if (!data)
goto nodata;
memset(skb, 0, offsetof(struct sk_buff, truesize));
skb->truesize = size + sizeof(struct sk_buff);
atomic_set(&skb->users, 1);
skb->head = data;
skb->data = data;
skb->tail = data;
skb->end = data + size;
atomic_set(&(skb_shinfo(skb)->dataref), 1);
skb_shinfo(skb)->nr_frags = 0;
skb_shinfo(skb)->tso_size = 0;
skb_shinfo(skb)->tso_segs = 0;
skb_shinfo(skb)->frag_list = NULL;
out:
return skb;
nodata:
kmem_cache_free(skbuff_head_cache, skb);
skb = NULL;
goto out;
}
static void skb_drop_fraglist(struct sk_buff *skb)
{
struct sk_buff *list = skb_shinfo(skb)->frag_list;
skb_shinfo(skb)->frag_list = NULL;
do {
struct sk_buff *this = list;
list = list->next;
kfree_skb(this);
} while (list);
}
static void skb_clone_fraglist(struct sk_buff *skb)
{
struct sk_buff *list;
for (list = skb_shinfo(skb)->frag_list; list; list = list->next)
skb_get(list);
}
void skb_release_data(struct sk_buff *skb)
{
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);
}
if (skb_shinfo(skb)->frag_list)
skb_drop_fraglist(skb);
kfree(skb->head);
}
}
/*
* Free an skbuff by memory without cleaning the state.
*/
void kfree_skbmem(struct sk_buff *skb)
{
skb_release_data(skb);
kmem_cache_free(skbuff_head_cache, 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
*/
void __kfree_skb(struct sk_buff *skb)
{
if (skb->list) {
printk(KERN_WARNING "Warning: kfree_skb passed an skb still "
"on a list (from %p).\n", NET_CALLER(skb));
BUG();
}
dst_release(skb->dst);
#ifdef CONFIG_XFRM
secpath_put(skb->sp);
#endif
if(skb->destructor) {
if (in_irq())
printk(KERN_WARNING "Warning: kfree_skb on "
"hard IRQ %p\n", NET_CALLER(skb));
skb->destructor(skb);
}
#ifdef CONFIG_NETFILTER
nf_conntrack_put(skb->nfct);
#ifdef CONFIG_BRIDGE_NETFILTER
nf_bridge_put(skb->nf_bridge);
#endif
#endif
/* XXX: IS this still necessary? - JHS */
#ifdef CONFIG_NET_SCHED
skb->tc_index = 0;
#ifdef CONFIG_NET_CLS_ACT
skb->tc_verd = 0;
skb->tc_classid = 0;
#endif
#endif
kfree_skbmem(skb);
}
/**
* 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, int gfp_mask)
{
struct sk_buff *n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
if (!n)
return NULL;
#define C(x) n->x = skb->x
n->next = n->prev = NULL;
n->list = NULL;
n->sk = NULL;
C(stamp);
C(dev);
C(real_dev);
C(h);
C(nh);
C(mac);
C(dst);
dst_clone(skb->dst);
C(sp);
#ifdef CONFIG_INET
secpath_get(skb->sp);
#endif
memcpy(n->cb, skb->cb, sizeof(skb->cb));
C(len);
C(data_len);
C(csum);
C(local_df);
n->cloned = 1;
n->nohdr = 0;
C(pkt_type);
C(ip_summed);
C(priority);
C(protocol);
C(security);
n->destructor = NULL;
#ifdef CONFIG_NETFILTER
C(nfmark);
C(nfcache);
C(nfct);
nf_conntrack_get(skb->nfct);
C(nfctinfo);
#ifdef CONFIG_NETFILTER_DEBUG
C(nf_debug);
#endif
#ifdef CONFIG_BRIDGE_NETFILTER
C(nf_bridge);
nf_bridge_get(skb->nf_bridge);
#endif
#endif /*CONFIG_NETFILTER*/
#if defined(CONFIG_HIPPI)
C(private);
#endif
#ifdef CONFIG_NET_SCHED
C(tc_index);
#ifdef CONFIG_NET_CLS_ACT
