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kernel/include/linux/netfilter.h
Phil Sutter 73319a8ee1 netfilter: nf_tables: Have a list of nf_hook_ops in nft_hook 
Supporting a 1:n relationship between nft_hook and nf_hook_ops is
convenient since a chain's or flowtable's nft_hooks may remain in place
despite matching interfaces disappearing. This stabilizes ruleset dumps
in that regard and opens the possibility to claim newly added interfaces
which match the spec. Also it prepares for wildcard interface specs
since these will potentially match multiple interfaces.

All spots dealing with hook registration are updated to handle a list of
multiple nf_hook_ops, but nft_netdev_hook_alloc() only adds a single
item for now to retain the old behaviour. The only expected functional
change here is how vanishing interfaces are handled: Instead of dropping
the respective nft_hook, only the matching nf_hook_ops are dropped.

To safely remove individual ops from the list in netdev handlers, an
rcu_head is added to struct nf_hook_ops so kfree_rcu() may be used.
There is at least nft_flowtable_find_dev() which may be iterating
through the list at the same time.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2025-05-23 13:57:13 +02:00

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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_NETFILTER_H
#define __LINUX_NETFILTER_H
#include <linux/init.h>
#include <linux/skbuff.h>
#include <linux/net.h>
#include <linux/if.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/wait.h>
#include <linux/list.h>
#include <linux/static_key.h>
#include <linux/module.h>
#include <linux/netfilter_defs.h>
#include <linux/netdevice.h>
#include <linux/sockptr.h>
#include <net/net_namespace.h>
static inline int NF_DROP_GETERR(int verdict)
{
return -(verdict >> NF_VERDICT_QBITS);
}
static __always_inline int
NF_DROP_REASON(struct sk_buff *skb, enum skb_drop_reason reason, u32 err)
{
BUILD_BUG_ON(err > 0xffff);
kfree_skb_reason(skb, reason);
return ((err << 16) | NF_STOLEN);
}
static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
const union nf_inet_addr *a2)
{
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
const unsigned long *ul1 = (const unsigned long *)a1;
const unsigned long *ul2 = (const unsigned long *)a2;
return ((ul1[0] ^ ul2[0]) | (ul1[1] ^ ul2[1])) == 0UL;
#else
return a1->all[0] == a2->all[0] &&
a1->all[1] == a2->all[1] &&
a1->all[2] == a2->all[2] &&
a1->all[3] == a2->all[3];
#endif
}
static inline void nf_inet_addr_mask(const union nf_inet_addr *a1,
union nf_inet_addr *result,
const union nf_inet_addr *mask)
{
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
const unsigned long *ua = (const unsigned long *)a1;
unsigned long *ur = (unsigned long *)result;
const unsigned long *um = (const unsigned long *)mask;
ur[0] = ua[0] & um[0];
ur[1] = ua[1] & um[1];
#else
result->all[0] = a1->all[0] & mask->all[0];
result->all[1] = a1->all[1] & mask->all[1];
result->all[2] = a1->all[2] & mask->all[2];
result->all[3] = a1->all[3] & mask->all[3];
#endif
}
int netfilter_init(void);
struct sk_buff;
struct nf_hook_ops;
struct sock;
struct nf_hook_state {
u8 hook;
u8 pf;
struct net_device *in;
struct net_device *out;
struct sock *sk;
struct net *net;
int (*okfn)(struct net *, struct sock *, struct sk_buff *);
};
typedef unsigned int nf_hookfn(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state);
enum nf_hook_ops_type {
NF_HOOK_OP_UNDEFINED,
NF_HOOK_OP_NF_TABLES,
NF_HOOK_OP_BPF,
};
struct nf_hook_ops {
struct list_head list;
struct rcu_head rcu;
/* User fills in from here down. */
nf_hookfn *hook;
struct net_device *dev;
void *priv;
u8 pf;
enum nf_hook_ops_type hook_ops_type:8;
unsigned int hooknum;
/* Hooks are ordered in ascending priority. */
int priority;
};
struct nf_hook_entry {
nf_hookfn *hook;
void *priv;
};
struct nf_hook_entries_rcu_head {
struct rcu_head head;
void *allocation;
};
struct nf_hook_entries {
u16 num_hook_entries;
/* padding */
struct nf_hook_entry hooks[];
/* trailer: pointers to original orig_ops of each hook,
* followed by rcu_head and scratch space used for freeing
* the structure via call_rcu.
