arp_tables.h

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/*
 *  Format of an ARP firewall descriptor
 *
 *  src, tgt, src_mask, tgt_mask, arpop, arpop_mask are always stored in
 *  network byte order.
 *  flags are stored in host byte order (of course).
 */

#ifndef _UAPI_ARPTABLES_H
#define _UAPI_ARPTABLES_H

#include <linux/types.h>
#include <linux/compiler.h>
#include <linux/netfilter_arp.h>

#include <linux/netfilter/x_tables.h>

#ifndef __KERNEL__
#define ARPT_FUNCTION_MAXNAMELEN XT_FUNCTION_MAXNAMELEN
#define ARPT_TABLE_MAXNAMELEN XT_TABLE_MAXNAMELEN
#define arpt_entry_target xt_entry_target
#define arpt_standard_target xt_standard_target
#define arpt_error_target xt_error_target
#define ARPT_CONTINUE XT_CONTINUE
#define ARPT_RETURN XT_RETURN
#define arpt_counters_info xt_counters_info
#define arpt_counters xt_counters
#define ARPT_STANDARD_TARGET XT_STANDARD_TARGET
#define ARPT_ERROR_TARGET XT_ERROR_TARGET
#define ARPT_ENTRY_ITERATE(entries, size, fn, args...) \
    XT_ENTRY_ITERATE(struct arpt_entry, entries, size, fn, ## args)
#endif

#define ARPT_DEV_ADDR_LEN_MAX 16

struct arpt_devaddr_info {
    char addr[ARPT_DEV_ADDR_LEN_MAX];
    char mask[ARPT_DEV_ADDR_LEN_MAX];
};

/* Yes, Virginia, you have to zero the padding. */
struct arpt_arp {
    /* Source and target IP addr */
    struct in_addr src, tgt;
    /* Mask for src and target IP addr */
    struct in_addr smsk, tmsk;

    /* Device hw address length, src+target device addresses */
    __u8 arhln, arhln_mask;
    struct arpt_devaddr_info src_devaddr;
    struct arpt_devaddr_info tgt_devaddr;

    /* ARP operation code. */
    __be16 arpop, arpop_mask;

    /* ARP hardware address and protocol address format. */
    __be16 arhrd, arhrd_mask;
    __be16 arpro, arpro_mask;

    /* The protocol address length is only accepted if it is 4
     * so there is no use in offering a way to do filtering on it.
     */

    char iniface[IFNAMSIZ], outiface[IFNAMSIZ];
    unsigned char iniface_mask[IFNAMSIZ], outiface_mask[IFNAMSIZ];

    /* Flags word */
    __u8 flags;
    /* Inverse flags */
    __u16 invflags;
};

/* Values for "flag" field in struct arpt_ip (general arp structure).
 * No flags defined yet.
 */
#define ARPT_F_MASK     0x00    /* All possible flag bits mask. */

/* Values for "inv" field in struct arpt_arp. */
#define ARPT_INV_VIA_IN     0x0001  /* Invert the sense of IN IFACE. */
#define ARPT_INV_VIA_OUT    0x0002  /* Invert the sense of OUT IFACE */
#define ARPT_INV_SRCIP      0x0004  /* Invert the sense of SRC IP. */
#define ARPT_INV_TGTIP      0x0008  /* Invert the sense of TGT IP. */
#define ARPT_INV_SRCDEVADDR 0x0010  /* Invert the sense of SRC DEV ADDR. */
#define ARPT_INV_TGTDEVADDR 0x0020  /* Invert the sense of TGT DEV ADDR. */
#define ARPT_INV_ARPOP      0x0040  /* Invert the sense of ARP OP. */
#define ARPT_INV_ARPHRD     0x0080  /* Invert the sense of ARP HRD. */
#define ARPT_INV_ARPPRO     0x0100  /* Invert the sense of ARP PRO. */
#define ARPT_INV_ARPHLN     0x0200  /* Invert the sense of ARP HLN. */
#define ARPT_INV_MASK       0x03FF  /* All possible flag bits mask. */

