netfilter: nf_tables: use NLA_POLICY_MASK to test for valid flag options

nf_tables relies on manual test of netlink attributes coming from userspace
even in cases where this could be handled via netlink policy.

Convert a bunch of 'flag' attributes to use NLA_POLICY_MASK checks.

Signed-off-by: Florian Westphal <[e-mail]>

net/netfilter/nft_fib.c

···
 #include <net/netfilter/nf_tables.h>
 #include <net/netfilter/nft_fib.h>
 
-const struct nla_policy nft_fib_policy[NFTA_FIB_MAX + 1] = {
-	[NFTA_FIB_DREG]		= { .type = NLA_U32 },
-	[NFTA_FIB_RESULT]	= { .type = NLA_U32 },
-	[NFTA_FIB_FLAGS]	= { .type = NLA_U32 },
-};
-EXPORT_SYMBOL(nft_fib_policy);
-
 #define NFTA_FIB_F_ALL (NFTA_FIB_F_SADDR | NFTA_FIB_F_DADDR | \
 			NFTA_FIB_F_MARK | NFTA_FIB_F_IIF | NFTA_FIB_F_OIF | \
 			NFTA_FIB_F_PRESENT)
+
+const struct nla_policy nft_fib_policy[NFTA_FIB_MAX + 1] = {
+	[NFTA_FIB_DREG]		= { .type = NLA_U32 },
+	[NFTA_FIB_RESULT]	= { .type = NLA_U32 },
+	[NFTA_FIB_FLAGS]	=
+		NLA_POLICY_MASK(NLA_BE32, NFTA_FIB_F_ALL),
+};
+EXPORT_SYMBOL(nft_fib_policy);
 
 int nft_fib_validate(const struct nft_ctx *ctx, const struct nft_expr *expr,
 		     const struct nft_data **data)
···
 
 	priv->flags = ntohl(nla_get_be32(tb[NFTA_FIB_FLAGS]));
 
-	if (priv->flags == 0 || (priv->flags & ~NFTA_FIB_F_ALL))
+	if (priv->flags == 0)
 		return -EINVAL;
 
 	if ((priv->flags & (NFTA_FIB_F_SADDR | NFTA_FIB_F_DADDR)) ==

net/netfilter/nft_lookup.c

···
 	[NFTA_LOOKUP_SET_ID]	= { .type = NLA_U32 },
 	[NFTA_LOOKUP_SREG]	= { .type = NLA_U32 },
 	[NFTA_LOOKUP_DREG]	= { .type = NLA_U32 },
-	[NFTA_LOOKUP_FLAGS]	= { .type = NLA_U32 },
+	[NFTA_LOOKUP_FLAGS]	=
+		NLA_POLICY_MASK(NLA_BE32, NFT_LOOKUP_F_INV),
 };
 
 static int nft_lookup_init(const struct nft_ctx *ctx,
···
 
 	if (tb[NFTA_LOOKUP_FLAGS]) {
 		flags = ntohl(nla_get_be32(tb[NFTA_LOOKUP_FLAGS]));
-
-		if (flags & ~NFT_LOOKUP_F_INV)
-			return -EINVAL;
 
 		if (flags & NFT_LOOKUP_F_INV)
 			priv->invert = true;

net/netfilter/nft_masq.c

···
 };
 
 static const struct nla_policy nft_masq_policy[NFTA_MASQ_MAX + 1] = {
-	[NFTA_MASQ_FLAGS]		= { .type = NLA_U32 },
+	[NFTA_MASQ_FLAGS]		=
+		NLA_POLICY_MASK(NLA_BE32, NF_NAT_RANGE_MASK),
 	[NFTA_MASQ_REG_PROTO_MIN]	= { .type = NLA_U32 },
 	[NFTA_MASQ_REG_PROTO_MAX]	= { .type = NLA_U32 },
 };
···
 	struct nft_masq *priv = nft_expr_priv(expr);
 	int err;
 
-	if (tb[NFTA_MASQ_FLAGS]) {
+	if (tb[NFTA_MASQ_FLAGS])
 		priv->flags = ntohl(nla_get_be32(tb[NFTA_MASQ_FLAGS]));
-		if (priv->flags & ~NF_NAT_RANGE_MASK)
-			return -EINVAL;
-	}
 
 	if (tb[NFTA_MASQ_REG_PROTO_MIN]) {
 		err = nft_parse_register_load(tb[NFTA_MASQ_REG_PROTO_MIN],

net/netfilter/nft_nat.c

···
 	[NFTA_NAT_REG_ADDR_MAX]	 = { .type = NLA_U32 },
 	[NFTA_NAT_REG_PROTO_MIN] = { .type = NLA_U32 },
 	[NFTA_NAT_REG_PROTO_MAX] = { .type = NLA_U32 },
-	[NFTA_NAT_FLAGS]	 = { .type = NLA_U32 },
+	[NFTA_NAT_FLAGS]	 =
+		NLA_POLICY_MASK(NLA_BE32, NF_NAT_RANGE_MASK),
 };
 
 static int nft_nat_validate(const struct nft_ctx *ctx,
···
 		priv->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
 	}
 
-	if (tb[NFTA_NAT_FLAGS]) {
+	if (tb[NFTA_NAT_FLAGS])
 		priv->flags |= ntohl(nla_get_be32(tb[NFTA_NAT_FLAGS]));
-		if (priv->flags & ~NF_NAT_RANGE_MASK)
-			return -EOPNOTSUPP;
-	}
 
 	return nf_ct_netns_get(ctx->net, family);
 }

net/netfilter/nft_redir.c

···
 static const struct nla_policy nft_redir_policy[NFTA_REDIR_MAX + 1] = {
 	[NFTA_REDIR_REG_PROTO_MIN]	= { .type = NLA_U32 },
 	[NFTA_REDIR_REG_PROTO_MAX]	= { .type = NLA_U32 },
-	[NFTA_REDIR_FLAGS]		= { .type = NLA_U32 },
+	[NFTA_REDIR_FLAGS]		=
+		NLA_POLICY_MASK(NLA_BE32, NF_NAT_RANGE_MASK),
 };
 
 static int nft_redir_validate(const struct nft_ctx *ctx,
···
 		priv->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
 	}
 
-	if (tb[NFTA_REDIR_FLAGS]) {
+	if (tb[NFTA_REDIR_FLAGS])
 		priv->flags = ntohl(nla_get_be32(tb[NFTA_REDIR_FLAGS]));
-		if (priv->flags & ~NF_NAT_RANGE_MASK)
-			return -EINVAL;
-	}
 
 	return nf_ct_netns_get(ctx->net, ctx->family);
 }