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netfilter: refactor NAT's redirect IPv4 code

PATCH In review Arturo Borrero Gonzalez 2 participants 8 messages Oct 14, 2014 – Oct 16, 2014

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Arturo Borrero Gonzalez

author
#0 lore raw

PATCH 1/3 netfilter: refactor NAT's redirect IPv4 code

The xt_REDIRECT can be seen as a NAT flavour (like masquerade).

This patch refactors the IPv4 code so it can be usable both from xt and nf_tables.

A similar patch follows-up to handle IPv6.

Signed-off-by Arturo Borrero Gonzalez <[email protected]>
---
 include/net/netfilter/ipv4/nf_nat_redirect.h |    9 +++
 net/ipv4/netfilter/Kconfig                   |    6 ++
 net/ipv4/netfilter/Makefile                  |    1 
 net/ipv4/netfilter/nf_nat_redirect_ipv4.c    |   80 ++++++++++++++++++++++++++
 net/netfilter/Kconfig                        |    1 
 net/netfilter/xt_REDIRECT.c                  |   44 +-------------
 6 files changed, 99 insertions(+), 42 deletions(-)
 create mode 100644 include/net/netfilter/ipv4/nf_nat_redirect.h
 create mode 100644 net/ipv4/netfilter/nf_nat_redirect_ipv4.c
include/net/netfilter/ipv4/nf_nat_redirect.h new file +9 -0
new file mode 100644
index 0000000..19e1df3
@@ -0,0 +1,9 @@
+#ifndef _NF_NAT_REDIRECT_IPV4_H_
+#define _NF_NAT_REDIRECT_IPV4_H_
+
+unsigned int
+nf_nat_redirect_ipv4(struct sk_buff *skb,
+		     const struct nf_nat_ipv4_multi_range_compat *mr,
+		     unsigned int hooknum);
+
+#endif /* _NF_NAT_REDIRECT_IPV4_H_ */
net/ipv4/netfilter/Kconfig +6 -0
index 4c019d5..a300e2c 100644
@@ -104,6 +104,12 @@ config NF_NAT_MASQUERADE_IPV4
 	  This is the kernel functionality to provide NAT in the masquerade
 	  flavour (automatic source address selection).
 
+config NF_NAT_REDIRECT_IPV4
+	tristate "IPv4 redirect support"
+	help
+	  This is the kernel functionality to provide NAT in the redirect
+	  flavour (redirect packets to local machine).
+
 config NFT_MASQ_IPV4
 	tristate "IPv4 masquerading support for nf_tables"
 	depends on NF_TABLES_IPV4
net/ipv4/netfilter/Makefile +1 -0
index f4cef5a..34e436c 100644
@@ -31,6 +31,7 @@ obj-$(CONFIG_NF_NAT_H323) += nf_nat_h323.o
 obj-$(CONFIG_NF_NAT_PPTP) += nf_nat_pptp.o
 obj-$(CONFIG_NF_NAT_SNMP_BASIC) += nf_nat_snmp_basic.o
 obj-$(CONFIG_NF_NAT_MASQUERADE_IPV4) += nf_nat_masquerade_ipv4.o
+obj-$(CONFIG_NF_NAT_REDIRECT_IPV4) += nf_nat_redirect_ipv4.o
 
 # NAT protocols (nf_nat)
 obj-$(CONFIG_NF_NAT_PROTO_GRE) += nf_nat_proto_gre.o
net/ipv4/netfilter/nf_nat_redirect_ipv4.c new file +80 -0

80 lines not on this page · raw message

net/netfilter/Kconfig +1 -0
index ae5096a..bc0726d 100644
@@ -835,6 +835,7 @@ config NETFILTER_XT_TARGET_RATEEST
 config NETFILTER_XT_TARGET_REDIRECT
 	tristate "REDIRECT target support"
 	depends on NF_NAT
+	depends on NF_NAT_REDIRECT_IPV4
 	---help---
 	REDIRECT is a special case of NAT: all incoming connections are
 	mapped onto the incoming interface's address, causing the packets to
net/netfilter/xt_REDIRECT.c +2 -42

56 lines not on this page · raw message

author
#1 lore raw

PATCH 2/3 netfilter: refactor NAT's redirect IPv6 code

The xt_REDIRECT can be seen as a NAT flavour (like masquerade).

This patch refactors the IPv6 code so it can be usable both from xt and nf_tables.

Signed-off-by Arturo Borrero Gonzalez <[email protected]>
---
 include/net/netfilter/ipv6/nf_nat_redirect.h |    9 +++
 net/ipv6/netfilter/Kconfig                   |    6 ++
 net/ipv6/netfilter/Makefile                  |    1 
 net/ipv6/netfilter/nf_nat_redirect_ipv6.c    |   75 ++++++++++++++++++++++++++
 net/netfilter/Kconfig                        |    1 
 net/netfilter/xt_REDIRECT.c                  |   40 +-------------
 6 files changed, 94 insertions(+), 38 deletions(-)
 create mode 100644 include/net/netfilter/ipv6/nf_nat_redirect.h
 create mode 100644 net/ipv6/netfilter/nf_nat_redirect_ipv6.c
include/net/netfilter/ipv6/nf_nat_redirect.h new file +9 -0
new file mode 100644
index 0000000..aab7617
@@ -0,0 +1,9 @@
+#ifndef _NF_NAT_REDIRECT_IPV6_H_
+#define _NF_NAT_REDIRECT_IPV6_H_
+
+unsigned int
+nf_nat_redirect_ipv6(struct sk_buff *skb, const struct nf_nat_range *range,
+		     unsigned int hooknum);
+
+#endif /* _NF_NAT_REDIRECT_IPV6_H_ */
+
net/ipv6/netfilter/Kconfig +6 -0
index 6af874f..462eebb 100644
@@ -82,6 +82,12 @@ config NF_NAT_MASQUERADE_IPV6
 	  This is the kernel functionality to provide NAT in the masquerade
 	  flavour (automatic source address selection) for IPv6.
 
