conntrackd: add cthelper infrastructure (+ example FTP helper)

This patch adds the user-space helper infrastructure. It also
contains the implementation of the FTP helper in user-space.

There's one example file that you can use to configure conntrackd
as user-space connection tracking helper under:

 doc/helper/conntrackd.conf

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

3 files changed, 155 insertions, 1 deletions

diff --git a/include/linux/netfilter/Makefile.am b/include/linux/netfilter/Makefile.am
index 84315e3..6574060 100644
--- a/include/linux/netfilter/Makefile.am
+++ b/include/linux/netfilter/Makefile.am
@@ -1 +1 @@
-noinst_HEADERS = nfnetlink.h nfnetlink_cttimeout.h
+noinst_HEADERS = nfnetlink.h nfnetlink_cttimeout.h nfnetlink_queue.h nfnetlink_cthelper.h
diff --git a/include/linux/netfilter/nfnetlink_cthelper.h b/include/linux/netfilter/nfnetlink_cthelper.h
new file mode 100644
index 0000000..33659f6
--- /dev/null
+++ b/include/linux/netfilter/nfnetlink_cthelper.h
@@ -0,0 +1,55 @@
+#ifndef _NFNL_CTHELPER_H_
+#define _NFNL_CTHELPER_H_
+
+#define NFCT_HELPER_STATUS_DISABLED	0
+#define NFCT_HELPER_STATUS_ENABLED	1
+
+enum nfnl_acct_msg_types {
+	NFNL_MSG_CTHELPER_NEW,
+	NFNL_MSG_CTHELPER_GET,
+	NFNL_MSG_CTHELPER_DEL,
+	NFNL_MSG_CTHELPER_MAX
+};
+
+enum nfnl_cthelper_type {
+	NFCTH_UNSPEC,
+	NFCTH_NAME,
+	NFCTH_TUPLE,
+	NFCTH_QUEUE_NUM,
+	NFCTH_POLICY,
+	NFCTH_PRIV_DATA_LEN,
+	NFCTH_STATUS,
+	__NFCTH_MAX
+};
+#define NFCTH_MAX (__NFCTH_MAX - 1)
+
+enum nfnl_cthelper_policy_type {
+	NFCTH_POLICY_SET_UNSPEC,
+	NFCTH_POLICY_SET_NUM,
+	NFCTH_POLICY_SET,
+	NFCTH_POLICY_SET1	= NFCTH_POLICY_SET,
+	NFCTH_POLICY_SET2,
+	NFCTH_POLICY_SET3,
+	NFCTH_POLICY_SET4,
+	__NFCTH_POLICY_SET_MAX
+};
+#define NFCTH_POLICY_SET_MAX (__NFCTH_POLICY_SET_MAX - 1)
+
+enum nfnl_cthelper_pol_type {
+	NFCTH_POLICY_UNSPEC,
+	NFCTH_POLICY_NAME,
+	NFCTH_POLICY_EXPECT_MAX,
+	NFCTH_POLICY_EXPECT_TIMEOUT,
+	__NFCTH_POLICY_MAX
+};
+#define NFCTH_POLICY_MAX (__NFCTH_POLICY_MAX - 1)
+
+enum nfnl_cthelper_tuple_type {
+	NFCTH_TUPLE_UNSPEC,
+	NFCTH_TUPLE_L3PROTONUM,
+	NFCTH_TUPLE_L4PROTONUM,
+	__NFCTH_TUPLE_MAX,
+};
+#define NFCTH_TUPLE_MAX (__NFCTH_TUPLE_MAX - 1)
+
+#endif /* _NFNL_CTHELPER_H */
diff --git a/include/linux/netfilter/nfnetlink_queue.h b/include/linux/netfilter/nfnetlink_queue.h
new file mode 100644
index 0000000..e0d8fd8
--- /dev/null
+++ b/include/linux/netfilter/nfnetlink_queue.h
@@ -0,0 +1,99 @@
+#ifndef _NFNETLINK_QUEUE_H
