netfilter: xtables: avoid NFPROTO_UNSPEC where needed

[ Upstream commit 0bfcb7b ]

syzbot managed to call xt_cluster match via ebtables:

 WARNING: CPU: 0 PID: 11 at net/netfilter/xt_cluster.c:72 xt_cluster_mt+0x196/0x780
 [..]
 ebt_do_table+0x174b/0x2a40

Module registers to NFPROTO_UNSPEC, but it assumes ipv4/ipv6 packet
processing.  As this is only useful to restrict locally terminating
TCP/UDP traffic, register this for ipv4 and ipv6 family only.

Pablo points out that this is a general issue, direct users of the
set/getsockopt interface can call into targets/matches that were only
intended for use with ip(6)tables.

Check all UNSPEC matches and targets for similar issues:

- matches and targets are fine except if they assume skb_network_header()
  is valid -- this is only true when called from inet layer: ip(6) stack
  pulls the ip/ipv6 header into linear data area.
- targets that return XT_CONTINUE or other xtables verdicts must be
  restricted too, they are incompatbile with the ebtables traverser, e.g.
  EBT_CONTINUE is a completely different value than XT_CONTINUE.

Most matches/targets are changed to register for NFPROTO_IPV4/IPV6, as
they are provided for use by ip(6)tables.

The MARK target is also used by arptables, so register for NFPROTO_ARP too.

While at it, bail out if connbytes fails to enable the corresponding
conntrack family.

This change passes the selftests in iptables.git.

Reported-by: syzbot+256c348558aa5cf611a9@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netfilter-devel/66fec2e2.050a0220.9ec68.0047.GAE@google.com/
Fixes: 0269ea4 ("netfilter: xtables: add cluster match")
Signed-off-by: Florian Westphal <fw@strlen.de>
Co-developed-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Florian Westphal

net/netfilter/xt_CHECKSUM.c

@@ -63,24 +63,37 @@ static int checksum_tg_check(const struct xt_tgchk_param *par)
 	return 0;
 }
 
-static struct xt_target checksum_tg_reg __read_mostly = {
-	.name		= "CHECKSUM",
-	.family		= NFPROTO_UNSPEC,
-	.target		= checksum_tg,
-	.targetsize	= sizeof(struct xt_CHECKSUM_info),
-	.table		= "mangle",
-	.checkentry	= checksum_tg_check,
-	.me		= THIS_MODULE,
+static struct xt_target checksum_tg_reg[] __read_mostly = {
+	{
+		.name		= "CHECKSUM",
+		.family		= NFPROTO_IPV4,
+		.target		= checksum_tg,
+		.targetsize	= sizeof(struct xt_CHECKSUM_info),
+		.table		= "mangle",
+		.checkentry	= checksum_tg_check,
+		.me		= THIS_MODULE,
+	},
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+	{
+		.name		= "CHECKSUM",
+		.family		= NFPROTO_IPV6,
+		.target		= checksum_tg,
+		.targetsize	= sizeof(struct xt_CHECKSUM_info),
+		.table		= "mangle",
+		.checkentry	= checksum_tg_check,
+		.me		= THIS_MODULE,
+	},
+#endif
 };
 
 static int __init checksum_tg_init(void)
 {
-	return xt_register_target(&checksum_tg_reg);
+	return xt_register_targets(checksum_tg_reg, ARRAY_SIZE(checksum_tg_reg));
 }
 
 static void __exit checksum_tg_exit(void)
 {
-	xt_unregister_target(&checksum_tg_reg);
+	xt_unregister_targets(checksum_tg_reg, ARRAY_SIZE(checksum_tg_reg));
 }
 
 module_init(checksum_tg_init);

