/* * 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/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/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 <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> #include "kmap_skb.h" static struct kmem_cache *skbuff_head_cache __read_mostly; static struct kmem_cache *skbuff_fclone_cache __read_mostly; static void sock_pipe_buf_release(struct pipe_inode_info *pipe, struct pipe_buffer *buf) { struct sk_buff *skb = (struct sk_buff *) buf->private; kfree_skb(skb); } static void sock_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf) { struct sk_buff *skb = (struct sk_buff *) buf->private; skb_get(skb); } static int sock_pipe_buf_steal(struct pipe_inode_info *pipe, struct pipe_buffer *buf) { return 1; } /* Pipe buffer operations for a socket. */ static struct pipe_buf_operations sock_pipe_buf_ops = { .can_merge = 0, .map = generic_pipe_buf_map, .unmap = generic_pipe_buf_unmap, .confirm = generic_pipe_buf_confirm, .release = sock_pipe_buf_release, .steal = sock_pipe_buf_steal, .get = sock_pipe_buf_get, }; /* * 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_EMERG "skb_over_panic: text:%p len:%d put:%d head:%p " "data:%p tail:%#lx end:%#lx dev:%s\n", here, skb->len, sz, skb->head, skb->data, (unsigned long)skb->tail, (unsigned long)skb->end, 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_EMERG "skb_under_panic: text:%p len:%d put:%d head:%p " "data:%p tail:%#lx end:%#lx dev:%s\n", here, skb->len, sz, skb->head, skb->data, (unsigned long)skb->tail, (unsigned long)skb->end, skb->dev ? skb->dev->name : "<NULL>"); BUG(); } void skb_truesize_bug(struct sk_buff *skb) { printk(KERN_ERR "SKB BUG: Invalid truesize (%u) " "len=%u, sizeof(sk_buff)=%Zd\n", skb->truesize, skb->len, sizeof(struct sk_buff)); } EXPORT_SYMBOL(skb_truesize_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 * @fclone: allocate from fclone cache instead of head cache * and allocate a cloned (child) skb * @node: numa node to allocate memory on * * 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, gfp_t gfp_mask, int fclone, int node) { struct kmem_cache *cache; struct skb_shared_info *shinfo; struct sk_buff *skb; u8 *data; cache = fclone ? skbuff_fclone_cache : skbuff_head_cache; /* Get the HEAD */ skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node); if (!skb) goto out; size = SKB_DATA_ALIGN(size); data = kmalloc_node_track_caller(size + sizeof(struct skb_shared_info), gfp_mask, node); if (!data) goto nodata; /* * See comment in sk_buff definition, just before the 'tail' member */ memset(skb, 0, offsetof(struct sk_buff, tail)); skb->truesize = size + sizeof(struct sk_buff); atomic_set(&skb->users, 1); skb->head = data; skb->data = data; skb_reset_tail_pointer(skb); skb->end = skb->tail + size; /* make sure we initialize shinfo sequentially */ shinfo = skb_shinfo(skb); atomic_set(&shinfo->dataref, 1); shinfo->nr_frags = 0; shinfo->gso_size = 0; shinfo->gso_segs = 0; shinfo->gso_type = 0; shinfo->ip6_frag_id = 0; shinfo->frag_list = NULL; if (fclone) { struct sk_buff *child = skb + 1; atomic_t *fclone_ref = (atomic_t *) (child + 1); skb->fclone = SKB_FCLONE_ORIG; atomic_set(fclone_ref, 1); child->fclone = SKB_FCLONE_UNAVAILABLE; } out: return skb; nodata: kmem_cache_free(cache, skb); skb = NULL; goto out; } /** * __netdev_alloc_skb - allocate an skbuff for rx on a specific device * @dev: network device to receive on * @length: length to allocate * @gfp_mask: get_free_pages mask, passed to alloc_skb * * Allocate a new &sk_buff and assign it a usage count of one. The * buffer has unspecified headroom built in. Users should allocate * the headroom they think they need without accounting for the * built in space. The built in space is used for optimisations. * * %NULL is returned if there is no free memory. */ struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int length, gfp_t gfp_mask) { int node = dev->dev.parent ? dev_to_node(dev->dev.parent) : -1; struct sk_buff *skb; skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, node); if (likely(skb)) { skb_reserve(skb, NET_SKB_PAD); skb->dev = dev; } return skb; } /** * dev_alloc_skb - allocate an skbuff for receiving * @length: length to allocate * * Allocate a new &sk_buff and assign it a usage count of one. The * buffer has unspecified headroom built in. Users should allocate * the headroom they think they need without accounting for the * built in space. The built in space is used for optimisations. * * %NULL is returned if there is no free memory. Although this function * allocates memory it can be