blob: 946de0e24c876bbbe63de71b5c7cef91cb967708 [file] [log] [blame]
/*
* Routines having to do with the 'struct sk_buff' memory handlers.
*
* Authors: Alan Cox <alan@lxorguk.ukuu.org.uk>
* 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
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/slab.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/sctp.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/splice.h>
#include <linux/cache.h>
#include <linux/rtnetlink.h>
#include <linux/init.h>
#include <linux/scatterlist.h>
#include <linux/errqueue.h>
#include <linux/prefetch.h>
#include <linux/if_vlan.h>
#include <net/protocol.h>
#include <net/dst.h>
#include <net/sock.h>
#include <net/checksum.h>
#include <net/ip6_checksum.h>
#include <net/xfrm.h>
#include <linux/uaccess.h>
#include <trace/events/skb.h>
#include <linux/highmem.h>
#include <linux/capability.h>
#include <linux/user_namespace.h>
struct kmem_cache *skbuff_head_cache __ro_after_init;
static struct kmem_cache *skbuff_fclone_cache __ro_after_init;
int sysctl_max_skb_frags __read_mostly = MAX_SKB_FRAGS;
EXPORT_SYMBOL(sysctl_max_skb_frags);
/**
* skb_panic - private function for out-of-line support
* @skb: buffer
* @sz: size
* @addr: address
* @msg: skb_over_panic or skb_under_panic
*
* Out-of-line support for skb_put() and skb_push().
* Called via the wrapper skb_over_panic() or skb_under_panic().
* Keep out of line to prevent kernel bloat.
* __builtin_return_address is not used because it is not always reliable.
*/
static void skb_panic(struct sk_buff *skb, unsigned int sz, void *addr,
const char msg[])
{
pr_emerg("%s: text:%p len:%d put:%d head:%p data:%p tail:%#lx end:%#lx dev:%s\n",
msg, addr, skb->len, sz, skb->head, skb->data,
(unsigned long)skb->tail, (unsigned long)skb->end,
skb->dev ? skb->dev->name : "<NULL>");
BUG();
}
static void skb_over_panic(struct sk_buff *skb, unsigned int sz, void *addr)
{
skb_panic(skb, sz, addr, __func__);
}
static void skb_under_panic(struct sk_buff *skb, unsigned int sz, void *addr)
{
skb_panic(skb, sz, addr, __func__);
}
/*
* kmalloc_reserve is a wrapper around kmalloc_node_track_caller that tells
* the caller if emergency pfmemalloc reserves are being used. If it is and
* the socket is later found to be SOCK_MEMALLOC then PFMEMALLOC reserves
* may be used. Otherwise, the packet data may be discarded until enough
* memory is free
*/
#define kmalloc_reserve(size, gfp, node, pfmemalloc) \
__kmalloc_reserve(size, gfp, node, _RET_IP_, pfmemalloc)
static void *__kmalloc_reserve(size_t size, gfp_t flags, int node,
unsigned long ip, bool *pfmemalloc)
{
void *obj;
bool ret_pfmemalloc = false;
/*
* Try a regular allocation, when that fails and we're not entitled
* to the reserves, fail.
*/
obj = kmalloc_node_track_caller(size,
flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
node);
if (obj || !(gfp_pfmemalloc_allowed(flags)))
goto out;
/* Try again but now we are using pfmemalloc reserves */
ret_pfmemalloc = true;
obj = kmalloc_node_track_caller(size, flags, node);
out:
if (pfmemalloc)
*pfmemalloc = ret_pfmemalloc;
return obj;
}
/* 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
* @flags: If SKB_ALLOC_FCLONE is set, allocate from fclone cache
* instead of head cache and allocate a cloned (child) skb.
* If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for
* allocations in case the data is required for writeback
* @node: numa node to allocate memory on
*
* Allocate a new &sk_buff. The returned buffer has no headroom and a
* tail room of at least 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, gfp_t gfp_mask,
int flags, int node)
{
struct kmem_cache *cache;
struct skb_shared_info *shinfo;
struct sk_buff *skb;
u8 *data;
bool pfmemalloc;
cache = (flags & SKB_ALLOC_FCLONE)
? skbuff_fclone_cache : skbuff_head_cache;
if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX))
gfp_mask |= __GFP_MEMALLOC;
/* Get the HEAD */
skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
if (!skb)
goto out;
prefetchw(skb);
/* We do our best to align skb_shared_info on a separate cache
* line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
* aligned memory blocks, unless SLUB/SLAB debug is enabled.
* Both skb->head and skb_shared_info are cache line aligned.
*/
size = SKB_DATA_ALIGN(size);
size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
data = kmalloc_reserve(size, gfp_mask, node, &pfmemalloc);
if (!data)
goto nodata;
/* kmalloc(size) might give us more room than requested.
* Put skb_shared_info exactly at the end of allocated zone,
* to allow max possible filling before reallocation.
*/
size = SKB_WITH_OVERHEAD(ksize(data));
prefetchw(data + size);
/*
* 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!
*/
memset(skb, 0, offsetof(struct sk_buff, tail));
/* Account for allocated memory : skb + skb->head */
skb->truesize = SKB_TRUESIZE(size);
skb->pfmemalloc = pfmemalloc;
refcount_set(&skb->users, 1);
skb->head = data;
skb->data = data;
skb_reset_tail_pointer(skb);
skb->end = skb->tail + size;
skb->mac_header = (typeof(skb->mac_header))~0U;
skb->transport_header = (typeof(skb->transport_header))~0U;
/* make sure we initialize shinfo sequentially */
shinfo = skb_shinfo(skb);
memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
atomic_set(&shinfo->dataref, 1);
if (flags & SKB_ALLOC_FCLONE) {
struct sk_buff_fclones *fclones;
fclones = container_of(skb, struct sk_buff_fclones, skb1);
skb->fclone = SKB_FCLONE_ORIG;
refcount_set(&fclones->fclone_ref, 1);
fclones->skb2.fclone = SKB_FCLONE_CLONE;
}
out:
return skb;
nodata:
kmem_cache_free(cache, skb);
skb = NULL;
goto out;
}
EXPORT_SYMBOL(__alloc_skb);
/**
* __build_skb - build a network buffer
* @data: data buffer provided by caller
* @frag_size: size of data, or 0 if head was kmalloced
*
* Allocate a new &sk_buff. Caller provides space holding head and
* skb_shared_info. @data must have been allocated by kmalloc() only if
* @frag_size is 0, otherwise data should come from the page allocator
* or vmalloc()
* The return is the new skb buffer.
* On a failure the return is %NULL, and @data is not freed.
* Notes :
* Before IO, driver allocates only data buffer where NIC put incoming frame
* Driver should add room at head (NET_SKB_PAD) and
* MUST add room at tail (SKB_DATA_ALIGN(skb_shared_info))
* After IO, driver calls build_skb(), to allocate sk_buff and populate it
* before giving packet to stack.
* RX rings only contains data buffers, not full skbs.
