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![Phil Sutter](/assets/img/avatar_default.png)
Otherwise packets in egress chains seem like they are being received by
the interface, not sent out via it.
Fixes: 42df6e1d22
("netfilter: Introduce egress hook")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Florian Westphal <fw@strlen.de>
150 lines
4 KiB
C
150 lines
4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _NETFILTER_NETDEV_H_
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#define _NETFILTER_NETDEV_H_
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#include <linux/netfilter.h>
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#include <linux/netdevice.h>
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#ifdef CONFIG_NETFILTER_INGRESS
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static inline bool nf_hook_ingress_active(const struct sk_buff *skb)
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{
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#ifdef CONFIG_JUMP_LABEL
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if (!static_key_false(&nf_hooks_needed[NFPROTO_NETDEV][NF_NETDEV_INGRESS]))
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return false;
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#endif
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return rcu_access_pointer(skb->dev->nf_hooks_ingress);
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}
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/* caller must hold rcu_read_lock */
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static inline int nf_hook_ingress(struct sk_buff *skb)
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{
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struct nf_hook_entries *e = rcu_dereference(skb->dev->nf_hooks_ingress);
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struct nf_hook_state state;
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int ret;
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/* Must recheck the ingress hook head, in the event it became NULL
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* after the check in nf_hook_ingress_active evaluated to true.
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*/
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if (unlikely(!e))
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return 0;
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nf_hook_state_init(&state, NF_NETDEV_INGRESS,
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NFPROTO_NETDEV, skb->dev, NULL, NULL,
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dev_net(skb->dev), NULL);
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ret = nf_hook_slow(skb, &state, e, 0);
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if (ret == 0)
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return -1;
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return ret;
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}
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#else /* CONFIG_NETFILTER_INGRESS */
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static inline int nf_hook_ingress_active(struct sk_buff *skb)
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{
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return 0;
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}
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static inline int nf_hook_ingress(struct sk_buff *skb)
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{
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return 0;
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}
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#endif /* CONFIG_NETFILTER_INGRESS */
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#ifdef CONFIG_NETFILTER_EGRESS
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static inline bool nf_hook_egress_active(void)
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{
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#ifdef CONFIG_JUMP_LABEL
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if (!static_key_false(&nf_hooks_needed[NFPROTO_NETDEV][NF_NETDEV_EGRESS]))
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return false;
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#endif
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return true;
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}
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/**
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* nf_hook_egress - classify packets before transmission
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* @skb: packet to be classified
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* @rc: result code which shall be returned by __dev_queue_xmit() on failure
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* @dev: netdev whose egress hooks shall be applied to @skb
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*
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* Returns @skb on success or %NULL if the packet was consumed or filtered.
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* Caller must hold rcu_read_lock.
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*
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* On ingress, packets are classified first by tc, then by netfilter.
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* On egress, the order is reversed for symmetry. Conceptually, tc and
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* netfilter can be thought of as layers, with netfilter layered above tc:
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* When tc redirects a packet to another interface, netfilter is not applied
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* because the packet is on the tc layer.
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*
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* The nf_skip_egress flag controls whether netfilter is applied on egress.
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* It is updated by __netif_receive_skb_core() and __dev_queue_xmit() when the
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* packet passes through tc and netfilter. Because __dev_queue_xmit() may be
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* called recursively by tunnel drivers such as vxlan, the flag is reverted to
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* false after sch_handle_egress(). This ensures that netfilter is applied
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* both on the overlay and underlying network.
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*/
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static inline struct sk_buff *nf_hook_egress(struct sk_buff *skb, int *rc,
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struct net_device *dev)
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{
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struct nf_hook_entries *e;
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struct nf_hook_state state;
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int ret;
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#ifdef CONFIG_NETFILTER_SKIP_EGRESS
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if (skb->nf_skip_egress)
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return skb;
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#endif
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e = rcu_dereference_check(dev->nf_hooks_egress, rcu_read_lock_bh_held());
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if (!e)
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return skb;
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nf_hook_state_init(&state, NF_NETDEV_EGRESS,
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NFPROTO_NETDEV, NULL, dev, NULL,
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dev_net(dev), NULL);
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/* nf assumes rcu_read_lock, not just read_lock_bh */
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rcu_read_lock();
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ret = nf_hook_slow(skb, &state, e, 0);
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rcu_read_unlock();
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if (ret == 1) {
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return skb;
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} else if (ret < 0) {
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*rc = NET_XMIT_DROP;
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return NULL;
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} else { /* ret == 0 */
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*rc = NET_XMIT_SUCCESS;
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return NULL;
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}
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}
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#else /* CONFIG_NETFILTER_EGRESS */
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static inline bool nf_hook_egress_active(void)
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{
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return false;
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}
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static inline struct sk_buff *nf_hook_egress(struct sk_buff *skb, int *rc,
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struct net_device *dev)
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{
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return skb;
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}
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#endif /* CONFIG_NETFILTER_EGRESS */
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static inline void nf_skip_egress(struct sk_buff *skb, bool skip)
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{
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#ifdef CONFIG_NETFILTER_SKIP_EGRESS
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skb->nf_skip_egress = skip;
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#endif
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}
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static inline void nf_hook_netdev_init(struct net_device *dev)
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{
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#ifdef CONFIG_NETFILTER_INGRESS
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RCU_INIT_POINTER(dev->nf_hooks_ingress, NULL);
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#endif
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#ifdef CONFIG_NETFILTER_EGRESS
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RCU_INIT_POINTER(dev->nf_hooks_egress, NULL);
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#endif
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}
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#endif /* _NETFILTER_NETDEV_H_ */
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