ebt_mark.c

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/*
 *  ebt_mark
 *
 *  Authors:
 *  Bart De Schuymer <[email protected]>
 *
 *  July, 2002
 *
 */

/* The mark target can be used in any chain,
 * I believe adding a mangle table just for marking is total overkill.
 * Marking a frame doesn't really change anything in the frame anyway.
 */

#include <linux/module.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_bridge/ebtables.h>
#include <linux/netfilter_bridge/ebt_mark_t.h>

static unsigned int
ebt_mark_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
    const struct ebt_mark_t_info *info = par->targinfo;
    int action = info->target & -16;

    if (action == MARK_SET_VALUE)
        skb->mark = info->mark;
    else if (action == MARK_OR_VALUE)
        skb->mark |= info->mark;
    else if (action == MARK_AND_VALUE)
        skb->mark &= info->mark;
    else
        skb->mark ^= info->mark;

    return info->target | ~EBT_VERDICT_BITS;
}

static int ebt_mark_tg_check(const struct xt_tgchk_param *par)
{
    const struct ebt_mark_t_info *info = par->targinfo;
    int tmp;

    tmp = info->target | ~EBT_VERDICT_BITS;
    if (BASE_CHAIN && tmp == EBT_RETURN)
        return -EINVAL;
    if (tmp < -NUM_STANDARD_TARGETS || tmp >= 0)
        return -EINVAL;
    tmp = info->target & ~EBT_VERDICT_BITS;
    if (tmp != MARK_SET_VALUE && tmp != MARK_OR_VALUE &&
        tmp != MARK_AND_VALUE && tmp != MARK_XOR_VALUE)
        return -EINVAL;
    return 0;
}
#ifdef CONFIG_COMPAT
struct compat_ebt_mark_t_info {
    compat_ulong_t mark;
    compat_uint_t target;
};

static void mark_tg_compat_from_user(void *dst, const void *src)
{
    const struct compat_ebt_mark_t_info *user = src;
    struct ebt_mark_t_info *kern = dst;

    kern->mark = user->mark;
    kern->target = user->target;
}

static int mark_tg_compat_to_user(void __user *dst, const void *src)
{
    struct compat_ebt_mark_t_info __user *user = dst;
    const struct ebt_mark_t_info *kern = src;

    if (put_user(kern->mark, &user->mark) ||
        put_user(kern->target, &user->target))
        return -EFAULT;
    return 0;
}
#endif

static struct xt_target ebt_mark_tg_reg __read_mostly = {
    .name       = "mark",
    .revision   = 0,
    .family     = NFPROTO_BRIDGE,
    .target     = ebt_mark_tg,
    .checkentry = ebt_mark_tg_check,
    .targetsize = sizeof(struct ebt_mark_t_info),
#ifdef CONFIG_COMPAT
    .compatsize = sizeof(struct compat_ebt_mark_t_info),
    .compat_from_user = mark_tg_compat_from_user,
    .compat_to_user = mark_tg_compat_to_user,
#endif
    .me     = THIS_MODULE,
};

static int __init ebt_mark_init(void)
{
    return xt_register_target(&ebt_mark_tg_reg);
}

static void __exit ebt_mark_fini(void)
{
    xt_unregister_target(&ebt_mark_tg_reg);
}

module_init(ebt_mark_init);
module_exit(ebt_mark_fini);
MODULE_DESCRIPTION("Ebtables: Packet mark modification");
MODULE_LICENSE("GPL");