![Pablo Neira Ayuso](/assets/img/avatar_default.png)
In case the net_device is gone, we have to unregister the hooks and put back the reference on the net_device object. Once it comes back, register them again. This also covers the device rename case. This patch also adds a new flag to indicate that the basechain is disabled, so their hooks are not registered. This flag is used by the netdev family to handle the case where the net_device object is gone. Currently this flag is not exposed to userspace. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
259 lines
6.2 KiB
C
259 lines
6.2 KiB
C
/*
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* Copyright (c) 2015 Pablo Neira Ayuso <pablo@netfilter.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/netdevice.h>
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#include <net/netfilter/nf_tables.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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#include <net/netfilter/nf_tables_ipv4.h>
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#include <net/netfilter/nf_tables_ipv6.h>
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static inline void
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nft_netdev_set_pktinfo_ipv4(struct nft_pktinfo *pkt,
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const struct nf_hook_ops *ops, struct sk_buff *skb,
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const struct nf_hook_state *state)
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{
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struct iphdr *iph, _iph;
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u32 len, thoff;
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nft_set_pktinfo(pkt, ops, skb, state);
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iph = skb_header_pointer(skb, skb_network_offset(skb), sizeof(*iph),
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&_iph);
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if (!iph)
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return;
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iph = ip_hdr(skb);
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if (iph->ihl < 5 || iph->version != 4)
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return;
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len = ntohs(iph->tot_len);
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thoff = iph->ihl * 4;
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if (skb->len < len)
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return;
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else if (len < thoff)
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return;
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pkt->tprot = iph->protocol;
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pkt->xt.thoff = thoff;
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pkt->xt.fragoff = ntohs(iph->frag_off) & IP_OFFSET;
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}
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static inline void
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__nft_netdev_set_pktinfo_ipv6(struct nft_pktinfo *pkt,
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const struct nf_hook_ops *ops,
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struct sk_buff *skb,
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const struct nf_hook_state *state)
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{
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#if IS_ENABLED(CONFIG_IPV6)
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struct ipv6hdr *ip6h, _ip6h;
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unsigned int thoff = 0;
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unsigned short frag_off;
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int protohdr;
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u32 pkt_len;
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ip6h = skb_header_pointer(skb, skb_network_offset(skb), sizeof(*ip6h),
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&_ip6h);
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if (!ip6h)
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return;
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if (ip6h->version != 6)
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return;
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pkt_len = ntohs(ip6h->payload_len);
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if (pkt_len + sizeof(*ip6h) > skb->len)
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return;
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protohdr = ipv6_find_hdr(pkt->skb, &thoff, -1, &frag_off, NULL);
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if (protohdr < 0)
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return;
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pkt->tprot = protohdr;
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pkt->xt.thoff = thoff;
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pkt->xt.fragoff = frag_off;
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#endif
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}
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static inline void nft_netdev_set_pktinfo_ipv6(struct nft_pktinfo *pkt,
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const struct nf_hook_ops *ops,
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struct sk_buff *skb,
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const struct nf_hook_state *state)
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{
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nft_set_pktinfo(pkt, ops, skb, state);
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__nft_netdev_set_pktinfo_ipv6(pkt, ops, skb, state);
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}
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static unsigned int
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nft_do_chain_netdev(const struct nf_hook_ops *ops, struct sk_buff *skb,
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const struct nf_hook_state *state)
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{
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struct nft_pktinfo pkt;
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switch (eth_hdr(skb)->h_proto) {
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case htons(ETH_P_IP):
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nft_netdev_set_pktinfo_ipv4(&pkt, ops, skb, state);
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break;
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case htons(ETH_P_IPV6):
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nft_netdev_set_pktinfo_ipv6(&pkt, ops, skb, state);
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break;
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default:
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nft_set_pktinfo(&pkt, ops, skb, state);
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break;
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}
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return nft_do_chain(&pkt, ops);
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}
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static struct nft_af_info nft_af_netdev __read_mostly = {
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.family = NFPROTO_NETDEV,
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.nhooks = NF_NETDEV_NUMHOOKS,
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.owner = THIS_MODULE,
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.flags = NFT_AF_NEEDS_DEV,
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.nops = 1,
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.hooks = {
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[NF_NETDEV_INGRESS] = nft_do_chain_netdev,
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},
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};
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static int nf_tables_netdev_init_net(struct net *net)
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{
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net->nft.netdev = kmalloc(sizeof(struct nft_af_info), GFP_KERNEL);
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if (net->nft.netdev == NULL)
