*** empty log message ***

2 files changed, 1862 insertions, 0 deletions

diff --git a/br-nf-bds/linux2.5/net/core/netfilter.c b/br-nf-bds/linux2.5/net/core/netfilter.c
new file mode 100644
index 0000000..198dad6
--- /dev/null
+++ b/br-nf-bds/linux2.5/net/core/netfilter.c
@@ -0,0 +1,654 @@
+/* netfilter.c: look after the filters for various protocols. 
+ * Heavily influenced by the old firewall.c by David Bonn and Alan Cox.
+ *
+ * Thanks to Rob `CmdrTaco' Malda for not influencing this code in any
+ * way.
+ *
+ * Rusty Russell (C)2000 -- This code is GPL.
+ *
+ * February 2000: Modified by James Morris to have 1 queue per protocol.
+ * 15-Mar-2000:   Added NF_REPEAT --RR.
+ */
+#include <linux/config.h>
+#include <linux/netfilter.h>
+#include <net/protocol.h>
+#include <linux/init.h>
+#include <linux/skbuff.h>
+#include <linux/wait.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/if.h>
+#include <linux/netdevice.h>
+#include <linux/brlock.h>
+#include <linux/inetdevice.h>
+#include <net/sock.h>
+#include <net/route.h>
+#include <linux/ip.h>
+
+#define __KERNEL_SYSCALLS__
+#include <linux/unistd.h>
+
+/* In this code, we can be waiting indefinitely for userspace to
+ * service a packet if a hook returns NF_QUEUE.  We could keep a count
+ * of skbuffs queued for userspace, and not deregister a hook unless
+ * this is zero, but that sucks.  Now, we simply check when the
+ * packets come back: if the hook is gone, the packet is discarded. */
+#ifdef CONFIG_NETFILTER_DEBUG
+#define NFDEBUG(format, args...)  printk(format , ## args)
+#else
+#define NFDEBUG(format, args...)
+#endif
+
+/* Sockopts only registered and called from user context, so
+   BR_NETPROTO_LOCK would be overkill.  Also, [gs]etsockopt calls may
+   sleep. */
+static DECLARE_MUTEX(nf_sockopt_mutex);
+
+struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS];
+static LIST_HEAD(nf_sockopts);
+
+/* 
+ * A queue handler may be registered for each protocol.  Each is protected by
+ * long term mutex.  The handler must provide an an outfn() to accept packets
+ * for queueing and must reinject all packets it receives, no matter what.
+ */
+static struct nf_queue_handler_t {
+	nf_queue_outfn_t outfn;
+	void *data;
+} queue_handler[NPROTO];
+
+int nf_register_hook(struct nf_hook_ops *reg)
+{
+	struct list_head *i;
+
+	br_write_lock_bh(BR_NETPROTO_LOCK);
+	for (i = nf_hooks[reg->pf][reg->hooknum].next; 
+	     i != &nf_hooks[reg->pf][reg->hooknum]; 
+	     i = i->next) {
+		if (reg->priority < ((struct nf_hook_ops *)i)->priority)
+			break;
+	}
+	list_add(&reg->list, i->prev);
+	br_write_unlock_bh(BR_NETPROTO_LOCK);
+	return 0;
+}
+
+void nf_unregister_hook(struct nf_hook_ops *reg)
+{
+	br_write_lock_bh(BR_NETPROTO_LOCK);
+	list_del(&reg->list);
+	br_write_unlock_bh(BR_NETPROTO_LOCK);
+}
+
+/* Do exclusive ranges overlap? */
+static inline int overlap(int min1, int max1, int min2, int max2)
+{
+	return max1 > min2 && min1 < max2;
+}
+
+/* Functions to register sockopt ranges (exclusive). */
+int nf_register_sockopt(struct nf_sockopt_ops *reg)
+{
+	struct list_head *i;
+	int ret = 0;
+
+	if (down_interruptible(&nf_sockopt_mutex) != 0)
+		return -EINTR;
+
+	for (i = nf_sockopts.next; i != &nf_sockopts; i = i->next) {
+		struct nf_sockopt_ops *ops = (struct nf_sockopt_ops *)i;
+		if (ops->pf == reg->pf
+		    && (overlap(ops->set_optmin, ops->set_optmax, 
+				reg->set_optmin, reg->set_optmax)
+			|| overlap(ops->get_optmin, ops->get_optmax, 
+				   reg->get_optmin, reg->get_optmax))) {
+			NFDEBUG("nf_sock overlap: %u-%u/%u-%u v %u-%u/%u-%u\n",
+				ops->set_optmin, ops->set_optmax, 
+				ops->get_optmin, ops->get_optmax, 
+				reg->set_optmin, reg->set_optmax,
+				reg->get_optmin, reg->get_optmax);
+			ret = -EBUSY;
+			goto out;
+		}
+	}
+
+	list_add(&reg->list, &nf_sockopts);
+out:
+	up(&nf_sockopt_mutex);
+	return ret;
+}
+
+void nf_unregister_sockopt(struct nf_sockopt_ops *reg)