n->tc_verd = SET_TC_VERD(skb->tc_verd,0);
n->tc_verd = CLR_TC_OK2MUNGE(skb->tc_verd);
n->tc_verd = CLR_TC_MUNGED(skb->tc_verd);
C(input_dev);
C(tc_classid);
#endif
#endif
C(truesize);
atomic_set(&n->users, 1);
C(head);
C(data);
C(tail);
C(end);
atomic_inc(&(skb_shinfo(skb)->dataref));
skb->cloned = 1;
return n;
}
static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
{
/*
* Shift between the two data areas in bytes
*/
unsigned long offset = new->data - old->data;
new->list = NULL;
new->sk = NULL;
new->dev = old->dev;
new->real_dev = old->real_dev;
new->priority = old->priority;
new->protocol = old->protocol;
new->dst = dst_clone(old->dst);
#ifdef CONFIG_INET
new->sp = secpath_get(old->sp);
#endif
new->h.raw = old->h.raw + offset;
new->nh.raw = old->nh.raw + offset;
new->mac.raw = old->mac.raw + offset;
memcpy(new->cb, old->cb, sizeof(old->cb));
new->local_df = old->local_df;
new->pkt_type = old->pkt_type;
new->stamp = old->stamp;
new->destructor = NULL;
new->security = old->security;
#ifdef CONFIG_NETFILTER
new->nfmark = old->nfmark;
new->nfcache = old->nfcache;
new->nfct = old->nfct;
nf_conntrack_get(old->nfct);
new->nfctinfo = old->nfctinfo;
#ifdef CONFIG_NETFILTER_DEBUG
new->nf_debug = old->nf_debug;
#endif
#ifdef CONFIG_BRIDGE_NETFILTER
new->nf_bridge = old->nf_bridge;
nf_bridge_get(old->nf_bridge);
#endif
#endif
#ifdef CONFIG_NET_SCHED
#ifdef CONFIG_NET_CLS_ACT
new->tc_verd = old->tc_verd;
#endif
new->tc_index = old->tc_index;
#endif
atomic_set(&new->users, 1);
skb_shinfo(new)->tso_size = skb_shinfo(old)->tso_size;
skb_shinfo(new)->tso_segs = skb_shinfo(old)->tso_segs;
}
/**
* 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.
*/
struct sk_buff *skb_copy(const struct sk_buff *skb, int gfp_mask)
{
int headerlen = skb->data - skb->head;
/*
* Allocate the copy buffer
*/
struct sk_buff *n = alloc_skb(skb->end - skb->head + skb->data_len,
gfp_mask);
if (!n)
return NULL;
/* Set the data pointer */
skb_reserve(n, headerlen);
/* Set the tail pointer and length */
skb_put(n, skb->len);
n->csum = skb->csum;
n->ip_summed = skb->ip_summed;
if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
BUG();
copy_skb_header(n, skb);
return n;
}
/**
* 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.
*/
struct sk_buff *pskb_copy(struct sk_buff *skb, int gfp_mask)
{
/*
* Allocate the copy buffer
*/
struct sk_buff *n = alloc_skb(skb->end - skb->head, gfp_mask);
if (!n)
goto out;
/* Set the data pointer */
skb_reserve(n, skb->data - skb->head);
/* Set the tail pointer and length */
skb_put(n, skb_headlen(skb));
/* Copy the bytes */
memcpy(n->data, skb->data, n->len);
n->csum = skb->csum;
n->ip_summed = skb->ip_summed;
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;
}
if (skb_shinfo(skb)->frag_list) {
skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
skb_clone_fraglist(n);
}
copy_skb_header(n, skb);
out:
return n;
}
/**
* 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.
