Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next

Pablo Neira Ayuso says:

====================
This batch contains one single patch with the l2tp match
for xtables, from James Chapman.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/netfilter/Kbuild

@@ -58,6 +58,7 @@ header-y += xt_helper.h
 header-y += xt_ipcomp.h
 header-y += xt_iprange.h
 header-y += xt_ipvs.h
+header-y += xt_l2tp.h
 header-y += xt_length.h
 header-y += xt_limit.h
 header-y += xt_mac.h

include/uapi/linux/netfilter/xt_l2tp.h

@@ -0,0 +1,27 @@
+#ifndef _LINUX_NETFILTER_XT_L2TP_H
+#define _LINUX_NETFILTER_XT_L2TP_H
+
+#include <linux/types.h>
+
+enum xt_l2tp_type {
+	XT_L2TP_TYPE_CONTROL,
+	XT_L2TP_TYPE_DATA,
+};
+
+/* L2TP matching stuff */
+struct xt_l2tp_info {
+	__u32 tid;			/* tunnel id */
+	__u32 sid;			/* session id */
+	__u8 version;			/* L2TP protocol version */
+	__u8 type;			/* L2TP packet type */
+	__u8 flags;			/* which fields to match */
+};
+
+enum {
+	XT_L2TP_TID	= (1 << 0),	/* match L2TP tunnel id */
+	XT_L2TP_SID	= (1 << 1),	/* match L2TP session id */
+	XT_L2TP_VERSION	= (1 << 2),	/* match L2TP protocol version */
+	XT_L2TP_TYPE	= (1 << 3),	/* match L2TP packet type */
+};
+
+#endif /* _LINUX_NETFILTER_XT_L2TP_H */

net/netfilter/Kconfig

@@ -1139,6 +1139,16 @@ config NETFILTER_XT_MATCH_IPVS
 
 	  If unsure, say N.
 
+config NETFILTER_XT_MATCH_L2TP
+	tristate '"l2tp" match support'
+	depends on NETFILTER_ADVANCED
+	default L2TP
+	---help---
+	This option adds an "L2TP" match, which allows you to match against
+	L2TP protocol header fields.
+
+	To compile it as a module, choose M here. If unsure, say N.
+
 config NETFILTER_XT_MATCH_LENGTH
 	tristate '"length" match support'
 	depends on NETFILTER_ADVANCED

net/netfilter/Makefile

@@ -138,6 +138,7 @@ obj-$(CONFIG_NETFILTER_XT_MATCH_HL) += xt_hl.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_IPCOMP) += xt_ipcomp.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_IPRANGE) += xt_iprange.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_IPVS) += xt_ipvs.o
+obj-$(CONFIG_NETFILTER_XT_MATCH_L2TP) += xt_l2tp.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_LENGTH) += xt_length.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_LIMIT) += xt_limit.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_MAC) += xt_mac.o