+{
+	/* No point being interruptible: we're probably in cleanup_module() */
+ restart:
+	down(&nf_sockopt_mutex);
+	if (reg->use != 0) {
+		/* To be woken by nf_sockopt call... */
+		/* FIXME: Stuart Young's name appears gratuitously. */
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		reg->cleanup_task = current;
+		up(&nf_sockopt_mutex);
+		schedule();
+		goto restart;
+	}
+	list_del(&reg->list);
+	up(&nf_sockopt_mutex);
+}
+
+#ifdef CONFIG_NETFILTER_DEBUG
+#include <net/ip.h>
+#include <net/route.h>
+#include <net/tcp.h>
+#include <linux/netfilter_ipv4.h>
+
+static void debug_print_hooks_ip(unsigned int nf_debug)
+{
+	if (nf_debug & (1 << NF_IP_PRE_ROUTING)) {
+		printk("PRE_ROUTING ");
+		nf_debug ^= (1 << NF_IP_PRE_ROUTING);
+	}
+	if (nf_debug & (1 << NF_IP_LOCAL_IN)) {
+		printk("LOCAL_IN ");
+		nf_debug ^= (1 << NF_IP_LOCAL_IN);
+	}
+	if (nf_debug & (1 << NF_IP_FORWARD)) {
+		printk("FORWARD ");
+		nf_debug ^= (1 << NF_IP_FORWARD);
+	}
+	if (nf_debug & (1 << NF_IP_LOCAL_OUT)) {
+		printk("LOCAL_OUT ");
+		nf_debug ^= (1 << NF_IP_LOCAL_OUT);
+	}
+	if (nf_debug & (1 << NF_IP_POST_ROUTING)) {
+		printk("POST_ROUTING ");
+		nf_debug ^= (1 << NF_IP_POST_ROUTING);
+	}
+	if (nf_debug)
+		printk("Crap bits: 0x%04X", nf_debug);
+	printk("\n");
+}
+
+void nf_dump_skb(int pf, struct sk_buff *skb)
+{
+	printk("skb: pf=%i %s dev=%s len=%u\n", 
+	       pf,
+	       skb->sk ? "(owned)" : "(unowned)",
+	       skb->dev ? skb->dev->name : "(no dev)",
+	       skb->len);
+	switch (pf) {
+	case PF_INET: {
+		const struct iphdr *ip = skb->nh.iph;
+		__u32 *opt = (__u32 *) (ip + 1);
+		int opti;
+		__u16 src_port = 0, dst_port = 0;
+
+		if (ip->protocol == IPPROTO_TCP
+		    || ip->protocol == IPPROTO_UDP) {
+			struct tcphdr *tcp=(struct tcphdr *)((__u32 *)ip+ip->ihl);
+			src_port = ntohs(tcp->source);
+			dst_port = ntohs(tcp->dest);
+		}
+	
+		printk("PROTO=%d %u.%u.%u.%u:%hu %u.%u.%u.%u:%hu"
+		       " L=%hu S=0x%2.2hX I=%hu F=0x%4.4hX T=%hu",
+		       ip->protocol, NIPQUAD(ip->saddr),
+		       src_port, NIPQUAD(ip->daddr),
+		       dst_port,
+		       ntohs(ip->tot_len), ip->tos, ntohs(ip->id),
+		       ntohs(ip->frag_off), ip->ttl);
+
+		for (opti = 0; opti < (ip->ihl - sizeof(struct iphdr) / 4); opti++)
+			printk(" O=0x%8.8X", *opt++);
+		printk("\n");
+	}
+	}
+}
+
+void nf_debug_ip_local_deliver(struct sk_buff *skb)
+{
+	/* If it's a loopback packet, it must have come through
+	 * NF_IP_LOCAL_OUT, NF_IP_RAW_INPUT, NF_IP_PRE_ROUTING and
+	 * NF_IP_LOCAL_IN.  Otherwise, must have gone through
+	 * NF_IP_RAW_INPUT and NF_IP_PRE_ROUTING.  */
+	if (!skb->dev) {
+		printk("ip_local_deliver: skb->dev is NULL.\n");
+	}
+	else if (strcmp(skb->dev->name, "lo") == 0) {
+		if (skb->nf_debug != ((1 << NF_IP_LOCAL_OUT)
+				      | (1 << NF_IP_POST_ROUTING)
+				      | (1 << NF_IP_PRE_ROUTING)
+				      | (1 << NF_IP_LOCAL_IN))) {
+			printk("ip_local_deliver: bad loopback skb: ");
+			debug_print_hooks_ip(skb->nf_debug);
+			nf_dump_skb(PF_INET, skb);
+		}
+	}
+	else {
+		if (skb->nf_debug != ((1<<NF_IP_PRE_ROUTING)
+				      | (1<<NF_IP_LOCAL_IN))) {
+			printk("ip_local_deliver: bad non-lo skb: ");
+			debug_print_hooks_ip(skb->nf_debug);
+			nf_dump_skb(PF_INET, skb);
+		}
+	}
+}
+
+void nf_debug_ip_loopback_xmit(struct sk_buff *newskb)
+{
+	if (newskb->nf_debug != ((1 << NF_IP_LOCAL_OUT)
+				 | (1 << NF_IP_POST_ROUTING))) {
+		printk("ip_dev_loopback_xmit: bad owned skb = %p: ", 
+		       newskb);
+		debug_print_hooks_ip(newskb->nf_debug);
+		nf_dump_skb(PF_INET, newskb);
+	}
+	/* Clear to avoid confusing input check */
+	newskb->nf_debug = 0;
+}
+
+void nf_debug_ip_finish_output2(struct sk_buff *skb)
+{
+	/* If it's owned, it must have gone through the
+	 * NF_IP_LOCAL_OUT and NF_IP_POST_ROUTING.
+	 * Otherwise, must have gone through
+	 * NF_IP_PRE_ROUTING, NF_IP_FORWARD and NF_IP_POST_ROUTING.