*/
int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, int gfp_mask)
{
int i;
u8 *data;
int size = nhead + (skb->end - skb->head) + ntail;
long off;
if (skb_shared(skb))
BUG();
size = SKB_DATA_ALIGN(size);
data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
if (!data)
goto nodata;
/* Copy only real data... and, alas, header. This should be
* optimized for the cases when header is void. */
memcpy(data + nhead, skb->head, skb->tail - skb->head);
memcpy(data + size, skb->end, sizeof(struct skb_shared_info));
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
get_page(skb_shinfo(skb)->frags[i].page);
if (skb_shinfo(skb)->frag_list)
skb_clone_fraglist(skb);
skb_release_data(skb);
off = (data + nhead) - skb->head;
skb->head = data;
skb->end = data + size;
skb->data += off;
skb->tail += off;
skb->mac.raw += off;
skb->h.raw += off;
skb->nh.raw += off;
skb->cloned = 0;
skb->nohdr = 0;
atomic_set(&skb_shinfo(skb)->dataref, 1);
return 0;
nodata:
return -ENOMEM;
}
/* 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;
}
/**
* 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.
*
* BUG ALERT: ip_summed is not copied. Why does this work? Is it used
* only by netfilter in the cases when checksum is recalculated? --ANK
*/
struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
int newheadroom, int newtailroom, int gfp_mask)
{
/*
* Allocate the copy buffer
*/
struct sk_buff *n = alloc_skb(newheadroom + skb->len + newtailroom,
gfp_mask);
int head_copy_len, head_copy_off;
if (!n)
return NULL;
skb_reserve(n, newheadroom);
/* Set the tail pointer and length */
skb_put(n, skb->len);
head_copy_len = skb_headroom(skb);
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);
return n;
}
/**
* 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.
*
* May return NULL in out of memory cases.
*/
struct sk_buff *skb_pad(struct sk_buff *skb, int pad)
{
struct sk_buff *nskb;
/* If the skbuff is non linear tailroom is always zero.. */
if (skb_tailroom(skb) >= pad) {
memset(skb->data+skb->len, 0, pad);
return skb;
}
nskb = skb_copy_expand(skb, skb_headroom(skb), skb_tailroom(skb) + pad, GFP_ATOMIC);
kfree_skb(skb);
if (nskb)
memset(nskb->data+nskb->len, 0, pad);
return nskb;
}
/* Trims skb to length len. It can change skb pointers, if "realloc" is 1.
* If realloc==0 and trimming is impossible without change of data,
* it is BUG().
*/
int ___pskb_trim(struct sk_buff *skb, unsigned int len, int realloc)
{
int offset = skb_headlen(skb);
int nfrags = skb_shinfo(skb)->nr_frags;
int i;
for (i = 0; i < nfrags; i++) {
int end = offset + skb_shinfo(skb)->frags[i].size;
if (end > len) {
if (skb_cloned(skb)) {
if (!realloc)
BUG();
if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
return -ENOMEM;
}
if (len <= offset) {
put_page(skb_shinfo(skb)->frags[i].page);
skb_shinfo(skb)->nr_frags--;
} else {
skb_shinfo(skb)->frags[i].size = len - offset;
}
}
offset = end;
}
if (offset < len) {
skb->data_len -= skb->len - len;
skb->len = len;
} else {
if (len <= skb_headlen(skb)) {
skb->len = len;
skb->data_len = 0;
skb->tail = skb->data + len;
if (skb_shinfo(skb)->frag_list && !skb_cloned(skb))
skb_drop_fraglist(skb);
} else {
skb->data_len -= skb->len - len;
skb->len = len;
}
}
return 0;
}
/**
* __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.
*/
int i, k, eat = (skb->tail + delta) - skb->end;
if (eat > 0 || skb_cloned(skb)) {
if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
GFP_ATOMIC))
return NULL;
}
if (skb_copy_bits(skb, skb_headlen(skb), skb->tail, delta))
BUG();
/* Optimization: no fragments, no reasons to preestimate
* size of pulled pages. Superb.
