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 len: sizeof(_ports), buffer: &_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(net1: net, net2: &init_net) && !sysctl_nf_log_all_netns)
83 return;
84
85 spin_lock_bh(lock: &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, offset: 0, len: sizeof(_iph), buffer: &_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, protocol: ih->protocol, offset: 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, offset: 0, len: sizeof(_iph), buffer: &_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, start: sizeof(_iph), nexthdrp: &nexthdr, frag_offp: &frag_off);
131 if (offset_ph == -1)
132 goto out;
133 print_ports(skb, protocol: nexthdr, offset: 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, offset: 0, len: sizeof(_arph), buffer: &_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, offset: sizeof(_arph),
163 len: sizeof(_arpp), buffer: &_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(lock: &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, pf: NFPROTO_BRIDGE, hooknum: xt_hooknum(par), skb,
195 in: xt_in(par), out: xt_out(par), li: &li, fmt: "%s",
196 info->prefix);
197 else
198 ebt_log_packet(net, pf: NFPROTO_BRIDGE, hooknum: xt_hooknum(par), skb,
199 in: xt_in(par), out: xt_out(par), loginfo: &li, prefix: 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(target: &ebt_log_tg_reg);
216}
217
218static void __exit ebt_log_fini(void)
219{
220 xt_unregister_target(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");
227

source code of linux/net/bridge/netfilter/ebt_log.c