+	 */
+	if (skb->sk) {
+		if (skb->nf_debug != ((1 << NF_IP_LOCAL_OUT)
+				      | (1 << NF_IP_POST_ROUTING))) {
+			printk("ip_finish_output: bad owned skb = %p: ", skb);
+			debug_print_hooks_ip(skb->nf_debug);
+			nf_dump_skb(PF_INET, skb);
+		}
+	} else {
+		if (skb->nf_debug != ((1 << NF_IP_PRE_ROUTING)
+				      | (1 << NF_IP_FORWARD)
+				      | (1 << NF_IP_POST_ROUTING))) {
+			/* Fragments, entunnelled packets, TCP RSTs
+                           generated by ipt_REJECT will have no
+                           owners, but still may be local */
+			if (skb->nf_debug != ((1 << NF_IP_LOCAL_OUT)
+					      | (1 << NF_IP_POST_ROUTING))){
+				printk("ip_finish_output:"
+				       " bad unowned skb = %p: ",skb);
+				debug_print_hooks_ip(skb->nf_debug);
+				nf_dump_skb(PF_INET, skb);
+			}
+		}
+	}
+}
+#endif /*CONFIG_NETFILTER_DEBUG*/
+
+/* Call get/setsockopt() */
+static int nf_sockopt(struct sock *sk, int pf, int val, 
+		      char *opt, int *len, int get)
+{
+	struct list_head *i;
+	struct nf_sockopt_ops *ops;
+	int ret;
+
+	if (down_interruptible(&nf_sockopt_mutex) != 0)
+		return -EINTR;
+
+	for (i = nf_sockopts.next; i != &nf_sockopts; i = i->next) {
+		ops = (struct nf_sockopt_ops *)i;
+		if (ops->pf == pf) {
+			if (get) {
+				if (val >= ops->get_optmin
+				    && val < ops->get_optmax) {
+					ops->use++;
+					up(&nf_sockopt_mutex);
+					ret = ops->get(sk, val, opt, len);
+					goto out;
+				}
+			} else {
+				if (val >= ops->set_optmin
+				    && val < ops->set_optmax) {
+					ops->use++;
+					up(&nf_sockopt_mutex);
+					ret = ops->set(sk, val, opt, *len);
+					goto out;
+				}
+			}
+		}
+	}
+	up(&nf_sockopt_mutex);
+	return -ENOPROTOOPT;
+	
+ out:
+	down(&nf_sockopt_mutex);
+	ops->use--;
+	if (ops->cleanup_task)
+		wake_up_process(ops->cleanup_task);
+	up(&nf_sockopt_mutex);
+	return ret;
+}
+
+int nf_setsockopt(struct sock *sk, int pf, int val, char *opt,
+		  int len)
+{
+	return nf_sockopt(sk, pf, val, opt, &len, 0);
+}
+
+int nf_getsockopt(struct sock *sk, int pf, int val, char *opt, int *len)
+{
+	return nf_sockopt(sk, pf, val, opt, len, 1);
+}
+
+static unsigned int nf_iterate(struct list_head *head,
+			       struct sk_buff **skb,
+			       int hook,
+			       const struct net_device *indev,
+			       const struct net_device *outdev,
+			       struct list_head **i,
+			       int (*okfn)(struct sk_buff *),
+			       int hook_thresh)
+{
+	for (*i = (*i)->next; *i != head; *i = (*i)->next) {
+		struct nf_hook_ops *elem = (struct nf_hook_ops *)*i;
+
+		if (hook_thresh > elem->priority)
+			continue;
+
+		switch (elem->hook(hook, skb, indev, outdev, okfn)) {
+		case NF_QUEUE:
+			return NF_QUEUE;
+
+		case NF_STOLEN:
+			return NF_STOLEN;
+
+		case NF_DROP:
+			return NF_DROP;
+
+		case NF_REPEAT:
+			*i = (*i)->prev;
+			break;
+
+#ifdef CONFIG_NETFILTER_DEBUG
+		case NF_ACCEPT:
+			break;
+
+		default:
+			NFDEBUG("Evil return from %p(%u).\n", 
+				elem->hook, hook);
+#endif
+		}
+	}
+	return NF_ACCEPT;
+}
+
+int nf_register_queue_handler(int pf, nf_queue_outfn_t outfn, void *data)
+{      
+	int ret;
+
+	br_write_lock_bh(BR_NETPROTO_LOCK);
+	if (queue_handler[pf].outfn)
+		ret = -EBUSY;
+	else {
+		queue_handler[pf].outfn = outfn;
+		queue_handler[pf].data = data;
+		ret = 0;
+	}
+	br_write_unlock_bh(BR_NETPROTO_LOCK);
+
+	return ret;
+}
+
+/* The caller must flush their queue before this */
+int nf_unregister_queue_handler(int pf)
+{
+	br_write_lock_bh(BR_NETPROTO_LOCK);
+	queue_handler[pf].outfn = NULL;
+	queue_handler[pf].data = NULL;
+	br_write_unlock_bh(BR_NETPROTO_LOCK);
+	return 0;
+}
+
+/* 
+ * Any packet that leaves via this function must come back 
+ * through nf_reinject().
