1 /*
2  *  ebt_log
3  *
4  *	Authors:
5  *	Bart De Schuymer <bdschuym@pandora.be>
6  *	Harald Welte <laforge@netfilter.org>
7  *
8  *  April, 2002
9  *
10  */
11 #include <linux/module.h>
12 #include <linux/ip.h>
13 #include <linux/in.h>
14 #include <linux/if_arp.h>
15 #include <linux/spinlock.h>
16 #include <net/netfilter/nf_log.h>
17 #include <linux/ipv6.h>
18 #include <net/ipv6.h>
19 #include <linux/in6.h>
20 #include <linux/netfilter/x_tables.h>
21 #include <linux/netfilter_bridge/ebtables.h>
22 #include <linux/netfilter_bridge/ebt_log.h>
23 #include <linux/netfilter.h>
24 
25 static DEFINE_SPINLOCK(ebt_log_lock);
26 
ebt_log_tg_check(const struct xt_tgchk_param * par)27 static int ebt_log_tg_check(const struct xt_tgchk_param *par)
28 {
29 	struct ebt_log_info *info = par->targinfo;
30 
31 	if (info->bitmask & ~EBT_LOG_MASK)
32 		return -EINVAL;
33 	if (info->loglevel >= 8)
34 		return -EINVAL;
35 	info->prefix[EBT_LOG_PREFIX_SIZE - 1] = '\0';
36 	return 0;
37 }
38 
39 struct tcpudphdr
40 {
41 	__be16 src;
42 	__be16 dst;
43 };
44 
45 struct arppayload
46 {
47 	unsigned char mac_src[ETH_ALEN];
48 	unsigned char ip_src[4];
49 	unsigned char mac_dst[ETH_ALEN];
50 	unsigned char ip_dst[4];
51 };
52 
53 static void
print_ports(const struct sk_buff * skb,uint8_t protocol,int offset)54 print_ports(const struct sk_buff *skb, uint8_t protocol, int offset)
55 {
56 	if (protocol == IPPROTO_TCP ||
57 	    protocol == IPPROTO_UDP ||
58 	    protocol == IPPROTO_UDPLITE ||
59 	    protocol == IPPROTO_SCTP ||
60 	    protocol == IPPROTO_DCCP) {
61 		const struct tcpudphdr *pptr;
62 		struct tcpudphdr _ports;
63 
64 		pptr = skb_header_pointer(skb, offset,
65 					  sizeof(_ports), &_ports);
66 		if (pptr == NULL) {
67 			printk(" INCOMPLETE TCP/UDP header");
68 			return;
69 		}
70 		printk(" SPT=%u DPT=%u", ntohs(pptr->src), ntohs(pptr->dst));
71 	}
72 }
73 
74 static void
ebt_log_packet(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)75 ebt_log_packet(u_int8_t pf, unsigned int hooknum,
76    const struct sk_buff *skb, const struct net_device *in,
77    const struct net_device *out, const struct nf_loginfo *loginfo,
78    const char *prefix)
79 {
80 	unsigned int bitmask;
81 
82 	spin_lock_bh(&ebt_log_lock);
83 	printk("<%c>%s IN=%s OUT=%s MAC source = %pM MAC dest = %pM proto = 0x%04x",
84 	       '0' + loginfo->u.log.level, prefix,
85 	       in ? in->name : "", out ? out->name : "",
86 	       eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
87 	       ntohs(eth_hdr(skb)->h_proto));
88 
89 	if (loginfo->type == NF_LOG_TYPE_LOG)
90 		bitmask = loginfo->u.log.logflags;
91 	else
92 		bitmask = NF_LOG_MASK;
93 
94 	if ((bitmask & EBT_LOG_IP) && eth_hdr(skb)->h_proto ==
95 	   htons(ETH_P_IP)){
96 		const struct iphdr *ih;
97 		struct iphdr _iph;
98 
99 		ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
100 		if (ih == NULL) {
101 			printk(" INCOMPLETE IP header");
102 			goto out;
103 		}
104 		printk(" IP SRC=%pI4 IP DST=%pI4, IP tos=0x%02X, IP proto=%d",
105 		       &ih->saddr, &ih->daddr, ih->tos, ih->protocol);
106 		print_ports(skb, ih->protocol, ih->ihl*4);
107 		goto out;
108 	}
109 
110 #if IS_ENABLED(CONFIG_BRIDGE_EBT_IP6)
111 	if ((bitmask & EBT_LOG_IP6) && eth_hdr(skb)->h_proto ==
112 	   htons(ETH_P_IPV6)) {
113 		const struct ipv6hdr *ih;
114 		struct ipv6hdr _iph;
115 		uint8_t nexthdr;
116 		__be16 frag_off;
117 		int offset_ph;
118 
