diff options
Diffstat (limited to 'net/core/skbuff.c')
| -rw-r--r-- | net/core/skbuff.c | 1460 |
1 files changed, 1460 insertions, 0 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c new file mode 100644 index 000000000000..bf02ca9f80ac --- /dev/null +++ b/net/core/skbuff.c @@ -0,0 +1,1460 @@ +/* + * 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); |