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a171fbec88
LWTUNNEL_XMIT_CONTINUE is implicitly assumed in ip(6)_finish_output2,
such that any positive return value from a xmit hook could cause
unexpected continue behavior, despite that related skb may have been
freed. This could be error-prone for future xmit hook ops. One of the
possible errors is to return statuses of dst_output directly.
To make the code safer, redefine LWTUNNEL_XMIT_CONTINUE value to
distinguish from dst_output statuses and check the continue
condition explicitly.
Fixes: 3a0af8fd61 ("bpf: BPF for lightweight tunnel infrastructure")
Suggested-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Yan Zhai <yan@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/96b939b85eda00e8df4f7c080f770970a4c5f698.1692326837.git.yan@cloudflare.com
270 lines
6.6 KiB
C
270 lines
6.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __NET_LWTUNNEL_H
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#define __NET_LWTUNNEL_H 1
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#include <linux/lwtunnel.h>
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#include <linux/netdevice.h>
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#include <linux/skbuff.h>
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#include <linux/types.h>
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#include <net/route.h>
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#define LWTUNNEL_HASH_BITS 7
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#define LWTUNNEL_HASH_SIZE (1 << LWTUNNEL_HASH_BITS)
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/* lw tunnel state flags */
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#define LWTUNNEL_STATE_OUTPUT_REDIRECT BIT(0)
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#define LWTUNNEL_STATE_INPUT_REDIRECT BIT(1)
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#define LWTUNNEL_STATE_XMIT_REDIRECT BIT(2)
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/* LWTUNNEL_XMIT_CONTINUE should be distinguishable from dst_output return
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* values (NET_XMIT_xxx and NETDEV_TX_xxx in linux/netdevice.h) for safety.
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*/
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enum {
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LWTUNNEL_XMIT_DONE,
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LWTUNNEL_XMIT_CONTINUE = 0x100,
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};
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struct lwtunnel_state {
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__u16 type;
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__u16 flags;
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__u16 headroom;
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atomic_t refcnt;
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int (*orig_output)(struct net *net, struct sock *sk, struct sk_buff *skb);
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int (*orig_input)(struct sk_buff *);
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struct rcu_head rcu;
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__u8 data[];
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};
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struct lwtunnel_encap_ops {
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int (*build_state)(struct net *net, struct nlattr *encap,
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unsigned int family, const void *cfg,
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struct lwtunnel_state **ts,
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struct netlink_ext_ack *extack);
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void (*destroy_state)(struct lwtunnel_state *lws);
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int (*output)(struct net *net, struct sock *sk, struct sk_buff *skb);
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int (*input)(struct sk_buff *skb);
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int (*fill_encap)(struct sk_buff *skb,
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struct lwtunnel_state *lwtstate);
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int (*get_encap_size)(struct lwtunnel_state *lwtstate);
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int (*cmp_encap)(struct lwtunnel_state *a, struct lwtunnel_state *b);
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int (*xmit)(struct sk_buff *skb);
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struct module *owner;
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};
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#ifdef CONFIG_LWTUNNEL
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DECLARE_STATIC_KEY_FALSE(nf_hooks_lwtunnel_enabled);
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void lwtstate_free(struct lwtunnel_state *lws);
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static inline struct lwtunnel_state *
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lwtstate_get(struct lwtunnel_state *lws)
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{
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if (lws)
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atomic_inc(&lws->refcnt);
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return lws;
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}
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static inline void lwtstate_put(struct lwtunnel_state *lws)
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{
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if (!lws)
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return;
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if (atomic_dec_and_test(&lws->refcnt))
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lwtstate_free(lws);
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}
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static inline bool lwtunnel_output_redirect(struct lwtunnel_state *lwtstate)
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{
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if (lwtstate && (lwtstate->flags & LWTUNNEL_STATE_OUTPUT_REDIRECT))
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return true;
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return false;
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}
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static inline bool lwtunnel_input_redirect(struct lwtunnel_state *lwtstate)
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{
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if (lwtstate && (lwtstate->flags & LWTUNNEL_STATE_INPUT_REDIRECT))
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return true;
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return false;
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}
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static inline bool lwtunnel_xmit_redirect(struct lwtunnel_state *lwtstate)
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{
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if (lwtstate && (lwtstate->flags & LWTUNNEL_STATE_XMIT_REDIRECT))
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return true;
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return false;
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}
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static inline unsigned int lwtunnel_headroom(struct lwtunnel_state *lwtstate,
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unsigned int mtu)
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{
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if ((lwtunnel_xmit_redirect(lwtstate) ||
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lwtunnel_output_redirect(lwtstate)) && lwtstate->headroom < mtu)
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return lwtstate->headroom;
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return 0;
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}
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int lwtunnel_encap_add_ops(const struct lwtunnel_encap_ops *op,
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unsigned int num);
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int lwtunnel_encap_del_ops(const struct lwtunnel_encap_ops *op,
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unsigned int num);
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int lwtunnel_valid_encap_type(u16 encap_type,
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struct netlink_ext_ack *extack);
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int lwtunnel_valid_encap_type_attr(struct nlattr *attr, int len,
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struct netlink_ext_ack *extack);
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int lwtunnel_build_state(struct net *net, u16 encap_type,
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struct nlattr *encap,
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unsigned int family, const void *cfg,
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struct lwtunnel_state **lws,
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struct netlink_ext_ack *extack);
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int lwtunnel_fill_encap(struct sk_buff *skb, struct lwtunnel_state *lwtstate,
