[PATCH] net: netfilter: Add RFC-7597 Section 5.1 PSID support xtables API

[Cole Dishington <Cole.Dishington@alliedtelesis.co.nz>]

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)
-- 
2.32.0