[PATCH net 06/11] netfilter: xtables: restrict several matches to inet family

Pablo Neira Ayuso
2026-04-16T13:15:10Z

This is a partial revert of:

commit ab4f21e6fb1c ("netfilter: xtables: use NFPROTO_UNSPEC in more extensions")

to allow ipv4 and ipv6 only.

- xt_mac
- xt_owner
- xt_physdev

These extensions are not used by ebtables in userspace.

Moreover, xt_realm is only for ipv4, since dst->tclassid is ipv4
specific.

Fixes: ab4f21e6fb1c ("netfilter: xtables: use NFPROTO_UNSPEC in more extensions")
Reported-by: "Kito Xu (veritas501)" <hxzene@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
net/netfilter/xt_mac.c | 34 +++++++++++++++++++++++-----------
net/netfilter/xt_owner.c | 37 +++++++++++++++++++++++++------------
net/netfilter/xt_physdev.c | 29 +++++++++++++++++++----------
net/netfilter/xt_realm.c | 2 +-
4 files changed, 68 insertions(+), 34 deletions(-)

diff --git a/net/netfilter/xt_mac.c b/net/netfilter/xt_mac.c
index 81649da57ba5..bd2354760895 100644
--- a/net/netfilter/xt_mac.c
+++ b/net/netfilter/xt_mac.c
@@ -38,25 +38,37 @@ static bool mac_mt(const struct sk_buff *skb, struct xt_action_param *par)
return ret;
}

-static struct xt_match mac_mt_reg __read_mostly = {
- .name = "mac",
- .revision = 0,
- .family = NFPROTO_UNSPEC,
- .match = mac_mt,
- .matchsize = sizeof(struct xt_mac_info),
- .hooks = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_IN) |
- (1 << NF_INET_FORWARD),
- .me = THIS_MODULE,
+static struct xt_match mac_mt_reg[] __read_mostly = {
+ {
+ .name = "mac",
+ .family = NFPROTO_IPV4,
+ .match = mac_mt,
+ .matchsize = sizeof(struct xt_mac_info),
+ .hooks = (1 << NF_INET_PRE_ROUTING) |
+ (1 << NF_INET_LOCAL_IN) |
+ (1 << NF_INET_FORWARD),
+ .me = THIS_MODULE,
+ },
+ {
+ .name = "mac",
+ .family = NFPROTO_IPV6,
+ .match = mac_mt,
+ .matchsize = sizeof(struct xt_mac_info),
+ .hooks = (1 << NF_INET_PRE_ROUTING) |
+ (1 << NF_INET_LOCAL_IN) |
+ (1 << NF_INET_FORWARD),
+ .me = THIS_MODULE,
+ },
};

static int __init mac_mt_init(void)
{
- return xt_register_match(&mac_mt_reg);
+ return xt_register_matches(mac_mt_reg, ARRAY_SIZE(mac_mt_reg));
}

static void __exit mac_mt_exit(void)
{
- xt_unregister_match(&mac_mt_reg);
+ xt_unregister_matches(mac_mt_reg, ARRAY_SIZE(mac_mt_reg));
}

module_init(mac_mt_init);
diff --git a/net/netfilter/xt_owner.c b/net/netfilter/xt_owner.c
index 50332888c8d2..7be2fe22b067 100644
--- a/net/netfilter/xt_owner.c
+++ b/net/netfilter/xt_owner.c
@@ -127,26 +127,39 @@ owner_mt(const struct sk_buff *skb, struct xt_action_param *par)
return true;
}