*/
struct sk_buff *__build_skb(void *data, unsigned int frag_size)
{
struct skb_shared_info *shinfo;
struct sk_buff *skb;
unsigned int size = frag_size ? : ksize(data);
skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
if (!skb)
return NULL;
size -= SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
memset(skb, 0, offsetof(struct sk_buff, tail));
skb->truesize = SKB_TRUESIZE(size);
refcount_set(&skb->users, 1);
skb->head = data;
skb->data = data;
skb_reset_tail_pointer(skb);
skb->end = skb->tail + size;
skb->mac_header = (typeof(skb->mac_header))~0U;
skb->transport_header = (typeof(skb->transport_header))~0U;
/* make sure we initialize shinfo sequentially */
shinfo = skb_shinfo(skb);
memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
atomic_set(&shinfo->dataref, 1);
return skb;
}
/* build_skb() is wrapper over __build_skb(), that specifically
* takes care of skb->head and skb->pfmemalloc
* This means that if @frag_size is not zero, then @data must be backed
* by a page fragment, not kmalloc() or vmalloc()
*/
struct sk_buff *build_skb(void *data, unsigned int frag_size)
{
struct sk_buff *skb = __build_skb(data, frag_size);
if (skb && frag_size) {
skb->head_frag = 1;
if (page_is_pfmemalloc(virt_to_head_page(data)))
skb->pfmemalloc = 1;
}
return skb;
}
EXPORT_SYMBOL(build_skb);
#define NAPI_SKB_CACHE_SIZE 64
struct napi_alloc_cache {
struct page_frag_cache page;
unsigned int skb_count;
void *skb_cache[NAPI_SKB_CACHE_SIZE];
};
static DEFINE_PER_CPU(struct page_frag_cache, netdev_alloc_cache);
static DEFINE_PER_CPU(struct napi_alloc_cache, napi_alloc_cache);
static void *__netdev_alloc_frag(unsigned int fragsz, gfp_t gfp_mask)
{
struct page_frag_cache *nc;
unsigned long flags;
void *data;
local_irq_save(flags);
nc = this_cpu_ptr(&netdev_alloc_cache);
data = page_frag_alloc(nc, fragsz, gfp_mask);
local_irq_restore(flags);
return data;
}
/**
* netdev_alloc_frag - allocate a page fragment
* @fragsz: fragment size
*
* Allocates a frag from a page for receive buffer.
* Uses GFP_ATOMIC allocations.
*/
void *netdev_alloc_frag(unsigned int fragsz)
{
return __netdev_alloc_frag(fragsz, GFP_ATOMIC);
}
EXPORT_SYMBOL(netdev_alloc_frag);
static void *__napi_alloc_frag(unsigned int fragsz, gfp_t gfp_mask)
{
struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
return page_frag_alloc(&nc->page, fragsz, gfp_mask);
}
void *napi_alloc_frag(unsigned int fragsz)
{
return __napi_alloc_frag(fragsz, GFP_ATOMIC);
}
EXPORT_SYMBOL(napi_alloc_frag);
/**
* __netdev_alloc_skb - allocate an skbuff for rx on a specific device
* @dev: network device to receive on
* @len: 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 NET_SKB_PAD 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 len,
gfp_t gfp_mask)
{
struct page_frag_cache *nc;
unsigned long flags;
struct sk_buff *skb;
bool pfmemalloc;
void *data;
len += NET_SKB_PAD;
if ((len > SKB_WITH_OVERHEAD(PAGE_SIZE)) ||
(gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX, NUMA_NO_NODE);
if (!skb)
goto skb_fail;
goto skb_success;
}
len += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
len = SKB_DATA_ALIGN(len);
if (sk_memalloc_socks())
gfp_mask |= __GFP_MEMALLOC;
local_irq_save(flags);
nc = this_cpu_ptr(&netdev_alloc_cache);
data = page_frag_alloc(nc, len, gfp_mask);
pfmemalloc = nc->pfmemalloc;
local_irq_restore(flags);
if (unlikely(!data))
return NULL;
skb = __build_skb(data, len);
if (unlikely(!skb)) {
skb_free_frag(data);
return NULL;
}
/* use OR instead of assignment to avoid clearing of bits in mask */
if (pfmemalloc)
skb->pfmemalloc = 1;
skb->head_frag = 1;
skb_success:
skb_reserve(skb, NET_SKB_PAD);
skb->dev = dev;
skb_fail:
return skb;
}
EXPORT_SYMBOL(__netdev_alloc_skb);
/**
* __napi_alloc_skb - allocate skbuff for rx in a specific NAPI instance
* @napi: napi instance this buffer was allocated for
* @len: length to allocate
* @gfp_mask: get_free_pages mask, passed to alloc_skb and alloc_pages
*
* Allocate a new sk_buff for use in NAPI receive. This buffer will
* attempt to allocate the head from a special reserved region used
* only for NAPI Rx allocation. By doing this we can save several
* CPU cycles by avoiding having to disable and re-enable IRQs.
*
* %NULL is returned if there is no free memory.
*/
struct sk_buff *__napi_alloc_skb(struct napi_struct *napi, unsigned int len,
gfp_t gfp_mask)
{
struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
struct sk_buff *skb;
void *data;
len += NET_SKB_PAD + NET_IP_ALIGN;
if ((len > SKB_WITH_OVERHEAD(PAGE_SIZE)) ||
(gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX, NUMA_NO_NODE);
if (!skb)
goto skb_fail;
goto skb_success;
}
len += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
len = SKB_DATA_ALIGN(len);
if (sk_memalloc_socks())
gfp_mask |= __GFP_MEMALLOC;
data = page_frag_alloc(&nc->page, len, gfp_mask);
if (unlikely(!data))
return NULL;
skb = __build_skb(data, len);
if (unlikely(!skb)) {
skb_free_frag(data);
return NULL;
}
/* use OR instead of assignment to avoid clearing of bits in mask */
if (nc->page.pfmemalloc)
skb->pfmemalloc = 1;
skb->head_frag = 1;
skb_success:
skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
skb->dev = napi->dev;
skb_fail:
return skb;
}
EXPORT_SYMBOL(__napi_alloc_skb);
void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
int size, unsigned int truesize)
{
skb_fill_page_desc(skb, i, page, off, size);
skb->len += size;
skb->data_len += size;
skb->truesize += truesize;
}
EXPORT_SYMBOL(skb_add_rx_frag);
void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
unsigned int truesize)
{
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
skb_frag_size_add(frag, size);
skb->len += size;
skb->data_len += size;
skb->truesize += truesize;
}
EXPORT_SYMBOL(skb_coalesce_rx_frag);
static void skb_drop_list(struct sk_buff **listp)
{
kfree_skb_list(*listp);
*listp = NULL;
}
static inline void skb_drop_fraglist(struct sk_buff *skb)
{
skb_drop_list(&skb_shinfo(skb)->frag_list);
}
static void skb_clone_fraglist(struct sk_buff *skb)
{
struct sk_buff *list;
skb_walk_frags(skb, list)
skb_get(list);
}
static void skb_free_head(struct sk_buff *skb)
{
unsigned char *head = skb->head;
if (skb->head_frag)
skb_free_frag(head);
else
kfree(head);
}
static void skb_release_data(struct sk_buff *skb)
{
struct skb_shared_info *shinfo = skb_shinfo(skb);
int i;
if (skb->cloned &&
atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
&shinfo->dataref))
return;
for (i = 0; i < shinfo->nr_frags; i++)
__skb_frag_unref(&shinfo->frags[i]);
if (shinfo->frag_list)
kfree_skb_list(shinfo->frag_list);
skb_zcopy_clear(skb, true);
skb_free_head(skb);
}
/*
* Free an skbuff by memory without cleaning the state.
*/
static void kfree_skbmem(struct sk_buff *skb)
{
struct sk_buff_fclones *fclones;
switch (skb->fclone) {
case SKB_FCLONE_UNAVAILABLE:
kmem_cache_free(skbuff_head_cache, skb);
return;
case SKB_FCLONE_ORIG:
fclones = container_of(skb, struct sk_buff_fclones, skb1);
/* We usually free the clone (TX completion) before original skb
* This test would have no chance to be true for the clone,
* while here, branch prediction will be good.