+config NF_NAT_REDIRECT_IPV6
+	tristate "IPv6 redirect support"
+	help
+	  This is the kernel functionality to provide NAT in the redirect
+	  flavour (redirect packet to local machine) for IPv6.
+
 config NFT_MASQ_IPV6
 	tristate "IPv6 masquerade support for nf_tables"
 	depends on NF_TABLES_IPV6
net/ipv6/netfilter/Makefile +1 -0
index fbb25f0..6c2baab 100644
@@ -19,6 +19,7 @@ obj-$(CONFIG_NF_CONNTRACK_IPV6) += nf_conntrack_ipv6.o
 nf_nat_ipv6-y		:= nf_nat_l3proto_ipv6.o nf_nat_proto_icmpv6.o
 obj-$(CONFIG_NF_NAT_IPV6) += nf_nat_ipv6.o
 obj-$(CONFIG_NF_NAT_MASQUERADE_IPV6) += nf_nat_masquerade_ipv6.o
+obj-$(CONFIG_NF_NAT_REDIRECT_IPV6) += nf_nat_redirect_ipv6.o
 
 # defrag
 nf_defrag_ipv6-y := nf_defrag_ipv6_hooks.o nf_conntrack_reasm.o
net/ipv6/netfilter/nf_nat_redirect_ipv6.c new file +75 -0

75 lines not on this page · raw message

net/netfilter/Kconfig +1 -0
index bc0726d..1d0131c 100644
@@ -836,6 +836,7 @@ config NETFILTER_XT_TARGET_REDIRECT
 	tristate "REDIRECT target support"
 	depends on NF_NAT
 	depends on NF_NAT_REDIRECT_IPV4
+	depends on NF_NAT_REDIRECT_IPV6
 	---help---
 	REDIRECT is a special case of NAT: all incoming connections are
 	mapped onto the incoming interface's address, causing the packets to
net/netfilter/xt_REDIRECT.c +2 -38
index b4ffac5..b6ec67e 100644
@@ -27,48 +27,12 @@
 #include <net/protocol.h>
 #include <net/netfilter/nf_nat.h>
 #include <net/netfilter/ipv4/nf_nat_redirect.h>
-
-static const struct in6_addr loopback_addr = IN6ADDR_LOOPBACK_INIT;
+#include <net/netfilter/ipv6/nf_nat_redirect.h>
 
 static unsigned int
 redirect_tg6(struct sk_buff *skb, const struct xt_action_param *par)
 {
-	const struct nf_nat_range *range = par->targinfo;
-	struct nf_nat_range newrange;
-	struct in6_addr newdst;
-	enum ip_conntrack_info ctinfo;
-	struct nf_conn *ct;
-
-	ct = nf_ct_get(skb, &ctinfo);
-	if (par->hooknum == NF_INET_LOCAL_OUT)
-		newdst = loopback_addr;
-	else {
-		struct inet6_dev *idev;
-		struct inet6_ifaddr *ifa;
-		bool addr = false;
-
-		rcu_read_lock();
-		idev = __in6_dev_get(skb->dev);
-		if (idev != NULL) {
-			list_for_each_entry(ifa, &idev->addr_list, if_list) {
-				newdst = ifa->addr;
-				addr = true;
-				break;
-			}
-		}
-		rcu_read_unlock();
-
-		if (!addr)
-			return NF_DROP;
-	}
-
-	newrange.flags		= range->flags | NF_NAT_RANGE_MAP_IPS;
-	newrange.min_addr.in6	= newdst;
-	newrange.max_addr.in6	= newdst;
-	newrange.min_proto	= range->min_proto;
-	newrange.max_proto	= range->max_proto;
-
-	return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST);
+	return nf_nat_redirect_ipv6(skb, par->targinfo, par->hooknum);
 }
 
 static int redirect_tg6_checkentry(const struct xt_tgchk_param *par)
author
#2 lore raw

PATCH 3/3 netfilter: nf_tables: add new expression nft_redir

In reply to Arturo Borrero Gonzalez

This new expression provides NAT in the redirect flavour, which is to redirect packets to local machine.

Signed-off-by Arturo Borrero Gonzalez <[email protected]>
---
 include/net/netfilter/nft_redir.h        |   18 ++++++
 include/uapi/linux/netfilter/nf_tables.h |   16 +++++
 net/ipv4/netfilter/Kconfig               |    9 +++
 net/ipv4/netfilter/Makefile              |    1 
 net/ipv4/netfilter/nft_redir_ipv4.c      |   76 +++++++++++++++++++++++++
 net/ipv6/netfilter/Kconfig               |    9 +++
 net/ipv6/netfilter/Makefile              |    1 
 net/netfilter/Kconfig                    |    9 +++
 net/netfilter/Makefile                   |    1 
 net/netfilter/nft_redir.c                |   93 ++++++++++++++++++++++++++++++
 10 files changed, 233 insertions(+)
 create mode 100644 include/net/netfilter/nft_redir.h
 create mode 100644 net/ipv4/netfilter/nft_redir_ipv4.c
 create mode 100644 net/netfilter/nft_redir.c
include/net/netfilter/nft_redir.h new file +18 -0
new file mode 100644
index 0000000..b6695da
@@ -0,0 +1,18 @@
+#ifndef _NFT_REDIR_H_
+#define _NFT_REDIR_H_
+
+struct nft_redir {
+	enum nft_registers	sreg_proto_min:8;
+	enum nft_registers	sreg_proto_max:8;
+	u32			flags;
+};
+
+extern const struct nla_policy nft_redir_policy[];
+
+int nft_redir_init(const struct nft_ctx *ctx,
+		   const struct nft_expr *expr,
+		   const struct nlattr * const tb[]);
+
+int nft_redir_dump(struct sk_buff *skb, const struct nft_expr *expr);
+
+#endif /* _NFT_REDIR_H_ */
include/uapi/linux/netfilter/nf_tables.h +16 -0
index c26df67..8a96a36 100644
@@ -849,4 +849,20 @@ enum nft_gen_attributes {
 };
 #define NFTA_GEN_MAX		(__NFTA_GEN_MAX - 1)
 
