netdev - Re: [PATCH net-next v11 3/4] net sched actions: dump more than TCA_ACT_MAX

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Date:   Fri, 28 Jul 2017 16:12:34 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Jamal Hadi Salim <jhs@...atatu.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org,
        xiyou.wangcong@...il.com, dsahern@...il.com,
        eric.dumazet@...il.com, mrv@...atatu.com,
        simon.horman@...ronome.com, alex.aring@...il.com
Subject: Re: [PATCH net-next v11 3/4] net sched actions: dump more than
 TCA_ACT_MAX_PRIO actions per batch

Fri, Jul 28, 2017 at 03:41:44PM CEST, jhs@...atatu.com wrote:
>On 17-07-25 08:37 AM, Jiri Pirko wrote:
>> Tue, Jul 25, 2017 at 02:34:58PM CEST, jhs@...atatu.com wrote:
>> > On 17-07-25 07:33 AM, Jiri Pirko wrote:
>> > > Tue, Jul 25, 2017 at 01:22:44PM CEST, jhs@...atatu.com wrote:
>
>[..]
>> > > What if I pass val 0x1 and selector 0x0 from userspace. I don't have the
>> > > bit selected, so you should not process it in kernel, no?
>> > > 
>> > 
>> > Yes, valid point. I am not sure - should we reject?
>> 
>> I think that the validation might check this and reject. Makes sense to
>> me.
>> 
>
>How does this look? I havent tested it but covers all angles

Looks like a big mess to be honest. Mixing up u32* u32 void*. I don't
understand ****. Would be probably good to first apply my review comment
on the function itselt, then to add the checks :)


>I can think of.
>
>static int validate_nla_bitfield32(const struct nlattr *nla,
>                                    void *valid_flags_allowed)
>{
>        const struct nla_bitfield32 *bf = nla_data(nla);
>        u32 *valid_flags_mask = valid_flags_allowed;
>
>        if (!valid_flags_allowed)
>                return -EINVAL;
>        /*disallow invalid selector */
>        if ((bf->selector & valid_flags_allowed) >*valid_flags_allowed)
>                return -EINVAL;
>        /*disallow invalid bit values */
>        if (bf->value & ~*valid_flags_mask)
>                return -EINVAL;
>        /*disallow valid bit values that are not selected*/
>        if (bf->value & ~nbf->selector)
>                return -EINVAL;
>
>        return 0;
>}
>
>cheers,
>jamal