*/
if (refcount_read(&fclones->fclone_ref) == 1)
goto fastpath;
break;
default: /* SKB_FCLONE_CLONE */
fclones = container_of(skb, struct sk_buff_fclones, skb2);
break;
}
if (!refcount_dec_and_test(&fclones->fclone_ref))
return;
fastpath:
kmem_cache_free(skbuff_fclone_cache, fclones);
}
void skb_release_head_state(struct sk_buff *skb)
{
skb_dst_drop(skb);
secpath_reset(skb);
if (skb->destructor) {
WARN_ON(in_irq());
skb->destructor(skb);
}
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
nf_conntrack_put(skb_nfct(skb));
#endif
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
nf_bridge_put(skb->nf_bridge);
#endif
}
/* Free everything but the sk_buff shell. */
static void skb_release_all(struct sk_buff *skb)
{
skb_release_head_state(skb);
if (likely(skb->head))
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
*/
void __kfree_skb(struct sk_buff *skb)
{
skb_release_all(skb);
kfree_skbmem(skb);
}
EXPORT_SYMBOL(__kfree_skb);
/**
* 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 (!skb_unref(skb))
return;
trace_kfree_skb(skb, __builtin_return_address(0));
__kfree_skb(skb);
}
EXPORT_SYMBOL(kfree_skb);
void kfree_skb_list(struct sk_buff *segs)
{
while (segs) {
struct sk_buff *next = segs->next;
kfree_skb(segs);
segs = next;
}
}
EXPORT_SYMBOL(kfree_skb_list);
/**
* skb_tx_error - report an sk_buff xmit error
* @skb: buffer that triggered an error
*
* Report xmit error if a device callback is tracking this skb.
* skb must be freed afterwards.
*/
void skb_tx_error(struct sk_buff *skb)
{
skb_zcopy_clear(skb, true);
}
EXPORT_SYMBOL(skb_tx_error);
/**
* 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 (!skb_unref(skb))
return;
trace_consume_skb(skb);
__kfree_skb(skb);
}
EXPORT_SYMBOL(consume_skb);
/**
* consume_stateless_skb - free an skbuff, assuming it is stateless
* @skb: buffer to free
*
* Alike consume_skb(), but this variant assumes that this is the last
* skb reference and all the head states have been already dropped
*/
void __consume_stateless_skb(struct sk_buff *skb)
{
trace_consume_skb(skb);
skb_release_data(skb);
kfree_skbmem(skb);
}
void __kfree_skb_flush(void)
{
struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
/* flush skb_cache if containing objects */
if (nc->skb_count) {
kmem_cache_free_bulk(skbuff_head_cache, nc->skb_count,
nc->skb_cache);
nc->skb_count = 0;
}
}
static inline void _kfree_skb_defer(struct sk_buff *skb)
{
struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
/* drop skb->head and call any destructors for packet */
skb_release_all(skb);
/* record skb to CPU local list */
nc->skb_cache[nc->skb_count++] = skb;
#ifdef CONFIG_SLUB
/* SLUB writes into objects when freeing */
prefetchw(skb);
#endif
/* flush skb_cache if it is filled */
if (unlikely(nc->skb_count == NAPI_SKB_CACHE_SIZE)) {
kmem_cache_free_bulk(skbuff_head_cache, NAPI_SKB_CACHE_SIZE,
nc->skb_cache);
nc->skb_count = 0;
}
}
void __kfree_skb_defer(struct sk_buff *skb)
{
_kfree_skb_defer(skb);
}
void napi_consume_skb(struct sk_buff *skb, int budget)
{
if (unlikely(!skb))
return;
/* Zero budget indicate non-NAPI context called us, like netpoll */
if (unlikely(!budget)) {
dev_consume_skb_any(skb);
return;
}
if (!skb_unref(skb))
return;
/* if reaching here SKB is ready to free */
trace_consume_skb(skb);
/* if SKB is a clone, don't handle this case */
if (skb->fclone != SKB_FCLONE_UNAVAILABLE) {
__kfree_skb(skb);
return;
}
_kfree_skb_defer(skb);
}
EXPORT_SYMBOL(napi_consume_skb);
/* Make sure a field is enclosed inside headers_start/headers_end section */
#define CHECK_SKB_FIELD(field) \
BUILD_BUG_ON(offsetof(struct sk_buff, field) < \
offsetof(struct sk_buff, headers_start)); \
BUILD_BUG_ON(offsetof(struct sk_buff, field) > \
offsetof(struct sk_buff, headers_end)); \
static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
{
new->tstamp = old->tstamp;
/* We do not copy old->sk */
new->dev = old->dev;
memcpy(new->cb, old->cb, sizeof(old->cb));
skb_dst_copy(new, old);
#ifdef CONFIG_XFRM
new->sp = secpath_get(old->sp);
#endif
__nf_copy(new, old, false);
/* Note : this field could be in headers_start/headers_end section
* It is not yet because we do not want to have a 16 bit hole
*/
new->queue_mapping = old->queue_mapping;
memcpy(&new->headers_start, &old->headers_start,
offsetof(struct sk_buff, headers_end) -
offsetof(struct sk_buff, headers_start));
CHECK_SKB_FIELD(protocol);
CHECK_SKB_FIELD(csum);
CHECK_SKB_FIELD(hash);
CHECK_SKB_FIELD(priority);
CHECK_SKB_FIELD(skb_iif);
CHECK_SKB_FIELD(vlan_proto);
CHECK_SKB_FIELD(vlan_tci);
CHECK_SKB_FIELD(transport_header);
CHECK_SKB_FIELD(network_header);
CHECK_SKB_FIELD(mac_header);
CHECK_SKB_FIELD(inner_protocol);
CHECK_SKB_FIELD(inner_transport_header);
CHECK_SKB_FIELD(inner_network_header);
CHECK_SKB_FIELD(inner_mac_header);
CHECK_SKB_FIELD(mark);
#ifdef CONFIG_NETWORK_SECMARK
CHECK_SKB_FIELD(secmark);
#endif
#ifdef CONFIG_NET_RX_BUSY_POLL
CHECK_SKB_FIELD(napi_id);
#endif
#ifdef CONFIG_XPS
CHECK_SKB_FIELD(sender_cpu);
#endif
#ifdef CONFIG_NET_SCHED
CHECK_SKB_FIELD(tc_index);
#endif
}
/*
* You should not add any new code to this function. Add it to
* __copy_skb_header above instead.