+/**
+ * enum nft_redir_attributes - nf_tables redirect expression netlink attributes
+ *
+ * @NFTA_REDIR_REG_PROTO_MIN: source register of proto range start (NLA_U32: nft_registers)
+ * @NFTA_REDIR_REG_PROTO_MAX: source register of proto range end (NLA_U32: nft_registers)
+ * @NFTA_REDIR_FLAGS: NAT flags (see NF_NAT_RANGE_* in linux/netfilter/nf_nat.h) (NLA_U32)
+ */
+enum nft_redir_attributes {
+	NFTA_REDIR_UNSPEC,
+	NFTA_REDIR_REG_PROTO_MIN,
+	NFTA_REDIR_REG_PROTO_MAX,
+	NFTA_REDIR_FLAGS,
+	__NFTA_REDIR_MAX
+};
+#define NFTA_REDIR_MAX		(__NFTA_REDIR_MAX - 1)
+
 #endif /* _LINUX_NF_TABLES_H */
net/ipv4/netfilter/Kconfig +9 -0
index a300e2c..8358b2d 100644
@@ -119,6 +119,15 @@ config NFT_MASQ_IPV4
 	  This is the expression that provides IPv4 masquerading support for
 	  nf_tables.
 
+config NFT_REDIR_IPV4
+	tristate "IPv4 redirect support for nf_tables"
+	depends on NF_TABLES_IPV4
+	depends on NFT_REDIR
+	select NF_NAT_REDIRECT_IPV4
+	help
+	  This is the expression that provides IPv4 redirect support for
+	  nf_tables.
+
 config NF_NAT_SNMP_BASIC
 	tristate "Basic SNMP-ALG support"
 	depends on NF_CONNTRACK_SNMP
net/ipv4/netfilter/Makefile +1 -0
index 34e436c..902bcd1 100644
@@ -41,6 +41,7 @@ obj-$(CONFIG_NFT_CHAIN_ROUTE_IPV4) += nft_chain_route_ipv4.o
 obj-$(CONFIG_NFT_CHAIN_NAT_IPV4) += nft_chain_nat_ipv4.o
 obj-$(CONFIG_NFT_REJECT_IPV4) += nft_reject_ipv4.o
 obj-$(CONFIG_NFT_MASQ_IPV4) += nft_masq_ipv4.o
+obj-$(CONFIG_NFT_REDIR_IPV4) += nft_redir_ipv4.o
 obj-$(CONFIG_NF_TABLES_ARP) += nf_tables_arp.o
 
 # generic IP tables
net/ipv4/netfilter/nft_redir_ipv4.c new file +76 -0

76 lines not on this page · raw message

net/ipv6/netfilter/Kconfig +9 -0
index 462eebb..0dbe5c7 100644
@@ -97,6 +97,15 @@ config NFT_MASQ_IPV6
 	  This is the expression that provides IPv4 masquerading support for
 	  nf_tables.
 
+config NFT_REDIR_IPV6
+	tristate "IPv6 redirect support for nf_tables"
+	depends on NF_TABLES_IPV6
+	depends on NFT_REDIR
+	select NF_NAT_REDIRECT_IPV6
+	help
+	  This is the expression that provides IPv4 redirect support for
+	  nf_tables.
+
 endif # NF_NAT_IPV6
 
 config IP6_NF_IPTABLES
net/ipv6/netfilter/Makefile +1 -0
index 6c2baab..d2ac9f5 100644
@@ -37,6 +37,7 @@ obj-$(CONFIG_NFT_CHAIN_ROUTE_IPV6) += nft_chain_route_ipv6.o
 obj-$(CONFIG_NFT_CHAIN_NAT_IPV6) += nft_chain_nat_ipv6.o
 obj-$(CONFIG_NFT_REJECT_IPV6) += nft_reject_ipv6.o
 obj-$(CONFIG_NFT_MASQ_IPV6) += nft_masq_ipv6.o
+obj-$(CONFIG_NFT_REDIR_IPV6) += nft_redir_ipv6.o
 
 # matches
 obj-$(CONFIG_IP6_NF_MATCH_AH) += ip6t_ah.o
net/netfilter/Kconfig +9 -0
index 1d0131c..d155799 100644
@@ -505,6 +505,15 @@ config NFT_MASQ
 	  This option adds the "masquerade" expression that you can use
 	  to perform NAT in the masquerade flavour.
 
+config NFT_REDIR
+	depends on NF_TABLES
+	depends on NF_CONNTRACK
+	depends on NF_NAT
+	tristate "Netfilter nf_tables redirect support"
+	help
+	  This options adds the "redirect" expression that you can use
+	  to perform NAT in the redirect flavour.
+
 config NFT_NAT
 	depends on NF_TABLES
 	depends on NF_CONNTRACK
net/netfilter/Makefile +1 -0
index a9571be..f3eb468 100644
@@ -88,6 +88,7 @@ obj-$(CONFIG_NFT_HASH)		+= nft_hash.o
 obj-$(CONFIG_NFT_COUNTER)	+= nft_counter.o
 obj-$(CONFIG_NFT_LOG)		+= nft_log.o
 obj-$(CONFIG_NFT_MASQ)		+= nft_masq.o
+obj-$(CONFIG_NFT_REDIR)		+= nft_redir.o
 
 # generic X tables 
 obj-$(CONFIG_NETFILTER_XTABLES) += x_tables.o xt_tcpudp.o
net/netfilter/nft_redir.c new file +93 -0

93 lines not on this page · raw message

maintainer
#3 lore raw

Re: [nf_tables PATCH 3/3] netfilter: nf_tables: add new expression nft_redir

Quoted 26 lines · Arturo Borrero Gonzalez

This new expression provides NAT in the redirect flavour, which is to redirect packets to local machine.