*
* This is not part of struct nf_hook_entry since its only
* needed in slow path (hook register/unregister):
* const struct nf_hook_ops *orig_ops[]
*
* For the same reason, we store this at end -- its
* only needed when a hook is deleted, not during
* packet path processing:
* struct nf_hook_entries_rcu_head head
*/
};
#ifdef CONFIG_NETFILTER
static inline struct nf_hook_ops **nf_hook_entries_get_hook_ops(const struct nf_hook_entries *e)
{
unsigned int n = e->num_hook_entries;
const void *hook_end;
hook_end = &e->hooks[n]; /* this is *past* ->hooks[]! */
return (struct nf_hook_ops **)hook_end;
}
static inline int
nf_hook_entry_hookfn(const struct nf_hook_entry *entry, struct sk_buff *skb,
struct nf_hook_state *state)
{
return entry->hook(entry->priv, skb, state);
}
static inline void nf_hook_state_init(struct nf_hook_state *p,
unsigned int hook,
u_int8_t pf,
struct net_device *indev,
struct net_device *outdev,
struct sock *sk,
struct net *net,
int (*okfn)(struct net *, struct sock *, struct sk_buff *))
{
p->hook = hook;
p->pf = pf;
p->in = indev;
p->out = outdev;
p->sk = sk;
p->net = net;
p->okfn = okfn;
}
struct nf_sockopt_ops {
struct list_head list;
u_int8_t pf;
/* Non-inclusive ranges: use 0/0/NULL to never get called. */
int set_optmin;
int set_optmax;
int (*set)(struct sock *sk, int optval, sockptr_t arg,
unsigned int len);
int get_optmin;
int get_optmax;
int (*get)(struct sock *sk, int optval, void __user *user, int *len);
/* Use the module struct to lock set/get code in place */
struct module *owner;
};
/* Function to register/unregister hook points. */
int nf_register_net_hook(struct net *net, const struct nf_hook_ops *ops);
void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *ops);
int nf_register_net_hooks(struct net *net, const struct nf_hook_ops *reg,
unsigned int n);
void nf_unregister_net_hooks(struct net *net, const struct nf_hook_ops *reg,
unsigned int n);
/* Functions to register get/setsockopt ranges (non-inclusive). You
need to check permissions yourself! */
int nf_register_sockopt(struct nf_sockopt_ops *reg);
void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
#ifdef CONFIG_JUMP_LABEL
extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
#endif
int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state,
const struct nf_hook_entries *e, unsigned int i);
void nf_hook_slow_list(struct list_head *head, struct nf_hook_state *state,
const struct nf_hook_entries *e);
/**
* nf_hook - call a netfilter hook
*
* Returns 1 if the hook has allowed the packet to pass. The function
* okfn must be invoked by the caller in this case. Any other return
* value indicates the packet has been consumed by the hook.
