path: root/net/netfilter/nf_log_syslog.c

// 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_bridge.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,
		},
	},
};

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

/* Guard against containers flooding syslog. */
static bool nf_log_allowed(const struct net *net)
{
	return net_eq(net, &init_net) || sysctl_nf_log_all_netns;
}

static void nf_log_dump_vlan(struct nf_log_buf *m, const struct sk_buff *skb)
{
	u16 vid;

	if (!skb_vlan_tag_present(skb))
		return;

	vid = skb_vlan_tag_get(skb);
	nf_log_buf_add(m, "VPROTO=%04x VID=%u ", ntohs(skb->vlan_proto), vid);
}
static void noinline_for_stack
dump_arp_packet(struct nf_log_buf *m,
		const struct nf_loginfo *info,
		const struct sk_buff *skb, unsigned int nhoff)
{
	const struct arppayload *ap;
	struct arppayload _arpp;
	const struct arphdr *ah;
	unsigned int logflags;
	struct arphdr _arph;

	ah = skb_header_pointer(skb, nhoff, sizeof(_arph), &_arph);
	if (!ah) {
		nf_log_buf_add(m, "TRUNCATED");
		return;
	}

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

	if (logflags & NF_LOG_MACDECODE) {
		nf_log_buf_add(m, "MACSRC=%pM MACDST=%pM ",
			       eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest);
		nf_log_dump_vlan(m, skb);
		nf_log_buf_add(m, "MACPROTO=%04x ",
			       ntohs(eth_hdr(skb)->h_proto));
	}

	nf_log_buf_add(m, "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(ARPHRD_ETHER) ||
	    ah->ar_hln != ETH_ALEN ||
	    ah->ar_pln != sizeof(__be32))
		return;

	ap = skb_header_pointer(skb, nhoff + sizeof(_arph), sizeof(_arpp), &_arpp);
	if (!ap) {
		nf_log_buf_add(m, " INCOMPLETE [%zu bytes]",
			       skb->len - sizeof(_arph));
		return;
	}
	nf_log_buf_add(m, " MACSRC=%pM IPSRC=%pI4 MACDST=%pM IPDST=%pI4",
		       ap->mac_src, ap->ip_src, ap->mac_dst, ap->ip_dst);
}

static void
nf_log_dump_packet_common(struct nf_log_buf *m, u8 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 net *net)
{
	const struct net_device *physoutdev __maybe_unused;
	const struct net_device *physindev __maybe_unused;

	nf_log_buf_add(m, KERN_SOH "%c%sIN=%s OUT=%s ",
		       '0' + loginfo->u.log.level, prefix,
			in ? in->name : "",
			out ? out->name : "");
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
	physindev = nf_bridge_get_physindev(skb, net);
	if (physindev && in != physindev)
		nf_log_buf_add(m, "PHYSIN=%s ", physindev->name);
	physoutdev = nf_bridge_get_physoutdev(skb);
	if (physoutdev && out != physoutdev)
		nf_log_buf_add(m, "PHYSOUT=%s ", physoutdev->name);
#endif
}

static void nf_log_arp_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;

	if (!nf_log_allowed(net))
		return;

	m = nf_log_buf_open();

	if (!loginfo