// SPDX-License-Identifier: GPL-2.0-only
/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/ip.h>
#include <net/ipv6.h>
#include <net/icmp.h>
#include <net/udp.h>
#include <net/tcp.h>
#include <net/route.h>

#include <linux/netfilter.h>
#include <linux/netfilter_ipv6.h>
#include <linux/netfilter/xt_LOG.h>
#include <net/netfilter/nf_log.h>

static const struct nf_loginfo default_loginfo = {
	.type	= NF_LOG_TYPE_LOG,
	.u = {
		.log = {
			.level	  = LOGLEVEL_NOTICE,
			.logflags = NF_LOG_DEFAULT_MASK,
		},
	},
};

/* One level of recursion won't kill us */
static void dump_ipv6_packet(struct net *net, struct nf_log_buf *m,
			     const struct nf_loginfo *info,
			     const struct sk_buff *skb, unsigned int ip6hoff,
			     int recurse)
{
	u_int8_t currenthdr;
	int fragment;
	struct ipv6hdr _ip6h;
	const struct ipv6hdr *ih;
	unsigned int ptr;
	unsigned int hdrlen = 0;
	unsigned int logflags;

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

	ih = skb_header_pointer(skb, ip6hoff, sizeof(_ip6h), &_ip6h);
	if (ih == NULL) {
		nf_log_buf_add(m, "TRUNCATED");
		return;
	}

	/* Max length: 88 "SRC=0000.0000.0000.0000.0000.0000.0000.0000 DST=0000.0000.0000.0000.0000.0000.0000.0000 " */
	nf_log_buf_add(m, "SRC=%pI6 DST=%pI6 ", &ih->saddr, &ih->daddr);

	/* Max length: 44 "LEN=65535 TC=255 HOPLIMIT=255 FLOWLBL=FFFFF " */
	nf_log_buf_add(m, "LEN=%zu TC=%u HOPLIMIT=%u FLOWLBL=%u ",
	       ntohs(ih->payload_len) + sizeof(struct ipv6hdr),
	       (ntohl(*(__be32 *)ih) & 0x0ff00000) >> 20,
	       ih->hop_limit,
	       (ntohl(*(__be32 *)ih) & 0x000fffff));

	fragment = 0;
	ptr = ip6hoff + sizeof(struct ipv6hdr);
	currenthdr = ih->nexthdr;
	while (currenthdr != NEXTHDR_NONE && nf_ip6_ext_hdr(currenthdr)) {
		struct ipv6_opt_hdr _hdr;
		const struct ipv6_opt_hdr *hp;

		hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr);
		if (hp == NULL) {
			nf_log_buf_add(m, "TRUNCATED");
			return;
		}

		/* Max length: 48 "OPT (...) " */
		if (logflags & NF_LOG_IPOPT)
			nf_log_buf_add(m, "OPT ( ");

		switch (currenthdr) {
		case IPPROTO_FRAGMENT: {
			struct frag_hdr _fhdr;
			const struct frag_hdr *fh;

			nf_log_buf_add(m, "FRAG:");
			fh = skb_header_pointer(skb, ptr, sizeof(_fhdr),
						&_fhdr);
			if (fh == NULL) {
				nf_log_buf_add(m, "TRUNCATED ");
				return;
			}

			/* Max length: 6 "65535 " */
			nf_log_buf_add(m, "%u ", ntohs(fh->frag_off) & 0xFFF8);

			/* Max length: 11 "INCOMPLETE " */
			if (fh->frag_off & htons(0x0001))
				nf_log_buf_add(m, "INCOMPLETE ");

			nf_log_buf_add(m, "ID:%08x ",
				       ntohl(fh->identification));

			if (ntohs(fh->frag_off) & 0xFFF8)
				fragment = 1;

			hdrlen = 8;

			break;
		}
		case IPPROTO_DSTOPTS:
		case IPPROTO_ROUTING:
		case IPPROTO_HOPOPTS:
			if (fragment) {
				if (logflags & NF_LOG_IPOPT)
					nf_log_buf_add(m, ")");
				return;
			}
			hdrlen = ipv6_optlen(hp);
			break;
		/* Max Length */
		case IPPROTO_AH:
			if (logflags & NF_LOG_IPOPT) {
				struct ip_auth_hdr _ahdr;
				const struct ip_auth_hdr *ah;