*/
static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,
struct sock *sk, struct sk_buff *skb,
struct net_device *indev, struct net_device *outdev,
int (*okfn)(struct net *, struct sock *, struct sk_buff *))
{
struct nf_hook_entries *hook_head = NULL;
int ret = 1;
#ifdef CONFIG_JUMP_LABEL
if (__builtin_constant_p(pf) &&
__builtin_constant_p(hook) &&
!static_key_false(&nf_hooks_needed[pf][hook]))
return 1;
#endif
rcu_read_lock();
switch (pf) {
case NFPROTO_IPV4:
hook_head = rcu_dereference(net->nf.hooks_ipv4[hook]);
break;
case NFPROTO_IPV6:
hook_head = rcu_dereference(net->nf.hooks_ipv6[hook]);
break;
case NFPROTO_ARP:
#ifdef CONFIG_NETFILTER_FAMILY_ARP
if (WARN_ON_ONCE(hook >= ARRAY_SIZE(net->nf.hooks_arp)))
break;
hook_head = rcu_dereference(net->nf.hooks_arp[hook]);
#endif
break;
case NFPROTO_BRIDGE:
#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
hook_head = rcu_dereference(net->nf.hooks_bridge[hook]);
#endif
break;
default:
WARN_ON_ONCE(1);
break;
}
if (hook_head) {
struct nf_hook_state state;
nf_hook_state_init(&state, hook, pf, indev, outdev,
sk, net, okfn);
ret = nf_hook_slow(skb, &state, hook_head, 0);
}
rcu_read_unlock();
return ret;
}
/* Activate hook; either okfn or kfree_skb called, unless a hook
returns NF_STOLEN (in which case, it's up to the hook to deal with
the consequences).
Returns -ERRNO if packet dropped. Zero means queued, stolen or
accepted.
*/
/* RR:
> I don't want nf_hook to return anything because people might forget
> about async and trust the return value to mean "packet was ok".
AK:
Just document it clearly, then you can expect some sense from kernel
coders :)
*/
static inline int
NF_HOOK_COND(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
struct sk_buff *skb, struct net_device *in, struct net_device *out,
int (*okfn)(struct net *, struct sock *, struct sk_buff *),
bool cond)
{
int ret;
if (!cond ||
((ret = nf_hook(pf, hook, net, sk, skb, in, out, okfn)) == 1))
ret = okfn(net, sk, skb);
return ret;
}
static inline int
NF_HOOK(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk, struct sk_buff *skb,
struct net_device *in, struct net_device *out,
int (*okfn)(struct net *, struct sock *, struct sk_buff *))
{
int ret = nf_hook(pf, hook, net, sk, skb, in, out, okfn);
if (ret == 1)
ret = okfn(net, sk, skb);
return ret;
}
static inline void
NF_HOOK_LIST(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
struct list_head *head, struct net_device *in, struct net_device *out,
int (*okfn)(struct net *, struct sock *, struct sk_buff *))
{
struct nf_hook_entries *hook_head = NULL;
#ifdef CONFIG_JUMP_LABEL
if (__builtin_constant_p(pf) &&
__builtin_constant_p(hook) &&
!static_key_false(&nf_hooks_needed[pf][hook]))
return;
#endif
rcu_read_lock();
switch (pf) {
case NFPROTO_IPV4:
hook_head = rcu_dereference(net->nf.hooks_ipv4[hook]);
break;
case NFPROTO_IPV6:
hook_head = rcu_dereference(net->nf.hooks_ipv6[hook]);
break;
default:
WARN_ON_ONCE(1);
break;
}
if (hook_head) {
struct nf_hook_state state;
nf_hook_state_init(&state, hook, pf, in, out, sk, net, okfn);
nf_hook_slow_list(head, &state, hook_head);
}
rcu_read_unlock();
}
/* Call setsockopt() */
int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, sockptr_t opt,
unsigned int len);
int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
int *len);
struct flowi;
struct nf_queue_entry;
__sum16 nf_checksum(struct sk_buff *skb, unsigned int hook,
unsigned int dataoff, u_int8_t protocol,
unsigned short family);
__sum16 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
unsigned int dataoff, unsigned int len,
u_int8_t protocol, unsigned short family);
int nf_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
bool strict, unsigned short family);
#include <net/flow.h>
struct nf_conn;
enum nf_nat_manip_type;
struct nlattr;
struct nf_nat_hook {