net/netfilter/xt_l2tp.c

@@ -0,0 +1,354 @@
+/* Kernel module to match L2TP header parameters. */
+
+/* (C) 2013      James Chapman <jchapman@katalix.com>
+ *
+ * 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.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/if_ether.h>
+#include <net/ip.h>
+#include <linux/ipv6.h>
+#include <net/ipv6.h>
+#include <net/udp.h>
+#include <linux/l2tp.h>
+
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter_ipv6.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv6/ip6_tables.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_tcpudp.h>
+#include <linux/netfilter/xt_l2tp.h>
+
+/* L2TP header masks */
+#define L2TP_HDR_T_BIT	0x8000
+#define L2TP_HDR_L_BIT	0x4000
+#define L2TP_HDR_VER	0x000f
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
+MODULE_DESCRIPTION("Xtables: L2TP header match");
+MODULE_ALIAS("ipt_l2tp");
+MODULE_ALIAS("ip6t_l2tp");
+
+/* The L2TP fields that can be matched */
+struct l2tp_data {
+	u32 tid;
+	u32 sid;
+	u8 type;
+	u8 version;
+};
+
+union l2tp_val {
+	__be16 val16[2];
+	__be32 val32;
+};
+
+static bool l2tp_match(const struct xt_l2tp_info *info, struct l2tp_data *data)
+{
+	if ((info->flags & XT_L2TP_TYPE) && (info->type != data->type))
+		return false;
+
+	if ((info->flags & XT_L2TP_VERSION) && (info->version != data->version))
+		return false;
+
+	/* Check tid only for L2TPv3 control or any L2TPv2 packets */
+	if ((info->flags & XT_L2TP_TID) &&
+	    ((data->type == XT_L2TP_TYPE_CONTROL) || (data->version == 2)) &&
+	    (info->tid != data->tid))
+		return false;
+
+	/* Check sid only for L2TP data packets */
+	if ((info->flags & XT_L2TP_SID) && (data->type == XT_L2TP_TYPE_DATA) &&
+	    (info->sid != data->sid))
+		return false;
+
+	return true;
+}
+
+/* Parse L2TP header fields when UDP encapsulation is used. Handles
+ * L2TPv2 and L2TPv3. Note the L2TPv3 control and data packets have a
+ * different format. See
+ * RFC2661, Section 3.1, L2TPv2 Header Format
+ * RFC3931, Section 3.2.1, L2TPv3 Control Message Header
+ * RFC3931, Section 3.2.2, L2TPv3 Data Message Header
+ * RFC3931, Section 4.1.2.1, L2TPv3 Session Header over UDP
+ */
+static bool l2tp_udp_mt(const struct sk_buff *skb, struct xt_action_param *par, u16 thoff)
+{
+	const struct xt_l2tp_info *info = par->matchinfo;
+	int uhlen = sizeof(struct udphdr);
+	int offs = thoff + uhlen;
+	union l2tp_val *lh;
+	union l2tp_val lhbuf;
+	u16 flags;
+	struct l2tp_data data = { 0, };
+
+	if (par->fragoff != 0)
+		return false;
+
+	/* Extract L2TP header fields. The flags in the first 16 bits
+	 * tell us where the other fields are.
+	 */
+	lh = skb_header_pointer(skb, offs, 2, &lhbuf);
+	if (lh == NULL)
+		return false;
+
+	flags = ntohs(lh->val16[0]);
+	if (flags & L2TP_HDR_T_BIT)
+		data.type = XT_L2TP_TYPE_CONTROL;
+	else
+		data.type = XT_L2TP_TYPE_DATA;
+	data.version = (u8) flags & L2TP_HDR_VER;
+
+	/* Now extract the L2TP tid/sid. These are in different places
+	 * for L2TPv2 (rfc2661) and L2TPv3 (rfc3931). For L2TPv2, we
+	 * must also check to see if the length field is present,
+	 * since this affects the offsets into the packet of the