called from an interrupt. */ struct sk_buff *dev_alloc_skb(unsigned int length) { /* * There is more code here than it seems: * __dev_alloc_skb is an inline */ return __dev_alloc_skb(length, GFP_ATOMIC); } EXPORT_SYMBOL(dev_alloc_skb); static void skb_drop_list(struct sk_buff **listp) { struct sk_buff *list = *listp; *listp = NULL; do { struct sk_buff *this = list; list = list->next; kfree_skb(this); } while (list); } 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; for (list = skb_shinfo(skb)->frag_list; list; list = list->next) skb_get(list); } static 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. */ static void kfree_skbmem(struct sk_buff *skb) { struct sk_buff *other; atomic_t *fclone_ref; switch (skb->fclone) { case SKB_FCLONE_UNAVAILABLE: kmem_cache_free(skbuff_head_cache, skb); break; case SKB_FCLONE_ORIG: fclone_ref = (atomic_t *) (skb + 2); if (atomic_dec_and_test(fclone_ref)) kmem_cache_free(skbuff_fclone_cache, skb); break; case SKB_FCLONE_CLONE: fclone_ref = (atomic_t *) (skb + 1); other = skb - 1; /* The clone portion is available for * fast-cloning again. */ skb->fclone = SKB_FCLONE_UNAVAILABLE; if (atomic_dec_and_test(fclone_ref)) kmem_cache_free(skbuff_fclone_cache, other); break; } } /* Free everything but the sk_buff shell. */ static void skb_release_all(struct sk_buff *skb) { dst_release(skb->dst); #ifdef CONFIG_XFRM secpath_put(skb->sp); #endif if (skb->destructor) { WARN_ON(in_irq()); skb->destructor(skb); } #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE) nf_conntrack_put(skb->nfct); nf_conntrack_put_reasm(skb->nfct_reasm); #endif #ifdef CONFIG_BRIDGE_NETFILTER nf_bridge_put(skb->nf_bridge); #endif /* XXX: IS this still necessary? - JHS */ #ifdef CONFIG_NET_SCHED skb->tc_index = 0; #ifdef CONFIG_NET_CLS_ACT skb->tc_verd = 0; #endif #endif 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); } /** * kfree_skb - free an sk_buff * @skb: buffer to free * * Drop a reference to the buffer and free it if the usage count has * hit zero. */ void kfree_skb(struct sk_buff *skb) { if (unlikely(!skb)) return; if (likely(atomic_read(&skb->users) == 1)) smp_rmb(); else if (likely(!atomic_dec_and_test(&skb->users))) return; __kfree_skb(skb); } static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old) { new->tstamp = old->tstamp; new->dev = old->dev; new->transport_header = old->transport_header; new->network_header = old->network_header; new->mac_header = old->mac_header; new->dst = dst_clone(old->dst); #ifdef CONFIG_INET new->sp = secpath_get(old->sp); #endif memcpy(new->cb, old->cb, sizeof(old->cb)); new->csum_start = old->csum_start; new->csum_offset = old->csum_offset; new->local_df = old->local_df; new->pkt_type = old->pkt_type; new->ip_summed = old->ip_summed; skb_copy_queue_mapping(new, old); new->priority = old->priority; #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) new->ipvs_property = old->ipvs_property; #endif new->protocol = old->protocol; new->mark = old->mark; __nf_copy(new, old); #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \ defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE) new->nf_trace = old->nf_trace; #endif #ifdef CONFIG_NET_SCHED new->tc_index = old->tc_index; #ifdef CONFIG_NET_CLS_ACT new->tc_verd = old->tc_verd; #endif #endif skb_copy_secmark(new, old); } 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->destructor = NULL; C(iif); C(tail); C(end); C(head); C(data); C(truesize); atomic_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); /** * skb_clone - duplicate an sk_buff * @skb: buffer to clone * @gfp_mask: allocation priority * * Duplicate an &sk_buff. The new one is not owned by a socket. Both * copies share the same packet data but not structure. The new * buffer has a reference count of 1. If the allocation fails the * function returns %NULL otherwise the new buffer is returned. * * If this function is called from an interrupt gfp_mask() must be * %GFP_ATOMIC. */ struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask) { struct sk_buff *n; n = skb + 1; if (skb->fclone == SKB_FCLONE_ORIG && n->fclone == SKB_FCLONE_UNAVAILABLE) { atomic_t *fclone_ref = (atomic_t *) (n + 1); n->fclone = SKB_FCLONE_CLONE; atomic_inc(fclone_ref); } else { n = kmem_cache_alloc(skbuff_head_cache, gfp_mask); if (!n) return NULL; n->fclone = SKB_FCLONE_UNAVAILABLE; } return __skb_clone(n, skb); } static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old) { #ifndef NET_SKBUFF_DATA_USES_OFFSET /* * Shift between the two data areas in bytes */ unsigned long offset = new->data - old->data; #endif __copy_skb_header(new, old); #ifndef