net/netfilter/xt_CLASSIFY.c

@@ -38,9 +38,9 @@ static struct xt_target classify_tg_reg[] __read_mostly = {
 	{
 		.name       = "CLASSIFY",
 		.revision   = 0,
-		.family     = NFPROTO_UNSPEC,
+		.family     = NFPROTO_IPV4,
 		.hooks      = (1 << NF_INET_LOCAL_OUT) | (1 << NF_INET_FORWARD) |
-		              (1 << NF_INET_POST_ROUTING),
+			      (1 << NF_INET_POST_ROUTING),
 		.target     = classify_tg,
 		.targetsize = sizeof(struct xt_classify_target_info),
 		.me         = THIS_MODULE,
@@ -54,6 +54,18 @@ static struct xt_target classify_tg_reg[] __read_mostly = {
 		.targetsize = sizeof(struct xt_classify_target_info),
 		.me         = THIS_MODULE,
 	},
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+	{
+		.name       = "CLASSIFY",
+		.revision   = 0,
+		.family     = NFPROTO_IPV6,
+		.hooks      = (1 << NF_INET_LOCAL_OUT) | (1 << NF_INET_FORWARD) |
+			      (1 << NF_INET_POST_ROUTING),
+		.target     = classify_tg,
+		.targetsize = sizeof(struct xt_classify_target_info),
+		.me         = THIS_MODULE,
+	},
+#endif
 };
 
 static int __init classify_tg_init(void)

net/netfilter/xt_CONNSECMARK.c

@@ -114,25 +114,39 @@ static void connsecmark_tg_destroy(const struct xt_tgdtor_param *par)
 	nf_ct_netns_put(par->net, par->family);
 }
 
-static struct xt_target connsecmark_tg_reg __read_mostly = {
-	.name       = "CONNSECMARK",
-	.revision   = 0,
-	.family     = NFPROTO_UNSPEC,
-	.checkentry = connsecmark_tg_check,
-	.destroy    = connsecmark_tg_destroy,
-	.target     = connsecmark_tg,
-	.targetsize = sizeof(struct xt_connsecmark_target_info),
-	.me         = THIS_MODULE,
+static struct xt_target connsecmark_tg_reg[] __read_mostly = {
+	{
+		.name       = "CONNSECMARK",
+		.revision   = 0,
+		.family     = NFPROTO_IPV4,
+		.checkentry = connsecmark_tg_check,
+		.destroy    = connsecmark_tg_destroy,
+		.target     = connsecmark_tg,
+		.targetsize = sizeof(struct xt_connsecmark_target_info),
+		.me         = THIS_MODULE,
+	},
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+	{
+		.name       = "CONNSECMARK",
+		.revision   = 0,
+		.family     = NFPROTO_IPV6,
+		.checkentry = connsecmark_tg_check,
+		.destroy    = connsecmark_tg_destroy,
+		.target     = connsecmark_tg,
+		.targetsize = sizeof(struct xt_connsecmark_target_info),
+		.me         = THIS_MODULE,
+	},
+#endif
 };
 
 static int __init connsecmark_tg_init(void)
 {
-	return xt_register_target(&connsecmark_tg_reg);
+	return xt_register_targets(connsecmark_tg_reg, ARRAY_SIZE(connsecmark_tg_reg));
 }
 
 static void __exit connsecmark_tg_exit(void)
 {
-	xt_unregister_target(&connsecmark_tg_reg);
+	xt_unregister_targets(connsecmark_tg_reg, ARRAY_SIZE(connsecmark_tg_reg));
 }
 
 module_init(connsecmark_tg_init);

net/netfilter/xt_CT.c

@@ -313,10 +313,30 @@ static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
 	xt_ct_tg_destroy(par, par->targinfo);
 }
 
