netfilter: nft_inner: validate mandatory meta and payload

Check for mandatory netlink attributes in payload and meta expression
when used embedded from the inner expression, otherwise NULL pointer
dereference is possible from userspace.

Fixes: a150d12 ("netfilter: nft_meta: add inner match support")
Fixes: 3a07327 ("netfilter: nft_inner: support for inner tunnel header matching")
Signed-off-by: Davide Ornaghi <d.ornaghi97@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_meta.c

@@ -839,6 +839,9 @@ static int nft_meta_inner_init(const struct nft_ctx *ctx,
 	struct nft_meta *priv = nft_expr_priv(expr);
 	unsigned int len;
 
+	if (!tb[NFTA_META_KEY] || !tb[NFTA_META_DREG])
+		return -EINVAL;
+
 	priv->key = ntohl(nla_get_be32(tb[NFTA_META_KEY]));
 	switch (priv->key) {
 	case NFT_META_PROTOCOL:

net/netfilter/nft_payload.c

@@ -650,6 +650,10 @@ static int nft_payload_inner_init(const struct nft_ctx *ctx,
 	struct nft_payload *priv = nft_expr_priv(expr);
 	u32 base;
 
+	if (!tb[NFTA_PAYLOAD_BASE] || !tb[NFTA_PAYLOAD_OFFSET] ||
+	    !tb[NFTA_PAYLOAD_LEN] || !tb[NFTA_PAYLOAD_DREG])
+		return -EINVAL;
+
 	base   = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
 	switch (base) {
 	case NFT_PAYLOAD_TUN_HEADER: