xtables: extend matches and targets with .usersize

In matches and targets that define a kernel-only tail to their
xt_match and xt_target data structs, add a field .usersize that
specifies up to where data is to be shared with userspace.

Performed a search for comment "Used internally by the kernel" to find
relevant matches and targets. Manually inspected the structs to derive
a valid offsetof.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/bridge/netfilter/ebt_limit.c

@@ -105,6 +105,7 @@ static struct xt_match ebt_limit_mt_reg __read_mostly = {
 	.match		= ebt_limit_mt,
 	.checkentry	= ebt_limit_mt_check,
 	.matchsize	= sizeof(struct ebt_limit_info),
+	.usersize	= offsetof(struct ebt_limit_info, prev),
 #ifdef CONFIG_COMPAT
 	.compatsize	= sizeof(struct ebt_compat_limit_info),
 #endif

net/ipv4/netfilter/ipt_CLUSTERIP.c

@@ -468,6 +468,7 @@ static struct xt_target clusterip_tg_reg __read_mostly = {
 	.checkentry	= clusterip_tg_check,
 	.destroy	= clusterip_tg_destroy,
 	.targetsize	= sizeof(struct ipt_clusterip_tgt_info),
+	.usersize	= offsetof(struct ipt_clusterip_tgt_info, config),
 #ifdef CONFIG_COMPAT
 	.compatsize	= sizeof(struct compat_ipt_clusterip_tgt_info),
 #endif /* CONFIG_COMPAT */

net/ipv6/netfilter/ip6t_NPT.c

@@ -112,6 +112,7 @@ static struct xt_target ip6t_npt_target_reg[] __read_mostly = {
 		.table		= "mangle",
 		.target		= ip6t_snpt_tg,
 		.targetsize	= sizeof(struct ip6t_npt_tginfo),
+		.usersize	= offsetof(struct ip6t_npt_tginfo, adjustment),
 		.checkentry	= ip6t_npt_checkentry,
 		.family		= NFPROTO_IPV6,
 		.hooks		= (1 << NF_INET_LOCAL_IN) |
@@ -123,6 +124,7 @@ static struct xt_target ip6t_npt_target_reg[] __read_mostly = {
 		.table		= "mangle",
 		.target		= ip6t_dnpt_tg,
 		.targetsize	= sizeof(struct ip6t_npt_tginfo),
+		.usersize	= offsetof(struct ip6t_npt_tginfo, adjustment),
 		.checkentry	= ip6t_npt_checkentry,
 		.family		= NFPROTO_IPV6,
 		.hooks		= (1 << NF_INET_PRE_ROUTING) |

net/netfilter/xt_CT.c

@@ -373,6 +373,7 @@ static struct xt_target xt_ct_tg_reg[] __read_mostly = {
 		.name		= "CT",
 		.family		= NFPROTO_UNSPEC,
 		.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,
@@ -384,6 +385,7 @@ static struct xt_target xt_ct_tg_reg[] __read_mostly = {
 		.family		= NFPROTO_UNSPEC,
 		.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,
@@ -395,6 +397,7 @@ static struct xt_target xt_ct_tg_reg[] __read_mostly = {
 		.family		= NFPROTO_UNSPEC,
 		.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,

net/netfilter/xt_RATEEST.c

@@ -162,6 +162,7 @@ static struct xt_target xt_rateest_tg_reg __read_mostly = {
 	.checkentry = xt_rateest_tg_checkentry,
 	.destroy    = xt_rateest_tg_destroy,
 	.targetsize = sizeof(struct xt_rateest_target_info),
+	.usersize   = offsetof(struct xt_rateest_target_info, est),
 	.me         = THIS_MODULE,
 };
 

net/netfilter/xt_TEE.c

@@ -133,6 +133,7 @@ static struct xt_target tee_tg_reg[] __read_mostly = {
 		.family     = NFPROTO_IPV4,
 		.target     = tee_tg4,
 		.targetsize = sizeof(struct xt_tee_tginfo),
+		.usersize   = offsetof(struct xt_tee_tginfo, priv),
 		.checkentry = tee_tg_check,
 		.destroy    = tee_tg_destroy,
 		.me         = THIS_MODULE,
@@ -144,6 +145,7 @@ static struct xt_target tee_tg_reg[] __read_mostly = {
 		.family     = NFPROTO_IPV6,
 		.target     = tee_tg6,
 		.targetsize = sizeof(struct xt_tee_tginfo),
+		.usersize   = offsetof(struct xt_tee_tginfo, priv),
 		.checkentry = tee_tg_check,
 		.destroy    = tee_tg_destroy,
 		.me         = THIS_MODULE,

net/netfilter/xt_bpf.c

@@ -110,6 +110,7 @@ static struct xt_match bpf_mt_reg[] __read_mostly = {
 		.match		= bpf_mt,
 		.destroy	= bpf_mt_destroy,
 		.matchsize	= sizeof(struct xt_bpf_info),
+		.usersize	= offsetof(struct xt_bpf_info, filter),
 		.me		= THIS_MODULE,
 	},
 	{
@@ -120,6 +121,7 @@ static struct xt_match bpf_mt_reg[] __read_mostly = {
 		.match		= bpf_mt_v1,
 		.destroy	= bpf_mt_destroy_v1,
 		.matchsize	= sizeof(struct xt_bpf_info_v1),
+		.usersize	= offsetof(struct xt_bpf_info_v1, filter),
 		.me		= THIS_MODULE,
 	},
 };

