netfilter: nf_tables: missing sanitization in data from userspace

Do not assume userspace always sends us NFT_DATA_VALUE for bitwise and
cmp expressions. Although NFT_DATA_VERDICT does not make any sense, it
is still possible to handcraft a netlink message using this incorrect
data type.

Signed-off-by: Pablo Neira Ayuso <[email protected]>

Author: ummakynes

net/netfilter/nft_bitwise.c

@@ -83,17 +83,26 @@ static int nft_bitwise_init(const struct nft_ctx *ctx,
 			    tb[NFTA_BITWISE_MASK]);
 	if (err < 0)
 		return err;
-	if (d1.len != priv->len)
-		return -EINVAL;
+	if (d1.len != priv->len) {
+		err = -EINVAL;
+		goto err1;
+	}
 
 	err = nft_data_init(NULL, &priv->xor, sizeof(priv->xor), &d2,
 			    tb[NFTA_BITWISE_XOR]);
 	if (err < 0)
-		return err;
-	if (d2.len != priv->len)
-		return -EINVAL;
+		goto err1;
+	if (d2.len != priv->len) {
+		err = -EINVAL;
+		goto err2;
+	}
 
 	return 0;
+err2:
+	nft_data_uninit(&priv->xor, d2.type);
+err1:
+	nft_data_uninit(&priv->mask, d1.type);
+	return err;
 }
 
 static int nft_bitwise_dump(struct sk_buff *skb, const struct nft_expr *expr)

net/netfilter/nft_cmp.c

@@ -201,10 +201,18 @@ nft_cmp_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
 	if (err < 0)
 		return ERR_PTR(err);
 
+	if (desc.type != NFT_DATA_VALUE) {
+		err = -EINVAL;
+		goto err1;
+	}
+
 	if (desc.len <= sizeof(u32) && op == NFT_CMP_EQ)
 		return &nft_cmp_fast_ops;
-	else
-		return &nft_cmp_ops;
+
+	return &nft_cmp_ops;
+err1:
+	nft_data_uninit(&data, desc.type);
+	return ERR_PTR(-EINVAL);
 }
 
 struct nft_expr_type nft_cmp_type __read_mostly = {