Signed-off-by Arturo Borrero Gonzalez <[email protected]>
---
 include/net/netfilter/nft_redir.h        |   18 ++++++
 include/uapi/linux/netfilter/nf_tables.h |   16 +++++
 net/ipv4/netfilter/Kconfig               |    9 +++
 net/ipv4/netfilter/Makefile              |    1 
 net/ipv4/netfilter/nft_redir_ipv4.c      |   76 +++++++++++++++++++++++++
 net/ipv6/netfilter/Kconfig               |    9 +++
 net/ipv6/netfilter/Makefile              |    1 
 net/netfilter/Kconfig                    |    9 +++
 net/netfilter/Makefile                   |    1 
 net/netfilter/nft_redir.c                |   93 ++++++++++++++++++++++++++++++
 10 files changed, 233 insertions(+)
 create mode 100644 include/net/netfilter/nft_redir.h
 create mode 100644 net/ipv4/netfilter/nft_redir_ipv4.c
 create mode 100644 net/netfilter/nft_redir.c
include/net/netfilter/nft_redir.h new file +0 -0
new file mode 100644
index 0000000..b6695da

include/net/netfilter/nft_redir.h line 7

Quoted 7 lines
include/net/netfilter/nft_redir.h new file +7 -0
@@ -0,0 +1,18 @@
+#ifndef _NFT_REDIR_H_
+#define _NFT_REDIR_H_
+
+struct nft_redir {
+	enum nft_registers	sreg_proto_min:8;
+	enum nft_registers	sreg_proto_max:8;
+	u32			flags;

I think you can use u16 to store the flags. So this consumes only 4 bytes in 32-bits arch.

Quoted 25 lines
include/net/netfilter/nft_redir.h new file +11 -0
+};
+
+extern const struct nla_policy nft_redir_policy[];
+
+int nft_redir_init(const struct nft_ctx *ctx,
+		   const struct nft_expr *expr,
+		   const struct nlattr * const tb[]);
+
+int nft_redir_dump(struct sk_buff *skb, const struct nft_expr *expr);
+
+#endif /* _NFT_REDIR_H_ */
include/uapi/linux/netfilter/nf_tables.h +6 -0
index c26df67..8a96a36 100644
@@ -849,4 +849,20 @@ enum nft_gen_attributes {
 };
 #define NFTA_GEN_MAX		(__NFTA_GEN_MAX - 1)
 
+/**
+ * enum nft_redir_attributes - nf_tables redirect expression netlink attributes
+ *
+ * @NFTA_REDIR_REG_PROTO_MIN: source register of proto range start (NLA_U32: nft_registers)
+ * @NFTA_REDIR_REG_PROTO_MAX: source register of proto range end (NLA_U32: nft_registers)
+ * @NFTA_REDIR_FLAGS: NAT flags (see NF_NAT_RANGE_* in linux/netfilter/nf_nat.h) (NLA_U32)

include/uapi/linux/netfilter/nf_tables.h enum nft_gen_attributes { · line 867

Quoted 10 lines
include/uapi/linux/netfilter/nf_tables.h +10 -0
+ */
+enum nft_redir_attributes {
+	NFTA_REDIR_UNSPEC,
+	NFTA_REDIR_REG_PROTO_MIN,
+	NFTA_REDIR_REG_PROTO_MAX,
+	NFTA_REDIR_FLAGS,
+	__NFTA_REDIR_MAX
+};
+#define NFTA_REDIR_MAX		(__NFTA_REDIR_MAX - 1)
+

Please, place this new chunk after the masq atributes.

Quoted 33 lines
include/uapi/linux/netfilter/nf_tables.h +0 -0
 #endif /* _LINUX_NF_TABLES_H */
net/ipv4/netfilter/Kconfig +9 -0
index a300e2c..8358b2d 100644
@@ -119,6 +119,15 @@ config NFT_MASQ_IPV4
 	  This is the expression that provides IPv4 masquerading support for
 	  nf_tables.
 
+config NFT_REDIR_IPV4
+	tristate "IPv4 redirect support for nf_tables"
+	depends on NF_TABLES_IPV4
+	depends on NFT_REDIR
+	select NF_NAT_REDIRECT_IPV4
+	help
+	  This is the expression that provides IPv4 redirect support for
+	  nf_tables.
+
 config NF_NAT_SNMP_BASIC
 	tristate "Basic SNMP-ALG support"
 	depends on NF_CONNTRACK_SNMP
net/ipv4/netfilter/Makefile +1 -0
index 34e436c..902bcd1 100644
@@ -41,6 +41,7 @@ obj-$(CONFIG_NFT_CHAIN_ROUTE_IPV4) += nft_chain_route_ipv4.o
 obj-$(CONFIG_NFT_CHAIN_NAT_IPV4) += nft_chain_nat_ipv4.o
 obj-$(CONFIG_NFT_REJECT_IPV4) += nft_reject_ipv4.o
 obj-$(CONFIG_NFT_MASQ_IPV4) += nft_masq_ipv4.o
+obj-$(CONFIG_NFT_REDIR_IPV4) += nft_redir_ipv4.o
 obj-$(CONFIG_NF_TABLES_ARP) += nf_tables_arp.o
 
 # generic IP tables

[...]

