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![Florian Westphal](/assets/img/avatar_default.png)
When a netnsamespace exits, the nf_tables pernet_ops will remove all rules.
However, there is one caveat:
Base chains that register ingress hooks will cause use-after-free:
device is already gone at that point.
The device event handlers prevent this from happening:
netns exit synthesizes unregister events for all devices.
However, an improper fix for a race condition made the notifiers a no-op
in case they get called from netns exit path, so revert that part.
This is safe now as the previous patch fixed nf_tables pernet ops
and device notifier initialisation ordering.
Fixes: 0a2cf5ee43
("netfilter: nf_tables: close race between netns exit and rmmod")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
405 lines
9.8 KiB
C
405 lines
9.8 KiB
C
#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/netdevice.h>
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#include <net/net_namespace.h>
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#include <net/netfilter/nf_tables.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/netfilter_ipv6.h>
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#include <linux/netfilter_bridge.h>
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#include <linux/netfilter_arp.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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#ifdef CONFIG_NF_TABLES_IPV4
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static unsigned int nft_do_chain_ipv4(void *priv,
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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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struct nft_pktinfo pkt;
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nft_set_pktinfo(&pkt, skb, state);
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nft_set_pktinfo_ipv4(&pkt, skb);
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return nft_do_chain(&pkt, priv);
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}
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static const struct nft_chain_type nft_chain_filter_ipv4 = {
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.name = "filter",
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.type = NFT_CHAIN_T_DEFAULT,
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.family = NFPROTO_IPV4,
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.hook_mask = (1 << NF_INET_LOCAL_IN) |
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(1 << NF_INET_LOCAL_OUT) |
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(1 << NF_INET_FORWARD) |
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(1 << NF_INET_PRE_ROUTING) |
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(1 << NF_INET_POST_ROUTING),
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.hooks = {
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[NF_INET_LOCAL_IN] = nft_do_chain_ipv4,
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[NF_INET_LOCAL_OUT] = nft_do_chain_ipv4,
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[NF_INET_FORWARD] = nft_do_chain_ipv4,
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[NF_INET_PRE_ROUTING] = nft_do_chain_ipv4,
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[NF_INET_POST_ROUTING] = nft_do_chain_ipv4,
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},
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};
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static void nft_chain_filter_ipv4_init(void)
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{
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nft_register_chain_type(&nft_chain_filter_ipv4);
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}
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static void nft_chain_filter_ipv4_fini(void)
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{
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nft_unregister_chain_type(&nft_chain_filter_ipv4);
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}
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#else
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static inline void nft_chain_filter_ipv4_init(void) {}
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static inline void nft_chain_filter_ipv4_fini(void) {}
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#endif /* CONFIG_NF_TABLES_IPV4 */
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#ifdef CONFIG_NF_TABLES_ARP
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static unsigned int nft_do_chain_arp(void *priv, 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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nft_set_pktinfo(&pkt, skb, state);
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nft_set_pktinfo_unspec(&pkt, skb);
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return nft_do_chain(&pkt, priv);
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}
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static const struct nft_chain_type nft_chain_filter_arp = {
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.name = "filter",
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.type = NFT_CHAIN_T_DEFAULT,
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.family = NFPROTO_ARP,
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.owner = THIS_MODULE,
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.hook_mask = (1 << NF_ARP_IN) |
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(1 << NF_ARP_OUT),
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.hooks = {
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[NF_ARP_IN] = nft_do_chain_arp,
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[NF_ARP_OUT] = nft_do_chain_arp,
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},
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};
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static void nft_chain_filter_arp_init(void)
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{
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nft_register_chain_type(&nft_chain_filter_arp);
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}
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static void nft_chain_filter_arp_fini(void)
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{
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nft_unregister_chain_type(&nft_chain_filter_arp);
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}
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#else
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static inline void nft_chain_filter_arp_init(void) {}
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static inline void nft_chain_filter_arp_fini(void) {}
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#endif /* CONFIG_NF_TABLES_ARP */
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#ifdef CONFIG_NF_TABLES_IPV6
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static unsigned int nft_do_chain_ipv6(void *priv,
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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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struct nft_pktinfo pkt;
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nft_set_pktinfo(&pkt, skb, state);
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nft_set_pktinfo_ipv6(&pkt, skb);
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return nft_do_chain(&pkt, priv);
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}
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static const struct nft_chain_type nft_chain_filter_ipv6 = {
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.name = "filter",
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.type = NFT_CHAIN_T_DEFAULT,
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.family = NFPROTO_IPV6,
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.hook_mask = (1 << NF_INET_LOCAL_IN) |
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(1 << NF_INET_LOCAL_OUT) |
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(1 << NF_INET_FORWARD) |
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(1 << NF_INET_PRE_ROUTING) |
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(1 << NF_INET_POST_ROUTING),
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.hooks = {
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[NF_INET_LOCAL_IN] = nft_do_chain_ipv6,
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[NF_INET_LOCAL_OUT] = nft_do_chain_ipv6,
