#include <linux/kernel.h>#include <linux/slab.h>#include <linux/init.h>#include <linux/module.h>#include <linux/proc_fs.h>#include <linux/skbuff.h>#include <linux/netfilter.h>#include <linux/seq_file.h>#include <linux/rcupdate.h>#include <net/protocol.h>#include <net/netfilter/nf_queue.h>#include <net/dst.h> #include "nf_internals.h" /* * Hook for nfnetlink_queue to register its queue handler. * We do this so that most of the NFQUEUE code can be modular. * * Once the queue is registered it must reinject all packets it * receives, no matter what. */static const struct nf_queue_handler __rcu *queue_handler __read_mostly; /* return EBUSY when somebody else is registered, return EEXIST if the * same handler is registered, return 0 in case of success. */void nf_register_queue_handler(const struct nf_queue_handler *qh){	/* should never happen, we only have one queueing backend in kernel */	WARN_ON(rcu_access_pointer(queue_handler));	rcu_assign_pointer(queue_handler, qh);}EXPORT_SYMBOL(nf_register_queue_handler); /* The caller must flush their queue before this */void nf_unregister_queue_handler(void){	RCU_INIT_POINTER(queue_handler, NULL);	synchronize_rcu();}EXPORT_SYMBOL(nf_unregister_queue_handler); static void nf_queue_entry_release_refs(struct nf_queue_entry *entry){	/* Release those devices we held, or Alexey will kill me. */	if (entry->indev)		dev_put(entry->indev);	if (entry->outdev)		dev_put(entry->outdev);#ifdef CONFIG_BRIDGE_NETFILTER	if (entry->skb->nf_bridge) {		struct nf_bridge_info *nf_bridge = entry->skb->nf_bridge; 		if (nf_bridge->physindev)			dev_put(nf_bridge->physindev);		if (nf_bridge->physoutdev)			dev_put(nf_bridge->physoutdev);	}#endif	/* Drop reference to owner of hook which queued us. */	module_put(entry->elem->owner);} /* * Any packet that leaves via this function must come back * through nf_reinject(). */static int __nf_queue(struct sk_buff *skb,		      struct nf_hook_ops *elem,		      u_int8_t pf, unsigned int hook,		      struct net_device *indev,		      struct net_device *outdev,		      int (*okfn)(struct sk_buff *),		      unsigned int queuenum){	int status = -ENOENT;	struct nf_queue_entry *entry = NULL;#ifdef CONFIG_BRIDGE_NETFILTER	struct net_device *physindev;	struct net_device *physoutdev;#endif	const struct nf_afinfo *afinfo;	const struct nf_queue_handler *qh; 	/* QUEUE == DROP if no one is waiting, to be safe. */	rcu_read_lock(); 	qh = rcu_dereference(queue_handler);	if (!qh) {		status = -ESRCH;		goto err_unlock;	} 	afinfo = nf_get_afinfo(pf);	if (!afinfo)		goto err_unlock; 	entry = kmalloc(sizeof(*entry) + afinfo->route_key_size, GFP_ATOMIC);	if (!entry) {		status = -ENOMEM;		goto err_unlock;	} 	*entry = (struct nf_queue_entry) {		.skb	= skb,		.elem	= elem,		.pf	= pf,		.hook	= hook,		.indev	= indev,		.outdev	= outdev,		.okfn	= okfn,	}; 	/* If it's going away, ignore hook. */	if (!try_module_get(entry->elem->owner)) {		status = -ECANCELED;		goto err_unlock;	}	/* Bump dev refs so they don't vanish while packet is out */	if (indev)		dev_hold(indev);	if (outdev)		dev_hold(outdev);#ifdef CONFIG_BRIDGE_NETFILTER	if (skb->nf_bridge) {		physindev = skb->nf_bridge->physindev;		if (physindev)			dev_hold(physindev);		physoutdev = skb->nf_bridge->physoutdev;		if (physoutdev)			dev_hold(physoutdev);	}#endif	skb_dst_force(skb);	afinfo->saveroute(skb, entry);	status = qh->outfn(entry, queuenum); 	rcu_read_unlock(); 	if (status < 0) {		nf_queue_entry_release_refs(entry);		goto err;	} 	return 0; err_unlock:	rcu_read_unlock();err:	kfree(entry);	return status;} #ifdef CONFIG_BRIDGE_NETFILTER/* When called from bridge netfilter, skb->data must point to MAC header * before calling skb_gso_segment(). Else, original MAC header is lost * and segmented skbs will be sent to wrong destination. */static void nf_bridge_adjust_skb_data(struct sk_buff *skb){	if (skb->nf_bridge)		__skb_push(skb, skb->network_header - skb->mac_header);} static void nf_bridge_adjust_segmented_data(struct sk_buff *skb){	if (skb->nf_bridge)		__skb_pull(skb, skb->network_header - skb->mac_header);}#else#define nf_bridge_adjust_skb_data(s) do {} while (0)#define nf_bridge_adjust_segmented_data(s) do {} while (0)#endif int nf_queue(struct sk_buff *skb,	     struct nf_hook_ops *elem,	     u_int8_t pf, unsigned int hook,	     struct net_device *indev,	     struct net_device *outdev,	     int (*okfn)(struct sk_buff *),	     unsigned int queuenum){	struct sk_buff *segs;	int err = -EINVAL;	unsigned int queued; 	if (!skb_is_gso(skb))		return __nf_queue(skb, elem, pf, hook, indev, outdev, okfn,				  queuenum); 	switch (pf) {	case NFPROTO_IPV4:		skb->protocol = htons(ETH_P_IP);		break;	case NFPROTO_IPV6:		skb->protocol = htons(ETH_P_IPV6);		break;	} 	nf_bridge_adjust_skb_data(skb);	segs = skb_gso_segment(skb, 0);	/* Does not use PTR_ERR to limit the number of error codes that can be	 * returned by nf_queue.  For instance, callers rely on -ECANCELED to mean	 * 'ignore this hook'.	 */	if (IS_ERR(segs))		goto out_err;	queued = 0;	err = 0;	do {		struct sk_buff *nskb = segs->next; 		segs->next = NULL;		if (err == 0) {			nf_bridge_adjust_segmented_data(segs);			err = __nf_queue(segs, elem, pf, hook, indev,					   outdev, okfn, queuenum);		}		if (err == 0)			queued++;		else			kfree_skb(segs);		segs = nskb;	} while (segs); 	if (queued) {		kfree_skb(skb);		return 0;	}  out_err:	nf_bridge_adjust_segmented_data(skb);	return err;} void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict){	struct sk_buff *skb = entry->skb;	struct nf_hook_ops *elem = entry->elem;	const struct nf_afinfo *afinfo;	int err; 	rcu_read_lock(); 	nf_queue_entry_release_refs(entry); 	/* Continue traversal iff userspace said ok... */	if (verdict == NF_REPEAT) {		elem = list_entry(elem->list.prev, struct nf_hook_ops, list);		verdict = NF_ACCEPT;	} 	if (verdict == NF_ACCEPT) {		afinfo = nf_get_afinfo(entry->pf);		if (!afinfo || afinfo->reroute(skb, entry) < 0)			verdict = NF_DROP;	} 	if (verdict == NF_ACCEPT) {	next_hook:		verdict = nf_iterate(&nf_hooks[entry->pf][entry->hook],				     skb, entry->hook,				     entry->indev, entry->outdev, &elem,				     entry->okfn, INT_MIN);	} 	switch (verdict & NF_VERDICT_MASK) {	case NF_ACCEPT:	case NF_STOP:		local_bh_disable();		entry->okfn(skb);		local_bh_enable();		break;	case NF_QUEUE:		err = __nf_queue(skb, elem, entry->pf, entry->hook,				 entry->indev, entry->outdev, entry->okfn,				 verdict >> NF_VERDICT_QBITS);		if (err < 0) {			if (err == -ECANCELED)				goto next_hook;			if (err == -ESRCH &&			   (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS))				goto next_hook;			kfree_skb(skb);		}		break;	case NF_STOLEN:		break;	default:		kfree_skb(skb);	}	rcu_read_unlock();	kfree(entry);}EXPORT_SYMBOL(nf_reinject);