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int encap_attr, int encap_type_attr);
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int lwtunnel_get_encap_size(struct lwtunnel_state *lwtstate);
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struct lwtunnel_state *lwtunnel_state_alloc(int hdr_len);
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int lwtunnel_cmp_encap(struct lwtunnel_state *a, struct lwtunnel_state *b);
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int lwtunnel_output(struct net *net, struct sock *sk, struct sk_buff *skb);
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int lwtunnel_input(struct sk_buff *skb);
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int lwtunnel_xmit(struct sk_buff *skb);
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int bpf_lwt_push_ip_encap(struct sk_buff *skb, void *hdr, u32 len,
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bool ingress);
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static inline void lwtunnel_set_redirect(struct dst_entry *dst)
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{
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if (lwtunnel_output_redirect(dst->lwtstate)) {
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dst->lwtstate->orig_output = dst->output;
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dst->output = lwtunnel_output;
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}
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if (lwtunnel_input_redirect(dst->lwtstate)) {
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dst->lwtstate->orig_input = dst->input;
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dst->input = lwtunnel_input;
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}
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}
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#else
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static inline void lwtstate_free(struct lwtunnel_state *lws)
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{
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}
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static inline struct lwtunnel_state *
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lwtstate_get(struct lwtunnel_state *lws)
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{
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return lws;
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}
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static inline void lwtstate_put(struct lwtunnel_state *lws)
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{
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}
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static inline bool lwtunnel_output_redirect(struct lwtunnel_state *lwtstate)
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{
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return false;
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}
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static inline bool lwtunnel_input_redirect(struct lwtunnel_state *lwtstate)
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{
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return false;
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}
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static inline bool lwtunnel_xmit_redirect(struct lwtunnel_state *lwtstate)
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{
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return false;
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}
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static inline void lwtunnel_set_redirect(struct dst_entry *dst)
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{
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}
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static inline unsigned int lwtunnel_headroom(struct lwtunnel_state *lwtstate,
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unsigned int mtu)
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{
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return 0;
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}
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static inline int lwtunnel_encap_add_ops(const struct lwtunnel_encap_ops *op,
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unsigned int num)
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{
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return -EOPNOTSUPP;
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}
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static inline int lwtunnel_encap_del_ops(const struct lwtunnel_encap_ops *op,
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unsigned int num)
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{
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return -EOPNOTSUPP;
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}
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static inline int lwtunnel_valid_encap_type(u16 encap_type,
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struct netlink_ext_ack *extack)
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{
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NL_SET_ERR_MSG(extack, "CONFIG_LWTUNNEL is not enabled in this kernel");
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return -EOPNOTSUPP;
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}
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static inline int lwtunnel_valid_encap_type_attr(struct nlattr *attr, int len,
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struct netlink_ext_ack *extack)
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{
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/* return 0 since we are not walking attr looking for
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* RTA_ENCAP_TYPE attribute on nexthops.
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*/
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return 0;
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}
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static inline int lwtunnel_build_state(struct net *net, u16 encap_type,
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struct nlattr *encap,
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unsigned int family, const void *cfg,
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struct lwtunnel_state **lws,
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struct netlink_ext_ack *extack)
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{
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return -EOPNOTSUPP;
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}
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static inline int lwtunnel_fill_encap(struct sk_buff *skb,
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struct lwtunnel_state *lwtstate,
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int encap_attr, int encap_type_attr)
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{
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return 0;
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}
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static inline int lwtunnel_get_encap_size(struct lwtunnel_state *lwtstate)
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{
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return 0;
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}
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static inline struct lwtunnel_state *lwtunnel_state_alloc(int hdr_len)
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{
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return NULL;
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}
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static inline int lwtunnel_cmp_encap(struct lwtunnel_state *a,
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struct lwtunnel_state *b)
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{
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return 0;
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}
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static inline int lwtunnel_output(struct net *net, struct sock *sk, struct sk_buff *skb)
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{
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return -EOPNOTSUPP;
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}
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static inline int lwtunnel_input(struct sk_buff *skb)
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{
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return -EOPNOTSUPP;
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}
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static inline int lwtunnel_xmit(struct sk_buff *skb)
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{
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return -EOPNOTSUPP;
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}
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#endif /* CONFIG_LWTUNNEL */
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#define MODULE_ALIAS_RTNL_LWT(encap_type) MODULE_ALIAS("rtnl-lwt-" __stringify(encap_type))
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#endif /* __NET_LWTUNNEL_H */
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