[RESEND PATCH net-next v7 0/3] Add RFC-7597 Section 5.1 PSID support

[RESEND PATCH net-next v7 0/3] Add RFC-7597 Section 5.1 PSID support

[Cole Dishington]

Resend to add v7 to subject to detect cover letter in patchwork.

Cole Dishington (3):
  net: netfilter: Add RFC-7597 Section 5.1 PSID support xtables API
  net: netfilter: Add RFC-7597 Section 5.1 PSID support
  selftests: netfilter: Add RFC-7597 Section 5.1 PSID selftests

 include/uapi/linux/netfilter/nf_nat.h         |   3 +-
 net/netfilter/nf_nat_core.c                   |  39 +++-
 net/netfilter/nf_nat_masquerade.c             |  27 ++-
 net/netfilter/xt_MASQUERADE.c                 |  44 ++++-
 .../netfilter/nat_masquerade_psid.sh          | 182 ++++++++++++++++++
 5 files changed, 283 insertions(+), 12 deletions(-)
 create mode 100644 tools/testing/selftests/netfilter/nat_masquerade_psid.sh

-- 
2.33.0

[RESEND PATCH net-next v7 1/3] net: netfilter: Add RFC-7597 Section 5.1 PSID support xtables API

[Cole Dishington]

Add support for revision 2 of xtables masquerade extension.

Co-developed-by: Anthony Lineham <anthony.lineham@alliedtelesis.co.nz>
Signed-off-by: Anthony Lineham <anthony.lineham@alliedtelesis.co.nz>
Co-developed-by: Scott Parlane <scott.parlane@alliedtelesis.co.nz>
Signed-off-by: Scott Parlane <scott.parlane@alliedtelesis.co.nz>
Signed-off-by: Blair Steven <blair.steven@alliedtelesis.co.nz>
Signed-off-by: Cole Dishington <Cole.Dishington@alliedtelesis.co.nz>
---
 include/uapi/linux/netfilter/nf_nat.h |  3 +-
 net/netfilter/xt_MASQUERADE.c         | 44 ++++++++++++++++++++++++---
 2 files changed, 41 insertions(+), 6 deletions(-)

diff --git a/include/uapi/linux/netfilter/nf_nat.h b/include/uapi/linux/netfilter/nf_nat.h
index a64586e77b24..660e53ffdb57 100644
--- a/include/uapi/linux/netfilter/nf_nat.h
+++ b/include/uapi/linux/netfilter/nf_nat.h
@@ -12,6 +12,7 @@
 #define NF_NAT_RANGE_PROTO_RANDOM_FULLY		(1 << 4)
 #define NF_NAT_RANGE_PROTO_OFFSET		(1 << 5)
 #define NF_NAT_RANGE_NETMAP			(1 << 6)
+#define NF_NAT_RANGE_PSID			(1 << 7)
 
 #define NF_NAT_RANGE_PROTO_RANDOM_ALL		\
 	(NF_NAT_RANGE_PROTO_RANDOM | NF_NAT_RANGE_PROTO_RANDOM_FULLY)
@@ -20,7 +21,7 @@
 	(NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED |	\
 	 NF_NAT_RANGE_PROTO_RANDOM | NF_NAT_RANGE_PERSISTENT |	\
 	 NF_NAT_RANGE_PROTO_RANDOM_FULLY | NF_NAT_RANGE_PROTO_OFFSET | \
-	 NF_NAT_RANGE_NETMAP)
+	 NF_NAT_RANGE_NETMAP | NF_NAT_RANGE_PSID)
 
 struct nf_nat_ipv4_range {
 	unsigned int			flags;
diff --git a/net/netfilter/xt_MASQUERADE.c b/net/netfilter/xt_MASQUERADE.c
index eae05c178336..dc6870ca2b71 100644
--- a/net/netfilter/xt_MASQUERADE.c
+++ b/net/netfilter/xt_MASQUERADE.c
@@ -16,7 +16,7 @@ MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
 MODULE_DESCRIPTION("Xtables: automatic-address SNAT");
 
 /* FIXME: Multiple targets. --RR */
-static int masquerade_tg_check(const struct xt_tgchk_param *par)
+static int masquerade_tg_check_v0(const struct xt_tgchk_param *par)
 {
 	const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
 