+	 * tid/sid fields.
+	 */
+	if (data.version == 3) {
+		lh = skb_header_pointer(skb, offs + 4, 4, &lhbuf);
+		if (lh == NULL)
+			return false;
+		if (data.type == XT_L2TP_TYPE_CONTROL)
+			data.tid = ntohl(lh->val32);
+		else
+			data.sid = ntohl(lh->val32);
+	} else if (data.version == 2) {
+		if (flags & L2TP_HDR_L_BIT)
+			offs += 2;
+		lh = skb_header_pointer(skb, offs + 2, 4, &lhbuf);
+		if (lh == NULL)
+			return false;
+		data.tid = (u32) ntohs(lh->val16[0]);
+		data.sid = (u32) ntohs(lh->val16[1]);
+	} else
+		return false;
+
+	return l2tp_match(info, &data);
+}
+
+/* Parse L2TP header fields for IP encapsulation (no UDP header).
+ * L2TPv3 data packets have a different form with IP encap. See
+ * RC3931, Section 4.1.1.1, L2TPv3 Session Header over IP.
+ * RC3931, Section 4.1.1.2, L2TPv3 Control and Data Traffic over IP.
+ */
+static bool l2tp_ip_mt(const struct sk_buff *skb, struct xt_action_param *par, u16 thoff)
+{
+	const struct xt_l2tp_info *info = par->matchinfo;
+	union l2tp_val *lh;
+	union l2tp_val lhbuf;
+	struct l2tp_data data = { 0, };
+
+	/* For IP encap, the L2TP sid is the first 32-bits. */
+	lh = skb_header_pointer(skb, thoff, sizeof(lhbuf), &lhbuf);
+	if (lh == NULL)
+		return false;
+	if (lh->val32 == 0) {
+		/* Must be a control packet. The L2TP tid is further
+		 * into the packet.
+		 */
+		data.type = XT_L2TP_TYPE_CONTROL;
+		lh = skb_header_pointer(skb, thoff + 8, sizeof(lhbuf),
+					&lhbuf);
+		if (lh == NULL)
+			return false;
+		data.tid = ntohl(lh->val32);
+	} else {
+		data.sid = ntohl(lh->val32);
+		data.type = XT_L2TP_TYPE_DATA;
+	}
+
+	data.version = 3;
+
+	return l2tp_match(info, &data);
+}
+
+static bool l2tp_mt4(const struct sk_buff *skb, struct xt_action_param *par)
+{
+	struct iphdr *iph = ip_hdr(skb);
+	u8 ipproto = iph->protocol;
+
+	/* l2tp_mt_check4 already restricts the transport protocol */
+	switch (ipproto) {
+	case IPPROTO_UDP:
+		return l2tp_udp_mt(skb, par, par->thoff);
+	case IPPROTO_L2TP:
+		return l2tp_ip_mt(skb, par, par->thoff);
+	}
+
+	return false;
+}
+
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+static bool l2tp_mt6(const struct sk_buff *skb, struct xt_action_param *par)
+{
+	unsigned int thoff = 0;
+	unsigned short fragoff = 0;
+	int ipproto;
+
+	ipproto = ipv6_find_hdr(skb, &thoff, -1, &fragoff, NULL);
+	if (fragoff != 0)
+		return false;
+
+	/* l2tp_mt_check6 already restricts the transport protocol */
+	switch (ipproto) {
+	case IPPROTO_UDP:
+		return l2tp_udp_mt(skb, par, thoff);
+	case IPPROTO_L2TP:
+		return l2tp_ip_mt(skb, par, thoff);
+	}
+
+	return false;
+}
+#endif
+
+static int l2tp_mt_check(const struct xt_mtchk_param *par)
+{
+	const struct xt_l2tp_info *info = par->matchinfo;
+
+	/* Check for invalid flags */
+	if (info->flags & ~(XT_L2TP_TID | XT_L2TP_SID | XT_L2TP_VERSION |
+			    XT_L2TP_TYPE)) {
+		pr_info("unknown flags: %x\n", info->flags);
+		return -EINVAL;
+	}
+
+	/* At least one of tid, sid or type=control must be specified */
+	if ((!(info->flags & XT_L2TP_TID)) &&
+	    (!(info->flags & XT_L2TP_SID)) &&
+	    ((!(info->flags & XT_L2TP_TYPE)) ||
