/* * 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 __read_mostly; static kmem_cache_t *skbuff_fclone_cache __read_mostly; /* * 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:%p end:%p dev:%s\n", here, skb->len, sz, skb->head, skb->data, skb->tail, 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:%p end:%p dev:%s\n", here, skb->len, sz, skb->head, skb->data, skb->tail, skb->end, 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 * @fclone: allocate from fclone cache instead of head cache * and allocate a cloned (child) skb * * 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) { struct sk_buff *skb; u8 *data; /* Get the HEAD */ if (fclone) skb = kmem_cache_alloc(skbuff_fclone_cache, gfp_mask & ~__GFP_DMA); else 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; 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; } 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; skb_shinfo(skb)->ufo_size = 0; skb_shinfo(skb)->ip6_frag_id = 0; 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, gfp_t 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) { struct sk_buff *other; atomic_t *fclone_ref; skb_release_data(skb); 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; }; } /** * __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) { dst_release(skb->dst); #ifdef CONFIG_XFRM secpath_put(skb->sp); #endif if (skb->destructor) { WARN_ON(in_irq()); 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; #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, 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; } #define C(x) n->x = skb->x n->next = n->prev = NULL; n->sk = NULL; C(tstamp); C(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); n->destructor = NULL; #ifdef CONFIG_NETFILTER C(nfmark); C(nfct); nf_conntrack_get(skb->nfct); C(nfctinfo); #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) C(ipvs_property); #endif #ifdef CONFIG_BRIDGE_NETFILTER C(nf_bridge); nf_bridge_get(skb->nf_bridge); #endif #endif /*CONFIG_NETFILTER*/ #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(n->tc_verd); n->tc_verd = CLR_TC_MUNGED(n->tc_verd); C(input_dev); #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->sk = NULL; new->dev = old->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->fclone = SKB_FCLONE_UNAVAILABLE; new->pkt_type = old->pkt_type; new->tstamp = old->tstamp; new->destructor = NULL; #ifdef CONFIG_NETFILTER new->nfmark = old->nfmark; new->nfct = old->nfct; nf_conntrack_get(old->nfct); new->nfctinfo = old->nfctinfo; #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) new->ipvs_property = old->ipvs_property; #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, gfp_t 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, gfp_t 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, gfp_t 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, gfp_t 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; } /** * 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(const struct sk_buff *skb, int offset, 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; memcpy(skb->data + 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. */ 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 * @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_append(old, newsk, list); 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); } #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); } /** * 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: 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: 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->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) { 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)); return textsearch_find(config, state); } /** * 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; } 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"); skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache", (2*sizeof(struct sk_buff)) + sizeof(atomic_t), 0, SLAB_HWCACHE_ALIGN, NULL, NULL); if (!skbuff_fclone_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); 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);