[PATCH net 05/14] netfilter: nft_compat: run xt_check_hooks_{match,target}() from .validate

Pablo Neira Ayuso
2026-05-01T12:22:50Z

Several matches and one target check that the hook is correct from
checkentry(), however, the basechain is only available from
nft_table_validate().

This patch uses xt_check_hooks_{match,target}() from the nft_compat
expression .validate path.

This patch sets the table in the nft_ctx struct in nft_table_validate()
which is required by this patch.

Based on patch from Florian Westphal.

Fixes: 0ca743a55991 ("netfilter: nf_tables: add compatibility layer for x_tables")
Reported-by: Xiang Mei <xmei5@asu.edu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
net/netfilter/nf_tables_api.c | 1 +
net/netfilter/nft_compat.c | 45 +++++++++++++++++++++++++++--------
2 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index d20ce5c36d31..38e33c66c618 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -4205,6 +4205,7 @@ static int nft_table_validate(struct net *net, const struct nft_table *table)
struct nft_chain *chain;
struct nft_ctx ctx = {
.net = net,
+ .table = (struct nft_table *)table,
.family = table->family,
};
int err = 0;
diff --git a/net/netfilter/nft_compat.c b/net/netfilter/nft_compat.c
index decc725a33c2..0caa9304d2d0 100644
--- a/net/netfilter/nft_compat.c
+++ b/net/netfilter/nft_compat.c
@@ -261,10 +261,10 @@ nft_target_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
return ret;
}

- nft_target_set_tgchk_param(&par, ctx, target, info, &e, proto, inv);
-
nft_compat_wait_for_destructors(ctx->net);

+ nft_target_set_tgchk_param(&par, ctx, target, info, &e, proto, inv);
+
ret = xt_check_target(&par, size, proto, inv);
if (ret < 0) {
if (ret == -ENOENT) {
@@ -353,8 +353,6 @@ static int nft_target_dump(struct sk_buff *skb,
static int nft_target_validate(const struct nft_ctx *ctx,
const struct nft_expr *expr)
{
- struct xt_target *target = expr->ops->data;
- unsigned int hook_mask = 0;
int ret;

if (ctx->family != NFPROTO_IPV4 &&
@@ -377,11 +375,21 @@ static int nft_target_validate(const struct nft_ctx *ctx,
const struct nft_base_chain *basechain =
nft_base_chain(ctx->chain);
const struct nf_hook_ops *ops = &basechain->ops;
+ unsigned int hook_mask = 1 << ops->hooknum;
+ struct xt_target *target = expr->ops->data;
+ void *info = nft_expr_priv(expr);
+ struct xt_tgchk_param par;
+ union nft_entry e = {};

- hook_mask = 1 << ops->hooknum;
if (target->hooks && !(hook_mask & target->hooks))
return -EINVAL;

+ nft_target_set_tgchk_param(&par, ctx, target, info, &e, 0, false);
+
+ ret = xt_check_hooks_target(&par);
+ if (ret < 0)
+ return ret;
+
ret = nft_compat_chain_validate_dependency(ctx, target->table);
if (ret < 0)
return ret;
@@ -515,10 +523,10 @@ __nft_match_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
return ret;
}

- nft_match_set_mtchk_param(&par, ctx, match, info, &e, proto, inv);
-
nft_compat_wait_for_destructors(ctx->net);

+ nft_match_set_mtchk_param(&par, ctx, match, info, &e, proto, inv);
+
return xt_check_match(&par, size, proto, inv);
}

@@ -614,8 +622,6 @@ static int nft_match_large_dump(struct sk_buff *skb,
static int nft_match_validate(const struct nft_ctx *ctx,
const struct nft_expr *expr)
{
- struct xt_match *match = expr->ops->data;
- unsigned int hook_mask = 0;
int ret;

if (ctx->family != NFPROTO_IPV4 &&
@@ -638,11 +644,30 @@ static int nft_match_validate(const struct nft_ctx *ctx,
const struct nft_base_chain *basechain =
nft_base_chain(ctx->chain);
const struct nf_hook_ops *ops = &basechain->ops;
+ unsigned int hook_mask = 1 << ops->hooknum;
+ struct xt_match *match = expr->ops->data;
+ size_t size = XT_ALIGN(match->matchsize);
+ struct xt_mtchk_param par;
+ union nft_entry e = {};
+ void *info;

- hook_mask = 1 << ops->hooknum;
if (match->hooks && !(hook_mask & match->hooks))
return -EINVAL;

+ if (NFT_EXPR_SIZE(size) > NFT_MATCH_LARGE_THRESH) {
+ struct nft_xt_match_priv *priv = nft_expr_priv(expr);
+
+ info = priv->info;
+ } else {
+ info = nft_expr_priv(expr);
+ }
+
+ nft_match_set_mtchk_param(&par, ctx, match, info, &e, 0, false);
+
+ ret = xt_check_hooks_match(&par);
+ if (ret < 0)
+ return ret;
+
ret = nft_compat_chain_validate_dependency(ctx, match->table);
if (ret < 0)
return ret;
--
2.47.3