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return -ENOMEM;
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memcpy(net->nft.netdev, &nft_af_netdev, sizeof(nft_af_netdev));
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if (nft_register_afinfo(net, net->nft.netdev) < 0)
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goto err;
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return 0;
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err:
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kfree(net->nft.netdev);
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return -ENOMEM;
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}
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static void nf_tables_netdev_exit_net(struct net *net)
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{
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nft_unregister_afinfo(net->nft.netdev);
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kfree(net->nft.netdev);
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}
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static struct pernet_operations nf_tables_netdev_net_ops = {
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.init = nf_tables_netdev_init_net,
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.exit = nf_tables_netdev_exit_net,
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};
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static const struct nf_chain_type nft_filter_chain_netdev = {
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.name = "filter",
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.type = NFT_CHAIN_T_DEFAULT,
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.family = NFPROTO_NETDEV,
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.owner = THIS_MODULE,
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.hook_mask = (1 << NF_NETDEV_INGRESS),
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};
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static void nft_netdev_event(unsigned long event, struct nft_af_info *afi,
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struct net_device *dev, struct nft_table *table,
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struct nft_base_chain *basechain)
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{
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switch (event) {
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case NETDEV_REGISTER:
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if (strcmp(basechain->dev_name, dev->name) != 0)
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return;
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BUG_ON(!(basechain->flags & NFT_BASECHAIN_DISABLED));
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dev_hold(dev);
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basechain->ops[0].dev = dev;
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basechain->flags &= ~NFT_BASECHAIN_DISABLED;
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if (!(table->flags & NFT_TABLE_F_DORMANT))
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nft_register_basechain(basechain, afi->nops);
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break;
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case NETDEV_UNREGISTER:
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if (strcmp(basechain->dev_name, dev->name) != 0)
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return;
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BUG_ON(basechain->flags & NFT_BASECHAIN_DISABLED);
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if (!(table->flags & NFT_TABLE_F_DORMANT))
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nft_unregister_basechain(basechain, afi->nops);
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dev_put(basechain->ops[0].dev);
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basechain->ops[0].dev = NULL;
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basechain->flags |= NFT_BASECHAIN_DISABLED;
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break;
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case NETDEV_CHANGENAME:
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if (dev->ifindex != basechain->ops[0].dev->ifindex)
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return;
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strncpy(basechain->dev_name, dev->name, IFNAMSIZ);
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break;
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}
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}
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static int nf_tables_netdev_event(struct notifier_block *this,
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unsigned long event, void *ptr)
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{
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struct net_device *dev = netdev_notifier_info_to_dev(ptr);
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struct nft_af_info *afi;
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struct nft_table *table;
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struct nft_chain *chain;
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nfnl_lock(NFNL_SUBSYS_NFTABLES);
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list_for_each_entry(afi, &dev_net(dev)->nft.af_info, list) {
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if (afi->family != NFPROTO_NETDEV)
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continue;
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list_for_each_entry(table, &afi->tables, list) {
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list_for_each_entry(chain, &table->chains, list) {
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if (!(chain->flags & NFT_BASE_CHAIN))
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continue;
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nft_netdev_event(event, afi, dev, table,
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nft_base_chain(chain));
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}
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}
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}
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nfnl_unlock(NFNL_SUBSYS_NFTABLES);
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return NOTIFY_DONE;
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}
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static struct notifier_block nf_tables_netdev_notifier = {
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.notifier_call = nf_tables_netdev_event,
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};
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static int __init nf_tables_netdev_init(void)
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{
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int ret;
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nft_register_chain_type(&nft_filter_chain_netdev);
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ret = register_pernet_subsys(&nf_tables_netdev_net_ops);
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if (ret < 0)
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nft_unregister_chain_type(&nft_filter_chain_netdev);
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register_netdevice_notifier(&nf_tables_netdev_notifier);
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return ret;
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}
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static void __exit nf_tables_netdev_exit(void)
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{
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unregister_netdevice_notifier(&nf_tables_netdev_notifier);
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unregister_pernet_subsys(&nf_tables_netdev_net_ops);
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nft_unregister_chain_type(&nft_filter_chain_netdev);
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}
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module_init(nf_tables_netdev_init);
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module_exit(nf_tables_netdev_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
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MODULE_ALIAS_NFT_FAMILY(5); /* NFPROTO_NETDEV */
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