274 lines
6.2 KiB
C
274 lines
6.2 KiB
C
![]() |
#include <linux/config.h>
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#include <linux/kernel.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 <net/protocol.h>
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#include "nf_internals.h"
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/*
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* A queue handler may be registered for each protocol. Each is protected by
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* long term mutex. The handler must provide an an outfn() to accept packets
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* for queueing and must reinject all packets it receives, no matter what.
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*/
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static struct nf_queue_handler_t {
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nf_queue_outfn_t outfn;
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void *data;
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} queue_handler[NPROTO];
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static struct nf_queue_rerouter *queue_rerouter;
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static DEFINE_RWLOCK(queue_handler_lock);
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int nf_register_queue_handler(int pf, nf_queue_outfn_t outfn, void *data)
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{
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int ret;
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if (pf >= NPROTO)
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return -EINVAL;
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write_lock_bh(&queue_handler_lock);
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if (queue_handler[pf].outfn)
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ret = -EBUSY;
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else {
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queue_handler[pf].outfn = outfn;
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queue_handler[pf].data = data;
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ret = 0;
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}
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write_unlock_bh(&queue_handler_lock);
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return ret;
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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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int nf_unregister_queue_handler(int pf)
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{
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if (pf >= NPROTO)
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return -EINVAL;
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write_lock_bh(&queue_handler_lock);
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queue_handler[pf].outfn = NULL;
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queue_handler[pf].data = NULL;
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write_unlock_bh(&queue_handler_lock);
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return 0;
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}
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EXPORT_SYMBOL(nf_unregister_queue_handler);
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int nf_register_queue_rerouter(int pf, struct nf_queue_rerouter *rer)
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{
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if (pf >= NPROTO)
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return -EINVAL;
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write_lock_bh(&queue_handler_lock);
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memcpy(&queue_rerouter[pf], rer, sizeof(queue_rerouter[pf]));
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write_unlock_bh(&queue_handler_lock);
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return 0;
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}
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EXPORT_SYMBOL_GPL(nf_register_queue_rerouter);
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int nf_unregister_queue_rerouter(int pf)
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{
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if (pf >= NPROTO)
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return -EINVAL;
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write_lock_bh(&queue_handler_lock);
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memset(&queue_rerouter[pf], 0, sizeof(queue_rerouter[pf]));
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write_unlock_bh(&queue_handler_lock);
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return 0;
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}
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EXPORT_SYMBOL_GPL(nf_unregister_queue_rerouter);
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void nf_unregister_queue_handlers(nf_queue_outfn_t outfn)
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{
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int pf;
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write_lock_bh(&queue_handler_lock);
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for (pf = 0; pf < NPROTO; pf++) {
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if (queue_handler[pf].outfn == outfn) {
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queue_handler[pf].outfn = NULL;
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queue_handler[pf].data = NULL;
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}
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}
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write_unlock_bh(&queue_handler_lock);
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}
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EXPORT_SYMBOL_GPL(nf_unregister_queue_handlers);
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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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int nf_queue(struct sk_buff **skb,
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struct list_head *elem,
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int 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;
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struct nf_info *info;
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#ifdef CONFIG_BRIDGE_NETFILTER
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struct net_device *physindev = NULL;
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struct net_device *physoutdev = NULL;
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#endif
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/* QUEUE == DROP if noone is waiting, to be safe. */
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read_lock(&queue_handler_lock);
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if (!queue_handler[pf].outfn) {
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read_unlock(&queue_handler_lock);
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kfree_skb(*skb);
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return 1;
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}
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info = kmalloc(sizeof(*info)+queue_rerouter[pf].rer_size, GFP_ATOMIC);
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if (!info) {
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if (net_ratelimit())
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printk(KERN_ERR "OOM queueing packet %p\n",
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*skb);
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read_unlock(&queue_handler_lock);
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kfree_skb(*skb);
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return 1;
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}
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*info = (struct nf_info) {
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(struct nf_hook_ops *)elem, pf, hook, indev, outdev, okfn };
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/* If it's going away, ignore hook. */
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if (!try_module_get(info->elem->owner)) {
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read_unlock(&queue_handler_lock);
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kfree(info);
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return 0;
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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) dev_hold(indev);
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if (outdev) 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) dev_hold(physindev);
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physoutdev = (*skb)->nf_bridge->physoutdev;
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if (physoutdev) dev_hold(physoutdev);
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}
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#endif
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if (queue_rerouter[pf].save)
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queue_rerouter[pf].save(*skb, info);
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status = queue_handler[pf].outfn(*skb, info, queuenum,
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queue_handler[pf].data);
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if (status >= 0 && queue_rerouter[pf].reroute)
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status = queue_rerouter[pf].reroute(skb, info);
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read_unlock(&queue_handler_lock);
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if (status < 0) {
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/* James M doesn't say fuck enough. */
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if (indev) dev_put(indev);
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if (outdev) dev_put(outdev);
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#ifdef CONFIG_BRIDGE_NETFILTER
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if (physindev) dev_put(physindev);
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if (physoutdev) dev_put(physoutdev);
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#endif
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module_put(info->elem->owner);
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kfree(info);
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kfree_skb(*skb);
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return 1;
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}
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return 1;
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}
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void nf_reinject(struct sk_buff *skb, struct nf_info *info,
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unsigned int verdict)
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{
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struct list_head *elem = &info->elem->list;
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struct list_head *i;
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rcu_read_lock();
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/* Release those devices we held, or Alexey will kill me. */
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if (info->indev) dev_put(info->indev);
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if (info->outdev) dev_put(info->outdev);
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#ifdef CONFIG_BRIDGE_NETFILTER
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if (skb->nf_bridge) {
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if (skb->nf_bridge->physindev)
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dev_put(skb->nf_bridge->physindev);
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if (skb->nf_bridge->physoutdev)
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dev_put(skb->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(info->elem->owner);
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list_for_each_rcu(i, &nf_hooks[info->pf][info->hook]) {
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if (i == elem)
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break;
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}
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if (elem == &nf_hooks[info->pf][info->hook]) {
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/* The module which sent it to userspace is gone. */
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NFDEBUG("%s: module disappeared, dropping packet.\n",
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__FUNCTION__);
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verdict = NF_DROP;
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}
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/* Continue traversal iff userspace said ok... */
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if (verdict == NF_REPEAT) {
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elem = elem->prev;
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verdict = NF_ACCEPT;
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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[info->pf][info->hook],
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&skb, info->hook,
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info->indev, info->outdev, &elem,
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info->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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info->okfn(skb);
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break;
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case NF_QUEUE:
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if (!nf_queue(&skb, elem, info->pf, info->hook,
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info->indev, info->outdev, info->okfn,
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verdict >> NF_VERDICT_BITS))
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goto next_hook;
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break;
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}
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rcu_read_unlock();
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if (verdict == NF_DROP)
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kfree_skb(skb);
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kfree(info);
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return;
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}
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EXPORT_SYMBOL(nf_reinject);
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int __init netfilter_queue_init(void)
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{
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queue_rerouter = kmalloc(NPROTO * sizeof(struct nf_queue_rerouter),
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GFP_KERNEL);
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if (!queue_rerouter)
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return -ENOMEM;
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memset(queue_rerouter, 0, NPROTO * sizeof(struct nf_queue_rerouter));
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return 0;
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}
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