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>
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@ -7,7 +7,8 @@
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#define IPT_LOG_IPOPT 0x04 /* Log IP options */
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#define IPT_LOG_UID 0x08 /* Log UID owning local socket */
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#define IPT_LOG_NFLOG 0x10 /* Unsupported, don't reuse */
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#define IPT_LOG_MASK 0x1f
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#define IPT_LOG_MACDECODE 0x20 /* Decode MAC header */
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#define IPT_LOG_MASK 0x2f
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struct ipt_log_info {
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unsigned char level;
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@ -7,7 +7,8 @@
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#define IP6T_LOG_IPOPT 0x04 /* Log IP options */
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#define IP6T_LOG_UID 0x08 /* Log UID owning local socket */
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#define IP6T_LOG_NFLOG 0x10 /* Unsupported, don't use */
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#define IP6T_LOG_MASK 0x1f
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#define IP6T_LOG_MACDECODE 0x20 /* Decode MAC header */
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#define IP6T_LOG_MASK 0x2f
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struct ip6t_log_info {
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unsigned char level;
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@ -13,6 +13,7 @@
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#include <linux/module.h>
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#include <linux/spinlock.h>
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#include <linux/skbuff.h>
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#include <linux/if_arp.h>
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#include <linux/ip.h>
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#include <net/icmp.h>
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#include <net/udp.h>
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@ -363,6 +364,42 @@ static void dump_packet(const struct nf_loginfo *info,
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/* maxlen = 230+ 91 + 230 + 252 = 803 */
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}
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static void dump_mac_header(const struct nf_loginfo *info,
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const struct sk_buff *skb)
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{
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struct net_device *dev = skb->dev;
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unsigned int logflags = 0;
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if (info->type == NF_LOG_TYPE_LOG)
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logflags = info->u.log.logflags;
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if (!(logflags & IPT_LOG_MACDECODE))
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goto fallback;
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switch (dev->type) {
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case ARPHRD_ETHER:
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printk("MACSRC=%pM MACDST=%pM MACPROTO=%04x ",
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eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
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ntohs(eth_hdr(skb)->h_proto));
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return;
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default:
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break;
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}
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fallback:
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printk("MAC=");
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if (dev->hard_header_len &&
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skb->mac_header != skb->network_header) {
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const unsigned char *p = skb_mac_header(skb);
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unsigned int i;
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printk("%02x", *p++);
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for (i = 1; i < dev->hard_header_len; i++, p++)
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printk(":%02x", *p);
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}
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printk(" ");
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}
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static struct nf_loginfo default_loginfo = {
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.type = NF_LOG_TYPE_LOG,
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.u = {
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@ -404,20 +441,9 @@ ipt_log_packet(u_int8_t pf,
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}
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#endif
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if (in && !out) {
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/* MAC logging for input chain only. */
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printk("MAC=");
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if (skb->dev && skb->dev->hard_header_len &&
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skb->mac_header != skb->network_header) {
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int i;
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const unsigned char *p = skb_mac_header(skb);
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printk("%02x", *p++);
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for (i = 1; i < skb->dev->hard_header_len; i++, p++)
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printk(":%02x", *p);
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}
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printk(" ");
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}
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/* MAC logging for input path only. */
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if (in && !out)
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dump_mac_header(loginfo, skb);
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dump_packet(loginfo, skb, 0);
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printk("\n");
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@ -373,6 +373,56 @@ static void dump_packet(const struct nf_loginfo *info,
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printk("MARK=0x%x ", skb->mark);
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}
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static void dump_mac_header(const struct nf_loginfo *info,
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const struct sk_buff *skb)
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{
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struct net_device *dev = skb->dev;
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unsigned int logflags = 0;
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if (info->type == NF_LOG_TYPE_LOG)
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logflags = info->u.log.logflags;
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if (!(logflags & IP6T_LOG_MACDECODE))
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goto fallback;
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switch (dev->type) {
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case ARPHRD_ETHER:
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printk("MACSRC=%pM MACDST=%pM MACPROTO=%04x ",
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eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
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ntohs(eth_hdr(skb)->h_proto));
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return;
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default:
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break;
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}
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fallback:
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printk("MAC=");
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if (dev->hard_header_len &&
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skb->mac_header != skb->network_header) {
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const unsigned char *p = skb_mac_header(skb);
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unsigned int len = dev->hard_header_len;
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unsigned int i;
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if (dev->type == ARPHRD_SIT &&
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(p -= ETH_HLEN) < skb->head)
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p = NULL;
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if (p != NULL) {
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printk("%02x", *p++);
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for (i = 1; i < len; i++)
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printk(":%02x", p[i]);
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}
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printk(" ");
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if (dev->type == ARPHRD_SIT) {
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const struct iphdr *iph =
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(struct iphdr *)skb_mac_header(skb);
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printk("TUNNEL=%pI4->%pI4 ", &iph->saddr, &iph->daddr);
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}
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} else
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printk(" ");
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}
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static struct nf_loginfo default_loginfo = {
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.type = NF_LOG_TYPE_LOG,
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.u = {
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@ -400,35 +450,10 @@ ip6t_log_packet(u_int8_t pf,
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prefix,
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in ? in->name : "",
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out ? out->name : "");
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if (in && !out) {
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unsigned int len;
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/* MAC logging for input chain only. */
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printk("MAC=");
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if (skb->dev && (len = skb->dev->hard_header_len) &&
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skb->mac_header != skb->network_header) {
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const unsigned char *p = skb_mac_header(skb);
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int i;
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if (skb->dev->type == ARPHRD_SIT &&
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(p -= ETH_HLEN) < skb->head)
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p = NULL;
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if (p != NULL) {
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printk("%02x", *p++);
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for (i = 1; i < len; i++)
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printk(":%02x", p[i]);
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}
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printk(" ");
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if (skb->dev->type == ARPHRD_SIT) {
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const struct iphdr *iph =
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(struct iphdr *)skb_mac_header(skb);
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printk("TUNNEL=%pI4->%pI4 ",
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&iph->saddr, &iph->daddr);
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}
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} else
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printk(" ");
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}
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/* MAC logging for input path only. */
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if (in && !out)
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dump_mac_header(loginfo, skb);
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dump_packet(loginfo, skb, skb_network_offset(skb), 1);
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printk("\n");
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