net/netfilter/xt_cgroup.c

@@ -122,6 +122,7 @@ static struct xt_match cgroup_mt_reg[] __read_mostly = {
 		.checkentry	= cgroup_mt_check_v1,
 		.match		= cgroup_mt_v1,
 		.matchsize	= sizeof(struct xt_cgroup_info_v1),
+		.usersize	= offsetof(struct xt_cgroup_info_v1, priv),
 		.destroy	= cgroup_mt_destroy_v1,
 		.me		= THIS_MODULE,
 		.hooks		= (1 << NF_INET_LOCAL_OUT) |

net/netfilter/xt_connlimit.c

@@ -431,6 +431,7 @@ static struct xt_match connlimit_mt_reg __read_mostly = {
 	.checkentry = connlimit_mt_check,
 	.match      = connlimit_mt,
 	.matchsize  = sizeof(struct xt_connlimit_info),
+	.usersize   = offsetof(struct xt_connlimit_info, data),
 	.destroy    = connlimit_mt_destroy,
 	.me         = THIS_MODULE,
 };

net/netfilter/xt_hashlimit.c

@@ -838,6 +838,7 @@ static struct xt_match hashlimit_mt_reg[] __read_mostly = {
 		.family         = NFPROTO_IPV4,
 		.match          = hashlimit_mt_v1,
 		.matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
+		.usersize	= offsetof(struct xt_hashlimit_mtinfo1, hinfo),
 		.checkentry     = hashlimit_mt_check_v1,
 		.destroy        = hashlimit_mt_destroy_v1,
 		.me             = THIS_MODULE,
@@ -848,6 +849,7 @@ static struct xt_match hashlimit_mt_reg[] __read_mostly = {
 		.family         = NFPROTO_IPV4,
 		.match          = hashlimit_mt,
 		.matchsize      = sizeof(struct xt_hashlimit_mtinfo2),
+		.usersize	= offsetof(struct xt_hashlimit_mtinfo2, hinfo),
 		.checkentry     = hashlimit_mt_check,
 		.destroy        = hashlimit_mt_destroy,
 		.me             = THIS_MODULE,
@@ -859,6 +861,7 @@ static struct xt_match hashlimit_mt_reg[] __read_mostly = {
 		.family         = NFPROTO_IPV6,
 		.match          = hashlimit_mt_v1,
 		.matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
+		.usersize	= offsetof(struct xt_hashlimit_mtinfo1, hinfo),
 		.checkentry     = hashlimit_mt_check_v1,
 		.destroy        = hashlimit_mt_destroy_v1,
 		.me             = THIS_MODULE,
@@ -869,6 +872,7 @@ static struct xt_match hashlimit_mt_reg[] __read_mostly = {
 		.family         = NFPROTO_IPV6,
 		.match          = hashlimit_mt,
 		.matchsize      = sizeof(struct xt_hashlimit_mtinfo2),
+		.usersize	= offsetof(struct xt_hashlimit_mtinfo2, hinfo),
 		.checkentry     = hashlimit_mt_check,
 		.destroy        = hashlimit_mt_destroy,
 		.me             = THIS_MODULE,

net/netfilter/xt_limit.c

@@ -192,6 +192,8 @@ static struct xt_match limit_mt_reg __read_mostly = {
 	.compatsize       = sizeof(struct compat_xt_rateinfo),
 	.compat_from_user = limit_mt_compat_from_user,
 	.compat_to_user   = limit_mt_compat_to_user,
+#else
+	.usersize         = offsetof(struct xt_rateinfo, prev),
 #endif
 	.me               = THIS_MODULE,
 };

net/netfilter/xt_quota.c

@@ -73,6 +73,7 @@ static struct xt_match quota_mt_reg __read_mostly = {
 	.checkentry = quota_mt_check,
 	.destroy    = quota_mt_destroy,
 	.matchsize  = sizeof(struct xt_quota_info),
+	.usersize   = offsetof(struct xt_quota_info, master),
 	.me         = THIS_MODULE,
 };
 

net/netfilter/xt_rateest.c

@@ -133,6 +133,7 @@ static struct xt_match xt_rateest_mt_reg __read_mostly = {
 	.checkentry = xt_rateest_mt_checkentry,
 	.destroy    = xt_rateest_mt_destroy,
 	.matchsize  = sizeof(struct xt_rateest_match_info),
+	.usersize   = offsetof(struct xt_rateest_match_info, est1),
 	.me         = THIS_MODULE,
 };
 

net/netfilter/xt_string.c

@@ -77,6 +77,7 @@ static struct xt_match xt_string_mt_reg __read_mostly = {
 	.match      = string_mt,
 	.destroy    = string_mt_destroy,
 	.matchsize  = sizeof(struct xt_string_info),
+	.usersize   = offsetof(struct xt_string_info, config),
 	.me         = THIS_MODULE,
 };