*/
static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
{
#define C(x) n->x = skb->x
n->next = n->prev = NULL;
n->sk = NULL;
__copy_skb_header(n, skb);
C(len);
C(data_len);
C(mac_len);
n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
n->cloned = 1;
n->nohdr = 0;
n->peeked = 0;
C(pfmemalloc);
n->destructor = NULL;
C(tail);
C(end);
C(head);
C(head_frag);
C(data);
C(truesize);
refcount_set(&n->users, 1);
atomic_inc(&(skb_shinfo(skb)->dataref));
skb->cloned = 1;
return n;
#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)
{
skb_release_all(dst);
return __skb_clone(dst, src);
}
EXPORT_SYMBOL_GPL(skb_morph);
int mm_account_pinned_pages(struct mmpin *mmp, size_t size)
{
unsigned long max_pg, num_pg, new_pg, old_pg;
struct user_struct *user;
if (capable(CAP_IPC_LOCK) || !size)
return 0;
num_pg = (size >> PAGE_SHIFT) + 2; /* worst case */
max_pg = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
user = mmp->user ? : current_user();
do {
old_pg = atomic_long_read(&user->locked_vm);
new_pg = old_pg + num_pg;
if (new_pg > max_pg)
return -ENOBUFS;
} while (atomic_long_cmpxchg(&user->locked_vm, old_pg, new_pg) !=
old_pg);
if (!mmp->user) {
mmp->user = get_uid(user);
mmp->num_pg = num_pg;
} else {
mmp->num_pg += num_pg;
}
return 0;
}
EXPORT_SYMBOL_GPL(mm_account_pinned_pages);
void mm_unaccount_pinned_pages(struct mmpin *mmp)
{
if (mmp->user) {
atomic_long_sub(mmp->num_pg, &mmp->user->locked_vm);
free_uid(mmp->user);
}
}
EXPORT_SYMBOL_GPL(mm_unaccount_pinned_pages);
struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size)
{
struct ubuf_info *uarg;
struct sk_buff *skb;
WARN_ON_ONCE(!in_task());
skb = sock_omalloc(sk, 0, GFP_KERNEL);
if (!skb)
return NULL;
BUILD_BUG_ON(sizeof(*uarg) > sizeof(skb->cb));
uarg = (void *)skb->cb;
uarg->mmp.user = NULL;
if (mm_account_pinned_pages(&uarg->mmp, size)) {
kfree_skb(skb);
return NULL;
}
uarg->callback = sock_zerocopy_callback;
uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
uarg->len = 1;
uarg->bytelen = size;
uarg->zerocopy = 1;
refcount_set(&uarg->refcnt, 1);
sock_hold(sk);
return uarg;
}
EXPORT_SYMBOL_GPL(sock_zerocopy_alloc);
static inline struct sk_buff *skb_from_uarg(struct ubuf_info *uarg)
{
return container_of((void *)uarg, struct sk_buff, cb);
}
struct ubuf_info *sock_zerocopy_realloc(struct sock *sk, size_t size,
struct ubuf_info *uarg)
{
if (uarg) {
const u32 byte_limit = 1 << 19; /* limit to a few TSO */
u32 bytelen, next;
/* realloc only when socket is locked (TCP, UDP cork),
* so uarg->len and sk_zckey access is serialized
*/
if (!sock_owned_by_user(sk)) {
WARN_ON_ONCE(1);
return NULL;
}
bytelen = uarg->bytelen + size;
if (uarg->len == USHRT_MAX - 1 || bytelen > byte_limit) {
/* TCP can create new skb to attach new uarg */
if (sk->sk_type == SOCK_STREAM)
goto new_alloc;
return NULL;
}
next = (u32)atomic_read(&sk->sk_zckey);
if ((u32)(uarg->id + uarg->len) == next) {
if (mm_account_pinned_pages(&uarg->mmp, size))
return NULL;
uarg->len++;
uarg->bytelen = bytelen;
atomic_set(&sk->sk_zckey, ++next);
sock_zerocopy_get(uarg);
return uarg;
}
}
new_alloc:
return sock_zerocopy_alloc(sk, size);
}
EXPORT_SYMBOL_GPL(sock_zerocopy_realloc);
static bool skb_zerocopy_notify_extend(struct sk_buff *skb, u32 lo, u16 len)
{
struct sock_exterr_skb *serr = SKB_EXT_ERR(skb);
u32 old_lo, old_hi;
u64 sum_len;
old_lo = serr->ee.ee_info;
old_hi = serr->ee.ee_data;
sum_len = old_hi - old_lo + 1ULL + len;
if (sum_len >= (1ULL << 32))
return false;
if (lo != old_hi + 1)
return false;
serr->ee.ee_data += len;
return true;
}
void sock_zerocopy_callback(struct ubuf_info *uarg, bool success)
{
struct sk_buff *tail, *skb = skb_from_uarg(uarg);
struct sock_exterr_skb *serr;
struct sock *sk = skb->sk;
struct sk_buff_head *q;
unsigned long flags;
u32 lo, hi;
u16 len;
mm_unaccount_pinned_pages(&uarg->mmp);
/* if !len, there was only 1 call, and it was aborted
* so do not queue a completion notification
*/
if (!uarg->len || sock_flag(sk, SOCK_DEAD))
goto release;
len = uarg->len;
lo = uarg->id;
hi = uarg->id + len - 1;
serr = SKB_EXT_ERR(skb);
memset(serr, 0, sizeof(*serr));
serr->ee.ee_errno = 0;
serr->ee.ee_origin = SO_EE_ORIGIN_ZEROCOPY;
serr->ee.ee_data = hi;
serr->ee.ee_info = lo;
if (!success)
serr->ee.ee_code |= SO_EE_CODE_ZEROCOPY_COPIED;
q = &sk->sk_error_queue;
spin_lock_irqsave(&q->lock, flags);
tail = skb_peek_tail(q);
if (!tail || SKB_EXT_ERR(tail)->ee.ee_origin != SO_EE_ORIGIN_ZEROCOPY ||
!skb_zerocopy_notify_extend(tail, lo, len)) {
__skb_queue_tail(q, skb);
skb = NULL;
}
spin_unlock_irqrestore(&q->lock, flags);
sk->sk_error_report(sk);
release:
consume_skb(skb);
sock_put(sk);
}
EXPORT_SYMBOL_GPL(sock_zerocopy_callback);
void sock_zerocopy_put(struct ubuf_info *uarg)
{
if (uarg && refcount_dec_and_test(&uarg->refcnt)) {
if (uarg->callback)
uarg->callback(uarg, uarg->zerocopy);
else
consume_skb(skb_from_uarg(uarg));
}
}
EXPORT_SYMBOL_GPL(sock_zerocopy_put);
void sock_zerocopy_put_abort(struct ubuf_info *uarg)
{
if (uarg) {
struct sock *sk = skb_from_uarg(uarg)->sk;
atomic_dec(&sk->sk_zckey);
uarg->len--;
sock_zerocopy_put(uarg);
}
}
EXPORT_SYMBOL_GPL(sock_zerocopy_put_abort);
extern int __zerocopy_sg_from_iter(struct sock *sk, struct sk_buff *skb,
struct iov_iter *from, size_t length);
int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
struct msghdr *msg, int len,
struct ubuf_info *uarg)
{
struct ubuf_info *orig_uarg = skb_zcopy(skb);
struct iov_iter orig_iter = msg->msg_iter;
int err, orig_len = skb->len;
/* An skb can only point to one uarg. This edge case happens when
* TCP appends to an skb, but zerocopy_realloc triggered a new alloc.
*/
if (orig_uarg && uarg != orig_uarg)
return -EEXIST;
err = __zerocopy_sg_from_iter(sk, skb, &msg->msg_iter, len);
if (err == -EFAULT || (err == -EMSGSIZE && skb->len == orig_len)) {
struct sock *save_sk = skb->sk;
/* Streams do not free skb on error. Reset to prev state. */
msg->msg_iter = orig_iter;
skb->sk = sk;
___pskb_trim(skb, orig_len);
skb->sk = save_sk;
return err;
}
skb_zcopy_set(skb, uarg);
return skb->len - orig_len;
}
EXPORT_SYMBOL_GPL(skb_zerocopy_iter_stream);
static int skb_zerocopy_clone(struct sk_buff *nskb, struct sk_buff *orig,
gfp_t gfp_mask)
{
if (skb_zcopy(orig)) {
if (skb_zcopy(nskb)) {
/* !gfp_mask callers are verified to !skb_zcopy(nskb) */
if (!gfp_mask) {
WARN_ON_ONCE(1);
return -ENOMEM;
}
if (skb_uarg(nskb) == skb_uarg(orig))
return 0;
if (skb_copy_ubufs(nskb, GFP_ATOMIC))
return -EIO;
}
skb_zcopy_set(nskb, skb_uarg(orig));
}
return 0;
}
/**
* skb_copy_ubufs - copy userspace skb frags buffers to kernel
* @skb: the skb to modify
* @gfp_mask: allocation priority
*
* This must be called on SKBTX_DEV_ZEROCOPY skb.
