netdev - Re: [PATCH net-next 1/2] ipv6: add ipv6_fragment hook in ipv6

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Date:   Fri, 28 Aug 2020 07:33:10 +0800
From:   wenxu <wenxu@...oud.cn>
To:     Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH net-next 1/2] ipv6: add ipv6_fragment hook in ipv6_stub

Yes， I check the ipv6_stub->ipv6_fragment. And in the case

if there is no ipv6_stub->ipv6_fragment it means no ipv6 fragment support

and it should free the skb.

Maybe sometimes  not all the calling remember to check with this? So

it should add a default one with following?

+static int eafnosupport_ipv6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
+                                     int (*output)(struct net *, struct sock *, struct sk_buff *))
+{
+       kfree_skb(skb);
+       return -EAFNOSUPPORT;
+}
+

在 2020/8/28 6:38, Marcelo Ricardo Leitner 写道:
> On Thu, Aug 27, 2020 at 07:51:47AM -0700, David Miller wrote:
>> From: wenxu@...oud.cn
>> Date: Thu, 27 Aug 2020 18:39:51 +0800
>>
>>> From: wenxu <wenxu@...oud.cn>
>>>
>>> Add ipv6_fragment to ipv6_stub to avoid calling netfilter when
>>> access ip6_fragment.
>>>
>>> Signed-off-by: wenxu <wenxu@...oud.cn>
>> Please test these changes with ipv6 disabled.
>>
>> It will crash, you have to update the default stub in
>> net/ipv6/addrconf_core.c as well.
> I didn't test it myself but I'm not seeing how the crash could happen.
> The next patch does check for it being NULL before using it:
>
> -               if (!v6ops)
> +               if (!ipv6_stub->ipv6_fragment)
>                         goto err;
>
> Wenxu?
>
>   Marcelo
>