NET_SKBUFF_DATA_USES_OFFSET /* {transport,network,mac}_header are relative to skb->head */ new->transport_header += offset; new->network_header += offset; new->mac_header += offset; #endif 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; } /** * 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->data - skb->head; /* * Allocate the copy buffer */ struct sk_buff *n; #ifdef NET_SKBUFF_DATA_USES_OFFSET n = alloc_skb(skb->end + skb->data_len, gfp_mask); #else n = alloc_skb(skb->end - skb->head + skb->data_len, gfp_mask); #endif if (!n) return NULL; /* Set the data pointer */ skb_reserve(n, headerlen); /* Set the tail pointer and length */ skb_put(n, skb->len); if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len)) BUG(); copy_skb_header(n, skb); return n; } /** * 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, gfp_t gfp_mask) { /* * Allocate the copy buffer */ struct sk_buff *n; #ifdef NET_SKBUFF_DATA_USES_OFFSET n = alloc_skb(skb->end, gfp_mask); #else n = alloc_skb(skb->end - skb->head, gfp_mask); #endif 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 */ 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; 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, gfp_t gfp_mask) { int i; u8 *data; #ifdef NET_SKBUFF_DATA_USES_OFFSET int size = nhead + skb->end + ntail; #else int size = nhead + (skb->end - skb->head) + ntail; #endif 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. */ #ifdef NET_SKBUFF_DATA_USES_OFFSET memcpy(data + nhead, skb->head, skb->tail); #else memcpy(data + nhead, skb->head, skb->tail - skb->head); #endif memcpy(data + size, skb_end_pointer(skb), 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->data += off; #ifdef NET_SKBUFF_DATA_USES_OFFSET skb->end = size; off = nhead; #else skb->end = skb->head + size; #endif /* {transport,network,mac}_header and tail are relative to skb->head */ skb->tail += off; skb->transport_header += off; skb->network_header += off; skb->mac_header += off; skb->csum_start += nhead; skb->cloned = 0; skb->hdr_len = 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. */ 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); int oldheadroom = skb_headroom(skb); int head_copy_len, head_copy_off; int 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. */ if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off, skb->len + head_copy_len)) BUG(); copy_skb_header(n, skb); off = newheadroom - oldheadroom; n->csum_start += off; #ifdef NET_SKBUFF_DATA_USES_OFFSET n->transport_header += off; n->network_header += off; n->mac_header += off; #endif 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 error in out of memory cases. The skb is freed on error. */ int skb_pad(struct sk_buff *skb, int pad) { 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: kfree_skb(skb); return err; } /** * skb_put - add data to a buffer * @skb: buffer to use * @len: amount of data to add * * This function extends the used data area of the buffer. If this would * exceed the total buffer size the kernel will panic. A pointer to the * first byte of the extra data is returned. */ unsigned char *skb_put(struct sk_buff *skb, unsigned int len) { unsigned char *tmp = skb_tail_pointer(skb); SKB_LINEAR_ASSERT(skb); skb->tail += len; skb->len += len; if (unlikely(skb->tail > skb->end)) skb_over_panic(skb, len, __builtin_return_address(0)); return tmp; } EXPORT_SYMBOL(skb_put); /** * skb_push - add data to the start of a buffer * @skb: buffer to use * @len: amount of data to add * * This function extends the used data area of the buffer at the buffer * start. If this would exceed the total buffer headroom the kernel will * panic. A pointer to the first byte of the extra data is returned. */ unsigned char *skb_push(struct sk_buff *skb, unsigned int len) { skb->data -= len; skb->len += len; if (unlikely(skb->data<skb->head)) skb_under_panic(skb, len, __builtin_return_address(0)); return skb->data; } EXPORT_SYMBOL(skb_push); /** * skb_pull - remove data from the start of a buffer * @skb: buffer to use * @len: amount of data to remove * * This function removes data from the start of a buffer, returning * the memory to the headroom. A pointer to the next data in the buffer * is returned. Once the data has been pulled future pushes will overwrite * the old data. */ unsigned char *skb_pull(struct sk_buff *skb, unsigned int len) { return unlikely(len > skb->len) ? NULL : __skb_pull(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_shinfo(skb)->frags[i].size; if (end < len) { offset = end; continue; } skb_shinfo(skb)->frags[i++].size = len - offset; drop_pages: