[PATCH 3.16 071/245] netfilter: nf_tables: missing sanitization in data from userspace

Ben Hutchings
2020-04-23T23:20:42Z

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

commit 71df14b0ce094be46d105b5a3ededd83b8e779a0 upstream.

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 <pablo@netfilter.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/netfilter/nft_bitwise.c | 19 ++++++++++++++-----
net/netfilter/nft_cmp.c | 12 ++++++++++--
2 files changed, 24 insertions(+), 7 deletions(-)

--- a/net/netfilter/nft_bitwise.c
+++ b/net/netfilter/nft_bitwise.c
@@ -86,16 +86,25 @@ 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)
- return -EINVAL;
+ if (d1.len != priv->len) {
+ err = -EINVAL;
+ goto err1;
+ }

err = nft_data_init(NULL, &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)
--- a/net/netfilter/nft_cmp.c
+++ b/net/netfilter/nft_cmp.c
@@ -201,10 +201,18 @@ nft_cmp_select_ops(const struct nft_ctx
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);
}

static struct nft_expr_type nft_cmp_type __read_mostly = {