+ */
+static void nf_queue(struct sk_buff *skb, 
+		     struct list_head *elem, 
+		     int pf, unsigned int hook,
+		     struct net_device *indev,
+		     struct net_device *outdev,
+		     int (*okfn)(struct sk_buff *))
+{
+	int status;
+	struct nf_info *info;
+	struct net_device *physindev;
+	struct net_device *physoutdev;
+
+	if (!queue_handler[pf].outfn) {
+		kfree_skb(skb);
+		return;
+	}
+
+	info = kmalloc(sizeof(*info), GFP_ATOMIC);
+	if (!info) {
+		if (net_ratelimit())
+			printk(KERN_ERR "OOM queueing packet %p\n",
+			       skb);
+		kfree_skb(skb);
+		return;
+	}
+
+	*info = (struct nf_info) { 
+		(struct nf_hook_ops *)elem, pf, hook, indev, outdev, okfn };
+
+	/* Bump dev refs so they don't vanish while packet is out */
+	if (indev) dev_hold(indev);
+	if (outdev) dev_hold(outdev);
+
+	if ((physindev = skb->physindev)) dev_hold(physindev);
+	if ((physoutdev = skb->physoutdev)) dev_hold(physoutdev);
+
+	status = queue_handler[pf].outfn(skb, info, queue_handler[pf].data);
+	if (status < 0) {
+		/* James M doesn't say fuck enough. */
+		if (indev) dev_put(indev);
+		if (outdev) dev_put(outdev);
+		if (physindev) dev_put(physindev);
+		if (physoutdev) dev_put(physoutdev);
+		kfree(info);
+		kfree_skb(skb);
+		return;
+	}
+}
+
+int nf_hook_slow(int pf, unsigned int hook, struct sk_buff *skb,
+		 struct net_device *indev,
+		 struct net_device *outdev,
+		 int (*okfn)(struct sk_buff *),
+		 int hook_thresh)
+{
+	struct list_head *elem;
+	unsigned int verdict;
+	int ret = 0;
+
+	/* This stopgap cannot be removed until all the hooks are audited. */
+	if (skb_is_nonlinear(skb) && skb_linearize(skb, GFP_ATOMIC) != 0) {
+		kfree_skb(skb);
+		return -ENOMEM;
+	}
+	if (skb->ip_summed == CHECKSUM_HW) {
+		if (outdev == NULL) {
+			skb->ip_summed = CHECKSUM_NONE;
+		} else {
+			skb_checksum_help(skb);
+		}
+	}
+
+	/* We may already have this, but read-locks nest anyway */
+	br_read_lock_bh(BR_NETPROTO_LOCK);
+
+#ifdef CONFIG_NETFILTER_DEBUG
+	if (skb->nf_debug & (1 << hook)) {
+		printk("nf_hook: hook %i already set.\n", hook);
+		nf_dump_skb(pf, skb);
+	}
+	skb->nf_debug |= (1 << hook);
+#endif
+
+	elem = &nf_hooks[pf][hook];
+	verdict = nf_iterate(&nf_hooks[pf][hook], &skb, hook, indev,
+			     outdev, &elem, okfn, hook_thresh);
+	if (verdict == NF_QUEUE) {
+		NFDEBUG("nf_hook: Verdict = QUEUE.\n");
+		nf_queue(skb, elem, pf, hook, indev, outdev, okfn);
+	}
+
+	switch (verdict) {
+	case NF_ACCEPT:
+		ret = okfn(skb);
+		break;
+
+	case NF_DROP:
+		kfree_skb(skb);
+		ret = -EPERM;
+		break;
+	}
+
+	br_read_unlock_bh(BR_NETPROTO_LOCK);
+	return ret;
+}
+
+void nf_reinject(struct sk_buff *skb, struct nf_info *info,
+		 unsigned int verdict)
+{
+	struct list_head *elem = &info->elem->list;
+	struct list_head *i;
+
+	/* We don't have BR_NETPROTO_LOCK here */
+	br_read_lock_bh(BR_NETPROTO_LOCK);
+	for (i = nf_hooks[info->pf][info->hook].next; i != elem; i = i->next) {
+		if (i == &nf_hooks[info->pf][info->hook]) {
+			/* The module which sent it to userspace is gone. */
+			NFDEBUG("%s: module disappeared, dropping packet.\n",
+			         __FUNCTION__);
+			verdict = NF_DROP;
+			break;
+		}
+	}
+
+	/* Continue traversal iff userspace said ok... */
+	if (verdict == NF_REPEAT) {
+		elem = elem->prev;
+		verdict = NF_ACCEPT;
+	}
+
+	if (verdict == NF_ACCEPT) {
+		verdict = nf_iterate(&nf_hooks[info->pf][info->hook],
+				     &skb, info->hook, 
+				     info->indev, info->outdev, &elem,
+				     info->okfn, INT_MIN);
+	}
+
+	switch (verdict) {
+	case NF_ACCEPT:
+		info->okfn(skb);
+		break;
+
+	case NF_QUEUE:
+		nf_queue(skb, elem, info->pf, info->hook, 
+			 info->indev, info->outdev, info->okfn);
+		break;
+
+	case NF_DROP:
+		kfree_skb(skb);
+		break;
+	}
+	br_read_unlock_bh(BR_NETPROTO_LOCK);
+
+	/* Release those devices we held, or Alexey will kill me. */
+	if (info->indev) dev_put(info->indev);
+	if (info->outdev) dev_put(info->outdev);
+	
+	kfree(info);
+	return;
+}
+
+#ifdef CONFIG_INET
+/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
+int ip_route_me_harder(struct sk_buff **pskb)
+{
+	struct iphdr *iph = (*pskb)->nh.iph;
+	struct rtable *rt;
+	struct rt_key key = { dst:iph->daddr,
+			      src:iph->saddr,
+			      oif:(*pskb)->sk ? (*pskb)->sk->bound_dev_if : 0,
+			      tos:RT_TOS(iph->tos)|RTO_CONN,
+#ifdef CONFIG_IP_ROUTE_FWMARK
+			      fwmark:(*pskb)->nfmark
+#endif
+			    };
+	struct net_device *dev_src = NULL;
+	int err;
+
+	/* accomodate ip_route_output_slow(), which expects the key src to be
+	   0 or a local address; however some non-standard hacks like