* It will copy all frags into kernel and drop the reference
* to userspace pages.
*
* If this function is called from an interrupt gfp_mask() must be
* %GFP_ATOMIC.
*
* Returns 0 on success or a negative error code on failure
* to allocate kernel memory to copy to.
*/
int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
{
int num_frags = skb_shinfo(skb)->nr_frags;
struct page *page, *head = NULL;
int i, new_frags;
u32 d_off;
if (skb_shared(skb) || skb_unclone(skb, gfp_mask))
return -EINVAL;
if (!num_frags)
goto release;
new_frags = (__skb_pagelen(skb) + PAGE_SIZE - 1) >> PAGE_SHIFT;
for (i = 0; i < new_frags; i++) {
page = alloc_page(gfp_mask);
if (!page) {
while (head) {
struct page *next = (struct page *)page_private(head);
put_page(head);
head = next;
}
return -ENOMEM;
}
set_page_private(page, (unsigned long)head);
head = page;
}
page = head;
d_off = 0;
for (i = 0; i < num_frags; i++) {
skb_frag_t *f = &skb_shinfo(skb)->frags[i];
u32 p_off, p_len, copied;
struct page *p;
u8 *vaddr;
skb_frag_foreach_page(f, f->page_offset, skb_frag_size(f),
p, p_off, p_len, copied) {
u32 copy, done = 0;
vaddr = kmap_atomic(p);
while (done < p_len) {
if (d_off == PAGE_SIZE) {
d_off = 0;
page = (struct page *)page_private(page);
}
copy = min_t(u32, PAGE_SIZE - d_off, p_len - done);
memcpy(page_address(page) + d_off,
vaddr + p_off + done, copy);
done += copy;
d_off += copy;
}
kunmap_atomic(vaddr);
}
}
/* skb frags release userspace buffers */
for (i = 0; i < num_frags; i++)
skb_frag_unref(skb, i);
/* skb frags point to kernel buffers */
for (i = 0; i < new_frags - 1; i++) {
__skb_fill_page_desc(skb, i, head, 0, PAGE_SIZE);
head = (struct page *)page_private(head);
}
__skb_fill_page_desc(skb, new_frags - 1, head, 0, d_off);
skb_shinfo(skb)->nr_frags = new_frags;
release:
skb_zcopy_clear(skb, false);
return 0;
}
EXPORT_SYMBOL_GPL(skb_copy_ubufs);
/**
* 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_fclones *fclones = container_of(skb,
struct sk_buff_fclones,
skb1);
struct sk_buff *n;
if (skb_orphan_frags(skb, gfp_mask))
return NULL;
if (skb->fclone == SKB_FCLONE_ORIG &&
refcount_read(&fclones->fclone_ref) == 1) {
n = &fclones->skb2;
refcount_set(&fclones->fclone_ref, 2);
} else {
if (skb_pfmemalloc(skb))
gfp_mask |= __GFP_MEMALLOC;
n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
if (!n)
return NULL;
n->fclone = SKB_FCLONE_UNAVAILABLE;
}
return __skb_clone(n, skb);
}
EXPORT_SYMBOL(skb_clone);
void skb_headers_offset_update(struct sk_buff *skb, int off)
{
/* Only adjust this if it actually is csum_start rather than csum */
if (skb->ip_summed == CHECKSUM_PARTIAL)
skb->csum_start += off;
/* {transport,network,mac}_header and tail are relative to skb->head */
skb->transport_header += off;
skb->network_header += off;
if (skb_mac_header_was_set(skb))
skb->mac_header += off;
skb->inner_transport_header += off;
skb->inner_network_header += off;
skb->inner_mac_header += off;
}
EXPORT_SYMBOL(skb_headers_offset_update);
void skb_copy_header(struct sk_buff *new, const struct sk_buff *old)
{
__copy_skb_header(new, old);
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;
}
EXPORT_SYMBOL(skb_copy_header);
static inline int skb_alloc_rx_flag(const struct sk_buff *skb)
{
if (skb_pfmemalloc(skb))
return SKB_ALLOC_RX;
return 0;
}
/**
* 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, gfp_t gfp_mask)
{
int headerlen = skb_headroom(skb);
unsigned int size = skb_end_offset(skb) + skb->data_len;
struct sk_buff *n = __alloc_skb(size, gfp_mask,
skb_alloc_rx_flag(skb), NUMA_NO_NODE);
if (!n)
return NULL;
/* Set the data pointer */
skb_reserve(n, headerlen);
/* Set the tail pointer and length */
skb_put(n, skb->len);
BUG_ON(skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len));
skb_copy_header(n, skb);
return n;
}
EXPORT_SYMBOL(skb_copy);
/**
* __pskb_copy_fclone - create copy of an sk_buff with private head.
* @skb: buffer to copy
* @headroom: headroom of new skb
* @gfp_mask: allocation priority
* @fclone: if true allocate the copy of the skb from the fclone
* cache instead of the head cache; it is recommended to set this
* to true for the cases where the copy will likely be cloned
*
* 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_fclone(struct sk_buff *skb, int headroom,
gfp_t gfp_mask, bool fclone)
{
unsigned int size = skb_headlen(skb) + headroom;
int flags = skb_alloc_rx_flag(skb) | (fclone ? SKB_ALLOC_FCLONE : 0);
struct sk_buff *n = __alloc_skb(size, gfp_mask, flags, NUMA_NO_NODE);
if (!n)
goto out;
/* Set the data pointer */
skb_reserve(n, headroom);
/* Set the tail pointer and length */
skb_put(n, skb_headlen(skb));
/* Copy the bytes */
skb_copy_from_linear_data(skb, n->data, n->len);
n->truesize += skb->data_len;
n->data_len = skb->data_len;
n->len = skb->len;
if (skb_shinfo(skb)->nr_frags) {
int i;
if (skb_orphan_frags(skb, gfp_mask) ||
skb_zerocopy_clone(n, skb, gfp_mask)) {
kfree_skb(n);
n = NULL;
goto out;
}
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
skb_frag_ref(skb, i);
}
skb_shinfo(n)->nr_frags = i;
}
if (skb_has_frag_list(skb)) {
skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
skb_clone_fraglist(n);
}
skb_copy_header(n, skb);
out:
return n;
}
EXPORT_SYMBOL(__pskb_copy_fclone);
/**
* 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,
gfp_t gfp_mask)
{
int i, osize = skb_end_offset(skb);
int size = osize + nhead + ntail;
long off;
u8 *data;
BUG_ON(nhead < 0);
BUG_ON(skb_shared(skb));
size = SKB_DATA_ALIGN(size);
if (skb_pfmemalloc(skb))
gfp_mask |= __GFP_MEMALLOC;
data = kmalloc_reserve(size + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
gfp_mask, NUMA_NO_NODE, NULL);
if (!data)
goto nodata;
size = SKB_WITH_OVERHEAD(ksize(data));
/* 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_pointer(skb) - skb->head);
memcpy((struct skb_shared_info *)(data + size),
skb_shinfo(skb),
offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
/*
* if shinfo is shared we must drop the old head gracefully, but if it
* is not we can just drop the old head and let the existing refcount
* be since all we did is relocate the values
*/
if (skb_cloned(skb)) {
if (skb_orphan_frags(skb, gfp_mask))
goto nofrags;
if (skb_zcopy(skb))
refcount_inc(&skb_uarg(skb)->refcnt);
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
skb_frag_ref(skb, i);
if (skb_has_frag_list(skb))
skb_clone_fraglist(skb);
skb_release_data(skb);
} else {
skb_free_head(skb);
}
off = (data + nhead) - skb->head;
skb->head = data;
skb->head_frag = 0;
skb->data += off;
#ifdef NET_SKBUFF_DATA_USES_OFFSET
skb->end = size;
off = nhead;
#else
skb->end = skb->head + size;
#endif
skb->tail += off;
skb_headers_offset_update(skb, nhead);
skb->cloned = 0;
skb->hdr_len = 0;
skb->nohdr = 0;
atomic_set(&skb_shinfo(skb)->dataref, 1);
skb_metadata_clear(skb);
/* It is not generally safe to change skb->truesize.