*/
if (!skb_shinfo(skb)->frag_list)
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 {
if (!list)
BUG();
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)) {
if (clone)
kfree_skb(clone);
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;
return skb->tail;
}
/* Copy some data bits from skb to kernel buffer. */
int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
{
int i, copy;
int start = skb_headlen(skb);
if (offset > (int)skb->len - len)
goto fault;
/* Copy header. */
if ((copy = start - offset) > 0) {
if (copy > len)
copy = len;
memcpy(to, skb->data + offset, copy);
if ((len -= copy) == 0)
return 0;
offset += copy;
to += copy;
}
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
int end;
BUG_TRAP(start <= offset + len);
end = start + skb_shinfo(skb)->frags[i].size;
if ((copy = end - offset) > 0) {
u8 *vaddr;
if (copy > len)
copy = len;
vaddr = kmap_skb_frag(&skb_shinfo(skb)->frags[i]);
memcpy(to,
vaddr + skb_shinfo(skb)->frags[i].page_offset+
offset - start, copy);
kunmap_skb_frag(vaddr);
if ((len -= copy) == 0)
return 0;
offset += copy;
to += copy;
}
start = end;
}
if (skb_shinfo(skb)->frag_list) {
struct sk_buff *list = skb_shinfo(skb)->frag_list;
for (; list; list = list->next) {
int end;
BUG_TRAP(start <= offset + len);
end = start + list->len;
if ((copy = end - offset) > 0) {
if (copy > len)
copy = len;
if (skb_copy_bits(list, offset - start,
to, copy))
goto fault;
if ((len -= copy) == 0)
return 0;
offset += copy;
to += copy;
}
start = end;
}
}
if (!len)
return 0;
fault:
return -EFAULT;
}
/* Checksum skb data. */
unsigned int skb_checksum(const struct sk_buff *skb, int offset,
int len, unsigned int csum)
{
int start = skb_headlen(skb);
int i, copy = start - offset;
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++) {
int end;
BUG_TRAP(start <= offset + len);
end = start + skb_shinfo(skb)->frags[i].size;
if ((copy = end - offset) > 0) {
unsigned int csum2;
u8 *vaddr;
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
if (copy > len)
copy = len;
vaddr = kmap_skb_frag(frag);
csum2 = csum_partial(vaddr + frag->page_offset +
offset - start, copy, 0);
kunmap_skb_frag(vaddr);
csum = csum_block_add(csum, csum2, pos);
if (!(len -= copy))
return csum;
offset += copy;
pos += copy;
}
start = end;
}
if (skb_shinfo(skb)->frag_list) {
struct sk_buff *list = skb_shinfo(skb)->frag_list;
for (; list; list = list->next) {
int end;
BUG_TRAP(start <= offset + len);
end = start + list->len;
if ((copy = end - offset) > 0) {
unsigned int csum2;
if (copy > len)
copy = len;
csum2 = skb_checksum(list, offset - start,
copy, 0);
csum = csum_block_add(csum, csum2, pos);
if ((len -= copy) == 0)
return csum;
offset += copy;
pos += copy;
}
start = end;
}
}
if (len)
BUG();
return csum;
}
/* Both of above in one bottle. */
unsigned int skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
u8 *to, int len, unsigned int csum)
{
int start = skb_headlen(skb);
int i, copy = start - offset;
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++) {
int end;
BUG_TRAP(start <= offset + len);
end = start + skb_shinfo(skb)->frags[i].size;
if ((copy = end - offset) > 0) {
unsigned int csum2;
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 +
frag->page_offset +
offset - start, to,
copy, 0);
kunmap_skb_frag(vaddr);
csum = csum_block_add(csum, csum2, pos);
if (!(len -= copy))
return csum;
offset += copy;
to += copy;
pos += copy;
}
start = end;
}
if (skb_shinfo(skb)->frag_list) {
struct sk_buff *list = skb_shinfo(skb)->frag_list;
for (; list; list = list->next) {
unsigned int csum2;
int end;
BUG_TRAP(start <= offset + len);
end = start + list->len;
if ((copy = end - offset) > 0) {
if (copy > len)
copy = len;
csum2 = skb_copy_and_csum_bits(list,
offset - start,
to, copy, 0);
csum = csum_block_add(csum, csum2, pos);
if ((len -= copy) == 0)
return csum;
offset += copy;
to += copy;
pos += copy;
}
start = end;
}
}
if (len)
BUG();
return csum;
}
void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
{
unsigned int csum;
long csstart;
if (skb->ip_summed == CHECKSUM_HW)
csstart = skb->h.raw - skb->data;
else
csstart = skb_headlen(skb);
if (csstart > skb_headlen(skb))
BUG();
memcpy(to, skb->data, csstart);
csum = 0;
if (csstart != skb->len)
csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
skb->len - csstart, 0);
if (skb->ip_summed == CHECKSUM_HW) {
long csstuff = csstart + skb->csum;
*((unsigned short *)(to + csstuff)) = csum_fold(csum);
}
}
/**
* 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;
}
/**
* 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;
}
/**
* 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);
}
/**
* 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);
}
/**
* 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);
}
/**
* skb_unlink - remove a buffer from a list
* @skb: buffer to remove
*
* 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
*
* Works even without knowing the list it is sitting on, which can be
* handy at times. It also means that THE LIST MUST EXIST when you
* unlink. Thus a list must have its contents unlinked before it is
* destroyed.