@@ -31,8 +31,19 @@ static int masquerade_tg_check(const struct xt_tgchk_param *par)
 	return nf_ct_netns_get(par->net, par->family);
 }
 
+static int masquerade_tg_check_v1(const struct xt_tgchk_param *par)
+{
+	const struct nf_nat_range2 *range = par->targinfo;
+
+	if (range->flags & NF_NAT_RANGE_MAP_IPS) {
+		pr_debug("bad MAP_IPS.\n");
+		return -EINVAL;
+	}
+	return nf_ct_netns_get(par->net, par->family);
+}
+
 static unsigned int
-masquerade_tg(struct sk_buff *skb, const struct xt_action_param *par)
+masquerade_tg_v0(struct sk_buff *skb, const struct xt_action_param *par)
 {
 	struct nf_nat_range2 range;
 	const struct nf_nat_ipv4_multi_range_compat *mr;
@@ -46,6 +57,15 @@ masquerade_tg(struct sk_buff *skb, const struct xt_action_param *par)
 				      xt_out(par));
 }
 
+static unsigned int
+masquerade_tg_v1(struct sk_buff *skb, const struct xt_action_param *par)
+{
+	const struct nf_nat_range2 *range = par->targinfo;
+
+	return nf_nat_masquerade_ipv4(skb, xt_hooknum(par), range,
+				      xt_out(par));
+}
+
 static void masquerade_tg_destroy(const struct xt_tgdtor_param *par)
 {
 	nf_ct_netns_put(par->net, par->family);
@@ -73,6 +93,7 @@ static struct xt_target masquerade_tg_reg[] __read_mostly = {
 	{
 #if IS_ENABLED(CONFIG_IPV6)
 		.name		= "MASQUERADE",
+		.revision	= 0,
 		.family		= NFPROTO_IPV6,
 		.target		= masquerade_tg6,
 		.targetsize	= sizeof(struct nf_nat_range),
@@ -84,15 +105,28 @@ static struct xt_target masquerade_tg_reg[] __read_mostly = {
 	}, {
 #endif
 		.name		= "MASQUERADE",
+		.revision	= 0,
 		.family		= NFPROTO_IPV4,
-		.target		= masquerade_tg,
+		.target		= masquerade_tg_v0,
 		.targetsize	= sizeof(struct nf_nat_ipv4_multi_range_compat),
 		.table		= "nat",
 		.hooks		= 1 << NF_INET_POST_ROUTING,
-		.checkentry	= masquerade_tg_check,
+		.checkentry	= masquerade_tg_check_v0,
 		.destroy	= masquerade_tg_destroy,
 		.me		= THIS_MODULE,
-	}
+	},
+	{
+		.name		= "MASQUERADE",
+		.revision	= 1,
+		.family		= NFPROTO_IPV4,
+		.target		= masquerade_tg_v1,
+		.targetsize	= sizeof(struct nf_nat_range2),
+		.table		= "nat",
+		.hooks		= 1 << NF_INET_POST_ROUTING,
+		.checkentry	= masquerade_tg_check_v1,
+		.destroy	= masquerade_tg_destroy,
+		.me		= THIS_MODULE,
+	},
 };
 
 static int __init masquerade_tg_init(void)
-- 
2.33.0

[RESEND PATCH net-next v7 2/3] net: netfilter: Add RFC-7597 Section 5.1 PSID support

[Cole Dishington]

Adds support for masquerading into a smaller subset of ports -
defined by the PSID values from RFC-7597 Section 5.1. This is part of
the support for MAP-E and Lightweight 4over6, which allows multiple
devices to share an IPv4 address by splitting the L4 port / id into
ranges.