* For the moment, we really care of rx path, or
* when skb is orphaned (not attached to a socket).
*/
if (!skb->sk || skb->destructor == sock_edemux)
skb->truesize += size - osize;
return 0;
nofrags:
kfree(data);
nodata:
return -ENOMEM;
}
EXPORT_SYMBOL(pskb_expand_head);
/* 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;
}
EXPORT_SYMBOL(skb_realloc_headroom);
/**
* 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,
int newheadroom, int newtailroom,
gfp_t gfp_mask)
{
/*
* Allocate the copy buffer
*/
struct sk_buff *n = __alloc_skb(newheadroom + skb->len + newtailroom,
gfp_mask, skb_alloc_rx_flag(skb),
NUMA_NO_NODE);
int oldheadroom = skb_headroom(skb);
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 = oldheadroom;
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. */
BUG_ON(skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
skb->len + head_copy_len));
skb_copy_header(n, skb);
skb_headers_offset_update(n, newheadroom - oldheadroom);
return n;
}
EXPORT_SYMBOL(skb_copy_expand);
/**
* __skb_pad - zero pad the tail of an skb
* @skb: buffer to pad
* @pad: space to pad
* @free_on_error: free buffer on error
*
* 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 error in out of memory cases. The skb is freed on error
* if @free_on_error is true.
*/
int __skb_pad(struct sk_buff *skb, int pad, bool free_on_error)
{
int err;
int ntail;
/* If the skbuff is non linear tailroom is always zero.. */
if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
memset(skb->data+skb->len, 0, pad);
return 0;
}
ntail = skb->data_len + pad - (skb->end - skb->tail);
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:
if (free_on_error)
kfree_skb(skb);
return err;
}
EXPORT_SYMBOL(__skb_pad);
/**
* pskb_put - add data to the tail of a potentially fragmented buffer
* @skb: start of the buffer to use
* @tail: tail fragment of the buffer to use
* @len: amount of data to add
*
* This function extends the used data area of the potentially
* fragmented buffer. @tail must be the last fragment of @skb -- or
* @skb itself. If this would exceed the total buffer size the kernel
* will panic. A pointer to the first byte of the extra data is
* returned.
*/
void *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len)
{
if (tail != skb) {
skb->data_len += len;
skb->len += len;
}
return skb_put(tail, len);
}
EXPORT_SYMBOL_GPL(pskb_put);
/**
* 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.
*/
void *skb_put(struct sk_buff *skb, unsigned int len)
{
void *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);
/**
* 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.
*/
void *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);
/**
* 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.
*/
void *skb_pull(struct sk_buff *skb, unsigned int len)
{
return skb_pull_inline(skb, len);
}
EXPORT_SYMBOL(skb_pull);
/**
* 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);
/* Trims skb to length len. It can change skb pointers.
*/
int ___pskb_trim(struct sk_buff *skb, unsigned int len)
{
struct sk_buff **fragp;
struct sk_buff *frag;
int offset = skb_headlen(skb);
int nfrags = skb_shinfo(skb)->nr_frags;
int i;
int err;
if (skb_cloned(skb) &&
unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
return err;
i = 0;
if (offset >= len)
goto drop_pages;
for (; i < nfrags; i++) {
int end = offset + skb_frag_size(&skb_shinfo(skb)->frags[i]);
if (end < len) {
offset = end;
continue;
}
skb_frag_size_set(&skb_shinfo(skb)->frags[i++], len - offset);
drop_pages:
skb_shinfo(skb)->nr_frags = i;
for (; i < nfrags; i++)
skb_frag_unref(skb, i);
if (skb_has_frag_list(skb))
skb_drop_fraglist(skb);
goto done;
}
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;
consume_skb(frag);
frag = nfrag;
*fragp = frag;
}
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;
}
done:
if (len > skb_headlen(skb)) {
skb->data_len -= skb->len - len;
skb->len = len;
} else {
skb->len = len;
skb->data_len = 0;
skb_set_tail_pointer(skb, len);
}
if (!skb->sk || skb->destructor == sock_edemux)
skb_condense(skb);
return 0;
}
EXPORT_SYMBOL(___pskb_trim);
/* Note : use pskb_trim_rcsum() instead of calling this directly
*/
int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len)
{
if (skb->ip_summed == CHECKSUM_COMPLETE) {
int delta = skb->len - len;
skb->csum = csum_block_sub(skb->csum,
skb_checksum(skb, len, delta, 0),
len);
}
return __pskb_trim(skb, len);
}
EXPORT_SYMBOL(pskb_trim_rcsum_slow);
/**
* __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.
*/
void *__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;
}
BUG_ON(skb_copy_bits(skb, skb_headlen(skb),
skb_tail_pointer(skb), delta));
/* Optimization: no fragments, no reasons to preestimate
* size of pulled pages. Superb.
*/
if (!skb_has_frag_list(skb))
goto pull_pages;
/* Estimate size of pulled pages. */
eat = delta;
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
if (size >= eat)
goto pull_pages;
eat -= size;
}
/* If we need update frag list, we are in troubles.
* Certainly, it is 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 {
BUG_ON(!list);
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)) {
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++) {
int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
if (size <= eat) {
skb_frag_unref(skb, i);
eat -= size;
} else {
skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
if (eat) {
skb_shinfo(skb)->frags[k].page_offset += eat;
skb_frag_size_sub(&skb_shinfo(skb)->frags[k], eat);
if (!i)
goto end;
eat = 0;
}
k++;
}
}
skb_shinfo(skb)->nr_frags = k;
end:
skb->tail += delta;
skb->data_len -= delta;
if (!skb->data_len)
skb_zcopy_clear(skb, false);
return skb_tail_pointer(skb);
}
EXPORT_SYMBOL(__pskb_pull_tail);
/**
* skb_copy_bits - copy bits from skb to kernel buffer
* @skb: source skb
* @offset: offset in source
* @to: destination buffer
* @len: number of bytes to copy
*
* Copy the specified number of bytes from the source skb to the
* destination buffer.
*
* CAUTION ! :
* If its prototype is ever changed,
* check arch/{*}/net/{*}.S files,
* since it is called from BPF assembly code.
