ebt_log.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 *  ebt_log
  4 *
  5 *	Authors:
  6 *	Bart De Schuymer <bdschuym@pandora.be>
  7 *	Harald Welte <laforge@netfilter.org>
  8 *
  9 *  April, 2002
 10 *
 11 */
 12#include <linux/module.h>
 13#include <linux/ip.h>
 14#include <linux/in.h>
 15#include <linux/if_arp.h>
 16#include <linux/spinlock.h>
 17#include <net/netfilter/nf_log.h>
 18#include <linux/ipv6.h>
 19#include <net/ipv6.h>
 20#include <linux/in6.h>
 21#include <linux/netfilter/x_tables.h>
 22#include <linux/netfilter_bridge/ebtables.h>
 23#include <linux/netfilter_bridge/ebt_log.h>
 24#include <linux/netfilter.h>
 25
 26static DEFINE_SPINLOCK(ebt_log_lock);
 27
 28static int ebt_log_tg_check(const struct xt_tgchk_param *par)
 29{
 30	struct ebt_log_info *info = par->targinfo;
 31
 32	if (info->bitmask & ~EBT_LOG_MASK)
 33		return -EINVAL;
 34	if (info->loglevel >= 8)
 35		return -EINVAL;
 36	info->prefix[EBT_LOG_PREFIX_SIZE - 1] = '\0';
 37	return 0;
 38}
 39
 40struct tcpudphdr {
 41	__be16 src;
 42	__be16 dst;
 43};
 44
 45struct arppayload {
 46	unsigned char mac_src[ETH_ALEN];
 47	unsigned char ip_src[4];
 48	unsigned char mac_dst[ETH_ALEN];
 49	unsigned char ip_dst[4];
 50};
 51
 52static void
 53print_ports(const struct sk_buff *skb, uint8_t protocol, int offset)
 54{
 55	if (protocol == IPPROTO_TCP ||
 56	    protocol == IPPROTO_UDP ||
 57	    protocol == IPPROTO_UDPLITE ||
 58	    protocol == IPPROTO_SCTP ||
 59	    protocol == IPPROTO_DCCP) {
 60		const struct tcpudphdr *pptr;
 61		struct tcpudphdr _ports;
 62
 63		pptr = skb_header_pointer(skb, offset,
 64					  sizeof(_ports), &_ports);
 65		if (pptr == NULL) {
 66			pr_cont(" INCOMPLETE TCP/UDP header");
 67			return;
 68		}
 69		pr_cont(" SPT=%u DPT=%u", ntohs(pptr->src), ntohs(pptr->dst));
 70	}
 71}
 72
 73static void
 74ebt_log_packet(struct net *net, u_int8_t pf, unsigned int hooknum,
 75	       const struct sk_buff *skb, const struct net_device *in,
 76	       const struct net_device *out, const struct nf_loginfo *loginfo,
 77	       const char *prefix)
 78{
 79	unsigned int bitmask;
 80
 81	/* FIXME: Disabled from containers until syslog ns is supported */
 82	if (!net_eq(net, &init_net) && !sysctl_nf_log_all_netns)
 83		return;
 84
 85	spin_lock_bh(&ebt_log_lock);
 86	printk(KERN_SOH "%c%s IN=%s OUT=%s MAC source = %pM MAC dest = %pM proto = 0x%04x",
 87	       '0' + loginfo->u.log.level, prefix,
 88	       in ? in->name : "", out ? out->name : "",
 89	       eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
 90	       ntohs(eth_hdr(skb)->h_proto));
 91
 92	if (loginfo->type == NF_LOG_TYPE_LOG)
 93		bitmask = loginfo->u.log.logflags;
 94	else
 95		bitmask = NF_LOG_DEFAULT_MASK;
 96
 97	if ((bitmask & EBT_LOG_IP) && eth_hdr(skb)->h_proto ==
 98	   htons(ETH_P_IP)) {
 99		const struct iphdr *ih;
100		struct iphdr _iph;
101
102		ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
103		if (ih == NULL) {
104			pr_cont(" INCOMPLETE IP header");
105			goto out;
106		}
107		pr_cont(" IP SRC=%pI4 IP DST=%pI4, IP tos=0x%02X, IP proto=%d",
108			&ih->saddr, &ih->daddr, ih->tos, ih->protocol);
109		print_ports(skb, ih->protocol, ih->ihl*4);
110		goto out;
111	}
112
113#if IS_ENABLED(CONFIG_BRIDGE_EBT_IP6)
114	if ((bitmask & EBT_LOG_IP6) && eth_hdr(skb)->h_proto ==
