Re: [PATCH nf] netfilter: nf_tables: report error if stateful obj's name is truncated

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

On Thu, Jan 19, 2017 at 10:00:20PM +0800, Liping Zhang wrote:
> From: Liping Zhang <zlpnobody@gmail.com>
> 
> Currently, if the user add a stateful object with the name size exceed
> NFT_OBJ_MAXNAMELEN - 1 (i.e. 31), we truncate it down to 31 silently.
> This is not friendly, furthermore, this will cause duplicated stateful
> objects when the first 31 characters of the name is same. So limit the
> stateful object's name size to NFT_OBJ_MAXNAMELEN - 1.
> 
> After apply this patch, error message will be printed out like this:
>   # name_32=$(printf "%0.sQ" {1..32})
>   # nft add counter filter $name_32
>   <cmdline>:1:1-52: Error: Could not process rule: Numerical result out
>   of range
>   add counter filter QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ
>   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Good catch.

At quick glance, I can see other spots lacking this validation:

static const struct nla_policy nft_chain_policy[NFTA_CHAIN_MAX + 1] =
{
        [NFTA_CHAIN_TABLE]      = { .type = NLA_STRING },

Probably review and fix them in one go?