[PATCH 09/12] netfilter: nf_tables: missing sanitization in data from userspace

[Pablo Neira Ayuso]

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 <pa...@netfilter.org>
---
 net/netfilter/nft_bitwise.c | 19 ++++++++++++++-----
 net/netfilter/nft_cmp.c     | 12 ++++++++++--
 2 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/net/netfilter/nft_bitwise.c b/net/netfilter/nft_bitwise.c
index 877d9acd91ef..96bd4f325b0f 100644
--- a/net/netfilter/nft_bitwise.c
+++ b/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)
diff --git a/net/netfilter/nft_cmp.c b/net/netfilter/nft_cmp.c
index 2b96effeadc1..8c9d0fb19118 100644
--- a/net/netfilter/nft_cmp.c
+++ b/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 = {
-- 
2.1.4