+static unsigned int
+notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
+{
+	/* Previously seen (loopback)? Ignore. */
+	if (skb->_nfct != 0)
+		return XT_CONTINUE;
+
+	nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
+
+	return XT_CONTINUE;
+}
+
 static struct xt_target xt_ct_tg_reg[] __read_mostly = {
+	{
+		.name		= "NOTRACK",
+		.revision	= 0,
+		.family		= NFPROTO_IPV4,
+		.target		= notrack_tg,
+		.table		= "raw",
+		.me		= THIS_MODULE,
+	},
 	{
 		.name		= "CT",
-		.family		= NFPROTO_UNSPEC,
+		.family		= NFPROTO_IPV4,
 		.targetsize	= sizeof(struct xt_ct_target_info),
 		.usersize	= offsetof(struct xt_ct_target_info, ct),
 		.checkentry	= xt_ct_tg_check_v0,
@@ -327,7 +347,7 @@ static struct xt_target xt_ct_tg_reg[] __read_mostly = {
 	},
 	{
 		.name		= "CT",
-		.family		= NFPROTO_UNSPEC,
+		.family		= NFPROTO_IPV4,
 		.revision	= 1,
 		.targetsize	= sizeof(struct xt_ct_target_info_v1),
 		.usersize	= offsetof(struct xt_ct_target_info, ct),
@@ -339,7 +359,7 @@ static struct xt_target xt_ct_tg_reg[] __read_mostly = {
 	},
 	{
 		.name		= "CT",
-		.family		= NFPROTO_UNSPEC,
+		.family		= NFPROTO_IPV4,
 		.revision	= 2,
 		.targetsize	= sizeof(struct xt_ct_target_info_v1),
 		.usersize	= offsetof(struct xt_ct_target_info, ct),
@@ -349,49 +369,61 @@ static struct xt_target xt_ct_tg_reg[] __read_mostly = {
 		.table		= "raw",
 		.me		= THIS_MODULE,
 	},
-};
-
-static unsigned int
-notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
-{
-	/* Previously seen (loopback)? Ignore. */
-	if (skb->_nfct != 0)
-		return XT_CONTINUE;
-
-	nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
-
-	return XT_CONTINUE;
-}
-
-static struct xt_target notrack_tg_reg __read_mostly = {
-	.name		= "NOTRACK",
-	.revision	= 0,
-	.family		= NFPROTO_UNSPEC,
-	.target		= notrack_tg,
-	.table		= "raw",
-	.me		= THIS_MODULE,
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+	{
+		.name		= "NOTRACK",
+		.revision	= 0,
+		.family		= NFPROTO_IPV6,
+		.target		= notrack_tg,
+		.table		= "raw",
+		.me		= THIS_MODULE,
+	},
+	{
+		.name		= "CT",
+		.family		= NFPROTO_IPV6,
+		.targetsize	= sizeof(struct xt_ct_target_info),
+		.usersize	= offsetof(struct xt_ct_target_info, ct),
+		.checkentry	= xt_ct_tg_check_v0,
+		.destroy	= xt_ct_tg_destroy_v0,
+		.target		= xt_ct_target_v0,
+		.table		= "raw",
+		.me		= THIS_MODULE,
+	},
+	{
+		.name		= "CT",
+		.family		= NFPROTO_IPV6,
+		.revision	= 1,
+		.targetsize	= sizeof(struct xt_ct_target_info_v1),
+		.usersize	= offsetof(struct xt_ct_target_info, ct),
+		.checkentry	= xt_ct_tg_check_v1,
+		.destroy	= xt_ct_tg_destroy_v1,
+		.target		= xt_ct_target_v1,
+		.table		= "raw",
+		.me		= THIS_MODULE,
+	},
+	{
+		.name		= "CT",
+		.family		= NFPROTO_IPV6,
+		.revision	= 2,
+		.targetsize	= sizeof(struct xt_ct_target_info_v1),
+		.usersize	= offsetof(struct xt_ct_target_info, ct),
+		.checkentry	= xt_ct_tg_check_v2,
+		.destroy	= xt_ct_tg_destroy_v1,
+		.target		= xt_ct_target_v1,
+		.table		= "raw",
+		.me		= THIS_MODULE,
+	},
+#endif
 };
 
 static int __init xt_ct_tg_init(void)
 {
-	int ret;
-
-	ret = xt_register_target(&notrack_tg_reg);
-	if (ret < 0)
-		return ret;
-
-	ret = xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
-	if (ret < 0) {
-		xt_unregister_target(&notrack_tg_reg);
-		return ret;
-	}
-	return 0;
+	return xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 }
 
 static void __exit xt_ct_tg_exit(void)
 {
 	xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
-	xt_unregister_target(&notrack_tg_reg);
 }
 
 module_init(xt_ct_tg_init);

net/netfilter/xt_IDLETIMER.c

@@ -458,28 +458,49 @@ static void idletimer_tg_destroy_v1(const struct xt_tgdtor_param *par)
 
