Subject: Re: [PATCH net-next 2/3] xfrm: clamp down spi range for IPComp when allocating spi

From: Fan Du <[email-masked]>
Date: Mon, 9 Dec 2013 17:13:52 +0800

On 2013年12月09日 16:57, Steffen Klassert wrote:
> On Mon, Dec 09, 2013 at 02:27:43PM +0800, Fan Du wrote:
>> On 2013年12月06日 19:42, Steffen Klassert wrote:
>>>
>>> Also, the spi range is user defined, we should respect the
>>> users configuration if the range is valid.
>>
>> Ok, then, speaking of respect user defined range, how about below informal
>> patch which only check the validity of the range? My original thoughts is CPI
>> is only 16bits wide, kernel itself can keep the CPI's validity. btw, v2 will
>> also fix patch1/3 align issue.
>>
>> diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
>> index 6a9c402..2c6fb99 100644
>> --- a/net/xfrm/xfrm_state.c
>> +++ b/net/xfrm/xfrm_state.c
>> @@ -1507,6 +1507,9 @@ int xfrm_alloc_spi(struct xfrm_state *x, u32 low, u32 high)
>>
>>          err = -ENOENT;
>>
>> +       if ((x->id.proto == IPPROTO_COMP)&&  (high>  0xFFFF))
>> +               goto unlock;
>> +
>
> This check is already done in verify_userspi_info() if xfrm_alloc_spi()
> is called from xfrm_alloc_userspi().
>
> Instead of doing this check here again, we should implement an equivalent
> to verify_userspi_info() for pfkey. Then we are sure to have a valid range
> in any case.
>

How about export an common function in xfrm_state.c to check this corner case?
This could be shared by both netlink and pfkey interface, and verify_userspi_info
simplified also?

int check_ipcomp_spirange(u8 proto, u32 high)
{
	if ((proto == IPPROTO_COMP) && (high > 0xFFFF))
		return -EINVAL;
	else return 0;
}
EXPORT_SYMBOL(check_ipcomp_spirange);

-- 
浮沉随浪只记今朝笑

--fan