*/
int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
{
int start = skb_headlen(skb);
struct sk_buff *frag_iter;
int i, copy;
if (offset > (int)skb->len - len)
goto fault;
/* Copy header. */
if ((copy = start - offset) > 0) {
if (copy > len)
copy = len;
skb_copy_from_linear_data_offset(skb, offset, to, copy);
if ((len -= copy) == 0)
return 0;
offset += copy;
to += copy;
}
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
int end;
skb_frag_t *f = &skb_shinfo(skb)->frags[i];
WARN_ON(start > offset + len);
end = start + skb_frag_size(f);
if ((copy = end - offset) > 0) {
u32 p_off, p_len, copied;
struct page *p;
u8 *vaddr;
if (copy > len)
copy = len;
skb_frag_foreach_page(f,
f->page_offset + offset - start,
copy, p, p_off, p_len, copied) {
vaddr = kmap_atomic(p);
memcpy(to + copied, vaddr + p_off, p_len);
kunmap_atomic(vaddr);
}
if ((len -= copy) == 0)
return 0;
offset += copy;
to += copy;
}
start = end;
}
skb_walk_frags(skb, frag_iter) {
int end;
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;
}
start = end;
}
if (!len)
return 0;
fault:
return -EFAULT;
}
EXPORT_SYMBOL(skb_copy_bits);
/*
* 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)
{
put_page(spd->pages[i]);
}
static struct page *linear_to_page(struct page *page, unsigned int *len,
unsigned int *offset,
struct sock *sk)
{
struct page_frag *pfrag = sk_page_frag(sk);
if (!sk_page_frag_refill(sk, pfrag))
return NULL;
*len = min_t(unsigned int, *len, pfrag->size - pfrag->offset);
memcpy(page_address(pfrag->page) + pfrag->offset,
page_address(page) + *offset, *len);
*offset = pfrag->offset;
pfrag->offset += *len;
return pfrag->page;
}
static bool spd_can_coalesce(const struct splice_pipe_desc *spd,
struct page *page,
unsigned int offset)
{
return spd->nr_pages &&
spd->pages[spd->nr_pages - 1] == page &&
(spd->partial[spd->nr_pages - 1].offset +
spd->partial[spd->nr_pages - 1].len == offset);
}
/*
* Fill page/offset/length into spd, if it can hold more pages.
*/
static bool spd_fill_page(struct splice_pipe_desc *spd,
struct pipe_inode_info *pipe, struct page *page,
unsigned int *len, unsigned int offset,
bool linear,
struct sock *sk)
{
if (unlikely(spd->nr_pages == MAX_SKB_FRAGS))
return true;
if (linear) {
page = linear_to_page(page, len, &offset, sk);
if (!page)
return true;
}
if (spd_can_coalesce(spd, page, offset)) {
spd->partial[spd->nr_pages - 1].len += *len;
return false;
}
get_page(page);
spd->pages[spd->nr_pages] = page;
spd->partial[spd->nr_pages].len = *len;
spd->partial[spd->nr_pages].offset = offset;
spd->nr_pages++;
return false;
}
static bool __splice_segment(struct page *page, unsigned int poff,
unsigned int plen, unsigned int *off,
unsigned int *len,
struct splice_pipe_desc *spd, bool linear,
struct sock *sk,
struct pipe_inode_info *pipe)
{
if (!*len)
return true;
/* skip this segment if already processed */
if (*off >= plen) {
*off -= plen;
return false;
}
/* ignore any bits we already processed */
poff += *off;
plen -= *off;
*off = 0;
do {
unsigned int flen = min(*len, plen);
if (spd_fill_page(spd, pipe, page, &flen, poff,
linear, sk))
return true;
poff += flen;
plen -= flen;
*len -= flen;
} while (*len && plen);
return false;
}
/*
* Map linear and fragment data from the skb to spd. It reports true if the
* pipe is full or if we already spliced the requested length.
*/
static bool __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)
{
int seg;
struct sk_buff *iter;
/* map the linear part :
* If skb->head_frag is set, this 'linear' part is backed by a
* fragment, and if the head is not shared with any clones then
* we can avoid a copy since we own the head portion of this page.
*/
if (__splice_segment(virt_to_page(skb->data),
(unsigned long) skb->data & (PAGE_SIZE - 1),
skb_headlen(skb),
offset, len, spd,
skb_head_is_locked(skb),
sk, pipe))
return true;
/*
* then map the fragments
*/
for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
if (__splice_segment(skb_frag_page(f),
f->page_offset, skb_frag_size(f),
offset, len, spd, false, sk, pipe))
return true;
}
skb_walk_frags(skb, iter) {
if (*offset >= iter->len) {
*offset -= iter->len;
continue;
}
/* __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.
*/
if (__skb_splice_bits(iter, pipe, offset, len, spd, sk))
return true;
}
return false;
}
/*
* Map data from the skb to a pipe. Should handle both the linear part,
* the fragments, and the frag list.
*/
int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
struct pipe_inode_info *pipe, unsigned int tlen,
unsigned int flags)
{
struct partial_page partial[MAX_SKB_FRAGS];
struct page *pages[MAX_SKB_FRAGS];
struct splice_pipe_desc spd = {
.pages = pages,
.partial = partial,
.nr_pages_max = MAX_SKB_FRAGS,
.ops = &nosteal_pipe_buf_ops,
.spd_release = sock_spd_release,
};
int ret = 0;
__skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk);
if (spd.nr_pages)
ret = splice_to_pipe(pipe, &spd);
return ret;
}
EXPORT_SYMBOL_GPL(skb_splice_bits);
/* Send skb data on a socket. Socket must be locked. */
int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
int len)
{
unsigned int orig_len = len;
struct sk_buff *head = skb;
unsigned short fragidx;
int slen, ret;
do_frag_list:
/* Deal with head data */
while (offset < skb_headlen(skb) && len) {
struct kvec kv;
struct msghdr msg;
slen = min_t(int, len, skb_headlen(skb) - offset);
kv.iov_base = skb->data + offset;
kv.iov_len = slen;
memset(&msg, 0, sizeof(msg));
ret = kernel_sendmsg_locked(sk, &msg, &kv, 1, slen);
if (ret <= 0)
goto error;
offset += ret;
len -= ret;
}
/* All the data was skb head? */
if (!len)
goto out;
/* Make offset relative to start of frags */
offset -= skb_headlen(skb);
/* Find where we are in frag list */
for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
skb_frag_t *frag = &skb_shinfo(skb)->frags[fragidx];
if (offset < frag->size)
break;
offset -= frag->size;
}
for (; len && fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
skb_frag_t *frag = &skb_shinfo(skb)->frags[fragidx];
slen = min_t(size_t, len, frag->size - offset);
while (slen) {
ret = kernel_sendpage_locked(sk, frag->page.p,
frag->page_offset + offset,
slen, MSG_DONTWAIT);
if (ret <= 0)
goto error;
len -= ret;
offset += ret;
slen -= ret;
}
offset = 0;
}
if (len) {
/* Process any frag lists */
if (skb == head) {
if (skb_has_frag_list(skb)) {
skb = skb_shinfo(skb)->frag_list;
goto do_frag_list;
}
} else if (skb->next) {
skb = skb->next;
goto do_frag_list;
}
}
out:
return orig_len - len;
error:
return orig_len == len ? ret : orig_len - len;
}
EXPORT_SYMBOL_GPL(skb_send_sock_locked);
/* Send skb data on a socket. */
int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len)
{
int ret = 0;
lock_sock(sk);
ret = skb_send_sock_locked(sk, skb, offset, len);
release_sock(sk);
return ret;
}
EXPORT_SYMBOL_GPL(skb_send_sock);
/**
* 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.
