Re: [PATCH net-next v2] net/sched: cls_api: complement tcf_tfilter_dump_policy

[Cong Wang]

On Thu, Dec 28, 2023 at 02:43:58PM +0800, Lin Ma wrote:
> In function `tc_dump_tfilter`, the attributes array is parsed via
> tcf_tfilter_dump_policy which only describes TCA_DUMP_FLAGS. However,
> the NLA TCA_CHAIN is also accessed with `nla_get_u32`.
> 
> The access to TCA_CHAIN is introduced in commit 5bc1701881e3 ("net:
> sched: introduce multichain support for filters") and no nla_policy is
> provided for parsing at that point. Later on, tcf_tfilter_dump_policy is
> introduced in commit f8ab1807a9c9 ("net: sched: introduce terse dump
> flag") while still ignoring the fact that TCA_CHAIN needs a check. This
> patch does that by complementing the policy to allow the access
> discussed here can be safe as other cases just choose rtm_tca_policy as
> the parsing policy.
> 

This patch looks good but you could use NLA_POLICY_MAX() to validate
TCA_CHAIN while you are on it.

Thanks.