				/* Max length: 3 "AH " */
				nf_log_buf_add(m, "AH ");

				if (fragment) {
					nf_log_buf_add(m, ")");
					return;
				}

				ah = skb_header_pointer(skb, ptr, sizeof(_ahdr),
							&_ahdr);
				if (ah == NULL) {
					/*
					 * Max length: 26 "INCOMPLETE [65535
					 *  bytes] )"
					 */
					nf_log_buf_add(m, "INCOMPLETE [%u bytes] )",
						       skb->len - ptr);
					return;
				}

				/* Length: 15 "SPI=0xF1234567 */
				nf_log_buf_add(m, "SPI=0x%x ", ntohl(ah->spi));

			}

			hdrlen = ipv6_authlen(hp);
			break;
		case IPPROTO_ESP:
			if (logflags & NF_LOG_IPOPT) {
				struct ip_esp_hdr _esph;
				const struct ip_esp_hdr *eh;

				/* Max length: 4 "ESP " */
				nf_log_buf_add(m, "ESP ");

				if (fragment) {
					nf_log_buf_add(m, ")");
					return;
				}

				/*
				 * Max length: 26 "INCOMPLETE [65535 bytes] )"
				 */
				eh = skb_header_pointer(skb, ptr, sizeof(_esph),
							&_esph);
				if (eh == NULL) {
					nf_log_buf_add(m, "INCOMPLETE [%u bytes] )",
						       skb->len - ptr);
					return;
				}

				/* Length: 16 "SPI=0xF1234567 )" */
				nf_log_buf_add(m, "SPI=0x%x )",
					       ntohl(eh->spi));
			}
			return;
		default:
			/* Max length: 20 "Unknown Ext Hdr 255" */
			nf_log_buf_add(m, "Unknown Ext Hdr %u", currenthdr);
			return;
		}
		if (logflags & NF_LOG_IPOPT)
			nf_log_buf_add(m, ") ");

		currenthdr = hp->nexthdr;
		ptr += hdrlen;
	}

	switch (currenthdr) {
	case IPPROTO_TCP:
		if (nf_log_dump_tcp_header(m, skb, currenthdr, fragment,
					   ptr, logflags))
			return;
		break;
	case IPPROTO_UDP:
	case IPPROTO_UDPLITE:
		if (nf_log_dump_udp_header(m, skb, currenthdr, fragment, ptr))
			return;
		break;
	case IPPROTO_ICMPV6: {
		struct icmp6hdr _icmp6h;
		const struct icmp6hdr *ic;

		/* Max length: 13 "PROTO=ICMPv6 " */
		nf_log_buf_add(m, "PROTO=ICMPv6 ");

		if (fragment)
			break;

		/* Max length: 25 "INCOMPLETE [65535 bytes] " */
		ic = skb_header_pointer(skb, ptr, sizeof(_icmp6h), &_icmp6h);
		if (ic == NULL) {
			nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
				       skb->len - ptr);
			return;
		}

		/* Max length: 18 "TYPE=255 CODE=255 " */
		nf_log_buf_add(m, "TYPE=%u CODE=%u ",
			       ic->icmp6_type, ic->icmp6_code);

		switch (ic->icmp6_type) {
		case ICMPV6_ECHO_REQUEST:
		case ICMPV6_ECHO_REPLY:
			/* Max length: 19 "ID=65535 SEQ=65535 " */
			nf_log_buf_add(m, "ID=%u SEQ=%u ",
				ntohs(ic->icmp6_identifier),
				ntohs(ic->icmp6_sequence));
			break;
		case ICMPV6_MGM_QUERY:
		case ICMPV6_MGM_REPORT:
		case ICMPV6_MGM_REDUCTION:
			break;

		case ICMPV6_PARAMPROB:
			/* Max length: 17 "POINTER=ffffffff " */
			nf_log_buf_add(m, "POINTER=%08x ",
				       ntohl(ic->icmp6_pointer));
			fallthrough;
		case ICMPV6_DEST_UNREACH:
		case ICMPV6_PKT_TOOBIG:
		case ICMPV6_TIME_EXCEED:
			/* Max length: 3+maxlen */
			if (recurse) {
				nf_log_buf_add(m, "[");
				dump_ipv6_packet(net, m, info, skb,
						 ptr + sizeof(_icmp6h), 0);
				nf_log_buf_add(m, "] ");
			}

			/* Max length: 10 "MTU=65535 " */
			if (ic->icmp6_type == ICMPV6_PKT_TOOBIG) {
				nf_log_buf_add(m, "MTU=%u ",
					       ntohl(ic->icmp6_mtu));
			}
		}
		break;
	}
	/* Max length: 10 "PROTO=255 " */
	default:
		nf_log_buf_add(m, "PROTO=%u ", currenthdr);
	}

