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