skb_shinfo(skb)->nr_frags = i; for (; i < nfrags; i++) put_page(skb_shinfo(skb)->frags[i].page); if (skb_shinfo(skb)->frag_list) 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; kfree_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); } 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_pointer(skb), 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 { 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)) { 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_pointer(skb); } /* 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; 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; 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; } /* * 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) { struct sk_buff *skb = (struct sk_buff *) spd->partial[i].private; kfree_skb(skb); } /* * Fill page/offset/length into spd, if it can hold more pages. */ static inline int spd_fill_page(struct splice_pipe_desc *spd, struct page *page, unsigned int len, unsigned int offset, struct sk_buff *skb) { if (unlikely(spd->nr_pages == PIPE_BUFFERS)) return 1; spd->pages[spd->nr_pages] = page; spd->partial[spd->nr_pages].len = len; spd->partial[spd->nr_pages].offset = offset; spd->partial[spd->nr_pages].private = (unsigned long) skb_get(skb); spd->nr_pages++; return 0; } /* * Map linear and fragment data from the skb to spd. Returns number of * pages mapped. */ static int __skb_splice_bits(struct sk_buff *skb, unsigned int *offset, unsigned int *total_len, struct splice_pipe_desc *spd) { unsigned int nr_pages = spd->nr_pages; unsigned int poff, plen, len, toff, tlen; int headlen, seg; toff = *offset; tlen = *total_len; if (!tlen) goto err; /* * if the offset is greater than the linear part, go directly to * the fragments. */ headlen = skb_headlen(skb); if (toff >= headlen) { toff -= headlen; goto map_frag; } /* * first map the linear region into the pages/partial map, skipping * any potential initial offset. */ len = 0; while (len < headlen) { void *p = skb->data + len; poff = (unsigned long) p & (PAGE_SIZE - 1); plen = min_t(unsigned int, headlen - len, PAGE_SIZE - poff); len += plen; if (toff) { if (plen <= toff) { toff -= plen; continue; } plen -= toff; poff += toff; toff = 0; } plen = min(plen, tlen); if (!plen) break; /* * just jump directly to update and return, no point * in going over fragments when the output is full. */ if (spd_fill_page(spd, virt_to_page(p), plen, poff, skb)) goto done; tlen -= plen; } /* * then map the fragments */ map_frag: for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) { const skb_frag_t *f = &skb_shinfo(skb)->frags[seg]; plen = f->size; poff = f->page_offset; if (toff) { if (plen <= toff) { toff -= plen; continue; } plen -= toff; poff += toff; toff = 0; } plen = min(plen, tlen); if (!plen) break; if (spd_fill_page(spd, f->page, plen, poff, skb)) break; tlen -= plen; } done: if (spd->nr_pages - nr_pages) { *offset = 0; *total_len = tlen; return 0; } err: return 1; } /* * Map data from the skb to a pipe. Should handle both the linear part, * the fragments, and the frag list. It does NOT handle frag lists within * the frag list, if such a thing exists. We'd probably need to recurse to * handle that cleanly. */ int skb_splice_bits(struct sk_buff *__skb, unsigned int offset, struct pipe_inode_info *pipe, unsigned int tlen, unsigned int flags) { struct partial_page partial[PIPE_BUFFERS]; struct page *pages[PIPE_BUFFERS]; struct splice_pipe_desc spd = { .pages = pages, .partial = partial, .flags = flags, .ops = &sock_pipe_buf_ops, .spd_release = sock_spd_release, }; struct sk_buff *skb; /* * I'd love to avoid the clone here, but tcp_read_sock() * ignores reference counts and unconditonally kills the sk_buff * on return from the actor. */ skb = skb_clone(__skb, GFP_KERNEL); if (unlikely(!skb)) return -ENOMEM; /* * __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(skb, &offset, &tlen, &spd)) goto done; else if (!tlen) goto done; /* * now see if we have a frag_list to map */ if (skb_shinfo(skb)->frag_list) { struct sk_buff *list = skb_shinfo(skb)->frag_list; for (; list && tlen; list = list->next) { if (__skb_splice_bits(list, &offset, &tlen, &spd)) break; } } done: /* * drop our reference to the clone, the pipe consumption will * drop the rest. */ kfree_skb(skb); if (spd.nr_pages) { int ret; /* * Drop the socket lock, otherwise we have reverse * locking dependencies between sk_lock and i_mutex * here as compared to sendfile(). We enter here * with the socket lock held, and splice_to_pipe() will * grab the pipe inode lock. For sendfile() emulation, * we