netdev - Re: [PATCH 1/3 v2] ipv6: do not disable temp_address when reaching max

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Wed, 14 Aug 2013 09:39:17 +0800
From:	Ding Tianhong <dingtianhong@...wei.com>
To:	"David S. Miller" <davem@...emloft.net>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	James Morris <jmorris@...ei.org>,
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
	Patrick McHardy <kaber@...sh.net>,
	Netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH 1/3 v2] ipv6: do not disable temp_address when reaching
 max_address

On 2013/8/13 19:53, Hannes Frederic Sowa wrote:
> On Tue, Aug 13, 2013 at 01:05:21PM +0200, Hannes Frederic Sowa wrote:
>> On Tue, Aug 13, 2013 at 03:57:14PM +0800, Ding Tianhong wrote:
>>> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
>>> index da4241c..72911fd 100644
>>> --- a/net/ipv6/addrconf.c
>>> +++ b/net/ipv6/addrconf.c
>>> @@ -1134,10 +1134,27 @@ retry:
>>>  	if (IS_ERR_OR_NULL(ift)) {
>>>  		in6_ifa_put(ifp);
>>>  		in6_dev_put(idev);
>>> -		pr_info("%s: retry temporary address regeneration\n", __func__);
>>> -		tmpaddr = &addr;
>>> -		write_lock(&idev->lock);
>>> -		goto retry;
>>> +
>>> +		/* According RFC4941 3.3.7:
>>> +		 * If DAD indicates the address is already in use,
>>> +		 * the node must generate a new randomized interface
>>> +		 * identifier as described in section 3.2 above, and
>>> +		 * repeat the previous steps as appropriate up to
>>> +		 * TEMP_IDGEN_RETRIES times.
>>> +		 * If after TEMP_IDGEN_RETRIES consecutive attempts no
>>> +		 * non-unique address was generated, the node must log
>>> +		 * a system error and must not attempt to generate
>>> +		 * temporary address for that interface.
>>> +		 * So we have to check the return err and distinguish
>>> +		 * the correct retry path.
>>> +		 */
>>> +		if (PTR_ERR(ift) == -EEXIST) {
>>> +			pr_info("%s: retry temporary address regeneration\n", __func__);
>>> +			tmpaddr = &addr;
>>> +			write_lock(&idev->lock);
>>> +			goto retry;
>>> +		} else
>>> +			goto out;
>>
>> Correct me if I am wrong, but the RFC referes by mentioning "in use" to
>> allocated on the subnet and not in use by this host. I don't see how this
>> fixes the CVE then. dad is triggered by ipv6_add_addr.
> 
> Eric already posted a proposal. It seems it lacked testing. Maybe you could
> start from this?
> 
> http://permalink.gmane.org/gmane.linux.network/253518
> 
> Thanks for looking into this,
> 
>   Hannes
> 

the patch could not solve the problem, the use_tempaddr will still be -1 after the attack.

> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> .
> 


--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html