// SPDX-License-Identifier: GPL-2.0-only
/*
 *  ebt_ip6
 *
 *      Authors:
 *      Manohar Castelino <manohar.r.castelino@intel.com>
 *      Kuo-Lang Tseng <kuo-lang.tseng@intel.com>
 *      Jan Engelhardt <jengelh@medozas.de>
 *
 * Summary:
 * This is just a modification of the IPv4 code written by
 * Bart De Schuymer <bdschuym@pandora.be>
 * with the changes required to support IPv6
 *
 *  Jan, 2008
 */
#include <linux/ipv6.h>
#include <net/ipv6.h>
#include <linux/in.h>
#include <linux/module.h>
#include <net/dsfield.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_bridge/ebtables.h>
#include <linux/netfilter_bridge/ebt_ip6.h>

union pkthdr {
        struct {
                __be16 src;
                __be16 dst;
        } tcpudphdr;
        struct {
                u8 type;
                u8 code;
        } icmphdr;
};

static bool
ebt_ip6_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
        const struct ebt_ip6_info *info = par->matchinfo;
        const struct ipv6hdr *ih6;
        struct ipv6hdr _ip6h;
        const union pkthdr *pptr;
        union pkthdr _pkthdr;

        ih6 = skb_header_pointer(skb, 0, sizeof(_ip6h), &_ip6h);
        if (ih6 == NULL)
                return false;
        if ((info->bitmask & EBT_IP6_TCLASS) &&
            NF_INVF(info, EBT_IP6_TCLASS,
                    info->tclass != ipv6_get_dsfield(ih6)))
                return false;
        if (((info->bitmask & EBT_IP6_SOURCE) &&
             NF_INVF(info, EBT_IP6_SOURCE,
                     ipv6_masked_addr_cmp(&ih6->saddr, &info->smsk,
                                          &info->saddr))) ||
            ((info->bitmask & EBT_IP6_DEST) &&
             NF_INVF(info, EBT_IP6_DEST,
                     ipv6_masked_addr_cmp(&ih6->daddr, &info->dmsk,
                                          &info->daddr))))
                return false;
        if (info->bitmask & EBT_IP6_PROTO) {
                uint8_t nexthdr = ih6->nexthdr;
                __be16 frag_off;
                int offset_ph;

                offset_ph = ipv6_skip_exthdr(skb, sizeof(_ip6h), &nexthdr, &frag_off);
                if (offset_ph == -1)
                        return false;
                if (NF_INVF(info, EBT_IP6_PROTO, info->protocol != nexthdr))
                        return false;
                if (!(info->bitmask & (EBT_IP6_DPORT |
                                       EBT_IP6_SPORT | EBT_IP6_ICMP6)))
                        return true;

                /* min icmpv6 headersize is 4, so sizeof(_pkthdr) is ok. */
                pptr = skb_header_pointer(skb, offset_ph, sizeof(_pkthdr),
                                          &_pkthdr);
                if (pptr == NULL)
                        return false;
                if (info->bitmask & EBT_IP6_DPORT) {
                        u16 dst = ntohs(pptr->tcpudphdr.dst);
                        if (NF_INVF(info, EBT_IP6_DPORT,
                                    dst < info->dport[0] ||
                                    dst > info->dport[1]))
                                return false;
                }
                if (info->bitmask & EBT_IP6_SPORT) {
                        u16 src = ntohs(pptr->tcpudphdr.src);
                        if (NF_INVF(info, EBT_IP6_SPORT,
                                    src < info->sport[0] ||
                                    src > info->sport[1]))
                                return false;
                }
                if ((info->bitmask & EBT_IP6_ICMP6) &&
                    NF_INVF(info, EBT_IP6_ICMP6,
                            pptr->icmphdr.type < info->icmpv6_type[0] ||
                            pptr->icmphdr.type > info->icmpv6_type[1] ||
                            pptr->icmphdr.code < info->icmpv6_code[0] ||
                            pptr->icmphdr.code > info->icmpv6_code[1]))
                        return false;
        }
        return true;
}

static int ebt_ip6_mt_check(const struct xt_mtchk_param *par)
{
        const struct ebt_entry *e = par->entryinfo;
        struct ebt_ip6_info *info = par->matchinfo;

        if (e->ethproto != htons(ETH_P_IPV6) || e->invflags & EBT_IPROTO)
                return -EINVAL;
        if (info->bitmask & ~EBT_IP6_MASK || info->invflags & ~EBT_IP6_MASK)
                return -EINVAL;
        if (info->bitmask & (EBT_IP6_DPORT | EBT_IP6_SPORT)) {
                if (info->invflags & EBT_IP6_PROTO)
                        return -EINVAL;
                if (info->protocol != IPPROTO_TCP &&
                    info->protocol != IPPROTO_UDP &&
                    info->protocol != IPPROTO_UDPLITE &&
                    info->protocol != IPPROTO_SCTP &&
                    info->protocol != IPPROTO_DCCP)
                        return -EINVAL;
        }
        if (info->bitmask & EBT_IP6_DPORT && info->dport[0] > info->dport[1])
                return -EINVAL;
        if (info->bitmask & EBT_IP6_SPORT && info->sport[0] > info->sport[1])
                return -EINVAL;
        if (info->bitmask & EBT_IP6_ICMP6) {
                if ((info->invflags & EBT_IP6_PROTO) ||
                     info->protocol != IPPROTO_ICMPV6)
                        return -EINVAL;
                if (info->icmpv6_type[0] > info->icmpv6_type[1] ||
                    info->icmpv6_code[0] > info->icmpv6_code[1])
                        return -EINVAL;
        }
        return 0;
}

static struct xt_match ebt_ip6_mt_reg __read_mostly = {
        .name           = "ip6",
        .revision       = 0,
        .family         = NFPROTO_BRIDGE,
        .match          = ebt_ip6_mt,
        .checkentry     = ebt_ip6_mt_check,
        .matchsize      = sizeof(struct ebt_ip6_info),
        .me             = THIS_MODULE,
};

static int __init ebt_ip6_init(void)
{
        return xt_register_match(&ebt_ip6_mt_reg);
}

static void __exit ebt_ip6_fini(void)
{
        xt_unregister_match(&ebt_ip6_mt_reg);
}

module_init(ebt_ip6_init);
module_exit(ebt_ip6_fini);
MODULE_DESCRIPTION("Ebtables: IPv6 protocol packet match");
MODULE_AUTHOR("Kuo-Lang Tseng <kuo-lang.tseng@intel.com>");
MODULE_LICENSE("GPL");