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[NF_INET_FORWARD] = nft_do_chain_ipv6,
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[NF_INET_PRE_ROUTING] = nft_do_chain_ipv6,
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[NF_INET_POST_ROUTING] = nft_do_chain_ipv6,
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},
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};
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static void nft_chain_filter_ipv6_init(void)
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{
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nft_register_chain_type(&nft_chain_filter_ipv6);
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}
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static void nft_chain_filter_ipv6_fini(void)
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{
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nft_unregister_chain_type(&nft_chain_filter_ipv6);
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}
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#else
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static inline void nft_chain_filter_ipv6_init(void) {}
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static inline void nft_chain_filter_ipv6_fini(void) {}
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#endif /* CONFIG_NF_TABLES_IPV6 */
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#ifdef CONFIG_NF_TABLES_INET
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static unsigned int nft_do_chain_inet(void *priv, 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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nft_set_pktinfo(&pkt, skb, state);
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switch (state->pf) {
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case NFPROTO_IPV4:
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nft_set_pktinfo_ipv4(&pkt, skb);
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break;
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case NFPROTO_IPV6:
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nft_set_pktinfo_ipv6(&pkt, skb);
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break;
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default:
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break;
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}
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return nft_do_chain(&pkt, priv);
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}
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static const struct nft_chain_type nft_chain_filter_inet = {
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.name = "filter",
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.type = NFT_CHAIN_T_DEFAULT,
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.family = NFPROTO_INET,
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.hook_mask = (1 << NF_INET_LOCAL_IN) |
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(1 << NF_INET_LOCAL_OUT) |
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(1 << NF_INET_FORWARD) |
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(1 << NF_INET_PRE_ROUTING) |
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(1 << NF_INET_POST_ROUTING),
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.hooks = {
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[NF_INET_LOCAL_IN] = nft_do_chain_inet,
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[NF_INET_LOCAL_OUT] = nft_do_chain_inet,
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[NF_INET_FORWARD] = nft_do_chain_inet,
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[NF_INET_PRE_ROUTING] = nft_do_chain_inet,
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[NF_INET_POST_ROUTING] = nft_do_chain_inet,
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},
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};
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static void nft_chain_filter_inet_init(void)
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{
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nft_register_chain_type(&nft_chain_filter_inet);
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}
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static void nft_chain_filter_inet_fini(void)
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{
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nft_unregister_chain_type(&nft_chain_filter_inet);
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}
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#else
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static inline void nft_chain_filter_inet_init(void) {}
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static inline void nft_chain_filter_inet_fini(void) {}
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#endif /* CONFIG_NF_TABLES_IPV6 */
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#ifdef CONFIG_NF_TABLES_BRIDGE
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static unsigned int
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nft_do_chain_bridge(void *priv,
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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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struct nft_pktinfo pkt;
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nft_set_pktinfo(&pkt, skb, state);
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switch (eth_hdr(skb)->h_proto) {
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case htons(ETH_P_IP):
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nft_set_pktinfo_ipv4_validate(&pkt, skb);
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break;
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case htons(ETH_P_IPV6):
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nft_set_pktinfo_ipv6_validate(&pkt, skb);
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break;
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default:
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nft_set_pktinfo_unspec(&pkt, skb);
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break;
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}
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return nft_do_chain(&pkt, priv);
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}
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static const struct nft_chain_type nft_chain_filter_bridge = {
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.name = "filter",
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.type = NFT_CHAIN_T_DEFAULT,
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.family = NFPROTO_BRIDGE,
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.hook_mask = (1 << NF_BR_PRE_ROUTING) |
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(1 << NF_BR_LOCAL_IN) |
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(1 << NF_BR_FORWARD) |
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(1 << NF_BR_LOCAL_OUT) |
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(1 << NF_BR_POST_ROUTING),
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.hooks = {
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[NF_BR_PRE_ROUTING] = nft_do_chain_bridge,
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[NF_BR_LOCAL_IN] = nft_do_chain_bridge,
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[NF_BR_FORWARD] = nft_do_chain_bridge,
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[NF_BR_LOCAL_OUT] = nft_do_chain_bridge,
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[NF_BR_POST_ROUTING] = nft_do_chain_bridge,
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},
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};
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static void nft_chain_filter_bridge_init(void)
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{
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nft_register_chain_type(&nft_chain_filter_bridge);
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}
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static void nft_chain_filter_bridge_fini(void)
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{
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nft_unregister_chain_type(&nft_chain_filter_bridge);
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}
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#else