119 		ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
120 		if (ih == NULL) {
121 			printk(" INCOMPLETE IPv6 header");
122 			goto out;
123 		}
124 		printk(" IPv6 SRC=%pI6 IPv6 DST=%pI6, IPv6 priority=0x%01X, Next Header=%d",
125 		       &ih->saddr, &ih->daddr, ih->priority, ih->nexthdr);
126 		nexthdr = ih->nexthdr;
127 		offset_ph = ipv6_skip_exthdr(skb, sizeof(_iph), &nexthdr, &frag_off);
128 		if (offset_ph == -1)
129 			goto out;
130 		print_ports(skb, nexthdr, offset_ph);
131 		goto out;
132 	}
133 #endif
134 
135 	if ((bitmask & EBT_LOG_ARP) &&
136 	    ((eth_hdr(skb)->h_proto == htons(ETH_P_ARP)) ||
137 	     (eth_hdr(skb)->h_proto == htons(ETH_P_RARP)))) {
138 		const struct arphdr *ah;
139 		struct arphdr _arph;
140 
141 		ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph);
142 		if (ah == NULL) {
143 			printk(" INCOMPLETE ARP header");
144 			goto out;
145 		}
146 		printk(" ARP HTYPE=%d, PTYPE=0x%04x, OPCODE=%d",
147 		       ntohs(ah->ar_hrd), ntohs(ah->ar_pro),
148 		       ntohs(ah->ar_op));
149 
150 		/* If it's for Ethernet and the lengths are OK,
151 		 * then log the ARP payload */
152 		if (ah->ar_hrd == htons(1) &&
153 		    ah->ar_hln == ETH_ALEN &&
154 		    ah->ar_pln == sizeof(__be32)) {
155 			const struct arppayload *ap;
156 			struct arppayload _arpp;
157 
158 			ap = skb_header_pointer(skb, sizeof(_arph),
159 						sizeof(_arpp), &_arpp);
160 			if (ap == NULL) {
161 				printk(" INCOMPLETE ARP payload");
162 				goto out;
163 			}
164 			printk(" ARP MAC SRC=%pM ARP IP SRC=%pI4 ARP MAC DST=%pM ARP IP DST=%pI4",
165 					ap->mac_src, ap->ip_src, ap->mac_dst, ap->ip_dst);
166 		}
167 	}
168 out:
169 	printk("\n");
170 	spin_unlock_bh(&ebt_log_lock);
171 
172 }
173 
174 static unsigned int
ebt_log_tg(struct sk_buff * skb,const struct xt_action_param * par)175 ebt_log_tg(struct sk_buff *skb, const struct xt_action_param *par)
176 {
177 	const struct ebt_log_info *info = par->targinfo;
178 	struct nf_loginfo li;
179 
180 	li.type = NF_LOG_TYPE_LOG;
181 	li.u.log.level = info->loglevel;
182 	li.u.log.logflags = info->bitmask;
183 
184 	if (info->bitmask & EBT_LOG_NFLOG)
185 		nf_log_packet(NFPROTO_BRIDGE, par->hooknum, skb, par->in,
186 		              par->out, &li, "%s", info->prefix);
187 	else
188 		ebt_log_packet(NFPROTO_BRIDGE, par->hooknum, skb, par->in,
189 		               par->out, &li, info->prefix);
190 	return EBT_CONTINUE;
191 }
192 
193 static struct xt_target ebt_log_tg_reg __read_mostly = {
194 	.name		= "log",
195 	.revision	= 0,
196 	.family		= NFPROTO_BRIDGE,
197 	.target		= ebt_log_tg,
198 	.checkentry	= ebt_log_tg_check,
199 	.targetsize	= sizeof(struct ebt_log_info),
200 	.me		= THIS_MODULE,
201 };
202 
203 static struct nf_logger ebt_log_logger __read_mostly = {
204 	.name 		= "ebt_log",
205 	.logfn		= &ebt_log_packet,
206 	.me		= THIS_MODULE,
207 };
208 
ebt_log_init(void)209 static int __init ebt_log_init(void)
210 {
211 	int ret;
212 
213 	ret = xt_register_target(&ebt_log_tg_reg);
214 	if (ret < 0)
215 		return ret;
216 	nf_log_register(NFPROTO_BRIDGE, &ebt_log_logger);
217 	return 0;
218 }
219 
ebt_log_fini(void)220 static void __exit ebt_log_fini(void)
221 {
222 	nf_log_unregister(&ebt_log_logger);
223 	xt_unregister_target(&ebt_log_tg_reg);
224 }
225 
226 module_init(ebt_log_init);
227 module_exit(ebt_log_fini);
228 MODULE_DESCRIPTION("Ebtables: Packet logging to syslog");
229 MODULE_LICENSE("GPL");
230