Release 4.7 include/linux/netfilter/x_tables.h

#ifndef _X_TABLES_H

#define _X_TABLES_H


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

/**
 * struct xt_action_param - parameters for matches/targets
 *
 * @match:      the match extension
 * @target:     the target extension
 * @matchinfo:  per-match data
 * @targetinfo: per-target data
 * @net         network namespace through which the action was invoked
 * @in:         input netdevice
 * @out:        output netdevice
 * @fragoff:    packet is a fragment, this is the data offset
 * @thoff:      position of transport header relative to skb->data
 * @hook:       hook number given packet came from
 * @family:     Actual NFPROTO_* through which the function is invoked
 *              (helpful when match->family == NFPROTO_UNSPEC)
 *
 * 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;
	};
	
struct net *net;
	

const struct net_device *in, *out;
	
int fragoff;
	
unsigned int thoff;
	
unsigned int hooknum;
	
u_int8_t family;
	
bool hotdrop;
};

/**
 * 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;
#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;
#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[0] __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_match(struct xt_mtchk_param *, unsigned int size, u_int8_t proto,
		   bool inv_proto);
int xt_check_target(struct xt_tgchk_param *, unsigned int size, u_int8_t proto,
		    bool inv_proto);

void *xt_copy_counters_from_user(const void __user *user, unsigned int len,
				 struct xt_counters_info *info, bool compat);

struct xt_table *xt_register_table(struct net *net,
				   const struct xt_table *table,
				   struct xt_table_info *bootstrap,
				   struct xt_table_info *newinfo);
void *xt_unregister_table(struct xt_table *table);

struct xt_table_info *xt_replace_table(struct xt_table *table,
				       unsigned int num_counters,
				       struct xt_table_info *newinfo,
				       int *error);

struct xt_match *xt_find_match(u8 af, const char *name, u8 revision);
struct xt_target *xt_find_target(u8 af, const char *name, u8 revision);
struct xt_match *xt_request_find_match(u8 af, const char *name, u8 revision);
struct xt_target *xt_request_find_target(u8 af, const char *name, u8 revision);
int xt_find_revision(u8 af, const char *name, u8 revision, int target,
		     int *err);

struct xt_table *xt_find_table_lock(struct net *net, u_int8_t af,
				    const char *name);
void xt_table_unlock(struct xt_table *t);

int xt_proto_init(struct net *net, u_int8_t af);
void xt_proto_fini(struct net *net, u_int8_t af);

struct xt_table_info *xt_alloc_table_info(unsigned int size);
void xt_free_table_info(struct xt_table_info *info);

/**
 * xt_recseq - recursive seqcount for netfilter use
 * 
 * Packet processing changes the seqcount only if no recursion happened
 * get_counters() can use read_seqcount_begin()/read_seqcount_retry(),
 * because we use the normal seqcount convention :
 * Low order bit set to 1 if a writer is active.
 */
DECLARE_PER_CPU(seqcount_t, xt_recseq);

/* xt_tee_enabled - true if x_tables needs to handle reentrancy
 *
 * Enabled if current ip(6)tables ruleset has at least one -j TEE rule.
 */
extern struct static_key xt_tee_enabled;

/**
 * xt_write_recseq_begin - start of a write section
 *
 * Begin packet processing : all readers must wait the end
 * 1) Must be called with preemption disabled
 * 2) softirqs must be disabled too (or we should use this_cpu_add())
 * Returns :
 *  1 if no recursion on this cpu
 *  0 if recursion detected
 */


static inline unsigned int xt_write_recseq_begin(void)
{
	unsigned int addend;

	/*
         * Low order bit of sequence is set if we already
         * called xt_write_recseq_begin().
         */
	addend = (__this_cpu_read(xt_recseq.sequence) + 1) & 1;

	/*
         * This is kind of a write_seqcount_begin(), but addend is 0 or 1
         * We dont check addend value to avoid a test and conditional jump,
         * since addend is most likely 1
         */
	__this_cpu_add(xt_recseq.sequence, addend);
	smp_wmb();

	return addend;
}

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/**
 * xt_write_recseq_end - end of a write section
 * @addend: return value from previous xt_write_recseq_begin()
 *
 * End packet processing : all readers can proceed
 * 1) Must be called with preemption disabled
 * 2) softirqs must be disabled too (or we should use this_cpu_add())
 */


static inline void xt_write_recseq_end(unsigned int addend)
{
	/* this is kind of a write_seqcount_end(), but addend is 0 or 1 */
	smp_wmb();
	__this_cpu_add(xt_recseq.sequence, addend);
}

