path: root/include/linux/netfilter/x_tables.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _X_TABLES_H
#define _X_TABLES_H


#include <linux/netdevice.h>
#include <linux/static_key.h>
#include <linux/netfilter.h>
#include <uapi/linux/netfilter/x_tables.h>

/* Test a struct->invflags and a boolean for inequality */
#define NF_INVF(ptr, flag, boolean)					\
	((boolean) ^ !!((ptr)->invflags & (flag)))

/**
 * struct xt_action_param - parameters for matches/targets
 *
 * @match:	the match extension
 * @target:	the target extension
 * @matchinfo:	per-match data
 * @targetinfo:	per-target data
 * @state:	pointer to hook state this packet came from
 * @fragoff:	packet is a fragment, this is the data offset
 * @thoff:	position of transport header relative to skb->data
 *
 * Fields written to by extensions:
 *
 * @hotdrop:	drop packet if we had inspection problems
 */
struct xt_action_param {
	union {
		const struct xt_match *match;
		const struct xt_target *target;
	};
	union {
		const void *matchinfo, *targinfo;
	};
	const struct nf_hook_state *state;
	int fragoff;
	unsigned int thoff;
	bool hotdrop;
};

static inline struct net *xt_net(const struct xt_action_param *par)
{
	return par->state->net;
}

static inline struct net_device *xt_in(const struct xt_action_param *par)
{
	return par->state->in;
}

static inline const char *xt_inname(const struct xt_action_param *par)
{
	return par->state->in->name;
}

static inline struct net_device *xt_out(const struct xt_action_param *par)
{
	return par->state->out;
}

static inline const char *xt_outname(const struct xt_action_param *par)
{
	return par->state->out->name;
}

static inline unsigned int xt_hooknum(const struct xt_action_param *par)
{
	return par->state->hook;
}

static inline u_int8_t xt_family(const struct xt_action_param *par)
{
	return par->state->pf;
}

/**
 * struct xt_mtchk_param - parameters for match extensions'
 * checkentry functions
 *
 * @net:	network namespace through which the check was invoked
 * @table:	table the rule is tried to be inserted into
 * @entryinfo:	the family-specific rule data
 * 		(struct ipt_ip, ip6t_ip, arpt_arp or (note) ebt_entry)
 * @match:	struct xt_match through which this function was invoked
 * @matchinfo:	per-match data
 * @hook_mask:	via which hooks the new rule is reachable
 * Other fields as above.
 */
struct xt_mtchk_param {
	struct net *net;
	const char *table;
	const void *entryinfo;
	const struct xt_match *match;
	void *matchinfo;
	unsigned int hook_mask;
	u_int8_t family;
	bool nft_compat;
};

/**
 * struct xt_mdtor_param - match destructor parameters
 * Fields as above.
 */
struct xt_mtdtor_param {
	struct net *net;
	const struct xt_match *match;
	void *matchinfo;
	u_int8_t family;
};

/**
 * struct xt_tgchk_param - parameters for target extensions'
 * checkentry functions
 *
 * @entryinfo:	the family-specific rule data
 * 		(struct ipt_entry, ip6t_entry, arpt_entry, ebt_entry)
 *
 * Other fields see above.
 */
struct xt_tgchk_param {
	struct net *net;
	const char *table;
	const void *entryinfo;
	const struct xt_target *target;
	void *targinfo;
	unsigned int hook_mask;
	u_int8_t family;
	bool nft_compat;
};

/* Target destructor parameters */
struct xt_tgdtor_param {
	struct net *net;
	const struct xt_target *target;
	void *targinfo;
	u_int8_t family;
};

struct xt_match {
	struct list_head list;

	const char name[XT_EXTENSION_MAXNAMELEN];
	u_int8_t revision;

	/* Return true or false: return FALSE and set *hotdrop = 1 to
           force immediate packet drop. */
	/* Arguments changed since 2.6.9, as this must now handle
	   non-linear skb, using skb_header_pointer and
	   skb_ip_make_writable. */
	bool (*match)(const struct sk_buff *skb,
		      struct xt_action_param *);

	/* Called when user tries to insert an entry of this type. */
	int (*checkentry)(const struct xt_mtchk_param *);

