linux-kernel - [PATCH 3.16 072/245] netfilter: nf_tables: validate NFT_DATA_VALUE after nft_data

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Message-ID: <lsq.1587683028.807471934@decadent.org.uk>
Date:   Fri, 24 Apr 2020 00:04:59 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Pablo Neira Ayuso" <pablo@...filter.org>
Subject: [PATCH 3.16 072/245] netfilter: nf_tables: validate
 NFT_DATA_VALUE after nft_data_init()

3.16.83-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Pablo Neira Ayuso <pablo@...filter.org>

commit 0d2c96af797ba149e559c5875c0151384ab6dd14 upstream.

Userspace might bogusly sent NFT_DATA_VERDICT in several netlink
attributes that assume NFT_DATA_VALUE. Moreover, make sure that error
path invokes nft_data_release() to decrement the reference count on the
chain object.

Fixes: 96518518cc41 ("netfilter: add nftables")
Fixes: 0f3cd9b36977 ("netfilter: nf_tables: add range expression")
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
[bwh: Backported to 3.16:
 - Drop changes in nft_get_set_elem(), nft_range
 - Call nft_data_uninit() instead of nft_data_release()
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/net/netfilter/nft_bitwise.c
+++ b/net/netfilter/nft_bitwise.c
@@ -86,7 +86,7 @@ static int nft_bitwise_init(const struct
 	err = nft_data_init(NULL, &priv->mask, &d1, tb[NFTA_BITWISE_MASK]);
 	if (err < 0)
 		return err;
-	if (d1.len != priv->len) {
+	if (d1.type != NFT_DATA_VALUE || d1.len != priv->len) {
 		err = -EINVAL;
 		goto err1;
 	}
@@ -94,7 +94,7 @@ static int nft_bitwise_init(const struct
 	err = nft_data_init(NULL, &priv->xor, &d2, tb[NFTA_BITWISE_XOR]);
 	if (err < 0)
 		goto err1;
-	if (d2.len != priv->len) {
+	if (d2.type != NFT_DATA_VALUE || d2.len != priv->len) {
 		err = -EINVAL;
 		goto err2;
 	}
--- a/net/netfilter/nft_cmp.c
+++ b/net/netfilter/nft_cmp.c
@@ -84,6 +84,12 @@ static int nft_cmp_init(const struct nft
 	if (desc.len > U8_MAX)
 		return -ERANGE;
 
+	if (desc.type != NFT_DATA_VALUE) {
+		err = -EINVAL;
+		nft_data_uninit(&priv->data, desc.type);
+		return err;
+	}
+
 	priv->len = desc.len;
 	return 0;
 }