+	   ipt_REJECT.c:send_reset() can cause packets with foreign
+           saddr to be appear on the NF_IP_LOCAL_OUT hook -MB */
+	if(key.src && !(dev_src = ip_dev_find(key.src)))
+		key.src = 0;
+
+	if ((err=ip_route_output_key(&rt, &key)) != 0) {
+		printk("route_me_harder: ip_route_output_key(dst=%u.%u.%u.%u, src=%u.%u.%u.%u, oif=%d, tos=0x%x, fwmark=0x%lx) error %d\n",
+			NIPQUAD(iph->daddr), NIPQUAD(iph->saddr),
+			(*pskb)->sk ? (*pskb)->sk->bound_dev_if : 0,
+			RT_TOS(iph->tos)|RTO_CONN,
+#ifdef CONFIG_IP_ROUTE_FWMARK
+			(*pskb)->nfmark,
+#else
+			0UL,
+#endif
+			err);
+		goto out;
+	}
+
+	/* Drop old route. */
+	dst_release((*pskb)->dst);
+
+	(*pskb)->dst = &rt->u.dst;
+
+	/* Change in oif may mean change in hh_len. */
+	if (skb_headroom(*pskb) < (*pskb)->dst->dev->hard_header_len) {
+		struct sk_buff *nskb;
+
+		nskb = skb_realloc_headroom(*pskb,
+					    (*pskb)->dst->dev->hard_header_len);
+		if (!nskb) {
+			err = -ENOMEM;
+			goto out;
+		}
+		if ((*pskb)->sk)
+			skb_set_owner_w(nskb, (*pskb)->sk);
+		kfree_skb(*pskb);
+		*pskb = nskb;
+	}
+
+out:
+	if (dev_src)
+		dev_put(dev_src);
+
+	return err;
+}
+#endif /*CONFIG_INET*/
+
+/* This does not belong here, but ipt_REJECT needs it if connection
+   tracking in use: without this, connection may not be in hash table,
+   and hence manufactured ICMP or RST packets will not be associated
+   with it. */
+void (*ip_ct_attach)(struct sk_buff *, struct nf_ct_info *);
+
+void __init netfilter_init(void)
+{
+	int i, h;
+
+	for (i = 0; i < NPROTO; i++) {
+		for (h = 0; h < NF_MAX_HOOKS; h++)
+			INIT_LIST_HEAD(&nf_hooks[i][h]);
+	}
+}
diff --git a/br-nf-bds/linux2.5/net/core/skbuff.c b/br-nf-bds/linux2.5/net/core/skbuff.c
new file mode 100644
index 0000000..eecc16e
--- /dev/null
+++ b/br-nf-bds/linux2.5/net/core/skbuff.c
@@ -0,0 +1,1208 @@
+/*
+ *	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 1.1 2002/08/24 09:27:04 bdschuym 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.
+ *
+ *	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/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>
+#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 <asm/uaccess.h>
+#include <asm/system.h>
+
+int sysctl_hot_list_len = 128;
+
+static kmem_cache_t *skbuff_head_cache;
+
+static union {
+	struct sk_buff_head	list;
+	char			pad[SMP_CACHE_BYTES];
+} skb_head_pool[NR_CPUS];
+
+/*
+ *	Keep out-of-line to prevent kernel bloat.
+ *	__builtin_return_address is not used because it is not always
+ *	reliable.
+ */
+
+/**
+ *	skb_over_panic	- 	private function
+ *	@skb: buffer
+ *	@sz: size
+ *	@here: address
+ *
+ *	Out of line support code for skb_put(). Not user callable.
+ */
+void skb_over_panic(struct sk_buff *skb, int sz, void *here)
+{
+	printk(KERN_INFO "skput:over: %p:%d put:%d dev:%s",
+		here, skb->len, sz, skb->dev ? skb->dev->name : "<NULL>");
+	BUG();
+}
+
+/**
+ *	skb_under_panic	- 	private function
+ *	@skb: buffer
+ *	@sz: size
+ *	@here: address
+ *
+ *	Out of line support code for skb_push(). Not user callable.
+ */
+
+void skb_under_panic(struct sk_buff *skb, int sz, void *here)
+{
+	printk(KERN_INFO "skput:under: %p:%d put:%d dev:%s",
+               here, skb->len, sz, skb->dev ? skb->dev->name : "<NULL>");
+	BUG();
+}
+
+static __inline__ struct sk_buff *skb_head_from_pool(void)
+{
+	struct sk_buff_head *list;
+	struct sk_buff *skb = NULL;
+	unsigned long flags;
+
+	local_irq_save(flags);
+
+	list = &skb_head_pool[smp_processor_id()].list;
+
+	if (skb_queue_len(list))
+		skb = __skb_dequeue(list);
+
+	local_irq_restore(flags);
+	return skb;
+}
+
+static __inline__ void skb_head_to_pool(struct sk_buff *skb)
+{
+	struct sk_buff_head *list;
+	unsigned long flags;
+
+	local_irq_save(flags);
+
+	list = &skb_head_pool[smp_processor_id()].list;
+
+	if (skb_queue_len(list) < sysctl_hot_list_len) {
+		__skb_queue_head(list, skb);
+		local_irq_restore(flags);
+
+		return;
+	}
+
+	local_irq_restore(flags);
+	kmem_cache_free(skbuff_head_cache, skb);
+}
+
+
+/* 	Allocate a new skbuff. We do this ourselves so we can fill in a few
+ *	'private' fields and also do memory statistics to find all the
+ *	[BEEP] leaks.
+ *
+ */
+
+/**
+ *	alloc_skb	-	allocate a network buffer
+ *	@size: size to allocate
+ *	@gfp_mask: allocation mask
+ *
+ *	Allocate a new &sk_buff. The returned buffer has no headroom and a
+ *	tail room of size bytes. The object has a reference count of one.
+ *	The return is the buffer. On a failure the return is %NULL.
+ *
+ *	Buffers may only be allocated from interrupts using a @gfp_mask of
+ *	%GFP_ATOMIC.