*/
void skb_unlink(struct sk_buff *skb)
{
struct sk_buff_head *list = skb->list;
if (list) {
unsigned long flags;
spin_lock_irqsave(&list->lock, flags);
if (skb->list == list)
__skb_unlink(skb, skb->list);
spin_unlock_irqrestore(&list->lock, flags);
}
}
/**
* skb_append - append a buffer
* @old: buffer to insert after
* @newsk: buffer to insert
*
* 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.
*/
void skb_append(struct sk_buff *old, struct sk_buff *newsk)
{
unsigned long flags;
spin_lock_irqsave(&old->list->lock, flags);
__skb_append(old, newsk);
spin_unlock_irqrestore(&old->list->lock, flags);
}
/**
* skb_insert - insert a buffer
* @old: buffer to insert before
* @newsk: buffer to insert
*
* 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
* A buffer cannot be placed on two lists at the same time.
*/
void skb_insert(struct sk_buff *old, struct sk_buff *newsk)
{
unsigned long flags;
spin_lock_irqsave(&old->list->lock, flags);
__skb_insert(newsk, old->prev, old, old->list);
spin_unlock_irqrestore(&old->list->lock, flags);
}
#if 0
/*
* Tune the memory allocator for a new MTU size.
*/
void skb_add_mtu(int mtu)
{
/* Must match allocation in alloc_skb */
mtu = SKB_DATA_ALIGN(mtu) + sizeof(struct skb_shared_info);
kmem_add_cache_size(mtu);
}
#endif
static inline void skb_split_inside_header(struct sk_buff *skb,
struct sk_buff* skb1,
const u32 len, const int pos)
{
int i;
memcpy(skb_put(skb1, pos - len), skb->data + len, pos - len);
/* 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;
skb->tail = skb->data + len;
}
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);
}
void __init skb_init(void)
{
skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
sizeof(struct sk_buff),
0,
SLAB_HWCACHE_ALIGN,
NULL, NULL);
if (!skbuff_head_cache)
panic("cannot create skbuff cache");
}
EXPORT_SYMBOL(___pskb_trim);
EXPORT_SYMBOL(__kfree_skb);
EXPORT_SYMBOL(__pskb_pull_tail);
EXPORT_SYMBOL(alloc_skb);
EXPORT_SYMBOL(pskb_copy);
EXPORT_SYMBOL(pskb_expand_head);
EXPORT_SYMBOL(skb_checksum);
EXPORT_SYMBOL(skb_clone);
EXPORT_SYMBOL(skb_clone_fraglist);
EXPORT_SYMBOL(skb_copy);
EXPORT_SYMBOL(skb_copy_and_csum_bits);
EXPORT_SYMBOL(skb_copy_and_csum_dev);
EXPORT_SYMBOL(skb_copy_bits);
EXPORT_SYMBOL(skb_copy_expand);
EXPORT_SYMBOL(skb_over_panic);
EXPORT_SYMBOL(skb_pad);
EXPORT_SYMBOL(skb_realloc_headroom);
EXPORT_SYMBOL(skb_under_panic);
EXPORT_SYMBOL(skb_dequeue);
EXPORT_SYMBOL(skb_dequeue_tail);
EXPORT_SYMBOL(skb_insert);
EXPORT_SYMBOL(skb_queue_purge);
EXPORT_SYMBOL(skb_queue_head);
EXPORT_SYMBOL(skb_queue_tail);
EXPORT_SYMBOL(skb_unlink);
EXPORT_SYMBOL(skb_append);
EXPORT_SYMBOL(skb_split);
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