	/* Called when entry of this type deleted. */
	void (*destroy)(const struct xt_mtdtor_param *);
#ifdef CONFIG_COMPAT
	/* Called when userspace align differs from kernel space one */
	void (*compat_from_user)(void *dst, const void *src);
	int (*compat_to_user)(void __user *dst, const void *src);
#endif
	/* Set this to THIS_MODULE if you are a module, otherwise NULL */
	struct module *me;

	const char *table;
	unsigned int matchsize;
	unsigned int usersize;
#ifdef CONFIG_COMPAT
	unsigned int compatsize;
#endif
	unsigned int hooks;
	unsigned short proto;

	unsigned short family;
};

/* Registration hooks for targets. */
struct xt_target {
	struct list_head list;

	const char name[XT_EXTENSION_MAXNAMELEN];
	u_int8_t revision;

	/* Returns verdict. Argument order changed since 2.6.9, as this
	   must now handle non-linear skbs, using skb_copy_bits and
	   skb_ip_make_writable. */
	unsigned int (*target)(struct sk_buff *skb,
			       const struct xt_action_param *);

	/* Called when user tries to insert an entry of this type:
           hook_mask is a bitmask of hooks from which it can be
           called. */
	/* Should return 0 on success or an error code otherwise (-Exxxx). */
	int (*checkentry)(const struct xt_tgchk_param *);

	/* Called when entry of this type deleted. */
	void (*destroy)(const struct xt_tgdtor_param *);
#ifdef CONFIG_COMPAT
	/* Called when userspace align differs from kernel space one */
	void (*compat_from_user)(void *dst, const void *src);
	int (*compat_to_user)(void __user *dst, const void *src);
#endif
	/* Set this to THIS_MODULE if you are a module, otherwise NULL */
	struct module *me;

	const char *table;
	unsigned int targetsize;
	unsigned int usersize;
#ifdef CONFIG_COMPAT
	unsigned int compatsize;
#endif
	unsigned int hooks;
	unsigned short proto;

	unsigned short family;
};

/* Furniture shopping... */
struct xt_table {
	struct list_head list;

	/* What hooks you will enter on */
	unsigned int valid_hooks;

	/* Man behind the curtain... */
	struct xt_table_info *private;

	/* Set this to THIS_MODULE if you are a module, otherwise NULL */
	struct module *me;

	u_int8_t af;		/* address/protocol family */
	int priority;		/* hook order */

	/* called when table is needed in the given netns */
	int (*table_init)(struct net *net);

	/* A unique name... */
	const char name[XT_TABLE_MAXNAMELEN];
};

#include <linux/netfilter_ipv4.h>

/* The table itself */
struct xt_table_info {
	/* Size per table */
	unsigned int size;
	/* Number of entries: FIXME. --RR */
	unsigned int number;
	/* Initial number of entries. Needed for module usage count */
	unsigned int initial_entries;

	/* Entry points and underflows */
	unsigned int hook_entry[NF_INET_NUMHOOKS];
	unsigned int underflow[NF_INET_NUMHOOKS];

	/*
	 * Number of user chains. Since tables cannot have loops, at most
	 * @stacksize jumps (number of user chains) can possibly be made.
	 */
	unsigned int stacksize;
	void ***jumpstack;

	unsigned char entries[] __aligned(8);
};

int xt_register_target(struct xt_target *target);
void xt_unregister_target(struct xt_target *target);
int xt_register_targets(struct xt_target *target, unsigned int n);
void xt_unregister_targets(struct xt_target *target, unsigned int n);

int xt_register_match(struct xt_match *target);
void xt_unregister_match(struct xt_match *target);
int xt_register_matches(struct xt_match *match, unsigned int n);
void xt_unregister_matches(struct xt_match *match, unsigned int n);

int xt_check_entry_offsets(const void *base, const char *elems,
			   unsigned int target_offset,
			   unsigned int next_offset);

int xt_check_table_hooks(const struct xt_table_info *info, unsigned int valid_hooks);

unsigned int *xt_alloc_entry_offsets(unsigned int size);
bool xt_find_jump_offset(const unsigned int *offsets,
			 unsigned int target, unsigned int size);

i