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/*
 * This helper is performance critical and must be inlined
 */


static inline unsigned long ifname_compare_aligned(const char *_a,
						   const char *_b,
						   const char *_mask)
{
	const unsigned long *a = (const unsigned long *)_a;
	const unsigned long *b = (const unsigned long *)_b;
	const unsigned long *mask = (const unsigned long *)_mask;
	unsigned long ret;

	ret = (a[0] ^ b[0]) & mask[0];
	if (IFNAMSIZ > sizeof(unsigned long))
		ret |= (a[1] ^ b[1]) & mask[1];
	if (IFNAMSIZ > 2 * sizeof(unsigned long))
		ret |= (a[2] ^ b[2]) & mask[2];
	if (IFNAMSIZ > 3 * sizeof(unsigned long))
		ret |= (a[3] ^ b[3]) & mask[3];
	BUILD_BUG_ON(IFNAMSIZ > 4 * sizeof(unsigned long));
	return ret;
}


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/* On SMP, ip(6)t_entry->counters.pcnt holds address of the
 * real (percpu) counter.  On !SMP, its just the packet count,
 * so nothing needs to be done there.
 *
 * xt_percpu_counter_alloc returns the address of the percpu
 * counter, or 0 on !SMP. We force an alignment of 16 bytes
 * so that bytes/packets share a common cache line.
 *
 * Hence caller must use IS_ERR_VALUE to check for error, this
 * allows us to return 0 for single core systems without forcing
 * callers to deal with SMP vs. NONSMP issues.
 */


static inline unsigned long xt_percpu_counter_alloc(void)
{
	if (nr_cpu_ids > 1) {
		void __percpu *res = __alloc_percpu(sizeof(struct xt_counters),
						    sizeof(struct xt_counters));

		if (res == NULL)
			return -ENOMEM;

		return (__force unsigned long) res;
	}

	return 0;
}
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static inline void xt_percpu_counter_free(u64 pcnt)
{
	if (nr_cpu_ids > 1)
		free_percpu((void __percpu *) (unsigned long) pcnt);
}

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static inline struct xt_counters *

xt_get_this_cpu_counter(struct xt_counters *cnt)
{
	if (nr_cpu_ids > 1)
		return this_cpu_ptr((void __percpu *) (unsigned long) cnt->pcnt);

	return cnt;
}

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static inline struct xt_counters *

xt_get_per_cpu_counter(struct xt_counters *cnt, unsigned int cpu)
{
	if (nr_cpu_ids > 1)
		return per_cpu_ptr((void __percpu *) (unsigned long) cnt->pcnt, cpu);

	return cnt;
}

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struct nf_hook_ops *xt_hook_ops_alloc(const struct xt_table *, nf_hookfn *);

#ifdef CONFIG_COMPAT
#include <net/compat.h>


struct compat_xt_entry_match {
	union {
		struct {
			
u_int16_t match_size;
			
char name[XT_FUNCTION_MAXNAMELEN - 1];
			
u_int8_t revision;
		} 
user;
		struct {
			
u_int16_t match_size;
			
compat_uptr_t match;
		} 
kernel;
		
u_int16_t match_size;
	} 
u;
	
unsigned char data[0];
};


struct compat_xt_entry_target {
	union {
		struct {
			
u_int16_t target_size;
			
char name[XT_FUNCTION_MAXNAMELEN - 1];
			
u_int8_t revision;
		} 
user;
		struct {
			
u_int16_t target_size;
			
compat_uptr_t target;
		} 
kernel;
		
u_int16_t target_size;
	} 
u;
	
unsigned char data[0];
};

/* FIXME: this works only on 32 bit tasks
 * need to change whole approach in order to calculate align as function of
 * current task alignment */


struct compat_xt_counters {
	

compat_u64 pcnt, bcnt;			/* Packet and byte counters */
};


struct compat_xt_counters_info {
	
char name[XT_TABLE_MAXNAMELEN];
	
compat_uint_t num_counters;
	
struct compat_xt_counters counters[0];
};


struct _compat_xt_align {
	
__u8 u8;
	
__u16 u16;
	
__u32 u32;
	
compat_u64 u64;
};


#define COMPAT_XT_ALIGN(s) __ALIGN_KERNEL((s), __alignof__(struct _compat_xt_align))

void xt_compat_lock(u_int8_t af);
void xt_compat_unlock(u_int8_t af);

int xt_compat_add_offset(u_int8_t af, unsigned int offset, int delta);
void xt_compat_flush_offsets(u_int8_t af);
void xt_compat_init_offsets(u_int8_t af, unsigned int number);
int xt_compat_calc_jump(u_int8_t af, unsigned int offset);

int xt_compat_match_offset(const struct xt_match *match);
void xt_compat_match_from_user(struct xt_entry_match *m, void **dstptr,
			      unsigned int *size);
int xt_compat_match_to_user(const struct xt_entry_match *m,
			    void __user **dstptr, unsigned int *size);

int xt_compat_target_offset(const struct xt_target *target);
void xt_compat_target_from_user(struct xt_entry_target *t, void **dstptr,
				unsigned int *size);
int xt_compat_target_to_user(const struct xt_entry_target *t,
			     void __user **dstptr, unsigned int *size);
int xt_compat_check_entry_offsets(const void *base, const char *elems,
				  unsigned int target_offset,
				  unsigned int next_offset);

#endif /* CONFIG_COMPAT */
#endif /* _X_TABLES_H */
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Directory: include/linux/netfilter

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