+ */
+struct sk_buff *alloc_skb(unsigned int size, int gfp_mask)
+{
+	struct sk_buff *skb;
+	u8 *data;
+
+	if (in_interrupt() && (gfp_mask & __GFP_WAIT)) {
+		static int count;
+		if (++count < 5) {
+			printk(KERN_ERR "alloc_skb called nonatomically "
+			       "from interrupt %p\n", NET_CALLER(size));
+ 			BUG();
+		}
+		gfp_mask &= ~__GFP_WAIT;
+	}
+
+	/* Get the HEAD */
+	skb = skb_head_from_pool();
+	if (!skb) {
+		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;
+
+	/* XXX: does not include slab overhead */
+	skb->truesize = size + sizeof(struct sk_buff);
+
+	/* Load the data pointers. */
+	skb->head = skb->data = skb->tail = data;
+	skb->end  = data + size;
+
+	/* Set up other state */
+	skb->len      = 0;
+	skb->cloned   = 0;
+	skb->data_len = 0;
+
+	atomic_set(&skb->users, 1);
+	atomic_set(&(skb_shinfo(skb)->dataref), 1);
+	skb_shinfo(skb)->nr_frags  = 0;
+	skb_shinfo(skb)->frag_list = NULL;
+out:
+	return skb;
+nodata:
+	skb_head_to_pool(skb);
+	skb = NULL;
+	goto out;
+}
+
+
+/*
+ *	Slab constructor for a skb head.
+ */
+static inline void skb_headerinit(void *p, kmem_cache_t *cache,
+				  unsigned long flags)
+{
+	struct sk_buff *skb = p;
+
+	skb->next	  = skb->prev = NULL;
+	skb->list	  = NULL;
+	skb->sk		  = NULL;
+	skb->stamp.tv_sec = 0;	/* No idea about time */
+	skb->dev	  = NULL;
+	skb->physindev	  = NULL;
+	skb->physoutdev	  = NULL;
+	skb->dst	  = NULL;
+	memset(skb->cb, 0, sizeof(skb->cb));
+	skb->pkt_type	  = PACKET_HOST;	/* Default type */
+	skb->ip_summed	  = 0;
+	skb->priority	  = 0;
+	skb->security	  = 0;	/* By default packets are insecure */
+	skb->destructor	  = NULL;
+
+#ifdef CONFIG_NETFILTER
+	skb->nfmark	  = skb->nfcache = 0;
+	skb->nfct	  = NULL;
+#ifdef CONFIG_NETFILTER_DEBUG
+	skb->nf_debug	  = 0;
+#endif
+#endif
+#ifdef CONFIG_NET_SCHED
+	skb->tc_index	  = 0;
+#endif
+}
+
+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);
+}
+
+static void skb_release_data(struct sk_buff *skb)
+{
+	if (!skb->cloned ||
+	    atomic_dec_and_test(&(skb_shinfo(skb)->dataref))) {
+		if (skb_shinfo(skb)->nr_frags) {
+			int i;
+			for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
+				put_page(skb_shinfo(skb)->frags[i].page);
+		}
+
+		if (skb_shinfo(skb)->frag_list)
+			skb_drop_fraglist(skb);
+
+		kfree(skb->head);
+	}
+}
+
+/*
+ *	Free an skbuff by memory without cleaning the state.
+ */
+void kfree_skbmem(struct sk_buff *skb)
+{
+	skb_release_data(skb);
+	skb_head_to_pool(skb);
+}
+
+/**
+ *	__kfree_skb - private function
+ *	@skb: buffer
+ *
+ *	Free an sk_buff. Release anything attached to the buffer.
+ *	Clean the state. This is an internal helper function. Users should
+ *	always call kfree_skb
+ */
+
+void __kfree_skb(struct sk_buff *skb)
+{
+	if (skb->list) {
+	 	printk(KERN_WARNING "Warning: kfree_skb passed an skb still "
+		       "on a list (from %p).\n", NET_CALLER(skb));
+		BUG();
+	}
+
+	dst_release(skb->dst);
+	if(skb->destructor) {
+		if (in_irq())
+			printk(KERN_WARNING "Warning: kfree_skb on "
+					    "hard IRQ %p\n", NET_CALLER(skb));
+		skb->destructor(skb);
+	}
+#ifdef CONFIG_NETFILTER
+	nf_conntrack_put(skb->nfct);
+#endif
+	skb_headerinit(skb, NULL, 0);  /* clean state */
+	kfree_skbmem(skb);
+}
+
+/**
+ *	skb_clone	-	duplicate an sk_buff
+ *	@skb: buffer to clone
+ *	@gfp_mask: allocation priority
+ *
+ *	Duplicate an &sk_buff. The new one is not owned by a socket. Both
+ *	copies share the same packet data but not structure. The new
+ *	buffer has a reference count of 1. If the allocation fails the
+ *	function returns %NULL otherwise the new buffer is returned.
+ *
+ *	If this function is called from an interrupt gfp_mask() must be
+ *	%GFP_ATOMIC.
