// SPDX-License-Identifier: GPL-2.0-only
/* Kernel module to match the bridge port in and
 * out device for IP packets coming into contact with a bridge. */

/* (C) 2001-2003 Bart De Schuymer <bdschuym@pandora.be>
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/if.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netfilter_bridge.h>
#include <linux/netfilter/x_tables.h>
#include <uapi/linux/netfilter/xt_physdev.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
MODULE_DESCRIPTION("Xtables: Bridge physical device match");
MODULE_ALIAS("ipt_physdev");
MODULE_ALIAS("ip6t_physdev");


static bool
physdev_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
        const struct xt_physdev_info *info = par->matchinfo;
        const struct net_device *physdev;
        unsigned long ret;
        const char *indev, *outdev;

        /* Not a bridged IP packet or no info available yet:
         * LOCAL_OUT/mangle and LOCAL_OUT/nat don't know if
         * the destination device will be a bridge. */
        if (!nf_bridge_info_exists(skb)) {
                /* Return MATCH if the invert flags of the used options are on */
                if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
                    !(info->invert & XT_PHYSDEV_OP_BRIDGED))
                        return false;
                if ((info->bitmask & XT_PHYSDEV_OP_ISIN) &&
                    !(info->invert & XT_PHYSDEV_OP_ISIN))
                        return false;
                if ((info->bitmask & XT_PHYSDEV_OP_ISOUT) &&
                    !(info->invert & XT_PHYSDEV_OP_ISOUT))
                        return false;
                if ((info->bitmask & XT_PHYSDEV_OP_IN) &&
                    !(info->invert & XT_PHYSDEV_OP_IN))
                        return false;
                if ((info->bitmask & XT_PHYSDEV_OP_OUT) &&
                    !(info->invert & XT_PHYSDEV_OP_OUT))
                        return false;
                return true;
        }

        physdev = nf_bridge_get_physoutdev(skb);
        outdev = physdev ? physdev->name : NULL;

        /* This only makes sense in the FORWARD and POSTROUTING chains */
        if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
            (!!outdev ^ !(info->invert & XT_PHYSDEV_OP_BRIDGED)))
                return false;

        physdev = nf_bridge_get_physindev(skb, xt_net(par));
        indev = physdev ? physdev->name : NULL;

        if ((info->bitmask & XT_PHYSDEV_OP_ISIN &&
            (!indev ^ !!(info->invert & XT_PHYSDEV_OP_ISIN))) ||
            (info->bitmask & XT_PHYSDEV_OP_ISOUT &&
            (!outdev ^ !!(info->invert & XT_PHYSDEV_OP_ISOUT))))
                return false;

        if (!(info->bitmask & XT_PHYSDEV_OP_IN))
                goto match_outdev;

        if (indev) {
                ret = ifname_compare_aligned(indev, info->physindev,
                                             info->in_mask);

                if (!ret ^ !(info->invert & XT_PHYSDEV_OP_IN))
                        return false;
        }

match_outdev:
        if (!(info->bitmask & XT_PHYSDEV_OP_OUT))
                return true;

        if (!outdev)
                return false;

        ret = ifname_compare_aligned(outdev, info->physoutdev, info->out_mask);

        return (!!ret ^ !(info->invert & XT_PHYSDEV_OP_OUT));
}

static int physdev_mt_check(const struct xt_mtchk_param *par)
{
        const struct xt_physdev_info *info = par->matchinfo;
        static bool brnf_probed __read_mostly;

        if (!(info->bitmask & XT_PHYSDEV_OP_MASK) ||
            info->bitmask & ~XT_PHYSDEV_OP_MASK)
                return -EINVAL;
        if (info->bitmask & (XT_PHYSDEV_OP_OUT | XT_PHYSDEV_OP_ISOUT) &&
            (!(info->bitmask & XT_PHYSDEV_OP_BRIDGED) ||
             info->invert & XT_PHYSDEV_OP_BRIDGED) &&
            par->hook_mask & (1 << NF_INET_LOCAL_OUT)) {
                pr_info_ratelimited("--physdev-out and --physdev-is-out only supported in the FORWARD and POSTROUTING chains with bridged traffic\n");
                return -EINVAL;
        }

        if (!brnf_probed) {
                brnf_probed = true;
                request_module("br_netfilter");
        }

        return 0;
}

static struct xt_match physdev_mt_reg __read_mostly = {
        .name       = "physdev",
        .revision   = 0,
        .family     = NFPROTO_UNSPEC,
        .checkentry = physdev_mt_check,
        .match      = physdev_mt,
        .matchsize  = sizeof(struct xt_physdev_info),
        .me         = THIS_MODULE,
};

static int __init physdev_mt_init(void)
{
        return xt_register_match(&physdev_mt_reg);
}

static void __exit physdev_mt_exit(void)
{
        xt_unregister_match(&physdev_mt_reg);
}

module_init(physdev_mt_init);
module_exit(physdev_mt_exit);