	/* Max length: 15 "UID=4294967295 " */
	if ((logflags & NF_LOG_UID) && recurse)
		nf_log_dump_sk_uid_gid(net, m, skb->sk);

	/* Max length: 16 "MARK=0xFFFFFFFF " */
	if (recurse && skb->mark)
		nf_log_buf_add(m, "MARK=0x%x ", skb->mark);
}

static void dump_ipv6_mac_header(struct nf_log_buf *m,
				 const struct nf_loginfo *info,
				 const struct sk_buff *skb)
{
	struct net_device *dev = skb->dev;
	unsigned int logflags = 0;

	if (info->type == NF_LOG_TYPE_LOG)
		logflags = info->u.log.logflags;

	if (!(logflags & NF_LOG_MACDECODE))
		goto fallback;

	switch (dev->type) {
	case ARPHRD_ETHER:
		nf_log_buf_add(m, "MACSRC=%pM MACDST=%pM MACPROTO=%04x ",
		       eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
		       ntohs(eth_hdr(skb)->h_proto));
		return;
	default:
		break;
	}

fallback:
	nf_log_buf_add(m, "MAC=");
	if (dev->hard_header_len &&
	    skb->mac_header != skb->network_header) {
		const unsigned char *p = skb_mac_header(skb);
		unsigned int len = dev->hard_header_len;
		unsigned int i;

		if (dev->type == ARPHRD_SIT) {
			p -= ETH_HLEN;

			if (p < skb->head)
				p = NULL;
		}

		if (p != NULL) {
			nf_log_buf_add(m, "%02x", *p++);
			for (i = 1; i < len; i++)
				nf_log_buf_add(m, ":%02x", *p++);
		}
		nf_log_buf_add(m, " ");

		if (dev->type == ARPHRD_SIT) {
			const struct iphdr *iph =
				(struct iphdr *)skb_mac_header(skb);
			nf_log_buf_add(m, "TUNNEL=%pI4->%pI4 ", &iph->saddr,
				       &iph->daddr);
		}
	} else {
		nf_log_buf_add(m, " ");
	}
}

static void nf_log_ip6_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)
{
	struct nf_log_buf *m;

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

	m = nf_log_buf_open();

	if (!loginfo)
		loginfo = &default_loginfo;

	nf_log_dump_packet_common(m, pf, hooknum, skb, in, out,
				  loginfo, prefix);

	if (in != NULL)
		dump_ipv6_mac_header(m, loginfo, skb);

	dump_ipv6_packet(net, m, loginfo, skb, skb_network_offset(skb), 1);

	nf_log_buf_close(m);
}

static struct nf_logger nf_ip6_logger __read_mostly = {
	.name		= "nf_log_ipv6",
	.type		= NF_LOG_TYPE_LOG,
	.logfn		= nf_log_ip6_packet,
	.me		= THIS_MODULE,
};

static int __net_init nf_log_ipv6_net_init(struct net *net)
{
	return nf_log_set(net, NFPROTO_IPV6, &nf_ip6_logger);
}

static void __net_exit nf_log_ipv6_net_exit(struct net *net)
{
	nf_log_unset(net, &nf_ip6_logger);
}

static struct pernet_operations nf_log_ipv6_net_ops = {
	.init = nf_log_ipv6_net_init,
	.exit = nf_log_ipv6_net_exit,
};

static int __init nf_log_ipv6_init(void)
{
	int ret;

	ret = register_pernet_subsys(&nf_log_ipv6_net_ops);
	if (ret < 0)
		return ret;

	ret = nf_log_register(NFPROTO_IPV6, &nf_ip6_logger);
	if (ret < 0) {
		pr_err("failed to register logger\n");
		goto err1;
	}

	return 0;

err1:
	unregister_pernet_subsys(&nf_log_ipv6_net_ops);
	return ret;
}

static void __exit nf_log_ipv6_exit(void)
{
	unregister_pernet_subsys(&nf_log_ipv6_net_ops);
	nf_log_unregister(&nf_ip6_logger);
}

module_init(nf_log_ipv6_init);
module_exit(nf_log_ipv6_exit);

MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
MODULE_DESCRIPTION("Netfilter IPv6 packet logging");
MODULE_LICENSE("GPL");
MODULE_ALIAS_NF_LOGGER(AF_INET6, 0);