115	   htons(ETH_P_IPV6)) {
116		const struct ipv6hdr *ih;
117		struct ipv6hdr _iph;
118		uint8_t nexthdr;
119		__be16 frag_off;
120		int offset_ph;
121
122		ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
123		if (ih == NULL) {
124			pr_cont(" INCOMPLETE IPv6 header");
125			goto out;
126		}
127		pr_cont(" IPv6 SRC=%pI6 IPv6 DST=%pI6, IPv6 priority=0x%01X, Next Header=%d",
128			&ih->saddr, &ih->daddr, ih->priority, ih->nexthdr);
129		nexthdr = ih->nexthdr;
130		offset_ph = ipv6_skip_exthdr(skb, sizeof(_iph), &nexthdr, &frag_off);
131		if (offset_ph == -1)
132			goto out;
133		print_ports(skb, nexthdr, offset_ph);
134		goto out;
135	}
136#endif
137
138	if ((bitmask & EBT_LOG_ARP) &&
139	    ((eth_hdr(skb)->h_proto == htons(ETH_P_ARP)) ||
140	     (eth_hdr(skb)->h_proto == htons(ETH_P_RARP)))) {
141		const struct arphdr *ah;
142		struct arphdr _arph;
143
144		ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph);
145		if (ah == NULL) {
146			pr_cont(" INCOMPLETE ARP header");
147			goto out;
148		}
149		pr_cont(" ARP HTYPE=%d, PTYPE=0x%04x, OPCODE=%d",
150			ntohs(ah->ar_hrd), ntohs(ah->ar_pro),
151			ntohs(ah->ar_op));
152
153		/* If it's for Ethernet and the lengths are OK,
154		 * then log the ARP payload
155		 */
156		if (ah->ar_hrd == htons(1) &&
157		    ah->ar_hln == ETH_ALEN &&
158		    ah->ar_pln == sizeof(__be32)) {
159			const struct arppayload *ap;
160			struct arppayload _arpp;
161
162			ap = skb_header_pointer(skb, sizeof(_arph),
163						sizeof(_arpp), &_arpp);
164			if (ap == NULL) {
165				pr_cont(" INCOMPLETE ARP payload");
166				goto out;
167			}
168			pr_cont(" ARP MAC SRC=%pM ARP IP SRC=%pI4 ARP MAC DST=%pM ARP IP DST=%pI4",
169				ap->mac_src, ap->ip_src,
170				ap->mac_dst, ap->ip_dst);
171		}
172	}
173out:
174	pr_cont("\n");
175	spin_unlock_bh(&ebt_log_lock);
176}
177
178static unsigned int
179ebt_log_tg(struct sk_buff *skb, const struct xt_action_param *par)
180{
181	const struct ebt_log_info *info = par->targinfo;
182	struct nf_loginfo li;
183	struct net *net = xt_net(par);
184
185	li.type = NF_LOG_TYPE_LOG;
186	li.u.log.level = info->loglevel;
187	li.u.log.logflags = info->bitmask;
188
189	/* Remember that we have to use ebt_log_packet() not to break backward
190	 * compatibility. We cannot use the default bridge packet logger via
191	 * nf_log_packet() with NFT_LOG_TYPE_LOG here. --Pablo
192	 */
193	if (info->bitmask & EBT_LOG_NFLOG)
194		nf_log_packet(net, NFPROTO_BRIDGE, xt_hooknum(par), skb,
195			      xt_in(par), xt_out(par), &li, "%s",
196			      info->prefix);
197	else
198		ebt_log_packet(net, NFPROTO_BRIDGE, xt_hooknum(par), skb,
199			       xt_in(par), xt_out(par), &li, info->prefix);
200	return EBT_CONTINUE;
201}
202
203static struct xt_target ebt_log_tg_reg __read_mostly = {
204	.name		= "log",
205	.revision	= 0,
206	.family		= NFPROTO_BRIDGE,
207	.target		= ebt_log_tg,
208	.checkentry	= ebt_log_tg_check,
209	.targetsize	= sizeof(struct ebt_log_info),
210	.me		= THIS_MODULE,
211};
212
213static int __init ebt_log_init(void)
214{
215	return xt_register_target(&ebt_log_tg_reg);
216}
217
218static void __exit ebt_log_fini(void)
219{
220	xt_unregister_target(&ebt_log_tg_reg);
221}
222
223module_init(ebt_log_init);
224module_exit(ebt_log_fini);
225MODULE_DESCRIPTION("Ebtables: Packet logging to syslog");
226MODULE_LICENSE("GPL");