extensions: mh: Save/xlate inverted full ranges

Also translate '-m mh' into an exthdr exists match unless '-p mh' is
also present. The latter is converted into 'meta l4proto mh' which might
need fixing itself at a later point.

Fixes: 6d4b93485055a ("extensions: libip6t_mh: Add translation to nft")
Signed-off-by: Phil Sutter <phil@nwl.cc>

3 files changed, 19 insertions, 7 deletions

diff --git a/extensions/libip6t_mh.c b/extensions/libip6t_mh.c
index 1410d324..3f80e28e 100644
--- a/extensions/libip6t_mh.c
+++ b/extensions/libip6t_mh.c
@@ -17,6 +17,7 @@
 #include <stdlib.h>
 #include <xtables.h>
 #include <linux/netfilter_ipv6/ip6t_mh.h>
+#include <linux/netfilter_ipv6/ip6_tables.h>
 
 enum {
 	O_MH_TYPE = 0,
@@ -154,11 +155,16 @@ static void print_type(uint8_t type, int numeric)
 		printf("%s", name);
 }
 
+static bool skip_types_match(uint8_t min, uint8_t max, bool inv)
+{
+	return min == 0 && max == UINT8_MAX && !inv;
+}
+
 static void print_types(uint8_t min, uint8_t max, int invert, int numeric)
 {
 	const char *inv = invert ? "!" : "";
 
-	if (min != 0 || max != 0xFF || invert) {
+	if (!skip_types_match(min, max, invert)) {
 		printf(" ");
 		if (min == max) {
 			printf("%s", inv);
@@ -189,11 +195,12 @@ static void mh_print(const void *ip, const struct xt_entry_match *match,
 static void mh_save(const void *ip, const struct xt_entry_match *match)
 {
 	const struct ip6t_mh *mhinfo = (struct ip6t_mh *)match->data;
+	bool inv_type = mhinfo->invflags & IP6T_MH_INV_TYPE;
 
-	if (mhinfo->types[0] == 0 && mhinfo->types[1] == 0xFF)
+	if (skip_types_match(mhinfo->types[0], mhinfo->types[1], inv_type))
 		return;
 
-	if (mhinfo->invflags & IP6T_MH_INV_TYPE)
+	if (inv_type)
 		printf(" !");
 
 	if (mhinfo->types[0] != mhinfo->types[1])
@@ -206,9 +213,14 @@ static int mh_xlate(struct xt_xlate *xl,
 		    const struct xt_xlate_mt_params *params)
 {
 	const struct ip6t_mh *mhinfo = (struct ip6t_mh *)params->match->data;
+	bool inv_type = mhinfo->invflags & IP6T_MH_INV_TYPE;
+	uint8_t proto = ((const struct ip6t_ip6 *)params->ip)->proto;
 
-	if (mhinfo->types[0] == 0 && mhinfo->types[1] == 0xff)
+	if (skip_types_match(mhinfo->types[0], mhinfo->types[1], inv_type)) {
+		if (proto != IPPROTO_MH)
+			xt_xlate_add(xl, "exthdr mh exists");
 		return 1;
+	}
 
 	if (mhinfo->types[0] != mhinfo->types[1])
 		xt_xlate_add(xl, "mh type %s%u-%u",
diff --git a/extensions/libip6t_mh.t b/extensions/libip6t_mh.t
index 151eabe6..b628e9e3 100644
--- a/extensions/libip6t_mh.t
+++ b/extensions/libip6t_mh.t
@@ -5,7 +5,7 @@
 -p mobility-header -m mh ! --mh-type 4;=;OK
 -p mobility-header -m mh --mh-type 4:123;=;OK
 -p mobility-header -m mh --mh-type :;-p mobility-header -m mh;OK
--p mobility-header -m mh ! --mh-type :;-p mobility-header -m mh;OK
+-p mobility-header -m mh ! --mh-type :;-p mobility-header -m mh ! --mh-type 0:255;OK
 -p mobility-header -m mh --mh-type :3;-p mobility-header -m mh --mh-type 0:3;OK
 -p mobility-header -m mh --mh-type 3:;-p mobility-header -m mh --mh-type 3:255;OK
 -p mobility-header -m mh --mh-type 3:3;-p mobility-header -m mh --mh-type 3;OK
diff --git a/extensions/libip6t_mh.txlate b/extensions/libip6t_mh.txlate
index 825c9569..3364ce57 100644
--- a/extensions/libip6t_mh.txlate
+++ b/extensions/libip6t_mh.txlate
@@ -8,7 +8,7 @@ ip6tables-translate -A INPUT -p mh --mh-type 0:255 -j ACCEPT
 nft 'add rule ip6 filter INPUT meta l4proto mobility-header counter accept'
 
 ip6tables-translate -A INPUT -m mh --mh-type 0:255 -j ACCEPT
-nft 'add rule ip6 filter INPUT counter accept'
+nft 'add rule ip6 filter INPUT exthdr mh exists counter accept'
 
 ip6tables-translate -A INPUT -p mh ! --mh-type 0:255 -j ACCEPT
-nft 'add rule ip6 filter INPUT meta l4proto mobility-header counter accept'
+nft 'add rule ip6 filter INPUT meta l4proto mobility-header mh type != 0-255 counter accept'