+	     (info->type != XT_L2TP_TYPE_CONTROL))) {
+		pr_info("invalid flags combination: %x\n", info->flags);
+		return -EINVAL;
+	}
+
+	/* If version 2 is specified, check that incompatible params
+	 * are not supplied
+	 */
+	if (info->flags & XT_L2TP_VERSION) {
+		if ((info->version < 2) || (info->version > 3)) {
+			pr_info("wrong L2TP version: %u\n", info->version);
+			return -EINVAL;
+		}
+
+		if (info->version == 2) {
+			if ((info->flags & XT_L2TP_TID) &&
+			    (info->tid > 0xffff)) {
+				pr_info("v2 tid > 0xffff: %u\n", info->tid);
+				return -EINVAL;
+			}
+			if ((info->flags & XT_L2TP_SID) &&
+			    (info->sid > 0xffff)) {
+				pr_info("v2 sid > 0xffff: %u\n", info->sid);
+				return -EINVAL;
+			}
+		}
+	}
+
+	return 0;
+}
+
+static int l2tp_mt_check4(const struct xt_mtchk_param *par)
+{
+	const struct xt_l2tp_info *info = par->matchinfo;
+	const struct ipt_entry *e = par->entryinfo;
+	const struct ipt_ip *ip = &e->ip;
+	int ret;
+
+	ret = l2tp_mt_check(par);
+	if (ret != 0)
+		return ret;
+
+	if ((ip->proto != IPPROTO_UDP) &&
+	    (ip->proto != IPPROTO_L2TP)) {
+		pr_info("missing protocol rule (udp|l2tpip)\n");
+		return -EINVAL;
+	}
+
+	if ((ip->proto == IPPROTO_L2TP) &&
+	    (info->version == 2)) {
+		pr_info("v2 doesn't support IP mode\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+static int l2tp_mt_check6(const struct xt_mtchk_param *par)
+{
+	const struct xt_l2tp_info *info = par->matchinfo;
+	const struct ip6t_entry *e = par->entryinfo;
+	const struct ip6t_ip6 *ip = &e->ipv6;
+	int ret;
+
+	ret = l2tp_mt_check(par);
+	if (ret != 0)
+		return ret;
+
+	if ((ip->proto != IPPROTO_UDP) &&
+	    (ip->proto != IPPROTO_L2TP)) {
+		pr_info("missing protocol rule (udp|l2tpip)\n");
+		return -EINVAL;
+	}
+
+	if ((ip->proto == IPPROTO_L2TP) &&
+	    (info->version == 2)) {
+		pr_info("v2 doesn't support IP mode\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+#endif
+
+static struct xt_match l2tp_mt_reg[] __read_mostly = {
+	{
+		.name      = "l2tp",
+		.revision  = 0,
+		.family    = NFPROTO_IPV4,
+		.match     = l2tp_mt4,
+		.matchsize = XT_ALIGN(sizeof(struct xt_l2tp_info)),
+		.checkentry = l2tp_mt_check4,
+		.hooks     = ((1 << NF_INET_PRE_ROUTING) |
+			      (1 << NF_INET_LOCAL_IN) |
+			      (1 << NF_INET_LOCAL_OUT) |
+			      (1 << NF_INET_FORWARD)),
+		.me        = THIS_MODULE,
+	},
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+	{
+		.name      = "l2tp",
+		.revision  = 0,
+		.family    = NFPROTO_IPV6,
+		.match     = l2tp_mt6,
+		.matchsize = XT_ALIGN(sizeof(struct xt_l2tp_info)),
+		.checkentry = l2tp_mt_check6,
+		.hooks     = ((1 << NF_INET_PRE_ROUTING) |
+			      (1 << NF_INET_LOCAL_IN) |
+			      (1 << NF_INET_LOCAL_OUT) |
+			      (1 << NF_INET_FORWARD)),
+		.me        = THIS_MODULE,
+	},
+#endif
+};
+
+static int __init l2tp_mt_init(void)
+{
+	return xt_register_matches(&l2tp_mt_reg[0], ARRAY_SIZE(l2tp_mt_reg));
+}
+
+static void __exit l2tp_mt_exit(void)
+{
+	xt_unregister_matches(&l2tp_mt_reg[0], ARRAY_SIZE(l2tp_mt_reg));
+}
+
+module_init(l2tp_mt_init);
+module_exit(l2tp_mt_exit);