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Message-Id: <1405681272-4994-10-git-send-email-pablo@netfilter.org>
Date: Fri, 18 Jul 2014 13:01:03 +0200
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 09/18] netfilter: add generic ARP packet logger
This adds the generic plain text packet loggger for ARP packets. It is
based on the ebt_log code. Nevertheless, the output has been modified
to make it consistent with the original xt_LOG output.
This is an example output:
IN=wlan0 OUT= ARP HTYPE=1 PTYPE=0x0800 OPCODE=2 MACSRC=00:ab:12:34:55:63 IPSRC=192.168.10.1 MACDST=80:09:12:70:4f:50 IPDST=192.168.10.150
This patch enables packet logging from ARP chains, eg.
nft add rule arp filter input log prefix "input: "
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
net/ipv4/netfilter/Kconfig | 5 ++
net/ipv4/netfilter/Makefile | 1 +
net/ipv4/netfilter/nf_log_arp.c | 149 +++++++++++++++++++++++++++++++++++++++
3 files changed, 155 insertions(+)
create mode 100644 net/ipv4/netfilter/nf_log_arp.c
diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig
index 0c98029..12e6057 100644
--- a/net/ipv4/netfilter/Kconfig
+++ b/net/ipv4/netfilter/Kconfig
@@ -159,6 +159,11 @@ config IP_NF_TARGET_SYNPROXY
To compile it as a module, choose M here. If unsure, say N.
+config NF_LOG_ARP
+ tristate "ARP packet logging"
+ default m if NETFILTER_ADVANCED=n
+ select NF_LOG_INET
+
config NF_LOG_IPV4
tristate "IPv4 packet logging"
default m if NETFILTER_ADVANCED=n
diff --git a/net/ipv4/netfilter/Makefile b/net/ipv4/netfilter/Makefile
index 730e0c1..245db9d 100644
--- a/net/ipv4/netfilter/Makefile
+++ b/net/ipv4/netfilter/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_NF_NAT_IPV4) += nf_nat_ipv4.o
obj-$(CONFIG_NF_DEFRAG_IPV4) += nf_defrag_ipv4.o
# logging
+obj-$(CONFIG_NF_LOG_ARP) += nf_log_arp.o
obj-$(CONFIG_NF_LOG_IPV4) += nf_log_ipv4.o
# NAT helpers (nf_conntrack)
diff --git a/net/ipv4/netfilter/nf_log_arp.c b/net/ipv4/netfilter/nf_log_arp.c
new file mode 100644
index 0000000..ccfc78d
--- /dev/null
+++ b/net/ipv4/netfilter/nf_log_arp.c
@@ -0,0 +1,149 @@
+/*
+ * (C) 2014 by Pablo Neira Ayuso <pablo@...filter.org>
+ *
+ * Based on code from ebt_log from:
+ *
+ * Bart De Schuymer <bdschuym@...dora.be>
+ * Harald Welte <laforge@...filter.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/skbuff.h>
+#include <linux/if_arp.h>
+#include <linux/ip.h>
+#include <net/route.h>
+
+#include <linux/netfilter.h>
+#include <linux/netfilter/xt_LOG.h>
+#include <net/netfilter/nf_log.h>
+
+static struct nf_loginfo default_loginfo = {
+ .type = NF_LOG_TYPE_LOG,
+ .u = {
+ .log = {
+ .level = 5,
+ .logflags = NF_LOG_MASK,
+ },
+ },
+};
+
+struct arppayload {
+ unsigned char mac_src[ETH_ALEN];
+ unsigned char ip_src[4];
+ unsigned char mac_dst[ETH_ALEN];
+ unsigned char ip_dst[4];
+};
+
+static void dump_arp_packet(struct nf_log_buf *m,
+ const struct nf_loginfo *info,
+ const struct sk_buff *skb, unsigned int nhoff)
+{
+ const struct arphdr *ah;
+ struct arphdr _arph;
+ const struct arppayload *ap;
+ struct arppayload _arpp;
+
+ ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph);
+ if (ah == NULL) {
+ nf_log_buf_add(m, "TRUNCATED");
+ return;
+ }
+ nf_log_buf_add(m, "ARP HTYPE=%d PTYPE=0x%04x OPCODE=%d",
+ ntohs(ah->ar_hrd), ntohs(ah->ar_pro), ntohs(ah->ar_op));
+
+ /* If it's for Ethernet and the lengths are OK, then log the ARP
+ * payload.
+ */
+ if (ah->ar_hrd != htons(1) ||
+ ah->ar_hln != ETH_ALEN ||
+ ah->ar_pln != sizeof(__be32))
+ return;
+
+ ap = skb_header_pointer(skb, sizeof(_arph), sizeof(_arpp), &_arpp);
+ if (ap == NULL) {
+ nf_log_buf_add(m, " INCOMPLETE [%Zu bytes]",
+ skb->len - sizeof(_arph));
+ return;
+ }
+ nf_log_buf_add(m, " MACSRC=%pM IPSRC=%pI4 MACDST=%pM IPDST=%pI4",
+ ap->mac_src, ap->ip_src, ap->mac_dst, ap->ip_dst);
+}
+
+void nf_log_arp_packet(struct net *net, 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)
+{
+ struct nf_log_buf *m;
+
+ /* FIXME: Disabled from containers until syslog ns is supported */
+ if (!net_eq(net, &init_net))
+ return;
+
+ m = nf_log_buf_open();
+
+ if (!loginfo)
+ loginfo = &default_loginfo;
+
+ nf_log_dump_packet_common(m, pf, hooknum, skb, in, out, loginfo,
+ prefix);
+ dump_arp_packet(m, loginfo, skb, 0);
+
+ nf_log_buf_close(m);
+}
+
+static struct nf_logger nf_arp_logger __read_mostly = {
+ .name = "nf_log_arp",
+ .type = NF_LOG_TYPE_LOG,
+ .logfn = nf_log_arp_packet,
+ .me = THIS_MODULE,
+};
+
+static int __net_init nf_log_arp_net_init(struct net *net)
+{
+ nf_log_set(net, NFPROTO_ARP, &nf_arp_logger);
+ return 0;
+}
+
+static void __net_exit nf_log_arp_net_exit(struct net *net)
+{
+ nf_log_unset(net, &nf_arp_logger);
+}
+
+static struct pernet_operations nf_log_arp_net_ops = {
+ .init = nf_log_arp_net_init,
+ .exit = nf_log_arp_net_exit,
+};
+
+static int __init nf_log_arp_init(void)
+{
+ int ret;
+
+ ret = register_pernet_subsys(&nf_log_arp_net_ops);
+ if (ret < 0)
+ return ret;
+
+ nf_log_register(NFPROTO_ARP, &nf_arp_logger);
+ return 0;
+}
+
+static void __exit nf_log_arp_exit(void)
+{
+ unregister_pernet_subsys(&nf_log_arp_net_ops);
+ nf_log_unregister(&nf_arp_logger);
+}
+
+module_init(nf_log_arp_init);
+module_exit(nf_log_arp_exit);
+
+MODULE_AUTHOR("Pablo Neira Ayuso <pablo@...filter.org>");
+MODULE_DESCRIPTION("Netfilter ARP packet logging");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_NF_LOGGER(3, 0);
--
1.7.10.4
--
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