/* This structure defines each of the firewall rules.  Consists of 3
   parts which are 1) general ARP header stuff 2) match specific
   stuff 3) the target to perform if the rule matches */
struct arpt_entry
{
    struct arpt_arp arp;

    /* Size of arpt_entry + matches */
    __u16 target_offset;
    /* Size of arpt_entry + matches + target */
    __u16 next_offset;

    /* Back pointer */
    unsigned int comefrom;

    /* Packet and byte counters. */
    struct xt_counters counters;

    /* The matches (if any), then the target. */
    unsigned char elems[0];
};

/*
 * New IP firewall options for [gs]etsockopt at the RAW IP level.
 * Unlike BSD Linux inherits IP options so you don't have to use a raw
 * socket for this. Instead we check rights in the calls.
 *
 * ATTENTION: check linux/in.h before adding new number here.
 */
#define ARPT_BASE_CTL       96

#define ARPT_SO_SET_REPLACE     (ARPT_BASE_CTL)
#define ARPT_SO_SET_ADD_COUNTERS    (ARPT_BASE_CTL + 1)
#define ARPT_SO_SET_MAX         ARPT_SO_SET_ADD_COUNTERS

#define ARPT_SO_GET_INFO        (ARPT_BASE_CTL)
#define ARPT_SO_GET_ENTRIES     (ARPT_BASE_CTL + 1)
/* #define ARPT_SO_GET_REVISION_MATCH   (APRT_BASE_CTL + 2) */
#define ARPT_SO_GET_REVISION_TARGET (ARPT_BASE_CTL + 3)
#define ARPT_SO_GET_MAX         (ARPT_SO_GET_REVISION_TARGET)

/* The argument to ARPT_SO_GET_INFO */
struct arpt_getinfo {
    /* Which table: caller fills this in. */
    char name[XT_TABLE_MAXNAMELEN];

    /* Kernel fills these in. */
    /* Which hook entry points are valid: bitmask */
    unsigned int valid_hooks;

    /* Hook entry points: one per netfilter hook. */
    unsigned int hook_entry[NF_ARP_NUMHOOKS];

    /* Underflow points. */
    unsigned int underflow[NF_ARP_NUMHOOKS];

    /* Number of entries */
    unsigned int num_entries;

    /* Size of entries. */
    unsigned int size;
};

/* The argument to ARPT_SO_SET_REPLACE. */
struct arpt_replace {
    /* Which table. */
    char name[XT_TABLE_MAXNAMELEN];

    /* Which hook entry points are valid: bitmask.  You can't
           change this. */
    unsigned int valid_hooks;

    /* Number of entries */
    unsigned int num_entries;

    /* Total size of new entries */
    unsigned int size;

    /* Hook entry points. */
    unsigned int hook_entry[NF_ARP_NUMHOOKS];

    /* Underflow points. */
    unsigned int underflow[NF_ARP_NUMHOOKS];

    /* Information about old entries: */
    /* Number of counters (must be equal to current number of entries). */
    unsigned int num_counters;
    /* The old entries' counters. */
    struct xt_counters __user *counters;

    /* The entries (hang off end: not really an array). */
    struct arpt_entry entries[0];
};

/* The argument to ARPT_SO_GET_ENTRIES. */
struct arpt_get_entries {
    /* Which table: user fills this in. */
    char name[XT_TABLE_MAXNAMELEN];

    /* User fills this in: total entry size. */
    unsigned int size;

    /* The entries. */
    struct arpt_entry entrytable[0];
};

/* Helper functions */
static __inline__ struct xt_entry_target *arpt_get_target(struct arpt_entry *e)
{
    return (void *)e + e->target_offset;
}

/*
 *  Main firewall chains definitions and global var's definitions.
 */
#endif /* _UAPI_ARPTABLES_H */