netfilter: ipt_LOG/ip6t_LOG: add option to print decoded MAC header
The LOG targets print the entire MAC header as one long string, which is not
readable very well:
IN=eth0 OUT= MAC=00:15:f2:24:91:f8:00:1b:24:dc:61:e6:08:00 ...
Add an option to decode known header formats (currently just ARPHRD_ETHER devices)
in their individual fields:
IN=eth0 OUT= MACSRC=00:1b:24:dc:61:e6 MACDST=00:15:f2:24:91:f8 MACPROTO=0800 ...
IN=eth0 OUT= MACSRC=00:1b:24:dc:61:e6 MACDST=00:15:f2:24:91:f8 MACPROTO=86dd ...
The option needs to be explicitly enabled by userspace to avoid breaking
existing parsers.
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/ipv4/netfilter/ipt_LOG.c b/net/ipv4/netfilter/ipt_LOG.c
index 0a452a5..915fc17 100644
--- a/net/ipv4/netfilter/ipt_LOG.c
+++ b/net/ipv4/netfilter/ipt_LOG.c
@@ -13,6 +13,7 @@
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/skbuff.h>
+#include <linux/if_arp.h>
#include <linux/ip.h>
#include <net/icmp.h>
#include <net/udp.h>
@@ -363,6 +364,42 @@
/* maxlen = 230+ 91 + 230 + 252 = 803 */
}
+static void dump_mac_header(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 & IPT_LOG_MACDECODE))
+ goto fallback;
+
+ switch (dev->type) {
+ case ARPHRD_ETHER:
+ printk("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:
+ printk("MAC=");
+ if (dev->hard_header_len &&
+ skb->mac_header != skb->network_header) {
+ const unsigned char *p = skb_mac_header(skb);
+ unsigned int i;
+
+ printk("%02x", *p++);
+ for (i = 1; i < dev->hard_header_len; i++, p++)
+ printk(":%02x", *p);
+ }
+ printk(" ");
+}
+
static struct nf_loginfo default_loginfo = {
.type = NF_LOG_TYPE_LOG,
.u = {
@@ -404,20 +441,9 @@
}
#endif
- if (in && !out) {
- /* MAC logging for input chain only. */
- printk("MAC=");
- if (skb->dev && skb->dev->hard_header_len &&
- skb->mac_header != skb->network_header) {
- int i;
- const unsigned char *p = skb_mac_header(skb);
-
- printk("%02x", *p++);
- for (i = 1; i < skb->dev->hard_header_len; i++, p++)
- printk(":%02x", *p);
- }
- printk(" ");
- }
+ /* MAC logging for input path only. */
+ if (in && !out)
+ dump_mac_header(loginfo, skb);
dump_packet(loginfo, skb, 0);
printk("\n");