call into ->sendpage() with the i_mutex lock held * and networking will grab the socket lock. */ release_sock(__skb->sk); ret = splice_to_pipe(pipe, &spd); lock_sock(__skb->sk); return ret; } return 0; } /** * 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 i, copy; int start = skb_headlen(skb); 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; BUG_TRAP(start <= offset + len); end = start + frag->size; if ((copy = end - offset) > 0) { u8 *vaddr; if (copy > len) copy = len; vaddr = kmap_skb_frag(frag); memcpy(vaddr + frag->page_offset + offset - start, from, copy); kunmap_skb_frag(vaddr); if ((len -= copy) == 0) return 0; offset += copy; from += 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_store_bits(list, 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) { 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) { __wsum 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) { __wsum 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; } } BUG_ON(len); return csum; } /* 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; 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) { __wsum 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) { __wsum 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; } } BUG_ON(len); return csum; } 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->csum_start - skb_headroom(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); } } /** * 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 * @list: list to use * * Remove a packet from a list. The list locks are taken and this * function is atomic with respect to other list locked calls * * You must know what list the SKB is on. */ void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list) { unsigned long flags; spin_lock_irqsave(&list->lock, flags); __skb_unlink(skb, list); spin_unlock_irqrestore(&list->lock, flags); } /** * skb_append - append a buffer * @old: buffer to insert after * @newsk: buffer to insert * @list: list to use * * 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, struct sk_buff_head *list) { unsigned long flags; spin_lock_irqsave(&list->lock, flags); __skb_queue_after(list, old, newsk); spin_unlock_irqrestore(&list->lock, flags); } /** * skb_insert - insert a buffer * @old: buffer to insert before * @newsk: buffer to insert * @list: list to use * * Place a packet before a given packet in a list. The list locks are * taken and this function is atomic with respect to other list locked * calls. * * A buffer cannot be placed on two lists at the same time. */ void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list) { unsigned long flags; spin_lock_irqsave(&list->lock, flags); __skb_insert(newsk, old->prev, old, list); spin_unlock_irqrestore(&list->lock, flags); } static inline void skb_split_inside_header(struct sk_buff *skb, struct sk_buff* skb1, const u32 len, const int pos) { int i; skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - 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_set_tail_pointer(skb, 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); } /** * skb_prepare_seq_read - Prepare a sequential read of skb data * @skb: the buffer to read * @from: lower offset of data to be read * @to: upper offset of data to be read * @st: state variable * * Initializes the specified state variable. Must be called before * invoking skb_seq_read() for the first time. */ void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from, unsigned int to, struct skb_seq_state *st) { st->lower_offset = from; st->upper_offset = to; st->root_skb = st->cur_skb = skb; st->frag_idx = st->stepped_offset = 0; st->frag_data = NULL; } /** * skb_seq_read - Sequentially read skb data * @consumed: number of bytes consumed by the caller so far * @data: destination pointer for data to be returned * @st: state variable * * Reads a block of skb data at &consumed relative to the * lower offset specified to skb_prepare_seq_read(). Assigns * the head of the data block to &data and returns the length * of the block or 0 if the end of the skb data or the upper * offset has been reached. * * The caller is not required to consume all of the data * returned, i.e. &consumed is typically set to the number * of bytes already consumed and the next call to * skb_seq_read() will return the remaining part of the block. * * Note 1: The size of each block of data returned can be arbitary, * this limitation is the cost for zerocopy seqeuental * reads of potentially non linear data. * * Note 2: Fragment lists within fragments are not implemented * at the moment, state->root_skb could be replaced