Co-developed-by: Anthony Lineham <anthony.lineham@alliedtelesis.co.nz>
Signed-off-by: Anthony Lineham <anthony.lineham@alliedtelesis.co.nz>
Co-developed-by: Scott Parlane <scott.parlane@alliedtelesis.co.nz>
Signed-off-by: Scott Parlane <scott.parlane@alliedtelesis.co.nz>
Signed-off-by: Blair Steven <blair.steven@alliedtelesis.co.nz>
Signed-off-by: Cole Dishington <Cole.Dishington@alliedtelesis.co.nz>
Reviewed-by: Florian Westphal <fw@strlen.de>
---
 net/netfilter/nf_nat_core.c       | 39 +++++++++++++++++++++++++++----
 net/netfilter/nf_nat_masquerade.c | 27 +++++++++++++++++++--
 2 files changed, 60 insertions(+), 6 deletions(-)

diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c
index b7c3c902290f..c0fb9f3a8c54 100644
--- a/net/netfilter/nf_nat_core.c
+++ b/net/netfilter/nf_nat_core.c
@@ -232,13 +232,36 @@ static bool nf_nat_inet_in_range(const struct nf_conntrack_tuple *t,
 static bool l4proto_in_range(const struct nf_conntrack_tuple *tuple,
 			     enum nf_nat_manip_type maniptype,
 			     const union nf_conntrack_man_proto *min,
-			     const union nf_conntrack_man_proto *max)
+			     const union nf_conntrack_man_proto *max,
+			     const union nf_conntrack_man_proto *base,
+			     bool is_psid)
 {
 	__be16 port;
+	u16 psid, psid_mask, offset_mask;
+
+	/* In this case we are in PSID mode, avoid checking all ranges by computing bitmasks */
+	if (is_psid) {
+		u32 power_j = ntohs(max->all) - ntohs(min->all) + 1;
+		u32 offset = ntohs(base->all);
+		u16 power_a;
+
+		if (offset == 0)
+			offset = 1 << 16;
+
+		power_a = (1 << 16) / offset;
+		offset_mask = (power_a - 1) * offset;
+		psid_mask = ((offset / power_j) << 1) - 1;
+		psid = ntohs(min->all) & psid_mask;
+	}
 
 	switch (tuple->dst.protonum) {
 	case IPPROTO_ICMP:
 	case IPPROTO_ICMPV6:
+		if (is_psid) {
+			return (offset_mask == 0 ||
+				(ntohs(tuple->src.u.icmp.id) & offset_mask) != 0) &&
+				((ntohs(tuple->src.u.icmp.id) & psid_mask) == psid);
+		}
 		return ntohs(tuple->src.u.icmp.id) >= ntohs(min->icmp.id) &&
 		       ntohs(tuple->src.u.icmp.id) <= ntohs(max->icmp.id);
 	case IPPROTO_GRE: /* all fall though */
@@ -252,6 +275,10 @@ static bool l4proto_in_range(const struct nf_conntrack_tuple *tuple,
 		else
 			port = tuple->dst.u.all;
 
+		if (is_psid) {
+			return (offset_mask == 0 || (ntohs(port) & offset_mask) != 0) &&
+				((ntohs(port) & psid_mask) == psid);
+		}
 		return ntohs(port) >= ntohs(min->all) &&
 		       ntohs(port) <= ntohs(max->all);
 	default:
@@ -276,7 +303,8 @@ static int in_range(const struct nf_conntrack_tuple *tuple,
 		return 1;
 
 	return l4proto_in_range(tuple, NF_NAT_MANIP_SRC,
-				&range->min_proto, &range->max_proto);
+				&range->min_proto, &range->max_proto, &range->base_proto,
+				range->flags & NF_NAT_RANGE_PSID);
 }
 