+ */
+
+struct sk_buff *skb_clone(struct sk_buff *skb, int gfp_mask)
+{
+	struct sk_buff *n = skb_head_from_pool();
+
+	if (!n) {
+		n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
+		if (!n)
+			return NULL;
+	}
+
+#define C(x) n->x = skb->x
+
+	n->next = n->prev = NULL;
+	n->list = NULL;
+	n->sk = NULL;
+	C(stamp);
+	C(dev);
+	C(physindev);
+	C(physoutdev);
+	C(physindev);
+	C(physoutdev);
+	C(h);
+	C(nh);
+	C(mac);
+	C(dst);
+	dst_clone(n->dst);
+	memcpy(n->cb, skb->cb, sizeof(skb->cb));
+	C(len);
+	C(data_len);
+	C(csum);
+	n->cloned = 1;
+	C(pkt_type);
+	C(ip_summed);
+	C(priority);
+	atomic_set(&n->users, 1);
+	C(protocol);
+	C(security);
+	C(truesize);
+	C(head);
+	C(data);
+	C(tail);
+	C(end);
+	n->destructor = NULL;
+#ifdef CONFIG_NETFILTER
+	C(nfmark);
+	C(nfcache);
+	C(nfct);
+#ifdef CONFIG_NETFILTER_DEBUG
+	C(nf_debug);
+#endif
+#endif /*CONFIG_NETFILTER*/
+#if defined(CONFIG_HIPPI)
+	C(private);
+#endif
+#ifdef CONFIG_NET_SCHED
+	C(tc_index);
+#endif
+
+	atomic_inc(&(skb_shinfo(skb)->dataref));
+	skb->cloned = 1;
+#ifdef CONFIG_NETFILTER
+	nf_conntrack_get(skb->nfct);
+#endif
+	return n;
+}
+
+static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
+{
+	/*
+	 *	Shift between the two data areas in bytes
+	 */
+	unsigned long offset = new->data - old->data;
+
+	new->list	= NULL;
+	new->sk		= NULL;
+	new->dev	= old->dev;
+	new->physindev	= old->physindev;
+	new->physoutdev	= old->physoutdev;
+	new->priority	= old->priority;
+	new->protocol	= old->protocol;
+	new->dst	= dst_clone(old->dst);
+	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));
+	atomic_set(&new->users, 1);
+	new->pkt_type	= old->pkt_type;
+	new->stamp	= old->stamp;
+	new->destructor = NULL;
+	new->security	= old->security;
+#ifdef CONFIG_NETFILTER
+	new->nfmark	= old->nfmark;
+	new->nfcache	= old->nfcache;
+	new->nfct	= old->nfct;
+	nf_conntrack_get(new->nfct);
+#ifdef CONFIG_NETFILTER_DEBUG
+	new->nf_debug	= old->nf_debug;
+#endif
+#endif
+#ifdef CONFIG_NET_SCHED
+	new->tc_index	= old->tc_index;
+#endif
+}
+
+/**
+ *	skb_copy	-	create private copy of an sk_buff
+ *	@skb: buffer to copy
+ *	@gfp_mask: allocation priority
+ *
+ *	Make a copy of both an &sk_buff and its data. This is used when the
+ *	caller wishes to modify the data and needs a private copy of the
+ *	data to alter. Returns %NULL on failure or the pointer to the buffer
+ *	on success. The returned buffer has a reference count of 1.
+ *
+ *	As by-product this function converts non-linear &sk_buff to linear
+ *	one, so that &sk_buff becomes completely private and caller is allowed
+ *	to modify all the data of returned buffer. This means that this
+ *	function is not recommended for use in circumstances when only
+ *	header is going to be modified. Use pskb_copy() instead.
+ */
+
+struct sk_buff *skb_copy(const struct sk_buff *skb, int gfp_mask)
+{
+	int headerlen = skb->data - skb->head;
+	/*
+	 *	Allocate the copy buffer
+	 */
+	struct sk_buff *n = alloc_skb(skb->end - skb->head + skb->data_len,
+				      gfp_mask);
+	if (!n)
+		return NULL;
+
+	/* Set the data pointer */
+	skb_reserve(n, headerlen);
+	/* Set the tail pointer and length */
+	skb_put(n, skb->len);
+	n->csum	     = skb->csum;
+	n->ip_summed = skb->ip_summed;
+
+	if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
+		BUG();
+
+	copy_skb_header(n, skb);
+	return n;
+}
+
+/* Keep head the same: replace data */
+int skb_linearize(struct sk_buff *skb, int gfp_mask)
+{
+	unsigned int size;
+	u8 *data;
+	long offset;
+	int headerlen = skb->data - skb->head;
+	int expand = (skb->tail + skb->data_len) - skb->end;
+
+	if (skb_shared(skb))
+		BUG();
+
+	if (expand <= 0)
+		expand = 0;
+
+	size = skb->end - skb->head + expand;
+	size = SKB_DATA_ALIGN(size);
+	data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
+	if (!data)
+		return -ENOMEM;
+
+	/* Copy entire thing */
+	if (skb_copy_bits(skb, -headerlen, data, headerlen + skb->len))
+		BUG();
+
+	/* Offset between the two in bytes */
+	offset = data - skb->head;
+
+	/* Free old data. */
+	skb_release_data(skb);
+
+	skb->head = data;
+	skb->end  = data + size;
+
+	/* Set up new pointers */
+	skb->h.raw   += offset;
+	skb->nh.raw  += offset;
+	skb->mac.raw += offset;
+	skb->tail    += offset;
+	skb->data    += offset;
+
+	/* Set up shinfo */
+	atomic_set(&(skb_shinfo(skb)->dataref), 1);
+	skb_shinfo(skb)->nr_frags  = 0;
+	skb_shinfo(skb)->frag_list = NULL;
+
+	/* We are no longer a clone, even if we were. */
+	skb->cloned    = 0;
+
+	skb->tail     += skb->data_len;
+	skb->data_len  = 0;
+	return 0;
+}
+
+
+/**
+ *	pskb_copy	-	create copy of an sk_buff with private head.
+ *	@skb: buffer to copy
+ *	@gfp_mask: allocation priority
+ *
+ *	Make a copy of both an &sk_buff and part of its data, located
+ *	in header. Fragmented data remain shared. This is used when
+ *	the caller wishes to modify only header of &sk_buff and needs
+ *	private copy of the header to alter. Returns %NULL on failure
+ *	or the pointer to the buffer on success.
+ *	The returned buffer has a reference count of 1.