with * a stack for this purpose. */ unsigned int skb_seq_read(unsigned int consumed, const u8 **data, struct skb_seq_state *st) { unsigned int block_limit, abs_offset = consumed + st->lower_offset; skb_frag_t *frag; if (unlikely(abs_offset >= st->upper_offset)) return 0; next_skb: block_limit = skb_headlen(st->cur_skb); if (abs_offset < block_limit) { *data = st->cur_skb->data + abs_offset; return block_limit - abs_offset; } if (st->frag_idx == 0 && !st->frag_data) st->stepped_offset += skb_headlen(st->cur_skb); while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) { frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx]; block_limit = frag->size + st->stepped_offset; if (abs_offset < block_limit) { if (!st->frag_data) st->frag_data = kmap_skb_frag(frag); *data = (u8 *) st->frag_data + frag->page_offset + (abs_offset - st->stepped_offset); return block_limit - abs_offset; } if (st->frag_data) { kunmap_skb_frag(st->frag_data); st->frag_data = NULL; } st->frag_idx++; st->stepped_offset += frag->size; } if (st->frag_data) { kunmap_skb_frag(st->frag_data); st->frag_data = NULL; } if (st->cur_skb->next) { st->cur_skb = st->cur_skb->next; st->frag_idx = 0; goto next_skb; } else if (st->root_skb == st->cur_skb && skb_shinfo(st->root_skb)->frag_list) { st->cur_skb = skb_shinfo(st->root_skb)->frag_list; goto next_skb; } return 0; } /** * skb_abort_seq_read - Abort a sequential read of skb data * @st: state variable * * Must be called if skb_seq_read() was not called until it * returned 0. */ void skb_abort_seq_read(struct skb_seq_state *st) { if (st->frag_data) kunmap_skb_frag(st->frag_data); } #define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb)) static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text, struct ts_config *conf, struct ts_state *state) { return skb_seq_read(offset, text, TS_SKB_CB(state)); } static void skb_ts_finish(struct ts_config *conf, struct ts_state *state) { skb_abort_seq_read(TS_SKB_CB(state)); } /** * skb_find_text - Find a text pattern in skb data * @skb: the buffer to look in * @from: search offset * @to: search limit * @config: textsearch configuration * @state: uninitialized textsearch state variable * * Finds a pattern in the skb data according to the specified * textsearch configuration. Use textsearch_next() to retrieve * subsequent occurrences of the pattern. Returns the offset * to the first occurrence or UINT_MAX if no match was found. */ unsigned int skb_find_text(struct sk_buff *skb, unsigned int from, unsigned int to, struct ts_config *config, struct ts_state *state) { unsigned int ret; config->get_next_block = skb_ts_get_next_block; config->finish = skb_ts_finish; skb_prepare_seq_read(skb, from, to, TS_SKB_CB(state)); ret = textsearch_find(config, state); return (ret <= to - from ? ret : UINT_MAX); } /** * skb_append_datato_frags: - append the user data to a skb * @sk: sock structure * @skb: skb structure to be appened with user data. * @getfrag: call back function to be used for getting the user data * @from: pointer to user message iov * @length: length of the iov message * * Description: This procedure append the user data in the fragment part * of the skb if any page alloc fails user this procedure returns -ENOMEM */ int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb, int (*getfrag)(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb), void *from, int length) { int frg_cnt = 0; skb_frag_t *frag = NULL; struct page *page = NULL; int copy, left; int offset = 0; int ret; do { /* Return error if we don't have space for new frag */ frg_cnt = skb_shinfo(skb)->nr_frags; if (frg_cnt >= MAX_SKB_FRAGS) return -EFAULT; /* allocate a new page for next frag */ page = alloc_pages(sk->sk_allocation, 0); /* If alloc_page fails just return failure and caller will * free previous allocated pages by doing kfree_skb() */ if (page == NULL) return -ENOMEM; /* initialize the next frag */ sk->sk_sndmsg_page = page; sk->sk_sndmsg_off = 0; skb_fill_page_desc(skb, frg_cnt, page, 0, 0); skb->truesize += PAGE_SIZE; atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc); /* get the new initialized frag */ frg_cnt = skb_shinfo(skb)->nr_frags; frag = &skb_shinfo(skb)->frags[frg_cnt - 1]; /* copy the user data to page */ left = PAGE_SIZE - frag->page_offset; copy = (length > left)? left : length; ret = getfrag(from, (page_address(frag->page) + frag->page_offset + frag->size), offset, copy, 0, skb); if (ret < 0) return -EFAULT; /* copy was successful so update the size parameters */ sk->sk_sndmsg_off += copy; frag->size += copy; skb->len += copy; skb->data_len += copy; offset += copy; length -= copy; } while (length > 0); return 0; } /** * skb_pull_rcsum - pull skb and update receive checksum * @skb: buffer to update * @len: length of data pulled * * This function performs an skb_pull on the packet and updates * the CHECKSUM_COMPLETE checksum. It should be used on * receive path processing instead of skb_pull unless you know * that the checksum difference is zero (e.g., a valid IP header) * or you are setting ip_summed to CHECKSUM_NONE. */ unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len) { BUG_ON(len > skb->len); skb->len -= len; BUG_ON(skb->len < skb->data_len); skb_postpull_rcsum(skb, skb->data, len); return skb->data += len; } EXPORT_SYMBOL_GPL(skb_pull_rcsum); /** * skb_segment - Perform protocol segmentation on skb. * @skb: buffer to segment * @features: features for the output path (see dev->features) * * This function performs segmentation on the given skb. It returns * a pointer to the first in a list of new skbs for the segments. * In case of error it returns ERR_PTR(err). */ struct sk_buff *skb_segment(struct sk_buff *skb, int features) { struct sk_buff *segs = NULL; struct sk_buff *tail = NULL; unsigned int mss = skb_shinfo(skb)->gso_size; unsigned int doffset = skb->data - skb_mac_header(skb); unsigned int offset = doffset; unsigned int headroom; unsigned int len; int sg = features & NETIF_F_SG; int nfrags = skb_shinfo(skb)->nr_frags; int err = -ENOMEM; int i = 0; int pos; __skb_push(skb, doffset); headroom = skb_headroom(skb); pos = skb_headlen(skb); do { struct sk_buff *nskb; skb_frag_t *frag; int hsize; int k; int size; len = skb->len - offset; if (len > mss) len = mss; hsize = skb_headlen(skb) - offset; if (hsize < 0) hsize = 0; if (hsize > len || !sg) hsize = len; nskb = alloc_skb(hsize + doffset + headroom, GFP_ATOMIC); if (unlikely(!nskb)) goto err; if (segs) tail->next = nskb; else segs = nskb; tail = nskb; nskb->dev = skb->dev; skb_copy_queue_mapping(nskb, skb); nskb->priority = skb->priority; nskb->protocol = skb->protocol; nskb->dst = dst_clone(skb->dst); memcpy(nskb->cb, skb->cb, sizeof(skb->cb)); nskb->pkt_type = skb->pkt_type; nskb->mac_len = skb->mac_len; skb_reserve(nskb, headroom); skb_reset_mac_header(nskb); skb_set_network_header(nskb, skb->mac_len); nskb->transport_header = (nskb->network_header + skb_network_header_len(skb)); skb_copy_from_linear_data(skb, skb_put(nskb, doffset), doffset); if (!sg) { nskb->csum = skb_copy_and_csum_bits(skb, offset, skb_put(nskb, len), len, 0); continue; } frag = skb_shinfo(nskb)->frags; k = 0; nskb->ip_summed = CHECKSUM_PARTIAL; nskb->csum = skb->csum; skb_copy_from_linear_data_offset(skb, offset, skb_put(nskb, hsize), hsize); while (pos < offset + len) { BUG_ON(i >= nfrags); *frag = skb_shinfo(skb)->frags[i]; get_page(frag->page); size = frag->size; if (pos < offset) { frag->page_offset += offset - pos; frag->size -= offset - pos; } k++; if (pos + size <= offset + len) { i++; pos += size; } else { frag->size -= pos + size - (offset + len); break; } frag++; } skb_shinfo(nskb)->nr_frags = k; nskb->data_len = len - hsize; nskb->len += nskb->data_len; nskb->truesize += nskb->data_len; } while ((offset += len) < skb->len); return segs; err: while ((skb = segs)) { segs = skb->next; kfree_skb(skb); } return ERR_PTR(err); } EXPORT_SYMBOL_GPL(skb_segment); void __init skb_init(void) { skbuff_head_cache = kmem_cache_create("skbuff_head_cache", sizeof(struct sk_buff), 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache", (2*sizeof(struct sk_buff)) + sizeof(atomic_t), 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); } /** * skb_to_sgvec - Fill a scatter-gather list from a socket buffer * @skb: Socket buffer containing the buffers to be mapped * @sg: The scatter-gather list to map into * @offset: The offset into the buffer's contents to start mapping * @len: Length of buffer space to be mapped * * Fill the specified scatter-gather list with mappings/pointers into a * region of the buffer space attached to a socket buffer. */ static int __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len) { int start = skb_headlen(skb); int i, copy = start - offset; int elt = 0; if (copy > 0) { if (copy > len) copy = len; sg_set_buf(sg, skb->data + offset, copy); elt++; if ((len -= copy) == 0) return elt; offset += 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) { skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; if (copy > len) copy = len; sg_set_page(&sg[elt], frag->page, copy, frag->page_offset+offset-start); elt++; if (!