Quoted 31 lines
net/netfilter/nft_redir.c new file +25 -0
new file mode 100644
index 0000000..1d414a7
@@ -0,0 +1,93 @@
+/*
+ * Copyright (c) 2014 Arturo Borrero Gonzalez <[email protected]>
+ *
+ * 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/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/netlink.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter/nf_tables.h>
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_tables.h>
+#include <net/netfilter/nft_redir.h>
+
+const struct nla_policy nft_redir_policy[NFTA_REDIR_MAX + 1] = {
+	[NFTA_REDIR_REG_PROTO_MIN]	= { .type = NLA_U32 },
+	[NFTA_REDIR_REG_PROTO_MAX]	= { .type = NLA_U32 },
+	[NFTA_REDIR_FLAGS]		= { .type = NLA_U32 },
+};
+EXPORT_SYMBOL_GPL(nft_redir_policy);
+

net/netfilter/nft_redir.c line 35

Quoted 10 lines
net/netfilter/nft_redir.c new file +10 -0
+int nft_redir_init(const struct nft_ctx *ctx,
+		   const struct nft_expr *expr,
+		   const struct nlattr * const tb[])
+{
+	struct nft_redir *priv = nft_expr_priv(expr);
+	int err;
+
+	if (tb[NFTA_REDIR_REG_PROTO_MIN]) {
+		priv->sreg_proto_min = ntohl(nla_get_be32(
+						tb[NFTA_REDIR_REG_PROTO_MIN]));

I prefer this:

		priv->sreg_proto_min =
                        ntohl(nla_get_be32(tb[NFTA_REDIR_REG_PROTO_MIN]));

net/netfilter/nft_redir.c line 39

Quoted 4 lines
net/netfilter/nft_redir.c new file +4 -0
+		err = nft_validate_input_register(priv->sreg_proto_min);
+		if (err < 0)
+			return err;
+	}

No else here? ->sreg_proto_min is left uninitialized.

net/netfilter/nft_redir.c line 43

Quoted 4 lines
net/netfilter/nft_redir.c new file +4 -0
+
+	if (tb[NFTA_REDIR_REG_PROTO_MAX]) {
+		priv->sreg_proto_max = ntohl(nla_get_be32(
+						tb[NFTA_REDIR_REG_PROTO_MAX]));

Same thing here.

net/netfilter/nft_redir.c line 48

Quoted 5 lines
net/netfilter/nft_redir.c new file +5 -0
+		err = nft_validate_input_register(priv->sreg_proto_max);
+		if (err < 0)
+			return err;
+	} else
+		priv->sreg_proto_max = priv->sreg_proto_min;

Missing brackets wrapping around this 'else'.

net/netfilter/nft_redir.c line 56

Quoted 8 lines
net/netfilter/nft_redir.c new file +8 -0
+
+	if (tb[NFTA_REDIR_FLAGS]) {
+		priv->flags = ntohl(nla_get_be32(tb[NFTA_REDIR_FLAGS]));
+		if (priv->flags & ~NF_NAT_RANGE_MASK)
+			return -EINVAL;
+	}
+
+

extra line, remove it.

Quoted 17 lines
net/netfilter/nft_redir.c new file +17 -0
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nft_redir_init);
+
+int nft_redir_dump(struct sk_buff *skb, const struct nft_expr *expr)
+{
+	const struct nft_redir *priv = nft_expr_priv(expr);
+
+	if (priv->sreg_proto_min) {
+		if (nla_put_be32(skb, NFTA_REDIR_REG_PROTO_MIN,
+				 htonl(priv->sreg_proto_min)))
+			goto nla_put_failure;
+		if (nla_put_be32(skb, NFTA_REDIR_REG_PROTO_MAX,
+				 htonl(priv->sreg_proto_max)))
+			goto nla_put_failure;
+	}
+

net/netfilter/nft_redir.c line 83

Quoted 10 lines
net/netfilter/nft_redir.c new file +10 -0
+	if (priv->flags != 0) {
+		if (nla_put_be32(skb, NFTA_REDIR_FLAGS, htonl(priv->flags)))
+			goto nla_put_failure;
+	}
+
+	if (priv->flags == 0)
+		return 0;
+
+	if (nla_put_be32(skb, NFTA_REDIR_FLAGS, htonl(priv->flags)))
+		goto nla_put_failure;

These 10 lines above are freak. I guess you can refactor this to:

        if (priv->flags != 0 &&
            nla_put_...
                goto nla_put_failure;
author
#4 lore raw

Re: [nf_tables PATCH 3/3] netfilter: nf_tables: add new expression nft_redir

Quoted 13 lines · Pablo Neira Ayuso
Quoted 12 lines · Arturo Borrero Gonzalez

This new expression provides NAT in the redirect flavour, which is to redirect packets to local machine.

Signed-off-by Arturo Borrero Gonzalez <[email protected]>
---
 include/net/netfilter/nft_redir.h        |   18 ++++++
 include/uapi/linux/netfilter/nf_tables.h |   16 +++++
 net/ipv4/netfilter/Kconfig               |    9 +++
 net/ipv4/netfilter/Makefile              |    1
 net/ipv4/netfilter/nft_redir_ipv4.c      |   76 +++++++++++++++++++++++++
 net/ipv6/netfilter/Kconfig               |    9 +++
 net/ipv6/netfilter/Makefile              |    1
Quoted 8 lines
Quoted 8 lines
 net/netfilter/Kconfig                    |    9 +++
 net/netfilter/Makefile                   |    1
 net/netfilter/nft_redir.c                |   93 ++++++++++++++++++++++++++++++
 10 files changed, 233 insertions(+)
 create mode 100644 include/net/netfilter/nft_redir.h
 create mode 100644 net/ipv4/netfilter/nft_redir_ipv4.c
 create mode 100644 net/netfilter/nft_redir.c

Hi Pablo,

thanks for your comments. I will address all of them.

BTW, the last chunk you mentioned is clearly poor code, bad reviewed by myself.

regards.

Signature · 5 lines
Arturo Borrero González
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author
#5 lore raw

Re: [nf_tables PATCH 3/3] netfilter: nf_tables: add new expression nft_redir

In reply to Pablo Neira Ayuso
Quoted 158 lines · Pablo Neira Ayuso
Quoted 26 lines · Arturo Borrero Gonzalez

This new expression provides NAT in the redirect flavour, which is to redirect packets to local machine.