-static struct xt_match owner_mt_reg __read_mostly = {
- .name = "owner",
- .revision = 1,
- .family = NFPROTO_UNSPEC,
- .checkentry = owner_check,
- .match = owner_mt,
- .matchsize = sizeof(struct xt_owner_match_info),
- .hooks = (1 << NF_INET_LOCAL_OUT) |
- (1 << NF_INET_POST_ROUTING),
- .me = THIS_MODULE,
+static struct xt_match owner_mt_reg[] __read_mostly = {
+ {
+ .name = "owner",
+ .revision = 1,
+ .family = NFPROTO_IPV4,
+ .checkentry = owner_check,
+ .match = owner_mt,
+ .matchsize = sizeof(struct xt_owner_match_info),
+ .hooks = (1 << NF_INET_LOCAL_OUT) |
+ (1 << NF_INET_POST_ROUTING),
+ .me = THIS_MODULE,
+ },
+ {
+ .name = "owner",
+ .revision = 1,
+ .family = NFPROTO_IPV6,
+ .checkentry = owner_check,
+ .match = owner_mt,
+ .matchsize = sizeof(struct xt_owner_match_info),
+ .hooks = (1 << NF_INET_LOCAL_OUT) |
+ (1 << NF_INET_POST_ROUTING),
+ .me = THIS_MODULE,
+ }
};

static int __init owner_mt_init(void)
{
- return xt_register_match(&owner_mt_reg);
+ return xt_register_matches(owner_mt_reg, ARRAY_SIZE(owner_mt_reg));
}

static void __exit owner_mt_exit(void)
{
- xt_unregister_match(&owner_mt_reg);
+ xt_unregister_matches(owner_mt_reg, ARRAY_SIZE(owner_mt_reg));
}

module_init(owner_mt_init);
diff --git a/net/netfilter/xt_physdev.c b/net/netfilter/xt_physdev.c
index 343e65f377d4..130842c35c6f 100644
--- a/net/netfilter/xt_physdev.c
+++ b/net/netfilter/xt_physdev.c
@@ -115,24 +115,33 @@ static int physdev_mt_check(const struct xt_mtchk_param *par)
return 0;
}

-static struct xt_match physdev_mt_reg __read_mostly = {
- .name = "physdev",
- .revision = 0,
- .family = NFPROTO_UNSPEC,
- .checkentry = physdev_mt_check,
- .match = physdev_mt,
- .matchsize = sizeof(struct xt_physdev_info),
- .me = THIS_MODULE,
+static struct xt_match physdev_mt_reg[] __read_mostly = {
+ {
+ .name = "physdev",
+ .family = NFPROTO_IPV4,
+ .checkentry = physdev_mt_check,
+ .match = physdev_mt,
+ .matchsize = sizeof(struct xt_physdev_info),
+ .me = THIS_MODULE,
+ },
+ {
+ .name = "physdev",
+ .family = NFPROTO_IPV6,
+ .checkentry = physdev_mt_check,
+ .match = physdev_mt,
+ .matchsize = sizeof(struct xt_physdev_info),
+ .me = THIS_MODULE,
+ },
};

static int __init physdev_mt_init(void)
{
- return xt_register_match(&physdev_mt_reg);
+ return xt_register_matches(physdev_mt_reg, ARRAY_SIZE(physdev_mt_reg));
}

static void __exit physdev_mt_exit(void)
{
- xt_unregister_match(&physdev_mt_reg);
+ xt_unregister_matches(physdev_mt_reg, ARRAY_SIZE(physdev_mt_reg));
}

module_init(physdev_mt_init);
diff --git a/net/netfilter/xt_realm.c b/net/netfilter/xt_realm.c
index 6df485f4403d..61b2f1e58d15 100644
--- a/net/netfilter/xt_realm.c
+++ b/net/netfilter/xt_realm.c
@@ -33,7 +33,7 @@ static struct xt_match realm_mt_reg __read_mostly = {
.matchsize = sizeof(struct xt_realm_info),
.hooks = (1 << NF_INET_POST_ROUTING) | (1 << NF_INET_FORWARD) |
(1 << NF_INET_LOCAL_OUT) | (1 << NF_INET_LOCAL_IN),
- .family = NFPROTO_UNSPEC,
+ .family = NFPROTO_IPV4,
.me = THIS_MODULE
};

--
2.47.3