int (*parse_nat_setup)(struct nf_conn *ct, enum nf_nat_manip_type manip,
const struct nlattr *attr);
void (*decode_session)(struct sk_buff *skb, struct flowi *fl);
void (*remove_nat_bysrc)(struct nf_conn *ct);
};
extern const struct nf_nat_hook __rcu *nf_nat_hook;
static inline void
nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
{
#if IS_ENABLED(CONFIG_NF_NAT)
const struct nf_nat_hook *nat_hook;
rcu_read_lock();
nat_hook = rcu_dereference(nf_nat_hook);
if (nat_hook && nat_hook->decode_session)
nat_hook->decode_session(skb, fl);
rcu_read_unlock();
#endif
}
#else /* !CONFIG_NETFILTER */
static inline int
NF_HOOK_COND(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
struct sk_buff *skb, struct net_device *in, struct net_device *out,
int (*okfn)(struct net *, struct sock *, struct sk_buff *),
bool cond)
{
return okfn(net, sk, skb);
}
static inline int
NF_HOOK(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
struct sk_buff *skb, struct net_device *in, struct net_device *out,
int (*okfn)(struct net *, struct sock *, struct sk_buff *))
{
return okfn(net, sk, skb);
}
static inline void
NF_HOOK_LIST(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
struct list_head *head, struct net_device *in, struct net_device *out,
int (*okfn)(struct net *, struct sock *, struct sk_buff *))
{
/* nothing to do */
}
static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,
struct sock *sk, struct sk_buff *skb,
struct net_device *indev, struct net_device *outdev,
int (*okfn)(struct net *, struct sock *, struct sk_buff *))
{
return 1;
}
struct flowi;
static inline void
nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
{
}
#endif /*CONFIG_NETFILTER*/
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
#include <linux/netfilter/nf_conntrack_zones_common.h>
void nf_ct_attach(struct sk_buff *, const struct sk_buff *);
void nf_ct_set_closing(struct nf_conntrack *nfct);
struct nf_conntrack_tuple;
bool nf_ct_get_tuple_skb(struct nf_conntrack_tuple *dst_tuple,
const struct sk_buff *skb);
#else
static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
static inline void nf_ct_set_closing(struct nf_conntrack *nfct) {}
struct nf_conntrack_tuple;
static inline bool nf_ct_get_tuple_skb(struct nf_conntrack_tuple *dst_tuple,
const struct sk_buff *skb)
{
return false;
}
#endif
struct nf_conn;
enum ip_conntrack_info;
struct nf_ct_hook {
int (*update)(struct net *net, struct sk_buff *skb);
void (*destroy)(struct nf_conntrack *);
bool (*get_tuple_skb)(struct nf_conntrack_tuple *,
const struct sk_buff *);
void (*attach)(struct sk_buff *nskb, const struct sk_buff *skb);
void (*set_closing)(struct nf_conntrack *nfct);
int (*confirm)(struct sk_buff *skb);
u32 (*get_id)(const struct nf_conntrack *nfct);
};
extern const struct nf_ct_hook __rcu *nf_ct_hook;
struct nlattr;
struct nfnl_ct_hook {
size_t (*build_size)(const struct nf_conn *ct);
int (*build)(struct sk_buff *skb, struct nf_conn *ct,
enum ip_conntrack_info ctinfo,
u_int16_t ct_attr, u_int16_t ct_info_attr);
int (*parse)(const struct nlattr *attr, struct nf_conn *ct);
int (*attach_expect)(const struct nlattr *attr, struct nf_conn *ct,
u32 portid, u32 report);
void (*seq_adjust)(struct sk_buff *skb, struct nf_conn *ct,
enum ip_conntrack_info ctinfo, s32 off);
};
extern const struct nfnl_ct_hook __rcu *nfnl_ct_hook;
struct nf_defrag_hook {
struct module *owner;
int (*enable)(struct net *net);
void (*disable)(struct net *net);
};
extern const struct nf_defrag_hook __rcu *nf_defrag_v4_hook;
extern const struct nf_defrag_hook __rcu *nf_defrag_v6_hook;
/*
* Contains bitmask of ctnetlink event subscribers, if any.
* Can't be pernet due to NETLINK_LISTEN_ALL_NSID setsockopt flag.
*/
extern u8 nf_ctnetlink_has_listener;
#endif /*__LINUX_NETFILTER_H*/
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