 static inline int
@@ -569,8 +597,11 @@ get_unique_tuple(struct nf_conntrack_tuple *tuple,
 		if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
 			if (!(range->flags & NF_NAT_RANGE_PROTO_OFFSET) &&
 			    l4proto_in_range(tuple, maniptype,
-			          &range->min_proto,
-			          &range->max_proto) &&
+				  &range->min_proto,
+				  &range->max_proto,
+				  &range->base_proto,
+				  range->flags &
+				  NF_NAT_RANGE_PSID) &&
 			    (range->min_proto.all == range->max_proto.all ||
 			     !nf_nat_used_tuple(tuple, ct)))
 				return;
diff --git a/net/netfilter/nf_nat_masquerade.c b/net/netfilter/nf_nat_masquerade.c
index 8e8a65d46345..19a4754cda76 100644
--- a/net/netfilter/nf_nat_masquerade.c
+++ b/net/netfilter/nf_nat_masquerade.c
@@ -55,8 +55,31 @@ nf_nat_masquerade_ipv4(struct sk_buff *skb, unsigned int hooknum,
 	newrange.flags       = range->flags | NF_NAT_RANGE_MAP_IPS;
 	newrange.min_addr.ip = newsrc;
 	newrange.max_addr.ip = newsrc;
-	newrange.min_proto   = range->min_proto;
-	newrange.max_proto   = range->max_proto;
+
+	if (range->flags & NF_NAT_RANGE_PSID) {
+		u16 base = ntohs(range->base_proto.all);
+		u16 min =  ntohs(range->min_proto.all);
+		u16 off = 0;
+
+		/* xtables should stop base > 2^15 by enforcement of
+		 * 0 <= offset_len < 16 argument, with offset_len=0
+		 * as a special case inwhich base=0.
+		 */
+		if (WARN_ON_ONCE(base > (1 << 15)))
+			return NF_DROP;
+
+		/* If offset=0, port range is in one contiguous block */
+		if (base)
+			off = prandom_u32_max(((1 << 16) / base) - 1);
+
+		newrange.min_proto.all   = htons(min + base * off);
+		newrange.max_proto.all   = htons(ntohs(newrange.min_proto.all) + ntohs(range->max_proto.all) - min);
+		newrange.base_proto      = range->base_proto;
+		newrange.flags           = newrange.flags | NF_NAT_RANGE_PROTO_SPECIFIED;
+	} else {
+		newrange.min_proto       = range->min_proto;
+		newrange.max_proto       = range->max_proto;
+	}
 
 	/* Hand modified range to generic setup. */
 	return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC);
-- 
2.33.0

[RESEND PATCH net-next v7 3/3] selftests: netfilter: Add RFC-7597 Section 5.1 PSID selftests

[Cole Dishington]

Add selftests for masquerading into a smaller subset of ports defined by
PSID.

Signed-off-by: Cole Dishington <Cole.Dishington@alliedtelesis.co.nz>
---
 .../netfilter/nat_masquerade_psid.sh          | 182 ++++++++++++++++++
 1 file changed, 182 insertions(+)
 create mode 100644 tools/testing/selftests/netfilter/nat_masquerade_psid.sh