Signed-off-by Arturo Borrero Gonzalez <[email protected]>
---
 include/net/netfilter/nft_redir.h        |   18 ++++++
 include/uapi/linux/netfilter/nf_tables.h |   16 +++++
 net/ipv4/netfilter/Kconfig               |    9 +++
 net/ipv4/netfilter/Makefile              |    1
 net/ipv4/netfilter/nft_redir_ipv4.c      |   76 +++++++++++++++++++++++++
 net/ipv6/netfilter/Kconfig               |    9 +++
 net/ipv6/netfilter/Makefile              |    1
 net/netfilter/Kconfig                    |    9 +++
 net/netfilter/Makefile                   |    1
 net/netfilter/nft_redir.c                |   93 ++++++++++++++++++++++++++++++
 10 files changed, 233 insertions(+)
 create mode 100644 include/net/netfilter/nft_redir.h
 create mode 100644 net/ipv4/netfilter/nft_redir_ipv4.c
 create mode 100644 net/netfilter/nft_redir.c
include/net/netfilter/nft_redir.h new file +0 -0
new file mode 100644
index 0000000..b6695da

include/net/netfilter/nft_redir.h line 7

Quoted 7 lines
include/net/netfilter/nft_redir.h new file +7 -0
@@ -0,0 +1,18 @@
+#ifndef _NFT_REDIR_H_
+#define _NFT_REDIR_H_
+
+struct nft_redir {
+     enum nft_registers      sreg_proto_min:8;
+     enum nft_registers      sreg_proto_max:8;
+     u32                     flags;

I think you can use u16 to store the flags. So this consumes only 4 bytes in 32-bits arch.

Quoted 25 lines
include/net/netfilter/nft_redir.h new file +11 -0
+};
+
+extern const struct nla_policy nft_redir_policy[];
+
+int nft_redir_init(const struct nft_ctx *ctx,
+                const struct nft_expr *expr,
+                const struct nlattr * const tb[]);
+
+int nft_redir_dump(struct sk_buff *skb, const struct nft_expr *expr);
+
+#endif /* _NFT_REDIR_H_ */
include/uapi/linux/netfilter/nf_tables.h +6 -0
index c26df67..8a96a36 100644
@@ -849,4 +849,20 @@ enum nft_gen_attributes {
 };
 #define NFTA_GEN_MAX         (__NFTA_GEN_MAX - 1)
 
+/**
+ * enum nft_redir_attributes - nf_tables redirect expression netlink attributes
+ *
+ * @NFTA_REDIR_REG_PROTO_MIN: source register of proto range start (NLA_U32: nft_registers)
+ * @NFTA_REDIR_REG_PROTO_MAX: source register of proto range end (NLA_U32: nft_registers)
+ * @NFTA_REDIR_FLAGS: NAT flags (see NF_NAT_RANGE_* in linux/netfilter/nf_nat.h) (NLA_U32)

include/uapi/linux/netfilter/nf_tables.h enum nft_gen_attributes { · line 867

Quoted 10 lines
include/uapi/linux/netfilter/nf_tables.h +10 -0
+ */
+enum nft_redir_attributes {
+     NFTA_REDIR_UNSPEC,
+     NFTA_REDIR_REG_PROTO_MIN,
+     NFTA_REDIR_REG_PROTO_MAX,
+     NFTA_REDIR_FLAGS,
+     __NFTA_REDIR_MAX
+};
+#define NFTA_REDIR_MAX               (__NFTA_REDIR_MAX - 1)
+

Please, place this new chunk after the masq atributes.

Quoted 33 lines
include/uapi/linux/netfilter/nf_tables.h +0 -0
 #endif /* _LINUX_NF_TABLES_H */
net/ipv4/netfilter/Kconfig +9 -0
index a300e2c..8358b2d 100644
@@ -119,6 +119,15 @@ config NFT_MASQ_IPV4
        This is the expression that provides IPv4 masquerading support for
        nf_tables.
 
+config NFT_REDIR_IPV4
+     tristate "IPv4 redirect support for nf_tables"
+     depends on NF_TABLES_IPV4
+     depends on NFT_REDIR
+     select NF_NAT_REDIRECT_IPV4
+     help
+       This is the expression that provides IPv4 redirect support for
+       nf_tables.
+
 config NF_NAT_SNMP_BASIC
      tristate "Basic SNMP-ALG support"
      depends on NF_CONNTRACK_SNMP
net/ipv4/netfilter/Makefile +1 -0
index 34e436c..902bcd1 100644
@@ -41,6 +41,7 @@ obj-$(CONFIG_NFT_CHAIN_ROUTE_IPV4) += nft_chain_route_ipv4.o
 obj-$(CONFIG_NFT_CHAIN_NAT_IPV4) += nft_chain_nat_ipv4.o
 obj-$(CONFIG_NFT_REJECT_IPV4) += nft_reject_ipv4.o
 obj-$(CONFIG_NFT_MASQ_IPV4) += nft_masq_ipv4.o
+obj-$(CONFIG_NFT_REDIR_IPV4) += nft_redir_ipv4.o
 obj-$(CONFIG_NF_TABLES_ARP) += nf_tables_arp.o
 
 # generic IP tables

[...]

