Re: [PATCH v4] netfilter: nf_tables: Ensure init attributes are within the bounds

[Pablo Neira Ayuso <pablo@netfilter.org>]

Hi Laura,

On Thu, Aug 18, 2016 at 06:06:26PM +0200, Laura Garcia Liebana wrote:
> Check for overflow of u8 fields from u32 netlink attributes and maximum
> values.

After a closer look, this lack of validation seems more widespread
than I initially expected.

Look, other enums like:

enum nft_set_policies {
        NFT_SET_POL_PERFORMANCE,
        NFT_SET_POL_MEMORY,
};

that has no _MAX definition are suspect, actually looking at
net/netfilter/nf_tables_api.c more specifically at
nft_select_set_ops() you'll notice that the switch there doesn't seem
to reject anything over NFT_SET_POL_MEMORY.

So I would review net/netfilter/nf_tables_api.c too.

BTW, I think it is a good idea to add something like:

	err = nft_parse_u8(ntohl(nla_get_be32(tb[NFTA_BITWISE_LEN]),
                           &priv->len);
        if (err < 0)
                return err;

that we can consistently use all over the code, instead of open
coding:

        len = ...
        if (len > U8_MAX)
                return -ERANGE;

> Refer to 4da449ae1df

Please, use this format instead to refer to patches:

4da449a ("netfilter: nft_exthdr: Add size check on u8 nft_exthdr attributes")

Thanks!