+ */
+
+struct sk_buff *pskb_copy(struct sk_buff *skb, int gfp_mask)
+{
+	/*
+	 *	Allocate the copy buffer
+	 */
+	struct sk_buff *n = alloc_skb(skb->end - skb->head, gfp_mask);
+
+	if (!n)
+		goto out;
+
+	/* Set the data pointer */
+	skb_reserve(n, skb->data - skb->head);
+	/* Set the tail pointer and length */
+	skb_put(n, skb_headlen(skb));
+	/* Copy the bytes */
+	memcpy(n->data, skb->data, n->len);
+	n->csum	     = skb->csum;
+	n->ip_summed = skb->ip_summed;
+
+	n->data_len  = skb->data_len;
+	n->len	     = skb->len;
+
+	if (skb_shinfo(skb)->nr_frags) {
+		int i;
+
+		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+			skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
+			get_page(skb_shinfo(n)->frags[i].page);
+		}
+		skb_shinfo(n)->nr_frags = i;
+	}
+
+	if (skb_shinfo(skb)->frag_list) {
+		skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
+		skb_clone_fraglist(n);
+	}
+
+	copy_skb_header(n, skb);
+out:
+	return n;
+}
+
+/**
+ *	pskb_expand_head - reallocate header of &sk_buff
+ *	@skb: buffer to reallocate
+ *	@nhead: room to add at head
+ *	@ntail: room to add at tail
+ *	@gfp_mask: allocation priority
+ *
+ *	Expands (or creates identical copy, if &nhead and &ntail are zero)
+ *	header of skb. &sk_buff itself is not changed. &sk_buff MUST have
+ *	reference count of 1. Returns zero in the case of success or error,
+ *	if expansion failed. In the last case, &sk_buff is not changed.
+ *
+ *	All the pointers pointing into skb header may change and must be
+ *	reloaded after call to this function.
+ */
+
+int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, int gfp_mask)
+{
+	int i;
+	u8 *data;
+	int size = nhead + (skb->end - skb->head) + ntail;
+	long off;
+
+	if (skb_shared(skb))
+		BUG();
+
+	size = SKB_DATA_ALIGN(size);
+
+	data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
+	if (!data)
+		goto nodata;
+
+	/* Copy only real data... and, alas, header. This should be
+	 * optimized for the cases when header is void. */
+	memcpy(data + nhead, skb->head, skb->tail - skb->head);
+	memcpy(data + size, skb->end, sizeof(struct skb_shared_info));
+
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
+		get_page(skb_shinfo(skb)->frags[i].page);
+
+	if (skb_shinfo(skb)->frag_list)
+		skb_clone_fraglist(skb);
+
+	skb_release_data(skb);
+
+	off = (data + nhead) - skb->head;
+
+	skb->head     = data;
+	skb->end      = data + size;
+	skb->data    += off;
+	skb->tail    += off;
+	skb->mac.raw += off;
+	skb->h.raw   += off;
+	skb->nh.raw  += off;
+	skb->cloned   = 0;
+	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, int gfp_mask)
+{
+	/*
+	 *	Allocate the copy buffer
+	 */
+	struct sk_buff *n = alloc_skb(newheadroom + skb->len + newtailroom,
+				      gfp_mask);
+	if (!n)
+		return NULL;
+
+	skb_reserve(n, newheadroom);
+
+	/* Set the tail pointer and length */
+	skb_put(n, skb->len);
+
+	/* Copy the data only. */
+	if (skb_copy_bits(skb, 0, n->data, skb->len))
+		BUG();
+
+	copy_skb_header(n, skb);
+
+	return n;
+}
+
+/* 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->len - skb->data_len;
+
+	if (offset > (int)skb->len - len)
+		goto fault;
+
+	/* Copy header. */
+	if ((copy = start - offset) > 0) {
+		if (copy > len)
+			copy = len;
+		memcpy(to, skb->data + offset, copy);
+		if ((len -= copy) == 0)
+			return 0;
+		offset += copy;
+		to     += copy;
+	}
+
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		int end;
+
+		BUG_TRAP(start <= offset + len);
+
+		end = start + skb_shinfo(skb)->frags[i].size;
+		if ((copy = end - offset) > 0) {
+			u8 *vaddr;
+
+			if (copy > len)
+				copy = len;
+
+			vaddr = kmap_skb_frag(&skb_shinfo(skb)->frags[i]);
+			memcpy(to,
+			       vaddr + skb_shinfo(skb)->frags[i].page_offset+
+			       offset - start, copy);
+			kunmap_skb_frag(vaddr);
+
+			if ((len -= copy) == 0)
+				return 0;
+			offset += copy;
+			to     += copy;
+		}
+		start = end;
+	}
+
+	if (skb_shinfo(skb)->frag_list) {
+		struct sk_buff *list = skb_shinfo(skb)->frag_list;
+
+		for (; list; list = list->next) {
+			int end;
+
+			BUG_TRAP(start <= offset + len);
+
+			end = start + list->len;
+			if ((copy = end - offset) > 0) {
+				if (copy > len)
+					copy = len;
+				if (skb_copy_bits(list, offset - start,
+						  to, copy))
+					goto fault;
+				if ((len -= copy) == 0)
+					return 0;
+				offset += copy;
+				to     += copy;
+			}
+			start = end;
+		}
+	}
+	if (!len)
+		return 0;
+
+fault:
+	return -EFAULT;
+}
+
+/* Checksum skb data. */
+
+unsigned int skb_checksum(const struct sk_buff *skb, int offset,
+			  int len, unsigned int csum)
+{
+	int start = skb->len - skb->data_len;
+	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->len - skb->data_len;
+	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->len - skb->data_len;
+
+	if (csstart > skb->len - skb->data_len)
+		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);
+	}
+}
+
+#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
+
+void __init skb_init(void)
+{
+	int i;
+
+	skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
+					      sizeof(struct sk_buff),
+					      0,
+					      SLAB_HWCACHE_ALIGN,
+					      skb_headerinit, NULL);
+	if (!skbuff_head_cache)
+		panic("cannot create skbuff cache");
+
+	for (i = 0; i < NR_CPUS; i++)
+		skb_queue_head_init(&skb_head_pool[i].list);
+}