Quoted 31 lines
net/netfilter/nft_redir.c new file +25 -0
new file mode 100644
index 0000000..1d414a7
@@ -0,0 +1,93 @@
+/*
+ * Copyright (c) 2014 Arturo Borrero Gonzalez <[email protected]>
+ *
+ * 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/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/netlink.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter/nf_tables.h>
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_tables.h>
+#include <net/netfilter/nft_redir.h>
+
+const struct nla_policy nft_redir_policy[NFTA_REDIR_MAX + 1] = {
+     [NFTA_REDIR_REG_PROTO_MIN]      = { .type = NLA_U32 },
+     [NFTA_REDIR_REG_PROTO_MAX]      = { .type = NLA_U32 },
+     [NFTA_REDIR_FLAGS]              = { .type = NLA_U32 },
+};
+EXPORT_SYMBOL_GPL(nft_redir_policy);
+

net/netfilter/nft_redir.c line 35

Quoted 10 lines
net/netfilter/nft_redir.c new file +10 -0
+int nft_redir_init(const struct nft_ctx *ctx,
+                const struct nft_expr *expr,
+                const struct nlattr * const tb[])
+{
+     struct nft_redir *priv = nft_expr_priv(expr);
+     int err;
+
+     if (tb[NFTA_REDIR_REG_PROTO_MIN]) {
+             priv->sreg_proto_min = ntohl(nla_get_be32(
+                                             tb[NFTA_REDIR_REG_PROTO_MIN]));

I prefer this:

                priv->sreg_proto_min =
                        ntohl(nla_get_be32(tb[NFTA_REDIR_REG_PROTO_MIN]));
Quoted 7 lines

net/netfilter/nft_redir.c line 39

Quoted 4 lines
net/netfilter/nft_redir.c new file +4 -0
+             err = nft_validate_input_register(priv->sreg_proto_min);
+             if (err < 0)
+                     return err;
+     }

No else here? ->sreg_proto_min is left uninitialized.

Such behaviour is copied from nft_nat.
I'm not sure to which value I should initialize sreg_proto_min.

regards.

Signature · 5 lines
Arturo Borrero González
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maintainer
#6 lore raw

Re: [nf_tables PATCH 3/3] netfilter: nf_tables: add new expression nft_redir

Quoted 23 lines · Arturo Borrero Gonzalez
Quoted 22 lines · Pablo Neira Ayuso

net/netfilter/nft_redir.c line 35

Quoted 10 lines
net/netfilter/nft_redir.c new file +10 -0
+int nft_redir_init(const struct nft_ctx *ctx,
+                const struct nft_expr *expr,
+                const struct nlattr * const tb[])
+{
+     struct nft_redir *priv = nft_expr_priv(expr);
+     int err;
+
+     if (tb[NFTA_REDIR_REG_PROTO_MIN]) {
+             priv->sreg_proto_min = ntohl(nla_get_be32(
+                                             tb[NFTA_REDIR_REG_PROTO_MIN]));

I prefer this:

                priv->sreg_proto_min =
                        ntohl(nla_get_be32(tb[NFTA_REDIR_REG_PROTO_MIN]));
Quoted 4 lines
net/netfilter/nft_redir.c new file +4 -0
+             err = nft_validate_input_register(priv->sreg_proto_min);
+             if (err < 0)
+                     return err;
+     }
Quoted 5 lines
Quoted 2 lines

No else here? ->sreg_proto_min is left uninitialized.

Such behaviour is copied from nft_nat.
I'm not sure to which value I should initialize sreg_proto_min.

This seems fine for redirect as ->sreg_proto_min will be zero. Keep in mind that we have to support redirect with no port range specified. I mean, iptables supports -j REDIRECT without arguments.

Regarding nft_nat, not good. I'm going to send a patch to reject invalid configurations. At least one of the NFTA_NAT_REG_*_MIN needs to be specified.

maintainer
#7 lore raw
In reply to Arturo Borrero Gonzalez
Quoted 107 lines · Arturo Borrero Gonzalez

The xt_REDIRECT can be seen as a NAT flavour (like masquerade).

This patch refactors the IPv4 code so it can be usable both from xt and nf_tables.

A similar patch follows-up to handle IPv6.

Signed-off-by Arturo Borrero Gonzalez <[email protected]>
---
 include/net/netfilter/ipv4/nf_nat_redirect.h |    9 +++
 net/ipv4/netfilter/Kconfig                   |    6 ++
 net/ipv4/netfilter/Makefile                  |    1 
 net/ipv4/netfilter/nf_nat_redirect_ipv4.c    |   80 ++++++++++++++++++++++++++
 net/netfilter/Kconfig                        |    1 
 net/netfilter/xt_REDIRECT.c                  |   44 +-------------
 6 files changed, 99 insertions(+), 42 deletions(-)
 create mode 100644 include/net/netfilter/ipv4/nf_nat_redirect.h
 create mode 100644 net/ipv4/netfilter/nf_nat_redirect_ipv4.c
include/net/netfilter/ipv4/nf_nat_redirect.h new file +9 -0
new file mode 100644
index 0000000..19e1df3
@@ -0,0 +1,9 @@
+#ifndef _NF_NAT_REDIRECT_IPV4_H_
+#define _NF_NAT_REDIRECT_IPV4_H_
+
+unsigned int
+nf_nat_redirect_ipv4(struct sk_buff *skb,
+		     const struct nf_nat_ipv4_multi_range_compat *mr,
+		     unsigned int hooknum);
+
+#endif /* _NF_NAT_REDIRECT_IPV4_H_ */
net/ipv4/netfilter/Kconfig +6 -0
index 4c019d5..a300e2c 100644
@@ -104,6 +104,12 @@ config NF_NAT_MASQUERADE_IPV4
 	  This is the kernel functionality to provide NAT in the masquerade
 	  flavour (automatic source address selection).
 