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static inline void nft_chain_filter_bridge_init(void) {}
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static inline void nft_chain_filter_bridge_fini(void) {}
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#endif /* CONFIG_NF_TABLES_BRIDGE */
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#ifdef CONFIG_NF_TABLES_NETDEV
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static unsigned int nft_do_chain_netdev(void *priv, 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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nft_set_pktinfo(&pkt, skb, state);
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switch (skb->protocol) {
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case htons(ETH_P_IP):
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nft_set_pktinfo_ipv4_validate(&pkt, skb);
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break;
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case htons(ETH_P_IPV6):
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nft_set_pktinfo_ipv6_validate(&pkt, skb);
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break;
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default:
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nft_set_pktinfo_unspec(&pkt, skb);
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break;
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}
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return nft_do_chain(&pkt, priv);
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}
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static const struct nft_chain_type nft_chain_filter_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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.hook_mask = (1 << NF_NETDEV_INGRESS),
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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 void nft_netdev_event(unsigned long event, struct net_device *dev,
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struct nft_ctx *ctx)
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{
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struct nft_base_chain *basechain = nft_base_chain(ctx->chain);
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switch (event) {
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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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/* UNREGISTER events are also happpening on netns exit.
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*
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* Altough nf_tables core releases all tables/chains, only
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* this event handler provides guarantee that
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* basechain.ops->dev is still accessible, so we cannot
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* skip exiting net namespaces.
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*/
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__nft_release_basechain(ctx);
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break;
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case NETDEV_CHANGENAME:
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if (dev->ifindex != basechain->ops.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_table *table;
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struct nft_chain *chain, *nr;
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struct nft_ctx ctx = {
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.net = dev_net(dev),
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};
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if (event != NETDEV_UNREGISTER &&
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event != NETDEV_CHANGENAME)
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return NOTIFY_DONE;
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mutex_lock(&ctx.net->nft.commit_mutex);
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list_for_each_entry(table, &ctx.net->nft.tables, list) {
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if (table->family != NFPROTO_NETDEV)
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continue;
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ctx.family = table->family;
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ctx.table = table;
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list_for_each_entry_safe(chain, nr, &table->chains, list) {
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if (!nft_is_base_chain(chain))
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continue;
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ctx.chain = chain;
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nft_netdev_event(event, dev, &ctx);
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}
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}
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mutex_unlock(&ctx.net->nft.commit_mutex);
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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 nft_chain_filter_netdev_init(void)
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{
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int err;
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nft_register_chain_type(&nft_chain_filter_netdev);
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err = register_netdevice_notifier(&nf_tables_netdev_notifier);
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if (err)
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goto err_register_netdevice_notifier;
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return 0;
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err_register_netdevice_notifier:
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nft_unregister_chain_type(&nft_chain_filter_netdev);
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return err;
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}
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static void nft_chain_filter_netdev_fini(void)
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{
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nft_unregister_chain_type(&nft_chain_filter_netdev);
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unregister_netdevice_notifier(&nf_tables_netdev_notifier);
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}
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#else
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static inline int nft_chain_filter_netdev_init(void) { return 0; }
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static inline void nft_chain_filter_netdev_fini(void) {}
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#endif /* CONFIG_NF_TABLES_NETDEV */
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int __init nft_chain_filter_init(void)
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{
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int err;
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err = nft_chain_filter_netdev_init();
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if (err < 0)
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return err;
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nft_chain_filter_ipv4_init();
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nft_chain_filter_ipv6_init();
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nft_chain_filter_arp_init();
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nft_chain_filter_inet_init();
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nft_chain_filter_bridge_init();
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return 0;
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}
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void nft_chain_filter_fini(void)
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{
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nft_chain_filter_bridge_fini();
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nft_chain_filter_inet_fini();
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nft_chain_filter_arp_fini();
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nft_chain_filter_ipv6_fini();
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nft_chain_filter_ipv4_fini();
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nft_chain_filter_netdev_fini();
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}
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