// SPDX-License-Identifier: GPL-2.0-only
/*
 *  ebt_log
 *
 *      Authors:
 *      Bart De Schuymer <bdschuym@pandora.be>
 *      Harald Welte <laforge@netfilter.org>
 *
 *  April, 2002
 *
 */
#include <linux/module.h>
#include <linux/ip.h>
#include <linux/in.h>
#include <linux/if_arp.h>
#include <linux/spinlock.h>
#include <net/netfilter/nf_log.h>
#include <linux/ipv6.h>
#include <net/ipv6.h>
#include <linux/in6.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_bridge/ebtables.h>
#include <linux/netfilter_bridge/ebt_log.h>
#include <linux/netfilter.h>

static DEFINE_SPINLOCK(ebt_log_lock);

static int ebt_log_tg_check(const struct xt_tgchk_param *par)
{
        struct ebt_log_info *info = par->targinfo;

        if (info->bitmask & ~EBT_LOG_MASK)
                return -EINVAL;
        if (info->loglevel >= 8)
                return -EINVAL;
        info->prefix[EBT_LOG_PREFIX_SIZE - 1] = '\0';
        return 0;
}

struct tcpudphdr {
        __be16 src;
        __be16 dst;
};

struct arppayload {
        unsigned char mac_src[ETH_ALEN];
        unsigned char ip_src[4];
        unsigned char mac_dst[ETH_ALEN];
        unsigned char ip_dst[4];
};

static void
print_ports(const struct sk_buff *skb, uint8_t protocol, int offset)
{
        if (protocol == IPPROTO_TCP ||
            protocol == IPPROTO_UDP ||
            protocol == IPPROTO_UDPLITE ||
            protocol == IPPROTO_SCTP ||
            protocol == IPPROTO_DCCP) {
                const struct tcpudphdr *pptr;
                struct tcpudphdr _ports;

                pptr = skb_header_pointer(skb, offset,
                                          sizeof(_ports), &_ports);
                if (pptr == NULL) {
                        pr_cont(" INCOMPLETE TCP/UDP header");
                        return;
                }
                pr_cont(" SPT=%u DPT=%u", ntohs(pptr->src), ntohs(pptr->dst));
        }
}

static void
ebt_log_packet(struct net *net, u_int8_t pf, unsigned int hooknum,
               const struct sk_buff *skb, const struct net_device *in,
               const struct net_device *out, const struct nf_loginfo *loginfo,
               const char *prefix)
{
        unsigned int bitmask;

        /* FIXME: Disabled from containers until syslog ns is supported */
        if (!net_eq(net, &init_net) && !sysctl_nf_log_all_netns)
                return;

        spin_lock_bh(&ebt_log_lock);
        printk(KERN_SOH "%c%s IN=%s OUT=%s MAC source = %pM MAC dest = %pM proto = 0x%04x",
               '0' + loginfo->u.log.level, prefix,
               in ? in->name : "", out ? out->name : "",
               eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
               ntohs(eth_hdr(skb)->h_proto));

        if (loginfo->type == NF_LOG_TYPE_LOG)
                bitmask = loginfo->u.log.logflags;
        else
                bitmask = NF_LOG_DEFAULT_MASK;

        if ((bitmask & EBT_LOG_IP) && eth_hdr(skb)->h_proto ==
           htons(ETH_P_IP)) {
                const struct iphdr *ih;
                struct iphdr _iph;

                ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
                if (ih == NULL) {
                        pr_cont(" INCOMPLETE IP header");
                        goto out;
                }
                pr_cont(" IP SRC=%pI4 IP DST=%pI4, IP tos=0x%02X, IP proto=%d",
                        &ih->saddr, &ih->daddr, ih->tos, ih->protocol);
                print_ports(skb, ih->protocol, ih->ihl*4);
                goto out;
        }

#if IS_ENABLED(CONFIG_BRIDGE_EBT_IP6)
        if ((bitmask & EBT_LOG_IP6) && eth_hdr(skb)->h_proto ==
           htons(ETH_P_IPV6)) {
                const struct ipv6hdr *ih;
                struct ipv6hdr _iph;
                uint8_t nexthdr;
                __be16 frag_off;
                int offset_ph;

                ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
                if (ih == NULL) {
                        pr_cont(" INCOMPLETE IPv6 header");
                        goto out;
                }
                pr_cont(" IPv6 SRC=%pI6 IPv6 DST=%pI6, IPv6 priority=0x%01X, Next Header=%d",
                        &ih->saddr, &ih->daddr, ih->priority, ih->nexthdr);
                nexthdr = ih->nexthdr;
                offset_ph = ipv6_skip_exthdr(skb, sizeof(_iph), &nexthdr, &frag_off);
                if (offset_ph == -1)
                        goto out;
                print_ports(skb, nexthdr, offset_ph);
                goto out;
        }
#endif

        if ((bitmask & EBT_LOG_ARP) &&
            ((eth_hdr(skb)->h_proto == htons(ETH_P_ARP)) ||
             (eth_hdr(skb)->h_proto == htons(ETH_P_RARP)))) {
                const struct arphdr *ah;
                struct arphdr _arph;

                ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph);
                if (ah == NULL) {
                        pr_cont(" INCOMPLETE ARP header");
                        goto out;
                }
                pr_cont(" ARP HTYPE=%d, PTYPE=0x%04x, OPCODE=%d",
                        ntohs(ah->ar_hrd), ntohs(ah->ar_pro),
                        ntohs(ah->ar_op));

                /* If it's for Ethernet and the lengths are OK,
                 * then log the ARP payload
                 */
                if (ah->ar_hrd == htons(1) &&
                    ah->ar_hln == ETH_ALEN &&
                    ah->ar_pln == sizeof(__be32)) {
                        const struct arppayload *ap;
                        struct arppayload _arpp;

                        ap = skb_header_pointer(skb, sizeof(_arph),
                                                sizeof(_arpp), &_arpp);
                        if (ap == NULL) {
                                pr_cont(" INCOMPLETE ARP payload");
                                goto out;
                        }
                        pr_cont(" ARP MAC SRC=%pM ARP IP SRC=%pI4 ARP MAC DST=%pM ARP IP DST=%pI4",
                                ap->mac_src, ap->ip_src,
                                ap->mac_dst, ap->ip_dst);
                }
        }
out:
        pr_cont("\n");
        spin_unlock_bh(&ebt_log_lock);
}

static unsigned int
ebt_log_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
        const struct ebt_log_info *info = par->targinfo;
        struct nf_loginfo li;
        struct net *net = xt_net(par);

        li.type = NF_LOG_TYPE_LOG;
        li.u.log.level = info->loglevel;
        li.u.log.logflags = info->bitmask;

        /* Remember that we have to use ebt_log_packet() not to break backward
         * compatibility. We cannot use the default bridge packet logger via
         * nf_log_packet() with NFT_LOG_TYPE_LOG here. --Pablo
         */
        if (info->bitmask & EBT_LOG_NFLOG)
                nf_log_packet(net, NFPROTO_BRIDGE, xt_hooknum(par), skb,
                              xt_in(par), xt_out(par), &li, "%s",
                              info->prefix);
        else
                ebt_log_packet(net, NFPROTO_BRIDGE, xt_hooknum(par), skb,
                               xt_in(par), xt_out(par), &li, info->prefix);
        return EBT_CONTINUE;
}

static struct xt_target ebt_log_tg_reg __read_mostly = {
        .name           = "log",
        .revision       = 0,
        .family         = NFPROTO_BRIDGE,
        .target         = ebt_log_tg,
        .checkentry     = ebt_log_tg_check,
        .targetsize     = sizeof(struct ebt_log_info),
        .me             = THIS_MODULE,
};

static int __init ebt_log_init(void)
{
        return xt_register_target(&ebt_log_tg_reg);
}

static void __exit ebt_log_fini(void)
{
        xt_unregister_target(&ebt_log_tg_reg);
}

module_init(ebt_log_init);
module_exit(ebt_log_fini);
MODULE_DESCRIPTION("Ebtables: Packet logging to syslog");
MODULE_LICENSE("GPL");