 static struct xt_target idletimer_tg[] __read_mostly = {
 	{
-	.name		= "IDLETIMER",
-	.family		= NFPROTO_UNSPEC,
-	.target		= idletimer_tg_target,
-	.targetsize     = sizeof(struct idletimer_tg_info),
-	.usersize	= offsetof(struct idletimer_tg_info, timer),
-	.checkentry	= idletimer_tg_checkentry,
-	.destroy        = idletimer_tg_destroy,
-	.me		= THIS_MODULE,
+		.name		= "IDLETIMER",
+		.family		= NFPROTO_IPV4,
+		.target		= idletimer_tg_target,
+		.targetsize     = sizeof(struct idletimer_tg_info),
+		.usersize	= offsetof(struct idletimer_tg_info, timer),
+		.checkentry	= idletimer_tg_checkentry,
+		.destroy        = idletimer_tg_destroy,
+		.me		= THIS_MODULE,
 	},
 	{
-	.name		= "IDLETIMER",
-	.family		= NFPROTO_UNSPEC,
-	.revision	= 1,
-	.target		= idletimer_tg_target_v1,
-	.targetsize     = sizeof(struct idletimer_tg_info_v1),
-	.usersize	= offsetof(struct idletimer_tg_info_v1, timer),
-	.checkentry	= idletimer_tg_checkentry_v1,
-	.destroy        = idletimer_tg_destroy_v1,
-	.me		= THIS_MODULE,
+		.name		= "IDLETIMER",
+		.family		= NFPROTO_IPV4,
+		.revision	= 1,
+		.target		= idletimer_tg_target_v1,
+		.targetsize     = sizeof(struct idletimer_tg_info_v1),
+		.usersize	= offsetof(struct idletimer_tg_info_v1, timer),
+		.checkentry	= idletimer_tg_checkentry_v1,
+		.destroy        = idletimer_tg_destroy_v1,
+		.me		= THIS_MODULE,
 	},
-
-
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+	{
+		.name		= "IDLETIMER",
+		.family		= NFPROTO_IPV6,
+		.target		= idletimer_tg_target,
+		.targetsize     = sizeof(struct idletimer_tg_info),
+		.usersize	= offsetof(struct idletimer_tg_info, timer),
+		.checkentry	= idletimer_tg_checkentry,
+		.destroy        = idletimer_tg_destroy,
+		.me		= THIS_MODULE,
+	},
+	{
+		.name		= "IDLETIMER",
+		.family		= NFPROTO_IPV6,
+		.revision	= 1,
+		.target		= idletimer_tg_target_v1,
+		.targetsize     = sizeof(struct idletimer_tg_info_v1),
+		.usersize	= offsetof(struct idletimer_tg_info_v1, timer),
+		.checkentry	= idletimer_tg_checkentry_v1,
+		.destroy        = idletimer_tg_destroy_v1,
+		.me		= THIS_MODULE,
+	},
+#endif
 };
 
 static struct class *idletimer_tg_class;

net/netfilter/xt_LED.c

@@ -175,26 +175,41 @@ static void led_tg_destroy(const struct xt_tgdtor_param *par)
 	kfree(ledinternal);
 }
 
-static struct xt_target led_tg_reg __read_mostly = {
-	.name		= "LED",
-	.revision	= 0,
-	.family		= NFPROTO_UNSPEC,
-	.target		= led_tg,
-	.targetsize	= sizeof(struct xt_led_info),
-	.usersize	= offsetof(struct xt_led_info, internal_data),
-	.checkentry	= led_tg_check,
-	.destroy	= led_tg_destroy,
-	.me		= THIS_MODULE,
+static struct xt_target led_tg_reg[] __read_mostly = {
+	{
+		.name		= "LED",
+		.revision	= 0,
+		.family		= NFPROTO_IPV4,
+		.target		= led_tg,
+		.targetsize	= sizeof(struct xt_led_info),
+		.usersize	= offsetof(struct xt_led_info, internal_data),
+		.checkentry	= led_tg_check,
+		.destroy	= led_tg_destroy,
+		.me		= THIS_MODULE,
+	},
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+	{
+		.name		= "LED",
+		.revision	= 0,
+		.family		= NFPROTO_IPV6,
+		.target		= led_tg,
+		.targetsize	= sizeof(struct xt_led_info),
+		.usersize	= offsetof(struct xt_led_info, internal_data),
+		.checkentry	= led_tg_check,
+		.destroy	= led_tg_destroy,
+		.me		= THIS_MODULE,
+	},
+#endif
 };
 
 static int __init led_tg_init(void)
 {
-	return xt_register_target(&led_tg_reg);
+	return xt_register_targets(led_tg_reg, ARRAY_SIZE(led_tg_reg));
 }
 
 static void __exit led_tg_exit(void)
 {
-	xt_unregister_target(&led_tg_reg);
+	xt_unregister_targets(led_tg_reg, ARRAY_SIZE(led_tg_reg));
 }
 
 module_init(led_tg_init);