*/
int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
{
int start = skb_headlen(skb);
struct sk_buff *frag_iter;
int i, copy;
if (offset > (int)skb->len - len)
goto fault;
if ((copy = start - offset) > 0) {
if (copy > len)
copy = len;
skb_copy_to_linear_data_offset(skb, offset, from, copy);
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];
int end;
WARN_ON(start > offset + len);
end = start + skb_frag_size(frag);
if ((copy = end - offset) > 0) {
u32 p_off, p_len, copied;
struct page *p;
u8 *vaddr;
if (copy > len)
copy = len;
skb_frag_foreach_page(frag,
frag->page_offset + offset - start,
copy, p, p_off, p_len, copied) {
vaddr = kmap_atomic(p);
memcpy(vaddr + p_off, from + copied, p_len);
kunmap_atomic(vaddr);
}
if ((len -= copy) == 0)
return 0;
offset += copy;
from += copy;
}
start = end;
}
skb_walk_frags(skb, frag_iter) {
int end;
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;
}
start = end;
}
if (!len)
return 0;
fault:
return -EFAULT;
}
EXPORT_SYMBOL(skb_store_bits);
/* Checksum skb data. */
__wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
__wsum csum, const struct skb_checksum_ops *ops)
{
int start = skb_headlen(skb);
int i, copy = start - offset;
struct sk_buff *frag_iter;
int pos = 0;
/* Checksum header. */
if (copy > 0) {
if (copy > len)
copy = len;
csum = ops->update(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;
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
WARN_ON(start > offset + len);
end = start + skb_frag_size(frag);
if ((copy = end - offset) > 0) {
u32 p_off, p_len, copied;
struct page *p;
__wsum csum2;
u8 *vaddr;
if (copy > len)
copy = len;
skb_frag_foreach_page(frag,
frag->page_offset + offset - start,
copy, p, p_off, p_len, copied) {
vaddr = kmap_atomic(p);
csum2 = ops->update(vaddr + p_off, p_len, 0);
kunmap_atomic(vaddr);
csum = ops->combine(csum, csum2, pos, p_len);
pos += p_len;
}
if (!(len -= copy))
return csum;
offset += copy;
}
start = end;
}
skb_walk_frags(skb, frag_iter) {
int end;
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, ops);
csum = ops->combine(csum, csum2, pos, copy);
if ((len -= copy) == 0)
return csum;
offset += copy;
pos += copy;
}
start = end;
}
BUG_ON(len);
return csum;
}
EXPORT_SYMBOL(__skb_checksum);
__wsum skb_checksum(const struct sk_buff *skb, int offset,
int len, __wsum csum)
{
const struct skb_checksum_ops ops = {
.update = csum_partial_ext,
.combine = csum_block_add_ext,
};
return __skb_checksum(skb, offset, len, csum, &ops);
}
EXPORT_SYMBOL(skb_checksum);
/* Both of above in one bottle. */
__wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
u8 *to, int len, __wsum csum)
{
int start = skb_headlen(skb);
int i, copy = start - offset;
struct sk_buff *frag_iter;
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;
WARN_ON(start > offset + len);
end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
if ((copy = end - offset) > 0) {
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
u32 p_off, p_len, copied;
struct page *p;
__wsum csum2;
u8 *vaddr;
if (copy > len)
copy = len;
skb_frag_foreach_page(frag,
frag->page_offset + offset - start,
copy, p, p_off, p_len, copied) {
vaddr = kmap_atomic(p);
csum2 = csum_partial_copy_nocheck(vaddr + p_off,
to + copied,
p_len, 0);
kunmap_atomic(vaddr);
csum = csum_block_add(csum, csum2, pos);
pos += p_len;
}
if (!(len -= copy))
return csum;
offset += copy;
to += copy;
}
start = end;
}
skb_walk_frags(skb, frag_iter) {
__wsum csum2;
int end;
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;
}
start = end;
}
BUG_ON(len);
return csum;
}
EXPORT_SYMBOL(skb_copy_and_csum_bits);
static __wsum warn_crc32c_csum_update(const void *buff, int len, __wsum sum)
{
net_warn_ratelimited(
"%s: attempt to compute crc32c without libcrc32c.ko\n",
__func__);
return 0;
}
static __wsum warn_crc32c_csum_combine(__wsum csum, __wsum csum2,
int offset, int len)
{
net_warn_ratelimited(
"%s: attempt to compute crc32c without libcrc32c.ko\n",
__func__);
return 0;
}
static const struct skb_checksum_ops default_crc32c_ops = {
.update = warn_crc32c_csum_update,
.combine = warn_crc32c_csum_combine,
};
const struct skb_checksum_ops *crc32c_csum_stub __read_mostly =
&default_crc32c_ops;
EXPORT_SYMBOL(crc32c_csum_stub);
/**
* skb_zerocopy_headlen - Calculate headroom needed for skb_zerocopy()
* @from: source buffer
*
* Calculates the amount of linear headroom needed in the 'to' skb passed
* into skb_zerocopy().
*/
unsigned int
skb_zerocopy_headlen(const struct sk_buff *from)
{
unsigned int hlen = 0;
if (!from->head_frag ||
skb_headlen(from) < L1_CACHE_BYTES ||
skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS)
hlen = skb_headlen(from);
if (skb_has_frag_list(from))
hlen = from->len;
return hlen;
}
EXPORT_SYMBOL_GPL(skb_zerocopy_headlen);
/**
* skb_zerocopy - Zero copy skb to skb
* @to: destination buffer
* @from: source buffer
* @len: number of bytes to copy from source buffer
* @hlen: size of linear headroom in destination buffer
*
* Copies up to `len` bytes from `from` to `to` by creating references
* to the frags in the source buffer.
*
* The `hlen` as calculated by skb_zerocopy_headlen() specifies the
* headroom in the `to` buffer.
*
* Return value:
* 0: everything is OK
* -ENOMEM: couldn't orphan frags of @from due to lack of memory
* -EFAULT: skb_copy_bits() found some problem with skb geometry
*/
int
skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen)
{
int i, j = 0;
int plen = 0; /* length of skb->head fragment */
int ret;
struct page *page;
unsigned int offset;
BUG_ON(!from->head_frag && !hlen);
/* dont bother with small payloads */
if (len <= skb_tailroom(to))
return skb_copy_bits(from, 0, skb_put(to, len), len);
if (hlen) {
ret = skb_copy_bits(from, 0, skb_put(to, hlen), hlen);
if (unlikely(ret))
return ret;
len -= hlen;
} else {
plen = min_t(int, skb_headlen(from), len);
if (plen) {
page = virt_to_head_page(from->head);
offset = from->data - (unsigned char *)page_address(page);
__skb_fill_page_desc(to, 0, page, offset, plen);
get_page(page);
j = 1;
len -= plen;
}
}
to->truesize += len + plen;
to->len += len + plen;
to->data_len += len + plen;
if (unlikely(skb_orphan_frags(from, GFP_ATOMIC))) {
skb_tx_error(from);
return -ENOMEM;
}
skb_zerocopy_clone(to, from, GFP_ATOMIC);
for (i = 0; i < skb_shinfo(from)->nr_frags; i++) {
if (!len)
break;
skb_shinfo(to)->frags[j] = skb_shinfo(from)->frags[i];
skb_shinfo(to)->frags[j].size = min_t(int, skb_shinfo(to)->frags[j].size, len);
len -= skb_shinfo(to)->frags[j].size;
skb_frag_ref(to, j);
j++;
}
skb_shinfo(to)->nr_frags = j;
return 0;
}
EXPORT_SYMBOL_GPL(skb_zerocopy);
void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
{
__wsum csum;
long csstart;
if (skb->ip_summed == CHECKSUM_PARTIAL)
csstart = skb_checksum_start_offset(skb);
else
csstart = skb_headlen(skb);
BUG_ON(csstart > skb_headlen(skb));
skb_copy_from_linear_data(skb, to, 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_PARTIAL) {
long csstuff = csstart + skb->csum_offset;
*((__sum16 *)(to + csstuff)) = csum_fold(csum);
}
}
EXPORT_SYMBOL(skb_copy_and_csum_dev);
/**
* 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;
}
EXPORT_SYMBOL(skb_dequeue);
/**
* 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;
}
EXPORT_SYMBOL(skb_dequeue_tail);
/**
* 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);
}
EXPORT_SYMBOL(skb_queue_purge);
/**
* skb_rbtree_purge - empty a skb rbtree
* @root: root of the rbtree to empty
* Return value: the sum of truesizes of all purged skbs.
*
* Delete all buffers on an &sk_buff rbtree. Each buffer is removed from
* the list and one reference dropped. This function does not take
* any lock. Synchronization should be handled by the caller (e.g., TCP
* out-of-order queue is protected by the socket lock).
*/
unsi