+config NF_NAT_REDIRECT_IPV4
+	tristate "IPv4 redirect support"
+	help
+	  This is the kernel functionality to provide NAT in the redirect
+	  flavour (redirect packets to local machine).
+
 config NFT_MASQ_IPV4
 	tristate "IPv4 masquerading support for nf_tables"
 	depends on NF_TABLES_IPV4
net/ipv4/netfilter/Makefile +1 -0
index f4cef5a..34e436c 100644
@@ -31,6 +31,7 @@ obj-$(CONFIG_NF_NAT_H323) += nf_nat_h323.o
 obj-$(CONFIG_NF_NAT_PPTP) += nf_nat_pptp.o
 obj-$(CONFIG_NF_NAT_SNMP_BASIC) += nf_nat_snmp_basic.o
 obj-$(CONFIG_NF_NAT_MASQUERADE_IPV4) += nf_nat_masquerade_ipv4.o
+obj-$(CONFIG_NF_NAT_REDIRECT_IPV4) += nf_nat_redirect_ipv4.o
 
 # NAT protocols (nf_nat)
 obj-$(CONFIG_NF_NAT_PROTO_GRE) += nf_nat_proto_gre.o
net/ipv4/netfilter/nf_nat_redirect_ipv4.c new file +38 -0
new file mode 100644
index 0000000..317f59c
@@ -0,0 +1,80 @@
+/*
+ * (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2006 Netfilter Core Team <[email protected]>
+ * Copyright (c) 2011 Patrick McHardy <[email protected]>
+ *
+ * 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.
+ *
+ * Based on Rusty Russell's IPv4 REDIRECT target. Development of IPv6
+ * NAT funded by Astaro.
+ */
+
+#include <linux/if.h>
+#include <linux/inetdevice.h>
+#include <linux/ip.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/netfilter.h>
+#include <linux/types.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter/x_tables.h>
+#include <net/addrconf.h>
+#include <net/checksum.h>
+#include <net/protocol.h>
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/ipv4/nf_nat_redirect.h>
+
+unsigned int
+nf_nat_redirect_ipv4(struct sk_buff *skb,
+		     const struct nf_nat_ipv4_multi_range_compat *mr,
+		     unsigned int hooknum)
+{
+	struct nf_conn *ct;
+	enum ip_conntrack_info ctinfo;
+	__be32 newdst;
+	struct nf_nat_range newrange;

net/ipv4/netfilter/nf_nat_redirect_ipv4.c line 48

Quoted 10 lines
net/ipv4/netfilter/nf_nat_redirect_ipv4.c new file +10 -0
+
+	NF_CT_ASSERT(hooknum == NF_INET_PRE_ROUTING ||
+		     hooknum == NF_INET_LOCAL_OUT);
+
+	ct = nf_ct_get(skb, &ctinfo);
+	NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
+
+	/* Local packets: make them go to loopback */
+	if (hooknum == NF_INET_LOCAL_OUT)
+		newdst = htonl(0x7F000001);

Please, fix coding style. This needs to be:

	if (hooknum == NF_INET_LOCAL_OUT) {
		newdst = htonl(0x7F000001);
        } else {
                ...

Basically, if any of the branches contains more than one line, we have to use the bracket in both.

I know this is not your fault since you're just copying and pasting this code. But I think this is a good chance to address this.

Quoted 37 lines
net/ipv4/netfilter/nf_nat_redirect_ipv4.c new file +32 -0
+	else {
+		struct in_device *indev;
+		struct in_ifaddr *ifa;
+
+		newdst = 0;
+
+		rcu_read_lock();
+		indev = __in_dev_get_rcu(skb->dev);
+		if (indev && (ifa = indev->ifa_list))
+			newdst = ifa->ifa_local;
+		rcu_read_unlock();
+
+		if (!newdst)
+			return NF_DROP;
+	}
+
+	/* Transfer from original range. */
+	memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
+	memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
+	newrange.flags	     = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
+	newrange.min_addr.ip = newdst;
+	newrange.max_addr.ip = newdst;
+	newrange.min_proto   = mr->range[0].min;
+	newrange.max_proto   = mr->range[0].max;
+
+	/* Hand modified range to generic setup. */
+	return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST);
+}
+EXPORT_SYMBOL_GPL(nf_nat_redirect_ipv4);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Patrick McHardy <[email protected]>");
net/netfilter/Kconfig +0 -0
index ae5096a..bc0726d 100644

net/netfilter/Kconfig config NETFILTER_XT_TARGET_RATEEST · line 838

Quoted 4 lines
net/netfilter/Kconfig +1 -0
@@ -835,6 +835,7 @@ config NETFILTER_XT_TARGET_RATEEST
 config NETFILTER_XT_TARGET_REDIRECT
 	tristate "REDIRECT target support"
 	depends on NF_NAT
+	depends on NF_NAT_REDIRECT_IPV4

This needs to be 'select NF_NAT_REDIRECT_IPV4' instead.

Quoted 24 lines
net/netfilter/Kconfig +0 -0
 	---help---
 	REDIRECT is a special case of NAT: all incoming connections are
 	mapped onto the incoming interface's address, causing the packets to
net/netfilter/xt_REDIRECT.c +1 -5
index 22a1030..b4ffac5 100644
@@ -26,6 +26,7 @@
 #include <net/checksum.h>
 #include <net/protocol.h>
 #include <net/netfilter/nf_nat.h>
+#include <net/netfilter/ipv4/nf_nat_redirect.h>
 
 static const struct in6_addr loopback_addr = IN6ADDR_LOOPBACK_INIT;
 

@@ -98,48 +99,7 @@ static int redirect_tg4_check(const struct xt_tgchk_param *par)
 static unsigned int
 redirect_tg4(struct sk_buff *skb, const struct xt_action_param *par)
 {
-	struct nf_conn *ct;
-	enum ip_conntrack_info ctinfo;
-	__be32 newdst;
-	const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
-	struct nf_nat_range newrange;

net/netfilter/xt_REDIRECT.c static int redirect_tg4_check(const struct xt_tgchk_param *par) · line 115

Quoted 10 lines
net/netfilter/xt_REDIRECT.c +0 -10
-
-	NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING ||
-		     par->hooknum == NF_INET_LOCAL_OUT);
-
-	ct = nf_ct_get(skb, &ctinfo);
-	NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
-
-	/* Local packets: make them go to loopback */
-	if (par->hooknum == NF_INET_LOCAL_OUT)
-		newdst = htonl(0x7F000001);

Same coding style nitpick here.

Apart from those comment, this looks good to me. Thanks Arturo.