+#define _NFNETLINK_QUEUE_H
+
+#include <linux/types.h>
+#include <linux/netfilter/nfnetlink.h>
+
+enum nfqnl_msg_types {
+	NFQNL_MSG_PACKET,		/* packet from kernel to userspace */
+	NFQNL_MSG_VERDICT,		/* verdict from userspace to kernel */
+	NFQNL_MSG_CONFIG,		/* connect to a particular queue */
+	NFQNL_MSG_VERDICT_BATCH,	/* batchv from userspace to kernel */
+
+	NFQNL_MSG_MAX
+};
+
+struct nfqnl_msg_packet_hdr {
+	__be32		packet_id;	/* unique ID of packet in queue */
+	__be16		hw_protocol;	/* hw protocol (network order) */
+	__u8	hook;		/* netfilter hook */
+} __attribute__ ((packed));
+
+struct nfqnl_msg_packet_hw {
+	__be16		hw_addrlen;
+	__u16	_pad;
+	__u8	hw_addr[8];
+};
+
+struct nfqnl_msg_packet_timestamp {
+	__aligned_be64	sec;
+	__aligned_be64	usec;
+};
+
+enum nfqnl_attr_type {
+	NFQA_UNSPEC,
+	NFQA_PACKET_HDR,
+	NFQA_VERDICT_HDR,		/* nfqnl_msg_verdict_hrd */
+	NFQA_MARK,			/* __u32 nfmark */
+	NFQA_TIMESTAMP,			/* nfqnl_msg_packet_timestamp */
+	NFQA_IFINDEX_INDEV,		/* __u32 ifindex */
+	NFQA_IFINDEX_OUTDEV,		/* __u32 ifindex */
+	NFQA_IFINDEX_PHYSINDEV,		/* __u32 ifindex */
+	NFQA_IFINDEX_PHYSOUTDEV,	/* __u32 ifindex */
+	NFQA_HWADDR,			/* nfqnl_msg_packet_hw */
+	NFQA_PAYLOAD,			/* opaque data payload */
+	NFQA_CT,			/* nf_conntrack_netlink.h */
+	NFQA_CT_INFO,			/* enum ip_conntrack_info */
+
+	__NFQA_MAX
+};
+#define NFQA_MAX (__NFQA_MAX - 1)
+
+struct nfqnl_msg_verdict_hdr {
+	__be32 verdict;
+	__be32 id;
+};
+
+
+enum nfqnl_msg_config_cmds {
+	NFQNL_CFG_CMD_NONE,
+	NFQNL_CFG_CMD_BIND,
+	NFQNL_CFG_CMD_UNBIND,
+	NFQNL_CFG_CMD_PF_BIND,
+	NFQNL_CFG_CMD_PF_UNBIND,
+};
+
+struct nfqnl_msg_config_cmd {
+	__u8	command;	/* nfqnl_msg_config_cmds */
+	__u8	_pad;
+	__be16		pf;		/* AF_xxx for PF_[UN]BIND */
+};
+
+enum nfqnl_config_mode {
+	NFQNL_COPY_NONE,
+	NFQNL_COPY_META,
+	NFQNL_COPY_PACKET,
+};
+
+struct nfqnl_msg_config_params {
+	__be32		copy_range;
+	__u8	copy_mode;	/* enum nfqnl_config_mode */
+} __attribute__ ((packed));
+
+
+enum nfqnl_attr_config {
+	NFQA_CFG_UNSPEC,
+	NFQA_CFG_CMD,			/* nfqnl_msg_config_cmd */
+	NFQA_CFG_PARAMS,		/* nfqnl_msg_config_params */
+	NFQA_CFG_QUEUE_MAXLEN,		/* __u32 */
+	NFQA_CFG_MASK,			/* identify which flags to change */
+	NFQA_CFG_FLAGS,			/* value of these flags (__u32) */
+	__NFQA_CFG_MAX
+};
+#define NFQA_CFG_MAX (__NFQA_CFG_MAX-1)
+
+/* Flags for NFQA_CFG_FLAGS */
+#define NFQA_CFG_F_FAIL_OPEN			(1 << 0)
+#define NFQA_CFG_F_CONNTRACK			(1 << 1)
+
+#endif /* _NFNETLINK_QUEUE_H */