linux-kernel - Re: [PATCH] af_key: fix netns ops ordering on module load/unload

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Date:	Mon, 1 Feb 2010 14:50:02 +0100
From:	Luca Tettamanti <kronos.it@...il.com>
To:	Alexey Dobriyan <adobriyan@...il.com>
Cc:	Eric Dumazet <eric.dumazet@...il.com>,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	David Miller <davem@...emloft.net>
Subject: Re: [PATCH] af_key: fix netns ops ordering on module load/unload

On Sat, Jan 30, 2010 at 1:53 PM, Alexey Dobriyan <adobriyan@...il.com> wrote:
> On Fri, Jan 29, 2010 at 05:33:26PM +0100, Eric Dumazet wrote:
>> @@ -3807,21 +3807,24 @@ static int __init ipsec_pfkey_init(void)
>>       if (err != 0)
>>               goto out;
>>
>> -     err = sock_register(&pfkey_family_ops);
>> -     if (err != 0)
>> -             goto out_unregister_key_proto;
>>       err = xfrm_register_km(&pfkeyv2_mgr);
>>       if (err != 0)
>> -             goto out_sock_unregister;
>> +             goto out_unregister_key_proto;
>> +
>>       err = register_pernet_subsys(&pfkey_net_ops);
>>       if (err != 0)
>>               goto out_xfrm_unregister_km;
>> +
>> +     err = sock_register(&pfkey_family_ops);
>> +     if (err != 0)
>> +             goto out_unregister_pernet;
>>  out:
>>       return err;
>> +
>> +out_unregister_pernet:
>> +     unregister_pernet_subsys(&pfkey_net_ops);
>>  out_xfrm_unregister_km:
>>       xfrm_unregister_km(&pfkeyv2_mgr);
>> -out_sock_unregister:
>> -     sock_unregister(PF_KEY);
>>  out_unregister_key_proto:
>>       proto_unregister(&key_proto);
>>       goto out;
>
> ACK analysis, except this is not enough.
>
> Here is patch which survived netns start/stop/modprobe/rmmod cycles.
>
>        Alexey, who still doesn't get why bug reproduces so easily for bug reporter.
>
> Luca, please confirm.

Seems to work fine.

> [PATCH] af_key: fix netns ops ordering on module load/unload
>
> 1. After sock_register() returns, it's possible to create sockets,
>   even if module still not initialized fully (blame generic module code
>   for that!)
> 2. Consequently, pfkey_create() can be called with pfkey_net_id still not
>   initialized which will BUG_ON in net_generic():
>        kernel BUG at include/net/netns/generic.h:43!
> 3. During netns shutdown, netns ops should be unregistered after
>   key manager unregistered because key manager calls can be triggered
>   from xfrm_user module:
>
>        general protection fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
>        pfkey_broadcast+0x111/0x210 [af_key]
>        pfkey_send_notify+0x16a/0x300 [af_key]
>        km_state_notify+0x41/0x70
>        xfrm_flush_sa+0x75/0x90 [xfrm_user]
> 4. Unregister netns ops after socket ops just in case and for symmetry.
>
> Reported by Luca Tettamanti.
>
> Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>

Tested-by: Luca Tettamanti <kronos.it@...il.com>

thanks,
Luca
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