(len -= copy)) return elt; offset += 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; elt += __skb_to_sgvec(list, sg+elt, offset - start, copy); if ((len -= copy) == 0) return elt; offset += copy; } start = end; } } BUG_ON(len); return elt; } int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len) { int nsg = __skb_to_sgvec(skb, sg, offset, len); sg_mark_end(&sg[nsg - 1]); return nsg; } /** * skb_cow_data - Check that a socket buffer's data buffers are writable * @skb: The socket buffer to check. * @tailbits: Amount of trailing space to be added * @trailer: Returned pointer to the skb where the @tailbits space begins * * Make sure that the data buffers attached to a socket buffer are * writable. If they are not, private copies are made of the data buffers * and the socket buffer is set to use these instead. * * If @tailbits is given, make sure that there is space to write @tailbits * bytes of data beyond current end of socket buffer. @trailer will be * set to point to the skb in which this space begins. * * The number of scatterlist elements required to completely map the * COW'd and extended socket buffer will be returned. */ int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer) { int copyflag; int elt; struct sk_buff *skb1, **skb_p; /* If skb is cloned or its head is paged, reallocate * head pulling out all the pages (pages are considered not writable * at the moment even if they are anonymous). */ if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) && __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL) return -ENOMEM; /* Easy case. Most of packets will go this way. */ if (!skb_shinfo(skb)->frag_list) { /* A little of trouble, not enough of space for trailer. * This should not happen, when stack is tuned to generate * good frames. OK, on miss we reallocate and reserve even more * space, 128 bytes is fair. */ if (skb_tailroom(skb) < tailbits && pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC)) return -ENOMEM; /* Voila! */ *trailer = skb; return 1; } /* Misery. We are in troubles, going to mincer fragments... */ elt = 1; skb_p = &skb_shinfo(skb)->frag_list; copyflag = 0; while ((skb1 = *skb_p) != NULL) { int ntail = 0; /* The fragment is partially pulled by someone, * this can happen on input. Copy it and everything * after it. */ if (skb_shared(skb1)) copyflag = 1; /* If the skb is the last, worry about trailer. */ if (skb1->next == NULL && tailbits) { if (skb_shinfo(skb1)->nr_frags || skb_shinfo(skb1)->frag_list || skb_tailroom(skb1) < tailbits) ntail = tailbits + 128; } if (copyflag || skb_cloned(skb1) || ntail || skb_shinfo(skb1)->nr_frags || skb_shinfo(skb1)->frag_list) { struct sk_buff *skb2; /* Fuck, we are miserable poor guys... */ if (ntail == 0) skb2 = skb_copy(skb1, GFP_ATOMIC); else skb2 = skb_copy_expand(skb1, skb_headroom(skb1), ntail, GFP_ATOMIC); if (unlikely(skb2 == NULL)) return -ENOMEM; if (skb1->sk) skb_set_owner_w(skb2, skb1->sk); /* Looking around. Are we still alive? * OK, link new skb, drop old one */ skb2->next = skb1->next; *skb_p = skb2; kfree_skb(skb1); skb1 = skb2; } elt++; *trailer = skb1; skb_p = &skb1->next; } return elt; } /** * skb_partial_csum_set - set up and verify partial csum values for packet * @skb: the skb to set * @start: the number of bytes after skb->data to start checksumming. * @off: the offset from start to place the checksum. * * For untrusted partially-checksummed packets, we need to make sure the values * for skb->csum_start and skb->csum_offset are valid so we don't oops. * * This function checks and sets those values and skb->ip_summed: if this * returns false you should drop the packet. */ bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off) { if (unlikely(start > skb->len - 2) || unlikely((int)start + off > skb->len - 2)) { if (net_ratelimit()) printk(KERN_WARNING "bad partial csum: csum=%u/%u len=%u\n", start, off, skb->len); return false; } skb->ip_summed = CHECKSUM_PARTIAL; skb->csum_start = skb_headroom(skb) + start; skb->csum_offset = off; return true; } EXPORT_SYMBOL(___pskb_trim); EXPORT_SYMBOL(__kfree_skb); EXPORT_SYMBOL(kfree_skb); EXPORT_SYMBOL(__pskb_pull_tail); EXPORT_SYMBOL(__alloc_skb); EXPORT_SYMBOL(__netdev_alloc_skb); EXPORT_SYMBOL(pskb_copy); EXPORT_SYMBOL(pskb_expand_head); EXPORT_SYMBOL(skb_checksum); EXPORT_SYMBOL(skb_clone); 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); EXPORT_SYMBOL(skb_prepare_seq_read); EXPORT_SYMBOL(skb_seq_read); EXPORT_SYMBOL(skb_abort_seq_read); EXPORT_SYMBOL(skb_find_text); EXPORT_SYMBOL(skb_append_datato_frags); EXPORT_SYMBOL_GPL(skb_to_sgvec); EXPORT_SYMBOL_GPL(skb_cow_data); EXPORT_SYMBOL_GPL(skb_partial_csum_set);