diff --git a/tools/testing/selftests/netfilter/nat_masquerade_psid.sh b/tools/testing/selftests/netfilter/nat_masquerade_psid.sh
new file mode 100644
index 000000000000..56c1b509caf6
--- /dev/null
+++ b/tools/testing/selftests/netfilter/nat_masquerade_psid.sh
@@ -0,0 +1,182 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# <:copyright-gpl
+# Copyright (C) 2021 Allied Telesis Labs NZ
+#
+# check that NAT can masquerade using PSID defined ranges.
+#
+# Setup is:
+#
+# nsclient1(veth0) -> (veth1)nsrouter(veth2) -> (veth0)nsclient2
+# Setup a nat masquerade rule with psid defined ranges.
+#
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+ret=0
+ns_all="nsclient1 nsrouter nsclient2"
+
+readonly infile="$(mktemp)"
+readonly outfile="$(mktemp)"
+readonly datalen=32
+readonly server_port=8080
+
+conntrack -V > /dev/null 2>&1
+if [ $? -ne 0 ];then
+	echo "SKIP: Could not run test without conntrack tool"
+	exit $ksft_skip
+fi
+
+iptables --version > /dev/null 2>&1
+if [ $? -ne 0 ];then
+	echo "SKIP: Could not run test without iptables tool"
+	exit $ksft_skip
+fi
+
+ip -Version > /dev/null 2>&1
+if [ $? -ne 0 ];then
+	echo "SKIP: Could not run test without ip tool"
+	exit $ksft_skip
+fi
+
+ipv4() {
+	echo -n 192.168.$1.$2
+}
+
+cleanup() {
+	for n in $ns_all; do ip netns del $n;done
+
+	if [ -f "${outfile}" ]; then
+		rm "$outfile"
+	fi
+	if [ -f "${infile}" ]; then
+		rm "$infile"
+	fi
+}
+
+server_listen() {
+	ip netns exec nsclient2 nc -l -p "$server_port" > "$outfile" &
+	server_pid=$!
+	sleep 0.2
+}
+
+client_connect() {
+	ip netns exec nsclient1 timeout 2 nc -w 1 -p "$port" $(ipv4 2 2) "$server_port" < $infile
+}
+
+verify_data() {
+	local _ret=0
+	wait "$server_pid"
+	cmp "$infile" "$outfile" 2>/dev/null
+	_ret=$?
+	rm "$outfile"
+	return $_ret
+}
+
+test_service() {
+	server_listen
+	client_connect
+	verify_data
+}
+
+check_connection() {
+	local _ret=0
+	entry=$(ip netns exec nsrouter conntrack -p tcp --sport $port -L 2>&1)
+	entry=${entry##*sport=8080 dport=}
+	entry=${entry%% *}
+
+	if [[ "x$(( ($entry & $psid_mask) / $two_power_j ))" != "x$psid" ]]; then
+		_ret=1
+		echo "Failed psid mask check for $offset_len:$psid:$psid_length with port $entry"
+	fi
+
+	if [[ "x$_ret" = "x0" ]] &&
+	   [[ "x$offset_mask" != "x0" -a "x$(( ($entry & $offset_mask) ))" == "x0" ]]; then
+		_ret=1
+		echo "Failed offset mask check for $offset_len:$psid:$psid_length with port $entry"
+	fi
+	return $_ret
+}
+
+run_test() {
+	ip netns exec nsrouter iptables -A FORWARD -i veth1 -j ACCEPT
+	ip netns exec nsrouter iptables -P FORWARD DROP
+	ip netns exec nsrouter iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT
+	ip netns exec nsrouter iptables -t nat --new psid
+	ip netns exec nsrouter iptables -t nat --insert psid -j MASQUERADE \
+		--psid $offset_len:$psid:$psid_length
+	ip netns exec nsrouter iptables -t nat -I POSTROUTING -o veth2 -j psid
+
+	# calculate psid mask
+	offset=$(( 1 << (16 - $offset_len) ))
+	two_power_j=$(( $offset / (1 << $psid_length) ))
+	offset_mask=$(( ( (1 << $offset_len) - 1 ) << (16 - $offset_len) ))
+	psid_mask=$(( ( (1 << $psid_length) - 1) * $two_power_j ))
+
+	# Create file
+	dd if=/dev/urandom of="${infile}" bs="${datalen}" count=1 >/dev/null 2>&1
+
+	# Test multiple ports
+	for p in 1 2 3 4 5; do
+		port=1080$p
+
+		test_service
+		if [ $? -ne 0 ]; then
+			ret=1
+			break
+		fi
+
+		check_connection
+		if [ $? -ne 0 ]; then
+			ret=1
+			break
+		fi
+	done
+
+	# tidy up test rules
+	ip netns exec nsrouter iptables -F
+	ip netns exec nsrouter iptables -t nat -F
+	ip netns exec nsrouter iptables -t nat -X psid
+}
+
+for n in $ns_all; do
+	ip netns add $n
+	ip -net $n link set lo up
+done
+
+for i in 1 2; do
+	ip link add veth0 netns nsclient$i type veth peer name veth$i netns nsrouter
+
+	ip -net nsclient$i link set veth0 up
+	ip -net nsclient$i addr add $(ipv4 $i 2)/24 dev veth0
+
+	ip -net nsrouter link set veth$i up
+	ip -net nsrouter addr add $(ipv4 $i 1)/24 dev veth$i
+done
+
+ip -net nsclient1 route add default via $(ipv4 1 1)
+ip -net nsclient2 route add default via $(ipv4 2 1)
+
+ip netns exec nsrouter sysctl -q net.ipv4.conf.all.forwarding=1
+
+offset_len=0
+psid_length=8
+for psid in 0 52; do
+	run_test
+	if [ $? -ne 0 ]; then
+		break
+	fi
+done
+
+offset_len=6
+psid_length=8
+for psid in 0 52; do
+	run_test
+	if [ $? -ne 0 ]; then
+		break
+	fi
+done
+
+cleanup
+exit $ret
-- 
2.33.0